无温度传感器下地铁车辆制动电阻温度在线监测方法

On-line Monitoring Method for Metro Vehicle Braking Resistor Temperature without Temperature Sensor

[目的]为实现无温度传感器下地铁车辆制动电阻的实时温度监测,提出一种无需额外安装传感器的新型制动电阻温度估算方法。[方法]对制动电阻结构和散热过程进行分析,建立由制动电阻单元及其冷却域构成的控制体温度模型,基于能量守恒定律与牛顿冷却定律构建制动电阻单元温度及控制体内冷却空气平均温度方程组,根据制动电阻阻值与温度的关系不断更新制动电阻发热功率并迭代计算,得到制动电阻的实时温度。通过有限元热仿真得到稳态和瞬态下的制动电阻温度分布,对新型制动电阻温度估算方法进行验证。[结果及结论]基于直流牵引网电压与斩波电路占空比计算制动电阻发热功率,无需额外安装传感器,可实现对硬件的纯软件替代。该方法与制动电阻温度估算算法相结合,提高了制动电阻温度估算的可靠性。新型制动电阻温度估算方法得到的制动电阻温度与基于Fluent软件的热仿真结果基本一致,其相对误差在可接受范围内,证明了该估算方法的有效性。制动电阻温度实时估算方法可实现制动电阻温度在线监测,并根据实时监测的制动电阻温度值调节地铁车辆电制动力指令值,提高牵引传动系统的可靠性及安全性。

[Objective]To achieve real-time temperature monitoring of BR(braking resistor)in metro vehicles without temperature sensor,a new temperature estimation method for this purpose without additional sensors is proposed.[Method]By analyzing the BR structure and heat dissipation process,a control body temperature model composed of BR unit and its cooling domain is established.Based on the law of energy conservation and Newton′s law of cooling,equations for the temperature of BR unit and the average temperature of the cooling air within the control body are constructed.According to the relationship between braking resistor value and temperature,the BR heating power is continuously updated and iterative calculations are performed to obtain BR real-time temperature.Finite element thermal simulations are conducted to obtain the BR temperature distribution under steady-state and transient conditions,validating the new BR temperature estimation method.[Result&Conclusion]By calculating BR heating power based on the DC(direct current)traction network voltage and the duty cycle of the chopper circuit,a software-only solution to substitute hardware is achieved,avoiding the need for additional sensors.This method,combined with the BR temperature estimation algorithm,enhances the reliability of BR temperature estimation.The temperature obtained using this new estimation method is consistent with the thermal simulation results based on Fluent software,with relative errors within acceptable limits,proving the effectiveness of the proposed method.The real-time BR temperature estimation method enables BR temperature on-line monitoring and can adjust the electric braking force command values of metro vehicles based on real-time temperature monitoring,thereby improving the reliability and safety of the traction drive system.