BATTERY CHARGING AND DISCHARGING APPARATUS

• US 3,708,738 A
• Filed: 12/22/1970
• Issued: 01/02/1973
• Est. Priority Date: 12/22/1970
• Status: Expired due to Term

• Current Assignee: James Frezzolini, James J. Crawford
• Original Assignee: James Frezzolini, James J. Crawford
• Inventors: Crawford, James J., Frezzolini, James
• Primary Examiner(s): Miller, J. D.
• Assistant Examiner(s): Hickey, Robert J.
• Application Number:
  US05/100,593
• Time in Patent Office: 742 Days
• Field of Search: 320/2,5,6,7,8,9,39,40,16,27,28 317/13,33,16 323/225CR,22SC
• US Class Current: 320/134
• CPC Class Codes: H02J 2207/20 Charging or discharging characterised by the power electronics converter
• CPC Class Codes: H02J 7/0031 using battery or load disconnect circuits H02J9/002 takes precedence
• CPC Class Codes: H02J 7/02 for charging batteries from ac mains by converters
• CPC Class Codes: Y10S 320/13 Fault detection
• CPC Class Codes: Y10S 320/19 Charger status, e.g. voltmeter
• CPC Class Codes: Y10S 320/22 Line impedance, e.g. resistor
• CPC Class Codes: Y10S 320/27 Transformerless

Abstract

The apparatus includes a battery charger having a pair of input terminals adapted to be connected to an AC source of potential and a pair of output terminals adapted to be connected to the respective terminals of a battery. A rectifier converts the AC energy to DC. A series connected SCR is operable to connect the source with the battery when the battery potential is below a predetermined value. A reactance is provided to lower the source potential and to obtain substantially constant current for charging purposes. A shunt connected SCR is provided to limit the potential applied to the series SCR when the battery is charged to protect the battery and the series connected SCR. The apparatus further includes a discharger which is operable to disconnect a load from the battery when the battery potential drops to a preselected value, thereby to protect the battery from completely discharging.

Claims

1. Battery apparatus including a battery charger having a pair of input terminals adapted to be connected to a source of energy, a pair of output terminals adapted to be connected to the respective terminals of a battery, circuit means for connecting said pair of input terminals with said pair of output terminals, said circuit means comprising first switch means connected between at least one of said pair of input and output terminals and operable from a first state to a second state in response to the potential of said battery for connecting said source of energy with said battery when said battery potential is below a preselected value, and second switch means connected between said pair of input terminals and responsive to said first switch means for shunting said source of energy away from said first switch means when said first switch means is in said first state, and a discharger connected between said pair of output terminals, said discharger comprising a pair of load terminals adapted to be connected across a load, and third switch means operable to connect said output terminals with said load terminals whereby the battery supplies energy to the load and being responsive to the potential of said battery to disconnect at least one of said pair of load terminals from said one output terminal when the battery potential reaches a predetermined value, said third switch means comprising a relay winding having a first and a second pair of contacts and operable to connect together each contact of said pair of contacts when energized, sensing means connected in series with said relay winding for de-energizing said relay winding when said battery potential reaches said predetermined value, lead means for connecting said first pair of contacts between said one output and load terminals and said second pair of contacts between said one output terminal and said series circuit of said relay winding and said sensing means for establishing a holding circuit there between, and selectively operable energizing means for connecting said one output terminal with said series circuit of said relay winding and sensing means to initially energize said relay winding.

2. Battery protection apparatus including a battery charger for charging a battery, said battery charger comprising a pair of input terminals adapted to be connected across a source of potential, a pair of output terminals adapted to be connected to respective terminals of the battery, a first semiconductor switch means having an input electrode connected to said one input terminal, an output electrode connected to one of said output terminals and a control electrode and being operable to switch from a non-conducting to a conducting state in response to a control signal applied to said control electrode to connect together said one input and output terminalS, a lead connecting the other of said pair of input terminals with the other of said pair of output terminals, a capacitive reactance connected in series with said first semiconductor switch means, first control signal generating means connected to said one output for applying the control signal to said control electrode of said first semiconductor switch means when the battery potential is below a preselected level, shunt means connected between said input electrode of said first semiconductor switch means and said lead and movable from a non-conducting to a conducting state in response to a second control signal for clamping the potential at said first semiconductor switch means input electrode to a predetermined value, and second control signal generating means connected between said pair of input terminals for applying said second control signal to said shunt means when the potential there across is equal to said predetermined level wherein the minimum value of said predetermined value is equal to said preselected level.

3. Battery protection apparatus as in claim 2, wherein said first semiconductor switch means comprising an SCR having a anode electrode corresponding to said input electrode and connected to said one input terminal, a cathode electrode corresponding to said output electrode and connected to said one output terminal, and a gate electrode corresponding to said control electrode and connected to said first signal generating means.

4. Battery apparatus as in claim 3 in which said capacitive reactance comprises at least a first capacitor, a second capacitor, and means for selectively connecting said first and second capacitors together to provide a selectively variable capacitive reactance.

5. Battery protection apparatus as in claim 3, and a radio frequency filter connected in series with said first SCR.

6. Battery protection apparatus as in claim 3, in which said source of potential is an AC source of potential, and a rectifier connected between said input terminals and having a pair of output terminals, said first semiconductor switch means being connected to said one input terminal through one of said rectifier output terminals and said lead being connected to said other input terminal to said other rectifier output terminal, whereby a DC potential is applied to said first SCR and said shunt means.

7. Battery protection apparatus as in claim 3, in which said shunt means comprises an SCR having an anode electrode connected to said anode electrode of said first SCR, a cathode electrode connected to said lead, and a gate electrode connected to said second control signal generating means.

8. Battery protection apparatus as in claim 3, further including a discharger, said discharger comprising a pair of load terminals adapted to be connected across a load, disconnect means for connecting said one output terminal with one of said pair of load terminals and for disconnecting said one output terminal therefrom in response to the battery terminal potential falling below a preselected level, sensing means for sensing the battery terminal potential, isolation means for isolating said sensing means from transient signals, and a lead connecting said other output terminal with the other of said pair of load terminals.

9. Battery protection apparatus as in claim 8, and means for selectively energizing said battery charger when in a first stage, and for energizing said battery discharger and deenergizing said battery charger when in a second state.

10. Battery apparatus as in claim 8, in which said battery comprises a plurality of cells, said discharger further comprising selectively operable connecting means movable for connecting said plurality of cells in series when in a first state and for connecting said cells in parallel when in a second state, unidirectional current conducting means connected with said connecting means and adapted to be connected in series with at lease one cell when said connecting means is in said second state to pRevent reverse current flow through said one cell during discharge.

11. Battery apparatus as in claim 10, in which said unidirectional current conducting means comprises a respective diode for each one of said plurality of cells adapted to be connected in series with the associated cell by said connecting means when said connect means is in said second state and to be disconnected therefrom when said connecting means is in said first state.