Ametek California Instruments MX15 Series User Manual page 110

5.7.1 PFC Input Power Converter
The PFC section is located at the bottom of each power module. AC power enters the power
module at the PFC input section. The PFC section using a PWM boost converter to turn the
unregulated three phase 140 V AC into a regulated ± 225 V DC bus. A bank of capacitors is
used to provide ride-through and to support high peak current demands from the amplifier
boards. The PFC PWM circuit drives a set of three high capacity IGBT's. These IGBT's connect
directly to the DC bus bars, which connect the PFC output to the Amplifier boards.
The condition of the PFC section is constantly monitored and reported to the system interface
board. If the DC bus goes out of acceptable operating range, a fault is generated. Furthermore,
in any of the three AC input phases fails, the MX will shut itself down.
5.7.2 Modulator Board
The modulator board is located directly above the PFC board and next to the four board
Amplifier stack. The modulator board accepts an oscillator output reference signal as input and
drives the four amplifier boards using a high frequency PWM technique. The modulator has the
ability to drive the amplifiers in either parallel or series configuration, thus producing either a high
(300 Vac ./ 400 Vdc) or low (150 Vac / 200 Vdc) output voltage range.
The modulator contains several feedback loops that control the current sharing and output
regulation of the four power amplifier boards. The Modulator boards connect to the System
interface through a 50 pin ribbon cable located at the left front of the power module.
5.7.3 Amplifier Boards
The Amplifier boards are each attached to a heat sink and stacked on top of each other at the
top portion of the power module enclosure. Sets of two boards are held together by a bracket
which screws into the back wall of the power module enclosure. Power to each amplifier board
is supplied from the PFC section through a set of DC bus bars. Each amplifier board connects
to the modulator board via a small ribbon cable. Each Amplifier board has four outputs (A+. A-,
B+ and B-). These four outputs connect to a set of Inductor boards using stranded wires with
Anderson style connectors. The connection between the Amplifier boards and the Inductor
boards is specific and should not be reversed or damage could result. The output wire
connectors of each amplifier board are color coded to help identify the correct connections. The
connections between the Modulator board and the Amplifier boards are one to one. (Connectors
line up with amplifier boards).
The layout of the Amplifier board is shown in Figure 5-5.
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