Electrically propelled vehicle
First Claim
1. A propulsion system for an electrical vehicle comprising in combination, a propulsion battery, a separately excited d.c. motor for propelling the vehicle, said motor having an armature winding and a field winding, a proportional controller, control signal producing means responsive to a command signal and a signal indicative of a motor operating condition for increasing or decreasing the operating level of the controller to drive the motor in accordance with the command signal, switching means for establishing a motor circuit including an armature control mode and a field control mode, said switching means including means for interposing the controller between the battery and the armature and means for coupling the field to the battery in said armature control mode, said switching means further including means for interposing the controller between the battery and the field and means for coupling the armature to the battery in said field control mode, means for detecting the maximum operating level of the controller, and means responsive to said detecting means and said control signal producing means and operative upon said switching means for causing said switching means to switch from one of said modes to the other of said modes when said controller is at maximum operating level and said control signal producing means requires a further increase in said operating level, whereby said controller is safely switched between modes to control the motor in respective armature and field control modes.
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Accused Products
Abstract
A propulsion system for an electrical vehicle including a linear proportional controller operable in a plurality of modes for operating a d.c. drive motor via power derived from a propulsion battery. Low speed operation is achieved in an armature control mode wherein the controller is interposed between the propulsion battery and the motor armature while the motor field is coupled directly across the battery. High speeds are attained in a field control mode wherein the controller is interposed between the battery and motor field while the armature is coupled directly across the propulsion battery, thereby eliminating controller losses from the high current armature circuit. Switching between modes is achieved in a manner which minimizes stress on the switching elements. The controller is also adapted to operate in a charger mode wherein unregulated d.c. power is fed to the controller which functions to regulate the charge provided to the battery. Overall efficiency is increased by use of a dual chopper as a power modulator element. The circuit further includes protection means for controlling or preventing operation under conditions wherein circuit elements might be damaged.
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Citations
26 Claims
- 1. A propulsion system for an electrical vehicle comprising in combination, a propulsion battery, a separately excited d.c. motor for propelling the vehicle, said motor having an armature winding and a field winding, a proportional controller, control signal producing means responsive to a command signal and a signal indicative of a motor operating condition for increasing or decreasing the operating level of the controller to drive the motor in accordance with the command signal, switching means for establishing a motor circuit including an armature control mode and a field control mode, said switching means including means for interposing the controller between the battery and the armature and means for coupling the field to the battery in said armature control mode, said switching means further including means for interposing the controller between the battery and the field and means for coupling the armature to the battery in said field control mode, means for detecting the maximum operating level of the controller, and means responsive to said detecting means and said control signal producing means and operative upon said switching means for causing said switching means to switch from one of said modes to the other of said modes when said controller is at maximum operating level and said control signal producing means requires a further increase in said operating level, whereby said controller is safely switched between modes to control the motor in respective armature and field control modes.
- 6. A propulsion system for an electrical vehicle comprising in combination, a propulsion battery for providing operating power, a separately excited d.c. drive motor for propelling the vehicle, a variable duty cycle controller having an input and an output, said input being coupled to the propulsion battery, the drive motor having an armature winding and a field winding, switch means for selectively coupling the controller output and the battery to the motor armature and motor field, said switch means having an armature control mode wherein the battery is coupled across the field winding and the output of the controller is coupled to the armature winding, said switch means having a field control mode wherein the battery is coupled across the armature winding and the controller output is coupled to the field winding, mode control means for establishing the respective modes of the switch means, duty cycle control means for varying the operating duty cycle of the controller thereby to control the motor speed, and means responsive to the operating duty cycle of the controller for energizing the mode control means to switch from one of said modes to the other of said modes when said operating duty cycle is at a maximum.
- 10. A propulsion system for an electrical vehicle comprising in combination a propulsion battery for providing power to the vehicle, a d.c. motor for propelling the vehicle, said motor having an armature winding and a field winding, a variable duty cycle power controller having an input coupled to the propulsion battery and an output, accelerator means for producing a demand signal related to a demanded armature current, feedback means for producing a feedback signal related to the actual armature current, means for comparing the feedback signal and the demand signal to produce a control signal, means for producing an inverted control signal, a duty cycle control for setting the duty cycle of the converter, mode selector means for establishing an armature control mode and a field control mode, switching means responsive to the mode selector means for coupling the armature to the output of the controller and coupling the field to the battery in the armature control mode and for coupling the armature to the battery and coupling the field to the controller in the field control mode, means responsive to the mode control means for coupling the control signal to the duty cycle control in the armature mode so that the duty cycle of the controller increases with increasing levels of control signal, means coupling the inverted control signal to the duty cycle control in the field control means so that the duty cycle of the converter is decreased with increasing levels of control signal, first mode switching means responsive to the duty cycle control and to the control signal for causing said mode control means to switch from armature control to field control when the duty cycle is at maximum and the control signal indicates that the actual armature current is less than the demanded armature current, whereby mode switching is accomplished with minimum stress on the switching elements.
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26. A propulsion system for a battery powered electrical vehicle comprising in combination, a separately excited d.c. motor for propelling the vehicle, said motor having an armature winding and a field winding, a proportional controller, control signal producing means responsive to a command signal and a signal indicative of a motor operating condition for increasing or decreasing the operating level of the controller to drive the motor in accordance with the command signal, switching means for establishing an armature control mode and a field control mode for said motor, said switching means including means for interposing the controller between the power battery and armature and means for coupling the field to the battery in said armature control mode, said switching means further including means for interposing the controller between said battery and the field and means for coupling the armature to said battery in said field control mode, means for detecting the maximum operating level of the controller, and means responsive to said detecting means and said control signal producing means and operative upon said switching means for causing said switching means to switch from one of said modes to the other of said modes when said controller is at maximum operating level and said control signal producing means requires a further increase in said operating level, whereby said controller is safely switched between modes to power the motor in respective armature and field control modes.
Specification