US-20260124940-A1 - POWER CONVERSION DEVICE

Abstract

A power conversion device includes a negative side wiring and a positive side wiring. The positive side wiring is provided with a coil of a motor. The power conversion device uses a coil to boost a DC voltage. The power conversion device includes a Y capacitor provided between the positive side wiring and a ground, and a Y capacitor having a capacitance larger than capacitance of the Y capacitor and provided between the negative side wiring and the ground.

Inventors

• Seido ARAKI
• Tatsuya Furukawa
• Yuji Mochizuki

Assignees

• DENSO CORPORATION
• TOYOTA JIDOSHA KABUSHIKI KAISHA

Dates

Publication Date

20260507

Application Date

20260105

Priority Date

20230711

Claims (5)

1. 1 . A power conversion device for stepping up or stepping down a DC voltage, comprising: a negative side wiring; a positive side wiring; a transformer circuit including a coil provided on the positive side wiring; a first ground capacitor provided between the positive side wiring and a ground; and a second ground capacitor having a capacitance larger than a capacitance of the first ground capacitor and provided between the negative side wiring and the ground.
2. 2 . The power conversion device according to claim 1 , further comprising, a first inter-wiring capacitor provided between the negative side wiring and the positive side wiring at one end side of the transformer circuit, and a second inter-wiring capacitor provided between the negative side wiring and the positive side wiring at the other end of the transformer circuit, wherein the second ground capacitor is provided between the first inter-wiring capacitor and the second inter-wiring capacitor.
3. 3 . The power conversion device according to claim 1 , wherein a difference between a capacitance of the first ground capacitor and the capacitance of the second ground capacitor is equal to a parasitic capacitance of the coil.
4. 4 . The power conversion device according to claim 1 , further comprising, a motor including the coil, and an inverter circuit including a plurality of switching elements and supplying power to the motor.
5. 5 . The power conversion device according to claim 4 , further comprising, a filter provided between the negative side wiring and the positive side wiring to suppress noise due to switching operations of the plurality of switching elements.

Description

CROSS REFERENCE TO RELATED APPLICATIONS The present application is a continuation application of International Patent Application No. PCT/JP2024/022493 filed on June 21, 2024, which designated the U.S. and claims the benefit of priority from Japanese Patent Application No. 2023-114030 filed in Japan filed on July 11, 2023, the entire disclosure of the above application is incorporated herein by reference. TECHNICAL FIELD The present disclosure relates to a power conversion device. BACKGROUND An example of a power conversion device is a motor drive system. SUMMARY The disclosed object is to provide a power conversion device capable of suppressing noise imbalance. A power conversion device that steps up or steps down a DC voltage includes: a negative side wiring, a positive side wiring, a transformer circuit including a coil provided on the positive side wiring, a first ground capacitor provided between the positive side wiring and a ground, and a second ground capacitor having a capacitance larger than the capacitance of the first ground capacitor and provided between the negative side wiring and the ground. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a circuit diagram showing a schematic configuration of a power conversion device; FIG. 2 is a circuit diagram showing a schematic configuration of a motor; and FIG. 3 is a circuit diagram showing a schematic configuration of a power conversion device according to a modified example. DETAILED DESCRIPTION An example of a power conversion device is a motor drive system. The motor drive system includes an inverter including a switching element connected between a DC connection terminal and an AC connection terminal, and a motor including a plurality of coils connected to the AC connection terminal. In order to suppress noise in the negative side and positive side wiring, the power conversion device may be configured to include capacitors between the negative side wiring and ground and between the positive side wiring and ground. However, in the power conversion device, there is a risk that a noise imbalance will occur between the negative side wiring and the positive side wiring due to a parasitic capacitance of the coil. The disclosed object is to provide a power conversion device capable of suppressing noise imbalance. A power conversion device that steps up or steps down a DC voltage includes: a negative side wiring, a positive side wiring, a transformer circuit including a coil provided on the positive side wiring, a first ground capacitor provided between the positive side wiring and a ground, and a second ground capacitor having a capacitance larger than the capacitance of the first ground capacitor and provided between the negative side wiring and the ground. The power conversion device includes the second ground capacitor, which has a capacitance larger than that of the first capacitor and is provided between the negative side wiring and the ground. Therefore, even if parasitic capacitance is formed in the coil provided in the positive side wiring, the power conversion device can suppress a deviation between the capacitor capacitance between the negative side wiring and the ground and the capacitor capacitance between the positive side wiring and the ground. Therefore, the power conversion device can suppress the imbalance of noise between the negative side wiring side and the positive side wiring side. The disclosed aspects in this specification adopt different technical solutions from each other in order to achieve their respective objectives. The objects, features, and advantages disclosed in this specification will become apparent by referring to following detailed descriptions and accompanying drawings. Embodiment: Hereinafter, various embodiments for carrying out the present disclosure will be described with reference to the drawings. In each embodiment, portions corresponding to those described in the preceding embodiment are denoted by the same reference numerals, and redundant descriptions will be omitted in some cases. In each of the embodiments, when only a part of the configuration is explained, the other part of the embodiment can be referred to the other embodiment explained previously and applied. A power conversion device 100 will be described with reference to FIG. 1. FIG. 1 illustrates the power conversion device 100 in a state where a charging stand 300 is connected. The power conversion device 100 is configured to be mountable on, for example, a mobile object. Examples of the mobile body include automobiles, trains, and aircraft. In the present embodiment, an automobile is used as an example of the mobile body. In the present embodiment, as examples of automobiles, electric vehicles or hybrid vehicles equipped with a rechargeable battery 200 are adopted. The automobile includes a power conversion device 100, a battery 200, and the like. The battery 200 corresponds to a power source or a power supply. The power conversion device 100 includes