Detection circuit, detection system and power converter

Abstract

The invention 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] The present application relates to the field of power electronics technology, and in particular to a detection circuit, a detection system and a power converter. Background Art

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

[0003] In the related technology, a current sampling circuit is generally used to sample the current in the power equipment, and the sampled current signal is converted into a voltage signal. The voltage signal is differentially amplified using an amplifier circuit composed of an operational amplifier, and then input into a comparison circuit in a 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 operational amplifier has a long delay, so that the micro control unit cannot detect the real-time state of the detected current in time. Summary of the invention

[0005] Based on this, it is necessary to provide a detection circuit, detection system and power converter with low delay so that the microcontroller unit can detect the real-time state of the detected current in time to address the above technical problems.

[0006] First, the present application provides a detection circuit, including:

[0007] A sampling circuit, a first circuit and a comparison circuit, wherein:

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

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

[0010] The first circuit is used to convert the sampled current signal into a pulsating voltage signal, and 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 perform comparison processing based on the pulsating voltage signal and the preset comparison voltage signal to obtain a comparison result level, and the comparison result level is used to represent the real-time state of the current to be detected.

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

[0013] The input end of the input circuit is connected to the output end of the sampling circuit to convert the sampled current signal into a voltage signal to obtain an input voltage signal;

[0014] The input end of the resistor voltage divider circuit is connected to the output end of the input circuit, and 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 a pulsating voltage signal, and the target polarity is one of a positive polarity or a negative polarity;

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

[0016] In one embodiment, the resistor voltage divider circuit includes a resistor R1, a resistor R2 and a reference voltage source, wherein:

[0017] A first end of the resistor R1 is connected to the output end of the input circuit, and a second end of the resistor R1 is connected to a first end of the resistor R2 and to a first input end of the comparison circuit;

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

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

[0020] A first end of the resistor R3 is grounded and connected to a first output end of the sampling circuit;

[0021] 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.

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

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

[0024] A first end of the resistor R4 is grounded, and a second end of the resistor R4 is connected to an input end 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 end of the rectifier circuit is connected to the first output end of the sampling circuit, the second input end of the rectifier circuit is connected to the second output end of the sampling circuit, the first output end of the rectifier circuit is grounded, and the second output end of the rectifier circuit is connected to the second end of the resistor R5;

[0027] A first end of the resistor R5 is grounded, and a second end of the resistor R5 is connected to a first input end of the comparison circuit.

[0028] In one of the embodiments, 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 end of the filter circuit is connected to the output end of the first circuit;

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

[0032] In one of the embodiments, the preset comparison voltage signal is an over-current protection voltage signal;

[0033] The comparison circuit is used to perform comparison processing based on the pulsating voltage signal and the overcurrent protection voltage signal to obtain a comparison result level, and 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 of the embodiments, the preset comparison voltage signal is a zero-crossing detection voltage signal;

[0036] The comparison circuit is used to perform comparison processing based on the pulsating voltage signal and the zero-crossing detection reference voltage to obtain a comparison result level, and the comparison result level is used to perform zero-crossing detection processing based on the comparison result level.

[0037] In a second aspect, the present application provides a detection system, including: a sampling circuit, a first circuit and a microcontroller, wherein the microcontroller includes a comparison circuit; wherein:

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

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

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

[0041] The comparison circuit is used for performing comparison processing based on the pulsating voltage signal and the preset comparison voltage signal to obtain a 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] In a third aspect, the present application provides a power converter, comprising the detection phone 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, wherein the detection circuit includes a sampling circuit, a first circuit and a comparison circuit; the input end of the first circuit is connected to the output end of the sampling circuit, the output end of the first circuit is connected to the first input end 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 voltage divider circuit or a rectifier circuit, and does not include an operational amplifier circuit; the comparison circuit is used to compare and process the pulsating voltage signal with a preset comparison voltage signal to obtain a comparison result level, and the comparison result level is used to characterize the real-time state of the current to be detected; in this way, the first circuit used to convert 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 uses a resistor voltage divider circuit or a rectifier circuit to avoid the delay caused by the operational amplifier circuit, resulting in a long response time of the comparison circuit; the detection circuit provided by the above embodiment has a low delay, and the obtained comparison result level can timely reflect the real-time state of the current to be detected in the power equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the related technologies, the drawings required for use in the embodiments or the related technical descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

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

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

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

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

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

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

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

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

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

[0055] Fig.10 is a schematic diagram of an exemplary waveform of a full-wave rectified current signal in one embodiment;

[0056] Fig.11 is a schematic diagram of the structure of a detection circuit provided in another embodiment;

[0057] Fig.12 is a schematic diagram of the structure of a detection circuit provided in another embodiment;

[0058] Fig.13 is a structural block diagram of a detection circuit provided in another embodiment;

[0059] Fig.14 A structural block diagram of a detection system provided in an embodiment.

[0060] Description of reference numerals:

[0061] 100 - sampling circuit; 200 - first circuit; 210 - input circuit; 212 - rectification circuit; 220 - resistance voltage divider circuit; 300 - comparison circuit; 400 - filtering circuit; 500 - microcontroller. DETAILED DESCRIPTION

[0062] In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. Embodiments of the present application are provided in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0063] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0064] It is understood that the terms "first", "second", etc. used in this application may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish a first element from another element. 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 can be understood that the “connection” in the following embodiments should be understood as “electrical connection”, “communication connection”, etc. if the connected circuits, modules, units, etc. have electrical signals or data transmission between each other.

[0066] It is understood that the term "based on" used in this application is used to describe one or more factors that affect the determination, and does not exclude other factors that may affect 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 affects the determination of A, but does not exclude that the determination of A is also based on C.

[0067] When used herein, the singular forms "a", "an", and "said / the" may also include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" and the like specify the presence of stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not exclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. At the same time, the term "and / or" used in this specification includes any and all combinations of the relevant listed items.

[0068] For ease of description, the following embodiments take the scenario of real-time status detection of the current to be detected in the power converter as an example to introduce the detection circuit provided by the present application. It can be understood that the detection circuit provided by the present application can also be used in the scenario of detecting the real-time status of the current in other power equipment.

[0069] Among them, the power converter is a power conversion device used to convert electrical energy from one form to another to achieve energy transmission and control under different power requirements. The power converter can be a micro inverter, energy storage converter, etc. Exemplarily, the micro inverter can convert DC direct current into AC alternating current. The DC end (input) of the micro inverter is connected to the DC source (photovoltaic module), and the AC end (output) of the power converter can be connected to the AC grid and AC equipment.

[0070] In an exemplary embodiment, please refer to Figure 1A detection circuit is provided, comprising: a sampling circuit 100, a first circuit 200 and a comparison circuit 300. The input end of the first circuit 200 is connected to the output end of the sampling circuit 100, and the output end of the first circuit 200 is connected to the first input end 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 is used to convert the current to be detected with a larger amplitude in the power device into a sampled current signal with a smaller amplitude within the detectable range.

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

[0073] In a possible implementation, the sampling circuit 100 may be implemented by 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 circuit includes a resistor voltage 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 comparison circuit 300 is used to perform comparison processing based on the pulsating voltage signal and the 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 polarity of the pulsating voltage signal and the preset comparison voltage signal is consistent.

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

[0078] The second input terminal of the comparison circuit 300 is used to input a preset comparison voltage signal. Exemplarily, the comparison circuit 300 is arranged in an MCU (Microcontroller Unit, also known as a micro control unit) in the power converter, wherein the second input terminal of the comparison circuit 300 is connected to a reference voltage source built in 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, wherein the input end of the first circuit 200 is connected to the output end of the sampling circuit 100, and the output end of the first circuit 200 is connected to the first input end 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, and the first circuit 200 includes a resistor voltage 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 value. The voltage signal is compared and processed to obtain a comparison result level, and the comparison result level is used to characterize the real-time state of the current to be detected; thus, the first circuit 200 for converting 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 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 timely reflect the real-time state of the detected current in the power equipment.

[0080] Please refer to Figure 2 In an exemplary embodiment, the first circuit 200 includes an input circuit 210 and a resistor voltage divider circuit 220, wherein a first end of the input circuit 210 is connected to the output end of the sampling circuit 100, and is used to convert the sampled current signal into a voltage signal to obtain an input voltage signal; a first end of the resistor voltage divider circuit 220 is connected to a second end of the input circuit 210, and the resistor voltage 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; wherein the target polarity is one of a positive pole or a negative pole; a second end of the resistor voltage divider circuit 220 is connected to a first input end of the comparison circuit 300.

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

[0082] Exemplarily, the resistance value of the resistor R1 is the same as the resistance value of the 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 Formula 1:

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

[0084] Among them, V1 is the input voltage signal, that is, Figure 3 , Figure 4 and Figure 5 The voltage value at point A in the figure. Vref is the reference voltage output by the reference voltage power supply; V2 is the pulsating voltage signal, that is, Figure 3 , Figure 4 and Figure 5 The voltage value at point B.

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

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

[0087] In this way, the resistor R3 is connected in parallel with the sampling circuit 100 to convert the sampled current signal output by the sampling circuit 100 into a voltage signal to obtain an input voltage signal. Exemplarily, when the sampling circuit 100 adopts a current transformer (with a transformation ratio of 1:n), the input voltage signal V1=I / n*R1; wherein I represents the current to be detected, and R1 represents the resistance value of the resistor R1.

[0088] In this embodiment, the resistor R3 converts the sampled current signal obtained by the 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. The comparison circuit 300 cannot directly compare and process the input voltage signal V1. At this time, the input voltage signal V1 is adjusted to the target polarity through the resistor voltage divider circuit 220 to obtain a pulsating voltage signal V2. Wherein, the reference voltage V ref The absolute value of is greater than the absolute value of V1. Exemplarily, the amplitude fluctuation range of the input voltage signal V1 is [-0.7V, 0.7V]; the reference voltage V ref The amplitude is 3.3V.

[0089] The resistance value R1 of the resistor R1 and the resistance value R2 of the resistor R2 in the resistor voltage divider circuit 220 are much greater than the resistance value R3 of the resistor R3, so as to avoid the resistor R1 and the resistor R2 affecting the magnitude of the input voltage signal V1 at point A. Optionally, R1=R2=k*R3, wherein k=100 or k=1000 or k=2000; illustratively, R1=R2=1000Ω (ohms), R3=10Ω.

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

[0091] In a possible implementation, the preset comparison voltage signal is a zero-crossing detection voltage signal, exemplarily corresponding to the AC side zero-point voltage of the power converter. Figure 6 , for example, the zero-crossing detection voltage signal is 1.65V, so the comparison circuit 300 outputs a high level when the pulsating voltage signal is greater than 1.65V, and outputs a low level when the pulsating voltage signal is less than or equal to 1.65V; the MCU collects the comparison result level V output by the comparison circuit 300 out The rising and falling edges of the comparison circuit 300 are used to identify the zero-crossing moment of the power converter. For example, when the pulsating voltage signal is greater than 1.65V, the comparison circuit 300 outputs a low level, and when the pulsating voltage signal is less than or equal to 1.65V, the comparison circuit 300 outputs a high level. The MCU collects the comparison result level V output by the comparison circuit 300. out The rising and falling edges of the power converter are used to identify the zero-crossing moment 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 into the comparison circuit 300 purely by resistor voltage division without time delay, so that the identified zero-crossing time is more accurate.

[0093] In a possible implementation, the preset comparison voltage signal is an overcurrent protection voltage signal, which exemplarily corresponds to an 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] Exemplarily, the first overcurrent protection voltage can be set according to the amplitude of the pulsating voltage signal and the peak-to-peak voltage of the pulsating voltage signal. For example, the amplitude of the pulsating voltage signal is A, and the peak-to-peak voltage of the pulsating voltage signal is B, then the first overcurrent protection voltage can be set to B+0.5A; the second overcurrent protection voltage can be set according to the amplitude of the pulsating voltage signal and the valley voltage of the pulsating voltage signal. For example, the amplitude of the pulsating voltage signal is A, and the peak-to-peak voltage of the pulsating voltage signal 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] Setting the first overcurrent protection voltage and the second overcurrent protection voltage in this way can not only accommodate some overshoots during normal startup, but also detect excessive abnormal current.

[0096] Exemplarily, the comparison circuit 300 is used to output a low 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 to output a high level in other cases, wherein the high level triggers overcurrent protection processing for the power converter.

[0097] Also exemplarily, the comparison circuit 300 is used 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 to output a low level in other cases, wherein the low level triggers overcurrent protection processing for the power converter.

[0098] In an optional implementation method 1, the comparison circuit 300 includes a first comparison circuit, a second comparison circuit and a gate circuit. The output end of the first circuit 200 is respectively connected to the first input end of the first comparison circuit and the second comparison circuit. The first comparison 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 comparison 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 a comparison result level based on the first comparison result level and the second comparison result level.

[0099] Exemplarily, the first comparison circuit is used to output a high level when the pulsating voltage signal is less than or equal to the first comparison voltage signal, and to output a low level when the pulsating voltage signal is greater than the first comparison voltage. The second comparison circuit is used to output a high level when the pulsating voltage signal is greater than or equal to the second comparison voltage signal, and to output a low level when the pulsating voltage signal is less than the second comparison voltage. The gate circuit is an AND gate circuit, which is used to output a high level when the first comparison result level and the second comparison result level are both high levels, and to output a low level in other cases, wherein the low level output by the AND gate circuit is used to characterize the existence of an overcurrent condition on the AC side of the power converter, that is, the low level triggers the overcurrent protection operation of the power converter.

[0100] As another example, the logic of the high and low levels output by the first comparison circuit and the second comparison circuit is opposite to that in the previous example, and the gate circuit is implemented using an OR gate circuit. In this example, the high level output by 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 a high level, which triggers the overcurrent protection operation of the power converter.

[0101] In a second optional implementation, the comparison circuit 300 is implemented by a window comparison circuit, and two threshold levels of the window comparison circuit are respectively a first overcurrent protection voltage and a second overcurrent protection voltage.

[0102] In the third optional implementation, the comparison circuit 300 is implemented by a microcontroller or FPGA. In this implementation, the comparison circuit 300 can implement a relatively 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 above three optional implementations, and other achievable comparison circuit 300 structures of 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, Figure 8 As shown, the dotted line represents the overcurrent protection voltage signal, and the solid line represents the pulsating voltage signal. It can be seen that the waveform of the overcurrent protection voltage signal is the same as the waveform of the pulsating voltage signal, and the frequency is the same. Compared with the implementation of using two fixed-size first comparison voltage signals and second comparison voltage signals as the two threshold levels of the comparison circuit, the present implementation adopts the overcurrent protection voltage signal with the same profile as the pulsating voltage signal as the preset comparison voltage signal, so as to avoid that the overcurrent condition can only be detected at the peak moment or the trough moment. In the present implementation, the comparison circuit 300 has a faster response speed to the overcurrent condition, which improves the reliability of using the above 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 end of the rectifier circuit 212 is connected to the first output end of the sampling circuit 100, the second input end of the rectifier circuit 212 is connected to the second output end of the sampling circuit 100, the first output end of the rectifier circuit 212 is grounded, and the second output end of the rectifier circuit 212 is connected to the second end 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 220. Optionally, the resistance value of the resistor R4 is equal to 10Ω.

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

[0107] For example, please refer to Fig. 9 The sampling current signal output by the sampling circuit 100 is an AC signal. The half-wave rectifier circuit rectifies the AC sampling current signal into a half-wave rectified current signal, and then passes through the resistor R4 to output an input voltage signal with the same waveform as the half-wave rectified current signal. After passing through the resistor voltage divider circuit 220, a pulsating voltage signal with the same waveform as the half-wave rectified current signal is obtained; in this way, using Figure 4 Compared with the input circuit 210 shown in FIG. Figure 3 In the implementation shown, in the overcurrent protection scenario, only one preset comparison voltage signal needs to be set, so that the structure of the comparison circuit 300 is relatively simple, the response speed of the comparison circuit 300 is improved, and the hardware cost of the comparison circuit 300 is saved. 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 that of the pulsating voltage signal. Fig. 9 The waveforms of the half-flow rectified current signals shown are the same to increase the response speed of the comparison circuit 300 to an over-current condition.

[0108] Exemplarily, the half-wave rectifier circuit rectifies the AC sampling current signal into a half-wave rectified current signal which may be all negative values ​​and zero values, that is, Fig. 9 The full-wave rectified current signal shown is symmetrically flipped relative to the horizontal axis. In this example, the corresponding setting of the preset comparison voltage signal value and the specific comparison logic can achieve the effects that can be achieved by the detection circuit in the other embodiments mentioned above.

[0109] In adopting Figure 4 In the embodiment of the input circuit 210 shown, in the zero-crossing detection scenario, the preset comparison voltage signal is a zero-crossing detection voltage signal, and the zero-crossing detection voltage signal is a zero level. Exemplarily, 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 collects the comparison result level V output by the comparison circuit 300 out The rising and falling edges of the power converter are used to identify the zero-crossing moment of the power converter.

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

[0111] The switch devices S1 to S6 may be implemented by, but not limited to, diodes, triodes or field effect transistors. Figure 4 In the rectifier circuit 212 shown, the switch device S1 and the switch device S2 are MOS tubes (Metal-Oxide-Semiconductor Field-Effect Transistor) as an example for illustration; Figure 5 In the rectifier circuit 212 shown, diodes are used as an example for the switching device S3, the switching device S4, the switching device S5 and the switching device S6.

[0112] For example, please refer to Fig.10 The sampling current signal output by the 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 the resistor R4, an input voltage signal having the same waveform as the full-wave rectified current signal is output. After passing through the resistor voltage divider circuit 220, a pulsating voltage signal having the same waveform as the full-wave rectified current signal is obtained. In this way, when using Figure 5 The input circuit 210 is shown with Figure 4Similar to the input circuit 210 shown in FIG. 1 , only one preset comparison voltage signal needs to be set, so that the structure of the comparison circuit 300 is relatively simple, the response speed of the comparison circuit 300 is improved, and the hardware cost of the comparison circuit 300 is saved; at the same time, the comparison circuit 300 is adopted. Figure 5 The input circuit 210 shown retains the signal of the negative half cycle in the sampled current signal, thereby 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 that of the pulsating voltage signal. Fig. 9 The waveforms of the full-wave rectified current signals shown are identical to increase the response speed of the comparison circuit 300 to an over-current condition.

[0113] Exemplarily, the full-wave rectifier circuit can rectify the AC sampling current signal into a full-wave rectified current signal that is all negative, that is, Fig.10 The full-wave rectified current signal shown is symmetrically flipped relative to the horizontal axis. In this example, the corresponding setting of the preset comparison voltage signal value and the specific comparison logic can achieve the effects that can be achieved by the detection circuit in the other embodiments mentioned above.

[0114] In adopting Figure 4 In the embodiment of the input circuit 210 shown, in the zero-crossing detection scenario, the preset comparison voltage signal is a zero-crossing detection voltage signal, and the zero-crossing detection voltage signal is a zero level. Exemplarily, 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 collects the comparison result level V output by the comparison circuit 300 out The rising and falling edges of the power converter are used to identify the zero-crossing moment of the power converter.

[0115] In a possible implementation, the rectifier circuit 212 may be configured as follows: Figure 4 and Figure 5 Other rectifier circuit 212 structures other than .

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

[0117] Exemplarily, the rectifier circuit 212 is a half-wave rectifier circuit, such as Fig.11As shown. Exemplarily, the rectifier circuit 212 is a full-wave rectifier circuit, such as Fig.12 shown.

[0118] This embodiment and Figure 4 and Figure 5 The embodiment shown differs in that Fig.11 and Fig.12 In the embodiment shown, there is no need to set up the resistor voltage divider circuit 220. In addition to being able to reduce the response delay, the circuit structure is simpler and has greater reliability and stability.

[0119] In an exemplary embodiment, please refer to Fig.13 , the detection circuit also includes a filter circuit 400, wherein the input end of the filter circuit 400 is connected to the output end of the first circuit 200, and the output end of the filter circuit 400 is connected to the first input end of the comparison circuit 300. In this embodiment, the filter circuit 400 performs filtering processing on the pulsating voltage signal output by the first circuit 200, and obtains the filtered pulsating voltage signal, which is input to the first input end of the comparison circuit 300. The comparison circuit 300 is used to perform comparison processing based on the filtered pulsating voltage signal and the preset comparison voltage signal to obtain a comparison result level. In this embodiment, the filter circuit 400 is arranged 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 the noise interference that may exist 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 , Fig.11 and Fig.12 , the filter circuit 400 adopts a resistor-capacitor filter circuit 400 (RC filter circuit), wherein the filter circuit 400 includes a resistor R6 and a capacitor C1, wherein the first end of the resistor R6 is connected to the output end of the first circuit 200, the second end of the resistor R6 is connected to the first input end of the comparison circuit 300, and is electrolyzed with the first end of the capacitor C1, and the second end of the capacitor C1 is grounded. It can be understood that in this embodiment, the input voltage V of the first input end of the comparison circuit in It is not necessarily exactly the same as the pulsating voltage signal V2 at point B.

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

[0122] In an exemplary embodiment, a detection system is provided, such as Fig.14 As shown, it includes a sampling circuit 100, a first circuit 200 and a microcontroller 500, wherein the microcontroller includes a comparison circuit 300. The input end of the first circuit 200 is connected to the output end of the sampling circuit 100, and the output end of the first circuit 200 is connected to the first input end 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, and the first circuit 200 includes a resistor voltage divider circuit 220 or a rectifier circuit 212, but does not include an operational amplifier circuit; the comparison circuit 300 is used to compare and process 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 with the detection system in the related art, the above-mentioned detection system saves an amplification circuit composed of a first-stage operational amplifier, shortens the detection response time, and enables the microcontroller to respond to changes in the detected current more quickly, thereby achieving more precise control; illustratively, the above-mentioned detection system can improve the response speed of overcurrent protection of power equipment, and improve the accuracy of frequency control of power equipment.

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

[0125] Exemplarily, the detection circuit or the sampling circuit in the detection system is arranged on the AC side of the power converter, and is used to perform real-time status detection on the current on the AC side of the power converter.

[0126] The technical features of the above embodiments may be arbitrarily combined. To make the description concise, 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 above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A detection circuit, characterized in that: The detection circuit comprises: a sampling circuit, a first circuit and a comparison circuit, wherein: The input end of the first circuit is connected to the output end of the sampling circuit, and the output end of the first circuit is connected to the first input end 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, and 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 for performing 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 to represent the real-time state of the current to be detected.

2. The detection circuit according to claim 1, characterized in that: The first circuit includes an input circuit and the resistor voltage divider circuit, wherein: The connection between the input end of the input circuit and the output end of the sampling circuit is used to convert the sampled current signal into a voltage signal to obtain an input voltage signal; The input end of the resistor voltage divider circuit is connected to the output end of the input circuit, and 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, and the target polarity is one of a positive polarity and a negative polarity; The output end of the resistance voltage divider circuit is connected to the first input end of the comparison circuit.

3. The detection circuit according to claim 2, characterized in that: The resistor voltage divider circuit includes a resistor R1, a resistor R2 and a reference voltage power supply, wherein: The first end of the resistor R1 is connected to the output end of the input circuit, and the second end of the resistor R1 is connected to the first end of the resistor R2 and to the first input end of the comparison circuit; The second end of the resistor R2 is connected to the reference voltage power supply.

4. The detection circuit according to claim 2, characterized in that: The input circuit includes a resistor R3, wherein: A first end of the resistor R3 is grounded and connected to a first output end 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 according to claim 2, characterized in that: The input circuit includes the rectifier circuit and resistor R4, wherein: The first input end of the rectifier circuit is connected to the first output end of the sampling circuit, the second input end of the rectifier circuit is connected to the second output end of the sampling circuit, the first output end of the rectifier circuit is grounded, and the second output end of the rectifier circuit is connected to the second end of the resistor R4; A first end of the resistor R4 is grounded, and a second end of the resistor R4 is connected to an input end of the resistor voltage divider circuit.

6. The detection circuit according to claim 1, characterized in that: The first circuit includes the rectifier circuit and a resistor R5; wherein, The first input end of the rectifier circuit is connected to the first output end of the sampling circuit, the second input end of the rectifier circuit is connected to the second output end of the sampling circuit, the first output end of the rectifier circuit is grounded, and the second output end of the rectifier circuit is connected to the second end of the resistor R5; A first end of the resistor R5 is grounded, and a second end of the resistor R5 is connected to a first input end of the comparison 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 according to claim 1, characterized in that: The detection circuit also includes a filter circuit, wherein: The input end of the filter circuit is connected to the output end of the first circuit; The output end of the filter circuit is connected to the first input end of the comparison circuit.

9. The detection circuit according to claim 1, characterized in that: The preset comparison voltage signal is an overcurrent protection voltage signal; The comparison circuit is used to perform comparison processing based on 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 according to claim 9, characterized in that: The frequency of the overcurrent protection voltage signal is the same as the frequency of the pulsating voltage signal.

11. The detection circuit according to claim 1, characterized in that: The preset comparison voltage signal is a zero-crossing detection voltage signal; The comparison circuit is used to perform comparison processing based on the pulsating voltage signal and the zero-crossing detection reference voltage 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 in that: The detection system includes a sampling circuit, a first circuit and a microcontroller, wherein the microcontroller includes a comparison circuit; wherein, The input end of the first circuit is connected to the output end of the sampling circuit, and the output end of the first circuit is connected to the first input end 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, and 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 for performing comparison processing based on the pulsating voltage signal and a preset comparison voltage signal to obtain a 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 in that: The power converter comprises the detection circuit as described in any one of claims 1-11, or comprises the detection system as described in claim 12.

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