Electrically interconnected suspension (EIS) has recently emerged for vehicle vibration control. It utilises direct current (DC) motors and electrical networks (EN) to achieve the interconnection of multiple independent suspensions. This innovative EIS system can decouple heave and roll motions, enabling independent vibration control with corresponding EN resistance adjustments. The continuity and accuracy of the resistance adjustments directly influence the vibration control performance of EIS. In this paper, a novel closed-loop current control unit (CCU) is introduced and designed specifically for the EIS system to adjust the EN resistance continuously and accurately, corresponding to the damping variation method in the previous EIS system, thereby achieving high-performance semi-active vibration control. The CCU employs a pair of high-frequency Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs) to create a bidirectional switch in parallel with a resistor. By turning the MOSFET switches on and off with a high-frequency Pulse Width Modulation (PWM) signal with an appropriate duty cycle, the resistance of the EN can be dynamically adjusted, consequently altering the damping characteristics of the EIS. The non-linearities from electrical components like inductors and MOSFET switches are inevitable, potentially causing deviations between the actual EN and its theoretical model. Such deviations might compromise the decoupling characteristics of the EIS. Therefore, a robust sliding mode control (RSMC) strategy is implemented for the resistance control, forming a closed-loop CCU. In addition, two H controllers are designed to obtain the desired vertical force and rotational torque for EIS, which are feedbacked to the CCU, enhancing the control performance. To validate the effectiveness of the EIS with the proposed closed-loop CCU, a series of experiments is conducted on a half-car test rig. The results show significant improvements in vibration control compared to a traditional passive suspension system, demonstrating the potential of this innovative EIS technology to enhance ride comfort.