Relay zero-crossing switch control method and circuit

Abstract

The present invention discloses a relay zero-crossing switch control method and circuit, the method comprising: sampling the output voltage of an arc identification module to obtain N initial sampling data; wherein N is a positive integer; performing multiple decomposition processing on the N initial sampling data to obtain a decomposition result; obtaining a corrected current shut-off moment based on the decomposition result; verifying the corrected current shut-off moment to obtain a verification result; and determining the actual current shut-off moment based on the verification result. The technical solution of the present invention does not require sampling of current signals, but multiple decomposition of the waveform sampled by the arc identification module, and extracting characteristic parameters of the arc therefrom, and calculating the lead amount based on the characteristic parameters. After setting a reasonable characteristic parameter threshold, the calculation of the lead amount hardly requires iteration, and the zero-crossing switch can be quickly realized, further extending 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 relay zero-crossing switch control method and circuit. Background Art

[0002] In actual operation, if there is no special treatment, the relay will have a high probability of high voltage attraction or high current breaking process. Both of these situations will generate arcs. The high temperature generated by the arc has a great impact on the life of the relay contacts. Therefore, the arc extinguishing treatment of attraction and breaking is particularly important. If the relay breaks the alternating current, it will be much easier to extinguish the arc. This is because the alternating current has a zero-crossing point. When the current passes through zero, the arc will be temporarily extinguished. As long as it is not re-ignited in the next cycle, the arc can be extinguished naturally. Therefore, the arc maintenance time is generally short, and the intensity of the arc can be greatly reduced by using zero voltage opening and zero current closing technology.

[0003] The prior art has proposed adaptive or self-learning zero-crossing switching methods. However, these methods have the following problems: (1) Current sampling is required, and multiple iterations are required to achieve zero-crossing switching, which has a limited effect on improving the life of the relay; (2) Current signals need to be directly sampled, which is large in size, high in cost, and generates severe heat under high load; (3) If the current signal is not sampled, it is ineffective for non-resistive loads and has a narrow range of applications. Summary of the invention

[0004] The present invention aims to solve one of the technical problems in the related art at least to a certain extent. To this end, one object of the present invention is to provide a relay zero-crossing switch control method and circuit.

[0005] In order to solve the above technical problems, the embodiments of the present invention provide the following technical solutions:

[0006] A relay zero-crossing switch control method, comprising:

[0007] Sampling the output voltage of the arc identification module to obtain N initial sampling data, wherein N is a positive integer;

[0008] Perform multiple decomposition processes on the N initial sampling data to obtain decomposition results;

[0009] Acquire a corrected current shut-off time based on the decomposition result;

[0010] Verifying the correction current shut-off moment and obtaining a verification result;

[0011] Based on the verification result, the actual current shut-off time is determined.

[0012] Optionally, performing multiple decomposition processes on the N initial sampling data to obtain decomposition results includes:

[0013] Get the j-1th sampling data; where j is a positive integer;

[0014] Perform filtering processing on the j-1th sampling data based on a low-pass filter to obtain a jth low-pass filtering result; at the same time, perform filtering processing on the j-1th sampling data based on a high-pass filter to obtain a jth high-pass filtering result;

[0015] Down-sampling the j-th low-pass filtering result to obtain the j-th sampling data; at the same time, down-sampling the j-th high-pass filtering result to obtain the j-th high-pass down-sampling result;

[0016] Based on the first j high-pass downsampling results and the j-th sampling data, a decomposition result is obtained.

[0017] Optionally, the decomposition result is calculated based on the following formula:

[0018] x(n)=a j +d j +……+d 1

[0019] Among them, a j is the target low-frequency component; d j is the j-th high-pass downsampling result, 0<n≤N.

[0020] Optionally, acquiring the corrected current shut-off time based on the decomposition result includes:

[0021] Based on the first high-pass filtering result, the correction amount Δt of the first leading amount is calculated and obtained. 1 ;

[0022] The correction amount Δt based on the first advance amount 1 , obtain the corrected current cut-off time t;

[0023] Where t = t 1 -Δt 1 ;t 1 It is the preset current shut-off time.

[0024] Optionally, the correction amount Δt of the first leading amount is 1 Calculated by the following formula:

[0025]

[0026] Among them, T hf is a half period; floor() represents rounding; floor((M+N-1) / 2) is the length of the data of the first high-pass filtering result; i is the subscript with the highest amplitude of the first high-pass filtering result; M is the length of the high-pass filter and the low-pass filter.

[0027] Optionally, verifying the corrected current shut-off moment and obtaining a verification result includes:

[0028] Acquire k data points of the target low-frequency component and k down-sampled data of the initial sampled data; wherein k is a positive integer;

[0029] Acquire arc characteristic parameters based on the k data points of the target low-frequency component and the k down-sampled data of the initial sampling data;

[0030] Based on the arc characteristic parameters, the correction current cut-off moment is verified to obtain the verification result.

[0031] Optionally, the arc characteristic parameter is calculated by the following formula:

[0032]

[0033] Among them, a j (k) is the k data points of the target low-frequency component; x(k) is the k downsampled data of the initial sampling data.

[0034] Optionally, also include,

[0035] Get half period T hf ;

[0036] Calculate a second lead amount for the relay to be turned on based on voltage zero crossing;

[0037] Based on the half cycle and the second lead amount, adjusting the drive signal of the coil of the relay to obtain an actual drive signal;

[0038] The relay is turned on based on the actual driving signal.

[0039] Optionally, the half period T hf is the time difference between a rising edge and a falling edge adjacent to the sampling voltage zero-crossing signal;

[0040] Wherein, the sampled voltage is obtained based on a voltage detection module.

[0041] An embodiment of the present invention further provides a relay zero-crossing switch control circuit, comprising:

[0042] Relay;

[0043] an arc identification module, the arc identification module being coupled to a contact end of the relay;

[0044] A processing module is coupled to the arc identification module and the coil control module respectively; the coil control module is coupled to the coil end of the relay.

[0045] The embodiments of the present invention have the following technical effects:

[0046] The above technical solution of the present invention, 1) based on the voltage zero-crossing opening of the relay, provides a reference signal for the current zero-crossing closing, without the need to sample the current signal.

[0047] 2) The waveform sampled by the arc identification module is decomposed multiple times, and the characteristic parameters of the arc are extracted from it. The lead amount is calculated based on the characteristic parameters. After setting a reasonable characteristic parameter threshold, the calculation of the lead amount requires almost no iteration, and zero-crossing switching can be achieved quickly, further extending the service life of the relay.

[0048] 3) The circuit is small in size, low in cost, low in heat generation, and can realize zero-crossing switching on and off of the relay when the load is of any type.

[0049] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 It is a flow chart of a relay zero-crossing switch control method provided by an embodiment of the present invention;

[0051] Figure 2 It is a schematic diagram of the principle of signal filtering and decomposition provided by an embodiment of the present invention;

[0052] Figure 3 It is a schematic diagram of the principle of multiple signal filtering and decomposition provided by an embodiment of the present invention;

[0053] Figure 4 is a structural schematic diagram of a decomposition result provided by an embodiment of the present invention;

[0054] Figure 5 It is an example of a relay zero-crossing switch control method provided by an embodiment of the present invention;

[0055] Figure 6 It is a structural schematic diagram of a relay zero-crossing switch control device provided by an embodiment of the present invention;

[0056] Figure 7 It is a structural block diagram of a relay zero-crossing switch control circuit provided by an embodiment of the present invention;

[0057] Figure 8 It is a structural schematic diagram of a relay zero-crossing switch control circuit provided by an embodiment of the present invention;

[0058] Fig. 9 It is a waveform diagram of a contact voltage drop when a relay is disconnected provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0059] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0060] In order to facilitate the understanding of the embodiments by those skilled in the art, some terms are explained:

[0061] (1) MCU: Microcontroller Unit.

[0062] (2) ADC: Analog-to-Digital Converter, refers to analog-to-digital converter or analog-to-digital converter.

[0063] (3)GPIO: General-purpose input / output, short for general-purpose input / output.

[0064] like Figure 1 As shown, an embodiment of the present invention provides a relay zero-crossing switch control method, comprising:

[0065] Step S1: sampling the output voltage of the arc identification module to obtain N initial sampling data; wherein N is a positive integer;

[0066] Specifically, firstly, the relay is turned on based on the voltage crossing zero, including:

[0067] Get half period T hf ;

[0068] Calculate the second advance amount of the relay based on the voltage zero crossing opening; based on the half cycle T hf and a second lead amount, adjusting the drive signal of the coil of the relay to obtain an actual drive signal; and turning on the relay based on the actual drive signal.

[0069] Among them, the half period T hf is the time difference between a rising edge and a falling edge adjacent to the sampling voltage zero-crossing signal;

[0070] The sampled voltage is obtained based on a voltage detection module.

[0071] In actual application scenarios, after the system is initialized, the MCU first calculates the half-cycle T according to the signal sampled by the voltage detection module. hf , and then wait for the relay on / off command; when the relay's on signal arrives, the relay coil is driven, and the contacts will be closed after a certain delay, so the on signal requires an advance amount to achieve voltage zero crossing to turn on; the MCU calculates the advance amount before the relay is closed to offset the delay from the relay coil to the contacts, and achieve voltage zero crossing to turn on the relay.

[0072] First, record the moment T1 when the coil drive signal is on, and then record the moment T2 when the ADC value of the second pin of the MCU becomes 0. 2 , then T 2 -T 1 is the delay from the coil to the contact end, so that the drive signal leads by T hf -(T 2 -T 1 ) to obtain the actual driving signal, the voltage zero-crossing point can be turned on.

[0073] Then, choose a time t 1 Turn off the relay and sample the output voltage of the arc recognition module through ADC. hf / N time intervals to record data, record N data (that is, data within one signal cycle), denoted as x(n), n = 0, 1, ... N, and then obtain N initial sampling data.

[0074] The embodiment of the present invention is based on the voltage zero-crossing to open the relay and provide a reference signal for the current zero-crossing to shut down, without the need to sample the current signal.

[0075] Step S2: performing multiple decomposition processes on the N initial sampling data to obtain decomposition results;

[0076] Specifically, performing multiple decomposition processes on the N initial sampling data to obtain decomposition results includes:

[0077] Get the j-1th sampling data; where j is a positive integer;

[0078] Perform filtering processing on the j-1th sampling data based on a low-pass filter to obtain a jth low-pass filtering result; at the same time, perform filtering processing on the j-1th sampling data based on a high-pass filter to obtain a jth high-pass filtering result;

[0079] Down-sampling the j-th low-pass filtering result to obtain the j-th sampling data; at the same time, down-sampling the j-th high-pass filtering result to obtain the j-th high-pass down-sampling result;

[0080] Based on the first j high-pass downsampling results and the j-th sampling data, a decomposition result is obtained.

[0081] The decomposition result is calculated based on the following formula:

[0082] x(n)=a j +d j +……+d 1

[0083] Among them, a j is the target low-frequency component; d j is the j-th high-pass downsampling result, 0<n≤N.

[0084] like Figure 2 As shown, in an actual application scenario, two filters are constructed, wherein the two filters are a low-pass filter Lo and a high-pass filter Hi, and the lengths of Lo and Hi are both M, wherein M is a positive integer.

[0085] The N initial sampling data x(n) obtained above are input into two filters at the same time, and then x(n) is filtered based on the low-pass filter based on the convolution operation to obtain F, and F is downsampled at intervals to obtain cA 1 ; At the same time, based on the high-pass filter and convolution operation, x(n) is filtered to obtain G, and G is downsampled at intervals to obtain cD 1 ;

[0086] Among them, the length of F and G is k, k = 0, 1, ... M + N-1;

[0087]

[0088]

[0089] Interval downsampling, specifically extracting points with even subscripts, has

[0090] cA 1 =F(2r),r=0,1,...floor((M+N-1) / 2);

[0091] cD 1 =G(2r),r=0,1,...floor((M+N-1) / 2);

[0092] Among them, floor() means rounding.

[0093] like Figure 3 As shown, for cA 1 Filter again to get cA 2 and cD 2 , and so on, perform multiple signal decompositions to obtain cA j and cD j .

[0094] Step S3: obtaining a corrected current shut-off time based on the decomposition result;

[0095] Specifically, obtaining the corrected current shut-off time based on the decomposition result includes:

[0096] Based on the first high-pass filtering result, the correction amount Δt of the first leading amount is calculated and obtained. 1 ;

[0097] The correction amount Δt based on the first advance amount 1 , obtain the corrected current cut-off time t;

[0098] Where t = t 1 -Δt 1 ;t 1 It is the preset current shut-off time.

[0099] Wherein, the correction amount Δt of the first leading amount 1 Calculated by the following formula:

[0100]

[0101] Among them, T hf is a half period; floor() represents rounding; floor((M+N-1) / 2) is the length of the data of the first high-pass filtering result; i is the subscript with the highest amplitude of the first high-pass filtering result; M is the length of the high-pass filter and the low-pass filter.

[0102] Step S4: verifying the corrected current shut-off time and obtaining a verification result;

[0103] Specifically, verifying the corrected current shut-off time and obtaining the verification result includes:

[0104] Acquire k data points of the target low-frequency component and k down-sampled data of the initial sampled data; wherein k is a positive integer;

[0105] Acquire arc characteristic parameters based on the k data points of the target low-frequency component and the k down-sampled data of the initial sampling data;

[0106] Based on the arc characteristic parameters, the correction current cut-off moment is verified to obtain the verification result.

[0107] The arc characteristic parameters are calculated by the following formula:

[0108]

[0109] Among them, a j(k) is the k data points of the target low-frequency component; x(k) is the k downsampled data of the initial sampling data.

[0110] Step S5: Determine the actual current shutoff time based on the verification result.

[0111] In an embodiment of the present invention, the waveform sampled by the arc identification module is decomposed multiple times, and characteristic parameters of the arc are extracted therefrom. The lead amount is calculated based on the characteristic parameters. After a reasonable characteristic parameter threshold is set, the calculation of the lead amount requires almost no iteration, and zero-crossing switching can be achieved quickly, further extending the service life of the relay.

[0112] like Figure 4 As shown, the above embodiments of the present invention can be implemented by the following implementation methods:

[0113] (1) Calculate the half cycle;

[0114] (2) Turn on the relay and calculate the zero-crossing lead amount;

[0115] (3) Turn off the relay, perform ADC sampling, and obtain the sampling result;

[0116] (4) digitally filtering the sampling results to obtain filtering results;

[0117] (5) downsampling the filtering result;

[0118] (6) Determine whether the number of filtering times reaches a preset number of filtering times. If it does not reach the preset number of filtering times, loop through steps (4), (5), and (6);

[0119] (7) If the number of filtering times reaches the preset number of filtering times, the shutdown advance amount is calculated;

[0120] (8) Calculate arc characteristic parameters;

[0121] (9) Calculate whether the arc characteristic parameters meet the standards; if not, update the lead value, and repeat steps (4), (5), (6), (7), (8), and (9); if the standards are met, obtain the first lead value, thereby achieving accurate current zero-crossing shutdown.

[0122] For example, let j = 3, a set of low-pass filters and high-pass filters with length M = 8 are as follows:

[0123] Lo=[-0.0106, 0.0329, 0.0308, -0.1870, -0.0280, 0.6309, 0.7148, 0.2304]

[0124] Hi=[-0.2304, 0.7148, -0.6309, -0.0280, 0.1870, 0.0308, -0.0329, -0.0106]

[0125] like Figure 5 As shown, 1) using the above high-pass filter and low-pass filter, x(n) can be decomposed into: x(n)=a3+d3+d2+d1 when j=3; where d1 is the component obtained by the first high-pass filtering of x(n), and it can be seen that the data length of d1 is floor((M+N-1) / 2).

[0126] 2) Find the subscript i with the highest amplitude of d1 by sorting, and get the correction value Δt of the lead value 1 ;

[0127]

[0128] The time to turn off the relay is corrected to t = t 1 -Δt 1 .

[0129] 3) Calculate the low-frequency component a obtained by filtering decomposition 3 , and downsample x(n) to make it equal to a 3 The length is consistent.

[0130] 4) Arc characteristic parameters If δ≥δ th (δ th is the factory-set threshold), then the shutdown time t=t 1 -Δt 1 When the current is zero-crossing, the shutdown is realized; if δ≥δ th , then update t 1 Repeat steps 1), 2), 3), and 4) after obtaining the value.

[0131] Among them, δ th The product needs to be calibrated before leaving the factory to avoid multiple calculations failing to reach δ≥δ th situation, improving the efficiency of operations.

[0132] like Figure 6 As shown, an embodiment of the present invention further provides a relay zero-crossing switch control device 600, comprising:

[0133] The sampling module 601 is used to sample the output voltage of the arc identification module to obtain N initial sampling data, wherein N is a positive integer;

[0134] A decomposition module 602 is used to perform multiple decomposition processes on the N initial sampling data to obtain decomposition results;

[0135] An acquisition module 603 is used to acquire a corrected current shut-off time based on the decomposition result;

[0136] A verification module 604 is used to verify the corrected current shut-off moment and obtain a verification result;

[0137] The determination module 605 is used to determine the actual current shut-off time based on the verification result.

[0138] Optionally, performing multiple decomposition processes on the N initial sampling data to obtain decomposition results includes:

[0139] Get the j-1th sampling data; where j is a positive integer;

[0140] Perform filtering processing on the j-1th sampling data based on a low-pass filter to obtain a jth low-pass filtering result; at the same time, perform filtering processing on the j-1th sampling data based on a high-pass filter to obtain a jth high-pass filtering result;

[0141] Down-sampling the j-th low-pass filtering result to obtain the j-th sampling data; at the same time, down-sampling the j-th high-pass filtering result to obtain the j-th high-pass down-sampling result;

[0142] Based on the first j high-pass downsampling results and the j-th sampling data, a decomposition result is obtained.

[0143] Optionally, the decomposition result is calculated based on the following formula:

[0144] x(n)=a j +d j +……+d 1

[0145] Among them, a j is the target low-frequency component; d j is the j-th high-pass downsampling result, 0<n≤N.

[0146] Optionally, acquiring the corrected current shut-off time based on the decomposition result includes:

[0147] Based on the first high-pass filtering result, the correction amount Δt of the first leading amount is calculated and obtained. 1 ;

[0148] The correction amount Δt based on the first advance amount 1 , obtain the corrected current cut-off time t;

[0149] Where t = t 1 -Δt 1 ;t 1 It is the preset current shut-off time.

[0150] Optionally, the correction amount Δt of the first leading amount is 1 Calculated by the following formula:

[0151]

[0152] Among them, T hf is a half period; floor() represents rounding; floor((M+N-1) / 2) is the length of the data of the first high-pass filtering result; i is the subscript with the highest amplitude of the first high-pass filtering result; M is the length of the high-pass filter and the low-pass filter.

[0153] Optionally, verifying the corrected current shut-off moment and obtaining a verification result includes:

[0154] Acquire k data points of the target low-frequency component and k down-sampled data of the initial sampled data; wherein k is a positive integer;

[0155] Acquire arc characteristic parameters based on the k data points of the target low-frequency component and the k down-sampled data of the initial sampling data;

[0156] Based on the arc characteristic parameters, the correction current cut-off moment is verified to obtain the verification result.

[0157] Optionally, the arc characteristic parameter is calculated by the following formula:

[0158]

[0159] Among them, a j (k) is the k data points of the target low-frequency component; x(k) is the k downsampled data of the initial sampling data.

[0160] Optionally, also include,

[0161] Get half period T hf ;

[0162] Calculate a second lead amount for the relay to be turned on based on voltage zero crossing;

[0163] Based on the half period T hf and a second leading amount, adjusting the drive signal of the coil of the relay to obtain an actual drive signal;

[0164] The relay is turned on based on the actual driving signal.

[0165] Optionally, the half period T hf is the time difference between a rising edge and a falling edge adjacent to the sampling voltage zero-crossing signal;

[0166] Wherein, the sampled voltage is obtained based on a voltage detection module.

[0167] The embodiments of the present invention can realize the zero-crossing shutdown of the relay current without using a current sampling circuit. When applied to high current load scenarios, it has the advantages of no additional heat generation, extremely small size, and extremely low cost. At the same time, compared with solutions with similar functions, this solution does not require training or iteration, further improving the life of the relay.

[0168] like Figure 7 As shown, an embodiment of the present invention further provides a relay zero-crossing switch control circuit, comprising:

[0169] Relay;

[0170] an arc identification module, the arc identification module being coupled to a contact end of the relay;

[0171] A processing module is coupled to the arc identification module and the coil control module respectively; the coil control module is coupled to the coil end of the relay.

[0172] Specifically, it also includes a DC power supply; the relay is an electromagnetic relay; the AC power supply is generally 100-240Vac50 / 60Hz; the load can be an active or passive load; the DC power supply is generated by the AC power supply via a switching power supply, and supplies power to the coil control module, the processing module MCU, the voltage zero-crossing detection module, and the arc identification module.

[0173] The embodiments of the present invention have a small circuit size, low cost, low heat generation, and can realize zero-crossing switching on and off of the relay when the load is of any type.

[0174] like Figure 8 As shown, specifically, the coil control module includes: a MOS tube Q1, a third resistor R3 and a fourth resistor R4;

[0175] Wherein, the first end of the third resistor R3 is coupled to the first pin GPIO1 of the processing module MCU; the second end of the third resistor R3 is respectively coupled to the first end of the fourth resistor R4 and the gate of the MOS tube Q1, and the second end of the fourth resistor R4 is grounded; the source of the MOS tube Q1 is grounded; the drain of the MOS tube Q1 is coupled to the first pin of the coil end of the relay, the second pin of the coil end of the relay is respectively coupled to the power supply voltage VCC and the first end of the first capacitor C1, and the second end of the first capacitor C1 is grounded;

[0176] Both sides of the coil end are coupled in parallel with the two ends of the first diode D1, wherein the output end of the first diode D1 is coupled to the second pin of the coil end, the first end of the first capacitor C1 and the power supply voltage VCC respectively, and the input end of the first diode D1 is coupled to the first pin of the coil end and the drain of the MOS tube Q1 respectively.

[0177] The arc identification module includes a first resistor R1, a second resistor R2, an operational amplifier U1, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9 and a tenth resistor R10;

[0178] The first end of the first resistor R1 is coupled to the first pin of the contact end of the relay and the first end of the load respectively; the second pin of the contact end of the relay is coupled to the neutral line and is grounded;

[0179] The second end of the first resistor R1 is coupled to the first end of the eighth resistor R8 and the first end of the second resistor R2 respectively; the second end of the second resistor R2 is grounded;

[0180] The second end of the eighth resistor R8 is coupled to the first end of the seventh resistor R7 and the non-inverting input end of the operational amplifier U1 respectively; the second end of the seventh resistor R7 is coupled to the power supply voltage VCC;

[0181] A first end of the ninth resistor R9 is grounded, a second end of the ninth resistor R9 is respectively coupled to the inverting input end of the operational amplifier U1 and a first end of the tenth resistor R10, and a second end of the tenth resistor R10 is coupled to the output end of the operational amplifier U1;

[0182] The output terminal of the operational amplifier U1 is coupled to the second pin ADC of the MCU.

[0183] The arc identification module is used to detect the voltage waveform at both ends when the contacts are disconnected, and then indirectly identify the state of the arc when the relay is turned off.

[0184] The voltage zero-crossing detection module includes a fifth resistor R5, a sixth resistor R6, a second diode D2 and a second transistor Q2;

[0185] The first end of the sixth resistor R6 is coupled to the live wire and the second end of the load respectively, the second end of the sixth resistor R6 is coupled to the input end of the second diode D2, the output end of the second diode D2 is coupled to the base of the transistor Q2; the emitter of the transistor Q2 is grounded;

[0186] The collector of the transistor Q2 and the first end of the fifth resistor R5 are respectively coupled to the third pin GPIO2 of the MCU;

[0187] The third pin GPIO3 of the MCU is the control input of the external relay, which can be generated by other circuits or manually controlled; when the third pin GPIO3 inputs a high level, the MCU believes that the relay needs to be turned on; when the third pin GPIO3 inputs a low level, the MCU believes that the relay needs to be turned off.

[0188] A second terminal of the fifth resistor R5 is coupled to the power voltage VCC.

[0189] The voltage zero-crossing detection module is used to realize the zero-crossing switching of the relay.

[0190] like Fig. 9 As shown in the figure, it is the waveform of the contact voltage drop when the relay is disconnected. The vertical axis is the contact voltage drop sampled by the ADC, t 1 is the moment when the contacts open, t 2 The moment when the arc is extinguished, t 3 is the zero-crossing point of the contact voltage drop. According to the characteristics of the arc, t 1 -t 2 During this period, the contacts are not effectively disconnected, so the voltage drop across the contacts cannot return to a sine wave. At the same time, the burning of the arc makes the voltage drop across the contacts greater than 0, so t 1 and t 2 The voltage is not equal to 0.

[0191] The embodiment of the present invention analyzes the sampled contact voltage drop to correct the relay shut-off moment and evaluate the severity of the arc.

[0192] The embodiments of the present invention can be implemented based on the following working principles:

[0193] 1) After the circuit is connected to the power supply, when the live line is in the positive half cycle relative to the neutral line, the current flows from the live line into the sixth resistor R6, the second diode D2, the BE pole of the transistor Q2 (wherein the base of the transistor can be represented by B, the emitter can be represented by E, and the collector can be represented by C) and the reference ground in sequence, and the transistor Q2 is turned on. After the transistor Q2 is turned on, the current flows from the power supply voltage VCC into the fifth resistor R5 and the CE pole of the transistor Q2. At this time, the collector of the transistor Q2 outputs a low level; when the live line is in the negative half cycle relative to the neutral line, no current flows into the sixth resistor R6 and the second diode D2, and the transistor Q2 is not turned on. At this time, the collector of the transistor Q2 outputs a high level, so the collector of the transistor Q2 outputs a square wave, and its edge corresponds to the zero-crossing point of the AC input voltage.

[0194] 2) When the relay needs to be turned on, the MCU calculates the turn-on time according to the edge of the collector output waveform of the transistor Q2, and makes the first pin GPIO1 output a high level to the third resistor R3, so that the resistance of the fourth resistor R4 is much larger than the third resistor R3, then the gate of the MOS tube Q1 is at a high level, the MOS tube Q1 is turned on, and the current flows from the power supply voltage VCC to the relay coil, the MOS tube Q1 and the reference ground in sequence. After the current flows through the relay coil, the electromagnetic field generated acts on the armature and causes the contacts to close. After the contacts are closed, the load is connected to the power supply.

[0195] 3) When the relay needs to be turned off, the MCU needs to sample the analog signal from the output of the operational amplifier U1, digitize it and calculate the turn-off time. After the calculation is completed, the first pin GPIO1 outputs a low level to the third resistor R3, then the gate of the MOS tube Q1 is low level, the MOS tube Q1 is turned off, and the energy stored in the relay coil is discharged through the first diode D1. After the relay coil energy is discharged to the turn-off threshold, the electromagnetic field cannot maintain the contact attraction, the contact is disconnected, and the load power supply is cut off. The operational amplifier U1, the seventh resistor R7, the eighth resistor R8, the ninth resistor R9 and the tenth resistor R10 form a bias amplifier circuit. The contact voltage is divided by the first resistor R1 and the second resistor R2 and then transmitted to the in-phase input terminal of the operational amplifier U1, and is biased and amplified and output to the second pin ADC of the MCU.

[0196] In addition, other structures and functions of the circuits in the embodiments of the present invention are known to those skilled in the art and are not described herein in detail to reduce redundancy.

[0197] It should be noted that the logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be specifically implemented in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in combination with these instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in combination with these instruction execution systems, devices or apparatuses. More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection portion with one or more wirings (electronic device), a portable computer disk box (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium and then editing, interpreting or processing in other suitable ways if necessary, and then stored in a computer memory.

[0198] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0199] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0200] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0201] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0202] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0203] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0204] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A relay zero-crossing switch control method, characterized in that: include: Sampling the output voltage of the arc identification module to obtain N initial sampling data, wherein N is a positive integer; Perform multiple decomposition processes on the N initial sampling data to obtain decomposition results; Acquire a corrected current shut-off time based on the decomposition result; Verifying the correction current shut-off moment and obtaining a verification result; Based on the verification result, determining the actual current shut-off time; The performing multiple decomposition processes on the N initial sampling data to obtain decomposition results includes: Get the j-1th sampling data; where j is a positive integer; Perform filtering processing on the j-1th sampling data based on a low-pass filter to obtain a jth low-pass filtering result; at the same time, perform filtering processing on the j-1th sampling data based on a high-pass filter to obtain a jth high-pass filtering result; Down-sampling the j-th low-pass filtering result to obtain the j-th sampling data; at the same time, down-sampling the j-th high-pass filtering result to obtain the j-th high-pass down-sampling result; Based on the first j high-pass downsampling results and the j-th sampling data, obtaining a decomposition result; The obtaining of the corrected current shut-off time based on the decomposition result includes: Based on the first high-pass filtering result, the correction amount of the first leading amount is calculated and obtained. ; The correction amount based on the first advance amount , obtain the corrected current cut-off time t; Where, t = ; is the preset current shut-off moment; Verifying the correction current shut-off time and obtaining the verification result includes: Acquire k data points of the target low-frequency component and k down-sampled data of the initial sampled data; wherein k is a positive integer; Acquire arc characteristic parameters based on the k data points of the target low-frequency component and the k down-sampled data of the initial sampling data; Based on the arc characteristic parameters, the correction current cut-off moment is verified to obtain the verification result.

2. The method according to claim 1, characterized in that: The decomposition result is calculated based on the following formula: in, is the target low-frequency component; is the j-th high-pass downsampling result, 0<n≤N.

3. The method according to claim 1, characterized in that: The correction amount of the first leading amount Calculated by the following formula: in, is a half period; floor() means rounding; is the length of the data of the first high-pass filtering result; i is the subscript with the highest amplitude of the first high-pass filtering result; M is the length of the high-pass filter and the low-pass filter.

4. The method according to claim 1, characterized in that: The arc characteristic parameters are calculated by the following formula: in, are k data points of the target low-frequency component; are the k downsampled data of the initial sampled data.

5. The method according to any one of claims 1 to 4, characterized in that: Also includes, Get half period ; Calculate a second lead amount for the relay to be turned on based on voltage zero crossing; Based on the half cycle and a second lead amount, adjusting the drive signal of the coil of the relay to obtain an actual drive signal; The relay is turned on based on the actual driving signal.

6. The method according to claim 5, characterized in that The half cycle is the time difference between a rising edge and a falling edge adjacent to the sampling voltage zero-crossing signal; Wherein, the sampled voltage is obtained based on a voltage detection module.

7. A relay zero-crossing switch control circuit, characterized in that: include: Relay; an arc identification module, the arc identification module being coupled to a contact end of the relay; A voltage zero-crossing detection module, the voltage zero-crossing detection module is coupled to the arc identification module and the load of the relay zero-crossing switch control circuit respectively, and the voltage zero-crossing detection module is used to open the relay when detecting that the voltage waveform passes through the zero point; A processing module, wherein the processing module is coupled to the arc identification module, the voltage zero-crossing detection module and the coil control module respectively; the coil control module is coupled to the coil end of the relay, and the processing module is used to execute the method described in any one of claims 1-6 to control the relay.

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