Download 1. Design principle

2016 China International Conference on Electricity Distribution (CICED 2016)
Xi’an, 10-13 Aug, 2016
Design of the New Motor Operating Mechanism for 40.5kV Vacuum Circuit
Breaker
Yao Zheng, Jianyuan Xu, Kejian Shi, He Bai
(School of Electrical Engineering, Shenyang University of Technology, Shenyang, 110870, China)
Abstract:
Based on mechanical load characteristics of opening and closing operations of 40.5kV vacuum circuit
breaker, a new type of permanent magnet brushless DC motor operating mechanism is designed. The
main structure size of the drive motor is calculated. By analyzing the performance of the same volume
motor under different winding wire diameter and number of turns, the scheme of winding wire diameter
and turns-more output torque, faster motor rotational speed, higher power density-is determined. The
overall design of the drive motor is completed. The mathematical model of the motor is established with
finite element theory. The dynamic behaviours of the motor angular displacement and output torque is
calculated. Compared with the pre-existing motor operating mechanism, the volume of new drive motor is
reduced by 23%. Meanwhile, the average output torque and rotational speed can be increased by 53.4 Nm
and 38 rpm respectively.
1.
Design principle
According to the working principle of motor operating mechanism of 40.5kV vacuum circuit breaker, the
average counter-force of the operating mechanism load is 88 Nm by numerical calculation.
1.1
Main structural parameters of the drive moter
The main dimensions of the drive motor is the armature diameter Di1 and the armature length lef and its
computation formula is the formula (1)[1]:
Di21lef 
4Te max  104
(1)
2πBδ A
The opening and closing operations time of 40.5kV vacuum circuit breaker is tens of milliseconds. The
drive motor runing only in starting and braking phase, the temperature problem is ignored when the motor is
designed, so the high electrical load and magentic load can be used. In this design, the electrical load A is
120A/mm, and the magentic load Bδ is 0.9T. The biggest computing electromagnetic torque Temax is 264Nm, 3
times of the average counter-force of the operating mechanism load. The length-diameter ratio lef/Di1 is 2.
According to the above parameters, the diameter and length of motor stator is calculated. The main structural
parameters of the drive moter are shown in Table 1. Compared with the earlier developed motor by research
group[2], the volume of new drive motor is reduced by 23%.
Table 1 Main Structural Parameters of the Drive Moter
Size of the Stator (mm)
Size of the Stator (mm)
The New Motor
The Pre-existing Motor
1.2
Φ158×210
Φ176×220
Φ97×210
Φ104×220
Effective Volume (cm3)
4117.4
5352.3
The determination of winding wire diameter and turns
When the limited slot fill factor is certain (generally 75%), the winding wire diameter is inversely
proportional to the winding turns. The larger wire diameter, the smaller winding resistance of per unit length.
The more number of the wingding turns, the greater the winding self-induction. Therefore, the cooperative
scheme of winding wire diameter and turns is one of the key factors in the motor dynamic behaviour. Under the
condition of other parameters determined, taking the circuit breaker closing operation in 200V control voltage as
a example, 4 diffirent motor schemes from Table 2 are designed and simulated, the results shown in Figure 1.
As seen in the Table 2 and Figure 1: the angular displacement of motor is 75° when the circuit breaker
closing operation is completed. The average output torque and average rotational speed of the drive motor with
Scheme 1 is 376.9Nm and 272rpm respectively. The output power is the largest and the power density is the
highest. The Scheme 1, therefore, is determined as the final motor design selection. The overall design of the
drive motor is completed.
CICED2016
Session 7
Paper No. FP1118
Page1/2
2016 China International Conference on Electricity Distribution (CICED 2016)
Xi’an, 10-13 Aug, 2016
Table 2 Different Winding Wire Diameter and Turns Motors and the Simulated Results
Wire Diameter Winding
The Average Output
The Average Rotational
The Average Output
(mm)
Turns
Torque (N·m)
Speed (rpm)
Power (kW)
1.35
24
376.9
272
10.74
1.3
25
330.5
245
0.85
1.25
Angular Displacement(Degree)
Scheme 3
27
318.6
231
80
0.79
600
Scheme 1
Scheme 1
70
500
60
Scheme 2
Scheme 2
Torque(N.m)
Scheme 1
Scheme 2
Scheme 3
50
40
30
400
300
200
20
Scheme 3
100
10
0
0
10
20
30
40
50
0
60
0
t(ms)
10
20
30
40
50
60
t(ms)
(a) The angular displacement of the drive motors
(b) The output torque of the drive motors
Figure 1 The simulated results of the angular displacement and output torque
600
80
The new motor
70
500
The new motor
60
Torque(N.m)
Angular Displacement(Degree)
Compared with the pre-existing motor operating mechanism in Figure 2, the average output torque of the
pre-existing motor is 322.5 Nm less than the new motor by 53.4 Nm and average rotational speed is lower by
38rpm.
50
40
30
400
300
The pre-exiting motor
200
20
The pre-exiting motor
10
100
0
0
10
20
30
40
50
0
60
0
t(ms)
10
20
30
40
50
60
t(ms)
(a) The angular displacement of the two motors
(b) The output torque of the two motors
Figure 2 The dynamic behaviours of two motors
2.
Conclusion
In this article, the motor operating mechanism of 40.5kV vacuum circuit breaker is taken as research object.
According to the mechanical load characteristics of the circuit breaker, a new type of permanent magnet
brushless DC motor operating mechanism is designed on the basis of the power higher density and better
mechanical characteristics. The mathematical model of the motor is established with finite element theory.
Compared with the pre-existing motor operating mechanism, the volume of new drive motor is reduced by 23%.
In 200V control voltage, the average output torque and rotational speed can be increased by 53.4 Nm and 38 rpm
respectively.
Keywords:
Vacuum circuit breaker; motor operating mechanism; permanent magnet brushless DC motor;
winding wire diameter and turns; finite element theory
Author’s brief introduction and contact information:
Yao Zheng (1991-), male, master graduate student, research direction for high-voltage switch and its intelligent
operation technology. E-mail:[email protected].
Jianyuan Xu (1962-), male, professor, doctoral supervisor, research direction for high-voltage electrical
appliances, intelligent electrical appliances, distribution system automation, etc.
Kejian Shi (1986-), male, Ph.D, research direction for high voltage electrical appliances and over-voltage in
power systems.
He Bai (1989-), male, master graduate student, research direction for high-voltage switch and its intelligent
operation technology.
CICED2016
Session 7
Paper No. FP1118
Page2/2