This paper presents a novel control method to improve the efficiency of low-voltage DC-DC converters at light loads. Pulse Width Modulation (PWM) converters have poor efficiencies at light loads, while pulse frequency modulation (PFM) control is more efficient for the same cases. Switching losses constitute a major portion of the total power loss at light loads. To decrease the switching losses...

due to the high efficiency and low switching losses of resonant power convertors in comparison with switching convertors, nowadays there is a growing trend towards these convertors. however, because of the high frequency of switching in such convertors, it is quite difficult to present an efficient control method. in this paper, based on the state feedback method and using pole placement techni...

Axial field flux switching motor with sandwiched permanent magnet (AFFSSPM) is a novel of flux switching motor. Based on the vector control method, the mathematical model of the AFFSSPM is derived and the operating performance of the AFFSSPM in the overall operating region is investigated.A novel control method for the AFFSSPM drive system, including the id =0, maximum torque per ampere, consta...

When the process is highly uncertain, even linear minimum phase systems must sacrifice desirable feedback control benefits to avoid an excessive ‘cost of feedback’, while preserving the robust stability. In this paper, the problem of supervisory based switching Quantitative Feedback Theory (QFT) control is proposed for the control of highly uncertain plants. According to this strategy, the unce...

This study attempted to investigate the impact of teacher’s code-switching on the acquisition of a problematic grammatical structure, namely, object relative clauses, by intermediate EFL learners. Moreover, a secondary objective of the study was to determine the EFL learners’ attitudes and opinions regarding the effectiveness of teacher’s code-switching in their learning of a specific aspect of...

Hysteresis current control method is vastly used in PWM inverters because of simplicity in performance, fast control response and good ability in limiting peak current. However, switching frequency in hysteresis current control method with fixed bandwidth has large variation during a cycle and therefore causes non-optimal current ripple generation in output current. One of basic problems in imp...

unlike traditional power grids, smart grids have the advantage of bidirectional power flow and having distributed generations. distributed generation systems are usually supplied by renewable sources which can cause unpredicted voltage fluctuations as a result of being intermittent. while traditional compensating devices deal with the problem of voltage fluctuation and reduced power quality wit...

this paper gives a detailed analysis of direct torque control (dtc) strategy in a five-level drive and proposes a 24-sector switching table. the overvoltage problem due to high dv/dt is reduced compared to the 12-sector dtc. using all vectors leads to better flexibility and reduces speed oscillations. simulation and experimental results for a 3kva prototype confirm the proposed solutions. a tms...