EMC of converters

Goals

formation-objectifs-seointro EMC of converters :

- Master critical EMC issues during the design and development of a converter

The aim of this training course is to:
- Understand how conducted and radiated disturbances are emitted by converters
- Understand, design and optimise different filter topologies
- Identify and make the best choices of topologies and components
- Diagnose the limitations and ‘faults’ of critical components
- Apply design tips to reduce EMC problems

Program

1/ Introduction

• The decibel scale


• Common and differential modes


• Narrowband frequency spectrum


• Spectral density of a pulse


• Detection modes and CISPR


• Fictitious networks (RSIL), Current clamp


• Civil, military and DO160 limits


• Specific features in aeronautics


• The 5 types of disturbances


• LF reactance chart


• The U.I. diagram

2/ Converter immunity

• Switch-on overvoltage


• Input protection


• Surge immunity standards


• Varistors and their implementation


• Protection of a PFC or boost


• Modelling of a shock wave


• Risks associated with optocouplers


• Routing of a control circuit


• Continuous/discontinuous conduction

3/ Power converters

• MC and MD of a Graetz bridge


• Power wave distortion


• Power and form factors


• Distortion meter and THD measurement


• Effects ofa PFC on EMC


• Autotransformer dodecaphase bridge


• Diode recovery


• Snubber/damper roles and calculation


• Switching losses and SOA


• Multi-level converters

4/ Common mode disturbances Calculation of a common mode disturbance Reduction of ‘hot’ capacitances

• CM currents on internal cable


• Common mode input to output


• Should outputs be floated?


• The three cases of input to output CM


• Shielded transformers


• Design of a wound shield


• Power supply without CM inductance


• Single-phase CM/MD separator


• Spectrum emitted before filtering


• MC insertion loss


• Choice of single/double cell filter


• MC of an H-bridge/mode conversion


• Saturation of an MC inductance


• Measurement and analysis methods


• Key points of EMC for a large converter


• Pitfalls of MC power supply filters


• MC cabling and optimisation

5/ Differential mode disturbances

• Impedance of a capacitor


• Calculating a disturbance in DC


• Impedance of inductance/capacitor


• Wiring and errors in an EMC filter


• Spectrum in DC before filtering


• Insertion loss and resonance in DC


• Choice of single/double cell


• Damping of an L-C in MD


• Filtering of a continuous bus


• MD induced by magnetic field


• Effects of RSIL 5 µH/50 µH


• Pitfalls of power supply filters in MD


• Noise reduction through multiphases


• Final MC + MD filter


• Analysis of a measured spectrum


• Optimal filtering of a small power supply

6/ Converter radiation

• E and H field radiation


• Small loop / small whip


• Power cable radiation


• Magnetic pot and LF radiation


• Risk of oscillation of an H-bridge


• HF radiation sources


• Noise reduction at source


• IGBT drivers or super-junctions


• Radiated emission traps


• Making a sensitive clamp


• Evaluating radiated emission


• Analysing and reducing emission

7/ Components and structures

• Skin effect of an alternating current wire


• Magnetic field and induction


• Micro- and micro-magnetic permeability


• Skin thickness in ferrite


• Measurement of permeability µ’ and µ’’


• Ferrites with high μ and nanocrystalline


• Saturation of a magnetic core


• Capacitance according to the winding method


• Compensated flux inductance (PFC)


• High voltage / Paschen curve


• Roles of an air gap and apparent µ


• Inductance measurement according to current


• Materials with distributed air gaps


• Amorphous material / ‘mag amp’ mag amp »


• Scalar measurements of a transformer


• Magnetic field in a transformer


• Leakage inductance / interlacing


• Additional copper losses


• Planar magnetic circuits


• Couplings between secondaries


• Capacitors connected in parallel


• Circuits on SMI


• Loss reduction / step-down


• Capacitive power supplies


• Choosing a differential probe


• Series/parallel resonance


• SPICE simulation in MD and MC