🏔️High Level Blocks

The following blocks are submodels composed of primitive blocks. Their time_mode may be Discrete, Continuous, or Hybrid.

More about time_modes.

Chassis - Axle

Implements one axle system of an automobile. Has the following features:

• Computes a longitudinal force as a function of the applied propulsion and/or braking torque to its wheels.

• Accounts for effects of rotating inertia.

• Calculates drag from rolling resistance.

More information about the block.

• Parameters

  • whl_radius_m. The rolling radius of the wheels in meters.

  • Crr. https://en.wikipedia.org/wiki/Rolling_resistance#Rolling_resistance_coefficient

  • axel_rotation_inertia_kgm2. The rotational inertia of one axle in kg-m^2.

• Inputs

  • axle_trq_Nm. The propulsion and/or braking torque to its wheels in Newton-meters.

  • axle_linear_spd_mps. The longitudinal speed that the axle is traveling at in meters per second. e.g. the speed of the vehicle the axle is connected to.

  • axle_vertical_load_N. The force pushing the axle down on to the ground in Newtons. i.e. normal force used for rolling resistance calculation.

• Outputs

  • force_N. The longitudinal force applied to the vehicle body it is connected to, in Newtons.

  • whl_rotational_spd_radps. The rotational speed of the axle wheels in radians per second.

• Time mode. Continuous

Chassis - Longitudinal Body Two Axle

Implements a automotive vehicle chassis with the following features:

• Front and Rear Axles. See Chassis - Axle block.

• Aerodynamic drag force. https://en.wikipedia.org/wiki/Drag_(physics)#The_drag_equation

• Dynamic Front / Rear weight distribution. Uses veh_cg_rear_ratio and veh_cg_height.

• Longitudinal dynamics. e.g. integration of a = F/m.

More information about the block.

• Parameters

  • mass. The mass of eth vehicle body and all components and cargo assumed to be fixed to it.

  • Rho. Density of air in kg/m^3.

  • Cd. https://en.wikipedia.org/wiki/Drag_coefficient

  • frontal_area. The "cross sectional area" in m^2 as defined in https://en.wikipedia.org/wiki/Drag_(physics)#The_drag_equation

  • Crr. https://en.wikipedia.org/wiki/Rolling_resistance#Rolling_resistance_coefficient

  • whl_radius_m. The rolling radius of the wheels in meters.

  • axel_rotation_inertia_kgm2. The rotational inertia of one axle in kg-m^2.

  • veh_cg_rear_ratio. Fraction of mass over the rear axle when vehicle is at rest. Must be between 0 and 1, where 1 is all mass on rear axle.

  • veh_wheel_base. The distance between the front and rear axles in meters.

  • veh_cg_height. The distance that the center of gravity is above the road level in meters.

• Inputs

  • front_axle_trq_Nm. Torque applied to front axle in Newton-meters.

  • rear_axle_trq_Nm. Torque applied to rear axle in Newton-meters.

• Outputs

  • veh_spd_mps. The longitudinal speed of the vehicle in meters per second.

  • front_whl_spd_radps. The rotational speed of the front axle wheels in radians per second.

  • rear_whl_spd_radps. The rotational speed of the rear axle wheels in radians per second.

  • veh_distance_km. The total distance travelled by the vehicle in kilometers.

• Time mode. Continuous

Combustion Engine

Implements a basic internal combustion engine as a simplified torque source with the following features:

• Peak torque curve. Implemented using 1D lookup table.

• Engine efficiency. Implemented using a 2D lookup table.

More information about the block.

• Parameters

  • eng_spd_vector_radps. The speed break points for the peak torque curve in radians per second.

  • eng_peak_trq_vector_Nm. The torque values of the peak torque curve.

  • eng_fuel_consumption_trq_vector_Nm. Fuel consumption map torque break points in Newton meters

  • eng_fuel_consumption_map_gps. Fuel consumption table data in grams per second

  • fuel_density_gpL. Fuel density in grams per liter

  • fuel_energy_density_MJpL. Fuel energy density in Mega Joules per liter

• Inputs

  • eng_spd_radps. Engine speed in radians per second.

  • eng_throttle_norm. Normalized engine throttle, e.g. fractional request for available torque.

• Outputs

  • eng_trq_Nm. Engine torque in Newton meters

  • eng_heat_gen_pwr. Engine heat generation in Watts

  • eng_fuel_consumption_gps. Engine fuel consumption in gram per second

• Time mode. Continuous

Electric Motor

Implements a generic 4 quadrant electric motor with the following features:

• Parametrized peak torque map. Using the peak_power_watts and peak_torque_Nm parameters, and the mot_spd_radps (rotational speed), it computes the instantanous peak torque available. This peak torque is assumed available to in all 4 torque-speed quadrants.

• Speed based torque derating. Decreases the available torque to zero. Start decreasing at peak_spd1_radps, and reaches zero at peak_spd2_radps.

• Operational voltage limits. Defines an operating range of the input voltage using max_voltage and min_voltage. Using a hysteresis of reenable_voltage_offset, will set available torque to zero when out of range, and back to available torque when back in range.

• Motor efficiency effects. Employs a 2D lookup table to model efficiency as a function of speed and torque. Parameters eff_spd_vector, eff_torque_vector, and eff_table define the lookup table. Both electric current consumed and waste heat generated are computed using this lookup table at the operating point (i.e. speed and torque).

• Rotational inertia effects. Computes the torque needed to accelerate/decelerate the motor armature inertia, and removes/adds it from/to the shaft torque.

Assumptions:

• Friction losses of all kinds are neglected.

• Peak torque is only defined for one quadrant, but it is assumed it applies equally to all 4 quadrants.

• Efficiency map is only defined for one quadrant, but it is assumed it applies equally to all 4 quadrants.

• Motor and controller are considered a single unit in terms of efficiency losses and waste heat generation.

More information about the block.

• Parameters:

  • peak_power_watts. Peak power in Watts.

  • peak_torque_Nm. Peak torque in Newton meters.

  • peak_spd1_radps. Speed at which available starts decreasing to zero in radians per second.

  • peak_spd2_raps. Speed at which available starts reaches zero in radians per second.

  • min_voltage. System shuts down below this voltage..

  • max_voltage. System shuts down above this voltage..

  • reenable_voltage_offset. Hysteresis value for voltage threshold to prevent rapid switching..

  • eff_spd_vector. Efficiency map speed break points in radians per second

  • eff_trq_vector. Efficiency map torque break points in newton meters.

  • eff_table. Efficiency map table data.

  • inertia_kgm2. Rotational inertia of the motor armature in kg m^2.

• see parameter descriptions in the model.

• Inputs

  • mot_spd_radps. The instantaneous speed operating point of the motor, in radians per second.

  • mot_trq_req_norm. The requested torque to be produced by the motor. norm means normalized, so -1 <= mot_trq_req_norm <= 1.

  • mot_dc_voltage. The instantaneous direct current (DC) voltage applied to the motor input terminals, in Volts.

• Outputs

  • mot_trq_Nm. The instantaneous torque produced by the motor at its shaft, in Newton-meters.

  • mot_current_A. The instantaneous electric current consumed by the motor in Amps.

  • mot_heat_gen_pwr. The instantaneous thermal heat power being generated inside the motor and controller bodies. In units of Watts.

• Time mode: Hybrid. Continuous for everything except voltage limits, which is modeled as discrete behavior.

Gain Scheduling PID

Implements a discrete time PID controller with the following features:

• Feedforward port

• Inputs for gains Kp, Ki, Kd used for scheduling the gain as needed

• Initialize from external initial condition

• Reset to external initial condition

• Hold

• Anti-wind up

• Output limiting from external limits

More information about the block.

• Parameters

  • dt: The discrete step that the block is being executed at. Needed for correct calculation of integral and derivative.

• Inputs

  • ffwd. Feedforward inport

  • err. The measured error that the controller is meant to correct. e.g. X_target - X_measured.

  • kp, ki, kd. The gains

  • upper_limit, lower_limit. The external limits for output limiting.

  • reset. Boolean signal to trigger reset feature. If kept True, reset is continuously applied.

  • hold. Boolean signal to enable hold feature. Keep True to maintain hold.

  • ic. External initial condition.

Gearbox

Implements a fixed ratio mechanical gear box.

• Parameters

  • ratio. The conversion ration of the gearbox.

• Inputs

  • trq_in. Input or upstream torque.

  • spd_in. Input or upstream speed.

• Outputs

  • trq_out. Output or downstream torque.

  • spd_out. Output or downstream speed

• Time mode. Agnostic

High Voltage Battery

Implements a basic electro-chemical battery by means of coulomb counting, with the following features:

• Open circuit voltage (OCV) defined by 1D lookup table as function of SOC (state of charge).

• Closed loop voltage (CCV) computed as OCV - voltage_drop. Where voltage_drop is V=I*R, and R is the battery_internal_resistance in Ohms.

• Capacity parameter in kWh.

More information about the block.

• Parameters

  • battery_capacity_kWh. Energy capacity of the battery in kilo-Watt-hours.

  • battery_internal_resistance. Internal resistance in Ohms.

  • battery_initial_SOC. Initial state of charge.

  • soc2ocv_soc_vector. State of charge break points for SOC based open circuit voltage model.

  • soc2ocv_ocv_vector. Open circuit voltage data points for SOC based open circuit voltage model

• Inputs

  • pack_current_A. Electrical current flowing through the battery in Amps.

• Outputs

  • pack_V. The DC voltage of the battery.

• Time mode. Continuous

Multi Speed Transmission

Implements an automotive 5-speed automatic transmission. Controller modeled as basic input speed based state machine with debounced shift events to prevent rapid gear switching.

More information about the block.

• Parameters

  • ratio_1st, ... , ratio_5th. Ratios of the gears.

  • upshift_spd_thr. Input speed threshold causing upshift event.

  • downshift_spd_thr. Input speed threshold causing downshift event.

  • shift_action_debounce_thr. Minimum time between shift events in controller computation cycles.

  • gear_ratio_state_max. Upper limit of gear state variable.

  • gear_ratio_state_min. Lower limit of gear state variable.

• Inputs

  • input_trq_Nm. Input torque to the transmission in Newton meters.

  • output_spd_radps. Output speed of the transmission in radians per second.

• Outputs

  • output_trq_Nm. Output torque of the transmission in Newton meters.

  • input_spd_radps. Input speed of the transmission in radians per second.

• Time mode. Hybrid. The controller is modeled as discrete.