The Conversion ProcessQuick Links to view the EV components seen on this page This EV conversion is provided by Bob Simpson of Performance EV in Portland Oregon. www.evdrive.com Check his web site for more information. My goal is to make all of the parts need to do a conversion here in America by American workers.
1. AC 3-phase motor. We want Americans to
make light weight aluminum motors that will match or exceed the OEM's ICE horsepower
and torque in American factories.
Size is 9.6 inches square by 17 inches long, not counting the shaft, which will be cut down to 1 inch in length. weight is 200 lbs.
Here is a direct comparison before and after. Funny that the smaller electric motor, with 1 moving part, has twice the performance of the big, complicated, and wear prone engine. Since motor compartment space is needed for the battery pack, I need to shorten the output shaft length to mate with the transmission more compactly. A custom adaptor plate will be mounted to this shaft stub that the flywheel/clutch assembly will bolt to. This shaft adaptor plate will bond with a precise interference fit on the short 1 inch stub.
The pilot bearing (blue seal visible), will be mounted in the new shaft adaptor to make it fit with the transmission input shaft just like this original crankshaft mounted plate did:
Mounting the motor to the transmission involves two primary tasks: 1. Adaptor plate design/construction - motor face to transmission bell housing face 2. Shaft adaptor design/construction/installation - mounts flywheel to motor shaft Here I have placed them shaft-to-shaft, level, and in their proper orientation to look for any conflicts on the bolt placement around the bell housing relative to the electric motor. The primary thing to look for is places where a bolt from each side of the adaptor plate share the same location or overlap slightly, interfering with each other. Bob is happy to report that there are no bolt location conflicts in the planned orientation. If there were a conflict, the motor could be rotated slightly one direction or the other to allow clearance, as long as the shafts remain in concentric orientation.
Bob will be shortening the Siemens motor shaft by 3.25 inches that will leave exactly 1 inch between the two faces, the thickness of the aluminum adaptor plate I will be using. This will make the package much more compact and allow the use of the space for more cells. Task #1 is relatively simple but needs precision with the alignment between the two shafts which is critical. I have a method planned for this alignment task that I will show next update. Task #2 is not so simple and must have a specialist involved to properly size the shaft adaptor to create the interference fit/mount that will handle a lifetime of torque delivery. This design uses undersized adaptor dimensions that are expanded with temperature shift to momentarily allow the adaptor to slide onto the shortened shaft. The temperature quickly equalizes and bonds them permanently (short of grinding it off and starting again). This is why the need for the specialist... The other part of this design detail is that I will be imbedding a pilot bearing in the adaptor, just as the original motor had see photo above to allow the use of the clutch. I have located a potential specialist in California and will be sending CAD files to get this started with him. Return to top of page Return to Home Motor mounting Tasks: 1. Done May 19, 2008. The updated modeling has proven that the motor rotation will work well. The electrical box is stepped at the corner giving the needed clearance to the steering rack power steering assembly. I may need to mill off a small piece of the casting which is the white box clears the steering assembly and gives more room for battery pack clearance above the motor. This
2. Remove transmission and digitize (accurately measure) the transmission bell housing for CAD input
3. Design/CNC mill the adaptor plate that will mount the
motor to the transmission precisely 4. Construct motor mount bracket to the new motor position A side by side look at the gas vs. electric drive system:
This is the view from the back
Here is the view from the front
Evisol 200 DC to AC 3 Phase High Voltage Power InverterHere is the inverter with it's top cover off (Also see Inverter / Motor controllers in Pictures & Pricing)
This is a 200kW motor controller designed for the Siemens 700 Volt AC induction motor. It is calibrated for a specific motor type. It fits perfectly. The front face of this box fits up against the back wall that will be this BMW's battery pack. All the water cooling plumbing and wires also have clear paths.
On this Evisol 200 the three yellow cables are the 3 phase drive wires into the motor. The black cable passes the motor's rotor position data back to the Evisol 200 inverter to maintain synchronous control.
Battery Pack Bob used 123 batteries with the same LiFeP04 chemical make up as LifeBatt batteries. They did not come with the VMS or global tracking that LifeBatt offers. We want American made Lithium batteries in American factores at affordable prices.
This 3.3kW charger can charge to a maximum of 720 Volts, just enough to top off the 720 volt battery pack. (Five 144 volt batteries) Not needed on all applications.
Each of these LifeBatt batteries can be ordered with 12 to 144 volts making them easy to fit into the gas tank area of most vehicles. They come with the Battery Voltage Management System (VMS) software to program the charging profile. They can be charged with a 220 VAC outlet for charge time around 3 hours. If plugged into a 120 VAC outlet, the time to charge doubles. They can also be charged with our optional on board battery charger / generator. The charger's output is isolated from the AC mains for safety. Bob used the Brusa charger to charge the battery packs. I like it because and it can be water cooled using the existing radiator platform to make the air cooled unit more compact and efficient. . DC to DC converter The alternator is replaced by the DC/DC converter that charges the vehicles existing 12 volt battery that powers the vehicle's remaining 12 volt electronic battery powered components.
This unit converts the 700 VDC battery pack output down to the 12 Volt level to maintain the charge in the existing automotive power system just as the alternator did with the original gas engine. Being electronic, it will allow using lights and accessories independently from driving, because it is always connected to the power source (as are all other functions, i.e. heating, cooling etc.) Return to top of page Return to Home Distribution Contactor Box
These special contactors and the pre-charge circuitry
are in safely inside the distribution contactor box with secure cover to prevent
electrical shock. It fits into the motor compartment, along with the contactor/fuse for the ancillary connections; charger, DC/DC converter, fluid heater, and air
conditioner compressor. The battery pack wires are run in the
undercarriage of the vehicle and are protected with an aluminum conduit. Interior heating and defrost
This 4000 Watt unit heats fluid that is pumped through the interior heater core. From the inside, the heating and defrosting system will operate in the original way except for being quicker to deliver heat since there is no delay in fully heated water. The power for this comes from the main battery pack and has a relatively small effect on driving range because of its low duty cycle (percent of time the unit is actually on). The quickness of this heat source makes the factory electrically heated seats almost unnecessary. Since there is not a lot of excessive heat generated from the motor / Inverter drive system, this unit instantly heats the water for for use in the interior. This way, you only consume energy when needed for the comfort of the human occupants. The vehicle's existing radiator and fan are still used to cool the heated water so that it can be circulated to other water cooled components that you might use in your EV. Return to top of page Return to Home Vacuum pump
This is a quiet little unit that runs only when there is some use of the hydraulic/friction brakes, which will be less often now because of the regenerative braking ability. Regenerative braking, not only will that make the brake pads last longer, there is no wear mechanism involved with recovering the power from braking. Return to top of page Return to Home Air Conditioning compressor
A variable speed AC motor is built into this compressor unit. This makes it quite compact. In fact, this compressor (with built in motor) is slightly smaller than the original BMW compressor that was driven off the gas engine. It will reside in the cavity next to the primary drive motor, directly below the plumbing that passes through the fire wall and into the interior. It is designed for the standard R134 air conditioning fluid.
The original condenser, evaporator and drier units are still used in their original locations making this a straight forward conversion. Since this will be connected to the main battery pack, it can operate at any time, no longer tied to a running gas engine. Yet another advantage over the original design, it's speed is adjustable to allow running only the level of cooling desired without cycling on and off to regulate. The compressor will mount to this undercarriage structure, along with the vacuum pump (behind) and interior fluid heater on right side:
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Power Steering pumpSince most vehicle's have a power steering pump driven off the engine, we use an electric power steering pump. All other components from the original power steering system will be used.
This
Brusa 3.3kW charger can charge to a maximum of 720 Volts, just enough to top off
the BMW's battery pack. This is compact enough to fit into the BMW's optional battery compartment
that was empty from the factory on this model, since they put the 12V battery
in the trunk for better weight distribution. The charger comes with software to program the
charging profile. It can be plugged into 220 VAC
outlet if available for charge time around 3 hours. If plugged into a 120 VAC outlet, the time to
charge doubles. The charger's output is isolated from the AC mains for safety.
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