US 6,753,665 B2Granted

Linear compressor drive device

AssigneeMatsushita Electric Industrial Co., Ltd.

InventorsMitsuo Ueda, Kaneharu Yoshioka

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Abstract

A linear compressor driving apparatus having an inverter which supplies a driving current of a predetermined frequency to a linear compressor. The linear compressor driving apparatus further includes an inverter controller for controlling the inverter on the basis of resonance frequency information so that the frequency of an output current from the inverter becomes equal to the resonance frequency, and instantaneous values of an output current and an output voltage from the inverter are measured at a phase timing in which an amount of change in the output current of the inverter becomes zero. A piston stroke is calculated from these measured values. In such a linear compressor driving apparatus, a stroke and a top clearance of the piston of the linear compressor can be accurately detected by relatively simple arithmetic processing without using a position sensor.

Claims26

Dependent claims

A linear compressor driving apparatus for driving a linear compressor which has a piston and a linear motor for making the piston reciprocate and which generates a compressed gas by the reciprocating motion of the piston with an AC voltage being applied to the linear motor, said apparatus comprising:

an inverter for outputting an AC voltage and an AC current to the linear motor;
a resonance frequency information output means for outputting resonance frequency information which indicates a resonance frequency of the reciprocating motion of the piston;
a voltage detection means for detecting an output voltage of said inverter to output a voltage detection signal;
a current detection means for detecting an output current of said inverter to output a current detection signal;
an inverter controller for controlling said inverter on the basis of the resonance frequency information so that said inverter outputs a sinusoidal-wave-shaped output voltage and a sinusoidal-wave-shaped output current whose frequencies each match the resonance frequency of the piston reciprocating motion;
a timing detection means for detecting, as a specific phase timing, a phase timing at which a differentiated value of the output current of said inverter becomes zero;
and
a piston velocity calculation means for receiving the voltage detection signal and the current detection signal, and calculating a maximum amplitude of a piston velocity in the piston reciprocating motion on the basis of instantaneous values of the output voltage and the output current output from said inverter at the specific phase timing.

5 more elements

A linear compressor driving apparatus for driving a linear compressor which has a piston and a linear motor for reciprocating the piston and which generates a compressed gas by the reciprocating motion of the piston with an AC voltage being applied to the linear motor, said apparatus comprising:

an inverter for outputting an AC voltage and an AC current to the linear motor;
a resonance frequency information output means for outputting resonance frequency information that indicates a resonance frequency of the piston reciprocating motion;
a current detection means for detecting an output current of said inverter to output a current detection signal;
an inverter controller for controller said inverter on the basis of the resonance frequency information so that said inverter outputs a sinusoidal-wave-shaped output voltage and a sinusoidal-wave-shaped output current whose frequencies each match the resonance frequency of the piston reciprocating motion;
a timing detection means for detecting, as a specific phase timing, a phase timing at which a differentiated value of the output current of said inverter becomes zero;
and
a piston center position calculation means for calculating center position information indicating a piston center position in the piston reciprocating motion on the basis of an instantaneous value of the output current of said inverter at the specific phase timing with reference to a piston position where a pressure difference between the pressure of a cooling medium gas that is discharged from the linear compressor and the pressure of the cooling medium gas that is drawn into the linear compressor becomes zero.

4 more elements

Dependencies are inferred from the claim text.