Voltage boost circuit for DC power supply

• US 4,054,827 A
• Filed: 04/12/1976
• Issued: 10/18/1977
• Est. Priority Date: 04/12/1976
• Status: Expired due to Term

• Current Assignee: United States Of America As Represented By The Secretary Of The Army (Government of the United States of America)
• Original Assignee: The United States Of America As Represented By The Secretary Of The Army
• Inventors: Reimers, Eberhart
• Primary Examiner(s): Shoop, William M.
• Application Number:
  US05/676,271
• Time in Patent Office: 554 Days
• Field of Search: 321/20, 321/2
• US Class Current: 363/28
• CPC Class Codes: H02M 3/3155 with automatic control of the output voltage or current

Abstract

A typical "stand alone" precision power DC to AC solid state converter reres a higher DC supply voltage than is usually available from its utility power sources. The disclosed invention is a voltage boost circuit that provides the DC-bus voltage amplitude for precision power DC to AC solid state converters by transforming only the difference between the available raw power DC voltage bus and the required precision DC voltage amplitude. This DC voltage difference obtained by the circuitry of this invention is boot-strapped to the available DC bus to obtain the required precision DC voltage.

Claims

1. A voltage boost circuit requiring minimum energy transfer to sustain rated power profile comprising:

a. means for obtaining a first direct current voltage;

b. a first conductive lead and a second conductive lead coupled to the output of said means for obtaining said first direct current voltage;

c. means connected between said first and second conductive leads for generating an alternating current voltage which comprises

a first thyristor and second thyristor connected in series between said first and second conductive leads, said first and second thyristors each having a gate electrode;

a transformer having a primary winding, a first secondary winding and a second secondary winding;

means to couple said primary winding to the common point of said first and second thyristors; and

means coupled to said gate electrode of said first thyristor and the said gate electrode of said second thyristor for alternately gating on said first and second thyristors;

d. means for deriving a second direct current voltage from said generated alternating current voltage, said means for deriving said second direct current voltage being coupled directly to the first and second secondary windings of said means for generating said alternating current voltage;

e. a first output lead and a second output lead; and

f. means to apply said first direct current voltage and said second direct current voltage on said first and second output leads in such a manner that said first and said second direct current voltages are added to form a third direct current voltage.

2. A voltage boost circuit as defined in claim 1 wherein said means for deriving said second direct current voltage from said generated alternating current voltage comprises:

a first rectifier diode connected to one end of said first secondary winding, a second rectifier diode connected between the other end of said first secondary winding and said first rectifier diode, a third rectifier diode connected to one end of said second secondary winding and a fourth rectifier diode connected between the other end of said second secondary winding and said third rectifier diode.

3. A voltage boost circuit as defined in claim 2 wherein said means to apply said first and said second direct current voltages on said first and second output leads comprises means to connect the common point of said first and second rectifier diodes to said first output lead, a first coupling capacitor connected between said first conductive lead and said first output lead, means to connect the common point of said third and fourth rectifier diodes to said second output lead and a second coupling capacitor connected between said second conductive lead and said second output lead.

4. A voltage boost circuit as defined in claim 3 wherein a first capacitor is connected in parallel with said primary winding and wherein said means to couple the common point of said first and second thyristors to said primary winding comprises an inductor and a second capacitor connected in series between said common point of said first and second thyristors and one end of said primary winding and one end of said first capacitor, the other end of said primary winding and the other end of said first capacitor both being connected to ground.

5. A voltage boost circuit as defined in claim 4 wherein said means for obtaining said first direct current voltage comprises an alternating current source and a full wave rectifier coupled between said alternating current source and said first and second conductive leads.

6. A voltage boost circuit as defined in claim 1 wherein said means for alternately gating on said first and second thyristors comprises:

a voltage controlled oscillator having an input and a first output and a second output;

a first trigger circuit coupled between said gate electrode of said first thyristor and said first output of said voltage controlled oscillator;

a second trigger circuit coupled between said gate electrode of said second thyristor and said second output of said voltage controlled oscillator;

a summing amplifier having an output coupled to said input of said voltage controlled oscillator and having an inverting input and a non-inverting input;

a first resistor coupled between said first output lead and said inverting input of said summing amplifier;

a voltage follower amplifier having an output coupled to said inverting input of said summing amplifier and having a second output lead connected to its inverting input;

a second resistor coupled between said inverting input of said summing amplifier and a voltage follower;

a feedback network coupled between said inverting input of said summing amplifier and said output of said summing amplifier;

a third and fourth resistor connected between said first output lead and said inverting input of said summing amplifier;

a fifth and sixth resistor connected between said non-inverting input of said summing amplifier and said first output lead; and

a Zener diode connected between the common point of said fifth and sixth resistors and ground.

7. A voltage boost circuit as defined in claim 6 wherein said means for obtaining said first direct current voltage comprises:

an alternating current source and a full wave rectifier connected between said alternating current source and said first and second conductive leads.

8. A voltage boost circuit as defined in claim 7 wherein said alternating current source is a single phase source.

9. A voltage boost circuit as defined in claim 7 wherein said alternating current source is a three phase source.

10. A voltage boost circuit as defined in claim 8 wherein said alternating current source has a neutral conductor and wherein first and second diodes are coupled in series between said first and second conductive leads and the common point of said first and second diodes is connected to ground and to said neutral conductor.

11. A voltage boost circuit as defined in claim 9 wherein said alternating current source has a neutral conductor and wherein first and second diodes are coupled in series between said first and second conductive leads and the common point of said first and second diodes is connected to ground and to said neutral conductor in combination with a split phase capacitor filter bank.