초록 ▼

A closed-loop, temperature-controlled cooling system includes a Stirling cycle refrigerator driven by a dc motor, wherein the motor excitation derives from pulse width modulation. Temperature control of the cooling system is provided by a temperature-sensitive bridge circuit which responds to variat

A closed-loop, temperature-controlled cooling system includes a Stirling cycle refrigerator driven by a dc motor, wherein the motor excitation derives from pulse width modulation. Temperature control of the cooling system is provided by a temperature-sensitive bridge circuit which responds to variations in temperature by generating an error voltage which effects a change in the modulator duty cycle. The amount of cooling is directly related to the average voltage applied to the motor, which is a function of the modulator duty cycle and the amplitude of the supply voltage. A compensation circuit is disclosed which responds to variations in the voltage amplitude of an unregulated supply by coupling an error signal to the bridge circuit to thereby affect the modulator duty cycle.

대표청구항 ▼

In a control system including a sensing bridge circuit for producing an error voltage in response to deviations from a predetermined sensed parameter, and a modulator-driver circuit coupled to said bridge circuit, to a direct voltage power supply and to a load circuit, said modulator-driver circuit

In a control system including a sensing bridge circuit for producing an error voltage in response to deviations from a predetermined sensed parameter, and a modulator-driver circuit coupled to said bridge circuit, to a direct voltage power supply and to a load circuit, said modulator-driver circuit providing pulses of the voltage of said power supply to said load circuit, said modulator-driver circuit being responsive to said bridge circuit error voltage for establishing the width of said pulses, said load circuit being responsive to an average voltage level applied thereto, said average voltage level being the product of the voltage of said direct-voltage power supply multiplied by the pulse duty cycle, an apparatus for compensating for variations in said average voltage level due to variations in said power supply voltage, said apparatus comprising: providing means coupled to said sensing bridge circuit and to said power supply for providing a signal responsive to said voltage of said direct voltage power supply, said signal affecting the balance of said sensing bridge circuit such that a change in said power supply voltage effects a change in the width of said driver circuit pulses.