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High power regulators for inductive loads. Single-phase thyristor regulator with active load. For the diagram "Load connection indicator"

A selection of circuits and a description of the operation of a power regulator using triacs and more. Triac power regulator circuits are well suited for extending the life of incandescent lamps and for adjusting their brightness. Or for powering non-standard equipment, for example, 110 volts.

The figure shows a circuit of a triac power regulator, which can be changed by changing the total number of network half-cycles passed by the triac over a certain time interval. The elements of the DD1.1.DD1.3 microcircuit are made with an oscillation period of about 15-25 network half-cycles.

The duty cycle of the pulses is regulated by resistor R3. Transistor VT1 together with diodes VD5-VD8 is designed to bind the moment the triac is turned on during the transition of the mains voltage through zero. Basically, this transistor is open, respectively, a “1” is sent to the input DD1.4 and transistor VT2 with triac VS1 are closed. At the moment of crossing zero, transistor VT1 closes and opens almost immediately. In this case, if the output DD1.3 was 1, then the state of the elements DD1.1.DD1.6 will not change, and if the output DD1.3 was “zero”, then the elements DD1.4.DD1.6 will generate a short pulse, which will be amplified by transistor VT2 and open the triac.

As long as there is a logical zero at the output of the generator, the process will proceed cyclically after each transition of the mains voltage through the zero point.

The basis of the circuit is a foreign triac mac97a8, which allows you to switch high-power connected loads, and to regulate it I used an old Soviet variable resistor, and used a regular LED as an indication.

The triac power regulator uses the principle of phase control. The operation of the power regulator circuit is based on changing the moment the triac is turned on relative to the transition of the mains voltage through zero. At the initial moment of the positive half-cycle, the triac is in the closed state. As the mains voltage increases, capacitor C1 is charged through a divider.

The increasing voltage on the capacitor is shifted in phase from the mains voltage by an amount depending on the total resistance of both resistors and the capacitance of the capacitor. The capacitor is charged until the voltage across it reaches the “breakdown” level of the dinistor, approximately 32 V.

At the moment the dinistor opens, the triac will also open, and a current will flow through the load connected to the output, depending on the total resistance of the open triac and the load. The triac will be open until the end of the half-cycle. With resistor VR1 we set the opening voltage of the dinistor and triac, thereby regulating the power. At the time of the negative half-cycle, the circuit operation algorithm is similar.

Option of the circuit with minor modifications for 3.5 kW

The controller circuit is simple, the load power at the output of the device is 3.5 kW. With this homemade amateur radio you can adjust lighting, heating elements and much more. The only significant drawback of this circuit is that you cannot connect an inductive load to it under any circumstances, because the triac will burn out!


Radio components used in the design: Triac T1 - BTB16-600BW or similar (KU 208 or VTA, VT). Dinistor T - type DB3 or DB4. Capacitor 0.1 µF ceramic.

Resistance R2 510 Ohm limits the maximum volts on the capacitor to 0.1 μF; if you put the regulator slider in the 0 Ohm position, the circuit resistance will be about 510 Ohms. The capacitance is charged through resistors R2 510 Ohm and variable resistance R1 420 kOhm, after U on the capacitor reaches the opening level of dinistor DB3, the latter will generate a pulse that unlocks the triac, after which, with further passage of the sinusoid, the triac is locked. The opening and closing frequency of T1 depends on the level of U on the 0.1 μF capacitor, which depends on the resistance of the variable resistor. That is, by interrupting the current (with a high frequency) the circuit thereby regulates the output power.

With each positive half-wave of the input alternating voltage, capacitance C1 is charged through a chain of resistors R3, R4, when the voltage on capacitor C1 becomes equal to the opening voltage of dinistor VD7, its breakdown will occur and the capacitance will be discharged through the diode bridge VD1-VD4, as well as resistance R1 and control electrode VS1. To open the triac, an electrical chain of diodes VD5, VD6, capacitor C2 and resistance R5 is used.

It is necessary to select the value of resistor R2 so that at both half-waves of the mains voltage, the regulator triac operates reliably, and it is also necessary to select the values ​​of resistances R3 and R4 so that when rotating the variable resistance knob R4, the voltage on the load smoothly changes from minimum to maximum values. Instead of the TC 2-80 triac, you can use TC2-50 or TC2-25, although there will be a slight loss in the permissible power in the load.

KU208G, TS106-10-4, TS 112-10-4 and their analogs were used as a triac. At the moment when the triac is closed, capacitor C1 is charged through the connected load and resistors R1 and R2. The charging speed is changed by resistor R2, resistor R1 is designed to limit the maximum value of the charge current

When the threshold voltage value is reached on the capacitor plates, the switch opens, capacitor C1 is quickly discharged to the control electrode and switches the triac from the closed state to the open state; in the open state, the triac bypasses the circuit R1, R2, C1. At the moment the mains voltage passes through zero, the triac closes, then capacitor C1 is charged again, but with a negative voltage.

Capacitor C1 from 0.1...1.0 µF. Resistor R2 1.0...0.1 MOhm. The triac is switched on by a positive current pulse to the control electrode with a positive voltage at the conventional anode terminal and by a negative current pulse to the control electrode with a negative voltage at the conventional cathode. Thus, the key element for the regulator must be bidirectional. You can use a bidirectional dinistor as a key.

Diodes D5-D6 are used to protect the thyristor from possible breakdown by reverse voltage. The transistor operates in avalanche breakdown mode. Its breakdown voltage is about 18-25 volts. If you don’t find P416B, then you can try to find a replacement for it.

The pulse transformer is wound on a ferrite ring with a diameter of 15 mm, grade N2000. The thyristor can be replaced with KU201

The circuit of this power regulator is similar to the circuits described above, only the interference suppression circuit C2, R3 is introduced, and the switch SW makes it possible to break the charging circuit of the control capacitor, which leads to instant locking of the triac and disconnecting the load.

C1, C2 - 0.1 MKF, R1-4k7, R2-2 mOhm, R3-220 Ohm, VR1-500 kOhm, DB3 - dinistor, BTA26-600B - triac, 1N4148/16 V - diode, any LED.

The regulator is used to regulate load power in circuits up to 2000 W, incandescent lamps, heating devices, soldering iron, asynchronous motors, car charger, and if you replace the triac with a more powerful one, it can be used in the current regulation circuit in welding transformers.

The principle of operation of this power regulator circuit is that the load receives a half-cycle of the mains voltage after a selected number of skipped half-cycles.


The diode bridge rectifies alternating voltage. Resistor R1 and zener diode VD2, together with the filter capacitor, form a 10 V power source to power the K561IE8 microcircuit and the KT315 transistor. The rectified positive half-cycles of the voltage passing through capacitor C1 are stabilized by the zener diode VD3 at a level of 10 V. Thus, pulses with a frequency of 100 Hz follow to the counting input C of the K561IE8 counter. If switch SA1 is connected to output 2, then a logical one level will be constantly present at the base of the transistor. Because the microcircuit reset pulse is very short and the counter manages to restart from the same pulse.

Pin 3 will be set to a logical one level. The thyristor will be open. All power will be released at the load. In all subsequent positions of SA1 at pin 3 of the counter, one pulse will pass through 2-9 pulses.

The K561IE8 chip is a decimal counter with a positional decoder at the output, so the logical one level will be periodic at all outputs. However, if the switch is installed on output 5 (pin 1), then counting will only occur up to 5. When the pulse passes through output 5, the microcircuit will be reset to zero. Counting will begin from zero, and a logical one level will appear at pin 3 for the duration of one half-cycle. During this time, the transistor and thyristor open, one half-cycle passes to the load. To make it clearer, I present vector diagrams of the circuit operation.

If you need to reduce the load power, you can add another counter chip by connecting pin 12 of the previous chip to pin 14 of the next one. By installing another switch, you can adjust the power up to 99 missed pulses. Those. you can get about a hundredth of the total power.

The KR1182PM1 microcircuit has two thyristors and a control unit for them. The maximum input voltage of the KR1182PM1 microcircuit is about 270 Volts, and the maximum load can reach 150 Watts without the use of an external triac and up to 2000 W with the use, and also taking into account the fact that the triac will be installed on the radiator.


To reduce the level of external noise, capacitor C1 and inductor L1 are used, and capacitance C4 is required for smooth switching on of the load. The adjustment is carried out using resistance R3.

A selection of fairly simple regulator circuits for a soldering iron will make life easier for a radio amateur.

Combination consists in combining the ease of use of a digital regulator and the flexibility of adjusting a simple one.


The considered power regulator circuit works on the principle of changing the number of periods of the input alternating voltage going to the load. This means that the device cannot be used to adjust the brightness of incandescent lamps due to visible blinking. The circuit makes it possible to regulate power within eight preset values.

There are a huge number of classic thyristor and triac regulator circuits, but this regulator is made on a modern element base and, in addition, was phase-based, i.e. does not transmit the entire half-wave of the mains voltage, but only a certain part of it, thereby limiting the power, since the triac opens only at the required phase angle.

Krasimir Rilchev's thyristor charging unit is designed for charging batteries of trucks and tractors. It provides a continuously adjustable (resistor RP1) charging current of up to 30 A. The principle of regulation is phase-pulse based on thyristors, providing maximum efficiency, minimum power dissipation and not requiring powerful rectifier diodes. The network transformer is made on a magnetic core with a cross-section of 40 cm2, the primary winding contains 280 turns of PEL-1.6, the secondary winding contains 2x28 turns of PEL-3.0. Thyristors are installed on 120x120 mm radiators. ...

For the diagram "SIMPLE SOLDERING IRON TIP TEMPERATURE REGULATOR"

Consumer electronics SIMPLE TEMPERATURE TIPS SOLDERING IRON GRISCHENKO 394000, Voronezh, Malo-Smolskaya st., 6 - 3. This circuit is not my own design. I saw her for the first time in Radio magazine. I think it will interest many radio amateurs due to its simplicity. The device allows you to adjust the power of the soldering iron from half to maximum. With the elements indicated in the diagram, the power loads should not exceed 50 W, but within an hour the circuit can carry a load of 100 W without any special consequences. The regulator circuit is shown in the figure. If the thyristor VD2 is replaced by KU201, and the diode VD1 by KD203V, the connected power can be significantly increased. The output power is minimal in the leftmost (according to the diagram) position of the R2 engine. In my version, it is mounted in a table lamp stand using the hinged mounting method. This saves one power outlet, which, as is clear, is always in short supply. This one has been working for me for 14 years without any complaints. Literature 1. Radio, 1975, N6, P.53....

For the circuit "POWER REGULATOR WITH FEEDBACK"

For the circuit "VOLTAGE CONVERTER PN-32"

Power supply VOLTAGE CONVERTER PN-32(S) RINTELSai Oleg, (RA3XBJ). The converter is designed to power equipment with a rated voltage of 12 V (CB radio stations, radios, televisions, etc.) from the on-board network of cars with a voltage of 24 V. Maximum current loads converter up to 3A short-term and 2-2.5 A long-term (determined by the area of ​​the output transistor radiator). Efficiency 75-90% depending on load current. The converter circuit does not contain any scarce parts. The inductor is wound on a ferrite ring with a diameter of 32 mm and has 50 turns of PETV-0.63 wire. Dimensions of the converter are 65x90x40 mm. Questions about the design can be asked to the author [email protected]...

Power supply "SOFT" LOAD IN THE ELECTRICAL NETWORK When connecting and disconnecting loads Interference often occurs in the electrical network, which disrupts the normal operation of sensitive electronic devices and electrical systems. The device, the diagram of which is shown in Fig. 1, implements "soft" connection and disconnection of the load. =SOFT LOAD IN THE ELECTRICAL NETWORKPuc.1When the contacts of switch SA1 are closed during the charging of capacitor C1 (through resistor R1), transistor VT1 gradually opens and the collector current gradually increases to a value determined by the ratio of the resistances of resistors R1 and R2. Accordingly, the current in the load gradually increases. When turned off, the capacitor discharges through resistor R2 and the base-emitter junction of the transistor. The current gradually decreases to zero. With the values ​​of the elements and a power of 200 W indicated in the diagram, the duration of the switching process is 0.1 s, and the switching off process is 0.5 s. T160 current regulator circuit The voltage losses in this device are relatively small, they are determined by the sum of the forward drop on two diodes and the collector-emitter section of the operating transistor, which is approximately: Uce(B)=0.7+R1*In/h21e Depending on the current loads and the current transfer coefficient of the base of the transistor, resistor R) should be selected so that the voltage drop across the transistor and the power dissipation on it are maintained in the on state at an acceptable level. =SOFT LOAD IN THE ELECTRICAL NETWORKPuc.2In the version of the device shown in Fig. 2, protection against overloads and short circuits is provided. When the current exceeds the set value, the drop...

For the diagram "Load connection indicator"

Looking for a light switch or socket in the dark is not a pleasant experience. Household light switches equipped with indicators that highlight their location have appeared on sale. By slightly improving the circuit, such an indicator can be turned into a load connection indicator. Connection indicator loads(IPN) is a device built inside the socket and indicating the presence of contact between the inserted power plug from any household appliance and the socket. The indicator is especially convenient if the connected devices do not have their own network indicator. The IPN is also useful for radio-electronic products in which the power indicators are located in the secondary power circuit, since it allows you to check their input circuits. The IPN consists of: - a current sensor loads on diodes VD2...VD6; - L-shaped filter R1-C1; - switch on field-effect transistor VT1; - indication unit on elements VD9, VD10, R2, HL1. If there is no load connected to the XS1 socket, then no current flows through the diodes VD1...VD6, the storage capacitor C1 is discharged and the field-effect transistor VT1 is closed. Power regulator on TS122 25 The drain current VT1 is zero, the HL1 indicator does not light up. When connected loads to socket XS1 current loads flows through a back-to-back diode VD1 and a chain of diodes VD2...VD6. Negative half-waves of the mains voltage pass through VD1. and positive ones - through VD2... .VD6. The voltage drop across the diodes VD2...VD6 is fed through resistor R1 to storage capacitor C1 and charges it to a value exceeding the cutoff voltage of field-effect transistor VT1. Transistor VT1 opens, and current flows through its source-drain channel, resistor R2, LED HL1 and diode VD9. The HL1 LED glows dazzlingly, indicating that the load is connected. Resistor R2 is current-limiting, diode VD9 prohibits the flow of current through the load during reverse half-cycles of the mains voltage. Diode VD10 protects HL1 from reverse voltage....

For the "Simple power regulator" circuit

The inductive load in the power regulator circuit places strict demands on the triac management circuits; the management system must be synchronized directly from the supply network; the signal must have a duration equal to the triac conduction interval. The figure shows a diagram of a regulator that meets these requirements, which uses a combination of a dinistor and a triac. The time constant (R4 + R5)C3 determines the delay angle of the unlocking of the dinistor VS1 and therefore the triac VS2. By moving the slider of the variable resistor R5, the power consumed by the load is regulated. Capacitor C2 and resistor R2 are used to synchronize and ensure the duration of the management signal. Capacitor S3 is recharged from C2 after switching since at the end of each half-cycle it receives a voltage of reverse polarity. To protect against interference generated by the regulator, two Filters R1C1 are introduced - in the power circuit and R7C4 - in the load circuit. To set up the device, you need to set resistor R5 to the position of maximum resistance and resistor R3 to set the minimum power on the load Capacitors C1 and C4 type K40P-2B for 400 V, capacitors C2 and SZ type K73-17 for 250 V Diode bridge VD1 can be replaced with diodes KD105B Switch SA1 designed for a current of at least 5 A. V.F. Yakovlev, Shostka, Sumy region. ...

For the "Telephone line holding device" circuit

TelephonyTelephone line holding device The proposed device performs the function of holding a telephone line ("HOLD"), which allows you to hang up the handset during a conversation and go to a parallel telephone set. The device does not overload the telephone line (TL) or create interference in it. At the time of activation, the caller hears a musical background. The diagram of the telephone line holding device is shown in the figure. The rectifier bridge on diodes VD1-VD4 ensures the required polarity of the device’s power supply, regardless of the polarity of its connection to the TL. Switch SF1 is connected to the lever of the telephone set (TA) and closes when the handset is lifted (i.e., it blocks the SB1 button when the handset is on-hook). If during the conversation you need to switch to a parallel telephone, you need to briefly press the SB1 button. In this case, relay K1 is activated (contacts K1.1 are closed, and contacts K1.2 are opened), an equivalent is connected to the TL loads(circuit R1R2K1) and the SLT from which the conversation was conducted is switched off. T160 current regulator circuit Now you can put the handset on the lever and go to the parallel SLT. The voltage drop across the equivalent is 17 V. When the handset is lifted on the parallel SLT, the voltage in the TL drops to 10 V, relay K1 is turned off and the equivalent is disconnected from the TL. Transistor VT1 must have a transmission coefficient of at least 100, while the amplitude of the alternating audio frequency voltage output in the TL reaches 40 mV. The UMS8 microcircuit is used as a musical synthesizer (DD1), in which two melodies and an alarm signal are “hardwired”. Therefore, pin 6 ("melody selection") is connected to pin 5. In this case, the first melody is played once, and then the second one indefinitely. As SF1 m...

For the "STABLE CURRENT GENERATOR" circuit

For the amateur radio designer STABLE CURRENT GENERATOR Devices are commonly called stable current generators. the output current of which is practically independent of the load resistance. It can find application, for example, in ohmmeters with a linear scale. In Fig. Figure 1 shows a schematic diagram of a stable current generator using two silicon transistors. The magnitude of the collector current of transistor V2 is determined by the ratio Ik = 0.66/R2.Puc.1 For example, with R2 equal to 2.2 k0m. the collector current of transistor V2 will be equal to 0.3 mA and remains almost constant when the resistance of the resistor Rx changes from 0 to 30 k0m. If necessary, the value of the direct current can be increased to 3 mA; for this, the resistance of resistor R2 must be reduced to 180 Ohms. A further increase in the current while maintaining high stability of its value both when the load changes and when the temperature increases can only be achieved by using a three-transistor generator shown in Fig. 2. In this case, transistors V2 and V3 should be of average power, and the voltage of the second power source should be 2...3 times greater than the supply voltage of transistors V1, V2. The resistance of resistor R3 is calculated using the above formula, but is additionally adjusted taking into account the spread in the characteristics of the transistors. Puc.2 "Elektrotehnicar" (SFRY), 1976, N 7-8 From the editor. Transistors BC 108 can be replaced with KT315G. VS107 - KT312B, BD137 - KT602B or KT605B, 2N3055 - KT803A....

For the circuit "TRANSISTOR UMZCH ON THE WAY TO PERFECTION"

AUDIO equipmentTRANSISTOR UMZCH ON THE WAY TO IMPROVEMENT PETROV, Mogilev. Usually, when considering the operation of UMZCH, it is assumed that its load is purely active. However, a loudspeaker, and even with anti-aliasing filters, represents a complex complex load. When operating on a complex load, the resulting phase shift between the voltage and current at the output of the amplifier leads to the fact that, with sinusoidal input signals, the load straight line turns into an ellipse. Operating point positions (load curve) for reactive loads the output characteristics of the triode and transistor when amplifying the harmonic signal are shown in Fig. 1 and 2, respectively. As can be seen from Fig. 1, the output characteristics of the triode are almost ideal for a complex load, such as an AC. A favorable spectrum of harmonics (not higher than the fifth) and high linearity largely determine the “softness” of the sound of tube amplifiers. Amateur radio converter circuits At the same time, a single-ended transistor amplifier is completely unsuitable for working with a loudspeaker, because the line enters, on the one hand, into the region limiting the permissible power dissipation on the collector (shaded area, above the hyperbola), on the other, into nonlinear regions at small Uke. The transverse size of the load curve ellipse depends on inductive component of the load, and the longitudinal one - from the active one. When amplifying pulse signals, for example the "meander" type, the line loads is a parallelogram, which makes the situation even worse. The amplitude of the voltage jump at the moment of switching (due to the self-inductive emf) depends on the ratio of the time constant of the signal To to the time constant loads T=L/R...

In electrical engineering, one often encounters problems of regulating alternating voltage, current or power. For example, to regulate the rotation speed of the shaft of a commutator motor, it is necessary to regulate the voltage at its terminals; to control the temperature inside the drying chamber, it is necessary to regulate the power released in the heating elements; to achieve a smooth, shockless start of an asynchronous motor, it is necessary to limit its starting current. A common solution is a device called a thyristor regulator.


Design and principle of operation of a single-phase thyristor voltage regulator


Thyristor regulators are single-phase and three-phase, respectively, for single-phase and three-phase networks and loads. In this article we will look at the simplest single-phase thyristor regulator - in other articles. So, Figure 1 below shows a single-phase thyristor voltage regulator:

Fig. 1 Simple single-phase thyristor regulator with active load

The thyristor regulator itself is outlined in blue lines and includes thyristors VS1-VS2 and a pulse-phase control system (hereinafter referred to as SIFC). Thyristors VS1-VS2 are semiconductor devices that have the property of being closed for the flow of current in the normal state and being open for the flow of current of the same polarity when a control voltage is applied to its control electrode. Therefore, to operate in alternating current networks, two thyristors are required, connected in different directions - one for the flow of the positive half-wave of current, the second for the negative half-wave. This connection of thyristors is called back-to-back.

Single-phase thyristor regulator with active load

This is how a thyristor regulator works. At the initial moment of time, voltage L-N is applied (phase and zero in our example), while control voltage pulses are not supplied to the thyristors, the thyristors are closed, and there is no current in the load Rн. After receiving a command to start, the SIFU begins to generate control pulses according to a specific algorithm (see Fig. 2).



Fig.2 Diagram of voltage and current in an active load

First, the control system synchronizes with the network, that is, it determines the point in time at which the network voltage L-N is zero. This point is called the moment of transition through zero (in foreign literature - Zero Cross). Next, a certain time T1 is counted from the moment of zero crossing and a control pulse is applied to the thyristor VS1. In this case, the thyristor VS1 opens and current flows through the load along the path L-VS1-Rн-N. When the next zero crossing is reached, the thyristor automatically turns off, since it cannot conduct current in the opposite direction. Next, the negative half-cycle of the mains voltage begins. SIFU again counts time T1 relative to the new moment when the voltage crosses zero and generates a second control pulse with thyristor VS2, which opens, and current flows through the load along the path N-Rн-VS2-L. This method of voltage regulation is called phase-pulse.

Time T1 is called the delay time for unlocking the thyristors, time T2 is the conduction time of the thyristors. By changing the unlocking delay time T1, you can adjust the output voltage from zero (pulses are not supplied, the thyristors are closed) to full network voltage, if pulses are supplied immediately at the moment of crossing zero. The unlocking delay time T1 varies within 0..10 ms (10 ms is the duration of one half-cycle of the standard 50 Hz network voltage). They also sometimes talk about times T1 and T2, but they operate not with time, but with electrical degrees. One half-cycle is 180 electrical degrees.

What is the output voltage of a thyristor regulator? As can be seen from Figure 2, it resembles the “cuts” of a sinusoid. Moreover, the longer the T1 time, the less this “cut” resembles a sinusoid. An important practical conclusion follows from this - with phase-pulse regulation, the output voltage is non-sinusoidal. This limits the scope of application - the thyristor regulator cannot be used for loads that do not allow power supply with non-sinusoidal voltage and current. Also in Figure 2 the diagram of the current in the load is shown in red. Since the load is purely active, the current shape follows the voltage shape in accordance with Ohm’s law I=U/R.

The active load case is the most common. One of the most common applications of a thyristor regulator is voltage regulation in heating elements. By adjusting the voltage, the current and the power released in the load change. Therefore, sometimes such a regulator is also called thyristor power regulator. This is true, but still a more correct name is a thyristor voltage regulator, since it is the voltage that is regulated in the first place, and current and power are already derivative quantities.

Voltage and current regulation in active-inductive loads


We looked at the simplest case of an active load. Let's ask ourselves the question: what will change if the load, in addition to the active one, also has an inductive component? For example, active resistance is connected through a step-down transformer (Fig. 3). By the way, this is a very common case.


Fig.3 Thyristor regulator operates on RL load

Let's look closely at Figure 2 from the case of a purely active load. It shows that immediately after the thyristor is turned on, the current in the load almost instantly increases from zero to its limit value, determined by the current value of the voltage and load resistance. It is known from the electrical engineering course that inductance prevents such an abrupt increase in current, so the voltage and current diagram will have a slightly different character:


Fig.4 Voltage and current diagram for RL load

After the thyristor is turned on, the current in the load increases gradually, due to which the current curve is smoothed out. The higher the inductance, the smoother the current curve. What does this give practically?

— The presence of sufficient inductance makes it possible to bring the current shape closer to a sinusoidal one, that is, the inductance acts as a sine filter. In this case, this presence of inductance is due to the properties of the transformer, but often inductance is introduced deliberately in the form of a choke.

— The presence of inductance reduces the amount of interference distributed by the thyristor regulator through the wires and into the radio air. A sharp, almost instantaneous (within a few microseconds) increase in current causes interference that can interfere with the normal operation of other equipment. And if the supply network is “weak”, then something completely curious happens - the thyristor regulator can “jam” itself with its own interference.

— Thyristors have an important parameter - the value of the critical rate of current rise di/dt. For example, for the SKKT162 thyristor module this value is 200 A/µs. Exceeding this value is dangerous, as it can lead to failure of the thyristor. So, the presence of inductance allows the thyristor to remain in the safe operation area, guaranteed not to exceed the limit value di/dt. If this condition is not met, then an interesting phenomenon can be observed - failure of the thyristors, despite the fact that the thyristor current does not exceed their nominal value. For example, the same SKKT162 may fail at a current of 100 A, although it can operate normally up to 200 A. The reason will be the excess of the current rise rate di/dt.

By the way, it must be noted that there is always inductance in the network, even if the load is purely active. Its presence is due, firstly, to the inductance of the windings of the supply transformer substation, secondly, to the intrinsic inductance of the wires and cables and, thirdly, to the inductance of the loop formed by the supply and load wires and cables. And most often, this inductance is enough to ensure that di/dt does not exceed the critical value, so manufacturers usually do not install thyristor regulators, offering them as an option to those who are concerned about the “cleanliness” of the network and the electromagnetic compatibility of devices connected to it.

Let’s also pay attention to the voltage diagram in Figure 4. It also shows that after crossing zero, a small surge of voltage of reverse polarity appears at the load. The reason for its occurrence is the delay in the decline of current in the load by inductance, due to which the thyristor continues to be open even with a negative half-wave voltage. The thyristor is turned off when the current drops to zero with some delay relative to the moment of crossing zero.

Inductive load case


What happens if the inductive component is much larger than the active component? Then we can talk about the case of a purely inductive load. For example, this case can be obtained by disconnecting the load from the output of the transformer from the previous example:


Figure 5 Thyristor regulator with inductive load

A transformer operating in no-load mode is an almost ideal inductive load. In this case, due to the large inductance, the turning off moment of the thyristors shifts closer to the middle of the half-cycle, and the shape of the current curve is smoothed out as much as possible to an almost sinusoidal shape:



Figure 6 Current and voltage diagrams for the case of inductive load

In this case, the load voltage is almost equal to the full network voltage, although the unlocking delay time is only half a half-cycle (90 electric degrees). That is, with a large inductance, we can talk about a shift in the control characteristic. With an active load, the maximum output voltage will be at an unlocking delay angle of 0 electrical degrees, that is, at the moment of crossing zero. With an inductive load, the maximum voltage can be obtained at an unlocking delay angle of 90 electrical degrees, that is, when the thyristor is unlocked at the moment of maximum mains voltage. Accordingly, in the case of an active-inductive load, the maximum output voltage corresponds to the unlocking delay angle in the intermediate range of 0..90 electrical degrees.

SEVERAL SCHEMATIC DIAGRAMS OF POWER REGULATORS

POWER REGULATOR ON TRIAC

Features of the proposed device are the use of a D-trigger to build a generator synchronized with the mains voltage, and a method of controlling a triac using a single pulse, the duration of which is adjusted automatically. Unlike other methods of pulsed control of a triac, this method is not critical to the presence of an inductive component in the load. The generator pulses follow with a period of approximately 1.3 s.
The DD 1 microcircuit is powered by a current flowing through a protective diode located inside the microcircuit between its pins 3 and 14. It flows when the voltage at this pin, connected to the network through resistor R 4 and diode VD 5, exceeds the stabilization voltage of the zener diode VD 4 .

K. GAVRILOV, Radio, 2011, No. 2, p. 41

TWO-CHANNEL POWER CONTROL FOR HEATING DEVICES

The regulator contains two independent channels and allows you to maintain the required temperature for various loads: the temperature of a soldering iron tip, an electric iron, an electric heater, an electric stove, etc. The depth of regulation is 5...95% of the power of the supply network. The regulator circuit is powered by a rectified voltage of 9...11 V with transformer isolation from a 220 V network with low current consumption.


V.G. Nikitenko, O.V. Nikitenko, Radioamator, 2011, No. 4, p. 35

TRIAC POWER REGULATOR

A feature of this triac regulator is that the number of half-cycles of the mains voltage supplied to the load is even at any position of the control. As a result, a constant component of the consumed current is not formed and, therefore, there is no magnetization of the magnetic circuits of transformers and electric motors connected to the regulator. Power is regulated by changing the number of periods of alternating voltage applied to the load over a certain time interval. The regulator is designed to regulate the power of devices with significant inertia (heaters, etc.).
It is not suitable for adjusting the brightness of lighting, since the lamps will blink strongly.

V. KALASHNIK, N. CHEREMISINOVA, V. CHERNIKOV, Radiomir, 2011, No. 5, p. 17 - 18

INTERFERENCE-FREE VOLTAGE REGULATOR

Most voltage (power) regulators are made using thyristors according to a phase-pulse control circuit. It is known that such devices create a noticeable level of radio interference. The proposed regulator is free from this drawback. A feature of the proposed regulator is the control of the amplitude of the alternating voltage, in which the shape of the output signal is not distorted, unlike phase-pulse control.
The regulating element is a powerful transistor VT1 in the diagonal of the diode bridge VD1-VD4, connected in series with the load. The main disadvantage of the device is its low efficiency. When the transistor is closed, no current passes through the rectifier and the load. If control voltage is applied to the base of the transistor, it opens and current begins to flow through its collector-emitter section, diode bridge and load. The voltage at the regulator output (at the load) increases. When the transistor is open and in saturation mode, almost all the mains (input) voltage is applied to the load. The control signal is generated by a low-power power supply assembled on transformer T1, rectifier VD5 and smoothing capacitor C1.
The variable resistor R1 regulates the base current of the transistor, and therefore the amplitude of the output voltage. When the variable resistor slider is moved to the upper position in the diagram, the output voltage decreases, and to the lower position, it increases. Resistor R2 limits the maximum value of the control current. Diode VD6 protects the control unit in the event of breakdown of the collector junction of the transistor. The voltage regulator is mounted on a board made of foiled fiberglass laminate with a thickness of 2.5 mm. Transistor VT1 should be installed on a heat sink with an area of ​​at least 200 cm2. If necessary, diodes VD1-VD4 are replaced with more powerful ones, for example D245A, and are also placed on the heat sink.

If the device is assembled without errors, it starts working immediately and requires virtually no setup. You just need to select resistor R2.
With the KT840B regulating transistor, the load power should not exceed 60 W. It can be replaced with devices: KT812B, KT824A, KT824B, KT828A, KT828B with a permissible power dissipation of 50 W; KT856A -75 W; KT834A, KT834B - 100 W; KT847A-125 W. The load power can be increased if regulating transistors of the same type are connected in parallel: the collectors and emitters are connected to each other, and the bases are connected to the variable resistor motor through separate diodes and resistors.
The device uses a small-sized transformer with a voltage on the secondary winding of 5...8 V. The KTs405E rectifier unit can be replaced with any other one or assembled from individual diodes with a permissible forward current of no less than the required base current of the regulating transistor. The same requirements apply to the VD6 diode. Capacitor C1 - oxide, for example, K50-6, K50-16, etc., with a rated voltage of at least 15 V. Variable resistor R1 - any with a rated dissipation power of 2 W. When installing and setting up the device, precautions should be taken: the regulator elements are under mains voltage. Note: To reduce distortion of the sine wave output voltage, try eliminating capacitor C1. A. Chekarov

Voltage regulator based on MOSFET transistors (IRF540, IRF840)

Oleg Belousov, Electrician, 201 2, No. 12, p. 64 - 66

Since the physical principle of operation of a field-effect transistor with an insulated gate differs from the operation of a thyristor and triac, it can be turned on and off repeatedly during the period of mains voltage. The switching frequency of powerful transistors in this circuit is chosen to be 1 kHz. The advantage of this circuit is its simplicity and the ability to change the duty cycle of the pulses, while slightly changing the pulse repetition rate.

In the author's design, the following pulse durations were obtained: 0.08 ms, with a repetition period of 1 ms, and 0.8 ms, with a repetition period of 0.9 ms, depending on the position of the resistor R2 slider.
You can turn off the voltage on the load by closing switch S 1, while a voltage close to the voltage at pin 7 of the microcircuit is set at the gates of the MOSFET transistors. With the toggle switch open, the voltage at the load in the author's copy of the device could be changed with resistor R 2 within the range of 18...214 V (measured by a TES 2712 type device).
The schematic diagram of such a regulator is shown in the figure below. The regulator uses a domestic K561LN2 microcircuit on two elements of which a generator with adjustable sensitivity is assembled, and four elements are used as current amplifiers.

To avoid interference via the 220 network, it is recommended to connect a choke wound on a ferrite ring with a diameter of 20...30 mm in series with the load until it is filled with 1 mm of wire.

Load current generator based on bipolar transistors (KT817, 2SC3987)

Butov A.L., Radioconstructor, 201 2, No. 7, p. 11 - 12

To check the functionality and configure power supplies, it is convenient to use a load simulator in the form of an adjustable current generator. Using such a device, you can not only quickly set up a power supply and voltage stabilizer, but also, for example, use it as a stable current generator for charging and discharging batteries, electrolysis devices, for electrochemical etching of printed circuit boards, as a current stabilizer for electric lamps, for “soft” start of commutator electric motors.
The device is a two-terminal device, does not require an additional power source and can be connected to the power supply circuit of various devices and actuators.
Current adjustment range from 0...0, 16 to 3 A, maximum power consumption (dissipation) 40 W, supply voltage range 3...30 V DC. The current consumption is regulated by variable resistor R6. The further to the left the slider of resistor R6 is in the diagram, the more current the device consumes. With open contacts of switch SA 1, resistor R6 can set the consumption current from 0.16 to 0.8 A. With closed contacts of this switch, the current is regulated in the range of 0.7... 3 A.



Current generator circuit board drawing

Car battery simulator (KT827)

V. MELNICHUK, Radiomir, 201 2, No. 1 2, p. 7 - 8

When converting computer switching power supplies (UPS) and chargers for car batteries, the finished products must be loaded with something during the setup process. Therefore, I decided to make an analogue of a powerful zener diode with an adjustable stabilization voltage, the circuits of which are shown in Fig. 1 . Resistor R 6 can be used to regulate the stabilization voltage from 6 to 16 V. A total of two such devices were made. In the first version, KT 803 is used as transistors VT 1 and VT 2.
The internal resistance of such a zener diode turned out to be too high. So, at a current of 2 A, the stabilization voltage was 12 V, and at 8 A - 16 V. In the second version, composite transistors KT827 were used. Here, at a current of 2 A, the stabilization voltage was 12 V, and at 10 A - 12.4 V.

However, when regulating more powerful consumers, for example electric boilers, triac power regulators become unsuitable - they will create too much interference on the network. To solve this problem, it is better to use regulators with a longer period of ON-OFF modes, which clearly eliminates the occurrence of interference. One of the diagram options is shown.

Triac power regulators operate using phase control. They can be used to change the power of various electrical devices operating using alternating voltage.

The devices may include electric incandescent lamps, heating devices, alternating current electric motors, transformer welding machines, and many others. They have a wide range of adjustment, which gives them a wide range of applications, including in everyday life.


Description and principle of operation

The operation of the device is based on regulating the turn-on delay of the triac when the mains voltage crosses zero. The triac is in the closed position at the beginning of the half-cycle. After the voltage of the positive half-wave increases, the capacitor is charged with a phase shift from the mains voltage.

This shift is determined by the resistance values ​​of resistors P1, R1, R2, and the capacitance of capacitor C1. When the threshold value is reached on the capacitor, the triac is turned on. It becomes conductive, allowing voltage to pass through, thereby bridging the circuit with resistors and capacitors. When the half-cycle passes through 0, the triac is turned off.

Then, when the capacitor is charged, it opens again with a negative voltage wave. Such operation of a triac is possible due to its structure. It has five layers of semiconductors with a control electrode. Which gives him the opportunity to swap the anode and cathode. To put it simply, it can be represented as two thyristors with a back-to-back connection.


Application area

Triac power regulators have found their application not only in everyday life, but also in many industries. In particular, they successfully replace cumbersome relay contact control circuits. They help set optimal currents in automatic welding lines, and in many other industries.

As for the use of these devices in everyday life, its use is very diverse. From regulating the voltage of incandescent lamps to regulating the fan speed. In a nutshell, the range is so diverse that it is not easy to describe.

Types of triac power regulators

Speaking about these devices, it should be noted that they all work on the same principle. Their main difference is the power for which they are designed. The second difference will be the control scheme. Some types of triac may require finer tuning of control signals. Control can be very diverse, from a capacitor and a pair of resistors to a modern microcontroller.

Scheme

Power regulators can use many different designs. The simplest circuit is considered to be the use of a variable resistor, and the most complex is a modern microcontroller. If you use it at home, then you can stick to the simplest one.

It will be enough for most needs. In addition to adjusting the light, the regulator is often used for. Those who like to do electrical engineering at home need to regulate the temperature of the soldering iron.

It is inconvenient to do this using variable resistors, plus there are large losses of electricity. The best solution would be to use a triac regulator.

How to assemble the regulator

For assembly, let's take the simplest circuit diagram. This circuit uses a triac VD2 - VTV 12-600V (600 - 800 V, 12 A), resistors: R1 -680 kOhm, R2 - 47 kOhm, R3 - 1.5 kOhm, R4 - 47 kOhm. Capacitors: C1 – 0.01 mF, C2 – 0.039 mF.

To assemble such a circuit with your own hands, you will need to do certain actions in the correct order:

  1. It is necessary to purchase all the parts from the list presented above.
  2. The second stage will be the development of a printed circuit board. When developing, it should be taken into account that some of the parts will be mounted mounted. And some of the parts will be installed directly into the board.
  3. Creating a board begins with drawing a picture with the location of parts and contact tracks between parts. Then the drawing is transferred to the board blank. When the drawing is transferred to the board, then everything proceeds according to a well-known method. Etching the board, drilling holes for parts, tinning the tracks on the board. Many people use modern computer programs such as Sprint Layout to obtain a board drawing, but if you don’t have them, it’s okay. In this case we have a small diagram. It can be done manually.
  4. When the board is ready, insert the necessary radio components into the prepared holes, shorten the length of the contacts with wire cutters to the required length and begin soldering. To do this, use a soldering iron to warm up the contact point on the board, apply solder to it, when the solder spreads over the surface at the contact point, remove the soldering iron and let the solder cool. In this case, all parts must remain in place and not move. When soldering, safety precautions should be observed. First of all, you need to protect yourself from burns; they can be caused by contact with a soldering iron, or splashes of hot solder or flux. You should have clothing that provides maximum protection to all areas of the body. And to protect your eyes, you need to wear safety glasses. The soldering area should be in a ventilated area, since corrosive gases may appear during operation.
  5. The final stage of assembly will be placing the resulting board into the box. Which box to choose will directly depend on the type of regulator you have. In the case of our scheme, a box the size of a plastic socket will be sufficient. A small number of parts, the largest of which is a variable resistor, take up little space and fit into a small space.
  6. The last step will be to check and configure the device. To do this, you will need a measuring device to monitor the voltage, and a device for the load, in our case a soldering iron. By rotating the regulator knob, you need to examine how smoothly the output voltage changes. If necessary, you can apply marks near the adjustment resistor.


Price

The market is replete with a large number of offers, with different price levels. The price of triac power regulators is primarily influenced by several parameters:

  1. Product power, the more powerful the power, the more expensive your device will be.
  2. The complexity of the control circuit, in the simplest circuits, the main cost is borne by triacs. In complex control circuits where microcontrollers are used, the price may increase due to them. They provide additional features, respectively, at a higher price. So the regulator is on a resistor with a voltage of 220 V, a power of 2500 W. costs 1200 rubles, and on a microcontroller with the same parameters 2450 rubles.
  3. Manufacturer's brand. Sometimes you can pay 50% more for a well-promoted brand.

Now you can find power regulators assembled according to various schemes. Each of them will have its own advantages and disadvantages. Modern regulators are divided into two types, microprocessor and analog. Analog regulators can be classified as economical class systems. They have been known since the times of the USSR, are easy to implement and cheap. Their most important disadvantage is the constant control of the owner or operator.

Let's give a simple example: you need to have a voltage of 170 V at the output. When you set this voltage, the supply voltage was 225 V, and now imagine that the input voltage has changed by 10 V, and the output voltage will change accordingly.

If the output voltage affects the process, problems may arise. In addition to the supply voltage drop, the output voltage can be affected by the parameters of the regulator itself. Since the capacitance of the capacitor changes over time, the variable resistor can be affected by environmental humidity, and it is impossible to achieve stable operation.

Microprocessor-based regulators do not have this problem. They implement feedback that allows you to quickly adjust the control signal.

One of the important aspects of long-term operation will be repair and service. Microprocessor regulators are complex products and require specialized service centers to repair them. Analog regulators are easier to repair. Any radio amateur can do it at home.

You can make the final choice on a triac power regulator after studying the conditions for its operation. When you do not need greater output accuracy, it is reasonable to give preference to an analog device, while saving money. When accuracy is required at the output, do not skimp, buy a microprocessor device.