BMW I01, Информация о продукте

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I01�High-voltage�Components
12.�Technical�Safety�Precautions
174
3 The�voltage�in�the�high-voltage�circuit�is�increased�continuously
4 The�contacts�of�the�switch�contactors�are�fully�closed.
The�high-voltage�electrical�system�is�mainly�checked�by�the�EME�control�unit�and�the�SME�control
unit.�Criteria�relevant�for�safety,�for�example�the�circuit�of�the�high-voltage�interlock�loop�or�the�isolation
resistance,�are�checked.�Functional�preconditions�such�as�the�operating�readiness�of�all�subsystems
must�also�be�fulfilled�for�starting.
As�the�high-voltage�circuit�capacitors�have�high�capacity�values�(link�capacitors�in�the�power
electronics),�the�contacts�of�the�electromechanical�switch�contactors�cannot�be�easily�closed.
Extremely�high�current�pulses�would�damage�both�the�high-voltage�battery�and�the�link�capacitors
and�the�contacts�of�the�switch�contactors.�First�of�all,�the�switch�contactor�of�the�ground�cable�in�the
high-voltage�battery�is�closed.�In�order�to�restrict�the�switch-on�current,�there�is�a�current�path�with
resistance�in�the�positive�wire�(connected�parallel�to�the�switch�contactor).�This�is�now�activated�and
a�switch-on�current�restricted�by�the�resistance�charges�the�link�capacitors.�If�the�voltage�of�the�link
capacitors�has�reached�the�approximate�value�of�the�battery�voltage,�the�last�contact�of�the�switch
contactor�at�the�positive�terminal�of�the�high-voltage�battery�unit�is�closed.�The�high-voltage�system�is
now�fully�operational.
If�there�is�no�fault�in�the�high-voltage�system,�the�entire�starting�of�the�high-voltage�system�is
completed�in�about�0.5�seconds.�There�is�thus�no�disadvantage�for�the�customer�in�comparison�to
vehicles�with�a�conventional�engine.
The�SME�control�unit�communicates�successful�starting�via�the�PT-CAN2�to�the�EME�control�unit.
Fault�statuses�are�also�communicated�in�the�same�way,�if,�for�example,�a�contact�of�a�switch�contactor
was�unable�to�be�closed.
12.2.2.�Shutting�off�the�high-voltage�system
When�it�comes�to�shutting�off�the�high-voltage�system�a�distinction�is�made�between�regular�shut-
off�and�fast�shut-off.�The�regular�shutdown�described�here�protects�all�respective�components�on�the
one�hand,�and,�on�the�other�hand,�includes�the�monitoring�of�components�of�the�high-voltage�system
which�are�relevant�for�safety.
Regular�shutdown
If�the�following�preconditions�or�criteria�are�present,�the�high-voltage�system�is�shutdown�in�the�regular
manner:
• Terminal�15�is�switched�off�by�the�driver�and�the�after-running�period�is�expired�(controlled�by
EME)
• End�of�the�functions�"stationary�cooling",�"auxiliary�heater"�or�"conditioning�of�the�high-
voltage�battery"
• End�of�the�charging�procedure�for�the�high-voltage�battery.
The�sequence�for�the�regular�shutdown�is�generally�the�same�irrespective�of�the�trigger.�The�individual
steps�are:
1 EME�orders�the�shutdown�after�the�after-running�period�has�expired�via�bus�signals�at�the�PT-
CAN/PT-CAN2