Direct current component detection method and apparatus, direct current component suppression method and apparatus, and power converter

Abstract

A direct current component detection method and apparatus, a direct current component suppression method and apparatus, and a power converter. The direct current component detection method is applied to a power converter. The power converter comprises a transformer and, both connected to the transformer, a primary side circuit and a secondary side circuit. The method comprises: measuring a port voltage of the primary side circuit or secondary side circuit of the power converter to obtain a measurement signal, wherein the port voltage is the voltage of the port of the primary side circuit or secondary side circuit connected to the transformer; and, on the basis of the measurement signal, determining whether the power converter has a direct current component.

Description

DC component detection method, suppression method, device and power converter

[0001] Related applications

[0002] This application claims priority to Chinese patent application number 202311154887.5, filed on September 7, 2023, entitled “DC component detection method, suppression method, device and power converter,” the entire text of which is hereby incorporated by reference. Technical Field

[0003] The present application relates to the field of power electronics technology, and in particular to a DC component detection method, suppression method, device, and power converter. Background Art

[0004] A power converter generally includes switching devices and magnetic elements for power conversion, such as a DC (Direct Current)-DC converter and a DC-AC (Alternating Current) converter, wherein the magnetic elements generally include a transformer and an inductor. When the power converter is working, due to problems such as inconsistent device parameters, parasitic parameters, and drive module delay, the current flowing through the transformer may have a DC component. The DC component can cause the transformer core to be magnetized and thus increase the loss. When the DC component reaches a certain level, it may even cause the core to saturate and damage the circuit. Therefore, in the related art, the influence of DC current is often avoided by adding a series capacitor for isolating DC. However, adding a DC blocking capacitor is a passive way to prevent DC components, and it is impossible to achieve active detection of DC components. In addition, the DC blocking capacitor has the risk of overheating during use and significantly increases the cost and volume of the system.

[0005] Summary of the Invention

[0006] According to various embodiments of the present application, a DC component detection method, a DC component suppression method, a device, and a power converter are provided.

[0007] In a first aspect, the present application provides a method for detecting a DC component. The method is applied to a power converter, wherein the power converter includes a transformer, a primary circuit and a secondary circuit respectively connected to the transformer, and the method includes:

[0008] Detecting a port voltage of a primary circuit or a secondary circuit of the power converter to obtain a detection signal, wherein the port voltage is a voltage of a port where the primary circuit or the secondary circuit is connected to the transformer;

[0009] Based on the detection signal, it is determined whether a DC component exists in the power converter.

[0010] In some embodiments, detecting the port voltage of the primary circuit or the secondary circuit of the power converter to obtain a detection signal includes:

[0011] Sampling the port voltage to obtain a sampling signal;

[0012] The sampled signal is compared with a preset reference signal to obtain a detection signal.

[0013] In some embodiments, sampling the port voltage to obtain a sampling signal includes:

[0014] Performing differential sampling on the port voltage to obtain a differential signal;

[0015] A DC bias is applied to the differential signal to obtain a sampling signal.

[0016] In some embodiments, determining whether a DC component exists in the power converter based on the detection signal includes:

[0017] If the duty cycle of the detection signal satisfies a preset duty cycle determination condition, it is determined that no DC component exists in the power converter; otherwise, a DC component exists.

[0018] In some embodiments, the duty cycle determination condition includes:

[0019] The duty cycle of the detection signal is equal to a preset duty cycle; or

[0020] The duty cycle of the detection signal including the positive duty cycle information of the port voltage is equal to the duty cycle of the detection signal including the negative duty cycle information of the port voltage.

[0021] In a second aspect, the present application provides a method for suppressing a DC component, the method comprising:

[0022] Based on the DC component detection method described in the first aspect, detecting whether there is a DC component in the power converter;

[0023] When a DC component exists, the DC component is suppressed based on the duty cycle of the detection signal.

[0024] In some embodiments, suppressing the DC component based on the duty cycle of the detection signal includes:

[0025] When the duty cycle of the detection signal is within a preset duty cycle threshold range, determining a driving duty cycle of the corresponding primary circuit or secondary circuit based on the duty cycle of the detection signal and a reference duty cycle;

[0026] A corresponding driving signal is generated based on the driving duty cycle, and the corresponding primary circuit or secondary circuit is driven to suppress the DC component.

[0027] In some embodiments, the reference duty cycle is a set value, or is obtained based on a positive duty cycle and a negative duty cycle of the port voltage.

[0028] In some embodiments, suppressing the DC component based on the duty cycle of the detection signal further includes:

[0029] When the duty cycle of the detection signal is outside the duty cycle threshold range, the power converter is controlled to stop operating.

[0030] In a third aspect, the present application provides a DC component detection device, which is applied to a power converter, the power converter including a transformer, a primary circuit and a secondary circuit respectively connected to the transformer, and the device including:

[0031] a detection circuit, configured to detect a port voltage of a primary circuit or a secondary circuit of the power converter to obtain a detection signal, wherein the port voltage is a voltage at a port where the primary circuit or the secondary circuit is connected to the transformer;

[0032] The control circuit is connected to the detection circuit and is used to determine whether a DC component exists in the power converter based on the detection signal.

[0033] In some embodiments, the detection circuit includes:

[0034] A sampling circuit, used for sampling the port voltage to obtain a sampling signal;

[0035] The comparison circuit is connected to the sampling circuit and is used to compare the sampling signal with a preset reference signal to obtain a detection signal.

[0036] In some embodiments, the sampling circuit includes:

[0037] A differential sampling circuit, configured to perform differential sampling on the port voltage to obtain a differential signal;

[0038] A DC bias circuit is connected to the differential sampling circuit and is used to apply a DC bias to the differential signal to obtain a sampling signal.

[0039] In some embodiments, the sampling circuit further includes:

[0040] The isolation transmission circuit is connected between the DC bias circuit and the comparison circuit, and is used for isolating and transmitting the sampling signal to the comparison circuit.

[0041] In some embodiments, the control circuit is used to determine that there is no DC component in the power converter when the duty cycle of the detection signal meets a preset duty cycle determination condition, otherwise determine that there is a DC component in the power converter.

[0042] In some embodiments, the duty cycle determination condition includes:

[0043] The duty cycle of the detection signal is equal to a preset duty cycle; or

[0044] The duty cycle of the detection signal including the positive duty cycle information of the port voltage is equal to the duty cycle of the detection signal including the negative duty cycle information of the port voltage.

[0045] In a fourth aspect, the present application provides a DC component suppression device, which is applied to a power converter, the power converter including a transformer, a primary circuit and a secondary circuit respectively connected to the transformer, and the device including:

[0046] As described in the DC component detection device of the third aspect, when a DC component exists, the control circuit of the DC component detection device suppresses the DC component based on the duty cycle of the detection signal.

[0047] In some embodiments, the DC component suppression device further includes a drive circuit connected to the control circuit.

[0048] When the duty cycle of the detection signal is outside a preset duty cycle threshold range, the control circuit controls the power converter to stop operating; and / or

[0049] When the duty cycle of the detection signal is within the duty cycle threshold range, the control circuit obtains a driving duty cycle based on the duty cycle of the detection signal, and the driving circuit generates a corresponding driving signal based on the driving duty cycle to suppress the DC component.

[0050] In a fifth aspect, the present application provides a power converter, which includes: a transformer, a primary circuit and a secondary circuit respectively connected to the transformer, and a DC component detection device as described in the third aspect.

[0051] In some embodiments, the primary circuit or the secondary circuit is any one of a full-bridge inverter circuit, a half-bridge inverter circuit, a full-bridge rectifier circuit, a half-bridge rectifier circuit, a multi-level inverter circuit, and a cycloconversion circuit.

[0052] In some embodiments, the power converter is a DC-DC converter or a DC-AC converter.

[0053] The details of one or more embodiments of the present application are set forth in the following drawings and description to make other features, objects, and advantages of the present application more readily apparent. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the following briefly introduces the drawings required for use in the embodiments or related technical descriptions. Obviously, the drawings described below are merely embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the disclosed drawings without any creative work.

[0055] FIG1 is a flow chart of a DC component detection method according to some embodiments of the present application.

[0056] FIG2 is a schematic diagram of a circuit topology of a dual-active bridge converter according to some embodiments of the present application.

[0057] FIG3 is a schematic diagram of a circuit topology of a DC-AC converter according to some embodiments of the present application.

[0058] FIG4 is a schematic diagram of a circuit topology of a DC-AC converter according to some other embodiments of the present application.

[0059] FIG5 is a topological diagram of a half-bridge circuit and a multi-level inverter circuit according to some embodiments of the present application.

[0060] FIG6 is a flow chart of detection signal acquisition in some embodiments of the present application.

[0061] FIG7 is a flow chart of sampling signal acquisition in some embodiments of the present application.

[0062] FIG8 is a flow chart of a DC component suppression method according to some embodiments of the present application.

[0063] FIG9 is a flow chart of suppressing a DC component based on a duty cycle of a detection signal according to some embodiments of the present application.

[0064] FIG10 is a schematic structural diagram of a DC component detection device according to some specific embodiments of the present application.

[0065] FIG11 is a structural block diagram of a DC component suppression device according to some embodiments of the present application.

[0066] FIG12 is a waveform diagram of a DC component suppression process according to some embodiments of the present application. DETAILED DESCRIPTION

[0067] In order to more clearly understand the purpose, technical solutions and advantages of this application, the present application is described and illustrated below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0068] Unless otherwise defined, the technical terms or scientific terms involved in this application should have the general meaning understood by people with ordinary skills in the technical field to which this application belongs. The words "one", "an", "a", "the", "these" and the like in this application do not indicate quantitative restrictions, and they can be singular or plural. The terms "include", "comprise", "have" and any variants thereof involved in this application are intended to cover non-exclusive inclusions; for example, a process, method and system, product or device comprising a series of steps or modules (units) is not limited to the listed steps or modules (units), but may include unlisted steps or modules (units), or may include other steps or modules (units) inherent to these processes, methods, products or devices. The words "connect", "connected", "coupled" and the like involved in this application are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The "plurality" involved in this application refers to two or more. "And / or" describes the relationship between related objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A exists alone, A and B exist simultaneously, and B exists alone. Generally, the character " / " indicates that the related objects are in an "or" relationship. The terms "first," "second," "third," etc. used in this application are only used to distinguish similar objects and do not represent a specific ordering of the objects.

[0069] The present application provides a method for detecting a DC component. The method is applied to a power converter, wherein the power converter includes a transformer and a primary circuit and a secondary circuit respectively connected to the transformer. FIG1 is a flow chart of the DC component detection method according to some embodiments of the present application. As shown in FIG1 , the method includes the following steps:

[0070] Step S101 : detecting a port voltage of a primary circuit or a secondary circuit of a power converter to obtain a detection signal, wherein the port voltage is a voltage of a port where the primary circuit or the secondary circuit is connected to a transformer.

[0071] The primary circuit and the secondary circuit in at least one embodiment of the present application may be different types of power conversion circuits. In some embodiments, the port voltage is the voltage of the port where the primary circuit or the secondary circuit is connected to the transformer, and the power converter may be a dual-active bridge converter for DC conversion. For example, FIG2 is a schematic diagram of the circuit topology of a dual-active bridge converter in some embodiments of the present application. As shown in FIG2 , the dual-active bridge converter includes a transformer T and a resonant network 23 connected to the transformer T, as well as a primary circuit 21 located on the primary side of the transformer T and a secondary circuit 24 located on the secondary side of the transformer T. The primary circuit 21 and the secondary circuit 24 may be full-bridge circuits, the primary circuit 21 includes power switches S1, S2, S3, and S4, the secondary circuit 24 includes power switches S5, S6, S7, and S8, and the resonant network 23 includes an inductor L1.

[0072] Furthermore, the dual active bridge converter further includes a capacitor C1 and a capacitor C2.

[0073] The dual-active bridge converter can perform bidirectional power conversion. If the conversion direction is from left to right, the DC voltage V1 is inverted into an AC voltage through the primary circuit 21. After the AC voltage is adjusted by the transformer T, the adjusted AC voltage is rectified into a DC voltage V2 through the secondary circuit 24. If the power conversion direction is from right to left, the DC voltage V2 is inverted into an AC voltage through the secondary circuit 24. After the AC voltage is adjusted by the transformer T, the adjusted AC voltage is rectified into a DC voltage V1 through the primary circuit 21. Points a and b are the midpoints of the bridge arms of the primary circuit 21, and the voltage V between points a and b is ab is the port voltage of the primary circuit 21. Points c and d are the midpoints of the bridge arm of the secondary circuit 24, respectively. The voltage V cd The port voltage V of the secondary circuit 24 can be selected according to actual needs. ab and / or the terminal voltage V of the secondary circuit 24 cd Perform detection and obtain a detection signal.

[0074] In some specific embodiments, the power converter can also be a two-stage DC-AC power converter, in which the dual-active bridge converter in the aforementioned embodiment serves as the first stage of the DC-AC power converter to perform DC conversion, and the DC-AC circuit serves as the second stage of the DC-AC power converter to perform AC conversion.

[0075] In some other embodiments, the power converter can be a single-stage DC-AC converter. In this case, the primary circuit or the secondary circuit can also be a cycloconversion circuit for AC-AC conversion. Figure 3 is a circuit topology diagram of the DC-AC converter in some embodiments of the present application. As shown in Figure 3, the DC-AC converter includes a primary circuit 31, a transformer T, a resonant network 33, a secondary circuit 34 and a filter circuit 35. Among them, the primary circuit 31 is a full-bridge circuit, including power switch tubes Q1H, Q1L, Q2H, Q2L; the resonant network 33 includes an inductor Lr; the secondary circuit 34 is a full-bridge cycloconversion circuit, including power switch tubes Q3~Q10; the filter circuit 35 includes a capacitor C f and inductor L f ; The DC-AC converter also includes a capacitor Cin.

[0076] DC voltage V dc The primary circuit 31 converts the AC voltage into an AC voltage, the transformer T adjusts the AC voltage, and the secondary circuit 34 adjusts the frequency of the AC voltage. Finally, the filter circuit 35 filters the AC voltage and outputs the AC voltage V g In the primary circuit 31 and the secondary circuit 34 shown in FIG3 , both the port voltage can be detected. In the figure, point a and point b are the midpoints of the bridge arm of the primary circuit 31, and the voltage V between points a and b is ab is the port voltage of the primary circuit 31. Points c and d are the midpoints of the bridge arm of the secondary circuit 34, respectively. The voltage V cd The port voltage V of the secondary circuit 34 can be selected according to actual needs. ab and / or the terminal voltage V of the secondary circuit 34 cd Perform detection and obtain a detection signal.

[0077] Furthermore, FIG4 is a schematic diagram of the circuit topology of a DC-AC converter according to another embodiment of the present invention. As shown in FIG4, the DC-AC converter includes a primary circuit 41, a transformer T, a resonant network 43, a secondary circuit 44, a filter circuit 45, and a capacitor Cin. Unlike the circuit topology of FIG3, the secondary circuit 44 is a half-bridge cycloconverter circuit, and the resonant network 43 further includes a resonant capacitor C r , which can isolate DC, so in this embodiment, there is no need to detect the port voltage of the secondary circuit 44.

[0078] Those skilled in the art will appreciate that the structures shown in Figures 2, 3, and 4 are for illustration only and do not limit the structures of the dual-active bridge converter of Figure 2 or the DC-AC converters of Figures 3 and 4. For example, the resonant network 33 of Figure 3 can be disposed on the primary side of the transformer 32, and the circuit form of the resonant network 33 can also be various structures such as LC or CLLC.

[0079] For example, in the dual-active bridge converter in FIG2 , the primary circuit 21 or the secondary circuit 24 can also be replaced by a half-bridge circuit or a multi-level inverter circuit as shown in FIG5 . In the half-bridge circuit shown in FIG5A , the voltage V between points a and b is ab is the port voltage of the half-bridge circuit. In the multi-level circuit shown in FIG5B , the voltage V between points c and d is cd is the port voltage of the multi-level inverter circuit.

[0080] To determine whether a DC component exists in the transformer's current, detection can be performed on either the primary or secondary side of the transformer. Therefore, the voltage at the terminals of the primary and / or secondary circuits can be detected, and the resulting detection signal can be a square wave signal or other type of signal.

[0081] Step S102 : determining whether a DC component exists in the power converter based on the detection signal.

[0082] The presence of a DC component in the power converter can be determined based on the characteristic parameters extracted from the detection signal; or the presence of a DC component in the power converter can be determined based on the comparison result by comparing the detection signal with a reference signal.

[0083] Through the above steps S101 to S102, the port voltage of the primary circuit or the secondary circuit of the power converter is detected to obtain a detection signal; based on the detection signal, it is determined whether a DC component exists in the power converter, and a DC component detection result is obtained, thereby realizing active detection of whether a DC component exists in the power converter, and the detection method is simple and low-cost.

[0084] In some embodiments, FIG6 is a flow chart of detection signal acquisition in some embodiments of the present application. As shown in FIG6 , the flow includes the following steps:

[0085] Step S501: sampling the port voltage to obtain a sampling signal.

[0086] According to the circuit topology of the primary circuit and the secondary circuit of the power converter, the port voltage of the primary circuit and / or the secondary circuit may be selected for sampling.

[0087] Step S502: Compare the sampled signal with a preset reference signal to obtain a detection signal.

[0088] The reference signal may be a DC level of a preset value. Specifically, a hysteresis comparison may be performed between the sampling signal and the reference signal to obtain a detection signal, which is a square wave signal and includes characteristic parameter information of the port voltage. The characteristic parameters may be, for example, a positive duty cycle of the port voltage (i.e., the ratio of the duration of the positive voltage of the port voltage in a control cycle to the control cycle) and / or a negative duty cycle (i.e., the ratio of the duration of the negative voltage of the port voltage in a control cycle to the control cycle), or the duration of the positive and / or negative value of the port voltage in a control cycle. This application takes the duty cycle of the port voltage as an example for explanation.

[0089] Through the above steps S501 to S502, the port voltage is sampled to obtain a sampling signal; the sampling signal is compared with a preset reference signal through hysteresis to obtain a detection signal, thereby eliminating the influence caused by the port voltage being easily susceptible to interference near 0V, improving the quality and detection accuracy of the detection signal, and the detection signal includes the duration information of the port voltage being positive and / or negative within a control cycle, or includes the positive duty cycle and / or negative duty cycle of the port voltage, and then determines whether a DC component exists based on the duration or duty cycle. Through a simple and quick detection method, it is possible to determine whether the power converter has a DC component, thereby improving the detection efficiency of the DC component and reducing the detection cost.

[0090] In some embodiments, FIG7 is a flow chart of sampling signal acquisition in some embodiments of the present application. As shown in FIG7 , the flow includes the following steps:

[0091] Step S601: differentially sample the port voltage to obtain a differential signal.

[0092] The port voltage can be differentially sampled and its amplitude can be reduced by a preset sampling ratio to obtain a differential signal. For example, the sampling ratio can be calculated in advance based on the input port voltage amplitude and the output voltage range of the differential sampling.

[0093] Step S602: applying a DC bias to the differential signal to obtain a sampling signal.

[0094] Since the port voltage is near 0V and is easily disturbed, a DC bias can be applied to facilitate hysteresis comparison so that the voltage values ​​of the sampled signals are all greater than or equal to 0. The DC bias value can be slightly larger than the range of the differential signal.

[0095] Furthermore, when a DC bias is applied to the sampling signal, the reference signal can be equal to the DC bias to ensure the accuracy of the duration of positive and negative port voltage values ​​included in the detection signal. For example, if the applied DC bias is 2.5V, the reference signal is also equal to 2.5V.

[0096] Through the above steps S601 to S602, a differential signal is obtained by differentially sampling the port voltage; a sampling signal is obtained by applying a DC bias to the differential signal, which facilitates subsequent hysteresis comparison to eliminate the influence of interference near the port voltage 0V.

[0097] Furthermore, in some embodiments, after sampling the port voltage and applying a DC bias to obtain a sampled signal, the sampled signal is isolated and transmitted. Isolated transmission can further improve circuit safety.

[0098] In some embodiments, a specific method for determining whether a power converter has a DC component based on a detection signal is provided. The method includes:

[0099] Based on the duty cycle of the detection signal, it is determined whether a DC component exists in the power converter.

[0100] The duty cycle of the detection signal refers to the proportion of the duration of the detection signal's positive voltage over the entire control period. When a DC component exists in the primary or secondary circuit, it causes the positive and negative duty cycles of the port voltage to be unequal, causing the average port voltage to deviate from 0V. Because the duty cycle of the detection signal and the duty cycle of the port voltage are consistent, the presence of a DC component in the power converter can be determined based on the duty cycle of the detection signal.

[0101] The DC component detection method of at least one embodiment of the present application determines whether a DC component exists in a power converter by detecting the port voltage to obtain the duty cycle of the detection signal. The detection method is simple and highly practical.

[0102] Specifically, when the duty cycle of the detection signal meets a preset duty cycle determination condition, it is determined that no DC component exists in the power converter; otherwise, a DC component exists.

[0103] In some embodiments, for the power converter shown in Figures 2 and 3, when the power converter adopts single-phase shift control, the duty cycle determination condition can be that the duty cycle of the detection signal is equal to the preset duty cycle; since the positive duty cycle and negative duty cycle of the port voltage in the single-phase shift control are equal and both are 50% (without considering the dead zone), the duty cycle of the detection signal is equal to either the positive duty cycle or the negative duty cycle of the port voltage. When the duty cycle of the detection signal is equal to the preset duty cycle, it is determined that there is no DC component in the power converter; when the duty cycle of the detection signal is not equal to the preset duty cycle, it is determined that there is a DC component in the power converter. The preset duty cycle is, for example, 50% or other preset values.

[0104] Alternatively, a first detection signal including positive duty cycle information of the port voltage and a second detection signal including negative duty cycle information of the port voltage can be obtained by detecting the port voltage. In some embodiments, the duty cycle of the first detection signal is equal to the positive duty cycle of the port voltage, and the duty cycle of the second detection signal is equal to the negative duty cycle of the port voltage. Therefore, the duty cycle determination condition can be that the duty cycle of the first detection signal and the duty cycle of the second detection signal are equal. When the duty cycle of the first detection signal and the duty cycle of the second detection signal are equal, it is determined that there is no DC component in the power converter; when the duty cycle of the first detection signal and the duty cycle of the second detection signal are not equal, it is determined that there is a DC component in the power converter.

[0105] When the port voltage V cd When sampling, the preset duty cycle changes within each control cycle and can be set according to the control requirements.

[0106] For power converters that do not use phase-shift control, the method is the same as single-phase-shift control and will not be described in detail here.

[0107] In the case of dual phase shift control, that is, when there is phase shift inside the primary circuit or the secondary circuit, the positive duty cycle of the port voltage is equal to the negative duty cycle. Since there is phase shift inside the primary circuit or the secondary circuit, a first detection signal including positive duty cycle information of the port voltage and a second detection signal including negative duty cycle information of the port voltage can be obtained by detecting the port voltage. In some embodiments, the duty cycle of the first detection signal is equal to the positive duty cycle of the port voltage, and the duty cycle of the second detection signal is equal to the negative duty cycle of the port voltage. Therefore, the duty cycle determination condition can be that the duty cycle of the first detection signal and the duty cycle of the second detection signal are equal. When the duty cycle of the first detection signal and the duty cycle of the second detection signal are equal, it is determined that there is no DC component in the power converter; when the duty cycle of the first detection signal and the duty cycle of the second detection signal are not equal, it is determined that there is a DC component in the power converter.

[0108] The DC component detection method of at least one embodiment of the present application determines whether the duty cycle of the detection signal meets a preset duty cycle determination condition, and determines that no DC component exists in the power converter when the duty cycle determination condition is met. Specific determination conditions for DC component detection in different control modes are provided, thereby expanding the application scope and practicality of the present method.

[0109] In some embodiments, a DC component suppression method is further provided. FIG8 is a flow chart of the DC component suppression method according to some embodiments of the present application. As shown in FIG8 , the flow chart includes the following steps:

[0110] Step S701 : Based on the DC component detection method in the above embodiment, detecting whether there is a DC component in the power converter.

[0111] Step S702 : When a DC component exists, suppress the DC component based on the duty cycle of the detection signal.

[0112] When a DC component exists in the power converter, a driving signal for driving the primary circuit or the secondary circuit of the power converter can be generated according to the duty cycle of the detection signal, thereby suppressing the DC component.

[0113] Through the above steps S701 to S702, the DC component detection method based on the above embodiment is used to detect whether a DC component exists in the power converter, thereby realizing the DC component detection function; when the DC component is detected to exist, the DC component is suppressed based on the duty cycle of the detection signal, and the DC component existing in the power converter is eliminated without adding a DC blocking capacitor, thereby reducing the volume and cost of the power converter.

[0114] FIG9 is a flow chart of suppressing a DC component based on a duty cycle of a detection signal according to some embodiments of the present application. As shown in FIG9 , the flow includes the following steps:

[0115] Step S801 , determining whether the duty cycle of the detection signal is within a preset duty cycle threshold range.

[0116] Step S802 : When the duty cycle of the detection signal is within a preset duty cycle threshold range, the driving duty cycle of the corresponding primary circuit or secondary circuit is determined based on the duty cycle of the detection signal and a reference duty cycle.

[0117] In at least some embodiments of the present application, whether the DC component present in the power converter is too large can be determined by determining whether the duty cycle of the detection signal is within a preset duty cycle threshold range. The duty cycle threshold range can include a duty cycle lower limit value and a duty cycle upper limit value, and the duty cycle upper limit value is greater than the duty cycle lower limit value.

[0118] When the duty cycle of the detection signal is greater than the lower limit value of the duty cycle and less than the upper limit value of the duty cycle, it can be determined that the DC component is within a safe range, and there is no operating safety risk of the power converter in a short period of time. A drive signal for driving the corresponding primary circuit or secondary circuit can be generated according to the duty cycle of the detection signal to suppress the DC component.

[0119] Specifically, the duty cycle of the detection signal may be subtracted from the reference duty cycle, and the driving duty cycle of the current power converter may be determined through a PI control loop.

[0120] Specifically, in the case where the power converter adopts single phase shift control or does not adopt phase shift control, the reference duty cycle can be a set value, such as 50% (without considering the dead zone), or it can be calculated based on the positive duty cycle and negative duty cycle of the detected port voltage, for example, based on the duty cycle of the first detection signal including the positive duty cycle information of the port voltage and the duty cycle of the second detection signal including the negative duty cycle information of the port voltage, in this case, the duty cycle of the first detection signal is the positive duty cycle of the detected port voltage, and the duty cycle of the second detection signal is the negative duty cycle of the detected port voltage; in the case where the power converter adopts dual phase shift control, the reference duty cycle can also be calculated based on the positive duty cycle and negative duty cycle of the detected port voltage. For example, the reference duty cycle can be equal to the average of the positive duty cycle and negative duty cycle of the detected port voltage. Assuming that the positive duty cycle of the detected port voltage is 40% and the negative duty cycle of the detected port voltage is 30%, the reference duty cycle can be set to 35%.

[0121] Specifically, in the case where the primary circuit or the secondary circuit is a cycloconversion circuit, the reference duty cycle changes in each control cycle and can be calculated or set according to control requirements.

[0122] Step S803 : generating a corresponding driving signal based on the driving duty cycle, and driving the corresponding primary circuit or secondary circuit to suppress the DC component.

[0123] The detection signal and the drive duty cycle have a same-side correspondence on the power converter. For example, for the dual-active bridge converter shown in Figure 2, if the detection signal is obtained by detecting the port voltage of the primary circuit 21, the duty cycle of the detection signal can be used to determine the drive duty cycle of the primary circuit 21 to suppress the DC component of the primary circuit 21; if the detection signal is obtained by detecting the port voltage of the secondary circuit 24, the duty cycle of the detection signal can be used to determine the drive duty cycle of the secondary circuit 24 to suppress the DC component of the secondary side. A corresponding drive signal is generated based on the drive duty cycle, and the drive signal is used to control the on and off of the power switch tube in the primary circuit or the secondary circuit, thereby suppressing the DC component.

[0124] Through the above steps S801 to S803, when the duty cycle of the detection signal is within the preset duty cycle threshold range, the driving duty cycle of the primary circuit or the secondary circuit is determined based on the duty cycle of the detection signal and the reference duty cycle. That is, first, it is judged whether the power converter has a safety risk based on the duty cycle of the detection signal. When it is determined that there is no operational safety risk in a short period of time, the driving duty cycle corresponding to the DC component is obtained by calculation, and a corresponding driving signal is generated based on the driving duty cycle to drive the power switch tube in the primary circuit or the secondary circuit to be turned on and off to suppress the DC component. When there is no safety risk to the power converter, the DC component in the power converter is gradually suppressed and eliminated, the loss of the power converter is reduced, and the efficiency of power conversion is improved.

[0125] In some embodiments, a method for protecting a power converter when the duty cycle of a detection signal is outside a duty cycle threshold range is also provided. The method comprises:

[0126] When the duty cycle of the detection signal is outside the duty cycle threshold range, the power converter is controlled to stop working immediately.

[0127] If the duty cycle of the detection signal is less than the lower limit or greater than the upper limit, the DC component is considered excessive, and the power converter presents safety risks, including core saturation and transformer overheating. In this case, the power converter should be immediately stopped to avoid safety accidents.

[0128] The power converter protection method of at least one embodiment of the present application avoids the occurrence of safety accidents and improves the operating safety of the power converter by controlling the power converter to stop working when the duty cycle of the detection signal is outside the duty cycle threshold range.

[0129] It should be understood that although the steps in the flowcharts of the various embodiments described above are shown sequentially as indicated by the arrows, these steps are not necessarily executed sequentially in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order restriction on the execution of these steps, and these steps may be executed in other orders.

[0130] The present application also provides a DC component detection device. FIG10 is a schematic structural diagram of a DC component detection device according to some embodiments of the present application. As shown in FIG10 , the device includes:

[0131] The detection circuit 91 is used to detect the port voltage of the primary circuit or the secondary circuit of the power converter to obtain a detection signal, wherein the port voltage is the voltage of the port where the primary circuit or the secondary circuit is connected to the transformer;

[0132] The control circuit 92 is connected to the detection circuit 91 and is used to determine whether a DC component exists in the power converter based on the detection signal.

[0133] Specifically, the detection circuit 91 includes a sampling circuit 910 and a comparison circuit 912. The sampling circuit 910 is used to sample the port voltage to obtain a sampling signal; the comparison circuit 912 is connected to the sampling circuit 910, receives the sampling signal, and compares the sampling signal with a preset reference signal to obtain a detection signal.

[0134] The comparison circuit 912 may be implemented using a hysteresis comparator to perform a hysteresis comparison between the sampled signal and a preset reference signal to obtain a detection signal, thereby reducing the influence of signal interference.

[0135] The control circuit 92 can be implemented as a controller, such as a microcontroller unit (MCU), a central processing unit (CPU), a field programmable gate array (FPGA), or a digital signal processor (DSP). Of course, the specific form of the control circuit 92 is not limited to the above examples.

[0136] In some embodiments, the sampling circuit 910 includes:

[0137] The differential sampling circuit 9102 is used to perform differential sampling on the port voltage to obtain a differential signal;

[0138] a DC bias circuit 9104 connected to the differential sampling circuit 9102 and configured to apply a DC bias to the differential signal to obtain a sampled signal. The DC bias is applied to raise the value of the differential signal so that the sampled signal is greater than 0, facilitating hysteresis comparison by the comparison circuit 912. Optionally, the value of the DC bias is equal to the value of the reference signal.

[0139] In some embodiments, the sampling circuit 910 further includes an isolation transmission circuit 9106 connected between the DC bias circuit and the comparison circuit for isolating and transmitting the sampling signal to the comparison circuit 912 to further improve the safety of the circuit.

[0140] Among them, the differential sampling circuit 9102 can be implemented by devices such as operational amplifiers and resistors; the DC bias circuit 9104 can be implemented by operational amplifiers and DC bias voltage; and the isolated transmission circuit 9106 can be implemented by using an isolation chip, etc.

[0141] The DC component detection device of at least one embodiment of the present application samples the port voltage through a sampling circuit to obtain a sampling signal; and performs a hysteresis comparison between the sampling signal and a preset reference signal through a comparison circuit to obtain a detection signal, thereby eliminating the influence caused by the port voltage being susceptible to interference near 0V, improving the quality and detection accuracy of the detection signal. The detection signal includes information on the duration of the port voltage being positive and / or negative within a control cycle, or includes the positive duty cycle and / or negative duty cycle of the port voltage, and then determines whether a DC component exists based on the duration or duty cycle.

[0142] Specifically, the control circuit 92 receives the detection signal, obtains the duty cycle of the detection signal, and determines whether a DC component exists based on the duty cycle of the detection signal. If the duty cycle of the detection signal satisfies a preset duty cycle determination condition, it is determined that the power converter does not have a DC component; otherwise, it is determined that the power converter has a DC component.

[0143] In some embodiments, the comparison circuit 912 compares the sampling signal with a preset reference signal to generate a detection signal whose duty cycle is equal to the positive duty cycle or negative duty cycle of the port voltage. The duty cycle determination condition may be that the duty cycle of the detection signal is equal to the preset duty cycle.

[0144] In other embodiments, the comparison circuit 912 compares the sampled signal with a preset reference signal to generate a first detection signal including information about the positive duty cycle of the port voltage and a second detection signal including information about the negative duty cycle of the port voltage. In some embodiments, the duty cycle of the first detection signal is equal to the positive duty cycle of the port voltage, and the duty cycle of the second detection signal is equal to the negative duty cycle of the port voltage. The duty cycle determination condition may be that the duty cycle of the first detection signal and the duty cycle of the second detection signal are equal.

[0145] For example, for the dual active bridge converter shown in FIG2 , the detection circuit 91 can detect the port voltage V ab A detection is performed to obtain a detection signal, and the control circuit 92 determines whether a DC component exists based on the detection signal. For example, the control circuit 92 determines whether a DC component exists based on the duty cycle of the detection signal. When the duty cycle of the detection signal is equal to a preset duty cycle, the control circuit 92 determines that a DC component does not exist on that side; when the duty cycle of the detection signal is not equal to the preset duty cycle, the control circuit 92 determines that a DC component exists on that side.

[0146] In summary, the DC component detection device of at least one embodiment of the present application detects the port voltage of the primary circuit or secondary circuit of the power converter via detection circuit 91 to obtain a detection signal; and determines whether a DC component is present in the power converter based on the detection signal via control circuit 92 to obtain a DC component detection result. This implements active detection of the presence of a DC component in the power converter, and the detection method is simple and low-cost. Furthermore, the detection device of at least one embodiment of the present application can be used in power converters with different control modes, expanding its scope of application and increasing its practicality.

[0147] The present application also provides a DC component suppression device. FIG11 is a structural block diagram of the DC component suppression device of some embodiments of the present application. As shown in FIG11 , the DC component suppression device includes a detection circuit 91, a control circuit 92, and a drive circuit 93. The detection circuit 91 is used to detect the port voltage of the primary circuit or the secondary circuit of the power converter to obtain a detection signal; the control circuit 92 is used to determine whether the power converter has a DC component based on the detection signal. When it is determined that the power converter has a DC component, the control circuit 92 calculates the drive duty cycle based on the duty cycle of the detection signal, and the drive circuit 93 generates a corresponding drive signal based on the drive duty cycle to suppress the DC component.

[0148] In at least one embodiment of the present application, the detection of the DC component by the detection circuit 91 and the control circuit 92 can be specifically described in the embodiment of FIG10 . The following only introduces the suppression of the DC component.

[0149] Specifically, when it is determined that a DC component exists in the power converter, when the duty cycle of the detection signal is outside the preset duty cycle threshold range, the control circuit 92 controls the power converter to stop working; when the duty cycle of the detection signal is within the duty cycle threshold range, the control circuit 92 obtains the driving duty cycle based on the duty cycle of the detection signal, and the driving circuit 93 generates a corresponding driving signal based on the driving duty cycle to suppress the DC component.

[0150] For example, for the dual active bridge converter shown in FIG2 , the detection circuit 91 can detect the port voltage V ab Detection is performed to obtain a detection signal. The control circuit 92 determines whether a DC component exists based on the duty cycle of the detection signal. When it is determined that a DC component exists and the duty cycle of the detection signal is within the duty cycle threshold range, the control circuit 92 calculates the drive duty cycle of the primary circuit 21 based on the duty cycle of the detection signal. The drive circuit 93 generates a drive signal for the primary circuit 21 based on the drive duty cycle to suppress the DC component of the primary side.

[0151] Figure 12 is a waveform diagram of the DC component suppression process in some embodiments of the present application. As shown in Figure 12, T is the control period, PWM1 is the drive signal for the switches S1 and S4 of the primary circuit 21, and PWM2 is the drive signal for the switches S2 and S3 of the primary circuit 21.

[0152] At time t1, based on the detection signal, the port voltage V ab If the forward duty cycle of the drive signal is not equal to 50%, it is determined that a DC component exists. The duty cycle of the drive signal is adjusted cycle by cycle according to the DC component suppression method in the above embodiment. After several control cycles T, such as more than ten or even dozens of control cycles T, at time t2, the duty cycle of the drive signal is adjusted to 50% to completely eliminate the DC component. The dotted line represents the duty cycle before DC component suppression, and the solid line represents the duty cycle after DC component suppression.

[0153] In summary, the DC component suppression device of at least one embodiment of the present application determines whether there is a safety risk in the power converter based on the duty cycle of the detection signal through the control circuit. When it is determined that there is no operational safety risk, the control circuit calculates the driving duty cycle corresponding to the DC component, and the driving circuit generates a corresponding driving signal based on the driving duty cycle to drive the power switch tube in the primary circuit or the secondary circuit to be turned on and off to suppress the DC component, reduce the loss of the power converter, and improve the efficiency of power conversion. It also eliminates the DC component in the power converter without adding a DC blocking capacitor, reducing the size and cost of the power converter. The detection device has a simple structure, low cost, and high practicality. When it is determined that there is an operational safety risk, the control circuit controls the power converter to stop working, avoiding the occurrence of safety accidents and improving the operational safety of the power converter.

[0154] In some embodiments, the present application further provides a power converter, which includes a transformer, a primary circuit and a secondary circuit respectively connected to the transformer, and the DC component detection device of the above embodiment.

[0155] Specifically, the primary circuit or the secondary circuit of the power converter can be any one of a full-bridge inverter circuit, a half-bridge inverter circuit, a full-bridge rectifier circuit, a half-bridge rectifier circuit, a multi-level inverter circuit, and a cycloconversion circuit.

[0156] Specifically, the power converter may be a DC-DC converter or a DC-AC converter.

[0157] The power converter of at least one embodiment of the present application realizes power conversion from input to output through a transformer and a primary circuit and a secondary circuit connected to the transformer; a DC component detection device is used to detect whether a DC component exists in the primary circuit or the secondary circuit, and the DC component is suppressed when a DC component exists, thereby reducing the loss of the power converter, eliminating the operational safety risks of the power converter, and improving the efficiency of power conversion.

[0158] In addition, in conjunction with the DC component detection method provided in the above embodiments, this application may also provide a readable storage medium for implementation. The readable storage medium stores a program; when the program is executed by a processor, any of the DC component detection methods in the above embodiments is implemented.

[0159] It should be noted that, for specific examples in this embodiment, reference may be made to the examples described in the above embodiments and optional implementation modes, and will not be repeated in this embodiment.

[0160] It should be understood that the specific embodiments described herein are only used to explain this application and are not used to limit it. Based on the embodiments provided in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0161] Obviously, the accompanying drawings are merely examples or embodiments of the present application. A person skilled in the art can also apply the present application to other similar situations based on these drawings without inventive effort. Furthermore, it is understandable that, although the work involved in this development process may be complex and lengthy, certain design, manufacturing, or production changes based on the technical content disclosed in this application are merely routine technical means for a person skilled in the art and should not be considered to constitute a deficiency in the disclosure of the present application.

[0162] The term "embodiment" as used in this application refers to specific features, structures, or characteristics described in conjunction with the embodiment that can be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily mean that the embodiment is the same, nor does it mean that it is mutually exclusive with other embodiments and is independent or optional. It is understood, either explicitly or implicitly, by those skilled in the art that the embodiments described in this application can be combined with other embodiments when there is no conflict.

[0163] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of patent protection. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be determined by the appended claims.

Claims

1. A DC component detection method, characterized in that: The method is applied to a power converter, the power converter comprising a transformer, a primary circuit and a secondary circuit respectively connected to the transformer, and the method comprises: Detecting a port voltage of a primary circuit or a secondary circuit of the power converter to obtain a detection signal, wherein the port voltage is a voltage of a port where the primary circuit or the secondary circuit is connected to the transformer; Based on the detection signal, it is determined whether a DC component exists in the power converter.

2. The method according to claim 1, wherein: The detecting of the port voltage of the primary circuit or the secondary circuit of the power converter to obtain a detection signal comprises: Sampling the port voltage to obtain a sampling signal; The sampled signal is compared with a preset reference signal to obtain a detection signal.

3. The method according to claim 2, wherein: The sampling of the port voltage to obtain a sampling signal comprises: Performing differential sampling on the port voltage to obtain a differential signal; A DC bias is applied to the differential signal to obtain a sampling signal.

4. The method according to claim 1, wherein: The determining, based on the detection signal, whether the power converter has a DC component comprises: When the duty cycle of the detection signal satisfies a preset duty cycle determination condition, it is determined that no DC component exists in the power converter; otherwise, a DC component exists.

5. The method according to claim 4, wherein: The duty cycle determination conditions include: The duty cycle of the detection signal is equal to a preset duty cycle; or The duty cycle of the detection signal including the positive duty cycle information of the port voltage is equal to the duty cycle of the detection signal including the negative duty cycle information of the port voltage.

6. A DC component suppression method, characterized in that: The method comprises: Based on the DC component detection method according to any one of claims 1 to 5, detecting whether there is a DC component in the power converter; When a DC component exists, the DC component is suppressed based on the duty cycle of the detection signal.

7. The method according to claim 6, wherein: The step of suppressing the DC component based on the duty cycle of the detection signal includes: When the duty cycle of the detection signal is within a preset duty cycle threshold range, determining a driving duty cycle of a corresponding primary circuit or a secondary circuit based on the duty cycle of the detection signal and a reference duty cycle; A corresponding driving signal is generated based on the driving duty cycle, and the corresponding primary circuit or secondary circuit is driven to suppress the DC component.

8. The method according to claim 7, wherein: The reference duty cycle is a set value, or is obtained based on a positive duty cycle and a negative duty cycle of the port voltage.

9. The method according to claim 7, wherein: The step of suppressing the DC component based on the duty cycle of the detection signal further comprises: When the duty cycle of the detection signal is outside the duty cycle threshold range, the power converter is controlled to stop working.

10. A DC component detection device, characterized in that: The device is applied to a power converter, the power converter includes a transformer, a primary circuit and a secondary circuit respectively connected to the transformer, and the device includes: A detection circuit, used to detect the port voltage of the primary circuit or the secondary circuit of the power converter to obtain a detection signal, wherein the port voltage is the voltage of the port where the primary circuit or the secondary circuit is connected to the transformer; The control circuit is connected to the detection circuit and is used to determine whether a DC component exists in the power converter based on the detection signal.

11. The device according to claim 10, wherein: The detection circuit comprises: A sampling circuit, used for sampling the port voltage to obtain a sampling signal; The comparison circuit is connected to the sampling circuit and is used to compare the sampling signal with a preset reference signal to obtain a detection signal.

12. The device according to claim 11, wherein The sampling circuit comprises: A differential sampling circuit is used to perform differential sampling on the port voltage to obtain a differential signal; The DC bias circuit is connected to the differential sampling circuit and is used to apply a DC bias to the differential signal to obtain a sampling signal.

13. The device according to claim 12, wherein: The sampling circuit also includes: The isolation transmission circuit is connected between the DC bias circuit and the comparison circuit, and is used for isolating and transmitting the sampling signal to the comparison circuit.

14. The device according to claim 10, wherein: The control circuit is used for determining that the power converter does not have a DC component when the duty cycle of the detection signal meets a preset duty cycle determination condition, and otherwise determining that the power converter has a DC component.

15. The device according to claim 14, wherein: The duty cycle determination conditions include: The duty cycle of the detection signal is equal to a preset duty cycle; or The duty cycle of the detection signal including the positive duty cycle information of the port voltage is equal to the duty cycle of the detection signal including the negative duty cycle information of the port voltage.

16. A DC component suppression device, characterized in that: The device is applied to a power converter, the power converter includes a transformer, a primary circuit and a secondary circuit respectively connected to the transformer, and the device includes: According to any one of claims 10 to 15, when a DC component exists, the control circuit of the DC component detection device suppresses the DC component based on the duty cycle of the detection signal.

17. The device according to claim 16, wherein: Also includes a drive circuit connected to the control circuit, When the duty cycle of the detection signal is outside a preset duty cycle threshold range, the control circuit controls the power converter to stop working; and / or When the duty cycle of the detection signal is within the duty cycle threshold range, the control circuit acquires the driving duty cycle based on the duty cycle of the detection signal, and the driving circuit generates a corresponding driving signal based on the driving duty cycle to suppress the DC component.

18. A power converter, characterized in that: The power converter comprises: a transformer, a primary circuit and a secondary circuit respectively connected to the transformer, and A DC component detection device as described in any one of claims 10-15.

19. The power converter according to claim 18, wherein: The primary circuit or the secondary circuit is any one of a full-bridge inverter circuit, a half-bridge inverter circuit, a full-bridge rectifier circuit, a half-bridge rectifier circuit, a multi-level inverter circuit, and a cycloconversion circuit.

20. The power converter according to claim 18, wherein: The power converter is a DC-DC converter or a DC-AC converter.

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