Multi-Stage High-Voltage Power Supply for Lightweight Electrostatic Spraying
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Solution Overview
Problem
Existing high-voltage electrostatic spray apparatuses for agricultural plant protection are costly and heavy, making them unsuitable for unmanned agricultural applications due to the large transformer and high-voltage circuit requirements.
Innovation Solution
A switch mode power supply circuit with a reduced transformer turns ratio, utilizing multiple power conversion circuits in series controlled by a switching device, which miniaturizes the transformer and simplifies control, enabling the use in unmanned agricultural plant protection apparatuses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional high-voltage electrostatic spray apparatus is used, then the pesticide adhesion and spraying effect are improved, but the device weight and size increase due to large transformer and high-voltage circuit components
Solution Approach 1:
The power supply circuit is divided into multiple stages (first power conversion circuit, second power conversion circuit, and flyback power converter), with each stage performing a specific voltage conversion function. This segmentation allows the use of smaller transformers at each stage rather than one large transformer, reducing overall weight while achieving the required high voltage output for electrostatic spraying.
Solution Approach 2:
Multiple power conversion circuits are combined in series to achieve the cumulative voltage multiplication effect. The first and second power conversion circuits boost the input voltage, and the flyback power converter provides additional voltage transformation and isolation, collectively delivering the high voltage needed for electrostatic spray generation without requiring a single large transformer.
2Reliability
If a traditional high-voltage electrostatic spray apparatus is used, then the pesticide adhesion and spraying effect are improved, but the device complexity and cost increase due to high turns ratio transformer requirements
Solution Approach 1:
The voltage transformation is segmented across multiple circuits with moderate turns ratios rather than one transformer with an extreme turns ratio. Each transformer in the multi-stage configuration has a more manageable turns ratio, simplifying design and reducing complexity while achieving the same overall voltage multiplication.
Solution Approach 2:
The invention changes the operating parameters of the power conversion system by using multiple stages with specific duty cycles and switching frequencies. The first and second power conversion circuits operate with duty cycles between 0.2-0.8, and the flyback converter uses a turns ratio between 1:5 to 1:10, optimizing performance while simplifying individual component specifications.
3Weight of moving object
If a multi-stage power conversion circuit is used, then the transformer turns ratio is reduced and weight is decreased, but the control complexity may increase
Solution Approach 1:
The control circuit incorporates feedback mechanisms to monitor and regulate the output voltage of the multi-stage power conversion system. This feedback control allows the system to automatically adjust switching parameters and maintain stable high-voltage output, simplifying the overall control task despite the multi-stage architecture by providing self-regulation.
Solution Approach 2:
The power conversion circuits are designed to operate with inherent stability characteristics, where the circuit topology and component values are selected to provide natural regulation. The flyback power converter, in particular, provides galvanic isolation and voltage regulation through its inherent operating principles, reducing the burden on external control circuitry.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution allows for a lightweight, compact, and efficient high-voltage output suitable for unmanned agricultural plant protection systems, improving the adhesion and distribution of pesticides on plants while reducing the size and weight of the transformer.
Implementation Method 1
The first unidirectional conduction element includes 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 the current flowing from the first terminal of the first unidirectional conduction element to the second terminal of the first unidirectional conduction element
Implementation Method 2
The second unidirectional conduction element includes 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 the current flowing from the first terminal of the second unidirectional conduction element to the second terminal of the second unidirectional conduction element
Implementation Method 3
The power converter includes a transformer and a switching device. The transformer includes a primary coil and a secondary coil
Implementation Method 4
The switching device includes 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
Data Source
AI summary
A switch mode power supply circuit with high voltage output, an electrostatic spray apparatus and agricultural plant protection apparatus using the same are provided. The switch mode power supply circuit is electrically connected in series with at least a pre-stage power converter and a post-stage power converter. In order to simplify the control, the switch of the pre-stage power converter is omitted, only one switch of the post-stage power converter is adopted to perform synchronous control. Since the multiple sets of power conversion circuits in the previous stage are connected in series, the turn ratio of the transformer in the power converter in the subsequent stage can be reduced. Therefore, the transformer can be miniaturized and the power supply circuit would be more suitable for agricultural plant protection machine and electrostatic spray apparatus.