Research And Implementation Of Current Type Photovoltaic Grid-Connected Inverter Controller

With the rapid development of economy, the human civilization has made a great progress. So the human's conscious of environment protection is enhancing. Solar power technology has been favored by people because of the solar has the advantage which it is clean, cheap and have rich reserves. The grid-connected inverter has become core of the solar power generation system. Today, the digital technologies develop rapidly. The dedicated chip digital signal processor (DSP) has appeared, it ensures the advanced control strategies achieved in digital system. The photovoltaic grid-connected inverter controller is maded a detailed description in this paper. In the other way, the maximum power point tracking, grid-connected control strategy and the design of the phase locked loop are studyed in depth in this paper.The photovoltaic power generation background, many topologies of the photovoltaic power generation systems and the technology of inverter are introduceded in detail in this paper at firstly. Then the topology and control system of the grid-connected inverter controller are analyed.Based on this, the grid-connected control system hardware is designed in paper. The main circuit of this grid-connected control system contains two parts, which are the DC/DC converter circuit and inverter filter circuit. In the circuit of DC/DC, the voltage is enhanceded by the Boost circuit. Behind of the Boost circuit, there are inverter circuit and grid-connected filter circuit. Another important factor is the phase lock loop (PLL), it ensure the grid-connected electric current's frequency and the phase same as the voltage of the power grid. In the design of the system, the main circuit and the control circuit is designed in different circuit boards. In this way, the strong electromagnetic interference is eliminated. There are processor core circuit, the signal conditioning circuit, sampling circuit and power supply circuit in the control circuit board. The detail deduction and calculation in this paper in order to ensure the parameters of various devices. At the same time, a new maximum power tracking method is designed in this papers, it is the variable step-size discontinuous disturbance method. This method is base on the constant voltage method and conductance increment method. The PID control method and the neural network combination are used to the main circuit to control the circuit output. In the grid-connected, a new phase lock loop is designed ensure the grid-connected electric current have the same frequency and phase as the grid voltage. This phase lock loop contains two comparisons function and the automatic regulation function.Finally, the whole system is assembled and debugging. The experimental results show that using electric current tracking network voltage has a good effect, and it achieve the grid connection requirements.