| 摘要 |
<p>An electric vehicle having a separately excited filed controlled direct current drive motor powered by a direct current power supply wherein field current is pulsewidth modulated in response to operator control and the vehicle operating parameters. An armature current demand signal which is dependent on a throttle setting compared with an actual armature current signal derived from an armature shunt and the difference is applied to a field current output amplifier which supplies current to the separately excited field to reduce the difference to zero. The armature current demand signal is responsive to the operator's control of the throttle in the electric vehicle. The drive motor of the electric vehicle or a regenerative mode for braking the electric vehicle and supplying energy to the power supply. The armature demand signal is also influenced by various operating conditions to improve operation of the electric vehicle. During vehicle operation a minimum pulse-width current signal is always applied to the separately excited field of the direct current drive motor to prevent overspeed and motor damage. To maintain smooth control of the electric vehicle, the armature current demand signal relative to a given throttle setting is shifted as a function of motor speed. Compensating means are provided to limit the variation of field excitation as a function of variation in battery voltages.</p> |
