Online condition monitoring and fault detection of large supercapacitor banks in electric vehicle applications

Abstract

Supercapacitor is being widely used in electric transportation applications, particularly in electric vehicles (EVs). In the EV, the supercapacitor mainly serves as energy storage system for accelerating the vehicle and/or capturing the braking energy due to its prominent features such as high power density and long life cycle. However, during the vehicle braking and/or accelerating, deep and fast supercapacitor charging-discharging cycles increase the electric and thermal stresses on the supercapacitor bank. Under such circumstances, condition monitoring of the supercapacitor bank is essential in EVs for safe operation of the storage system. In this paper, an effective method for condition monitoring and fault diagnosis of the supercapacitor banks is proposed. First, it is shown that the equivalent series resistance (ESR) and double-layer capacitance (CDL) can be used as the key signatures for indicating the state-of-health. Subsequently, the recursive extended least-square algorithm (RELS) is used for online estimation of the ESR and capacitance of the supercapacitor bank. Based on a residual signal which is defined as the difference between the voltages of the supercapacitor bank and RELS algorithm, the abnormal conditions of the supercapacitor bank are distinguished. Experimental results are presented to confirm the feasibility and precision of the proposed method.

Hardware implementation of an improved control strategy for battery–supercapacitor hybrid system in electric vehicles

“…Analogously, Fig. 3 shows a simple ( R sc − C sc ) dipole, validated with a least‐squares algorithm, used to illustrate the electric behaviour of the supercapacitor module [36]. The R sc represents the loss in joules inside the device and C denotes the amount of stored energy [37].…”

Fault Diagnosis and Identification of Power Capacitor Based on Edge Cloud Computing and Deep Learning

“…If there is no fuse protection, the oil tank will break. After discharging, the film of full film capacitor will be affected by high temperature, and melting will make two-electrode short-circuit contact without arc discharge or gas explosion, so full film capacitor shall be used for explosion proof [17]. (5) Capacitor heating: when there are harmonics in the system, the harmonic current will damage the capacitor to a certain extent, which will aggravate the related loss of the insulation medium of the capacitor, so it is easy to make the insulation layer age rapidly; sometimes, it may bring the related risk of thermal breakdown, which will have a bad impact on the safe operation of the capacitor to a large extent, in the case of harmonics, the electrode of the capacitor.…”

Power transformer differential protection based on least squares algorithm with extended kernel

“…The parameter n must necessarily be greater than m. In the OLS algorithm, the main goal is to find an estimation y^, which approximates y with a minimal sum of the squared error loss function. The optimal set of the parameters can be obtained as follows: Although the OLS algorithm can be straightforwardly implemented through (1) and 2, it is not efficient for online applications, where the estimation needs to be updated for each sampling point [17,18]. Besides, it is not possible to predict the dynamic of the measurement noises by the OLS method.…”