While BLDC motors are mechanically relatively simple, they do require sophisticated control electronics and regulated power supplies. The designer is faced with the challenge of dealing with a three-phase high-power system that demands precise control to run efficiently.
Figure 3 shows a typical arrangement for driving a BLDC motor with Hall-effect sensors. (The control of a sensorless BLDC motor using back EMF measurement will be covered in a future article.) This system shows the three coils of the motor arranged in a “Y” formation, a Microchip PIC18F2431 microcontroller, an insulated-gate bipolar transistor (IGBT) driver, and a three-phase inverter comprising six IGBTs (metal oxide semiconductor field effect transistors (MOSFETs) can also be used for the high-power switching). The output from the microcontroller (mirrored by the IGBT driver) comprises pulse width modulated (PWM) signals that determine the average voltage and average current to the coils (and hence motor speed and torque). The motor uses three Hall-effect sensors (A, B, and C) to indicate rotor position. The rotor itself uses two pairs of permanent magnets to generate the magnetic flux.
While BLDC motors are mechanically relatively simple, they do require sophisticated control electronics and regulated power supplies. The designer is faced with the challenge of dealing with a three-phase high-power system that demands precise control to run efficiently. Figure 3 shows a typical arrangement for driving a BLDC motor with Hall-effect sensors. (The control of a sensorless BLDC motor using back EMF measurement will be covered in a future article.) This system shows the three coils of the motor arranged in a “Y” formation, a Microchip PIC18F2431 microcontroller, an insulated-gate bipolar transistor (IGBT) driver, and a three-phase inverter comprising six IGBTs (metal oxide semiconductor field effect transistors (MOSFETs) can also be used for the high-power switching). The output from the microcontroller (mirrored by the IGBT driver) comprises pulse width modulated (PWM) signals that determine the average voltage and average current to the coils (and hence motor speed and torque). The motor uses three Hall-effect sensors (A, B, and C) to indicate rotor position. The rotor itself uses two pairs of permanent magnets to generate the magnetic flux.
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