# Christoph Michael HacklMunich University of Applied Sciences | HM · Institute for Sustainable Energy Systems (ISES)

Christoph Michael Hackl

Prof. Dr.-Ing. habil.

We are currently working on efficient, fault-tolerant and self-learning electrical drives and renewable energy systems.

## About

314

Publications

126,900

Reads

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3,963

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Introduction

I am a Professor at HM Munich University of Applied Sciences, Germany. I head the "Laboratory for Mechatronic and Renewable Energy Systems (LMRES)" and co-head the "Institute for Sustainable Energy Systems (ISES)". My research foci are modelling, control, extended functionality, optimal operation and design of the electrical components of renewable and mechatronic energy systems (e.g. wind/wave/PV/geothermal energy conversion systems or electric vehicles). Contact me via Email only please!

Additional affiliations

October 2019 - present

February 2018 - present

May 2017 - July 2017

**CREATE Singapore**

Position

- Lecturer

Education

December 2014 - May 2019

**Technical University of Munich, Department of Electrical and Computer Engineering**

Field of study

- Mechatronic and Renewable Energy Systems

## Publications

Publications (314)

A unified theory for optimal feedforward torque control of anisotropic synchronous
machines with non-negligible stator resistance and mutual inductance is presented
which allows to analytically compute (i) the optimal direct and quadrature reference
currents for all operating strategies, such as Maximum Torque per Current (MTPC),
Maximum Current (M...

The mathematical modeling of open-switch faults in two-level machine-side converters and the fault-tolerant current control of isotropic permanent-magnet synchronous generators are discussed. The proposed converter model is generic for any open-switch fault and independent of the operation mode of the electrical machine. The proposed fault-tolerant...

This paper proposes modified Second-Order Gener-
alized Integrators (mSOGIs) for a fast estimation of all harmonic
components of arbitrarily distorted single-phase signals such
as voltages or currents in power systems. The estimation is
based on the internal model principle leading to an overall
observer consisting of parallelized mSOGIs. The obser...

A novel Artificial Neural Network (ANN) Based Optimal Feedforward Torque Control (OFTC) strategy is proposed which, after proper ANN design, training and validation, allows to analytically compute the optimal reference currents (minimizing copper and iron losses) for Interior Permanent Magnet Synchronous Machines (IPMSMs) with highly operating poin...

Electrical drives consume more than 50% of the globally generated electricity. Hence, advances in research on modelling, control and operation of electrical drives (machine+inverter) have been made.
This tutorial covers all aspects of modern electrical drives such as:
- nonlinear modelling and dynamic simulation of the electro-mechanical system con...

Due to the complex rotor design of reluctance synchronous machines, a finite element analysis is essential for the accurate calculation of machine relevant performance objectives. Reluctance synchronous machines tend to have a large torque ripple, if this objective is not considered during the machine design. This necessitates a large number of sim...

An optimal reference voltage saturation (ORVS) for nonlinear current control of synchronous machine drives is presented. It is integrated into a nonlinear current control system based on input/output (I/O) linearization and proportional-integral (PI) controllers with anti-windup. The ORVS is derived from an optimization problem that can be solved a...

Multi-objective hyperparameter optimization (MO-HPO) is applied to find optimal artificial neural network (ANN) architectures used for optimal feedforward torque control (OFTC) of synchronous machines. The proposed framework allows to systematically identify Pareto optimal ANNs with respect to multiple (partly) contradictory objectives such as appr...

Renewable inverter-based resources (IBRs), such as wind energy conversion systems (WSs), replace directly grid-connected synchronous machines (SMs). Standard grid-following (GFL) control of IBRs decreases the power system inertia. This paper proposes virtual synchronous machine (VSM) based grid-forming (GFM) control for doubly-fed induction machine...

High-frequency signal injection (HFSI) methods are generally used for sensorless control of electrical machines at standstill and in the low-speed range. For electrically excited synchronous machines (EESMs), the rotor circuit is in the form of buck converter and the modulated rotor switching signals have high frequency. Utilizing these signals all...

Due to the complex rotor design of reluctance synchronous machines, a finite element analysis is essential for the accurate calculation of machine relevant performance objectives, like mean torque and torque ripple. This necessitates a large number of simulation steps, resulting in a high computational burden and a long simulation time per design e...

p>Multi-objective hyperparameter optimization (MO-HPO) is applied to find optimal artificial neural network (ANN) architectures used for optimal feedforward torque control (OFTC) of synchronous machines. The proposed framework allows to systematically identify Pareto optimal ANNs with respect to multiple (partly) contradictory objectives such as ap...

p>Multi-objective hyperparameter optimization (MO-HPO) is applied to find optimal artificial neural network (ANN) architectures used for optimal feedforward torque control (OFTC) of synchronous machines. The proposed framework allows to systematically identify Pareto optimal ANNs with respect to multiple (partly) contradictory objectives such as ap...

A Continuous-Control-Set Model Predictive Control (CCS-MPC) proposed for DC-DC converters for EV powertrains based on Gallium Nitride High Electron Mobility Transistors (GaN HEMTs) devices is presented in this work. The CCS-MPC allows full control of system states by adopting a multi-objective control approach, ensuring optimal power exchange betwe...

This index covers all technical items—papers, correspondence, reviews, etc.—that appeared in this periodical during 2023, and items from previous years that were commented upon or corrected in 2023. Departments and other items may also be covered if they have been judged to have archival value. The Author Index contains the primary entry for each i...

For electrically excited synchronous machines (EESMs) used in automotive applications, the flux linkages are highly nonlinear due to magnetic saturation and cross-coupling effects. Therefore, the inductances strongly depend on the actual current operating point. For sensorless control and/or observer design, the inductances are usually read from lo...

p>Facing the climate crisis, more and more renewable inverter-based resources (IBRs), such as wind energy conversion systems (WSs), replace grid-connected synchronous machines (SMs). SMs inherently provide balanced and sinusoidal grid voltages but also power system inertia, whereas standard grid-following (GFL) control of IBRs leads to decreasing p...

Facing the climate crisis, more and more renewable inverter-based resources (IBRs), such as wind energy conversion systems (WSs), replace grid-connected synchronous machines (SMs). SMs inherently provide balanced and sinusoidal grid voltages but also power system inertia, whereas standard grid-following (GFL) control of IBRs leads to decreasing pow...

The proposed identification method allows for a simultaneous estimation of nonlinear output voltage deviations in voltage source inverters (VSIs) and nonlinear synchronous machine models. Based on the identified characteristics with the help of physically inspired structured artificial neural networks (ANNs), an efficient tuning of the current cont...

p>Modular Multilevel Cascade Converters (MMCCs) are considered a promising power electronics topology in industry. Their scalability allows to reach (ultra/very) high voltage levels with low harmonic content and high efficiency and makes MMCCs an ideal solution for high-power applications; such as electrical drives, solid-state transformers and hig...

p>Modular Multilevel Cascade Converters (MMCCs) are considered a promising power electronics topology in industry. Their scalability allows to reach (ultra/very) high voltage levels with low harmonic content and high efficiency and makes MMCCs an ideal solution for high-power applications; such as electrical drives, solid-state transformers and hig...

The inevitable transition of the power system toward a sustainable and renewable-energy centered power system is accompanied by huge versatility and significant challenges. A corresponding shift in operation strategies, embracing more intelligence and digitization, e.g., a Cyber-Physical System (CPS), is needed to achieve an optimal, reliable and s...

p>This paper presents a self-identification approach for reluctance synchronous machines (RSMs) in combination with analytical flux linkage prototype functions. Due to the severe magnetic saturation, good machine knowledge is required for high-performance electrical drive systems. The proposed self-identification method injects bipolar voltage puls...

p>This paper presents a self-identification approach for reluctance synchronous machines (RSMs) in combination with analytical flux linkage prototype functions. Due to the severe magnetic saturation, good machine knowledge is required for high-performance electrical drive systems. The proposed self-identification method injects bipolar voltage puls...

p>A generic current control system for modular multilevel cascade converters (MMCCs) is proposed. It is based on (i) input/output-linearization (I/O-linearization), (ii) feedforward disturbance compensation and (iii) parallelized proportional-integral-resonant controllers to compensate for arbitrarily many harmonics (including positive and negative...

p>A generic current control system for modular multilevel cascade converters (MMCCs) is proposed. It is based on (i) input/output-linearization (I/O-linearization), (ii) feedforward disturbance compensation and (iii) parallelized proportional-integral-resonant controllers to compensate for arbitrarily many harmonics (including positive and negative...

p>With the decreasing number of directly grid-connected synchronous machines (SMs) forming the grid voltage, the risk of power system instability increases, especially regarding the grid frequency due to the decreasing power system inertia. Grid-forming (GFM) control of inverter based resources (IBRs) with inertia emulation capability is required t...

p>With the decreasing number of directly grid-connected synchronous machines (SMs) forming the grid voltage, the risk of power system instability increases, especially regarding the grid frequency due to the decreasing power system inertia. Grid-forming (GFM) control of inverter based resources (IBRs) with inertia emulation capability is required t...

p>Synchronous machines (SMs) like reluctance synchronous machines (RSMs) or interior permanent magnet synchronous machines (IPMSMs) are characterized by nonlinear stator flux linkages which are crucial for optimal control and operation management. This paper presents a novel disturbance observer that allows to estimate the nonlinear flux linkages o...

p>Synchronous machines (SMs) like reluctance synchronous machines (RSMs) or interior permanent magnet synchronous machines (IPMSMs) are characterized by nonlinear stator flux linkages which are crucial for optimal control and operation management. This paper presents a novel disturbance observer that allows to estimate the nonlinear flux linkages o...

p>Reluctance synchronous machines (RSMs) are characterized by high nonlinearities, cross-coupling effects and high torque ripple. This paper presents a nonlinear machine model of three-phase RSMs based on a nonlinear electromagnetic model including iron losses and a novel (extended) torque equation. The γ-component is used to consider asymmetries....

p>Reluctance synchronous machines (RSMs) are characterized by high nonlinearities, cross-coupling effects and high torque ripple. This paper presents a nonlinear machine model of three-phase RSMs based on a nonlinear electromagnetic model including iron losses and a novel (extended) torque equation. The γ-component is used to consider asymmetries....

p>An Artificial Neural Network (ANN) based Optimal Feedforward Torque Control (OFTC) strategy for electrically excited synchronous machines (EESMs) is proposed. After design, data set creation, training and validation of the ANN, the analytical computation of the optimal stator and exciter currents is achieved which allows to minimize copper and ir...

p>An Artificial Neural Network (ANN) based Optimal Feedforward Torque Control (OFTC) strategy for electrically excited synchronous machines (EESMs) is proposed. After design, data set creation, training and validation of the ANN, the analytical computation of the optimal stator and exciter currents is achieved which allows to minimize copper and ir...

p>Modular Multilevel Cascade Converter (MMCC) have achieved a great importance in high voltage converter applications. As they require a high amount of capacitors whose voltages must be known for the control of the MMCC, many voltage sensors are needed. This paper presents a nonlinear Lyapunov-based observer for cell voltage estimation. The propose...

p>Modular Multilevel Cascade Converter (MMCC) have achieved a great importance in high voltage converter applications. As they require a high amount of capacitors whose voltages must be known for the control of the MMCC, many voltage sensors are needed. This paper presents a nonlinear Lyapunov-based observer for cell voltage estimation. The propose...

For electrically excited synchronous machines (EESMs) used in automotive applications, the flux linkages are nonlinear and the magnetic saturation plays an important role. The coupling between
$d$
-axis and exciter axis in EESMs introduces a significant fluctuation of the flux linkages due to current changes. To cope with these problems, a novel...

This paper proposes a dual-vector finite-control-set model predictive control (FCS-MPC) with reduced complexity for a novel nine-level active neutral point clamped (ANPC) converter. This topology considerably reduces the used number of power switches compared to other topologies. Only nine power switches and two flying capacitors (FCs) are used to...

This contribution presents the control of the electrical system of a Wave Energy Converter (WEC) prototype developed by SINN Power. Due to the movement of the waves, the generated power has a very high fluctuation with a period of a few seconds. To be able to use this power, it has to be smoothed. The used Energy Storage System (ESS) is a supercapa...

The paper proposes a nonlinear current control system of reluctance synchronous machines (RSMs) in combination with analytical flux linkage prototype functions. For highly nonlinear machines, such as RSMs, the magnetic characteristics change significantly throughout the whole operation range due to saturation and cross-coupling effects. Therefore,...

Modular Multilevel Cascade Converters (MMCCs) are considered a promising power electronics topology in industry. Their scalability allows to reach (ultra/very) high voltage levels with low harmonic content and high efficiency and makes MMCCs an ideal solution for high-power applications; such as electrical drives, solid-state transformers and high-...

Modular multilevel cascade converters (MMCCs) are considered a promising power electronics topology in industry. Their scalability allows to reach (ultra/very) high voltage levels with low harmonic content and high efficiency and makes MMCCs an ideal solution for high-power applications; such as electrical drives, solid-state transformers, and high...

This article presents a real-time realization of a continuous-control-set model predictive current controller for the two types of permanent magnet synchronous machines: 1) surface-mounted permanent magnet synchronous machine (SMPMSM) and 2) interior permanent magnet synchronous machine (IPMSM). The constrained optimization problem is solved online...

This paper discusses the MPPT based on finite‐set model predictive control (FS‐MPC) in photovoltaic (PV) systems. Generally, the FS‐MPC implementation needs more sensors in comparison with the traditional methods due to the existence of the prediction stage. However, it has a fast transient behaviour in case of fast‐changing atmospheric conditions....

This article proposes a novel hybrid nine-level inverter for high-efficiency applications based on the popular five-level active-neutral-point-clamped (5L-ANPC) topology. Compared with conventional ANPC-based topologies, this inverter reduces the required number of active and passive components while avoiding the use of higher voltage switches. Onl...

Due to its merits of fast dynamic response, flexible inclusion of constraints and the ability to handle multiple control targets, model predictive control has been widely applied in the symmetry topologies, e.g., electrical drive systems. Predictive current control is penalized by the high current ripples at steady state because only one switching...

A speed-sensorless state-feedback controller for induction machines (IMs) with LC filter is proposed. The speed and state estimation is based on a speed-adaptive observer, requiring only the measurement of the filter input currents. The motor currents are controlled by a state-feedback controller with prefilter and integral control action, in order...

A novel but simple machine map-based modeling, identification, and optimal feedforward torque control (OFTC) approach for induction machines (IMs) is presented. It is based on, first, a generic, nonlinear transformer-like machine model considering nonlinear flux linkages (with magnetic saturation and cross coupling) and iron losses in the stator la...

Physically motivated and analytical prototype functions are proposed to approximate the nonlinear flux linkages of nonlinear synchronous machines (SMs) in general; and reluctance synchronous machines (RSMs) and interior permanent magnet synchronous machines (IPMSMs) in particular. Such analytical functions obviate the need of huge lookup tables (LU...

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A not yet available look-up table (LUT) based optimal feedforward torque control (OFTC) method for squirrel- cage induction machines (SCIMs) is presented. It is based on: (i) a generic transformer-like machine model in an arbitrarily rotating (d,q)-reference frame, considering nonlinear flux linkages and iron losses in the stator laminations;...

The efficiency of an IPMSM motor is influenced by the operating point of the machine. Conventional approaches to generate measured efficiency maps may be too expensive to use in some situations, thus it often replaced by simpler variants based on parametric models. A promising approach is to combine model-based approaches with online parameter iden...

In this paper, a deadbeat predictive control (DBPC) technique for doubly-fed induction generators (DFIGs) in wind turbine applications is proposed. The major features of DBPC scheme are its quick dynamic performance and its fixed switching frequency. However, the basic concept of DBPC is computing the reference voltage for the next sample from the...

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A not yet available look-up table (LUT) based optimal feedforward torque control (OFTC) method for squirrel- cage induction machines (SCIMs) is presented. It is based on: (i) a generic transformer-like machine model in an arbitrarily rotating (d,q)-reference frame, considering nonlinear flux linkages and iron losses in the stator laminations;...

div>
A not yet available look-up table (LUT) based optimal feedforward torque control (OFTC) method for squirrel- cage induction machines (SCIMs) is presented. It is based on: (i) a generic transformer-like machine model in an arbitrarily rotating (d,q)-reference frame, considering nonlinear flux linkages and iron losses in the stator laminations;...

In this article, a deadbeat predictive control (DB-PC) strategy for permanent-magnet synchronous generators (PMSGs)-based modern wind turbines is proposed. The main advantages of the DB-PC technique are its excellent dynamics and its constant switching frequency. However, the main idea of DB-PC is obtaining the actuation voltage for the next sample...

An accurate approximation of the dc-link ca- pacitor current is crucial for the design of the dc-link capacitor as the capacitor current ripple affects lifetime, size, weight and cost of the voltage source inverter (VSI). In this paper, analytical expressions for the dc-link capacitor current and the inverter current are derived for two-level VSIs...