Power converting apparatus and photovoltaic module

• US 9,281,759 B2
• Filed: 01/25/2013
• Issued: 03/08/2016
• Est. Priority Date: 01/27/2012
• Status: Active Grant

• Current Assignee: Trina Solar Limited
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Lee, Kiok, Kim, Myonghwan, Hwang, Eonjoo
• Primary Examiner(s): Tran, Thienvu
• Assistant Examiner(s): Sun, Pinping
• Application Number:
  US13/749,870
• Publication Number:
  US 20130193775A1
• Time in Patent Office: 1,138 Days
• US Class Current: 1/1
• 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: H02J 3/40 Synchronising a generator for connection to a network or to another generator
• CPC Class Codes: H02M 1/007 Plural converter units in cascade push-pull DC/DC converters with pre-regulator H02M3/3374; DC-AC converters following a DC-DC stage including a high frequency transformer H02M7/4807; DC-AC converters following a DC-DC conversion stage generating periodically varying voltages H02M7/4826
• CPC Class Codes: H02M 3/156 with automatic control of output voltage or current, e.g. switching regulators
• CPC Class Codes: H02M 3/1582 Buck-boost converters H02M3/1584 takes precedence
• CPC Class Codes: H02M 3/1584 with a plurality of power processing stages connected in parallel
• CPC Class Codes: H02M 3/1586 switched with a phase shift, i.e. interleaved
• CPC Class Codes: H02M 3/3353 having at least two simultaneously operating switches on the input side, e.g. "double forward" or "double (switched) flyback" converter
• 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 power converting apparatus and a photovoltaic module are discussed. The power converting apparatus includes a converter including a tapped inductor and a first switch, the converter converting a level of an input direct current (DC) voltage and outputting the level-converted DC voltage, and an inverter including a plurality of switches, the inverter converting the level-converted DC voltage into an alternating current (AC) voltage. The inverter operates separately in a first switching mode where the inverter performs a switching operation at a first frequency for a first period of the converted AC voltage and a second switching mode where the inverter performs a switching operation at a second frequency for a second period of the converted AC voltage, the second frequency being lower than the first frequency.

Claims

1. A power converting apparatus comprising:

a converter including a tapped inductor and a first switch, the converter configured to convert a level of an input direct current (DC) voltage and output the level-converted DC voltage; and

an inverter including a plurality of switches, the inverter configured to convert the level-converted DC voltage into an alternating current (AC) voltage,

wherein the inverter operates separately in a first switching mode where the inverter performs a switching operation at a first frequency during a first period of the converted AC voltage and a second switching mode where the inverter performs a switching operation at a second frequency during a second period of the converted AC voltage, the second frequency being lower than the first frequency,

wherein the first period corresponds to a constant-voltage period of the input DC voltage converted by the converter, and

wherein the first switch of the converter performs a switching operation at a switching frequency higher than the first frequency in the first period of the first switching mode of the inverter.

2. The power converting apparatus according to claim 1, wherein the converter converts the level of the input DC voltage to output a level-converted pseudo DC voltage as the level converted DC voltage.

3. The power converting apparatus according to claim 1, further comprising a filter configured to low pass filter the AC voltage output from the inverter.

4. The power converting apparatus according to claim 1, wherein the converter comprises a plurality of converters connected in parallel, each of the plurality of converters comprising a tapped inductor and a switch.

5. The power converting apparatus according to claim 4, wherein at least a part of the plurality of converters operates corresponding to a power requirement for the converted AC voltage.

6. The power converting apparatus according to claim 1, further comprising a controller configured to control switching operations of the first switch of the converter and the plurality of switches of the inverter.

7. The power converting apparatus according to claim 1, wherein the inverter outputs an AC voltage waveform falling to a ground voltage in the first period of the first switching mode.

8. A photovoltaic module comprising:

a solar cell module including a plurality of solar cells; and

a power converting unit configured to convert direct current (DC) power supplied from the solar cell module into alternating current (AC) power,

wherein the power converting unit includes;

a converter including a tapped inductor and a first switch, the converter configured to convert a level of an input DC voltage and output the level-converted DC voltage; and

an inverter including a plurality of switches, the inverter configured to convert the level-converted DC voltage into an AC voltage,

wherein the inverter operates separately in a first switching mode where the inverter performs a switching operation at a first frequency during a first period of the converted AC voltage and a second switching mode where the inverter performs a switching operation at a second frequency during a second period of the converted AC voltage, the second frequency being lower than the first frequency,

wherein the first period corresponds to a constant-voltage period of the input DC voltage converted by the converter, and

wherein the first switch of the converter performs a switching operation at a switching frequency higher than the first frequency in the first period of the first switching mode of the inverter.

9. The photovoltaic module according to claim 8, wherein the power converting unit further comprises a bypass diode to bypass a solar cell in which a backward voltage is generated, among the plurality of solar cells.

10. The photovoltaic module according to claim 8, wherein the converter and the inverter in the power converting unit are installed in a junction box, and

wherein the junction box is attached to the solar cell module integrally therewith.

11. The photovoltaic module according to claim 8, wherein the converter in the power converting unit is installed in a junction box, and

wherein the junction box is attached to the solar cell module integrally therewith.

12. The photovoltaic module according to claim 8, wherein the inverter outputs an AC voltage waveform falling to a ground voltage in the first period of the first switching mode.

13. A power converting apparatus comprising:

a switching unit including a switch, the switching unit configured to switch an input direct current (DC) voltage to selectively output the DC voltage;

a converter including a tapped inductor and a switch, the converter configured to convert a level of the DC voltage from the switching unit and output the level-converted DC voltage; and

an inverter including a plurality of switches, the inverter configured to convert the level-converted DC voltage into an alternating current (AC) voltage,

wherein the converter operates in a first power conversion mode for a turn-off period of the switch of the switching unit and in a second power conversion mode for a turn-on period of the switch of the switching unit,

wherein the switch of the converter performs a switching operation at a first frequency in the first power conversion mode and performs a switching operation at a second frequency in the second power conversion mode,

wherein the second frequency is lower than the first frequency, and

wherein a period of the first power conversion mode corresponds to a constant-voltage period of the input DC voltage converted by the converter.

14. The power converting apparatus according to claim 13, wherein the first power conversion mode is a buck mode, and the second power conversion mode is a boost mode.

15. The power converting apparatus according to claim 13, wherein the inverter performs a switching operation at a fixed switching frequency in the first power conversion mode and the second power conversion mode.

16. The power converting apparatus according to claim 13, wherein the converter includes a plurality of converters connected in parallel, each of the plurality of converters including a tapped inductor and a switch.

17. The power converting apparatus according to claim 13, further comprising a controller configured to control switching operations of the switch of the switching unit, the switch of the converter and the plurality of switches of the inverter.

18. A photovoltaic module comprising:

a solar cell module including a plurality of solar cells; and

a power converting unit configured to convert direct current (DC) power supplied from the solar cell module into alternating current (AC) power,

wherein the power converting unit includes;

a switching unit including a switch, the switching unit configured to switch an input DC voltage to selectively output the DC voltage;

a converter including a tapped inductor and a switch, the converter configured to convert a level of the DC voltage from the switching unit and output the level-converted DC voltage; and

an inverter including a plurality of switches, the inverter configured to convert the level-converted DC voltage into an AC voltage,

wherein the converter operates in a first power conversion mode for a turn-off period of the switch of the switching unit and in a second power conversion mode for a turn-on period of the switch of the switching unit,

wherein the switch of the converter performs a switching operation at a first frequency in the first power conversion mode and performs a switching operation at a second frequency in the second power conversion mode,

wherein the second frequency is lower than the first frequency, and

wherein a period of the first power conversion mode corresponds to a constant-voltage period of the input DC voltage converted by the converter.

19. The photovoltaic module according to claim 18, wherein the converter, switching unit and inverter in the power converting unit are installed in a junction box, and

wherein the junction box is attached to the solar cell module integrally therewith.

20. The photovoltaic module according to claim 18, wherein the converter and the switching unit in the power converting unit is installed in a junction box, and

wherein the junction box is attached to the solar cell module integrally therewith.

21. The photovoltaic module according to claim 18, wherein the inverter outputs an AC voltage waveform falling to a ground voltage in the first period of the first switching mode.