Multilevel voltage driving device

1. A multilevel voltage driving device, comprising:

a level converter, which is provided with an AC signal input terminal for inputting an AC signal, a high level output terminal for outputting a high level, and an intermediate level output terminal for outputting an intermediate level; and

a switch selector, which is connected with the high level output terminal and the intermediate level output terminal, and which is provided with a control signal input terminal, for inputting a control signal to alternately select the high level and the intermediate level, and an output terminal for outputting the selected level;

wherein the level converter further comprises:

a reference level input terminal for inputting a reference level for the high level and the intermediate level;

two branches in parallel, two terminals of the branches being connected with the AC signal input terminal and ground, respectively, wherein one of the branches sequentially comprises a third capacitor, a first diode, and a first capacitor connected in series, and another one of the branches sequentially comprises a fourth capacitor, a second diode, and a second capacitor connected in series; and wherein one terminal of the first capacitor is connected with the ground and another terminal of the first capacitor is connected with a negative electrode of the first diode, one terminal of the second capacitor is connected with the ground and another terminal of the second capacitor is connected with a negative electrode of the second diode, the negative electrode of the first diode is connected with the intermediate level output terminal, and the negative electrode of the second diode is connected with the high level output terminal;

a third diode, wherein a positive electrode of the third diode is connected with the intermediate level output terminal, and a negative electrode of the third diode is connected with a positive electrode of the second diode; and

a fourth diode, wherein a negative electrode of the fourth diode is connected with a positive electrode of the first diode, and a positive electrode of the fourth diode is connected with the reference level input terminal.

2. The multilevel voltage driving device according to claim 1 , wherein the switch selector comprises:

a first switch and a second switch, wherein output terminals of the first switch and second switch are connected with each other, an input terminal of the first switch is connected with the high level output terminal, an input terminal of the second switch is connected with the intermediate level output level; and

a third switch, of which a control terminal is connected with the control signal input terminal, an input terminal is connected with the ground, and an output terminal is connected with control terminals of the first switch and second switch.

3. The multilevel voltage driving device according to claim 2 , wherein a first resistor is connected between the input terminal and the control terminal of the first switch.

4. The multilevel voltage driving device according to claim 2 , wherein the output terminal of the third switch is connected with the control terminal of the first switch via a third resistor and a second resistor connected in series.

5. A multilevel voltage driving system comprising the multilevel voltage driving device according to claim 1 and further comprising an AC signal source which is connected with the AC signal input terminal of the multilevel voltage driving device.

6. The multilevel voltage driving system according to claim 5 , further comprising a reference level signal source which is connected with the reference level input terminal of the multilevel voltage driving device.

7. The multilevel voltage driving system according to claim 5 , further comprising a control signal source which is connected with the control signal input terminal of the multilevel voltage driving device.