Photovoltaic MPPT via Conductance Logarithm Lookup
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Solution Overview
Problem
Existing maximum power point tracking (MPPT) systems for photovoltaic power sources are complex, require substantial processing power, and may struggle to accurately track the maximum power point due to iterative calculations and inability to discern between local and global maxima, leading to inefficiencies and potential power loss.
Innovation Solution
A method and system that adjust the operating parameter of a load connected to a photovoltaic power source by calculating the logarithm of conductance from voltage and current measurements, comparing it to a reference setpoint, and incrementally modifying the parameter using a fuzzy control system to maintain the maximum power point, with the ability to adjust based on rate of change and direction of error.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If iterative MPPT calculations are used to track maximum power point, then power tracking accuracy is improved, but processing time increases and system complexity increases
Solution Approach 1:
The patent pre-calculates and stores conductance values and their corresponding maximum power point voltages in lookup tables during system initialization or calibration phases. During operation, the controller simply queries these pre-computed tables based on measured conductance, eliminating the need for real-time iterative calculations and achieving instant MPP tracking without processing delays
Solution Approach 2:
The patent creates a simplified mathematical model or lookup table that copies the essential relationship between conductance and maximum power point voltage. Instead of performing complex iterative calculations on the actual system, the controller uses this pre-established model to directly determine operating parameters, achieving accurate MPP tracking with minimal computational overhead
2Measurement precision
If iterative MPPT calculations are used to track maximum power point, then power tracking capability is improved, but device complexity increases
Solution Approach 1:
The patent extracts the complex iterative calculation logic from the real-time control loop and separates it into pre-computed lookup tables or simplified relationships. The runtime system only needs to perform simple table lookups or basic calculations based on measured conductance, dramatically reducing the computational complexity and processing requirements of the control system
Solution Approach 2:
The patent transforms the control approach from using complex iterative algorithms to using pre-calculated conductance-voltage relationships. By changing the control parameter from requiring iterative optimization to using direct conductance-based lookup, the system achieves MPP tracking with significantly reduced computational complexity and simpler hardware requirements
3Measurement precision
If multiple calculated metrics are compared in MPPT system, then power tracking accuracy is improved, but processing power requirement increases
Solution Approach 1:
The patent extracts and removes the need for multiple complex metric calculations by focusing solely on conductance measurements. The system compares measured conductance against pre-stored conductance values in lookup tables, eliminating the need for multiple simultaneous calculations and reducing processing power requirements to minimal levels
Solution Approach 2:
The patent uses a simplified approach that performs only the necessary conductance measurement and comparison operations, rather than calculating multiple metrics. This partial action approach achieves sufficient MPP tracking accuracy by focusing on the critical conductance parameter while deliberately omitting unnecessary calculations, thereby reducing processing power consumption
Data Source
AI summary
A method is provided for setting an operating parameter for a load on a photovoltaic power source, such as an AC signal or the speed of a motor, including operating a load, using a control system, with the operating parameter set at a first value, providing a measurement of DC source voltage at the power source to the control system, and providing a measurement of DC source current at the power source to the control system, determining the logarithm of the conductance from the measurement of DC source voltage and the measurement of DC source current, and comparing a reference parameter based on the logarithm of the conductance to a reference setpoint. Based on that comparison, the operating parameter may be modified for the load if the value of the reference parameter differs from the value of the reference setpoint by more than a threshold amount.