AC voltage detection circuit, detection method and detection device

Abstract

The present invention discloses an AC voltage detection circuit, comprising: a signal acquisition module, a signal conversion module, an isolation module and a decoding module; wherein the signal acquisition module is used to obtain the rectified DC bus voltage; the signal conversion module is used to acquire the DC bus voltage, convert the DC bus voltage into a pulse signal, and send the pulse signal to the isolation module; the isolation module is used to send the pulse signal to the decoding module through a coupled transmission mode; the decoding module is used to determine the AC voltage value according to the pulse signal. The present invention also discloses a method and device for detecting voltage by an AC voltage detection circuit.

Description

Technical Field

[0001] The present invention relates to voltage detection technology, and in particular to an AC voltage detection circuit, a detection method and a detection device. Background Art

[0002] At present, when detecting AC voltage, it is necessary to isolate and detect the AC voltage, but most of the isolation detection technologies on the market are based on voltage transformers or transformers. With the continuous increase in the price of copper materials in transformers, the cost of isolation detection is getting higher and higher; and when there are fluctuations or glitches in the power grid, it is easy to cause misjudgment of the signal at the secondary side, resulting in the detection accuracy of the AC voltage being affected by the load. Summary of the invention

[0003] In view of this, embodiments of the present invention are intended to provide an AC voltage detection circuit, a detection method, and a detection device.

[0004] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0005] The embodiment of the present invention further provides an AC voltage detection circuit, which includes: a signal acquisition module, a signal conversion module, an isolation module and a decoding module; wherein:

[0006] The signal acquisition module is used to obtain the rectified DC bus voltage;

[0007] The signal conversion module is used to collect the DC bus voltage, convert the DC bus voltage into a pulse signal, and send the pulse signal to the isolation module;

[0008] The isolation module is used to send the pulse signal to the decoding module through a coupled transmission mode;

[0009] The decoding module is used to determine the AC voltage value according to the pulse signal.

[0010] In the above solution, the circuit further includes a rectifier module, which is used to rectify the alternating current output by the transformer into direct current, and send the direct current to the signal acquisition module;

[0011] The signal acquisition module is used to generate the DC bus voltage according to the DC power.

[0012] In the above solution, the signal conversion module is used to convert the DC bus voltage into a pulse width modulation (PWM) duty cycle signal or a square wave signal;

[0013] The decoding module is specifically used to convert the PWM duty cycle signal or square wave signal into an AC voltage value according to a decoding algorithm.

[0014] In the above solution, the signal acquisition module includes: at least two resistors connected in series;

[0015] The at least two resistors connected in series are used to generate a DC bus voltage corresponding to a connection point between any two resistors in the at least two resistors connected in series according to the DC power.

[0016] In the above solution, the isolation module includes: an optical coupler;

[0017] The optical coupler is used to send the pulse signal to the decoding module through a coupled transmission mode.

[0018] The embodiment of the present invention further provides a method for detecting voltage using an AC voltage detection circuit, wherein the AC voltage detection circuit comprises: a signal acquisition module, a signal conversion module, an isolation module and a decoding module; the method comprises:

[0019] The signal acquisition module obtains the rectified DC bus voltage;

[0020] The signal conversion module collects the DC bus voltage, converts the DC bus voltage into a pulse signal, and sends the pulse signal to the isolation module;

[0021] The isolation module sends the pulse signal to the decoding module through a coupled transmission mode;

[0022] The decoding module determines an AC voltage value according to the pulse signal.

[0023] In the above solution, the circuit further includes a rectifier module;

[0024] Before the signal acquisition module obtains the rectified DC bus voltage, the method further includes:

[0025] The rectifier module rectifies the alternating current output by the transformer into direct current, and sends the direct current to the signal acquisition module;

[0026] The signal acquisition module obtains the rectified DC bus voltage, including:

[0027] The signal acquisition module generates the DC bus voltage according to the DC power.

[0028] In the above solution, the step of converting the DC bus voltage into a pulse signal includes:

[0029] The signal conversion module converts the DC bus voltage into a PWM duty cycle signal or a square wave signal;

[0030] The decoding module determines the AC voltage value according to the pulse signal, including:

[0031] The decoding module converts the PWM duty cycle signal or the square wave signal into an AC voltage value according to a decoding algorithm.

[0032] In the above solution, the signal acquisition module includes: at least two resistors connected in series;

[0033] The signal acquisition module obtains the rectified DC bus voltage, including:

[0034] The at least two resistors connected in series generate a DC bus voltage corresponding to a connection point of any two resistors among the at least two resistors connected in series according to the DC power.

[0035] In the above solution, the isolation module includes: an optical coupler;

[0036] The isolation module sends the pulse signal to the decoding module through a coupled transmission mode, including:

[0037] The optical coupler sends the pulse signal to the decoding module through a coupled transmission mode.

[0038] An embodiment of the present invention further provides an AC voltage detection device, the device comprising: any one of the AC voltage detection circuits described above.

[0039] An AC voltage detection circuit, detection method and detection device provided by an embodiment of the present invention include: a signal acquisition module, a signal conversion module, an isolation module and a decoding module; wherein the signal acquisition module is used to obtain the rectified DC bus voltage; the signal conversion module is used to acquire the DC bus voltage, convert the DC bus voltage into a pulse signal, and send the pulse signal to the isolation module; the isolation module is used to send the pulse signal to the decoding module through a coupled transmission mode; the decoding module is used to determine the AC voltage value according to the pulse signal. The circuit and method provided by an embodiment of the present invention can use a cheap chip to acquire the DC bus voltage, and convert the acquired DC bus voltage into a pulse signal (such as a PWM duty cycle signal or a square wave signal), determine the AC voltage value according to the pulse signal, and realize coupled transmission through a separate isolation module, thereby reducing the isolation cost while ensuring the detection accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 A schematic diagram of the structure of an AC voltage detection circuit provided by an embodiment of the present invention;

[0041] Figure 2A schematic diagram of the structure of another AC voltage detection circuit provided by an embodiment of the present invention;

[0042] Figure 3 A schematic diagram of a flow chart of an AC voltage detection method provided by an embodiment of the present invention;

[0043] Figure 4 A schematic flow chart of another AC voltage detection method provided by an embodiment of the present invention;

[0044] Figure 5 A schematic diagram of the structure of yet another AC voltage detection circuit provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0045] In an embodiment of the present invention, an AC voltage detection circuit includes: a signal acquisition module, a signal conversion module, an isolation module and a decoding module; wherein the signal acquisition module is used to obtain a rectified DC bus voltage; the signal conversion module is used to acquire the DC bus voltage, convert the DC bus voltage into a pulse signal, and send the pulse signal to the isolation module; the isolation module is used to send the pulse signal to the decoding module through a coupled transmission mode; and the decoding module is used to determine an AC voltage value according to the pulse signal.

[0046] The present invention will be further described in detail below in conjunction with the embodiments.

[0047] Figure 1 A schematic diagram of the structure of an AC voltage detection circuit provided by an embodiment of the present invention; Figure 1 As shown, the circuit includes: a signal acquisition module 101, a signal conversion module 102, an isolation module 103 and a decoding module 104; wherein,

[0048] The signal acquisition module 101 is used to obtain the rectified DC bus voltage;

[0049] Specifically, the circuit further includes a rectifier module 100, which is used to rectify the alternating current output by the transformer into direct current, and send the direct current to the signal acquisition module 101;

[0050] The rectifier module 100 may include: a full-wave rectifier bridge or a half-wave rectifier circuit;

[0051] The full-wave rectifier bridge or half-wave rectifier circuit is used to rectify the alternating current output by the transformer into direct current.

[0052] Specifically, the signal acquisition module 101 is used to generate the DC bus voltage according to the DC power.

[0053] Here, the signal acquisition module 101 may include: at least two resistors connected in series;

[0054] One end of the at least two resistors connected in series receives the rectified direct current, and the other end is grounded.

[0055] The at least two resistors connected in series are specifically used to generate a DC bus voltage from the connection point of any two resistors in the at least two resistors connected in series according to the DC power. Here, the connection point of any two resistors can be pre-set and recorded by the designer in the early stage of circuit design.

[0056] Specifically, it is assumed that the signal acquisition module includes: N resistors, N is greater than or equal to 2, that is, including: resistors R1, R2, ..., R N ; wherein the resistor R1 receives the DC power, the resistor R N Ground; the connection point is the resistor R i With resistor R i+1 Between, i is less than or equal to N and greater than or equal to 1;

[0057] The DC bus voltage

[0058] Wherein, V represents the voltage provided by the direct current, and the resistors R1, R2, ..., and R N The resistance values ​​of the resistor R i With resistor R i+1 The connection point between them is preset and recorded. The above formula (1) can express the proportional relationship between the DC bus voltage and the voltage provided by the DC power.

[0059] The signal conversion module 102 is used to collect the DC bus voltage, convert the DC bus voltage into a pulse signal, and send the pulse signal to the isolation module;

[0060] Specifically, the signal conversion module 102 is used to convert the DC bus voltage into a PWM duty cycle signal or a square wave signal.

[0061] Specifically, the signal conversion module can adopt a first processing chip; the first processing chip includes at least: a first pin and a second pin; wherein the first pin receives the DC bus voltage, and the first processing chip converts the DC bus voltage into a PWM duty cycle signal or a square wave signal, and sends the PWM duty cycle signal or the square wave signal to the isolation module through the second pin.

[0062] Here, the signal conversion module stores a conversion rule in advance, and the signal conversion module converts the DC bus voltage into a PWM duty cycle signal or a square wave signal according to the conversion rule.

[0063] The first pin may be provided with an analog-to-digital converter (AD converter), and the analog-to-digital converter is used to perform analog-to-digital conversion on the DC bus voltage, that is, to convert the analog signal of the DC bus voltage into a digital signal;

[0064] The signal conversion module is specifically used to perform analog-to-digital conversion on the DC bus voltage, determine the high and low changes of the DC bus voltage according to the digital signal of the DC bus voltage obtained after the analog-to-digital conversion; and determine the PWM duty cycle signal or square wave signal according to the high and low changes of the DC bus voltage.

[0065] Here, the signal conversion module may also include a preset filtering algorithm. Before performing analog-to-digital conversion, the signal conversion module may filter the DC bus voltage to ensure that the DC bus voltage is more accurate. The filtering algorithm may include: limiting filtering, median filtering, arithmetic mean filtering, Kalman filtering, etc.

[0066] The isolation module 103 is used to send the pulse signal to the decoding module through a coupled transmission mode;

[0067] Specifically, the isolation module 103 includes: an optical coupler;

[0068] The optical coupler is used to send the pulse signal to the decoding module through a coupled transmission mode.

[0069] The decoding module 104 is used to determine the AC voltage value according to the pulse signal.

[0070] Specifically, the decoding module 104 is specifically configured to convert the PWM duty cycle signal or the square wave signal into an AC voltage value according to a decoding algorithm.

[0071] Here, the decoding module is specifically used to convert the PWM duty cycle signal or square wave signal into an AC voltage value according to a decoding algorithm.

[0072] Here, the decoding module may use a second processing chip, and the second processing chip pre-stores a decoding algorithm;

[0073] Specifically, the decoding module is specifically used to determine the DC bus voltage according to the PWM duty cycle signal or the square wave signal; determine the voltage provided by the DC power according to the DC bus voltage and the resistance values ​​of the at least two resistors connected in series, and determine the AC voltage value according to the voltage provided by the DC power. Here, the change of the AC voltage value corresponds to the high and low changes of the DC bus voltage, that is, the decoding module can determine the change of the AC voltage according to the high and low changes of the DC bus voltage.

[0074] It should be noted that the decoding module may store the resistance values ​​of the at least two resistors connected in series, and the voltage provided by the DC power may be determined in combination with the above formula (1); the decoding module may also store the information of the transformer (such as the number of turns of the transformer), so that the processor may determine the AC voltage value based on the voltage provided by the DC power and the information of the transformer.

[0075] Specifically, the circuit may further include: a resistor-capacitor absorption module, and the resistor-capacitor absorption module may include: at least one capacitor; when the circuit is running, there is noise in the DC bus voltage, and the at least one capacitor can be used to filter out the noise in the DC bus voltage.

[0076] Figure 2 A schematic diagram of the structure of another AC voltage detection circuit provided by an embodiment of the present invention; Figure 2 As shown, the circuit includes: a rectifier module, a signal acquisition module, a signal conversion module, an isolation module and a decoding module; wherein,

[0077] The rectifier module includes: a full-wave rectifier bridge; the full-wave rectifier bridge is used to rectify the alternating current output by the transformer into direct current; Figure 2 As shown, the full-wave rectifier bridge rectifies the AC power output by the first transformer into DC power (HV).

[0078] The signal acquisition module is used to receive the direct current and generate a direct current bus voltage according to the direct current;

[0079] In this embodiment, the signal acquisition module includes: a first resistor R1, a second resistor R2, and a third resistor R3; the first resistor R1, the second resistor R2 and the third resistor R3 are connected in series in sequence; the first resistor R1 receives the direct current (HV), and the third resistor R3 is grounded (PGND); here, the connection point between the second resistor R2 and the third resistor R3 can be used as a signal point for collecting the DC bus voltage; of course, in other implementations, the connection point between the first resistor R1 and the second resistor R2 can also be used as a signal point for collecting the DC bus voltage.

[0080]

[0081] Wherein, VO represents the voltage of the connection point, that is, the DC bus voltage; V represents the voltage provided by the DC power; and the resistor R1, the resistor R2 and the resistor R3 represent the resistance values ​​of the first resistor, the second resistor and the third resistor respectively.

[0082] The signal conversion module is used to determine the DC bus voltage, convert the DC bus voltage into a PWM duty cycle signal or a square wave signal, and send the PWM duty cycle signal or the square wave signal to the isolation module;

[0083] In this embodiment, the signal conversion module adopts a first processing chip; the first processing chip at least includes: a first pin and a second pin; the first pin is provided with an analog-to-digital converter, the first pin (AD_PIN) receives the DC bus voltage, and converts the analog signal of the DC bus voltage into a digital signal; the first processing chip determines the PWM duty cycle signal or pulse signal according to the digital signal of the DC bus voltage after the analog-to-digital conversion, and sends the PWM duty cycle signal or square wave signal to the isolation module through the second pin (which is a PWM port or an ordinary IO port).

[0084] The isolation module is used to send the PWM duty cycle signal or the square wave signal to the decoding module through a coupled transmission mode;

[0085] In this embodiment, the isolation module includes: an optical coupler; the optical coupler includes: a light emitting diode and a phototransistor; one end of the light emitting diode is connected to the power supply voltage of the circuit (generally +5V), and the other end is connected to the signal conversion module; one end of the phototransistor is connected to the power supply voltage of the circuit and connected to the decoding module, and the other end is grounded (PGND). Here, the signal conversion module and the decoding module are isolated by the optical coupler composed of the light emitting diode and the phototransistor, so that the signal conversion module and the decoding module have no direct electrical connection, thereby preventing interference caused by electrical connection, thereby achieving isolation.

[0086] In this embodiment, the isolation module may further include: a voltage follower (also called an operational amplifier). When the isolation module includes the voltage follower, the voltage follower is connected between the light emitting diode and the signal conversion module.

[0087] The decoding module is used to convert the PWM duty cycle signal or square wave signal into an AC voltage value according to a decoding algorithm.

[0088] In practical applications, the signal conversion module and the decoding module can be implemented by a central processing unit (CPU), a digital signal processor (DSP), a microcontroller unit (MCU) or a field-programmable gate array (FPGA).

[0089] Figure 3 A flow chart of an AC voltage detection method provided by an embodiment of the present invention; Figure 3 As shown, the method can be applied to Figure 1 The AC voltage detection circuit shown in the figure includes: a signal acquisition module, a signal conversion module, an isolation module and a decoding module; the method includes:

[0090] Step 301: The signal acquisition module obtains the rectified DC bus voltage;

[0091] Specifically, the circuit also includes a rectifier module;

[0092] Before step 301, the method further includes: the rectifying module rectifying the alternating current output by the transformer into direct current, and sending the direct current to the signal acquisition module.

[0093] Specifically, the signal acquisition module includes: at least two resistors connected in series;

[0094] The signal acquisition module obtains the rectified DC bus voltage, including:

[0095] The at least two resistors connected in series generate a DC bus voltage corresponding to a connection point of any two resistors among the at least two resistors connected in series according to the DC power.

[0096] Step 302: The signal conversion module collects the DC bus voltage, converts the DC bus voltage into a pulse signal, and sends the pulse signal to the isolation module;

[0097] Specifically, converting the DC bus voltage into a pulse signal includes:

[0098] The signal conversion module converts the DC bus voltage into a PWM duty cycle signal or a square wave signal.

[0099] Step 303: The isolation module sends the pulse signal to the decoding module through a coupled transmission mode;

[0100] Specifically, the isolation module includes: an optical coupler;

[0101] The isolation module sends the pulse signal to the decoding module through a coupled transmission mode, including:

[0102] The optical coupler sends the pulse signal to the decoding module through a coupled transmission mode.

[0103] Step 304: The decoding module determines an AC voltage value according to the pulse signal.

[0104] Specifically, the step 304 includes:

[0105] The decoding module converts the PWM duty cycle signal or the square wave signal into an AC voltage value according to a decoding algorithm.

[0106] Figure 4 A flow chart of another AC voltage detection method provided by an embodiment of the present invention; Figure 4 As shown, the method comprises:

[0107] Step 401, the rectifier bridge rectifies the AC power output by the transformer into DC power;

[0108] Here, the rectifier bridge may be a full-wave rectifier bridge or a half-wave rectifier circuit.

[0109] Step 402: The signal acquisition module receives the DC power and generates a DC bus voltage according to the DC power.

[0110] Specifically, the signal acquisition module includes: at least two resistors connected in series;

[0111] Generating a DC bus voltage according to the DC power includes:

[0112] The at least two resistors connected in series generate a DC bus voltage corresponding to a connection point of any two resistors among the at least two resistors connected in series according to the DC power.

[0113] Step 403: The signal conversion module converts the DC bus voltage into a PWM duty cycle signal;

[0114] Step 404: The optical coupler sends the PWM duty cycle signal to the decoding module through a coupling transmission mode;

[0115] Step 405: The decoding module determines the AC voltage value according to the PWM duty cycle signal.

[0116] Figure 5 A schematic diagram of the structure of another AC voltage detection circuit provided by an embodiment of the present invention; Figure 5As shown, the circuit at least includes: a 220W power supply AC, a transformer U1, a rectifier bridge BD1, a signal acquisition module CL1, a signal conversion chip MCU1, an optical coupler OC, and a decoding chip MCU2; wherein,

[0117] The rectifier bridge BD1 rectifies the AC power output by the transformer U1 into DC power; here, the rectifier bridge is a full-wave rectifier bridge; the signal acquisition module CL1 receives the DC power, and generates a DC bus voltage according to the DC power; the signal conversion chip MCU1 acquires the DC bus voltage, converts the DC bus voltage into a PWM duty cycle signal or a square wave signal, and sends the PWM duty cycle signal or square wave signal to the optocoupler OC; the optocoupler OC sends the PWM duty cycle signal or square wave signal to the decoding chip MCU2 through a coupling transmission mode; the decoding chip MCU2 determines the AC voltage value according to the PWM duty cycle signal or square wave signal.

[0118] In this embodiment, the signal acquisition module CL1 includes: three resistors connected in series, namely, a resistor R90, a resistor R91, and a resistor R92;

[0119] Generating a DC bus voltage according to the DC power includes:

[0120] The resistor R90 , the resistor R91 , and the resistor R92 generate a DC bus voltage corresponding to a connection point between the resistor R91 and the resistor R92 according to the DC power.

[0121] The embodiment of the present invention further provides an AC voltage detection device, the device comprising: an AC voltage detection circuit; the circuit comprising: a signal acquisition module, a signal conversion module, an isolation module and a decoding module; wherein,

[0122] The signal acquisition module is used to obtain the rectified DC bus voltage;

[0123] The signal conversion module is used to collect the DC bus voltage, convert the DC bus voltage into a pulse signal, and send the pulse signal to the isolation module;

[0124] The isolation module is used to send the pulse signal to the decoding module through a coupled transmission mode;

[0125] The decoding module is used to determine the AC voltage value according to the pulse signal.

[0126] Specifically, the device may further include a rectifying module, which is used to rectify the alternating current output by the transformer into direct current, and send the direct current to the signal acquisition module;

[0127] The signal acquisition module is used to generate the DC bus voltage according to the DC power.

[0128] Specifically, the signal conversion module is used to convert the DC bus voltage into a PWM duty cycle signal or a square wave signal;

[0129] The decoding module is specifically used to convert the PWM duty cycle signal or square wave signal into an AC voltage value according to a decoding algorithm.

[0130] Specifically, the signal acquisition module includes: at least two resistors connected in series;

[0131] The at least two resistors connected in series are used to generate a DC bus voltage corresponding to a connection point between any two resistors in the at least two resistors connected in series according to the DC power.

[0132] Specifically, the isolation module includes: an optical coupler;

[0133] The optical coupler is used to send the pulse signal to the decoding module through a coupled transmission mode.

[0134] The signal conversion module and the decoding module mentioned above can be implemented by CPU, DSP, MCU or FPGA.

[0135] The above description is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An AC voltage detection circuit, characterized in that: The circuit includes: a signal acquisition module, a signal conversion module, an isolation module and a decoding module; wherein, The signal acquisition module is used to obtain the rectified DC bus voltage; The signal conversion module is used to collect the DC bus voltage, convert the DC bus voltage into a pulse signal, and send the pulse signal to the isolation module; The isolation module is used to send the pulse signal to the decoding module through a coupled transmission mode; The decoding module is used to determine the AC voltage value according to the pulse signal; The signal conversion module adopts a first processing chip, and is specifically used to determine a pulse width modulation (PWM) duty cycle signal or a square wave signal according to the high and low changes of the DC bus voltage; The decoding module is specifically used to convert the PWM duty cycle signal or square wave signal into an AC voltage value according to a decoding algorithm; The circuit also includes a rectifier module, which is used to rectify the alternating current output by the transformer into direct current, and send the direct current to the signal acquisition module; The signal acquisition module comprises: at least two resistors connected in series; The at least two resistors connected in series are used to generate a DC bus voltage corresponding to a connection point between any two resistors in the at least two resistors connected in series according to the DC power; The decoding module is specifically used to determine the DC bus voltage according to the PWM duty cycle signal or the square wave signal; Determining a voltage provided by the direct current according to the direct current bus voltage and the resistance values ​​of the at least two resistors connected in series; An AC voltage value is determined according to the voltage provided by the DC power, and a change in the AC voltage value corresponds to a high or low change in the DC bus voltage.

2. The circuit according to claim 1, characterized in that The isolation module comprises: an optical coupler; The optical coupler is used to send the pulse signal to the decoding module through a coupled transmission mode.

3. A method for detecting voltage using an AC voltage detection circuit, characterized in that: The AC voltage detection circuit includes: a signal acquisition module, a signal conversion module, an isolation module and a decoding module; the method includes: The signal acquisition module obtains the rectified DC bus voltage; The signal conversion module collects the DC bus voltage, converts the DC bus voltage into a pulse signal, and sends the pulse signal to the isolation module; The isolation module sends the pulse signal to the decoding module through a coupled transmission mode; The decoding module determines the AC voltage value according to the pulse signal; The step of converting the DC bus voltage into a pulse signal comprises: The signal conversion module determines the PWM duty cycle signal or the square wave signal according to the high and low changes of the DC bus voltage; the signal conversion module adopts a first processing chip; The decoding module determines the AC voltage value according to the pulse signal, including: The decoding module converts the PWM duty cycle signal or square wave signal into an AC voltage value according to a decoding algorithm; The circuit also includes a rectifier module; Before the signal acquisition module obtains the rectified DC bus voltage, the method further includes: The rectifier module rectifies the alternating current output by the transformer into direct current, and sends the direct current to the signal acquisition module; The signal acquisition module comprises: at least two resistors connected in series; The signal acquisition module obtains the rectified DC bus voltage, including: The at least two resistors connected in series generate a DC bus voltage corresponding to a connection point of any two resistors in the at least two resistors connected in series according to the DC power; The decoding module is specifically used to determine the DC bus voltage according to the PWM duty cycle signal or the square wave signal; Determining a voltage provided by the direct current according to the direct current bus voltage and the resistance values ​​of the at least two resistors connected in series; An AC voltage value is determined according to the voltage provided by the DC power, and a change in the AC voltage value corresponds to a high or low change in the DC bus voltage.

4. The method according to claim 3, characterized in that The isolation module comprises: an optical coupler; The isolation module sends the pulse signal to the decoding module through a coupled transmission mode, including: The optical coupler sends the pulse signal to the decoding module through a coupled transmission mode.

5. An AC voltage detection device, characterized in that: The device comprises: the AC voltage detection circuit as described in any one of claims 1 to 2.

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