UV Light and How UV radiation Kills Microbes

UV Light: Ultraviolet is an electromagnetic radiation which has a wavelength between 100nm to 400nm. UV radiation is not visible to human eye. Lamps, bulb, crackling fire are some examples of objects that emit UV radiation.

source: http://www.lightlab.com/smarter-uv-light/what-is-uv-light

UV region is divided into three bands

  • Ultra Violet A(315-400nm): UVA possess the lowest energy compared to UVB and UVC. It enters deep into the skin causing various skin damages such as wrinkling of the skin, skin cancer and ageing.
  • Ultra Violet B(280-315nm): UVB has the highest energy compared to UVA and UVC. It affects the outer layer of skin causing sunburn, skin cancer and tans.
  • Ultra Violet C (100-280): Highest energy than UVA and UVB. But it doesn’t reach the earth’s surface, it is absorbed by the ozone layer.
source: http://www.arpansa.gov.au/understanding-radiation/what-is-radiation/non-ionising-radiation/ultaviolet-radiation

According to World Health Organization, as sunlight travels through the atmosphere all UV-C and about 90% of UV-B energy are drawn by ozone, water vapour, oxygen and CO2. UV-A radiation is less affected by the atmosphere compared to other two radiation. Therefore, the UV radiation touching the earth’s surface is mainly composed of UV-A with a small amount UV-B factor.

Ultraviolet germicidal irradiation (UVGI) is a decontamination method that uses shorter wavelength UV radiation to inactivate microbes by terminating nucleic acids and disrupting their DNA which makes them powerless to perform certain vital cellular purposes. UVGI is used in a various applications such as food, air purification and water purification.

Killing the microorganisms with UV radiation needs the germicidal wavelengths of between 185 to 254 nanometers. UVC light on earth’s surface is very weak, since the ozone layer blocks it. UVGI devices produces sufficient UVC radiation in air or water systems which breaks apart the derm DNA to make them inactive in environments to microbes such as bacteriaviruses other pathogens. UVC has the strongest germicidal outcome which is very effective in killing or inactivating bacteria, viruses and other pathogens.

A group of single celled microbes which reproduce through the process of cell division are called Bacteria. This single cell feature of bacteria makes it decontaminated by UV radiation as the major form of reproduction in bacteria happens through the process of cell division. Any form of modification in the cell structure of the bacteria can affect the method of cell division.

HOW UV RADIATION KILLS CELLS

DNA is made up of two complementary strands that are twisted together into a double helix structure. This structure is made up of four nucleotides Adenine(A), Thymine(T), Guanine(G) and Cytosine(C). UV radiation kills the cells or the process of cell division by damaging their DNA. When UV light falls on bacteria it initiates a reaction between two thymine molecules, it is one of the bases that form DNA. The subsequent thymine dimer produced is very stable but fixing this DNA damage is by removing the two thymine bases and replacing with new nucleotides, which is not an efficient method.

[Dimers: It’s a chemical compound made up of two identical subunits or monomers]

Extensive exposure to UV radiation results in the formation of more thymine dimers in the DNA which produces an incorrect repair or missing dimer. If the process of cell division is interrupted due to an incorrect repair, missing dimer or any damage then the cell cannot do its normal functions. At this point the cell will die or directs the cell to apoptosis.

CALCULATION OF EXPOSURE TIME REQUIRED FOR DISINFECTION:

The unit of brightness is typically expressed in microwatt per centimeter (μW/cm2) and the exposure time employed for UV sterilization is directly proportional to UV dosage. The mathematical calculations for the same are as shown below.

BATTERY TERMINOLOGIES

Voltage – The potential difference is measured in terms of voltage. The SI unit is a volt and is defined as the measurement of electromotive force, or the difference in potential, which will cause a current of one ampere to flow through a resistance of one ohm.

 How to measure the value of voltage in a cell?

1] Set the multimeter knob to DC voltage measuring mode.

2] Connect the probes into the multimeter.

3] Connect the positive and negative end of the cell to the appropriate probe ends of the multimeter.

4] The voltage value of the cell will be displayed.

Ampere: The flow of electric current is measured in terms of Amperes and its SI unit is Amp.One Amp is defined as the amount of current generated by one volt of electromotive force acting through one ohm of resistance.

Ampere-Hour: The electrical energy stored in the battery pack is measured in terms of Ampere-hour or Ah. The value of current multiplied by time in terms of hours equates ampere-hours. One ampere hour is equal to a current of one ampere flowing for one hour. Also, 1 ampere-hour is equal to 1,000 mAh.

Watt – The total power of the battery pack is measured in terms of watts. Watts is the SI unit for electric power. The wattage of a battery is obtained by multiplying amperes by volts.

Watt-Hour: A Watt Hour is a unit of measurement for power over a period of time. One watt-hour equals one Watt of average power flow over an hour cycle. One Watt of power will be two Watt-Hours for two hours.

Cell – It is an electrochemical device, consisting of positive and negative plates and separated by electrolyte, which is capable of storing electrical energy. It is the basic “building block” of a battery.

Capacity – The capacity of a battery is an indicator or the measurement of the amount of energy that it can deliver in one discharge. Battery capacity is normally mentioned as amp-hours (Ah or mAh) or in terms of watt-hours.

Direct Current (DC) – The unidirectional flow of electric charge. It is the type of electrical current that a battery can supply. One terminal is always positive and the other is always negative.

Cycle – A cycle refers to one sequence of charging and discharging of the battery of its full capacity.

Charge – process of converting electrical energy, given in the form of a current, into chemical  energy and storing it within the cell or battery.

Discharge – The conversion of the chemical energy stored in the battery into electric energy.

Battery-Charge Rate – The rate at which the battery is recharged is known as the battery charge rate and is expressed in amperes (A) or milli amps (mA).

Cycle Life – The total number of charge/discharges cycles a rechargeable cell can sustain before its capacity is significantly reduced is the cycle life of a cell. End of cycle life is commonly considered when the cell or battery only delivers 80 percent of the rated capacity. A battery cycle is greatly influenced by cycle type depth (deep or shallow) and recharging process. Improper cutoff of the charging period will significantly reduce a battery’s cycle life.

Depth of Discharge – The amount of energy that has been harnessed or utilized from a battery (or battery pack). It is usually expressed as a percentage of the total capacity of the battery. For example, 80% DOD means eighty percent of the energy was discharged,  so the battery now only retains 20 percent of its maximum charge.

Energy Density: The volumetric energy storage density of a battery, expressed in Watt-hours per litre (Wh/l).

Power Density: The volumetric power density of a battery, expressed in Watts per litre (W/l).

State of Charge [SOC]: The amount of charge remaining in a cell as a percentage of the charge contained by the cell when it is fully charged. Since, one cannot accurately determine the SOC of a cell without fully discharging it first, the calculation for SOC is usually performed by subtracting the charge removed from the cell so far from the charge contained when it was last charged to 100% SOC.

State of Health [SOH]: It is an indicator of the amount of charge that the cells can hold as they age when compared to its initial stage. In case of Electric Vehicle, the capacity of the cells in the battery pack is the important parameter in determining the range which can be achieved in one charge.

Hence State of Health of an Electric Vehicle battery pack, that is SOHe, which is the amount of charge the cells in the battery pack can hold as they age is  calculated as,

Over a succeeding number of cycles of cells, the capacity of a lithium-ion cell will drop owing to a number of factors including loss of lithium inventory and failing of the electrodes inside the cell. Hence when an aged cell is charged and discharged to its maximum and minimum voltage values respectively, the charge obtained will be lower than charge obtained when the cell was new.

Source: https://www.dukosi.com/blog/what-are-state-of-charge-and-state-of-health/

BATTERY MARKET TREND

The battery is a device that stores energy. It provides power to all the electronic units in the system. Charge storing is relatively uncomplicated but the limitations affect their operation. With growing battery technology, the declaration of new battery type often makes people wonder whether it offers high energy density, high charge, and discharge cycles? Every battery technology has its own pros and cons. It depends on the applications, that is where it is used. Sometimes size and density matter and sometimes the size and safety. The encounter of smaller technology and development of the same gives’way for new possibilities in battery technology.

A battery by definition is a collection of cells. So the cell is a little can of chemicals. And the challenge is taking a very high-energy cell, and a large number of them, and combining them safely into a large battery.”

ELON MUSK

A battery pack has one or more cells and each cell has positive electrode, negative electrode and an electrode between the two electrodes. The properties such as amount of energy stored, power, discharge and charge cycles etc are impacted by the different materials and chemicals used in cells.

The battery market is divided based on battery type that is the primary battery(not-rechargeable) and secondary battery(rechargeable), and the battery technology [Lead-acid, Ni-Cd, NiMH, Li-ion, LiFePO4, and so on], and alsothe application [EV, HEV, PHEV]

Lead-Acid Batteries: They are evolving since its invention in 1859. Lead-acid batteries are used in Telecommunication, UPS and automobile industries. They have seen a great scale of development with respect to the automobile industry.Low maintenance costs, increase in demand for electric vehicles, and lower replacement cost is some of the drivers of lead-acid battery market. Major constraints for the drop in the market is its dependency on hazardous and restricted lead and the shift in the market towards Lithium-ion batteries. The lead-acid battery market is divided into gel battery, AGM battery, and flooded battery. Though the demand share of flooded batteries is anticipated to decrease,due to cost-effectiveness they are in high demand. There is gradual increase in demand share of AGM batteries.

Ni-Cd: In the section of portable battery applications alkaline rechargeable battery market has been expanded with Ni-Cd. They are more efficient than lead-acid batteries. The NI-Cd has low internal resistance and high current conducting properties, thus can be recharged quickly. Ni-Cd battery market is sinking due to the toxic characteristics in Cadmium which affect the environment and also because of other efficient battery technologies trending in the market.

NiMH: They are the upgraded version of Ni-Cd batteries. NiMH has higher energy density per volume and weight than Ni-Cd but at the cost of reduced cycle life. They are used in digital cameras, digital assistance, automotive batteries, cell phones, and other low-cost devices. Disadvantages are highly expensive and high self-discharge. The competition from other battery technologies such as lithium-ion is limiting the growth of NiMH battery market.

Lithium-ion: One of the reasons for the rapid growth in the development of Li-ion batteries is a huge acceptance of these batteries in cell phones, laptops, and computers. Out of all battery types Li-ion provides the highest density and thus electronic manufacturers prefer these over other battery technologies. The applications are categorized into automotive, medical, aerospace, military,consumer electronics and so on. They are also used in renewable energy areas for energy storage purposes. Other advantages such as long lifespan, low self-discharge, high charge, and discharge cycles have added to the growth of lithium-ion battery market

“Lithium makes a fine battery because it’s a scarily reactive metal. Pure lithium ignites on contact if it touches water – a flake of it would sizzle and fry on the water-rich cells of your skin. “

SAM KEAN

The subclass of the lithium-ion battery market is Lithium-Iron-Phosphate[LiFePO4], Lithium-Nickel-Manganese-Cobalt-Oxide [NMC], Lithium-Manganese-Oxide [LMO], Lithium-Nickel-Cobalt-Aluminium-Oxide [NCA], and Lithium-Cobalt-Oxide [LCO] batteries.

Lithium iron phosphate is used for high power applications. Due to the long cycle life, good thermal stability, upgraded safety, and tolerance features,constant voltage the market demand is increasing in consumer electronics and also in EV sectors.

Due to the high energy density, long life span, and thermal stability, the Lithium-Nickel-Manganese-Cobalt-Oxide [NMC] battery market is predicted to witness the highest growth rate. Researchers are working towards reducing the Cobalt content which would further increase the demand.

Lithium Cobalt Oxide [LCO] is one of the most widely used batteries in applications such as cell-phones, laptops, cameras and so on. Hence has increased the global lithium-ion market share.

One of the developing trends in battery technology is Lithium-Sulphur. Some of the aspects of Lithium Sulphur are sulfur is less expensive compared to Nickel, Aluminium, and Cobalt. They are expected to have high densities compared to other battery technologies.

With the rapid growth in the EV industry, the need for a power revolution is always on topic.

“If you want a product that’s thicker with a bigger battery, it’s also heavier, more costly, takes longer to charge. “

–PHIL SCHILLER

“The depressing thing about battery technology is that it gets better, but it gets better slowly. There are a whole bunch of problems in materials science and chemistry that come in trying to make existing batteries better. “

–NATHAN MYHRVOLD

BATTERY

Battery is a device which is used to store the chemical energy and to convert this chemical energy into electrical energy.  The battery is made up of electrochemical cells, which consists of two electrodes, negative and positive electrode and an electrolyte in the center. When the two electrodes are connected by a wire, electrons will flow from negative electrode to positive electrode. This flow of electrons is called electricity. The cell is considered to be dead when the electrons on the positive and negative electrodes are equal. The electrons are generated by chemical reactions and many different chemical reactions are used in batteries. For instance, the disposable batteries, is a non-rechargeable energy storage device which once dead must be disposed, example Alkaline batteries. Thus, rechargeable batteries are used so regular replacement is not required.

Refer https://futuretronlabs.in/blog/index.php/2019/08/22/basic-components-of-an-ev/ to know more about the battery and other EV parts.

The power stored in battery is used to run the electric motor and other electronic units in an electric vehicle. The batteries are recharged from the dedicated charging unit.

TYPES OF BATTERIES

The types of rechargeable batteries used in Hybrid Electric Vehicles and All-Electric Vehicles [EV] are Lead-Acid batteries,Nickel-Cadmium Battery (NiCd or NiCad), Nickel Metal Hydride [NiMH] batteries and Lithium-ion [Li-ion] batteries. Each battery type has its own advantages and selection of these batteries depends on where it is used so that maximum benefit can be obtained.

LEAD ACID BATTERIES

It was invented by Gaston Plante, a French Physician in 1859. To convert chemical energy to electrical energy sponge metallic lead and lead peroxide are used in Lead Acid batteries. It is the oldest and the first rechargeable batteries available.

Some of its advantages are low cost, longest life cycle, it can withstand slow, fast and overcharging, available in all sizes and shapes, wide capacity range, low self-discharge-which is lowest among rechargeable batteries, high discharge rate, can be recycled and reused in new batteries.

Some of its disadvantages are energy density is low, poor weight-to-energy ratio, not environmental friendly, transportation restrictions on flooded lead acid, limited number of full discharge cycles.

NICKEL-CADMIUM BATTERY (NiCd or NiCad) BATTERIES:

Waldemar Jungner invented Nickel-Cadmium battery in 1899. The rechargeable NiCd battery is composed of nickel hydroxide in the positive electrode, cadmium in the negative and potassium hydroxide as electrolyte.  A typical lead-acid battery has cell voltage of roughly 2V, which then steadily comes down as it is depleted whereas NiCad batteries will maintain a steady voltage of 1.2v per cell up till it is nearly completely depleted.

Some of the advantages are low internal resistance, wide range of sizes and performance options are available, high charge and discharge rate, lighter, more compact and higher energy density than lead acid batteries, self-discharge rate is lower than NiMH batteries.

Some of the disadvantages are expensive than lead acid, extremely toxic-causes environmental pollution, high self-discharge, low energy densities compared to newer systems.

NICKEL METAL HYDRIDE[NiMH] BATTERIES:

The Nickel Metal Hydride Battery was patented by Standford Ovshinsky, founder of Ovonics. Hydrogen absorbing alloys are used as the active element at the negative electrode and Nickel -hydroxide at the positive electrode.

Some of the advantages are higher capacity than NiCd, environmental friendly-no toxicity issue, wide operating temperature range, transportation and storage is simple.

Some of the disadvantages are load discharge is high, generates heat during fast charge, sensitive to overcharge.

LITHIUM ION[Li-Ion] BATTERIES

NiMH and Li-ion came into view in 1990s and Li-ion became the most promising and the fastest growing battery system. Lithium offers the largest energy density and is the lightest of all the metals. Due to safety issues attempts to develop Lithium-rechargeable batteries failed. Thus, there was a shift from Lithium to Lithium-ion, it is safer but lower energy density than Lithium metal. The Sony Corporation in 1991 commercialized the first Lithium-ion battery. The electrodes are made of lightweight lithium and carbon. The Lithium-ion has energy density twice that of Ni-Cad Batteries.

Some of the advantages are no memory and no regular discharge is needed – hence low maintenance, high energy density, can handle more charge/discharge cycles, much lighter than other rechargeable batteries,

Some of the disadvantages are protection circuit is required to maintain voltage and current within safe boundaries, very expensive to manufacture, sensitive to high temperatures.

BRUSHLESS DC MOTOR[BLDC MOTOR]

WHAT IS BRUSH-LESS DC MOTOR ?

Also known as BLDC motor or BL motor, it is the DC motor which does not have brushes. Motor is the heart of an Electric Vehicle. It is called Brushless because it doesn’t have brushes and commutator arrangements. Here the commutation is done electronically.

PRINCIPLE OF BLDC MOTOR:

The working principle of BLDC motor is similar to Brushed DC motor. The reversal of current in Brushed DC motor is done by Commutator and Brushes whereas in BLDC motor sensors are used, mostly hall-effect sensors. The hall-effect sensors generate a high or low signal whenever rotor magnetic poles cross the hall sensors, which can be used to detect the position of the shaft.

TYPES OF BLDC MOTORS:

They are classified based on designing and their working procedure is the same.

  • Outer rotor design
  • Inner rotor design
BLDC Motor Types

OUTER ROTOR DESIGN: The rotor of the motor is situated outside and it surrounds the stator which is located in the center of the motor has multi-phase winding. The windings are fed with current and are controlled(commutated) to effect rotation of the rotor. There is no need of external gear system in this type of design and in few instances the motor itself comes with inbuilt gears. Therefore, without any gear system this design makes the device less bulky.  The magnets present in the rotor acts as an insulator and will not allow the heat to dissipate from the motor. Outer rotor designed motor has low torque and operated at low current rates.

INNER ROTOR DESIGN : As in the image the rotor is situated in the centre of the motor and is surrounded by the stator winding. The rotor magnet does not shield the heat inside and the heat will be dissipated effortlessly, thus increasing the torque.

WORKING OF BLDC MOTOR

Working of BLDC Motor

The BLDC motor has 2 main parts rotor and stator. The rotor is the permanent magnet and is rotating part. The stator is the armature winding and is the stationary part. In BLDC motor coils do not rotate as in Brushed DC motor instead they are fixed onto the stator. There is no need of commutator and brushes since coils are static.

Refer https://futuretronlabs.in/blog/index.php/2019/09/25/electric-motor/ to know more about the working of an electric motor.

Mechanical rotation is produced when the magnetic field generated by the permanent magnets(rotor) comes in contact with the field induced by the current in the stator windings. The magnitude and direction of the current into the coils are adjusted to control the rotation.

 Hall effect sensors are mounted on the stator or rotor. As the rotor rotates the hall effect sensors senses the magnetic field and produces a high signal for one pole or low signal for opposite pole. These sensors are connected to the Electronic control unit. Electronic control unit switches the supply voltage between the stator winding as the rotor rotates and energize the correct winding at correct time in such a way that it rotates the rotor around the stator. According to these combinations of signals electronic unit will decide the next commutation sequence or interval to activate.

Some of the advantages of Brushless DC motors are they are highly efficient, exceptional controllability, produce high torque, higher speed range compared to other motors, Operating life is long due to absence of electrical friction losses, Operation is noise-less, high dynamic response. It has power-saving advantages also. Due to its traction characteristics they are most preferred motors in electric vehicle applications.

Reference:

BRUSHED DC MOTOR

WHAT IS BRUSHED DC MOTOR??

One of the simplest types of the motor is the brushed DC motor. The concept behind this motor is when the electrical current is passed through the coils that are arranged inside a fixed magnetic field [N and S]. The current generates magnetic fields in the coils, each coil is repelled from the like pole and attracted towards the unlike pole of the fixed field which causes the coil assembly to rotate. To continue this rotation, the current must be reversed so that the coil polarity will be continuously changed producing the coils to continue chasing the unlike fixed poles.

BRUSHED DC MOTOR

The main components which make Brushed DC motor unique from other motors are brushes and commutator. The power to the coils is provided by the conductive brushes which are in contact with the rotating commutator. Commutator is used to switch the current in the motor windings, and is placed on the axle of the rotor. When the power is given to the brushes which is in contact with commutator, provides power to the windings. This produces the magnetic field around the rotor [Armature]. The rotation of the commutator causes the current to reverse through the coils.

The rotor is pushed away by the stator magnet that is -left part of the rotor is pushed away by left stator magnet towards the right stator magnet; -and the right part of the rotor is pushed away by the right stator magnet towards the left stator magnet. Hence motor is made to rotate continuously by regularly changing the polarity of the magnetic field around the rotor.

Advantages of Brushed DC motor are they are low-cost motors, Easy to Control, Outputs high torque at low speeds.

Disadvantages are maintenance cost is high since brushes and commutators wear quickly and should be replaced when required, electrical noise is more, limited maximum speed because excessive speed will increase the heat.

References:

ELECTRIC MOTOR

What is an Electric Motor??

An Electric Motor  is an  electrical machine that converts electrical energy into mechanical energy.

The History behind an Electric Motor:

The connection between electricity, magnetism, and movement was discovered in 1820 by French physicist Andre-Marie Ampere (1775–1867) and that is the basic science behind an electric motor.

The discoverers who converted this scientific discovery into a practical bit of technology to power electric motors were Englishmen Michael Faraday (1791–1867) and William Sturgeon (1783–1850) and American Joseph Henry (1797–1878). 

The basic idea of an electric motor is simple, electricity is given at one end and at the other end, an axle(metal bar) rotates giving the power to drive any kind of machines.

The principle behind the working of an electric motor is when a current-carrying conductor is placed in a magnetic field it experiences a magnetic field and starts rotating according to the direction given by Fleming’s Left-Hand Rule for a motor.

There are many types of electric motor available in the market and the choice of these motors are very important. Selection of these motors is based on voltage, operation, and application.

TYPES:

Motors are classified based on the power type that is AC or DC and their method for generating rotation.

DC MOTORS

  • Brushed DC motor
  • Brushless DC motor
  • Stepper (STP)

AC MOTORS

  • Induction motor (IM)
  • Synchronous Motor (PM)

Both types of motor have their own advantages and disadvantages:

Comparison between AC and DC motor

IMPORTANT PARTS OF AN ELECTRIC MOTOR:

Important Parts of an Electric Motor

Armature: It is the power generating part in an electric motor. It can be a  rotating part or the stationary part of the machine.  The armature[ABCD] has the rectangular iron core wrapped by copper wire through which current is passed and is placed between the two poles of a magnet. The armature has an axle to which commutator is attached.

Commutator: They are the split rings which reverses the direction of the current. They connect the brushes and coil and are made up of copper. The purpose of the commutator is to make sure that the current direction in the coil reverses every half time so that one side of the coil is pushed downwards and another side of the coil is pushed upwards. The contacts of the commutator are linked to the axle of the armature so they rotate with the coil.  In the above figure, commutator rings are denoted as C1 and C2.

Brushes: They are the two pieces of metal or carbon. One end of the brush is connected to the commutator and other ends of the brushes are connected to the positive and negative terminal of the battery respectively. In the above figure, Brushes are denoted as B1 and B2.

Working of an Electric Motor:

An electric motor uses the magnetic push to rotate the current-carrying conductor.

Magnets S and N will generate the magnetic field that will rotate the current-carrying conductor. Instead of inserting the current-carrying wire, a current-carrying loop [rectangular loop] is introduced as in the figure. Each side of the coil will experience the force and hence the coil starts rotating. To find the direction of the force in each side of the loop Flemings Left-Hand rule for motors(also called motor rule) is used.

Fleming’s Left-Hand Rule:

Fleming’s Left Hand Rule

Hold your thumb, fore and center finger of your left hand such that three fingers are at right angles to each other.

If you point the center finger in the direction of the current and the forefinger in the direction of the field, your thumb will show the direction of motion.

  • Fore-finger = Field
  • Center finger = Current
  • Thumb finger= Motion
Working of an Electric Motor

To begin with, the plane of the rectangular coil ABCD is made parallel to the magnetic field by placing the coil in the horizontal position. Electric current is passed through the rectangular coil ABCD, which enters at A and leaves at D as shown in the figure. When the current is passed AB and CD side of the coil which is perpendicular to the direction of the magnetic field experience force according to Fleming’s left-hand rule. As the current passing through AB and CD of the coil are in the opposite direction, the forces acting on them will also be opposite. Hence forces push AB in downward direction and CD in the upward direction. Thus the coil starts rotating in the anticlockwise direction.

The commutator rings C1 and C2 change their contact from brushes B1 and B2 respectively when the coil completes its half rotation. Because of this, the direction of current in the rectangular coil ABCD is reversed, due to which the direction of forces in the coil is also reversed. Hence side AB is now pushed in upward and CD in the downward direction. Similarly, the whole process is repeated for the continuous rotation of the coil.

Advantages of an Electric Motor:

  • For the same horse-power rating, the initial cost of an electric motor is less compared to fuel engines.
  • An electric motor has comparatively few moving parts and hence longer lifespan.
  • Minimum maintenance is required.
  • Electric motors don’t require fuel, hence there is no need for engine oil maintenance, also no greenhouse gas emissions.
  • Electric motors are highly-efficient with the ratings that range from 50% to 95%.
  •  Wear and tear problems are less.

Refer https://futuretronlabs.in/blog/index.php/2019/08/29/advantages-of-ev/ to know more about the advantages of an Electric vehicle.

References:

REGENERATIVE BRAKING SYSTEM

WHAT IS REGENERATIVE BRAKING SYSTEM?

The technique of recharging the batteries while braking is called Regenerative Braking System.  Regenerative Braking System is used in fully electric vehicles and hybrid electric vehicles that use an electric motor.

HISTORY OF REGENERATIVE BRAKING SYSTEM [1]

  • In 1908, a smart car with Regenerative Braking System was Patented by C.J. Paulson.
  • In 1967 American Motors Cooperation (AMC) in cooperation with Gulton Industries developed the “Energy Regeneration Brake” system.
  • This Energy Regeneration from braking was later commercialized by the Japanese and both Ford and Chevrolet licensed it from Toyota for use in their domestic built hybrid vehicles.
  • During the late 2000s an Electronic Control Unit [ECU] used by BMW that engages the alternator during braking.

WHAT IS THE NEED OF REGENERATIVE BRAKING SYSTEM?

  • Using RBS technique, the fuel economy of vehicles can be improved
  • Reduces greenhouse gas emissions.
  • The increased price of petroleum-based fuels has given way to various research and development in energy conservation.
Normal Driving conditions

In the current world where energy and resource management has become very much important and it’s necessary to employ energy in all the form. Vehicles which are in motion have a lot of kinetic energy and when the brakes are applied all the kinetic energy that was propelling the vehicle forward are lost to the environment as heat which decelerates the car. This useful kinetic energy which could have been used to do some work is wasted as heat.

So, a braking system called Regenerative Braking System [RBS] was introduced, it is an energy recovery mechanism where the kinetic energy is converted into electricity which is used to recharge batteries in Electric Vehicles.

Regenerative action during breaking

Recovering the kinetic energy during braking is called Regenerative Braking System and is used in Electric Vehicles and Hybrid Electric Vehicles [HEV] which make use of an electric motor.

The main components of the Electric Regenerative Braking System are

  • Motor/Generator.
  • Engine.
  • Battery.
  • Electronic Control Unit [ECU].

One of the important properties of an Electric Motor is when it runs in one direction, the electrical energy is converted into mechanical energy which can be used to rotate the wheels of the vehicle. But when the motor runs in the opposite direction, it acts as an electric generator which converts mechanical energy into electrical energy. This electrical energy can be fed into the batteries.

REGENERATIVE BRAKING SYSTEM IN FULLY-ELECTRIC VEHICLE:

Regenerative action in EV

During acceleration, the motor draws the energy from the battery to move the wheels. During braking, the power from the battery is cut off by the controller [ECU] which slows down the motion of the vehicle. Hence the motor performs as a generator and the energy flows back to the battery.

REGENERATIVE BRAKING SYSTEM IN HEV

Regenerative action in HEV

When the driver applies a brake on hybrid electric vehicles, the electric motor generates a negative torque, that is in the reverse direction, which makes the motor act like a generator and thus recovering the energy which is stored in the battery, producing electricity which flows into the batteries.

To gauge the regenerative braking system, its effectiveness and efficiency should be seen. Efficiency states how competently the braking system captures the energy lost when the brake is applied. Effectiveness states how size-able impact(difference) the regenerative braking system actually makes.

BENEFITS OF RBS:

For smaller and personal electric vehicles, the regenerative braking system is not as beneficial or effective as in electric cars, still, it has some multitude of returns.

Regeneration occurs only when the brakes are applied and the resultant energy depends on the speed of the vehicle. By using the Regenerative Braking System, the energy usage efficiency can be increased and also driving distance of Electric Vehicles can be improved. This kind of brakes improves the driving range of Vehicles. All-electric vehicles in motion can utilize this advantage of regeneration to re-collect energy that would have been lost.

Some of the other advantages are the reduction in engine wear out, smaller components, increase the performance, increase in the overall efficiency of vehicles, increases the life span the friction braking system.

Some of the disadvantages are friction brakes are needed to stop the vehicle at low speeds, means energy is still wasted. RBS can increase the overall weight, cost of components, manufacturing and installation are high, maintenance required based on the complexity of the design.

Examples of cars with Regenerative Braking System:

  • Toyota Prius
  • Honda Insight
  • Ford Escape Hybrid
  • Tesla Roadster

References:

  1. https://www.slideshare.net/roskumar18/regenerative-braking-system-37394325
  2. https://auto.howstuffworks.com/auto-parts/brakes/brake-types/regenerative-braking.htm

ADVANTAGES OF EV

Electric Vehicle
Advantages of EV

Some of the advantages of EV are:

LOW MAINTENANCE: Electric Vehicles run on electrically powered engines and hence there is no requirement of lubricating the engines. There is no necessity to send the vehicle to the service station often as with the normal fueled powered vehicles. Petrol or diesel engine has components like exhaust systems, starter motors, fuel injection systems, oil, radiators, gears, etc. connected to it to operate correctly, on the other hand, EV has three main components motor, battery and inverter and few other components which makes maintenance and servicing easier.

REDUCE CO2 EMISSIONS: EVs are eco-friendly as they run on electrically powered motors and can reduce the emissions that promote weather change and smog. As they run on clean energy sources, they do not emit toxic gases in the environment and produces zero exhaust emissions.

REDUCED NOISE POLLUTION: When compared to petrol and diesel vehicles EV has only one moving part that is an electric motor. Hence EVs put a restriction on noise pollution as they are quitter compared to other engines and provides a smooth drive

USING RENEWABLE ENERGY: EV can be recharged using a solar PV system instead of the grid. By using renewable energy greenhouse gas emissions can be reduced further.

COST SAVING: The motor gets the power from charging through AC outlet from home/work-space or from charging stations, no fuel is required and hence can save driving cost.

The Vehicle Cost Calculator can be used to compare life cycle emissions of specific vehicle models in a specified location.

SAFE TO DRIVE: Electric vehicles are very smooth to drive and they do not have engines which cause vibration and noise. Just in case an accident occurs, one can expect airbags to open up and electricity supply to cut from the battery. Hence it prevents passengers in the car from serious damages.

HEALTH BENEFITS: Since harmful exhaust emissions are zero in Electric Vehicle, the air quality is better, which reduces the cost and health issues caused by air pollution.

EV MOTORS ARE MORE EFFICIENT: EV motors can convert nearly 90% of its energy from batteries for the vehicle movement when compared to petrol and diesel vehicle which is 20%-30%. Hence the efficiency of operation is more in electric vehicles.

“In order to have clean air in cities, you have to go ELECTRIC”

Elon Musk 

References:

TYPES OF EV

EVs are classified based on the amount(levels) of electricity used as their source of energy to power the motor. Three main types are

  1. Hybrid Electric Vehicle
  2. Plug-In Hybrid Electric Vehicle
  3. Battery Electric Vehicle
Types of EV

1] HYBRID ELECTRIC VEHICLE: Also called HEV [6-12 KWH]. They are powered by both petrol and electricity, that is a gasoline engine with a fuel tank and an electric motor with a battery. HEVs cannot be recharged from the electricity grid, the electrical energy is generated by the regenerative braking system, that is when pressure is applied on the brakes, the power to motors are stopped. The momentum and kinetic energy make the motor turn the wheels, when brakes are applied the motors work as generators and start producing electricity which flows to the battery. Recharging the batteries while braking is called Regenerative Braking System.  

Regenerative Braking System

HEV starts off using the electric motor, then based on the load or speed required the petrol engine takes over. An internal computer will decide when to use battery power and when to use fuel, thus makes sure the best economy for driving conditions.

Some of the advantages are Longer range compared to BEVs, Less CO2 emissions compared to gas only vehicle.

Some of the disadvantageous are Mechanics is complicated- Gasoline + Electric, Operational cost is very much high compared to BEV but less expensive compared to gasoline vehicle, Cannot connect to an electrical outlet for charging.

Examples of HEV : Toyota Prius, Honda Civic, Toyota Camry

2] PLUG-IN HYBRID ELECTRIC VEHICLE:

Also called as PHEV[6-12KWH]. They are powered by two modes, fuel and electricity. It has an electric motor and battery, which can be recharge using both regenerative braking and ‘plugging-in’ to an external electrical charging port. When the battery is low, they can switch to an internal combustion engine which can also recharge the battery.

Two ways of charging the batteries in PHEV

Plug-In Hybrid Electric Vehicle can be charged by plugging into an electric grid, they have more savings in fuel costs than HEV.

Some of the PHEVs are also called as Extended-Range Electric Vehicle [EREVs]

Advantages are Longer range compared to BEVs, CO2 emissions are less, Gas consumptions are less compared to gas only vehicle.

Disadvantages are CO2 emissions, Operational cost are more than BEVs but less than HEVs.

Examples of PHEV : Ford C-Max Energi, BMW i8, Mercedes C350e

3] BATTERY ELECTRIC VEHICLE: Also called as BEV[20-80KWH]. They run completely using an electric motor and battery without any internal combustion engine. They store electricity on-board with high capacity battery packs which are used to run electric motor and all other electronic components. They must be plugged into an electric grid for charging and can also be recharged using the regenerative braking system.

Battery Electric Vehicle

EV chargers are classified based on the speed with which they recharge an EVs battery.

  • Level 1 Charging.
  • Level 2 Charging .
  • Level 3 or DC Fast Charging .

Level 1 Charging: They use standard 120V outlet to plug into the electric vehicle. It takes over 8hours to charge the battery with a range of around 75-80 miles. This type of charging can be done at the workplace or at home

Level 2 Charging: They use 240V outlet to plug into the electric vehicle. It takes over 4 hours to charge the battery with a range of 75-85 miles. Level 1 Chargers are found at the workplace and public charging stations.

Level 3 Charging [DC Fast Charging]:It is the fastest charging solution in the current EV market. It takes 30 minutes to charge a battery with a range of up to 90miles. They are found at dedicated charging stations.

Some of the advantages are–No CO2 emissions, gas or oil change not required, Can charge at home/work space, Smooth acceleration, Maintenance is easy, Low cost of operation.

Some of the disadvantages are shorter range compared to gasoline vehicles, Moderately more expensive than the gasoline equivalent.

Examples of BEV: Hyundai Kona Electric , Tesla Model 3, Honda Insight, Nissan Leaf

“Electric cars are going to be very important for urban transportation”

Cars have a large engine in the front and you have a gearbox, which is cumbersome. Electric cars don’t have this problem. The motor is much smaller, the battery is below you. This will allow you to play with different shapes

Carlos Ghosn