Has anyone any experience or knowledge to offer inn respect of any of the following?
Given that a high voltage energy source, alternator or PV array, is likely to suffer fewer losses due to conductor heating than a high current system of the same capacity I find myself wondering if there is anything in actively matching supply characteristics to the desired load.
This seems particularly pertinent with respect to wind driven alternators, which as I understand it, are usually a compromise.
Please correct me if I am wrong....
1. If an alternator has sufficient windings to produce a usable voltage at low speed then it will also have a high impedance which will prevent it from delivering that voltage at higher currents when energy is potentially available.
This would also result in overspend in any wind turbine that had no other form of limiting.
2. An alternator with fewer and bigger windings will make use of high available energy situations but fail to produce any usable power, due to lack of voltage, at lower speeds.
If both the above are assumptions are correct then the ideal would be to have a low current system all the time but vary the voltage depending on the power available, the problem being that is the exact opposite of what is required for just about any useful load I can think of.
Whilst musing on this point and thinking about switchable alternator configurations it occurred to me that it should be possible to create a variable voltage and current converter. The ideal situation would be to take a constant current from the source whilst allowing the voltage to float and deliver a controlled, lower, voltage to the load whilst allowing the current to float based on the impedance of the load. (The latter half being essentially a standard charge controller)
I am not suggesting that anything would ‘make' power, in fact any such circuit or device would have losses and therefore use power and could operate only if some arbitrary level of energy was present, but there are potential options I think.
Anyone care to comment on any of the following:-
Transformer with multiple primary tapings.
Variable autotransformer (Variac)
Buck converter circuit.
Buck/Boost converter circuit.
Conversion using capacitors and high frequency PWM
Chopping power supply with wide input voltage range and variable output.
I had a quick look around the web and found two interesting things …
A well designed buck circuit can be very efficient, 95% or better.
MPPT modules exist to maximise solar panel performance, these must use a comparable strategy.
Lastly, and far more simply I might add, how about an alternator stator divided into at least 4 parts which could be switched from series to series/parallel to parallel.
This would give 3 potential load and speed curves that a machine could utilise based on the current wind condition (Level of energy available)
Thoughts anyone …. Has anyone tried any of this?
Al