Chapter 2 - Operation Basics; Operation Of Isu; Main Circuit Diagram; Control - ABB ACS 600 User Manual

Operation of ISU

Main Circuit Diagram

Supply network
I
u
U
0

Control

Voltage Waveform

ACA 635 IGBT Supply Sections
The ISU is a four-quadrant switching-mode converter. The a.c. current
of the ISU is nearly sinusoidal at a unity power factor. In addition, the
power flow through the converter is reversible. As a default, the ISU
controls the DC link voltage to the peak value of the line-to-line voltage.
The DC voltage reference can be set also higher by a parameter.
A diagram of the main circuit of the IGBT supply is shown below.
AC choke
U
U
1 2
The control and modulation is based on the Direct Torque Control
(DTC) method typically used in ACS 600 motor control. Two line
currents and DC link voltage are measured and used for the control.
The control boards are similar to the boards of the inverter.
The high frequency switching and high du/dt slightly distorts the
voltage waveform at the input of the converter. The depth of the
voltage notches depends on the ratio of network inductance to total line
inductance (network + AC choke inductance).
Chapter 2 – Operation Basics
Control and Gate Drivers
Converter
Common DC bus
I
dc
U
c
2-1