Patent ID: 8369119

Claim:
An inverter drive power supply circuit for driving a plurality of inverter switching devices that form an inverter circuit, comprising: a number N of transformers (N is an integer equal to or larger than 2) adapted to a push-pull method, each having a first winding and a second winding for a primary winding and a first winding and a second winding for a secondary winding, and supplying an output voltage of the secondary winding to the inverter switching devices, wherein one end of the respective first windings of the number N of the primary windings and one end of the respective second windings of the number N of the primary windings are connected to each other and connected to a primary-side power source that applies a primary-side voltage, the other end of the respective first windings of the number N of the primary windings are connected to each other and are connected in parallel to the primary-side power source via a first power supply control section, and the other end of the respective second windings of the number N of the primary windings are connected to each other and are connected in parallel to the primary-side power source via a second power supply control section, and a saturation magnetic flux density of a core of each transformer is set to a value that is equal to or higher than {1 +1/(N−1)} times a required saturation magnetic flux density, which is a minimum saturation magnetic flux density required to prevent magnetic saturation from being caused even by a largest value of a current that flows in the primary windings in a normal state where there is no defective portion in the circuit in which the number N of the transformers are formed.