PM brushless drives with low-cost and low-resolution position sensors

PM brushless AC (BLAC) motor drive usually requires a high-resolution sensor, e.g. encoder, for rotor position detection. However, the encoder encounters problems such as high cost, low reliability, complicated installation and limited operation speed. To eliminate the encoder, a position estimation method using one or three low-cost and low-resolution Hall sensors is proposed for BLAC drive. A BLDC drive with a single Hall sensor is also presented. Both are experimentally investigated, with some particular problems being highlighted and solved.