Patent ID: 8183803

Claim:
A brushless DC motor control system comprising an inverting circuit for outputting operational power supply to a three-phase motor and a current sensor for detecting working current of the three-phase motor, in which the inverting circuit comprises switch tubes Q 1 , Q 3 and Q 5 connected with an upper bridge arm, switch tubes Q 4 , Q 6 and Q 2 connected with a lower bridge arm and freewheel diodes D 1 , D 2 , D 3 , D 4 , D 5 and D 6 cooperating with each of the above switch tubes, respectively; wherein the current sensor comprises two sampling coils L 1 and L 2 that have the same number of turns and are wound around the same iron core, in which a sensing element that outputs current sensing result according to a magnetic flux change of the iron core is mounted on the iron core; cathodes of the freewheel diodes D 1 , D 3 and D 5 of the switch tubes Q 1 , Q 3 and Q 5 are independent of input terminals of their respective switch tubes and connected in parallel to a like terminal of the sampling coil L 1 ; and the sampling coil L 1 is connected in series in the upper bridge arm, its like terminal being connected with an anode of a DC power supply; and anodes of the freewheel diodes D 4 , D 6 and D 2 of the switch tubes Q 4 , Q 6 and Q 2 are independent of output terminals of their respective switch tubes and connected in parallel to an unlike terminal of the sampling coil L 2 , a like terminal of the sampling coil L 2 being connected with the lower bridge arm.