Detection circuit, detection system and power converter

Abstract

The utility model relates to a detection circuit, a detection system and a power converter. The detection circuit comprises a sampling circuit, a first circuit and a comparison circuit; the input end of the first circuit is connected with the output end of the sampling circuit, the output end of the first circuit is connected with the first input end of the comparison circuit, and the sampling circuit is used for sampling current to be detected to obtain a sampling current signal; the first circuit is used for converting a sampling current signal into a pulsating voltage signal, and the first circuit comprises a resistance voltage division circuit or a rectifying circuit and does not comprise an operational amplifier circuit; the comparison circuit is used for carrying out comparison processing based on the pulsating voltage signal and a preset comparison voltage signal to obtain a comparison result level, and the comparison result level is used for representing the real-time state of the current to be detected. By adopting the detection circuit, the time delay is relatively low, and the obtained comparison result level can reflect the real-time state of the detected current in the power equipment in time.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, and in particular to a detection circuit, a detection system, and a power converter. Background Technology

[0002] In the field of power electronics, it is generally necessary to detect the current status in power equipment in real time in order to achieve overcurrent protection or power control of the power equipment.

[0003] In related technologies, a current sampling circuit is generally used to sample the current in the power equipment, convert the sampled current signal into a voltage signal, and use an operational amplifier circuit to differentially amplify the voltage signal. Then, the signal is input to the comparison circuit in the microcontroller unit for subsequent comparison and judgment processing to detect the real-time status of the current in the power equipment.

[0004] However, the detection circuit composed of the above-mentioned operational amplifier has a long delay, which makes it impossible for the microcontroller to detect the real-time status of the detected current in a timely manner. Utility Model Content

[0005] Therefore, it is necessary to provide a detection circuit, detection system, and power converter with low latency that enables the microcontroller unit to detect the real-time status of the detected current in a timely manner, in order to address the aforementioned technical problems.

[0006] Firstly, this application provides a detection circuit, including:

[0007] The circuit consists of a sampling circuit, a first circuit, and a comparator circuit, among which...

[0008] The input terminal of the first circuit is connected to the output terminal of the sampling circuit, and the output terminal of the first circuit is connected to the first input terminal of the comparison circuit.

[0009] The sampling circuit is used to sample the current to be detected and obtain the sampled current signal;

[0010] The first circuit is used to convert the sampled current signal into a pulsating voltage signal. The first circuit includes a resistor voltage divider circuit or a rectifier circuit, but does not include an operational amplifier circuit.

[0011] The comparison circuit is used to compare the pulsating voltage signal with the preset comparison voltage signal to obtain the comparison result level. The comparison result level is used to characterize the real-time state of the current to be detected.

[0012] In one embodiment, the first circuit includes an input circuit and a resistor divider circuit, wherein,

[0013] The connection between the input terminal of the input circuit and the output terminal of the sampling circuit is used to convert the sampled current signal into a voltage signal to obtain the input voltage signal.

[0014] The input terminal of the resistor voltage divider circuit is connected to the output terminal of the input circuit. The resistor voltage divider circuit includes a reference voltage power supply, which is used to adjust the input voltage signal to the target polarity based on the reference voltage power supply to obtain a pulsating voltage signal. The target polarity is either positive or negative.

[0015] The output of the resistor divider circuit is connected to the first input of the comparator circuit.

[0016] In one embodiment, the resistor divider circuit includes resistors R1 and R2 and a reference voltage power supply, wherein,

[0017] The first end of resistor R1 is connected to the output terminal of the input circuit, and the second end of resistor R1 is connected to the first end of resistor R2 and to the first input terminal of the comparator circuit.

[0018] The second terminal of resistor R2 is connected to the reference voltage power supply.

[0019] In one embodiment, the input circuit includes a resistor R3, wherein,

[0020] The first terminal of resistor R3 is grounded and connected to the first output terminal of the sampling circuit.

[0021] The second terminal of resistor R3 is connected to the first terminal of the resistor divider circuit and to the second output terminal of the sampling circuit.

[0022] In one embodiment, the input circuit includes a rectifier circuit and a resistor R4, wherein,

[0023] The first input terminal of the rectifier circuit is connected to the first output terminal of the sampling circuit, the second input terminal of the rectifier circuit is connected to the second output terminal of the sampling circuit, the first output terminal of the rectifier circuit is grounded, and the second output terminal of the rectifier circuit is connected to the second terminal of resistor R4.

[0024] The first end of resistor R4 is grounded, and the second end of resistor R4 is connected to the input terminal of the resistor voltage divider circuit.

[0025] In one embodiment, the first circuit includes a rectifier circuit and a resistor R5; wherein,

[0026] The first input terminal of the rectifier circuit is connected to the first output terminal of the sampling circuit, the second input terminal of the rectifier circuit is connected to the second output terminal of the sampling circuit, the first output terminal of the rectifier circuit is grounded, and the second output terminal of the rectifier circuit is connected to the second terminal of resistor R5.

[0027] The first end of resistor R5 is grounded, and the second end of resistor R5 is connected to the first input terminal of the comparator circuit.

[0028] In one embodiment, the rectifier circuit includes a half-wave rectifier circuit or a full-wave rectifier circuit.

[0029] In one embodiment, the detection circuit further includes a filtering circuit, wherein,

[0030] The input terminal of the filter circuit is connected to the output terminal of the first circuit;

[0031] The output of the filter circuit is connected to the first input of the comparator circuit.

[0032] In one embodiment, the preset comparison voltage signal is an overcurrent protection voltage signal;

[0033] The comparator circuit is used to compare the pulsating voltage signal and the overcurrent protection voltage signal to obtain the comparison result level. The comparison result level is used to perform overcurrent protection processing based on the comparison result level.

[0034] In one embodiment, the frequency of the overcurrent protection voltage signal is the same as the frequency of the pulsating voltage signal.

[0035] In one embodiment, the preset comparison voltage signal is a zero-crossing detection voltage signal;

[0036] The comparator circuit is used to compare the pulsating voltage signal and the zero-crossing detection voltage signal to obtain the comparison result level. The comparison result level is then used for zero-crossing detection processing.

[0037] Secondly, this application provides a detection system, comprising: a sampling circuit, a first circuit, and a microcontroller, wherein the microcontroller includes a comparison circuit; wherein,

[0038] The input terminal of the first circuit is connected to the output terminal of the sampling circuit, and the output terminal of the first circuit is connected to the first input terminal of the comparison circuit.

[0039] The sampling circuit is used to sample the current to be detected and obtain the sampled current signal;

[0040] The first circuit is used to convert the sampled current signal into a pulsating voltage signal. The first circuit includes a resistor voltage divider circuit or a rectifier circuit, but does not include an operational amplifier circuit.

[0041] The comparator circuit is used to compare a pulsating voltage signal with a preset comparison voltage signal to obtain the comparison result level.

[0042] The microcontroller is used to determine the real-time state of the current to be detected based on the comparison result level.

[0043] Thirdly, this application provides a power converter, including the detection telephone provided in the first aspect or the detection system provided in the second aspect.

[0044] The detection circuit, detection system, and power converter provided above include a detection circuit comprising a sampling circuit, a first circuit, and a comparison circuit. The input terminal of the first circuit is connected to the output terminal of the sampling circuit, and the output terminal of the first circuit is connected to the first input terminal of the comparison circuit. The sampling circuit is used to sample the current to be detected to obtain a sampled current signal. The first circuit is used to convert the sampled current signal into a pulsating voltage signal. The first circuit includes a resistor divider circuit or a rectifier circuit, but does not include an operational amplifier circuit. The comparison circuit is used to compare the pulsating voltage signal with a preset comparison voltage signal to obtain a comparison result level. The comparison result level is used to characterize the real-time state of the current to be detected. Thus, the first circuit, which converts the sampled current signal obtained by the sampling circuit into a pulsating voltage signal that can be input to the comparison circuit, does not use an operational amplifier circuit, but instead uses a resistor divider circuit or a rectifier circuit, avoiding the delay caused by the operational amplifier circuit, which leads to a long response time for the comparison circuit. The detection circuit provided in the above embodiment has a low delay, and the obtained comparison result level can promptly reflect the real-time state of the current being detected in the power equipment. Attached Figure Description

[0045] To more clearly illustrate the technical solutions in the embodiments or related technologies of this application, the accompanying drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0046] Figure 1 This is a block diagram of the detection circuit provided in one embodiment;

[0047] Figure 2 Here is a block diagram of the detection circuit provided in another embodiment;

[0048] Figure 3 This is a schematic diagram of the detection circuit provided in one embodiment;

[0049] Figure 4 This is a schematic diagram of the detection circuit provided in another embodiment;

[0050] Figure 5 This is a schematic diagram of the detection circuit provided in another embodiment;

[0051] Figure 6 This is an exemplary schematic diagram of the comparison result level in one embodiment;

[0052] Figure 7 This is an exemplary schematic diagram of a preset comparison voltage signal in one embodiment;

[0053] Figure 8 This is an exemplary waveform diagram of a preset comparison voltage signal in another embodiment;

[0054] Figure 9 This is an exemplary waveform diagram of a half-wave rectified current signal in one embodiment;

[0055] Figure 10 This is an exemplary waveform diagram of the full-wave rectified current signal in one embodiment;

[0056] Figure 11 This is a schematic diagram of the detection circuit provided in another embodiment;

[0057] Figure 12 This is a schematic diagram of the detection circuit provided in another embodiment;

[0058] Figure 13 Here is a block diagram of the detection circuit provided in another embodiment;

[0059] Figure 14 This is a block diagram of a detection system provided in one embodiment.

[0060] Explanation of reference numerals in the attached figures:

[0061] 100 - Sampling circuit; 200 - First circuit; 210 - Input circuit; 212 - Rectifier circuit; 220 - Resistor voltage divider circuit; 300 - Comparator circuit; 400 - Filtering circuit; 500 - Microcontroller. Detailed Implementation

[0062] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be more thorough and complete.

[0063] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this application.

[0064] It is understood that the terms "first," "second," etc., used herein may be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of this application, a first resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor.

[0065] It is understood that the term "connection" in the following embodiments should be understood as "electrical connection," "communication connection," etc., if the connected circuits, modules, units, etc., have electrical signal or data transmission with each other.

[0066] It is understood that the term "based on" as used in this application is used to describe one or more factors that influence the determination, but does not exclude other factors that may influence the determination. For example, the phrase "determine A based on B" means that the determination of A can be based entirely or at least partially on factor B. That is, B is a factor that influences the determination of A, but does not exclude the fact that the determination of A is also based on C.

[0067] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising / including” or “having,” etc., specify the presence of the stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. Meanwhile, the term “and / or” as used in this specification includes any and all combinations of the associated listed items.

[0068] For ease of description, the following embodiments use a scenario of real-time status detection of the current to be detected in power converters as an example to introduce the detection circuit provided in this application. It is understood that the detection circuit provided in this application can also be used in scenarios of real-time current status detection in other power equipment.

[0069] A power converter is a power conversion device used to transform electrical energy from one form to another, enabling energy transmission and control under different power requirements. Power converters can be microinverters, energy storage converters, etc. For example, a microinverter can convert DC power to AC power. The DC input of the microinverter is connected to a DC source (photovoltaic modules), and the AC output of the power converter can be connected to the AC power grid and AC equipment.

[0070] In one exemplary embodiment, please refer to Figure 1The provided detection circuit includes a sampling circuit 100, a first circuit 200, and a comparison circuit 300. The input terminal of the first circuit 200 is connected to the output terminal of the sampling circuit 100, and the output terminal of the first circuit 200 is connected to the first input terminal of the comparison circuit 300.

[0071] The sampling circuit 100 samples the current to be detected to obtain a sampled current signal. In this embodiment, the sampling circuit 100 converts the large-amplitude current to be detected in the power equipment into a smaller-amplitude sampled current signal within the detectable range.

[0072] In one possible implementation, the sampling circuit 100 can be implemented using a current transformer (CT). For example, the primary side of the current transformer is connected to the location to be detected on the AC side of the power converter; for example, the primary side of the current transformer is connected to the transformer in the power converter for sampling the current of the transformer's AC winding.

[0073] In one possible implementation, the sampling circuit 100 can be implemented using a Hall effect sensor or a shunt resistor.

[0074] The first circuit 200 is used to convert the sampled current signal into a pulsating voltage signal. The first current includes a resistor divider circuit 220 or a rectifier circuit 212, but does not include an operational amplifier circuit.

[0075] The pulsating voltage signal refers to a voltage signal whose polarity does not change with time, but whose amplitude changes with time. The first circuit 200 converts the sampled current signal into a pulsating voltage signal, so that the polarity of the compared signal input to the comparison circuit 300 remains unchanged.

[0076] The comparator circuit 300 is used to compare a pulsating voltage signal and a preset comparison voltage signal to obtain a comparison result level; wherein, the comparison result level is used to characterize the real-time state of the current to be detected. The pulsating voltage signal and the preset comparison voltage signal have the same polarity.

[0077] The specific magnitude of the preset comparison voltage signal is determined based on the current detection requirements and the specific structure of the first circuit 200.

[0078] The second input terminal of the comparator circuit 300 is used to input a preset comparison voltage signal. For example, the comparator circuit 300 is set in the MCU (Microcontroller Unit) in the power converter, wherein the second input terminal of the comparator circuit 300 is connected to a reference voltage source built into the MCU, and the MCU is used to perform corresponding detection processing based on the comparison result level.

[0079] The detection circuit provided in the above embodiment includes a sampling circuit 100, a first circuit 200, and a comparison circuit 300. The input terminal of the first circuit 200 is connected to the output terminal of the sampling circuit 100, and the output terminal of the first circuit 200 is connected to the first input terminal of the comparison circuit 300. The sampling circuit 100 is used to sample the current to be detected to obtain a sampled current signal. The first circuit 200 is used to convert the sampled current signal into a pulsating voltage signal. The first circuit 200 includes a resistor divider circuit 220 or a rectifier circuit 212, but does not include an operational amplifier circuit. The comparison circuit 300 is used to compare the pulsating voltage signal with a preset comparison circuit. The voltage signal is compared and processed to obtain a comparison result level, which is used to characterize the real-time state of the current to be detected. Thus, the first circuit 200, which converts the sampled current signal obtained by the sampling circuit 100 into a pulsating voltage signal that can be input to the comparison circuit 300, does not use an operational amplifier circuit, but instead uses a resistor divider circuit 220 or a rectifier circuit 212 to avoid the delay caused by the operational amplifier circuit, which leads to a long response time of the comparison circuit 300. The detection circuit provided by the above embodiment has a low delay, and the obtained comparison result level can reflect the real-time state of the current being detected in the power equipment in a timely manner.

[0080] Please refer to Figure 2 In one exemplary embodiment, the first circuit 200 includes an input circuit 210 and a resistor divider circuit 220. The first terminal of the input circuit 210 is connected to the output terminal of the sampling circuit 100 and is used to convert the sampled current signal into a voltage signal to obtain an input voltage signal. The first terminal of the resistor divider circuit 220 is connected to the second terminal of the input circuit 210. The resistor divider circuit 220 includes a reference voltage power supply and is used to adjust the input voltage signal to a target polarity based on the reference voltage power supply to obtain a pulsating voltage signal. The target polarity is either positive or negative. The second terminal of the resistor divider circuit 220 is connected to the first input terminal of the comparator circuit 300.

[0081] In one possible implementation, please refer to Figure 3 , Figure 4 and Figure 5 The resistor voltage divider circuit 220 includes resistors R1 and R2 and a reference voltage power supply. The first end of resistor R1 is connected to the first end of input circuit 210, the second end of resistor R1 is connected to the first end of resistor R2 and to the first input end of comparator circuit 300, and the second end of resistor R2 is connected to the reference voltage power supply.

[0082] For example, the resistance value of resistor R1 is the same as that of resistor R2; the relationship between the pulsating voltage signal output by the resistor voltage divider circuit 220 and the input voltage signal is shown in Equation 1:

[0083] V2=(V ref -V1) / 2+V1=(V ref +V1) / 2, formula 1

[0084] Where V1 is the input voltage signal, i.e. Figure 3 , Figure 4 and Figure 5 The voltage value at point A. Vref is the reference voltage output by the reference voltage power supply; V2 is the pulsating voltage signal, i.e. Figure 3 , Figure 4 and Figure 5 The voltage value at point B.

[0085] For example, resistors R1 and R2 have different resistance values, and the specific conversion relationship between the pulsating voltage signal output by the resistor divider circuit 220 and the input voltage signal is determined based on the resistance values ​​of resistors R1 and R2.

[0086] In one possible implementation, please refer to Figure 3 The input circuit 210 includes a resistor R3, wherein the first end of the resistor R3 is grounded and connected to the first output terminal of the sampling circuit 100, and the second end of the resistor R3 is connected to the first end of the resistor voltage divider circuit 220 and the second output terminal of the sampling circuit 100.

[0087] Thus, resistor R3 is connected in parallel with sampling circuit 100 to convert the sampled current signal output by sampling circuit 100 into a voltage signal, thereby obtaining the input voltage signal. For example, when sampling circuit 100 uses a current transformer (with a transformation ratio of 1:n), the input voltage signal V1 = I / n*R1; where I represents the current to be detected, and R1 represents the resistance value of resistor R1.

[0088] In this implementation, resistor R3 converts the sampled current signal obtained by sampling circuit 100 into an input voltage signal. At this time, the input voltage signal is an AC voltage signal with alternating positive and negative amplitude polarities, making it impossible for comparison circuit 300 to directly compare the input voltage signal V1. Therefore, resistor divider circuit 220 adjusts the input voltage signal V1 to the target polarity to obtain a pulsating voltage signal V2. The reference voltage V... ref The absolute value of V1 is greater than the absolute value of V2. For example, the amplitude fluctuation range of the input voltage signal V1 is [-0.7V, 0.7V]; the reference voltage V2... ref The amplitude is 3.3V.

[0089] In the resistor divider circuit 220, the resistance values ​​of resistors R1 and R2 are much larger than the resistance value of resistor R3, to prevent resistors R1 and R2 from affecting the magnitude of the input voltage signal V1 at point A. Optionally, R1 = R2 = k * R3, where k = 100, k = 1000, or k = 2000; for example, R1 = R2 = 1000 Ω (ohms), R3 = 10 Ω.

[0090] based on Figure 3 In the illustrated implementation, in an exemplary scenario, the sampled current signal is an AC signal, the input voltage signal at point A is a sine wave with a peak of 0.7V and a trough of -0.7V, and the reference voltage Vref = 3.3V. At this time, the pulsating voltage signal is a sine wave with a peak of 2V and a trough of 1.3V. Figure 6 As shown.

[0091] In one possible implementation, the preset comparison voltage signal is a zero-crossing detection voltage signal, exemplarily the AC-side zero-point voltage of the power converter. Please refer to... Figure 6 For example, if the zero-crossing detection voltage signal is 1.65V, then the comparator circuit 300 will output a high level when the pulsating voltage signal is greater than 1.65V, and a low level when the pulsating voltage signal is less than or equal to 1.65V. The MCU will then acquire the comparison result level V output by the comparator circuit 300. out The rising and falling edges of the voltage signal are used to identify the zero-crossing point of the power converter. For example, the comparator circuit 300 outputs a low level when the pulsating voltage signal is greater than 1.65V, and a high level when the pulsating voltage signal is less than or equal to 1.65V; the MCU acquires the comparison result level V output by the comparator circuit 300. out The rising and falling edges are used to identify the zero-crossing time of the power converter.

[0092] In this embodiment, because the first circuit 200 uses a resistor voltage divider circuit 220, the sampled current signal is converted into a pulsating voltage signal that can be input to the comparison circuit 300 by simply relying on resistor voltage division. There is no time delay, which makes the accuracy of the zero-crossing time identified higher.

[0093] In one possible implementation, the preset comparison voltage signal is an overcurrent protection voltage signal, for example, corresponding to the AC side overcurrent protection threshold of the power converter; please refer to Figure 7 The overcurrent protection voltage signal includes a first overcurrent protection voltage and a second overcurrent protection voltage. The first overcurrent protection voltage is determined based on the peak of the pulsating voltage signal, and the second overcurrent protection voltage is determined based on the trough of the pulsating voltage signal.

[0094] For example, the first overcurrent protection voltage can be set based on the amplitude and peak-to-peak voltage of the pulsating voltage signal. For instance, if the amplitude of the pulsating voltage signal is A and the peak-to-peak voltage is B, then the first overcurrent protection voltage can be set to B+0.5A. The second overcurrent protection voltage can be set based on the amplitude and trough voltage of the pulsating voltage signal. For instance, if the amplitude of the pulsating voltage signal is A and the peak-to-peak voltage is C, then the second overcurrent protection voltage can be set to C-0.5A. Wherein, A is greater than 0, B is greater than or equal to 2A, and C is greater than or equal to 0.

[0095] By setting the first and second overcurrent protection voltages in this way, we can accommodate some overshoot during normal startup and detect excessive abnormal current.

[0096] For example, the comparator circuit 300 is configured to output a low level when the pulsating voltage signal is less than or equal to a first overcurrent protection voltage and greater than or equal to a second overcurrent protection voltage, and output a high level in other cases, wherein the high level triggers overcurrent protection processing of the power converter.

[0097] As another example, the comparator circuit 300 is configured to output a high level when the pulsating voltage signal is less than or equal to the first overcurrent protection voltage and the pulsating voltage signal is greater than or equal to the second overcurrent protection voltage, and output a low level in other cases, wherein the low level triggers overcurrent protection processing of the power converter.

[0098] In one optional implementation, the comparator circuit 300 includes a first comparator circuit, a second comparator circuit, and a gate circuit. The output terminal of the first circuit 200 is connected to the first input terminals of the first comparator circuit and the second comparator circuit, respectively. The first comparator circuit is used to perform comparison processing based on the first comparison voltage signal and the pulsating voltage signal to obtain a first comparison result level. The second comparator circuit is used to perform comparison processing based on the second comparison voltage signal and the pulsating voltage signal to obtain a second comparison result level. The gate circuit is used to output the comparison result level based on the first comparison result level and the second comparison result level.

[0099] For example, the first comparator circuit outputs a high level when the pulsating voltage signal is less than or equal to the first comparison voltage signal, and outputs a low level when the pulsating voltage signal is greater than the first comparison voltage. The second comparator circuit outputs a high level when the pulsating voltage signal is greater than or equal to the second comparison voltage signal, and outputs a low level when the pulsating voltage signal is less than the second comparison voltage. The gate circuit is an AND gate circuit, which outputs a high level when both the first comparison result level and the second comparison result level are high, and outputs a low level in other cases. The low level output of the AND gate circuit is used to indicate that there is an overcurrent on the AC side of the power converter, that is, the low level triggers the overcurrent protection operation of the power converter.

[0100] For another example, the logic of the first and second comparator circuits outputting high and low levels is the opposite of the previous example, and the gate circuits are implemented using OR gate circuits. In this example, the high level output of the OR gate circuit is used to characterize the existence of an overcurrent condition on the AC side of the power converter, that is, the comparison result level is high level to trigger the overcurrent protection operation of the power converter.

[0101] Alternatively, in the second implementation, the comparator circuit 300 is implemented using a window comparator circuit, where the two threshold levels of the window comparator circuit are the first overcurrent protection voltage and the second overcurrent protection voltage, respectively.

[0102] Optionally, in the third implementation, the comparator circuit 300 is implemented using a microcontroller or FPGA. In this implementation, the comparator circuit 300 can implement more complex comparison logic.

[0103] It should be noted that the implementation of the comparison circuit 300 involved in this embodiment is not limited to the three optional implementation methods mentioned above. Other comparator circuit 300 structures with the above comparison logic can also be applied to the above detection circuit.

[0104] In one possible implementation, please refer to Figure 8 The frequency of the overcurrent protection voltage signal is the same as the frequency of the pulsating voltage signal. For example, such as... Figure 8 As shown, the dashed lines represent the overcurrent protection voltage signal, and the solid lines represent the pulsating voltage signal. It can be seen that the waveform of the overcurrent protection voltage signal is the same as that of the pulsating voltage signal, and they have the same frequency. Compared to the implementation that uses two fixed-size first and second comparison voltage signals as the two threshold levels of the comparison circuit, this implementation uses an overcurrent protection voltage signal with the same profile as the pulsating voltage signal as the preset comparison voltage signal. This avoids the situation where overcurrent can only be detected at the peak or trough of the waveform. In this implementation, the comparison circuit 300 responds to overcurrent conditions faster, improving the reliability of using the aforementioned detection circuit as the overcurrent protection circuit.

[0105] In one possible implementation, please refer to Figure 4 and Figure 5 The input circuit 210 includes a rectifier circuit 212 and a resistor R4. The first input terminal of the rectifier circuit 212 is connected to the first output terminal of the sampling circuit 100, and the second input terminal of the rectifier circuit 212 is connected to the second output terminal of the sampling circuit 100. The first output terminal of the rectifier circuit 212 is grounded, and the second output terminal of the rectifier circuit 212 is connected to the second terminal of the resistor R4. The first terminal of the resistor R4 is grounded, and the second terminal of the resistor R4 is connected to the input terminal of the resistor voltage divider circuit 220. Optionally, the resistance of the resistor R4 is 10Ω.

[0106] In one possible implementation of this embodiment, such as Figure 4 As shown, rectifier circuit 212 is a half-wave rectifier circuit. For example, the half-wave rectifier circuit includes switching device S1 and switching device S2; wherein, the first terminal of switching device S1 is connected to the first output terminal of sampling circuit 100, and the second terminal of switching device S1 is connected to the first terminal of resistor R4 and then grounded; the first terminal of switching device S2 is connected to the second output terminal of sampling circuit 100, and the second terminal of switching device S2 is connected to the second terminal of resistor R4.

[0107] For example, please refer to Figure 9 The sampling current signal output by sampling circuit 100 is an AC signal. A half-wave rectifier circuit rectifies the AC sampling current signal into a half-wave rectified current signal. After passing through resistor R4, it outputs an input voltage signal with the same waveform as the half-wave rectified current signal. This input voltage signal then passes through resistor divider circuit 220 to obtain a pulsating voltage signal with the same waveform as the half-wave rectified current signal. Thus, using... Figure 4 The input circuit 210 shown is compared to the one using Figure 3 The implementation shown simplifies the overcurrent protection scenario by requiring only one preset comparison voltage signal, thus improving the response speed and reducing hardware costs of the comparison circuit 300. For example, the frequency of the overcurrent protection voltage signal can be the same as the frequency of the pulsating voltage signal, and the waveform of the overcurrent protection voltage signal can be... Figure 9 The waveforms of the half-current rectified current signals shown are the same to improve the response speed of the comparator circuit 300 to overcurrent conditions.

[0108] For example, a half-wave rectifier circuit can rectify a sampled current signal in AC form into a half-wave rectified current signal that is entirely negative and zero, i.e., the half-wave rectified current signal is the same as the sampled current signal in AC form. Figure 9 The full-wave rectified current signal shown is symmetrically flipped relative to the horizontal axis. In this example, setting the value of the preset comparison voltage signal and the specific comparison logic can achieve the effect that the detection circuit in the other embodiments can achieve.

[0109] In Adoption Figure 4 In the embodiment of the input circuit 210 shown, in the zero-crossing detection scenario, the preset comparison voltage signal is the zero-crossing detection voltage signal, which is at a zero level. For example, the comparison circuit 300 outputs a high level when the input pulsating voltage signal is greater than 0V, and outputs a low level when the pulsating voltage signal is equal to 0V; the MCU acquires the comparison result level V output by the comparison circuit 300. out The rising and falling edges are used to identify the zero-crossing time of the power converter.

[0110] In one possible implementation of this embodiment, such as Figure 5 As shown, the rectifier circuit 212 is a full-wave rectifier circuit. Exemplarily, the full-wave rectifier circuit includes switching devices S3, S4, S5, and S6, wherein switching devices S3 and S4 constitute the first bridge arm of the full-wave rectifier circuit, and switching devices S5 and S6 constitute the second bridge arm of the full-wave rectifier circuit. The first output terminal of the sampling circuit 100 is connected to the first bridge arm of the full-wave rectifier circuit, and the second output terminal of the sampling circuit 100 is connected to the second bridge arm of the full-wave rectifier circuit. The first terminal of resistor R4 is grounded, and the second terminal of resistor R4 is connected to the first terminal of the first bridge arm and the first terminal of the second bridge arm. The second terminals of the first bridge arm and the second terminal of the second bridge arm are grounded.

[0111] Among them, the switching devices S1 to S6 can be implemented using, but are not limited to, diodes, transistors, or field-effect transistors. Figure 4 The rectifier circuit 212 shown is illustrated using MOS transistors (Metal-Oxide-Semiconductor Field-Effect Transistors) as an example, with switching devices S1 and S2 as the primary switching devices. Figure 5 The rectifier circuit 212 shown is illustrated using diodes as an example, with switching devices S3, S4, S5 and S6 as the switching components.

[0112] For example, please refer to Figure 10 The sampling current signal output by sampling circuit 100 is an AC signal. The full-wave rectifier circuit rectifies the AC sampling current signal into a full-wave rectified current signal. After passing through resistor R4, it outputs an input voltage signal with the same waveform as the full-wave rectified current signal. This input voltage signal then passes through resistor divider circuit 220 to obtain a pulsating voltage signal with the same waveform as the full-wave rectified current signal. Thus, when using… Figure 5 The input circuit 210 shown is, and Figure 4Similar to the input circuit 210 shown, only one preset comparison voltage signal needs to be set, making the structure of the comparison circuit 300 relatively simple, improving the response speed of the comparison circuit 300, and saving the hardware cost of the comparison circuit 300; at the same time, it adopts Figure 5 The input circuit 210 shown retains the negative half-cycle signal in the sampled current signal, improving the detection accuracy of the overcurrent protection. For example, the frequency of the overcurrent protection voltage signal can be the same as the frequency of the pulsating voltage signal, and the waveform of the overcurrent protection voltage signal is similar to... Figure 9 The waveforms of the full-wave rectified current signals shown are the same to improve the response speed of the comparator circuit 300 to overcurrent conditions.

[0113] For example, the full-wave rectifier circuit can rectify the sampled current signal in AC form into a full-wave rectified current signal that is entirely negative, i.e., equal to... Figure 10 The full-wave rectified current signal shown is symmetrically flipped relative to the horizontal axis. In this example, setting the value of the preset comparison voltage signal and the specific comparison logic can achieve the effect that the detection circuit in the other embodiments can achieve.

[0114] In Adoption Figure 4 In the embodiment of the input circuit 210 shown, in the zero-crossing detection scenario, the preset comparison voltage signal is the zero-crossing detection voltage signal, which is at a zero level. For example, the comparison circuit 300 outputs a high level when the input pulsating voltage signal is greater than 0V, and outputs a low level when the pulsating voltage signal is equal to 0V; the MCU acquires the comparison result level V output by the comparison circuit 300. out The rising and falling edges are used to identify the zero-crossing time of the power converter.

[0115] In one possible implementation, the rectifier circuit 212 can be employed as follows: Figure 4 and Figure 5 Other rectifier circuits 212 structures besides the above.

[0116] Please refer to Figure 11 and Figure 12 In one exemplary embodiment, the first circuit 200 includes a rectifier circuit 212 and a resistor R5. The first input terminal of the rectifier circuit 212 is connected to the first output terminal of the sampling circuit 100, and the second input terminal of the rectifier circuit 212 is connected to the second output terminal of the sampling circuit 100. The first output terminal of the rectifier circuit 212 is grounded, and the second output terminal of the rectifier circuit 212 is connected to the second terminal of the resistor R5. The first terminal of the resistor R5 is grounded, and the second terminal of the resistor R5 is connected to the first input terminal of the comparator circuit 300. Optionally, the resistance value of the resistor R5 is 10Ω.

[0117] For example, rectifier circuit 212 is a half-wave rectifier circuit, such as... Figure 11As shown. For example, rectifier circuit 212 is a full-wave rectifier circuit, such as... Figure 12 As shown.

[0118] This embodiment and Figure 4 and Figure 5 The difference between the embodiments shown is that, Figure 11 and Figure 12 In the embodiment shown, there is no need to set up a resistor voltage divider circuit 220. In addition to reducing response delay, the circuit structure is simpler and the reliability and stability are stronger.

[0119] In one exemplary embodiment, please refer to Figure 13 The detection circuit also includes a filter circuit 400, wherein the input terminal of the filter circuit 400 is connected to the output terminal of the first circuit 200, and the output terminal of the filter circuit 400 is connected to the first input terminal of the comparison circuit 300. In this embodiment, the filter circuit 400 filters the pulsating voltage signal output by the first circuit 200, and the filtered pulsating voltage signal is input to the first input terminal of the comparison circuit 300. The comparison circuit 300 is used to compare the filtered pulsating voltage signal with a preset comparison voltage signal to obtain the comparison result level. In this embodiment, the filter circuit 400 is set between the first circuit 200 and the comparison circuit 300, which can smooth the output waveform of the first circuit 200, improve the stability of the output result of the comparison circuit 300, filter out possible noise interference in the pulsating voltage signal output by the first circuit 200, and improve the accuracy of the output result of the comparison circuit 300.

[0120] In one possible implementation, please combine Figure 3 , Figure 4 , Figure 5 , Figure 11 and Figure 12 The filter circuit 400 employs a resistor-capacitor filter circuit (RC filter circuit), which includes a resistor R6 and a capacitor C1. The first end of resistor R6 is connected to the output terminal of the first circuit 200, and the second end of resistor R6 is connected to the first input terminal of the comparator circuit 300 and electrolytically connected to the first end of capacitor C1. The second end of capacitor C1 is grounded. It can be understood that in this embodiment, the input voltage V at the first input terminal of the comparator circuit... in It is not necessarily exactly the same as the pulsating voltage signal V2 at point B.

[0121] For example, the resistance of resistor R6 is the same as that of resistors R1 and R2. Optionally, the resistance of resistors R6, R1, and R2 is all 1000Ω. Optionally, the capacitance of capacitor C1 is 1nF (nanofarad).

[0122] In one exemplary embodiment, a detection system is provided, such as Figure 14 As shown, the system includes a sampling circuit 100, a first circuit 200, and a microcontroller 500, wherein the microcontroller includes a comparison circuit 300. The input terminal of the first circuit 200 is connected to the output terminal of the sampling circuit 100, and the output terminal of the first circuit 200 is connected to the first input terminal of the comparison circuit 300. The sampling circuit 100 is used to sample the current to be detected to obtain a sampled current signal. The first circuit 200 is used to convert the sampled current signal into a pulsating voltage signal. The first circuit 200 includes a resistor divider circuit 220 or a rectifier circuit 212, but does not include an operational amplifier circuit. The comparison circuit 300 is used to compare the pulsating voltage signal with a preset comparison voltage signal to obtain a comparison result level. The microcontroller 500 is used to determine the real-time state of the current to be detected based on the comparison result level.

[0123] Compared to detection systems in related technologies, the above-mentioned detection system saves the amplification circuit composed of an operational amplifier stage, shortens the detection response time, and enables the microcontroller to respond to changes in the detected current more quickly, achieving more precise control. For example, the above-mentioned detection system can improve the response speed of overcurrent protection for power equipment and improve the accuracy of frequency control for power equipment.

[0124] In one exemplary embodiment, a power converter is provided, which includes any of the detection circuits provided in the above embodiments, or includes the detection system provided in the above embodiments.

[0125] For example, the sampling circuit in the detection circuit or detection system is set on the AC side of the power converter to perform real-time status detection of the current on the AC side of the power converter.

[0126] 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.

[0127] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A detection circuit, characterized by, The detection circuit includes: a sampling circuit, a first circuit, and a comparison circuit, wherein, The input terminal of the first circuit is connected to the output terminal of the sampling circuit, and the output terminal of the first circuit is connected to the first input terminal of the comparison circuit. The sampling circuit is used to sample the current to be detected and obtain a sampled current signal; The first circuit is used to convert the sampled current signal into a pulsating voltage signal. The first circuit includes a resistor divider circuit or a rectifier circuit, but does not include an operational amplifier circuit. The comparison circuit is used to compare the pulsating voltage signal with a preset comparison voltage signal to obtain a comparison result level, which is used to characterize the real-time state of the current to be detected.

2. The detection circuit of claim 1, wherein, The first circuit includes an input circuit and the resistor divider circuit, wherein, The connection between the input terminal of the input circuit and the output terminal of the sampling circuit is used to convert the sampled current signal into a voltage signal to obtain an input voltage signal. The input terminal of the resistor voltage divider circuit is connected to the output terminal of the input circuit. The resistor voltage divider circuit includes a reference voltage power supply, which is used to adjust the input voltage signal to a target polarity based on the reference voltage power supply to obtain the pulsating voltage signal. The target polarity is either a positive pole or a negative pole. The output terminal of the resistor voltage divider circuit is connected to the first input terminal of the comparator circuit.

3. The detection circuit of claim 2, wherein, The resistor divider circuit includes resistor R1, resistor R2, and a reference voltage power supply, wherein, The first end of resistor R1 is connected to the output end of the input circuit, and the second end of resistor R1 is connected to the first end of resistor R2 and to the first input end of the comparator circuit. The second end of the resistor R2 is connected to the reference voltage power supply.

4. The detection circuit of claim 2, wherein, The input circuit includes a resistor R3, wherein... The first terminal of the resistor R3 is grounded and connected to the first output terminal of the sampling circuit. The second end of the resistor R3 is connected to the first end of the resistor voltage divider circuit and to the second output end of the sampling circuit.

5. The detection circuit of claim 2, wherein, The input circuit includes the rectifier circuit and resistor R4, wherein, The first input terminal of the rectifier circuit is connected to the first output terminal of the sampling circuit, the second input terminal of the rectifier circuit is connected to the second output terminal of the sampling circuit, the first output terminal of the rectifier circuit is grounded, and the second output terminal of the rectifier circuit is connected to the second terminal of the resistor R4. The first end of the resistor R4 is grounded, and the second end of the resistor R4 is connected to the input end of the resistor voltage divider circuit.

6. The detection circuit of claim 1, wherein, The first circuit includes the rectifier circuit and resistor R5; wherein, The first input terminal of the rectifier circuit is connected to the first output terminal of the sampling circuit, the second input terminal of the rectifier circuit is connected to the second output terminal of the sampling circuit, the first output terminal of the rectifier circuit is grounded, and the second output terminal of the rectifier circuit is connected to the second terminal of the resistor R5. The first end of the resistor R5 is grounded, and the second end of the resistor R5 is connected to the first input end of the comparator circuit.

7. The detection circuit according to claim 5 or 6, characterized in that, The rectifier circuit includes a half-wave rectifier circuit or a full-wave rectifier circuit.

8. The detection circuit of claim 1, wherein, The detection circuit further includes a filtering circuit, wherein... The input terminal of the filter circuit is connected to the output terminal of the first circuit; The output terminal of the filter circuit is connected to the first input terminal of the comparator circuit.

9. The detection circuit of claim 1, wherein, The preset comparison voltage signal is an overcurrent protection voltage signal; The comparison circuit is used to compare the pulsating voltage signal and the overcurrent protection voltage signal to obtain the comparison result level, and the comparison result level is used to perform overcurrent protection processing based on the comparison result level.

10. The detection circuit of claim 9, wherein, The frequency of the overcurrent protection voltage signal is the same as the frequency of the pulsating voltage signal.

11. The detection circuit of claim 1, wherein, The preset comparison voltage signal is a zero-crossing detection voltage signal; The comparison circuit is used to compare the pulsating voltage signal and the zero-crossing detection voltage signal to obtain the comparison result level, and the comparison result level is used to perform zero-crossing detection processing based on the comparison result level.

12. A detection system characterized by, The detection system includes a sampling circuit, a first circuit, and a microcontroller, wherein the microcontroller includes a comparison circuit; wherein... The input terminal of the first circuit is connected to the output terminal of the sampling circuit, and the output terminal of the first circuit is connected to the first input terminal of the comparison circuit. The sampling circuit is used to sample the current to be detected and obtain a sampled current signal; The first circuit is used to convert the sampled current signal into a pulsating voltage signal. The first circuit includes a resistor voltage divider circuit or a rectifier circuit, but does not include an operational amplifier circuit. The comparison circuit is used to compare the pulsating voltage signal with a preset comparison voltage signal to obtain the comparison result level. The microcontroller is used to determine the real-time state of the current to be detected based on the comparison result level.

13. A power converter, characterized by The power converter includes the detection circuit as described in any one of claims 1-11, or includes the detection system as described in claim 12.

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