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Nonideal switching characteristics of voltage source inverter (VSI) will result in distortions in both phase currents and reference voltages of a permanent magnet synchronous machine (PMSM) drive system, which will also consequently introduce ripples into the output speed and shaft torque, and result in a performance deterioration in the state observation control. To solve this issue, a method of directly extracting and compensating the nonlinear voltage disturbance due to VSI nonlinearity employed in PMSM drives is proposed in this paper. Firstly, the distorted voltage due to VSI nonlinearity is directly extracted via a harmonic separation scheme, which can be easily compensated by a proportional integral controller afterwards. Since both 6th harmonic and DC terms of dq-axis distorted voltages due to VSI nonlinearity are well compensated, the proposed method shows sufficiently good performance under both $i_{d}=0$ and maximum torque per ampere controls ( $i_{d} < 0$ ), as verified on two prototype PMSMs being salient pole and non-salient pole, respectively, both developed for a low-speed rotary actuator. In addition, the application of proposed method to state observation controls such as the model-based sensorless control and the deadbeat predictive current control, is finally investigated. Test results manifest that the proposed method can effectively improve the accuracy of observed rotor position/speed, and the ability of current tracking.

In motor drives, distortions of phase voltages and currents are often caused by nonlinear effects of inverters such as dead time, turn-on delay, turn-off delay and voltage drop of power devices. To eliminate these distortions, the dead-time compensation voltage is usually investigated. Furthermore, the relationship between the dead-time compensation voltage and phase currents is nonlinear, which is related to not only the parameters mentioned above, but also the snubber and parasitic capacitance of inverters. A nonlinear function is constructed to model the nonlinear relationship in this paper. To identify the nonlinear function, a method based on artificial neural networks is proposed without inverter parameters. According to the criterion that the trajectory of voltage vector in $\alpha - \beta $ coordinate system is a circle, an adaptive law is constructed to modify the parameters of the nonlinear function. Therefore, the nonlinear dead-time compensation voltage model is obtained accurately, where the distortions of voltages and currents are reduced without any additional hardware. Applying this method to the current predictive control, the bandwidth of a current loop is increased by 500Hz. Effectiveness of the method is verified by experiments.

Residual placenta is one of the common types of postpartum complications in clinical practice. Residual placenta is also the main and most common cause of late postpartum hemorrhage. This article proposes a spatial pyramid loop module, which solves the problem that the existing network structure cannot effectively extract the semantic information and category information in the image at the same time. The spatial pyramid structure is used to effectively extract the semantic information and category information. In addition, this article proposes to use cyclic convolutional network to realize the transfer function of information at different scales, and build it in the spatial pyramid structure to further strengthen the ability to extract semantic information and category information. This article proposes a feature fusion module to solve the impact of image classification network used in the base network in the existing network structure. The attention mechanism is used to achieve the effective fusion of high-dimensional features and low-dimensional features in the base network to reduce the influence of the base network, so as to better recover the recognition and prediction results. A semantic category loss function is proposed to supervise the categories of objects in images. This article builds it on the feature layer with the smallest scale, which not only increases the intermediate supervision to make the network fully converge, but also reduces the difficulty of extracting category information, and makes full use of the information transfer function of the cyclic convolutional network. This article introduces uncertainty information into the field of image segmentation to provide the accuracy of segmentation. For the purpose of uncertainty information, this article improves the network structure. At the same time for the image segmentation task, this article improves the Bayesian cross entropy loss function. The experiment verifies the necessity of improving the Bayesian crossover function in this article and the effectiveness of the conditional random field used in this article, and also verifies the effectiveness of the proposed semi-supervised learning method.