SIL 19­EP­16
April, 2016
Page 1 of 6
SUBJECT:

DPIM Component Overview, Gaskets, Screw Torques

MODELS AFFECTED:

H 40/50 EPTM Transmissions

Introduction:
The Dual Power Inverter Module 2 (DPIM2) converts energy from a DC source (ESS) into three­phase AC that
powers the H 40/50 EPTM Drive Unit motors. During conditions such as regenerative braking, the DPIM2 converts
the AC power from the Drive Unit motors back to DC to charge the ESS.

Internal Component Overview:
Integral to the DPIM2 are many electronic circuit boards and components that control the power electronics as well
as monitor the system and process inputs and outputs.
Bias Control Assembly (BCA) Circuit Cards
At the heart of the DPIM2 are two (2) BCA cards, one for each inverter. The primary function of the
BCA card is to control the SKiM® modules in the DPIM2. The BCA cards also communicate on the CAN
with other controllers, including the TCM and VCM, process the sensor data from the Drive Unit (speed
and motor temperature) and current sensors, and monitor the High Voltage Interlock Loop circuit.
SKiM® Modules
There are six (6) SKiM® modules in the DPIM2, three (3) for each inverter. Each SKiM® module consists
of a gate drive circuit card, capacitors, the insulated­gate bipolar transistors (IGBTs), and a heat sink.
Gate Drive Circuit Cards
The primary function of the gate drive card is to control the on/off switching of the IGBTs. The gate drive
cards work with the BCA card to control the inverter.
Insulated­Gate Bipolar Transistors (IGBTs)
The IGBTs are the primary electrical components that convert the DC power into AC power and vice
versa. There are six (6) IGBTs in each SKiM® module for throughput. The IGBTs quickly switch
between positive and negative DC voltage to create an AC voltage to power the Drive Unit motors. The
IGBTs also convert the AC voltage back into DC voltage when the Drive Unit motors are acting as
generators. The high frequency switching of the IGBTs generates heat that dissipates through the heat
sink and is carried away by transmission fluid.

ML / SL7812EN

3163438

Copyright © 2016 Allison Transmission, Inc. All Rights Reserved.

SIL 19­EP­16
April, 2016
Page 2 of 6
High Voltage Interlock Loop (HVIL) Circuit Card
The primary function of the HVIL card is to monitor the high voltage interlock loop, a series of switches
in the H 40/50 EPTM components, to ensure that no access covers are removed where potentially
hazardous electrical energy may exist. The HVIL card also reports the incoming DC voltage from
the ESS to the BCA cards.
Signal Interface and Encoder Circuit Cards
The DPIM2 contains one (1) common 24­way signal interface card and two (2) 32­way encoder cards,
one for each inverter. The 24­way signal interface card distributes the main 12V power and grounds,
DPIM2 wake up and torque control signals, and the CAN interface to each of the inverters. The 32­ way
encoder cards pass the speed sensor and RTD output signals from the Drive Unit to the BCA cards.
Current Sensors
The DPIM2 contains six (6) current sensors, three (3) for each inverter, and one (1) for each AC
phase. The current sensors measure the current flow and direction through the AC bus bars between
the SKiM® modules and the Drive Unit motors. The sensor data is sent directly to the BCA card for
the respective inverter.
Passive Discharge Resistor
The DPIM2 contains one (1) passive discharge resistor located under the HVIL circuit card on the
inverter B side of the DPIM2. The passive discharge resistor dissipates stored electrical energy, in the
form of heat, in the absence of active discharge.
The DPIM2 also contains a bank of large DC capacitors in the center located under the main DC bus bars.
The DC link bus bars connect to the main DC bus bars through a choke. The main DC bus bars, laminated in
white insulation, connect to the SKiM® modules. The AC link busbars attach to the SKiM® modules and to
the main AC bus bars.

DPIM Service Note Regarding Water Intrusion:
Both DPIM1 and DPIM2 contain a number of electronic circuit boards that control the inverter, communicate with
other components, and collect data from sensors in the H 40/50 EP hybrid system. As with any other electronic
devices such as smartphones, laptop computers, or tablet devices, the DPIM1 and DPIM2 are sensitive to water
which can create electrical shorts on any of the electronic components in the DPIM. Care must be taken to
ensure the DPIM is protected from water intrusion.
It is important to replace gaskets on the DPIM1 and DPIM2 when the DPIM is serviced or removed/installed.
Table 1 includes a reference to gasket part numbers and Figure 1 shows some of these gaskets. Refer to Parts
Catalog PC3717 for more information.
• AC and DC lug box cover gaskets should be replaced each time the lug box covers are removed.
• The DPIM2 main cover gasket should be replaced each time the main cover is removed for internal service.
• The single­use gasket on all three (3) high voltage cable connections to the DPIM1 and DPIM2 should be
replaced each time the cable flange is removed.
• The encoder and signal interface gaskets should be replaced each time they are removed from the DPIM2
housing.
• The gasket between the DC lug box and DPIM2 housing should be replaced when serviced.
• The gaskets between the two AC chokes and DPIM2 housing should be replaced when removed for service.

Copyright © 2016 Allison Transmission, Inc. All Rights Reserved.

SIL 19­EP­16
April, 2016
Page 3 of 6
Table 1. DPIM2 Gaskets (See Figure 1)
Description

P/N

Quantity

DPIM Main Cover

29540714

1

AC Lug Box Cover

29540715

2

DC Lug Box Cover

29540614

1

Signal Interface

29540711

1

Encoders

29540712

2

DC Lug Box to Housing

29540615

1

AC Choke to Housing

29540716

2

When replacing any of the gaskets on the DPIM, it is important to install the hollow EMI gaskets properly and
carefully to avoid damaging the new gasket. It is recommended to work the gasket into the cleaned groove in
a motion perpendicular to the groove to avoid stretching or compressing the gaskets. Installing the gasket in a
parallel motion to the groove risks stretching and ripping the hollow gasket which can result in an improper fit in
the groove. It is not acceptable to seat the gasket into the groove using the cover and tightening the screws. Do
not use a smooth socket or extension to roll the gasket into the groove. See Figure 2 for examples of improper
gasket installation.
Screw installation torque is also important in keeping water out of the DPIM. It is critical that all screws are properly
torqued to the values listed in Tech Data. Table 2 contains references for part numbers and torques; refer to the
Parts Catalog PC3717 and Service Manual SM3602 Appendix E for more information. Screws that are broken or
missing must be replaced to prevent water intrusion into the DPIM. Bosch thread repair kit J­51101 (detailed in SIL
21­EP­13) contains tools for repairing AC and DC lug box cover threads.
Table 2. Screw Torque Table
Screw Description

P/N

Torque

Quantity

DPIM Main Cover (M5 x 18mm)

29540732

3.1­3.5 N m (27­31 in­lb)

26

AC & DC Lug Box Cover (M4 x 12mm)

29540533

1.2­1.5 N m (10.6­13.3 in­lb)

28

High Voltage Cable Flange (M6 x 20mm)

n/a

5.3­6.0 N m (47­53 in­lb)

12
12

Signal Interface & Encoders (M4 x 14mm)
DC Lug Box to Housing (M4 x 14mm)

29540721

1.2­1.5 N m (10.6­13.3 in­lb)

AC Choke to Housing (M4 x 14mm)

12
20

Finally, it is important to ensure water does not enter the DPIM through the high voltage and low voltage
connectors. The low voltage connectors provided by the OEM should be inspected for missing, worn, or damaged
seals. Cavity plugs are to be installed in unpopulated pin locations in the low voltage harness to keep water from
entering the DPIM. The single­use gaskets on the cable flanges and proper assembly of the flange assembly will
keep water from entering the DPIM. Table 3 shows part numbers for these seals, plugs, and gasket. Figure 3 shows
some of these parts. Refer to the Troubleshooting Manual TS5812 or TS3715 Appendix E for more information.

Copyright © 2016 Allison Transmission, Inc. All Rights Reserved.

SIL 19­EP­16
April, 2016
Page 4 of 6
Table 3. Part Suppliers and Numbers
Description

Supplier

P/N

Quantity

High Voltage Cable Flange Gasket

Allison Transmission

29550771

3

Seal, 24­way

Delphi

12110403

1

Seal, 32­way

Delphi

15305333

2

Cavity Plug, 100W

Delphi

12129557

45

Service Parts:
It is important to remember that a DPIM2 is serviceable while a DPIM1 is not serviceable. Table 4 shows service
kits and the related SIL with parts ordering information and procedures. Refer to the Service Information Letters
link on the Allison Extranet for more information and the latest SILs.
Table 4. SIL List
Description

SIL

HVIL Card

03­EP­14

Passive Discharge Resistor

04­EP­15

BCA Card

02­EP­16

Current Sensors

12­EP­14

SKiM® Modules

01­EP­15

Table 5 provides a reference to recently released DPIM2 parts available for service. Refer to Parts Catalog
PC3717 for more information and a complete parts list.
Table 5. DPIM2 Parts Available
P/N

Description

P/N

Description

29540559

Cover, White, DC Capacitor

29546803

Harness, Signal Interface to BCA

29540604

Terminal Block, DC

29546806

Terminal Block, AC

29540711

Signal Interface Gasket

29546996

Choke, AC

29540736

Caution Label, HV Cover

29547434

Encoder Card, Inverter B

29546732

Busbar, DC Link

29547435

Signal Interface Card

29546737

Choke, DC

29546461

Encoder Card, Inverter A

29546764

AC Busbar, Inverter B

29549263

Shelf, BCA, Inverter B

29546765

AC Busbar, Inverter A

29549264

Shelf, BCA, Inverter A

29546766

Harness, Inverter A, HVIL to BCA

29549340

HVIL Support

29546767

Harness, Inverter B, Encoder to BCA

29549656

Diode, Signal Interface, Indicator

29546768

Harness, Inverter B, HVIL to BCA

29549915

Busbar, AC Link

29546769

Harness, Inverter A, Encoder to BCA

Copyright © 2016 Allison Transmission, Inc. All Rights Reserved.

SIL 19­EP­16
April, 2016
Page 5 of 6

Figure 1. Various DPIM Gaskets

Figure 2. Improper Gasket Installations

Copyright © 2016 Allison Transmission, Inc. All Rights Reserved.

SIL 19­EP­16
April, 2016
Page 6 of 6

Figure 3. High Voltage and Low Voltage Gaskets and Plugs

Copyright © 2016 Allison Transmission, Inc. All Rights Reserved.

DC
Terminal
Block

DC Lug
Box

AC Lug Box
Inverter B

AC Lug Box
Inverter A

AC Terminal
Block (x2)

AC Busbar (x6)

Diode
Inverter B

Diode
Inverter A

DC Busbar

Level 3

Current
Sensor (x6)

Level 1

BCA Card
Inverter B

BCA Card
Inverter A

X-Capacitor
(x18)

HVIL
Circuit
Board

HVIL
Switch

NOTE: This illustration is to be used for identifying the name and location
of components within the Dual Power Inverter Module 2 (DPIM2). It is not
intended to be used for disassembly and assembly procedures.

HVIL
Switches

Copyright 2014 Allison Transmission, Inc. All Rights Reserved.

Levels of Assembly

DPIM2

C

A

B

B

Level 2

Gate Drive
Cards
Inverter B

Phase

Phase

Gate Drive
Cards
Inverter A

Level 4

DC Capacitor SKiM Module/IGBT
(x9)
Cards Inverter B

SKiM Module/IGBT
Cards Inverter A

Encoder
Motor B

Phase

Phase

HVIL Support

Discharge
Resistor

DC Choke

Encoder
Motor A

A

C

AC Bus Bar
Inverter B

Phase

Phase

AC Bus Bar
Inverter A

GN7499EN
201405

Signal
Interface