by Russell Krick Publisher The GoodheartWillcox Co Inc
by Russell Krick Publisher The Goodheart-Willcox Co. , Inc. Tinley Park, Illinois © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
© Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
q q q Introduction to Hybrids Hybrid System Voltages Hybrid Drive Assemblies Hybrid Service Safety Hybrid Problem Diagnosis Hybrid Battery Pack Service (Continued) © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
q q q 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 © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
q Hybrid vehicles (HVs) use two individual power sources to provide energy for propulsion minternal combustion engine melectric drive system © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
q Hybrid gas-electric vehicles (HGEVs) are currently produced q Others are in development: mfuel cell hybrid mhydraulic hybrid mpneumatic hybrid © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
q Hybrids can be identified in two ways m. Badging on the front fender, engine cover, or hood m. The 5 th, 6 th, and 7 th alphanumeric characters in the VIN © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Hybrid Vehicle History q In 1898, Ferdinand Porsche built a gaselectric hybrid msmall internal combustion engine to spin a large generator mdrive motors at each wheel msame concept is used in modern locomotives © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Hybrid Drive Vehicle q In a gas-electric hybrid, the engine and electric drive system work together q There are six major components: m high-voltage battery pack m motor-generator m power control module m hybrid drive ECU m power cables m internal combustion engine © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Hybrid Types q Full hybrid muses a motor-generator for propulsion muses an internal combustion engine to drive the generator to recharge the battery pack © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Hybrid Types q Mild hybrid mpropelled by an internal combustion engine mengine shuts off during braking, coasting, and stops mhigh-powered starter-alternator restarts the engine when brakes are released melectric motors drive accessory items so they are available when the engine is off © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Hybrid Drive Train Configurations q Series hybrid q Parallel hybrid q Series/parallel hybrid © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Series Hybrid q Separate generator and traction motor(s) q Engine drives the generator; separate traction motors propel the vehicle q No mechanical connection between the engine and drive train © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Series Hybrid © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Parallel Hybrid q Engine and motor-generator can both propel the vehicle q Functions as a standard gasoline-powered vehicle for hard acceleration and high-speed operation q Functions as an all-electric vehicle for city driving q Motor-generator can switch between charging and propulsion, but cannot do both simultaneously © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Parallel Hybrid © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Series/Parallel Hybrid q Separate generator and traction motor(s) q Combines the advantages of parallel and series hybrids q Engine can propel the vehicle and drive the generator to change the battery pack at same time q Power splitter is used to transfer engine and electric motor power through the drive train © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Series/Parallel Hybrid © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Hybrid Vehicle Operation q Five modes of operation mall-electric drive mmotor assist midle stop mregenerative braking mengine starting © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
All-Electric Drive Mode q Battery pack provides all energy needed to propel the vehicle q Many hybrids stay in all-electric mode when accelerating up to 20 -40 mph q When a hybrid runs on electrical energy only, it burns no fuel and emits no hydrocarbons © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
All-Electric Mode The engine is off, and the motorgenerator propels the vehicle © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Motor Assist Mode q Both the motor-generator and internal combustion engine apply torque to the drive train for propulsion © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Motor Assist Mode The engine and motor-generator work together to propel the vehicle © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Idle Stop Mode q Internal combustion engine is shut off when the vehicle comes to a stop q The engine restarts when the vehicle reaches a predetermined speed or when the battery pack is discharged © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Regenerative Braking Mode q When brakes are applied, the motorgenerator functions as a generator q The drag created by the generator slows the vehicle and recaptures the vehicle’s kinetic energy q Hydraulic brakes are applied only for hard braking © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Regenerative Braking Mode Motor-generator slows the vehicle while generating electricity © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Engine Starting Mode q Hybrid ECU: menergizes transmission solenoids to lock the motor-generator and engine together msends just enough current to the motorgenerator to turn the engine at about 300 rpm msignals the engine ECU to provide spark and fuel to the engine © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Battery Pack Charging Mode q When the hybrid ECU detects low battery pack charge, it restarts the engine to propel the vehicle and recharge the battery pack © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Battery Recharging Mode Engine drives the motor-generator to recharge the battery pack © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
q Hybrids use two voltage systems, wired separately but interfaced through the ECU and power control module mhigh-voltage system mlow-voltage system © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
High-Voltage System q Operates on voltages ranging from 250– 650 volts ac or dc m hybrid drive and charging circuits q Hybrid nominal output voltage m maximum dc voltage available from battery pack m typically 100 to more than 300 volts q Hybrid maximum voltage m the 3 -phase ac voltage fed to the motorgenerator from the power control module m up to 650 volts ac © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Low-Voltage System q Uses conventional 12 -volt battery q Maintains computer memory q Provides low voltage to electrical accessories and low-voltage electrical engine components mfuel injectors mignition coil msensors © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
q Battery pack q Motor-generator q Power control module q Hybrid drive ECU q Power splitter © Goodheart-Willcox Co. , Inc. q Hybrid power cables q Numerous switches, relays, fuses, connectors, and sensors q Cooling system Permission granted to reproduce for educational use only
Battery Pack q Several high-efficiency nickel metal hydride (Ni. MH) battery modules m Stacked in a sealed enclosure m Wired in series for high voltage © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Battery Pack q Designed to handle very high current flow rates during battery discharge q Very good weigh-to-power ratio q Voltage can range from 150 -300 volts dc q Sensors monitor cell temperature q If a battery problem exists, the hybrid ECU will light a warning light on the dash and shut down the electric drive system © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Motor-Generator q Functions as both a powerful traction motor and a high-energy alternator m helps propel the vehicle m recharges the HV battery pack m cranks the internal combustion engine m helps slow and stop the vehicle q Construction is similar to other motors and alternators m consists of armature, stator, and housing m armature spins in close proximity to the stator © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Motor-Generator Construction The typical motor-generator uses permanent magnets in the armature and electromagnets in the stator © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Motor-Generator as a Motor q Permanent magnet design improves reliability q 3 -phase ac current energizes stator m sets up a 3 -wave magnetic field that moves around the stator, pushing and pulling the armature with it m more horsepower and torque and better efficiency than equivalent dc motor m torque is controlled by current flow m speed is controlled by frequency and phase shift of ac waves © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Motor-Generator as a Generator q Functions as a generator when the battery becomes discharged and during regenerative braking q Internal combustion engine or drive train spins the motor generator’s permanent magnet armature m armature’s magnetic fields pass through stator windings m induces ac current in the stator windings © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Single Motor. Generator Hybrid The least complex hybrid drive configurations use a single motor-generator © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Dual Motor-Generator Hybrid The dual motor-generator configuration is capable of simultaneously propelling the vehicle and recharging the battery pack © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Triple Motor-Generator Hybrid Triple motor-generator arrangements are used in all-wheel and four-wheel drive hybrids © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Power Control Module q Alters current and routes it between the HV battery pack and motor-generator q Converter circuit steps dc voltage up or down q Inverter circuit changes dc to 3 -phase ac or 3 -phase ac to dc q Motor-generator ECU controls the converter and inverter circuits to efficiently operate the motor-generator(s) © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
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 © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Battery Relays and Contactors q Control the flow of electricity between the battery pack and the power control module q When the ignition key is off mbattery relays and contactors are open mno current can flow to the power control module and motor-generator © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Battery Relays and Contactors q When the ignition key is turned to run mbattery relays close and energize contactor coils mcontactor closes mcircuit is completed between battery pack and power control module © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Hybrid Drive ECU q Controls the power control module and motor-generator mkeeps the HV battery pack operating at optimum temperature and state of charge q Receives input from pedal position and other sensors muses sensor input data to determine the properating mode for the motorgenerator © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Power Splitter q Planetary gearset used to transfer power through the hybrid drive train msolenoids apply and release friction members to control the planetary gearset mcan control flow of torque from both the internal combustion engine and the motor -generator(s) q Power splitter and drivetrain are under computer control © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Hybrid Power Cables q Heavily insulated cables transfer extremely high voltages q Two cables connect power control module to the battery pack q Three cables connect the power control module to the motor-generator morange insulation for easy identification © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
High-Voltage Circuit Protection q Ground fault interrupter mconstantly monitors the system for highvoltage leakage into the chassis milluminates a warning light and opens power relays if high voltage from the battery pack or motor-generator shorts to ground q High-voltage fuse mpermanently burns open if current in the circuit is too high © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Sensors q Impact sensors mopen the high-voltage circuits, disable the fuel pump, and deploy airbags in a severe impact q Motor-generator sensor mdetects the speed and position of the motor-generator armature © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Hybrid Drive Cooling q Water cooling mcirculates engine coolant through the transaxle, motor generator(s), and power control module mcarries heat to the radiator mmany hybrids have two radiators: one conventional and one for the hybrid drive system © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Hybrid Drive Cooling q Air cooling muses an electric blower to circulate air through the battery pack enclosure q Refrigerant cooling mcirculates R-134 a refrigerant through an evaporator next to the battery pack or PCM © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Hybrid Dash Display Combination meter comprises numerous individual gauges and displays hybrid drive operating conditions © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Hybrid Dash Display q Hybrid power display informs the driver about how electrical energy is being used and how much charge remains in the battery pack q Hybrid drive ready light glows continuously when the vehicle is ready to be driven q Hybrid master warning light indicates problems in the drivetrain q Battery pack warning light indicates low charge in the battery pack © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
q Hybrids generate and store enough electrical energy to cause electrocution q Safe work habits are extremely important when working on hybrids © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Hybrid Safety Precautions q Remove all jewelry before working on a hybrid’s high-voltage circuits mhigh voltage can arc through air and into jewelry q Wear insulating gloves muse OSHA-approved lineman’s gloves rated at 1000 volts or better mbefore working, check gloves for leaks © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Hybrid Safety Precautions q Wear rubber-soled shoes q Keep a fire extinguisher nearby mmake sure extinguisher is suitable for electrical fires (class C) q When towing, raise any wheels connected to drive motors q Turn the ignition key off and disconnect the 12 v battery to disable drive before working © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Hybrid Safety Precautions q Move metal equipment out of the work area to avoid accidental electrocution q Use the high-voltage disconnect to physically disconnect the battery pack from the power control module mwait at least five minutes after disconnection to begin work © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
q Onboard diagnostics monitor hundreds of operating conditions and turn on a warning light if a problem is detected q Use a scan tool to retrieve codes if a malfunction indicator light is glowing q Hybrid drive troubles are assigned specific codes © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
q Hybrid battery packs have a warranty from the vehicle manufacturer q Battery packs are very dependable, though electrolyte and plates can be depleted after many years of operation q Ni. MH batteries should not be stored for long periods © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Battery Pack Recharging q Hybrid battery charger uses a step-up transformer to force high-voltage into the battery pack mbattery packs that fail to take a full charge should be replaced © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Battery Pack Recharging q If the vehicle has a conventional 12 -volt battery, it can usually be jump-started with booster cables mnever try to jump-start an HV battery pack with a 12 -volt booster battery, or the battery will explode © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Battery Pack Testing q To check battery pack performance, connect a scan tool and test-drive the vehicle muse regenerative braking and drive uphill to place demands on the system mthe combination meter and scan tool will indicate the battery pack’s state of charge, battery voltage, and recharge current © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Battery Pack Testing mcompare results to known good battery pack or manufacturer’s specifications mif the battery pack does not hold charge, produces insufficient current, or has poor capacity, it should be replaced © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Battery Pack Testing q If high battery temperatures are indicated, use an infrared thermometer to compare cell temperatures m if only one cell runs warm, it is probably shorted and the battery pack should be replaced m if all cells are warm, check cooling system q Check for problems in an air cooling system m blower electrical or mechanical problems m damaged or blocked air intake ducts © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Battery Pack Replacement q Battery packs are usually located in the trunk or under the rear seat cushion or floor pan q Most common reason for replacement is damage from a collision q Be careful removing a battery pack m wear insulated rubber gloves and eye protection m use an assistant or an engine hoist to lift the battery pack m place high-voltage warning labels on the shipping container © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
q Check should be done if trouble codes indicate that the battery is OK, but power is not reaching the power control module q Contactor lugs can become burned and pitted © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
q If burned, contactor lugs will develop increased resistance and may not deliver sufficient current to the PCM q When measuring high voltage, use only high-voltage meter with leads having thick insulation © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
q Check resistance values of cables in the scan tool’s data list display mif resistance is too high, tighten or repair cable ends, or replace cables if needed q If the scan tool reading indicates a ground fault, perform an ohmmeter test between cable connector and ground mif resistance is too low (<350 k ohms), the cable may be shorting to ground © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
q A loose cable end can overheat and burn the electrical connection q Always torque cable fasteners to factory specs © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
Checking Cable for Voltage Leak If resistance between the cable connector and ground is too low, voltage may be leaking © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
q Common problems mcircuit board failure mfaults caused by overheating q Some hybrids use a separate power converter mif scan tool indicates an internal converter problem, the converter should be removed and replaced © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
q If the system is air cooled, listen for normal cooling fan operation mif the blower motor is bad, replace it the way you would a climate control blower mdisconnect ducts and wiring before removing the fasteners securing the blower © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
q If the system is liquid cooled, use a stethoscope to listen to pump operation mensure the pump operates during high electrical load conditions © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
q Coil windings can short or burn open mscan tool will show code mcombination gauge will indicate poor performance during all-electric mode and regenerative braking © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
q Follow manufacturer’s procedures for replacing the motor-generator or its components ma plastic sleeve may be inserted between the stator and armature to prevent contact mmake sure the work area is clean and free of iron filings and other debris © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
q If scan tool indicates a problem in a particular component but the component tests good, check the wiring muse factory wiring diagrams mlocate and check connectors and other components that could be affecting the circuit © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only
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