System and method to control a resonant power converter

Patent metadata

Field	Value
Publication number	US-10917017-B1
Application number	US-201916717195-A
Country	US
Kind code	B1
Filing date	Dec 17, 2019
Priority date	Dec 17, 2019
Publication date	Feb 9, 2021
Grant date	Feb 9, 2021

Abstract

A resonant power converter includes a full bridge configuration of switching devices and a resonant tank circuit coupled between the full bridge and an isolation transformer having a primary winding and a secondary winding. A full bridge rectifier is coupled between the isolation transformer and a load. A converter controller for generating switching signals for the switching devices includes an outer controller to generate a tank command signal based on a voltage error signal between an output voltage command signal and an actual output voltage signal and an inner controller to generate an actual tank signal based on a secondary winding current and the output voltage command signal. The converter controller also includes a signal generator for generating the switching signals for the switching devices based on a tank error signal between the tank command signal and the actual tank signal.

First claim

The invention claimed is:

1. A resonant power supply, comprising:
a resonant power converter configured to convert an input direct current (DC) voltage to an output DC voltage, wherein the resonant power converter comprises:
a full bridge configuration of switching devices for converting the input DC voltage to a first alternating current (AC) voltage;
a resonant tank circuit having a resonant inductor and a resonant capacitor coupled between the full bridge configuration of switching devices and an isolation transformer having a primary winding and a secondary winding, wherein the isolation transformer converts the first AC voltage to a second AC voltage;
a full bridge rectifier for converting the second AC voltage to the output DC voltage;

a converter controller coupled to the resonant power converter for generating switching signals for the switching devices, the converter controller comprising:
an outer controller to generate a tank command signal based on a voltage error signal between an output voltage command signal and an actual output voltage signal;
an inner controller to generate an actual tank signal based on a secondary winding current and the output voltage command signal; and
a signal generator for generating the switching signals for the switching devices based on a tank error signal between the tank command signal and the actual tank signal.

2. The resonant power supply of claim 1 , wherein the outer controller comprises a proportional-integrator (PI) controller to receive the voltage error signal and a signal limiter which limits an output signal of the PI controller and generates the tank command signal.

3. The resonant power supply of claim 1 , wherein the inner controller comprises a primary voltage calculator, a resonant capacitor voltage calculator and a resonant inductor current calculator.

4. The resonant power supply of claim 3 , wherein the primary voltage calculator includes a switching module that determines a primary winding voltage by switching between the output voltage command signal and an inverted output voltage command signal based on one of the switching signals.

5. The resonant power supply of claim 4 , wherein the resonant capacitor voltage calculator includes an integrator module for determining a resonant capacitor voltage by integrating the secondary winding current signal and multiplying an integral signal of the integrator with a first constant equal to N/Cr, where Cr is a capacitance value of the resonant capacitor and N is a transformer winding turns ratio.

6. The resonant power supply of claim 5 , wherein the resonant inductor current calculator determines the resonant inductor current by multiplying the secondary winding current with a second constant equal to N.

7. The resonant power supply of claim 6 , wherein the inner controller comprises a second absolute value calculation block for determining a second absolute value of a signal Z 0 *I Lr , wherein Z 0 is a characteristic impedance of the resonant inductor and I Lr is the resonant inductor current.

8. The resonant power supply of claim 7 , wherein the inner controller further comprises a first absolute value calculation block for determining a first absolute value of a signal Vpri+Vcr, wherein Vpri is the primary winding voltage and Vcr is the resonant capacitor voltage.

9. The resonant power supply of claim 8 , wherein the inner controller includes a first summation block for adding the first absolute value and the second absolute value to provide the actual tank signal.

10. The resonant power supply of claim 7 , wherein the second absolute value signal is multiplied by a first fraction value to determine an absolute value control signal.

11. The resonant power supply of claim 10 , wherein the inner controller includes a first square function block and a second square function block to determine square values of signals Vpri+Vcr and Z 0 *I Lr respectively.

12. The resonant power supply of claim 11 , wherein the inner controller includes a multiplier to multiply the square value of signal Z 0 *I Lr with a second fraction value.

13. The resonant power supply of claim 12 , wherein the inner controller includes a square root function block to determine a square root value of a summation of output signals of the first square function block and the multiplier to provide a square root value control signal.

14. The resonant power supply of claim 13 , wherein the inner controller determines the actual tank signal based on summation of the absolute value control signal and the square root value control signal.

15. The resonant power supply of claim 14 , wherein the first fraction is α and the second fraction is (1−α) and wherein α is a predetermined value in the range from 0 to 1.

16. A method for controlling a resonant power supply, the resonant power supply comprising a full-bridge configuration of switching devices, a resonant tank circuit having a resonant inductor and a resonant capacitor and an isolation transformer having a primary winding and a secondary winding, the resonant tank circuit coupled between the full-bridge configuration and the isolation transformer, the method comprising:
generating a tank command signal based on a voltage error signal between an output voltage command signal and an actual output voltage signal of the resonant power supply;
generating an actual tank signal based on a secondary winding current and the output voltage command signal; and
generating switching signals for the switching devices based on a tank error signal between the tank command signal and the actual tank signal.

17. The method of claim 16 , wherein generating the tank command signal comprises utilizing a proportional integral (PI) controller for the voltage error signal.

18. The method of claim 17 , wherein the actual tank signal is determined based on a summation of a first absolute value of a signal Vpri+Vcr and a second absolute value of a signal Z 0 *T Lr , wherein Z 0 is a characteristic impedance of the resonant inductor, I Lr is a resonant inductor current, Vpri is a primary winding voltage and Vcr is a resonant capacitor voltage.

19. The method of claim 18 , wherein the resonant capacitor voltage is determined by integrating a secondary winding current signal by an integrator and multiplying an integral signal of the integrator with a first constant equal to N/Cr, where Cr is a capacitance value of the resonant capacitor and N is a transformer winding turns ratio.

20. The method of claim 19 , wherein the primary winding voltage is determined by switching between the output voltage command signal and an inverted output voltage command signal based on one of the switching signals.

21. The method of claim 20 , wherein the resonant inductor current is determined by multiplying the secondary winding current with a second constant equal to N.

Assignees

• Ge Prec Healthcare Llc
• Ge Prec Healthcare

Inventors

• Mcfarland Thomas G
• Aasen Eric

Classifications

• H02M3/3376 Primary

  with automatic control of output voltage or current · CPC title

• H02M3/33507 Primary

  with automatic control of the output voltage or current, e.g. flyback converters (H02M3/33561, H02M3/33569 take precedence) · CPC title

• H02M3/33573

  Full-bridge at primary side of an isolation transformer · CPC title

• H02M3/01

  Resonant DC/DC converters · CPC title

• Y02B70/10

  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 · CPC title