Improving load transient response by adjusting reference current in isolated power converters

1. A power converter comprising:

an isolation barrier having a primary stage side and a secondary stage side;

a step-up converter positioned on said primary stage side, said step-up converter configured to condition an input voltage and generate a direct current (DC) boost voltage;

a DC capacitor coupled to an output of said step-up converter; and

a primary stage controller positioned on said primary stage side and coupled to said step-up converter, said primary stage controller configured to adjust a step-up converter reference voltage based on a load current signal indicative of a load transient, the load current signal transmitted from a secondary stage side of said isolation barrier, said primary stage controller configured to momentarily adjust an input current reference such that a charge rate of said DC capacitor increases to enable said power converter to provide sufficient power during the load transient.

2. The converter of claim 1 , wherein said step-up converter comprises one of a boost circuit and a power factor correction (PFC) circuit.

3. The converter of claim 1 , further comprising a secondary stage controller coupled to a step-down converter on said secondary stage side, said step-down converter coupled to an output of said step-up converter, said secondary stage controller configured to measure a load current provided to a load by said step-down converter and transmit the load current signal to said primary stage controller.

4. The converter of claim 3 , further comprising an optocoupler configured to enable communication between said primary and secondary stage sides across said isolation barrier.

5. The converter of claim 1 , wherein said DC capacitor is coupled across a DC link between said primary and secondary stage sides.

6. The converter of claim 1 , wherein said primary stage controller increases in bandwidth during the load transient to increase a response time of said primary stage controller.

7. A method comprising:

electrically isolating a primary stage and a secondary stage of a power conversion system using an isolation barrier;

adjusting, by a primary stage controller positioned in the primary stage, a step-up converter reference voltage based on a load current signal indicative of a load transient, the load current signal transmitted from the secondary stage; and

momentarily adjusting an input current reference such that a charge rate of said DC capacitor increases to enable said power converter to provide sufficient power during the load transient.

8. The method of claim 7 , further comprising:

measuring, by a secondary stage controller positioned in the secondary stage, a load current provided to a load by a step-down converter; and

transmitting the load current signal to the primary stage controller.

9. The method of claim 8 , wherein transmitting the load current signal to the primary stage controller further comprises transmitting the load current signal to the primary stage controller across the isolation barrier via an optocoupler.

10. The method of claim 8 , wherein transmitting the load current signal to the primary stage controller further comprises one of continuously transmitting the load current signal and transmitting the load current signal when a change the measured load current exceeds a predetermined threshold.

11. A power conversion system comprising:

a primary stage and a secondary stage;

a DC capacitor coupled across a DC link between the primary stage and the secondary stage;

an isolation barrier electrically isolating the primary stage and the secondary stage; and

a primary stage controller positioned in the primary stage, said primary stage controller configured to adjust a step-up converter reference voltage based on a load current signal indicative of a load transient, the load current signal transmitted from the secondary stage, wherein to adjust the step-up converter reference voltage, said primary stage controller is further configured to momentarily adjust an input current reference such that a charge rate of said DC capacitor increases to enable said power converter to provide sufficient power during the load transient.

12. The system of claim 11 , further comprising a step-up converter communicatively coupled to said primary stage controller in the primary stage, said step-up converter configured to condition an input voltage and generate a direct current (DC) boost voltage.

13. The system of claim 12 , wherein said step-up converter comprises one of a boost circuit and a power factor correction (PFC) circuit.

14. The system of claim 12 , further comprising:

a step-down converter positioned in the secondary stage, said step-down converter configured to condition the DC boost voltage to generate a DC output voltage for use by a load; and

a secondary stage controller communicatively coupled to said step-down converter, said secondary stage controller configured to measure a load current provided to the load by said step-down converter and transmit the load current signal to said primary stage controller.

15. The system of claim 14 , wherein said step-down converter comprises one of a buck converter and an inductor-inductor-capacitor (LLC) converter.

16. The system of claim 12 , further comprising an optocoupler configured to enable communication between said primary and secondary stages across said isolation barrier.

17. The system of claim 11 , wherein said primary stage controller increases in bandwidth during the load transient to increase a response time of said primary stage controller.