An adjustable hardware overvoltage, overcurrent protection circuit

Abstract

The utility model discloses an adjustable hardware overvoltage, overcurrent protection circuit, including micro control unit, digital analog converter, double operational amplifier and double channel comparator. Micro control unit sends digital instruction to digital analog converter through serial communication interface, and digital analog converter output corresponding analog reference voltage generates negative reference voltage after inverting amplification through operational amplifier, and generates positive reference voltage after inverting amplification through another operational amplifier again, and the signal is input to double channel comparator, and compares with positive reference voltage and negative reference voltage respectively, and if the detection signal is over the set threshold range, then the comparator output protection signal, trigger system protection mechanism. The utility model has threshold value software adjustable, response speed is fast, parameter power failure preservation, multi -model adaptation and so on advantage, is applicable to frequency converter, servo driver, electric automobile controller and so on motor drive system's real -time overvoltage, overcurrent protection, has improved the reliability and flexibility of system obviously.

Description

Technical Field

[0001] This utility model relates to overvoltage and overcurrent protection circuits, and more particularly to an adjustable hardware overvoltage and overcurrent protection circuit. Background Technology

[0002] In motor control systems, overvoltage and overcurrent protection are key technologies to ensure the safe operation of power devices (such as IGBTs) and the system. Traditional protection schemes mainly fall into two categories: one is a purely hardware scheme, using a comparator with a fixed threshold. While this offers a fast response, the threshold is not adjustable, requiring resistor replacement to adapt to different models, resulting in poor flexibility. The other is a purely software scheme, where the MCU samples the data and then the software makes the judgment. Although the threshold is adjustable, the response speed is slow, typically greater than 10μs, making it unable to handle transient faults such as short circuits, and there is a risk of program overload leading to protection failure.

[0003] Furthermore, when adapting to multiple models, traditional solutions require the preparation of various hardware materials, increasing inventory costs and production complexity; threshold parameters are lost after power failure, making them prone to false triggering upon power-up; under extreme conditions, such as the IGBT short-circuit withstand time of only 10μs, software delays lead to untimely protection and a high failure rate. Therefore, there is an urgent need for a protection circuit that combines flexibility, high speed, and reliability. Utility Model Content

[0004] To address the shortcomings of the aforementioned technologies, this invention provides an adjustable hardware overvoltage and overcurrent protection circuit.

[0005] To solve the above technical problems, the technical solution adopted by this utility model is: an adjustable hardware overvoltage and overcurrent protection circuit, comprising: The microcontroller unit is used to generate and output digital instructions for threshold configuration; A digital-to-analog converter, whose digital input is connected to a microcontroller unit, receives digital commands and converts them into an analog reference voltage output; The first operational amplifier has its inverting input terminal connected to the output terminal of the digital-to-analog converter through a first resistor, forming an inverting voltage follower that outputs a negative reference voltage. The second operational amplifier has its inverting input terminal connected to the output terminal of the first operational amplifier through a second resistor, forming an inverting voltage follower that outputs a positive reference voltage. A dual-channel comparator includes a first comparator and a second comparator; the non-inverting input of the first comparator is connected to a positive reference voltage, and the inverting input is connected to the signal to be detected; the inverting input of the second comparator is connected to a negative reference voltage, and the non-inverting input is connected to the signal to be detected. When the signal to be detected is greater than the positive reference voltage or less than the negative reference voltage, the first comparator or the second comparator outputs a low level, triggering the protection signal output.

[0006] Furthermore, the digital-to-analog converter is connected to the microcontroller unit via a serial communication interface, which includes a serial clock line and a serial data line.

[0007] Furthermore, the non-inverting input terminals of the first operational amplifier and the second operational amplifier are both grounded through resistors, and feedback resistors are connected between the inverting input terminal and the output terminal of the first operational amplifier and between the inverting input terminal and the output terminal of the second operational amplifier.

[0008] Furthermore, the first operational amplifier and the second operational amplifier are powered by a dual ±15V power supply.

[0009] Furthermore, the digital-to-analog converter is powered by a single +15V power supply, its reference voltage pin is grounded, and the output terminal is equipped with a filter and voltage regulator circuit to filter and regulate the output analog reference voltage.

[0010] This utility model has the following significant advantages: Extremely short response time: protection trigger time is less than 200 nanoseconds, which is more than 25 times faster than pure software solutions and can cope with transient faults; Flexible and adjustable threshold: The protection threshold can be changed by configuring parameters through software, without the need to replace hardware, adapting to the needs of multiple models and reducing inventory costs; Parameters are saved even after power failure: The DAC chip has a non-volatile memory function, which automatically restores the set parameters after restarting to avoid the loss of threshold values; The system has strong compatibility: it is suitable for various motor drive systems such as frequency converters, servo drives, and electric vehicle controllers; Easy upgrades and maintenance: Deployed products can have their parameters updated remotely via the communication interface without the need for hardware replacement, saving time and manpower costs. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the system structure of this utility model.

[0012] Figure 2 This is a partial circuit diagram of the present invention. Figure 1 .

[0013] Figure 3 This is a partial circuit diagram of the present invention. Figure 2 .

[0014] Figure 4 This is a partial circuit diagram of the present invention. Figure 3 .

[0015] Figure 5 This is a partial circuit diagram of the present invention. Figure 4 . Detailed Implementation

[0016] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0017] This utility model discloses an adjustable hardware overvoltage and overcurrent protection circuit, the system structure of which is as follows: Figure 1 As shown, the circuit includes a microcontroller unit (MCU), a digital-to-analog converter (DAC), and dual operational amplifiers OP1 (OP1 internally contains a first operational amplifier OP1A and a second operational amplifier OP1B). A dual-channel comparator U1 internally contains a first comparator U1A and a second comparator U1B. Threshold parameter commands are sent to the MCU (model U3) via SCLK and SDA. U3 outputs a corresponding reference voltage Vref. Vref is inverted and amplified by OP1A to become a negative reference voltage -Vref. This voltage is divided into two paths: one path is directly sent to the inverting input of U1B as a negative threshold; the other path is inverted and amplified by OP1B to become a positive reference voltage +Vref, which is sent to the non-inverting input of U1A as a positive threshold. The signal IN to be detected is simultaneously input to the inverting input of U1A and the non-inverting input of U1B via resistor R2. When the IN voltage exceeds +Vref or falls below -Vref, U1A or U1B outputs a low level, which, after being shaped by the output circuit, triggers the protection signal OUT. The entire process requires no real-time MCU involvement, with a response time of no more than 200 nanoseconds, which is much faster than software solutions of ≥5 microseconds. It can effectively cover the protection time window of <10 microseconds for transient faults such as IGBT short circuits, fundamentally solving the problem of machine failure caused by response delay in the background technology and significantly reducing the failure rate.

[0018] Specifically, such as Figure 3 and Figure 4 As shown, the MCU is connected to the input pins U3_1 and U3_2 of the DAC chip U3 via the serial clock line SCLK and the serial data line SDA, for sending threshold configuration commands. The power supply pin U3_4 of U3 is connected to +15V, and U3_5 is grounded (GND), forming a single power supply. Its output pin U3_6 is connected to the inverting input pin OP1A_2 of the operational amplifier OP1A via resistor R7. The reference voltage pin U3_7 of U3 is grounded, U3_8 is connected to U3_7 via capacitor C8, U3_9 is grounded, and capacitor C9 and voltage regulator U4 are connected in parallel between U3_6 and ground for output filtering and voltage regulation.

[0019] The inverting input OP1A_2 of operational amplifier OP1A is connected to the output of U3 via resistor R7, and the non-inverting input OP1A_3 is grounded via resistor R9. Feedback resistor R5 is connected between OP1A_2 and the output OP1A_1, forming an inverting voltage follower to invert Vref and output -Vref. The output OP1A_1 of OP1A is connected to the inverting input OP1B_6 of operational amplifier OP1B via resistor R8. The non-inverting input OP1B_5 of OP1B is grounded via resistor R10, and feedback resistor R6 is connected between OP1B_6 and the output OP1B_7, also forming an inverting voltage follower to invert -Vref and output +Vref.

[0020] The non-inverting input U1A_3 of the first comparator U1A is connected to the output OP1B_7 of OP1B to obtain +Vref; the inverting input U1A_2 is connected to the signal IN to be detected through resistor R2. The inverting input U1B_6 of the second comparator U1B is connected to the output OP1A_1 of OP1A to obtain -Vref; the non-inverting input U1B_5 is also connected to the IN signal through resistor R2. A capacitor C3 is connected in parallel between U1B_5 and ground for filtering. The outputs U1A_1 and U1B_7 of U1A and U1B are connected together and output a protection signal OUT through resistor R3. The OUT signal is connected to the power supply VDD through pull-up resistor R1 and grounded through diode D1 and capacitor C4, forming a signal shaping and anti-interference circuit.

[0021] In the entire circuit, operational amplifier OP1 and comparator U1 are powered by a dual ±15V power supply: For example Figure 5 As shown, the power supply pins OP1C_8 are connected to +15V, and OP1C_4 is connected to -15V; Figure 2 As shown, the power supply pins U1C_8 of U1 are connected to +15V, and U1C_4 is connected to -15V.

[0022] It should be noted that the dual-channel comparator U1 internally integrates two independent comparators, U1A and U1B. Each comparator determines its output state by comparing the voltages at its two input terminals: when the voltage at the non-inverting input is higher than that at the inverting input, the output is high; otherwise, the output is low. The dual operational amplifier OP1 internally integrates two op-amps, OP1A and OP1B. OP1A, together with resistors R5, R7, and R9, forms an inverting voltage follower, inverting the input Vref to -Vref; OP1B, together with resistors R6, R8, and R10, forms another inverting voltage follower, inverting -Vref to +Vref, while simultaneously improving the output load capacity and achieving voltage isolation and signal enhancement. The DAC chip U3 receives digital commands sent by the MCU through the serial interface, converts them into an analog voltage Vref output, and has parameter storage capabilities, which are not lost after power failure.

[0023] In summary, during the operation of the entire circuit, the MCU configures threshold parameters for U3 via the communication interfaces "SCLK" and "SDA". U3 saves the parameters and outputs the set voltage Vref. Vref is output as a negative voltage reference value via OP1A, and -Vref is then used as a positive voltage reference value via OP1B to generate +Vref. The positive voltage reference value +Vref is provided to U1A as the upper limit comparison value for triggering, and the negative voltage reference value -Vref is provided to U1B as the lower limit comparison value for triggering. The signal requiring protection enters through the IN pin and is input to both U1A and U1B. The signal input to U1A is compared with +Vref. If IN > +Vref, U1A will output a low level, and OUT will output a protection signal. The signal input to U1B is compared with -Vref. If IN < -Vref, U1B will output a low level, and OUT will output a protection signal. As long as the input signal IN is greater than or less than the set threshold, the OUT output protection signal will be triggered. When adjusting the protection threshold, no hardware parameters need to be changed. The MUC only needs to reconfigure the threshold parameters of U3 using "SCLK" and "SDA". For example, if the required protection threshold is ±3V, U3 only needs to be configured to output 3V to obtain -Vref voltage as -3V and +Vref voltage as +3V. The input signal IN will be compared with ±3V. If IN > +3V or IN < -3V, OUT will output a protection signal; if -3V < IN < +3V, OUT will not trigger a protection signal.

[0024] This invention allows for software-configurable thresholds, enabling adaptation to different overcurrent thresholds required by various inverter models, such as 22kW and 75kW inverters, without requiring any hardware replacement. This significantly improves production efficiency and system flexibility. Parameters are stored in the DAC chip and are retained even after power loss, avoiding the risk of accidental triggering upon power-up. For existing products, threshold updates can be completed within seconds via the communication interface, eliminating the need for production line shutdowns and hardware replacements, thus significantly saving maintenance costs and time.

[0025] Compared with traditional solutions, this utility model has the following significant advantages: Extremely short response time: protection trigger time is less than 200 nanoseconds, which is more than 25 times faster than pure software solutions and can cope with transient faults; Flexible and adjustable threshold: The protection threshold can be changed by configuring parameters through software, without the need to replace hardware, adapting to the needs of multiple models and reducing inventory costs; Parameters are saved even after power failure: The DAC chip has a non-volatile memory function, which automatically restores the set parameters after restarting to avoid the loss of threshold values; The system has strong compatibility: it is suitable for various motor drive systems such as frequency converters, servo drives, and electric vehicle controllers; Easy upgrades and maintenance: Deployed products can have their parameters updated remotely via the communication interface without the need for hardware replacement, saving time and manpower costs.

[0026] The above embodiments are not intended to limit the present utility model, nor is the present utility model limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the technical solution of the present utility model are also within the protection scope of the present utility model.

Claims

1. An adjustable hardware overvoltage and overcurrent protection circuit, characterized in that: The microcontroller unit is used to generate and output digital instructions for threshold configuration; A digital-to-analog converter, whose digital input is connected to a microcontroller unit, receives digital commands and converts them into an analog reference voltage output; The first operational amplifier has its inverting input terminal connected to the output terminal of the digital-to-analog converter through a first resistor, forming an inverting voltage follower that outputs a negative reference voltage. The second operational amplifier has its inverting input terminal connected to the output terminal of the first operational amplifier through a second resistor, forming an inverting voltage follower that outputs a positive reference voltage. A dual-channel comparator includes a first comparator and a second comparator; the non-inverting input of the first comparator is connected to a positive reference voltage, and the inverting input is connected to the signal to be detected; the inverting input of the second comparator is connected to a negative reference voltage, and the non-inverting input is connected to the signal to be detected. When the signal to be detected is greater than the positive reference voltage or less than the negative reference voltage, the first comparator or the second comparator outputs a low level, triggering the protection signal output.

2. The adjustable hardware overvoltage and overcurrent protection circuit according to claim 1, characterized in that: The digital-to-analog converter is connected to the microcontroller unit via a serial communication interface, which includes a serial clock line and a serial data line.

3. The adjustable hardware overvoltage and overcurrent protection circuit according to claim 1, characterized in that: The non-inverting input terminals of the first operational amplifier and the second operational amplifier are both grounded through resistors, and feedback resistors are connected between the inverting input terminal and the output terminal of the first operational amplifier and between the inverting input terminal and the output terminal of the second operational amplifier.

4. The adjustable hardware overvoltage and overcurrent protection circuit according to claim 1, characterized in that: The first operational amplifier and the second operational amplifier are powered by a dual ±15V power supply.

5. The adjustable hardware overvoltage and overcurrent protection circuit according to claim 1, characterized in that: The digital-to-analog converter is powered by a single +15V power supply. Its reference voltage pin is grounded, and the output terminal is equipped with a filter and voltage regulator circuit to filter and regulate the output analog reference voltage.

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