Publisher The Goodheart-Willcox Co., Inc. Tinley Park, Illinois

1. PublisherThe Goodheart-Willcox Co., Inc.Tinley Park, Illinois PowerPoint for Modern Automotive Technology by Russell Krick

2. Chapter 38 Hybrid Drive System Operation and Repair

3. Contents • Introduction to Hybrids • Hybrid System Voltages • Hybrid Drive Assemblies • Hybrid Service Safety • Hybrid Problem Diagnosis • Hybrid Battery Pack Service (Continued)

4. Contents • Checking HV Battery Relays and Contactors • Servicing Hybrid Power Cables • Servicing the Power Control Module • Servicing the Hybrid Cooling System • Servicing the Motor-Generator • Hybrid Wiring Problems

5. Introduction to Hybrids • Hybrid vehicles (HVs) use two individual power sources to provide energy for propulsion • internal combustion engine • electric drive system

6. Introduction to Hybrids • Hybrid gas-electric vehicles (HGEVs) are currently produced • Others are in development: • fuel cell hybrid • hydraulic hybrid • pneumatic hybrid

7. Introduction to Hybrids • Hybrids can be identified in two ways • Badging on the front fender, engine cover, or hood • The 5th, 6th, and 7th alphanumeric characters in the VIN

8. Hybrid Vehicle History • In 1898, Ferdinand Porsche built a gas-electric hybrid • small internal combustion engine to spin a large generator • drive motors at each wheel • same concept is used in modern locomotives

9. Hybrid Drive Vehicle • In a gas-electric hybrid, the engine and electric drive system work together • There are six major components: • high-voltage battery pack • motor-generator • power control module • hybrid drive ECU • power cables • internal combustion engine

10. Hybrid Types • Full hybrid • uses a motor-generator for propulsion • uses an internal combustion engine to drive the generator to recharge the battery pack

11. Hybrid Types • Mild hybrid • propelled by an internal combustion engine • engine shuts off during braking, coasting, and stops • high-powered starter-alternator restarts the engine when brakes are released • electric motors drive accessory items so they are available when the engine is off

12. Hybrid Drive Train Configurations • Series hybrid • Parallel hybrid • Series/parallel hybrid

13. Series Hybrid • Separate generator and traction motor(s) • Engine drives the generator; separate traction motors propel the vehicle • No mechanical connection between the engine and drive train

14. Series Hybrid

15. Parallel Hybrid • Engine and motor-generator can both propel the vehicle • Functions as a standard gasoline-powered vehicle for hard acceleration and high-speed operation • Functions as an all-electric vehicle for city driving • Motor-generator can switch between charging and propulsion, but cannot do both simultaneously

16. Parallel Hybrid

17. Series/Parallel Hybrid • Separate generator and traction motor(s) • Combines the advantages of parallel and series hybrids • Engine can propel the vehicle and drive the generator to change the battery pack at same time • Power splitter is used to transfer engine and electric motor power through the drive train

18. Series/Parallel Hybrid

19. Hybrid Vehicle Operation • Five modes of operation • all-electric drive • motor assist • idle stop • regenerative braking • engine starting

20. All-Electric Drive Mode • Battery pack provides all energy needed to propel the vehicle • Many hybrids stay in all-electric mode when accelerating up to 20-40 mph • When a hybrid runs on electrical energy only, it burns no fuel and emits no hydrocarbons

21. All-Electric Mode The engine is off, and the motor-generator propels the vehicle

22. Motor Assist Mode • Both the motor-generator and internal combustion engine apply torque to the drive train for propulsion

23. Motor Assist Mode The engine and motor-generator work together to propel the vehicle

24. Idle Stop Mode • Internal combustion engine is shut off when the vehicle comes to a stop • The engine restarts when the vehicle reaches a predetermined speed or when the battery pack is discharged

25. Regenerative Braking Mode • When brakes are applied, the motor-generator functions as a generator • The drag created by the generator slows the vehicle and recaptures the vehicle’s kinetic energy • Hydraulic brakes are applied only for hard braking

26. Regenerative Braking Mode Motor-generator slows the vehicle while generating electricity

27. Engine Starting Mode • Hybrid ECU: • energizes transmission solenoids to lock the motor-generator and engine together • sends just enough current to the motor-generator to turn the engine at about 300 rpm • signals the engine ECU to provide spark and fuel to the engine

28. Battery Pack Charging Mode • When the hybrid ECU detects low battery pack charge, it restarts the engine to propel the vehicle and recharge the battery pack

29. Battery Recharging Mode Engine drives the motor-generator to recharge the battery pack

30. Hybrid System Voltages • Hybrids use two voltage systems, wired separately but interfaced through the ECU and power control module • high-voltage system • low-voltage system

31. High-Voltage System • Operates on voltages ranging from 250–650 volts ac or dc • hybrid drive and charging circuits • Hybrid nominal output voltage • maximum dc voltage available from battery pack • typically 100 to more than 300 volts • Hybrid maximum voltage • the 3-phase ac voltage fed to the motor-generator from the power control module • up to 650 volts ac

32. Low-Voltage System • Uses conventional 12-volt battery • Maintains computer memory • Provides low voltage to electrical accessories and low-voltage electrical engine components • fuel injectors • ignition coil • sensors

33. Battery pack Motor-generator Power control module Hybrid drive ECU Power splitter Hybrid power cables Numerous switches, relays, fuses, connectors, and sensors Cooling system Hybrid Drive Assemblies

34. Several high-efficiency nickel metal hydride (NiMH) battery modules Stacked in a sealed enclosure Wired in series for high voltage Battery Pack

35. Battery Pack • Designed to handle very high current flow rates during battery discharge • Very good weigh-to-power ratio • Voltage can range from 150-300 volts dc • Sensors monitor cell temperature • If a battery problem exists, the hybrid ECU will light a warning light on the dash and shut down the electric drive system

36. Motor-Generator • Functions as both a powerful traction motor and a high-energy alternator • helps propel the vehicle • recharges the HV battery pack • cranks the internal combustion engine • helps slow and stop the vehicle • Construction is similar to other motors and alternators • consists of armature, stator, and housing • armature spins in close proximity to the stator

37. Motor-Generator Construction The typical motor-generator uses permanent magnets in the armature and electromagnets in the stator

38. Motor-Generator as a Motor • Permanent magnet design improves reliability • 3-phase ac current energizes stator • sets up a 3-wave magnetic field that moves around the stator, pushing and pulling the armature with it • more horsepower and torque and better efficiency than equivalent dc motor • torque is controlled by current flow • speed is controlled by frequency and phase shift of ac waves

39. Motor-Generator as a Generator • Functions as a generator when the battery becomes discharged and during regenerative braking • Internal combustion engine or drive train spins the motor generator’s permanent magnet armature • armature’s magnetic fields pass through stator windings • induces ac current in the stator windings

40. The least complex hybrid drive configurations use a single motor-generator Single Motor-Generator Hybrid

41. Dual Motor-Generator Hybrid The dual motor-generator configuration is capable of simultaneously propelling the vehicle and recharging the battery pack

42. Triple Motor-Generator Hybrid Triple motor-generator arrangements are used in all-wheel and four-wheel drive hybrids

43. Power Control Module • Alters current and routes it between the HV battery pack and motor-generator • Converter circuit steps dc voltage up or down • Inverter circuit changes dc to 3-phase ac or 3-phase ac to dc • Motor-generator ECU controls the converter and inverter circuits to efficiently operate the motor-generator(s)

44. Power Control Module Two wires run from the power control module to the battery pack; three wires run from the power control unit to the motor-generator

45. Battery Relays and Contactors • Control the flow of electricity between the battery pack and the power control module • When the ignition key is off • battery relays and contactors are open • no current can flow to the power control module and motor-generator

46. Battery Relays and Contactors • When the ignition key is turned to run • battery relays close and energize contactor coils • contactor closes • circuit is completed between battery pack and power control module

47. Hybrid Drive ECU • Controls the power control module and motor-generator • keeps the HV battery pack operating at optimum temperature and state of charge • Receives input from pedal position and other sensors • uses sensor input data to determine the proper operating mode for the motor-generator

48. Power Splitter • Planetary gearset used to transfer power through the hybrid drive train • solenoids apply and release friction members to control the planetary gearset • can control flow of torque from both the internal combustion engine and the motor-generator(s) • Power splitter and drivetrain are under computer control

49. Hybrid Power Cables • Heavily insulated cables transfer extremely high voltages • Two cables connect power control module to the battery pack • Three cables connect the power control module to the motor-generator • orange insulation for easy identification

50. High-Voltage Circuit Protection • Ground fault interrupter • constantly monitors the system for high-voltage leakage into the chassis • illuminates a warning light and opens power relays if high voltage from the battery pack or motor-generator shorts to ground • High-voltage fuse • permanently burns open if current in the circuit is too high