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EE595S: Class Lecture Notes

Chapter 15: Brushless DC Motor Drives

S.D. Sudhoff

Fall 2005

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Fall 2005 EE595S Electric Drive Systems 2

15.1 Architecture

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15.2 Topology

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15.3 Equivalence of VSI Schemes

to Idealized Source

180 VSI

Duty Cycle Modulation

Sine-Triangle Modulation

Sine-Triangle Modulation (with 3rd) Space-Vector Modulation

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Fall 2005 EE595S Electric Drive Systems 5

180 VSI Operation

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Fall 2005 EE595S Electric Drive Systems 6

180 VSI Operation

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Fall 2005 EE595S Electric Drive Systems 7

180 VSI Operation

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180 VSI Operation

Comparing the two figures

(15.3-1)

Now recall

(15.3-2)

(15.3-3)

hrc +=

dc

c

qsvv

2=

0=cds

v

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Fall 2005 EE595S Electric Drive Systems 9

180 VSI Operation

Using the frame-to-frame transformation

(15.3-4)

(15.3-5)

Thus

(15.3-6)

(15.3-7)

hdcrqs vv cos2=

hdcrds

vv

sin2=

dcs vv

2

2

1=

hv =

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180 VSI Operation

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Duty Cycle Modulation

In this case

(15.3-8) (15.3-9)

Thus

(15.3-10)

(15.3-11)

So

(15.3-12)

(15.3-7)

dccqs vdv 2=0=c

dsv

hdcrqs vdv cos2=

hdcrds

vdv

sin2=

dcs vdv2

21=

hv =

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Duty Cycle Modulation

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Sine-Triangle Modulation

In this case, converter angle calculated as

(15.3-13)

Now recall

(15.3-14)

(15.3-15)

(15.3-16)

vrc +=

>

+=d

dddf

d

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Sine-Triangle Modulation

Converting to the rotor reference frame

(15.3-17)

(15.3-18)

>

=1cos)(

1cos

221

ddfv

ddvv

vdc

vdcrqs

>

= 1sin)(

1sin

2 2

1

ddfv

ddv

vvdc

vdcrds

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Sine-Triangle Modulation

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Sine Triangle Modulation

with 3rdHarmonic Injection

Following our earlier work, we will have

(15.3-19)

(15.3-20)

3/20cos21 = dvdv vdcrqs

3/20sin21 = dvdv vdc

rds

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Space Vector Modulation

In this case we have

(15.3-21)

(15.3-22)

(15.3-23)