Institut für leistungselektronische Systeme ELSYS
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- Air conditioning;Electric potential;Biological system modeling;Production;Automobiles;Next generation networking;Engines (1)
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- Batch Gradient Descent (1)
- Couplings ; Switches; Predictive models ; Mathematical model ; Rotors ; Real-time systems ; Prediction algorithmso (1)
- DC power supply ; Design ; Converter circuit ; Measurement ; Power Supply (1)
- DC/DC converter ; efficiency ; tapped transformer ; wide input voltage range (1)
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- Field programmable gate array (1)
- Finite Element Analysis (FEA); Interior Permanent Magnet Synchronous Machine (IPMSM); saturation; cross- coupling; spatial harmonics (1)
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Depending on the application range, there are various recommendations in the literature which converter topology should be used. These are mostly based on experience or more or less deeper considerations. For DC/DC converters, which are operated over a wide input voltage range, such recommendations rarely exist. Therefore, this contribution shows the evolution of two input voltage dependent selection matrices, which should facilitate the selection of future topologies based on known publications and basic considerations. The focus here lies on converters for λ = V i_max /V i_min ≥ 3 with galvanic isolation. First, the data set is introduced, where a distinction is made between flyback converters, forward converters and other 1stage or 2stage converters before the evolution of the novel input voltage dependent matrices is carried out. These two matrices support the selection of a suitable topology and whether the energy transfer should be done by one or two stages.
This paper presents a comparative simulation analysis of an Interior Permanent Magnet Synchronous Machine (IPMSM) performance once fed by a traditional three-phase two-level inverter and then using a three-phase five-level Cascaded H-Bridges Multilevel Inverter (CHBMI). For this purpose, an enhanced mathematical model of the IPMSM, that take into account simultaneously saturation, cross-coupling, spatial harmonics and iron loss effects, has been employed. Furthermore, two different PWM modulation strategies have been considered. The study was conducted for several working conditions, evaluating the impact of CHBMI adoption on the IPMSM performance in terms of improved efficiency and torque ripple reduction.
This paper presents the design, construction and measurements on a transverse flux machine. The lamination concept is designed for easy fabrication and low iron losses. For a good flux guidance and a high magnetic field, electrical sheet is used for the soft magnetic circuit. The design of the machine is performed with a fast semi-analytical calculation and validated by 3D finite element analysis. The calculated quantities are compared with measurements on a prototype. Despite certain deviations, the measurements show good agreement with the calculations for the induced voltage and torque. In terms of efficiency, however, the measurement deviates significantly from the simulation. This is due to the iron losses being calculated much too small, which is evident from the separation of the measured losses.
In this paper, a flux linkage-based direct model predictive current control approach is presented for small permanent magnet synchronous motor (PMSM) drives. The method aims to minimize the current ripples at steady state by deciding on the optimal switching instant, while exhibiting fast dynamic behavior during transients. To this end, the future trajectory of the stator current is not computed based on the machine inductances or inductance look-up tables, but on the changes of the magnetic flux linkage by utilizing flux linkage maps. As shown, the proposed method can be particularly advantageous for electric drives with a noticeable nonlinearity in terms of saturation and/or cross-coupling effects since it allows for a significantly increased prediction accuracy, which leads to an improved steady-state performance as indicated by the reduced current distortions.
A transformer with variable primary windings for wide input voltage range DC/DC converters is presented. This transformer structure allows three states of the primary winding to be converted by only two individual windings. Based on the evaluations of a two-switch flyback converter, the potential of DC/DC converters with variable structures, the implementation of such a transformer and the advantages and disadvantages are shown and discussed. Real measurement results demonstrate the noticeable increase in efficiency and the reduction in component stress, having a positive influence on the operation of the converter and the component selection during the design process.
Machine learning algorithms are increasingly used in industrial applications for a multitude of use-cases. However, using them in control tasks is a challenge due to real-time requirements and limited resources. In this paper, an implementation scheme for real-time inference of multilayer perceptron (MLP) neural networks on FPGAs is proposed. Design constraints for using MLPs in reinforcement learning agents for motor control applications are derived and accounted for in the implementation. Two MLP architectures are evaluated on an FPGA, and the timing and resource-usage data are reported. The real-time capability of the implementation for motor control applications is investigated for standard control frequencies. It is shown by experimental validation that real-time interference with an area-efficient implementation for motor control applications is achievable. Therefore, the proposed implementation scheme can be applied to deep reinforcement learning controllers with hard real-time requirements.
Design of a Wide Input Voltage Range Current-Fed DC/DC Converter Within a Reduced Duty-Cycle Range
(2020)
A design of a current-fed push-pull converter for wide input voltage ranges within a reduced duty-cycle range is presented. Based on the converter conversion ratios of three different clamping configurations, the potential of the input clamping is shown analytical, simulative and by measurements. A differentiation is made between the four possible operating modes, which can be distinguished in the control of the semiconductors and the magnetomotive force in the reactor. By optimizing the turn ratios of both transformers, the wide input voltage range capability of the input clamped current-fed push-pull converter was improved, which has been proved by measurements on a real prototype.
Design Concept of a Wound Field Transverse Flux Machine using Soft Magnetic Composite Claw-Poles
(2020)
This paper presents the machine concept of a wound field transverse flux machine (WFTFM). In contrast to permanent magnet transverse flux machines (PMTFM), here the magneto motive force (mmf) of the rotor is generated by a current. The magnetic circuit of the WFTFM is made of soft magnetic composite (SMC) and is designed as claw-poles. Thus the magnetic circuit consists of only a few components. Together with the simple ring coils in stator and rotor, the WFTFM offers advantages in the production of electrical machines. The basic structure of the machine and a first design is described here. The results generated by numerical three-dimensional finite element analysis (FEA) are compared with those of conventional machines.
This article presents a flux linkage-based direct model predictive current control approach that achieves favorable performance both during steady-state and transient operation. The former is achieved by computing the optimal time instants at which a new switch position is applied to the converter. To this end, the future current behavior is not computed based on the machine inductances or inductance look-up tables; instead, flux linkage maps are utilized to predict the trajectory of the magnetic flux linkage, and subsequently of the current. This is advantageous for electric drives with noticeable magnetic nonlinearity in terms of saturation and/or cross-coupling effects. Hence, by using flux linkage maps in the prediction process, the evolution of the stator current can be calculated more accurately, enabling the controller to make better switching decisions. Moreover, the discussed predictive controller exhibits excellent dynamic performance owing to its direct control nature, i.e., the control and modulation tasks are performed in one computational stage rendering a dedicated modulation stage redundant. Three different drive systems based on permanent magnet synchronous motors are examined to demonstrate the effectiveness of the presented control approach.
n this paper a semi-analytical calculation of a transverse flux machine is presented. First the design of the machine is explained, then the semi-analytical calculation, which is finally compared with a numerical 3D finite element analysis (FEA). The semi-analytical approach is based on a magnetic equivalent circuit, which is solved by nodal analysis and the Broyden-Method. The air gap of the machine is transformed into the magnetic equivalent circuit by conformal mapping using the Schwarz-Christoffel transformation. The comparison to numerical simulation shows that the approach gives good results and is sufficiently accurate for a rough design of the machine.