Brushless dc motor is more and more popular, its popularity is not a real brushless dc motor using ontology, more concern is the application of the brushless dc motor related technology, such as sine of brushless dc motor drive technology. So, what is the sine of brushless dc motor drive technology? What is the role? We do not prevent to deepen the knowledge in this field.
sine of brushless dc motor drive technology that is based on the brushless motor winding on certain voltage, the sinusoidal current is formed in the brushless motor winding, by controlling the amplitude and phase of the sinusoidal current to achieve the purpose of controlling motor torque. Compared with the traditional square wave control, brushless dc motor phase current is sinusoidal, and continuous change, no change of phase current mutation, so the motor running low noise.
according to the complexity of the control, the sine of brushless dc motor drive technology can be divided into: simple sine wave control and complicated sine wave control. simple sine wave control is by controlling the motor of sinusoidal 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, and therefore is often used in simple sine wave control as a PWM generation. Figure 1 for BLDC control motors structure, of which 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.
figure 1: brushless dc motor control diagram
(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. As shown in figure 2.
figure 3: three-phase SPWM modulation back line voltage
(2)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. So this kind of control mode for the line voltage control. As shown in figure 3:
