Charging circuit and charger using the same

• US 7,605,563 B2
• Filed: 06/10/2004
• Issued: 10/20/2009
• Est. Priority Date: 06/17/2003
• Status: Expired due to Fees

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Mori, Hiroyuki, Kanno, Masayoshi, Yamada, Shinichiro, Noguchi, Tsutomu
• Primary Examiner(s): Ullah; Akm E
• Assistant Examiner(s): BOATENG, ALEXIS ASIEDUA
• Application Number:
  US10/865,612
• Publication Number:
  US 20040263125A1
• Time in Patent Office: 1,958 Days
• Field of Search: 320/114, 320/123, 320/125, 320/138, 320/140
• US Class Current: 320/123
• CPC Class Codes: H02J 7/1492 by means of controlling devices between the generator output and the battery
• CPC Class Codes: H02P 9/48 Arrangements for obtaining a constant output value at varying speed of the generator, e.g. on vehicle H02P9/04 - H02P9/46 take precedence
• CPC Class Codes: Y02T 10/92 Energy efficient charging or discharging systems for batteries, ultracapacitors, supercapacitors or double-layer capacitors specially adapted for vehicles

Abstract

A charging circuit includes a generator, a step-down circuit for reducing an output voltage of the generator to a predetermined voltage, a current controller for controlling a charging current that is supplied from the step-down circuit to a secondary battery, based on an amount of power generated by the generator, a mode selector for selecting charging modes, and a monitor for monitoring an amount of stored electricity. The step-down circuit receives an output of the generator, in charging, at a high voltage and a small current and is used to charge the battery at a low voltage and a large current.

Claims

1. A charging circuit for charging a battery, comprising:

a generator operable to generate an output voltage;

a step-down circuit operable to reduce the output voltage of said generator to a predetermined lower voltage;

a current controller operable to control a charging current based on an amount of power generated by said generator, said charging current intended for supply from said step-down circuit to said battery, said current controller having a current-controlling element and a current-limiting resistor, in which said current-controlling element is a number of transistors; and

a mode selector for selecting a charging mode from among a plurality of modes for charging said battery, said mode selector having a resistor and a switch coupled to the number of transistors of said current-controlling element so as to control a flow of base current therethrough, wherein said plurality of modes includes a current-preferred mode for maximizing the charging current supplied to said battery and an efficiency-preferred mode for maximizing utilization of the power taken out of said generator,

wherein a total sum of a resistance component of said battery and a resistance of the current-limiting resistor is set to be not less than a negative resistance component of said current-controlling element.

2. The charging circuit according to claim 1, wherein a coil of said generator has a delta connection.

3. The charging circuit according to claim 1, wherein said step-down circuit is a step-down type DC-DC converter for regulating a voltage generated by said generator to a constant voltage.

4. The charging circuit according to claim 1, further comprising a monitor circuit for monitoring an amount of electricity stored in said battery, said monitor circuit having a detector for detecting the amount of stored electricity by multiplying the charging current and a charging time.

5. The charging circuit according to claim 4, wherein said monitor circuit monitors the charging current based on one of an input voltage applied to said step-down circuit and an average value of pulses of a switching element driver.

6. A charger for charging a battery, said charger comprising:

a generator operable to generate an output voltage;

a step-down circuit operable to reduce the output voltage of said generator to a predetermined lower voltage;

a current controller operable to control a charging current based on an amount of power generated by said generator, said charging current intended for supply from said step-down circuit to said battery, said current controller having a current-controlling element and a current-limiting resistor, in which said current-controlling element is a number of transistors; and

a mode selector for selecting a charging mode from among a plurality of modes for charging said battery, said mode selector having a resistor and a switch coupled to the number of transistors of said current-controlling element so as to control a flow of base current therethrough, wherein said plurality of modes includes a current-preferred mode for maximizing the charging current supplied to said battery and an efficiency-preferred mode for maximizing utilization of the power taken out of said generator,

wherein a total sum of a resistance component of said battery and a resistance of said current-limiting resistor is set to be not less than a negative resistance component of said current-controlling element.

7. The charger according to claim 6, wherein a coil of said generator has a delta connection.

8. The charger according to claim 6, wherein said step-down circuit is a step-down type DC-DC converter for regulating a voltage generated by said generator to a constant voltage.

9. The charger according to claim 6, further comprising a monitor circuit for monitoring an amount of electricity stored in said battery, said monitor circuit having a detector for detecting the amount of stored electricity by multiplying the charging current and a charging time.

10. The charger according to claim 9, wherein said monitor circuit monitors the charging current based on one of an input voltage applied to said step-down circuit and an average value of pulses of a switching element driver.