Current balanced DC-to-DC converter
First Claim
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1. A DC-to-DC converter, comprising:
- oscillator means for providing a linear ramp voltage waveform;
pulse means connected to said oscillator means for providing a pair of pulse waveforms, each waveform having a pulse alternating with the other in a push-pull manner;
switch means including a pair of transistor switches, each having a control terminal for transitioning each of said transistor switches between its conducting and nonconducting state, said pair of transistor switches being connected in a push-pull configuration with said control terminals connected to receive one of said pair of pulse waveforms;
a means including a transformer having a primary winding and a secondary winding, said primary winding connected to said pair of transistor switches to form a primary circuit through which current pulses pass;
feedback means connected to said primary winding for sensing said current pulses therethrough, and including a filter whose bandpass characteristic is related to the frequency of any current imbalance associated with said pair of transistor switches to provide a high gain feedback signal to said oscillator means to change alternate ones of said linear ramp voltage waveform in response to any imbalance in current pulses; and
whereby current imbalance in said primary circuit due to any mismatch in the storage time or saturation voltage of said pair of transistor switches is minimized.
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Abstract
A novel feedback circuit for use in a DC-to-DC converter accurately adjusts the pulse width of the control pulses to a pair of switching transistors to minimize current imbalance. The switching transistors generate current pulses in the primary windings of a center tapped transformer. The feedback path senses the current pulses in the primary circuit of the transformer. A filter in the feedback path has a bandwidth centered at about the frequency of any current imbalance. The high gain, closed loop feedback path changes the slope of alternate linear ramp voltage pulses, and hence varies the pulse width of the pulses presented to the control terminals of the switching transistors.
94 Citations
7 Claims
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1. A DC-to-DC converter, comprising:
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oscillator means for providing a linear ramp voltage waveform; pulse means connected to said oscillator means for providing a pair of pulse waveforms, each waveform having a pulse alternating with the other in a push-pull manner; switch means including a pair of transistor switches, each having a control terminal for transitioning each of said transistor switches between its conducting and nonconducting state, said pair of transistor switches being connected in a push-pull configuration with said control terminals connected to receive one of said pair of pulse waveforms; a means including a transformer having a primary winding and a secondary winding, said primary winding connected to said pair of transistor switches to form a primary circuit through which current pulses pass; feedback means connected to said primary winding for sensing said current pulses therethrough, and including a filter whose bandpass characteristic is related to the frequency of any current imbalance associated with said pair of transistor switches to provide a high gain feedback signal to said oscillator means to change alternate ones of said linear ramp voltage waveform in response to any imbalance in current pulses; and whereby current imbalance in said primary circuit due to any mismatch in the storage time or saturation voltage of said pair of transistor switches is minimized. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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Specification