ABB ACS850 series, Hardware Manual

Page: 22 / 120

Operation principle and hardware description
22
Motor control
The motor control is based on direct torque control. Two phase currents and DC link
voltage are measured and used for the control. The third phase current is measured
for earth fault protection.
Product overview
The ACS850-04 is an air-cooled IP20 drive module for controlling AC motors. It is to
be installed into a cabinet by the customer.
The ACS850-04 is available in several frame sizes depending on output power. All
frame sizes use the same control unit (type JCU).
Component Description
Braking chopper Conducts the energy generated by a decelerating motor from the DC bus to a
braking resistor. The braking chopper is built in the ACS850-04; braking
resistors are external options.
Braking resistor Dissipates the regenerative energy by converting it to heat.
Capacitor bank Energy storage which stabilizes the intermediate circuit DC voltage.
du/dt filter See page 99 .
Inverter Converts the DC voltage to AC voltage and vice versa. The motor is controlled
by switching the IGBTs of the inverter.
Mains choke See page 91 .
EMC filter See page 93 .
Rectifier Converts the three-phase AC voltage to DC voltage.