Drive System#
Machine drives are sampled-data systems, consisting of continuous-time systems and discrete-time systems as well as the interfaces between them [1], [2]. The figure below shows a generic example system. The same architecture is used in motulator.
The continuous-time system (named mdl in Examples) is the model of a physical machine drive system, typically consisting of a machine, mechanics, and power converter. The continuous-time system may have external inputs, such as a load torque.
The discrete-time controller (named ctrl) contains control algorithms, such as the current control and speed control. The reference signals could be, e.g., the speed and flux references. The feedback signal \(\boldsymbol{y}(k)\) typically contains the measured DC-bus voltage and stator currents.
Digital control systems typically have a computational delay of one sampling period, \(N=1\). The PWM block shown in the figure models the carrier comparison, see more details in Converters. The carrier comparison is implemented in the class motulator.drive.model.CarrierComparison
. If the switching ripple is not of interest in simulations, the carrier comparison can be replaced with zero-order hold (ZOH).
References