Phase voltage sampling circuit and fault diagnosis method of driving axle of PMSM (Permanent Magnet Synchronous Motor)

The invention discloses a phase voltage sampling circuit of a driving axle of a PMSM. The circuit comprises a single-chip microcomputer sampling module, an analog-digital conversion input end of a single-chip microcomputer is connected with one end of a second resistor, one end of a third resistor and one end of a fourth resistor; the other end of the second resistor is connected with one end of a first resistor, a source electrode of an upper bridge arm driving tube, a drain electrode of a lower bridge arm driving tube and a motor wiring harness; the other end of the third resistor is connected to 5V power supply voltage of the single-chip microcomputer; and the other end of the fourth resistor is grounded. The invention also discloses methods for determining short-circuit fault of the driving axle which is powered on initially, open-circuit fault of an upper bridge arm driving axle and open-circuit fault of a lower bridge arm driving axle. The invention also discloses a real-time fault diagnosis method of the driving axle of the PMSM. The phase voltage of the motor is sampled, and compared with the threshold voltage of the driving arm driving tubes of the driving axle to determine fault of the driving axle of the PMSM.