Thought we would share our progress converting a 2003 Mini-Cooper S to an EV. My sons and I started this effort in April 2009 with purchase of the donor car followed by the VFD, Batteries, and AC motor. We are still in the prototyping phase. We recently drove the car and have learned the limitations of our Industrial VFD.
Donor Car: 2003 Mini Cooper S w/o Engine and Drive Tran
Motor: Ford F8Y8-14B280-AC (Siemens PV5133-4WS20 W11)
Motor Control: BENSHAW 100 HP VFD
Battery: Two custom packs made of 42 Prius Battery Modules
If you mean a burn out, then no. We threw it together to try it before winter hits and did not torque the coupler properly yet. We need to disassemble to change out the non-lubricated bearings in the motor, wanted to make sure we could get it off. We did manage to spin the tires pulling up our drive way because of its angle. We have a video of that, but I was not able to upload to anywhere yet -- I am not that knowledgeable in that area. I hope to put a link to the video of Mini on road with some help from my son.
I have not added all the costs up. Here is a breakdown of the major components. We don’t have a battery charger yet. I plan to modify a power supply for this.
Mini $3,400 + $700 shipping Motor: $1,590 VFD: $ 990 Transmission: $1,700 Three Prius Battery Packs: $1,467 Misc. est. $1,400
Thanks !! . I don't have a thread or a web page. I hope to get some help from my sons getting something setup over the Chrismas Holidays, when we have some time.
Are you running the prius pack as one high voltage pack or two parallel packs? I am working on the same type of thing. Experimenting right now. My pack is a low voltage pack. Much harder to do. How do you like the Prius batteries? How's the charging? BMS? What is your running voltage?
Are you running the prius pack as one high voltage pack or two parallel packs? I am working on the same type of thing. Experimenting right now. My pack is a low voltage pack. Much harder to do. How do you like the Prius batteries? How's the charging? BMS? What is your running voltage?
We are running two battery packs of 42 series modules in parallel (best case 13 amp-hr). I hope just enough to get me to work and back daily. I wanted to run all in series so we would not need to modify the controller we have -- not sure what effect the modifications have had on its overall performance. I was not able to get any answers on the dielectric operating voltage of the motor, so we went with the lower voltage.
For test runs we are not fully charging or discharging (we think) the battery pack. Only charging the battery pack at 5 amps for now. We don’t have a battery fan or BMS setup yet. Have been charging the pack to 357 volts (42 x 8.5).
The Prius battery modules are nice to work with from a packaging and flexibility point of view. You must keep a close eye on the temperature of the battery modules when charging to get a full charge. We put one pack in what looked like thermal runaway before we got smarter about charging. It took two large fans more than an hour to get it back to room temperature.
We have put up a web site http://www.bmpenterprises.net/ to caputure this and possible future projects. Below is the post on how we made the Mini-EV version of a Tischer style coupler. I could not include all the pictures here so if you want to see more please look at the web site.
The following shows the basic steps used to fabricate the Motor to Transmisson Coupler. This coupler used concepts shown by Tischer.
Testing fit of B-lock on Centering Plug:
Not shown here but we clamped on the B-Lock and drilled pilot holes using B-Lock as guide by removing and replacing each B-Lock screws one by one to drill the holes shown:
Its tough, but Adam lets it know who’s the boss:
Transmission Spline Coupler is cut loose. Note, the circular step bushing on the back we can use to center this piece to the coupler.
Test fit of Transmission Spline Coupler to its centering hole:
Boring out motor shaft clearance hole:
Used previously drilled pilot holes to center and drill each hole through aluminum spacer. Then we bolted on the Transmission Spline Coupler to match drill the bolt and locating pin holes:
These are the steps we used to create the adapter plate to attach and center properly the motor to the transmission.
We started with a 3/4" 6061 aluminum plate and made an acrylic template that showed the bolt holes from both transmission and motor as well as the outlines. This kept us on track and helped make decisions.
The next step was to drill holes for the alignment pins in the transmission. We marked the two spots using the transmission as a guide.
The use of transfer punches made sure the plate was marked properly.
Here are the finished holes with threads, looks like we selected the correct bolt lengths.
From there we needed to find the exact center of the transmission to later line up with the exact center of the motor. To do this we created a 'center punch' that we fitted onto the transmission shaft and used the clutch action to make our mark.
At this point we didn't have the capability for precise machining on a piece of this size. So we hired a machinist to cut our centering ring and the hole for the coupler. Here it is back from the machine shop.
And then the first complete fitting test between motor and transmission.
Then we began the process of marking the bolt holes for the motor using a transfer screw set, shown above. http://bmpenterprises.net/blog/wp-content/uploads/2009/12/IMG_0600.jpg
After drilling and testing all the holes they needed to be countersunk so the transmission could sit flush against the plate.
The last modification to the plate was to make room for the trans-axle on that side. So we cut a radius by drilling several holes and cutting out with a saw.
This post contains a breif overview of what we learned trying to use an Industrial VFD as the Motor Controller.
If any one has some ideas or experience on how to overcome the issues associated with the transition from Coast to Stop, to Run, and then to Flying Start discussed below I would appriciate the help.
We purchased two used Industrial Variable Frequency Drives on eBay. The first one was a 30 HP 460 AC Benshaw Sensorless Vector Drive RSi030SX4B which turned out not have enough current output to get the car rolling consistently from a dead stop without tripping the hardware over-current protection circuit (~80 Amp). We were able to drive the car, once the car started rolling. It just could not supply enough current to move the car without tripping the hardware protection limit. The second one which we are using now is a 100 HP 460VAC Benshaw Sensorless Vector Drive RSi100SG-4B (~150 Amp).
If you are planning to try to use an Industrial Motor Control in your electric vehicle project here are some lessons learned:
Most units above 30 HP are only available in the higher 460 VAC. Unless you plan to run a 600 VDC system you will need to modify the unit to operate at a lower voltage.
Make sure it has a sensorless vector torque producing mode of operation, or you will need an external shaft position sensor to get high torque at low speeds.
Make sure the maximum AC frequency output of the controller is known and is high enough to support the the max motor rpm desired. The 100 HP unit we have is limited to 120 hz which sets our max to 2500 rpms, 40 mph in second gear. To get more out of our motor, it should be more like 300 Hz.
Make sure the controller has the ability to turn off the phase loss detection. If not you will need to "fake out" the detection circuits.
Make sure that it has a control mode which lets you command an output torque not speed. Our present controller only lets us command a target motor speed with timed speed ramps which results in difficult operating conditions when stopping.
If the controller does not have a command torque mode, it needs to have someway to associate an external switch input to the "COAST TO STOP/RUN control input to turn off the drive output when coming to a stop if you do not have a clutch. This input is needed to circumvent the controller speed control loop which is trying to hold the rpm at the commanded speed.
If the controller does not have a commanded torque mode it needs a "flying start" mode which keeps the the Controller's output current low until the motor and commanded rpm are the same. Unfortunately our experience to date is that this does not work well in our electric vehicle application and is the only reason we cannot drive the car around town safely. If "flying start" mode does not work well, the only way to accelerate after a "COAST TO STOP/RUN" command is issued, is to come to a complete stop, and then accelerate. The alternative to a full stop and then start is a screaming controller and a bucking car while the controller tries to sync the speed. This does not work in traffic.
I was a VFD Applications Specialist for Square D for a number of years. I’m new to the EV world and was wondering if someone had tried to adapt an AC VFD to the EV world. I’m assuming you bypassed the front-end AC/DC converter and tied into the DC/Capacitor part of the drive. Seems like one thing you discovered is that AC VFD’s, though are listed by H.P., are actually current rated devices. The Benshaw unit you listed is rated at 152A’s when set up in Variable Torque load. When set up in what Benshaw refers to as “Heavy Duty” ( other mfr’s label this as constant torque) this is reduced to 111A’s. What this really means is that VFD will allow the current draw to be 166-167 FLA’s for 1 minute before it kicks of on “Over-current”. This is all based on AC motor current draw of a 100 hp AC motor drawing about 124FLA’s @ 460V’s. One requirement of an AC VFD is to limit the current inrush associated with the AC motor. An across-the-line start can be 6-10 times the current full-load draw.
The first/most critical parameter to set/understand is the Ramp/Up Ramp down time. Sq. D’s out of box was set at 3 seconds. I’m not familiar with the Benshaw, but most/all VFD’s have different torque profile’s. Most common is a linear, but there are typically modes like “Torque Boost” which can be tried. The reason I bring this up is that it appears the biggest issue you seem to be having is with the “Flying Start” parameter….Also known as a “Catch-on-the-Fly” parameter by other Mfr’s. What actually happens is that in the sensorless flux vector setting the VFD is looking at FREQUENCY the motor is running at, then induce more Hz back into the motor to accelerate the motor back up to the desired/set speed. Speed control on the VFD is usually achieved by a potentiometer wired into the VFD. If you go 0-100% on the pot and the ramp-up/ramp-down will follow the ramp speed you have set. IE: if you “floor” your EV it will allow current to flow to 100% whatever the ramp time is…same with ramp down/decel. Now when you get back on the “gas” while the EV is coasting you are trying to utilize the “flying start” and “coast to stop” parameters, but with the ramp times being a part of the speed control loop algorithm you are starting and stopping faster then what the algorithm is set to run. Have you played with the ramp times?
I was a VFD Applications Specialist for Square D for a number of years. I’m new to the EV world and was wondering if someone had tried to adapt an AC VFD to the EV world. I’m assuming you bypassed the front-end AC/DC converter and tied into the DC/Capacitor part of the drive. Seems like one thing you discovered is that AC VFD’s, though are listed by H.P., are actually current rated devices. The Benshaw unit you listed is rated at 152A’s when set up in Variable Torque load. When set up in what Benshaw refers to as “Heavy Duty” ( other mfr’s label this as constant torque) this is reduced to 111A’s. What this really means is that VFD will allow the current draw to be 166-167 FLA’s for 1 minute before it kicks of on “Over-current”. This is all based on AC motor current draw of a 100 hp AC motor drawing about 124FLA’s @ 460V’s. One requirement of an AC VFD is to limit the current inrush associated with the AC motor. An across-the-line start can be 6-10 times the current full-load draw.
The first/most critical parameter to set/understand is the Ramp/Up Ramp down time. Sq. D’s out of box was set at 3 seconds. I’m not familiar with the Benshaw, but most/all VFD’s have different torque profile’s. Most common is a linear, but there are typically modes like “Torque Boost” which can be tried. The reason I bring this up is that it appears the biggest issue you seem to be having is with the “Flying Start” parameter….Also known as a “Catch-on-the-Fly” parameter by other Mfr’s. What actually happens is that in the sensorless flux vector setting the VFD is looking at FREQUENCY the motor is running at, then induce more Hz back into the motor to accelerate the motor back up to the desired/set speed. Speed control on the VFD is usually achieved by a potentiometer wired into the VFD. If you go 0-100% on the pot and the ramp-up/ramp-down will follow the ramp speed you have set. IE: if you “floor” your EV it will allow current to flow to 100% whatever the ramp time is…same with ramp down/decel. Now when you get back on the “gas” while the EV is coasting you are trying to utilize the “flying start” and “coast to stop” parameters, but with the ramp times being a part of the speed control loop algorithm you are starting and stopping faster then what the algorithm is set to run. Have you played with the ramp times?
Thanks !! for reading and trying to help. I had hoped to put more info up on how we modified the drive but other things are too demanding right now. To get the drive to operate at the lower voltage we shorted out and trimmed some of the input voltage sense resistors and startup resistors on the auxiliary power supplies.
You are correct, we bypassed the AC/DC front end and tied into the DC Capacitor bus. We are using a pre-charge resistor before applying battery to prevent inrush.
We learned quickly we had to set the ramp down time much longer than the ramp up time or our heads might come off when you let off the accelerator peddle. We learned the hard way how well Regen in an AC Induction motor can work. The drive I have unfortunately does not have a parameter to adjust Regen current level. In Regen, it only halts deceleration based on the sensed input voltage increase which is not useful because that is basically held fixed by the battery. Have thought about using the future battery current sense circuit to offset the input voltage sense.
Last time we drove the Mini we had the ramp up time set for 5 seconds and the ramp down at 15 seconds. The 15 seconds avoids the head snapping and helps keep the Regen current to battery low. I have not investigated the relationship between the ramp times and the “flying start”. I was wondering if the issue was related to my inability to hold the throttle peddle still while the drive tries to sync up the frequency. I would like to think the drive would quickly sync up and then apply power to ramp like normal to whatever the set point was. It seems the ramp times and power should be off until it has synchronized. It acts like its driving current while its searching. I wondered if it is turning on the boost current during this time or some brake current. There is another mode “Delta Freq” I have not investigated to see if it would help here. In the “Delta Freq” mode the Accel/Decel time is the time that takes to reach a target frequency from any frequency. I tried this mode early on to try to address accelerator response. I did not like the results at the time. Do you think this mode would help with this issue?
Please keep in mind I’m new to the EV world, but do know the Industrial VFD world. Trust me; I’m learning more from you and the other members on this forum then I will ever be able to give back. Don’t know your background, but it sounds like you really understand the electronics’ part of the drive (board-level if you will) better then me. One thing that might help you is to remember what the original intent of the VFD mfr. was/is. You’ve run into the regen braking capability built into even a sensorless flux vector drive. In your research you probably ran into full flux vector drives with encoder/resolver feed-backs. Suffice it to say a VFD can be used in indexing machine’s such as Hass CNC machines. The VFD will inject DC back into the motor to stop it as fast as you want…the one thing required is a (dynamic braking) resistor bank to allow the current to bleed off somewhere. These are available from a number of sources, but I have a feeling you know enough you might want to “roll your own”. This function, however, is utilized more in position control applications (CNC machines) and with my limited knowledge of EV’s I didn’t think this was something that would come into play in the EV world. On the decel side of things I would have thought that you would set the “Free-Wheel” stop parameter set which should effectively ignore the “ramp-down” time and not try to slow the motor down. Sounds like you tried this already, but maybe the motor on decel is generating enough current that is having a hard time trying to dissipate. Just a thought.
I don’t think your inability to hold constant the throttle pedal constant but you didn’t mention what you are using to control the speed. Don’t have a Benshaw manual handy, but it typically is a 10K pot. If your ramp up time is set at 5 seconds and you crank the pot to 100% the current flow should be linear over the 5 second ramp. If the linear ramp doesn’t suit the application there is typically other parameters that allow for voltage boost or other high enertia start applications to boost torque to the motor. These all work a little different from mfr. to mfr. Heavy flywheel’s, loaded conveyor system’s, etc. (EV’s) are the sort of applications the mfr’s. had in mind and they consider these to be constant torque (heavy duty in Benshaw language). The (potential) problem with setting your specific Benshaw VFD to “heavy duty” is that it is going to drop the FLA’s it bases everything on from 151 amps to 111 amps…probably not the direction you want to go.
The “Delta Freq” parameter I’m not positive as this sounds like Benshaw vernacular, but I’m fairly certain that this is more for set-point applications. An example is on a machine tool where there is a cutting speed at a specific rpm/frequency and then needs to jump to a different specific rpm/frequency. Doesn’t seem to be a parameter applicable to what you are trying to accomplish.
Please keep in mind I’m new to the EV world, but do know the Industrial VFD world. Trust me; I’m learning more from you and the other members on this forum then I will ever be able to give back. Don’t know your background, but it sounds like you really understand the electronics’ part of the drive (board-level if you will) better then me. One thing that might help you is to remember what the original intent of the VFD mfr. was/is. You’ve run into the regen braking capability built into even a sensorless flux vector drive. In your research you probably ran into full flux vector drives with encoder/resolver feed-backs. Suffice it to say a VFD can be used in indexing machine’s such as Hass CNC machines. The VFD will inject DC back into the motor to stop it as fast as you want…the one thing required is a (dynamic braking) resistor bank to allow the current to bleed off somewhere. These are available from a number of sources, but I have a feeling you know enough you might want to “roll your own”. This function, however, is utilized more in position control applications (CNC machines) and with my limited knowledge of EV’s I didn’t think this was something that would come into play in the EV world. On the decel side of things I would have thought that you would set the “Free-Wheel” stop parameter set which should effectively ignore the “ramp-down” time and not try to slow the motor down. Sounds like you tried this already, but maybe the motor on decel is generating enough current that is having a hard time trying to dissipate. Just a thought.
I don’t think your inability to hold constant the throttle pedal constant but you didn’t mention what you are using to control the speed. Don’t have a Benshaw manual handy, but it typically is a 10K pot. If your ramp up time is set at 5 seconds and you crank the pot to 100% the current flow should be linear over the 5 second ramp. If the linear ramp doesn’t suit the application there is typically other parameters that allow for voltage boost or other high enertia start applications to boost torque to the motor. These all work a little different from mfr. to mfr. Heavy flywheel’s, loaded conveyor system’s, etc. (EV’s) are the sort of applications the mfr’s. had in mind and they consider these to be constant torque (heavy duty in Benshaw language). The (potential) problem with setting your specific Benshaw VFD to “heavy duty” is that it is going to drop the FLA’s it bases everything on from 151 amps to 111 amps…probably not the direction you want to go.
The “Delta Freq” parameter I’m not positive as this sounds like Benshaw vernacular, but I’m fairly certain that this is more for set-point applications. An example is on a machine tool where there is a cutting speed at a specific rpm/frequency and then needs to jump to a different specific rpm/frequency. Doesn’t seem to be a parameter applicable to what you are trying to accomplish.
My background is electrical engineering, I graduated from Purdue in 1974. I am one of those old analog circuit type guys with some early career background in switch mode power converters. Back when 10KHz switching was fast and the first 1524 came out. Three of my four sons and I were members of a High School Solar car team which won the World Wide Winston Solar Car competition. So I can’t say I am a newbee to EVs, but I am to AC Induction Motors and especially VF AC Drives. One of the main purposes of this build project was to educate myself and my youngest son in this area and plug in cars. I can say I have learned a bunch the last few months, but I am not an expert and appreciate your help and suggestions.
I am using the Benshaw "COAST TO STOP/RUN control input to turn off the drive output when coming to a stop, I assume this is the same as “Free-Wheel” stop. I only want to use “Free-Wheel” stop when I use the mechanical brake. That way I can recover some energy back into the battery when slowing down before I put the brake on. The problem is under typical driving conditions one puts on the mechanical brake several times, like when someone slows quickly in front of you. Under this condition you don’t come to full stop and you want to go again. My issue is I have not found a configuration of functions where the motor smoothly recover to free wheeling motor rpm so I can reaccelerate. I think getting the “Flying Start” function to work is my last hope. I have not played extensity with the gain and integral setting provided for this function, but initial attempts did not seem to help. I have done my best to ensure the DC brake function and the like are off. But suggest anything that comes to your mind because again I am no expert either and I could have over looked something.
The Mini has what I think is a HALL position sensor on the throttle peddle that takes 5 volts and puts out a voltage proportional to the position. I added a regulator to the Benshaw sensor supply to provide 5 volts and ground and feed the signal into the A/D input and programmed the speed command to use the A/D channel and not key pad input. Then used program functions to set gain and offset to get full frequency range.
PS. If you have an interest or think your High School would be interested in starting a Solar Car project go to this link http://www.winstonsolar.org/challenge/photos/2003/Day1/Originals/day1_12.jpg This was the last car we raced. The process to raise funds, plan, build and then race a car against your peers is a great learning experience for kids. Our car was called Solar Stealth. We raced 1997 to 2003.
Wow, not sure how I missed this thread. You have accomplished alot in 9 months, and thanks for posting.
Sounds like you are going through the same learning process I went though with my conversion. I too started out in a v/hz speed mode. Is your inverter capable of Sensorless vector?
Wow, not sure how I missed this thread. You have accomplished alot in 9 months, and thanks for posting.
Sounds like you are going through the same learning process I went though with my conversion. I too started out in a v/hz speed mode. Is your inverter capable of Sensorless vector?
Thanks !! As you see I relied heavily on your coupler concept. And would be nowhere as far along without that prior knowledge.
I hoped you might see post and provide some insight into this VFD issue. Although, somewhere I got the impression your base control unit might have a commanded torque output mode. Dead End Kid is correct. The Benshaw drive I have is sensorless vector control type. It has ability to run V/F mode. I never tried running in V/F mode in the 100 HP drive because my initial attempts running the motor using the lower HP drive never were as good as vector control. I think its partly because I did not know what V/F ratio to program in and the vector control took care of that for me.
Sorry...not trying to answer for zaxxon, but being the new excited guy, I just quickly went thru your build. The Benshaw VFD zaxxon is using is a current sensorless flux vector drive. Looks like you are utilizing a loop feed-back resolver/encoder approach. One of the suggestions I was going to make to zaxxon was to put his drive in a volts/hz mode to do the preliminary tuning and familiarization, then switch back to the flux vector control. I think you can do that with the Benshaw unit.You probably have very valuable input for that approach.
Foot off throttle: Speed set point = 0 rpm
Foot on throttle: Speed set point = 8500 rpm
accel & decel ramp = 0.1 seconds
Throttle position 0->100% = Torque set point 0->150%
Even though the speed set point is 8500 rpm, you are limiting torque, so the motor will only spin as fast as the torque demanded will allow it to spin. (you may need to disable speed error alarms)
If you want a bit of regen drag when off the throttle then
Throttle position 0->100% = Torque set point -10% -> 150%
When I hit the brake pedal, Torque set point goes to -50%
When braking, once battery voltage reaches 350 volts, for every volt above 350, I reduce regen torque limit by 5%. This gracefully prevents the bus voltage from going too high.
When I was running v/hz mode, I too tried to catch a spinning motor. On my inverter it was called "fly catching". I couldn't ever get it to work properly. I also tried ramping stop instead of coasting stop. I kept a speed pot on my lap to control the speed of the car. The major down side is the inverter wants to follow a ramp down which may significantly increase your stopping distance, and if you ramp down too fast you will either over current, over voltage, or loose synch and start bucking.
You really need to get torque control working to make the car drivable. Older drives may have a torque control mode, but often times at low rpm it is still using v/hz mode with dc boost. Does your inverter have an auto tune?
Foot off throttle: Speed set point = 0 rpm
Foot on throttle: Speed set point = 8500 rpm
accel & decel ramp = 0.1 seconds
Throttle position 0->100% = Torque set point 0->150%
Even though the speed set point is 8500 rpm, you are limiting torque, so the motor will only spin as fast as the torque demanded will allow it to spin. (you may need to disable speed error alarms)
If you want a bit of regen drag when off the throttle then
Throttle position 0->100% = Torque set point -10% -> 150%
When I hit the brake pedal, Torque set point goes to -50%
When braking, once battery voltage reaches 350 volts, for every volt above 350, I reduce regen torque limit by 5%. This gracefully prevents the bus voltage from going too high.
When I was running v/hz mode, I too tried to catch a spinning motor. On my inverter it was called "fly catching". I couldn't ever get it to work properly. I also tried ramping stop instead of coasting stop. I kept a speed pot on my lap to control the speed of the car. The major down side is the inverter wants to follow a ramp down which may significantly increase your stopping distance, and if you ramp down too fast you will either over current, over voltage, or loose synch and start bucking.
You really need to get torque control working to make the car drivable. Older drives may have a torque control mode, but often times at low rpm it is still using v/hz mode with dc boost. Does your inverter have an auto tune?
The drive I have does not have a torque command mode from what I can determine. I have read about drives that do like the Allen Bradly enhanced 70EC version that has it and the Standard non-EC does not.
These are the only control mode settings I have. The commanded input only sets a speed target for these modes.
Does your drive's firmware have a specific control mode called torque control mode where the set point can be torque and not speed? By your discription above sounds like yours might have a speed set with independent torque limit control setting?
The drive I have has auto tune and I have used it.
My inverter has a speed set point, and also a torque set point.
Torque is directly related to Slip speed.
Slip speed = Commanded speed - Actual speed.
If speed control is your only option, you could possibly get a torque control mode working with some external controls.
I wonder if the siemens motor could be re-configured for 460v operation. This would match it better to your 100hp inverter. I know there are other Siemens motors in this size that are 460v, it may not take much to switch the voltage.
My inverter has a speed set point, and also a torque set point.
Torque is directly related to Slip speed.
Slip speed = Commanded speed - Actual speed.
If speed control is your only option, you could possibly get a torque control mode working with some external controls.
I wonder if the siemens motor could be re-configured for 460v operation. This would match it better to your 100hp inverter. I know there are other Siemens motors in this size that are 460v, it may not take much to switch the voltage.
I have thought about trying to use the drive’s “external the PID” loop to attempt to control torque by using a current sensor feedback to control speed/slip. Then I thought, better to just go buy a low cost drive with torque control features similar to what you did and perform a lobotomy on the drive. It seems they are not that easy to find at a reasonable price.
We need a low hp AC drive for future use to drive the Prius electric AC compressor we purchased. So I have been keeping watch for a cheap one. Saw a newer Allen Bradley 3hp PowerFlex 70 come up on eBay. I checked the manual on line before bidding and it implied it had torque control so I took a chance and got it. I should have read the fine print in the foot notes. As it turned out that feature is only available for the “enhanced EC” version. I found on the AB forum one response from AB that said the model 70 requires additional hardware and cannot be flashed to get the new enhanced features. I was lucky, I only paid $50 for it and it works fine just no torque set mode. I am still hopeful I can use for Prius compressor, but according to some things I read about the Prius compressor implied you need more like a 5 hp. Someday in the distant future we will find out.
Not sure about rewiring the motor for higher voltage. Unless it is tapped internally for that, and I am no expert here, it would require a total rewind which I would guess in very costly unless you DIY. Also I never was able to get a good answer on the dielectric rating on the motor windings. I have read enough articles on the dielectric breakdown in pulsed motors to be very concerned about it. With the wrong kind of wire, the time to punch through decreases rapidly from years to days to hours as the voltage goes up. Output filters can be added to cut down on the really high voltage spikes, but I would guess impractical to filter all the way back to a nice voltage sine wave. So the windings see nearly the full switched line voltage under all operating conditions.
I could be wrong here, but I think under vector control, the voltage is not a key factor except for the resulting pulse width to get the current wave to satisfy the speed/torque loop. So I think the input voltage sense alteration we did to the drive is not a factor. Except I have concerns the modification might effect the auto tune function. The magnetizing current it defaulted to based on hp also looked way to high so we took a guess and set lower – I don’t recall the value 17A ? I don’t think this initial value matters that much in vector control mode. There is indication that the Benshaw drive is monitoring the output voltage. I hope it is using that for auto tune. I thought I wrote them down, I think they were around 50 milliohms and 900 microhenry. How do these compare to your measured values? I just realized you probably were suggesting the rewire so I would have more power because of my lower currents. Right now the car seems have enough hp for my planned drive to and from work. I would like to upgrade in the future.
I have been reading and researching components and I am almost convinced I might have enough skill to attempt to marry one of the many available micro controllers out there with there available source code to the power section we have. Then we would have full control to do what we might need to expand box to box communications and replace the power section in the future. But I am not so naïve to think this would be easy because I have limited experience programming/modifying code and other time demands, and my youngest son recently started full time employment. In fact, although it’s Saturday, I should be working on my direct reports performance summaries right now - don’t tell my boss.
The auto tune numbers won't mean anything from my inverter cause the inverter still thinks a 2hp motor is connected.
My magnetizing current is 105A. Typically this is some fraction of FLA. Magnetizing current is flowing though the motor windings, and though the IGBT's (via fly back diode) and isn't used for producing torque. Since Mag is mostly circulating, it doesn't take much battery current to keep it going. Was your 17A from the battery, or at the motor?
The auto tune numbers won't mean anything from my inverter cause the inverter still thinks a 2hp motor is connected.
My magnetizing current is 105A. Typically this is some fraction of FLA. Magnetizing current is flowing though the motor windings, and though the IGBT's (via fly back diode) and isn't used for producing torque. Since Mag is mostly circulating, it doesn't take much battery current to keep it going. Was your 17A from the battery, or at the motor?
The value is the displayed drive output current. What I recall, the value I programmed into the “Noload – Curr” on the 100 hp drive matched with the displayed output current shown when motor was put in Run. The 100 hp unit set a default value based on the motor hp entered. I don’t recall the number it placed, but it was much higher than the actual no load current we saw when running with the lower hp vector control drive. So I used the lower value since I want to use as little power as possible.
I found instructions below pulled this from a Siemens MicroMaster Manual. Until I remove the motor again, I can only run transmission in neutral which is probably good enough. Its cold now so maybe this spring. It would be interesting to see how your neutral output current compares to the lower value or 100 amps at low speed. I guess one would need to lower the programmed value first and then run motor. The procedure does not say that.
Siemens MicroMaster Manual says: In order to determine the magnetizing current (P0320/r0331), the motor should be accelerated up to approximately 80% of its rated speed under no-load operating conditions. In so doing, the following conditions must be carefully maintained: − the vector control must be activated, P1300 = 20.21 − no field weakening (r0056.8 = 0) − flux setpoint, r1598 = 100 % − no efficiency optimization, P1580 = 0 % No-load operation means that the motor is operated without a load (i.e. no coupled driven machine). Under steady-state conditions, a current r0027 (Act. current) is obtained that approximately corresponds to the rated magnetizing current r0331. (the current is always less than the no-load current for a pure V/f control).
I thought you may not have looked at all the pages yet. My oldest son had bought the lathe at an action a few years back. I thought it would be a good project for us to learn how to use it.
Thanks for asking. Not much to report. I am still looking at options to build a drive with a microcontroller kit while keeping a look out for a used drive with torque control and other parts.
It’s been a struggle to find a good combination of IGBT configurations and the needed driver circuits at an affordable cost and reasonable lead time. I bought some ebay 400A 600V dual IGBT PRX CM400DU-12F for $48 each recently to build an output stage. I should have researched them more first. Learned F type require a special driver circuit to work with the internal current sensor drive clamp. Also these are no longer recommended for new designs. It’s been difficult to find the required/desired drivers actually in stock. Told 26 wk lead time. Ordered from one company who claimed they had, turned out they only had four, and said their techs had pulled others, but did not record. Found more, they required a minimum buy of five which is all they had.
Recently got quotes for liquid cooled cold plates. Looks like I will have to pay $350. Thought I should be able to get for under $250.
Also been trying hard to locate a sealed or shielded hybrid (ceramic balls) or insulated bearings for the motor. I am learning the hybrid bearings in this size are rare and are very expensive. Found the sealed bearings are limited to 5000 rpm. We still need to pull the motor out and replace the original bearings. Looked like you bought the higher speed shielded bearings. Do you know if the original were ceramic or insulated to prevent circulating currents?
Saw where you installed your new batteries. Looked good.
Zaxxon, if you get it wrong, it can bite you in the tail. However, I have been working with industrial drives for more than 20 years, and I have only one motor that had problems with pitting in the bearings. Replaced the bearings, cables and fixed the earthing. I think we had to pull the motor last year because the bearings were shot because they put cheapies in the motor - it pull a flywheel in an 700 ton press, about 120kw - and they collapsed due to the sideload. Hopefully, decent (normal, heavyduty) bearings has cured it. Long cable lengths are a significantly bigger problem in industry, and also contribute to the problem of circulating current, but NO Ev is going to see 100 feet of cable .
This is also one of those problems that has slowly disappeared as technology matured, so unless you wish to used 20+ year old technology, it is not really a concern.
Wow! an AC system and some seriously smart design!
That is absolutely beautiful! And I do mean beautiful!
Prius packs... hmmm... that is totally do-able!
Wow! an AC system and some seriously smart design!
That is absolutely beautiful! And I do mean beautiful!
Prius packs... hmmm... that is totally do-able!
Thanks !! I don’t have long term experience with the Prius batteries yet. Given we got the batteries from three eBay locations and the batteries were built different years. And after crudely charging and running a couple of times and sitting without charge over the winter outside, that the two disconnected series packs measure within 0.5 volts says allot for their quality.
Unfortunately not allot of real useful progress. Investigated a Mircohip processor driving a Prius Inverter power stage. Was able to drive the Mini a couple of blocks in open-loop v/f and not as far in sensorless closed-loop. Can't get up my driveway. The closed-loop vector control has proven very difficult given the Microchip application note documentation and my limited software and microcode knowledge. Things are just not working the way they should. Lot of current going in, not much torque coming out. There are several unknowns which could be the root cause, but I am close to concluding the major problem is that the Prius Inverter maximum output current (~200 amp peak per phase) is just not enough to effectively move and accelerate the car without hitting the current limit. On the other hand I also can’t seem to get a reasonable high current waveform shape at low frequencies which may be the problem. I started playing with the Prius inverter because it had everything I was looking for: motor inverter, nice compact package and water cooled. It also has inverter for air conditioner and a dc to dc converter all in same package if I could just get these all to operate.
I just discovered this thread and I am impressed by how much you have accomplished. I too have one of the Siemens/Ford motors and am slooooowly converting a Mazda Miata. The other area of common interest regards the user of a Prius A/C compressor.
I have succeeded in getting my compressor to run at part speed by adapting a TI/Luminary Micro BLDC development board. These board are available for $100-150, I paid more because I bought the development kit about a year ago.
To this point I have only modified the software for the TI board and I have the compressor running at a maximum of ~2500 rpm. The limitation is caused by the back EMF, of the compressor’s motor at this speed, as it approaches the maximum voltage limit for the board. I am actually pushing the board to 48 vdc after studying the individual component’s absolute maximum ratings.
I plan to graft on a higher voltage output stage if the A/C cooling output proves to be inadequate. I have the compressor fully plumbed into the Miata and get abundant cold air. Since the Miata’s passenger compartment is so small I may be ok as-is. I can produce about 30 degree F temperature drop below ambient at the cold air output ducts.
The software mods are primarily related to controlling the motor drive and interfacing to the signals from the Miata. I have also spent some time (mostly trial and error) setting the drives parameters to work with the compressor’s motor. The sample code from TI is a decent starting point but I had to eventually get a compiler running to get it to do what I wanted.
If any of this would be helpful to you I am glad to share what I have.
I just discovered this thread and I am impressed by how much you have accomplished. I too have one of the Siemens/Ford motors and am slooooowly converting a Mazda Miata. The other area of common interest regards the user of a Prius A/C compressor.
Thanks for the offer. I have a 2HP Industrial controller I was planning to adapt to run off the main battery pack. My battery pack is only 13 AH so until I can upgrade, I will be without air conditioning and power steering.
Did you go with a commercial controller for the Ford motor? Or is that an open item for you too?
Given the recent discussions on the use of Prius Inverter, I said I would put up some pictures on my efforts.
Removed the link capacitor to see the driver circuit and replaced it with a smaller cap (blue) and hooked 36 volts across it. Using the setup below, hooked 12 volts between connector labels IGCT and GINV to power up the control logic and IGBT isolated drivers. Determined a low input on the Motor phase control signals (MWU, MVU, MUU) turned on the upper IGBT and a high signal turned on the low side IGBT. The control lines are pulled up to 12 volts. The switch point going low is around 6.8 volts and going high is 8 volts.
Some initial testing with the microchip development board.
Removed the Boost converter components to make room for the future control circuits.
Cleaned out heat sink compound and put link cap back in. Also put back the original harness to the inverter control board once I determined that I could alter one of the Prius Battery connectors and use it to bring out the connections I needed.
Made up harness to connect to the Microchip board, bottom of picture, and install inverter unit in car.
Using external current sensors that are centered at 2.5 volts which make it easier to interface to the microchip board. Planning to use the inverter's built-in current sensor which are centerd at zero and go plus and minus voltage in the future. One of the recent issues was that the external current sensors were saturating at 200 amps messing up the current loops.
In November charged up the batteries to try out higher current sensors. Was able to set higher control currents, but still have signifcant control issues just before coming to a stop and still requires too much magnetization current to move the car resulting in Prius inverter overcurrent trips.
In November charged up the batteries to try out higher current sensors. Was able to set higher control currents, but still have signifcant control issues just before coming to a stop and still requires too much magnetization current to move the car resulting in Prius inverter overcurrent trips.
I haven't bought batteries yet nor a charger. Do you think that the boost circuit you removed from the inverter and the MG1 current sensors that are not used possibly make a good battery charging solution? I am picturing reversing the boost circuit input and output wiring so it could be modulated to boost the line voltage higher than the battery voltage and use the current sensor to control a charging profile.
I need to learn more about battery charging in general but I was thinking this would be a nice use of all the components and still take advantage of the prius cooling plate. I am always thinking of ways to save money and this looks like a possible way.
I am going to try something like this using the MG1 switches since I don't have a boost circuit on my inverter. You may have more luck with it. Let me know if you think this would work or if you are going to try it.
I haven't bought batteries yet nor a charger. Do you think that the boost circuit you removed from the inverter and the MG1 current sensors that are not used possibly make a good battery charging solution? I am picturing reversing the boost circuit input and output wiring so it could be modulated to boost the line voltage higher than the battery voltage and use the current sensor to control a charging profile.
I need to learn more about battery charging in general but I was thinking this would be a nice use of all the components and still take advantage of the prius cooling plate. I am always thinking of ways to save money and this looks like a possible way.
I am going to try something like this using the MG1 switches since I don't have a boost circuit on my inverter. You may have more luck with it. Let me know if you think this would work or if you are going to try it.
For now planning to modify a Vicor Power Supply for the battery charger unless I run across a much lower cost charger. It would be nice to use the second inverter stage for something. It seems it should be possible to use it along with some inductors and control circuits to build an AC to DC boost converter.
I am not sure I follow why you suggested reversing the input and output of the boost circuit. If it’s an ordinary boost converter (might be bi-directional buck-boost), I think one could use it as wired by supplying rectified and filtered 110 VAC at the battery input terminals and the battery hooked on the inverter stage side.
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