Implement direct torque and flux control (DTC) induction motor drive model
The DTC Induction Motor Drive (AC4) block represents an improved scalar control drive for induction motors with direct torque and flux control. This drive features closed-loop speed control using hysteresis-band torque and flux controllers. The speed control loop outputs the reference electromagnetic torque and stator flux of the machine. The torque and flux references are compared with their estimated values, respectively, and the errors are fed to hysteresis-band controllers. The outputs of the hysteresis-band controllers are then used to obtain the required gate signals for the inverter through an optimal switching table.
The main advantage of this drive compared to other scalar-controlled drives is its improved dynamic response. This drive can reduce the impact of torque variation on the flux and conversely through an optimal switching table. Therefore, this drive is less sensitive to the inherent coupling effect (between the torque and flux) present in the machine. However, this drive requires similar signal processing as in vector-controlled drives, which makes its implementation complex compared to closed-loop Volts/Hertz controlled drives.
Electrical™ Specialized Power Systems software, the DTC Induction Motor Drive
block is commonly called the
AC4 motor drive.
The DTC Induction Motor Drive block uses these blocks from the Electric Drives / Fundamental Drive Blocks library:
Speed Controller (AC)
Direct Torque Controller
The model is discrete. Good simulation results have been obtained with a 2 µs time step. In order to simulate a digital controller device, the control system has two different sampling times:
The speed controller sampling time
The D.T.C. controller sampling time
The speed controller sampling time has to be a multiple of the D.T.C. sampling time. The latter sampling time has to be a multiple of the simulation time step.
Select how the output variables are organized. If you select
output buses (default), the block has three separate output buses for motor,
converter, and controller variables. If you select
bus, all variables output on a single bus.
Select between the load torque, the motor speed, and the mechanical rotational port as
mechanical input. Default is
If you select and apply a load torque, the output is the motor speed according to the following differential equation that describes the mechanical system dynamics:
This mechanical system is included in the motor model.
If you select the motor speed as mechanical input, then you get the electromagnetic torque as output, allowing you to represent externally the mechanical system dynamics. The internal mechanical system is not used with this mechanical input selection and the inertia and viscous friction parameters are not displayed.
For the mechanical rotational port, the connection port S counts for the mechanical input and output. It allows a direct connection to the Simscape environment. The mechanical system of the motor is also included in the drive and is based on the same differential equation.
When you select this check box, the
Ctrl measurement outputs use the signal names to identify the bus
labels. Select this option for applications that require bus signal labels to have only
When this check box is cleared (default), the measurement output uses the signal definition to identify the bus labels. The labels contain nonalphanumeric characters that are incompatible with some Simulink® applications.
The Rectifier section of the Converters and DC Bus tab displays the parameters of the Rectifier block of the Fundamental Blocks (powerlib) library. For more information on the rectifier parameters, refer to the Universal Bridge reference page.
The DC bus capacitance (F). Default is
The braking chopper resistance used to avoid bus over-voltage during motor
deceleration or when the load torque tends to accelerate the motor (Ω). Default is
The braking chopper frequency (Hz). Default is
The dynamic braking is activated when the bus voltage reaches the upper limit of the
hysteresis band. The following figure illustrates the braking chopper hysteresis logic.
The dynamic braking is shut down when the bus voltage reaches the lower limit of the
hysteresis band. Default is
310. The Chopper hysteresis logic is shown
The Inverter section of the Converters and DC Bus tab displays the parameters of the Inverter block of the Fundamental Blocks (powerlib) library. For more information on the inverter parameters, refer to the Universal Bridge reference page.
This parameter allows you to choose between speed and torque regulation. Default is
Select hysteresis or space vector modulation. The default modulation type is
When you click this button, a diagram illustrating the speed and current controllers schematics appears.
The maximum change of speed allowed during motor acceleration (rpm/s). An excessively
large positive value can cause DC bus under-voltage. This parameter is used in speed
regulation mode only. Default is
The maximum change of speed allowed during motor deceleration (rpm/s). An excessively
large negative value can cause DC bus overvoltage. This parameter is used in speed
regulation mode only. Default is
The speed measurement first-order low-pass filter cutoff frequency (Hz). This
parameter is used in speed regulation mode only. Default is
The speed controller sampling time (s). The sampling time must be a multiple of the
simulation time step. Default is
The speed controller proportional gain. This parameter is used in speed regulation
mode only. Default is
The speed controller integral gain. This parameter is used in speed regulation mode
only. Default is
The maximum negative demanded torque applied to the motor by the current controller
(N.m). Default is
The maximum positive demanded torque applied to the motor by the current controller
(N.m). Default is
The torque hysteresis bandwidth. This value is the total bandwidth distributed
symmetrically around the torque set point (N.m). Default is
following figure illustrates a case where the torque set point is
Te* and the torque hysteresis bandwidth is set to dTe.
The stator flux hysteresis bandwidth. This value is the total bandwidth distributed
symmetrically around the flux set point (Wb). Default is
following figure illustrates a case where the flux set point is
ψ* and the torque hysteresis bandwidth is set to dψ.
This bandwidth can be exceeded because a fixed-step simulation is used. A rate transition block is needed to transfer data between different sampling rates. This block causes a delay in the gate signals, so the current may exceed the hysteresis band.
The desired initial stator flux established before the DTC drive module begins to
produce an electromagnetic torque. This flux is produced by applying a constant voltage
vector at the motor terminals (Wb). Default is
The DTC controller sampling time (s). The sampling time must be a multiple of the
simulation time step. Default is
The maximum inverter switching frequency (Hz). Default is
Click to show or hide the parameters of the Autotuning Control tool.
Specify the damping factor used for the calculation of the Kp and Ki gains of the
speed controller. Default is
Specify the desired settling time of the speed controller. This is time required for
the controller response to reach and stay within a 5 percent range of the target value.
Specify the ratio between the bandwidth and natural frequency. Default is
Compute the Proportional gain and Integral gain parameters of the Speed Controller (AC) block. The computation is based on the Desired damping [zeta], Desired response time @ 5%, and Bandwidth ratio (InnerLoop/SpeedLoop) parameters. The computed values are displayed in the mask of the Drive block. Click Apply or OK to confirm them.
The speed or torque set point. The speed set point can be a step function, but the speed change rate will follow the acceleration / deceleration ramps. If the load torque and the speed have opposite signs, the accelerating torque will be the sum of the electromagnetic and load torques.
The mechanical input: load torque (Tm) or motor speed (Wm). For the mechanical rotational port (S), this input is deleted.
A, B, C
The three phase terminals of the motor drive.
The mechanical output: motor speed (Wm), electromagnetic torque (Te) or mechanical rotational port (S).
When the Output bus mode parameter is set to Multiple output buses, the block has the following three output buses:
The motor measurement vector. This vector allows you to observe the motor's variables using the Bus Selector block.
The three-phase converters measurement vector. This vector contains:
The DC bus voltage
The rectifier output current
The inverter input current
Note that all current and voltage values of the bridges can be visualized with the Multimeter block.
The controller measurement vector. This vector contains:
The torque reference
The speed error (difference between the speed reference ramp and actual speed)
The speed reference ramp or torque reference
When the Output bus mode parameter is set to Single output bus, the block groups the Motor, Conv, and Ctrl outputs into a single bus output.
3 HP Drive
200 HP Drive
Drive Input Voltage
Motor Nominal Values
 Bose, B. K. Modern Power Electronics and AC Drives. Upper Saddle River, NJ: Prentice-Hall, 2002.
 Grelet, G. and G. Clerc. Actionneurs électriques. Paris: Éditions Eyrolles, 1997.
 Krause, P. C. Analysis of Electric Machinery. New York: McGraw-Hill, 1986.