Device for simulating an instantaneous temperature-rise of a semiconductor component in order to protect same

Claim 1

A device for simulating an instantaneous temperature-rise of a semi-conductor power component in a predetermined environment in order to protect same, said component having a semi-conductor junction, a housing and a radiator, said device comprising in combination: (a) first means (TI, R1), for simulating the instantaneous intensity I of the current flowing through said component; (b) second and third means (VM and EC) connected to the first means for respectively simulating the mean value of the said current intensity and the square I 2 eff of the effective current; (c) fourth means (S) connected to the second and third means for summing up said mean current intensity Im and said square I 2 eff of the effective current, with respective weighting coefficients representing predetermined maximum values, in order to simulate the mean power dissipated by said component; (d) fifth, sixth and seventh means (Kτ jb , Kτ br and Kτ ra respectively) connected to said fourth means for simulating the respective time constants of the thermal resistances (R jb , R br and R ra ) between the junction and the housing bottom, between the housing and the radiator and between the radiator and the environment; said fifth, sixth and seventh means respectively providing image signals of the said time constants; and (e) eighth means (S 1 ) connected to the fifth, sixth and seventh means, for summing up the said image signals of the respective time constants, with weighting coefficients corresponding to predetermined values of said thermal resistances, said eighth means having an output, whereby an image signal of the temperature-rise undergone by said component is obtained at the output of the said eighth means, wherein said seventh means (Kτ ra ) for simulating the time-constant of the thermal resistance between the radiator and the environment comprise a capacitor (C7), first circuit means, connected to the said fourth means, for charging said capacitor and second circuit means for discharging said capacitor, said first circuit means comprising a first resistor (R 22 ) and a first chopper-switch (CA 1 ), mounted in series with said resistor, and means (B 1 T 1 ) for generating periodic pulses adapted to control said first chopper-switch and said second circuit means comprising a second resistor (R 23 ) and a second chopper-switch (CA 2 ) connected in series with said second resistor.

Claim 2

A device for simulating an instantaneous temperature-rise of a semi-conductor power component in a predetermined environment in order to protect same, said component having a semi-conductor junction, a housing and a radiator, said device comprising in combination: (a) first means (TI, R1), for simulating the instantaneous intensity I of the current flowing through said component; (b) second and third means (VM and EC) connected to the first means for respectively simulating the mean value of the said current intensity and the square I 2 eff of the effective current; (c) fourth means (S) connected to the second and third means for summing up said mean current intensity Im and said square I 2 eff of the effective current, with respective weighting coefficients representing predetermined maximum values, in order to simulate the mean power dissipated by said component; (d) fifth, sixth and seventh means (Kτ jb , Kτ br and Kτ ra respectively) connected to said fourth means for simulating the respective time constants of the thermal resistances (R jb , R br and R ra ) between the junction and the housing bottom, between the housing and the radiator and between the radiator and the environment; said fifth, sixth and seventh means respectively providing image signals of the said time constants; and (e) eighth means (S 1 ) connected to the fifth, sixth and seventh means, for summing up the said image signals of the respective time constants, with weighting coefficients corresponding to predetermined values of said thermal resistances, said eighth means having an output, whereby an image signal of the temperature-rise undergone by said component is obtained at the output of the said eighth means, wherein said seventh means (Kτ ra ) for simulating the time-constant of the thermal resistance between the radiator and the environment comprise a capacitor (C7), first circuit means, connected to the said fourth means, for charging said capacitor and second circuit means for discharging said capacitor, said first circuit means comprising a first resistor (R 22 ) and a first chopper-switch (CA 1 ), mounted in series with said resistor, and means (B 1 T 1 ) for generating periodic pulses adapted to control said first chopper-switch and said second circuit means comprising a second resistor (R 23 ) and a second chopper-switch (CA 2 ) connected in series with said second resistor.

Claim 4

A device for simulating the temperature of the junction of a semi-conductor power component in a predetermined environment in order to protect same, said component having a semi-conductor junction, a housing and a radiator, said device comprising in combination: (a) first means (TI, R1), for simulating the instantaneous intensity (I) of the current flowing through said component; (b) second and third means (VM and EC) connected to the first means for respectively simulating the mean value of the said current intensity and the square (I 2 eff ) of the effective current; (c) fourth means (S) connected to the second and third means for summing up said mean current intensity (Im) and said square (I 2 eff ) of the effective current, with respective weighting coefficients representing predetermined maximum values, in order to simulate the mean power dissipated by said component; (d) fifth, sixth and seventh means (Kτ rb , Kτ br and Kτ ra respectively) connected to said fourth means for simulating the respective time constants of the thermal resistances (R jb , R br and R ra ) between the junction and the housing bottom, between the housing and the radiator and between the radiator and the environment; said fifth, sixth and seventh means respectively providing image signals of the said time constants; and (e) eighth means (S 1 ) connected to the fifth, sixth and seventh means, for summing up the said image signals of the respective time constants, with weighting coefficients corresponding to predetermined values of said thermal resistances, said eighth means having an output, whereby an image signal of the temperature-rise undergone by said component is obtained at the output of the said eighth means, wherein said seventh means (Kτ ra ) for simulating the time constant of the thermal resistance between the radiator and the environment comprise a capacitor (C7), first circuit means, connected to the said fourth means, for charging said capacitor and second circuit means for discharging said capacitor, said first circuit means comprising a first resistor (R 22 ) and a first chopper-switch (CA 1 ), mounted in series with said resistor, and means (B 1 T 1 ) for generating periodic pulses adapted to control said first chopper-switch and said second circuit means comprising a second resistor (R 23 ) and a second chopper-switch (CA 2 ) connected in series with said second resistor; said device further comprising further adder means (S 2 ) having first and second inputs, the first input of said further adder means being connected to the output of said eighth means, and sensor means converting the temperature (Ta) of the said predetermined environment into a further image signal (iTa), said sensor means being connected to the second input of said further adder means.

Claim 5

A device for simulating the temperature of the junction of a semi-conductor power component in a predetermined environment in order to protect same, said component having a semi-conductor junction, a housing and a radiator, said device comprising in combination: (a) first means (TI, R1), for simulating the instantaneous intensity (I) of the current flowing through said component; (b) second and third means (VM and EC) connected to the first means for respectively simulating the mean value of the said current intensity and the square (I 2 eff ) of the effective current; (c) fourth means (S) connected to the second and third means for summing up said mean current intensity (Im) and said square (I 2 eff ) of the effective current, with respective weighting coefficients representing predetermined maximum values, in order to simulate the mean power dissipated by said component; (d) fifth, sixth and seventh means (Kτ rb , Kτ br and Kτ ra respectively) connected to said fourth means for simulating the respective time constants of the thermal resistances (R jb , R br and R ra ) between the junction and the housing bottom, between the housing and the radiator and between the radiator and the environment; said fifth, sixth and seventh means respectively providing image signals of the said time constants; and (e) eighth means (S 1 ) connected to the fifth, sixth and seventh means, for summing up the said image signals of the respective time constants, with weighting coefficients corresponding to predetermined values of said thermal resistances, said eighth means having an output, whereby an image signal of the temperature-rise undergone by said component is obtained at the output of the said eighth means, wherein said seventh means (Kτ ra ) for simulating the time constant of the thermal resistance between the radiator and the environment comprise a capacitor (C7), first circuit means, connected to the said fourth means, for charging said capacitor and second circuit means for discharging said capacitor, said first circuit means comprising a first resistor (R 22 ) and a first chopper-switch (CA 1 ), mounted in series with said resistor, and means (B 1 T 1 ) for generating periodic pulses adapted to control said first chopper-switch and said second circuit means comprising a second resistor (R 23 ) and a second chopper-switch (CA 2 ) connected in series with said second resistor; said device further comprising further adder means (S 2 ) having first and second inputs, the first input of said further adder means being connected to the output of said eighth means, and sensor means converting the temperature (Ta) of the said predetermined environment into a further image signal (iTa), said sensor means being connected to the second input of said further adder means.