| 摘要 |
A reversing d.c. shunt motor uses field reversal to obtain reversed rotation. The inductive field winding (L) lies in the diagonal of a four transistor (Q1-Q4) bridge fed from a d.c. supply (P). Current flow, and hence field polarity, depends on which pair of transistors is conducting. Each transistor is bridged by a flywheel diode (D1-D4). Rapid field reversal is obtained by placing a capacitor (C) in the d.c. supply to the bridge, the capacitor and field inductance forming a series resonant circuit. When the transistors switch off, stored energy is transferred from the field to the capacitor where it is available again to boost the current when the opposite bridge arms subsequently turn on. |
