A power supply adaptive load detection and protection circuit

Abstract

The present invention relates to a power supply adaptive load detection and protection circuit, which at least includes: a first load switch, which is connected in series to the output end of the power supply; a sampling resistor Rs, which is connected in series to the output end of the first load switch; a differential sampling amplifier circuit, which is connected in parallel to both ends of the sampling resistor Rs to receive and transmit the voltage difference between the two ends of the sampling resistor Rs; at least one second load switch connected in parallel to the output end of the sampling resistor Rs, and at least one second load is connected in series to the output end of the at least one second load switch; an MCU, which can control the on and off of at least one first load switch and / or the second load switch according to the output signal of the differential sampling amplifier circuit. The advantage of the present invention is that it can achieve accurate detection of load current without being affected by device parameters. At the same time, the load switch is used to ensure the reliability of the power supply system, avoiding the deviation of the test results due to the difference in electronic component parameters.

Description

Technical Field

[0001] The present invention relates to the field of electronic power technology, and in particular to a power supply adaptive load detection and protection circuit. Background Art

[0002] Power supply circuits often require designs with multiple loads. Accurately measuring load currents and disconnecting abnormal loads in response to load fluctuations are crucial. Conventional resistive direct sampling circuits are subject to the discrete nature of electronic component parameters, leading to variations in performance across different applications. Furthermore, if an abnormality such as a load short circuit occurs, the inability to disconnect the abnormal load can affect the operation of other normal loads, causing the entire power supply system to malfunction. Existing solutions utilize a current transformer connected in series with the load circuit, performing differential amplification on the transformer's output voltage, and using this amplified voltage to estimate the load current.

[0003] Chinese patent CN 110208597B discloses a self-powered wireless current monitoring system based on a single-winding current transformer. The system includes an acquisition element and a monitoring circuit. The monitoring circuit includes a filtering, rectifying, and current sampling module, a charging control and energy storage module, a signal conditioning module, a microcontroller, and a wireless transmission module. The acquisition element generates an AC current and outputs it to the filtering, rectifying, and current sampling module. The filtering, rectifying, and current sampling module generates a DC voltage and two analog voltage signal outputs. The charging control and energy storage module supplies power to the signal conditioning module, the microcontroller, and the wireless transmission module. The signal conditioning module processes the two analog voltage signals to obtain an analog voltage signal and outputs it to the microcontroller. The microcontroller monitors and controls the charging of the charging control and energy storage module and generates a current monitoring signal that is sent to the wireless transmission module for wireless transmission. The system has the advantage of using a conventional single-winding current transformer for both power acquisition and current sensing, resulting in low cost and a small size.

[0004] The disadvantages of the above patents are: (1) the current transformer has poor accuracy when sampling small currents; (2) the coupling degree of the current transformer is easily affected by external interference, which directly affects the accuracy of current sampling; (3) the difference in the parameters of the current transformer itself will directly affect the sampling results.

[0005] To this end, this invention proposes a load detection and protection circuit designed to ensure consistent load detection and protect the reliability of the power supply. This invention employs an adaptive load detection circuit that autonomously calculates the actual load current by detecting the sampled voltage values ​​before and after the load is connected. Furthermore, different load switches are designed within the circuit to controllably disconnect abnormal loads.

[0006] In addition, on the one hand, there are differences in understanding among those skilled in the art; on the other hand, the applicant studied a large number of documents and patents when making the present invention, but due to space limitations, not all details and contents are listed in detail. However, this does not mean that the present invention does not have the characteristics of these prior arts. On the contrary, the present invention already has all the characteristics of the prior art, and the applicant reserves the right to add relevant prior art to the background technology. Summary of the Invention

[0007] In view of the deficiencies of the prior art, the present invention provides a power supply adaptive load detection and protection circuit, aiming to solve at least one or more technical problems existing in the prior art.

[0008] To achieve the above objectives, the present invention provides a power supply adaptive load detection and protection circuit, which at least includes:

[0009] a first load switch connected in series to an output terminal of the power supply;

[0010] a sampling resistor Rs, connected in series to the output end of the first load switch;

[0011] A differential sampling amplifier circuit is connected in parallel to the sampling resistor Rs to receive and transmit the voltage difference between the two ends of the sampling resistor Rs;

[0012] At least one second load switch is connected in parallel to the output end of the sampling resistor Rs, and at least one second load is connected in series to the output end of the at least one second load switch;

[0013] The MCU can control the on / off of at least one first load switch and / or the second load switch according to the output signal of the differential sampling and amplifying circuit.

[0014] Preferably, the present invention provides a detection method based on the above-mentioned power supply adaptive load detection and protection circuit, the method comprising: the MCU records the voltage signal for representing the voltage difference between the two ends of the sampling resistor Rs outputted via the differential sampling amplifier circuit before the power supply circuit starts to work with load as an initial sampling signal; the MCU records the voltage signal for representing the voltage difference between the two ends of the sampling resistor Rs outputted via the differential sampling amplifier circuit after the power supply circuit starts to work with load as a secondary sampling signal; the MCU calculates the difference between the secondary sampling signal and the initial sampling signal to obtain a voltage difference Δu, and combines the voltage difference Δu with the resistance value of the sampling resistor Rs to obtain the actual increased load current ΔI.

[0015] Preferably, the detection method also includes: the MCU can determine whether there is an abnormal load state in the circuit based on the numerical changes of the voltage difference Δu and / or the load current ΔI, and control the on and off of the corresponding second load switch when any second load is abnormal.

[0016] Preferably, the step of the MCU judging whether there is a load abnormality in the circuit based on the numerical changes of the voltage difference Δu and / or the load current ΔI includes: when either the voltage difference Δu and / or the load current ΔI is not within the threshold range of the standard load voltage and / or current, the MCU determines that there is a load abnormality in the circuit.

[0017] Preferably, when the MCU determines that there is a load abnormality in the circuit based on the voltage difference Δu and / or the load current ΔI, it can determine the circuit where the abnormal load is located based on the difference between the detection voltage and / or current at each load end and the standard threshold voltage and / or current.

[0018] Preferably, the differential sampling and amplifying circuit includes a plurality of voltage-dividing resistors and at least one operational amplifier.

[0019] Preferably, the state of the power supply circuit before starting to work with load is: the first load switch is in the on state, and the second load switch is in the off state, and no second load is connected to the circuit.

[0020] Preferably, the state of the power supply circuit after starting to work with load is: the first load switch is in the on state, and at least one second load switch is in the on state, and at least one second load is connected to the circuit.

[0021] Preferably, the abnormal load state includes at least one of a second load disconnection, an overload, and a short circuit.

[0022] Preferably, load disconnection is manifested as a decrease in load current and an increase in load voltage at any load terminal.

[0023] Preferably, load overload and short circuit are manifested as an increase in load current and / or a decrease in load voltage associated with the sampling resistor Rs, and load disconnection is manifested as a decrease in load current and / or an increase in load voltage associated with the sampling resistor Rs.

[0024] The advantage of the present invention is that it can accurately detect the load current without being affected by device parameters, while using a load switch to ensure the reliability of the power supply system. The present invention solves the problem starting from the sampling difference, focusing on the differences in the sampling results. By controlling the load switch, load detection is performed before and after the power supply is loaded, and the load current is automatically calculated, truly achieving accurate detection of the load current, avoiding deviations in the test results due to differences in electronic component parameters. At the same time, the load switch can be controlled to cut off abnormal loads, ensuring the overall stability of the power supply system. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 1 is a structural diagram of a differential sampling and amplifying circuit according to a preferred embodiment of the present invention;

[0026] Figure 21 is a schematic diagram of a power supply adaptive load detection and protection circuit according to a preferred embodiment of the present invention;

[0027] Figure 3 The figure is a schematic diagram of the state of a power supply adaptive load detection and protection circuit before the power supply circuit works under load according to a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0028] The following is a detailed description with reference to the accompanying drawings.

[0029] The present invention provides a power supply adaptive load detection and protection circuit, such as Figure 1-Figure 3 As shown, the method includes:

[0030] S1: Add a load switch 1 and a sampling resistor Rs to the original power output terminal C1. The load switch 1 can be controlled by the MCU for on-off. Connect a differential sampling amplifier circuit in parallel across the sampling resistor Rs. The differential sampling amplifier circuit can be composed of voltage divider resistors R1, R2, R3, and R4 and an operational amplifier Op1. The output signal of Op1 is fed back to the MCU.

[0031] S2: The sampling resistor Rs is connected to load switch 2 and load switch 3 respectively. Load switch 2 and load switch 3 are connected to load 2 and load 3 respectively. Both load switch 2 and load switch 3 can be turned on and off by the MCU.

[0032] S3: Before the power circuit starts working with load, load switch 2 and load switch 3 are both in the off state. At this time, load switch 1 is turned on. Due to the influence of the differential sampling and amplifier circuit in the circuit, a certain voltage difference will exist on the sampling resistor Rs. The voltage difference is fed back to the MCU through the differential amplifier sampling circuit and will be recorded as the initial sampling value.

[0033] S4: After the power circuit starts working with load, load switch 2 and load switch 3 are turned on. Load 2 and load 3 are connected to the circuit. The load current increases, causing the voltage difference on the sampling resistor Rs to increase. The new voltage difference is fed back to the MCU and recorded as the secondary sampling value:

[0034] S5: The MCU calculates the difference between the secondary sampling value and the initial sampling value, and calculates the obtained voltage difference with the sampling resistor Rs. The result is the actual increase in load current. Since it is a difference calculation, the calculation result is not affected by the differences in the voltage divider resistor parameters.

[0035] S6: If any of load 2 or load 3 has a load abnormality, it can be disconnected through load switch 2 or load switch 3 to ensure that the other load circuits work normally. In addition, the voltage difference change of the sampling resistor Rs can be used to determine which load has an abnormality, which is convenient for locating the fault point.

[0036] According to a preferred embodiment, step S4 includes: when the power circuit begins to operate under load, load 2 and / or load 3 may be connected to the circuit. Furthermore, the connection states of load 2 and load 3 may include: load 2 on, load 3 off, load 2 off, load 3 on, load 2 and load 3 simultaneously on, and load 2 and load 3 simultaneously off. When the power circuit begins to operate under load, any of the above operating states will reflect different load currents and / or voltage differences across the sampling resistor Rs.

[0037] Preferably, when the power circuit starts to operate under load, the voltage difference reflected on the sampling resistor Rs in any of the above-mentioned states will be recorded by the MCU as a secondary sampling value. The MCU can calculate the difference between the secondary sampling value related to the potential difference between the two ends of the sampling resistor Rs in each working state and the initial sampling value, and calculate the actual increased load current ΔI based on the voltage difference Δu between the secondary sampling value and the initial sampling value in combination with the resistance R of the sampling resistor Rs.

[0038] According to a preferred embodiment, when any one of load 2 and load 3 has an abnormality, for example, the load abnormality may include: load 2 and / or load 3 is disconnected, at which time the load current in the circuit becomes smaller and the load voltage increases; load 2 and / or load 3 is overloaded or short-circuited, at which time the load current in the circuit becomes larger and the load voltage decreases. Regardless of which of the above abnormal situations occurs, the MCU can use the actual current or voltage value as a judgment basis to determine the specific load with the abnormality, and disconnect the load switch used to control the connection of the faulty load to ensure the normal operation of other loads.

[0039] Specifically, for example, after the power supply circuit starts to work with load, the MCU controls load switch 2 and load switch 3 to turn on. At this time, load 2 and load 3 are connected to the circuit, and the MCU records the voltage difference of the sampling resistor Rs at this moment as a secondary sampling value. Furthermore, when at least one of load 2 and load 3 is overloaded or short-circuited, compared with the state when load 2 and load 3 are working normally, or compared with the standard threshold voltage or current in the normal working state, the load current in the circuit becomes larger, and the load voltage decreases. At this time, the MCU determines that there is a load fault in the circuit.

[0040] Furthermore, when the MCU determines that there is a load fault in the circuit, since both load 2 and load 3 are connected to the circuit, the cause of the circuit abnormality may be the fault of load 2 or load 3, or both load 2 and load 3. The MCU can determine the specific faulty load based on the voltage change of the sampling resistor Rs at this time.

[0041] According to a preferred embodiment, when at least one of load 2 and load 3 is connected to the circuit and both are in normal operating state, the secondary sampled value reflected on the sampling resistor Rs is generally within a known and determined range. However, when at least one of load 2 and load 3 fails, the secondary sampled value reflected on the sampling resistor Rs will change. That is, the secondary sampled value reflected on the sampling resistor Rs will generally be higher or lower than the standard load voltage or threshold load voltage when load 2 and / or load 3 are operating normally.

[0042] Specifically, when a load fault occurs in a circuit, the MCU can determine the specific faulty load and its fault type by disconnecting the circuit containing any load and recording the secondary sampled value on the sampling resistor Rs at the same time, comparing it with the standard load voltage or threshold load voltage when load 2 or load 3 is operating normally. For example, if the MCU disconnects the circuit containing load 2 and load 3 is still connected to the circuit, if the secondary sampled value on the sampling resistor Rs is within the determined range of the standard load voltage or threshold load voltage when load 3 is operating normally, it indicates that load 3 is normal and the faulty load is load 2. As mentioned above, if the load voltage at the time of the circuit fault is greater than the standard load voltage or the load current is less than the standard load current, the fault type of load 2 is an open circuit; otherwise, the fault type of load 2 is a short circuit or overload. At this time, based on the load fault determination result, the MCU can disconnect the circuit containing the faulty load to ensure the normal operation of other loads.

[0043] In some preferred embodiments, each load, i.e., load 2 and load 3, may be configured with corresponding load detection. When the MCU determines that there is a faulty load in the circuit based on the secondary sampling value on the sampling resistor Rs and the actual increased load current ΔI, the load detection of each load end may be started to obtain the operating voltage and / or current of each load end at the moment of the fault, and the specific faulty load may be determined based on the comparison result of the operating voltage and / or current of each load end with the standard threshold voltage and / or current, thereby controlling the corresponding load switch to be turned off.

[0044] In particular, the present invention autonomously calculates the actual load current by detecting the sampled voltage values ​​before and after the load is connected. At the same time, different load switches are designed in the circuit, so that abnormal loads can be cut off autonomously and controllably.

[0045] According to a preferred embodiment, the above-mentioned MCU can be of different models, through a field programmable gate array FPGA (Field-Programmable Gate Array) or a complex programmable logic device CPLD (Complex Programmable Logic Device). Preferably, the computing unit can also be a general-purpose central processing unit CPU (Central Processing Unit), an application-specific integrated circuit ASIC (Application Specific Integrated Circuit), a microprocessor or one or more integrated circuits and other components to execute relevant instructions or programs to implement the technical solution of the present invention. The present invention does not limit the specific type of device used in the computing unit, which depends on the actual situation. The MCU is used to execute the above-mentioned method according to the instructions. It should be noted that the above-mentioned components only show the components required for the specific embodiments of the present invention, such as the MCU, and do not mean that the remaining components for the normal operation of the present invention are not included.

[0046] For ease of understanding, the working principle and usage method of a power supply adaptive load detection and protection circuit of the present invention are discussed.

[0047] 1. First, add load switch 1 and sampling resistor Rs to the existing power supply output terminal C1. A differential sampling amplifier circuit is connected in parallel across sampling resistor Rs. This differential sampling amplifier circuit consists of voltage-divider resistors R1, R2, R3, and R4 and operational amplifier Op1. Op1's output signal is fed back to the MCU. Next, sampling resistor Rs is connected to load switches 2 and 3, which are then connected to loads 2 and 3, respectively. Before the power supply circuit operates under load, load switches 2 and 3 are off. At this point, load switch 1 is turned on. Due to the presence of the differential sampling amplifier circuit in the circuit, a certain voltage difference will appear across Rs. This voltage difference is fed back to the MCU through the differential sampling amplifier circuit and recorded as the initial sampling value. After the power supply circuit operates under load, load switches 2 and 3 are turned on. Loads 2 and 3 are connected to the circuit, the load current increases, and the voltage difference across Rs increases. This new voltage difference is fed back to the MCU and recorded as the secondary sampling value. The MCU calculates the difference between the secondary sampling value and the initial sampling value, and calculates the obtained voltage difference with Rs.

[0048] In the above manner, the load current is detected by differential calculation, and the MCU automatically calculates the load current to avoid deviations in the detection results due to differences in electronic component parameters. Since differential calculation is performed, the calculation results are not affected by differences in the voltage divider resistor parameters.

[0049] 2. Load switch 1 can be controlled on and off by the MCU. Load switch 2 and load switch 3 can also be controlled on and off by the MCU.

[0050] In this way, load operation is controlled by the load switch, which disconnects abnormal loads and ensures the overall stability of the power system. If either load 2 or load 3 experiences a load anomaly, it can be disconnected via load switch 2 or load switch 3, ensuring the normal operation of the other load circuits. The voltage difference across Rs can also be used to determine which load circuit has the anomaly, facilitating fault location.

[0051] Throughout the text, the features referred to as “preferably” are merely optional and should not be understood as having to be set. Therefore, the applicant reserves the right to abandon or delete the relevant preferred features at any time.

[0052] It should be noted that the above-mentioned specific embodiments are exemplary, and those skilled in the art can come up with various solutions inspired by the disclosure of the present invention, and these solutions also fall within the scope of the disclosure of the present invention and fall within the scope of protection of the present invention. Those skilled in the art should understand that the present invention specification and its drawings are illustrative and do not constitute a limitation on the claims. The scope of protection of the present invention is defined by the claims and their equivalents. The present invention specification contains multiple inventive concepts, such as "preferably", "according to a preferred embodiment" or "optionally", which means that the corresponding paragraph discloses an independent concept, and the applicant reserves the right to file a divisional application based on each inventive concept.

Claims

1. A power supply adaptive load detection and protection circuit, characterized in that: At least: a first load switch connected in series to an output terminal of the power supply; a sampling resistor Rs, connected in series to the output end of the first load switch; a differential sampling amplifier circuit connected in parallel to both ends of the sampling resistor Rs to receive and transmit a voltage difference between both ends of the sampling resistor Rs; At least one second load switch connected in parallel to the output end of the sampling resistor Rs, wherein the output end of the at least one second load switch is connected in series with at least one second load; An MCU capable of controlling the on / off of at least one first load switch and / or second load switch based on the output signal of the differential sampling and amplifying circuit, calculating the difference between the secondary sampling signal and the initial sampling signal to obtain a voltage difference Δu and an actual increased load current ΔI, determining whether a load abnormality exists in the circuit based on changes in the values ​​of the voltage difference Δu and / or the actual increased load current ΔI, and controlling the on / off of the corresponding second load switch when any second load exhibits an abnormality; When a load fault occurs in the circuit, the MCU disconnects the loop where any load is located and records the secondary sampling signal on the sampling resistor Rs at the same time. When the MCU determines that there is a faulty load in the circuit based on the secondary sampling value on the sampling resistor Rs and the actual increased load current ΔI, it starts load detection at each load end to obtain the operating voltage and / or current of each load end at the time of the fault. The specific faulty load and its fault type are determined by comparing and calculating the voltage and / or current with the standard load voltage or threshold load voltage when load 2 or load 3 is working normally, thereby controlling the corresponding load switch to be turned off.

2. A load detection method based on the circuit according to claim 1, characterized in that: The method comprises: The MCU records the voltage signal representing the voltage difference between the two ends of the sampling resistor Rs output by the differential sampling amplifier circuit before the power circuit starts to work under load as the initial sampling signal; The MCU records the voltage signal representing the voltage difference between the two ends of the sampling resistor Rs output by the differential sampling amplifier circuit after the power circuit starts to work under load as a secondary sampling signal; The MCU calculates the difference between the secondary sampling signal and the initial sampling signal to obtain a voltage difference Δu, and calculates the actual increased load current ΔI based on the voltage difference Δu and the resistance value of the sampling resistor Rs.

3. The load detection method according to claim 2, characterized in that: The MCU determines whether there is a load abnormality in the circuit according to the value change of the voltage difference Δu and / or the actual increased load current ΔI, including the following steps: When either the voltage difference Δu and / or the actually increased load current ΔI is not within the threshold range of the standard load voltage and / or current, the MCU determines that there is a load abnormality in the circuit.

4. The load detection method according to claim 3, characterized in that: When the MCU determines that there is a load abnormality in the circuit based on the voltage difference Δu and / or the actual increased load current ΔI, it can determine the circuit where the abnormal load is located based on the comparison result between the sampled voltage and / or current of the sampling resistor Rs when any second load is connected and the standard threshold voltage and / or current.

5. The load detection method according to claim 2, characterized in that: The differential sampling and amplifying circuit includes a plurality of voltage-dividing resistors and at least one operational amplifier.

6. The load detection method according to claim 2, characterized in that: The state of the power supply circuit before starting to work with load is: the first load switch is in the on state, and the second load switch is in the off state, and no second load is connected to the circuit.

7. The load detection method according to claim 2, characterized in that: The state of the power supply circuit after starting to work with load is: the first load switch is in the on state, and at least one second load switch is in the on state, and at least one second load is connected to the circuit.

8. The load detection method according to claim 2, characterized in that: The abnormal load state includes at least one of a second load disconnection, overload, and short circuit.

9. The load detection method according to claim 8, characterized in that: The overload and short circuit of the second load are manifested as an increase in the load current and / or a decrease in the load voltage associated with the sampling resistor Rs, and the disconnection of the second load is manifested as a decrease in the load current and / or an increase in the load voltage associated with the sampling resistor Rs.

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