Power electronics in electric cars Prof. Dr. Pavol Bauer, Delft - PowerPoint PPT Presentation

Power electronics in electric cars Prof. Dr. Pavol Bauer, Delft University of Technology Image credits go here

Learning objectives What is a power electronic converter? • Power converter types: • AC or DC o Power flow direction o Isolation o Power converters in an electric car • Four quadrant power converter operation •

Power electronic converter A power electronic converter is an electronic device made of high power semiconductor switches that uses different switching states to change the magnitude and waveform of the voltage and current between the input and output. Power flow i in i o V in INPUT V o OUTPUT control signals

Power electronic switch Image Source: https://www.vfds.com/blog/switching-it-up-igbt

Power converter: AC and DC 1. DC-DC converter Direct Current (DC) 2. DC-AC converter (or) inverter 3. AC-DC converter (or) rectifier 4. AC-AC converters Alternating Current (AC)

Power electronic converter 2. Bidirectional 1. Unidirectional Power flow Power flow i in i o i in i o V in V in V o V o control signals control signals

Power electronic converter 1. Magnetically Isolated 2. Non-isolated Rectifier Inverter

Power converter Type AC or DC AC-DC DC-AC DC-DC AC-AC Magnetic Isolation Isolated Non-isolated Bidirectional power Bidirectional Unidirectional flow

Power converters in electric car Motor drive Auxiliary battery Battery On-board converter converter charger

Power converters in electric car Battery converter, Bidirectional 12V/48V Auxiliary supply On-board charger, Unidirectional Unidirectional converter for converter auxiliary 1 or 3 Phase AC Supply

Power converter Converter AC or DC Isolation Direction On-board charger AC-DC Isolated Unidirectional Battery converter DC-DC Isolated Bidirectional Isolated / Motor drive DC-AC Bidirectional Non-Isolated Auxillary battery Isolated / DC-DC Unidirectional converter Non-Isolated

Four quadrant operation Speed Driving Braking (Forward) 2 1 (Forward) Torque Driving 4 3 Braking (Reverse) (Reverse)

First quadrant operation Speed Driving 1 2 (Forward) Torque Torque 4 3 Rotation speed

Third quadrant operation Speed 2 1 Torque 3 Torque Driving 4 Rotation speed (Reverse)

Third quadrant operation Speed Braking 2 1 (Forward) Torque Torque 3 4 Rotation speed

DC Motor and motor drive operation Current magnitude à Torque magnitude Current direction à Torque direction Voltage magnitude à Rotation speed magnitude Voltage polarity à Rotation speed direction Torque Rotation speed

Four quadrant operation Bidirectional power flow can be achieved by controlling the polarity of voltage and/or current: Voltage, Speed Voltage Speed Current Torque Quadrant + + + + 1 2 1 + + - - 2 Current, 3 4 Torque - - - - 3 - - + + 4

AC and motor drive operation • AC motors more complicated than DC motors • Reverse rotation by changing the connection of the phases • Torque and speed control through control of AC voltage magnitude and frequency Torque Rotation speed

Power electronics in electric cars Prof. Dr. Pavol Bauer, Delft university of Technology Image credits go here