Battery charging circuit

• US 8,415,929 B2
• Filed: 02/05/2009
• Issued: 04/09/2013
• Est. Priority Date: 02/06/2008
• Status: Active Grant

• Current Assignee: Shindengen Electric Manufacturing Company Limited
• Original Assignee: Shindengen Electric Manufacturing Company Limited
• Inventors: Tabuta, Makoto
• Primary Examiner(s): Fantu, Yalkew
• Application Number:
  US12/865,941
• Publication Number:
  US 20100327817A1
• Time in Patent Office: 1,524 Days
• Field of Search: 320/148
• US Class Current: 320/148
• CPC Class Codes: H01M 10/44 Methods for charging or discharging circuits for charging H02J7/00
• CPC Class Codes: H02J 7/1484 by commutation of the output windings of the generator
• CPC Class Codes: H02J 7/1492 by means of controlling devices between the generator output and the battery
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• 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

An example battery charging circuit includes a rectifier circuit for rectifying a three-phase AC voltage outputted from an electric power generator and generating a charge voltage for charging a battery. A voltage detection circuit detects that the voltage of the battery exceeds a predetermined voltage. A switching circuit, in an off-state, charges the battery through the rectifying circuit and, in an on-state, short-circuits the electric power generator through the rectifier circuit. A switch control circuit brings the switching circuit into the on-state, when it is detected by the voltage detection circuit that the voltage of the battery exceeds the predetermined voltage. A control circuit allows the switch control circuit to subsequently perform a control for bringing the switching circuit into the off-state.

Claims

1. A battery charging circuit comprising:

a rectifier circuit for rectifying a three-phase alternate-current voltage outputted from an electric power generator and generating a charge voltage for charging a battery;

a voltage detection circuit for detecting that a voltage of the battery becomes equal to or higher than a predetermined voltage;

a switching circuit for charging, in an off-state, the battery through the rectifier circuit and for short-circuiting, in an on-state, the electric power generator through the rectifier circuit;

a switch control circuit for switching the switching circuit to the on-state when the voltage detection circuit detects that the voltage of the battery becomes equal to or higher than the predetermined voltage; and

a control circuit for controlling the switching circuit to switch from the on-state to the off-state and to maintain the off-state, and controlling the switching circuit to switch from the off-state to the on-state and to maintain the on-state,

wherein the control circuit comprises a capacitor that is charged when the switch control circuit controls the switching circuit to switch to the on-state, the capacitor discharging when the switch control circuit controls the switching circuit to switch to the off-state,

the voltage detection circuit comprises a first transistor, a base of the first transistor being reverse-biased by the capacitor discharging,

the switch control circuit comprises a second transistor, a base of the second transistor being connected to a collector of the first transistor, the switch control circuit controlling the on-state and the off-state of the switching circuit based on a collector current flowing to the collector of the first transistor, and

the capacitor in the control circuit is connected between the base of the first transistor and a collector of the second transistor.