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electric supercharger 7
- Thread starter ed911
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GregLocock
Automotive
The 200V battery is used for regen. The bus voltage of the low voltage circuit is irrelevant.
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Greg Locock
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Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
Fabrico, the whole point of this thread is to discuss electric supercharging, and to my way of thinking that includes comparing it to normal direct mechanically driven superchargers.
An air bypass system is used in order to obtain far lower parasitic drive losses when boost is not required. That is a very important point in the the whole comparison between electric drive, and direct mechanical drive. It eliminates the single biggest disadvantage of direct mechanical drive.
My whole point raising all this, is that a properly controlled mechanically driven positive displacement supercharger would be extremely difficult to beat when all aspects are taken into consideration.
Throttle response, or lack of the dreaded lag is another aspect of electric supercharging. Power to the electric drive motor will need to be very accurately modulated, with PWM, many Kw of it. Nobody here has mentioned that little problem so far. You cannot just switch it on and off. Location of the throttle is also very important for throttle response. Downstream is always better. Incidentally Toyota use a downstream throttle with a roots blower, so it is relevant to understanding what is already out there.
Lastly, by far, the majority of air bypass systems used today use the ECU to fully map the bypass valve electronically. When I built my bypass it was totally pneumatic. Toyota also use full pneumatic control, but they are still the only OEM to do so.
I only mentioned it because to anyone deeply interested in supercharging it is a very simple and practical alternative to software mapping. The adaption of an ordinary external wastegate to do the job is a very effective solution, which is my only contribution.
Electric supercharging has a very big job ahead of it to beat direct mechanical drive, and there is a lot more to it than just hooking up a very powerful electric motor to a centrifugal compressor and calling the job done.
An air bypass system is used in order to obtain far lower parasitic drive losses when boost is not required. That is a very important point in the the whole comparison between electric drive, and direct mechanical drive. It eliminates the single biggest disadvantage of direct mechanical drive.
My whole point raising all this, is that a properly controlled mechanically driven positive displacement supercharger would be extremely difficult to beat when all aspects are taken into consideration.
Throttle response, or lack of the dreaded lag is another aspect of electric supercharging. Power to the electric drive motor will need to be very accurately modulated, with PWM, many Kw of it. Nobody here has mentioned that little problem so far. You cannot just switch it on and off. Location of the throttle is also very important for throttle response. Downstream is always better. Incidentally Toyota use a downstream throttle with a roots blower, so it is relevant to understanding what is already out there.
Lastly, by far, the majority of air bypass systems used today use the ECU to fully map the bypass valve electronically. When I built my bypass it was totally pneumatic. Toyota also use full pneumatic control, but they are still the only OEM to do so.
I only mentioned it because to anyone deeply interested in supercharging it is a very simple and practical alternative to software mapping. The adaption of an ordinary external wastegate to do the job is a very effective solution, which is my only contribution.
Electric supercharging has a very big job ahead of it to beat direct mechanical drive, and there is a lot more to it than just hooking up a very powerful electric motor to a centrifugal compressor and calling the job done.
patprimmer
New member
Come on guys play nice.
This thread contains a lot of VERY interesting stuff, and at least probes into new developments and I for one do not want to see it disappear because of inappropriate argument.
Questioning where problems might lay, or where one seems to be intently following one path to the extent of becoming blind to other possibilities is healthy, but arguing the point to save face when evidence is presented to question your previous comments is pointless and damaging to creative thought.
Warpspeed
Did you read my post of 20/06/06
I appreciate it was a bit brief, but believe it implied these areas might contain problems still to be overcome, or to at least beg the question.
I was sure many people here with special knowledge in some aspects would each add their 2 cents worth.
Passion can be good, but it should not overpower reason.
Regards
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
This thread contains a lot of VERY interesting stuff, and at least probes into new developments and I for one do not want to see it disappear because of inappropriate argument.
Questioning where problems might lay, or where one seems to be intently following one path to the extent of becoming blind to other possibilities is healthy, but arguing the point to save face when evidence is presented to question your previous comments is pointless and damaging to creative thought.
Warpspeed
Did you read my post of 20/06/06
I appreciate it was a bit brief, but believe it implied these areas might contain problems still to be overcome, or to at least beg the question.
I was sure many people here with special knowledge in some aspects would each add their 2 cents worth.
Passion can be good, but it should not overpower reason.
Regards
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
globi5
Mechanical
- Oct 10, 2005
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Additional papers on electrically assisted supercharging:
I believe, the reason we don't see them in cars yet is less technically based but rather because of the higher costs of a supercharged engine (electric or not) in general and these extra costs simply don't justify a supercharger in the first place even if fuel consumption is reduced by 15% due to the higher efficiency at cruising. A 1.2l engine with supercharger is still more expensive than a 1.6l n.a. engine.
I believe, the reason we don't see them in cars yet is less technically based but rather because of the higher costs of a supercharged engine (electric or not) in general and these extra costs simply don't justify a supercharger in the first place even if fuel consumption is reduced by 15% due to the higher efficiency at cruising. A 1.2l engine with supercharger is still more expensive than a 1.6l n.a. engine.
Well said, patprimmer.
Although some regulation of the electric motor would likely be needed to control air flow, it would seem that perhaps half that function could be done working with the air itself. Of course another viable alternative is to have more than one air pump.;-)
As far as electrical demands and my very limited experience, most of the testing was done on a 426 cubic inch 2-stroke engine AND the entire system was 12 volt! It does not get much worse than that, yet it was close to being pratical for an on-demand duty cycle. Using higher voltage DC, 3-phase AC, capacitors, or a combination of these, would be nothing but better.
It may or may not be considered parasistic, but the power required to spool up an electric blower for on-demand type system is substantial, almost colasal. This might be a good place for capacitors. Though lag and amperage are one, there is no question that electric motors can spool up fast enough. A well thought out system would not have to be expensive.
patprimmer
New member
I would consider the power used to charge up batteries or capacitors to be parasitic, unless they are produced entirely from required braking. This seems unlikely to me.
I would think there might be a substantial difference in the spool up time for the unloaded motor vs the spool up time to full boost.
0.4 seconds can be quite a long time when waiting for throttle response in a sporty car. Probably quite OK in a truck, limo, aircraft or most boats.
Regards
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I would think there might be a substantial difference in the spool up time for the unloaded motor vs the spool up time to full boost.
0.4 seconds can be quite a long time when waiting for throttle response in a sporty car. Probably quite OK in a truck, limo, aircraft or most boats.
Regards
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
Pat, now that you mention it, I have put my electronic engineers hat on, and been giving this some serious thought from the control aspect. I see the control of an independent electric assist of a turbo as being rather problematic, quite apart from everything else.
For a start, there will be a reasonably complex (approximately) square law relationship between the boost produced and motor Rpm of the assisting compressor, and meanwhile the turbo is spooling up all by itself fairly independently of anything else with it's own dynamics.
That rush of acceleration common to turbo engines may become difficult to control, because as the turbo spools up, the assisting booster compressor must somehow be smoothly reduced in effect.
My only experience is with positive displacement (roots blower) turbo assist, and that has none of the flow control problems, because of the fixed displacement and solid mechanical coupling to the engine.
I believe inertia, and the grossly nonlinear characteristics and response of a centrifugal electric booster my be extremely difficult if not impossible to control satisfactorily in any feedback loop. The sort of fast stable response that will be required may just not be possible.
I am fairly sure a proper feed forward control system is the only way it could be made to work at all.
While a nice rush of acceleration might feel pretty good, something where boost pressure fluctuates up and down unpredictably, with two systems fighting each other, might feel rather odd. When the centrifugal booster backs off, exhaust gas volume falls...
I believe a feed forward system, (possibly modified with some self learning ability) may work, but the control system, and all the required sensors to do it would significantly add to cost and complexity.
For a start, there will be a reasonably complex (approximately) square law relationship between the boost produced and motor Rpm of the assisting compressor, and meanwhile the turbo is spooling up all by itself fairly independently of anything else with it's own dynamics.
That rush of acceleration common to turbo engines may become difficult to control, because as the turbo spools up, the assisting booster compressor must somehow be smoothly reduced in effect.
My only experience is with positive displacement (roots blower) turbo assist, and that has none of the flow control problems, because of the fixed displacement and solid mechanical coupling to the engine.
I believe inertia, and the grossly nonlinear characteristics and response of a centrifugal electric booster my be extremely difficult if not impossible to control satisfactorily in any feedback loop. The sort of fast stable response that will be required may just not be possible.
I am fairly sure a proper feed forward control system is the only way it could be made to work at all.
While a nice rush of acceleration might feel pretty good, something where boost pressure fluctuates up and down unpredictably, with two systems fighting each other, might feel rather odd. When the centrifugal booster backs off, exhaust gas volume falls...
I believe a feed forward system, (possibly modified with some self learning ability) may work, but the control system, and all the required sensors to do it would significantly add to cost and complexity.
Looking positively at the basics of a simple electric boost system...Control of motor speed is not a problem elsewhere and should not be a huge problem here. Motors can be controlled by PWM, frequency, voltage, amperage, or electro/mechanical configuration. That the motor(s) even need minute control is far from proven. Operation independent of engine RPM would offer significant advantage.
Taking the .4 second spool-up time and RPM at face value, it needs to be considered that the time between 0.0 and .4 is not lost. The time of .2 seconds would have the motor spinning at 25 to 35K. At any rate, the boost from an electric air pump can out accelerate the engine or driver’s needs. A significant amount of energy can be saved by limiting the motor/pump performance to the level of other components.
The mention of more than one air pump in my last post, in the context it was presented, was intended to lead those with imagination to the possibility of having more than one electric air pump. There is no reason that pumping of air can’t or shouldn’t be progressive. A motor/half-turbo setup is very compact. Having two or even more is not impractical. Using a smaller unit for each pair of cylinders or even a unit per cylinder, is not out of the question.
Yes I agree Fabrico, I doubt if most average drivers could actually move the throttle to fully open in 0.2 seconds anyway. Acceleratin time of the electric motor is really just a case of throwing more electrical power (and cooling) at the problem. But a viable control strategy still remains the biggest hurdle in my mind.
I have heard many people suggest that when a mechanical (electric?) supercharger is combined with a turbo, the supercharger can be switched off once the turbo has reached full boost. But can it?
If the heavily loaded engine is accelerating under boost conditions, and the supercharger is providing an appreciable proportion of that boost, a moments thought will tell you that you cannot simply suddenly just switch the supercharger off. The very sudden drop off in boost, and engine torque would be quite disconcerting.
I see the control problem not during the initial acceleration phase of an electric supercharger, but how the heck do you control it in such a way that it does not have to run continuously while the engine is in boost? If that is true, then the exhaust driven turbo really becomes redundant.
The whole concept of electric supercharging is really to improve transient response and drivability. But I see it as becoming more of a giant liability to drivability. No doubt it could be made to taper off gradually so the turbo and wastegate could catch up. But that can only really be done smoothly when the whole system is running near steady state.
Accelerating up through the gears will not present much of an opportunity to turn off the electric assist. Running it almost continuously for repeated long bursts will present a fearsome electrical load. That power must come from somewhere, and we are right back where we started with high parasitic drive losses into the electrical charging system.
I still have very serious doubts that this electric centrifugal idea can beat a direct driven positive displacement turbo assist.
The roots blower will already be up to speed when you open the throttle. The bypass system closes proportionally as the throttle moves, and the whole induction system pressurises within a few turns of the blower. With the bypass fully open parasitic drive losses are almost zero. Power to run the supercharger is only absorbed during actual open throttle acceleration. There are no transient or flow control problems either. And it is simple.
Funnily enough a roots blower is preferred in this application to a screw blower. Required supercharger pressure ratio will be quite low, and it will be resonably efficient. But the big advantage of the roots blower is that it can be completely unloaded by reducing the pressure differential across it to effectively zero. A screw blower has some internal compression. It therefor always absorbs power crushing the air between the rotors, even when differential pressure across the blower is zero. A screw blower will be much better in every other respect, but the much lower fully unloaded drive losses make a roots blower more desirable where fuel economy is extremely important.
I know I am heavily biased with this, but I still cannot see an electric assist being able to beat it, either for transient response, energy efficiency, or cost.
Just a final word on the functioning of the bypass system. It will be appreciated that the rotors of a roots blower do not directly compress the air. If inlet pressure and outlet pressure are identical, the rotors just spin freely around inside the casing, and no work is done.
It will also be appreciated that as soon as the air is throttled, either at inlet or outlet, a pressure differential will be created. The blower will then consume additional drive torque. It will be working against the resistance of the closed throttle and will consume significant drive power in doing so.
That is exactly the situation that exists during idle or small throttle highway operation. The supercharger is working against an almost fully closed throttle. Opening an air bypass path directly around the supercharger is just as effective as de-clutching, but it has the very great advantage of being ready for instant action by already having the rotors running at full operating speed.
I very much doubt if any electric motor could beat that instant state of readiness of an already up to speed roots blower !!
And one final point. I have heard it claimed that a supercharger will become restrictive once the turbo is boosting. That is never true in practice. If supercharger discharge pressure is higher than supercharger intake pressure, it is certainly cannot be acting as a restriction!
I have heard many people suggest that when a mechanical (electric?) supercharger is combined with a turbo, the supercharger can be switched off once the turbo has reached full boost. But can it?
If the heavily loaded engine is accelerating under boost conditions, and the supercharger is providing an appreciable proportion of that boost, a moments thought will tell you that you cannot simply suddenly just switch the supercharger off. The very sudden drop off in boost, and engine torque would be quite disconcerting.
I see the control problem not during the initial acceleration phase of an electric supercharger, but how the heck do you control it in such a way that it does not have to run continuously while the engine is in boost? If that is true, then the exhaust driven turbo really becomes redundant.
The whole concept of electric supercharging is really to improve transient response and drivability. But I see it as becoming more of a giant liability to drivability. No doubt it could be made to taper off gradually so the turbo and wastegate could catch up. But that can only really be done smoothly when the whole system is running near steady state.
Accelerating up through the gears will not present much of an opportunity to turn off the electric assist. Running it almost continuously for repeated long bursts will present a fearsome electrical load. That power must come from somewhere, and we are right back where we started with high parasitic drive losses into the electrical charging system.
I still have very serious doubts that this electric centrifugal idea can beat a direct driven positive displacement turbo assist.
The roots blower will already be up to speed when you open the throttle. The bypass system closes proportionally as the throttle moves, and the whole induction system pressurises within a few turns of the blower. With the bypass fully open parasitic drive losses are almost zero. Power to run the supercharger is only absorbed during actual open throttle acceleration. There are no transient or flow control problems either. And it is simple.
Funnily enough a roots blower is preferred in this application to a screw blower. Required supercharger pressure ratio will be quite low, and it will be resonably efficient. But the big advantage of the roots blower is that it can be completely unloaded by reducing the pressure differential across it to effectively zero. A screw blower has some internal compression. It therefor always absorbs power crushing the air between the rotors, even when differential pressure across the blower is zero. A screw blower will be much better in every other respect, but the much lower fully unloaded drive losses make a roots blower more desirable where fuel economy is extremely important.
I know I am heavily biased with this, but I still cannot see an electric assist being able to beat it, either for transient response, energy efficiency, or cost.
Just a final word on the functioning of the bypass system. It will be appreciated that the rotors of a roots blower do not directly compress the air. If inlet pressure and outlet pressure are identical, the rotors just spin freely around inside the casing, and no work is done.
It will also be appreciated that as soon as the air is throttled, either at inlet or outlet, a pressure differential will be created. The blower will then consume additional drive torque. It will be working against the resistance of the closed throttle and will consume significant drive power in doing so.
That is exactly the situation that exists during idle or small throttle highway operation. The supercharger is working against an almost fully closed throttle. Opening an air bypass path directly around the supercharger is just as effective as de-clutching, but it has the very great advantage of being ready for instant action by already having the rotors running at full operating speed.
I very much doubt if any electric motor could beat that instant state of readiness of an already up to speed roots blower !!
And one final point. I have heard it claimed that a supercharger will become restrictive once the turbo is boosting. That is never true in practice. If supercharger discharge pressure is higher than supercharger intake pressure, it is certainly cannot be acting as a restriction!
A lot of the control instability predicted here would be self imposed, if the control designer chooses to assign boost or MAP to the primary loop. MAF is a better choice for P and assign MAP to any required sub-loops needed for system constraints. As stated previously, boost is nonlinear to engine V.E. as well as compressor power requirements. MAF along with compressor speed, engine speed, and throttle rate ( emphasis on rate) are probably better elements of choice in the prime control loop.
Again, the E charger is only of interest if it can more effectively achieve driver intent while adhering to system constraints, either in conjunction with or in lieu of a turbocharger. It's important not to get to myopic about the E charger as the only indepentant boosting device solution. If a centrifical compressor is driven with an efficiant continously variable drive unit, the E chargers attributes are easily halfed. If this variable drive unit is hydraulically coupled to the compressor, it might also be possable to divert crank power to a hydraulic accumulator on braking. This has it's own ineffeciencies to deal with, but probably on par with the crank to alternator to motor to compressor power path of most proposed E charger systems.
Again, the E charger is only of interest if it can more effectively achieve driver intent while adhering to system constraints, either in conjunction with or in lieu of a turbocharger. It's important not to get to myopic about the E charger as the only indepentant boosting device solution. If a centrifical compressor is driven with an efficiant continously variable drive unit, the E chargers attributes are easily halfed. If this variable drive unit is hydraulically coupled to the compressor, it might also be possable to divert crank power to a hydraulic accumulator on braking. This has it's own ineffeciencies to deal with, but probably on par with the crank to alternator to motor to compressor power path of most proposed E charger systems.
Good points Jim.
I still think any feedback system would fall far short of what would be required.
As an example, it would be like trying to control engine fuel flow purely from the output of an oxygen sensor and nothing else. No matter what you do, any feedback system can only respond once the system output has changed. Getting both speed and stability with something like that except under ideal, completely steady state conditions would be all but impossible.
A normal engine management system is a feedforward system. It looks at all the inputs, and engine fuel requirements are predicted and then applied. Tuning the ECU is about getting that prediction right, over a very wide combination of inputs. And, feedforward is never a closed loop system, so it cannot become unstable. The output may be wrong, but it never goes totally nuts with cyclic instability.
I use this example only to illustrate the difference between feedback, and feedforward, for those here not familiar with the terms.
Something similar would be needed to control this electric supercharger. Characteristics of supercharger, turbo, and engine would need to be modeled in software. Not just static values, but the dynamic ones too. Power to the supercharger would need to be controlled in a predictive manner.
Waiting for boost to fluctuate, and then attempting to correct it somehow is just not going to work. If it over corrects, the system could easily become unstable. How much, and how fast to correct are the two basic rules of feedback loop design and tuning. Nested control loops, with extreme non linearities and significant time delays, are an absolute nightmare.
I still think any feedback system would fall far short of what would be required.
As an example, it would be like trying to control engine fuel flow purely from the output of an oxygen sensor and nothing else. No matter what you do, any feedback system can only respond once the system output has changed. Getting both speed and stability with something like that except under ideal, completely steady state conditions would be all but impossible.
A normal engine management system is a feedforward system. It looks at all the inputs, and engine fuel requirements are predicted and then applied. Tuning the ECU is about getting that prediction right, over a very wide combination of inputs. And, feedforward is never a closed loop system, so it cannot become unstable. The output may be wrong, but it never goes totally nuts with cyclic instability.
I use this example only to illustrate the difference between feedback, and feedforward, for those here not familiar with the terms.
Something similar would be needed to control this electric supercharger. Characteristics of supercharger, turbo, and engine would need to be modeled in software. Not just static values, but the dynamic ones too. Power to the supercharger would need to be controlled in a predictive manner.
Waiting for boost to fluctuate, and then attempting to correct it somehow is just not going to work. If it over corrects, the system could easily become unstable. How much, and how fast to correct are the two basic rules of feedback loop design and tuning. Nested control loops, with extreme non linearities and significant time delays, are an absolute nightmare.
I dont see it as a problem,
After all, closed loop boost control can, has and is quite easily done elsewhere with an ECU controlled PWM actuator, so why not here?
Even with a turbocompounded system I dont see how there would be a problem?
Warpspeed, you seem to be implying that there are precious few closed loop control systems in a modern engine management system - is that a statement you have thought thorough?
What is the worry about the 'characteristics of the supercharger?' Surely the amount of air that enters the engine is what matters? Which is easily and effectively calculated without ever needing to know what the supercharger is doing.
A properly calibrated torque based control system would be more than adequate to control this system - gone are the days of simple speed/density or alpha/n control systems.
MS
After all, closed loop boost control can, has and is quite easily done elsewhere with an ECU controlled PWM actuator, so why not here?
Even with a turbocompounded system I dont see how there would be a problem?
Warpspeed, you seem to be implying that there are precious few closed loop control systems in a modern engine management system - is that a statement you have thought thorough?
What is the worry about the 'characteristics of the supercharger?' Surely the amount of air that enters the engine is what matters? Which is easily and effectively calculated without ever needing to know what the supercharger is doing.
A properly calibrated torque based control system would be more than adequate to control this system - gone are the days of simple speed/density or alpha/n control systems.
MS
Ahh, fresh air!
Specific comparisons are useful, but constant, boundless, inaccurate, repetitive, negativity is not. It also does not help for one to make up unresonable scenarios then talk about how impossible they are to solve.
I also don't see much of a problem with motor control. Simple matching of the motor/turbine to engine breating needs would eliminate extremes. And, dare I mention it, there is no reason the air pump can't be fitted with a re-circulating bypass valve.
Electric boost is perhaps at it's very best and simplest when piggy-backed onto a turbo charger. Using the flap valve method I described earlier, all airflow transistions are perfectly seamless and the electric motor can simply be turned off with no ill effects.
Upon takeoff and until it runs out of steam, an electric air pump can certainly keep pace with a typical direct drive blower setup, with or without turbo assist.
globi5
Mechanical
- Oct 10, 2005
- 281
- 0
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Regarding parasitic loss:
I guess I should have said: There's no need for parasitic loss at full throttle, which is the point I tried to make, since you can get the same amount of power with less boost or you can get the same amount of power with same boost and a smaller engine.
Also, if an engine has lots of low end torque (which an electrically assisted supercharger can have), one can also drive lower geared = reduced fuel consumption.
If engine downsizing is the future, electrically assisted supercharging or electrically assisted turbocharging or a combination of both could be part of this future:
Fuel Economy, CO2 and Cost Benefits
I guess I should have said: There's no need for parasitic loss at full throttle, which is the point I tried to make, since you can get the same amount of power with less boost or you can get the same amount of power with same boost and a smaller engine.
Also, if an engine has lots of low end torque (which an electrically assisted supercharger can have), one can also drive lower geared = reduced fuel consumption.
If engine downsizing is the future, electrically assisted supercharging or electrically assisted turbocharging or a combination of both could be part of this future:
Fuel Economy, CO2 and Cost Benefits
globi5
Mechanical
- Oct 10, 2005
- 281
- 0
- 0
...and if the battery is charged while cruising, pumping losses are also reduced.
Also, engines can deal with more boost at low rpms and/or higher compression ratio since heat production is lower at low rpms and so is detonation-risk. (Assuming torque fluctuations are as in a Diesel engine taken care of).
Also, engines can deal with more boost at low rpms and/or higher compression ratio since heat production is lower at low rpms and so is detonation-risk. (Assuming torque fluctuations are as in a Diesel engine taken care of).
Feedforward or preact can be used to describe an attribute of a closed loop systems and does not necessarily need to describe an alternative to a closed loop system. Set points and Kp, Ki,Kd can be static or dynamic in a PID loop. Feedforward (preact) can be added to the loop either by dynamically trimming on the Kpid coefficients or by trimming set points to Best Possible during transient conditions for example. Electronic boost controllers for example have used every possible combination of control strategies ever thunk up, with good, to disastrous results. Adding feedforward to a boost controller loop is normally helpful but tricky, in that you are giving the loop information that it is not capable of anticipating on it's on and commanding it to act on it in a specific way. Once you incorporate this expert system, you are responsible for all unpredicted scenarios that the end user will get into. If not well thought out, it is possible to cause dangerous boost spikes by upsetting the underlying loop. Typically the designer sets up a learning session the installer runs the car through to learn the rate boost climbs at full throttle and uses this information in various ways during future operation. Unless this is done under all conditions (IE each gear, up hill, down hill, etc) you may have added information the system is expected to assume correct under ALL conditions, building a land mine into the soup. Feedforward, fussy logic, expert syst., PID, cascading PID are tools in the box to be mixed as needed normally never the eloquent solution alone.
Fabrico, the bypass your describing does work, I have one from a Penta/Volvo somethingorother we used during testing of the Hydracharger. I dug it out this morning and took a picture of it, I think being a Penta it is from a marine application, maybe someone else would know if they saw it. It has a 3.25" inlet checked by a flopper door, a 3.25" outlet, and a 3" y'd inlet for the compressed feed. Here is the picture.
Fabrico, the bypass your describing does work, I have one from a Penta/Volvo somethingorother we used during testing of the Hydracharger. I dug it out this morning and took a picture of it, I think being a Penta it is from a marine application, maybe someone else would know if they saw it. It has a 3.25" inlet checked by a flopper door, a 3.25" outlet, and a 3" y'd inlet for the compressed feed. Here is the picture.
O/k fair enough guys, you all make it sound so very simple. I have been struggling with power electronics, control systems and feedback loops for most of my working life.
Anyhow, back on topic. Does anyone know if these electric superchargers have been successfully installed on a vehicle yet ?
If it is all so very simple to apply, where are the road test results ?
Anyhow, back on topic. Does anyone know if these electric superchargers have been successfully installed on a vehicle yet ?
If it is all so very simple to apply, where are the road test results ?
No need to struggle Warp. And none of us knows how simple or complicated it really has to be. Components have been around, but as far as I know, a comprehensive system is new technology.
I hope you don't mind posting your picture jimwolf, but that's just the kind of low tech, reliable components I've been talking about. The unit I worked with was a little more streamlined and had a position sensor for the door. The sensor told the controller that the turbocharger was taking over and to unplug the electric. Failsafe really.
There may be other things worthy of consideration. While turbochargers are a reliable way to more power, the only time they have low parasitic loss is when they are providing little or no boost. This is not helped by the fact that their design is compromised in having to satisfy a broad RPM range. An electric air boost system could allow for a more efficient turbo design.
I hope you don't mind posting your picture jimwolf, but that's just the kind of low tech, reliable components I've been talking about. The unit I worked with was a little more streamlined and had a position sensor for the door. The sensor told the controller that the turbocharger was taking over and to unplug the electric. Failsafe really.
There may be other things worthy of consideration. While turbochargers are a reliable way to more power, the only time they have low parasitic loss is when they are providing little or no boost. This is not helped by the fact that their design is compromised in having to satisfy a broad RPM range. An electric air boost system could allow for a more efficient turbo design.
Yes, all the electric boost systems I have seen so far are just a complete joke, like this one for instance:
But a high powered electric booster with real balls is quite a different matter altogether. I will watch this with growing interest.
I hate to be a wet blanket Fabrico, but I play it as I see it, based on my own knowledge and practical experience.
Anyhow, beware of using flaps and control valves with any centrifugal compressor. There is a belief that you can spin up a centrifugal compressor and use it to open a flap when developed pressure has become sufficient. It can certainly be done, but only with a bit of thought and some additional complication.
The problem is compressor surge. A centrifugal absolutely must have some minimum flow in order to work at all. It cannot develop pressure into a dead end against a flap. It will definitely need some sort of fairly generous air bleed system (which can later be closed).
It is always vastly easier to place a centrifugal in series with something else, rather than in parallel.
I really hope this is going to be taken as intended, as constructive advice, not as criticism.
But a high powered electric booster with real balls is quite a different matter altogether. I will watch this with growing interest.
I hate to be a wet blanket Fabrico, but I play it as I see it, based on my own knowledge and practical experience.
Anyhow, beware of using flaps and control valves with any centrifugal compressor. There is a belief that you can spin up a centrifugal compressor and use it to open a flap when developed pressure has become sufficient. It can certainly be done, but only with a bit of thought and some additional complication.
The problem is compressor surge. A centrifugal absolutely must have some minimum flow in order to work at all. It cannot develop pressure into a dead end against a flap. It will definitely need some sort of fairly generous air bleed system (which can later be closed).
It is always vastly easier to place a centrifugal in series with something else, rather than in parallel.
I really hope this is going to be taken as intended, as constructive advice, not as criticism.
rpmag
Automotive
- Oct 15, 2004
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Whilst it is not an electric supercharger by any means, the current Mannic hillclimb cars uses a system that I find ingenious. It uses a large turbocharger with its own fuel supply to burn, much like a gas turbine. This produces 23-30psi at idle to full rpm, with minimal engine lag.
Mind you it is a competiton car in hillclimbs, so durability and emissions are not a concern. It can be seen in the current racetech magazine, though it has been around for the past 5-6 years.
Mind you it is a competiton car in hillclimbs, so durability and emissions are not a concern. It can be seen in the current racetech magazine, though it has been around for the past 5-6 years.
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