ILE – Institut für Leistungselektronik
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FHA-Model Based Comparison of Different Control Techniques for Wireless Power Transfer Systems
(2025)
Wireless Power Transfer (WPT) is a technology that is becoming increasingly important. For example, it is used for charging consumer electronics such as smartphones to enhance convenience but also for battery electric vehicles to improve their availability and range. Many different control strategies have already been investigated for WPT systems and their feasibility have been proven. This paper presents a comparison of 3 different control strategies based on the First Harmonic Approach (FHA) model. The main variables considered are the primary and secondary resonance tank currents, as these are either linear or quadratic in any power transfer system losses. Therefore, it gives insight into which operation strategy offers a higher or lower efficiency or allows a reduction in component stress. To provide a basic insight into these control strategies which offer different control parameters, they are briefly introduced. Since these parameters as well as the compensation in the resonance tanks are decisive for the performance of the system, the selection of these quantities is done by optimization. These optimization problems are also addressed in this paper.
This paper presents a novel Interleaved Bidirectional DC-DC Converter (IBDC) designed to improve the efficiency of testing electric vehicle (EV) batteries. The proposed system facilitates energy exchange between batteries during the charging and discharging phases, crucial for battery testing and evaluation.
The converter leverages Silicon Carbide (SiC) MOSFETs to achieve high efficiency and fast switching transitions. At the same time, the interleaving technique is employed to increase power handling capacity and reduce current ripple, enhancing overall system performance. A 70-kW prototype of the converter was designed, simulated, and implemented to validate the proposed architecture. In addition, a robust control strategy was developed to ensure stable bidirectional power flow.
FEM Temperature Simulation of a PMSM with a Temperature Dependent Lookup Based MTPA Control Approach
(2025)
In electric vehicles, a permanent magnetic synchronous motor is mostly used. For optimal control the temperature of the permanent magnets is estimated with a temperature observer model. However, due to inaccurate models, there will be a deviation between actual temperature and estimated temperature. A sensor placed in the rotor gives a precise temperature value, which maximizes power utilization by minimizing thermal reserves. In this paper, an electrical simulation with a temperature correction scheme is set up, which in combination with a FEM simulation estimates the hottest spot in the rotor. The simulations generate information for ideal mounting positions for a temperature sensor and the electromagnetic and thermal boundary conditions that occur at these spots.
Resonant-based power converters are widely adopted due to their ability to achieve high efficiency through soft switching techniques, particularly zero voltage switching (ZVS). However, these converters often require additional components such as inductors, capacitors, transformers, diodes and active switches, which complicate the design and increase the size of the converter. This paper investigates the conditions for naturally achieving ZVS in a GaN-based Power factor correction or boost converter, utilizing parasitic capacitance of switch and boost inductor, reducing switching losses and EMI while enhancing power density and efficiency. The paper proposes a technique that ensures ZVS without adding any additional components even when inherent conditions are not satisfied, by driving the input inductor current negative before turning off the high-side switch. The proposed methodology is validated through comprehensive mathematical analysis, and experimental results and compared with normal MOSFETs using simulations demonstrating its effectiveness in enhancing converter performance.
Es wird auf die Unterschiede von trafobehafteten und trafolosen Wechselrichtern und die daraus resultierenden, wesentlichen Merkmale eingegangen. Die kapazitiven Umladeströme, hervorgerufen durch die im Solargenerator befindlichen Kapazitäten machen eine bipolare Taktung bei der H-Brücke oder eine andere Topologie notwendig. Daraus resultieren auch unterschiedliche Belastungen in den passiven Bauelementen. Hier wird im Wesentlichen auf die Zwischenkreisströme eingegangen.
In recent years the undisturbed electrical power supply became very important, because of the increasing automation (Schmidt, et al., 1995). A protected electrical power supply is possible by using a static uninterruptible power supply (UPS), because its electrical energy is stored in a DC-link intermediate circuit, connected with a battery. An important cost factor and power loss producer is the usually inserted line frequency output transformer. The elimination of the transformer causes a changing of the circuit topology and a rising of the DC-link voltage. It is possible to omit the transformer by connecting the ground wire of the load to the centre point of the DC-link capacitor. The DC-link voltage has to be higher than the sum of the peak value of the sinusoidal output voltage and the voltage drop of the output filter inductance at maximum load (e.g. U/sub d/= 800 V) (Patt, M, 2002). A second cost factor is the DC-link capacitor. Its reactive power capacity becomes bigger compared to conventional UPS because the low-frequency load current flows through the centre point of the DC-link capacitors. This is an essential and an expenditure property (F. Renken et al., 2002). The centre of the paper is the analysis of the DC-link capacitor current in different topologies. In the first part of the analysis the current-loading of a two and a three level voltage source inverter will be described. In the second part of the paper a three phase two-level and a three phase three level-inverter will be compared.