Pfc Boost Control Circuitry - Kemppi Kempact 253R Service Manual

3.2.3.6. PFC Boost control circuitry

PFC control circuitry is located on the primary side. Auxliary transformer T003 supplies operating voltage for the PFC
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control circuitry. The output voltage of the T003 is first rectified and then linear regulator is used to regulate auxiliary
voltage to 15V. PFC control IC N1 regulates DC-link voltage to approximately 370V
3.3. Main circuit diagram 253-, 323-models
3.3.1. Main circuit card Z001
3.3.1.1. EMC filter
Capacitors C5 - C7, C8 - C10, C19 - C21 and inductors T4 and L1 form an EMC filter
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First part of the filter is three phase filter which is located before the three phase rectifier V2
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Second part is DC filter (L1) which is located after three phase rectifier
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3.3.1.2. Inrush current limiting
PTC resistor R1 limits inrush current when the power source is switched on
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R1 is bypassed with relays K1 and K2 after DC link capacitors C17, C18 have been charged
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Relays K1 and K2 are controlled with the microcontroller
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3.3.1.3. IGBT driver
IGBT driver consists of gate transformers T2 and T3 and surrounding components
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3.3.1.4. Current transformer T1
Current transformer T1 is monitoring primary current and stops power stage operation if current is raising too high
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3.3.1.5. Main circuit
Main circuit topology is H-bridge. The H-bridge topology requires four power switches which are implemented using
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IGBT module V2. The switching frequency of the H – bridge is 20 kHz
253 power source uses 50A module
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323 power source uses 75A module
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Approx .. + 570 V
G1 G2
U
U
G1
G2
U
T1
G3 G4
U U
G3 G4
When IGBT-transistors G1 and G4 conduct, there is a positive voltage U
transistors G2 and G3 conduct there is a negative voltage U
Kemppi Oy
IGBT timings (PWM).
U
G1
U
G2
G5
U
G3
L1
U
G4
U U
G5 L1
U
T1
U
G5
U
L1
in main transformer primary. Power is adjusted by changing the
T1
SERVICE MANUAL
KEMPACT RA_V_1.2
in main transformer T1 primary and when IGBT-
T1
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