bonitron M3460R, Руководство для пользователей

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Doc.# 993014
07/25/2000
3. Description of Operation
3.1 Ride-Thru Module
The M3460R Ride-Thru module consists of three basic sections as described below.
These basic sections are the Rectifier section, Boost Converter section, and Control Power Supply section.
3.1.1 Rectifier Section
This section converts the 3-phase AC line to a nominal DC bus. The Rectifier section contains the fusing,
diode bridge, DC bus filter capacitors and precharge circuitry for each stage of the module. Upon
application of power, Ride-Thru module precharge will commence charging the primary bus capacitors
through their precharge resistors. When the DC bus reaches its proper level, the Boost Converter section
will be ready to supply power to the DC bus on demand. When the Boost Converter section is needed, the
Precharge SCR modules are turned on which provides a path around the precharge resistors.
3.1.2 Boost Converter Section
The Boost Converter section will regulate the DC bus voltage during line dip conditions to a factory pre-set
level. Under normal line conditions, the input AC power will be rectified and fed through resistors around
the precharge SCR modules to the primary filter capacitors. If the AC line voltage dips, the precharge SCR
modules turn on and the Boost Converter section becomes active to regulate the bus voltage. An internal
pot establishes this voltage. The voltage is sensed and regulated by the 3460C1 control board and pumped
up by an IGBT chopper circuit for each stage of the Ride-Thru module. Each chopper circuit includes 1 DC
bus inductor, 1 current sensor, and 1 IGBT chopper transistor. If the DC bus level drops, the IGBT chopper
transistor is turned on and the DC bus inductor is connected between the primary DC bus and the negative
bus. The inductor current increases and energy is stored in the inductor until a maximum current is reached.
At this point the transistor is turned OFF and the energy is transferred to the drive DC bus. Each of the DC
chopper circuits is phase shifted from the others by 90 degrees to minimize peak current demands.
The boost chopper will switch as fast as needed to keep the DC bus at the preset level. When the maximum
switching frequency is reached, the DC bus will drop. When the DC bus drops below 450VDC, the run
relay will drop out and the bus chopper will stop switching. An over-voltage condition on the DC bus
(approximately 800VDC) will cause the Ride-Thru section to shut down. The Ride-Thru section will be re-
enabled once the DC bus voltage drops below approximately 760VDC.
If a chopper circuit output fuse should fail, an LED on its corresponding 3460F3 Fuse Detector will light,
and the Ride-Thru Ready signal will turn
OFF indicating a fault. The Ride-Thru will continue to operate at
75% load in this fault condition.
3.1.3 Control Power Supply Section
Control power is derived from the DC bus via the 3460D4 DC-DC power supply board. Voltage for the
DCS interface is derived from the 3460T4 Terminal board, and "backed up" by an isolated supply on the
3460D4 board. All control voltages are maintained under all specified dip conditions.