Patent ID: 8963524
Filing Date: 2015-02-24
Classification: H03K

Abstract:
1. A drive circuit for switching elements which is applied to a power inverter circuit including a high-potential side switching element and a low-potential side switching element connected to the high-potential side switching element in series, comprising: a first electric path which connects an input terminal and an output terminal of the high-potential side switching element and which includes a high-potential side rectifying device, which blocks a flow of current from the input terminal to the output terminal, and a high-potential side passive element, the high-potential side rectifying device and the high-potential side passive element being arranged sequentially from the input terminal of the high-potential side switching element; a second electric path which connects the output terminal of the high-potential side switching element and an output terminal of the low-potential side switching element and which includes a low-potential side rectifying device, which blocks a flow of current from the output terminal of the high-potential side switching element to the output terminal of the low-potential side switching element, and a low-potential side passive element, the low-potential side rectifying device and the low-potential side passive element being arranged sequentially from the output terminal of the high-potential side switching element; a high-potential side applying unit which applies voltage to a connecting point between the high-potential side rectifying device and the high-potential side passive element during a time period during which the high-potential side switching element is turned on; a high-potential side determining unit which determines that an overcurrent is flowing between the input terminal and the output terminal of the high-potential side switching element based on that an electric potential of the connecting point between the high-potential side rectifying device and the high-potential side passive element exceeding a first specified value even though the high-potential side switching element is change from an OFF state to an ON state; a limiting unit which limits a flow of current between the low-potential side rectifying device and the output terminal of the high-potential side switching element if the high-potential side determining unit determines that the overcurrent is flowing; a low-potential side applying unit which applies voltage to a connecting point between the low-potential side rectifying device and the low-potential side passive element during a time period during which the low-potential side switching element is turned on; and a low-potential side determining unit which determines that an overcurrent is flowing between the input terminal and the output terminal of the high-potential side switching element or between the input terminal and the output terminal of the low-potential side switching element based on an electric potential of the connecting point between the low-potential side rectifying device and the low-potential side passive element exceeding a second specified value even though the low-potential side switching element is changed from an OFF state to an ON state.