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Uninterruptible Power Supplies
Published in Ali Emadi, Abdolhosein Nasiri, Stoyan B. Bekiarov, Uninterruptible Power Supplies and Active Filters, 2017
Ali Emadi, Abdolhosein Nasiri, Stoyan B. Bekiarov
In instantiations voltage feedback SPWM control, the output voltage is continuously compared with the reference signal-improving dynamic performances of the UPS inverter [63]. The speed of the dynamic responses depends only on the switching frequency, which cannot be made very high in higher power rating applications. Another disadvantage of this approach is that harmonics are generated in the output voltage around the switching frequency. In addition, the dynamic response is still not fast enough. Another approach is based on digital control techniques. Discrete-time control strategies are generally of two types: optimum PWM techniques [64] and deadbeat techniques [58–61]. In digital optimum PWM techniques, the switching angles are calculated in order to minimize specific harmonics in the output. These techniques have a very good steady-state performance with linear loads; but with nonlinear and step-changing loads, their performance is unsatisfactory [65]. The deadbeat control technique shows better performance with nonlinear loads. In this technique, based on predicted and sensed output voltage, the exact length of the switching interval can be computed in real time so that the exact value of the desired output voltage can be obtained. The disadvantages of the deadbeat control technique are that it is computationally intensive and, for this reason, it is feasible only at relatively low frequencies. It also shows poor performance with step-changing loads.
Review of Digital Control Techniques in Power Electronics
Published in Ali Emadi, Alireza Khaligh, Zhong Nie, Young Joo Lee, and Digital Control, 2017
Ali Emadi, Alireza Khaligh, Zhong Nie, Young Joo Lee
The deadbeat control scheme has the disadvantages of being highly sensitive to parameter and load variations and requiring a large peak-to-average ratio of control signals to achieve the effect. The main advantage of the digital sliding mode control (DSMC) scheme is its insensitivity to parameter variations and load disturbances, which leads to invariant steady-state response in the ideal case, while its disadvantages are that it is not easy to find an appropriate sliding surface and its performance will be degraded with a limited sampling rate [9], [43], [44].
The deadbeat current control of MMC rectifier with wide range output voltage
Published in Rodolfo Dufo-López, Jaroslaw Krzywanski, Jai Singh, Emerging Developments in the Power and Energy Industry, 2019
Lingzhi Yi, Xiaohui Huang, Luo Liu, J.i.e. Li
Deadbeat control has many advantages, such as simple control algorithm, a small amount of calculation, fast calculation speed, high tracking accuracy, and fast dynamic response (Fu X, et al. 2009). The use of deadbeat control for MMC controller design can greatly reduce coordinate transformation and PI regulators while reducing the computational complexity of the control system (Deng X, et al. 2014, Rong F, et al. 2017). Therefore, this paper proposed a Deadbeat current control method for wide voltage range output MMC rectifier to optimizer the control system.
Harmonics mitigation for Supercapacitor and Active Power Filter based Double Closed Loop Control
Published in International Journal of Electronics, 2021
Yongfeng Ju, Muhammad Shahzad Nazir, Ahmed N. Abdalla, Ji Jie, Tiezhu Zhu
Many researchers proposed APF topology due to its superior performance in harmonic mitigation (Cheng & Lu, 2017; Jia et al., 2015; Malik et al., 2020; Tareen et al., 2017; Tawfiq et al., 2020). Kale and Ozdemir (2005) proposed a random variable loop wide hysteresis current tracking control method for active power filters, which effectively reduced switching losses and achieved good harmonic compensation effects (Kale & Ozdemir, 2005). Salam et al. (2006) (Salam et al., 2006) proposed an improved deadbeat controller that combines the voltage correction algorithm and the current correction algorithm, which improves the performance of fast-changing currents. However, the deadbeat control that still relies on the precise mathematical model of the system and has poor noise immunity. Li et al. (2020) (Li et al., 2020) adds an energy storage unit on the DC side of the conventional APF. The energy storage unit is charged first during operation, and then the given current signal is output by the APF to achieve reactive power compensation and harmonic control functions, but it does not output active power (Mishra et al., 2020). Gowthaman and Anita (2019) studied an improved APF based on superconducting energy storage, whose DC side power supply is composed of AC/DC link, DC/DC link and superconducting magnet, which not only has reactive power compensation, harmonic control function (Gowthaman & Anita, 2019). It can also provide active power output, but the DC side superconducting energy storage system has complicated control and high construction cost. Mansor et al. (2020) propose a battery energy storage system that meets the multi-functional needs of the microgrid. The main circuit structure is composed of series inverters and parallel inverters (Mansor et al., 2020). Hosseini and Barakati (2019) established the frequency domain model of boost APF and performed the sensitivity analysis of the compensation current on the secondary even-order harmonic modulation parameters, but did not conduct in-depth research and verification on the control characteristics (Hosseini & Barakati, 2019). Osman et al. (2019) conducted open-loop experiments to study the reactive power and harmonic comprehensive compensation characteristics of single-phase buck APFs and discovered the coupling effect of different even-order modulation waves on the same odd-order harmonic current (Osman et al., 2019). Therefore, the control strategy of the device still complicated task for the series compensation voltage harmonics, parallel compensation current harmonics and determine the appropriate amount of active/reactive power (Babu et al., 2019; Rao et al., 2020; Sarriegui et al., 2016).