閉環控制在無刷直流電機系統中的應用

　　無刷直流電機因其可靠性高、效率高、噪音低而取代傳統的直流電機。這些產品在幾乎所有領域都很流行，如消費電子、家用電器和工業控制。高性能無刷直流電機控制系統的開發需要更高的精度。這是通過在大多數BLDC控制系統中使用閉環控制來實現的。

　　無刷直流電機

　　直流無刷電機在直流電機上的優點是：

　　效率高

　　更可靠和無電弧換向-無刷維修

　　更高的速度和功率大小比

　　定子內產生熱量-易于去除。

　　低慣量無換向器

　　更高的加速率

　　BLDC motors are more efficient than brushed DC motors. For the same input power， a BLDC motor converts more electrical power into mechanical power than a brushed motor because of the absence of friction due to brushes. In a brushed motor design， the brushes are used to change the poles of the electromagnet in order to keep the motor spinning. Due to this lack of brushes， there is nothing to mechanically handle the polarity changes. As a result， an electronic controller is required to continuously switch the phase of the winding which will keep the motor spinning. To do this， the stator windings are energized in a particular sequence as seen in Figure 1. BLDC motors have three phases. With this topology， to move the motor， two phases are driven during each commutation cycle. One phase is driven high （VMotor） and the other is driven low （GND）。 The remaining phase is left floating. With every commutation step， the motor will move 60 degrees. Upon completion of all cycles， the motor will have moved a complete 360 degrees.