5.3.2 Sources of EMI
Modern Frequency converters (see illustration below) utilise IGBTs to provide an efficient and cost effective means to create
the Pulse Width Modulated (PWM) output waveform necessary for accurate motor control. These devices rapidly switch the
fixed DC bus voltage creating a variable frequency, and variable voltage PWM waveform. This high rate of voltage change
[dV/dt] is the primary source of the frequency converters generated EMI.
The high rate of voltage change caused by the IGBT switching creates high frequency EMI.
130BX137.10
AC Line
Rectifier
DC Bus
Inverter
Motor
Filter reactor
IGBT
Filter capacitor
PWM waveform
Sine wave
Illustration 5.1 F-frame Functionality Diagram
L11
L21
L31
L12
L22
L32
T1
T2
T3
130BX422.10
Filter capacitor
Filter reactor
Filter capacitor
Filter reactor
Rectifier
DC Bus
Inverter
AC Line
AC Line
Sine wave
IGBT
Motor
PWM waveform
Illustration 5.2 12-pulse Functionality Diagram
Frequency Converter and Mot...
High Power Service Manual for Modular F Frame Drives
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