Traction motor drive system

• US 6,331,365 B1
• Filed: 11/12/1998
• Issued: 12/18/2001
• Est. Priority Date: 11/12/1998
• Status: Expired due to Term

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: King, Robert Dean
• Primary Examiner(s): KALAFUT, STEPHEN J
• Application Number:
  US09/190,069
• Time in Patent Office: 1,132 Days
• Field of Search: 429/9, 320/103, 320/126
• US Class Current: 429/9
• CPC Class Codes: B60L 2210/14 Boost converters
• CPC Class Codes: B60L 2210/20 AC to AC converters
• CPC Class Codes: B60L 2220/18 Reluctance machines
• CPC Class Codes: B60L 2240/545 Temperature
• CPC Class Codes: B60L 2240/547 Voltage
• CPC Class Codes: B60L 2240/549 Current
• CPC Class Codes: B60L 50/51 characterised by AC-motors
• 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 power system for an electric motor drive such as may be used in an electrically propelled vehicle incorporates the combination of a high power density battery and a high energy density battery to provide an optimal combination of high energy and high power, i.e., a hybrid battery system. The hybrid battery system in one form includes components which prevent electrical recharge energy from being applied to the high energy density battery while capturing regenerative energy in the high power density battery so as to increase an electric vehicle'"'"'s range for a given amount of stored energy. A dynamic retarding function for absorbing electrical regenerative energy is used during significant vehicle deceleration and while holding speed on down-hill grades, to minimize mechanical brake wear and limit excessive voltage on the battery and power electronic control devices. The high energy density battery coupled in circuit with a boost converter, a high power density battery, a dynamic retarder, and an AC motor drive circuit. The hybrid battery system is controlled by a hybrid power source controller which receives signals from a vehicle system controller using current and voltage sensors to provide feedback parameters for the closed-loop hybrid battery control functions.

Claims

1. A hybrid battery arrangement for an electrically powered system in which battery loading is subject to intermittent high power loading, the system including a hybrid battery coupled to supply electric power via a DC link to a load and a control system for controlling application of power to the load, the hybrid battery arrangement comprising:

a first battery coupled to the DC link;

a second battery coupled to the DC link, the first battery having higher energy and lower power densities than the second battery; and

a boost converter, including a unidirectional conductor, coupled in circuit between the first battery and the second battery for selectively boosting the voltage from the first battery to a level sufficient to force current through the unidirectional coupler to the second battery.

2. The hybrid battery arrangement of claim 1 wherein the first battery includes an assembly of first batteries and the boost converter includes a plurality of boost converters, each of the boost converters being coupled between a respective one of the first batteries and the second battery.

3. The hybrid battery arrangement of claim 1 further including a dynamic retarder coupled in circuit between the second battery and the first battery for controlling voltage of the DC link to within selected levels of the nominal operating voltage of the second battery.

4. The hybrid battery arrangement of claim 3 wherein the first battery comprises at least one mechanically rechargeable battery, and wherein the unidirectional coupler prevents current from flowing from the second battery to the first battery.

5. The hybrid battery arrangement of claim 3 wherein the boost circuit comprises:

an inductor coupled between the first battery and the unidirectional conductor;

a first switch coupled at a junction of the inductor and the unidirectional conductor; and

a control system for selectively gating the first switch into conduction for establishing a current through the inductor and for gating the first switch out of conduction whereby the inductor current is forced through the unidirectional conductor.

6. The hybrid battery arrangement of claim 3 wherein the dynamic retarder comprises the serial combination of a power dissipating resistance and a second switch with the control system operable to selectively gate the second switch into and out of conduction in a manner to control the voltage across the second battery.

7. The hybrid battery arrangement of claim 1 wherein the first battery comprises an electrically rechargeable battery.

8. The hybrid battery arrangement of claim 7 wherein the first battery comprises a sodium-nickel-chloride battery, a lithium-ion battery, or a nickel-metal-hydride battery.

9. The hybrid battery of claim 7 further including a switch connected in parallel with the unidirectional conductor for selectively permitting current transfer to the first battery.

10. The hybrid battery of claim 1 further including a diode serially connected between the first battery and the boost converter, the diode being poled to block current from the boost converter to the first battery.

11. The hybrid battery arrangement of claim 10 wherein the first battery comprises an assembly of mechanically rechargeable batteries,

the diode includes a plurality of diodes,

and the boost converter includes a plurality of boost converters,

each of the mechanically rechargeable batteries being isolated from others of the mechanically rechargeable batteries by a corresponding one of the diodes, each of the diodes connecting an associated one of the mechanically rechargeable batteries to a respective one of the boost converters, and each one of the boost converters being coupled to the second battery.

12. The hybrid battery of claim 10 further including a switch connected in parallel with the unidirectional conductor for selectively permitting current in a reverse direction through the boost converter, the system including auxiliary loading devices connected in circuit between the diode and the boost converter for utilizing the reverse current.

20. The hybrid battery arrangement of claim 1 wherein the first battery comprises a zinc-air battery and the second battery comprises a nickel-cadmium battery.

13. A hybrid battery power system for an AC electric motor, the system comprising:

a direct current (DC) link;

an inverter coupled to the DC link; and

a first battery and a second battery, each battery being coupled in circuit with the DC link such that power is suppliable to the inverter conjointly from the batteries, the first battery having higher energy and lower power densities than the second battery, the DC link being arranged such that regenerative energy is suppliable to the second battery and isolatable from the first battery.

14. The hybrid battery power system of claim 13 further including a diode connected in the DC link between the first battery and the second battery, the diode being poled to prevent current flow from the second battery to the first battery.

15. The hybrid battery power system of claim 14 further including a voltage boost circuit connected in circuit with the first battery for selectively enabling transfer of power from the first battery to the second battery.

16. The hybrid battery power system of claim 15 wherein the voltage boost circuit comprises the series combination of an inductor and a controllable electronic switch, the inductor being serially connected between the first battery and the diode, the switch being connected to a junction mediate the inductor and the diode and arranged to place the inductor in a short-circuit position across the first battery for establishing a current therethrough when the switch is conducting, and a control system coupled to the switch for selectively gating the switch into and out of conduction for boosting current through the diode to the second battery.

17. The hybrid battery power system of claim 16 and including a dynamic retarder coupled to the DC link at the second battery for controlling the voltage on the DC link.

18. The hybrid battery power system of claim 17 wherein the dynamic retarder comprises the series combination of a power resistor and a second electronically controllable switch, the second switch being selectively gated into and out of conduction so as to vary the effective resistance appearing on the DC link for limiting the magnitude of voltage on the link.

19. The hybrid battery power system of claim 17 further including at least one electrically powered accessory device coupled to the DC link for capturing regenerative power.

21. The hybrid power system of claim 13 wherein the first battery comprises a zinc-air battery and the second battery comprises a nickel-cadmium battery.

22. A hybrid battery arrangement for an electrically powered system in which battery loading is subject to intermittent high power loading, the system including a hybrid battery coupled to supply electric power via a DC link to a load and a control system for controlling application of power to the load, the hybrid battery arrangement comprising:

a mechanically rechargeable battery coupled to the DC link;

an electrically rechargeable battery coupled to the DC link; and

a boost converter, including a unidirectional conductor, coupled in circuit between the mechanically rechargeable battery and the electrically rechargeable battery for selectively boosting the voltage from the mechanically rechargeable battery.