Energy Combiner Circuit for 3 kV PV Bus Cable Reduction
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Solution Overview
Problem
The high current on the direct current bus and large cable diameter, leading to increased costs in photovoltaic power systems due to the maximum voltage limitation of 1500 V, result in high cable costs when connecting multiple photovoltaic panels.
Innovation Solution
A power supply system design that includes a solid-state transformer with a novel energy combiner apparatus, utilizing DC/DC conversion units to increase output voltage to 3 kV while maintaining within the 1500 V panel specification, reducing the current and cable thickness, and incorporating filter units to manage ripple current frequency, thereby reducing overall system costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If photovoltaic panels are connected in parallel to increase power output, then the current on the direct current bus increases, but the cable diameter and costs increase
Solution Approach 1:
The patent changes the voltage parameter from the conventional 1500V maximum to a higher voltage level by using series connection of photovoltaic panels. This parameter change allows the system to maintain the same power output with lower current, thereby reducing cable diameter and associated costs while avoiding the need for expensive high-voltage cables through a different architectural approach
2Reliability
If the maximum voltage is limited to 1500 V for panel safety, then the system operates safely, but the current increases leading to larger cable requirements and higher costs
Solution Approach 1:
The patent segments the photovoltaic system into multiple series-connected panels that operate at higher individual voltages, which are then combined through the energy combiner apparatus. This segmentation allows each panel to operate within safe voltage limits while the overall system achieves higher voltage output, reducing current and cable thickness requirements without compromising panel safety
Solution Approach 2:
The patent introduces a new dimensional approach by implementing a two-stage voltage transformation: first increasing voltage through series connection of panels, then further transforming it through the energy combiner apparatus with DC/DC conversion units. This dimensional change in voltage transformation methodology enables the system to overcome the 1500V limitation while maintaining panel safety and reducing cable requirements
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
The system reduces cable thickness and costs by optimizing voltage and current distribution, while minimizing filter capacitance requirements, thus enhancing efficiency and cost-effectiveness.
Implementation Method 1
a DC/DC conversion unit having a unidirectional step-up direct current conversion function
Implementation Method 2
utilizing DC/DC conversion units to increase output voltage to 3 kV while maintaining within the 1500 V panel specification
Implementation Method 3
incorporating filter units to manage ripple current frequency
Data Source
Figure 1
Figure 2
Figure 3~4a
AI summary
Embodiments of this application provide a power supply system, to resolve technical problems in the conventional technology that a current on a direct current bus is high, a diameter of a cable is large, and costs of the cable are high. In embodiments of this application, the energy combiner apparatus is used to convert output of a power supply, and has three output terminals, so that output ports are increased. In the three output terminals of the energy combiner apparatus, a voltage of 1500 V is output between a first output terminal and a second output terminal, a voltage of 1500 V is also output between the second output terminal and a third output terminal, and a total of 3 kV is output. Therefore, an overall output voltage is increased in a case of equal output power. Because the overall output voltage is increased, a current transmitted on a cable may be reduced. Therefore, a thinner cable may be used, so that costs of the cable are reduced. In addition, four cables conventionally required for connecting to the output terminals of the energy combiner apparatus are reduced to three cables, so that a quantity and costs are reduced.