DC-DC converter

• US 3,909,696 A
• Filed: 12/26/1973
• Issued: 09/30/1975
• Est. Priority Date: 12/27/1972
• Status: Expired due to Term

• Current Assignee: Kazuo Katou, Yasuji Kamata
• Original Assignee: Kazuo Katou, Yasuji Kamata
• Inventors: Kamata, Yasuji, Katou, Kazuo
• Primary Examiner(s): Pellinen, A. D.
• Application Number:
  US05/428,020
• Time in Patent Office: 643 Days
• Field of Search: 321/2,18,45R 323/17,22T,DIG.1
• US Class Current: 363/21.16
• CPC Class Codes: H02M 3/3376 with automatic control of output voltage or current
• CPC Class Codes: H02M 3/3385 with automatic control of output voltage or current H02M3/33561 takes precedence

Abstract

A DC-DC converter in which a series circuit of a switching element and an input winding of a transformer is connected to a DC power supply so that a desired output is produced from an output winding of the transformer by turning on and off the switching element.

Claims

1. A DC-DC converter comprising:

a first transformer including an input winding, an output winding, and a feedback winding;

a switching element for selectively connecting and disconnecting said input winding of said first transformer to a DC power supply;

a drive circuit including a second transformer which is connected to an input of said switching element to cause said switching element to effect on-off operation thereby to produce a desired output from said output winding of said first transformer;

a high impedance element connected between said DC power supply and said input terminal of said switching element;

an oscillation circuit for positively feeding back an output of said feedback winding of said transformer to said input terminal of said switching element to generate an oscillation to produce pulses with such a small duty raTio that the average value of the output voltage derived from said output winding of said first transformer due to the pulses is substantially zero; and

a rectifier circuit for rectifying an output voltage derived from said first transformer and for holding the rectified peak voltage to apply the rectified peak voltage to said drive circuit as an operating power source for said drive circuit.

2. A DC-DC converter according to claim 1, in which said first transformer is provided with an auxiliary winding in the same polarity as the input winding thereof so that the output from said auxiliary winding is applied to said rectifier circuit so as to be rectified.

3. A DC-DC converter according to claim 1, in which said input and output windings of said first transformer are arranged in the same polarity with each other so that the output from said output winding of said first transformer is applied to said rectifier circuit so as to be rectified.

4. A DC-DC converter having a first transformer, a switching element connected in series with an input winding of said first transformer, a DC power supply connected to the series circuit of said input winding of said first transformer and said switching element to make up a closed loop, a drive circuit including a second transformer for rendering said switching element to be turned on and off thereby to produce a desired output from an output winding of said first transformer, in which said converter further comprises an oscillation circuit for positively feeding back an output of a feedback winding of said first transformer to an input terminal of said switching element;

a first rectifier circuit for rectifying an output voltage with a low duty ratio produced from an auxiliary winding of said first transformer to produce a first rectified voltage, said auxiliary winding being arranged in the same polarity as the input winding of said first transformer;

means for applying said first rectified voltage to said drive circuit, said first rectified voltage being used as a first operating voltage for said drive circuit during the initial energization period;

a second rectifier circuit for rectifying the output voltage from said output winding of said first transformer to produce a second rectified voltage;

means for applying said second rectified voltage to said drive circuit, said second rectified voltage being used as a second operating voltage for said drive circuit during the normal operating period.

5. A DC-DC converter comprising a first transformer including an input winding, an output winding, and a feedback winding, a pair of switching elements connected to the end terminals of the input winding of said first transformer respectively, a DC power supply connected to the center point of said input winding of said first transformer, a drive circuit including a second transformer which is connected to an input of said switching elements to cause said switching elements to effect on-off operation so that the electric power from said DC power supply is converted into an AC power by the push-pull operation of said switching elements, an oscillation circuit for positively feeding back an output from the feedback winding of said first transformer to the input terminal of said switching elements to generate an oscillation to produce pulses with such a small duty ratio that the average value of the output voltage derived from said output winding of said first transformer is substantially zero, and a rectifier circuit for rectifying an output voltage derived from said first transformer and for holding the rectified peak voltage to apply the rectified peak voltage to the drive circuit as an operating power source for said drive circuit.

6. A bridge type DC-DC converter comprising first and second switch means each including a pair of series-connected switching elements, said first and second switch means being connected in parallel with each other, a DC power supply connected in series with said respective two switch means, a first transformer including an input winding, an output winding, and a feedback winding, said first transformer being inserted between said two switch means in a manner so that one end of an input winding of said first transformer being connected to a junction point of the pair of switching elements of said first switch means, the other end of the input winding of said first transformer being connected to a junction of the pair of switching elements of said second switch means, a drive circuit including a second transformer which is connected to an input of said switching elements to cause said switching elements to effect on-off operation, an oscillation circuit for feeding back the output from the feedback winding of said first transformer to the input terminal of said switching elements to generate an oscillation to produce pulses with such a small duty ratio that the average value of the output voltage derived from the output winding of said first transformer due to the pulses is substantially zero, and a rectifier circuit for rectifying an output voltage derived from said first transformer and for holding the rectified peak voltage to apply the rectified peak voltage to said drive circuit as an operating power source for said drive circuit.

7. A DC-DC converter comprising a first transformer including an input winding, an output winding, a feedback winding and an auxiliary winding separate from the output winding, a switching element connected in series with the input winding of said first transformer, a DC power supply connected to the series circuit of said first transformer and said switching element to make up a closed loop, a drive circuit including a second transformer for causing said switching element to effect on-off operation so as to produce a desired output from the output winding of said first transformer, an oscillation circuit for positively feeding back the output from the feedback winding of said first transformer to an input terminal of said switching element, and a rectifier circuit for rectifying the output voltage derived from the auxiliary winding of said first transformer and for applying the rectified voltage as an operating voltage for said drive circuit.