Research and Implementation on Low-frequency Sine Wave Current Source for Testing

In order to meet the requirements of the testing excitation source,a low-frequency sine wave current source is designed and realized.The proposed current source consists of a pre-regulation switching voltage source,a switching DC voltage source,a linear DC sine wave current source,an H-bridge and an intelligent controller.The H-bridge can convert the polarity.The linear DC sine wave current source is used to improve the quality of the sine current and the dynamic behavior.The switching DC voltage source is the middle stage,which can reduce the voltage on the regulating transistor and improve the efficiency.The pre-regulation switching voltage source is the input stage,which can regulate the input voltage to a suitable value.LPC2138 is used as the intelligent controller of the whole system.The experiment results show that the proposed current source is feasible,and has the advantages of stable output current,low THD,wide frequency range and small frequency step.