With the rapid development of the world economy, energy demand has surged. The energy crisis and environmental pollution are becoming more and more serious, and it is urgent to vigorously develop renewable energy. Among them, photovoltaic power generation is also an important part of new energy. Therefore, single-phase off-grid inverters and their control of photovoltaic power generation systems have gradually become a research focus in recent years. The control method adopted by the existing off-grid inverter is generally voltage single-loop instantaneous value feedback control, but this method has poor voltage following fastness and low accuracy.
Technical realization elements: The purpose of the present invention is to provide a vector control method for a single-phase off-grid inverter. The single-phase off-grid vector control inverter method calculates virtual components and has a fast dynamic response speed. In order to achieve the above objective, the present invention provides a single-phase off-grid vector control inverter method.
The vector control method includes:
Step 1: Use single-phase phase-locked loop technology to phase-lock the reference voltage Uref to obtain the phase θ, delay the reference voltage Uref by 1/4 cycle to obtain the virtual signal Urefv, and perform the rotation coordinate transformation on the reference voltage Uref and the virtual signal Urefv to obtain respectively the rotating reference voltage Udref and the virtual rotating reference voltage Uqref in the rotating coordinate system;
Step 2: Collect the single-phase output voltage Us in real time, obtain the virtual voltage Um by delaying the output voltage Us by 1/4 cycle, and perform the rotation coordinate transformation on the single-phase output voltage Us and the virtual voltage Um to obtain the rotating voltage Ud and the virtual rotation in the rotating coordinate system Voltage Uq;
Step 3: After comparing the rotation voltage Ud and the virtual rotation voltage Uq with the rotation reference voltage Udref and the virtual rotation reference voltage Uqref, the proportional integral regulator is used to obtain the d-axis voltage control value Udr and the q-axis voltage control value Uqr. The d-axis voltage control value Udr and the q-axis voltage control value Uq perform static coordinate transformation to obtain the real-axis control variable Vs and the imaginary-axis control variable Vm; the real-axis control variable Vs is provided to the main circuit through the PWM generator.