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This is probably a really silly question, but....
Is it possible to find a 120V AC motor that can be speed controlled (and maybe even reversed??) for at least a proof of concept on a boat?
For those of us that prefer electric motors to gas or diesel engines, but are challenged by the investment of a huge battery bank, wouldn't it be cool if we could run an AC motor off an inverter from whatever battery bank we have handy, and use a generator to supplement - or just run off the generator entirely at first?
We've discussed the efficiency gain of running off a higher voltage / lower current. I'm guessing that there just isn't a suitable way to control and/or reverse an AC motor??
John
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Setting aside efficiency differences it still takes the same amount of power to move the boat at a given speed.? AC, DC, gasoline, diesel.? Doesn't matter.? The boat wants what the boat wants.?? Higher voltage will be lower amps.?? Lower voltage will be higher amps.? The watts remain the same.?? The sizing of the wires may change but the power needs remain the same.?
An AC motor can indeed be used with a controller that allows for forward and reverse and all the rest.? Your battery bank challenge will remain.?? It may even get larger from more losses through added inverter stages.??
The generator can also work.? For a 6 ton boat you'll need something in the neighborhood of 2000 watts to go 4 kts??? Doesn't matter where you get it or what conversions in may go through making it's way to the propeller.?? If you're going to loose half of it on the way you need to start with 3200.?? An AC motor will work but it won't pick up the check at lunch.?
Dan Pfeiffer
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On 2021-05-25 9:19 pm, john via groups.io wrote:
?
?
This is probably a really silly question, but....
?
Is it possible to find a 120V AC motor that can be speed controlled (and maybe even reversed??) for at least a proof of concept on a boat?
?
For those of us that prefer electric motors to gas or diesel engines, but are challenged by the investment of a huge battery bank, wouldn't it be cool if we could run an AC motor off an inverter from whatever battery bank we have handy, and use a generator to supplement - or just run off the generator entirely at first?
?
We've discussed the efficiency gain of running off a higher voltage / lower current.
I'm guessing that there just isn't a suitable way to control and/or reverse an AC motor??
?
John
|
Interestingly many motors used in boats are PMAC - permanent magnet AC 3-phase motors. These are controlled by a controller (such as Sevcon Gen4) that converts 12VDC to the AC to operate the motor.?
that said, your idea to use an AC motor powered by your existing inverter and battery bank is doing essentially the same thing. You are still using your DC battery to power the motor.?
bottom line - if you want to propel your boat using an electric motor the power has to come from somewhere. Either a generator (serial hybrid) or a battery - which in turn can be charged by solar, wind, shore power or a generator.?
why reinvent the wheel when dc-powered systems are available and proven? Check out .?
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Hi. I am in the process of building the suggested system. ?24v of leisure batteries 70Ah,? 24v to 230v a.c. inverter,? 230v single to 230v 3 phase variable frequency drive? and standard 2.2kw 3 phase motor.? It is going into a Halcyon 23 sailing boat. 84lb thrust, 24v (Bison?) outboard, approx. 1kw as second auxiliary. Found it a bit weak against a headwind on a previous boat, 19ft. Moored on a swinging mooring in a sparsely populated bay in West Cork, Ireland so very little motoring intended (minutes) so I can absorb the losses of all the electrical conversions. I have a backup so I can accept the increased risk of failure of a component.?Cheap chinese components all. Nothing marine rated. I wouldn't recommend this to anyone who was intending travelling too far or at all for a primary propulsion system.? I have milled the motor mount to take a more proven bldc motor if I want to down the line. I am running a 3 to 1 timing belt reduction to the 2 blade prop that was on the boat. I think it's 12d x 10p inches. Original 3/4" bronze shaft to homemade bearing housing. 5206 double angular contact bearing for thrust and 6206 to take radial belt load. Spaced apart for radial stiffness. Probably should be using stainless bearings. Next year maybe. Runs fine on the bench. Won't be in water for another month. I'll document and post it if it is still a success by September.? Recharge via 270w solar. Backup power is by Briggs and Stratton 3.5hp former lawnmower and 24v lorry alternator. Worries: Motor and bearing assembly is mounted hard on to unistrut rails on stringers. No flexible mounts. Packing gland is hard mounted on stern tube. Essentially acts as a mid shaft bearing. Alignment has to be perfect! I think I may have to align the motor again when boat is floating. Don't try this at home, kids. Yet.
Anthony
This is probably a really silly question, but....
Is it possible to find a 120V AC motor that can be speed controlled (and maybe even reversed??) for at least a proof of concept on a boat?
For those of us that prefer electric motors to gas or diesel engines, but are challenged by the investment of a huge battery bank, wouldn't it be cool if we could run an AC motor off an inverter from whatever battery bank we have handy, and use a generator to supplement - or just run off the generator entirely at first?
We've discussed the efficiency gain of running off a higher voltage / lower current. I'm guessing that there just isn't a suitable way to control and/or reverse an AC motor??
John
|
That looks great.? I like the way you used the I-beam section in the assembly along with the angles to give you pitch and yaw adjustment.??? Well done.?? I was going to use a C-channel for my mounting plate but it was not wide enough to accommodate the large belt pulley I needed for my 3:1 ratio.? The big pulley is 60 tooth and relatively heavy (16lbs/7kg) and is a bit of a flywheel.?
I'd like to see more of your bearing housing fabrication.?? I used a 5207 double angular contact bearing and a UCF205-16 flange mount as a pilot bearing on the output shaft of my reduction gear.?? I used a rubber sealed 5207 and made a housing from aluminum.? Not as robust as steel but ZF marine transmissions are aluminum and have to hold similar bearings to take similar loads so I am giving it a try.?
I have a soft mount by having my mounting flanges sit on rubber blocks that sandwich the fiberglass beds of the boat.? The equivalent place would be under your unistrut rails.?
I am at about the same state in my assembly.? Maybe a couple weeks from going in the water.?? I am about to machine the output shaft of my reduction gear unit.?
I am sure you are correct about re-aligning in the water.?
Dan Pfeiffer
?
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On 2021-05-26 12:13 pm, julie Lynch wrote:
Hi. I am in the process of building the suggested system.
?24v of leisure batteries 70Ah,?
24v to 230v a.c. inverter,?
230v single to 230v 3 phase variable frequency drive?
and standard 2.2kw 3 phase motor.?
It is going into a Halcyon 23 sailing boat. 84lb thrust, 24v (Bison?) outboard, approx. 1kw as second auxiliary. Found it a bit weak against a headwind on a previous boat, 19ft.
Moored on a swinging mooring in a sparsely populated bay in West Cork, Ireland so very little motoring intended (minutes) so I can absorb the losses of all the electrical conversions. I have a backup so I can accept the increased risk of failure of a component.?Cheap chinese components all. Nothing marine rated.
I wouldn't recommend this to anyone who was intending travelling too far or at all for a primary propulsion system.?
I have milled the motor mount to take a more proven bldc motor if I want to down the line.
I am running a 3 to 1 timing belt reduction to the 2 blade prop that was on the boat. I think it's 12d x 10p inches.
Original 3/4" bronze shaft to homemade bearing housing. 5206 double angular contact bearing for thrust and 6206 to take radial belt load. Spaced apart for radial stiffness. Probably should be using stainless bearings. Next year maybe.
Runs fine on the bench. Won't be in water for another month. I'll document and post it if it is still a success by September.?
Recharge via 270w solar.
Backup power is by Briggs and Stratton 3.5hp former lawnmower and 24v lorry alternator.
Worries:
Motor and bearing assembly is mounted hard on to unistrut rails on stringers. No flexible mounts.
Packing gland is hard mounted on stern tube. Essentially acts as a mid shaft bearing. Alignment has to be perfect! I think I may have to align the motor again when boat is floating.
Don't try this at home, kids.
Yet.
?
Anthony
?
?
?
This is probably a really silly question, but....
?
Is it possible to find a 120V AC motor that can be speed controlled (and maybe even reversed??) for at least a proof of concept on a boat?
?
For those of us that prefer electric motors to gas or diesel engines, but are challenged by the investment of a huge battery bank, wouldn't it be cool if we could run an AC motor off an inverter from whatever battery bank we have handy, and use a generator to supplement - or just run off the generator entirely at first?
?
We've discussed the efficiency gain of running off a higher voltage / lower current.
I'm guessing that there just isn't a suitable way to control and/or reverse an AC motor??
?
John
|
Hi Dan. That's nice work. Your motor being mounted to one side gives excellent access for checking or aligning the arrangement. Your belt is captive though. Someone suggested leaving the spare belt around the end of the shaft ready to in a hurry. I should be able to roll on my 20mm wide HTD8mm in a few seconds if the need arises.? Bearing block:
I don't have access to CNC machine tools.? I just have a manual lathe and mill. I had a bar end of 2.5" 303 and I faced and bored it to the bearing OD. The length is the two bearing widths + the spacer ( another 6205 bearing without the cage and balls) - 0.5 or maybe 1mm.? The PCS of M8 studs is a nice fit over the block but needn't be. The bearing outers are clamped axially between the I beam and the plate. This plate is relieved to clear the inner race. Therefore they can be a sliding fit. The inner races are clamped by a screw in the end of the shaft against a shoulder at the prop shaft end. Order is 5205, spacer, 6205, spacer, taperlock hub for pulley, washer, lockwasher, M10 screw. Again should be an interference fit but bcause I am clamping them I left it a tight clearance fit. It was a couple of hours altogether. Shaft is 303 as well. It's what I had. I have a 3/4" bore the other end for the prop shaft. It is cross drilled. Was going to put in a shearpin but I think I'll split it and clamp it solid.? If I had my time back I would have made it longer and gone s7205 2rs both ends with 2 spacer bearings, stainless as well if i can get them. 2 rolling elements would have less friction.? Regards Anthony
On Fri 28 May 2021, 8:07 PM Dan Pfeiffer < dan@...> wrote:
That looks great.? I like the way you used the I-beam section in the assembly along with the angles to give you pitch and yaw adjustment.??? Well done.?? I was going to use a C-channel for my mounting plate but it was not wide enough to accommodate the large belt pulley I needed for my 3:1 ratio.? The big pulley is 60 tooth and relatively heavy (16lbs/7kg) and is a bit of a flywheel.?
I'd like to see more of your bearing housing fabrication.?? I used a 5207 double angular contact bearing and a UCF205-16 flange mount as a pilot bearing on the output shaft of my reduction gear.?? I used a rubber sealed 5207 and made a housing from aluminum.? Not as robust as steel but ZF marine transmissions are aluminum and have to hold similar bearings to take similar loads so I am giving it a try.?
I have a soft mount by having my mounting flanges sit on rubber blocks that sandwich the fiberglass beds of the boat.? The equivalent place would be under your unistrut rails.?
I am at about the same state in my assembly.? Maybe a couple weeks from going in the water.?? I am about to machine the output shaft of my reduction gear unit.?
I am sure you are correct about re-aligning in the water.?
Dan Pfeiffer
?
On 2021-05-26 12:13 pm, julie Lynch wrote:
Hi. I am in the process of building the suggested system.
?24v of leisure batteries 70Ah,?
24v to 230v a.c. inverter,?
230v single to 230v 3 phase variable frequency drive?
and standard 2.2kw 3 phase motor.?
It is going into a Halcyon 23 sailing boat. 84lb thrust, 24v (Bison?) outboard, approx. 1kw as second auxiliary. Found it a bit weak against a headwind on a previous boat, 19ft.
Moored on a swinging mooring in a sparsely populated bay in West Cork, Ireland so very little motoring intended (minutes) so I can absorb the losses of all the electrical conversions. I have a backup so I can accept the increased risk of failure of a component.?Cheap chinese components all. Nothing marine rated.
I wouldn't recommend this to anyone who was intending travelling too far or at all for a primary propulsion system.?
I have milled the motor mount to take a more proven bldc motor if I want to down the line.
I am running a 3 to 1 timing belt reduction to the 2 blade prop that was on the boat. I think it's 12d x 10p inches.
Original 3/4" bronze shaft to homemade bearing housing. 5206 double angular contact bearing for thrust and 6206 to take radial belt load. Spaced apart for radial stiffness. Probably should be using stainless bearings. Next year maybe.
Runs fine on the bench. Won't be in water for another month. I'll document and post it if it is still a success by September.?
Recharge via 270w solar.
Backup power is by Briggs and Stratton 3.5hp former lawnmower and 24v lorry alternator.
Worries:
Motor and bearing assembly is mounted hard on to unistrut rails on stringers. No flexible mounts.
Packing gland is hard mounted on stern tube. Essentially acts as a mid shaft bearing. Alignment has to be perfect! I think I may have to align the motor again when boat is floating.
Don't try this at home, kids.
Yet.
?
Anthony
?
?
?
This is probably a really silly question, but....
?
Is it possible to find a 120V AC motor that can be speed controlled (and maybe even reversed??) for at least a proof of concept on a boat?
?
For those of us that prefer electric motors to gas or diesel engines, but are challenged by the investment of a huge battery bank, wouldn't it be cool if we could run an AC motor off an inverter from whatever battery bank we have handy, and use a generator to supplement - or just run off the generator entirely at first?
?
We've discussed the efficiency gain of running off a higher voltage / lower current.
I'm guessing that there just isn't a suitable way to control and/or reverse an AC motor??
?
John
|
Thanks for the details.? Mine is all on manual mill and lathe as well.? I do have a DRO on the mill which I couldn't function without.?
My main bearing (5207) is clamped between a shoulder on the shaft and a threaded collar clamp on the other end.? The 2nd bearing (UCF205-16) is a pilot bearing that the forward end of the shaft fits in.? Photos are with a test shaft I made in aluminum.? It was only 1.5" dia so the big shoulder isn't there.? The final shaft is from 1.75" 304 SS.? I was going to use 4140 chrome moly as had been suggested but I could not get a good finish on it.? The SS is easier in that regard and cost about the same.? Not as strong but strong enough I think.? Min dia is 1.25 and? I thing it's stronger than what the Thunderstruck unit has and that seems to work.? I should finish turning that this weekend.?
The side mount was to leave room for a diesel gen set.? I hope the 50lb motor hanging off to the side is OK.? I can add a support mount with an isolation block if need be.?? The belt is captive but it is not too difficult to remove the cover.?? I added that to support the pilot bearing that I decided I wanted because of the mass of the drive pulley and to keep the shaft in column.??
Dan Pfeiffer
?
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On 2021-05-29 10:34 am, julie Lynch wrote:
Hi Dan. That's nice work. Your motor being mounted to one side gives excellent access for checking or aligning the arrangement. Your belt is captive though. Someone suggested leaving the spare belt around the end of the shaft ready to in a hurry. I should be able to roll on my 20mm wide HTD8mm in a few seconds if the need arises.?
Bearing block:
I don't have access to CNC machine tools.?
I just have a manual lathe and mill. I had a bar end of 2.5" 303 and I faced and bored it to the bearing OD. The length is the two bearing widths + the spacer ( another 6205 bearing without the cage and balls) - 0.5 or maybe 1mm.?
The PCS of M8 studs is a nice fit over the block but needn't be. The bearing outers are clamped axially between the I beam and the plate. This plate is relieved to clear the inner race. Therefore they can be a sliding fit.
The inner races are clamped by a screw in the end of the shaft against a shoulder at the prop shaft end. Order is 5205, spacer, 6205, spacer, taperlock hub for pulley, washer, lockwasher, M10 screw. Again should be an interference fit but bcause I am clamping them I left it a tight clearance fit. It was a couple of hours altogether. Shaft is 303 as well. It's what I had. I have a 3/4" bore the other end for the prop shaft. It is cross drilled. Was going to put in a shearpin but I think I'll split it and clamp it solid.?
If I had my time back I would have made it longer and gone s7205 2rs both ends with 2 spacer bearings, stainless as well if i can get them. 2 rolling elements would have less friction.?
Regards Anthony
?
On Fri 28 May 2021, 8:07 PM Dan Pfeiffer < dan@...> wrote:
That looks great.? I like the way you used the I-beam section in the assembly along with the angles to give you pitch and yaw adjustment.??? Well done.?? I was going to use a C-channel for my mounting plate but it was not wide enough to accommodate the large belt pulley I needed for my 3:1 ratio.? The big pulley is 60 tooth and relatively heavy (16lbs/7kg) and is a bit of a flywheel.?
I'd like to see more of your bearing housing fabrication.?? I used a 5207 double angular contact bearing and a UCF205-16 flange mount as a pilot bearing on the output shaft of my reduction gear.?? I used a rubber sealed 5207 and made a housing from aluminum.? Not as robust as steel but ZF marine transmissions are aluminum and have to hold similar bearings to take similar loads so I am giving it a try.?
I have a soft mount by having my mounting flanges sit on rubber blocks that sandwich the fiberglass beds of the boat.? The equivalent place would be under your unistrut rails.?
I am at about the same state in my assembly.? Maybe a couple weeks from going in the water.?? I am about to machine the output shaft of my reduction gear unit.?
I am sure you are correct about re-aligning in the water.?
Dan Pfeiffer
?
On 2021-05-26 12:13 pm, julie Lynch wrote:
Hi. I am in the process of building the suggested system.
?24v of leisure batteries 70Ah,?
24v to 230v a.c. inverter,?
230v single to 230v 3 phase variable frequency drive?
and standard 2.2kw 3 phase motor.?
It is going into a Halcyon 23 sailing boat. 84lb thrust, 24v (Bison?) outboard, approx. 1kw as second auxiliary. Found it a bit weak against a headwind on a previous boat, 19ft.
Moored on a swinging mooring in a sparsely populated bay in West Cork, Ireland so very little motoring intended (minutes) so I can absorb the losses of all the electrical conversions. I have a backup so I can accept the increased risk of failure of a component.?Cheap chinese components all. Nothing marine rated.
I wouldn't recommend this to anyone who was intending travelling too far or at all for a primary propulsion system.?
I have milled the motor mount to take a more proven bldc motor if I want to down the line.
I am running a 3 to 1 timing belt reduction to the 2 blade prop that was on the boat. I think it's 12d x 10p inches.
Original 3/4" bronze shaft to homemade bearing housing. 5206 double angular contact bearing for thrust and 6206 to take radial belt load. Spaced apart for radial stiffness. Probably should be using stainless bearings. Next year maybe.
Runs fine on the bench. Won't be in water for another month. I'll document and post it if it is still a success by September.?
Recharge via 270w solar.
Backup power is by Briggs and Stratton 3.5hp former lawnmower and 24v lorry alternator.
Worries:
Motor and bearing assembly is mounted hard on to unistrut rails on stringers. No flexible mounts.
Packing gland is hard mounted on stern tube. Essentially acts as a mid shaft bearing. Alignment has to be perfect! I think I may have to align the motor again when boat is floating.
Don't try this at home, kids.
Yet.
?
Anthony
?
?
?
This is probably a really silly question, but....
?
Is it possible to find a 120V AC motor that can be speed controlled (and maybe even reversed??) for at least a proof of concept on a boat?
?
For those of us that prefer electric motors to gas or diesel engines, but are challenged by the investment of a huge battery bank, wouldn't it be cool if we could run an AC motor off an inverter from whatever battery bank we have handy, and use a generator to supplement - or just run off the generator entirely at first?
?
We've discussed the efficiency gain of running off a higher voltage / lower current.
I'm guessing that there just isn't a suitable way to control and/or reverse an AC motor??
?
John
|
Perhaps what might be a way to do this is use a 220 /240 volt generator run that into a VFD to make 3 phase to run a motor.? You will need to calculate the KW or HP needed then double the size of the drive. An example would be a drive that's good for 5 hp would be able to run a 2.5 hp motor.? I don't know how to calculate gearing or if you would need any.?
On Tue, May 25, 2021 at 10:21 PM, john via groups.io <oak_box@...> wrote:
This is probably a really silly question, but....
Is it possible to find a 120V AC motor that can be speed controlled (and maybe even reversed??) for at least a proof of concept on a boat?
For those of us that prefer electric motors to gas or diesel engines, but are challenged by the investment of a huge battery bank, wouldn't it be cool if we could run an AC motor off an inverter from whatever battery bank we have handy, and use a generator to supplement - or just run off the generator entirely at first?
We've discussed the efficiency gain of running off a higher voltage / lower current. I'm guessing that there just isn't a suitable way to control and/or reverse an AC motor??
John
|
Hi Mike et al., With regard to running a VFD straight off of a generator: Generators are a bit spiky on voltage when they have no load. For instance, I fried the 12v dc power supply for my wifi receiver when I ran the house on a genny during a power cut. The man who supplied the wifi told me that having a 100 Watt bulb on the genny before you connect anything electronic would give it enough drain to let it regulate the voltage properly.? A vfd is rectifying the input ac to a 330V ish DC bus and then chopping that into 3 230v ac phases. It may well be very tolerant of spikes, dumping it through a brake resistor if fitted. Also there is normally a slow start which slowly fills the dc bus at startup. You would have to have some other resistive load on the genny for when load comes off the vfd. ?I wouldn't chance it at sea. But they are so cheap now it might be an interesting experiment on a river. With an outboard handy.? Bit circular though, using petrol to rotate a motor, 20% efficiency, to rotate a generator to produce 230v ac, ~93% efficient to power a VFD to rectify to 330v DC, ~98% to produce 3 phase ac, ~95% to drive a motor, ~87%
to rotate a propshaft. Overall efficiency 15% to the gearbox, about half that of a diesel inboard, all the noise and smell. Only advantages over an ICE inboard, you can use the genny for other stuff when not boating, no winterising and?maintenance is easy, on the bench.
Anthony
On Mon, May 31, 2021 at 3:45 PM Mike hurley via <redwood1957= [email protected]> wrote: Perhaps what might be a way to do this is use a 220 /240 volt generator run that into a VFD to make 3 phase to run a motor.?You will need to calculate the KW or HP needed then double the size of the drive. An example would be a drive that's good for 5 hp would be able to run a 2.5 hp motor.? I don't know how to calculate gearing or if you would need any.? On Tue, May 25, 2021 at 10:21 PM, john via
This is probably a really silly question, but....
Is it possible to find a 120V AC motor that can be speed controlled (and maybe even reversed??) for at least a proof of concept on a boat?
For those of us that prefer electric motors to gas or diesel engines, but are challenged by the investment of a huge battery bank, wouldn't it be cool if we could run an AC motor off an inverter from whatever battery bank we have handy, and use a generator to supplement - or just run off the generator entirely at first?
We've discussed the efficiency gain of running off a higher voltage / lower current. I'm guessing that there just isn't a suitable way to control and/or reverse an AC motor??
John
|
There are several advantages to electric over an ICE:
Quiet - remember how it sounds when you have the sails up and you turn off the engine?
Water Pollution: you don't blow exhaust into the water
Torque at any prop speed:? ?can turn the prop really slow
Trim: position the battery to help trim the boat
Space and positioning:? ?electric motor is usually pretty easy to position and align.? Engine takes up little space?
Caveat Emptor
Not for everyone.? ?If you are cruising on engine for long periods of time ICE is more practical.? If you can't remember to keep batteries charged up then go ICE.
Peter S. Ford
petersford@...
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Hi Mike et al.,
With regard to running a VFD straight off of a generator:
Generators are a bit spiky on voltage when they have no load. For instance, I fried the 12v dc power supply for my wifi receiver when I ran the house on a genny during a power cut. The man who supplied the wifi told me that having a 100 Watt bulb on the
genny before you connect anything electronic would give it enough drain to let it regulate the voltage properly.?
A vfd is rectifying the input ac to a 330V ish DC bus and then chopping that into 3 230v ac phases. It may well be very tolerant of spikes, dumping it through a brake resistor if fitted. Also there is normally a slow start which slowly fills the dc bus
at startup. You would have to have some other resistive load on the genny for when load comes off the vfd.
?I wouldn't chance it at sea. But they are so cheap now it might be an interesting experiment on a river. With an outboard handy.?
Bit circular though, using petrol to rotate a motor, 20% efficiency,
to rotate a generator to produce 230v ac, ~93% efficient
to power a VFD to rectify to 330v DC, ~98%
to produce 3 phase ac, ~95%
to drive a motor, ~87%
to rotate a propshaft.
Overall efficiency 15% to the gearbox, about half that of a diesel inboard, all the noise and smell.
Only advantages over an ICE inboard, you can use the genny for other stuff when not boating, no winterising and?maintenance is easy, on the bench.
Anthony
On Mon, May 31, 2021 at 3:45 PM Mike hurley via
<redwood1957= [email protected]> wrote:
Perhaps what might be a way to do this is use a 220 /240 volt generator run that into a VFD to make 3 phase to run a motor.?
You will need to calculate the KW or HP needed then double the size of the drive. An example would be a drive that's good for 5 hp would be able to run a 2.5 hp motor.?
I don't know how to calculate gearing or if you would need any.?
On Tue, May 25, 2021 at 10:21 PM, john via
This is probably a really silly question, but....
Is it possible to find a 120V AC motor that can be speed controlled (and maybe even reversed??) for at least a proof of concept on a boat?
For those of us that prefer electric motors to gas or diesel engines, but are challenged by the investment of a huge battery bank, wouldn't it be cool if we could run an AC motor off an inverter from whatever battery bank we have handy, and use
a generator to supplement - or just run off the generator entirely at first?
We've discussed the efficiency gain of running off a higher voltage / lower current.
I'm guessing that there just isn't a suitable way to control and/or reverse an AC motor??
John
|
A 3-phase AC motor is easy to put into reverse mode. "Boating by wire", i.e. putting the helm wherever you want and just running a few electrical cables, is easier with an electric motor.
Efficiencies depend on operating point. Especially with a battery, you can run the genny at its optimum operation point, independently what the propulsion motor requires at the moment. There are diesel electric locomotives for a reason.
The disadvantages that I see (having contemplated that by myself): A quiet genny that uses the surrounding water for cooling isn't easy to find for low power applications (i.e. less than 10 to 20 kW).
|
Fischer Panda makes an 11kW/48vdc generator with sound shield and water cooling. Larger sizes from Polar Power.?
|
About $13,000 I think...
?
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On 2021-06-01 5:44 pm, Reuben Trane via groups.io wrote:
Fischer Panda makes an 11kW/48vdc generator with sound shield and water cooling. Larger sizes from Polar Power.?
|
There have been some interesting developements in small lightweight engines in recent years; one of them being further developement of the Wankel motor coupled with a generator. The link is one of a number being developed and a bit of research is needed. This one is liquid cooled and can run on av. gas which I like. No decibel ratings are given and I have no idea of the price. . Another interesting development is the "Two Sided Free piston Linear engine" which can run on CNG gas which is lighter than air or petrol. I imagine it would be very quiet and is very light. . I don't imagine that any of these are cheap, imerging technology never is.
Peter
--
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|
There is also promising work on coinjecting hydrogen with diesel fuel giving slightly higher performance and considerably lower emissions. Watch this space closely - it may be the way of the future/save ICE tech from being killed off prematurely. As it is, anyone trained and working as an ICE engineer or technician must be worried about their medium term job prospects right about now ...
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On 2 Jun 2021, at 10:23, peter snowdon via groups.io <petersnowdon@...> wrote:
?There have been some interesting developements in small lightweight engines in recent years; one of them being further developement of the Wankel motor coupled with a generator. The link is one of a number being developed and a bit of research is needed. This one is liquid cooled and can run on av. gas which I like. No decibel ratings are given and I have no idea of the price. . Another interesting development is the "Two Sided Free piston Linear engine" which can run on CNG gas which is lighter than air or petrol. I imagine it would be very quiet and is very light. . I don't imagine that any of these are cheap, imerging technology never is.
Peter
--
This email has been checked for viruses by Avast antivirus software.
|
It is good and right that as many hydrocarbon-fueled ICE technologies as possible are "killed off", asap. There are always opportunities for skilled mechanics in other fields but these very technologies create the demand for petroleum fuels that are ruining our planet.
|
The whole world is laughing at us. ?Petroleum fuels are not ruining the planet, the number of carbon units are ruining our planet. ?Soon the number of carbon units will double and 10 years after that they will double again. If you really care about the planet then depart it and save the stress that you are personally putting on it.
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It is good and right that as many hydrocarbon-fueled ICE technologies as possible are "killed off", asap. There are always opportunities for skilled mechanics in other fields but these very technologies create the demand for petroleum fuels that are ruining our planet.
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Hi?
I am the moderator of this group.
Please keep in mind that it is meant for discussion and tips about electric boats and boating.
There are lots of other places and forums where the purpose is to discuss and debate what is happening on our planet.?
I respectfully request that this thread be kept to the topic at hand: “Powering with a 120V AC motor”
Thanks
Jeff Butler
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The whole world is laughing at us. ?Petroleum fuels are not ruining the planet, the number of carbon units are ruining our planet. ?Soon the number of carbon units will double and 10 years after that they will double again. If you really care about the planet then depart it and save the stress that you are personally putting on it.
It is good and right that as many hydrocarbon-fueled ICE technologies as possible are "killed off", asap. There are always opportunities for skilled mechanics in other fields but these very technologies create the demand for petroleum fuels that are ruining our planet.
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Frequency drives are taking over the commercial AC motors market.? Convenience stores here in Chicago are replacing their motor 'starters' (typically a simple contactor w/control circuit arrangement) with variable frequency drives on 3-phase HVAC fans, compressors, pumps, etc.. The CTA (commuter trains aka 'Elevated' trains) are replacing their trains' older brushed DC motors with three phase AC motors and inverters, yet still running the 'third rail' on 600VDC. They are not doing this for no reason.?It's being done for _efficiency_ and maintainability.?
Again, this is not only my opinion, but 7-11, Chicago Transit Authority, etc. deciding this.? An estimated savings of 30% on the electric bill is (I'm told) typical of switching from straight 3-phase AC (on/off type 'sinewave' control) to VFDs with complex control waveforms used with/for standard inexpensive 3-phase squirrel cage induction motors.? (Note: three phase motors are inherently more efficient to start with.)? There's a LOT of control theory developed?at electrical engineering schools over the last 50 years that got us here.? I must admit I've been confused why boaters would even look at these oddball boutique motor types when standard off-the-shelf parts are now available.
Think about it.? In food processing they need motors you can literally hose down for cleaning. And they need a spare handy so the line can be brought back running ASAP if something breaks. _And_ they need it to be cost effective.? _And_ efficient so they keep the electric bill down.? Someone want to debate the virtues of specialty 'Marine' rated devices against that?? Be my guest.? The control and safety side of these systems are well understood by most competent industrial maintenance techs too.? Short ckt protection=>VFD=>overload protection=>motor.? Done.? Off the shelf parts.? Industrial grade.
Dave
On Monday, May 31, 2021, 09:45:47 AM CDT, Mike hurley via groups.io <redwood1957@...> wrote:
Perhaps what might be a way to do this is use a 220 /240 volt generator run that into a VFD to make 3 phase to run a motor.? You will need to calculate the KW or HP needed then double the size of the drive. An example would be a drive that's good for 5 hp would be able to run a 2.5 hp motor.? I don't know how to calculate gearing or if you would need any.?
On Tue, May 25, 2021 at 10:21 PM, john via groups.io <oak_box@...> wrote:
This is probably a really silly question, but....
Is it possible to find a 120V AC motor that can be speed controlled (and maybe even reversed??) for at least a proof of concept on a boat?
For those of us that prefer electric motors to gas or diesel engines, but are challenged by the investment of a huge battery bank, wouldn't it be cool if we could run an AC motor off an inverter from whatever battery bank we have handy, and use a generator to supplement - or just run off the generator entirely at first?
We've discussed the efficiency gain of running off a higher voltage / lower current. I'm guessing that there just isn't a suitable way to control and/or reverse an AC motor??
John
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I agree with Dave. Vfd and induction motor is only very slightly less efficient than PMAC/ BLDC. That is the slippage required to magnetize the rotor. No need for overload between vfd and motor. The motors rated current is programmed in and vfd acts as a virtual thermal overload. Now what is really needed by this community is a VFD that can take 24 or 48volts and buck boost it to the vfd bus dc voltage 600v typically for 400v motor. If you cut out the need to turn 12v or 24v dc into 230v single phase a.c. and then rectify it to bus voltage you have removed 2 processes and the associated losses. Anthony
Frequency drives are taking over the commercial AC motors market.? Convenience stores here in Chicago are replacing their motor 'starters' (typically a simple contactor w/control circuit arrangement) with variable frequency drives on 3-phase HVAC fans, compressors, pumps, etc.. The CTA (commuter trains aka 'Elevated' trains) are replacing their trains' older brushed DC motors with three phase AC motors and inverters, yet still running the 'third rail' on 600VDC. They are not doing this for no reason.?It's being done for _efficiency_ and maintainability.?
Again, this is not only my opinion, but 7-11, Chicago Transit Authority, etc. deciding this.? An estimated savings of 30% on the electric bill is (I'm told) typical of switching from straight 3-phase AC (on/off type 'sinewave' control) to VFDs with complex control waveforms used with/for standard inexpensive 3-phase squirrel cage induction motors.? (Note: three phase motors are inherently more efficient to start with.)? There's a LOT of control theory developed?at electrical engineering schools over the last 50 years that got us here.? I must admit I've been confused why boaters would even look at these oddball boutique motor types when standard off-the-shelf parts are now available.
Think about it.? In food processing they need motors you can literally hose down for cleaning. And they need a spare handy so the line can be brought back running ASAP if something breaks. _And_ they need it to be cost effective.? _And_ efficient so they keep the electric bill down.? Someone want to debate the virtues of specialty 'Marine' rated devices against that?? Be my guest.? The control and safety side of these systems are well understood by most competent industrial maintenance techs too.? Short ckt protection=>VFD=>overload protection=>motor.? Done.? Off the shelf parts.? Industrial grade.
Dave
On Monday, May 31, 2021, 09:45:47 AM CDT, Mike hurley via <redwood1957= [email protected]> wrote:
Perhaps what might be a way to do this is use a 220 /240 volt generator run that into a VFD to make 3 phase to run a motor.? You will need to calculate the KW or HP needed then double the size of the drive. An example would be a drive that's good for 5 hp would be able to run a 2.5 hp motor.? I don't know how to calculate gearing or if you would need any.? On Tue, May 25, 2021 at 10:21 PM, john via
This is probably a really silly question, but....
Is it possible to find a 120V AC motor that can be speed controlled (and maybe even reversed??) for at least a proof of concept on a boat?
For those of us that prefer electric motors to gas or diesel engines, but are challenged by the investment of a huge battery bank, wouldn't it be cool if we could run an AC motor off an inverter from whatever battery bank we have handy, and use a generator to supplement - or just run off the generator entirely at first?
We've discussed the efficiency gain of running off a higher voltage / lower current. I'm guessing that there just isn't a suitable way to control and/or reverse an AC motor??
John
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Reuben Trane
Randy Cain
CaptainJohn49