Power module structure with adjustable parasitic inductance

Abstract

The present invention discloses a power module structure with adjustable parasitic inductance. In this structure, the DBC substrate includes a first copper plate and a second copper plate disposed on both sides of the insulating layer. The first copper plate is divided into an upper bridge region and a lower bridge region at intervals. The upper bridge power device and the lower bridge power device are respectively disposed in the upper bridge region and the lower bridge region, and the terminals of the upper bridge power device are connected to the lower bridge region, and the terminals of the lower bridge power device are connected to the second copper plate. Both ends of the smoothing capacitor are respectively connected to the upper bridge region and the second copper plate. There are at least two internal capacitors which are respectively located on both sides of the upper bridge region, and both ends of the internal capacitors are respectively connected to the upper bridge region and the second copper plate. Both ends of the smoothing capacitor form the input terminals of the power module, and the lower bridge region forms the motor connection phase terminals. This structure reduces the parasitic inductance of the power module itself by adjusting the positions and parameters of the electrical components inside the power module package, avoids damage to the power devices caused by surge voltage, and thus improves the performance of the motor controller in controlling the motor.

Description

Technical Field

[0001] The present invention relates to the field of power electronics technology, and in particular, to a power module structure with adjustable parasitic inductance. Background Art

[0002] The battery, motor controller, and motor of new energy vehicles constitute the "three electrics" system of new energy vehicles. Among them, the motor controller plays a key role in energy conversion, motor torque control, and speed control. Currently, power devices represented by IGBTs are the core components of the motor controller, determining key performance such as the power density of the motor controller and accounting for a large proportion of the cost of the motor controller.

[0003] With the increasing requirements of new energy vehicles for high power density, high efficiency, and high reliability of motor controllers, in recent years, the application trend of silicon carbide devices in new energy vehicles has become increasingly obvious. International well-known vehicle manufacturers and component giants are all carrying out the application and testing of SiC devices in new energy vehicles.

[0004] The switching process of power devices such as IGBTs and SiC is sensitive to the parasitic inductance of the power module itself. Larger parasitic inductance brings higher switching voltage spikes. Therefore, if a conventional power module packaging structure is used, the parasitic inductance of the power module itself is relatively high, which is extremely disadvantageous for the application of the power module.

[0005] In the three-phase AC motor drive system of new energy vehicles, the motor controller uses a high-frequency carrier to drive the power device for high-speed on-off control. The surge voltage proportional to the magnitude of the parasitic inductance of the drive main circuit will be applied to the power device. When the surge voltage is too large, it may cause the power device to be broken down and damaged. Therefore, reducing the parasitic inductance of the drive main circuit is an important research topic. As Figure 1 shown, the parasitic inductance of the inverter circuit of the motor controller mainly includes the parasitic inductance L1 of the current loop near the power device 1, the parasitic inductance L2 of the connection terminal part of the smoothing capacitor C f and the power device 1 circuit, and the parasitic inductance L3 of the smoothing capacitor C f busbar.

[0006] Figure 1 In the three-phase AC motor drive system shown, on the premise that the current change rate remains constant, the relationship between the surge voltage V1 and the parasitic inductance is shown in Equation 1,

[0007]

[0008] where, is the current change rate; it can be seen from Equation 1 that the surge voltage increases with the increase of the sum of the parasitic inductance L1, parasitic inductance L2, and parasitic inductance L3. Therefore, how to reduce the internal parasitic inductance of the power module is the key factor to improve the performance of the motor controller. Summary of the Invention

[0009] The technical problem to be solved by the present invention is to provide a power module structure with adjustable parasitic inductance. By adjusting the positions and parameters of electrical components inside the power module package, the parasitic inductance of the power module itself is reduced, and the damage to power devices caused by surge voltage formed by parasitic inductance is avoided, thereby improving the performance of the motor controller in controlling the motor.

[0010] To solve the above technical problem, the power module structure with adjustable parasitic inductance of the present invention includes a DBC substrate of the power module, smoothing capacitors, upper-bridge power devices and lower-bridge power devices, and also includes internal capacitors. The DBC substrate includes a first copper plate and a second copper plate provided on both sides of an insulating layer. The first copper plate is divided into an upper-bridge area and a lower-bridge area at intervals. The upper-bridge power devices and the lower-bridge power devices are respectively arranged in the upper-bridge area and the lower-bridge area, and the terminals of the upper-bridge power devices are connected to the lower-bridge area, and the terminals of the lower-bridge power devices are connected to the second copper plate. Both ends of the smoothing capacitor are respectively connected to the upper-bridge area and the second copper plate. There are at least two internal capacitors and they are respectively located on both sides of the upper-bridge area. Both ends of the internal capacitor are respectively connected to the upper-bridge area and the second copper plate. Both ends of the smoothing capacitor form the input terminals of the power module, and the lower-bridge area forms the motor connection phase terminals.

[0011] Further, the area of the second copper plate is larger than that of the first copper plate, and the four sides of the second copper plate protrude from the four sides of the first copper plate. The terminals of the lower-bridge power devices are connected to the protruding part of the second copper plate by bonding wires, and the internal capacitors are located in the upper-bridge area and are connected to the protruding part of the second copper plate by bonding wires.

[0012] Further, the lower-bridge area is divided into a first lower-bridge area and a second lower-bridge area arranged at intervals left and right. The lower part of the upper-bridge area extends between the first lower-bridge area and the second lower-bridge area, and the lower-bridge power devices are evenly distributed in the first lower-bridge area and the second lower-bridge area.

[0013] Further, the upper-bridge area is divided into a first upper-bridge area and a second upper-bridge area arranged at intervals up and down. The second upper-bridge area is located between the first lower-bridge area and the second lower-bridge area. The upper-bridge power devices are located in the second upper-bridge area and are connected to the first upper-bridge area by bonding wires. Both ends of the internal capacitor are respectively connected to the first upper-bridge area and the second copper plate.

[0014] Further, an internal capacitor is connected between the second upper-bridge area and the second copper plate.

[0015] Further, each phase of the upper-bridge power devices and the lower-bridge power devices has at least two and is arranged in parallel in the vertical direction between the input terminals of the power module and the motor connection phase terminals.

[0016] Further, the current path connecting the lower-bridge power device and the smoothing capacitor is divided into a first current path and a second current path, and the two current paths sandwich the parallel-connected upper-bridge power devices from both sides.

[0017] Further, the upper-bridge power device and the lower-bridge power device are respectively an IGBT tube or a MOSFET tube.

[0018] Further, the capacitance value of the internal capacitor is less than 1 / 10 of the capacitance value of the smoothing capacitor.

[0019] Further, the internal capacitor is a resistor-capacitor device.

[0020] Since the power module structure with adjustable parasitic inductance of the present invention adopts the above technical solution, that is, in this structure, the DBC substrate includes a first copper plate and a second copper plate disposed on both sides of the insulating layer. The first copper plate is divided into an upper-bridge area and a lower-bridge area at intervals. The upper-bridge power device and the lower-bridge power device are respectively disposed in the upper-bridge area and the lower-bridge area, and the terminals of the upper-bridge power device are connected to the lower-bridge area, and the terminals of the lower-bridge power device are connected to the second copper plate. Both ends of the smoothing capacitor are respectively connected to the upper-bridge area and the second copper plate. There are at least two internal capacitors and they are respectively located on both sides of the upper-bridge area. Both ends of the internal capacitor are respectively connected to the upper-bridge area and the second copper plate. Both ends of the smoothing capacitor form the input terminals of the power module, and the lower-bridge area forms the motor connection phase terminals. By adjusting the positions and parameters of the electrical components inside the power module package, this structure reduces the parasitic inductance of the power module itself, avoids damage to the power device caused by the surge voltage formed by the parasitic inductance, and thus improves the performance of the motor controller in controlling the motor. Description of the Drawings

[0021] The following further describes the present invention in detail with reference to the drawings and embodiments:

[0022] Figure 1 It is a schematic diagram of the parasitic inductance distribution of the inverter loop of the motor controller;

[0023] Figure 2 It is a schematic diagram of the power module structure with adjustable parasitic inductance of the present invention;

[0024] Figure 3 It is a schematic diagram of the connection of the lower-bridge power device and the internal capacitor sub in this power module using bonding wires;

[0025] Figure 4 It is a schematic diagram of the division of the lower-bridge area of this power module;

[0026] Figure 5 It is a schematic diagram of the division of the upper-bridge area of this power module;

[0027] Figure 6This is a schematic diagram of the current path between the lower - bridge power device and the smoothing capacitor in this power module;

[0028] Figure 7 This is a schematic diagram of the principle of the inverter circuit of the motor controller applying this power module. Specific embodiments

[0029] For example Figure 2 As shown, the power - module structure with adjustable parasitic inductance of the present invention includes the DBC substrate 2 of the power module, the smoothing capacitor C f and the upper - bridge power device 11 and the lower - bridge power device 12, and also includes the internal capacitor C z , the DBC substrate 2 includes a first copper plate 21 and a second copper plate 22 disposed on both sides of the insulating layer. The first copper plate 21 is divided into an upper - bridge area 211 and a lower - bridge area 212 at intervals. The upper - bridge power device 11 and the lower - bridge power device 12 are respectively disposed in the upper - bridge area 211 and the lower - bridge area 212, and the terminals of the upper - bridge power device 11 are connected to the lower - bridge area 212, and the terminals of the lower - bridge power device 12 are connected to the second copper plate 22. The two ends of the smoothing capacitor C f are respectively connected to the upper - bridge area 211 and the second copper plate 22. The internal capacitor C z is at least two and is respectively located on both sides of the upper - bridge area 211. The two ends of the internal capacitor C z are respectively connected to the upper - bridge area 211 and the second copper plate 22. The two ends of the smoothing capacitor C f constitute the input terminals 5 of the power module, and the lower - bridge area 212 constitutes the motor - connection phase terminals 6.

[0030] For example Figure 3 As shown, preferably, the area of the second copper plate 22 is larger than that of the first copper plate 21, and the periphery of the second copper plate 22 protrudes from the periphery of the first copper plate 21. The terminals of the lower - bridge power device 12 and the protruding part of the second copper plate 22 are connected by a bonding wire 7. The internal capacitor C z is located in the upper - bridge area 211 and is connected to the protruding part of the second copper plate 22 by a bonding wire 8.

[0031] For example Figure 4 As shown, preferably, the lower - bridge area 212 is divided into a first lower - bridge area 212A and a second lower - bridge area 212B arranged at intervals left and right. The lower part of the upper - bridge area 211 extends between the first lower - bridge area 212A and the second lower - bridge area 212B, and the lower - bridge power devices 12 are evenly distributed in the first lower - bridge area 212A and the second lower - bridge area 212B. <{

[0032] For example Figure 5As shown, preferably, the upper bridge region 211 is divided into a first upper bridge region 211A and a second upper bridge region 211B which are arranged at intervals up and down. The second upper bridge region 211B is located between the first lower bridge region 212A and the second lower bridge region 212B. The upper bridge power device 11 is located in the second upper bridge region 211B and is connected to the first upper bridge region 211A by a bonding wire 9. The internal capacitor C z has two ends respectively connected to the first upper bridge region 211A and the second copper plate 22.

[0033] Preferably, an internal capacitor C z is connected between the second upper bridge region 211B and the second copper plate 22.

[0034] Preferably, each phase of the upper bridge power device 11 and the lower bridge power device 12 has at least two, and they are arranged in parallel in the vertical direction between the power module input terminal 5 and the motor connection phase terminal 6.

[0035] As Figure 6 shown, preferably, the current path through which the lower bridge power device 12 is connected to the smoothing capacitor C f is divided into a first current path 3 and a second current path 4, and the two current paths sandwich the upper bridge power device 11 connected in parallel from both sides.

[0036] Preferably, the upper bridge power device 11 and the lower bridge power device 12 are respectively IGBT tubes or MOSFET tubes.

[0037] Preferably, the capacitance value of the internal capacitor C z is less than 1 / 10 of the capacitance value of the smoothing capacitor C f .

[0038] Preferably, the internal capacitor C z is a resistor-capacitor device.

[0039] As Figure 7 shown, after applying this power module in the inverter loop of the motor controller, since an internal capacitor Cz is added in the inverter loop, the surge voltage V2 and the surge voltage V3 are expressed by Equation 2 and Equation 3,

[0040]

[0041]

[0042] Among them, L zLz is the parasitic inductance of the internal capacitor Cz, V2 is the surge voltage when the internal capacitor is added. Since the commutation loop is changed, the total parasitic inductance becomes L1 + Lz, and V3 is the surge voltage brought about by the resonance of L2, L3, and Cz. According to Equation 2, the magnitude of V2 is mainly affected by the parasitic inductance Lz and the inductance L1 of the current circuit near the power device. Therefore, compared with Equation 1, there are fewer factors affecting the parasitic inductance, and it is easier to control and reduce the surge voltage. According to Equation 3, the magnitude of V3 is mainly affected by the inductance L3 of the smoothing capacitor busbar, the inductance L2 of the connection terminal part between the smoothing capacitor and the power device circuit, and the magnitude of the internal capacitor Cz. Among them, the capacitance value of the internal capacitor can be adjusted, and the magnitude of V3 can be easily suppressed.

[0043] Therefore, through the setting of the internal capacitor and the adjustment of parameters, it is theoretically possible to effectively reduce the surge voltage applied to the power device. However, the parasitic inductance Lz of the internal capacitor is generally not small. Through the layout of the electrical components in this power module, the influence of the parasitic inductance Lz of the internal capacitor on the surge voltage can be effectively reduced.

[0044] This power module reduces the parasitic inductance Lz of the internal capacitor by using a current magnetic field to cancel it, thereby reducing the surge voltage V2 applied to the power device. The DBC substrate of the power module adopts a two-layer copper plate structure. Generally, the current directions of the first copper plate and the second copper plate are opposite, thereby reducing the parasitic inductance. At the same time, the area of the second copper plate is larger than that of the first copper plate. Since the current needs to pass through the terminals connecting the smoothing capacitor C f and the power device circuit, the current converges from all directions near the copper plate towards the terminal part and flows towards the terminal, that is, there are current components in the X direction and the Y direction. Therefore, the additional internal capacitor is arranged on the first copper plate, and the parasitic inductance of the internal capacitor is reduced by the cancellation of the current components of the second copper plate. Since there must be current components in the X direction and the Y direction in the current of the second copper plate, the internal capacitor Cz arranged on the first copper plate can be in any direction.

[0045] The condition for reducing the parasitic inductance Lz of the internal capacitor arranged on the first copper plate is that current components in the X direction and the Y direction need to be generated on the second copper plate. Therefore, this power module arranges the internal capacitor Cz near the terminal connecting the smoothing capacitor because the current needs to converge from all directions of the copper plate towards the terminal, thereby generating current components in the X direction and the Y direction. In addition, the current of the first copper plate is connected to the outer periphery of the second copper plate through a bonding wire, and the current density at the center of the second copper plate will be smaller, causing the current to converge towards the terminal direction connecting the smoothing capacitor, generating current components in the X direction and the Y direction.

[0046] The power device is described by taking the MOSFET transistor as an example. The three terminals of the MOSFET transistor are the gate, the drain, and the source. Inside the power module, the upper bridge area of the first copper plate is connected to the positive electrode of the smoothing capacitor, and the second copper plate is connected to the negative electrode of the smoothing capacitor. An internal capacitor Cz for reducing the surge voltage is arranged between the positive terminal and the negative terminal connected to the positive and negative electrodes of the smoothing capacitor. By adjusting the parameters and the arrangement position of the internal capacitor, the area of the commutation loop during the switching commutation process of the power device is reduced, thereby reducing the parasitic inductance.

[0047] The upper bridge area of the first copper plate is connected to the positive electrode of the smoothing capacitor. The source electrode of the upper bridge MOSFET transistor located in the upper bridge area of the first copper plate is connected to the upper bridge area by welding. The drain electrode of the upper bridge MOSFET transistor is connected to the lower bridge area of the first copper plate through a bonding wire, so as to be connected to the source electrode of the lower bridge MOSFET transistor; the source electrode of the lower bridge MOSFET transistor is connected to the lower bridge area by welding, and the drain electrode of the lower bridge MOSFET transistor is connected to the second copper plate through a bonding wire; the second copper plate is connected to the negative electrode of the smoothing capacitor. At least two internal capacitors Cz are configured in each phase of the control loop to achieve clamping and paralleling the power devices from both sides. The internal capacitor Cz can be connected across the first copper plate and the second copper plate, or the internal capacitor Cz can be arranged on the first copper plate and connected to the second copper plate by a bonding wire, improving the flexibility of the packaging of the internal capacitor Cz.

Claims

1. A power module structure with adjustable parasitic inductance, comprising a DBC substrate of the power module, a smoothing capacitor, an upper-bridge power device, and a lower-bridge power device, characterized in that: It further includes a first internal capacitor, a second internal capacitor and a third internal capacitor. The DBC substrate includes a first copper plate and a second copper plate disposed on both sides of the insulating layer, and the current directions of the first copper plate and the second copper plate are opposite. The first copper plate is divided into an upper bridge area and a lower bridge area at intervals. The upper bridge power device and the lower bridge power device are respectively disposed in the upper bridge area and the lower bridge area, and the terminals of the upper bridge power device are connected to the lower bridge area, and the terminals of the lower bridge power device are connected to the second copper plate. Both ends of the smoothing capacitor are respectively connected to the upper bridge area and the second copper plate. The first internal capacitor and the second internal capacitor are respectively located on both sides of the upper bridge area and near the terminals connecting the smoothing capacitor. Both ends of the smoothing capacitor form power module input terminals; Wherein, the lower bridge area is divided into a first lower bridge area and a second lower bridge area arranged at intervals left and right. The lower part of the upper bridge area extends between the first lower bridge area and the second lower bridge area. The lower bridge power devices are evenly distributed in the first lower bridge area and the second lower bridge area; The upper bridge area is divided into a first upper bridge area and a second upper bridge area arranged at intervals up and down. The second upper bridge area is located between the first lower bridge area and the second lower bridge area. The upper bridge power device is located in the second upper bridge area and is connected to the first upper bridge area by a bonding wire. Both ends of the first internal capacitor and the second internal capacitor are respectively connected to the first upper bridge area and the second copper plate; A third internal capacitor is connected between the second upper bridge area and the second copper plate.

2. The power module structure with adjustable parasitic inductance according to claim 1, characterized in that: The area of the second copper plate is larger than that of the first copper plate, and the four sides of the second copper plate protrude from the four sides of the first copper plate. The terminals of the lower bridge power device and the protruding part of the second copper plate are connected by a bonding wire. The first internal capacitor, the second internal capacitor and the third internal capacitor are connected to the protruding part of the second copper plate by a bonding wire.

3. The power module structure with adjustable parasitic inductance according to claim 1, characterized in that: Each phase of the upper bridge power device and the lower bridge power device has at least two, and they are arranged in parallel in the vertical direction between the power module input terminal and the motor connection phase terminal.

4. The power module structure with adjustable parasitic inductance according to claim 1, wherein: The current path through which the lower bridge power device is connected to the smoothing capacitor is divided into a first current path and a second current path, and the two current paths sandwich the parallel upper bridge power device from both sides.

5. The power module structure with adjustable parasitic inductance according to claim 1, wherein: The upper bridge power device and the lower bridge power device are respectively an IGBT tube or a MOSFET tube.

6. The power module structure with adjustable parasitic inductance according to claim 1, wherein: The capacitance values of the first internal capacitor, the second internal capacitor and the third internal capacitor are less than 1 / 10 of the capacitance value of the smoothing capacitor.

7. The power module structure with adjustable parasitic inductance according to claim 1, characterized in that: The first internal capacitor, the second internal capacitor and the third internal capacitor are capacitor components.

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