JP5026867B2 - Compressor and control method of compressor - Google Patents

Description

  The present invention relates to a technique for controlling a compressor.

  Patent Documents 1 and 2 disclose the technology for controlling the compressor. Patent Document 1 is characterized in that, in a compressor having a piston and compressing a refrigerant, the liquefied refrigerant is discharged to enable a stable start-up.

Patent Document 2 is characterized in that, in a gas compressor having a piston, the position of the piston is stopped at a predetermined position to enable stable activation.
JP 2003-28073 A JP 2006-166658 A

  In a compressor that compresses gas, the liquid present in the compressor body and its peripheral path may cause an increase in torque as compared to the drive motor load torque during normal gas compression operation. For example, a lubricating oil having a high viscosity when used in a low temperature environment, a partially liquefied refrigerant when used after being left unused for a long period of time, and the like can cause an increase in torque. As a result, it is considered that stable starting becomes difficult due to the increase in torque especially at starting, and it is considered that the compressor is stopped by the protection function of the compressor. In that case, maintenance work such as restarting the compressor is required, leading to a decrease in reliability. Therefore, in order to perform a stable start-up, it becomes a subject to improve the influence of the load torque increase resulting from these liquids.

  The present invention proposes to solve the above-described problems, and an object of the present invention is to enable stable start-up by suppressing the influence of an increase in compressor load torque caused by liquid.

  In the present invention, when the compressor is driven by a synchronous motor without using a position sensor, when the viscosity of the liquid used for the purpose of lubrication or sealing immediately after the stop is low, a DC command is given to Positioning operation is performed to adjust the shaft to the maximum torque position. As a result, even when the viscosity of the liquid becomes high at the next start-up, the positioning accuracy error is reduced, and the start-up current is effectively acted as the start-up torque. Reduce the chance of stepping out.

  Furthermore, not only when a synchronous motor is driven without using a position sensor, but when driven by a synchronous motor, a predetermined amount of rotation is rotated immediately after startup and then stopped, and then given as a control command value. Drive at the commanded rotation speed. As a result, the liquid existing in the compressor main body and its peripheral path is discharged, an increase in load torque at the time of start-up is suppressed, the possibility of step-out is reduced, and stable start-up is enabled.

  ADVANTAGE OF THE INVENTION According to this invention, the influence of the load torque increase resulting from the liquid which exists in the compressor main body and its peripheral path | route is relieve | moderated, and the starting of a compressor is attained stably.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a configuration diagram of Embodiment 1 of the present invention. In FIG. 1, a control command from the controller 1 is given to the synchronous motor 2, and the compressor body 3 is driven by the rotation of the synchronous motor 2. The compressor body 3 takes in the gas 6 and compresses it. Further, during the operation of the compressor body 3, the oil 7 circulates for the purpose of lubrication and sealing. The oil flows through the compressor body 3 via the oil case 4 and the oil separator 5.

  If the oil is sufficiently circulated in the compressor body 3 and then stopped, and then left in a low temperature environment, the oil temperature becomes low and the viscosity becomes high. At this time, if the compressor is started again, the starting torque may increase compared to the starting torque during the normal gas compression operation. As a result, there is a possibility that the operation of the protection function is invited and the operation stops. In the present invention, start-up stabilization control is performed using the controller 1.

  In the case of position sensorless control of the synchronous motor, the possibility of stopping can be reduced by following the procedure of FIG. After performing the start (S1), a normal start procedure, that is, a positioning operation (S2), a synchronous operation (S3), and a sensorless operation (S4) are performed. Thereafter, when the stop command (S5) is not input, the sensorless operation (S4) is continued. When the stop command (S5) is entered, the judgment of deceleration stop (S6) is made. When the deceleration stop, the output is shut off (S8) after decelerating (S7). S8) is performed.

  Then, after the rotor stop (S9) time has elapsed, positioning operation (S10) is performed again and finally stopped (S11). Generally, since the oil temperature is high and the viscosity is low immediately after the rotor is stopped (S9), the positioning operation (S10) can be performed accurately. As a result, even if the oil temperature is low and the viscosity is high due to the low temperature environment at the next start-up, the positioning operation (S10) has already been completed, so the start-up current effectively acts as the start-up torque, and step-out This reduces the possibility of starting and stabilizes startup.

  Further, in order to mitigate the influence of the increase in the starting torque, the starting is performed according to the procedure of FIG. After starting (S21), operation (S22) of a predetermined rotation amount determined for each compressor, for example, one rotation of the mechanical angle of the synchronous motor is performed and stopped (S23). By this operation, the highly viscous oil present in the compressor body 3 and its peripheral path is discharged. Subsequently, after the rotor of the synchronous motor is stopped (S24), the positioning operation (S25), the synchronous operation (S26), and the sensorless operation (S27), which are normal startup procedures, are performed. Since the oil is discharged by the operation of the predetermined rotation amount (S22), the starting torque is not increased and stable starting can be performed.

  Further, the procedure from S21 to S23 in FIG. 3 is not limited to the position sensorless control of the synchronous motor, and the same effect can be obtained by the control with the position sensor.

  The procedure in FIG. 2 and the procedure in FIG. 3 can be used alone or in combination.

FIG. 1 is a configuration diagram of an embodiment of the present invention. FIG. 2 is a flowchart for explaining an example of the operation of the compressor of FIG. FIG. 3 is a flowchart illustrating an example of the compressor operation of FIG.

Explanation of symbols

1 Controller 2 Synchronous Motor 3 Compressor Body 4 Oil Case 5 Oil Separator 6 Gas Flow 7 Oil Flow 8 Control Command Flow

Claims (6)

A compressor body for compressing gas;
A synchronous motor for driving the compressor body;
In the compressor having a controller that does not have position detection means of the synchronous motor for variably controlling the rotation speed of the synchronous motor,
Immediately after the compressor is stopped, the controller performs a control for positioning operation to give a direct current command so as to align the rotor shaft of the synchronous motor with the maximum torque position. The compressor according to claim 1 , wherein
The controller is characterized in that immediately after the compressor is started, the synchronous motor is rotated by a predetermined amount of rotation and then temporarily stopped, and subsequently, control is performed to drive at a command rotational speed given as a control command value. Compressor. The compressor according to claim 1 or 2,
A compressor characterized in that the compressor body is a screw type, and a liquid for lubrication and sealing is circulated in the compressor body. The compressor according to claim 1 or 2,
The compressor main body is a screw type, and the gas has a characteristic of being partially liquefied under operating conditions of the compressor. In a compressor control method comprising: a compressor main body that compresses gas; a synchronous motor that drives the compressor main body; and a controller that does not have a position detection unit of the synchronous motor that variably controls the rotation speed of the synchronous motor. ,
The compressor control method, wherein the controller performs a positioning operation of the rotor of the synchronous motor immediately after the compressor is stopped. In the compressor control method according to claim 5 ,
Immediately after the compressor is started by the controller, the synchronous motor is rotated by a predetermined amount of rotation and then temporarily stopped, and subsequently driven at a command rotational speed given as a control command value. Control method.

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