Many automotive engineers got great background working for many companies producing classic internal combustion engine vehicles. There are many things related to electricity with classic vehicles like engine ignition system, powering auxiliary lights and many other electrical devices. So, these genuine issues related to car electrical systems are present way back from the first classic vehicles. Although there are great many differences in concept of complete propelling the vehicle with electric motors and helping to propel. Electro technology related to car production got great and very dynamic changes during time. Many electric devices is helping classic internal combustion vehicles to move more safely, to gather more information of what’s going on in all vehicle’s systems, to make travel more powerful and more comfortable. Complete operating of today’s “classic” vehicles is unimaginable without using great deal of electro components. They are everywhere. In the engine, near the engine, in cooling and heating systems, steering systems, braking and so on. Braking and steering systems are rapidly moving to electric control and electromagnetic power these days. So implementing electrical energy into vehicles got home ground with ages. It’s only natural to use electrical energy to completely propel the vehicle without need of internal combustion engine. It could be done with great positive impact to environment and to whole mankind. Pollutants and noise can, and will be in the past memory of future mankind.

Electric motors that nowadays are used to propel electric and hybrid vehicles got some characteristics differing from industrial electric motors. Motors used in vehicles need to satisfy many conditions. Frequent starts and stops, high ratio of acceleration and deceleration, low torque on high speed movement, high torque on low speed climbing. The electric motor propelling electric and hybrid vehicles can be sort into 2 groups:

commutator motors

commutatorless motors

Commutator motors usually represent traditional DC motors. They can provide great deal of adjustable speed, frequent starting, stopping and reversing. Principle in DC motors operation is straightforward and it consists of field system (stationary) and armature commutation system (rotating).

The performance of DC motors, practically can be expressed by the armature voltage, field flux and electromotive force.

Typically, there are four types of wound-field DC motors, depending on the mutual interconnection between the field and armature windings. They are separately excited, shunt excited, series excited, and compound excited.

Electric propulsion systems are one of the most important parts of any electric or hybrid vehicle. In fact these systems represent heart of electric and hybrid vehicles and they are consisting of electric motors, electric controllers and power converters. Electric motor is converting electric energy into mechanical energy. Mechanical energy is needed to propel the vehicle. Another part of electric motor is to enable regenerative breaking which considerably charge vehicle battery.

Electric controllers are giving control signals controlling the electric motor operation, producing required power and torque. Electronic controller is divided into these units

Sensor

Processor

Interface circuitry

Sensor is translating measured quantities like temperature, torque, voltage, speed, and flux into electric signals trough interface circuitry. All signals are imposed to some sort of conditioning before being submit to processor. Output signals from processor usually are amplified to the certain level enabling easier further use.
Power converter is unit supplying electric motor with proper voltage.
In order to define appropriate electric propulsion system for any electric and hybrid vehicle, there are a lot of factors needed to be specified. Maximum speed, acceleration, braking, climbing capability, range, vehicle weight and volume.

Electric motors with variable speed got usual characteristics. Those characteristics would be separated in low speed region and in high speed region. In the low speed region, electric motor has equal or constant torque. On the other hand, on high speed region electric motor got equal or constant power. In vehicle operations requiring low speed, voltage power supply to the electric motor is rising with speed increase.

Variable speed electric motor characteristics

Most basic electric vehicle performances are cruising speed (at its maximum), acceleration and grade ability. Maximum speed for electric vehicle is given by the maximum speed of the motor. It has to be clear that in normal conditions on the road, maximum capabilities are very rare in use. In most of the time while driving, power train got partial load. This load differs from road operating conditions. Uphill or downhill movement, acceleration, deceleration sudden braking and all other outside conditions are appearing with different ratio.

All these different conditions on the road are producing different energy consumption per distance unit. The unit of energy, in electric vehicles, usually is kilowatt hour (kWh). The power consumption per distance unit is kWh/km. That’s how energy consumption is evaluated. Power losses in motor drive and in transmission are known trough their efficiencies ?t and ?m

Back in time electric vehicles were mainly transformed from existing internal combustion motors vehicles, by changing conventional engine, fuel tank and some parts related with an electric motor, battery and controller. More or less all other parts were same for both vehicle constructions. It was resulting in some power characteristics degradation in new electric vehicle. Not to forget that fuel costs at that time were much smaller than today. Those 2 factors were some of the many factors resulting fading out of electric vehicle manufacturing and further development.

Looking today, modern electric vehicles are developed separately from scratch. Nowadays electric vehicles are based on original developed frame, body and design. With these changes, electric propulsion gets more flexibility and overall performance improvement. Concept of a modern electric vehicle drive is conceptualized with 3 main subsystems:

Electric motor with propulsion

Source of energy

Auxiliary

The electric vehicle motor propulsion contains vehicle controller, electronic converter of power, electric motor, transmission (mechanical) and driving wheels.

The source of energy comprises energy source, unit where energy management is provided, and unit or refueling (recharging).

The auxiliary subsystem consists of steering unit, climate control unit and auxiliary supply.

Depends of controlling inputs from accelerator and brake pedals, the vehicle control unit dispatch right control signals to the electric power converter. It regulates signals and power stream between energy source and electric motor. Power flow that goes backwards (regenerative braking) is restored to the energy source. Most types of batteries that are used nowadays got ability to accept regenerated energy.

The energy management unit communicates with controller, controlling regenerative braking and energy recuperation. Another task on this unit is control of recharging unit and direct usability of power source.

Auxiliary power supply gives power with different voltage levels for all electric vehicle auxiliaries. There are many different electric vehicle configurations. Electric propulsion may contain electric motor which power is connected or disconnected with the clutch. Gearbox is providing right gear ratios for speed power modifications. The differential, usually set of planetary gears, is a typical mechanical device enabling wheels from both sides of the vehicle to be driven with different speeds in case of curved road. Another combination of electric vehicle is when electric vehicle is equipped with multispeed gearbox reducing the clutch. This construction simplifies drive control (no gear shifting) and reduces weight and overall size of vehicle. Another development point in electric vehicles is replacing mechanical differential with two traction motors. In that way each motor propels one side wheel with different speed on a curved road. For further simplicity traction motors can be made- in wheel drive (traction motor placed inside wheel)
In any case one thing is for sure that electric motor has to have a high torque in order to accelerate vehicle up to needed level.

Cell and battery voltages

Batteries for electric vehicles got specification as 6V and 12 V. To produce this voltage cells inside batteries are connected in series so the voltage required to propel the vehicle is produced. Electric cells got their nominal voltage which represent approximate voltage when cell is in working condition (electrical power delivering). When power is given out, voltage will decrease and in charging conditions voltage will be rising. Electric charge is crucial parameter of a battery. To take SI units, SI unit is Coulomb. It represents a charge one Amp flowing per one second. This unit is practically small so in practice unit in use is Amp hour, meaning one Amp flowing per one hour. If we take battery with capacity of let’s say 20 Amp hours, it means that this battery can give 1 Amp for 20 hours or 2 Amp for 10 hours, or in practice 20 Amp for 1 hour. This is just theoretical point of view. Things are not that simple in practice, no matter what kind of battery is taking place.

It is very significant to understand that if one battery can provide 1 Amp for 20 hours and in case of 20 Amp drawn, it will be empty in less than one hour. Usual capacity of electric vehicles in use nowadays is given in 5 hour use or discharge. Capacity of the battery is greatly affected if stored energy (charge) is going more slowly or more quickly. There are lot unneeded inside reactions into cells. This reductive effect is most viewable at lead acid based batteries, but it is present in all types of batteries. Medium discharge will provide most effective using time for all batteries. That’s easy to say, but as we all know there is no ideal need for discharge. So theoretical and effective ”life” of battery is not the same. The better the battery is, the closer these values are.

As we know there are various sizes and types of electric vehicles. Electric means something running on electric charge or power. In all cases container for electric power needed to propel the vehicle are batteries. Batteries are main and key component in classic electric vehicles. It’s a vehicle component with highest volume, weight and cost of course. Hybrid vehicles also got batteries for a key element with great importance. Maybe their volume is smaller, but never the less main working principles are same.

When we are talking about battery we are imagining two or sometimes more electric cells which are joined together. Battery’s main business is converting one type of energy into another type. Chemical energy is converted into electrical. The cells inside batteries are made of electrodes, positive and negative, which is joined together trough electrolyte. Same chemical reaction among electrolytes and electrodes gives or generates electricity. That’s battery’s working cycle, when they are used to propel the vehicle. When batteries are in reverse operation that state is charging state, when battery is receiving electrical energy and converts into chemical energy.

Most known type of rechargeable battery are lead acid batteries. Although this battery concept was providing large number of combinations with materials and electrolytes forming a battery, only small set of combinations have been constructed and commercially developed for practical use in vehicles. Today, those batteries are based on lead acid, nickel cadmium, lithium polymer, nickel iron, lithium iron, sodium metal chloride, sodium sulphur. Other types of batteries recently developed and used are zinc - air and aluminum-air. They can be refueled mechanically. Yet, despite all various constructions of batteries and despite the 1,5 century development margin, still there is no battery developed and constructed quite suitable to use in electric vehicles. There are no wide suitable batteries for use in most electric vehicles. They all are custom made.
In these recently years there were some announcement of important and crucial development in production of suitable batteries, providing great moving span, fast recharge and smaller weight, size and cost. Taking those revolutionary achievements into consideration there is a great possibility of electric vehicle mass production.

Specific power, energy efficiency, energy density, amp hour efficiency, typical voltages, operating temperatures, discharge rates, life cycles are terms that needs to be explained so we could understand some of the problems related to battery production. There is some environment issues related with electric vehicles and with battery chemicals and process elements. Recycling of used batteries is very important issue which has to be resolved in order to prevent negative environment impact.

Ideas related with electric cars are slightly diverged into 6 available types of electric vehicles.

Electric vehicle based on traditional idea

Hybrid electric vehicle (combining battery and internal combustion engine)

Vehicles with replaceable fuel (vehicles using fuel cells or metal-air batteries)

Vehicles that are supplied with power lines

Vehicles using energy from the sun radiation

Vehicles storing the energy with super capacitors (nearly always hybrids having other source of power)

Human concerns about quality of live are rapidly growing in 20 century. Negative environment issues are resolving in many ways. Cars with eternal combustion motors seriously pollute urban areas. Emissions of toxic carbon monoxide and dioxide, noise and vibrations got negative impact on human’s quality of life. Many cities overcrowded with vehicles and polluted air are trying to do their best to avoid such negative impacts. Implementation of electric vehicles is one of the most serious cures to this situation. In favor of electric vehicles goes great technical and technological development in area of rechargeable batteries, electronic controllers and electric motors. Nowadays, many cities in the word got zero negative emissions tolerance in their centers. Only way to achieve that is encouraging implementation and further research in the area of electric vehicles. Recent improvements in batteries charging, improving of battery specific power, reducing battery specific weight, implementing of new materials are pushing idea of man relaying on electric vehicles. Nickel cadmium batteries can hold double the power of lead acid. Temperature high Sodium Nickel can hold tree times the power. This is great improvement, but it’s still not enough to provide bigger moving span to electric vehicles. Let’s make some assumptions. 45 liters or 10 gallons of petrol will give a vehicle moving range of 450 km or 300 miles. To take that distance electric vehicle will require 800 kg lithium battery. That’s great deal of weight, so further research and improvement of battery characteristics will deliver smaller and lighter batteries.

Start of the electric vehicles goes back in 1830’s. It’s very symptomatic, so many years passed by and there were no real revolution at everyday exploitation. Other vehicles, running on motors with internal combustion despite their negative impact to environment got their enormous success, making our modern life dependable upon various vehicles with internal combustion motors. They got great moving span and very easy refueling. On the other hand they produce such negative environment impact that got mankind to think how to reduce them.

First electric vehicles used elemental batteries non rechargeable, with considerable weight and dimensions. Mass production of rechargeable batteries leads to spreading use of electric vehicles back in 1900’s. Rare private cars and taxis were electric. Speed record was set at 106 km/h (66 m/h). These vehicles were staring instantly, quietly without any smell and other negative products.

Vehicles with internal combustion engines at that time were much more unreliable with need of manual cranking start. Also they were producing great deal of smoke, noise due to small thermal engine efficiency. Even with all those positive exploitation characteristics of electric vehicles, not to mention their environment friendly role, they lost development battle with their eternal combustion motor relatives.