Start-up control method of scroll compressor, controller of scroll compressor, and scroll compressor

Abstract

The present application relates to a scroll compressor startup control method, a scroll compressor controller and a scroll compressor. In one aspect, the present application provides a scroll compressor startup control method, the scroll compressor comprising a compression mechanism for compressing working fluid, a motor with a rotor for driving the compression mechanism, and a controller for controlling the operation of the scroll compressor. The startup control method comprises steps S10 to S40. In step S10, the controller determines the initial position of the motor. In step S20, the controller controls the motor to reverse rotation. In step S30, the controller controls the rotor of the motor to position control, so that the rotor rotates to a preset position. In step S40, after positioning, the controller controls the rotor to start forward rotation. The above startup control method can quickly reduce the startup resistance of the scroll compressor.

Description

Technical Field

[0001] This invention relates to a control method for a scroll compressor, and more particularly to a start-up control method for a scroll compressor. Background Technology

[0002] This section provides background information related to the present invention, which does not necessarily constitute prior art.

[0003] Scroll compressors can be used in applications such as refrigeration systems, air conditioning systems, and heat pump systems. A scroll compressor typically consists of a stationary scroll and a moving scroll, which together form a compression mechanism suitable for compressing the working fluid. During operation, the compression mechanism draws in low-pressure fluid from the low-pressure region within the compressor and compresses it. The compressed, high-pressure fluid is then discharged through the exhaust port of the compression mechanism into the high-pressure region within the compressor.

[0004] When a scroll compressor has just stopped running, a significant pressure difference exists between the discharge side (high-pressure zone) and the suction side (low-pressure zone) of the compression mechanism. This pressure difference creates considerable resistance when the scroll compressor restarts. If the scroll compressor is to be restarted immediately after stopping, the starting force of the compressor motor must be sufficient to overcome the resistance caused by the pressure difference. While the motor's starting force is usually sufficient to overcome this resistance, doing so forces a large pressure onto the gas in the high-pressure zone of the compression mechanism. This results in a significant reaction force on the scroll compressor, causing excessive vibration and making it susceptible to damage. As scroll compressors are designed to be smaller, the vibration during startup (especially immediately after shutdown) becomes more severe. Furthermore, especially when starting immediately after shutdown, the probability of startup failure due to inappropriate acceleration of the motor rotor is higher. Moreover, the large pressure difference at this time can also cause a sharp increase in the instantaneous current of the compressor motor, adversely affecting the compressor. These problems urgently need to be addressed or improved. Summary of the Invention

[0005] The first technical problem this invention aims to solve is to rapidly reduce the starting resistance of a scroll compressor. Another technical problem this invention aims to solve is to increase the success rate of starting a scroll compressor. A further technical problem this invention aims to solve is to reduce the damage caused to the scroll compressor during startup.

[0006] Specifically, the present invention provides a start-up control method for a scroll compressor, the scroll compressor comprising a compression mechanism for compressing a working fluid, a motor with a rotor for driving the compression mechanism, and a controller for controlling the operation of the scroll compressor, the start-up control method comprising the following steps:

[0007] Step S10: The controller determines the initial position of the motor;

[0008] Step S20: The controller controls the motor to rotate in the reverse direction;

[0009] Step S30, the controller performs positioning control on the rotor to make the rotor rotate to a preset position; and

[0010] Step S40: After positioning is completed, the controller controls the rotor to start rotating in the forward direction.

[0011] By automatically reversing the motor after the scroll compressor is started (i.e., by reversing the motor through appropriate control), the stationary and moving scroll plates can be further (or even completely) separated. This facilitates the unloading of the high-pressure gas located between the stationary and moving scroll plates when the compressor stops, effectively and quickly reducing the pressure difference between the high-pressure and low-pressure areas within the compression mechanism. This reduces starting resistance, helps the compressor start smoothly and stably, and avoids adverse effects on the compressor, thus extending the service life of the scroll compressor. Especially for smaller scroll compressors, the probability of the moving and stationary scroll plates not separating (especially not completely) when the compressor stops is relatively high. The aforementioned automatic motor reversal technique after startup is particularly effective in reducing the starting resistance of small-sized scroll compressors.

[0012] Preferably, in step S40, the rotational speed of the rotor is monitored in real time within a preset time period calculated from the start of the rotor's forward rotation.

[0013] Preferably, the start-up control method further includes step S50, in which, after the rotor rotates to a speed greater than the preset minimum speed, the controller controls the scroll compressor to enter a closed-loop operation state. If the rotor speed is always less than or equal to the preset minimum speed within a preset time period, step S10 is restarted after step S40 ends.

[0014] Preferably, in step S40, the controller is designed to dynamically adjust the acceleration of the rotor. Dynamically adjusting the acceleration 'a' ensures that the motor does not lose synchronization during startup, which improves the compressor's startup success rate.

[0015] Preferably, the controller is designed to adjust the rotor acceleration according to the load of the scroll compressor, wherein the greater the load of the scroll compressor, the smaller the rotor acceleration is adjusted, and the smaller the load of the scroll compressor, the greater the rotor acceleration is adjusted. In this way, it is more reliable to ensure that the motor does not lose synchronization during startup.

[0016] Preferably, the controller is designed to adjust the acceleration of the rotor based on the operating parameters of the scroll compressor.

[0017] Preferably, in step S20, the controller is designed to cause the motor to rotate in the reverse direction by 10 to 60 revolutions. This design not only achieves further (or even complete) separation between the moving scroll and the stationary scroll, but also minimizes / reduces the potential damage to the scroll compressor caused by motor reversal.

[0018] Preferably, in step S20, the controller is designed to cause the motor to rotate in the reverse direction by 15 to 25 revolutions. This design is particularly advantageous for small scroll compressors.

[0019] Preferably, in step S20, the controller is designed to cause the motor to rotate in the reverse direction at a speed of 10 to 30 revolutions per second. This design further prevents / reduces damage to the scroll compressor.

[0020] Preferably, in step S10, the controller determines the initial position of the motor by detecting changes in the motor's current.

[0021] Preferably, step S30 includes the following steps:

[0022] Step S31: Pre-position the rotor of the motor by applying DC current A1;

[0023] Step S32: Precisely position the rotor of the motor by applying DC current A2.

[0024] Preferably, in step S40, the rotational speed of the rotor is determined by means of an observer.

[0025] Preferably, the controller is designed to stop the scroll compressor and cause the scroll compressor's alarm system to issue an alarm signal if the rotor speed is still less than or equal to a preset minimum speed within a preset time period after repeatedly executing steps S10 to S40.

[0026] The present invention also provides a controller for a scroll compressor, the controller being designed to control the operation of the scroll compressor to perform the steps of the start-up control method described above.

[0027] The present invention also provides a scroll compressor, the scroll compressor including the controller described above.

[0028] In summary, the technical solution of this application can quickly reduce the pressure difference between the intake and exhaust sides of the compression mechanism, quickly and effectively reduce the starting resistance of the scroll compressor, avoid vibration of the scroll compressor during startup and the adverse effects of a sudden increase in motor current on the compressor, and also improve the success rate of starting the scroll compressor. Attached Figure Description

[0029] The foregoing and other features and characteristics of this application will become clearer from the following detailed description with reference to the accompanying drawings, which are merely illustrative and not necessarily drawn to scale. The same reference numerals are used in the drawings to indicate the same parts, in which:

[0030] Figure 1 A cross-sectional schematic diagram of a scroll compressor in the prior art.

[0031] Figure 2 A schematic flowchart of the start-up control method for a scroll compressor according to the present invention.

[0032] Figure 3 A schematic diagram of the circuit connection between the frequency converter and the scroll compressor.

[0033] Reference number list

[0034] 100. Scroll compressor; 200. Frequency converter; 1. Fixed scroll plate; 2. Moving scroll plate; 3. Rotor; 4.

[0035] Crankshaft; I. Compressor inlet; V. Compressor exhaust port. Detailed Implementation

[0036] Preferred embodiments of the invention will now be described in detail with reference to the accompanying drawings. The following description is exemplary in nature and is not intended to limit the invention or its application or use.

[0037] Certain directional terms used in the description of the accompanying drawings below are to be understood as having normal meaning and referring to those directions involved in the normal observation of the drawings, but not necessarily the orientation during actual use of the product. Unless otherwise specified, the directional terms used in this specification are conventional directions as understood by those skilled in the art. Here, "forward" refers to the direction of rotation of the motor rotor when the compression mechanism is performing normal compression operations (generally corresponding to the direction of rotation of the moving scroll relative to the fixed scroll), and "reverse" refers to an orientation opposite to "forward." For example, if "forward" is a clockwise orientation, then "reverse" can be considered as a counterclockwise orientation.

[0038] Figure 1A cross-sectional schematic diagram of a scroll compressor 100 in the prior art is shown. The scroll compressor 100 includes a fixed scroll 1 and a moving scroll 2, which together constitute the compression mechanism of the scroll compressor 100. When the scroll compressor 100 is running, the fixed scroll 1 is stationary, while the moving scroll 2 rotates (i.e., translates or revolves), and the relative revolving motion of the moving scroll 2 and the fixed scroll 1 creates a continuous change in the closed volume. The moving scroll 2 is designed to rotate relative to the fixed scroll 1 under the drive of a crankshaft 4, which in turn rotates under the drive of the rotor 3 of the compressor's motor.

[0039] The scroll compressor also includes a compressor inlet I and a compression mechanism exhaust port V opened on the fixed scroll plate 1. Gas enters the low-pressure area inside the compressor through the compressor inlet I, and then enters the internal space enclosed by the fixed scroll plate 1 and the moving scroll plate 2 through the compression mechanism inlet. After being compressed, it is discharged through the compression mechanism exhaust port V and enters the high-pressure area inside the compressor.

[0040] Figure 2 A schematic flowchart of the start-up control method for a scroll compressor according to the present invention is shown. Figure 3 A circuit connection diagram of the frequency converter 200 and the scroll compressor 100 is shown. In this invention, the startup process mainly includes the following four stages: reversal stage, positioning stage, drive stage, and closed-loop control stage. Furthermore, the scroll compressor may include a controller for controlling the operation of the scroll compressor and a frequency converter for supplying power to the motor of the scroll compressor. The frequency converter may include rectification, filtering, and inversion components. The controller can control the frequency converter, thereby controlling the operation of the scroll compressor (including controlling the startup of the scroll compressor). The following is in conjunction with… Figure 2 and Figure 3 The above stages will be described in detail.

[0041] First, the reversal phase is designed to include steps S10 and S20. In step S10, the controller first needs to determine the initial position of the motor, that is, to find the motor's zero position, thereby determining which direction the motor will rotate in the next step to constitute reversal, preparing for step S20. In this application, the principle of the motor's magnetic field saturation phenomenon is preferably used to find the motor's zero position. Specifically, a current signal is input to the motor, and then the change in the motor's current is observed to determine the motor's zero position. The principle and operation method of using the motor's magnetic field saturation phenomenon to find the motor's zero position are known to those skilled in the art and will not be described in detail herein. Those skilled in the art should understand that other methods known in the prior art can also be used to find the motor's zero position in step S10.

[0042] In step S20, based on the motor zero position determined in step S10, the motor is started to rotate in reverse. Specifically, in order to achieve further separation between the moving scroll and the stationary scroll while minimizing / reducing potential damage to the scroll compressor due to motor reversal, the motor is designed to rotate in reverse for 10 to 60 revolutions. Especially for small scroll compressors, the motor is preferably rotated in reverse for 15 to 25 revolutions.

[0043] To further prevent / reduce damage to the scroll compressor, the reverse rotation speed should preferably not be designed too high. In this application, it is preferred that the motor rotates in reverse at a speed of 10 rpm to 30 rpm, and the reverse rotation time is controlled within the range of 1 to 2 seconds. Motor reversal can be achieved by exchanging two-phase current sampling and two-phase PWM drive signals. Of course, those skilled in the art will understand that other methods known in the art can also be used to reverse the motor.

[0044] The inventors discovered that by automatically reversing the motor after the compressor is started, the fixed scroll plate 1 and the moving scroll plate 2 can be further separated, or even completely separated. This method increases the gas unloading speed in the high-pressure zone of the compression mechanism and effectively promotes the release of gas pressure in the high-pressure zone. This quickly eliminates or reduces the pressure difference between the suction side and the exhaust side of the compression mechanism, thereby helping the compressor to start smoothly and stably and extending the service life of the compressor.

[0045] After completing step S20, the scroll compressor enters the positioning stage, which is completed through step S30. Specifically, in step S30, the controller performs positioning control on the rotor 3 to rotate it to a preset position. After completing step S20, although the compressor can be in a stationary state, the position of the rotor 3 cannot be determined. In order to fix the rotor 3 to a predetermined position (that is, to ensure that the movable scroll plate 2 and the fixed scroll plate 1 are in the specified initial position) for subsequent startup, the controller needs to perform positioning control on the rotor 3.

[0046] Step S30 includes steps S31 and S32. In step S31, the rotor 3 of the motor is first pre-positioned by applying a DC current A1 to the motor. Next, in step S32, the rotor 3 of the motor is precisely positioned by applying a DC current A2 to the motor. The principles and specific implementation methods of the above two-stage DC positioning are well known to those skilled in the art and will not be elaborated upon herein. Furthermore, those skilled in the art should understand that although DC positioning is preferably used in step S30 of this application, the positioning function in this application can also be achieved using existing AC positioning methods or other methods.

[0047] The dragging phase is completed by step S40. After the rotor 3 is positioned, the controller will control the rotor 3 to start rotating.

[0048] In existing technology, during the drive phase, the controller is typically designed to perform open-loop control on the compressor rotor 3, with the rotor 3's acceleration 'a' setpoint (a fixed setpoint). Therefore, the rotor 3's rotational speed at any given time within a preset time period (described below as 10 seconds) will be a fixed preset value. The inventors have discovered that due to the open-loop control of the rotor, the rotor 3 can only rotate at the designed speed during this drive phase, and it cannot adjust according to the different conditions at each start-up of the scroll compressor. This is one of the main reasons for compressor start-up failure. For example, if the scroll compressor has a large load (the load at startup), and the rotor 3 continues to accelerate at a large setpoint acceleration 'a', it is highly likely that the compressor will fail to start.

[0049] To address the aforementioned issues, in this application, the acceleration 'a' is no longer designed as a set value; instead, the controller can dynamically adjust this acceleration 'a'. In other words, the acceleration 'a' dynamically changes within a preset time period calculated from the start of forward rotation of rotor 3 (i.e., from the 0th second to the 10th second after rotor 3 begins forward rotation). Consequently, in step S40, the rotational speed of rotor 3 at any given moment within the preset time period may be different within that time period, and may also be different in each startup procedure.

[0050] In one scenario, the acceleration 'a' can be adjusted according to the load on the scroll compressor. When the load on the scroll compressor is large, the acceleration 'a' can be adjusted to a smaller value; when the load on the scroll compressor is small, the acceleration 'a' can be adjusted to a larger value. In a preferred embodiment, the acceleration of rotor 3 can be further adjusted according to the operating parameters of the scroll compressor. The operating parameters of the scroll compressor include, but are not limited to, current, voltage, and power.

[0051] Dynamically adjusting the acceleration 'a' ensures that the motor does not lose steps during startup, which effectively improves the compressor's startup success rate.

[0052] Furthermore, as mentioned above, since the rotational speed of rotor 3 at any given moment within the preset time period may differ in each startup procedure, it is also necessary to monitor the rotational speed of rotor 3 in real time during step S40. First, a preset minimum rotational speed reference value is set for rotor 3. After detecting that the rotational speed of rotor 3 is greater than the preset minimum rotational speed, the controller immediately controls the scroll compressor to enter the closed-loop control stage.

[0053] The closed-loop control phase is shown in step S50. Successful entry into the closed loop by the scroll compressor signifies a successful start-up. During the closed-loop control phase, the controller calculates the actual position of rotor 3 based on information such as compressor current and DC bus voltage, and performs closed-loop control on the position of rotor 3.

[0054] However, if the rotational speed of rotor 3 measured in step S40 is consistently less than or equal to the preset minimum speed within a preset time period, the scroll compressor will not be switched into closed loop. Figure 2 As shown, the controller will cause the scroll compressor to restart step S10. If this is repeated multiple times (especially, such as...), Figure 2 If, after executing steps S10 to S40 three times (as shown), it still cannot proceed to step S50, the controller will stop the machine and control the scroll compressor's alarm system to issue an alarm signal. This alarm signal includes, but is not limited to, light and sound signals.

[0055] exist Figure 3 The image schematically illustrates the inverter 200 and its circuit connection with the scroll compressor 100.

[0056] The preferred embodiments of the present invention have been described above in conjunction with specific examples. It is understood that the above description is merely exemplary and not restrictive, and various variations and modifications can be conceived by those skilled in the art without departing from the scope of the invention. These variations and modifications are also included within the scope of protection of this application. In particular, although the starting control method described herein includes steps S10 to S60, it is conceivable that the starting control method of this application remains technically feasible and can still achieve the purpose of rapidly reducing the pressure difference even after omitting some steps or sub-steps (such as step S50).

Claims

1. A starting control method for a scroll compressor, characterized in that, The scroll compressor includes a compression mechanism for compressing a working fluid, a motor with a rotor for driving the compression mechanism, and a controller for controlling the operation of the scroll compressor. The start-up control method includes the following steps: Step S10: The controller determines the initial position of the motor; Step S20: The controller controls the motor to rotate in the reverse direction; Step S30, the controller performs positioning control on the rotor to make the rotor rotate to a preset position; and Step S40: After positioning is completed, the controller controls the rotor to start rotating in the forward direction.

2. The start-up control method according to claim 1, characterized in that, In step S40, the rotational speed of the rotor is monitored in real time within a preset time period calculated from the start of the rotor's forward rotation.

3. The start-up control method according to claim 2, characterized in that, It also includes the following steps: In step S50, after the rotor rotates to a speed greater than the preset minimum speed, the controller controls the scroll compressor to enter closed-loop operation. If the rotor speed is always less than or equal to the preset minimum speed within a preset time period, step S10 is restarted after step S40 ends.

4. The start-up control method according to claim 1, characterized in that, In step S40, the controller is designed to dynamically adjust the acceleration of the rotor.

5. The start-up control method according to claim 4, characterized in that, The controller is designed to adjust the acceleration of the rotor according to the load of the scroll compressor, wherein the greater the load of the scroll compressor, the smaller the acceleration of the rotor is adjusted, and the smaller the load of the scroll compressor, the greater the acceleration of the rotor is adjusted.

6. The start-up control method according to claim 5, characterized in that, The controller is designed to adjust the acceleration of the rotor based on the operating parameters of the scroll compressor.

7. The start-up control method according to any one of claims 1 to 6, characterized in that, In step S20, the controller is designed to cause the motor to rotate in the reverse direction from 10 to 60 revolutions.

8. The start-up control method according to claim 7, characterized in that, In step S20, the controller is designed to cause the motor to rotate in the opposite direction for 15 to 25 revolutions.

9. The start-up control method according to claim 7, characterized in that, In step S20, the controller is designed to cause the motor to rotate in the opposite direction at a speed of 10 rpm to 30 rpm.

10. The start-up control method according to any one of claims 1 to 6, characterized in that, In step S10, the controller determines the initial position of the motor by detecting changes in the motor's current.

11. The start-up control method according to any one of claims 1 to 6, characterized in that, Step S30 includes the following steps: Step S31: Pre-position the rotor of the motor by applying DC current A1; Step S32: The rotor of the motor is precisely positioned by applying DC current A2.

12. The start-up control method according to any one of claims 2 to 6, characterized in that, In step S40, the rotational speed of the rotor is determined by means of an observer.

13. The start-up control method according to any one of claims 2 to 6, characterized in that, The controller is designed to stop the scroll compressor and cause the scroll compressor's alarm system to issue an alarm signal if the rotor speed is still less than or equal to a preset minimum speed within a preset time period after repeated execution of steps S10 to S40.

14. A controller for a scroll compressor, characterized in that, The controller is designed to control the operation of the scroll compressor to perform the steps of the start-up control method as described in any one of claims 1 to 13.

15. A scroll compressor, characterized in that, The scroll compressor includes the controller according to claim 14.

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