System and method for testing performance of frequency changer

The invention discloses a system and method for testing the performance of a frequency changer. The system comprises an asynchronous motor connected with the frequency changer in a drive manner, a torque speed sensor, a magnetic powder brake, a touch screen and a PLC (programmable logic controller) used for processing torque, speed and efficiency value, wherein the torque speed sensor is electrically connected with the asynchronous motor and used for acquiring a torque signal and a speed pulse signal on an output shaft of the asynchronous motor; the magnetic powder brake is electrically connected with the torque speed sensor and used for monitoring the torque signal and the speed pulse signal of the torque speed sensor; an analogue acquisition port of the PLC is used for acquiring the torque signal and the speed pulse signal and making a calculation; the touch screen is communicatively connected with the PLC. According to the system, through induction of the torque speed sensor and adjustment of the magnetic powder brake, the efficiency value can be calculated while the torque and speed of the frequency changer are tested; by adjusting a load of the magnetic powder brake, the frequency changer can be tested in terms of the torque control output in each speed range and the speed precision under different load situations.