PCKA has been involved with the computer simulation of power-electronic-based electromechanical systems since it opened its doors. The computer simulation programs that were available in the 1980’s and into the early 1990’s were lacking the features convenient for simulation of large-scale, power-electronic-based systems. PCKA developed tools and simulation technologies necessary to conveniently analyze and optimize the engineering challenges encountered in these systems. In an effort to fill this void, PCKA developed and patented two software technologies: the Automated State Model Generator (ASMG) and Distributed Heterogeneous Simulation (DHS). The ASMG (U.S. Pat. #7353157) is software that provides the convenience and speed for implementing a simulation and the speed of computation desirable for large power-electronic-based electromechanical systems. DHS (U.S. Pat. #7490029) is integration software that enables the interconnection (co-simulation) of any number of dynamic subsystem simulations on a single or multiple computers, across a local internet, or geographically through the Internet. DHS support numerous simulation programs/languages and provides a means of simulating the transient and steady-state performance of large-scale systems at a speed and level of detail previously unachievable. PCKA’s software for advanced modeling, simulation, design, and analysis techniques has led to a revolutionary integrated system-of-systems design environment focused on minimizing costs and providing a rapid prototyping and demonstration capability for power, thermal, and propulsion systems. These techniques are encompassed within PCKA’s FastSim Simulation Suite including the ASMG for SimulinkTM, DHS, Distributed Heterogeneous Optimization (DHO), Partitioned Finite-Element (PFE), and the Thermal Suite. These software tools, which are described in this section, have been adopted by numerous industries and government agencies.
FastSim Simulation Suite
FastSim is an easy-to-use system-of-systems simulation environment built around PCKA’s modeling and simulation tools, including the Automated State Model Generator (ASMG), Distributed Heterogeneous Simulation (DHS), Distributed Heterogeneous Optimization (DHO), and Partitioned Finite-Element (PFE). This simulation environment allows component or subsystem designers, system integrators, and program managers to work together more efficiently and effectively than was previously possible with exiting COTS simulation tools. FastSim sets the stage for advanced design and analysis features including system-level optimization and automated average-value modeling. The FastSim environment consists of three main components used to build, store and run system simulations; the Composer, Model Repository, and the Agent, respectively. All of these components work together to provide a complete integrated simulation environment. Individual models or applications can quickly be built into a larger system using the Composer. The system or components can then be saved to a Model Repository for distributed use. The system as a whole can be exercised using the Agents that can be run on local as well as remote computers. Automated State Model Generator (ASMG) The ASMG for SimulinkTM Toolbox is an easy to use tool built on top of PCKA’s patented ASMG algorithms for the simulation of systems that can be represented as electrical-equivalent circuits such as power electronics, electric machinery, magnetic circuits, mechanical and thermal systems. The ASMG automatically generates the governing differential equations based upon a schematic description of the circuit and the seamless integration with the Simulink framework enables the use of all the features offered by Simulink, such as hierarchical model descriptions, library development and masking capabilities, choice of integration algorithms, and the direct integration with the associated system controls. The ASMG supports the simulation of a wide variety of circuits and systems, including linear, nonlinear (saturable), time-varying and switched networks, wherein the tool is capable of generating the state-space model accurately and automatically across the topological transitions due to a change in the switching configuration. This capability eliminates the need for users to manually derive the state-space equations governing the system, which is especially convenient when simulating switched networks that have many topological configurations and when re-using portions of models in new systems. Since the switching elements are not represented as fictitious resistors (with very small or very large values) as done with many non-state equation based circuit simulators, spurious state dynamics are not introduced when simulating practical power-electronics-based systems and switched circuits in general. Additionally, the ASMG utilizes state of the art degeneration algorithms that enable topological accuracy to be maintained even in the presence of mathematical transformations commonly utilized in electric machine modeling. These features result in fast, accurate circuit simulation. The ASMG is quickly emerging as the circuit simulator of choice for complex power electronic and electromechanical systems. It has been adopted by numerous government, industry, and university research organizations and is also utilized to support course instruction at the undergraduate and graduate levels at several universities. Distributed Heterogeneous Simulation (DHS) The patented Distributed Heterogeneous Simulation (DHS) technology facilitates the synchronized co-simulation of any number of dynamic subsystem simulations implemented in the same or different software environments. The DHS-enabled system simulation can be executed on a single computer, distributed across a local internet, or geographically distributed across the Internet and provides a means of simulating the transient and steady-state performance of large-scale systems at a speed and level of detail previously unachievable. In fact, for one system a greater than 1000-fold increase in simulation speed was observed. DHS coupled with FastSim establishes a collaborative system design and analysis environment wherein intellectual property can readily be protected. Distributed Heterogeneous Optimization (DHO) DHO is an optimization tool based upon evolutionary (genetic) and particle swarm algorithms. Such optimization algorithms (i.e., population-based algorithms inspired from genetic processes as observed in nature) have been finding successful application in real-world engineering optimization problems for many years. PCKA, in cooperation with a leading university, developed the DHO general purpose optimization software under a Phase II. PCKA’s implementation has adapted and incorporated a state-of-the-art multi-objective evolutionary algorithm. DHO features the functionality of distributed optimization, thus reducing the overall time needed to obtain a solution. Specifically, the objective function evaluations (required by the evolutionary optimization algorithm) are distributed to a number of computers in a master-slave protocol configuration. Therein, a main application communicates with the corresponding evaluators, exchanging variables and objective/constraint function values, while also monitoring their execution time for possible timeouts due to unpredictable errors. Evaluation of the objective function may include the execution of a MATLAB/Simulink time-domain simulation. DHO has been applied to many engineering problems including electric machine design, power system control optimization, and parameter identification. Partitioned Finite-Element (PFE) Finite element (FE) analysis has opened the door to the modeling and analysis of devices based upon their geometrical design. FE algorithms tend to be computationally intense, requiring high-end computational capabilities and/or extensive amounts of time to conduct simulation studies. PCKA has, however, developed and demonstrated a method of partitioning the FE problem into a set of sub-problems, which can improve the required overall computation time. The procedure has been implemented for both linear and nonlinear magnetics. Next, a highly efficient method of interfacing the partitioned FE model to a time-domain circuit simulation was developed. This method incorporates circuit constraints (such as those arising from wye-connected windings in an electric machine) directly into the FE solution procedure. Constrained Generator Enhancement Tool (COGENT) COGENT is a software tool that enables the rapid design of electric machines. It was developed by combining capabilities provided by DHO and PFE all within a common scripting environment using the Lua scripting language. The scripting environment allows the geometry of an electric machine to be easily defined. It also provides the capability to define free parameters that can be adjusted by DHO to identify designs that exhibit advanced performance. The ability to quickly and easily change the values of the parameters makes the optimization procedure more efficient, because it enables the precise calculation of model geometry based on parameter values. In addition to model construction, COGENT allows the user to define studies to evaluate potential designs. This includes defining the rotor position and excitation currents flowing in all windings (subject to the appropriate circuit constraints). In addition to static studies, time-domain simulations can be carried out within the scripting environment to define the model inputs. COGENT has been successfully employed to improve the torque and power density of a standard non-symmetric generator.
In addition to the FastSim Simulation Suite, PCKA has developed software tools for the modeling, simulation, and analysis of thermal systems. These include the Thermal Management System (TMS) toolset, the AFRL Transient Thermal Management Optimization (ATTMO) toolset and the MIRCO-HX. These toolsets support the design and detailed analysis of thermal systems from heat exchangers to integrated cooling systems to vehicle-level solutions.
Thermal Management System (TMS)
The Thermal Management System (TMS) toolset is an open source MATLAB/Simulink modeling library for the rapid transient analysis of thermal systems including air cycle machines, fuel thermal management, and heat transfer between adjacent bays and/or the environment across an entire operation scenario. The open source nature allows transparency between model developers and system integrators and enables further customization to match a specific design, architecture, or hardware results.
AFRL Transient Thermal Management Optimization (ATTMO)
While the TMS toolset addresses dynamic fuel and air cycle systems, a need was identified for dynamic modeling of vapor-cycle systems. As a result, PCKA in collaboration with a leading university developed the AFRL Transient Thermal Management Optimization (ATTMO) toolset. This toolset utilizes many of the successful approaches of the TMS toolset (transient, modular, transparent) to support the rapid development of vapor-cycle system models. These integrated system models enable the investigation and development of advanced control algorithms necessary to support the dynamic cooling and power requirements associated with advanced aircraft architectures.
Under an SBIR project, PCKA developed the MICRO-HX software to accelerate the concept initiation to hardware development timeframe for emerging heat exchanger technologies. Direct simulation through 3-D computational fluid dynamics was used to assemble a thermal/hydraulic database that accurately resolves microscale phenomena untreatable through conventional correlative methods. Collaboration with industry-leading manufacturers provided software validation and state-of-the-art development considerations, while focusing PCKA’s tool on the leading candidate technologies. Rapid access to the power of high-fidelity CFD is offered in both standalone and system-level (Simulink) forms, bridging the gap between component-level design and dynamic, mission-scale predictions. The software is engineered to directly impact design cycles for microstructured heat exchanger technologies, including microchannel, microtube, open-cell foams, and graphite-based devices.
Power Quality Analysis (PQA) Tool
The Power Quality Analysis Tool (PQA Tool) provides the capabilities to systematically and consistently process and visualize data and compare them to existing specifications and standards that define performance metrics. The target application is the evaluation of electrical power quality according to a variety of standards; however, the tool’s data processing routines support the analysis of generic data without specifying performance standards. The PQA Tool thus eliminates the need to manually process different data sets and multiple standards, devise complicated algorithms, or struggle with plotting routines. Providing such a simplifying software tool and the underlying analysis procedures encourages more rigorous validation procedures, which in-turn will lead to improved hardware designs, and reduce the time-to-market for complex interconnected systems.
The PQA Tool provides intuitive interfaces for streamlining the analysis of electric power data or any other measurements. The tool supports simultaneous analysis of transient (dynamic) events, frequency spectrum calculations, and so-called steady-state metrics including average, rms, ripple, and distortion as defined in power quality standards such as MIL-STD-704, MIL-STD-461, and MIL-STD-1332. An end-user can seamlessly load datasets from multiple data sources (simulation, data acquisition equipment, and oscilloscopes), analyze the individual datasets in time- and frequency-domain, check those measurements against multiple specifications, and group together similar signals/measurements in ensuing plots to provide a comparative view of the results. All processing routines are accessible through a graphical user interface (GUI) or a command line interface (CLI). The PQA Tool GUI requires no programming knowledge and PQA Tool CLI provides more advanced users ability to script a variety of performance analyses and extract relevant results.