Low cost electronic ultracapacitor interface technique to provide load leveling of a battery for pulsed load or motor traction drive applications

• US 5,723,956 A
• Filed: 05/28/1996
• Issued: 03/03/1998
• Est. Priority Date: 05/28/1996
• Status: Expired due to Term

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: King, Robert Dean, DeDoncker, Rik Wivina Anna Adelson
• Primary Examiner(s): Ro, Bentsu
• Application Number:
  US08/654,476
• Time in Patent Office: 644 Days
• Field of Search: 318/139, 318/440, 318/442, 318/500, 318/504, 307/43-46, 307/72, 307/74, 307/75, 323/220, 323/223, 323/224, 323/225, 323/229, 323/230, 323/233, 323/265, 323/282
• US Class Current: 318/139
• CPC Class Codes: B60L 2210/20 AC to AC converters
• CPC Class Codes: B60L 50/40 using propulsion power supplied by capacitors
• CPC Class Codes: H02J 7/34 Parallel operation in networks using both storage and other dc sources, e.g. providing buffering H02J7/14 takes precedence
• CPC Class Codes: H02M 1/14 Arrangements for reducing ripples from dc input or output
• 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

A battery load leveling arrangement for an electrically powered system in which battery loading is subject to intermittent high current loading utilizes a passive energy storage device and a diode connected in series with the storage device to conduct current from the storage device to the load when current demand forces a drop in battery voltage. A current limiting circuit is connected in parallel with the diode for recharging the passive energy storage device. The current limiting circuit functions to limit the average magnitude of recharge current supplied to the storage device. Various forms of current limiting circuits are disclosed, including a PTC resistor coupled in parallel with a fixed resistor. The current limit circuit may also include an SCR for switching regenerative braking current to the device when the system is connected to power an electric motor.

Claims

1. A battery load leveling arrangement for an electrically powered system in which battery loading is subject to intermittent high current loading, the system including a battery, a load and a system controller coupled to the battery and load for controlling application of power to the load, the improvement comprising:

a passive energy storage device;

unidirectional conducting means coupled in series electrical circuit with said passive energy storage device and poled to conduct current from said storage device to the load, said series electrical circuit being coupled in parallel electrical circuit with the battery whereby said passive energy storage device provides current to the load and the battery when battery terminal voltage is less than voltage on said passive energy storage device by an amount at least equal to a voltage drop across said unidirectional. conducting means; and

current limiting means connected in electrical parallel circuit with said unidirectional conducting means for providing an electrical current path for recharge current to said passive energy storage device and for limiting the average magnitude of recharge current to said device, said current limiting means comprising a current limiting switch in electrical parallel circuit arrangement with a resistor, said current limiting switch being operable to switch to a high impedance condition in response to recharge current above a selected average magnitude so as to divert said recharge current through said resistor.

2. The battery load leveling arrangement of claim 1 wherein said current limiting switch comprises a positive temperature coefficient resistance.

3. The battery load leveling arrangement of claim 1 wherein said passive energy storage device comprises an ultracapacitor.

4. The battery load leveling arrangement of claim 1 wherein said current limiting switch comprises a metal-oxide-semiconductor field effect transistor connected in a source follower configuration.

5. The battery load leveling arrangement of claim 1 wherein said current limiting switch comprises a bipolar transistor and current sensing means coupled to modulate base drive current of said transistor in a manner to limit current through said transistor.

6. The battery load leveling arrangement of claim 1 wherein said current limiting switch comprises an insulated gate bipolar transistor (IGBT), a current sensing pilot resistor coupled to an emitter terminal of said IGBT, and a gate drive circuit responsive to voltage on said pilot resistor for providing a current signal to modulate base drive current in said IGBT in a manner to limit current through said IGBT.

7. The battery load leveling arrangement of claim 1 and including a controllable switching circuit coupled in parallel electrical circuit with said current limiting means, said controllable switching circuit being operable to provide a low resistance recharge current path to said passive energy storage device.

8. The battery load leveling arrangement of claim 7 wherein said load comprises an electrical motor operative in a propulsion and a regenerative braking mode, said controllable switching circuit being operable in said regenerative braking mode for transferring regenerative current from said motor to said energy storage device.

9. The battery load leveling arrangement of claim 8 wherein said controllable switching circuit comprises a silicon controlled rectifier.

10. A battery load leveling system for use in a control system for an electric traction motor, the control system including a battery, an electronic power regulator for regulating power applied to the motor in response to a power command signal, said power regulator being coupled to receive power from said battery, the improvement comprising:

an ultracapacitor;

a diode coupled in series electrical circuit with said ultracapacitor, the series combination of the diode and ultracapacitor being coupled in parallel electrical circuit with said battery, said diode being poled to block current from the battery to the ultracapacitor; and

a current limiting switch coupled in parallel electrical circuit with said diode and comprising a positive temperature coefficient (PTC) resistance and a fixed resistor coupled in parallel electrical circuit with said PTC resistance, said current limiting switch having a relatively low resistance for relatively low magnitudes of current and having a relatively high resistance for relatively high magnitudes of current so as to facilitate recharging of the ultracapacitor with relatively low current through said current limiting switch.

11. A battery load leveling system for receiving power from a battery, comprising:

an ultracapacitor;

a diode coupled in series electrical circuit with said ultracapacitor, the series combination of the diode and ultracapacitor being coupled in parallel electrical circuit with said battery, said diode being poled to block current from the battery to the ultracapacitor;

a current limiting switch coupled in parallel electrical circuit with said diode, said current limiting switch having a relatively low resistance for relatively low magnitudes of current and having a relatively high resistance for relatively high magnitudes of current so as to facilitate recharging of the ultracapacitor with relatively low current through said current limiting switch; and

a control system for an electric traction motor and a controllable switching circuit coupled in parallel electrical circuit with said current limiting switch, said control system being responsive to power or torque commends and further controlling impedance of said controllable switching circuit so as to provide a low resistance recharge current path to the ultracapacitor for battery load leveling.

12. The battery load leveling system of claim 11 wherein the current limiting switch comprises a positive temperature coefficient (PTC) resistance and a fixed resistor coupled in parallel electrical circuit with said PTC resistance.