RE: [CAD_CAM_EDM_DRO] Re: Electronics gurus please help

I count 4 mosfets not 6 for a unipolar drive, did I miss something? And,
because there are half the parts and no high side drivers involved, I would
say that a unipolar drive is much simpler. I also don't understand why the
voltages would be different.

Scott

-----Original Message-----
From: mariss92705 [mailto:mariss92705@...]
Sent: Wednesday, September 11, 2002 12:59 PM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: [CAD_CAM_EDM_DRO] Re: Electronics gurus please help


Hi,

It takes 6 power transistors and 6 high speed rectifiers to build a
unipolar "chopper", it takes 8 power transistors and 8 high speed
rectifiers to make a bipolar (full bridge) one.

The power rectifiers are not across the power transistors in the
unipolar drive. If MOSFETs are used in a bipolar drive, the
rectifiers are included in the transistors.

The power transistors "see" twice the power supply voltage in a
unipolar drive. In a bipolar drive, the maximum voltage "seen" by the
power transistors is equal to the supply voltage.

The performance of a unipolar drive is about equal to a bipolar drive
running a motor in a half-winding connection.

A bipolar drive is prefered because it is simpler (when MOSFETs are
used) and the circuit voltages are lower.

Mariss

--- In CAD_CAM_EDM_DRO@y..., Vajk Fekete <vajk.fekete@o...> wrote:
>
> question1: is a chopper unipolar driver much worse than a chopper
bipolar drive?
>



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