Proceedings of the IEEE

International Conference on Automation and Logistics

Shenyang, China August 2009

Design and Dynamic Simulation of Permanent Magnet

Motor Actuator on High Voltage Circuit Breaker
Lin Xin, Li Yong-xiang, Yang Chuan, Xu Jian-yuan, Liu Ai-min
College of Electrical Engineering, Shenyang University of Technology, Shenyang, China
57626738@163.com

Abstract-A novel permanent magnet motor actuator on high has a limited angle permanent magnet brushless DC servo
voltage circuit breaker is proposed. Based on the characteristics motor with a brake. It directly drives the main shaft of the
requirement of the circuit breaker, a limited angle permanent linkage, which is the rotating shaft. As for the actuator, it both
magnet brushless DC servo motor actuator is designed. By using
the finite element method, the basic characteristics and dynamic
requests the quick response and quick operation of the motor
simulation of starting are carried out, which the simulation results when the circuit has a fault. During the process of opening and
of the motor (such as electromagnetic torque, current, speed and closing requirement, it is necessary to have high preliminary
location parameters) have been analyzed. The analysis is indicated opening speed of the contactor to guarantee the ability of arc
that the rotary motor actuator can provide the mechanism blow-out of the circuit breaker. It should reduce the speed of
characteristics and so it can supply a basis for vacuum circuit contact to weaken the impact to the circuit breaker at the end of
breaker using the rotary motor actuator. opening process. The circuit breaker assembles contact spring
Index Terms-High-voltage Circuit Breaker. Rotary Motor which is compressed at the end of closing process. On the one
Actuator. Motor Design. Dynamic Simulation. hand it can provide the contact force for the contact and
overcome the influence of electric-force in short circuit, on the
I. INTRODUCTION other hand it also can provide a part of the opening energy. But
in the closing process, the actuator must be able to overcome
With the rapid development of power systems, the the counterforce of contact spring [5].
security and requirement of reliability on power system are
also increasingly in recent years. As the mechanical contact is
adopted in the circuit breaker of medium voltage, the
performance of interrupter and actuator become the key to the
high reliability. The traditional actuator mainly has hydraulic
pressure actuator and spring operating mechanism and so on. It
mostly includes many components and complex drive gear,
requesting highly fabrication process, besides the process of
movement can not be controlled. Therefore, it is necessary to Fig. 1 Structure of VCB fixed rotary motor actuator
study one kind of small volume, few components, simple and Through analyzing and computing the opening and
reliable structure [1, 2]. closing process of the 40.5 kV vacuum circuit breaker, the
The motor operating mechanism receive more and more counter-torque characteristics of contact spring and the
attention at present, ABB have already started to develop the equivalent rotary inertia of mechanism are shown in Fig. 2.
motor operating mechanism based on column, tank and The counterforce is mainly composed of the contactor spring,
generator breakers in the circuit breaker actuator, but it still the closing force of contactor and the mechanical friction
need further research to extend and apply the motor operating resistance. The contact spring provides the counter-torque as
mechanism [3,4]. Because the stroke of circuit breaker actuator large as 330 N*m in the overrun stage, which is a propulsion in
is short, large counterforce, and high requirement of speed, the opening but a resist in the closing. The counterforce is
with these characteristics, a limited angle permanent magnet provided by arc extinguish chamber at the process of the
brushless DC motor with finite striking angle is designed. The contact motion, which resists the opening but pushes forward
basic characteristics and dynamic simulation of starting are the closing. The friction resistance is very small which can be
carried out by using the finite element method. The simulation reduced through the measures such as the enhancement of
results of the motor (such as electromagnetic analyzed. The processing precision, lubricate and so on. The relationship
rotary motor actuator can provide mechanism characteristics between the contact stroke and the motor stroking angle is
and so it can supply a basis for vacuum circuit breaker shown in Fig. 3.
adopting the rotary motor actuator.
II. CHARACTERISTICS REQUIREMENT OF VCB
The structure of VCB fixed the rotary motor actuator is
shown in Fig. 1. The motor actuator is a special machine which

Project Supported by Natural Science Foundation of China (50577043)

181
978-1-4244-4795-4/09/$25.00 © 2009 IEEE
 Rotary shift Stator Rotor Brake encoder

N n S

S N

Fig. 4 The structure of permanent magnet brushless DC motor

One pole One pole

α
α

ϕ ϕ
Striking angle Striking angle

Fig. 2 The counter-torque characteristic and the equivalent rotary inertia of

mechanism

a) Multi-slots structure b) Less-slots structure

Fig. 5 The structure of stator
The cogging torques of the two kinds of structures is
analyzed by using the finite element method. The analyzing
results are shown in the Fig. 6. The cogging torque of multi-
slots structure is smaller, the cycle is a pitch, and the cycle is
short and has little influence to the torque. The cogging torque
of less-slots structure is larger, but the cycle is long. As seen
from the Fig. 6, in the structure of less-slots motor the first half
range torque is opposite to the latter half range torque. If the
motor designs reasonably and makes use of the cogging torque,
which may make the motor to accelerate in the first half range
Fig. 3 Relationship of contact stroke and motor striking angle and decelerate in latter half range. The structure of multi-slots
As for the motor actuator, the process of the opening and motor is adopted in this paper, and the structure of few-slots
closing should be able to provide different speed. Breaker motor will be studied in the future article [6, 7].
requests that the preliminary opening speed is up to 2m/s, the
average opening speed is 0.7~2.3m/s, the average closing
speed is 0.6~1.0m/s. The responding time of the motor actuator
from receiving the command to completing the operation is
about within 40 ms in the opening or closing. Therefore, the
actuator requested a larger starting torque to the motor, quick
response, good servo performance, small size and simple
structure.
III. THE DESIGN OF PERMANENT MAGNET DC MOTOR
ACTUATOR
A. Structure
The overall structure of the limited angle permanent
magnet brushless DC motor is shown in Fig. 4. It is composed
of a permanent magnet motor, a brake component, and an
encoder. Through using the encoder the rotor position and Fig. 6 The cogging torque of two kind of stator structure
armature current of motor are detected, which can achieve the As for the high-voltage circuit breaker, each time of the
torque and speed control of motor. opening and closing is only several dozen milliseconds. The
The armature winding of this motor only has one phase, time is extremely short and the movement stroke is limited. As
inletting the DC without commutating, which has simple the motor operating mechanism, the motor only works in the
structure and convenient control. The motor has four-pole and starting and the braking state. Therefore, the motor is designed
the limited angle is 60°. The structure of stator is shown in Fig. in the short time and high overload movement. In order to meet
5, one is multi-slots structure, and the other is less-slots the characteristics requirement of the circuit breaker, the
structure. electric load and magnetic load of the motor are increased
which can reduces the volume of motor. On the one hand this
consideration can meet the miniaturization tendency of high-

182
voltage circuit breaker. On the other hand it also can reduce the ⎧ 2θ ϕ
⎪ l0 (0 ≤ θ < )
cost and weight of motor. Because the higher-speed ϕ 2
⎪
requirement of the opening, it needs a large starting torque of ⎪ ϕ ϕ
motor, and needs to overcome the counterforce of contact ⎪ l0 ( ≤ θ < 180 − )
2 2 (2)
spring and requires a higher torque to the motor in the process ⎪
⎪ 360 − 2θ ϕ ϕ
of the movement. l = ⎨ l0 (180 − ≤ θ < 180 + )
⎪ ϕ 2 2
In order to guarantee the circuit breaker could keep in the
⎪ ϕ ϕ
closing position after receiving the closing operation order, so ⎪ − l0 (180 + ≤ θ < 360 − )
the brake is designed to realize this function. The structure of ⎪ 2 2
the brake is showed in Fig. 7. The brake is mainly composed of ⎪ 720 − 2θ ϕ
⎪ −l0 (360 − ≤ θ < 360)
brake disk, armature iron, winding and spring. When the brake ⎩ ϕ 2
winding is on, the magnetic field produced by the winding
Which: l0: Length of armature windings; l: Equivalent
causes the armature iron to attract the magnetic yoke. The
length of the armature winding in a cycle; R: Winding
armature iron and the brake disk are separated (release) when
resistance; θ: Angle between permanent magnetic and armature;
winding is off, the flux vanished and armature iron is released.
The spring exerts pressure to the armature iron for making the ϕ : The magnetic phase angle of armature windings in each
friction disk of the brake disk compressed, which is to produce pole; M: The electrical and magnetic torque; ev: Moving EMF;
brake torque to achieve the aim of braking [8]. ee: Induced EMF; UC: Capacitance voltage; C: Capacity; i:
Winding current; B: Flux density of the gap; r: Radius of rotor;
Armature iron
Winding
Spring
ω : The speed of rotor; L: Winding inductors; J: Rotating
Brake disk
inertia; M0: Anti-torque; ω: Speed of motor.
The shift of motor IV. ANALYSIS AND DYNAMIC SIMULATION OF ROTARY MOTOR
ACTUATOR
Analyzing and calculating the preliminary designed motor
by using the 2D finite element analysis software [11-14]. The
slot number of each pole and each phase is 3, the parallel few
Fig. 7 The structure of the brake slip of stationary winding is 1, the single-phase current flow in
The high performance of the digital processor DSP servo winding, the winding turns is 120, leakage inductance is
controller of the motor actuator is designed. Through the 0.1mH, winding resistance is 1.125Ω, material of primary
control to the torque, the speed and the position of motor can magnetic cores of the silicon steel is D23, N35SH and 10th
realize the intelligent control of the circuit breaker. The brake steel is used in Secondary. The Nd-Fe-B permanent magnet
is installed at the end of the motor and it is controlled by the N40 and 10th steel are used in the rotor. Setting the initial
motor controller. When the brake turns on and the braking speed and initial current as zero, the moment of inertia of the
function vanishes, the movement of the circuit breaker ends. rotor as 0.07 kg*m2, 200V DC power is adopted during the
When the brake turns off and the brake is braking, the motor closing and opening.
stop rotating and keep in the position [9, 10].
A. The process of opening
B. Mathematical models Through the simulation and computation of the opening
Limited angle permanent magnet brushless DC motor has process, the current and torque curves of the motor actuator in
a unique movement characteristic, that it can impact the opening are obtained which are shown in figure 8. As seen
movement factors of the motor mainly such as the starting from figure 8, the curve 1 is the torque characteristic and curve
position of motor, the distribution range in each pole. The 2 is the current characteristic. The maximum current reaches
characteristic equations of motor which relies on energy 95A and maximum torque 230N*m in opening. In the process
storage capacitor for power are as follows: of opening, the torque has a certain pulsation, but the tendency
⎧ M = Bil is basically according with the current. In the opening, the
⎪e = Blrω contactor spring provides part energy to the opening energy,
⎪ v while cumulates energy to the contactor spring in closing.
⎪ di Therefore, the closing current and closing power are bigger
⎪ee = L (1)
⎪ d t than opening.
⎨U c = iR + ev + ee The stroke angle and rotational speed curves are shown in
⎪ Fig. 9. As seen from Fig. 9, the curve 1 is the revolution
⎪i = −C dU c
⎪ dt characteristic and curve 2 is the striking angle characteristic.
⎪ dω The motor rotational maximum speed achieves 1100r/m before
⎪M + M 0 = J the overrun stage ends, the motor rotational maximum speed
⎩ dt
achieves 620r/min, and the motor maintain the position of
opening or closing because of the brake. The striking angle of

183
motor actuator is 61.7°, and the time of opening operation is
about 21.5ms.

Fig. 11 Torque and current curves of motor actuator during closing

Fig. 8 Torque and current curves of motor actuator during opening The stroke angle and rotational speed curves are shown in
Fig. 12. As seen from Fig. 12, the curve 1 is the revolution
characteristic and curve 2 is the striking angle characteristic.
The revolution rapidly reaches to the maximum value
(620r/min) and then reduces. The speed of motor sharply
reduces to zero and stays in the position of closing because of
the role of the maintenance device. The striking angle of motor
actuator is 61.7°, and the time of opening operation is about
30.5ms.

Fig. 9 Revolution and stroke angle curves of motor actuator during opening
The stroke and speed curves of contact during the opening
are shown in the Fig. 10. As shown in the Fig. 10, the curve 1
is the speed characteristic and curve 2 is the stroke
characteristic. The opening time of contact is 9.1ms, the
preliminary speed of opening is up to 2.7m/s, and the average
opening speed is up to 2.78m/s.
Fig. 12 Revolution and stroke angle curves of motor actuator during closing
The stroke and speed curves of contact during the opening
are shown in the Fig. 13. As shown in the Fig. 13, the curve 1
is the speed characteristic and curve 2 is the stroke
characteristic. The closing time of contact is 19.2ms, the
preliminary speed of closing is up to 3m/s, average closing
speed is up to 1.3m/s. The character of speed basic meets the
requirement of the interrupter. It provides a possibility that the
process control of the contact can be achieved.

Fig. 10 Speed and stroke curves of contact during opening

B. The process of closing

Through the simulation and computation of the opening
process, the current and torque curves of the motor actuator in
opening are obtained which are shown in Fig. 11. As seen from
Fig. 11, the curve 1 is the torque characteristic and curve 2 is
the current characteristic. The maximum current reaches 125A
and maximum torque is 300N*m in closing. On the process of
closing, the torque has a certain pulsation, but the tendency is
basically according with the current.
Fig. 13 Speed and stroke curves of contact during closing

184
 V. CONCLUSION [2] Chen Zhen-sheng. The principle and Application of the Circuit-breaker with
Presently New Driving Mechanism [J].Jiangsu apparatus, 2004(6):16-38.
Based on the characteristics requirement of the 40.5kV [3] Bosma A, Thureson P-O．A new reliable operating mechanism for HVAC
VCB, the motor actuator is designed. The simulation model of circuit breakers[C].Transmission and Distribution Conference and
Exposition，2001：573-577．
the rotary motor actuator is established by using the finite
[4] Bosma A, Cameroni R. Introducing a new generation of operating
element method. The basic characteristics and the starting mechanism for high voltage AC circuit breaker[J]．Journal of Electronic
characteristics of the motor are simulated in the rotary motor Engineering，2002,21(3)：233-240
actuator system. The simulation results can accurately reflect [5] Lin Xin. Permanent magnetism operating mechanism & vacuum circuit
the magnetic field distribution and the characteristics of the breaker [M].Beijing: Mechanism Industry Press, 2002.
starting process of the limited angle permanent magnet [6] Tang Ren-yuan. Modern Permanent Machines Theory and Design [M].
Beijing: China Machine Press, 2005.
brushless DC motor. [7] Li Zhong-min,Liu Wei-guo. Rare Earth Permanent Magnet Electrical
As for the limited angle permanent magnet brushless DC Machines [M]. Beijing: National Defense Industry press, 2000.
motor, the torque is up to 330 N*m, the speed reaches to the [8] Lin Xin, Ma Yue-qian, Xu Jian-yuan, Wang De-shun. Design and Analysis
requirements of 600 r/min, the rotation angle reaches to 60°, of Driving Motors of Novel Motor Operating Mechanism [J]. Journal of
Shenyang University of Technology,2008,30(2):129-13．
the running time is less than 40ms. In the opening operation, [9] Lin Xin, Wang De-shun, Xu Jian-yuan. Linear Servo Motor Operating
the average speed of contact is 2.78m/s and the operation time Mechanism and Control Technique for High-voltage Circuit Breaker [J].
is about 9.1ms. In the closing operation, the average speed of Proceedings of the CSEE，2008,28(27):137-141.
contact is 1.3m/s and the operation time is about 19.2ms. [10] Lin Xin, Wang Xiao-yu, Xu Jian-yuan, Wang De-shun. Research of Self-
The analysis results have indicated that the permanent adapting Single Neuron PID Control in Permanent Magnetic Linear Servo
Motor Operating Mechanism of High Voltage Circuit Breaker
magnet motor actuator is able to satisfy the characteristics [J].ELECTRICAL ENGINEERING, 2008. (9):68-73.
requirement of the circuit breaker and it can provide a theory [11] Wang Xing-hua，Li Qing-fu，Wang Shu-hong．Analytical Calculation
basis for circuit breaker using the motor operating mechanism. of Loaded Magnetic Field and Electrical Magnetic Torque in Brushless
Through using the servo control in permanent magnet motor DC Motor [J]. Proceedings of the CSEE，2003, (4)：140-144．
actuator, it can overcome the uncontrollability of traditional [12] Sebastian T. Analysis of induced EMF waveforms and torque ripple in a
brushless permanent magnet machine [J] ．IEEE Trans on Magnetics，
actuator and it has an important significance that it can enhance
1999，32 (1)：195-200．
the intelligent of switchgear. [13] Hu Min-qiang，Huang Xue-liang．Numerical Computation Method of
REFERENCES Eclectic Machine Performance and its Application [M] ． Nanjing ：
Southeast University Press,2003．
[1] Lin Xin, Wang De-shun, Ma Yue-qian. A New Generation Linear Servo [14] Wang Xing-hua, Li Qing-fu, Wang Shu-hong．Analytical Calculation of
Motor Operating Mechanism for High-voltage Circuit Breaker [J].Electric
Loaded Magnetic Field and Electrical Magnetic Torque in Brushless DC
age, 2007(2):68-70
Motor[J].Proceedings of the Chinese Society for Electrical
Engineering,2003,(4):140-144．

185