Dehua Shi

Design and experiment study of a semi-active energy-regenerative suspension system

A new kind of semi-active energy-regenerative suspension system is proposed to recover suspension vibration energy, as well as to reduce the suspension cost and demands for the motor-rated capacity. The system consists of an energy-regenerative damper and a DC-DC converter-based energy-regenerative circuit. The energy-regenerative damper is composed of an electromagnetic linear motor and an adjustable shock absorber with three regulating levels. The linear motor just works as the generator to harvest the suspension vibration energy. The circuit can be used to improve the systems energy-regenerative performance and to continuously regulate the motors electromagnetic damping force. Therefore, although the motor works as a generator and damps the isolation without an external power source, the motor damping force is controllable. The damping characteristics of the system are studied based on a two degrees of freedom vehicle vibration model. By further analyzing the circuit operation characteristics under different working modes, the double-loop controller is designed to track the desired damping force. The external-loop is a fuzzy controller that offers the desired equivalent damping. The inner-loop controller, on one hand, is used to generate the pulse number and the frequency to control the angle and the rotational speed of the step motor; on the other hand, the inner-loop is used to offer the duty cycle of the energy-regenerative circuit. Simulations and experiments are conducted to validate such a new suspension system. The results show that the semi-active energy-regenerative suspension can improve vehicle ride comfort with the controllable damping characteristics of the linear motor. Meanwhile, it also ensures energy regeneration.

Energy Conservation Analysis and Control of Hybrid Active Semiactive Suspension with Three Regulating Damping Levels

Active suspension has not been popularized for high energy consumption. To address this issue, this paper introduces the concept of a new kind of suspension. The linear motor is considered to be integrated into an adjustable shock absorber to form the hybrid active semiactive suspension (HASAS). To realize the superiority of HASAS, its energy consumption and regeneration mechanisms are revealed. And the system controller which is composed of linear quadratic regulator (LQR) controller, mode decision and switch controller, and the sliding mode control based thrust controller is developed. LQR controller is designed to maintain the suspension control objectives, while mode decision and switch controller decides the optimal damping level to tune motor thrust. The thrust controller ensures motor thrust tracking. An adjustable shock absorber with three regulating levels to be used in HASAS is trial produced and tested to obtain its working characteristics. Finally, simulation analysis is made with the experimental three damping characteristics. The impacts of adjustable damping on the motor force and energy consumption are investigated. Simulation results demonstrate the advantages of HASAS in energy conservation with various suspension control objectives. Even self-powered active control and energy regenerated to the power source can be realized.

Design and test of vehicle suspension system with inerters

A vehicle suspension system with inerters is proposed and its dynamic model is established to analyse its dynamic performance. The structure of the suspension with inerters is also constructed and its form and structural parameters are optimized. Then the rack-and-pinion inerter and the bench test system of suspension are designed. Based on the simulation, bench test is conducted. It has shown that theoretical research is consistent with the test results. Moreover, the structure of the suspension with inerters is so simple, that it can be easily achieved. Consequently the passenger comfort is greatly enhanced and the comprehensive performance of the car has been coordinated. Therefore, simulated analysis and experimental tests in this paper can provide evidence for further research on suspension with inerters.

Research on Speed Optimization Strategy of Hybrid Electric Vehicle Queue Based on Particle Swarm Optimization

Traffic lights intersections are common in cities and have an impact on the energy consumption of vehicles, so it is significant to optimize the velocities of vehicles in urban road conditions. The novel speed optimization strategy for hybrid electric vehicle (HEV) queue that helps reduce fuel consumption and improve traffic efficiency is presented in this paper, where real-world traffic signal information is used to construct the research scenario. The initial values of the target velocities are obtained based on the signal phase and timing (SPAT). Then the particle swarm optimization (PSO) algorithm is used to solve the nonlinear constrained problem and obtain the optimal target velocities based on vehicle to vehicle communication (V2V) and vehicle to infrastructure communication (V2I). The lower controller, which applies rule based control strategy, is designed to split the power of the engine and two electric motors in a power split HEV, which is quite promising because of its advantages in fuel economy. Simulation results demonstrate the superior performance of the proposed strategy in reducing fuel consumption of the HEV queue and improving traffic smoothness.

Mode transition control for single-shaft parallel hybrid electric vehicle using model predictive control approach

Due to the special structure characteristics, the switching process control from pure electrical driving mode to compound driving mode of the single-shaft parallel hybrid powertrain has caught broad attentions from related researches. In this study, a novel mode transition control method based on model predictive control algorithm is proposed to regulate the starting and engaging processes into driveline of the engine via an automatic clutch. According to the system states evolution process, the system control commands, that is, the immediate output torques of the engine, the motor, and the clutch during the mode transition process, are determined online by the proposed model predictive control controller, which derives the optimal control sequences to minimize the defined objective function by adopting quadratic programming in the prediction horizon. To better demonstrate the efficacy of the proposed control method, a simulation analysis platform is built based on MATLAB/Simulink and AVL/Cruise. Simulation results show that the coordinated control method can effectively suppress the vehicle longitudinal jerk within the reasonable range and reduce the clutch wear loss during the mode transition process.

Study on Power Switching Process of a Hybrid Electric Vehicle with In-Wheel Motors

Hybrid electric vehicles with in-wheel motors (IWM) achieve a variety of driving modes by two power sources—the engine and the IWM. One of the critical problems that exists in such vehicle is the different transient characteristics between the engine and the IWM. Therefore, switching processes between the power sources have noteworthy impacts on vehicle dynamics and driving performance. For the particular switching process of the pure electric mode to the engine driving mode, a specific control strategy coordinating clutch torque, motor torque, and engine torque was proposed to solve drivability issues caused by inconsistent responses of different power sources during the mode transition. The specific switching process could be described as follows: the engine was started by IWM with the clutch serving as a key enabling actuator, dynamic torque compensation through IWM was implemented after engine started, and, meanwhile, engine speed was controlled to track the target speed through the closed loop PID control strategy. The bench tests results showed that the vehicle jerk caused during mode switching was reduced and fast and smooth mode switching was realized, which leads to the improvement of vehicle’s riding comfort.