Voltage conversion device and voltage conversion method thereof

A voltage conversion method used with a voltage conversion device comprising a filter circuit, a first conversion module, and a second conversion module, wherein the first conversion module comprises a plurality of first switch units and the second conversion module comprises a plurality of second switch units, wherein the voltage conversion method comprises steps of:

• the first conversion module and the second conversion module receiving a DC voltage from a battery module;
• the first conversion module and the second conversion module generating a modified sine wave between a first conversion terminal and a second conversion terminal;
• and
• the filter circuit filtering the modified sine wave to generate an AC voltage, wherein:
• the modified sine wave has a voltage equal to a positive DC voltage value when the first switch units and the second switch units enter a first conversion state;
• the modified sine wave has a voltage equal to half the positive DC voltage value when the first switch units and the second switch units enter a second conversion state or a third conversion state;
• the modified sine wave has a voltage equal to a ground voltage when the first switch units and the second switch units enter a fourth conversion state or a fifth conversion state;
• the modified sine wave has a voltage equal to half a negative DC voltage value when the first switch units and the second switch units enter a sixth conversion state or a seventh conversion state;
• and
• the modified sine wave has a voltage equal to the negative DC voltage value when the first switch units and the second switch units enter an eighth conversion state, wherein:
• the first switch units and the second switch units being switched on and configured for receiving a first PWM signal in the first conversion state are switched off in the eighth conversion state;
• the first switch units and the second switch units being switched on and configured for receiving a second PWM signal in the second conversion state are switched off in the seventh conversion state;
• the first switch units and the second switch units being switched on and configured for receiving a third PWM signal in the third conversion state are switched off in the sixth conversion state;
• the first switch units and the second switch units being switched on and configured for receiving a fourth PWM signal in the fourth conversion state are switched off in the fifth conversion state;
• the first switch units and the second switch units being switched on and configured for receiving a fifth PWM signal in the fifth conversion state are switched off in the fourth conversion state;
• the first switch units and the second switch units being switched on and configured for receiving a sixth PWM signal in the sixth conversion state are switched off in the third conversion state;
• the first switch units and the second switch units being switched on and configured for receiving a seventh PWM signal in the seventh conversion state are switched off in the second conversion state;
• and
• the first switch units and the second switch units being switched on and configured for receiving an eighth PWM signal in the eighth conversion state are switched off in the first conversion state.

A voltage conversion method used with a voltage conversion device comprising a first inductor, a second inductor, a first conversion module and a second conversion module, wherein the voltage conversion method comprises steps of:

• receiving an AC voltage between a first AC terminal and a second AC terminal, wherein the first inductor is electrically connected between the first conversion module and the first AC terminal, and the second inductor is electrically connected between the second conversion module and the second AC terminal;
• a first lower conversion circuit, a first lower inner circuit and a first lower middle circuit of the first conversion module and a second upper middle circuit, a second upper inner circuit, and a second upper conversion circuit of the second conversion module receiving a first PWM signal when the AC voltage rises from a ground voltage to a positive DC voltage value, wherein a first current from the first AC terminal flows to the second AC terminal through the first inductor, the first conversion module, a third DC voltage terminal, the second conversion module and the second inductor sequentially to generate a DC voltage between a first DC voltage terminal and a second DC voltage terminal;
• a first upper conversion circuit, a first upper inner circuit and a first upper DC circuit of the first conversion module and a second lower DC circuit, a second lower inner circuit and a second lower conversion circuit of the second conversion module receiving a second PWM signal when the AC voltage is decreasing from the positive DC voltage value to the ground voltage, wherein a second current from the first AC terminal flows to the second AC terminal through the first inductor, the first conversion module, the first DC voltage terminal, a battery module, the second DC voltage terminal, the second conversion module, and the second inductor sequentially to generate the DC voltage;
• the second lower conversion circuit, the second lower inner circuit and a second lower middle circuit of the second conversion module and a first upper middle circuit, the first upper inner circuit, and the first upper conversion circuit of the first conversion module receiving a third PWM signal when the AC voltage is decreasing from the ground voltage to a negative DC voltage value, wherein a third current from the second AC terminal flows to the first AC terminal through the second inductor, the second conversion module, the third DC voltage terminal, the first conversion module, and the first inductor sequentially to generate the DC voltage;
• and
• the second upper conversion circuit, the second upper inner circuit and a second upper DC circuit of the second conversion module and a first lower DC circuit, the first lower inner circuit, and the first lower conversion circuit of the first conversion module receiving a fourth PWM signal when the AC voltage rises from the negative DC voltage value to the ground voltage, wherein a fourth current from the second AC terminal flows to the first AC terminal through the second inductor, the second conversion module, the first DC voltage terminal, the battery module, the second DC voltage terminal, the first conversion module, and the first inductor sequentially to generate the DC voltage.