Power conversion efficiency using variable switching frequency
Power conversion efficiency using variable switching frequency. At least some of the example embodiments are power circuit controllers including a voltage sense input and a control signal output. The power circuit controller varies an output frequency of the control signal output between a first frequency and a second frequency based on a source voltage supplied to the power controller. Both the first frequency and the second frequency are non-zero.
1. A power circuit controller, comprising:
a voltage sense input;
a main switch output;
an active clamp switch output; and
the power circuit controller configured to:
sense a peak magnitude of a direct current (DC) voltage at the voltage sense input;
generate a main switch signal on the main switch output having an output frequency that varies between a first frequency and a second frequency based on the peak magnitude of the DC voltage at the voltage sense input, and wherein both the first frequency and the second frequency are non-zero; and
generate an active clamp signal on the active clamp switch output having the output frequency.
2. The power circuit controller of claim 1 , wherein the power circuit controller is configured to select the first frequency when the peak magnitude of the DC voltage indicates a low line voltage source, and the power circuit controller is configured to select the second frequency when the peak magnitude of the DC voltage indicates a high line voltage source.
3. The power circuit controller of claim 2 , wherein the first frequency is lower than the second frequency.
4. The power circuit controller of claim 2 , wherein the power circuit controller is programmed with a value of the first frequency and a value of the second frequency.
5. The power circuit controller of claim 1 , further including a voltage sensing circuit coupled between the voltage sense input and a circuit node of a power circuit.
6. The power circuit controller of claim 5 , wherein the voltage sensing circuit outputs a binary signal to the power circuit controller indicating whether the voltage sense input is coupled to a high line voltage or a low line voltage.
7. The power circuit controller of claim 1 , wherein the power circuit controller is configured to vary the output frequency proportionally to the peak magnitude of the DC voltage at the voltage sense input.
8. A power converter controller, comprising:
an input terminal;
a main switch terminal;
an active clamp terminal;
a secondary rectifier terminal; and
a controller integrated circuit configured to:
sense a value indicative of peak magnitude of a direct current (DC) voltage at the input terminal;
generate a main switch signal on the main switch terminal having an operating frequency that varies between a first non-zero frequency and a second non-zero frequency based on the value indicative of peak magnitude of the (DC) voltage at the input terminal;
generate an active clamp signal on the active clamp terminal having the operating frequency; and
generate a rectifier signal on the secondary rectifier terminal having the operating frequency.
9. The power converter controller of claim 8 , wherein the controller integrated circuit is configured to set the operating frequency at the first non-zero frequency when the value indicative of peak magnitude of the (DC) voltage indicates the input terminal is coupled to a low line voltage source, and the controller integrated circuit is configured to set the signal frequency at the second non-zero frequency when the value indicative of peak magnitude of the (DC) voltage indicates the input terminal is coupled to a high line voltage source, wherein the first non-zero frequency is lower than the second non-zero frequency.
10. The power converter controller of claim 8 , further including a voltage sensing circuit coupled between the input terminal and a circuit node of a power circuit.
11. The power converter controller of claim 8 , wherein the controller integrated circuit is configured to vary between the first non-zero frequency and the second non-zero frequency proportionally to the peak magnitude of the DC voltage at the input terminal.
12. The power converter controller of claim 8 , wherein the controller integrated circuit is configured to vary the operating frequency inversely proportional to load.
13. A power supply controller, comprising:
an input terminal;
a main switch terminal; and
a controller integrated circuit configured to:
sense an input voltage at the input terminal;
calculate a switching frequency that results in a peak-to-peak magnetizing current that is predetermined, wherein the switching frequency resides between and including a first frequency and a second frequency, and wherein the first frequency and the second frequency are non-zero; and
generate a main switch signal on the main switch terminal at the switching frequency.
14. The power supply controller of claim 13 , wherein the switching frequency is directly proportional to the input voltage.
15. The power supply controller of claim 13 , wherein the controller integrated circuit is programmed with a plurality of values of the switching frequency as a function of input voltage at the input terminal.