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National Instruments is making big investments to advance the graphical system design solution and provide a comprehensive new toolchain for digital energy. This NI toolchain completes the design and test platforms required for power electronics system development.
On the design side, the NI General Purpose Inverter Control (GPIC) is a universal platform for controlling AC-to-DC converters and DC-to-AC inverters that has all the right I/O in a cost-effective form factor. At the heart of the system is the FPGA, which is recognized as the ideal platform for any switch-mode power supply (SMPS) control system.
Now engineers deploying SMPS systems can take advantage of an unparalleled technology of inverter system performance evaluation on the desktop using Multisim and LabVIEW co-simulation. With this technology, you can write graphical FPGA code on the desktop, simulate it against a high-fidelity SPICE simulation of the SMPS analog plants, and get high-fidelity results.
This document introduces these technologies and gets you started with LabVIEW and Multisim co-simulation.
Table of Contents
- Introduction to Multisim and LabVIEW Applications
- How to Perform a Desktop Simulation of an Inverter System Using LabVIEW and Multisim Co-Simulation
- Additional Resources
Introduction to Multisim and LabVIEW Applications
The closed-loop point-by-point simulation between analog circuits and digital systems replaces the conventional approach of simulating both ends separately and then loading the analog simulation output as a batch file into the digital simulator ending with a lot of missing system dynamics and low-accuracy designs.
The Multisim simulation is optimized for accurate analog and mixed-signal circuitry, and you can use the large set of SPICE models in Multisim 12.0 provided by leading semiconductor manufacturers as well as a parametrizable component optimized for inverter design such as diode, transformer, and IGBT models.
The LabVIEW simulation engine helps you to effectively design and implement the control logic through a graphical, data flow representation of the FPGA control code.
After the system performance is verified on the desktop, the inverter control code can be compiled to the FPGA target on the NI sbRIO-9606 where the GPIC plugs in to become a deployment-ready commercial embedded system for high-volume grid-tied inverter, DC/DC converter, and motor/generator drives.
How to Perform a Desktop Simulation of an Inverter System Using LabVIEW and Multisim Co-Simulation
This design example of a three-phase single-level inverter covers the basics of simulating an inverter system in Multisim and LabVIEW and deploying it to NI Single-Board RIO and the GPIC (NI 9683).
Inverter Circuit Setup in Multisim
The analog circuitry of the inverter consists of the following:
- A three-phase single-level inverter stage of six MOSFET switches that are controlled by the FPGA logic (discussed later in this tutorial)
- A filter stage to obtain a clean single frequency 60 or 50 Hz signal
- A three-phase load output stage at which the voltage and current are sampled in Multisim and transferred to LabVIEW as input for the FPGA control blocks
Figure 1. Analog Circuitry in Multisim
Multisim provides options for advanced and detailed modeling of the analog components in the circuit such as the following:
- Parametrizable power components such as MOSFET switches
Figure 2. Parametrizable Basic IGBT Model in Multisim
- Nonideal RLC components for better parasitic modeling
Figure 3. Nonideal RLC Components in Multisim
After the analog circuit is modeled, the HB/SC connector should be placed at the inputs and outputs to provide communication with the controller designed in LabVIEW, as shown in Figure 1. In Multisim, you can find the HB/SC connector in the place>connectors>HB/SC connectors menu.
FPGA Control Logic in LabVIEW
The graphical system simulation is performed in LabVIEW. After the system interface VI is started, both Multisim and LabVIEW simulation engines are run in the background to perform a closed-loop, variable time-step simulation of the complete system.
The Multisim analog circuit is placed into a LabVIEW control design and simulation loop along with the FPGA IP blocks, as shown in Figure 4.
Figure 4. Complete System Simulation of a Three-Phase Inverter
The variable time-step co-simulation between Multisim and LabVIEW of closed-loop systems accounts for important behaviors that are essential in judging the overall system performance including nonlinearities, resonances, and harmonics very early in the design stage. Moreover, the design solution is completed by combining simulation tools with integrated hardware implementation tying the analog world to FPGA platforms. In other words, the simulation, once performed accurately, is ready to deploy on a GPIC-based system.
You can download the design files for this example in the attachments section.
Additional Resources
Set Up LabVIEW and Multisim Co-Simulation
Join the NI Power Development Community
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