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In this paper a control scheme for a PMSM drive that keeps the torque ripple within predefined limits is presented. The electromagnetic torque is assumed to be proportional to i1q, which is measured by using Sigma-Delta Analog to Digital Converters (ΣΔ-ADCs) with a very high sampling rate, so the actual ripple of the torque can be obtained and controlled in an enhanced way. The measurement results...
The present paper deals with the sensorless harmonic speed control of a drive for repetitive mechanical systems and proposes a harmonic control scheme, in which a proportional-integral controller is dedicated to each single harmonic component of the speed error. In addition, the harmonic speed controller provides information that can be used for the estimation of the load torque and for a diagnostic...
This paper describes a novel sensorless identification method for mechanical two-mass-systems and the influence of varying parameters and operation conditions on its performance. The identification procedure is carried out during the encoderless control of the drive system and based on the frequency response measurement of the mechanical setup. An extended speed adaptive observer structure serves...
This paper presents a reduced-order generalized average model for a grid-connected High-Frequency-link micro-inverter for renewable energy sources applications; the grid-connected topology is based on the DC/DC Dual-Active-Bridge (DAB) converter without the intermediate DC-link. The switched model for the system is presented and from it the reduced-order generalized average model is obtained. Harmonic...
The control of any AC-machine demands the rotor or a flux position to describe the machine. The use of an encoder to solve this problem is possible but this reduces the total reliability of the drive. Encoderless methods can identify the required position by only evaluating the measured electrical quantities of the machine. Generally, additional test signals need to be injected into the machine in...
This paper deals with a new diagnostic method to detect bearing faults in repetitive mechanical systems based on a Fourier series representation of the load torque. A laboratory setup with a horizontal slider-crank mechanism was built as an example of such a system. The load torque in the examined system is estimated and characterized by a periodic function of the crank angle. The difference between...
In this paper a predictive control for a PMSM (Permanent Magnet Synchronous Machine) with variable switching frequency and torque ripple control is presented. The control strategy takes advantage of the parallel processing capabilities and the possibility to customize peripherals in the FPGA. As special feature an online adaptable space vector pulse width modulator that can be used for the reconfiguration...
In the past, plenty of identification methods have been proposed for the encoderless control of induction machines and of permanent magnet synchronous machines, including all important tasks of the encoderless operation, such as the identification of the initial rotor position, the low and the high speed operation of the drive. However, not all the available methods are suitable for the application...
The redundant states in the output voltages of a Three-level Neutral Point Clamped Voltage Source Inverter (3L-NPC VSI) can be used to control the neutral point or to reduce the common mode voltage. However, the use of the redundant states to redistribute the losses among the switching devices of 3L-NPC VSI is a further possibility that was reported in previous papers. The proposed method for active...
In this paper a FPGA control platform suitable for the implementation of a model based predictive control of the PMSM (Permanent Magnet Synchronous Machine) with variable switching frequency is presented. The control strategy takes advantage of the parallel processing capabilities and of the possibility to customize peripherals otherwise impossible by using conventional microcontrollers. A special...
This paper presents a single-phase HF-link microinverter for low-power PV applications with a simple instantaneous power modulation scheme; the topology is based on the DC/DC Dual-Active-Bridge (DAB) converter without the intermediate DC-link, which reduces the number of power processing stages. The modulation scheme is simple, and it can be implemented with low-computational effort in low-complexity...
The switches of multilevel inverters in high-power applications are mounted on dedicated heatsinks and there is no heat sharing among the devices. If one semiconductor device is exposed to excessive thermal stress, then the lifespan of the affected device is reduced significantly. This thermal overload may arise due to degradation of the cooling system, failures in firing or in the drivers, inappropriate...
It is well-known that in the area of encoderless control methods for AC-drives a single approach is not capable to cover all speed ranges and all types of machines. Therefore, a combination of several methods is necessary. Especially in the case of electrically excited synchronous machines, the methods proposed for the low speed region and for the detection of the initial rotor position fail for many...
In this paper, a novel 42 slot, 20 pole ironless winding for use in an axial-flux machine is presented. The proposed design improves the utilization of the available air gap area and is based on the implementation of the winding as a printed circuit board (PCB). Besides, it is compared with a conventional 21 slot, 20 pole ironless axial-flux winding regarding the criteria: torque generation and induced...
The present paper analyzes the reduction of the double frequent power pulsations in the DC-link of a single phase ZSI by using a passive resonant circuit. Three possible and effective topologies for the resonant circuit have been examined. The advantages and disadvantages of the three versions have been discussed in this paper and validated by measurements on a laboratory set-up.
For high power applications, in which the discrete power switches are mounted on separate heatsinks, an overload of a semiconductor device leads to a local excessive thermal stress and eventually to a failure of the system. Despite of several control strategies that ensure the even distribution of losses in the normal operation, a local thermal overload can arise due to degradation of the cooling...
This paper deals with the analytical calculation of torque in PM machines with surface mounted magnets. The calculation is based on the cross-correlation of stator and rotor flux density. As a consequence of the Parseval's theorem, the magnetic cross-energy, given by a space-dependent function, is equal to the sum of the components of the spectral energy density in the frequency domain. By using the...
In this paper a predictive control for a permanent magnet synchronous machine with LC-Filter aiming sinusoidal voltage at the machine terminals is presented. The proposed scheme assumes a virtual multilevel inverter and utilizes a conventional pulse width modulator (PWM). A first estimation of the voltage space phasor that has to be synthesized by the inverter is computed by using the equations of...
In the following paper, an analytical approach for the calculation of the the induced emf in windings of electrical machines is provided. This method uses the complex Fourier series that describe the stator winding function and the magnetic flux density distribution in the air gap that is caused by the rotor permanent magnets. By using a special case of the Parseval's theorem, the induced emf can...
The objective of this paper is the implementation of a three phase 5-level cascaded H-bridge inverter connected to the grid. A voltage oriented control (VOC) based on space vector pulse width modulation technique (SV-PWM) is used for the control of the converter by using only a single DSP. A feedforward modulation index compensation is applied to overcome the problem of voltage imbalance among the...
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