Power module and direct current power transmission system

Abstract

The invention relates to a power module and a direct-current power transmission system, the power module is formed by constructing an upper power switch device, a lower power switch device, a direct-current capacitor, a discharge resistor and a multi-level driving circuit, and an upper tube and a lower tube of the power module are arranged in a differentiated manner, namely, the upper power switch device is configured to comprise a universal power switch device. The lower tube comprises a diode enhanced power switch device, and proper driving resistors are respectively configured for the upper tube and the lower tube through a multi-level driving circuit, so that the consistency of dynamic parameters of the upper tube and the lower tube is ensured, and the influence of direct current bias and the like caused by inconsistent device specifications is eliminated as far as possible; therefore, the upper tube and the lower tube can be reliably conducted in turn during normal operation, namely, the power conversion function is realized. According to the scheme, under extreme working conditions of short circuit and the like, surge current can pass through the diode of the diode enhanced power switch device, namely, autonomous shunt protection is realized, and excessive additional devices do not need to be arranged.

Description

Technical Field

[0001] This application relates to the technical field of DC power transmission, and particularly to a power module and a DC power transmission system. Background Art

[0002] In a high-capacity high-voltage direct current (HVDC) power transmission system, the power module is a key component of the system, undertaking the core task of electric energy conversion, and is the core power transmission technology for building a new power system with new energy as the main body.

[0003] To enable the lower switch of the power module to withstand the surge current impact under short-circuit conditions, it is usually necessary to add a thyristor shunt to the power module. In this way, both the cost and weight of the power module are increased, and the failure rate of the power module is also increased. Therefore, traditional power modules have the defects of poor working reliability and economy. Summary of the Invention

[0004] Based on this, in view of the problems of poor working reliability and economy of power modules, it is necessary to provide a power module and a DC power transmission system.

[0005] This application provides a power module, including: an upper power switching device, a lower power switching device, a DC capacitor, a discharge resistor, and a multi-level drive circuit. The upper power switching device includes a general power switching device; the lower power switching device includes a diode-enhanced power switching device. The first end of the general power switching device is connected to the first end of the diode-enhanced power switching device; the discharge resistor is connected in parallel with the DC capacitor, and the first end formed by the parallel connection is connected to the second end of the general power switching device, and the second end formed by the parallel connection is connected to the second end of the diode-enhanced power switching device; the third end of the general power switching device and the third end of the diode-enhanced power switching device are respectively connected to the multi-level drive circuit.

[0006] In one embodiment, the power module further includes a bypass switch. The general power switching device includes a first power switching device. The diode-enhanced power switching device includes a second power switching device and a first diode assembly connected in reverse parallel. The number of multi-level drive circuits is two;

[0007] The first end of the first power switching device is connected to the first end of the second power switching device and the first end of the bypass switch. The second end of the first power switching device is connected to the first end formed by the parallel connection. The second end of the second power switching device is connected to the second end formed by the parallel connection and the second end of the bypass switch; the third end of the first power switching device and the third end of the second power switching device are respectively connected to one of the multi-level drive circuits.

[0008] In one embodiment, the power module further includes a bypass switch. The general power switch device includes a first power switch device and a third power switch device. The diode-enhanced power switch device includes a second power switch device and a first diode assembly connected in reverse parallel, and a fourth power switch device and a second diode assembly connected in reverse parallel. The number of multi-level drive circuits is four;

[0009] A first end of the first power switch device is connected to a first end of the second power switch device and a first end of the bypass switch. A first end of the third power switch device is connected to a first end of the fourth power switch device and a second end of the bypass switch. A second end of the first power switch device and a second end of the third power switch device are respectively connected to a first end formed by the parallel connection. A second end of the second power switch device and a second end of the fourth power switch device are respectively connected to a second end formed by the parallel connection. A third end of the first power switch device, a third end of the second power switch device, a third end of the third power switch device, and a third end of the fourth power switch device are respectively connected to one of the multi-level drive circuits.

[0010] In one embodiment, the voltage rating of the general power switch device is 6.5 KV, and the voltage rating of the diode-enhanced power switch device is 6.5 KV.

[0011] In one embodiment, the diode-enhanced power switch device is formed by integrally pressing a power switch device and a diode assembly.

[0012] In one embodiment, the multi-level drive circuit includes an FPGA, a plurality of parallel turn-on branches, and a plurality of parallel turn-off branches. The turn-on branch includes a turn-on switch and a turn-on resistor. A control end of the turn-on switch is connected to the FPGA. An input end of the turn-on switch is connected to the positive power supply terminal. An output end of the turn-on switch is connected to a third end of the power switch device through the turn-on resistor. The turn-off branch includes a turn-off switch and a turn-off resistor. A control end of the turn-off switch is connected to the FPGA. An input end of the turn-off switch is connected to the negative power supply terminal. An output end of the turn-off switch is connected to a third end of the power switch device through the turn-off resistor.

[0013] In one embodiment, the power module further includes an insulation protection plate and a heat dissipation device. The insulation protection plate is disposed between the upper power switch device and the heat dissipation device, and / or, the insulation protection plate is disposed between the lower power switch device and the heat dissipation device.

[0014] In one embodiment, the general power switch device is a general IGBT device, and the diode-enhanced power switch device is a diode-enhanced IGBT device.

[0015] In one of the embodiments, the power module further includes a laminated busbar and a heat sink, and the laminated busbar is disposed between the DC capacitor and the heat sink.

[0016] The present application also provides a direct current transmission system, comprising a converter valve constructed using any of the power modules described above.

[0017] The power module and the DC power transmission system are constructed by an upper power switch device, a lower power switch device, a DC capacitor, a discharge resistor and a multi-level drive circuit to form a power module. The upper tube and the lower tube of the power module are set differently, that is, the upper power switch device is configured to include a general power switch device, and the lower tube is configured to include a diode-enhanced power switch device. The upper tube and the lower tube are respectively configured with appropriate drive resistors through a multi-level drive circuit to ensure the consistency of the dynamic parameters of the upper tube and the lower tube, and to eliminate the influence of DC bias caused by inconsistent device specifications as much as possible, so that the upper tube and the lower tube can be reliably turned on in turn during normal operation, that is, the power conversion function is realized. This solution, by setting the upper tube and the lower tube differently, and the lower tube adopts a diode-enhanced power switch device, so that under extreme conditions such as short circuit, the surge current can pass through the diode of the diode-enhanced power switch device, that is, autonomous shunt protection is realized, without setting too many additional devices, optimizing device utilization, and thus effectively improving the working reliability and economy of the power module. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 This is a schematic diagram of the structure of a power module in an embodiment of the present application;

[0020] Figure 2 This is a schematic diagram of the structure of a power module in another embodiment of the present application;

[0021] Figure 3 This is a schematic diagram of the structure of a power module in another embodiment of the present application;

[0022] Figure 4 This is a schematic diagram of the structure of a multi-level driving circuit in an embodiment of the present application;

[0023] Figure 5 Schematic diagram of the chip layout of a general IGBT in an embodiment of the present application;

[0024] Figure 6 Schematic diagram of the chip layout of a diode-enhanced IGBT in an embodiment of the present application;

[0025] Figure 7 Schematic diagram of the diode junction temperature under short-circuit conditions of a general IGBT in an embodiment of the present application;

[0026] Figure 8 Schematic diagram of the diode junction temperature under short-circuit conditions of a diode-enhanced IGBT in an embodiment of the present application. Detailed implementation manners

[0027] To facilitate the understanding of the present application, the present application will be described more comprehensively below with reference to the relevant accompanying drawings. Preferred embodiments of the present application are shown in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the understanding of the disclosure of the present application more thorough and comprehensive.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs. The terms used in the description of this application herein are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0029] It can be understood that the terms "first", "second", etc. used in this application can be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish the first element from another element. For example, without departing from the scope of this application, the first resistor can be called the second resistor, and similarly, the second resistor can be called the first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor.

[0030] It can be understood that "connection" in the following embodiments should be understood as "electrical connection", "communication connection", etc. if there is an electrical signal or data transfer between the connected circuits, modules, units, etc.

[0031] It can be understood that "at least one" means one or more, and "a plurality" means two or more. "At least part of an element" means part or all of the element.

[0032] As used herein, the singular forms "a", "an" and "the" may also include the plural forms unless the context clearly dictates otherwise. It should also be understood that the terms "comprising", "including" or "having" and the like specify the presence of the stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof. At the same time, the term "and / or" used in this specification includes any and all combinations of the related listed items.

[0033] The power module provided by the embodiment of the present application can be applied to a DC power transmission system and can be specifically used anywhere in the DC power transmission system where there is a need for power conversion, without specific limitation. In one embodiment, the power module can be used in the converter valve of the DC power transmission system. For example, it can be used in the switching capacitor module of the MCC (Modular Commutated Converter) converter valve or the arm module of the MCC converter valve. In other embodiments, the power module can also be used in other types of converter valves, which can be specifically selected according to actual needs.

[0034] Please refer to Figure 1 , the present application provides a power module, including: an upper power switching device 101, a lower power switching device 103, a DC capacitor C, a discharge resistor R, and a multi-level drive circuit 105. The upper power switching device 101 includes a general power switching device; the lower power switching device 103 includes a diode-enhanced power switching device. The first end of the general power switching device is connected to the first end of the diode-enhanced power switching device; the discharge resistor R is connected in parallel with the DC capacitor C, and the first end formed by the parallel connection is connected to the second end of the general power switching device, and the second end formed by the parallel connection is connected to the second end of the diode-enhanced power switching device; the third end of the general power switching device and the third end of the diode-enhanced power switching device are respectively connected to the multi-level drive circuit 105.

[0035] Specifically, the general power switching device is the power switching device commonly used in general circuits, which usually does not have an additional diode or only has a small number of diodes. The diode-enhanced power switching device refers to a power switching device that is configured with more additional diodes compared to the general power switching device to enhance its surge protection ability. That is, compared to the general power switching device, the diode-enhanced power switching device is configured with more additional diodes to enhance its performance. The multi-level drive circuit 105 is a drive circuit that can configure different levels of drive resistors for the third end (i.e., the control end) of the power switching device.

[0036] In the technical solution of this application, considering that the upper switch (i.e., the upper power switching device 101) and the lower switch (i.e., the lower power switching device 103) of the power module both use devices of the same specification and cannot optimize the performance for different working conditions, the upper power switching device 101 and the lower power switching device 103 are set differently. Further considering that after the upper and lower switches are set differently, dynamic parameters will be inconsistent, causing a series of problems, a multi-level drive circuit 105 is configured to drive the power switching devices. By connecting different levels of drive resistors through the multi-level drive circuit 105, reliable alternate conduction of the upper and lower switches is achieved, ensuring the consistency of the dynamic parameters of the upper and lower switches.

[0037] In this way, a power module is formed by the upper power switching device 101, the lower power switching device 103, the DC capacitor C, the discharge resistor R, and the multi-level drive circuit 105. The upper and lower switches of the power module are set differently. That is, the upper power switching device 101 is configured to include a general power switching device, and the lower switch is configured to include a diode-enhanced power switching device. And appropriate drive resistors are respectively configured for the upper and lower switches through the multi-level drive circuit 105 to ensure the consistency of the dynamic parameters of the upper and lower switches, and to eliminate as much as possible the influence such as DC bias caused by inconsistent device specifications, so as to achieve reliable alternate conduction of the upper and lower switches during normal operation, that is, to achieve the power conversion function. In this solution, by setting the upper and lower switches differently, and using a diode-enhanced power switching device for the lower switch, in extreme working conditions such as short circuit, the surge current can pass through the diode of the diode-enhanced power switching device, that is, autonomous shunt protection is achieved, without setting too many additional devices, optimizing the device utilization rate, and thus effectively improving the working reliability and economy of the power module.

[0038] Please refer to Figure 2 , in one embodiment, the power module further includes a bypass switch S. The general power switching device includes a first power switching device Q1. The diode-enhanced power switching device includes a second power switching device Q2 and a first diode component (not shown in the figure) connected in reverse parallel. The number of multi-level drive circuits 105 (not shown in the figure) is two;

[0039] The first end of the first power switching device Q1 is connected to the first end of the second power switching device Q2 and the first end of the bypass switch S. The second end of the first power switching device Q1 is connected to the first end formed by parallel connection. The second end of the second power switching device Q2 is connected to the second end formed by parallel connection and the second end of the bypass switch S. The third ends of the first power switching device Q1 and the second power switching device Q2 are respectively connected to a multi-level drive circuit 105.

[0040] Specifically, in the solution of this embodiment, the power module is a half-bridge power module, and a bypass switch S is configured to protect the power module. Further, the first end and the second end of the bypass switch S can be used as the input ends of the power module to be cascaded with other power modules, so as to form various sub-modules to meet the requirements of the DC transmission scenario.

[0041] Please refer to Figure 3 , in one embodiment, the power module further includes a bypass switch S. The general power switch device includes a first power switch device Q1 and a third power switch device Q3. The diode-enhanced power switch device includes a second power switch device Q2 and a first diode component (not shown in the figure) connected in reverse parallel, and a fourth power switch device Q4 and a second diode component (not shown in the figure) connected in reverse parallel. The number of multi-level drive circuits 105 (not shown in the figure) is four;

[0042] The first end of the first power switch device Q1 is connected to the first end of the second power switch device Q2 and the first end of the bypass switch S. The first end of the third power switch device Q3 is connected to the first end of the fourth power switch device Q4 and the second end of the bypass switch S. The second ends of the first power switch device Q1 and the third power switch device Q3 are respectively connected to the first ends formed by parallel connection. The second ends of the second power switch device Q2 and the fourth power switch device Q4 are respectively connected to the second ends formed by parallel connection. The third ends of the first power switch device Q1, the second power switch device Q2, the third power switch device Q3, and the fourth power switch device Q4 are respectively connected to a multi-level drive circuit 105.

[0043] Specifically, different from the above embodiment, in this embodiment, the power module is a full-bridge power module, and a bypass switch S is configured to protect the power module. Similarly, the first end and the second end of the bypass switch S can be used as the input ends of the power module to be cascaded with other power modules, so as to form various sub-modules to meet the requirements of the DC transmission scenario.

[0044] In one embodiment, the voltage level of the general power switch device is 6.5 KV, and the voltage level of the diode-enhanced power switch device is 6.5 KV.

[0045] Specifically, the voltage level of 6.5 KV means that it can withstand a high voltage of 6.5 KV (kilovolts). In existing DC transmission projects, power devices with voltage levels of 3.3 kV and 4.5 kV are generally used. Therefore, in a DC transmission system, a large number of power devices need to be connected in series to meet the high-voltage transmission requirements. The large number of series-connected power devices results in a complex structure of the converter valve formed by the power module, a large volume and high cost of the converter valve. The large volume places higher requirements on engineering design and space layout, and the manufacturing cost and installation cost of the converter valve increase significantly.

[0046] The power switching devices with a voltage rating of 6.5 kV have the advantages of fewer module numbers, smaller volume, lighter weight, lower cost, and higher reliability. They can be further promoted and applied to the construction and upgrading of power systems to improve the stability, reliability, and flexibility of the power grid. They can be promoted in urban power grids and microgrids, thereby improving the flexibility, stability, and controllability of urban power grids, and providing technical support for urban power grids to cope with sudden power demand fluctuations, handle faults, and support local energy systems.

[0047] Therefore, in the solution of this embodiment, power switching devices with a voltage rating of 6.5 kV (that is, both the general power switching device and the diode-enhanced power switching device are 6.5 kV) are adopted. In this way, in the high-voltage DC transmission scenario with the same voltage rating, the number of converter valve modules can be greatly reduced, the size of the converter valve and the volume of the valve hall can be reduced, the operating loss of the converter valve can be reduced, the investment cost can be reduced, and the operating economy can be improved.

[0048] In one embodiment, the diode-enhanced power switching device is formed by integrally pressing a power switching device and a diode component.

[0049] Specifically, integral pressing means pressing the power switching device and the diode component together to form an integral diode-enhanced power switching device. By means of integral pressing, the commutation path can be reduced and the stray inductance can be reduced. At the same time, the volume of the power module can be further reduced.

[0050] It can be understood that in other embodiments, it can also be the way of independently pressing the power switching device and the diode component to form a diode-enhanced power switching device, and specific selection can be made according to actual requirements.

[0051] Please refer to Figure 4 , in one embodiment, the multi-level drive circuit 105 includes an FPGA, multiple parallel turn-on branches, and multiple parallel turn-off branches. The turn-on branch includes a turn-on switch (that is, T1-Tn shown in the figure) and a turn-on resistor (that is, Ron1-Ronn shown in the figure). The control end of the turn-on switch is connected to the FPGA, the input end of the turn-on switch is connected to the positive power supply terminal, and the output end of the turn-on switch is connected to the third terminal (that is, G shown in the figure) of the power switching device through the turn-on resistor. The turn-off branch includes a turn-off switch (that is, B1-Bn shown in the figure) and a turn-off resistor (that is, Roff1-Roffn shown in the figure). The control end of the turn-off switch is connected to the FPGA, the input end of the turn-off switch is connected to the negative power supply terminal, and the output end of the turn-off switch is connected to the third terminal of the power switching device through the turn-off resistor.

[0052] Specifically, the turn-on branch is the branch used to control the conduction of the power switch device, and the turn-off branch is the branch used to control the turn-off of the power switch device. FPGA, namely Field Programmable Gate Array, internally includes three parts: Configurable Logic Block (CLB), Input Output Block (I / O module), and Interconnect. By reconfiguring the logic module and I / O module inside the FPGA, the user's logic can be implemented.

[0053] Using the multi-level drive circuit 105 and selecting the optimal resistance drive resistors (i.e., turn-on resistor and turn-off resistor) to be inserted at different stages of turn-on or turn-off can greatly optimize the switching performance of the power switch device. Figure 4 As shown, the switch matrix of the multi-level drive circuit 105 (i.e., the turn-on switch of the turn-on branch and the turn-off switch of the turn-off branch) is composed of MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors). T1 - Tn are the MOSFETs responsible for turn-on, and B1 - Bn are the MOSFETs responsible for turn-off. The drive resistance for turning on the power switch device can be obtained by paralleling any combination of Ron1 - Ronn. Similarly, the drive resistance for turning on the power switch device can be obtained by paralleling any combination of Roff1 - Roffn. Therefore, 2 n -1 kinds of drive resistance values can be obtained for both turn-on and turn-off.

[0054] Furthermore, in another embodiment, the multi-level drive circuit 105 further includes a main path switch, the main path switch T_BOOST, whose input terminal is connected to the power supply (i.e., the shown +Vge_BOOST), the output terminal is connected to the third terminal of the power switch device, and the control terminal is connected to the controller (which can be an FPGA or others, and is not specifically limited).

[0055] In the above solution, the multi-level drive circuit 105 built with an FPGA realizes the digital drive of the power switch device. Only by modifying the code can the differential configuration drive of the upper transistor and the lower transistor be achieved on the same hardware version, ensuring the consistency of the dynamic parameters of the upper transistor and the lower transistor, and having high configuration flexibility.

[0056] In one of the embodiments, the power module further includes an insulation protection plate and a heat dissipation device. The insulation protection plate is disposed between the upper power switch device 101 and the heat dissipation device, and / or the insulation protection plate is disposed between the lower power switch device 103 and the heat dissipation device.

[0057] Specifically, the heat dissipation device, i.e., the device used to dissipate heat from the power switch device, can be a water-cooled heat dissipation device, specifically, the water pipe in the water-cooled heat dissipation device for storing water. In the solution of this embodiment, considering that power switch devices with a relatively high voltage level such as 6.5 KV are used, the power density of the power module will be higher. Under extreme working conditions, the housing of the power switch device may crack or even generate flying objects. Therefore, in the solution of this embodiment, an insulating protection plate can be configured at the place where the upper power switch device 101 is close to the heat dissipation device and / or at the place where the lower power switch device 103 is close to the heat dissipation device, so as to enhance the insulation and explosion-proof capabilities of the power module and prevent the broken housing from splashing and damaging the surrounding components.

[0058] In one embodiment, the general power switch device is a general IGBT device, and the diode-enhanced power switch device is a diode-enhanced IGBT device.

[0059] Specifically, IGBT, i.e., Insulated Gate Bipolar Transistor, combines the advantages of BJT (Bipolar Junction Transistor) and MOSFET (Metal Oxide Semiconductor Field Effect Transistor). The on and off of the IGBT are controlled by controlling the gate voltage. When the gate voltage is higher than the turn-on voltage, the MOSFET part inside the IGBT conducts, thereby driving the BJT part to conduct, making the IGBT as a whole in the on state. On the contrary, when the gate voltage is lower than the turn-on voltage, the MOSFET part inside the IGBT turns off, and the BJT part also turns off accordingly, making the IGBT as a whole in the off state.

[0060] Furthermore, in one embodiment, the general IGBT device is a general 6.5 KV IGBT device. Specifically, it can be referred to in combination with Figure 5 , which uses a 6500V / 2000A (ampere) press-pack IGBT and includes 16 IGBT chips inside, and 8 anti-parallel diode chips (i.e., the so-called F shown in the figure) are built-in. The diode-enhanced IGBT device is a diode-enhanced 6.5 KV IGBT device. Please refer to Figure 6 , which uses a 6500V / 2000A press-pack IGBT and includes 16 IGBT chips inside, and 20 anti-parallel diode chips (i.e., the so-called F shown in the figure) are integrally press-packed.

[0061] It can be understood that in other embodiments, the power switch device adopted in the general power switch device and the diode-enhanced power switch device can also be formed by building an Integrated Gate Commutated Thyristor (IGCT) with a voltage of 6.5 kV together with a clamping circuit. It can be specifically selected according to actual requirements and will not be limited herein.

[0062] In one embodiment, the power module further includes a laminated busbar and a heat dissipation device, and the laminated busbar is arranged between the DC capacitor C and the heat dissipation device.

[0063] Specifically, considering that when the power module is working, the stray inductance in the commutation loop affects the module peak voltage stress, the short-circuit protection tolerance of the power switch device, and the explosion-proof ability of the extreme voltage and current module. Therefore, by analyzing the device commutation path in the power module, the laminated busbar can be used to connect the main power devices, that is, the DC capacitor C and the heat dissipation device are connected through the laminated busbar. In this way, the parasitic inductance of the power module can be reduced.

[0064] Furthermore, in a more detailed embodiment, a laminated busbar with a smaller inductance value can be used to connect the DC capacitor C and the heat dissipation device. For example, a laminated busbar with an inductance less than 150 nH (nanohenry) can be used. In this way, the overall parasitic inductance of the power module can be controlled at about 114 nH (nanohenry), achieving the balance of turn-off overvoltage and capacitor discharge peak current.

[0065] Aiming at the problems of the existing large-capacity flexible DC converter valve, such as low voltage level, many module numbers, large valve volume, high cost, and the need to additionally increase device shunting in the face of extreme working conditions, the solution of the embodiment of the present application adopts higher-specification devices to improve the module voltage level, and through the differential configuration of the upper and lower tube devices, optimizes the device utilization rate, realizing that no additional shunting devices are required in extreme working conditions such as surge short circuit.

[0066] For example, for a certain converter valve project, 6.5 kV IGBTs are used for the differential configuration of the upper and lower tubes. Compared with the original power module of the 4.5 kV IGBT type, the number of series modules of the converter valve is reduced, the system complexity is reduced, the volume and weight are reduced, and the cost is reduced. The specific comparison is as follows:

[0067]

[0068] And, it can be referred to in combination with Figure 7 and Figure 8, the lower transistor uses a diode-enhanced 6.5 kV / 2 kA IGBT device. When passing through the surge current under short-circuit conditions, the maximum junction temperature of a general-purpose 6.5 kV / 2 kA IGBT device is 495 °C (degrees Celsius), and the diode is damaged. It is necessary to increase the thyristor shunt; the maximum junction temperature of the diode-enhanced IGBT device is only 175 °C, and the diode can withstand it. There is no need to install a thyristor shunt, which improves the reliability and reduces the module cost.

[0069] This application also provides a DC power transmission system, including a converter valve formed by building the power modules described in any of the above.

[0070] Specifically, the structure and type of the converter valve are not unique. It can be an MCC converter valve, etc. The type of the DC power transmission system is not unique either. It can be a high-voltage DC power transmission system or an extra-high-voltage DC power transmission system, etc. There is no specific limitation.

[0071] In this solution, by differentially setting the upper and lower transistors in the power module of the converter valve, and using a diode-enhanced power switch device for the lower transistor, in extreme conditions such as short circuits, the surge current can pass through the diode of the diode-enhanced power switch device, that is, autonomous shunt protection is achieved. There is no need to set up too many additional devices, optimizing the device utilization rate, and thus effectively improving the operation reliability of the DC power transmission system.

[0072] In the description of this specification, the descriptions referring to terms such as "some embodiments" and "other embodiments" mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example.

[0073] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0074] The above-described embodiments only represent several implementation manners of the present application. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several deformations and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A power module, characterized in that: include: The upper power switch device includes a general power switch device; A lower power switch device, comprising a diode-enhanced power switch device, wherein a first end of the universal power switch device is connected to a first end of the diode-enhanced power switch device; DC capacitors; A discharge resistor connected in parallel with the DC capacitor, with a first end formed in parallel connected to the second end of the general power switch device, and a second end formed in parallel connected to the second end of the diode enhanced power switch device; A multi-level driving circuit, the third end of the universal power switch device and the third end of the diode enhanced power switch device are respectively connected to the multi-level driving circuit.

2. The power module according to claim 1, characterized in that: The power module further includes a bypass switch, the general power switch device includes a first power switch device, the diode enhanced power switch device includes a second power switch device and a first diode component connected in reverse parallel, and the number of the multi-level drive circuits is two; The first end of the first power switch device is connected to the first end of the second power switch device and the first end of the bypass switch, the second end of the first power switch device is connected to the first end formed in parallel, and the second end of the second power switch device is connected to the second end formed in parallel and the second end of the bypass switch; the third end of the first power switch device and the third end of the second power switch device are respectively connected to one of the multi-level drive circuits.

3. The power module according to claim 1, characterized in that: The power module further includes a bypass switch, the general power switch device includes a first power switch device and a third power switch device, the diode enhanced power switch device includes a second power switch device and a first diode component connected in reverse parallel, and a fourth power switch device and a second diode component connected in reverse parallel, and the number of the multi-level drive circuits is four; The first end of the first power switch device is connected to the first end of the second power switch device and the first end of the bypass switch, the first end of the third power switch device is connected to the first end of the fourth power switch device and the second end of the bypass switch, the second end of the first power switch device and the second end of the third power switch device are respectively connected to the first end formed in parallel, the second end of the second power switch device and the second end of the fourth power switch device are respectively connected to the second end formed in parallel; the third end of the first power switch device, the third end of the second power switch device, the third end of the third power switch device and the third end of the fourth power switch device are respectively connected to one of the multi-level drive circuits.

4. The power module according to claim 1, characterized in that: The voltage level of the general power switch device is 6.5KV, and the voltage level of the diode enhanced power switch device is 6.5KV.

5. The power module according to claim 2 or 3, characterized in that: The diode-enhanced power switch device is formed by integrally pressing a power switch device and a diode assembly.

6. The power module according to any one of claims 1 to 4, characterized in that: The multi-level driving circuit includes an FPGA, multiple parallel open branches and multiple parallel closed branches, the open branch includes an open switch and an open resistor, the control end of the open switch is connected to the FPGA, the input end of the open switch is connected to the positive end of the power supply, the output end of the open switch is connected to the third end of the power switch device through the open resistor, the closed branch includes a closed switch and a closed resistor, the control end of the closed switch is connected to the FPGA, the input end of the closed switch is connected to the negative end of the power supply, and the output end of the closed switch is connected to the third end of the power switch device through the closed resistor.

7. The power module according to any one of claims 1 to 4, characterized in that: The power module further comprises an insulating protection plate and a heat sink, wherein the insulating protection plate is arranged between the upper power switch device and the heat sink, and / or the insulating protection plate is arranged between the lower power switch device and the heat sink.

8. The power module according to any one of claims 1 to 4, characterized in that: The general power switch device is a general IGBT device, and the diode-enhanced power switch device is a diode-enhanced IGBT device.

9. The power module according to any one of claims 1 to 4, characterized in that: The power module further comprises a laminated busbar and a heat sink, wherein the laminated busbar is arranged between the DC capacitor and the heat sink.

10. A direct current transmission system, characterized in that: It comprises a converter valve constructed by using the power module described in any one of claims 1-9.

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