Main circuit layout structure of a three-phase AC motor drive system controller

Abstract

The present invention discloses a main circuit layout structure of a controller for a three-phase AC motor drive system. This structure includes a power module with positive and negative busbars and a support capacitor with positive and negative busbars. The positive and negative busbars of the power module and the positive and negative busbars of the support capacitor are respectively connected by welding to form an inverter main circuit. After the positive and negative busbars of the power module horizontally extend to the outside of the power module body along the installation plane, they are bent by 180° and extended above the power module body. The positive and negative busbars of the support capacitor horizontally extend to the surfaces of the positive and negative busbars of the power module and are attached. The attachment part is connected by welding, so that the current directions of the positive and negative busbars of the power module and the positive and negative busbars of the support capacitor are opposite at the connection part, and at this time, the area of the loop through which the current flows is the smallest. This structure effectively reduces the surge voltage caused by stray inductance, avoids the risk of the power module being broken down, ensures the switching characteristics of the power module, and improves the reliability of motor drive control.

Description

Technical Field

[0001] The present invention relates to the technical field of motor control, and particularly to a main circuit layout structure of a controller for a three-phase AC motor drive system. Background Art

[0002] In a three-phase AC motor drive system, a high-frequency carrier is used to drive the power module to open and close at high speed, and a surge voltage proportional to the stray inductance of the drive main circuit is applied to the power module. The calculation of the surge voltage V1 is as shown in Equation (1):

[0003]

[0004] Wherein,

[0005] Then

[0006] In the formula: L is the stray inductance, φ is the magnetic flux, I is the current, B is the magnetic induction intensity, a is the length of the main circuit connection terminal busbar, w is the width of the main circuit connection terminal busbar, h is the spacing of the laminated busbar, and μ0 is the magnetic permeability of vacuum.

[0007] It can be seen that minimizing the stray inductance to the greatest extent can reduce the surge voltage V1. When the surge voltage V1 is too large, it may cause the power module to be broken down and damaged. Therefore, how to reduce the stray inductance of the drive main circuit is an important research topic.

[0008] Such as Figure 1 and Figure 2 shown, generally, the main circuit of the controller is composed of a power module and a support capacitor. Among them, the power module and the support capacitor are connected together by bolts through a busbar. As Figure 1 shown, one side of the busbar 4 of the power module 1 is connected to the copper layer of the insulating substrate 3, and the other side is connected to the busbar 5 of the support capacitor 2 through bolts 6 and inserts 7; as Figure 2 shown, the busbar 4 of the power module 1 and the busbar 5 of the support capacitor 2 are crimped together by a crimping tool 8 and a crimping tool 9, and then the busbar 4 of the power module 1 and the busbar 5 of the support capacitor 2 are connected together by welding 10.

[0009] Among them, as Figure 1 or Figure 2 shown, the spacing A is the length of the busbar at the bolt connection or welding connection part. The spacing A mainly considers the space required for bolt connection or welding, as well as the use and installation space of tools and tooling; the spacing B is the length between the terminal part from the insulating substrate 3 to the connection busbar 4 inside the power module. Usually, the range of the spacing B is encapsulated with resin;

[0010] Among them, the current loops in the regions of spacing A and spacing B can be regarded as forming current loops with the ground. At this time, the loop area S through which the current flows is relatively large, that is, a×h in Equation 2 is relatively large. According to Equation 2, the inductance L will increase accordingly.

[0011] In the main circuit, due to the stray inductance in the regions of spacing A and spacing B, the switching characteristics of the power module are seriously affected, reducing the reliability of the motor drive control. Summary of the Invention

[0012] The technical problem to be solved by the present invention is to provide a main circuit layout structure of a controller for a three-phase AC motor drive system. This structure effectively reduces the surge voltage caused by stray inductance, avoids the risk of breakdown of the power module, ensures the switching characteristics of the power module, and improves the reliability of the motor drive control.

[0013] To solve the above technical problem, the main circuit layout structure of the controller for the three-phase AC motor drive system of the present invention includes a power module with positive and negative busbars and a support capacitor with positive and negative busbars. Among them, the positive and negative busbars of the power module and the positive and negative busbars of the support capacitor are respectively connected by welding to form an inverter main circuit; after the positive and negative busbars of the power module horizontally extend to the outside of the power module body along the installation plane, they are bent 180° and extended above the power module body. The positive and negative busbars of the support capacitor horizontally extend to the surfaces of the positive and negative busbars of the power module and fit together. The fitting parts of the positive and negative busbars of the support capacitor and the positive and negative busbars of the power module are connected by welding, so that the current directions of the positive and negative busbars of the power module and the positive and negative busbars of the support capacitor are opposite at the connection parts. At this time, the area of the loop through which the current flows is the smallest.

[0014] Further, the positive and negative busbars of the power module are bent to form at least a parallel plane that fits with the positive and negative busbars of the support capacitor.

[0015] Further, the positive and negative busbars of the power module are bent to form a first horizontal plane, a vertical plane, and a second horizontal plane in sequence. The positive and negative busbars of the support capacitor are bent horizontally and vertically to fit with the second horizontal plane of the positive and negative busbars of the power module and are connected in parallel by welding.

[0016] Further, the second horizontal plane of the positive and negative busbars of the power module forms an opposite current direction with the first horizontal plane. At this time, the area of the loop through which the current flows is the smallest. The second horizontal plane of the positive and negative busbars of the power module forms an opposite current direction with the horizontal plane of the positive and negative busbars of the support capacitor. At this time, the area of the loop through which the current flows is the smallest. The vertical plane of the positive and negative busbars of the power module forms an opposite current direction with the vertical plane of the positive and negative busbars of the support capacitor. At this time, the area of the loop through which the current flows is the smallest.

[0017] Further, the distance between the first horizontal plane and the second horizontal plane of the positive and negative busbars of the power module is as small as possible, and the distance between the vertical planes of the positive and negative busbars of the power module and the vertical planes of the positive and negative busbars of the support capacitor is as small as possible. At this time, the area of the loop through which the current flows is the smallest.

[0018] Further, the height between the positive and negative busbars extending from the side of the power module body and the positive and negative busbars extending from the side of the support capacitor is as small as possible or flush.

[0019] Further, the welding method for the positive and negative busbars of the support capacitor to fit with the second horizontal plane of the positive and negative busbars of the power module is laser welding.

[0020] Since the main circuit layout structure of the three-phase AC motor drive system controller of the present invention adopts the above technical solution, that is, this structure includes a power module with positive and negative busbars and a support capacitor with positive and negative busbars. Among them, the positive and negative busbars of the power module and the positive and negative busbars of the support capacitor are respectively connected by welding to form an inverter main circuit; after the positive and negative busbars of the power module horizontally extend to the outside of the power module body along the installation plane, they are bent 180° and extended above the power module body. The positive and negative busbars of the support capacitor horizontally extend to the surface of the positive and negative busbars of the power module and fit together, and the fitting part is connected by welding, so that the current directions of the positive and negative busbars of the power module and the positive and negative busbars of the support capacitor are opposite at the connection part. At this time, the area of the loop through which the current flows is the smallest. This structure effectively reduces the surge voltage caused by stray inductance, avoids the risk of the power module being broken down, ensures the switching characteristics of the power module, and improves the reliability of motor drive control. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0022] Figure 1 FIG. is a schematic diagram of the main circuit layout of a traditional controller using bolt connection;

[0023] Figure 2 FIG. is a schematic diagram of the main circuit layout of a traditional controller using a welding connection method;

[0024] Figure 3 FIG. is a schematic diagram of the main circuit layout structure of the three-phase AC motor drive system controller of the present invention;

[0025] Figure 4 FIG. is a bending schematic diagram of the positive and negative busbars of the power module and the positive and negative busbars of the support capacitor in this structure. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] Embodiment example Figure 3As shown in the figure, the main circuit layout structure of the controller of the three-phase AC motor drive system of the present invention includes a power module 1 with positive and negative busbars 4 and a support capacitor 2 with positive and negative busbars 5. The positive and negative busbars 4 of the power module 1 and the positive and negative busbars 5 of the support capacitor 2 are respectively connected by welding to form an inverter main circuit. After the positive and negative busbars 4 of the power module 1 horizontally extend along the installation plane to the outside of the power module 1 body, they are bent by 180° and extended above the power module 1 body. The positive and negative busbars 5 of the support capacitor 2 horizontally extend along the installation plane to the surface of the positive and negative busbars 4 of the power module 1 and fit together. The fitting part of the positive and negative busbars 5 of the support capacitor 2 and the positive and negative busbars 4 of the power module 1 is connected by welding 10, so that the current directions of the positive and negative busbars 4 of the power module 1 and the positive and negative busbars 5 of the support capacitor 2 are opposite at the connection part, and at this time, the area of the loop through which the current flows is the smallest.

[0027] Preferably, the positive and negative busbars 4 of the power module 1 are bent to form at least a parallel plane that fits with the positive and negative busbars 5 of the support capacitor 2.

[0028] Preferably, as Figure 4 shown in the figure, the positive and negative busbars 4 of the power module 1 are bent to form a first horizontal plane 41, a vertical plane 42, and a second horizontal plane 43 in sequence. The positive and negative busbars 5 of the support capacitor 2 are horizontally and vertically bent to fit with the second horizontal plane 43 of the positive and negative busbars 4 of the power module 1 and are connected in parallel by welding 10.

[0029] Preferably, the second horizontal plane 43 of the positive and negative busbars 4 of the power module 1 and the first horizontal plane 41 form opposite current directions, and at this time, the area of the loop through which the current flows is the smallest. The second horizontal plane 43 of the positive and negative busbars 4 of the power module 1 and the horizontal plane 51 of the positive and negative busbars 5 of the support capacitor 2 form opposite current directions, and at this time, the area of the loop through which the current flows is the smallest. The vertical plane 42 of the positive and negative busbars 4 of the power module 1 and the vertical plane 52 of the positive and negative busbars 5 of the support capacitor 2 form opposite current directions, and at this time, the area of the loop through which the current flows is the smallest.

[0030] Preferably, the distance between the first horizontal plane 41 and the second horizontal plane 43 of the positive and negative busbars 4 of the power module 1 is as small as possible, and a preferable value is less than 5 mm. The distance between the vertical plane 42 of the positive and negative busbars 4 of the power module 1 and the vertical plane 52 of the positive and negative busbars 5 of the support capacitor 2 is as small as possible, and a preferable value is less than 5 mm. At this time, the area of the loop through which the current flows is the smallest.

[0031] Preferably, the height between the positive and negative busbars 4 extending from the side of the power module 1 body and the positive and negative busbars 5 extending from the side of the support capacitor 2 body is as small as possible, and a preferable value is less than 3 mm, or they are flush.

[0032] Preferably, the welding method for the positive and negative busbars 5 of the support capacitor 2 to be in contact with the second horizontal plane 43 of the positive and negative busbars 4 of the power module 1 is laser welding.

[0033] In this structure, the positive and negative busbars 4 of the power module 1 are extended and bent by 180° to form a connection surface in the same direction as the positive and negative busbars 5 of the support capacitor 2. However, according to the structural arrangement of the power module 1 and the support capacitor 2, there can be various deformations, not limited to the extension and bending of the positive and negative busbars 4 of the power module 1. Similarly, the positive and negative busbars 5 of the support capacitor 2 can also be extended and bent. Finally, after the positive and negative busbars of the power module 1 and the support capacitor 2 are arranged in the same direction at the connection position, welding, or connection with bolts and inserts can be used.

[0034] Such as Figure 4 shown, the positive and negative busbars 4 of the power module 1 extend along the installation plane, and then are bent by 180° and extended to the welding position above the power module 1 body; after the positive and negative busbars 5 of the support capacitor 2 extend along the installation plane, they are bent twice, namely the vertical plane 52 and the horizontal plane 51, and extended to the welding position. This makes the current directions of the positive and negative busbars 4 of the power module 1 and the positive and negative busbars 5 of the support capacitor 2 opposite at the connection, and at this time, the area of the loop through which the current flows is the smallest; moreover, the vertical plane 42 of the positive and negative busbars 4 of the power module 1 and the vertical plane 52 of the positive and negative busbars 5 of the support capacitor 2 form opposite current directions, and the distance between the vertical plane 42 of the positive and negative busbars 4 of the power module 1 and the vertical plane 52 of the positive and negative busbars 5 of the support capacitor 2 is less than 5 mm, and at this time, the area of the loop through which the current flows is the smallest; the height between the positive and negative busbars 4 extending from the side of the power module 1 body and the positive and negative busbars 5 extending from the side of the support capacitor 2 is less than 3 mm.

[0035] In this structure, the positive and negative busbars between the power module and the support capacitor are connected together by welding or two sets of bolts and inserts respectively. The current flows from the busbar of the support capacitor to the busbar of the power module. Among them, the current directions of the busbars flowing through the connection of the busbars are opposite, and the area of the loop through which the current flows is the smallest, that is, a×h in Equation 2 is the smallest. Then, according to Equation 2, the stray inductance L is the smallest, so as to reduce the stray inductance of the main circuit connecting the power module and the support capacitor.

[0036] In this structure, the positive and negative busbars 4 of the power module 1 and the positive and negative busbars 5 of the support capacitor 2 are connected by welding 10, and the connection joint surface is in the parallel direction of the installation plane of the power module. Among them, the current flows from the busbar 4 to the busbar 5, and the current direction is as Figures 3 to 4As shown in the figure, I1 is the current on the first horizontal plane 41 of the busbar 4 of the power module 1, I2 is the current on the vertical plane 42 of the busbar 4 of the power module 1, I3 is the current on the second horizontal plane of the busbar 4 of the power module 1, I4 is the current on the horizontal plane 51 of the busbar 5 of the support capacitor 2, and I5 is the current on the vertical plane 52 of the busbar 5 of the support capacitor 2; the distance between the second horizontal plane 43 and the first horizontal plane 41 of the busbar 4 of the power module 1 is as small as possible. Since the directions of I1 and I3 are opposite, the loop area through which the current flows is minimized at this time, reducing the stray inductance at this location; the second horizontal plane 43 is connected to the horizontal plane 51 of the busbar 5 of the support capacitor 2. Since the directions of I3 and I4 are opposite, the loop area through which the current flows is minimized at this time, reducing the stray inductance at this location; the distance between the vertical plane 42 of the busbar 4 of the power module 1 and the vertical plane 52 of the busbar 5 of the support capacitor 2 is as small as possible. At the same time, the height between the busbar 4 extending from the side of the power module 1 and the busbar 5 extending from the side of the support capacitor 2 is as small as possible. At this time, the directions of I2 and I5 are opposite, and the loop area through which the current flows is minimized at this time, reducing the stray inductance at this location.

[0037] Therefore, adopting this structure can solve the problem of excessive stray inductance at the connection between the power module 1 and the support capacitor 2, reduce the stray inductance in the areas of spacing A and spacing B, thereby reducing the stray inductance of the entire main circuit, reducing the surge voltage caused by the stray inductance, avoiding the risk of breakdown of the power module, ensuring the switching characteristics of the power module, and improving the reliability of motor drive control.

Claims

1. The main circuit layout structure of a three-phase AC motor drive system controller, comprising a power module with positive and negative busbars and a support capacitor with positive and negative busbars, wherein the positive and negative busbars of the power module and the positive and negative busbars of the support capacitor are respectively connected by welding to form an inverter main circuit; characterized in that : After the positive and negative busbars of the power module horizontally extend to the outside of the power module body along the installation plane, they are bent by 180° and extended above the power module body. The positive and negative busbars of the support capacitor horizontally extend to the surfaces of the positive and negative busbars of the power module along the installation plane and are attached. The attachment part of the positive and negative busbars of the support capacitor and the positive and negative busbars of the power module is connected by welding, so that the current directions of the positive and negative busbars of the power module and the positive and negative busbars of the support capacitor are opposite at the connection part, and at this time the area of the loop through which the current flows is the smallest; The positive and negative busbars of the power module are bent in sequence to form a first horizontal plane, a vertical plane and a second horizontal plane. The positive and negative busbars of the support capacitor are attached to the second horizontal plane of the positive and negative busbars of the power module after being horizontally and vertically bent and are connected in parallel by welding; The distance between the first horizontal plane and the second horizontal plane of the positive and negative busbars of the power module is as small as possible, and the distance between the vertical plane of the positive and negative busbars of the power module and the vertical plane of the positive and negative busbars of the support capacitor is as small as possible. At this time, the area of the loop through which the current flows is the smallest.

2. The main circuit layout structure of the three-phase AC motor drive system controller according to claim 1, characterized in that: The positive and negative busbars of the power module are bent to form at least a parallel plane that fits the positive and negative busbars of the support capacitor.

3. The main circuit layout structure of the three-phase AC motor drive system controller according to claim 1, characterized in that: The second horizontal plane of the positive and negative busbars of the power module forms an opposite current direction to the first horizontal plane. At this time, the area of the loop through which the current flows is the smallest. The second horizontal plane of the positive and negative busbars of the power module forms an opposite current direction to the horizontal plane of the positive and negative busbars of the support capacitor. At this time, the area of the loop through which the current flows is the smallest. The vertical plane of the positive and negative busbars of the power module forms an opposite current direction to the vertical plane of the positive and negative busbars of the support capacitor. At this time, the area of the loop through which the current flows is the smallest.

4. The main circuit layout structure of the three-phase AC motor drive system controller according to claim 1, characterized in that: The height between the positive and negative busbars extending from the side of the power module body and the positive and negative busbars extending from the side of the support capacitor is as small as possible or flush.

5. The main circuit layout structure of the three-phase AC motor drive system controller according to claim 1, characterized in that: The welding method for the positive and negative busbars of the support capacitor to be attached to the second horizontal plane of the positive and negative busbars of the power module is laser welding.

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