Heat pump compressor control method and system based on pressure-temperature double closed loop coupling

Abstract

This application relates to a control method and system for a heat pump compressor based on pressure-temperature dual closed-loop coupling, belonging to the field of heat pump control technology. The method includes: acquiring ambient temperature, blower speed, and condenser target temperature; calculating the feedforward speed; obtaining the target pressure from a table based on the target temperature; acquiring the actual pressure; calculating the pressure-compensated speed using a pressure PID controller; enabling the pressure PID controller during startup; acquiring the actual temperature; calculating the temperature-compensated speed using a temperature PID controller; locking the pressure compensation value and clearing the temperature PID integral during switching; superimposing the feedforward, pressure-compensated, and temperature-compensated speeds to obtain the required speed; outputting the speed control via a speed PID controller; and re-enabling the pressure PID controller when the difference between the target and actual temperatures exceeds the cut-off threshold. This application solves the technical problems of traditional heat pump control relying solely on temperature feedback, resulting in response lag, repeated adjustments required when operating conditions change, and a fixed control strategy that cannot be adaptively adjusted.

Description

Technical Field

[0001] This application relates to the field of heat pump control technology, and in particular to a heat pump compressor control method and system based on pressure-temperature dual closed-loop coupling. Background Technology

[0002] Heat pump compressor control refers to the process of adjusting the compressor speed to change the refrigerant circulation flow rate, thereby controlling the refrigerant temperature at the condenser outlet to reach the target set value. In vapor compression heat pump systems such as air source heat pumps and ground source heat pumps, the compressor, as the core power component, directly determines the refrigerant circulation rate between the evaporator and condenser, thus affecting the condenser's heat release capacity and outlet temperature. Traditional heat pump compressor control methods are based on temperature closed-loop PID control. A temperature sensor installed on the condenser outlet pipe collects the actual temperature, compares it with the target temperature to obtain the temperature deviation, and calculates the compressor speed command through a linear combination of proportional, integral, and derivative parameters. This command drives the compressor inverter to adjust the motor speed, gradually bringing the condenser outlet temperature closer to the target value. In this process, the feedback information of the control system comes only from the temperature sensor, and the control loop is a single temperature closed-loop structure.

[0003] However, traditional methods have the following problems in practical applications. First, temperature sensors have inherent thermal inertia delay. The phase change heat transfer process of refrigerant in the condenser itself has a certain time constant. There is usually a lag of several seconds to tens of seconds between the change in compressor speed and the response of the condenser outlet temperature. This causes the compressor speed adjustment to always lag behind the actual change in the refrigerant state, resulting in a long time for the system to reach the target temperature from start-up. Moreover, it is prone to temperature oscillation due to over-adjustment when approaching the target temperature. Second, single temperature feedback lacks the ability to directly sense changes in refrigerant pressure under external disturbances such as defrosting operation, sudden changes in airflow, or a sudden drop in ambient temperature. The compressor speed needs to undergo multiple corrections to approach the operating point again. The system has a long recovery period after disturbances, and the temperature fluctuation amplitude is large. Third, the PID control parameters and temperature deviation protection thresholds in traditional methods are usually factory-fixed values ​​or manually set values ​​based on experience. They cannot be adaptively adjusted online according to actual operating conditions such as changes in ambient temperature, blower speed, and system operating time. The control quality of the same set of parameters varies significantly in different seasons or different models, resulting in a large amount of debugging work and insufficient versatility. Summary of the Invention

[0004] This application provides a control method and system for a heat pump compressor based on pressure and temperature dual closed-loop coupling, which improves the technical problems in the prior art where single temperature feedback leads to response lag, poor adaptability to sudden changes in operating conditions, and fixed control strategies that cannot be adaptively adjusted.

[0005] This application discloses the following technical solution: In a first aspect, this application provides a heat pump compressor control method based on pressure-temperature dual closed-loop coupling, the method comprising: The ambient temperature, blower speed and condenser target temperature of the heat pump system are obtained, and the compressor feedforward speed is calculated based on the ambient temperature and the blower speed. The target pressure of the condenser is obtained by looking up a table based on the target temperature of the condenser. The actual pressure of the condenser is collected, and the pressure-compensated speed is calculated by a pressure PID closed loop. The pressure PID closed loop is enabled during the startup phase. The actual temperature of the condenser is collected, and the temperature-compensated speed is calculated through a temperature PID closed loop. When switching from a pressure PID closed loop to a temperature PID closed loop, the current value of the pressure-compensated speed is locked and the integral term of the temperature PID closed loop is initialized to zero. The compressor feedforward speed, pressure compensation speed and temperature compensation speed are superimposed to obtain the compressor demand speed, and the compressor control speed is obtained by using the compressor demand speed as the target and the actual compressor speed as feedback through a speed PID closed loop. When the difference between the target temperature and the actual temperature of the condenser exceeds the cut-off threshold, the pressure PID closed loop is re-enabled.

[0006] Secondly, this application provides a heat pump compressor control system based on pressure-temperature dual closed-loop coupling, the system comprising: The feedforward calculation module is used to obtain the ambient temperature, blower speed and condenser target temperature of the heat pump system, and calculate the compressor feedforward speed based on the ambient temperature and the blower speed. The pressure compensation module is used to determine the target pressure of the condenser based on the target temperature of the condenser, collect the actual pressure of the condenser, and calculate the pressure compensation speed through the pressure PID closed loop, wherein the pressure PID closed loop is enabled during the startup phase. The closed-loop switching module is used to collect the actual temperature of the condenser, calculate the temperature-compensated speed through the temperature PID closed loop, and lock the current value of the pressure-compensated speed and initialize the integral term of the temperature PID closed loop to zero when switching from the pressure PID closed loop to the temperature PID closed loop. The speed closed-loop module is used to superimpose the compressor feedforward speed, pressure compensation speed and temperature compensation speed to obtain the compressor demand speed, and obtain the compressor control speed through speed PID closed-loop with the compressor demand speed as the target and the actual compressor speed as the feedback. The back-off control module is used to re-enable the pressure PID closed loop when the difference between the target temperature and the actual temperature of the condenser exceeds the back-off threshold. The parameter tuning module is used to perform offline tuning of the proportional coefficient, integral coefficient, and derivative coefficient of the pressure PID closed loop using the particle swarm optimization algorithm, so as to obtain the tuning parameters of the pressure PID closed loop.

[0007] One or more technical solutions provided in this application have at least the following technical effects or advantages: The technical solution of this application provides a heat pump compressor control method based on pressure and temperature dual closed-loop coupling. First, by acquiring the ambient temperature, blower speed, and condenser target temperature, the ambient temperature and blower speed are input into a feedforward mapping table to query the basic speed value. Then, a decay curve that is negatively correlated with the running time is introduced to dynamically correct the feedforward coefficient. This achieves the matching of the feedforward speed with the heat load demand under different operating conditions and the adaptive adjustment of the feedforward effect as the system stabilizes and gradually withdraws. This solves the problems in the prior art where the feedforward speed deviates greatly from the actual demand and the fixed feedforward value causes overcompensation when approaching steady state.

[0008] Furthermore, by activating the pressure PID closed loop and disabling the temperature PID closed loop when detecting the compressor start command during the start-up phase, the target pressure is obtained by referring to the refrigerant saturation temperature-pressure characteristic table based on the condenser target temperature, and the actual pressure is collected to calculate the pressure-compensated speed. This achieves a control strategy that prioritizes the establishment of condenser pressure by utilizing the rapid response characteristics of the pressure sensor, thus solving the technical problem of slow pressure establishment during the start-up phase and long system time to reach stable operating conditions due to the thermal inertia delay of the temperature sensor.

[0009] Furthermore, by continuously monitoring the fluctuation amplitude of the pressure-compensated speed, a switch is triggered when the fluctuation amplitude is lower than the preset stable threshold and continues to reach the stable duration threshold. During the switch, the current value of the pressure-compensated speed is locked and the temperature PID closed-loop integral term is initialized to zero. At the same time, a minimum switching interval is set to prevent frequent switching, thus achieving a smooth and disturbance-free transition from the pressure closed loop to the temperature closed loop. This solves the technical problems of system disturbance caused by sudden changes in compressor speed during the switching of existing dual closed-loop control and repeated chattering of the state machine near the stability boundary.

[0010] Furthermore, by superimposing the feedforward speed, pressure-compensated speed, and temperature-compensated speed to obtain the compressor's required speed, and using the required speed as the target and the actual speed as feedback, the compressor control speed is output through a speed PID closed loop. This achieves the coordinated unification of multiple control components (feedforward, pressure, and temperature) and the precise tracking and execution of speed commands, solving the technical problems of the lack of a unified superposition mechanism for each control component and the tracking deviation between the actual speed and the required speed.

[0011] Finally, by monitoring the difference between the target temperature and the actual temperature in real time, when the difference exceeds the dynamic cut-back threshold calculated by weighting the speed deviation, temperature change rate, and ambient temperature deviation, the pressure PID closed loop is re-enabled, the temperature PID integral is reset, and the temperature PID is disabled. At the same time, the cut-back cooling time is set to prevent repeated mode jumps. This achieves adaptive cut-back protection from precise temperature control to fast pressure control under abnormal operating conditions, and solves the technical problems of existing methods where temperature deviation cannot be corrected for a long time under external disturbances and control mode jumps repeatedly near the cut-back boundary.

[0012] In summary, the technical solution of this application realizes multi-level coupled control of feedforward calculation of heat pump compressor speed, coarse adjustment of pressure closed loop, fine adjustment of temperature closed loop, execution of speed closed loop and abnormal cut-off protection. Through dual-parameter lookup table and attenuation curve correction, pressure priority enable and temperature integral zeroing, dual threshold switching and cooling time protection, dynamic cut-off threshold adaptive calculation and multi-component superposition and speed closed loop tracking, it effectively improves the technical problems of insufficient accuracy and stability of heat pump compressor speed control caused by single temperature feedback response lag, unsmooth control mode switching and lack of abnormal operating condition protection mechanism in the prior art. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 A schematic diagram of the overall flow of the heat pump compressor control method based on pressure-temperature dual closed-loop coupling provided in the embodiments of this application; Figure 2 A flowchart of the control method for a heat pump compressor control method based on pressure-temperature dual closed-loop coupling provided in this application embodiment; Figure 3 A schematic diagram of the structure of a heat pump compressor control system based on pressure and temperature dual closed-loop coupling provided in an embodiment of this application.

[0015] In the attached diagram, Figure 3 The components represented by each number are described as follows: feedforward calculation module 11, pressure compensation module 12, closed-loop switching module 13, speed closed-loop module 14, back-cut control module 15, and parameter tuning module 16. Detailed Implementation

[0016] This application provides a heat pump compressor control method and system based on pressure and temperature dual closed-loop coupling, which solves the technical problems in the prior art where heat pump control relies only on a single temperature feedback, resulting in slow system response, repeated readjustment when operating conditions fluctuate, fixed control strategy, and low level of intelligence.

[0017] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. It should be noted that the numerical values ​​in the embodiments are for illustrative purposes only and do not constitute a limitation on this application.

[0018] Example 1, as shown in the appendix Figure 1 and attached Figure 2 As shown, this application provides a heat pump compressor control method based on pressure-temperature dual closed-loop coupling, the method comprising the following steps: S100: Obtain the ambient temperature, blower speed and condenser target temperature of the heat pump system, and calculate the compressor feedforward speed based on the ambient temperature and the blower speed; In this embodiment of the application, in scenarios where the initial compressor speed needs to be quickly established when the heat pump starts up or the operating conditions change, in order to obtain the compressor feedforward speed that matches the current operating conditions and provide a reasonable speed reference for the subsequent pressure closed loop and temperature closed loop, it is necessary to obtain the ambient temperature, blower speed and condenser target temperature, and calculate the compressor feedforward speed based on the ambient temperature and blower speed. This solves the technical problems of existing feedforward control output compressor initial speed being significantly different from the actual heat load demand, causing the compressor speed to need to be repeatedly corrected to approach the operating point, slow system response and long time to reach the target temperature, and easy speed overshoot when approaching the target.

[0019] Step S100 in the method provided in this application embodiment includes: The ambient temperature and blower speed of the heat pump system are input into a preset feedforward mapping table to obtain the corresponding base speed value; the current operating time of the compressor is obtained, and a feedforward correction coefficient is determined based on the operating time, wherein the feedforward correction coefficient is negatively correlated with the operating time; the base speed value is multiplied by the feedforward correction coefficient to obtain the compressor feedforward speed. A detailed explanation follows: In this embodiment, the ambient temperature refers to the gas temperature of the external space where the heat pump is located, which is collected by a temperature sensor installed on the air inlet side of the heat pump casing, and the unit is °C. The blower speed refers to the rotational speed of the fan that drives the airflow through the condenser for heat exchange, obtained through the real-time speed signal fed back by the blower driver, and the unit is r / min. The condenser target temperature refers to the desired temperature value that the refrigerant at the condenser outlet needs to reach, calculated and issued by the upper-level controller based on the user-set temperature and the current operating conditions, and the unit is °C. The feedforward mapping table refers to a lookup table with ambient temperature and blower speed as two-dimensional inputs and compressor base speed as output, which is pre-established through calibration experiments. The compressor feedforward speed refers to the initial target speed value directly applied to the compressor before closed-loop control intervention, used to make the compressor quickly approach the operating point, and the unit is r / min. The feedforward correction coefficient refers to a multiplicative factor that dynamically adjusts the base speed according to the compressor's running time, with a value range of 0 to 1, starting at 1 at startup and monotonically decreasing as the running time increases.

[0020] The feedforward correction coefficient is determined by looking up a preset decay curve. This decay curve takes the compressor's operating time as input and the feedforward correction coefficient as output, and is obtained by fitting data on the impact of the compressor's feedforward speed on the system's dynamic response collected at different operating time nodes. For example, a typical decay curve is non-linear, maintaining a coefficient of 1.0 during the initial startup phase (0-5 seconds), rapidly decaying from 1.0 to 0.3 between 5 and 30 seconds, slowly decaying from 0.3 to 0.1 between 30 and 60 seconds, and remaining constant at 0.1 after 60 seconds. The lower limit of the decay curve, 0.1, is determined based on the ratio of the compressor's minimum safe speed to its base speed, ensuring that the feedforward speed is never lower than the compressor's minimum operating speed requirement.

[0021] In this step, firstly, in order to match the initial speed of the compressor with the actual heat load, the collected ambient temperature and blower speed need to be input into a preset feedforward mapping table. The corresponding basic speed value is obtained by looking up the table in two dimensions, which can make the feedforward speed close to the actual needs under different operating conditions. For example, when the ambient temperature is -7℃ and the blower speed is 2500r / min, the basic speed value of 3800r / min is obtained by looking up the table.

[0022] Furthermore, in order to gradually reduce the feedforward effect as the system approaches the target, it is necessary to obtain the current running time of the compressor and determine the feedforward correction coefficient by looking up a table through a preset decay curve. This correction coefficient is 1.0 at the moment of startup and gradually decays to the steady-state lower limit of 0.1 as the running time increases. This can solve the problem of overcompensation caused by a fixed feedforward value when approaching steady state. For example, the correction coefficient is 0.6 when the running time is 10s, decays to 0.3 when it is 30s, and decays to 0.1 when it is 60s and remains thereafter.

[0023] Finally, the base speed value is multiplied by the feedforward correction coefficient to obtain the compressor feedforward speed, which provides a strong feedforward acceleration response in the early stage of startup and gradually withdraws after the system tends to stabilize to reduce interference to the closed loop. For example, the base speed value of 3800 r / min is multiplied by the correction coefficient of 0.3 to obtain the feedforward speed of 1140 r / min.

[0024] For example, taking the operation of a 3-horsepower air source heat pump in winter heating mode as an example, the ambient temperature is -7℃, the blower speed is 2500 r / min, and the condenser target temperature is 55℃. The ambient temperature and blower speed are input into the feedforward mapping table, and the base speed value is found to be 3800 r / min. At startup, the running time is 0 seconds, the correction coefficient is 1.0, and the feedforward speed is 3800 r / min; after 10 seconds, the correction coefficient is 0.6, and the feedforward speed is 2280 r / min; after 30 seconds, the correction coefficient is 0.3, and the feedforward speed is 1140 r / min; after 60 seconds, the correction coefficient is 0.1 and remains at that level, and the feedforward speed is 380 r / min. The feedforward effect is essentially discontinued, and the pressure closed loop and temperature closed loop take over subsequently.

[0025] In summary, this step obtains the base speed value by jointly looking up the ambient temperature and blower speed in a table, and dynamically adjusts it using a correction coefficient that is negatively correlated with the operating time to generate the compressor feedforward speed. Compared with existing technologies, this step has the following advantages: First, by using a dual-parameter table lookup, the feedforward speed is matched to the heat load requirements under different operating conditions, reducing initial speed deviation; second, the introduction of a correction coefficient that is correlated with the operating time makes the feedforward effect stronger in the initial stage of startup to accelerate the response, and gradually weakens after the system stabilizes to reduce interference with the closed loop, thereby shortening the time to reach the target temperature and reducing speed overshoot.

[0026] S200: The target pressure of the condenser is obtained by looking up the table according to the target temperature of the condenser, the actual pressure of the condenser is collected, and the pressure-compensated speed is calculated by the pressure PID closed loop, wherein the pressure PID closed loop is enabled during the start-up phase. In this embodiment of the application, in the scenario where the compressor feedforward speed and the condenser target temperature have been obtained during the heat pump startup phase, in order to quickly establish the condenser working pressure by utilizing the fast response speed of the refrigerant pressure and avoid the response lag caused by the thermal inertia of the temperature sensor, it is necessary to obtain the condenser target pressure by looking up a table based on the condenser target temperature and collect the actual condenser pressure. The pressure PID closed loop is used to calculate the pressure-compensated speed and enable the pressure PID closed loop during the startup phase. This solves the technical problems of existing control relying solely on temperature feedback, the thermal inertia delay in the temperature sensor response, the compressor speed adjustment lagging behind the actual refrigerant state change, the slow establishment of condenser pressure or overshoot during the startup phase, and the inability of the system to quickly enter a stable operating condition.

[0027] Step S200 in the method provided in this application embodiment includes: The compressor start command is detected. When the start command is detected, the pressure PID closed loop is set to active, and the temperature PID closed loop is set to disabled. The temperature PID closed loop does not participate in speed calculation during the disabled period. A detailed explanation follows: In this embodiment, the condenser target pressure refers to the refrigerant saturation pressure value corresponding to the condenser target temperature, obtained by looking up a pre-stored refrigerant saturation temperature-pressure characteristic table, with units of MPa. The condenser actual pressure refers to the current real pressure of the refrigerant at the condenser outlet, acquired in real time by a pressure sensor installed on the condenser outlet pipeline, with units of MPa. The pressure PID closed loop refers to a proportional-integral-derivative closed-loop controller that takes the deviation between the condenser target pressure and the actual pressure as input and the compressor speed compensation amount as output, used to quickly reduce the pressure deviation. The pressure-compensated speed refers to the speed correction amount calculated by the pressure PID closed loop based on the pressure deviation, superimposed on the compressor feedforward speed to adjust the compressor speed, with units of r / min.

[0028] In this step, firstly, in order to take advantage of the rapid response characteristics of pressure feedback during the startup phase, it is necessary to detect the compressor startup command. When the startup command is detected, the state of the pressure PID closed loop is set to active, so that the pressure PID closed loop starts to calculate the pressure compensation speed based on the pressure deviation. This can quickly establish the condenser pressure in the early stage of startup. For example, when the target condenser temperature is 55℃, the target pressure is 3.2MPa, and the actual pressure is 1.5MPa, a positive pressure deviation of 1.7MPa is generated. The pressure PID outputs a positive pressure compensation speed accordingly to accelerate the pressure rise.

[0029] Furthermore, to avoid interference from the thermal inertia delay of temperature feedback during the initial startup phase, the temperature PID closed-loop must be disabled. During the disabled period, the temperature PID output remains 0 and does not participate in speed calculation. This prevents incorrect compensation from the temperature PID output due to the condenser temperature not yet responding, ensuring that the compressor speed during startup is entirely determined by both the feedforward speed and the pressure-compensated speed. Under the action of the pressure PID closed-loop, the compressor rapidly adjusts its speed based on the pressure deviation during startup, quickly bringing the actual condenser pressure close to the target pressure. This lays the pressure foundation for subsequent switching to the temperature PID closed-loop for precise temperature control.

[0030] For example, taking the operation of a 3HP air source heat pump in winter heating mode as an example, the ambient temperature is -7℃, the blower speed is 2500r / min, the condenser target temperature is 55℃, the start-up time is 0s, the feedforward correction coefficient is 1.0, and the feedforward speed is 3800r / min. The condenser target temperature of 55℃ is obtained by looking up the R410A refrigerant saturation temperature-pressure characteristic table, and the condenser target pressure is 3.2MPa. After the start command is issued, the pressure PID closed loop is activated, and the temperature PID closed loop is disabled. At startup, the actual condenser pressure is 1.5 MPa, deviating from the target pressure of 3.2 MPa by 1.7 MPa. The pressure PID closed loop calculates the output pressure compensation speed of 800 r / min based on the proportional and integral coefficients. After adding the feedforward speed of 3800 r / min, the compressor's required speed is 4600 r / min. As the pressure rises, when the actual pressure reaches 2.8 MPa, the pressure deviation decreases to 0.4 MPa, the pressure compensation speed drops to 400 r / min, and the compressor's required speed is adjusted to 4200 r / min. When the actual pressure approaches 3.2 MPa, the pressure compensation speed approaches 0, and the pressure PID closed loop completes the pressure establishment task. At this point, the runtime is approximately 30 seconds, the feedforward correction coefficient decays to 0.3, the feedforward speed is 1140 r / min, and the system prepares to switch to the temperature PID closed loop.

[0031] In summary, this step activates the pressure PID closed loop and disables the temperature PID closed loop during the startup phase. It leverages the rapid response of refrigerant pressure to generate a pressure-compensated speed, which, together with the feedforward speed, drives the compressor to quickly establish condenser pressure. Compared to existing technologies, this step offers the following advantages: First, it transforms the control target from a temperature quantity with high thermal inertia to a pressure quantity with rapid response, achieving rapid mapping of the target value through the refrigerant temperature-pressure correspondence. Second, it prioritizes enabling the pressure PID closed loop during startup, utilizing the rapid response of the pressure sensor to quickly establish the condenser operating pressure, shortening system startup time and providing a stable pressure foundation for subsequent precise temperature control.

[0032] S300: Collects the actual temperature of the condenser, calculates the temperature-compensated speed through the temperature PID closed loop, and locks the current value of the pressure-compensated speed and initializes the integral term of the temperature PID closed loop to zero when switching from the pressure PID closed loop to the temperature PID closed loop. In this embodiment of the application, when the condenser pressure has reached near the target pressure during the heat pump startup phase and the system is ready to switch to precise temperature control, in order to achieve a smooth transition from the pressure closed loop to the temperature closed loop and avoid system disturbances caused by sudden changes in compressor speed during the switching, it is necessary to collect the actual condenser temperature and calculate the temperature compensation speed through the temperature PID closed loop. At the time of switching, the current value of the pressure compensation speed is locked and the integral term of the temperature PID closed loop is initialized. This solves the technical problems of existing dual closed-loop control, such as the lack of smooth connection between the compressor speed control quantity before and after the control mode switching, the easy occurrence of sudden changes in compressor speed, the significant disturbance of condenser temperature and pressure during the switching process, the need for additional time for the system to recover stability, the lack of quantitative judgment basis for the switching timing, and the reduction of control quality due to switching too early or too late.

[0033] Step S300 in the method provided in this application embodiment includes: The fluctuation amplitude of the pressure-compensated speed is collected. When the fluctuation amplitude remains below a preset stabilization threshold for a period of time, a switch is triggered. During the switch, the output value of the pressure PID closed loop is latched as a constant, and this constant is used as the pressure-compensated speed in subsequent superposition calculations. At the switch moment, the current integral term value of the temperature PID closed loop is read, and the current integral term value is forcibly set to zero, starting integration from zero to avoid output jumps in the temperature PID closed loop at the moment of switch. A detailed explanation follows: In this embodiment, the actual condenser temperature refers to the current true temperature of the refrigerant at the condenser outlet, which is collected in real time by a temperature sensor installed on the condenser outlet pipe, and the unit is °C. The temperature PID closed loop refers to a proportional-integral-derivative closed-loop controller that uses the deviation between the target condenser temperature and the actual temperature as input and the compressor speed compensation amount as output, used to accurately eliminate temperature static error. The temperature compensation speed refers to the speed correction amount calculated by the temperature PID closed loop based on the temperature deviation, superimposed on the compressor feedforward speed and pressure compensation speed to accurately adjust the compressor speed, and the unit is r / min. The pressure compensation speed fluctuation amplitude refers to the difference between the maximum and minimum values ​​of the pressure compensation speed over multiple consecutive sampling periods, used to measure whether the pressure closed-loop output tends to stabilize, and the unit is r / min. The preset stability threshold refers to the upper limit of the fluctuation amplitude for determining whether the pressure compensation speed has entered a stable state; when the fluctuation amplitude is below this value, the pressure is considered stable, and the unit is r / min. The stability duration threshold refers to the minimum continuous time for the pressure compensation speed fluctuation amplitude to remain below the preset stability threshold; after reaching this time, a switching is triggered, and the unit is seconds.

[0034] In this step, firstly, to ensure that the switch to temperature closed loop is only initiated after the pressure has fully stabilized, the pressure compensation speed is continuously collected and its fluctuation amplitude is calculated. The fluctuation amplitude is compared with a preset stabilization threshold. When the fluctuation amplitude is continuously lower than the preset stabilization threshold for a period of time that reaches the stabilization duration threshold, it is determined that the pressure has entered a steady state and the switch is triggered. This can prevent the pressure from deviating again after the temperature closed loop takes over if the switch is initiated too early before the pressure has stabilized. For example, if the preset stabilization threshold is 50 r / min and the stabilization duration threshold is 5 s, the switch is triggered when the difference between the maximum and minimum values ​​of the pressure compensation speed is less than 50 r / min for 5 consecutive seconds.

[0035] Furthermore, in order to retain the compensation component accumulated by the pressure closed loop during the startup phase, the output value of the pressure PID closed loop is latched as a constant during switching. This constant is used as the pressure compensation speed to continue to participate in the superposition calculation of the feedforward speed and the temperature compensation speed. This can prevent the pressure compensation amount from directly returning to zero, which would cause a sudden drop in compressor speed, and keep the compressor speed continuous during the switching process.

[0036] Finally, to avoid output jumps caused by historical integral values ​​during switching of the temperature PID closed loop, the current integral term value of the temperature PID closed loop is read at the switching moment and forced to be set to zero, so that the temperature PID closed loop starts integrating from zero. This can solve the problem of speed compensation jump caused by sudden change in integral term during the switching moment of the temperature PID, and achieve a smooth transition from pressure control to temperature control.

[0037] Step S300 in the method provided in this application embodiment further includes: A minimum switching interval is set. After completing a switch from a pressure PID closed loop to a temperature PID closed loop, further switching is prohibited within this minimum interval to avoid frequent state machine chattering. A detailed explanation follows: In this embodiment, the minimum switching interval refers to the minimum time interval that must be maintained between two adjacent switching operations. Within this duration, the system ignores any new switching triggering conditions, and the unit is seconds (s). State machine chattering refers to the phenomenon where, when the pressure-compensated speed fluctuates repeatedly around a stable threshold, the control state rapidly and repeatedly jumps between the pressure closed loop and the temperature closed loop, causing the compressor speed to change abruptly. Prohibiting further switching means temporarily disabling the switching determination logic within the minimum switching interval, and not performing a state transition even if the switching conditions are met.

[0038] In this step, to prevent the state machine from repeatedly switching due to small fluctuations when the pressure-compensated speed is exactly at the stable boundary, a minimum switching interval needs to be set. The timer is started after a switch from the pressure closed loop to the temperature closed loop is completed. During this time, any switching operation is prohibited from being triggered again. This can eliminate the state machine chattering phenomenon and allow the control state to remain for a sufficient time after the switch to evaluate the control effect of the temperature closed loop. For example, if the minimum switching interval is set to 30 seconds, the system will maintain the temperature closed loop operation for 30 seconds after the switch is completed. Even if the pressure-compensated speed fluctuates again, it will not switch back to the pressure closed loop.

[0039] For example, taking the operation of a 3HP air source heat pump in winter heating mode as an example, under the pressure PID closed-loop action, the actual condenser pressure is close to the target pressure of 3.2MPa, the running time is about 35s, the correction coefficient is about 0.23, and the feedforward speed is about 874r / min. The pressure compensation speed fluctuates between 100r / min and 140r / min, with a fluctuation range of 40r / min, which is lower than the preset stable threshold of 50r / min. After 5s, the stable duration threshold is reached, triggering the switch. At the time of switchover, the pressure compensation speed is latched at 120r / min, the temperature PID integral is cleared to zero, and the initial output temperature compensation speed is 60r / min, with the deviation of 2℃ between the target temperature of 55℃ and the actual temperature of 53℃ as the input. The required speed is the sum of the feedforward speed of 874r / min, the latched pressure compensation speed of 120r / min, and the temperature compensation speed of 60r / min. After the switchover, the temperature closed-loop operation is maintained within a minimum switching interval of 30s.

[0040] In summary, this step quantifies and determines the switching timing by assessing the pressure-compensated speed fluctuation amplitude. During switching, the pressure-compensated speed value is locked and the temperature PID integral is cleared to zero. Simultaneously, a minimum switching interval is set to prevent frequent switching. Compared to existing technologies, this step offers the following advantages: First, by quantifying the fluctuation amplitude and stabilization duration, switching is triggered, ensuring that temperature closed-loop control is only handed over after the pressure has reached a steady state, avoiding premature or late switching. Second, by locking the pressure compensation value and clearing the temperature integral during switching, a smooth and disturbance-free transition from the pressure closed loop to the temperature closed loop is achieved, eliminating sudden speed changes during switching. Third, the minimum switching interval prevents frequent chattering of the state machine near the stability boundary, improving the operational stability of the control system.

[0041] S400: The compressor feedforward speed, pressure compensation speed and temperature compensation speed are superimposed to obtain the compressor demand speed, and the compressor control speed is obtained by using the compressor demand speed as the target and the actual compressor speed as feedback through a speed PID closed loop. In this embodiment, given the obtained compressor feedforward speed, pressure-compensated speed, and temperature-compensated speed, to form a unified multi-source coordinated control architecture and eliminate tracking deviations in the final execution stage, the three speed components need to be algebraically summed to obtain the compressor's required speed. Then, using the required speed as the command target and the actual compressor speed as the feedback quantity, the compressor control speed is output after speed PID closed-loop calculation, directly driving the compressor to operate. The advantages of this step are: first, it unifies the feedforward control quantity, pressure compensation quantity, and temperature compensation quantity into a single required speed command, forming a clear multi-source coordinated control architecture with clear division of labor among the control components; second, it independently tracks and controls the actual compressor speed through speed PID closed-loop, eliminating tracking deviations between the actual speed and the required speed caused by load changes or execution delays, thus improving the control accuracy and response speed of the final execution stage.

[0042] S500: When the difference between the target temperature of the condenser and the actual temperature exceeds the cut-back threshold, the pressure PID closed loop is re-enabled.

[0043] In this embodiment, when the system has switched to temperature PID closed-loop operation and the condenser temperature is stable, if an external disturbance or sudden change in operating conditions causes the actual condenser temperature to deviate from the target temperature, in order to quickly suppress the temperature deviation trend and avoid the temperature deviation from being uncorrectable for a long time, it is necessary to monitor the difference between the target temperature and the actual temperature of the condenser. When the difference exceeds the cut-off threshold, the pressure PID closed-loop is re-enabled. This solves the technical problems of existing dual closed-loop control, which, when encountering external disturbances or sudden changes in operating conditions during the temperature closed-loop operation phase, cannot quickly suppress the continuous deviation of the condenser temperature by relying solely on temperature feedback, lacks a mechanism to actively switch back to pressure control based on the degree of deviation, causes the temperature deviation to be uncorrectable for a long time, and lacks buffer protection, which easily leads to repeated control mode jumps near the disturbance boundary.

[0044] Step S500 in the method provided in this application embodiment includes: The system monitors the difference between the target temperature and the actual temperature of the condenser in real time. When the difference exceeds the cut-off threshold, a cut-off is triggered. During the cut-off, the pressure PID closed loop is re-enabled, the integral term of the temperature PID closed loop is reset to zero, and the temperature PID closed loop is disabled. A detailed explanation follows: In this embodiment, the cut-back threshold refers to the critical temperature deviation value that triggers the temperature closed-loop to cut back to the pressure closed-loop. The cut-back operation is initiated when the difference between the target temperature and the actual temperature of the condenser exceeds this value. This threshold is dynamically calculated rather than a fixed value, and the unit is °C. Re-enabling refers to switching the pressure PID closed-loop from its current inactive state to an active state, causing it to restart calculating the pressure-compensated speed based on the pressure deviation. Resetting the integral term to zero means forcibly clearing the accumulated integral value in the temperature PID closed-loop to zero, so that the temperature PID starts running from its initial state the next time it is enabled. Disabling the temperature PID closed-loop means setting the temperature PID closed-loop to an inactive state, and its output is not involved in speed calculation.

[0045] In this step, firstly, in order to detect abnormal deviations in the system during the temperature closed-loop operation in a timely manner, it is necessary to calculate and continuously monitor the difference between the target temperature and the actual temperature of the condenser in real time. This difference is compared with the cut-off threshold. When the difference exceeds the cut-off threshold, the cut-off operation is triggered. The pressure closed loop can be started immediately for strong correction when the temperature deviation just exceeds the allowable range. For example, when the target temperature is 55℃, the actual temperature drops to 51℃ due to external disturbance, and the difference of 4℃ exceeds the cut-off threshold of 3℃, the cut-off is triggered.

[0046] Furthermore, in order to allow the pressure closed loop to quickly take over control after the switchback, the pressure PID closed loop needs to be re-enabled so that it can recalculate the pressure-compensated speed based on the deviation between the current condenser target pressure and the actual pressure, and quickly suppress further temperature deviation by taking advantage of the fast pressure response.

[0047] Finally, to prevent the historical integral value of the temperature PID closed loop from interfering with the pressure control after the cut-off, the integral term of the temperature PID closed loop needs to be reset to zero and the temperature PID closed loop needs to be disabled. This ensures that the compressor speed during the cut-off period is completely determined by the feedforward speed and the pressure compensation speed, and the temperature PID is in a completely deactivated state.

[0048] Step S500 in the method provided in this application embodiment further includes: A cut-back cooling period is set. After the pressure PID closed loop is re-enabled, switching back to the temperature PID closed loop is prohibited during the cut-back cooling period, so that the pressure PID closed loop has sufficient time to re-establish a stable pressure-compensated speed. A detailed explanation follows: In this embodiment, the back-cut cooling duration refers to the shortest duration for which pressure control is forcibly maintained after the system has switched back to the pressure closed loop. Even if the temperature deviation recovers to below the back-cut threshold within this duration, switching back to the temperature closed loop is not permitted. The unit is seconds (s). Switching back to the temperature PID closed loop refers to the control mode switching operation where the system transitions from the pressure closed loop state to the temperature closed loop state.

[0049] In this step, in order to provide sufficient stabilization time for the pressure PID closed loop and to avoid switching back to the temperature closed loop immediately after the temperature deviation recovers briefly following the switchback to the pressure closed loop, a switchback cooling timer needs to be started after the switchback operation is completed. During this cooling time, the system is forced to maintain the pressure closed loop operation. Even if the switching conditions are met again, the switching operation will not be performed. This can prevent repeated jumps in pressure and temperature modes near the disturbance boundary. For example, if the switchback cooling time is set to 20 seconds, the system will maintain the pressure closed loop operation for 20 seconds after the switchback.

[0050] Step S500 in the method provided in this application embodiment further includes: The deviation between the compressor's current actual speed and the target speed is obtained and denoted as the speed deviation; the rate of change of the condenser's actual temperature is obtained and denoted as the temperature change rate; the deviation between the current ambient temperature and the standard ambient temperature is obtained and denoted as the ambient temperature deviation; based on the weighted sum of the speed deviation, the temperature change rate, and the ambient temperature deviation, a cut-back threshold is calculated. The cut-back threshold is positively correlated with the speed deviation, negatively correlated with the temperature change rate, and positively correlated with the absolute value of the ambient temperature deviation. A detailed explanation follows: In this embodiment, the speed deviation refers to the difference between the actual compressor speed and the current required speed, reflecting the compressor's speed tracking capability, and is measured in r / min. The temperature change rate refers to the amount of change in the actual condenser temperature per unit time, reflecting the severity of temperature change, and is measured in °C / s. The ambient temperature deviation refers to the difference between the current ambient temperature and the standard ambient temperature, reflecting the degree to which the current operating environment deviates from normal operating conditions, and is measured in °C. The weighted sum refers to the value obtained by multiplying the speed deviation, the reciprocal of the temperature change rate, and the absolute value of the ambient temperature deviation by their respective weighting coefficients, and then adding them together; this value serves as the cut-off threshold.

[0051] In this step, to enable the cut-off threshold to adaptively adjust according to the current system operating state, three parameters need to be obtained: speed deviation, temperature change rate, and ambient temperature deviation. When the speed deviation is large, it indicates that the compressor's tracking capability has reached its limit, and the temperature deviation may stem from insufficient execution capability rather than pressure control requirements. The cut-off threshold should be increased to avoid ineffective cut-off. The cut-off threshold is positively correlated with the speed deviation. When the temperature change rate is small, the temperature is rapidly deviating. The cut-off threshold needs to be lowered to allow the system to promptly cut back to the pressure closed loop for rapid correction. The cut-off threshold is negatively correlated with the temperature change rate. When the absolute value of the ambient temperature deviation is large, the system's operating conditions deviate from standard conditions, and the temperature fluctuation tolerance should be relaxed. The cut-off threshold needs to be increased to avoid false cut-offs caused by normal environmental fluctuations. The cut-off threshold is positively correlated with the absolute value of the ambient temperature deviation. By weighting and dynamically calculating the cut-off threshold using these three parameters, adaptive matching between the cut-off sensitivity and the system operating state can be achieved.

[0052] For example, taking the operation of a 3-horsepower air source heat pump in winter heating mode as an example, the system operates stably under temperature closed-loop control. At 50 seconds, the correction coefficient is approximately 0.17, the feedforward speed is approximately 633 r / min, the latching pressure compensation is 120 r / min, the temperature compensation is approximately 60 r / min, and the required speed is approximately 813 r / min. Due to external defrosting, the actual condenser temperature drops to 50℃, a difference of 5℃ from the target temperature of 55℃. The dynamic cut-off threshold is calculated as follows: speed deviation 23 r / min, temperature change rate -0.8℃ / s, ambient temperature deviation 14℃, weighted sum is 23 × 0.02 + 1 / 0.8 × 1.0 + 14 × 0.05 = 2.41℃, rounded down to 2.4℃. If the temperature difference exceeds 2.4℃ by 5℃, a back-loop operation is triggered. The pressure PID is re-enabled, the temperature PID integral is cleared and disabled, the pressure-compensated speed is recalculated and output at 500 r / min, and the required speed is 633 r / min for feedforward plus 500 r / min for pressure compensation, which equals 1133 r / min. The pressure closed-loop operation is maintained within 20 seconds of the back-loop cooling period.

[0053] In summary, this step monitors temperature deviation in real time and triggers a back-off when it exceeds the dynamic back-off threshold. During back-off, the pressure PID closed loop is re-enabled and the temperature PID is reset. A back-off cooling duration is set to prevent repeated mode jumps. The back-off threshold is dynamically calculated using a weighted sum of speed deviation, temperature change rate, and ambient temperature deviation. Compared with existing technologies, this step has the following advantages: First, it actively back-offs to the pressure PID closed loop when the temperature deviation exceeds the limit, utilizing the fast response of pressure to quickly suppress the temperature deviation trend. Second, the temperature PID integral is reset and the temperature closed loop is disabled during back-off, avoiding interference from historical integral values ​​with pressure control. Third, the back-off cooling duration prevents repeated jumps in pressure and temperature modes near disturbance boundaries. Fourth, the back-off threshold is dynamically calculated based on speed deviation, temperature change rate, and ambient temperature deviation, achieving adaptive adjustment of back-off sensitivity. It automatically increases the back-off threshold when the compressor's tracking capability approaches its limit to avoid ineffective back-off, automatically decreases the back-off threshold for early protection when the temperature deviates rapidly, and automatically increases the back-off threshold when environmental conditions deviate from standard conditions to avoid false triggering due to normal fluctuations.

[0054] It should be added that the tuning steps for the control parameters of the pressure PID closed loop include: The proportional, integral, and derivative coefficients of the pressure PID closed loop are encoded as position vectors of particles in three-dimensional space. A particle swarm containing a preset number of particles is initialized, with the position vector of each particle randomly initialized within a preset parameter search range. The fitness value of each particle is calculated using the absolute integral of the pressure deviation between the actual condenser pressure and the target condenser pressure as the fitness value. Based on the fitness value, the individual optimal position of each particle and the global optimal position of the entire particle swarm are determined. The velocity and position of each particle are iteratively updated according to the velocity update formula and position update formula of the particle swarm optimization algorithm. When the number of iterations reaches a preset maximum number of iterations or the fitness value converges to a stable state, the proportional, integral, and derivative coefficients corresponding to the global optimal position are used as the tuning parameters of the pressure PID closed loop. Detailed explanation follows: In this embodiment, the proportional gain coefficient refers to the gain coefficient multiplied by the current pressure deviation in the pressure PID closed loop, determining the controller's response strength to the current deviation. The integral gain coefficient refers to the gain coefficient multiplied by the integral value of the pressure deviation in the pressure PID closed loop, determining the controller's ability to eliminate historical accumulated deviations. The derivative gain coefficient refers to the gain coefficient multiplied by the rate of change of the pressure deviation in the pressure PID closed loop, determining the controller's ability to predict the trend of deviation changes. The particle swarm optimization algorithm is a swarm intelligence optimization algorithm that searches for optimal solutions in a multi-dimensional space by simulating the foraging behavior of bird flocks. Each particle represents a set of candidate solutions and has two attributes: position and velocity. The fitness value is a quantitative index for evaluating the control quality of each set of PID parameters, using the integral of the absolute value of the pressure deviation over time as the evaluation function; a smaller fitness value indicates better control quality. The individual optimal position refers to the position vector where a single particle minimizes its fitness value in the search history, recording the optimal PID parameter combination found by that particle. The global optimal position refers to the position vector where all particles in the entire particle swarm find the minimum fitness value, recording the optimal PID parameter combination found by the swarm.

[0055] For example, an initial particle swarm is constructed with 30 particles. The search space has three dimensions, corresponding to a proportional coefficient search range of 0.5 to 5.0, an integral coefficient search range of 0.01 to 0.5, and a derivative coefficient search range of 0 to 1.0. The initial position of each particle is randomly generated within the search range, and the initial velocity is randomly generated within -0.1 to 0.1 times the search range width. The standard particle swarm velocity-position update formula with an inertia weight of 0.729 and a learning factor of 1.494 is used for iteration. After each iteration, the particle velocity is constrained to within ±1.0 times the maximum velocity, and the particle position is constrained to within the search range. A stochastic gradient descent optimizer is used to fine-tune the particle swarm distribution, with a learning rate of 0.01. The number of iterations is set to 100, and early stopping is triggered when the global optimal fitness value changes by less than 0.1% for 10 consecutive iterations. Finally, the proportional coefficient, integral coefficient, and derivative coefficient corresponding to the global optimal position are output as the tuning parameters for the pressure PID closed loop.

[0056] According to the supplementary content of this step, firstly, by encoding the three parameters of the pressure PID into particle position vectors and presetting the search range, the problems of low efficiency and difficulty in ensuring parameter consistency of manual trial and error tuning are solved; then, by using the absolute value of the pressure deviation integral as the fitness function and performing particle swarm iterative search in the three-dimensional parameter space, the problem of difficulty in balancing the pressure control response speed and overshoot is solved. The tuned parameters can be directly applied to the parameter configuration of the pressure PID closed loop in S200 and S500.

[0057] The embodiments of this application, through the specific implementation methods described above, achieve the following technical effects: This application proposes a heat pump compressor control method based on pressure-temperature dual closed-loop coupling. First, the compressor feedforward speed is calculated based on the ambient temperature and blower speed. Then, during the startup phase, the pressure-compensated speed is calculated using a pressure PID closed-loop. Once the pressure stabilizes, the pressure compensation value is locked, the temperature PID integral is cleared, and the system switches to a temperature PID closed-loop to calculate the temperature-compensated speed. The feedforward speed, pressure-compensated speed, and temperature-compensated speed are superimposed and output as the compressor control speed via a speed PID closed-loop. When the temperature deviation exceeds the dynamic cut-off threshold, the pressure PID closed-loop is re-enabled. This method achieves the control objectives of rapid startup, smooth switching, and abnormal cut-off protection through multi-level coupling of feedforward, pressure, temperature, and speed, along with state machine switching management.

[0058] Example 2, as shown in the appendix Figure 3 As shown, based on the inventive concept of the pressure-temperature dual closed-loop coupling heat pump compressor control method provided in Embodiment 1, this application also provides a pressure-temperature dual closed-loop coupling heat pump compressor control system, specifically including: Feedforward calculation module 11 is used to obtain the ambient temperature, blower speed and condenser target temperature of the heat pump system, and calculate the compressor feedforward speed based on the ambient temperature and the blower speed. Pressure compensation module 12 is used to determine the target pressure of the condenser based on the target temperature of the condenser, collect the actual pressure of the condenser, and calculate the pressure compensation speed through the pressure PID closed loop, wherein the pressure PID closed loop is enabled during the startup phase. The closed-loop switching module 13 is used to collect the actual temperature of the condenser, calculate the temperature compensation speed through the temperature PID closed loop, and lock the current value of the pressure compensation speed and initialize the integral term of the temperature PID closed loop to zero when switching from the pressure PID closed loop to the temperature PID closed loop. The speed closed-loop module 14 is used to superimpose the compressor feedforward speed, pressure compensation speed and temperature compensation speed to obtain the compressor demand speed, and obtain the compressor control speed through speed PID closed-loop with the compressor demand speed as the target and the actual compressor speed as the feedback. The back-off control module 15 is used to re-enable the pressure PID closed loop when the difference between the target temperature of the condenser and the actual temperature exceeds the back-off threshold. The parameter tuning module 16 is used to perform offline tuning of the proportional coefficient, integral coefficient and derivative coefficient of the pressure PID closed loop using the particle swarm optimization algorithm, so as to obtain the tuning parameters of the pressure PID closed loop.

[0059] In one embodiment, the feedforward calculation module 11 is further configured to: input the ambient temperature of the heat pump system and the blower speed into a preset feedforward mapping table, and query the corresponding base speed value; obtain the current running time of the compressor, determine the feedforward correction coefficient based on the running time, wherein the feedforward correction coefficient is negatively correlated with the running time; and multiply the base speed value by the feedforward correction coefficient to obtain the compressor feedforward speed.

[0060] In one embodiment, the pressure compensation module 12 is further configured to: detect a compressor start command; when a start command is detected, set the state of the pressure PID closed loop to active and the state of the temperature PID closed loop to disabled, wherein the temperature PID closed loop does not participate in speed calculation during the disabled period.

[0061] In one embodiment, the closed-loop switching module 13 is further configured to: collect the fluctuation amplitude of the pressure-compensated speed; trigger switching when the fluctuation amplitude is continuously lower than a preset stable threshold for a period of time reaching a stable duration threshold; during switching, latch the output value of the pressure PID closed loop as a constant and keep this constant as the pressure-compensated speed for subsequent superposition calculations; at the switching moment, read the current integral term value of the temperature PID closed loop, force the current integral term value to be set to zero, and start integration from zero to avoid the temperature PID closed loop from generating an output jump at the moment of switching.

[0062] Furthermore, the closed-loop switching module 13 is also used to: set a minimum switching interval duration, and after completing a switch from pressure PID closed loop to temperature PID closed loop, prohibit switching again within the minimum switching interval duration, so as to avoid frequent state machine jitter.

[0063] In one embodiment, the cutback control module 15 is further configured to: monitor the difference between the target temperature of the condenser and the actual temperature in real time; trigger a cutback when the difference exceeds the cutback threshold; during the cutback, re-enable the pressure PID closed loop, reset the integral term of the temperature PID closed loop to zero, and disable the temperature PID closed loop.

[0064] Furthermore, the back-cut control module 15 is also used to: set a back-cut cooling duration, and after re-enabling the pressure PID closed loop, prohibit switching back to the temperature PID closed loop during the back-cut cooling duration, so that the pressure PID closed loop has enough time to re-establish a stable pressure compensation speed.

[0065] Furthermore, the cutback control module 15 is also used to: obtain the deviation between the current actual speed and the target speed of the compressor, denoted as speed deviation; obtain the rate of change of the actual temperature of the condenser, denoted as temperature change rate; obtain the deviation between the current ambient temperature and the standard ambient temperature, denoted as ambient temperature deviation; and calculate a cutback threshold based on the weighted sum of the speed deviation, the rate of change of temperature, and the ambient temperature deviation, wherein the cutback threshold is positively correlated with the speed deviation, negatively correlated with the rate of change of temperature, and positively correlated with the absolute value of the ambient temperature deviation.

[0066] In one embodiment, the parameter tuning module 16 is further configured to: encode the proportional coefficient, integral coefficient, and derivative coefficient of the pressure PID closed loop into position vectors of particles in three-dimensional space; initialize a particle swarm containing a preset number of particles, with the position vector of each particle randomly initialized within a preset parameter search range; calculate the fitness value of each particle using the integral absolute value of the pressure deviation between the actual pressure of the condenser and the target pressure of the condenser as the fitness value; determine the individual optimal position of each particle and the global optimal position of the entire particle swarm based on the fitness value; iteratively update the velocity and position of each particle according to the velocity update formula and position update formula of the particle swarm optimization algorithm; and when the number of iterations reaches a preset maximum number of iterations or the fitness value converges to a stable state, use the proportional coefficient, integral coefficient, and derivative coefficient corresponding to the global optimal position as the tuning parameters of the pressure PID closed loop.

[0067] The pressure-temperature dual-closed-loop coupled heat pump compressor control system provided in this application can achieve intelligent multi-level coupled control management in compressor speed control scenarios of heat pump equipment such as air source heat pumps and ground source heat pumps. This management system encompasses environmental parameter acquisition and feedforward calculation, pressure closed-loop coarse adjustment and temperature closed-loop fine adjustment, and abnormal back-cut protection and speed closed-loop execution. It can be integrated into the heat pump controller or compressor inverter drive board, effectively improving the pressure build-up speed and steady-state temperature control accuracy during startup, reducing the risk of temperature deviation caused by sudden changes in operating conditions or external disturbances. Simultaneously, it provides structured control data support, including feedforward components, pressure compensation components, and temperature compensation components, for system debugging and parameter optimization. For the specific control flow and implementation details of this system, please refer to Embodiment 1.

[0068] It should be noted that the order of the embodiments described above is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. Furthermore, the above description focuses on specific embodiments of this specification. Additionally, the processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired results. In some implementations, multitasking and parallel processing are possible or may be advantageous.

Claims

1. A heat pump compressor control method based on pressure-temperature dual closed-loop coupling, characterized in that, The method includes: The ambient temperature, blower speed and condenser target temperature of the heat pump system are obtained, and the compressor feedforward speed is calculated based on the ambient temperature and the blower speed. The target pressure of the condenser is obtained by looking up a table based on the target temperature of the condenser. The actual pressure of the condenser is collected, and the pressure-compensated speed is calculated by a pressure PID closed loop. The pressure PID closed loop is enabled during the startup phase. The actual temperature of the condenser is collected, and the temperature-compensated speed is calculated through a temperature PID closed loop. When switching from a pressure PID closed loop to a temperature PID closed loop, the current value of the pressure-compensated speed is locked and the integral term of the temperature PID closed loop is initialized to zero. The compressor feedforward speed, pressure compensation speed and temperature compensation speed are superimposed to obtain the compressor demand speed, and the compressor control speed is obtained by using the compressor demand speed as the target and the actual compressor speed as feedback through a speed PID closed loop. When the difference between the target temperature and the actual temperature of the condenser exceeds the cut-off threshold, the pressure PID closed loop is re-enabled.

2. The heat pump compressor control method based on pressure-temperature dual closed-loop coupling according to claim 1, characterized in that, Calculating the compressor feedforward speed based on the ambient temperature and the blower speed includes: Input the ambient temperature and blower speed of the heat pump system into a preset feedforward mapping table to obtain the corresponding base speed value; The current operating time of the compressor is obtained, and a feedforward correction coefficient is determined based on the operating time. The feedforward correction coefficient is negatively correlated with the operating time. Multiplying the base speed value by the feedforward correction coefficient yields the compressor feedforward speed.

3. The heat pump compressor control method based on pressure-temperature dual closed-loop coupling according to claim 1, characterized in that, Enabling the pressure PID closed loop during the startup phase includes: The compressor start command is detected. When the start command is detected, the pressure PID closed loop is set to active and the temperature PID closed loop is set to disabled. The temperature PID closed loop does not participate in speed calculation during the disabled period.

4. The heat pump compressor control method based on pressure-temperature dual closed-loop coupling according to claim 1, characterized in that, When switching from a pressure PID closed loop to a temperature PID closed loop, the current value of the pressure-compensated speed is locked and the integral term of the temperature PID closed loop is initialized to zero, including: The fluctuation range of the pressure-compensated rotation speed is collected, and when the fluctuation range remains below a preset stable threshold for a period of time until a stable duration threshold is reached, a switch is triggered. During switching, the output value of the pressure PID closed loop is latched as a constant, and this constant is used as the pressure-compensated speed for subsequent superposition calculations; At the switching moment, the current integral term value of the temperature PID closed loop is read, and the current integral term value is forcibly set to zero, and integration starts from zero to avoid the output jump of the temperature PID closed loop at the moment of switching.

5. The heat pump compressor control method based on pressure-temperature dual closed-loop coupling according to claim 4, characterized in that, When the fluctuation amplitude remains below a preset stability threshold for an extended period of time, a switching mechanism is triggered, further including: Set a minimum switching interval. After completing a switch from pressure PID closed loop to temperature PID closed loop, the switch shall be prohibited again within the minimum switching interval to avoid frequent state machine chattering.

6. The heat pump compressor control method based on pressure-temperature dual closed-loop coupling according to claim 1, characterized in that, When the difference between the target temperature and the actual temperature of the condenser exceeds the cut-off threshold, the pressure PID closed loop is re-enabled, including: The difference between the target temperature and the actual temperature of the condenser is monitored in real time. When the difference exceeds the cut-back threshold, a cut-back is triggered. During the revert, the pressure PID closed loop is re-enabled, the integral term of the temperature PID closed loop is reset to zero, and the temperature PID closed loop is disabled.

7. The heat pump compressor control method based on pressure-temperature dual closed-loop coupling according to claim 6, characterized in that, When the difference between the target temperature and the actual temperature of the condenser exceeds the cut-off threshold, the pressure PID closed loop is re-enabled, further including: Set a back-cut cooling time. After re-enabling the pressure PID closed loop, prevent switching back to the temperature PID closed loop during the back-cut cooling time, so that the pressure PID closed loop has enough time to re-establish a stable pressure-compensated speed.

8. The heat pump compressor control method based on pressure-temperature dual closed-loop coupling according to claim 6, characterized in that, The calculation steps for the backcut threshold include: Obtain the deviation between the compressor's current actual speed and the target speed, and record it as the speed deviation; Obtain the rate of change of the actual temperature of the condenser, and denot it as the temperature change rate. The deviation between the current ambient temperature and the standard ambient temperature is recorded as the ambient temperature deviation. The cut-back threshold is calculated based on the weighted sum of the rotational speed deviation, the rate of temperature change, and the ambient temperature deviation. The cut-back threshold is positively correlated with the rotational speed deviation, negatively correlated with the rate of temperature change, and positively correlated with the absolute value of the ambient temperature deviation.

9. The heat pump compressor control method based on pressure-temperature dual closed-loop coupling according to claim 1, characterized in that, The tuning steps for the control parameters of the pressure PID closed loop include: The proportional coefficient, integral coefficient, and differential coefficient of the pressure PID closed loop are encoded as the position vector of the particle in three-dimensional space; Initialize a particle swarm containing a preset number of particles, with the position vector of each particle randomly initialized within a preset parameter search range; The fitness value of each particle is calculated by using the absolute value of the integral of the pressure deviation between the actual pressure and the target pressure of the condenser as the fitness value. The individual optimal position of each particle and the global optimal position of the entire particle swarm are determined based on the fitness value. Based on the velocity update formula and position update formula of the particle swarm optimization algorithm, the velocity and position of each particle are iteratively updated; When the number of iterations reaches the preset maximum number of iterations or the fitness value converges to a stable state, the proportional coefficient, integral coefficient, and derivative coefficient corresponding to the global optimal position are used as the tuning parameters of the pressure PID closed loop.

10. A heat pump compressor control system based on pressure-temperature dual closed-loop coupling, characterized in that, The system is used to execute the heat pump compressor control method based on pressure-temperature dual closed-loop coupling as described in any one of claims 1-9, and the system includes: The feedforward calculation module is used to obtain the ambient temperature, blower speed and condenser target temperature of the heat pump system, and calculate the compressor feedforward speed based on the ambient temperature and the blower speed. The pressure compensation module is used to determine the target pressure of the condenser based on the target temperature of the condenser, collect the actual pressure of the condenser, and calculate the pressure compensation speed through the pressure PID closed loop, wherein the pressure PID closed loop is enabled during the startup phase. The closed-loop switching module is used to collect the actual temperature of the condenser, calculate the temperature-compensated speed through the temperature PID closed loop, and lock the current value of the pressure-compensated speed and initialize the integral term of the temperature PID closed loop to zero when switching from the pressure PID closed loop to the temperature PID closed loop. The speed closed-loop module is used to superimpose the compressor feedforward speed, pressure compensation speed and temperature compensation speed to obtain the compressor demand speed, and obtain the compressor control speed through speed PID closed-loop with the compressor demand speed as the target and the actual compressor speed as the feedback. The back-off control module is used to re-enable the pressure PID closed loop when the difference between the target temperature and the actual temperature of the condenser exceeds the back-off threshold. The parameter tuning module is used to perform offline tuning of the proportional coefficient, integral coefficient, and derivative coefficient of the pressure PID closed loop using the particle swarm optimization algorithm, so as to obtain the tuning parameters of the pressure PID closed loop.

Images