Abstract
Recently, applying a dc brushless motor to the electric vehicle has been studied widely. Main ploblem is that the field-weakening control such as used for the induction motors is difficult. because the magnet flux of the motor is fixed. The other is that it needs a position sensor to detect the rotor position.
This paper proposes a sensorless dc brushless motor using current-source PWM inverter. In this system, the inverter angular frequency is calculated by detecting the induced voltages of the motor. And even when supplying voltage to the motor is higher than power source in high speed region, constant power operation is achieved without the field-weakening control. Furthermore, we can maintain the efficiency of the motor.
In this paper. the principle of the control method and the performance characteristics of a sensorless dc brushless motor are discussed. The experimental results of the tested machine shows that the proposed method is very useful for the drive system of electric vehicle.
