DC Voltage Control in Renewable Energy Multilevel Power Converter
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Solution Overview
Problem
Traditional PV inverters face challenges in efficiently balancing DC voltage between split DC buses and mitigating inrush transients, which can lead to electrical stress and component damage, and integrating power systems with high voltage components is difficult due to high conversion requirements and high costs.
Innovation Solution
A renewable energy-based power converter architecture that includes a 3-level neutral-point clamped inverter, interface converters, auxiliary DC-DC converters, and a controller for voltage balancing and regulation, which performs DC bus balancing, voltage regulation, and pre-charge functions to reduce inrush current and enhance DC-bus voltage utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If traditional PV inverter architecture is used, then simplicity of design is maintained, but DC voltage balancing capability deteriorates
Solution Approach 1:
The DC bus is segmented into high-side and low-side DC buses with separate capacitors, allowing independent voltage control and balancing. The interface converter is divided into first and second circuit portions that independently manage each DC bus, enabling precise voltage regulation and balancing capability.
2Power
If high voltage components are integrated, then power handling capability is improved, but conversion requirements and cost increase
Solution Approach 1:
The system changes voltage parameters through controlled conversion rather than relying on high voltage components. The interface converter regulates voltages on high-side and low-side DC buses to appropriate levels, enabling standard components to handle high power through intelligent voltage management rather than physical high voltage ratings.
3Ease of manufacture
If simple inverter architecture is used, then manufacturing cost is reduced, but inrush transient mitigation capability deteriorates
Solution Approach 1:
The interface converter performs preliminary voltage regulation and balancing before the main inverter operates. By pre-establishing proper voltage levels on both DC buses and mitigating inrush transients in advance, the system protects components from electrical stress without requiring complex protective circuitry in the main inverter 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
The architecture effectively balances DC voltages, reduces inrush current, and extends DC-bus voltage utilization, improving the efficiency and reliability of renewable energy-based multilevel power converters while reducing component stress and costs.
Implementation Method 1
an inverter portion coupled to the high-side DC bus and the low-side DC bus and configured to convert DC power from the high-side DC bus and the low-side DC bus into output AC power
Implementation Method 2
the controller is configured to operate the interface converter to convert DC power from the high-side DC bus and the low-side DC bus into regulated DC power having a regulated DC voltage level
Data Source
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AI summary
According to one aspect, embodiments herein provide a renewable energy-based power converter comprising an input, a high-side DC bus, a low-side DC bus, a first output, an inverter portion configured to convert DC power from the high-side DC bus and the low-side DC bus into output AC power, an interface converter coupled to the high-side DC bus and the low-side DC bus, a first auxiliary DC-DC converter, and a controller, wherein, in a first mode of operation, the DC busses are configured to receive input DC power from the input, and the controller is configured to operate the interface converter to convert DC power from the DC busses into regulated DC power, to operate the interface converter to balance voltage levels of the DC busses, and to operate the first auxiliary DC-DC converter to convert the regulated DC power into first output DC power provided to a DC load.