Rotational Inertia

Ideal mechanical rotational inertia

  • Library:
  • Powertrain Blockset / Drivetrain / Couplings

    Vehicle Dynamics Blockset / Powertrain / Drivetrain / Couplings

Description

The Rotational Inertia block implements an ideal mechanical rotational inertia.

Power Accounting

For the power accounting, the block implements these equations.

Bus Signal DescriptionVariableEquations

PwrInfo

PwrTrnsfrd — Power transferred between blocks

  • Positive signals indicate flow into block

  • Negative signals indicate flow out of block

PwrR

Mechanical power from base shaft

PTR

PTR= TRω

PwrC

Mechanical power from follower shaft

PTC

PTC= TCω

PwrNotTrnsfrd — Power crossing the block boundary, but not transferred

  • Positive signals indicate an input

  • Negative signals indicate a loss

PwrDampLoss

Power loss due to damping

Pd

Pd=b|ω|2

PwrStored — Stored energy rate of change

  • Positive signals indicate an increase

  • Negative signals indicate a decrease

PwrStoredShft

Rate change of stored internal torsional energy

Ps

Ps=ωω˙J

The equations use these variables.

TR

Input torque

TC

Output torque

ω

Driveshaft angular velocity

J

Rotational inertia

b

Rotational viscous damping

Pd

Power loss due to damping

Ps

Rate change of stored internal torsional energy

Ports

Input

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Applied input driveshaft torque, TR, in N·m.

Dependencies

To create this port, for Port Configuration, select Simulink.

Load driveshaft torque, TC, in N·m.

Dependencies

To create this port, for Port Configuration, select Simulink.

Angular velocity in rad/s. Torque is in N·m.

Dependencies

To create this port, for Port Configuration, select Two-way connection.

Rotational inertia, in kg·m^2.

Dependencies

To create the Inertia port, select External inertia input.

Output

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Bus signal containing these block calculations.

SignalDescriptionVariableUnits
Trq

R

Applied input driveshaft torque

TRN·m

C

Output driveshaft torque

TCN·m

Damp

Damping torque

Td=bω

N·m

Spd

Angular driveshaft speed

ωrad/s
PwrInfo

PwrTrnsfrd

PwrR

Mechanical power from base shaft

PTR

W
PwrC

Mechanical power from follower shaft

PTC

W

PwrNotTrnsfrd

PwrDampLoss

Power loss due to damping

Pd

W

PwrStored

PwrStoredShft

Rate change of stored internal torsional energy

Ps

W

Dependencies

To create this port, select Output Info bus.

Angular driveshaft speed, ω, in rad/s.

Dependencies

To create this port, for Port Configuration, select Simulink.

Angular velocity in rad/s. Torque is in N·m.

Dependencies

To create this port, for Port Configuration, select Two-way connection.

Parameters

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Block Options

Specify the port configuration.

Dependencies

Specifying Simulink creates these ports:

  • RTrq

  • CTrq

  • Spd

Specifying Two-way connection creates these ports:

  • R

  • C

Select to create the Info output port.

Dependencies

To create the Inertia port, select External inertia input.

Parameters

Rotational inertia, in kg·m^2.

Dependencies

To enable this parameter, clear Input rotational inertia.

Torsional damping, in N·m· s/rad.

Initial angular velocity, in rad/s.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Introduced in R2017a