| 摘要 |
An electric vehicle traction motor control circuit includes separate armature and field current controls. The armature control includes a difference amplifier connected to compare a current demand signal with an actual current signal from a transducer and a switching circuit controlled by this difference amplifier. The field control includes a second difference amplifier which operates to weaken the field current in either of two eventualities. In motoring the second difference amplifier receives its input via a start up circuit which connects the output of the first difference amplifier to the input of the second difference amplifier when the switching means has been in a first state for more than a predetermined time. In this case the field is weakened in accordance with the short fall of the output of the first difference amplifier below a first reference level. In braking the second difference amplifier receives its input via a further difference amplifier and a diode gate to weaken the field current in accordance with the excess of armature current over a second reference level. |
