This study proposes model predictive control (MPC) for onboard ultracapacitors for light rail vehicles using a maximum current constraint. In this study, a Kalman filter is used to estimate the system states. Compared to the PID controller, the MPC-based charging control strategy can solve the maximum current limit problem because it converts the charging problem to an optimization one. Simulation and experiments are carried out to demonstrate the effectiveness of the method.

In this paper, a cooperative charging strategy is proposed for onboard supercapacitors of catenary-free trams. The multi-module charging system consists of n buck converters connected in parallel. The parallel-input parallel-output (PIPO) charging system is modeled mathematically using the averaging method. A cooperative constant-current charging control strategy is designed using the leader-follower consensus approach, where the virtual leader represents the desired charging current for each charging module with a warm-start mechanism. The cooperative charging approach provides dual benefits of both excellent dynamic performance and good reliability. Simulation and experiment results are provided to illustrate the effectiveness of the design.

Active voltage balance has been a popular voltage balance method in high power supercapacitor applications. In this paper, an improved active voltage balance strategy is proposed for renewable generation energy storage systems. First, we propose an improved active voltage balance circuit based on the multi-winding transformer. A clamping capacitor is inserted in the primary side of the transformer to provide a better transient performance. Then a simple but efficient control logic is proposed to decide the sequence of cells to be charged. The supercapacitor is modeled as a RC equivalent circuit. Instead of balancing the terminal voltage of cells, we use an constant-current charging method to identify the parameters of supercapacitors, and calculate the equivalent capacitor voltage, which is further used in the voltage balance. Experiment results are provided to illustrate the effectiveness of the design.

Ultracapacitor has been utilized as main power in light rail vehicles due to its characteristic of high energy-efficiency and fast response. In real application, ultracapacitor needs to be charged rapidly by charging systems when the vehicle parks at platform. However, it is typically challenging to design a rapid high power charging system with good dynamic performance. In this paper, a novel topology for ultracapacitor charging system is proposed to replace traditional buck charging system. Firstly, a three-level buck circuit for ultracapacitor charging system is designed, which halves the voltage stress on IGBT, as well as reduces the value of inductor. And the topology is modified in a way that it has a faster dynamic response. Secondly, the charge control design is reformulated as a model predictive control problem considering current peak constraints. To solve such optimization problem, an extended interior point method is used to simplify the iteration process. Simulation and experiment results are presented to verify the effectiveness of the proposed design.

In this paper, an adaptive extremum seeking control strategy with sliding mode is develop to charge the ultracapacitor light rail vehicles. Compared with existing model-based charging algorithms, the proposed extremum seeking (ES) charging control strategy is model-free, which implies that it can handle the ageing effect of ultracapacitors well. Moreover, a sliding mode mechanism is embedded into the charging controller to suppress the disturbances introduced by sensors. Simulation and experiment results are presented to show the effectiveness of the proposed design.