A multi-state machine switching control method based on hot gas bypass and heat pump mode

Abstract

The application discloses a kind of based on the switching control method of multiple state machines of hot gas bypass and heat pump mode, the switching control method includes the following steps: starting air conditioning system, based on the switching condition of hot gas bypass state machine and heat pump state machine, air conditioning system is switched to corresponding state machine and is operated;The state machine of operation first enters initialization state, and whether to meet waiting state jump condition is judged, if meeting, state machine jumps into waiting state, otherwise, whether to meet pre-starting condition is further judged, if meeting, state machine enters pre-starting state, otherwise, keep initialization state and run;The application is designed in hot gas bypass mode state machine and heat pump mode state machine by waiting state, make hot gas bypass state machine and heat pump state machine link when running, avoid unnecessary compressor shutdown in air conditioning system, can make two state machines switch naturally, improve passenger comfort, and avoid a part of loss on energy consumption.

Description

Technical Field

[0001] This invention relates to the field of automotive thermal management technology, and in particular to a multi-state machine switching and control method based on hot gas bypass and heat pump mode. Background Technology

[0002] With the rapid popularization of new energy vehicles, car consumers have increasingly higher requirements for passenger cabin comfort. How to improve passenger comfort while balancing energy consumption places higher demands on the vehicle's thermal management system. Currently, some models on the market adopt a thermal management solution of "cooling and dehumidification + heat pump + hot gas bypass." For example, at high temperatures (e.g., ambient temperature above 5℃), cooling and dehumidification mode is used; at medium and low ambient temperatures (e.g., ambient temperature -10~5℃), heat pump mode is used; and at extremely low ambient temperatures (e.g., ambient temperature below -10℃), hot gas bypass mode is used. During the use of a car's air conditioning system, the operating mode switches between cooling & dehumidification, heat pump, and hot gas bypass modes as the ambient temperature changes. In most models, the compressor stops during the switching between heat pump and hot gas bypass modes, waiting for system conditions to be met, such as refrigerant pressure balance or valve opening to be correct, before switching to the other mode. Based on experience, this time usually takes more than 10 seconds. This strategy firstly causes system vibration, with the compressor starting and stopping noticeably noticeable to passengers; secondly, it causes changes in the air outlet temperature, reducing passenger heating comfort; and finally, the frequent starting and stopping of the compressor also leads to unnecessary increases in energy consumption. Summary of the Invention

[0003] The present invention aims to provide a multi-state machine switching and control method based on hot gas bypass and heat pump modes, including a hot gas bypass state machine and a heat pump state machine. The multi-state machine switching and control method includes the following steps:

[0004] S1. Turn on the air conditioning system and switch the air conditioning system to the corresponding state machine for operation based on the switching conditions of the hot gas bypass state machine and the heat pump state machine.

[0005] S2. The running state machine first enters the initialization state and determines whether the waiting state transition condition is met. If it is met, the state machine transitions to the waiting state. Otherwise, it further determines whether the pre-start condition is met. If it is met, the state machine enters the pre-start state. Otherwise, it remains in the initialization state.

[0006] S3. After the current state machine jumps into the waiting state, it will determine whether the running state conditions are met. If they are met, it will control the current state machine to enter the running state to control the air conditioning system to run. Otherwise, it will further determine whether the switching conditions of other state machines are met. If they are met, the air conditioning system will be switched to the corresponding state machine to run. Otherwise, the original state machine will re-enter the initialization state to realize the switching and control between multiple state machines.

[0007] Preferably, in step S1, the switching condition for the hot gas bypass state machine is that the ambient temperature is less than a preset value one, and the switching condition for the heat pump state machine is that the ambient temperature is less than a preset value two, and the preset value one < the preset value two.

[0008] Preferably, in step S2, after the heat pump state machine enters the pre-start state, it will again determine whether the air conditioning system still meets the operating conditions of the current state machine. If it does, the heat pump state machine will be controlled to enter the operating state after a preset time. Otherwise, it will return to the initialization state.

[0009] Preferably, the pre-start conditions for the hot gas bypass state machine to enter the pre-start state in step S2 include condition one and condition two, with condition one having a higher priority than condition two. The determination of the hot gas bypass state machine entering the pre-start state includes the following sub-steps:

[0010] S21. Determine whether the air conditioning system meets condition one. If it does, the hot gas bypass state machine will enter the dwell state from the initial state; otherwise, maintain the initial state.

[0011] S22. When the hot gas bypass state machine enters the dwell state, it will further determine whether condition two is met. If it is met, it will enter the pre-start state; otherwise, it will maintain the dwell state.

[0012] Preferably, the first condition for the hot gas bypass state machine to enter the pre-start state is whether the air conditioning system meets the switching conditions of the hot gas bypass state machine, and the second condition for the hot gas bypass state machine to enter the pre-start state is that the high pressure and low pressure of the air conditioning system reach the balance threshold and the hot gas bypass state machine is fault-free.

[0013] Preferably, after the hot gas bypass state machine enters the pre-start state in step S2, the following sub-steps are included:

[0014] A1. Determine whether the air conditioning system still meets the current operating conditions of the state machine. If it does, control the hot gas bypass state machine to enter the pressure build-up state after a preset time of two.

[0015] A2. After the hot gas bypass state machine enters the pressure building state, it controls the air conditioning system to build up pressure and makes a judgment based on the pressure building conditions. If the air conditioning system meets the pressure building conditions, the current state machine enters the running state to control the air conditioning system to run; otherwise, it enters the shutdown state to control the air conditioning system to shut down.

[0016] A3. After the air conditioning system enters the shutdown state in step A2 above, the current state machine will enter the pressure balance state after a preset time of three to balance the high and low pressures in the air conditioning system. After a preset time of four, it will enter the pressure flushing state from the pressure balance state to perform flushing treatment. After flushing treatment, it will re-enter the pressure building state from the pressure building state after a preset time of five to cycle through the pressure building process until the air conditioning system meets the pressure building conditions and enters the operating state.

[0017] Preferably, the pre-start state, pressure build-up state, running state, shutdown state, pressure balance state, and pressurization state in the hot gas bypass state machine constitute the parent node of the hot gas bypass state machine. When the hot gas bypass state machine does not meet the running state conditions, it can directly enter the shutdown state from any state in the parent node.

[0018] Preferably, after the air conditioning system enters the shutdown state in step A1, the current state machine will enter the pressure balance state after a preset time of three. Then, it is determined whether the air conditioning system meets the delay condition or the pressure condition. If it does not meet either condition, it is further determined whether the current state machine switching condition is met. If it does not meet the condition, it enters the initialization state; otherwise, it enters the standby state to control the air conditioning system to shut down.

[0019] Preferably, the hot gas bypass state machine transitions from the waiting state to the running state via the following sub-steps:

[0020] S31. Determine whether the air conditioning system still meets the current state conditions of the state machine. If it does, proceed with the flushing process from the waiting state.

[0021] S32. After flushing, the system transitions from the pressurizing state to the pressure-building state after a preset time of five. The pressure-building process is repeated until the air conditioning system meets the pressure-building conditions and enters the operating state, thus controlling the operation of the air conditioning system.

[0022] The beneficial effects of this invention are:

[0023] 1. This invention designs waiting states in the hot gas bypass mode state machine and the heat pump mode state machine, so that the hot gas bypass mode state machine and the heat pump mode state machine can be linked during operation, avoiding unnecessary compressor shutdowns in the air conditioning system. This allows the two state machines to switch naturally, improving passenger comfort and avoiding some energy loss.

[0024] 2. By establishing a parent node such as a "non-protection node", the state machine can enter a shutdown state within one program cycle when conditions such as "the current system conditions do not meet the requirements to maintain the hot gas bypass mode, such as the ambient temperature of the air conditioning system rising to the heat pump mode operating range; or the current thermal management system actuator has a fault, such as a compressor fault" are met, thus achieving the effect of timely protection. Attached Figure Description

[0025] Figure 1 This is a flowchart illustrating the switching between multiple state machines in an embodiment of the present invention.

[0026] Figure 2 This is a flowchart illustrating the operation of the heat pump state machine in an embodiment of the present invention.

[0027] Figure 3 This is a flowchart of the hot gas bypass state machine operation in an embodiment of the present invention. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Please see Figures 1 to 3 This invention provides a multi-state machine switching control method based on hot gas bypass and heat pump modes. The system scheme includes three modes: cooling and dehumidification mode, heat pump mode, and hot gas bypass mode. Each operating mode corresponds to its own state machine. After the air conditioning system is turned on, the program will judge the current system environment and the switching conditions of each state machine, including but not limited to ambient temperature, and jump to the set corresponding mode.

[0030] When the air conditioning system is on, the program will switch between cooling / dehumidification mode, heat pump mode, and hot air bypass mode according to changes in the current system environment, including but not limited to changes in ambient temperature.

[0031] Air conditioning systems have their own operating states for different operating modes.

[0032] The heat pump mode states include: initialization state 1, pre-start state 1, waiting state 1, and running state 1.

[0033] The hot gas bypass mode states include: initialization state 2, pressure balance state, shutdown state, pre-start state 2, pressure build-up state, flushing state, dwell state, waiting state 2, and running state 2.

[0034] When the air conditioner is off, the state machines of all three modes are in the off state. After the air conditioner is turned on, the program can only run in one of the modes, and the other modes are in the off state. For example, when the air conditioner is running in heat pump mode, the states of heat pump mode can jump to each other, but the state machines of cooling and dehumidification mode and hot air bypass mode are in the initialization state. Figure 1 The overall process of switching between the three modes of the air conditioning system is briefly summarized.

[0035] The heat pump state machine executes the following logic (e.g.) Figure 2 (as shown)

[0036] When the air conditioner is turned on, and the system environment meets the requirements, including but not limited to ambient temperature conditions, it enters heat pump mode.

[0037] Among them, initialization state 1, waiting state 1, pre-start state 1, and running state 1 are the jump nodes of the heat pump state machine mode. In each node, the current state machine will assign a value to the air conditioning system state so as to control the air conditioning system to enter the corresponding state operation.

[0038] The heat pump mode first enters the initialization state one node. In initialization state one, "system status = off" ("=" is the assignment operator, equivalent to updating the air conditioning system status to off, the same below). Initialization state one corresponds to two jump methods:

[0039] Jump Method 1: Determine if the system meets the waiting state jump condition, i.e., "current mode == hot gas bypass mode" (the current mode can be determined based on a global variable in the state machine program; "==" is the operator to determine whether the left and right sides are equal, i.e., whether the current mode is in hot gas bypass mode, the same below). If the waiting state jump condition is true, the current state machine jumps to the waiting state, in which "system state = off".

[0040] The second jump method involves determining whether the system environment meets the pre-start conditions of the current state machine. Specifically, if the system is currently in an air conditioning off state or a cooling / dehumidifying mode, and the system ambient temperature and other conditions meet the requirements for transitioning to heat pump mode, then the current state machine jumps from initialization state one to pre-start state one. In pre-start state one, "system state = pre-start state". If neither the waiting state jump condition nor the pre-start condition is met, then the current state is maintained. Figure 2 The numbers 1 and 2 in the jump direction indicate the priority of the jump between states, with number 1 having a higher priority than number 2, and so on.

[0041] In practical applications, if the air conditioning system is currently operating in cooling / dehumidification mode, the heat pump state machine will remain at the initialization state one node, waiting for the air conditioning system environment to meet the pre-start conditions of the heat pump state machine. This includes, but is not limited to, a decrease in ambient temperature, increased heating demand, and the system being unable to operate stably in cooling / dehumidification mode (evaporator temperature protection, etc.). Therefore, it needs to enter heat pump mode, and the heat pump mode state machine node will jump from initialization state one to pre-start state one. Jumping to the pre-start state one node is to allow actuators such as the expansion valve to move to the appropriate positions, preparing for the compressor to start in the first stage of operation (if the compressor starts before the expansion valve and other actuators are open, it may cause damage to the system). If the air conditioning system is currently operating in hot gas bypass mode, the heat pump state machine will jump to the waiting state one node, waiting for the heat pump state machine switching conditions to be met, including, but not limited to, an increase in ambient temperature, and the system being unable to operate stably in hot gas bypass mode. Therefore, it needs to enter heat pump mode. At this time, the expansion valve and other actuators are already in the open state, so the heat pump mode state machine node can jump directly from the waiting state one to the operating state one, avoiding compressor shutdown waiting time.

[0042] For the heat pump state machine pre-start state one node, firstly determine whether the current mode of the air conditioning system is still in heat pump mode. If the system environment conditions are not met, resulting in "current mode ~= heat pump mode", then jump back to initialization state one. Secondly, if the current system environment conditions are met and the system remains in heat pump mode, then after a period of time (i.e., preset time one), such as 10 seconds (during which the actuators of the air conditioning system will have corresponding actions, such as the expansion valve and other actuators will move to the corresponding positions), the heat pump mode state machine node will jump from pre-start state one to running state one, in which "system state = running".

[0043] For the heat pump state machine in waiting state one node, first determine whether the system environment meets the switching conditions of the heat pump state machine (i.e., causing the system to switch from hot gas bypass mode to heat pump mode). If it does, the heat pump state machine directly switches from waiting state one to running state one. Secondly, if it switches from hot gas bypass mode to cooling and dehumidification or turns off the air conditioner at this time, the heat pump state machine will switch back to initialization state one, and the heat pump state machine will be in the off state.

[0044] For the heat pump state machine, state one is the stable operating state of heat pump mode. If the air conditioning system does not meet the switching conditions of the current state machine, resulting in "current mode ~= heat pump mode", then the current state machine jumps to initialization state one.

[0045] When the compressor is in the off or pre-start state in heat pump mode, it is prohibited from starting and its speed is 0.

[0046] The hot gas bypass state machine executes the following logic (e.g.) Figure 3 (as shown)

[0047] When the air conditioner is turned on, if the system environment (including but not limited to ambient temperature) meets the switching conditions of the hot gas bypass state machine, the air conditioning system will enter the hot gas bypass mode.

[0048] The initialization state 2, waiting state 2, dwell state, pressure balance state, shutdown state, pre-start state 2, pressure build-up state, operating state 2, and flushing state are the jump nodes of the hot gas bypass state machine. Each node assigns a value to the state of the air conditioning system. The non-protected node (SVIHP) is a parent node of the hot gas bypass mode state machine, which includes child nodes such as pressure balance state, shutdown state, pre-start state 2, pressure build-up state, operating state 2, and flushing state. The non-protected node (SVIHP) parent node starts execution from pre-start state 2. The establishment of the "non-protected node" parent node is mainly to ensure that when conditions such as "the current system conditions do not meet the requirements for maintaining hot gas bypass mode, such as the air conditioning system ambient temperature rising to the heat pump mode operating range; or the current thermal management system actuator has a fault, such as a compressor fault" are met, the state machine can enter the shutdown state within one program cycle, achieving a timely protection effect.

[0049] The hot gas bypass state machine starts at initialization state two, where "system state = off". In the off state, the actuators related to the thermal management system are not controlled by the hot gas bypass mode logic. If the system meets the waiting state transition condition ("current mode == heat pump mode"), it transitions to waiting state two, where "system state = off". Secondly, if the system's current mode is either the air conditioning system off state or cooling / dehumidification mode, and the ambient temperature and other conditions meet condition one of the pre-start conditions for transitioning to the hot gas bypass mode, then it transitions from initialization state two to the idle state. Otherwise, the hot gas bypass mode state machine will remain at the initialization state two node.

[0050] When the system mode switches from the air conditioning system off state or cooling / dehumidification mode to hot gas bypass mode, the current state machine switches to the idle state. If the system meets condition two in the pre-start conditions, that is, the high pressure and low pressure of the system reach the balance threshold (the balance threshold is usually between 0-6 bar, which varies depending on the thermal management system), such as |high pressure - low pressure| < 2 bar (bar is a unit of air pressure, equivalent to one atmosphere), and the current thermal management system actuators are not faulty, such as the compressor, then the current state machine switches to pre-start state two. In pre-start state two, "system state = pre-start state". Under pre-start state two, the thermal management system actuators will have corresponding actions, such as the expansion valve and other actuators will move to the preset position.

[0051] After waiting for a period of time in pre-start state two (preset time two), such as 20 seconds, it will jump to pressure building state. In pressure building state, "system state = pressure building" and the compressor will start running to increase the high and low pressure of the system.

[0052] If the system's high and low pressures reach the target thresholds (pressure build-up conditions, and the target thresholds are usually between 3 and 30 bar, depending on the thermal management system), such as high pressure > 9 bar and low pressure > 4 bar, then pressure build-up is successful; otherwise, if the target high and low pressure thresholds are not reached within 30 seconds, then pressure build-up fails.

[0053] When pressure build-up is successful, the system transitions from node pressure build-up to operating state two, where "system state = operating". The operating mode is a sign of stable operation in the hot gas bypass mode. The actuators of the thermal management system will perform corresponding closed-loop control to maintain stable system operation.

[0054] When pressure build-up fails, the system will jump to the shutdown state, "System State = Shutdown". In the shutdown state, the compressor stops running. After a delay (preset time three), such as 10 seconds, it will jump from the shutdown state to the pressure balance state to balance the high and low pressure in the air conditioning system, "System State = Pressure Balance". In this state, the compressor still runs at 0 speed.

[0055] After a further delay (preset time four), such as 20 seconds, the state machine jumps to the flushing state, "system state = flushing". In the flushing state, the compressor starts to run, and actuators such as the electronic expansion valve will move to the designated position to further make the refrigerant more evenly distributed in the system.

[0056] After the compressor runs continuously for a period of time (segment five), such as 60 seconds, it returns from the flushing state to the pressure-building state.

[0057] If, in any child node of the SVIHP parent node, the current system conditions do not meet the requirements for maintaining the hot gas bypass mode (e.g., ambient temperature rises to the heat pump mode operating range, or there is a fault in the current thermal management system actuator, such as a compressor fault), then the system will directly jump to the shutdown state from any child node of the parent node. After a delay (preset time three), such as 10 seconds, it will jump to the pressure balance state. In the pressure balance state, if the delay condition is met, such as a delay of 20 seconds, or if the system high pressure and low pressure reach the balance threshold (e.g., |high pressure - low pressure| < 2 bar), then the system will jump to the shutdown state, which is the paused state node. If the current mode does not meet the requirements for maintaining the hot gas bypass mode, then the system will jump back to the initialization state state two node. If the current mode is still in the hot gas bypass mode, then the system must wait for the thermal management system actuator fault to be resolved before it can jump back to the pre-start state state two.

[0058] If the current system mode is heat pump mode, and the system environment (including but not limited to ambient temperature conditions) meets the requirements for entering hot gas bypass mode, the hot gas bypass mode state machine directly jumps from the waiting state node 2 to the flushing state node, and enters the pressure build-up state after a delay (preset time 5).

[0059] The compressor is prohibited from starting when the system is in the initialization state, pre-start state, shutdown state, or pressure balance state, and the speed is 0 in all of these states.

[0060] The linkage between the state machine in heat pump mode and the state machine in hot gas bypass mode;

[0061] The heat pump state machine and the hot gas bypass state machine are linked through the "waiting state one" and "waiting state two" nodes.

[0062] If the air conditioner is on and currently operating in heat pump mode, the hot gas bypass mode state machine will jump from initialization state two to waiting state two and wait at this node. Once the ambient temperature drops below a threshold, such as -10℃, meeting the requirements for entering hot gas bypass mode, the hot gas bypass mode state machine will directly jump from waiting state two to the flushing state node. In the flushing state, the compressor can run, and after running for a period of time, it jumps to the pressure build-up state. Otherwise, if the state machine for entering hot gas bypass mode is executed according to the cooling / dehumidification mode, it will first enter the pre-start state two node. In the pre-start state, the compressor will stop and wait at 0 speed for a period of time (preset time five), such as 20 seconds, before entering the pressure build-up state. Therefore, the existence of the waiting state two node prevents the system from entering the pre-start state, thus avoiding unnecessary compressor shutdown.

[0063] If the air conditioner is turned on and currently operating in hot bypass mode, the heat pump state machine will jump from initialization state one to waiting state one and wait at this node. Once the ambient temperature rises above a threshold, such as -10℃, meeting the requirements for entering heat pump mode, the "heat pump mode state machine" will directly jump from waiting state one to running state one, where the compressor can operate normally. Otherwise, if the state machine for entering heat pump mode is executed according to the cooling / dehumidification mode, it will first enter pre-start state one. In pre-start state one, the compressor will stop and wait at 0 speed for a period of time (preset time one), such as 10 seconds, before entering running state one. Therefore, the existence of waiting state one prevents the system from entering pre-start state, thus avoiding unnecessary compressor shutdown.

[0064] From the perspective of thermal management system principles, when transitioning from air conditioning off state or cooling / dehumidification mode to heat pump mode or hot gas bypass mode, theoretically, a compressor 0-speed stage is required due to the time needed for the expansion valve and other actuators to operate, as well as fundamental limitations such as refrigerant flow reversal. In general state machine designs, this conventional state machine transition between hot gas bypass mode and heat pump mode can essentially be used. However, the existence of "waiting state one" and "waiting state two" nodes avoids this unnecessary compressor shutdown.

[0065] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A multi-state machine switching control method based on hot gas bypass and heat pump mode, characterized in that, The multi-state machine switching control method comprises the following steps: S1, starting the air conditioning system, and switching the air conditioning system to the corresponding state machine for operation based on the switching conditions of the hot gas bypass state machine and the heat pump state machine; S2, the operating state machine first enters an initialization state, and determines whether the waiting state jump condition is met, if yes, the state machine jumps into the waiting state, otherwise, it is further determined whether the pre-starting condition is met, if yes, the state machine enters the pre-starting state, otherwise, the initialization state is maintained; The step S2, after the hot gas bypass state machine enters the pre-starting state, comprises the following sub-steps: A1, determining whether the air conditioning system still meets the operating state condition of the current state machine, if yes, the hot gas bypass state machine enters the pressure building state after a preset time two; A2, after the hot gas bypass state machine enters the pressure building state, the air conditioning system is controlled to build pressure, and a judgment is made based on the pressure building condition, if the air conditioning system meets the pressure building condition, the current state machine enters the operating state to control the air conditioning system to run, otherwise, it enters the shutdown state to control the air conditioning system to stop; A3, after the air conditioning system enters the shutdown state in the step A2, the current state machine enters the pressure balance state after a preset time three to balance the high and low pressures in the air conditioning system, and then enters the pressure flushing state after a preset time four to perform flushing processing, and after the flushing processing, the hot gas bypass state machine reenters the pressure building state after a preset time five to perform cyclic pressure building processing until the air conditioning system meets the pressure building condition to enter the operating state; The pre-starting state, the pressure building state, the operating state, the shutdown state, the pressure balance state and the pressure flushing state in the hot gas bypass state machine constitute a parent node of the hot gas bypass state machine, and when the hot gas bypass state machine does not meet the operating state condition, it directly enters the shutdown state from any state in the parent node; S3, after the current state machine jumps into the waiting state, it is determined whether the operating state condition is met, if yes, the current state machine enters the operating state to control the air conditioning system to run, otherwise, it is further determined whether the switching condition of the remaining state machine is met, if yes, the air conditioning system is switched to the corresponding state machine for operation, otherwise, the original state machine reenters the initialization state to realize the switching control between the multiple state machines.

2. The multi-state machine switching control method based on hot gas bypass and heat pump mode according to claim 1, wherein, The switching condition of the hot gas bypass state machine in the step S1 is that the ambient temperature is less than a preset value one, the switching condition of the heat pump state machine is that the ambient temperature is less than a preset value two, and the preset value one is less than the preset value two.

3. The multi-state machine switching control method based on hot gas bypass and heat pump mode of claim 1, wherein, In the step S2, after the heat pump state machine enters the pre-starting state, it is determined again whether the air conditioning system still meets the operating state condition of the current state machine, if yes, the heat pump state machine enters the operating state after a preset time one, otherwise, it returns to the initialization state.

4. The multi-state machine switching control method based on hot gas bypass and heat pump mode of claim 1, wherein, The pre-starting condition of the hot gas bypass state machine entering the pre-starting state in the step S2 comprises a condition one and a condition two, the priority of the condition one is higher than that of the condition two, and the determination of the hot gas bypass state machine entering the pre-starting state comprises the following sub-steps: S21, judging whether the air conditioning system meets condition one, if yes, the hot gas bypass state machine will enter the stay state from the initialization state, otherwise, maintaining the initialization state; S22, the hot gas bypass state machine entering the stay state will further judge whether it meets condition two, if yes, entering the pre-start state, otherwise, maintaining the stay state.

5. The multi-state machine switching control method based on hot gas bypass and heat pump mode of claim 4, wherein, The condition one for the hot gas bypass state machine entering the pre-start state is whether the air conditioning system meets the switching condition of the hot gas bypass state machine, and the condition two for the hot gas bypass state machine entering the pre-start state is whether the high pressure and the low pressure of the air conditioning system reach the balance threshold and the hot gas bypass state machine has no fault.

6. The multi-state machine switching control method based on hot gas bypass and heat pump mode of claim 1, wherein, After the air conditioning system enters the shutdown state in the step A1, the current state machine will enter the pressure balance state after a preset time three, and then judge whether the air conditioning system meets the delay condition or the pressure condition, if yes, neither of them is met, further judging whether it meets the switching condition of the current state machine, if not, entering the initialization state, otherwise, entering the stay state to control the air conditioning system to be closed.

7. The multi-state machine switching control method based on hot gas bypass and heat pump mode of claim 1, wherein, The hot gas bypass state machine entering the running state from the waiting state includes the following sub-steps: S31, judging whether the air conditioning system still meets the running state condition of the current state machine, if yes, performing the flushing treatment from the flushing state; S32, after the flushing treatment, entering the pressure building state from the flushing state after a preset time five, and performing the pressure building treatment circularly until the air conditioning system meets the pressure building condition to enter the running state, and controlling the air conditioning system to run.

Images