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Print 55 comment(s) - last by EricMartello.. on May 15 at 1:55 AM

First time eDrive and xDrive tech has been combined in one vehicle

BMW has unveiled the Concept X5 eDrive, which will be showcased at the New York International Auto Show. Although the vehicle is labeled as a concept, it’s a dead ringer for the production plug-in hybrid version of BMW’s popular crossover that it plans to bring to market sometime within the next year or two.
 
The hybrid drive system gets its primary motivation from a 245hp turbocharged 4-cylinder engine. That gas engine is combined with a 95hp/184 lb-ft electric motor developed by the BMW Group. Power for the electric motor comes from a lithium-ion battery pack (which is mounted under the cargo area) that can charge from any wall outlet.
 
The Concept X5 eDrive can drive on electricity alone for up to 20 miles at speeds up to 75 mph. BMW says that the car will have an average fuel consumption of over 74.3 mpg in the EU testing cycle (which means we’ll likely see less than half of that quoted figure under EPA guidelines). BMW says that the X5 concept can reach 62mph in under 7-seconds.

 
The Concept X5 eDrive is the first from BMW that uses its xDrive all-wheel-drive system paired with eDrive hybrid technology.
 
The concept also has a ConnectedDrive system that helps plan routes and lists the location of charging stations on the GPS map. This allows the driver to find a charging station when they are around town in electric mode.

Source: BMW



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RE: Tesla!
By snhoj on 4/15/2014 9:47:22 PM , Rating: 2
quote:
You say no, and then basically say what I just said followed by something you paraphrased from wikipedia in an attempt to seem smart but likely don't understand.


I'm not paraphrasing anybody!! Because your statement implieded that torque drops off (sharply) from zero RPM I stand by my disagreement with that.

quote:
Voltage determines the speed of the engine; the current drawn will rise if a load is placed on the motor (which causes a drop in voltage). Current itself is limited by system wiring and the motor's windings, and exceeding this current would cause the motor and/or wiring to overheat.
Will be funny to see what happens if a Tesla motor stalls while stuck at "full throttle". It will basically weld itself into a clump of molten metal in seconds.


You might know the electrical theory but you don’t know how EV’s work. The motor controller will limit the current available to the motor. At low motor RPM it will chop the voltage to ensure that the current doesn’t exceed its preset limit. This is what I call the current limited phase. As the current available is the preset limit it is constant as is available torque. It’s the motor controller that limits the current not the load. Of course that is semantics as the load will increase to match the current i.e. the car will accelerate there by loading up the motor. As the motor crosses peak power (maximum voltage, maximum current) the back EMF generated by the motor is sufficient to prevent the current from exceeding the preset limit of the controller.

If the Tesla was floored while resting against an immovable object the motor controller would limit the current flow and protect the motor just as it would even if the car wasn’t stalled.


RE: Tesla!
By EricMartello on 4/16/2014 4:34:10 PM , Rating: 2
quote:
I'm not paraphrasing anybody!! Because your statement implieded that torque drops off (sharply) from zero RPM I stand by my disagreement with that.


It does, and it must, as power is a derived value that's calculated from torque x RPM.

The point is that electric motors' having full torque from 0 RPM is not an advantage over the gas engine. Sure, it makes the car "feel" fast but the performance figures tell the full story, and they're not exactly shattering any records.

quote:
You might know the electrical theory but you don’t know how EV’s work. The motor controller will limit the current available to the motor. At low motor RPM it will chop the voltage to ensure that the current doesn’t exceed its preset limit. This is what I call the current limited phase. As the current available is the preset limit it is constant as is available torque. It’s the motor controller that limits the current not the load. Of course that is semantics as the load will increase to match the current i.e. the car will accelerate there by loading up the motor. As the motor crosses peak power (maximum voltage, maximum current) the back EMF generated by the motor is sufficient to prevent the current from exceeding the preset limit of the controller.


Current itself is not what drives the motor, it is VOLTAGE that makes things move. Voltage must be high enough to overcome the resistance of the system, and when a load is placed on the motor, resistance increases and voltage drops. To maintain a speed at a given voltage, more current is drawn by the motor.

The tesla uses an inverter to drive the motor. The inverter not only increases the battery voltage, but it generates 3 sine waves to provide 3-phase power to the motor. It controls the speed of the motor by varying the voltage and maintaining the flow of current required to sustain a given voltage level.

I do not know the specific operation current of tesla's drive unit, but I would estimate that it can sustain somewhere in the ballpark of 1,000 amps across its operating voltage range.


RE: Tesla!
By snhoj on 4/16/2014 9:09:14 PM , Rating: 2
quote:
The point is that electric motors' having full torque from 0 RPM is not an advantage over the gas engine. Sure, it makes the car "feel" fast but the performance figures tell the full story, and they're not exactly shattering any records.

The advantage is not having to have a clutch or some other device to engage the drive. It’s a mechanical simplification. In the case of Tesla the range of the motor is so broad that it also doesn’t need a gearbox and can make do with a single reduction ratio. A further mechanical simplification. This is of course a design compromise as motor redline limits top speed. A second ratio would allow a much higher top speed. I personally think 125 MPH is more than enough for a road car.
quote:
Current itself is not what drives the motor, it is VOLTAGE that makes things move. Voltage must be high enough to overcome the resistance of the system, and when a load is placed on the motor, resistance increases and voltage drops. To maintain a speed at a given voltage, more current is drawn by the motor.

In an EV we don't want to control the speed of the motor but the torque it puts out. If the accelerator position controlled speed the vehicle would be very difficult to drive. Hence the motor controller manipulates the current by manipulating the voltage but the voltage doesn't bear any direct relationship to the accelerator position. None of this is in disagreement with what you have said I’m just trying to add a different perspective. As for load when you encounter a hill the driver must adjust the accelerator pedal to maintain speed (as you currently do in your ICE powered car) increasing the current to maintain the voltage.


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