Most of the current sensorless control schemes for BLDC (Brushless DC) motor are based on full-bridge driver. However, half-bridge driver draws a lot of attention due to its simpler structure, smaller occupied volume, lower power loss, easier control scheme and lower production cost, and it has been successfully utilized in several applications. Inspired by these applications, this paper presents novel designs for sensorless BLDC motor based on half-bridge driver circuit with buck modulator. For different applications, two specific back EMF detection methods: terminal voltage detection method and line voltage detection method, are proposed. The simulation results verified the validity of the proposed design for sensorless BLDC motor, and by comparisons we further pointed out different characteristics and possible applications of the two back EMF detection methods.
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