436results about How to "Avoid frequent start and stop" patented technology

The invention discloses a whole vehicle energy management method for an internal combustion generating extend range type electric vehicle. The SOC level of a current electric vehicle storage battery is obtained according to voltage and charging and discharging current information of the two ends of the storage battery, a high SOC threshold and a low SOC threshold are set to determine the on-off state of a range extender, and excessive charging and discharging of the storage battery and frequent start and stop of the range extender are avoided. In a range extend mode, drive demanded power of the whole vehicle is obtained according to discharge voltage and current information of a drive motor and a controller of the drive motor, an economic travel line of an internal combustion engine of the range extender and the current SOC value of the storage battery serve as bases, the optimal operation condition of the range extender is reasonably determined, charging and discharging demands of the storage battery are taken into consideration, accordingly whole vehicle dynamic performance and fuel economical efficiency are guaranteed, and meanwhile the energy storage level of the storage battery is optimized.

The invention discloses a parallel compressor selection and configuration method for preventing a compressor from being frequently started up and shut down. The method comprises the following steps of: 1, calculating calculation adjustment coefficients of performance parameters of the compressor for transformation from nominal conditions to design conditions; 2, calculating a curve of change of the refrigerating capacity and power consumption of a direct-current variable-frequency compressor with operating frequency; 3, calculating performance parameters of an air conditioner unit under the design conditions; 4, determining the range of operating frequency of the direct-current variable-frequency compressor; and 5, selecting and configuring the parallel fixed-frequency compressor. The parallel compressor selection and configuration method for preventing the compressor from being frequently started up and shut down has the advantages that the accuracy of compressor selection is improved and the reliability when compressors with different output capacities are connected in parallel is increased.

The invention discloses a method for distributing active power of a wind power station, comprises the steps of predicating the power information and classifying a wind power generating unit into five types according to the operating parameter and fault of the wind power station, combining with the unit classification and executing an increasing and decreasing power distribution strategy, thereby the distribution of the active power of the wind power station is optimized and the use ratio of the wind power unit is improved. As the factors of the unit, such as the actual operating state, parameter and fault are considered in the active power distribution method, the fluctuation of the output power of the wind power station is varied slowly and stable operation is achieved by reasonably distributing the power to the units according to the increasing and decreasing power adjusting ability of the unit, and the real-time output power of the wind power station reaches the setting value of the wind power station. At the same time, the declining power distributing strategy is divided into deep amplitude limit power distributing strategy and light amplitude limit power distributing strategy, thereby the declining power requirement is met in the distribution process, the frequent start or stop of the unit is avoided and reasonable operation of the unit is ensured.

The invention discloses a compressor unit control method, and aims to provide a compressor energy regulating and controlling method of a modular cold / hot water unit, wherein the compressor energy regulating and controlling method is stable for control, high in control precision and capable of effectively ensuring the working life of the unit. In the invention, the running states of compressors are adjusted together, according to the average water inlet temperature and the water inlet temperature variation rate of sequentially numbered module groups between a water inlet path and a water outlet path, and the compressors can be controlled to start and stop according to a certain order at certain time interval, so that the compressors are started and stopped more smoothly and the impact on the grid is reduced; in an operation process, the number of the compressors to be run can be determined more accurately according to the different working conditions, so that the frequently start and stop phenomena of the compressors are reduced and the start loss is reduced; meanwhile, the compressor units can be ensured to meet load demands faster and more accurately, thus the advantages of saving energy and prolonging the lives of units are achieved. The compressor energy regulating and controlling method disclosed by the invention can be widely applied in the cold / hot water unit control field.

A refrigeration control method capable of intelligent scheduling is used for realizing steady operation of a compressor in a refrigeration control system which is composed of a plurality of evaporators, comprising the following steps: current temperature of each evaporator and inlet pressure of the compressor are collected by a temperature sensor and a pressure sensor; according to the collected variation tendency of the inlet pressure, the relationship between overall refrigerating effect Q of the current evaporator and refrigerating effect M according to the output power of the compressor can be obtained; in different conditions of 'when Q>M, Q<M and Q=M', the running state of every evaporator is scheduled by the temperature of the evaporators to adjust the overall refrigerating output of the evaporators or the output power of the compressor, thereby realizing the steady operation of the compressor and achieving optimal energy conversation effect.

The invention provides a heat insulation control method and device for a heat pump water heater and a heat pump water heater. The heat insulation control method comprises the following steps: acquiring the current water temperature T5 inside a water tank; comparing the current water temperature T5 inside the water tank with an acceptable temperature value TL, and when the current water temperature T5 inside the water tank is smaller than the acceptable temperature value TL, judging whether the start-up condition of a heat pump mainframe is satisfied, if yes, starting up the heat pump mainframe to heat water in the water tank, and if no, judging whether the start-up condition of an auxiliary electric heater is satisfied, if yes, starting up the auxiliary electric heater to heat water in the water tank. The heat insulation control method for the heat pump water heater can prevent frequent start and stop of the auxiliary electric heater, so that the service life of the auxiliary electric heater is prolonged; frequent starting of multiple auxiliary electric heaters is also avoided; under the premise of not influencing normal use of other electric appliances of users, water comfort degree is guaranteed for the users and the use cost is lowered.

The invention relates to a pure electric vehicle cooling system control method based on deep reinforcement learning, which comprises the following steps: first, obtaining the temperature of the powerbattery of the pure electric vehicle, the working current of the power battery, and the ambient temperature information; Construct DDPG algorithm model, carry on reinforcement learning training, get agroup of optimal PID control parameters of electronic pump. The PID control quantity is obtained by the PID input quantity, and the electronic pump is controlled based on the PID control quantity. The work of the electronic pump changes the flow rate of coolant in the power battery cooling system to achieve the purpose of cooling the power battery. At the same time, the information of the power battery is transmitted to the environment sensing module, and the first step is returned to circulate the whole process. The invention introduces the depth reinforcement learning into the PID control algorithm, the depth reinforcement learning can better interact with the environment, has the self-learning function, adapts to the dynamic characteristics of the uncertain system, and therefore can adapt to the complex and changeable characteristics of the pure electric vehicle running environment, and realizes on-line control under different actual scenes.

The invention relates to a stepped refrigerating system for recovering oil gas, which comprises a primary refrigerating system, a secondary refrigerating system and a tertiary refrigerating system, wherein the primary refrigerating system is connected with the secondary refrigerating system connected with the tertiary refrigerating system. The invention has the benefits that a refrigerant in a hot steam manner is directly used for performing the phase change defrosting (hot freon defrosting), and the energy efficiency ratio is high. Since the hot freon defrosting is carried out in a heat exchanger, so that the heat transfer speed and the defrosting speed are high, the defrosting time of a primary oil gas condenser and a secondary oil gas condenser is within 15 minutes, and the defrosting time of a tertiary oil gas condenser can also be within 30 minutes. The defrosting time is saved greatly.

The invention discloses a control method of a constant-speed conditioner. The control method comprises the following steps that the indoor environment temperature and the human body sensible temperature of the environment where the constant-speed conditioner is located are obtained; a comfort interval of the indoor environment temperature is judged according to the human body sensible temperature; and the indoor environment temperature is adjusted by controlling an indoor fan, an outer fan and an air guiding member of the constant-speed conditioner according to the comfort interval. According to the control method of the constant-speed conditioner, frequent start and stop of a compressor can be avoided during temperature adjustment and the energy consumption is reduced. The invention further discloses the constant-speed conditioner and an air conditioning system.

A hybrid electrical vehicle (HEV) control system and method, the control system comprising a transmission device (10), an engine power subsystem (20), a motor power subsystem (30) and a controller (40); the controller (40) enables the HEV to enter a hybrid power economical mode by controlling the engine power subsystem (20) and the motor power subsystem (30); if a detected current gradient signal is below or equal to a gradient lower threshold, and the SOC of a power battery (7) is below or equal to a first electric quantity threshold, or if the current gradient signal is below or equal to the gradient lower threshold, and the maximum allowable discharge power of the power battery (7) is below or equal to a first power threshold, then the controller (40) controls the HEV to operate in a low-power mode. In a parallel connection, the control system enables easy power matching, and provides high conversion efficiency and a high starting point of an engine, effectively reducing fuel consumption and emissions, reducing frequent engine start and stop, thus extending the service life of a starter, reducing noise during vehicle travel, and improving driving comfort.

The invention discloses a crossroad traffic signal lamp real time dynamic timing method, relating to the road traffic control field. The crossroad traffic signal lamp real time dynamic timing method comprises steps of defining phases of various traffic flow directions of a crossroad, determining a saturation flow of each phase, measuring multiple current flows of each phase, obtaining a biggest current flow of each phase, calculating a relative biggest flow ratio of each phase and crossroad flow intensity, designing a target function and solving the target function to obtain a theoretical effective green light time of each phase, determining a signal lamp cycle time according to the theoretical effective green light time of each phase and crossroad signal lamp total loss time, and determining the practical effective green light time of each phase according to a ratio of the relative biggest flow ratio of each phase to crossroad flow intensity in the signal lamp cycle. The crossroad traffic signal lamp real time dynamic timing method avoids the fact that the vehicle starts and stops frequently in a congestion road due to the short cycle, improves a traffic capacity of the congestion road, reduces the parking rate of the congestion rate and has good robustness.

The invention relates to a non-disturbance switching water pump control method comprising the following steps of: selecting different control manners of a water pump motor according to operation requirements of a water pump system; using a long-distance control manner of the water pump motor when a water pump normally works, so that a PLC (Programmable Logic Controller) performs monitoring and on-off control on a motor state automatically or according to set technological parameters; when the water pump has a fault and needs to maintain or carry out field emergency enablement, selecting an in-position control manner of the water pump motor which is operated to a field operation box; and realizing non-disturbance switching between the two modes when the motor continuously works through delay relays which are respectively arranged at each mode state in a mutual switching process. In a condition of not changing any technical requirement of the water pump system, the non-disturbance switching water pump control method provided by the invention can be used for not only realizing a control manner of mutually switching between a concentrated manner and a local manner of the water pump motor without being switched off, but also carrying out on-off operation on the field operation box and an HMI (Human-Machine Interface), so that the security reliability and operation convenience of the water pump system can be improved.

The invention discloses an EBM variable direction forming dynamic slicing method cooperated with an 840D numerical control system. The EBM variable direction forming dynamic slicing method comprises the steps of establishing a vertex array object VAO, adjusting a projection matrix to the slicing height during rendering of a three-dimensional model and outputting a two-dimensional section binary image through a reverse ray tracing algorithm; acquiring data of a contour line from the binary image through a two-dimensional contour extraction method, outputting coordinates of an end-to-end closedcontour, connecting all adjacent coordinates into straight lines and connecting all the straight lines end to end to form a closed curve; and dividing the contour data into a straight line part and acurve part with the starting point of the small straight lines with the included angle of 140 degrees as the segmentation point when the triangle tolerance is one, removing neighbor points, repeated points and internal points of the same straight lines, conducting segmentation fitting on a slicing data curve through a NURBS curve and then conducting dynamic slicing through the 840D numerical control system. Through the EBM variable direction forming dynamic slicing method, the computing time and conversion errors of STL files are reduced, and meanwhile, the phenomenon of over-accumulation of straight line inflection points is reduced.

The invention discloses an energy-saving control method for a compressed air industrial screw-type air compressor group control system. The method comprises automatic control of the number of air compressors and automatic loading and uploading control of screw-type air compressors. In the system, gray scale prediction of total run traffic is conducted to control start and stop of the air compressors, so that the frequent start and stop defect of the air compressors is overcome, and the system operation stability is greatly improved; meanwhile, automatic loading and uploading control of the screw-type air compressors is carried out, so that the system operating pressure is stable, the pressure fluctuation range is reduced, and a defect that the power consumption of a frequency converter is increased caused by modification of frequency conversion control of an air compressor group. The method has the characteristics that the energy utilization efficiency is high, and the system is flexible in operation and stable in running.

A hybrid electrical vehicle (HEV) control system and control method, the control system comprising a transmission device (10), an engine power subsystem (20), a motor power subsystem (30) and a controller (40); the controller (40) enables the HEV to enter a corresponding working mode by controlling the engine power subsystem (20) and the motor power subsystem (30). Upon reception of a switching instruction to switch to an electrical vehicle (EV) economical mode, if the controller (40) determines that the SOC of a power battery is greater than equal to a second electric quantity threshold, and the speed of the HEV is lower than or equal to a first speed threshold, the controller (40) then causes the HEV to switch from a hybrid power economical mode to the EV economical mode. Being connected in parallel, the engine power subsystem (20) and the motor power subsystem (30) in the control system of the HEV enable easy power matching, provide high conversion efficiency, reduce fuel consumption and emissions, and frequent engine start and stop, thus extending starter service life, reducing noise during vehicle travel, and improving driving comfort.

The invention discloses a fault diagnosis method and system which are used for solving the problems that equipment is started and stopped frequently in the prior art and the like. The fault diagnosis method comprises the following steps of: acquiring redundant measurement data; processing the redundant measurement data and performing fault diagnosis; triggering a fault program and running a restarting program; and setting a threshold value and a restarting hysteresis value during fault diagnosis. According to the method, a fan cannot be started normally after failing until an actually measured value of a part to be measured does not trigger the threshold value added with the restarting hysteresis value, so that the equipment safety is guaranteed, and a phenomenon that the fan is frequently started and stopped because of the same fault is avoided; when a key value of a wind driven power generator set is measured, unnecessary fault alarm can be well avoided by adopting a redundancy technology, so that manmade mistakes are avoided, alarm halt caused by hardware fault of a measurement sensor is reduced, the accuracy of a measured value is improved, and the wind driven power generator set has relatively high performance under a severe condition.

The invention relates to a method for controlling automatic starting and automatic stopping of wind turbine generators by using a wind power plant with minimum hourage deviation, and belongs to the technical field of running and controlling on a new energy connected electrical power system. According to a principle of fair-share scheduling, when control requirements can be met by continuously adjusting the active power of the grid-connected wind turbine generators, a starting and stopping mode is not used; if the wind turbine generators are required to be started, the wind turbine generators with low hourage are started; and if the wind turbine generators are required to be stopped, the wind turbine generators with high hourage are stopped preferentially. Starting and stopping of the wind turbine generators are controlled in a hourage sequencing mode; a phenomenon that a wind turbine generator is started and stopped frequently can be effectively avoided; and the service lives of the wind turbine generators are prolonged. The method can be used for substation systems running in the wind power plant, and the active power of the substation systems is automatically controlled, so that a suitable control strategy is implemented according to wind power generation running states and running states of the wind turbine generators; control instructions which are issued by a master scheduling station can be accurately traced; and the wind turbine generators can be scheduled fairly.

The invention discloses a control method for an air conditioner. The outlet water temperature Tewo and a set target temperature Td are acquired; a difference value delta T is calculated, wherein delta T=Tewo-Td; whether delta T is within a set difference value range or not is judged; if not, whether the water temperature change rate is within a set change rate range or not is judged; if not, whether the frequency of compressor starting / shutdown is within a set starting / shutdown frequency range or not is judged; if not, the compressor additional starting / reduction shutdown interval time is determined according to delta T, the water temperature change rate and the compressor starting / shutdown frequency, after the additional starting / reduction shutdown interval time is up, one compressor in a shutdown / start state is controlled to start / stop; and the difference value delta T, the water temperature change rate and the compressor starting / shutdown frequency are comprehensively considered, starting and stopping of compressors in a unit are controlled, and therefore frequent starting, caused by too-quick feedback of the water temperature, of the compressors is avoided, the service life of the compressors is prolonged, the water temperature fluctuation is relieved, and the requirement for comfort of a user is met.

The invention is suitable for the technical field of design of photovoltaic inverters, and provides a device for avoiding frequent start stop of a photovoltaic inverter and the photovoltaic inverter. The device comprises a power absorption unit which is connected in parallel between a photovoltaic direct current (dc) positive busbar and a photovoltaic dc negative busbar and is connected with an auxiliary power supply of the photovoltaic inverter, and the power absorption unit is used for using a transistor to absorb power output by a solar cell panel through the photovoltaic dc busbar before the auxiliary power supply is started, and for stopping absorbing the power output by a solar cell panel through the photovoltaic dc busbar after the auxiliary power supply is started. Compared with the existing mode of power absorption by using power resistors, the invention has the advantages of reducing the occupied area of a printed circuit board, reducing the space occupied by the integral photovoltaic inverter, obviously improving the power density and reducing the cost of the photovoltaic inverter.

The invention discloses a temperature control method for a proton exchange membrane fuel cell system for a vehicle, which comprises the following steps of: detecting the inlet temperature of a cooling loop of a fuel cell stack by using a temperature sensor, inputting the inlet temperature into a controller, and achieving cooling fan control based on the controller, wherein the cooling fan control comprises fuzzy logic adaptive proportional integral control and feedforward compensation control, a gain parameter of the proportional integral control is adaptively updated by a fuzzy logic algorithm, the load current of the fuel cell is used as disturbance and is used for feedforward compensation, and meanwhile, the opening degree of the fan is determined by the total heat dissipating capacity demand and the number of cooling fans; and finally, inputting a control signal output by the controller into an actuator of a thermal management subsystem to control the temperature of the cooling inlet of the fuel cell stack. The temperature control strategy provided by the invention can reduce the temperature fluctuation during the operation of the vehicle fuel cell engine, improve the system performance and prolong the service life.

The invention relates to a compressor speed regulating method. The compressor speed regulating method includes detecting a power voltage value before a compressor is started; controlling the compressor to be started at a high-speed gear when the power voltage value is larger than or equal to a preset starting voltage value; and controlling the compressor to be started at a low-speed gear when the power voltage value is smaller than the starting voltage value. By means of detecting power voltage and starting the compressor at the selected gear according to the power voltage, on the one hand, the compressor is more easily started at a low-voltage state, and on the other hand, the compressor can run normally at a high-voltage state. The invention further relates to a compressor speed regulating device and air conditioning equipment.

The invention discloses an electric air compressor control strategy and fault diagnosis method. The method comprises following specific steps: firstly, effectiveness of input signals is subject to judgment and treatment; secondly, an electric air compressor is operated and controlled; thirdly, according to signals in the control flow in the second step, the electric air compressor is subject to fault diagnosis; according to the method, the control strategy of the electric air compressor is provided, the specific method for the fault diagnosis in the control strategy is provided, under the condition that the input signals are normal, frequent starting and stopping of the air compressor can be effectively avoided, the service life of the air compressor is prolonged, it is ensured that water in an air storage barrel can be drained in time, and water accumulating is avoided; meanwhile, under the condition that the input signals are abnormal, the whole vehicle pressure value can be maintained to be above the brake safety pressure value all the time, brake safety is ensured, the fault can be effectively judged in time, the fault rate of a vehicle is reduced, and the vehicle operation efficiency is improved.

The invention relates to the technical field of mine drainage underground, in particular to a subdivision control method of a mine drainage system based on peak and valley electric charges. Accordingto the method, the mine inflow calculation and periodic filtering equalization method is used for obtaining the predicated water inflow q of one calculation period Tmin, the predicated water inflow qserves as the predicted value of peak avoiding and valley filling segmented decision making, the water level of a water sump is divided into four segments, and comprises the ultralow water level HLL,the low level HL, the high level HH and the ultra-high water level HHH, according to the peak and valley electric charges, 24 hours of one day are divided into four electric sections according to theelectricity price, the electric sections include a valley section, a peak section, a flat section I and a flat section II, a mathematic model of the water pump input number n with q, h and t is built,according to the value of the predicated water inflow q and the electric section information, the mathematic model is selected, the water pump value required to be input on the corresponding time segment is calculated, opening of water pumps with the corresponding number is controlled, automatic unmanned control is achieved, the mine drainage system is precisely controlled, the water pump frequent start and stop can be avoided, and the energy saving and cost saving effect is more obvious.

The invention relates to an output-restricted active power distribution method based on power prediction and applied to a wind power plant cluster. According to the output-restricted active power distribution method based on power prediction and applied to the wind power plant cluster, active output maximization and line loss minimization of the wind power plant cluster existing under the output-restricted condition serve as objective functions, the system safety, the wind power plant output power, the frequent starting and stopping of a wind power unit and the lower predicted power serve as constraint conditions, and the influence of the active power loss on a connecting line and short-term active power prediction errors is considered. According to the output-restricted active power distribution method based on power prediction and applied to the wind power plant cluster, the practicability is high, reduction of the wind curtailment electricity quantity of the wind power plant cluster is achieved by increasing the active output of the wind power plant cluster and lowering the active power loss inside the cluster, and the negative influence on the service life of the unit, the operation of wind power plants and system regulation of the frequent starting and stopping of the wind power unit can be weakened to a certain extent.

The invention relates to a combined quick-heating heat exchanger, which comprises an inner container and an electric heater. A heating portion of the electric heater is positioned in the inner container, an electricity inlet portion of the electric heater is arranged outside the inner container, and a hot water outlet is arranged on the upper portion of the inner container. The combined quick-heated heat exchanger is characterized by further comprising an outer container and a heat-exchange coiled pipe, the outer container is sleeved outside the inner container and mutually sealed with the inner container, a closed sandwich space is arranged between the outer container and the inner container, a refrigerant inlet communicated with the sandwich space is arranged on one side of the outer container, and a refrigerant outlet communicated with the sandwich space is arranged on the other side of the outer container. The heat-exchange coiled pipe is coiled outside the inner container and positioned in the sandwich space, a water inlet of the heat-exchange coiled pipe is communicated with tap water, and a water outlet of the heat-exchange coiled pipe is communicated with a water inlet at the bottom of the inner container. The combined quick-heating heat exchanger has the advantages that the combined quick-heating heat exchanger is high in heat exchange efficiency, easy in load adjustment, quick in fluid heating start and stable in outputted fluid temperature, and a heating system is more efficient, safer and more comfortable.

The invention discloses a liquid cooling system by utilizing condensation heat and air cooling to adapt to the refrigerating capacity, and the liquid cooling system comprises a refrigerating system, an emergency air cooling system and a cooling liquid circulating system; the refrigerating system comprises a compressor, a condenser, an expansion valve and an evaporator, which are sequentially and circularly connected with one another; the emergency air cooling system comprises an emergency air cooling heat exchanger which is connected with a user end; the cooling liquid circulating system comprises a solution tank which is connected with a liquid return outlet of the evaporator, and an outlet of the solution tank and a liquid return inlet of the evaporator are respectively connected with the user end; and the emergency air cooling heat exchanger is arranged on the side part of the condenser, an inlet of the emergency air cooling heat exchanger and the liquid return inlet of the evaporator are connected with the user end through a three-way valve, and an outlet of the emergency air cooling heat exchanger and the liquid return outlet of the evaporator are respectively connected with the inlet of the solution tank. The emergency air cooling heat exchanger and the condenser of the refrigerating system are assembled together in a superimposing way, the emergency air cooling system is operated while the refrigerating system is used for refrigerating, solution inside the emergency air cooling heat exchanger is heated by the condensation heat produced by the condenser through the combination of the structure, and the heated solution finally flows into the solution tank to be used for balancing the redundant refrigerating amount of the refrigerating system, so that the high precision in temperature adjustment of the solution can be realized.

The invention discloses a multi-connected air-conditioning outdoor unit, a multi-connected air-conditioning system and a control method for its small-load operation. The multi-connected air-conditioning outdoor unit includes: a compressor, a first one-way valve, a first four-way valve, The second four-way valve, the first outdoor heat exchanger, the second outdoor heat exchanger, the first electronic throttling component, the second electronic throttling component, the gas side shut-off valve, the liquid side shut-off valve and the second one-way valve. When it is detected that the evaporation temperature of the indoor heat exchanger is low, the system is in low-load cooling operation. By switching part of the outdoor heat exchanger to the evaporator, bypassing part of the refrigerant, unloading part of the capacity output of the compressor, and increasing the low pressure of the system, Increase the evaporation temperature of the indoor heat exchanger, prevent the indoor unit from freezing without stopping the machine, and solve the problem of excessive output of the large-displacement compressor under small load operation, avoid frequent system start-up and stop, and improve user comfort and safety. System operation reliability.

The invention discloses an air conditioner control method and device and an air conditioner unit with the air conditioner control device. An air conditioner is operated in a refrigeration mode. The method comprises the steps that a compressor in the air conditioner is recognized to be operated at the lowest operation frequency; the temperature difference between the current indoor environment andthe set temperature of the air conditioner is obtained; and the temperature difference is compared with a preset first threshold value, and if the temperature difference is smaller than or equal to the first threshold value, the air conditioner is controlled to reduce output of the refrigerating capacity. Accordingly, the compressor is prevented from being frequently started and stopped, energy issaved, reliability of the compressor is improved, indoor heat comfort is improved, and the technical problem that the output refrigerating capacity of the air conditioner operated at the lowest frequency is larger than the indoor practically-required refrigerating capacity in the prior art is solved.

The invention discloses a control and protection method for an air conditioner and the air conditioner. The control and protection method comprises the following steps that an actual pressure value ofthe air conditioner is detected, and whether the air conditioner operates abnormally or not is checked when the actual pressure value changes to a preset check value; and the preset check value is less than the preset high-voltage protection value and greater than the preset low-voltage protection value. By the adoption of the control and protection method for the air conditioner and the air conditioner, frequent starting and stopping of the air conditioner can be avoided, the air conditioner is effectively protected and the working efficiency is improved.

The invention provides a control method and device for energy efficiency optimization of a VRF system. The method comprises the steps that the work mode of an indoor unit is acquired; the set temperature and the indoor environment temperature corresponding to the work mode are acquired, and the indoor unit load corresponding to the work mode is calculated according to the set temperature and the indoor environment temperature; if the work mode is a refrigeration mode, the target superheat degree of the indoor unit is controlled according to the indoor unit load corresponding to the refrigeration mode; and if the work mode is a heating mode, the target supercooling degree of the indoor unit is controlled according to the indoor unit load corresponding to the heating mode. Thus, according tothe indoor unit load corresponding to the work mode, the target superheat degree or the target supercooling degree of the indoor unit is controlled, the VRF system is prevented from being frequentlystarted and stopped in a small-load operation state, and therefore the energy efficiency of the system and the use experience of users are improved.