The Research on Switch-Linear Hybrid of Precise Current Source

In this paper, a novel current control strategy of precise current source is presented, which combines switch power conversion mode with linear amplification mode. The linear power amplifier is used as the power converter in the current loop. The current controller is a double cascaded PI (DCPI) controller which is put up by the way of analog circuit, it can suppress the high frequency disturbance signal effectively. The switch-filter circuit can generate a special power supply for linear power amplifier, the voltage of this special power supply changes as the load voltage does. The topology of four-level H-Bridge works as the power converter of the switch power amplifier, the LC filter circuit can eliminate the current ripple caused by the PWM chopper.The simulation and experimental results verify that the Switch-Linear Hybrid (SLH) scheme is of high efficiency and output quality. The bandwidth of the precise current source is 5.4 kHz and the phase margin is 42 degree.