A Non-contact Solenoid Valve Control System For Downhole Applications

Non-contact coupling technique has been regarded as a new way for energy transmission. Senders and receivers can be separated and energy is transmitted by magnetic coupling, which means no mechanical or electrical connection is needed. Based on these advantages, it can be applied to the oil well, underwater and other occasions which the sender and receiver are not suitable for direct connection, and thus can improve the security of the systems. Nowadays, power transmission between the ground and the underground system mainly use cables. In terms of the oil well, this mode needs electrical equipment connected by cables directly, which may produce sparks. While oil is the flammable, it is easy to cause an explosion. Therefore, the emergence of non-contact coupled transmission provides a new idea to solve this problem.In this article, a non-contact solenoid valve control system is proposed. The system consists of three components, namely electric power transmission unit, signal transmission unit and solenoid valve control unit. The non-contact power transmission unit is used to supply power for the solenoid valve. When the system on the ground wants to control the valve in the well, the non-contact signal transmission unit will send the commands to the circuit in the well, then the circuit decides whether the power transmission unit connects the valve, which controls the valve to be on or off. In fact, the power transmission unit is based on high-frequency inverter technology, while the signal transmission unit is based on FSK modulation and demodulation.A simulation system for non-contact solenoid valve control is established initially, including a shifting component, a primary coupler and a secondary coupler. Then some circuits to transmit power and signal and to control the valve are developed. Finally, the system can provide at least 50 W of power to the solenoid valve when the distance between primary and secondary is in the range of 85 mm, and provide at least 100 W of power when it is in the range of 43 mm. Moreover, it achieves to control the valve.