Magnetic Reset Research Articles

Magnetic core reset technology for high repetitve solid state linear transformer driver

Magnetic core reset technology for high repetitve solid state linear transformer driver

Analysis of Energy Transmission and Design of Additional Capacitance for a Novel Secondary Side Parallel LCD Forward Converter

For the deficiency of low utilization ratio of transformer excitation energy, complex circuit structure, low efficiency and low output power in the existing magnetic reset technology, a secondary parallel LCD forward converter which can avoid reverse charging of additional capacitor is proposed. According to the different working modes of inductors in the proposed converter, the converter is divided into different combined working modes, and the working principles of different combined working modes are analyzed in detail. At the same time, the influence of additional LCD circuit on the performance of the proposed converter is deeply studied based on the working principles of different combination modes. According to the performance analysis, the analytical expression of additional capacitance on the working mode is derived, and the optimal design scheme of additional capacitance parameters is put forward. Finally, in order to verify the effect of the additional capacitance C2 on the operation mode of the converter, an experimental analysis of the secondary parallel LCD forward converter which can avoid the reverse charging of the additional capacitor is carried out. The experimental waveform analysis verifies the correctness of the theoretical analysis and the feasibility of the design method of the additional capacitor parameters.

A Novel Secondary Side Series LCD Forward Converter with High Efficiency and Magnetic Reset

A novel secondary side series LCD forward converter with a high efficiency and a magnetic reset is proposed in this paper. Compared with the traditional forward converter, the proposed converter can transfer excitation energy to the output terminal and achieve a reliable magnetic reset of the transformer with a better working efficiency. Moreover, the proposed converter realizes the low-voltage turn-on of the switch. The operating principle and energy transmission process of the proposed converter is explicitly analyzed. It was concluded that the optimal combined working mode was Lm-DCM, L1-CCM and L2-CCM. By analyzing the energy transmission mechanism of the proposed converter in the best working mode, the parameter design scheme of the proposed converter was obtained. Finally, a prototype was built. The simulation and experimental results are presented to verify the correctness of the theoretical analysis and the feasibility of the parameter design scheme of the proposed converter. At the same time, a comparison between the proposed converter and existing converters was conducted to demonstrate the best electrical performance of the proposed converter.

A Novel Secondary Side Parallel LCD Forward Converter

Aiming at the shortcomings of the current forward converter, such as low utilization rate of excitation energy, complex circuit structure and single function of magnetic reset technology, a novel secondary side parallel LCD forward converter is proposed. By analyzing the working principle of the proposed converter, the optimal combined working mode is obtained, which can improve the energy transmission efficiency of the converter, ensure high power transmission and reduce the output voltage ripple. The energy transfer process of the optimal mode is deeply analyzed, the input–output relationship and the critical inductance expression in this mode are deduced, and the optimization of the parameters of the capacitor and inductance components in the converter is proposed. Finally, according to the parameter optimization design scheme, a prototype of the secondary side parallel LCD forward converter is developed. The experimental results of the prototype show that the proposed forward converter can not only achieve reliable magnetic reset, but also transmit the excitation energy of the converter to the load side, which effectively improves the efficiency of the converter.

High-Frequency Bipolar Solid-State LTD Based on a Self-Triggering H-Bridge

In pulsed electromagnetic field tumor ablation, a bipolar nanosecond pulsed electric field has obvious therapeutic advantages. This article proposes a bipolar linear transformer drive (LTD) source circuit topology with a self-triggering H-bridge for this application. In this topology, in the absence of a magnetic core reset circuit, high-frequency bipolar pulse output is realized by introducing an H-bridge while keeping the circuit structure simple. A self-triggered H-bridge is formed by cleverly introducing a self-triggered circuit in the H-bridge, which reduces the difficulty of circuit control. There are only two main control signals, and the sources of all the main control switches share the same ground. The self-triggered switches are self-triggered through the energy-taking capacitor, which improves the stability of the switch control. Theoretical analysis and simulation results demonstrated the theoretical feasibility of the above-mentioned topology; thus, an experimental prototype was built to test the key parameters. The entire prototype adopts a modular design, and each module consists of only four self-triggering H-bridges and one nanocrystalline magnetic core. The key parameters of the final designed prototype are as follows: voltage amplitude of ±4 kV, pulse width of 60–260 ns, pulse rising edge of approximately 11 ns, continuous operation at a maximum frequency of 10 kHz, and output of 500 kHz high-frequency nanosecond pulse.

A Bimodal Multichannel Battery Pack Equalizer Based on a Quasi-Resonant Two-Transistor Forward Converter

In the application of a long series battery group, an inter-pack imbalance is inevitable. No intra-pack cell equalizer can prevent pack-level over-discharge. A bimodal, multichannel battery pack equalizer based on a quasi-resonant, two-transistor forward converter is proposed to solve this problem and achieve a tradeoff between balancing efficiency and speed. This equalizer has two modes: pack-to-pack-group and pack-to-any-pack (P2PG&AP) mode and direct-pack-to-pack (DP2P) mode. In P2PG&AP mode, this equalizer can realize the full-switching-cycle (FSC) equalization through three balancing channels, and transfer energy from any pack to both the whole group and any pack inside the group. In addition, it can effectively clamp the transformer-induced voltage using a secondary side two-transistor magnetic reset structure (STMR) and reduce the total turns of transformer coil from 70 to 50 turns via a secondary side boost converter (SBC). In DP2P mode, this equalizer can realize zero voltage gap (ZVG) equalization. A prototype was tested at different switching frequencies and LC values to validate the theoretical analysis and optimize the bimodal hybrid operation. Experiment results including higher than 89.66% efficiency and minute-level balancing time under different pack voltage distributions show that the proposed topology demonstrates excellent balancing performance.

High Gain Boost Interleaved Converters with Coupled Inductors and with Demagnetizing Circuits

This paper proposes double interleaved boost converters with high voltage gain and with magnetically coupled inductors, while a third coupled winding is used for magnetic flux reset of the core during converter operation. The topology of the proposal is simple, it does not require many additional components compared to standard interleaved topologies, and it improves the transfer characteristics, as well as system efficiency even for high power levels. The investigation of steady-state operation was undertaken. It was discovered that the proposed converter can be designed for a target application where very high voltage gain is required, while adjustment of voltage gain value can be done through duty-cycle variation or by the turns-ratio modification between individual coils. The 1 kW prototype was designed to test the theoretical analysis. The results demonstrate that the proposed converter achieves very high voltage gain (1:8), while for the designed prototype the peak efficiency reaches >96% even when two additional diodes and one winding were implemented within the converter’s main circuit. The dependency of the output voltage stiffness on load change is minimal. Thus, the presented converter might be a proper solution for applications where tight constant DC-bus voltage is required (a DC-DC converter for inverters).

Magnetic Integrated Dual-Tube Forward Converter

This paper will be introduced to the magnetic integration technology is the excitation converter, magnetic integration technology research on the influence of the output current ripple and dynamic performance of the converter. Papers put forward integrated scheme of transformer and filter inductance, magnetic integration is derived resonant reset and integrated winding magnetic reset is the excitation converter. In analysis converter working condition is obtained on the basis of the various work phases of the converter current ripple, and points out that the output current pulse are 5 possibility for two kinds of normal shock of electric current pulse converter, analysis all kinds of electric current pulse magnetic resistance condition and smallest current ripple, the analysis of various kinds of magnetic reset under the way of magnetic integrated normal shock steady-state equivalent inductance of the converter and dynamic equivalent inductance, magnetic integration technology research for the steady-state performance and dynamic performance of the excitation converter.

Analysis Design and Experimental Verification of a Two-Switch Forward Converter

A forward converter is an isolated DC-DC converter widely used in switching power supplies with output power ratings ranging from 50W to 400W. The conventional forward converter requires a transformer with a tertiary winding to assist in magnetic core reset and subjects its power switch to a high voltage at turn-off. These shortcomings are eliminated in the two-switch forward converter. This paper presents analysis, design and experimental verification of a two-switch forward converter. First, the converter operation is analyzed, enabling its key equations and important waveforms to be established. Then, the converter design, including both the power circuit and feedback controller, is illustrated in detail. Finally, experimental results from the prototype circuit are presented to confirm the validity of the analysis and design.

Control and Analysis of Magnetic Switch Reset Current in Pulsed Power Systems

This letter presents the operation characteristics of the magnetic switch attributed to the input voltage and pulse frequency in the pulsed power system. The reset current control method is proposed for improving efficiency of the magnetic switch because this method will optimally controls the hysteresis loop of the magnetic switch. Also, this method controls the saturation of the magnetic core by adjusting the amount of reset current flowing in the magnetic switch when the input voltage and pulse frequency at the pulsed power system are changed. Experimental results are presented to demonstrate the effectiveness of the proposed reset current control method of the magnetic switch.

Modeling, analysis, and design criteria of actively clamped double-ended converters

The characteristics of actively clamped double-ended (ACDE) converters are studied. It is found that they possess interesting features such as near-zero output current ripple and require no magnetic reset winding. A low-frequency behavior model of the ACDE converter is derived, from which important relationships among output voltage V/sub 0/, input voltage V/sub i/, and duty cycle D are obtained. When compared with other forward-derived converters, an ACDE converter has extra poles and zeros in the small-signal control-to-output and input-to-output transfer functions. The design criteria and experimental results are also reported.

4837552 Non-volatile fault display with magnetic reset switch for adaptive braking system

A fault indicating mechanism for an electronic system, such as a vehicle adaptive braking system, includes a series of visual indicators, such as light emitting diodes, on one surface of the housing within which the electronic components comprising the system are sealed. Each of the indicators is activated in response to a predetermined malfunction sensed in the system, such as a defective speed sensor, defective modulator, or a defect in the electronic circuitry. A magnetically responsive switch is sealed within the housing adjacent the indicators, but is not visible from the exterior of the housing. The indicators are reset when the system is repaired by the mechanic who holds a common magnet against the housing adjacent the switch. When the switch is activated by a magnet, all of the indicators flash on and are then turned off. A non-volatile RAM stores malfunctions sensed by the system when the system is powered down, so that all malfunctions are again indicated immediately when the system is powered up.