Universal Motor
Universal (or serialised) motor with electrical and torque characteristics.
Description
The Universal Motor block simulates the electrical characteristics and torque of a universal (or serialised) motor using the following equivalent circuit:
In this circuit
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- armature winding resistance;
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- armature inductance;
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- resistance of the field winding;
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- field winding inductance.
If Model parameterization is set to By equivalent circuit parameters, the equivalent circuit parameters for this model are set. The Universal Motor block calculates the motor torque as follows:
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The magnetic field in the motor induces the following back EMF in the armature winding:
where is the proportionality constant and is the angular velocity.
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The mechanical power is equal to the power caused by the back EMF:
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Engine torque:
The torque to speed relationship for the universal motor model is related to the parameters in the diagram above. If Model parameterization is set to By DC rated power, rated speed & maximum torque or By DC rated power, rated speed & electrical power, the parameters of the equivalent circuit are calculated as follows:
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The parameter has no effect on the torque-speed dependence of the steady-state torque when using a DC source.
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The circuit voltages are summed:
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Solve the previous equation for and substitute this value into the equation for torque:
The unit uses the rated speed and power to calculate the rated torque. The unit uses the values for rated torque and rated speed in the previous equation plus the corresponding electrical power to determine the values and .
If Model parameterization is set to By AC rated power, rated speed, current & electrical power then the model must include the inductive terms and . This requires RMS rated current and voltage information for the total inductance.
The block models the motor inertia and damping for all values of the Model parameterization. The output torque is:
The unit generates a positive torque acting from the mechanical ports C to R.
Ports
Conserving
#
+
—
positive terminal
electricity
Details
A non-directional port connected to the positive terminal of the universal motor.
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-
—
negative terminal
electricity
Details
Non-directional port associated with the negative terminal of the universal motor.
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R
—
motor rotor
`rotational mechanics
Details
A mechanical non-directional port associated with the rotor of a universal motor.
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C
—
motor housing
`rotational mechanics
Details
A mechanical non-directional port associated with the housing of a universal motor.
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Hf
—
field winding heat port
heat
Details
Thermal port of the field winding.
Dependencies
To use this port, select the Enable thermal port checkbox.
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Ha
—
armature winding heat port
heat
Details
Thermal port of the armature winding.
Dependencies
To use this port, select the Enable thermal port checkbox.
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Parameters
Electrical Torque
#
Model parameterization —
block parameterization
By equivalent circuit parameters | By DC rated power, rated speed & maximum torque | By DC rated power, rated speed & electrical power | By AC rated power, rated speed, current & electrical power
Details
Select one of the following block parameterization methods:
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By equivalent circuit parameters- Set the electrical parameters for the equivalent circuit model of the motor. -
By DC rated power, rated speed & maximum torque- set the DC power and speed parameters that the unit converts to the equivalent circuit model. -
By DC rated power, rated speed & electrical power- set the AC rated power and speed parameters that the unit converts to a motor equivalent circuit model. -
By AC rated power, rated speed, current & electrical power- Set the AC rated power and speed parameters that the unit converts to a motor equivalent circuit model.
| Values |
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| Default value |
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| Program usage name |
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| Evaluatable |
No |
#
Total armature and field winding resistance —
total resistance of armature and field winding
Ohm | GOhm | MOhm | kOhm | mOhm
Details
Total resistance of armature and field winding.
Dependencies
To use this parameter, set Model parameterization to `By equivalent circuit parameters'.
| Units |
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
#
Back-emf constant —
counter-EMF coefficient
V/(A*rad/s)
Details
The ratio of the voltage generated by the motor to the motor speed.
Dependencies
To use this parameter, set the Model parameterization parameter to `By equivalent circuit parameters'.
| Units |
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
#
Rated speed (at rated load) —
nominal speed
rpm | deg/s | rad/s
Details
Motor rotation speed at rated mechanical power.
Dependencies
To use this parameter, set Model parameterization to By DC rated power, rated speed & maximum torque, By DC rated power, rated speed & electrical power or By AC rated power, rated speed, current & electrical power.
| Units |
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
#
Rated load (mechanical power) —
rated load
W | GW | MW | kW | mW | uW | HP_DIN
Details
The mechanical load for which the motor is designed at rated speed.
Dependencies
To use this parameter, set Model parameterization to `By DC rated power, rated speed & maximum torque', `By DC rated power, rated speed & electrical power' or `By AC rated power, rated speed, current & electrical power'.
| Units |
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
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Rated DC supply voltage —
rated DC supply voltage
V | MV | kV | mV
Details
The voltage for which the power rating is specified.
Dependencies
To use this parameter, set Model parameterization to By DC rated power, rated speed & maximum torque or By DC rated power, rated speed & electrical power.
| Units |
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
#
Maximum (starting) torque —
maximum torque
N*m | mN*m | lbf*ft
Details
The maximum torque generated by the motor.
Dependencies
To use this parameter, set Model parameterization to By DC rated power, rated speed & maximum torque.
| Units |
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
#
Electrical power in at rated load —
electrical power at rated mechanical power
W | GW | MW | kW | mW | uW | HP_DIN
Details
The amount of electrical power consumed by the motor at rated mechanical power.
Dependencies
To use this parameter, set Model parameterization to By DC rated power, rated speed & electrical power or By AC rated power, rated speed, current & electrical power.
| Units |
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
#
RMS rated voltage —
RMS nominal voltage
V | MV | kV | mV
Details
RMS supply voltage when the motor is operating on AC mains.
Dependencies
To use this parameter, set Model parameterization to `By AC rated power, rated speed, current & electrical power'.
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
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RMS current at rated load —
RMS current at rated load
A | MA | kA | mA | nA | pA | uA
Details
RMS current when the motor is operating on AC mains at rated load.
Dependencies
To use this parameter, set Model parameterization to `By AC rated power, rated speed, current & electrical power'.
| Units |
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
#
AC frequency —
AC frequency
Hz | GHz | MHz | kHz
Details
The frequency of the AC power supply.
Dependencies
To use this parameter, set Model parameterization to `By AC rated power, rated speed, current & electrical power'.
| Units |
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
#
Total armature and field winding inductance —
total inductance of armature and field winding
H | mH | nH | uH
Details
The total inductance of the armature and field winding. If the value of this inductance is not known, set a small non-zero number.
*Note
It is possible to set the Total armature and field winding inductance to zero, but this only makes sense if the motor is controlled from a DC source.
Dependencies
To use this parameter, set Model parameterization to `By equivalent circuit parameters', `By DC rated power, rated speed & maximum torque' or `By DC rated power, rated speed & electrical power'.
| Units |
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
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 a change in the rotational speed of the motor. The value can be zero.
| Units |
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
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Rotor damping —
rotor energy dissipation
N*m/(rad/s) | ft*lbf/(rad/s)
Details
Energy dissipated by the rotor. The value can be zero.
| Units |
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
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Initial rotor speed —
initial rotation speed
rpm | deg/s | rad/s
Details
Rotor rotation speed at the beginning of the simulation.
| Units |
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
Temperature Dependence
# Field to armature resistance ratio, Rf/Ra — resistance ratio of the field winding and armature winding
Details
The resistance ratio of the field winding to the armature winding. This parameter is only required when using armature and field winding thermal ports. It is used to determine the individual resistance values for the field and armature windings in order to properly distribute the heat generated by the two resistors.
Dependencies
To use this parameter, select the Enable thermal port checkbox.
| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
#
Resistance temperature coefficients, [alpha_f alpha_a] —
temperature coefficients of armature and rotor resistance
1/K | 1/degR | 1/deltaK | 1/deltadegC | 1/deltadegF | 1/deltadegR
Details
A 1 by 2 line vector containing the coefficients in the equation relating resistance to temperature. The first element corresponds to the field winding and the second element corresponds to the armature winding. By default, the values for copper are used.
Dependencies
To use this parameter, select the Enable thermal port checkbox.
| Units |
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
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Measurement temperature —
measuring temperature
K | degC | degF | degR | deltaK | deltadegC | deltadegF | deltadegR
Details
The temperature for which the motor parameters are determined.
Dependencies
To use this parameter, select the Enable thermal port checkbox.
| Units |
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
Thermal Port
# Enable thermal port — switching on the thermal ports
Details
Modelling of thermal effects.
To enable thermal effects modelling, set the parameter checkbox to `enabled'.
| Default value |
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| Program usage name |
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| Evaluatable |
No |
#
Thermal masses, [Mf Ma] —
thermal masses
J/K | kJ/K
Details
A 1 by 2 line vector containing thermal mass values for the field and armature windings.
Thermal mass is the energy required to raise the temperature by one degree.
Dependencies
To use this parameter, select the Enable thermal port checkbox.
| Units |
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
#
Initial temperatures, [T_field T_armature] —
initial temperatures
K | degC | degF | degR | deltaK | deltadegC | deltadegF | deltadegR
Details
A 1 by 2 line vector containing the temperature values of the excitation and armature thermal ports at the start of the simulation.
Dependencies
To use this parameter, select the Enable thermal port checkbox.
| Units |
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |