F2008-12-098
Motor Model for IPM and its Application in HILS for HV System Development
Since Toyota Prius appeared in 2000, hybrid vehicles have been proven to be a very
efficient approach for environment protection and fuel consumption. Compared with
conventional vehicles with only engine, hybrid vehicles, consisting of conventional
engines and electrical motors in power-train, are complex. Therefore, much more
parameters have to be customized, and more time is necessary to make the system
optimized. In order to satisfy the paradox of reducing the development period while
ensuring system performance, model based design (MBD) method plays a very important
role. One of the important approaches for MBD is HILS (Hardware in the Loop
Simulation), 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 for the HILS to work efficiently.
Conventionally, a so called dq coordinate model is usually used in motor simulation.
Coordinate transformation between 3-phase and dq-phase, however, is necessary in the
simulation using this dq motor model. This transformation not only cause simulation
error due to its nonlinearity, but also need long time to be processed due to its
complicated calculation.
This paper demonstrates the development of a new 3-phase motor model of interior
permanent magnet (IPM) motors widely used in hybrid vehicles, and its application in
HILS for hybrid system development. First, a 3-phase model was developed, by which
the 3-phase current can be calculated directly from the 3-phase voltage without
using the coordinate transformation.
To use this 3-phase model for simulation, calculation of the inverse matrix of the
motor inductance matrix is required, and the inverse matrix calculation is
complicated in general. Hence, a very efficient and simple calculation algorithm is
also developed to make the inverse matrix calculation be calculated precisely and
quickly.
Then this model was implemented in 2 kinds of HILS simulator called RT-LAB and
MotorBox. The RT-LAB based simulator succeeded to bring motor simulation in to
practical motor HILS, made it possible to debug and test motor ECU completely
virtually. The motor HILS performance was further improved by the MotorBox based
simulator, which is an important component of the standard HV-HILS in Toyota.
The motor HILS have been applied to the development of motor ECU, for example,
hybrid vehicle fail-safe control logic development and verification. Application
results show that, this HILS is a very efficient system both to speed up the control
logic development and to raise ECU quality further as one of the model-based
development environments.
Session: Powertrain