Two-Channel Pressure Control Using an Electric Cylinder and a Solenoid Valve for Electronically Controlled Brake Systems

With the rapid proliferation of electrified vehicles (xEVs), maximizing regenerative energy recovery has become a crucial challenge in realizing zero-emission mobility. In front-wheel-drive (FWD) vehicles, regenerative braking acts only on the front axle, resulting in a braking-force distribution biased toward the front. When uniform hydraulic pressure is applied to both axles, excessive braking force on the front wheels may cause premature wheel lock and hinder the intended regenerative braking effect. To address this issue, it is essential to implement an independent pressure control strategy (two-channel pressure control) that appropriately reduces front pressure according to regenerative force while independently maintaining adequate rear pressure. This study proposes a new two-channel pressure control architecture utilizing a simple and reasonable actuator set consisting of one electric cylinder and one solenoid valve. The electric cylinder generates hydraulic pressure by adjusting piston displacement to supply the required volume, while the solenoid valve provides the necessary differential pressure between front and rear circuits. By separating the feedback control objectives of the two actuators, the system effectively mitigates control interference that may cause pressure deficiency or sluggish response. The proposed control was implemented in a two-box electronically controlled brake system comprising an upper unit (an electric cylinder and a solenoid valve) and a lower unit (conventional ESC actuator). Bench and vehicle-level tests were conducted to evaluate the proposed two-channel pressure control. The results confirmed that the control strategy provided sufficient stability and hydraulic response, thereby enabling smooth regenerative braking coordination. Given this performance, despite employing a minimal actuator configuration, the system was verified to deliver approximately a 1–2% improvement in fuel economy relative to conventional one-channel control.