Interview with Dr. Ali Bazzi

Featured Engineer

Dr. Ali Bazzi

Dr. Ali Bazzi - Senior Power Electronics Electrical Engineer, Delphi Electronics & Safety

How did you get into electronics/ engineering and when did you start?

I have always been interested in “engineering.” While I was growing up, I was one of those kids that disassembled my remote control cars and other toys; tried to wire motors, switches, small light bulbs and batteries; and imagined circuit boards were green areas with structures and roads. My interest in electronics started in high school physics classes when we studied electricity, and my interest in computers began in 1986 when my parents bought a basic computer that was hooked to a TV screen.

When I reached college, I was accepted in an excellent electrical engineering program, and it was my first power electronics course in 2004 that exposed me to different power electronics systems and sparked my interest in the field. By the senior year of my undergraduate studies, I was focused on power electronics, electric drives, electric machines and power systems, and power electronics became the subject of my master’s and doctoral research and studies.

What are your favorite hardware tools that you use?

Among my favorite tools are power analyzers that can monitor multi-phase electrical quantities in several applications such as motor drives and grid-connected renewable energy systems. They perform interesting calculations of power, power factor and other quantities, and can provide very valuable information in power electronics systems development.

Also, I am really interested in DSP and FPGA boards that use graphical programming. Control and sensing are major requirements when working with power electronics,. Several manufacturers currently supply boards that can be simply programmed with block diagrams built into compatible software. While the code generated by these graphical interfaces might not be fully optimized, visual block diagrams and time savings are very attractive because the goal is to have functional power electronics systems rather than just individual blocks.

What are your favorite software tools that you use?

My favorite software tools are MATLAB and Simulink. I have used both of these tools for several years – sometimes on daily basis. MATLAB provides essential mathematical tools and simple programming capabilities. Simulink is the part of the MATLAB package that performs block diagram simulations. With several useful tool boxes, including the SimPowerSystems and the Simulink Real-Time Workshop, it can interface with DSPs and FPGAs by compiling block diagrams into files used by other software to program hardware, such as Code Composer Studio software to program DSPs.

What is a recent “bug” you have fixed?

I was recently measuring a low-voltage signal that feeds into a gate drive chip of an inverter. The signal had glitches on the oscilloscope even though the inverter was running fine and there were no performance issues. This confused me for a couple of hours, but I kept tracing the signal and seeing different glitches. I finally realized that the differential probe I was using was capturing noise on top of the actual signal because one of the circuit grounds was floating. When I appropriately tied the ground layer of the board to the supply ground, noise was eliminated, and all measurements looked better.

What is on your bookshelf?

I mainly have books related to power electronics, electric machines and drives, and control systems. I also have several books on power systems and renewable energy resources in addition to several theses and technical reports that are related to these fields, mainly from the Power and Energy Group at the University of Illinois at Urbana-Champaign where I received my PhD.

Do you have any tricks up your sleeve

Two very important ones — I try to keep things simple as long as it does not impact performance, and I try to find a way to run any system in open-loop mode first. This means that I eliminate any information fed back to the controller and run some diagnostic steps. Such a procedure helps isolate problems resulting from control and sensing from power electronics. It can also show some performance measures such as ability to handle a certain voltage, current, power and temperature rise.

What has been your favorite project?

I find that all projects are very interesting to me, in one way or another. What first comes to mind is a project that became a building block for several research topics — a battery-charging solar photovoltaic system that was later used for testing different real-time optimization algorithms, system reliability and system efficiency. Several people helped with this project and many others are still using it as the basis for research.

The challenging performance constraints of the automotive inverter project on which I am currently working have made it especially interesting. It definitely requires several experts to work together, and so far, I have not only been able to share my expertise, but I have also learned a great deal.

Do you have any noteworthy engineering experiences?

In power electronics, it is very common to blow up things in the lab, so this doesn’t count.

I always remember that I built my first power electronics circuit, a single-phase inverter, without any previous hands-on experience in power electronics design. I had had very limited lab mentoring and had to experiment and read a lot. Learning some of the basics from scratch – PCB design, inductor design, gate drive circuit design, and thermal management of semiconductors, my experience wasn’t a “smooth ride,” and as I recall, the lab fire alarm went off at least once.

One noteworthy accomplishment is the core of my PhD dissertation – combining efficiency and reliability enhancement in induction motor drives. The integration of motor drives in a wide spectrum of applications, including transportation, requires reliability enhancement and benefits significantly from energy savings.

What are you currently working on?

I am currently part of a team that is designing several automotive inverters and integrating them in one package. We are at a stage where final tweaks and tests are being performed to ensure that we meet all specifications. This project is both an electrical and mechanical challenge, especially when you consider automotive requirements and thermal management.

What direction do you see power electronics heading in the next few years?

I believe that the power electronics field is ripe for expansion, especially with the global push for a cleaner environment and more efficient energy consumption. Expansion will be in several areas: 1) new semiconductor devices as we’ve seen with SiC and are seeing with GaN semiconductors, 2) magnetic components with size and performance improvement, 3) overall system efficiency improvement to reduce losses and thermal stresses, and 4) more complex systems on a chip. I also expect power electronics to become important outside of the automotive market – in household appliances; transportation, including aircraft; and, renewable energy applications with power ranging from μW or mW in energy harvesting applications to GW in large-scale wind and solar farms.

What challenges do you foresee in the power electronics industry?

I believe that one of the major challenges of the industry is to increase system efficiency. To do this we need to increase the efficiency of components while reducing losses and saving energy. As power densities and requirements of power electronics systems increase, thermal management becomes a major challenge. And, as new components are introduced, they are being expected to be more efficient while having superior thermal characteristics. Making sure that power electronics have all of these characteristics will be a challenge as we move into the future.

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