JP-2026075186-A - Smoothing capacitor module

Abstract

[Challenge] To effectively suppress common-mode noise. [Solution] This is a smoothing capacitor module 20 attached to a predetermined metal member 1a. It comprises a positive busbar 53 and a negative busbar 54 connected to the positive terminal 21a and negative terminal 21b of a capacitor cell 21. The positive busbar 53 faces the metal member 1a via a positive-side electrical insulating layer 51, and the negative busbar 54 faces the metal member 1a via a negative-side electrical insulating layer 51. The positive-side capacitance C1 generated between the positive busbar 53 and the metal member 1a and the negative-side capacitance C2 generated between the negative busbar 54 and the metal member 1a are equalized. [Selection Diagram] Figure 7

Inventors

• 山野上 耕一

Assignees

• Ｍａｚｄａ Ｉｍａｓｅｎ Ｅｌｅｃｔｒｉｃ Ｄｒｉｖｅ株式会社

Dates

Publication Date

20260508

Application Date

20241022

Claims (6)

1. A smoothing capacitor module that is attached to a predetermined metal member and installed so as to be electrically interposed between a pair of wires to which positive and negative voltages are applied, At least one capacitor cell, A positive busbar connected to the positive terminal of the capacitor cell, A negative busbar connected to the negative terminal of the capacitor cell, Equipped with, The positive electrode busbar faces the metal member via the positive electrode side electrical insulating layer, and the negative electrode busbar faces the metal member via the negative electrode side electrical insulating layer. A smoothing capacitor module in which the positive electrode capacitance generated between the positive electrode busbar and the metal member and the negative electrode capacitance generated between the negative electrode busbar and the metal member are equalized.
2. In the smoothing capacitor module according to claim 1, A smoothing capacitor module in which the positive electrode side electrical insulating layer and the negative electrode side electrical insulating layer are made of the same material, and the positive electrode side capacitance and the negative electrode side capacitance are equalized by equalizing the surface area of the opposing surfaces of the positive electrode busbar and the negative electrode busbar.
3. In the smoothing capacitor module according to claim 1, A smoothing capacitor module in which the surface areas of the opposing surfaces of the positive and negative busbars are different, and the capacitance of the positive side and the capacitance of the negative side are equalized by adjusting the relative permittivity of the positive side electrical insulating layer and the negative side electrical insulating layer.
4. In the smoothing capacitor module according to claim 1, A smoothing capacitor module in which the surface areas of the opposing surfaces of the positive and negative busbars are different, and the capacitance of the positive side and the capacitance of the negative side are equalized by adjusting the thickness of the positive side electrical insulating layer and the negative side electrical insulating layer, respectively.
5. In the smoothing capacitor module according to claim 1, The present invention further comprises an electrically insulating capacitor case that houses a plurality of capacitor cells, a positive electrode busbar, and a negative electrode busbar, and has a mounting surface that is attached in close contact with a predetermined metal member, The aforementioned positive busbar is A positive terminal protruding outward from the capacitor case and connected to the positive terminal side of the wiring, A positive-side cell terminal connection plate connected to the aforementioned connection terminal and connected to the positive terminals of a plurality of capacitor cells, It has, The aforementioned negative busbar is A negative terminal connection terminal that protrudes outward from the capacitor case and is connected to the negative terminal side of the wiring, A negative-side cell terminal connection plate connected to the aforementioned connection terminal and connected to the negative terminals of multiple capacitor cells, It has, A smoothing capacitor module in which the positive and negative cell terminal connection plates are arranged adjacent to each other in a state that extends along the mounting surface.
6. In the smoothing capacitor module according to claim 5, A smoothing capacitor module in which the positive and negative terminal connection plates of the cell terminals have multiple comb-shaped teeth that extend alternately, and each comb-shaped tooth is arranged to be combined.

Description

The disclosed technology relates to a smoothing capacitor module suitable for automotive power converters. In recent years, the electrification of automobiles, such as hybrid and electric vehicles, has been remarkable. These electric vehicles are equipped with power converters that apply high voltage, such as inverters and converters. In other words, this type of vehicle is equipped with a high-voltage battery ranging from tens to hundreds of volts. This DC voltage is applied to an inverter, converting it into three-phase AC voltages with different phases. This AC voltage is then controlled by the inverter and output to the drive motor. This causes the motor to rotate, and the vehicle to move. In this process, the inverter uses high-frequency switching control, such as around 10 kHz, to generate a smooth sinusoidal AC voltage from the continuous rectangular pulse voltage obtained by switching the switching elements on and off. When switching control is this fast, the periodic voltage changes cause high-frequency currents to flow through the inverter's electrical wiring, generating high-frequency noise. In other words, such high-frequency currents include currents that flow from positive to negative electrical wiring towards the battery (normal mode currents) and currents that flow through both positive and negative electrical wiring, as well as stray capacitance (parasitic capacitance) and ground (earth) (common mode currents). These currents generate electromagnetic noise (normal mode noise and common mode noise). This electromagnetic noise can cause malfunctions in electrical equipment near the inverter, communication interference, and other problems. In contrast, the electrical wiring on the input side of inverters often includes smoothing capacitors to suppress this electromagnetic noise. However, smoothing capacitors alone are insufficient to completely eliminate this electromagnetic noise. Therefore, there is a demand for methods to suppress this noise independently of the installation of smoothing capacitors, and countermeasures have been considered. For example, Patent Document 1 proposes a technique for suppressing normal-mode noise. Specifically, by bringing the positive and negative conductors constituting the smoothing capacitor module close together, the direction of the current flowing through each conductor is reversed. As a result, the magnetic field lines generated by the current flowing through each conductor cancel each other out. Therefore, electromagnetic noise can be suppressed. Japanese Patent Publication No. 2002-44949 This is a simplified diagram of an inverter circuit.This diagram illustrates freewheeling current and through-current in switching control.This figure shows the through-current and ripple voltage.This diagram illustrates the effect of ripple voltage on normal-mode noise.This is a diagram of the first module.This is a diagram illustrating the structure of a busbar.Figure 5 is a schematic perspective view from the direction indicated by arrow Y1.This is a diagram showing the second module.This is a schematic diagram viewed from the direction indicated by arrow Y2 in Figure 8.This section illustrates a modified version of the smoothing capacitor module.This graph shows the effects of applying the disclosed technology. The following describes the disclosed technology. However, the following description is essentially illustrative. For convenience, the directions of the description (front/back, left/right, up/down) will follow the arrows shown in the diagram. <Power Converter> Figure 1 shows a simplified circuit of an inverter 1 as an example of a power converter. This inverter 1 is installed in an electric vehicle. When the vehicle is running on electric power, the inverter 1 converts the DC power from the high-voltage battery 2 into AC power and outputs it to the motor 3. The inverter 1 in the diagram has a pair of input terminals 10, 10. These input terminals 10, 10 are connected to the positive and negative terminals of the battery 2. The inverter 1 has a pair of main wirings 11a, 11b connected to each input terminal 10, and a circuit including a common mode choke coil 12, a smoothing capacitor module 20, a power module 30, etc., is configured between these main wirings 11a, 11b. The common mode choke coil 12 is a known component. The common mode choke coil 12 is positioned near a pair of input terminals 10, 10. The common mode choke coil 12 is constructed by winding a pair of coil wires around a predetermined core with the winding directions reversed. Each of these coil wires is connected to the respective main wirings 11a, 11b, so that the common mode choke coil 12 is positioned midway between the positive and negative main wirings 11a, 11b. As a result, the common-mode current flowing in the same direction through the main wiring 11a and 11b on both the positive and negative sides is weakened by the magnetic field formed by the common-mode choke coil 12. Therefore, t