Power unit and frequency converter

Abstract

The utility model relates to the technical field of frequency converters, in particular to a power unit and a frequency converter, comprising a control board, a power driving board and a resistance-capacitance board which are wrapped in a power unit frame and are connected with each other, the power driving board and the resistance-capacitance board are arranged above the control board; a direct-current filter circuit is arranged on the resistance-capacitance plate and is connected with the rectifier module and the driving module; the positive and negative buses of the DC filter circuit coincide in the overlook direction. In order to solve the problem that the switching loss of a power device is increased due to the fact that the stray inductance of a power unit is improved after device integration in the prior art, in the scheme, a direct-current filter circuit which is usually arranged on a power driving board is split, and an independent resistance-capacitance board is arranged for placing the direct-current filter circuit; therefore, the distance between the direct-current filter circuit and the power device is increased, meanwhile, the positive bus and the negative bus are stacked on the resistance-capacitance plate, stray inductance is eliminated, and switching loss caused by the stray inductance is further reduced.

Description

Technical Field

[0001] This utility model relates to the field of frequency converter technology, specifically to a power unit and a frequency converter. Background Technology

[0002] A high-voltage frequency converter is a power electronic device used to control and regulate high-voltage AC motors, enabling precise control of the motor's speed, start / stop, and operating status. It typically operates at high voltage levels and is suitable for high-power motor drive systems. The core component of a high-voltage frequency converter is the power unit, which mainly includes a rectifier circuit and a motor drive circuit. It rectifies the input voltage and then outputs specific motor drive signals to drive each phase of the motor. To control the power devices in the motor drive circuit, a control board is usually required. The control board needs external input signals to determine the control mode and necessary parameters, such as acceleration, deceleration, and motor status, and then generates control signals for the power devices through a series of calculations.

[0003] In the prior art, in order to achieve a more compact device layout, the above-mentioned circuits are usually integrated into a frame structure.

[0004] For example, Chinese patent application CN202411388778.4 discloses an integrated dual H-bridge power unit module, which includes two three-phase rectifier bridges + H-bridge modules mounted on a heat sink to form a dual H-bridge circuit, realizing dual-module series output and improving power density; the module adapter board realizes integrated and modular design, improving production efficiency; the main circuit current terminals are welded around the control terminals to reduce the interference of the main circuit to the drive control circuit; the bypass power relay meets the bypass output in case of fault; the filter energy storage capacitor is divided into two groups, which provide energy storage and filtering for the corresponding H-bridge inverters; the two independent unit inputs are connected to fast fuses through input cables, and cable sheaths are installed at the through holes of the main housing, and the internal cable support components guide and limit the cable routing; under the premise of meeting structural strength and electrical performance, it has the characteristics of high power density, high integration, high installation efficiency, and convenient maintenance, solving the problems of large number of power unit modules, low power density, large size, and complex installation.

[0005] However, in actual implementation, the inventors found that as the device integration density of the integrated power unit module increases and the distance between the devices gets closer, the stray inductance will increase, which in turn will further increase the switching loss of the power devices. Utility Model Content

[0006] To address the aforementioned problems in the existing technology, a power unit is now provided;

[0007] On the other hand, frequency converters that utilize this power unit are also provided.

[0008] The specific technical solution is as follows:

[0009] A power unit includes a control board, a power drive board, and a resistor-capacitor board that are enclosed in a power unit frame and interconnected with each other.

[0010] The power drive board and the resistor-capacitor board are disposed above the control board, and the power drive board is provided with a power drive circuit.

[0011] The control board is equipped with a control circuit corresponding to the power drive circuit.

[0012] The power drive circuit includes a rectifier module and a drive module;

[0013] A DC filter circuit is provided on the resistor-capacitor board. The input terminal of the DC filter circuit is connected to the rectifier module, and the output terminal of the DC filter circuit is connected to the drive module.

[0014] The positive and negative buses of the DC filter circuit coincide when viewed from above.

[0015] On the other hand, the DC filter circuit includes multiple filter capacitors;

[0016] The filter capacitor is disposed on the upper surface of the resistor-capacitor plate and passes through a pre-set hole on the power unit frame to reach the outside;

[0017] The leads of the filter capacitor are in the form of bent wire arrays;

[0018] The conductor bar is provided with screw holes, and the conductor bar is fixed to the resistor-capacitor plate by bolts.

[0019] On the other hand, external components are provided on the power unit frame;

[0020] The external component extends upward along the preset hole;

[0021] The external connector is attached to the outside of the filter capacitor via a clamp.

[0022] On the other hand, the power drive board includes a first power drive board and a second power drive board;

[0023] The first power drive board and the second power drive board are arranged side by side along the long axis of the power unit frame;

[0024] One of the power drive circuits is respectively provided on the first power drive board and the second power drive board;

[0025] The resistive capacitor plate includes a first resistive capacitor plate and a second resistive capacitor plate;

[0026] The first resistor-capacitor plate and the second resistor-capacitor plate are respectively disposed on the outer side of the first power drive plate and the second power drive plate;

[0027] One DC filter circuit is respectively provided on the first resistor-capacitor board and the second resistor-capacitor board;

[0028] The adjacent DC filter circuit and the power drive circuit are connected by a bridging copper busbar;

[0029] The first power drive board and the second power drive board are respectively connected to the control board below via pins.

[0030] On the other hand, the power drive board is equipped with an integrally packaged PIM-IGBT device;

[0031] The power drive circuit is integrated into the PIM-IGBT device;

[0032] A heat sink is soldered on top of the PIM-IGBT device;

[0033] The heat sink passes through the power unit frame and is exposed to the outside.

[0034] On the other hand, the number of PIM-IGBT devices is two sets;

[0035] The PIM-IGBT devices are arranged in parallel;

[0036] The two heat sinks are securely connected to the power unit frame above by heat sink connectors.

[0037] On the other hand, the power unit frame is provided with multiple input and output terminals on its side;

[0038] The input / output terminals pass through the power unit frame and are connected to the power drive board;

[0039] The input and output terminals are fixed to the power unit frame by bolts.

[0040] On the other hand, the power unit frame has a fuse fixed on the side near the input and output terminals;

[0041] The fuse is arranged along the height of the power unit frame, and passes through the power unit frame via a copper busbar and is connected to the power drive board.

[0042] On the other hand, the power unit frame has an opening on the side near the filter capacitor.

[0043] A frequency converter includes the power unit described above.

[0044] The above technical solution has the following advantages or beneficial effects:

[0045] To address the issue of increased stray inductance in power units after device integration in existing technologies, which leads to increased switching losses in power devices, this solution separates the DC filter circuit, which is typically located on the power drive board, and sets up an independent resistor-capacitor board to house the DC filter circuit. This increases the distance between the DC filter circuit and the power devices. At the same time, the positive and negative buses are stacked on the resistor-capacitor board, thereby eliminating stray inductance and further reducing the switching losses caused by stray inductance. Attached Figure Description

[0046] Embodiments of the present invention will be described more fully with reference to the accompanying drawings. However, the accompanying drawings are for illustration and explanation only and do not constitute a limitation on the scope of the present invention.

[0047] Figure 1 This is an overall schematic diagram of an embodiment of the present utility model;

[0048] Figure 2 This is a schematic diagram of the circuit principle in an embodiment of the present invention;

[0049] Figure 3 This is a schematic diagram of the driver board in an embodiment of the present invention;

[0050] Figure 4 This is a schematic diagram of the input / output terminals in an embodiment of the present invention;

[0051] Figure 5 This is a schematic diagram of the side plate in an embodiment of the present invention. Detailed Implementation

[0052] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0053] It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0054] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the present invention.

[0055] This utility model includes:

[0056] A power unit, such as Figure 1-5As shown, it includes a control board 2, a power drive board 3, and a resistor-capacitor board 4, which are enclosed in the power unit frame 1 and interconnected.

[0057] The power drive board 3 and the resistor-capacitor board 4 are positioned above the control board 2, and the power drive board 3 is equipped with a power drive circuit 3A.

[0058] The control board 2 is equipped with a control circuit 2A corresponding to the power drive circuit 3A;

[0059] The power drive circuit 3A includes a rectifier module 3A1 and a drive module 3A2;

[0060] A DC filter circuit 4A is provided on the resistor-capacitor board 4. The input terminal of the DC filter circuit 4A is connected to the rectifier module 3A1, and the output terminal of the DC filter circuit 4A is connected to the drive module 3A2.

[0061] The positive and negative buses of the DC filter circuit 4A coincide when viewed from above.

[0062] Specifically, in response to the problem that stray inductance increases after the power unit is integrated in the prior art, thereby increasing the switching loss of the power device, this embodiment first analyzes the source of stray inductance in the power unit and determines that some stray inductance may be introduced in the DC filter circuit 4A, which will cause switching loss of the power device.

[0063] To solve this problem, in this embodiment, the DC filter circuit 4A is separated and an independent resistor-capacitor board 4 is set up to set the circuit structure on the DC filter circuit 4A, including the DC filter circuit and filter capacitors, etc.

[0064] The power drive circuit 3A is set on another power drive board 3. The spacing between the two is increased by splitting the DC filter circuit 4A, which reduces the influence of stray inductance.

[0065] Meanwhile, during wiring, the positive and negative buses of the DC filter circuit 4A are respectively laid on the two layers of the resistor-capacitor board 4, and the positive and negative buses are controlled to overlap in the top view direction, thereby eliminating stray inductance and further reducing the impact of stray inductance in the compact power unit layout.

[0066] Specifically, the circuit structure of this power unit mainly includes the following components: rectifier module 3A1 and drive module 3A2, control circuit 2A and DC filter circuit 4A.

[0067] The rectifier module 3A1, depending on the input type (e.g., single-phase AC or three-phase AC), is a rectifier circuit similar to a rectifier bridge or a six-pulse diode rectifier circuit. Its main function is to convert externally input AC power into DC power and input it to the DC bus within the power unit. Depending on the requirements, it may also include filter capacitors, Zener diodes, transformers, and other devices.

[0068] On the DC bus, the DC filter circuit 4A is first input. The DC filter circuit 4A mainly includes some resistors and filter capacitors, which are used to form various series and parallel RC filter circuits to eliminate the ripple on the DC bus.

[0069] Subsequently, the input is processed into the drive module 3A2. The drive module 3A2 is a motor drive circuit, typically configured as a full-bridge drive circuit for three-phase motors. This circuit has power switches for the upper and lower bridge arms of each phase. The power switches are commonly MOSFETs or IGBTs. The three-phase motor is controlled by turning on each power switch in a specific sequence.

[0070] To control the power devices in the drive module 3A2, a control circuit 2A is also provided. It is usually connected to other external devices through signal lines, such as optical fibers, and obtains the corresponding control requirements, such as motor acceleration, deceleration, rotation to a specific position, and corresponding control parameters, such as current value and actual motor speed. Then, it combines the relevant motor control algorithm to provide relevant control signals to the drive module 3A2 to control the power devices.

[0071] To achieve a high degree of device integration for the aforementioned circuit structure, this embodiment first constructs a rectangular, box-shaped power unit frame 1. This power unit frame 1 is roughly injection-molded, with metal embedded at some points. A control board 2 is placed at the bottom of the power unit frame 1. The control board 2 forms the aforementioned control circuit 2A through discrete components, integrated circuits, and printed circuits.

[0072] Then, a drive board 3 is placed above the control board 2. The drive board 3 houses the rectifier module 3A1 and drive module 3A2 of the power drive circuit 3A. The control board 2 and drive board 3 transmit control signals and low-voltage power supply signals through vertical connectors. On the side of the drive board 3, an independent resistor-capacitor board 4 is placed to house the circuit structure of the DC filter circuit 4A, including the DC filter circuit and filter capacitors. The two are connected by copper busbars. The drive board 3 is connected to external circuits, including the front-end AC power supply circuit and the rear-end motor, through through-wall terminals. By splitting the DC filter circuit 4A, the spacing between the two is increased, reducing the influence of stray inductance.

[0073] The main parts of the control board 2, drive board 3, and resistor-capacitor board 4 are enclosed in the power unit frame 1, while some structures, such as chip heat sinks and large capacitors, are exposed through perforations.

[0074] Considering actual product requirements, the power unit can also be equipped with two drive circuits to achieve dual output or dual cascaded output, thereby meeting different drive requirements.

[0075] Taking dual-channel superimposed output as an example, this scenario achieves greater driving power by superimposing the output signals of corresponding phases of two power drive circuits 3A. In this embodiment, the number of drive boards 3 can be set to two, and the number of resistor-capacitor boards 4 can also be set to two, arranged sequentially along the long axis of the power unit frame 1. The drive boards 3 and resistor-capacitor boards 4 are set one-to-one to form a complete power drive circuit and filter circuit for output. The two drive boards 3 can share a control board 2.

[0076] A typical arrangement is shown in the diagram. Two drive boards 3 are arranged side by side in the middle of the power unit frame 1, and resistor-capacitor boards 4 are respectively arranged at both ends of the power unit frame 1, connecting to the adjacent drive boards 3 respectively. The control board 1 is located on the lower layer.

[0077] In one embodiment, the DC filter circuit 4A includes a plurality of filter capacitors 40;

[0078] The filter capacitor 40 is placed on the upper surface of the resistor-capacitor plate 4 and passes through the preset hole on the power unit frame 1 to reach the outside;

[0079] The lead of the filter capacitor 40 is a bent wire bar 42;

[0080] The wire bar 42 is provided with screw holes and is fixed to the resistor plate 4 by bolts.

[0081] Specifically, to achieve a more robust installation, in this embodiment, the filter capacitor 40 is replaced with a model that has a wider conductor bar 42 at the bottom. The lead of this model of filter capacitor 42 is a sheet-like conductor bar with a certain thickness. When bent, it can serve as a support to support the filter capacitor 40 above. At this time, the conductor bar 42 is fixed to the resistor-capacitor plate by bolts to form an electrical connection, thereby achieving better installation strength.

[0082] Meanwhile, considering the overall compactness of the device and the heat dissipation effect, the filter capacitor 40 passes through the preset hole on the power unit frame 1 to reach the outside.

[0083] In one embodiment, an external component 11 is provided on the power unit frame 1;

[0084] External component 11 extends upward along the pre-set hole;

[0085] The external component 11 is connected to the outside of the filter capacitor 40 via the clamp 12.

[0086] Specifically, in order to achieve a more secure fixation of the filter capacitor, an external component 11 is also provided in this embodiment. The external component 11 is fixed on the power unit frame 1 and extends upward. Then, it is connected to the outside of the filter capacitor 40 by a clamp 12 to effectively fix the protruding part of the filter capacitor 40.

[0087] In one embodiment, the power drive board 3 includes a first power drive board 31 and a second power drive board 32.

[0088] The first power drive board 31 and the second power drive board 32 are arranged side by side along the long axis of the power unit frame 1.

[0089] A power drive circuit is respectively provided on the first power drive board 31 and the second power drive board 32;

[0090] The resistive capacitor plate 4 includes a first resistive capacitor plate 41 and a second resistive capacitor plate 42;

[0091] The first resistor-capacitor plate 41 and the second resistor-capacitor plate 42 are respectively disposed on the outer sides of the first power drive plate 41 and the second power drive plate 43.

[0092] A DC filter circuit 4A is respectively provided on the first resistor-capacitor plate 41 and the second resistor-capacitor plate 42;

[0093] The adjacent DC filter circuit 4A and power drive circuit 3A are connected by a bridging copper busbar 33;

[0094] The first power drive board 31 and the second power drive board 32 are respectively connected to the control board 2 below via pins.

[0095] Specifically, to achieve dual outputs, in this embodiment, the power driver board 3 is configured as a first power driver board 31 and a second power driver board 32, and the resistor-capacitor board is configured as a first resistor-capacitor board 41 and a second resistor-capacitor board 42, arranged sequentially along the long axis of the power unit frame 1. The first resistor-capacitor board 41 and the second resistor-capacitor board 42 are respectively located outside the first power driver board 41 and the second power driver board 43, and are connected to adjacent circuits through a bridging copper busbar 33. The first power driver board 31 and the second power driver board 32 are connected to the outside for input and output through specific terminals. During output, they can output separately, or the corresponding midpoints of the output phase lines can be connected to achieve superimposed output. The above design can reduce the product size.

[0096] In one embodiment, a fully packaged PIM-IGBT device (not shown in the figure) is disposed on the power driver board 3;

[0097] The power drive circuit 3A is integrated into the PIM-IGBT device;

[0098] A heat sink 34 is soldered on top of the PIM-IGBT device;

[0099] The heat sink 34 passes through the power unit frame and is exposed.

[0100] Specifically, in order to achieve better integration and reduce stray inductance, a PIM-IGBT device is provided in this embodiment. The device includes a set of three-phase uncontrolled rectifier circuits and a set of H-bridge inverter circuits, which are connected through the internal circuit of the chip, thereby reducing the trace length and stray inductance.

[0101] When there are two drive circuits, the number of PIM-IGBT devices is two sets;

[0102] PIM-IGBT devices are arranged in parallel;

[0103] The two heat sinks 34 are fastened to the power unit frame 1 above by heat sink connectors 35.

[0104] Specifically, in order to achieve a better fixing effect on the heat sink, in this embodiment, the two heat sinks 34 are fixed above by heat sink connectors 35. The heat sink connectors 45 are roughly a frame structure, which are fastened to the power unit frame 1 by bolts.

[0105] The heat sink 34 is connected to the PIM-IGBT device by a brazing process. It is usually equipped with a support at its bottom, which is bolted to the power drive board 3 by a specific clamp.

[0106] Radiator 34 is usually a finned radiator, formed by aluminum extrusion, but it can also be other equivalent radiators.

[0107] In one embodiment, the power unit frame 1 has a plurality of input / output terminals 13 on its side;

[0108] The input / output terminal 13 passes through the power unit frame 1 and is connected to the power drive board 3;

[0109] The input / output terminals 13 are fixed to the power unit frame 1 by bolts.

[0110] Specifically, in order to achieve better input and output performance, in this embodiment, multiple input and output terminals 13 are provided on the side of the power unit frame 1. The input and output terminals 13 are through-wall copper busbar terminals, with both ends passing through the side wall of the power unit frame 1 and fixed by bolts. The inner extension extends to a certain position and is connected and fixed to the corresponding position on the power drive board 3 by bolts to form an electrical connection. The outer extension also extends out a portion and is connected to the external circuit by copper busbar, plug, etc.

[0111] In some embodiments, one set of input / output terminals 13 is replaced with fiber optic plugs 13A and connected to a control board for communication via optical signals.

[0112] In one embodiment, a fuse 14 is fixed on the side of the power unit frame 1 near the input and output terminals;

[0113] The fuse 14 is arranged along the height direction of the power unit frame 1, and passes through the power unit frame 14 via a copper busbar and is connected to the power drive board 3.

[0114] Specifically, to facilitate observation of the fuse status, in this embodiment, the DC bus section on the power drive board 3 is led out through a copper busbar, passes through the power unit frame 1 to the outside, and then connected to the fuse 14. The fuse 14 is set along the height direction of the power unit frame 1, and its appearance will change when triggered, making it easy to observe.

[0115] In one embodiment, the power unit frame 1 has an opening 15 on the side near the filter capacitor 41.

[0116] Specifically, to achieve better cooling of the capacitor, in this embodiment, after placing the filter capacitor 41 near the outer side, an opening 15 is also provided on the side of the power unit frame 1 near the filter capacitor 41, thereby achieving better heat dissipation.

[0117] A frequency converter includes the power unit described above.

[0118] The above are merely preferred embodiments of the present utility model and are not intended to limit the implementation methods and protection scope of the present utility model. Those skilled in the art should realize that any equivalent substitutions and obvious changes made based on the description and illustrations of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A power unit, characterized in that, This includes a control board, a power drive board, and resistor-capacitor boards that are enclosed in and interconnected within a power unit frame. The power drive board and the resistor-capacitor board are disposed above the control board, and the power drive board is provided with a power drive circuit. The control board is equipped with a control circuit corresponding to the power drive circuit. The power drive circuit includes a rectifier module and a drive module; A DC filter circuit is provided on the resistor-capacitor board. The input terminal of the DC filter circuit is connected to the rectifier module, and the output terminal of the DC filter circuit is connected to the drive module. The positive and negative buses of the DC filter circuit coincide when viewed from above.

2. The power unit according to claim 1, characterized in that, The DC filter circuit includes multiple filter capacitors; The filter capacitor is disposed on the upper surface of the resistor-capacitor plate and passes through a pre-set hole on the power unit frame to reach the outside; The leads of the filter capacitor are in the form of bent wire arrays; The conductor bar is provided with screw holes, and the conductor bar is fixed to the resistor-capacitor plate by bolts.

3. The power unit according to claim 2, characterized in that, The power unit frame is equipped with external components; The external component extends upward along the preset hole; The external connector is attached to the outside of the filter capacitor via a clamp.

4. The power unit according to claim 1, characterized in that, The power drive board includes a first power drive board and a second power drive board. The first power drive board and the second power drive board are arranged side by side along the long axis of the power unit frame; One of the power drive circuits is respectively provided on the first power drive board and the second power drive board; The resistive capacitor plate includes a first resistive capacitor plate and a second resistive capacitor plate; The first resistor-capacitor plate and the second resistor-capacitor plate are respectively disposed on the outer side of the first power drive plate and the second power drive plate; One DC filter circuit is respectively provided on the first resistor-capacitor board and the second resistor-capacitor board; The adjacent DC filter circuit and the power drive circuit are connected by a bridging copper busbar; The first power drive board and the second power drive board are respectively connected to the control board below via pins.

5. The power unit according to claim 1, characterized in that, The power driver board is equipped with an integrally packaged PIM-IGBT device; The power drive circuit is integrated into the PIM-IGBT device; A heat sink is soldered on top of the PIM-IGBT device; The heat sink passes through the power unit frame and is exposed to the outside.

6. The power unit according to claim 5, characterized in that, The number of PIM-IGBT devices is two sets; The PIM-IGBT devices are arranged in parallel; The two heat sinks are securely connected to the power unit frame above by heat sink connectors.

7. The power unit according to claim 1, characterized in that, The power unit frame has multiple input / output terminals on its side; The input / output terminals pass through the power unit frame and are connected to the power drive board; The input and output terminals are fixed to the power unit frame by bolts.

8. The power unit according to claim 7, characterized in that, The power unit frame has a fuse fixed on the side near the input / output terminals; The fuse is arranged along the height of the power unit frame, and passes through the power unit frame via a copper busbar and is connected to the power drive board.

9. The power unit according to claim 2, characterized in that, The power unit frame has an opening on the side near the filter capacitor.

10. A frequency converter, characterized in that, Includes the power unit as described in any one of claims 1-9.

Images