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2 phase linear and torque motors


Joachim
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Hello,

 

Is it possible to run linear motors (u shape) or torque motors which do have only 2 phases? I'm used to work with the Geobrick-lv which is able to run 2 phase motors

( 2phase steppers working fine also 3 phase motors) so it should be a mix of the 2 modes ( stepper and 3 phase brushless)

 

Any idea or tipp?

 

Thanks and Best regards

 

 

Joachim

 

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The Geo Brick LV has 4 half bridges per motor in its power stage, which can be organized as 2 full (H) bridges for 2-phase motors with electrically independent phases. Alternately, you can use 3 of the half bridges for 3-phase motors that are Y or Delta wound.

 

Most servo amplifiers (such as our higher voltage Geo Brick) have only 3 half bridges per motor, so you cannot drive 2-phase motors while keeping the phases independent. However, it is possible to run them with the phases connected. You can connect one phase between the U and V phase outputs, and the other phase between the V and W phase outputs. This has been done successfully with, for example, the Swiss Etel 2-phase brushless servo motors. The disadvantage of this technique is that your effective bus voltage is reduced by 30% compared to independent phases. (You can use only 1/sqrt(2) of the supply voltage.)

 

In PMAC, the issues of 2-phase versus 3-phase motors and stepper versus servo motors are independent questions. The number of phases is dealt with by the power-stage wiring and the value of Ixx72 (1/4 or 1/3 of a cycle). The issue of stepper versus servo (really open-loop versus closed loop control) is dealt with by selecting simulated versus real feedback. However, the vast majority of stepper motors are 2-phase, and the vast majority of servo motors are 3-phase, so these issues sometimes get confused.

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The Geo Brick LV has 4 half bridges per motor in its power stage, which can be organized as 2 full (H) bridges for 2-phase motors with electrically independent phases. Alternately, you can use 3 of the half bridges for 3-phase motors that are Y or Delta wound.

 

Most servo amplifiers (such as our higher voltage Geo Brick) have only 3 half bridges per motor, so you cannot drive 2-phase motors while keeping the phases independent. However, it is possible to run them with the phases connected. You can connect one phase between the U and V phase outputs, and the other phase between the V and W phase outputs. This has been done successfully with, for example, the Swiss Etel 2-phase brushless servo motors. The disadvantage of this technique is that your effective bus voltage is reduced by 30% compared to independent phases. (You can use only 1/sqrt(2) of the supply voltage.)

 

In PMAC, the issues of 2-phase versus 3-phase motors and stepper versus servo motors are independent questions. The number of phases is dealt with by the power-stage wiring and the value of Ixx72 (1/4 or 1/3 of a cycle). The issue of stepper versus servo (really open-loop versus closed loop control) is dealt with by selecting simulated versus real feedback. However, the vast majority of stepper motors are 2-phase, and the vast majority of servo motors are 3-phase, so these issues sometimes get confused.

 

Thanks,

 

So if i understand right, it' s a Yes. I can configure the geobrick-lv as i' m used to do with a 3phase motor, just change ixx72.

Great if it works, we see great potential selling the geobrick with our airbearing rotary stage

Best regards

 

Joachim

 

 

 

 

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