A three-phase voltage system needs to be created to run
the BLDC motor. It is provided by 3-phase power stage
with six MOSFET power switches controlled by the
PIC16F877 device on-chip PWM module. In view of the
continuous form of Hall’s sensors signals the detection
block (comparator LM339) of position was used, which
converts those to binary form (Fig.1). Such constructed
internal loop can be used to control the BLDC motor in
open loop system. To vary the speed, the sequence of
commutation should be Pulse Width Modulated (PWM)
at a much higher frequency than the motor frequency. In
the presented work, the lower switches are turned on for
the entire time during the corresponding sequence and the
corresponding upper switch are controlled by the required
duty cycle on PWM. The speed is controlled in a closed
loop system (outer loop) by measuring the actual speed of
the motor (ATMEL AT89c4051 device). To amplify the
speed error and dynamically adjust the PWM duty cycle,
a DCM controller is used.
The main part of this research is to design the speed
controller based on the Dynamic Contraction Method.
The Matlab/Simulink with the Real-Time Toolbox by The
Mathworks was chosen as development environment,
since this is already a well known and widely used tool. It
was used for a fast prototyping of designed DCM
controller, as well as the control system concept, in HiL
tests. The I/O Card MF624 by Humusoft with PC
architecture was chosen as a data acquisition and control
device. The applied general conception gives a possibility
for rapid prototyping of the control system and HiL online
simulation in real time.