| 摘要 |
PURPOSE:To generate a trapezoidal wave with no stoppage of the driving current by a method wherein the voltage drop due to the driving current is subtracted from the sum of the counter electromotive force generated in driving coils and the voltage drop due to the driving current and a waveform of the driving current is calculated based on the subtraction result and then a phase is switched. CONSTITUTION:An MPU1 makes a control of a trapezoidal wave by means of driving currents i1-i3. When a motor rotates, the counter electromotive force is generated in three driving coils 2a-2c and the voltage drop is also generated due to coil resistances of the driving currents i1-i3. With the counter electromotive force and the voltage drop input into a group of buffer circuits 5, the outputs of the group of buffer circuits 5 are voltage signals Vm1-Vm3. The detected voltages Vm1-Vm3 are input into a group of A/D's 6 and then the value data DV1-DV3 are obtained. In a group of subtraction circuits 7, driving value data DD1-DD3 are subtracted from the detected value data DV1-DV3. Then, signals e1-e3 which are proportional only to the counter electromotive force are obtained. By this method, the optimum slope of trapezoidal waves of the driving signals can be obtained. |
