Computer power supply system

• US 5,541,490 A
• Filed: 05/18/1994
• Issued: 07/30/1996
• Est. Priority Date: 11/13/1992
• Status: Expired due to Term

• Current Assignee: NEC Corporation
• Original Assignee: Zenith Data Systems Corp. (Acer, Inc.)
• Inventors: Turnbull, Robert R., Shah, Rajesh A., Sengupta, Upal, Fritz, Brian C.
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): TSO, EDWARD H
• Application Number:
  US08/245,004
• Time in Patent Office: 804 Days
• Field of Search: 320/14, 320/2, 320/30, 320/48, 320/39, 320/22, 320/23, 320/24
• US Class Current: 320/160
• CPC Class Codes: G01R 31/3648 comprising digital calculation means, e.g. for performing an algorithm
• CPC Class Codes: G01R 31/374 with means for correcting the measurement for temperature or ageing
• CPC Class Codes: G01R 31/3842 combining voltage and current measurements
• CPC Class Codes: H01M 10/4257 Smart batteries, e.g. electronic circuits inside the housing of the cells or batteries
• CPC Class Codes: H01M 10/48 Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals, H01M50/569
• CPC Class Codes: H02J 7/00 Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
• CPC Class Codes: H02J 7/00036 Charger exchanging data with battery
• CPC Class Codes: H02J 7/00047 with provisions for charging different types of batteries
• CPC Class Codes: H02J 7/0068 Battery or charger load switching, e.g. concurrent charging and load supply H02J7/0013 takes precedence
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y10S 320/10 Nonbattery load controls charging

Abstract

A power supply system, for example, for use with a portable personal computer, includes a smart battery pack and a charging system. The smart battery pack is provided with a dedicated microcontroller for controlling the charging level of the battery charger system. In particular, the status of the battery including the voltage and temperature of the battery is applied to the microcontroller along with a signal representative of the current load demand of the computer system. The microcontroller, in turn, provides a control signal in the form of fixed frequency, variable duty cycle pulse width modulated (PWM) signal for controlling the charging level of the battery charger system. The duty cycle of the PWM signal is used to regulate the charging current supplied by the battery charger. In particular, the DC value of the PWM signal is used as a reference to control the charging current of the regulator to provide a variable output charging current with a relatively wide current range. As such, the battery charger is adapted to efficiently utilize the residual capacity of the battery charger system for optimizing charging of the battery packs during all operating conditions of the computer system. Moreover, the use of a PWM signal from the battery pack to control the battery charger enables a single type of battery charger to be utilized for various battery technologies.

Claims

1. A battery charger having a predetermined capacity for charging one or more battery cells comprising:

means for providing variable charging current to said one or more battery cells, wherein said variable charging current is continuously and automatically variable from a predetermined minimum to a predetermined maximum level during all operating conditions of said battery charger; and

means for providing a regulated source of DC voltage adapted to be connected to a load having a predetermined power requirement.

2. A battery charger as recited in claim 1, wherein said battery charger includes means for measuring a load current;

and

means for limiting the charging current applied to said one or more battery cells as a function of the power requirements of the load connected to said providing means.

3. A battery charger as recited in claim 2, wherein said limiting means includes means for controlling the providing means as a function of the predetermined capacity of said battery charger and the power requirements of said load connected to said providing means.