US 12,013,417 B2
Closed loop current transformer
Xiaoming Fan, Guangdong (CN)
Assigned to SHENZHEN ZHIYONG ELECTRONICS CO., LTD., Shenzhen (CN)
Appl. No. 17/640,855
Filed by SHENZHEN ZHIYONG ELECTRONICS CO., LTD., Guangdong (CN)
PCT Filed Apr. 24, 2020, PCT No. PCT/CN2020/086667
§ 371(c)(1), (2) Date Mar. 7, 2022,
PCT Pub. No. WO2021/208135, PCT Pub. Date Oct. 21, 2021.
Claims priority of application No. 202010286058.2 (CN), filed on Apr. 13, 2020.
Prior Publication US 2022/0334146 A1, Oct. 20, 2022
Int. Cl. G01R 15/18 (2006.01); G01R 15/20 (2006.01); G01R 19/00 (2006.01); H03F 3/20 (2006.01)
CPC G01R 15/181 (2013.01) [G01R 15/202 (2013.01); G01R 19/0092 (2013.01); H03F 3/20 (2013.01)] 12 Claims
OG exemplary drawing
 
1. A closed loop current transformer, characterized in that, comprising a magnetic ring, a hall element, a power amplifier circuit, a first compensating coil, a second compensating coil and a signal detection circuit;
the magnetic ring is an annular permeable magnetic cylinder with a notch;
the hall element is positioned in the notch of the magnetic ring and used for generating an induced voltage according to a primary magnetic field generated in the magnetic ring by a current to be measured;
the first compensating coil and the second compensating coil are both multi-turn coil, and wound on opposite sides of the magnetic ring in a same winding direction;
an input end of the power amplifier circuit is connected with an output end of the hall element, and an output end of the power amplifier circuit is connected with a first end of the first compensating coil and a first end of the second compensating coil respectively;
a second end of the first compensating coil is connected with a first input end of the signal detection circuit, and a second end of the second compensating coil is connected with a second input end of the signal detection circuit, an output end of the signal detection circuit is used as an output end of the closed loop current transformer; and
when a wire to be measured passes through the magnetic ring and flows through the current to be measured, a primary magnetic field is generated in the magnetic ring, and the hall element is used to generate the induced voltage according to the primary magnetic field; and the power amplifier circuit is used for synchronously utilizing positive and negative power supplies to output the first compensating current and the second compensating current which are opposite to each other according to the induced voltage, the first compensating current is used to drive the first compensating coil, and the second compensating current is used to drive the second compensating coil, so that the first compensating coil and the second compensating coil generate a superposable magnetic field; the signal detection circuit is used for detecting the first compensating current and the second compensating current and outputting a voltage measurement value according to the first compensating current and the second compensating current; when a compensating magnetic field generated by the first compensating coil and the second compensating coil are superimposed to just counteract the primary magnetic field generated by the current to be measured, the voltage measurement value output by the signal detection circuit is proportional to the current to be measured.