The next generation of electric motors
The motor control methods developed by Asad Awan make the new kind of electric motor a serious contender to the cage induction motors dominating the market today.
– Nearly half of the electricity produced in the EU is spent in electric motors, says Asad Awan from ABB to introduce his dissertation.
Even a slight increase in efficiency would therefore mean significant savings in energy consumption. The most promising competitor to the traditional cage induction motor is the synchronous reluctance motor.
The most promising competitor to the traditional cage induction motor is the synchronous reluctance motor.
– It is smaller in size and induces less dissipation than cage induction motors, says Awan.
In light of this, it is no wonder that the selectors of the 2020 doctoral thesis award at Academic Engineers and Architects in Finland TEK and TFiF Tekniska föreningen i Finland chose to highlight Awan’s dissertation as the best from a group of 30 high-quality candidates.
”The reluctance motor Awan discusses in his dissertation would be a terrific option for industry as its manufacturing costs are competitive with cage induction motors, it results in significantly smaller energy losses than cage induction motors and its manufacturing does not require rare earth metals”, said the jury in justification of their choice.
An old invention that is difficult to adjust
As an invention, the new kind of motor is not that new: the principle was first presented in 1923. However, we had to wait nearly 90 years for the first commercial application. ABB introduced its first synchronous reluctance motor in 2012.
The explanation for the long road to commercialisation is simple.
The synchronous reluctance motor does not turn on automatically when connected to alternating current. It requires the help of a frequency converter that allows the user to adjust the current fed into the motor and its frequency. This technology was only first utilised in the Helsinki Metro in the 1980s.
Since then the frequency converter technology has rapidly become more common in controlling cage induction motors.
Synchronous reluctance motors, however, require a special control method of their own.
– Adjusting the motor is extremely difficult, Asad Awan says.
These control methods are exactly what Awan discusses in his dissertation.
For industrial use and electric cars
The benefits of synchronous motors are indisputable. In industrial use their most significant benefit is the improved efficiency when compared to cage induction motors.
In pump and conveyor motors that run 24/7, an improvement of a couple of percentage points could mean annual savings of hundreds or thousands of euros. Car manufacturers are also attracted by the motor’s small size, good torsion at low RPM and the possibility for high rotation speeds.
The features of the motor can be customised by adding permanent magnets. For example, the electric car manufacturer Tesla replaced their cage induction motors with permanent-magnet synchronous motors in their latest Model 3s.
However, there are some obstacles to their popularisation.
For the synchronous reluctance motors to become more mainstream, they should be able to function without speed and motion sensors like the current cage induction motors do. It should also be possible to freely mix and match frequency converters and motors from different manufacturers.
The software controlling the motor should also be able to automatically recognise the features of the motor connected to it and adjust itself automatically to suit the motor.
This is exactly what Asad Awan’s dissertation tackles. At the core of the work is a piece of software that enables the control of different synchronous reluctance and permanent magnet motors.
– This is the perfect package. It recognises the features of the motor and controls it effectively, Awan says.
This is the perfect package. It recognises the features of the motor and controls it effectively.
The methods discussed in the dissertation are useful in both industrial uses and vehicle motors.
Of the six research papers that the doctoral thesis consists of, Awan’s personal favourite is the one on the plug-and-play method he developed to start synchronous motors. IEEE Industry Applications Society chose that paper as the best research article of 2018 on electric motor drives.
– You only need the basic information about the motor, its operating voltage and output.
With this information, Awan’s algorithm recognises the magnetic properties of the motor connected to the frequency converter and says how it needs to be adjusted.
As they are, the methods would be suitable for controlling the motors of the new Model 3 Tesla, for example.
The first two research papers of Awan’s thesis present a new kind of mathematical model for adjusting the current of synchronous reluctance motors. It is especially useful in high-speed vehicle motors.
The adjustment algorithm runs without sensors and calculates the electromagnetic state of the motor and the position of its rotor in real time. Based on this information, the frequency converter controlling the motor adjusts the current up to thousands of times per second to maintain the speed of rotation and moment at exactly the desired levels.
Awan completed his dissertation in a research group on electric drives headed by Professor Marko Hinkkanen. The real-time adjustment of power electronics and mathematical estimation are the group’s top strengths.
Developments in power electronics have allowed the new motor type to enter the market. The challenge faced by researchers is how to control it as intelligently as possible.
One must be very familiar with the physics. Everything is based on physical models of the controlled motor.
– One must be very familiar with the physics. Everything is based on physical models of the controlled motor, says Professor Hinkkanen, who supervised Awan’s work.
Asad Awan joined Hinkkanen’s group for a summer job in 2014. After joining the group, both Awan’s master’s thesis and doctoral dissertation were completed at a rapid pace. In the fall of 2019, the freshly minted doctor transferred to the payroll of ABB who were funding the group’s research.
– Asad Awan was really hard-working and motivated – and quick to learn. His dissertation was easy to supervise, Hinkkanen recalls.
The Professor is not sad to see the award-winning thesis author moving from academia to industry.
– That is our goal, he states.
Synchronous motors are coming
Nikola Tesla (1856–1943) developed a cage induction motor that ran on alternating current in the 1880s and its central principles remain in use even in today’s electric motors.
Currently, over 90 % of electric motors used in industry are traditional cage induction motors. They are reliable and affordable.
However, new and more efficient electric motors are now beginning to seize ground. There are several new motor types, but they all share a single characteristic. They are all so-called synchronous motors. The name stems from how the motor’s rotor is locked to spin synchronously with the stator’s magnetic field. By contrast, a cage induction motor is an asynchronous motor. When under stress, its rotor spins slower than the stator’s magnetic field, which means there is a little slip.
Aalto University Professor Marko Hinkkanen says the synchronous motor is more difficult than its predecessor from a control engineering standpoint. Adjusting its drive in an energy-efficient manner is significantly more difficult than adjusting a cage induction motor.
– Adjusting a synchronous motor involves many factors. Asad Awan’s dissertation work focused on developing methods for doing exactly that.
Asad Awan’s road to his doctorate
1990. Asad Awan is born in the town of Mandi Bahauddin in northern Pakistan.
2004. Because of his interest in physics, Awan decides to apply for engineering studies.
2008. Awan begins electrical engineering studies at the Lahore University of Engineering and Technology (UET).
2012. Graduates as a Bachelor of Engineering from UET.
2013. Awan begins master’s studies at the School of Electrical Engineering at Aalto University.
– One of my teachers had conducted their dissertation research together with a professor from Aalto University.
2014. Summer job in Marko Hinkkanen’s research group continues first in the form of a master’s thesis and then in the form of a doctoral thesis.
2015. Asad Awan graduates as a Master of Science in Technology and begins post-graduate studies.
2019. Doctoral thesis titled ”Control methods for Permanent-Magnet Synchronous Reluctance Motor Drives” is accepted, Awan begins work at ABB.
2020. Awan receives the 2020 doctoral thesis award from TEK and TFiF.
What would you like to accomplish as a Doctor of Engineering?
– It would be great if the vehicular industry also adopted the methods presented in my dissertation.
What is your favourite toy?
– The Canon 77D systems camera.
What is your favourite hobby?
– Playing card and board games with my friends. I just don’t have much time for that now that we have a one-year-old daughter in the family.
ABB employs doctors from Aalto University
Asad Awan answers the Teams call from ABB’s offices in Pitäjämäki. In the time of corona, half of the product development engineer’s work week is spent at his home office in Espoo and the other half at the workplace. He is currently working on new motor control software. Awan promises that results of his dissertation work will begin to appear in ABB’s products in the near future.
Many of his colleagues are also doctors of engineering. In addition to Aalto and other Finnish universities, ABB has attracted electric motor experts from all over Europe. The motor control development for ABB’s synchronous motor products is mainly conducted in Finland.
Initially, Awan’s research ideas will end up in general industrial motors. The recently graduated doctor hopes that in the future they could also be utilised in heavy machinery and high-speed vehicle motors, for example. Their benefits would be even greater in the more challenging applications.
The global company can offer employment all over the world. However, Asad Awan has lived in Finland for seven years and feels well at home.
– I have no plans to move anywhere else. It is so peaceful here, says the former resident of Lahore (population: 11 million) with a laugh.
In addition to the acceptance of his dissertation, last year brought another joyous occasion to Awan: a daughter was born into his family.