The resonant LLC vs. LCC converter - comparing two optimized prototypes

Abstract

Abstract²Due to the increasingly demand for highly efficient, cost-effective and low-profile applications, resonant converter topologies are massively gaining in importance. With the LCC and LLC converter, the two most promising topologies of this converter class are presented and compared within this paper. Based on their individual configuration, both converters are analyzed in the time domain revealing the first differences and similarities. Moreover, both converter topologies are optimized with respect to a low-profile notebook adapter specification for 100 W. The main focus is placed on the magnetic design of both transformers. Finally, two prototypes using completely identical layouts are developed and measurement results are discussed concerning best operation point and overall efficiency.

Analysis and design of a partial-multi-resonant LLC converter

“…In Fig. 15 the efficiency of the clamped and unclamped converter with the specification from [8] are compared. It can be seen that the efficiency of the clamped converter is lower than the unclamped one.…”

“…For comparison to an existing optimized converter the LLC converter in [8] is chosen. The input voltage is in this case limited to: 250 V ≤ U in ≤ 400 V. Whereas the nominal input voltage is set to: U in = 380 V. The output power (without burst-mode) is set to the range: 10 W ≤ P out ≤ 100 W and the output voltage is selected to U out = 19 V. The optimization shows that there are three different modes for the optimized converter (Z 0 = 80, κ = 0.4, n = 5.85, f 0 = 424 kHz) shown in Table 2.…”

Resonant Power Converters for Renewable Energy Applications: A Comprehensive Review

“…The LCC converter is an effective topology for highly efficient power converters, allowing wide operation with high performance. Because of the low switching losses, the LCC RPC can operate at higher switching frequencies while retaining high and almost constant efficiency over the whole load and input voltage range (Pawellek et al, 2011;Deepika and Elakkiya, 2014). The LCC is also the better option for high output voltages because of the presence of capacitor at the output winding.…”

“…Two large and expensive independent physical capacitors are required due to the high AC currents (Outeiro et al, 2016a). The efficiency level is just marginally higher at low input compared to high input voltage (Pawellek et al, 2011) One major drawback of LCL type SRC with inductive filter is that high voltage stresses on the output rectifier is observed (Bhatt, 2017) • Resonance capacitors must with stand high AC currents and must be specific types (Nielsen, 2013) Load variations It has a wide load variation range. Up to 20% of the full load to full load (Salem et al, 2020) It is not suitable for wide load variation, but it has a wider gain range It has a wide load variation range by 50% (Salem et al, 2017c) and from 100% to 20% of the full load (Bhatt, 2017) Voltage gain It has a high voltage gain, with a recorded voltage gain equal to 5 in Salem et al ( 2020) and 6.25 in Bhuvaneswari and Babu (2016).…”

Design of LLC Resonant Converters Based on Operation-Mode Analysis for Level Two PHEV Battery Chargers

“…Following the basic principles of circuit theory together with the normalizations in Table I, the normalized equations describing the resonant states are [13], [19], [24] …”