High efficiency battery adapter

• US 4,747,034 A
• Filed: 03/05/1987
• Issued: 05/24/1988
• Est. Priority Date: 03/05/1987
• Status: Expired due to Fees

• Current Assignee: Dickey Carol S, Dickey David V
• Original Assignee: Carol S. Dickey, David V. Dickey
• Inventors: Dickey, David V.
• Primary Examiner(s): Skudy, R.
• Assistant Examiner(s): Hoff, Marc S.
• Application Number:
  US07/022,106
• Time in Patent Office: 446 Days
• Field of Search: 363/19, 363/22, 363/23, 340/636
• US Class Current: 363/23
• CPC Class Codes: H02J 7/0031 using battery or load disconnect circuits H02J9/002 takes precedence
• CPC Class Codes: H02M 3/3372 of the parallel type
• 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

Extremely high efficiency is achieved in a DC to DC converter by using a relaxation oscillator in which two transistors alternately conduct current to the primary winding of a step-up transformer. The transistors are interconnected by a resistor and capacitor in series so that when the converter is lightly loaded, the saturable reactor in the circuit will be self-resonant, so as to draw only minimal power from the battery source. The converter also includes a battery charge level monitor circuit that prevents the DC to DC converter from oscillating and thus providing power unless the battery is above a minimum charge level when its voltage is applied to the converter. In a preferred embodiment, the converter provides an output of up to 100 watts.

Claims

1. A DC to DC converter powered by a battery that has a positive terminal and a negative terminal and that provides current at an input voltage measured with respect to the negative terminal, said DC to DC converter comprising:

an operational amplifier coupled to the battery and responsive to the input voltage and so biased that when the input voltage is less than a certain voltage V₀, the output voltage of said operational amplifier is at the potential of the negative terminal of the battery, and when the input voltage increased above V₀, the output voltage of said operational amplifier increases in relation to the input voltage, until when the input voltage reaches a certain voltage V₁ indicating the battery is fully charged, the output voltage of said operational amplifier equals V₁ ;

an oscillator circuit that includes two transistors that alternately conduct current, each of said two transistors having a base, a collector, and an emitter, said oscillator circuit further comprising;

one saturable reactor having two primary windings and two feedback windings;

a resistor;

a capacitor; and

,

an output transformer having a center-tapped primary winding, the center tap connected to the positive terminal of the battery, and each end of the primary winding connected to the collector of one of said two transistors;

each emitter connected to the negative terminal of the battery through a primary winding of said saturable reactor;

each base connected to the output of said operational amplifier through a feedback winding of said saturable reactor so that the two transistors do not conduct and start oscillation unless the output voltage of said operational amplifier is greater than a certain voltage V₂ ;

the emitters connected by said resistor and said capacitor connected in series so that under lightly-loaded conditions when the current supplied by the transistors to the primary windings of said output transformer is minimal, said saturable reactor operates in a self-resonant mode to minimize power loss in said two transistors.