Inverter device and controlling method thereof

1. An inverter device electrically connected to a direct current source, comprising:

a first stage circuit electrically connected to the direct current source and comprising a first switch module and a charge-discharge module, wherein the first switch module is electrically connected to the charge-discharge module;

a second stage circuit electrically connected to the first stage circuit and an AC output terminal and comprising a second switch module and a filter module, wherein the second switch module is electrically connected to the filter module; and

a control module electrically connected to the first switch module and the second switch module, and outputting a first control signal for controlling the first switch module to turn on/off and a second control signal for controlling the second switch module to turn on/off;

wherein the control module obtains an input current from the first stage circuit, the control module determines a predetermined current value with a varied capacitor voltage of a capacitor included in the charge-discharge module and adjusts the input current to be approaching to the predetermined current value, and the control module obtains an output power from the AC output terminal and adjusts the duty cycle of the first control signal according to the output power and a predetermined output power.

2. The inverter device according to claim 1 , wherein the control module increases the duty cycle of the first control signal when the output power is greater than the predetermined output power, and decreases the duty cycle of the first control signal when the output power is smaller than the predetermined output power.

3. The inverter device according to claim 2 , wherein the control module controls the first switch module to operate in a high frequency switching mode and a zero voltage switching mode and controls the second switch module to operate in the high frequency switching mode and the zero voltage switching mode, and a Schottky diode or a parasitic capacitor is connected in parallel between the drain and source electrodes of each switch of the second switch module.

4. The inverter device according to claim 1 , wherein the charge-discharge module is an inductor and a capacitor, the inductor is electrically connected to the first switch module and the capacitor, and the capacitor is electrically connected to the inductor and a grounding terminal.

5. The inverter device according to claim 4 , wherein the control module controls the first switch module to operate in a high frequency switching mode and a zero voltage switching mode and controls the second switch module to operate in the high frequency switching mode and the zero voltage switching mode, and a Schottky diode or a parasitic capacitor is connected in parallel between the drain and source electrodes of each switch of the second switch module.

6. The inverter device according to claim 1 , wherein the first stage circuit is a DC-DC transformation circuit, the second stage circuit is a DC-AC transformation circuit, the DC-DC transformation circuit is a buck circuit, a boost circuit or a buck-boost circuit, and the DC-AC transformation circuit is a bridge inverter circuit.

7. The inverter device according to claim 6 , wherein the control module controls the first switch module to operate in a high frequency switching mode and a zero voltage switching mode and controls the second switch module to operate in the high frequency switching mode and the zero voltage switching mode, and a Schottky diode or a parasitic capacitor is connected in parallel between the drain and source electrodes of each switch of the second switch module.

8. The inverter device according to claim 1 , wherein the first stage circuit blocks the ripple current which flows from the second stage circuit to the first stage circuit.

9. The inverter device according to claim 8 , wherein the control module controls the first switch module to operate in a high frequency switching mode and a zero voltage switching mode and controls the second switch module to operate in the high frequency switching mode and the zero voltage switching mode, and a Schottky diode or a parasitic capacitor is connected in parallel between the drain and source electrodes of each switch of the second switch module.

10. The inverter device according to claim 1 , wherein the control module controls the first switch module to operate in a high frequency switching mode and a zero voltage switching mode and controls the second switch module to operate in the high frequency switching mode and the zero voltage switching mode, and a Schottky diode or a parasitic capacitor is connected in parallel between the drain and source electrodes of each switch of the second switch module.

11. A method of controlling an inverter device, wherein the inverter device comprises: a first stage circuit, a second stage circuit and a control module; the first stage circuit electrically connected to a DC power and the second stage circuit, the second stage circuit electrically connected to the first stage circuit and an AC output terminal; the control module electrically connected to the first stage circuit and the second stage circuit; wherein the first stage circuit comprises a first switch module and a charge-discharge module, the first switch module is electrically connected to the charge-discharge module, the second stage circuit comprises a second switch module and a filter module, the second switch module is electrically connected to the filter module, wherein the method comprises the following steps:

the control module obtaining an input current which flows into the first stage circuit, the control module determining a predetermined current value with a varied capacitor voltage of a capacitor included in the charge-discharge module and adjusting the input current to be approaching to the predetermined current value, and

the control module obtaining an output power from the AC output terminal, and adjusting the duty cycle of the first control signal according to a predetermined output power and the output power.

12. The method according to claim 11 , wherein in the step of the control module adjusting the duty cycle of the first control signal according to the predetermined output power and the output power further comprises the step of:

the control module increasing the duty cycle of the first control signal when the output power is greater than the predetermined output power; and

the control module decreasing the duty cycle of the first control signal when the output power is smaller than the predetermined output power.