Electric compressor fusion control method and device based on CO2 heat pump system

Abstract

The invention discloses a method based on CO 2 The electric compressor fusion control method and device of the heat pump system includes four stages of the compressor adjustment process: the system rapid adjustment stage, the temperature difference PID control takes a large weight, and the pressure difference PID control takes a small weight; the slow adjustment waiting temperature response stage, the pressure difference PID control takes a large weight, and the temperature difference PID control takes a small weight; the precise control stage, the temperature difference PID control takes a large weight, and the pressure difference PID control takes a small weight; the stable stage, the compressor speed PID control amount obtained by only taking the temperature difference between the target temperature and the actual temperature as input is used as the compressor speed control amount in the stable stage. The present invention switches the control target in different control stages according to the characteristics of different control targets, which can effectively reduce the system overshoot in actual control, can quickly stabilize the actual temperature around the target temperature ±1 degree, can quickly stabilize the air outlet temperature of the air conditioner, and improve the driving reliability and comfort.

Description

Technical Field

[0001] The present invention belongs to the technical field of compressor control and particularly relates to a method based on CO 2 A method and device for integrated control of an electric compressor of a heat pump system. Background Art

[0002] Most electric vehicle thermal management systems use heat pump systems, and the electric compressor plays an extremely important role in the entire vehicle control, which is related to the safety of the entire three-electric system. At the same time, the air conditioning system is responsible for regulating the temperature inside the car, which is also directly related to user comfort.

[0003] In C0 2 In the heat pump system, since the temperature and pressure of R744 refrigerant are not proportional, the input of the compressor PID control can be the temperature difference between the target temperature and the actual temperature, or the pressure difference between the optimal exhaust pressure and the actual exhaust pressure of the compressor. Due to the different characteristics between temperature and pressure, the control performance is as follows: when controlled by temperature difference, the temperature response is relatively lagging, the system is prone to overshoot, and the stabilization time is long; when controlled by pressure, the pressure response speed is fast and sensitive, but the system temperature control is not easy to stabilize within plus or minus 1 degree. Summary of the invention

[0004] The purpose of the present invention is to provide a CO-based 2 Electric compressor fusion control method and device for heat pump system to solve CO 2 The problem of temperature control overshoot and failure to stabilize quickly in the heat pump system.

[0005] The technical solution of the present invention is as follows:

[0006] A CO-based 2 The electric compressor fusion control method of the heat pump system includes four stages of the compressor adjustment process: a system fast adjustment stage, a slow adjustment waiting for temperature response stage, a precise control stage, and a stable stage;

[0007] (1) System rapid adjustment stage

[0008] This stage is the initial stage of the system receiving air conditioning requests. At this time, the temperature difference is large, and the compressor speed is adjusted quickly. In this stage, the temperature difference PID control takes a large weight, and the pressure difference PID control takes a small weight:

[0009] PID Out1 =x Weight_Fast ×ΔT 1 +y Weight_Fast ×ΔP 1

[0010] x Wei g ht_Fast>y Weight_Fast >0,x Weight_Fast +y Weight_Fast =1

[0011] In the formula, x Weight_Fast is the temperature difference control weight of the system in the rapid adjustment stage, y Weight_Fast is the pressure difference control quantity weight in the system rapid adjustment stage, ΔT 1 The PID control value of the compressor speed is obtained by taking the temperature difference between the target temperature and the actual temperature as input during the rapid adjustment stage of the system, ΔP 1 The PID control value of the compressor speed is obtained by taking the pressure difference between the optimal exhaust pressure and the actual exhaust pressure of the compressor as input during the rapid adjustment stage of the system. Out1 It is the compressor speed control quantity in the rapid adjustment stage of the system;

[0012] (2) Slow adjustment and waiting for temperature response stage

[0013] When the absolute value of the temperature difference between the target temperature and the actual temperature is reduced to the first threshold, the slow adjustment and waiting for temperature response phase begins; in this phase, the pressure difference PID control takes a large weight, and the temperature difference PID control takes a small weight:

[0014] PID Out2 =x Weight_wait ×ΔT 2 +y Weight_wait ×ΔP 2

[0015] 0<x Weight_wait <y Weight_wait , x Weight_wait +y Weight_wait =1

[0016] In the formula, x Weight_wait is the weight of the temperature difference control quantity in the slow adjustment waiting temperature response stage, y Weight_wait is the pressure difference control weight in the slow adjustment waiting temperature response stage, ΔT 2 The PID control value of the compressor speed is obtained by taking the temperature difference between the target temperature and the actual temperature as input during the slow adjustment waiting temperature response stage, ΔP 2 The PID control value of the compressor speed is obtained by taking the pressure difference between the optimal exhaust pressure and the actual exhaust pressure of the compressor as input during the slow adjustment waiting for temperature response stage. Out2 It is the speed control value of the compressor in the slow adjustment waiting for temperature response stage;

[0017] (3) Precision control stage

[0018] When the absolute value of the temperature difference between the target temperature and the actual temperature is reduced to the second threshold, the fine control stage is entered; the second threshold is less than the first threshold; in this stage, the temperature difference PID control takes a large weight, and the pressure difference PID control takes a small weight:

[0019] PID Out3 =x Weight_fine ×ΔT 3 +y Weight_fine ×ΔP 3

[0020] x Weight_fine >y Weight_fine , x Weight_fine +y Weight_fine =1

[0021] In the formula, x Weight_fine is the weight of the temperature difference control quantity in the fine control stage, y Weight_fine is the pressure difference control weight in the fine control stage, ΔT 3 is the compressor speed PID control quantity obtained by taking the temperature difference between the target temperature and the actual temperature as input in the fine control stage, ΔP 3 The PID control value of the compressor speed is obtained by taking the pressure difference between the optimal exhaust pressure and the actual exhaust pressure of the compressor as input in the fine control stage. Out3 is the compressor speed control value in the fine control stage;

[0022] (4) Stable stage

[0023] In this stage, the compressor speed PID control amount obtained by only taking the temperature difference between the target temperature and the actual temperature as input is used as the compressor speed control amount in the stable stage.

[0024] Furthermore, when the actual temperature reaches the target temperature and remains stable for a specific period of time, it is considered to have entered the stable stage.

[0025] Furthermore, the temperature difference between the target temperature and the actual temperature is used as input to obtain the compressor speed PID control quantity as follows:

[0026] ΔT=(K p_T *(ΔT K -ΔT K-1 )+K i_T *ΔT K +K d_T (ΔT K -2ΔT K-1 -ΔT K-2 ))

[0027] Where ΔT is the compressor speed PID control quantity obtained by taking the temperature difference between the target temperature and the actual temperature as input, K p_T is the temperature difference proportional coefficient, K i_Tis the temperature difference integral coefficient, K d_T is the temperature difference differential coefficient, ΔT K is the temperature difference at the current moment, ΔT K-1 is the temperature difference at the previous moment, ΔT K-2 is the temperature difference at the previous moment.

[0028] Furthermore, the pressure difference between the optimal exhaust pressure and the actual exhaust pressure of the compressor is used as input to obtain the compressor speed PID control quantity as follows:

[0029] ΔP=K p_P *(ΔP K -ΔP K-1 )+K i_P *ΔP K +K d_P (ΔP K -2ΔP K-1 -ΔP K-2 )

[0030] Where ΔP is the compressor speed PID control quantity obtained by taking the pressure difference between the optimal exhaust pressure and the actual exhaust pressure of the compressor as input, K p_P is the pressure difference proportional coefficient, K i_P is the differential pressure integral coefficient, K d_P is the differential pressure coefficient, ΔP K is the pressure difference at the current moment, ΔP K-1 is the pressure difference value at the previous moment, ΔP K-2 is the pressure difference value at the previous moment.

[0031] A CO-based 2 The electric compressor fusion control device of the heat pump system includes four phase modules of the compressor adjustment process: a system fast adjustment phase module, a slow adjustment waiting temperature response phase module, a precision control phase module and a stable phase module;

[0032] The system rapid adjustment stage module corresponds to the initial stage of the system receiving air conditioning requests. At this time, the temperature difference is large, and the compressor speed is adjusted quickly. In this stage, the temperature difference PID control takes a large weight, and the pressure difference PID control takes a small weight:

[0033] PID Out1 =x Weight_Fast ×ΔT 1 +y Weight_Fast ×ΔP 1

[0034] x Wei g ht_Fast >y Weight_Fast >0,x Weight_Fast +y Weight_Fast =1

[0035] In the formula, x Weight_Fast is the temperature difference control weight of the system in the rapid adjustment stage, y Weight_Fast is the pressure difference control quantity weight in the system rapid adjustment stage, ΔT 1 The PID control value of the compressor speed is obtained by taking the temperature difference between the target temperature and the actual temperature as input during the rapid adjustment stage of the system, ΔP 1 The PID control value of the compressor speed is obtained by taking the pressure difference between the optimal exhaust pressure and the actual exhaust pressure of the compressor as input during the rapid adjustment stage of the system. Out1 It is the compressor speed control quantity in the rapid adjustment stage of the system;

[0036] The slow adjustment waiting temperature response phase module is used to enter the slow adjustment waiting temperature response phase when the absolute value of the temperature difference between the target temperature and the actual temperature is reduced to the first threshold; in this phase, the pressure difference PID control takes a large weight, and the temperature difference PID control takes a small weight:

[0037] PID Out2 =x Weight_wait ×ΔT 2 +y Weight_wait ×ΔP 2

[0038] 0<x Weight_wait <y Weight_wait , x Weight_wait +y Weight_wait =1

[0039] In the formula, x Weight_wait is the weight of the temperature difference control quantity in the slow adjustment waiting temperature response stage, y Weight_wait is the pressure difference control weight in the slow adjustment waiting temperature response stage, ΔT 2 The PID control value of the compressor speed is obtained by taking the temperature difference between the target temperature and the actual temperature as input during the slow adjustment waiting temperature response stage, ΔP 2 The PID control value of the compressor speed is obtained by taking the pressure difference between the optimal exhaust pressure and the actual exhaust pressure of the compressor as input during the slow adjustment waiting for temperature response stage. Out2 It is the speed control value of the compressor in the slow adjustment waiting for temperature response stage;

[0040] The module of the fine control stage is used to enter the fine control stage when the absolute value of the temperature difference between the target temperature and the actual temperature is reduced to the second threshold; the second threshold is less than the first threshold; in this stage, the temperature difference PID control takes a large weight, and the pressure difference PID control takes a small weight:

[0041] PID Out3 =x Weight_fine ×ΔT 3 +y Weight_fine ×ΔP 3

[0042] x Weight_fine >y Weight_fine , x Weight_fine +y Weight_fine =1

[0043] In the formula, x Weight_fine is the weight of the temperature difference control quantity in the fine control stage, y Weight_fine is the pressure difference control weight in the fine control stage, ΔT 3 is the compressor speed PID control quantity obtained by taking the temperature difference between the target temperature and the actual temperature as input in the fine control stage, ΔP 3 The PID control value of the compressor speed is obtained by taking the pressure difference between the optimal exhaust pressure and the actual exhaust pressure of the compressor as input in the fine control stage. Out3 is the compressor speed control value in the fine control stage;

[0044] The stable phase module is used to obtain the compressor speed PID control amount using only the temperature difference between the target temperature and the actual temperature as input as the compressor speed control amount in the stable phase.

[0045] Furthermore, when the actual temperature reaches the target temperature and remains stable for a specific period of time, it is considered to have entered the stable stage.

[0046] Furthermore, the temperature difference between the target temperature and the actual temperature is used as input to obtain the compressor speed PID control quantity as follows:

[0047] ΔT=(K p_T *(ΔT K -ΔT K-1 )+K i_T *ΔT K +K d_T (ΔT K -2ΔT K-1 -ΔT K-2 ))

[0048] Where ΔT is the compressor speed PID control quantity obtained by taking the temperature difference between the target temperature and the actual temperature as input, K p_T is the temperature difference proportional coefficient, K i_T is the temperature difference integral coefficient, K d_T is the temperature difference differential coefficient, ΔT K is the temperature difference at the current moment, ΔT K-1 is the temperature difference at the previous moment, ΔT K-2 is the temperature difference at the previous moment.

[0049] Furthermore, the pressure difference between the optimal exhaust pressure and the actual exhaust pressure of the compressor is used as input to obtain the compressor speed PID control quantity as follows:

[0050] ΔP=K p_P *(ΔP K -ΔP K-1 )+K i_P *ΔP K +K d_P (ΔP K -2ΔP K-1 -ΔP K-2 )

[0051] Where ΔP is the compressor speed PID control quantity obtained by taking the pressure difference between the optimal exhaust pressure and the actual exhaust pressure of the compressor as input, K p_P is the pressure difference proportional coefficient, K i_P is the differential pressure integral coefficient, K d_P is the differential pressure coefficient, ΔP K is the pressure difference at the current moment, ΔP K-1 is the pressure difference value at the previous moment, ΔP K-2 is the pressure difference value at the previous moment.

[0052] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0053] The present invention provides a CO-based 2 The electric compressor fusion control method and device of the heat pump system switches the control targets at different control stages according to the characteristics of different control targets, which can effectively reduce system overshoot in actual control, quickly stabilize the actual temperature at around ±1 degree of the target temperature, and quickly stabilize the air outlet temperature of the air conditioner, thereby improving driving reliability and comfort. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 The present invention is based on CO 2 Block diagram of the electric compressor fusion control method for heat pump system. DETAILED DESCRIPTION

[0055] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0056] CO 2 The compressor of the heat pump system uses PID control to control the actual temperature within the range of ±1 degree of the target temperature. However, in actual tests, it is found that there will be a large overshoot after the system responds, resulting in large temperature fluctuations and a long system stabilization time. In order to reduce overshoot and make the system quickly control and stabilize, the present invention is proposed based on CO 2The electric compressor fusion control method and device of the heat pump system can effectively reduce system overshoot in actual control, quickly stabilize the actual temperature at around ±1 degree of the target temperature, quickly stabilize the air outlet temperature of the air conditioner, and improve driving reliability and comfort.

[0057] The present invention is based on CO 2 The electric compressor fusion control method of the heat pump system combines the two control methods to enable the system to respond quickly and stably. The specific control method is as follows: Figure 1 The scheme of the present invention divides the compressor adjustment process into four stages, namely: system fast adjustment stage, slow adjustment waiting temperature response stage, precise control stage and stable stage.

[0058] The two control modes are: compressor speed PID control with the difference between the target temperature and the actual temperature as input, and compressor speed PID control with the difference between the optimal exhaust pressure and the actual exhaust pressure of the compressor as input.

[0059] According to the different characteristics of temperature and pressure, temperature and pressure are used as the weighted control input in different control stages:

[0060] (1) System rapid adjustment stage: This stage is the initial stage of the system receiving air conditioning requests. At this time, the temperature difference is large, and the compressor speed is adjusted rapidly. In this stage, PID control can be mainly performed based on the large temperature difference. The temperature difference PID control takes a large weight, and the pressure difference PID control takes a small weight:

[0061] PID Out1 =x Weight_Fast ×ΔT 1 +y Weight_Fast ×ΔP 1

[0062] x Weight_Fast >y Weight_Fast , x Weight_Fast +y Weight_Fast =1

[0063] In the formula, x Weight_Fast is the temperature difference control weight of the system in the rapid adjustment stage, y Weight_Fast is the pressure difference control quantity weight in the system rapid adjustment stage, ΔT 1 The PID control value of the compressor speed is obtained by taking the temperature difference between the target temperature and the actual temperature as input during the rapid adjustment stage of the system, ΔP 1 The PID control value of the compressor speed is obtained by taking the pressure difference between the optimal exhaust pressure and the actual exhaust pressure of the compressor as input during the rapid adjustment stage of the system. Out1 It is the compressor speed control quantity in the rapid adjustment stage of the system;

[0064] (2) Slow adjustment and waiting for temperature response: When the temperature difference is reduced to a certain value, if the current state continues to be adjusted according to the temperature difference, the compressor capacity will be excessive and the system temperature will overshoot. In this stage, the adjustment can be mainly based on the pressure difference between the optimal exhaust pressure and the actual pressure, waiting for the system temperature response:

[0065] PID Out2 =x Weight_wait ×ΔT 2 +y Weight_wait ×ΔP 2

[0066] x Weight_wait <y Weight_wait , x Weight_wait +y Weight_wait =1

[0067] In the formula, x Weight_wait is the weight of the temperature difference control quantity in the slow adjustment waiting temperature response stage, y Weight_wait is the pressure difference control weight in the slow adjustment waiting temperature response stage, ΔT 2 The PID control value of the compressor speed is obtained by taking the temperature difference between the target temperature and the actual temperature as input during the slow adjustment waiting temperature response stage, ΔP 2 The PID control value of the compressor speed is obtained by taking the pressure difference between the optimal exhaust pressure and the actual exhaust pressure of the compressor as input during the slow adjustment waiting for temperature response stage. Out2 It is the speed control value of the compressor in the slow adjustment waiting for temperature response stage;

[0068] (3) Precision control stage: In this stage, the temperature difference of the system is lower than T Fine_R , the temperature difference can be used as the main adjustment input, and the temperature control is finally stabilized within ±1:

[0069] PID Out3 =x Weight_fine ×ΔT 3 +y Weight_fine ×ΔP 3

[0070] x Weight_fine >y Weight_fine , x Weight_fine +y Weight_fine =1

[0071] In the formula, x Weight_fine is the weight of the temperature difference control quantity in the fine control stage, y Weight_fine is the pressure difference control quantity weight in the fine control stage, ΔT 3 is the compressor speed PID control quantity obtained by taking the temperature difference between the target temperature and the actual temperature as input in the fine control stage, ΔP 3The PID control value of the compressor speed is obtained by taking the pressure difference between the optimal exhaust pressure and the actual exhaust pressure of the compressor as input in the fine control stage. Out3 is the compressor speed control value in the fine control stage;

[0072] (4) Stable phase module: According to the temperature difference control, the weight of the pressure difference is reduced in the process of tending to stability. When the temperature difference between the actual temperature and the target temperature is within a small range and maintained for a certain period of time, it is considered to have entered the stable phase.

[0073] Among them, the temperature difference between the target temperature and the actual temperature is used as input to obtain the compressor speed PID control quantity as follows:

[0074] ΔT=(K p_T *(ΔT K -ΔT K-1 )+K i_T *ΔT K +K d_T (ΔT K -2ΔT K-1 -ΔT K-2 ))

[0075] Where ΔT is the compressor speed PID control quantity obtained by taking the temperature difference between the target temperature and the actual temperature as input, K p_T is the temperature difference proportional coefficient, K i_T is the temperature difference integral coefficient, K d_T is the temperature difference differential coefficient, ΔT K is the temperature difference at the current moment, ΔT K-1 is the temperature difference at the previous moment, ΔT K-2 is the temperature difference at the previous moment.

[0076] The pressure difference between the optimal exhaust pressure and the actual exhaust pressure of the compressor is used as input to obtain the compressor speed PID control quantity as follows:

[0077] ΔP=K p_P *(ΔP K -ΔP K-1 )+K i_P *ΔP K +K d_P (ΔP K -2ΔP K-1 -ΔP K-2 )

[0078] Where ΔP is the compressor speed PID control quantity obtained by taking the pressure difference between the optimal exhaust pressure and the actual exhaust pressure of the compressor as input, K p_P is the pressure difference proportional coefficient, K i_P is the differential pressure integral coefficient, K d_Pis the differential pressure coefficient, ΔP K is the pressure difference at the current moment, ΔP K-1 is the pressure difference value at the previous moment, ΔP K-2 is the pressure difference value at the previous moment.

[0079] The two together are:

[0080] PID Out =X Weight *(K p_T *(ΔT K -ΔT K-1 )+K i_T *ΔT K +K d_T (ΔT K -2ΔT K-1 -ΔT K-2 ))+Y Weight *(K p_P *(ΔP K -ΔP K-1 )+K i_P *ΔP K +K d_P (ΔP K -2ΔP K-1 -ΔP K-2 ))

[0081] Where, X Weight is the temperature difference weight, Y Weight Pressure difference weight.

[0082] The present invention also provides a CO-based 2 The electric compressor fusion control device of the heat pump system includes four phase modules of the compressor adjustment process: a system fast adjustment phase module, a slow adjustment waiting temperature response phase module, a precision control phase module and a stable phase module;

[0083] The system rapid adjustment stage module corresponds to the initial stage of the system receiving air conditioning requests. At this time, the temperature difference is large, and the compressor speed is adjusted quickly. In this stage, the temperature difference PID control takes a large weight, and the pressure difference PID control takes a small weight:

[0084] PID Out1 =x Weight_Fast ×ΔT 1 +y Weight_Fast ×ΔP 1

[0085] x Weight_Fast >y Weight_Fast >0,x Weight_Fast +y Weight_Fast =1

[0086] In the formula, xWeight_Fast is the temperature difference control weight of the system in the rapid adjustment stage, y Weight_Fast is the pressure difference control quantity weight in the system rapid adjustment stage, ΔT 1 The PID control value of the compressor speed is obtained by taking the temperature difference between the target temperature and the actual temperature as input during the rapid adjustment stage of the system, ΔP 1 The PID control value of the compressor speed is obtained by taking the pressure difference between the optimal exhaust pressure and the actual exhaust pressure of the compressor as input during the rapid adjustment stage of the system. Out1 It is the compressor speed control quantity in the rapid adjustment stage of the system;

[0087] The slow adjustment waiting temperature response phase module is used to enter the slow adjustment waiting temperature response phase when the absolute value of the temperature difference between the target temperature and the actual temperature is reduced to the first threshold; in this phase, the pressure difference PID control takes a large weight, and the temperature difference PID control takes a small weight:

[0088] PID Out2 =x Weight_wait ×ΔT 2 +y Weight_wait ×ΔP 2

[0089] 0<x Weight_wait <y Weight_wait , x Weight_wait +y Weight_wait =1

[0090] In the formula, x Weight_wait is the weight of the temperature difference control quantity in the slow adjustment waiting temperature response stage, y Weight_wait is the pressure difference control weight in the slow adjustment waiting temperature response stage, ΔT 2 The PID control value of the compressor speed is obtained by taking the temperature difference between the target temperature and the actual temperature as input during the slow adjustment waiting temperature response stage, ΔP 2 The PID control value of the compressor speed is obtained by taking the pressure difference between the optimal exhaust pressure and the actual exhaust pressure of the compressor as input during the slow adjustment waiting for temperature response stage. Out2 It is the speed control value of the compressor in the slow adjustment waiting for temperature response stage;

[0091] The module of the fine control stage is used to enter the fine control stage when the absolute value of the temperature difference between the target temperature and the actual temperature is reduced to the second threshold; the second threshold is less than the first threshold; in this stage, the temperature difference PID control takes a large weight, and the pressure difference PID control takes a small weight:

[0092] PID Out3 =x Weight_fine ×ΔT 3 +y Weight_fine ×ΔP 3

[0093] x Weight_fine >y Weight_fine , x Weight_fine +y Weight_fine =1

[0094] In the formula, x Weight_fine is the weight of the temperature difference control quantity in the fine control stage, y Weight_fine is the pressure difference control weight in the fine control stage, ΔT 3 is the compressor speed PID control quantity obtained by taking the temperature difference between the target temperature and the actual temperature as input in the fine control stage, ΔP 3 The PID control value of the compressor speed is obtained by taking the pressure difference between the optimal exhaust pressure and the actual exhaust pressure of the compressor as input in the fine control stage. Out3 is the compressor speed control value in the fine control stage;

[0095] The stable phase module is used to obtain the compressor speed PID control amount using only the temperature difference between the target temperature and the actual temperature as input as the compressor speed control amount in the stable phase.

[0096] Furthermore, when the actual temperature reaches the target temperature and remains stable for a specific period of time, it is considered to have entered the stable stage.

[0097] Furthermore, the temperature difference between the target temperature and the actual temperature is used as input to obtain the compressor speed PID control quantity as follows:

[0098] ΔT=(K p_T *(ΔT K -ΔT K-1 )+K i_T *ΔT K +K d_T (ΔT K -2ΔT K-1 -ΔT K-2 ))

[0099] Where ΔT is the compressor speed PID control quantity obtained by taking the temperature difference between the target temperature and the actual temperature as input, K p_T is the temperature difference proportional coefficient, K i_T is the temperature difference integral coefficient, K d_T is the temperature difference differential coefficient, ΔT K is the temperature difference at the current moment, ΔT K-1 is the temperature difference at the previous moment, ΔT K-2 is the temperature difference at the previous moment.

[0100] Furthermore, the pressure difference between the optimal exhaust pressure and the actual exhaust pressure of the compressor is used as input to obtain the compressor speed PID control quantity as follows:

[0101] ΔP=Kp_P *(ΔP K -ΔP K-1 )+K i_P *ΔP K +K d_P (ΔP K -2ΔP K-1 -ΔP K-2 )

[0102] Where ΔP is the compressor speed PID control quantity obtained by taking the pressure difference between the optimal exhaust pressure and the actual exhaust pressure of the compressor as input, K p_P is the pressure difference proportional coefficient, K i_P is the differential pressure integral coefficient, K d_P is the differential pressure coefficient, ΔP K is the pressure difference at the current moment, ΔP K-1 is the pressure difference value at the previous moment, ΔP K-2 is the pressure difference value at the previous moment.

[0103] The technical solution of the present invention is highly practical and has good control effect. The compressor control can meet the comfort of the air-conditioning temperature in the passenger cabin. The positive and negative values ​​of the temperature difference and the pressure difference are considered in Table 1 below, and the upper part of the table is the cooling condition, represented by the label R, and the lower part of the table is the heating condition, represented by the label P.

[0104] Table 1 Heating and cooling conditions

[0105]

[0106] The upper part of the table shows the cooling condition, the system rapid adjustment stage, and the temperature difference ΔT between the target temperature and the actual temperature 1 is a negative value; after turning on the air conditioner, the temperature gradually decreases, and the temperature difference between the target temperature and the actual temperature becomes larger. When it reaches T wait_R (TBD), the system enters the slow adjustment waiting for temperature response stage; the temperature continues to decrease, and when the temperature difference between the target temperature and the actual temperature reaches T Fine_R (TBD), it enters the precision control stage. In order to make the interval continuous, T Fast_R (TBD) and T wait_R Similarly, the lower part of the table is the temperature rising condition, and the temperature is adjusted from right to left.

[0107] To sum up, the present invention intends to solve the problem of the system being unable to quickly stabilize due to overshoot of the control target during the control of the compressor by switching the control target at different control stages according to the characteristics of different control targets (including temperature PID control and pressure difference PID control).

[0108] It should be pointed out that, according to the needs of implementation, the various steps / components described in this application can be split into more steps / components, and two or more steps / components or partial operations of steps / components can be combined into new steps / components to achieve the purpose of the present invention.

[0109] It will be easily understood by those skilled in the art that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A fusion control method for an electric compressor based on a CO2 heat pump system, characterized in that: It includes four stages of the compressor adjustment process: system fast adjustment stage, slow adjustment waiting for temperature response stage, precise control stage and stable stage; (1) System rapid adjustment stage This stage is the initial stage of the system receiving air conditioning requests. At this time, the temperature difference is large, and the compressor speed is adjusted quickly. In this stage, the temperature difference PID control takes a large weight, and the pressure difference PID control takes a small weight: PID Out1 =x Weight_Fast ×ΔT1+y Weight_Fast ×ΔP1 x Weight_Fast >and Weight_Fast >0,x Weight_Fast +y Weight_Fast =1 In the formula, x Weight_Fast is the temperature difference control weight of the system in the rapid adjustment stage, y Weight_Fast is the pressure difference control quantity weight in the rapid adjustment stage of the system, ΔT1 is the compressor speed PID control quantity obtained by taking the temperature difference between the target temperature and the actual temperature as input in the rapid adjustment stage of the system, ΔP1 is the compressor speed PID control quantity obtained by taking the pressure difference between the optimal exhaust pressure and the actual exhaust pressure of the compressor as input in the rapid adjustment stage of the system, PID Out1 It is the compressor speed control quantity in the rapid adjustment stage of the system; (2) Slow adjustment and waiting for temperature response stage When the absolute value of the temperature difference between the target temperature and the actual temperature is reduced to the first threshold, the slow adjustment and waiting for temperature response phase begins; in this phase, the pressure difference PID control takes a large weight, and the temperature difference PID control takes a small weight: PID Out2 =x Weight_wait ×ΔT2+y Weight_wait ×ΔP2 0<x Weight_wait and Weight_wait ,x Weight_wait +y Weight_wait =1 In the formula, x Weight_wait is the weight of the temperature difference control quantity in the slow adjustment waiting temperature response stage, y Weight_wait is the weight of the pressure difference control quantity in the slow adjustment waiting temperature response stage, ΔT2 is the compressor speed PID control quantity obtained by taking the temperature difference between the target temperature and the actual temperature as input in the slow adjustment waiting temperature response stage, ΔP2 is the compressor speed PID control quantity obtained by taking the pressure difference between the optimal exhaust pressure and the actual exhaust pressure of the compressor as input in the slow adjustment waiting temperature response stage, PID Out2 It is the speed control value of the compressor in the slow adjustment waiting for temperature response stage; (3) Precision control stage When the absolute value of the temperature difference between the target temperature and the actual temperature is reduced to the second threshold, the fine control stage is entered; the second threshold is less than the first threshold; in this stage, the temperature difference PID control takes a large weight, and the pressure difference PID control takes a small weight: PID Out3 =x Weight_fine ×ΔT3+y Weight_fine ×ΔP3 x Weight_fine >and Weight_fine ,x Weight_fine +y Weight_fine =1 In the formula, x Weight_fine is the weight of the temperature difference control quantity in the fine control stage, y Weight_fine is the weight of the pressure difference control quantity in the fine control stage, ΔT3 is the compressor speed PID control quantity obtained by taking the temperature difference between the target temperature and the actual temperature as input in the fine control stage, ΔP3 is the compressor speed PID control quantity obtained by taking the pressure difference between the optimal exhaust pressure and the actual exhaust pressure of the compressor as input in the fine control stage, PID Out3 is the compressor speed control value in the fine control stage; (4) Stable stage In this stage, the compressor speed PID control amount obtained by only taking the temperature difference between the target temperature and the actual temperature as input is used as the compressor speed control amount in the stable stage.

2. The electric compressor fusion control method based on the CO2 heat pump system according to claim 1 is characterized in that: When the actual temperature reaches the target temperature and remains stable for a certain period of time, it is considered to have entered the stable stage.

3. The electric compressor fusion control method based on the CO2 heat pump system according to claim 1 or 2, characterized in that: The temperature difference between the target temperature and the actual temperature is used as input to obtain the compressor speed PID control quantity as follows: ΔT=(K p_T *(ΔT K -ΔT K-1 )+K i_T *ΔT K +K d_T (ΔT K -2ΔT K-1 -ΔT K-2 )) Where ΔT is the compressor speed PID control quantity obtained by taking the temperature difference between the target temperature and the actual temperature as input, K p_T is the temperature difference proportional coefficient, K i_T is the temperature difference integral coefficient, K d_T is the temperature difference differential coefficient, ΔT K is the temperature difference at the current moment, ΔT K-1 is the temperature difference at the previous moment, ΔT K-2 is the temperature difference at the previous moment.

4. The electric compressor fusion control method based on the CO2 heat pump system according to claim 1 or 2, characterized in that: The pressure difference between the optimal exhaust pressure and the actual exhaust pressure of the compressor is used as input to obtain the compressor speed PID control quantity as follows: ΔP=K p_P *(ΔP K -ΔP K-1 )+K i_P *ΔP K +K d_P (ΔP K -2ΔP K-1 -ΔP K-2 ) Where ΔP is the compressor speed PID control quantity obtained by taking the pressure difference between the optimal exhaust pressure and the actual exhaust pressure of the compressor as input, K p_P is the pressure difference proportional coefficient, K i_P is the differential pressure integral coefficient, K d_P is the differential pressure coefficient, ΔP K is the pressure difference at the current moment, ΔP K-1 is the pressure difference value at the previous moment, ΔP K-2 is the pressure difference value at the previous moment.

5. An electric compressor fusion control device based on a CO2 heat pump system, characterized in that: It includes four phase modules of the compressor adjustment process: system fast adjustment phase module, slow adjustment waiting temperature response phase module, precise control phase module and stable phase module; The system rapid adjustment stage module corresponds to the initial stage of the system receiving air conditioning requests. At this time, the temperature difference is large, and the compressor speed is adjusted quickly. In this stage, the temperature difference PID control takes a large weight, and the pressure difference PID control takes a small weight: PID Out1 =x Weight_Fast ×ΔT1+y Weight_Fast ×ΔP1 x Weight_Fast >and Weight_Fast >0,x Weight_Fast +y Weight_Fast =1 In the formula, x Weight_Fast is the temperature difference control weight of the system in the rapid adjustment stage, y Weight_Fast is the pressure difference control quantity weight in the rapid adjustment stage of the system, ΔT1 is the compressor speed PID control quantity obtained by taking the temperature difference between the target temperature and the actual temperature as input in the rapid adjustment stage of the system, ΔP1 is the compressor speed PID control quantity obtained by taking the pressure difference between the optimal exhaust pressure and the actual exhaust pressure of the compressor as input in the rapid adjustment stage of the system, PID Out1 It is the compressor speed control quantity in the rapid adjustment stage of the system; The slow adjustment waiting temperature response phase module is used to enter the slow adjustment waiting temperature response phase when the absolute value of the temperature difference between the target temperature and the actual temperature is reduced to the first threshold; in this phase, the pressure difference PID control takes a large weight, and the temperature difference PID control takes a small weight: PID Out2 =x Weight_wait ×ΔT2+y Weight_wait ×ΔP2 0<x Weight_wait and Weight_wait ,x Weight_wait +y Weight_wait =1 In the formula, x Weight_wait is the weight of the temperature difference control quantity in the slow adjustment waiting temperature response stage, y Weight_wait is the weight of the pressure difference control quantity in the slow adjustment waiting temperature response stage, ΔT2 is the compressor speed PID control quantity obtained by taking the temperature difference between the target temperature and the actual temperature as input in the slow adjustment waiting temperature response stage, ΔP2 is the compressor speed PID control quantity obtained by taking the pressure difference between the optimal exhaust pressure and the actual exhaust pressure of the compressor as input in the slow adjustment waiting temperature response stage, PID Out2 It is the speed control value of the compressor in the slow adjustment waiting for temperature response stage; The module of the fine control stage is used to enter the fine control stage when the absolute value of the temperature difference between the target temperature and the actual temperature is reduced to the second threshold; the second threshold is less than the first threshold; in this stage, the temperature difference PID control takes a large weight, and the pressure difference PID control takes a small weight: PID Out3 =x Weight_fine ×ΔT3+y Weight_fine ×ΔP3 x Weight_fine >and Weight_fine ,x Weight_fine +y Weight_fine =1 In the formula, x Weight_fine is the weight of the temperature difference control quantity in the fine control stage, y Weight_fine is the weight of the pressure difference control quantity in the fine control stage, ΔT3 is the compressor speed PID control quantity obtained by taking the temperature difference between the target temperature and the actual temperature as input in the fine control stage, ΔP3 is the compressor speed PID control quantity obtained by taking the pressure difference between the optimal exhaust pressure and the actual exhaust pressure of the compressor as input in the fine control stage, PID Out3 is the compressor speed control value in the fine control stage; The stable phase module is used to obtain the compressor speed PID control amount using only the temperature difference between the target temperature and the actual temperature as input as the compressor speed control amount in the stable phase.

6. The electric compressor fusion control device based on the CO2 heat pump system according to claim 5 is characterized in that: When the actual temperature reaches the target temperature and remains stable for a certain period of time, it is considered to have entered the stable stage.

7. The electric compressor fusion control device based on the CO2 heat pump system according to claim 5 or 6, characterized in that: The temperature difference between the target temperature and the actual temperature is used as input to obtain the compressor speed PID control quantity as follows: ΔT=(K p_T *(ΔT K -ΔT K-1 )+K i_T *ΔT K +K d_T (ΔT K -2ΔT K-1 -ΔT K-2 )) Where ΔT is the compressor speed PID control quantity obtained by taking the temperature difference between the target temperature and the actual temperature as input, K p_T is the temperature difference proportional coefficient, K i_T is the temperature difference integral coefficient, K d_T is the temperature difference differential coefficient, ΔT K is the temperature difference at the current moment, ΔT K-1 is the temperature difference at the previous moment, ΔT K-2 is the temperature difference at the previous moment.

8. The electric compressor fusion control device based on the CO2 heat pump system according to claim 5 or 6, characterized in that: The pressure difference between the optimal exhaust pressure and the actual exhaust pressure of the compressor is used as input to obtain the compressor speed PID control quantity as follows: ΔP=K p_P *(ΔP K -ΔP K-1 )+K i_P *ΔP K +K d_P (ΔP K -2ΔP K-1 -ΔP K-2 ) Where ΔP is the compressor speed PID control quantity obtained by taking the pressure difference between the optimal exhaust pressure and the actual exhaust pressure of the compressor as input, K p_P is the pressure difference proportional coefficient, K i_P is the differential pressure integral coefficient, K d_P is the differential pressure coefficient, ΔP K is the pressure difference at the current moment, ΔP K-1 is the pressure difference value at the previous moment, ΔP K-2 is the pressure difference value at the previous moment.

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