Digital power supply
Provided is an apparatus and method for a digital power supply that can provide independent power control, and control variable power, for two or more electrical loads. Disclosed embodiments may reduce the magnitude of harmonic currents and/or flicker introduced into a power system. Embodiments include a microprocessor that delivers power to electric loads using phase-controlled AC current. The microprocessor may calculate a power array corresponding to a requested power for each electric load. Logic is provided for populating the power array in a pattern that reduces the magnitude of harmonic currents and flicker.
1. A method of delivering power, comprising the steps of:
using one or more user input devices to select a first and second power setting for a first and second heating element, respectively;
electronically communicating the power settings to a microprocessor and using the microprocessor to calculate a total amount of power requested;
using the microprocessor to populate, and store in a memory, a first and second power array corresponding to the first and second heating element, respectively;
using the microprocessor to calculate a first and second phase angle array corresponding to the first and second power array;
causing the microprocessor to receive a zero crossing signal from a zero crossing detection unit; and
for a first time period, activating a first triac to deliver a phase-controlled AC wave pattern comprising phase-controlled AC wave cycles corresponding to the first phase angle array to the first heating element and delivering a phase-controlled AC wave pattern comprising phase-controlled AC wave cycles corresponding to the second phase angle array to the second heating element.
2. The method of claim 1 , further comprising the step of:
for a second time period, activating a second triac to deliver a phase-controlled AC wave pattern represented by the first phase angle array to the second heating element and delivering a phase controlled AC wave pattern represented by the second phase angle array to the first heating element.
3. The method of claim 2 ; wherein each power array contains four cells.
4. The method of claim 3 ; wherein the step of using the microprocessor to populate a first and second power array further comprises the steps of:
populating a first cell of the first power array with the same value as a third cell of the first power array;
populating a second cell of the first power array with the same value as a fourth cell of the first power array;
populating a first cell of the second power array with the same value as a third cell of the second power array; and
populating a second cell of the second power array with the same value as a fourth cell of the second power array.
5. The method of claim 4 , wherein each cell of each power array represents a power percentage and ranges from 0≤x≤1.0.
6. The method of claim 5 , wherein every alternate cell in the first power array is populated with a “0” or a “1”.
7. The method of claim 6 , wherein every alternate cell in the second power array is populated with a “0” or a “1”.
8. The method of claim 5 , wherein the first and second phase angle arrays are calculated using the microprocessor to apply the equation angle=arccos(2x−1) to the first and second power array, respectively.
9. The method of claim 5 , where in the first time period is calculated as a ratio of the first power setting to the total amount of power requested and the second time period is calculated as a ratio of the second power setting to the total amount of power requested.
10. The method of claim 5 , wherein the step of delivering power further comprises the step of activating a triac connected to the heating element.