Abstract — Modular Multilevel Converter
Modular multilevel converters (MMCs), as one of the core components of hybrid AC/DC power grids, become the preferred converter topology and show good developments. Urgently, a general MMC modeling scheme with good model accuracy needs to be developed to realize small-signal analyses and designs for the large-scale AC/DC power grids easily. This paper proposes a unified modeling scheme (UMS) for MMC systems in a synchronous rotating ( dq ) reference frame. Based on the dynamic phasor theory and with the proposed modular decouple modeling (MDM), the nonlinear state-space model of the overall MMC system can be obtained by configuring and connecting the input and output of the state-space model of each subsystem. Besides, the unified controller, modeling different control modes, normalizes the MMC systems modeling.
Analytical & State-Space Control Methodology
Simultaneously, with the proposal of UMS, linearization and splicing could be uesd to develop a small-signal model of the overall MMC system directly. Therefore, the proposed model is suitable for simulating the large-scale hybrid AC/DC power grids and analyzing the stability of small-signal. Finally, the simulation results verify the accuracy and effectiveness of the proposed modeling method.
Simulink Waveforms & Power Quality Findings
Figure 1: Power Converter Circuit Schematic & Electrical Interfacing for Modular Multilevel Converter A large number of distributed energy resources (DERs), from transmission systems to distribution networks, have been grid connection and consumption of large-scale renewable energy. In particular, high-voltage direct current (HVDC) transmission technology has good application prospects in the field of renewable consumption and long-distance transmission ( Liu et al., 2014 ; Zhu et al., 2021 ; Zhao and Tao, 2021 ); In addition, with the development of urbanization and the rapid growth of DC load, DC distribution network has attracted extensive attentions from scholars and the industry because of its flexible control ( Sun et al., 2021 ; Xianyong et al., 2021 ). Modular multilevel converters (MMCs) become the preferred topology of high power converters for flexible AC/DC power grids, showing good development prospects ( Trinh et al., 2016 ; Wang et al., 2021 ). Therefore, a model reflecting the general operating rules of MMC systems can provide essential guidance in studying the operation characteristics of hybrid AC/DC power grids, selecting the operational parameters of circuits, designing the controllers, and analyzing the stability of AC/DC power grids.
Scope & Practical Applications
- High-efficiency DC-DC converters and isolated resonant topologies (LLC / DAB)
- Sinusoidal and Space Vector PWM inverters for grid integration & industrial motor drives
- MOSFET / IGBT gate driver optimization with active Miller-clamp shoot-through protection
- Power quality conditioning with Total Harmonic Distortion (THD) strictly compliant with IEEE 519
- Complete Simscape .SLX model files, parameter calculation scripts, and IEEE dissertation reports
Simscape Modeling
Simulink power stage & discrete PWM solver
Semiconductor Loss
SiC MOSFET & IGBT thermal dissipation
SVPWM Control
Vector control, FOC & digital PI loops
IEEE 519 Quality
FFT harmonic spectrum & THD < 5% verification
Gate Driver Protection
Isolated bootstrap & Miller clamp circuits
HIL Prototyping
Ready for dSPACE, OPAL-RT & TI C2000 DSP
Engineering Software & Simulation Toolchains
Modeled using industry-standard power electronics simulation platforms, discrete numerical solvers, and HIL testbeds.
| Software Platform | Analytical Function & Role | Simulation Tier |
|---|---|---|
| MATLAB R2024b | Small-signal state-space averaging, bode stability margins, LC filter design, FFT analysis | Analytical Core |
| Simulink / Simscape | Time-domain switching models, non-linear semiconductor models, discrete PI controllers | System Simulator |
| PLECS / PSIM | High-speed thermal loss estimation (conduction and switching Eon/Eoff), snubber design | Thermal & Losses |
| Altium Designer | High-voltage isolation layout, creepage/clearance, power loop parasitic inductance minimization | Hardware PCB |
| TI C2000 / dSPACE | Embedded C codegen from Simulink, high-resolution ePWM registers, Hardware-in-the-Loop test | HIL Deployment |
Power Conversion & Control Topology Workflow
Systematic integration from DC input energy source and high-frequency gate drive to digital control loops and load delivery.
Renewable Bus
MOSFET/IGBT Bridge
& SVPWM Loop
Filter Stage
& FFT Analyzer
Motor Load
Verified Simulink Block Diagrams & Converter Waveforms
Advantages of the Modular Multilevel Converter Project
Why this project delivers superior academic grades and provides high technical evaluation standing.
High-Fidelity Simscape Modeling
Provides precise numerical simulation of switching events using ODE variable-step solvers without numerical divergence.
Rigorous IEEE 519 Grid Compliance
Guarantees total harmonic distortion (THD) below 5% through optimized LCL filter attenuation and synchronous control loops.
Wide-Bandgap Semiconductor Sizing
Models modern SiC MOSFETs and GaN switches to achieve power conversion efficiencies exceeding 97.5% across full-load regimes.
Advanced Digital Modulation
Implements Space Vector PWM (SVPWM) and sinusoidal modulation maximizing DC-bus utilization by 15.5% over carrier methods.
Dynamic Small-Signal Stability
Custom MATLAB scripts compute control-to-output transfer functions Gvd(s), phase margins (> 50°), and gain margins.
Gate Driver Protection Mechanics
Incorporates active Miller clamps, negative turn-off bias, and isolated bootstrap circuitry to eliminate shoot-through faults.
Hardware-in-the-Loop (HIL) Ready
Directly exportable to embedded C for execution on Texas Instruments C2000 DSPs, dSPACE, and OPAL-RT real-time platforms.
Detailed Magnetic Core Sizing
Features rigorous inductor and high-frequency transformer calculations ensuring core saturation flux margins remain safe.
Direct Electric Vehicle & Grid Value
Builds technical competencies demanded by top automotive EV powertrain developers, solar EPCs, and power electronics consultancies.
Complete Turnkey Package
Delivered with full Simulink .SLX models, MATLAB initialization scripts, calculation sheets, IEEE-format report, and viva defense slides.
Sample MATLAB Code, Scope Waveforms & Harmonic Schedules
Representative excerpts illustrating the state-space analytical derivations, command solver output, and power quality distortion schedules.
[*] Compiling Simscape Electrical Switching Topology Engine... [✓] SiC MOSFET / GaN Switching Semiconductor Characteristics Loaded ──────────────────────────────────────────────────────────────────────── [OUTPUT REGULATION] Steady-State DC Voltage: 24.01 V (Ripple: 0.18 V p-p) [TRANSIENT STEP] 50% to 100% Load Recovery: 0.82 ms (Overshoot: < 1.4%) [SEMICONDUCTOR] Total Switching Loss (Psw): Psw = 4.82 W at 100 kHz [CONVERSION η] Full-Load Power Efficiency: η = 97.42% (Optimal Operating Band) ──────────────────────────────────────────────────────────────────────── [✓] Small-Signal Compensator Verified: Phase Margin = 54.8° (Robust Loop Stability)
[*] Simulating converter steady-state operating envelope across switching cycles...
| Electrical Parameter | Design Objective | Simulink Simulated Metric | Performance Variance | Status |
|---|---|---|---|---|
| Regulated Output Voltage | 24.00 V | 24.01 V | +0.04% | REGULATED |
| Inductor Current Ripple | < 25.0% | 18.4% | -26.4% | OPTIMAL |
| Voltage Peak Ripple | < 240 mV | 180 mV | -25.0% | OPTIMAL |
| Power Conversion Efficiency | > 95.0% | 97.42% | +2.42% | HIGH EFFICIENCY |
[✓] Power Quality Verification Complete: Injected harmonic components conform strictly to IEEE 519 standards.
Frequently Asked Questions
Project Deliverables & Support
Everything needed from project inception to final viva defense — delivered with expert technical support.
.SLX Files
.M Files
Schematics
Report
Slides
Recordings
Sheets
Q&A
Support
Extension