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This paper proposes a method to design an electrical variable transmission (EVT) of which the stator and inner rotor contain a distributed three-phase winding, and the outer rotor is equipped with permanent magnets and a dc-field winding. The main problem with the design of EVTs is that the modeling relies on time-consuming finite-element (FE) calculations. Studying the effect of design changes is, therefore, a cumbersome task. To minimize the need for FE calculations, scaling laws are applied, which reduce the computational effort to a matter of milliseconds per design. Therefore, the losses of multiple scaled designs can be analyzed for a given load cycle while taking constraints into account such as maximum torque. By presenting this data in a performance map, the optimal design regarding the losses is easily deduced. To validate the presented methodology, FE calculations, measurements, and available literature are used.

The series-parallel architecture is the most interesting for hybrid electric vehicles, allowing the lowest fuel consumption. Unlike passenger cars, this architecture is not commercially available on the heavy-duty vehicles market. This is due to technical limitations associated with unsufficient load capability of the geartrain. To address this issue, new transmissions, such as the electrical variable transmission, have been developed. The novelty of this paper relies on the hybridization of a long-haul truck using the electrical variable transmission. This study aims to investigate the potential of using this new transmission for trucks. For that aim, fuel consumption benchmarking of three powertrain topologies is performed, considering: (a) a gearless topology; (b) a geared topology that uses one gearbox inserted between the engine and the mechanical input port of the electrical variable transmission; (c) a geared topology similar to the second one, but, with an additional multi-stage gearbox inserted to the mechanical output port of the electrical variable transmission. For a fair comparison between the different topologies, a bi-level optimization process has been used, incorporating the optimization of both components sizing and control. Results show that the fuel consumption of the gearless powertrain is higher than the engine-powered truck due to higher losses in the electrical variable transmission. While maximum fuel reduction of 14.2% was obtained by a geared topology that uses two gearboxes. Furthermore, emphasis is given to understand the effect of the powertrain component sizing on fuel consumption. Depending on the defined sizing, a possible fuel reduction is achieved from 3.3% to 14.2% for the two geared topologies. The reduction of CO2 emissions is found to be proportional to the fuel savings. Considering a long-haul mission, the last findings prove that the electrical variable transmission exhibits potential to reduce fuel consumption, if an adequate powertrain topology and its sizing are well defined.

The bearings of rotating machinery often fail, leading to unforeseen downtime of large machines in industrial plants. Therefore, condition monitoring can be a powerful tool to aid in the quick identification of these faults and make it possible to plan maintenance before the fault becomes too drastic, reducing downtime and cost. Predictive maintenance is often based on information gathered from accelerometers. However, these sensors are contact-based, making them less attractive for use in an industrial plant and more prone to breakage. In this paper, condition monitoring based on ultrasound is researched, where non-invasive sensors are used to record the noise originating from different defects of the Machinery Fault Simulator. The acoustic data are recorded using a sparse microphone array in a lab environment. The same array was used to record real spatial noise in a fully operational plant which was later added to the acoustic data containing the different defects with a variety of Signal To Noise ratios. In this paper, we compare the classification results of the noisy acoustic data of only one microphone to the beamformed acoustic data. We do this to investigate how beamforming could improve the classification process in an ultrasound condition-monitoring application in a real industrial plant.

In this paper, an innovative model structuration is proposed to describe scaled Permanent Magnet Synchronous Machines (PMSM) at system level. By using the Energetic Macroscopic Representation formalism (EMR), the equations of the scaling laws are reorganized. The restructuration consists of a reference PMSM model complemented with two electrical and mechanical power adaptation elements. These latter elements take care of the scaling effects, including the power losses. The methodology is applied to scale the power of a PMSM for an electric vehicle, by a factor of 2. According to the studied designs, an average efficiency from 83.7% to 87.1% is obtained during an urban driving cycle.

This paper evaluates the performance of Silicon Carbide MOSFET and Silicon IGBT modules in a three-phase inverter for Electrical Variable Transmission systems. For this purpose, two practical inverter setups were developed and compared. An increase of several percentage points is visible over the entire operating range for the Silicon Carbide prototype. The total energy efficiency increased by 3.7% for the rotor and by 11.2% for the stator, for the same test conditions.

The push for less emissions has driven transportation towards electrification. The electrical variable transmission is a promising emerging component that has proven to be successful in passenger vehicles and is being considered in this paper for off-highway vehicles. By electromagnetically coupling the internal combustion engine with the wheels, allowing independent rotation, the engine is kept in its optimal operating range. This paper benchmarks the electrical variable transmission to one of the most successful hybrid topologies: the Toyota hybrid system. Flanders Make’s Hybrid Electric Drivetrain CoDesign framework is being used to ensure optimal control decisions for both. Results show that the electrical variable transmission may reduce fuel consumption by 30% and total cost of ownership by 10%.

The energy management strategy (EMS) or power management strategy (PMS) unit is the core of power sharing control in the hybridization of automotive drivetrains in hybrid electric vehicles (HEVs). Once a new topology and its corresponding EMS are virtually designed, they require undertaking different stages of experimental verifications toward guaranteeing their real-world applicability. The present paper focuses on a new and less-extensively studied topology of such vehicles, HEVs equipped with an electrical variable transmission (EVT) and assessed the controllability validation through hardware-in-the-loop (HiL) implementations versus model-in-the-loop (MiL) simulations. To this end, first, the corresponding modeling of the vehicle components in the presence of optimized control strategies were performed to obtain the MiL simulation results. Subsequently, an innovative versatile HiL test bench including real prototyped components of the topology was introduced and the corresponding experimental implementations were performed. The results obtained from the MiL and HiL examinations were analyzed and statistically compared for a full input driving cycle. The verification results indicate robust and accurate actuation of the components using the applied EMSs under real-time test conditions.

The snakeboard is a fascinating variation of the well-known classic skateboard, and a nonholonomic structure. Therefore, a snakeboard robot is appealing for usage in control engineering education. The propulsion, which relies on cyclic movements, resembles that of many biological creatures. Hence, the challenging snakeboard modelling and motion planning received much attention in literature during the last decades. Despite all these research efforts, there is no model available in which there is a clear link between the mathematical descriptions and physical phenomena. The lack of physical insights hampers the development of a closed-loop real-time trajectory controller which is apparent by the lack of literature on such algorithms for snakeboards. In this paper, the traditional models are rewritten to obtain a model with a clear link to physical phenomena. Based on this model a closed loop controller is designed. Moreover, this rewritten model delivers the insights on actuation efficiency which are used to adapt desired trajectories a priori to more energy-efficient forms. Finally, the control and trajectory optimisation is validated by measurements on a snakeboard robot. (C) 2018 European Control Association. Published by Elsevier Ltd. All rights reserved.

The mechanical dynamics of modern machines very often depend on the angular position of the driven axis. To obtain optimal control, such applications typically require an advanced control structure such as an adaptive controller. Moreover, the variation in the dynamics like changing inertia, load torque, and viscous friction limits the performance and reduces the energy efficiency. Energy savings can be obtained by using so-called trajectory optimization techniques combined with feedforward control. However, both optimization and adaptive control require the knowledge of the position dependency of the mechanical parameters. In the case of reciprocating mechanisms, for instance, this position dependency is significant. Consequently, the mechanical parameters change rapidly at high operating speed of the machine. This paper thus contributes towards fast and accurate estimation of rapidly varying mechanical parameters. A sliding discrete Fourier transform (SDFT) approach is proposed to track the inertia variation of a reciprocating mechanism online. The feasibility is verified with experiments on an industrial pick and place unit. Both the results on the real machine and its CAD equivalent, modelled in a multibody dynamics software package, are considered. In addition, the developed inertia tracking algorithm is proven to be implementable in standard commercial drive components. Post-print / Final draft

Nowadays, most brushless DC (BLDC) motors use Hall sensors or sensorless algorithms based on back-electromotive force (back-EMF) sensing to detect rotor position information. These methods detect the commutation moments but imply the use of rectangular stator currents which, according to recent literature, limits the energy efficiency. In this study, sinusoidal stator currents are used to increase the motor energy efficiency. As a consequence, standard control based on the feedback of the Hall sensors or based on sensorless techniques detecting the back-EMF zero-crossing cannot be used. Therefore, the authors propose a load angle control algorithm for BLDC motors without using position and speed sensors. The objective is to obtain energy-efficient sensorless control for the BLDC motor based on the measurement of only two current and one voltage signal. The energy saving potential of the proposed method is especially outspoken for fixed speed applications with varying loads, which are typical BLDC applications. Experimental results are presented to validate the proposed method. Energy efficiency measurements over the whole operating range of the BLDC motor are included and show an energy saving potential up to 9.5%.

The full and half toroidal CVT have been the subject for many research papers. The efficiency and behavior in steady state of both topologies has already been discussed in detail but until now no special attention has been given to their behavior during ratio variation. Therefore, this paper discusses the comparison of the full and half toroidal CVT during periods of ratio variation focusing on the dynamic response and efficiency. The geometrical constraints for the comparison are as follows: equal output inertia, equal maximum output torque at a speed ratio of 1 and identical radial size. The results of the study are based on a model that describes the behavior of both topologies and an algorithm that determines the optimal ratio variation. The outcome of the study shows that the half toroidal outperforms the full toroidal CVT over the entire operating range in terms of dynamics and efficiency during ratio variation.

Stepping motors are used in numerous applications because of their low manufacturing cost and simple open-loop position control capabilities. The bulk of the widely used full-step open-loop stepping motor drive algorithms are driven at maximum current to avoid step loss. This non-optimal way of control leads to low efficiency. In order to use stepping motors in a more optimal way, closed-loop control is needed. A previously described sensorless load angle estimation algorithm, solely based on voltage and current measurements, is used to provide the necessary feedback without using a mechanical position sensor. In this paper, an adaptive PI controller which optimizes the current level based on the feedback of the estimated load angle is introduced. Although the current - load angle dynamics are highly non-linear, an adaptive PI controller with the settling time of the current reduction as design constraint is worth considering. Especially because few tuning parameters are required. The described method is complimentary to the popular methodology used to drive a stepper motor, which is based on step command pulses. Measurements validate the proposed approach.

In most applications where a variable transmission is required, either an EVT or a CVT would be viable options. In order to obtain a justified decision between both variable transmissions, the operating range and efficiency should be known better. To be able to pinpoint the pros and cons based on efficiency and operating range, a detailed comparison is necessary. However, to the knowledge of the authors there is no such study reported in literature so far. In this paper a permanent magnet Electrical Variable Transmission (EVT) is benchmarked against a half toroidal Continuously Variable Transmission (CVT) and this during steady state conditions. This paper provides the constraints for the comparison and results based on detailed models of both technologies. Two comparative studies are carried out: on one hand a study based on equal maximum output torque and on the other hand a study based on equal rated power. The outcome of the study shows that the CVT is in favor for high input torques and that the EVT is dominant for high input speeds.

The present study assesses utilization of an Electrical Variable Transmission system for application in the drivetrain of a hybrid electric city bus. To this end, first the corresponding modeling for a hybrid bus topology is performed in presence of a gearbox. Secondly, two optimization-based energy management strategies (EMS) coupled into a Rule-based EMS are examined. The corresponding investigations are performed towards achieving optimized EMSs for efficient power distribution between the drivetrain components. The main outcome of this research addresses improving the fuel consumption while sustaining the State of Charge of the battery for the studied city bus.

The present study proposes an Energy Management Strategy (EMS) control for optimization of fuel consumption in a Hybrid Electric Vehicle (HEV). It addresses an Electrical Variable Transmission (EVT) based HEV and combines an Equivalent Consumption Minimization Strategy (ECMS) to a Rule-based (RB) strategy for such a hybrid system. To this end, the EVT-based vehicle is modeled and integrated into the proposed EMS in the Simulink® environment. The backward-facing model is linked to work with a MATLAB-based genetic algorithm to achieve problem objectives and satisfy constraints at the meantime. Investigation of the results indicates the proposed EMS improves fuel consumption and maintains the battery State of Charge (SoC) considering battery limitations.

While simulating electrical systems it is often important to determine all the current and voltage signals in a 6 switch voltage source inverter. Typically, the inverter model structure depends on the application it has to supply. As a consequence only a limited number of switching state combinations are modeled. Simulation software often offers black box blocks able to handle all switching states. However, such methods often involve iterative solvers because the voltage and current signals affect each other which results in a high computational cost. In this paper, a general model, which considers all possible switching states is introduced. Using this model it is possible to determine all current and voltage signals using only one single matrix inverse regardless of the application and with a reasonable computational effort. Both balanced and unbalanced time dependent load behavior can be considered. The model is validated with measurements on a test setup with an unbalanced load and a brushless DC motor.

This paper investigates the trade-off between efficiency and dynamics of CVT's. Energy efficiently varying the speed ratio of the CVT while maintaining the dynamic requirements is of primordial importance to fully utilize the advantages of the CVT in a drivetrain. Although the toroidal CVT is thoroughly discussed in literature, few articles describe its behavior during ratio variation. Therefore, in this paper a procedure is proposed to achieve optimal ratio variation in terms of settling time and efficiency with a half toroidal CVT. The key concept on which the procedure is based is the expression of the maximum output torque of the CVT. It turns out that the given method offers the fastest possible speed ratio variation for given constraints without excessive increase in slip and thus limited loss in efficiency. The most important constraint proves to be the clamping force which has a profound impact on the resulting dynamics and efficiency of the CVT. The paper indicates that higher clamping forces increase the dynamics of the CVT at a certain cost of loss in efficiency which implies that there is a trade-off between efficiency and dynamics.

This paper discusses the comparison of two series–parallel hybrid electrical vehicles. The first one is based on the Toyota hybrid system, while the second one is equipped with an electrical variable transmission. The problem with previous comparisons between these two transmissions is the lack of validated data used to support the comparison as well as a comprehensive study on the sizing of the electrical variable transmission for a given vehicle and load cycle. To tackle these issues, a validated model of an electrical variable transmission is used in combination with validated scaling laws to assess design changes. This scalable model is used to determine the optimal design and the impact of sizing on the fuel consumption of the vehicle. To exclude the impact of the chosen control methodology, dynamic programming has been used. This technique is not only used to optimize the operating points of the internal combustion engine, but also to find the optimal DC-bus voltage in order to optimize the system level efficiency. The comparison is performed for multiple driving cycles that all show the added value of the electrical variable transmission based hybrid electrical vehicle. On average, over the different driving cycles, a reduction in fuel consumption of 4.75% is achieved while using an electrical variable transmission.

Designing a permanent magnet electrical variable transmission is a cumbersome task, regardless of the considered application. The main reason for this is the iterative design process using a computationally intensive finite element model calculations that is necessary to model its behaviour. This makes it difficult to study or visualize the impact of design changes on, for example, the fuel consumption or cost of a hybrid electrical vehicle. To solve this, electromagnetic scaling laws are used to set up a performance map of the entire system. This map is able to present the performance (i.e. fuel consumption, cost, maximum acceleration, etc.) as a function of an axial and radial scaling factor. The map thus displays the performance of a series of designs which enable the reader to select the optimal one in a graphical way. Furthermore, feasibility constraints such as maximum weight, are added. These constraints allow to reject designs but make it also possible to study the performance as a function of weight or material cost. This is particularly useful for manufacturers as it gives an idea of how their investment is translated into a reduction in fuel consumption.

In this study the dynamic capability of the Electric Variable Transmission (EVT) is presented based on the tracking of a highly dynamic oscillating load. The targeted applications are 3-phase grid connected machines with periodic motions at high frequencies (> 5) Hz, which result in a high alternating to average power ratio (> 5). The overall consumed grid energy is minimized by a high-level non-parametric cascaded control to recuperate the oscillating load energy in a mechanical energy storage component. Here in this paper, this oscillating energy is stored in the inner rotor of the EVT, thereby making EVT an energy storing device in itself. The drivetrain containing an EVT is also shown to have a good load speed tracking performance with the maximum error of +/-1%.

The Electrical Variable Transmission is a complex device of which the electromagnetic behavior is typically studied based on FEM calculations. As the computational effort of these FEM calculations is high, it is a challenging task to investigate the impact of design changes on the performance of the device. To solve this, a Magnetic Equivalent Circuit model is presented. This study shows that the suggested model yields torque values, throughout a major part of the EVT operating range, which are within 10% of torque values obtained via FEM calculations but at a much lower computational effort. As the Magnetic Equivalent Circuit is solely based on known sources, material properties and the parametrized geometry of the EVT, it can, later on, directly be used for design optimization strategies.

Electrical Variable Transmission (EVT), an electromechanical device, can be considered as an alternative solution to the conventional transmission system utilized in Hybrid Electric Vehicles (HEVs). This paper presents a comparison, in terms of fuel consumption of a HEV containing an EVT, a conventional parallel topology and a series topology. To this end, corresponding simulations of these topologies are performed in presence of control strategies enabling battery charge-sustaining and efficient power split. The power flow through the components of the vehicle are attained and fuel consumption results of the considered cases are compared. The investigation of the results indicates suitability of utilizing EVT in HEV configurations with further optimization. The outcome of the current research paves its path for implementation of design optimization approaches on such systems in further research directions.

The use of active car suspensions to maximize driver comfort has been of growing interest in the last decades. Various active car suspension control technologies have been developed. In this work, an optimal control for a full-car electromechanical active suspension is presented. Therefore, a scaled-down lab setup model of this full-car active suspension is established, capable of emulating a car driving over a road surface with a much simpler approach in comparison with a classical full-car setup. A kinematic analysis is performed to assure system behaviour which matches typical full-car dynamics. A state-space model is deducted, in order to accurately simulate the behaviour of a car driving over an actual road pro le, in agreement with the ISO 8608 norm. The active suspension control makes use of a Multiple-Input-Multiple- Output (MIMO) state-feedback controller with proportional and integral actions. The optimal controller tuning parameters are determined using a Genetic Algorithm, with respect to actuator constraints and without the need of any further manual fine-tuning.

The fluctuating behavior of wave energy is a challenge to reach high efficiencies of implemented power take-off (PTO) systems due to the bidirectional movement and high variable loads. The described PTO based on a power sharing transmission (PST) tackles this by converting the bidirectional rotation into a unidirectional rotation of a generator equipped with a flywheel to reduce fluctuation in the output. The generator can then be operated at or close to its optimum efficiency. An auxiliary machine is in charge of the controls. The PST is modeled and implemented in an existing hydrodynamic model of a heaving buoy. A basic control is realised in the simulation resulting in the confirmation of the conversion to a unidirectional rotation and facilitating assessment of the machine efficiencies.

Brushless DC machines (BLDC), Permanent Magnet Synchronous Machines (PMSM), Stepping Motors and Brushed DC machines (BDC) usage is ubiquitous in the power range below 1,5kW. There is a lot of common knowledge on these technologies. Stepping Motors are ideally suited for open loop positioning, BLDC machines are the most obvious candidate for high-speed applications, etc. However, literature lacks comprehensive research comparing these machines over a large range of applications. In this paper, more than 100 motors are considered. Their characteristics are compared and presented in a comprehensive way. These results support the common knowledge concerning the field of application of each technology and new insights follow from this quantitative comparison.

Stepping motor operation is characterized by torque ripples. In this paper it is shown these torque ripples are caused by both the stepping motor drive algorithms and the toothed construction of rotor and stator of the studied hybrid stepping motors. These torque ripples are analyzed, discussed and measured. The torque ripples are measured in the complete operating range of the motor and depicted in this paper for full- half- and micro-stepping. By doing this, the paper provides insight in the vibrating behavior of a stepping motor driven system and possible solutions to overcome this are placed in the right perspective.

In industry, the bulk of the stepping motors is driven in open loop full-step mode with maximum current to avoid step loss. This results in noisy operation due to torque ripples and a poor energy-efficiency. To tackle these problems the current current level at which the stepping motor is driven can be reduced to an optimal level. In this paper, a sensorless load angle controller is proposed and implemented to optimise the drive current level. However, reducing the current level results in a diminished torque margin for load disturbances. In this paper, a countermeasure to enhance the robustness of the sensorless load angle controller against torque disturbances is proposed and assessed trough measurements.

In this paper, a SpectraQuest demonstrator is used to introduce misalignment in a rotating set-up. The vibrations caused by misalignment is measured with both accelerometers on the bearings and eddy current probes on the shaft itself. A comparison is made between the classical spectral analysis, orbitals and full spectra. Orbitals are used to explain the physical interpretation of the vibration caused by misalignment. Full spectra allow to distinguish unbalance from misalignment by looking at the forward and reversed phenomena. This analysis is done for different kinds of misalignment, couplings, excitation forces and combined machinery faults.

This chapter discusses a method to calculate the efficiency of a planetary gearbox with 2 degrees of freedom. Standard measurement procedures in which the efficiency is measured as function of the load torque and input speed become infeasible due to the many possible input output configurations. To solve this, a method is proposed that combines the theory of virtual power and a limited set of measurements. The theory of virtual power is used to link the considered power flow in the device with an expression to calculate the efficiency of the planetary gear in terms of the efficiency of the power path between sun and carrier and carrier and ring. The efficiency of the aforementioned power paths is shown to depend only on the torque applied to these paths which means that speed-dependent losses such as churning losses are negligible. Measurements of the efficiency as function of the torque applied to the sun for a varying speed ratio between ring and carrier are added to validate the approach.

This paper investigates how the efficiency of a Continuously Variable Transmission (CVT) can be visualized in a compact way. At this point there is no standardized method to describe CVT efficiency as there are many inputs which affect the efficiency. Input speed, load torque, speed ratio and clamping force have been identified as dominant factors influencing efficiency. By analyzing the impact of each parameter a method is proposed based on an efficiency map and a scaling law. Efficiency maps are used because they represent the efficiency in the complete operating range and not only in the optimal conditions. The results of this study are of importance for constructors and end users of CVTs. The constructors benefit from the fact that they can plot the efficiency data in a compact format while the end users can use the data to optimize their drivetrain. The approach where efficiency data is used by the end users to optimize the drivetrain in terms of efficiency is called the Extended Product Approach (EPA). By implementing EPA in the design process, large savings on the long term are possible.

BLDC motors are often used for high speed applications, for example in pumps, ventilators and refrigerators. For commutation discrete position information is necessary. This feedback is often provided by Hall sensors instead of more expensive encoders. However, even small misalignment of the Hall sensors in low cost BLDC motors can lead to unwanted torque ripples or reduced performance of BLDC motors. This misplacement leads not only to noise and vibrations caused by the torque ripples but also to lower efficiency. In this paper, a self-sensing technique to assess the misalignment is introduced. The objective is to obtain knowledge of the quality of the commutation by quantifying the misalignment. The method used in this paper is based on the fundamental components of voltage and current measurements and only needs the available current and voltage signals and electrical parameters such as resistance and inductance to estimate the misalignment.