mechatronics drives (azionamenti ). mechatronics pwm pwm modulation (pulse width modulation)

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Drives(Azionamenti )

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PWMPWMModulation (Pulse Width Modulation)

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AC brushless drive

[velocita’] [accelerazione]

oscillatore

Sincos encoder o

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50 o 60Hz

Tensione DC bus letta

f0 = 256 frete

PI

PI

Regenerative

Breaking(Recupero

in rete)

1 sinusoid cover 256 memory locations

[acc][vel]

[vel]

Sinusoid in phase with line voltage and amplitude-modulatedwith DC-bus voltage error

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Control Strategies

The Feed-Forward (open loop) is used to provide position, velocity, current profiles, to be followed by the PID (closed loop),

…so to avoid to load the integral action,

…so that I can keep it low and have high dynamics

Feed Forward and PID

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Control Strategies (cont’d)

positionvelocityacceleration

Higher bandwidths

Feed Forward and PID

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Control Strategies (cont’d)

Vector Control (VC) (Controllo ad Orientamento di Campo o

Vettoriale)

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Control Strategies (cont’d)

Vector Control (VC)

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Control Strategies (con’d)

Iq

Id

Ia

Ib

Ic

Experimentally we would see… :

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…and indeed we actually see:

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and:

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Clark & Park Transform

It’s the matrix T that transforms from 3 to 2* vectors and from fixed to rotary reference system.

* Actually 3 currents id, iq and i0, remains, where i0 is the neutral wire (neutro) current (if there’s one).