A Square-Wave Current Inverter for Aircraft-Mounted Electromagnetic Surveying Systems

Abstract.A bipolar triangular wave current pulse inverter for shallow TEM survey is described. It can generate a peak current more than 10A and the PRF of the bipolar current pulse is between 1Hz and 10kHz. The proposed inverter contains a high voltage source circuit for the rising edge and a Zener diodes circuit with constant voltage clamping for the falling edge. Measurement results are presented, which show the high quality triangular wave current pulse with linear rising edge and rapidly turnoff falling edge.

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“…The derivative of the rising stage and the falling stage can be obtained by formula (8) and formula (9) d…”

Section: �1�mentioning

confidence: 99%

“…Due to stray parameters [8] of the entire system, there is a high frequency oscillation at the early part of the turnoff current when the switch is suddenly cut off. The oscillation will affect the early electromagnetic data, so a RCD circuit parallel to each MOSFET is added to absorb and decrease the oscillation current [9].…”

Section: Inverter Circuitmentioning

confidence: 99%

Bipolar Triangular Wave Current Pulse Inverter for Shallow TEM Survey

et al. 2018

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“…This approach typically uses a high-voltage bulk capacitor to clamp the falling edge of the pulse current [9]. For instance, rapid turn-off of the pulse current was achieved through the resonance of the high-voltage capacitor with the transmitting coil [10]. However, this method yields the falling edge of the pulse current similar to the sinusoidal waveform, resulting in a larger nonlinear error.…”

Section: Introductionmentioning

confidence: 99%

“…Consequently, for the inverter circuit equipped with a damping resistor or RC snubber, the current continues to flow through the damping resistor or RC snubber circuit, resulting in exponential decay [12][13][14][15]. For the circuit without a damping resistor or RC snubber, the current oscillates via the coil's parasitic capacitance and internal resistance [9][10][11]. We defined the current during this time as the tail current (TC).…”

Section: Introductionmentioning

confidence: 99%

Influence of Parasitic Capacitance on Turn-Off Current and Its Optimization Method for Transient Electromagnetic System

Liao,

Xu,

Liu

et al. 2024

IEEE Trans. Instrum. Meas.

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In transient electromagnetic (TEM) inverter circuits, a damping resistor is typically connected in parallel to the transmitting coil to prevent overshoot during the turn-off period of the pulse current. This configuration results in an exponential decay waveform for the pulse current, which prolongs the turn-off time and increases the nonlinear error. This paper analyzes the impact of the parasitic capacitance on the value of the damping resistor and the end-period waveform of the pulse current base on the inverter circuits, and proposes an optimized control method to reduce both the turn-off time and the nonlinear error of the pulse current. The method is validated through the construction of an experimental circuit. According to the experimental data, this optimization method reduces the turn-off time by 23.8% and the nonlinear error by 5.5%. In the unexploded ordnance (UXO) detection experiment, the optimization method's detection results exhibit higher resolution.

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Bipolar square-wave current source for transient electromagnetic systems based on constant shutdown time

Wang

Yin

Lin

et al. 2016

Review of Scientific Instruments

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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.

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A Square-Wave Current Inverter for Aircraft-Mounted Electromagnetic Surveying Systems

Cited by 11 publications

References 3 publications

Bipolar Triangular Wave Current Pulse Inverter for Shallow TEM Survey

Bipolar Triangular Wave Current Pulse Inverter for Shallow TEM Survey

Influence of Parasitic Capacitance on Turn-Off Current and Its Optimization Method for Transient Electromagnetic System

Bipolar square-wave current source for transient electromagnetic systems based on constant shutdown time

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