Emission Coil Driving Subsystem for Crosswell Electromagnetic Logging Tools

A kind of driving system is designed for the large excitation current and inductance. The H bridge circuit is used in system to form a power inverter, and the unipolar doubling SPWM modulation is selected as the inverter control mode. Measuring the impedance characteristics of the emission coil, when the transmission frequency is less than 100Hz, the filtered sine wave is used to drive the transmission coil, and the series resonant emission mode is selected when the transmission frequency is more than 100Hz. The experimental results show that the emission current can reach about 1A at the low frequency and resonant frequency.