Detection device and detection method for detecting rotor position of permanent magnet synchronous motor

The invention provides a detection device and a detection method for detecting the rotor position of a permanent magnet synchronous motor. The device comprises a DC voltage source, a three-phase full-bridge inverter, a high-resistance resistor and a permanent magnet synchronous motor. The DC voltage source is used for powering up the three-phase full-bridge inverter. The three-phase full-bridge inverter is connected with the permanent magnet synchronous motor. The neutral point of the DC voltage source is grounded. The neutral point of the permanent magnet synchronous motor is grounded by the high-resistance resistor. The method comprises the steps of detecting a voltage applied across the two ends of the high-resistance resistor, adopting the detected voltage as the voltage applied to the neutral point of the permanent magnet synchronous motor, determining the terminal voltage of the permanent magnet synchronous motor, subjecting the terminal voltage by the voltage applied to the neutral point of the permane