MAIN CIRCUIT Service Manual M4 - M10
29.12.1999 Page 70
8.3.4 Spare parts
Capasitors
Precharging resistors (Adapter board)
Detailed information for the spare parts is available from spare parts lists in
section “SPARE PART LIST”.
8.4 DC- to AC-converter (inverter)
8.4.1 Description
The three phase DC- to AC-converter (inverter) converts DC power to three
phase AC-power for the motor. IGBT bridge produces a symmetrical three
phase PWM (Pulse Width Modulated) AC voltage.
8.4.2 Operation
Sophisticated modulator asic circuit controls IGBT transistors which are
chopping DC voltage in a way that the output is three phase AC-system.
Carrier frequency is adjusted by parameter. Output voltage consist PWM
pulses and each pulse have amplitude of DC-link voltage. Pulse lengths are
depending on needed motor voltage.
8.4.3 Troubleshooting
Troubleshooting of IGBTs is described in the section 7.3.2.2.
8.4.4 Assembly instructions of IGBTs
IGBT is sensitive component for an electro static discharge (ESD) and shall be
handled in any phase of assembly in manner of safe ESD working. Wear
antistatic clothes, as well as antistatic shoes and wrist wrap connected to
GND for proper and safe discharging.
1. Clean heat sink from deteriorated thermal compound, a dust and all
particles on it. For the cleaning process, piece of cotton moistured with an
isopropanol based chemical can be used to cut grease and to make the
cleaning easier.
2. A mounting area on the heat sink has to be clean and a surface flat. If
bursts or damages on the surface exist, the heat sink should be rejected
and replaced with good one.
3. Clean a base plate of IGBT by clean piece of cotton, immersed in the
isopropanol.
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