Battery charger device

• US 5,420,494 A
• Filed: 01/31/1994
• Issued: 05/30/1995
• Est. Priority Date: 01/31/1994
• Status: Expired due to Fees

• Current Assignee: Chao-Cheng Lu
• Original Assignee: Chao-Cheng Lu
• Inventors: Lu, Chao-Cheng
• Primary Examiner(s): KINCAID, KRISTINE LYNN
• Application Number:
  US08/188,820
• Time in Patent Office: 484 Days
• Field of Search: 320/21, 320/31, 320/32, 320/33, 320/39, 320/40, 320/57, 320/59
• US Class Current: 320/138
• 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

Abstract

A battery charging device capable of charging any variety of rechargeable batteries and capable of being powered by either a 110 volt or a 220 volt A.C. power source. The battery charging device comprises an integrator circuit having a D.C. power source; a voltage comparator; a solid state relay; a D.C. output circuit; a positive voltage feedback circuit; and a negative voltage feedback circuit. The integrator circuit receives A.C. power from an A.C. power source and provides an output to the voltage comparator. The voltage comparator, in turn, is connected so as to provide an output to the solid state relay. The solid state relay preferably includes a zero voltage closing circuit and provides an output to the D.C. output circuit. The D.C. output circuit is connected to a battery-to-be-charged and provides an output D.C. voltage thereto. The D.C. output circuit is also connected to and provides outputs to the negative and positive feedback circuits which, in turn, provide feedback to the voltage comparator. Preferably, optical coupling devices connect the output from the voltage comparator to the solid state relay, as well as the positive and negative feedback circuits to the voltage comparator.

Claims

1. A battery charger device for connection to an A.C. power source comprising, an integrator circuit having a D.C. power source, a voltage comparator having at least a first and a second input terminal and an output terminal, a solid state relay circuit, a D.C. output circuit, a positive voltage feedback circuit, and a negative voltage feedback circuit;

said integrator circuit having a full wave rectifier for rectifying A.C. power from said A.C. power source, said integrator circuit processing said A.C. power to form an impulse wave from said A.C. power which is further processed by said integrator circuit to form a synchronous triangular wave which is directly transmitted to said first input terminal of the voltage comparator;

said voltage comparator being responsive to said triangular wave transmitted by said integrator circuit and being further responsive to a D.C. voltage output from said negative voltage feedback circuit and transmitted to said second input terminal so as to provide a synchronous square wave output at said output terminal, said square wave having a temporal width which is changed subject to the magnitude of said D.C. voltage on said second input terminal, and said D.C. voltage magnitude being subject to change in the same manner as determined by said positive voltage feedback circuit, said square wave output from said voltage comparator being directly coupled with a photo coupler of said solid state relay circuit;

said solid state relay circuit comprising, a second full wave rectifier for rectifying said A.C. power for the performance of synchronous conduction with said synchronous square wave to thereby provide a synchronous conduction voltage which is then transmitted to said D.C. output circuit by means of direct coupling;

said D.C. output circuit filtering said synchronous conduction voltage from said solid state relay circuit so as to provide a second D.C. voltage, and a voltage containing a certain angle of sine wave function hence formed on an output terminal of said D.C. output circuit by using a voltage regulation method, said output terminal of said D.C. output circuit defining a sampling voltage point which is connected to an input terminal of said positive voltage feedback circuit and negative voltage feedback circuit said D.C. output circuit being coupled to said positive voltage feedback circuit and negative voltage feedback circuit;

said positive voltage feedback circuit, sampling said voltage at the sampling voltage point of the D.C. output circuit formed as a basis for advancing said D.C. voltage output to the second input terminal of the voltage comparator, said positive voltage feedback circuit having a photo coupling means between an output terminal of said positive voltage feedback circuit and said voltage comparator;

said negative voltage feedback circuit, sampling said voltage at the sampling voltage point of the D.C. output circuit formed as a basis for reducing said D.C. voltage output to the second input terminal of the voltage comparator, said negative voltage feedback circuit having a photo coupling means between an output terminal of said negative voltage feedback circuit and said voltage comparator.

2. The battery charger device of claim 1 wherein said negative voltage feedback circuit comprises a light emitting diode, which is in one of the following states:

off when a battery being charged is below a preset voltage, flashes when the voltage of said battery being charged is close to a saturation voltage level and remains on constantly when the battery being charged is fully charged; and

wherein said positive voltage feedback circuit comprises a light emitting diode, which is operated reversely with respect to the light emitting diode of said negative voltage feedback circuit.

3. The battery charger device of claim 1 further comprising a sampling voltage output terminal coupled to said positive voltage feedback circuit and negative voltage feedback circuit to detect a charging voltage from said D.C. output circuit.

4. The battery charger device of claim 1, wherein said positive voltage feedback circuit operates such that, when the voltage at the sampling voltage point is less than a preset value for said positive voltage feedback circuit, the positive voltage feedback circuit causes an increase in the temporal width of the synchronous square wave from said voltage comparator so as to advance said second D.C. voltage, and wherein said positive voltage feedback circuit comprises a voltage comparator circuit, a time delay circuit and a photo coupler circuit directly coupled to one another;

said voltage comparator circuit comprising a common voltage comparator IC;

said time delay circuit comprising a current limiting resistor, a transistor, a collector resistor, an emitter capacitor and an emitter follower, a delay time of said time delay circuit being determined subject to the resistance of the collector resistor and the capacitance of the emitter capacitor;

said photo coupler circuit comprising a photo coupler IC having an input terminal connected to an emitter resistor of the emitter follower of the time delay circuit, and an output terminal having a resistor connected in parallel therewith, one end of the parallel-connected resistor being connected to an input power terminal of said voltage comparator and another end of said parallel-connected resistor being a common grounding end.

5. The battery charger device of claim 1, wherein said negative voltage feedback circuit operates such that, when the voltage at the sampling voltage point is more than a preset value for said negative voltage feedback circuit, the negative voltage feedback circuit causes a reduction in the temporal width of the synchronous square wave from said voltage comparator so as to lower said second D.C. voltage, and wherein said negative voltage feedback circuit comprises a voltage comparator circuit and a photo coupler circuit connected directly thereto;

said voltage comparator circuit comprising a common voltage comparator IC;

said photo coupler comprising a photo coupler IC having an input terminal connected to an output terminal of said voltage comparator IC by means of direct coupling, and an output terminal having a parallel connected resistor, one end of said parallel connected resistor being connected to said D.C. power source and another end of said parallel connected resistor being connected to the second input terminal of said voltage comparator.

6. The battery charger device of claim 1 wherein the battery to be charged can be one of a hydro-nickel battery, nickel-chrome battery, lead storage battery.

7. The battery charger device of claim 1, wherein said solid state relay circuit comprises a zero voltage closing circuit having a plurality of resistors and transistors, one of said resistors being connected in parallel to the output terminal of a photo coupler device, the impedance of said output terminal of the photo coupler device being changed by switching an output terminal of the photo coupler device between ON and OFF so as to control an A.C. thyristor in turning on an A.C. power source voltage as the transistors are off;

the resistors of said zero voltage closing circuit being connected in series, the photo coupler device being replaceable by one of a relay and a photo thyristor.

8. The battery charger device of claim 1 wherein said battery charger device operates in a charging status when the sine wave function voltage of the A.C. power is higher than the voltage of a battery being charged;

and operates in a non-charging status when the sine wave function voltage of the A.C. power is lower than the voltage of the battery being charged.

9. The battery charger device of claim 1, wherein said battery charger device operates such that when a battery is initially charged, the battery charger device provides a charging current having a maximum magnitude, the charging current being gradually reduced after charging commences, and wherein the D.C. output circuit charges the battery intermittently when the voltage of the battery is close to a saturation state, said charging current becoming zero when charging is finished, and wherein the D.C. output circuit automatically charges the battery when the voltage of the battery drops to a predetermined level so that the battery is constantly maintained at the saturation voltage.