This paper proposes a transformerless T-type modular multilevel DC-DC converter (T-MMDC) with quasi-square wave (QSW) modulation for high-voltage direct current (HVDC) grid applications. The proposed topology employs asymmetric three-arm configurations to achieve direct power conversion without isolation transformers. Analytical models are developed to characterize the inherent power flow dynamics and energy balance constraints. Operational principles under QSW modulation are systematically investigated, including derivations of voltage-current relationships and commutation mechanisms. A hierarchical control framework integrating energy balancing and commutation strategy is designed to ensure stable power conversion. Comprehensive simulations of a 500MW, 320kV-100kV system demonstrate stable operation with efficient energy transfer. Experimental validation using a 5kW, 750V-250V prototype confirms the methodology's effectiveness under practical non-ideal conditions. Results substantiate the proposed topology as a viable solution for utility-scale renewable energy integration and multi-voltage-level transmission in HVDC networks.

The grid-forming (GFM) converter serves as a crucial link between the grid and generation in large-scale power-generation systems. However, unintentional grid faults risk the transient stability of GFM converter, which severely impacts the reliability of systems. This paper introduces the critical parameter characterization for power synchronization, which can stabilize the GFM converter over grid faults. The foundation of this work lies in the analysis of the effect of the crossing coupling between the power loops on transient stability. It reveals that, the transient terminal voltage drop generated by the crossing coupling will give rise to jeopardize the transient stability but can be alleviated by adjusting droop-control parameters. This insight facilitates the derivation of the critical parameters for a stable transient operation. With the derived parameters, the GFM converter can operate stable under grid faults. Finally, experiments are conducted to confirm the theoretical expectations.

This paper presents a 96.5% peak efficiency adaptive ON-time controlled buck converter with 0.001-500 mA load range for internet of things. A novel positive feedback controlled comparator is presented, with its bias current dynamically increased to accelerate the transient responses while maintaining low power consumption. Besides, the power gating scheme and a sub-nA voltage reference is implemented to achieve ultra-low overall quiescent current, leading to an outstanding conversion efficiency. Designed and simulated in a 0.18μm CMOS process, the prototype shows an undershoot voltage of 43 mV and recovery time of 2.8 µs during a load transient from 10 μA to 500 mA, with a total quiescent current of 60 nA. The proposed design shows efficiencies of 95.4%, 96.5% and 91.2% when the load current is 10 μA, 100 μA, and 500 mA, respectively.

This article presents a novel Dickson hybrid boost converter for thermoelectric energy harvesting that utilizes a fixed ratio switched-capacitor (SC) converter combined with a traditional switched-inductor design. This unique approach makes high conversion ratio (CR) more attainable. Besides, the converter features an on-chip LC oscillator for cold-starting the harvester without requiring any external components. To improve the efficiency of the harvester, a lookup table-based maximum power point tracking (MPPT) and a zero current detection (ZCD) circuit are also implemented. The prototype was designed and fabricated using the 55 nm low power (LP) CMOS process, with a compact 5.6-$\mu $H inductor. Measurement results verify that the harvester can cold start at an open-circuit voltage ofV$_{\mathbf{TG}}$$=$110mV, achieve a peak efficiency of 90.5% atV$_{\mathbf{TG}}$$=$140mV, and maintain operation at a 5-mV input voltage with a 200-nA load. Furthermore, the converter maintains end-to-end efficiencies above 80% for a wide range ofV$_{\mathbf{TG}}$$=$40$\sim$200mV. With a wide input range of 5$\sim$100mV and load range of 200nA$\sim$4.52mA, the proposed converter represents a significant improvement in performance over previous state-of-the-art designs, with a decent power efficiency, compact form factor and wide output power range.

This article presents a wide voltage and current range bypass-assist series-capacitor power converter for data centers and automotive applications. The overall power converter consists of a 2:1 charge pump (CP) front stage and a 6-level bypass-assist series-capacitor rear stage, by which the proposed design resolves the troublesome duty cycle limit that a typical series-capacitor converter usually faces. Therefore, the output regulation range is significantly extended and only one inductor is required. Besides, since the converter operates like a simple Buck converter with an equivalent input of$V_{\mathrm {IN}}$/12, an easy pulse-width-modulation (PWM) and pulse-frequency-modulation (PFM) compatible design is implemented and the efficiency greatly enhanced over a wide load range. The prototype was fabricated using the 180 nm bipolar-CMOS-DMOS (BCD) process and demonstrates a broad operating voltage range of 36~55-V input and 0.6~2.5-V output with 1.5mA~5A load range. For a typical 48-V input, the measured peak efficiencies of 2.5, 1.8, 1 and 0.6-V output are 93.1%, 88.1%, 86.6% and 82.7%, respectively. Additionally, when the load decreases to 30-mA, the proposed converter still achieves efficiencies of 88%, 82%, 80% and 70%, respectively.

This paper presents a Dickson hybrid boost converter with an on-chip cold starter for thermoelectric energy harvesting. The proposed harvester achieves both high power efficiency and low inductor volume. An on-chip LC oscillator cold starts the harvester without external components. Besides, a lookup table based maximum power point tracking (MPPT) improves the end-to-end efficiency in a wide input range. Designed and simulated in a 0.13 $\mu$m CMOS process, the harvester achieves a maximum end-to-end efficiency of 93.9% with a 5.6 $\mu$H inductor. The circuit cold starts at an input of 70 mV and the minimum operation voltage is as low as 6 mV with a 100 nW load.

In this paper, a separation test method for eliminating the effects of different current densities on the bond wires is proposed. The separation test method makes it possible to study the effect of different current density on the fatigue damage of bond wires without changing the temperature swing and average temperature during the test. By analyzing the output characteristics of the linear region of MOSFET, the constraint relations among the gate voltage, on-state voltage drop and junction temperature are revealed in this paper. The one-to-one correspondence between gate voltage and conduction power loss can be used to adjust the current density under fixed temperature swing and average temperature. The commercial Silicon Carbide (SiC) MOSFET modules are tested to experimentally verify the proposed method. Finally, the effectiveness of proposed test method is validated by the experimental results.