Self-propelled aerial work platform with a drive motor shall meet the performance requirements, a permanent magnet three-phase brushless dc motor as the drive motor. Permanent magnet brushless dc motor in the process of work, each phase winding conduction of regular alternation, when winding don't conduction, because of the winding coil storage, will produce inductive electromotive force, the induced emf waveform can be detected in the winding two endpoints. The characteristics of induction electromotive force, can be used to replace the rotor position sensor function, to get directional information. So, there is the structure more simple, more reliable performance permanent magnet brushless dc motor. Combined with the working characteristics of self-propelled aerial work platform, the current mainstream aerial work platform choose brushless dc permanent magnet motor as drive motor. So, what are the advantages of permanent magnet brushless dc motor? Permanent magnet brushless dc motor is produced and developed with digital control technology, therefore, the single-chip microcomputer and DSP digital control is the main control of brushless dc motor. Permanent magnet brushless dc motor is mainly completed the following several aspects of the control. ()Commutation control: for a system with position sensor, according to the position of the sensor signal is regular reversing, correctly realize the phase current switch; For sensorless system, according to the induced electromotive force signal to calculate the reversing point, determine which phase should be electricity, which phase should be without electricity. ()Speed control: the brushless dc motor (BLDCM) speed control on the same principle as a common dc motor and PWM method to control the average voltage of armature, realize the speed control. Using PWM mouth MCU and DSP can be automatically output PWM, make it very easy to find the speed control. ()Reversing control: as long as the change in the power sequence can achieve motor and reversing control.
