Mastering Electromagnetic Interference (EMI) in Modern Power Electronics Design
In today's electrified world, the importance of electrical power generation and distribution cannot be overstated. With over 70% of electricity processed by various forms of power electronics, the demand for smaller and more efficient designer is rapidly growing. One of the notable trends is the rise of switched-mode power supply (SMPS), driven by wide bandgap semiconductors like silicon carbide (SiC) and gallium nitride (GaN), promising higher power efficiency, increased power density, reduced size, and lower costs.
Figure 1. Wide Bandgap (WBP) semiconductors such SiC and GaN are emerging technologies for power electronics, promising higher switching speeds.
However, these advancements come with higher switching speeds, leading to larger rates of change in voltage and current during phase switching, potentially producing more severe conducted and radiated electromagnetic interference (EMI).
Understanding Electromagnetic Interference (EMI)
EMI refers to the unwanted electromagnetic "noise" that disrupts electronic devices. It can occur either through electromagnetic induction or radiation emitted from an external source. As electronics become smaller, faster, and more tightly packed, they become more susceptible to the disruptive effects of EMI. This is a design challenge that frustrates many power electronics designers since it typically shows up late in the prototype stage.
The sources of EMI can be diverse, encompassing both natural and artificial objects that carry rapidly changing electrical currents. For instance, switch-mode power supplies, characterized by high-speed voltage and current switching, have a propensity for generating substantial radiated and conducted EMI. Addressing both types of EMI requires different approaches and expertise, adding complexity to EMI mitigation. There are strict regulations and standards governing EMI emissions, especially for products intended for consumer use. Ensuring compliance with these standards often requires collaboration among engineers from different disciplines, including electrical, mechanical, and RF engineering.
In light of these challenges, it is no longer sufficient to consider EMI performance after the main power supply design is finished.
Embarking on the Journey into the Heart of EMI
The Power Electronics EMI Curriculum is tailored to educate both students and industry professionals, providing them with the necessary knowledge and skills to effectively address EMI issues.
This educational program centers on a comprehensive approach that promotes hands-on exploration of the fundamentals of EMI within the field of power electronics. The organization of the curriculum has been strategically overseen by Professor Giulia Di Capua from the University of Cassino and Southern Lazio, Italy, and Professor Nicola Femia at the University of Salerno. Their guidance ensures that students systematically comprehend EMI challenges and learn the strategies to overcome them.
How You will Learn
The Power Electronics EMI Laboratory unfolds as a series of well-structured experiments, each delving into specific aspects of EMI within DC-DC power converters.
The experiments enable students to investigate the influence of various elements on EMI, which include:
- power components
- input/output conditions
- control techniques
- PCB layout
By dissecting these elements, students not only understand the roots of EMI issues but also learn how to design and implement solutions.
To facilitate a comprehensive and effective learning experience, students are equipped with essential tools and technologies. The Texas Instruments TI-PMLK BUCK hardware platform, combined with Keysight measurement instruments, such as oscilloscopes, DC power supplies, electronic loads, and current probes, provides students with the means to conduct experiments and gather real-world data. Additionally, the Keysight Advanced Design System (ADS) and PEPro software empowers students to simulate and analyze their experiments before conducting physical measurements.
Each experiment follows a carefully constructed sequence of steps, starting with an introduction to the topic, providing a theoretical foundation, guiding students through hands-on exercises, and concluding with reflections on the results. Moreover, each experiment is enriched with learning resources and answer keys to further enhance the educational experience.
Experiment 1 Basic operation of a DC-DC hysteretic buck regulator
Use the LM3475 Section of the TI-PMLK BUCK hardware platform for experimental measurements and the ADS PMLK-LM3475-Exp1 schematic for simulations. The goal of this experiment is to analyze the operation and the main waveforms of a DC-DC hysteretic buck regulator in terms of switching frequency and relevant harmonics of interest for EMI.
Experiment 2 Impact of power MOSFET on DC-DC buck regulator EMI
With the LM3475 Section of the TI-PMLK BUCK hardware platform for experimental measurements and the ADS PMLK-LM3475-Exp2 schematic for simulations, the engineer will analyze the impact of MOSFET capacitances and resulting switching speed on the EMI of a DC-DC buck regulator.
Experiment 3 Impact of input capacitance de-rating on conducted EMI - hysteretic regulator
By using the LM3475 Section of the TI-PMLK BUCK hardware platform for experimental measurements and the ADS PMLK-LM3475-Exp3 schematic for simulations, the engineer will analyze the impact of input capacitances de-rating and resulting degradation of input filter attenuation on the EMI of a DC-DC buck hysteretic regulator.
Experiment 4 Impact of input capacitance de-rating on conducted EMI - peak-current regulator
The goal of the experiment is to use the TPS54160 Section of the TI-PMLK BUCK hardware platform for experimental measurements and the ADS PMLK-TPS54160-Exp4 schematic for simulations to analyze the impact of input capacitances de-rating and resulting degradation of input filter attenuation on the EMI of a DC-DC buck peak-current regulator.
Experiment 5 Impact of inductor saturation on conducted EMI - hysteretic regulator
With the LM3475 Section of the TI-PMLK BUCK hardware platform for experimental measurements and the ADS PMLK-LM3475-Exp5 schematic for simulations, the engineer will analyze the impact of inductor saturation on the operation and resulting EMI of a DC-DC buck hysteretic regulator.
Experiment 6 Impact of inductor saturation on conducted EMI - peak-current regulator
The experiment will involve the TPS54160 Section of the TI-PMLK BUCK hardware platform for experimental measurements and the ADS PMLK-TPS54160-Exp6 schematic for simulations to analyze the impact of inductor saturation on the operation and resulting EMI of a DC-DC buck peak-current regulator.
Experiment 7 Impact of the peak-current control instability on EMI
The experiment requires the TPS54160 Section of the TI-PMLK BUCK hardware platform for experimental measurements and the ADS PMLK-TPS54160-Exp7 schematic for simulations to analyze the operation, the main waveforms, the subharmonic operation, and the instability of a DC-DC peak-current controlled buck regulator and resulting effects on EMI.
Experiment 8 Impact of PCB layout capacitances on EMI
The experiment requires the TPS54160 Section of the TI-PMLK BUCK hardware platform for experimental measurements and the ADS PMLK-TPS54160-Exp8 schematic for simulations to analyze the impact of PCB parasitic capacitances between the power train and the control circuitry on the operation of a DC-DC buck peak-current regulator and resulting EMI effects
What You Will Learn
We believe mastering EMI in power electronics requires a blend of theoretical understanding and practical expertise. The Power Electronics EMI Laboratory serves as your gateway to both worlds with five key learning objectives.
Simulate DC-DC buck regulators
By working with specified power components, control setups, and operating conditions, students will have the ability to simulate these regulators in steady-state operation. They can then analyze and interpret the key waveforms associated with conducted EMI.
Identify noise sources
Students will learn to identify the main power components generating the EMI and make changes to optimize their characteristics, ultimately improving EMI performance.
Analyze control parameters
The curriculum equips students with the knowledge to understand how various control parameters impact EMI. They will have the ability to modify the circuit setup to enhance EMI performance.
Understand PCB layout's impact
You will grasp the significance of PCB parasitic parameters and their influence on noise generation and propagation. They will learn to make critical changes to the PCB layout to improve EMI performance.
Explore the holistic view
By working with specific topologies, power components, control setups, and functional schematics, you will discern the factors contributing to noise generation, propagation, magnification, and mixing in power electronics. They can make informed changes to optimize performance, validating their improvements through thorough time-domain and frequency-domain analyses.
Conclusion
We are excited to introduce the Power Electronics EMI Laboratory as am practical educational resource and grateful for the collaboration with Professor Giulia Di Capua and Professor Nicola Femia. At Keysight, we believe that EMI is not merely a hurdle; it may hold the key to innovations in electrical engineering, materials science, and signal processing. As we continue to explore these opportunities, we look forward to collaborating with aspiring design engineers on unlocking the full potential of EMI in the ever-evolving world of power electronics.
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