Archive for February, 2011
Volvo recently released the specs on their V60 plug-in hybrid diesel calling it “the world’s first diesel plug-in hybrid”. Wrong sir, wrong!
The Audi duo was the world’s first diesel plug-in hybrid, not the Volvo V60 There were earlier concept cars but the 1997 Audi duo was a production car and sold to the public.
It combined a 1.9L TDI engine with a 28 hp electric motor. Only about 60 were built and they didn’t sell well due to the heavy weight and high price. Here is an earlier post about the audi duo: http://www.evwaudi.com/2010/11/audi-first-to-have-plug-in-hybrid/
Even still, you don’t get merit points for best car on being first. In fact, the Audi duo was a bad hybrid compared to today’s cars. The Volvo V60 has a 215 horsepower and 324 pound-feet of torque, while a 70-horsepower electric motor. The electric motor only powers the rear wheels. It can also drive about 30 miles on electric power alone. So would I rather have the Volvo V60 or the Audi duo? Yes the Audi duo gets points for being first but so does the first generation Prius and I wouldn’t want to own either. For one thing, where would you get replacement parts?
Part 2 of the interview below: Rupert Stadler talks about technology features on new cars.
One interesting things in the specs listing below: the electric motor is 3 phase.
Combustion engine output: 329 hp
Electric motor/generator: 3-phase AC motor/generator
Electric motor/generator output: 51 hp (38 kW) generator output (electrical output)
45 hp (34 kW) motor output (mechanical output)
Maximum output during electric boost: 375 hp
Maximum torque during electric boost: 405 lb/f
High-voltage battery voltage: 288 V (2x144V)
High-voltage battery capacity: 6 Ah corresponding to 1.87 kW/h
What is the 3 phase motor used on the VW Touareg hybrid and Porsche Cayenne hybrid?
Simply put, it’s an alternating current (AC) induction motor with 3 currents instead of 2 like normal household current. It’s used because it can can generate a lot more torque than 2 phase. The power electronics module converts the 288 Volts of the DC battery to 3 phase AC voltage that is used in the motor. 3 phase motors are also used in the Prius and probably other hybrid cars due to the power loads.
You won’t find 3 phase in most homes because most appliances couldn’t use it. Some commercial and most industrial sites use 3 phase. Some other benefits of 3 phase electric motors:
- The phase currents tend to cancel each other out, resulting in a linear balanced load. This lets the neutral conductor be smaller or take out entirely. All the phase conductors carry the same current and therefore can be the same size.
- Power transfer into a linear balanced load is constant which helps to reduce vibration in the motor.
- 3 phase can produce a magnetic field that rotates in a specified direction, which simplifies the design of electric motors
In the last 3 sections, http://www.evwaudi.com/2011/02/how-to-safely-disconnect-vw-hybrid-battery-high-voltage-line/ , the safety connector at the engine was shown. This article will show the High Voltage System Maintenance Connector at the battery pack. Always disconnect this when working on the high voltage electrical system.
You disconnect it by removing the cover flap and then pulling it up in a perpendicular position.
This is under the orange flap in the picture below.
How to remove the high voltage line on the VW Touareg hybrid or Porsche Cayenne hybrid. May also apply to Audi A6 hybrid, VW Jetta hybrid
In the last article, part 2 of a series: http://www.evwaudi.com/2011/02/how-to-safely-work-vw-touareg-hybrid-disconnect-electrical-system/ on how to disconnect the battery pack on the VW Touareg hybrid and Porsche Cayenne hybrid, the safety line and how it works was discussed. This article is the final part on this topic and shows how the mechanical lock on the high voltage line works.
Again, the official literature says that only a trained VW High Voltage technician can remove the maintenance connector. First, remove the safety connector. This prevents the high voltage lock from moving. It also prevents the high voltage system from being supplied with current. If you read part 1 and 2, you will see how this interrupts the safety line. The battery management unit then decouples the high voltage battery through the relays. As long as all systems work as intended, there will be no voltage at the high voltage line and you won’t get shocked when removing the high voltage line.
The safety connector also physically blocks the locking bar from swiveling out of the way. Then swivel back the locking bar. The cable can then be removed. This is shown in the illustration below.
In the last article: http://www.evwaudi.com/2011/02/how-to-safely-work-vw-touareg-hybrid-disconnect-battery-pack/ the main safety switch was described.
This article will describe how the safety line works to disconnect the electrical system on the VW Touareg hybrid and Porsche Cayenne S hybrid.
Safety line closed:
The VW Touareg hybrid’s high voltage elements are linked by a separate low voltage loop line. Each connection with the safety line is designed to act like a contact breaker point. When all components are ready to operate, the contact breaker points are closed. When the safety line sees voltage, current is able to flow because the line is not interrupted. The presence of current indicates that all of the safety line’s components are ready to operate. The function of the safety line is comparable with cold monitoring in the case of bulbs.
Safety line open:
If any point is open the safety line is interrupted. This could be if any component is not ready to operate or because the safety connector has been removed. In this case, there will be no current. This indicates that the high voltage system is not ready to operate. The check to determine whether the safety line is closed or interrupted is carried out by the voltage converter. If the control unit determines that the line is interrupted, it actuates the protective relays and interrupts the high voltage battery’s connection to the high voltage system.
Below is an illustration from VW’s literature showing the safety line.
One concern of working on hybrid cars for DIY’ers is how to work around the hybrid electrical system. It’s not only amps or only volts that is dangerous, it’s enough of the combination of enough either volts or amps that can injure you. Comparing electricity to water, you can think of amps as the volume of water and volts as the speed that it moves. You’re not going to get swept away in a river unless there’s enough water and it’s flowing fast enough.
The electric safety line in the VW Touareg hybrid and Porsche Cayenne hybrid
The battery pack in these cars is 288 volts and more than enough amps to cause serious injury. If it has enough energy to move a car it has enough energy to jolt you. Therefore, take safety precautions when working on them. There are a few safety measures:
• The electric safety line with safety connector
• The ignition lock
• The battery regulation control unit relay
• The airbag control module
• The maintenance connector
In this first post in a series, let’s look at the safety line and connector. The safety line guarantees that the entire high voltage system’s voltage is turned off as soon as a high voltage component is disconnected from the system. Together with a locking bar, the safety connector forms a mechanical lock, which prevents the high voltage lines from being disconnected while voltage is present. The safety line is an electrical circuit that is closed by safety connectors. If this circuit is opened by removing the safety connectors, the high voltage system shuts off.
The safety connectors have to be removed before high voltage lines can be disconnected from the high voltage components. This guarantees that the system is not conducting voltage when the lines are disconnected. It is shown below.
One common complaint of hybrids is that they cost more and that it will take too long to recoup that price premium in fuel savings. This is faulty logic because much of the price premium is recouped during resale. The cost to own something is not the purchase price, it’s the depreciation.
As an example, if the price premium to buy a VW Jetta hybrid is $2500, when it comes time for resale the desirability of the car is undiminished and could sell for $1500 over the price of a regular Jetta. Therefore, the additional cost to own the hybrid is only $1000 plus opportunity cost/interest of the cash. Federal tax credits have ended but when they were giving out money to buy fuel efficient cars or giving sales tax exemptions, it was a no brainier to buy a more fuel efficient car.