The paper investigates a control approach for achieving reliable zero-voltage switching transitions within the entire operating range of a conventional nonisolated bidirectional dc-dc converter that utilizes synchronous rectification. The approach is based on operation in the discontinuous conduction mode with a constant reversed current of sufficient amplitude, which is achieved by load-dependent variation of the switching frequency. This paper focuses on the obtained resonant voltage transitions and provides analytical models for determining the reversed current and timing parameters that would ensure safe, reliable, and highly efficient operation of the converter. In addition, the proposed approach solves the synchronous transistor's spurious turn-on and body diode reverse recovery induced issues, does not require any additional components or circuitry for its realization, and can be entirely implemented within a digital signal controller. The effectiveness and performance of the presented control approach was confirmed in a 1-kW experimental bidirectional dc-dc converter that achieved 97% efficiency over a wide range of output powers at switching frequencies above 100 kHz.
COBISS.SI-ID: 18799382
This paper presents a current sensing principle appropriate for use in power electronics’ converters. This current measurement principle has been developed for metal oxide semiconductor field effect transistor (MOS-FET) and is based on UDS voltage measurement. In practice, shunt resistors and Hall effect sensors are usually used for these purposes, but the presented principle has many advantages. There is no need for additional circuit elements within high current paths, causing parasitic inductances and increased production complexity. The temperature dependence of MOS-FETs conductive resistance is considered in order to achieve the appropriate measurement accuracy. The “MOS-FET sensor” is also accompanied by a signal acquisition electronics circuit with an appropriate frequency bandwidth. The obtained analogue signal is therefore interposed to an A-D converter for further data acquisition. In order to achieve sufficient accuracy, a temperature compensation and appropriate approximation is used. The MOS-FET sensor is calibrated according to a reference sensor based on the Hall-effect principle. The program algorithm is executed on 32-bit ARM M4 MCU, STM32F407.
COBISS.SI-ID: 18853910
A pulse-density-modulated (PDM) flyback-based microinverter with a high-frequency AC (HFAC) link and an active decoupling circuit is proposed. The converter's structure and basic operating principle are analysed. The advantages of utilising an active decoupling circuit and the demand for using pulse-density modulation are explained. The operation of the proposed microinverter has been verified by experiment.
COBISS.SI-ID: 18525718