| At present,many areas are facing severe water quality,seasonal water shortage and regional water shortage.NMR water search is the most comprehensive,effective and economical water search technology.Unlike the previous detection technology,it is currently the only non-invasive water detection method.The nuclear magnetic resonance water detector using nuclear magnetic resonance technology is the most advanced equipment with the most complete functions and the most measured parameters.It is flexible and convenient,and integrates receiving and transmitting.As an important part of the nuclear magnetic instrument,the power supply device not only provides the energy required for transmitting the excitation pulse to the transmitting device of the instrument,but also provides the electrical energy required for other devices to work.The traditional power supply device has many design defects,such as scattered structure,large size,difficult coordination,slow charging speed,low voltage detection accuracy,poor stability and reliability,hidden safety,and easy to cause EMI to the received signal.In response to the above problems,a new version of the power supply device is designed.The power supply device of this design is mainly composed of three parts: a 24 V lead-acid battery,a DC / DC switching power supply and an energy storage capacitor.Among them,the full-bridge inverter circuit and full-bridge high-voltage rectifier circuit are used as the main structure of the DC / DC conversion circuit.The PMOS switch circuit controls the opening and closing of the DC / DC conversion circuit.The constant current discharge circuit is designed to make the energy in the storage capacitor to the constant current mode is released,and a filter capacitor fast discharge circuit is added;the PWM control technology is used to control the 24 V lead-acid battery to charge the storage capacitor constant current,and also control the charging voltage;the voltage detection circuit and temperature measurement circuit are designed to Real-time monitoring of 24 V lead-acid battery voltage,storage capacitor voltage,and upper tank temperature;interface circuit controls and protects the access of 24 V lead-acid battery voltage,while designing multiple power modules to provide working voltage for other circuits;through MCU + CPLD the control circuit is formed to control the coordinated work of all parts of the entire power supply device,and establishes a network connection with the host computer through 485 communication to achieve the control of the power supply device by the host computer;on this basis,a parallel charging technology with a master and n slaves is applied,can greatly increase the charging current,thereby shortening the charging time.Indoor and outdoor software and hardware tests were performed on each part of the circuit of the power supply device.The results show that the output voltage is 0-450V(adjustable),the charging current is an integer multiple of 1.75 ± 0.05 A,and the charging efficiency is not less than 75%.The discharge current of the energy storage capacitor is always 200 ± 10 mA,the discharge time of the filter capacitor does not exceed 100 ms,and the measurement accuracy of high voltage and low voltage is not higher than 1%.It can realize two kinds of charging control of the manual switch and the front panel of the host computer.Three kinds of discharge control of program-controlled discharge and automatic discharge after shutdown,over-voltage,overcurrent and over-heat protection functions,and remote 485 communication control of 20-30 m.Each part of the circuit can meet the technical parameters required by the design,and can work in coordination with other devices,so that the nuclear magnetic resonance water detector can detect the nuclear magnetic signal,and the nuclear magnetic resonance water detector can be accurate,small,fast,good and high for the power supply device.Design requirements,with good engineering applications. |
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