Modelica is an open, tool-independent modeling language for the dynamic description of physical systems. A major advantage is that multi-domain systems consisting of e.g. mechanical, hydraulic, electrical as well as control components can be integrated very easily in one overall model. These models can be used in a wide range of simulation tools and software solutions on the market that support the Modelica standard.
With BRSL, Bosch Rexroth offers a comprehensive model library that provides everything needed to create a representation of the static, dynamic and kinematic properties of an entire machine or system in the form of a digital twin. The models were developed by our simulation experts based on many years of experience and have been tested in practical use at Bosch Rexroth.
For the simulation of electric drives in a system context, the BRSL includes components that represent the dynamic behavior of electric motors as well as the control engineering part of converters.
Areas of application
The usage of a simulation based on BRSL results in various added values:
- Fast and cost-effective feasibility studies
- Holistic approach to system simulation (Process + machine + drive technology + control)
- Comparison and validation of alternative drive and control concepts
- Representation of "inner states" of the machine or its elements, which are difficult or even impossible to measure on the real product
- Optimization of the performance and energy efficiency of the machine
- Possibility of analyzing unlimited scenarios
- Representation of the interaction of the individual system components and the interdependencies between them
Model structure and parameterization
The library contains pre-parameterized models of Bosch Rexroth products as well as generic models for individual parameterization, each containing a rotary servo motor and the control part of the converter. Synchronous motors as well as asynchronous motors are available.
Using the inputs, the command values for the selected control mode (e.g. velocity or torque command values) are provided to the model. Based on these input values and the dynamic properties of the motor/converter combination specified in the model, the angle, angular velocity and angular acceleration of the motor shaft as well as the output torque are calculated. These values are passed on to the subsequent model components via the output of the model.
Parameterization of the model is quick and easy for Bosch Rexroth products by selecting the type codes of the motor and converter from a drop-down menu (see (1) and (2) in the figure), as well as the supply voltage (see (3) in the figure) and the desired control mode (see (4) in the figure). All parameters are already included in the model, so that modeling errors are minimized and the time-consuming determination of parameters from data sheets, for example, is no longer necessary.
Usage of BRSL components
The following is a simple example model of how the electric drive models are used. The speed reference for the motor is passed to the input of the motor/converter component. A mass is connected to the output of the component, which is driven by the motor.
A second example model, a variable-speed pump drive, is used to illustrate how the electric drive models can be used in a system context. It can be seen that components from different domains (mechanical, electrical, hydraulic and control) can work together without any problems. The electric drive uses a coupling to drive the pump, which then delivers hydraulic fluid and moves the cylinder. The measurement of the cylinder position and the pressures in the system are processed and a new command value is created for the drive controller.
Notes
The BRSL was primarily developed for use with the simulation tools SimulationX as well as Dymola and has been extensively tested with them. The licenses listed below are available in two variants:
- Library for electrical drives and motors from Rexroth and a generic library for basic mechanical elements
- Full library with electrical drives and motors from Rexroth, basic mechanical elements and a huge amount of hydraulic components from the Rexroth product portfolio
All are rental licenses with an annual fee.
If you have any questions about compatibility with specific tools or for general BRSL topics, please feel free to contact us at any time:
virtual.engineering@boschrexroth.de
