DC-Link Voltage Coordinated-Proportional Control for Cascaded Converter With Zero Steady-State Error and Reduced System Type

Abstract

Abstract-Cascaded converter is formed by connecting two subconverters together, sharing a common intermediate DC-link voltage. Regulation of this DC-link voltage is frequently realized with a Proportional-Integral (PI) controller, whose high gain at DC helps to force a zero steady-state tracking error. Such precise tracking is however at the expense of increasing the system type, caused by the extra pole at the origin introduced by the PI controller. The overall system may hence be tougher to control. To reduce the system type while preserving precise DC-link voltage tracking, this paper proposes a coordinated control scheme for the cascaded converter, which uses only a proportional DC-link voltage regulator. The resulting converter is thus dynamically faster, and when compared with the conventional PI-controlled converter, it is less affected by impedance interaction between its two sub-converters. The proposed scheme can be used with either unidirectional or bidirectional power flow, and has been verified by simulation and experimental results presented in the paper.

Single‐stage buck‐boost off‐grid inverter with feedforward control

“…The control block diagram using the feedforward control is shown in Figure 4. Since the full-bridge inverter works at the line frequency, the full-bridge inverter can be equivalent to a load (R load ), given in (9). The transfer function of the compensator is shown in (10).…”

“…7,8 However, the output voltage accuracy is low with the PI control, so the loads that require high voltage accuracy cannot be powered. 9 Therefore, the proportional resonance (PR) control was proposed to improve the output voltage accuracy. 10 The system gain can be infinitely amplified by using the PR control at a constant frequency, so the output voltage accuracy is high at a specific frequency.…”

“…The proportional‐integral (PI) control is widely used in the inverters 7,8 . However, the output voltage accuracy is low with the PI control, so the loads that require high voltage accuracy cannot be powered 9 . Therefore, the proportional resonance (PR) control was proposed to improve the output voltage accuracy 10 .…”

Design of A Fuzzy Controller for Solar Pv Array Fed Water Pumping Systems

“…The simulation outcomes clearly showed that the linearized system neatly illustrates the nonlinear system round the same working conditions and PI controllers realize desired performance and robustness. In (Tian, Loh, Deng, Chen, & Hu, 2016), the PI controller achieved the modification of dc-link voltage. A significant improvement in dc helps to make the tracking error stable.…”

Analysis of Closed Loop control of Cascaded Three Phase Grid Tied Inverter using Fuzzy Logic Controller

“…In spite of various converters available, Dual Active Bridge (DAB) converter is mostly preferred converter for integrating EV to the grid. DAB is mainly preferred because of its bidirectional power flow, with symmetrical structure, soft switching and high-power density [3], [4]. So, this converter is preferred for cascading with an inverter.…”