EMC of converters

Goals

The objectives of the training EMC of converters :

Mastering 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 aimed at reducing 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)
• Civil, military and DO160 limits
• Specific features in aeronautics
• The 5 types of disturbances
• LF reactance chart
• The U.I. plan


2 – Sources of disturbances in the converter
• Analysis of Buck or Half Bridge switching 
• Identification of critical loops in Buck
• Time simulation of disturbances
• Parameters influencing disturbances 
• Diode recovery
• Beware of parasitic elements
• Conduction type


3 – Self-interference of the control
• Emerging components
• Miller effects of SJ power MOSFETs
• Parallel connection of transistors
• Distortion of the PWM signal at the driver input
• Risk of linear optocouplers
• Equipotentiality of control circuits
• Active drivers


4– Immunity of converters
• Overvoltage at switch-on
• Risk of latch-up
• Surge immunity standards
• Varistors and their implementation
• Protection of a PFC or boost
• CTP and resettable fuses
• Tips for immunity


5 – Power converters
• Power and form factors
• Distortion meter and THD measurement
• Effects of a PFC on EMC
• Twelve-phase autotransformer bridge
• Roles and calculation of a snubber
• Multi-level converters


6 – Common mode disturbances
• Calculation of a CM disturbance
• Reduction of hot capacities
• CM currents on internal cable
• Input-to-output common mode
• Should outputs be floated?
• The 3 cases of input-to-output CM
• Internal shield transformers
• Choosing a wound CM shield
• CM-free power supply
• Single-phase CM/MD separator
• Spectrum emitted before filtering
• CM insertion loss
• Choosing single/double cell
• Common mode of an H bridge
• Saturation of a CM choke
• Measurement and analysis methods
• Common mode induced by H field
• Traps in MC power supply filters
• MC optimisation method


7 – Differential mode disturbances
• Impedance of a capacitor
• Calculation of an MD disturbance
• Cabling control
• Criticism of an EMC filter
• MD spectrum before filtering
• Common mode insertion loss
• Choice of single/double cell
• Common mode damping of an L-C
• Filtering on a DC bus
• Common mode induced by magnetic field
• Effects of RSIL 5 µH/50 µH
• Common mode power supply filter traps
• Noise reduction by multiphases
• Final MC + MD filter
• Influence of power supplied
• Optimal filtering of a small power supply
• Typical filtering and development of an EMC filter


8 – Radiation from converters
• E and H field radiation
• Small loop / small whip
• Radiation from the power cable
• Magnetic pot and LF radiation
• Risk of oscillation in an H bridge
• Sources and reduction of HF radiation
• Review of a converter layout
• Production of a sensitive clamp
• Evaluation of radiated emissions
• Methodology for reducing radiated emissions


9 - Components and structures
• Skin effect of an alternating current wire
• Magnetic field and induction
• Magnetic permeabilities µ' and µ''
• Saturation of a magnetic toroid
• Capacitance: Winding method
• Compensated flux inductance (PFC)
• High-voltage winding
• Roles of an air gap and apparent µ
• Materials with distributed air gaps
• Magnetic field in a transformer
• Leakage inductance / interlaced windings
• Couplings between secondaries
• Parallel capacitor connection
• Resonant converter


10 - Frequency simulation of conducted emissions
• Asymptotic method in energy conversion
• Common mode envelope generator
• Coupling and modelling of an MC converter
• MC emission simulation and filtering
• Differential mode envelope generator
• Coupling and modelling of an MD converter
• MD emission simulation and filtering


11 - Multiphysics modelling
• New challenges in converter design
• Multiphysics optimisation of converters
• Available tools
• Simulation/measurement comparisons