help me in design calculation for hybrid car - DIY Electric Car Forums

# DIY Electric Car Forums> EV Conversions and Builds> Technical Discussion

 NuWiki Register Blogs FAQ Members List Social Groups Calendar Search Today's Posts Mark Forums Read

#1
08-06-2012, 10:15 PM
 chipsmore29 Junior Member Join Date: Aug 2012 Posts: 4
help me in design calculation for hybrid car

Hye everyone....
My project is regarding with hybrid car.can someone show me the calculation and the formula used to proved this value.taking example honda insight:

for engine:

Engine Type: In-Line 4-Cylinder
Displacement (cc): 1339
Horsepower @ rpm (Combined: engine (SAE net) + electric motor): 98 @ 5800
Torque (lb-ft @ rpm, combined engine (SAE net) + electric motor): 123 @ 1000-1700
Bore and Stroke (mm): 73 x 80
Compression Ratio: 10.8 : 1
Valve Train: 8-Valve SOHC i-VTEC®

how do they get the horsepower and torque?what is the formula used?

for electric motor (BLDC motor):

Power (hp @ rpm): 13 @ 1500
Torque (lb-ft @ rpm): 58 @ 1000

how do they get the horsepower and torque?what is the formula used?

battery specs:

Output (Volts): 100.8
Rated Capacity: 5.75 Ah

#2
08-07-2012, 02:23 AM
 PStechPaul Senior Member Join Date: May 2012 Location: Cockeysville, MD 21030 Posts: 2,939
Re: help me in design calculation for hybrid car

The basic equations are:
T(lbft)=HP*5252/RPM

HP=T(lbft)*RPM/5252
So 13HP at 1500 RPM is 45.5 lbft

58 lbft at 1000 RPM is 11HP

These are probably the peak values. Usually an electric motor has a fairly flat torque curve up to maximum RPM and the HP is linear up to that point and then levels off or drops.
#3
08-07-2012, 02:57 AM
 chipsmore29 Junior Member Join Date: Aug 2012 Posts: 4
Re: help me in design calculation for hybrid car

thanks for the reply....but what i mean is how they calculate the value?for example,for motor,stated that power is 13hp at 1500rpm.how do they get the value 13hp at 1500rpm?is there any other value or parameter or other formula before to get it?the formula that i know is like P=IV or P=Tw or T=Fr....correct me if im wrong....

#4
08-07-2012, 03:45 AM
 PStechPaul Senior Member Join Date: May 2012 Location: Cockeysville, MD 21030 Posts: 2,939
Re: help me in design calculation for hybrid car

For an electric motor you can get the power from the equation:
P = E * PF * V * I
Where E is efficiency and P is power factor. V is voltage and I is current.

The E and PF are nameplate data determined by design and testing.

If you really need to determine the actual power or torque you need to do a dynamometer test. You can connect a generator to the output shaft and add a resistive load to get the approximate power (if you know the generator efficiency). And you can determine torque by mounting the motor on a set of bearings or rollers and then adding a torque arm and a scale, so a 2 foot arm reading 50 pounds will be 100 lbft torque.
#5
08-07-2012, 06:38 PM
 chipsmore29 Junior Member Join Date: Aug 2012 Posts: 4
Re: help me in design calculation for hybrid car

thanks PStechPaul....im looking for a formula that will give me the hp and torque numbers based on the input....can someone show me the calculation/formula/other factor needed for this?just use the example given above and justify it....can show me the flow of calculation and formula needed including efficiency etc....thanks in advance
#6
08-08-2012, 07:44 AM
 TigerNut Senior Member Join Date: Dec 2009 Location: Calgary Posts: 277
Re: help me in design calculation for hybrid car

Quote:
 Originally Posted by chipsmore29 thanks PStechPaul....im looking for a formula that will give me the hp and torque numbers based on the input....can someone show me the calculation/formula/other factor needed for this?just use the example given above and justify it....can show me the flow of calculation and formula needed including efficiency etc....thanks in advance
For an internal combustion engine, there is no simple formula that gives you power and torque based on number of cylinders, displacement, bore/stroke, etcetera. The power and torque curve (not just single values), as a function of RPM, depend on those parameters, but also the cylinder head design, valve size and number, port shape and volume, the camshaft profile, and a bunch of other things. When a manufacturer quotes a power and torque number, this is typically based on actual power and torque measurements that were made on a dynamometer.

Similarly, the power output of an electric motor depend on a great number of design parameters, not just the voltage and current. The torque and speed capabilities of a motor depend on the number of magnetic poles and the number of turns of wire in the poles and armature... and then the power handling depends on the resistance of those wires and the overall size of the motor. You couldn't expect a small motor to put out so much torque that it would twist its output shaft in half.

It sounds like you need to first obtain some grounding in algebra and physics; then do some research on basics of electric motors and internal combustion engines; and THEN you will have a better understanding of how to apply the information Paul tried to give you.
#7
08-08-2012, 09:43 AM
 chipsmore29 Junior Member Join Date: Aug 2012 Posts: 4
Re: help me in design calculation for hybrid car

Quote:
 Originally Posted by TigerNut For an internal combustion engine, there is no simple formula that gives you power and torque based on number of cylinders, displacement, bore/stroke, etcetera. The power and torque curve (not just single values), as a function of RPM, depend on those parameters, but also the cylinder head design, valve size and number, port shape and volume, the camshaft profile, and a bunch of other things. When a manufacturer quotes a power and torque number, this is typically based on actual power and torque measurements that were made on a dynamometer. Similarly, the power output of an electric motor depend on a great number of design parameters, not just the voltage and current. The torque and speed capabilities of a motor depend on the number of magnetic poles and the number of turns of wire in the poles and armature... and then the power handling depends on the resistance of those wires and the overall size of the motor. You couldn't expect a small motor to put out so much torque that it would twist its output shaft in half. It sounds like you need to first obtain some grounding in algebra and physics; then do some research on basics of electric motors and internal combustion engines; and THEN you will have a better understanding of how to apply the information Paul tried to give you.
oic....it seems like i need to study a lot of things to do this project.i just know a little bit of formula which is the general formula of speed,torque,etc....mmmm....i cant find any source from book or internet the complete sample calculation for ice design as well as motor design.do you have any source or sample calculation for these design?can u tell me what is the exact parameter/value/any related things and the formula needed in order to design ice and motor(BLDC)?my mind is really mixed up with a lot of formula and i dont know which formula that i should use....really appreciate ur help...
#8
08-08-2012, 09:50 AM
 major Senior Member Join Date: Apr 2008 Location: Ohio, USA Posts: 7,330
Re: help me in design calculation for hybrid car

Quote:
 Originally Posted by chipsmore29 i cant find any source from book or internet the complete sample calculation for ice design as well as motor design.do you have any source or sample calculation for these design?can u tell me what is the exact parameter/value/any related things and the formula needed in order to design ice and motor(BLDC)?
This normally requires an engineering degree and about 10 years of experience in the field to comprehend for each the ICE and EM.
#9
08-08-2012, 11:56 AM
 TigerNut Senior Member Join Date: Dec 2009 Location: Calgary Posts: 277
Re: help me in design calculation for hybrid car

Quote:
 Originally Posted by chipsmore29 oic....it seems like i need to study a lot of things to do this project.i just know a little bit of formula which is the general formula of speed,torque,etc....mmmm....i cant find any source from book or internet the complete sample calculation for ice design as well as motor design.do you have any source or sample calculation for these design?can u tell me what is the exact parameter/value/any related things and the formula needed in order to design ice and motor(BLDC)?my mind is really mixed up with a lot of formula and i dont know which formula that i should use....really appreciate ur help...
A core principle for an electric motor's operation is the Lorentz Force equation: http://en.wikipedia.org/wiki/Lorentz_force. Page down to where they talk about force on a current-carrying wire. Pretty much everything else about electric motor design is geometry and mechanics of materials.

For an internal combustion engine, the principal objective is to burn gasoline in the cylinders at or near the stoichiometric air/fuel ratio, so that the expanding gas can force the pistons to do work via the connecting rods acting on the crankshaft. The more fuel/air mixture you can burn in a given amount of time (i.e. the higher the cylinder pressure, RPM, and/or displacement), the more power you can make. Everything else is fluid dynamics and mechanics of materials.

That's a pretty glib overview, and intentionally so, but as we've been saying: There is no single, simple formula for motor or internal combustion engine design. First of all, you will need really good applied math background including algebra, geometry and calculus. Secondly, you need to understand the chemistry and physics principles involved; third, as Major says, at least a decade working full-time on engines and/or motors, before you can confidently take a motor or engine design and predict its performance purely based on the internal parameters.
#10
08-08-2012, 01:03 PM
 PStechPaul Senior Member Join Date: May 2012 Location: Cockeysville, MD 21030 Posts: 2,939
Re: help me in design calculation for hybrid car

IMHO the OP is too much concerned about details that are not really directly relevant to a DIY hybrid or EV. A hobbyist with a basic knowledge of physics and electrical principles can design and build an EV with guidance from people with experience on this forum, and from the many books and websites about DIY projects and commercial EV and hybrid design. The DIY resources pretty much provide a step-by-step process to accomplish the goal of using electric power for vehicular propulsion, or for simply augmenting it as a hybrid.

If the goal is designing a hybrid vehicle from the ground up, then it requires an advanced college level understanding of many disciplines, as well as practical experience in design engineering. I would dare say that all commercial hybrids and EVs were developed over several years of intense effort by a team of engineers, technicians, mechanics, and businessmen.

 Share or Bookmark this

 Thread Tools Display Modes Linear Mode

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is Off Forum Rules
 Forum Jump User Control Panel Private Messages Subscriptions Who's Online Search Forums Forums Home General Forum     EV News     DiY Electric Car Forum Help Desk     Chit Chat EV Conversions and Builds     All EV Conversions and Builds     Technical Discussion     Batteries and Charging     Controllers     Electric Motors     EV Performance     Electric Bikes     Non Road Going Vehicles DIY EV Wiki     EV Information     DIY Wiki Discussion Production EVs and Hybrids     Production EVs     Production Hybrids Marketplace     Classifieds     eBay EV-Related Auctions     Parts Vendors     Professional Conversion Services     EV Dealers EV Clubs     Dallas EV Club     TexomaEV.com     EVAoSD     NEAA     NZEVA     B-EVA     UtahEVInterest External Information     EVDL List Vendors     Vendor Deals

Support DIY Electric Car