Essentials of DC Motor, Brushless DC Motor, and PMSM
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陳正虎 成大馬達科技研究中心 http://emotors.ncku.edu.tw/motor_learn/
Essentials of DC Motor, Brushless DC Motor, and PMSM
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陳正虎william@ckmail.ncku.edu.tw
(06)2757575 分機 61130
陳正虎 成大馬達科技研究中心 http://emotors.ncku.edu.tw/motor_learn/
Outline
Fundamental Concepts of DC motors, Brushless DC motors and PMSMsUnderstanding of Kt and Ke in DC motors, Brushless DC motors and PMSMs.How to determine the SOA (Safe Operating Area) of DC motors, Brushless DC motors and PMSMs.Function and Installation of Position Sensor (Hall Effect Sensor).
陳正虎 成大馬達科技研究中心 http://emotors.ncku.edu.tw/motor_learn/
Practical Configuration
The torque or voltage ripples can be reducedas the number of the commutators are increased.
陳正虎 成大馬達科技研究中心 http://emotors.ncku.edu.tw/motor_learn/
Dynamic Model
aT a a e r a
e l
diV I R K Ldt
T T J B
ω
α ω
= + +
− = +
陳正虎 成大馬達科技研究中心 http://emotors.ncku.edu.tw/motor_learn/
Steady State Model
T a a e rV I R K ω= +
e t aT K I= t eif K K=
2t T t
ra a
K V KTR R
ω= −
陳正虎 成大馬達科技研究中心 http://emotors.ncku.edu.tw/motor_learn/
Perfect Energy-Conversion Process
e r a aT E Iω =
In ideal case, the electrical power was perfectly transferred intomechanical output power, that is
1
te r t a a a
e e
t
e
kET k I E Ik k
kk
ω = ⋅ =
⇒ =
Is it possible that Kt/Ke greater than 1?
陳正虎 成大馬達科技研究中心 http://emotors.ncku.edu.tw/motor_learn/
T-N Curve2
t T te r
a a
K V KTR R
ω= −max
t T
a
K VTR
=
_ maxT
rt
VK
ω =
There is a trade-off betweenhigh torque and high speed.
陳正虎 成大馬達科技研究中心 http://emotors.ncku.edu.tw/motor_learn/
Safe Operating Area
Voltage: Maximum SpeedCurrent: Maximum TorqueRated Power: Thermal Dissipation
陳正虎 成大馬達科技研究中心 http://emotors.ncku.edu.tw/motor_learn/
Waveform of Phase and L-L BEMF
BEMF Measured from the same motor.
Sinusoidal or Trapezoidal??
陳正虎 成大馬達科技研究中心 http://emotors.ncku.edu.tw/motor_learn/
Power Conversion of Multiphase System
rmsrms
crmscrmsbrmsbrmsarmsarmsm
IEIEIEIET
3______
=
++=ω
•In ideal case, the electrical power was perfectly transformedinto mechanical output power, that is
陳正虎 成大馬達科技研究中心 http://emotors.ncku.edu.tw/motor_learn/
Phase U
Phase V
Phase W
UE
VE
WE
ui
back EMF
Current
Torque VU WU WV UV UW VW VU
(integrated three-phasecurrent)
i
vi
wi
2wvu iii
i++
=
Benefits:1. Phase Control2. Improve Kt3. Improve Dynamics
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