Elaborate Modeling Technology (Circuit/Control)
- Generating Highly Accurate Machine Models Indispensable to Model Based
Design (MBD) -
These technical reports introduce the scope of JMAG's technological development.
The final edition for this series provides a deeper look at JMAG's modeling
technology.
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Ideal MBD and Its Challenges
Model based design (MBD) has been around the field of circuits/controls
for motors for a long time, but has not been at the forefront for some
time. However, MBD allows the control algorithms to be evaluated with simulations
before a prototype is built by utilizing a model that can accurately simulate
the behavior of motors. The necessity for an MBD development method is
reinforced by limit design and the stricter time allotted for product development.
The demand to bring a product to market as quickly as possible has prompted
the separate processes of motor design and circuit/control design to be
undertaken simultaneously. Products designed in a V-type workflow that
utilizes simulations can be achieved by employing MBD. The affects of magnetic
saturation and spatial harmonics on the control algorithm of motors as
miniaturization and high output advance cannot be ignored. On the other
hand, the development of sensorless controls utilizing magnetic saturation
and saliency demands a deep understanding of the motor behavior.
Several hurdles need to be overcome to implement MBD in a development process
that requires more versatility to satisfy the stricter demands of product
development. An optimal tool to provide motor designers and circuit/control
designers with the capability of evaluating different types of models simultaneously
is necessary in the design process. This type of tool also needs to provide
the highest level of accuracy. A simple linear model is not sufficient
to analyze control algorithms because the behavior of motors becomes more
nonlinear depending on the drive conditions.
Accuracy Required for Motor Models
The behavior of motors that are heavily loaded or driven at high rotation
speeds is complex. JMAG can accurately obtain these kinds of complex phenomena
utilizing technology centered on finite element analysis (FEA). The losses
of motors rotating at high speeds, such as iron loss, cannot be ignored.
The inductance of motors also decreases as the magnetic saturation increases,
and the affects of slot harmonics on motors is vital to the back EMF waveform
necessary for sensorless control. JMAG offers highly accurate analyses
to engineers which provides valuable insight to phenomena important to
motor design.
However, the parameters of the motor models used for control simulations
are conventionally based on lumped parameters. For instance, an equivalent
circuit for a PM synchronous motor is constructed using the resistance,
inductance, and back EMF produced by the magnets. The behavior of motors
can be accounted for in control simulations if each of these aspects of
the motor is understood. Nonetheless, the complex phenomena described previously
requires that the most accurate parameters are expressed in the simulations.
Therefore, motor models which combine inductance that accounts for the
nonlinear characteristics using a variety of methods, such as lookup tables,
to use in control simulations are required. JMAG has progressively evolved
to offer this type of cutting-edge modeling technology that is capable
of generating motor models for circuit/control simulations from a simulation
model used for the motor design.
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