LOW STRAY INDUCTANCE BUSBAR STRUCTURE FOR POWER MODULE

Abstract

A busbar structure with less stray inductance for a power module includes a radiator, a copper-clad ceramic substrate, a wafer, a plastic case, a positive busbar, a negative busbar and a potting compound. The copper-clad ceramic substrate is welded on the radiator. The wafer is welded on the copper-clad ceramic substrate. The plastic case is fixed on the radiator. The positive and negative busbars are packaged in the plastic case, and fixed on the copper-clad ceramic substrate by ultrasonic bonding. An electrical clearance between wafers as well as an electrical clearance between the positive and negative busbars are ensured by potting. A part of the positive busbar covers a part of the negative busbar. The part of the positive busbar and the part of the negative busbar extend from the inside of the plastic case to the outside of the plastic case.

Claims

1. A busbar structure with less stray inductance for a power module, comprising: a radiator; a copper-clad ceramic substrate; a wafer; a plastic case; a positive busbar; a negative busbar; and potting compound; wherein the copper-clad ceramic substrate is welded on the radiator, the wafer is welded on the copper-clad ceramic substrate, the plastic case is fixed on the radiator, the positive busbar and the negative busbar are packaged in the plastic case with the potting compound, and are fixed on the copper-clad ceramic substrate by ultrasonic bonding, to form an electrical circuit of the power module, an electrical clearance between wafers as well as an electrical clearance between the positive busbar and the negative busbar are ensured by potting with the potting compound, and wherein a part of the positive busbar covers a part of the negative busbar, and the part of the positive busbar and the part of the negative busbar extend from the inside of the plastic case to the outside of the plastic case.

2. The busbar structure with less stray inductance for a power module according to claim 1, wherein the part of the positive busbar and the part of the negative busbar that covers each other, extending out of the plastic case, is larger than or equal to 0 in length.

3. The busbar structure with less stray inductance for a power module according to claim 1, the positive busbar is parallel with and overlap the negative busbar, the positive busbar and the negative busbar extend to the copper-clad ceramic substrate, the positive busbar is arranged above the negative busbar or the negative busbar is arranged above the positive busbar, and a distance between the positive busbar and the negative busbar is less than or equal to 3 mm.

4. The busbar structure with less stray inductance for a power module according to claim 3, wherein a difference between a width and a length of the part of the positive busbar that covers the part of the negative busbar is larger than or equal to 0.

5. The busbar structure with less stray inductance for a power module according to claim 3, wherein a potting surface of the potting compound is higher than at least a lower one of the positive busbar and the negative busbar that overlap each other.

6. The busbar structure with less stray inductance for a power module according to claim 3, wherein the potting compound is silica gel or epoxy resin.

7. The busbar structure with less stray inductance for a power module according to claim 2, the positive busbar is parallel with and overlap the negative busbar, the positive busbar and the negative busbar extend to the copper-clad ceramic substrate, the positive busbar is arranged above the negative busbar or the negative busbar is arranged above the positive busbar, and a distance between the positive busbar and the negative busbar is less than or equal to 3 mm.

8. The busbar structure with less stray inductance for a power module according to claim 7, wherein a difference between a width and a length of the part of the positive busbar that covers the part of the negative busbar is larger than or equal to 0.

9. The busbar structure with less stray inductance for a power module according to claim 7, wherein a potting surface of the potting compound is higher than at least a lower one of the positive busbar and the negative busbar that overlap each other.

10. The busbar structure with less stray inductance for a power module according to claim 7, wherein the potting compound is silica gel or epoxy resin.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present disclosure is further described in detail in conjunction with the accompanying drawings and embodiments below. In the drawings:

[0017] FIG. 1 is a schematic structural diagram illustrating a main circuit for driving a three-phase alternating current motor;

[0018] FIG. 2 illustrates the main circuit in the A-A direction as shown in FIG. 1;

[0019] FIG. 3 is a schematic diagram illustrating a busbar structure with less stray inductance for a power module according to the present disclosure;

[0020] FIG. 4 is a schematic diagram illustrating the busbar structure in which a negative busbar is arranged above a positive busbar and the negative busbar overlaps the positive busbar;

[0021] FIG. 5 is a schematic axonometric view partially illustrating the busbar structure;

[0022] FIG. 6 is a schematic plane view partially illustrating the busbar structure;

[0023] FIG. 7 is a schematic diagram illustrating the busbar structure in which the positive busbar is arranged above the negative busbar and the positive busbar overlaps the negative busbar; and

[0024] FIG. 8 is a schematic diagram illustrating the busbar structure in which the negative busbar is arranged above the positive busbar and the negative busbar overlaps the positive busbar.

DETAILED DESCRIPTION

[0025] As shown in FIG. 3, a busbar structure with less stray inductance for a power module according to the present disclosure includes a radiator 4, a copper-clad ceramic substrate 5, a wafer 6, a plastic case 3, a positive busbar 1, a negative busbar 2 and a potting compound 7. The copper-clad ceramic substrate 5 is welded on the radiator 4. The wafer 6 is welded on the copper-clad ceramic substrate 5. The plastic case 3 is fixed on the radiator 4. The positive busbar 1 and the negative busbar 2 are packaged in the plastic case 3 with the potting compound 7. The positive busbar 1 and the negative busbar 2 are fixed on the copper-clad ceramic substrate 5 by ultrasonic bonding and form an electrical circuit of the power module. An electrical clearance between wafers 6 as well as an electrical clearance the positive and negative busbars 1 and 2 are ensured by potting with the potting compound 7. A part of the positive busbar 1 covers a part of the negative busbar 2. The part of the positive busbar 1 and the part of the negative busbar 2 extend from the inside of the plastic case 3 to the outside of the plastic case 3.

[0026] Preferably, as shown in FIGS. 3, 4, 5 and 6, the part of the positive busbar 1 and the part of the negative busbar 2 extend out of the plastic case 3 larger than or equal to 0 in length. That is, L4 in the drawings is greater than or equal to 0.

[0027] Preferably, as shown in FIGS. 3, 4, 7 and 8, the positive busbar 1 and the negative busbar 2 are arranged in parallel and overlap each other, and extend to the copper-clad ceramic substrate 5. The positive busbar 1 is arranged above the negative busbar 2. Alternatively, the negative busbar 2 is arranged above the positive busbar 1. A distance between the positive busbar 1 and the negative busbar 2 is less than or equal to 3 mm.

[0028] Preferably, a difference between a width and a length of the part of the positive busbar 1 that covers the part of the negative busbar 2 is larger than or equal to 0. Preferably, the width is equal to the length.

[0029] Preferably, a potting surface of the potting compound 7 is higher than at least a lower one of the positive busbar 1 and the negative busbar 2 that overlap each other.

[0030] Preferably, the potting compound 7 is silica gel or epoxy resin.

[0031] This structure effectively solves the problem of excessive stray inductance of a busbar terminal inside the power module. The positive busbar overlaps the negative busbar in the L2 area. The positive busbar and the negative busbar extend out of the plastic case to the inside of the power module. In addition, the electrical clearance between the positive and negative busbars as well as an electrical clearance between power modules are ensured by insulation potting with the potting compound, significantly reducing a part of the positive busbar not covering the negative busbar and a part of the negative busbar not covering the positive busbar. Therefore, the area S of the loop through which the current flows decreases, that is, the value of a×h in Equation (2) decreases. According to Equation (2), the stray inductance L decreases accordingly, thereby effectively reducing the surge voltage, avoiding the risk of breakdown of the power module, ensuring the switching characteristics of the power module, and improving the reliability of motor control.