Battery charger

• US 6,275,010 B1
• Filed: 08/16/2000
• Issued: 08/14/2001
• Est. Priority Date: 08/25/1999
• Status: Expired due to Fees

• Current Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Original Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Inventors: Neuteboom, Harry
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): LUK, LAWRENCE W
• Application Number:
  US09/639,150
• Time in Patent Office: 363 Days
• Field of Search: 320/137, 320/140, 320/108, 320/127, 320/128, 320/162, 320/163, 320/164
• US Class Current: 320/137
• CPC Class Codes: H02J 2207/20 Charging or discharging characterised by the power electronics converter
• CPC Class Codes: H02J 7/02 for charging batteries from ac mains by converters
• 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 battery charger comprising a converter (CNV) for converting an input voltage (U_i) which is connected between an input terminal (1) and a reference terminal (GND) into a terminal voltage (V_k1) of a rechargeable battery (BT) which is connected between an output terminal (2) and the reference terminal (GND). The converter comprises a first and a second switch (SW₁, SW₂), a coil (L), a control circuit (CNTRL), a comparator (CMP), a frequency counter (CNT), and an indicator (IND). If the terminal voltage (V_k1) is lower than the reference voltage (V_RF), the start signal (ST) delivered by the comparator (CMP) will turn logic high. As a consequence the control circuit (CNTRL) will start an energy transfer cycle for transferring an amount of energy from the input terminal (1) to the rechargeable battery (BT). The frequency of the start signal (ST) decreases as the terminal voltage (V_k1) increases. By measuring the frequency of the start signal (ST) the indicator (IND) has the possibility of supplying a battery-high indication signal (BTHGH) when the rechargeable battery (BT) is almost full.

Claims

1. A battery charger comprising a converter (CNV) for converting an input voltage (U_i) between an input terminal (1) and a reference terminal (GND) into a terminal voltage (V_k1) of a battery (BT) between an output terminal (2) and the reference terminal (GND), comprising switching means (SM) for controlling the value of the terminal voltage (V_k1) to the value of a reference voltage (VRF), a control circuit (CNTRL) for controlling the switching means (SM), comparison means (CMP) for making a comparison of the terminal voltage (V_k1) with the reference voltage (VRF), and indication means (IND) for providing an indication signal (BTHGH) when the battery (BT) is substantially fully charged, characterized in that the converter (CNV) comprises a coil (L) with a first and a second terminal;

and in that the switching means (SM) comprise a first switch (SW₁) of which a control electrode is coupled to the control circuit (CNTRL) for receiving a first control signal (PHI₁) and a second switch (SW₂) of which a control electrode is coupled to the control circuit (CNTRL) for receiving a second control signal (PHI₂); and

in that the first terminal of the coil (L) is coupled to the input terminal (1); and

in that the first switch (SW₁) is connected between the second terminal of the coil (L) and the reference terminal (GND); and

in that the second switch (SW₂) is connected between the second terminal of the coil (L) and the output terminal (2); and

in that the comparison means (CMP) provide a start signal (ST) to the control circuit (CNTRL) in response to said comparison for initiating an energy transfer from the input terminal (1) to the battery (BT); and

in that the battery charger comprises frequency detection means (CNT) coupled for receiving the start signal (ST) and coupled to the indication means (IND) for providing the indication signal (BTHGH) when the frequency (f_ST) of the start signal (ST) has exceeded a certain limit.