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Hybrid Electric Vehicle (1999-2015)

Introduction

This page will focus on the hybrid electric vehicle (HEV) which has increased its popularity in recent years. Electric motor propulsion system is integrated into normal combustion engine vehicles in HEVs. This integrated motor contributes part of the propulsion force to the vehicle especially during climbing uphill and generates electricity by turning kinetic energy from braking to chemical energy in batteries pack. This technology improves the total vehicle power output and reduces fuel consumption. Another feature of the hybrid system is that the battery is charged by the power from the brakes and is recharged by converting energy from the combustion engine (motor–generator) when electricity is in low level inside batteries pack. Therefore, the vehicles technically do not require external battery charging. As the converting process is controlled by computer logic chips, complexity is being reduced. The vehicle reduces unnecessary energy loss (braking) and reuses energy, thus, the more efficient travelling. Air pollution is also reduced as a result of burning less fuel.

The whole control of the hybrid electric vehicle is the same as normal internal combustion engine vehicle. Unlike the pure-electric vehicle, the hybrid vehicle does not require recharging the battery in the specific charging station and have the same (or higher) travelling range as combustion engine vehicle. It does not have the inconvenience of short travel range and long waiting recharge time as the pure-electric vehicle. Moreover, it kept part of the advantages of the pure-electric vehicle, for example, more environmental-friendly and higher torque power (more responsive power transfer) compared to combustion engine vehicle.

The main market for this type of vehicle is private car user. It is due to the similar product pricing and the lower fuel consumption. It helps the private car user to reduce fuel cost while remaining the same vehicle performance.

Other private vehicle type

The previous vehicle before hybrid electric vehicle development is the normal combustion engine vehicle. Combustion engine vehicles are still having the largest market share as hybrid electric vehicle is considered as a relatively new technology which not many car manufacturers have the design of the hybrid electric vehicle. The limitations of the hybrid electric vehicle are that the vehicle has to integrate with a computer controlling system (software) and change the whole structure of power transfer system (hardware), which means that manufacturers have to redesign the whole vehicle which the assembling process is different. Nonetheless the overall amount of sale has increased as shown in Figure 1. This reflects that the public acceptance is increasing. The reason may be related to the sale price of the vehicle has decreased in recent years. At the early announce period, the technology was not well developed yet which the price of the vehicle was much higher, and the regenerative electricity system was not sufficient. After years of development, the system can now capture more brake energy and motor–generator is applied to recharge the battery directly from the combustion engine. Also, mass production has lowered the price of the vehicle. The first mass production hybrid-electric-vehicle is by the manufacturer Toyota since 1997. Other car manufacturers started to increase the production of HEV after 1997. The large variety of hybrid vehicle models provide car users more choices and the competition in the market encouraged manufacturers to enhance their design. After these years of improvement, the differences between combustion engine vehicle and hybrid vehicle have been reduced. Therefore, more car users started to consider buying HEVs.

Another competitive choice is the pure-electric vehicle. Through years of modification and introducing new technology, the battery of the pure-electric vehicle has increased the energy density, which consequently increased the range of the vehicle and input voltage. Shorter recharge time and longer range bring pure-electric vehicle into practical use. In recent years, Tesla designed a pure-electric vehicle which is compatible with combustion engine vehicles in terms of range and performance. Pure electric vehicle is sometimes considered as the next future generation of the automobile due to its clear (no air pollution directly released) and advanced computer monitoring system. However, it is expected that pure-electric vehicle cannot completely replace neither combustion engine vehicle nor hybrid electric vehicle because of the limitation of the recharge time. Instead, HEV can in fact be benefited by this improvement from the pure-electric vehicle by the electric component parts. It can help further improve the hybrid vehicle electric use and decrease the fuel consumption.

In spite of the pure-electric vehicle, the similar featured vehicle named plug-in-hybrid-electric vehicle has also been announced which consists all the functions from the HEV with the external charging plug. This type of vehicle allows users to charge the vehicle from a power adapter. This vehicle contains all the characteristics from both pure-electric vehicle and combustion engine vehicle. Furthermore, the external charging methods can sufficiently reduce the fuel consumption as the vehicle has another charging methods when the battery is in low electricity level. It is known that the electricity is considerably cheaper than gasoline, and users do not have to burn fuel just for recharging the battery. The process is exactly the same as the pure-electric vehicle with just a slightly smaller battery pack. This new type of vehicle is also challenging the market of the hybrid electric vehicle.

Invention of technology of HEV

First of all, the re-generation of electricity from braking is a new invention by experts. This is a new approach specifically designed for electric vehicle since traditional combustion engine vehicles do not have the battery parts. The experts designed a system (AMC developed in 1967) that captures the conversion of kinetic energy to electric energy during deceleration and convert it into chemical energy in battery storage. For conventional vehicles, the kinetic energy will turn to heat and sound energy from brake callipers which wasted the energy. The vehicle is highly dependent as the vehicles require a storage of these collected energy, electric vehicle is the ideal vehicle type for installing such system.

The next important part is the integration of electric motor to the existing power transfer structure. The expert combined the normal combustion engine used in conventional vehicle and applied new electric motor power to the drivetrain. Due to the special power transfer moment (mostly during uphill), the electric motor is not constantly contributing to the system. It required experts to develop an arrangement connection to combine two power sources together. After the development of the combined power, the vehicles nowadays have a smooth timing for the system to connect two powers together by the improvement of the drivetrain parts and the automatic decision making by the computer monitoring system.

The motor generator is another invention just for the hybrid vehicle. It is a technology existed for a long time which is essentially using a rotating energy source to recharge the batteries pack. Experts brought this technology into the hybrid vehicles which helped the vehicles recharge the batteries when they are on but not using the combustion engine. However, for this technology, the vehicles kept burning fuel but the energy is wasted. Experts spotted this waste of energy and came up with the idea of having a system to collect the wasted energy. This motor generator is not a new technology but is merged and modified to fit the hybrid vehicle. This effectively helps the vehicles reduce the fuel waste and avoid low electricity level in the batteries.

Early market development

The very first starting prototype was built in the 1960s by Victor Wouk who designed the hybrid drivetrain which can receive power from both combustion energy and electric motor. At that stage, the prototype is not efficient as the electricity is consumed quickly. However, this idea started to raise the scientists’ attention. In the 1980s, David Arthurs came up with the idea of collecting energy from braking. After the development of generating energy from deceleration, the biggest problem of electricity shortage in the earlier stage is moderately solved. It is clearly shown that the functional enhancement of the electricity source acted as an important role in the 1960s design.

The first mass production hybrid electric vehicle started from 1997 by a Japanese manufacturer called Toyota . The targeted buyers were the mid-class users. The aim of the hybrid electric vehicle is to create a new type of vehicle which is considerably more environmental-friendly. Due to the mass production, the production of the vehicle highly increased, and the sale price decreased. It also improved the product quality as the machines in manufacturing produced uniform quality parts. Mass production can shorten production time so as to supply for the increasing demand in the market. Despite the mass production, different companies joined the hybrid electric vehicle market and this created a high competitive environment in the hybrid vehicle industry. Competitive market encourages companies to invent new technology or improve the existing products. Theoretically, the user can be benefited the most because of product enhancement. Moreover, more companies entering the industry will usually result in price drop. Honda joined the hybrid vehicle market and stopped Toyota’s monopoly. This brought buyers more vehicle choice.

The hybrid electric vehicle is a new type of vehicle that provides a relatively environmental-friendly transportation method, the total power output of the vehicle has been increased too.

Policy in the birthing phase

As the hybrid electric vehicle is the improvement of the conventional vehicle design. All the current policies for internal-combustion-engine vehicles have been adopted. All the vehicle requirements are the same as the combustion-engine vehicles including the safety impact check. It is because the hybrid vehicles have the same engine design and the control is the same. The only new policy is the safety check of the new type of drivetrain and the new standard requirement for electric system.

Meanwhile, attempts were made by some countries promote hybrid vehicle to the public by introducing tax reduction (eco-tax credit). It is aimed to attract buyers to choose hybrid vehicles through offering cheaper price. It is proved to be effective in encouraging buyers to choose hybrid vehicles. The procedure is different between countries but the general way is to reduce the tax charged during the vehicle registration. In some countries, the amount of reduction depends on the number of vehicles registered, so the earlier purchasers can be offered higher tax reduction. Contrarily, some countries offer equal reduction.

Growth of HEV

From Figure 1, it is clearly shown that the sales of the hybrid electric vehicle was increasing. It can be referred to the concept of S-curve which appeared in most of the transport mode. S-curve splits the growth of technology into 3 main stages – birth, growth and maturity. The birthing stage of the technology will appear in an exponentially increasing status. The increment along time will rapidly increase. The growth stage is after the exponential increase in volume, the increment starts to uniform and the population of the new technology is appeared to have steady pace of increase. This stage usually takes a longer time compared to the birthing stage. At last, the technology starts to become mature which the volume tends to hold at a steady amount. The total volume will not have significant increase. Only if new revolutionary improvement is announced, these improvements will increase the volume and brings the curve back into growth stage. Another possibility is that change will happen when a new alternative is developed and is proved to better fulfill the social needs. In the case of hybrid electric vehicles, the sale increment seemed to turn stable after 2006. There is one obvious drop between 2007 to 2011. The drop may be caused by some external event (another mode) or internal event (hybrid vehicle itself).

Firstly, as mentioned, the private sector like the manufacturers have joined the hybrid vehicle industry which increased the production and the wider range of available models. This competitive situation affected the sale price and the quality of the vehicle. This is the start of the hybrid vehicle industry, it successfully attracted the buyers’ attention thus led to rapid growth since 2006. This stage can be considered as the birthing stage. After 2006, the demand for hybrid vehicle seemed to grow more steadily. The improvement in every new generation of the hybrid vehicle will increase the growth slightly.

Additionally, public sector like governments have contributed to the growth, the tax reduction system attracted buyers to purchase the hybrid vehicle.

The reason for the obvious drop between 2007 to 2011 is an external event. Considering the timeline and global issues, the drop matches the time of the global financial crisis. At that time, the global economic status dropped significantly, and people were less likely to purchase a vehicle. Along with the recovery of the financial system, the sales of the hybrid vehicle returned. Another drop started in 2014 was due to the drop in gasoline prices in the U.S. This external factor influenced buyers to use combustion engine vehicle for its lower fuel cost. As the biggest advantage of hybrid vehicles is the lower fuel consumption, the drop of gasoline has weakened this advantage. Hence, the sales of HEVs has decreased since 2014.

Mature phase of HEV

Describe attempts to adapt the mode changing markets, competitive conditions, and policy values. Describe how "lock-in" has constrained these adaptations. Identify any opportunities you see to "re-invent" the mode so that it can better serve the needs of today and tomorrow.

Mature phase refers to the when the market demand reaches the peak and is saturated. Generally, the volume of the mode is steady which the increment of the volume is limited. In order to break this phase, new improvement is required to boost the sale of the vehicles. This improvement needs to pose substantial positive impact on the vehicle design. Take the early age of hybrid vehicle industry as an example, the re-generation electricity system from brakes was recognised as a revolutionary design which boosted the sale of the hybrid vehicles.

In fact, the hybrid vehicles represent a product that can fit into the changing market. HEVs are comprised of two opposite types of power mechanisms, hence, they keep both the internal combustion engine and the characteristic of the pure electric vehicles. In other words, HEVs contain the pros and resolve the major cons from both sides. For instance, they are more environmental-friendly and have faster acceleration which are the strengths of the pure-electric vehicle, while do not have the problems of short travel range and long recharge time. Furthermore, performance of HEVs is improving. Under the competitive condition, the manufacturer keep improving the vehicle design like better aerodynamic shape to reduce fuel consumption and increase the speed.

However, the internal combustion engine vehicles have “locked-in” to people’s daily life. In general, a large number of people still have the perception that combustion engine can provide more torque power and is more reliable. Many think that the slightly higher price of hybrid vehicle does not worth the extra charge as the effectiveness of the hybrid system is limited.

The increasing popularity of hybrid vehicles is changing the conventional car industry. They cut the market share and reduced the conventional car sale. However, hybrid electric vehicles have another similar alternative to compete with. The new pure-electric vehicles have been proved to have hugely increased the travel range of one recharge. In addition, pure-electric vehicles generally have faster acceleration response and produce less pollution.

In order to be competitive with the improving pure-electric vehicles, hybrid electric vehicles need to show the advantages over the pure-electric vehicle and improve its existing features. The noticeable features of the current pure-electric vehicles are the charging time and the shorter range. The charging time of hybrid electric vehicles is much shorter (Tesla 30 minutes for 80% charge of the battery in the specific charging station compared to 5 minutes fill up full tank of fuel for hybrid). Therefore, re-fuelling is not the prioritised concern in this case as hybrid electric vehicles have dominance in terms of charging time. On the other hand, pure-electric vehicles keep increasing the travel distance per charge. So, to enhance their competitiveness, it is essential for hybrid electric vehicles to improve their travel range which can be achieved by eliminating fuel consumption.

Basic Equation

Life-cycle of the HEV can be estimated by regression of S-curve.

Equation 1

K value estimation

Table 1

Equation 1

Assumed K value is 500000 and Equation 1 will produce the y value. These y value and respective year value can form a linear trendline line. The trendline will have the y-interception and the slope (b). Furthermore, the R-square value can be obtained by calculating the errors from trendline to the y value. And the same procedure performed by increasing K value by 10000. Comparing the R-square individually and the K value from the highest respective R-square value should be chosen. This is the brief K value obtained by comparing the linear response.

Constant estimation

Table 2
K	500903
b	0.76693943
t0	2005.9386

The Table 2 K value is first briefly obtained in Table 1 and further modified to obtain the smallest R-square value. K is estimated as 500903 which is considered as a fully saturated level. b is a constant which governing the shape of the S-curve, which the smaller value will result in a flatter curve. t₀ is the year that achieving half of the K value. Combine these three variables into Equation 1. It can produce the estimating value of the sale volume by given year.

Estimation and Plotting

Equation 2

	Table 3
Year	Raw sales number	Estimation
1999	17.00	2435.26
2000	9350.00	5214.29
2001	20282.00	11094.05
2002	36035.00	23292.44
2003	47600.00	47600.02
2004	84199.00	92368.68
2005	209711.00	164008.85
2006	252636.00	256347.47
2007	352274.00	347109.72
2008	312386.00	415420.01
2009	290271.00	457208.44
2010	274210.00	479615.46
2011	268807.00	490786.28
2012	434344.00	496153.26
2013	495534.00	498685.98
2014	443823.00	499871.07
2015	384404.00	500423.38
Intercept	-61923664.64	-80472159.98
Slope	30968.61520	40236.06654
R-squared	0.87092	0.91241
P-value		0.44097

Above table is the estimated sale volume and the raw sale volume data. Where the p value calculate by assuming 2 tails and assuming two set of data have unequal variance (heteroscedastic).

Figure 1

Figure 1 shown estimated regression line with the variable calculated in Table 3. It is shown that the regression line generally overlapped with the actual data. There is two main difference as the sale volume dropped start from 2008 to 2011. Historically, the drop seems like caused by the global financial crisis. And at that time, the willingness of people to purchase a new vehicle is decreased. Apart from 2008 to 2011, the sale volume also dropped from 2014. It is caused by an external factor – the price of gasoline dropped since 2014 in the US which highly affecting the sale in the electric vehicle market. However, the regression line is not considering the dropped value due to external factor especially global financial crisis drop. This accident is not contributing to the natural cycle of the transportation. It is expected the sale reached the peak at 2013 where sale volume is about 500000. The market stops growing as the more advanced or beneficial vehicle type announced like the plug-in-hybrid-electric vehicle (PHEV) and the pure-electric vehicle. The PHEV started to replace the HEV as the external charging ability. Unless the HEV have the new revolutionary improvement, transport life cycle theory suggested the sale volume will go steady throughout the mature phase and decrease the volume due to another innovation vehicle started to replace HEV. It is also expected the sale volume move into mature stage after 2010. Which shown in Figure 1 plotting of the regression line.

With R^2=0.91241 This R-squared value (0.91241) is close to 1 which implied the regression equation used above is generally well-fit the data obtained. The estimated s-curve is well-presenting the actual sale data. However, due to the limited data size, the raw data curve is not clear about the turning of maturity, so the accuracy about the saturation status level is uncertain. But it is assumed the maturity is about the same level as estimated due to the newer PHEV and pure-electric vehicle announced which expected to decrease the sale of HEV.

Other statistic result

table 4

table 5

table 6

3 table above showed the statistic result in this regression model.