Patent ID: 8767424
Filing Date: 2014-07-01
Classification: H02M,H03K,Y02B

Abstract:
1. A power conversion apparatus which converts a direct current into an N-phase alternate current, where N is an integer equal to 3 or greater, and supplies the converted N-phase alternate current to an inductor working as a load and provided for each phase, said power conversion apparatus comprising: 2N arms each including a switching unit having a field-effect transistor representing a switching element and a diode connected in parallel, said switching element becoming conductive according to a control signal to be supplied, such that a flow path of a regenerative current of the inductor is formed, said diode having the regenerative current of the inductor flow in a forward direction, and said field-effect transistor being placed such that the regenerative current of the inductor flows from a source toward a drain on said field-effect transistor; N legs each provided in a corresponding one of N-phases, formed with said 2N arms serially connected in a pair, having ends connected to a direct-current power source, and having a mid point connected to the inductor of the corresponding one of the N-phases; a load current determining unit configured to determine an amount of a current flowing into the inductor provided in each of the N-phases; a temperature measuring unit configured to measure a temperature and output a result of the measurement as a temperature value; a threshold designating unit configured to designate, as a threshold current and based on the temperature value output from said temperature measuring unit, a current amount at which (i) an on-resistance of said switching element obtained based on a characteristic of said switching element for a current flowing only through said switching element becomes equal to (ii) an on-resistance of said diode obtained based on a characteristic of said diode for a current flowing only through said diode, the current flowing only through said switching element and the current flowing only through said diode both flowing in the forward direction with respect to said diode and having a same value; and a prohibition control unit configured to prohibit supplying the control signal to said switching element included in said leg of the corresponding N-phase, when the amount of the current, for each of the N-phases, determined by said load current determining unit is greater than the threshold current designated by said threshold designating unit.