Help regarding the error "Time step too small in OrCAD PSpice"  

 Hi all,

   I am in a problem and need help urgently. I am trying to simulate time varying EPR (Equivalent Parallel Resistance) which is a part of SuperCapacitor model in PSpice. The netlist is:

.SUBCKT EPR + -   
.PARAM Eepr=2.8085V Co=100F
.FUNC EPR(time) {TABLE(time,
+60s, 1.3K, 180s, 2.1K, 360s, 2.8K, 480s, 3K, 600s, 3.44K)}
Eepr + - value= {(Eepr*exp(-time/(Co*EPR(time))))}
.MODEL EPR RES (R=1.0 TC1=0.0 TC2=0.0 TCE=0.0 DEV/GAUSS 1% LOT/UNIFORM 5%)
.ENDS

and the simulation file shows an error:

 Time step =  573.4E-12 is too small in Transient Analysis at

Unable to finish transient analysis

The netlist of SuperCapacitor model is:

* source 100F_EPR_3
X_U1         0 N07132 EPR
C_C         N07132 0  94.22 
R_ESR         N00027 N06933  18m 
I_I1         0 N00027 
+PWL 0 0 1 1 264 1 265 0 865 0 866 -1 1123 -1 1124 0 1200 0
S_S1         N00027 N01143 N00027 0 _S1
RS_S1        N00027 0 1G
.MODEL        _S1 VSWITCH Roff=1e6 Ron=1.0 Voff=2.82V Von=2.8V
R_R1         N01143 0  1.3K 
R_Rp         N06933 N07132  10m 
C_C1         N06933 N07132  7.25 

I have no clue why this is happening. I tried to change the RELTOL, VNTOL, ABSTOL, ITL1 and ITL4 parameters in .OPTIONS settings but it did'nt help. Any help will be highly appreciated.

Thanks and Regards,

Shilpa.

I am able to simulate the above circuit without any error. I have done the simulation for 600Sec and I am using 16.5 version.

Looking at your circuit: you have chosen too narrow range for voltage controlling switch _S1, You should relax this if such tight range is not needed. 

Below is the simulation result at my end:


**** 08/22/11 19:03:08 ****** PSpice 16.5.0 (April 2011) ****** ID# 0 ********

 ***


 ****     CIRCUIT DESCRIPTION


******************************************************************************




* source 100F_EPR_3
X_U1         0 N07132 EPR
C_C         N07132 0  94.22 
R_ESR         N00027 N06933  18m 
I_I1         0 N00027 
+PWL 0 0 1 1 264 1 265 0 865 0 866 -1 1123 -1 1124 0 1200 0
S_S1         N00027 N01143 N00027 0 _S1
RS_S1        N00027 0 1G
.MODEL        _S1 VSWITCH Roff=1e6 Ron=1.0 Voff=2.82V Von=2.8V
R_R1         N01143 0  1.3K 
R_Rp         N06933 N07132  10m 
C_C1         N06933 N07132  7.25
.SUBCKT EPR + -   
.PARAM Eepr=2.8085V Co=100F
.FUNC EPR(time) {TABLE(time,
+60s, 1.3K, 180s, 2.1K, 360s, 2.8K, 480s, 3K, 600s, 3.44K)}
Eepr + - value= {(Eepr*exp(-time/(Co*EPR(time))))}
.MODEL EPR RES (R=1.0 TC1=0.0 TC2=0.0 TCE=0.0 DEV/GAUSS 1% LOT/UNIFORM 5%)
.ENDS

.tran 1u 600
.probe
.end

**** 08/22/11 19:03:08 ****** PSpice 16.5.0 (April 2011) ****** ID# 0 ********

 ***


 ****     Resistor MODEL PARAMETERS


******************************************************************************




               X_U1.EPR       
           R    1           


**** 08/22/11 19:03:08 ****** PSpice 16.5.0 (April 2011) ****** ID# 0 ********

 ***


 ****     Voltage Controlled Switch MODEL PARAMETERS


******************************************************************************




               _S1            
         RON    1           
        ROFF    1.000000E+06
         VON    2.8         
        VOFF    2.82        


**** 08/22/11 19:03:08 ****** PSpice 16.5.0 (April 2011) ****** ID# 0 ********

 ***


 ****     INITIAL TRANSIENT SOLUTION       TEMPERATURE =   27.000 DEG C


******************************************************************************



 NODE   VOLTAGE     NODE   VOLTAGE     NODE   VOLTAGE     NODE   VOLTAGE


(N00027)   -2.8084 (N01143)   -2.8063 (N06933)   -2.8085 (N07132)   -2.8085




    VOLTAGE SOURCE CURRENTS
    NAME         CURRENT


    TOTAL POWER DISSIPATION   0.00E+00  WATTS



          JOB CONCLUDED

**** 08/22/11 19:03:08 ****** PSpice 16.5.0 (April 2011) ****** ID# 0 ********

 ***


 ****     JOB STATISTICS SUMMARY


******************************************************************************



  Total job time (using Solver 1)   =         .09