Native simulation

native.Simulation simulates a system built in motulator in C. It has the interface and the results of the simulation of motulator, so a script only replaces the simulation object. For example, with mdl and ctrl built as in Getting started:

from motulator.drive import utils

from motulator_export import native

sim = native.Simulation(mdl, ctrl)  # Instead of model.Simulation(mdl, ctrl)
res = sim.simulate(t_stop=1.2)
utils.plot(res)

To try it out, run python examples/native/plot_2kw_ipmsm_fvc.py, see Getting started.

The control system runs the C port of its algorithms, and the system model runs as C models of its subsystems, integrated with the same solver steps as in motulator. The C code is compiled at the first use and cached. The examples show the native simulation of systems of the motulator examples, including a parameter sweep.

Run times

Run times of simulate on one core of a laptop, with motulator 0.15.0:

System	PWM model	motulator	Native	Ratio
5.6-kW PM-SyRM, GradNet models, 1.75 s	zero-order hold	9.9 s	0.31 s	32
5.6-kW PM-SyRM, GradNet models, 1.75 s	carrier comparison	27.9 s	0.87 s	32
2.2-kW IPMSM, sensorless FVC, 1.6 s	zero-order hold	3.3 s	0.09 s	36
2.2-kW IPMSM, sensorless FVC, 1.6 s	carrier comparison	9.1 s	0.24 s	38

Accuracy

The results agree with motulator to the rounding errors, about 1e-12 relative to the signal magnitudes. With carrier comparison (pwm=True) or a diode bridge (DiodeBridgeDCBus), a rounding error can change a switching instant or a step size, after which the results differ more. The simulations of motulator itself are equally sensitive to the rounding errors.

Good to know

• The references and the load torque can be constants, StepSignal objects (evaluated in C, fastest), or functions of time (called from C).

• As in motulator, the results are also stored in mdl and ctrl, and a subsequent call of simulate continues the simulation.

• Gate blocking (ctrl.set_enable) is not supported. Other unsupported systems raise NotImplementedError when the simulation is created, see Supported systems.