Inverter

• US 20080055941A1
• Filed: 10/23/2007
• Published: 03/06/2008
• Est. Priority Date: 05/20/2005
• Status: Active Grant

• Current Assignee: SMA Solar Technology AG
• Original Assignee: SMA Technologie AG (SMA Solar Technology AG)
• Inventors: Muller, Burkhard, Falk, Andreas, Victor, Matthias
• Granted Patent: US 8,614,901 B2
• Time in Patent Office: Days
• US Class Current: 363/17
• 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 3/01 Resonant DC/DC converters
• CPC Class Codes: H02M 3/158 including plural semiconductor devices as final control devices for a single load
• CPC Class Codes: H02M 3/33571 Half-bridge at primary side of an isolation transformer
• CPC Class Codes: H02M 7/003 Constructional details, e.g. physical layout, assembly, wiring or busbar connections
• CPC Class Codes: H02M 7/53832 in a push-pull arrangement
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers
• CPC Class Codes: Y02P 80/10 Efficient use of energy, e.g. using compressed air or pressurized fluid as energy carrier

Abstract

An inverter (1) with galvanic separation including a resonant converter (2) and an upstream mounted boost chopper (3) is intended to provide galvanic separation in the context of a variable input and output voltage as it exists in photovoltaic systems, with the efficiency being intended to be optimized over the entire input voltage range. This is achieved in that a boost chopper (3) or a buck chopper (4) is mounted upstream of the resonant converter (2).

Claims

1. An inverter with galvanic separation and with a DC-input, characterized in

that, at the DC-input, the inverter comprises a resonant converter (2) having an upstream mounted boost chopper (3) or buck chopper.

2. The inverter as set forth in claim 1, characterized in

that one boost chopper (3) only is mounted upstream of the resonant converter.

3. The inverter as set forth in claim 1, characterized in

that the inverter is configured to be a single-phase inverter.

4. The inverter as set forth in claim 1, characterized in

that the resonant converter comprises a power electronic half-bridge circuit (S1, S2), a series resonant capacitance (C₁) and a high frequency transformer (HFT).

5. The inverter as set forth in claim 4, characterized in

that the repetition rate of the half-bridge circuit is lower than the resonance frequency which is obtained from the leakage inductance of the transformer and the series resonant capacitance (C₁).

6. The inverter as set forth in claim 1, characterized by

synchronous activation of the boost chopper (3) and of the resonant converter (2).

7. The inverter as set forth in claim 1, characterized in

that the boost chopper (3) is operated in the interval mode.

8. The inverter as set forth in claim 1, characterized in

that the boost chopper (3) is operated at a variable repetition rate.

9. The inverter as set forth in claim 1, characterized in

that the transformer is configured to be a planar transformer (10).

10. The inverter as set forth in claim 9, characterized in

that leakage inductance of the planar transformer is increased by introducing a reactor core with an air gap that is wound either with the primary winding only or with the secondary winding only.

11. The inverter as set forth in claim 1, characterized in

that it includes a cast housing (16) comprising contact surfaces for heat coupling that are stepped in such a manner that the planar transformer and two overlapping printed circuit boards can be coupled.

12. The inverter as set forth in claim 9, characterized in

that the planar transformer is provided with two overlapping printed circuit boards (14, 15).

13. The inverter as set forth claim 1, characterized by

an activation behavior that only activates the boost chopper when the intermediate circuit voltage at the capacitor C_mains drops below the voltage needed for mains electricity supply in the actual operating point.

14. The inverter as set forth in claim 1, characterized in

that the resonant capacitances C5 and C6 are disposed in the DC-circuit.

15. The inverter as set forth in claim 14, characterized in

that a large DC filter capacitor (C12) is disposed parallel to C5 and C6.

16. The inverter as set forth in claim 1, characterized in

that power from a PV generator is fed into the mains supply.