Traction motor current control battery monitoring system

• US 5,107,191 A
• Filed: 09/30/1983
• Issued: 04/21/1992
• Est. Priority Date: 06/28/1980
• Status: Expired due to Fees

• Current Assignee: Lucas Industries Limited (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Original Assignee: Lucas Industries Limited (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Inventors: Arlidge, Neville J., Lowndes, Michael W., Adams, Derek S.
• Primary Examiner(s): Ro, Bentsu
• Application Number:
  US07/537,970
• Time in Patent Office: 3,126 Days
• Field of Search: 318/139, 318/434, 320/2, 320/15, 320/17, 320/32, 320/43, 320/48, 324/427, 324/429, 324/430, 324/433, 324/434
• US Class Current: 318/139
• CPC Class Codes: B60L 15/2045 for optimising the use of energy
• CPC Class Codes: B60L 58/15 Preventing overcharging
• CPC Class Codes: B60L 58/18 of two or more battery modules
• CPC Class Codes: G01R 31/006 on road vehicles, e.g. automobiles or trucks testing of ignition installations peculiar to internal combustion engines F02P17/00
• CPC Class Codes: G01R 31/3648 comprising digital calculation means, e.g. for performing an algorithm
• CPC Class Codes: G01R 31/3835 involving only voltage measurements
• CPC Class Codes: G01R 31/396 Acquisition or processing of data for testing or for monitoring individual cells or groups of cells within a battery
• CPC Class Codes: H02J 7/00714 in response to battery charging or discharging current
• 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
• CPC Class Codes: Y10S 320/18 Indicator or display
• CPC Class Codes: Y10S 320/21 State of charge of battery
• CPC Class Codes: Y10S 320/34 Robot, hybrid, recreational or emergency vehicle

Abstract

A microprocessor based electric vehicle traction battery monitoring system evaluates the state of charge, interfaces with a traction motor control system, and controls recharging. The state of charge is evaluated during the first part of discharge by integrating the current after compensating it for rate of discharge and during the last part of discharge by dividing the battery into sub-packs and evaluating the state of charge from the lowest sub-pack voltage compensated for polarization voltage. The charge storage capacity is also calculated from the lowest sub-pack voltage. The maximum traction motor current is progressively limited during the last part of discharge. During charging, the charge withdrawn is replaced while progressively reducing the charging current and the battery is then charged at a constant current until the rate of rise of the lowest sub-pack voltage falls below a fixed level.

Claims

1. A combined motor control and battery monitoring system for an electric vehicle having a main electric traction motor, said system comprising:

a traction battery pack having a plurality of cells connected in series for providing power to the traction motor, said battery pack being divided into a plurality of sub-packs each of which includes one or more cells;

means for controlling the current supplied to the traction motor;

means for determining when a voltage of the sub-packs having the lowest voltage falls below a critical value;

means interconnected with the controlling means and the determining means for restricting the current supply to the traction motor when the lowest sub-pack voltage falls below said critical value; and

wherein the determining means is responsive to the battery current, the determining means calculates polarization voltage as a function of battery current and time, and the determining means compensates the individual sub-pack voltages for the polarization voltage.