Photovoltaic Air-Conditioner Switching Circuit for Inverter Current Isolation
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Solution Overview
Problem
The existing photovoltaic air-conditioning systems interfere with the normal control of the grid-connected inverter current due to simultaneous connection of the rectification and inverter circuits with the power grid, causing interference between the grid-connecting and inverting units.
Innovation Solution
A photovoltaic air-conditioning system comprising a switch module, an inverter circuit, a rectification circuit, and a compressor inverter, where the switch module controls the connection between the power grid and the photovoltaic battery or the air conditioner compressor, ensuring that the rectification and inverter circuits are not simultaneously conducting with the power grid, thereby preventing interference with the grid-connected inverter current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the rectification and PFC circuit is always connected to the power grid to ensure constant unity-power factor input, then the power factor correction is maintained, but the grid-connected inverter current control is interfered with when the photovoltaic battery supplies power
Solution Approach 1:
The power grid connection is segmented into two separate controllable paths: one through the rectification and PFC circuit, and another through the grid-connected inverter circuit. The switch module divides the single power grid input into two independent output channels, allowing selective connection of either the rectification circuit or the inverter circuit to the power grid, thereby preventing simultaneous operation and current control interference while maintaining power factor correction stability when needed
2Ease of operation
If the down bus of DC buses is connected to the live wire and neutral wire of the power grid through the rectification bridge, then the rectification circuit can input electric energy from the power grid, but the grid-connected inverter current flows into the down bus through the rectification bridge causing control interference
Solution Approach 1:
The harmful current flow path is extracted and eliminated by using the switch module to disconnect the rectification circuit from the power grid when the photovoltaic battery is supplying power. The switch module removes the problematic connection between the down bus and the power grid through the rectification bridge, preventing the grid-connected inverter current from flowing into the down bus and causing control interference, while allowing the rectification circuit to operate normally when it is the active power input path
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 effectively prevents mutual influence between the grid-connecting and inverting units, ensuring normal control of the grid-connected inverter current and enhancing the operational reliability of the photovoltaic air-conditioning system.
Implementation Method 1
the photovoltaic battery supplies power for a main circuit of an air conditioner
Implementation Method 2
the inverter circuit converts direct current in the DC buses to alternating current (AC) which is required for speed adjusting of the compressor
Implementation Method 3
the rectification and PFC (Power Factor Correction) circuit converts AC output from the power grid to DC
Data Source
Figure 1~2
Figure 3
AI summary
Disclosed are a photovoltaic air-conditioning system and a photovoltaic air conditioner having same. The photovoltaic air-conditioning system comprises a photovoltaic battery, a switch module, an inverter circuit, a rectification circuit and a compressor inverter; an input end of the switch module is electrically connected to a power grid; a first output end of the switch module is electrically connected to a first input/output end of the inverter circuit; a second output end of the switch module is electrically connected to an input end of the rectification circuit; an output end of the rectification circuit is electrically connected to an input end of the compressor inverter; the input end of the switch module is not simultaneously conducting with both of the first output end and the second output end of the switch module, and when the input end of the switch module is conducting with the first output end of the switch module, the power grid is connected to the photovoltaic battery; and when the input end of the switch module is conducting with the second output end of the switch module, the power grid is connected to a compressor of an air conditioner. By means of providing the switch module, a problem in an existing photovoltaic air-conditioning system of interfering with normal control of a grid-connected inverter current is effectively solved.