| 摘要 |
PURPOSE:To obtain a simple driver of low cost and small size by measuring two phases of coil current through one current detector simultaneously and by operating according to a current commutation information. CONSTITUTION:A current detector 10 detects a current having passed through a core. In this case, Iu and the reversed polarity of Iv pass through the core simultaneously so that the sum of Iu and -Iv is detected and the detection ratio of Iu and Iv is 1 to -1. When the detection coefficient of the current detector is K(V/A), the output voltage V of the current detector is V=K(Iu-Iv). The brushless motor of rectangular wave drive has a commutation information and generates a continuous torque to rotate by successively switching a coil current according to the position of a rotor. Because the coil current flows according to the commutation information, the phase and direction for the current to flow in each commutation timing is already known. In any commutation timing, also, there is always one phase where the current becomes zero and the quantities of current flowing in other two phases are approximately equal to each other. |
