Control circuit of power converter and method for maximum power point tracking

• US 9,257,896 B1
• Filed: 01/11/2015
• Issued: 02/09/2016
• Est. Priority Date: 11/28/2014
• Status: Active Grant

• Current Assignee: Industrial Technology Research Institute
• Original Assignee: Industrial Technology Research Institute
• Inventors: Chen, Chien-Yu, Shih, Horng-Jzer, Chen, Tsan-Huang, Yeh, Bo-Ting
• Primary Examiner(s): Dole, Timothy J
• Assistant Examiner(s): AHMED, YUSEF A
• Application Number:
  US14/594,164
• Time in Patent Office: 394 Days
• US Class Current: 1/1
• CPC Class Codes: G05F 1/67 to the maximum power available from a generator, e.g. from solar cell
• CPC Class Codes: H02M 1/14 Arrangements for reducing ripples from dc input or output
• CPC Class Codes: H02M 3/04 by static converters
• CPC Class Codes: H02M 7/44 by static converters

Abstract

A control circuit of a power converter including a first and a second control modules is provided. The first control module sets sampling points for a ripple signal of an input voltage according to a reference signal. The first control module determines whether a power point is the maximum power point according to ripple voltages of the sampling points. The second control module controls the power converter to output a maximum power according to the maximum power point based on the determination result of the first control module and the reference signal. An embodiment of a method for tracking a maximum power point is provided. The input voltage of the power converter is measured. The sampling points are set for the ripple signal of the input voltage and phase information of the ripple signal is determined, such that the maximum power point is determined by using the ripple voltages.

Claims

1. A control circuit of a power converter, the control circuit comprising:

a first control module, setting a plurality of sampling points for a ripple signal of an input voltage of the power converter according to a reference signal, determining phase information of the ripple signal, and determining whether a power point of an energy generating system is a maximum power point according to a plurality of ripple voltages corresponding to the sampling points; and

a second control module, electrically connected to the first control module, and controlling the power converter to output a maximum power according to the maximum power point based on a determination result of the first control module and the reference signal, wherein the ripple voltages comprise a first ripple voltage and a second ripple voltage, and when the first ripple voltage is equal to the second ripple voltage, the first control module determines the power point of the energy generating system to be the maximum power point.

2. The control circuit as claimed in claim 1, wherein the ripple signal comprises a first waveform section and a second waveform section, the first ripple voltage exists in the first waveform section, and the second ripple voltage exists in the second waveform section, and when a voltage variation of the first waveform section varied along with time is greater than a voltage variation of the second waveform section varied along with time, the first ripple voltage is smaller than the second ripple voltage, wherein the voltage variations are varied with time.

3. The control circuit as claimed in claim 2, wherein when the voltage variation of the first waveform section varied along with time is smaller than the voltage variation of the second waveform section varied along with time, the first ripple voltage is greater than the second ripple voltage.

4. The control circuit as claimed in claim 1, wherein the sampling points are set by delaying a phase of a reference point while taking a peak point or a trough point of the reference signal as the reference point.

5. The control circuit as claimed in claim 1, wherein the sampling points comprise a first sampling point and a second sampling point, and the ripple signal comprises a waveform characteristic point, and the first sampling point and the second sampling point are set at two sides of the waveform characteristic point.

6. The control circuit as claimed in claim 5, wherein the waveform characteristic point is a peak point or a trough point of a signal waveform of the ripple signal.

7. The control circuit as claimed in claim 1, wherein the power point of the energy generating system corresponds to a first power voltage, the maximum power point of the energy generating system corresponds to a second power voltage, and the first control module takes the power point as an initial point to track the maximum power point of the energy generating system, wherein the first power voltage is greater than the second power voltage.

8. The control circuit as claimed in claim 1, wherein the first control module comprises:

a sampling and holding circuit, coupled to the power converter, configured to receive the ripple signal of the input voltage, and performing a sampling and holding operation to the ripple signal according to the sampling points, so as to obtain the ripple voltages;

a comparison circuit, coupled to the sampling and holding circuit, configured to compare the ripple voltages, and outputting a comparison result;

a counting circuit, coupled to the comparison circuit, and configured to generate a counting signal within a time period according to the comparison result; and

a digital-to-analog conversion circuit, coupled to the counting circuit, and configured to convert the counting signal into an analog signal to serve as the determination result, and outputting the determination result to the second control module.

9. The control circuit as claimed in claim 8, wherein the first control module further comprises:

a reference signal generating circuit, coupled to the power converter, and configured to generate the reference signal according to an output signal of the power converter.

10. The control circuit as claimed in claim 1, wherein the power converter is one of a boost power converter, a buck power converter and a flyback power converter or a combination of any two of the above power converters.

11. The control circuit as claimed in claim 1, wherein the input voltage of the power converter is generated by the energy generating system, and the energy generating system is one of a photovoltaic system, a hydroelectric system, a tidal power generation system, an ocean current power generation systems, a wind power generation system, a thermal power generation system, a pressure power generation system and a vibration energy power generation system.

12. The control circuit as claimed in claim 1, wherein the power converter is one of a DC-to-DC power converter and a DC-to-AC power converter.

13. A method for tracking a maximum power point, adapted to track the maximum power point of an energy generating system, the method for tracking the maximum power point comprising:

receiving a ripple signal of an input voltage of a power converter;

setting a plurality of sampling points for the ripple signal according to a reference signal, and determining phase information of the ripple signal; and

determining whether a power point of the energy generating system is the maximum power point according to a plurality of ripple voltages corresponding to the sampling points, wherein the ripple voltages comprise a first ripple voltage and a second ripple voltage, and the step of determining whether the power point of the energy generating system is the maximum power point comprises determining the power point of the energy generating system to be the maximum power point when the first ripple voltage is equal to the second ripple voltage.

14. The method for tracking the maximum power point as claimed in claim 13, further comprising:

taking a peak point or a trough point of the reference signal as a reference point and setting the sampling points by delaying the reference point by a phase.

15. The method for tracking the maximum power point as claimed in claim 13, wherein the power point of the energy generating system corresponds to a first power voltage, the maximum power point of the energy generating system corresponds to a second power voltage, and the method for tracking the maximum power point further comprises:

taking the power point as an initial point to track the maximum power point of the energy generating system, wherein the first power voltage is greater than the second power voltage.

16. The method for tracking the maximum power point as claimed in claim 13, wherein the sampling points comprise a first sampling point and a second sampling point, and the ripple signal comprises a waveform characteristic point, and the first sampling point and the second sampling point are set at two sides of the waveform characteristic point.

17. The method for tracking the maximum power point as claimed in claim 16, wherein the waveform characteristic point is a peak point or a trough point of a signal waveform of the ripple signal.

18. The method for tracking the maximum power point as claimed in claim 13, wherein the step of determining whether the power point of the energy generating system is the maximum power point comprises:

performing a sampling and holding operation to the ripple signal according to the sampling points, so as to obtain the ripple voltages;

comparing the ripple voltages, and outputting a comparison result;

generating a counting signal within a time period according to the comparison result; and

converting the counting signal into an analog signal to serve as the determination result.

19. The method for tracking the maximum power point as claimed in claim 13, further comprising:

generating the reference signal according to an output signal of the power converter.

20. The method for tracking the maximum power point as claimed in claim 13, wherein the power converter is one of a boost power converter, a buck power converter and a flyback power converter or a combination of any two of the above power converters.

21. The method for tracking the maximum power point as claimed in claim 13, wherein the input voltage of the power converter is generated by the energy generating system, and the energy generating system is one of a photovoltaic system, a hydroelectric system, a tidal power generation system, an ocean current power generation systems, a wind power generation system, a thermal power generation system, a pressure power generation system and a vibration energy power generation system.

22. The method for tracking the maximum power point as claimed in claim 13, wherein the power converter is one of a DC-to-DC power converter and a DC-to-AC power converter.