# Amplifying output of industrial or Ebike BLDC controller to suit electric car.



## JeffAU (Jul 30, 2020)

Hi, any thoughts on the Idea. Im new to the forum and the concept of doing an EV conversion. Im a former audio technician and have electronic trade in Australia. The more I read into it, it seems like the output of a controller/inverter is basically the same as an audio amplifier, just bigger and 3 channels (3 phase) instead of 2 (stereo). I feel capable of building this section of the controller and heatsinks, and liquid cooling as I also have plumbing experience (mainly at home but can solder quite well and seal/join copper pipes. Im just not good with the logic/brain board with all the programming etc.

I am also thinking of a 3 motor design (2 rear axle and 1 front - Im converting an old series 3 Land Rover and thinking of having on road all wheel drive as well as 4 wheel regen braking as well as leaving its original gearbox and transfer case in for off road mechanical 4 wheel drive so having 3 motors and 3 controllers provides good backup in case one or even two fail when off road. Ideally having 3 of each means I would like to keep the design as cheap as possible. Im even considering building my own motors and repurposing old front loader washing machine drum/barrels as waterproofing (with motors inside waterproof drum casing, and air intake, for additional air cooling, from up high or snorkel, connected via existing door seal to where front loader door was) for off road. I will post separately about motors when I have more details.

My thoughts on the controllers are to amplify the output of something like this:









I would need to check reviews about whichever smaller controller I use to amplify and make sure this and the amplifier I build supports the maximum speed/frequency I want the motor run at based on speed and number of coils in circumference /3 etc. as well as its quality/reliability.

Anyone tried this idea before?


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## JeffAU (Jul 30, 2020)

Sorry If I’ve caused confusion about design of the car. All 3 motors will be under the bonnet. The 2 rear drive motors will connect to existing transmission and front drive motor will connect to front drive shaft where it connects to transfer case - this one will be belt or chain driven and this motor will only be powered when transfer case is in neutral and car is in matching gear for rear wheels (mainly on road but may be used to provide extra power/torque when mechanical 4 wheel drive is in use if this works , but probably won’t be the same gear ratio when in low range 4 wheel drive so not sure.

Sorry my design is complicated but will post separately when I have the design drawn up and motor type sellected.


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## JeffAU (Jul 30, 2020)

Another question on this if anyone knows. Im guessing the smaller controller I use for this should be pure sine wave. Does anyone know if this applies to BLDC or EV inverters? Just been looking at mains/power inverters lately and pure sine wave definitely more efficient, and running when powering synchronous motors designed for mains voltage.


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## Isaac97 (Jun 3, 2019)

Hi,
I suggest you take a look at Eric Tischer's EV build. He took an industrial VFD and used it to power his large Siemens induction motor. The Electric Passat

Is there any reason you prefer 3 motors over a single one?


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## JeffAU (Jul 30, 2020)

Isaac97 said:


> Hi,
> I suggest you take a look at Eric Tischer's EV build. He took an industrial VFD and used it to power his large Siemens induction motor. The Electric Passat
> 
> Is there any reason you prefer 3 motors over a single one?


Isaac, Im thinking of building these motors:









Theyre only 45KW and I think my Landrover is going to need at least 100kw,

Rather than try to change the design to make it bigger, I figured, why have one when you can have three? - since Im building it myself on the cheap and will have the materials and tools anyway.

Also works better having balanced regen braking. I may just have one of the rear drive motors just switch on when its needed and save batteries by having rear driven one of these motors when not.


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## Isaac97 (Jun 3, 2019)

Oh, I have seen that article. Doubling or tripling them might work alright.
At those power levels you definitely need sine wave controllers. Either look at Eric Tischer's site or check out OpenInverter.


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## brian_ (Feb 7, 2017)

It appears that the plan is to use a small motor controller to drive a higher-capacity inverter - that's fundamentally unworkable. What you need to drive the inverter power stage is a pulse train for each phase to switch the IGBT devices on and off in pulse width modulated fashion, not an analog sine wave. Yes, you can treat this like an analog input to a switching-mode power amplifier, but that's a pile of unnecessary complication.

I suggest just buying one of the DIY inverter kits (so you don't need to design the controller, since that's what you're not familiar with) and building the whole thing.


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## JeffAU (Jul 30, 2020)

Thanks for the help and info. Was looking into Paul Holmes original AC inverter design which I came across on the instructables, but little info available on these now so I should look into it further or go with an alternative kit. Was considering a single nissan leaf motor and inverter for a little while but not redily available here in Australia and the only wreck I came across at auction went for $7000 although that was repairable write off - so gone back to the plan of building my own inverters and motors and sorcing bateries from alibaba.


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## Isaac97 (Jun 3, 2019)

brian_ said:


> It appears that the plan is to use a small motor controller to drive a higher-capacity inverter - that's fundamentally unworkable. What you need to drive the inverter power stage is a pulse train for each phase to switch the IGBT devices on and off in pulse width modulated fashion, not an analog sine wave. Yes, you can treat this like an analog input to a switching-mode power amplifier, but that's a pile of unnecessary complication.


Absolutely -- I may have misinterpreted Jeff's idea. My understanding was that OP wants to use the brain of the sine wave controller and just replace the powerstage -- Eric Tischer did that with an industrial VFD and an IGBT power stage back in 2008 or so.


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## brian_ (Feb 7, 2017)

Isaac97 said:


> Absolutely -- I may have misinterpreted Jeff's idea. My understanding was that OP wants to use the brain of the sine wave controller and just replace the powerstage -- Eric Tischer did that with an industrial VFD and an IGBT power stage back in 2008 or so.


That would make sense, if the controller logic is appropriate to drive the chosen power stage, but that wouldn't be "amplifying the output" of the complete controller, so it wasn't what I assumed. Jeff - any clarification?


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## JeffAU (Jul 30, 2020)

Sorry for the delay and confusion. I thought inverters work on the same theory as audio power amplifiers and basically turn a small sine wave created by the logic board and turn it into a much larger one in terms of watts or kilowatts. There is obviously more to driving a 3 phase motor to a loudspeaker coil.

Im basically looking for a low cost conversion for my recently purchased 1978 S3 Land Rover, especially where I am in Australia where the US$3000 conversation kits you see on eBay quickly turn into AU$5000 or more by the time you add shipping. Also, although Nissan Leafs have been sold in Australia since around 2010, finding used motors and wrecks are extremely rare and the only salvage vehicle I found at auction went for $7000

I think I’ve found a good source of batteries on Alibaba with good reviews and also received good feedback on the diysolarpower forum. I’ll post more about this in batteries section when I have more information on these when I hear back from the supplier.

My design has been changing from week to week but Ideally I would like to keep its original syncro gearbox and transfer case and add a main electric motor where the ICE used to be with or without the clutch - ideally without if this early syncro gearbox (Land Rover’s first) will handle gear changes with a stationary electric motor - I’ve got this idea from another article on this forum about clutch-less design.

I would also ideally like to add a second electric motor to the front drive shaft. It will most likely be added where the front drive shaft connects to the transfer case as the other end is moving with the suspension. This motor would be either belt driven (transfer case or CVT type multi-chain) or if its a double ended type and strong enough Ill add it in line and find a shorter drive shaft from another vehicle and leave a gap for it. This motor will be for on road all wheel drive (I plan to leave the original transfer case with low range to keep the vehicles off road capabilities but this front motor could be switched on momentarily as a boost of power for difficult off road situations but will be at a faster speed due to gear ratios) The main purpose of the front motor will be for 4 wheel Regen braking through as I think this is a lot safer and effective.

I’m now pretty much sold on Damien’s (EVBMW) Prius Gen 3 Dual Motor kit that is a new logic board for the original Prius inverter now as the Prius and it’s motors and inverters are one type of vehicle that is very easily sourced in Australia - they have been a vehicle of choice for taxi companies here for a long time now and you can even get a roadworthy vehicle for under $2000 now. Im thinking of getting a wreck at auction as I can get other useful bits such as the air con, accelerator pedal control and wiring - not sure about the batteries, I hear they are NIMH so will have to be a separate pack if they are any good. Probably good as a separate emergency battery to get out of trouble if my main battery goes flat though if they are still good.

I would be keen to hear if anyone here has had any experience with the Prius electric motors out of the trans-axles. I hear they are more difficult to work with due to being built in but confident about making a new casing - preferably waterproof if necessary. If I do go with the vehicle design with the extra front motor I’m not sure If I’ll try to split the two motors and use MG2 for main drive and MG1 for the additional front motor or buy 2 separate sets of these and kits and just use one complete set of these for each drive. Depends on power requirements as my vehicle is a fair bit larger and definitely a lot less aerodynamic than the Prius and I hope to use it for towing occasionally.


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## MattsAwesomeStuff (Aug 10, 2017)

JeffAU said:


> I’m not sure If I’ll try to split the two motors and use MG2 for main drive and MG1 for the additional front motor or buy 2 separate sets of these and kits and just use one complete set of these for each drive. Depends on power requirements as my vehicle is a fair bit larger and definitely a lot less aerodynamic than the Prius and I hope to use it for towing occasionally.


Nope. Don't do that.

The motors are all enclosed, fairly compact, into a gearbox. They are also not equally sized. You're going to need geardown for them anyway.

I'd keep the transaxles the same.

I wish you luck but I think you're biting off more than you can chew in terms of complexity here. And, you haven't seemed to consider battery much. Occasional towing is hopefully just around a yard or parking help, with 3 motor and inverter systems and a heavy vehicle and a low budget, you're just not going to have much for battery range.

Do note that Damien's dual-motor controller is a master-slave, not a twin master. That is, the second motor is given a mirror signal to the master, if one's on, the other's one, you don't have independent control.

The Prius Gen 3 controller is good for like 700 hp peak, limited only by your ability to cool it. Power is not an issue, though battery drain at massive power draw will be.

You might also want to look at the GS450H motor/gearbox combo from the Lexus. It looks like a normal tranny and bell housing, but has the motors and gearbox inside, and it's a decent amount beefier than the Prius units, and a lot easier to integrate into RWD.

Alternatively, there's an "MGR" which is a little baby motor as a diff, so if you just need "some" extra power on all wheels you could try that.

Damien has working controllers for all of those.


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## JeffAU (Jul 30, 2020)

Thanks Matt,

I might just start with a standard conversion of swapping out the ICE for a decent size motor and look at the additional front motor as an upgrade later on.

With the Prius Gen 3 dual Motor set up as one set of both motors connected just running as one main motor connected to input of the original manual gearbox, and just using a lower gear to drive, is there any info on continuous and peak power consumption, doing it this way? Also with Damien’s inverter controller, I would be keen to know if this can be driven with one of those motors only (whichever is the master) in times when only low power is needed to save battery range and the slave motor only turned on when the extra power is needed?


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## brian_ (Feb 7, 2017)

JeffAU said:


> With the Prius Gen 3 dual Motor set up as one set of both motors connected just running as one main motor connected to input of the original manual gearbox, and just using a lower gear to drive...


There's no reasonable way to use the Prius motors outside of the Prius transaxle (which is a power-split transmission plus final drive). The output of the transaxle is already geared to run at the speed of the wheels, so no only would you not need the original Land Rover transmission, you would have a problem with the axles providing too much gear reduction, severely limiting the speed of the vehicle. You wouldn't use a lower gear; you would need a super-overdrive.


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## JeffAU (Jul 30, 2020)

Another Idea I’ve thought of is simply using Damien’s Prius Single motor or dual motor controller board, with Prius inverter with a different 3 phase motor (or 2 smaller 3 phase motors if dual controller) other than the one out of the Prius. I guess with this there would still be need to be a master and slave?


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## JeffAU (Jul 30, 2020)

I found this video extremely informative of how the gen3 transaxle works in the Prius 






I think Damien found a way of tig welding planetary gear sets to make the whole lot turn together, so that both motors combine to run the same as one double motor. I just can’t find Damien’s article now and it might be somewhere here or on open inverter. 

Then I would imagine it would be a case of making a suitable plate to connect to the transmission bell housing, with enough precision for the existing vechicle clutch to mesh with the flywheel next to MG1 (where the damper plate was in the Prius) or for a clutchless design, still connected in this way but taking the clutch and flywheel out and replace with a flexible drive shaft (to allow for slight inaccuracies in connecting the 2 units together) I think there is a spline shaft to connect to when you remove the transaxle flywheel (from a picture I saw)


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## MattsAwesomeStuff (Aug 10, 2017)

The Weber videos are a treasure. Clear, concise, well-lit, well-shot, well-labelled, well-paced. Guy knows how to teach.

IIRC, MG1 normally runs in reverse, and is fed by the engine.

You have 2 choices, you can cut off a stub of the engine shaft and weld it in place, or, you can weld the planetary gears. If you do the former, MG1 will run at 2.5x the speed of MG2 I think, and it will overspeed. If you choose the latter, it's more difficult but it ensures MG1 and MG2 turn at the same speed, with neither running over their max speed.

The GS450H motor/gearbox is different. I believe you can weld the input spline and it works fine.


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## JeffAU (Jul 30, 2020)

I think doing the later of welding planetary gears is a better choice. Im guessing theres no reason why it can’t provide an output to gearbox by means of connecting to where the damper plate was because in the Prius, MG1 was used as a starter motor this way. It all depends if the shaft of MG1 and everything in between the MG1 and MG2, once the planetary gears are welded, are strong enough to handle MG2 driving it this way as this was not an intention in the original design. This was designed to handle the ICE driving it the other way though.


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## brian_ (Feb 7, 2017)

JeffAU said:


> ...
> Then I would imagine it would be a case of making a suitable plate to connect to the transmission bell housing, with enough precision for the existing vechicle clutch to mesh with the flywheel next to MG1 (where the damper plate was in the Prius) or for a clutchless design, still connected in this way but taking the clutch and flywheel out and replace with a flexible drive shaft (to allow for slight inaccuracies in connecting the 2 units together) I think there is a spline shaft to connect to when you remove the transaxle flywheel (from a picture I saw)


There is no clutch in a Prius or other Toyota/Lexus Hybrid Synergy Drive transmissions/transaxles.


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## brian_ (Feb 7, 2017)

JeffAU said:


> I think doing the later of welding planetary gears is a better choice. Im guessing theres no reason why it can’t provide an output to gearbox by means of connecting to where the damper plate was because in the Prius, MG1 was used as a starter motor this way.


I don't understand what you are trying to do. The engine and MG1 are connected to a planetary gearset used as a power splitter, conceptually similar to the way the left and right wheels of an axle are connected to a differential. Just like with the axle differential, if the common shaft cannot turn (in the Prius that means the car is stopped), turning MG1 turns the engine, and that's how it starts the engine.



JeffAU said:


> It all depends if the shaft of MG1 and everything in between the MG1 and MG2, once the planetary gears are welded, are strong enough to handle MG2 driving it this way as this was not an intention in the original design. This was designed to handle the ICE driving it the other way though.


MG2 drives the car by itself whenever the engine is not running - the mechanical output of MG2 doesn't go through the power splitter (the planetary gear set connecting the engine and MG1 to the rest of the system) or involve MG1 at all. I'm not suggesting this, but you could remove the entire power splitter gearset and MG1 and it would leave you with a single-motor (MG2) drive unit... although who knows what shafts would need to be left and spacers would be needed to keep the spinning bits in place.


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## brian_ (Feb 7, 2017)

MattsAwesomeStuff said:


> IIRC, MG1 normally runs in reverse, and is fed by the engine.


While the car is driving forward, MG1 can motor or generate (depending on how much torque is being transmitted) and MG1 can run forward or reverse (as required to force the engine to run at the desired speed, at the current road speed). So for instance, if you accelerate from a standstill to highway speed with constant accelerator (power), the engine will be kept at a constant speed, and MG1 will need to first turn fast in reverse (generating), then slow down, then start turning forward (as a motor).



MattsAwesomeStuff said:


> The GS450H motor/gearbox is different. I believe you can weld the input spline and it works fine.


The GS/LS/etc longitudinal transmissions are laid out differently, and have different gearing between MG2 and the output, but the power splitter arrangement (and thus MG1 operation) is functionally identical. The method for locking the power splitter may be different.


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## electro wrks (Mar 5, 2012)

"There is no clutch in a Prius or other Toyota/Lexus Hybrid Synergy Drive transmissions/transaxles."

You are right if you are referring to a typical ICE vehicle clutch. The Prius Prime (Gen 4, maybe some late Gen 3s?) I believe has a sprag clutch on the transmission input shaft. It allows both motors in the transmission to operate independently of the ICE, for more power and higher speed in EV only mode.


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## JeffAU (Jul 30, 2020)

I think what Damien has done by welding planetary gears etc. is repurposed the whole transaxle into a double motor with the equivalent of a common shaft and used his new dual motor controller kit with original prius inverters to run it like this. I have read that others are simply having a new shaft made for this altogether. I still have to look into it further but if I modify it into a double motor, particularly with a new shaft replacing all the planetary gears etc. then that part will be just like the output of any other motor. Therefore this part of the transaxle could be bolted to a plate, similar to the adapter plates that are sold for other EV motor to transmission/clutch bell housing conversions - the plate is needed because no doubt, both bell housings or holes won’t line up. A new shaft would run down the middle of both motors, connect to wherever they drive from and extend out as far as what is needed, probably past the plate, with large hole cut in the plate for flywheel from vehicle if it sits there or small hole for shaft and bearing if it is on transmission side and existing clutch goes to this. Alternatively for a clutchless design, a flexible shaft goes straight from end of shaft (modified) near MG1 to transmission input. This setup is a little bit more robust because the motor is attached by the bell housing that it has, rather than the screw holes closer to the center in most EV motors. The plate would have tapped holes to take the existing screws/bolts that were originally used to mount transmission to engine in vehicle and transaxle to ICE in Prius in thier original setups.

The whole design is dependent on:

1. weather both motors are wound to run at suitable RPM to run transmission input in this vehicle, by direct drive and provide suitable torque with Damien’s Dual Motor conversation.

2. MG1 having a large enough hole running through the middle of it to take a strong enough shaft that both, connects output to it and provides direct drive from MG2 to provide combined torque from both to transmission.

Hope this explains my idea more. I don’t have a Prius transaxle yet, but anyone who has had one apart or knows more about this, I’d be keen to hear.


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## MattsAwesomeStuff (Aug 10, 2017)

JeffAU said:


> I have read that others are simply having a new shaft made for this altogether.


I have not heard of a single person planning this.


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## brian_ (Feb 7, 2017)

Jeff, I guess I just don't understand what you are trying to build. If you are using just the motors which are in a Prius transaxle you don't need to attach the transaxle to anything else, so why are you talking about an adapter plate and a shaft sticking out? The bellhousing area would just need a dust cover over it at the most.

If you're just trying to directly link the two motors...

in the most recent transaxles this won't work - they're not placed in line with each other
even in the earlier transaxles, all you need to do is replace the power splitter with a solid piece - there's no need to go any further into the transaxle.
The descriptions and images in this article might help a bit, although they don't really describe how the parts are connected:
A technical look parallel axis hybrid transaxles


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## brian_ (Feb 7, 2017)

electro wrks said:


> "There is no clutch in a Prius or other Toyota/Lexus Hybrid Synergy Drive transmissions/transaxles."
> 
> You are right if you are referring to a typical ICE vehicle clutch. The Prius Prime (Gen 4, maybe some late Gen 3s?) I believe has a sprag clutch on the transmission input shaft. It allows both motors in the transmission to operate independently of the ICE, for more power and higher speed in EV only mode.


Good catch - thanks 

If anyone has salvaged a very recent (model year 2017+) Prius Prime (and perhaps other Prime models), they will have that one-way (sprag) clutch and thus no modification is required to use the transaxle as a two-motor EV drive unit. The clutch is integrated into the dampener assembly which is mounted to a plate between the engine and transaxle housing, so just keep that plate. This doesn't change the gearing and speed issue.









The Gen IV transaxles (apparently - according to a non-authoritative but reasonable looking description - in all cases not just Prime) have different gear ratios, which extend the possible road speed for MG1 operation higher (up to 84 MPH the the Prius tire size, from the previous 62 MPH).

So salvage a 2017+ Prime transaxle, and just use it as a two-motor drive unit. Or salvage an earlier transaxle, and mechanically lock the elements of the power splitter together.


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## JeffAU (Jul 30, 2020)

MattsAwesomeStuff said:


> I have not heard of a single person planning this.


It may have been on open inverter forum.

I have a Prius Gen3 transaxle on the way now so will soon find out.



brian_ said:


> I don't understand what you are trying to do. The engine and MG1 are connected to a planetary gearset used as a power splitter, conceptually similar to the way the left and right wheels of an axle are connected to a differential. Just like with the axle differential, if the common shaft cannot turn (in the Prius that means the car is stopped), turning MG1 turns the engine, and that's how it starts the engine.
> 
> 
> MG2 drives the car by itself whenever the engine is not running - the mechanical output of MG2 doesn't go through the power splitter (the planetary gear set connecting the engine and MG1 to the rest of the system) or involve MG1 at all. I'm not suggesting this, but you could remove the entire power splitter gearset and MG1 and it would leave you with a single-motor (MG2) drive unit... although who knows what shafts would need to be left and spacers would be needed to keep the spinning bits in place.


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## JeffAU (Jul 30, 2020)

I decided the best way to find out was to buy a used Gen3 transmission/transaxle and start with the mechanical side of it, worst case senario, if it is not possible to connect this up mechanically I will no doubt use this in another project, or for the additional front drive motor alone, that I mentioned I’m thinking of adding later, or additional front Regen braking alone, or for a separate wind turbine generator that I built later and rectify the output of one or both motors.

It only cost me $200 AU, and I’ve seen matching inverters for $200 as well, this is about one fifth of the price of the same parts from any other car here in Australia because of the amount of Priuses having been used for taxis here for many years, and the ex-taxi mileage factor doesn’t really matter for these parts - I don’t think mine is from a taxi though as there is a picture of the original wreck it’s from. 

It’s probably time for me to start a new thread about my project when I start this because my plan has changed so much since the beginning of this thread - will keep you posted when I get this transaxle apart and work out what I’m doing.


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