Photovoltaic MPPT Finite-State Machine Target Range Search
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Solution Overview
Problem
Existing photovoltaic generators face inefficiencies in tracking the maximum power point due to current mismatches caused by partial shading and environmental changes, leading to energy losses as conventional MPPT techniques like Perturb-and-Observe may converge slowly or inaccurately, especially in concentration-type systems with rapidly varying power-voltage characteristics.
Innovation Solution
A method that determines a target range for the maximum power point by comparing relative critical mismatches between photovoltaic generator ranges, allowing for efficient tracking within this range, reducing the number of iterations and energy losses, and enabling fast and accurate convergence even under quick voltage changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If Perturb-and-Observe method is used for MPPT control, then the implementation is simple, but the convergence speed is slow and accuracy is reduced due to operating at relative power peaks
Solution Approach 1:
The patent applies preliminary action by performing a preliminary search of the power-voltage characteristic curve before initiating the Perturb-and-Observe method. This search identifies the correct operating range and absolute maximum power point, allowing the subsequent MPPT algorithm to converge faster and more accurately without wasting time exploring incorrect regions of the curve.
Solution Approach 2:
The patent segments the power-voltage characteristic curve into multiple ranges based on relative power peaks. By dividing the search space into segments and identifying which segment contains the absolute maximum, the system can focus its MPPT efforts in the correct region, improving both convergence speed and accuracy while maintaining algorithmic simplicity.
2Measurement precision
If Perturb-and-Observe method is used with high frequency and low pitch displacements, then convergence accuracy improves, but convergence speed decreases and energy losses increase
Solution Approach 1:
The patent applies dynamics by making the displacement frequency and pitch adaptive rather than fixed. The system dynamically adjusts these parameters based on the operating conditions and the stage of convergence. During preliminary search, higher frequency and larger pitch are used for fast exploration; during fine-tuning near the maximum, frequency is reduced and pitch is optimized for precision, thereby reducing overall convergence time and energy losses.
3Measurement precision
If search for maximum power point is performed whenever environmental conditions change substantially, then the maximum power point is accurately tracked, but considerable energy losses occur during the search
Solution Approach 1:
The patent applies local quality by focusing the search effort locally around the expected maximum power point region rather than performing a global search of the entire power-voltage curve. By using environmental condition data to predict the likely operating range and concentrating the search in this local region, the system achieves accurate tracking while minimizing the time and energy spent during search operations.
4Duration of action of stationary object
If conventional MPPT techniques are used, then the system operates continuously, but energy losses occur due to operation away from the actual maximum power point
Solution Approach 1:
The patent applies preliminary action by performing an initial comprehensive search and identification of the absolute maximum power point before starting continuous MPPT operation. This preliminary characterization of the power-voltage curve allows the system to establish accurate reference points and operating ranges, enabling subsequent continuous operation to remain consistently near the true maximum power point and thereby minimizing energy losses from suboptimal operation.
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 approach significantly reduces energy losses by quickly and accurately tracking the maximum power point, improving energy efficiency and mitigating errors caused by environmental variations, particularly in concentration photovoltaic systems.
Implementation Method 1
The photovoltaic generators are commonly used to convert light energy into electrical energy
Data Source
Figure 1
Figure 2A~2B
Figure 2C~2D
AI summary
The invention pertains to a control logic of a photovoltaic generator for tracking its maximum power point. The control logic is performed by a finite-state machine. The finite-state machine starts a total searching procedure of a target range CRtarget in which the maximum power point occurs. The finite-state machine passes from the state 505 to a state 510 for determining a starting range CRstart, whose mismatch CRstart is lower than or equal to an absolute critical mismatch Mca. The finite-state machine passes from the state 510 to a state 515 for determining the mismatch Mstart of the starting range CRstart. The finite-state machine then passes from the state 515 to a state 520, during which the relative difference of the mismatches Mstart+d and Mstart is compared to the corresponding relative critical mismatch Mcr(d). If the relative difference of the mismatches Mstart+d and Mstart is lower than the relative critical mismatch Mcr(d), the starting range CRstart is moved to the following range CRstart+d and the finite-state machine returns to the state 515 to repeat the same operations, until the target range is identified.