Analysis of input pulse in brushless dc motor
NewThink Motor / 2018-02-02 1337
Limited Angle brushless dc motor of the input pulse width modulation (PWM), with the change of the PWM duty ratio change the direction of the electric current flows through the motor, in order to change the motor rotation speed and steering, because on the motor armature is PWM waveform, namely a series of square wave form of voltage waveform, so the first step is how to modeling will be at the ends of the normal operation of the PWM wave and motor armature voltage, electric current, motor rotation angular velocity and the rotation Angle, etc.
The model consists of three main processing modules, namely PWM analytical module, current calculation module and Angle calculation module.
Input signal of the motor is standard dc or ac voltage signal, and limited Angle brushless dc motor here is PWM square wave input excitation signal, so the modeling priority is how to build relationships with both ends of the motor armature voltage PWM square wave signal, which is the whole modeling difficulty.
Because the PWM is by changing its own high and low level of duty ratios of the positive and negative control current and motor and reversing, so after comprehensive consideration, decided to adopt the input PWM method for sampling and counting is presented in this PWM relations with both ends of the motor armature voltage modeling a new train of thought, timing for the data storage and the count value of zero. In general, the sampling clock frequency is about 6-10 times of the PWM clock, i.e., sampling 6-10 times per PWM cycle to ensure the sampling accuracy.