Power Converter Modulation for Low Light Energy Capture
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Solution Overview
Problem
Power converters for renewable energy systems face inefficiencies at low power generation levels, leading to increased energy losses and the need for a converter that can operate effectively across a wide range of power levels, especially in low light conditions.
Innovation Solution
A power converter with a modulation module that selectively connects switching devices between a photovoltaic array and a DC bus, operating in multiple modes: one with a fixed modulation period and variable on time, and another with a variable modulation period and fixed on time, allowing for efficient energy capture and reduced losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the power converter operates at low power generation levels, then energy capture is enabled, but energy losses increase and exceed the power being generated
Solution Approach 1:
The patent implements dynamic switching between two operating modes based on real-time power generation levels. The controller monitors the DC voltage and dynamically adjusts the modulation strategy: using fixed frequency PWM at higher power levels and variable frequency PWM at lower power levels, optimizing efficiency across the entire operating range
Solution Approach 2:
The patent changes the operating parameters of the power converter by implementing two distinct modulation modes. The first mode uses fixed frequency with variable duty cycle, while the second mode uses variable frequency with fixed duty cycle. This parameter adaptation allows the converter to maintain efficiency across varying power generation conditions
2Loss of energy
If the power converter is switched off to avoid energy losses exceeding generation, then energy losses are reduced, but energy capture capability is lost
Solution Approach 1:
Instead of binary on/off operation, the system dynamically adapts its operating mode based on real-time conditions. The controller continuously monitors power generation levels and switches between two modulation strategies, enabling the converter to operate efficiently across a wide range of power levels rather than simply being on or off
3Measurement precision
If the power converter operates with fixed modulation period and variable on time, then control precision is improved, but adaptability to varying power levels is reduced
Solution Approach 1:
The power converter is designed with multi-functionality by implementing two distinct operating modes within a single device. The controller can selectively activate either fixed-frequency mode or variable-frequency mode depending on the operating conditions, making the converter universally applicable across the entire power generation range
4Adaptability or versatility
If the power converter operates with variable modulation period and fixed on time, then adaptability to low power levels is improved, but control precision is reduced
Solution Approach 1:
The patent changes the modulation parameters dynamically based on operating conditions. In the second operating mode, the system uses variable frequency with fixed duty cycle, which provides better adaptability to low power levels by allowing the switching frequency to adjust according to the available power generation
Data Source
AI summary
A power converter is configured to transfer energy from a photovoltaic (PV) array to a DC bus internal to the power converter. The power converter executes a modulation module to selectively connect one or more switching devices between the output of the PV array and the DC bus. The power converter is configured to operate in multiple operating modes. In one operating mode, the converter operates with a fixed modulation period and a variable on time, and in another operating mode, the converter operates with a variable modulation period and a fixed on time. The improved power converter provides highly efficient low power energy capture, improving power efficiency and enabling energy capture in low light conditions with reduced converter losses.