Low Switching Frequency SPWM Strategies for Open-winding Machine with Low Current Harmonics

Author(s):  
Lei Xu ◽  
Z Q Zhu ◽  
Luocheng Yan
2019 ◽  
Vol 8 (4) ◽  
pp. 3933-3935

An adjustable speed drive creates the harmonics. The novel current injection circuit does not need any additional active devices. With the significant reduction in current harmonics, the AC input line current is sinusoidal. The ZVS technique is used for all the switches operation. The rectifier diodes are by soft switching. The output voltage regulated by fixed duty ratio with varying switching frequency. The advantages of proposed AC-DC-AC systems are low price, compact, high efficiency, and simplicity. Nine level diode clamped inverter produces the voltage harmonics of 8.75%. The Total Harmonic Distortion (THD) of input current is as low as 7.72 % and power factor as high as 0.99. Theoretical results are verified initially through PSIM simulation and validated with an experimental prototype of 2.5Kw.


Author(s):  
V. Mohan ◽  
N. Stalin ◽  
S. Jeevananthan

The pulse width modulated voltage source inverters (PWM-VSI) dominate in the modern industrial environment. The conventional PWM methods are designed to have higher fundamental voltage, easy filtering and reduced total harmonic distortion (THD). There are number of clustered harmonics around the multiples of switching frequency in the output of conventional sinusoidal pulse width modulation (SPWM) and space vector pulse width modulation (SVPWM) inverters. This is due to their fixed switching frequency while the variable switching frequency makes the filtering very complex. Random carrier PWM (RCPWM) methods are the host of PWM methods, which use randomized carrier frequency and result in a harmonic profile with well distributed harmonic power (no harmonic possesses significant magnitude and hence no filtering is required). This paper proposes a chaos-based PWM (CPWM) strategy, which utilizes a chaotically changing switching frequency to spread the harmonics continuously to a wideband and to reduce the peak harmonics to a great extent. This can be an effective way to suppress the current harmonics and torque ripple in induction motor drives. The proposed CPWM scheme is simulated using MATLAB / SIMULINK software and implemented in three phase voltage source inverter (VSI) using field programmable gate array (FPGA).


2004 ◽  
Vol 13 (05) ◽  
pp. 1065-1078 ◽  
Author(s):  
MOHAMMAD HAERI ◽  
KAMIAR KORDARI

The power quality has become a major concern since late 1980's. There has been increasing interest in studying power quality problems, one of which is the existence of the current/voltage harmonics. In order to eliminate these harmonics, different methods have so far been proposed and developed. In this paper, line current harmonics reduction is achieved by using an active filter. More specifically, our aim is to introduce a proper control design method for the current control part of the active filter. To achieve the goal, two different predictive controllers are examined. Due to the existing physical constraints (switching frequency and computational limits) in real applications, a new predictive control approach is proposed. The performance of this controller is compared to those obtained by two existing predictive controllers as well as commonly used PI controller through computer simulations considering various circumstances.


Author(s):  
Yong Li ◽  
Hao Wu ◽  
Qiaorui Si ◽  
Yonggang Liu

The vibration noise of the distributed drive autonomous ground vehicle (AGV) is mainly produced by the inverter-fed brushless DC permanent magnet in-wheel motor (PMIWM). It is necessary to reduce the vibration noise level of the PMIWM driven by pulse width modulation (PWM). A suppression approach of electromagnetic vibration noise for PMIWM is investigated. Firstly, the air gap magnetic field of the inverter-fed PMIWM was analyzed. The electric current harmonics and the unbalanced magnetic force (UMF) were investigated. The natural frequency and noise of the PMIWM were presented. Then, flux-weaken approach was employed to maintain the robustness of the PMIWM when a sudden drop of DC bus voltage. The random switching frequency (RSF) PWM control method based on two state Markov chain is proposed to decrease the amplitude of the harmonics caused by the switching frequency and the multiple switching frequencies. The experimental results show that the RSFPWM can not only effectively reduce the vibration noise and the inverter losses, but also improve the robustness of the PMIWM control system under unpredictable uncertainties.


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