Photovoltaic Inverter with MPPT Using Solar Explorer Kit

Required Hardware

Available Models

Simulate the Photovoltaic Inverter with MPPT

The simulation model consists of the plant model and the controllers. The plant model consists of three major components:

The controllers in the simulation model are:

To make a solar panel energy efficient, the panel must be operated at its maximum power point. However, the maximum power point is not fixed because of the nonlinear nature of the PV cell and changes in temperature and light intensity. The perturb & observe (P&O) algorithm is implemented using a Stateflow® chart for calculating the reference voltage required for maximum power point operation. The reference voltage is achieved with the help of the DC-DC boost controller. The DC-DC boost controller implements a PI controller to track the reference voltage set by the MPPT algorithm. For tracking the reference voltage, the PV panel voltage (Vpv) is measured.

The DC-DC boost converter is a traditional single-phase converter with a single switching MOSFET, Q1. The duty cycle of the PWM output that drives Q1 determines the amount of boost imparted to the controlled parameter.

The DC-DC boost controller is realized using a PI controller. An increase in the duty cycle of the boost converter loads the panel and results in a panel output voltage drop. Accordingly, an increase in the output of the controller (duty cycle of the boost converter) causes an increase in the error input to the controller. To achieve the reference voltage value, the feedback and the voltage reference inputs of the PI controller are reversed. The controller operates at a rate of 50 kHz.

The DC-DC boost converter output voltage is not controlled using the DC-DC boost controller. However, the boost converter output voltage is regulated by the DC-AC inverter controller, which modulates the current drawn by the DC-AC inverter to keep this voltage regulated. The DC-AC inverter controller uses nested control loops — an outer voltage loop and an inner current loop.

The voltage loop generates the reference for the current loop. An increase in the current loads the DC bus and therefore causes a drop in the DC bus voltage. To achieve the reference voltage value, the feedback and the outer voltage compensator reference are reversed. The current reference is then multiplied by the sine reference to get the instantaneous current reference. The instantaneous current reference is then used by the current compensator along with the feedback current to provide duty cycle for the DC-AC inverter. The duty cycle is calculated using the unipolar sine PWM technique.

The input to the PV emulator can be changed to run the simulation for different values of irradiance. The controller parameters can be tuned to get a refined performance.

Generate Code for the Controller and Load It on the ControlCARD

The deployment model consists of three real-time interrupt service routines (ISR) used for:

The F28035 processor receives the irradiance value through serial communications interface (SCI) and sends it to the F28027 processor (PV emulator on the Solar Explorer Kit) using serial peripheral interface (SPI) communication. The F28027 processor is preconfigured to receive the updated irradiance value from the F28035 processor.

Monitor Signals and Tune Parameters Using the Host Computer

The host model receives the data from the kit and plots it to verify the performance of the MPPT and the control algorithms.

Monitor the Signals

While the model runs, you can monitor the Actual Panel Power signal on the scope. Actual Panel Power is the real-time power supplied by the PV emulator.

Tune the Parameters

While the model runs, you can tune parameters using the dashboard blocks:

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