AC/DC

GA John. Well put

You beat me to it again!

The weight of the inverter being saved also will compensate for the slightly thicker wiring needed at the lower voltage for the same power output on a DC system.

Also, the extra complexity of such an inverter will also reduce the MTBF unnecessarily and make more service problems possible....as well as killing a rider or two from time to time in the rain!!! Thicker insulation, more ULA certificates to get etc etc etc....

You cannot run a 200V AC motor directly off any std. power inverter.You can certainly run it on a std VFD drive with a DC-DC converter of 12-310VDC.It works fine-I have tried it.Unfortunately the DC-DC converter is expensive & bulky.Recommend try the Brushless DC hub drives for your bikes.There are enough in the market and please use 24V or 36V as input. The battery needs to be sealed & maintenance free.Car batteries are generally not!

Keep in mind the I squared R losses are much less at higher voltages. Doubling the voltage cuts your wire losses to one quarter. Using a high voltage may well result in reduced losses that more than make up for any losses in a DC-DC converter or VFD. As for the safety of 220V AC in a bike, the problem is no worse than having 800 volts in the hybrid cars. as long as the electrical system is totally floating, with fuses in both supply leads, there is no shock hazard. A person would have to touch both supply and return lines to get shocked. But if there is a residual current device placed on the output of the AC power suppl, that should take care of any concerns about shock hazards. If you decide to ttry th einverter approach, use a high frequency switch mode type not an older iron core based design.

Go with the DC motor as it will have a higher efficiency than the AC induction motor. Be sure to use a DC motor with a permanent magnet field to aid the efficiency.

The AC motor can have high rotor losses which reduces the efficiency. The power inverter also does not have 100% efficiency, so that will also add to the reduction in overall efficiency. To control speed, use a duty cycle controller directly off the battery for maximum efficiency. A high current power transistor, or maybe several in parallel, and a controllable one-shot multivibrator driven by an oscillator makes a dandy duty cycle controller. This can be done with one 556 integrated circuit. A current driver stage between the multivibrator and the power transistor/s is also required.

Any loss in efficiency means less Miles Per Charge, so keep it high !

Any rebuttals or agreements from anyone ?

Ideally DC DC sytem is the best option. No inverter and loss on inverter power consumption.

If the DC motor can be doubled to generate DC when breaking or going down on slope then you can have addional energy . This is there in all Modern Hybrid vehicles.

Further DC motor can take a better load when you start frrrom Zero and acclerate. Only Maintenance of DC motor may be bit costlier.

Otherwise use good Sine wave inverter and convert to AC and use AC motor.

A modern DC motor should not have brushes, so I would guess that maintenance is about the same then as an AC motor.

Where I am totally at sea with is with regard to regenerative braking and Brushless DC motors.

My brain tells me that it should be possible, but I cannot quite picture the "HOW?" exactly.....maybe someone else with better knowledge could comment here....

The bike will have a smaller motor attached to the front wheel, which has brushes, attached to the battery, and so, charging the battery while moving

Totally inefficient I feel, but I appreciate the thought!

Brushless motors MUST be the only way to go, less wearing parts and less resistance to movement.

Also I just remembered, the motor that I had most experience with (Brushless of course) up to a few years ago used Dynamic braking to stop, which means that it works fine as a generator too!!!! otherwise dynamic braking would not have worked at all!!FANTASTIC!!!