Today we are taking a short dive into some of the technical details of the unique TorqIQ™ technology behind Bowman’s eTurbo Systems, with Advanced Engineering Director, Shinri Szymko. Read on to learn about the challenges that need to be overcome, how Bowman combines expertise in many disciplines to rise to these challenges… and some amazing statistics about the phenomena involved!

Technology and material science continually advance, and it was the advent of rare-earth magnet materials, together with developments in the field of power electronics, that enabled new possibilities in direct ‘on-shaft’ electrification of turbomachinery products. Bowman has been there since the beginning, constantly refining its own unique TorqIQ™ technology.

Broad challenges demand a range of disciplines

The technical challenges in doing this stem from the high speed and power densities of the turbomachinery. Compressor and turbine blade tips approach the speed of sound and rotational speeds are measured in the 10’s and 100’s of thousands of revolutions per minute. Temperatures in engine exhaust gas streams can approach 1000 degrees C. The electrical machines and power electronics therefore need to match these challenging characteristics and be viable in the harsh operating environments. This requires a broad range of technologies to come together in harmony to make products viable.

Surprisingly large forces and speeds being controlled

Maximising performance of the turbomachinery through electrification requires pushing many of the different engineering disciplines close to their limits – a ‘balancing act’ is needed to provide the optimum blend of performance, reliability, and cost. For the electrical machine, the tension is between the rotor-dynamics, electromagnetics, thermal characteristics, and mechanical stresses. The very high rotational speeds mean that the electrical machines can be volumetrically many times smaller than the low-speed equivalent, therefore these machines must be incredibly efficient so that the heat generated through losses can be removed from the small surface areas. Again, due to the high speed of operation, it may surprise people to learn that a single magnet on the rotor shaft can require a force equivalent to the weight of six African elephants to hold it in place… and there are six of these in a space smaller than a shoebox!

The high speed of rotation also means that the fundamental frequency of these machines is often measured in kHz rather than simply Hz. For instance, a 2-pole, 120,000 rpm machine will have a fundamental frequency of 2 kHz compared to a 4-pole 50 Hz mains frequency machine (typical of normal motors in everyday uses). This means that the control of the current waveforms used to drive the motor/generator must occur at phenomenally high speed, which, in turn, means that switching losses within the power transistors need to be understood and optimised. There are many other high-speed effects that need to be considered as a system, such as the rate of voltage rise in the machine and the capacitive leakage current of the machine. To optimise the system as a whole requires state of the art technology and understanding.

Software and power electronics are key

Moving onto software, the control of electrified turbomachinery at such high speeds requires careful consideration of the algorithms – ensuring that control is maintained whilst also managing the quality of electrical current waveforms that are fed to the electrical machine. This is particularly important so that the current does not generate excessive harmonic losses in the rotor of the electrical machine. Similarly, accelerating a machine from 0 to 50,000 rpm in <0.3 seconds requires accurate dynamic control of the rotor and special attention to positional accuracy.

Because of the heavy interactions between the electrical machine, power electronics, and software controls, it is important to develop these in consideration of each other, and Bowman has brought the broad range of disciplines together in order to achieve this with its TorqIQ™ technology.

Bowman's knowledge and patents

Moving beyond the eTurbo Systems products themselves, it is important that we develop and retain a strong understanding of the engines and fuel cells on which they will be used. Bowman has a strong background working with engine OEMs (Original Equipment Manufacturers) on their various products and turbomachinery operation, and has developed sophisticated analysis tools and databases of information to quickly allow the value of different applications to be understood.

The complexity and the time required to be successful in developing high-speed machine systems mean it is important to protect this learning. Bowman has a number of patent families granted, with several more in application, and importantly our team has experiential intellectual property relating to the processes and design data necessary to be successful.

Deep service experience in key markets

The need for turbomachinery electrification is driven by environmental legislation, increasingly imperative for climate change mitigation, and the raw economics of the cost of operation. As we’ve covered in other articles, eTurbo Systems provide a completely new degree of freedom to the design of combustion engines, enabling them to be more efficient in the use of today’s fuels and accelerate the transition to future clean (net zero) fuels. Bowman has been focused on maturing its TorqIQ™ technology to meet these fundamental requirements over the last two decades in industrial, locomotive, and automotive sectors. The development of eTurbines, eTurbochargers, eCompressors and their associated power electronics and software controls provides trucks, tractors, locomotives and industrial gensets numerous benefits.

As well as a broad range of expert capabilities in different engineering disciplines, successfully and reliably electrifying turbomachinery requires deep service experience. Bowman has amassed nearly 30 million running hours in the field and has been developing its expert team and design data over the last 20 years.

Looking to – and providing power for – the future

Having deployed over 1,000 industrial units into the field, on diesel and gas gensets in a range of applications, Bowman’s experience has been an invaluable platform to understand the complexities of operation with our customers, and provide the long-term operation and subsequent statistics required to flush out design and operational issues. As this remains an emerging technology, there is a learning experience for our customers as well as ourselves. Bowman has developed over three generations of electrified turbomachinery, and five generations of power electronics, and have fed learnings back to optimise all of these. We continue to look to the future in our TorqIQ™ technology application to ensure the products are fit for the years to come, providing the intelligence and reliability necessary for these applications.

Whether it be to enable traditional diesel and gas gensets to operate more intelligently, or to support hydrogen-fuelled internal combustion engines or fuel cells where minimisation of the parasitic losses is critical for success – Bowman’s eTurbo Systems, powered by our TorqIQ™ technology, will enable dependable, ever cleaner, and sustainable provision of power for generations to come, positively contributing to a net zero future.