Jianfeng Xie

Design of Multipulse Power Supply for Small Pulsed High Magnetic Field Device

Three small pulsed high magnet field devices (SPHMF) which can continuously operate 20 times in rated power with different maximum magnetic field intensity from 10 T~40 T were developed in Wuhan High Magnet Field Center(WHMFC). The SPHMF systems are used to investigate the sterilization of fruit juice, magnetization of permanent magnet for wind power generator, some industrial applications and so on. The SPHMF consists of pulsed capacitor power supply, charger, control & measurement system, cryogenic system and pulsed magnet. These systems can accommodate sample room size from ¿12 mm to ¿18 mm and hold sample room in indoor temperature 300 K for different scientific researches and high magnetic field industrial applications. In this paper, power supply, magnet, control system and cryogenic system are presented. The total experiment results of SPHMF show that the devices are feasible, steady and reliable.

Precise Measurement of the Inductance and Resistance of a Pulsed Field Magnet Based on Digital Lock-in Technique

In order to guarantee the safe operating conditions of pulsed field magnets and anticipate impending catastrophic failure, the precise measurement of inductance and resistance of the magnet is most useful. A measurement system based on the Digital Lock-In (DLI) technique has been developed. A non-inductive reference resistor with high thermal stability is connected with the magnet in series. Two reference signals are generated virtually. The voltages across the reference resistor and the magnet are used as measurement signals which are sampled synchronously by the Analog-to-Digital Converter (ADC) and processed with a DLI amplifier algorithm. The inductance and resistance of the magnet can then be derived by computation. The Infinite Impulse Response (IIR) filter design, measurement system implementation and error analysis are described. The accuracy of the inductance measurement is better than 0.01% in practice. The measurement system has been implemented at the Wuhan National High Magnetic Field Center (WHMFC) with excellent performance.

Design of a Program-Controlled Precise Synchronous Triggering System Applied to Pulsed High Magnetic Field Facility

Recently, a Program-controlled Synchronous Triggering System (PSTS) is developed at Wuhan National High Magnetic Field Center. The designed system could generate triggering signal for thirteen power modules and eight magnets distributed in different experiment stations. By generating precise and synchronous triggering signals required for the facility, the multiple power modules could be discharged synchronously or in a preset time sequence. The PSTS is composed of triggering signal generator, fiber converter, expanded cell, and local sequence generator. The triggering signal generator, isolated from local device, is applied for sequential control of multi-module in the facility. The signal transmission is realized by optical fiber. A Digital Signal Processor (DSP) with specific type of TMS320F2812 is employed to design the triggering signal generator. The parameters of triggering channels and time-delay with the accuracy of 1 us could be configured through human machine interface. Local sequence generator unit is integrated in the local control unit on the basis of a Complex Programmable Logic Device (CPLD) with specific type of EPM7128. Local sequence generator is responsible for producing the time sequence signals to control and record the waveform of each power module, as well as the triggering signal waveform modulation for thyristor through expanded cell. Based on the designed system, the pulsed high magnetic field facility could be operated effectively. The test result illustrates that the system is of high performance.

A Software Approach for Real-Time Control of Operation and Experiments at the WHMFC Pulsed High Magnetic Field Facility

A newly developed Control Software System (CSS) designed to control and monitor the operation of the magnets and the experiments at the Wuhan High Magnetic Field Center (WHMFC) pulsed high magnetic field facility is described. The CSS implements the functions of status evaluation and experiment process control in real time as well as the functions of system structure configuration and data management off-line. Using software architecture based on component-oriented technology, scenarios about control flow rebuilding, interfacing with local control hardware, synchronous triggering and transfer of the results of measurements are discussed in detail. Hardware simulator design and human machine interface of the CSS are described as well. The test results show that the entire operation process is perfectly handled by the CSS which provides an integrated platform for scientific experiments and research.

The Simulations and Experiments of the Electromagnetic Tracking System Based on Magnetic Dipole Model

Electromagnetic tracking devices, which determine the location and orientation of objects, are widely used in bio-medicine, virtual reality, and so on. Based on the magnetic dipole model, a three-dimensional electromagnetic tracking system is discussed in the paper. The experimental system is composed of emitting coils, receiving coil, and a data acquisition instrument. The theoretical deviations are analyzed through formula derivation and model simulations, which is about magnetic induction intensity and induced electromotive force. The digital lock-in technique is utilized to pick up the weak signal of induced electromotive force of the receiving coil from the environmental noise. The Gauss-Newton and Genetic algorithms are taken to solve the nonlinear equations for the position and orientation of the receiving coil. The experiments show that the discussed system is feasible and effective.

Development of an Optical Digitized Local Control and Measurement System Applied to Pulsed High Magnetic Field Facility

A reliable controlling and measuring system in a pulsed high magnetic field facility is important for efficient operation. To control and monitor the status of switches, relays and thyristors, an optical digitized local controlling and measuring system (LCMS) was applied in Wuhan High Magnetic Field. On the basis of a digital signal processor (DSP) with specific type of TMS320F2812, LCMS receives and executes the commands including setting parameters, charging, dumping and discharging issued from the Human-Machine Interface (HMI) at the control room. Meanwhile, a fiber optic transmission system is needed to provide galvanic isolation. The discharge current and voltage of capacitor bank are measured by Rogowski coil and resistance divider respectively. The whole system test shows that the designed system is effective and reliable.

Function Design and Implementation of a Central Control System of a Pulsed High Magnetic Field Facility

A user-friendly Central Control System (CCS) for the pulsed high magnetic field facility has been designed and implemented at the Wuhan National High Magnetic Field Center (WHMFC). The CCS is composed of the server, the Human Machine Interface (HMI) and the configuration tool. The controlled objects and functions of the CCS are introduced first, and then the design and implementation of key functions are given. The CCS is developed on basis of a client/server mode, so multiple users can use the system simultaneously. To achieve higher pulsed magnetic fields, a synchronous trigger sequence is used, which can trigger up to 13 power modules to be discharged into a magnet with multiple coils. Benefiting from component technology and the TCP/IP communication protocol, the CCS can monitor signals in real time and receive experimental data from recording devices running on different platforms. The test results show that the CCS meets the requirements of experiments and simplifies the control operation.

The development of measurement and control software applied to small pulsed high magnetic field facility

In order to satisfy the research demand of the small pulsed high magnetic field facility, an implementation of the software for the control system of pulsed high magnetic field facility is presented in this paper. The system is based on VC and Measurement Studio Platform, and the communication mechanism of finite state machine is applied in it. The state of the hardware circuit is monitored by the system and the trig action of charging and firing according to the parameters set by user is controlled by it too. Two control modes are provided: manual mode and auto mode. The signal of time rate of change of magnetic field is sampled and its integration signal is calculated too. The result of experiments shows that this system reaches the designed purpose.

Analysis and Design of a Control System for the 100 T Pulsed High Magnetic Field Facility at WHMFC

A pulsed high magnetic field of 90.6 T has been achieved by discharging the energy in a capacitor bank to a nondestructive magnet at Wuhan National High Magnetic Field Center (WHMFC), and recently, the project for a 100-T magnetic field has been under development. The pulsed magnet with a 100-T magnetic field will be composed of three coils, which are driven by three types of power sources. Based on the existing control subsystems of these power sources, the design of the control system that can control different types of power supplies to discharge would be taken into consideration for the implementation of the 100-T magnetic field. This paper first analyzes the control process for the 100-T system, which can divided into three stages, and the time requirement for each stage. Based on the analysis, the structure and main functions of the control system are discussed, and then the main control program and the global control block are designed. To protect the safety of the system, some protection measures are finally discussed. This paper provides design bases for the realization of the control system.

Design of the power supply for the pulsed electric current sintering

The pulsed electric current sintering (PECS) is a new rapid sintering technique. As an important part of the PECS system, the pulsed electric current power supply is one of the main factors which affect the sintering result. This paper proposes a pulsed electric current power supply topology based on phase-shift full-bridge converter, which implements ZVS (zero voltage switching). By controlling the PWM output, it implements such variety output modes as pulse mode, DC mode and Pulse-DC mode. The power supply can output 700A current and 14V voltage. Its output pulse width is a minimum of 2ms, and can be adjusted by the user.