Switch mode power supply circuit with high voltage output, and electrostatic spray apparatus and agricultural plant protection apparatus using the same

A switch mode power supply circuit, comprising:

• N power conversion circuits, each power conversion circuit comprising a first terminal, a second terminal and a control terminal, wherein the Kth power conversion circuit comprises:
• a coil, comprising a first terminal and a second terminal, wherein the first terminal of the coil is coupled to the first terminal of the Kth power conversion circuit;
• a first unidirectional conduction element, comprising a first terminal and a second terminal, wherein the first terminal of the first unidirectional conduction element is coupled to the second terminal of the coil, and the second terminal of the first unidirectional conduction element is coupled to the second terminal of the Kth power conversion circuit, wherein the first unidirectional conduction element limits a current flowing from the first terminal of the first unidirectional conduction element to the second terminal of the first unidirectional conduction element;
• a second unidirectional conduction element, comprising a first terminal and a second terminal, wherein the first terminal of the second unidirectional conduction element is coupled to the second terminal of the coil, and the second terminal of the second unidirectional conduction element is coupled to the control terminal of the Kth power conversion circuit, wherein the second unidirectional conduction element limits a current flowing from the first terminal of the second unidirectional conduction element to the second terminal of the second unidirectional conduction element;
• a capacitor, comprising a first terminal and a second terminal, wherein the first terminal of the capacitor is coupled to the second terminal of the first unidirectional conduction element, and the second terminal of the capacitor is coupled to a second power voltage;
• a power converter, comprising:
• a transformer, comprising:
• a primary coil, comprising a first terminal and a second terminal, wherein the first terminal of the primary coil is coupled to the second terminal of Nth power conversion circuit;
• and
• a secondary coil;
• a switching device, comprising a first terminal, a second terminal and a control terminal, wherein the first terminal of the switching device is coupled to the second terminal of the primary coil and the control terminal of each power conversion circuit, wherein the second terminal of the switching device is coupled to the second power voltage;
• and
• a control circuit, coupled to the control terminal of the switching device for controlling the switching device,
• wherein the second terminal of Kth power conversion circuit is coupled to the first terminal of (K+1)th power conversion circuit,
• wherein N, K are natural numbers, and 0<K≤N.

An electrostatic spray apparatus, comprising:

• a nozzle;
• a polarization metal, comprising an opening, disposed behind the nozzle such that pesticide sprayed by nozzle can be passed through the polarization metal and be polarized by the polarization metal;
• a switch mode power supply circuit, comprising:
• a first coil, comprising a first terminal and a second terminal, wherein the first terminal of the first coil is coupled to a first power voltage;
• a first unidirectional conduction element, comprising a first terminal and a second terminal, wherein the first terminal of the first unidirectional conduction element is coupled to the second terminal of the first coil, wherein the first unidirectional conduction element limits current flowing from the first terminal of the first unidirectional conduction element to the second terminal of the first unidirectional conduction element;
• a second unidirectional conduction element, comprising a first terminal and a second terminal, wherein the first terminal of the second unidirectional conduction element is coupled to the second terminal of the first coil, wherein the second unidirectional conduction element limits current flowing from the first terminal of the second unidirectional conduction element to the second terminal of the second unidirectional conduction element;
• a first capacitor, comprising a first terminal and a second terminal, wherein the first terminal of the first capacitor is coupled to the second terminal of the first unidirectional conduction element, and the second terminal of the first capacitor is coupled to a second power voltage;
• a power converter, comprising:
• a transformer, comprising:
• a primary coil, comprising a first terminal and a second terminal, wherein the first terminal of the primary coil is coupled to the second terminal of the first unidirectional conduction element;
• and
• a secondary coil, coupled to the polarization metal;
• a switching device, comprising a first terminal, a second terminal and a control terminal, wherein the first terminal of the switching device is coupled to the second terminal of the primary coil and the second terminal of the second unidirectional conduction element, and the second terminal of the switching device is coupled to the second power voltage;
• and
• a control circuit, coupled to the control terminal of the switching device for controlling the switching device.

An agricultural plant protection apparatus, comprising:

• an aircraft, comprising:
• a battery;
• an electrostatic spray apparatus, comprising:
• a nozzle;
• a polarization metal, comprising an opening, disposed behind the nozzle, such that pesticide sprayed by nozzle can be pass through the polarization metal and be polarized by the polarization metal;
• a switch mode power supply circuit, comprising:
• a first coil, comprising a first terminal and a second terminal, wherein the first terminal of the first coil is coupled to the battery to receive a first power voltage;
• a first unidirectional conduction element, comprising a first terminal and a second terminal, wherein the first terminal of the first unidirectional conduction element is coupled to the second terminal of the first coil, wherein the first unidirectional conduction element limits current flowing from the first terminal of the first unidirectional conduction element to the second terminal of the first unidirectional conduction element;
• a second unidirectional conduction element, comprising a first terminal and a second terminal, wherein the first terminal of the second unidirectional conduction element is coupled to the second terminal of the first coil, wherein the second unidirectional conduction element limits current flowing from the first terminal of the second unidirectional conduction element to the second terminal of the second unidirectional conduction element;
• a first capacitor, comprising a first terminal and a second terminal, wherein the first terminal of the first capacitor is coupled to the second terminal of the first unidirectional conduction element, and the second terminal of the first capacitor is coupled to a second power voltage;
• a power converter, comprising:
• a transformer, comprising:
• a primary coil, comprising a first terminal and a second terminal, wherein the first terminal of the primary coil is coupled to the second terminal of the first unidirectional conduction element;
• and
• a secondary coil, coupled to the polarization metal;
• a switching device, comprising a first terminal, a second terminal and a control terminal, wherein the first terminal of the switching device is coupled to the second terminal of the primary coil and the second terminal of the second unidirectional conduction element, and the second terminal of the switching device is coupled to the second power voltage;
• and
• a control circuit, coupled to the control terminal of the switching device for controlling the switching device.