Driving controlling apparatus for linear compressor and method thereof

A driving controlling apparatus for a linear compressor, comprising:

• a current detecting unit for detecting a current of a motor of the linear compressor;
• a voltage detecting unit for detecting a voltage of the motor of the linear compressor;
• a stroke detecting unit for calculating a stroke using the detected current and the detected voltage;
• a controlling unit for determining an overload state based on a comparison result between a reference phase difference and a phase difference between the detected current and the calculated stroke, and outputting a mode selection control signal for selecting a voltage control mode or a current control mode based on the determining result;
• a first comparing unit for comparing a current command value with a current applied to a linear motor when the current control mode is selected by the mode selection control signal, and outputting a current compensation signal based on the comparison result;
• a second comparing unit for comparing a voltage command value with a voltage applied to the linear motor when the voltage current control mode is selected by the mode selection control signal, and outputting a voltage compensation signal based on the comparison result;
• a pulse width modulation (PWM) controlling unit for outputting a PWM control signal to vary the current or the voltage applied to the linear motor based on the current compensation signal or the voltage compensation signal;
• and
• an inverter for varying the current applied to the linear motor or the voltage applied to the linear motor based on the PWM control signal,
• wherein when the phase difference between the detected current and the calculated stroke is smaller than the reference phase difference, the controlling unit determines an overload state to thus implement a voltage control mode, and when the phase difference between the current and the stroke is larger than the reference phase difference, the controlling unit determines a normal load state to thus implement a current control mode, and
• wherein in the current control mode, when the stroke is consistent with a stroke command value, the controlling unit maintains the current applied to the linear motor, when the stroke is larger than the stroke command value, the controlling unit decreases the current applied to the linear motor, and when the stroke is smaller than the stroke command value the controlling unit continuously increases the current applied to the linear motor.

A driving controlling method for a linear compressor driven with a constant stroke command value, the method comprising:

• detecting a voltage or a current applied to a linear motor thereby calculating a stroke;
• detecting a phase difference between the calculated stroke and a current;
• and
• comparing the detected phase difference with a reference phase difference, selecting a voltage control mode or a current control mode based on the comparison result, and thereby driving the linear motor,
• wherein driving the linear motor comprises:
• when the phase difference between the current and the calculated stroke is smaller than the reference phase difference, determining as an overload state and thereby implementing a voltage control mode, and
• when the phase difference between the current and the calculated stroke is larger than the reference phase difference, determining a normal load state and thereby implementing a current control mode, and
• the implementing the current control mode comprises:
• when the stroke is consistent with a stroke command value, maintaining the current applied to the linear motor,
• when the stroke is larger than the stroke command value, decreasing the current applied to the linear motor, and
• when the stroke is smaller than the stroke command value, continuously increasing the current applied to the linear motor.