HYBRID BASIC COMPONENT INTRODUCTION, SAFETY TSB #: 67 PRECAUTIONS AND HAZARDS - PART 1 Date: 10/10/2012 Initial Once Read: A Hybrid vehicle uses a power train that is both a small capacity combustion engine and an electric motor. The combustion engine could be petrol, diesel or even LPG powered and is used to drive the wheels and under certain conditions assist the electric motor to charge the batteries and also drive the wheels. There are 3 types or designs of Hybrid systems that operate differently from each other: Access fitting SERIES The engine is used to operate the generator that charges the main battery pack or the engine powers the electric motor. The engine does not directly drive the wheels. PARALLEL The engine drives wheels via the power splitter and transmission. The electric motor is also connected to the power splitter and drives the wheels along with the engine. The electric motor can also be used as a generator to charge the battery pack when it is not driving the wheels.
SERIES PARALLEL The engine drives the wheels via the power splitter and transmission and the generator that recharges the battery pack. The battery pack powers the electric motor which drives the wheels via the power splitter. A computer controls each system as or when required. The generator can charge the battery pack while the car is running. A B Powers C Charges Drives E D F Drives Example of the Parallel Design Hybrid System: A: Battery Pack B: Electric Motor C: Generator D: Transmission / Power Splitter E: Petrol Engine F: Drive Wheels & Regenerative Braking
COMPONENTS THAT MAKE UP A HYBRID SYSTEM: Internal Combustion Engine - The main difference between the hybrid engine and a standard vehicle engine is a difference to the cam timing and an economical smaller displacement engine size. Electric Motor - A 3-Phase electric motor is used to operate the drive wheels and can also be used as a generator on some vehicles to charge the high voltage battery pack. Regenerative braking - When the foot brake is applied, the electric motor operates in reverse, converting the vehicle kinetic energy into electrical energy to charge the battery pack. Inverter / Convertor - Converts and increases DC voltage from the battery packs at approximately 200 volts to AC voltage at a maximum 650 volts to drive the (3-Phase) electric motor and to use in the generator. The inverter can also reduce the 200 volts battery pack voltage down to 12 volts to charge the auxiliary battery. Transmission Incorporates the reduction gear, splitter device and the reduction gears. The transmission is continuously variable that can change speed by varying the engine, generator and electric motor rpm. Battery Pack - Is made up of a large number of low voltage batteries connected in series. The voltage output is around 200 volts. There are 2 types of battery pack; Nickel Metal Hydride (NiMH) and Lithium-ion (Li-ion). Both these types of batteries are influenced by heat. Sensors placed in and around the battery pack are connected to a dedicated computer which signals the battery cooling fans to operate and reduce battery temperature. A/C cold air may also be used to cool the batteries on some vehicles. Electronics Battery Pack Cooling Fan Auxiliary Battery - Lead acid design and kept charged by the inverter. This battery is used to supply voltage to the standard low voltage electrical system such as lights, wipers and accessories. Located in the boot or engine bay of the vehicle. Generator - Used in the Series and Series-Parallel system designs. The function of the generator is to charge both the high 201 volts battery pack and the 12 volt auxiliary battery. Power Splitter Device - Essentially it is a planetary drive which is used to distribute power evenly between the engine and the electric motor to the drive wheels. Insulated Wiring Colours - The colour of the wiring insulation indicates the level of electrical hazard and voltage contained within that wiring. Refer to the safety section of this TSB. Shut Down Safety Switch - The safety switch is used to isolate the high voltage systems and battery pack for vehicle servicing, repair or diagnosis. Some components also use capacitors, these have to power down over a certain time frame. A/C Compressor - All-in-one electric drive motor and compressor. The compressor electric motor operates on high AC voltage provided from the inverter. An orange coloured electrical harness is used to indicate high voltage.
Electric motor, Generator & Starter Motor Constantly Variable Transmission (CVT) & Splitter Petrol Engine HIGH VOLTAGE: HIGH VOLTAGE CAN KILL! The voltages produced in a hybrid vehicle are between 200-600 volts. The battery pack DC voltage is more dangerous than AC voltage created by the inverter. 50 volts DC is more dangerous than 240 volts AC. The higher the voltage and current flow, the more severe damage can occur to the human body. At high voltage and current flow of 30mA you could stop breathing and at 75-100 your heart could stop pumping and lead to death. Extreme caution MUST be applied when working on Hybrid vehicles. SAFETY PRECAUTIONS: Whenever you see orange coloured electrical cables this indicates that high voltage is present. Insulated gloves and other PPE MUST BE USED and the battery pack isolated. Electric AC Compressor With the electric AC compressor, specific non-conductive lubrication oil MUST be used designated as Denso - ND-11, Honda SE-10Y
SAFETY PRECAUTIONS CONTINUED: When using coloured wiring diagrams to trace a circuit note the wire colours. Black = 12-14 Volts Blue = 30-50 Volts Orange = 200-600 Volts (extreme danger HIGH voltage) Some Hybrid vehicles use proximity keys meaning that all you have to do is hold the key pad close to the dash to turn the ignition on. The key pad must be placed in a position 5 meters away from the vehicle to disrupt the remote signal. Do not put the key pad in your pocket. If the vehicle uses a key remove it from the ignition. Before commencing any work on the vehicle check the instrument cluster ready lamp to ensure that it is off. If the ready lamp is illuminated this indicates that the vehicle is ready to operate. When working on the high voltage side of the Hybrid vehicle, ALWAYS WEAR THE FOLLOWING PPE: Linesmans insulated gloves class 0 rated to 1000 volts also leather gloves which are used to protect the insulated gloves. Eye protection. Rubber soled shoes. No loose tools in work wear pockets that could fall onto electrical components or terminals
SAFETY PRECAUTIONS CONTINUED: Disconnect the Auxiliary 12 volt battery as this does feed into the main battery pack circuit. Disconnect the negative battery terminal. After turning off the battery pack safety switch or device, allow 15-20 minutes for the capacitors in the system to discharge. These capacitors can keep the battery circuit active. Capacitors Locate the battery pack isolation / safety switch or device. Vehicle manufacturers have different types of isolation devices and they are located in various areas, most commonly in the boot. Consult the owners handbook, contact the vehicle manufacturer customer service or visit the manufacturer s website. Below is an example of the various isolation switches and locations. DO NOT WORK ON A HYBRID VEHICLE ELECTRICAL SYSTEM UNTILTHE BATTERY PACK ISOLATION PROCEDURE HAS BEEN CARRIED OUT. Toyota Prius 2nd Generation Honda Civic Acknowledgement Some of the information and pictures contained in this TSB have been taken from training notes and technical information from the IAME, Toyota, Honda and the NSW Fire Brigade (emergency procedures). Always consult the vehicle workshop manual for full safety instructions. This TSB was created in the interest of technician knowledge and personal safety.