PV Microconverter MPPT Using Bypass Diode Prediction
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Solution Overview
Problem
Conventional photovoltaic (PV) systems with string inverters underperform due to partial shading, non-uniform illumination, and module mismatches, as existing MPPT algorithms are confused by local power maxima and require extensive scanning, and lack continuous mode switching efficiency.
Innovation Solution
The use of bypass diodes in PV modules to predict local maxima locations, allowing for quick power measurements to initiate a perturb and observe (P&O) algorithm, and implementing a microcontroller-programmed dc-dc microconverter system for continuous maximum power point tracking between buck and boost modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional MPPT algorithms scan the entire power range to identify maxima, then they can find the maximum power point, but they require large amounts of time and are confused by local maxima
Solution Approach 1:
The patent applies preliminary action by using bypass diode characteristics to predict the locations of power maxima before performing measurements. By calculating expected maxima positions based on diode voltages and module configuration, the system avoids scanning the entire power range and directly targets likely maximum points, significantly reducing scanning time while maintaining identification accuracy.
2Adaptability or versatility
If perturb and observe algorithm is used to track maximum power point, then continuous tracking is achieved, but large adjustment times are required when shading or conditions change
Solution Approach 1:
The system performs preliminary identification of the true maximum power point location using bypass diode characteristics before initiating perturb and observe tracking. This preliminary positioning ensures that when environmental conditions change, the algorithm starts from the correct maximum point rather than requiring large adjustments from an incorrect starting position, thereby reducing adjustment time while maintaining continuous tracking capability.
3Loss of energy
If MPPT algorithms do not provide continuous switching between power modes, then mode switching efficiency is reduced, but the system requires relatively large components for compensation
Solution Approach 1:
The patent implements dynamic continuous switching between buck and boost power modes based on real-time operating conditions. The control system continuously adjusts the power conversion mode to match load and source conditions, eliminating energy losses associated with discrete mode transitions. This dynamic approach allows the use of smaller compensation components while maintaining high switching efficiency, as the system adapts smoothly rather than switching abruptly between fixed modes.
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 enables rapid and accurate determination of the maximum power point, reducing scanning time and enhancing efficiency by allowing seamless mode switching, resulting in high efficiency and compact form factor with synchronous rectification and reduced component size.
Implementation Method 1
PV modules possess bypass diodes to prevent damage caused by partial shading conditions. If one uses knowledge of the number of diodes in the module along with a measurement of the module open circuit voltage, then one can reliably predict the vicinity where all possible local maxima can occur.
Data Source
AI summary
Series strings of photovoltaic (PV) modules with integrated dc-dc microconverters that can function in buck, boost, or an intermediate bridge mode based on the load can harvest more energy than conventional central-inverter architectures, especially when the arrays are partially shaded or when the modules are mismatched. The integrated multi-mode dc-dc converter includes a maximum power point tracking (MPPT) algorithm that can track the true MPP, even when a PV module becomes partially-shaded, without scanning the entire output voltage range. The algorithm compares power levels only at a voltage that occurs when a bypass diode bypasses a portion of an associated PV module, and multiples thereof.