Analysis Of 12- Level Cycloconverter To Minimize Thd (Total Harmonic Distortion) Level In 3-Phase Induction Motor

These harmonics are higher than essential frequencies and cause Total Harmonics Distortion (THD) which increases the rms current and generates more warmth in the load. Numerous techniques are used to suppress the harmonics to limit the warmth in the load. Another procedure is utilized in this work to limit THD and the method to beat the low exhibition of a traditional PWM (pulse width tweak) control. In this work, the desired output voltage is accomplished by contrasting the desired sinusoidal waveform (adjusting signal) with a high frequency three-sided waveform (transporter signal). Industrial applications demands high force and long life expectancy motor drives. Three phase motor drives have restricted force density consequently Multiphase motor drives are better solutions for high force density and substantial loads. In this work a 12 level cycloconverter is designed to drive three Phase load. The loads used in the industries almost nonlinear loads like motors. Thusly, because of these nonlinear loads extra harmonics incited at the output of the 12 level cycloconverter drive with major frequency. The harmonics and THD got using our proposed technique is thought about using Mat lab/Simulink

Model Predictive Current Control of Multiphase Motor at Low Carrier Ratio

Multiphase motors have multiple control planes, and harmonics are decoupled in different planes. Multiphase motors can improve magnetic field distribution, power density and core utilization by injecting certain harmonic currents into the harmonic planes. In the harmonic plane control process, due to the switching frequency of the inverter being limited, the ratio of the switching frequency to the current frequency (the carrier ratio) of the harmonic plane is low, the digital control delay increases, and the inverter output current contains more harmonics, which makes it difficult for the proportional-integral (PI) current controller to effectively control the d-axis and q-axis currents of the harmonic plane and thus unable to track the given values stably. Moreover, the PI current controller is relatively dependent on the motor parameters. For these reasons, a model predictive current control method with predictive error compensation is proposed. Taking a nine-phase induction motor as an example, the control voltage is calculated by the cost function and corrected by the current predictive error, which realizes the current control method at a low carrier ratio. Additionally, the robustness of the control method is analyzed after the parameters of the multiphase motor have large errors. The experimental results show that the proposed method can control the current of the harmonic plane at low carrier ratio, accurately track the harmonic current commands and attain strong robustness for the motor parameters.

Multiphase Induction Motor Drives for Gear-Less Electric Vehicle Applications

Qatar has some major research priorities, targeting; reducing carbon footprints, developing smart cities and smart grids; and these demand high deployment of electric cars in near future. Qatar is an highly progressive country adopting to new evolving technologies at a fast pace. The proposed project is aimed at the development of a robust, highly reliable, efficient and wide speed range multiphase motor drive system that falls within the right context of the current research priorities of the Qatar University and the State of Qatar. The idea here is to use pole phase modulation technique to enhance the speed-torque control region of a multiphase motor drive system so that gear-less opeartion can be achieved in EV. Advantages and Disadvantages of the proposed pole phase modulated IM drives:  In high pole operation, the PPMIM drive is able to supply the high initial torque for fast acceleration and hill climbing.  The rated torque of the PPMIM drive in the high pole is k times greater than the low pole mode. For example, in 3-phase 12-pole mode, the 9-phase PPMIM drive is able to supply 3 times of the rated torque as comparted to 9-phase 4-pole mode.  In low pole mode, the PPMIM drive is able to supply high speed which is k times greater than the high pole mode.  The PPMIM drives are capable to generate 3 or 4 speed and torque variations. So, the mechanical gearbox system in conventional IC Engine based vehicles can be eliminated with the PPMIM drives, which will reduce the size and weight of the vehicle. Even though the PPMIM drives have several advantages (as mentioned above), on the other side they have a few disadvantages also such as:  To achieve the high starting torque in high power applications, the PPMIM drives has to operate in high pole and low phase mode, which magnifies the magnitude of space harmonics in the air gap.  The magnetizing inductance of the machine is inversely proportional to the square of the number of poles, which lowers the power factor.

Multiphase SVPWM Strategy Analysis and Implementation of Seven-Phase Permanent Magnet Synchronous Motor

The multiphase motor drive systems have become a focus in many application areas such as ship electric propulsion, urban mass transit, aerospace, and weapon equipment, as they are characterized by high power density, low torque pulsation as small torque ripple, large output power, strong fault tolerance, and high reliability. However, with the increase of the phase number of the motor, the current harmonic component increases correspondingly, which leads to the decrease of the control performance compared with the three-phase system. In order to overcome this challenge, implementation method of driving control technology for seven-phase permanent magnet synchronous motor (PMSM) based on SVPWM algorithm is discussed thoroughly in this paper. Simulink and experiments have been developed to check its practical feasibility. The results show that the near-six vector SVPWM algorithm (NSV-SVPWM) achieves better performance than other methods.

Multiphase PMSM with Asymmetric Windings for Electric Drive

Multiphase permanent magnet synchronous motors (PMSM) are widely utilized in high power and high reliability electric propulsion systems. In electric propulsion systems, the motor may work at a low efficiency area for a long time, which increases energy consumption and reduces cruise range. In order to improve motor efficiency, this paper proposes a multiphase motor structure. The stator winding of proposed motor consists of three independent windings that have different rated speed and torque. In this paper, winding match mode, operation characteristic and efficiency characteristic are analyzed, and a torque distribution strategy with optimal efficiency is given. The results show that in propeller load such as electric aircrafts and ships, the proposed motor can reduce motor total loss and temperature rise in a drive cycle, which improves system efficiency, reliability and fault tolerance performance.

Predictive-Fixed Switching Current Control Strategy Applied to Six-Phase Induction Machine

In applications such as multiphase motor drives, classical predictive control strategies are characterized by a variable switching frequency which adds high harmonic content and ripple in the stator currents. This paper proposes a model predictive current control adding a modulation stage based on a switching pattern with the aim of generating a fixed switching frequency. Hence, the proposed controller takes into account the prediction of the two adjacent active vectors and null vector in the ( α - β ) frame defined by space vector modulation in order to reduce the (x-y) currents according to a defined cost function at each sampling period. Both simulation and experimental tests for a six-phase induction motor drive are provided and compared to the classical predictive control to validate the feasibility of the proposed control strategy.