Simulation of PV-Based EV Charging Station with Five-Level Inverter

👋 Introduction

MATLAB/Simulink model of an EV charging station integrated with a renewable energy system (PV) and the single-phase grid. In this setup, the PV system is connected to the grid using a two-stage conversion (Boost Converter + Five-Level Multilevel Inverter) and it supports two EV charging units, each charging at 5 kW.

🧩 System Overview

This EV charging station model includes:

• ☀️ Solar PV Array (10 kW)

• ⬆️ Boost Converter with P&O MPPT

• 🔋 DC-Link Voltage Regulation (400 V)

• 🔄 Five-Level Multilevel Inverter + LCL Filter

• 🌐 Single-phase Grid (230 V, 50 Hz)

• 🏠 Local Home Load (2 kW)

• 🚗🚗 Two EV Batteries (each with bidirectional converter)

• 🔁 Energy management between PV and Grid

The system can operate in both directions:✅ If PV power is available → PV charges EV batteries✅ If PV power is low/zero → Grid supplies power to charge EV batteries

☀️ PV Array Design and Ratings

The PV array is sized for 10 kW charging station operation.

🔹 PV configuration

• Series modules: 6

• Parallel strings: 5

• Single panel rating: 350 W

🔹 Panel parameters at MPP

• ⚡ VMPP: 43 V

• 🔌 IMPP: 8.13 A

🔹 PV array performance

• 🌞 At 1000 W/m² → ≈ 10.48 kW

• 🌤️ At 500 W/m² → ≈ 5.19 kW

• ☁️ At 100 W/m² → ≈ 1 kW

This PV array is suitable for building rooftop EV charging applications such as multi-storey apartment charging hubs.

🔋 DC-Link Requirement (Why Boost Converter?)

At 1000 W/m², the PV array voltage is around 258 V, but to connect with a 230 V RMS grid, the inverter needs a higher DC-link voltage.

📌 Grid voltage

• RMS: 230 V

• Peak: 325 V

✅ Recommended DC-link voltage: ~400 V

So the PV voltage must be boosted:🔺 258 V → 400 VThis is achieved using a boost converter controlled by MPPT.

⬆️ Stage 1: Boost Converter with P&O MPPT

The first conversion stage consists of a boost converter controlled by the P&O MPPT algorithm.

🧠 P&O MPPT Working

📥 Inputs:

• PV voltage (Vpv)

• PV current (Ipv)

📤 Output:

• Reference voltage (Vref)

The MPPT logic:

• Calculates PV power

• Computes ΔV and ΔP

• Applies four P&O rules

• Updates Vref continuously

🎛️ Voltage Control for Boost Converter

• Vref is compared with Vpv

• Error processed using PI controller

• PI output gives duty cycle

• Duty compared with carrier waveform → PWM pulses

• PWM controls boost converter switch

✅ Outcome:

• Maximum PV power extraction

• DC-link voltage regulated near 400 V

🔄 Stage 2: Five-Level Multilevel Inverter for Grid Connection

The second stage is a hybrid five-level multilevel inverter connected to the grid through an LCL filter.

🔹 Features:

• Only five switches (S1–S5)

• Produces five voltage levels:

  • +Vdc

  • +Vdc/2

  • 0

  • −Vdc/2

  • −Vdc

✅ Advantages:

• Reduced harmonics

• Lower switching losses

• Better power quality

🎛️ Inverter Control Strategy (PI + PR + PLL)

🔹 DC-Link Voltage Control (Outer loop)

• DC-link voltage compared with 400 V

• Error processed using PI controller

• Output gives current reference magnitude

🔹 Grid Synchronization using PLL

• Grid voltage measured

• PLL generates ωt

• Produces sin(ωt) / cos(ωt)

🔹 Current Control using PR Controller (Inner loop)

• Reference current waveform created using sin(ωt)

• Compared with actual inverter current

• Error processed via PR controller

• Controller output added with grid voltage and normalized by Vdc

• Generates modulation index → switching pulses for five-level inverter

✅ Ensures:

• Synchronization with grid

• Accurate current injection/absorption

• Stable DC-link regulation

🏠 Local Home Load Integration

A local load is connected at the grid point:

• 🏠 Load rating: 2 kW

• Voltage: 230 V RMS

• Frequency: 50 Hz

This represents a real-life home/building load that must be supplied while EV charging continues.

🚗🚗 EV Battery Charging System (Two Chargers)

Two EV battery packs are included:

• 🔋 Battery voltage: 240 V

• 🔋 Capacity: 200 Ah (as per your model)

• Each EV has a bidirectional DC–DC converter

⚡ Charging Power Reference

Each EV is charged at:

• 5 kW

Reference current is computed as:

• Iref = 5 kW / Battery Voltage

🎛️ EV Charging Control (Current Control Mode)

For each EV:

• Battery current compared with Iref

• Error processed via PI controller

• PWM pulses generated

• Pulses drive the bidirectional converter switches

✅ Result:

• Each EV battery charges at constant 5 kW, whenever power is available

🌦️ Irradiance Variation and Energy Management

Irradiance is varied in steps:

• 1000 → 500 → 100 → 500 → 1000 W/m²(at different times like 0.5 s, 1.5 s, 2 s as per your script)

This demonstrates real-time power sharing between PV and grid.

📊 Working Principle (Power Sharing Logic)

✅ Case 1: PV = 10 kW (High Irradiance)

• PV supplies:

  • EV1 = 5 kW

  • EV2 = 5 kW

• Grid supplies only:

  • Local load = 2 kW

📌 Grid power ≈ 2 kWEV SOC increases continuously.

✅ Case 2: PV = 5 kW (Medium Irradiance)

PV can support only part of EV charging.

• PV supplies ≈ 5 kW (typically one EV)

• Remaining demand comes from grid

Total demand:

• EVs = 10 kW

• Home load = 2 kW➡️ Total = 12 kW

So grid supplies:

• (EV deficit + home load) ≈ 7 kW (as observed)

✅ Case 3: PV ≈ 0–1 kW (Low Irradiance)

PV becomes insufficient.

• Grid supplies almost entire demand:

  • EVs = 10 kW

  • Home load = 2 kW➡️ Grid ≈ 12 kW

This confirms grid-assisted EV charging during low solar conditions.

📈 Key Simulation Outputs Observed

During simulation you can monitor:

• ☀️ PV voltage, current, power

• 🔋 DC-link voltage (~400 V maintained)

• 🌐 Grid voltage, current, power

• 🔄 Inverter output voltage (five-level waveform always maintained)

• 🚗 EV battery power and SOC (SOC increases steadily)

• 🏠 Load voltage/current/power

📌 Also, grid current reduces whenever PV power increases, proving correct energy management.

🏁 Conclusion

This MATLAB/Simulink model demonstrates a practical PV-based EV charging station integrated with the grid, using a boost converter with P&O MPPT and a five-level multilevel inverter. The results confirm that the system can intelligently balance power between PV generation, grid supply, EV charging demand, and local household load, ensuring reliable EV charging under all solar conditions.