Zhong Heqing

Design and Construction of a Trigger Generator Based on Pulse Transformer for Spark Gap Switch

A two-electrode graphite spark gap switch is used as the main discharge switch and triggered by a reliable trigger generator in a pulsed-power conditioning system. The trigger generator based on resonant charging of a pulse transformer is constructed. An appropriate ratio can be obtained when using resonant charging based on a core-type pulse transformer. The charging time is dependent on the leakage inductance and the capacitance of the primary and secondary capacitors. The stray resistance and magnetizing inductance of the resonant charging circuit have an impact on ratio and energy transmission efficiency. A dry-type pulse transformer with a load of 1.08 nF, an output voltage of more than 130 kV, and a winding ratio of 65 is presented. A self-breakdown three-electrode output switch is used to shorten the rise time of the output impulse. The deviation of the self-breakdown voltage of the self-breakdown three-electrode output switch is much smaller than that of the self-breakdown two-electrode output switch. It assures that the trigger generator has a low jitter of output impulse when a lot of energy modules work simultaneously. The output impulse of the trigger generator with a peak value of more than 120 kV and a rise time of less than 30 ns can trigger the two-electrode graphite spark gap switch reliably.

Research on resonant parameters design method of series-parallel resonant capacitor charging power supply

In pulsed power system, capacitor charging power supplies (CCPS) are normally employed to provide energy for capacitor. To meet the request of reducing input power rate, this paper focuses on the series-parallel resonant CCPS. In this paper, the electric characteristic of series-parallel resonant converters is analyzed in detail. Based on theoretical analysis, the resonant parameters design method of series-parallel resonant converters, which contains resonant parameters design and pulse width of drive signal design, was proposed. Simulation verifications and experimental results are carried out to prove the validity of theoretical analysis.

A Study of Dual-loop Control Scheme and Corresponding Neutral-point Voltage Balance Control Method for Three-level PWM Rectifiers

The mathematical model of the three-level PWM rectifiers is set up in this paper. By comparing it with the model of DC motors, some similarities are established. Based on the state feedback decoupling, the dual-loop close control scheme of DC motors is implemented to three-level PWM rectifiers. As a result, the three-level rectifier has favorable dynamic and steady state performance, sinusoidal input current and unity power factor. Besides, a method is proposed to control the neutral-point voltage charge unbalance, which is an inherent problem of three-level inverter. The redundant positive switching states or negative switching states of small vectors are selected according to the direction information of input current of each phase as well as the ripple of neutral-point voltage. Finally, experimental results verify the feasibility and validity of dual-loop control scheme and neutral-point (NP) voltage balancing control method.

A DTC Algorithm for Three-level Induction Motor Drives System Based on Discrete Space Vector Modulation

In this paper, an uniform mathematic model of three-level inverters feed induction motor drives system has been constructed. Based on the application of the discrete space vector modulation (DSVM), a DTC strategy of three-level inverters induction motor drives system is proposed. With DSVM-DTC algorithm, the neutral-point (NP) voltage balancing problem and high dv/dt of output voltage is restrained. The proposed algorithm does not deteriorate dynamic performance of traditional DTC schemes, and does not increase switching loss at the same time. The experimental results verify the correctness and feasibility of the proposed control scheme.