This paper introduces the principle of simple sine wave brushless dc motor control and its implementation
simple sine wave control principle
simple sine wave control is by controlling the motor sine phase voltage amplitude and phase to achieve the purpose of control motor current. Usually through some form of motor end line on voltage for producing sine phase voltage winding ends. Common way of generating is: the sinusoidal PWM and space vector PWM. Because sine PWM principle is simple and easy to implement, so simple is often used in sine wave control as a PWM generation. Brushless dc motor, including the Ux, Uy, offers for the bridge arm voltage, Ua, Ub, Uc as the phase voltage of the motor winding, the following for different kinds of PWM modulation method is introduced based on the structure.
(1)Three-phase sinusoidal modulation PWM
most common three-phase SPWM sine PWM generation, the three ends of motor on the sine voltage signal phase difference of 120 degrees, due to the neutral point is zero, so the motor also for sinusoidal phase voltage, and phase with the applied sinusoidal voltage is the same. (1)Switching loss minimum sine PWM
unlike common SPWM, the switching loss minimum sine PWM, imposed on the motor end line voltage Ua, Ub, Uc is not a sine wave voltage, center of the motor voltage is not zero, but still for sinusoidal motor phase voltage. This
class control mode for the line voltage control.
the Ux, Uy, offers for the motor end line voltage, Ua, Ub, Uc for motor phase voltage and phase voltage phase difference of 120 degrees. Ux, Uy, offers its relationship with Ua, Ub, Uc is as follows:
after the merger, Ux, Uy, offers the following:
visible when switching loss minimum sine PWM is adopted, the Ux, Uy, offers phase difference of 120 degrees, and as the piecewise function form, is not a sine voltage, the motor phase voltage Ua, Ub, Uc for sinusoidal voltage. And 120 degrees in the area to end line voltage is 0, the corresponding switch tube often open or closed. So compared with three-phase sinusoidal PWM, switching losses reduce 1/3.
by controlling the Ux, Uy, offers the phase and amplitude which can control the Ux, Uy, offers, achieve the goal of control current.
