RT23 | HIL Assisted Design for PHIL Real-Time Electrical Machine Power Emulation

The proposed system is a Permanent Magnet Synchronous Machine (PMSM) emulator that employs the concept of Power-Hardware-In-the-Loop (PHIL). PHIL systems emulate a physical electrical system by means of a power system that includes elements such as the Digital Real-Time Simulator (DRTS), the Power Amplifier (PA), the Coupling Network (CN) and the Interface Algorithm (IA). Hardware In the Loop (HIL) and PHIL differ regarding the signals exchanged between the simulator and the DUT. With PHIL, not only the controller of the DUT can be tested, but also the hardware at its rated power, without needing installation in the real environment where it is going to be used. PHIL is a powerful technique for testing and demonstrating systems in a rigorous and dynamic manner that is not achievable with other methodologies. With that being said, now it is possible to go deeper into the details of the proposed system. From the hardware point of view, the PMSM emulator of this project is made of a three-phase Voltage Source Inverter (VSI) connected to a RL coupling network, and of voltage and current sensors. From the software point of view, the system is made by the digital real-time simulator, where all the calculations and controls of the emulated PMSM system take place. Inside this unit, there are an electrical and a mechanical model of the PMSM under emulation. The mechanical model computes the speed of the emulated machine based on the current flowing on the PHIL circuit. The electrical model calculates the phase currents that would flow in the original circuit based on the acquisition of the voltages applied by the DUT. With the computed currents, the emulator can estimate the back-emf voltages that the real machine would apply in the real system, which instead, are applied by the VSI. In order to have experimental results of the proposed system, the HIL OP4610XG from OPAL-RT Technologies is employed in this project. Besides that, the DUT considered is a three-phase inverter capable of controlling speed or torque of the PMSM, being controlled by a National Instruments System-on-Module (sbRIO-9651) in a dedicated control board (PED-Board). In order to validate the proposed PMSM emulator, first it is needed to obtain the ideal waveforms of the DUT controlling a real PMSM and use them as references for comparisons. For this, the PWM outputs of the DUT controller are connected to digital inputs of the OP4610XG, that emulates a three-phase inverter connected to an PMSM and then the reference waveforms can be obtained. On the other hand, to validate the proposed PHIL system, the PMSM model inside the OP4610XG is replaced by a RL coupling network connected to a three-phase inverter. The inputs of this second inverter are now connected to the outputs of a second PED-Board, which will execute the complete machine model and control this inverter. In this implementation it is important to highlight that both DUT and PHIL hardware, coupling network, sensors and power supplies are implemented inside the HIL environment of OP4610XG. In other words, the OP4610XG is used to realize a simulation of a simulation, making the system even more eco-friendly and safer, while being able to validate all control functionalities and physical responses of the proposed PHIL. This project has already obtained significant results using the presented methodology of testing, for instance, the validation of the proposed PMSM emulator using different coupling inductances. This implementation brings flexibility without losing accuracy, since any parameter of hardware can be changed inside OP4610XG without the need of physical connections.