Generic Linear Actuator

A universal linear actuator powered by a constant voltage source or a PWM driver.

blockType: AcausalElectricPowerSystems.Electromechanical.MechatronicActuators.GenericLinear

Path in the library:

/Physical Modeling/Electrical/Electromechanical/Mechatronic Actuators/Generic Linear Actuator

Description

Block Generic Linear Actuator implements a model of a universal linear actuator designed for control from a constant voltage source or a PWM driver. Determine the force-velocity characteristics in the form of tabular values for powering the motor at rated voltage. This functionality allows you to simulate an engine without resorting to an equivalent circuit.

The architecture of a motor or drive determines how electrical losses depend on force. For example, in a DC motor, losses are proportional to the square of the current. Since force is proportional to current, losses are also proportional to mechanical force. In most engines, electrical losses are proportional to the square of the mechanical force. Block Generic Linear Actuator calculates this loss value using the provided parameters Motor efficiency (percent) and Speed at which efficiency is measured.

Some engines also have a loss factor that is independent of power. An example is a shunt motor in which the field winding consumes direct current regardless of the load. Parameter Force-independent electrical losses takes this effect into account.

Engine EFFICIENCY is the mechanical power divided by the sum of the mechanical power and both electrical losses. The block assumes that the speed at which the efficiency of the engine is determined is in the motor quadrant and, therefore, is positive.

You can use the unit in the opposite direction by changing the sign of the applied voltage. For example, the block H-Bridge changes the direction of rotation of the motor if the voltage at the REV port is greater than the Reverse threshold voltage parameter. However, if you use the block in the opposite direction, then the data is specified «Strength is speed» to work in the forward direction:

Positive forces and positive speeds in the motor quadrant;
Positive force and negative velocities in the counterclockwise generation quadrant;
Negative force and positive velocity in the generating quadrant clockwise.

Thermal effects of the model

A thermal port can be opened to simulate the effects of losses during the conversion of energy into heat. To open the thermal port, select the checkbox for the Enable thermal port option.

Assumptions and limitations

Curve Data «Strength is speed» They correspond only to the rated voltage, so the unit produces accurate results only at plus or minus rated voltage.
The unit requires to be provided with force velocity data for the entire range in which the drive is used. To use the drive in the generation and braking areas, provide additional data outside the normal driving area.
The behavior of the model is sensitive to force-velocity data. For example, the idle speed is correctly determined and is finite only when the data intersects the speed axis.
To manage a block from a block H-Bridge:
- Do not place any other blocks between the block H-Bridge and a block Generic Linear Actuator.
- In the dialog box of the block H-Bridge set the Freewheeling mode parameter to Via one semiconductor switch and one freewheeling diode. Choice Via two freewheeling diodes It does not set the output voltage of the bridge to zero when the input PWM signal is low.
- In the dialog boxes of the blocks H-Bridge, Generic Linear Actuator and Controlled PWM Voltage make sure that the value Simulation mode the same for all three blocks.

Variables

Use the parameter group Initial Targets to set the priority and initial target values for the block parameter variables before modeling. For more information, see Configuring physical blocks using target values.

Ports

Conserving

# + — positive terminal
electricity

Details

A non-directional port associated with the positive terminal of the drive.

Program usage name

p

# - — negative terminal
electricity

Details

Non-directional port associated with the negative terminal of the drive.

Program usage name

n

# R — piston
`rotational mechanics

Details

A mechanical non-directional port associated with a piston.

Program usage name

rod_flange

# C — hull
`rotational mechanics

Details

A mechanical non-directional port associated with the actuator housing.

Program usage name

case_flange

# H — heat port
heat

Details

Heat port.

Dependencies

To use this port, select the Enable thermal port checkbox.

Program usage name

thermal_port

Parameters

Electrical Force

# Speed values — vector of velocity values
m/s | mm/s | cm/s | km/s | m/hr | km/hr | in/s | ft/s | mi/s | ft/min | mi/hr | kn

Details

A vector of velocity values for constructing an interpolation table of the correspondence of force and velocity values.

Units	`m/s` \| `mm/s` \| `cm/s` \| `km/s` \| `m/hr` \| `km/hr` \| `in/s` \| `ft/s` \| `mi/s` \| `ft/min` \| `mi/hr` \| `kn`
Default value	`[-15.0, -10.0, -5.0, 0.0, 5.0, 10.0, 15.0, 20.0, 25.0, 30.0] m/s`
Program usage name	`velocity_vector`
Evaluatable	Yes

# Force values — vector of force values
N | nN | uN | mN | kN | MN | GN | dyn | lbf | kgf

Details

A vector of force values for constructing an interpolation table of the correspondence of force and velocity values.

Units	`N` \| `nN` \| `uN` \| `mN` \| `kN` \| `MN` \| `GN` \| `dyn` \| `lbf` \| `kgf`
Default value	`[4.0, 3.5, 3.0, 2.5, 2.0, 1.5, 1.0, 0.5, 0.0, -0.5] N`
Program usage name	`force_vector`
Evaluatable	Yes

# Rated voltage — Rated voltage
V | uV | mV | kV | MV

Details

Specify the voltage for which the device being modeled is designed.

Units	`V` \| `uV` \| `mV` \| `kV` \| `MV`
Default value	`12.0 V`
Program usage name	`V_rated`
Evaluatable	Yes

# Motor efficiency (percent) — Engine EFFICIENCY

Details

The efficiency that the unit uses to calculate power-dependent electrical losses.

Default value	`70.0`
Program usage name	`efficiency`
Evaluatable	Yes

# Force-independent electrical losses — force-independent electrical losses
W | uW | mW | kW | MW | GW | V*A | HP_DIN

Details

Fixed electrical losses associated with the drive when the force is zero.

Units	`W` \| `uW` \| `mW` \| `kW` \| `MW` \| `GW` \| `V*A` \| `HP_DIN`
Default value	`2.0 W`
Program usage name	`P_loss_base`
Evaluatable	Yes

# Simulation mode — Simulation mode
PWM | Averaged

Details

If set for the parameter Simulation mode meaning PWM, then it is necessary to apply a PWM signal to the electrical terminals of the unit, switching between zero and rated voltage. The current consumed from the power grid is equal to the amount needed to transfer mechanical energy and compensate for electrical losses. If the applied voltage exceeds the rated voltage, the resulting force increases proportionally. However, applying a voltage other than the rated voltage may give unrepresentative results.

If set for the parameter Simulation mode meaning Averaged, then the force that arises in response to the applied voltage will be equal to:

where — the value of force at speed . The current consumed from the power supply is such that the product of the current strength and it is equal to the average power consumption.

Values	`PWM` \| `Averaged`
Default value	`PWM`
Program usage name	`simulation_mode`
Evaluatable	No

# Speed at which efficiency is measured — the speed at which efficiency is measured
m/s | mm/s | cm/s | km/s | m/hr | km/hr | in/s | ft/s | mi/s | ft/min | mi/hr | kn

Details

The speed that the unit uses to calculate power-dependent electrical losses.

Units	`m/s` \| `mm/s` \| `cm/s` \| `km/s` \| `m/hr` \| `km/hr` \| `in/s` \| `ft/s` \| `mi/s` \| `ft/min` \| `mi/hr` \| `kn`
Default value	`20.0 m/s`
Program usage name	`velocity_reference_for_efficiency`
Evaluatable	Yes

Mechanical

# Plunger mass — piston weight
kg | mg | g | t | lbm | oz | slug

Details

The mass of the moving part of the motor. The value can be zero.

Units	`kg` \| `mg` \| `g` \| `t` \| `lbm` \| `oz` \| `slug`
Default value	`0.1 kg`
Program usage name	`mass`
Evaluatable	Yes

# Linear damping — linear damping
N*s/m | kgf*s/m | lbf*s/ft | lbf*s/in

Details

Linear damping. The value can be zero.

Units	`Ns/m` \| `kgfs/m` \| `lbfs/ft` \| `lbfs/in`
Default value	`1e-5 N*s/m`
Program usage name	`damping`
Evaluatable	Yes

Temperature Dependence

Details

Temperature coefficient of resistance.

Dependencies

To enable this option, check the box next to the Enable thermal port option.

Units	`1/K` \| `1/degR` \| `1/deltaK` \| `1/deltadegC` \| `1/deltadegF` \| `1/deltadegR`
Default value	`0.00393 1/K`
Program usage name	`alpha`
Evaluatable	Yes

Details

The temperature for which the drive parameters are defined.

Dependencies

To enable this option, check the box next to the Enable thermal port option.

Units	`K` \| `degC` \| `degF` \| `degR` \| `deltaK` \| `deltadegC` \| `deltadegF` \| `deltadegR`
Default value	`25.0 degC`
Program usage name	`T_measurement`
Evaluatable	Yes

Thermal Port

# Enable thermal port — turning on the heat port

Details

Modeling of thermal effects.

To enable the simulation of thermal effects, set the option checkbox to enabled.

Default value	`false (switched off)`
Program usage name	`has_thermal_port`
Evaluatable	No

# Thermal mass — thermal mass
J/K | kJ/K

Details

Thermal mass is the energy required to raise the temperature by one degree.

Dependencies

To enable this option, check the box next to the Enable thermal port option.

Units	`J/K` \| `kJ/K`
Default value	`100.0 J/K`
Program usage name	`thermal_mass`
Evaluatable	Yes