| 摘要 |
<P>PROBLEM TO BE SOLVED: To eliminate the inconvenience that a circuit scale is increased since a calculating circuit for calculating a prescribed electric angle is required as a result of the doubled energization state from six states to twelve states in order to prevent a reverse flow current at the time of switching a phase of a brushless motor having a three-phase winding of star connection compared with when no reverse flow current is taken into account. <P>SOLUTION: A switching element, which is intermittently turned off, in two switching elements to become On-timing is continuously turned on by masking a Peak detecting signal for a first prescribed period of time after the switching of two-phase energization at the time of switching the phase. Consequently, the current flowing before switching the phase is looped in a switching circuit 3 until it is attenuated. The reverse flow from GND to a motor power supply 2 is prevented. A circuit is simplified by using a circuit for setting a simple masking time in the current detection type PWM control. Rotational speed control can be constantly executed even with one-side chopping. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
