ABB ACS1000i air-cooled, User Manual

Page: 63 / 174

04 CONTROL SYSTEM
3BHS206977 E01 REV H ACS1000I AIR-COOLED USER MANUAL 63/174
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.
Figure 4-4: Direct torque control
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 66)
- Serial communication interface (fieldbus) for serial data transfer to a higher-level
control system (see “4.3.2 Serial communication interface (fieldbus)” on page 70)
- Pulse encoder interface NTAC (option) (see “4.3.3 Pulse encoder interface NTAC (option)”
on page 70)
(1) Torque reference
(2) Speed reference
(3) Actual reference
(4) Speed controller
(5) Torque reference controller
(6) Torque-flux comparator
(7) Motor model
(8) Switching logic
(9) Switch positions
(10)Voltage
(11)Current
(12)Motor
1
2
3
4
5 6
7
8
9
10
11
12