Hybrid electric vehicle with reduced auxiliary power to batteries during regenerative braking

• US 5,910,722 A
• Filed: 03/20/1998
• Issued: 06/08/1999
• Est. Priority Date: 11/21/1997
• Status: Expired due to Term

• Current Assignee: BAE Systems Controls Incorporated (BAE Systems Plc)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Lyons, Arthur Paull, Grewe, Timothy Michael
• Primary Examiner(s): Tso, Edward H.
• Application Number:
  US09/044,669
• Time in Patent Office: 445 Days
• Field of Search: 320/104, 320/123, 320/FOR 155, 320/FOR 160, 320/FOR 171, 320/DIG 34, 180/65.1, 180/65.2, 180/65.3, 180/65.4, 180/69.5, 180/69.6, 322/2 R, 322/17, 322/39, 322/44, 322/45
• US Class Current: 320/104
• CPC Class Codes: B60K 6/46 Series type
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 10/26 for electrical energy, e.g. batteries or capacitors
• CPC Class Codes: B60W 20/00 Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• CPC Class Codes: B60W 20/13 in order to stay within battery power input or output limits; in order to prevent overcharging or battery depletion
• CPC Class Codes: B60W 2050/146 Display means
• CPC Class Codes: B60W 2510/244 Charge state
• CPC Class Codes: B60W 2510/246 Temperature
• CPC Class Codes: B64G 1/425 Power storage
• CPC Class Codes: B64G 1/428 Power distribution and management
• CPC Class Codes: Y02T 10/62 Hybrid vehicles
• CPC Class Codes: Y02T 10/7072 Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility
• CPC Class Codes: Y02T 90/40 Application of hydrogen technology to transportation, e.g. using fuel cells

Abstract

An electric vehicle is controlled to conform its operation to that of a conventional internal-combustion-engine powered vehicle. In some embodiments, the charging of the batteries by the auxiliary source of electricity and from dynamic braking is ramped in magnitude when the batteries lie in a state of charge between partial charge and full charge, with the magnitude of the charging being related to the relative state of charge of the battery. The deficiency between traction motor demand and the energy available from the auxiliary electrical source is provided from the batteries in an amount which depends upon the state of the batteries, so that the full amount of the deficiency is provided when the batteries are near full charge, and little or no energy is provided by the batteries when they are near a discharged condition. At charge states of the batteries between near-full-charge and near-full-discharge, the batteries supply an amount of energy which depends monotonically upon the charge state. Charging of the batteries from the auxiliary source is reduced during dynamic braking when the batteries are near full charge. Control of the amount of energy returned during dynamic braking may be performed by control of the transducing efficiency of the traction motor operated as a generator.

Claims

1. A method for operating a hybrid electric vehicle which derives at least some of its tractive effort from electric batteries, comprising the steps of:

providing energy from a traction battery to a traction motor/generator in at least one operating mode of said hybrid electric vehicle;

from time to time, dynamic braking said vehicle using said motor/generator, and returning to said batteries at least a portion of the electrical energy made available by said dynamic braking;

during those intervals in which said dynamic braking is not performed, charging said batteries from an auxiliary source of electrical power separate from said motor/generator, said charging being in an amount suitable for normal operation of said vehicle; and

during those intervals in which dynamic braking is being performed, charging said batteries from said auxiliary source of electrical power, at a rate reduced from said amount.

2. A method according to claim 1, wherein said step of charging said batteries from an auxiliary source of electrical power includes the step of charging said batteries from an electrical generator, separate from said motor/generator, driven by an internal combustion engine.

3. A method according to claim 2, wherein said step of charging said batteries from an electrical generator includes the step of charging said batteries from a generator driven by a diesel engine.

4. A method according to claim 1, wherein said step of charging said batteries from an electrical generator includes the step of charging said batteries from a fuel cell.

5. A hybrid electric vehicle, comprising:

at least one traction drive element contacting the support surface;

a traction electrical battery;

a traction motor/generator coupled to said traction element for transfer of mechanical energy therebetween;

an auxiliary electrical source separate from said traction motor/generator;

a controllable electrical interface electrically connected to said battery, said motor/generator, and said auxiliary electrical source; and

control means coupled to said controllable electrical interface, said battery, said motor/generator, and said auxiliary electrical source, for, (a) in a first mode of operation of said hybrid electrical vehicle, providing electrical energy to said motor/generator, for causing said motor/generator, operating in a motor mode of operation, to drive said traction drive element in order to propel said vehicle, (b) in a second mode of operation during which regenerative braking is not performed, providing electrical energy from said auxiliary source to said battery in an amount established by control laws depending, at least in part, upon the condition of said battery, and (c) in a third mode of operation, dynamically braking said vehicle by operating said motor/generator as a generator and returning to said battery at least a portion of the electrical energy resulting from said braking of said vehicle, and in said third mode of operation providing electrical energy from said auxiliary source to said battery in an amount less than that established by said control laws in the absence of said dynamic braking.