Energy storage system

1. An energy storage system configured to store power from a power generating unit, the energy storage system comprising:

a storage capacitor having a first end electrically coupled to one end of the power generating unit;

a secondary battery having a first terminal electrically coupled to a second end of the storage capacitor, and a second terminal electrically coupled to another end of the power generating unit;

a first converter configured to selectively couple the storage capacitor and the secondary battery to a load, the first converter comprising first and second switches coupled in series across the storage capacitor and the secondary battery; and

a transformer coupled to a contact point between the storage capacitor and the secondary battery and a contact point between the first and second switches.

2. The energy storage system as claimed in claim 1 , further comprising an inverter coupled to the first converter.

3. The energy storage system as claimed in claim 2 , further comprising a controller coupled to the first converter and the inverter, and configured to control an operation of the first converter.

4. The energy storage system as claimed in claim 2 , wherein the inverter comprises a bi-directional inverter.

5. The energy storage system as claimed in claim 1 , wherein the storage capacitor and the secondary battery are coupled to an output terminal of the power generating unit.

6. The energy storage system as claimed in claim 1 , further comprising a controller, wherein the controller is configured to apply a control signal to the first and second switches to form a path for supplying a power to the load through the storage capacitor or the secondary battery.

7. The energy storage system as claimed in claim 6 , wherein the controller is configured to drive the first and second switches complimentarily.

8. The energy storage system as claimed in claim 2 , wherein the transformer comprises:

a primary winding coupled to the contact point between the storage capacitor and the secondary battery and the contact point between the first and second switches; and

a secondary winding coupled to the inverter.

9. The energy storage system as claimed in claim 8 , further comprising a second converter coupled between the secondary winding of the transformer and the inverter, and for transducing an output power of the transformer into an Alternating Current (AC) power to be applied to the inverter or for transducing an output power of the inverter into a Direct Current (DC) power to be applied to the transformer.

10. The energy storage system as claimed in claim 9 , further comprising a link capacitor coupled between the second converter and the inverter in parallel, and for storing the power from the second converter or the inverter.

11. The energy storage system as claimed in claim 9 , wherein the second converter comprises four switches, and the four switches are transistors or diodes.

12. The energy storage system as claimed in claim 1 , wherein the first converter comprises a bi-directional converter.

13. The energy storage system as claimed in claim 1 , further comprising a maximum power point tracker coupled to an output terminal of the power generating unit, wherein the storage capacitor and the secondary battery are coupled in series across both ends of the maximum power point tracker.

14. The energy storage system as claimed in claim 7 , wherein the controller comprises an amplifier comprising an output,

wherein the output is directly connected to the second switch, and

wherein the output is connected to the first switch through an inverter.