Abstract
This study developed a hybrid pulse width modulation (PWM) control method intended for use in a high-speed brushless dc (BLDC) motor drive system that uses DC-link single-shunt current measurement. The method is designed to regulate rapid operation and expand the current sensing range of the aforementioned system and measurement, respectively. The operating characteristics of most typical PWM methods for BLDC motors were analyzed, after which, a PWM approach suitable for high-speed operation was identified. On the basis of the selected approach, the measurable range of DC-link single-shunt current was examined mathematically to determine a PWM method that is advantageous for current sensing. The results of the two analyses were used as guidance in formulating the proposed hybrid PWM control algorithm. Finally, the PWM method put forward in this work was verified through experimentation.
Highlights
Brushless dc (BLDC) motors are well suited for high-power and high-speed drive systems because they present advantages such as high power density, low mass and volume, high torque and efficiency, simple control application, and low maintenance needs
A BLDC motor drive consists of a closed-loop current control system, wherein the feedback current of three-phase windings can be obtained either through direct measurement with the current sensors present in each phase or through an estimation based on a single current sensor installed in a DC link
Given that the DC-link current is the same with the phase-winding current in the two-phase conduction operation of a BLDC motor, feedback control current can be obtained from the measured DC-link current and the switching state occurring during pulse width modulation (PWM)
Summary
Brushless dc (BLDC) motors are well suited for high-power and high-speed drive systems because they present advantages such as high power density, low mass and volume, high torque and efficiency, simple control application, and low maintenance needs. The use of current sensors, increases the cost, size, and complexity of a motor drive system and can cause problems stemming from reduced system reliability, such as sensor failures and three-phase current imbalances. These challenges can be addressed by sensing DC-link current from a single-shunt resistor placed in a DC link. Current measurement methods that involve the use of DC-link single-shunt resistors have been explored and applied in many BLDC motor drive systems [4,5,6,7,8]
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