Chapter 2 Product Information
ACH200 Series High Voltage Variable Frequency Speed Control System Operating Manual
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2.2 Operating Principle and System Component
2.2.1 System Working Principle
The ACH200 series of high voltage AC drive systems are "high-high", voltage-source AC
drives. The series H-bridge high voltage AC drive speed control system is based on an output of
6kV with 5 units per phase (for 10kV, 8 units per phase).
The 6kV grid voltage in the diagram feeds the phase shifting transformer directly, which has
15 separate three-phase low-voltage windings on the secondary side. Each three-phase low-voltage
winding feeds a low-voltage single-phase AC drive (called an H-bridge or power unit), whose circuit
diagram is shown in Figure 2-2. In the example given in Figure 2-2, each of the three phases output
to the motor is connected in series by five power units, making a total of 15 power units for the three
phases, resulting in a variable voltage, variable frequency power supply with three proportional and
adjustable voltages and frequencies. It can directly drive three-phase asynchronous motors up to 6
kV.
If a voltage of 10 kV is required, the number of power units in series per phase can be increased.
Control
system
A1
B1
C1
A2
B2
C2
An
Bn
Cn
Motor
Phase
shift
transfor
mers
50Hz 6kV
Power inlet cable
Figure.2-2
The power unit circuit consists mainly of the main circuit and the control circuit. The main
