BMW I01 Product Information page 139

I01￿High-voltage￿Components
7.￿EKK
• Housing
• EKK￿control￿unit
• Three-phase￿current￿synchronous￿motor
• AC￿inverter
• Air￿conditioning￿compressor.
These￿individual￿components￿are￿never￿replaced￿separately￿￿The￿entire￿EKK￿is￿always￿replaced.￿At￿this
stage￿the￿tasks￿of￿some￿components￿are￿explained￿in￿order￿to￿better￿explain￿the￿function￿of￿the￿EKK.
7.2.1.￿EKK￿control￿unit
The￿EKK￿control￿unit￿controls￿the￿engine￿speed￿of￿the￿three-phase￿motor￿in￿the￿EKK￿based￿on￿the
requests￿of￿the￿IHKA￿and￿reports￿the￿operating￿status￿back￿to￿the￿IHKA￿control￿unit.￿The￿EKK￿control
unit￿communicates￿with￿the￿IHKA￿via￿the￿LIN￿bus.￿The￿IHKA￿is￿the￿master￿control￿unit￿for￿the￿EKK.
7.2.2.￿Three-phase￿current￿synchronous￿motor
A￿three-phase￿synchronous￿motor￿is￿used￿as￿the￿drive￿for￿the￿EKK.￿The￿energy￿is￿taken￿from￿the
high-voltage￿battery.￿The￿necessary￿three-phase￿current￿is￿converted￿in￿the￿EKK￿using￿an￿AC￿inverter
(DC/AC￿converter).￿The￿three-phase￿synchronous￿motor￿is￿operated￿in￿the￿engine￿speed￿range
between￿860￿and￿8600 rpm￿and￿is￿infinitely￿variable.￿It￿uses￿an￿electrical￿power￿of￿up￿to￿4.5 kW.￿The
maximum￿power￿is￿required,￿for￿example,￿at￿high￿ambient￿temperatures,￿high￿interior￿temperatures,
high￿temperatures￿of￿the￿high-voltage￿battery￿and￿low￿air￿flow￿of￿the￿cooling￿module.
7.2.3.￿AC￿inverter
The￿DC/AC￿converter￿converts￿the￿direct￿current￿voltage￿into￿the￿three-phase￿alternating￿current
that￿is￿required￿to￿operate￿the￿three-phase￿synchronous￿motor.￿The￿EKK￿control￿unit￿and￿the￿DC/
AC￿converter￿are￿integrated￿in￿the￿aluminium￿housing￿of￿the￿EKK￿and￿are￿cooled￿by￿the￿gaseous
refrigerant￿flowing￿past.￿If￿the￿temperature￿of￿the￿DC/AC￿converter￿exceeds￿125 °C,￿the￿high-voltage
supply￿is￿shut￿off￿by￿the￿EKK￿control￿unit.￿The￿attempt￿is￿made￿through￿different￿measures￿such￿as
speed￿increase￿for￿cooling￿initially￿not￿to￿allow￿the￿temperature￿to￿rise￿so￿high.￿The￿temperature￿is
monitored￿by￿the￿electric￿A/C￿compressor￿control￿unit.￿If￿the￿temperature￿drops￿below￿112 °C,￿the
EKK￿continues￿to￿run.
The￿supply￿voltage￿for￿EKK￿has￿a￿voltage￿range￿of￿about￿200 V￿to￿410 V.￿The￿power￿is￿reduced￿above
and￿below￿this￿voltage￿range￿or￿the￿EKK￿is￿switched￿off.
7.2.4.￿Air￿conditioning￿compressor
To￿compress￿the￿refrigerant,￿the￿spiral￿compressor￿(also￿known￿as￿the￿scroll￿compressor)￿is￿used.
R134a￿refrigerant￿is￿used￿for￿the￿US￿market.
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