Friday, May 22, 2009

Method and procedure for designing a Range extender EV from emission cycle standards

As new Cafe standards and and emission control standards are in place we need to improve the efficiency of the existing vehicles.

There are multiple approaches to address the issue:

  •  Improving existing ICE by use of new technologies and designs 
  •  Use of a supplement and increase the efficiency ( hybrids )
  •  Renewable non fossil energy ( EVs, fuel cells etc )

One of the problem people face on no fossil energy use  is the energy storage technologies are not affordable and the infrastructure is not ready and they are not proved. So we need an approach which is hybrid but more upgradable to future. As the Fuel cell and EVs depends on the electricity the approach needed to be electricity centric. 

One approach is a serial hybrid. There are other approaches like parallel hybrids, mild hybrids, strong hybrids, BAS hybrids etc. The good part of  serial hybrid is that its more future oriented and its a step closer to the renewable non fossil vehicles.

This post is an extension of the previous post of "something before volt".  This post is reflections of my thoughts on a 10 mile capable battery EREV. Because its for a 10 mile range, we assume the battery costs are less. We even  think it can be a ultra capacitor also because we need a device which can store and provide energy for the vehicle to travel 10 miles electrically.

The first step is a test EV ( electric vehicle ) which as capability to record the power used by the electric engine on a defined cycle. A cycle is a defined patten of driving for a particular time period. 

The Test  Ev will have the exact motor configuration we plan to have in our final product.
Example One motor 2 rear wheels ( say 90kw) and 2 in wheel motors ( 30kw ) for the 2 front wheels.

This configuration gives the advantages of rear wheel drive and on required conditions the front wheels can act and get AWD advantages. Secondly the front motors will  be more concentrating on regeneration of power from the regenerative breaking.

As a detailed step we will go through the different cycles defined by different standard authorities for the emission tests.

look at and get the required information , contact the  authorities and get the documents.

Some interesting cycles for US  are 

  1.  US06  : 600 seconds long  representation of aggressive, high speed and/or high acceleration driving behavior, rapid speed fluctuations, and driving behavior following start up.
  2.  FTP 75 :
  3. HWFET cycle :
  4. New york city cycle :
  5.  California Unified Cycle (UC) :
  6. The SC03 Supplemental Federal Test Procedure :

etc etc. for a primary study on different cycles use :

Similarly use all the countries you are interested in and get the cycle information. 

Now perform these cycles with the test EV and get all data points and plot graph on the power requirements against time , Now you have two graphs where one with speed vs time and second energy requirements vs time. 

Repeat the procedure with the cycles you have interest and make the data ready.

Now its time to choose a optimal electric generator with 
1) Emission characteristics matching the cycle requirement.
        2) Electricity generation capability which is at an optimal level for the above data collected cycles. Assume battery will be supplementing the extra power needs.

The modes the range extender will operate are :

  • PURE EV mode
  • Generator power only mode
  • Generator power + Battery power mode
  • Battery recharge mode
  • Generator power only run   and Battery recharge mode

Regeneration can occur on all the above mode as user uses the breaks and other regenerative mechanisms ( example: regenerative shock absorbers )

So as per the logic : The range extender will run on EV mode when the battery is full and above threshold range extender point. Lets say if its  10 mile battery 5 miles in EV mode
Once it reaches 5 miles, the generator kicks in and acts as primary source of running, Now the battery will act as a supplemental energy provider on acceleration, load and uphill ( more 
energy need scenarios ). The battery will be charged back when ever there is an opportunity for regeneration of the power. The generator will recharge the battery when the vehicle is 
in a stop position or need less power than the optimal point power which generator is deigned to generate.Once the power inside the battery reaches back to a level say "return EV mode point"
say 7 mile capability, the generator will be shut off back and the Range extender will run in a Pure EV mode. again when it hits back the threshold range extender point the generator will be kicking in again back.

The points 
 1) the constant generator capacity,
 2) Threshold range extender point
 3) Return EV mode point 

etc should be designed by the applications processing unit intelligence. This can be visualized as profiles ( example: city profile, High way profile, Up hill profile, AWD profile ,Intelligent AWD profile , etc will have different values for the points and will result in different drive experiences for the users). By adding plug in charging , the vehicle should be able to work as a plug in hybrid.

Once, the design of profiles are also completed, we will be almost ready will the design and only new places to explore may be the traction control mechanisms only. Once completing the data points and logic of control, we will be ready to develop the software needed and make out EREVs first tests. The data points can be perfected using software using proving grounds, test fleets 
etc and they can be always updated with software/firmware downloads.

Yes guys, We now did a design of a global focused designed EREV. Back to key points :

1) The Generator characteristics and control interface
2) The operating points
3) The traction control mechanisms to get max out of the electric motors
4) Electric motor characteristics
5) Power dissipation capabilities and storage capabilities of battery.

I think global vehicles can be born from more thinking than just dump executions.

© yankandpaste®

Saturday, May 9, 2009

Compressed air engines

Wondering this technology can be used as range extenders in EVs or PHEV or RE - EVs. One of the good points i see is no pollution at all. 

If these air engines offer constant RPM  and get the required power to generate the electricity then this will be one of the ground breaking technologies.  

The good part seems of PHEV/REEVs are:
1)  They can be charged over night for daily needs.
2)  For range anxiety needs the air compressed engines can be used.
3) On high speeds/Winds  using aerodynamic designs  the compressor can be re-filled.
4)  With small air compressor/ Old gas stations , we can refill the air with in minutes.

Some of the engine designs looks very good (i like the Engineair one ).

© yankandpaste®

Wednesday, May 6, 2009

Volt ? something before it ?

One of the problems we hear on GM Volt is its expensive, The component which makes it expensive is the battery.Is there a second way out ?

Again i started thinking and found a solution. Lets think of a below configuration

                  +--------------------------  Control  circuit
                  |                                                       |
Electric generator ------ Ultra capacitor----Electric Motor 

Why this is cost effective ?Genarator powers the electric motor,  The ultra capacitor stores the energy from the generator  some times ( like down hill, stops etc ) and other times it stores the regenerative energy . The electric motor takes electric energy from the ultra capacitor when it needs execss energy like up hill etc. This will be very cost effective as Ultra capacitr is not expensive as battery and range requiremnt is only 10 - 15 mile ( or even 5 mile )

If the Ultra capacitor can store energy for X miles AER, the Electric generator can always run in optimum capacity and be shut off till  the ultra capacitor reaches to be in a depletion area (say x-n ). Once its in depeltion area . the generator can charge and store more energy in it and support the power needs of the car by supplying additionl energy for uphill, merge etc. 

The down side : It wont perform on uphills like normal drive it the hill is very big/steep (after ultacapacitir runs out of energy ). 

 But comparing to the cost it should be a good step to consider before the volt and it will have less weight compared to BEVs and gives the cost effective first step on full electric drive. With the other idea listed ( the NP stroke engine and Active stroke mgmt ) this will be a 150 mpg cost effective vehicles.

This may be great config for a small car. intellectual property rights reserved for idea and implementation.

© yankandpaste®

NP Stroke engine and Active Stroke cycle management

Was thinking on how to increase the efficiency of an ICE engine. 

Searched on different engines  and got one idea.

We are not even using any heat energy generated by the internal combustion engine. Lets first explain a four stroke engine 

Four stoke engine consists of 
  Intake stroke
  Compression stroke
  Power stroke
  Exhaust stroke

In intake stroke, the air is taking in then compress the air ,fuel gets injected to the compressed air and then ignited results in the power stroke and after the compression stroke the exhaust gases will be removed in the exhaust stroke. Its all fine and give 35-37% efficiency.

One of the problem is the heat is never utilized for any purpose.  So the idea of six stroke engine came in.
The six-stroke engine is a type of internal combustion engine based on the four-stroke engine, but with additional complexity to make it more efficient and reduce emissions. 

Two different types of six-stroke engine have been developed since the 1990s:

In the first approach, the engine captures the heat lost from the four-stroke Otto cycle or Diesel cycle and uses it to power an additional power and exhaust stroke of the piston in the same cylinder. Designs use either steam or air as the working fluid for the additional power stroke. As well as extracting power, the additional  stroke cools the engine and removes the need for a cooling system, making the engine lighter and giving an estimated efficiency of 40%. The pistons in this type of six-stroke engine go up and down six times for each injection of fuel.

 There are two power strokes: one with fuel, the other with steam or air.

The second approach to the six-stroke engine uses a second opposed piston in each cylinder that moves at half the cyclical rate of the  main piston, thus giving six piston movements per cycle. Functionally, the second piston replaces the valve mechanism of a conventional  engine but also increases the compression ratio. 

I started thinking more in this direction and found another way called NP Stroke engine and Active Stroke cycle management for a better solution.. 

The theory i propose always gives variable  efficiency optimal according the  circumstance of operation.  

Lets go to the first proposal of NP  stroke engine. 

N is a number where this can be 1 to any number. P denotes Power stroke, Lets explain how NP stroke engine works when N is equal to 3.

The additional requirements/changes in the design is an additional  closed hot air chamber, Air injector , Heat transfer agent and injector ( ex water).

Once the 4 strokes of 4 stroke engine is over , the exhaust stroke will push the air to the air chamber. Once the exhaust stroke is over, instead of another intake stroke,  1/3rd of the hot exhaust air stored in the air chamber is released to the intake .After this a  compression stroke of this air occurs. Once its compressed, a heat transfer agent is injected (ex: water ). This agent will utilize the heat in the exhaust gas and convert to a vapour form results in a power stroke. Once the power stroke is over another exhaust stroke occurs and the exhaust is send out. Again in another intake stroke the air injector injects another 1/3 of the exhaust gas and same 4 strokes occurs. Lets call these strokes as thermal energy transfer strokes. Once the 4 strokes are over, the last 1/3 is utilized t make another 4 strokes. which results in total of 12 strokes.

Which means the engine gets 3 times efficient than the normal 4 stroke engine. 

Here a number of  questions arises : 

Is 3 an optimal number ? 
What happens in a cold place
What happens when i drive a lot
What happens when i start the car where engine is cool.

Here the second theory comes in effect. Active Stroke cycle management:

This consists of a temperature sensor, a decision making logic and a control to the air injector attached to the hot air chamber

The temperature sensor senses the temperature and decides the optimal number of heat exchange cycles which can be performed on the current temperature.

ex: In a cold condition starting , the engine can work as normal 4 stroke, while its running heat increases and it can increase the number of thermal cycles based on the   temperature and other deciding parameters.

So in a long ride, according to the temperature readings, it can control and decide N of the NP cycle engine.This will result in high efficiency engine which is according to the operating conditions

By the implementation its possible to have 120mpg engines using attaching proper thermal conversion cycles to a 40 mpg capable engine. Once its tuned to run ,  the efficiency will be increased heavily according to the operating conditions.

tail piece: This is to make sure this idea is fresh and intellectual property rights of this idea is for me as i didn't find anybody have the idea published. The intellectual property rights includes,idea,rights of implementations , decisions of different control parameters, heat transfer agent, agent recovery methods  etc and  the trade marks of  Active Stroke cycle management/ Active cycle management.

Thanks Wikepedia to understand the prior art for this idea.

© yankandpaste®

Sunday, May 3, 2009

Accelerator pedal for electric Car

DC Motor scenario

A simple DC controller connected to the batteries and the DC motor. 

If the driver floors the accelerator pedal, the controller delivers the full 96 volts from the batteries to the motor. 
If the driver take his/her foot off the accelerator, the controller delivers zero volts to the motor. 
For any setting in between, the controller "chops" the 96 volts thousands of times per second to create an average voltage somewhere between 0 and 96 volts.

The controller takes power from the batteries and delivers it to the motor. The accelerator pedal hooks to a pair of potentiometers (variable resistors), and
 these potentiometers provide the signal that tells the controller how much power it is supposed to deliver. 

The controller can deliver zero power (when the car is stopped), full power (when the driver floors the accelerator pedal), or any power level in between.

AC motor scenario

In an AC controller, the job is a little more complicated, but it is the same idea. The controller creates three pseudo-sine waves. It does this by taking the DC voltage from the batteries and pulsing it on and off. In an AC controller, there is the additional need to reverse the polarity of the voltage 60 times a second. Therefore, you actually need six sets of transistors in an AC controller, while you need only one set in a DC controller. In the AC controller, for each phase you need one set of transistors to pulse the voltage and another set to reverse the polarity. 

You replicate that three times for the three phases -- six total sets of transistors.

Saturday, May 2, 2009

Regenerative breaking

Regenerative breaking is used on hybrid gas/electric automobiles to recoup some of the energy lost during stopping. This energy is saved in a storage battery and used later to power the motor whenever the car is in electric mode.

Understanding how regenerative braking works may require a brief look at the system it replaces. Conventional braking systems use friction to counteract the forward momentum of a moving car. As the brake pads rub against the wheels (or a disc connected to the axle), excessive heat energy is also created. This heat energy dissipates into the air, wasting up to 30% of the car's generated power. Over time, this cycle of friction and wasted heat energy reduces the car's fuel efficiency. More energy from the engine is required to replace the energy lost by braking.

Regenerative braking utilizes the fact that an electric motor can also act as a generator. The vehicle's electric traction motor is operated as a generator during braking and its output is supplied to an electrical load. It is the transfer of energy to the load which provides the braking effect.

As the driver applies the brakes through a conventional pedal, the electric motors reverse direction. The torque created by this reversal counteracts the forward momentum and eventually stops the car.

At the most basic level, regenerative braking means re-capturing the kinetic energy of the vehicle's motion and turning it into another type of energy. Commonly, this is done by converting kinetic energy into electricity and recharging the car's battery with it.The energy captured in the battery is used moving the car later and due to the energy capture and reutilization the mpg for the car improves drastically.

© yankandpaste®

What is cD and why does it matter?

Aerodynamics. When discussing overall efficiency, sometimes it's easy to overlook just how important the shape of an automobile is in determining how fuel efficient it is

First, let's discuss what the term aerodynamics means. According to Merriam-Webster, aerodynamics is "a branch of dynamics that deals with the motion of air and other gaseous fluids and with the forces acting on bodies in motion relative to such fluids." Clear as mud? In this case, the fluid we're talking about is indeed air, and the easier it is for an object to cut through the air, the less energy is required to keep that body in motion.

For the purpose of comparing different automotive designs, engineers measure the resistance of a body to flow through the air using computational fluid dynamics simulations and wind tunnel testing. A flat board held perpendicular to the air flow may have a coefficient of 1 or more, depending on the shape of the edges and the surface texture. The drag coefficient is a unitless number and is based on the shape and surface properties of the object. Two identical objects that are different sizes will have the same cD. However, that doesn't mean they have the same overall drag. 

This, of course, is further complicated by the vagaries of the real world. The addition of items like outside mirrors, windshield wipers and radio antennas can cause a lot of disruption to air-flow. There is also the fact that cars often don't travel perpendicular to air-flow. Vehicles often encounter cross-winds when driving down the road so the airflow must be measured at various angles to ensure resistance is kept to a minimum. 

Safety is also a concern.The air-flow over a vehicle's body can trigger either lift or down-force just as it does with an aircraft wing. If a vehicle's shape causes too much lift, it can make the vehicle unstable and difficult to control. All of these factors must be balanced in the final design.

The designers of all of the most fuel efficient vehicles ever offered for sale have taken aerodynamics very seriously and as such, they all have a very favorable cD. For instance, the GM EV1 scored a cD of 0.195, which is quite good. For comparison, the 2010 Toyota Prius manages a fine 0.25 and the Aptera 2e (above) blows them both out of the water air with an amazingly low 0.15. When multiplied by the car's frontal area, the Aptera design scores even better due to its narrow, bullet-like shape with narrow out-rigger front wheels that are completely shrouded . For what it's worth, the brick-shaped HUMMER H2 scores a dismal 0.57 – further proof that its designers were in no way concerned with its fuel efficiency.

Besides the actual bodywork of an automobile, there are other factors contributing to the overall coefficient of drag any given car is able to register, including the car's tires and its ride height. Wide tires move more air and therefore take more power to move, and the air pressure of a given tire can have drastic consequences on its ability to roll. 

Why is all of this so important? Calculations reveal that about 60 percent of the energy used to move the average car goes towards overcoming its aerodynamic drag. That's huge, and means that even small improvements in a car's cD can pay big dividends in overall fuel efficiency.