Laboratory Demonstration of Closed-Loop 30 kW, 200 V/900 V IGBT-Based LCL DC/DC Converter

Abstract

Abstract--The inductor-capacitor-inductor (LCL) DC/DC converter has been extensively studied for high power and stepping ratio because of elimination of internal transformer, lower footprint/weight, higher efficiency, and most importantly providing DC fault isolation from both DC sides. This paper presents a two-channel, two-layer controller including two inner current loops, which is symmetrical for each bridge of LCL DC/DC. The real-time implementation of control scheme and its performance in normal conditions and during transient DC faults at both sides are studied on a 30kW 200V/900V 1.7 kHz prototype. The prototype development is presented in some depth. The experimental results show that the converter with closed loop control operates well at full power and under fast power reversal. Further DC fault testing concludes that there is no need for blocking since the internal voltage and current variables are within the rated values. Detailed study of converter losses is performed and results show that full power efficiency is around 93.4%.

A Method to Monitor IGBT Module Bond Wire Failure Using On-State Voltage Separation Strategy

“…We then applied the separation strategy of on-state voltage to IGBT module bond wire failure prediction, as shown in Figure 9. V ce-mea is the on-state voltage measured under on-line conditions, and V package-cal is the package voltage calculated using Equation (10) under the same conditions after acquiring I c and T j information. V package-hea , V package-2liftoff , and V pacakge-4liftoff are the package voltages measured under off-line conditions (healthy, two bond wires liftoff, and four bond wires liftoff, respectively):…”

“…We then tested the on-state voltage of another IGBT module (three bond wires cut off). With Ic = 75 A and Vce-mea = 1.6091 V, Equations (6), (9) and (10) yield Vce-th = 0.6056 V, Von-chip = 0.6898 V, Vpackage-cal = 0.3137 V, respectively, as shown in Figure 10. The diagnosis strategy shows it can be classified as the middle stage of the bond wire failure, the same status as the real aging process.…”

“…In some fields, IGBT modules have to endure more than five million power cycles during their lifetimes [9], which makes failure inevitable. The failure rate of IGBT modules also increases in harsh operating environments and with higher voltage levels [10,11]. Therefore, it is important to study the aging mechanism of IGBT modules and propose an accurate method to monitor the aging process to improve the reliability of the whole power electronic converter.…”