Inverter circuit for pre-charging and transmission device

Abstract

The utility model relates to an inverter circuit for pre-charging and transmission equipment, the inverter circuit comprises a rectification part, an inverter part and a direct current energy storage part connected between the rectification part and the inverter part, and the input end of the inverter part is connected to a power supply to receive a first current from the power supply; the output end of the inversion part is connected to the input end of the direct-current energy storage part and charges the direct-current energy storage part; the output end of the direct-current energy storage part is connected to the input end of the rectification part, and the output end of the rectification part is connected to a secondary winding of the transformer; the rectification part comprises at least one insulated gate bipolar transistor module, and in each insulated gate bipolar transistor module, current from the direct current energy storage part flows to the secondary winding through an insulated gate bipolar transistor chip. According to the invention, at least the technical effects of cost reduction, size reduction and complex operation are realized while pre-charging is realized.

Description

Technical Field

[0001] The present disclosure relates to the field of transmission equipment, and in particular to a circuit for precharging high-voltage transmission equipment. Background Art

[0002] High-voltage transmission equipment, or more specifically, high-voltage frequency converter, is a speed control device that changes the output frequency and output voltage to control the speed of AC high-voltage motors, and is an electric energy control device that uses the on-off function of power semiconductor devices to convert industrial frequency power supply into another frequency. High-voltage frequency converters are widely used in various fans, water pumps, compressors, rolling mills, etc. in large-scale mining production plants, petrochemicals, municipal water supply, metallurgy, steel, electric power and other industries.

[0003] At present, before the high-voltage inverter is connected to high-voltage power and starts working, it is necessary to pre-charge the high-voltage inverter to a specific voltage value to prevent excessive impact current from damaging components and reducing their life when connected to high-voltage power, and to prevent the upper-level protection device from tripping.

[0004] However, there are two main types of pre-charging circuits at present: high-voltage current limiting and low-voltage charging. The high-voltage current limiting requires a small isolation transformer to be hung on any winding, which adds extra components, resulting in high cost and large size. The low-voltage charging requires adding a duplicate winding of the transformer as a separate winding for pre-charging, which also adds extra components, resulting in high cost, large size and complex operation.

[0005] In view of this, the present application provides an inverter circuit and a high-voltage transmission device for pre-charging. The inverter circuit for pre-charging does not require the addition of additional windings or additional transformers to achieve the effects of reducing costs, reducing volume, and simplifying operations while pre-charging. Utility Model Content

[0006] The embodiments of the present disclosure provide an inverter circuit and a transmission device for pre-charging, so as to at least solve the problems of high cost, large size and complex operation of the circuit for pre-charging in the prior art.

[0007] According to one aspect of the present application, there is provided an inverter circuit for pre-charging, which is located in a transmission device and charges the transmission device before the transmission device is powered on to transmit power, characterized in that the inverter circuit includes a rectifier part, an inverter part, and a DC energy storage part connected between the rectifier part and the inverter part, the rectifier part, the inverter part and the DC energy storage part respectively include an input end and an output end, and the input end of the inverter part is connected to a power supply to receive a first current from the power supply, the output end of the inverter part is connected to the input end of the DC energy storage part and charges the DC energy storage part; the output end of the DC energy storage part is connected to the input end of the rectifier part, and the output end of the rectifier part is connected to the secondary winding of the transformer; wherein the rectifier part includes a plurality of parallel branches, each branch includes at least one insulated gate bipolar transistor module, each of the insulated gate bipolar transistor modules includes an insulated gate bipolar transistor chip and a freewheeling diode chip, and in each of the insulated gate bipolar transistor modules, the current from the DC energy storage part flows to the secondary winding via the insulated gate bipolar transistor chip.

[0008] In this way, by utilizing the inverter circuit inside the high-voltage inverter and by making the rectifier unit of the inverter circuit include multiple reverse-connected insulated gate bipolar transistor modules (wherein the current flows from the DC energy storage part to the secondary winding via the insulated gate bipolar transistor chip), the present application can reduce costs, reduce volume, and simplify operations during pre-charging without the need for additional components. In addition, after the pre-charging is completed, the reverse-connected insulated gate bipolar transistor module does not affect the original function of the inverter circuit in the high-voltage inverter, that is, during pre-charging, it inverts from right to left; during normal operation, it inverts from left to right.

[0009] According to an exemplary embodiment of the present application, when the DC energy storage part is charged so that the voltage reaches a set value, the insulated gate bipolar transistor chip is turned on and outputs a second current to the secondary winding.

[0010] In this way, when the inverter circuit is charged to meet the requirements, the secondary winding is energized by controlling the conduction of the insulated gate double-click transistor. According to the principle of electromagnetic induction, the charged secondary winding causes the primary winding of the transformer to also induce current.

[0011] According to an exemplary embodiment of the present application, it also includes a contactor connected between the input end of the inverter part and the power supply, the contactor includes two normally open contacts connected between the input end of the inverter part and the power supply, a connecting rod connected to the two normally open contacts at the same time, and a control coil connected to the connecting rod and an external controller.

[0012] In this way, the two normally open contacts of the contactor are arranged at a certain distance from the output end of the inverter unit outputting three-phase AC to meet the distance requirements of high-voltage reinforced insulation, thereby achieving high and low voltage isolation, safety and reliability.

[0013] According to an exemplary embodiment of the present application, after the insulated gate bipolar transistor chip is turned on and outputs the second current to the secondary winding, the control coil is de-energized and the connecting rod disconnects the two normally open contacts.

[0014] In this way, after the secondary winding receives the second current, the primary winding will induce current. At this time, it is determined that the pre-charging is completed, and the control coil end and the connecting rod of the contactor disconnect the contacts and exit the control.

[0015] According to an exemplary embodiment of the present application, a circuit breaker connected between the two normally open contacts and the power supply is also included.

[0016] According to an exemplary embodiment of the present application, a current limiting resistor connected between the two normally open contacts and the power supply is also included.

[0017] In this way, the present application adds further protection measures, that is, both the circuit breaker and the current limiting resistor are used to protect the circuit to terminate the pre-charging process when an abnormality occurs in the circuit.

[0018] According to an exemplary embodiment of the present application, the transformer is a phase-shifting transformer and includes a plurality of secondary windings, and one secondary winding of the plurality of secondary windings is connected to one of the inverter circuits.

[0019] In this way, when there are multiple secondary windings, when one of the multiple secondary windings is connected to an inverter circuit, one secondary winding is energized and causes the primary winding to induce current accordingly, and the correspondingly energized primary winding causes the remaining secondary windings to induce current, and the remaining energized secondary windings will pre-charge the inverter circuits to which they are connected.

[0020] Therefore, the novel pre-charging circuit of the present application can be implemented on only one inverter unit, and implementing it on one inverter unit also achieves the purpose of reducing the charging current of each pre-charging circuit.

[0021] In addition, the novel pre-charging circuit can also be implemented on multiple inverter units, and this structure can achieve the purpose of increasing the charging speed of each pre-charging circuit.

[0022] According to an exemplary embodiment of the present application, the power supply is a 220V AC power supply, the first current is a single-phase AC current, and the second current is a three-phase AC current.

[0023] In this way, the present application does not need to use 380Vac used in the prior art, but can use a lower 220Vac to achieve the pre-charging function, and the present application can also rectify and invert the single-phase AC current into a three-phase AC current.

[0024] According to an exemplary embodiment of the present application, there are three parallel branches, and each branch includes two insulated gate bipolar transistor modules.

[0025] In this way, since the rectifying part of the present application outputs three-phase AC current, there are three parallel branches, each branch including two insulated gate bipolar transistor modules.

[0026] According to an exemplary embodiment of the present application, the inverter circuit further includes an isolation transformer connected between an input terminal of the inverter part and a power source.

[0027] In this way, since the isolation transformer can isolate the high voltage and low voltage on both sides thereof, the safety of the system and personnel on the low voltage side can be guaranteed during and after the pre-charging process, and the adjustment of the primary and secondary voltages can also be achieved.

[0028] According to another aspect of the present application, a transmission device includes a transformer, an inverter circuit connected to the transformer, and a controller connected to the transformer and the inverter circuit, wherein the controller controls the transformer and the inverter circuit through an optical fiber.

[0029] In this way, the present application provides an improved transmission device.

[0030] In an embodiment of the present application, a technical solution is provided in which an inverter circuit includes a rectifier part connected to the secondary winding of a transformer, an inverter part connected to a power supply, and a DC energy storage part connected between the rectifier part and the inverter part, and the rectifier part includes multiple parallel branches, each branch includes at least one insulated gate bipolar transistor module, and in each insulated gate bipolar transistor module, the current from the DC energy storage part flows to the secondary winding via the insulated gate bipolar transistor chip, so as to at least solve the technical problems of high cost, large size and complex operation of the pre-charging circuit in the prior art, and achieve the technical effect of reducing cost, reducing size and simplifying operation while pre-charging. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0032] Figure 1is a schematic diagram showing an inverter circuit for pre-charging according to an embodiment of the present application;

[0033] Figure 2 The embodiment of the present application is shown in FIG. Figure 1 The schematic diagram of the transmission device of the inverter circuit is shown.

[0034] Reference Numbers

[0035] 1: Inverter circuit;

[0036] 2: Transformer;

[0037] 3: Controller;

[0038] 11: Rectification part;

[0039] 12: Inverter part;

[0040] 13: DC energy storage part;

[0041] 14: Power supply;

[0042] 15: Secondary winding;

[0043] 161: Two normally open contacts;

[0044] 162: Connecting rod;

[0045] 163: control coil;

[0046] 17: External controller;

[0047] 18: Circuit breaker;

[0048] 19: Current limiting resistor;

[0049] 111: Insulated gate bipolar transistor chip;

[0050] 112: freewheeling diode chip;

[0051] T: Isolation transformer. DETAILED DESCRIPTION

[0052] Hereinafter, embodiments of the present application will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement embodiments of the present application. However, the present application can be implemented in many different forms and should not be construed as being limited to the embodiments described herein. In the accompanying drawings, for the sake of clarity, parts that are irrelevant to the description of the present application will be omitted. Similar reference numerals refer to similar elements throughout the description. In addition, when providing a description with reference to the accompanying drawings, although the elements are represented by the same numerals, the reference numerals relating to the elements may be changed, and the reference numerals are described only for the convenience of description, and should not be understood as the concept, feature, function or effect of the element being limited by the reference numeral.

[0053] In the prior art, the circuit for precharging high-voltage transmission equipment or high-voltage frequency converter has technical problems of high cost, large size and complex operation.

[0054] In order to solve this technical problem, the present application proposes an improved inverter circuit for pre-charging and a transmission device including the inverter circuit.

[0055] Figure 1 is a schematic diagram showing an inverter circuit for pre-charging according to an embodiment of the present application;

[0056] like Figure 1 As shown, the inverter circuit 1 includes a rectifying part 11, an inverting part 12 and a DC energy storage part 13 connected between the rectifying part and the inverting part. The rectifying part 11, the inverting part 12 and the DC energy storage part 13 include an input end and an output end respectively.

[0057] In the prior art, when the high-voltage frequency converter is working normally, that is, when it is powered on to transmit electricity, the function of the rectifier part 11 is to rectify the high-voltage power. The DC energy storage part 13 converts the rectified current into a DC current, so that the pulsating DC voltage becomes stable or smooth for use by the inverter part; the DC energy storage part 13 can be regarded as an energy storage device, and the motor can obtain energy from the intermediate circuit through the inverter. The inverter part 12 converts the DC power output by the DC circuit into an AC power supply whose frequency and voltage can be arbitrarily adjusted for output. The output of the inverter circuit 1 is the output of the frequency converter, so the inverter circuit is one of the core circuits of the frequency converter and plays a very important role.

[0058] When precharging a high voltage inverter to prevent component damage, increase component life, and prevent malfunction, the inverter circuit 1 is improved for reverse charging without requiring additional components.

[0059] Specifically, before the high-voltage transmission device is powered on to transmit power, that is, during pre-charging, the input end of the inverter part 12 is connected to the power supply 14 to receive a single-phase AC current, specifically, the power supply 14 is 220Vac. The received AC current is inverted into a DC current via a plurality of insulated gate bipolar transistor modules connected in a positive direction inside the inverter part 12 (wherein the current from the power supply flows through the freewheeling diode part of the insulated gate bipolar transistor module).

[0060] The inverted DC current is stored in the DC energy storage part 13, whereby the DC energy storage part 13 is charged so that the voltage increases. When the voltage increases to a predetermined value, the DC energy storage part 13 outputs the DC current to the connected rectifying part 11.

[0061] The rectifier part 11 includes a plurality of insulated gate bipolar transistor modules connected in a three-phase bridge, wherein three branches are connected in parallel and each branch includes two insulated gate bipolar transistor modules, and each insulated gate bipolar transistor module includes an insulated gate bipolar transistor chip 111 and a freewheeling diode chip 112. The DC current from the DC energy storage part 13 turns on the insulated gate bipolar transistor module and flows through the insulated gate bipolar transistor chip 111, but does not flow through the freewheeling diode chip 112. Thus, the DC current is inverted into a three-phase AC current via the insulated gate bipolar transistor module of the rectifier part 11.

[0062] The rectifier part 11 using the insulated gate bipolar transistor module can be used when the high-voltage inverter normally converts power. Figure 1 As shown, power is converted from left to right and supplied to loads such as motors; in addition, it is also possible to pre-charge the high-voltage inverter, such as Figure 1 As shown, power is converted from right to left and the high voltage inverter is pre-charged.

[0063] The output terminal of the rectifying part 11 is connected to the secondary winding of the phase-shifting transformer and the three-phase AC current is input to the secondary winding.

[0064] The energized secondary winding induces current in the corresponding primary winding.

[0065] Thus, when the voltage of the DC energy storage part 13 reaches a predetermined value, or when the secondary winding receives current, or when the primary winding of the phase-shifting transformer induces current, the pre-charging of the inverter circuit is completed.

[0066] In addition, the phase-shifting transformer may include multiple secondary windings, and the inverter circuit 1 of the present application may be implemented on one secondary winding side or on multiple secondary winding sides at the same time.

[0067] When a secondary winding of multiple secondary windings is connected to an inverter circuit 1, the charged secondary winding causes the corresponding primary winding to induce current, and correspondingly, the charged primary winding causes the remaining secondary windings of the multiple secondary windings to also induce current, and then the induced current passes through the freewheeling diode chip 112 of the rectifying part 11, the DC energy storage part 13 and the inverter part 12 to pre-charge the inverter circuit 1.

[0068] When each of the secondary windings of the plurality of secondary windings is connected to an inverter circuit 1, each secondary winding receives a three-phase AC current and causes the primary winding to induce a current. In addition, each inverter circuit can be connected to a power supply 14, which speeds up the pre-charging speed of each inverter circuit. In addition, each inverter circuit can be connected to a power supply 14 in common, which reduces the pre-charging current of each inverter circuit.

[0069] When the phase-shifting transformer includes multiple secondary windings, the pre-charging of the inverter circuit is completed when the voltage of each DC energy storage part 13 reaches a predetermined value, or when each secondary winding receives current, or when current is induced in the primary winding of the phase-shifting transformer.

[0070] like Figure 1 As shown, the inverter circuit 1 also includes a high-voltage isolated electromagnetically attracted bypass contactor installed between the input end of the inverter part 12 and the power supply 14, and the contactor includes two normally open contacts 161 connected between the input end of the inverter part 12 and the power supply 14, a connecting rod 162 connected to the two normally open contacts at the same time, and a control coil 163 connected to the connecting rod and the external controller 17.

[0071] The distance between the two normally open contacts 161 and the input terminal of the inverter part 12 meets the distance requirement of high voltage reinforced insulation.

[0072] When the high-voltage inverter determines through self-test that there is no fault in the control system, the external controller 17 sends a control signal to the control coil 163, and the control coil 163 closes the two normally open contacts 161 through the connecting rod 162, so that the current of the power supply 14 reaches the secondary winding via the inverter part 12, the DC energy storage part 13 and the rectifier part 11.

[0073] When the pre-charging is completed, the external controller 17 controls the control coil 163 to open. After the control coil 163 opens, the quantity 162 disconnects the two normally open contacts 161, thereby exiting the control.

[0074] In this way, the external controller 17 controls the entire pre-charging process more flexibly via the contactor, and after the pre-charging is completed, the power supply is disconnected so that the pre-charged inverter circuit can be used for the subsequent normal operation of the high-voltage inverter.

[0075] In addition, the inverter circuit 1 further includes a circuit breaker 18 connected between the two normally open contacts and the power supply, and a current limiting resistor 19 connected between the two normally open contacts and the power supply.

[0076] The present application further strengthens the protection measures of the inverter circuit 1 through the circuit breaker 18 and the current limiting resistor 19 to terminate the pre-charging process when an abnormality occurs in the inverter circuit 1.

[0077] Furthermore, the inverter circuit 1 further includes an isolation transformer T installed between the inverter portion 12 and the power source 14 .

[0078] At present, the phase-shifting transformer of the high-frequency transformer includes a plurality of secondary windings, and each secondary winding is connected to an inverter circuit. Each inverter circuit is in a series structure. After each inverter circuit is precharged, the plurality of inverter circuits connected in series form a high voltage on the side of the inverter part 12 close to the power supply, which may cause safety hazards to the power supply 14 and the systems and personnel on the side of the power supply 14.

[0079] To this end, the isolation transformer T in the inverter circuit 1 can isolate the high voltage formed on the side of the inverter part 12 close to the power supply (that is, during the pre-charging process, this side is the input end, and during the normal working period after the pre-charging process is completed, this side is the output end) from the high and low voltage of the power supply 14, thereby ensuring the safety of the system and personnel on the power supply 14 side during and after the pre-charging process.

[0080] Figure 2 The embodiment of the present application is shown in FIG. Figure 1 The schematic diagram of the transmission device of the inverter circuit is shown.

[0081] like Figure 2 As shown, the transmission device includes an inverter circuit 1, a transformer 2 and a controller 3.

[0082] The controller 3 controls the operations of the inverter circuit 1 and the transformer 2 through the optical fiber.

[0083] Fiber optic control has the advantages of fast speed and reliability.

[0084] In the embodiments of the present application, a technical solution is provided to at least solve the technical problems in the prior art and achieve the technical effects.

[0085] In the above embodiments of the present application, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, please refer to the relevant description of other embodiments.

[0086] In the several embodiments provided in this application, it should be understood that the disclosed technical contents can be implemented in other ways.

[0087] The above is only a preferred implementation of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. An inverter circuit (1) for pre-charging, located in a transmission device and charging the transmission device before the transmission device is powered on to transmit power, characterized in that The inverter circuit comprises a rectifier part (11), an inverter part (12), and a DC energy storage part (13) connected between the rectifier part and the inverter part, wherein the rectifier part, the inverter part, and the DC energy storage part respectively comprise an input end and an output end, and The input end of the inverter part is connected to a power source (14) to receive a first current from the power source, the output end of the inverter part is connected to the input end of the DC energy storage part and charges the DC energy storage part; the output end of the DC energy storage part is connected to the input end of the rectifier part, and the output end of the rectifier part is connected to the secondary winding (15) of the transformer; The rectifying part comprises a plurality of parallel branches, each branch comprises at least one insulated gate bipolar transistor module, each of the insulated gate bipolar transistor modules comprises an insulated gate bipolar transistor chip (111) and a freewheeling diode chip (112), and in each of the insulated gate bipolar transistor modules, the current from the DC energy storage part flows to the secondary winding via the insulated gate bipolar transistor chip.

2. The inverter circuit according to claim 1, characterized in that: When the DC energy storage part is charged so that the voltage reaches a set value, the insulated gate bipolar transistor chip is turned on and outputs a second current to the secondary winding.

3. The inverter circuit according to claim 2, characterized in that: It also includes a contactor connected between the input end of the inverter part and the power supply, the contactor includes two normally open contacts (161) connected between the input end of the inverter part and the power supply, a connecting rod (162) connected to the two normally open contacts at the same time, and a control coil (163) connected to the connecting rod and an external controller (17).

4. The inverter circuit according to claim 3, characterized in that: After the insulated gate bipolar transistor chip is turned on and outputs the second current to the secondary winding, the control coil is powered off and the connecting rod disconnects the two normally open contacts.

5. The inverter circuit according to claim 4, characterized in that: Also included is a circuit breaker (18) connected between the two normally open contacts and the power source.

6. The inverter circuit according to claim 5, characterized in that: It also includes a current limiting resistor (19) connected between the two normally open contacts and the power supply.

7. The inverter circuit according to claim 1, characterized in that: The transformer is a phase-shifting transformer and includes a plurality of secondary windings, and one secondary winding of the plurality of secondary windings is connected to one of the inverter circuits.

8. The inverter circuit according to claim 2, characterized in that: The power supply is a 220V AC power supply, the first current is a single-phase AC current, and the second current is a three-phase AC current.

9. The inverter circuit according to claim 1, characterized in that: There are three parallel branches, and each branch includes two insulated gate bipolar transistor modules.

10. The inverter circuit according to claim 1, characterized in that: It also includes an isolation transformer (T) connected between the input end of the inversion part and the power supply (14).

11. A transmission device, characterized in that: The transmission device comprises a transformer (2), an inverter circuit (1) according to any one of claims 1 to 10 connected to the transformer, and a controller (3) connected to the transformer and the inverter circuit, wherein the controller controls the transformer and the inverter circuit via an optical fiber.

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