ABB ACS1000 User Manual page 60

4.2.2.4 Direct torque control
The speed and torque of the motor is controlled by DTC (Direct Torque Control). DTC provides
accurate speed and torque control, and high dynamic speed response.
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Figure 4-5: Direct torque control
(1) Torque reference
(2) Speed reference
(3) Actual reference
(4) Speed controller
(5) Torque reference controller
(6) Torque-flux comparator
Switching of the semiconductors in the inverter is directly controlled in accordance with the
motor core variables flux and torque.
The measured motor currents and DC link voltages are inputs to an adaptive motor model. The
model produces exact values of torque and flux every 25 microseconds. Motor torque and flux
comparators compare the actual values to reference values which are produced by the torque
and flux reference controllers.
Depending on the outputs from the hysteresis controllers, the switching logic directly
determines the optimum switch positions every 50 microseconds and initiates switching
whenever required.
4.2.2.5 Peripheral I/O devices
The peripheral input and output devices connected to the AMC circuit board include:
- Local CDP control panel
- IOEC I/O modules for parallel signal transfer to external devices (see "4.3.1 IOEC I/O
modules" on page 61)
- Serial communication interface (fieldbus) for serial data transfer to a higher-level
control system (see "4.3.2 Serial communication interface (fieldbus)" on page 65)
- Pulse encoder interface NTAC (option) (see "4.3.3 Pulse encoder interface NTAC (option)"
on page 65)
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ACS1000 AIR-COOLED USER MANUAL
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(7) Motor model
(8) Switching logic
(9) Switch positions
(10)Voltage
(11) Current
(12)Motor
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