| 摘要 |
PURPOSE:To save electric power by obtaining a logic sum of a voltage proportional to the current flowed to each motor coil, and controlling the drive current in response to this value. CONSTITUTION:Transistors Q1b-Q3b connected in series with stator coils L1- L3 are sequentially switched by a 3-phase pulse signal outputted from a pulse generator PG. At this time the logic sum of the voltages applied to the coils L1-L3, i.e., the potential in response to the magnitude of a load can be obtained at the common connection point A of diodes D1, D2. The potential at this point A is supplied through mirror circuits M1, M2, to transistors Q1a-Q3a of the front stage of a Darlington connection. In this manner, a suitable drive current can be always applied in response to the magnitude of the load, thereby saving the electric power. |
