Zero-crossing detection method, detection system, PG motor and air conditioner

Abstract

The present invention provides a zero-crossing detection method, detection system, PG motor, and air conditioner. The zero-crossing detection method includes: determining the current power frequency; executing a conduction starting point selection step: determining the current conduction starting point at an arbitrary time; controlling a solid-state relay to conduct according to the power frequency; monitoring the speed of the PG motor; determining whether the current conduction starting point is a zero-crossing point based on the PG motor speed; if not, proceeding to the conduction starting point selection step. The zero-crossing detection method provided by the present invention replaces the zero-crossing detection circuit with a core software algorithm, effectively avoiding hardware circuit anomalies, significantly reducing design costs, and improving the reliability of PG motor control and the service life of the air conditioner.

Description

Technical Field

[0001] The present invention belongs to the field of motors, and in particular relates to a zero-crossing detection method, a detection system, a PG motor and an air conditioner. Background Art

[0002] PG motor is a kind of motor that controls the motor speed by controlling the conduction time of solid-state relay. Because PG motor is inexpensive on the market, it is widely used in air conditioner fans.

[0003] The circuit modules used in the air-conditioning control PG motors currently on the market mainly consist of a solid-state relay control circuit, a zero-crossing detection circuit, a motor speed feedback circuit, and an MCU centralized control circuit. Among them, the zero-crossing detection circuit plays a very important role. It can detect the zero-crossing point of the zero-live wire, thereby driving the conduction duration of the solid-state relay. If the zero-crossing detection circuit is abnormal, it will cause the entire PG motor to operate abnormally, resulting in the air conditioner being unusable; and if the zero-crossing detection error is large, it will also cause motor control abnormalities. The zero-crossing detection circuit is greatly affected by the power supply quality. In addition, the design cost of the zero-crossing detection circuit is also high, and the higher the detection accuracy, the higher the circuit cost. Summary of the Invention

[0004] In view of this, the present invention discloses a zero-crossing detection method, a detection system, a PG motor and an air conditioner, which are used to solve the problems of low stability and high cost of existing zero-crossing detection.

[0005] To solve the above technical problems, the first aspect of the present invention provides a zero-crossing detection method for a PG motor provided with a solid-state relay. The zero-crossing detection method includes:

[0006] Determine the power frequency of the current power supply;

[0007] Executing a conduction starting point selection step, executing a conduction node selection step to determine a current conduction starting point with any time as a starting point;

[0008] Control the solid-state relay to conduct according to the power frequency;

[0009] Monitor the speed of the PG motor;

[0010] Determine whether the current conduction starting point is a zero-crossing point based on the rotational speed of the PG motor; if not, go to the conduction starting point selection step.

[0011] Further optionally, determining whether the current conduction starting point is a zero-crossing point according to the rotation speed of the PG motor includes:

[0012] Determine whether the rotation speed of the PG motor is less than or equal to a first preset rotation speed;

[0013] If so, the current conduction starting point is determined to be the zero-crossing point.

[0014] Further optionally, when the rotation speed of the PG motor is greater than the first preset rotation speed, determining whether the current conduction starting point is a zero-crossing point according to the rotation speed of the PG motor further includes:

[0015] Determine whether the rotation speed of the PG motor is greater than a second preset rotation speed;

[0016] If so, the current conduction starting point is determined to be the zero-crossing point;

[0017] The first preset speed is smaller than the second preset speed.

[0018] Further optionally, the current conduction starting point is determined using the following formula:

[0019] t 当前 =t a +(k-1)×Δt1;

[0020] Among them, t 当前 represents the current conduction starting point, ta represents any time, Δt1 represents the first preset increment, and k represents the number of selections.

[0021] Further optionally, if the zero-crossing point is still not determined when the solid-state relay is controlled to be turned on at the zero-crossing period corresponding to the power frequency of the current power supply for the k-1th time, the step of selecting the conduction node is returned to the Kth time;

[0022] When the conduction node selection step is executed for the Kth time, the current conduction starting point t 当前 is: t 当前 =t a +(k-1)×Δt1;

[0023] Until it is determined that the current conduction starting point is the zero crossing point.

[0024] Further optionally, determining the power frequency of the current power supply includes:

[0025] Executing a zero-crossing cycle selection step: selecting a preset zero-crossing cycle from a plurality of preset zero-crossing cycles as a current zero-crossing cycle;

[0026] Control the solid-state relay to conduct at the current zero-crossing cycle;

[0027] According to the speed of the PG motor, it is determined whether the power frequency corresponding to the current zero-crossing cycle is the power frequency of the current power supply; if not, the process goes to the zero-crossing cycle selection step, selects an unselected preset zero-crossing cycle as the current zero-crossing cycle, and continues to determine the power frequency step.

[0028] Further optionally, judging whether the power frequency corresponding to the zero-crossing period is the power frequency of the current power supply according to the rotation speed of the PG motor includes:

[0029] Calculate the speed fluctuation error based on the speed of the PG motor;

[0030] determining whether the fluctuation error is less than a third preset speed;

[0031] If so, it is determined that the power frequency corresponding to the current zero-crossing period is the power frequency of the current power supply.

[0032] Further optionally, when it is determined that the power frequency corresponding to each of the plurality of preset zero-crossing periods is not the power frequency of the current power supply, the zero-crossing detection method further includes:

[0033] Execute the zero-crossing cycle adjustment step: determine a new current zero-crossing cycle based on the preset zero-crossing cycle; control the solid-state relay to conduct at the new current preset zero-crossing cycle;

[0034] Monitor the speed of the PG motor;

[0035] According to the rotation speed of the PG motor, it is determined whether the power frequency corresponding to the new current zero-crossing period is the power frequency of the current power supply; if not, the process proceeds to the zero-crossing period adjustment step.

[0036] Further optionally, the new current zero-crossing period is determined based on the preset zero-crossing period, and the new current zero-crossing period is determined using the following formula:

[0037] T 当前 =T 预设 +J×Δt2;

[0038] Among them, T 当前 Indicates the new current zero-crossing period, T 预设 represents the preset zero-crossing period, Δt2 represents the second preset increment, and J represents the number of adjustments.

[0039] A second aspect of the present invention provides a zero-crossing detection system for a PG motor, which includes one or more processors and a non-temporary computer-readable storage medium storing program instructions. When the one or more processors execute the program instructions, the one or more processors are used to implement any one of the zero-crossing detection methods of the first aspect.

[0040] Further optionally, the zero-crossing detection system includes a solid-state relay conduction control circuit and a PG motor speed detection circuit, the solid-state relay conduction control circuit is used to control the solid-state relay to conduct, and the PG motor speed detection circuit is used to detect the motor speed.

[0041] A third aspect of the present invention provides a PG motor, which adopts any method of the first aspect, or includes any zero-crossing detection system of the second aspect.

[0042] A fourth aspect of the present invention provides an air conditioner, which adopts the PG motor of the third aspect, or adopts any zero-crossing detection method of the first aspect, or includes any zero-crossing detection system of the second aspect.

[0043] After adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0044] The present invention proposes a PG motor control method without zero-crossing detection. By replacing the zero-crossing detection circuit with a core software algorithm, hardware circuit abnormalities can be effectively avoided, design costs can be greatly reduced, and the reliability of PG motor control and the service life of the air conditioner can be improved.

[0045] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The accompanying drawings are part of the present invention and are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention, but do not constitute an undue limitation of the present invention. Obviously, the drawings described below are only some embodiments. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without inventive effort. In the accompanying drawings:

[0047] Figure 1a It is a system framework diagram of an existing zero-crossing detection circuit.

[0048] Figure 1b A schematic diagram of a system framework of a zero-crossing detection system according to an embodiment of the present invention is provided.

[0049] Figure 2 2 is a schematic diagram of zero-crossing signal analysis according to an embodiment of the present invention.

[0050] Figure 3 4 is a flow chart of a zero-crossing detection method according to an embodiment of the present invention.

[0051] Figure 4 4 is a flow chart of a zero-crossing detection method according to an embodiment of the present invention.

[0052] Figure 5 4 is a flow chart of a zero-crossing detection method according to an embodiment of the present invention.

[0053] Figure 6 4 is a flow chart of a zero-crossing detection method according to an embodiment of the present invention.

[0054] Figure 7 4 is a flow chart of a zero-crossing detection method according to an embodiment of the present invention.

[0055] It should be noted that these drawings and textual descriptions are not intended to limit the conceptual scope of the present invention in any way, but rather to illustrate the concept of the present invention for those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0056] In the description of the present invention, it should be noted that the terms "inside" and "outside" etc. indicating orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the system or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0057] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connected," "in contact," and "connected" should be understood broadly. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; and direct or indirect connections through an intermediary. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0058] The zero-crossing detection circuit is a very important step in PG motor control. However, the zero-crossing detection circuit is also susceptible to interference, and it requires increased design costs to improve accuracy. To this end, a first embodiment of the present invention provides a zero-crossing detection method for a PG motor.

[0059] Figure 1a It is a system framework diagram of an existing zero-crossing detection circuit. Figure 1b According to one embodiment of the present invention, a schematic diagram of a zero-crossing detection system is provided. Figure 1a 、 1b As shown, this embodiment removes the zero-crossing detection circuit module from the existing mature solution and adds a software algorithm to identify the zero point of the zero-live line. To further explain the technical solution of the present invention, we must first understand the following Figure 1a 、 Figure 1b The solid-state relay control circuit mainly controls the output of the PG motor. The solid-state relay has a characteristic that once it is turned on, it will automatically shut down at the power zero point. The speed feedback detection circuit mainly detects the speed of the PG motor and can calculate the current real-time speed value through the main control MCU.

[0060] It should also be noted that there are generally two power supply frequencies in the world: 50 Hz and 60 Hz. For a 50 Hz power supply, the interval between each zero point is 10 ms, while for a 60 Hz power supply, the interval between each zero point is 8.33 ms. These two power supply frequencies are referred to as standard power supply frequencies. The power supply frequencies in this embodiment include but are not limited to the above two power supply frequencies.

[0061] The power supply's zero-crossing point and frequency are crucial for controlling PG motors. Since this embodiment lacks a zero-crossing detection circuit, determining the power supply's frequency and zero-crossing point through hardware circuitry is impossible. Instead, this embodiment primarily uses an analog algorithm to estimate the power supply's frequency and zero-crossing point using the PG motor's existing control circuitry.

[0062] The PG motor control method according to an embodiment of the present invention is described below with reference to the accompanying drawings.

[0063] Combine Figure 3 Flow chart of the present invention, the zero-crossing detection method of this embodiment includes:

[0064] S0, determines the power frequency of the current power supply.

[0065] Execute the conduction starting point selection step S1: S1, determine the current conduction starting point with any time as the starting point.

[0066] Because there is no hardware support, it is impossible to determine the current power zero point, so we can only randomly select the zero point at any time t a Turn on the solid state relay.

[0067] S2 controls the solid-state relay to conduct according to the power supply frequency.

[0068] In this embodiment, the current power supply frequency (codenamed f) is first determined, and then the power supply zero point (i.e., the zero-crossing point) is determined, so that the PG motor can be controlled. After the power supply frequency is determined, the zero-crossing period corresponding to the power supply frequency can be calculated based on the relationship between frequency and period.

[0069] S3, monitoring the speed of the PG motor; the speed feedback circuit can be used to monitor the speed of the PG motor in real time or at regular intervals, which can be recorded as S i , i=1, 2, 3...n, n>5.

[0070] S4, judging whether the current conduction starting point is a zero-crossing point according to the rotation speed of the PG motor; if not, going to step S1 of selecting the conduction starting point.

[0071] Specifically, after the power frequency f is locked, the power zero point needs to be found, such as Figure 2 As shown, t0, t1, t2, and t3 are all zero points, and t a For any time, t bis the conduction time of the next cycle, t c is the actual conduction moment, and the zero point interval period (i.e. zero crossing period) is Taking the current power frequency of 50HZ as an example, the zero-crossing period is 10ms. Figure 2 As shown, t a Starting at the specified time, the solid-state relay is controlled to conduct with a 10ms cycle. During this conduction, the motor speed is detected via the speed feedback circuit. If the speed meets the judgment criteria, the current conduction starting point is determined to be the zero crossing point of the power supply. If the speed does not meet the judgment criteria, the process proceeds to the conduction starting point selection step. The current conduction starting point is determined at any time, forming a loop until the current zero crossing point of the power supply is found.

[0072] Further optionally, combined with Figure 4 Flow chart of the process, step S4 includes S41 to S42, wherein:

[0073] S41, determining whether the rotation speed of the PG motor is less than or equal to a first preset rotation speed; if so, executing S42;

[0074] S42, determining that the current conduction starting point is the zero-crossing point.

[0075] Since the solid-state relay automatically shuts off at the power supply's zero-crossing point once it's turned on, the energy obtained by the PG motor is theoretically zero when the current conduction starting point is zero, and therefore its speed should theoretically be zero. However, considering the inertia of the motor during operation, the first preset speed (codenamed B) has a value range of greater than or equal to 0 and less than or equal to 150 rpm, with a preferred range of 0 to 50 rpm, specifically 10, 20, 30, 50, 100 rpm, etc. When the solid-state relay is turned on at any time, and during the conduction process, the PG motor's speed is detected to be less than or equal to the first preset speed, it can be determined that the current conduction starting point is the power supply's zero-crossing point.

[0076] Further optionally, combined with Figure 4 Flow chart of the invention, when the speed of the PG motor is greater than the first preset speed, the zero-crossing detection method further includes S43:

[0077] S43, determining whether the rotation speed of the PG motor is greater than a second preset rotation speed; if so, executing S42;

[0078] S42, determining that the current conduction starting point is a zero-crossing point;

[0079] The first preset speed is smaller than the second preset speed.

[0080] Specifically, since the solid-state relay has the characteristic of being non-conductive to the left of the zero crossing point and fully conductive to the right of the zero crossing point, if the current conduction starting point exceeds the zero crossing point, the solid-state relay will be fully conductive and the speed will be very high. Therefore, the second preset speed (codenamed C) should be much greater than the first preset speed B. In this embodiment, the value range of the second preset speed C is 600 rpm to 1300 rpm, with a preferred value of 1000 rpm. When the solid-state relay is turned on at any time, during its conduction process, if the real-time speed value of the PG motor is detected to be greater than the second preset speed, it can be determined that the current conduction starting point is the zero crossing point of the power supply.

[0081] Further optionally, the current conduction starting point is determined by using the following formula:

[0082] t 当前 =t a +(k-1)×Δt1;

[0083] Among them, t 当前 represents the current conduction starting point, ta represents the arbitrary time, Δt1 represents the first preset increment, and k represents the number of selections.

[0084] Further optionally, if the zero-crossing point is still not determined when the solid-state relay is controlled to be turned on at the zero-crossing period corresponding to the power frequency of the current power supply for the k-1th time, the step of selecting the conduction node is returned to the Kth time;

[0085] When the conduction node selection step is executed for the Kth time, the current conduction starting point t 当前 is: t 当前 =t a +(k-1)×Δt1;

[0086] Until it is determined that the current conduction starting point is the zero crossing point. Specifically, if the speed is greater than the first preset speed B and less than or equal to the second preset speed C, then the solid-state relay is controlled to conduct with (ta+Δt1) as the starting point, wherein the value range of Δt1 is 0.05~0.2ms, and the typical value is 0.1ms. If the detected real-time speed value still satisfies the condition that it is greater than the first preset speed B and less than or equal to the second preset speed C, then the new conduction starting point is determined with Δt1 as the increment, and the new conduction starting point is (ta+Δt1+Δt1), and the solid-state relay is controlled to conduct. Next, as long as the detected real-time speed value still satisfies the condition that it is greater than the first preset speed B and less than or equal to the second preset speed C, it continues to conduct with Δt1 as the increment until the speed value satisfies ≤B or >C (considering that the incremental value exceeds the zero crossing point, then full conduction will occur and the speed will be very high). At this time, it proves that the current conduction starting point has reached the zero crossing point of the power supply.

[0087] Further optionally, combined with Figure 5Flow chart of FIG. 1 , S0 includes steps 10 to 13, wherein:

[0088] Executing the zero-crossing cycle selection step 10: selecting an unselected preset zero-crossing cycle from a plurality of preset zero-crossing cycles as the zero-crossing cycle;

[0089] Step 11, controlling the solid-state relay to conduct at a zero-crossing period;

[0090] Step 12: Monitor the speed of the PG motor; this can be expressed as S' i , i=1, 2, 3...n, n>5;

[0091] Step 13, judging whether the power frequency corresponding to the zero-crossing period is the power frequency of the current power supply according to the speed of the PG motor; if not, go to the zero-crossing period selection step S10, select an unselected preset zero-crossing period as the current zero-crossing period to continue the power frequency determination step; if so, execute the conduction starting point selection step S1.

[0092] Specifically, after the air conditioner is powered on for the first time, the solid-state relay is turned on randomly at any time, such as Figure 2 As shown, taking any time ta as the starting point, the motor is turned on at any preset zero-crossing cycle in a plurality of preset zero-crossing cycles, and the speed feedback circuit is used to detect the speed value S' of the motor when the motor is turned on. i , and determines whether it meets the power supply frequency determination criteria. If the motor speed monitoring value meets this criteria, the power supply frequency corresponding to the currently selected preset zero-crossing period is determined to be the current power supply frequency. If not, the process proceeds to the zero-crossing period selection step. An unselected preset zero-crossing period is selected as the zero-crossing period, and motor speed monitoring continues. If the motor speed monitoring value still does not meet this criteria, the process proceeds to the zero-crossing period selection step, repeating the detection cycle until the current power supply frequency is determined.

[0093] Further optionally, the plurality of preset zero-crossing periods include a first preset zero-crossing period and a second preset zero-crossing period. In this embodiment, the first preset zero-crossing period is 10 ms, corresponding to a power supply frequency of 50 Hz, and the second preset zero-crossing period is 8.33 ms, corresponding to a power supply frequency of 60 Hz.

[0094] It can be understood that when determining the power frequency of the current power supply, the solid-state relay can be turned on with either of the two preset zero-crossing cycles mentioned above. If this preset zero-crossing cycle does not meet the requirements, the solid-state relay can be turned on with another preset zero-crossing cycle.

[0095] Further optionally, combined with Figure 6 Flow chart of the process, step 13 includes steps 131 to 133, wherein:

[0096] Step 131: Calculate the fluctuation error of the rotational speed based on the rotational speed of the PG motor.

[0097] Step 132: Determine whether the fluctuation error is less than the third preset rotational speed; if so, execute S0133.

[0098] Step 133: Then determine that the power frequency corresponding to the current zero-crossing period is the power frequency of the current power supply.

[0099] Specifically, after the air conditioner is powered on and starts up for the first time, first randomly turn on the solid-state relay at any moment. As Figure 2 shown, starting from any moment t a moment, turn on with a period of 10 ms (corresponding power frequency is 50 Hz). When turning on, detect the rotational speed value of the motor through the rotational speed feedback circuit and record it as S′ i , i = 1, 2, 3…n, n > 5, and calculate the fluctuation error ΔS of the real-time rotational speed value, ΔS = |S′ i- S′ i-1 |.

[0100] If ΔS < A (A represents the third preset rotational speed, and the value range of A is 5 - 15 revolutions per minute, with a typical value of 10 revolutions per minute), it proves that the energy value turned on in each period is the same, indicating that the current turn-on period and the power frequency match, and the power frequency can be locked at 50 Hz.

[0101] If the fluctuation error ΔS of the real-time rotational speed value ≥ A, it proves that the energy value turned on in each period is different, indicating that the current turn-on period and the power frequency are out of sync, and the power frequency is not 50 Hz. Then switch the turn-on period to 8.33 ms, that is, turn on with a period of 8.33 ms. When turning on, detect the real-time rotational speed value of the motor through the rotational speed feedback circuit. If the fluctuation error of the real-time rotational speed value is less than the third preset rotational speed, it proves that the energy value turned on in each period is the same, indicating that this turn-on period and the power frequency match, and the power frequency can be locked at 60 Hz.

[0102] Further optionally, if during the process of turning on with a period of 8.33 ms, the fluctuation error ΔS of the real-time rotational speed value ≥ A, it proves that the energy value turned on in each period is different, indicating that this turn-on period and the power frequency are out of sync, and the power frequency is not 60 Hz. Then it can be determined that the power frequency of the current power supply is not the standard frequency, but the deviation from the standard frequency is not too large. The power frequency can be fine-tuned by adjusting the zero-crossing period and turn on the solid-state relay with the new current zero-crossing period, and finally confirm that the power frequency is f (Hz).

[0103] Specifically, in combination with Figure 7Flow chart, when it is determined that the power frequency corresponding to each of the plurality of preset zero-crossing periods is not the power frequency of the current power supply, S0 further includes steps 14 to 17, wherein:

[0104] Execute zero-crossing period adjustment step 14: determine a new current zero-crossing period based on the preset zero-crossing period;

[0105] Step 15, controlling the solid-state relay to conduct with the new current zero-crossing period;

[0106] Step 16, monitoring the speed of the PG motor;

[0107] Step 17, judging whether the power frequency corresponding to the new current zero-crossing period is the power frequency of the current power supply according to the speed of the PG motor; if not, go to step 14 for adjusting the zero-crossing period; if so, execute step S1 for selecting the conduction starting point.

[0108] By fine-tuning the preset zero-crossing period, the new current zero-crossing period is determined, and then the speed monitoring value of the PG motor is judged in the same way. If the speed monitoring value still does not meet the third preset speed, the zero-crossing period adjustment step is performed to form a cyclic detection until the speed monitoring value meets the second preset condition, thereby locking the power frequency of the current power supply.

[0109] Further optionally, the new current zero-crossing period is determined using the following formula:

[0110] T 当前 =T 预设 +J×Δt2;

[0111] Among them, T 当前 Represents the new current zero-crossing period, T 预设 represents the preset zero-crossing period, Δt2 represents the second preset increment, and J represents the number of adjustments.

[0112] Specifically, using 8.33ms as an example, 0.1ms is added to 8.33ms, resulting in a solid-state relay on-state cycle of 8.43ms. During the on-state process, the PG motor speed is obtained. If the real-time fluctuation error of the speed monitoring value still does not meet the requirement of being less than the third preset speed, the preset zero-crossing period is adjusted by the second preset increment Δt2. That is, 0.1ms is added to 8.43ms, resulting in the solid-state relay on-state cycle of 8.53ms. This is repeated until the power supply frequency f is determined.

[0113] The zero-crossing detection method of this embodiment eliminates the need for a zero-crossing detection circuit, reducing design costs. Replacing the zero-crossing detection circuit with a core software algorithm prevents motor control anomalies caused by hardware circuit anomalies, significantly improving the reliability of PG motor control and the lifespan of the air conditioner. Furthermore, the use of a chopping control and speed detection algorithm enables accurate detection of power supply frequency and zero-crossing points, further enhancing the reliability of PG motor control and the lifespan of the air conditioner.

[0114] The second aspect embodiment of the present invention also provides a motor zero-crossing detection system, which includes one or more processors and a non-temporary computer-readable storage medium storing program instructions. When the one or more processors execute the program instructions, the one or more processors are used to implement the zero-crossing detection method of any one of the first aspect embodiments.

[0115] The third aspect of the present invention further provides a motor, which adopts the zero-crossing detection method of any one of the first aspect embodiments, or includes the zero-crossing detection system of any one of the second aspect embodiments.

[0116] The fourth aspect of the present invention further provides an air conditioner, which adopts the PG motor of the third aspect, or adopts any one of the zero-crossing detection methods of the first aspect, or includes the zero-crossing detection system of the second aspect.

[0117] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, i.e., they may be located in one place or distributed across multiple network units. Some or all of the modules may be selected as needed to achieve the objectives of the present embodiment. Persons of ordinary skill in the art will be able to understand and implement the present invention without inventive effort.

[0118] Through the description of the above embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus a necessary general hardware platform, or of course, by hardware. Based on this understanding, the essence of the above technical solution or the part that contributes to the existing technology can be embodied in the form of a software product. The computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a magnetic disk, an optical disk, etc., and includes a number of instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or certain parts of the embodiments.

[0119] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any technician familiar with this patent can make slight changes or modifications to equivalent embodiments using the above technical content without departing from the scope of the technical solution of the present invention. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the solution of the present invention.

Claims

1. A zero-crossing detection method for a PG motor equipped with a solid-state relay, characterized in that: The zero-crossing detection method comprises: Determine the power frequency of the current power supply; Executing a conduction starting point selection step, wherein the conducting starting point selection step is to determine a current conduction starting point with any time as a starting point; Controlling the solid-state relay to conduct according to the power supply frequency; Monitoring the rotational speed of the PG motor; Determine whether the current conduction starting point is a zero-crossing point according to the rotation speed of the PG motor; if not, proceed to the conduction starting point selection step; in: Determining the power frequency of the current power supply includes: Executing a zero-crossing cycle selection step: selecting a preset zero-crossing cycle from a plurality of preset zero-crossing cycles as the zero-crossing cycle; Controlling the solid-state relay to conduct during the current zero-crossing period; Monitoring the rotational speed of the PG motor; Determine whether the power frequency corresponding to the current zero-crossing period is the power frequency of the current power supply according to the rotation speed of the PG motor; if not, proceed to the zero-crossing period selection step, select an unselected preset zero-crossing period as the current zero-crossing period, and continue to determine the power frequency step; The determining, based on the rotational speed of the PG motor, whether the power frequency corresponding to the zero-crossing period is the power frequency of the current power supply includes: Calculating a speed fluctuation error according to the speed of the PG motor; Determining whether the fluctuation error is less than a third preset speed; If yes, determining that the power frequency corresponding to the current zero-crossing period is the power frequency of the current power supply; The step of selecting a conduction starting point determines the current conduction starting point by taking any time as the starting point and adopting the following formula to determine the current conduction starting point: t 当前 =t a +(k-1)×Δt1; Among them, t 当前 represents the current conduction starting point, ta represents the arbitrary time, Δt1 represents the first preset increment, and k represents the number of selections; If the zero-crossing point is not determined when the solid-state relay is controlled to be turned on at the zero-crossing period corresponding to the power frequency of the current power supply for the k-1th time, the process returns to the K-th execution of the conduction starting point selection step until the current conduction starting point is determined to be the zero-crossing point.

2. The zero-crossing detection method according to claim 1, wherein The determining, based on the rotational speed of the PG motor, whether the current conduction starting point is a zero-crossing point includes: Determining whether the rotation speed of the PG motor is less than or equal to a first preset rotation speed; If so, the current conduction starting point is determined to be the zero-crossing point.

3. The zero-crossing detection method according to claim 2, wherein: When the rotation speed of the PG motor is greater than the first preset rotation speed, the step of determining whether the current conduction starting point is a zero-crossing point according to the rotation speed of the PG motor further includes: Determining whether the rotation speed of the PG motor is greater than a second preset rotation speed; If so, determining that the current conduction starting point is the zero-crossing point; Wherein, the first preset speed is smaller than the second preset speed.

4. The zero-crossing detection method according to any one of claims 1 to 3, wherein: When it is determined that the power frequency corresponding to each of the plurality of preset zero-crossing periods is not the power frequency of the current power supply, the zero-crossing detection method further includes: Executing a zero-crossing period adjustment step, wherein the step of adjusting the zero-crossing period determines a new current zero-crossing period based on the preset zero-crossing period; Controlling the solid-state relay to conduct with the new current zero-crossing period; Monitor the speed of the PG motor; Determine whether the power frequency corresponding to the new current zero-crossing period is the power frequency of the current power supply according to the rotation speed of the PG motor; if not, go to the zero-crossing period adjustment step.

5. The zero-crossing detection method according to claim 4, wherein: The new current zero-crossing period is determined based on the preset zero-crossing period using the following formula: T 当前 =T 预设 +J×Δt2; Among them, T 当前 Represents the new current zero-crossing period, T 预设 represents the preset zero-crossing period, Δt2 represents the second preset increment, and J represents the number of adjustments.

6. A zero-crossing detection system for a PG motor, characterized in that: It includes one or more processors and a non-transitory computer-readable storage medium storing program instructions. When the one or more processors execute the program instructions, the one or more processors are used to implement the zero-crossing detection method according to any one of claims 1 to 5.

7. A zero-crossing detection system according to claim 6, characterized in that: The zero-crossing detection system includes a solid-state relay conduction control circuit and a PG motor speed detection circuit. The solid-state relay conduction control circuit is used to control the solid-state relay to conduct, and the PG motor speed detection circuit is used to detect the motor speed.

8. A PG motor, characterized in that: It adopts the zero-crossing detection method according to any one of claims 1-5, or includes the zero-crossing detection system according to any one of claims 6-7.

9. An air conditioner, characterized in that: It adopts the PG motor described in claim 8, or adopts the zero-crossing detection method described in any one of claims 1-6, or includes the zero-crossing detection system described in any one of claims 7-8.

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