The rapid adoption of electric vehicles (EVs) has led to a growing demand for fast-charging infrastructure. Such infrastructure in turn poses significant challenges to existing power grids due to high instantaneous power demands. Battery banks can be used as a buffer in a charging station to mitigate the pressure on the grid. This paper develops a method to model and analyze high-power charging stations equipped with a battery bank as energy storage, aiming to support grid stability and maximize economic benefits. Specifically, the study answers (i) how to effectively integrate a high-power battery bank into a high-power charging station, and (ii) how key parameters influence the integration from both operation and economy points of view. Modelled and simulated in MATLAB/Simulink, the proposed approach calculates and analyzes power flow among the grid, the battery bank, and EV batteries, relying on real-time load profiles and battery state-of-charge thresholds. Simulation results show that 1) storing low-cost off-peak energy and 2) discharging of the battery bank during peak grid load periods significantly reduce grid dependency and increase operational profits for the charging station. A parameter-based analysis illustrates that larger battery bank capacities, wider state-of-charge ranges, and narrower grid-load-variation bands benefit both the charging station owner and grid operator.

Electric trucks are becoming more common as means of transporting materials. This study evaluates the use of electric trucks for material transport in Finland. Three battery factories planned in southern Finland, and the raw materials for them are partially transported from other parts of Finland. The trucks can take advantage of the available battery charging stations (BCSs) during the drivers’ mandatory pauses. Another option is to use battery swapping stations (BSSs), if there is not enough time for charging. However, the infrastructure for electric truck charging and battery swapping is still limited. Additional BCSs or BSSs are needed near the raw material factories and along the routes. However, building the facilities is expensive. The aim is to minimize the costs related to charging, while ensuring that the transporting trucks have a sufficient amount of energy to complete the trips.

In this paper a method for segregating losses of a converter-fed induction motor (IM) is proposed. The method does not require the usage of any special hardware that is not readily available in well equipped laboratories. The loss segregation is based on the separation of fundamental loss components and high-frequency harmonic (HFH) losses induced by the pulse width modulation. The tests are carried out using IE3 rated IM at 45 Hz operation point, that is the international efficiency classification point for converter-fed motors. However, the supply frequency is not limited, and the method can be also used to segregate the losses at different operation points. As a reference the standard segregation of losses procedure with 50 Hz sinusoidal supply is presented. The different loss components of the tested IM are presented and analyzed with carrier frequencies of 2 kHz, 4 kHz and 8 kHz. The results behave as expected and the loss segregation procedure looks promising addition to energy efficiency analysis of converted-fed machines.

The frequency converter driven IM can be used as a reference for the efficiency level of a drive system. In here, the losses and efficiency of a 75 kW IE3 -rated modern squirrel-cage induction motor are investigated experimentally. First, the result of IEC loss segregation with sinusoidal supply is used to create a reference point. Secondly, five different commercially available voltage source converters are used to drive the same motor in 30 measurement points up to the rated speed and torque. The losses and efficiencies are analyzed with torque values of 10%, 25%, 50%, 75% and 100% of the rated torque of the motor and supply frequency values of 10%, 25%, 50%, 75%, 90% and 100% of the rated motor frequency. The results are presented as frequency - torque maps and the loss values are given as Table values. Three of these converters show very similar performance from the energy efficiency point of view. The input-output method is used to determine the losses of the motor and converter.

The input-output method is the most frequently used and, in practice, the only viable alternative to determine the losses of all electrical machines regardless of the supply type or motor technology. However, the losses obtained with the input-output method are sensitive to power measurement uncertainties of the input and output powers. The power measurement uncertainty is formed by two parts: type A uncertainty is related to the variations in the measurement data and type B uncertainty is related to measurement instruments. The variations in the data can be controlled using data processing techniques and the type B uncertainty can be controlled using accurate measurement devices and choosing correctly rated measurement instruments for each task. In practice, the range of the instruments is limited and it is not always possible to perfectly match the instruments to the measured values. In here, the effect of the ratings of the instruments on the loss measurement uncertainty when using the input-output method is studied using a set of induction motors with rated powers from 7.5 kW to 355 kW. The specifications of the measurement instruments available at Electric Drives laboratory at LUT-University are used to derive the theoretical loss measurement uncertainty for the motors. The detailed uncertainty analysis includes the electric and mechanical powers, and as a result, loss measurement uncertainty is given. The results can be used to get an overview about the level of the expected measurement uncertainty for motors with different power ratings and its effect on the determination of efficiency.

This paper gives an overview of the calorimetric systems used to determine the losses of converters and motors, introduces the standards in the scope of the topic briefly, and highlights the problems associated with the loss determination of high efficiency devices. The calorimeters are classified in four categories based on chamber configuration. Information about previously published calorimeters is gathered in an easily viewable format. This publication will serve as a quick reference for developing new calorimetric systems.

Electric motors play an important role in global efforts to reduce energy consumption as they account for almost half of the total electrical energy usage in the world. The energy consumption of electric motors can be reduced by using more efficient motors and by applying frequency converters to feed the motors, thereby enabling accurate control according to the load. The induction motor has been - and still is - the dominant motor technology in the industry, but also more efficient motor technologies are available in the market. Considering industrial motors, the two most important competing technologies are probably permanent magnet synchronous motors and synchronous reluctance motors. This papers provides a comparison between the induction motor and synchronous reluctance motor technologies. The main differences between the two are covered and measurements are made with a frequency converter supply to compare the efficiencies over a wide operating range of 10-100% of rated torque and 10-140% of rated operating frequency.

This paper studies the effect of different slice count on quality of multi-slice simulation. The slices are distributed evenly along the axial length of the machine. The torque and current waveforms at nominal point are analysed for different numbers of slices, and compared with the measured waveforms. Practical optimum is identified finding a trade-off between simulation time and results quality.

The pulse-width-modulation is used to create a desired amplitude and frequency voltage waveform to feed the motor in different operating points. There are different modulation methods of how to create the desired waveforms. In this paper, waveforms recorded from two-level voltage-source converters with three different modulation methods are analyzed. The voltage and current waveforms are transformed to the frequency domain and the power distribution in the frequency domain is examined. An algorithm to extract the true applied switching frequency is presented. The analysis is performed using 50 Hz output frequency and the load torque values of 100 %, 75 %, 50 %, 25 % and the no-load condition with all three modulation methods. Finally, the effect of the THD calculation procedure to the THD-value is examined and the THD values are compared to other loss indicators of the motor.

Accurate measurement of power losses of high efficiency motors and converters is difficult and extra challenge is caused by pulse-width-modulated (PWM) signals. Soon, the converter-fed motors, converters, and power drive systems will get their own efficiency classifications. Also, the methods how the device losses shall be determined are given in corresponding standards. This paper presents 37 kW induction motor loss measurement results with sinusoidal and PWM supply. Five different commercial frequency converters are used to obtain single motor losses.

Accurate measurement of losses of high-efficiency power electronics devices and electrical motors is difficult by using input and output powers. In the calorimetric method, these losses are measured directly. However, the calorimeters have to be designed for a certain power loss range, and therefore, the same system cannot be applied to different power devices. In this paper, a functional and scalable power loss measurement concept is suggested for the measurement of losses between 10 W and 30 kW with a reasonable measurement accuracy. Such a power loss range can be applied, for example, to devices with 97% efficiencies with input powers between 333 W and 1 MW. The concept is introduced, verified, and demonstrated by laboratory measurements.