Inverter drive device and electrically driven vehicle system using the same

An apparatus comprising:

• a microcomputer;
• an inverter drive device configured to switch a first control mode, a second control mode, and a third control mode on the basis of vehicle speed information in a motor control device that controls a power converter that drives a polyphase motor by a PWM pulse signal based on a carrier signal;
• and
• a voltage timing generator, wherein
• the first control mode is configured to update a command voltage signal to the power converter only on a ridge side or a trough side of the carrier signal,
• the second control mode is configured to update a command voltage signal to the power converter both on a ridge side and a trough side of the carrier signal,
• the third control mode is configured to update a command voltage signal to the power converter only once of ridge-trough-ridge or trough-ridge-trough of the carrier signal, and
• the voltage timing generator changes an update cycle according to a processing load factor of the microcomputer on the basis of a flow of the voltage timing generator.