| 摘要 |
PROBLEM TO BE SOLVED: To attain stable operation of a three-phase rectifier, by changing the dead time of control pulses of control elements on positive and negative potential sides of respective arms, based on input phase voltage. SOLUTION: A dead time duration computing circuit detects input phase voltage, computes desired dead time duration so as to meet the voltage value, generates a control pulse which has generated dead time based on computed results to supply to a drive circuit. Two control signals as a pair for controlling meet one control pulse, the other control pulse is inverted by an inverting circuit to be generated, and these control pulses are applied to a control element. The dead time of the control pulses of control elements on positive and negative potential sides of the respective arms can be changed with input phase voltage. It is thus possible to attain a three-phase rectifier power factor improving circuit which can prevent failures which are caused by simultaneous on-operations of the respective arms, and has few harmonic components. |
