Active stabilization of a poorly damped input filter supplying a constant power load

Abstract

The presence of an LC input filter in an electrical system often results in degradation of dynamic performance and instability of the system. This paper addresses the global stability study of an electrical system comprised of a DC power supply, an LC Filter and an actuator (inverter -Permanent Magnet Synchronous Motor or induction motor). Circle Criterion is used to study the global stability of the system. In the proposed approach the control structure of the electrical system is slightly modified to implement a nonlinear stabilization structure for improving large signal stability of the system and thus allows reducing the DC link capacitance value. An electrical system consisted of an LC input filter connected to an inverter-PMSM designed for aircraft application is treated as an illustrative example.Nomenclature power current voltage Ω rotor angular speed Γ torque dc-link input voltage dc-link input current dc-link output voltage dc-link output current dc-link capacitance dc-link resistance dc-link inductance resonant pulsation frequency line inductance of three phase power supply serial equivalent resistance of power supply I-INTRODUCTIONAn inverter motor drive system connected to the grid through an L-C filter and a rectifier may lead to the instability of the dc-link voltage when reducing dc-link capacitance or increasing the inductance of the LC filter [1][2][3][4]. Electrical drives in aircrafts constitute a practical example with long dclink cable and small inverter capacitors. Indeed, the problem of interaction between two electrical systems in cascade is well known and a lot of work has already been published to explain this phenomenon but essentially in the case of DC/DC converter in cascade with their input filter [5][6][7][8][9][10]. Concerning the interaction between the power supply stage and the inverter motor drive system, some work has already been published for DC/AC applications. In [11], a nonlinear compensation structure is proposed to ensure dc-link stabilisation. Nevertheless as discussed in [12], the drawback of this method is to suppose a perfect control of the torque (disturbance rejection as well as reference tracking) which is not always verified and can lead to instability of the dc-link voltage. In [2,12], the authors take into account the torque dynamic thanks to a simplified dynamic model and propose a modification of the torque control loop to stabilize the dc-link voltage. Even if this solution allows stabilizing the dc-link voltage, it decreases the dynamics performances of the torque loop especially as regard to perturbations rejections. In [13], another approach for drives based on Brushless DC motors (BLDC) is proposed. The authors give a simplified expression for the system input impedance and propose a frequency highpass stabilization block without discussing about the robustness with respect to the measurement noise. In [14] an oscillation compensation technique for linear system is presented for stability investigation.In this paper we present a nonlinear stabilizatio...

Power Flow Control and Network Stability in an All-Electric Ship

“…15 and relies on the same principle: emulate a virtual impedance by control. This approach was discussed in [59]- [62].…”

“…In these cases, the impact of the stabilizing action on the stability of the new system is assessed by studying the influence of the control on the input impedance of the load. Another approach was presented in [59], where an exact input/output linearization of the original nonlinear system was proposed. The authors claim that the advantage of this method is to offer a stabilizer whose size is independent of the operating point, thus ensuring the large signal stability of the system and not only around an operating point.…”

Lyapunov function‐based improved switching command for a boost converter with an inductor–capacitor input filter

“…However, the LC filter may generate instabilities because of the interactions among the filter and converter [7–9]. This phenomenon limits the maximum output power transfer through the LC filter [8–10]. To avoid this problem, several analysis tools have been developed to evaluate the eigenvalues using averaged or discrete models [9].…”

“…To avoid this problem, several analysis tools have been developed to evaluate the eigenvalues using averaged or discrete models [9]. Moreover, several methods to stabilise the system have been proposed, including passive and active methods [7–10]. Nevertheless, even when the stabilisation owing to the passive component is consistent and straightforward, the weight and volume of the entire system increase, thereby incurring losses [11].…”

Distributed stabilization in DC hybrid power systems

“…Methods are based on synergetic control [13], [14], sliding-mode control [14] and phase-plane analysis [15]. In [11], [16], [17], [18], large signal stability of systems was considered and nonlinear compensation structure is proposed to ensure DClink stabilization. A method, based on the Takagi-Sugeno multi-modeling and Finsler's lemma was proposed in [19] that can be used to study the large signal stability of the DClink in cascade systems.…”