Power converter

Abstract

The invention provides a power converter. A direct-current arc detection device arranged in the power converter comprises a first current induction device, a second current induction device and a controller. The first current sensing device is used for sensing the current change of the positive cable and outputting a first voltage signal, the second current sensing device is used for sensing the current change of the negative cable and outputting a second voltage signal, and the controller is used for adjusting the gain ratio between the first voltage signal and the second voltage signal. Therefore, the gain ratio of positive and negative cable sampling signals can be independently adjusted according to the asymmetric working condition of positive and negative cable loops, so that the optimal differential mode signal suppression effect is achieved, the interference of alternating current to ground current on direct current arc detection is reduced to the greatest extent, and the false alarm probability of direct current arc detection is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronics, and in particular to a power converter. Background Art

[0002] After the photovoltaic system is put into use, the long-term exposure of solar photovoltaic panels and other equipment to the open air will lead to aging and other conditions. DC arcs are easily generated inside the photovoltaic system, causing device damage and even fire. Therefore, it is particularly important to accurately monitor the DC arcs generated in the photovoltaic system.

[0003] At present, arc-fault circuit interrupter (AFCI) technology is used to sample relevant signals of the target circuit in the photovoltaic system, such as DC cable current, and infer whether an arc is generated based on the sampled current signal through a detection algorithm, and confirm whether the arc is a real arc based on changes or judgments of the working status of the equipment. If it is confirmed to be a real arc, a protection action is performed, such as shutting down or tripping the equipment, so as to provide protection before the DC arc fault develops into a fire or a short circuit occurs in the circuit.

[0004] Due to the complexity of the environment in which the photovoltaic system is located, different grid environments, different DC cable lengths, different DC side component layouts, etc., often lead to different basic noises in the photovoltaic system. Once the conventional DC arc detection algorithm is developed, there are differences in the recognition ability to deal with different environments. In a noisy environment, false alarms become the biggest bottleneck affecting customer experience. Therefore, how to minimize the interference of AC ground current on DC arc detection when the DC positive and negative circuits of the photovoltaic system are asymmetric is the key to reducing false alarms. Summary of the invention

[0005] The present application provides a power converter for reducing interference of AC current to ground on DC arc detection.

[0006] In a first aspect, the present application provides a power converter, comprising: a power conversion circuit and a DC arc detection device. The power conversion circuit has a DC port for connecting positive and negative cables. The DC arc detection device comprises: a first current sensing device, a second current sensing device and a controller. The first current sensing device is used to connect the positive cable, the second current sensing device is used to connect the negative cable, and the first current sensing device and the second current sensing device are respectively connected to the controller. The first current sensing device is used to sense the current change of the positive cable and output a first voltage signal; the second current sensing device is used to sense the current change of the negative cable and output a second voltage signal; the controller is used to adjust the gain ratio between the first voltage signal and the second voltage signal.

[0007] In the present application, the DC arc detection device sets up independent sampling circuits, i.e., current sensing devices, for the positive and negative cables, so as to independently adjust the gain ratio of the positive and negative cable sampling signals according to the asymmetric working conditions of the positive and negative cable loops, thereby achieving the best differential mode signal suppression effect, minimizing the interference of the AC current to the ground on the DC arc detection, and reducing the false alarm probability of the DC arc detection.

[0008] In some embodiments of the present application, the controller can adjust the gain ratio between the first voltage signal and the second voltage signal by hardware, and the DC arc detection device also includes: a processor; the first current sensing device and the second current sensing device are respectively connected to the processor, and the processor is connected to the controller. The processor is used to merge the first voltage signal and the second voltage signal and output a third voltage signal; the controller is used to adjust the gain ratio between the first voltage signal and the second voltage signal according to the third voltage signal. Specifically, the controller can send a control signal to the first current sensing device alone to adjust the sampling gain coefficient of the first current sensing device on the positive cable to achieve the effect of adjusting the gain ratio between the first voltage signal and the second voltage signal. Alternatively, the controller can send a control signal to the second current sensing device alone to adjust the sampling gain coefficient of the second current sensing device on the negative cable to achieve the effect of adjusting the gain ratio between the first voltage signal and the second voltage signal. Alternatively, the controller can send a control signal to the first current sensing device and the second current sensing device respectively to adjust the sampling gain coefficient of the first current sensing device on the positive cable, and adjust the sampling gain coefficient of the second current sensing device on the negative cable to achieve the effect of adjusting the gain ratio between the first voltage signal and the second voltage signal.

[0009] In some embodiments of the present application, the first current sensing device includes a first current transformer and a first sampling resistor, the primary coil of the first current transformer is wound around the positive cable, one end of the secondary coil of the first current transformer is grounded and connected to one end of the first sampling resistor, and the other end of the secondary coil of the first current transformer is connected to the other end of the first sampling resistor and connected to the first input end of the processor. The second current sensing device includes a second current transformer and a second sampling resistor, the primary coil of the second current transformer is wound around the negative cable, one end of the secondary coil of the second current transformer is grounded and connected to one end of the second sampling resistor, and the other end of the secondary coil of the second current transformer is connected to the other end of the second sampling resistor and connected to the second input end of the processor. The first current transformer is used to isolate and sample the AFCI signal transmitted on the positive cable, remove the DC component therein, and obtain a first current signal; the first sampling resistor is used to convert the first current signal sampled by the first current transformer into a first voltage signal and transmit it to the processor. The second current transformer is used to isolate and sample the AFCI signal transmitted on the negative cable, remove the DC component therein, and obtain a second current signal; the second sampling resistor is used to convert the second current signal sampled by the second current transformer into a second voltage signal and transmit it to the processor. The processor is used to combine the first voltage signal and the second voltage signal to offset or weaken the noise signal in the first voltage signal and the second voltage signal, obtain a third voltage signal and output it to the controller. The controller is used to convert the third voltage signal output by the processor from an analog signal to a digital signal, and then adjust the resistance value ratio of the first sampling resistor and the second sampling resistor according to the size of the noise component in the digital signal, so as to determine the resistance value ratio of the first sampling resistor and the second sampling resistor when the noise component is the lowest, so as to minimize the common mode noise interference. Specifically, the controller can only adjust the resistance value of the first sampling resistor according to the third voltage signal, and the second sampling resistor has a fixed resistance value; or, the controller can only adjust the resistance value of the second sampling resistor according to the third voltage signal, and the first sampling resistor has a fixed resistance value; or, the controller can adjust the resistance value of the first sampling resistor and the resistance value of the second sampling resistor according to the third voltage signal, and the first sampling resistor and the second sampling resistor both use adjustable resistors, which can increase the adjustment range.

[0010] In some embodiments of the present application, a conditioning circuit may be further provided between the controller and the processor, and the conditioning circuit is used to filter the third voltage signal output by the processor to eliminate other frequency interferences.

[0011] In some other embodiments of the present application, the first current sensing device includes a first current transformer and a first conditioning circuit, the primary coil of the first current transformer is wound around the positive cable, one end of the secondary coil of the first current transformer is grounded, the other end of the secondary coil of the first current transformer is connected to the first conditioning circuit, the first conditioning circuit is connected to the processor, and the first conditioning circuit is used to filter and gain the first voltage signal. The second current sensing device includes a second current transformer and a second conditioning circuit, the primary coil of the second current transformer is wound around the negative cable, one end of the secondary coil of the second current transformer is grounded, the other end of the secondary coil of the second current transformer is connected to the second conditioning circuit, the second conditioning circuit is connected to the processor, and the second conditioning circuit is used to filter and gain the second voltage signal. The processor is used to combine the first voltage signal and the second voltage signal to offset or weaken the noise signal in the first voltage signal and the second voltage signal, obtain a third voltage signal and output it to the controller. The controller is used to convert the third voltage signal output by the processor from an analog signal to a digital signal, and then adjust the gain ratio relationship between the first conditioning circuit and the second conditioning circuit according to the size of the noise component in the digital signal, so as to determine the gain ratio relationship between the first conditioning circuit and the second conditioning circuit when the noise component is the lowest, so as to minimize the common mode noise interference. Specifically, the controller can adjust the gain coefficient of the first conditioning circuit according to the third voltage signal, and the second conditioning circuit has a fixed gain coefficient; or, the controller can adjust the gain coefficient of the second conditioning circuit according to the third voltage signal, and the first conditioning circuit has a fixed gain coefficient; or, the controller can adjust the gain coefficient of the first conditioning circuit and the gain coefficient of the second conditioning circuit according to the third voltage signal, and both the first conditioning circuit and the second conditioning circuit use adjustable gain coefficients, which can increase the adjustment range.

[0012] In some other embodiments of the present application, the first current sensing device may further include a first sampling resistor, which is connected in series with the secondary coil of the first current transformer. The second current sensing device may further include a second sampling resistor, which is connected in series with the secondary coil of the second current transformer. The first sampling resistor and the second sampling resistor have fixed resistance values.

[0013] In some embodiments of the present application, since the current transformer can adjust the direction of the secondary current output by controlling the coil winding method, in order to offset or weaken the noise signal in the output third voltage signal, different circuits can be selected as processors according to the coil winding direction.

[0014] In some embodiments of the present application, the winding direction of the positive cable on the first current transformer is opposite to the winding direction of the negative cable on the second current transformer, and the processor is an adding circuit.

[0015] In some other embodiments of the present application, the winding direction of the positive cable on the first current transformer is the same as the winding direction of the negative cable on the second current transformer, and the processor is a subtraction circuit.

[0016] In other embodiments of the present application, the controller can adjust the gain ratio between the first voltage signal and the second voltage signal by software. The first current sensing device includes a first current transformer and a first sampling resistor, the primary coil of the first current transformer is wound around the positive cable, one end of the secondary coil of the first current transformer is grounded, and the other end of the secondary coil of the first current transformer is connected to the controller. The second current sensing device includes a second current transformer and a second sampling resistor, the primary coil of the second current transformer is wound around the negative cable, one end of the secondary coil of the second current transformer is grounded, and the other end of the secondary coil of the second current transformer is connected to the controller. The first sampling resistor and the second sampling resistor have fixed resistance values. The controller is used to convert the first voltage signal and the second voltage signal from analog signals to digital signals respectively, and then calculate the average value of the spectrum amplitude of the noise component frequency band for the first voltage signal and the second voltage signal respectively, and the proportional coefficient of the two average values ​​can be directly obtained. The controller adjusts the gain ratio between the first voltage signal and the second voltage signal by software, and the current signal after suppressing the noise signal can be obtained.

[0017] In other embodiments of the present application, the first current sensing device further includes a first conditioning circuit, the first conditioning circuit is connected between the other end of the secondary coil of the first current transformer and the controller, and the first conditioning circuit is used to filter and gain the first voltage signal at a fixed ratio to eliminate other frequency interference. The second current sensing device further includes a second conditioning circuit, the second conditioning circuit is connected between the other end of the secondary coil of the second current transformer and the controller, and the second conditioning circuit is used to filter and gain the second voltage signal at a fixed ratio to eliminate other frequency interference.

[0018] In some embodiments of the present application, when the power conversion circuit is an inverter circuit, the input side of the inverter circuit has a DC port, and the DC arc detection device performs DC arc detection on the positive and negative cables connected to the input side of the inverter circuit. When the power conversion circuit is a DC-to-DC circuit, both the input and output sides of the DC-to-DC circuit have DC ports, and a first DC arc detection device can be provided in the power converter to perform DC arc detection on the positive and negative cables connected to the input side of the DC-to-DC circuit, and a second DC arc detection device can also be provided in the power converter to perform DC arc detection on the positive and negative cables connected to the output side of the DC-to-DC circuit. When the power conversion circuit is a rectifier circuit, the output side of the rectifier circuit has a DC port, and the DC arc detection device can perform DC arc detection on the positive and negative cables connected to the output side of the rectifier circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram of a photovoltaic system in the prior art;

[0020] Figure 2 Another structural schematic diagram of a photovoltaic system in the prior art;

[0021] Figure 3 A schematic diagram of the structure of a power converter provided in an embodiment of the present application;

[0022] Figure 4a A schematic diagram of the structure of a DC arc detection device in a power converter provided in an embodiment of the present application;

[0023] Figure 4b Another structural schematic diagram of a DC arc detection device in a power converter provided in an embodiment of the present application;

[0024] Figure 5a Another structural schematic diagram of a DC arc detection device in a power converter provided in an embodiment of the present application;

[0025] Figure 5b Another structural schematic diagram of a DC arc detection device in a power converter provided in an embodiment of the present application;

[0026] Figure 6a Another structural schematic diagram of a DC arc detection device in a power converter provided in an embodiment of the present application;

[0027] Figure 6b Another structural schematic diagram of a DC arc detection device in a power converter provided in an embodiment of the present application;

[0028] Figure 7a Another structural schematic diagram of a DC arc detection device in a power converter provided in an embodiment of the present application;

[0029] Figure 7b Another structural schematic diagram of a DC arc detection device in a power converter provided in an embodiment of the present application;

[0030] Figure 8 Another structural schematic diagram of a DC arc detection device in a power converter provided in an embodiment of the present application;

[0031] Fig. 9 Another structural schematic diagram of a DC arc detection device in a power converter provided in an embodiment of the present application. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings. However, the example embodiments can be implemented in various forms and should not be construed as being limited to the embodiments described herein; on the contrary, these embodiments are provided to make the present application more comprehensive and complete, and to fully convey the concepts of the example embodiments to those skilled in the art. The same figure marks in the figures represent the same or similar structures, and thus their repeated descriptions will be omitted. The words expressing position and direction described in this application are all explained using the accompanying drawings as examples, but changes may be made as needed, and all changes are included in the scope of protection of this application. The drawings of this application are only used to illustrate the relative position relationship and do not represent the true proportions.

[0033] It should be noted that specific details are described in the following description to facilitate a full understanding of the present application. However, the present application can be implemented in a variety of other ways different from those described herein, and those skilled in the art can make similar generalizations without violating the connotation of the present application. Therefore, the present application is not limited to the specific implementation methods disclosed below. The subsequent description of the specification is a preferred implementation method for implementing the present application, but the description is for the purpose of illustrating the general principles of the present application and is not intended to limit the scope of the present application. The scope of protection of the present application shall be determined by the definition of the attached claims.

[0034] In order to facilitate understanding of the embodiments of the present application, the relevant technologies involved in the embodiments of the present application are first introduced below.

[0035] The terms used in the following embodiments are only for the purpose of describing specific embodiments and are not intended to be used as limitations on the present application. As used in the specification and appended claims of the present application, the singular expressions "one", "a kind of" and "the" are intended to also include expressions such as "one or more", unless there is a clear indication to the contrary in the context. It should also be understood that in the following embodiments of the present application, "at least one" refers to one, two or more than two.

[0036] References to "one embodiment" and the like described in this specification mean that a particular feature, structure or characteristic described in conjunction with the embodiment is included in one or more embodiments of the present application. Thus, the phrases "in one embodiment", "in some embodiments", "in other embodiments", etc. that appear at different places in this specification do not necessarily all refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0037] Reference Figure 1In the prior art, the AFCI device installed in the photovoltaic system includes a current transformer CT, a conditioning circuit and a control chip. Among them, the current transformer is used to isolate the DC cable, remove the DC component and amplify the voltage amplitude, the conditioning circuit filters the voltage signal, and the control chip analyzes the filtered voltage signal to determine whether there is a DC arc. DC arcs are generally generated at DC interfaces, such as the DC interfaces of each photovoltaic panel and the DC interface of the inverter. The DC arcs generated at the DC interfaces can cause accidents such as fires, so it is necessary to detect the DC arcs and then perform protection actions.

[0038] Since the inverter in the photovoltaic system is a non-isolated system, when the positive and negative line impedances in the photovoltaic system are completely symmetrical, the ground-to-ground current generated by the AC side of the inverter to the DC side is a common-mode current, which will introduce interference to the sampling signal of the current transformer. Figure 2 In the prior art, a unilateral current transformer is adjusted to a common-mode suppression current transformer, and the current signals of the positive and negative cable loops are simultaneously introduced into the magnetic circuit of the current transformer. By adjusting the current directions of the current signals of the positive and negative cable loops in the current transformer, the differential mode current flows in the same direction while the common mode current flows in the opposite direction, ultimately achieving the effect of mutual cancellation of the common mode currents, thereby reducing the interference introduced by the common mode current.

[0039] However, in actual application scenarios, the lengths of positive and negative cables are not consistent, and the positive and negative capacitances of photovoltaic modules to the ground are not symmetrical, which makes the positive and negative line impedances asymmetrical, which will cause part of the ground-to-ground current to be converted into differential mode components. Therefore, simply offsetting the common mode component cannot completely solve the interference problem of ground-to-ground current. How to minimize the interference of AC side ground-to-ground current on DC arc detection and improve detection accuracy when the positive and negative cable loops are asymmetrical is a technical problem that needs to be solved urgently.

[0040] Based on this, the power converter provided in the present application adopts independent sampling methods for the positive and negative cables, and supports independent adjustment of the gain ratio of the positive and negative cable sampling signals, so as to achieve the best ground differential mode signal suppression effect, minimize the interference of AC current to ground on DC arc detection, and reduce the false alarm probability of DC arc detection.

[0041] The power converter provided in the present application is suitable for photovoltaic systems and energy storage systems. For example, the power converter can be used as a photovoltaic inverter to convert the DC power input by the photovoltaic module into AC power output. At this time, the DC cable connected to the DC input port of the photovoltaic inverter can be subjected to DC arc detection. For another example, the power converter can be used as a photovoltaic optimizer to track the maximum power point of the DC power input by the photovoltaic module. At this time, the DC arc detection can be performed on the DC cable connected to the DC input port of the photovoltaic optimizer, and the DC arc detection can also be performed on the DC cable connected to the DC output port of the photovoltaic optimizer. For another example, the power converter can be used as an energy storage DC-to-DC converter to output the DC power input by the energy storage battery after voltage conversion. At this time, the DC arc detection can be performed on the DC cable connected to the DC input port of the energy storage DC-to-DC converter, and the DC cable connected to the DC output port of the energy storage DC-to-DC converter can also be subjected to DC telephone detection.

[0042] Reference Figure 3 , the power converter provided in the present application specifically includes: a power conversion circuit 100 and a DC arc detection device 200. The power conversion circuit has a DC port for connecting positive and negative cables. Specifically, when the power conversion circuit 100 is an inverter circuit, the input side of the inverter circuit has a DC port, and the DC arc detection device 200 can perform DC arc detection on the positive and negative cables connected to the input side of the inverter circuit. When the power conversion circuit 100 is a DC-to-DC circuit, the input side and / or output side of the DC-to-DC circuit both have a DC port, and a first DC arc detection device can be set in the power converter to perform DC arc detection on the positive and negative cables connected to the input side of the DC-to-DC circuit, and a second DC arc detection device can also be set in the power converter to perform DC arc detection on the positive and negative cables connected to the output side of the DC-to-DC circuit. When the power conversion circuit 100 is a rectifier circuit, the output side of the rectifier circuit has a DC port, and the DC arc detection device 200 can perform DC arc detection on the positive and negative cables connected to the output side of the rectifier circuit. Figure 3 The power conversion circuit 100 is described as a two-stage inverter including a DC / DC converter circuit and an inverter circuit DC / AC.

[0043] In the present application, the DC arc detection device 200 sets independent sampling circuits, i.e., current sensing devices, for the positive and negative cables, so as to independently adjust the gain ratio of the positive and negative cable sampling signals for the asymmetric working conditions of the positive and negative cable loops, thereby achieving the best differential mode signal suppression effect, minimizing the interference of the AC current to the ground on the DC arc detection, and reducing the false alarm probability of the DC arc detection. Specifically, the DC arc detection device 200 includes: a first current sensing device, a second current sensing device, and a controller. Among them, the first current sensing device is used to connect the positive cable, the second current sensing device is used to connect the negative cable, and the first current sensing device and the second current sensing device are respectively connected to the controller. The first current sensing device is used to sense the current change of the positive cable and output a first voltage signal, the second current sensing device is used to sense the current change of the negative cable and output a second voltage signal, and the controller is used to adjust the gain ratio between the first voltage signal and the second voltage signal. The controller can specifically use a microcontroller unit (MCU) to implement its functions.

[0044] In actual application, after the power converter is turned on, the controller can perform an action of adjusting the gain ratio between the first voltage signal and the second voltage signal, and then perform an action of fine-tuning the gain ratio between the first voltage signal and the second voltage signal in a timely or real-time manner.

[0045] In some embodiments of the present application, the controller can adjust the gain ratio between the first voltage signal and the second voltage signal by hardware. Figure 3 , the DC arc detection device 200 may also include: a processor. The first current sensing device and the second current sensing device are respectively connected to the processor, and the processor is connected to the controller. The processor is used to merge the first voltage signal and the second voltage signal and output a third voltage signal, and the controller is used to adjust the gain ratio between the first voltage signal and the second voltage signal according to the third voltage signal. Specifically, the controller can send a control signal to the first current sensing device alone to adjust the sampling gain coefficient of the first current sensing device on the positive cable to achieve the effect of adjusting the gain ratio between the first voltage signal and the second voltage signal. Alternatively, the controller can send a control signal to the second current sensing device alone to adjust the sampling gain coefficient of the second current sensing device on the negative cable to achieve the effect of adjusting the gain ratio between the first voltage signal and the second voltage signal. Alternatively, the controller can send a control signal to the first current sensing device and the second current sensing device respectively, adjust the sampling gain coefficient of the first current sensing device on the positive cable, and adjust the sampling gain coefficient of the second current sensing device on the negative cable to achieve the effect of adjusting the gain ratio between the first voltage signal and the second voltage signal.

[0046] The following is a specific example to illustrate how the controller adjusts the sampling gain coefficient through hardware.

[0047] Embodiment 1:

[0048] Reference Figure 4a and Figure 4b In this embodiment, the first current sensing device may specifically include a first current transformer CT1 and a first sampling resistor R1. The first current transformer CT1 is connected to the positive cable, the first sampling resistor R1 is connected to the first current transformer CT1, and the processor is connected to the first sampling resistor R1. Specifically, the primary coil of the first current transformer CT1 is wound around the positive cable, one end of the secondary coil of the first current transformer CT1 is grounded and connected to one end of the first sampling resistor R1, and the other end of the secondary coil of the first current transformer CT1 is connected to the other end of the first sampling resistor R1 and connected to the first input end of the processor. The first current transformer CT1 is used to isolate and sample the AFCI signal transmitted on the positive cable, remove the DC component therein, and obtain a first current signal; the first sampling resistor R1 is used to convert the first current signal sampled by the first current transformer CT1 into a first voltage signal and transmit it to the processor.

[0049] The second current sensing device may specifically include a second current transformer CT2 and a second sampling resistor R2, the second current transformer CT2 is connected to the negative cable, the second sampling resistor R2 is connected to the second current transformer CT2, and the processor is connected to the second sampling resistor R2. Specifically, the primary coil of the second current transformer CT2 is wound around the negative cable, one end of the secondary coil of the second current transformer CT2 is grounded and connected to one end of the second sampling resistor R2, and the other end of the secondary coil of the second current transformer CT2 is connected to the other end of the second sampling resistor R1 and connected to the second input end of the processor. The second current transformer CT2 is used to isolate and sample the AFCI signal transmitted on the negative cable, remove the DC component therein, and obtain a second current signal; the second sampling resistor R2 is used to convert the second current signal sampled by the second current transformer CT2 into a second voltage signal and transmit it to the processor.

[0050] In this embodiment, the processor is used to combine the first voltage signal and the second voltage signal to cancel or weaken the noise signal in the first voltage signal and the second voltage signal, obtain a third voltage signal and output it to the controller. Since the current transformer can adjust the direction of the secondary current output by controlling the coil winding method, in order to cancel or weaken the noise signal in the output third voltage signal, different circuits can be selected as processors according to the coil winding direction.

[0051] Reference Figure 4aIn some embodiments of the present application, when the winding direction of the positive cable on the first current transformer CT1 is opposite to the winding direction of the negative cable on the second current transformer CT2, the directions of the first voltage signal and the second voltage signal are opposite. Therefore, the processor can specifically use an adding circuit to add the first voltage signal and the second voltage signal to obtain a third voltage signal after suppressing common mode noise.

[0052] Reference Figure 4b In some other embodiments of the present application, when the winding direction of the positive cable on the first current transformer CT1 is the same as the winding direction of the negative cable on the second current transformer CT2, the directions of the first voltage signal and the second voltage signal are the same. Therefore, the processor can specifically use a subtraction circuit to subtract the first voltage signal from the second voltage signal to obtain a third voltage signal after suppressing common mode noise.

[0053] In this embodiment, the controller is used to convert the analog signal output by the processor into a digital signal, that is, to convert the third voltage signal into a digital signal, and then adjust the resistance value ratio of the first sampling resistor R1 and the second sampling resistor R2 according to the size of the noise component in the digital signal, so as to determine the resistance value ratio of the first sampling resistor R1 and the second sampling resistor R2 when the lowest noise component is obtained, so as to minimize common-mode noise interference.

[0054] Reference Figure 4a and Figure 4b A conditioning circuit may also be provided between the controller and the processor, and the conditioning circuit is used to filter the third voltage signal output by the processor to eliminate other frequency interferences.

[0055] Reference Figure 5aIn some embodiments of the present application, the controller can adjust only the resistance value of the first sampling resistor R1 according to the third voltage signal, and the second sampling resistor R2 has a fixed resistance value. Exemplarily, after the power converter is turned on, the controller can control the first sampling resistor R1 to be in a default resistance state, generally R1=R2. The controller reads the third voltage signal, performs a fast Fourier transform (FFT) on the third voltage signal, screens out the noise component frequency band after excluding the system operating frequency, and calculates the average value of the spectrum amplitude of the noise component frequency band. Increase or decrease the resistance value of the first sampling resistor R1 to disturb the sampling data of the positive cable, recalculate the average value of the spectrum amplitude of the noise component frequency band, and observe the change of the average value. If the average value increases, it means that it is necessary to disturb in the opposite direction. At this time, reduce or increase the resistance value of the first sampling resistor R1, and it can be expected that the average value will decrease until the average value no longer decreases and begins to increase, indicating that the resistance value of the first sampling resistor R1 is adjusted. At this time, the average value of the spectrum amplitude of the noise component frequency band is the smallest. If the average value decreases, it means that the disturbance direction is correct. At this time, continue to increase or decrease the resistance value of the first sampling resistor R1, and it can be expected that the average value will decrease. Until the average value no longer decreases and starts to increase, it means that the resistance value of the first sampling resistor R1 is adjusted. At this time, the average value of the spectrum amplitude of the noise component frequency band is the smallest.

[0056] Reference Figure 5b In some other embodiments of the present application, the controller may also adjust the resistance value of the second sampling resistor R2 according to the third voltage signal, and the first sampling resistor R1 has a fixed resistance value. Exemplarily, after the power converter is turned on, the controller may control the second sampling resistor R2 to be in a default resistance state, generally R2=R1. The controller reads the third voltage signal, performs a fast Fourier transform (FFT) on the third voltage signal, screens out the noise component frequency band after excluding the system operating frequency, and calculates the average value of the spectrum amplitude of the noise component frequency band. Increase or decrease the resistance value of the second sampling resistor R2 to disturb the sampled data of the negative cable, recalculate the average value of the spectrum amplitude of the noise component frequency band, and observe the change of the average value. If the average value increases, it means that it is necessary to disturb in the opposite direction. At this time, the resistance value of the second sampling resistor R2 is reduced or increased, and it can be expected that the average value will decrease until the average value no longer decreases and begins to increase, indicating that the resistance value of the second sampling resistor R2 is adjusted. At this time, the average value of the spectrum amplitude of the noise component frequency band is the smallest. If the average value decreases, it means that the disturbance direction is correct. At this time, the resistance value of the second sampling resistor R2 continues to increase or decrease, and it can be expected that the average value will decrease. Until the average value no longer decreases and starts to increase, it means that the resistance value of the second sampling resistor R2 is adjusted. At this time, the average value of the spectrum amplitude of the noise component frequency band is the smallest.

[0057] Reference Figure 4a and Figure 4b In some other embodiments of the present application, the controller can also adjust the resistance value of the first sampling resistor R1 and the resistance value of the second sampling resistor R2 according to the third voltage signal. The first sampling resistor R1 and the second sampling resistor R2 both use adjustable resistors, which can increase the adjustment range. Exemplarily, after the power converter is turned on, the controller can control the first sampling resistor R1 and the second sampling resistor R2 to be in a default resistance state, generally R1=R2. The controller reads the third voltage signal, performs a fast Fourier transform (FFT) on the third voltage signal, screens out the noise component frequency band after excluding the system operating frequency, and calculates the average value of the spectrum amplitude of the noise component frequency band. First, fix the resistance value of the second sampling resistor R2, increase or decrease the resistance value of the first sampling resistor R1, so as to disturb the sampling data of the positive cable, recalculate the average value of the spectrum amplitude of the noise component frequency band, and observe the change of the average value. If the average value increases, it means that it is necessary to disturb in the opposite direction. At this time, the resistance value of the first sampling resistor R1 is reduced or increased, and it can be expected that the average value will decrease until the average value no longer decreases and begins to increase, indicating that the resistance value of the first sampling resistor R1 has been adjusted, and the average value of the spectrum amplitude of the noise component frequency band is the smallest. If the average value decreases, it means that the disturbance direction is correct. At this time, continue to increase or decrease the resistance value of the first sampling resistor R1, and it can be expected that the average value will decrease until the average value no longer decreases and begins to increase, indicating that the resistance value of the first sampling resistor R1 has been adjusted, and the average value of the spectrum amplitude of the noise component frequency band is the smallest. Afterwards, fix the resistance value of the first sampling resistor R1, increase or decrease the resistance value of the second sampling resistor R2, so as to disturb the sampling data of the negative cable, recalculate the average value of the spectrum amplitude of the noise component frequency band, and observe the change of the average value. If the average value increases, it means that the disturbance needs to be made in the opposite direction. At this time, the resistance value of the second sampling resistor R2 is reduced or increased, and it can be expected that the average value will decrease until the average value stops decreasing and starts to increase, indicating that the resistance value of the second sampling resistor R2 has been adjusted, and the average value of the spectrum amplitude of the noise component frequency band is the smallest. If the average value decreases, it means that the disturbance direction is correct. At this time, the resistance value of the second sampling resistor R2 is continued to be increased or decreased, and it can be expected that the average value will decrease until the average value stops decreasing and starts to increase, indicating that the resistance value of the second sampling resistor R2 has been adjusted, and the average value of the spectrum amplitude of the noise component frequency band is the smallest.

[0058] Embodiment 2:

[0059] Reference Figure 6a and Figure 6bIn this embodiment, the first current sensing device may specifically include a first current transformer CT1 and a first conditioning circuit. The first current transformer CT1 is connected to the positive cable, the first conditioning circuit is connected to the first current transformer CT1, and the first conditioning circuit is connected to the processor. The first current sensing device also includes a first sampling resistor R1 with a fixed resistance value, and the first sampling resistor R1 is connected to the first current transformer CT1. Specifically, the primary coil of the first current transformer CT1 is wound around the positive cable, one end of the secondary coil of the first current transformer CT1 is grounded and connected to one end of the first sampling resistor R1, the other end of the secondary coil of the first current transformer CT1 is connected to the other end of the first sampling resistor R1 and is connected to the input end of the first conditioning circuit, and the output end of the first conditioning circuit is connected to the first input end of the processor. The first current transformer CT1 is used to isolate and sample the AFCI signal transmitted on the positive cable, remove the DC component therein, and obtain a first current signal; the first sampling resistor R1 is used to convert the first current signal sampled by the first current transformer CT1 into a first voltage signal and transmit it to the first conditioning circuit, and the first conditioning circuit is used to filter and gain the first voltage signal and output it to the processor.

[0060] The second current sensing device may specifically include a second current transformer CT2 and a second conditioning circuit. The second current transformer CT2 is connected to the negative cable, the second conditioning circuit is connected to the second current transformer CT2, and the second conditioning circuit is connected to the processor. The second current sensing device also includes a second sampling resistor R2 with a fixed resistance value, and the second sampling resistor R2 is connected to the second current transformer CT2. Specifically, the primary coil of the second current transformer CT2 is wound around the negative cable, one end of the secondary coil of the second current transformer CT2 is grounded and connected to one end of the second sampling resistor R2 at the same time, the other end of the secondary coil of the second current transformer CT2 is connected to the other end of the second sampling resistor R2 and is also connected to the input end of the second conditioning circuit, and the output end of the second conditioning circuit is connected to the second input end of the processor. The second current transformer CT2 is used to isolate and sample the AFCI signal transmitted on the negative cable, remove the DC component therein, and obtain a second current signal; the second sampling resistor R2 is used to convert the second current signal sampled by the second current transformer CT2 into a second voltage signal and transmit it to the second conditioning circuit, and the second conditioning circuit is used to filter the second voltage signal and output it to the processor.

[0061] In this embodiment, the processor is used to combine the first voltage signal and the second voltage signal to cancel or weaken the noise signal in the first voltage signal and the second voltage signal, obtain a third voltage signal and output it to the controller. Since the current transformer can adjust the direction of the secondary current output by controlling the coil winding method, in order to cancel or weaken the noise signal in the output third voltage signal, different circuits can be selected as processors according to the coil winding direction.

[0062] Reference Figure 6a In some embodiments of the present application, when the winding direction of the positive cable on the first current transformer CT1 is opposite to the winding direction of the negative cable on the second current transformer CT2, the directions of the first voltage signal and the second voltage signal are opposite. Therefore, the processor can specifically use an adding circuit to add the first voltage signal and the second voltage signal to obtain a third voltage signal after suppressing common mode noise.

[0063] Reference Figure 6b In some other embodiments of the present application, when the winding direction of the positive cable on the first current transformer CT1 is the same as the winding direction of the negative cable on the second current transformer CT2, the directions of the first voltage signal and the second voltage signal are the same. Therefore, the processor can specifically use a subtraction circuit to subtract the first voltage signal from the second voltage signal to obtain a third voltage signal after suppressing common mode noise.

[0064] In this embodiment, the controller is used to convert the analog signal output by the processor into a digital signal, that is, to convert the third voltage signal into a digital signal, and then adjust the gain ratio relationship between the first conditioning circuit and the second conditioning circuit according to the size of the noise component in the digital signal, so as to determine the gain ratio relationship between the first conditioning circuit and the second conditioning circuit when the lowest noise component is obtained, so as to minimize common-mode noise interference.

[0065] Reference Figure 7aIn some embodiments of the present application, the controller can adjust only the gain coefficient of the first conditioning circuit according to the third voltage signal, and the second conditioning circuit has a fixed gain coefficient. Exemplarily, after the power converter is turned on, the controller can control the first conditioning circuit to be in a default gain coefficient, and generally the gain coefficient of the first conditioning circuit is equal to the gain coefficient of the second conditioning circuit. The controller reads the third voltage signal, performs a fast Fourier transform (FFT) on the third voltage signal, screens out the noise component frequency band after excluding the system operating frequency, and calculates the average value of the spectrum amplitude of the noise component frequency band. Increase or decrease the gain coefficient of the first conditioning circuit to disturb the sampled data of the positive cable, recalculate the average value of the spectrum amplitude of the noise component frequency band, and observe the change of the average value. If the average value increases, it means that it is necessary to disturb in the opposite direction. At this time, reduce or increase the gain coefficient of the first conditioning circuit, and it can be expected that the average value will decrease until the average value no longer decreases and begins to increase, indicating that the gain coefficient of the first conditioning circuit is adjusted. At this time, the average value of the spectrum amplitude of the noise component frequency band is the smallest. If the average value decreases, it means that the disturbance direction is correct. At this time, continue to increase or decrease the gain coefficient of the first conditioning circuit, and it can be expected that the average value will decrease. Until the average value no longer decreases and begins to increase, it means that the gain coefficient of the first conditioning circuit has been adjusted. At this time, the average value of the spectrum amplitude of the noise component frequency band is the smallest.

[0066] Reference Figure 7bIn some other embodiments of the present application, the controller may also adjust the gain coefficient of the second conditioning circuit according to the third voltage signal, and the first conditioning circuit has a fixed gain coefficient. Exemplarily, after the power converter is turned on, the controller may control the second conditioning circuit to be in a default gain coefficient, and generally the gain coefficient of the second conditioning circuit is equal to the gain coefficient of the first conditioning circuit. The controller reads the third voltage signal, performs a fast Fourier transform (FFT) on the third voltage signal, screens out the noise component frequency band after excluding the system operating frequency, and calculates the average value of the spectrum amplitude of the noise component frequency band. Increase or decrease the gain coefficient of the second conditioning circuit to disturb the sampled data of the negative cable, recalculate the average value of the spectrum amplitude of the noise component frequency band, and observe the change of the average value. If the average value increases, it means that it is necessary to disturb in the opposite direction. At this time, the gain coefficient of the second conditioning circuit is reduced or increased, and it can be expected that the average value will decrease until the average value no longer decreases and begins to increase, indicating that the gain coefficient of the second conditioning circuit is adjusted. At this time, the average value of the spectrum amplitude of the noise component frequency band is the smallest. If the average value decreases, it means that the disturbance direction is correct. At this time, continue to increase or decrease the gain coefficient of the second conditioning circuit. It can be expected that the average value will decrease. Until the average value no longer decreases and begins to increase, it means that the gain coefficient of the second conditioning circuit has been adjusted. At this time, the average value of the spectrum amplitude of the noise component frequency band is the smallest.

[0067] Reference Figure 6a and Figure 6bIn some other embodiments of the present application, the controller can also adjust the gain coefficient of the first conditioning circuit and the gain coefficient of the second conditioning circuit according to the third voltage signal. Both the first conditioning circuit and the second conditioning circuit adopt adjustable gain coefficients, which can increase the adjustment range. Exemplarily, after the power converter is turned on, the controller can control the first conditioning circuit and the second conditioning circuit to be at a default gain coefficient, which is generally equal to each other. The controller reads the third voltage signal, performs a fast Fourier transform (FFT) on the third voltage signal, screens out the noise component frequency band after excluding the system operating frequency, and calculates the average value of the spectrum amplitude of the noise component frequency band. First, fix the gain coefficient of the second conditioning circuit, increase or decrease the gain coefficient of the first conditioning circuit to disturb the sampling data of the positive cable, recalculate the average value of the spectrum amplitude of the noise component frequency band, and observe the change of the average value. If the average value increases, it means that it is necessary to disturb in the opposite direction. At this time, the gain coefficient of the first conditioning circuit is reduced or increased, and it can be expected that the average value will decrease until the average value no longer decreases and begins to increase, indicating that the gain coefficient of the first conditioning circuit has been adjusted, and the average value of the spectrum amplitude of the noise component frequency band is the smallest. If the average value decreases, it means that the disturbance direction is correct. At this time, continue to increase or decrease the gain coefficient of the first conditioning circuit, and it can be expected that the average value will decrease until the average value no longer decreases and begins to increase, indicating that the gain coefficient of the first conditioning circuit has been adjusted, and the average value of the spectrum amplitude of the noise component frequency band is the smallest. Afterwards, fix the gain coefficient of the first conditioning circuit, increase or decrease the gain coefficient of the second conditioning circuit, so as to disturb the sampled data of the negative cable, recalculate the average value of the spectrum amplitude of the noise component frequency band, and observe the change of the average value. If the average value increases, it means that it is necessary to disturb in the opposite direction. At this time, reduce or increase the gain coefficient of the second conditioning circuit, and it can be expected that the average value will decrease until the average value no longer decreases and begins to increase, indicating that the gain coefficient of the second conditioning circuit has been adjusted, and the average value of the spectrum amplitude of the noise component frequency band is the smallest. If the average value decreases, it means that the disturbance direction is correct. At this time, continue to increase or decrease the gain coefficient of the second conditioning circuit. It can be expected that the average value will decrease. Until the average value no longer decreases and begins to increase, it means that the gain coefficient of the second conditioning circuit has been adjusted. At this time, the average value of the spectrum amplitude of the noise component frequency band is the smallest.

[0068] In the first embodiment and the second embodiment, the sampling coefficient ratio of the current sensing device on the positive and negative cables is adjusted to achieve the best noise suppression effect. In the first embodiment, the sampling coefficient ratio is adjusted by adjusting the resistance value of the sampling resistor, and in the second embodiment, the sampling coefficient ratio is adjusted by adjusting the gain of the conditioning circuit.

[0069] In addition to the above hardware method for adjusting the gain ratio, the gain ratio may also be adjusted by software, as detailed in Example 3.

[0070] Embodiment three:

[0071] Reference Figure 8 In this embodiment, the sampling circuits of the positive and negative cables, i.e., the current sensing devices, are completely independent and transmit the sampled signals to the controller respectively.

[0072] The first current sensing device may specifically include a first current transformer CT1 and a first sampling resistor R1. The first current transformer CT1 is connected to the positive cable, the first sampling resistor R1 has a fixed resistance value, the first sampling resistor R1 is connected to the first current transformer CT1, and the controller is connected to the first sampling resistor R1. Specifically, the primary coil of the first current transformer CT1 is wound around the positive cable, one end of the secondary coil of the first current transformer CT1 is grounded and connected to one end of the first sampling resistor R1, and the other end of the secondary coil of the first current transformer CT1 is connected to the other end of the first sampling resistor R1 and connected to the first input end of the processor. The first current transformer CT1 is used to isolate and sample the AFCI signal transmitted on the positive cable, remove the DC component therein, and obtain a first current signal; the first sampling resistor R1 is used to convert the first current signal sampled by the first current transformer CT1 into a first voltage signal and transmit it to the processor.

[0073] The second current sensing device may specifically include a second current transformer CT2 and a second sampling resistor R2. The second current transformer CT2 is connected to the negative cable, the second sampling resistor R2 has a fixed resistance value, the second sampling resistor R2 is connected to the second current transformer CT2, the second conditioning circuit is connected to the second sampling resistor R2, and the controller is connected to the second conditioning circuit. Specifically, the primary coil of the second current transformer CT2 is wound around the negative cable, one end of the secondary coil of the second current transformer CT2 is grounded and connected to one end of the second sampling resistor R2, and the other end of the secondary coil of the second current transformer CT2 is connected to the other end of the second sampling resistor R2 and connected to the second input end of the processor. The second current transformer CT2 is used to isolate and sample the AFCI signal transmitted on the negative cable, remove the DC component therein, and obtain a second current signal; the second sampling resistor R2 is used to convert the second current signal sampled by the second current transformer CT2 into a second voltage signal and transmit it to the processor.

[0074] Reference Fig. 9In this embodiment, the first current sensing device may further include a first conditioning circuit disposed between the other end of the secondary coil of the first current transformer and the controller, the first conditioning circuit being used to filter and gain a fixed ratio of the first voltage signal to eliminate other frequency interference. The second current sensing device may further include a second conditioning circuit disposed between the other end of the secondary coil of the second current transformer and the controller, the second conditioning circuit being used to filter and gain a fixed ratio of the second voltage signal to eliminate other frequency interference.

[0075] In this embodiment, the controller is used to convert the first voltage signal and the second voltage signal from analog signals to digital signals respectively, and then calculate the average value of the spectrum amplitude of the noise component frequency band for the first voltage signal and the second voltage signal respectively, and set the average value corresponding to the first voltage signal as A + , the average value corresponding to the second voltage signal is A - , we can directly get the proportionality coefficient K = A of the two average values + / A - , then the controller adjusts the gain ratio between the first voltage signal and the second voltage signal through software, and can obtain the current signal S=S after suppressing the noise signal. + -K*S - ; Among them, S + is the current signal of the positive cable sampled by the first current transformer CT1, S - It is the current signal of the negative cable sampled by the second current transformer CT2.

[0076] The above-mentioned power converter provided in the present application sets independent sampling circuits, i.e., current sensing devices, for the positive and negative cables in the DC arc detection device, so that the gain ratio of the positive and negative cable sampling signals can be independently adjusted for the working condition of asymmetric positive and negative cable loops, thereby achieving the best differential mode signal suppression effect, minimizing the interference of AC current to ground on DC arc detection, and reducing the false alarm probability of DC arc detection.

[0077] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A power converter, characterized in that: include: Power conversion circuit and DC arc detection device; The power conversion circuit has a DC port for connecting positive and negative cables; The DC arc detection device comprises: a first current sensing device, a second current sensing device and a controller; the first current sensing device is used to connect the positive cable, the second current sensing device is used to connect the negative cable, and the first current sensing device and the second current sensing device are connected to the controller respectively; The first current sensing device is used to sense the current change of the positive cable and output a first voltage signal; The second current sensing device is used to sense the current change of the negative cable and output a second voltage signal; The controller is used to adjust a gain ratio between the first voltage signal and the second voltage signal.

2. The power converter according to claim 1, characterized in that The DC arc detection device further includes: a processor; the first current sensing device and the second current sensing device are respectively connected to the processor, and the processor is connected to the controller; The processor is used to combine the first voltage signal and the second voltage signal and output a third voltage signal; The controller is used to adjust a gain ratio between the first voltage signal and the second voltage signal according to the third voltage signal.

3. The power converter according to claim 2, characterized in that: The first current sensing device includes a first current transformer and a first sampling resistor, the primary coil of the first current transformer is wound around the positive cable, one end of the secondary coil of the first current transformer is grounded and connected to one end of the first sampling resistor, and the other end of the secondary coil of the first current transformer is connected to the other end of the first sampling resistor and connected to the first input end of the processor; The second current sensing device includes a second current transformer and a second sampling resistor, the primary coil of the second current transformer is wound around the negative cable, one end of the secondary coil of the second current transformer is grounded and connected to one end of the second sampling resistor, and the other end of the secondary coil of the second current transformer is connected to the other end of the second sampling resistor and connected to the second input end of the processor; The controller is used to adjust the resistance value of the first sampling resistor according to the third voltage signal, and the second sampling resistor has a fixed resistance value; or, the controller is used to adjust the resistance value of the second sampling resistor according to the third voltage signal, and the first sampling resistor has a fixed resistance value; or, the controller is used to adjust the resistance value of the first sampling resistor and the resistance value of the second sampling resistor according to the third voltage signal.

4. The power converter according to claim 3, characterized in that: The DC arc detection device further includes: a conditioning circuit, wherein the conditioning circuit is connected between the processor and the controller; The conditioning circuit is used for filtering the third voltage signal.

5. The power converter according to claim 2, characterized in that: The first current sensing device includes a first current transformer and a first conditioning circuit, the primary coil of the first current transformer is wound around the positive cable, one end of the secondary coil of the first current transformer is grounded, the other end of the secondary coil of the first current transformer is connected to the first conditioning circuit, the first conditioning circuit is connected to the processor, and the first conditioning circuit is used to filter and gain the first voltage signal; The second current sensing device includes a second current transformer and a second conditioning circuit, the primary coil of the second current transformer is wound around the negative cable, one end of the secondary coil of the second current transformer is grounded, the other end of the secondary coil of the second current transformer is connected to the second conditioning circuit, the second conditioning circuit is connected to the processor, and the second conditioning circuit is used to filter and gain the second voltage signal; The controller is used to adjust the gain coefficient of the first conditioning circuit according to the third voltage signal, and the second conditioning circuit has a fixed gain coefficient; or, the controller is used to adjust the gain coefficient of the second conditioning circuit according to the third voltage signal, and the first conditioning circuit has a fixed gain coefficient; or, the controller is used to adjust the gain coefficient of the first conditioning circuit and the gain coefficient of the second conditioning circuit according to the third voltage signal.

6. The power converter according to claim 5, characterized in that The first current sensing device further includes a first sampling resistor, and the first sampling resistor is connected in series with the secondary coil of the first current transformer; The second current sensing device further includes a second sampling resistor, and the second sampling resistor is connected in series with the secondary coil of the second current transformer; The first sampling resistor and the second sampling resistor have fixed resistance values.

7. The power converter according to any one of claims 3 to 6, characterized in that: The winding direction of the positive cable on the first current transformer is opposite to the winding direction of the negative cable on the second current transformer, and the processor is an adding circuit.

8. The power converter according to any one of claims 3 to 6, characterized in that: The winding direction of the positive cable on the first current transformer is the same as the winding direction of the negative cable on the second current transformer, and the processor is a subtraction circuit.

9. The power converter according to claim 1, characterized in that: The first current sensing device includes a first current transformer and a first sampling resistor, the primary coil of the first current transformer is wound around the positive cable, one end of the secondary coil of the first current transformer is grounded, and the other end of the secondary coil of the first current transformer is connected to the controller; The second current sensing device includes a second current transformer and a second sampling resistor, the primary coil of the second current transformer is wound around the negative cable, one end of the secondary coil of the second current transformer is grounded, and the other end of the secondary coil of the second current transformer is connected to the controller; The first sampling resistor and the second sampling resistor have fixed resistance values; The controller is used to adjust a gain ratio between the first voltage signal and the second voltage signal.

10. The power converter according to claim 9, characterized in that: The first current sensing device further includes a first conditioning circuit, the first conditioning circuit being connected between the other end of the secondary coil of the first current transformer and the controller, the first conditioning circuit being used for filtering and fixing a proportional gain of the first voltage signal; The second current sensing device also includes a second conditioning circuit, which is connected between the other end of the secondary coil of the second current transformer and the controller, and is used for filtering and fixing the proportional gain of the second voltage signal.

11. The power converter according to any one of claims 1 to 10, characterized in that: The power conversion circuit is an inverter circuit, and the input side of the inverter circuit has the DC port; or, the power conversion circuit is a DC-to-DC circuit, and the input side and output side of the DC-to-DC circuit have the DC port; or, the power conversion circuit is a rectifier circuit, and the output side of the rectifier circuit has the DC port.

Images