Active power factor corrector circuit
In accordance with an embodiment, an electronic device includes a controller configured to be coupled to a first switch of a power factor corrector. The controller is configured to produce a variable switching frequency depending on a load current. For a first load current, the controller is configured to produce a first switching frequency, and for a second load current, the controller is configured to produce a second switching frequency.
1. An electronic device comprising:
a controller configured to be coupled to a first switch of a power factor corrector, the controller configured to produce a variable switching frequency depending on a load current, the controller configured to produce a first switching frequency for a first load current and a second switching frequency for a second load current, wherein the controller further comprises
an estimator configured to determine a correction factor in accordance with an output signal of the device, and
a frequency evaluator coupled to the estimator, wherein the frequency evaluator is configured to determine a frequency in accordance with the correction factor and a peak input current.
2. The electronic device of claim 1 , wherein the controller is further configured to produce the switching frequency depending on a load voltage.
3. The electronic device of claim 2 , wherein a first load voltage is lower than a second load voltage, and the first switching frequency is lower than the second switching frequency.
4. The electronic device of claim 1 , wherein the first load current is higher than the second load current, and the first switching frequency is lower than the second switching frequency.
5. The electronic device of claim 4 , wherein the device further comprises:
a first switch coupled to the controller;
an inductor coupled to the first switch;
a second switch coupled to the inductor;
a capacitor coupled to the first switch;
a first diode coupled to the second switch;
a second diode coupled to the first diode;
a first voltage divider coupled to the first diode, and coupled to the controller; and
an AC input node.
6. The electronic device of claim 4 , further comprising:
a first switch coupled to the controller;
an inductor coupled to the first switch;
a diode coupled to the first switch;
a capacitor coupled to the first switch;
a first voltage divider coupled to the controller; and
a second voltage divider coupled to the controller.
7. The electronic device of claim 1 , wherein the frequency evaluator is further configured to determine the frequency based on an output voltage.
8. The electronic device of claim 1 , wherein the output signal comprises a current, a voltage or a power.
9. The electronic device of claim 1 , wherein the frequency evaluator comprises a look-up table.
10. The electronic device of claim 1 , wherein the frequency evaluator is configured to calculate the correction factor based on a formula.
11. The electronic device of claim 10 , wherein the frequency evaluator is further configured to calculate the correction factor based on a battery charging characteristic.
12. The electronic device of claim 1 , wherein the controller further comprises an oscillator having a frequency control input coupled to the frequency evaluator.
13. The electronic device of claim 12 , wherein the controller further comprises:
a latch having a first input coupled to the oscillator and an output configured to:
be coupled to a control node of the first switch; and
determine a second switch control signal from a comparator output signal and an output of the oscillator;
a comparator coupled to a second input of the latch; and
a reference current signal generator coupled to the comparator, wherein the reference current signal generator is configured to determine the reference current signal based on a voltage input.
14. A method of controlling a power factor corrector, the method comprising determining a switching frequency of the power factor corrector, comprising:
determining a load current; and
assigning a switching frequency based on the load current comprising
determining a correction factor in accordance with an output signal of the power factor corrector, and
determining the switching frequency in accordance with the correction factor and a peak input current.
15. The method of claim 14 , wherein a first switching frequency is lower than a second switching frequency and a first load current is higher than a second load current.
16. The method of claim 15 , further comprising determining a load voltage, wherein assigning the switching frequency further comprises assigning the switching frequency based on the load voltage.
17. The method of claim 16 , wherein a first switching frequency is lower than a second switching frequency and a first load voltage is lower than a second load voltage.
18. The method of claim 14 , further comprising controlling a switch coupled to an inductor of the power factor corrector at the determined switching frequency.
19. A circuit comprising:
a power factor corrector circuit comprising:
a controller configured to produce a switching frequency in accordance with a battery charging curve,
an estimator configured to determine a correction factor based on a signal of a DC output, the signal comprising a current, a voltage, or a power, and
a frequency evaluator coupled to the estimator, the frequency evaluator configured to determine the switching frequency based on the correction factor and a peak input current;
an AC input coupled to the power factor corrector circuit; and
the DC output coupled to the power factor corrector circuit.
20. The circuit of claim 19 , the power factor corrector circuit further comprising:
a switch coupled to the controller;
an inductor coupled to the switch;
a capacitor coupled to the switch; and
a voltage divider coupled between the inductor and a ground node, wherein an output voltage of the voltage divider is coupled to an input of the controller.
21. The circuit of claim 19 , wherein the controller further comprises:
an oscillator coupled to the frequency evaluator, and the oscillator is configured to provide an oscillator signal based on the frequency;
a latch having a first input coupled to the oscillator and an output configured to be coupled to a control node of a switch;
a comparator coupled to a second input of the latch; and
a reference current signal generator coupled to the comparator, the reference current signal generator configured to determine the reference current based on a voltage input.
22. The circuit of claim 19 , wherein the circuit is configured to charge a battery.
23. A method of controlling a power factor corrector, the method comprising determining a switching frequency of the power factor corrector, comprising:
determining a load current; and
assigning a switching frequency in accordance with the load current and a battery charging curve, wherein assigning the switching frequency further comprises
determining a correction factor in accordance with an output signal of the power factor corrector, and
determining the switching frequency in accordance with the correction factor and a peak input current.
24. The method of claim 23 , further comprising setting a DC output in accordance with the switching frequency.
25. The method of claim 24 , further comprising charging a battery with the DC output.
26. The method of claim 23 , further comprising charging a battery in accordance with the switching frequency.