Variable Step Width MPPT Control for Power Converters
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Solution Overview
Problem
Conventional Maximum Power Point Tracking (MPPT) methods for power converters, such as those used in solar power generation, are inefficient due to slow search times and require multiple control adjustments, leading to power generation losses and instability, especially when dealing with rapid power changes and harmonic restrictions.
Innovation Solution
A control device for power converters that includes a searching unit to adjust the operation voltage or current in predetermined steps, a consecution time determining unit to assess consecutive changes, and a step width increasing unit to increase the step size when a predetermined number of consecutive changes have occurred, allowing for faster search times and reduced power generation losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the voltage step width is kept within a given certain range to ensure stable control, then the control stability is improved, but the searching time increases resulting in power generation loss
Solution Approach 1:
The patent applies dynamics by making the voltage step width variable rather than fixed. The step width is dynamically adjusted based on the search progress: initially set to a first value for fast searching, then changed to a second value when approaching the maximum power point. This dynamic adjustment resolves the contradiction by allowing fast searching early on while ensuring precise control near the optimal point.
Solution Approach 2:
The patent changes the parameter of voltage step width from a constant value to a variable value that changes based on search conditions. By monitoring whether the power increase amount exceeds a threshold, the system automatically adjusts the step width parameter, thereby achieving both fast searching and stable control without the trade-off present in conventional fixed-step methods.
2Productivity
If the voltage and current are changed at fast speed to reduce searching time, then the productivity is improved, but the generated power changes rapidly producing harmonic
Solution Approach 1:
The patent uses dynamic adjustment of the voltage step width to control the speed of power changes. By starting with a larger step width for fast searching and then reducing it when near the maximum power point, the system achieves high productivity during searching while minimizing rapid power changes that would generate harmonic, thus resolving the contradiction between searching speed and harmonic generation.
3Measurement precision
If the derivative value threshold is used to determine maximum power point to reduce capacitance parasitic effect, then the measurement precision is improved, but multiple control adjustments are necessary increasing searching time
Solution Approach 1:
The patent changes the detection parameter from derivative-based (requiring multiple adjustments) to power increase amount-based. By monitoring whether the power increase exceeds a predetermined threshold when voltage is incremented, the system directly identifies the maximum power point in fewer steps, improving both detection accuracy and reducing searching time compared to derivative threshold methods.
Data Source
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AI summary
A control device includes a searching unit 31 increasing or decreasing, at a predetermined step width, an operation voltage or an operation current of a power supply 200 connected to a power converter 400 to search a maximum power point of the power supply 200, a consecution time determining unit 32 determining whether or not the searching unit 31 has consecutively increased or decreased the operation voltage of the power supply 200 or the operation current thereof, and a step width increasing unit 33 increasing the step width upon determination by the consecution time determining unit 32 that the increase or the decrease has been consecutively executed by a predetermined number of times.