Disclosure of Invention
The invention solves the problem that the air conditioner in the prior art is likely to cause the compressor to lose step and cause damage when the air conditioner runs under heavy load and overload.
In order to solve the above problems, the present invention provides a control method for heavy load overload protection of an air conditioning system, which comprises the following steps:
acquiring the running current of the compressor during running;
determining the torque current and the rotating speed of the compressor according to the running current;
judging whether a predicted step-out condition is met or not according to the torque current and the rotating speed;
and if the predicted step-out condition is met, controlling to close the load output.
The invention monitors the running state of the compressor in real time and predicts whether the compressor is in a heavy load running out-of-step state or not according to the torque current and the rotating speed of the compressor. And the load output is timely closed when the compressor is predicted to be in the step-out state, and excessive current cannot be generated so as to protect the compressor. And can effectively reduce controller components and parts electric stress damage, reduce the risk that components and parts became invalid. And the invention carries out data analysis and control on the basis of the circuit of the existing air-conditioning system, and does not increase the production cost.
Further, the predicting out-of-synchronization condition includes: and the torque current is greater than a preset current threshold value in a first time interval, and the variation of the rotating speed is greater than a preset rotating speed variation threshold value in a second time interval.
The invention selects the key parameters to monitor according to the system characteristics, and takes the change condition of the key parameters as the judgment condition, thereby effectively judging whether the compressor is in the out-of-step state and ensuring the reliability of the system operation.
Further, the predicting out-of-synchronization condition includes: and the times that the variation of the rotating speed is greater than the preset rotating speed variation threshold value in the third time interval are greater than the preset times.
According to the method, the compressor is predicted to possibly reach the out-of-step state by judging the frequency of unstable rotating speed control caused by the overload of the compressor and combining the detection of the torque current of the compressor, so that the accuracy of judging the out-of-step of the compressor can be improved.
Further, when the number of times that the variation amount of the rotation speed is greater than the preset rotation speed variation threshold value within the third time interval is greater than the preset number of times includes: and when the frequency of the change quantity of the rotating speed which is greater than the preset rotating speed change threshold value in the third time interval is less than or equal to the preset frequency, clearing the frequency.
The invention can count the unstable times of the rotating speed control by zero clearing when the timing time expires, thereby ensuring that the accuracy of judging the out-of-step state is not influenced by introducing larger errors.
Further, the controlling to turn off the load output includes: turning off a control signal of an intelligent power module connected to the compressor.
The invention can timely close the load output when predicting that the compressor is in the step-out state, thereby effectively avoiding the generation of large current and protecting the compressor and other components from being damaged.
Further, the determining the torque current and the rotation speed of the compressor according to the operation current comprises:
determining a three-phase current of the compressor according to the running current;
performing coordinate transformation according to the three-phase current to obtain an exciting current and the torque current of the compressor;
determining a back electromotive force of the compressor according to the exciting current and the torque current;
and determining the rotating speed of the compressor according to the counter electromotive force.
According to the invention, each operation parameter of the system is detected according to the circuit of the existing air-conditioning system, and the key parameter is obtained by corresponding calculation, so that no additional hardware sensor is introduced, and the design development cost and the production cost are effectively reduced.
Another objective of the present invention is to provide a control device for heavy load overload protection of an air conditioning system, so as to effectively monitor the operation state of a compressor and avoid damage to the compressor and components due to step loss.
In order to achieve the purpose, the technical scheme of the invention is realized as follows:
a control device for heavy load overload protection of an air conditioning system comprises:
the acquisition unit is used for acquiring the running current when the compressor runs;
the processing unit is used for determining the torque current and the rotating speed of the compressor according to the running current; the controller is also used for judging whether a predicted step-out condition is met or not according to the torque current and the rotating speed;
and the control unit is used for controlling to close the load output when the predicted step-out condition is met.
The invention monitors the running state of the compressor in real time and predicts whether the compressor is in a heavy load running out-of-step state or not according to the torque current and the rotating speed of the compressor. And the load output is timely closed when the compressor is predicted to be in the out-of-step state when the overload is overweight, so that the compressor cannot be damaged due to larger current mutation. And can effectively reduce controller components and parts electric stress damage, reduce the risk that components and parts became invalid.
The third objective of the present invention is to provide a control device for heavy load overload protection of an air conditioning system, which can accurately predict the out-of-step state of a compressor and perform overload protection in time.
In order to achieve the purpose, the technical scheme of the invention is realized as follows:
a control device for heavy load overload protection of an air conditioning system comprises a memory and a processor:
the memory for storing a computer program;
the processor is used for realizing the control method for the heavy load overload protection of the air conditioning system when the computer program is executed.
A fourth object of the present invention is to provide an air conditioner that can avoid the risk of step-out due to heavy load operation and improve the reliability of system operation.
In order to achieve the purpose, the technical scheme of the invention is realized as follows:
an air conditioner comprises the control device for the heavy load overload protection of the air conditioning system.
Compared with the prior art, the air conditioner and the control device for the heavy load overload protection of the air conditioning system have the same beneficial effects, and are not repeated herein.
The fifth objective of the present invention is to provide a computer-readable storage medium to implement the above control method for heavy load overload protection of an air conditioning system.
In order to achieve the purpose, the technical scheme of the invention is realized as follows:
a computer readable storage medium storing a computer program which, when read and executed by a processor, implements the control method for heavy load overload protection of an air conditioning system as described above.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.
The air conditioning system mainly comprises a compressor, a condenser, an evaporator, a four-way valve and other components, wherein the components are sequentially connected through pipelines to form a closed system. The refrigerant is continuously subjected to Carnot circulation in the system, and exchanges heat with the surrounding environment through conversion between gas phase and liquid phase, so that the refrigeration and heating functions are realized. The compressor is used as a core component, and the performance and the reliability of the whole air conditioning system are influenced.
In order to further improve the efficiency of the air conditioner compressor, most current variable frequency air conditioner compressors adopt permanent magnet synchronous motors, which are synchronous motors adopting rare earth permanent magnets to replace excitation windings, have the same speed regulation characteristic as a direct current motor, and simultaneously have the advantages of good starting performance, small temperature rise, high-efficiency operation under the condition of light load and the like. However, when the system is in heavy load overload operation, the compressor is in a step-out risk, the phase current of the compressor is increased instantly, and the compressor and other components are damaged.
The invention provides a control method and a device for heavy load overload protection of an air conditioning system, which can accurately predict whether a compressor is in an out-of-step state when the system is in heavy load operation, and timely close load output to protect the compressor.
Fig. 1 is a schematic diagram illustrating a principle of heavy load overload protection of an air conditioning system according to an embodiment of the present invention, in which an AC (direct current) power source is rectified and filtered by a rectifying device (Bridge) to be used as a system power source. L1 is an inductor, and is connected in series to the post-stage dc bus, and controls the inductor L1 to store energy by controlling the on and off of an IGBT (Insulated Gate Bipolar Transistor) in the circuit, thereby completing the boosting function. The IGBT is bridged between the direct current buses, the collector of the IGBT is connected with one end of the inductor L1 and then connected to the direct current buses, the emitter of the IGBT is connected to the other direct current bus, and the grid of the IGBT is connected to a PFC (Power Factor Correction) module.
The fast recovery power diode D1 is also connected in series with the dc bus, with its anode connected to the collector of the IGBT and its cathode connected to the anode of the electrolytic capacitor C. The electrolytic capacitor C is also connected between the direct current buses in a bridging mode and used for maintaining the direct current bus voltage to be stable direct current voltage. The anode of the electrolytic capacitor C is connected with the cathode of the fast recovery power diode D1 and then connected to a direct current bus, and the cathode of the electrolytic capacitor C is connected with one end of the sampling resistor R3 and then connected to another direct current bus. The other end of the sampling resistor R3 is connected to one end of an IPM (Intelligent Power Module) Module.
Three output ports of the IPM module are respectively connected to three phases of a motor Comp of the compressor, and PWM 1-PWM 6 are control end signals of 6 IGBTs in the IPM module, which are PWM pulse width signals and are used as control signals for driving the IGBTs to be switched on and off. PWM 1-PWM 6 controls the switch state of each power device in the IPM module to realize the phase change control of the motor winding of the compressor. In the embodiment of the invention, when the compressor is predicted to lose step, the output of the PWM 1-PWM 6 is closed to prevent the damage to the compressor.
The following describes a control method for heavy load overload protection of an air conditioning system according to an embodiment of the present invention with reference to fig. 1 and 2.
Fig. 2 is a schematic flow chart of a control method for heavy load overload protection of an air conditioning system according to an embodiment of the present invention, which includes steps S11 to S14.
In step S11, the operation current at the time of compressor operation is acquired. In the embodiment of the invention, the operating current Is when the compressor Is running Is sampled and obtained at the sampling resistor R3. The invention reasonably predicts whether the compressor is in the out-of-step state or not according to the running state, namely the change condition of each key parameter, by monitoring the running state of the system in real time, thereby carrying out corresponding control in time and realizing overload protection.
In step S12, a torque current and a rotation speed of the compressor are determined according to the operation current, wherein the torque current of the compressor can effectively reflect the operation load of the compressor, and the rotation speed of the compressor can effectively reflect whether the rotation speed control is stable. The combination of the torque current and the rotating speed of the compressor can effectively predict whether the compressor is in the out-of-step state, and the reliability of system operation is ensured.
Fig. 3 is a schematic flow chart illustrating the process of determining the torque current and the rotational speed of the compressor according to the embodiment of the present invention, which includes steps S121 to S124.
In step S121, a three-phase current of the compressor is determined according to the operation current. In the embodiment of the invention, the three-phase currents Iu, Iv and Iw of the current compressor can be obtained according to the running current Is of the compressor sampled in real time at the sampling resistor R3.
In step S122, coordinate transformation is performed based on the three-phase current to obtain an excitation current and the torque current of the compressor. Fig. 4 is a schematic diagram illustrating a principle of coordinate transformation of a motor according to an embodiment of the present invention, in which coordinate systems commonly used in a permanent magnet synchronous motor include a three-phase stationary coordinate system (ABC coordinate system), a two-phase stationary coordinate system (α β coordinate system), and a two-phase rotating coordinate system (dq coordinate system), and a strongly coupled ac motor can be decoupled and controlled by coordinate transformation to be equivalent to a dc motor, so as to perform precise control. In the embodiment of the invention, I alpha and I beta are obtained according to Clark transformation, and Id and Iq are obtained according to Park transformation, wherein the Clark transformation is the transformation from a three-phase stationary ABC coordinate system to a two-phase stationary alpha beta coordinate system, and the Park transformation is the transformation from the two-phase stationary alpha beta coordinate system to a two-phase rotating dq coordinate system. The specific transformation formula is as follows:
wherein, I α and I β respectively represent current components of α and β axes in the two-phase stationary coordinate system, and Id and Iq respectively represent current components of d and q axes in the two-phase rotating coordinate system, that is, an exciting current and a torque current.
In step S123, a back electromotive force of the compressor is determined based on the excitation current and the torque current. In an embodiment of the invention, the following motor equations are used:
Ud=Rs×Id-Wr×Lq×Iq+Ed
Uq=Rs×Iq+Wr×Ld×Id+Eq
the back emf of the compressor can be found:
wherein Ud and Uq represent control voltage, Rs represents stator winding resistance, Wr represents compressor rotation speed, and Ld and Lq represent inductance on d and q axes, respectively.
In step S124, the rotation speed of the compressor is determined according to the back electromotive force. From the counter electromotive forces Ed and Eq of the compressor obtained by the above equation, the compressor rotation speed Wr ═ arctan (Ed/Eq) can be obtained. According to the invention, corresponding calculation is carried out according to the circuit of the existing air conditioning system, no additional hardware sensor is introduced, and the design development cost and the production cost are effectively reduced.
In step S13, it is determined whether a predicted step-out condition is satisfied based on the torque current and the rotation speed. In an embodiment of the present invention, the predicting out-of-synchronization condition includes:
(1) the torque current is greater than a preset current threshold for a first time interval. If the torque current Iq is greater than the predetermined current threshold Iq _ threshold for a first, sustained time interval (e.g., T1ms), then condition (1) is deemed to be true, otherwise condition (1) is not true.
(2) And the variation of the rotating speed in the second time interval is larger than a preset rotating speed variation threshold value. When the command target rotating speed is reached, the rotating speed Wr of the compressor is recorded in real time, the rotating speed Wr at the time of recording t1 is Wr1, and the rotating speed Wr at the time of recording t2 is Wr2, so that the variation quantity delta Wr of the rotating speed is | Wr 1-Wr 2 |. If the amount of change Δ Wr of the rotational speed is greater than the preset rotational speed change threshold Δ Wr _ threshold in the second time interval (for example, T2ms), the condition (2) is considered to be satisfied, otherwise, the condition (2) is not satisfied.
In another embodiment of the present invention, the predicted out-of-synchronization condition comprises:
(3) the torque current is greater than a preset current threshold for a first time interval. If the torque current Iq is greater than the predetermined current threshold Iq _ threshold for a first, sustained time interval (e.g., T1ms), then condition (3) is deemed to be true, otherwise condition (3) is not true.
(4) And the frequency of the variable quantity of the rotating speed larger than the preset rotating speed change threshold value in the third time interval is larger than the preset frequency. If Δ Wr > - Δ Wr _ threshold occurs frequently during a third time interval (e.g., T3ms) that continues. And recording the occurrence number Cnt of the condition, and if the occurrence number Cnt is larger than a preset number Cnt _ threshold, determining that the condition (4) is satisfied, otherwise, not determining that the condition (4) is satisfied. This indicates that the compressor is overloaded, causing unstable speed control or is about to go out of step. And when the time Cnt is less than or equal to the preset time Cnt _ threshold in the continuous third time interval, clearing the time Cnt and restarting counting in the next timing period.
When the conditions (1) and (2) are met simultaneously or the conditions (3) and (4) are met simultaneously, the system is considered to meet the condition of predicting step loss, and overload protection is needed to avoid damage caused by the step loss of the compressor. The value ranges of T1, T2 and T3 are 0.1-200 ms, the value range of a preset current threshold Iq _ threshold is 10-100A, the value range of a preset rotating speed change threshold delta Wr _ threshold is 3-140 Hz, and the value range of a preset time Cnt _ threshold is 2-10000. The values of the numerical values can be set according to the actual model, or can be set according to experience, and can be obtained according to experimental data.
In step S14, if the predicted step-out condition is satisfied, control turns off the load output. The turning off the load output includes: and turning off signals of a control end of the IPM module connected to the compressor, namely turning off the PWM 1-PWM 6. In the embodiment of the invention, the IPM module is an inverter consisting of 6 IGBTs, wherein the IGBTs are circularly switched on and off according to a certain sequence so as to apply voltage to a stator coil of the compressor and realize the phase change control of a motor winding of the compressor. After the PWM 1-PWM 6 is closed, damage to the compressor and other components in the system caused by sudden change of the phase current of the compressor can be avoided.
The invention monitors the running state of the compressor in real time and predicts whether the compressor is in a heavy load running out-of-step state or not according to the torque current and the rotating speed of the compressor. And the load output is timely closed when the compressor is predicted to be in the step-out state, and excessive current cannot be generated so as to protect the compressor. And can effectively reduce controller components and parts electric stress damage, reduce the risk that components and parts became invalid. And the invention carries out data analysis and control on the basis of the circuit of the existing air-conditioning system, and does not increase the production cost.
Fig. 5 is a schematic structural diagram of a control device 500 for heavy load overload protection of an air conditioning system according to an embodiment of the present invention, which includes an obtaining unit 501, a processing unit 502, and a control unit 503, where:
the obtaining unit 501 is used for obtaining an operation current when the compressor operates.
The processing unit 502 is configured to determine a torque current and a rotation speed of the compressor according to the operating current, and further configured to determine whether a predicted step-out condition is satisfied according to the torque current and the rotation speed.
The control unit 503 is configured to control to turn off the load output when the predicted out-of-step condition is satisfied.
Fig. 6 is a schematic structural diagram of a control device 600 for heavy load overload protection of an air conditioning system according to an embodiment of the present invention, which includes a memory 601 and a processor 602, wherein:
the memory 601 is used to store computer programs. In embodiments of the present invention, Memory 601 may include a computer system readable medium in the form of volatile Memory, such as Random Access Memory (RAM) and/or cache Memory.
The processor 602 is configured to implement the control method for heavy load overload protection of the air conditioning system as described above when executing the computer program.
The control device 600 for heavy load overload protection of the air conditioning system according to the embodiment of the present invention may be a computer device such as a microcontroller.
The invention monitors the running state of the compressor in real time and predicts whether the compressor is in a heavy load running out-of-step state or not according to the torque current and the rotating speed of the compressor. And the load output is timely closed when the compressor is predicted to be in the out-of-step state when the overload is overweight, so that the compressor cannot be damaged due to larger current mutation. And can effectively reduce controller components and parts electric stress damage, reduce the risk that components and parts became invalid.
The embodiment of the invention also provides an air conditioner which is provided with the control device 600 for the heavy load overload protection of the air conditioning system. In the embodiment of the invention, the air conditioner has a system circuit as shown in fig. 1, and the running current of the compressor is sampled at a sampling resistor R3. In other embodiments of the present invention, the air conditioner may further include various other sensors for detecting parameters such as an operating current and a rotational speed of the compressor to determine the step-out state.
An embodiment of the present invention further provides a computer-readable storage medium, where a computer program is stored, and when the computer program is read and executed by a processor, the method for controlling heavy load overload protection of an air conditioning system as described above is implemented.
Although the present invention is disclosed above, the present invention is not limited thereto. Various changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.