Hello everyone, I would be very grateful if I could have some advice regarding my project.

My task is to connect the HV battery of a plug in series hybrid vehicle to the motor using the appropriate converter. I will need to boost the voltage from approximately 280V to 700V. This connection needs to be bidirectional because the motor is operating as a generator during regenerative braking and needs to charge the battery back. However the generator's output is Ac so I will need an Ac/dc inverter as well.

the last part is to connect another generator driven by the Internal Combustion Engine to charge the battery but also with the ability to drive the motor directly.. This will need another ac/dc inverter.

For the first part I was thinking of an isolated bidirectional dc-dc converter followed by a buck boost. I would like to ask if you know any literature that give a similar solution to this problem, preferably sources that provide all the relevant equations.
Also I would be pleased if I could find some relevant simulations of the above converters in Simulink.

I can provide the vehicle's schematic which shows all the relevant connections and also the simulink files of the motor and the generators upon request, if you need it to offer any advice.

Thanks a lot in advance!

 

This will be one hell of job buddy. you are talking about high DC voltages at high current levels, not a simple task for beginners.
I know these because I have repaired hybrid vehicle power inverter and chargers.
These contain components that are custom made, but if you got the budget you can do this.
Plus boosting 280 to 700V is not easy, we a talking about high current levels. You'll need a DC to DC converter plus a switching circuit to charge the battery during braking.
This has to be well designed, and these are made in factory's for that vehicle, and a lot of testing is done too, not the off the shelf type circuits.
Think about it, we can try.

Rifaa

 

A couple of questions to clear a few things up.

What is your level of expertise?

You are using an AC motor for the drive? If so, why? This would seem to complicated things a bit.

Multiple inverters seem to offer the opertunity to share some components.

 

Boost from 280 to 700 volt? That seems rather an extreme step. Are you sure about these?
Most buck/boost I have encountered use a duty cycle to step up or down, which is calculated through D = Vout / (Vout - Vin). To have any control (decent control) you want your duty cycle to be in between 0 and 1 yours would end up at 1.6, which is not good and actuall defeats the object of a duty cycle.

For articles about buck boost search for these using google, you'll be surprised; or the IEEE database if you have a subscription (www.ieee.org).

 

I don't have a problem with the voltages, we are talking cars working off batteries, and voltage means less current for the same wattage.

 

Come to think of it, hybrid has a battery bank that is equal 240V DC and the motor is a 3 phase, donno what voltage motor uses cause never tried to dismantle a motor of a hybrid before, but the inverter/motor driver uses 240V DC. This I have seen.
Where this 700VDC comes in to play

Rifaa

 

I am a 4th Year student, I am not much of an expert and I have a very tight time constraint of 2 weeks which makes it even more difficult. I will have to come up with a few ideas - solutions to the problem and try to simulate them in simulink by connecting the already designed motor and generator.

THe motor is a Permanent Magnet Synchronous Motor which is a Brushless DC motor that uses a synchronous mode of operation. I am not required to know about it in detail, it just needs to be supplied by constant voltage of 700V as previously mentioned. This is a bit higher than usual but not surprising- common value is around 600V.

Someone mentioned that it is too much of a step -up in voltage. How about making this in 2 steps if this poses a problem?

Do you have any simulations in simulink of isolated bidirectional converters, buck-boost or ac/dc inverters?

Thanks

 

I don't have simulation but I do have a 3 phase DC motor driver Assy.

Rifaa

 

Try breaking it down into parts and how they connect. Sort of a cross between a schematic and a flow chart.

 

"2 weeks to do it" ???

2 weeks to do a task that's normally delegated to an engineering team of a few people over a year or so?

How many other people on the team? Why have you only been given 2 weeks???

 

DC-DC converters would be your best bet, I think.
If you have the electronic package within simulink you should be able to build your own bidirectional dc-dc converter using PWM to control the output voltage.
Look for "di Napoli" or "Rosario and Luk" in the IEEE database and there you'll find most of your starting answers.
There is also a package called QSS for simulink, which allows you use blocks for EV simulation, maybe that is an idea?