Brushless dc motor controller is compared with ac induction motor controller has the following advantages: 1. The rotor using magnets, excitation current is not required. The same power, can obtain larger mechanical power. 2. Rotor copper loss, iron loss, temperature rise is smaller. 3. Start, locked-rotor torque, be helpful for the valve open and close the characteristics of the instantaneous torque required. 4. The output torque of the motor controller is proportional to the working voltage and current. Torque detection circuit is simple and reliable. 5. The average of the adjusted by PWM power supply voltage, the motor controller smooth speed control can be realized. Control of motor speed, drive power circuit simple, reliable and low cost. 6. PWM way lower power supply voltage, start the motor controller can effectively reduce the starting current is small. 7. The dc voltage of the power supply for PWM motor controller. Relative to the ac frequency conversion motor controller of sine wave ac power supply, its control of motor speed, drive circuit of electromagnetic radiation, smaller, less harmonic pollution of power grid. 8. Using closed loop speed control circuit, can be in a constant load torque change speed motor controller.
