To enable application of high switching frequency at a low cost by applying a high speed switching type to a drive signal in which a chopper signal is synthesized, and applying a low speed switching type to a drive signal in which the chopper signal is not synthesized, in a photocoupling element insulating the drive signal.
A drive signal circuit is provided with a microcomputer 1, high speed photocouplers 24-26, low speed photocouplers 27-29, etc. A power module 42 includes driver circuits 30-35 and IGBT's 36-41. Drive signals A+, B+, C+ have been already synthesized in a chopper signal, but may be synthesized by using a circuit outside the microcomputer. By making the chopper frequency higher than or equal to 5 kHz, the high speed photocouplers 24-26 are obtained. The driver circuits 30-35 are mounted in a power module, but photocouplers including driver circuits may be used, or driver circuits may be individually added.
TAKAGI JUNICHI
TAKEMOTO AKINOBU
ISHII MAKOTO
