Engee documentation

Generic Rotary Actuator

Universal rotary actuator controlled from a DC voltage source or PWM driver.

generic rotary actuator

Description

The Generic Rotary Actuator unit implements a universal rotary actuator model designed to be controlled from a DC voltage source or PWM driver. Define torque-speed characteristics as tabulated values to supply the motor at rated voltage. This functionality allows the motor to be modelled without referring to an equivalent circuit.

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

Some motors also have a loss factor that is independent of torque. An example is a shunt motor, where the field winding draws a constant current regardless of the load. The Torque-independent electrical losses parameter takes this effect into account.

The Motor 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 motor efficiency is determined is in the motor quadrant and is therefore positive.

It is possible to operate the block in the opposite direction by changing the sign of the applied voltage. For example, the H-Bridge block reverses the direction of motor rotation if the voltage on the REV port is greater than the Reverse threshold voltage parameter. However, if the unit is used in the reverse direction, specify the torque-speed data for forward operation:

  • Positive torques and positive speeds in the motor quadrant;

  • Positive torques and negative velocities in the counterclockwise generation quadrant;

  • Negative torques and positive velocities in the clockwise generating quadrant.

Thermal effects of the model

You can open the thermal port to model the effects of losses in the conversion of energy to heat. To open the thermal port, select the Enable thermal port checkbox.

Assumptions and limitations

  • The torque-speed curve data corresponds to nominal voltage only, so the block only produces accurate results at plus or minus nominal voltage.

  • This block must provide torque data for the entire range in which the drive is used. To use the drive in the generation and braking region, provide additional data outside the normal motion region.

  • The behaviour of the model is sensitive to torque-speed data. For example, the idle speed is correctly defined and is only finite when the data crosses the velocity axis.

  • To operate the unit from the H-Bridge unit:

    • Do not place any other blocks between the H-Bridge block and the Generic Rotary Actuator block.

    • In the H-Bridge block dialogue box, set the Freewheeling mode parameter to Via one semiconductor switch and one freewheeling diode. Selecting Via two freewheeling diodes does not set the bridge output voltage to zero when the input PWM signal is low.

    • In the H-Bridge, Generic Rotary Actuator and Controlled PWM Voltage block dialogues, make sure that the Simulation mode value is the same for all three blocks.

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 — rotor
`rotational mechanics

Details

A mechanical non-directional port associated with a rotor.

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 Torque

# Speed values — velocity vector
rpm | deg/s | rad/s

Details

Vector of velocity values to build an interpolation table of torque and velocity values.

Values

rpm | deg/s | rad/s
Default value

[-1500.0, -1000.0, -500.0, 0.0, 500.0, 1000.0, 1500.0, 2000.0, 2500.0, 3000.0] rpm
Program usage name

angular_velocity_vector
Evaluatable

Yes

# Torque values — vector of torque values
N*m | mN*m | lbf*ft

Details

A vector of torque values to build an interpolation table of torque and speed values.

Values

N*m | mN*m | lbf*ft
Default value

[0.04, 0.035, 0.03, 0.025, 0.02, 0.015, 0.01, 0.005, 0.0, -0.005] N*m
Program usage name

torque_vector
Evaluatable

Yes

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

Details

Specify the voltage for which the device to be modelled is designed.

Values

V | MV | kV | mV
Default value

12.0 V
Program usage name

V_rated
Evaluatable

Yes

# Motor efficiency (percent) — motor efficiency

Details

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

Default value

80.0
Program usage name

efficiency
Evaluatable

Yes

# Speed at which efficiency is measured — the speed at which the efficiency is measured
rpm | deg/s | rad/s

Details

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

Values

rpm | deg/s | rad/s
Default value

2000.0 rpm
Program usage name

angular_velocity_reference_for_efficiency
Evaluatable

Yes

# Torque-independent electrical losses — fixed electrical losses
W | GW | MW | kW | mW | uW | HP_DIN

Details

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

Values

W | GW | MW | kW | mW | uW | HP_DIN
Default value

0.1 W
Program usage name

P_loss_base
Evaluatable

Yes

# Simulation mode — simulation mode
PWM | Averaged

Details

If you set Simulation mode to PWM, apply a PWM signal to the unit’s electrical terminals, switching between zero and nominal voltage. The current drawn from the mains supply is equal to the amount required to transfer mechanical power and compensate for electrical losses. If the applied voltage exceeds the nominal voltage, the resulting torque increases proportionally. However, applying a voltage other than the rated voltage may give unrepresentative results.

If you set the Simulation mode parameter to `Averaged', the torque produced in response to the applied voltage will be equal:

ω

where ω is the torque value at the speed of ω . The current drawn from the power supply is such that the product of the current and is equal to the average power consumption.

Values

PWM | Averaged
Default value

PWM
Program usage name

simulation_mode
Evaluatable

No

Mechanical

# Rotor inertia — rotor inertia
g*cm^2 | kg*m^2 | lbm*ft^2 | lbm*in^2 | slug*ft^2 | slug*in^2

Details

The resistance of the rotor to the change of motion of the motor. The value can be zero.

Values

g*cm^2 | kg*m^2 | lbm*ft^2 | lbm*in^2 | slug*ft^2 | slug*in^2
Default value

0.0001 kg*m^2
Program usage name

J
Evaluatable

Yes

# Rotor damping — rotor damping
N*m/(rad/s) | ft*lbf/(rad/s)

Details

Rotor damping. The value can be zero.

Values

N*m/(rad/s) | ft*lbf/(rad/s)
Default value

1e-8 N*m/(rad/s)
Program usage name

damping
Evaluatable

Yes

Temperature Dependence

# Resistance temperature coefficient — temperature coefficient of resistance
1/K | 1/degR | 1/deltaK | 1/deltadegC | 1/deltadegF | 1/deltadegR

Details

Temperature coefficient of resistance.

Dependencies

To enable this parameter, select the Enable thermal port check box.

Values

1/K | 1/degR | 1/deltaK | 1/deltadegC | 1/deltadegF | 1/deltadegR
Default value

0.00393 1/K
Program usage name

alpha
Evaluatable

Yes

# Measurement temperature — measuring temperature
K | degC | degF | degR | deltaK | deltadegC | deltadegF | deltadegR

Details

The temperature for which the drive parameters are defined.

Dependencies

To enable this parameter, select the Enable thermal port check box.

Values

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 — switching on the heat port

Details

Modelling of thermal effects.

To enable thermal effects modelling, set the parameter 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 parameter, select the Enable thermal port checkbox.

Values

J/K | kJ/K
Default value

100.0 J/K
Program usage name

thermal_mass
Evaluatable

Yes