To avoid inconvenience caused by shaft rotation and improve immunity to measurement noises, an elaborately designed scheme is proposed for parameter identification of induction motors. After analyzing the responses of a simple step-voltage test, a sequence of pseudorandom signals, customized to excite abundant dynamics in the featured frequency band of the motor, are injected into the stator in a single-phase mode at standstill. The crucial feature of the proposed scheme is that a nonlinear procedure is introduced to minimize "predicted errors" of the estimation model, which lowers influences of measurement noises notably, and thus the design of low-pass filters is simplified greatly. Experimental comparisons are carried out, including not only tests on a squirrel-cage motor, but also extended tests on a wound-rotor motor to testify accuracy of rotor-side parameters, both using a real inverter. The results indicate that the proposed scheme is able to estimate parameters required by controllers accurately in the noisy environment, and improve performances of sensorless motor drivers.Index Terms-Excitation signal design, prediction error method (PEM), self-commissioning, sensorless control, single-phase test.

In this study, photosensitive resin mould was made by stereolithography technology to inject individualized polyether ether ketone (PEEK) parts. In simulation experiment, the temperature field of the PEEK injection mould was analysed by finite element analysis; it was preliminarily determined that the resin mould will not be deformed during the injection process. The optimum parameters of PEEK injection process were obtained by orthogonal experiment: injection temperature 373 °C, injection pressure 11 MPa and injection speed 70%. Mechanical tests were carried out on PEEK samples injected by this process. The results showed that the average tensile strength was 96.4 ± 2.28 MPa, the average bending strength was 147.654 ± 9.36 MPa, and the impact strength was higher than 10 kJ/m 2 . The experimental results show that it is feasible to produce photosensitive resin mould to inject individualized PEEK parts by stereolithography. Photosensitive resin mould has lower cost, shorter production cycle and no waste of PEEK material during injection process. The injection method in this study greatly reduced the production cost of individualized PEEK parts and can obtain PEEK parts with good mechanical properties in a relatively fast time.

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