Abstract
Keywords: HV system, Motor, Model, Simulation, HILS
Since Toyota Prius appeared in 1997, hybrid vehicles (HV) have been proven to be a very efficient approach for environment protection and fuel consumption. Compared with a conventional vehicle with only engine, a hybrid vehicle, consisting of engine and one or more electrical motors in power-train, is complex. Therefore, much more parameters have to be customized, and more time is required to make the system optimized. In order to satisfy the paradox of reducing the development period while ensuring system performance, model based development (MBD) method plays a very important role. One of the important MBD approaches is hardware in the loop simulation (HILS), which is used to verify and/or debug the control logic efficiently by simulation without using a real motor or engine. Since HILS works in real time, the model implemented in HILS should not only be precise, but also be processed very quickly in order to make the HILS work efficiently.
Conventionally, a so called dq coordinate 2-phase model is usually used in motor simulation. Coordinate transformation between 3-phase and dq 2-phase coordinate, however, is required in the simulation using this dq motor model. This transformation not only causes simulation error due to its nonlinearity, but also needs long time to be processed due to its complicated calculation.
This paper demonstrates development of a new 3-phase motor model for interior permanent magnet synchronous motors used in hybrid electrical vehicles widely, and its application in HILS for hybrid system development. With this new 3-phase motor model, 3-phase currents of the motor can be calculated directly from 3-phase voltages without using the coordinate transformation.
To use the 3-phase motor model for simulation, calculation of the inverse matrix of the motor inductance matrix is required, while the inverse matrix calculation is complicated. Hence, a very efficient and simple calculation algorithm is also developed to make the inverse matrix be calculated precisely and quickly.
Then this 3-phase model is implemented into 2 types of HILS simulators called RT-LAB and MotorBox. The RT-LAB based simulator succeeded to put the real time motor simulation into practical use, and made it possible to debug and test motor ECU completely virtually. Later, the HILS performance was further improved by the MotorBox based simulator, which is now an important component of the standard HV-HILS system in Toyota.
The above motor HILS have been successfully applied to the development of motor ECU, for example, hybrid vehicle fail-safe control logic development and verification. The application results show that, the motor HILS are very efficient both to speed up the motor control logic development and to improve ECU quality further as one of the model based development environments.