leitmotif
Member
The Great Electric Vehicle Project has started.
To review
Vehicle is a 56 Chev 1/2 ton pickup. I intend to as much as possible ensure truck is easily returned to stock condition ie put an engine back in etc etc.
Drive motor is a 3600 RPM 50 HP Leeson 208 / 230 / 460 motor.
Motor is in a prototype cradle to enable final measurements prior to making foundation bracket.
VFD is not selected yet. Thinking Hitachi SJ 300 or Yaskowa or ABB. Open to suggestions of course. Reliability and safety are top considerations, cost is further down the list.
Since we have a few hills here in Seattle downhill speed control is to say least right handy.
I know I can feed DC into the "normal" AC line connections but I lose braking and I gotta ovesize the VFD.
SO
Battery will be tied direct to DC bus. DC bus voltage is at this time nominal 325 VDC (1.4 x 208 VAC). Battery fused of course and disconnect means of course.
I am told by several that this will work fine as a load bank (snubber) when motor is in generating "mode" ie overhauled on downhill.
HOWEVER
they are unsure about battery voltage getting too high and feel that I cannot use added braking resistors controlled by the VFD. They think an additional control must be emplaced to sense battery voltage and parallel resistance as needed to keep DC bus voltage (and the battery) below max set by VFD mfr to protect DC bus.
Worst case scenario for this problem - fully charged battery and braking is needed to go downhill. Battery is "full" and voltage will rise of course.
I have not selected battery nor battery chemistry yet. Am thinking lead acid since I know and understand that best (former submarine electrician) and am willing to pay the weight penalty. It is also more forgiving of my future mistakes which I am sure I will make. After I get bugs and oversights dealt with I may go with a lithium battery.
SECOND QUESTION
I will definitely use a vector VFD. I believe V/Hz will have too hard a time starting on hills. What I am uncertain on is whether I need to sense both motor shaft RPM and shaft position for this application. I do not think I need to sense shaft position since I do not care about accurate positioning of vehicle.
Thoughts and opinions on this please. Dick DV you can surely chime in here.
Dan Bentler
To review
Vehicle is a 56 Chev 1/2 ton pickup. I intend to as much as possible ensure truck is easily returned to stock condition ie put an engine back in etc etc.
Drive motor is a 3600 RPM 50 HP Leeson 208 / 230 / 460 motor.
Motor is in a prototype cradle to enable final measurements prior to making foundation bracket.
VFD is not selected yet. Thinking Hitachi SJ 300 or Yaskowa or ABB. Open to suggestions of course. Reliability and safety are top considerations, cost is further down the list.
Since we have a few hills here in Seattle downhill speed control is to say least right handy.
I know I can feed DC into the "normal" AC line connections but I lose braking and I gotta ovesize the VFD.
SO
Battery will be tied direct to DC bus. DC bus voltage is at this time nominal 325 VDC (1.4 x 208 VAC). Battery fused of course and disconnect means of course.
I am told by several that this will work fine as a load bank (snubber) when motor is in generating "mode" ie overhauled on downhill.
HOWEVER
they are unsure about battery voltage getting too high and feel that I cannot use added braking resistors controlled by the VFD. They think an additional control must be emplaced to sense battery voltage and parallel resistance as needed to keep DC bus voltage (and the battery) below max set by VFD mfr to protect DC bus.
Worst case scenario for this problem - fully charged battery and braking is needed to go downhill. Battery is "full" and voltage will rise of course.
I have not selected battery nor battery chemistry yet. Am thinking lead acid since I know and understand that best (former submarine electrician) and am willing to pay the weight penalty. It is also more forgiving of my future mistakes which I am sure I will make. After I get bugs and oversights dealt with I may go with a lithium battery.
SECOND QUESTION
I will definitely use a vector VFD. I believe V/Hz will have too hard a time starting on hills. What I am uncertain on is whether I need to sense both motor shaft RPM and shaft position for this application. I do not think I need to sense shaft position since I do not care about accurate positioning of vehicle.
Thoughts and opinions on this please. Dick DV you can surely chime in here.
Dan Bentler
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