Power grid voltage detection circuit, system and chip

Abstract

The invention provides a power grid voltage detection circuit, system and chip. In the power grid voltage detection circuit, one side of a high-voltage isolation module is connected to a power grid live wire and a power grid zero wire which are connected with a control switch, and the other side of the high-voltage isolation module is connected with a first node detection module, a voltage detection module and a second node detection module; the first node detection module, the second node detection module and the voltage detection module are respectively connected with the node selection module; when alternating current exists in the power grid, the voltage detection module detects the power-on states of the power grid live wire and the power grid zero wire through the high-voltage isolation module, and the power-on states represent the sequential relation of voltage input signals on the power grid live wire and the power grid zero wire when the control switch switches the state. Therefore, the node selection module is controlled to select an enabling object in the first node detection module and the second node detection module to detect the impedance at the node so as to judge the on-off state of the control switch, so that when a plurality of power grid voltage detection circuits are connected in parallel, the nodes are conveniently and uniformly detected, and the circuit reliability is improved.

Description

Technical Field

[0001] The present invention relates to the field of circuits, and in particular to a power grid voltage detection circuit, system and chip. Background Art

[0002] In an AC power supply system, the neutral line and the live line in the AC power grid are output after passing through a full-phase rectifier bridge, wherein the voltage at the positive output end of the rectifier bridge is high, and the voltage at the negative output end of the rectifier bridge is low.

[0003] If you need to detect the switch state between the neutral and live wires, and determine whether the impedance between the live and neutral wires is in a high-resistance state (corresponding to the switch being turned off) or a low-resistance state (corresponding to the switch being turned on), the usual practice is to place the detection module at one of the nodes and detect the voltage or current at the node. However, in some special applications, after two or more systems are connected to the AC power grid at the same time, since there is a path between the node detection modules of different systems, if the detection nodes of different systems are connected to two different high-voltage input terminals, the node detection modules of the entire system will fail. Therefore, the nodes to be detected need to be unified. However, in customer use, the end user cannot understand whether the detection node is placed on the neutral or live wire.

[0004] Therefore, a technical solution is needed so that the detection nodes can be changed according to customer usage when the product is processed and used at the terminal, and the detection nodes can be unified when multiple systems or circuits are used in parallel to obtain stable detection results. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a power grid voltage detection circuit, comprising: a high voltage isolation module, a first node detection module, a second node detection module, a voltage detection module, and a node selection module; The first input end of the high-voltage isolation module is used to be electrically connected to the live wire of the power grid connected to the control switch, the second input end thereof is used to be electrically connected to the neutral wire of the power grid, the first output end thereof is electrically connected to the detection end of the first node detection module and the first detection end of the voltage detection module respectively, and the second output end thereof is electrically connected to the detection end of the second node detection module and the second detection end of the voltage detection module respectively; The enable terminal of the first node detection module is electrically connected to the first output terminal of the node selection module; The enable terminal of the second node detection module is electrically connected to the second output terminal of the node selection module; The output end of the voltage detection module is electrically connected to the input end of the node selection module; Wherein, when there is alternating current in the power grid, the voltage detection module detects the power-on state of the live wire and the neutral wire of the power grid through the voltage signal output by the high-voltage isolation module, and the power-on state represents the timing relationship of the voltage input signals on the live wire and the neutral wire of the power grid when the control switch is switched; The voltage detection module sends an enable signal to the first node detection module and the second node detection module respectively through the node selection module according to the timing relationship, so as to select an enabled object in the first node detection module and the second node detection module; The enabling object is used to detect the impedance of the node at the location to determine the on-off state of the control switch.

[0006] In a possible implementation, the high-voltage isolation module includes a first high-voltage isolation unit and a second high-voltage isolation unit; The input end and the output end of the first high-voltage isolation unit serve as the first input end and the first output end of the high-voltage isolation module respectively; The input end and the output end of the second high-voltage isolation unit serve as the second input end and the second output end of the high-voltage isolation module respectively.

[0007] In a possible implementation manner, the enable signals sent by the node selection module to the first node detection module and the second node detection module are opposite.

[0008] In a possible implementation, the timing relationship is the order in which high levels appear in the voltage input signal on the live line of the grid and the voltage input signal on the neutral line of the grid when the state of the control switch is switched from off to closed.

[0009] In a possible implementation, the timing relationship is the order in which high levels of the voltage input signal on the live line of the grid and the voltage input signal on the neutral line of the grid disappear when the state of the control switch is switched from closed to cutoff.

[0010] In a possible implementation manner, the node selection module is implemented based on an inverter.

[0011] In a possible implementation, a rectifier bridge is also included; The two AC input terminals of the rectifier bridge are respectively used to electrically connect the live wire of the power grid and the neutral wire of the power grid, the positive output terminal thereof serves as a power bus interface, and the negative output terminal thereof is grounded; The power bus interface is connected with a capacitor.

[0012] In a possible implementation, the high-voltage isolation module, the first node detection module, the second node detection module, the voltage detection module, and the node selection module are connected to a ground different from the ground to which the rectifier bridge is connected.

[0013] The present invention also provides a power grid voltage detection system, comprising a plurality of power grid voltage detection circuits as described above connected in parallel to the power grid.

[0014] The present invention also provides a power grid voltage detection chip, which internally encapsulates the power grid voltage detection circuit as described above.

[0015] The technical solution provided by the present invention has at least the following beneficial effects: By arranging a high-voltage isolation module in front of the first node detection module, the second node detection module and the voltage detection module, the high-voltage AC voltage supplied by the input power grid can be isolated and current-limited from the related modules used for low-voltage detection internally, thereby preventing the high-voltage signal from damaging the internal low-voltage detection circuit; at the same time, the first node detection module and the second node detection module, as two detection nodes in the power grid voltage detection circuit, can select specific detection nodes for detection in the first node detection module and the second node detection module according to customer usage, so that when multiple power grid voltage detection circuits are connected in parallel to the power grid for use, it is convenient to unify the specific detection nodes therein to the same power grid line, thereby improving the reliability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A first schematic diagram of a power grid voltage detection circuit provided by an embodiment of the present invention; Figure 2 A second schematic diagram of a power grid voltage detection circuit provided by an embodiment of the present invention; Figure 3 A first signal timing diagram between an AC voltage input signal, a control switch, a first node detection module and a second node detection module provided in an embodiment of the present invention; Figure 4 A second signal timing diagram between an AC voltage input signal, a control switch, a first node detection module and a second node detection module provided in an embodiment of the present invention; Figure 5 A schematic diagram of a node selection module provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0017] In order to deepen the understanding of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. The embodiments are only used to explain the present invention and do not limit the protection scope of the present invention.

[0018] Please refer to Figures 1 to 5, a power grid voltage detection circuit provided by the present invention includes: a high voltage isolation module, a first node detection module, a second node detection module, a voltage detection module, and a node selection module; The first input end of the high-voltage isolation module is used to be electrically connected to the live wire VL of the power grid connected to the control switch S1, the second input end thereof is used to be electrically connected to the neutral wire VN of the power grid, the first output end thereof is electrically connected to the detection end of the first node detection module and the first detection end of the voltage detection module respectively, and the second output end thereof is electrically connected to the detection end of the second node detection module and the second detection end of the voltage detection module respectively; The enable terminal of the first node detection module is electrically connected to the first output terminal of the node selection module; The enable terminal of the second node detection module is electrically connected to the second output terminal of the node selection module; The output end of the voltage detection module is electrically connected to the input end of the node selection module; Wherein, when there is alternating current Vac in the power grid, the voltage detection module detects the power-on state of the power grid live wire VL and the power grid neutral wire VN through the voltage signal output by the high-voltage isolation module, and the power-on state represents the timing relationship of the voltage input signals on the power grid live wire VL and the power grid neutral wire VN when the control switch S1 switches the state; The voltage detection module sends an enable signal to the first node detection module and the second node detection module respectively through the node selection module according to the timing relationship, so as to select an enabled object in the first node detection module and the second node detection module; The enabling object is used to detect the impedance of the node at the location to determine the on-off state of the control switch S1.

[0019] In this embodiment, the high-voltage isolation module can isolate and limit the high-voltage AC voltage supplied by the input power grid from the relevant modules used for low-voltage detection internally, so as to prevent the high-voltage signal from damaging the internal low-voltage detection circuit. The voltage detection module is used to detect the AC voltage signal output after the high-voltage isolation of the high-voltage isolation module, so as to judge the change of the voltage input signal VLin on the live wire VL of the power grid and the voltage input signal VNin on the neutral wire VN of the power grid, and send the corresponding control signal (for example, it can be a signal in the form of high and low levels) to the node selection module accordingly. The node selection module can be implemented based on a single or multiple inverters, and is used to output the corresponding enable signal according to the control signal. The first node detection module is arranged on the line where the live wire VL of the power grid is located, and the second node detection module is arranged on the line where the neutral wire VN of the power grid is located. The first node detection module and the second node detection module are node impedance detection modules of the same type, and the impedance detection of the corresponding node can be realized by detecting the voltage and current of the live wire VL of the power grid and the neutral wire VN of the power grid. The enable signal sent by the node selection module to the first node detection module can be regarded as the first enable signal EN1, and the enable signal sent to the second node detection module can be regarded as the second enable signal EN2. The first enable signal EN1 and the second enable signal EN2 are both signals in the form of high and low levels. The control switch S1 is connected in series between the AC power supply end and the grid voltage detection circuit. It should be noted that when multiple grid voltage detection circuits are connected in parallel to the grid for use, each grid voltage detection circuit is connected after the same control switch S1. Therefore, the time relationship of the high-voltage input signal is the same for each grid voltage detection circuit. Assuming that the initial state of multiple parallel grid voltage detection circuits selects different detection nodes, when the control switch S1 is closed, the sequence of the high-voltage input signal can obtain the same high-voltage detection result for multiple parallel grid voltage detection circuits after the same control switch S1, so the node on the same grid line (such as the grid live line VL or the grid neutral line VN) will be selected as the detection point of the node detection, avoiding the detection error caused by the different grid lines where the detection nodes are located, and improving the reliability of the detection.

[0020] In one possible implementation, Figure 2 , the high-voltage isolation module includes a first high-voltage isolation unit and a second high-voltage isolation unit; The input end and the output end of the first high-voltage isolation unit serve as the first input end and the first output end of the high-voltage isolation module respectively; The input end and the output end of the second high-voltage isolation unit serve as the second input end and the second output end of the high-voltage isolation module respectively.

[0021] In this embodiment, the first high-voltage isolation unit and the second high-voltage isolation unit are conventional high-voltage isolation units and can adopt conventional high-voltage isolation design.

[0022] In a possible implementation manner, the enable signals sent by the node selection module to the first node detection module and the second node detection module are opposite.

[0023] In this embodiment, the enable signal sent by the node selection module to the first node detection module can be regarded as the first enable signal EN1, and the enable signal sent to the second node detection module can be regarded as the second enable signal EN2. When the first enable signal EN1 is high level 1, the second enable signal EN2 is low level 0. When the first enable signal EN1 is low level 0, the second enable signal EN2 is high level 1.

[0024] In a possible implementation, the timing relationship is the order in which high levels appear in the voltage input signal VLin on the live line VL of the grid and the voltage input signal VNin on the neutral line VN of the grid when the state of the control switch S1 is switched from off to on.

[0025] In this embodiment, when there is AC power Vac in the power grid, if the control switch S1 is cut off, the voltage input signal VLin on the live line VL of the power grid and the voltage input signal VNin on the neutral line VN of the power grid are both at low levels. When the state of the control switch S1 is switched from cut off to closed, the node detection module on the power grid line that appears first or later in the voltage input signal VLin on the live line VL of the power grid and the voltage input signal VNin on the neutral line VN of the power grid is used as an enabled object. In a specific implementation, Figure 3 , when the control switch S1 is turned off, the first enable signal EN1 is high level 1, and the second enable signal EN2 is low level 0. When the state of the control switch S1 is switched from off to closed, the voltage input signal VNin on the neutral line VN of the power grid first appears at a high level, and the voltage input signal VLin on the live line VL of the power grid appears at a high level later, then the node selection module controls the first enable signal EN1 to switch to a low level 0, and the second enable signal EN2 to switch to a high level 1. The second node detection module is selected as the enable object in the first node detection module and the second node detection module. That is, the electrical signal of the power grid is detected by the second node detection module to determine the on-off state of the control switch S1. It should be pointed out that the level switching control of the first enable signal EN1 and the second enable signal EN2 by the node selection module has nothing to do with the initial levels of the first enable signal EN1 and the second enable signal EN2 when the control switch S1 is turned off.

[0026] In a possible implementation, the timing relationship is the order in which high levels of the voltage input signal VLin on the live line VL of the grid and the voltage input signal VNin on the neutral line VN of the grid disappear when the state of the control switch S1 is switched from closed to cutoff.

[0027] In this embodiment, when there is AC power Vac in the power grid, if the control switch S1 is closed, the voltage input signal VLin on the live line VL of the power grid and the voltage input signal VNin on the neutral line VN of the power grid both have periodic high levels. When the state of the control switch S1 is switched from closed to cut-off, the node detection module on the power grid line whose high level disappears first or later in the voltage input signal VLin on the live line VL of the power grid and the voltage input signal VNin on the neutral line VN of the power grid is used as an enabled object. In a specific implementation manner, Figure 4 , when the control switch S1 is closed, the first enable signal EN1 is low level 0, and the second enable signal EN2 is high level 1. When the state of the control switch S1 is switched from closed to cut-off, the high level of the voltage input signal VNin on the grid neutral line VN disappears later, and the high level of the voltage input signal VLin on the grid live line VL disappears first, then the node selection module controls the first enable signal EN1 to switch to high level 1, and the second enable signal EN2 to switch to low level 0. The first node detection module is selected as the enable object in the first node detection module and the second node detection module. That is, the electrical signal of the grid is detected by the first node detection module to determine the on-off state of the control switch S1. It should be pointed out that the level switching control of the first enable signal EN1 and the second enable signal EN2 by the node selection module has nothing to do with the initial levels of the first enable signal EN1 and the second enable signal EN2 when the control switch S1 is closed.

[0028] In one possible implementation, Figure 5 , the node selection module is implemented based on an inverter.

[0029] In this embodiment, the node selection module can be composed of two inverters connected in series, such as Figure 5 The input end of the first-stage inverter is electrically connected to the output end of the voltage detection module, and its output end is electrically connected to the enable end of the first node detection module and the input end of the second-stage inverter. The output end of the second-stage inverter is electrically connected to the enable end of the second node detection module.

[0030] In one possible implementation, Figure 1 , also includes a rectifier bridge BR; The two AC input terminals of the rectifier bridge BR are respectively used to electrically connect the live wire VL of the power grid and the neutral wire VN of the power grid, the positive output terminal thereof serves as a power bus interface VBUS, and the negative output terminal thereof is grounded; The power bus interface VBUS is connected to a capacitor C1.

[0031] In this embodiment, the rectifier bridge BR adopts a conventional model. The capacitor C1 adopts a conventional model, which can smooth the power supply voltage and reduce power supply noise and interference. When the control switch S1 is turned on, due to the rectification effect of the rectifier bridge BR, the reference ground of the power grid voltage detection circuit is the negative output end of the rectifier bridge BR, then the AC sinusoidal signal will appear at both ends of the power grid live wire VL and the power grid neutral wire VN. Specifically, when one of the high-voltage input terminals is positive, the other high-voltage input terminal is equivalent to the ground of the rectifier bridge, that is, the reference ground of the system is -0.7V, that is, the negative value of the forward conduction voltage of the diode of the rectifier bridge. When the switch is turned on, the voltage input signal VLin on the power grid live wire VL and the voltage input signal VNin on the power grid neutral wire VN are input to the voltage detection module after passing through the high-voltage isolation module. The high-voltage detection module will determine which input terminal first inputs the high voltage and which input terminal is -0.7V first. Then, according to different input high voltage timings, node detection modules (ie, the first node detection module and the second node detection module) of different nodes are enabled, thereby achieving the purpose of selecting nodes for detection circuits.

[0032] In a possible implementation, the high-voltage isolation module, the first node detection module, the second node detection module, the voltage detection module, and the node selection module are connected to a ground different from the ground to which the rectifier bridge BR is connected.

[0033] In this embodiment, in certain application scenarios, the ground of the high-voltage isolation module, the voltage detection module, the first node detection module, the second node detection module, and the node selection module is not the ground of the rectifier bridge BR. For high-voltage detection, since the ground of the rectifier bridge BR and the reference ground of the detection system are at different potentials, the input high-voltage signal can be changed from a positive high-voltage electrical signal to a negative high-voltage electrical signal. In this application scenario, the high-voltage detection module determines the timing relationship between the two AC input voltage signals based on the negative high-voltage signal.

[0034] The present invention also provides a power grid voltage detection system, comprising a plurality of power grid voltage detection circuits as described above connected in parallel to the power grid.

[0035] The present invention also provides a power grid voltage detection chip, which internally encapsulates the power grid voltage detection circuit as described above.

[0036] The above embodiments should not limit the present invention in any way, and any technical solutions obtained by equivalent replacement or equivalent conversion shall fall within the protection scope of the present invention.

Claims

1. A grid voltage detection circuit, characterized in that: include: High voltage isolation module, first node detection module, second node detection module, voltage detection module, node selection module; The first input end of the high-voltage isolation module is used to be electrically connected to the live wire of the power grid connected to the control switch, the second input end thereof is used to be electrically connected to the neutral wire of the power grid, the first output end thereof is electrically connected to the detection end of the first node detection module and the first detection end of the voltage detection module respectively, and the second output end thereof is electrically connected to the detection end of the second node detection module and the second detection end of the voltage detection module respectively; The enable terminal of the first node detection module is electrically connected to the first output terminal of the node selection module; The enable terminal of the second node detection module is electrically connected to the second output terminal of the node selection module; The output end of the voltage detection module is electrically connected to the input end of the node selection module; Wherein, when there is alternating current in the power grid, the voltage detection module detects the power-on state of the live wire and the neutral wire of the power grid through the voltage signal output by the high-voltage isolation module, and the power-on state represents the timing relationship of the voltage input signals on the live wire and the neutral wire of the power grid when the control switch is switched; The voltage detection module sends an enable signal to the first node detection module and the second node detection module respectively through the node selection module according to the timing relationship, so as to select an enabled object in the first node detection module and the second node detection module; The enabling object is used to detect the impedance of the power grid to determine the on-off state of the control switch.

2. The grid voltage detection circuit according to claim 1, characterized in that: The high-voltage isolation module includes a first high-voltage isolation unit and a second high-voltage isolation unit; The input end and the output end of the first high-voltage isolation unit serve as the first input end and the first output end of the high-voltage isolation module respectively; The input end and the output end of the second high-voltage isolation unit serve as the second input end and the second output end of the high-voltage isolation module respectively.

3. The grid voltage detection circuit according to claim 1, characterized in that: The node selection module sends opposite enable signals to the first node detection module and the second node detection module respectively.

4. The grid voltage detection circuit according to claim 1, characterized in that: The timing relationship is the order in which high levels appear in the voltage input signal on the live line of the power grid and the voltage input signal on the neutral line of the power grid when the state of the control switch is switched from off to on.

5. The grid voltage detection circuit according to claim 1, characterized in that: The timing relationship is the order in which the high levels of the voltage input signal on the live line of the power grid and the voltage input signal on the neutral line of the power grid disappear when the state of the control switch is switched from closed to cut off.

6. The grid voltage detection circuit according to claim 1, characterized in that: The node selection module is implemented based on an inverter.

7. The grid voltage detection circuit according to claim 1, characterized in that: It also includes a rectifier bridge; The two AC input terminals of the rectifier bridge are respectively used to electrically connect the live wire of the power grid and the neutral wire of the power grid, the positive output terminal thereof serves as a power bus interface, and the negative output terminal thereof is grounded; The power bus interface is connected with a capacitor.

8. The grid voltage detection circuit according to claim 7, characterized in that: The ground to which the high-voltage isolation module, the first node detection module, the second node detection module, the voltage detection module, and the node selection module are connected is different from the ground to which the rectifier bridge is connected.

9. A power grid voltage detection system, characterized in that: The invention comprises a plurality of grid voltage detection circuits as claimed in any one of claims 1 to 5 which are connected in parallel to a grid.

10. A power grid voltage detection chip, characterized in that: The grid voltage detection circuit as claimed in any one of claims 1 to 5 is encapsulated therein.

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