Due to its unique and attractive characteristics, the induction motor (IM) has been widely used for years. How to design an IM with desired characteristics and how to realise high performance control for a given IM, these have always been hot research topics to many researchers. No matter what control technology is used to achieve high‐performance drive of IM, it depends on in‐depth understanding of motor parametric characteristics and their accurate acquisition. An effective determination method is proposed to improve the parameter accuracies of the equivalent circuit for induction motors by combining non‐rotor test with dual‐load test and using this method to measure and analyse the parametric characteristics of IM. Experimental validations are carried out on two induction motors with open‐slot rotor and closed‐slot rotor, respectively. Compared with the traditional methods, the proposed method has higher accuracy and can be an effective tool for design, control, and testing research of IM.

The equivalent circuit model is an effective tool in the research of 3-phase induction motor. It can convert the complex electromagnetic phenomena into circuit ones and enable the study of motor control and operation to be processed with circuit theory and circuit analysis tools. Obviously, to achieve precise control of the induction motor, it is necessary to use the precise circuit parameters, and master how parameters change with voltage, current and frequency of the motor. Based on the equivalent circuit model with parallel excitation branch considering iron loss, the measurement methods to obtain the precise parameters are introduced and analyzed in the paper. The results show clearly the reasonable ways to get the precise motor parameters, which is significant to the R&D on high performance induction motor control and application.

In its applications, the starting performance of a 3‐phase induction motor (IM) is very important. The starting torque of the motor should be as high as possible within the safe current range of the motor driver. In the study, the optimal frequency for motor starting is derived from the frequency characteristic of the IM. Through the analysis of the characteristics, the optimal frequency point can be found, which is able to generate the maximum torque per unit drive current. Both theoretical analysis and experiments show that the IM with the optimal starting frequency can generate the maximum torque for a given current. The traditional methods, such as soft‐start, can reduce the starting current, but at the expense of lowering starting torque. This starting technology can solve the problem caused by traditional methods, improve the starting performance of the motor system significantly, and lower the requirement for the current redundancy of the motor driver effectively.

In this paper, we demonstrated a method of filling the air holes of a photonic crystal fiber (PCF), coated with gold film, with magnetic fluid (MF) to enhance the Surface Plasmon Resonance (SPR). The simulation results show that at the wavelength of 1260–1675 nm, the minimum loss coefficient of the y-polarization mode is 4.7 times that before filling with MF, and the x-polarization mode is 0.45 times greater. Then, based on this method, we designed a polarizing filter with a core diameter of 9 µm. The numerical simulation results indicate that it not only maintains the same core diameter as the single-mode fiber, but also has a larger bandwidth and a higher extinction ratio (ER). Additionally, we can optimize its ER at a specific wavelength by adjusting the magnetic field.

The starting performance of induction motor (IM) has a prominent influence on the redundancy design and cost control of motor drivers. To make the starting torque as high as possible under the special setting of starting current, a new approach for improving the starting performance of three-phase IM is proposed in this paper. First, the frequency characteristic of the starting torque, which is different from the optimal starting torque per ampere (OSTPA) proposed by the author previously, is investigated based on the universal T-type equivalent model that considers the iron loss. The analysis results confirm the existence of an optimal starting frequency (OSF), which makes the starting torque much higher than that at rated frequency. Secondly, complete discussions of starting initial values are reported and discussed, including starting voltage and motor parameters. Then, the step-by-step starting algorithms based on OSF are provided. Finally, the OSF and its starting strategy are tested on a rapid control prototype system, and the comparison between computed and measured results confirms the feasibility and effectiveness of the proposed approach.

This paper presents the brushless electrical excited synchronous machine drive system. A rotary transformer transfers the power to the rotor field winding of synchronous machine. A 12 slot - 10 pole brushless excited synchronous machine (BESM) is designed and analyzed. The super-twisting sliding mode direct torque and flux controller (STSM-DTC) is investigated for this motor drives. The tests show that STSM-DTC displays a very robust behavior.