FMTC engineers designed, optimized, and evaluated hybrid hydrostatic drivetrain alternatives with Model-Based Design.
Using Simulink and Simscape, they developed models for each component in a typical hydrostatic drivetrain, including the driving motor, hydraulic pump, hydraulic motors, and a torque load.
For each component, the team conducted experiments in the lab, measuring torque, speed, and pressure. Using a toolbox they developed based on MATLAB and Optimization Toolbox™, they estimated model parameters based on these measurements. They then developed lookup tables that mapped pressure, speed, and stroke volume to energy efficiency.
The team also estimated internal inertia, time delays, and other parameters to more accurately model the dynamic behavior of the components with Simulink and Simscape.
The engineers then built a system model from the component models, linking them with valves, hydraulic resistances, and other hydraulic circuit elements from Simscape Fluids™.
They verified and refined the system model by running simulations in Simulink and comparing the results with measurements of the complete driveline.
Once they had an accurate model of the driveline, the team developed Simscape models of two energy-storage components: a supercapacitor with a DC-DC converter and a hydraulic accumulator with its associated valves and lines.
They integrated each of these components into the system model separately, and used in-house methodologies to develop and implement optimal control algorithms in MATLAB for the two hybrid drivetrains. These control algorithms calculate the settings for drivetrain components, such as the swash plate angles for the hydraulic pump and motors.
The team then performed closed-loop simulations in Simulink across a range of capacitor types and accumulator sizes, estimating TCO for each configuration.
FMTC plans to use Simulink Coder™ to generate code from its plant models to support real-time hardware-in-the-loop testing.