[{"date_created":"2025-12-16T15:20:55Z","type":"conference","keyword":["Cascaded H-Bridge","Current Control","dq Transformation","Linear Regression","Unbalanced Inductors"],"department":[{"_id":"52"}],"publication":"2025 Energy Conversion Congress &amp;amp; Expo Europe (ECCE Europe)","citation":{"bibtex":"@inproceedings{Unruh_Böcker_Schafmeister_2025, title={Three-Phase Instantaneous Current Controller for Unbalanced Grid Inductors Without DQ Transform for Cascaded H-Bridge Converters}, DOI={<a href=\"https://doi.org/10.1109/ecce-europe62795.2025.11238538\">10.1109/ecce-europe62795.2025.11238538</a>}, booktitle={2025 Energy Conversion Congress &#38;amp;amp; Expo Europe (ECCE Europe)}, publisher={IEEE}, author={Unruh, Roland and Böcker, Joachim and Schafmeister, Frank}, year={2025} }","ama":"Unruh R, Böcker J, Schafmeister F. Three-Phase Instantaneous Current Controller for Unbalanced Grid Inductors Without DQ Transform for Cascaded H-Bridge Converters. In: <i>2025 Energy Conversion Congress &#38;amp;Amp; Expo Europe (ECCE Europe)</i>. IEEE; 2025. doi:<a href=\"https://doi.org/10.1109/ecce-europe62795.2025.11238538\">10.1109/ecce-europe62795.2025.11238538</a>","mla":"Unruh, Roland, et al. “Three-Phase Instantaneous Current Controller for Unbalanced Grid Inductors Without DQ Transform for Cascaded H-Bridge Converters.” <i>2025 Energy Conversion Congress &#38;amp;Amp; Expo Europe (ECCE Europe)</i>, IEEE, 2025, doi:<a href=\"https://doi.org/10.1109/ecce-europe62795.2025.11238538\">10.1109/ecce-europe62795.2025.11238538</a>.","chicago":"Unruh, Roland, Joachim Böcker, and Frank Schafmeister. “Three-Phase Instantaneous Current Controller for Unbalanced Grid Inductors Without DQ Transform for Cascaded H-Bridge Converters.” In <i>2025 Energy Conversion Congress &#38;amp;Amp; Expo Europe (ECCE Europe)</i>. IEEE, 2025. <a href=\"https://doi.org/10.1109/ecce-europe62795.2025.11238538\">https://doi.org/10.1109/ecce-europe62795.2025.11238538</a>.","short":"R. Unruh, J. Böcker, F. Schafmeister, in: 2025 Energy Conversion Congress &#38;amp;Amp; Expo Europe (ECCE Europe), IEEE, 2025.","ieee":"R. Unruh, J. Böcker, and F. Schafmeister, “Three-Phase Instantaneous Current Controller for Unbalanced Grid Inductors Without DQ Transform for Cascaded H-Bridge Converters,” presented at the 2025 Energy Conversion Congress &#38; Expo Europe (ECCE Europe), Birmingham, United Kingdom, 2025, doi: <a href=\"https://doi.org/10.1109/ecce-europe62795.2025.11238538\">10.1109/ecce-europe62795.2025.11238538</a>.","apa":"Unruh, R., Böcker, J., &#38; Schafmeister, F. (2025). Three-Phase Instantaneous Current Controller for Unbalanced Grid Inductors Without DQ Transform for Cascaded H-Bridge Converters. <i>2025 Energy Conversion Congress &#38;amp;Amp; Expo Europe (ECCE Europe)</i>. 2025 Energy Conversion Congress &#38; Expo Europe (ECCE Europe), Birmingham, United Kingdom. <a href=\"https://doi.org/10.1109/ecce-europe62795.2025.11238538\">https://doi.org/10.1109/ecce-europe62795.2025.11238538</a>"},"abstract":[{"lang":"eng","text":"Three-phase cascaded H-bridge converters (CHBs) in star configuration require reliable current controllers to evenly charge the module DC-link capacitors. Conventionally, a current control in dq-coordinates is utilized. At steady state, the resulting calculated reference arm voltages are sinusoidal, have identical amplitudes and show a phase shift of 120 degree to each other. For balanced grid inductors, the resulting grid currents also have the same amplitude. However, own simulations show that unbalanced grid inductors always lead to different grid current amplitudes (4% difference in this case). As a result, the averaged charging module powers differ and the peak DC-link capacitor voltage rises as well. In the first step, an adaptation of an existing zero-sequence voltage injection is proposed. For balanced grid inductors, it converges to the 3rd harmonic voltage injection which can reduce the peak-to-peak DC-link voltage ripple up by to 50% and balances the power between the phases. However, unbalanced grid inductors still lead to the same unbalanced grid currents of 4%. Therefore, a new method with 4 integrators based on linear regression is proposed to achieve sinusoidal grid currents for unbalanced inductors. The proposed method has a similar transient dynamic as the conventional dq control, but balances the grid currents nearly ideally. Simulation results of a 1MW cascaded H bridge and a scaled-down prototype verify the proposed method."}],"main_file_link":[{"url":"https://ieeexplore.ieee.org/document/11238538"}],"language":[{"iso":"eng"}],"_id":"63157","publisher":"IEEE","doi":"10.1109/ecce-europe62795.2025.11238538","user_id":"34289","year":"2025","status":"public","title":"Three-Phase Instantaneous Current Controller for Unbalanced Grid Inductors Without DQ Transform for Cascaded H-Bridge Converters","conference":{"location":"Birmingham, United Kingdom","name":"2025 Energy Conversion Congress & Expo Europe (ECCE Europe)","start_date":"2025-09-01","end_date":"2025-09-04"},"author":[{"last_name":"Unruh","first_name":"Roland","full_name":"Unruh, Roland","id":"34289"},{"full_name":"Böcker, Joachim","orcid":"0000-0002-8480-7295","last_name":"Böcker","first_name":"Joachim","id":"66"},{"id":"71291","first_name":"Frank","last_name":"Schafmeister","full_name":"Schafmeister, Frank"}],"date_updated":"2025-12-16T15:25:38Z","publication_status":"published"},{"oa":"1","citation":{"chicago":"Krueger, Alexander, and Reinhold Haeb-Umbach. “Model-Based Feature Enhancement for Reverberant Speech Recognition.” <i>IEEE Transactions on Audio, Speech, and Language Processing</i> 18, no. 7 (2010): 1692–1707. <a href=\"https://doi.org/10.1109/TASL.2010.2049684\">https://doi.org/10.1109/TASL.2010.2049684</a>.","short":"A. Krueger, R. Haeb-Umbach, IEEE Transactions on Audio, Speech, and Language Processing 18 (2010) 1692–1707.","ieee":"A. Krueger and R. Haeb-Umbach, “Model-Based Feature Enhancement for Reverberant Speech Recognition,” <i>IEEE Transactions on Audio, Speech, and Language Processing</i>, vol. 18, no. 7, pp. 1692–1707, 2010.","apa":"Krueger, A., &#38; Haeb-Umbach, R. (2010). Model-Based Feature Enhancement for Reverberant Speech Recognition. <i>IEEE Transactions on Audio, Speech, and Language Processing</i>, <i>18</i>(7), 1692–1707. <a href=\"https://doi.org/10.1109/TASL.2010.2049684\">https://doi.org/10.1109/TASL.2010.2049684</a>","bibtex":"@article{Krueger_Haeb-Umbach_2010, title={Model-Based Feature Enhancement for Reverberant Speech Recognition}, volume={18}, DOI={<a href=\"https://doi.org/10.1109/TASL.2010.2049684\">10.1109/TASL.2010.2049684</a>}, number={7}, journal={IEEE Transactions on Audio, Speech, and Language Processing}, author={Krueger, Alexander and Haeb-Umbach, Reinhold}, year={2010}, pages={1692–1707} }","ama":"Krueger A, Haeb-Umbach R. Model-Based Feature Enhancement for Reverberant Speech Recognition. <i>IEEE Transactions on Audio, Speech, and Language Processing</i>. 2010;18(7):1692-1707. doi:<a href=\"https://doi.org/10.1109/TASL.2010.2049684\">10.1109/TASL.2010.2049684</a>","mla":"Krueger, Alexander, and Reinhold Haeb-Umbach. “Model-Based Feature Enhancement for Reverberant Speech Recognition.” <i>IEEE Transactions on Audio, Speech, and Language Processing</i>, vol. 18, no. 7, 2010, pp. 1692–707, doi:<a href=\"https://doi.org/10.1109/TASL.2010.2049684\">10.1109/TASL.2010.2049684</a>."},"volume":18,"user_id":"44006","_id":"11846","page":"1692-1707","status":"public","department":[{"_id":"54"}],"type":"journal_article","keyword":["ASR","AURORA5 database","automatic speech recognition","Bayesian inference","belief networks","CMLLR","computational complexity","constrained maximum likelihood linear regression","least mean squares methods","LMPSC computation","logarithmic Mel power spectrum","maximum likelihood estimation","Mel frequency cepstral coefficients","MFCC feature vectors","microphone signal","minimum mean square error estimation","model-based feature enhancement","regression analysis","reverberant speech recognition","reverberation","RIR energy","room impulse response","speech recognition","stochastic observation model","stochastic processes"],"date_created":"2019-07-12T05:29:23Z","abstract":[{"lang":"eng","text":"In this paper, we present a new technique for automatic speech recognition (ASR) in reverberant environments. Our approach is aimed at the enhancement of the logarithmic Mel power spectrum, which is computed at an intermediate stage to obtain the widely used Mel frequency cepstral coefficients (MFCCs). Given the reverberant logarithmic Mel power spectral coefficients (LMPSCs), a minimum mean square error estimate of the clean LMPSCs is computed by carrying out Bayesian inference. We employ switching linear dynamical models as an a priori model for the dynamics of the clean LMPSCs. Further, we derive a stochastic observation model which relates the clean to the reverberant LMPSCs through a simplified model of the room impulse response (RIR). This model requires only two parameters, namely RIR energy and reverberation time, which can be estimated from the captured microphone signal. The performance of the proposed enhancement technique is studied on the AURORA5 database and compared to that of constrained maximum-likelihood linear regression (CMLLR). It is shown by experimental results that our approach significantly outperforms CMLLR and that up to 80\\% of the errors caused by the reverberation are recovered. In addition to the fact that the approach is compatible with the standard MFCC feature vectors, it leaves the ASR back-end unchanged. It is of moderate computational complexity and suitable for real time applications."}],"publication":"IEEE Transactions on Audio, Speech, and Language Processing","issue":"7","doi":"10.1109/TASL.2010.2049684","language":[{"iso":"eng"}],"main_file_link":[{"url":"https://groups.uni-paderborn.de/nt/pubs/2010/KrHa10.pdf","open_access":"1"}],"intvolume":"        18","date_updated":"2022-01-06T06:51:11Z","author":[{"first_name":"Alexander","last_name":"Krueger","full_name":"Krueger, Alexander"},{"full_name":"Haeb-Umbach, Reinhold","last_name":"Haeb-Umbach","first_name":"Reinhold","id":"242"}],"year":"2010","title":"Model-Based Feature Enhancement for Reverberant Speech Recognition"},{"department":[{"_id":"54"}],"type":"journal_article","keyword":["acoustic space","adaptation experiments","automatic generation","bottom-up clustering","broad phonetic class regression trees","correlation criterion","correlation methods","maximum likelihood estimation","maximum likelihood linear regression based speaker adaptation","MLLR adaptation","pattern clustering","phonetic regression class trees","speaker-independent training data","speech recognition","speech units","statistical analysis","trees (mathematics)"],"date_created":"2019-07-12T05:28:04Z","abstract":[{"text":"In this paper, it is shown that a correlation criterion is the appropriate criterion for bottom-up clustering to obtain broad phonetic class regression trees for maximum likelihood linear regression (MLLR)-based speaker adaptation. The correlation structure among speech units is estimated on the speaker-independent training data. In adaptation experiments the tree outperformed a regression tree obtained from clustering according to closeness in acoustic space and achieved results comparable with those of a manually designed broad phonetic class tree","lang":"eng"}],"issue":"3","publication":"IEEE Transactions on Speech and Audio Processing","doi":"10.1109/89.906003","language":[{"iso":"eng"}],"main_file_link":[{"open_access":"1","url":"https://groups.uni-paderborn.de/nt/pubs/2001/Ha01.pdf"}],"intvolume":"         9","date_updated":"2022-01-06T06:51:08Z","author":[{"first_name":"Reinhold","last_name":"Haeb-Umbach","full_name":"Haeb-Umbach, Reinhold","id":"242"}],"title":"Automatic generation of phonetic regression class trees for MLLR adaptation","year":"2001","oa":"1","citation":{"bibtex":"@article{Haeb-Umbach_2001, title={Automatic generation of phonetic regression class trees for MLLR adaptation}, volume={9}, DOI={<a href=\"https://doi.org/10.1109/89.906003\">10.1109/89.906003</a>}, number={3}, journal={IEEE Transactions on Speech and Audio Processing}, author={Haeb-Umbach, Reinhold}, year={2001}, pages={299–302} }","ama":"Haeb-Umbach R. Automatic generation of phonetic regression class trees for MLLR adaptation. <i>IEEE Transactions on Speech and Audio Processing</i>. 2001;9(3):299-302. doi:<a href=\"https://doi.org/10.1109/89.906003\">10.1109/89.906003</a>","mla":"Haeb-Umbach, Reinhold. “Automatic Generation of Phonetic Regression Class Trees for MLLR Adaptation.” <i>IEEE Transactions on Speech and Audio Processing</i>, vol. 9, no. 3, 2001, pp. 299–302, doi:<a href=\"https://doi.org/10.1109/89.906003\">10.1109/89.906003</a>.","chicago":"Haeb-Umbach, Reinhold. “Automatic Generation of Phonetic Regression Class Trees for MLLR Adaptation.” <i>IEEE Transactions on Speech and Audio Processing</i> 9, no. 3 (2001): 299–302. <a href=\"https://doi.org/10.1109/89.906003\">https://doi.org/10.1109/89.906003</a>.","short":"R. Haeb-Umbach, IEEE Transactions on Speech and Audio Processing 9 (2001) 299–302.","ieee":"R. Haeb-Umbach, “Automatic generation of phonetic regression class trees for MLLR adaptation,” <i>IEEE Transactions on Speech and Audio Processing</i>, vol. 9, no. 3, pp. 299–302, 2001.","apa":"Haeb-Umbach, R. (2001). Automatic generation of phonetic regression class trees for MLLR adaptation. <i>IEEE Transactions on Speech and Audio Processing</i>, <i>9</i>(3), 299–302. <a href=\"https://doi.org/10.1109/89.906003\">https://doi.org/10.1109/89.906003</a>"},"volume":9,"user_id":"44006","_id":"11778","page":"299-302","status":"public"}]