Ev Charging

Wireless Charging Of Electric Vehicles

Wireless Charging Of Electric Vehicles With the introduction of Wireless Charging Of Electric Vehicles, you no longer need to wait for hours at a charging station. Now you can charge your car by simply placing it in a parking lot or garage, or you can even charge an electric car while driving.

We are very familiar with the wireless transmission of data, audio, and video signals. So why can’t we transmit energy through the air?

Researchers at Cornell University are running a project to charge electric car batteries by moving along a special charging board built into the road. The biggest problem with electric vehicles is the tedious process of finding a charging station when the battery is exhausted, and then spending a lot of time charging it over long distances.

For those who wish to switch to green cars, this question usually comes to mind, and this new research can pave the way for a change in attitudes and the spread of electric cars.

The origin of this idea can be traced back to Serbian-American inventor Nikola Tesla more than 100 years ago, who developed the AC network, which is the main electrical system in the world today. Wireless transmission of power, but failed.

Researchers at Cornell University have developed a system that uses two insulated metal plates on the floor to connect to the power cord. Hardware systems that do not contain ferrite are expected to be integrated more easily and economically on the road.

 How Wireless Charging Of Electric Vehicles is possible?

The basic principle of wireless charging is the same as that of a transformer. During wireless charging, there will be a transmitter and a receiver, which convert 220 V 50 Hz AC power into high-frequency AC, and the high-frequency AC powers the transmitter coil, and then generates an alternating magnetic field.

With the receiver coil, it will generate alternating current flowing in the receiver coil. However, for effective wireless charging, it is important to maintain the resonance frequency between the transmitter and receiver. A compensation network is added to maintain the resonant frequency on both sides.

Finally, the AC power source is converted to DC power on the receiver side and fed to the battery through the battery management system (BMS). Wireless charging systems for electric vehicles can be divided into two categories according to their application areas:

  • Static Wireless Charging
  • Dynamic Wireless Charging

1. Static Wireless Charging

As the name suggests, the car will charge when it is parked. Here, we can simply park the electric car in a parking lot or garage equipped with WCS. The transmitter is installed underground, and the receiver is installed at the bottom of the vehicle. Charge the car, customize the transmitter and receiver, and then charge. The charging time depends on the power level of the AC power source, the distance between the transmitter and receiver, and the size of the contact area. This SWCS is best constructed in a location where the electric vehicle is parked for a period of time.

2. Dynamic Wireless Charging System (DWCS):

As the name implies, the vehicle will charge while it is driving. The energy is transmitted through the air from the stationary transmitter to the receiving coil of the moving vehicle. With DWCS EV, you can continuously charge the battery while driving on roads and highways, thereby extending the driving range. This reduces the need for large energy storage, which further reduces the weight of the vehicle.

Types of  Electric Vehicles Wireless Charging Systems

Based on operating Techniques EVWCS can be classified into four types

  • Capacitive Wireless Charging System (CWCS)
  • Permanent Magnetic Gear Wireless Charging System (PMWC)
  • Inductive Wireless Charging System (IWC)
  • Resonant Inductive Wireless Charging System (RIWC)

1. Capacitive Wireless Charging System (CWCS)

The wireless energy transmission between the transmitter and the receiver is achieved by using the bias current caused by the change in the electric field. Instead of magnets or coils, coupling capacitors are used as transmitters and receivers to transmit power wirelessly.

Power factor correction circuit can improve efficiency and maintain voltage level and reduce power transmission loss. It is then fed to the H bridge to generate a high-frequency AC voltage, and this high-frequency AC current is applied to the drive board to generate an oscillating electric field, which generates a bias current at the board receiver through electrostatic induction.

The receiver voltage on the receiver side is converted into direct current to provide a rectifier and filter circuit for the battery through the BMS.

Frequency, voltage, the size of the blocking capacitor, and the air gap between the transmitter and receiver will affect the energy emitted. The operating frequency range is 100 to 600 kHz.

2. Permanent Magnet Gear Wireless Charging System (PMWC)

Here, the transmitter and receiver are composed of armature windings and synchronous permanent magnets in the windings. Viewed from the side of the launcher, its operation is similar to that of an engine.

When we apply alternating current to the transmitter coil, a mechanical torque is generated. Place it on the magnet of the transmitter and make it rotate. By changing the magnetic interaction in the transmitter, the PM magnetic field induces a torque in the PM receiver, causing it to rotate synchronously with the transmitter magnet.

The change in the constant magnetic field of the receiver now results in the formation of alternating current in the windings, ie the receiver acts as a generator because the mechanical power provided by the receiver to the PMT is converted into electrical energy.

The connection of rotating permanent magnets is called magnetic transmission. The alternating current generated on the receiver side is rectified and filtered by the rectifier to power the battery.

3. Inductive Wireless Charging System (IWC)

The basic principle of IWC is Faraday’s law of induction. Wireless energy transmission is achieved by mutual induction of magnetic fields between the transmitter coil and the receiver coil.

When the main AC power is applied to the transmitter’s coil, it will generate an AC magnetic field flowing through the receiver. The coil and this magnetic field move the electrons in the receiving coil and produce AC output.

The AC output is rectified and filtered to charge the energy storage system of the vehicle. The transmitted energy depends on the frequency, mutual inductance, and the distance between the transmitter and receiver coils. The IWC frequency is 19 to 50 kHz.

4. Resonant Inductive Wireless Charging System (RIWC)

Basically, high-Q resonators transfer energy at a faster rate. Therefore, if we can also resonate in a weaker magnetic field, then we can deliver the same amount of energy as IWC. Energy can be transmitted over long distances without cables. When the transmitter and receiver coils are matched, energy is generated in the air. H. The resonant frequencies of the two coils must match.

Therefore, in order to obtain a good resonance frequency, additional compensation circuits are added to the transmitter and receiver coils in a combination of series and parallel. The additional compensation circuit and the improved resonance frequency reduce the additional loss. The operating frequency of RIWC is 10 to 150 kHz.

Companies Currently Developed and Working on WCS

  • Evatran Groups provides plug-in charging for light electric vehicles such as Tesla Model S, BMW i3, Nissan Leaf, and Gen 1 Chevrolet Volt.
  • WiTricy Corporation cooperates with Honda Motor Co. to produce WCS for passenger cars and SUVs. Nissan, General Motors, Hyundai, Furukawa Electric Co., Ltd.
  • Qualcomm Halo produces WCS for passenger cars, sports cars, and racing cars and was acquired by Witricity Corporation.
  • Hevo Power manufactures passenger car WCS
  • Bombardier Primove produces WCS for passenger cars and SUVs.
  • Siemens and BMW created WCS for passenger cars.
  • Momentum Dynamic manufactures WCS Corporation for fleets and commercial buses.
  • Conductix-Wampfler produces WCS for industrial parks and buses.

Challenges Faced by WEVCS

Since the current location is not suitable for these facilities, new infrastructure is needed to install static and dynamic wireless charging stations on the street. According to human safety and health standards, it is necessary to maintain electromagnetic compatibility, electromagnetic interference, and frequency.

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