Hitachi Automotive Systems, Ltd.

Sho Yaegaki

Hiroyuki Yamada

Hiroshi Tamura

Takeshi Matsuo

Nobuhiro Akasaka

Kenji Kubo

Takuma Ono

Yuki Yamabe

A power conversion device capable of suppressing current backflow while also improving current responsiveness and power conversion efficiency is achieved. A snubber capacitor capable of absorbing switching surge is connected to a low-voltage side switching circuit that includes switching elements. Until a predetermined time elapses from when a request to start switching is received, a controller determines that the snubber capacitor has not reached full charge or near-full charge, and asynchronously controls the low-voltage side switching circuit and a high-voltage side switching circuit that includes switching elements. After the predetermined time elapses, the controller synchronously controls the low-voltage side switching circuit and the high-voltage side switching circuit, and also controls a duty ratio of the low-voltage side switching circuit and the high-voltage side switching circuit such that current does not flow back from the low-voltage side switching circuit to the high-voltage side switching circuit.

Power conversion device that generates switching signals

An object is to reduce a discharging time required for discharging residual charges of a capacitor. A power conversion device according to the present invention includes: an inverter circuit unit; a step-up circuit unit; a smoothing capacitor; and a step-up circuit control unit which controls the step-up circuit unit, wherein the step-up circuit unit has a first switching element, a second switching element connected electrically in series to the first switching element, and a reactor having a conducting current controlled by switching operation of the first switching element and the second switching element, and the step-up circuit control unit has a first control mode of controlling the switching operation of the first switching element and the second switching element by changing a duty command value and outputting a stepped up voltage from the step-up circuit unit, and a discharge control mode of discharging electric charges stored in the smoothing capacitor into the reactor, with the duty command value fixed to a predetermined value.

Power conversion device

A surge according to a change of a switching state can be reduced without increasing a torque ripple of a motor. A first switching signal to control switching of a boost converter is generated on the basis of a comparison of a first duty command value and a first triangular wave carrier of the boost converter. A second switching signal to control switching of an inverter is generated on the basis of a comparison of a second duty command value and a second triangular wave carrier of the inverter. In addition, the second triangular wave carrier is generated such that a frequency of the second triangular wave carrier becomes equal to a frequency of the first triangular wave carrier and a phase of the second triangular wave carrier is different from a phase of the first triangular wave carrier by 180 degrees.

Power conversion system

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Hitachinaka, Japan

Sho Yaegaki