Showing papers on "Synchronous frame published in 2020"

Synchronous-Frame Modeling and dq Current Control of an Unbalanced Nine-Phase Induction Motor Due to Open Phases

Abstract: Multiphase machines have several benefits compared with three-phase machines. Their inherently higher reliability makes them attractive in several applications. For instance, the nine-phase motor can operate with up to six open phases in its stator but with torque ripple production. However, the modeling and control schemes for a balanced motor cannot be used since now the stator is unbalanced. In order to allow the multiphase machine to work magnetically balanced even in open-phase conditions, an adequate dq current control should be employed. To achieve this control scheme, it is necessary to have a synchronous-frame modeling of a nine-phase induction motor under open-phase faults, which is developed here. Using it, a synchronous-frame control is derived, still using proportional controllers in the dq current loops. This is possible due to the use of an appropriate voltage decoupling considering the fault condition. Hence, the unbalanced multiphase induction motor can be controlled very similarly as a balanced one, additionally resulting in the torque ripple minimization. Experimental results characterize the operation with open phases. Simulation and finite-element results show the success of the proposed control scheme.

Novel model predictive direct power control strategy for grid-connected three-level inverters

Abstract: Conventional switching table-based direct power control (DPC) usually suffers from higher power ripples due to the heuristic nature of the switching table. This study presents a novel model predictive DPC (MPDPC) strategy for grid-connected three-level inverters. In the proposed MPDPC strategy, a new synchronous frame-based predictive model is first developed and the conjugate of the complex power is then chosen as the control variable to simplify the analysis. Based on the newly developed predictive model, new principles of the voltage vector selection are further derived with the strict analytical proof to match all the control requirements, including the active and reactive power control, neutral point potential balance control, as well as the avoidance of the high voltage jumps. Finally, experimental results are provided to support the theoretical study and confirm the effectiveness of the proposed MPDPC strategy, as well as to demonstrate better performance in both steady-state and dynamic responses over the conventional DPC.

Control of grid-connected inverter output current: a practical review

Abstract: The number of grid-connected inverters is growing due to the expansion of the use of renewable energies (RE) systems and this may affect grid power quality and stability. Some control algorithms reduce injected current harmonics and add new possibilities to the converter. This paper implements and analyses the proportional integral (PI) controller in the synchronous frame and the proportional resonant (PR) controller with and without the harmonics compensators (HC). All these control strategies have proven to be effective and robust. However, the PR+HC controller presents better output current quality. The PI and PR controllers have similar performances. This work also compares the harmonic content of the current with the IEEE 1547 reference and with three commercial inverters from different manufacturers.

An Optimal Power Control Strategy for Grid-Following Inverters in a Synchronous Frame

Abstract: This work proposes a power control strategy based on the linear quadratic regulator with optimal reference tracking (LQR-ORT) for a three-phase inverter-based generator (IBG) using an LCL filter. The use of an LQR-ORT controller increases robustness margins and reduces the quadratic value of the power error and control inputs during transient response. A model in a synchronous reference frame that integrates power sharing and voltage–current (V–I) dynamics is also proposed. This model allows for analyzing closed-loop eigenvalue location and robustness margins. The proposed controller was compared against a classical droop approach using proportional-resonant controllers for the inner loops. Mathematical analysis and hardware-in-the-loop (HIL) experiments under variations in the LCL filter components demonstrate fulfillment of robustness and performance bounds of the LQR-ORT controller. Experimental results demonstrate accuracy of the proposed model and the effectiveness of the LQR-ORT controller in improving transient response, robustness, and power decoupling.

Adaptive Fuzzy Logic Controller as MPPT Optimization Technique Applied to Grid-Connected PV Systems

Abstract: This chapter presents a complete design of maximum power point tracking control scheme applied to single-phase single-stage and two-stage grid-connected PV systems based on an adaptive fuzzy controller (AFLC). This technique is proposed to enhance the efficiency of a photovoltaic (PV) array and diminish the output power oscillations. The adaptive nature of the proposed controller provides online tuning of fuzzy rules parameters to deal with varying sun radiation and ambient temperature. Ranges of input variables of fuzzy system are defined using genetic algorithm. The adaptive MPPT controller is compared with existing setups, namely the “incremental conductance” (IC) technique and fuzzy logic controller (FLC). The inverter controller is designed in the synchronous frame so that a simplified controller such as PI-controller is implemented. Simulation and experimental results demonstrate the supremacy of the adaptive technique in terms of the speed of tracking and oscillations reduction around the maximum point of power–voltage (P–V) curve.

FCS-MPC and Observer Design in the dq Synchronous Frame: An Experimental Validation

Abstract: The addition of an output LC filter to a voltage source inverter (VSI) allows the generation of high-quality output voltages with reduced harmonic distortion content. For this reason, this topology is widely used for uninterruptible power supply (UPS) applications. To control this system, finite control set model predictive control (FCS-MPC) has been assessed in previous research with promising results. In this paper, the dq-synchronous reference frame (dq-SRF) formulation of FCS-MPC and a state observer for an UPS system are presented and experimentally validated. The advantage of this proposal lies in the simplification of the observer design by considering a deadbeat observer along with the addition of a low-pass filter. In this way, the observer bandwidth is simply determined by the cutoff frequency of the low-pass filter. Simulation and experimental results are compared to assess the performance of the proposed solution.

Discrete-time Direct Pole Placement for Stability Enhancement of LCL-Filtered Inverters in the Synchronous-Reference Frame

Abstract: For LCL-filtered grid-tied inverters, direct pole-placement techniques can combine the fundamental-frequency current regulation and resonance damping simultaneously. As known, for state-space-based direct pole-placement, to purse sensorless operations, state observers have to be employed, which means heavy computation burden and might limit the switching and sampling frequencies. While for transfer-function-based one, the number of necessary variables decreases and meanwhile it saves the computation load from observers. Therefore, the latter is more suitable in practice. Based on this, this paper extends and summarizes this approach for better accessibility, and it shows that, compared to previous applications in the stationary frame, the transfer-function-based discrete-time domain (z-domain) direct pole placement in the synchronous frame presents better robustness against grid impedance variations, improved phase and gain margins, and simplified feed-forward compensation, presuming the cross coupling is ignored. Simulations have verified the analysis and design.

Bdi based pixel for synchronous frame-based & asynchronous event-driven readouts

Abstract: A hybrid frame-based and event driven pixel, the pixel comprising a frame-based capture circuit, an event-driven capture circuit, and a photodiode in electrical communication with both the frame-based and event-driven capture circuits, wherein the frame based capture circuit is a buffered direct injection circuit, and wherein the event-driven capture circuit is a dynamic vision system circuit.

Comparison of Decoupling Techniques via Discrete Luenberger Style Observer for Voltage Oriented Control

Abstract: This work focuses on the implementation, analysis, and comparison of discrete-time synchronous frame current controllers for grid-connected three-phase VSIs using Discrete Luenberger Style Observers (DLSO) in both synchronous (dq), and stationary ( $\alpha\beta$ ) frames including the controller's computational delay compensation. Further, the unique cross-coupling effects of the voltages and currents in the discrete domain are discussed. Pole-zero cancellation techniques are used for the tuning of the current controllers. A discrete Phase-Locked Loop (PLL) with decoupled nonlinearities is proposed. For each topology, Frequency Response Function (FRF) plots and the step responses are obtained and analyzed.

Ctia based pixel for simultaneous synchronous frame-based & asynchronous event-driven readouts

Abstract: A hybrid frame-based and event driven pixel, the pixel comprising a frame-based capture circuit, an event-driven capture circuit, and a photodiode in electrical communication with both the frame-based and event-driven capture circuits, wherein the frame-based capture circuit is a capacitive transimpedance amplifier circuit, and wherein the event-driven capture circuit is a linear asynchronous event representation circuit

Synchronous-frame decoupling current regulators for induction motor control in high-power drive systems: modelling and design

Abstract: In this study, a decoupling current regulator with a simple design approach aiming to mitigate cross-coupling effects during torque or speed disturbance is proposed for induction motor (IM) drives that operate at the low switching frequency. The proposed control method consists to derive a decoupling transfer matrix from the plant accurate model that is inserted at the output of the current controller, while traditional methods consider the feedback synchronous currents or their errors to calculate the compensation terms. The proposed method allows the controlled system to be equivalent to a dual single-input–single-output system without cross-coupling terms. The performances of this method have been validated through simulations and experiments on a 3-kW IM powered by a 3-level neutral-point clamped inverter at different operating conditions. The results show that the proposed decoupling approach provides additional bandwidth frequency than traditional approaches from literature. This characteristic translates into fast response time and improved decoupling dynamics at various operating conditions.

Synchronous Frame Current Estimation Inaccuracies in Permanent Magnet Synchronous Motor Drives

Abstract: Field oriented control of synchronous motor drives involves the closed-loop regulation of current estimates in the synchronously rotating reference frame. The current feedback, obtained through a reference frame transformation that involves the measured position on the measured stationary frame currents, is directly affected by errors in position as well as stationary frame motor current measurements. This paper presents an analytical model of estimated synchronous reference frame currents under simultaneous errors in both current and position sensing, followed by an analysis of the incorrect estimation on the control performance of the motor drive system. The mathematical model is used to study and analyze experimental results on a prototype motor drive system.

SRF Control Algorithm for Five-Level Cascaded H-Bridge D-STATCOM in Single-Phase Distribution System

Abstract: This paper presents a novel method to control a single-phase five-level cascaded H-bridges-based D-STATCOM in distribution system using SRF theory (synchronous frame theory) and inverse park transformation to enhance power quality. Reference current extraction and D-STATCOM gating pulses generation can be done by using SRF theory. To generate quadrature component of current, inverse park transformation is used in proposed method. In the proposed method, reactive power compensation, harmonic elimination, power factor improvement and total harmonic distortion (%THD) are considered as the main objective functions. The proposed technique is investigated through MATLAB. The obtained results are compared with conventional SPWM (Sinusoidal pulse width modulation) control technique.

Control of AC electric machine using average synchronous frame currents

Abstract: A method for controlling an electric machine in a powertrain system in which a driven load is connected to a rotor of the electric machine includes measuring phase currents at a starting point of a sample period using current sensors connected to phase windings of the electric machine. The individual phase currents also are determined at a midpoint of the previous sample period. An angular position of the rotor is determined at the starting point and previous midpoint before calculating synchronous reference frame currents of the electric machine at the starting and previous midpoint using the phase currents and angular position. The method includes calculating average synchronous reference frame currents over the sample period and regulating operation of the electric machine using the average. An electrical system includes the electric machine, a power inverter module, and a controller that executes the method.

1588 synchronization method, system and device for high-speed TTE cascade network

Abstract: The invention belongs to the technical field of network communication. The invention discloses a 1588 synchronization method, a 1588 synchronization system and a 1588 synchronization device for a high-speed TTE cascade network. The 1588 synchronization method comprises steps of enabling a port to calculate link delay; enabling a switching node to receive data frames, stamping receiving timestamps,analyzing the synchronous frame Sync and extracting the frame content; caching timestamp information, calculating time deviation, correcting a local clock, forwarding a synchronization frame Sync toa sending port, sending arbitration, sending analysis and caching a frame type, performing MAC sending processing, taking a sending timestamp, extracting the cached sending frame type, modifying a Sync frame correction domain, and finishing transparent transmission. According to the invention, the data frame type is analyzed at the data link layer and then MAC sending processing is carried out, sothat timestamp correction can be carried out rapidly when a synchronization frame is about to be transmitted to a high-speed network port; and meanwhile, the switching node is designed to adopt a transparent clock and common slave clock working mode, so that the universality and functional diversity of a synchronization scheme are improved.

The Control Method in Synchronous Frame for DVR to Mitigate the Balanced and Unbalanced Voltage Sag/Swells Phenomenon in Power Network

Abstract: Nowadays great attention is paid to the problem of power quality. With the modern equipment, their operation is very sensitive to the quality of the power supply. When the power quality is not guaranteed, such as a nonstandard voltage, current or frequency, which will damage the equipment or the equipment will operate improperly. One of the basic problems here is Sag/Swells voltage. To solve this problem, the dynamic voltage Restorer (DVR) is put into use in the power distribution network. DVR will reduce or add the voltage in series with supply voltage through injection transformer to correct the amplitude, voltage phase and harmonic components into line. This paper proposes a control method for the DVR based on space vector control, with two feedback loops according to voltage and current. The authors use independent control methods, separation of components of direct and reverse in d-q Synchronous Reference Frame for DVR. This method has effectively controlled for the voltage sags and swells phenomenon in balanced and unbalanced. The research results are simulated and verified on Matlab - Simulink software.

Signal processing device and method thereof

Abstract: The present technology relates to a signal processing device and a method thereof that inhibits deterioration in reception sensitivity. In a case where a frequency band is vacant on the basis of a result of carrier sense, a data frame is transmitted as a wireless signal in the frequency band, and further, a synchronous frame formed of predetermined information different from that of the data frame is transmitted as a wireless signal in the frequency band in a case where the data frame is transmitted predetermined number of times within first time. In a case where the synchronous frame is detected, the data frame is detected from a reception signal of predetermined time before the synchronous frame.

A664 synch network design

Abstract: A synchronous computer-controlled communications network is provided that includes an Ethernet network switch; one or more avionics computers communicatively coupled in the synchronous computer-controlled communications network, and one or more end systems communicatively coupled in the synchronous computer-controlled communications network, wherein each of the one or more end systems, wherein the synchronous computer-controlled communications network is synchronized by a synchronization schedule that provides a common start time of a Major Time Frame or the start of a particular partition of the one or more avionics computers based on a user configuration, wherein a first avionics computer of the one or more avionics computers is configured to transmit an Event Synchronous Frame (ESF) to the Ethernet switch, wherein the ESF indicates that the first avionics computer is ready to integrate in a configured synchronous computer-controlled communications network.