Threshold-adaptive wave-by-wave current-limiting protection circuit and method

Abstract

The invention discloses a threshold-adaptive wave-by-wave current-limiting protection circuit and method. The method comprises the following steps: S1, an output port of a controller generates a square wave signal with an adjustable duty ratio; s2, shaping the square wave signal into a standard square wave signal through a shaping circuit; s3, inputting the standard square wave signal into a low-pass filter circuit for filtering to obtain a direct-current voltage serving as a protection threshold value; s4, monitoring the temperature of a power device and the voltage of a system bus; s5, judging whether the output power of the system is changed or not within preset time; s6, if the output power does not change, calculating and updating a protection threshold value by adjusting the duty ratio of the square wave signal according to the current temperature of the power device and the current value of the bus voltage; and S7, if the output power changes, setting the protection threshold as a preset minimum value. The invention aims to realize self-adaptive adjustment of a wave-by-wave current-limiting protection threshold, so that the protection is more flexible and accurate, the method can adapt to different scenes, characteristics, aging and working condition changes, and the capacity waste of a power device and an energy storage converter is avoided.

Description

Technical Field

[0001] This invention relates to the field of power electronic equipment, and more particularly to a threshold-adaptive wave-by-wave current limiting protection circuit and method for energy storage converters. Background Technology

[0002] As the core equipment of new energy storage systems, energy storage converters are experiencing rapid technological upgrades and increasing demands for intelligence. Wavelength current limiting protection is an important protection feature in energy storage converters. It detects the reactor current and actively blocks the drive waveform of the power devices when the current exceeds a set protection threshold, preventing the power devices from being continuously turned on and thus preventing overcurrent damage to the power devices.

[0003] like Figure 1 This refers to existing wave-by-wave current limiting circuit schemes. The protection thresholds for wave-by-wave current limiting protection are typically obtained by dividing a hardware reference voltage into an upper fixed voltage V1 and a lower fixed voltage V2. The circuit for fixing the protection voltage threshold is shown in [link to circuit]. Figure 2 When the control circuit detects that the reactor current is greater than V1 or less than V2, it triggers wave-by-wave current limiting protection, blocking the power device from generating waves. However, the fixed protection threshold mode also has a series of application problems: facing complex and ever-changing application scenarios and grid characteristics, the fixed protection threshold is inflexible and may result in situations where faults are not protected or false protection occurs; the fixed protection threshold cannot be dynamically adjusted according to actual operating data and cannot adapt to long-term equipment aging or changes in operating conditions; generally, the upper limit of the protection threshold is constrained by the most severe thermal and stress conditions of the power device. If the equipment operates under non-extreme conditions for a long time, designing the protection threshold according to the most severe conditions is also a waste of the power device and energy storage converter capacity. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a threshold-adaptive wave-by-wave current limiting protection circuit and method. Its purpose is to achieve adaptive adjustment of the wave-by-wave current limiting protection threshold, making the protection more flexible and accurate, and adaptable to different application scenarios, power grid characteristics, equipment aging and changes in operating conditions, thereby avoiding the waste of power devices and energy storage converter capabilities.

[0005] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution: According to a first aspect of the present invention, a threshold-adaptive wave-by-wave current limiting protection method is provided, comprising the following steps: S1. A square wave signal is generated through the output port of the controller, and the duty cycle of the square wave signal is adjustable; S2. Input the square wave signal into the shaping circuit for shaping to obtain a standard square wave signal; S3. The standard square wave signal is input to a low-pass filter circuit for filtering to obtain a DC voltage, which is used as the protection threshold for wave-by-wave current limiting protection. S4. Monitor the temperature of power devices and the bus voltage of the system; S5. Determine whether the output power of the system changes within a predetermined time period; S6. If the output power does not change within a predetermined time, the protection threshold is calculated and updated based on the current temperature of the power device and the current value of the bus voltage. S7. If the output power changes within a predetermined time, the protection threshold is set to a preset minimum value. In step S6, the updated protection threshold is achieved by adjusting the duty cycle of the square wave signal.

[0006] In one possible implementation of the first aspect, the shaping circuit includes a Schmitt trigger or an analog switch.

[0007] In one possible implementation of the first aspect, the predetermined time is 2 to 4 minutes.

[0008] In one possible implementation of the first aspect, in step S6, when calculating the protection threshold based on the current temperature of the power device and the current value of the bus voltage, the calculation is performed based on an adaptive function relationship, which is established in the following manner: First, with the power device temperature fixed, the power device current is constrained by the voltage stress specification of the power device to obtain the functional relationship between the power device current and the bus voltage that satisfies the stress. Then, the temperature of the power device is extended to the entire operating temperature range to obtain the objective function relationship; Finally, based on the sampling coefficient of the power device current by the controller, the objective function relationship is converted into a function relationship between the protection threshold voltage and the power device temperature and the bus voltage.

[0009] In one possible implementation of the first aspect, the objective function relationship is I=F(T, U, I), where I represents the power device current, T represents the power device temperature, and U represents the bus voltage.

[0010] In one possible implementation of the first aspect, when converting the target function relationship into a function of the protection threshold voltage V, the conversion is performed using the relationship I=k*V+b, where k is the sampling ratio and b is the DC bias. The specific functional relationship between the protection threshold voltage and the power device temperature and bus voltage is as follows: .

[0011] In one possible implementation of the first aspect, in step S6, the operating temperature range of the power device is limited by the short-time overload temperature rise of the power device.

[0012] According to a second aspect of the present invention, a threshold-adaptive wave-by-wave current limiting protection circuit is provided, comprising: A controller used to generate square wave signals with adjustable duty cycles; A shaping circuit, connected to the output port of the controller, is used to shape the square wave signal and output a standard square wave signal. A low-pass filter circuit is connected to the output of the shaping circuit to filter the standard square wave signal and output a DC voltage as the protection threshold for wave-by-wave current limiting protection. The controller is further configured as follows: Monitor the temperature of power devices and the bus voltage of the system; Determine whether the output power of the system changes within a predetermined time period; If the output power does not change within a predetermined time, the protection threshold is calculated and updated based on the current temperature of the power device and the current value of the bus voltage. If the output power changes within a predetermined time period, the protection threshold is set to a preset minimum value. The updated protection threshold is achieved by adjusting the duty cycle of the square wave signal.

[0013] In one possible implementation of the second aspect, when calculating the protection threshold based on the current temperature of the power device and the current value of the bus voltage, the calculation is performed based on an adaptive function relationship, which is established in the following manner: First, with the power device temperature fixed, the power device current is constrained by the voltage stress specification of the power device to obtain the functional relationship between the power device current and the bus voltage that satisfies the stress. Then, the temperature of the power device is extended to the entire operating temperature range to obtain the objective function relationship; Finally, based on the sampling coefficient of the power device current by the controller, the objective function relationship is converted into a function relationship between the protection threshold voltage and the power device temperature and the bus voltage.

[0014] In one possible implementation of the second aspect, the objective function relationship is I=F(T, U, I), where I represents the power device current, T represents the power device temperature, and U represents the bus voltage; When converting the target function relationship into a function of the protection threshold voltage V, the conversion is performed using the relationship I=k*V+b, where k is the sampling ratio and b is the DC bias. The specific functional relationship between the protection threshold voltage and the power device temperature and bus voltage is as follows: .

[0015] Compared with the prior art, the present invention has at least the following beneficial effects: This invention overcomes the problem of non-protection or false protection under complex application scenarios and power grid characteristics caused by fixed thresholds by dynamically adjusting the wave-by-wave current limiting protection threshold. The protection threshold can adaptively change with operating conditions, ensuring accurate triggering of protection actions under various operating conditions and effectively preventing overcurrent damage to power devices. The protection threshold is automatically calculated and updated based on the real-time temperature of the power devices and the system bus voltage, adapting to aging phenomena and changes in operating conditions during long-term equipment operation. This ensures that the protection mechanism always matches the actual state of the equipment, improving the long-term reliability and stability of the system. When the system output power is stable, the protection threshold is optimized according to the current temperature and bus voltage, avoiding the wasted capacity caused by designing fixed thresholds based on the most severe thermal and stress conditions. This allows the potential of power devices and energy storage converters to be fully utilized, improving equipment operating efficiency and reducing economic costs. When the system output power changes within a predetermined time, the protection threshold automatically switches to a preset minimum value, ensuring rapid entry into protection mode under dynamic conditions. This prevents power devices from being damaged by overcurrent during sudden changes, enhancing the system's transient response capability and making it safer. The controller outputs an adjustable duty cycle square wave signal, which, combined with shaping and filtering circuits, generates a protection threshold. The hardware structure is simple, the software control is flexible and easy to implement, and it is easy to integrate into existing energy storage converter systems without complex modifications, thus reducing implementation and maintenance costs.

[0016] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the specific embodiments of the present invention, the drawings used in the description of the specific embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 It is a conventional wave-by-wave current limiting circuit.

[0019] Figure 2 These are the fixed protection thresholds V1 and V2 of the reference voltage divider.

[0020] Figure 3 This invention relates to an adjustable protection threshold voltage circuit for the controller output.

[0021] Figure 4 This is an adaptive method for protecting the threshold of the present invention.

[0022] Figure 5 This is a flowchart of a threshold-adaptive wave-by-wave current limiting protection method according to the present invention. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] This invention provides a threshold-adaptive wave-by-wave current limiting protection method, which can be implemented through a combination of hardware circuitry and software programming. In a typical implementation, a microcontroller (MCU) or digital signal processor (DSP) is used as the control unit, working in conjunction with peripheral circuitry to execute each step. Figure 5 As shown below, each step of the method is described in detail.

[0025] S1. A square wave signal is generated through the output port of the controller, and the duty cycle of the square wave signal is adjustable.

[0026] Specifically, one output port of the controller (such as an MCU or DSP) is configured to generate a square wave signal. This output port can be a general purpose input / output (GPIO) pin or a dedicated pulse width modulation (PWM) output pin. The controller adjusts the duty cycle of the square wave signal via an internal timer or PWM module. The frequency of the square wave signal is typically set to a fixed value. The duty cycle is adjusted by modifying register values ​​in the controller, thereby changing the proportion of high-level time in the output square wave signal.

[0027] S2. The square wave signal is input to the shaping circuit for shaping to obtain a standard square wave signal.

[0028] Specifically, the square wave signal output from the controller may contain noise or waveform distortion, so it needs to be shaped by a shaping circuit.

[0029] In one implementation, the shaping circuit can be implemented using a Schmitt trigger or an analog switching circuit. For example, a Schmitt trigger converts an input square wave signal into a standard square wave signal with standard high and low levels by setting an appropriate threshold voltage, eliminating signal jitter and overshoot. The shaped standard square wave signal has fast rising and falling edges.

[0030] S3. The standard square wave signal is input to a low-pass filter circuit for filtering to obtain a DC voltage, which is used as the protection threshold for wave-by-wave current limiting protection.

[0031] Specifically, the shaped standard square wave signal is input to a low-pass filter circuit, which converts the square wave signal into a smooth DC voltage.

[0032] In one feasible implementation, the low-pass filter circuit can employ a passive RC filter or an active filter, such as a Butterworth filter constructed from operational amplifiers. The filter's cutoff frequency is set much lower than the fundamental frequency of the square wave signal, for example, less than 1 / 10 of the square wave frequency, to effectively filter out high-frequency components and retain the DC component. The output DC voltage value is proportional to the duty cycle of the square wave signal, and this DC voltage serves as the protection threshold for wave-by-wave current limiting protection, directly compared with the reactor current sampling value.

[0033] S4. Monitor the temperature of power devices and the bus voltage of the system.

[0034] Specifically, the temperature of the power devices is monitored in real time by temperature sensors, such as thermistors or integrated circuit temperature sensors. These sensors are mounted near the power devices or on the heat sink and output analog voltage or digital signals. These signals are then processed by a signal conditioning circuit before being input to the controller's analog-to-digital converter (ADC) port. The system bus voltage is monitored by a voltage sampling circuit, which includes voltage divider resistors and an isolation operational amplifier, converting the high bus voltage to a voltage range acceptable to the controller's ADC.

[0035] S5. Determine whether the output power of the system changes within a predetermined time period.

[0036] The system's output power is calculated by monitoring the output voltage and current, or obtained directly using a power measurement circuit. The controller compares the current output power with historical values ​​at predetermined time intervals to determine if there has been a change. The judgment criterion is based on a preset threshold; for example, if the change in output power exceeds 5% of the rated power, it is considered a change in output power; otherwise, it is considered no change. The predetermined time is set according to the system's dynamic response characteristics and is implemented periodically through the controller's timer module.

[0037] In one possible implementation, the predetermined time is 2 to 4 minutes, preferably 3 minutes.

[0038] S6. If the output power does not change within a predetermined time, the protection threshold is calculated and updated based on the current temperature of the power device and the current value of the bus voltage.

[0039] If the output power remains unchanged within a predetermined time, the controller calculates and updates the protection threshold based on the currently acquired power device temperature and bus voltage values. The calculation is performed using a pre-stored formula in the controller. The updated protection threshold is achieved by adjusting the duty cycle of the square wave signal.

[0040] In one possible implementation, when calculating the protection threshold based on the current temperature of the power device and the current value of the bus voltage, the calculation is performed based on an adaptive function relationship, which is established in the following manner: First, with the power device temperature fixed, the power device current is constrained by the voltage stress specification of the power device to obtain the functional relationship between the power device current and the bus voltage that satisfies the stress.

[0041] Then, the power device temperature is extended to the entire operating temperature range to obtain the objective function relationship, which is I=F(T, U, I), where I represents the power device current, T represents the power device temperature, and U represents the bus voltage.

[0042] Finally, based on the sampling coefficient of the power device current by the controller, the objective function relationship is converted into a function relationship between the protection threshold voltage and the power device temperature and the bus voltage.

[0043] In this embodiment, when converting the target function relationship into a function of the protection threshold voltage V, the conversion is performed using the formula I=k*V+b, where k is the sampling ratio and b is the DC bias. The specific functional relationship between the protection threshold voltage and the power device temperature and bus voltage is as follows: .

[0044] The operating temperature range of power devices is limited by the short-time overload temperature rise of the power devices. The short-time overload is the loss and temperature rise generated by the current of the power devices within 20 switching cycles.

[0045] S7. If the output power changes within a predetermined time, the protection threshold is set to a preset minimum value.

[0046] Specifically, if the output power changes within a predetermined time period, the controller sets the protection threshold to a preset minimum value. This minimum value is stored in the controller's memory to ensure its availability during system startup or reset. It should be noted that the minimum value setting is based on the minimum safe operating conditions of the power devices, such as the most severe thermal or stress conditions. The controller achieves rapid switching of the protection threshold by adjusting the duty cycle of the square wave signal to the duty cycle corresponding to the minimum protection threshold.

[0047] Throughout the process, the wave-by-wave current limiting protection circuit uses the DC voltage obtained in step S3 as the protection threshold and compares it with the reactor current sampling value. When the current exceeds the protection threshold, the protection action is triggered, blocking the drive wave of the power device to prevent overcurrent damage.

[0048] Through the above implementation methods, the present invention achieves adaptive adjustment of the current limiting protection threshold for each wave, making the protection more flexible and accurate, and able to adapt to different application scenarios, grid characteristics, equipment aging and changes in operating conditions, thus avoiding the waste of power devices and energy storage converter capabilities.

[0049] The present invention provides a threshold-adaptive wave-by-wave current limiting protection circuit, which achieves dynamic adjustment of the protection threshold through the coordinated operation of hardware circuit and controller software. Figure 3 This is a block diagram of one embodiment of the protection circuit described in this invention. Figure 3 As shown, the threshold adaptive wave-by-wave current limiting protection circuit mainly includes a controller, a shaping circuit, and a low-pass filter circuit.

[0050] The controller is the core control unit of the circuit, and one of its output ports is configured to generate a square wave signal with an adjustable duty cycle. This port is typically a general purpose input / output (GPIO) pin or a dedicated pulse width modulation (PWM) output pin. The controller adjusts the duty cycle of the square wave signal through internal registers.

[0051] The input of the shaping circuit is connected to the output port of the controller. The shaping circuit is used to shape the square wave signal from the controller, eliminate noise and distortion in the signal, and output a standard square wave signal with standard high and low levels and steep edges.

[0052] In one embodiment, the shaping circuit is implemented using a Schmitt trigger.

[0053] In another embodiment, the shaping circuit is implemented using an analog switch. The controller's output signal is connected to the control terminal of the analog switch. When the signal is high, the analog switch is turned on, outputting a stable reference high level; when the signal is low, the analog switch is turned off, and the output terminal is grounded through a pull-down resistor, thereby outputting a standard square wave signal.

[0054] The input of the low-pass filter circuit is connected to the output of the shaping circuit. The low-pass filter circuit is used to smooth the standard square wave signal into a DC voltage. The amplitude of this DC voltage is proportional to the duty cycle of the square wave signal and serves as the protection threshold voltage for wave-by-wave current limiting protection.

[0055] In one specific embodiment, the low-pass filter circuit employs a first-order passive RC filter, including a series resistor and a capacitor to ground. The filter's cutoff frequency is set much lower than the fundamental frequency of the square wave signal; for example, when the square wave frequency is 100kHz, the cutoff frequency can be set below 1kHz to ensure effective filtering of AC components and output of a smooth DC voltage.

[0056] In another embodiment, the low-pass filter circuit U3 employs an active filter.

[0057] The controller is further configured as follows: Monitor the temperature of power devices and the bus voltage of the system; Determine whether the output power of the system changes within a predetermined time period; If the output power does not change within a predetermined time, the protection threshold is calculated and updated based on the current temperature of the power device and the current value of the bus voltage. If the output power changes within a predetermined time period, the protection threshold is set to a preset minimum value. The updated protection threshold is achieved by adjusting the duty cycle of the square wave signal.

[0058] The controller is also configured to execute the following monitoring and control algorithms: The controller monitors the temperature of the power devices via its analog-to-digital converter (ADC) port. The temperature sensor is mounted near the power devices or on the heat sink, and its output signal is conditioned before being sent to the controller's ADC port.

[0059] The controller also monitors the system bus voltage through another ADC port and converts the high voltage to a voltage range acceptable to the controller's ADC.

[0060] The controller has pre-stored judgment logic to determine whether the system's output power changes within a predetermined time, such as 2 to 4 minutes. The output power is calculated by monitoring the system's output voltage and output current. The judgment criterion is based on a preset power change threshold; for example, if the change in output power exceeds 5% of the rated power, it is determined that there has been a change.

[0061] If the controller determines that the output power has not changed within a predetermined time, it calculates a new protection threshold based on the currently collected power device temperature value and bus voltage value using a pre-stored calculation formula, and updates the protection threshold by adjusting the duty cycle of its output square wave signal.

[0062] If the controller determines that the output power changes within a predetermined time period, it adjusts the duty cycle of its output square wave signal to a preset minimum value, thereby setting the protection threshold to the minimum value. This minimum value is stored in the controller's non-volatile memory, ensuring basic protection is provided in the event of system malfunction.

[0063] The protection threshold voltage output by the protection circuit is sent to the wave-by-wave current limiting comparison circuit and compared with the reactor current sampling value, thereby realizing adaptive overcurrent protection.

[0064] Detailed explanation is as follows: like Figure 3 This invention relates to a threshold-adaptive wave-by-wave current limiting protection circuit. A reference square wave signal with a fixed frequency and a duty cycle of D is generated from the controller's general-purpose output port or pulse width modulation port. Because the controller's power supply voltage accuracy is relatively low and there is a certain delay in the rise and fall level transitions, the reference square wave signal is shaped into a standard square wave signal by a shaping circuit, and then filtered into a DC voltage by a low-pass filter. The shaping circuit includes a Schmitt trigger or an analog switch. This method, by adjusting the duty cycle D of the controller's square wave signal, can output a DC voltage of VREF*D threshold value for use in... Figure 1 The upper threshold voltage V1 and the lower threshold voltage V2 are specified in the table.

[0065] To increase the adaptability of the threshold, a correlation function between the power device temperature, bus voltage, and protection threshold is designed based on the thermal and voltage stresses of the power device. Since the parameters of interest are the power device temperature T, power device current I, and power device voltage, and in energy storage converter systems, the reactor current is typically measured to represent the power device current, and the bus voltage is measured to assess the power device's voltage withstand capability, single-pulse and double-pulse tests are performed on the power device under the premise of fixed power device drive parameters. The functional relationship between the power device temperature T, power device current I, and bus voltage U is described as I=F(T, U, I). The function design steps are as follows: First, fix the power device temperature T0, and constrain the power device current I by the power device voltage stress specification to obtain the functional relationship between I and U that satisfies the stress: I=G(T0, U, I).

[0066] Then the power device temperature is extended from T0 to (T min T max), thus obtaining the objective function I=F(T , U, I), T∈(T min T max ). Among them, T min Generally, a minimum ambient temperature is set for the product, T. max Due to the limitation of short-term overload temperature rise of power devices, the losses and temperature rise generated by the current I of the power devices within 20 switching cycles are generally considered.

[0067] Based on the sampling coefficients of the controller for the power device current, i.e., the sampling coefficients for the reactor current, the relationship between the protection threshold voltage V and the power device current I is obtained as: I = k * V + b, where k is the sampling ratio and b is the DC bias. Substituting these values, we obtain the protection threshold voltage V:

[0068] Figure 4 The flowchart for the threshold adaptive program is as follows: Determine if the output power has changed within 3 minutes. If there is no change, the power device temperature T can be considered basically stable. Therefore, read the current power device temperature T1 and the current bus voltage U1, and solve and update the protection threshold V1 according to the function. If the power has changed, the power device temperature T has changed, and the minimum protection threshold V1 within the entire range is used by default. min This avoids situations where the system cannot function properly under sudden power surges.

[0069] The threshold-adaptive wave-by-wave current limiting protection circuit proposed in this invention solves the flexibility problem of traditional fixed protection thresholds. The designed adaptive function can increase the adaptability of wave-by-wave current limiting protection and improve the short-time overcurrent capability of power devices and energy storage converters under non-severe operating conditions.

[0070] In the description of this invention, it should be understood that the terms "upper", "lower", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0071] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0072] In this invention, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0073] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0074] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0075] Finally, it should be noted that the above-described embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit them. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the scope of the technology disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the scope of protection of the present invention.

Claims

1. A threshold-adaptive wave-by-wave current limiting protection method, characterized in that, Includes the following steps: S1. A square wave signal is generated through the output port of the controller, and the duty cycle of the square wave signal is adjustable; S2. Input the square wave signal into the shaping circuit for shaping to obtain a standard square wave signal; S3. The standard square wave signal is input to a low-pass filter circuit for filtering to obtain a DC voltage, which is used as the protection threshold for wave-by-wave current limiting protection. S4. Monitor the temperature of power devices and the bus voltage of the system; S5. Determine whether the output power of the system changes within a predetermined time period; S6. If the output power does not change within a predetermined time, the protection threshold is calculated and updated based on the current temperature of the power device and the current value of the bus voltage. S7. If the output power changes within a predetermined time, the protection threshold is set to a preset minimum value. In step S6, the updated protection threshold is achieved by adjusting the duty cycle of the square wave signal.

2. The threshold-adaptive wave-by-wave current limiting protection method according to claim 1, characterized in that, The shaping circuit includes a Schmitt trigger or an analog switch.

3. The threshold-adaptive wave-by-wave current limiting protection method according to claim 1, characterized in that, The scheduled time is 2 to 4 minutes.

4. The threshold-adaptive wave-by-wave current limiting protection method according to claim 1, characterized in that, In step S6, when calculating the protection threshold based on the current temperature of the power device and the current value of the bus voltage, the calculation is performed based on an adaptive function relationship, which is established in the following way: First, with the power device temperature fixed, the power device current is constrained by the voltage stress specification of the power device to obtain the functional relationship between the power device current and the bus voltage that satisfies the stress. Then, the temperature of the power device is extended to the entire operating temperature range to obtain the objective function relationship; Finally, based on the sampling coefficient of the power device current by the controller, the objective function relationship is converted into a function relationship between the protection threshold voltage and the power device temperature and the bus voltage.

5. A threshold-adaptive wave-by-wave current limiting protection method according to claim 4, characterized in that, The objective function relationship is I=F(T, U, I), where I represents the power device current, T represents the power device temperature, and U represents the bus voltage.

6. The threshold-adaptive wave-by-wave current limiting protection method according to claim 5, characterized in that, When converting the target function relationship into a function of the protection threshold voltage V, the conversion is performed using the relationship I=k*V+b, where k is the sampling ratio and b is the DC bias. The specific functional relationship between the protection threshold voltage and the power device temperature and bus voltage is as follows: 。 7. The threshold-adaptive wave-by-wave current limiting protection method according to claim 1, characterized in that, In step S6, the operating temperature range of the power device is limited by the short-term overload temperature rise of the power device.

8. A threshold-adaptive wave-by-wave current limiting protection circuit, characterized in that, include: A controller used to generate square wave signals with adjustable duty cycles; A shaping circuit, connected to the output port of the controller, is used to shape the square wave signal and output a standard square wave signal. A low-pass filter circuit is connected to the output of the shaping circuit to filter the standard square wave signal and output a DC voltage as the protection threshold for wave-by-wave current limiting protection. The controller is further configured as follows: Monitor the temperature of power devices and the bus voltage of the system; Determine whether the output power of the system changes within a predetermined time period; If the output power does not change within a predetermined time, the protection threshold is calculated and updated based on the current temperature of the power device and the current value of the bus voltage. If the output power changes within a predetermined time period, the protection threshold is set to a preset minimum value. The updated protection threshold is achieved by adjusting the duty cycle of the square wave signal.

9. A threshold-adaptive wave-by-wave current limiting protection circuit according to claim 8, characterized in that, When calculating the protection threshold based on the current temperature of the power device and the current value of the bus voltage, the calculation is based on an adaptive function relationship, which is established in the following way: First, with the power device temperature fixed, the power device current is constrained by the voltage stress specification of the power device to obtain the functional relationship between the power device current and the bus voltage that satisfies the stress. Then, the temperature of the power device is extended to the entire operating temperature range to obtain the objective function relationship; Finally, based on the sampling coefficient of the power device current by the controller, the objective function relationship is converted into a function relationship between the protection threshold voltage and the power device temperature and the bus voltage.

10. A threshold-adaptive wave-by-wave current limiting protection circuit according to claim 9, characterized in that, The objective function relationship is I=F(T, U, I), where I represents the power device current, T represents the power device temperature, and U represents the bus voltage. When converting the target function relationship into a function of the protection threshold voltage V, the conversion is performed using the relationship I=k*V+b, where k is the sampling ratio and b is the DC bias. The specific functional relationship between the protection threshold voltage and the power device temperature and bus voltage is as follows: 。

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