Patent ID: 7646165

Claim:
A motor driving apparatus receiving an output voltage of an AC power supply, converting the output voltage of the AC power supply into a driving voltage, and outputting the driving voltage to a motor, said apparatus comprising: a converter circuit having a pair of input terminals and a pair of output terminals, and boosting the output voltage of the AC power supply; an inverter circuit for converting an output voltage of the converter circuit into a three-phase AC voltage, and outputting the three-phase AC voltage as a driving voltage to the motor; and said converter circuit comprising a rectifier circuit for rectifying the output voltage of the AC power supply, which is applied to the input terminals, and outputting the rectified voltage to the output terminals, plural capacitors connected in series between the output terminals, and a switch circuit for switching the connections between the respective capacitors and the AC power supply so that the output voltage of the AC power supply is applied to each of the plural capacitors at a cycle shorter than the cycle of the AC power supply; wherein said plural capacitors are first and second capacitors connected in series; and said switch circuit comprises first and second switching elements connected in series, first and second diodes connected in series, which are connected in parallel to the switching elements connected in series, third and fourth diodes connected in series, which are connected in parallel to the switching elements connected in series, a connection node of the first and second diodes being connected to one of the input terminals, a connection node of the third and fourth diodes being connected to the other input terminal, and a connection node of the both switching elements being connected to a connection node of the both capacitors.