From: me@here.edu   
      
   "Johny B Good"  wrote in message   
   news:op.v4zrdpnhkd9x7s@fred...   
   >   
   >  Which losses also apply to the dynamo.   
   >   
   >  However, a further improvement in efficiency can be obtained by using a   
   > permanent magnet based rotor and using a switching regulator to   
   > efficiently convert the varying (with speed) output voltage to the desired   
   > DC output voltage.   
   >   
   >  This principle is used in the "inverter" based generator sets such as the   
   > Honda EU3000i with its "eco throttle" feature where the DC output is used   
   > to power the 50/60Hz 230/120 volt inverter module.   
   >   
   >  Whilst the inverter based genset designs might seem to have introduced   
   > additional losses (most notably that of the inverter module), the   
   > efficiency difference is insignificant compared to the two benefits   
   > conferred which are:   
   >   
   > 1) Decoupling of generator speed from the AC output frequency which allows   
   > engine speed to be used as the main form of output power regulation when   
   > the eco throttle feature is enabled.   
   >   
   > 2) Decoupling of reactive loads (in particular, leading currents due to   
   > excess capacitance) which can adversely effect voltage regulation in the   
   > classic (cheaper) AC generator based genset designs. In fact it this   
   > 'feature' that makes them so unsuitable for powering Personal Computers   
   > (especially when protected by an in line UPS).   
   >   
   >  The output voltage regulation of a switching sinewave inverter remains   
   > totally unaffected (within defined limits) by such reactive loads. For   
   > example, a cheap 2.8KVA genset I once owned, would, on its 230v regulated   
   > output setting, overvolt to 280v when connected to a 4.7 microFarad PF   
   > correction capacitor borrowed from a 20W fluorescent light fitting. An   
   > inverter based genset would suffer no such deficiency.   
   >   
   >   
   > --   
   > Regards JB Good   
      
   I think even just adding a rotor position sensor (simple hall effect reading   
   the rotor poles just like in a PC brushless muffin fan) and replacing the   
   regular diodes with MOSFETs would enable synchronous rectification and get   
   rid of the diode forward drop.  The fun part here is that the alternator   
   would also try to run as a BLDC motor when the engine speed dropped too low   
   so it would need a circuit to prevent it.   
      
   BTW I did not know how much was lost in the carbon brushes of the dynamo, I   
   just know I have a "3 bobbin" (cut-in/out, current, voltage) 12v mechanical   
   voltage regulator in front of me that I plan to use on an externally   
   regulated Chrysler/Bosch alternator to make a rotary 2 stage battery   
   charger, not efficient, but an interesting project nonetheless.   
      
   I still like the Toyota hybrid method, no alternator, just a PM rotor   
   motor/generator (MG1) and a regulated DC-DC converter for 12v battery   
   charging.  It is kind of an inverter generator integrated into a car.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)