Hong Kong Applied Science and Technology Research Institute Company, Limited

Xiaoyong Hu

Ziyang Gao

Tak Lok Shum

Zhou Li

Yuxie Cheng

A start-up routine for a Switched-Mode Power Supply (SMPS) gradually increases the duty cycle while reducing an initial dead time to a final optimal dead time for normal operation. Reliability is improved by the larger initial dead time that reduces ringing in switching transistors during low-voltage conditions early in the start-up sequence. Efficiency is improved by reducing the optimal dead time as voltages approach operating levels. The initial dead time is pre-calculated as a function of the input voltage and initial duty cycle. Optimal dead times are pre-calculated as a function of output voltage and output current. The optimal dead time is adjusted for each iteration of a second loop that also increases duty cycle until the target operating output voltage is reached. Pre-calculated dead times are based on the time required to fully charge and discharge parasitic drain-to-source capacitances in the switching transistors in the SMPS circuit.

Adaptive dead-time control of a synchronous buck converter

An assembly for power converting includes a circuit board, a power switching circuit mounted on the circuit board, an inductor coil that includes a winding and two ends, a magnetic core that is surrounded by the winding of the inductor coil, and a magnetic mixture that encapsulates the circuit board, the power switching circuit, the inductor coil and the magnetic core. The winding of the inductor coil is stacked above the power switching circuit and is sufficiently large to fill up a size of the assembly.

Power converter

Two or more power converters are connected in parallel to supply power current to a joining node through connecting resistors. An output voltage before the connecting resistor in each power converter is sampled and divided by a sampling ratio to generate sampled voltages for each power converter. A current sharing circuit for each power converter receives the local sampled voltage and another sampled voltage from another power converter. The current sharing circuit generates an adjustment voltage that is injected into a feedback loop. The adjustment voltage modifies the output voltage of the power converter, adjusting and balancing the power current delivered by that power converter. Power currents from several power converters are reduced and balanced when the same sampling ratio is used for all power converters. Current hogging by one power converter is prevented.

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Shenzhen, China

Xiaoyong Hu