Method and circuit configuration for increasing the efficiency of resonant converter power supply circuits

• US 5,032,972 A
• Filed: 11/07/1989
• Issued: 07/16/1991
• Est. Priority Date: 11/07/1988
• Status: Expired due to Fees

• Current Assignee: Siemens AG
• Original Assignee: Siemens AG
• Inventors: Erckert, Ricardo
• Primary Examiner(s): BEHA JR, WILLIAM
• Application Number:
  US07/433,672
• Time in Patent Office: 616 Days
• Field of Search: 363/16, 363/20, 363/21, 363/97, 363/131
• US Class Current: 363/97
• CPC Class Codes: H03K 17/133 in field-effect transistor switches
• CPC Class Codes: H03K 17/6871 the output circuit comprising more than one controlled field-effect transistor

Abstract

A method and circuit configuration for closed-loop control of trigger signals of switching transistors in a resonant converter power supply circuit element having closed-loop control dependent on a zero crossing recognition, wherein a prematurely responding zero crossing detector is provided, includes comparing a period of time between the generation of a trigger signal and the switching of a power transistor with a time interval between a premature response of a zero crossing detector and an actual zero crossing. This is done in order to obtain a closed-loop control signal for controlling a deviation action threshold of the zero crossing detector.

Claims

1. Method for closed-loop control of trigger signals of switching transistors in a resonant converter power supply circuit element having closed-loop control dependent on a zero crossing recognition, wherein a prematurely responding zero crossing detector is provided, which comprises generating with a switched constant current source and a capacitor an electrical value being proportional with a period of time between generation of a trigger signal and switching of the power transistor, generating with a voltage comparator an electrical value being proportional with a time duration between a premature response of the zero crossing detector and the actual zero crossing, comparing the electrical value being proportional with the period of time between the generation of the trigger signal and the switching of the power transistor with the electrical value being proportional with the time interval between the premature response of the zero crossing detector and the actual zero crossing, obtaining a closed-loop control signal for controlling a deviation action threshold of the zero crossing detector, and ascertaining the actual zero crossing with a zero crossing detector without deviation action, and enabling the trigger signals with a zero crossing detector having deviation action.

2. Method according to claim 1, which comprises operating the resonant converter power supply circuit element by the zero current switch method.

3. Method according to claim 1, which comprises operating the resonant converter power supply circuit element by the zero voltage switch method.

4. Method according to claim 1, which comprises operating the resonant converter power supply circuit element by the single-phase method.

5. Method according to claim 1, which comprises operating the resonant converter power supply circuit element by the push-pull method.

6. In a resonant converter power supply circuit element having a switching transistor and closed-loop control dependent on a zero crossing recognition, a circuit configuration for closed-loop control of trigger signals for the switching transistor, comprising a prematurely responding zero crossing detector having deviation action, an output and a deviation action threshold, a zero crossing detector without deviation action having an output;

a first RS flip-flop triggered at rising edges and a second edge-triggered RS flip-flop each having setting and resetting inputs and an output;

at least one driver stage having a trigger signal acting upon the setting input of said first RS flip-flop, said at least one driver stage triggering the switching transistor, said first RS flip-flop being reset as a function of the switching state of the switching transistor; and

a time comparison stage having two inputs and an output, the output of said first RS flip-flop being connected to one of the inputs of said time comparison stage;

the output of said zero crossing detector having deviation action being connected to the setting input of said second RS flip-flop;

the output of said zero crossing detector without deviation action being connected to the resetting input of said second RS flip-flop; and

the output of said second RS flip-flop being connected to another of the inputs of said time comparison stage;

the output of said time comparison stage providing an outcome of a comparison of the signal duration of output signals of said first and second RS flip-flops for controlling the deviation action threshold of the zero crossing detector having deviation action.

7. Circuit configuration according to claim 6, wherein said time comparison stage is formed of a capacitor, a switchable current source for charging said capacitor, and a switchable current sink for discharging said capacitor;

said current source has a control input forming one of the inputs of said time comparison stage and said current sink has a control input forming the other input of said time comparison stage; and

said time comparison stage has an output variable being the instantaneous voltage value present across said capacitor.