Main Circuit Card Z001; Emi Filtering; Three Phase Rectifier V6; Turn-On Transient Suppression - Kemppi FASTMIG X 450 Service Manual

2. MAIN CIRCUIT CARD Z001

Main circuit card Z001 is a power stage module which is controlled by gate driver card A001. Machine power compo-
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nents primary rectifier and igbt module is mounted in main circuit card.

2.1. EMI filtering

Capacitors (C2-C8, C13, C14) and inductors (L1, L2) form an EMI-filter. The filter is divided into two sections. One part
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of the filter is a three-phase filter and it is located before the main rectifier. The other part is a one-phase filter and it
is located in DC-link circuit after the rectifier. The purpose of the filter circuit is to reduce conducted EMI to utility
network below limits specified in the norm EN50199. Resistors (R11-R13) discharge capacitors C2-C4 when then the
power source is switched off

2.2. Three phase rectifier V6

The three-phase rectifier unit (V6) rectifies the mains voltage (~ 400V) to DC-link voltage. Mean value of the DC-link
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voltage is approx. 540 V in normal operation conditions.
Rectifier size is 80 A 1600 V
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2.3. Turn-on transient suppression

The primary choke limits the inrush current to the DC-link capacitors while the mains switch is turned on. The purpose
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of the diode (V7) is to prevent voltage from rising above mains voltage. Without diode (V7) DC-link voltage could rise
too high due to the resonance circuit formed of the primary choke and DC-link capacitors

2.4. Current transformer (T1)

Current transformer T1 has turns ratio of 200:1 and it scales the primary current down for the control circuitry
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2.5. Power stage(IGBT)

Topology of the power stage is traditional full bridge. The full bridge topology requires four power switches which are
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implemented using IGBT module (V1). Switching frequency of the power switches is 20 kHz.
IGBT size is 4 x 150 A 1200 V
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SERVICE MANUAL
FASTMIG X
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