CN219740193U - Power device assembly and frequency converter - Google Patents

Abstract

The utility model discloses a power device assembly and a frequency converter, wherein the power device assembly comprises a substrate, a discrete device group and a motherboard, the discrete device group comprises power devices of an inverter circuit, a power wiring is arranged on the motherboard, and the power wiring is connected with a positive direct current bus of the inverter circuit in parallel. According to the power device component provided by the embodiment of the utility model, parasitic inductance can be reduced, so that bus voltage peak when the power device is turned off is reduced, and turn-off loss and EMI interference of the power device are reduced.

Description

Power device assembly and frequency converter

Technical Field

The utility model relates to the technical field of frequency converters, in particular to a power device assembly and a frequency converter.

Background

Currently, a PIM (Power integrated module) or IPM (Intelligent power module) module is mostly adopted as a frequency converter power device in the multi-split air conditioner industry, however, the price of a PIM or IPM module is high, the productivity is limited, and the problems of stock shortage and the like are caused. Secondly, the PIM or IPM module same module is designed with larger margin for covering different industries at the same time, so that the problem of over-design of various parameters in partial application occasions such as air conditioner and the like is caused. Finally, packaging of integrated modules sacrifices back-end product design flexibility, product parameter configuration, etc., is often subject to upstream suppliers.

The discrete device is used as a material commonly used in the power electronics field in the market, and has the advantages of low price and stable goods source. The discrete devices are circulated in the market, and the different parameter specifications are more in variety, so that the design requirements of different application occasions can be almost met. The PCB wiring design using the discrete device is relatively flexible, and engineers can inject different design concepts according to product needs, so as to solve various problems in engineering technology.

In the related art, parasitic inductance of the PIM module is large, resulting in increased loss when the power module is turned off, thereby increasing loss of the frequency converter.

Disclosure of Invention

The present utility model aims to solve at least one of the technical problems in the related art to some extent.

It is therefore an object of the present utility model to provide a power device assembly that reduces parasitic inductance, thereby reducing bus voltage spikes when the power device is turned off, reducing power device turn-off losses, and EMI interference.

Another object of the present utility model is to propose a frequency converter comprising a power device assembly as described above.

According to the power device assembly in the embodiment of the utility model, the power device assembly comprises a substrate, a discrete device group and a motherboard, wherein the discrete device group comprises power devices of an inverter circuit, a power wiring is arranged on the motherboard, and the power wiring is connected with a positive direct current bus of the inverter circuit in parallel.

According to the power device component provided by the embodiment of the utility model, parasitic inductance can be reduced, so that bus voltage peak when the power device is turned off is reduced, and turn-off loss and EMI interference of the power device are reduced.

In addition, the power device assembly according to the above embodiment of the present utility model may further have the following additional technical features:

optionally, the substrate includes a bottom surface layer, an insulating layer, a heat conducting layer and a surface layer, and in a thickness direction of the substrate, the bottom surface layer, the insulating layer, the heat conducting layer and the surface layer are sequentially stacked, wherein the surface layer includes a welding area and a solder resist area.

Optionally, the surface layer is provided with a first hollowed-out area, the heat conducting layer constructs the welding area on the surface opposite to the first hollowed-out area, and the heat conducting layer is partially overlapped with the welding-resisting area in the projection of the thickness direction of the substrate.

Optionally, the inverter circuit includes an upper bridge circuit and a lower bridge circuit, the power device of the inverter circuit is disposed on the welding area, and the first electrical connection portion of the power device in the upper bridge circuit and the second electrical connection portion of the power device in the lower bridge circuit are close to each other.

Optionally, the upper bridge circuit includes a first power device, a third power device and a fifth power device, the heat conduction layer includes a first heat conduction area, and projections of welding areas corresponding to the first power device, the third power device and the fifth power device in the thickness direction of the substrate are all in the first heat conduction area.

Optionally, the lower bridge circuit includes a second power device, a fourth power device and a sixth power device, the heat conduction layer includes a second heat conduction area, a fourth heat conduction area and a sixth heat conduction area, the welding area includes a second welding subarea corresponding to the second power device, a fourth welding subarea corresponding to the fourth power device and a sixth welding subarea corresponding to the sixth power device, a projection of the second welding subarea in a thickness direction of the substrate is in the second heat conduction area, a projection of the fourth welding subarea in the thickness direction of the substrate is in the fourth heat conduction area, and a projection of the sixth welding subarea in the thickness direction of the substrate is in the sixth heat conduction area.

Optionally, the distance between every two of the second welding area, the fourth welding area and the sixth welding area in the width direction of the substrate is greater than a first preset distance.

Optionally, the surface layer is further provided with a second hollow area, the second hollow area is connected with the first hollow area, the heat conduction layer constructs a diversion area on the surface opposite to the second hollow area, and the area of the diversion area is smaller than that of the welding area.

Optionally, the discrete device group further includes a pin and a thermistor, the welding area further includes a plurality of seventh welding subareas, the pin is disposed on the plurality of seventh welding subareas, and two ends of the thermistor are respectively connected with any two of the seventh welding subareas.

Optionally, a minimum distance between the thermistor and the edge of the substrate is greater than a second preset distance.

Optionally, the power device assembly further includes a coolant radiator, where the coolant radiator is connected with the bottom layer and is disposed below the bottom layer, and a projection of the bottom layer on the thickness direction of the substrate is located in the coolant radiator.

Alternatively, the substrate is configured in an arc shape at a side edge opposite to the gravitational direction.

Optionally, the thickness of the insulating layer is 0.1-0.2 mm, and the thickness of the welding area is 60-100 micrometers.

According to the frequency converter provided by the embodiment of the utility model, the frequency converter comprises the power device assembly.

According to the frequency converter provided by the embodiment of the utility model, the parasitic inductance in the frequency converter can be reduced by applying the power device assembly, so that the bus voltage peak when the power device is turned off is reduced, and the turn-off loss and the EMI interference of the power device are reduced.

Drawings

Fig. 1 is a bottom view of a power device assembly in some embodiments of the utility model.

Fig. 2 is a schematic structural view of a substrate according to some embodiments of the utility model.

Fig. 3 is a schematic diagram of a power device assembly in some embodiments of the utility model.

Fig. 4 is a bottom view of a power device assembly in further embodiments of the utility model.

Reference numerals:

the power device assembly 100, the substrate 10, the positive direct current bus 11, the bottom layer 12, the insulating layer 13, the heat conducting layer 14, the first heat conducting area 141, the second heat conducting area 142, the fourth heat conducting area 143, the sixth heat conducting area 144, the surface layer 15, the welding area 151, the first welding sub-area 1511, the second welding sub-area 1512, the third welding sub-area 1513, the fourth welding sub-area 1514, the fifth welding sub-area 1515, the sixth welding sub-area 1516, the seventh welding sub-area 1517, the solder resist area 152, the current conducting area 153, the discrete device group 20, the first electrical connection 21a, the second electrical connection 21b, the pins 22, the thermistor 23, the motherboard 30, the power trace 31, and the coolant heat sink 40.

Detailed Description

The present utility model provides a power device assembly 100 and a frequency converter that can reduce parasitic inductance, thereby reducing bus voltage spikes when the power device is turned off, reducing power device turn-off loss, and EMI interference (i.e., electromagnetic interference).

Embodiments of the present utility model are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative and intended to explain the present utility model and should not be construed as limiting the utility model.

As shown in fig. 1 and fig. 3, according to the power device assembly 100 in the embodiment of the present utility model, the power device assembly 100 may be used in a frequency converter, and a circuit in the power device assembly 100 may include an inverter circuit to convert direct current in the frequency converter into alternating current, and the inverter circuit may be combined with a rectifying circuit, a filtering circuit, etc. to implement a change of a frequency of a motor operating circuit, so as to achieve an energy saving effect.

The power device assembly 100 may include a substrate 10, a discrete device group 20, and a motherboard 30.

The discrete device group 20 includes power devices of the inverter circuit, the motherboard 30 is provided with a power trace 31, and the power trace 31 is connected in parallel with the positive dc bus 11 of the inverter circuit, so that parasitic inductance in the power device assembly 100 can be reduced, and power loss of the circuit can be reduced.

Specifically, the substrate 10 may be provided with an inverter circuit, by disposing the power device on the substrate 10 to convert direct current into alternating current, and the pins of the power device may be electrically connected with the power trace 31 on the motherboard 30, so that the power trace 31 on the motherboard 30 may be parallel connected with the positive dc bus 11 of the inverter circuit, it may be understood that, since the power trace 31 is parallel connected with the positive dc bus 11 of the inverter circuit, the parasitic inductance generated by the power trace 31 is parallel connected with the parasitic inductance generated by the positive dc bus 11, so that the total parasitic inductance generated by the power trace 31 and the positive dc bus 11 is reduced, and the effects of reducing the bus voltage peak when the power device is turned off, and reducing the turn-off loss and EMI interference of the power device are achieved.

The inverter circuit may include a single-phase inverter circuit and a multi-phase inverter circuit, and a three-phase inverter circuit is described below as an example unless otherwise specified.

For example, the power device may be an IGBT (i.e. insulated gate bipolar transistor) and include a plurality of power devices, and in the three-phase inverter circuit, the collectors of the adjacent power devices of the upper bridge circuit may be electrically connected to the bus bars, in other words, the collectors of the adjacent power devices of the upper bridge circuit may be electrically connected to the bus bars, while the pins of the power devices may be electrically connected to the power trace 31 on the motherboard 30, so that the bus bars may be connected in parallel to the power trace 31, and parasitic inductance generated by the inverter circuit is reduced, so as to reduce the voltage peak of the bus bars when the power devices are turned off, and reduce the turn-off loss and EMI interference effects of the power devices.

As shown in fig. 1 to 3, in some embodiments of the present utility model, the substrate 10 may include a bottom layer 12, an insulating layer 13, a heat conducting layer 14, and a surface layer 15, and in the thickness direction of the substrate 10, the bottom layer 12, the insulating layer 13, the heat conducting layer 14, and the surface layer 15 are sequentially stacked, where the surface layer 15 includes a soldering region 151 and a solder resist region 152, so that the discrete device group 20 may be stably disposed on the substrate 10, and it is ensured that the frequency converter may operate normally.

The soldering region 151 on the substrate 10 may be provided with various electrical components, which may include a thermistor 23, a power device, and the like.

Alternatively, the power device may be disposed on the substrate 10 through the welding area 151, and meanwhile, the power device may be electrically connected with the welding area 151, so that the power device may be connected into the inverter circuit to implement current conversion of the inverter circuit, and the surface layer 15 is provided with the solder resist area 152, so that the circuit on the substrate 10 is prevented from being electrically connected with the external environment through the solder resist area 152, and short circuit and other phenomena may be avoided. In addition, when the power device assembly 100 works, the power device arranged on the surface layer 15 can radiate heat through the substrate 10, and the heat of the power device can be transferred according to the sequence of the surface layer 15, the heat conducting layer 14, the insulating layer 13 and the bottom layer 12, so that the heat radiation of the power device is realized, and the influence of the overhigh temperature on the normal operation of the power device is avoided.

In addition, the bottom layer 12 may be metal, the heat conducting layer 14 may be copper foil, so as to improve the heat dissipation effect of the substrate 10 on the power devices, and part of the power devices may be electrically connected through the copper foil, so that a plurality of power devices may form an inverter circuit, so as to realize the normal operation of the frequency converter.

Further, the surface layer 15 may be provided with a first hollowed-out area, the heat conducting layer 14 constructs a welding area 151 on a surface opposite to the first hollowed-out area, and the heat conducting layer 14 and the welding-resisting area 152 are partially overlapped by projection in the thickness direction of the substrate 10, so as to improve the heat dissipation effect of the power device; it can be appreciated that the surface layer 15 may be laminated on the heat conducting layer 14, and a first hollowed-out area may be provided on the surface layer 15, so that a part of the heat conducting layer 14 may be exposed, and a part of the heat conducting layer 14 may be a welding area 151 for welding an electrical component, so that the electrical component may be fixed on the substrate 10; in addition, the heat conducting layer 14 and the solder mask area 152 are partially laminated, in other words, another part of the heat conducting layer 14 may be laminated under the surface layer 15, so that the area of the heat conducting layer 14 may be larger than that of the solder mask area 151.

As shown in fig. 2 and 4, in some embodiments of the present utility model, the inverter circuit may include an upper bridge circuit and a lower bridge circuit, and the power devices of the inverter circuit are disposed on the welding area 151, wherein the first electrical connection portion 21a of the power devices in the upper bridge circuit and the second electrical connection portion 21b of the power devices in the lower bridge circuit are close to each other, so that the length of the power trace 31 on the motherboard 30 may be reduced to improve the integration level of the power device assembly 100 and save the cost.

For ease of description, the power devices in the upper bridge circuit may be defined as a first power device group and the power devices in the lower bridge circuit may be defined as a second power device group.

Specifically, in the power device assembly 100, the electrical connection portions of the plurality of power devices may be electrically connected to the power traces 31 on the motherboard 30, that is, the electrical connection portions of the plurality of power devices may be electrically connected to each other through the power traces 31 on the motherboard 30 so that the plurality of power devices form a part of the inverter circuit, so that, on the substrate 10, the line length between the first electrical connection portion 21a and the second electrical connection portion 21b connected to the motherboard 30 may be reduced by providing the first electrical connection portion 21a of the first power device group toward the second electrical connection portion 21b of the second power device group, and providing the second electrical connection portion 21b of the second power device group toward the first electrical connection portion 21a of the first power device group, so that the line length between the first electrical connection portion 21a and the second electrical connection portion 21b connected to the motherboard 30 may be reduced, thereby improving the integration of the power device assembly 100 and saving the manufacturing cost.

For example, the electrical connection may be a pin of a power device; specifically, the pins of the plurality of power devices may be connected to the power traces 31 on the motherboard 30, and at this time, the pins of the first power device group and the pins of the second power device group may be close to each other, so that the length of the power traces 31 between the first power device group and the second power device group may be reduced, so as to save cost.

For another example, the electrical connection part may be a pad connected to a pin of the power device on the circuit board, so that the plurality of power devices may be connected to the positive dc bus 11 respectively; specifically, the bonding pad connected to the pin of the first power device group and the bonding pad connected to the pin of the second power device group may be brought close to each other, so that the length of the positive dc bus 11 may be reduced to save costs.

As shown in fig. 1 and 2, in some embodiments of the present utility model, the upper bridge circuit may include a first power device, a third power device, and a fifth power device, and the heat conductive layer 14 may include a first heat conductive region 141, and projections of the welding regions 151 corresponding to the first power device, the third power device, and the fifth power device in the thickness direction of the substrate 10 are all within the first heat conductive region 141, so that the heat dissipation effect and the integration level of the power device assembly 100 may be improved.

The welding area 151 may include a first welding sub-area 1511 corresponding to a first power device, a third welding sub-area 1513 corresponding to a third power device, and a fifth welding sub-area 1515 corresponding to a fifth power device.

In detail, in combination with the foregoing embodiment, the heat conducting layer 14 may be copper foil, and the welding areas 151 corresponding to the first power device, the third power device and the fifth power device respectively are located in the first heat conducting area 141 along the projection of the thickness direction of the substrate 10, and the first heat conducting area 141 of the heat conducting layer 14 may connect the first welding sub-area 1511, the third welding sub-area 1513 and the fifth welding sub-area 1515 in series in order to facilitate the operation of the inverter circuit on the power device assembly 100, and meanwhile, by this arrangement, the integration level of the power device assembly 100 may be improved.

Additionally, the first thermally conductive region 141 may include one or more; for example, the first heat conductive region 141 may include one, along the projection of the substrate 10 in the thickness direction, the first welding sub-region 1511, the third welding sub-region 1513 and the fifth welding sub-region 1515 are all located in the first heat conductive region 141, and when the power device assembly 100 operates, the heat conductive layer 14 located in the first heat conductive region 141 may directly guide the heat generated when the first power device, the third power device and the fifth power device operate to the bottom layer 12, so as to improve the heat dissipation efficiency of the discrete device group 20 while ensuring the connection strength of the power device and the substrate 10; for another example, the first heat conduction region 141 may include a plurality of first heat conduction regions 141, and the first welding sub-region 1511, the third welding sub-region 1513, and the fifth welding sub-region 1515 may respectively correspond to three first heat conduction regions 141 one by one along the projection of the thickness direction of the substrate 10, and a plurality of first heat conduction regions 141 may be disposed between adjacent welding sub-regions, so as to connect the adjacent first heat conduction regions 141 together, so as to increase the areas of the first heat conduction regions 141 corresponding to the first power device, the third power device, and the fifth power device; alternatively, the first heat conductive region 141, the third heat conductive region, and the fifth heat conductive region may be disposed, so that the first solder sub-region 1511, the third solder sub-region 1513, and the fifth solder sub-region 1515 may be in one-to-one correspondence, respectively, so that the heat dissipation effect of the discrete device group 20 may be improved. This is not to be construed as limiting the scope of the utility model.

Next, along the projection of the thickness direction of the substrate 10, the total area of the first heat conduction region 141 may be not smaller than the sum of the areas of the first welding sub-region 1511, the third welding sub-region 1513 and the fifth welding sub-region 1515, so that when the power device operates, the heat generated by the power device can be transferred through the heat conduction layer 14 as much as possible, and the heat dissipation effect of the discrete device group 20 is improved. In addition, in order to ensure the heat dissipation effect of the discrete device group 20, the total area of the first heat conduction region 141 may be 1.1 to 2 times as large as the sum of the areas of the first, third and fifth solder subregions 1511, 1513 and 1515, so as to facilitate better heat dissipation of the discrete device group 20.

As shown in fig. 1 and 2, in some embodiments of the present utility model, the lower bridge circuit may include a second power device, a fourth power device, and a sixth power device, the heat conductive layer 14 may include a second heat conductive region 142, a fourth heat conductive region 143, and a sixth heat conductive region 144, the welding region 151 includes a second welding sub-region 1512 corresponding to the second power device, a fourth welding sub-region 1514 corresponding to the fourth power device, and a sixth welding sub-region 1516 corresponding to the sixth power device, a projection of the second welding sub-region 1512 in a thickness direction of the substrate 10 is within the second heat conductive region 142, a projection of the fourth welding sub-region 1514 in the thickness direction of the substrate 10 is within the fourth heat conductive region 143, and a projection of the sixth welding sub-region 1516 in the thickness direction of the substrate 10 is within the sixth heat conductive region 144, and thus, a heat dissipation effect of the discrete device group 20 may be improved, and an influence on a normal operation of the frequency converter due to an excessive temperature may be avoided.

Wherein, in combination with the foregoing embodiment, the power device may be an IGBT, the collector of the second power device may be electrically connected to the second welding sub-region 1512, the collector of the fourth power device may be electrically connected to the fourth welding sub-region 1514, and the collector of the sixth power device may be electrically connected to the sixth welding sub-region 1516.

When the power device assembly 100 operates, the second power device may be welded to the second welding sub-region 1512, the fourth power device may be welded to the fourth welding sub-region 1514, the sixth power device may be welded to the sixth welding sub-region 1516, and the projection along the thickness direction of the substrate 10, the second welding sub-region 1512 may be located in the second heat conducting region 142, the fourth welding sub-region 1514 may be located in the fourth heat conducting region 143, the sixth welding sub-region 1516 may be located in the sixth heat conducting region 144, and in combination with the foregoing embodiment, the area of the heat conducting region is larger than that of the welding sub-region, so that the heat transfer amount of the heat conducting layers 14 corresponding to the second power device, the fourth power device and the sixth power device may be increased, respectively, to improve the heat dissipation efficiency of the discrete device group 20.

In addition, in the lower bridge circuit, the collector connection parts of the second power device, the fourth power device and the sixth power device are respectively and correspondingly and electrically connected with the emitter terminals of the first power device, the third power device and the fifth power device of the upper bridge circuit, so that a certain distance can be spaced between adjacent heat conduction areas in the lower bridge circuit, damage such as circuit short circuit is avoided, and the use safety of the frequency converter is ensured.

Further, the distance between the second, fourth and sixth welding sub-regions 1512, 1514 and 1516 in the width direction of the substrate may be greater than the first preset distance, and the width direction is perpendicular to the first direction, so that the electrical components may be prevented from being ignited and damaging the hardware circuit.

Wherein, the first, third and fifth welding subregions 1511, 1513 and 1515 may be sequentially arranged at intervals in the width direction, and the second, fourth and sixth welding subregions 1512, 1514 and 1516 may be sequentially arranged at intervals in the width direction. The first predetermined distance is the shortest path between two conductive parts or between a conductive part and a device protection interface measured along the insulating surface.

Specifically, when the frequency converter works, since the insulating material around the conductor is electrically polarized, the insulating material is electrified, and according to the lower bridge circuit of the three-phase inverter circuit, in order to avoid mutual electrical connection among the second power device, the fourth power device and the sixth power device, the distance between the second welding subarea 1512, the fourth welding subarea 1514 and the sixth welding subarea 1516 can be larger than a first preset distance, and the first preset distance can be 0.6 mm-0.7 mm, alternatively, the first preset distance can be 0.63 mm.

Further, the distance between the first, third and fifth welding sub-regions 1511, 1513, 1515 in the width direction may be larger than the first preset distance, so as to avoid the power devices welded on the first, third and fifth welding sub-regions 1511, 1513, 1515 from being ignited and damaging the hardware circuit.

In some embodiments of the present utility model, as shown in fig. 1, the surface layer 15 is further provided with a second hollowed-out area.

The second hollow area can be connected with the first hollow area, the heat conduction layer constructs a flow guiding area 153 on the surface opposite to the second hollow area, and the area of the flow guiding area 153 is smaller than that of the welding area 151, so that tin balls extruded when the power device is welded on the welding area 151 are prevented from being sputtered on the board surface, and damage such as short circuit and the like of the inverter circuit is avoided.

The surface layer can be provided with a second hollow area, so that a diversion area is formed on the surface of the heat conduction layer opposite to the second hollow area, and diversion of welding materials is facilitated when the power device is welded in the welding area; specifically, the flow guiding area 153 may be connected to the edge of the welding area 151, when the power device is welded on the welding area 151, the power device may be placed on the welding area 151 coated with a welding material such as solder paste, and the solder paste is heated to be melted, after the solder paste is cooled and solidified, a welding spot may be formed between the welding area 151 and the power device, in this process, the flow guiding area 153 may drain the melted welding material into the flow guiding area 153, so that the welding material is prevented from being extruded and sputtered onto the board surface during the welding process, and the inverter circuit on the power device assembly 100 is prevented from being shorted.

As shown in fig. 1, in some embodiments of the present utility model, the discrete device group 20 may further include a pin 22 and a thermistor 23, the soldering region 151 may further include a plurality of seventh soldering subregions 1517, the pin 22 is disposed on the plurality of seventh soldering subregions 1517, and two ends of the thermistor 23 may be respectively connected to any two of the seventh soldering subregions 1517, so that the power device assembly 100 may be electrically connected to an external electrical component through the pin 22 to provide over-temperature protection for the power device assembly 100.

Optionally, four seventh welding sub-areas 1517 are provided on the substrate 10, the four seventh welding sub-areas 1517 may be arranged on the substrate 10 in a rectangular array, the pins 22 are all welded on the four seventh welding sub-areas 1517, any two of the four seventh welding sub-areas 1517 may be electrically connected with two ends of the thermistor 23 respectively, specifically, the thermistor 23 may be electrically connected with the pins 22 to convert a resistance signal into a temperature signal, when the inverter circuit works, the resistance of the thermistor 23 may change with the temperature on the substrate 10, and the pins 22 may be electrically connected with external electrical components, so that the temperature signal may be transmitted to the external electrical components, so that a user may control the temperature of the power device assembly 100 within a predetermined range, and the temperature of the power device assembly 100 is prevented from exceeding the predetermined range, thereby affecting the normal work of the frequency converter.

In addition, the sum of the areas of the seventh welding sub-areas 1517 may be twice or three times the actual area of the pins 22 in the seventh welding sub-areas 1517, so that the push-pull resistance of the pins 22 may be improved, so as to ensure that the pins 22 may be stably disposed on the substrate 10, and avoid the pins 22 from being separated from the substrate 10 due to multiple plugging and unplugging of the pins 22 with external electrical components.

In some embodiments of the present utility model, the minimum distance between the thermistor 23 and the edge of the substrate 10 may be greater than a second predetermined distance; optionally, the second preset distance may be 5 mm, so that the risk of short circuit and the like of the inverter circuit in the power device assembly 100 can be avoided, and the use safety of a user is ensured.

As shown in fig. 3, in some embodiments of the present utility model, the power device assembly 100 may further include a coolant heat sink 40.

The coolant radiator 40 is connected to the bottom layer 12 and disposed below the bottom layer 12, and a projection of the bottom layer 12 in the thickness direction of the substrate 10 is located in the coolant radiator 40, so as to improve the heat dissipation efficiency of the substrate 10.

When the power device assembly 100 operates, heat generated by the operation of the discrete device group 20 can be sequentially transferred from the surface layer 15, the heat conduction layer 14 and the bottom layer 12, and then the refrigerant radiator 40 arranged below the bottom layer 12 can exchange heat with the bottom layer 12 to radiate heat of the bottom layer 12, so that the operation temperature of the discrete device group 20 is controlled within a preset range, and the influence of the overhigh temperature of the discrete device group 20 on the normal operation of the frequency converter is avoided.

As shown in fig. 1, in some embodiments of the present utility model, the edge of the substrate 10 on the side opposite to the gravity direction is configured as an arc shape, so as to guide the condensed water generated on the substrate 10, and prevent the condensed water from flowing to the surface of the substrate 10, thereby causing a short circuit on the substrate 10.

In detail, the refrigerant radiator 40 is disposed below the bottom layer 12 to radiate heat from the bottom layer 12 of the substrate 10 in a refrigerant phase change manner, in this process, the refrigerant radiator 40 absorbs heat on the substrate 10, so that condensed water can be generated at the edge of the substrate 10, and at this time, in order to guide the condensed water conveniently, so as to avoid the condensed water flowing onto the board surface of the substrate 10 and causing the inverter circuit to be shorted, the edge of the substrate 10 at one side opposite to the gravity direction can be configured into an arc shape, so that the condensed water can flow from the edge of the substrate 10 under the action of gravity, and then leaves the substrate 10, thereby ensuring the electricity safety of the frequency converter.

In some embodiments of the present utility model, the thickness of the insulating layer 13 is 0.1-0.2 mm, alternatively, the thickness of the insulating layer 13 may be 0.15 mm to insulate the discrete device group 20 from the coolant radiator 40, to prevent the coolant radiator 40 from generating condensed water, resulting in a short circuit of the substrate 10, and in addition, the thickness of the soldering region 151 is 60-100 μm, alternatively, the thickness of the soldering region 151 may be 70 mm to improve the connection strength of the discrete device group 20 and the pins 22, etc. with the soldering region 151, so that the discrete device, etc. electrical components may be stably fixed on the substrate 10.

According to the frequency converter in the embodiment of the utility model, the frequency converter comprises the power device assembly 100 in the embodiment, so that parasitic inductance in the frequency converter can be reduced by applying the power device assembly 100, and bus voltage peak, power device turn-off damage and electromagnetic interference can be reduced when the power device is turned off.

Specifically, pins of the plurality of power devices of the inverter circuit may be electrically connected to the power trace 31 on the motherboard 30, and meanwhile, the first power device, the third power device and the fifth power device of the upper bridge circuit may be welded to the first welding sub-area 1511, the third welding sub-area 1513 and the fifth welding sub-area 1515 in a one-to-one correspondence manner, and the first heat conduction area 141 may be equivalently the positive dc bus 11 of the inverter circuit, and the first welding sub-area 1511, the third welding sub-area 1513 and the fifth welding sub-area 1515 may be electrically connected through the first heat conduction area 141, so that the collector of the first power device is electrically connected to the collector of the third power device, and the collector of the third power device is electrically connected to the collector of the fifth power device, in other words, the power trace 31 on the motherboard 30 may be connected in parallel to the positive dc bus 11 of the inverter circuit, and parasitic inductances generated on the power trace 31 and parasitic inductances generated on the positive dc bus 11 may be parallel when the inverter circuit works, so that total parasitic inductances generated by the inverter circuit may be reduced, and voltage spikes, power consumption and power interference devices may be reduced when the inverter is turned off may be reduced.

In addition, a welding area 151 may be disposed on the substrate 10, where the welding area 151 includes a plurality of power devices that are respectively in one-to-one correspondence with a first welding sub-area 1511, a second welding sub-area 1512, a third welding sub-area 1513, a fourth welding sub-area 1514, a fifth welding sub-area 1515, and a sixth welding sub-area 1516, and the multi-purpose power devices may be welded on the corresponding welding sub-areas in one-to-one correspondence to form an inverter circuit, so as to implement a frequency conversion function of the frequency converter.

Secondly, since the heat conducting layer 14 electrically connects the collector of the first power device, the collector of the third power device and the collector of the fifth power device in sequence, the first heat conducting area 141 can be arranged under the welding subareas corresponding to the first power device, the third power device and the fifth power device one by one respectively, and the first welding subarea 1511, the third welding subarea 1513 and the fifth welding subarea 1515 are all positioned in the first heat conducting area 141 along the thickness direction of the substrate 10, so that the first heat conducting area 141 can radiate heat of the first power device, the third power device and the fifth power device at the same time, the heat radiating area is increased, and the heat radiating effect of the discrete device group 20 is further improved; further, the heat conductive layer 14 corresponding to the second welding sub-region 1512, the fourth welding sub-region 1514 and the sixth welding sub-region 1516 may be provided with a second heat conductive region 142, a fourth heat conductive region 143 and a sixth heat conductive region 144, so as to improve the heat dissipation effect of the discrete device group 20; in short, the hollowed-out area is disposed on the surface layer 15, and the heat conducting layer 14 may be laminated with a portion of the solder resist area 152, so that a portion of the heat conducting layer 14 may be exposed outside the surface layer 15, and another portion may be laminated in the surface layer 15, thereby improving the heat dissipation area of the power device and the heat dissipation effect of the discrete device group 20 while ensuring the connection stability of the power device and the substrate 10.

Furthermore, the edge of the bonding region 151 may be provided with a flow guiding region 153, so that when the power device is bonded on the bonding region 151, the bonding material such as solder paste between the power device and the bonding region 151 may be extruded into the flow guiding region 153, thereby preventing the bonding material from flowing into the solder mask region 152, and causing short circuit of the circuit on the substrate 10.

The present utility model describes a discrete component and metal substrate 10 assembly with low parasitic inductance, low cost, high design flexibility, all employing conventional materials, which is exemplified by a three-phase inverter, applicable to variable frequency drives. The main innovation point is the design of the special metal substrate 10 and the discrete power device assembly and the protection design thereof; the core breakthrough point is that with the design flexibility, different topologies can be matched by using IGBT or MOSFET, and the method is applied to various products.

As shown in fig. 1 to 3, the PIM/IPM module can be equivalently replaced by an improved metal substrate 10 and discrete device assembly scheme according to the present utility model. The assembly includes a lowermost metal substrate 10 and six power components soldered on top, a thermistor 23, pins 22 and other aluminum substrate 10 related designs. Wherein, three power devices of upper bridge and three power devices of lower bridge are arranged back to back, effectively reduce the length of power wiring 31 on motherboard 30, reach the purpose of making compact converter.

The bottommost layer of the metal substrate 10 is made of metal, so that the effect of heat generated during the operation of the device is effectively conducted; the specific thickness of the middle insulating layer 13 can be 0.1-0.2 mm, and the insulation between the backboard (electrified) of the discrete device and the radiator is achieved; the uppermost part is a bonding pad with specific thickness of 60-100 microns, and has the functions of conducting electricity, fixing components and the like. The power device can be selected from different models of different manufacturers, and has high flexibility in general design and convenient replacement. The thermistor 23 adopts a low-temperature and high-temperature resistant negative temperature coefficient thermistor 23, and is packaged in 0603 or cylindrical package. The contact pin 22 is packaged in a special way, is convenient for the machine to be stuck, is welded on the upper part of the metal substrate 10, and keeps a safe creepage distance with the power device.

First, the power components select the most common TO247 packaged IGBTs. In the application of the system, the theoretical values of the conduction loss and the switching loss of each IGBT and the freewheeling diode of the three-phase inverter bridge are obtained through calculation, and then the steady-state total loss is obtained through addition.

P _{Tot(FWD+IGBT)} ＝P _{cond(FWD+IGBT)} +P _SW(FWD+IGBT)

The material of the metal substrate 10 is selected according to the total loss of 6 IGBTs of the inverter bridge and the heat dissipation capacity of the refrigerant heat radiator 40. The thickness of the metal base can be 1-3 mm by comprehensively pushing over and selecting the material with the thermal conductivity coefficient of the insulating layer 13 of nominal 3W/m.k. The main purpose of thickness selection of the substrate 10 is that after the IGBT single tube pins are bent, the pins do not need to be cut, and the substrate can be directly welded on the metal substrate 10 and just meets the structural design requirement of the frequency converter, and meanwhile, the heat dissipation effect is not excessively affected.

As shown in fig. 1, the surface of the metal substrate 10 has two groups of bonding pads, and four larger areas are designed for reflow soldering of the IGBT back plate. Q11 (first power device), Q13 (third power device), Q15 (fifth power device) are upper bridge IGBT, share a rectangular or polygonal bonding pad, top Solder layer (namely Solder resist area 152) opens six windows respectively, wherein three windows with large area are used for the back panel welding of three devices Q11 (first power device), Q13 (third power device), Q15 (fifth power device) respectively, and in addition, the window opening with smaller area is used for more effectively conducting heat around IGBT package to refrigerant radiator 40. The polygonal pad has both conductive and thermally conductive functions.

As the P end of the busbar of the frequency converter, the busbar is connected with the P line on the driving board in parallel, so that the parasitic inductance of the connecting line between the collecting electrodes of 3 IGBTs of the upper bridge is effectively reduced:

1/L＝1/L1+1/L2

therefore, the bus voltage rush-up phenomenon caused by parasitic inductance when the IGBT is turned off is inhibited to a certain extent, and the aim of reducing turn-off loss is fulfilled:

V＝L*di/dt

in another aspect, the co-spread land area is more conducive to rapid heat transfer to the system heat sink, thereby reducing device junction temperature:

Q＝△T/R＝△T·λ·S/L

wherein: r=l/(λ·s), Q: heat (w), Δt: temperature difference (k), R: thermal resistance (k/w), L: thickness (m), λ: thermal conductivity [ w/(m·k) ], S: area (square meter).

The design of a plurality of small rectangular windows in the middle of each IGBT enables the total thermal resistance of the upper part of the bonding pad to be smaller, and part of heat can be directly conducted into the air instead of being conducted into the air after passing through green oil, so that the heat dissipation capacity of the metal substrate 10 is effectively improved.

The horn-shaped window with the upper part of each window being placed towards the contact surface of the bonding pad is designed for guiding liquid tin, so that the problem that molten tin paste is extruded out of a solder mask layer due to extrusion between a chip and a metal substrate 10 in the reflow soldering process, and then is sprayed to the periphery of an IGBT device on the surface of the metal substrate 10 to form tin balls is effectively prevented. The design can effectively reduce the short circuit risk caused by tin balls, and indirectly improve the quality and service life of electronic products.

The three-phase inverter has three lower bridge IGBT numbers of Q12 (second power device), Q14 (fourth power device) and Q16 (sixth power device), and is provided with three independent large bonding pads, the design concept is the same as that of an upper bridge IGBT, and the three lower bridge IGBT numbers respectively comprise liquid tin diversion design for preventing tin bead injection, windowing design for improving heat dissipation effect and the like. The Q12 (second power device), Q14 (fourth power device) and Q16 (sixth power device) bonding pads are the collectors of the corresponding IGBTs, so that the three phases are output U, V, W by the inverter bridge respectively, the potentials of the three phases are different, and the creepage distance of more than 6.3 millimeters is required to be met in design. As can be seen from the above formula, the heat dissipation effect is proportional to the pad area, so that the pads as large as possible are designed on the surface of the limited metal substrate 10 to improve the heat dissipation capability of the system.

The seventh solder sub-area 1517 is composed of four pads of the same size, to which pins 22 for soldering the thermocouple signals are soldered. The two bonding pads are auxiliary bonding pads which are designed to enable the pin 22 to stand stably during reflow soldering, and no transmission signal is generated. The other two bonding pads are respectively connected with two ends of the negative temperature coefficient thermistor 23, and transmit an electric signal converted from a thermal signal of the thermocouple to the driving plate. The area of the pad window and the Top Paste layer (i.e., the bonding area 151) is about 2-3 times larger than the actual bonding area of the lower pin of the pin 22, so as to effectively increase the push-pull force of the pin 22. The line from the negative temperature coefficient thermistor 23 to the contact pin 22 is designed according to the shortest route principle, and the distance between the negative temperature coefficient thermistor and the board edge is required to be ensured to be more than 5 mm, so that the breakdown voltage to the ground is ensured to be more than 5 kV.

Two cylindrical through holes are formed in the diagonal line of the metal substrate 10, and serve as positioning holes of the protective support. The first design purpose is to prevent the metal substrate 10 from horizontal offset with the protective bracket during the assembly process, thereby improving the production efficiency; the second design purpose is to reduce the stress damage to IGBT pins caused by vibration in the horizontal direction of the whole machine to a certain extent when the system is in operation. The metal substrate 10 is fixed to the heat sink by four other vias, and the vias are kept at a distance of 5 mm or more from the pads, thereby ensuring a withstand voltage of 5kV or more.

The design of the arc edge of the metal substrate 10 aims to prevent the problem of short circuit caused by water drops accumulated at the upper part of the metal substrate and then left on the surface of the metal substrate.

In the description of the present utility model, it should be understood that the terms "length," "thickness," "upper," "lower," "front," "rear," "left," "right," "horizontal," "top," "bottom," "inner," "outer," and the like indicate or are based on the orientation or positional relationship shown in the drawings, merely to facilitate description of the present utility model and simplify description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present utility model.

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 utility model, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.

In the present utility model, unless explicitly specified 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 above terms in the present utility model can be understood by those of ordinary skill in the art according to the specific circumstances.

In the present utility model, 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.

In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present utility model. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.

While embodiments of the present utility model have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the utility model, and that variations, modifications, alternatives and variations may be made to the above embodiments by one of ordinary skill in the art within the scope of the utility model.

Claims (14)

1. A power device assembly, comprising:

a substrate (10);

-a discrete device group (20), the discrete device group (20) comprising power devices of an inverter circuit;

the power supply device comprises a motherboard (30), wherein a power wiring (31) is arranged on the motherboard (30), and the power wiring (31) is connected with a positive direct current bus (11) of the inverter circuit in parallel.

2. The power device assembly according to claim 1, wherein the substrate (10) comprises a bottom layer (12), an insulating layer (13), a heat conducting layer (14) and a surface layer (15), and the bottom layer (12), the insulating layer (13), the heat conducting layer (14) and the surface layer (15) are sequentially stacked in a thickness direction of the substrate (10), wherein the surface layer (15) comprises a soldering region (151) and a solder resist region (152).

3. The power device assembly according to claim 2, characterized in that the surface layer (15) is provided with a first hollowed-out area, the heat conducting layer (14) forms the welding area (151) on the surface opposite to the first hollowed-out area, the heat conducting layer (14) is partially overlapped with the welding-resisting area (152) in the projection of the thickness direction of the substrate (10).

4. A power device assembly according to claim 3, wherein the inverter circuit comprises an upper bridge circuit and a lower bridge circuit, the power devices of the inverter circuit are arranged on the welding area (151), and the first electrical connection parts (21 a) of the power devices in the upper bridge circuit and the second electrical connection parts (21 b) of the power devices in the lower bridge circuit are close to each other.

5. The power device assembly of claim 4, wherein the upper bridge circuit comprises a first power device, a third power device and a fifth power device, the thermally conductive layer (14) comprises a first thermally conductive region (141), and projections of welding regions (151) corresponding to the first power device, the third power device and the fifth power device in a thickness direction of the substrate (10) are all within the first thermally conductive region (141).

6. The power device assembly of claim 4, wherein the lower bridge circuit includes a second power device, a fourth power device, and a sixth power device, the thermally conductive layer (14) includes a second thermally conductive region (142), a fourth thermally conductive region (143), and a sixth thermally conductive region (144), the welding region (151) includes a second welding sub-region (1512) corresponding to the second power device, a fourth welding sub-region (1514) corresponding to the fourth power device, and a sixth welding sub-region (1516) corresponding to the sixth power device,

a projection of the second welding subarea (1512) in the thickness direction of the substrate (10) is positioned in the second heat conduction area (142), a projection of the fourth welding subarea (1514) in the thickness direction of the substrate (10) is positioned in the fourth heat conduction area (143), and a projection of the sixth welding subarea (1516) in the thickness direction of the substrate (10) is positioned in the sixth heat conduction area (144).

7. The power device assembly of claim 6, wherein a distance between the second (1512), fourth (1514) and sixth (1516) solder subregions in a width direction of the substrate is greater than a first preset distance.

8. A power device assembly according to claim 3, wherein the surface layer (15) is further provided with a second hollowed-out area, the second hollowed-out area is connected with the first hollowed-out area, the heat conducting layer (14) is provided with a diversion area (153) on a surface opposite to the second hollowed-out area, and the area of the diversion area (153) is smaller than the area of the welding area (151).

9. The power device assembly according to claim 2, wherein the discrete device group (20) further comprises a pin (22) and a thermistor (23), the soldering region (151) further comprises a plurality of seventh soldering subregions (1517), the pin (22) is disposed on the plurality of seventh soldering subregions (1517), and two ends of the thermistor (23) are respectively connected with any two of the seventh soldering subregions (1517).

10. The power device assembly according to claim 9, characterized in that the minimum distance of the thermistor (23) from the edge of the substrate (10) is larger than a second preset distance.

11. The power device assembly of any of claims 2-10, further comprising:

and the refrigerant radiator (40) is connected with the bottom surface layer (12) and arranged below the bottom surface layer (12), and the projection of the bottom surface layer (12) in the thickness direction of the substrate (10) is positioned in the refrigerant radiator (40).

12. The power device assembly according to claim 11, characterized in that the substrate (10) is configured as an arc on the side edge opposite to the direction of gravity.

13. The power device assembly according to any of claims 2-10, wherein the thickness of the insulating layer (13) is 0.1-0.2 mm and the thickness of the soldering region (151) is 60-100 μm.

14. A frequency converter, characterized in that it comprises a power device assembly according to any of claims 1-13.