Power supply circuits

1. A photovoltaic power conditioning circuit for providing power to an alternating current (AC) mains power supply line, the photovoltaic power conditioning circuit comprising:

a DC-to-AC converter configured to convert DC power from a DC input to AC power for outputting onto the AC mains power supply line, the AC mains power supply line comprising a voltage with a first frequency and the AC power output comprising a current with a second frequency; and

an electronic controller configured to determine the first and second frequencies and to control the DC-to-AC converter responsive to a difference between the first and second frequencies.

2. The photovoltaic power conditioning circuit of claim 1 , wherein the DC input receives the DC power from a photovoltaic device.

3. The photovoltaic power conditioning circuit of claim 1 , wherein the electronic controller is further configured to:

control the DC-to-AC converter to progressively change the second frequency,

monitor the first and second frequencies to determine whether the first frequency substantially follows the second frequency during the progressive change, and

responsive to the determination, inhibit the AC power output to the AC mains power supply line.

4. The photovoltaic power conditioning circuit of claim 1 further comprising:

a plurality of power semiconductor devices, each power semiconductor device comprising a device conducing power from the DC input to the AC mains power supply line; and

a plurality of drivers for the driving power semiconductor devices, wherein the power devices and the drivers are integrated on a common semiconductor substrate.

5. The photovoltaic power conditioning circuit of claim 4 , wherein the power devices comprise lateral devices and employ silicon-on-insulator (SOI) technology.

6. The photovoltaic power conditioning circuit of claim 1 further comprising a DC-to-DC converter having an input coupled to the DC input and having an output coupled to an input of the DC-to-AC converter.

7. The photovoltaic power conditioning circuit of claim 1 further comprising a rechargeable battery interface.

8. The photovoltaic power conditioning circuit of claim 1 , wherein the electronic controller comprises a processor coupled to non-volatile program memory storing processor control code to control the processor to measure the voltage and the current and to output a control signal to control the DC-to-AC converter.

9. The photovoltaic power conditioning circuit of claim 1 , wherein the DC-to-AC converter comprises at least one full bridge.

10. The photovoltaic power conditioning circuit of claim 1 , wherein the DC-to-AC converter comprises:

a first AC stage having a plurality of metal-oxide-semiconductor field-effect transistors (MOSFETs); and

a second AC stage comprising a plurality of insulated gate bipolar transistors (IGBTs), the second AC stage operating at a higher voltage than the first AC stage.

11. A photovoltaic power conditioning circuit for providing power from a photovoltaic device to an alternating current (AC) mains power supply line, the photovoltaic power conditioning circuit comprising:

a DC input to receive DC power from the photovoltaic device;

an AC output configured for direct connection to the AC mains power supply line;

a DC-to-AC converter coupled to the DC input and to the AC output configured to convert DC power from the photovoltaic device to AC power for output onto the AC mains power supply line;

an electronic controller directly coupled to the AC mains power supply line configured to measure a voltage of the AC mains power supply line and a current from the DC-to-AC converter and to control the DC-to-AC converter responsive to the measuring;

a maximum power point tracking (MPPT) circuit coupled to the DC input; and

a rechargeable battery interface with an input coupled to an output of the MPPT circuit.

12. The photovoltaic power conditioning circuit of claim 11 , wherein the DC-to-AC converter comprises:

a first AC stage having a plurality of metal-oxide-semiconductor field-effect transistors (MOSFETs); and

a second AC stage comprising a plurality of insulated gate bipolar transistors (IGBTs), the second AC stage operating at a higher voltage than the first AC stage.

13. The photovoltaic power conditioning circuit of claim 11 , wherein the MPPT circuit receives DC power from the photovoltaic device and transfers the received DC power to both the rechargeable battery interface and the DC-to-AC converter.

14. A method of conditioning power from a photovoltaic device for provision to an alternating current (AC) mains power supply line, the method comprising:

reading data for a voltage on the AC mains power supply line and a current into the AC mains power supply line at an electronic controller;

determining a first frequency for the voltage and a second frequency for the current using the electronic controller; and

conditioning the power using the electronic controller responsive to a difference between the first and second frequencies.

15. The method as claimed in claim 14 , wherein conditioning the power comprises converting DC power from the photovoltaic device to AC power for the AC supply line, wherein the method further comprises:

controlling the converting to change the second frequency;

monitoring the first and second frequencies; and

ceasing to supply power to the AC supply line responsive to the difference between the first and second frequencies being less than a threshold difference.

16. The method of claim 14 , wherein the steps of reading, determining, and conditioning are performed by a photovoltaic power supply system.

17. The method of claim 14 , wherein conditioning the power comprises controlling the second frequency.

18. A power conditioning integrated circuit for providing power to an alternating current (AC) mains power supply line from a photovoltaic device, the power conditioning circuit comprising:

a first AC stage configured to convert direct current (DC) power from the photovoltaic device to a first AC power, the first AC stage comprising a plurality of metal-oxide-semiconductor field-effect transistors (MOSFETs); and

a second AC stage that operates at a higher voltage than the first AC stage configured to convert the first AC power to a second AC power, the second AC stage comprising a plurality of insulated gate bipolar transistors (IGBTs), wherein a portion of the first AC stage is electrically isolated from the second AC stage;

wherein the power conditioning integrated circuit is a silicon-on-insulator integrated circuit comprising a buried oxide layer, and wherein the first AC stage is electrically isolated from the second AC stage with a dielectric filled trench on the power conditioning integrated circuit extending down to contact the buried oxide layer.

19. The power conditioning circuit of claim 18 , wherein both first and second stages comprise a full bridge.