A self-correction method for relay zero-crossing drive

Abstract

The present invention proposes a self-calibration method for relay zero-crossing drive, comprising: starting from the rising edge of a mains power conversion square wave and after a currently set delay time, changing the control level of the relay; recording the moment when the feedback signal experiences level fluctuations based on the level relationship between the mains power conversion square wave and the feedback signal of the relay to the control level; calculating a time correction amount for the relay zero-crossing drive in conjunction with the self-calibration period Tz of the relay zero-crossing drive, and adjusting the delay time for the next zero-crossing drive based on the time correction amount. The present invention solves the technical problem of increased voltage difference in the relay zero-crossing drive caused by different relay batches, relay aging, voltage fluctuations, frequency fluctuations, etc., thereby achieving the function of quickly realizing the opening and closing of the relay near zero point in different frequency AC power environments with only low chip resources, thereby improving the service life of the relay.

Description

Technical Field

[0001] The invention belongs to the technical field of relay control, and in particular relates to a self-correction method for zero-crossing drive of a relay. Background Art

[0002] When a relay is applied to an AC system, the contacts are the most important component of the relay. To avoid damage to the equipment caused by the surge current generated when the contacts are closed, it is usually necessary to ensure that the relay contacts are closed when the AC power passes through zero, thereby maximizing the safety of the relay equipment.

[0003] To achieve zero-crossing drive of the relay, existing solutions mostly use relatively complex peripheral circuits for zero-crossing detection. Setting up zero-crossing detection in the periphery not only increases circuit costs, but also brings the risk of increasing the zero-crossing drive voltage difference of the relay due to unpredictable factors such as different batches of relays, relay aging, and voltage and frequency fluctuations of the mains power, thereby reducing the reliability of the relay circuit. Summary of the Invention

[0004] In order to solve the shortcomings and deficiencies in the prior art, the present invention proposes a self-correction method for zero-crossing drive of a relay, comprising:

[0005] Starting from the rising edge of the mains conversion square wave, after the currently set delay time, the control level of the relay is changed;

[0006] According to the level relationship between the mains-converted square wave and the feedback signal of the relay for controlling the level, the moment when the feedback signal level fluctuates is recorded;

[0007] Combined with the self-correction period Tz of the relay zero-crossing drive, the time correction amount of the relay zero-crossing drive is calculated, and the delay time of the next zero-crossing drive is adjusted according to the time correction amount.

[0008] Optionally, recording the moment when the level of the feedback signal fluctuates according to the level relationship between the mains-converted square wave and the feedback signal of the relay control level includes:

[0009] If the feedback signal and the AC power conversion square wave have the same level, record the moment when the relay feedback signal is pulled low;

[0010] If the levels of the feedback signal and the AC power conversion square wave are opposite, record the moments when the relay's feedback signal is pulled low and high respectively.

[0011] Optionally, the self-correction period Tz of the zero-crossing drive of the relay is combined to calculate the time correction amount of the zero-crossing drive of the relay, and the delay time of the next zero-crossing drive is adjusted according to the time correction amount, including:

[0012] If the feedback signal and the AC power conversion square wave have the same level, the time between the rising edge of the AC power conversion square wave and the low edge of the relay feedback signal is recorded as the first time Ta;

[0013] Calculate the delay time of the next zero-crossing drive: Ton = Ton + (Tz - Ta), where (Tz - Ta) is the time correction amount for the zero-crossing drive of the relay.

[0014] Optionally, the self-correction period Tz of the zero-crossing drive of the relay is combined to calculate the time correction amount of the zero-crossing drive of the relay, and the delay time of the next zero-crossing drive is adjusted according to the time correction amount, including:

[0015] If the levels of the feedback signal and the mains conversion square wave are opposite, the time from when the control pin is changed to when the feedback signal of the relay is pulled low is recorded as the second time Tc, and the time from when the feedback signal of the relay is pulled low to when it is pulled high is recorded as the third time Td;

[0016] Calculate the delay time of the next zero-crossing drive Toff = Toff-(Tc-Tz-Td), (Tc-Tz-Td) is the time correction amount of the relay zero-crossing drive.

[0017] Optionally, changing the level of the control pin of the relay includes:

[0018] When the relay changes from open to closed, the control pin level of the relay is pulled high;

[0019] When the relay switches from closed to open, the control pin level of the relay is pulled low.

[0020] Optionally, the relay is connected to a live wire, which is also connected to a main control chip;

[0021] The internal timer of the main control chip is provided with a counting variable C1 and a counting variable C2, and the counting variable C1 and the counting variable C2 start timing from the rising edge of the mains power conversion square wave;

[0022] The main control chip records the self-correction cycle through the counting variable C1;

[0023] The main control chip records the moment when the level fluctuation of the feedback signal occurs through the counting variable C2.

[0024] Optionally, the main control chip records the moment when the feedback signal level fluctuates through the counting variable C2, including: if the level of the feedback signal of the relay is opposite to that of the AC power conversion square wave, when the level of the control pin of the relay changes and when the level of the feedback signal of the relay fluctuates, the count value of the counting variable C2 is stored and then cleared to zero, and counted again.

[0025] Optionally, the feedback signal when the relay is closed is opposite to the level of the mains-converted square wave, and the feedback signal when the relay is open is the same as the level of the mains-converted square wave.

[0026] Optionally, the Tz when the relay is switched from closed to open is increased by a rising edge period of the mains conversion square wave compared to the Tz when the relay is switched from open to closed.

[0027] Optionally, when the relay is self-calibrated for the first time, the currently set delay time is a preset default delay time.

[0028] The beneficial effects brought about by the technical solution provided by the present invention are:

[0029] The present invention utilizes a master control chip to perform zero-crossing detection, thereby optimizing the zero-crossing detection circuit and reducing the hardware cost of the drive circuit. Furthermore, the proposed control process for relay closing and opening utilizes a zero-crossing signal to calculate the next action delay after each relay action. This addresses the technical issue of increased relay zero-crossing drive voltage differences due to factors such as different relay batches, relay aging, voltage fluctuations, and frequency fluctuations. This allows for rapid switching of the relay near zero in AC power environments of varying frequencies, requiring only relatively low chip resources, thereby extending the relay's service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solution of the present invention, the following is a brief introduction to the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0031] Figure 1 A schematic flow chart of a self-calibration method for zero-crossing drive of a relay proposed in an embodiment of the present invention;

[0032] Figure 2 This is the relay circuit structure diagram of the existing zero-crossing drive solution;

[0033] Figure 3 1 is a structural diagram of a relay circuit according to an embodiment of the present invention;

[0034] Figure 4 Schematic diagram of signal changes during the relay closing process in an embodiment of the present invention;

[0035] Figure 5 Schematic diagram of the details of the feedback signal changes during the relay closing process;

[0036] Figure 6Schematic diagram of signal changes during the relay disconnection process in an embodiment of the present invention;

[0037] Figure 7 Schematic diagram of the details of the feedback signal changes during the relay disconnection process. DETAILED DESCRIPTION

[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0039] The terms "first," "second," "third," "fourth," and so forth (if any) in the description and claims of the present invention and the accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a particular order or sequential sequence. It should be understood that the terms used in this manner are interchangeable where appropriate, so that the embodiments of the present invention described herein can be implemented in sequences other than those illustrated or described herein.

[0040] It should be understood that in various embodiments of the present invention, the size of the sequence number of each process does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0041] It should be understood that in the present invention, "include" and "have" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products or apparatuses.

[0042] It should be understood that in the present invention, "multiple" refers to two or more. "And / or" is only a description of the association relationship of associated objects, indicating that three relationships can exist. For example, and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the previous and next associated objects are in an "or" relationship. "Contains A, B and C", "Contains A, B, C" means that A, B, and C are all included, "Contains A, B or C" means that one of A, B, and C is included, and "Contains A, B and / or C" means that any one, any two, or any three of A, B, and C are included.

[0043] It should be understood that, in the present invention, "B corresponding to A," "B corresponding to A," "A corresponds to B," or "B corresponds to A" means that B is associated with A and B can be determined based on A. Determining B based on A does not mean determining B based solely on A; B can also be determined based on A and / or other information. A and B match when the similarity between A and B is greater than or equal to a preset threshold.

[0044] Depending on the context, "if" as used herein may be interpreted as "when" or "when" or "in response to determining" or "in response to detecting."

[0045] The following specific embodiments are used to describe the technical solution of the present invention in detail. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments.

[0046] like Figure 1 As shown, this embodiment proposes a self-correction method for zero-crossing drive of a relay, including:

[0047] S1: Starting from the rising edge of the mains conversion square wave, after the currently set delay time, the control level of the relay is changed;

[0048] S2: Based on the level relationship between the mains-converted square wave and the feedback signal of the relay control level, record the moment when the feedback signal level fluctuates;

[0049] S3: Calculate the time correction amount of the relay zero-crossing drive in combination with the self-correction period Tz of the relay zero-crossing drive, and adjust the delay time of the next zero-crossing drive according to the time correction amount.

[0050] In order to realize the zero-crossing drive of the relay, the existing method usually sets a relatively complex peripheral circuit to provide the zero-point detection function. The relay circuit is as follows: Figure 2 As shown, the relay is connected between the AC live wire and the AC neutral wire, and a voltage divider circuit and a zero-crossing detection circuit are connected in sequence between the relay and the main control chip.

[0051] In this embodiment, the peripheral circuit for zero-crossing detection is no longer provided, and the relay circuit is as follows. Figure 3As shown, the main control chip analyzes the rising edge of the mains conversion square wave by collecting the electrical signal on the voltage divider circuit, and also realizes the self-correction of the zero-crossing drive by collecting the feedback signal of the relay. Without setting up a peripheral circuit, the time difference required for the relay to open and close under different frequencies and voltages can be calculated by the internal timer, thereby making the loop structure simpler and reducing the loop cost. At the same time, when correcting the zero-crossing drive of the relay, this embodiment combines the mains waveform and the feedback waveform of the relay, and calculates the next action delay time in combination with the zero-crossing signal after each relay action. Therefore, it can solve the technical problem of the relay zero-crossing drive voltage difference becoming larger due to reasons such as different relay batches, relay aging, voltage fluctuation, frequency fluctuation, etc., and then realize the function of quickly realizing the opening and closing of the relay near zero point under different frequency AC power environments with only lower chip resources, thereby improving the service life of the relay.

[0052] In this embodiment, the rising edge of the mains conversion square wave (ZVP) is used as the interrupt edge of the zero-crossing drive. The rising edge of ZVP refers to the zero point where the mains power changes from the negative half axis to the positive half axis. A ZVP waveform is a complete square wave containing high and low levels, that is, a complete mains waveform cycle.

[0053] In this embodiment, the self-calibration of the relay zero-crossing detection includes a relay closing control process and a relay opening control process. When the relay switches from opening to closing, the relay control pin level is pulled high; when the relay switches from closing to opening, the relay control pin level is pulled low.

[0054] In this embodiment, based on the level relationship between the feedback signal of the relay and the mains conversion square wave, recording the moment when the level fluctuation of the feedback signal occurs includes:

[0055] If the relay feedback signal is at the same level as the AC power conversion square wave, record the moment when the relay feedback signal is pulled low;

[0056] If the relay's feedback signal and the AC power conversion square wave have opposite levels, record the moments when the relay's feedback signal is pulled low and high respectively.

[0057] In this embodiment, the feedback signal of the relay when closed is opposite in level to the mains-converted square wave, and the feedback signal of the relay when open is the same in level as the mains-converted square wave. Therefore, in this embodiment, when the relay switches from open to closed, i.e., during the relay closing control process, the moment when the relay feedback signal goes low is recorded; when the relay switches from closed to open, i.e., during the relay opening control process, the moment when the relay feedback signal goes low and high is recorded, respectively.

[0058] In this embodiment, the calculation process of the time correction amount includes:

[0059] If the level of the relay's feedback signal is the same as the AC power conversion square wave, the time between the rising edge of the AC power conversion square wave and the relay's feedback signal being pulled low is recorded as the first time Ta; the delay time of the next zero-crossing drive is calculated as Ton = Ton + (Tz - Ta), where (Tz - Ta) is the time correction amount for the relay's zero-crossing drive.

[0060] If the level of the relay's feedback signal is opposite to that of the AC power conversion square wave, the time from when the control pin's level changes to when the relay's feedback signal is pulled low is recorded as the second time Tc, and the time from when the relay's feedback signal is pulled low to when it is pulled high is recorded as the third time Td; calculate the delay time Toff for the next zero-crossing drive as Toff = Toff - (Tc - Tz - Td), where (Tc - Tz - Td) is the time correction amount for the relay's zero-crossing drive.

[0061] In this embodiment, the relay is connected to the live wire, which is also connected to a main control chip;

[0062] The internal timer of the main control chip is provided with a counting variable C1 and a counting variable C2, and the counting variable C1 and the counting variable C2 start timing from the rising edge of the mains power conversion square wave;

[0063] The main control chip records the self-correction cycle through the counting variable C1;

[0064] The main control chip records the moment when the level fluctuation of the feedback signal occurs through the counting variable C2.

[0065] Specifically, the counting variable C1 stores the counting value as Tz record;

[0066] In the closing control process of the relay, the count value of the counting variable C2 is stored as Ta record;

[0067] In the disconnection control process of the relay, when the level of the control pin of the relay changes and when the level of the feedback signal of the relay fluctuates, the counting variable C2 is cleared and then counted again.

[0068] In this embodiment, the main control chip is set with two counting variables, so that only one internal timer is needed to meet the timing functions required in the closing control process and the opening control process. Therefore, chip resources can be saved to a certain extent, and even in the case of extreme lack of hardware conditions, self-correction of the relay zero-crossing drive can be achieved with smaller computing resource requirements.

[0069] Below through Figure 4-Figure 7 The signal level change diagram shown in FIG. 1 specifically illustrates the closing control process and the opening control process based on the counting mechanism of the main control chip.

[0070] The closed control process is as follows Figure 4 and Figure 5 As shown in the figure, the main control chip waits for the rising edge of ZVP, starts the internal timer at position ①, and counts the counter variables C1 and C2. It then waits for the currently set delay time, Ton, from position ①. At position ②, the main control chip pulls the relay control pin high to level H. If this is the first self-calibration, the delay time is the preset default delay time. It then waits for the feedback signal to drop to level L at position ③, recording the count value of counter variable C2 at this time as Ta. It then waits for the feedback signal to rise again at position ④. It then waits for the next rising edge of ZVP at position ⑤, recording the count value of counter variable C1 at this time as Tz, and shuts down the internal timer. At this point, the delay time for the relay to close is calculated as Ton = Ton + (Tz - Ta).

[0071] The above process shows that when the relay switches from open to closed, Tz is the total time between the two rising edges of the mains conversion square wave. This means that one self-calibration cycle requires two ZVP cycles to calculate. This calculated delay time brings the actual feedback point closer to the rising edge of the ZVP during the next relay closure. After one closure cycle, the next relay closure time and the zero-crossing voltage difference remain within ±25V.

[0072] It should be noted that Figure 5 It can be seen from the figure that when the feedback signal changes from position ③ to position ④, since ZVP is at a low level and the relay is connected to the live wire, it is difficult for the feedback signal to return to a high level again. The process of the feedback signal changing from position ③ to position ④ is slow and unreliable. Therefore, in this embodiment, Ta, which has a more stable time quantity, is used to calculate the delay time to ensure the accuracy of the self-calibration result.

[0073] The disconnection control process is as follows Figure 6 and Figure 7 As shown in the figure, the main control chip waits for a rising edge of ZVP. At position ①, it starts an internal timer and counts variables C1 and C2. It then waits for the currently set delay time from position ①. At position ②, the main control chip pulls the relay control pin to a low level, L. If this is the first self-calibration, the delay time is the preset default delay time. Simultaneously, variable C2 is cleared at position ② and counting restarts. When the feedback signal pulls low at position ③, the value of variable C2 at that time is recorded as Tc, and C2 is cleared again. When the feedback signal pulls high at position ④, the value of variable C2 at that time is recorded as Td. Then, it waits for the next rising edge of ZVP at position ⑤, records the value of variable C1 at that time as Tz, and shuts down the internal timer. At this point, the delay time for the relay to disconnect, Toff, is calculated as Toff - (Tc - Tz - Td).

[0074] The above process shows that when the relay switches from closed to open, Tz is the total time between the three rising edges of the mains conversion square wave. This means that one self-calibration cycle requires three ZVP cycles to calculate. Due to the characteristics of the relay's feedback signal, the calculated delay time brings the actual feedback point of the relay closer to the rising edge of the ZVP during the next closure. After four or five closures, the next relay closure time and the zero-crossing voltage differential remain within ±30V.

[0075] It should be noted that Figure 7 It can be seen that when the feedback signal changes from position ③ to position ④, since ZVP is at a high level and the relay is connected to the live wire, it is relatively easy for the feedback signal to return to a high level again. The process of the feedback signal changing from position ③ to position ④ is more reliable than the closed control process. Therefore, in this embodiment, the time quantities Tc and Td are used to calculate the delay time.

[0076] In addition, considering that the time it takes for the relay to switch from the closed state to the open state will fluctuate due to the size of the load, the Tz when the relay switches from closed to open is increased by one rising edge period of the mains conversion square wave compared to the Tz when the relay switches from open to closed. In this embodiment, to ensure measurement accuracy, the opening process period is changed from 2 ZVP periods to 3 ZVP periods.

[0077] The above-mentioned closing control process and opening control process eliminate the need to calibrate each relay product before leaving the factory. In addition, since the zero-crossing drive self-correction is performed by combining the square wave waveform of the mains power and the feedback signal waveform of the relay, it can cope with the closing time errors caused by relay batches, materials, and material aging.

[0078] The serial numbers in the above embodiments are for description only and do not represent the order of assembly or use of the components.

[0079] The above descriptions are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A self-calibration method for relay zero-crossing drive, characterized in that: The self-correction method comprises: Starting from the rising edge of the mains conversion square wave, after the currently set delay time, the control level of the relay is changed; According to the level relationship between the mains-converted square wave and the feedback signal of the relay for controlling the level, the moment when the feedback signal level fluctuates is recorded; Combined with the self-correction period Tz of the relay zero-crossing drive, the time correction amount of the relay zero-crossing drive is calculated, and the delay time of the next zero-crossing drive is adjusted according to the time correction amount; The relay is connected to the live wire, which is also connected to the main control chip; The internal timer of the main control chip is provided with a counting variable C1 and a counting variable C2, and the counting variable C1 and the counting variable C2 start timing from the rising edge of the mains power conversion square wave; The main control chip records the self-correction cycle through the counting variable C1; The main control chip records the moment when the feedback signal level fluctuates through the counting variable C2; The step of recording the moment when the level of the feedback signal fluctuates according to the level relationship between the mains conversion square wave and the feedback signal of the relay control level comprises: If the feedback signal and the AC power conversion square wave have the same level, record the moment when the relay feedback signal is pulled low; If the levels of the feedback signal and the AC power conversion square wave are opposite, record the moments when the relay feedback signal is pulled low and high respectively; The method combines the self-correction period Tz of the relay zero-crossing drive, calculates the time correction amount of the relay zero-crossing drive, and adjusts the delay time of the next zero-crossing drive according to the time correction amount, including: If the feedback signal and the AC power conversion square wave have the same level, the time between the rising edge of the AC power conversion square wave and the low edge of the relay feedback signal is recorded as the first time Ta; Calculate the delay time of the next zero-crossing drive Ton=Ton+(Tz-Ta), where (Tz-Ta) is the time correction amount for the zero-crossing drive of the relay. If the levels of the feedback signal and the mains conversion square wave are opposite, the time from when the control level changes to when the relay feedback signal is pulled low is recorded as the second time Tc, and the time from when the relay feedback signal is pulled low to when it is pulled high is recorded as the third time Td. Calculate the delay time of the next zero-crossing drive Toff = Toff-(Tc-Tz-Td), (Tc-Tz-Td) is the time correction amount of the relay zero-crossing drive.

2. A self-correction method for relay zero-crossing drive according to claim 1, characterized in that, Changing the control level of the relay includes: When the relay changes from open to closed, the control level of the relay is pulled up; When the relay changes from closed to open, the control level of the relay is pulled down.

3. A self-correction method for relay zero-crossing drive according to claim 1, characterized in that, The main control chip records the moment when the feedback signal level fluctuates through the counting variable C2, including: If the levels of the relay's feedback signal and the AC power conversion square wave are opposite, the counting variable C2 will be cleared and restarted when the relay's control level changes and the relay's feedback signal level fluctuates.

4. A self-correction method for relay zero-crossing drive according to claim 1, characterized in that, The feedback signal when the relay is closed is opposite to the level of the mains-converted square wave, and the feedback signal when the relay is open is the same as the level of the mains-converted square wave.

5. The self-correction method for zero-crossing drive of a relay according to claim 1, wherein: Compared with the Tz when the relay is switched from closed to open, the Tz when the relay is switched from open to closed increases the rising edge period of the mains conversion square wave.

6. A self-correction method for relay zero-crossing drive according to claim 1, characterized in that: When the relay is self-calibrated for the first time, the currently set delay time is the preset default delay time.

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