Device and method for controlling linear compressor

Patent metadata

Field	Value
Publication number	US-9850890-B2
Application number	US-201414570550-A
Country	US
Kind code	B2
Filing date	Dec 15, 2014
Priority date	Dec 19, 2013
Publication date	Dec 26, 2017
Grant date	Dec 26, 2017

Abstract

The control module includes a drive circuitry that drives the linear compressor based on a control signal, a detector that detects a motor current and a motor voltage corresponding to a motor of the linear compressor, an asymmetric current generator that generates an asymmetric motor current by applying a current offset to the detected motor current, and a controller that generates the control signal based on the asymmetric motor current and the detected motor voltage. Such a control module may increase a maximum freezing capacity by appropriately (or optimally) designing (setting) an initial value of a piston in a driving area or an operation area (or a high-efficiency driving area) of a compressor by considering the efficiency aspect, and executing an asymmetric operation in a high-load driving area (or a high freezing capacity driving area).

First claim

What is claimed is:

1. A control module for a linear compressor, comprising: a drive circuitry that is configured to drive the linear compressor based on a control signal; a detector to detect a motor current and a motor voltage corresponding to a motor of the linear compressor; an asymmetric current generator to generate an asymmetric motor current by applying a current offset to the detected motor current; and a controller to detect a stroke based on the detected motor voltage and to generate the control signal based on at least one of the asymmetric motor current, the detected motor voltage or the detected stroke, wherein the control signal adjusts motor speed to control the linear compressor, wherein the controller detects a phase difference between a phase of the asymmetric motor current and a phase of the detected stroke, and wherein the controller generates the control signal such that output power of the linear compressor is controlled based on the phase difference.

2. The control module of claim 1 , wherein the current offset is adjusted based on to an operation mode of the linear compressor, and wherein the operation mode is at least one of a symmetric control mode or an asymmetric control mode, and determined based on a load of the linear compressor or a freezing capacity command value corresponding to the linear compressor.

3. The control module of claim 2 , wherein the symmetric control mode is to set the current offset to ‘0’,
wherein the asymmetric control mode is to set the current offset to a specific value, and wherein the specific value is decided based on the load of the linear compressor or the freezing capacity command value.

4. The control module of claim 1 , wherein the current offset is changed according to a change in a load of the linear compressor or a freezing capacity command value corresponding to the linear compressor.

5. The control module of claim 4 , wherein the controller detects the load of the linear compressor, sets the current offset corresponding to the detected load, and controls the asymmetric current generator to generate the asymmetric motor current to which the set current offset is applied.

6. The control module of claim 5 , wherein the load of the linear compressor is detected based on at least one of an absolute value for a phase difference between a current applied to the linear compressor and the detected stroke, an outer temperature of the linear compressor, an inner temperature of the linear compressor, or a temperature of a condenser and an evaporator within a refrigeration cycle.

7. The control module of claim 4 , wherein the controller sets the current offset corresponding to the freezing capacity command value, and controls the asymmetric current generator to generate the asymmetric motor current to which the set current offset is applied.

8. The control module of claim 1 , wherein a push amount of a piston, which is included in the motor of the linear compressor, due to the current offset is in proportion to a motor constant corresponding to the motor of the linear compressor and the current offset, and wherein the controller adjusts the current offset based on the motor constant.

9. The control module of claim 1 , wherein the linear compressor is a resonance compressor that carries out a resonance operation based on an inductor corresponding to the motor and a virtual capacitor, and wherein the controller integrates the asymmetric motor current, calculates a capacitor voltage by multiplying the integrated value by a specific constant, and implements a function of the virtual capacitor by generating the control signal based on the calculated capacitor voltage.

10. The control module of claim 9 , wherein the control signal is a voltage control signal generated by a pulse width modulation (PWM), and wherein the controller generates a changed PWM reference signal by subtracting the calculated capacitor voltage from a PWM reference signal of a sine wave type to adjust a pulse width of the voltage control signal, and generates the voltage control signal based on the changed PWM reference signal.

11. The control module of claim 9 , wherein the controller controls an operating frequency of the linear compressor to track a mechanical resonant frequency of the linear compressor, and wherein when the operating frequency is adjusted due to a change in the mechanical resonant frequency during an operation of the linear compressor, the controller adjusts the specific constant in such a manner that an electric resonant frequency, which is based on an inductor corresponding to the motor and the virtual capacitor, tracks the adjusted operating frequency.

12. The control module of claim 1 , wherein the controller detects a top dead center of the linear compressor based on the phase difference and generates the control signal based on the detected top dead center.

13. The control module of claim 1 , wherein the controller detects a spring constant corresponding to the motor of the linear compressor based on the phase difference, the asymmetric motor current and the detected stroke, and wherein the controller generates the control signal such that output power of the linear compressor is controlled based on the spring constant, or detects a top dead center of the linear compressor based on the spring constant and generates the control signal based on the detected top dead center.

14. The control module of claim 1 , wherein the motor of the linear compressor comprises a coil including a first coil and a second coil, and a switch is configured to control a coil of the motor to be a combination of at least one of the first coil or the second coil according to a switching control signal.

15. The control module of claim 14 , wherein the controller generates the switching control signal such that the coil corresponding to the motor is the first coil when the load of the linear compressor is greater than a reference load, and wherein the controller generates the switching control signal such that the coil corresponding to the motor to be a combination of the first coil and the second coil when the load of the linear compressor is smaller than the reference load.

16. A linear compressor, comprising:
a fixed member having an inner compression space;
a movable member configured to compress a refrigerant introduced into the compression space while linearly reciprocates within the fixed member;
at least one spring that elastically supports the movable member in a motion direction of the movable member;
a motor connected to the movable member to linearly reciprocate the movable member in an axial direction; and
a control module, wherein the control module comprises the control module of claim 1 .

17. A refrigerator, comprising:
a refrigerator main body;
a linear compressor disposed in the refrigerator main body and configured to compress a refrigerant; and
a control module for the linear compressor, wherein the control module comprises the control module corresponding to claim 1 .

18. A method of controlling a linear compressor, the method comprising: detecting a motor current and a motor voltage corresponding to a motor of the linear compressor; generating an asymmetric motor current by applying a current offset to the detected motor current; generating a control signal based on the asymmetric motor current and the detected motor voltage, wherein the control signal adjusts motor speed to control the linear compressor; and driving the linear compressor based on the control signal, wherein the detecting of the motor current and the motor vo

Assignees

• Lg Electronics Inc

Inventors

• Lim Sungjin
• Ryu Nayi
• Park Sungho

Classifications

• F25B49/022

  Compressor control arrangements · CPC title

• F04B49/06 Primary

  Control using electricity (regulating by means of floats actuating electric switches F04B49/04) · CPC title

• F04B35/04

  the means being electric · CPC title

• F04B35/045

  using solenoids · CPC title

• F04B49/065

  and making use of computers · CPC title