CONVERSION DEVICE

• US 20180034386A1
• Filed: 01/28/2016
• Published: 02/01/2018
• Est. Priority Date: 03/05/2015
• Status: Active Grant

• Current Assignee: Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Original Assignee: Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Inventors: Okuda, Yuji, Ayai, Naoki
• Granted Patent: US 10,644,614 B2
• Time in Patent Office: Days
• CPC Class Codes: H02M 1/0048 Circuits or arrangements for reducing losses using snubbers H02M1/34
• CPC Class Codes: H02M 1/007 Plural converter units in cascade push-pull DC/DC converters with pre-regulator H02M3/3374; DC-AC converters following a DC-DC stage including a high frequency transformer H02M7/4807; DC-AC converters following a DC-DC conversion stage generating periodically varying voltages H02M7/4826
• CPC Class Codes: H02M 1/08 Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
• CPC Class Codes: H02M 1/32 Means for protecting converters other than automatic disconnection
• CPC Class Codes: H02M 3/155 using semiconductor devices only
• CPC Class Codes: H02M 3/156 with automatic control of output voltage or current, e.g. switching regulators
• CPC Class Codes: H02M 7/48 using discharge tubes with control electrode or semiconductor devices with control electrode
• CPC Class Codes: H02M 7/797 using semiconductor devices only
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

This conversion device includes: a DC bus with a smoothing capacitor; a first converter provided between a DC power supply and the DC bus to perform DC/DC conversion; a second converter provided between the DC bus and an AC electric path to perform DC/AC or AC/DC conversion by a full-bridge of switching elements; a voltage sensor for detecting voltage between both ends of the capacitor as DC bus voltage; and a control unit which causes a part of an absolute value of an AC waveform, and a DC waveform, to alternately arise as the DC bus voltage by selectively causing the first converter and the second converter to operate in one AC cycle of the AC electric path, the control unit detecting arm short-circuit in the second converter on the basis of a degree of reduction, in the DC bus voltage, that occurs during operation of the second converter.

Claims

1. A conversion device interposed between a DC power supply and an AC electric path, the conversion device comprising:

a DC bus which is provided between the DC power supply and the AC electric path and to which a smoothing capacitor is connected;

a first converter provided between the DC power supply and the DC bus and configured to perform DC/DC conversion;

a second converter provided between the DC bus and the AC electric path and configured to perform DC/AC conversion or AC/DC conversion with use of switching elements connected in a full-bridge form;

a voltage sensor configured to detect voltage between both ends of the capacitor as DC bus voltage; and

a control unit configured to cause a part of an absolute value of an AC waveform, and a DC waveform, to alternately arise as the DC bus voltage by selectively causing the first converter and the second converter to operate in one AC cycle of the AC electric path, the control unit detecting arm short-circuit in the second converter on the basis of a degree of reduction, in the DC bus voltage, that occurs during operation of the second converter.

2. The conversion device according to claim 1, wherein

the degree of reduction is a slope of reduction, and a phenomenon in which the DC bus voltage reduces at a slope steeper than a threshold value is detected as arm short-circuit in the second converter.

3. The conversion device according to claim 1, further comprising a voltage sensor configured to detect input voltage from the DC power supply, wherein the degree of reduction is a difference between the input voltage and the DC bus voltage, and a phenomenon in which the difference exceeds a threshold value is detected as arm short-circuit in the second converter.

4. The conversion device according to claim 1, wherein

when the arm short-circuit is detected, the control unit stops operations of the first converter and the second converter on the basis of a short-circuit withstand capability of the switching elements.

5. The conversion device according to claim 2, wherein

when the arm short-circuit is detected, the control unit stops operations of the first converter and the second converter on the basis of a short-circuit withstand capability of the switching elements.

6. The conversion device according to claim 3, wherein

when the arm short-circuit is detected, the control unit stops operations of the first converter and the second converter on the basis of a short-circuit withstand capability of the switching elements.