Compressor preheat control system and air conditioning unit

Abstract

The utility model provides a kind of compressor preheating system, including mutually connected main controller and compressor frequency converter, the motor winding of frequency converter is electrically connected with compressor;The main controller and frequency converter are configured, after the main controller receives start instruction, according to real-time ambient temperature and compressor downtime length, generate preheating instruction;After the frequency converter receives the preheating instruction, low-frequency voltage is output to the motor winding of the compressor and carries out compressor preheating.The utility model further provides a kind of air conditioning unit.The compressor preheating control system and air conditioning unit provided by the utility model utilize the frequency converter and motor winding configured by unit itself to carry out preheating before compressor start, after preheating is completed, the normal driving and control of compressor are carried out again.

Description

Technical Field

[0001] This utility model relates to the field of air conditioning unit technology, and in particular to a compressor preheating control system and an air conditioning unit. Background Technology

[0002] Variable frequency air conditioning units used in rail transit and subway systems typically employ horizontal compressors. Under low outdoor temperatures, after the unit has been idle overnight, the lubricating oil and refrigerant can become miscible, and a large amount of refrigerant will deposit in the compressor crankcase in a liquid state. This leads to a decrease in lubricating oil concentration, failing to meet the compressor's lubrication requirements and potentially causing liquid slugging during startup. To avoid damage to the compressor, it is necessary to preheat it before starting the system to ensure system reliability.

[0003] In existing solutions, most manufacturers of variable frequency air conditioning units for rail transit and subway systems wrap an electric heating strip with a heating power of about 70W around the outer wall of the compressor. Before the compressor starts, the electric heating strip is energized to generate heat and then conducted to the inside of the compressor through the cylinder.

[0004] In existing solutions that add electric heating belts, the electric heating belts are wrapped around the outer wall of the compressor and are also exposed to a low-temperature environment, resulting in high heat loss and low heat transfer coefficient. Usually, the power of electric heating belts is limited and cannot be designed to be too large, which leads to low heating efficiency and long preheating cycles. At the same time, adding this component increases costs, reduces production efficiency, and also reduces reliability. Utility Model Content

[0005] This invention provides a compressor preheating control system and an air conditioning unit. The system uses the unit's built-in frequency converter and motor windings to preheat the compressor before startup. After preheating, the compressor is then driven and controlled normally. The frequency converter's output power directly reaches the motor windings, resulting in low heat loss and high heating efficiency. Furthermore, no new components are required, significantly improving production efficiency and product reliability while reducing manufacturing costs.

[0006] To solve the above-mentioned technical problems, this utility model first provides a compressor preheating control system, which adopts the following technical solution:

[0007] A compressor preheating control system, wherein the compressor is equipped with a frequency converter, includes:

[0008] The main controller is connected to the frequency converter and receives the power-on command;

[0009] The compressor is connected to the frequency converter and has a built-in motor winding, which is connected to the frequency converter.

[0010] The frequency converter is configured to control the motor windings to operate after receiving a start command from the main controller, and the operating heat generated by the motor windings preheats the lubricating oil in the compressor.

[0011] Furthermore, during preheating, the frequency converter outputs a sinusoidal voltage or intermittent commutated DC voltage with a frequency of 5-15Hz to the motor windings.

[0012] Furthermore, the main controller is connected to the frequency converter via a CAN bus or an RS485 communication interface.

[0013] Furthermore, it also includes an ambient temperature sensor connected to the main controller.

[0014] Furthermore, the main controller has a preset table of correspondence between ambient temperature range and preheating time. The main controller obtains the corresponding preheating time from the table based on the real-time ambient temperature collected by the ambient temperature sensor and sends it to the frequency converter.

[0015] Furthermore, the main controller has a built-in timer that records the compressor's running time, shutdown time, and preheating time.

[0016] Furthermore, the compressor is a horizontal compressor, and the motor windings are at least partially immersed in the compressor lubricating oil.

[0017] The second objective of this invention is to provide an air conditioning unit, which adopts the following technical solution:

[0018] An air conditioning unit is provided with a compressor preheating control system as described above.

[0019] In summary, the compressor preheating control system for air conditioning units provided by this utility model has the following advantages compared with the prior art:

[0020] 1. The compressor preheating is achieved by using the compressor's built-in frequency converter and motor windings, which directly heats the lubricating oil inside the compressor, resulting in low heat loss and high preheating efficiency;

[0021] 2. Preheating is performed directly by the motor windings, resulting in a short preheating time and a superior customer experience;

[0022] 3. Preheating is achieved by utilizing the operating heat of existing compressor components, without adding new components, thus reducing costs, increasing production efficiency, and improving reliability.

[0023] The specific embodiments of this utility model will be described in further detail below with reference to the accompanying drawings. Attached Figure Description

[0024] The accompanying drawings, as part of this utility model, are used to provide a further understanding of the present utility model. The illustrative embodiments and descriptions of the present utility model are used to explain the present utility model, but do not constitute an undue limitation of the present utility model. Obviously, the drawings described below are merely some embodiments; those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0025] In the attached diagram:

[0026] Figure 1 This is a connection diagram of a compressor preheating control system according to this utility model;

[0027] In the picture:

[0028] 1. Vehicle controller; 2. Main controller; 3. Ambient temperature sensor; 4. Inverter; 5. Compressor; CN1, Communication interface between main controller and vehicle controller; CN2, Communication interface between main controller and inverter; CN3, Communication interface between inverter and main controller; CN4, Communication interface between ambient temperature sensor and main controller; P, Positive input of inverter bus voltage; N, Negative input of inverter bus voltage; U, U-phase output interface of inverter; V, V-phase output interface of inverter; W, W-phase output interface of inverter.

[0029] It should be noted that the accompanying drawings and text description are not intended to limit the scope of the present invention in any way, but rather to illustrate the concept of the present invention to those skilled in the art by referring to specific embodiments. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. The following embodiments are used to illustrate this utility model, but are not intended to limit the scope of this utility model.

[0031] In the description of this utility model, it should be noted that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0032] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0033] This utility model first provides a compressor preheating system, a main controller connected to the frequency converter, and receiving a start-up command;

[0034] The compressor is connected to the frequency converter and has a built-in motor winding, which is connected to the frequency converter.

[0035] The inverter is configured to control the motor windings to operate upon receiving a start-up command from the main controller, and the operating heat generated by the motor windings preheats the lubricating oil in the compressor. This application provides a compressor preheating system that can be widely used in devices including but not limited to refrigerators, air conditioners, and heat pumps that exchange heat with refrigerant through the action of the compressor 5. In this embodiment, taking an air conditioning unit, especially a vehicle air conditioning unit, as an example, the specific composition and preheating method of the compressor preheating system provided in this application are described.

[0036] A compressor preheating control system includes a main controller 2, such as... Figure 1 As shown, the main controller 2 communicates with the vehicle controller 1 through the main controller-vehicle controller communication interface CN1. The vehicle controller 1 sends a control command to the main controller 2 to start the air conditioning unit through the main controller-vehicle controller communication interface CN1. The main controller 2 receives the control command and determines whether the received control command controls the air conditioning unit to operate in heating mode or cooling mode, and further determines whether the compressor 5 needs to be preheated.

[0037] In air conditioning units ( Figure 1 An ambient temperature sensor 3 is installed on the housing (not shown). The ambient temperature sensor 3 is connected to the main controller 2 via a CAD bus or a 485 communication bus through the communication interface CN4 between the ambient temperature sensor and the main controller, or electrically.

[0038] The main controller 2 is connected to the inverter 4 configured with the compressor 5. The main controller is equipped with a communication interface CN2 between the main controller and the inverter, and the inverter 4 is equipped with a communication interface CN3 between the inverter and the main controller. The two interfaces are connected via a CAD bus or a 485 communication bus, or electrically.

[0039] Inverter 4 is electrically connected to compressor 5, such as Figure 1As shown, the inverter 4 is equipped with a positive input P of the inverter bus voltage and a negative input N of the inverter bus voltage for supplying power to the inverter 4; it is also equipped with an inverter U-phase output interface U, an inverter V-phase output interface V and an inverter W-phase output interface W. The inverter 4 is electrically connected to the compressor 5 through the three-phase interface. Furthermore, the inverter 4 can be electrically connected to at least the motor windings of the compressor 5, and output a sinusoidal voltage or intermittent commutated DC voltage with an output frequency of 5-15Hz for preheating to the motor windings. In this voltage mode, the motor windings operate, generating operating heat to preheat the compressor 5.

[0040] In this embodiment, the compressor 5 is a horizontal compressor. When static, part or most of the motor winding is immersed in the oil sump. The motor winding generates operating heat under the sinusoidal voltage or intermittent commutated DC voltage delivered by the frequency converter 4 and exchanges heat with the oil sump, thereby achieving preheating of the lubricating oil and effective evaporation of the refrigerant.

[0041] The main controller 2 receives the start-up command from the vehicle controller 1 through the main controller-vehicle controller communication interface CN1, and determines the operating mode of the air conditioning unit, such as cooling mode or heating mode. It also obtains the real-time outdoor ambient temperature provided by the ambient temperature sensor 3 and the shutdown duration of the compressor 5 through the ambient temperature sensor and the main controller interface CN4 to determine whether the compressor 5 needs to be preheated. If no preheating is required, the main controller sends the start-up command to the inverter 4 directly through the main controller-inverter communication interface CN2 and the inverter-main controller communication interface CN3. If preheating is required, a preheating command is generated and sent to the inverter 4 through interfaces CN3 and CN4. As mentioned above, the inverter 4 executes the corresponding actions according to the received command. For example, when executing the start-up command, the inverter 4 controls the compressor 5 to run at the frequency specified in the command. Or, when executing the preheating command, the inverter 4 sends a 5-15Hz sine wave voltage or intermittent commutated DC voltage to the motor windings, causing the motor windings to operate under this voltage while the compressor 5 does not operate. This generates operating heat in the motor windings, thereby preheating the lubricating oil.

[0042] In this embodiment, after receiving the power-on command from the vehicle controller 1, the main controller 2 compares the collected real-time outdoor ambient temperature and the compressor 5's shutdown duration with the corresponding preset values ​​to determine whether compressor 5 needs preheating and for how long. Specifically:

[0043] The main controller 2 has a built-in timer to track the running and downtime of the air conditioning unit, especially the compressor 5. The running time here refers to the time during which the compressor 5 drives the refrigerant flow in normal cooling or heating mode, excluding the preheating time. After receiving the start command, the main controller 2 first checks the timer's recorded running and downtime of the compressor 5 before this command. If the compressor 5's running time before this start command exceeds (or is greater than or equal to) the preset running time, such as 30 minutes, and the downtime is less than the first preset time, such as 2 hours, then the main controller 2 directly sends the start command to the inverter 4. The compressor 5 starts directly without preheating and executes the corresponding cooling or heating mode according to the start command.

[0044] It should be noted that the preset running time and the first preset time can be adjusted according to the outdoor ambient temperature. For example, the preset running time of 30 minutes and the first preset time of 2 hours described in this embodiment are the basic data, which are applicable to ambient temperatures between 10℃ and 26℃. When the ambient temperature is below 10℃ (inclusive), the ambient temperature is low and the compressor 5 dissipates heat quickly. The preset running time and the first preset time should be appropriately reduced to avoid the compressor 5 dissipating heat quickly and the lubricating oil condensing. When the ambient temperature is above 26℃ (inclusive), the ambient temperature is high and it is not conducive to the heat dissipation of the compressor 5. The time required for the lubricating oil in the compressor 5 to cool down to the condensation point is long. The preset running time and the first preset time can be extended accordingly.

[0045] Preferably, the main controller 2 is equipped with a time-temperature variation curve. This curve is related to the heat dissipation and cooling rate of the compressor 5 under different ambient temperatures. The preset running time and the first preset time are different under different ambient temperatures. The variation curve can be divided into multiple segments, such as three consecutive curves connected end to end: the first segment is when the ambient temperature is less than or equal to 10℃, the second segment is when the ambient temperature is between 10℃ and 26℃, and the third segment is when the ambient temperature is greater than or equal to 26℃.

[0046] The first segment shows that the preset running time and the first preset time decrease linearly as the ambient temperature rises. The second segment is a horizontal line, meaning that the preset running time and the first preset time in this segment do not change with the ambient temperature and are constant values. The third segment shows that the preset running time and the first preset time increase linearly as the ambient temperature rises. Considering that the heat dissipation and cooling efficiency of compressor 5 differs in low-temperature (≤10℃) and high-temperature (≥26℃) environments, the slopes of the first and second segments can be set differently. Preferably, the second segment can also be divided into intervals, and the curves in each interval can use different slopes. Similarly, within the newly divided intervals of the second segment, there is a horizontal line, meaning that within this interval, the preset running time and the first preset time do not change with the ambient temperature. The slope of each segment's curve is determined based on the heat dissipation efficiency of compressor 5 in that temperature range to precisely control the preheating operation.

[0047] Furthermore, if the outdoor ambient temperature and the compressor 5 shutdown time do not meet the aforementioned conditions, the system further determines that when the outdoor ambient temperature is less than or equal to the first preset temperature and the compressor 5 shutdown time is greater than or equal to the first preset time, the main controller 2 generates a preheating command and sends it to the inverter 4. The first preset temperature can be set to 5℃. If the first preset time is 2 hours as mentioned above, that is, when the outdoor ambient temperature is less than or equal to 5℃ and the compressor 5 shutdown time is greater than or equal to 2 hours, it is determined that the compressor 5 needs to be preheated before starting up, and a preheating command is sent to the inverter 4.

[0048] Preferably, the main controller 2 has a preset table showing the correspondence between ambient temperature and preheating time. This table contains multiple consecutive ambient temperature ranges, each corresponding to a preheating time. For example, it can be set as follows:

[0049] When 0℃ < outdoor ambient temperature ≤ 5℃, the preheating time is a minutes;

[0050] When -5℃ < outdoor ambient temperature ≤ 0℃, the preheating time is b minutes;

[0051] When -10℃ < outdoor ambient temperature ≤ -5℃, the preheating time is c minutes;

[0052] When -20℃ < outdoor ambient temperature ≤ -10℃, the preheating time is d minutes;

[0053] Where a < b < d < d.

[0054] In this embodiment, the correspondence between the ambient temperature range and the preheating time is shown in Table 1:

[0055] Table 1: Relationship between ambient temperature and preheating time

[0056] 0℃<T≤5℃ 3min(a) -5℃<T≤0℃ 6min(b) -10℃<T≤-5℃ 10 min (c) -20℃<T≤-10℃ 15 min (d)

[0057] The main controller 2 obtains the corresponding preheating time from the corresponding relationship table based on the real-time outdoor ambient temperature, and sends the obtained preheating time along with the preheating command to the frequency converter 4, which then performs the corresponding preheating operation.

[0058] It should be noted that the preheating time of compressor 5 shown in Table 1 is only an example. In actual applications, the preheating time will vary depending on the specifications of compressor 5, its rated power, and the type of lubricating oil used.

[0059] After the main controller 2 sends the preheating command, the timer inside the main controller 2 starts the preheating countdown. When the countdown ends, the main controller 2 sends a preheating end command to the frequency converter 4, and simultaneously issues a compressor 5 start (air conditioning unit start) command, operating mode, and target frequency. The timer starts counting and records the running time of the compressor 5 for use in determining whether preheating is needed during the next startup.

[0060] As mentioned earlier, the main controller 2 of the air conditioning unit connects to the outdoor ambient temperature sensor 3 via the CN4 interface to detect the outdoor ambient temperature and simultaneously record the duration of the last compressor 5 operation and the duration since it stopped. When the vehicle controller sends a cooling or heating mode command to the air conditioning main controller 2 via the CN1 interface between the vehicle controller and the main controller, the main controller 2 determines whether compressor 5 needs preheating. If preheating is required, the main controller 2 sends the preheating command and preheating time to the compressor inverter 4 via the CN2 and CN3 communication ports shown in the diagram above. The main controller 2 then starts a preheating time countdown. Once the countdown ends, the main controller 2 sends a preheating end command to the compressor inverter 4 and simultaneously sends a compressor 5 start command and target frequency. If preheating is not required, the main controller 2 directly sends the compressor 5 start command and target frequency to the compressor inverter 4.

[0061] In this embodiment, taking a vehicle-mounted air conditioning unit as an example, the compressor preheating control system and specific preheating control method provided in this application are introduced. However, the compressor preheating control system provided in this application can be widely applied to any device that needs to use the compressor 5, including but not limited to air conditioning units, refrigerators, and heat pump systems of any nature. Depending on the device used, the connection method and setting position of each component in the compressor preheating control system described above can be adaptively adjusted to achieve the preheating control described above. The above description should not be regarded as a limitation on the scope of application of this application. For example, when the compressor preheating control system described above is a common household air conditioner, there is no need to set up a vehicle controller 1, and there is no need to set up a vehicle controller and main controller interface CN1 on the main controller 2. The main controller 2 directly receives the start command and, as described above, performs compressor preheating control based on data such as ambient temperature, running time of the front compressor 5, and shutdown time.

[0062] In summary, the compressor preheating control system, preheating method, and air conditioning unit provided by this utility model have the following advantages compared with the prior art:

[0063] 1. The compressor preheating is achieved by using the compressor's built-in frequency converter and motor windings, which directly heats the lubricating oil inside the compressor, resulting in low heat loss and high preheating efficiency;

[0064] 2. Preheating is performed directly by the motor windings, resulting in a short preheating time and a superior customer experience;

[0065] 3. Preheating is achieved by utilizing the operating heat of existing compressor components, without adding new components, thus reducing costs, increasing production efficiency, and improving reliability.

[0066] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model in any way. Although the present utility model has been disclosed above with reference to a preferred embodiment, it is not intended to limit the present utility model. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present utility model. The implementation schemes in the above embodiments can be further combined or replaced. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present utility model without departing from the scope of the present utility model shall still fall within the scope of the present utility model.

Claims

1. A compressor preheating control system, wherein the compressor is equipped with a frequency converter, characterized in that: include, The main controller is connected to the frequency converter and receives the power-on command; The compressor is connected to the frequency converter and has a built-in motor winding, which is connected to the frequency converter. The frequency converter is configured to control the motor windings to operate after receiving a start command from the main controller, and the operating heat generated by the motor windings preheats the lubricating oil in the compressor.

2. The compressor preheating control system as described in claim 1, characterized in that: During preheating, the frequency converter outputs a sinusoidal voltage or intermittent commutated DC voltage with a frequency of 5-15Hz to the motor windings.

3. The compressor preheating control system as described in claim 1, characterized in that: The main controller and the frequency converter are connected via a CAN bus or an RS485 communication interface.

4. A compressor preheating control system as described in claim 1, characterized in that: It also includes an ambient temperature sensor connected to the main controller.

5. A compressor preheating control system as described in claim 4, characterized in that: The main controller has a preset table of correspondence between ambient temperature range and preheating time. The main controller obtains the corresponding preheating time from the table based on the real-time ambient temperature collected by the ambient temperature sensor and sends it to the frequency converter.

6. A compressor preheating control system as described in claim 1, characterized in that: The main controller has a built-in timer that records the compressor's running time, shutdown time, and preheating time.

7. A compressor preheating control system as described in claim 1, characterized in that: The compressor is a horizontal compressor, and the motor windings are at least partially immersed in the compressor lubricating oil.

8. An air conditioning unit, characterized in that: The system is equipped with a compressor preheating control system as described in any one of claims 1 to 7.

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