A novel harmonic elimination approach in three-phase multi-motor drives

Abstract

Abstract-Power electronics technology has been widely used for decades in the modern motor drive systems. Beyond the control flexibility, the power electronics devices (e.g., diode rectifiers) are also the main harmonic source to the grid due to their nonlinearity, which deteriorate the power grid quality and may cause unnecessary losses in power system transformers. Both degradations are apt to occur in motor drive applications. As a consequence, it calls for advanced and intelligent control strategies for the power electronics based drive systems like adjustable speed drives in industry. At present, many industrial drives are still equipped with three-phase diode rectifiers. Thus, it is difficult to implement the prior-art harmonic control strategies for active front-ends. Moreover, the total cost and complexity has become an obstacle for these harmonic elimination approaches in multiple drive systems. Therefore, in this paper, a new cost-effective harmonic mitigation approach has been proposed for multiple drives. The proposed approach can control the generated current harmonics by benefiting of the nonlinearity of the drive units and through a novel current modulation scheme. Simulation and experimental results have validated the effectiveness of the proposed approach in terms of harmonic elimination in three-phase multi-drive systems.

Adjustable Speed Drives and power quality: Challenges and cost-effective opportunities

“…1(b)). The basic idea of the EI is to replace the bulky DC-side inductor with a relatively small one by incorporating a DC-DC converter emulating the behavior of an ideal infinite inductor [5]- [6]. In this situation, the input current (i.e., i g , abc ) will be a square-wave with 120 degrees conduction with THD i ≈30%andλ≈0.95.AsFig.2andFig.…”

Multi-Level Open End Windings Multi-Motor Drives

“…The number of available voltage vectors and voltage levels depends on K V , as listed in Table 2, affecting both the THD V and the peak amplitude V mpk of the phase voltage V mi . In particular, V mpk increases with K V , while a minimum THD V is achieved for V DC " = V DC /[(n − 1)], [24], thus, the considered 3LI+TLI system gets the minimum THD V for V DC " = V DC /2. However, V mpk maximization must be also taken into consideration, thus, a useful figure of merit in determining the optimal value of K V is Table 3, is maximized when V DC " = V DC /2.…”

“…These can be addressed by selective harmonic elimination or PWM techniques, as well as, by the addition of line reactors and tuned harmonic filters. Active power filters may also be exploited as they are able to provide a more flexible and effective attenuation of current harmonics [15][16][17][18][19][20][21][22][23][24].…”

A DC-Link Modulation Scheme With Phase-Shifted Current Control for Harmonic Cancellations in Multidrive Applications

“…In order to tackle these issues, a new DC-link current modulation scheme for multi-drive systems is proposed in this letter. The new modulation scheme is derived by adding and subtracting specific modulation levels in such a way that the total currents drawn by the rectifiers become "multi-level" [13], [14], leading to a mitigation of the current harmonics. Moreover, by phase-shifting the SCR currents, the grid current Y. Yang, P. Davari, and F. Blaabjerg are with the Department of Energy Technology, Aalborg University, DK-9220 Aalborg, Denmark (e-mail: yoy@et.aau.dk; pad@et.aau.dk; fbl@et.aau.dk).…”

“…Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org Digital Object Identifier 10.1109/TPEL.2015.2472641 quality can be enhanced in terms of a lower Total Harmonic Distortion (THD) and a mitigation of the harmonics of interest. If the modulation patterns are pre-programmed appropriately, the harmonic cancellation is enabled by a mix of the new modulation scheme and the phase-shifted current control, and it can be competitive to multi-pulse systems (e.g., 12-pulse diode rectifiers) [14]. In addition, an improvement of the harmonic cancellation strategy can be attained by optimizing the modulation patterns.…”