Three-phase analog power regulators. Three-phase voltage relay: diagram and connection features, price 3-phase thyristor power regulator

I present to your attention a three-phase power regulator on a microcontroller.

The device regulates the power in the active load connected by a triangle or a star, without the use of a neutral conductor. Designed for use with resistance furnaces, hot water boilers, three-phase heating elements and even incandescent lamps, subject to the condition of symmetrical load in the phases. Two modes of operation - regulation using the Bresenham algorithm, and the phase method of regulation. The device was conceived as as simple as possible, and available in repetition. Control from buttons or potentiometer, LED indicator of operating modes (optional), LED showing the status of the device.

Attention! Life-threatening voltage present! For experienced users!

The device diagram is divided into functional blocks for convenience. This makes it possible to make further changes and improvements to the design, without a radical redesign of the entire circuit. Each block will be described separately below.

power circuit

The author's version was built on powerful optothyristor modules MTOTO 80 - 12. Each module contains two counter-parallel eighty-amp optothyristors. Three modules are used, one for each phase. Control pulses come simultaneously to both power keys, but only the one to which the voltage is applied in direct polarity will open. The modules are interchangeable with thyristor or triac assemblies, or separate thyristors and triacs. Modular assemblies are easier to install, have an insulated substrate, and simplify the galvanic isolation of the control circuit. When using separate thyristors or triacs, you will need to install additional pulse transformers or optocouplers. You will also need to select the current-limiting resistors of optocouplers (R32-R34) for the copies you have. The microcontroller generates control pulses, which are amplified by composite transistors T7-T9. The pulses are modulated with a high frequency to reduce the current through the optocouplers, it also makes it possible to use small-sized pulse transformers (hereinafter referred to as TI). Optocouplers or TIs are powered by an unstabilized voltage of 15V.

Mandatory to install RC circuits in parallel with thyristors. In my version, these are PEV-10 39 Ohm resistors and MBM capacitors 0.1 microfarad 600v. The modules are mounted on a radiator, they heat up during operation. Load three-phase nichrome heater, maximum current 60A. There were no failures during the two years of operation.

Not shown in the diagram, but must be installed, a circuit breaker for the calculated load, it is also desirable to install a separate circuit breaker for the phases of the synchronization unit. The device is connected to a 3x380 volt network in compliance with the A-B-C phase sequence; if the sequence is incorrect, the device will not work. The neutral wire is needed to connect the power supply transformer if its primary winding is 220 volts. When using a 380 volt transformer, a neutral conductor is not needed.

Protective grounding of the device case is mandatory!

It does not need an explanation, two voltages are used - an unstabilized 15 volts and a stabilized 5 volts, the consumption in the author's version was up to 300mA, it largely depends on the LED indicator and the power elements used. You can use any available parts, there are no special requirements.

Contains three identical channels. Each channel is connected between two phases, i.e. the channels are connected by a triangle. At the moment of equality of the phase voltages (the point of intersection of the sinusoids), a pulse is formed that is used for synchronization in the MC. The details are not critical, but you need to adhere to the ratings for more accurate synchronization. If you have a two-beam oscilloscope, it is advisable to adjust the moment of pulse formation to the point of intersection of the sinusoids by selecting resistors R33, R40, R47. But this is not a prerequisite. The AOT 101 optocouplers used can be replaced with any similar and available ones, the only requirement for them is a high breakdown voltage, since it is the optocouplers that galvanically isolate the control unit from the network. You can find a simpler zero detector circuit, and assemble it, but taking into account the connection to phase-to-phase 380 V. It is highly desirable to use fuses, as shown in the diagram, it is also desirable to use a separate circuit breaker for this unit.

Control and display unit

This is the main block. The ATmega8 microcontroller sends control pulses to the thyristors and provides an indication of the operating modes. Works from the internal generator, clock 8 MHz. The fuses are shown below in the picture. Seven-segment LED indicator with a common anode, three digits. It is controlled through three anode keys T1-T3, the segments are switched by a shift register. It is possible not to set the indicator, register and related elements, if you do not need to set up the work. You can install any available type of indicators, but you will need to select current-limiting resistors in the segment circuit. LED HL1 shows the main status of the device.

Start and stop is carried out by the switch SB1. Closed state - Start, open - Stop. Power adjustment either from the Up, Down buttons, or from the setpoint R6, the choice is made through the menu. Inductor L, any small-sized, is needed for better filtering of the reference voltage of the ADC of the microcontroller. Capacitances C5, C6 need to be installed as close as possible to the power pins of the MK and the register, in my version they were soldered to the legs on top of the microcircuits. In conditions of high currents and strong interference, they are necessary for the reliable operation of the device.

Power regulator operation

Depending on the selected firmware, regulation will be carried out either by the phase-pulse method or by the method of skipping periods, the so-called Bresenham algorithm.

With pulse-phase regulation, the voltage on the load changes smoothly from almost zero to the maximum by changing the opening angle of the thyristors. The pulse is issued twice per period, simultaneously to both thyristors, but only the one to which the voltage is applied in direct polarity will be opened.

At low voltages (large opening angle), overshoot is possible due to the inaccuracy of the synchronization pulse at the moment of crossing the sinusoids. To eliminate this effect, the lower limit is set to 10 by default. Through the menu, if necessary, you can change it in the range from 0 to 99. In practice, this has never been required, but it all depends on the specific task. This method is suitable for adjusting the luminous flux of incandescent lamps, provided that they have the same power in each phase.

It is also important that the phase sequence of the network is correct A-B-C. To check, you can perform a test for the correct phase sequence when you turn on the device. To do this, when turning on the device, when the indicator displays the symbols - 0 - keep the button pressed menu , if the phasing is correct, the indicator will display the symbols AbC, if there is no ACb, and you need to swap any two phases.

If you release the button menu The device will enter the main mode of operation.

When using regulation by skipping periods, phasing is not required and the test is not included in the firmware. In this case, the thyristors open at the same time, you can think of them as a simple starter switching all three phases at once. The more power is needed at the load, the more times per unit time, the thyristors will be in a conducting state. This method is not suitable for incandescent lamps.

The device does not need to be configured.

When turned on, the settings are read from the non-volatile memory of the MK, if there are no values ​​in the memory, or they are incorrect, the default values ​​are set. Next, the MK checks for the presence of synchronization pulses and the state of the switch SB1. If SB1 in the open state does not issue control pulses, the indicator displays a message OFF, the HL1 LED flashes at a high frequency. If you close SB1, the current power reference will be displayed on the indicator, control pulses will be generated, the HL1 LED is constantly on. If at start-up or during operation control pulses are lost for more than 10 seconds, the indicator will display numbers 380 , the LED will blink at a low frequency, the thyristor control pulses will be removed. When the synchronization pulses appear, the device will return to work. This was done due to a poor network at the place of operation of the device, frequent interruptions and phase imbalances.

The menu contains four submenus, which can be switched with the button menu, if the button is not pressed for some time, the current set power level is displayed conditionally from 0 to 100. Power level is changed by buttons Up or Down, or, if enabled (default), potentiometer.

Long press button menu toggles the submenu.

Submenu 1 the indicator shows Grˉ this is the upper limit of power regulation, when you press the buttons Up or Down, the current value will be shown, it is possible to change it up or down, within the boundaries. The default value is 99.

Submenu 2 on the indicator Gr_ this is the lower limit of power regulation, everything is the same, the default value is 10.

Submenu 3 indicates whether the reference from potentiometer 1 is used - yes 0 - no. On the indicator 3-1 or 3-0 , selection by pressing the buttons Up or down. The default is used(1).

Submenu 4 on the indicator ZAP, when you press any of the buttons Up or down, the current values ​​will be written to the non-volatile memory of the MK. When recording, the inscription will flash once ZAP. The control limits will be recorded, whether the potentiometer is enabled and the current power value if it is set with the buttons and the potentiometer is not used.

Next press menu, switch to the main menu, the power value will be displayed. Also, a long press of the buttons will switch the menu to the main one.

It is possible not to use the seven-segment LED indicator if nothing needs to be changed, in which case everything will work, adjustable from 10 to 99 using a potentiometer. The status of the device will be shown by the HL1 LED. The indicator itself was needed at the debugging stage and for subsequent modernization. The plans are to build a regulator for an inductive load on this base, and make a soft starter for an asynchronous motor.

The printed circuit board was developed for the synchronization unit and for the control unit, but in the end, due to processing, the control unit was made hinged, on a breadboard, the printed circuit board is "as is" in the archive, the wiring of the seven-segment indicator is made for the indicator I have, if necessary, you can programmatically change the corresponding output segments. Part of the parts (RC circuits, resistors and diodes of the power circuit, power supply elements, buttons, potentiometer and LEDs) were mounted in the same way.

The archive contains the board of the control unit and the synchronization unit, in the sprint layout format, and the circuits in the Splan 7 format, there are also two firmware options for phase-pulse control and period skip control. The MK was sewn with a "five-wire" programmer under the control of the Uniprof program, you can download it on the author's website http://avr.nikolaew.org/

fuses are shown below.

Fuses are given for installation in this program, when using another - Remember that the included FUSE is FUSE without a checkmark!

Printed circuit boards are not optimal, and most likely, when repeated, they will have to be modified to fit the available parts, and the specific configuration and arrangement of elements (buttons, potentiometer, indicator, diodes and optocouplers). Also pay attention to the pads, if it is difficult to drill holes with a diameter of 0.5-0.7 mm, then before printing, you need to increase the size of the pads. The main requirement for the synchronization unit is to keep in mind that the voltage is high and there may be a breakdown on the surface of the textolite and on the surface of the parts, so it is advisable to use lead parts with a large distance between the leads. For the same reason, the bridges are made up of individual diodes. No need to save space and textolite! voltage at individual points of the synchronization board can reach 600 volts! After manufacturing, the board must be covered with electrical insulating varnish, preferably in two or three layers, in order to exclude dust breakdown.

The video is presented when working in the phase-pulse control mode, on the oscilloscope the signal from the current transformers included in two phases, the load is three incandescent lamps of 1 kW each. In the video, the layout of the device used for debugging.

Literature

• V.M. Yarov. "Power Sources of Electric Resistance Furnaces" textbook 1982
• A.V. Evstifeev "AVR microcontrollers of the Mega family, user manual" 2007

List of radio elements

Designation	Type	Denomination	Quantity	Note	Shop	My notepad
	Power scheme.
T1-T6	optocoupler	FOD8012	6			To notepad
T7-T9	bipolar transistor	KT972A	3			To notepad
C4-C6	Capacitor	0.1uF 600V	3	Paper		To notepad
R29-R31	Resistor	39 ohm	3			To notepad
R32-R34	Resistor	18 ohm	3			To notepad
R36-R38	Resistor	1 kOhm	3			To notepad
Rn	3-phase current consumer		1			To notepad
A, B, C	terminal clamp		3			To notepad
VR2	Linear Regulator	LM7805	1			To notepad
VD2	Diode		1			To notepad
VDS5	Diode bridge		1			To notepad
HL2	Light-emitting diode		1			To notepad
C9		470uF	1			To notepad
C10, C13	Capacitor	0.1uF	2			To notepad
C11	electrolytic capacitor	10 uF	1			To notepad
C12	electrolytic capacitor	100uF	1			To notepad
R36	Resistor	910 ohm	1			To notepad
FU1	Fuse		1			To notepad
Tr2	Transformer	220/380V - 15V	1			To notepad
	bipolar transistor	KT3102	6			To notepad
	optocoupler	AOT101AC	3			To notepad
VDS4-VDS6	Diode bridge		3	For voltage not less than 800 V		To notepad
VD4-VD6	rectifier diode	1N4007	3			To notepad
C4-C6	Capacitor	0.22uF	3			To notepad
R29, R30, R36, R37, R43, R44	Resistor	300 kOhm	6			To notepad
R31, R32, R38, R39, R45, R46	Resistor	120 kOhm	6			To notepad
R33, R40, R47, R50-R52	Resistor	22 kOhm	6			To notepad
R34, R41, R48	Resistor	100 kOhm	3			To notepad
R35, R42, R49	Resistor	300 ohm	3			To notepad
R53-R55	Resistor	5.1 kOhm	3			To notepad
	Fuse	100mA	6			To notepad
A, B, C	terminal clamp		3			To notepad
	Control and indication unit.
DD1	MK AVR 8-bit	ATmega8	1			To notepad
DD2	shift register	SN74LS595	1			To notepad
T1-T3	bipolar transistor

The digital power controller for a 3-phase AC motor is made using a special MC3PHAC chip from NXP Semiconductor. It generates 6 PWM signals for a 3 phase AC motor. The unit can be easily combined with a powerful 3-phase IGBT/MOSFET key drive. The board provides 6 PWM signals for the IPM or IGBT inverter, as well as a braking signal. The circuit works offline and does not require programming or coding.

Regulator circuit

Governing bodies

• PR1: Acceleration setting potentiometer
• PR2: Potentiometer for speed adjustment
• SW1: DIPX4 switch for frequency setting 60Hz/50Hz and output setting active low / active high
• SW2: Reset switch
• SW3: Start/stop motor
• SW4: change motor direction

Main settings

• Driver Power 7-15VDC
• Motor speed control potentiometer
• PWM frequency default 10.582 kHz (5.291 kHz - 164 kHz)

The MC3PHAC m/s is a monolithic intelligent controller designed specifically to meet the need for low cost variable speed 3-phase AC motor control systems. The device adapts and adjusts depending on its parameters. It contains all the active functions needed to implement the open loop control part. All of this makes the MC3PHAC ideal for applications requiring AC motor control support.

The MC3PHAC includes protective functions consisting of DC bus voltage monitoring and a system fault input that will immediately disable the PWM module when a system fault is detected.

All output signals are TTL level. Input for power supply 5-15 VDC, DC voltage on the bus must be between 1.75 - 4.75 volts, DIP switch is provided on the board for installation under motors with a frequency of 60 or 50 Hz, jumpers help set the polarity of the output PWM signal, that is, active low or active high, which allows you to use this board in any module, since the output can be set active low or high. The PR2 potentiometer helps regulate the speed of the motor. To change the base frequency, PWM off time, and other possible parameters, study the datasheet. Board files - archived

Speed ​​control. The motor synchronous frequency can be set in real time to any value from 1Hz to 128Hz by adjusting the PR2 potentiometer. The scaling factor is 25.6 Hz per volt. 24-bit digital filter processing to improve speed stability.

Acceleration control. Motor acceleration can be set in real time from 0.5Hz/s to 128Hz/s by adjusting potentiometer PR1. The scaling factor is 25.6 Hz/second per volt.

Protection. When a fault occurs, the MC3PHAC turns off the PWM immediately and waits until the fault condition is cleared before starting a timer to turn it back on. In offline mode, this timeout interval is set during the initialization phase by energizing the MUX_IN pin while the RETRY_TxD pin is driven low. Thus, the snooze time can be specified from 1 to 60 seconds with a scaling factor of 12 seconds per volt.

External Fault Monitoring. The FAULTIN pin accepts a digital signal indicating a fault detected by the external monitoring circuits. A high level on this input causes the PWM to turn off immediately. As soon as this input returns to logic low, the fault retry timer starts running and the PWM is re-enabled after reaching the programmed timeout value. Input pin 9 of the CN3 FLTIN connector must be high potential.

Voltage integrity monitoring(input signal pin 10 in cn3) in DC_BUS is monitored at 5.3 kHz (4.0 kHz if the PWM frequency is up to 15.9 kHz). In standalone mode, the thresholds are fixed at 4.47 volts (128% of nominal), and 1.75 volts (50% of nominal), where the nominal value is defined at 3.5 volts. As soon as the DC_BUS signal level returns to a value within the acceptable range, the failure retry timer starts running and the PWM is turned on again after the programmed timeout value is reached.

Regeneration. The saving process, by which the stored mechanical energy in the motor and load is transferred back to the drive electronics, usually occurs as a result of forced deceleration. In special cases where this process occurs frequently (e.g. elevator motor control systems), it turns on special functions to allow this energy to pass back into the AC grid. However, for most low-cost AC drives, this energy is stored in the DC bus capacitor by increasing its voltage. If this process is not set, the DC bus voltage can rise to dangerous levels, which can damage the bus capacitor or the transistors in the power inverter. MC3PHAC allows you to automate and stabilize this process.

Resistive braking. The DC_BUS pin is tracked at 5.3kHz (4.0kHz if the PWM frequency is up to 15.9kHz), and when the voltage reaches a certain threshold, the RBRAKE pin will take a high potential. This signal can be used to control a resistor brake placed through a DC bus capacitor, so mechanical energy from the motor will be dissipated as heat in the resistor. In standalone mode, the DC_BUS threshold required to assert the RBRAKE signal is fixed at 3.85 volts (110% of nominal), where nominal is defined as 3.5 volts.

PWM frequency selection. The MC3PHAC has four discrete PWM frequencies that can be changed dynamically as the motor rotates. This resistor can be a potentiometer or a fixed resistor within the range shown in the table. The PWM frequency is determined by applying voltage to the MUX_IN pin while the FREQ_RxD PWM pin is driven low.

Discuss the article POWER REGULATOR FOR 3 PHASE MOTOR

Such a simple, but at the same time very effective regulator, can be assembled by almost anyone who can hold a soldering iron in their hands and even slightly reads the circuits. Well, this site will help you fulfill your desire. The presented regulator regulates the power very smoothly without surges and dips.

Scheme of a simple triac regulator

Such a regulator can be used to control lighting with incandescent lamps, but also with LED ones, if you buy dimmable ones. The temperature of the soldering iron is easy to regulate. You can adjust the heating steplessly, change the speed of rotation of electric motors with a phase rotor, and many more where there is a place for such a useful little thing. If you have an old electric drill that does not have speed control, then by using this regulator, you will improve such a useful thing.
In the article, with the help of photographs, descriptions and the attached video, the entire manufacturing process is described in great detail, from the collection of parts to the testing of the finished product.

I say right away that if you are not friends with your neighbors, then you can not collect the chain C3 - R4. (Joke) It serves to protect against radio interference.
All parts can be bought in China on Aliexpress. Prices are two to ten times less than in our stores.
To make this device you will need:

• R1 - a resistor of about 20 Kom, with a power of 0.25 W;
• R2 - a potentiometer of approximately 500 kΩ, it is possible from 300 kΩ to 1 mΩ, but 470 kΩ is better;
• R3 - resistor approximately 3 Kom, 0.25 W;
• R4 - resistor 200-300 Ohm, 0.5 W;
• C1 and C2 - capacitors 0.05 uF, 400 V;
• C3 - 0.1 uF, 400 V;
• DB3 - dinistor, is in every energy-saving lamp;
• BT139-600, regulates the current 18 A or BT138-800, regulates the current 12 A - triacs, but you can take any others, depending on what load you need to regulate. A dinistor is also called a diac, a triac is a triac.
• The cooling radiator is selected from the value of the planned control power, but the more, the better. Without a radiator, you can regulate no more than 300 watts.
• Terminal blocks can be put any;
• Use the breadboard at your request, as long as everything is included.
• Well, without the device, as without hands. But the solder is better to use ours. It's more expensive, but much better. Good solder Chinese did not see.

Let's start assembling the regulator

First you need to think over the arrangement of parts so as to put as few jumpers as possible and solder less, then we very carefully check the compliance with the diagram, and then we solder all the connections.

After making sure that there are no errors and placing the product in a plastic case, you can test it by connecting it to the network.

The power regulators presented on this page are intended for switching 3-ph loads in automation systems, in production, at home. A three-phase power regulator is a complete device containing power thyristors, fuses, a radiator, a fan, and a control circuit in one housing. The three-phase regulator is intended for switching of loading at the same time on all 3 phases. Switching voltage variable ~200…480VAC 50 Hz. The control signal can be of different types - voltage 0-10VDC, current 4-20mA and is selected by a hardware jumper. The designation 60 Amp means that the power regulator can switch such a current in each phase. According to the type of switching, models are distinguished with switching when the voltage passes through zero (ZZ series) and with phase control (TP series). All power regulators can work with a 3-ph network without a neutral.

Features of the functioning of a three-phase power controller

During operation, the regulator heats up. Models with 30 and 45 amps use natural cooling, models with 60 amps and more use a fan. Regulators have a built-in overheating protection system. When the protection is activated, the output voltage is turned off. Three-phase voltage is connected to the terminals on the top of the device, from the bottom of the terminal for connecting the load power cable. The power regulator is mounted vertically on the wall with screws in the grooves of the radiator.

For all questions, please contact the managers of the Delta-kip online store in Moscow, you can contact us by the multi-channel phone number listed on our website.