In this paper, the robust speed control of an induction motor is investigated, and a parameter-dependent model is addressed. The proposed scheme includes the feedback of states and the integral of the tracking error. In practice, considering the specification of the drive circuit, the saturation phenomenon of control signals is addressed. It is noted that the saturated signal is represented as a perturbed signal, which can be further investigated to determine the achieved robustness. Regional stability and H ∞ performance are discussed in this paper, where the derivations of feedback gains are formulated in terms of linear matrix inequalities (LMIs). To evaluate the control performances, a DSP-based scheme for an induction motor was set up. Experimental results, associated with versatile command profiles and load conditions, show that the proposed system achieves satisfactory performance from the viewpoint of tracking accuracy and disturbance rejection.
The output flow pulsation characteristics of the hydraulic pump due to the structural characteristics may cause pump source fluid pressure pulsation and even cause the equipment to vibrate, which will affect the life and working reliability of the equipment. Scholars have done a lot of theoretical and simulation analysis on the characteristics of fluid flow and pressure pulsation caused by the specific structure and structure of the plunger pump, but there are few comparisons and analyses of the simplified model of the plunger pump and the pressure pulsation characteristics with experiments. In this paper, AMESim software is utilized to establish a simplified model of one seven-plunger hydraulic pump, and simulate and analyze the pump source fluid pressure pulsation characteristics of different system load pressures at a constant speed. An experimental platform for testing pump fluid pressure pulsation was designed and built, and the actual measurement and simulation results of pump fluid pressure pulsation were compared and analyzed. The results show that the system simulation data is in good agreement with the measured data, which verifies the correctness of the simplified model of the plunger pump. At the same time, it is found that the fluid pressure pulsation of the pump source exhibits broadband and multi-harmonic characteristics. At a constant speed, as the load pressure of the hydraulic system increases, the pump source fluid pressure pulsation amplitude increases, the pressure pulsation rate decreases, and the impact on the fundamental frequency amplitude is the most significant. The research results can provide a theoretical basis for suppressing the pressure pulsation of the pump source fluid and reducing the vibration response of a hydraulic pipeline under the action of the pulsating harmonic excitation.
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