Full bridge power converter with multiple zero voltage resonant transition switching

• US 4,953,068 A
• Filed: 11/08/1989
• Issued: 08/28/1990
• Est. Priority Date: 11/08/1989
• Status: Expired due to Term

• Current Assignee: Unisys Corporation
• Original Assignee: Unisys Corporation
• Inventors: Henze, Christopher P.
• Primary Examiner(s): Wong, Peter S.
• Application Number:
  US07/433,299
• Time in Patent Office: 293 Days
• Field of Search: 363/17, 363/41, 363/97, 363/98, 363/127, 363/132
• US Class Current: 363/17
• CPC Class Codes: H02M 3/33584 Bidirectional converters
• CPC Class Codes: H02M 3/3376 with automatic control of output voltage or current
• 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 full bridge switching power converter employs zero-voltage, resonant-transition (ZVRT) switching techniques which appreciably reduces the switching losses at high switching frequencies, (for example, 1 MHz and above), using constant frequency, pulse-width-modulation techniques. The converter is implemented using a transfer with four switching FET'"'"'s coupled to the primary of the transformer and four switching FET'"'"'s coupled to the output of the transformer and a control unit that supplies the constant waveforms necessary to achieve synchronization and timing required to achieve the ZVRT switching.

Claims

1. A full bridge power converter constructed to achieve substantially zero voltage, resonant transition switching comprising first and second input lines for receiving an input voltage;

first and second output lines for supplying an output voltage;

transformer means comprising an input winding with first and second primary lines and an output winding with first and second secondary lines;

first, second, third, fourth, fifth, sixth, seventh and eighth current-switching means, each comprising a current path and a control terminal for controlling the opening and closing said current path, each current-switching means being constructed to provide capacitance across said current path and a diode means that has an anode and a cathode coupled across said capacitance means;

output inductance means coupled to one of said output lines for coupling output load current that varies continuously between a first peak of one polarity and a second peak of a polarity opposite to said one polarity thereto; and

control means coupled to all of said control terminals for supplying control signals thereto, wherein,

said first current-switching means is connected so that its current path is coupled between said first input line and said first primary line such that its diode has its cathode coupled to said first input line and its anode is coupled to said first primary line,

said second current-switching means is connected so that its current path is coupled between said first primary line and said second input line such that its diode has its cathode coupled to said first primary line and its anode is coupled to said second input line,

said third current-switching means is connected so that its current path is coupled between said first input line and said second primary line such that its diode has its cathode coupled to said first input line and its anode is coupled to said second primary line,

said fourth current-switching means is connected so that its current path is coupled between said second primary line and said second input line such that its diode has its cathode coupled to said second primary line and its anode is coupled to said second input line,

said fifth current-switching means is connected so that its current path is coupled between said first output line and said first secondary line such that its diode has its cathode coupled to said first secondary line and its anode is coupled to said first secondary line,

said sixth current-switching means is connected so that its current path is coupled between said first secondary line and said second output line such that its cathode is coupled to said first secondary line and its anode is coupled to said second output line,

said seventh current-switching means is connected so that its current path is coupled between said first output line and said second secondary line such that its cathode is coupled to said first output line and its anode is coupled to said second secondary line,

said eighth current-switching means is connected so that its current path is coupled between said second secondary line and said second output line such that its cathode is coupled to said second secondary line and its anode is coupled to said second output line,

said input voltage comprises repetitive cyclic pattern of tri-level pulses in which said tri-level pulses comprise first, second and third levels of voltage that are controlled such that said second level is intermediate said first and third levels and each cycle of said pattern of said tri-level pulses follows the sequence of a first level of voltage, a second level of voltage, a third level of voltage and a second level of voltage, and

wherein said control means supplies control pulses to said control terminals of said current-switching means for controlling said current-switching means for each cycle of said pattern of said pulses so that when;

said input voltage is at an initial first level during a cycle said current paths of said first, fourth, fifth and eighth current-switching means are closed and said current paths of all of said other current-switching means are open, and when,

said input voltage goes to said second level during a cycle, said current paths of said second, fourth, fifth, sixth, seventh and eighth current-switching means are closed and all of said other current-switching means are open, wherein said current path of said first current-switching means is switched and open when said output current reaches said first peak before said current paths of said second, sixth and seventh current-switching means are switched closed, and when

said input voltage goes to said third level during a cycle, said current paths of said second, third, sixth and seventh current-switching means are closed, and all of said other current-switching means are open, wherein said current path of said second current-switching means is switched open when said output current reaches said first peak before said current paths of said first, fifth and eighth current switching means are switched closed,, and when

said input voltage goes again to said second level during a cycle, said current paths of said first, third, fifth, sixth, seventh and eighth current-switching means are closed and all of said other current-switching means are open, and when

said input voltage goes back to said initial first level to complete an input voltage cycle said current paths of said third, sixth and seventh current-switching means are switched open when said output current reaches said second peak before said fourth switching means is switched closed.

2. A full bridge power converter as claimed in claim 1 wherein said first input voltage level is of one polarity, said second voltage level is substantially a zero voltage level, and said third voltage level is of the opposite polarity to said one polarity and is of a substantially equal magnitude.