Overvoltage, overcurrent, maximum voltage and maximum current protection circuit

Abstract

The utility model relates to an overvoltage, overcurrent, maximum voltage and maximum current protection circuit, which comprises the following four groups of protection detection circuits: a VREF signal, a Usample signal, resistors R1 and R2, and diodes D1 and D2 form a maximum voltage detection circuit; an overvoltage protection detection circuit is formed by the Uprogram signal, the Usample signal, a resistor R3, a resistor R4, a diode D3 and a diode D4. The VREF, an Isample signal, resistors R7 and R8, and diodes D7 and D8 form a maximum current detection circuit; and an over-current protection detection circuit is formed by an Iprogram signal, an Isample signal, a resistor R5, a resistor R6, a diode D5 and a diode D6. When a protection value is exceeded, the circuit immediately triggers a protection action and closes load output.

Description

Technical Field

[0001] The utility model relates to an electronic load for testing power supplies and electronic equipment, in particular to an overvoltage, overcurrent, maximum voltage and maximum current protection circuit. Background Art

[0002] Electronic loads are a key device used to test power supplies and electronic devices, and are widely used to test the performance of power modules, chargers, batteries, and other electronic devices. In practical applications, electronic loads must handle a variety of voltage, current, and power conditions. Therefore, ensuring they have overvoltage, overcurrent, and maximum current protection is crucial for ensuring test safety and device reliability.

[0003] The maximum voltage of an electronic load refers to the highest input voltage it can withstand. Exceeding this value may cause damage or failure of internal components. The maximum current of an electronic load refers to the maximum current it can absorb, which is generally determined by the capabilities of the device's internal power devices and cooling system. These two parameters directly determine the range of devices and application scenarios that the electronic load can test. To protect both the electronic load and the device under test, electronic loads are often equipped with overvoltage and overcurrent protection. These protection mechanisms can quickly respond to abnormal conditions and prevent device damage.

[0004] In previous DC electronic load designs, achieving maximum output voltages typically relied on high-voltage, high-current components and often employed a single protection mechanism. However, with the increasing complexity and diversity of electronic devices, existing electronic loads must not only handle higher voltages, currents, and power levels, but also require fast-response overvoltage and overcurrent protection to prevent damage to the device caused by abnormal conditions during testing. Therefore, developing a circuit design that can comprehensively handle overvoltage, overcurrent, and maximum voltage and current protection is crucial.

[0005] Technical solutions of existing technology:

[0006] Existing DC electronic load protection mechanisms often utilize separate protection circuits for voltage and current. These circuits process the collected voltage and current signals separately and send them to a single-chip microcontroller (MCU). The system then determines whether the current voltage and current values ​​exceed the corresponding protection settings. The results are then transmitted to the control circuit for execution. If these values ​​are exceeded, the appropriate protection action is triggered, such as current limiting or load shutdown.

[0007] Disadvantages of existing technology:

[0008] Protection mechanisms that process voltage and current separately require real-time data collection to be sent to a single-chip microcontroller for evaluation. To ensure high accuracy and reliability of the protection circuit, high-speed, high-precision chips are often used for data collection, increasing system design costs. Furthermore, this protection mechanism requires supporting hardware circuitry, which not only complicates the circuitry but also introduces a certain degree of protection delay.

[0009] In some cases, to protect electronic loads and test equipment from damage, the load output must be shut down immediately once a protection action is triggered, requiring the protection circuit to respond quickly. In these cases, it doesn't matter which protection circuit is triggered; the only requirement is that the load output shutdown action be quickly transmitted to the control circuit.

[0010] Therefore, from the perspective of design cost and rapid response protection action, this protection mechanism of first collecting data and then processing it through the microcontroller is not the optimal solution and needs further optimization.

[0011] In view of this, the present utility model is proposed. Utility Model Content

[0012] The purpose of the utility model is to provide an overvoltage, overcurrent, maximum voltage and maximum current protection circuit to solve the above technical problems existing in the prior art.

[0013] The purpose of this utility model is achieved through the following technical solutions:

[0014] The overvoltage, overcurrent, maximum voltage, and maximum current protection circuit of the present invention includes the following four groups of protection detection circuits:

[0015] VREF, U_sample signal, resistors R1, R2, and diodes D1, D2 form a maximum voltage detection circuit;

[0016] The U_protect and U_sample signals, as well as resistors R3 and R4, and diodes D3 and D4, form an overvoltage protection detection circuit;

[0017] VREF, I_sample signal, resistors R7, R8, and diodes D7, D8 form a maximum current detection circuit;

[0018] The I_protect and I_sample signals, resistors R5 and R6, and diodes D5 and D6 form an overcurrent protection detection circuit.

[0019] Compared with the existing technology, the overvoltage, overcurrent, maximum voltage and maximum current protection circuits provided by the utility model can judge in real time whether the voltage and current signals exceed the maximum value and the corresponding voltage and current protection setting values; when the protection value is exceeded, the protection action is immediately triggered and the load output is turned off. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The figure is a schematic diagram of the working principle of the protection circuit of the embodiment of the utility model in a DC electronic load system.

[0021] Figure 2 This is a schematic diagram of a protection circuit according to an embodiment of the present invention. DETAILED DESCRIPTION

[0022] The following is a clear and complete description of the technical solutions in the embodiments of the present invention, in conjunction with the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them, and do not constitute a limitation of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0023] First, the following terms may be used in this article:

[0024] The term “and / or” means that either or both of them can be realized at the same time. For example, X and / or Y includes both “X” or “Y” and “X and Y”.

[0025] The terms "include," "comprises," "contains," "has," or other similar expressions should be interpreted as non-exclusive. For example, "including certain technical features (such as raw materials, components, ingredients, carriers, dosage forms, materials, dimensions, parts, components, mechanisms, devices, steps, procedures, methods, reaction conditions, processing conditions, parameters, algorithms, signals, data, products, or manufactured articles, etc.) should be interpreted as including not only the technical features explicitly listed, but also other technical features known in the art that are not explicitly listed.

[0026] The term "consisting of" excludes any technical features not explicitly listed. If used in a claim, this term renders the claim closed, excluding any technical features other than those explicitly listed, except for conventional impurities associated with them. If this term appears only in a clause of a claim, it limits only the elements explicitly listed in that clause; elements listed in other clauses are not excluded from the claim as a whole.

[0027] Unless otherwise specified or limited, the terms "mounted," "connected," "connect," and "fixed" should be interpreted broadly. For example, they can refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediary; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in this document based on specific circumstances.

[0028] The terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings and are only for the convenience and simplification of description, and do not explicitly or implicitly indicate that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be understood as a limitation to this document.

[0029] The contents not described in detail in the examples of this utility model belong to the prior art known to those skilled in the art. If specific conditions are not specified in the examples of this utility model, the experiments were carried out according to conventional conditions in the art or the conditions recommended by the manufacturer. If the manufacturers of the reagents or instruments used in the examples of this utility model are not specified, they are all conventional products that can be purchased commercially.

[0030] The overvoltage, overcurrent, maximum voltage, and maximum current protection circuit of the present invention includes the following four groups of protection detection circuits:

[0031] VREF, U_sample signal, resistors R1, R2, and diodes D1, D2 form a maximum voltage detection circuit;

[0032] The U_protect and U_sample signals, as well as resistors R3 and R4, and diodes D3 and D4, form an overvoltage protection detection circuit;

[0033] VREF, I_sample signal, resistors R7, R8, and diodes D7, D8 form a maximum current detection circuit;

[0034] The I_protect and I_sample signals, resistors R5 and R6, and diodes D5 and D6 form an overcurrent protection detection circuit.

[0035] In the maximum voltage detection circuit, R1 is connected to VREF and the anode of D1, R2 is connected to U_sample and the cathode of D1, and the cathode of D1 is connected to the cathode of D2;

[0036] In the overvoltage protection detection circuit, R3 is connected to U_sample and the cathode of D3, R4 is connected to U_protect and the anode of D3, and the cathode of D3 is connected to the cathode of D4;

[0037] In the maximum current detection circuit, R7 is connected to I_sample and the cathode of D7, R8 is connected to VREF and the anode of D7, and the cathode of D7 is connected to the cathode of D8;

[0038] In the overcurrent protection detection circuit, R5 is connected to I_protect and the anode of D5, R6 is connected to I_sample and the cathode of D5, and the cathode of D5 is connected to the cathode of D6.

[0039] Diodes D2, D4, D6, and D8 connect the four sets of protection detection circuits to the input terminals of operational amplifier U1.

[0040] The anodes of D2, D4, D6, and D8 are connected together to form a common node, which is connected to the non-inverting input terminal of the operational amplifier U1 through the resistor R9. The resistor R9 is the input protection resistor of the operational amplifier U1.

[0041] Capacitor C1 is connected to the non-inverting input terminal of the operational amplifier U1 and resistor R10, and the other end of the resistor R10 is connected to the output terminal of the operational amplifier U1;

[0042] The anode of the voltage regulator tube D9 is connected to the non-inverting input terminal of the operational amplifier U1, and the cathode is connected to the output terminal of the operational amplifier U1;

[0043] VCC and VEE are connected to the positive and negative power supply terminals of op amp U1 respectively;

[0044] The inverting input of op amp U1 is grounded.

[0045] The DC electronic load system where the protection circuit is located includes:

[0046] The MCU, DAC, protection circuit, control unit, protection execution unit, acquisition unit, and ADC are connected in sequence, and the ADC is connected to the MCU;

[0047] The acquisition unit is connected to the protection circuit, and the control unit is connected to the MCU.

[0048] In summary, the overvoltage, overcurrent, and maximum voltage and current protection circuits of the present invention determine in real time whether voltage and current signals exceed their maximum values ​​and corresponding voltage and current protection settings. When these values ​​are exceeded, protection is immediately triggered, shutting down the load output. This not only reduces design costs but also improves the response speed and reliability of the protection mechanism, achieving high speed and precision.

[0049] In order to more clearly demonstrate the technical solutions and technical effects provided by the present invention, the embodiments of the present invention are described in detail below with reference to specific embodiments.

[0050] Example 1

[0051] 1. First, the working principle of the protection circuit of the present invention in the DC electronic load system is introduced. Figure 1 shown.

[0052] The protection circuit first receives the real-time voltage signal and current signal from the acquisition unit, as well as the voltage protection setting value and current protection setting value transmitted by the DAC; then it determines whether the current voltage value and current value exceed the set protection value and maximum value; and then transmits the judgment result to the control unit; if protection measures need to be taken, the protection execution unit will perform the protection action.

[0053] It is mainly divided into seven parts, and the functions of each part are as follows:

[0054] (1) MCU: In the protection system, the MCU mainly processes the voltage and current digital quantities transmitted by the ADC for human-computer interaction, and transmits the set protection value digital quantity to the DAC;

[0055] (2) DAC: Converts the voltage and current protection values ​​set in the MCU from digital to analog and transmits them to the protection circuit;

[0056] (3) ADC: converts the real-time voltage, current and other signals transmitted by the acquisition unit from analog to digital and transmits them to the MCU;

[0057] (4) Protection circuit: detects whether protection action needs to be executed based on the current voltage, current value and protection setting value, and transmits the judgment result to the control unit;

[0058] (5) Control unit: performs corresponding control actions according to the judgment results of the protection circuit. If the protection is triggered, the instruction is transmitted to the protection execution unit and the alarm information is transmitted to the MCU;

[0059] (6) Protection execution unit: operates according to the instructions transmitted by the control unit and determines whether to initiate the protection action;

[0060] (7) Acquisition circuit: converts real-time voltage and current signals into analog signals that can be used for protection circuits and ADCs;

[0061] The protection circuit of the present invention is as follows Figure 2 shown.

[0062] Figure 2The diodes in the circuit are all devices of the same model; U_sample and I_sample are the current voltage and current sampling values, which are negative signals and come from the real-time signals transmitted by the acquisition circuit; U_protect and I_protect are the set voltage and current protection values, which are positive signals and are set by the user and converted by the MCU and DAC; the VREF signal is a fixed voltage reference signal, which is the voltage reference of the maximum voltage and maximum current protection points and is a positive signal; Uo is the protection circuit result indication signal.

[0063] Figure 2 If the polarity of each signal in the circuit design is inconsistent with the actual circuit, the polarity can be adjusted using the reverse amplifier circuit. I will not repeat it here. The default polarity of each signal in the system is consistent with Figure 2 The Chinese are consistent.

[0064] In the figure, R1 is connected to VREF and the anode of D1, R2 is connected to U_sample and the cathode of D1, and the cathode of D1 is connected to the cathode of D2. VREF, U_sample, resistors R1 and R2, and diodes D1 and D2 form the maximum voltage detection circuit. R3 is connected to U_sample and the cathode of D3, R4 is connected to U_protect and the anode of D3, and the cathode of D3 is connected to the cathode of D4. U_protect, U_sample, resistors R3 and R4, and diodes D3 and D4 form the overvoltage protection detection circuit. R7 is connected to I_sample and the cathode of D7, R8 is connected to VREF and the anode of D7, and the cathode of D7 is connected to the cathode of D8. VREF, I_sample, resistors R7 and R8, and diodes D7 and D8 form the maximum current detection circuit. R5 is connected to the anode of I_protect and D5, R6 is connected to the cathode of I_sample and D5, and the cathode of D5 is connected to the cathode of D6. The I_protect and I_sample signals, as well as resistors R5 and R6, and diodes D5 and D6 form an overcurrent protection detection circuit.

[0065] The maximum voltage detection circuit composed of the U_sample signal and the VREF signal is calculated as a single input. The two diodes D1 and D2 are ignored. The voltage divider effect of the two signals through the resistors R1 and R2 determines the output result of the operational amplifier U1.

[0066] Input voltage of op amp U1:

[0067] Ui=VREF-(VREF-U_sample)×[R1 / (R1+R2)]

[0068] =[R2 / (R1+R2)]×VREF+[R1 / (R1+R2)]×U_sample

[0069] When the Ui signal is negative, the output of the op amp U1 is stabilized at a fixed voltage, namely the breakdown voltage Uz of the voltage regulator D9, due to the action of the voltage regulator D9; when the Ui signal is positive, the output Uo of the op amp U1 is close to zero.

[0070] Based on the operating principle of the above circuit, with the fixed voltage VREF as the benchmark, according to different electronic load models and design scenarios, once the maximum voltage value that triggers the protection of the electronic load is determined, the resistance values ​​of resistors R1 and R2 can be determined by calculation.

[0071] Once the VREF voltage reference signal and the values ​​of resistors R1 and R2 are determined, the maximum voltage protection value is also fixed. In other words, once the real-time voltage acquisition signal exceeds the maximum voltage value, the Uo output is the breakdown voltage value Uz of the voltage regulator; otherwise, the Uo output is zero.

[0072] The maximum current detection circuit operates on the same principle. The overvoltage and overcurrent protection detection circuits differ from the maximum detection circuit in that they use the voltage and current protection settings transmitted by the DAC as a voltage reference. During electronic load operation, these protection settings are typically not dynamically changing voltages. Instead, they are set by the user through human-computer interaction and transmitted to the DAC via the MCU. Therefore, until the user sets a new protection value, the voltage and current protection settings are considered fixed. Therefore, the operating principles of the overvoltage and overcurrent protection detection circuits are similar to those of the maximum detection circuit and will not be repeated here.

[0073] Figure 2 The anodes of D2, D4, D6, and D8 are connected together to form a common node, which is connected to the non-inverting input terminal of the operational amplifier U1 through the resistor R9; that is, the diodes D2, D4, D6, and D8 connect the four groups of protection detection circuits to the input terminal of the operational amplifier U1, so that no matter which group of circuits detects that the set value or the maximum value is exceeded, the output result Uo of the operational amplifier U1 can change accordingly.

[0074] Diodes D1, D3, D5, and D7 eliminate the effect of the voltage drop across diodes D2, D4, D6, and D8 on the resistor value calculations in the voltage divider circuit, thus preventing unnecessary errors. Due to the presence of diodes D1, D3, D5, and D7, zero can be used as the trigger point for protection when calculating the resistor values ​​in each set of protection detection circuits.

[0075] Capacitor C1 is connected to the non-inverting input of op amp U1 and resistor R10. The other end of resistor R10 is connected to the output of op amp U1. The anode of voltage regulator D9 is connected to the non-inverting input of op amp U1, and the cathode is connected to the output of op amp U1. VCC and VEE are connected to the positive and negative power supply terminals of op amp U1, respectively. The inverting input of op amp U1 is grounded. Resistor R9 serves as the input protection resistor of op amp U1. Capacitor C1, resistor R10, and voltage regulator D9 allow the output signal of op amp U1 to directly act as the activation signal for protection actions in the control circuit.

[0076] The beneficial effects brought about by the technical solution of the present invention are:

[0077] The present invention provides a hardware circuit for simultaneous detection and protection of overvoltage, overcurrent, maximum voltage, and maximum current, wherein software is only involved in setting the overvoltage and overcurrent protection values. Therefore, a fast-response, high-precision protection mechanism can be implemented without the need for high-speed, high-precision ADCs and DACs. In terms of design cost, there are no high-cost components, and the components used in the protection circuit are simple and can be adjusted and replaced according to different design requirements, greatly reducing design and manufacturing costs. In terms of response speed, the hardware protection circuit is integrated on the circuit board and can respond quickly within nanoseconds to microseconds, preventing damage to the equipment caused by abnormal conditions of the electronic load during testing. Furthermore, the protection circuit is not easily affected by the software system and is simple in design and can operate in environments with certain temperature and humidity, providing higher reliability and stability.

[0078] Key technical points of the present invention:

[0079] (1) The composition of the voltage divider resistors (e.g., R1, R2) and the compensation diodes (e.g., D1, D2) in each set of protection detection circuits;

[0080] (2) Overvoltage and overcurrent protection hardware detection circuit, using DAC chip to transmit protection point voltage reference that can change with the protection setting value;

[0081] (3) Diodes D2, D4, D6, and D8 form four groups of protection modes, and any one of them can respond quickly when triggered.

[0082] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims. The information disclosed in the background technology section of this article is only intended to deepen the understanding of the overall background technology of the present invention, and should not be regarded as an admission or any form of implication that the information constitutes prior art already known to those skilled in the art.

Claims

1. An overvoltage, overcurrent, maximum voltage, and maximum current protection circuit, characterized in that: The protection circuit includes the following four groups of protection detection circuits: VREF, U_sample signal, resistors R1, R2, and diodes D1, D2 form a maximum voltage detection circuit; The U_protect and U_sample signals, as well as resistors R3 and R4, and diodes D3 and D4, form an overvoltage protection detection circuit; VREF, I_sample signal, resistors R7, R8, and diodes D7, D8 form a maximum current detection circuit; The I_protect and I_sample signals, resistors R5 and R6, and diodes D5 and D6 form an overcurrent protection detection circuit.

2. The overvoltage, overcurrent, maximum voltage, and maximum current protection circuit according to claim 1, characterized in that: In the maximum voltage detection circuit, R1 is connected to VREF and the anode of D1, R2 is connected to U_sample and the cathode of D1, and the cathode of D1 is connected to the cathode of D2; In the overvoltage protection detection circuit, R3 is connected to U_sample and the cathode of D3, R4 is connected to U_protect and the anode of D3, and the cathode of D3 is connected to the cathode of D4; In the maximum current detection circuit, R7 is connected to I_sample and the cathode of D7, R8 is connected to VREF and the anode of D7, and the cathode of D7 is connected to the cathode of D8; In the overcurrent protection detection circuit, R5 is connected to I_protect and the anode of D5, R6 is connected to I_sample and the cathode of D5, and the cathode of D5 is connected to the cathode of D6.

3. The overvoltage, overcurrent, maximum voltage, and maximum current protection circuit according to claim 2, characterized in that: Diodes D2, D4, D6, and D8 connect the four sets of protection detection circuits to the input terminals of operational amplifier U1.

4. The overvoltage, overcurrent, maximum voltage, and maximum current protection circuit according to claim 3, characterized in that: The anodes of D2, D4, D6, and D8 are connected together to form a common node, which is connected to the non-inverting input terminal of the operational amplifier U1 through the resistor R9. The resistor R9 is the input protection resistor of the operational amplifier U1.

5. The overvoltage, overcurrent, maximum voltage, and maximum current protection circuit according to claim 4, characterized in that: Capacitor C1 is connected to the non-inverting input terminal of the operational amplifier U1 and resistor R10, and the other end of the resistor R10 is connected to the output terminal of the operational amplifier U1; The anode of the voltage regulator tube D9 is connected to the non-inverting input terminal of the operational amplifier U1, and the cathode is connected to the output terminal of the operational amplifier U1; VCC and VEE are connected to the positive and negative power supply terminals of op amp U1 respectively; The inverting input of op amp U1 is grounded.

6. The overvoltage, overcurrent, maximum voltage, and maximum current protection circuit according to any one of claims 1 to 5, characterized in that: The DC electronic load system where the protection circuit is located includes: The MCU, DAC, protection circuit, control unit, protection execution unit, acquisition unit, and ADC are connected in sequence, and the ADC is connected to the MCU; The acquisition unit is connected to the protection circuit, and the control unit is connected to the MCU.

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