ZERO-CURRENT AND ZERO-VOLTAGE SWITCHING PWM BOOST FULL-BRIDGE CON VERTER

This paper proposes a zer o current and zero voltage switching (ZCZVS) PWM Boost full bridge (FB) conve rter. With series inductors, the leading switches can realize zero current swit ching (ZCS) in a wide load range using the energy of the output capacitor. Ma king use of parasitic capacitors of the lagging switches and parallel auxiliary i nductance with the primary winding of the transformer, the lagging switches can realize zero voltage switching (ZVS) under any load. Compared with the ZCS PWM Boost FB converter, the new converter has no current duty cycle loss. Operat ional principle and parameter design are analyzed. Experimental results verify the effectiveness of the proposed converter.

SOFT SWITCHED SYNCHRONOUS RECTIFIER WITH PHASE-SHIFTED FULL BRIDGE CONVERTER AND ITS SMALL-SIGNAL ANALYSIS

By using the output inductors and body capacitances without adding any component compared with hard switching synchronous rectifier,the topology of a soft switched synchronous rectifier with phase-shifted full bridge zero voltage switching DC/DC converter is proposed. The converter efficiency is maximized due to soft switching of the full bridge MOSFETs and the synchronous MOSFETs, and also the low conduction loss of synchronous MOSFET. The operation principles of the circuit are analyzed in detail and the small-signal model is derived, also the converter dynamic characteristics are analyzed. Frequency responses of transfer functions under different values of transformer primary leakage inductance are discussed. The experimental results were obtained from a 400 V input and 100 A/12 V output DC/DC converter operating at 100 kHz. The results show that the converter efficiency is 2% higher in rated power than traditional diode rectifier.

Design and performance of an EMI filter to reduce conducted EMI in an isolated full bridge buck converter power supply

EMI Filter Design and Performance for isolated full bridge buck converter is developed in this paper. In order to design a high performance EMI filter, many issues need to be considered beforehand. Some important issues including accurate model of converter components, parasitic elements, its effect on EMI noise and impedance mismatch are included in this paper. A numerical prediction of EMI/EMC has the potential to evaluate EMI performances at the design stage and before prototyping. It can also help reduce the post-prototype EMC cost by minimizing late redesign and modifications of a design implementation. Saber simulator is used to analyze the EMI noises and EMI filter’s performance. Conducted EMI noise measurement and EMI filter design of isolated full bridge buck converter has been achieved while successfully satisfying the FCC class B limits in the frequency range from 150 kHz to 30 MHz. Simulation results are compared with experimental data and the effectiveness of the EMI simulation approach is demonstrated.

Improved Full Bridge Converter with Low Peak Voltage on Rectifier Diodes

To suppress peak voltage on rectifier diodes in a full bridge( FB) converter,the mechanism of peak voltage was analyzed and an improved FB converter was proposed. One reason for peak voltage is the resonance of the transformer's leakage inductance and the rectifier diodes' junction capacitances. The other reason is that the fast reverse recovery current of the rectifier diodes flows through the transformer's leakage inductance. An H bridge composed of four diodes,an auxiliary inductance, and a clamping winding were adopted in the proposed converter,and peak voltage was suppressed by varying the equivalent inductance, principally in different operating modes. Experimental results demonstrate that the peak voltage of rectifier diodes decreases by 43%,the auxiliary circuit does not lead to additional loss, and the rising rate, resonant frequency,and amplitude of the rectifier diodes' voltage decrease.Peak voltage and electromagnetic interference( EMI) of rectifier diodes are suppressed.

A new variable-mode control strategy for LLC resonant converters operating in a wide input voltage range

This paper proposes a new variable-mode control strategy that is applicable for LLC resonant converters operating in a wide input voltage range. This control strategy incorporates advantages from full-bridge LLC resonant converters, half-bridge LLC resonant converters, variable-frequency control mode, and phase-shift control mode. Under this control strategy, different input voltages determine the different operating modes of the circuit. When the input voltage is very low, it works in a full-bridge circuit and variable frequency mode(FB_VF mode). When the input voltage rises to a certain level, it shifts to a full-bridge circuit and phase-shifting control mode(FB_PS mode). When the input voltage further increases, it shifts into a half-bridge circuit and variable frequency mode(HB_VF mode). Such shifts are enabled by the digital signal processor(DSP), which means that no auxiliary circuit is needed, just a modification of the software. From light load to heavy load, the primary MOSFET for the LLC resonant converter can realize zero-voltage switching(ZVS), and the secondary rectifier diode can realize zero-current switching(ZCS). With an LLC resonant converter prototype with a 300 W rated power and a 450 V output voltage, as well as a resonant converter with 20–120 V input voltage, the experiments verified the proposed control strategy. Experimental results showed that under this control strategy, the maximum converter efficiency reaches 95.7% and the range of the input voltage expands threefold.

Preliminary Design of Pressure Torque Separation Sensor for Drilling Bit

The working state of drilling bit is a critical issue in the drilling process. The preliminary design of pressure and torque separation sensor for drilling bit is expatiated herein. The sensor unit is composed of the elastic unit and the Wheatstone full bridge. Under composited load, the theoretical analysis about separating the axial force and torque of drilling bit is discussed firstly. The separation has been achieved by using the Wheatstone full bridge pasted onto the elastic unit. Then the transversal and axial strains distribution of elastic unit has been calculated and analyzed by ANSYS software, when the bit is under axial force and torque. Based on the calculation and analysis results, the sensitivity and accuracy of the sensor's whole measurement chain can be reckoned. Meanwhile, the calculation and analysis results can also give good suggestion about the positions where the strains gauge should be pasted. Finally, it has been proved that this solution can meet the preset requirements very well.

Development and testing of high precision and stability power supply for high energy photon source

Purpose The high energy photon source(HEPS)is the fourth-generation synchrotron photon source.Compared with the third-generation synchrotron photon source,the brightness is 100-1000 times higher,and the electron emittance of the storage ring is low to the diffraction limit of light.Through physical calculations,it is required that the stability of the storage ring quadrupole magnet power supply be better than 10 ppm,and the accuracy of output current be better than 80 ppm.This high demand for technical parameter poses a challenge to the development of high precision and stability power supplies.Methods The main circuit topology of the power supply adopts a phase-shifted full bridge soft switching scheme,which avoids interference caused by switching noise and improves power stability and efficiency.The high-precision digital power supply controller based on FPGA improves the sampling speed and control accuracy of the power supply,and the constant temperature control circuit ensures that the output current of the power supply meets the requirements of HEPS for power supply performance.Results In the batch testing section,a testing facility was built to test the stability,accuracy,repeatability,voltage ripple,and other parameter of high precision and stability power supplies.After a year and a half of testing,the performance tests of 1066 power supplies,including linear accelerators power supplies,booster power supplies,storage rings power supplies,dipole and quadrupole combined power supplies,dipole and quadrupole power supplies,were completed.The results all met and exceeded the design specifications.Conclusions The HEPS high precision and stability power supply meets the design requirements in terms of current stability,accuracy,repeatability,voltage ripple,and other aspects.The batch test results show that the power supply performance using the full bridge phase shifting soft switching technology combined with high-precision digital controller scheme is excellent,and the power supply consistency is good,providing a guarantee for the successful operation of HEPS in the future.

Design and development of strip electrode power supply for HEPS wiggler

Purpose The high-energy photon source(HEPS)is the first fourth-generation synchrotron photon source in China(Jiang et al.in Sci Sin Phys Mech Astron 44:1075-1094,2014).The strip electrode and its power supply provide necessary hardware support for correcting the magnetic field of the wiggler as reported by Zhao and Yin(Particle accelerator technology,Higher Education Press,Beijing,2006).The design of the conventional power supply for accelerators,with a large output current and high output voltage,making it easy to achieve high stability of the output current.The strip electrode power supply poses difficulties in achieving high stability due to its small output current and voltage.Because of size limitations,as well as the requirements of the power architecture,there are currently no commercial products for this type of power supply.Methods Designed and developed 32 strip electrode power supplies.Considering the large number of power supplies and limited space,a rack structure design was adopted,placing all power supplies in one rack.The main circuit of the power supply adopts a full bridge transformation structure(Chao et al.in Radiat Detect Technol Methods 6:470-478,2022),and the control scheme adopts full digital control based on FPGA(Long and Cheng in At Energy Sci Technol 43:780-784,2009).The power supply has two control modes:local operation and remote operation as reported by Lu(Particle accelerator technology,Hunan University,Changsha,2010).Results The test shows that all power supplies meet the indicator requirements,with a stability of less than 100 ppm.Conclusions The strip electrode power supply can effectively correct the multipole integral field error and improve the integral field performance of the wiggler.