PWM motor controller with feedback. Digital PWM speed controller of the collector motor. A simple DC motor control circuit

A high-quality and reliable rotation speed controller for single-phase collector motors can be made on common parts in just 1 evening. This circuit has a built-in overload detection module, provides a soft start to the controlled motor and a motor speed stabilizer. Such a unit works with a voltage of both 220 and 110 volts.

Regulator technical parameters

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

circuit diagram

The circuit of the control system module 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 the value of the generator microcircuit that is safe for power supply. Capacitor C1 is responsible for filtering the supply voltage. Elements R3, R5 and P1 are a voltage divider with the possibility of its regulation, 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 indoor units are synchronized with the VT139 triac.

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

Regulator power increase

In the test case, a triac BT138/800 with a maximum current of 12 A was used, which makes it possible to control a load of more than 2 kW. If it is necessary to control even higher load currents, we recommend installing the thyristor outside the board on a large radiator. You should also remember about right choice 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 the lamps without any alterations.

Any modern power tool or household appliance uses a commutator motor. This is due to their versatility, i.e., the ability to work both from a variable and from constant voltage. Another advantage is the effective starting torque.

However, high rpm commutator motor suits not all users. For smooth start-up and the ability to change the speed, a regulator was invented, which is quite possible to make with your own hands.

The principle of operation and varieties of collector motors

Each electric motor consists of a commutator, stator, rotor and brushes. The principle of its operation is quite simple:

In addition to the standard device, there are also:

Regulator device

There are many schemes of such devices in the world. Nevertheless, all of them can be divided into 2 groups: standard and modified products.

Standard device

Typical products are easy to manufacture idinistor, good reliability when changing engine speed. As a rule, such models are based on thyristor regulators. The principle of operation of such schemes is quite simple:

Thus, the speed of the collector motor is adjusted. In most cases, a similar scheme is used in foreign household vacuum cleaners. However, you should be aware that such a speed controller does not have feedback. Therefore, when the load changes, you will have to adjust the speed of the electric motor.

Changed Schemas

Of course, the standard device suits many lovers of speed controllers to “dig into” electronics. However, without progress and improvement of products, we would still live in the Stone Age. Therefore, more interesting schemes are constantly being invented, which many manufacturers are happy to use.

The most commonly used are rheostatic and integral regulators. As the name implies, the first option is based on a rheostat circuit. In the second case, an integral timer is used.

Rheostats are efficient in changing the number of revolutions of the collector motor. High efficiency is due to power transistors, which take part of the voltage. Thus, the current flow is reduced and the motor runs with less zeal.

Video: speed controller device with power maintenance

The main disadvantage of such a scheme is the large amount of heat generated. Therefore, for trouble-free operation, the regulator must be constantly cooled. Moreover, the cooling of the device should be intensive.

A different approach is implemented in the integral regulator, where the integral timer is responsible for the load. As a rule, transistors of almost any name are used in such circuits. This is due to the fact that the composition contains a microcircuit with large output current values.

If the load is less than 0.1 amperes, then all the voltage goes directly to the microcircuit, bypassing the transistors. However, for effective work The regulator requires a voltage of 12V at the gate. Therefore, the electrical circuit and the voltage of the power supply itself must correspond to this range.

Overview of typical circuits

It is possible to regulate the rotation of the shaft of a low-power electric motor by connecting a power resistor in series with the absence. However, this option has a very low efficiency and the inability to smoothly change the speed. To avoid such a nuisance, you should consider several regulator schemes that are used most often.

As you know, PWM has a constant amplitude of pulses. In addition, the amplitude is identical to the supply voltage. Therefore, the electric motor will not stop even when running at low speeds.

The second option is similar to the first. The only difference is that it uses operational amplifier. This component has a frequency of 500 Hz and is engaged in the development of pulses that have a triangular shape. Adjustment is also carried out by a variable resistor.

How to DIY

If you do not want to spend money on purchasing a finished device, you can make it yourself. Thus, you can not only save money, but also get a useful experience. So for making thyristor regulator required:

• soldering iron (to check the performance);
• wires;
• thyristor, capacitors and resistors;
• scheme.

As can be seen from the diagram, only 1 half-cycle is controlled by the regulator. However, for testing performance on a conventional soldering iron, this will be quite enough.

If knowledge on decoding the scheme is not enough, you can familiarize yourself with the text version:

The use of regulators allows more economical use of electric motors. In certain situations, such a device can be made independently. However, for more serious purposes (for example, control of heating equipment), it is better to purchase a ready-made model. Fortunately, there is a wide selection of such products on the market, and the price is quite democratic.

This homemade scheme Can be used as a speed controller for a 12V DC motor up to 5A rating or as a dimmer for 12V halogen and LED lamps up to 50W. Management is through pulse width modulation(PWM) at a pulse repetition rate of about 200 Hz. Naturally, the frequency can be changed, if necessary, by selecting for maximum stability and efficiency.

Most of these designs are going to much. Here we present a more advanced version that uses the 7555 timer, the driver for bipolar transistors and a powerful field MOSFET. This circuitry provides improved speed control and operates over a wide load range. This is indeed a very effective circuit and the cost of its parts when buying for self-assembly is quite low.

The circuit uses a 7555 Timer to create variable pulse widths around 200 Hz. It controls transistor Q3 (via transistors Q1 - Q2) which controls the speed of an electric motor or lights.

Another review on the topic of all sorts of things for homemade products. This time I will talk about the digital speed controller. The thing is interesting in its own way, but I wanted more.
For those interested, read on :)

Having in the household some low-voltage devices such as a small grinder, etc. I wanted to slightly increase their functional and aesthetic appearance. True, this did not work out, although I still hope to achieve my goal, perhaps another time, I’ll tell you about the thing itself today.
The manufacturer of this regulator is Maitech, or rather, this name is often found on all kinds of handkerchiefs and blocks for homemade products, although for some reason I did not come across the site of this company.

Due to the fact that I did not end up doing what I wanted, the review will be shorter than usual, but I will start, as always, with how it is sold and sent.
The envelope contained an ordinary ziplock bag.

The kit includes only a regulator with a variable resistor and a button, there is no hard packaging and instructions, but everything arrived intact and without damage.

There is a sticker on the back that replaces the instructions. In principle, more is not required for such a device.
The operating voltage range is 6-30 Volts and the maximum current is 8 Amps.

The appearance is quite good, dark "glass", dark gray plastic of the case, in the off state it seems generally black. By appearance off, nothing to complain about. A transport film was glued on the front.
Installation dimensions of the device:
Length 72mm (minimum case opening 75mm), width 40mm, depth excluding front panel 23mm (with front panel 24mm).
Front panel dimensions:
Length 42.5, width 80mm

A variable resistor comes with a handle, the handle is of course rough, but it will do for use.
The resistance of the resistor is 100KΩ, the adjustment dependence is linear.
As it turned out later, 100KΩ resistance gives a glitch. When powered by a pulsed power supply unit, it is impossible to set stable readings, the interference on the wires to the variable resistor affects, because of which the readings jump +\- 2 characters, but it would be fine to jump, along with this, the engine speed jumps.
The resistance of the resistor is high, the current is small and the wires collect all the noise around.
When powered by a linear PSU, this problem is completely absent.
The length of the wires to the resistor and the button is about 180mm.

Button, well, there's nothing special. Normally open contacts, mounting diameter 16mm, length 24mm, no illumination.
The button turns off the engine.
Those. when power is applied, the indicator turns on, the engine starts, pressing the button turns it off, the second press turns it on again.
When the engine is off, the indicator also does not light up.

Under the cover is the device board.
The power supply and motor connection contacts are brought out to the terminals.
The positive contacts of the connector are connected together, the power switch switches the negative wire of the engine.
The connection of the variable resistor and the button is detachable.
Everything looks neat. The capacitor leads are a bit crooked, but I think that this can be forgiven :)

I will hide further disassembly under the spoiler.

More

The indicator is quite large, the height of the digit is 14mm.
The dimensions of the board are 69x37mm.

The board is assembled neatly, there are traces of flux near the indicator contacts, but in general the board is clean.
The board contains: a reverse polarity protection diode, a 5 Volt stabilizer, a microcontroller, a 470 microfarad 35 Volt capacitor, power elements under a small radiator.
Places for installing additional connectors are also visible, their purpose is not clear.

I sketched a small block diagram, just for a rough understanding of what and how it is switched and how it is connected. The variable resistor is turned on with one foot to 5 volts, the second to the ground. Therefore, it can be safely replaced with a lower denomination. There are no connections to the unsoldered connector in the diagram.

The device uses a microcontroller manufactured by STMicroelectronics.
As far as I know, this microcontroller is used in a fairly large number of different devices, such as ammeters.

Power stabilizer, when operating at the maximum input voltage, heats up, but not very much.

Part of the heat from the power elements is removed to the copper polygons of the board, on the left you can see a large number of transitions from one side of the board to the other, which helps to remove heat.
Also, heat is removed with the help of a small radiator, which is pressed against the power elements from above. This placement of the heatsink seems a little doubtful to me, since the heat is removed through the plastic of the case and such a heatsink does not help much.
There is no paste between the power elements and the radiator, I recommend removing the radiator and smearing it with paste, at least a little but it will get better.

A transistor is used in the power section, the channel resistance is 3.3mOhm, the maximum current is 161 Amperes, but the maximum voltage is only 30 Volts, so I would recommend limiting the input at 25-27 Volts. When operating at near-maximum currents, there is a slight heating.
A diode is also located nearby, which dampens the current surges from the self-induction of the motor.
10 amps, 45 volts are applied here. There are no questions about the diode.

First inclusion. It so happened that I carried out the tests even before removing the protective film, because in these photos it is still there.
The indicator is contrasting, moderately bright, reads perfectly.

At first I decided to try on small loads and got the first disappointment.
No, I have no complaints about the manufacturer and the store, I just hoped that such a relatively expensive device would have engine speed stabilization.
Alas, this is just an adjustable PWM, the indicator displays% filling from 0 to 100%.
The regulator didn’t even notice the small motor, the day it is a completely ridiculous load current :)

Attentive readers must have paid attention to the cross-section of the wires with which I connected the power to the regulator.
Yes, then I decided to approach the issue more globally and connected a more powerful engine.
Of course, it is noticeably more powerful than the regulator, but at idle its current is about 5 amperes, which made it possible to check the regulator at modes closer to the maximum.
The regulator behaved perfectly, by the way, I forgot to indicate that when turned on, the regulator smoothly increases the PWM filling from zero to the set value, ensuring smooth acceleration, while the indicator immediately shows the set value, and not like on frequency drives, where the real current is displayed.
The regulator did not fail, warmed up a little, but not critical.

Since the regulator is pulsed, I decided, just for fun, to poke around with an oscilloscope and see what happens at the gate of the power transistor in different modes.
The PWM frequency is about 15 kHz and does not change during operation. The engine starts at approximately 10% fill.

Initially, I planned to put the regulator in my old (rather already ancient) power supply for small power tools (more on that some other time). in theory, it should have become instead of the front panel, and the speed controller should have been located on the back, I didn’t plan to put a button (fortunately, when turned on, the device immediately switches to the on mode).
It had to be nice and neat.

But further disappointment awaited me.
1. Although the indicator was a little smaller in size than the front panel insert, it was worse that it did not fit in depth, resting against the racks for connecting the halves of the case.
and if the plastic of the indicator housing could be cut off, then it would not matter, since the regulator board interfered further.
2. But even if I would have solved the first question, there was a second problem, I completely forgot how my power supply was made. The fact is that the regulator breaks the minus supply, and I have a relay for reverse, turning on and forcing the engine to stop, and a control circuit for all this. And with their alteration, everything turned out to be much more difficult :(

If the regulator was with speed stabilization, then I would still get confused and redo the control and reverse circuit, or redo the regulator for switching + power. And so it is possible and I will redo it, but already without enthusiasm and now I don’t know when.
Maybe someone is interested, a photo of the insides of my PSU, it was going to be about 13-15 years ago, almost all the time it worked without problems, once I had to replace the relay.

Summary.
pros
The device is fully functional.
Neat appearance.
Quality build
The kit includes everything you need.

Minuses.
Incorrect operation from switching power supplies.
Power transistor without voltage margin
With such a modest functionality, the price is too high (but everything is relative here).

My opinion. If you close your eyes to the price of the device, then in itself it is quite good, and it looks neat and works fine. Yes, there is a problem of not very good noise immunity, I think that it is not difficult to solve it, but it is a little frustrating. In addition, I recommend not to exceed the input voltage above 25-27 Volts.
More frustrating is the fact that I looked quite a lot of options for all kinds of ready-made regulators, but nowhere do they offer a solution with speed stabilization. Perhaps someone will ask why I do this. I will explain how a grinding machine with stabilization fell into the hands, it is much more pleasant to work than usual.

That's all, I hope it was interesting :)

The product was provided for writing a review by the store. The review is published in accordance with clause 18 of the Site Rules.

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Smooth operation of the engine, without jerks and power surges is the key to its durability. To control these indicators, an electric motor speed controller for 220V, 12 V and 24 V is used, all these frequency converters can be made by hand or you can buy a ready-made unit.

Why do you need a speed controller

The engine speed controller, frequency converter is a device for powerful transistor, which is necessary in order to invert the voltage, as well as provide a smooth stop and start of the induction motor using PWM. PWM - wide-pulse control of electrical devices. It is used to create a specific sinusoid of alternating and direct current.

Photo - powerful regulator for asynchronous motor

The simplest example of a converter is a conventional voltage regulator. But the device under discussion has a much larger range of work and power.

Frequency converters are used in any device that is powered by electrical energy. ESCs provide extremely precise electrical motor control so that the engine speed can be changed up or down, keep the RPM at the right level and protect the instruments from revving. In this case, the electric motor uses only the energy necessary for operation, instead of running it at full power.

Photo - DC motor speed controller

Why do you need a speed controller for an asynchronous electric motor:

1. To save electricity. By controlling the speed of the motor, the smoothness of its start and stop, the strength and frequency of revolutions, you can achieve significant savings in personal funds. As an example, a 20% reduction in speed can result in energy savings of 50%.
2. The frequency converter can be used to control process temperature, pressure or without a separate controller;
3. No additional controller required for soft start;
4. Significantly reduced maintenance costs.

The device is often used for welding machine(mainly for semi-automatic machines), an electric stove, a number of household appliances (vacuum cleaner, sewing machine, radio, washing machine), home heater, various ship models, etc.

Photo - PWM speed controller

The principle of operation of the speed controller

The speed controller is a device consisting of the following three main subsystems:

1. AC motor;
2. Main drive controller;
3. Drive and additional parts.

When the AC motor is started at full power, the current is transferred with the full power of the load, this is repeated 7-8 times. This current bends the motor windings and generates heat that will be released for a long time. This can significantly reduce the durability of the engine. In other words, the converter is a kind of step inverter that provides double energy conversion.

Photo - regulator diagram for a collector motor

Depending on the input voltage, the frequency controller of the speed of a three-phase or single-phase electric motor rectifies the current of 220 or 380 volts. This action is carried out using a rectifying diode, which is located at the energy input. Next, the current is filtered using capacitors. Next, PWM is formed, the electrical circuit is responsible for this. Now the windings of the induction motor are ready to transmit the pulse signal and integrate them to the desired sinusoid. Even with a microelectric motor, these signals are issued, in the truest sense of the word, in batches.

Photo - sine wave of normal operation of the electric motor

How to choose a regulator

There are several characteristics by which you need to choose a speed controller for a car, a machine tool electric motor, and household needs:

1. Control type. For a collector electric motor, there are controllers with a vector or scalar control system. The former are more commonly used, but the latter are considered more reliable;
2. Power. This is one of the most important factors to select an electrical frequency converter. It is necessary to select a frequency converter with a power that corresponds to the maximum allowable on the protected device. But for a low-voltage motor, it is better to choose a regulator more powerful than the allowable Watt value;
3. Voltage. Naturally, everything is individual here, but if possible, you need to buy a speed controller for an electric motor, in which circuit diagram has a wide range of allowable voltages;
4. Frequency range. Frequency conversion is the main task of this device, so try to choose a model that will best suit your needs. Let's say 1000 Hertz will be enough for a manual router;
5. For other features. These are the warranty period, the number of inputs, the size (there is a special attachment for desktop machines and hand tools).

In this case, you also need to understand that there is a so-called universal rotation controller. This is a frequency converter for brushless motors.

Photo - controller diagram for brushless motors

This circuit has two parts - one is logical, where the microcontroller is located on the microcircuit, and the second is power. Basically, such an electrical circuit is used for a powerful electric motor.

Video: motor speed controller with SHIRO V2

How to make a homemade engine speed controller

You can make a simple triac motor speed controller, its circuit is presented below, and the price consists only of parts sold in any electrical store.

For work, we need a powerful triac like BT138-600, it is advised by the magazine of radio engineering.

Photo - do-it-yourself speed controller diagram

In the described scheme, the revolutions will be regulated using the potentiometer P1. Parameter P1 determines the phase of the incoming pulse signal, which in turn opens the triac. Such a scheme can be used both in the field and in the home. You can use this regulator for sewing machines, fans, bench drills.

The principle of operation is simple: at the moment when the engine slows down a little, its inductance drops, and this increases the voltage in R2-P1 and C3, which in turn leads to a longer opening of the triac.

A thyristor feedback controller works a little differently. It provides reverse stroke energy into the energy system, which is very economical and profitable. This electronic device involves the inclusion in electrical circuit powerful thyristor. His schema looks like this:

Here, to supply direct current and rectification, a control signal generator, an amplifier, a thyristor, and a speed stabilization circuit are required.