Voltage isolation sampling circuit, zero cross detection circuit, circuit board and electrical equipment

Abstract

The invention discloses a voltage isolation sampling circuit, a zero cross detection circuit, a circuit board and electrical equipment, and the circuit comprises an AC voltage input unit, a sampling unit, a voltage reference unit and an amplification unit. The first capacitor is arranged between the first alternating-current input end and the sampling device to realize isolation between a sampling signal of an upper half period and alternating-current voltage, and the second capacitor is arranged between the second alternating-current input end and the sampling device to realize isolation between a sampling signal of a lower half period and alternating-current voltage; according to the voltage isolation sampling circuit and the sampling unit, compared with a mode of adopting an optocoupler device or a transformer device to realize isolation sampling, loss required by signal conversion does not need to be provided, large capacitive reactance can be provided by selecting small capacitors as the first capacitor and the second capacitor, power loss of alternating current voltage isolation sampling can be effectively reduced, and the voltage isolation sampling efficiency is improved. And low-power-consumption sampling is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of sampling circuits, and in particular to a voltage isolation sampling circuit, a zero-crossing detection circuit, a circuit board and electrical equipment. Background Art

[0002] At present, high-voltage voltage sampling and zero-crossing signal sampling play an important role in power electronic systems. The existing technology generally uses a voltage divider resistor plus an optical coupler to realize high-voltage side signal transmission to achieve high-voltage voltage and zero-crossing signal sampling;

[0003] However, sampling by using a sampling voltage divider resistor plus an optocoupler to transmit the high-voltage side signal will result in a large loss. Specifically, in order to achieve signal transmission, the optocoupler needs to reach a current of more than 1mA. Since the input voltage is a sinusoidal signal, it is necessary to consider that the optocoupler can also be turned on at low voltage, resulting in a circuit loss of at least 0.3W. This makes the existing high-voltage voltage and zero-crossing signal sampling specific implementation scheme have the problem of high power consumption during sampling. Summary of the invention

[0004] The purpose of the present invention is to solve at least one of the technical problems existing in the prior art, and to provide a voltage isolation sampling circuit, a zero-crossing detection circuit, a circuit board and an electrical device, which can effectively reduce the power loss during the voltage signal sampling and zero-crossing signal sampling of the AC voltage input signal, and realize low-power sampling of high voltage and zero-crossing signals.

[0005] In a first aspect, an embodiment of the present invention provides a voltage isolation sampling circuit, comprising:

[0006] An AC voltage input unit, comprising a first AC input terminal and a second AC input terminal;

[0007] A sampling unit, comprising a first capacitor, a sampling device and a second capacitor, wherein the first AC input terminal, the first capacitor, the sampling device, the second capacitor and the second AC input terminal are connected in sequence, and two ends of the sampling device are used to output a sampling signal;

[0008] A voltage reference unit, used for providing a DC reference voltage;

[0009] The amplifier unit, the output end of the voltage reference unit and the two ends of the sampling device are connected to the input end of the amplifier unit, and the amplifier unit is used to raise the sampling signal to the DC reference voltage to output a voltage sampling signal.

[0010] The voltage isolation sampling circuit provided by the embodiment of the present invention has at least the following beneficial effects: by setting a sampling unit to sample the AC voltage input from the AC voltage input unit, a first capacitor is set between the first AC input terminal and the sampling device to achieve isolation between the sampling signal and the AC voltage in the first half cycle, and a second capacitor is set between the second AC input terminal and the sampling device to achieve isolation between the sampling signal and the AC voltage in the second half cycle; an amplification unit is set to raise the sampling signal to the DC reference voltage, so that the sampling signal changes near the DC reference voltage, so that the voltage sampling signal outputted finally can be identified. Compared with the method of using an optocoupler device or a transformer device to achieve isolated sampling, the sampling unit of the voltage isolation sampling circuit does not need to provide the loss required for signal conversion, and the first capacitor and the second capacitor can provide a large capacitive reactance by using small capacitors, which can effectively reduce the power loss of AC voltage isolation sampling and achieve low-power sampling.

[0011] In some embodiments, the sampling device includes a first resistor connected between the first capacitor and the second capacitor.

[0012] In some embodiments, the amplification unit includes a first operational amplifier, the two ends of the sampling device are respectively connected to the non-inverting terminal and the inverting terminal of the first operational amplifier, and the output end of the voltage reference unit is connected to the non-inverting terminal of the first operational amplifier.

[0013] In some embodiments, the amplification unit also includes a second resistor, a third resistor, a fourth resistor and a fifth resistor, one end of the sampling device is connected to one end of the second resistor, the output end of the voltage reference unit is connected to one end of the third resistor, the other ends of the second resistor and the third resistor are connected to the in-phase terminal of the first op amp; the other end of the sampling device is connected to one end of the fourth resistor, the other end of the fourth resistor is connected to the inverting terminal of the first op amp and is connected to the output terminal of the first op amp through the fifth resistor.

[0014] In some embodiments, the voltage reference unit includes a three-terminal controllable voltage regulator and a sixth resistor, one end of the sixth resistor is connected to a DC power supply terminal, the other end of the sixth resistor is connected to a negative electrode and a reference electrode of the three-terminal controllable voltage regulator, the positive electrode of the three-terminal controllable voltage regulator is grounded, and the reference electrode of the three-terminal controllable voltage regulator serves as the output end of the voltage reference unit.

[0015] In some embodiments, the voltage isolation sampling circuit also includes a seventh resistor and an eighth resistor, the output end of the first op amp is connected to one end of the seventh resistor, the other end of the seventh resistor is connected to one end of the eighth resistor and is used to output the voltage sampling signal, and the other end of the eighth resistor is grounded.

[0016] In a second aspect, an embodiment of the present invention provides a zero-crossing detection circuit, comprising a comparison unit and the voltage isolation sampling circuit described in any embodiment of the first aspect of the present application, wherein the output end of the amplification unit is connected to the input end of the comparison unit, and the comparison unit is used to output a comparison signal with a zero-crossing signal.

[0017] The zero-crossing detection circuit provided according to the embodiment of the present invention has at least the following beneficial effects: by setting a comparison unit, the voltage sampling signal output by the voltage isolation sampling circuit is compared with the reference signal, thereby outputting a comparison signal with a high level for half a cycle and a low level for half a cycle, and the comparison signal can carry the zero-crossing signal of the AC voltage input from the AC voltage input unit.

[0018] In some embodiments, the comparison unit includes a second operational amplifier and a ninth resistor, the output of the amplification unit is connected to the non-inverting terminal of the second operational amplifier, the output of the voltage reference unit is connected to the inverting terminal of the second operational amplifier, the output of the second operational amplifier is connected to one end of the ninth resistor, and the other end of the ninth resistor is grounded.

[0019] In some embodiments, the zero-crossing detection circuit further includes a phase shift unit disposed between the amplifying unit and the comparing unit, and the phase shift unit is used to perform a 90° phase shift on the output signal of the amplifying unit.

[0020] In some embodiments, the phase shift unit includes a third capacitor, a tenth resistor, an eleventh resistor, a twelfth resistor and a third operational amplifier, the output end of the comparison unit is connected to one end of the third capacitor, the other end of the third capacitor is connected to one end of the tenth resistor and the in-phase end of the third operational amplifier, the inverting end of the third operational amplifier is connected to one end of the eleventh resistor and one end of the twelfth resistor, the other end of the eleventh resistor is grounded, and one end of the twelfth resistor is connected to the output end of the third operational amplifier.

[0021] In some embodiments, the comparison unit includes a second operational amplifier and a ninth resistor, the output end of the phase shift unit is connected to the non-inverting end of the second operational amplifier, the inverting end of the second operational amplifier is grounded, the output end of the second operational amplifier is connected to one end of the ninth resistor, and the other end of the ninth resistor is grounded.

[0022] In some embodiments, the phase shift unit further includes a thirteenth resistor, and the output end of the third operational amplifier is grounded through the thirteenth resistor.

[0023] In a third aspect, an embodiment of the present invention provides a method for obtaining a zero-crossing signal, which is applied to a zero-crossing detection circuit in which a phase shifting unit is not provided in the embodiment of the second aspect above, and the method for obtaining a zero-crossing signal includes:

[0024] Determine a signal period according to a time interval between two adjacent rising edges or a time interval between two adjacent falling edges in the comparison signal;

[0025] The rising edge signal and the falling edge signal in the comparison signal are respectively delayed by one quarter of the signal period to obtain a zero-crossing signal.

[0026] The zero-crossing signal acquisition method provided in the embodiment of the present invention has at least the following beneficial effects: since the sampling unit is provided with the first capacitor and the second capacitor, there is a 90-degree phase shift between the voltage sampling signal output by the amplification unit and the comparison signal output by the comparison unit and the AC voltage input from the AC voltage input unit. Therefore, the signal period is first determined from the comparison signal, and then the rising edge signal and the falling edge signal in the comparison signal are delayed by one quarter of the signal period, so that an accurate zero-crossing signal can be obtained.

[0027] In a fourth aspect, an embodiment of the present invention provides a circuit board, comprising the voltage isolation sampling circuit described in any embodiment of the first aspect of the present application or the zero-crossing detection circuit described in any embodiment of the second aspect of the present application.

[0028] In a fifth aspect, an embodiment of the present invention provides an electrical device, comprising the circuit board described in any embodiment of the third aspect of the present application.

[0029] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings are used to provide a further understanding of the technical solution of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the technical solution of the present invention and do not constitute a limitation to the technical solution of the present invention.

[0031] The present invention is further described below in conjunction with the accompanying drawings and embodiments;

[0032] Figure 1 is a circuit diagram of a voltage isolation sampling circuit provided by an embodiment of the present invention;

[0033] Figure 2 is another circuit schematic diagram of a voltage isolation sampling circuit provided by another embodiment of the present invention;

[0034] Figure 3 is a working waveform diagram of a voltage isolation sampling circuit provided by another embodiment of the present invention;

[0035] Figure 4 is a circuit diagram of a zero-crossing detection circuit provided by another embodiment of the present invention;

[0036] Figure 5 is a working waveform diagram of a zero-crossing detection circuit provided by another embodiment of the present invention;

[0037] Figure 6 is a circuit diagram of a zero-crossing detection circuit with a phase shift unit provided by another embodiment of the present invention;

[0038] Figure 7 is another circuit schematic diagram of a zero-crossing detection circuit with a phase shift unit provided by another embodiment of the present invention;

[0039] Figure 8 is another working waveform diagram of a zero-crossing detection circuit provided by another embodiment of the present invention;

[0040] Fig. 9 It is a flowchart of a method for obtaining a zero-crossing signal provided by another embodiment of the present invention.

[0041] Reference numerals:

[0042] 110, AC voltage input unit; 111, sampling device; 120, sampling unit; 130, voltage reference unit; 140, amplification unit; 210, comparison unit; 220, phase shift unit. DETAILED DESCRIPTION

[0043] This section will describe in detail the specific embodiments of the present invention. The preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present invention, but it cannot be understood as a limitation on the scope of protection of the present invention.

[0044] It should be understood that in the description of the embodiments of the present invention, if there is a description of "first", "second", etc., it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features. "At least one" means one or more, "more than" means more than two, greater than, less than, exceeding, etc. are understood to not include the number itself, above, below, within, etc. are understood to include the number itself, and "several" means one or more, unless otherwise clearly and specifically limited. "And / or" describes the association relationship of associated objects, indicating that three relationships can exist. It can be understood that A and / or B can represent the situation where A exists alone, A and B exist at the same time, or B exists alone. Among them, A and B can be singular or plural.

[0045] In addition, unless otherwise clearly specified and limited, the term "connected / connected" should be understood in a broad sense, for example, it can be a fixed connection or a movable connection, a detachable connection or a non-detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or can communicate with each other; it can be directly connected or indirectly connected through an intermediate medium. It should be noted that although the logical order is shown in the flowchart, in some cases, the steps shown or described can be performed in a different order from that in the flowchart. It should be noted that the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0046] In the prior art, existing isolated voltage signal sampling and zero-crossing signal sampling basically use voltage divider resistors plus optocouplers to realize high-voltage side signal transmission, thereby achieving the purpose of high-voltage voltage and zero-crossing signal sampling; however, since the optocoupler needs to reach a current of more than 1mA to realize signal transmission, the circuit loss of the prior art solution is relatively large.

[0047] To solve the above problems, an embodiment of the present invention provides a voltage isolation sampling circuit, a zero-crossing detection circuit, a zero-crossing signal acquisition method, a circuit board and an electrical device, wherein the voltage isolation sampling circuit includes an AC voltage input unit, a sampling unit, a voltage reference unit and an amplification unit, wherein the AC voltage input unit and the sampling unit are used to receive an input voltage and output a corresponding sampling signal, the voltage reference unit is used to provide a DC reference voltage, and the amplification unit is used to raise the sampling signal to the DC reference voltage to output a voltage sampling signal; the sampling unit is set to sample the AC voltage input from the AC voltage input unit, a first capacitor is set between the first AC input terminal and the sampling device to achieve isolation between the sampling signal and the AC voltage in the upper half cycle, and a second capacitor is set between the second AC input terminal and the sampling device to achieve isolation between the sampling signal and the AC voltage in the lower half cycle; an amplification unit is set to raise the sampling signal to the DC reference voltage, so that the sampling signal changes near the DC reference voltage, so that the voltage sampling signal finally output can be identified. Compared with the method of using optocoupler devices or transformer devices to achieve isolated sampling, the sampling unit of the voltage isolation sampling circuit does not need to provide the loss required for signal conversion, and the first capacitor and the second capacitor can provide a larger capacitive reactance by using small capacitors, which can effectively reduce the power loss of AC voltage isolation sampling and achieve low-power sampling.

[0048] The embodiments of the present invention are further described below in conjunction with the accompanying drawings.

[0049] Reference Figure 1The first aspect of the present invention provides a voltage isolation sampling circuit, including an AC voltage input unit 110, a sampling unit 120, a voltage reference unit 130 and an amplification unit 140, wherein:

[0050] The AC voltage input unit 110 includes a first AC input terminal Q1 and a second AC input terminal Q2;

[0051] The sampling unit 120 includes a first capacitor C1, a sampling device 111, and a second capacitor C2. The first AC input terminal Q1, the first capacitor C1, the sampling device 111, the second capacitor C2, and the second AC input terminal Q2 are connected in sequence. Both ends of the sampling device 111 are used to output a sampling signal.

[0052] The voltage reference unit 130 is used to provide a DC reference voltage;

[0053] The output end of the voltage reference unit 130 and two ends of the sampling device 111 are connected to the input end of the amplification unit 140 . The amplification unit 140 is used to increase the sampling signal to a DC reference voltage to output a voltage sampling signal.

[0054] refer to Figure 1 , Figure 1 is a circuit diagram of a voltage isolation sampling circuit provided by an embodiment of the present invention. In some embodiments, the AC voltage input unit 110 includes a first AC input terminal Q1 and a second AC input terminal Q2, and the voltage between the first AC input terminal Q1 and the second AC input terminal Q2 is the input voltage Vin to be sampled; in a specific embodiment, the sampling device 111 includes a first resistor R1, that is, the sampling unit 120 includes a first capacitor C1, a first resistor R1 and a second capacitor C2. By connecting the first AC input terminal Q1, the first capacitor C1, the first resistor R1, the second capacitor C2 and the second AC input terminal Q2 in sequence, a sampling unit is formed, thereby realizing high voltage isolation sampling of the input voltage Vin, so that the two ends of the first resistor R1 are used to output the sampling signal, and then the sampling signal is used in the subsequent process to output the voltage sampling signal Vout in cooperation with the voltage reference unit and the amplification unit, and effectively reduce the power consumption of high voltage sampling.

[0055] It should be noted that, in addition to being composed of only the first resistor R1 , the sampling device 111 may also include other components, for example, may be composed of a plurality of resistors, or a resistor plus a capacitor, or a resistor plus an inductor.

[0056] In some embodiments, the DC reference voltage provided by the voltage reference unit is used to raise the sampling signal so that the sampling signal changes near the reference voltage. When the amplification unit superimposes the sampling signal on the DC reference voltage and amplifies it, it outputs a voltage sampling signal, thereby solving the problem in the prior art that the control chip cannot recognize smaller sampling signals.

[0057] In some embodiments, after the input voltage signal is obtained and processed by the amplifier circuit and the Vout signal with the reference voltage raised is outputted, the input voltage value can be calculated by calculating the capacitive reactance values ​​of the first capacitor C1 and the second capacitor C2. Then, the capacitive reactance values ​​of the first capacitor C1 and the second capacitor C2 are determined according to the input voltage frequency value f, and the input voltage Uin is obtained according to the amplification factor X of the amplifier unit.

[0058] Specifically, the calculation process of the capacitive reactance value Z1 of the first capacitor C1 and the capacitive reactance value Z2 of the second capacitor C2 is:

[0059] Z1=1 / (2πfC1); Z2=1 / (2πfC2); (f is the input voltage frequency value)

[0060] Then the voltage on the first resistor R1 is U1=R1*Uin / (R1+Z1+Z2); (Uin is the input voltage value)

[0061] The amplification factor of the discharge circuit is X, then: (Vout-rms is the effective value of the output signal Vout after removing the lift voltage 2.5)

[0062]

[0063] Through the above calculation process, the input voltage value can be effectively calculated according to the signal Vout after voltage sampling and amplification.

[0064] In some embodiments, the resistance value of the first resistor R1 in the present application can be set according to common means of those skilled in the art, and the specific resistance value of the first resistor R1 does not constitute a limitation to the present application.

[0065] refer to Figure 2 , Figure 2is another circuit schematic diagram of a voltage isolation sampling circuit provided by another embodiment of the present invention. In some embodiments, the amplification unit includes a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5 and a first operational amplifier A1. One end of the first resistor R1 is connected to one end of the second resistor R2, the output end of the voltage reference unit 130 is connected to one end of the third resistor R3, and the other ends of the second resistor R2 and the third resistor R3 are connected to the in-phase end of the first operational amplifier A1; the other end of the first resistor R1 is connected to one end of the fourth resistor R4, and the other end of the fourth resistor R4 is connected to the inverting end of the first operational amplifier A1 and is connected to the output end of the first operational amplifier A1 through the fifth resistor R5.

[0066] refer to Figure 2 The second resistor R2, the third resistor R3, the fourth resistor R4, the fifth resistor R6 and the first operational amplifier A1 work together to receive the sampling signal of the sampling unit 120 and the DC reference voltage of the voltage reference unit 130. The sampling signal of the sampling unit 120 is input into the in-phase terminal and the reverse terminal of the first operational amplifier A1 through the two ends of the first resistor R1. One end of the first resistor R1 is connected to the reverse terminal of the first operational amplifier A1 through the fourth resistor R4, and is connected to the output terminal of the first operational amplifier A1 through the fourth resistor R4 and the fifth resistor R5. The other end of the sampling device R1 is connected to the in-phase terminal of the first operational amplifier A1 through the second resistor R2, so that the first operational amplifier A1 receives the sampling signal. At the same time, the DC reference voltage of the voltage reference unit is connected to the in-phase terminal of the first operational amplifier A1 through the third resistor R3, so that the first operational amplifier A1 receives the DC reference voltage, and then the sampling signal is superimposed on the DC reference voltage and amplified, and the voltage sampling signal is output at the output terminal.

[0067] In some embodiments, the third resistor R3 is the output resistor of the DC reference voltage of the voltage reference unit 130, the second resistor R2 and the fourth resistor R4 are respectively the output resistors of the sampling signals output from both ends of the sampling device, and play the role of limiting current to protect the operational amplifier. The reverse end of the first operational amplifier A1 is connected to the output end of the first operational amplifier A1 through the fifth resistor R5, so that the first operational amplifier A1 can amplify the sampling signal, and when the DC reference voltage of the voltage reference unit 130 is input to the same direction end of the first operational amplifier A1, the sampling signal is superimposed on the DC reference voltage, thereby realizing low-power AC voltage input signal voltage signal sampling in the subsequent processing process, effectively reducing the power consumption of high-voltage voltage sampling.

[0068] In some embodiments, the voltage reference unit 130 includes a three-terminal controllable voltage regulator D1 and a sixth resistor R6, one end of the sixth resistor R6 is connected to the DC power supply terminal Q3, the other end of the sixth resistor R6 is connected to the negative electrode and the reference electrode of the three-terminal controllable voltage regulator D1, the positive electrode of the three-terminal controllable voltage regulator D1 is grounded, and the reference electrode of the three-terminal controllable voltage regulator D1 serves as the output end of the voltage reference unit 130.

[0069] refer to Figure 2 The three-terminal controllable voltage regulator D1, the sixth resistor R6 and the DC power supply end work together to provide a DC reference voltage for raising the sampling signal, wherein the voltage between the first terminal Q3 and the second terminal Q4 of the DC power supply end is the voltage of the DC power supply end. In some embodiments, the present application uses a DC circuit source with a DC voltage of 5V to access the circuit of the amplifying unit to provide DC power for the amplifying unit. The first terminal Q3 of the DC power supply end is connected to the negative electrode and the reference electrode of the three-terminal controllable voltage regulator D1 through the sixth resistor R6, and the positive electrode of the three-terminal controllable voltage regulator D1 is connected to the second terminal Q4 of the DC power supply end and grounded, so that the reference electrode of the three-terminal controllable voltage regulator D1 is used as the output terminal of the voltage reference unit, and the DC reference voltage Vref is output, which is used to raise the sampling signal so that the amplifying unit can obtain the output voltage to achieve isolated sampling.

[0070] refer to Figure 2 In some embodiments, the voltage isolation sampling circuit further includes a seventh resistor R7 and an eighth resistor R8, the output end of the first operational amplifier A1 is connected to one end of the seventh resistor R7, the other end of the seventh resistor R7 is connected to one end of the eighth resistor R8 and is used to output a voltage sampling signal, and the other end of the eighth resistor R8 is grounded, wherein the seventh resistor R7 is used as the output voltage of the voltage sampling signal output by the first operational amplifier A1, and cooperates with the grounded eighth resistor R8 to play a role of voltage division and voltage stabilization, so that the output voltage sampling signal Vout is more stable.

[0071] In some embodiments, the ratio of the resistance values ​​of the seventh resistor R7 and the ninth resistor R9 determines the amplification factor of the amplifier unit. Therefore, those skilled in the art can adjust the resistance values ​​of the seventh resistor R7 and the ninth resistor R9 according to the actual use process or application environment so that the present application can effectively amplify the input voltage signal, so that the present application scheme can effectively realize the voltage signal sampling of the low-power AC voltage input signal.

[0072] refer to Figure 3 , Figure 3 : is a working waveform diagram of a voltage isolation sampling circuit provided by another embodiment of the present invention, wherein Vin is the input voltage corresponding to the sampling signal, and Vout is the voltage sampling signal obtained after being superimposed on the DC reference voltage and amplified by the amplification unit. It can be seen that the voltage sampling signal is raised by a DC reference voltage relative to the sampling signal. For example, Figure 3In the figure, the center point of the sampling signal fluctuation (the vertical coordinate of the zero point) is 0, and the center point of the voltage sampling signal fluctuation is 2.5, that is, the voltage sampling signal is raised by 2.5V relative to the sampling signal.

[0073] In some embodiments, reference Figure 4 , Figure 4 It is a circuit schematic diagram of a zero-crossing detection circuit provided by another embodiment of the present invention. The second aspect embodiment of the present invention provides a zero-crossing detection circuit, including a comparison unit 210 and a voltage isolation sampling circuit of any embodiment of the first aspect of the present application. The output end of the amplification unit 140 is connected to the input end of the comparison unit 210, and the comparison unit 210 is used to output a comparison signal with a zero-crossing signal. Since the voltage isolation sampling circuit of any embodiment of the first aspect of the present application can effectively perform isolation voltage sampling to obtain a voltage sampling signal, the comparison unit 210 in the zero-crossing detection circuit can perform waveform conversion processing on the voltage sampling signal to obtain a comparison signal with a zero-crossing signal.

[0074] In this embodiment, by setting a comparison unit 210, the voltage sampling signal output by the voltage isolation sampling circuit is compared with the reference signal, thereby outputting a comparison signal with a high level for half a cycle and a low level for half a cycle, and the comparison signal can carry the zero-crossing signal of the AC voltage input from the AC voltage input unit.

[0075] In some embodiments, zero-crossing detection is a detection made by the system in an AC system when the waveform switches from the positive half-cycle to the negative half-cycle and passes through the zero position. It can be used as a switching circuit or frequency detection. The existing zero-crossing detection generally has the problem of high power consumption, and the present application can effectively reduce the sampling power consumption of high voltage and zero-crossing signals, so that the zero-crossing detection circuit in the present application can realize zero-crossing signal sampling and voltage signal sampling of AC voltage input signals with ultra-low power consumption (below 1mW).

[0076] In some embodiments, the comparison unit includes a signal comparison circuit. After the input voltage signal is isolated by the input voltage signal isolation processing circuit, it is input into the amplifier circuit for processing. After the amplifier circuit combines with the voltage reference circuit to raise the zero point of the input voltage signal to the reference voltage, the comparison circuit performs a waveform conversion on the input voltage signal and outputs a zero-crossing sampling signal Vcross carrying a zero-crossing signal.

[0077] refer to Figure 4In some embodiments, the comparison unit includes a second operational amplifier A2 and a ninth resistor R9, the output end of the amplification unit 140 is connected to the in-phase end of the second operational amplifier A2, the output end of the voltage reference unit 130 is connected to the inverting end of the second operational amplifier A2, the output end of the second operational amplifier A2 is connected to one end of the ninth resistor R9, and the other end of the ninth resistor R9 is grounded, wherein the in-phase end of the second operational amplifier A2 is used to receive the voltage sampling signal from the amplification unit 140 in the voltage isolation sampling circuit, and the inverting end of the second operational amplifier A2 is used to receive the DC reference voltage from the voltage reference unit 130 in the voltage isolation sampling circuit. The second operational amplifier A2 compares and processes the voltage sampling signal with the DC reference voltage, and outputs a zero-crossing sampling signal Vcross, thereby realizing low-power zero-crossing signal sampling of the AC voltage input signal, and effectively reducing the sampling power consumption of the high voltage and the zero-crossing signal.

[0078] In some embodiments, Figure 4 The AC voltage input unit 110 includes a first AC input terminal Q1 and a second AC input terminal Q2, and the voltage between the first AC input terminal Q1 and the second AC input terminal Q2 is the input voltage Vin to be sampled; the sampling unit 120 includes a first capacitor C1, a first resistor R1, and a second capacitor C2, and the first AC input terminal Q1, the first capacitor C1, the first resistor R1, the second capacitor C2, and the second AC input terminal Q2 are connected in sequence; the amplification unit 140 includes a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R6 and a first operational amplifier A1, and the two ends of the first resistor R1 are input to the in-phase terminal and the reverse terminal of the first operational amplifier A1, and one end of the first resistor R1 is connected to the reverse terminal of the first operational amplifier A1 through the fourth resistor R4; the voltage reference unit 130 includes a three-terminal controllable voltage regulator D1, a sixth resistor R6 and a DC power supply terminal, which are used to provide a DC reference voltage for raising the sampling signal, wherein the voltage between the first terminal Q3 and the second terminal Q4 of the DC power supply terminal is the voltage of the DC power supply terminal.

[0079] In some embodiments, reference Figure 5 , Figure 5 : is a working waveform diagram of a zero-crossing detection circuit provided by another embodiment of the present invention, wherein Vin is the input voltage corresponding to the sampling signal, Vout is the voltage sampling signal obtained after being superimposed on the DC reference voltage and amplified by the amplification unit, and Vcross is the zero-crossing sampling signal output by the second operational amplifier A2 through comparison processing based on the voltage sampling signal and the DC reference voltage. It can be seen that the voltage sampling signal is raised by a DC reference voltage relative to the sampling signal. For example, Figure 5In the figure, the center point of the sampling signal fluctuation (the vertical coordinate of the zero point) is 0, and the center point of the voltage sampling signal fluctuation is 2.5, that is, the voltage sampling signal is raised by 2.5V relative to the sampling signal, and the zero-crossing sampling signal Vcross converts the sine wave of the voltage sampling signal into a square wave. The rising and falling edges of the square wave signal are both zero-crossing signals, thereby realizing low-power zero-crossing signal sampling of the AC voltage input signal, effectively reducing the sampling power consumption of high voltage and zero-crossing signals.

[0080] In some embodiments, reference Figure 5 By comparing the input voltage Vin corresponding to the sampling signal and the voltage sampling signal Vout obtained after being superimposed on the DC reference voltage and amplified by the amplification unit, it can be seen that the signal output by the circuit has a fixed 90-degree phase shift. Since the signal output by the circuit has a fixed 90-degree phase shift, the circuit needs to be phase corrected. However, since the position where the voltage sampling signal Vout reaches the maximum or minimum value corresponds to the zero-crossing point position of the input voltage Vin, the signal Vout after voltage sampling and amplification of the input voltage can be sampled and judged. When the voltage sampling signal Vout reaches the maximum or minimum value, this moment is determined as the zero-crossing point of the input voltage Vin and recorded, thereby completing the zero-crossing signal sampling process.

[0081] In some embodiments, reference Figure 6 , Figure 6 2 is a circuit diagram of a zero-crossing detection circuit with a phase shift unit 220 provided in another embodiment of the present invention. The zero-crossing detection circuit also includes a phase shift unit arranged between the amplifying unit and the comparing unit. The phase shift unit is used to perform a 90° phase shift on the output signal of the amplifying unit to solve the problem of Figure 5 The problem is that the signal output by the circuit has a fixed 90 degree phase shift.

[0082] In some embodiments, to solve Figure 5 The signal output by the circuit has a fixed 90-degree phase shift. In addition to phase correction processing, the present application can also perform hardware processing on the output signal of the circuit by adding a phase shift unit.

[0083] refer to Figure 6The phase shift unit includes a third capacitor C3, a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12 and a third operational amplifier A3, the inverting end of the third operational amplifier A3 is connected to one end of the eleventh resistor R11 and one end of the twelfth resistor R12, the output end of the comparison unit is connected to one end of the third capacitor C3, the other end of the third capacitor C3 is connected to one end of the tenth resistor R10 and the in-phase end of the third operational amplifier A3, the other end of the eleventh resistor R11 is grounded, and one end of the twelfth resistor R12 is connected to the output end of the third operational amplifier A10, wherein the inverting end of the third operational amplifier A3 is grounded through the eleventh resistor R11, and the inverting end of the third operational amplifier A3 is connected to the voltage sampling signal obtained after being superimposed on the DC reference voltage and amplified by the amplification unit through the third capacitor C3, and then the voltage sampling signal output by the amplification unit is phase-shifted by 90°, so that the output signal of the circuit is hardware processed by the phase shift unit. Figure 4 A phase shift unit is added to the circuit to achieve a 90-degree phase shift of the voltage sampling signal, so that the second operational amplifier A2 can compare and process the voltage sampling signal with the DC reference voltage, and the output zero-crossing sampling signal Vcross does not need to be phase shifted, and its own zero-crossing point can be determined as the zero-crossing point of the input voltage Vin, thereby completing the zero-crossing signal sampling process, realizing low-power zero-crossing signal sampling of the AC voltage input signal, and effectively reducing the sampling power consumption of the high voltage and zero-crossing signals.

[0084] In some embodiments, reference Figure 6 The comparison unit includes a second operational amplifier A2 and a ninth resistor R9, the output end of the phase shift unit is connected to the in-phase end of the second operational amplifier A2, the inverting end of the second operational amplifier A2 is grounded, the output end of the second operational amplifier A2 is connected to one end of the ninth resistor R9, and the other end of the ninth resistor R9 is grounded, wherein, in the case where the zero-crossing detection circuit has a phase shift unit, the in-phase end of the second operational amplifier A2 receives the voltage sampling signal Vout1 after phase shifting, and the inverting end of the second operational amplifier A2 is grounded and connected to the output end of the second operational amplifier A2 through the ninth resistor R9, so that the output zero-crossing sampling signal Vcross does not need to be phase shifted again, and its own zero-crossing point can be determined as the zero-crossing point of the input voltage Vin, thereby completing the zero-crossing signal sampling process, realizing low-power zero-crossing signal sampling of the AC voltage input signal, and effectively reducing the sampling power consumption of the high voltage voltage and the zero-crossing signal.

[0085] In some embodiments, reference Figure 7 , Figure 7 It is another circuit diagram of a zero-crossing detection circuit with a phase shifting unit provided by another embodiment of the present invention. The phase shifting unit also includes a thirteenth resistor R13. The output end of the third operational amplifier A3 is grounded through the thirteenth resistor R13, which plays a role in stabilizing and dividing the voltage, so that the output voltage sampling signal Vout1 after the phase shift is more stable.

[0086] In some embodiments, Figure 7 The comparison unit includes a ninth resistor R9 and a second operational amplifier A2, the output end of the voltage reference unit is connected to the inverting end of the second operational amplifier A2, the output end of the amplification unit is connected to the non-inverting end of the second operational amplifier A2, the output end of the second operational amplifier A2 is connected to one end of the ninth resistor R9, and the other end of the ninth resistor R9 is grounded.

[0087] In some embodiments, Figure 7 The comparison unit includes a second operational amplifier A2 and a ninth resistor R9, the output end of the phase shift unit is connected to the in-phase end of the second operational amplifier A2, the inverting end of the second operational amplifier A2 is grounded, the output end of the second operational amplifier A2 is connected to one end of the ninth resistor R9, and the other end of the ninth resistor R9 is grounded.

[0088] In some embodiments, reference Figure 8 , Figure 8 It is another working waveform diagram of the zero-crossing detection circuit provided by another embodiment of the present invention, wherein Vin is the input voltage corresponding to the sampling signal, Vout1 is the voltage sampling signal after the phase shift unit is phase-shifted, and Vcross is the zero-crossing sampling signal output by the second operational amplifier A2 through comparison processing based on the voltage sampling signal Vout1 after the phase shift unit is phase-shifted. It can be seen that the voltage sampling signal Vout1 after the phase shift unit is phase-shifted is consistent with the center point of the sampling signal Vin fluctuation, and the phase is consistent, so the zero-crossing sampling signal Vcross converts the sine wave of the voltage sampling signal Vout1 after the phase shift unit is phase-shifted into a square wave, and the rising edge and falling edge of the square wave signal are both zero-crossing signals, thereby realizing low-power zero-crossing signal sampling of the AC voltage input signal, and effectively reducing the sampling power consumption of the high voltage and the zero-crossing signal.

[0089] See also Fig. 9 The third aspect of the present invention provides a method for obtaining a zero-crossing signal, which is applied to a zero-crossing detection circuit in which a phase shift unit is not provided in the second aspect of the present invention. The method for obtaining a zero-crossing signal includes but is not limited to the following steps S910 to S920:

[0090] Step S910: determining a signal period according to a time interval between two adjacent rising edges or a time interval between two adjacent falling edges in a comparison signal;

[0091] Step S920: delay the rising edge signal and the falling edge signal in the comparison signal by one quarter of the signal period respectively to obtain a zero-crossing signal.

[0092] According to the zero-crossing signal acquisition method provided by an embodiment of the present invention, since the sampling unit is provided with a first capacitor and a second capacitor, there is a 90-degree phase shift between the voltage sampling signal output by the amplification unit and the comparison signal output by the comparison unit and the AC voltage input from the AC voltage input unit. Therefore, the signal period is first determined from the comparison signal, and then the rising edge signal and the falling edge signal in the comparison signal are delayed by one quarter of the signal period, so that an accurate zero-crossing signal can be obtained.

[0093] The fourth aspect of the present application also provides a circuit board, including the voltage isolation sampling circuit of any embodiment of the first aspect of the present application or the zero-crossing detection circuit of any embodiment of the second aspect of the present application. The circuit board implements the various embodiments of the voltage isolation sampling circuit and the zero-crossing detection circuit in the present invention by running the voltage isolation sampling circuit and the zero-crossing detection circuit. At the same time, the beneficial effects of the voltage isolation sampling circuit and the zero-crossing detection circuit in the above-mentioned embodiments are achieved, and the voltage signal sampling of the AC voltage input signal with low power consumption is realized, and the zero-crossing signal sampling of the AC voltage input signal with low power consumption is realized, and the sampling power consumption of the high voltage and the zero-crossing signal is effectively reduced.

[0094] The fifth aspect of the present application provides an electrical device, including a circuit board of any one of the embodiments of the third aspect of the present application. The electrical device implements the various embodiments of the voltage isolation sampling circuit and the zero-crossing detection circuit in the present invention by running the voltage isolation sampling circuit and the zero-crossing detection circuit in the circuit board. At the same time, the beneficial effects of the voltage isolation sampling circuit and the zero-crossing detection circuit in the above-mentioned embodiments are achieved, and the voltage signal sampling of the low-power AC voltage input signal and the zero-crossing signal sampling of the low-power AC voltage input signal are realized, thereby effectively reducing the sampling power consumption of the high voltage and the zero-crossing signal.

[0095] The device embodiments described above are merely illustrative, and the units described as separate components may or may not be physically separated, that is, they may be located in one place or distributed on multiple network nodes. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0096] It will be appreciated by those skilled in the art that all or some of the steps and systems in the disclosed methods above may be implemented as software, firmware, hardware and appropriate combinations thereof. Some physical components or all physical components may be implemented as software executed by a processor, such as a central processing unit, a digital signal processor or a microprocessor, or implemented as hardware, or implemented as an integrated circuit, such as an application specific integrated circuit. Such software may be distributed on a computer-readable medium, which may include a computer storage medium or a non-transitory medium and a communication medium or a temporary medium. As known to those skilled in the art, the term computer storage medium includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information such as computer-readable instructions, data structures, program modules or other data. Computer storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disk DVD or other optical disk storage, magnetic cassettes, magnetic tapes, disk storage or other magnetic storage devices, or any other medium that may be used to store desired information and may be accessed by a computer. Furthermore, it is well known to those skilled in the art that communication media typically embodies computer readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transport mechanism, and may include any information delivery media.

[0097] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in the technical field without departing from the purpose of the present invention.

Claims

1. A voltage isolation sampling circuit, characterized in that: include: An AC voltage input unit, comprising a first AC input terminal and a second AC input terminal; A sampling unit, comprising a first capacitor, a sampling device and a second capacitor, wherein the first AC input terminal, the first capacitor, the sampling device, the second capacitor and the second AC input terminal are connected in sequence, and two ends of the sampling device are used to output a sampling signal; A voltage reference unit, used for providing a DC reference voltage; The amplifier unit, the output end of the voltage reference unit and the two ends of the sampling device are connected to the input end of the amplifier unit, and the amplifier unit is used to raise the zero point of the sampling signal to the DC reference voltage to output a voltage sampling signal.

2. The voltage isolation sampling circuit according to claim 1, characterized in that: The sampling device includes a first resistor connected between the first capacitor and the second capacitor.

3. The voltage isolation sampling circuit according to claim 1, characterized in that: The amplification unit includes a first operational amplifier, two ends of the sampling device are respectively connected to the non-inverting terminal and the inverting terminal of the first operational amplifier, and the output end of the voltage reference unit is connected to the non-inverting terminal of the first operational amplifier.

4. The voltage isolation sampling circuit according to claim 3, characterized in that: The amplification unit also includes a second resistor, a third resistor, a fourth resistor and a fifth resistor, one end of the sampling device is connected to one end of the second resistor, the output end of the voltage reference unit is connected to one end of the third resistor, the other ends of the second resistor and the third resistor are connected to the non-inverting end of the first operational amplifier; the other end of the sampling device is connected to one end of the fourth resistor, the other end of the fourth resistor is connected to the inverting end of the first operational amplifier and is connected to the output end of the first operational amplifier through the fifth resistor.

5. The voltage isolation sampling circuit according to claim 1, characterized in that: The voltage reference unit includes a three-terminal controllable voltage-stabilizing source and a sixth resistor, one end of the sixth resistor is connected to a DC power supply terminal, the other end of the sixth resistor is connected to a negative electrode and a reference electrode of the three-terminal controllable voltage-stabilizing source, the positive electrode of the three-terminal controllable voltage-stabilizing source is grounded, and the reference electrode of the three-terminal controllable voltage-stabilizing source serves as the output end of the voltage reference unit.

6. The voltage isolation sampling circuit according to claim 3, characterized in that: It also includes a seventh resistor and an eighth resistor, the output end of the first operational amplifier is connected to one end of the seventh resistor, the other end of the seventh resistor is connected to one end of the eighth resistor and is used to output the voltage sampling signal, and the other end of the eighth resistor is grounded.

7. A zero-crossing detection circuit, characterized in that: It comprises a comparison unit and the voltage isolation sampling circuit according to any one of claims 1 to 6, wherein the output end of the amplification unit is connected to the input end of the comparison unit, and the comparison unit is used to output a comparison signal with a zero-crossing signal.

8. The zero-crossing detection circuit according to claim 7, characterized in that: The comparison unit includes a second operational amplifier and a ninth resistor, the output end of the amplification unit is connected to the non-inverting end of the second operational amplifier, the output end of the voltage reference unit is connected to the inverting end of the second operational amplifier, the output end of the second operational amplifier is connected to one end of the ninth resistor, and the other end of the ninth resistor is grounded.

9. The zero-crossing detection circuit according to claim 7, characterized in that: It also includes a phase shift unit arranged between the amplifying unit and the comparing unit, and the phase shift unit is used to perform a 90° phase shift on the output signal of the amplifying unit.

10. The zero-crossing detection circuit according to claim 9, characterized in that: The phase shift unit includes a third capacitor, a tenth resistor, an eleventh resistor, a twelfth resistor and a third operational amplifier, the output end of the comparison unit is connected to one end of the third capacitor, the other end of the third capacitor is connected to one end of the tenth resistor and the non-inverting end of the third operational amplifier, the inverting end of the third operational amplifier is connected to one end of the eleventh resistor and one end of the twelfth resistor, the other end of the eleventh resistor is grounded, and one end of the twelfth resistor is connected to the output end of the third operational amplifier.

11. The zero-crossing detection circuit according to claim 10, characterized in that: The comparison unit includes a second operational amplifier and a ninth resistor, the output end of the phase shift unit is connected to the non-inverting end of the second operational amplifier, the inverting end of the second operational amplifier is grounded, the output end of the second operational amplifier is connected to one end of the ninth resistor, and the other end of the ninth resistor is grounded.

12. The zero-crossing detection circuit according to claim 10, characterized in that: The phase shift unit further includes a thirteenth resistor, and the output end of the third operational amplifier is grounded through the thirteenth resistor.

13. A method for acquiring a zero-crossing signal, applied to the zero-crossing detection circuit according to any one of claims 7 to 8, characterized in that: include: Determine a signal period according to a time interval between two adjacent rising edges or a time interval between two adjacent falling edges in the comparison signal; The rising edge signal and the falling edge signal in the comparison signal are respectively delayed by one quarter of the signal period to obtain a zero-crossing signal.

14. A circuit board, characterized in that: The invention comprises the voltage isolation sampling circuit as described in any one of claims 1 to 6 or the zero-crossing detection circuit as described in any one of claims 7 to 12.

15. An electrical device, characterized in that: Including the circuit board described in claim 14.

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