RU2837783C1 - Stand for diagnostics of power boards, drivers and igbt transistors of cells of frequency-controlled drive of high-voltage motors - Google Patents

Abstract

FIELD: electric power industry.

SUBSTANCE: test bench for diagnostics of power supply boards, drivers and IGBT transistors of cells of frequency-controlled drive of high-voltage motors is a device having a rectangular housing. Housing houses a central processing unit connected to a power supply unit which is connected to an oscilloscope, a resistor and an ammeter. Central processing unit has an Arduino central processor with an ATmega8A programmable controller which outputs information on a display which forms an output rectangular signal and is connected to an encoder and a unit of dividers which control output voltages. Power supply unit contains the power supply unit itself, which is connected to the charging device, which is connected to the storage battery unit (accumulator battery), which provides the stand independent operation. and connected to the Arduino central processor, an oscilloscope, a resistor, an apmermeter and a voltage converter (DC/AC) from the battery constant voltage to the alternating voltage for the board power supply and control, the latter is connected to a voltage multiplier which converts voltage of 220 V to 500 V, connected through an ammeter to control currents through the transistor and power supply of the power supply board and drivers. On the front surface of the rectangular housing there are: switch SAC 1 "Output 500 V", ammeter display, display of programmable controller ATmega8A, encoder for menu control, oscilloscope display and HLG 1 "Transducer operation" light bulb, HLR 1 "Transducer alarm", as well as switch SAC 2 "Switching on converter". On one of the side surfaces there are connectors of 500 V DC output (J1) and power and driver boards (J2, J3, J4, J5, J6), and on the other – the battery charging connector (J7) for supply from the mains.

EFFECT: efficiency in diagnostics, simplicity of maintenance, as well as reduction of time spent on diagnostics and troubleshooting of VFD of high-voltage motor.

7 cl, 8 dwg

Description

The invention relates to electric power engineering, in particular to a stand for diagnosing power supply boards, drivers and IGBT transistors of frequency-controlled drive (VCD) cells of high-voltage motors, and is intended for diagnosing VCD cells involved in the soft start of main pumping units for pipeline oil transportation, and can also be used in other soft start devices.

With the increase in the number of frequency-driven equipment, the need for systematic monitoring of the equipment used has increased. Thus, it is necessary to diagnose power supply boards and drivers based on IGBT transistors and look for faults in advance.

An automated repair stand (BARS) is known from the prior art, consisting of a control electronic computer (EC) with software and hardware, which includes an internal local bus, at least no more than 10 input-output devices, an analog generator, a logic analyzer, a digital oscilloscope, built-in power supplies, a block of external connectors for connecting the device under test, characterized in that an intelligent controller is introduced into the hardware, containing a built-in 32-bit processor on a crystal (NIOS-processor), connected to the computer via a USB bus and to a random access memory (RAM) of the high-speed DDR memory type, as well as to a bus arbiter connected to the address port and the input-output port of the intelligent controller, connected to the internal local bus, wherein all internal devices of the hardware are controlled by the 32-bit processor on a crystal (NIOS-processor) via the internal local bus (RU 2421787 C2, G06F 11/22, 06/20/2011).

The main disadvantage of this technical solution is the impossibility of testing the power boards, drivers and IGBT transistors of the frequency-controlled drive cells of high-voltage motors.

A test bench for testing IGBT transistors and their gate drivers is known from the prior art, characterized in that it consists of a voltage stabilizer (1) providing power to a microcontroller (2), to which three buttons (3, 4, 5) are connected, a sound emitter (6) connected via a resistor (8) and an optocoupler (7), the power supply of which is carried out from the voltage stabilizer (9), a quartz resonator (10) with capacitors (11) and (12) connected to it, optocouplers (13) and (14) with resistors (15) and (16) connected in their input circuits, transistors (17), (18), (19), (20) forming a MOSFET bridge, a light-emitting diode (21), a counter-divider (22) with a transistor switch (23) connected to its input, an optocoupler (24) with a resistor (25) connected to its input, a light-emitting diode (26), a transistor switch (27) with a relay (28) connected in its circuit with contacts (29) for connecting a rectifier (30) with capacitors (31) and (32) connected in its circuit through a limiting resistor (33), an LED (34), a transistor switch (35) with a relay (36) connected in its circuit with a contact (37) shunting the resistor (33), an AC voltage switch (38) and an LED (39) (RU 186888 U1, G01R 31/02, 07.02.2019).

The proposed technical solution involves diagnostics of exclusively IGBT transistors of uninterruptible power supplies (UPS) based on the 2 Zilog Z86E0812PEC microcontroller. The test voltage is 24 V DC. At the same time, the given analog does not involve checking the power boards, drivers and IGBT transistors of the cells of the frequency-controlled drive of high-voltage motors, since it does not allow solving a number of problems in diagnostics:

- there are no necessary connectors and cable connections for connection to the board;

- the device cannot power all power and control circuits of the board;

- cannot clearly show a rectangular signal at the board output using an oscilloscope;

- does not have a clear and understandable interface.

When performing maintenance of soft starter cells, comprehensive diagnostics of power boards and drivers from an external source is not assumed.

It is possible to check the integrity and current flow only in the operating mode on the frequency drive control panels and by external inspection of the device. This approach does not allow to detect a number of faults of the power supply boards and control IGBT transistors (power bipolar transistor with an insulated gate).

The technical problem, which the declared technical solution is aimed at solving, is the development of a stand for diagnosing power supply boards, drivers and IGBT transistors of cells of a variable frequency drive of high-voltage motors, intended for diagnosing VFD cells and allowing for improved monitoring of the technical condition of the equipment.

The technical result of the claimed technical solution is to ensure the efficiency of diagnostics and ease of maintenance of the high-voltage motor VFD, as well as a reduction in the time spent on diagnostics and troubleshooting of the high-voltage motor VFD.

The technical result of the claimed invention is ensured by the fact that the test bench for diagnosing power supply boards, drivers and IGBT transistors of the cells of the variable frequency drive of high-voltage motors, according to the invention, is a device having a rectangular housing in which a central processor unit is installed, monitoring all circuits, connected to a power supply unit, which is connected to an oscilloscope for receiving and monitoring the incoming signal from the power supply boards, drivers and IGBT transistors, and is also connected to a series-connected resistor and the first ammeter for monitoring the current of the power supply board, wherein the central processor unit contains an ATmega8A microcontroller, programmable by the Arduino platform, generating an outgoing rectangular alternating electric signal, an encoder and a divider unit monitoring the output voltages, and the power supply unit contains a 220 V power supply unit connected to a charger, which is connected to a battery pack (BK), ensuring autonomous operation of the test bench and connected to the central processor unit, oscilloscope, resistor, the first ammeter, a DC/AC voltage converter and a voltage multiplier made according to the diode-capacitor-resistor circuit and providing the conversion of alternating voltage with a nominal value of 220 V into a direct voltage of 500 V, connected through the second ammeter to monitor the currents through the transistor and power the power supply board and drivers, while on the front surface of the rectangular case there are a SAC 1 key "500 V output" and an ammeter display in its central part, on the left side - a display of the programmable microcontroller "ATmega8A" and an encoder for menu control, and on the right side there is an oscilloscope display and, shifted downwards relative to the latter, HLG 1 "Converter operation", HLR 1 "Converter failure" lamps providing charging control, and the SAC 2 key "Converter on" for power supply, on one of the side surfaces of the case there are connectors for the 500 V DC output (J1) and the power supply boards and drivers (J2, J3, J4, J5, J6), and on the other - the battery charging connector (J7) for power supply from the network.

In addition, the body is made of ABS plastic.

In addition, the stand is designed with the ability to provide the formation of an outgoing rectangular alternating electrical signal on the J2 connector with the ability to subsequently connect to a standard location on the driver power board.

In addition, the stand is designed with the ability to ensure, when the encoder is pressed, the transmission of a pulse-width modulation signal to the power board, and then to the IGBT transistor with the ability to ensure sequential testing of four connected IGBT modules.

In addition, the stand is designed with the ability to ensure that the serviceability of the power supply board, driver and IGBT transistor is recorded in the presence of an alternating rectangular signal on the oscilloscope screen, and if the signal shape deviates from the rectangular one, their malfunction is detected.

In addition, the stand is designed with the ability to ensure testing of all power supply circuits, drivers and IGBT transistors.

In addition, the stand is designed as a portable device.

Thus, the combination of the presented features ensures the efficiency and simplicity of maintenance of the high-voltage motor VFD, as well as a reduction in the time spent on diagnostics and troubleshooting of the high-voltage motor VFD.

The claimed invention is shown in drawings 1-8.

Fig. 1 shows the block diagram of the stand.

Fig. 2 shows the block diagram of the stand.

Fig. 3 shows the shape of a rectangular signal.

Fig. 4 shows the operating principle of the stand.

Fig. 5 shows a diagram of the external appearance of the stand.

Fig. 6 shows the stand connectors.

Fig. 7 shows the battery charging connector J7.

Fig. 8 shows a photo of the external appearance of the stand.

List of positions used in the drawings:

1 - SAC 1 key "500 V output". Constant voltage on the IGBT transistor;

2 - display "ATmega8A";

3 - ammeter display;

4 - oscilloscope display;

5 - encoder for "Menu" control;

6 - HLG 1 lamp "Converter operation";

7 - HLR 1 lamp "Converter failure";

8 - SAC 2 key "Converter on";

9 - connector J1-500V DC output connector;

10 - connector J2 - connector of the power supply and driver board;

11 - connector J3 - connector of the power supply and driver board;

12 - connector 14 - connector for power supply and drivers board;

13 - connector J5 - connector of the power supply and driver board;

14 - connector 16 - connector for power supply and drivers board;

15 - connector J7 for battery charging.

List of abbreviations used in the drawings:

An IGBT transistor is a three-electrode power semiconductor device that combines two transistors in one semiconductor structure: a bipolar transistor (forming a power channel) and a field transistor (forming a control channel);

R _H - resistor;

АКБ - a battery pack that provides autonomous operation;

DC/AC - constant voltage converter;

AC battery for power supply and control of the board;

A - ammeter for monitoring the current consumption of the driver power supply board;

OSC - oscilloscope;

CPU - central processor that generates signals and controls all circuits.

The stand for diagnostics of power supply boards, drivers and IGBT transistors of frequency-controlled drive cells of high-voltage motors shown in Fig. 1-8 is a portable device on a microelectronic base, made in the form of a rectangular case (Fig. 8). The dimensions of the stand are 300×200×75 mm. These dimensions and the minimum weight, which is 2 kg, allow it to be used without rolled shelves and scaffolding.

The CPU unit is installed in the case, which monitors all circuits, connected to the power supply unit, which is connected to the oscilloscope (OSC), and is also connected to the series-connected resistor (R _H ) and the first ammeter (A). The oscilloscope is designed to receive and monitor the incoming signal via cables from the power supply boards, drivers and IGBT transistors. The ammeter is designed to monitor the current consumption of the power supply board (Fig. 4).

The CPU block contains an ATmega8A microcontroller, programmable by the Arduino platform, generating an outgoing rectangular alternating electrical signal, an encoder and a block of dividers that control the output voltages (Fig. 2).

The power supply unit contains a 220 V power supply unit connected to a charger, which is connected to a battery pack (B) that ensures autonomous operation of the stand and is connected to the central processor unit, an oscilloscope, a resistor, the first ammeter, a DC/AC voltage converter from the battery direct voltage to the alternating voltage for power supply and control of the board, and a voltage multiplier. The voltage multiplier is implemented according to a diode-capacitor-resistor circuit with the ability to convert an alternating voltage of 220 V to a direct voltage of 500 V and is connected through the second ammeter to monitor the currents through the transistor and power supply of the power supply board and drivers (Fig. 2). From the second ammeter, the signal goes to the "500 V Power Output" key 1, when pressed, the signal goes to the connector L 9 of the diagnostic stand. From the power connector, the cable goes to the standard connector on the driver power supply board, and then the chain goes to the emitter of the IGBT modules.

The power supply (Fig. 2) performs the function of converting the voltage from the 220 V AC network to 12 V DC with subsequent charging via a charger of high-capacity Li-ion batteries to maintain autonomous operation. Due to this, the stand can diagnose about 25 power boards, drivers and IGBT transistors of the cells of the frequency-controlled drive of high-voltage motors on one charge.

The stand is also powered from a 220 V network (connector J7 15) through a charger for battery power. Power is supplied to the stand by the SAC 2 key "Converter On" 8. To monitor the charging of the device, an alarm is displayed on the front panel of the stand in the form of lamps HLG 1 "Converter Operation" 6, HLR 1 "Converter Failure" 7 from the voltage converter.

On the front surface of the rectangular case there are located in its central part the SAC 1 key "500 V output" 1 and the display of the first ammeter 3. On the left side there is the display of the programmable microcontroller "ATmega8A" 2 and the encoder for menu control 5, on the right side there is the display of the oscilloscope 4 and the HLG 1 "Converter operation" 6, HLR 1 "Converter failure" 7 lamps shifted downwards relative to the latter, providing charging control, and the SAC 2 key "Converter on" 8 for power supply. On one of the side surfaces of the case there are connectors of the 500 V DC output (J1) 9 and the power supply and driver boards (J2, J3, J4, J5, J6) 10-14, and on the other there is the battery charging connector (J7) 15 for power supply from the 220 V network (Figs. 5-7).

In addition, the stand provides special measures and design solutions that ensure the safety of work, protection of the device itself and, what is very important, power boards and VFD drivers. This solution is implemented due to protection against minimum and maximum voltage on the voltage converter, as well as the use of built-in fuses on the drive control power board. It is worth noting that when applying increased voltage to the board (about 500 V), labor safety is ensured by using wires with PVC insulation, as well as a housing made of ABS plastic.

The operation of the stand is shown in the form of block diagrams presented in Fig. 1, 2, 4.

The operating principle of the stand is to supply voltage to the power supply board and the cell driver in the form of a generated outgoing alternating rectangular electrical signal. The signal is generated by the programmable ATmega8A microcontroller, according to a previously developed program code and installed in the stand case. The presence, level and shape of the output signal through the IGBT transistors will be used to judge the serviceability of the frequency-controlled drive cell. The serviceability of the power supply and driver boards is also checked by checking all power and control circuits on the board. These signals are also generated by the controller and compared with the nominal values specified in the code.

To diagnose the power board and drivers, you need to:

- if the battery is discharged, connect Connector J7 15 - Battery charging connector;

- connect the 12-pin cable from connectors J2, J3, J4, J5, J6 10-14 to the power and signal control connectors on the power and driver board;

- turn on the SAC 2 key “Converter on” 8 on the front panel of the stand;

- encoder for control "Menu" 5 select the board diagnostics menu;

By switching control button 5 clockwise, the serviceability or failure of the +- 4 V, +- 15 V and +- 24 V circuits will be displayed.

In case of successful testing, the reference values will match the measured boards. If there is a break in one of the chains on the board, the fault of the chains will be clearly displayed on the display.

To diagnose IGBT transistors, it is necessary:

- if the battery is discharged, connect Connector J7 15 - Battery charging connector;

- connect the 12-pin cable from connectors J2, J3, J4, J5, J6 10-14 to the power and signal connectors on the power and driver board;

- connect the 8-pin cable to the J1 9 connector "500 V DC output connector" of the stand. Apply 500 V DC power to one of the 4 connectors on the power and driver board;

- turn on the SAC 2 “Converter On” button 8 power supply on the front panel of the stand;

- use the “Menu” control button (encoder) 5 to select the IGBT transistor diagnostics menu.

By switching the control button 5 clockwise, the selected IGBT module will be displayed. With the key SAC 1 "Output 500V" 1 it is necessary to supply 500V power to the IGBT transistor.

The module's serviceability can be judged if the supplied signal has the same shape as the one coming out of the transistor on the oscilloscope screen, i.e. has a rectangular shape (Fig. 3). In the case of a short circuit on the transistor, interference and a sinusoidal oscillogram will be visible on the oscilloscope screen.

Next, you need to repeat this procedure with the remaining 3 modules.

During operation of the device, a constant voltage of about 500 V may be present at the output terminals.

The diagnostic stand simulates the operation of the VFD control cell, issuing a rectangular output signal to the board. This signal is formed on the J2 10 connector of the device, and then connected to the standard place on the driver power board by a cable with a plug.

The output signal is monitored via a built-in oscilloscope. The signal is picked up in a standard connector on the power and control board and connected via connector J3 11 of the diagnostic device, where the rectangular signal monitoring circuits are assembled (Fig. 3).

The signal is sent and checked as follows: the "Measuring waveform" item is selected in the controller menu. The device will prompt you to send a signal to one of the 4 connected IGBT modules. By pressing the encoder (the "Menu" button), the signal goes to the board via PWM modulation, and then to the transistor, checking 4 modules in turn, after which the diagnostics will be completed.

If we see a rectangular signal on the oscilloscope screen (Fig. 3), then we can conclude that the emitter and collector are closed correctly, the signal to the gate is sent correctly and the IGBT modules are in good working order. Otherwise, we can conclude that the equipment being diagnosed is faulty (board or transistor faulty).

Diagnostics of the board consists of checking all power and control circuits on the board (chains +/- 4 V; +/- 15 V; +/-24 V). These chains are formed by the board in normal operation. Failure of one of these chains may cause board failure or failure to control the IGBT module.

The nominal voltages of these chains are specified in the CPU code and must be compared with the measured values on the device display. From connectors J4-J5 12, 13, these nominal values are supplied to the board via an ammeter and a small load resistance. Current control is very important, since increased current consumption (more than 0.5 A) can indicate an internal short circuit in the board.

From the connector for monitoring the voltage circuits of the power supply board of the VFD power cell driver, the cable goes to the J6 14 connector of the diagnostic stand. The signal from the connector passes through the divider block and goes to the multichannel multiplexer. All collected values of measured voltages are converted into a language understandable to the controller and are displayed graphically on the screen.

The board is checked in the "Measuring voltage" menu. The display shows the current value on the left and the measured value on the right. The diagnostics are completed after each chain is checked.

The claimed technical solution was tested during diagnostics of power supply boards, drivers and IGBT transistors of Siemens variable frequency drive cells and showed that the proposed solution of the stand allows to check with 500 V voltage, as well as to control currents on the board. The implementation of the device based on the programmable microcontroller ATmega8A allows to perform diagnostics faster, as well as to display all active power supply chains clearly on the device screen and compare them with reference values. An undeniable advantage is also its compactness and ease of use. All control is carried out by one encoder. The stand menu includes several submenus. You can work with the device immediately after reading the simple user manual. The claimed invention will also be useful during equipment maintenance. In addition, before assembling the power cell circuit, they can be checked, based on the result of which a conclusion is made on putting the equipment into operation.

Claims (7)

1. A test bench for diagnosing power supply boards, drivers and IGBT transistors of variable frequency drive cells of high-voltage motors, characterized in that it is a device having a rectangular housing in which a central processor unit is installed, monitoring all circuits, connected to a power supply unit, which is connected to an oscilloscope for receiving and monitoring the incoming signal from the power supply boards, drivers and IGBT transistors, and is also connected to a series-connected resistor and the first ammeter for monitoring the current of the power supply board, wherein the central processor unit contains an ATmega8A microcontroller, programmable by the Arduino platform, generating an outgoing rectangular alternating electric signal, an encoder and a divider unit monitoring the output voltages, and the power supply unit contains a 220 V power supply unit connected to a charger, which is connected to a battery pack (BK), ensuring autonomous operation of the test bench and connected to the central processor unit, oscilloscope, resistor, first ammeter, DC/AC voltage converter and voltage multiplier, implemented according to the diode-capacitor-resistor circuit and providing the conversion of alternating voltage with a nominal value of 220 V into direct voltage of 500 V, connected through the second ammeter to monitor the currents through the transistor and power supply of the power supply board and drivers, while on the front surface of the rectangular case there are the SAC 1 key "500 V output" and the ammeter display in its central part, on the left side - the display of the programmable microcontroller "ATmega8A" and the encoder for menu control, and on the right side there is an oscilloscope display and the HLG 1 "Converter operation", HLR 1 "Converter failure" lamps shifted downwards relative to the latter, providing charging control, and the SAC 2 key "Converter on" for power supply, on one of the side surfaces of the case there are connectors for the 500 V DC output (J1) and the power supply boards and drivers (J2, J3, J4, J5, J6), and on the other - the battery charging connector (J7) for power supply from the network. 2. The stand according to item 1, characterized in that the body is made of ABS plastic. 3. The stand according to item 1, characterized in that it is designed with the ability to ensure the formation of an outgoing rectangular alternating electrical signal on connector J2 with the ability to subsequently connect to a standard location on the driver power supply board. 4. The stand according to item 1, characterized in that it is designed with the ability to ensure, when the encoder is pressed, the transmission of a pulse-width modulation signal to the power board, and then to the IGBT transistor with the ability to ensure sequential testing of four connected IGBT modules. 5. The stand according to item 1, characterized in that it is designed with the ability to ensure recording of the serviceability of the power board, driver and IGBT transistor in the presence of an alternating rectangular signal on the oscilloscope screen, and recording of their malfunction if the signal shape deviates from the rectangular one. 6. The stand according to item 1, characterized in that it is designed with the ability to ensure testing of all power supply circuits, drivers and IGBT transistors: +/- 4 V; +/- 15 V; +/- 24 V. 7. The stand according to item 1, characterized in that it is made in the form of a portable device.