Advanced Energy RFG 1251, User Manual

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2-2 Theory 5706058-A
Advanced Energy
®
Figure 2-1. RFG 1251 simplified block diagram
AC
In
Input
Auxiliary
Supply
Inverter
RF Module
Driver/Exciter
Power Amplifier
Output Tank/Filter
CEX/Interconnect
Measurement
System
Control &
Logic
Control
Interface
RF
Out
CEX Input
CEX Output
(1)
(2)
(3) (4)
(4A)
(4B)
(4C)
(4D)
(5)
(6)
Table 2-1. Block Diagram Explanation
(1) Input In the input section, 208 Vac, 3
φ
, line voltage is routed through a
circuit breaker and line filter to a 3
φ
contactor and the input of an
auxiliary supply (2). The contactor, when closed, delivers the line
voltage to a diode bridge, where it is rectified to 300 Vdc. The
300 Vdc bus is provided to the inverter section (3).
(2) Auxiliary Supply The auxiliary supply provides dc power to control and logic
circuits throughout the unit. Its switching design operates at
220 kHz and generates approximately 250 W of power at 30 Vdc,
24 Vdc, ±15 Vdc, and 5 Vdc. It also supplies limited 24 Vdc and
15 Vdc power to the Control connector for external use.
(3) Inverter The inverter provides variable-amplitude dc power to the RF
power amplifier (4). It consists of two assemblies: the phase
control card and the switch card.
The inverter uses MOSFET transistors as switches to convert the
300 Vdc bus from the input section to a variable 0 to 200 Vdc
signal. A 0 to 10 Vdc analog signal from the control section (6)
regulates the dc voltage. At full-rated power, this section must
supply up to 1700 W to the power amplifier (4B).