Electronic circuit comprising two static converters operating in a quasi-resonant zero-voltage switching mode and a method of operating such a circuit

1. A method of operating an electronic circuit ( 10 ), said circuit comprising two static converters (ConvM; ConvE), one of them being a master converter (ConvM) notably comprising a master PWM controller (M) and a switch (TM) and the other being a slave converter (ConvE) notably comprising a slave PWM controller (E) and a switch (TE), designed to step up an input voltage (Vin) of the circuit in order to deliver a higher output voltage (Vout), each of said converters having respective zero-voltage detection, and operating in a quasi-resonant mode by zero-voltage switching of their respective switch (TM; TE), the method comprising:

the master PWM controller (M) sends, when the switch (TM) of said master converter (ConvM) is turned on and when a preset phase-shift criterion is met, a control signal to the slave PWM controller C= which, in response to said control signal, turns off (OFF) the switch (TE) of said slave converter (ConvE);

the master PWM controller (M) and the slave PWM controller (E) turn on (ON) the respective switch (TM; TE) of their respective converter (ConvM; ConvE) as soon as a zero voltage (zvd) is detected across the terminals of said respective switch (TM; TE);

wherein a magnitude (Im) of an electric current in the switch TM of the master converter (ConvM) is measured, and the preset phase-shift criterion is met when said measured magnitude (Im) reaches a preset value.

2. The method as claimed in claim 1 , characterized in that the preset value is between one third and two thirds of a preset peak value (Imc) of said electric current in the switch (TM) of the master converter (ConvM).

3. The method as claimed in claim 1 , characterized in that the input voltage (Vin) of the electronic circuit ( 10 ) is filtered by means of a low-pass filter (F).

4. The method as claimed in claim 1 , characterized in that the master PWM controller (M) keeps the switch (TE) of the slave converter (ConvE) turned off, during a predefined operating phase of the circuit, as long as an output voltage (Vout) of the circuit exceeds a preset value.

5. The method as claimed in claim 2 , characterized in that the input voltage (Vin) of the electronic circuit ( 10 ) is filtered by means of a low-pass filter (F).

6. The method as claimed claim 2 , characterized in that the master PWM controller (M) keeps the switch (TE) of the slave converter (ConvE) turned off, during a predefined operating phase of the circuit, as long as an output voltage (Vout) of the circuit exceeds a preset value.

7. The method as claimed in claim 3 , characterized in that the master PWM controller (M) keeps the switch (TE) of the slave converter (ConvE) turned off, during a predefined operating phase of the circuit, as long as an output voltage (Vout) of the circuit exceeds a preset value.

8. An electronic circuit ( 10 ) comprising:

two static converters (ConvM; ConvE), one of them being a master converter (ConvM) notably comprising a master PWM controller (M) and a switch (TM) and the other being a slave converter (ConvE) notably comprising a slave PWM controller (E) and a switch (TE), designed to step up an input voltage (Vin) of the circuit in order to deliver a higher output voltage (Vout), each of said converters having respective zero-voltage detection, and operating in a quasi-resonant mode by zero-voltage switching of their respective switch (TM; TE), in which:

the master PWM controller (M) is configured to send, when the switch (TM) of said master converter (ConvM) turned on and when a preset phase-shift criterion is met, a control signal to the slave PWM controller (E), said slave PWM controller (E) being configured to turn off (OFF) the switch (TE) of said slave converter (ConvE) in response to said control signal;

the master PWM controller (M) and the slave PWM controller (E) are configured to turn on (ON) the respective switch (TM; TE) of their respective converter (ConvM; ConvE) as soon as a zero voltage (zvd) is detected across the terminals of said respective switch (TM; TE); and

means for measuring a magnitude (Im) of an electric current in the switch (TM) of the master converter (ConvM), wherein the preset phase-shift criterion is met when said measured magnitude (Im) reaches a preset value.

9. The electronic circuit as claimed in claim 8 , further comprising a low-pass filter (F) designed to filter the input voltage (Vin) of the circuit, said filter preferably comprising an inductor coil (Lfil) and two capacitors (Cfi 11 ; Cfi 12 ).

10. The electronic circuit as claimed in claim 8 , characterized in that the Master PWM controller (M) is configured to keep the switch (TE) of the slave converter (ConvE) turned off, during a predefined operating phase of the circuit, as long as the output voltage (Vout) of said circuit exceeds a preset value.

11. The electronic circuit as claimed in claim 8 , wherein the electronic circuit is utilized within a motor vehicle.

12. The electronic circuit as claimed in claim 9 characterized in that the Master PWM controller (M) is configured to keep the switch (TE) of the slave converter (ConvE) turned off, during a predefined operating phase of the circuit, as long as the output voltage (Vout) of said circuit exceeds a preset value.

13. The electronic circuit as claimed in claim 9 , wherein the electronic circuit is utilized within a motor vehicle.

14. The electronic circuit as claimed in claim 10 , wherein the electronic circuit is utilized within a motor vehicle.