Sensorless BLDC Control AN1160B - Microchip Technology

2008-2012 Microchip Technology 1AN1160 INTRODUCTIONThis application note describes a Sensorless BrushlessDirect Current ( bldc ) motor Control algorithm that isimplemented using a dsPIC Digital Signal Controller(DSC) or a PIC24 microcontroller. The algorithm worksutilizing a majority function for digitally filtering theBack-Electromotive Force (BEMF). Each phase of themotor is filtered to determine when to commutate themotor drive voltages. This Control technique excludesthe need for discrete, low-pass filtering hardware andoff-chip comparators. It should be pointed out that allthe discussions here, and the application software,assume a 3-phase motor has to be used. The motorcontrol algorithm described here has four main parts: Sampling trapezoidal BEMF signals using the microcontroller s Analog-to-Digital Converter (ADC) PWM ON-side ADC sampling to reduce noise and solve low-inductance problems Comparing the trapezoidal BEMF signals to VBUS/2 to detect the zero-crossing points Filtering the signals coming from the comparisons using a majority function f

Nov 29, 2011 · impedance of the windings times the current. Generally speaking, if the commutated voltage is set to maximum, regardless of the motor’s speed or torque production, the motor will be dr iven inefficiently with the wasted energy heating the motor’s windings. For the proper control necessary, Pulse-Width Modulation

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  Control, Heating, Impedance, Bldc, Sensorless, Sensorless bldc control

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