Modelica.Mechanics.Rotational.Sources

Information

This package contains ideal sources to drive 1D mechanical rotational drive trains.

Package Content

Name	Description
Position	Forced movement of a flange according to a reference angle signal
Speed	Forced movement of a flange according to a reference angular velocity signal
Accelerate	Forced movement of a flange according to an acceleration signal
Move	Forced movement of a flange according to an angle, speed and angular acceleration signal
Torque	Input signal acting as external torque on a flange
Torque2	Input signal acting as torque on two flanges
LinearSpeedDependentTorque	Linear dependency of torque versus speed
QuadraticSpeedDependentTorque	Quadratic dependency of torque versus speed
ConstantTorque	Constant torque, not dependent on speed
ConstantSpeed	Constant speed, not dependent on torque
TorqueStep	Constant torque, not dependent on speed

Modelica.Mechanics.Rotational.Sources.Position

Information

The input signal phi_ref defines the reference angle in [rad]. Flange flange is forced to move according to this reference motion relative to flange support. According to parameter exact (default = false), this is done in the following way:

1. exact=true
   The reference angle is treated exactly. This is only possible, if the input signal is defined by an analytical function which can be differentiated at least twice. If this prerequisite is fulfilled, the Modelica translator will differentiate the input signal twice in order to compute the reference acceleration of the flange.
2. exact=false
   The reference angle is filtered and the second derivative of the filtered curve is used to compute the reference acceleration of the flange. This second derivative is not computed by numerical differentiation but by an appropriate realization of the filter. For filtering, a second order Bessel filter is used. The critical frequency (also called cut-off frequency) of the filter is defined via parameter f_crit in [Hz]. This value should be selected in such a way that it is higher as the essential low frequencies in the signal.

The input signal can be provided from one of the signal generator blocks of the block library Modelica.Blocks.Sources.

Parameters

Name	Description
useSupport	= true, if support flange enabled, otherwise implicitly grounded
exact	true/false exact treatment/filtering the input signal
f_crit	if exact=false, critical frequency of filter to filter input signal [Hz]

Connectors

Name	Description
flange	Flange of shaft
support	Support/housing of component
phi_ref	Reference angle of flange with respect to support as input signal [rad]

Modelica.Mechanics.Rotational.Sources.Speed

Information

The input signal w_ref defines the reference speed in [rad/s]. Flange flange is forced to move relative to flange support according to this reference motion. According to parameter exact (default = false), this is done in the following way:

1. exact=true
   The reference speed is treated exactly. This is only possible, if the input signal is defined by an analytical function which can be differentiated at least once. If this prerequisite is fulfilled, the Modelica translator will differentiate the input signal once in order to compute the reference acceleration of the flange.
2. exact=false
   The reference angle is filtered and the second derivative of the filtered curve is used to compute the reference acceleration of the flange. This second derivative is not computed by numerical differentiation but by an appropriate realization of the filter. For filtering, a first order filter is used. The critical frequency (also called cut-off frequency) of the filter is defined via parameter f_crit in [Hz]. This value should be selected in such a way that it is higher as the essential low frequencies in the signal.

The input signal can be provided from one of the signal generator blocks of the block library Modelica.Blocks.Sources.

Parameters

Name	Description
useSupport	= true, if support flange enabled, otherwise implicitly grounded
exact	true/false exact treatment/filtering the input signal
f_crit	if exact=false, critical frequency of filter to filter input signal [Hz]

Connectors

Name	Description
flange	Flange of shaft
support	Support/housing of component
w_ref	Reference angular velocity of flange with respect to support as input signal [rad/s]

Modelica.Mechanics.Rotational.Sources.Accelerate

Information

The input signal a defines an angular acceleration in [rad/s2]. Flange flange is forced to move relative to flange support with this acceleration. The angular velocity w and the rotation angle phi of the flange are automatically determined by integration of the acceleration.

The input signal can be provided from one of the signal generator blocks of the block library Modelica.Blocks.Sources.

Parameters

Name	Description
useSupport	= true, if support flange enabled, otherwise implicitly grounded

Connectors

Name	Description
flange	Flange of shaft
support	Support/housing of component
a_ref	Absolute angular acceleration of flange with respect to support as input signal [rad/s2]

Modelica.Mechanics.Rotational.Sources.Move

Information

Flange flange is forced to move relative to flange support with a predefined motion according to the input signals:

    u[1]: angle of flange
    u[2]: angular velocity of flange
    u[3]: angular acceleration of flange

The user has to guarantee that the input signals are consistent to each other, i.e., that u[2] is the derivative of u[1] and that u[3] is the derivative of u[2]. There are, however, also applications where by purpose these conditions do not hold. For example, if only the position dependent terms of a mechanical system shall be calculated, one may provide angle = angle(t) and set the angular velocity and the angular acceleration to zero.

The input signals can be provided from one of the signal generator blocks of the block library Modelica.Blocks.Sources.

Parameters

Name	Description
useSupport	= true, if support flange enabled, otherwise implicitly grounded

Connectors

Name	Description
flange	Flange of shaft
support	Support/housing of component
u[3]	Angle, angular velocity and angular acceleration of flange with respect to support as input signals

Modelica.Mechanics.Rotational.Sources.Torque

Information

The input signal tau defines an external torque in [Nm] which acts (with negative sign) at a flange connector, i.e., the component connected to this flange is driven by torque tau.

The input signal can be provided from one of the signal generator blocks of Modelica.Blocks.Sources.

Parameters

Name	Description
useSupport	= true, if support flange enabled, otherwise implicitly grounded

Connectors

Name	Description
flange	Flange of shaft
support	Support/housing of component
tau	Accelerating torque acting at flange (= -flange.tau) [N.m]

Modelica.Mechanics.Rotational.Sources.Torque2

Information

The input signal tau defines an external torque in [Nm] which acts at both flange connectors, i.e., the components connected to these flanges are driven by torque tau.

The input signal can be provided from one of the signal generator blocks of Modelica.Blocks.Sources.

Connectors

Name	Description
flange_a	Flange of left shaft
flange_b	Flange of right shaft
tau	Torque driving the two flanges (a positive value accelerates the flange) [N.m]

Modelica.Mechanics.Rotational.Sources.LinearSpeedDependentTorque

Information

Model of torque, linearly dependent on angular velocity of flange.
Parameter TorqueDirection chooses whether direction of torque is the same in both directions of rotation or not.

Parameters

Name	Description
useSupport	= true, if support flange enabled, otherwise implicitly grounded
tau_nominal	Nominal torque (if negative, torque is acting as load) [N.m]
TorqueDirection	Same direction of torque in both directions of rotation
w_nominal	Nominal speed [rad/s]

Connectors

Name	Description
flange	Flange of shaft
support	Support/housing of component

Modelica.Mechanics.Rotational.Sources.QuadraticSpeedDependentTorque

Information

Model of torque, quadratic dependent on angular velocity of flange.
Parameter TorqueDirection chooses whether direction of torque is the same in both directions of rotation or not.

Parameters

Name	Description
useSupport	= true, if support flange enabled, otherwise implicitly grounded
tau_nominal	Nominal torque (if negative, torque is acting as load) [N.m]
TorqueDirection	Same direction of torque in both directions of rotation
w_nominal	Nominal speed [rad/s]

Connectors

Name	Description
flange	Flange of shaft
support	Support/housing of component

Modelica.Mechanics.Rotational.Sources.ConstantTorque

Information

Model of constant torque, not dependent on angular velocity of flange.
Positive torque acts accelerating.

Parameters

Name	Description
useSupport	= true, if support flange enabled, otherwise implicitly grounded
tau_constant	Constant torque (if negative, torque is acting as load) [N.m]

Connectors

Name	Description
flange	Flange of shaft
support	Support/housing of component

Modelica.Mechanics.Rotational.Sources.ConstantSpeed

Information

Model of fixed angular velocity of flange, not dependent on torque.

Parameters

Name	Description
useSupport	= true, if support flange enabled, otherwise implicitly grounded
w_fixed	Fixed speed [rad/s]

Connectors

Name	Description
flange	Flange of shaft
support	Support/housing of component

Modelica.Mechanics.Rotational.Sources.TorqueStep

Information

Model of a torque step at time .
Positive torque acts accelerating.

Parameters

Name	Description
useSupport	= true, if support flange enabled, otherwise implicitly grounded
stepTorque	Height of torque step (if negative, torque is acting as load) [N.m]
offsetTorque	Offset of torque [N.m]
startTime	Torque = offset for time < startTime [s]

Connectors

Name	Description
flange	Flange of shaft
support	Support/housing of component