Control system of water chilling unit compressor

Abstract

The invention discloses a control system for a compressor of a water chilling unit, which is characterized in that a servo driver dynamically evaluates the load state of the compressor according to the real-time change of condensing pressure and evaporating pressure; the output frequency, the rotating speed and the torque of the permanent magnet synchronous motor are adjusted to achieve coordinated matching of the air displacement and the air suction capacity of the compressor, so that the system operation pressure is stabilized, and compressor overload is prevented. Meanwhile, the pressure change trend serves as one of the control bases and participates in the comprehensive judgment process of the fuzzy control algorithm. In addition, a temperature sensor is arranged to detect the outlet water temperature of the water chilling unit in real time and serve as one of input variables of fuzzy control. And an intelligent fuzzy control module arranged in the servo driver comprehensively analyzes the operation condition of the water chilling unit based on the real-time data of the outlet water temperature deviation, the condensation pressure and the evaporation pressure, dynamically adjusts the operation parameters of the permanent magnet synchronous motor, and realizes the accurate control of the outlet water temperature and the self-adaptive adjustment of the system load.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of compressor control, in particular to a high-efficiency and energy-saving control system of a water chiller compressor. BACKGROUND

[0002] The common compressors of water chillers are screw type and centrifugal type, the motors of which adopt common open asynchronous motors and are matched with related control components. In the refrigeration process of the water chiller, the compressor plays a role in compressing low-temperature and low-pressure refrigerant into high-temperature and high-pressure refrigerant and driving the refrigerant to circulate between the evaporator, the condenser and the expansion valve to realize the continuous operation of the system. In the continuous operation of the system, the most important energy consumption is the continuous working process of the compressor, and in the compression process, the high-efficiency operation of the compression motor should be ensured first, and some manufacturers use frequency converters for control, as shown in FIG. 1. Figure 1 Since this control mode belongs to open-loop control, the control accuracy of the ordinary asynchronous three-phase motor on the speed and torque is poor, the operation noise is large, and the system control is unstable or the energy-saving effect is not obvious.

[0003] The existing motor-driven compressor of the water chiller is mainly driven by the ordinary open asynchronous motor as the power and is assisted by other actuators. The open asynchronous motor drives the compressor, the low-temperature and low-pressure refrigerant flows into the compressor, the compressor compresses the refrigerant into high-temperature and high-pressure gas through mechanical movement by doing work, and the compressed high-temperature and high-pressure refrigerant gas is sent to the condenser. In the condenser, the refrigerant releases heat and becomes liquid, and then reenters the evaporator through the expansion valve to continuously circulate. In the whole continuous process, the open asynchronous motor continuously runs and does work, and will not change the speed because of the change of the load, always keeps the operation at the power frequency, causing the high operation cost of the system, and a high-efficiency and energy-saving control system of the water chiller compressor is urgently needed to be developed. SUMMARY

[0004] One of the technical problems to be solved by the present application is to overcome the defects of the above related technologies and provide a high-efficiency and energy-saving control system of a water chiller compressor.

[0005] The technical solution adopted by the present application to solve the technical problem is as follows: a control system of a water chiller compressor, comprising: a permanent magnet synchronous motor for driving the compressor; a servo driver for driving and controlling the permanent magnet synchronous motor, real-time monitoring the operating parameters of the permanent magnet synchronous motor, and comparing the difference in real time, and correcting the output parameters through the real-time comparison difference; a rotary encoder for quickly and real-timely feeding back the operating parameters of the permanent magnet synchronous motor to the servo driver; a pressure sensor for real-timely monitoring the condensing pressure and the evaporating pressure of the water chiller and feeding back to the PLC controller; a temperature sensor for detecting the outlet water temperature of the chiller and feeding back to the PLC controller; a PLC controller for receiving the condensing pressure, the evaporating pressure and the outlet water temperature and transmitting to the servo driver; The servo driver is internally provided with an intelligent fuzzy control module, which comprehensively analyzes the operating conditions of the chiller based on the real-time data of the outlet water temperature deviation, the condensing pressure and the evaporating pressure, dynamically adjusts the operating parameters of the permanent magnet synchronous motor, realizes the accurate control of the outlet water temperature and the adaptive adjustment of the system load.

[0006] As preferred, the rotating encoder feeds back the operating parameters of the permanent magnet synchronous motor in real time, including the rotating speed and the torque of the permanent magnet synchronous motor.

[0007] As preferred, the pressure sensors are respectively installed on the condensing side and the evaporating side.

[0008] As preferred, the PLC controller is provided with a temperature threshold value, and when the detected value of the outlet water temperature of the chiller exceeds the temperature threshold value, a shutdown instruction is sent to the servo driver. This is used for protecting the safe operation of the chiller.

[0009] As preferred, the PLC controller is provided with a condensing pressure threshold value and an evaporating pressure threshold value, and when the detected values of the condensing pressure and the evaporating pressure of the chiller exceed the corresponding threshold values, a shutdown instruction is sent to the servo driver. This is used for protecting the operation of the chiller under safe pressure.

[0010] Compared with the related art, the present application has the following advantages: the servo driver dynamically evaluates the load state of the compressor according to the real-time changes of the condensing pressure and the evaporating pressure, and when the condensing pressure is too high or the evaporating pressure is too low, the output frequency, the rotating speed and the torque of the permanent magnet synchronous motor are adjusted to realize the coordinated matching of the exhaust volume and the suction volume of the compressor, so as to stabilize the system operating pressure and prevent the overloading of the compressor. At the same time, the servo driver takes the pressure change trend as one of the control bases and participates in the comprehensive judgment process of the fuzzy control algorithm.

[0011] In addition, the temperature sensor is arranged for detecting the outlet water temperature of the chiller in real time and taking it as one of the input variables of the fuzzy control. The intelligent fuzzy control module built in the servo driver can comprehensively analyze the operating conditions of the chiller based on the real-time data of the outlet water temperature deviation, the condensing pressure and the evaporating pressure, dynamically adjust the operating parameters of the permanent magnet synchronous motor, realize the accurate control of the outlet water temperature and the adaptive adjustment of the system load, and further improve the energy-saving effect and the operating stability of the chiller. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 It is the control structure diagram of the existing compressor of the present application.

[0013] Figure 2 is a structural schematic diagram of the control system of the present application. DETAILED DESCRIPTION

[0014] First of all, those skilled in the art should understand that these embodiments are only used to explain the technical principles of the embodiments of the present application, and are not intended to limit the protection scope of the embodiments of the present application. Those skilled in the art can adjust them as needed to adapt to specific application occasions.

[0015] The present application will be further described in detail below in combination with the drawings and specific embodiments.

[0016] A control system of a compressor of a water chiller according to an embodiment of the present application, as shown in the accompanying drawings, comprises a compressor, a permanent magnet synchronous motor, a servo driver, a PLC controller, a rotary encoder, a pressure sensor and a temperature sensor; and the whole is a high-efficiency energy-saving control system of a compressor driven by a permanent magnet synchronous motor of a water chiller. Figure 2 The permanent magnet synchronous motor is used to drive the compressor to work, the servo driver is used to drive and control the permanent magnet synchronous motor, and the running parameters (such as the speed, torque and other parameters) of the permanent magnet synchronous motor are monitored in real time. The rotary encoder can quickly feed back the speed and position and other parameters of the permanent magnet synchronous motor to the servo driver in real time for real-time comparison of the difference value, and the output parameters are corrected through the real-time comparison of the difference value, so that the running control precision of the permanent magnet synchronous motor is optimized and the energy consumption of the compressor working is correspondingly reduced.

[0017] The pressure sensor is installed on the condensing side and the evaporating side respectively, and is used to monitor the condensing pressure and the evaporating pressure, which are two key internal pressure parameters, in real time, and feed back the monitoring signals to the servo driver. The servo driver dynamically evaluates the load state of the compressor according to the real-time changes of the condensing pressure and the evaporating pressure, and when the condensing pressure is too high or the evaporating pressure is too low, the output frequency, speed and torque of the permanent magnet synchronous motor are adjusted to realize the coordinated matching of the exhaust volume and the suction volume of the compressor, so as to stabilize the system operating pressure and prevent the compressor from overloading. At the same time, the servo driver takes the pressure change trend as one of the control bases, and participates in the comprehensive judgment process of the fuzzy control algorithm.

[0018] In addition, the temperature sensor is arranged to detect the outlet water temperature of the water chiller in real time, and take it as one of the input variables of the fuzzy control. The intelligent fuzzy control module built in the servo driver can comprehensively analyze the running conditions of the water chiller based on the real-time data of the outlet water temperature deviation, the condensing pressure and the evaporating pressure, dynamically adjust the running parameters of the permanent magnet synchronous motor, realize the accurate control of the outlet water temperature and the adaptive adjustment of the system load, so as to further improve the energy-saving effect and the running stability of the water chiller.

[0019] In addition, the temperature sensor is arranged to detect the outlet water temperature of the water chiller in real time, and take it as one of the input variables of the fuzzy control. The intelligent fuzzy control module built in the servo driver can comprehensively analyze the running conditions of the water chiller based on the real-time data of the outlet water temperature deviation, the condensing pressure and the evaporating pressure, dynamically adjust the running parameters of the permanent magnet synchronous motor, realize the accurate control of the outlet water temperature and the adaptive adjustment of the system load, so as to further improve the energy-saving effect and the running stability of the water chiller.

[0020] As preferred, the PLC controller is provided with a temperature threshold, and sends a stop command to the servo driver when receiving the outlet water temperature detection value of the water chiller exceeding the temperature threshold.

[0021] As preferred, the PLC controller is provided with a condensing pressure threshold and an evaporating pressure threshold, and sends a stop command to the servo driver when receiving the condensing pressure and evaporating pressure values of the water chiller exceeding their corresponding thresholds.

[0022] The beneficial effects of the present scheme are as follows: 1. The permanent magnet synchronous motor has high magnetic field strength, high speed, high efficiency, high power density, fast response, simple control and other advantages. Compared with ordinary asynchronous motor, the permanent magnet synchronous motor has higher efficiency and lower energy consumption because it does not need to generate a rotating magnetic field.

[0023] 2. The driving motor of the compressor is replaced by a permanent magnet synchronous motor driven by a servo driver, achieving a vector closed-loop control system, and further improving the overall operating efficiency of the compressor system.

[0024] 3. The pressure sensor is added to improve the system protection function.

[0025] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or replacements within the technical scope disclosed in the present application can be easily thought of by those skilled in the art, and should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A control system for a chiller compressor, characterized in that, include: Permanent magnet synchronous motor, used to drive the compressor; Servo drivers are used to drive and control permanent magnet synchronous motors, monitor the operating parameters of permanent magnet synchronous motors in real time, compare the differences in real time, and correct the output parameters based on the differences in real time. A rotary encoder provides rapid, real-time feedback of the permanent magnet synchronous motor's operating parameters to the servo driver. Pressure sensors are used to monitor the condensing and evaporating pressures of the chiller unit in real time and provide feedback to the PLC controller. Temperature sensor is used to detect the outlet water temperature of the chiller unit and feed it back to the PLC controller; The PLC controller is used to receive condensation pressure, evaporation pressure and outlet water temperature and transmit them to the servo driver; The servo driver is equipped with an intelligent fuzzy control module. Based on real-time data of outlet water temperature deviation, condensing pressure and evaporating pressure, the intelligent fuzzy control module comprehensively analyzes the operating conditions of the chiller unit and dynamically adjusts the operating parameters of the permanent magnet synchronous motor to achieve precise control of outlet water temperature and adaptive adjustment of system load.

2. The control system for the chiller compressor according to claim 1, characterized in that, The rotary encoder provides real-time feedback on the operating parameters of the permanent magnet synchronous motor, including the motor's speed and torque.

3. The control system for the chiller compressor according to claim 2, characterized in that, The pressure sensors are installed on the condensation side and the evaporation side, respectively.

4. The control system for the chiller compressor according to claim 3, characterized in that, The PLC controller has a temperature threshold. When it receives a detection value of the outlet water temperature of the chiller unit that exceeds the temperature threshold, it sends a stop command to the servo drive.

5. The control system for the chiller compressor according to claim 3, characterized in that, The PLC controller has condensing pressure threshold and evaporating pressure threshold. When it receives a condensing pressure and evaporating pressure value of the chiller unit that exceeds its corresponding threshold, it sends a stop command to the servo drive.

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