Regulating the rotation speed of the commutator motor. Speed ​​controller for commutator electric motors

Adjusting the speed of the washing machine engine may be necessary for any home DIYer who decides to adapt a part from a used machine.

Simply connecting the washing machine engine to the power supply does not do much good, since it immediately produces maximum speed, but many homemade appliances require increasing or decreasing speed, preferably without loss of power. In this publication we will talk about how to connect the motor from the washing machine, and how to make a speed controller for it.

Let's connect first

Before adjusting the speed of the washing machine engine, it must be connected correctly. The commutator motors from automatic washing machines have several outputs, and many novice DIYers confuse them and cannot understand how to connect. Let's talk about everything in order, and at the same time check the operation of the electric motor, because there is a possibility that it is completely faulty.

For your information! Tachometers having two outputs can be easily checked with an ohmmeter. But similar parts with three outputs do not ring in any direction.

• Next, we take one wire coming from the collector and connect it to one of the coil wires.
• We connect the second wire of the collector and the second wire of the coil to a 220 V network.
• If we need to change the direction of rotation of the armature, then we simply swap the places of the connected wires, namely, the first wire of the collector and the first wire of the coil are connected to the network, and the second wires are connected to each other.
• We mark the wires of the coil, tachometer and collector with labels so as not to confuse them and perform a test run of the engine.

If the test run was successful, namely, the engine smoothly picked up speed without jamming or jerking, and the brushes did not spark, you can begin connecting the washing machine motor through the speed controller. There are many diagrams for connecting a motor through a regulator, as well as diagrams for the regulator itself; let’s consider two options.

Connect via voltage regulator

The simplest option for adjusting the electric motor of a washing machine is to use any voltage regulator (dimmer, drill trigger, etc.). The meaning of the adjustment is that the maximum voltage is first applied to the engine, and it rotates at maximum speed. By turning the dimmer switch, we reduce the voltage, and the engine accordingly begins to reduce speed. The connection diagram is as follows:

• We connect one coil wire to one armature wire;
• connect the second wire of the coil to the network;
• we connect the second armature wire to the dimmer, and connect the second output of the dimmer to the network;
• We test run the engine.

We check how the engine operates at minimum power. You can see that even at minimum power the idle speed is impressive, but you just need to lean a wooden block against the rotating axle and the engine immediately stops. What is the conclusion? And the conclusion is that this method of adjusting the speed of the washing machine electric motor leads to a catastrophic loss of power when the voltage decreases, which is unacceptable if you are going to make some kind of homemade product out of the engine.

Important! When starting the washing machine engine, follow safety precautions. Be sure to secure the engine before starting, and do not touch the rotating elements with your hands.

Initially, we set the task of learning to regulate the speed of the washing machine engine with our own hands without loss or with minimal loss of power, but is this possible? It is quite possible that the connection diagram will simply become somewhat more complicated.

Via microcircuit

It's time to remember about the tachometer and its outputs, which we found on the engine, but set aside for the time being. It is the tachometer that will help us connect the washing machine motor and regulate its speed without loss of power. The tachometer itself cannot control the engine, it is only an intermediary. The actual control must be carried out through a microcircuit that is connected to the motor tachometer, winding and armature and is powered from a 220 V network. You can see the circuit diagram in the figure below.

What happens to the motor when we connect it to the network through this chip? And the following happens: we can start the engine with our own hands at maximum speed, or we can turn the special toggle switch to reduce the speed. We give a sudden load to the engine by placing a wooden block under the rotating pulley. The speed drops for a split second, but then recovers again, despite the load.

The fact is that the tachometer detects a decrease in speed due to the load that has arisen and immediately sends a signal about this to the control board. The microcircuit, having received the signal, automatically adds power, thus leveling the engine speed. The homemade dream, as they say, has come true. If you have such a connection diagram, you can make a wood splitter and many other useful things from the washing machine motor.

To summarize our story, we will answer another reasonable question that the reader may have: where can I get such a board? You can assemble it based on the diagram and list of parts that we attach to this article, or you can order it ready-made from specialists. Fortunately, there are enough offers on this matter on the Internet. You need to look for the TDA 1085 circuit.

The motor from a washing machine, which is great for homemade items, has too high speeds and a short lifespan at maximum speeds. Therefore, I use a simple homemade speed controller (without loss of power). The scheme was tested and showed excellent results. The speed is adjustable from approximately 600 to max.

The potentiometer is electrically isolated from the network, which increases the safety of using the regulator.

The triac must be placed on the radiator.

Almost any optocoupler (2 pcs), but EL814 has 2 counter LEDs inside, and is suitable for this circuit.

A high-voltage transistor can be installed, for example, IRF740 (from a computer's power supply), but it would be a shame to install such a powerful transistor in a low-current circuit. Transistors 1N60, 13003, KT940 work well.

Instead of the KTs407 bridge, a 1N4007 bridge, or any one with >300V, and a current of >100mA, is quite suitable.

Signet in .lay5 format. The signet is drawn “View from the M2 side (soldering)”, so When outputting to a printer, it must be mirrored. Color M2 = black, background = white, do not print other colors. The outline of the board (for cutting) is made on the M2 side, and will indicate the boundaries of the board after etching. It should be removed before sealing parts. A drawing of parts from the mounting side has been added to the signet for transfer to the signet. It then takes on a beautiful and finished look.

Adjustment from 600 rpm is suitable for most homemade products, but for special cases a circuit with a germanium transistor is proposed. The minimum speed was reduced to 200.

The minimum speed was 200 rpm (170-210, the electronic tachometer does not measure well at low speeds), the T3 transistor was installed GT309, it is direct conduction, and there are many of them. If you put MP39, 40, 41, P13, 14, 15, then the speed should decrease further, but I no longer see the need. The main thing is that such transistors are like dirt, unlike MP37 (see forum).

Soft start works great, True, the motor shaft is empty, but due to the load on the shaft during start-up, I will select R5 if necessary.

R5 = 0-3k3 depending on the load;; R6 = 18 Ohm - 51 Ohm - depending on the triac, I don’t have this resistor now;; R4 = 3k - 10k - T3 protection;; RP1 = 2k-10k - speed controller, connected to the network, protection from the operator's mains voltage is required!!!. There are potentiometers with a plastic axis, it is advisable to use them!!!This is a big drawback of this scheme, and if there is no great need for low speeds, I advise you to use V17 (from 600 rpm).

C2 = soft start, = delay time for turning on the motor;; R5 = charge C2, = charge curve slope, = motor acceleration time;; R7 - C2 discharge time for the next soft start cycle (at 51k this is approximately 2-3 seconds)

List of radioelements

Based on the powerful triac BT138-600, you can assemble a circuit for an AC motor speed controller. This circuit is designed to regulate the rotation speed of electric motors of drilling machines, fans, vacuum cleaners, grinders, etc. The motor speed can be adjusted by changing the resistance of potentiometer P1. Parameter P1 determines the phase of the trigger pulse, which opens the triac. The circuit also performs a stabilization function, which maintains engine speed even under heavy load.

For example, when the motor of a drilling machine slows down due to increased metal resistance, the EMF of the motor also decreases. This leads to an increase in voltage in R2-P1 and C3 causing the triac to open for a longer time, and the speed increases accordingly.

Regulator for DC motor

The simplest and most popular method of adjusting the rotation speed of a DC motor is based on the use of pulse width modulation ( PWM or PWM ). In this case, the supply voltage is supplied to the motor in the form of pulses. The repetition rate of the pulses remains constant, but their duration can change - so the speed (power) also changes.

To generate a PWM signal, you can take a circuit based on the NE555 chip. The simplest circuit of a DC motor speed controller is shown in the figure:

Here VT1 is an n-type field-effect transistor capable of withstanding the maximum motor current at a given voltage and shaft load. VCC1 is from 5 to 16 V, VCC2 is greater than or equal to VCC1. The frequency of the PWM signal can be calculated using the formula:

F = 1.44/(R1*C1), [Hz]

Where R1 is in ohms, C1 is in farads.

With the values ​​indicated in the diagram above, the frequency of the PWM signal will be equal to:

F = 1.44/(50000*0.0000001) = 290 Hz.

It is worth noting that even modern devices, including those with high control power, are based on precisely such circuits. Naturally, using more powerful elements that can withstand higher currents.

Each of us has some kind of electrical appliance at home that has been working in the house for more than one year. But over time, the power of the technology weakens and does not fulfill its intended purpose. This is when you should pay attention to the insides of the equipment. Mostly problems arise with the electric motor, which is responsible for the functionality of the equipment. Then you should turn your attention to a device that regulates engine speed without reducing its power.

Types of engines

The speed control with power maintenance is an invention that will breathe new life into an electrical appliance, and it will work like a newly purchased product. But it is worth remembering that engines come in different formats and each has its own maximum performance.

The engines have different characteristics. This means that this or that technique operates at different speeds of the shaft that triggers the mechanism. The motor may be:

1. single-phase,
2. two-phase,
3. three-phase.

Mostly three-phase electric motors are found in factories or large factories. At home, single-phase and two-phase are used. This electricity is enough to operate household appliances.

Power speed regulator

Work principles

A 220 V electric motor speed controller without loss of power is used to maintain the initial set shaft speed. This is one of the basic principles of this device, which is called a frequency regulator.

With its help, the electrical device operates at the set engine speed and does not reduce it. The engine speed controller also affects the cooling and ventilation of the motor. With the help of power, the speed is set, which can be either raised or reduced.

Many people have asked the question of how to reduce the speed of a 220 V electric motor. But this procedure is quite simple. One has only to change the frequency of the supply voltage, which will significantly reduce the performance of the motor shaft. You can also change the power supply to the motor by activating its coils. Electrical control is closely related to the magnetic field and motor slip. For such actions, they mainly use an autotransformer and household regulators, which reduce the speed of this mechanism. But it is also worth remembering that engine power will decrease.

Shaft rotation

Engines are divided into:

1. asynchronous,
2. collector

The speed controller of an asynchronous electric motor depends on the current connection to the mechanism. The essence of the operation of an asynchronous motor depends on the magnetic coils through which the frame passes. It rotates on sliding contacts. And when, when turning, it turns 180 degrees, then through these contacts the connection will flow in the opposite direction. This way the rotation will remain the same. But with this action the desired effect will not be obtained. It will come into force after a couple of dozen frames of this type are added to the mechanism.

The commutator motor is used very often. Its operation is simple, since the passed current passes directly - because of this, the power of the electric motor is not lost, and the mechanism consumes less electricity.

The washing machine motor also needs power adjustment. For this purpose, special boards were made that cope with their job: the engine speed control board from a washing machine has multifunctional use, since its use reduces the voltage, but does not lose rotation power.

The circuit of this board has been verified. All you have to do is install diode bridges and select an optocoupler for the LED. In this case, you still need to put a triac on the radiator. Basically, engine adjustment starts at 1000 rpm.

If you are not satisfied with the power regulator and its functionality is lacking, you can make or improve the mechanism. To do this, you need to take into account the current strength, which should not exceed 70 A, and heat transfer during use. Therefore, an ammeter can be installed to adjust the circuit. The frequency will be small and will be determined by capacitor C2.

Next, you should configure the regulator and its frequency. When outputting, this pulse will go out through a push-pull amplifier using transistors. You can also make 2 resistors that will serve as an output for the computer's cooling system. To prevent the circuit from burning out, a special blocker is required, which will serve as double the current value. So this mechanism will work for a long time and in the required volume. Power regulating devices will provide your electrical appliances with many years of service without special costs.

You have to deal with the problem of adjusting the speed of an electric motor quite often: this is work with various power tools, sewing machine drives, and other electrical appliances in production and at home. Regulating the speed by lowering the supply voltage often makes no sense: the engine speed decreases sharply, it loses power and stops. Therefore, the best option for regulating the engine speed is to change the voltage using load current feedback.

In most cases, power tools and other equipment use universal commutator motors with series excitation. They work equally well on both AC and DC power. The peculiarity of the operation of a commutator electric motor is that during commutation of the armature windings, when the commutator lamellas are opened, pulses of self-inductive back-EMF occur. They are equal in amplitude to the supply pulses, but in phase they are opposite to them. The angle of displacement of the back-EMF depends both on the external characteristics of the motor and on the load and other factors.

The harmful effect of back-EMF leads to sparking on the commutator, as well as loss of engine power and additional heating of its windings. Some of the back-EMF is suppressed by capacitors that bypass the brush assembly.

Let's look at the processes that occur in the feedback control mode, using the example of a universal circuit ( see fig. 1). The reference voltage, which determines the rotation speed of the electric motor, is formed by the resistive-capacitive circuit P12-KZ-S2. As the load increases, the rotation speed drops, and its torque also decreases. At the same time, the back-EMF that occurs in the engine and is applied between the cathode and the control electrode of thyristor VS1 also decreases. This leads to a change in voltage at the control electrode of the thyristor, which increases in proportion to how the back EMF decreases.

The additional voltage on the control electrode of the thyristor causes it to turn on at a smaller phase angle (cut-off angle) and supply more current to the motor, which thus compensates for the decrease in rotation speed as the load increases. This leads to the presence of a pulse voltage balance on the control electrode of the thyristor, which is composed of the supply voltage and the self-induction voltage of the motor.

If necessary, it is possible to use switch SA1 to switch to power supply using full voltage, without using adjustment. Particular attention must be paid to selecting a thyristor based on the minimum switching current, as this will ensure better stabilization of the motor rotation speed.

Second switching circuit ( see fig.2) is designed to work with more powerful motors that are used in sanders, woodworking machines and drills. The principle of regulation remains the same. The thyristor in this circuit must be installed on a radiator with an area of ​​at least 25 sq.cm.

If it is necessary to obtain very low rotation speeds or when used for low-power motors, you can use a circuit using an IC ( see fig. 3). It is powered by 12V DC. In case of power supply from a higher voltage, it is necessary to use a parametric stabilizer with a stabilization voltage no higher than 15V.

Speed ​​control is carried out by changing the average voltage of the pulses that are supplied to the engine. With the help of such pulses, it is possible to effectively regulate very low rotation speeds, since they seem to “push” the engine rotor. When the rotation speed increases, the engine operates normally.

Quite a simple scheme ( see fig. 4) is intended for use on a toy railroad line. It will allow you to avoid emergency situations and provide new opportunities for managing trains. The incandescent lamp, located in the external circuit, protects and serves to signal a short circuit on the line, while limiting the output current.

If it is necessary to regulate the speed of engines with a large torque on the shaft (for example, in an electric winch), a full-wave bridge circuit shown in Fig. 5. Its significant difference from previous schemes, where only one half-wave of the supply voltage operates, is the provision of full power to the engine.

Quenching resistor R2 and diodes VD2 and VD6 are used to supply power to the trigger circuit. The phase delay in opening the thyristors is ensured by charging capacitor C1 through resistors R3 and R4 from a voltage source, the level of which depends on the zener diode VD8. After charging the capacitor C1 to the operating threshold of the unijunction transistor VT1, the latter opens and starts the thyristor whose anode has a positive voltage. After the capacitor discharges, the unijunction transistor turns off. The value of resistor R5 is determined by the desired feedback depth and the type of motor. To calculate its value, the formula is used:

where Im is the effective value of the maximum load current for a given motor type.

The proposed schemes are easily repeated, but require the selection of certain elements depending on the characteristics of the electric motor used (unfortunately, it is almost impossible to find electric motors that are identical in all respects, even within the same series).