An Online Noninvasive Estimation Method of Electrolytic Capacitor for Boost Converters

The aluminum electrolytic capacitor (AEC) plays a key role in power electronic converter, but it is the most vulnerable component in the DC-DC converter. Throughout its short lifespan, the equivalent series resistance (ESR) will increase with the AEC aging. Therefore, it is important to monitor the ESR for ensuring the normal operation of a DC-DC converter. For a boost converter operating on discontinuous conduction mode and continuous conduction mode, an online noninvasive ESR estimation method was proposed in this paper. Based on the expression derivation of the output voltage, the ESR can be estimated by sampling the output ripple voltage at three specific moments. The proposed method is a noninvasive method, which does not require the current sensors. This method can be used in the discontinuous conduction mode and critical conduction mode. The simulation results verify the effectiveness of the proposed method.