EPE Association: EPE 2016 - DS1d: Standard and Advanced Control Techniques for Power Converters

EPE 2016 - DS1d: Standard and Advanced Control Techniques for Power Converters
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2016 ECCE Europe - Conference > EPE 2016 - Topic 03: Measurement and Control > EPE 2016 - DS1d: Standard and Advanced Control Techniques for Power Converters

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   A novel fractional proportional-resonant current controller for Voltage Source Converters
By DANIEL HEREDERO-PERIS [View]
[Download]

Abstract: This paper proposes a hybrid controller that combines conventional proportional-resonant controllerswith the more recent application of fractional order calculus applied to the current control loop of voltagesource converters. The use of existing non-integer orders applied to proportional-integral controllersis extended to resonant controllers. The application of fractional exponents for the integro-derivativeparts contributes with an extra degree of freedom that permits to enhance the obtained response in anextended frequency range when the closed-loop bode diagram is analysed. Different implementationalternatives in the continuous time domain are presented, and the most suitable one is selected. Thenew controller formulation capabilities are compared with conventional proportional-resonant controllersvia simulations and its performance is validated in a test platform based on a 20 kVA silicon-carbideconverter acting as an active filter.

   Control of Parallel Inverters using Nonlinear Oscillators with Virtual Output Impedance
By Antoine ROSSÉ [View]
[Download]

Abstract: Distributed ac power systems using inverters connected in parallel are becoming increasingly widespread with the development of autonomous microgrids. Inverters can be controlled to emulate the dynamics of nonlinear oscillators, such that multiple inverters coupled through an electrical network will synchronize and share load in proportion to their ratings. In this paper, a communication-less control method is developed for islanded parallel inverters based on the Van der Pol oscillator and a virtual impedance technique. The controller can be tuned to guarantee fast synchronization of inverters, as well as optimal load power sharing, regardless of differences in the physical parameters of the inverters and their respective filters. A methodology for parameter selection is presented to tune the controller so that the system voltage amplitude remains within prescribed bounds whilst ensuring optimal load sharing and minimizing synchronization time. Simulation results demonstrate the performances which can be obtained with several parallel-connected inverters using this control method with correctly tuned parameters.

   Control of the Modular Multilevel Converter Motor Drive with Integrated Energy Storage System
By Andrey DUDIN [View]
[Download]

Abstract: A control structure for the modular multilevel converter motor drive with integrated energy storage system (ESS) is described. The control approach uses the ESS to limit the cell capacitor voltages and to avoid circulating currents in the converter at low output frequencies.

   Controller Current-step mode controller to regulate the output voltage of a switching power supply
By Fabio CACCIOTTO [View]
[Download]

Abstract: The article introduces an innovative PWM current-mode technique to control the switched-mode power supplies for regulating the output of the power supply.The proposed technique can be used to control the most common offline power supply topologies andto control any dc-dc converter.Using the new methodology, it is possible to greatly simplify the internal architecture of any integrated IC controller, reducing its complexity and costs and greatly simplifying the overall system's design process.

   Effect of single-current-feedback active damping on the output impedance of grid-connected inverter
By Aapo AAPRO [View]
[Download]

Abstract: LCL-_lter is commonly used as an output-side _lter in a grid-connected converter due to its good attenuation capability at the switching harmonic frequencies. LCL-_lter creates several resonances in theconverter dynamics which shall be damped for ensuring robust performance of the converter. The resonant behavior introduced by the LCL-_lter can be attenuated with active damping (AD) instead of passive damping to improve the conversion ef_ciency. The active damping affects the output impedance of theconverter, and the impedance should be accurately predicted in order to allow analyzing impedance-based stability of power electronics-based power systems. This paper presents the small-signal modelfor inverter-current feedback (ICF) converter using only the inverter-side inductor current feedback forboth control and active damping. Additionally, the output impedance properties are comprehensivelyanalyzed. Experimental measurements from 3-kW prototype are presented to verify the analysis.

   Effect of the loss-minimizing circulating current on the Modular Multilevel Converter with IGBT switches
By Andrey DUDIN [View]
[Download]

Abstract: Time domain optimization is applied to find circulating current to minimize the total power losses of the modular multilevel converter. Total efficiency and design-relevant parameters are analyzed for the operation with and without optimization. Furthermore, first computa-tional effort estimation for two numerical optimization algorithms is presented.

   FPGA-based Implementation of Sorting Networks in MMC applications
By Mattia RICCO [View]
[Download]

Abstract: In this paper an implementation technique for Field Programmable Gate Array (FPGA) devices of two Sorting Networks (SNs) used for control of Modular Multilevel Converter (MMC) is presented. In such applications, the classical sorting algorithms are based on repetitive/recursive loops, and they are usually implemented in microcontrollers or DSPs. However, they are not convenient for hardware implementation due to their inherent sequential operation. Instead, the proposed SNs, are suitable for FPGA devices thanks to their fixed parallel structure that allows improving the timing performance of the capacitor voltage balancing algorithm. The advantages and the main challenges of the Bitonic SN and Even-Odd SN in MMC applications are discussed. Moreover, in order to pre-evaluate the required resources and the execution time, equations are derived for both the proposed SNs and then a comparison is performed between them. The proposed equations are validated by comparing the real required resources with the estimated ones by using the Xilinx Vivado Design Suite tool. Finally, the operation of the proposed Bitonic SN is also tested in Vivado Simulator, achieving the sorted list of 8 elements in 18 clock cycles as expected.

   Grid Impedance Estimation in Inductive-Resistive Distributed Power Networks Using Particle Filtering
By Rene DIETZ [View]
[Download]

Abstract: This paper proposes a grid impedance estimation method for distributed generation units using a sequen- tial Monte Carlo method called particle _ltering. The theoretical background of this method is reviewed, and system equations are derived. First results for implementation are given in this course of the paper. To the authors' knowledge, this is the _rst implementation of this _lter in grid impedance estimation.

   Improved EPLL Performance Using Multiple Sinusoidal Signal Integrators for Grid-Connected VSC System Synchronisation
By Osazee IDEHEN [View]
[Download]

Abstract: This paper presents a novel synchronisation technique, which is based on the structural modification of the conventional Enhanced Phase-Locked Loop (EPLL) by introducing Multiple Sinusoidal Signal Integrator (MSSI) modules. The proposed MSSI-EPLL proves to overcome the weakness of the EPLL by employing adaptive MSSI modules in both amplitude and frequency loops to effectively eliminate low order harmonics under distorted AC grid condition, without sacrificing the dynamic performance. The test bench setup also considers the application of a single-to-ground fault at the Point of Common Coupling (PCC) and a step change in AC system frequency. For these test scenarios, the EPLL suffers noticeable periodic ripples during the dynamic process due to phase and amplitude jumps, with slower response time and steady oscillations during frequency change. But, these drawbacks are significantly mitigated by the MSSI-EPLL, as proven mathematically and confirmed through simulation studies.

   Loss reduction in a 3L-NPC inverter with SiC neutral point diodes through model predictive control
By Felipe FILSECKER [View]
[Download]

Abstract: The use of a model predictive control algorithm to reduce the losses in a 3L-NPC inverter with SiCneutral point diodes was investigated. It considers the reduced switching losses associated with thecommutations that involve a SiC diode. A loss reduction of 5\% is achieved compared to a standardsine-triangle modulation.

   Model Predictive Control Strategy for Multi-Phase Thyristor Matrix Converters - Advantages, Problems and Solutions
By Michael LEUER [View]
[Download]

Abstract: A 27-to-3-phase thyristor matrix converter using a model predictive control (MPC) is considered. Comparedto the standard method theMPC considers the coupled overall system. Due to this, all 27^3 =19683switching states are to be considered. The result of the MPC strategy is, compared to classical control, adrastic reduction of the commutation frequency and respectively the converter losses. However, besidesthe advantages there are still some problems with the use ofMPC for thyristor matrix converter. Thereforthis contribution presents extensions of the standard direct model predictive control strategy to overcomethese problems. The result is a predictive control structure with a fallback level for problematic workingareas. By this, a low total harmonic distortion (THD) as well as a high efficiency can be achieved.

   Model Predictive Power Control based on Virtual Flux for Grid connected Three-level Neutral-Point Clamped Inverter
By Van Quang Binh NGO [View]
[Download]

Abstract: The paper presents a detailed description of the prediction model for Predictive Power Control based on Virtual Flux (MPPC-VF) scheme for control grid connected three-level neutral-point clamped inverter (3L-NPC). The controller uses a model to calculate predictions of the future values of the virtual flux, grid currents and DC-link capacitor voltages for all possible voltage vectors. The active and reactive power can be estimated based on the virtual flux and the current. The cost function is defined to minimize the error between the active, reactive power and their references, balance the DC-link capacitor voltage and reduce the switching frequency. The optimal switching state that minimizes the cost function is selected and applied to the inverter. Simulation results under different conditions are presented and compared with conventional Direct Power Control and Space Vector Modulation (DPC-SVM). The obtained results show the better performances of the proposed control method.

   Optimization of direct current controlled multilevel inverters under distorted conditions
By Martin HOFMANN [View]
[Download]

Abstract: Current controlled inverters need to be dynamic and robust even under grid disturbances and differentgrid faults. Besides a robust control method the requirements for synchronization of the system becomemore and more important especially when multilevel inverter topologies are used. The combination ofdirect current control methods and advanced grid synchronization techniques promise excellent workingbehavior even under abnormal conditions within the hardware and control system.

   Phase-shift PWM for Three-phase Voltage Source Converters
By Dong JIANG [View]
[Download]

Abstract: This paper give a overall study of phase-shift PWM in three-phase voltage source converters. Bychanging the phase-shift of carrier waves, the pulse locations will be changed and impact the system performance.This paper gives a tool to study and predict phase-shift PWM's effect: calculating the six rising and falling edges ofthe phase voltage in each switching cycle and deriving the voltage and current in each sector. With this tool, theimpact of phase-shift PWM on current ripple and EMI has been studied. Phase-shift could be designed with theprediction tool to improve current ripple and EMI of the converter system. Simulation and experimental results areprovided to support the study.

   Robust Control of Extended Commutation Cell Based Converters
By Erik LEMMEN [View]
[Download]

Abstract: An extended commutation cell (ECC) is a four-port four-switch power processing cell that allows for bidirectional energy transport in two orthogonal directions throughout the structure. By cascading multiple cells a high-quality output voltage waveform can be constructed with a high number of levels. In this paper a model of the internal energy flow, together with a robust control structure is proposed. The proposed structure is analyzed, simulated and experimentally verified on an eight-level inverter prototype of 4.4 kW.

   Two-Dimension Sorting and Selection Algorithm featuring Thermal Balancing Control for Modular Multilevel Converters
By Ariya SANGWONGWANICH [View]
[Download]

Abstract: With the aim to solve the unbalanced thermal behavior in the modular multilevel converter, introduced by mismatch in the submodule parameters, a thermal balancing control strategy is proposed here. The proposed solution ensures a balanced junction temperature for the power devices, while the balance between the capacitor voltages is maintained.

EPE 2016 - DS1d: Standard and Advanced Control Techniques for Power Converters
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2016 ECCE Europe - Conference > EPE 2016 - Topic 03: Measurement and Control > EPE 2016 - DS1d: Standard and Advanced Control Techniques for Power Converters
	[return to parent folder]

	A novel fractional proportional-resonant current controller for Voltage Source Converters By DANIEL HEREDERO-PERIS	[View] [Download]
Abstract: This paper proposes a hybrid controller that combines conventional proportional-resonant controllerswith the more recent application of fractional order calculus applied to the current control loop of voltagesource converters. The use of existing non-integer orders applied to proportional-integral controllersis extended to resonant controllers. The application of fractional exponents for the integro-derivativeparts contributes with an extra degree of freedom that permits to enhance the obtained response in anextended frequency range when the closed-loop bode diagram is analysed. Different implementationalternatives in the continuous time domain are presented, and the most suitable one is selected. Thenew controller formulation capabilities are compared with conventional proportional-resonant controllersvia simulations and its performance is validated in a test platform based on a 20 kVA silicon-carbideconverter acting as an active filter.

	Control of Parallel Inverters using Nonlinear Oscillators with Virtual Output Impedance By Antoine ROSSÉ	[View] [Download]
Abstract: Distributed ac power systems using inverters connected in parallel are becoming increasingly widespread with the development of autonomous microgrids. Inverters can be controlled to emulate the dynamics of nonlinear oscillators, such that multiple inverters coupled through an electrical network will synchronize and share load in proportion to their ratings. In this paper, a communication-less control method is developed for islanded parallel inverters based on the Van der Pol oscillator and a virtual impedance technique. The controller can be tuned to guarantee fast synchronization of inverters, as well as optimal load power sharing, regardless of differences in the physical parameters of the inverters and their respective filters. A methodology for parameter selection is presented to tune the controller so that the system voltage amplitude remains within prescribed bounds whilst ensuring optimal load sharing and minimizing synchronization time. Simulation results demonstrate the performances which can be obtained with several parallel-connected inverters using this control method with correctly tuned parameters.

	Control of the Modular Multilevel Converter Motor Drive with Integrated Energy Storage System By Andrey DUDIN	[View] [Download]
Abstract: A control structure for the modular multilevel converter motor drive with integrated energy storage system (ESS) is described. The control approach uses the ESS to limit the cell capacitor voltages and to avoid circulating currents in the converter at low output frequencies.

	Controller Current-step mode controller to regulate the output voltage of a switching power supply By Fabio CACCIOTTO	[View] [Download]
Abstract: The article introduces an innovative PWM current-mode technique to control the switched-mode power supplies for regulating the output of the power supply.The proposed technique can be used to control the most common offline power supply topologies andto control any dc-dc converter.Using the new methodology, it is possible to greatly simplify the internal architecture of any integrated IC controller, reducing its complexity and costs and greatly simplifying the overall system's design process.

	Effect of single-current-feedback active damping on the output impedance of grid-connected inverter By Aapo AAPRO	[View] [Download]
Abstract: LCL-_lter is commonly used as an output-side _lter in a grid-connected converter due to its good attenuation capability at the switching harmonic frequencies. LCL-_lter creates several resonances in theconverter dynamics which shall be damped for ensuring robust performance of the converter. The resonant behavior introduced by the LCL-_lter can be attenuated with active damping (AD) instead of passive damping to improve the conversion ef_ciency. The active damping affects the output impedance of theconverter, and the impedance should be accurately predicted in order to allow analyzing impedance-based stability of power electronics-based power systems. This paper presents the small-signal modelfor inverter-current feedback (ICF) converter using only the inverter-side inductor current feedback forboth control and active damping. Additionally, the output impedance properties are comprehensivelyanalyzed. Experimental measurements from 3-kW prototype are presented to verify the analysis.

	Effect of the loss-minimizing circulating current on the Modular Multilevel Converter with IGBT switches By Andrey DUDIN	[View] [Download]
Abstract: Time domain optimization is applied to find circulating current to minimize the total power losses of the modular multilevel converter. Total efficiency and design-relevant parameters are analyzed for the operation with and without optimization. Furthermore, first computa-tional effort estimation for two numerical optimization algorithms is presented.

	FPGA-based Implementation of Sorting Networks in MMC applications By Mattia RICCO	[View] [Download]
Abstract: In this paper an implementation technique for Field Programmable Gate Array (FPGA) devices of two Sorting Networks (SNs) used for control of Modular Multilevel Converter (MMC) is presented. In such applications, the classical sorting algorithms are based on repetitive/recursive loops, and they are usually implemented in microcontrollers or DSPs. However, they are not convenient for hardware implementation due to their inherent sequential operation. Instead, the proposed SNs, are suitable for FPGA devices thanks to their fixed parallel structure that allows improving the timing performance of the capacitor voltage balancing algorithm. The advantages and the main challenges of the Bitonic SN and Even-Odd SN in MMC applications are discussed. Moreover, in order to pre-evaluate the required resources and the execution time, equations are derived for both the proposed SNs and then a comparison is performed between them. The proposed equations are validated by comparing the real required resources with the estimated ones by using the Xilinx Vivado Design Suite tool. Finally, the operation of the proposed Bitonic SN is also tested in Vivado Simulator, achieving the sorted list of 8 elements in 18 clock cycles as expected.

	Grid Impedance Estimation in Inductive-Resistive Distributed Power Networks Using Particle Filtering By Rene DIETZ	[View] [Download]
Abstract: This paper proposes a grid impedance estimation method for distributed generation units using a sequen- tial Monte Carlo method called particle _ltering. The theoretical background of this method is reviewed, and system equations are derived. First results for implementation are given in this course of the paper. To the authors' knowledge, this is the _rst implementation of this _lter in grid impedance estimation.

	Improved EPLL Performance Using Multiple Sinusoidal Signal Integrators for Grid-Connected VSC System Synchronisation By Osazee IDEHEN	[View] [Download]
Abstract: This paper presents a novel synchronisation technique, which is based on the structural modification of the conventional Enhanced Phase-Locked Loop (EPLL) by introducing Multiple Sinusoidal Signal Integrator (MSSI) modules. The proposed MSSI-EPLL proves to overcome the weakness of the EPLL by employing adaptive MSSI modules in both amplitude and frequency loops to effectively eliminate low order harmonics under distorted AC grid condition, without sacrificing the dynamic performance. The test bench setup also considers the application of a single-to-ground fault at the Point of Common Coupling (PCC) and a step change in AC system frequency. For these test scenarios, the EPLL suffers noticeable periodic ripples during the dynamic process due to phase and amplitude jumps, with slower response time and steady oscillations during frequency change. But, these drawbacks are significantly mitigated by the MSSI-EPLL, as proven mathematically and confirmed through simulation studies.

	Loss reduction in a 3L-NPC inverter with SiC neutral point diodes through model predictive control By Felipe FILSECKER	[View] [Download]
Abstract: The use of a model predictive control algorithm to reduce the losses in a 3L-NPC inverter with SiCneutral point diodes was investigated. It considers the reduced switching losses associated with thecommutations that involve a SiC diode. A loss reduction of 5\% is achieved compared to a standardsine-triangle modulation.

	Model Predictive Control Strategy for Multi-Phase Thyristor Matrix Converters - Advantages, Problems and Solutions By Michael LEUER	[View] [Download]
Abstract: A 27-to-3-phase thyristor matrix converter using a model predictive control (MPC) is considered. Comparedto the standard method theMPC considers the coupled overall system. Due to this, all 27^3 =19683switching states are to be considered. The result of the MPC strategy is, compared to classical control, adrastic reduction of the commutation frequency and respectively the converter losses. However, besidesthe advantages there are still some problems with the use ofMPC for thyristor matrix converter. Thereforthis contribution presents extensions of the standard direct model predictive control strategy to overcomethese problems. The result is a predictive control structure with a fallback level for problematic workingareas. By this, a low total harmonic distortion (THD) as well as a high efficiency can be achieved.

	Model Predictive Power Control based on Virtual Flux for Grid connected Three-level Neutral-Point Clamped Inverter By Van Quang Binh NGO	[View] [Download]
Abstract: The paper presents a detailed description of the prediction model for Predictive Power Control based on Virtual Flux (MPPC-VF) scheme for control grid connected three-level neutral-point clamped inverter (3L-NPC). The controller uses a model to calculate predictions of the future values of the virtual flux, grid currents and DC-link capacitor voltages for all possible voltage vectors. The active and reactive power can be estimated based on the virtual flux and the current. The cost function is defined to minimize the error between the active, reactive power and their references, balance the DC-link capacitor voltage and reduce the switching frequency. The optimal switching state that minimizes the cost function is selected and applied to the inverter. Simulation results under different conditions are presented and compared with conventional Direct Power Control and Space Vector Modulation (DPC-SVM). The obtained results show the better performances of the proposed control method.

	Optimization of direct current controlled multilevel inverters under distorted conditions By Martin HOFMANN	[View] [Download]
Abstract: Current controlled inverters need to be dynamic and robust even under grid disturbances and differentgrid faults. Besides a robust control method the requirements for synchronization of the system becomemore and more important especially when multilevel inverter topologies are used. The combination ofdirect current control methods and advanced grid synchronization techniques promise excellent workingbehavior even under abnormal conditions within the hardware and control system.

	Phase-shift PWM for Three-phase Voltage Source Converters By Dong JIANG	[View] [Download]
Abstract: This paper give a overall study of phase-shift PWM in three-phase voltage source converters. Bychanging the phase-shift of carrier waves, the pulse locations will be changed and impact the system performance.This paper gives a tool to study and predict phase-shift PWM's effect: calculating the six rising and falling edges ofthe phase voltage in each switching cycle and deriving the voltage and current in each sector. With this tool, theimpact of phase-shift PWM on current ripple and EMI has been studied. Phase-shift could be designed with theprediction tool to improve current ripple and EMI of the converter system. Simulation and experimental results areprovided to support the study.

	Robust Control of Extended Commutation Cell Based Converters By Erik LEMMEN	[View] [Download]
Abstract: An extended commutation cell (ECC) is a four-port four-switch power processing cell that allows for bidirectional energy transport in two orthogonal directions throughout the structure. By cascading multiple cells a high-quality output voltage waveform can be constructed with a high number of levels. In this paper a model of the internal energy flow, together with a robust control structure is proposed. The proposed structure is analyzed, simulated and experimentally verified on an eight-level inverter prototype of 4.4 kW.

	Two-Dimension Sorting and Selection Algorithm featuring Thermal Balancing Control for Modular Multilevel Converters By Ariya SANGWONGWANICH	[View] [Download]
Abstract: With the aim to solve the unbalanced thermal behavior in the modular multilevel converter, introduced by mismatch in the submodule parameters, a thermal balancing control strategy is proposed here. The proposed solution ensures a balanced junction temperature for the power devices, while the balance between the capacitor voltages is maintained.