Control method for DC to AC converter

• US 9,467,066 B1
• Filed: 12/08/2015
• Issued: 10/11/2016
• Est. Priority Date: 10/07/2015
• Status: Active Grant

• Current Assignee: Industrial Technology Research Institute
• Original Assignee: Industrial Technology Research Institute
• Inventors: Chen, Po-Li, Yu, Ming-Hung
• Primary Examiner(s): Berhane, Adolf
• Assistant Examiner(s): NASH, GARY A
• Application Number:
  US14/962,773
• Time in Patent Office: 308 Days
• Field of Search: 363/37, 363 78- 80, 363/97, 363/98, 363/131, 363/132, 363/137, 363/138
• 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: H02J 2300/24 of photovoltaic origin
• CPC Class Codes: H02J 2300/26 involving maximum power point tracking control for photovoltaic sources maximum power point systems in particular G05F1/67
• CPC Class Codes: H02J 3/381 Dispersed generators
• CPC Class Codes: H02M 7/537 using semiconductor devices only, e.g. single switched pulse inverters
• CPC Class Codes: H02M 7/53871 with automatic control of output voltage or current
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers

Abstract

A control method for a DC to AC converter, selectively operating in a continuous conduction mode and a discontinuous conduction mode is disclosed. In the discontinuous conduction mode, the DC to AC converter outputs a first output signal having a first work frequency according to a power value of an input signal. The first work frequency relates to a plurality of first cycles. A first transition period and a first standby period in each first cycle have a first time ratio therebetween. Determine a power value of the first output signal produced during the first transition period. When the power value of the first output signal increases, the first work frequency is increased. When the power value of the first output signal decreases, the first work frequency is decreased.

Claims

1. A control method applied to a DC to AC converter capable of selectively operating in a continuous conduction mode or in a discontinuous conduction mode, in which the control method comprises:

outputting a first output signal in a first work frequency according to a power value of an input signal, wherein the first work frequency is associated with a plurality of first cycles, and a first transition period and a first standby period in each of the plurality of first cycles have a first time ratio therebetween;

detecting a power value of the first output signal during the first transition period;

increasing the first work frequency when the power value of the first output signal is increasing; and

reducing the first work frequency when the power value of the first output signal is decreasing.

2. The control method according to claim 1, wherein each of the plurality of first cycles comprises a plurality of time internals, and the first time ratio between the first transition period and the first standby period is a percentage of the time internals that is occupied.

3. The control method according to claim 1, further comprising:

determining a range of the power value of the input signal; and

determining the first time ratio between the first transition period and the first standby period according to the range of the power value of the input signal.

4. The control method according to claim 1, further comprising:

converting the input signal into the first output signal during the first transition period, wherein a conversion rate of the first output signal to the input signal is not smaller than a preset conversion rate.

5. The control method according to claim 4, wherein outputting the first output signal in the first work frequency according to the power value of the input signal comprises determining the first time ratio between the first transition period and the first standby period according to a ratio between the power value of the input signal and a preset power value.

6. The control method according to claim 5, wherein when the first time ratio between the first transition period and the first standby period is equal to a first preset ratio during the first transition period and the conversion rate of the first output signal to the input signal is smaller than the preset conversion rate, the DC to AC converter stops outputting the first output signal.

7. The control method according to claim 5, wherein when the first output signal is being outputted in the first work frequency and the first transition period is proceeding, the control method further comprises:

outputting a second output signal in a second work frequency according to the power value of the input signal,

wherein the second output signal and the first output signal have a difference in phase therebetween, the second work frequency is associated with a plurality of second cycles, and a second transition period and a second standby period in each of the plurality of second cycles have a second time ratio therebetween.

8. The control method according to claim 7, further comprising:

detecting a sum of the power value of the first output signal and a power value of the second output signal;

increasing the second work frequency when the sum of the power values of the first output signal and the second output signal is increasing; and

decreasing the second work frequency when the sum of the power values of the first output signal and the second output signal is decreasing.

9. The control method according to claim 7, wherein outputting the second output signal in the second work frequency according to the power value of the input signal comprises determining the second time ratio between the second transition period and the second standby period according to the power value of the input signal, the power value of the first output signal and the preset power value.

10. The control method according to claim 9, wherein when the second time ratio between the second transition period and the second standby period is equal to a second preset ratio and a conversion rate of the second output signal to the input signal is smaller than the preset conversion rate during the second transition period, the first output signal is selectively outputted instead of the second output signal.