WO2021237806A1

WO2021237806A1 - Driving circuit and power electronic device

Info

Publication number: WO2021237806A1
Application number: PCT/CN2020/095435
Authority: WO
Inventors: 曾金芳
Original assignee: 深圳市汇川技术股份有限公司
Priority date: 2020-05-27
Filing date: 2020-06-10
Publication date: 2021-12-02
Also published as: CN111614244A

Abstract

A driving circuit and a power electronic device. The driving circuit is for use and applicable in the power electronic device. The power electronic device comprises a buffer circuit connected in series on a direct-current bus and used for buffering the current at the moment an entire machine is powered on. The buffering circuit consists of a buffer switch and a buffer resistor connected in parallel. The buffer switch comprises a bus thyristor connected in parallel to the buffer resistor. The driving circuit is used for driving the bus thyristor. The driving circuit comprises an isolation unit and a high-voltage switch unit, where the isolation unit is connected at an input end to an output end of a control unit of the power electronic device and is connected at an output end to a control end of the high-voltage switching unit, and, the high-voltage switch unit is connected at an input end to an anode of the bus thyristor and is connected with a gate electrode of the bus thyristor and then connected to a reference ground. The driving circuit is highly integrated, inexpensive, and applicable in power electric devices at the 380-480 V level.

Description

Drive circuit and power electronic equipment

Technical field

The present invention relates to the technical field of frequency converter drive, and more specifically, to a drive circuit and power electronic equipment.

Background technique

For voltage-type inverters that use diode uncontrollable rectification, electrolytic capacitors are required for energy storage and filtering on the DC bus. Since electrolytic capacitors have the characteristic that the voltage cannot be changed suddenly, the input impulse current at the moment of power-on of the whole machine will be very large. This large impulse current Will adversely affect the rectifier bridge and bus capacitance, so this current needs to be limited. In existing inverters, this function is generally achieved by adding a buffer circuit (ie, a soft start circuit). The buffer circuit can be connected in series on the positive DC bus, as shown in Figure 1, or in series. Negative DC bus, as shown in Figure 2.

The snubber circuit generally uses a circuit form of a snubber switch T and a snubber resistor D in parallel, and the snubber switch generally uses device types such as relays, contactors, and thyristors. When the thyristor is selected as the buffer switch on the bus, a driving circuit for driving the thyristor of the bus needs to be added. Since the thyristor is a current-type drive device, its drive circuit is more complicated than the relay drive circuit. In addition, the peak value of the grid voltage will be all added to the bus thyristor at the moment of power-on, and this voltage will also be added to the thyristor Therefore, the bus thyristor drive circuit used in this occasion must also be able to withstand the high voltage at the moment of power-on of the whole machine. This makes the above-mentioned drive circuit need to use high-voltage resistant switching devices, that is, the bus-bar SCR drive circuit needs to have current-type driving and at the same time need to withstand high voltage.

The existing bus thyristor drive circuit generally has a dedicated drive optocoupler using a thyristor, or an optocoupler plus a high-voltage MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor, metal-oxide semiconductor field effect transistor) drive scheme , Or use discrete devices to build more complex drive circuits and so on.

However, the above-mentioned SCR dedicated drive optocoupler is only for 220V voltage level applications, and the device withstand voltage is only 800V. It can only be used on 220V level inverters, and cannot be used on 380V-480V voltage level inverters (otherwise it is easy to make mistakes). Trigger), and the price of this type of optocoupler is relatively high; in the optocoupler + high-voltage MOSFET scheme, the high-voltage MOSFET is more expensive; the circuit built with discrete devices has many resistors, capacitors and other discrete components, which occupy a large volume of the printed circuit board , The reliability is not good.

technical problem

The embodiment of the present invention aims at the above-mentioned bus SCR drive circuit, which has components with a withstand voltage of only 800V, which cannot be used in the inverter with a voltage level of 380V-480V. The special drive optocoupler for SCR is expensive; or, high-voltage MOSFET High cost; or, there are many discrete device circuit components, large printed circuit board volume occupied, and poor reliability. A drive circuit and electronic power equipment are provided.

Technical solutions

The technical solution of the embodiment of the present invention to solve the above technical problems is to provide a drive circuit applied to power electronic equipment, the power electronic equipment includes a DC bus connected in series, for buffering the current at the moment of power-on of the whole machine The buffer circuit is composed of a buffer switch and a buffer resistor in parallel, the buffer switch includes a bus thyristor connected in parallel with the buffer resistor, the drive circuit is used to drive the bus thyristor, the The drive circuit includes an isolation unit and a high-voltage switch unit, among which:

The input end of the isolation unit is connected to the output end of the control unit of the power electronic device, the output end of the isolation unit is connected to the control end of the high voltage switch unit, and the input end of the high voltage switch unit is connected to the bus controllable The anode of silicon, the output terminal of the high-voltage switch unit and the gate stage of the bus thyristor are connected to the reference ground;

At the moment when the power electronic device is powered on, the high-voltage switch unit remains in the off state. At this time, the bus thyristor is in the off state, and the peak value of the input voltage at the moment of power-on is simultaneously applied to the input terminal of the high-voltage switch unit And the output terminal, the power electronic device charges the bus capacitor through the buffer resistor;

When the bus voltage of the power electronic device rises to a preset value, the isolation unit controls the high-voltage switch unit to conduct according to the thyristor control signal input by the control unit, so that the high-voltage switch unit is The gate of the bus thyristor outputs a trigger current to control the bus thyristor to conduct, so that the power electronic device completes power-on buffering.

Preferably, the high-voltage switch unit includes a current-limiting resistor and a one-way thyristor, and the anode of the one-way thyristor forms the input terminal of the high-voltage switch unit through the current-limiting resistor, and is connected to the input terminal of the high-voltage switch unit. The anode of the bus thyristor; the cathode of the one-way thyristor constitutes the output terminal of the high-voltage switch unit, and is connected to the reference ground after being connected to the gate of the bus thyristor; the one-way thyristor The gate stage of the thyristor constitutes the control terminal of the high-voltage switch unit and is connected to the output terminal of the isolation unit.

Preferably, when the power supply of the power electronic device is a three-phase alternating current with a voltage level of 380V-480V, the withstand voltage level of the one-way thyristor is greater than 1200V.

Preferably, the isolation unit adopts an optocoupler isolation circuit, the optocoupler isolation circuit includes an isolation optocoupler primary loop and an isolation optocoupler secondary loop, and the output terminal of the control unit is connected to the isolation optocoupler. A side loop, the isolation optocoupler secondary loop is connected to the control terminal of the high-voltage switch unit.

Preferably, the isolated optocoupler secondary loop includes a photosensitive device, a first voltage divider resistor, and a second voltage divider resistor, and the input end of the photosensitive device forms the power supply end of the isolated optocoupler secondary loop connected to the first An external power supply, the output terminal of the photosensitive device is connected to the reference ground via the first voltage dividing resistor and the second voltage dividing resistor, and the connection point of the first voltage dividing resistor and the second voltage dividing resistor constitutes the The output terminal of the isolation unit is connected to the control terminal of the high-voltage switch unit.

Preferably, the isolated optocoupler primary loop includes a light-emitting device, a third voltage dividing resistor, and a fourth voltage dividing resistor. The input end of the light-emitting device and one end of the third voltage dividing resistor are connected together to form the The power supply end of the isolated optocoupler primary loop is connected to the second external power supply, the output end of the light-emitting device is connected to the other end of the third voltage divider resistor and then connected to one end of the four voltage divider resistor, so The other end of the fourth voltage dividing resistor constitutes the input end of the isolation unit and is connected to the output end of the control unit of the power electronic device.

The embodiment of the present invention also provides a power electronic device, which includes a buffer circuit connected in series on a DC bus and used to buffer the current at the moment of power-on of the whole machine. The buffer circuit is composed of a buffer switch and a buffer resistor in parallel. The buffer switch includes a bus thyristor connected in parallel with the buffer resistor, and the power electronic device further includes the above-mentioned driving circuit, and the bus thyristor is driven by the driving circuit.

Preferably, the DC bus includes a positive DC bus and a negative DC bus;

The buffer circuit is connected in series on the negative DC bus; or, the buffer circuit is connected in series on the positive DC bus.

Beneficial effect

The drive circuit and power electronic equipment of the embodiment of the present invention, through the cooperation of the high-voltage switch unit and the isolation unit, generates a drive signal according to the output signal of the control unit of the power electronic equipment to drive the bus thyristor switch, compared to the dedicated thyristor By driving the optocoupler, the embodiment of the present invention can improve the withstand voltage and can be applied to power electronic equipment with voltage levels of 380V-480V. Compared with the solution of optocoupler + high voltage MOSFET, the embodiment of the present invention can significantly reduce the cost; In the discrete device construction scheme, the embodiment of the present invention reduces the occupation of the printed circuit board area and improves the reliability.

Description of the drawings

Figure 1 is a circuit topology diagram of an existing inverter;

Figure 2 is a circuit topology diagram of another inverter;

Fig. 3 is a schematic diagram of a driving circuit provided by an embodiment of the present invention;

Fig. 4 is a schematic diagram of a driving circuit provided by an embodiment of the present invention applied to a frequency converter.

Embodiments of the present invention

In order to make the objectives, technical solutions, and advantages of the present invention clearer, the following further describes the present invention in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, but not used to limit the present invention.

As shown in Figures 3 and 4, they are schematic diagrams of the drive circuit provided by the first embodiment of the present invention. The drive circuit can be applied to power electronic equipment such as frequency converters, drives, and converters. On the bus bar, a buffer circuit used to buffer the current at the moment of power-on of the whole machine. The buffer circuit is composed of a buffer switch and a buffer resistor in parallel, and the buffer switch includes a bus thyristor T connected in parallel with the buffer resistor R. The driving circuit of the embodiment of the present invention is used to drive the above-mentioned bus thyristor T, and the driving circuit of this embodiment includes a high-voltage switch unit 31 and an isolation unit 32.

The input terminal SCR_Control of the isolation unit 32 is connected to the output terminal of the control unit of the power electronic device, and the output terminal of the isolation unit 32 is connected to the control terminal of the high-voltage switch unit 31; the input terminal SCR_A of the high-voltage switch unit 31 is connected to the bus bar. The anode of the thyristor T, and the output terminal SCR_G of the high-voltage switch unit 31 and the gate of the bus thyristor T are connected in common and then connected to the reference ground GND_SCR.

At the moment when the power electronic equipment is powered on, the high-voltage switch unit 31 remains in the off state, so that the bus thyristor T is in the off state, and the input voltage peak value at the moment of power-on is simultaneously applied to the input terminal SCR_A and the output terminal SCR_G of the high-voltage switch unit 31 In between, the power electronic device charges the bus capacitor through the buffer resistor R; when the bus voltage of the power electronic device rises to a preset value, the control unit inputs the thyristor control signal to the input terminal SCR_Control of the isolation unit 32, and the isolation unit 32 According to the SCR control signal, the high-voltage switch unit 31 is controlled to be turned on, so that the high-voltage switch unit 31 outputs a trigger current to the gate of the bus thyristor T, and controls the bus thyristor to turn on T, so that the power electronic equipment completes power-on buffering .

The above-mentioned driving circuit isolates and outputs the control signal output by the control unit of the power electronic device through the isolation unit 32, and the high-voltage switch unit 31 generates a driving signal according to the isolation signal output by the isolation unit 32 to drive the bus thyristor switch. Compared with the thyristor dedicated drive optocoupler, the above-mentioned drive circuit can be applied to power electronic equipment with a voltage level of 380V-480V by increasing the withstand voltage level of the high-voltage switch unit 31; compared to the optocoupler + high-voltage MOSFET solution, The embodiment of the present invention can significantly reduce the cost; compared with the use of discrete devices to build a solution, the embodiment of the present invention reduces the area occupied by the printed circuit board and improves the reliability.

In an embodiment of the present invention, the above-mentioned high-voltage switch unit 31 includes a current-limiting resistor R1 and a unidirectional thyristor T1, and the anode of the unidirectional thyristor T1 forms the input terminal SCR_A of the high-voltage switch unit 31 through the current-limiting resistor R1. , And the anode of the bus SCR T is connected, so as to provide the DC voltage to the anode of the one-way SCR T1 through the DC bus of the power electronic equipment, and it will be generated in the current-limiting resistor R1 when the one-way SCR T1 is turned on The trigger current that causes the one-way thyristor T1 to turn on. The cathode of the unidirectional thyristor T1 forms the output terminal SCR_G of the high-voltage switch unit 31, and is connected to the reference ground GND_SCR after being connected to the gate stage of the bus thyristor T. The gate stage of the one-way thyristor T1 constitutes the control terminal of the high-voltage switch unit 31 and is connected to the output terminal of the isolation unit 32.

When the output terminal of the isolation unit 32 outputs higher than the turn-on current of the unidirectional thyristor T1, the unidirectional thyristor T1 is turned on (at the same time there is a pressure difference between the anode and the cathode of the unidirectional thyristor T1), and The gate of the bus thyristor T outputs a trigger current, and the bus thyristor T is triggered to conduct under the combined action of the voltage difference between the anode and the cathode of the bus thyristor T and the trigger current from the unidirectional thyristor T1.

The above-mentioned high-voltage switch unit 31 uses a small SMD device (that is, one-way thyristor T1) as a high-voltage switch, which can not only withstand the high voltage applied to the DC bus at the moment of power-on of the whole machine, but also the normal working process after power-on It can also output to the gate of the bus thyristor T1 a trigger current to turn it on. Moreover, because the voltage drop between the anode and the cathode after the bus thyristor T is turned on becomes very small (about 1-2V), at this time the current flowing through the current limiting resistor R1 and the unidirectional thyristor T1 It will be reduced to a very small value. Even if the unidirectional SCR T1 is turned off at this time, as long as the bus SCR T has an anode current, it will continue to be turned on. Preferably, when the power supply of the power electronic device is a three-phase alternating current with a voltage level of 380V-480V, the withstand voltage level of the one-way thyristor is greater than 1200V.

In another embodiment of the present invention, the aforementioned isolation unit 32 may adopt an optocoupler isolation circuit, which includes an isolated optocoupler primary loop and an isolated optocoupler secondary loop, and the output terminal of the control unit is connected to the isolation The primary side loop of the optocoupler, and the secondary side loop of the isolated optocoupler are connected to the control end of the high-voltage switch unit 31. When the thyristor control signal output by the output terminal of the control unit is at a preset level, the isolation optocoupler primary loop is turned on, and the isolation optocoupler secondary loop is turned on, thereby generating a signal that turns on the high-voltage switch unit 31 .

The above-mentioned isolated optocoupler primary circuit belongs to the low-voltage control part, and the isolated optocoupler secondary circuit belongs to the high-voltage control part, so that the low-voltage control signal (that is, the thyristor control signal) output by the control unit can be converted into a high-voltage control signal, which realizes the control The complete isolation between the output terminal of the unit and the control terminal of the high-voltage switch unit 31 prevents damage to the components of the low-voltage part caused by the high-voltage current signal. That is to say, the isolation unit 32 realizes the insulation between the control unit of the power electronic equipment and the main circuit of the power electronic equipment by isolating the primary circuit of the optocoupler and the secondary circuit of the isolating optocoupler, without using high-voltage isolation devices, which can greatly reduce the isolation. The cost of the device.

In another embodiment of the present invention, the aforementioned isolated optocoupler secondary circuit includes a photosensitive device (included in the optocoupler U1), a first voltage divider resistor R1, and a second voltage divider resistor R2, and the input end of the photosensitive device constitutes an isolated light The power supply terminal of the coupling secondary circuit is connected to the first external power supply SCR_B (for example, +15V DC power supply), so as to provide a turn-on voltage for the isolated optocoupler secondary circuit through the first external power supply SCR_B. The output terminal of the photosensitive device is connected to the reference ground GND_SCR via the first voltage dividing resistor R3 and the second voltage dividing resistor R2. The connection point of the first voltage dividing resistor R3 and the second voltage dividing resistor R2 constitutes the output terminal of the isolation unit 32 and is connected To the control end of the high voltage switch unit 31. Therefore, when the secondary side of the isolation optocoupler is turned on, the control terminal of the high-voltage switch unit 31 (that is, the gate of the one-way thyristor T1) forms a trigger current, so that the high-voltage switch unit 31 is turned on.

In another embodiment of the present invention, the isolated optocoupler primary circuit includes a light emitting device (included in the optocoupler U1), a third voltage divider resistor R4, and a fourth voltage divider resistor R5. The input terminal of the light emitting device and the third One end of the voltage divider resistor R3 is commonly connected to form the power supply end of the isolated optocoupler primary circuit, and is connected to the second external power supply SCR_C (for example, +5V DC power supply), so that the second external power supply SCR_C is the isolated optocoupler original The side loop provides the turn-on voltage. The output terminal of the light-emitting device and the other end of the third voltage dividing resistor R4 are commonly connected to one end of the fourth voltage dividing resistor R5. The other end of the fourth voltage dividing resistor R5 constitutes the input terminal SCR_Control of the isolation unit 32 and is connected to To the output terminal of the control unit of the power electronic device. When the control unit outputs a low-level signal, the isolation optocoupler primary loop is turned on, and the isolation optocoupler secondary loop is turned on, so that the gate of the one-way thyristor T1 of the high-voltage switch unit 31 always keeps the trigger current Under the combined action of the anode and cathode pressure difference of the unidirectional thyristor T1, the unidirectional thyristor T1 is turned on.

The embodiment of the present invention also provides a power electronic device. The power electronic device can be a frequency converter, a drive, a UPS, a converter, etc., as shown in FIG. 4, the power device includes a DC bus connected in series for The buffer circuit that buffers the current at the moment of power-on of the whole machine and the above-mentioned drive circuit, the above-mentioned buffer circuit is composed of a buffer switch and a buffer resistor in parallel, and the buffer switch includes a bus thyristor T connected in parallel with the buffer resistor, and The output terminal of the high-voltage switch unit of the driving circuit is connected with the gate of the bus SCR T, and realizes the drive control of the bus SCR.

The DC bus includes a positive DC bus connected to the positive voltage output terminal of the rectifier unit and a negative DC bus connected to the negative voltage output terminal of the rectifier unit.

Specifically, the above-mentioned buffer circuit can be connected in series on the negative DC bus, and the cathode of the bus thyristor T is connected to the negative voltage output terminal of the rectifier unit, and the first power supply terminal of the driving circuit is connected to the anode of the above-mentioned bus thyristor T .

Alternatively, the buffer circuit may be connected in series on the positive DC bus, and the anode of the bus thyristor T is connected to the positive voltage output terminal of the rectifier unit, and the first power supply terminal of the driving circuit is connected to the anode of the bus thyristor.

Industrial applicability

The above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or changes within the technical scope disclosed by the present invention. All replacements shall be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

A drive circuit is applied to power electronic equipment. The power electronic equipment includes a buffer circuit connected in series on a DC bus and used to buffer the current at the moment of power-on of the whole machine. The buffer circuit is composed of a buffer switch and a buffer resistor. Composed in parallel, the buffer switch includes a bus thyristor connected in parallel with the buffer resistor, and the drive circuit is used to drive the bus thyristor, characterized in that the drive circuit includes an isolation unit and a high-voltage switch unit, in:

The input end of the isolation unit is connected to the output end of the control unit of the power electronic device, the output end of the isolation unit is connected to the control end of the high voltage switch unit, and the input end of the high voltage switch unit is connected to the bus controllable The anode of silicon, the output terminal of the high-voltage switch unit and the gate stage of the bus thyristor are connected to the reference ground;

At the moment when the power electronic device is powered on, the high-voltage switch unit remains in the off state. At this time, the bus thyristor is in the off state, and the peak value of the input voltage at the moment of power-on is simultaneously applied to the input terminal of the high-voltage switch unit And the output terminal, the power electronic device charges the bus capacitor through the buffer resistor;

When the bus voltage of the power electronic device rises to a preset value, the isolation unit controls the high-voltage switch unit to conduct according to the thyristor control signal input by the control unit, so that the high-voltage switch unit is The gate of the bus thyristor outputs a trigger current to control the bus thyristor to conduct, so that the power electronic device completes power-on buffering.
The driving circuit according to claim 1, wherein the high-voltage switch unit includes a current-limiting resistor and a unidirectional thyristor, and the anode of the unidirectional thyristor forms the The input terminal of the high-voltage switch unit is connected to the anode of the bus thyristor; the cathode of the one-way thyristor constitutes the output terminal of the high-voltage switch unit and is shared with the gate of the bus thyristor After being connected, it is connected to the reference ground; the gate stage of the one-way thyristor constitutes the control terminal of the high-voltage switch unit and is connected to the output terminal of the isolation unit.
The driving circuit of claim 1, wherein when the power supply of the power electronic device is a three-phase alternating current with a voltage level of 380V-480V, the withstand voltage level of the one-way thyristor is greater than 1200V.
The driving circuit of claim 1, wherein the isolation unit adopts an optocoupler isolation circuit, the optocoupler isolation circuit includes an isolated optocoupler primary loop and an isolated optocoupler secondary loop, and the control unit The output terminal of is connected to the isolation optocoupler primary loop, and the isolation optocoupler secondary loop is connected to the control terminal of the high-voltage switch unit.
The driving circuit according to claim 4, wherein the isolated optocoupler secondary side loop comprises a photosensitive device, a first voltage dividing resistor, and a second voltage dividing resistor, and the input end of the photosensitive device constitutes the isolated light The power supply terminal of the secondary side loop is connected to the first external power supply, the output terminal of the photosensitive device is connected to the reference ground via the first voltage dividing resistor and the second voltage dividing resistor, the first voltage dividing resistor The connection point with the second sub-resistor constitutes the output terminal of the isolation unit connected to the control terminal of the high-voltage switch unit.
The driving circuit according to claim 5, wherein the isolated optocoupler primary loop comprises a light emitting device, a third voltage dividing resistor, and a fourth voltage dividing resistor, and the input terminal of the light emitting device is connected to the third voltage dividing resistor. After one end of the voltage divider resistor is connected in common, the power supply end constituting the primary circuit of the isolation optocoupler is connected to the second external power supply, and the output end of the light-emitting device is connected to the other end of the third voltage divider resistor in common connection To one end of the four-voltage divider resistor, the other end of the fourth voltage divider constitutes the input end of the isolation unit and is connected to the output end of the control unit of the power electronic device.
A power electronic device includes a buffer circuit connected in series on a DC bus to buffer the current at the moment of power-on of the whole machine. The buffer circuit is composed of a buffer switch and a buffer resistor in parallel. The bus thyristor with parallel buffer resistors is characterized in that, the power electronic device further comprises the driving circuit according to any one of claims 1-6, and the bus thyristor is driven by the driving circuit .
The power electronic equipment according to claim 7, wherein the DC bus includes a positive DC bus and a negative DC bus;

The buffer circuit is connected in series on the negative DC bus; or, the buffer circuit is connected in series on the positive DC bus.