Onboard Charger for Electric Vehicle

Project Title

Onboard Charger for Electric Vehicle

Project Area of Specialization Electrical/Electronic EngineeringProject Summary

One of the major sources of environmental pollution is gas-powered vehicles. An electric vehicle is a great alternative to gas-powered vehicles. in recent years electric vehicles reached such an advancement in technology that they can compete with gas-powered vehicles.

The only drawback is that they can be used for a shorter distance. This inconvenience is because they require hours to charge their batteries and a special unit known as a charging station where you can plug your vehicle for charging.

Charging an electric vehicle requires a lot of energy to charge its batteries. An energy converter can help in the conversion of this energy. These energy converters may have a large number of energy processors. These components are not convenient enough to be placed inside a vehicle.

A resonant power conversion technique can lead to smaller, more efficient, lighter, less expensive, and more reliable energy converters. These converters are small and light enough to be placed inside an electric vehicle.

There are two types of chargers, On-Board (inside the vehicle) and Off-Board (outside the vehicle). Our project is based on On-Board charging of electric vehicles. For this charging technology we are using LLC (inductor-inductor-capacitor) Charging topology.

The LLC (inductor-inductor-capacitor) converter is a resonant inverter with three reactive elements where the DC input voltage is turned into a square wave by a switch network arranged as either a half-or full-bridge to feed the resonant LLC tank that effectively filters out harmonics providing a sinusoidal like voltage and current waveform. This in turn feeds a transformer that provides voltage scaling and primary-secondary isolation. The converter power flow is controlled by modulating the square wave frequency concerning the resonance of the resonant tank circuit.  In an LLC resonant converter, all semiconductor switches are soft-switching, or zero-voltage switching (ZVS), at turn-on for the primary MOSFETs and zero-current switching (ZCS) at both turn-on and turn-off for the rectifiers in the secondary, resulting in low electro-magnetic emissions levels (EMI). In addition, it can enable the design of converters with higher efficiency and power density.

The circuit will be similar to this circuit diagram,

Project Objectives

• To design a 1kW On-Board Charger for Electric Vehicle with 90% Power Efficiency. This efficiency can be achieved by using LLC (inductor-inductor-capacitor) charging topology. By using the ZVS technique and phase-shifted pulse width modulation (PWM) control, the efficiency can be increased even further.
• Reduce Electromagnetic Interference by 90% to that of non-Resonant-based chargers. ZVS (zero volt switching) at high frequency improves EMI (electromagnetic interference) behavior. It has continuous input current and small current ripple, which can reduce the EMI pollution and improve the reliability of the converter.
• Reduce the size of the On-Board charger by 50% as compared with non-Resonant-based chargers.
• Reduce Switching Stress by using Zero Volt Switching and Zero Current Switching. The voltage stress on the switches is reduced to half of the input voltage, thus it is suitable for high power conditions and for use in narrowing the switching frequency range.

Project Implementation Method

By adequately designing the LLC resonant converter, the parasitic components can serve as the resonant tank, which is helpful for reducing the overall volume of magnetic components. Also, soft-switching from no-load to full-load condition is achieved. Other advantages of LLC converters are that they are easy to design within a wide range of input voltage levels, and they offer high power factor and high efficiency. The proposed model consists of the following components:

• A switching bridge.
• LLC tank.
• Transformer and Rectifier.
• Output capacitor.
• Arduino.
• Load

Block Diagram:

Simulations:

Hardware Prototype:

Hardware Output:

Benefits of the Project

The project will help to reduce power losses in traditional chargers. Due to its low weight, it can be transported easily or can be installed inside the vehicle.

The key features of this project are:

• The battery can be charged anywhere with a normal 220-volt wall socket.
• Reduced Power loss due to zero volt switching.
• Available for everyone in the market because of the simple circuit.
• One-time installation (No need for maintenance). Installed inside the vehicle just like an ECU. Requires electricity operation.
• Environment Friendly. utilized in environment-friendly electric vehicles that do not produce any emissions. The charger is emission-free.

Technical Details of Final Deliverable

There are three operation modes:

1. Charge Depletion (CD) Mode

During this operation mode, the net energy stored in batteries will decrease over a driving profile. The depletion process will be ended at about 20% SOC.

1. Charge Sustaining (CS) Mode

During this operation mode, the net energy stored in batteries may increase and decrease over a driving profile. However, by the end of the operating duty cycle, the energy stored in batteries will be the same as that at the beginning of the period.

1. Regular Recharge Mode

In this mode, the batteries will be recharged by plug-in outlet. The grid ac energy is then converted to dc energy stored in the batteries. Usually, the recharge mode will be ended at 100% SOC.

From the analysis, the DC characteristic of LLC resonant converter could be derived. Based on the DC characteristic, parameters in power stage can be designed. The parameters need to be designed are:

• Input voltage range: 220V AC
• Output voltage: 55V  DC
• Maximum load: 1000W
• Maximum switching frequency: 50khz

The proposed onboard charger is contained two stages one is the full-span LLC thunderous converter stage and the other is the help PFC converter stage. The block outline of the proposed two-stage onboard charger is displayed in the figure below

Block Diagram of On-Board Chrager for Electric Vehicle

Furthermore, the schematic of the proposed circuit is displayed in the figure. It has

the opposite construction to customary chargers.

Full Bridge Resonant Converter

Mathematical Model:

EMI Filter

	Vout=Vin[Xc12?fC+2?fC]  Vout=Vin[12?fC ×2?fC1+2?f2LC] ?Xc=12?fC Vout=Vin[11+4?2f2LC]  VoutVin= 11+f2fc22   VoutVin= 11+ffc4     ………(1) Where,     fc=12?LC

VoutVin=0.1  Using equation..(1) 0.1= 11+10×103fc4  0.01= 11+10×1014fc4  0.01+10×1014fc4=1  fc=3173 Hz fc=12?LC

  

Vout=Vin[Xc12?fC+2?fC] 

Vout=Vin[12?fC ×2?fC1+2?f2LC] ?Xc=12?fC

Vout=Vin[11+4?2f2LC] 

VoutVin= 11+f2fc22  

VoutVin= 11+ffc4     ………(1)

Where,     fc=12?LC 

VoutVin=0.1  Using equation..(1) 0.1= 11+10×103fc4  0.01= 11+10×1014fc4  0.01+10×1014fc4=1  fc=3173 Hz fc=12?LC

VoutVin=0.1 

Using equation..(1)

0.1= 11+10×103fc4 

0.01= 11+10×1014fc4 

0.01+10×1014fc4=1 

fc=3173 Hz

fc=12?LC

Final Deliverable of the Project HW/SW integrated systemCore Industry EducationOther IndustriesCore Technology OthersOther TechnologiesSustainable Development Goals Affordable and Clean Energy, Climate ActionRequired Resources

Vout=Vin[Xc12?fC+2?fC]  Vout=Vin[12?fC ×2?fC1+2?f2LC] ?Xc=12?fC Vout=Vin[11+4?2f2LC]  VoutVin= 11+f2fc22   VoutVin= 11+ffc4     ………(1) Where,     fc=12?LC