Brushless dc motor controller is composed of synchronous motor controller and driver. This is a typical mechatronics product. Most of stator windings of the synchronous motor controller consists of three-phase symmetric star connection, this is very similar with the three-phase asynchronous motor controller. On the other hand, the rotor is magnetized permanent magnet stuck. In order to detect the polarity of the rotor of motor controller position sensor is installed in the motor controller. The drive is made up of power electronic devices and integrated circuits. Its function is to receive the motor start, stop, and braking signal of the controller, the controller to control the motor start, stop, and braking. Receiving position sensor signals, and the forward and reverse signal, is used to control the inverter bridge open/close of each power tube, to produce a continuous torque; For receiving instructions and speed feedback signal to control and adjust the speed; To provide protection and display, etc. Installed on the shaft of the motor controller rotor position detector is an important part of the brushless dc motor controller. It identifies the each phase of the armature winding when electricity. Its function is equivalent to ordinary brush in dc motor controller. Change the position sensor signal generation time (Phase)Is equal to the change of brush dc motor controller position in space, the characteristics of the brushless dc motor controller has very big effect. There are many structure types of position detector, usually includes a fixed set of detecting element and a rotor position signal generator with the motor controller. In position detector is composed of hall element, hall element is detecting element, motor rotor magnetic pole position itself is a signal generator. In other structures, such as electromagnetic induction type, photoelectric type closed and press the switch type, hole plate is often used as a position signal generator. For example, in the photoelectric type, notch is used to make light with photocell to generate signal; In the electromagnetic induction type, clearance for change of open circuit transformer magnetic circuit, which produces electromotive force in detecting coil, etc.
