Fast and Reliable Implementation of High Precision Motor Models for Real-Time HIL Applications with RT-LAB.JMAG

RT-LAB.JMAG at a Glance

RT-LAB.JMAG is a software module developed in collaboration with JMAG Group , developer of the popular JMAG simulation software for electromechanical design and development. RT-LAB.JMAG is designed for use in the real-time simulation of motor models using inductance and back EMF data generated by Finite Element Analysis (FEA) methods. The FEA technique is required when classical D-Q models cannot be used due to large asymmetry in the motor construction generating non-sinusoidal fluxes and currents.  This is important for hybrid vehicle manufacturers using high-speed motors optimized for space and cost.    

RT-LAB.JMAG™

RT-LAB.JMAG™  is a software toolbox for Simulink for high-precision real-time simulation of motor drives on eDRIVEsim® Hardware-in-the-Loop simulator. Equipped with the most powerful COTS PC processors and the latest FPGA development environments, eDRIVEsim is the fastest Power Electronics HIL simulator available on the market today.

RT-LAB.JMAG combines Opal-RT's RT-LAB™ real-time simulation technology with JMAG-RT®, part of the JMAG Finite Element Analysis (FEA) tool suite from JMAG Group (Japan). This enables the simulation of complete motor drives (including switching power inverters) with much higher precision compared to conventional motor models.

This unique environment allows the simulation numerous types of transient and fault conditions difficult or impractical to do with the real system (faults on motor terminals, faults on converter IGBT, faults between DC and AC busses, no-pulse and natural rectification modes).

Sample applications include air conditioners, hybrid drives, machine tools, compressors, etc.

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Benefits of FEA-based Simulation

One of the most critical issues facing engineers conducting real-time simulation of advanced motor drives is how to attain acceptable model accuracy with an achievable simulation time-step. While a simple Park two-axis model is usually sufficient to conduct most HIL tests, increased model precision may be required for the design of advanced motor drives. For example, some PMSM drives have very high cogging torque levels, which cannot be easily ignored. In other cases, the engineer may desire accurate modeling of inductance variations for applications such as the development of sensorless control strategies.

FEA-based real-time simulation resulting from the integration of JMAG-RT with RT-LAB addresses these issues. Because of RT-LAB.JMAG's powerful code optimization and usage of lookup tables, real-time simulation of FEA-based PMSM drives can be conducted at time-steps in the range of 20 microseconds on Intel CPUs. When executed on eDRIVEsim's FPGA board, time steps below one microsecond are achieved, providing radically improved sampling time performance compared to regular d-q models, along with much higher simulation accuracy.

The results obtained with the standard D-Q model, the off-line JMAG models and the real-time models are presented above.

It can be seen that the D-Q model simulates the average value of the torque while the JMAG and the real-time model simulate the torque distortion.

These very accurate models are implemented in SIMULINK for real-time simulation at about 10 us to 20 us time step on standard multi-core PENTIUM processors.  It can also be simulated on FPGA chips at time step of 250 nanoseconds to simulate high-speed PMSM motors.