| 摘要 |
<p>PURPOSE:To prevent the malfunction of an overvoltage relay immediately after a connection is transferred to series one from parallel one by discriminating the conditions of electric-car line voltage and armature currents at the end period of a parallel-step brake. CONSTITUTION:When shun field currents IF exceed parallel control limit shunt field currents IF2 or more under the state in which main motors 12, 13 are connected in parallel and a brake is controlled, parallel-series transition is conducted when armature currents Ia are half or less of the predetermined value I3 of currents immediately after armature currents Ia enter a series connec tion or when electric-car voltage VL reaches an allowable upper-limit value VL0 or less when armature currents Ia are half or more of I3. When electric-car voltage VL reaches the allowable upper-limit value VL0 or more, on the other hand, a regenerative brake is disconnected. Shunt field currents are weakened up to the half value of motor voltage, and parallel-series transition is conducted.</p> |
