Non-uniform mobility detection circuit and device for parallel AC lines, and vehicle-mounted charger

Abstract

The utility model discloses a non-uniform mobility detection circuit and device of a parallel AC line, and a vehicle-mounted charger, and relates to the technical field of power supplies, the non-uniform mobility detection circuit of the parallel AC line comprises a first sampling module which is connected to a first cable of the parallel AC line and is used for collecting the voltage of the first cable; a second sampling module which is connected to a second cable of the parallel AC line and is used for collecting the voltage of the second cable; the first input end of a primary winding of the isolation transformer is connected with the output end of the first sampling module, and the second input end of the primary winding is connected with the output end of the second sampling module; the input end of the operational amplifier is connected with the output end of the secondary winding of the isolation transformer, and the operational amplifier is used for determining the voltage difference between the voltage of the first cable and the voltage of the second cable. The objective of the utility model is to realize non-uniform mobility detection of parallel AC lines with low cost on the basis of not occupying too much wiring space.

Description

Technical Field

[0001] This utility model relates to the field of power supply technology, and in particular to a non-uniform current detection circuit, device, and on-board charger for a parallel AC line. Background Technology

[0002] In multi-phase devices such as onboard chargers (OBCs), two phase wires are often connected in parallel to increase single-phase power in order to meet the needs of the global power grid. However, this parallel capacity expansion method is prone to uneven current distribution between the two phase wires due to external wire breakage, internal component damage, or impedance differences between the parallel phases. Excessive current unevenness between the two phase wires can lead to cable overload and burnout.

[0003] Currently, the current in one wire is typically measured using a Hall sensor or a combination of a sampling resistor and an operational amplifier. This measured current is then compared to the total current in both wires to determine the current imbalance. However, in practical applications, both methods require additional measures (such as isolation and heat dissipation) and additional measurement of the total current in both wires to accurately determine the current imbalance. This approach is not only costly but also requires significant wiring space. Utility Model Content

[0004] The main objective of this invention is to provide a non-uniform current detection circuit for parallel AC lines, aiming to achieve the detection of non-uniform current in parallel AC lines at low cost without occupying excessive wiring space.

[0005] To achieve the above objectives, this utility model proposes a non-uniform flow detection circuit for a parallel AC line, the non-uniform flow detection circuit for the parallel AC line comprising:

[0006] A first sampling module is connected to the first cable of the parallel AC line and is used to collect the voltage of the first cable.

[0007] The second sampling module is connected to the second cable of the parallel AC line and is used to collect the voltage of the second cable.

[0008] An isolation transformer, wherein the first input terminal of the primary winding of the isolation transformer is connected to the output terminal of the first sampling module, and the second input terminal of the primary winding is connected to the output terminal of the second sampling module;

[0009] An operational amplifier, the input of which is connected to the output of the secondary winding of the isolation transformer, is used to determine the voltage difference between the voltage of the first cable and the voltage of the second cable.

[0010] In one embodiment, the first sampling module is a first sampling resistor, and the second sampling module is a second sampling resistor.

[0011] In one embodiment, the impedance value of the primary winding of the isolation transformer is greater than a preset impedance threshold to limit the current.

[0012] In one embodiment, the uneven current detection circuit of the parallel AC line further includes a current limiting module;

[0013] The first end of the current limiting module is connected to the output end of the first sampling module, and the second end of the current limiting module is connected to the first input end of the primary winding of the isolation transformer.

[0014] In one embodiment, the current limiting module is a current limiting resistor.

[0015] In one embodiment, the resistance value of the current-limiting resistor is greater than the resistance value of the first sampling resistor and the resistance value of the second sampling resistor.

[0016] In one embodiment, the uneven current detection circuit of the parallel AC line further includes a voltage stabilizing module;

[0017] The voltage regulator module is connected in parallel between the input terminal of the operational amplifier and the output terminal of the secondary winding of the isolation transformer.

[0018] In one embodiment, the voltage regulator module is a voltage regulator resistor.

[0019] In addition, to achieve the above objectives, this utility model also provides a non-uniform flow detection device for parallel AC lines, which includes a main control unit and the above-mentioned non-uniform flow detection circuit for parallel AC lines.

[0020] The main control unit is connected to the output of the operational amplifier of the uneven flow detection circuit.

[0021] In addition, to achieve the above objectives, this utility model also provides an on-board charger, which includes a parallel AC line and an uneven flow detection circuit for the parallel AC line.

[0022] This invention provides a non-uniform current detection circuit for a parallel AC line. The circuit includes a first sampling module, a second sampling module, an isolation transformer, and an operational amplifier. The first and second sampling modules are respectively connected to the first and second cables of the parallel AC line to collect the voltages of the first and second cables. The first input terminal of the primary winding of the isolation transformer is connected to the output terminal of the first sampling module, the second input terminal of the primary winding is connected to the output terminal of the second sampling module, and the output terminal of the secondary winding of the isolation transformer is connected to the input terminal of the operational amplifier to achieve isolation between the AC side and the low-voltage side. Therefore, the voltage difference between the first and second cables can be determined by integrating the collected voltages from the operational amplifier. Since the voltage difference is positively correlated with the current difference, and the current difference reflects the non-uniform current of the parallel AC line, the non-uniform current of the parallel AC line can be determined by determining the voltage difference between the first and second cables. Therefore, this invention can accurately determine the uneven current of a parallel AC circuit without the need for additional measures or additional detection of the total current of the two wires. Thus, it can detect the uneven current of a parallel AC circuit at low cost without occupying too much wiring space. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0024] Figure 1 A schematic diagram of the circuit structure for detecting uneven flow in a parallel AC line using a Hall sensor, provided for an embodiment of this utility model.

[0025] Figure 2 A schematic diagram of the circuit structure for detecting uneven flow in a parallel AC line using a combination of a sampling resistor and an operational amplifier, provided for an embodiment of this utility model.

[0026] Figure 3 A schematic diagram of the uneven flow detection circuit for a parallel AC line provided in the first embodiment of this utility model;

[0027] Figure 4 A schematic diagram of the uneven flow detection circuit for a parallel AC line provided in the second embodiment of this utility model;

[0028] Figure 5A schematic diagram of the uneven flow detection circuit for a parallel AC line provided in the fourth embodiment of this utility model;

[0029] Figure 6 A schematic diagram of the uneven current detection circuit of the parallel AC line when the current limiting module provided in the fourth embodiment of this utility model is a current limiting resistor;

[0030] Figure 7 A schematic diagram of the uneven flow detection circuit for a parallel AC line provided in the fifth embodiment of this utility model;

[0031] Figure 8 A schematic diagram of the uneven current detection circuit of the parallel AC line after combining the various embodiments provided in this utility model;

[0032] Figure 9 A schematic diagram of the uneven flow rate detection device for parallel AC circuits provided in this embodiment of the present invention.

[0033] The purpose, features, and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings.

[0034] Explanation of icon numbers:

[0035] 10. First sampling module; 20. Second sampling module; 30. Current limiting module; 40. Voltage regulating module; T1. Isolation transformer; A1. Operational amplifier; R1. First sampling resistor; R2. Second sampling resistor;

[0036] R3, current-limiting resistor; R4, voltage-regulating resistor; 100, main control unit; R, sampling resistor; HALL, Hall sensor. Detailed Implementation

[0037] It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0038] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0039] It should be noted that the descriptions involving "first," "second," etc., in this utility model are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope claimed by this utility model.

[0040] In multi-phase devices such as on-board chargers, two phase lines are often connected in parallel to increase single-phase power in order to meet the needs of the global power grid. However, this parallel capacity expansion method is prone to uneven current distribution between the two phase lines due to external wire breakage, internal component damage, or impedance differences between the parallel phases. Excessive current unevenness between the two phase lines can lead to cable overload and burnout.

[0041] Currently, the current in one wire is typically measured using a Hall effect sensor or a combination of a sampling resistor and an operational amplifier. This measured current is then compared to the total current in both wires to determine the current imbalance between them. For details, please refer to [link / reference]. Figure 1 and Figure 2 However, when using Hall effect sensors to determine the uneven flow rate between two wires, additional heat dissipation measures are required to accurately determine the uneven flow rate. Furthermore, Hall effect sensors experience significant losses when the current is high. When using a combination of sampling resistors and operational amplifiers to determine the uneven flow rate between two wires, additional isolation measures are required to accurately determine the uneven flow rate.

[0042] Therefore, in practical applications, whether using a Hall sensor or a combination of sampling resistor and operational amplifier, additional measures (such as isolation and heat dissipation) are required, and the total current of the two wires must be detected to accurately determine the uneven current distribution between the two wires. This not only increases costs but also requires more wiring space.

[0043] Based on this, the present invention provides a non-uniform current detection circuit for a parallel AC circuit. In the first embodiment of the present invention, please refer to... Figure 3The uneven current detection circuit for the parallel AC line includes a first sampling module 10, a second sampling module 20, an isolation transformer T1, and an operational amplifier A1. The first sampling module 10 is connected to the first cable L1 of the parallel AC line, and the second sampling module 20 is connected to the second cable L2 of the parallel AC line. The first input terminal of the primary winding of the isolation transformer T1 is connected to the output terminal of the first sampling module 10, and the second input terminal of the primary winding is connected to the output terminal of the second sampling module 20. The input terminal of the operational amplifier A1 is connected to the output terminal of the secondary winding of the isolation transformer T1. The first sampling module 10 is used to acquire the voltage of the first cable L1; the second sampling module 20 is used to acquire the voltage of the second cable L2; and the operational amplifier A1 is used to determine the voltage difference between the voltage of the first cable L1 and the voltage of the second cable L2.

[0044] It is understandable that during the process of acquiring the voltage of the first cable L1 and the second cable L2 through the first sampling module 10 and the second sampling module 20, even if the acquired voltage is very small, the uneven current of the parallel AC line can still be accurately determined after the operation amplifier. Therefore, when actually using the uneven current detection circuit of the parallel AC line provided in this embodiment to determine the uneven current of the parallel AC line, it is only required that the voltages of the two cables can be acquired, and there is no requirement for the magnitude of the acquired voltages. Therefore, the performance of the components in the uneven current detection circuit has little impact on the accurate determination of the uneven current. Therefore, when selecting circuit components, low-cost components that require less wiring space can be selected to form the uneven current detection circuit.

[0045] This embodiment provides a non-uniform flow detection circuit for a parallel AC line. The circuit includes a first sampling module 10, a second sampling module 20, an isolation transformer T1, and an operational amplifier A1. The first sampling module 10 and the second sampling module 20 are respectively connected to the first cable L1 and the second cable L2 of the parallel AC line to collect the voltage of the first cable L1 and the voltage of the second cable L2. The first input terminal of the primary winding of the isolation transformer T1 is connected to the output terminal of the first sampling module 10, the second input terminal of the primary winding is connected to the output terminal of the second sampling module 20, and the output terminal of the secondary winding of the isolation transformer T1 is connected to the input terminal of the operational amplifier A1 to achieve isolation between the AC side and the low-voltage side. Therefore, the voltage difference between the two cables can be determined by integrating the collected voltages of the first cable L1 and the second cable L2 through the operational amplifier A1. Since the voltage difference and current difference are positively correlated, and the current difference reflects the uneven current distribution in a parallel AC circuit, the uneven current distribution in the parallel AC circuit can be determined by measuring the voltage difference between the first cable L1 and the second cable L2. Therefore, this embodiment can accurately determine the uneven current distribution in a parallel AC circuit without requiring additional measures or additional detection of the total current of the two cables. This allows for the detection of uneven current distribution in a parallel AC circuit at low cost without occupying excessive wiring space.

[0046] Based on the first embodiment described above, a second embodiment of the uneven current detection circuit for parallel AC lines of this utility model is proposed. For the second embodiment of this utility model, please refer to... Figure 4 The first sampling module 10 can be the first sampling resistor R1, and the second sampling module 20 can be the second sampling resistor R2.

[0047] It should be noted that the first sampling resistor R1 can be an actual resistor or an equivalent resistor formed by the module on the first cable L1; the second sampling resistor R2 can be an actual resistor or an equivalent resistor formed by the module on the second cable L2; the resistance value of the first sampling resistor R1 can be the same as or different from the resistance value of the second sampling resistor R2, and this embodiment does not make specific limitations on this.

[0048] For example, to help understand the technical principle that "voltage difference and current difference are positively correlated," let's take the total current of the first cable L1 and the second cable L2 as I, and the resistance of the first sampling resistor R1 and the second sampling resistor R2 as r. The current flowing through the first cable L1 can be expressed as I1 = 0.5I + 0.5ΔI, and the current flowing through the second cable L2 as I2 = 0.5I - 0.5ΔI. Therefore, the voltage U1 of the first cable L1 can be determined as U1 = (0.5I + 0.5ΔI) * r, and the voltage U2 of the second cable L2 as U2 = (0.5I - 0.5ΔI) * r. After processing by operational amplifier A1, the voltage difference ΔU between the first cable L1 and the second cable L2 can be determined as β * r * ΔI, where β is the amplification factor of the operational amplifier. Thus, it can be seen that the larger the voltage difference ΔU, the larger the current difference ΔI.

[0049] Based on the first and / or second embodiments described above, a third embodiment of the uneven current detection circuit for parallel AC lines of this utility model is proposed. In the third embodiment of this utility model, the impedance value of the primary winding of the isolation transformer T1 is greater than a preset impedance threshold to limit the current.

[0050] It should be noted that the preset impedance threshold refers to the minimum impedance value that the primary winding of the isolation transformer T1 needs to achieve in order to better limit the current. The preset impedance threshold can be a default value or can be flexibly set by the user according to the actual situation. This embodiment does not impose specific limitations on this.

[0051] This embodiment sets the impedance of the primary winding of the isolation transformer T1 to be greater than a preset impedance threshold, enabling the isolation transformer T1 to effectively limit current using its primary winding. This avoids the phenomenon of current flowing from the second cable L2 to the first cable L1 due to the voltage difference between the first cable L1 and the second cable L2, which could cause the cables to burn out.

[0052] Based on the first, second, and / or third embodiments described above, a fourth embodiment of the non-uniform current detection circuit for parallel AC lines of this utility model is proposed. For the fourth embodiment of this utility model, please refer to... Figure 5 The uneven current detection circuit of the parallel AC line may also include a current limiting module 30; the first end of the current limiting module 30 is connected to the output end of the first sampling module 10, and the second end of the current limiting module 30 is connected to the first input end of the primary winding of the isolation transformer T1.

[0053] Understandably, to prevent current from flowing from the second cable L2 to the first cable L1 due to the voltage difference between the first cable L1 and the second cable L2, which could cause the cables to burn out, a current-limiting module 30 can be directly installed between the cable and the primary winding of the isolation transformer T1 to limit the current.

[0054] In one feasible implementation, please refer to Figure 6 The current limiting module 30 can be a current limiting resistor R3.

[0055] It should be noted that the current-limiting resistor R3 can be an actual resistor or an equivalent resistor; this embodiment does not specifically limit it in this way. To ensure that the current-limiting resistor R3 can effectively limit the current, the resistance value of the current-limiting resistor R3 needs to be set much larger than the resistance values ​​of the first sampling resistor R1 and the second sampling resistor R2.

[0056] Based on the first, second, third, and / or fourth embodiments described above, a fifth embodiment of the uneven current detection circuit for parallel AC lines of this utility model is proposed. For the fifth embodiment of this utility model, please refer to... Figure 7 The uneven current detection circuit of the parallel AC line may also include a voltage regulator module 40; the voltage regulator module 40 is connected in parallel between the input terminal of the operational amplifier A1 and the output terminal of the secondary winding of the isolation transformer T1.

[0057] In one possible implementation, the voltage regulator module 40 can be a voltage regulator resistor R4.

[0058] In this embodiment, a voltage regulator module 40 is set between the input terminal of operational amplifier A1 and the output terminal of the secondary winding of isolation transformer T1 to stabilize the voltage output from isolation transformer T1 to operational amplifier A1, thereby improving the detection accuracy of uneven current in parallel AC lines.

[0059] It should be noted that the first sampling module 10, the second sampling module 20, the current limiting module 30, and the voltage regulating module 40 mentioned in the above embodiments can be flexibly configured according to actual conditions. For example, assuming the first sampling module 10 is a first sampling resistor R1, the second sampling module 20 is a second sampling resistor R2, the current limiting module 30 is a current limiting resistor R3, and the voltage regulating module 40 is a voltage regulating resistor R4, then the following can be obtained: Figure 8 The diagram shows the structure of the uneven flow detection circuit for the parallel AC circuit.

[0060] The above examples are only for the purpose of assisting in understanding this utility model and do not constitute a limitation on the uneven current detection circuit of the parallel AC line of this utility model. Any simple modifications based on this technical concept are within the protection scope of this utility model.

[0061] This utility model also provides a device for detecting uneven current distribution in a parallel AC circuit; please refer to [reference needed]. Figure 9 The uneven flow rate detection device for the parallel AC line may include a main control unit 100 and the aforementioned uneven flow rate detection circuit for the parallel AC line; the main control unit 100 is connected to the output terminal of the operational amplifier A1 of the uneven flow rate detection circuit.

[0062] It should be noted that the main control unit 100 can be an MCU (Microcontroller Unit), or other types of controllers or processors. This embodiment does not specifically limit this.

[0063] In one feasible implementation, the main control unit 100 can be used to compare the voltage difference between the voltage of the first cable L1 and the voltage of the second cable L2 with a preset voltage difference threshold. When it is determined that the voltage difference is greater than the preset voltage difference threshold, the power unit is shut down to achieve protection. The preset voltage difference threshold is used as a basis for judging whether the current on the two cables of the parallel AC line is excessively uneven. The preset voltage difference threshold can be a default value or can be flexibly set by the user according to actual conditions; this embodiment does not specifically limit this setting.

[0064] The structure of the uneven flow detection circuit for parallel AC lines in this embodiment can be referred to the above embodiments, and will not be repeated here. Naturally, since the uneven flow detection device for parallel AC lines in this embodiment includes all the technical solutions of all the above embodiments of the uneven flow detection circuit for parallel AC lines, and the achieved technical effects are exactly the same, it will not be repeated here.

[0065] This utility model also provides an on-board charger, which includes a parallel AC line and a non-uniform flow detection circuit for the parallel AC line. The structure of the non-uniform flow detection circuit for the parallel AC line can be referred to the above embodiments, and will not be repeated here. Naturally, since the on-board charger of this embodiment includes all the technical solutions of all embodiments of the non-uniform flow detection circuit for the parallel AC line, and the achieved technical effects are exactly the same, it will not be repeated here.

[0066] The above are merely preferred embodiments of this utility model and do not limit the patent scope of this utility model. Any equivalent structural or procedural transformations made based on the description and drawings of this utility model, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this utility model.

Claims

1. A non-uniform current detection circuit for a parallel AC circuit, characterized in that, The uneven flow detection circuit of the parallel AC line includes: A first sampling module is connected to the first cable of the parallel AC line and is used to collect the voltage of the first cable. The second sampling module is connected to the second cable of the parallel AC line and is used to collect the voltage of the second cable. An isolation transformer, wherein the first input terminal of the primary winding of the isolation transformer is connected to the output terminal of the first sampling module, and the second input terminal of the primary winding is connected to the output terminal of the second sampling module; An operational amplifier, the input of which is connected to the output of the secondary winding of the isolation transformer, is used to determine the voltage difference between the voltage of the first cable and the voltage of the second cable.

2. The uneven current detection circuit for parallel AC lines as described in claim 1, characterized in that, The first sampling module is a first sampling resistor, and the second sampling module is a second sampling resistor.

3. The uneven current detection circuit for parallel AC lines as described in claim 1, characterized in that, The impedance value of the primary winding of the isolation transformer is greater than a preset impedance threshold to limit the current.

4. The uneven current detection circuit for a parallel AC line as described in any one of claims 1 to 3, characterized in that, The uneven current detection circuit of the parallel AC line also includes a current limiting module; The first end of the current limiting module is connected to the output end of the first sampling module, and the second end of the current limiting module is connected to the first input end of the primary winding of the isolation transformer.

5. The uneven current detection circuit for parallel AC lines as described in claim 4, characterized in that, The current limiting module is a current limiting resistor.

6. The uneven current detection circuit for parallel AC lines as described in claim 5, characterized in that, The resistance value of the current-limiting resistor is greater than the resistance value of the first sampling resistor and the resistance value of the second sampling resistor.

7. The uneven current detection circuit for a parallel AC line as described in any one of claims 1 to 3, characterized in that, The uneven flow detection circuit of the parallel AC line also includes a voltage stabilizing module; The voltage regulator module is connected in parallel between the input terminal of the operational amplifier and the output terminal of the secondary winding of the isolation transformer.

8. The uneven current detection circuit for parallel AC lines as described in claim 7, characterized in that, The voltage regulator module is a voltage regulator resistor.

9. A device for detecting uneven current distribution in a parallel AC circuit, characterized in that, The uneven flow rate detection device for the parallel AC line includes a main control unit and an uneven flow rate detection circuit for the parallel AC line as described in any one of claims 1 to 8. The main control unit is connected to the output of the operational amplifier of the uneven flow detection circuit.

10. An on-board charger, characterized in that, The on-board charger includes a parallel AC circuit and an uneven flow detection circuit for the parallel AC circuit as described in any one of claims 1 to 8.

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