A Second-Order Fast Discharge Circuit for Transient Electromagnetic Transmitter

Area of Science:

• Electrical Engineering
• Electromagnetics
• Power Electronics

Background:

• Transient Electromagnetic (TEM) transmitters often face challenges with long turn-off times, particularly with inductive loads.
• This limitation can impact the efficiency and performance of TEM systems.

Purpose of the Study:

• To introduce and analyze a novel second-order fast discharge circuit topology for TEM transmitters.
• To address and mitigate the issue of prolonged turn-off durations in TEM transmitters.

Main Methods:

• A new second-order circuit topology was integrated into the standard H-bridge structure, incorporating a capacitor, two Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs), and two resistors.
• The operating principles of the four stages were analyzed, and mathematical models for turn-off time and MOSFET voltage stress were developed.
• Resistor and capacitor parameters were optimized for a fixed transmitter coil.

Main Results:

• The proposed topology demonstrated a current-independent turn-off time, achieving the shortest duration at 50 A compared to other topologies.
• Lower voltage stress on the MOSFET was observed at 9 A.
• Experimental results confirmed a consistent turn-off time of approximately 64 μs across various current loads (1 A, 5 A, 9 A).
• RLC series resonance further reduced the turn-off time to 58 μs, maintaining load-current independence.

Conclusions:

• The novel second-order fast discharge circuit effectively reduces MOSFET turn-off times in TEM transmitters.
• The circuit's performance is characterized by a load-current-independent turn-off duration and reduced voltage stress.
• This advancement offers a significant improvement for TEM transmitter design and application.