Stop control method of variable frequency controller and variable frequency air conditioner

Abstract

The application provides a shutdown control method of a variable frequency controller and a variable frequency air conditioner. The variable frequency controller is used for controlling the operation of a compressor. The method comprises the following steps: collecting the phase current of the compressor, and estimating the rotor phase position of the compressor according to the phase current; determining the shutdown timing of the compressor according to the rotor phase position of the compressor, wherein the rotor phase position of the compressor is located outside a first preset phase interval at the shutdown timing, and the first preset phase interval is the first phase interval with the maximum vibration and stress after the current moment; and shutting down the inverter driving signal used for driving the compressor at the shutdown timing. The PFC circuit driving signal is shut down or the output DC voltage value of the PFC circuit is reduced at a preset moment before the compressor is shut down. This method avoids the occurrence of large amplitude vibration and noise at the shutdown moment of the compressor, and avoids the overshoot of the DC voltage at the shutdown moment, thereby improving the reliability of the variable frequency air conditioner.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of variable frequency air conditioners, and particularly relates to a shutdown control method of a variable frequency controller and a variable frequency air conditioner. BACKGROUND

[0002] At present, a variable frequency air conditioner has a large amplitude of vibration and noise when it is shut down, which not only affects the service life of the variable frequency air conditioner, but also may cause harm to personal and property safety. SUMMARY

[0003] In the technical field of variable frequency air conditioners, in order to solve the above technical problems, the purpose of the present application is to provide a shutdown control method of a variable frequency controller and a variable frequency air conditioner.

[0004] According to an aspect of the present application, a shutdown control method of a variable frequency controller is provided, the variable frequency controller being used for controlling the operation of a compressor, and the method comprising:

[0005] acquiring a phase current of the compressor, and estimating a rotor phase position of the compressor according to the phase current;

[0006] determining a shutdown time of the compressor according to the rotor phase position of the compressor, wherein the rotor phase position of the compressor is outside a first preset phase interval at the shutdown time, and the first preset phase interval is a first phase interval with the maximum vibration and stress after a current time of the compressor;

[0007] turning off an inverter driving signal for driving the compressor at the shutdown time to shut down the compressor.

[0008] According to another aspect of the present application, a shutdown control device of a variable frequency controller is provided, the variable frequency controller being used for controlling the operation of a compressor, and comprising:

[0009] an acquisition and estimation module configured to acquire a phase current of the compressor, and estimate a rotor phase position of the compressor according to the phase current;

[0010] a shutdown time determination module configured to determine a shutdown time of the compressor according to the rotor phase position of the compressor, wherein the rotor phase position of the compressor is outside a first preset phase interval at the shutdown time, and the first preset phase interval is a first phase interval with the maximum vibration and stress after a current time of the compressor;

[0011] a turning off module configured to turn off an inverter driving signal for driving the compressor at the shutdown time to shut down the compressor.

[0012] In some embodiments of the present application, based on the foregoing scheme, the shutdown timing is a first time period or a first time point; the first time period is a time period during which the rotor phase position of the compressor reaches a second preset phase interval, the second preset phase interval being a first phase interval with minimum vibration and stress of the compressor after a current time point; the first time point is a time point at which the rotor phase position of the compressor reaches a preset phase point, the preset phase point being a first phase point with minimum vibration and stress of the compressor after the current time point.

[0013] In some embodiments of the present application, based on the foregoing scheme, the variable frequency controller comprises a power factor correction circuit, and before the rotor phase position of the compressor is estimated according to the phase current, the shutdown module is further configured to: after receiving a control signal for indicating shutdown of the compressor, shut down a power factor correction drive signal for driving the power factor correction circuit or reduce a direct current voltage value output by the power factor correction circuit.

[0014] In some embodiments of the present application, based on the foregoing scheme, before the phase current of the compressor is collected and the rotor phase position of the compressor is estimated according to the phase current, the collection and estimation module is further configured to: after the power factor correction drive signal is shut down, wait for a predetermined delay.

[0015] In some embodiments of the present application, based on the foregoing scheme, a time length of the predetermined delay is negatively correlated with a size of the phase current of the compressor.

[0016] In some embodiments of the present application, based on the foregoing scheme, the control signal is a compressor shutdown instruction, and the shutdown module is configured to: after receiving the compressor shutdown instruction, determine a shutdown timing of the power factor correction drive signal according to an operating frequency of the compressor or an alternating current voltage signal of the variable frequency controller; and shut down the power factor correction drive signal according to the shutdown timing of the power factor correction drive signal.

[0017] In some embodiments of the present application, based on the foregoing scheme, the shutdown module is configured to: determine whether the operating frequency of the compressor is greater than a preset frequency value; if the operating frequency of the compressor is greater than the preset frequency value, reduce the operating frequency of the compressor to the preset frequency value, and take a time point at which the operating frequency of the compressor reaches the preset frequency value as the shutdown timing of the power factor correction drive signal; and if the operating frequency of the compressor is equal to or lower than the preset frequency value, take a current time point as the shutdown timing of the power factor correction drive signal.

[0018] In some embodiments of the present application, based on the foregoing scheme, the control signal is an AC voltage value of the variable frequency controller lower than a preset voltage value, and the shutdown module is configured to: if it is detected that the AC voltage value of the variable frequency controller is lower than the preset voltage value, immediately shutting down a power factor correction driving signal for driving the power factor correction circuit.

[0019] In some embodiments of the present application, based on the foregoing scheme, the control signal is a compressor shutdown instruction, the variable frequency controller is further configured to drive the DC fan to rotate, and the shutdown module is configured to: after receiving the compressor shutdown instruction, determining whether the operating frequency of the compressor is greater than a preset frequency value; in the case where the operating frequency of the compressor is greater than the preset frequency value, reducing the operating frequency of the compressor to the preset frequency value; reducing a DC voltage value output by the power factor correction circuit to a target value; and after shutting down the compressor, the shutdown module is further configured to: restoring the DC voltage value output by the power factor correction circuit to a normal value to enable the DC fan to continue to operate, wherein the normal value is greater than the target value.

[0020] According to another aspect of the present application, there is provided a computer readable medium having stored thereon a computer program which, when executed by a processor, implements the shutdown control method of the variable frequency controller as described in the above embodiments.

[0021] According to another aspect of the present application, there is provided a variable frequency air conditioner, comprising:

[0022] a compressor;

[0023] a variable frequency controller configured to control the rotating speed of the compressor, the variable frequency controller comprising a master control unit configured to execute the method as described in the above embodiments.

[0024] From the above technical solutions, the embodiments of the present application have at least the following advantages and positive effects:

[0025] For the shutdown control method of the variable frequency controller and the variable frequency air conditioner provided in the embodiments of the present application, when it is needed to shut down the compressor, the phase current of the compressor is first collected, and the rotor phase position of the compressor is estimated according to the phase current, then the shutdown timing of the compressor is determined according to the rotor phase position of the compressor, and finally, the shutdown of the compressor is realized by shutting down the inverter driving signal used for driving the compressor at the shutdown timing. Since the rotor phase position of the compressor is outside the first preset phase interval at the shutdown timing, and the first preset phase interval is the first phase interval with the maximum vibration and stress after the current time of the compressor, i.e., the rotor phase position of the compressor can avoid the phase interval with the maximum vibration and stress at the shutdown timing, the large amplitude vibration and noise at the shutdown time of the compressor is avoided, the service life of the variable frequency air conditioner is prolonged, and the personal and property safety is ensured.

[0026] It should be understood that the general description above and the following detailed description are only exemplary and cannot limit the present application. BRIEF DESCRIPTION OF DRAWINGS

[0027] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0028] Figure 1 is a working principle schematic diagram of a variable frequency controller according to an exemplary embodiment;

[0029] Figure 2 is a flow chart of a shutdown control method of a variable frequency controller according to an exemplary embodiment;

[0030] Figure 3 is a flow chart of details of step 210 in the embodiment according to an exemplary embodiment; Figure 2 is a flow chart of steps before step 230 in the embodiment according to an exemplary embodiment;

[0031] Figure 4 is a flow chart of details of step 230 in the embodiment according to an exemplary embodiment; Figure 3 is a flow chart of details of step 210 in the embodiment according to an exemplary embodiment;

[0032] Figure 5 is a flow chart of determining the shutdown timing of the power factor correction driving signal according to the running frequency of the compressor according to an exemplary embodiment;

[0033] Figure 6 is a flow chart of steps before step 230 in the embodiment according to an exemplary embodiment; Figure 3

[0034] Figure 7 is a schematic diagram of the suction and exhaust working state of a rotor type compressor according to an exemplary embodiment; ​

[0035] Figure 8 is a block diagram of a shutdown control device of a variable frequency controller according to an exemplary embodiment. DETAILED DESCRIPTION

[0036] The exemplary embodiments will be described in detail with reference to the accompanying drawings. In the following description, unless otherwise denoted, the same numbers in different drawings denote the same or similar elements. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. Instead, they only describe examples of devices and methods consistent with some aspects of the present application, as detailed in the appended claims.

[0037] In addition, the accompanying drawings are only schematic and are not necessarily drawn to scale. Identical reference numerals denote the same or similar parts throughout the several views of the drawings and a repetitive description is omitted. Some of the blocks in the drawings are functional blocks that do not necessarily correspond to a physical or logical entity.

[0038] Variable frequency appliances, represented by variable frequency air conditioners, are provided with a variable frequency controller, which usually contains a PFC (Power Factor Correction) circuit.

[0039] With the development of variable frequency technology, small-capacity energy storage capacitor variable frequency technology has been increasingly applied. The energy storage capacitor capacity used in this technology is generally half of that of the conventional variable frequency energy storage scheme, or even lower. Meanwhile, PFC technology is constantly updated, and high frequency is the development trend of PFC, and the inductance value is also getting smaller and smaller.

[0040] Currently, the scheme used in the related art is to simultaneously turn off the compressor and the PFC at shutdown, which results in a consequence that the energy stored in the energy storage inductor is quickly released to the energy storage capacitor. With the decrease of the energy storage capacitor, the energy will cause the voltage value of the capacitor to rise sharply. If the input AC power is very high, such as 264V, and is at a 90-degree power phase amplitude, an abnormally high voltage will be generated on the energy storage capacitor, which will cause overvoltage protection and generate high electrical stress on the related unit circuit in the later stage.

[0041] On the other hand, when sudden power failure or shutdown according to instructions is encountered, for single rotor or similar structure compressors, since the shutdown timing of the variable frequency compressor inverter drive signal is not properly selected, there is randomness. When the shutdown timing is exactly at a position where the rotor torque is large, after the inverter drive signal is disconnected, the rotor loses driving torque, the gas in the compression chamber pushes the rotor to move in the opposite direction, and the compressed gas will flow back quickly, generating a large instantaneous vibration and stress.

[0042] To this end, the application first provides a shutdown control method of a variable frequency controller. Through the method, the above defects can be overcome, and when the compressor stops running, the compressor can be prevented from generating large amplitude vibration and noise, and the DC voltage stress of the variable frequency controller and the maximum instantaneous vibration and stress amplitude of the entire machine at the shutdown moment can be reduced. The shutdown control method of the variable frequency controller provided in the embodiments of the application can be applied to electronic devices such as variable frequency air conditioners and variable frequency refrigerators provided with a variable frequency controller.

[0043] Figure 1 is a schematic diagram of the working principle of a variable frequency controller according to an example embodiment. Please refer to Figure 1 , the variable frequency controller includes a PFC circuit 110, an inverter circuit 120, an alternating voltage sampling unit 130, a current sampling unit 140, a direct current voltage sampling unit 150, and a main control unit 160. The variable frequency controller is used to drive the operation of a CMP 170, that is, a compressor, wherein the PFC circuit 110 includes an IGBT, a fast recovery diode, and an inductor, the input end thereof is connected to a rectifier bridge stack, and the output thereof is connected to an energy storage electrolytic capacitor. The main control unit 160 is electrically connected with the alternating voltage sampling unit 130, the direct current voltage sampling unit 150, and the current sampling unit 140, respectively. In addition to driving the compressor, the variable frequency controller can also drive the operation of a direct current fan (not shown). Figure 1

[0044] Figure 2 is a flowchart of a shutdown control method of a variable frequency controller according to an example embodiment. The shutdown control method of the variable frequency controller provided in the embodiment can be executed by Figure 1 the main control unit in the embodiment, and the variable frequency controller is used to control the operation of a compressor. As Figure 2 shown, the method can include the following steps:

[0045] Step 230: The phase current of the compressor is collected, and the rotor phase position of the compressor is estimated according to the phase current.

[0046] Please continue to refer to Figure 1 shown, the phase current of the compressor can be collected by the current sampling unit 140, and the phase current is input to the main control unit 160.

[0047] Figure 3 is a flowchart of the steps before step 230 in Figure 2 the embodiment according to an example embodiment. Please refer to Figure 3 shown, the variable frequency controller includes a power factor correction circuit, and the steps before step 230 can include the following steps:

[0048] ​In step 210, after receiving the control signal indicating that the compressor is to be stopped, the power factor correction drive signal for driving the power factor correction circuit is turned off or the DC voltage value output by the power factor correction circuit is reduced.

[0049] The control signal can be a compressor stop command or an AC voltage value of the frequency conversion controller being lower than a preset voltage value. If the control signal is received, i.e., the compressor stop command is received or it is monitored that the AC voltage value of the frequency conversion controller is lower than the preset voltage value, it is determined that the compressor needs to be stopped. After it is determined that the compressor needs to be stopped, the FPC drive signal for driving the FPC circuit is turned off or the DC voltage value output by the FPC circuit is reduced. Please refer to Figure 1 As shown in the figure, the main control unit 160 can output the drive signal of the FPC circuit, and thus the main control unit 160 can turn off the drive signal. The main control unit 160 can also control the DC voltage value output by the FPC circuit.

[0050] In the embodiment of the present application, since the power factor correction drive signal and the inverter drive signal for driving the compressor are not turned off at the same time but are turned off in sequence, the continued operation of the compressor after the power factor correction drive signal is turned off can consume the energy stored in the energy storage inductor of the power factor correction circuit and the energy storage capacitor of the frequency conversion controller, reduce the voltage value on the energy storage capacitor, avoid overvoltage protection, and reduce the electrical stress on the subsequent unit circuit. Therefore, the operation reliability of the frequency conversion air conditioner is improved, the service life of the frequency conversion air conditioner is prolonged, and harm to personal and property safety is avoided. In addition, reducing the DC voltage value output by the power factor correction circuit can also reduce the voltage value on the energy storage capacitor, thereby reducing the electrical stress on the subsequent unit circuit.

[0051] In one embodiment of the present application, the control signal is that the AC voltage value of the frequency conversion controller is lower than a preset voltage value, and after receiving the control signal indicating that the compressor is to be stopped, the power factor correction drive signal for driving the power factor correction circuit is turned off or the DC voltage value output by the power factor correction circuit is reduced, including:

[0052] If it is detected that the AC voltage value of the frequency conversion controller is lower than the preset voltage value, the power factor correction drive signal for driving the power factor correction circuit is immediately turned off.

[0053] The AC voltage sampling unit 130 can monitor the AC voltage signal of the frequency conversion controller, and determine whether the AC voltage value is lower than the preset voltage value. When the AC voltage value is lower than the preset voltage value, it can be considered that the low voltage or power-off state occurs. For example, when the voltage of the main power supply bus of the frequency conversion controller disappears, it can be considered that the power-off state occurs. At this time, the power factor correction drive signal for driving the power factor correction circuit needs to be immediately turned off.

[0054] Figure 4 is shown according to an exemplary embodiment Figure 3 The flow chart of the details of step 210 in the embodiment. In Figure 4 In the embodiment, the control signal is the compressor shutdown instruction. Please refer to Figure 4 As shown in the figure, step 210 can specifically include the following steps:

[0055] Step 211, after receiving the compressor shutdown instruction, determining the shutdown time of the power factor correction drive signal according to the operating frequency of the compressor or the AC voltage signal of the frequency conversion controller.

[0056] When it is determined according to the compressor shutdown instruction that the compressor needs to be shutdown, the power factor correction drive signal will not be immediately turned off, but the shutdown time of the power factor correction drive signal will be determined according to the operating frequency of the compressor or the AC voltage signal of the frequency conversion controller, and then the power factor correction drive signal will be turned off according to the shutdown time.

[0057] Figure 1 The AC voltage sampling unit 130 shown in the embodiment can sample the AC voltage signal.

[0058] In an embodiment of the present application, determining the shutdown time of the power factor correction drive signal according to the operating frequency of the compressor or the power supply AC signal of the frequency conversion controller includes: taking the zero-crossing point of the AC voltage signal of the frequency conversion controller as the shutdown time of the power factor correction drive signal.

[0059] Specifically, the AC voltage sampling unit 130 transmits the AC voltage signal to the main control unit 160, the main control unit 160 detects the AC input voltage value, and obtains the zero-crossing point information through the software zero-crossing judgment, and then takes the zero-crossing point in the zero-crossing point information as the shutdown time. The main control unit 160 has the software zero-crossing detection function. At the zero-crossing point, the energy storage in the PFC inductor is 0, which will not cause the DC voltage of the rear-stage electrolytic capacitor to be boosted, thereby reducing the electrical stress generated on the rear-stage unit circuit.

[0060] The operating frequency of the compressor can be 50HZ, 60HZ, etc. Determining the shutdown time of the power factor correction drive signal according to the operating frequency of the compressor is as shown in Figure 5 the figure.Figure 5 is a flow chart for determining the turn-off timing of the power factor correction drive signal according to the operating frequency of the compressor according to an exemplary embodiment. As shown in Figure 5 includes the following steps:

[0061] Step 510, determine whether the operating frequency of the compressor is greater than a preset frequency value.

[0062] The preset frequency value can be stored in the main control unit 160, and the preset frequency value can be set according to experience.

[0063] Step 520, if the operating frequency of the compressor is greater than the preset frequency value, reduce the operating frequency of the compressor to the preset frequency value, and take the time when the operating frequency of the compressor reaches the preset frequency value as the turn-off timing of the power factor correction drive signal.

[0064] By reducing the operating frequency of the compressor to a lower value, the following two effects can be achieved: first, the total machine current will decrease, and the maximum energy storage in the PFC inductor will also decrease; second, after reducing the frequency, the pressure in the compressor system will decrease, which can reduce the vibration and stress generated by the compressor stopping running at the shutdown time from the source.

[0065] Step 530, if the operating frequency of the compressor is equal to or lower than the preset frequency value, take the current time as the turn-off timing of the power factor correction drive signal.

[0066] In the case where the operating frequency of the compressor is equal to or lower than the preset frequency value, the power factor correction drive signal will be turned off directly without waiting.

[0067] In the embodiments of the present application, only in the case where the operating frequency of the compressor is equal to or lower than the preset frequency value, the PFC drive signal is allowed to be turned off, which can reduce the vibration and stress generated by the compressor stopping running at the shutdown time from the source, and can also reduce the electrical stress, avoid overvoltage protection, thereby ensuring the stability and reliability of the whole machine operation.

[0068] Step 212, turn off the power factor correction drive signal according to the turn-off timing of the power factor correction drive signal.

[0069] The power factor correction drive signal is turned off when the operating frequency of the compressor is equal to or lower than the preset frequency value or the AC voltage signal of the power supply crosses zero.

[0070] Figure 6 is a flow chart for determining the turn-off timing of the power factor correction drive signal according to the operating frequency of the compressor according to an exemplary embodiment. As shown in Figure 3 the flow chart of the steps before step 230 in the embodiment. Please refer to Figure 6As shown, before the phase current of the compressor is collected and the rotor phase position of the compressor is estimated according to the phase current, the following steps can also be included:

[0071] Step 220, after the power factor correction drive signal is turned off, a predetermined delay is waited for.

[0072] That is, the power factor correction drive signal is first turned off, and after a predetermined delay, the step after step 230 in the embodiment of the present application is executed, that is, the inverter drive signal is turned off again.

[0073] In the embodiment of the present application, the power factor correction drive signal is first turned off, and then the inverter drive signal is turned off. As for how long after the power factor correction drive signal is turned off the inverter drive signal is turned off, it can be set according to actual conditions.

[0074] The purpose of waiting for a predetermined delay is to consume the energy on the energy storage electrolytic capacitor through the operation of the compressor, reduce the DC voltage value on the electrolytic capacitor, so that after the PFC is turned off, the energy stored in the inductor of the PFC circuit has an object to consume, and when the predetermined delay time is reached, the voltage on the energy storage capacitor has dropped, and a voltage surge will not occur., the inverter drive signal of the compressor can be turned off.

[0075] In an embodiment of the present application, the length of time of the predetermined delay is negatively related to the size of the phase current of the compressor.

[0076] That is, the larger the phase current of the variable frequency compressor, the shorter the length of time of the predetermined delay.

[0077] Since the larger the phase current of the compressor, the larger the output load of the compressor, the more power it consumes, and the faster the energy storage on the electrolytic capacitor and the energy storage in the PFC circuit is consumed, the predetermined length of time of the delay needs to be shortened to ensure that the predetermined delay is adapted to the phase current of the compressor.

[0078] Next, how to estimate the rotor phase position of the compressor is introduced.

[0079] The compressor can be a rotary compressor, and the main control unit 160 has a rotor position estimation function.

[0080] Figure 7 is a schematic diagram of the suction and exhaust working state of a rotary compressor according to an exemplary embodiment.

[0081] The compressor can be a rotary compressor, and the main control unit 160 has a rotor position estimation function. Figure 7 is a schematic diagram of the suction and exhaust working state of a rotary compressor according to an exemplary embodiment. Please refer to Figure 7As shown in A of FIG. 1, the core unit of a rotary compressor can include a cylinder 710, a rotor 730, a vane 720, and two side end covers (not shown). Please refer to Figure 7 As shown in A-F of FIG. 1, the space between the rotor and the cylinder is in a crescent shape, and the vane divides it into two spaces, i.e., a suction chamber and a compression chamber. The shaded part in the figure represents the compressed and exhaust process, and the blank part represents the suction process. As the rotor rotates, the suction chamber and the compression chamber change periodically, realizing the suction, compression, and exhaust of the gas.

[0082] A is in the end of suction state, and the pressure in it is the suction pressure. When the compressor is shut down at this rotor phase position, the shut-down vibration and stress are the smallest, and thus, it is preferred to shut down the compressor at this time.

[0083] B is an intermediate state. The small white chamber on the right has been converted into a suction chamber and is in the suction state. The chamber in the shaded part on the left has been converted into a compression chamber and is in the compression state. The pressure at this time is higher than the suction pressure.

[0084] In C, the suction chamber on the right continues to expand, and the gas continuously enters from the suction port. The compression chamber on the left continues to compress, the chamber becomes smaller, and the pressure continuously increases.

[0085] In D, the suction chamber on the right continues to expand, and the gas continuously enters from the suction port. The chamber on the left continues to compress, the pressure continuously increases, until the pressure is high enough to push the exhaust valve open. At this time, the compressed gas is discharged through the exhaust valve, and the exhaust process begins. The pressure described in this figure is the highest, and the shut-down vibration and stress are the highest. The reason is that after the compressor is shut down, the rotor loses the moment of force, the high-pressure gas in the compression chamber drives the rotor to run reversely, discharges the gas to the suction port, and completes the process in a very short time, causing the maximum vibration and stress. Therefore, it is necessary to avoid shutting down the compressor at this stage.

[0086] In E, the suction chamber on the right continues to expand, and the gas continuously enters from the suction port. The compression chamber on the left continues the exhaust process.

[0087] In F, the compression chamber on the left is reduced to zero, the exhaust process is completed, and the exhaust valve is closed. The suction chamber on the right expands to the maximum, the suction process is completed, and it reaches the state of A. The operation is repeated in this way.

[0088] It can be seen that, in order to reduce the vibration and stress caused by the shutdown of the compressor, the rotor phase position shown in D should be avoided as much as possible, and the rotor phase position shown in A should be preferred for the shutdown of the compressor.

[0089] Of course, Figure 7 The rotor phase positions shown are only schematic. In fact, considering the inertia of the rotor, the actual rotor phase position at the time of shutdown needs to be corrected and determined according to the actual measurement results.

[0090] The main control unit 160 can estimate the electronic phase of the rotor by using a FOC (Field-Oriented Control) algorithm, and further obtain the estimated rotor phase position in combination with the number of pole pairs of the motor and the phase current.

[0091] Specifically, according to the FOC algorithm, the main control unit can accurately estimate the electronic period phase of the rotor. For a 2-pole-pair compressor, 2 electronic periods correspond to one mechanical period of the rotor operation. For a 3-pole-pair or more-pole-pair compressor, 3 or more electronic periods correspond to one mechanical period of the rotor operation. In one mechanical period of the rotor operation, as the rotor operation position is different, the phase current of the compressor presents periodic increase and decrease. The electronic period corresponding to the minimum current corresponds to the mechanical period phase of the rotor torque minimum. The electronic period corresponding to the maximum current corresponds to the mechanical period phase of the rotor torque maximum. By using the system measurement method, the optimal shutdown point phase and the worst shutdown point phase of the compressor rotor can be accurately determined.

[0092] In step 240, the shutdown timing of the compressor is determined according to the rotor phase position of the compressor. The rotor phase position of the compressor is outside the first preset phase interval at the shutdown timing. The first preset phase interval is the first phase interval with the maximum vibration and stress after the current time of the compressor.

[0093] According to the above-mentioned accurate estimation of the electronic period and the determination of the rotor in the mechanical period according to the size of the phase current, the rotor mechanical phase of the compressor can be accurately determined, so that the shutdown timing can be determined according to the rotor mechanical phase.

[0094] Please refer to Figure 7 As shown in FIG. 7, the rotor 730 repeatedly moves in the cylinder 710. The rotor 730 moves one cycle, i.e., one mechanical period, each mechanical period including a phase interval with the minimum vibration and stress and a phase interval with the maximum vibration and stress. The first phase interval with the maximum vibration and stress after the current time is the phase interval with the maximum vibration and stress in the first mechanical period after the current time.

[0095] The time period corresponding to the first preset phase interval is the time period before and after the opening moment of the exhaust port of the compressor. The pressure of the rotor is the largest, and the phase current of the compressor is the largest. Therefore, the time period needs to be avoided. The first time when the rotor phase position of the compressor avoids the first preset phase interval can be selected as the shutdown timing of the compressor.

[0096] Therefore, the time when the rotor phase position of the compressor avoids the first preset phase interval can be selected as the shutdown timing, which can reduce the vibration and noise at the shutdown timing of the compressor.

[0097] In an embodiment of the present application, the shutdown timing is a first time period or a first time point; the first time period is a time period during which the rotor phase position of the compressor reaches a second preset phase interval, and the second preset phase interval is a first phase interval after the current time point at which vibration and stress are the smallest; the first time point is a time point at which the rotor phase position of the compressor reaches a preset phase point, and the preset phase point is a first phase point after the current time point at which vibration and stress are the smallest.

[0098] The first phase interval after the current time point at which vibration and stress are the smallest is a phase interval at which vibration and stress are the smallest in a first mechanical cycle after the current time point.

[0099] Therefore, the shutdown timing of the compressor is set to the first time period or the first time point, so that vibration and noise occurring at the shutdown time point of the compressor can be further reduced.

[0100] In an embodiment of the present application, the shutdown timing of the compressor is determined according to the rotor phase position of the compressor, and the method comprises:

[0101] If the direct-current voltage value output by the power factor correction circuit is above a specified voltage value, the first time point is preferentially selected as the shutdown timing of the compressor, and when the rotor phase position of the compressor cannot reach the first phase point after the current time point at which vibration and stress are the smallest, a first time point at which the rotor phase position of the compressor avoids the first preset phase interval is selected as the shutdown timing of the compressor; or

[0102] If the direct-current voltage value output by the power factor correction circuit is below the specified voltage value, a time point that is reached first among the first time point and a second time point is selected as the shutdown timing of the compressor, and the second time point is a first time point at which the rotor phase position of the compressor avoids the first preset phase interval.

[0103] The specified voltage value can be obtained according to experimental evaluation.

[0104] If the direct-current voltage value output by the power factor correction circuit is large, it indicates that the compressor will continue to operate for a relatively long time, and at this time, the shutdown timing is determined by selecting a corresponding determination method of the shutdown timing according to the priority among the two determination methods of the shutdown timing, so that the amplitude of the shutdown vibration and stress of the compressor can be reduced to a greater extent; if the direct-current voltage value output by the power factor correction circuit is small, it indicates that the compressor will continue to operate for a very short time, and at this time, the amplitude of the shutdown vibration and stress of the compressor can be rapidly reduced by selecting the time point that is reached first.

[0105] The direct-current voltage value output by the power factor correction circuit can be sampled by a direct-current voltage sampling unit 150 shown in FIG. 1. Figure 1

[0106] ​Step 250, when the inverter drive signal for driving the compressor is turned off to stop the compressor at shutdown.

[0107] When the rotor phase position of the compressor reaches the first preset phase interval with the minimum vibration and stress after the current time, or the rotor phase position of the compressor avoids the second preset phase interval with the maximum vibration and stress after the current time, or the rotor phase position of the compressor reaches the first phase point with the minimum vibration and stress after the current time, the inverter drive signal is turned off.

[0108] In an embodiment of the present application, the control signal is a compressor stop command, the frequency conversion controller is further configured to drive the DC fan to rotate, and after receiving the control signal for indicating to stop the compressor, the power factor correction drive signal for driving the power factor correction circuit is turned off or the DC voltage value output by the power factor correction circuit is reduced, including:

[0109] After receiving the compressor stop command, it is determined whether the operating frequency of the compressor is greater than a preset frequency value.

[0110] In the case where the operating frequency of the compressor is greater than the preset frequency value, the operating frequency of the compressor is reduced to the preset frequency value.

[0111] The DC voltage value output by the power factor correction circuit is reduced to a target value.

[0112] After stopping the compressor, the method further includes:

[0113] The DC voltage value output by the power factor correction circuit is restored to a normal value to enable the DC fan to continue to operate, wherein the normal value is greater than the target value.

[0114] Before reducing the DC voltage value output by the power factor correction circuit to the target value, it can be determined whether the operating frequency of the compressor is greater than the preset frequency value, in the case where the operating frequency of the compressor is greater than the preset frequency value, the operating frequency of the compressor is reduced to the preset frequency value, and in the case where the operating frequency of the compressor is less than or equal to the preset frequency value, the step of reducing the operating frequency of the compressor is skipped, and then the DC voltage value output by the power factor correction circuit is reduced to the target value.

[0115] By reducing the operating frequency of the compressor to the preset frequency value first and then reducing the DC voltage value output by the power factor correction circuit to a preset lower target value, the overshoot of the PFC output voltage can be significantly reduced.

[0116] The embodiments of the present application enable the DC fan to continue to operate while the compressor is stopped.

[0117] In one embodiment of the present application, the inverter drive signal for driving the DC fan can be turned off at the same time as the inverter drive signal for driving the compressor is turned off.

[0118] The embodiment of the present application realizes stopping the DC fan at the same time as the compressor is stopped.

[0119] In summary, according to the stop control method of the frequency converter provided by the embodiment of the present application, by setting a new PFC and inverter drive signal turn-off timing control scheme for the compressor, the PFC output voltage short-time overshoot is significantly reduced at the moment when the compressor stops running, the DC voltage stress of the frequency converter and the maximum instantaneous vibration and stress amplitude of the whole machine at the moment of stopping are reduced, and the operation reliability of the whole machine is improved. Similarly, the selection of the compressor stop position under the power-off condition also maximally reduces the amplitude of the vibration and stress generated by the compressor when stopping.

[0120] The present application also provides a stop control device of a frequency converter. The following is a device embodiment of the present application.

[0121] Figure 8 is a block diagram of a stop control device of a frequency converter according to an exemplary embodiment. Please refer to Figure 8 The stop control device 800 of the frequency converter includes:

[0122] The acquisition and estimation module 810 is configured to acquire the phase current of the compressor and estimate the rotor phase position of the compressor according to the phase current;

[0123] The stop timing determination module 820 is configured to determine the stop timing of the compressor according to the rotor phase position of the compressor, wherein the rotor phase position of the compressor is outside the first preset phase interval at the stop timing, and the first preset phase interval is the first phase interval with the maximum vibration and stress after the current time of the compressor;

[0124] The turn-off module 830 is configured to turn off the inverter drive signal for driving the compressor at the stop timing to stop the compressor.

[0125] According to another aspect of the present application, a computer readable medium having a computer program stored thereon is also provided, and the computer program is executed by a processor to implement the stop control method of the frequency converter as described in the above embodiments.

[0126] The computer readable medium can be a tangible device that can retain and store instructions for execution by a processor. The computer readable medium can be, but is not limited to, an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of the computer readable medium include the following: a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), a static random access memory (SRAM), a portable compact disc read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanically encoded device such as punch-cards or punched-tape, a

[0127] Computer program / instructions described herein can be downloaded from a computer readable medium to respective computing / processing devices or to external computer or external storage devices via a network, for example, the Internet, a local area network, a wide area network and / or a wireless network. The network can comprise copper transmission cables, optical transmission fibers, wireless transmission, routers, firewalls, switches, gateway computers and / or edge servers. A network adapter card or network interface in each computing / processing device receives computer readable program instructions from the network and forwards the computer readable program instructions for storage in a computer readable medium within the respective computing / processing device.

[0128] Computer readable program instructions for carrying out operations of the present application can be assembly instructions, instruction-set-architecture (ISA) instructions, machine instructions, machine dependent instructions, microcode, firmware instructions, state-setting data, or either source code or object code written in any combination of one or more programming languages, including an object oriented programming language such as Smalltalk, C++ or the like, and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The computer readable program instructions can execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer can be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection can be made to an external computer (for example, through the Internet using an Internet Service Provider). In some embodiments, electronic circuitry including, for example, programmable logic circuitry, field-programmable gate array (FPGA), or programmable logic array (PLA) can execute the computer readable program instructions by utilizing state information of the computer readable program instructions to personalize the electronic circuitry, in order to perform aspects of the present application.

[0129] According to another aspect of the present application, there is also provided a variable frequency air conditioner, the variable frequency air conditioner comprising:

[0130] a compressor;

[0131] a variable frequency controller for controlling a rotation speed of the compressor, the variable frequency controller comprising a master control unit for performing the method as described in the above embodiments.

[0132] Other embodiments of the present application will be apparent to those skilled in the art from consideration of the specification and practice of the aspects disclosed herein. For example, the methods and systems described herein can be used in various applications, including but not limited to the applications described above. The present application is intended to cover any variations, uses or adaptations of this application including such departures from the present disclosure as come within known

[0133] It is understood that the present application is not limited to the precise structures described and illustrated above and that various modifications and changes can be made without departing from the scope of the present application. The scope of the present application is limited only by the claims that follow.

Claims

1. A stop control method of a variable frequency controller, characterized by, The variable frequency controller comprises a power factor correction circuit, and the variable frequency controller is configured to control operation of the compressor, and the method comprises: after receiving a control signal for indicating stopping of the compressor, turning off a power factor correction drive signal for driving the power factor correction circuit or reducing a direct current voltage value output by the power factor correction circuit, the control signal being a compressor stopping instruction; acquiring a phase current of the compressor and estimating a rotor phase position of the compressor according to the phase current; determining a stopping timing of the compressor according to the rotor phase position of the compressor, wherein the rotor phase position of the compressor is outside a first preset phase interval at the stopping timing, and the first preset phase interval is a first phase interval with maximum vibration and stress of the compressor after a current time point; turning off an inverter drive signal for driving the compressor to stop the compressor at the stopping timing; the turning off of the power factor correction drive signal after receiving the control signal for indicating stopping of the compressor comprises: after receiving the compressor stopping instruction, determining a turning off timing of the power factor correction drive signal according to an operating frequency of the compressor or an alternating current voltage signal of the variable frequency controller, the turning off timing comprising a zero-crossing point of the alternating current voltage signal of the variable frequency controller; turning off the power factor correction drive signal at the turning off timing of the power factor correction drive signal.

2. The method of claim 1, wherein, the stopping timing is a first time period or a first time point; the first time period is a time period in which the rotor phase position of the compressor reaches a second preset phase interval, and the second preset phase interval is a first phase interval with minimum vibration and stress of the compressor after the current time point; the first time point is a time point in which the rotor phase position of the compressor reaches a preset phase point, and the preset phase point is a first phase point with minimum vibration and stress of the compressor after the current time point.

3. The method of claim 1, wherein, before the acquiring of the phase current of the compressor and the estimating of the rotor phase position of the compressor according to the phase current, the method further comprises: after turning off the power factor correction drive signal, waiting for a predetermined delay.

4. The method of claim 3, wherein, a time length of the predetermined delay is negatively correlated with a size of the phase current of the compressor.

5. The method of claim 1, wherein, the determining of the turning off timing of the power factor correction drive signal according to the operating frequency of the compressor or the alternating current voltage signal of the variable frequency controller comprises: determining whether the operating frequency of the compressor is greater than a preset frequency value; if the operating frequency of the compressor is greater than the preset frequency value, reducing the operating frequency of the compressor to the preset frequency value, and taking a time point at which the operating frequency of the compressor reaches the preset frequency value as the turning off timing of the power factor correction drive signal; if the operating frequency of the compressor is equal to or lower than the preset frequency value, taking a current time point as the turning off timing of the power factor correction drive signal.

6. The method of claim 1, wherein, The control signal is an AC voltage value of the variable frequency controller lower than a preset voltage value, and the step of shutting off the power factor correction driving signal for driving the power factor correction circuit or reducing a DC voltage value output by the power factor correction circuit after receiving the control signal for indicating stopping of the compressor comprises: immediately shutting off the power factor correction driving signal for driving the power factor correction circuit if the AC voltage value of the variable frequency controller is detected to be lower than the preset voltage value.

7. The method of claim 1, wherein, The control signal is a compressor stopping instruction, and the variable frequency controller is further configured to drive a DC fan to rotate, and the step of shutting off the power factor correction driving signal for driving the power factor correction circuit or reducing a DC voltage value output by the power factor correction circuit after receiving the control signal for indicating stopping of the compressor comprises: after receiving the compressor stopping instruction, determining whether a running frequency of the compressor is greater than a preset frequency value; in a case where the running frequency of the compressor is greater than the preset frequency value, reducing the running frequency of the compressor to the preset frequency value; reducing a DC voltage value output by the power factor correction circuit to a target value; after stopping the compressor, the method further comprises: restoring the DC voltage value output by the power factor correction circuit to a normal value to enable the DC fan to continue running, wherein the normal value is greater than the target value.

8. A variable frequency air conditioner, characterized by comprising: comprises: a compressor; a variable frequency controller configured to control a rotating speed of the compressor, the variable frequency controller comprising a master control unit configured to perform the method according to any one of claims 1 to 7.

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