Capacitance Estimation Method of DC-Link Capacitors for BLDC Motor Drive Systems

Abstract

-This paper proposes a capacitance estimation method of the dc-link capacitor for brushless DC motor (BLDCM) drive systems. In order to estimate the dc-link capacitance, the BLDCM is operated in quadrant-II or -IV among four-quadrant operation. Quadrant-II and -IV are called reverse braking and forward braking, respectively. During the braking operation of the BLDCM, the capacitor is charged by the phase current and then the voltage is increased during the braking operation time. The capacitor current and voltage can be obtained by using the phase current sensor of BLDCM and the dc-link voltage sensor. The capacitance and be easily obtained by the voltage equation of the capacitor. The proposed method guarantees the reliable and simple calculation of the dc-link capacitance without additional hardware system except several the sensors already installed for the motor control system. The effectiveness of the proposed method is verified through both the simulation and experimental results.

A positiveoutput‐superlift Luo converter fed brushless DC motor drive using alternative energy sources

“…The main reason to estimate the DC link capacitor of VSI is that the harmonic content present in the AC supply is reflected on the DC side as a prior harmonic in the three-phase supply system. 16 The minimum and the maximum speed for the BLDC motor to pump water application can be calculated by finding out the fundamental frequencies of output voltage of VSI. The two frequencies (ω max and ω min ) are more significant since they are used to compute the DC-link capacitor value.…”