Alternating current acquisition circuit, monitoring device and electric equipment

Abstract

The application relates to an alternating current collection circuit. The alternating current collection circuit comprises a square wave generation circuit, a logic circuit and a comparison circuit. The first end of the square wave generation circuit is connected to an alternating current, the second end of the square wave generation circuit is connected to the first end of the logic circuit, the second end of the logic circuit is connected to the first end of the comparison circuit, the second end of the comparison circuit is connected to an alternating current, the third end of the comparison circuit is connected to the third end of the logic circuit, the second end of the logic circuit is connected to a signal output end, and the comparison circuit can adjust the duty cycle of the signal output by the signal output end. The alternating current collection circuit can transmit a voltage signal through the duty cycle, transmit a frequency signal through a frequency period, the frequency of the signal output by the signal output end matches the frequency of the signal connected to the square wave generation circuit, and thus the signal output by the output end can simultaneously realize voltage and frequency collection of the connected signal, simultaneously transmit multiple signal states through a single port, and improve the utilization rate of the output port.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, and in particular to an AC power acquisition circuit, a monitoring device, and an electrical appliance. Background Technology

[0002] With the development of science and technology, various power control devices have emerged. For example, a frequency converter is a power control device that controls an AC motor by changing the frequency of the power supply. It relies on the switching of transistors to adjust the voltage and frequency of the output power supply, providing the required power voltage according to the actual needs of the motor, thereby achieving energy saving and speed regulation. Frequency converters need to sample the AC power supply to provide over / under voltage protection and over / under frequency protection.

[0003] Traditional frequency converters have multiple modules such as rectifier modules and inverter modules. In order to sample the AC power, it is necessary to sample different parameters of the AC power through multiple ports, which leads to the continuous expansion of the number of ports and unsaturated port utilization. The traditional sampling port has low functional density. Summary of the Invention

[0004] This invention addresses the problem of low functional density of traditional sampling ports by proposing an AC power acquisition circuit, monitoring device, and power supply equipment, which can achieve the technical effect of improving port utilization.

[0005] An AC power acquisition circuit includes a square wave generating circuit, a logic circuit, and a comparison circuit. The first terminal of the square wave generating circuit is connected to AC power, the second terminal of the square wave generating circuit is connected to the first terminal of the logic circuit, the second terminal of the logic circuit is connected to the first terminal of the comparison circuit, the second terminal of the comparison circuit is connected to AC power, the third terminal of the comparison circuit is connected to the third terminal of the logic circuit, and the second terminal of the logic circuit is connected to a signal output terminal.

[0006] The square wave generating circuit is used to convert the incoming AC power into a square wave signal and transmit it to the logic circuit. The logic circuit switches between on and off states according to the high and low levels of the square wave signal. The comparison circuit is used to feed back the comparison result between the output signal of the logic circuit and the AC power to the logic circuit, and adjust the duty cycle of the output signal at the signal output terminal so that the frequency of the output signal at the signal output terminal matches the frequency of the signal input to the square wave generating circuit.

[0007] An AC power monitoring device includes a main control chip and an AC power acquisition circuit as described above, wherein the main control chip is connected to the signal output terminal of the AC power acquisition circuit.

[0008] An electrical appliance includes an AC power monitoring device as described above.

[0009] The aforementioned AC power acquisition circuit, monitoring device, and electrical equipment include a square wave generating circuit, a logic circuit, and a comparator circuit. The first terminal of the square wave generating circuit is connected to AC power. The second terminal of the square wave generating circuit is connected to the first terminal of the logic circuit. The second terminal of the logic circuit is connected to the first terminal of the comparator circuit. The second terminal of the comparator circuit is connected to AC power. The third terminal of the comparator circuit is connected to the third terminal of the logic circuit. The second terminal of the logic circuit is connected to the signal output terminal. The square wave generating circuit converts the input AC power into a square wave signal and transmits it to the logic circuit. The logic circuit switches between on and off states based on the high and low levels of the square wave signal. The comparator circuit converts the output signal of the logic circuit into a signal output terminal. The comparison result between the signal and the AC current is fed back to the logic circuit to adjust the duty cycle of the output signal. This ensures that the frequency of the output signal matches the frequency of the signal input to the square wave generation circuit. The comparison circuit can adjust the duty cycle of the output signal, allowing the AC current acquisition circuit to transmit voltage signals via duty cycle and frequency signals via frequency period. The frequency of the output signal matches the frequency of the signal input to the square wave generation circuit, enabling the output signal to simultaneously acquire both the voltage and frequency of the input signal. This allows for the simultaneous transmission of multiple signal states through a single port, improving the utilization rate of the output port.

[0010] In one embodiment, the square wave generating circuit includes a first comparator, a first resistor, a second resistor, and a third resistor. One end of the first resistor is connected to AC power, and the other end is connected to the non-inverting input of the first comparator. The inverting input of the first comparator is grounded through the second resistor, and the output of the first comparator is connected to the first terminal of the logic circuit.

[0011] In one embodiment, the logic circuit includes a first switch, a second switch, and a third switch. The control terminal of the first switch is connected to the second terminal of the square wave generating circuit. The first terminal of the first switch is connected to the control terminal of the second switch and is connected to a reference voltage. The first terminal of the second switch is connected to the first terminal of the comparator circuit. The second terminal of the second switch is connected to the first terminal of the third switch. The control terminal of the third switch is connected to the third terminal of the comparator circuit. The second terminals of the third switch and the first switch are both grounded.

[0012] In one embodiment, the logic circuit further includes a diode, with a first terminal of the second switch connected to the anode of the diode and the cathode of the diode connected to a first terminal of the comparator circuit.

[0013] In one embodiment, the logic circuit further includes a fourth resistor and a sixth resistor, wherein the first terminal of the first switch is connected to a reference voltage through the sixth resistor, and the first terminal of the second switch is connected to a reference voltage through the fourth resistor.

[0014] In one embodiment, the comparison circuit includes a second comparator and a seventh resistor. The second terminal of the logic circuit is connected to the inverting terminal of the second comparator, the inverting terminal of the second comparator is grounded, the non-inverting terminal of the second comparator is connected to AC power, and the output terminal of the second comparator is connected to the third terminal of the logic circuit through the seventh resistor.

[0015] In one embodiment, the comparator circuit further includes a fifth resistor and a second capacitor, one end of the second capacitor being connected to the second terminal of the logic circuit and the other end being grounded, and one end of the fifth resistor being connected to the inverting terminal of the second comparator and the other end being grounded.

[0016] In one embodiment, the AC power acquisition circuit further includes a main control chip receiving circuit, and the logic circuit is connected to the signal output terminal through the main control chip receiving circuit.

[0017] In one embodiment, the main control chip receiving circuit includes a second diode, a third diode, and a resistor. The anode of the second diode is used to receive voltage, the cathode of the third diode is grounded, and the common terminal of the cathode of the second diode and the anode of the third diode is connected to the signal output terminal. One end of the resistor is connected to the second terminal of the logic circuit, and the other end is connected to the signal output terminal. Attached Figure Description

[0018] Figure 1 This is a block diagram of an AC power acquisition circuit in one embodiment;

[0019] Figure 2 This is a structural diagram of an AC power acquisition circuit in one embodiment;

[0020] Figure 3 This is a flowchart of the AC power acquisition circuit in one embodiment. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described more comprehensively below through embodiments and in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0022] In one embodiment, see Figure 1 and Figure 2An AC power acquisition circuit is provided, including a square wave generating circuit 100, a logic circuit 200, and a comparison circuit 300. The first terminal of the square wave generating circuit 100 is connected to AC power, the second terminal of the square wave generating circuit 100 is connected to the first terminal of the logic circuit 200, the second terminal of the logic circuit 200 is connected to the first terminal of the comparison circuit 300, the second terminal of the comparison circuit 300 is connected to AC power, the third terminal of the comparison circuit 300 is connected to the third terminal of the logic circuit 200, and the second terminal of the logic circuit 200 is connected to a signal output terminal.

[0023] The square wave generating circuit 100 converts the input AC power into a square wave signal, which is then transmitted to the logic circuit 200. The logic circuit 200 switches between on and off states based on the high and low levels of the square wave signal. The comparison circuit 300 feeds back the comparison result between the output signal of the logic circuit 200 and the AC power to the logic circuit 200, adjusting the duty cycle of the output signal to match the frequency of the signal input to the square wave generating circuit 100. This allows the output signal to simultaneously acquire both the voltage and frequency of the input signal, enabling the simultaneous transmission of multiple signal states through a single port and improving the utilization rate of the output port. The frequency converter requires over / under voltage protection and over / under frequency protection for the AC voltage, triggering protection when the input AC voltage is over / under voltage or under / under frequency to prevent damage to the frequency converter. AC power acquisition circuits can be applied to frequency converters such as photovoltaic frequency converters. They can transmit voltage amplitude signals and frequency signals simultaneously through a single input port. When there are few original I / O (Input / Output) ports, both over-voltage and under-frequency signals can be detected quickly through the same port, realizing full utilization of input and output ports and reducing chip development costs.

[0024] Specifically, the first terminal of the square wave generation circuit 100 serves as the input terminal of the entire AC power acquisition circuit, used to connect AC power. After the AC power is transmitted to the AC power acquisition circuit, it is processed by the AC power acquisition circuit, and the signal output terminal of the AC power acquisition circuit can reflect the characteristic parameters of the connected AC quantity, thus completing the acquisition of the characteristic parameters of the connected AC power. The AC power is usually an AC voltage sampling signal, which is a sine wave signal. The square wave generation circuit 100 can convert the connected sine wave signal into a square wave signal, and the frequency period of the square wave signal is equal to the frequency period of the sine wave signal. After the square wave signal is transmitted to the logic circuit 200, the logic circuit 200 adjusts the logic to affect the output. Depending on the high or low level of the square wave signal, the logic circuit 200 will be in a conducting or turning-off state. The comparison circuit 300 feeds back the comparison result between the output signal of the logic circuit 200 and the AC power to the logic circuit to adjust the duty cycle of the output signal, thereby generating the required frequency-tracking duty cycle adjustable signal, i.e., the desired signal. The frequency of the output signal at the signal output terminal matches the frequency of the signal input to the square wave generation circuit 100, generally being equal or within the allowable error range. The duty cycle of the output signal at the signal output terminal is related to the voltage amplitude of the input AC power. At the same frequency, different voltage amplitudes result in different percentages of the input AC power reaching a certain fixed voltage. Therefore, the relationship between the voltage amplitude of the input AC power and the duty cycle of the output signal at the signal output terminal can be obtained. Thus, by analyzing the duty cycle of the output signal at the signal output terminal, the voltage amplitude of the input AC power can be determined.

[0025] The structure of the square wave generating circuit 100 is not unique; it only needs to convert the input AC power into a square wave signal. For example, the square wave generating circuit 100 may include a comparator with a fixed connection at one input terminal. When the voltage value of the input AC power is greater than 0, the comparator outputs a high level; when the voltage value of the input AC power is less than 0, the comparator outputs a low level. Taking the AC power as a sine wave signal as an example, the comparator can convert the sine wave into a square wave signal with only high and low levels before outputting it. The structure of the logic circuit 200 is also not unique; for example, it may include a switching transistor. The switching transistor receives different voltages and will be in the on or off state at different times, thereby realizing the logic output. The structure of the comparator circuit 300 is not unique. For example, the comparator circuit 300 can also include a comparator. One input terminal of the comparator is connected to AC power, and the other input terminal is connected to the output terminal of the logic circuit 200. Different types of voltage levels are connected according to the on or off state of the logic circuit 200. The different types of voltage levels are compared with the AC power, so the comparator can output a high or low level. The frequency and period of the signal output by the comparator are equal to those of the AC power. The duty cycle can also reflect the voltage amplitude of the AC power. Thus, the signal output terminal of the AC power acquisition circuit can acquire both the voltage and frequency of the AC power, improving the port utilization.

[0026] In one embodiment, see Figure 2 The square wave generating circuit 100 includes a first comparator L1, a first resistor R1, a second resistor R2, and a third resistor R3. One end of the first resistor R1 serves as the first terminal of the square wave generating circuit 100, connected to AC power, and the other end is connected to the non-inverting input of the first comparator L1. The inverting input of the first comparator L1 is grounded through the second resistor R2. The output terminal of the first comparator L1 serves as the second terminal of the square wave generating circuit 100, connected to the first terminal of the logic circuit 200. Specifically, the inverting input of the first comparator L1 is grounded through the second resistor R2. After the AC power passes through the first resistor R1, it reaches the non-inverting input of the first comparator L1. When the AC voltage is greater than 0, the AC power is in the positive half-cycle, and the output terminal of the first comparator L1 outputs Uout1 at a high level. When the AC voltage is less than 0, the AC power is in the negative half-cycle, and the output terminal of the first comparator L1 outputs Uout1 at a low level. Thus, the first comparator L1 can convert the input AC power into a square wave signal with only high and low levels for output. The resistance values ​​of the first resistor R1, the second resistor R2, and the third resistor R3 can be selected according to actual needs, as long as those skilled in the art deem it feasible.

[0027] In one embodiment, see Figure 2The logic circuit 200 includes a first switch G1, a second switch G2, and a third switch G3. The control terminal of the first switch G1 serves as the first terminal of the logic circuit 200 and is connected to the second terminal of the square wave generating circuit 100. The first terminal of the first switch G1 is connected to the control terminal of the second switch G2 and is connected to a reference voltage. The first terminal of the second switch G2 serves as the second terminal of the logic circuit 200 and is connected to the first terminal of the comparator circuit 300. The second terminal of the second switch G2 is connected to the first terminal of the third switch G3. The control terminal of the third switch G3 serves as the third terminal of the logic circuit 200 and is connected to the third terminal of the comparator circuit 300. The second terminals of the third switch G3 and the second terminals of the first switch G1 are both grounded.

[0028] Specifically, the control transistor of the first switch G1 is connected to the second terminal of the square wave generating circuit 100. Different high and low levels of the square wave signal result in different switching states of the first switch G1. The first terminal of the first switch G1 is connected to the control terminal of the second switch G2, and the second terminal of the first switch G1 is grounded. Different switching states of the first switch G1 result in different switching states of the second switch G2. The second terminal of the second switch G2 is connected to the first terminal of the third switch G3. The control terminal of the third switch G3 is connected to the third terminal of the comparator circuit 300, and the second terminal of the third switch G3 is grounded. The third switch G3 switches between on and off states based on the high and low levels of the output signal from the comparator circuit 300. Therefore, when the second switch G2 is in the on or off state, different high and low levels of the signal received by the comparator circuit 300 result in different high and low levels of the output signal, and consequently, different on and off states of the third switch G3. Taking the square wave generating circuit 100, which includes a first comparator L1, a first resistor R1, a second resistor R2, and a third resistor R3, as an example, when the output Uout1 of the first comparator L1 is high, the first switch G1 is off, causing the second switch G2 to turn on. When the comparator circuit output is high, the third switch G3 turns on. When the input AC current enters the negative half-cycle, the output Uout1 of the first comparator L1 is low, causing the first switch G1 to turn on and the second switch G2 to turn off. When the comparator circuit output is low, the third switch G3 turns off, thus achieving the alternation of positive and negative cycles. The period of the output signal of the logic circuit 200 is consistent with the period of the AC current connected to the square wave generating circuit 100.

[0029] In one embodiment, see Figure 2The logic circuit 200 also includes a diode D1. The first terminal of the second switching transistor G2 is connected to the anode of diode D1, and the cathode of diode D1 is connected to the first terminal of the comparator circuit 300. Since the anode of diode D1 is connected to the first terminal of the second switching transistor G2, and the cathode of diode D1 is connected to the first terminal of the comparator circuit 300, current can only flow from the anode to the cathode of diode D1; the reverse direction will cut off the current. Therefore, diode D1 can stabilize the voltage input to the comparator circuit 300 in one direction, which is beneficial for maintaining the normal operation of the circuit and improving the performance of the logic circuit 200. Extendably, the cathode of the diode can also be connected to the signal output terminal, which helps to stabilize the voltage output from the signal output terminal.

[0030] In one embodiment, see Figure 2 The logic circuit 200 also includes a fourth resistor R4 and a sixth resistor R6. The first terminal of the first switch G1 is connected to a reference voltage through the sixth resistor R6, and the first terminal of the second switch G2 is connected to a reference voltage through the fourth resistor R4. Specifically, the sixth resistor R6 is connected to the first terminal of the first switch G1 to stabilize the driving function of the first switch G1, and the fourth resistor R6 is connected to the first terminal of the second switch G2 to stabilize the driving function of the second switch G2. Furthermore, the reference voltage reaches the second switch G2 through the fourth resistor R4 and reaches the first switch G1 through the sixth resistor R6. The reference voltage is a fixed DC voltage, connected to the first terminals of both the first and second switches G2, allowing the first and second switches G1 to switch on or off states according to the different levels of the control terminals, ensuring the normal operation of both switches G1 and G2. Alternatively, the first switch G1 can generate a square wave signal to directly control the second switch G2. The control logic must ensure that the second switch G2 is turned on when the square wave is high, achieving the same control effect.

[0031] In one embodiment, see Figure 2 The comparator circuit 300 includes a second comparator L2 and a seventh resistor R7. The second terminal of the logic circuit 200 is connected to the inverting input of the second comparator L2. The inverting input of the second comparator L2 serves as the first terminal of the comparator circuit 300, which is grounded. The non-inverting input of the second comparator L2 serves as the second terminal of the comparator circuit 300, connected to AC power. The output terminal of the second comparator L2 is connected to the third terminal of the logic circuit 200 through the seventh resistor R7. The end of the seventh resistor R7 furthest from the second comparator L2 serves as the third terminal of the comparator circuit 300. When the input signal reaches the non-inverting input of the second comparator L2, the output signal of the logic circuit 200 reaches the inverting input of the second comparator L2 for comparison. The output terminal of the second comparator L2 is connected to the third terminal of the logic circuit 200 through the seventh resistor R7, feeding back the comparison result of the second comparator L2 to the third terminal of the control logic circuit 200 to adjust the duty cycle.

[0032] Specifically, the output of the second comparator L2 depends on the voltage magnitudes of its non-inverting and inverting inputs. When a sinusoidal input signal is applied to the non-inverting input of the second comparator L2, the output of the second comparator L2 will be high when the voltage applied to the non-inverting input is greater than the voltage applied to the inverting input. Taking a square wave generating circuit 100 including a first comparator L1, a first resistor R1, a second resistor R2, and a third resistor R3, and a logic circuit 200 including a first switch G1, a second switch G2, a third switch G3, a diode D1, a fourth resistor R4, and a sixth resistor R6 as an example, when the voltage of the connected AC power enters the positive half-cycle, the output terminal of the first comparator L1 outputs Uout1 at a high level, the first switch G1 is cut off, causing the second switch G2 to conduct. At this time, the voltage U(L2-) output to the inverting terminal of the second comparator L2 is R5 / (R5+R4)*Uref, and the voltage U(L2+) at the non-inverting terminal of the second comparator L2 is the voltage of the connected AC power. When U(L2+)>U(L2-), the output terminal of the second comparator L2 outputs a high level, and the third switch G3 conducts. When the voltage of the connected AC power enters the negative half-cycle, the output Uout1 of the first comparator L1 is low, causing the first switch G1 to turn on and the second switch G2 to turn off. At this time, U(L2-) is always greater than U(L2+), and the output of the second comparator L2 is low, while the third switch G3 is off. This achieves the alternation of positive and negative cycles, ensuring that the period of the output voltage of the second comparator L2 matches the period of the connected AC power, and that the duty cycle of the output signal corresponds to the voltage of the connected AC power.

[0033] In one embodiment, see Figure 2 The comparator circuit 300 also includes a fifth resistor R5 and a second capacitor C2. One end of the second capacitor C2 is connected to the second terminal of the logic circuit 200, and the other end is grounded. One end of the fifth resistor R5 is connected to the inverting input of the second comparator L2, and the other end is grounded. The second capacitor C2 has a voltage stabilizing function, which can prevent positive voltage spikes. When the input AC power reaches the non-inverting input of the second comparator L2, the output signal of the logic circuit 200 is divided by the fifth resistor R5 and then reaches the inverting input of the second comparator L2 for comparison. The signal is then fed back to the logic circuit 200 to adjust the duty cycle.

[0034] In one embodiment, see Figure 2The AC power acquisition circuit also includes a first capacitor C1, through which the square wave generation circuit 100 is connected to AC power. The first capacitor C1 isolates the DC current in the connected AC power, ensuring that the signal received by the square wave generation circuit 100 is AC, thus improving the performance of the square wave generation circuit 100. Extendably, the non-inverting input of the second comparator L2 is also connected to AC power through the first capacitor C1, where the first capacitor C1 still serves to isolate the DC current.

[0035] In one embodiment, see Figure 1 and Figure 2 The AC power acquisition circuit also includes a main control chip receiving circuit 400, and a comparator circuit 300 connected to the signal output terminal through the main control chip receiving circuit 400. The main control chip receiving circuit 400 receives the output terminal of the comparator circuit 300, processes the signal output by the comparator circuit 300, and transmits it to the signal output terminal. The signal output terminal can be used to connect to the main control chip, enabling the main control chip's port to acquire AC power signals.

[0036] Specifically, the structure of the main control chip receiving circuit 400 is not unique. In this embodiment, the main control chip receiving circuit 400 includes a second diode, a third diode, and a resistor. The anode of the second diode is connected to a voltage, the cathode of the third diode is grounded, and the common terminal of the cathode of the second diode and the anode of the third diode is connected to the signal output terminal. One end of the resistor is connected to the second terminal of the logic circuit 200, and the other end is connected to the signal output terminal. Taking a square wave generating circuit 100 including a first comparator L1, a first resistor R1, a second resistor R2, and a third resistor R3, logic circuit 200 including a first switch G1, a second switch G2, a third switch G3, a diode D1, a fourth resistor R4, and a sixth resistor R6, and comparator circuit 300 including a second comparator L2, a seventh resistor R7, a fifth resistor R5, and a second capacitor C2, with the second diode connected to a voltage of 3.3V as an example, the voltage at the common terminal of the cathode of the second diode and the anode of the third diode is equal to the voltage at the signal output terminal. The voltage at the signal output terminal is represented by Uout0. When the first... When comparator L1 outputs Uout1 high, the first switch G1 turns off, causing the second switch G2 to turn on. At this time, U(L2-) is high, and Uout0 is clamped to 3.3V. U(L2-) = R5 / (R5+R4)*Uref. The output Uout2 of the second comparator L2 depends on U(L2+) and U(L2-). U(L2+) is a sinusoidal input signal. Therefore, when U(L2+) > U(L2-), Uout2 is high, the third switch G3 turns on, and U(L2-) is pulled low, becoming low, and Uout0 is low. During this time, U(L2+) > U(L2-) is always satisfied during the positive half-cycle, and Uout0 remains low. When the input AC voltage enters the negative half-cycle, Uout1 outputs a low level, causing the first switch G1 to turn on and the second switch G2 to turn off, and Uout0 outputs a high level. At this time, Uout0 remains at a low level throughout the entire negative half-cycle.

[0037] This achieves alternating positive and negative cycles, ensuring that the output cycle of Uout0 matches that of Uin. The duty cycle of Uout0 is related to the amplitude of the AC voltage Uin. Different voltage amplitudes at the same frequency result in different percentages of Uin reaching R5 / (R5+R4)*Uref, thus ensuring that the amplitude of the AC voltage corresponds to the duty cycle of the output signal. Here, Uref is the reference voltage value connected to the fourth resistor R4 and the sixth resistor R6, and Uin is the AC voltage connected to the AC acquisition circuit. It is understood that in other embodiments, the main control chip receiving circuit 400 can also have other structures, as long as those skilled in the art deem it feasible.

[0038] To better understand the above embodiments, a detailed explanation is provided below with reference to a specific embodiment. In one embodiment, an AC power acquisition circuit is provided, which can be applied to photovoltaic frequency converters and also to all devices involving AC power amplitude and frequency sampling, thus having a wide range of applications. The AC power acquisition circuit includes a square wave generation circuit 100, a logic circuit 200, a comparator circuit 300, and a main control chip receiving circuit 400. The square wave generation circuit 100 includes a first comparator L1, a first resistor R1, a second resistor R2, and a third resistor R3. The logic circuit 200 includes a first switch G1, a second switch G2, a third switch G3, a fourth resistor R4, a sixth resistor R6, and a diode D1. The comparator circuit 300 includes a fifth resistor R5, a second capacitor C2, a second comparator L2, and a seventh resistor R7. The first comparator L1 generates a square wave, which is used to logically control the first switch G1, indirectly controlling the second switch G2. The duty cycle is then adjusted and output through the comparator circuit 300. The sine wave conversion control logic circuit 200 switches the transistor on and off, thereby generating the required frequency-tracking, duty-cycle-adjustable signal, i.e., the desired signal. Diode D1 ensures unidirectional stability of the voltage input to the second comparator L2, and the second capacitor C2 has a voltage stabilizing function to prevent positive voltage spikes. The input signal reaches the non-inverting input of the second comparator L2 through the first capacitor C1. The output signal of logic circuit 200 is divided by the fifth resistor R5 and reaches the inverting input of the second comparator L2 for comparison, and then fed back to logic circuit 200 to adjust the duty cycle.

[0039] This circuit is applied to scenarios requiring over / under voltage and over / under frequency protection in photovoltaic inverters and ordinary inverters, enabling the simultaneous transmission of voltage amplitude and frequency signals through a single input port. It fully utilizes input ports, reducing chip development costs when existing I / O ports are limited. It can quickly detect both over / under voltage and over / under frequency signals. In this circuit, the first capacitor C1 isolates the DC current. The circuit consisting of the sixth resistor R6, the first switch G1, and the second switch G2 primarily stabilizes the driving function of the second switch G2. Alternatively, the first switch G1 can generate a square wave signal to directly control the second switch G2. The control logic must ensure that the second switch G2 conducts when the square wave is high to achieve the same control effect.

[0040] Figure 3This is a flowchart of the AC power acquisition circuit. As shown in the figure, after the AC power acquisition circuit operates normally, it samples the AC power and then determines whether the connected AC power is in the positive half-cycle of a sinusoidal signal. During the positive half-cycle of the AC power, the output voltage Uout1 of the first comparator L1 is high, and during the negative half-cycle, the output voltage of the first comparator L1 is low. When Uout1 is high, the first switch G1 is turned off, causing the second switch G2 to turn on. At this time, the output of the second comparator L2, U(L2-) = R5 / (R5+R4)*Uref, is high. Next, it is determined whether U(L2-) is greater than the voltage amplitude of the connected AC power. If yes, the third switch G3 is turned off; otherwise, the third switch G3 is turned on, U(L2-) is pulled low, and Uout0 becomes low. When the input AC voltage enters the negative half-cycle, Uout1 outputs a low level, causing the first switch G1 to conduct and the second switch G2 to turn off. U(L2-) remains greater than the amplitude of the input AC voltage. The third switch G3 turns off, and Uout0 outputs a high level. During this time, Uout0 remains high throughout the entire negative half-cycle. This achieves alternating positive and negative cycles, ensuring that the output cycle of Uout0 matches the input AC voltage. The duty cycle of Uout0 is related to the amplitude of the input AC voltage. At the same frequency, different voltage amplitudes result in different times for the input AC signal to reach a fixed voltage value R5 / (R5+R4)*Uref. Therefore, this affects the proportion of the output signal's low level duration within a cycle, thus affecting the duty cycle. This allows us to obtain the correlation between amplitude and duty cycle. The AC power acquisition circuit solves the problem that standalone zero-crossing detection only responds to the zero-crossing sampling frequency and cannot acquire over / under voltage signals, and it also solves the problem of low I / O utilization caused by solely acquiring voltage frequency. On one hand, this circuit enables simultaneous transmission and detection of frequency and voltage; on the other hand, it converts voltage into duty cycle and frequency into corresponding periods, providing appropriate detection schemes and improving the interface utilization of the main control chip. It achieves voltage signal transmission via duty cycle and frequency signal transmission via frequency period, allowing a single input port to simultaneously transmit multiple signal states, improving utilization and reducing the need for additional chips required for I / O expansion.

[0041] The aforementioned AC power acquisition circuit includes a square wave generation circuit, a logic circuit, and a comparator circuit. The first terminal of the square wave generation circuit is connected to AC power. The second terminal of the square wave generation circuit is connected to the first terminal of the logic circuit. The second terminal of the logic circuit is connected to the first terminal of the comparator circuit. The second terminal of the comparator circuit is connected to AC power. The third terminal of the comparator circuit is connected to the third terminal of the logic circuit. The second terminal of the logic circuit is connected to the signal output terminal. The square wave generation circuit converts the input AC power into a square wave signal and transmits it to the logic circuit. The logic circuit switches between on and off states based on the high and low levels of the square wave signal. The comparator circuit compares the output signal of the logic circuit with the AC power... The comparison result is fed back to the logic circuit to adjust the duty cycle of the output signal so that the frequency of the output signal matches the frequency of the signal input to the square wave generation circuit. The comparison circuit can adjust the duty cycle of the output signal so that the AC power acquisition circuit can transmit voltage signals through the duty cycle and frequency signals through the frequency period. The frequency of the output signal matches the frequency of the signal input to the square wave generation circuit, so that the output signal can simultaneously acquire the voltage and frequency of the input signal. This enables the simultaneous transmission of multiple signal states through a single port, improving the utilization rate of the output port.

[0042] In one embodiment, an AC power monitoring device is provided, including a main control chip and the aforementioned AC power acquisition circuit. The main control chip is connected to the signal output terminal of the AC power acquisition circuit. The AC power acquisition circuit transmits the output signal to the main control chip through the signal output terminal. The main control chip analyzes the frequency and duty cycle of the received signal. When it detects that the frequency exceeds a preset period range or the duty cycle exceeds a preset duty cycle interval, it performs a corresponding protection procedure and determines the source of the fault. The preset period range and preset duty cycle interval are designed according to the actual circuit requirements. Taking frequency as an example, if the normal operating frequency of the power grid is 50Hz, the preset frequency can be set to less than or equal to 54Hz. When the frequency of the signal transmitted from the signal output terminal exceeds 54Hz, protection should be implemented; otherwise, the system will experience severe fluctuations. The over / under voltage protection value settings are similar; some are national standards, while others are the device's own frequency and voltage requirements. Exceeding these requirements can easily cause damage. Specific settings can be adjusted according to the actual situation.

[0043] The aforementioned AC monitoring device includes a square wave generating circuit, a logic circuit, and a comparator circuit. The first terminal of the square wave generating circuit is connected to AC power. The second terminal of the square wave generating circuit is connected to the first terminal of the logic circuit. The second terminal of the logic circuit is connected to the first terminal of the comparator circuit. The second terminal of the comparator circuit is connected to AC power. The third terminal of the comparator circuit is connected to the third terminal of the logic circuit. The second terminal of the logic circuit is connected to a signal output terminal. The square wave generating circuit converts the input AC power into a square wave signal and transmits it to the logic circuit. The logic circuit switches between on and off states based on the high and low levels of the square wave signal. The comparator circuit compares the output signal of the logic circuit with the AC power... The comparison result is fed back to the logic circuit to adjust the duty cycle of the output signal so that the frequency of the output signal matches the frequency of the signal input to the square wave generation circuit. The comparison circuit can adjust the duty cycle of the output signal so that the AC power acquisition circuit can transmit voltage signals through the duty cycle and frequency signals through the frequency period. The frequency of the output signal matches the frequency of the signal input to the square wave generation circuit, so that the output signal can simultaneously acquire the voltage and frequency of the input signal. This enables the simultaneous transmission of multiple signal states through a single port, improving the utilization rate of the output port.

[0044] An electrical appliance includes an AC power monitoring device as described above. The electrical appliance may be a device that involves sampling the amplitude and frequency of AC power.

[0045] The aforementioned electrical equipment includes a square wave generating circuit, a logic circuit, and a comparator circuit. The first terminal of the square wave generating circuit is connected to AC power. The second terminal of the square wave generating circuit is connected to the first terminal of the logic circuit. The second terminal of the logic circuit is connected to the first terminal of the comparator circuit. The second terminal of the comparator circuit is connected to AC power. The third terminal of the comparator circuit is connected to the third terminal of the logic circuit. The second terminal of the logic circuit is connected to the signal output terminal. The square wave generating circuit converts the input AC power into a square wave signal and transmits it to the logic circuit. The logic circuit switches between on and off states based on the high and low levels of the square wave signal. The comparator circuit compares the output signal of the logic circuit with the AC power... The comparison result is fed back to the logic circuit to adjust the duty cycle of the output signal so that the frequency of the output signal matches the frequency of the signal input to the square wave generation circuit. The comparison circuit can adjust the duty cycle of the output signal so that the AC power acquisition circuit can transmit voltage signals through the duty cycle and frequency signals through the frequency period. The frequency of the output signal matches the frequency of the signal input to the square wave generation circuit, so that the output signal can simultaneously acquire the voltage and frequency of the input signal. This enables the simultaneous transmission of multiple signal states through a single port, improving the utilization rate of the output port.

[0046] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0047] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. An AC current acquisition circuit, characterized in that, It includes a first capacitor, a square wave generating circuit, a logic circuit, and a comparator circuit. The first terminal of the square wave generating circuit is connected to AC power through the first capacitor. The second terminal of the square wave generating circuit is connected to the first terminal of the logic circuit. The second terminal of the logic circuit is connected to the first terminal of the comparator circuit. The second terminal of the comparator circuit is connected to AC power. The third terminal of the comparator circuit is connected to the third terminal of the logic circuit. The second terminal of the logic circuit is connected to a signal output terminal. The square wave generating circuit converts the incoming AC power into a square wave signal and transmits it to the logic circuit. The logic circuit switches between on and off states based on the high and low levels of the square wave signal. The comparison circuit feeds back the comparison result between the output signal of the logic circuit and the AC power to the logic circuit to adjust the duty cycle of the output signal so that the frequency of the output signal matches the frequency of the signal input to the square wave generating circuit. The first capacitor is used to isolate the DC current in the AC power. The logic circuit includes a first switch, a second switch, and a third switch. The control terminal of the first switch is connected to the second terminal of the square wave generating circuit. The first terminal of the first switch is connected to the control terminal of the second switch and is connected to a reference voltage. The first terminal of the second switch is connected to the first terminal of the comparator circuit. The second terminal of the second switch is connected to the first terminal of the third switch. The control terminal of the third switch is connected to the third terminal of the comparator circuit. The second terminals of the third switch and the second terminals of the first switch are both grounded. The switching state of the first switch is different depending on the high and low levels of the square wave signal; the switching state of the second switch is different depending on the switching state of the first switch; when the second switch is in the on or off state, the high and low levels of the signal received by the comparator circuit are different, and the high and low levels of the corresponding output signal are different; the third switch switches between on and off states according to the high and low levels of the output signal of the comparator circuit.

2. The AC power acquisition circuit according to claim 1, characterized in that, The square wave generating circuit includes a first comparator, a first resistor, a second resistor, and a third resistor. One end of the first resistor is connected to AC power, and the other end is connected to the non-inverting input of the first comparator. The inverting input of the first comparator is grounded through the second resistor. The output of the first comparator is connected to the first terminal of the logic circuit.

3. The AC power acquisition circuit according to claim 1, characterized in that, The logic circuit also includes a diode, with the first terminal of the second switching transistor connected to the anode of the diode and the cathode of the diode connected to the first terminal of the comparator circuit.

4. The AC current acquisition circuit according to claim 3, characterized in that, The logic circuit further includes a fourth resistor and a sixth resistor. The first terminal of the first switch is connected to a reference voltage through the sixth resistor, and the first terminal of the second switch is connected to a reference voltage through the fourth resistor.

5. The AC current acquisition circuit according to claim 1, characterized in that, The comparison circuit includes a second comparator and a seventh resistor. The second terminal of the logic circuit is connected to the inverting terminal of the second comparator, the inverting terminal of the second comparator is grounded, the non-inverting terminal of the second comparator is connected to AC power, and the output terminal of the second comparator is connected to the third terminal of the logic circuit through the seventh resistor.

6. The AC power acquisition circuit according to claim 5, characterized in that, The comparison circuit further includes a fifth resistor and a second capacitor. One end of the second capacitor is connected to the second terminal of the logic circuit, and the other end is grounded. One end of the fifth resistor is connected to the inverting terminal of the second comparator, and the other end is grounded.

7. The AC current acquisition circuit according to claim 1, characterized in that, It also includes a main control chip receiving circuit, and the logic circuit is connected to the signal output terminal through the main control chip receiving circuit.

8. The AC power acquisition circuit according to claim 7, characterized in that, The main control chip receiving circuit includes a second diode, a third diode, and a resistor. The anode of the second diode is used to receive voltage, the cathode of the third diode is grounded, and the common terminal of the cathode of the second diode and the anode of the third diode is connected to the signal output terminal. One end of the resistor is connected to the second terminal of the logic circuit, and the other end is connected to the signal output terminal.

9. An AC power monitoring device, characterized in that, It includes a main control chip and an AC power acquisition circuit as described in any one of claims 1-8, wherein the main control chip is connected to the signal output terminal of the AC power acquisition circuit.

10. An electrical appliance, characterized in that, Includes the AC power monitoring device as described in claim 9.

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