Discussion
in my extremely limited understanding of all things spanner like:
Are all EV's detuned to improve range? - do the motors have anything in reserve?
Could you just increase the power which would decrease the range?
i was thinking about the ludicrous mode on the Tesla and wondered if that theory could be used on other models for a 'quick burst' ?
I get that there are limitations on what the motors/drive train can produce but similarly to mapping ICE cars, is there much wiggle room?
Are all EV's detuned to improve range? - do the motors have anything in reserve?
Could you just increase the power which would decrease the range?
i was thinking about the ludicrous mode on the Tesla and wondered if that theory could be used on other models for a 'quick burst' ?
I get that there are limitations on what the motors/drive train can produce but similarly to mapping ICE cars, is there much wiggle room?
In simple terms, the power of an electric motor is limited (fundamentally) by it's supply voltage and it's thermal impedance.
Because modern power electronics can control the motor current to very very close tollerances, most EVs will be running very close to the absolute maximum short term (ie not thermally limited) performance available at their chosen supply voltage. Long term performance (thermally limited) will simply be the maximum heat flux that the motor can experience before going over temperature, and that is broadly set by the mechanical architecture of the machine. (too hot, and the electrical insulation on the stator fails (bad!) and the Permanent Magnets lose their magnetism (bad!). Within a modern eMachine are various sensors that measure critical temperatures within the machine, and in conjunction with other temperatures that are modelled, the power electronics will automatically de-rate to prevent that sort of failure.
Practically speaking, there are Four main "choke" points in the system, any or all of which can be the limiting factor:
1) The battery - normally, a battery system is calibrated to be very safe to maximise it's life. As more real world useage data is gathered, OEMs are starting to push the limits a bit more as in the real world, battery desegregation has been much less than originally feared. Hence, if you could get access to the battery management control software, you could almost certainly pull more power than std from the battery (limiting factors could also be the fusing, current measurement devices and even things like connector capability). A complete change in string architecture (more series cells) could furnish a higher nominal voltage, supplying more power capability, but the knock on effect could be enormous (OnBoardCharger might not be rated for the extra votltage, nor the DC;DC that drives the LV battery (12v systems etc).
2) The Inverter - There is really no practical difference between short and long term capability for an inverter. Because the active silicon switching area is so small (just a couple of square cm of semiconductor are switching several hundred kW!) it effectively has no thermal inertia. Over current events for as little as 100uS (1/10,000th of a second!) can result in failure. Because power silicon is expensive, typically the inverter current limit is the systems primary design point and ultimate limiting factor. In conjunction, things like phase current sensors are sized for the max current capability, so they would almost certainly have to be modified or replaced with larger range devices if the current is increased. Best option here would be to replace at least the power section of the inverter with a higher rated one. Currently, most power silicon has been developed for the industrial sector, and hence comes in two voltage ratings (600v and 1200v) to suit the normal AC line supply peaks. Most EV's currently use 600V silicon, but all systems will leave at least a 20% headroom from peak battery voltage to allow for dynamic effects. Hence most EV sit around 400 odd volts nominally. This is climbing as OEMs gain experience and want to get more power (and efficiency) from their systems
3) The eMachine itself. The winding architecture, the max rotational speed capability, and the insulation rating are all specified for a nominal supply voltage. Although increases in supply voltage may not cause immediate catastrophic failure, the life of the eMachine will most likely be shortened. Thermally, the only real way to improve the long term perf is to force cool the machine, ie, fit a system that can feed a lower temperature coolant to the eMachine. The colder, the better! (although depending on the machines sealing / venting arrangements, avoiding a condensing atmosphere is advisable)
4) The control system - Here's the biggy. All the system components tend to be controlled, and crucially, monitored by some higher level supervisor. That controller will monitor the reported state of each part, and generally can turn everything off if it senses any significant off-nominal behavior. Ie, say you crudely shunt the phase current sensors in the inverter by 10% (ie, they will report 10% less current than is actually flowing in the motor phases). You (may) get an extra 10% machine torque, but chances are, when the battery managements reports 10% more current for any given load the supervisor will call foul and open the safety contactors! So, then you also need to shunt the battery current sensors by the same 10%. But now, you fuel gauge and battery SoC calculations are wrong, and who wants to drive an EV that stops dead unexpectedly when it hits the critical low battery voltage limit before the dash says you are out of juice! So, now you need to re-calibrate the SoC calcs in the supervisor too!
So, yes, EVs are eminently tuneable, but imo, it's such a PITA to do so, requiring multiple units to be physically modified and re-calibrated, why would you bother? And it's not like EVs are slow in the first place. It's also worth noting that you are very, very unlikely to be able to increase the system efficiency with a re-map (unlike for some ICEs, where there is a trade off between tailpipe pollutants and fuel consumption). Typically, most current systems are mapped to within 0.5% of absolute optimum, so on say a 100mile range EV, an remap might get you another half mile down the road...
Because modern power electronics can control the motor current to very very close tollerances, most EVs will be running very close to the absolute maximum short term (ie not thermally limited) performance available at their chosen supply voltage. Long term performance (thermally limited) will simply be the maximum heat flux that the motor can experience before going over temperature, and that is broadly set by the mechanical architecture of the machine. (too hot, and the electrical insulation on the stator fails (bad!) and the Permanent Magnets lose their magnetism (bad!). Within a modern eMachine are various sensors that measure critical temperatures within the machine, and in conjunction with other temperatures that are modelled, the power electronics will automatically de-rate to prevent that sort of failure.
Practically speaking, there are Four main "choke" points in the system, any or all of which can be the limiting factor:
1) The battery - normally, a battery system is calibrated to be very safe to maximise it's life. As more real world useage data is gathered, OEMs are starting to push the limits a bit more as in the real world, battery desegregation has been much less than originally feared. Hence, if you could get access to the battery management control software, you could almost certainly pull more power than std from the battery (limiting factors could also be the fusing, current measurement devices and even things like connector capability). A complete change in string architecture (more series cells) could furnish a higher nominal voltage, supplying more power capability, but the knock on effect could be enormous (OnBoardCharger might not be rated for the extra votltage, nor the DC;DC that drives the LV battery (12v systems etc).
2) The Inverter - There is really no practical difference between short and long term capability for an inverter. Because the active silicon switching area is so small (just a couple of square cm of semiconductor are switching several hundred kW!) it effectively has no thermal inertia. Over current events for as little as 100uS (1/10,000th of a second!) can result in failure. Because power silicon is expensive, typically the inverter current limit is the systems primary design point and ultimate limiting factor. In conjunction, things like phase current sensors are sized for the max current capability, so they would almost certainly have to be modified or replaced with larger range devices if the current is increased. Best option here would be to replace at least the power section of the inverter with a higher rated one. Currently, most power silicon has been developed for the industrial sector, and hence comes in two voltage ratings (600v and 1200v) to suit the normal AC line supply peaks. Most EV's currently use 600V silicon, but all systems will leave at least a 20% headroom from peak battery voltage to allow for dynamic effects. Hence most EV sit around 400 odd volts nominally. This is climbing as OEMs gain experience and want to get more power (and efficiency) from their systems
3) The eMachine itself. The winding architecture, the max rotational speed capability, and the insulation rating are all specified for a nominal supply voltage. Although increases in supply voltage may not cause immediate catastrophic failure, the life of the eMachine will most likely be shortened. Thermally, the only real way to improve the long term perf is to force cool the machine, ie, fit a system that can feed a lower temperature coolant to the eMachine. The colder, the better! (although depending on the machines sealing / venting arrangements, avoiding a condensing atmosphere is advisable)
4) The control system - Here's the biggy. All the system components tend to be controlled, and crucially, monitored by some higher level supervisor. That controller will monitor the reported state of each part, and generally can turn everything off if it senses any significant off-nominal behavior. Ie, say you crudely shunt the phase current sensors in the inverter by 10% (ie, they will report 10% less current than is actually flowing in the motor phases). You (may) get an extra 10% machine torque, but chances are, when the battery managements reports 10% more current for any given load the supervisor will call foul and open the safety contactors! So, then you also need to shunt the battery current sensors by the same 10%. But now, you fuel gauge and battery SoC calculations are wrong, and who wants to drive an EV that stops dead unexpectedly when it hits the critical low battery voltage limit before the dash says you are out of juice! So, now you need to re-calibrate the SoC calcs in the supervisor too!
So, yes, EVs are eminently tuneable, but imo, it's such a PITA to do so, requiring multiple units to be physically modified and re-calibrated, why would you bother? And it's not like EVs are slow in the first place. It's also worth noting that you are very, very unlikely to be able to increase the system efficiency with a re-map (unlike for some ICEs, where there is a trade off between tailpipe pollutants and fuel consumption). Typically, most current systems are mapped to within 0.5% of absolute optimum, so on say a 100mile range EV, an remap might get you another half mile down the road...
Max_Torque said:
In simple terms, the power of an electric motor is limited (fundamentally) by it's supply voltage and it's thermal impedance.
Because modern power electronics can control the motor current to very very close tollerances, most EVs will be running very close to the absolute maximum short term (ie not thermally limited) performance available at their chosen supply voltage. Long term performance (thermally limited) will simply be the maximum heat flux that the motor can experience before going over temperature, and that is broadly set by the mechanical architecture of the machine. (too hot, and the electrical insulation on the stator fails (bad!) and the Permanent Magnets lose their magnetism (bad!). Within a modern eMachine are various sensors that measure critical temperatures within the machine, and in conjunction with other temperatures that are modelled, the power electronics will automatically de-rate to prevent that sort of failure.
Practically speaking, there are Four main "choke" points in the system, any or all of which can be the limiting factor:
1) The battery - normally, a battery system is calibrated to be very safe to maximise it's life. As more real world useage data is gathered, OEMs are starting to push the limits a bit more as in the real world, battery desegregation has been much less than originally feared. Hence, if you could get access to the battery management control software, you could almost certainly pull more power than std from the battery (limiting factors could also be the fusing, current measurement devices and even things like connector capability). A complete change in string architecture (more series cells) could furnish a higher nominal voltage, supplying more power capability, but the knock on effect could be enormous (OnBoardCharger might not be rated for the extra votltage, nor the DC;DC that drives the LV battery (12v systems etc).
2) The Inverter - There is really no practical difference between short and long term capability for an inverter. Because the active silicon switching area is so small (just a couple of square cm of semiconductor are switching several hundred kW!) it effectively has no thermal inertia. Over current events for as little as 100uS (1/10,000th of a second!) can result in failure. Because power silicon is expensive, typically the inverter current limit is the systems primary design point and ultimate limiting factor. In conjunction, things like phase current sensors are sized for the max current capability, so they would almost certainly have to be modified or replaced with larger range devices if the current is increased. Best option here would be to replace at least the power section of the inverter with a higher rated one. Currently, most power silicon has been developed for the industrial sector, and hence comes in two voltage ratings (600v and 1200v) to suit the normal AC line supply peaks. Most EV's currently use 600V silicon, but all systems will leave at least a 20% headroom from peak battery voltage to allow for dynamic effects. Hence most EV sit around 400 odd volts nominally. This is climbing as OEMs gain experience and want to get more power (and efficiency) from their systems
3) The eMachine itself. The winding architecture, the max rotational speed capability, and the insulation rating are all specified for a nominal supply voltage. Although increases in supply voltage may not cause immediate catastrophic failure, the life of the eMachine will most likely be shortened. Thermally, the only real way to improve the long term perf is to force cool the machine, ie, fit a system that can feed a lower temperature coolant to the eMachine. The colder, the better! (although depending on the machines sealing / venting arrangements, avoiding a condensing atmosphere is advisable)
4) The control system - Here's the biggy. All the system components tend to be controlled, and crucially, monitored by some higher level supervisor. That controller will monitor the reported state of each part, and generally can turn everything off if it senses any significant off-nominal behavior. Ie, say you crudely shunt the phase current sensors in the inverter by 10% (ie, they will report 10% less current than is actually flowing in the motor phases). You (may) get an extra 10% machine torque, but chances are, when the battery managements reports 10% more current for any given load the supervisor will call foul and open the safety contactors! So, then you also need to shunt the battery current sensors by the same 10%. But now, you fuel gauge and battery SoC calculations are wrong, and who wants to drive an EV that stops dead unexpectedly when it hits the critical low battery voltage limit before the dash says you are out of juice! So, now you need to re-calibrate the SoC calcs in the supervisor too!
So, yes, EVs are eminently tuneable, but imo, it's such a PITA to do so, requiring multiple units to be physically modified and re-calibrated, why would you bother? And it's not like EVs are slow in the first place. It's also worth noting that you are very, very unlikely to be able to increase the system efficiency with a re-map (unlike for some ICEs, where there is a trade off between tailpipe pollutants and fuel consumption). Typically, most current systems are mapped to within 0.5% of absolute optimum, so on say a 100mile range EV, an remap might get you another half mile down the road...
If i said i was hoping you'd be one of the people to contribute to this thread when i originally posted, it wouldn't be a lie Because modern power electronics can control the motor current to very very close tollerances, most EVs will be running very close to the absolute maximum short term (ie not thermally limited) performance available at their chosen supply voltage. Long term performance (thermally limited) will simply be the maximum heat flux that the motor can experience before going over temperature, and that is broadly set by the mechanical architecture of the machine. (too hot, and the electrical insulation on the stator fails (bad!) and the Permanent Magnets lose their magnetism (bad!). Within a modern eMachine are various sensors that measure critical temperatures within the machine, and in conjunction with other temperatures that are modelled, the power electronics will automatically de-rate to prevent that sort of failure.
Practically speaking, there are Four main "choke" points in the system, any or all of which can be the limiting factor:
1) The battery - normally, a battery system is calibrated to be very safe to maximise it's life. As more real world useage data is gathered, OEMs are starting to push the limits a bit more as in the real world, battery desegregation has been much less than originally feared. Hence, if you could get access to the battery management control software, you could almost certainly pull more power than std from the battery (limiting factors could also be the fusing, current measurement devices and even things like connector capability). A complete change in string architecture (more series cells) could furnish a higher nominal voltage, supplying more power capability, but the knock on effect could be enormous (OnBoardCharger might not be rated for the extra votltage, nor the DC;DC that drives the LV battery (12v systems etc).
2) The Inverter - There is really no practical difference between short and long term capability for an inverter. Because the active silicon switching area is so small (just a couple of square cm of semiconductor are switching several hundred kW!) it effectively has no thermal inertia. Over current events for as little as 100uS (1/10,000th of a second!) can result in failure. Because power silicon is expensive, typically the inverter current limit is the systems primary design point and ultimate limiting factor. In conjunction, things like phase current sensors are sized for the max current capability, so they would almost certainly have to be modified or replaced with larger range devices if the current is increased. Best option here would be to replace at least the power section of the inverter with a higher rated one. Currently, most power silicon has been developed for the industrial sector, and hence comes in two voltage ratings (600v and 1200v) to suit the normal AC line supply peaks. Most EV's currently use 600V silicon, but all systems will leave at least a 20% headroom from peak battery voltage to allow for dynamic effects. Hence most EV sit around 400 odd volts nominally. This is climbing as OEMs gain experience and want to get more power (and efficiency) from their systems
3) The eMachine itself. The winding architecture, the max rotational speed capability, and the insulation rating are all specified for a nominal supply voltage. Although increases in supply voltage may not cause immediate catastrophic failure, the life of the eMachine will most likely be shortened. Thermally, the only real way to improve the long term perf is to force cool the machine, ie, fit a system that can feed a lower temperature coolant to the eMachine. The colder, the better! (although depending on the machines sealing / venting arrangements, avoiding a condensing atmosphere is advisable)
4) The control system - Here's the biggy. All the system components tend to be controlled, and crucially, monitored by some higher level supervisor. That controller will monitor the reported state of each part, and generally can turn everything off if it senses any significant off-nominal behavior. Ie, say you crudely shunt the phase current sensors in the inverter by 10% (ie, they will report 10% less current than is actually flowing in the motor phases). You (may) get an extra 10% machine torque, but chances are, when the battery managements reports 10% more current for any given load the supervisor will call foul and open the safety contactors! So, then you also need to shunt the battery current sensors by the same 10%. But now, you fuel gauge and battery SoC calculations are wrong, and who wants to drive an EV that stops dead unexpectedly when it hits the critical low battery voltage limit before the dash says you are out of juice! So, now you need to re-calibrate the SoC calcs in the supervisor too!
So, yes, EVs are eminently tuneable, but imo, it's such a PITA to do so, requiring multiple units to be physically modified and re-calibrated, why would you bother? And it's not like EVs are slow in the first place. It's also worth noting that you are very, very unlikely to be able to increase the system efficiency with a re-map (unlike for some ICEs, where there is a trade off between tailpipe pollutants and fuel consumption). Typically, most current systems are mapped to within 0.5% of absolute optimum, so on say a 100mile range EV, an remap might get you another half mile down the road...
Thanks Max - do you think ICE mapping had the same 'kind' of barriers when they first started exploring tuning modern engines?
I think the many systems on modern ice cars would be similar to the above, ie seeing odd readings from other 'departments' - raising rev limiter would be one as an example.
With regard to 'fast enough' ...
its NEVER fast enough
i wouldn't mind exploring upgrading the brakes and chassis as these seem to be the limiting factor to anything spirited
There is a small degree of "tuning" between some of the various iterations of Tesla aren't there?
Is Ludicrous mode anything more than a software tweak?
And, not to do with the motors, but the batteries, the range can be limited by a software change too
https://cleantechnica.com/2017/09/09/tesla-unlocks...
Is Ludicrous mode anything more than a software tweak?
And, not to do with the motors, but the batteries, the range can be limited by a software change too
https://cleantechnica.com/2017/09/09/tesla-unlocks...
JPJPJP said:
Is Ludicrous mode anything more than a software tweak?
Ludicrous mode involves some special hardware, too.http://bgr.com/2015/07/18/tesla-model-s-ludicrous-...
PixelpeepS3 said:
Thanks Max - do you think ICE mapping had the same 'kind' of barriers when they first started exploring tuning modern engines?
The difference is that engine tuning started well before cars well electronically controlled. What i mean is that people learn (mostly via trial and error, often a LOT of error) how to mechanically modify an engine to make more power, but that mostly happened when engines were very simple and very un-optmised. Back in the day, a carbs and points engine might have wheazed out 50 bhp/litre, so with some simple tweaking perhaps 75 bhp/litre was availible, ie big improvements for simple changes.Then as engines got more complex, electronically managed and more optimised, the only reason re-mapping became popular is because of turbo charged engines being dominant. No one would bother re-mapping an NA engine these days, because they would be lucky to find even 5bhp, as the base engine is incredibly well optimised from the factor. ie, alot of work for little gain, and that's where we have "come in" with EV's. Extremely well optmised from the factor and controlled by a very complex system.
PixelpeepS3 said:
I think the many systems on modern ice cars would be similar to the above, ie seeing odd readings from other 'departments' - raising rev limiter would be one as an example.
I agree than modern ICEs are difficult to tune conventionally as well, especially if you want to maintain the rest of the support systems operating as well as they did from the factory (DSC/Cruise/ABS/Trans etc). Over the last 10 years the engine management system has ceased being a stand-alone controller and is now integrated into the vehicle systems, exchanging data with a host of other systems that all rely on the quality and accuracy of that data.But the fact remains, that because an electric powertrain is so repeatable and stab;e, broadly un-affected by the myriad influences that effect an ICE powertrain (fuel quality, ambient air temp & Pressure, coolant and oil temp, hardware variations etc etc), the monitoring limits are set much closer to the average operating state, meaning the window for changes to occur before some part of the system spots the change is much, much smaller.
JPJPJP said:
There is a small degree of "tuning" between some of the various iterations of Tesla aren't there?
Is Ludicrous mode anything more than a software tweak?
And, not to do with the motors, but the batteries, the range can be limited by a software change too
https://cleantechnica.com/2017/09/09/tesla-unlocks...
it is likely, imo, that more platforms and models will share a similar hardware set as EVs gain momentum. This means that there is more chance than Market Position will be set by software parameters than hardware ones. For example, you might be able to buy a car with 3 power options, but all will share identical hardware in order to keep costs down. This means that electronic tuning might be more worthwhile, as the limit will be a basic software limit. However, having said that, limiting factors for parts that are currently very expensive (battery cells for example) will mean that for at least a few years, low spec EVs (low power) will have less battery fitted than high power ones. As battery costs tumble, and range expectations continue to rise, i suspect most passenger cars will actually end up with a similar sized battery, and a "long range battery" is almost certainly a "high power" one as well.......Is Ludicrous mode anything more than a software tweak?
And, not to do with the motors, but the batteries, the range can be limited by a software change too
https://cleantechnica.com/2017/09/09/tesla-unlocks...
Max_Torque said:
JPJPJP said:
There is a small degree of "tuning" between some of the various iterations of Tesla aren't there?
Is Ludicrous mode anything more than a software tweak?
And, not to do with the motors, but the batteries, the range can be limited by a software change too
https://cleantechnica.com/2017/09/09/tesla-unlocks...
it is likely, imo, that more platforms and models will share a similar hardware set as EVs gain momentum. This means that there is more chance than Market Position will be set by software parameters than hardware ones. For example, you might be able to buy a car with 3 power options, but all will share identical hardware in order to keep costs down. This means that electronic tuning might be more worthwhile, as the limit will be a basic software limit. However, having said that, limiting factors for parts that are currently very expensive (battery cells for example) will mean that for at least a few years, low spec EVs (low power) will have less battery fitted than high power ones. As battery costs tumble, and range expectations continue to rise, i suspect most passenger cars will actually end up with a similar sized battery, and a "long range battery" is almost certainly a "high power" one as well.......Is Ludicrous mode anything more than a software tweak?
And, not to do with the motors, but the batteries, the range can be limited by a software change too
https://cleantechnica.com/2017/09/09/tesla-unlocks...
Tesla's are getting close to realistic limits off the line, they're already pulling well over 1G and hitting 60 in mid 2's. My wife gets lightheaded if I do a launch and mines only a P90DL.
I think tuning wise the benefits would be in improved suspension and maybe something to help at higher speeds where they tail off quite quickly relative to low speed performance
Heres Johnny said:
I think tuning wise the benefits would be in improved suspension and maybe something to help at higher speeds where they tail off quite quickly relative to low speed performance
I agree I think the main market for tuning EVs in the future will be handling and stopping based as they are the areas that could be quite easily improved with Tesla at least. Until of course as has been said we get to the point of battery sharing between models and manufacturers.Do we think in the future the software will be tuned for different characters for instance in the VAG group I doubt they will want the Mulsanne having the same neck snapping acceleration as the latest Lambo or Porsche? Or will this come from weight reduction etc?
I might be wrong but the rumours are that the Porsche mission E is going to have a 2 speed gearbox for better range at higher speeds, apparently targeting 275 miles at high speed? I have no idea how that would work as I can't pretend to be an engineering or EV expert. Read about it in the latest CAR magazine if anyone is interested.
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