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

Publisher The Goodheart-Willcox Co., Inc. Tinley Park, Illinois. PowerPoint for. Modern Automotive Technology. by Russell Krick. Chapter 38. Hybrid Drive System Operation and Repair. Contents. Introduction to Hybrids Hybrid System Voltages Hybrid Drive Assemblies Hybrid Service Safety

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

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  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

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