Patent ID: 9438148
Filing Date: 2016-09-06
CPC Classification: B62D,H02H,H02P

Claim Text:
1. A motor drive device comprising: an inverter circuit for supplying electric power to an electric motor; a power supply relay provided on a power supply line for supplying electric power from a power supply to the inverter circuit; a phase relay provided on a drive line between the inverter circuit and the electric motor, and constituted by a semiconductor switching element; a drive circuit connected to the phase relay and the power supply relay, for driving the phase relay and the power supply relay; a first control line connecting the drive circuit to the phase relay; a first surge-protection circuit provided at a position between the first control line and a motor-side line portion of the drive line connecting the electric motor to the phase relay, and configured to protect the phase relay from surge voltage; a first current reducing circuit configured to reduce a sneak current flowing from the electric motor into the first control line; a second control line connecting the drive circuit to the power supply relay; an electric charge accumulation element provided on an inverter-side line portion of the power supply line between the inverter circuit and the power supply relay, and configured to have a current supply capacity of the inverter circuit; a second surge-protection circuit connected at a position between the second control line and the inverter-side line portion; and a second current reducing circuit configured to reduce a sneak current flowing from the electric charge accumulation element into the second control line.