CN116367492A - Power module and frequency converter - Google Patents

Abstract

The application relates to a power module and a frequency converter, wherein the power module comprises a frame and a power module arranged on the frame. The power module also includes a heat exchanger disposed on the frame, the heat exchanger having a first side and a second side disposed opposite in a first direction. The power module comprises a diode unit and an IGBT unit, wherein the diode unit is arranged on the first side of the heat exchanger, and the IGBT unit is arranged on the second side of the heat exchanger. Wherein the heat exchanger is configured for heat exchanging the diode unit and the IGBT unit by means of a cooling liquid. According to the power module, the diode unit and the IGBT unit are respectively arranged on the first side and the second side of the heat exchanger, and heat exchange can be carried out on the diode unit and the IGBT unit by means of the heat exchanger, so that heat exchange efficiency is improved. Moreover, the heat exchanger performs heat exchange by means of the cooling liquid, so that the heat exchange efficiency can be further improved with smaller volume, and the protection level is improved.

Description

Power module and frequency converter

Technical Field

The application relates to the technical field of frequency converters, in particular to a power module and a frequency converter.

Background

The frequency converter is a power control device which controls the alternating current motor by changing the frequency of a working power supply of the motor by applying a frequency conversion technology and a microelectronic technology. The frequency converter in the related art mostly dissipates heat through an air cooling mode, however, as the power level of the frequency converter is continuously improved, the heat exchange efficiency of the air cooling mode is lower, and the actual working condition requirement is difficult to meet.

Disclosure of Invention

Based on this, provide a can be through improving heat exchange efficiency's power module and converter to adapt to the converter of higher capacity, satisfy the heat dissipation demand of converter.

In one aspect of the present application, a power module is provided, including a frame and a power module mounted on the frame;

the power module further includes a heat exchanger disposed on the frame, the heat exchanger having a first side and a second side disposed opposite in a first direction;

the power module comprises a diode unit and an IGBT unit;

a diode unit provided at the first side of the heat exchanger; and

an IGBT unit provided on the second side of the heat exchanger;

wherein the heat exchanger is configured for heat exchanging the diode unit and the IGBT unit by means of a cooling liquid.

In one embodiment, the IGBT cells are configured in a patch type structure.

In one embodiment, the diode unit is constructed in a patch type structure.

In one embodiment, the power module further comprises a support capacitor;

the frame is provided with an accommodating space, and the supporting capacitor is arranged on the frame and is positioned in the accommodating space.

In one embodiment, the support capacitor has a body portion and a connection portion;

the connecting part is arranged on the body part along a second direction so as to be connected with the frame;

the second direction is perpendicular to the first direction.

In one embodiment, the power module further includes a capacitor busbar; the capacitor busbar is electrically connected with the supporting capacitor;

defining a plane perpendicular to the second direction as a reference plane, wherein the positive row and the negative row of the capacitor busbar are symmetrically arranged by taking the reference plane as a center;

the second direction is perpendicular to the first direction.

In one embodiment, the power module further comprises a dc link bank;

the direct current connection row is electrically connected between the diode unit and the capacitor busbar.

In one embodiment, the power module further comprises a dc link bank;

the direct current connection row is electrically connected between the IGBT unit and the capacitor busbar.

In one embodiment, the power module further comprises a housing;

the shell is covered outside the power module along the first direction and is connected with the frame.

In another aspect of the present application, a frequency converter is provided, including the above power module.

The power module and the frequency converter at least comprise a frame, a power module and a heat exchanger. By providing the diode unit and the IGBT unit in the power module on the first side and the second side of the heat exchanger, respectively, the diode unit and the IGBT unit can be heat-exchanged simultaneously by means of the heat exchanger, thereby improving heat exchange efficiency. Moreover, the heat exchanger performs heat exchange by means of the cooling liquid, so that the heat exchange efficiency can be further improved with smaller volume, and the protection level is improved.

Drawings

FIG. 1 is a schematic diagram of a power module according to an embodiment of the present disclosure;

FIG. 2 is a schematic diagram of a power module according to an embodiment of the disclosure;

fig. 3 is a schematic structural diagram of another view of a power module according to an embodiment of the present application.

Reference numerals illustrate:

100. a power module; 110. a frame; 111. an upper beam body; 120. a power module; 121. a diode unit; 122. an IGBT unit; 130. a heat exchanger; 131. a first side; 132. a second side; 140. a supporting capacitor; 141. binding posts; 150. a capacitor busbar; 160. a direct current connection row; 165. a unit output row; 170. a housing; 180. a driving module; 190. outputting copper bars; x, a first direction; z, second direction.

Detailed Description

In order to make the above objects, features and advantages of the present application more comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. This application is, however, susceptible of embodiment in many other forms than those described herein and similar modifications can be made by those skilled in the art without departing from the spirit of the application, and therefore the application is not to be limited to the specific embodiments disclosed below.

In the description of the present application, it should be understood that the terms "center," "longitudinal," "transverse," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," etc. indicate orientations or positional relationships based on the orientation or positional relationships shown in the drawings, are merely for convenience in describing the present application and simplifying the description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be configured and operated in a particular orientation, and therefore should not be construed as limiting the present application.

Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present application, the meaning of "plurality" is at least two, such as two, three, etc., unless explicitly defined otherwise.

In this application, unless specifically stated and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. The specific meaning of the terms in this application will be understood by those of ordinary skill in the art as the case may be.

In this application, unless expressly stated or limited otherwise, a first feature "up" or "down" a second feature may be the first and second features in direct contact, or the first and second features in indirect contact via an intervening medium. Moreover, a first feature being "above," "over" and "on" a second feature may be a first feature being directly above or obliquely above the second feature, or simply indicating that the first feature is level higher than the second feature. The first feature being "under", "below" and "beneath" the second feature may be the first feature being directly under or obliquely below the second feature, or simply indicating that the first feature is less level than the second feature.

It will be understood that when an element is referred to as being "fixed" or "disposed" on another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and the like are used herein for illustrative purposes only and are not meant to be the only embodiment.

Further, the drawings are not 1:1, and the relative dimensions of the various elements are drawn by way of example only in the drawings and are not necessarily drawn to true scale.

In order to facilitate understanding of the technical solution of the present application, before the detailed description, a description is first made of a power module and a frequency converter in the related art.

A Variable-frequency Drive (VFD) is a power control device that applies a frequency conversion technique and a microelectronics technique to control an ac motor by changing a frequency of a motor operating power supply. The medium-high voltage power unit is applied to the fields of electric power, metallurgy, water supply, petroleum, chemical industry, coal and the like, which need energy conservation and improvement of production process. In the 80 s of the 20 th century, frequency converter technology has been increasingly used as an energy saving technology in major industrialized countries. In China, the high-voltage frequency converter is applied to few industries such as electric power, metallurgy and the like from the later 90 th century, the speed regulation of the high-voltage frequency converter is currently becoming a main flow speed regulation mode of a high-voltage alternating current motor, the energy-saving effect of using a high-voltage frequency conversion system by new projects and technology improvement projects is obvious, and great progress is made in the aspects of power, reliability, efficiency, cost and the like.

With the increasing power of power electronics, the capacity of the frequency converter is increasing, and the design of a heat dissipation system becomes a key problem. The design quality of the heat dissipation system of the frequency converter directly influences whether the frequency converter can safely and stably work for a long time. The heating of the frequency converter is mostly from a power device, the power device is sensitive to temperature, and the change of the temperature can influence the switching of the device. If the capability of the heat dissipation system is insufficient as the power dissipated by the IGBT increases, the temperature of the chip may reach or even exceed the junction temperature, which may cause the IGBT to fail.

Among them, IGBT (Insulated Gate Bipolar Transistor), i.e., an insulated gate bipolar transistor, is a compound semiconductor device composed of a MOSFET (insulated gate field effect transistor) and a BJT (bipolar transistor). The selection of power switching devices is particularly important as the core of the main circuit of the frequency converter. The IGBT has the advantages of high input impedance, high working speed, low on-state voltage, high current carrying capacity, easy driving and the like, so that the IGBT is widely applied and is an ideal full-control device. The turn-on and turn-off of the IGBT is controlled by the gate voltage. When a positive voltage is applied to the gate, a channel is formed in the MOSFET and provides a base current for the PNP transistor, thereby turning on the IGBT. At this time from N ⁺ Region implant into N ^- Hole (minority) pair N of region ^- The region is subjected to conductivity modulation, so that the resistance of the N region is reduced, and the IGBT with high blocking voltage also has low on-state voltage drop. When negative voltage is applied to the gate, the channel in the MOSFET disappears, the base current of the PNP transistor is cut off, and the IGBT is turned off.

The heat dissipation mode in the related art mostly adopts air cooling heat dissipation. With the continuous improvement of integration and power level of power modules, conventional air-cooled heat dissipation has faced a dilemma that a large amount of heat is not easily and rapidly dissipated in a short time in a limited space. And the fan that high-power device needs is relatively bulky, can lead to noise increase, dust increase, wind pressure increase, reduces the stability of system. Therefore, it has become increasingly difficult for conventional forced air cooling to meet the heat dissipation requirements of high power IGBT modules. The capacity of the air cooling frequency converter in the related art is generally smaller than 17MW, and the capacity working condition of the frequency converter with the capacity of more than 17MW is difficult to meet.

The inventor researches show that the water heat conductivity coefficient of the water-cooled radiator is far higher than that of wind due to the fact that the specific heat capacity of water is large, the volume and noise of the water-cooled radiator are relatively small. Therefore, it is necessary to provide a power module and a frequency converter capable of improving the heat dissipation effect by using a water cooling method.

For convenience of description, the drawings show only structures related to the embodiments of the present application.

FIG. 1 is a schematic diagram of a power module 100 according to an embodiment of the present application;

fig. 2 shows a schematic structural diagram of the power module 120 in an embodiment of the present application.

Referring to fig. 1 in combination with fig. 2, a power module 100 according to an embodiment of the present application includes a frame 110 and a power module 120 mounted on the frame 110. The power module 100 further includes a heat exchanger 130 disposed on the frame 110, the heat exchanger 130 having a first side 131 and a second side 132 disposed opposite along the first direction x. The power module 120 includes a diode unit 121 and an IGBT unit 122, the diode unit 121 is disposed on a first side 131 of the heat exchanger 130, and the IGBT unit 122 is disposed on a second side 132 of the heat exchanger 130. Wherein the heat exchanger 130 is configured for heat exchanging the diode unit 121 and the IGBT unit 122 by means of a cooling liquid.

In the power module 100, the diode unit 121 and the IGBT unit 122 in the power module 120 are respectively disposed on the first side 131 and the second side 132 of the heat exchanger 130, so that the diode unit 121 and the IGBT unit 122 can be simultaneously heat-exchanged by the heat exchanger 130, thereby improving heat exchange efficiency. Furthermore, the heat exchanger 130 performs heat exchange by means of the cooling liquid, and can further improve heat exchange efficiency and protection level with a smaller volume.

The IGBT unit 122 is combined as an inverter circuit, and the diode unit 121 is combined as a rectifier circuit. The rectification inversion electrical structure formed in this way not only optimizes the volume, improves the heat dissipation efficiency, but also reduces the cost. In the embodiment of the present application, the power module 120 is composed of two IGBT cells 122 and three diode cells 121. Illustratively, the heat exchanger 130 is a water-cooled radiator.

As shown in fig. 2, in some embodiments, IGBT cells 122 are configured in a patch-type structure. The chip-type structure is a power semiconductor device structure in the form of a chip-type package. The IGBT cell 122 of the patch structure is disposed on the side surface of the heat exchanger 130 by means of a paste, and the IGBT cell 122 is in close contact with the side surface of the heat exchanger 130. As can be appreciated, the body of the IGBT cell 122 is kept in contact with the side surface of the heat exchanger 130, and there is no gap or distance between the body and the side surface of the heat exchanger 130, which greatly improves the heat exchange efficiency. Meanwhile, the device adopting the chip-on-package mode generally has a smaller volume, so that the volume of the power module 120 is further reduced. Illustratively, the IGBT cells 122 are secured to the second side 132 of the heat exchanger 130 by a bolt assembly.

As shown in fig. 2, in some embodiments, the diode unit 121 is configured as a patch structure. The chip-type structure is a power semiconductor device structure in the form of a chip-type package. The diode unit 121 of the patch structure is disposed on the side surface of the heat exchanger 130 by means of a paste, and the diode unit 121 is in close contact with the side surface of the heat exchanger 130. As can be appreciated, the body of the diode unit 121 is kept in contact with the side surface of the heat exchanger 130, and there is no gap or distance from the side surface of the heat exchanger 130, thereby greatly improving heat exchange efficiency. Meanwhile, the device adopting the chip-on-package mode generally has a smaller volume, so that the volume of the power module 120 is further reduced. Illustratively, the diode unit 121 is secured to the first side 131 of the heat exchanger 130 by a bolt assembly.

Fig. 3 is a schematic diagram illustrating a structure of another view of the power module 100 according to an embodiment of the present application.

As shown in connection with fig. 1 and 3, in some embodiments, the power module 100 further includes a support capacitor 140. The frame 110 has a receiving space, and the supporting capacitor 140 is mounted on the frame 110 and located in the receiving space. In this way, the supporting capacitor 140 is fixed in the accommodating space on the frame 110, so that the installation is more stable, the space of the frame 110 can be reasonably utilized, the whole power module 100 is more compact, and the layout of components is more reasonable. In particular, in some embodiments, the supporting capacitor 140 has a body portion and a connection portion, and the connection portion is disposed on the body portion along the second direction z to be connected to the frame 110. The second direction z is perpendicular to the first direction x. In this way, the connecting portion provided in the main body portion along the second direction z can be more reliably fixed to the frame 110 without damaging the main body portion of the support capacitor 140. Specifically, the connecting portions include two connecting portions, which are disposed at both ends of the body portion at intervals from each other along the second direction z, respectively. In this way, the supporting capacitor 140 can be fixed by means of two connecting parts in the second direction z, so that the stability of the fixation is further ensured. Illustratively, the connection is secured to the frame 110 by means of a bolt assembly. Specifically, the plurality of connection parts are fixedly connected to the upper beam 111 and the lower beam of the frame 110, respectively.

As shown in fig. 3, in some embodiments, the power module 100 further includes a capacitor busbar 150, and the capacitor busbar 150 is electrically connected to the supporting capacitor 140. Wherein, a plane perpendicular to the second direction z is defined as a reference plane, and the positive row and the negative row of the capacitor busbar 150 are symmetrically arranged with the reference plane as a center. The second direction z is perpendicular to the first direction x. It will be appreciated that the positive and negative rows of the capacitor busbar 150 are arranged in a positive-to-negative arrangement. In this way, the structural layout of the positive and negative rows of the capacitor busbar 150 is more compact and reasonable while the electrical safety distance is ensured, so that the volume of the power module 100 is further reduced. Specifically, the supporting capacitor 140 is provided with a binding post 141 in a protruding manner, and the positive and negative rows of the capacitor busbar 150 are respectively mounted on the binding post 141.

For the dynamic parameter test platform of the IGBT cell 122, the stray inductance of the commutation loop during the switching transient of the device, which is often referred to as the test platform stray inductance for short, is an important factor affecting the device parameters. The different stray inductances have an important influence on the on-off characteristics of the IGBT cells 122. Under the same working condition, the increase of the loop stray inductance can slow down the turn-on speed of the IGBT unit 122, the current collecting rising rate is reduced, the turn-on transient current peak is obviously reduced, and the non-uniformity is reduced. As shown in fig. 3, in some embodiments, the power module 120 further includes a dc link bank 160, and the dc link bank 160 is electrically connected between the IGBT cell 122 and the capacitor busbar 150. Thus, by stacking the dc link banks 160 one above the other, the current flows in opposite directions, which ensures that the stray inductance meets the requirements, and the operating space is more suitable. Specifically, IGBT cell 122 is electrically connected to capacitor busbar 150 through a set of positive and negative dc connection rows 160. In some embodiments, the power module 120 further includes a dc link bar 160, and the dc link bar 160 is electrically connected between the diode unit 121 and the capacitor busbar 150. In this way, it can be further ensured that the stray inductance meets the requirements. Specifically, the diode unit 121 is electrically connected to the capacitor busbar 150 through a set of positive and negative dc connection rows 160.

It should be noted that the dc link bank 160 is used for connection conduction inside the power module 120. The power module 100 further includes ac connection banks and unit output banks 165, the ac connection banks and unit output banks 165 being for connection and conduction with external devices. Specifically, after the IGBT cell 122 and the diode cell 121 are mounted on the heat exchanger 130, the dc link line 160, the ac link line, and the cell output line 165 are mounted. Therefore, the current-carrying load can be met, the stray inductance is smaller, in addition, the insulation effect is more reliable, and the cost is relatively lower. Further, the power module 100 further includes an output copper bar 190, and the output copper bar 190 is connected to the unit output bar 165.

Referring again to fig. 1, in some embodiments, the power module 100 further includes a housing 170. The housing 170 is disposed outside the power module 120 along the first direction x, and is connected to the frame 110. In this way, the housing 170 can provide protection for the power module 120, and the power module 120 is accommodated in the space between the housing 170 and the frame 110, so that the power module 100 is modularized, the space is reasonably utilized, the volume is reduced, and the maintenance and the overhaul are easy. Further, a heat exchanger 130 is also accommodated between the housing 170 and the frame 110. In this way, the space in the housing 170 can be reasonably utilized while ensuring reliable heat dissipation of the IGBT unit 122 and the diode unit 121 by the heat exchanger 130, and the volume of the power module 100 can be further reduced.

The driving module 180 is an interface between the controller and the power device, and has the functions of providing isolation, reliable driving capability, protection and the like. The driving module 180 with excellent performance not only can enable the IGBT unit 122 to be rapidly switched between a cut-off area and a saturation area and improve the efficiency of the power electronic converter system, but also can enable the IGBT unit 122 to timely exit from a fault state when the IGBT unit 122 is in fault, so that the damage of the IGBT unit 122 is reduced, and the service life of the IGBT unit 122 is prolonged. As shown in fig. 3, in some embodiments, the power module 100 further includes a driving module 180, the driving module 180 being configured to drive the IGBT cells 122 on and off. Specifically, the driving module 180 is mounted to the frame 110 by means of a bolt assembly. It should be noted that the modules and units in the power module 100 are turned on by means of copper bar connections.

Based on the same inventive concept, in another aspect of the present application, a frequency converter is further provided, including the power module 100 described above. The frequency converter mainly improves the flexibility of the alternating current motor power supply, namely the frequency and the amplitude of the frequency converter can be changed, the period of a moving magnetic field of the frequency converter can be changed accordingly, and further smooth control of the motor rotating speed is achieved. The frequency converter mainly comprises a rectifying circuit, an intermediate link circuit, an inverter circuit, a control circuit and a protection circuit. The IGBT unit 122 is a core component of the frequency converter, and is mainly used for inverting direct current into alternating current for load. According to the power module 100 provided by the embodiment of the application, the heat exchanger 130 is used for radiating the heat of the IGBT unit 122 and the diode unit 121, so that the heat radiation efficiency of the power module 100 is greatly improved, and the frequency converter using the power module 100 is improved in heat radiation efficiency, and the heat radiation requirement of the frequency converter is met.

Referring to fig. 1 to 3, in the power module 100 and the frequency converter provided in the embodiments of the present application, the diode unit 121 and the IGBT unit 122 in the power module 120 are respectively disposed on the first side 131 and the second side 132 of the heat exchanger 130, so that the heat exchange can be performed on the diode unit 121 and the IGBT unit 122 by means of the heat exchanger 130 at the same time, thereby improving the heat exchange efficiency, having higher power density, and reasonable circuit distribution. Furthermore, the heat exchanger 130 performs heat exchange by means of the cooling liquid, and can further improve heat exchange efficiency and protection level with a smaller volume. The IGBT unit 122 is combined as an inverter circuit, and the diode unit 121 is combined as a rectifier circuit. The rectification inversion electrical structure formed in this way not only optimizes the volume, improves the heat dissipation efficiency, but also reduces the cost.

The IGBT cells 122 and diode cells 121 of the patch structure are held in contact with the side surfaces of the heat exchanger 130 without gaps and distances from the side surfaces of the heat exchanger 130, thereby greatly improving heat exchange efficiency. Meanwhile, the device adopting the chip-on-package mode generally has a smaller volume, so that the volume of the power module 120 is further reduced. The connection portion of the supporting capacitor 140 can be more reliably fixed to the frame 110, and the body portion of the supporting capacitor 140 is not damaged. The positive row and the negative row of the capacitor busbar 150 are arranged in a positive-to-negative way, so that the structural layout of the positive row and the negative row of the capacitor busbar 150 is more compact and reasonable while the electric safety distance is ensured, and the size of the power module 100 is further reduced. The IGBT unit 122 is electrically connected to the capacitor busbar 150 by a set of positive and negative dc connection lines 160, and the diode unit 121 is electrically connected to the capacitor busbar 150 by another set of positive and negative dc connection lines 160, and the current flows in opposite directions, so that the stray inductance can be ensured to meet the requirement, and the operation space is more suitable. The housing 170 covering the power module 120 along the first direction x can provide protection for the power module 120.

Through the space between the shell 170 and the frame 110 and the accommodating space of the frame 110, the power module 120, the heat exchanger 130 and other module devices can be installed in a planning layout, so that the power module 100 is modularized, and the power module can be independently installed, detached and maintained. The frequency converter using the power module 100 has improved heat dissipation efficiency, and meets the heat dissipation requirement of the frequency converter.

The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.

The above examples only represent a few embodiments of the present application, which are described in more detail and are not to be construed as limiting the scope of the claims. It should be noted that it would be apparent to those skilled in the art that various modifications and improvements could be made without departing from the spirit of the present application, which would be within the scope of the present application. Accordingly, the scope of protection of the present application is to be determined by the claims appended hereto.

Claims (10)

1. The power module is characterized by comprising a frame and a power module arranged on the frame;

the power module further includes a heat exchanger disposed on the frame, the heat exchanger having a first side and a second side disposed opposite in a first direction;

the power module comprises a diode unit and an IGBT unit;

a diode unit provided at the first side of the heat exchanger; and

an IGBT unit provided on the second side of the heat exchanger;

wherein the heat exchanger is configured for heat exchanging the diode unit and the IGBT unit by means of a cooling liquid.

2. The power module of claim 1, wherein the IGBT cells are configured in a patch-type structure.

3. The power module of claim 1, wherein the diode unit is configured as a patch structure.

4. A power module according to any of claims 1-3, further comprising a support capacitor;

the frame is provided with an accommodating space, and the supporting capacitor is arranged on the frame and is positioned in the accommodating space.

5. The power module of claim 4, wherein the support capacitor has a body portion and a connection portion;

the connecting part is arranged on the body part along a second direction so as to be connected with the frame;

the second direction is perpendicular to the first direction.

6. The power module of claim 4, further comprising a capacitor busbar; the capacitor busbar is electrically connected with the supporting capacitor;

defining a plane perpendicular to the second direction as a reference plane, wherein the positive row and the negative row of the capacitor busbar are symmetrically arranged by taking the reference plane as a center;

the second direction is perpendicular to the first direction.

7. The power module of claim 6, further comprising a dc link bank;

the direct current connection row is electrically connected between the diode unit and the capacitor busbar.

8. The power module of claim 6, further comprising a dc link bank;

the direct current connection row is electrically connected between the IGBT unit and the capacitor busbar.

9. A power module according to any one of claims 1-3, further comprising a housing;

the shell is covered outside the power module along the first direction and is connected with the frame.

10. A frequency converter comprising a power module as claimed in any one of claims 1-9.

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