Patent ID: 9634586
Date: 2017-04-25
CPC Classifications: H02M,H02P

Claim:
1. A fail-safe apparatus for an inverter that performs driving and electric-power generation by use of a synchronous motor in which a permanent magnet is utilized as a magnetic-field magnet, the fail-safe apparatus for the inverter comprising: a three-phase inverter circuit that has a switching device for performing electric-power conversion; an excessive voltage detection circuit that detects an excessive voltage by monitoring a direct current (DC) power source voltage of the inverter; and a drive switching circuit that switches a driving method for the switching device from a three-phase pulse width modulation (PWM) driving mode that controls an operation of the three-phase inverter based on a PWM signal to a three-phase short-circuiting driving mode that enables the three-phase inverter to be short-circuited in response to receiving an excessive voltage determination signal from the excessive voltage detection circuit, wherein the drive switching circuit comprises a three-phase PWM driving circuit that generates an upper-arm PWM signal and a lower-arm PWM signal, a three-phase short-circuit driving circuit that generates a first output signal and a second output signal in accordance with the excessive voltage determination signal, an AND circuit that generates an upper-arm gate control signal based on the upper-arm PWM signal and the first output signal, and an OR circuit that generates an lower-arm gate control signal based on the lower-arm PWM signal and the second output signal.