Charging circuit with safety detection function, method and vehicle-mounted charger

Abstract

The invention relates to the technical field of vehicle-mounted charging, and provides a charging circuit with a safety detection function, a method and a vehicle-mounted charger. According to the application, the voltage sampling of the first charging branch at the input end is multiplexed, the input current theoretical value of the second charging branch is calculated according to the voltage sampling value of the first charging branch at the input end and the current sampling value corresponding to the charging load, and the input current theoretical value is the low-voltage side current of the second charging branch; more measurement means are provided for low-voltage side current detection, a redundancy detection mechanism of the low-voltage side current is constructed, and the safety guarantee capability of the vehicle-mounted charger in the operation process is further improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of vehicle charging, and in particular to a charging circuit with a safety detection function, a method and a vehicle charger. BACKGROUND

[0002] With the rapid development of the new energy vehicle industry, vehicle chargers integrated with an OBC (On-Board Charger) and a DC / DC converter (Direct Current to Direct Current Converter) are gradually applied to new energy vehicles. Through the integrated topology of the vehicle charger, on the one hand, the direct current power provided by the power grid is converted into bus direct current, and the bus direct current is converted into the charging current of the power battery; on the other hand, the low-voltage side direct current provided by the low-voltage battery in the vehicle is converted into the charging current of the high-voltage side, thereby achieving the additional charging function of the power battery. Based on the above two aspects, the power density of the vehicle charger is significantly improved, and the cost and volume thereof are reduced, thereby meeting the needs of new energy vehicles for compact and efficient charging equipment.

[0003] Since the low-voltage side current is directly related to the safety of the low-voltage power grid, the low-voltage side current needs to be detected during the working process of the vehicle charger to ensure charging safety. However, only relying on the current sensor arranged on the low-voltage side to measure the current is too single in measurement means, and it is difficult to meet the high requirements of the vehicle charging scene on safety. SUMMARY

[0004] To provide a basic understanding of some aspects of the disclosed embodiments, a brief introduction is given below. The introduction is not an overview, nor is it intended to identify key / important components or delineate the scope of these embodiments, but to serve as a prelude to the detailed description below.

[0005] In view of the above-mentioned shortcomings of the prior art, the present application provides a charging circuit with a safety detection function, a method and a vehicle charger to expand the application range of the vehicle charger.

[0006] The application provides a charging circuit with a safety detection function, comprising: an integrated module, provided with a first charging branch and a second charging branch, wherein the first charging branch is used for converting a first direct current power into a first charging voltage corresponding to a charging load, and the second charging branch is used for converting a second direct current power into a second charging voltage corresponding to the charging load; and a detection module, used for calculating a voltage sampling value at an input end of the first charging branch by using a resonance waveform of the first charging branch, obtaining an average output current at an output end of the first charging branch, calculating the average output current according to a current sampling value corresponding to the charging load, obtaining an output current theoretical value at an output end of the second charging branch, and performing power reverse calculation according to the output current theoretical value to obtain an input current theoretical value at an input end of the second charging branch, so as to perform current safety detection on the second charging branch according to the input current theoretical value.

[0007] In an embodiment of the application, the circuit further comprises: a filter unit connected to an external alternating current power supply, wherein the filter unit is used for filtering the external alternating current power supply to obtain an alternating current input voltage; a relay unit connected to the filter unit, wherein the relay unit is used for controlling an input working condition corresponding to the alternating current input voltage; and a power factor correction unit connected to the relay unit, wherein the power factor correction unit is used for converting the alternating current input voltage into the first direct current power.

[0008] In an embodiment of the application, the integrated module comprises: a primary unit used for performing energy conversion between the first direct current power and a transformer; a first secondary unit used for performing energy conversion between the transformer and the charging load, wherein the first charging branch is sequentially composed of the primary unit, the transformer and the first secondary unit; a second secondary unit used for performing energy conversion between the transformer and the second direct current power, wherein the second charging branch is sequentially composed of the second secondary unit, the transformer and the first secondary unit; and the transformer, wherein the primary unit, the first secondary unit and the second secondary unit are coupled to each other through the transformer.

[0009] In an embodiment of the application, the detection module calculates the average output current by the following formula: , wherein, is the average output current, is a preset coefficient based on a switching characteristic, is a resonance current capacitance value between the primary unit and the first secondary unit, is a resonance current inductance value between the primary unit and the first secondary unit, is a switching frequency of the integrated module. a switching period of the integrated module, a first voltage sampling value, a winding turn ratio corresponding to the first auxiliary side unit and the primary side unit, a resonant frequency, a phase shift angle.

[0010] In an embodiment of the present application, the circuit further comprises: a first sampling unit arranged at an input end of the first charging branch, wherein the first sampling unit is configured to sample a voltage at the input end of the first charging branch to obtain a first voltage sampling value; a second sampling unit arranged at the charging load, wherein the second sampling unit is configured to sample a current corresponding to the charging load to obtain a second current sampling value; and a third sampling unit arranged at an input end of the second charging branch, wherein the third sampling unit is configured to sample a current at the input end of the second charging branch to obtain a third current sampling value.

[0011] In an embodiment of the present application, the detection module performs current safety detection on the second charging branch according to the input current theoretical value in the following manner: determining a sampling signal state corresponding to the third sampling unit according to the input current theoretical value and the third current sampling value; if the sampling signal state corresponding to the third sampling unit includes a fault signal state, and a state duration corresponding to the fault signal state is greater than or equal to a preset first time threshold, controlling the second charging branch to stop outputting current; and if the sampling signal state corresponding to the third sampling unit includes a normal signal state, comparing the third current sampling value with a preset fifth determination threshold to determine a safety state of the second charging branch according to a comparison result.

[0012] In an embodiment of the present application, the detection module determines the sampling signal state corresponding to the third sampling unit in the following at least one manner: if the third current sampling value is greater than or equal to a preset first determination threshold, determining the sampling signal state of the third sampling unit as a fault signal state; if the third current sampling value is less than a preset second determination threshold, determining the sampling signal state of the third sampling unit as a fault signal state, wherein the first determination threshold is greater than the second determination threshold; if a sampling signal deviation between the input current theoretical value and the third current sampling value is greater than or equal to a preset third determination threshold, determining the sampling signal state of the third sampling unit as a fault signal state; and if a current direction of the output current theoretical value is different from a current direction corresponding to the third current sampling value, determining the sampling signal state of the third sampling unit as a fault signal state.

[0013] In an embodiment of the present application, the detection module compares the third current sampling value with the preset fifth determination threshold, to determine the safety state of the second charging branch according to the comparison result: if the third current sampling value is greater than or equal to the preset fifth determination threshold, the branch state of the second charging branch is determined as a branch overcurrent state; and if the state duration corresponding to the branch overcurrent state is greater than or equal to a preset second duration threshold, an overcurrent fault report is generated.

[0014] The present application also provides a charging method with safety detection function, comprising: calculating the voltage sampling value at the input end of the first charging branch by using the resonant waveform of the first charging branch, to obtain the average output current at the output end of the first charging branch, wherein the integrated module is provided with the first charging branch and the second charging branch, the first charging branch is used to convert the first direct current power supply into the first charging voltage corresponding to the charging load, and the second charging branch is used to convert the second direct current power supply into the second charging voltage corresponding to the charging load; calculating the average output current according to the current sampling value corresponding to the charging load, to obtain the output current theoretical value at the output end of the second charging branch; and performing power reverse calculation according to the output current theoretical value, to obtain the input current theoretical value at the input end of the second charging branch, so as to perform current safety detection on the second charging branch according to the input current theoretical value.

[0015] The present application also provides a vehicle-mounted charger comprising the above-mentioned circuit.

[0016] The present application has the following beneficial effects: By calculating the voltage sampling value at the input end of the first charging branch, the average output current of the first charging branch is obtained, and then the average output current is calculated according to the current sampling value corresponding to the charging load, to obtain the output current theoretical value of the second charging branch, and the input current theoretical value of the second charging branch is obtained by performing power reverse calculation according to the output current theoretical value, so as to perform current safety detection on the second charging branch according to the input current theoretical value. In this way, by multiplexing the voltage sampling at the input end of the first charging branch, the input current theoretical value of the second charging branch is calculated according to the voltage sampling value at the input end of the first charging branch and the current sampling value corresponding to the charging load, and the input current theoretical value is the low-voltage side current of the second charging branch, which not only provides more measurement means for low-voltage side current detection, but also constructs a redundant detection mechanism for low-voltage side current, further improving the safety guarantee capability of the vehicle-mounted charger during operation. BRIEF DESCRIPTION OF DRAWINGS

[0017] The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate embodiments consistent with the application and, together with the description, further serve to explain the principles of the application. It is to be understood that the drawings are only schematic, and that they do not necessarily correspond to the actual size, shape or relative arrangement of the components shown in the drawings.

[0018] In the drawings: Figure 1 is a structural schematic diagram of a charging circuit with a safety detection function in an embodiment of the application; Figure 2 is a structural schematic diagram of a vehicle charger in an embodiment of the application; Figure 3 is a structural schematic diagram of another vehicle charger in an embodiment of the application; Figure 4 is a structural schematic diagram of a detection module in an embodiment of the application; Figure 5 is a flow schematic diagram of a safety detection method applied to a function layer in an embodiment of the application; Figure 6 is a flow schematic diagram of a safety detection method applied to a function monitoring layer in an embodiment of the application; Figure 7 is a flow schematic diagram of a safety detection method applied to an abnormality monitoring unit in an embodiment of the application; Figure 8 is a flow schematic diagram of a charging method with a safety detection function in an embodiment of the application. DETAILED DESCRIPTION

[0019] The specific embodiments of the application will be described below with reference to the drawings, and those skilled in the art can easily understand other advantages and effects of the application from the content disclosed in the specification. The application can also be implemented or applied by different specific embodiments, and the details in the specification can be modified or changed based on different views and applications without departing from the spirit of the application. The following embodiments and features in the embodiments can be combined with each other without conflict.

[0020] It should be noted that the diagrams provided in the following embodiments only illustrate the basic concept of the application in a schematic manner, and the drawings only show the components related to the application in the drawings, not the number, shape and size of the components when actually implemented. The actual implementation of each component may be a random change, and the component layout pattern may be more complex.

[0021] In the following description, numerous specific details are discussed in order to provide a thorough explanation of the embodiments of the application. It will be apparent, however, to one skilled in the art, that the embodiments of the application can be practiced without these specific details. In other instances, well-known structures and devices are not described in detail in order to avoid obscuring the embodiments of the application.

[0022] The terms "first", "second", and the like, as used in the description and the claims of the application and the preceding drawings, are used to differentiate between similar objects, not necessarily described in a particular sequential or chronological order. It is to be understood that the use of these terms in the description are not to be construed to limit the scope of the embodiments of the application described herein. Furthermore, the terms "comprise" and "comprising" and any variations thereof are intended to cover a non-exclusive inclusion.

[0023] Unless otherwise indicated, the term "plurality" means two or more.

[0024] In the present application, the character " / " represents that the front and rear objects are in an "or" relationship. For example, A / B means: A or B.

[0025] The term "and / or" is a description of the association relationship between objects, which means that there can be three relationships. For example, A and / or B means: A or B, or, A and B, three relationships.

[0026] In combination Figure 1 As shown, the present application provides a charging circuit with safety detection function, which comprises an integrated module 101 and a detection module 102.

[0027] The integrated module 101 is provided with a first charging branch and a second charging branch, wherein the first charging branch is used to convert the first direct current power into the first charging voltage corresponding to the charging load, and the second charging branch is used to convert the second direct current power into the second charging voltage corresponding to the charging load.

[0028] The detection module 102 is used to calculate the voltage sampling value of the input end of the first charging branch by using the resonance waveform of the first charging branch, to obtain the average output current of the output end of the first charging branch, and to calculate the average output current according to the current sampling value corresponding to the charging load, to obtain the output current theoretical value of the output end of the second charging branch, and to perform power inverse calculation according to the output current theoretical value, to obtain the input current theoretical value of the input end of the second charging branch, so as to perform current safety detection on the second charging branch according to the input current theoretical value.

[0029] The charging circuit with the safety detection function provided in the application obtains the average output current of the first charging branch by calculating the voltage sampling value at the input end of the first charging branch, calculates the output current theoretical value of the second charging branch according to the current sampling value corresponding to the charging load, and calculates the input current theoretical value of the second charging branch according to the output current theoretical value, so as to perform current safety detection on the second charging branch according to the input current theoretical value. In this way, the input current theoretical value of the second charging branch is calculated according to the voltage sampling value at the input end of the first charging branch and the current sampling value corresponding to the charging load by reusing the voltage sampling at the input end of the first charging branch, and the input current theoretical value is the low-voltage side current of the second charging branch, which not only provides more measurement means for low-voltage side current detection, but also constructs a redundant detection mechanism for the low-voltage side current, and further improves the safety guarantee capability of the vehicle charger in the running process.

[0030] In combination Figure 2 As shown in the drawings, the application provides a vehicle charger, which includes a filter unit 201, a relay unit 202, a power factor correction unit 203 and an integrated module 101.

[0031] Optionally, the circuit further includes: a filter unit connected to an external AC power supply, wherein the filter unit is configured to filter the external AC power supply to obtain an AC input voltage; a relay unit connected to the filter unit, wherein the relay unit is configured to control an input working condition corresponding to the AC input voltage; and a power factor correction unit connected to the relay unit, wherein the power factor correction unit is configured to convert the AC input voltage into a first DC power supply.

[0032] The filter unit 201 is connected to an external AC power supply, and the filter unit 201 is configured to filter the external AC power supply to obtain an AC input voltage.

[0033] The relay unit 202 is connected to the filter unit 201, and the relay unit 202 is configured to control an input working condition corresponding to the AC input voltage, wherein the input working condition includes a three-phase input working condition, a single-phase input working condition and an inverter output working condition.

[0034] In some embodiments, the three-phase input working condition includes that the vehicle charger is connected to a three-phase AC power grid, and a three-phase rectifier circuit is used to convert three-phase AC power into DC power to charge the power battery.

[0035] In some embodiments, the single-phase input working condition includes that the vehicle charger is connected to a single-phase AC power grid, and a single-phase rectifier circuit is used to convert single-phase AC power into DC power to charge the power battery. In some embodiments, the inverter output mode includes that the on-board charger converts the direct current of the power battery into alternating current, to realize a "vehicle-to-grid (V2G)" function or a "vehicle-to-load (V2L)" function.

[0036] The power factor correction unit 203 is connected to the relay unit 202.

[0037] In some embodiments, the power factor correction unit 203 is configured to convert the alternating current input voltage into a stable first direct current power supply, and to improve the power factor of the system by adjusting the input current waveform to be in phase with the voltage.

[0038] Optionally, the integrated module includes: a primary side unit configured to perform energy conversion between the first direct current power supply and the transformer; a first secondary side unit configured to perform energy conversion between the transformer and the charging load, wherein the first charging branch is sequentially composed of the primary side unit, the transformer and the first secondary side unit; a second secondary side unit configured to perform energy conversion between the transformer and the second direct current power supply, wherein the second charging branch is sequentially composed of the second secondary side unit, the transformer and the first secondary side unit; and the transformer, wherein the primary side unit, the first secondary side unit and the second secondary side unit are coupled to each other through the transformer.

[0039] The integrated module 101 includes a primary side unit 204, a first secondary side unit 205, a second secondary side unit 206 and a transformer 207, wherein the primary side unit 204, the first secondary side unit 205 and the second secondary side unit 206 are coupled to each other through the transformer.

[0040] The primary side unit 204 is connected to the power factor correction unit 203 and the primary winding of the transformer 207, respectively, wherein the primary side unit 204 is configured to perform energy conversion between alternating current and direct current, including: performing energy conversion on the first direct current power supply to obtain alternating current corresponding to the primary winding, or performing energy conversion on alternating current corresponding to the primary winding to realize a "vehicle-to-grid (V2G)" function.

[0041] The first secondary side unit 205 is connected to the first secondary winding of the transformer 207 and the charging load, respectively, wherein the first secondary side unit 205 is configured to perform energy conversion between alternating current and direct current, including: performing energy conversion on alternating current corresponding to the first secondary winding to realize a charging function on the charging load, or using the charging load as a load power supply, and obtaining alternating current corresponding to the first secondary winding by performing energy conversion on the load power supply.

[0042] In some embodiments, the charging load includes a power battery.

[0043] The second secondary side unit 206 is connected to the second secondary side winding of the transformer 207 and the second DC power supply, and is configured to convert energy between AC and DC, including converting energy of the second DC power supply to obtain AC corresponding to the second secondary side winding, or converting energy of AC corresponding to the second secondary side winding to charge the second DC power supply.

[0044] In some embodiments, the second DC power supply includes a low-voltage battery or an energy storage battery.

[0045] The transformer 207 includes a primary winding, a first secondary winding, and a second secondary winding.

[0046] In some embodiments, the integrated module forms a plurality of charging branches, including: a first charging branch composed of the primary side unit, the transformer, and the first secondary side unit in sequence, wherein the first charging branch is configured to convert the first DC power supply into a first charging voltage corresponding to the charging load; a second charging branch composed of the second secondary side unit, the transformer, and the first secondary side unit in sequence, wherein the second charging branch is configured to convert the second DC power supply into a second charging voltage corresponding to the charging load; a third charging branch composed of the primary side unit, the transformer, and the second secondary side unit in sequence, wherein the third charging branch is configured to convert the first DC power supply into a third charging voltage corresponding to the second DC power supply; a fourth charging branch composed of the first secondary side unit, the transformer, and the second secondary side unit in sequence, wherein the fourth charging branch is configured to convert the charging load into a fourth charging voltage corresponding to the second DC power supply; and a fifth charging branch composed of the first secondary side unit, the transformer, and the primary side unit in sequence, wherein the fifth charging branch is configured to convert the charging load into a fifth charging voltage corresponding to the external power grid to realize a “vehicle-to-grid (V2G)” function.

[0047] In some embodiments, the input end of the second charging branch is a low-voltage side, and the output end of the second charging branch is a high-voltage side.

[0048] In combination Figure 3 with the above, the present application provides a vehicle-mounted charger, which includes a filter unit 201, a relay unit 202, a power factor correction unit 203, and an integrated module 101.

[0049] The first end of the filter unit 201 is connected to an external AC power supply.

[0050] The relay unit 202 includes a circuit switch , a protection resistor , and a common-mode inductor , wherein the first end of the circuit switch is connected to the first end of the protection resistor , and the circuit switch is connected in parallel to the protection resistor circuit switch second end of the common mode inductor first end of the common mode inductor.

[0051] The power factor correction unit 203 comprises a first bridge arm, a second bridge arm and a filter capacitor , wherein the first bridge arm, the second bridge arm and the filter capacitor are connected in parallel with each other, a midpoint of the first bridge arm is connected to a second end of the common mode inductor , a midpoint of the second bridge arm is connected to a first end of the circuit switch .

[0052] The integrated module 101 comprises a primary side unit 204, a first secondary side unit 205, a second secondary side unit 206 and a transformer 207.

[0053] The primary side unit 204 comprises a third bridge arm, a fourth bridge arm, a resonant inductor , a resonant capacitor and an excitation inductor , wherein a first end of the third bridge arm is connected to a first end of the first bridge arm, a first end of the second bridge arm, a first end of the filter capacitor and a first end of the fourth bridge arm respectively, a second end of the third bridge arm is connected to a second end of the first bridge arm, a second end of the second bridge arm, a second end of the filter capacitor and a second end of the fourth bridge arm respectively, a midpoint of the third bridge arm is connected to a first end of the resonant inductor , a second end of the resonant inductor is connected to a first end of the excitation inductor and a first end of the primary winding respectively, a midpoint of the fourth bridge arm is connected to a first end of the resonant capacitor , a second end of the resonant capacitor is connected to a second end of the excitation inductor and a second end of the primary winding respectively.

[0054] The first secondary side unit 205 comprises a fifth bridge arm, a sixth bridge arm, a seventh bridge arm, a resonant inductor , a resonant capacitor and a resonant capacitor , wherein a first end of the fifth bridge arm is connected to a first end of the sixth bridge arm, a first end of the seventh bridge arm and a positive pole of the charging load respectively, a second end of the fifth bridge arm is connected to a second end of the sixth bridge arm, a second end of the seventh bridge arm and a negative pole of the charging load respectively, a midpoint of the fifth bridge arm is connected to a first end of the first secondary winding through the resonant capacitor , a midpoint of the sixth bridge arm is connected to a second end of the first secondary winding, a midpoint of the seventh bridge arm is connected to a third end of the first secondary winding through the resonant capacitor and the resonant inductor in sequence.

[0055] The second auxiliary side unit 206 includes an eighth bridge arm and a ninth bridge arm. The first end of the eighth bridge arm is connected to the positive pole of the second DC power supply through a blocking capacitor The second end of the eighth bridge arm is connected to the negative pole of the second DC power supply, and the midpoint of the eighth bridge arm is connected to the negative pole of the second DC power supply through a filter inductor The first end of the ninth bridge arm is connected to the third end of the second auxiliary side winding through a blocking capacitor The second end of the ninth bridge arm is connected to the negative pole of the second DC power supply, and the midpoint of the ninth bridge arm is connected to the negative pole of the second DC power supply through a filter inductor The first end of the second auxiliary side winding is connected to the first end of the second auxiliary side winding, and the second end of the second auxiliary side winding is connected to the second end of the second auxiliary side winding in sequence through a filter inductor The positive pole of the second DC power supply is connected to the protection switch, and the eighth bridge arm and the ninth bridge arm are each provided with a freewheeling diode.

[0056] Optionally, the circuit further includes: a first sampling unit arranged at the input end of the first charging branch, wherein the first sampling unit is configured to sample the voltage at the input end of the first charging branch to obtain a first voltage sampling value; a second sampling unit arranged at the charging load, wherein the second sampling unit is configured to sample the current corresponding to the charging load to obtain a second current sampling value; and a third sampling unit arranged at the input end of the second charging branch, wherein the third sampling unit is configured to sample the current at the input end of the second charging branch to obtain a third current sampling value.

[0057] In combination with Figure 3 As shown in the figure, the vehicle-mounted charger provided by the present application is provided with a first sampling unit, a second sampling unit and a third sampling unit.

[0058] The first sampling unit is arranged between the power factor correction unit 203 and the primary side unit 204.

[0059] The second sampling unit is arranged between the first auxiliary side unit 205 and the input end of the charging load.

[0060] The third sampling unit is arranged between the filter inductor and the protection switch.

[0061] In some embodiments, the first sampling unit is originally used to detect the direct current voltage after conversion of the alternating current power supply, and the second sampling unit is originally used to detect the input current of the charging load. On this basis, the application multiplexes the first sampling unit and the second sampling unit, calculates the difference value according to the voltage sampling value output by the first sampling unit and the current sampling value output by the second sampling unit, obtains the output current theoretical value of the second charging branch, and then calculates the input current theoretical value of the second charging branch according to the output current theoretical value. The input current theoretical value is the low-voltage side current of the second charging branch. In this way, the diagnostic coverage of the first sampling unit and the second sampling unit in the safety monitoring mechanism is improved, and the safety protection of the low-voltage side is achieved. At the same time, the multiplexed sampling unit makes the device used by the vehicle-mounted charger less, low in cost, small in size, and capable of meeting the demand of ASIL B safety level, ensuring the reliable low-voltage output of the integrated product and improving the safety of the low-voltage side power supply.

[0062] Optionally, the detection module calculates the average output current through formula (1): Formula (1) In formula (1), is the average output current, is a preset coefficient based on the switching characteristic, is the resonance current capacitance value between the primary unit and the first secondary unit, is the resonance current inductance value between the primary unit and the first secondary unit, is the switching frequency of the integrated module, is the switching period of the integrated module, is the first voltage sampling value, is the winding turn ratio corresponding to the first secondary unit and the primary unit, is the resonance frequency, is the phase shift angle.

[0063] In some embodiments, the core principle of formula (1) is based on the energy transmission characteristic of the phase-shifted full-bridge (PSFB, Phase-Shifted Full-Bridge) resonant converter, which depends on the resonance waveform of the first charging branch, including: combining the modulation effect of the phase shift angle on the resonance waveform, reflecting the influence of the switching tube action timing on energy transmission, wherein, characterizes the peak value of the resonant waveform after phase shift, characterizes the reference peak value when there is no phase shift, and the ratio of the two reflects the “discount” effect of phase shift on resonant energy; the average current is calculated by the charge and discharge charge amount of the resonant capacitor, characterizes the charge and discharge charge amount of the resonant capacitor in one switching period, the average output current is calculated by dividing the charge and discharge charge amount by the switching period, and the first voltage sampling value is combined As a phase shift correction factor, a calculation formula of average output current is formed, wherein, preset coefficient The bipolar switching characteristic of the full-bridge converter, that is, twice resonance process in each cycle.

[0064] Optionally, the detection module performs current safety detection on the second charging branch according to the input current theoretical value in the following manner: determining a sampling signal state corresponding to the third sampling unit according to the input current theoretical value and the third current sampling value; if the sampling signal state corresponding to the third sampling unit includes a fault signal state, and a state duration corresponding to the fault signal state is greater than or equal to a preset first duration threshold, controlling the second charging branch to stop outputting current; and if the sampling signal state corresponding to the third sampling unit includes a normal signal state, comparing the third current sampling value according to a preset fifth judgment threshold, to determine a safety state of the second charging branch according to a comparison result.

[0065] In combination with Figure 4 As shown in the figure, the application provides a detection module, which includes a control unit, a driving unit, an abnormality monitoring unit and a storage unit.

[0066] In some embodiments, the detection module is implemented by a processor, a control chip or a unit on a chip, etc.

[0067] Optionally, the detection module determines the sampling signal state corresponding to the third sampling unit in the following at least one manner: if the third current sampling value is greater than or equal to a preset first judgment threshold, determining the sampling signal state of the third sampling unit as a fault signal state; if the third current sampling value is less than a preset second judgment threshold, determining the sampling signal state of the third sampling unit as a fault signal state, wherein the first judgment threshold is greater than the second judgment threshold; if a sampling signal deviation between the input current theoretical value and the third current sampling value is greater than or equal to a preset third judgment threshold, determining the sampling signal state of the third sampling unit as a fault signal state; and if a current direction of the output current theoretical value is different from a current direction corresponding to the third current sampling value, determining the sampling signal state of the third sampling unit as a fault signal state.

[0068] The control unit includes a function layer and a function monitoring layer, wherein the function layer is used for safety monitoring, and the function monitoring layer is used as a redundancy check of the function layer to improve the safety level of the low-voltage side current signal.

[0069] The function layer is connected with the first sampling unit, the second sampling unit and the third sampling unit respectively, wherein the function layer is used for determining the sampling signal state corresponding to the third sampling unit, and calculating the input current theoretical value according to the first voltage sampling value output by the first sampling unit and the second current sampling value output by the second sampling unit, and inputting the input current theoretical value into the function monitoring layer.

[0070] In combination Figure 5 As shown in the specification, the application provides a safety detection method applied to a functional layer, comprising: Step S501, setting an abnormal signal condition corresponding to the functional layer in advance; Wherein, the abnormal signal condition corresponding to the functional layer comprises a first determination condition, a second determination condition and a third determination condition; Wherein, the first determination condition comprises that the third current sampling value is greater than or equal to a preset first determination threshold value; Wherein, the second determination condition comprises that the third current sampling value is less than a preset second determination threshold value; Wherein, the sampling signal deviation between the input current theoretical value and the third current sampling value is greater than or equal to a preset third determination threshold value; Step S502, calculating the input current theoretical value of the second charging branch according to the first voltage sampling value and the second current sampling value, and obtaining the third current sampling value output by the third sampling unit; Step S503, detecting whether the third sampling unit meets the abnormal signal condition, if yes, jumping to step S504, if not, jumping to step S507; Step S504, determining the sampling signal state of the third sampling unit as a fault signal state; Step S505, judging whether the state duration of the fault signal state is greater than or equal to a first duration threshold value, if yes, jumping to step S506, if not, jumping to step S502; Wherein, the first duration threshold value is used to judge whether the fault signal state is a mature fault; Step S506, stopping the output current of the second charging branch through the driving unit.

[0071] Step S607, determining the sampling signal state of the third sampling unit as a normal signal state, and keeping the output current of the second charging branch through the driving unit, and jumping to step S502.

[0072] The functional monitoring layer is connected to the third sampling unit, wherein the functional monitoring layer is used to determine the sampling signal state corresponding to the third sampling unit, and determine the branch state of the second charging branch.

[0073] In some embodiments, the functional monitoring layer is independent of the overcurrent monitoring of the abnormal monitoring unit, and is also used to determine the branch state of the second charging branch, and the functional monitoring layer can report overcurrent faults by itself and set a safety mode.

[0074] In some embodiments, the function monitoring layer performs redundant checking of the third sampling unit according to the input current theoretical value and the output current theoretical value output by the function layer, prevents signal checking errors of the function layer, and avoids systematic failure, wherein when the detection results of the function layer and the function monitoring layer are different, the function monitoring layer triggers a fault response.

[0075] In combination Figure 6 As shown in the drawings, the present application provides a safety detection method applied to a function monitoring layer, comprising: Step S601, an abnormal signal condition corresponding to the function monitoring layer is set in advance; The abnormal signal condition corresponding to the function monitoring layer includes a fourth determination condition and a fifth determination condition. The fourth determination condition includes that the current direction of the output current theoretical value is different from the current direction corresponding to the third current sampling value. The fifth determination condition includes that the sampling signal deviation between the input current theoretical value and the third current sampling value is greater than or equal to a preset fourth determination threshold. Step S602, a third current sampling value output by a third sampling unit is obtained; Step S603, an input current theoretical value and an output current theoretical value of a second charging branch are obtained from the function layer; Step S604, it is detected whether the third sampling unit meets the abnormal signal condition, if yes, step S605 is skipped, and if no, step S607 is skipped; Step S605, the sampling signal state of the third sampling unit is determined as a fault signal state; Step S606, it is judged whether the state duration of the fault signal state is greater than or equal to a first duration threshold, if yes, step S607 is skipped, and if no, step S602 is skipped; The first duration threshold is used to judge whether the fault signal state is mature. Step S607, the output current of the second charging branch is stopped through a driving unit, and step S602 is skipped; Step S608, the sampling signal state of the third sampling unit is determined as a normal signal state, the output current of the second charging branch is maintained through the driving unit, and step S602 is skipped; If the third current sampling value, the input current theoretical value and the output current theoretical value do not meet the abnormal signal condition, it is determined that the third sampling unit recovers from the fault signal state.

[0076] The driving unit is configured to drive the switch tube of the integrated module 101 and the power factor correction unit 203 through a control signal, so as to control the current output corresponding to the power factor correction unit 203, the primary side unit 204, the first secondary side unit 205 and the second secondary side unit 206, respectively.

[0077] Optionally, the detection module compares the third current sampling value with the preset fifth determination threshold value to determine the safety state of the second charging branch according to a comparison result, wherein if the third current sampling value is greater than or equal to the preset fifth determination threshold value, the branch state of the second charging branch is determined as a branch overcurrent state; and if the state duration corresponding to the branch overcurrent state is greater than or equal to the preset second duration threshold value, an overcurrent fault report is generated.

[0078] The abnormality monitoring unit is connected to the third sampling unit, wherein the abnormality monitoring unit is configured to determine whether the third current sampling value has an overcurrent fault, and trigger the driving unit to cut off the second charging branch and generate an overcurrent fault report when the third current sampling value has the overcurrent fault.

[0079] In combination with Figure 7 As shown in the accompanying drawings, the present application provides a safety detection method applied to an abnormality monitoring unit, comprising: Step S701: obtaining a third current sampling value output by a third sampling unit; Step S702: determining whether the third current sampling value is greater than or equal to a fifth determination threshold value, if yes, jumping to step S703, and if no, jumping to step S706; Step S703: determining a branch state of the second charging branch as a branch overcurrent state; Step S704: determining whether a state duration corresponding to the branch overcurrent state is greater than or equal to a second duration threshold value, if yes, jumping to step S705, and if no, jumping to step S701; Step S705: triggering the driving unit to cut off the second charging branch and generating an overcurrent fault report, and jumping to step S701; Step S706: determining the branch state of the second charging branch as a branch normal state, and jumping to step S701.

[0080] The storage unit is configured to store a gain parameter and a bias parameter of the sampling module, wherein the gain parameter represents an amplification multiple of the sampling signal, so as to avoid signal clipping or noise amplification, and the bias parameter represents a direct current voltage superimposed on the sampling signal, so as to avoid negative signal loss and improve a small signal signal-to-noise ratio.

[0081] In combination with Figure 8 As shown in the accompanying drawings, the present application provides a charging method with a safety detection function, comprising: Step S801: calculating a voltage sampling value at an input end of the first charging branch by using a resonant waveform of the first charging branch to obtain an average output current at an output end of the first charging branch; The integrated module is provided with the first charging branch and the second charging branch; The first charging branch is used for converting the first direct current power into a first charging voltage corresponding to the charging load, and the second charging branch is used for converting the second direct current power into a second charging voltage corresponding to the charging load. In step S802, an average output current is calculated according to a current sampling value corresponding to the charging load, to obtain an output current theoretical value of the second charging branch at an output end. In step S803, power reverse calculation is performed according to the output current theoretical value, to obtain an input current theoretical value of the second charging branch at an input end, so as to perform current safety detection on the second charging branch according to the input current theoretical value.

[0082] The charging method with safety detection function provided in the application is used to calculate the average output current of the first charging branch at the input end by sampling the voltage value of the first charging branch at the input end, to calculate the output current theoretical value of the second charging branch according to the average output current and the current sampling value corresponding to the charging load, to perform power reverse calculation according to the output current theoretical value, to obtain the input current theoretical value of the second charging branch, and to perform current safety detection on the second charging branch according to the input current theoretical value. In this way, the voltage sampling of the first charging branch at the input end is reused, the input current theoretical value of the second charging branch is calculated according to the voltage sampling value of the first charging branch at the input end and the current sampling value corresponding to the charging load, and the input current theoretical value is the low-voltage side current of the second charging branch. This not only provides more measurement means for low-voltage side current detection, but also constructs a redundant detection mechanism for low-voltage side current, and further improves the safety guarantee capability of the vehicle-mounted charger in the running process.

[0083] The application further provides a vehicle-mounted charger comprising the above circuit.

[0084] The above description and drawings are illustrative of embodiments of the present disclosure and are not intended to be limiting. Other embodiments can include structural, logical, electrical, process, and other changes. Embodiments are merely representative of possible variations. Individual components and functions are optional and the order of operations can vary. Portions and sub-combinations of some embodiments can be included or replaced in or by other embodiments. Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. As used in the description of the embodiments and the claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. Similarly, the term "and / or" as used herein refers to any and all possible combinations of one or more of the associated listed items. Additionally, as used in this application, the term "comprises" and variations thereof do not intend to preclude the presence or addition of one or more other items to those stated in the compositions, integers, steps, operations, elements, and / or components. Without more limitations, an element defined by the phrase "comprises a..." does not exclude the presence of additional identical elements in the process, method, or apparatus including the element. In this document, each embodiment focuses on the differences from other embodiments, and the same or similar parts between embodiments can be referred to each other. For the method, product, etc. disclosed by the embodiments, if it corresponds to the method part disclosed by the embodiments, the relevant part can be referred to the description of the method part.

[0085] Those skilled in the art can understand that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be realized by electronic hardware or a combination of computer software and electronic hardware. Whether the functions are realized in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application. Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the above-described system, device and unit can refer to the corresponding process in the foregoing method embodiments, which will not be repeated here.

[0086] In the embodiments disclosed herein, the disclosed methods, products (including but not limited to devices, apparatuses, etc.) can be implemented in other manners. For example, the described device embodiments are merely schematic. For example, the division of the units is merely a logical function division. There can be another division manner for the actual implementation, for example, multiple units or components can be combined or integrated into another system, or some of the components can be ignored or not executed. In addition, the displayed or discussed mutual couplings or direct couplings or communication connections can be indirect couplings or communication connections through some interfaces, devices or units, and can be in electrical, mechanical or other forms. The unit illustrated as a separate component can or can not be physically separate, and can or can not be a physical component. Some or all of the units can be selected according to actual needs to implement the embodiments. In addition, the units in the application can be integrated into a processing unit, or each unit can exist physically as a separate entity, or two or more units can be integrated into a unit.

[0087] The flowcharts and block diagrams in the drawings show the architectural, functional and operational aspects of possible implementations of systems, methods and computer program products according to the present application. In this regard, each block in the flowcharts or block diagrams can represent a module, a program segment or a portion of code that contains one or more executable instructions for implementing the specified logical functions. In some alternative implementations, the functions noted in the blocks can occur in a different order than that shown in the drawings. For example, two consecutive blocks can actually be executed substantially in parallel, and they can sometimes be executed in reverse order, depending on the functions involved. In the descriptions corresponding to the flowcharts and block diagrams in the drawings, the operations or steps corresponding to different blocks can also occur in an order different from that disclosed in the description, and sometimes there is no specific order between different operations or steps. For example, two consecutive operations or steps can actually be executed substantially in parallel, and they can sometimes be executed in reverse order, depending on the functions involved. Each block in the block diagrams and / or flowcharts, and the combination of blocks in the block diagrams and / or flowcharts, can be implemented by a dedicated hardware-based system that performs the specified functions or actions, or can be implemented by a combination of dedicated hardware and computer instructions.

Claims

1. A charging circuit with a safety detection function, characterized in that, include: The integrated module is provided with a first charging branch and a second charging branch, wherein the first charging branch is used to convert a first DC power supply into a first charging voltage corresponding to the charging load, and the second charging branch is used to convert the second DC power supply into a second charging voltage corresponding to the charging load. The detection module is used to calculate the voltage sampling value at the input end of the first charging branch using the resonant waveform of the first charging branch, to obtain the average output current at the output end of the first charging branch, and to calculate the theoretical value of the output current at the output end of the second charging branch based on the current sampling value corresponding to the charging load. It also performs power back calculation based on the theoretical value of the output current to obtain the theoretical value of the input current at the input end of the second charging branch, so as to perform current safety detection on the second charging branch based on the theoretical value of the input current.

2. The circuit according to claim 1, characterized in that, The circuit also includes: A filtering unit is connected to an external AC power supply, wherein the filtering unit is used to filter the external AC power supply to obtain an AC input voltage; A relay unit is connected to the filter unit, wherein the relay unit is used to control the input conditions corresponding to the AC input voltage; A power factor correction unit is connected to the relay unit, wherein the power factor correction unit is used to convert the AC input voltage into a first DC power supply.

3. The circuit according to claim 1, characterized in that, The integrated module includes: The primary-side unit is used for energy conversion between the first DC power supply and the transformer; The first secondary unit is used to perform energy conversion between the transformer and the charging load, wherein the first charging branch is composed of the primary unit, the transformer and the first secondary unit in sequence; The second secondary unit is used to perform energy conversion between the transformer and the second DC power supply, wherein the second charging branch is composed of the second secondary unit, the transformer and the first secondary unit in sequence; The transformer, wherein the primary side unit, the first secondary side unit, and the second secondary side unit are coupled to each other through the transformer.

4. The circuit according to claim 3, characterized in that, The detection module calculates the average output current using the following formula: In the formula, The average output current, These are preset coefficients based on switching characteristics. The resonant current capacitance value between the primary side unit and the first secondary side unit. The inductance value is the resonant current between the primary side unit and the first secondary side unit. The switching frequency of the integrated module. The switching cycle of the integrated module. This is the first voltage sample value. This refers to the ratio of the number of winding turns corresponding to the first secondary unit and the primary unit. The resonant frequency, This is the phase shift angle.

5. The circuit according to any one of claims 1 to 4, characterized in that, The circuit also includes: A first sampling unit is disposed at the input terminal of the first charging branch, wherein the first sampling unit is used to sample the voltage at the input terminal of the first charging branch to obtain a first voltage sample value: A second sampling unit is disposed on the charging load, wherein the second sampling unit is used to sample the current corresponding to the charging load to obtain a second current sampling value; The third sampling unit is located at the input end of the second charging branch. The third sampling unit is used to sample the current at the input end of the second charging branch to obtain a third current sampling value.

6. The circuit according to claim 5, characterized in that, The detection module performs current safety detection on the second charging branch based on the theoretical value of the input current in the following manner: The sampling signal state corresponding to the third sampling unit is determined based on the theoretical value of the input current and the third current sample value. If the sampling signal state corresponding to the third sampling unit includes a fault signal state, and the duration of the state corresponding to the fault signal state is greater than or equal to a preset first duration threshold, then the second charging branch is controlled to stop outputting current. If the sampling signal state corresponding to the third sampling unit includes a normal signal state, the third current sampling value is compared according to a preset fifth determination threshold to determine the safety state of the second charging branch based on the comparison result.

7. The circuit according to claim 6, characterized in that, The detection module determines the sampling signal state corresponding to the third sampling unit through at least one of the following methods: If the third current sample value is greater than or equal to the preset first determination threshold, then the sampling signal state of the third sampling unit is determined to be a fault signal state. If the third current sample value is less than the preset second determination threshold, then the sampling signal state of the third sampling unit is determined to be a fault signal state, wherein the first determination threshold is greater than the second determination threshold. If the sampling signal deviation between the theoretical value of the input current and the third current sample value is greater than or equal to the preset third judgment threshold, then the sampling signal state of the third sampling unit is determined as a fault signal state. If the direction of the theoretical value of the output current is different from the direction of the current corresponding to the third current sample value, then the sampling signal state of the third sampling unit is determined to be a fault signal state.

8. The circuit according to claim 6, characterized in that, The detection module compares the third current sample value according to a preset fifth judgment threshold in the following way to determine the safety status of the second charging branch based on the comparison result: If the third current sampling value is greater than or equal to the preset fifth determination threshold, then the branch state of the second charging branch is determined to be the branch overcurrent state. If the duration of the overcurrent state corresponding to the branch is greater than or equal to a preset second duration threshold, an overcurrent fault report is generated.

9. A charging method with a safety detection function, characterized in that, include: The average output current of the first charging branch at the output terminal is obtained by calculating the voltage sample value at the input terminal of the first charging branch using the resonant waveform of the first charging branch. The integrated module is provided with the first charging branch and the second charging branch. The first charging branch is used to convert the first DC power supply into the first charging voltage corresponding to the charging load, and the second charging branch is used to convert the second DC power supply into the second charging voltage corresponding to the charging load. The average output current is calculated based on the current sampling value corresponding to the charging load to obtain the theoretical value of the output current of the second charging branch at the output end. Based on the theoretical value of the output current, the power is calculated inversely to obtain the theoretical value of the input current at the input end of the second charging branch, so as to perform current safety detection on the second charging branch based on the theoretical value of the input current.

10. A vehicle charger, characterized in that, The circuit includes any one of claims 1 to 8.

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