BMW i3 Inverter

BMW I3 inverter

BMW I3 inverter

Forum thread: https://openinverter.org/forum/viewtopic.php?p=23214#p23214

BMW i3™ inverter drop-in board Available

https://openinverter.org/shop/index.php?route=product/product&product_id=72

Overview

There are 2 variants of the i3, the standard i3 with motor power rated at 125kW and the i3s rated at 135kW.

There are 2 subvariants, as REX versions have an additional 25kw inverter and onboard generator.

Power stage: Infineon FS800R07 IGBTs rated for 800amps 650v

Openinverter Drop-in Board

Openinverter i3 drop-in board

The drop-in board houses the openinverter, generates 32V for the gate driver board, communicates via SPI with the gate driver board to obtain voltage and temperature readouts, and provides outputs to operate contactors.

As of 12 April 2024, the following mods are required to use these boards:

1. Check solder connections on the 40 pin surface mount Harwin connector to the gate driver board for dry joints or shorts
2. Apply code update in section below to prevent err_out pin on openinverter interfering with SPI communications
3. Pin 35 of the Harwin connector to the gate driver board is not connected to anything, but testing indicates this must be powered for the gate driver to work, at least on some boards. Voltage required at pin to be confirmed.

Pinouts for the three connectors on this board below.

Pinout for Ampseal Plug

Pin No	Assigniment	Description
1	12V
2	BRAKE_IN
3	PRECHARGE_OUT
4	CANL
5	CANH
6	DCSW_OUT
7	FORWARD_IN
8	REVERSE_IN
9	5V (OUT)
10	RESOLVER_S2/ENCODER_A	Sin Hi
11	GND
12	RESOLVER_S1	Sin Lo
13	THROTTLE1
14	THROTTLE2
15	RESOLVER_R1	Ex Hi
16	RESOLVER_S3/ENCODER_B	Cos Hi
17	MTEMP+
18	MTEMP-
19	RESOLVER_S4	Cos Lo
20	EMCYSTOP_IN
21	GND
22	RESOLVER_R2	Ex Lo
23	START_IN

Pinout for Gate Driver Board

Pin No	I/O	Description	Notes		Pin No	I/O	Description	Notes
1					21		GND Switching Mosfets ?
2	I	32V in			22		GND Switching Mosfets ?
3	I	32V in			23
4	I	IGBT A HI			24
5	I	IGBT A LOW			25
6	I	CS (ADC)			26		GND IGBT Driver ground
7	I	SDI			27		GND IGBT Driver ground
8	I	SDO			28		GND IGBT Driver ground
9	I	SCK			29		GND IGBT Driver ground
10	I	IGBT B HI			30		GND IGBT Driver ground
11	I	IGBT B LOW			31		GND IGBT Driver ground
12	I	IGBT C HI			32		GND IGBT Driver ground
13	I	IGBT C LOW			33		5V IGBT Driver Power
14					34		5V IGBT Driver Power
15					35	I	IGBT PSU 12V on
16	O	IGBT DRIVER UVW Upper Ready			36	O	IGBT Driver Fault
17	O	IGBT DRIVER UVW Lower Ready			37	I	5V LEM Current sensor Power
18	O	Current Sense C Signal			38		GND Current sensor Ground
19	O	Current Sense B Signal			39		GND Current sensor Ground
20	O	Current Sense A Signal			40		GND Current sensor Ground

Motor Resolver & Temperature Sensors

12-pin PCB header to connect to the motor sensors is an ERNI MiniBridge, part number 294920

Wire colours to pin allocation below determined by schematic and multimeter trace, with resolver coils and temperature sensors checked for resistance. Confirmed with motor bench test.

ERNI Minibridge Connector. Dots indicate pin 1.

Pinout for ERNI Microbridge

Pin No	Colour	Description	Notes
1	Brown	Sin Hi	Twisted pair. 22.4 - 33.6 Ω.
2	Blue	Sin Lo
3	Yellow	Ex Hi	Twisted pair. 22.4 - 33.6 Ω
4	Green	Ex Lo
5	Red	Cos Hi	Twisted pair. 13.6 - 20.4 Ω
6	White	Cos Lo
7	Blue	Temperature Sensor	From BMW Service Technical Training Manual - I01 High-voltage Components: There are two stator coil temperature sensors. The rotor temperature is determined using readings from the stator temperature sensors.
8	Grey
9	Red	Temperature Sensor
10	Grey
11	-	Unused	These wires terminate in one of the six pin connectors in the motor housing. There is nothing connected to them.
12	-	Unused

Motor Resolver & Temperature Sensor Adaptor Boards

ERNI Microbridge adapter board

Ampseal adapter board

A pair of adaptor boards (see images to right) are available and shipped with the current drop-in boards. These enable the ERNI Microbridge connector from the resolver to be connected to the required pins on the Ampseal connector. Design files for these boards will be posted on github at some point - if you need a copy in the meantime contact user 'CJW' or post on the i3 controller hacking thread. Code Update for Gate Driver Board - SPI Commication Code Update for Gate Driver Board - SPI Commication

Code Update for Gate Driver Board - SPI Commication

The BMW i3 gate driver board communicates the DC bus voltage (ie traction battery voltage) and IGBT heatsink temperatures to the Openinverter via SPI.

On the Openinverter mini mainboard, pin 17 on JP2 is normally used as an 'Error Output'. When used with the BMW i3, this pin must instead be used for the SPI Clock signal.

To avoid the clock signal being pulled high or low by the pin acting as an Error Output, find this section of code in vehiclecontrol.cpp:

//Brake pin is used as SPI_MISO
DigIo::brk_out.Configure(GPIOC, GPIO5, PinMode::INPUT_FLT);

and insert these lines of code below it, to disable the Error Output:

//Disable err_out so it doesn't pull the clock signal up or down
DigIo::err_out.Configure(GPIOC, GPIO10, PinMode::INPUT_FLT);

Openinverter Parameters

As of 12 April 2024, page 10 of the forum thread contains an initial set of parameters that were successfully used for bench testing a motor with a pair of lead acid car batteries. Will update and eventually post a full set of parameters here once the motor is properly set up and has been tested with a high voltage battery.

Future Development

List of tasks to be completed to enable full use of these motors:

1. Required voltage for pin 35 of Harwin gate driver board connector to be confirmed
2. Motor temperature sensor to be mapped and added to code
3. Design files for adaptor boards posted to github