Prius Gen3 Inverter Hacking

[bones]

Hello everyone. This is my first post on the forum. I am an electrical engineer, although my experience is mostly in software, but I can still get by on the hardware side. I converted my first vehicle to electric drive back in 2011 and I am still driving it every day. It is a Subaru Forester, with a Warp 9 DC motor, a Soliton 1 controller and Thundersky 160Ah cells.

EV technology continues to progress and the quality of the components continues to improve while the prices of salvage EV parts continues to drop. I am very excited about using the Prius Inverter in future projects.

I have been thinking about how to use the Prius converter as a battery charger and I wonder if I am thinking about this the right way.

The rectified mains voltage would come in to the inverter converter where the battery would normally connect in a Prius, then the battery of the EV would connect in parallel to the main capacitors on the DC bus inside the inverter converter - right? (see sketch).

To get the most power into the battery from a current limited AC mains source (say 15A, 240V breaker) the power factor becomes a 'factor' (how much so, it not really clear to me).

The good news is that the power switching architecture of the converter looks like it is suitable for power factor corrected current draw. By pulling current from the mains 'in synch' with the waveform of the voltage, you can pull maximum power from the mains (for a given mains current limit). The amplitude of the current waveform draw can be chosen so that the desired average battery current is pushed into the battery.

However, the Atmel micro that is controlling the converter in Jack Bauer's design needs to be aware of the mains voltage phase. Looking at the schematic, I don't see there is this capability. I am not sure how to include it, but this may be a feature that could increase the capability of the charger with limited number of added components on the logic board.

What do you guys think? Is this how it works, or am I out to lunch?

Bones (Toronto, Canada)

[Jack Bauer]

That's exactly the idea and you are correct that the micro currently does not have any mains voltage phase sense. My plan was/ is to see if it will work at all and then upgrade the hardware to correct the pf. I hope to get back to this soon but I've sold out of boards and have an insane project load going on:)

[arber333]

Yes well my idea is more of a powerhouse.
I would connect in opposite. First i would connect 3phase lines directly to transistor bridge where diodes would serve as rectifiers. That is how i would get 600Vdc on input.
Then i would connect main EV battery of 380Vdc downstream of inductor and pushpull block. You are correct there should be current control with output voltage control implemented. BUT If we already know what the input voltage would be - say 580Vdc at maximum strain we could just calculate correct buck function to output say 45A to get 20kW from EVSE. Control could then be much simpler.
What is the working frq of the inductor, anyone knows? I would like it to be some 16kHz so i wouldnt have to listen it whine.

A

[bones]

I am going through the BOM on the github for Jack's board design for the Prius Gen 3 controller. For resistors: R57,65,118,167,173,175 the 'value' column says 2K2, but the RS Pro component it calls out (part number 804-6455) is a 1.5K ohm resistor. Which is it?

[MattsAwesomeStuff]

I am going through the BOM on the github for Jack's board design for the Prius Gen 3 controller.

I'm of no help, but very much interested in the BOM, so, do share when you've got it.

[johnspark]

I have been able to get one of the Prius Gen 2 3 phase motor connectors to fit a Prius Gen 3 inverter connector by shaving a bit off of the sides of the flat connector. This took about 15 mins work.

At the moment, I have not been able how to work out how to convert the second Prius Gen 2 cable to Prius Gen 3 inverter connector.

Interestingly, the silicone gland diameter for the Gen 3 connector is the same diameter as for the Gen 2 connector gland.



Only tools i needed were a vice, file, and small screwdriver to pop out the white plastic inserts, -and of course the original Gen 2 and Gen 3 orange connector housing.

[bones]

Hi Damian,

I am looking at the schematic for the Prius Gen 3 inverter/converter and I have a question about isolation.

Is there a need for isolation between the logic board 12V input and the gate driver transistors? (isolated power supply, opto-couplers and all that stuff)?

There seems to be a single ground in the schematic. Does that mean the 12V system (that is grounded to the car) is grounded with the high voltage pack. Or is there isolation provided by the gate driver board in the Prius inverter?

Also, I really love you idea about using the boost converter as a battery charger, but what about isolation for that guy too? I mean, if your mains is grounded does that mean you high voltage pack is grounded to the mains ground when the charger is connected? That could be dangerous if you work on the batteries while the car is plugged in. Would we need to add an isolation transformer in front of the charger to make that better?

You really need a couple engineers on staff to keep up with your projects. Seriously, can you get some students for free from a nearby college or university. I bet they would love the chance to work on your projects, and they would learn a few things along they way guaranteed.

-bones

[Jack Bauer]

Isolation is handled by the toyota driver board.

[bones]

Damian,

Have been hunting around, looking for a Prius inverter that is the same as you have. I found this website:
http://www.toyodiy.com/parts/xref and they provide cross referencing / compatibility for Toyota parts as installed in the cars.

I found your inverter label on the DIY electric car forum:

When I put your part number in the website above I don't get a match.

Can you provide the VIN number of the car that your Prius inverter was taken from? That can be put into the website to see what other inverter part numbers are 'compatible'.

Now, I put 'compatible' in quotes, because this website is concerned with the outside connection of the inverter to the vehicle. We are mostly concerned with the logic board size & shape and the electrical interface to the gate driver board.

-bones

[Teknomadix]

When I put your part number in the website above I don't get a match.

We have a number of these inverters. All taken from N. American market Prius. They all have the same number.

https://photos.app.goo.gl/p5QvGvCi7bQTgFiA7

[bones]

Are they for sale?

[Jack Bauer]

I know it's been a while since I updated the Gen 3 prius design but I have been paddling away under the surface. Met with my pcb maker last week as there are a few boards due to customers and I have a lot of people contact me wanting to order. They are a small outfit and have struggled with the density of parts on the V1 board resulting in delays and quite a few ruined cards. So my apologies to people who have been waiting on delivery.

Spent some time brainstorming and looking at ways to simplify the design and have something much more workable on the way. The V2 design has the following mods :

- Uses the STM32F103C8T6 so called "blue pill" development board to cut cost and ease assembly. These boards are available for as little as 1.50 Euros from ebay and other Chinese suppliers. This is the 48 pin part so some i/o is lost but can be accessed via CAN if required.

-Removed as many descrete resistors as possible and substituted resistor networks.

-All descrete passives now 1206.

-As the prius power stage is indestructible deleted the hardware overcurrent circuit but the fault outputs are still retained and provide a hard shutdown via the bkin pin.

-Dual channel can transciever.

-Low part count Stereo audio amp used for resolver excitation.

-Arduino nano clone board to run the dcdc and boost converter instead of smd parts version.

To make this more accessibale to people I am considering offering it in kit form either as a complete diy kit or with all the smd parts placed. Feedback on this much appreciated.

Attached a mostly complete schematic just a few more bits to add:)

[celeron55]

Those seem like very reasonable changes. I always tend to go for cheap chinese clone boards as modules in my own designs.

The post messed up delivery of my prius gen3 inverter so I haven't yet seen it nor started soldering a V1 board.

[Dilbert]

Looks interesting, should really reduce part count. Would it be an idea to put jumpers on the accelerator inputs to allow for a separate pot to each controller or a dual pot setup which is mapped to both controllers.

[Bigpie]

Those of us waiting for boards, are we getting V1 or V2 now? I'm easy either way.

Had it been available in kit form, I would have gone for that. With regards to using the clone boards, there's no sense in soldering up the circuits when they can be had for so cheap ready made.

[johu]

Can you make sure that I can reliably detect the hardware variant in software e.g. by pulling a free pin to a known voltage? That way we can keep the unified software

[Jack Bauer]

Will do. I have a spare pin we can use.

[MattsAwesomeStuff]

Damian - Thanks for the updates!

People on DIYEV forums have been asking again and again what they can do for an inverter, and I've been saying "Damian's working on something to hijack Prius Gen 3 converters"... and then have been saying "... but he's sold out right now I think".

I really do think this is the best cheap DIY option for AC motors, maybe the only cheap option. Lots of people are waiting on this to become a thing.

Just wanted to let you know that, when you do these things, people notice and it does matter.

[johnspark]

Those of us waiting for boards, are we getting V1 or V2 now? I'm easy either way.

Had it been available in kit form, I would have gone for that. With regards to using the clone boards, there's no sense in soldering up the circuits when they can be had for so cheap ready made.

I am the same as Bigpie, i am happy either way. Kind regards.

[Jack Bauer]

As long as it suits everyone they will be v2 boards. I have no bare v1 left as the pcb maker ruined them.

[johnspark]

I would like to use the gen 3 inverter with as higher battery voltage as possible. It seems from this forum nominally 308 volts is the maximum that can be safely used, or with lithium batteries with max allowable voltage of 3,6V per cell, 3.6*85 = 306 volts. Probably stick to 83 cells for more safety.

Power Perspective
Next I would still like to use the boost converter, which is rated for 27kW. I only need it to go to 500 Volts, so it only has to cover 300 to 500V not 201.8 to 500 Volts. If I want maximum 50kW power at 500V, means I need 100 Amps at 500V. 300V battery provides 30kW, DC-DC inductor only needs to provide remaining 20kW -which is within the 27kW rating.

From current perspective, according to the "Evaluation of the 2010 Toyota Prius Hybrid Synergy Drive System" by ORNL, the capacitors of the DC DC link were tested to 200Amps at 2khz page 35. This suggests the inductor can take at least 150amps. Locked rotor tests were performed up to 250amps (very short time) page 61. All these investigations tell me the inductor IGBT capacitor system can take 150 amps with a little extra for short time.

i intend using plenty water cooling..

Am I on the right track?

[arber333]

I am sure that if you use 500Vdc battery you can control IGBTs directly then phase amp limit is IGBT capability. You would have to leave out DCDC section though, but you can use one Volt DCDC unit in that role.
You can then use the other IGBT bridge as a fast (buck) charger to charge from 3phase 580V rectified to 500Vdc battery. Inverter will think it is in regen .

[johnspark]

Thanks arber333 for that . I still want to use the other IGBT bridge because my set up is for the Gen 3 inverter to control a Gen 2 Prius transaxle. I have had a shaft made to join the generator and motor together. So plan to use the motor most of the time, then for higher speeds use the generator as a motor to help provide a bit more power at the higher speeds. I will be using this shaft to couple to a 5 speed gear box. So i could do test runs to see what is the highest voltage i want and only build a battery pack for that voltage.
The workshop i am getting to do most of the mechanical build are transitioning to an EV maintenance workshop and giving me EV club rates . Also going to let me use their new dynamotor for free...
Then as you suggested use DC DC converter for charger. Happy with slow charge for first EV. I will have an electric oil pump circuit which i can have a cooler built into as well as a big radiator for the water cooling circuit. So with all this cooling, hope to make this hybrid (part-time) motor work as a full time EV motor.

[arber333]

Ok, fair enough. I expect you will get more RPM from DCDC rig. But with 500Vdc directly you would get much more torque. BUT you must not use more than 540Vdc since 3phase voltage sag at 30A is like 550Vdc rectified (together with conduits and cap ESR).
I am not sure why use another transmission. It means additional drag and weight.
Say you put 4 gears in the PSD to couple MG1 and MG2 directly then PSD device will become a rigid clutch. No need to weld it. But then you would only have rpm up to some 100km/h or maybe 120km/h. Still for light EV would be enough.
However if use gen 3 transmission P410 you have an option to turn MG2 against MG1 and use the ratio to get more speed out of the system. I think it is the better option.

[johnspark]

Higher torque at higher speeds will be much more important, so that sounds better to just have batteries directly onto the HV bus (<= 500Vdc). I am only using the Gen 2 transaxle because it was the first one i got and would like to learn what I can from it first. I was also keen to reuse the Prius transaxles because they were readily available and reasonably priced, and i thought it was useful to try and reuse something that would otherwise end up at the tip and waste those permanent magnets. I am not using any gears to couple MG1 and MG2 together. I have had a shaft made that mates the MG1 and MG2 splines together, with a smooth 25mm dia. round surface which I will use to connect to the manual gear box. I am only interested in 120km/h because we can only go up to 110km/h on the roads where i come from.
Interesting what you state about the gen 3 transmission P410, but will try to get some return from what i have first.