To perform many types of work on wood, metal or other types of materials, it is not high speeds that are required, but good traction. It would be more correct to say - the moment. It is thanks to him that the planned work can be completed efficiently and with minimal power losses. For this purpose, DC (or commutator) motors are used as a drive device, in which the supply voltage is rectified by the unit itself. Then, to achieve the required performance characteristics, it is necessary to adjust the speed of the commutator motor without loss of power.

Features of speed control

It is important to know, what each engine consumes when rotating not only active, but also reactive power. In this case, the level of reactive power will be higher, which is due to the nature of the load. In this case, the task of designing devices for regulating the rotation speed of commutator motors is to reduce the difference between active and reactive powers. Therefore, such converters will be quite complex, and it is not easy to make them yourself.

You can construct only some semblance of a regulator with your own hands, but there is no point in talking about saving power. What is power? In electrical terms, it is the current drawn multiplied by the voltage. The result will give a certain value that includes active and reactive components. To isolate only the active one, that is, to reduce losses to zero, it is necessary to change the nature of the load to active. Only semiconductor resistors have these characteristics.

Hence, it is necessary to replace the inductance with a resistor, but this is impossible, because the engine will turn into something else and obviously will not set anything in motion. The goal of lossless regulation is to maintain torque, not power: it will still change. Only a converter can cope with such a task, which will control the speed by changing the duration of the opening pulse of thyristors or power transistors.

Generalized controller circuit

An example of a controller that implements the principle of controlling a motor without power loss is a thyristor converter. These are feedback proportional integrated circuits that provide strict regulation characteristics, ranging from acceleration and braking to reverse. The most effective is pulse-phase control: the repetition rate of the unlocking pulses is synchronized with the network frequency. This allows you to maintain torque without increasing losses in the reactive component. The generalized diagram can be represented in several blocks:

• power controlled rectifier;
• rectifier control unit or pulse-phase control circuit;
• tachogenerator feedback;
• current control unit in the motor windings.

Before delving into a more precise device and principle of regulation, it is necessary to decide on the type of commutator motor. The control scheme for its performance characteristics will depend on this.

Types of commutator motors

At least two types of commutator motors are known. The first includes devices with an armature and an excitation winding on the stator. The second includes devices with an armature and permanent magnets. It is also necessary to decide, for what purpose is it necessary to design a regulator:

Motor design

Structurally, the engine from the Indesit washing machine is simple, but when designing a controller to control its speed, it is necessary to take into account the parameters. Motors may have different characteristics, which is why the control will also change. The operating mode is also taken into account, which will determine the design of the converter. Structurally, the commutator motor consists from the following components:

• An armature, it has a winding laid in the grooves of the core.
• Collector, a mechanical rectifier of alternating mains voltage, through which it is transmitted to the winding.
• Stator with field winding. It is necessary to create a constant magnetic field in which the armature will rotate.

When the current in the motor circuit, connected according to the standard circuit, increases, the field winding is connected in series with the armature. With this inclusion, we also increase the magnetic field acting on the armature, which allows us to achieve linearity of characteristics. If the field remains unchanged, then it will be more difficult to obtain good dynamics, not to mention large power losses. It is better to use such motors at low speeds, since they are more convenient to control at small discrete movements.

By organizing separate control of the excitation and armature, it is possible to achieve high positioning accuracy of the motor shaft, but the control circuit will then become significantly more complicated. Therefore, we will take a closer look at the controller, which allows you to change the rotation speed from 0 to the maximum value, but without positioning. This might come in handy, if a full-fledged drilling machine with the ability to cut threads will be made from a washing machine engine.

Scheme selection

Having found out all the conditions under which the motor will be used, you can begin to manufacture a speed controller for the commutator motor. You should start by choosing a suitable scheme that will provide you with all the necessary characteristics and capabilities. You should remember them:

• Speed ​​regulation from 0 to maximum.
• Providing good torque at low speeds.
• Smooth speed control.

Looking at many schemes on the Internet, we can conclude that few people are creating such “units”. This is due to the complexity of the control principle, since it is necessary to organize the regulation of many parameters. Thyristor opening angle, control pulse duration, acceleration-deceleration time, torque rise rate. These functions are handled by a circuit on the controller that performs complex integral calculations and transformations. Let's consider one of the schemes, which is popular among self-taught craftsmen or those who simply want to put to good use an old motor from a washing machine.

All our criteria are met by a circuit for controlling the rotation speed of a brushed motor, assembled on a specialized TDA 1085 microcircuit. This is a completely ready-made driver for controlling motors that allow you to adjust the speed from 0 to the maximum value, ensuring torque maintenance through the use of a tachogenerator.

Design Features

The microcircuit is equipped with everything necessary for high-quality engine control in various speed modes, from braking to acceleration and rotation at maximum speed. Therefore, its use greatly simplifies the design, while simultaneously doing all universal drive, since you can choose any speed with a constant torque on the shaft and use it not only as a drive for a conveyor belt or drilling machine, but also for moving the table.

The characteristics of the microcircuit can be found on the official website. We will indicate the main features that will be required to construct the converter. These include: an integrated frequency-to-voltage conversion circuit, an acceleration generator, a soft starter, a Tacho signal processing unit, a current limiting module, etc. As you can see, the circuit is equipped with a number of protections that will ensure stable operation of the regulator in different modes.

The figure below shows a typical circuit diagram for connecting a microcircuit.

The scheme is simple, so it is quite reproducible with your own hands. There are some features that include limit values ​​and speed control method:

If you need to organize a motor reverse, then for this you will have to supplement the circuit with a starter that will switch the direction of the excitation winding. You will also need a zero speed control circuit to give permission for reverse. Not shown in the picture.

Control principle

When the rotation speed of the motor shaft is set by a resistor in output circuit 5, a sequence of pulses is formed at the output to unlock the triac by a certain angle. The speed of rotation is monitored by a tachogenerator, which occurs in digital format. The driver converts the received pulses into an analog voltage, which is why the shaft speed is stabilized at a single value, regardless of the load. If the voltage from the tachogenerator changes, the internal regulator will increase the level of the output control signal of the triac, which will lead to an increase in speed.

The microcircuit can control two linear accelerations, allowing you to achieve the dynamics required from the engine. One of them is installed on the Ramp 6 pin of the circuit. This regulator is used by washing machine manufacturers themselves, so it has all the advantages to be used for domestic purposes. This is ensured by the presence of the following blocks:

Usage similar scheme provides full control of the commutator motor in any mode. Thanks to forced acceleration control, it is possible to achieve the required acceleration speed to a given rotation speed. Such a regulator can be used for all modern washing machine motors used for other purposes.

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 pity 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

Designation	Type	Denomination	Quantity	Note	Shop	My notepad
T1	Triac	BT139-600	1			To notepad
T2	Dinistor		1			To notepad
VD	Diode bridge	KTs407A	1			To notepad
VD4	Rectifier diode	1N4148	1			To notepad
C2	Capacitor	220 uF x 4 V	1			To notepad
C1	Capacitor	100 nF x 160 V	1			To notepad
R1	Resistor	3.3 kOhm 0.5W	1			To notepad
R2	Resistor	330 Ohm 0.5W	1			To notepad
R3	Resistor	470 kOhm 0.125W	1			To notepad
R4	Resistor	200 Ohm 0.125W	1			To notepad
R5	Resistor	200 Ohm 0.125W	1			To notepad
V1	Optocoupler	PC817	2			To notepad
T3	Bipolar transistor	GT309G	1			To notepad
C2a	Capacitor	47 uF x 4 V	1

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

Not every modern drill or grinder is equipped with a factory speed regulator, and most often speed control is not provided at all. However, both grinders and drills are built on the basis of commutator motors, which allows each of their owners, even if they know how to handle a soldering iron, to make their own speed controller from available electronic components, either domestic or imported.

In this article we will look at the diagram and principle of operation of the simplest engine speed controller for a power tool, and the only condition is that the engine must be a commutator type - with characteristic lamellas on the rotor and brushes (which sometimes spark).

The above diagram contains a minimum of parts and is suitable for power tools up to 1.8 kW and above, for a drill or grinder. A similar circuit is used to regulate speed in automatic washing machines that have commutator high-speed motors, as well as in dimmers for incandescent lamps. Such circuits, in principle, will allow you to regulate the heating temperature of a soldering iron tip, an electric heater based on heating elements, etc.

The following electronic components will be required:

Constant resistor R1 - 6.8 kOhm, 5 W.

Variable resistor R2 - 2.2 kOhm, 2 W.

Constant resistor R3 - 51 Ohm, 0.125 W.

Film capacitor C1 - 2 µF 400 V.

Film capacitor C2 - 0.047 uF 400 volts.

Diodes VD1 and VD2 - for voltage up to 400 V, for current up to 1 A.

Thyristor VT1 - for the required current, for a reverse voltage of at least 400 volts.

The circuit is based on a thyristor. A thyristor is a semiconductor element with three terminals: anode, cathode, and control electrode. After a short pulse of positive polarity is applied to the control electrode of the thyristor, the thyristor turns into a diode and begins to conduct current until this current in its circuit is interrupted or changes direction.

After the current stops or when its direction changes, the thyristor will close and stop conducting current until the next short pulse is applied to the control electrode. Well, since the voltage in the household network is alternating sinusoidal, then each period of the network sinusoid the thyristor (as part of this circuit) will work strictly starting from the set moment (in the set phase), and the less the thyristor is open during each period, the lower the speed will be power tool, and the longer the thyristor is open, the higher the speed will be.

As you can see, the principle is simple. But when applied to a power tool with a commutator motor, the circuit works more cleverly, and we will talk about this later.

So, the network here includes in parallel: a measuring control circuit and a power circuit. The measuring circuit consists of constant and variable resistors R1 and R2, capacitor C1, and diode VD1. What is this chain for? This is a voltage divider. The voltage from the divider, and what is important, the back-EMF from the motor rotor, add up in antiphase, and form a pulse to open the thyristor. When the load is constant, then the open time of the thyristor is constant, therefore the speed is stabilized and constant.

As soon as the load on the tool, and therefore on the engine, increases, the value of the back-EMF decreases, since the speed decreases, which means the signal to the control electrode of the thyristor increases, and opening occurs with less delay, that is, the power supplied to the engine increases, increasing the dropped speed . This way the speed remains constant even under load.

As a result of the combined action of signals from the back-EMF and from the resistive divider, the load does not greatly affect the speed, but without a regulator this influence would be significant. Thus, using this circuit, stable speed control is achievable in each positive half-cycle of the network sinusoid. At medium and low rotation speeds this effect is more pronounced.

However, with increasing speed, that is, with increasing voltage removed from the variable resistor R2, the stability of maintaining a constant speed decreases.

In this case, it is better to provide a shunt button SA1 parallel to the thyristor. The function of diodes VD1 and VD2 is to ensure half-wave operation of the regulator, since the voltages from the divider and the rotor are compared only in the absence of current through the motor.

Capacitor C1 expands the control zone at low speeds, and capacitor C2 reduces sensitivity to interference from brush sparking. The thyristor needs to be highly sensitive so that a current of less than 100 μA can open it.

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