Renesas H8S/2635 Manual descargar pdf (Pagina 12)

Fig. 3.2-1. Basic schematics of brushless motor.

The basic schematic of a brushless motor is shown on the picture 3.2.1. First of all, brushless

motors don't have windings on the rotor. The meaning of this is that here the rotating part is

permanent magnet and the windings are placed on the stator poles. Additionally for proper

functioning we need something what can automatically reverse the current. This can be

achieved in two different ways. First is a mechanical approach, where we can use a cam-

operated reversing switch. Second possibility is to use an electronic amplifier which allows us to

do the commutation in response to low-level signals from an optical or hall-effect sensor. The

general conclusion of above is that we can't just connect our motor to a current source, because

the current in external circuit must be reversed at strict defined position of the rotor. This last

requirement can be very good solved by the use of some microcontroller  for example

H8S/2638 described in the next chapter.

Second thing which is important to understand brushless motors is a placement of windings.

Assuming that we have three phase design motor, we can connect them in two ways. First is

         In both cases the partial

windings are shifted by 120

. Both arrangements can be seen on the following picture:

Fig. 3.2-2. Windings in brushless motor.

1 2 ... 7 8 9 10 11 12 13 14 15 16 17 ... 91 92

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Renesas H8S/2635 Manual Pagina 12