| With the rapid development of economy,the contradiction between the strong demand for mineral resources and the insufficient domestic supply has become increasingly prominent.The ocean is rich in oil and gas resources,so it is urgent to explore and develop it.In the marine electromagnetic exploration,the marine electromagnetic detection method is the main means of marine oil and gas resource exploration,and the marine controlled source electromagnetic transmitter is the key equipment for the controlled source electromagnetic exploration.At present,the controlled source circuit of the marine electromagnetic transmitter is a unidirectional flow of electric energy.When the emission dipole releases the stored energy,the energy cannot be fed back,causing the DC bus voltage to rise,the voltage stress of the switch devices to increase,and even the filter capacitor and switch devices are burned,which cannot guarantee the long-term reliable operation of the underwater devices body in the deep sea.In this paper,a bidirectional active full-bridge DC-DC converter is introduced as the controlled source circuit of the marine transmitter,the hybrid control strategy based on current stress optimization and sliding mode control is designed,and the control variables are decoupled.The main research contents are as follows:Firstly,the operating principle of the marine electromagnetic transmitter is introduced in detail,and then the topology of the bidirectional controlled source circuit is presented,and the transmission power and the realization of soft-switching are deduced by using the extended phase-shift control.Aiming at the problem that the loss increases due to the large inductance current in the phase-shifting control of the bidirectional controlled source circuit,the generation mechanism of the peak inductance current is analyzed.The inductor current stress optimization control is adopted to ensure a steady-state operation;In the transient state,the sliding mode variable structure control method is adopted,and the univariate extended phase-shifting sliding mode control is adopted to realize the fast energy feedback in the inductive load.The simulation results show that the current stress optimization and the sliding mode control are seamlessly connected through the hysteresis loop,which reduces the peak value of the inductor current and the DC bus voltage and realizes the bidirectional flow of energy in the control system.Secondly,aiming at the oscillation of transformer primary inductance current caused through hybrid control,a bivariate decoupling control strategy is proposed.The original coupled nonlinear system is globally linearized into two single input single output systems.Based on the model established in the front and rear stages of the transformer,taking the bus voltage and inductive current as the system error,the controller with sliding mode surface and reaching law is established,which meets the requirements of sliding mode design,and the functional relationship of sliding mode controller is obtained.The simulation results show that the decoupling control strategy realizes the complete decoupling between the control variables,the peak value of inductance current and DC bus voltage is further optimized,and the control system has good robustness and dynamic performance.Finally,a 600 W bidirectional controlled source circuit experimental prototype based on Infineon XMC4500 control was built,and the hardware design of the power circuit,control circuit,drive circuit and sampling circuit was carried out.The experimental results show that the designed bidirectional controlled source circuit can quickly feed back the energy stored in the emission dipole,and at the same time reduce the current stress,which lays a foundation for the development of high-power marine electromagnetic controlled source transmitters. |
