Power supply and power supply method with circulation current compensation
A power supply comprises an inverter leg adapted to generate a first pulse width modulation signal by modulating an input signal, a phase shifter, which is adapted to generate a provisional second pulse width modulation signal by phase shifting a signal from which the first pulse width modulation signal is derived, a compensator, which is adapted to determine a second pulse width modulation signal from the provisional second pulse width modulation signal and add a compensation signal during the generating of the second pulse width modulation signal, and a coupled inductor, which is adapted to combine the first pulse width modulation signal and the second pulse width modulation signal to form the output signal.
1. A power supply for generating an output signal, comprising:
an inverter leg configured to generate a first pulse width modulation signal by modulating an input signal with a modulation wave signal m(n), wherein n is a time index;
a phase shifter configured to generate a provisional second pulse width modulation signal by phase shifting the first pulse width modulation signal;
a compensator configured to determine a second pulse width modulation signal from the provisional second pulse width modulation signal by adding a compensation signal, wherein the compensation signal is based on the modulation wave signal m(n); and
a coupled inductor configured to combine the first pulse width modulation signal and the second pulse width modulation signal to form the output signal.
2. The power supply of claim 1 , wherein the second pulse width modulation signal compensates for a circulation current within the coupled inductor.
3. The power supply of claim 1 , wherein the modulation wave signal m(n) is an alternating current (AC) signal.
4. The power supply of claim 1 , wherein the compensation signal is based on the following equation:
Y= 2×Δ m,
wherein Y is the compensation signal, and wherein Δm is determined as m(n)−m(n−1).
5. The power supply of claim 4 , wherein the compensation signal is limited by a pre-specified maximum value.
6. The power supply of claim 1 , further comprising a rectifier configured to generate a direct current (DC) bus voltage by rectifying an alternating current (AC) input voltage.
7. The power supply of claim 1 , wherein the provisional second pulse width modulation signal has an identical duty cycle as the first pulse width modulation signal.
8. The power supply of claim 1 , further comprising a first switch, wherein the modulation wave signal m(n) is used to activate and deactivate the first switch.
9. The power supply of claim 1 , further comprising a second inverter leg separate from the inverter leg, wherein the second inverter leg comprises the phase shifter and the compensator.
10. The power supply of claim 9 , wherein the inverter leg comprises a pulse width modulator configured to generate the first pulse width modulation signal.
11. A method for generating an output signal, comprising:
generating a first pulse width modulation signal by modulating an input signal with a modulation wave signal m(n), wherein n is a time index;
determining a provisional second pulse width modulation signal by phase shifting the first pulse width modulation signal;
determining a second pulse width modulation signal from the provisional second pulse width modulation signal by adding a compensation signal, wherein the compensation signal is based on the modulation wave signal m(n); and
combining the first pulse width modulation signal and the second pulse width modulation signal to form the output signal.
12. The method of claim 11 , wherein the compensation signal compensates for a circulation current.
13. The method of claim 11 , wherein the modulation wave signal m(n) is an alternating current (AC) signal.
14. The method of claim 11 , wherein the compensation signal is determined using the equation:
Y= 2×Δ m,
wherein Y is the compensation signal, and wherein Δm is determined as m(n)−m(n−1).
15. The method of claim 14 , wherein the compensation signal is limited by a pre-specified maximum value.
16. The method of claim 11 , further comprising generating a direct current (DC) bus voltage by rectifying an alternating current (AC) input voltage.
17. The method of claim 11 , wherein the provisional second pulse width modulation signal has an identical duty cycle as the first pulse width modulation signal.
18. The method of claim 11 , wherein the provisional second pulse width modulation signal is determined by phase shifting the first pulse width modulation signal by 180 degrees.
19. The method of claim 11 , wherein adding the compensation signal comprises increasing a duty cycle of the provisional second pulse width modulation signal by the compensation signal.
20. The method of claim 11 , further comprising determining the second pulse width modulation signal by modulating the input signal with a second pulse width modulation control signal.