title: Bipolar square-wave current source for transient electromagnetic systems based on constant shutdown time.
abstract: Cooperative work of multiple magnetic transmitting sources is a new trend in the development of transient electromagnetic system. The key is the bipolar current waves shutdown, concurrently in the inductive load. In the past, it was difficult to use the constant clamping voltage technique to realize the synchronized shutdown of currents with different peak values. Based on clamping voltage technique, we introduce a new controlling method with constant shutdown time. We use the rising time to control shutdown time and use low voltage power source to control peak current. From the viewpoint of the circuit energy loss, by taking the high-voltage capacitor bypass resistance and the capacitor of the passive snubber circuit into account, we establish the relationship between the rising time and the shutdown time. Since the switch is not ideal, we propose a new method to test the shutdown time by the low voltage, the high voltage and the peak current. Experimental results show that adjustment of the current rising time can precisely control the value of the clamp voltage. When the rising time is fixed, the shutdown time is unchanged. The error for shutdown time deduced from the energy consumption is less than 6%. The new controlling method on current shutdown proposed in this paper can be used in the cooperative work of borehole and ground transmitting system.
authors.affiliation: College of Instrumentation and Electrical Engineering, Jilin University, Changchun 130026, China.
authors.forename: Shilong
authors.initials: S
authors.lastname: Wang
authors.affiliation: College of Geo-exploration Science and Technology, Jilin University, Changchun 130026, China.
authors.forename: Changchun
authors.initials: C
authors.lastname: Yin
authors.affiliation: College of Instrumentation and Electrical Engineering, Jilin University, Changchun 130026, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Lin
authors.affiliation: College of Instrumentation and Electrical Engineering, Jilin University, Changchun 130026, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Yang
authors.affiliation: College of Instrumentation and Electrical Engineering, Jilin University, Changchun 130026, China.
authors.forename: Xueyan
authors.initials: X
authors.lastname: Hu