Zero crossing point detection circuit based on high-precision voltage sampling and energy router

Abstract

The utility model relates to the technical field of photovoltaic energy storage, in particular to a zero crossing point detection circuit based on high-precision voltage sampling and an energy router. The zero crossing point detection circuit comprises a phase voltage sampling circuit constructed based on a first operational amplifier U1A, and the phase voltage sampling circuit carries out sampling output based on a first reference voltage value, the voltage of a single-phase live wire and the voltage of a zero wire. The sampling output of the phase voltage sampling circuit is the sum of the set multiple of the difference value of the voltage of the single-phase live wire and the voltage of the zero line and a first reference voltage value; and the zero-cross detection circuit is constructed based on a second operational amplifier U2A and is used for comparing the sampling output of the phase voltage sampling circuit with a second reference voltage value and outputting a zero-cross signal. The energy router is provided with the zero crossing point detection circuit. According to the utility model, a phase voltage sampling link and a zero crossing point detection link can be integrated, and the circuit complexity is simplified.

Description

Technical Field

[0001] The utility model relates to the technical field of photovoltaic energy storage, and in particular to a zero-crossing detection circuit and an energy router based on high-precision voltage sampling. Background Art

[0002] Zero crossing refers to the moment or position when the sinusoidal AC voltage or current changes to zero voltage or zero current (the positive half cycle decreases from positive to zero or the negative half cycle increases from negative to zero). The relay switches on and off at the zero crossing, which can reduce the arcing effect of the relay at the moment of switching on and off, and realize the long life protection of the relay.

[0003] In order to ensure that the relay is turned on and off at the zero-crossing point, the existing technical solutions are generally as follows: one is the thyristor switch, which uses a thyristor switch instead of a relay, or uses a thyristor switch and a relay in parallel, and controls the on-off timing of the two to realize the opening and closing of the relay under zero voltage difference. However, due to the shortcomings of mis-conduction and mis-shutdown of the thyristor switch, the reliability of this solution is low; the second is the zero-crossing detection circuit, which combines the zero-crossing detection circuit with the microcontroller MCU to enable the relay to complete the on-off operation at the voltage zero crossing, but most of the detection circuits use a simple form of resistors and optocouplers in series, which leads to inaccurate detection. Utility Model Content

[0004] The utility model provides a zero-crossing detection circuit and an energy router based on high-precision voltage sampling, which can solve the problem of inaccurate detection in existing zero-crossing detection circuits and avoid the reduction of detection accuracy due to fluctuation of the voltage of the corresponding phase at the zero-crossing point.

[0005] According to a zero-crossing detection circuit based on high-precision voltage sampling of the utility model, it includes:

[0006] A phase voltage sampling circuit constructed based on the first operational amplifier U1A, the phase voltage sampling circuit performs sampling and output based on the first reference voltage value, the voltage of the single-phase live wire and the voltage of the neutral wire, and the sampling output of the phase voltage sampling circuit is the sum of a set multiple of the difference between the voltage of the single-phase live wire and the voltage of the neutral wire and the first reference voltage value; and

[0007] The zero-crossing detection circuit is constructed based on the second operational amplifier U2A, and is used to compare the sampling output of the phase voltage sampling circuit with the second reference voltage value and output a zero-crossing signal.

[0008] Preferably, the non-phase input terminal of the first operational amplifier U1A samples the voltage of the neutral line through a first processing circuit, and the inverting input terminal of the first operational amplifier U1A samples the voltage of the single-phase live line through a second processing circuit; the first processing circuit has a first capacitor C1 for serially connecting the neutral line, and the second processing circuit has a second capacitor C2 for serially connecting the single-phase live line.

[0009] Preferably, the first processing circuit includes a first resistor connected in series with the first capacitor C1, the second processing circuit includes a second resistor connected in series with the second capacitor C2, and a feedback resistor R16 is connected in series between the output terminal of the first operational amplifier U1A and the inverting input terminal of the first operational amplifier U1A; the first resistor and the second resistor have the same resistance value, and the resistance value of the feedback resistor R16 is smaller than the resistance value of the second resistor.

[0010] Preferably, the first resistor is formed by a plurality of resistors connected in series, and the second resistor is formed by a plurality of resistors connected in series.

[0011] Preferably, the non-inverting input terminal of the first operational amplifier U1A inputs the first reference voltage value through a reference voltage circuit, the reference voltage circuit includes a resistor R8 and a capacitor C3 connected in parallel, one end of the resistor R8 and the capacitor C3 are simultaneously connected to the ground terminal, and the other end of the resistor R8 and the capacitor C3 inputs the first reference voltage value.

[0012] Preferably, the inverting input terminal of the second operational amplifier U2A is connected to the sampling output of the phase voltage sampling circuit, and the non-inverting input terminal of the second operational amplifier U2A is connected to the second reference voltage value.

[0013] Preferably, the non-inverting input terminal of the second operational amplifier U2A is connected to the second reference voltage value through a capacitor C8 and a resistor R19 connected in parallel; a diode D2 is connected between the output terminal and the non-inverting input terminal of the second operational amplifier U2A, and a resistor R20 is also connected in series to the diode D2.

[0014] Preferably, the output terminal of the second operational amplifier U2A is connected to a pull-up voltage.

[0015] Preferably, the first reference voltage value and the second reference voltage value have the same value.

[0016] An energy router according to the utility model includes any one of the above-mentioned zero-crossing detection circuits based on high-precision voltage sampling.

[0017] The utility model has the following beneficial effects:

[0018] The zero-crossing detection circuit disclosed in the present invention can integrate the phase voltage sampling link and the zero-crossing detection link, so that the circuit complexity can be simplified; wherein, the output end of the phase voltage sampling circuit can output the phase voltage acquisition signal, and the output end of the zero-crossing detection circuit can output the zero-crossing detection signal. The zero-crossing detection circuit disclosed in the present invention can perform zero-crossing detection based on the output of the phase voltage sampling circuit, and through the first operational amplifier U1A and the first reference voltage value, it can avoid the reduction of detection accuracy caused by the voltage of the corresponding phase fluctuating at the zero-crossing point. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a circuit diagram of the zero-crossing detection circuit in Example 1;

[0020] Figure 2 is a timing diagram of the output signal of the zero-crossing detection circuit in Example 1;

[0021] Figure 3 This is a timing diagram of the output signal of the zero-crossing detection circuit in Example 1 after the hysteresis link is removed. DETAILED DESCRIPTION

[0022] In order to further understand the content of the utility model, the utility model is described in detail in conjunction with the embodiments. It should be understood that the embodiments are only used to explain the utility model but not to limit it. Example 1

[0023] In order to reduce the arcing effect of the relay at the moment of switching on and off and realize the long life protection of the relay, a zero-crossing detection circuit based on high-precision voltage sampling is disclosed in one embodiment of the utility model.

[0024] The zero-crossing detection circuit disclosed in this embodiment can integrate a phase voltage sampling circuit and a zero-crossing detection circuit. It can greatly improve the accuracy of zero-crossing sampling in order to solve the problems of low detection accuracy in the current zero-crossing detection circuit in which a resistor and an optocoupler are connected in series, and the problem of easy jitter and weak anti-interference ability in the zero-crossing detection circuit in which an operational amplifier comparator and a resistor voltage divider circuit are connected in series.

[0025] See Figure 1 , is a zero-crossing detection circuit based on high-precision voltage sampling disclosed in this embodiment, having:

[0026] A phase voltage sampling circuit constructed based on the first operational amplifier U1A, the phase voltage sampling circuit performs sampling and output based on the first reference voltage value, the voltage of the single-phase live wire and the voltage of the neutral wire, and the sampling output of the phase voltage sampling circuit is the sum of a set multiple of the difference between the voltage of the single-phase live wire and the voltage of the neutral wire and the first reference voltage value; and

[0027] A zero-crossing detection circuit constructed based on the second operational amplifier U2A, the zero-crossing detection circuit is used to compare the sampled output of the phase voltage sampling circuit with the second reference voltage value and output a zero-crossing signal;

[0028] The first reference voltage value and the second reference voltage value have the same value (both are +1.5V in this embodiment).

[0029] Based on the above, the zero-crossing detection circuit disclosed in the present invention can integrate the phase voltage sampling link and the zero-crossing detection link, so that the circuit complexity can be simplified; wherein, the output end of the phase voltage sampling circuit can output the phase voltage acquisition signal, and the output end of the zero-crossing detection circuit can output the zero-crossing detection signal. The zero-crossing detection circuit disclosed in the present invention can perform zero-crossing detection based on the output of the phase voltage sampling circuit, and through the first operational amplifier U1A and the first reference voltage value, it can avoid the reduction of detection accuracy caused by the voltage of the corresponding phase fluctuating at the zero-crossing point.

[0030] Among them, the positive input terminal of the first operational amplifier U1A samples the voltage of the neutral line through the first processing circuit, and the negative input terminal of the first operational amplifier U1A samples the voltage of the single-phase live line through the second processing circuit; the first processing circuit has a first capacitor C1 for serially connecting the neutral line, and the second processing circuit has a second capacitor C2 for serially connecting the single-phase live line. The first capacitor C1 and the second capacitor C2 can be used as DC blocking capacitors to isolate and filter the DC signal in the input AC signal, thereby preferably improving the sampling output accuracy of the phase voltage sampling circuit, which is conducive to improving the accuracy of zero-crossing point detection.

[0031] The first processing circuit includes a first resistor connected in series with the first capacitor C1, the second processing circuit includes a second resistor connected in series with the second capacitor C2, and a feedback resistor R16 is connected in series between the output end of the first operational amplifier U1A and the inverting input end of the first operational amplifier U1A; the first resistor and the second resistor have the same resistance value, and the resistance value of the feedback resistor R16 is smaller (much smaller) than the resistance value of the second resistor. This enables the feedback resistor R16 and the second resistor to form a proportional output circuit, and the first resistor can act as a balancing resistor, thereby better realizing the acquisition and output of the phase voltage.

[0032] The first resistor is formed by connecting a plurality of resistors in series (resistors R1-R7 in this embodiment), and the second resistor is formed by connecting a plurality of resistors in series (resistors R9-R15 in this embodiment). This facilitates implementation.

[0033] That is, the sampling output of the sampling terminal G_L1N_VOL of the first operational amplifier U1A The difference between the voltage of the single-phase live wire and the voltage of the neutral wire Has the following relationship,

[0034]

[0035] The first operational amplifier U1A inputs the first reference voltage value through the reference voltage circuit, and the reference voltage circuit includes a resistor R8 and a capacitor C3 connected in parallel, one end of the resistor R8 and the capacitor C3 are connected to the ground terminal at the same time, and the other end of the resistor R8 and the capacitor C3 inputs the first reference voltage value, thereby preferably realizing the addition of the first reference voltage value.

[0036] The positive power input terminal of the first operational amplifier U1A is connected to a +5V voltage and is grounded through a capacitor C5 , and the negative power input terminal of the first operational amplifier U1A is grounded.

[0037] The output terminal of the first operational amplifier U1A is connected to the output resistor R17, and the output resistor R17 and the sampling terminal G_L1N_VOL are grounded via a capacitor C6, thereby achieving the output of the phase voltage acquisition signal.

[0038] A capacitor C4 is also connected in parallel to the feedback resistor R16.

[0039] In this embodiment, the inverting input terminal of the second operational amplifier U2A is connected to the sampling output of the phase voltage sampling circuit, and the non-inverting input terminal of the second operational amplifier U2A is connected to the second reference voltage value, thereby preferably achieving an increase in the second reference voltage value.

[0040] The inverting input terminal of the second operational amplifier U2A is connected to the sampling output of the sampling circuit through the resistor R18, and the inverting input terminal of the second operational amplifier U2A is also grounded through the capacitor C7 and the diode D1.

[0041] Among them, the non-inverting input terminal of the second operational amplifier U2A is connected to the second reference voltage value through the capacitor C8 and the resistor R19 connected in parallel; the diode D2 is connected between the output terminal and the non-inverting input terminal of the second operational amplifier U2A, and the resistor R20 is also connected in series at the diode D2. Based on the above, the capacitor C8, the resistor R19, the resistor R20 and the diode D2 can constitute a hysteresis link, so as to ensure that the output of the zero-crossing detection circuit is not affected by the fluctuation of the AC voltage signal at the zero-crossing point, thereby improving the accuracy and anti-interference performance of the zero-crossing detection. In addition, by utilizing the forward conduction characteristic of the diode D2, the second reference voltage value can form two different thresholds at the non-inverting input terminal of the second operational amplifier U2A (that is, when there is no signal output at the output terminal of the second operational amplifier U2A, the threshold is the second reference voltage value; when there is a signal output at the output terminal of the second operational amplifier U2A, the threshold is the second reference voltage value minus the conduction voltage of the diode D2), and the two different thresholds can be switched at the moment when the zero-crossing detection signal flips, thereby reducing the influence of the fluctuation of the AC voltage signal and effectively improving the accuracy of zero-crossing detection.

[0042] See Figure 2 and 3 , when there is no hysteresis link, the output of the zero-crossing detection circuit has obvious and large fluctuations at both the rising and falling edges.

[0043] In this embodiment, the output terminal of the second operational amplifier U2A is connected to a pull-up voltage (+3.3V in this embodiment). Thus, the waveform output of the zero-crossing detection signal is preferably achieved. That is, a data processing device such as a microcontroller MCU can use the moment when the zero-crossing signal output terminal G_L1N_F jumps from a high level (3.3V) to a low level (0V) as the zero-crossing point.

[0044] The output end of the second operational amplifier U2A is connected to the pull-up voltage through the resistor R22, and the output end of the second operational amplifier U2A is connected in series with the resistor R21 to form the zero-crossing output end GRID_L1N_F, and the zero-crossing output end GRID_L1N_F is grounded through the capacitor C10.

[0045] The positive power input terminal of the second operational amplifier U2A is connected to a +5V voltage and is grounded through a capacitor C9; the negative power input terminal of the second operational amplifier U2A is grounded.

[0046] As a specific embodiment, the model of the first operational amplifier U1A can be TLV9064IPWR, and the model of the second operational amplifier U2A can be LM2903DR; the voltage values ​​of the first reference voltage value and the second reference voltage value can both be +1.5V; the first capacitor C1 and the second capacitor C2 can both be 1812 ceramic capacitors with a withstand voltage of 2KV and a capacitance of 10nF; the resistance values ​​of the resistors R1-R6 and the resistors R9-R14 are all 1 megohm, The resistance values ​​of resistors R7 and R15 are both 49.9 kilohms, the resistance value of feedback resistor R16 is 20 kilohms; the resistance value of resistor R8 is 20 kilohms, the capacitance value of capacitor C3 is 1nF (1nF / 50V / 0603); the capacitance value of capacitor C5 is 100nF (100nF / 50V / 0603); the resistance value of output resistor R17 is 100 ohms (100ohm / 0603), the capacitance value of capacitor C6 is 10nF (10nF / 50V / 06 03); the capacitance value of capacitor C4 is 1nF (1nF / 50V / 0603); the capacitance value of capacitor C9 is 100nF (100nF / 50V / 0603); the resistance value of resistor R18 is 4.99 kilohms (4.99K / 0603), the capacitance value of capacitor C7 is 10nF (10nF / 50V / 0603), the model of diode D1 is BAT43W / SOD-123; the capacitance value of capacitor C8 is 1nF (1nF / 50V / 0603), the resistance of resistor R19 is 5.1 kilo ohms (5.1K / 0603); the model of diode D2 is BAT43W / SOD-123, the resistance of resistor R20 is 20 kilo ohms (20K / 0603); the resistance of resistor R21 is 499 ohms (499ohm / 0603), the resistance of resistor R22 is 5.1 kilo ohms (5.1K / 0603), and the capacitance of capacitor C10 is 10nF (10nF / 50V / 0603). Example 2

[0047] Based on the zero-crossing detection circuit based on high-precision voltage sampling disclosed in Example 1, this embodiment provides an energy router, which includes the zero-crossing detection circuit based on high-precision voltage sampling in Example 1.

[0048] Specifically, an energy router disclosed in this embodiment can have:

[0049] A green energy input port, which is used to connect to the green energy power supply system to form a green energy branch, and is connected to the load output port through the first relay group;

[0050] A mains input port, which is used to connect to the power supply system of the power grid to form a power grid branch, and to connect to the load output port through the second relay group; and

[0051] The load output port is used to connect to the user's load circuit to form a load branch, and the load branch is powered by the green energy branch and / or the power grid branch; wherein the green energy branch and the power grid branch are two different power supply branches.

[0052] Among them, a zero-crossing point detection circuit based on high-precision voltage sampling in Example 1 can be arranged between the live wire and the neutral wire of the green energy input port and the mains power input port.

[0053] The above is a schematic description of the present invention and its implementation methods, which is not restrictive. The embodiments shown are only part of the implementation methods of the present invention, and the actual structure is not limited thereto. Therefore, if ordinary technicians in this field are inspired by it and design structural methods and embodiments similar to the technical solution without creativity without departing from the purpose of the invention of the present invention, they should all fall within the protection scope of the present invention.

Claims

1. A zero-crossing detection circuit based on high-precision voltage sampling, characterized in that: include A phase voltage sampling circuit constructed based on the first operational amplifier U1A performs sampling and output based on the first reference voltage value, the voltage of the single-phase live wire and the voltage of the neutral wire. The sampling output of the phase voltage sampling circuit is the sum of a set multiple of the difference between the voltage of the single-phase live wire and the voltage of the neutral wire and the first reference voltage value; as well as The zero-crossing detection circuit is constructed based on the second operational amplifier U2A, and is used to compare the sampling output of the phase voltage sampling circuit with the second reference voltage value and output a zero-crossing signal.

2. A zero-crossing detection circuit based on high-precision voltage sampling according to claim 1, characterized in that: The non-phase input terminal of the first operational amplifier U1A samples the voltage of the neutral line through the first processing circuit, and the inverting input terminal of the first operational amplifier U1A samples the voltage of the single-phase live line through the second processing circuit; the first processing circuit has a first capacitor C1 for connecting the neutral line in series, and the second processing circuit has a second capacitor C2 for connecting the single-phase live line in series.

3. A zero-crossing detection circuit based on high-precision voltage sampling according to claim 2, characterized in that: The first processing circuit includes a first resistor connected in series with the first capacitor C1, the second processing circuit includes a second resistor connected in series with the second capacitor C2, and a feedback resistor R16 is connected in series between the output terminal of the first operational amplifier U1A and the inverting input terminal of the first operational amplifier U1A; the first resistor and the second resistor have the same resistance value, and the resistance value of the feedback resistor R16 is much smaller than the resistance value of the second resistor.

4. A zero-crossing detection circuit based on high-precision voltage sampling according to claim 3, characterized in that: The first resistor is formed by connecting a plurality of resistors in series, and the second resistor is formed by connecting a plurality of resistors in series.

5. A zero-crossing detection circuit based on high-precision voltage sampling according to claim 4, characterized in that: The non-inverting input terminal of the first operational amplifier U1A inputs the first reference voltage value through the reference voltage circuit. The reference voltage circuit includes a resistor R8 and a capacitor C3 connected in parallel. One end of the resistor R8 and the capacitor C3 is connected to the ground terminal at the same time, and the other end of the resistor R8 and the capacitor C3 inputs the first reference voltage value.

6. A zero-crossing detection circuit based on high-precision voltage sampling according to claim 5, characterized in that: The inverting input terminal of the second operational amplifier U2A is connected to the sampling output of the phase voltage sampling circuit, and the non-inverting input terminal of the second operational amplifier U2A is connected to the second reference voltage value.

7. A zero-crossing detection circuit based on high-precision voltage sampling according to claim 6, characterized in that: The non-inverting input terminal of the second operational amplifier U2A is connected to the second reference voltage value through a capacitor C8 and a resistor R19 connected in parallel; a diode D2 is connected between the output terminal and the non-inverting input terminal of the second operational amplifier U2A, and a resistor R20 is also connected in series to the diode D2.

8. The zero-crossing detection circuit based on high-precision voltage sampling according to claim 7, characterized in that: The output terminal of the second operational amplifier U2A is connected to a pull-up voltage.

9. The zero-crossing detection circuit based on high-precision voltage sampling according to claim 1, characterized in that: The first reference voltage value and the second reference voltage value have the same value.

10. An energy router, characterized in that: It comprises a zero-crossing detection circuit based on high-precision voltage sampling as described in any one of claims 1-9.

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