The magamp (magnetic amplifier) is widely used in power supplies due to its low cost, simplicity and other advan-tages. This paper discusses a novel application of the magamp in switching power supplies, where the mag...The magamp (magnetic amplifier) is widely used in power supplies due to its low cost, simplicity and other advan-tages. This paper discusses a novel application of the magamp in switching power supplies, where the magamp is used to regulate pulse width modulation (PWM) instead of power signal in the main circuit. This method extends the application of the magamp in power supplies, and makes it possible to further regulate control signal when PWMs have been generated. Based on this applica-tion, a new current-sharing (CS) scheme using the magamp is proposed, which uses a modified inner loop CS structure. In this scheme PWMs are generated by one main controller, and CS is achieved by regulating PWMs using a magamp in each module. Compared with traditional application of the magamp, the new CS scheme can be used in most topologies and only requires magamps of low power capacity. Then a test circuit of parallel power supply is developed, in which CS is achieved by a PWM regulator with the magamp. The proposed scheme is also used to upgrade an electroplate power to make it capable of paralleling supplies. Experimental results show that the proposed scheme has good CS performance.展开更多
In view of the low resolution and accuracy of traditional magnetometer,a method of microwave frequency modulation technology based on nitrogen-vacancy(NV)center in diamond for magnetic detection was proposed.The magne...In view of the low resolution and accuracy of traditional magnetometer,a method of microwave frequency modulation technology based on nitrogen-vacancy(NV)center in diamond for magnetic detection was proposed.The magnetometer studied can reduce the frequency noise of system and improve the magnetic sensitivity by microwave frequency modulation.Firstly,ESR spectra by sweeping the microwave frequency was obtained.Further,the microwave frequency modulated was gained through the mixed high-frequency sinusoidal modulation signal generated by signal generator.In addition,the frequency through the lock-in amplifier was locked,and the signal which was proportional to the first derivative of the spectrum was obtained.The experimental results show that the sensitivity of magnetic field detection can reach 17.628 nT/Hz based on microwave frequency modulation technology.The method realizes high resolution and sensitivity for magnetic field detection.展开更多
Soft magnetic composite with micro-cellular structure was prepared by spark plasma sintering(SPS) process with Fe73.5Cu1Nb3Si13.5B9 micron-powders clad by 5wt% Zn0.5Ni0.5Fe2O4 nano-particles.The effect of SPS on the m...Soft magnetic composite with micro-cellular structure was prepared by spark plasma sintering(SPS) process with Fe73.5Cu1Nb3Si13.5B9 micron-powders clad by 5wt% Zn0.5Ni0.5Fe2O4 nano-particles.The effect of SPS on the micro structure of the Finemet powder and the micro structure of the composite were studied.It has been found that the as-prepared composite consists of Fe73.5Cu1Nb3Si13.5B9 cells and the cell-wall composed of nano Zn0.5Ni0.5Fe2O4 particles distributing around Fe73.5Cu1Nb3Si13.5B9 cell-body.The composite exhibits low eddy-current loss which is to be resulted by high resistivity of the Zn0.5Ni0.5Fe2O4 cell-wall.The sintered samples were annealed at different temperature and the magnetic properties at different frequency of the annealed samples were measured.It shows that the Zn0.5Ni0.5Fe2O4 cell-wall possesses good thermostability.展开更多
基金Project (No. 50677063) supported by the National Natural Science Foundation of China
文摘The magamp (magnetic amplifier) is widely used in power supplies due to its low cost, simplicity and other advan-tages. This paper discusses a novel application of the magamp in switching power supplies, where the magamp is used to regulate pulse width modulation (PWM) instead of power signal in the main circuit. This method extends the application of the magamp in power supplies, and makes it possible to further regulate control signal when PWMs have been generated. Based on this applica-tion, a new current-sharing (CS) scheme using the magamp is proposed, which uses a modified inner loop CS structure. In this scheme PWMs are generated by one main controller, and CS is achieved by regulating PWMs using a magamp in each module. Compared with traditional application of the magamp, the new CS scheme can be used in most topologies and only requires magamps of low power capacity. Then a test circuit of parallel power supply is developed, in which CS is achieved by a PWM regulator with the magamp. The proposed scheme is also used to upgrade an electroplate power to make it capable of paralleling supplies. Experimental results show that the proposed scheme has good CS performance.
基金National Natural Science Foundation of China(Nos.51635011,61503346,51727808)National Science Foundation of Shanxi Province(No.201701D121080)
文摘In view of the low resolution and accuracy of traditional magnetometer,a method of microwave frequency modulation technology based on nitrogen-vacancy(NV)center in diamond for magnetic detection was proposed.The magnetometer studied can reduce the frequency noise of system and improve the magnetic sensitivity by microwave frequency modulation.Firstly,ESR spectra by sweeping the microwave frequency was obtained.Further,the microwave frequency modulated was gained through the mixed high-frequency sinusoidal modulation signal generated by signal generator.In addition,the frequency through the lock-in amplifier was locked,and the signal which was proportional to the first derivative of the spectrum was obtained.The experimental results show that the sensitivity of magnetic field detection can reach 17.628 nT/Hz based on microwave frequency modulation technology.The method realizes high resolution and sensitivity for magnetic field detection.
基金supported by the National Natural Science Foundations of China (Grant Nos. 50771023 and 51071034)
文摘Soft magnetic composite with micro-cellular structure was prepared by spark plasma sintering(SPS) process with Fe73.5Cu1Nb3Si13.5B9 micron-powders clad by 5wt% Zn0.5Ni0.5Fe2O4 nano-particles.The effect of SPS on the micro structure of the Finemet powder and the micro structure of the composite were studied.It has been found that the as-prepared composite consists of Fe73.5Cu1Nb3Si13.5B9 cells and the cell-wall composed of nano Zn0.5Ni0.5Fe2O4 particles distributing around Fe73.5Cu1Nb3Si13.5B9 cell-body.The composite exhibits low eddy-current loss which is to be resulted by high resistivity of the Zn0.5Ni0.5Fe2O4 cell-wall.The sintered samples were annealed at different temperature and the magnetic properties at different frequency of the annealed samples were measured.It shows that the Zn0.5Ni0.5Fe2O4 cell-wall possesses good thermostability.
