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1、No-Coupling SACS Motor Testing Li Yunfeng Xu Dianguo Shi Jingzhuo Zhang qiuye Dept. of Electrical Engineering, Harbin Institute of Technology, Harbin, 150001, PR China Abstract: The paper analyzes the disadvantages of the conventional testing system for the single-phase AC series-excited motor (SACS
2、M), introduces a kind of no-coupling motor testing system: the motor testing without the sensor speed detection; constructs the mathematic model and gives the method of parameter identification; describes the method of speed detection; puts forward a kind of new genetic algorithm based on the social
3、 hierarchic rank which is used to parameter identification of motor model in SACSM testing system, and adopts the idea that reduces searching scope of genes according to individual fitness, and designs a changeable scope searching operator which makes the genetic algorithm optimize parameters of mot
4、or more effectively. Experiments show that the testing system can be maintained conveniently to help obtain the desired results. Keywords: Single-Phase AC Series-Excited Motor, Speed Detection, Parameter Identification, Genetic Algorithm. .INTRODUCTION In general, the SACS motor is tested using the
5、traditional torque testing systems. In these systems, the known and changeable load is coupled with the motor to obtain the performance of the motor. This direct testing method has some disadvantages1: 1) The testing system is complex with high cost; 2) The torque and the rotating speed should be se
6、t according to the motor and the testing plan. Great effort and long time is needed; 3) The testing system is not easy to be installed and debugged, and the precision of the testing result depends on the level of the manipulator; 4) Easy to fail in functioning. Fig.1 shows a kind of simplified fixtu
7、re drawing. The method is founded upon a basic physical principle: the torque applied to a rotating mass of known inertia can be calculated by measuring the change in speed over a fixed period. That is, TimespeedinChangeloadInertialTorque= (1) In the testing system employing this method, the motor u
8、nder test is mechanically connected to the test system via a test fixture consisting primarily of a rotating shaft supported upon high-quality bearings and a flywheel of known inertial and a high-resolution rotary digital encoder mounted on that shaft. A computer is needed to employ algorithms. And
9、another hardware is needed to link the encoder with the computer. This method can be used to test any type of motors without change. And because of the simple arithmetic, the testing time is very short. However, it can only obtain the torque-speed characteristic, but it is not enough, and so a lot o
10、f hardware is needed that the cost and the complexity are observably increased. The most important disadvantage is the need of the coupling between the motor and the testing equipment. To ensure the precision, the coupling should be very proper to decrease the eccentric friction and the vibration. T
11、he need of the coupling also increases the time of the whole testing process. The following will introduce a kind of new testing method: the no-coupling motor testing. . low friction bearing digital encoding flywheel(inertia load) motor under testmotor shaft couplingFig.1 Simplified “digital torque
12、measurement”fixture1 Fig.2 Actual current and voltage waveform of starting process Fig.3Winding current waveform and the real-time FFT result 0-7803-7768-0/$17.00(c) 2004 IEEE0-7803-7768-0/$17.00(c) 2004 IEEE0-7803-7768-0/$17.00(c) 2004 IEEE0-7803-7768-0/$17.00(c) 2004 IEEE0-7803-8269-2/04/$17.00 (C
13、) 2004 IEEE0-7803-8269-2/04/$17.00 (C) 2004 IEEE15901590Authorized licensed use limited to: Technische Universitaet Berlin. Downloaded on July 28,2010 at 11:28:19 UTC from IEEE Xplore. Restrictions apply. Fig.2 is the actual waveform of the current and the voltage acquired from a test of a motor sam
14、ple(U-4615). The rated voltage is AC 110V and the whole testing time is 2 seconds. The armature current rises quickly to the maximum value, after that, it declined slowly to the stable value. Fig.3 is a tested waveform of the armature current on a motor and the frequency spectrum that is obtained by
15、 the real-time FFT. In the figure, the distortion caused by the phase commutation is obvious, and the high frequency components concerned with the rotational speed of the motor appeared. From the FFT spectrum in Fig.3, we can observe the relatively obvious harmonic components (the parts have been dr
16、awn by circles) concerned with the rotational speed of the motor. The no-coupling motor testing that can obtain the characteristics of the motor is a kind of testing method in which the motor is only needed to be fixed and be powered to run for a short time, while the rotating speed has raised from zero to the no-load steady speed, the motor voltage and winding current data is
