Power Conversion Device

Patent metadata

Field	Value
Publication number	US-2016280076-A1
Application number	US-201415033132-A
Country	US
Kind code	A1
Filing date	Oct 14, 2014
Priority date	Nov 7, 2013
Publication date	Sep 29, 2016
Grant date	—

Abstract

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.

First claim

1 . A power conversion device comprising:
an inverter circuit unit which converts a direct current into an alternating current; a step-up circuit unit which steps up a voltage to be applied to the inverter circuit unit; a smoothing capacitor connected electrically in parallel to the inverter circuit unit and the step-up circuit unit; 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.

2 . The power conversion device according to claim 1 , wherein in the discharge control mode, a fixed duty is output which makes a ratio of an input voltage to an output voltage of the step-up circuit unit be generally 1/2.

3 . The power conversion device according to claim 1 , comprising:
a power supply device which supplies a direct-current voltage to the step-up circuit unit; and a second smoothing capacitor connected electrically in parallel to the step-up circuit unit and the power supply device, wherein in the discharge control mode, with the duty command value fixed to the predetermined value, electric charges stored in the smoothing capacitor and the second smoothing capacitor are discharged into the reactor.

4 . The power conversion device according to claim 1 , wherein
the first control mode of the step-up circuit control unit is controlled at a first carrier frequency for controlling the first switching element and second switching element, and the discharge control mode of the step-up circuit control unit is controlled at a second carrier frequency for controlling the first switching element and the second switching element, with the first carrier frequency being lower than the second carrier frequency.

5 . The power conversion device according to claim 1 , comprising a temperature detection circuit unit which detects a coil temperature of the reactor, wherein
when the coil temperature of the reactor detected by the temperature detection circuit unit exceeds a predetermined value, the step-up circuit control unit inhibits discharge operation of stopping switching operation in the discharge control mode.

6 . The power conversion device according to claim 5 , wherein when the discharge operation in the discharge control mode is inhibited, if the coil temperature of the reactor detected by the temperature detection circuit unit falls below the predetermined value, the step-up circuit control unit again allows the switching operation in the discharge control mode.

7 . The power conversion device according to claim 1 , comprising a temperature detection circuit unit which detects the coil temperature of the reactor, wherein
during the first control mode operation, when selecting the discharge control mode, with the coil temperature of the reactor detected by the temperature detection means exceeding the predetermined value, the step-up circuit control unit inhibits the switching operation during a predetermined time period.

Assignees

• Hitachi Automotive Systems Ltd

Inventors

• Yaegaki Sho
• Tamura Hiroshi
• Matsuo Takeshi
• Yamada Hiroyuki
• Akasaka Nobuhiro

Classifications

• H02M7/5395

  by pulse-width modulation · CPC title

• H02M7/48

  using discharge tubes with control electrode or semiconductor devices with control electrode · CPC title

• H02M3/1588

  comprising at least one synchronous rectifier element (H02M3/1582, H02M3/1584 take precedence) · CPC title

• H02M7/537

  using semiconductor devices only, e.g. single switched pulse inverters · CPC title

• B60L2210/14

  Boost converters · CPC title