Control circuit for electric vehicles

• US 4,691,148 A
• Filed: 09/25/1984
• Issued: 09/01/1987
• Est. Priority Date: 01/29/1981
• Status: Expired due to Term

• Current Assignee: Robin P. Nicholls, Rolland J. Savoie
• Original Assignee: Robin P. Nicholls, Rolland J. Savoie
• Inventors: Nicholls, Robin P., Savoie, Rolland J.
• Primary Examiner(s): Shoop, Jr., William M.
• Assistant Examiner(s): Ro, Bentsu
• Application Number:
  US06/653,851
• Time in Patent Office: 1,071 Days
• Field of Search: 318/9, 318/11, 318/12, 318/13, 318/14, 318/15, 318/139, 318/375, 318/376, 180/60, 180/65.1, 180/65.2, 180/65.4, 180/70.1, 180/75.1, 180/210, 180/211, 180/65.7
• US Class Current: 318/12
• CPC Class Codes: B60L 15/2045 for optimising the use of energy
• CPC Class Codes: B60L 2250/26 by pedal actuation
• CPC Class Codes: B60L 2260/30 Engine braking emulation
• CPC Class Codes: B60L 50/52 characterised by DC-motors
• CPC Class Codes: B60L 7/003 Dynamic electric braking by short circuiting the motor
• CPC Class Codes: B60L 7/12 for vehicles propelled by dc motors
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility

Abstract

The foot-operated accelerator develops digital signals progressively larger in number as the accelerator is moved through its range from a rest position to full speed. A variable transmission has a sensor that generates digital signals progressively larger in number as the transmission is shifted from a low gear ratio to a high gear ratio. For starting the vehicle, the accelerator lower digital signals cause successive connection of a plurality of batteries in series until the full operating battery voltage is applied to the motor. Thereafter, the motor operates at a constant voltage and vehicle speed is varied by varying the gear ratio of the transmission. This is achieved by a digital comparator that compares the accelerator numbers with the transmission numbers, and a lower accelerator number causes the transmission to shift to a lower gear ratio, and a higher accelerator number causes the transmission to shift to a higher gear ratio until equilibrium is reached in each case. The motor is protected from excessive current and excessive rpm by varying the gear ratio. Regenerative braking is utilized on both coasting and manual application of the brakes.

Claims

1. A control system for a vehicle controlled by an operator-movable accelerator movable through a range of distance from a rest position to a full power position, said vehicle being driven by a rotary electric motor through a variable transmission variable from a high gear ratio to a low gear ratio, said vehicle having a plurality of batteries, comprising:

(a) accelerator means for generating digital signals of progressive numbers dependent upon the position of the accelerator in its range;

(b) transmission means for generating digital signals of progressive numbers dependent upon the gear ratio of the transmission;

(c) a transmission actuator for changing the transmission to a higher or lower gear ratio;

(d) a comparator connected to the actuator and to the accelerator means and the transmission means to compare the signals from the accelerator means and the transmission means to operate the transmission actuator to a higher gear ratio when the accelerator number exceeds the transmission number and to operate the transmission actuator to a lower gear ratio when the transmission number exceeds the accelerator number,

(e) and switching means responsive to positions of said accelerator for successively connecting said batteries in series to the motor to obtain a higher voltage as the accelerator is moved toward a greater power position, said transmission numbers being more than the accelerator numbers until at least some of said batteries are connected in series to the motor.

2. A control system as set forth in claim 1 wherein there is added, for the protection of the motor:

(f) means for generating an electrical signal upon the motor current amperage reaching a maximum amperage reference;

(g) and a switch responsive to the maximum amperage signal to operate the transmission actuator to a higher gear ratio.

3. A control system as set forth in claim 1 wherein there is added, for protection of the electric motor:

(f) means for generating an electrical signal upon the motor reaching a maximum rpm reference;

(g) and a switch responsive to the maximum rpm signal to operate the transmission actuator to a higher gear ratio.

4. A control system for a vehicle controlled by an operator-movable accelerator movable through a range of distance from a rest position to a full power position, said vehicle being driven by a rotary electric motor through a variable transmission variable from a high gear ratio to a low gear ratio, said vehicle having a source of current, including a plurality of batteries, comprising:

(a) accelerator means for generating digital signals of progressive numbers dependent upon the position of the accelerator in its range;

(b) transmission means for generating digital signals of progressive numbers dependent upon the gear ratio of the transmission;

(c) a transmission actuator for changing the transmission to a higher or lower gear ratio;

(d) and a comparator connected to the actuator and connected to the accelerator means and the transmission means to compare the signals from the accelerator means and the transmission means to operate the transmission actuator to a higher gear ratio when the accelerator number exceeds the transmission number and to operate the transmission actuator to a lower gear ratio when the transmission number exceeds the accelerator number;

(e) relay switching means for successively connecting the batteries in series to obtain a higher voltage as the accelerator of the vehicle is moved toward a greater power demand; and

(g) a time delay in said switching means to obtain a minimum time of connecting each of the batteries, said delay being at least the time of relay operation.

5. A control system for a vehicle controlled by an operator-movable accelerator movable through a range of distance from a rest position to a full-power position and controlled further by an operator-movable brake, said vehicle being driven by a rotary electric motor also capable of generating electricity when mechanically driven, said motor being connected to a variable transmission variable from a high gear ratio to a low gear ratio, said vehicle having a source of current, comprising:

(a) accelerator means for generating digital signals of progressive numbers dependent upon the position of the accelerator in its range;

(b) transmission means for generating digital signals of progressive numbers dependent upon the gear ratio of the transmission;

(c) a transmission actuator for changing the transmission to a higher or lower gear ratio;

(d) a comparator connected to the actuator and to the accelerator means and the transmission means to compare the signals from the accelerator means and the transmission means to operate the transmission actuator to a lower gear ratio when the transmission number exceeds the accelerator number;

(e) means for sensing the voltage of the motor when acting as a generator;

(f) and a switch that is normally open at low accelerator numbers connected to the current source and the motor and operated by the voltage-sensing means and which closes when the generator voltage exceeds the voltage of the current source to thereby create regenerative braking.

6. A control system as set forth in claim 5 wherein there is added:

(g) a regenerative current sensor and;

(h) means connected to the sensor and to the transmission actuator and responsive to a sensed current reference to thereby vary the motor rpm to obtain a selected regenerative current.

7. A control system as set forth in claim 6 wherein the regenerative current sensor is provided with a first current reference about which the transmission is shifted to maintain the regeneration current at this reference and is provided with a second different current reference operative only when the brake is actuated and about which the transmission is shifted to obtain a regeneration current at this second current reference.

8. A control system for a vehicle controlled by an operator-movable accelerator movable through a range of distance from a rest position to a full-power position and controlled further by an operator-movable brake, said vehicle being driven by a rotary electric motor, said motor also being capable of generating electricity when mechanically driven, said motor being connected to a variable transmission variable from a high gear ratio to a low gear ratio, said vehicle having a source of current, comprising:

(a) a normally open battery switch closed by manually advancing the accelerator to connect the current source to the motor when the accelerator is advanced past its rest position, and which opens when the accelerator is released;

(b) brake switch operated by the brake to operate the battery switch to connect the current source to the motor when the brake is operated;

(c) and a generator voltage sensor interposed between the brake switch and the battery switch to prevent closing of the battery switch except when the generator voltage exceeds the voltage of the current source and to render the brake switch inoperable when the generated voltage of the motor is less than the voltage of the current source;

(d) means for varying the gear ratio of the transmission;

(e) and a regenerative current sensor connected to the means for varying the gear ratio, to thereby vary the motor rpm to obtain a selected range of regenerative current.

9. A control system for a vehicle controlled by an operator-movable accelerator movable through a range of distance from a rest position to a full-power position and controlled further by an operator-movable brake, said vehicle being driven by a rotary electric motor-generator, said motor-generator also being capable of generating electricity when mechanically driven, said motor-generator being connected to a variable transmission variable from a high gear ratio to a low gear ratio, said vehicle having a source of current comprising:

(a) a normally open battery switch closed by manually advancing the accelerator to connect the current source to the motor-generator when the accelerator is advanced past its rest position and which opens when the accelerator is released;

(b) and a generator voltage sensor connected to the motor-generator and the battery switch to close the battery switch when the voltage of the motor-generator exceeds the voltage of the source of current, to thereby obtain regenerative braking when the operator lets up on the accelerator without applying the brakes;

(c) an actuator for the variable transmission to change the gear ratio;

(d) and a generator current sensor having a reference connected to the actuator to decrease the gear ratio of the transmission when the current is less than a reference and to increase the gear ratio when the current is greater than the reference.

10. A control system for a vehicle controlled by an operator-movable accelerator movable through a range of distance from a rest position to a full power position, said vehicle being driven by a rotary electric motor through a variable transmission variable from a high gear ratio to a low gear ratio, said vehicle having a plurality of batteries, comprising:

(a) accelerator means for generating signals of progressive quantity starting at low quantity dependent upon the position of the accelerator in its range;

(b) transmission means for generating signals of progressive quantity above said low quantity dependent upon the gear ratio of the transmission;

(c) a transmission actuator for changing the transmission to a higher or lower gear ratio;

(d) and a comparator connected to the actuator and to the accelerator means and the transmission means to compare the signals from the accelerator means and the transmission means to operate the transmission actuator to a higher gear when the accelerator signal is greater than the transmission signal and the operate the transmission actuator to a lower gear ratio when the transmission quantity exceeds the accelerator quantity;

(e) and switching means responsive to accelerator position for successively connecting said batteries in series to said motor to obtain a higher voltage as the accelerator is moved toward a greater power position, whereby signal matching takes place after some of said batteries are connected in series to the motor.

11. A servo loop for controlling a variable speed transmission on an electric vehicle having an accelerator and an electric motor and a variable speed transmission, comprising:

(a) means for producing a signal progressive in quantity as the accelerator is advanced;

(b) means for producing a signal progressive in quantity as the transmission varies from a low-speed ratio to a high-speed ratio;

(c) means for comparing the two signals;

(d) and an actuator controlled by the comparing means for shifting the transmission to a higher gear ratio if the accelerator signal is greater and for shifting to a lower gear ratio if the transmission signal is greater,

said transmission signal constituting a feedback in the servo loop of comparing means, actuator, transmission, accelerator signal, and transmission signal;

(e) a plurality of batteries connected to said motor

(f) and switching means responsive to accelerator advance for successively connecting said batteries in series to attain an operational motor voltage.

12. A control system for a vehicle controlled by an operator-movable accelerator movable through a range of distance from a rest position to a full-power position, said vehicle being driven by a rotary electric motor-generator through a variable transmission variable from a high gear ratio to a low gear ratio, comprising:

(a) a plurality of batteries;

(b) means for successively connecting the batteries in series to the electric motor-generator as the accelerator is moved from a rest position to a full power position;

(c) accelerator means for generating digital signals of progressive numbers dependent upon the position of the accelerator in its range;

(d) transmission means for generating digital signals of progressive numbers dependent upon the gear ratio of the transmission;

(e) a transmission actuator for changing the transmission to a higher or lower gear ratio;

(f) and a comparator connected to the transmission means, to the accelerator means and to the transmission actuator to operate said transmission actuator to a higher gear ratio when the accelerator number exceeds the transmission number and to operate the transmission actuator to a lower gear ratio when the transmission number exceeds the accelerator number, whereby said motor-generator acts to brake the vehicle by regenerative current when the accelerator is in a position of low demand and the vehicle is moving faster than is normally associated with said accelerator demand.