Application of Power Electronics in Automotive Applications

Application of solid-state devices such as diode, silicon-controlled rectifier (SCR), thyristors, gate turn-off thyristors, TRIAC, bipolar junction transistor (BJT), Power MOSFET and so on for control and conversion of electric power is called as power electronics. Application of power electronics in automotive applications plays a major role in controlling automotive electronics. Automotive electronics include modern electric power steering, HEV main inverter, central body control, braking system, seat control, and so on.

Why Power Electronics are Used in Automotive Applications?

In our day-to-day life, we frequently observe heat radiating from car engine after the car has been driven for a certain distance. This is due to power train system of automotive electronics with an engine or internal combustion or motor as one of the subsystem operating with high temperature exceeding 125 degrees Celsius. Application of power electronics with components such as silicon-based power MOSFETs and IGBTs that are used as power electronic switches in the power train system of automotive electrical and electronic systems for reducing the overall size. And also for managing thermal issues in which a high power of kW range is being used for improving fuel efficiency.

Limitations can be overcome by using a wideband gap semiconductors like silicon carbide with a high-operating temperature that allows placing the circuit near high temperature location. It has two or three times higher thermal conductivity than silicon, which will eliminate need of big copper blocks and water jackets. Silicon carbide has high breakdown voltage and capable of switching at high frequencies with very less power loss which makes the overall size of circuitry very small.

Application of Power Electronics

Power electronics applications are extended to various fields such as Aerospace, Automotive electrical and electronic systems, commercial, industrial, residential, telecommunication, transportation, utility systems, etc. In case of automotive electronics, the electrically-generated systems are used in automobiles such as road vehicles like telematics, in-car entertainment systems, carputers, and so on. The need to control engines of automobiles originated in automotive electronics for proper controlling and conversion.

Automotive electronics are classified into different types: engine electronics, transmission electronics, chassis electronics, active safety, driver assistance, passenger comfort and entertainment systems. For any power system such as DC/DC or DC/AC or AC/DC, the power electronic components like controllers, gate drivers, converters and so on are required. Generally, based on the vehicle or power supply manufacturer requirements the analog or digital controllers are chosen such that the following parameters including cost, integration, reliability and flexibility are taken into consideration.

Power Electronics Application in Automotive Electronics

Applications of power electronics in automotive electrical and electronic systems includes high voltage systems, automotive power generation, switched mode power supply (SMPS), DC to DC converters, electric drives, traction inverter or DC to AC converter, power electronic component, high temperature requirement, application of SMPS in power train system, and so on. For example, consider a modern car, in which we can find many power electronic components such as ignition switch, control module, vehicle speed sensor, steering sensor and other components, as shown in above figure.

1. Automotive Power Generation

Application of power electronics in the automotive power generation system provides automotive alternators with improved efficiency and high power, along with high temperature withstanding capacity and high-power density with a variety of research in designing of alternator with a switched mode power electronics applications. The frequently used alternator in automotive applications is Lundell or Claw-pole alternator, as it is suitable for the required emerging performance. Field and armature characteristics of this alternator are enhanced by the use of power electronics. These alternators are used in automobiles for supplying power to the batteries and electrical system while the engine is running. Automotive alternators require a power electronic voltage regulator for producing a constant voltage at the battery terminals by modulating small field current.

2. Switched Mode Power Supply (SMPS)

SMPS concept is based on the power electronics devices such as semiconductor devices that operates in an on state that has zero voltage and an off state that has zero current during this state theoretically with 100% efficiency. To switch these power semiconductor devices on and off the pulse width modulation (PWM) technique is used. Less bulky and small-sized power electronics based converters are used for high frequency switching as these switches are capable of operating under high switching frequencies.

SMPS Applications in the Power Train System

The power train systems of HEVs, electric vehicles and ICE need the following SMPS conditioners such as:

• Regenerative braking (AC/DC)
• On-board charger (AC/DC)
• Dual-battery system (DC/DC)
• Traction motor (DC/AC)

3. DC to DC Converters

There are different DC to DC converter topologies available which can be used based on the requirements. These topologies are classified as isolated and non-isolated topologies which are adopted in power train systems. The application of power electronics in switching has brought a concept of soft-switching where the switches are subjected to low stress using an LLC or resonant mode. These soft-switching, highly reliable and longlife converters are very useful in the automotive electronics market. There are bidirectional converters such as 400 to 12V for electric vehicles and 48 to 12V for hybrid electric vehicle or internal combustion engine.

4. Traction Inverter (DC/AC)

Electrical motors are machines used for converting electrical energy into mechanical energy and primarily DC motors are used for this purpose, but due to the unreliability of DC motors, AC motors are used because of their efficiency. Application of power electronics in building controllers for AC motors has tremendous progress from the past two decades. Thus, for AC motors to supply power, power stored in batteries of the automotive electrical and electronic systems of electric vehicles or hybrid electric vehicles or ICE require the application of power electronics such as DC to AC converters or electrical inverters.

5. On-board Charger (AC/DC)

Vehicles with automotive electronics consist of batteries that need to be charged; for this charging purpose, the supply AC power has to be converted into DC. We know that, the power can be stored in batteries only in the form of DC. This conversion of AC to DC can be done by the application of power electronics converters called as rectifiers.

The application of power electronics is increasing with the advancing technologies in automotive electrical and electronics systems for improving the overall system efficiency with high operating temperature, increasing flexibility, reliability and to reduce the overall size of the circuitry. If you know any new innovative applications of power electronics in automotive electronics, then post your ideas and comments in the comment section below.

Photo Credits:

• Power Electronics in Automotive Applications by electronicdesign
• Silicon based Dual Channel MOSFET by siliconray
• Silicon Carbide Chip by hybridcars
• Automotive Electronics Components by omron
• Power Electronics Application in Automotive Electronics by clemson
• Cut view of Lundell Alternator by wikimedia
• SMPS by aliexpress
• DC-DC Converter by diytrade
• Automotive Batteries by imimg