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Kemppi OY
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-
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
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
voltage is approx. 540 V in normal operation conditions.
• Rectifier size is 80 A 1600 V
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
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
2.5. Power stage(IGBT)
• Topology of the power stage is traditional full bridge. The full bridge topology requires four power switches which are
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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