Multisource magnetic integration using a current source fed transformer structure with decoupled secondary windings

1. An automotive power system comprising:

a traction battery;

an auxiliary battery;

a matrix transformer including two separate cores, a primary winding wound around each of the cores, a first secondary winding wound around one of the cores, and a second secondary winding galvanically isolated from the first secondary winding and wound around the other of the cores;

circuitry configured to transfer power from an AC source to the primary winding, to transfer power from the first secondary winding to the traction battery, and to transfer power from the second secondary winding to the auxiliary battery, wherein the circuitry includes a first active bridge having a switching frequency range, and a pair of series connected capacitors and an inductor center tapping the capacitors to form a capacitor-inductor-capacitor resonant network electrically connected between the first active bridge and primary winding and tuned to have a resonant frequency defined by the switching frequency range; and

a controller configured to operate the first active bridge to maintain a magnitude of current through the primary winding constant independent of load variation at the first and second secondary windings.

2. The automotive power system of claim 1 , wherein the circuitry includes a second active bridge, a DC output filter capacitor, and matching network circuitry configured to match an output impedance of the matrix transformer to an input impedance of the second active bridge.

3. The automotive power system of claim 2 , wherein the circuitry includes a third active bridge, a resonant capacitor, and an inductor-capacitor low pass filter configured to match an output impedance of the third active bridge to an input impedance of the inductor-capacitor low pass filter, wherein the third active bridge is a center tapped active bridge, and wherein the resonant capacitor is electrically connected in parallel with the inductor-capacitor low pass filter at a center tap of the center tapped active bridge such that under zero load conditions at the second secondary winding, current through the second secondary winding and the center tapped active bridge is greater than zero to permit the controller to maintain the magnitude of current through the primary winding constant independent of load variation at the first and second secondary windings.

4. The automotive power system of claim 3 , wherein the resonant capacitor is tuned to resonate with the inductor-capacitor low pass filter such that a load impedance of the third active bridge is capacitive during operation of the third active bridge within the switching frequency range.

5. The automotive power system of claim 3 , wherein the controller is further configured to operate the second and third active bridges such that a delay time between pulse width modulated gate signals of the second active bridge and pulse width modulated gate signals of the first active bridge is independent of a delay time between pulse width modulated gate signals of the third active bridge and the pulse width modulated gate signals of the first active bridge.

6. The automotive power system of claim 1 , wherein the circuitry further includes a bidirectional inverter, and a DC link capacitor between the bidirectional inverter and first active bridge.

7. An automotive power system comprising:

a traction battery;

an auxiliary battery;

a matrix transformer including two separate cores, a primary winding wound around each of the cores, a first secondary winding wound around one of the cores, and a second secondary winding galvanically isolated from the first secondary winding and wound around the other of the cores;

primary circuitry configured to transfer power from an AC source to the primary winding;

first secondary circuitry configured to transfer power from the first secondary winding to the traction battery; and

second secondary circuitry including a center tapped active bridge, a resonant capacitor, and an inductor-capacitor low pass filter configured to match an output impedance of the center tapped active bridge to an input impedance of the inductor-capacitor low pass filter, wherein the second secondary circuitry is configured to transfer power from the second secondary winding to the auxiliary battery, and wherein the resonant capacitor is electrically connected in parallel with the inductor-capacitor low pass filter at a center tap of the center tapped active bridge such that under zero load conditions at the second secondary winding, current through the second secondary winding and the center tapped active bridge is greater than zero.

8. The automotive power system of claim 7 , wherein the primary circuitry includes a bidirectional inverter, a first active bridge having a switching frequency range, a DC link capacitor between the bidirectional inverter and first active bridge, and a pair of series connected capacitors and an inductor center tapping the capacitors to form a capacitor-inductor-capacitor resonant network electrically connected between the first active bridge and primary winding and tuned to have a resonant frequency defined by the switching frequency range, further comprising a controller configured to operate the first active bridge to maintain a magnitude of current through the primary winding constant independent of load variation at the first and second secondary windings.

9. The automotive power system of claim 8 , wherein the resonant capacitor is tuned to resonate with the inductor-capacitor low pass filter such that a load impedance of the center tapped active bridge is capacitive during operation of the center tapped active bridge within the switching frequency range.

10. The automotive power system of claim 8 , wherein the first secondary circuitry includes a second active bridge, a DC output filter capacitor, and matching network circuitry configured to match an output impedance of the matrix transformer to an input impedance of the second active bridge.

11. The automotive power system of claim 10 , wherein the controller is further configured to operate the second active bridge and center tapped active bridge such that a delay time between pulse width modulated gate signals of the second active bridge and pulse width modulated gate signals of the first active bridge is independent of a delay time between pulse width modulated gate signals of the center tapped active bridge and the pulse width modulated gate signals of the first active bridge.

12. An automotive power system comprising:

a traction battery;

an auxiliary battery;

a matrix transformer including two separate cores, a primary winding wound around each of the cores, a first secondary winding wound around one of the cores, and a second secondary winding galvanically isolated from the first secondary winding and wound around the other of the cores;

circuitry, configured to transfer power from an AC source to the primary winding, including a bidirectional inverter, a first active bridge having a switching frequency range, a DC link capacitor between the bidirectional inverter and first active bridge, and a pair of series connected capacitors and an inductor center tapping the capacitors to form a capacitor-inductor-capacitor resonant network electrically connected between the first active bridge and primary winding and tuned to have a resonant frequency defined by the switching frequency range;

a controller configured to operate the first active bridge to maintain a magnitude of current through the primary winding constant independent of load variation at the first and second secondary windings;

circuitry, configured to transfer power from the first secondary winding to the traction battery, including a second active bridge, a DC output filter capacitor, and matching network circuitry configured to match an output impedance of the matrix transformer to an input impedance of the second active bridge; and

circuitry, configured to transfer power from the second secondary winding to the auxiliary battery, including a third active bridge, a resonant capacitor, and an inductor-capacitor low pass filter configured to match an output impedance of the third active bridge to an input impedance of the inductor-capacitor low pass filter, wherein the third active bridge is a center tapped active bridge, and wherein the resonant capacitor is electrically connected in parallel with the inductor-capacitor low pass filter at a center tap of the center tapped active bridge such that under zero load conditions at the second secondary winding, current through the second secondary winding and the center tapped active bridge is greater than zero to permit the controller to maintain the magnitude of current through the primary winding constant independent of load variation at the first and second secondary windings.

13. The automotive power system of claim 12 , wherein the resonant capacitor is tuned to resonate with the inductor-capacitor low pass filter such that a load impedance of the third active bridge is capacitive during operation of the third active bridge within the switching frequency range.

14. The automotive power system of claim 12 , wherein the controller is further configured to operate the second and third active bridges such that a delay time between pulse width modulated gate signals of the second active bridge and pulse width modulated gate signals of the first active bridge is independent of a delay time between pulse width modulated gate signals of the third active bridge and the pulse width modulated gate signals of the first active bridge.