NissanTechNewsSummer2012:MarchStarTuned2005 9/14/12 5:22 PM Page 4 Nissan & Infiniti Tech News Feature | New Growth: The Nissan LEAF 4 | Nissan & Infiniti Tech News NissanTechNewsSummer2012:MarchStarTuned2005 9/14/12 5:22 PM Page 5 ® The LEAF was introduced in 2011 as Nissan’s pio- Nissan’s all-electric neer vehicle for the future of electric cars. It has a dis- tinctive body design not based on any other platform in LEAF incorporates the Nissan fleet, giving it a road presence unlike any other compact car. Prominent LED headlights and a long LED cluster tail light, coupled with blue-chrome both new and existing accents make the LEAF impossible to confuse with other vehicles. plus, once you pop the hood, nearly the technologies. only thing that looks normal is the faux “valve cover.” Let’s take a closer look at the features of the new This article will LEAF to try to strip away some of the mystery. familiarize readers with the unique features and design of this car, and provide insight into its expected maintenance and service needs The stylish faux valve cover is set on top of the inverter unit and creates a traditional engine in the future. bay appearance. Nissan & Infiniti Tech News | 5 NissanTechNewsSummer2012:MarchStarTuned2005 9/14/12 5:22 PM Page 6 Nissan & Infiniti The NIssan LEAF Overview The traction motor takes the place of a conventional The LEAF is a front wheel-drive car, utilizing an all- engine, and generates torque from precisely-controlled electric three-phase traction motor and reduction gear electromagnetic fields. The motor is basically two pri- to drive the CV axles. The motor gets its power from a mary components: the permanent magnet rotor, and the lithium-ion battery pack composed of 48 modules in coil windings of the stator. Information about tempera- series, each containing four ture or speed sensor loca- laminated cells to produce a tions, cooling tubes, and total of 403V. A water- high-voltage connections, cooled inverter changes bat- or other specific compo- tery power as necessary nents can be found in the from DC to AC to drive the service manual. motor, and, likewise, from When three-phase AC motor-generated AC (from current is applied to the regenerative braking) to DC stator coil windings, a con- to charge the battery pack. trolled electromagnetic Regenerative battery charg- field is generated. This ing is achieved by converting field pulls on the perma- the kinetic energy of the nent magnet inside the already moving car into rotor, causing the rotor to power through induction chase the generated field. within the traction motor. The Vehicle Control The suspension is independ- Module (VCM) can create ent MacPherson struts in the a constantly rotating elec- front, and a solid I-beam in tromagnetic field using a the rear with shocks. rotor position (angle) sen- Steering input is rack and sor, much as an internal pinion, with an electronically- The traction motor consists of the combustion engine regu- controlled electric power stator core (1), coil windings (2), output lates ignition and fuel steering rack. It’s equipped shaft (3), rotor core (4) and permanent using crank and cam sen- with standard ABS using magnet (5). sors. The torque generat- four-wheel disc brakes. ed by the electric motor is Vehicle Dynamic Control approximately proportion- (VDC) is standard, and enhances safety and handling. al to the amperage of the current, whose frequency (or The instrument panel has two separate displays for pulse timing) affects the rotational velocity. Current the driver, showcasing unique LED styling for electric application is controlled by the VCM monitoring posi- power consumption, and Nissan’s usual dot-matrix infor- tion with the traction motor resolver and current flow mation screen. An integrated navigation unit comes from a sensor within the inverter. standard, using GPS and telematics to show the vehi- Some DTCs (Diagnostic Trouble Codes) will limit the cle’s estimated range and nearby quick charge locations. rotor rotational speed, the torque output of the motor, or both as a precaution. A P3240 “Drive Motor Current Powertrain Control Malfunction” may set if the VCM does not see expected changes in current application due to sensor The first description of the LEAF is invariably that it’s error or an internal problem. The LEAF requires a CON- “an electric car,” so we should begin with how it works SULT-III plus for diagnosis and repair. without an internal combustion engine. Like an internal combustion engine that performs 6 | Nissan & Infiniti Tech News NissanTechNewsSummer2012:MarchStarTuned2005 9/14/12 5:22 PM Page 7 differently according to changes in the intake charge modes, when the battery is at the fully charged state, and timing, an electric motor is dependent upon the fre- no regeneration is performed. This is to protect the quency and amperage of the supplied current. It is the battery from overcharging. job of the VCM and the inverter to create the equivalent The heart of the powertrain is the 403V Li-Ion battery of an intake charge for the traction motor. It does this pack, arranged beneath the floor of the leaf. Every cell of by adjusting voltage based the 48 modules is moni- on two calculated values: tored, and the CONSULT-III target force, and motor plus can display many rele- torque request signal. vant PIDs for the battery Because the resistance pack, such as module volt- within the system is con- ages, total voltages, charg- stant, changes in voltage ing/discharging voltage dif- affect amperage propor- ferences, and the four bat- tionally – think Ohm’s Law. tery temperature sensor Target force is based signals. Yes, if there is a upon sensor input from the battery cell malfunction, a accelerator pedal position, DTC will point directly at the vehicle speed, and shift problem cell. Considering position. Other systems like the pack weighs a total 648 ABS or VDC will send lbs., we should be thankful torque-down signals to the that any one of the modules VCM to reduce motor can be replaced in the torque output. Once deter- event of failure. mined, the VCM will com- The LEAF comes stan- mand the inverter to con- dard with two ways of vert DC from the battery charging the battery pack pack into AC of the specif- at home using domestic ic amperage (torque) and AC. The “Normal Charge” frequency (rotational This diagram indicates the location of the method requires profes- speed). Thanks to thermo- 403V lithium-ion battery pack (1) and the sional installation of a dynamics, this conversion service plug (2). 240V source at home, and work also generates heat achieving a full charge will which is transferred into take approximately six the cooling system and dissipated by the radiator in a hours. The “Trickle Charge” method will allow 120V traditional manner. household electricity to fully charge the battery in The LEAF also charges the battery by working in approximately 21 hours. The trickle charge method is the reverse of the above method. Instead of creating not recommended for normal use according to the synchronous electromagnetic fields, during regenera- Owner’s Manual, but can be useful when at a friend’s tion the outer field is maintained stationary. The rotor house. This charging method may use power a bit magnet moves through the field creating a current erratically, charging and discharging capacitors for flow by the electrical property of induction. This AC example, that may trip household breakers or cause current is captured by the inverter, converted to DC, other leaks to ground. Anecdotally, it appears that the and stored in the battery pack. The VCM performs the trickle charge is not recommended due to its unrelia- regenerative charge constantly at deceleration, effec- bility. Using the trickle charge method will not cause tively slowing the vehicle. In ECO mode, the LEAF will damage to the vehicle. It is best to follow Nissan’s rec- regenerate more aggressively; however, in both ommendation. Nissan & Infiniti Tech News | 7 NissanTechNewsSummer2012:MarchStarTuned2005 9/14/12 5:22 PM Page 8 Nissan & Infiniti The NIssan LEAF The port on the left is for quick charge. Shown here, the LEAF is using the shop’s 240V to get a little charge while in for service. An optional “Quick Charge” port can be installed in the Transmission and Drivetrain LEAF, allowing a zero to 80% State of Charge (SOC) in about 30 minutes. These high-powered stations are The LEAF does not have a CVT or planetary gear available in some locations, and can be found using the transmission, but rather a reduction gear that looks much LEAF’s navigational unit. However, repeated Quick like the gears in a shop roll-up gate. The electric motor Charging may shorten the lifespan of the battery pack. output speed and torque can be precisely controlled so Every 12 months, regardless of mileage, Nissan there is no need for a conventional transmission’s chang- requires the annual Battery Usage Report for warranty ing gear ratios. On top of the reduction gear housing is purposes. This must be done with the CONSULT-III where the electronic park position actuator lives, and a plus. We will discuss the report below in the mainte- parking pawl is found inside the case. The LEAF uses a nance section. unique parking feature, which can be set or released with 8 | Nissan & Infiniti Tech News NissanTechNewsSummer2012:MarchStarTuned2005 9/14/12 5:22 PM Page 9 the electric shift selector, which power of the regeneration inputs the command (park, drive or process by monitoring the AC reverse) to the shift control module.. generated – simply the inverse Once set, the BCM transmits the of how it calculates target motor ON/OFF command to the electron- speed and torque.