FPGA-based Real-time Simulator Research Articles

A Network Analysis Modeling Method of the Power Electronic Converter for Hardware-in-the-Loop Application

The application of field-programmable gate array (FPGA) in the hardware-in-the-loop simulation (HiLs) has enabled the time step reaching the range of hundreds of nanoseconds. However, the time performance of FPGA-based real-time simulation remains to be improved. In this article, a network analysis modeling method for FPGA-based real-time simulation of the power electronic converter is proposed. An ideal switching network unit, without requiring a large amount of memory, is used to determine the topology of the circuit and solve interface voltages/currents from the torn circuit. A parallel integration method is then implemented to obtain the status of the circuit element. At last, a diode-clamped three-level voltage source converter is used as a case study to demonstrate the effectiveness of the method. A 40-ns simulation step is finally achieved on the National Instruments (NI) FlexRIO PXIe-7975 platform. The accuracy of the proposed method is also verified against the results from MATLAB/Simulink.

A Universal Design of FPGA-Based Real-Time Simulator for Active Distribution Networks Based on Reconfigurable Computing

Reconfigurable computing is that the logical resources in the system can be reconfigured according to the real-time changing data flow to achieve different calculation functions. The reconfigurable computing system has both high efficiency on hardware and universality of software. The field programmable gate array (FPGA)-based real-time simulator for active distribution networks (ADNs) requires a long compilation time for case modification, with low efficiency and low versatility, making it inconvenient and difficult for users. To solve the problem of long compile time with a new case, a universal design of the FPGA-based real-time simulator for ADNs based on reconfigurable computing is proposed in this paper. It includes the universal design of the simulation parameter configuration, the simulation initial value setting, the linear equations solving module and the simulation result output module. The proposed universal design of the simulator makes the modification and change of the cases and parameters without recompiling and further improves the simulation efficiency. Simulation results are conducted and compared with PSCAD/EMTDC to validate the correctness and effectiveness of the universal design.

Design and development of FPGA-based real-time RF cavity simulator using LabVIEW

ABSTRACT To understand the behaviour of RF (Radio Frequency) cavity in different machine operating conditions and to optimise the low-level radio frequency systems, FPGA (Field Programmable Gate Array)-based real-time RF cavity simulator is presented in this paper. LabVIEW is used for programming of FPGA to make this simulator user-friendly. For the implementation of the RF cavity, a suitable transfer function is derived in a continuous domain. By using bilinear transformation technique, this transfer function is discretised for implementation on FPGA. A Simulink model for this RF cavity is also implemented for verification of results. Here, Indus-2 RF cavity parameters are considered and fill time of cavity took a comparison factor.

FPGA-Based Real-Time Simulation of High-Power Electronic System With Nonlinear IGBT Characteristics

The hardware-in-the-loop simulation plays a vital role in the test of high-power electronic system. Although the application of field-programmable gate array (FPGA) embedded system has enabled the real-time system simulating below 500 ns, the transient characteristic of high-voltage insulated-gate bipolar transistor (HVIGBT) is largely compromised. In this paper, a new piecewise HVIGBT model, considering its driver circuit effect and parasite parameter, is proposed for FPGA-based real-time simulation applications. With the attempt to reduce the simulation latency, we propose an FPGA solver with a parallel structural to divide the system into several layers. The model could not only provide accurate system-level performance of the power electronic converter but also give an insight into the transient behavior effect of high-power electronic system. Finally, a case study about emulation of traction system of high-speed train is also presented. Implementations are made on an FPGA Kintex-7 embedded in National Instruments FlexRIO PXIe-7975. The obtained results show that the proposed modeling algorithm can achieve both accuracy and efficiency within a fixed real-time simulation time step of 25 ns.

A new approach for FPGA-based real-time simulation of power electronic system with no simulation latency in subsystem partitioning

In real-time Hardware-in-the-Loop (HIL) test applications for power electronic systems, the main hurdle is to tackle with the mathematical models of variable topology of complex and high frequency driven converter. The most widespread solution is to separate the whole system into subsystems. However, partitioning method usually introduces simulation time step latency between different subsystems, which causes numeric instabilities especially when stiff situation occurs. In this paper, we propose a novel parallel simulation approach which has no time step latency in the whole system division, from which a numerically stable system modeling can be realized. Its numerical accuracy of the solution, the architecture design, and the issue pertaining to the parallel calculation are discussed in detail in this paper. The pertinence of the developed solution is also tested using a case study relating to a traction system power electronic application. For this case study, implementations are made both on a 3 GHz Xeon CPU of RT LAB real-time simulator with a 2 μs simulation step and a Field Programmable Gate Arrays (FPGA) Kintex-7 embedded in National Instruments FlexRIO PXIe-7975 enabling a simulation step below 50 ns. Besides, comparison with results obtained from Simpower system in Matlab allows to evaluate the accuracy of our proposed modeling approach.

Kernel Solver Design of FPGA-Based Real-Time Simulator for Active Distribution Networks

The field-programmable gate array (FPGA)-based real-time simulator takes advantage of many merits of FPGA, such as small time-step, high simulation precision, rich I/O interface resources, and low cost. The sparse linear equations formed by the node conductance matrix need to be solved repeatedly within each time-step, which introduces great challenges to the performance of the real-time simulator. In this paper, a fine-grained solver of the FPGA-based real-time simulator for active distribution networks is designed to meet the computational demand. The framework of the solver, offline process design on PC and online process design on FPGA are proposed in detail. The modified IEEE 33-node system with photovoltaics is simulated on a 4-FPGA-based real-time simulator. Simulation results are compared with PSCAD/EMTDC under the same conditions to validate the solver design.

An automated FPGA real-time simulator for power electronics and power systems electromagnetic transient applications

The paper presents an automated FPGA-based real-time electromagnetic transients simulator for power electronics and power systems applications. The simulator features an automated procedure enabling its straightforward applications to different topologies by avoiding the need of complex FPGA programming. The proposed solver integrates: (i) the Modified Augmented Nodal Analysis (MANA) method, (ii) the Fixed Admittance Matrix Nodal Method (FAMNM), (iii) the optimal selection of the switch conductance parameter, and (iv) efficient sparse matrix-to-vector multiplier. The simulator is able to accurately reproduce, in real-time, electromagnetic transients taking place in power electronics devices together with electromagnetic waves propagating in transmission lines. The peculiar structure of the MANA-FAMNM solver enables to reach extremely low integration time steps and avoids the need to redesign the FPGA code. The results of the proposed simulator are validated by dedicated comparisons with off-line EMTP-RV simulations and a hardware-in-the-loop (HIL) test for a three-phase two-level inverter and a three-phase power network.

Design and Implementation of an FPGA-based Real-time Simulator for a Dual Three-Phase Induction Motor Drive

This paper presents a digital hardware implementation of a real-time simulator for a multiphase drive using a field-programmable gate array (FPGA) device. The simulator was developed with a modular and hierarchical design using very high-speed integrated circuit hardware description language (VHDL). Hence, this simulator is flexible and portable. A state-space representation model suitable for FPGA implementations was proposed for a dual three-phase induction machine (DTPIM). The simulator also models a two-level 12-pulse insulated-gate bipolar transistor (IGBT)-based voltage-source converter (VSC), a pulse-width modulation scheme, and a measurement system. Real-time simulation outputs (stator currents and rotor speed) were validated under steady-state and transient conditions using as reference an experimental test bench based on a DTPIM with 15 kW-rated power. The accuracy of the proposed digital hardware implementation was evaluated according to the simulation and experimental results. Finally, statistical performance parameters were provided to analyze the efficiency of the proposed DTPIM hardware implementation method.

FPGA-based real time simulation and control of grid-connected photovoltaic systems

Nowadays, FPGA devices are widely used to build control platforms in various fields of real time applications such as wireless telecommunications, image and signal processing, robotics and renewable energy systems. In grid-connected photovoltaic (PV) systems, an effective control strategy is needed for an efficiently use of solar energy as well as for energy supplies optimization. This paper presents an investigation, modelling and FPGA based digital controller design of a two-stage grid connected photovoltaic (GCPV) system. The basic idea of the proposed control structure is to operate the PV system as an active power generator and reactive power regulator. Firstly, a comprehensive study of dynamic behaviour of a two-stage GCPV system using Matlab/Simulink was presented. Subsequently, a digital circuit design of Incremental Conductance (IncCond) algorithm and decoupled active–reactive power control algorithm is carried out using the Hardware Description Language (VHDL). The simulation results confirm the accuracy of the adopted control strategy as well as the feasibility of the overall FPGA based control circuit.

An FPGA-based real-time UAV SAR raw signal simulator

An FPGA-based real-time UAV SAR raw signal simulator

A State-Space Modeling Approach for the FPGA-Based Real-Time Simulation of High Switching Frequency Power Converters

A comprehensive approach to the real-time simulation of power converters using a state-space representation is covered in this paper. Systematic formulations of state-space equations as well as a new switch model are presented. The proposed switch model exhibits a natural switching behavior, which is a valuable characteristic for the real-time simulation of power converters, thereby allowing individual treatment of switching devices irrespective of the converter topology. Successful implementations of the proposed switch model on a field programmable gate array (FPGA) device are reported, with two alternative approaches: 1) precomputing network equations for all switch state combinations and 2) solving network equations on-chip using the Gauss-Seidel iterative method. A two-level three-phase voltage source converter is implemented using the first approach, with a time step of 80 ns and a switching frequency of 200 kHz. Ideal and nonideal boost converters are also implemented on FPGA using the second approach, with a time step of 75 ns and a switching frequency of 20 kHz. Comparison with SPICE models shows that the proposed switch model offers very satisfactory accuracy and precision.

Comparison of insulated gate bipolar transistor models for FPGA-based real-time simulation of electric drives and application guideline

In this study, a comparison of various insulated gate bipolar transistor (IGBT) models for field-programmable gate array (FPGA)-based real-time simulation of power electronic devices is presented. System-level behavioural models include ideal, switching function and averaged models, and the detailed device-level model includes both linear behavioural and non-linear look-up table-based models of IGBT. A three-level 12-pulse voltage source converter system driving a squirrel-cage induction motor has been chosen as the test case system. The entire system including the controller and pulse width modulation (PWM) is implemented on a single FPGA using very high-speed description language in real-time at a fixed time-step of 12.5 ns. The Altera Startix III FPGA is the device used for real-time simulation. Results obtained through all five models are compared and as expected, it has been found that the behaviour-mode simulation is fast but comes with a sacrifice of accuracy and details. A guideline is provided for the users with suggestions, so that the right kind of model can be selected for a particular study.

Comparison of insulated gate bipolar transistor models for FPGA-based real-time simulation of electric drives and application guideline

Comparison of insulated gate bipolar transistor models for FPGA-based real-time simulation of electric drives and application guideline

Massively Parallel Implementation of AC Machine Models for FPGA-Based Real-Time Simulation of Electromagnetic Transients

This paper presents a generalized, parallel implementation methodology for real-time simulation of ac machine transients in an FPGA-based real-time simulator. The proposed method adopts nanosecond range simulation time-step and exploits the large response time of a rotating machine to: 1) eliminate the need for predictive-corrective action for the machine electrical and mechanical variables, 2) decouple the solution of the dq0 stator currents, and 3) enable the use of one-time-step delayed interface between the machine and the rest of the system which decouples the machine solution from that of the rest of the system. The proposed method simplifies the solution of the machine model without compromising accuracy or numerical stability of the simulation. This paper also presents a massively parallel, customized hardware architecture tailored to the solution of the mathematical model of ac machines. The proposed method and the developed hardware architecture are tested and verified based on the implementation of a permanent-magnet synchronous machine model and an induction machine-based ac-drive system in a field-programmable gate-array-based simulator. Real-time simulation is achieved with a computation time of 44 ns within the simulation timestep.

Real-time digital simulation of power electronics systems with Neutral Point Piloted multilevel inverter using FPGA

Most of actual real time simulation platforms have practically about ten microseconds as minimum calculation time step, mainly due to computation limits such as processing speed, architecture adequacy and modeling complexities. Therefore, simulation of fast switching converters’ instantaneous models requires smaller computing time step. The approach presented in this paper proposes an answer to such limited modeling accuracies and computational bandwidth of the currently available digital simulators.As an example, the authors present a low cost, flexible and high performance FPGA-based real-time digital simulator for a complete complex power system with Neutral Point Piloted (NPP) three-level inverter. The proposed real-time simulator can model accurately and efficiently the complete power system, reducing costs, physical space and avoiding any damage to the actual equipment in the case of any dysfunction of the digital controller prototype. The converter model is computed at a small fixed time step as low as 100ns. Such a computation time step allows high precision account of the gating signals and thus avoids averaging methods and event compensations. Moreover, a novel high performance model of the NPP three-level inverter has also been proposed for FPGA implementation. The proposed FPGA-based simulator models the environment of the NPP converter: the dc link, the RLE load and the digital controller and gating signals. FPGA-based real time simulation results are presented and compared with offline results obtained using PLECS software. They validate the efficiency and accuracy of the modeling for the proposed high performance FPGA-based real-time simulation approach. This paper also introduces new potential FPGA-based applications such as low cost real time simulator for power systems by developing a library of flexible and portable models for power converters, electrical machines and drives.