Battery charger and charge control circuit

• US 6,297,617 B1
• Filed: 09/05/2000
• Issued: 10/02/2001
• Est. Priority Date: 09/07/1999
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Toyoda Jidoshokki Seisakusho
• Original Assignee: Kabushiki Kaisha Toyoda Jidoshokki Seisakusho
• Inventors: Aoyama, Takashi
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): LUK, LAWRENCE W
• Application Number:
  US09/654,490
• Time in Patent Office: 392 Days
• Field of Search: 320/128, 320/127, 320/156, 320/157, 320/161, 320/152
• US Class Current: 320/128
• CPC Class Codes: H02J 2207/20 Charging or discharging characterised by the power electronics converter
• CPC Class Codes: H02J 7/007182 in response to battery voltage
• CPC Class Codes: H02J 7/02 for charging batteries from ac mains by converters
• CPC Class Codes: H02J 7/04 Regulation of charging current or voltage
• CPC Class Codes: H02M 1/0009 Devices or circuits for detecting current in a converter
• CPC Class Codes: H02M 1/0025 Arrangements for modifying reference values, feedback values or error values in the control loop of a converter
• CPC Class Codes: H02M 3/1588 comprising at least one synchronous rectifier element H02M3/1582, H02M3/1584 take precedence
• CPC Class Codes: Y02B 40/00 Technologies aiming at improving the efficiency of home appliances, e.g. induction cooking or efficient technologies for refrigerators, freezers or dish washers
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

A switch is controlled by a charging control unit. An inductor is provided between the switch and a secondary battery. An offset generation unit generates voltage V2 by adding an offset voltage V_os to voltage V1, where the voltage V1 corresponds to an inductor current. A current detection unit detects the inductor current based on the voltage V2. A voltage detection unit detects output voltage V_out. A charging control unit controls the switch based on the inductor current detected by the current detection unit and the output voltage V_out detected by the voltage detection unit.

Claims

1. A charging control circuit for controlling an operation of a battery charger including a switch to which DC voltage is applied and an inductor connected to the switch, comprising:

offset means for adding an offset to a signal corresponding to an inductor current;

conversion means for generating a current corresponding to the signal to which the offset is added;

correction means for eliminating an effect due to the offset from the current generated by said conversion means; and

control means for controlling the switch based on the current corrected by said correction means.

2. The charging control circuit according to claim 1, wherein

the offset is a value which prevents a polarity of voltage inputted to said conversion means from changing, regardless of a direction of inductor current.

3. The charging control circuit according to claim 1, wherein

said correction means generates a correction current corresponding to the offset and eliminates the correction current from the current generated by said conversion means.

4. A charging control circuit for controlling an operation of a battery charger including a switch to which DC voltage is applied and an inductor connected to the switch, comprising:

an offset circuit adding an offset to a signal corresponding to an inductor current;

a conversion circuit generating a current corresponding to the signal to which the offset is added;

a correction circuit eliminating an effect due to the offset from the current generated by said conversion circuit; and

a controller controlling the switch based on the current corrected by said correction circuit.

5. A charging control circuit for controlling an operation of a battery charger including a switch to which DC voltage is applied and an inductor connected to the switch, comprising:

a resistor which is connected to the inductor in series;

an amplifier which comprises a first input terminal and a second input terminal, the first input terminal being connected to one end of said resistor and the second input terminal being connected to the other end of said resistor;

an offset circuit applying an offset voltage to the first input terminal of said amplifier;

a feedback circuit generating a feedback signal based on an output of said amplifier in such a way that a potential of the first input terminal of said amplifier and a potential of the second input terminal of said amplifier become the same, and supplying the feedback signal to the second input terminal of said amplifier; and

a controller controlling the switch based on the output of said feedback circuit.

6. The charging control circuit according to claim 5, wherein

said controller controls the switch after eliminating an effect due to the offset from the output of said feedback circuit.

7. A battery charger including a switch to which DC voltage is applied and an inductor connected to the switch, comprising:

offset means for adding an offset to a signal corresponding to an inductor current;

conversion means for generating a current corresponding to the signal to which the offset is added;

correction means for eliminating an effect due to the offset from the current generated by said conversion means; and

control means for controlling the switch based on the current corrected by said correction means.

8. A charging control method for controlling an operation of a battery charger including a switch to which DC voltage is applied and an inductor connected to the switch, comprising:

adding an offset to a signal corresponding to an inductor current;

generating a current corresponding to the signal to which the offset is added;

eliminating the effect due to the offset from the generated current; and

controlling the switch based on the current from which the effect due to the offset has been eliminated.