This section focuses on the application of fuzzy control in grid-connected solar inverters, aiming to improve the performance and reliability of solar inverters. Fuzzy control is a powerful tool that can handle the nonlinear and uncertain characteristics of photovoltaic systems.
1. Introduction
Fuzzy controllers are widely used in solar inverters due to their simple algorithm implementation, low processor requirements, and good universality for nonlinear systems. The basic design idea of fuzzy control in solar inverters is to select appropriate input and output variables based on the type and control target of the solar inverter, and describe the relationship between input and output variables through fuzzy rules.
2. Analysis of Boost Converter Based on Fuzzy Control
- Fuzzy Control Strategy Analysis of Boost Converter : The Boost converter is an important part of the solar inverter, which is responsible for adjusting the input voltage to meet the requirements of the solar inverter. The fuzzy logic control method is used to realize the maximum power point tracking of the Boost converter.
- Fuzzy Control Algorithm Design of Boost Converter : A detailed fuzzy control algorithm is designed for the Boost converter, including the definition of input and output variables, the selection of membership functions, and the formulation of fuzzy rules. The algorithm is based on the model of the Boost converter and the characteristics of the photovoltaic cells.
3. Research on Solar Inverter Based on Fuzzy Control
- Establishment of Inverter Mathematical Model : The mathematical model of the voltage source input and current source output control mode of the single-phase grid-connected solar inverter is established, which is the basis for the design of the fuzzy controller.
- Design of Fuzzy Controller for Inverter : A fuzzy controller is designed for the solar inverter based on the fuzzy model. The input variables of the controller are the grid voltage, current error, reference current, and reference current differential, and the output variable is the duty cycle of the inverter power switch.
- Improvement of the Control Algorithm : To overcome the problem of large current tracking ripple at the zero-crossing point of the traditional fuzzy control algorithm, an improved control strategy is proposed by slightly adjusting the control strategy of the power switch.
4. Simulation Verification
A complete simulation model of the current tracking type single-phase grid-connected solar inverter based on fuzzy control is established in the simulation environment. The normal operation and fault conditions of the solar inverter are simulated, and the output current and voltage waveforms are analyzed. The following table summarizes the simulation results under different conditions:
| Condition | Output Current Waveform | Voltage Waveform | Harmonic Distortion Rate |
|---|---|---|---|
| Normal operation | Sinusoidal, in phase with the grid voltage | Sinusoidal | Low |
| Grid voltage mutation | Stable, quickly tracks the reference current | Sinusoidal with some disturbance | Low |
| Reference current mutation | Quickly tracks the new reference value | Sinusoidal | Low |
The simulation results show that the fuzzy control strategy has good current tracking effect and fast response speed, and can effectively suppress the harmonic distortion of the output current.
5. Conclusion
This section proposes a set of fuzzy control methods for grid-connected solar inverters, which avoids the dependence on expert experience and the repeated debugging of membership functions and adjustment factors in the existing fuzzy control algorithms. The simulation results verify the effectiveness of the control strategy in improving the performance and reliability of the solar inverter.
By using tables to summarize the simulation results and comparisons, the content becomes more clear and intuitive. Additionally, avoiding the use of mathematical formulas and pictures makes the text more accessible to readers who may not have a strong mathematical background.