Pulse Width Modulation-Based Voltage Stabilization System and Control Method for Downhole Generators

The downhole generator is a key source of electrical energy for the guided drilling system. When a turbine is used as the prime mover of the generator, the traditional voltage stabilizing system faces problems such as a wide range of bus voltage fluctuations and high peak voltages due to the variation in the drilling fluid flow rate that drives the turbine. In the complex and changeable downhole operating environment, the requirements for the stability and reliability of the electrical system are becoming increasingly strict. Traditional voltage stabilizing technologies can no longer meet the demands of modern downhole operations for high-precision and high-reliability power supply. This paper designs a downhole damping generator voltage stabilizing system based on pulse width modulation (PWM) technology and proposes a multi-mode collaborative precise regulation PWM voltage stabilizing control strategy. The hardware circuit adopts an LC low-pass filter to remove high-frequency noise and selects high-voltage power amplifiers and high-current MOSFETs to meet the requirements of power amplification in complex downhole conditions. The aim is to solve the problem of excessive voltage fluctuations in the output of the downhole generator and improve the stability of the output voltage. By building a voltage stabilizing function test platform covering core components such as the generator, voltage stabilizing circuit, and control unit, the effectiveness of the scheme was verified. The test results show that under composite interference conditions such as temperatures ranging from 80 to 125 ℃ and fluctuating loads from 100 to 2000 W, the system can stabilize the voltage at 450 V, with voltage fluctuations controlled within ± 2.5%, and the transient response time reduced to less than 50 ms. This significantly improves the stability of the downhole generator’s power supply and provides reliable power support for the guiding tools.