Method for temperature control of refrigerating machines operating with thermoelectric modules

Claim 3

A method as claimed in claim 1, wherein said minimum value of the controlled voltage is adjusted to correspond to a cooling capacity adapted to compensate the internal conductive thermal loss of said thermoelectric module measured under operational conditions.

Claim 4

A method as claimed in claim 2, wherein the voltage of a power supply feeding said thermoelectric module is sensed and, if said sensed voltage becomes lower than a first predetermined value, the amount of electric power applied to said thermoelectric module is reduced by providing a voltage drop within said control range.

Claim 5

A method as claimed in claim 3, wherein the circuit of said thermoelectric module is broken if said sensed power supply voltage sinks below a second predetermined value lower than said first predetermined value.

Claim 6

Apparatus for temperature control of refrigerating machines operating with thermoelectric modules, in which said refrigerating machine comprises a thermally isolated cooling room, a thermoelectric module interconnecting the cooling room with the outer space and a heat exchanger connected to the warm-side surface of said thermoelectric module, characterized in that a sensing means is coupled to said warm side surface of the thermoelectric module to signal its temperature, said sensing means is connected to a control input of a control unit adapted to control the amount of electric power to said thermoelectric module within a predetermined range and to decrease said electric power when said temperature rises above a predetermined minimum, and said control unit is connected to an adjusting means to adjust the lower limit value of said range to a value exceeding zero.

Claim 7

Apparatus for temperature control of refrigerating machines operating with thermoelectric modules, in which said refrigerating machine comprises a thermally isolated cooling room, a thermoelectric module interconnecting the cooling room with the outer space and a heat exchanger connected to the warm-side surface of said thermoelectric module, characterized in that a sensing means is coupled to said warm side surface of the thermoelectric module to signal its temperature, said sensing means is connected to a control input of a control unit adapted to control the amount of electric power to said thermoelectric module within a predetermined range and to decrease said electric power when said temperature rises above a predetermined minimum, and said control unit is connected to an adjusting means to adjust the lower limit value of said range to a value exceeding zero.

Claim 8

Apparatus as claimed in claim 5, characterised in that said thermoelectric module is connected through a controlled switch to a power supply, the controlled switch is controlled by a pulse generator supplying pulses with adjustable energy contents; a first control signal determined by the resistance of said sensing means connected to said warm side heat exchanger, a second control signal determined by the resistance of a second sensing means located within said cooling room and a third control signal proportional to the voltage of said power supply are coupled to the pulse generator to adjust the energy contents of said pulses; and the minimum pulse energy of said pulse generator is adjusted by a potentiometer fed from a source having a stabilised output voltage, said source feeding also said first and second sensing means.

Claim 9

An arrangement as claimed in claim 6, characterised in that said third control signal proportional to the voltage of said power supply is connected to a first input of a comparator, and a signal proportional with the minimum allowed power supply voltage is coupled to a second reference input of said comparator which has an output connected to a blocking input of said controlled switch breaking thereby the feeding circuit of said thermoelectric module if the voltage of the power supply drops below said minimum allowed value.