5 Electric Motor

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ME20013 Systems and Control

5. ELECTRIC MOTOR POSITION CONTROL

CASE STUDY

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DC Motor 

Encoder 

Power amplifier 

PIC Microcontroller 

Inertial load

Encoder interface

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Incremental optical encoder 

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Incremental optical encoder 

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iRev   =−

ω=+   JTT dm

)1s(s

K

u   +τ=

θ

If the voltage and torque disturbances are zero:

BK

1K  =

2

BK

JR=τWhere:

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The controller structure is called a derivative feedback or velocity

feedback controller. The controller gains are:

•Proportional gain, kp

•Velocity gain, kd

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τ+τ

++

τ=

θ

Kk

s)Kk1(

s

/Kk

r  pd2

p

Closed loop transfer function:

2nn

2

2n

s2s

k

r    ω+ςω+

ω=

θ

Compare with standard form for second order lag:

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