Study on Characteristics of Motor Output Power Depending on Current Sensor Response in Eco-Friendly Vehicles

The current sensor for motor control is one of the main components in inverters for eco-friendly vehicles. Recently, as the higher performance of torque control has become required, the current sensor measurement error and accuracy of motor controls have become more significant. Since the response time of the sensor affects the motor output power, the response delay of the sensor causes measurement errors of the current. Accordingly, the voltage vector changes, and a motor output power deviation occurs. In the case of the large response delay of the sensor, as motor speed increases, then difference between motoring and generating output power becomes larger and larger. This results in the deterioration of power performance in high-speed operation. The deviation of the voltage vector magnitude is the main cause of motor output power deviation and imbalance through the simulation. In addition, motor output power deviation and imbalance between motoring and generating power can be reduced by compensating the delay angle of the sensor according to motor speed. In this paper, to overcome the motor output power imbalance due to the response delay of the current sensor, we propose two compensation methods as follows. The first method involves compensating the current reference according to the speed of the motor and the response time of the current sensor. The second method involves compensating the angle of the position sensor according to the speed of the motor and the response time of the current sensor. Simulations and experiments have demonstrated the effectiveness of these methods. By using the proposed methods, the motor output power deviation can be reduced from -5.8% to 0.4% in the case of a current sensor increasing a 5usec delay. As a result, it can be expected to improve driving performance and fuel efficiency.