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A new rotor position sensorless method for switched reluctance motor drive system (SRD) is described in this paper. Rotor position can be considered as a function of phase current and the variation rate of it. Using the phase current obtained by sensors and the current variation the rotor position can be estimated accurately and quickly. A control strategy of SRD without position sensor is researched...
There are big ripples on current and electromagnet torque under traditional hysteresis direct torque control (HDTC) on motor drive system. To solve these problems, a two dimension cloud model controller is designed to instead traditional hysteretic comparator in this paper, and zero voltage vectors are used to further reduce ripples. The torque error, the flux error and stator flux position are used...
This paper proposes a new space vector PWM technique for four-switch three-phase inverters (FSTPI) under DC-link voltage ripple condition with the optimization of the amplitude of first harmonic output voltage. The proposed algorithm is based on the establishment of quasi-space-vectors with their maximum length and modulation technique, which is simulated the technique for six-switch three-phase inverters...
This work presents the design of a microgripper integrated with force sensor using electrostatic actuation. The single capacitance sensor used in the design can also operate as an actuator when force sensing is not required. The design is optimized in the standard MEMS technology SOIMUMPs. An input voltage of 85 V produces a force of 384 ??N and a displacement of 15 ??m. In dual actuation mode, the...
A standard design process for a novel switched reluctance planar motor (SRPM) is developed in this paper. The paper contains the illustration of the proposed design process for a 500times500 mm prototype. An analysis process is developed with a magnetic model and results from it are verified with finite element analysis (FEA) prior to construction of the prototype. Extensive simulation experimental...
Switched reluctance motors (SRM) have gained more popularity in recent years because of their simple structure, low cost, high reliability, and high torque-to-mass ratio. However, the applications of the SRM have been limited because of their large torque ripple, which causes noise and vibration problems. In order to solve these problems, Ca novel direct torque control (DTC) methodology is directly...
In a three-phase PWM voltage-source inverter, there have voltage losses that cannot be neglected between the reference voltage and the actual output voltage due to the dead time effect. The distortion of voltage leads to serious problems such as current waveform distortion and torque oscillation of motor driving systems. In this paper, an improved method which effective reduces the losses of voltage...
To solve the problems with the conventional direct torque control (DTC) of high speed permanent magnet synchronous motors (PMSM), a variable structure sliding mode direct torque control (VSS-DTC) without sensor is proposed in this paper. The control law of high speed PMSM VSS-DTC and the methodology of speed estimation are presented. The simulation model of the sensorless VSS-DTC system is built and...
This paper presents a high performance direct torque control (DTC) theme for the induction motor (IM). To solve those problems associated with conventional DTC, such as high current, flux and torque ripple, variable switching frequency, the space vector modulation (SVM) is implemented in the DTC to guarantee the constant switching frequency of the inverter. Meanwhile, the design of a robust speed...
This paper presents a novel startup method of a brushless DC motor (BLDCM) without any reverse rotation and vibration. Using short pulse sensing method, the rotor position can be detected dynamically based on the saturation effect of the stator iron. After accelerating the motor to a certain speed at which the back-electromotive force (EMF) method is applied, all the power devices are turned off and...
To reduce the flux and torque ripples, the paper modifies the synthesizing technique, proposes ldquo24 vectorsrdquo method and ldquo24 vectors + altering modulation indexrdquo method, which can be implemented to achieve favorable stator flux linkage and torque control performance in three-level induction motor direct torque control (DTC) system. The improvement of motor performance by proposed schemes...
Four-switch three-phase inverter (FSTPI) is usually adopted as the topology for continuous fault-tolerant operation of a direct torque (DTC) system when inverter fault occurs. Due to that the FSTPI can only provide four voltage space vectors with unequal amplitude, the DTC system performance will deteriorate to a certain extent. To enhance the performance of permanent magnet synchronous motor (PMSM)...
Unreasonable torque ripple in the permanent magnet synchronous motor (PMSM) direct torque control (DTC) drives is caused by the inconsistency between the actual effect on torque of the voltage vector and the exception of the switching table. In order to solve this problem, the number of available non-zero voltage vectors is up to 12 in a sector by dividing stator flux circle into 12 sectors and the...
The basic direct torque control (DTC) scheme may cause undesired torque, flux and current ripples because of the small number of applicable voltage vectors. The discrete space vector modulation (DSVM) method was proposed for DTC to overcome this problem by applying more vectors in one interval. In this paper, after a brief review of the primary concept of DSVM DTC technique, a new scheme of DSVM DTC...
On the basis of analyzing three-level inverter direct torque control principle (DTC) , a new synthesizing vectors PWM method of three-level DTC is presented, which can not only effectively control neutral- point voltage, but also restrain higher dv / dt of output voltage and improve three-level DTC output performance ,reduce torque ripple. Through theory analysis and experiment research, the author...
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