Mitsubishi 

Speed ​​controller with feedback. Types and design of speed controllers for commutator motors. Increasing regulator power

When using an electric motor in tools, one of the serious problems is adjusting the speed of their rotation. If the speed is not high enough, then the tool is not effective enough.

If it is too high, then this leads not only to a significant waste of electrical energy, but also to possible burnout of the tool. If the rotation speed is too high, the operation of the tool may also become less predictable. How to fix it? For this purpose, it is customary to use a special rotation speed controller.

The motor for power tools and household appliances is usually one of 2 main types:

  1. Commutator motors.
  2. Asynchronous motors.

In the past, the second of these categories was most widespread. Nowadays, approximately 85% of motors used in electric tools, household or kitchen appliances are of the commutator type. This is explained by the fact that they are more compact, they are more powerful and the process of managing them is simpler.

The operation of any electric motor is based on a very simple principle: If you place a rectangular frame between the poles of a magnet, which can rotate around its axis, and pass a direct current through it, the frame will begin to rotate. The direction of rotation is determined according to the “right hand rule”.

This pattern can be used to operate a commutator motor.

The important point here is to connect the current to this frame. Since it rotates, special sliding contacts are used for this. After the frame rotates 180 degrees, the current through these contacts will flow in the opposite direction. Thus, the direction of rotation will remain the same. At the same time, smooth rotation will not work. To achieve this effect, it is customary to use several dozen frames.

Device


A commutator motor usually consists of a rotor (armature), stator, brushes and tachogenerator:

  1. Rotor- this is the rotating part, the stator is an external magnet.
  2. Brushes made of graphite- this is the main part of the sliding contacts, through which voltage is supplied to the rotating armature.
  3. Tachogenerator is a device that monitors rotation characteristics. In the event of a violation of the uniformity of movement, it adjusts the voltage supplied to the engine, thereby making it smoother.
  4. Stator may contain not one magnet, but, for example, 2 (2 pairs of poles). Also, instead of static magnets, electromagnet coils can be used here. Such a motor can operate on both direct and alternating current.

The ease of adjusting the speed of a commutator motor is determined by the fact that the rotation speed directly depends on the magnitude of the applied voltage.

In addition, an important feature is that the rotation axis can be directly attached to a rotating tool without the use of intermediate mechanisms.

If we talk about their classification, we can talk about:

  1. Brushed motors direct current.
  2. Brushed motors alternating current.

In this case, we are talking about what kind of current is used to power the electric motors.

Classification can also be made according to the principle of motor excitation. In a brushed motor design, electrical power is supplied to both the rotor and stator of the motor (if it uses electromagnets).

The difference lies in how these connections are organized.

Here it is customary to distinguish:

  • Parallel excitation.
  • Consistent excitation.
  • Parallel-sequential excitation.

Adjustment


Now let's talk about how you can regulate the speed of commutator motors. Due to the fact that the rotation speed of the motor simply depends on the amount of voltage supplied, any means of adjustment that are capable of performing this function are quite suitable for this.

Let's list a few of these options as examples:

  1. Laboratory autotransformer(LATR).
  2. Factory adjustment boards, used in household appliances (you can use in particular those used in mixers or vacuum cleaners).
  3. Buttons, used in the design of power tools.
  4. Household regulators lighting with smooth action.

However, all of the above methods have a very important flaw. Along with the decrease in speed, the engine power also decreases. In some cases, it can be stopped even just with your hand. In some cases, this may be acceptable, but in most cases, it is a serious obstacle.

A good option is to adjust the speed using a tachogenerator. It is usually installed at the factory. If there are deviations in the motor rotation speed, an already adjusted power supply corresponding to the required rotation speed is transmitted to the motor. If you integrate motor rotation control into this circuit, then there will be no loss of power.

How does this look constructively? The most common are rheostatic rotation control, and those made using semiconductors.

In the first case, we are talking about variable resistance with mechanical adjustment. It is connected in series to the commutator motor. The disadvantage is the additional heat generation and additional waste of battery life. With this adjustment method, there is a loss of engine rotation power. Is a cheap solution. Not applicable for sufficiently powerful motors for the reasons mentioned.

In the second case, when using semiconductors, the motor is controlled by applying certain pulses. The circuit can change the duration of such pulses, which in turn changes the rotation speed without loss of power.

How to make it yourself?

There are various options for adjustment schemes. Let us present one of them in more detail.

Here is how it works:

Initially, this device was developed to adjust the commutator motor in electric vehicles. We were talking about one where the supply voltage is 24 V, but this design is also applicable to other engines.

The weak point of the circuit, which was identified during testing of its operation, is its poor suitability at very high current values. This is due to some slowdown in the operation of the transistor elements of the circuit.

It is recommended that the current be no more than 70 A. There is no current or temperature protection in this circuit, so it is recommended to build in an ammeter and monitor the current visually. The switching frequency will be 5 kHz, it is determined by capacitor C2 with a capacity of 20 nf.

As the current changes, this frequency can change between 3 kHz and 5 kHz. Variable resistor R2 is used to regulate the current. When using an electric motor at home, it is recommended to use a standard type regulator.

At the same time, it is recommended to select the value of R1 in such a way as to correctly configure the operation of the regulator. From the output of the microcircuit, the control pulse goes to a push-pull amplifier using transistors KT815 and KT816, and then goes to the transistors.

The printed circuit board has a size of 50 by 50 mm and is made of single-sided fiberglass:

This diagram additionally shows 2 45 ohm resistors. This is done for the possible connection of a regular computer fan to cool the device. When using an electric motor as a load, it is necessary to block the circuit with a blocking (damper) diode, which in its characteristics corresponds to twice the load current and twice the supply voltage.

Operating the device in the absence of such a diode may lead to failure due to possible overheating. In this case, the diode will need to be placed on the heat sink. To do this, you can use a metal plate that has an area of ​​30 cm2.

Regulating switches work in such a way that the power losses on them are quite small. IN In the original design, a standard computer fan was used. To connect it, a limiting resistance of 100 Ohms and a supply voltage of 24 V were used.

The assembled device looks like this:



When manufacturing a power unit (in the lower figure), the wires must be connected in such a way that there is a minimum of bending of those conductors through which large currents pass. We see that the manufacture of such a device requires certain professional knowledge and skills. Perhaps in some cases it makes sense to use a purchased device.

Selection criteria and cost

In order to correctly choose the most suitable type of regulator, you need to have a good idea of ​​what types of such devices there are:

  1. Various types of control. Can be a vector or scalar control system. The former are used more often, while the latter are considered more reliable.
  2. Regulator power must correspond to the maximum possible engine power.
  3. By voltage It is convenient to choose a device that has the most universal properties.
  4. Frequency characteristics. The regulator that suits you should match the highest frequency that the motor uses.
  5. Other characteristics. Here we are talking about the length of the warranty period, dimensions and other characteristics.

Depending on the purpose and consumer properties, prices for regulators can vary significantly.

For the most part, they range from approximately 3.5 thousand rubles to 9 thousand:

  1. Speed ​​controller KA-18 ESC, designed for 1:10 scale models. Costs 6890 rubles.
  2. MEGA speed controller collector (moisture-proof). Costs 3605 rubles.
  3. Speed ​​controller for LaTrax 1:18 models. Its price is 5690 rubles.

65 rub.

Description:

Regulates the speed of the commutator motor (motor with brushes) without loss of power, regardless of the load. This module allows you to control speed from 0 to 20,000 rpm. (or the maximum declared by the manufacturer), while maintaining the moment of force on the electric motor shaft. The board has a power fuse and all the necessary terminals for connecting a 220V network, a motor and a tachometer. The regulator has found wide application for motors from automatic washing machines.

More details:

The module is a small board with all the necessary elements for wiring and built on a microcircuit TDA1085c. A prerequisite for connection is the presence of a tachometer (tachogenerator), which allows you to provide feedback from the electric motor to the microcircuit. When the engine is loaded, the speed begins to drop, which is detected by the tachometer, which commands the microcircuit to increase the voltage and vice versa, when the load weakens, the voltage to the engine drops. Thus, this design allows maintain constant power commutator motor when the rotor speed changes.

The The module fits well with the electric motor from an automatic washing machine. In combination of two devices, you can easily make it yourself: Wood lathe, Milling machine, Honey extractor, Lawn mower, Potter's wheel, Wood splitter, Emery, Drilling machine, Feed cutter and other devices where rotation of mechanisms is necessary.

There is an option for capacitor power supply:


The cost of this board 55.00 BYN.

Connection

To connect the commutator motor to the control board, you mustUnderstand the pinout of wires. A standard commutator motor has 3 groups of contacts: tachometer, brushes and stator winding. Rarely, there may also be a 4th group of thermal protection contacts (the wires are usually white).

Tachometer: located at the rear of the engine with wires coming out (smaller in cross-section than the others). The wires can be probed with a multimeter and may have a slight resistance.

Brushes: the wires communicate with each other and the engine commutator.

Winding: Wires have 2 or 3 terminals (with a middle point). The wires communicate with each other.

When connecting the commutator motor to a 220 Volt network:

We short-circuit one end of the brush and winding wires (or put a jumper in the terminal block), connect the other end of the wires to a 220V network. The direction of rotation of the motor will depend on which of the winding wires will be connected to the 220V network. If you need to change the direction of movement of the motor, place a jumper on another pair of winding-brush wires.

When connecting a brushed motor to the speed controller board:



We connect the wires with which the engine was connected to the 220V network to the terminal " M". To terminal " Taho" connect the tachometer. To terminal "L N" connect the mains power 220 Volts. Polarity doesn't matter.

The kit includes a switch (terminal S.A.). If a switch is not needed, install a jumper.

Settings

The board provides 3 types of settings:

Setting the speed smoothness;

Setting up the tachometer;

Setting the speed control range.

For operational reliability and correct setup, it is recommended to perform the setup in the following sequence:

1) Nadjusting the speed smoothness R1, which is responsible for the smooth speed of the commutator engine.

2) Setting up the tachometer performed by a trimming resistor R3, which allows you to eliminate jerking and jerking in engine operation when adjusting the rotation speed.

3) Setting the speed control range performed by a trimming resistor R2. The setting allows you to limit or increase the minimum speed of the commutator motor, even with the potentiometer turned down to the minimum.

Reverse connection

To connect the reverse switch, you need to remove the jumper in the motor (winding and brushes). The wires in the switch are separated by three pairs of wires, one of which has tinned ends. The pair with tinned ends is connected to terminal M. The remaining two pairs are connected to the winding and brushes. Which pair will be connected to the winding or brushes does not matter. The polarity of the connection does not matter.

A pair of wires for connecting to the engine tach sensor is green or black.

The reverse switch is not included in the standard package of the board and must be purchased separately.

Scheme for connecting the reverse to the board:

Board is customized and tested before sale!


Specifications

Contents of delivery

Power regulator board for TDA1085 - 1 pc.

Potentiometer with knob - 1 pc.

Switch - 1 pc.

Packaging with instructions - 1 pc.

Additional equipment

Set of wires with terminals - 5 pcs. +4 rub.

Reverse switch with wires on terminals - 1 set. +8 RUR

Installing the board into the case with all switches and wires (only connect to the motor) +35 rub.

Advantages:

1. The transformer power circuit ensures safe and reliable operation.
2. Before sale, all boards are configured and tested in operation.
3. The board's compact size allows it to be installed in any case.
4. High-quality installation of radio elements.
5. A factory-made board with a mask will provide protection from dust and corrosion.

Download description of the speed controller on the chip TDA1085CG

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Tags: collector motor speed controller 220v - 12v, do-it-yourself circuit on a TDA1085 chip buy Minsk, engine speed controller with power maintenance from an automatic washing machine, collector motor regulator for a honey extractor, do-it-yourself drilling or milling machine, do-it-yourself honey extractor, speed controller washing machine motor

When working with a power tool (electric drill, grinding device, etc.), it is desirable to be able to smoothly change its speed. But a simple decrease in the supply voltage leads to a decrease in the power developed by the tool. The proposed scheme (Fig. 1) uses feedback control of the motor current, as a result of which, as the load increases, the torque increases accordingly

On the shaft. The resistive-capacitive circuit R1-R2-C1 generates an adjustable reference voltage, which from the engine R2 enters the control electrode circuit of the thyristor VS1 and compensates for the residual back-EMF of the motor M1. If the engine rotation speed drops due to an increase in the load, its back-EMF also decreases . Due to this, in the next half-cycle of the mains voltage, the thyristor opens earlier due to the reference voltage. A corresponding increase in motor voltage leads to an increase in power at the motor shaft. When the speed increases and the load decreases, the described process occurs in reverse.

Setting up the device practically comes down to selecting resistance R1, so that at minimum speed the engine rotates smoothly, without jerking, and, at the same time, provides a full range of speed changes. It is possible that a small resistor will have to be connected to the lower terminal R2 in the circuit, limiting the minimum engine speed. If thyristor VS1 gets very hot, it needs to be installed on a heat sink.

A simplified version of the regulator is shown in Fig.. 2. If you clamp a screwdriver attachment into the chuck of an electric drill, you can use this attachment to tighten screws and self-tapping screws.

Literature

1 I. Semenov. Power regulator with feedback. - Radio Amateur, 1997, N12, P.21.

2 R.Graf. Electronic circuits 1300 examples - M Mir, 1989, P 395.

3. In Shcherbatyuk we drive the screws with an electric drill. - Radio Amateur, 1999 N9, S 23

A high-quality and reliable rotation speed controller for single-phase commutator electric motors can be made using common parts in literally 1 evening. This circuit has a built-in overload detection module, provides a soft start of the controlled motor and a motor rotation speed stabilizer. This unit operates with voltages of both 220 and 110 volts.

Regulator technical parameters

  • Supply voltage: 230 volts AC
  • regulation range: 5…99%
  • load voltage: 230 V / 12 A (2.5 kW with radiator)
  • maximum power without radiator 300 W
  • low noise level
  • speed stabilization
  • soft start
  • board dimensions: 50×60 mm

Schematic diagram


Scheme of motor regulator on a triac and U2008

The control system module circuit is based on a PWM pulse generator and a motor control triac - a classic circuit design for such devices. Elements D1 and R1 ensure that the supply voltage is limited to a value that is safe for powering the generator microcircuit. Capacitor C1 is responsible for filtering the supply voltage. Elements R3, R5 and P1 are a voltage divider with the ability to regulate it, which is used to set the amount of power supplied to the load. Thanks to the use of resistor R2, which is directly included in the input circuit to the m/s phase, the internal units are synchronized with the VT139 triac.


Printed circuit board

The following figure shows the arrangement of elements on a printed circuit board. During installation and startup, attention should be paid to ensuring safe operating conditions - the regulator is powered by a 220V network and its elements are directly connected to the phase.

Increasing regulator power

In the test version, a BT138/800 triac with a maximum current of 12 A was used, which makes it possible to control a load of more than 2 kW. If you need to control even larger load currents, we recommend installing the thyristor outside the board on a large heatsink. You should also remember to select the correct FUSE fuse depending on the load.

In addition to controlling the speed of electric motors, you can use the circuit to adjust the brightness of lamps without any modifications.

The regulator circuit, which is used to change the speed of rotation of the engine or fan, is designed to operate from an alternating current network at a voltage of 220 volts.

The motor, together with the power thyristor VS2, is connected to the diagonal of the diode bridge VD3, while the other receives an AC mains voltage of 220 volts. In addition, this thyristor carries out control with sufficiently wide pulses, due to which short circuit breaks, with which all commutator motors operate, do not affect the stable operation of the circuit.


The first thyristor is controlled by transistor VT1, connected according to a pulse generator circuit. As soon as the voltage on the capacitor becomes sufficient to open the first transistor, a positive pulse will be sent to the control terminal of the thyristor. The thyristor will open and now a long control pulse will appear on the second thyristor. And from it the voltage, which actually affects the speed, goes to the engine.

The rotational speed of the electric motor is adjusted by variable resistance R1. Since an inductive load is connected to the circuit of the second thyristor, spontaneous opening of the thyristor is possible, even in the absence of a control signal. Therefore, to block this, a diode VD2 is included in the circuit, which is connected in parallel to the L1 winding of the motor.

When setting up the engine speed controller circuit, it is advisable to use one, which can be used to measure the rotational speed of the electric motor, or a regular pointer voltmeter for alternating current, which is connected in parallel with the engine.

By selecting resistance R3, the voltage range is set from 90 to 220 volts. If the engine does not operate correctly at minimum speed, then it is necessary to reduce the value of resistor R2.

This circuit is well suited for adjusting fan speed depending on temperature.

It is used as a sensitive element. As a result of its heating, its resistance decreases, and therefore, at the output of the operational amplifier, on the contrary, the voltage increases and controls the fan speed through a field-effect transistor.

With variable resistance P1, you can set the lowest fan rotation speed at the lowest temperature, and with variable resistance P2, you can control the highest rotation speed at maximum temperature.

Under normal conditions, we set resistor P1 to the minimum engine speed. Then the sensor is heated and the desired fan speed is set with resistance P2.

The circuit controls the fan speed depending on the temperature readings, using a conventional negative temperature coefficient.

The circuit is so simple that it contains only three radio components: an adjustable voltage regulator LM317T and two resistances forming a voltage divider. One of the resistances is a negative TCR thermistor, and the other is a regular resistor. To simplify assembly, I provide a drawing of the printed circuit board below.

In order to save money, you can equip a standard angle grinder with a speed controller. Such a regulator for grinding housings of various electronic equipment is an indispensable tool in the arsenal of a radio amateur.

The U2008B microcircuit is a PWM speed controller for AC commutator motors. Manufactured by TELEFUNKEN, it can most often be seen in the control circuit of an electric drill, step saw, jigsaw, etc., and also works with motors from vacuum cleaners, allowing you to adjust the traction. The built-in soft start circuit significantly extends the life of the engines. Control circuits based on this chip can also be used to regulate power, for example, heaters.

All modern drills are produced with engine speed regulators built into them, but for sure, in the arsenal of every radio amateur there is an old Soviet drill, in which the change in speed was not intended, which sharply reduces the performance characteristics.

You can regulate the rotation speed of an asynchronous brushless motor by adjusting the frequency of the AC supply voltage. This scheme allows you to adjust the rotation speed in a fairly wide range - from 1000 to 4000 rpm.