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High efficiency DC to DC converter

  • US 4,129,788 A
  • Filed: 04/26/1977
  • Issued: 12/12/1978
  • Est. Priority Date: 04/26/1977
  • Status: Expired due to Term
First Claim
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1. A dual output, high efficiency, low output ripple DC to DC converter, comprisingan input section receiving a DC input and providing a substantially constant frequency AC output,a transformer having a primary winding receiving said AC output and having first and second secondary windings,a first rectifier connected to said first secondary winding and providing a first rectified output,a series inductance and parallel capacitance filter receiving said first rectified output and providing a smoothed first DC output,smoothing means for sensing said first rectified output and providing a first control signal corresponding thereto,a first regulator means for receiving said first rectified output and said first control signal and providing a feedback signal in response to said first control signal when said smoothed first DC output exceeds a predetermined reference level,means in said input section receiving said feedback signal and modulating the pulse width of said substantially constant frequency AC output in response thereto, so that said smoothed first DC output is maintained at a substantially constant voltage level while current demand from an applied load varies,a second rectifier connected to said second secondary winding providing a second rectified output,means for sensing said second rectified output and providing a second control signal which corresponds thereto and which is synchronized with said AC output,a series inductance and parallel capacitance filter receiving said second rectified output and providing a smoothed second DC output,a second regulator means for receiving said smoothed second DC output and said second control signal and providing a switching output in response thereto,an electronic switch connected with said second regulator means and being actuated by said switching output and operating to modulate the pulse width of said second rectified output, so that said smoothed second DC output is maintained at a substantially constant voltage level while current level demand from an applied electrical load varies,a series diode preload resistor circuit connected across said smoothed second DC output, said preload resistor circuit being coupled to said electronic switch and operating to provide driving current therefor when said switch is in the on condition and high load current is required at said smoothed second DC output, and to preload said second regulator means when said switch is in the off condition and low load current is required to said smoothed second DC output.

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