Design and implementation of real time MPPT

In our Project, we are designing an MPPT (Maximum Power Point Tracking device) for solar panels. MPPT solar charge controller extracts maximum power from the PV module.  Maximum power varies with solar radiation, ambient temperature, and solar cell temperature. MPPT checks

Project Title

Project Area of Specialization

Electrical/Electronic Engineering

Project Summary

In our Project, we are designing an MPPT (Maximum Power Point Tracking device) for solar panels. MPPT solar charge controller extracts maximum power from the PV module. Maximum power varies with solar radiation, ambient temperature, and solar cell temperature.

MPPT checks the output of the PV module, compares it to battery voltage then fixes what is the best power that the PV module can produce to charge the battery and converts it to the best voltage to get maximum current into the battery. It can also supply power to a DC load, which is connected directly to an MPPT.

An MPPT solar charge controller is the charge controller embedded with an MPPT algorithm to maximize the amount of current going into the battery from the PV module.

MPPT consists of two parts:

Converter
Algorithm

Converter

Examples of DC to DC converters are:

Boost converter

The boost converter is a power converter in which DC input voltage is less than DC output voltage. That means PV input voltage is less than the battery voltage in the system.

Buck converter

The buck converter is a power converter in which DC input voltage is greater than DC output voltage. That means PV input voltage is greater than the battery voltage in

Interleaved buck converter

The interleaved synchronous buck converter is a popular solution to supply high-current microprocessors because of the lower input and output current ripple and higher operating frequency of input and output capacitors in comparison with the one-channel solution.

Converter used in our Project

The converter which we are using in our project is a two-phase synchronous inter-leaved buck converter.
The converters are controlled by interleaved switching signals (in our project given by driver ICs), which have the same switching frequency but a shift in phase. Using interleaved converter we can get improved efficiency, reduced ripple voltage, reduced inductor current ripple, and fast switching speed.
This converter also provides a maximum current of 20A at the output and has fewer ripples at the output.

Algorithm

The algorithm which we are using is the P&O algorithm.
There are many other algorithm techniques but we are using the P&O method because it is the simplest method that moves the operating point toward the maximum power point periodically increasing or decreasing the PV array voltage.
In this technique, a minor perturbation is introduced to, cause the power variation of the PV module. The PV output power is periodically measured and compared with the previous power for tracking MPP (Maximum power point).

Project Objectives

To design Maximum Power Point Tracking (MPPT) for solar charge controller. For this purpose, MPPT solar charge controller adjusts the output power of the DC converter.
For a given irradiance, the MPPT technique extracts the maximum power available in PV arrays.
To optimally utilize the energy available from the connected solar module arrays at any time during its operation.
To digitally implement the MPPT solar charge controller, the parameters vary with time and adjustment of controller becomes vital. Digital implementation gives opportunity to make such changes at any time.
Optimization at both algorithm and converter levels.

Project Implementation Method

First, we have studied all the maximum power point tracking (MPPT) algorithms as well as the converters supporting the dc level shift. Based on various performance factors we choose perturb and observe MPPT algorithm, and two-phase synchronous interleaved buck converter.

Second, the design of MPPT (converter and algorithm) is verified using MATLAB/SIMULINK simulation. Since the project comprises tens of components including a microcontroller chip, the spice simulation is not realistic. Therefore, the final test of the hardware will be rather crucial.

Then, the MPPT algorithm is written in c language to be deployed in the microcontroller. For the hardware part, including schematic and PCB design, the ALTIUM DESIGNER is used. One of the major limitations in the implementation steps is that the majority of components in the BOM are not available in the local market and will be imported. This not only adds to the cost but also delays the implementation,

Then we have written an algorithm for controlling each and every component (gate driver ICs/ sensors/regulators etc) used in our project.

Benefits of the Project

Improve the efficiency of the charge controller.
Ability to operate for a wider range of input
Protection against battery reverse polarity, over-charge, and over-discharge protections. Increasing letting the battery work over a longer span of time.
Failure protection in case of system over-temperature.
Ambient Light Detection is also a vital feature of our project.

Technical Details of Final Deliverable

This reference design is a Maximum Power Point Tracking (MPPT) solar charge controller for 12-V, 24-V, and 48-V solar panels. This compact reference design targets small and medium-power solar charger solutions and is capable of operating with 15 to 60-V solar panel modules, 12-V, 24-V, or 48-V batteries, and providing upwards of 20-A output current. The design uses a two-phase interleaved buck converter to step down the panel voltage to the battery voltage. The buck converter and its connected gate drivers are controlled by a microcontroller unit, which calculates the maximum power point using the perturb and observe method. The solar MPPT charge controller is created with real-world considerations, including reverse battery protection, software programmable alarms and indications, and surge and ESD protection.