Patent ID: 7005813
Filing Date: 2006-02-28
Classification: H02M,H02P

Abstract:
1. A booster circuit for a pre-drive circuit that drives a drive circuit of a brushless direct current single-phase motor, wherein: the drive circuit includes two pairs of serially connected main switching elements, each pair of the serially connected main switching elements being connected between a direct current power supply of the drive circuit and ground, and a motor coil interconnected between pair junctions of the serially connected main switching elements, the pre-drive circuit provides ON/OFF power flow control to the motor coil, and ON/OFF control of the respective main switching elements is prescribed at any timing from any direction, the booster circuit provides a control voltage that exceeds a power supply voltage to turn ON each of the two pairs of serially connected main switching elements of the drive circuit at the direct current power supply side, the booster circuit including a first boost control switching element that turns ON when a first end side of the motor coil reaches a higher electric potential than another end side of the motor coil and charges a first capacitor from the direct current power supply via a first diode, a second boost control switching element that turns ON when the another end side of the motor coil reaches a higher electric potential than the first end side of the motor coil and conducts electricity between a terminal at a side of a connection between the first boost control switching element and the first capacitor and the direct current power supply to increase the electric potential at a side of a junction of the first capacitor and the first diode, and a second capacitor that receives an electric charge and is charged from the first capacitor via a second diode when the second boost control switching element turns ON and is connected between said second diode and a switch terminal at the direct current power supply side of the second boost control switching element, and a boost voltage output is obtained from the connection path between the second diode and the second capacitor.