Week-6 Challenge: EV Drivetrain
1.ELECTRIC VEHICLES:
An electric vehicle is a vehicle that uses one or more electric motor or traction motor for propulsion an electric vehicle may be power through a collector system by electricity from off vehicle source may be self contained with a battery solar panels fuel cell electric generator to convert fuel to electricity
HYBRID ELECTRIC VEHICLE:
A hybrid electric vehicle is a type of hybrid vehicles that combines a conventional internal combustion engine system with an electric propulsion system the presence of the electric powertrain is intended to achieve either better fuel economy than a conventional vehicle or batter performance. there is a variety of HEV type and the degree to which each function as electric from of HEV is the hybrid electric car although hybrid electric trucks.
POWER CONVERTERS CIRCUITS FOR ELECTRIC AND HYBRID ELECTRIC VEHICLES:
The different configuration of EV power supply show that at one Dc converter is necessary to interface the Fc the battery or the supercapacitors module to the Dc link can be designed to transfer power in only one direction from the input to the output. However almost all Dc converter topologies can be made bi_directional. A bi directional converter can move power in either direction which is useful in applications requiring regenerative braking the most common DC\Dc converters can be grouped
NON_ISOLATED CONVERTERS:
BUCK:
A buck converter is a Dc to Dc power converter which steps down voltage from its input to its output it is a class of switched mode power supply typically containing at least two semiconductors a diode and a transistor although modern converters frequently replace the diode with a second transistor used for synchronous rectification and at least one energy storage element combination with are normally added to such a converter output and input.
BOOST:
A boost converter is a Dc to Dc converter that step up votlage from is input to its output. to reduce votlage ripple filters mode of capacitor are normally added to such a converter output and input.
BUCK BOOST:
A buck boost converter is a type of Dc to Dc converter that has on output votlage magnitude that is either greater than or less than the input voltage magnitude it is equivalent to flyback magnitude it is equivalent to a converter using a single inductor instead of a transformer
CUK:
A cuk converter is a type of buck boost converter with zero ripple current. having one switching device and a mutual capacitor to couple the energy
CHARGE PUMP:
A charge pump is a kind of Dc converter that used capacitors for energetic charge storage to raise or lower voltage charge pump circuits are capable of high efficience sometime as high as 90_95% while being electrically simple circuits
ISOLATED CONVERTERS:
HALF BRIDGE:
A half brige converter is a type of Dc to Dc converter that like flyback and forward converters can supply an output voltage either higher or lower than the input votlage and provide electrical isolation via a transformer
FULL BRIDGE:
The bridge converter adds two additional transistors to the haif bridge converter this means that four transistors are available to provide power to the to the ouput section so this type of converter is used in power supplies in excess of 1000 watts. the full bridge converter will be used in larger power supplies usually over 1000 watts. since this type of converter is more complex its normally used in the largest type of power supplies.
PUSH PULL:
A the switch mode power supply has evolved additional adjustments to the original circuits have been made to get more power from smallercomponents. the primary and winding is controlled by two transistors which allow one of them to controlled by two trnsistors which allow one of them to conduct during each half cycle so the output is receiving voltage directly through one of them at all time this means that the efficiency of this configuration is approximately 90% this allows the overall size for the power supply to be smaller for a commparable power supply whose efficiency is 75%to 80%
2.MOTOR AND CONTROLLER PARAMETERS:
Rated armature votlage=72v
Rated armature current=400a
ra=0.5 k=0.7volt second
chopper switching frequency=400hz
the vehicle spped torque characteristics are given the below equation
Tv=24.7+(0.0051)ω..................(1)
duty cycle=70%=0.7
actual votlage =0.7*72=50.4v
we have torque equation for motor
T=50.4.07/0.5-(0.7)/0.5ω
T=70.56-0.98ω
solving equation(1)and (2)
24.7+(0.0051).ω=70.56-(0.98).ω 0.0051ω+0.98ω-45.86=0
the Ev steady state speed if duty cycle is 70%=38.915rad/sec or 371RPM
3.INDUCTION VERSUS DC BRUSHLESS MOTOR:
According to authors perspective firstly he gave the description of Dc brushless motor about its parts and specifications and what is called and next description about induction motor about is component and working of induction motor. hence when used with utillity power they are constant speed mechines. finally when operated from utility power they have limited running peak torque capabilities Dc source or battery and also we can get variable speeds and can adjust the frequencies.
then he discussed as the only main difference between Dc brushless and induction machine when operated with a smart inverter has an advantage over a Dc brushless machine magnetic and conduction losses can be traded such that efficiency is optimized.
That concluded with Dc brush less drives will likely continue to dominate in the hybrid and coming plug in hybrid markets and that induction drives will likely maintain dominance for the high performance pure electrics.
CONCLUSION:
1.Type of power convwerters used in electric and hybrid electric vehicle explained
2.Ev stead speed at 70% duty is 38.915rad/sec
3.Explained in brief what was authors perspective to induction vs brushless motor