Patent ID: 7457136
Filing Date: 2008-11-25
Classification: H02H,H02M

Abstract:
1. An overcurrent protective device for an inverter device, the inverter device including: a power supply having a plus terminal and a grounding terminal; an H-bridge circuit including a group of switching elements connected to the plus terminal of the power supply and a group of switching elements connected to the grounding terminal of the power supply, one of the groups being defined as a first group, the other a second group; a diode connected to each of the switching elements in a back-to-back connection manner; and a switching frequency increase preventing section that prevents an increase of a switching frequency when an overcurrent protective operation is performed, a load being connected to the inverter device, the overcurrent protective device comprising: a current detecting section that detects the amount of a current flowing through the switching elements; a control section that determines whether the inverter device is held in a first state or a second state in correspondence with an input from the current detecting section, wherein the amount of the current flowing through the switching elements when it is determined that the inverter device is held in the second state is greater than the amount of the current flowing through the switching elements when it is determined that the inverter device is held in the first state, wherein, when it is determined that the inverter device is held in the first state, the control section performs a flywheel operation in which drive signals for the first group of the switching elements are maintained in OFF states, and at least one of the switching elements of the second group is maintained in an ON state so that a current circulates through the load and the second group of the switching elements, and wherein, when it is determined that the inverter device is held in the second state, the control section performs a regenerative operation in which the drive signals for all of the switching elements are maintained in OFF states.