Here's a look at my 1st and 2nd generation 'Power Wheel' controllers.  The 1st generation prototype is on the left and the 2nd generation is on the right.  The maximum overall specs are 200 V and 1350 Amps (1080 A for 2nd gen.).  As far as I know, the symmetrical design is unique in this market.  Usually, controllers have MOSFETs arranged in 'straight-bus' fashion.  I wanted to explore a new symmetrical design approach that enabled fair and equal treatment for all of the MOSFETs.

 

As you can see, the above two prototypes are circular in design.  The circularity offers symmetrical and balanced treatment of drive control, high-current distribution among the power switches (MOSFETs) and even distribution and dissipation of heat.  It is also very easy to service, should the need arise.

 

All MOSFETs are mounted evenly spaced around the edge of one of the aluminum discs (internally in the 2nd gen.).  Everything about the design is perfectly symmetrical and balanced.  For high-power applications, this helps ensure equal treatment for all of the power MOSFETs.

 

The current limiting is adjustable over range.  Interestingly, I am finding that the performance is just fine at a conservative 400 Amp setting.  Even though the total MOSFET current rating is 1350 A for the first generation 'Power Wheel' and 1080 A for the second generation.  By the way, no controller can be operated at the maximum total MOSFET rating.  Therefore, the maximum safe operating current for either of these controllers is actually 600 A or 500 A respectively.  However, there is more to it than this.  See my article on Electric Vehicle Controller Operation.

 

The 2nd gen. controller is smaller and much lighter than the 1st gen. controller or the original Curtis controller.  The 2nd gen. controller was placed in service early in August 2008 and seems to be very solid.

 

Like most controllers, I have a 'watch-dog' circuit that disables the controller and cuts power if the throttle potentiometer becomes open or disconnected.  I do not have over-temperature protection because these MOSFETs become barely warm.  Even so, future plans include a thermal cutoff device that monitors the case temperature of one of the MOSFETs.

 

The pre-production, fully enclosed, Power Wheel X16 is shown below.

 

 

Pre-production 'Power Wheel' shown above. Patent Pending

EVhelp EVH-PWX16 - 144V @ 500 A 

 

 

The 1st generation Power Wheel details were revealed in Power Electronics Technology Magazine. Click here!

 

- Mark