| CPC H01M 8/04992 (2013.01) [H01M 8/04358 (2013.01); H01M 8/04074 (2013.01); H01M 8/04305 (2013.01)] | 12 Claims |
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1. A method for controlling temperature of a thermal management system of a fuel cell, comprising:
acquiring actual temperature of the fuel cell at a current control time, an actual opening degree of a thermostat in the thermal management system of the fuel cell and an inlet coolant temperature at an inlet of a cell stack of the fuel cell;
predicting temperature of the fuel cell at the current control time, with the actual opening degree and the inlet coolant temperature as an input, by using a temperature prediction model;
correcting the predicted temperature based on a current operating condition to obtain a corrected temperature of the fuel cell at the current control time;
calculating a prediction weight factor at the current control time based on the current operating condition; and
determining an adjustment opening degree of the thermostat at the current control time, with a target temperature, the actual temperature, the corrected temperature and the prediction weight factor of the fuel cell as an input, by using a Proportional Integral Differential (PID) controller;
wherein the temperature prediction model comprises
 wherein Tout,pre is the predicted temperature in unit of ° C.; ε1 is a first weight factor; ε2 is a second weight factor; Gu,Ti(Z) is a discrete transfer function with the actual opening degree as an input and the inlet coolant temperature as an output, Gu,Ti(z) comprises temperature transfer delay time between the actual opening degree and the inlet coolant temperature, and z is Z transformation of a discrete system; GTi,To(z) is a discrete transfer function with the inlet coolant temperature as an input and the actual temperature as an output, and GTi,To(z) comprises temperature transfer delay time between the inlet coolant temperature and the actual temperature; utv is the actual opening degree in unit of °; Hu is a mean value of sample values of the actual opening degree in unit of °; Ww,out is a standard deviation of sample values of the actual temperature in unit of ° C.; Wu is a standard deviation of sample values of the actual opening degree in unit of °; Tw,in is the inlet coolant temperature in unit of ° C.; Hw,in is a mean value of sample values of the inlet coolant temperature in unit of ° C.; Ww,in is a standard deviation of the sample values of the inlet coolant temperature in unit of ° C.; and Hw,out is a mean value of the sample values of the actual temperature in unit of ° C.;
wherein the correcting the predicted temperature based on a current operating condition to obtain a corrected temperature of the fuel cell at the current control time comprises
acquiring load current of the fuel cell at the current control time and outlet water temperature at an outlet of a heat sink in the thermal management system of the fuel cell; and determining an off-line correction amount for off-line correction of the predicted temperature based on the load current and the outlet water temperature;
calculating a difference between the target temperature and the actual temperature of the fuel cell to obtain an actual error; calculating a difference between the actual temperature and the predicted temperature to obtain a prediction error; and determining an on-line correction amount for on-line correction of the predicted temperature based on the load current, the actual error and the prediction error; and
calculating a sum of the predicted temperature, the off-line correction amount and the on-line correction amount to obtain the corrected temperature of the fuel cell at the current control time;
wherein a calculation formula of the corrected temperature is
Tpre,fix=Tout,pre+Kadapt+KI+Khec,temp;
wherein Tpre,fix is the corrected temperature in unit of ° C.; Tout,pre is the predicted temperature in unit of ° C.; Kadapt is the on-line correction amount in unit of ° C.; KI is a load current correction amount in unit of ° C.; Khec,temp is an outlet water temperature correction amount in unit of ° C.;
wherein a calculation formula of the off-line correction amount is
 wherein KI is the load current correction amount in unit of ° C.; k1 is a first linear parameter; I is the load current in unit of A; b1 is a second linear parameter; Khec,temp is the outlet water temperature correction amount in unit of ° C.; k2 is a third linear parameter; Thec,temp is the outlet water temperature in unit of ° C.; b2 is a fourth linear parameter; and the off-line correction amount is a sum of the load current correction amount and the outlet water temperature correction amount;
wherein the determining an on-line correction amount for on-line correction of the predicted temperature based on the load current, the actual error and the prediction error comprises
determining whether a difference between the load current and a load current at a previous control time is equal to 0;
in response to a determination that the difference between the load current and the load current at the previous control time is not equal to 0, proceeding into a first state, assuming a first counting time as 0, and determining whether the first counting time is greater than a first time threshold and whether an absolute value of the actual error is less than a first error threshold to obtain a first determination result; in a case that the first determination result is NOT, deeming a state of the current control time as the first state, increasing the first counting time by 1, and assuming the on-line correction amount as a first predetermined value; in a case that the first determination result is YES, setting the first counting time to 0, proceeding into a second state, and determining whether an absolute value of the prediction error is greater than a second error threshold to obtain a second determination result; in a case that the second determination result is NOT, deeming a state of the current control time as a second state, and assuming the on-line correction amount as a second predetermined value; in a case that the second determination result is YES, proceeding into a third state, assuming second counting time as 0, and determining whether the absolute value of the prediction error is less than or equal to the second error threshold to obtain a third determination result; in a case that the third determination result is YES, setting the second counting time to 0, proceeding into the second state, and returning to the determining whether an absolute value of the prediction error is greater than a second error threshold; in a case that the third determination result is NOT, determining whether the second counting time is greater than a second time threshold to obtain a fourth determination result; in a case that the fourth determination result is NOT, deeming the state of the current control time as the third state, increasing the second counting time by 1, and assuming the on-line correction amount as a third predetermined value; in a case that the fourth determination result is YES, setting the second counting time to 0, proceeding to a fourth state, assuming third counting time as 0, and determining whether the third counting time is greater than a third time threshold to obtain a fifth determination result; in a case that the fifth determination result is YES, setting the third counting time to 0, proceeding to the second state, and returning to the determining whether an absolute value of the prediction error is greater than a second error threshold; in a case that the fifth determination result is NOT, deeming the state of the current control time as a fourth state, increasing the third counting time by 1, and assuming the on-line correction amount as a fourth predetermined value; and
in response to a determination that the difference between the load current and the load current at the previous control time is equal to 0, acquiring a state of the previous control time; in a case that the state is the first state, returning to the determining whether the first counting time is greater than a first time threshold; in a case that the state is the second state, returning to the determining whether an absolute value of the prediction error is greater than a second error threshold; in a case that the state is the third state, returning to the determining whether the absolute value of the prediction error is less than or equal to the second error threshold; in a case that the state is the fourth state, returning to the determining whether the third counting time is greater than a third time threshold; wherein
a calculation formula of the prediction weight factor is
Wfix=Wd,rp+γs|enow|+γc;
wherein Wfix is the prediction weight factor; Wd,rp is a dynamic response factor determined based on fluctuation of the load current; γs is a positive constant; enow is an actual error between the target temperature and the actual temperature of the fuel cell in unit of ° C.; and γc is a positive constant;
 wherein Wd,rp(k+1) is a dynamic response factor at k+1 control time; Wh is a constant; CI(k) is the counting time of current change upon current continuously changing to k control time in unit of s; τw,0 is a constant; T is a time interval between two adjacent control times in unit of s; θ1 is a constant; and θ2 is a constant;
a calculation formula of the adjustment opening degree is:
 wherein utv,pid is the adjustment opening degree in unit of °; Kp is a proportional parameter of the PID controller; Ki is an integral parameter of the PID controller; Kd is a differential parameter of the PID controller; enow is the actual error between the target temperature and the actual temperature of the fuel cell in unit of ° C.; Wfix is the prediction weight factor; and epre is a correction error between the target temperature and the corrected temperature of the fuel cell in unit of ° C.;
wherein subsequent to determining the adjustment opening degree of the thermostat at the current control time by using the PID controller, the method further comprises controlling a fan and a pump to be matched with adjustment of the thermostat; wherein a formula of controlling the fan and the pump is
 wherein ufan is a fan speed in unit of r/min; ƒ1 is a first calibration logic based on current, which is set by experimental calibration according to actual fan parameters; I is the load current in unit of A; upum is a pump speed in unit of r/min; and ƒ2 is a second calibration logic based on the current, which is set by experimental calibration according to actual pump parameters.
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