| 摘要 |
A motor driving system includes an offset value learning part, which learns offset values of current sensors, when all switching elements are in off-states and a motor driving circuit is in an off-state, in which the motor driving circuit generates no motor driving current. The offset value learning part includes a first learning part and a second learning part. The first learning part learns the offset value of the current sensor of each phase at an arbitrary motor rotation angle, when an induced motor voltage of a three-phase motor is smaller than an input voltage of the motor driving circuit. The second learning part sequentially learns the offset value of the current sensor of the phase, a phase voltage value of which varying with the motor rotation angle is intermediate, when the induced motor voltage is equal to or larger than the input voltage. |
| 主权项 |
1. A motor driving system comprising:
a DC power source; a motor of three phases connected to the DC power source for generating a rotary force when powered electrically; a motor driving circuit including a plurality of switching elements and a plurality of rectifying elements connected in parallel to the switching elements, respectively, for generating motor driving currents from the DC power source for driving the motor by switching operations of the switching elements, current sensors provided in at least two phases among the three phases of the motor for detecting the motor driving currents; and a control circuit for controlling the motor driving circuit in accordance with detection currents detected by the current sensors, wherein the control circuit includes an offset value learning part for learning offset values of the current sensors when all the switching elements are turned off and the motor driving circuit is in an off-state, in which no motor driving current is generated, the offset learning part includes a first offset learning part, which learns the offset value of the current sensor of each phase at an arbitrary motor rotation angle in a case of Vmot<Vin, Vmot being an induced motor voltage of the motor and Vin being an input voltage of the motor driving circuit, and the offset learning part includes a second offset learning part, which learns sequentially the offset value of the current sensor provided in a subject phase, which is one of the three phases and has a phase voltage value is intermediate in a case of Vmot≧Vin. |
