Research

Pulsed Power

Marx Generators:

Our group leads the frontier in Solid-State Marx Generators (SSMG) and direct-switch pulsed power systems, delivering breakthrough performance where legacy designs fail:

Ultra-fast rise times with precise flat-top control
Inrush current mitigation & perfect stage voltage balancing
Minimal capacitance for compact, high-power-density systems
Arbitrary pulse shaping

Impedance Matching for Pulse Generators:

Impedance matching is a technique to improve the rise time and reduce reflections on a Marx generator during the pulse generation mode of the Marx generator.

Can achieve single digit nanosecond level rise times
Enhances energy delivery efficiency up to approximately 90%, reducing power losses
Maintains pulse rise time independent of the generator’s physical size, allowing scalability without performance degradation

Series Connected Switch System:

Our group is working on advanced gate driver architectures and real-time control algorithms to achieve precise synchronization and robust voltage balancing across series-connected wide-bandgap devices, thereby enhancing the reliability and performance of next-generation HVPPS systems.

Direct-switched High-Voltage Pulsed Power Supplies (HVPPS): Deliver a large DC-link voltage to the load through an Equivalent High Voltage Switch (EHVS).
Equivalent High Voltage Switch (EHVS): Formed by series-connecting multiple SiC MOSFETs or GaN HEMTs.
Number of devices in series: Chosen based on voltage-blocking needs, reliability margins, and derating requirements.
Benefits of EHVS approach: Enables higher voltage and high-frequency operation beyond the capability of a single device.
Critical technical challenges:
First challenge: Uniform static voltage sharing must be ensured when all devices are OFF, as parasitic capacitances and non-linear device capacitances tend to cause uneven voltage distribution.
Second challenge: Precise and synchronous switching is required during turn-on and turn-off transitions to avoid switching delays that lead to transient overvoltage stress and unbalanced dynamic voltage sharing.
Consequences if imbalances are not properly managed: Can result in localized over-stress, device failure, and compromised system reliability.

Direct-Switched High-Voltage pulsed power supply

Dielectric Barrier Discharge (DBD) Power Systems:

DBD Geometry — Various Geometries of DBD Load

Our group researches high-voltage, high-frequency power supplies for efficient and controllable Dielectric Barrier Discharge (DBD) plasma generation. By analyzing non-linear behavior of DBD loads and combining resonant inverters, pulsed power supplies, and advanced HV transformer design, we enable reliable excitation across diverse DBD reactor geometries.

What is DBD?
Non-thermal plasma generated by dielectric-insulated electrodes. Operates at atmospheric pressure and supports applications ranging from food sterilization and chemical conversion to surface treatment and biomedical processing.
Sinusoidal Power Supplies:
Resonant LC/LCL and Class-E inverters provide adjustable HF sinusoidal excitation with soft-switching, high gain, and efficient integration of capacitive DBD loads.
Pulsed Power Supplies (PPS):
Marx generators, pulse-forming networks, and flyback-based pulsers enable nanosecond–microsecond pulses with sharp rise times for enhanced ionization and precise energy delivery.
Waveform & Frequency Control:
Custom waveform shaping—sinusoidal, square, unipolar/bipolar pulses—with frequencies from Hz to MHz allows optimization of plasma uniformity, discharge mode, and application-specific performance.
Reactor Geometry Support:
Designed for VDBD, SDBD, in-package DBD, packed/fluidized-bed DBD, flexible DBD, and floating-electrode configurations, each with distinct impedance and HV requirements.
Key Challenges:
Highly capacitive, threshold-triggered loads; maintaining soft-switching over varying conditions; minimizing transformer parasitics; and ensuring fast, well-shaped HV pulses without ringing.

Our efforts advance next-generation DBD systems by improving plasma stability, energy efficiency, and controllability for industrial and scientific applications.

Modular Multilevel Converters(MMCs)

The Modular Multilevel Converter (MMC) is a widely adopted, scalable topology for medium- and high-voltage applications (HVDC, STATCOMs, drives, pulsed power), thanks to its modularity, near-sinusoidal output waveforms, and built-in redundancy. Its main limitation is large low-frequency (ω, 2ω) ripple in submodule (SM) capacitors, forcing oversized capacitance that increases size, weight, cost, and reduces dynamic performance. Active Power Decoupling MMC (APD-MMC) integrates auxiliary ripple-absorption circuits into each SM, nearly eliminating main-capacitor ripple, enabling 3–10× capacitance reduction, lower circulating currents, higher power density, and cleaner waveforms. However, the resulting multi-loop, time-periodic system demands careful control design to ensure stability and prevent ripple mishandling, voltage drift, duty saturation, or resonances.

T-Type Converters for Solar

Single-phase distributed PV inverters suffer from double-line-frequency (2ω) DC-link voltage ripple due to power mismatch, often requiring bulky, unreliable electrolytic capacitors. The single-phase T-type inverter solves this with low-capacitance film capacitors and integrated active power decoupling (APD) to buffer ripple actively. It also eliminates common-mode leakage current by connecting the PV negative directly to grid neutral. Recent GaN bidirectional devices with higher voltages enable redesign of inductors and switching frequency through loss-vs-volume optimization, delivering 97.8% efficiency at rated power and just 40.4 cm³ inductor volume for a 1 kVA PV string inverter.

Key highlights:

Integrated APD + film capacitors replace electrolytic caps, reducing size/reliability issues while actively managing 2ω ripple
Direct PV-to-neutral connection inherently suppresses leakage current in transformerless designs
GaN-enabled optimization achieves ultra-high efficiency and extreme power density in compact single-phase PV inverters

Hybrid & Renewable Power Source Conversion

Multi-Port Extended-Duty-Ratio Boost Converter

Our group develops high-gain, multi-port power converter architectures to efficiently interface renewable sources, energy storage systems, and DC loads. By extending the capabilities of the Extended-Duty-Ratio (EDR) converter, we create compact, scalable solutions for next-generation hybrid energy systems.

Multi-Port EDR Converter:
Enables multiple input sources (e.g., PV, battery, fuel cell) to be connected to individually controlled phases, allowing independent regulation such as MPPT, battery charge/discharge control, or load management.
High Voltage Gain with Compact Design:
Interleaved inductors and switched-capacitor stages provide significantly higher voltage gain than a conventional boost converter, while distributing device stress and maintaining high efficiency.
Reduced Voltage Stress via Phase-Shift Control:
A modified phase-shift strategy minimizes switch voltage stress across wide duty-ratio ranges, enabling the use of lower-voltage, lower-loss semiconductor devices .
Bidirectional Operation:
Supports energy storage interfaces by replacing diodes with complementary active switches, enabling regulated charge/discharge and flexible power-flow control for hybrid systems.
Applications:
Renewable energy integration, hybrid DC microgrids, PV-battery systems, electrolyzers, EV charging nodes, and high-gain DC distribution.

Our work enables compact, high-efficiency power processing for modern hybrid and renewable energy systems while providing the control flexibility required for diverse source characteristics.