Projects

Development of a 3-in-1 reversible hybrid engine that can be operated as an autonomous combustion engine (gaseous, especially hydrogen), electric motor and generator. The core of the research lies in the development of a helical rotary unit that can provide functionality as a combustion electric motor and generator. A simple construction of a movable cylindrical helicoidal piston between two immovable cylinder heads allows irreversible rotating and thus effective operation. A crankshaft and valveless design with only five main components ensures a lower engine mass and high power density. Thanks to the cylindrical shape of all mechanical parts, the engine can be developed as an electric motor and generator. The electrical part can be implemented directly in the construction or docked from the outside. The design allows scalability of the motor, which means that different power spectra can be covered.
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Vertical axis turbines are an area-efficient technology for the sustainable use of tidal currents. However, the vertical axis of rotation causes a dynamic stall, which reduces the efficiency of the turbines and, in the worst case, can lead to material failure due to fatigue fractures. Drives integrated into the blades should ensure that the turbine blades adapt optimally to the flow during each rotation by pitching the blade. Dynamic stall can thus be prevented. This leads to higher efficiency with lower structural loads and the self-starting behavior of the turbine can be improved. Experimental hardware-based optimization methods are combined with numerical methods to determine an optimized control of the pitch function.
The project is an international cooperation between the Institute of Fluid Mechanics and Thermodynamics and the Institute of Electrical Energy Systems at Otto von Guericke University Magdeburg, the Institute of Mechanical Engineering at Magdeburg-Stendal University of Applied Sciences and the Laboratoire des Écoulements Géophysiques et Industriels at the Université Grenoble-Alpes.
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The aim of the project is to develop a permanently excited synchronous motor for small drives (in the range of 10 W to 1 kW) in a very simple design in order to reduce the manufacturing costs compared to conventional motors. It is expected that the production time and steps will be reduced by approx. 30 %. At the same time, the efficiency and power density should be comparable to or even exceed the state of the art. The solution method is based on a special motor design with three plug-in coils and a new type of injection-moulded rotor based on a magnetic composite material (e.g. isotropic neodymium), which is partially or fully magnetized by an external magnetic field during the injection process. In contrast to previous approaches with similar coil designs, only a low cogging torque of approx. 2 % remains here. The new motor design therefore allows a flexible and cost-effective production process and is of great interest to a wide range of users of compact electric motors, for example in medical technology or the automotive industry.
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In the assessment of hydropower plants (HPPs), previously caught wild fish are fed into the power plant turbines and the mortality and number and severity of injuries are determined after the fish have descended.
In Germany, > 460,000 test animals have been used in the past three years to study fish downstream of wind turbines.

The aim of the research project is to reduce fish experiments to evaluate the damage to fish during the passage of turbines and other downstream corridors at power plants and to supplement them with models for damage prediction using data from semi-autonomous robotic systems and numerical simulations and, in the long term, to replace them completely.
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In the assessment of hydropower plants (HPPs), previously caught wild fish are fed into the power plant turbines and the mortality and number and severity of injuries are determined after the fish have descended.
In Germany, > 460,000 test animals have been used in the past three years to study fish downstream of wind turbines.

The aim of the research project is to reduce fish experiments to evaluate the damage to fish during the passage of turbines and other downstream corridors at power plants and to supplement them with models for damage prediction using data from semi-autonomous robotic systems and numerical simulations and, in the long term, to replace them completely.
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The proposed project is part of the development of electric gearless direct drives for mechanical engineering applications. The aim is to develop a directly driven ring segment generator for high torques and low speeds as an energy converter on a folding blade waterwheel.

A special feature of this machine design is the two-phase design, which results from the double-sided use of the rotor disk and with which a high degree of efficiency can be achieved at very low speeds. This generator design is particularly suitable as a modular and highly efficient direct-drive energy converter for hydropower plants. There are currently no standard machines available on the market for this area of application.
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The efficiency of the energy conversion from the battery to the motor is particularly relevant in order to make optimum use of the limited energy reserves in the electric vehicle and thus increase the range. In order to realize the holistic approach, the project is working on improvements in three areas: Energy storage, the motor and the interaction of all electrical components. By storing the braking energy that repeatedly occurs for short periods in a supercapacitor, instead of in the lithium battery as was previously the case, power losses are avoided and the number of charging cycles is reduced. In addition, the voltage converter and electric motor are optimally matched to each other using innovative control processes in order to minimize further energy losses. The aforementioned electronic components are integrated using new measurement and simulation processes in order to minimize mutual interference and disturbance variables during operation.
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In a cooperation between the Chair of "Electrical Machines" and the Chair of "Energy Conversion Systems for Mobile Applications", a direct-drive free-piston motor has been developed. The special feature here is that the 4 strokes are not generated with a rotary movement of the crankshaft but with a linear movement of a rod that is directly connected to a piston. This movement is possible because a linear electric machine works as a motor in three cycles and as a generator in one cycle. The detachment from the crankshaft results in a new degree of freedom in the control of combustion engines. This trainer is therefore used to investigate the influence of the piston stroke on the combustion process.
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Failures in wind power generators are responsible for high reparation costs and loss of availability. In
addition, it is very difficult to perform periodic inspection and maintenance in these plants. Therefore, methods for the early detection and diagnostic of failures, which can be implemented on-line and without intervention of personnel are investigated in this project. Methods based on signal injection have high potential to perform this task.
The objective of this project is to investigate the failure diagnosis and the signal injection together as a
unified function with integrated methods. The complementary experience of both groups and their similar research fields will provide an additional scientific value for the cooperation. This will lead to the
development of new on-line methods for the detection and diagnosis of incipient failures in wind power
generators.
The non-invasive implementation of these methods is an additional objective of this project. This mean, it will be researched how to detect and make a diagnosis of failures without a direct electrical contact to the generator and without modifying or perturbing the control system.

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The objectives when designing electric drives are high torque density, reliability and efficiency, low costs and good motion control properties. In most cases, the research and development of electric drives is divided into two parts. On the one hand there is the design of the electrical machine and on the other the control and power electronics.

The usual approaches to the control of electrical machines are based on a standard machine. The machine, in turn, is designed for a standard control method. The design of the electrical machine and the design of the control algorithm are usually carried out by independent working groups.
In the case of permanently excited synchronous machines (PSM), the machine is usually designed in such a way that a sinusoidal electromotive force (EMF) is obtained. It is assumed that the controller supplies the machine with a sinusoidal current. The controller on the other side is designed for a sinusoidal current, as it is assumed that the EMF of the machine is sinusoidal. This approach results in a smooth torque. However, this restricts the design of the machine and does not utilize the full potential of the power electronics or the controller.
If the design of the machine and the control are carried out together, better system characteristics can be achieved than if the design is carried out separately from the control. This results in a very large potential for developing simpler but also efficient drive systems. This approach has rarely been investigated to date and is covered in this application.
The investigations focus on machines that are designed with non-sinusoidal EMF. These machines are operated in combination with a three-phase four-wire inverter, i.e. with connection of the neutral conductor and a non-sinusoidal coordinate transformation for control. With the aim of obtaining a simpler drive system without a position sensor, sensorless control methods are also being investigated. Since the accuracy of sensorless methods is particularly dependent on the characteristics of the machine, methods for machine design are investigated with regard to improving the capability of sensorless methods.
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The aim of the project is to compare different operating strategies for the operation of combustion engines and electric motors and to identify the advantages and disadvantages. Furthermore, new functions for hybrid drives will be developed which can contribute to the optimization of power supply. Furthermore, electrical actuators for combustion engines will be discussed and optimizations in the field of power electronics and in the control of the electric drive will be carried out. In the end, a new drive concept, the direct coupling of a free-piston motor with a linear generator/motor, will be realized.
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Components such as microcontrollers (µC), digital signal processors (DSP) or field programmable gate arrays (FPGA) are used to control electrical machines. Nowadays, these components usually exceed the computing power required for the main control tasks of the machine. The high computing power available allows the implementation of new functionalities that reduce costs and improve performance. Among these functionalities, sensorless position and speed detection and fault diagnosis can be highlighted.

Sensorless position and speed detection makes it possible to omit the mechanical encoders for controlling the asynchronous machines (sensorless control), thus reducing susceptibility to faults and costs. The diagnosis of incipient faults prevents higher repair costs and breakdowns or major damage to the production plant in which the machine is used.
In the literature, the functionalities mentioned are usually treated separately, although both can benefit from the same methods and models. Therefore, higher quality research results are expected from a joint treatment.
The applicant has developed new methods to improve performance in sensorless position and velocity determination. The cooperation partner has developed new methods for fault diagnosis. Both groups have complementary experience in the research of electrical machines. Collaboration between the two groups will enable increased benefits to be derived from the complementary knowledge in the approach of a joint consideration of sensorless position determination and fault diagnosis.
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The cooperation partner produces blowers in the power range from 1 to 3 kW at speeds of up to 30000 rpm. A single-phase reluctance motor is currently used as the drive motor, which is characterized by a simple design, robustness and low costs. However, due to the principle behind these advantages, significant disadvantages must also be accepted, which manifest themselves in particular in the generation of considerable harmonic torques and noise as well as start-up and heating problems. These problems can be reduced by power electronic means by selecting optimum pulse patterns within certain limits. Due to the operating principle of the single-phase reluctance motor, however, these measures are subject to narrow limits that do not allow a noticeable improvement in operating behavior to be expected. Significantly better properties with regard to its starting behavior and its vibration torques and thus also the heating can be achieved with a multi-phase design, adapted motor geometry and optimum pulse patterns. However, the reluctance principle should be retained due to its simplicity and robustness.
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The position is an important feedback variable for controlled electric drives. Position encoders are normally used for this purpose. However, they are a complex component of the drive. The position encoder and the corresponding signal transmission to the controller are also the cause of increased susceptibility to faults in the drive. In some applications, harsh environmental conditions may also prevent the use of position encoders. However, the position of the motor rotor can also be determined indirectly by measuring only electrical variables, e.g. phase voltage and/or phase current. This method is referred to as sensorless or position sensorless control. Sensorless control has been discussed in scientific literature for two decades, but has hardly been implemented by industry to date. The resulting need for research relates in particular to higher accuracy, dynamics and parameter independence, especially in the lower speed and standstill range.
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