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Wednesday, December 18, 2024

Major types of Electric Vehicles in the world

               Nexon EV     mahindra be6e


Several types of electric vehicles (EVs) are available in the market, each with unique characteristics and ways of using electricity as a power source. Here's a breakdown of the main types:  

1. Battery Electric Vehicles (BEVs)  or Pure EVs

  • How they work: These are "pure" electric vehicles that run solely on electricity stored in a battery pack. They have no internal combustion engine (ICE).  
  • Key features:
    • Plug-in charging: BEVs are plugged into an external power source (charging station or wall outlet).  
    • Zero tailpipe emissions: They produce no emissions from the vehicle itself.  
    • Examples: TATA Nexon, TATA Tiago, Mahindra XEV 9e and BE 6e, Tesla Model S etc...

2. Hybrid Electric Vehicles (HEVs)

  • How they work: HEVs combine an electric motor with a traditional internal combustion engine (usually gasoline). The electric motor assists the engine, improving fuel efficiency.  
  • Key features:
    • Regenerative braking: HEVs capture energy during braking and use it to recharge the battery.  
    • Cannot be plugged in: The engine and regenerative braking charge the battery, not an external source.
    • Examples: Maruti Grand Vitara, Toyota Innova Hycross, Honda City e: HEV

3. Plug-in Hybrid Electric Vehicles (PHEVs)

  • How they work: PHEVs are similar to HEVs, but they have a larger battery pack and can be plugged in to charge. They can also drive for a certain distance on electric power alone.  
  • Key features:
    • Dual power sources: Can run on electricity, gasoline, or a combination of both.
    • Longer electric range than HEVs: Allows for some emission-free driving.  
    • Examples: Chevrolet Volt, Toyota Prius Prime, Mercedes AMG GT 63 SE and BMW XM.

4. Fuel Cell Electric Vehicles (FCEVs)  

  • How they work: FCEVs use a fuel cell to generate electricity from hydrogen. They combine hydrogen with oxygen from the air to produce electricity, with water as the only byproduct.  
  • Key features:
    • Refuelled with hydrogen: Similar to refuelling a gasoline car, but with hydrogen instead.
    • Zero tailpipe emissions: Only emit water vapour.
    • Examples: Toyota Mirai, Hyundai Nexo


BEV

HEV

PHEV

FCEV

Power Source

Battery only

Engine + Electric Motor

Engine + Electric Motor + Plug-in Charging

Hydrogen Fuel Cell

Charging

Plug-in

Self-charging

Plug-in + Self-charging

Hydrogen refueling

Range

Long

Short

Medium

Long

Tailpipe Emissions

Zero

Reduced

Reduced/Zero (in EV mode)

Zero

Tuesday, December 17, 2024

What is Resolver in Electric Motor & How it Works?

AI-Generated Motor Resolver to determine the position of the rotor.
AI-Generated Motor Resolver to determine the position of the rotor.

                             

The resolver is an electromechanical transducer or a rotary transformer that determines a motor's rotor position. The resolver is sometimes called as a Control Transmitter or Analog Trigonometric Function Generator.

The resolvers were initially developed for military applications to withstand harsh environments. Wherever we need to find the angular position of a rotary shaft we can use resolvers to measure it accurately and reliably.

Encoder:

Don't confuse a Resolver with an Encoder, Both are used to measure the speed and angular position of the rotating shaft, the main difference is the resolver is a mechanical device & the encoder is an electrically operated device and the output is analog in nature for resolver and digital in the encoder.


Let's dive deeper into how a resolver works.

Core Principle: Electromagnetic Induction

At its heart, a resolver functions based on the principle of electromagnetic induction, just like a transformer. This means that a changing magnetic field can induce an electrical current in a nearby conductor.

Think of it like a very precise dial:

  • Imagine a dial that can tell you exactly how far it has turned. A resolver does something similar, but instead of a physical dial, it uses electrical signals.
  • It has two main parts: a rotor (the part that turns) and a stator (the stationary part).
  • These parts have wire coils that create magnetic fields. As the rotor turns, these magnetic fields change.
  • These changes in the magnetic fields produce electrical signals that can be used to precisely determine the angle of the rotor.

Components:

  1. Rotor: The rotating part of the resolver, typically with a single winding (coil of wire) called the excitation winding or primary winding.
  2. Stator: The stationary part, usually with two windings placed at a 90-degree angle to each other. These are called the sine and cosine windings or secondary windings.

Working Mechanism:

R - Rotor (Excitation Winding)
S1 - Stator Winding
S2- Stator Winding

Note: The resolver's output is two sine and cosine waves that have a 90 electrical degree phase difference with respect to the reference voltage given in the Primary Excitation Winding.

Excitation:
An AC (alternating current) voltage is applied to the rotor's excitation winding. This creates a magnetic field within the resolver.

From where the voltage is supplied from:
  • Resolver-to-Digital Converter (RDC): An RDC is a specialized integrated circuit (IC) designed specifically to work with resolvers. It does several key things:

    • Generates the AC excitation signal: The RDC produces the precise AC voltage at the correct frequency and amplitude needed for the resolver's reference winding.
    • Processes the resolver's output signals: The RDC takes the sine and cosine signals from the resolver and converts them into a digital representation of the angle.
A simple electronic oscillator circuit can generate an AC signal. However, this is less precise and flexible than an RDC.

RDCs are designed to provide a very stable and accurate AC signal, which is crucial for precise angle measurement.

Magnetic Field Interaction: As the rotor turns, its magnetic field interacts with the stator windings. The strength of this interaction changes depending on the rotor's angular position.

Induced Voltages: This interaction induces AC voltages in the stator windings. The amplitudes (strengths) of these voltages vary sinusoidally with the rotor's angle.
  • The voltage induced in one stator winding is proportional to the sine of the rotor angle.
  • The voltage induced in the other stator winding is proportional to the cosine of the rotor angle.

    Mathematical Representation:

    If the excitation voltage applied to the rotor is:

    • V_excitation = V_peak * sin(ωt) (where ω is the frequency of the AC signal)

    Then the voltages induced in the stator windings are:

    • V_sine = K * V_peak * sin(ωt) * sin(θ)
    • V_cosine = K * V_peak * sin(ωt) * cos(θ)

    Where:

    • K is a constant related to the resolver's construction.
    • θ is the angle of the rotor.

    Determining the Angle:

    By measuring the amplitudes of the sine and cosine voltages from the stator, the angle θ can be precisely calculated using trigonometric relationships.

    Still confused about resolver, here is an analogy:

    Imagine a flashlight inside a tube.

    • The tube: This is like the body of the resolver.
    • The flashlight: This is like the "reference winding" in the resolver. It sends out light (or in the resolver's case, an electrical signal).
    • Two light sensors on the tube's wall: These are like the "sine and cosine windings." They measure how much light hits them.

    Now, imagine you can rotate the flashlight inside the tube.

    • When the flashlight points directly at one sensor, that sensor gets the most light. The other sensor gets very little.
    • As you rotate the flashlight, the amount of light hitting each sensor changes. Sometimes one gets more, sometimes the other.

    This is similar to how a resolver works:

    • The "flashlight" (reference winding) sends out an electrical signal.
    • As the resolver's shaft rotates, it changes how much of that signal reaches the two "sensors" (sine and cosine windings).
    • The amount of signal each sensor receives follows a sine wave and a cosine wave pattern as the shaft turns.
    Hope you get an idea of how a resolver works inside an edrive or motor.

    Why are resolvers used?

    Resolvers are popular in applications where accuracy and reliability are crucial, such as:

    • Robotics: To precisely control the movement of robotic arms.
    • Aerospace: In aircraft control systems and navigation.
    • Industrial automation: In machines that require precise positioning.
    • Electric vehicles: To accurately control the motor and ensure smooth operation.

    Advantages of resolvers:

    • High accuracy: They can provide very precise measurements of rotation.
    • Robustness: They can withstand harsh environments, including high temperatures, vibration, and shock.
    • Reliability: They have a long lifespan and require minimal maintenance.

    In essence, a resolver is a robust and accurate sensor that provides precise information about the rotational position, making it essential in various demanding applications.











    Monday, December 16, 2024

    What are the do's and dont's to keep Lithium Ion battery Safe & Healthy?

     

    Lithium Iron Phosphate (LiFePO4) cells arranged in parallel to increase capacity; 3.2V 700AH

    The industry follows some dos and don'ts for the safe operation of LFP(Lithium Ferrous Phosphate) or any other lithium-based batteries, which are as follows.

    Do's:

    1. Store at Ideal SOC: Always store lithium batteries or EV batteries at an ideal state of charge (SOC) between 40% and 60% for longer periods.

    2. Hazardous Safety: Keep the batteries away from hazardous materials, such as fire, oils, explosives, and similar substances.

    3. Adequate Ventilation: Ensure adequate ventilation if storing more than one lithium battery in a single location.

    4. Optimal temperature: Store lithium batteries at an optimal temperature range of 20°C to 45°C.

    5. Optimal Charge: Charge the EV battery or vehicle to 100% SOC at least once a week to calibrate the Battery Management System (BMS) for SOC correction.

    6. Physical Verification: During general service checks at the dealership, inspect for any dents or rust underneath the tray of the lithium battery.

    Don'ts:

    1. Avoid Using Incompatible Chargers: Do not charge lithium-based batteries with chargers meant for VRLA or lead-acid batteries. Always use the charger provided by the original equipment manufacturer (OEM), or ensure that any alternative charger is equipped with the appropriate charging methodology for lithium batteries.

    2. Optimal State of Charge (SoC): Lithium-ion batteries should be stored at 50% to 60% of their state of charge for long durations (2 to 4 months). Additionally, it's important to top up the charge every 6 months if the battery is not in use.

    3. Charging Speed Matters: Avoid ultra-fast chargers, as they can impose high stress on the battery and reduce lifespan. While occasional fast charging is acceptable, it’s always preferable to use slow charging methods.

    4. Regular Charging: Users should charge the battery to full at least twice a week and ensure that the state of charge does not drop below 20%. Both high and very low SOC can damage lithium battery cells.

    5. Temperature Considerations: Do not charge the battery in extremely cold temperatures. 

    By following these guidelines, you can ensure safer and more reliable operation of lithium-based batteries.


     


    Saturday, December 14, 2024

    What is an Electric Motor and its workings in detail ?

     

    Gemani Motor,AI Motor,Electric Motor,EV Motor,PMSM motor
    Image 1: AI Generated EV vehicle electric motor

    To know about basics of electric motor , Lets rewind the basics of Physics which will be useful for this topic.

    Fundamental Physics:


    1. Force: A Push or Pull experinced by any object is called a force.

    2. Current: Movement of electrons in a conductors causes current to flow from higher potential to lower Potential ( Like Water as a current moves from Tank to a small Tap).

    3. Electron: Electron is a fundamental subatomic particle and , it is also known as an elementary particle because it can't be break into any other sub particle.

    Electron flows from Negative of the power source to the Positive, Since electron have -ve Charge and only electron moves in an atom unlike Proton & Neutron so the movement of electron will be from Negative to Positive in a source like Battery.

    4. Magnetic Field: It is an invisible Force (Lorentz Force) that an Object or Charge carriers (Electrons,Holes,Ions) experinces around a magnetic material like Magnets.

    5. Fleming's Left Hand Rule:
    Fleming's Left Hand Rule
    Image 2: Fleming's Left Hand Rule Rajiv1840478, CC BY-SA 4.0, via Wikimedia Commons

    As shown in the above image,The Fleming's left hand rule is applicable only for Motors, Which says whenever an conductor placed in a magnetic field the conductor experinces a Force (F) which will be perpendicular to the dirction of  Magnetic Field (B) and the Current (I).

    6. Fleming's Right Hand Rule: 
    Fleming's Right hand rule
    Image 3: Fleming's Right Hand Rule , Douglas Morrison DougM, CC BY-SA 3.0


    As shown in the above image (2),The Fleming's right hand rule is applicable for Generators, Which says whenever an conductor is moved in a magnetic field an emf will be induced across the conductor and if the conductor is in a closed path or loop then the induced emf will cause a current to flow.

     The Direction of movement of Conductor (F) which will be perpendicular to the dirction of  Magnetic Field (B) and the Current (I).


    DC Motor:

    Image 4: Rotation of Rotor inside an Electric Motor 

    A Motor is a device which converts input electrical energy to output mechanical energy. 

    Components of a Simple DC Motor:

    A Motor consists of major components which are,

    1. Stator (D) - It is a static segment of a motor in which magnetic fields are created by Permanent Magnet or Electromagnet.
    2.Rotor/Armature (C) - It is a rotating segment of a motor which is made up of steel,copper coils and a shaft.
    3.Commutator (A) - It is a segment of the rotor in which the terminals of the rotor winding is conneted which periodically revereses the direction of the supplied current through brushes.
    4.Brushes (B) - It is used to transfer power from the fixed electrical contact or wire to the rotating commutator.



    Image 6: Electric Motor working Principles



    Working of a Electric Motor:

    The above image is a simple model that explains the working of an electric motor.

    The Magnets magnetic fields always travel from Northpole to Southpole outside magnets and from S to N inside the magnets.

    The Magnetic field lines are drawn from N ----> S that is denoted as letter (B) in the above image.
    Direction of Force exerted is denoted by letter (F) & Current as (I).

    As per Feradays Left hand Rule which is applicable only to Motors, When we supply power to the armature carrying coils, a magnetic field will be generated and interacts with the stators magnetic field since the opposite poles of the magnets attracts each other the rotor starts to rotate a half. 

    But there is an issue still not seen , The Motor can't rotate another half because the magnetic field of rotor and stator is in parellel and alligned now.

    The solution is to either flip the magnets or to flip the power source like battery for every half cycle but the easier and the effective method to resolve this problem is to introduce a segment called Commutator.

    The commutator is a circular split type ring and its job is to flip the polarity of current supplied through the brushs. The brush is a fixed contact or a metal piece which will be in contact with the commutator always.

    The Commutator rotates with the armature or rotor but the power supplying brushes are in fixed position so that the polarity of current is fliped for every half rotation.

    This resolves the issue and the motor will rotate contineously. 

    The torque of the motor can be varied by either improving the strength of the magnetic field by increasing the cross section of the coil or by increasing the number of turns of the coil or by increasing the current flowing through the coil.








    Thursday, December 12, 2024

    What are IP Ratings?Types of IP ratings

                                               

    What are IP Ratings?

    IP rating or Ingress Protection Rating are the indicator which defines the protection of electrical or Mechanical enclosures Components from the external Intruders like Water,Dust,Oil splash etc...

    or simply IP Ratings shows how any enclosure is protected against Water and Solids.

    The IP rating has a two digit number after a letter IP X X (X)--->optional

    IP - Ingress Protection

    X - Solids ( Dust,sand etc..)

    X - Liquids ( Moisture,Oils,Water etc..)

    X - Pressure (Optional)

    Note: The Higher the number after IP ,the better the Protection.


    IP Ratings
    IP Ratings