Abstract — Resonant LLC Converter
Resonant Llc Converter: Power Electronics, MATLAB/Simulink & Circuit Modeling Integrated Analysis: MATLAB/Simulink · MOSFET/IGBT Gate Drivers · SPWM/SVPWM · THD Spectrum · ~5656 Words Chapter 1: Power Electronics Overview, System Specifications & Topology Modeling This technical note provides an introduction to the LLC converter, which is an isolated DC-DC converter, popular in a multitude of fields. It is the first in a family of articles discussing the LLC converter: The fundamental harmonic approximation is presented as a modeling technique before the operation of the LLC converter is discussed above resonance, at resonance, and below resonance.
Analytical & State-Space Control Methodology
Following that, this technical note demonstrates how to build and operate an LLC converter using imperix hardware and software, and compares the physical implementation with the theory and the simulated plant. Figure 1: Power Converter Circuit Schematic & Electrical Interfacing for Resonant Llc Converter Most applications of LLC converters are characterized by the use of a resonant tank to induce a lag between the current and the voltage while exciting its isolation transformer with a near-sinusoidal current. This lagging current allows the LLC converter to operate in Zero Voltage Switching (ZVS) mode, while the sinusoidal current allows the isolation transformer to operate efficiently. On the secondary side of the transformer, rectification of the voltage can be done using diodes, or using synchronous rectifiers. This rectification occurs in Zero Current Switching (ZCS) mode. The resulting high efficiency allows the designer to increase the frequency of the LLC converter, reducing the size of all passives.
Simulink Waveforms & Power Quality Findings
Figure 1 is a schematic of a full-bridge LLC converter. The switches on the secondary of the transformer are present to perform rectification. In a unidirectional application such as in this technical note, they can also be replaced with diodes. Multiple modulation schemes exist for controlling LLC converters . The modulation strategy considered in this technical note is Pulse Frequency Modulation (PFM). PFM changes the frequency of voltage \(V_1\), which changes the magnitude of current \(I_{Lr}\). The change of the current in the resonant tank affects voltages \(V_2\) and \(V_{load}\).
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 Resonant LLC 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