Regenerative braking method
A neighborhood electrical vehicle (NEV), including provisions for improved deceleration during regenerative braking, in which the vehicle momentum is converted to electrical energy stored in a capacitor bank. The capacitor bank includes alternate configurations for charging or discharging of the capacitors.
1. A vehicle, comprising:
three wheels arranged as a tricycle and supporting a seat by a frame;
a brushless DC motor mechanically coupled to at least one of the wheels;
a rechargeable battery;
an capacitor;
an electronic controller in electrical communication with said capacitor, said battery, and said motor, said electronic controller being operable in at least two modes; and
a pair of pedals operatively connected to an electrical generator, said pedals being adapted and configured for a human operator to provide motive power to said generator, said generator being in electrical communication with said controller;
wherein in a first mode of operation said controller receives electrical power generated by said motor and provides the power to said capacitor, and in a second mode of operation said controller provides power from said capacitor to said battery.
2. The vehicle of claim 1 wherein said capacitor is an electric double-layer capacitor.
3. The vehicle of claim 1 which further comprises a braking sensor providing an electrical signal corresponding to an amount of braking desired by the human operator, wherein the signal is provided to said controller, said controller chops the power received from said motor in a duty cycle, and the duty cycle of the chopped power corresponds to the electrical signal.
4. The vehicle of claim 3 wherein the signal is a pulse-width modulated alternating signal.
5. The vehicle of claim 3 wherein said controller receives alternating electrical power from said motor, and the frequency of the alternating power is less than about 1000 hertz.
6. The vehicle of claim 1 wherein said capacitor has a capacity of more than about 40 farads.
7. The vehicle of claim 1 which further comprises a plurality of capacitors electrically connected in parallel.
8. The vehicle of claim 1 which further comprises a braking member movable over a range of positions by the human operator, wherein said controller provides power to said capacitor in relation to movement of said member within a first portion of the range.
9. The vehicle of claim 8 wherein said braking member is a hand control.
10. The vehicle of claim 8 which further comprises a friction braking assembly mechanically connected to at least one said wheel, said braking assembly being actuatable by said braking member.
11. The vehicle of claim 10 wherein said braking assembly is not actuated by movement of said member within the first portion of the range.
12. The vehicle of claim 1 wherein said controller has a third mode of operation in which said controller provides power from said battery to said motor.
13. A method for operating an electric vehicle, comprising:
providing a tricycle, a generator rotatable by a foot pedal, a braking lever movable over a range of positions, at least one ultracapacitor, and a seat, at least one of the wheels being coupled to an electric motor capable of driving the wheel and capable of generating electricity;
generating alternating current electricity by the motor in response to placement of the lever within the range;
slowing the vehicle by said generating by the motor;
generating electricity from the generator by rotation with the foot pedal; and
charging the ultracapacitor with electricity from said generating by the motor and from said generating from the generator.
14. The method of claim 13 which further comprises a plurality of ultracapacitors configured for parallel operation during said charging the ultracapacitors.
15. The method of claim 13 which further comprises electronically reconfiguring the ultracapacitors to series operation, and powering the motor with the reconfigured ultracapacitors.
16. The method of claim 13 wherein said providing includes a rechargeable battery, and which further comprises charging the battery with the charged ultracapacitor.
17. The method of claim 13 wherein the motor is an electrically commutated motor.
18. The method of claim 13 wherein the ultracapacitor is associated with an RC time constant and which further comprises rectifying the alternating current electricity, chopping the rectified electricity at a predetermined frequency, and establishing the predetermined frequency to be less than about four time constants.
19. The method of claim 13 which further comprises establishing a duty cycle corresponding to placement of the level within the range, wherein said charging corresponds to the duty cycle.
20. The vehicle of claim 1 wherein said pedals are foot pedals.
21. The vehicle of claim 1 wherein two of said wheels are rotate about a common axis in front of said seat.
22. The vehicle of claim 21 wherein said pedals are foot pedals located in front of the common axis.