A hybrid system scheme was designed for the sweeper truck, to solve the problems of high fuel consumption and poor emission performance of traditional sweeper. The control strategy was determined for the hybrid power system. The simulation model of hybrid sweeper truck was built with Matlab/Simulink, and off-line simulation was completed to verify the power system scheme and control strategy, the simulation results indicate that the hybrid sweep truck can realize functions of sweeper and improve the fuel economy.
In order to improve the durability and economy of a hybrid power system composed of a battery and supercapacitors, a control strategy that can reduce fluctuations of the battery current is regarded as a significant tool to deal with this issue. This paper puts forwards a disturbance rejection control strategy for a hybrid power system taking into account the degradation of the battery. First, the degradation estimation of the battery is done by the model-driven method based on the degradation model and Cubature Kalman Filter (CKF). Considering the transient and sinusoidal disturbance from the load in such a hybrid system, it is indispensable to smooth the behavior of the battery current in order to ensure the lifespan of the battery. Moreover, the constraints for the hybrid system should be considered for safety purposes. In order to deal with these demands, a cascaded voltage control loop based on a super twisting controller and proportional integral controller with an anti-windup scheme is designed for regulating the DC bus voltage in an inner voltage loop and supercapacitors’ voltage in an outer voltage loop, respectively. The specific feature of the proposed control method is that it operates like a low-pass filter so as to reduce the oscillations on the DC bus.
Study on emergency power control strategy for AC/DC hybrid power system containing VSC-HVDC