Electronic control system for efficient transfer of power through resonant circuits

• US 3,953,779 A
• Filed: 05/30/1974
• Issued: 04/27/1976
• Est. Priority Date: 05/30/1974
• Status: Expired due to Term

• Current Assignee: FRIJOUF, ROBERT F. (1/3%) INTEREST, SCHWARZ, RUTH INDIVIDUALLY (2/3%) INTEREST
• Original Assignee: Francisc Carol Schwarz
• Inventors: Schwarz, Francisc Carol
• Primary Examiner(s): Pellinen, A. D.
• Application Number:
  US05/474,788
• Time in Patent Office: 698 Days
• Field of Search: 321/2, 321/18, 321/19, 321/45 R, 321/45 ER
• US Class Current: 363/28
• CPC Class Codes: H02M 3/3155 with automatic control of the output voltage or current
• CPC Class Codes: H02M 7/4826 operating from a resonant DC source, i.e. the DC input voltage varies periodically, e.g. resonant DC-link inverters
• CPC Class Codes: H02M 7/5236 in a series push-pull arrangement

Abstract

A device to control the transfer of energy via resonant circuits from a D.C. source of electric energy to a load. The device confines the resonant currents to near the magnitude needed to accomplish this controlled transfer within prescribed limits, independent of variations of the source voltage or of the load. The voltage stresses imposed on the individual circuit components are contained accordingly. An electronic control system governs the electronic power switches to conform to a pattern of operation which confines the average currents in the resonant circuits to preset levels and therewith confines the series capacitor voltage amplitude to predictible and restricted magnitudes. The rms content of the resonant current is restricted to predictible and moderate deviations from a design norm for specified conditions of system operation.

Claims

1. A controllable converter device for providing electrical current to a load, comprising in combination:

a power source;

first and second switch means;

capacitor means;

a first series resonant circuit comprising said first switch means connected in series with the load and said capacitor means;

a second series resonant circuit comprising said second switch means connected in series with the load and said capacitor means;

means connecting said first and second resonant circuits across said power source;

control means enabling alternate conduction of said first and second switch means to provide alternate direction load current from said power source to the load during alternate charging of said capacitor means;

said alternate charging of said capacitor means providing alternate potentials which oppose said alternate conduction of said first and second switch means thereby alternately terminating conduction of said first and second switch means;

and means connected to said first and second series resonant circuit for enabling discharge of said capacitor means between said alternate direction load currents to limit the voltage of said capacitor means.

2. A converter as set forth in claim 1, wherein said means connected to said first and second series resonant circuits for enabling discharge of said capacitor means includes diode means.

3. A converter as set forth in claim 2, wherein said first and second switch means are unidirectional and said diode means includes a first and a second diode connected in an antiparallel configuration with said first and second unidirectional switch means, respectively.

4. A converter as set forth in claim 1, wherein said capacitor means includes a first and a second capacitor;

said first capacitor being connected in said first series resonant circuit,

said second capacitor being connected in said second series resonant circuit,

and said first and second capacitors being connected in series across said power source.

5. A converter as set forth in claim 1, wherein said switch means include thyristors.

6. A converter as set forth in claim 1, wherein said switch means includes a solid state device.

7. A converter as set forth in claim 1, wherein said control means includes means for determining the voltage on said capacitor means in accordance with the current flow thereto;

and means enabling the next alternate conduction of said first and second switch means when said voltage on said capacitor means is below a preselected voltage level.

8. A converter as set forth in claim 7, wherein said control means includes means for sensing the voltage across the load,

and means for varying said preselected voltage level in accordance with variations of said voltage across the load.

9. A converter as set forth in claim 1, wherein said capacitor means alternately charges to provide alternate potentials on said capacitor means to oppose said power source to alternately terminate conduction of said first and second switch means upon completion of approximately one-half cycle of resonant oscillation.

10. A converter as set forth in claim 1, wherein said means connected to said first and second series of resonant circuits for enabling discharge of said capacitor means to limit the voltage thereof includes reducing the voltage of said capacitor means.

11. A converter as set forth in claim 1, wherein said control means includes current sensor means for providing a current sensor output in accordance with the current flow relative to said capacitor means;

a current reference output;

means providing a summing output of said current sensor output and said current reference output;

integrator means for integrating said summing output;

and means receiving the output of said integrator means for activating conduction of said first and second switch means to substantially control the average current for an average cycle of oscillation.

12. A converter as set forth in claim 1, wherein said control means includes current sensor means for providing a current sensor output in accordance with the current flow to said capacitor means;

integrator means for integrating said current sensor output to determine the voltage on said capacitor means in accordance with the current flow thereto;

and means for enabling the next alternate conduction of said first and second switch means upon detecting a given signal level of said integrator means indicating that the voltage on said capacitor means is below a preselected voltage level.

13. A converter as set forth in claim 1, wherein said control means includes current sensor means for providing a current sensor output in accordance with the current flow to said capacitor means;

voltage sensor means for providing a voltage sensor output in accordance with the voltage across the load;

a summing device for providing a summing output from the combination of said current sensor output and said voltage sensor output;

integrator means for integrating said summing output to provide a signal in relation to the voltage on said capacitor means which is modified by variations in the voltage across the load;

a threshold sensor providing a threshold output upon detecting a given signal level of said integrator means indicating that the voltage on said capacitor means is below a preselected voltage level;

and bistable means responsive to said threshold output to alternately enable conduction of said first and second switch means upon a threshold output.

14. A controllable converter device for providing electrical current to a load, comprising in combination:

a power source;

a first and second pair of unidirectional switches;

a capacitor;

a first series resonant circuit comprising said first pair of switches connected in series with the load and said capacitor;

a second series resonant circuit comprising said second pair of switches connected in series with the load and said capacitor;

means connecting said first and second resonant circuits across said power source;

control means establishing alternate conduction of said first and second pairs of switches providing alternate direction load current from said power source to the load during alternate charging of said capacitor;

said alternate charging of said capacitor providing alternate potentials on said capacitor which oppose said alternate conduction of said first and second pairs of switches thereby alternately terminating conduction of said first and second pairs of switches;

and diode means connected to said first and second resonant circuits for enabling discharge of said capacitor between said alternate direction load current to limit the voltage applied to said capacitor.

15. A converter as set forth in claim 14, wherein said capacitor and the load are interposed between each pair of said first and second unidirectional switches.

16. A converter as set forth in claim 14 wherein said diode means connected to said first and second resonant circuits includes a first and a second pair of diodes respectively connected in an anti-parallel configuration with said first and second pair of unidirectional switches.