Transformer isolated AC to DC power conditioner with resistive input current

• US 4,885,675 A
• Filed: 10/07/1988
• Issued: 12/05/1989
• Est. Priority Date: 10/07/1988
• Status: Expired due to Term

• Current Assignee: Unisys Corporation
• Original Assignee: Unisys Corporation
• Inventors: Smith, James A., Henze, Christopher P.
• Primary Examiner(s): Salce, Patrick R.
• Assistant Examiner(s): VOELTZ, EMANUEL T
• Application Number:
  US07/254,635
• Time in Patent Office: 424 Days
• Field of Search: 363/25, 363/26, 363/45, 363/46, 363/97, 363/131, 363/133, 323/205-211
• US Class Current: 363/26
• CPC Class Codes: H02M 1/4258 using a single converter stage both for correction of AC input power factor and generation of a regulated and galvanically isolated DC output voltage H02M1/4241 takes precedence
• CPC Class Codes: H02M 1/44 Circuits or arrangements for compensating for electromagnetic interference in converters or inverters
• CPC Class Codes: H02M 3/3378 in a push-pull configuration of the parallel type H02M3/3374 takes precedence
• 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

A single stage power conditioner which produces an isolated DC output while drawing resistive input current from the utility has been described. A high frequency switch-mode technique was used which operates in continuous conduction mode to reduce electro-magnetic interference (EMI) generation and ripple losses.

Claims

1. An AC to DC power conditioner comprising first and second switching means having first and second controllable current-path means and first and second control means, respectively, for controlling said first and second controllable current-path means, respectively, output transformer means comprising a center tapped primary winding having a first winding section of one polarity coupled in series with said first controllable current-path means and a second winding section of an opposite polarity coupled in series with said second controllable current-path means, inductance means coupled to the center tap of said primary winding and to a source of AC input voltage, pulse width modulation means coupled to supply first and second pulse width modulated control signals to said first and second control means, respectively, drive means for driving said pulse width modulation means as a function of an error signal, variable gain input voltage sense means and input current sense means for developing first and second signals which are combined to form said error signal, and which are respectively proportional to the instantaneous average input voltage and the instantaneous average input current to said power conditioner.

2. In the power conditioner of claim 1 wherein said pulse width modulation means provides pulses of a constant pulse repetition frequency.