Spellman SLM SERIES, Инструкция по эксплуатации

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SLM MANUAL 13 118073-001 Rev C
Chapter 4
P
RINCIPLES
O
F
O
PERATION
he SLM Series of high voltage power supplies
utilizes sophisticated power conversion technology.
Advanced analog and power conversion techniques
are used in the SLM series. The intention of the
Principles of Operation is to introduce the basic function
blocks that comprise the SLM power supply. For details
on a specific circuit, consult Spellman’s Engineering
Department.
The SLM power supply is basically an AC to DC power
converter. Within the power supply, conversions of AC
to DC then to high frequency AC, then to high voltage
DC take place.
Typical SLM power supplies comprise a few basic
building blocks. These are: 1) AC to DC rectifier, 2)
Power Factor correction boost circuitry 3) High frequency
quasi-resonant inverter, 4) High voltage transformer and
rectifier circuits, and 5) Control and monitoring circuits.
The following is a brief description of each building
block.
4.1 Power Factor and Associated
Circuits
The SLM series can operate from 90 - 265Vac, for the
300Watt model and 180 –264Vac for the 600 and
1200Watt models. The input voltage is connected via a
typical IEC 320 type input connector. An internal EMI
filter and fuse housing is an integral part of the SLM
module. The input circuits actively correct the power
factor.
The input line voltage is applied to a current limit device
to reduce the initial inrush current. The input line voltage
is converted to a 400Vdc voltage via an active PFC
Converter.
WARNING
The energy levels used and generated by the
power supply can be lethal! Do not attempt to
operate the power supply unless the user has a
sufficient knowledge of the dangers and hazards
of working with high voltage. Do not attempt to
approach or touch any internal or external
circuits or components that are connected or
have been connected to the power supply. Be
certain to discharge any stored energy that may
be present before and after the power supply is
used. Consult IEEE recommended practices for
safety in high voltage testing #510-1983.
4.2 High Frequency Inverter
The SLM is a resonant converter operating in a zero
current switching, series resonant, parallel loaded
topology. MOSFET transistors switch the 400 Vdc
voltage to the resonant tank circuit. Typical operating
frequency is in the range of 35-65 KHz depending on
model. Control of the resonant circuit output is done by
the low voltage control circuits, and are isolated by an
isolated pulse transformer. The output of the resonant
circuit is applied to the primary of the high voltage
transformer.
4.3 High Voltage Circuits
The high voltage transformer is a step-up type. The
secondary of the high voltage transformer is connected to
the high voltage output circuit. The output circuit will
vary depending upon the rated output voltage and a full
wave Cockroft-Walton multiplier is used. A feedback
signal is generated by the high voltage resistor divider.
This feedback signal is sent to control circuits to provide
voltage regulation and monitoring. A current sense
resistor is connected at the low voltage end of the output
circuit. The circuit sense signal is sent to the control
circuits to provide current regulation and monitoring.
The high voltage output is connected to the output
limiting resistors. These resistors limit the peak surge
current in the event an arc or discharge occurs. The
limiting resistor output is connected to the output
connector provided.
WARNING
THE HVPS IS DESIGNED TO HANDLE AN
ARC RATE OF 1 ARC PER SECOND,
EXCEEDING 1 ARC PER SECOND COULD
CAUSE DAMAGE TO THE HVPS. HVPS
FAILURE CAUSED BY EXCESSIVE ARC
WILL NOT BE COVERED UNDER THE
WARRANTY
.
T