Mitsubishi Electric Corporation
Real-Time Simulation of Electric Motor and Power Electronics

Opal-RT Technologies’ RT-LAB Electric Drive Simulator was selected and installed by Mitsubishi Electric Corporation (MELCO) in Japan. With a simulation period as low as 8 µs and a precise simulation of inverter PWM switching, including such tiny details as the dead time that is smaller than this actual simulation period, RT-LAB Electric Drive Simulator is the world's fastest and most precise real-time simulator of motor drives and power electronics based systems.

Due to the increasing complexity and costs of projects, and the growing pressure to reduce the time-to-market, testing and validation of complex systems has become more and more important for a company’s design process like MELCO’s.

Opal-RT provided the right solution for Mitsubishi, hardware-in-the-loop simulation. Hardware-in-the-loop (HIL) consists of testing and debugging a real controller (an ECU (Electronic Control Unit)) by connecting it to a motor drive simulated in real-time with a RT-LAB Electric Drive Simulator.

Before adopting HIL testing, Mitsubishi’s development process was a combination of offline simulation and verification using physical prototypes. However, off-line simulation is time consuming due to its slow simulation time and does not validate the actual ECU. In the case of verification using physical systems it is very difficult to achieve a wide range of test conditions or setups; there are also restrictions on the feasibility of the tests due to load conditions and safety concerns. The preparation for a test using a physical prototype is also time consuming and therefore costly.

Mitsubishi’s first objective with hardware in-the-loop simulation was to use HIL simulation as an additional part of the development process, instead of relying solely on offline simulation and building physical prototypes. With HIL, it is possible to experiment with motor designs with varying characteristics and different control strategies. By doing so, Mitsubishi would be able to experiment with a new motor design that does not exist yet.

RT-LAB Electric Drive Simulator

The RT-LAB Electric Drive simulator provides the accuracy needed in simulating electric motor drives for testing their controllers. Despite the difficulty to simulate noise and thermo effects with the current model, Mitsubishi was certain that the model could be adapted to incorporate these capabilities. Mitsubishi would then be able to lift some data required for implementing these features from their offline simulation model.

Since Opal-RT commissioned the system in the second half of 2004, MELCO found that the HIL simulator provided the accuracy comparable to what was only achievable with offline simulation, but at a speed that is a few hundred times faster; the major application of HIL simulation of motor drive is to test and validate the motor controller by connecting it to the simulator.

The RT-LAB Electric Drive Simulator operates the real-time simulation of AC motor drive, including a permanent synchronous motor, an IGBT inverter, an internal PWM controller used for testing and several I/O channels, analog, and digital managed by a 100 MHz FPGA and time-stamped with a 10 nanosecond resolution.

"This achievement represents a major milestone for us, and opens the way for testing of electrical systems that could not be simulated before", said Jean Belanger, President of Opal-RT Technologies Inc., "We are proud to welcome Mitsubishi as one of a growing number of customers who have acknowledged that only RT-LAB Engineering Simulators can deliver the performance and precision needed for this type of application."