Inverter circuit output short circuit detection method, inverter circuit and ard rescue power supply

Abstract

The application relates to an inverter circuit output short circuit detection method, an inverter circuit and an ARD rescue power supply. The method comprises the following steps: controlling an inverter circuit to output a high-frequency voltage signal to a load of the inverter circuit; detecting a load voltage of the inverter circuit and taking the load voltage as a feedback voltage output by the inverter circuit; performing multi-cycle effective value detection on the feedback voltage, determining a short circuit abnormality number of the feedback voltage within a preset detection time, and judging whether the inverter circuit output is short circuited according to the short circuit abnormality number. The method can quickly identify the output short circuit without additional circuits, and has the technical characteristics of low cost, high reliability, good accuracy and high efficiency.

Description

Technical Field

[0001] This application relates to the field of short-circuit protection technology, and in particular to a method for detecting short circuits in inverter circuit outputs, an inverter circuit, and an ARD rescue power supply. Background Technology

[0002] An inverter circuit is a conversion device that converts direct current (DC) to alternating current (AC). It is widely used in power supplies, frequency converters, and drives of various electrical equipment. For example, in the elevator industry, every elevator is required to be equipped with an ARD (Automatic Rescuer Device) power supply. Its main function is to convert the DC power from the battery to AC power to provide temporary power in the event of a sudden power outage during elevator operation. This provides temporary power to the elevator drive, door operator, car lighting, and internal / external call displays, thus preventing passengers from being trapped in the elevator.

[0003] During the installation and use of inverter circuits, short circuits at the output terminals may occur due to incorrect wiring sequence. The traditional method for detecting output short circuits is usually current identification, which involves adding a current detection circuit to the hardware circuit. When a short circuit occurs at the downstream end, a large current will be generated instantaneously, and the judgment is made by detecting the magnitude of the current. This method not only increases the circuit cost but also has a certain response time. In particular, if there is a large inductance in the inverter circuit, the presence of voltage in the circuit will affect the accuracy of the judgment, and the continuous presence of a large current may also damage the power devices. Summary of the Invention

[0004] Therefore, it is necessary to provide an inverter circuit output short circuit detection method, inverter circuit, and ARD rescue power supply that can quickly identify output short circuits without additional circuitry, addressing the aforementioned technical problems.

[0005] In a first aspect, this application provides a method for detecting short circuits at the output of an inverter circuit, the method comprising:

[0006] Control the inverter circuit to output a high-frequency voltage signal, which is then output to the load of the inverter circuit;

[0007] The load voltage of the inverter circuit is detected, and the load voltage is used as the feedback voltage of the inverter circuit output.

[0008] The effective value of the feedback voltage is detected over multiple cycles to determine the number of short-circuit anomalies in the feedback voltage within a preset detection time, and the output of the inverter circuit is determined to be short-circuited based on the number of short-circuit anomalies.

[0009] In one embodiment, the inverter circuit includes an inverter bridge, and controlling the inverter circuit to output a high-frequency voltage signal includes:

[0010] The switching transistors in the inverter bridge are controlled by PWM modulation to modulate the output high-frequency voltage signal.

[0011] In one embodiment, controlling the inverter circuit to output a high-frequency voltage signal includes:

[0012] Before the overcurrent protection of the inverter circuit is triggered, the inverter circuit is controlled to output a high-frequency voltage signal within a preset detection time, wherein the preset detection time is shorter than the trigger time of the overcurrent protection.

[0013] In one embodiment, detecting the load voltage of the inverter circuit and using the load voltage as the feedback voltage output by the inverter circuit includes:

[0014] The load voltage of the inverter circuit is detected by the original voltage sampling circuit in the inverter circuit, and the load voltage is used as the feedback voltage. The original voltage sampling circuit is used to detect the load voltage of the inverter circuit and provide feedback when the inverter circuit is operating normally.

[0015] In one embodiment, the feedback voltage is subjected to multi-cycle effective value detection to determine the number of short-circuit anomalies in the feedback voltage within a preset detection time, including:

[0016] Within a preset detection time, the feedback voltage of multiple cycles is compared with the preset short-circuit voltage. If the feedback voltage of one cycle is less than the preset short-circuit voltage, the number of short-circuit anomalies is incremented by one. Otherwise, the number of short-circuit anomalies is not incremented until the preset detection time ends, and the number of short-circuit anomalies is obtained.

[0017] In one embodiment, determining whether the inverter circuit output is short-circuited based on the number of short-circuit anomalies includes:

[0018] If the number of short-circuit anomalies is greater than or equal to the preset number within the preset detection time, the inverter circuit output will be short-circuited, the inverter circuit will be shut down and a short-circuit fault warning will be issued; otherwise, the inverter circuit output will be normal and the inverter circuit will output at its normal rated value.

[0019] In one embodiment, the frequency of the high-frequency voltage signal is greater than the rated output voltage frequency of the inverter circuit, and the effective voltage value of the high-frequency voltage signal is less than the effective voltage value of the rated output voltage of the inverter circuit.

[0020] In one embodiment, the frequency of the high-frequency voltage signal is 6 to 12 times the frequency of the rated output voltage, and the effective value of the high-frequency voltage signal is 1 / 5 to 1 / 8 of the effective value of the rated output voltage.

[0021] Secondly, this application provides an inverter circuit, including at least a controller, an inverter bridge, a filter circuit, and a voltage sampling circuit. The controller is electrically connected to the control terminal of the inverter bridge, and the output terminal of the inverter bridge is electrically connected to an external load via the filter circuit. Under normal output conditions of the inverter circuit, the voltage sampling circuit is used to detect the load voltage and feed the load voltage back to the controller as the feedback voltage of the inverter circuit output. The controller is used to stabilize the output voltage of the inverter bridge based on the feedback voltage.

[0022] In the short-circuit detection state of the inverter circuit output, the controller is also used to control the inverter bridge to output a high-frequency voltage signal to the external load, and to perform multi-cycle effective value detection on the obtained feedback voltage to determine the number of short-circuit anomalies in the feedback voltage within the preset detection time, and to determine whether the output of the inverter circuit is short-circuited based on the number of short-circuit anomalies.

[0023] Thirdly, this application provides an ARD rescue power supply, which includes at least the inverter circuit described in any of the above embodiments.

[0024] The aforementioned inverter circuit output short-circuit detection method, inverter circuit, and ARD rescue power supply utilize the existing inverter circuit to generate a high-frequency voltage signal, which is injected into its load. Output short-circuit detection is then performed based on the feedback voltage output by the inverter circuit. Specifically, the feedback voltage undergoes multi-cycle effective value detection to determine the number of short-circuit anomalies within a preset detection time, thereby determining whether the inverter output is short-circuited. Firstly, this eliminates the need for any additional circuitry; output short-circuit detection can be achieved using the existing inverter circuit. Specifically, the voltage sampling circuit in the existing inverter circuit collects the load voltage at the time of the high-frequency voltage signal output and uses it as the feedback voltage to detect output short circuits. This method is low-cost, simple, and efficient. Secondly, the use of a high-frequency voltage signal for detection improves the response speed of short-circuit detection, and the accumulated number of short-circuit anomalies in the feedback voltage enhances the accuracy of output short-circuit detection. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the overall process of an inverter circuit output short-circuit detection method in one embodiment;

[0027] Figure 2 This is a flowchart illustrating the workflow of an inverter circuit output short-circuit detection method in one embodiment.

[0028] Figure 3 This is a schematic diagram of the voltage output frequency switching waveform of an inverter circuit output short-circuit detection method in one embodiment.

[0029] Figure 4 This is a schematic diagram of the output voltage waveform during a short circuit in an embodiment of the inverter circuit output short circuit detection method.

[0030] Figure 5 This is a hardware control block diagram of the inverter circuit in one embodiment.

[0031] Explanation of reference numerals in the attached figures:

[0032] 10. Controller; 20. Inverter bridge; 30. Filter circuit; 40. Voltage sampling circuit. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0035] It should be noted that when one element is considered to be "connected" to another element, it can be directly connected to the other element or connected to the other element through an intermediary element. Furthermore, in the following embodiments, "connection" should be understood as "electrical connection," "communication connection," etc., if there is transmission of electrical signals or data between the connected objects.

[0036] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising,” “including,” or “having,” etc., specify the presence of the stated feature, whole, step, operation, component, part, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof.

[0037] The inverter circuit output short-circuit detection method provided in this application embodiment can be applied to the inverter circuits of devices such as power supplies, frequency converters, and drivers to realize output short-circuit detection. Furthermore, it is particularly suitable for the inverter circuit of elevator ARD rescue power supply, so that output short-circuit detection can be performed through the original inverter circuit without additional circuit.

[0038] In one embodiment, such as Figure 1 As shown, a method for detecting short circuits at the output of an inverter circuit is provided. The method includes:

[0039] S100: Controls the inverter circuit to output a high-frequency voltage signal, which is then output to the load of the inverter circuit;

[0040] Among them, the high-frequency voltage signal is different from the normal output signal of the inverter circuit. For example, the frequency of the electrical signal output by a conventional inverter circuit is generally 50Hz or 60Hz and the effective voltage value is 220V. The corresponding high-frequency voltage signal will use an electrical signal with a higher frequency and a lower effective voltage value, such as 500Hz and 30V. The frequency and voltage value of the high-frequency voltage signal are selected according to the inverter circuit structure and circuit output characteristics.

[0041] Specifically, the high-frequency voltage signal is modulated and output through the existing inverter circuit. The controller in the inverter circuit controls the switching of the transistors in the upper and lower arms of the inverter bridge, thereby modulating the high-frequency voltage signal and outputting it to the load of the inverter circuit for short-circuit detection. Using the high-frequency voltage signal instead of the original normal output signal for short-circuit detection not only results in a faster response time and avoids generating large currents, but also provides lower voltage, thus effectively protecting the circuit components.

[0042] S200: Detects the load voltage of the inverter circuit and uses the load voltage as the feedback voltage of the inverter circuit output.

[0043] Specifically, the load voltage of the inverter circuit is detected by the original voltage sampling circuit of the inverter circuit. In the normal operation state of the inverter circuit, the voltage sampling circuit is used to detect the load voltage when the voltage output is normal and use it as feedback voltage. The controller stabilizes the voltage output of the inverter circuit through this feedback. In the output short circuit detection state, the original voltage sampling circuit is used to detect the load voltage when the high-frequency voltage signal is output and use it as feedback voltage. The controller further performs short circuit detection judgment through this feedback, realizing a new application of the voltage sampling circuit in the inverter circuit for output short circuit detection.

[0044] S300: Performs multi-cycle effective value detection on the feedback voltage, determines the number of short-circuit anomalies in the feedback voltage within a preset detection time, and judges whether the inverter circuit output is short-circuited based on the number of short-circuit anomalies.

[0045] Specifically, the short circuit of the inverter circuit output is detected by the feedback voltage of the inverter circuit output. When a short circuit exists in the load, the feedback voltage should be at its minimum value. Based on this, it can be determined whether there is a short circuit anomaly in the feedback voltage. However, due to the presence of inductance in the inverter circuit, the diversity and uncertainty of the inverter circuit load, and the existence of dead zone effect, the output voltage will be distorted compared with the ideal sine wave, that is, the effective value of the feedback voltage will deviate. Therefore, this embodiment uses the effective value of the feedback voltage in multiple cycles to detect whether the inverter circuit output is short-circuited, so as to improve the reliability and accuracy of the detection. Specifically, the number of short circuit anomalies in the feedback voltage is determined by the effective value of the feedback voltage in multiple cycles. That is, if there is a short circuit anomaly in the effective value of the feedback voltage in one cycle, it is counted as one short circuit anomaly. Thus, the short circuit anomaly is determined by the number of short circuit anomalies in the preset detection time.

[0046] It is worth noting that in this embodiment, the structure of all inverter circuits, including the voltage sampling circuit, remains unchanged. In both normal operation and short-circuit detection states, the inverter circuit outputs a voltage signal. In normal operation, a normal voltage signal is output; in short-circuit detection state, a high-frequency voltage signal is output. Both outputs are fed back by the voltage sampling circuit detecting the load voltage of the inverter circuit. The only difference is that in normal operation, the controller in the inverter circuit directly adjusts the output voltage of the inverter bridge via a PI controller based on the feedback voltage. In short-circuit detection state, the controller in the inverter circuit performs multi-cycle effective value detection based on the feedback voltage to determine the number of short-circuit anomalies in the feedback voltage within a preset detection time, and then determines whether the inverter circuit output is short-circuited based on the number of short-circuit anomalies.

[0047] The aforementioned inverter circuit output short-circuit detection method injects a high-frequency voltage signal generated by the existing inverter circuit into its load and performs output short-circuit detection based on the feedback voltage output by the inverter circuit. Specifically, the effective value of the feedback voltage is detected over multiple cycles to determine the number of short-circuit anomalies within a preset detection time, thereby determining whether the inverter output is short-circuited. Firstly, this method eliminates the need for any additional circuitry; the existing inverter circuit can perform output short-circuit detection. Specifically, the voltage sampling circuit in the existing inverter circuit collects the load voltage at the time of the high-frequency voltage signal output and uses it as the feedback voltage to detect whether the output is short-circuited. This method is low-cost, simple, and efficient. Secondly, the use of a high-frequency voltage signal for detection improves the response speed of short-circuit detection, and the cumulative number of short-circuit anomalies in the feedback voltage improves the accuracy of output short-circuit detection.

[0048] In one embodiment, the inverter circuit includes an inverter bridge, and controlling the output high-frequency voltage signal of the inverter circuit includes: controlling the switching transistors in the inverter bridge through PWM modulation to modulate the output high-frequency voltage signal.

[0049] Specifically, this embodiment uses a PWM controller based on PWM modulation to control the switching transistors of the upper and lower bridge arms in the inverter bridge of the inverter circuit, adjusting the duty cycle and the number of pulses per unit time to control the voltage and frequency of the high-frequency voltage signal output by the inverter bridge. The duty cycle refers to the proportion of the on-time relative to the total time within one pulse cycle. Controlling the switching duration of the upper and lower bridge arms in the inverter circuit within a unit time can adjust the duty cycle of the high-frequency voltage signal. For example, if a 5V voltage signal is on for 0.5s within 1s, the duty cycle is 50%, and the corresponding effective voltage value is 2.5V. This achieves voltage value adjustment of the high-frequency voltage signal. The number of pulses per unit time, controlled by the switching frequency of the upper and lower bridge arms in the inverter circuit, can adjust the frequency of the high-frequency voltage signal. For example, if a 5V voltage signal changes from high to low and back to high 50 times within 1s, the corresponding signal frequency is 50Hz. Combining these two aspects of modulation yields the desired high-frequency voltage signal.

[0050] In one embodiment, to protect the circuit, the effective value of the high-frequency voltage signal is less than the effective value of the rated output voltage of the inverter circuit, so as to reduce the instantaneous current through the power devices of the inverter circuit and thus avoid damage to the devices during short circuit. Specifically, the effective value of the high-frequency voltage signal is set according to the selection of different power devices, loads, and circuit inductors of the inverter circuit.

[0051] Furthermore, the effective value of the high-frequency voltage signal can be 1 / 5 to 1 / 8 of the effective value of the rated output voltage. In this way, while reducing the damage of short circuits to circuit devices, the short circuit detection is ensured to have a certain sensitivity, and the short circuit abnormality of the feedback voltage can be accurately judged.

[0052] In one embodiment, controlling the output of a high-frequency voltage signal from the inverter circuit includes: controlling the output of the high-frequency voltage signal from the inverter circuit within a preset detection time before the overcurrent protection of the inverter circuit is triggered, wherein the preset detection time is less than the trigger time of the overcurrent protection.

[0053] Specifically, in order to improve the response speed and avoid conflict with the original overcurrent protection of the inverter circuit, this embodiment presets the detection time to be shorter than the trigger time of the overcurrent protection. This preset detection time is the output time of the high-frequency voltage signal. The output time of the high-frequency voltage signal is controlled so that the detection of the short circuit at the output of the inverter circuit is completed before the overcurrent protection is triggered. Specifically, the output time of the high-frequency voltage signal is set according to the different power devices, loads, and circuit inductors of the inverter circuit.

[0054] For example, if the overcurrent protection trigger time of the inverter circuit is 70ms, and a short circuit occurs, the instantaneous current through the power device can reach approximately 60A. Therefore, short-circuit protection needs to be initiated when the current is relatively low; that is, the corresponding short-circuit detection must be completed before this time to avoid generating a large current. Similarly, in the above scenario, if the inverter circuit output time is within 20ms, the current through the power device in the event of a short circuit will be less than 10A, which is within the normal operating current range. This allows us to determine the output time of the high-frequency voltage signal, i.e., the preset detection time. In other words, completing the short-circuit detection of the inverter circuit output within 20ms can prevent the generation of a large current and avoid conflict with the inverter circuit's original overcurrent protection.

[0055] In one embodiment, based on the aforementioned preset detection time requirement, in order to meet the short-circuit detection requirement for multiple cycles within the preset detection time, it is necessary to further improve the response speed, i.e., increase the frequency of the high-frequency voltage signal. In this embodiment, the frequency of the high-frequency voltage signal is greater than the rated output voltage frequency of the inverter circuit. As in the example above, the rated output voltage frequency is generally 50Hz or 60Hz. This is far from sufficient for the response time of multi-cycle short-circuit detection for a single voltage cycle. Therefore, the frequency of the final high-frequency voltage signal is determined according to the number of required detection cycles. For example, if at least 10 cycles are required, the frequency of the high-frequency voltage signal can be set to at least 500Hz, i.e., 2ms per cycle, to achieve a fast response and meet the response time requirement.

[0056] Furthermore, the frequency of the high-frequency voltage signal is 6 to 12 times the frequency of the rated output voltage. In this way, the short-circuit detection of the inverter output is completed before the overcurrent protection of the inverter circuit is triggered, while avoiding excessively high frequencies that cause the inverter circuit to produce varying degrees of howling noise.

[0057] In one embodiment, performing multi-cycle effective value detection on the feedback voltage and determining the number of short-circuit anomalies of the feedback voltage within a preset detection time includes: comparing the magnitude of the feedback voltage of multiple cycles with the preset short-circuit voltage within the preset detection time; if the feedback voltage of one cycle is less than the preset short-circuit voltage, the number of short-circuit anomalies is incremented by one; otherwise, the number of short-circuit anomalies is not incremented until the preset detection time ends, thus obtaining the number of short-circuit anomalies.

[0058] Specifically, this embodiment uses a preset short-circuit voltage to determine the short circuit of the feedback voltage in each cycle. Under normal conditions, the feedback voltage under light load is greater than that under heavy load. Under load short-circuit conditions, the feedback voltage should be at its minimum. Therefore, the preset short-circuit voltage is set according to the maximum load of the inverter circuit to simultaneously meet the short-circuit detection requirements of different load conditions and avoid misjudgments. Furthermore, due to the presence of filter inductors and dead-time effects in the inverter circuit, the preset short-circuit voltage needs to be further specifically set and adjusted to meet the specific conditions of the current inverter circuit, thereby improving the accuracy of short-circuit detection.

[0059] Specifically, to further improve the accuracy and reliability of short-circuit detection at the inverter circuit output, this embodiment performs multi-cycle detection of the feedback voltage within a preset detection time. In each cycle, the effective value of the feedback voltage is calculated and compared with a preset short-circuit voltage to determine whether a short-circuit anomaly exists in the circuit output during that cycle. The number of short-circuit anomaly cycles within the preset detection time is counted to determine the inverter circuit output status within the preset detection time.

[0060] If the number of short-circuit anomalies is greater than or equal to the preset number, it indicates that there is a short circuit in the inverter circuit output within the preset detection time. In this case, the controller of the inverter circuit needs to be turned off to stop the output of the inverter circuit and issue a short-circuit fault warning. If the number of short-circuit anomalies is less than the preset number, it indicates that there is no short circuit in the inverter circuit output within the preset detection time. In this case, the inverter circuit can output the rated voltage normally.

[0061] Compared to the traditional method of short-circuit detection based on instantaneous voltage values, the multi-cycle effective value detection method in this embodiment is less susceptible to deviation interference, has higher reliability, and provides higher accuracy by combining the results of multiple cycles. Furthermore, it eliminates the need for the sampling circuit added in traditional circuits, resulting in zero hardware cost and high efficiency.

[0062] It should be noted that the inverter circuit output short-circuit detection method in this embodiment is used to perform output short-circuit detection before the inverter circuit outputs normally, so as to determine whether the inverter circuit is normal before outputting. That is, the inverter circuit output short-circuit detection method of this embodiment is performed before the inverter circuit starts to output to the load in normal PI closed-loop regulation. If there is no short-circuit abnormality, it automatically switches back to the normal frequency and voltage signal output.

[0063] This embodiment will now be described in detail with reference to a specific application scenario, but it is not limited thereto.

[0064] In elevator ARD emergency power supply applications, short circuit detection is performed using the aforementioned inverter circuit output short circuit detection method:

[0065] See Figure 2When the power supply is performing inverter output, it first outputs a high-frequency voltage signal with a preset detection time of 20ms via PWM modulation of the original inverter circuit. The frequency of this high-frequency voltage signal is 500Hz, and the voltage setting is 30V. Within the preset detection time, the voltage sampling circuit in the original inverter circuit detects the feedback voltage output by the power supply, and the controller calculates the effective value of the feedback voltage for each cycle. When the effective value of the feedback voltage corresponding to one cycle is less than the preset short-circuit voltage of 10V, a short-circuit fault is counted. If the short-circuit fault count accumulates to 10 within 20ms, see [link to relevant documentation]. Figure 4 If the inverter circuit output is short-circuited, the PWM output of the inverter circuit will be shut down and a fault report will be issued. If the number of short-circuit anomalies is less than 10 within 20ms, refer to [the relevant documentation]. Figure 3 Then the power supply's inverter circuit switches to the normal 50Hz voltage frequency and closes the loop PI regulation output. At this time, the feedback voltage conversion of the voltage sampling circuit is used to stabilize the power supply output.

[0066] The inverter circuit output short-circuit detection method in this embodiment has the advantages of simple and effective implementation, high stability, low cost, and timely response. This method eliminates the need for traditional hardware sampling circuits to detect short-circuit faults. By using feedback from high-frequency voltage signals, it quickly identifies whether there is a short circuit at the output terminal. When the output terminal is determined to be normal, it promptly switches the frequency to the normal electrical frequency and performs closed-loop PI regulation on the output voltage. For ARD rescue power supply applications, it not only has a fast response speed and does not affect its normal use, but also provides reliable short-circuit protection.

[0067] It should be understood that although the steps in the flowcharts of the above embodiments are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the above embodiments may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0068] Based on the same inventive concept, this application also provides an inverter circuit for implementing the inverter circuit output short-circuit detection method described above. The solution provided by this device is similar to the implementation described in the above method; therefore, the specific limitations in one or more inverter circuit embodiments provided below can be found in the limitations of the inverter circuit output short-circuit detection method described above, and will not be repeated here.

[0069] In one embodiment, such as Figure 5 As shown, an inverter circuit is provided, which includes at least a controller 10, an inverter bridge 20, a filter circuit 30, and a voltage sampling circuit 40. The controller 10 is electrically connected to the control terminal of the inverter bridge 20, and the output terminal of the inverter bridge 20 is electrically connected to an external load via the filter circuit 30.

[0070] In the normal output state of the inverter circuit, the voltage sampling circuit 40 is used to detect the load voltage and feed the load voltage as the feedback voltage of the inverter circuit output to the controller 10. The controller 10 is used to stabilize the output voltage of the inverter bridge 20 based on the output voltage feedback of the voltage sampling circuit 40.

[0071] In the short-circuit detection state of the inverter circuit output, the controller 10 is also used to control the inverter bridge 20 to output a high-frequency voltage signal to the load of the inverter circuit. The voltage sampling circuit 40 is also used to detect the load voltage and feed the load voltage as the feedback voltage of the inverter circuit output back to the controller 10. The controller 10 is also used to perform multi-cycle validity detection on the feedback voltage, determine the number of short-circuit anomalies of the feedback voltage within a preset detection time, and determine whether the output of the inverter circuit is short-circuited based on the number of short-circuit anomalies.

[0072] In one embodiment, the controller controls the inverter circuit to output a high-frequency voltage signal by: controlling the switching transistors in the inverter bridge through PWM modulation to modulate the output high-frequency voltage signal.

[0073] In one embodiment, the controller controls the inverter circuit to output a high-frequency voltage signal by: controlling the high-frequency voltage signal output by the inverter circuit within a preset detection time before the overcurrent protection of the inverter circuit is triggered, wherein the preset detection time is less than the trigger time of the overcurrent protection.

[0074] In one embodiment, the voltage sampling circuit detects the load voltage of the inverter circuit and uses the load voltage as the feedback voltage output by the inverter circuit. This includes: detecting the load voltage of the inverter circuit using the existing voltage sampling circuit in the inverter circuit, and using the load voltage as the feedback voltage. The existing voltage sampling circuit is used to detect and feed back the load voltage of the inverter circuit under normal operating conditions. Specifically, the voltage sampling circuit can be implemented using conventional voltage sampling circuit structures such as amplifiers.

[0075] In one embodiment, the controller performs multi-cycle effective value detection on the feedback voltage to determine the number of short-circuit anomalies within a preset detection time. This includes comparing the feedback voltage over multiple cycles with a preset short-circuit voltage within the preset detection time. If the feedback voltage in one cycle is less than the preset short-circuit voltage, the short-circuit anomaly count is incremented by one; otherwise, the count is not incremented until the preset detection time ends, thus obtaining the total number of short-circuit anomalies. Specifically, the controller includes a CPU to implement the above functions.

[0076] In one embodiment, the controller determines whether the inverter circuit output is short-circuited based on the number of short-circuit anomalies. This includes: if the number of short-circuit anomalies is greater than or equal to the preset number within a preset detection time, the inverter circuit output is short-circuited, the inverter circuit is shut down, and a short-circuit fault warning is issued; otherwise, the inverter circuit output is normal, and the inverter circuit outputs normally at its rated value.

[0077] In one embodiment, the frequency of the high-frequency voltage signal is greater than the rated output voltage frequency of the inverter circuit, and the effective voltage value of the high-frequency voltage signal is less than the effective voltage value of the rated output voltage of the inverter circuit.

[0078] In one embodiment, the frequency of the high-frequency voltage signal is 6 to 12 times the frequency of the rated output voltage, and the effective value of the high-frequency voltage signal is 1 / 5 to 1 / 8 of the effective value of the rated output voltage.

[0079] The aforementioned inverter circuit generates a high-frequency voltage signal from the existing inverter circuit and injects it into its load. It then performs output short-circuit detection based on the feedback voltage output from the inverter circuit. Specifically, it performs multi-cycle effective value detection on the feedback voltage to determine the number of short-circuit anomalies within a preset detection time, thereby determining whether the inverter output is short-circuited. Firstly, without adding any related circuitry, the existing inverter circuit can complete the output short-circuit detection. Specifically, the voltage sampling circuit in the existing inverter circuit collects the load voltage at the time of the high-frequency voltage signal output and uses it as the feedback voltage to detect whether the output is short-circuited. This method is low-cost, simple, and efficient. Secondly, using a high-frequency voltage signal for detection improves the response speed of short-circuit detection, and accumulating the number of short-circuit anomalies in the feedback voltage improves the accuracy of output short-circuit detection.

[0080] In one embodiment, an ARD rescue power supply is also provided, comprising at least the inverter circuit described in any of the above embodiments. The ARD rescue power supply generally includes a battery, a DC / DC boost circuit, and a DC / AC inverter circuit connected in sequence, with the DC / AC inverter circuit connected to the load. When the ARD outputs, a DC / DC boost stage is first performed. When the controller determines that the feedback voltage has risen to the rated voltage, inversion (DC / AC) is performed. At this time, a high-frequency voltage signal is output by controlling the PWM duty cycle to enter the short-circuit detection state. For detailed explanations, please refer to the description corresponding to the output short-circuit detection method above, which will not be repeated here.

[0081] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0082] The above embodiments are merely illustrative of several implementation methods of this application, and their descriptions are relatively specific and detailed. However, they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A method for detecting short circuits at the output of an inverter circuit, characterized in that, The method includes: The inverter circuit is controlled to output a high-frequency voltage signal to the load of the inverter circuit within a preset detection time; wherein the preset detection time is less than the overcurrent protection trigger time of the inverter circuit. The load voltage of the inverter circuit is detected, and the load voltage is used as the feedback voltage output by the inverter circuit. The feedback voltage is subjected to multi-cycle effective value detection to determine the number of short-circuit anomalies of the feedback voltage within a preset detection time, and the output of the inverter circuit is short-circuited based on the number of short-circuit anomalies.

2. The method according to claim 1, characterized in that, The inverter circuit includes an inverter bridge, and the control inverter circuit outputs a high-frequency voltage signal including: The high-frequency voltage signal is modulated and output by controlling the switching transistors in the inverter bridge through PWM modulation.

3. The method according to claim 1, characterized in that, The step of detecting the load voltage of the inverter circuit and using the load voltage as the feedback voltage output by the inverter circuit includes: The load voltage of the inverter circuit is detected by the original voltage sampling circuit in the inverter circuit, and the load voltage is used as the feedback voltage. The original voltage sampling circuit is used to detect the load voltage of the inverter circuit and provide feedback when the inverter circuit is operating normally.

4. The method according to any one of claims 1 to 3, characterized in that, The step of performing multi-cycle effective value detection on the feedback voltage to determine the number of short-circuit anomalies in the feedback voltage within a preset detection time includes: Within the preset detection time, the magnitudes of the feedback voltage and the preset short-circuit voltage are compared over multiple cycles: if the feedback voltage of one cycle is less than the preset short-circuit voltage, the number of short-circuit anomalies is incremented by one; otherwise, the number of short-circuit anomalies is not incremented until the preset detection time ends, thus obtaining the number of short-circuit anomalies.

5. The method according to claim 4, characterized in that, The step of determining whether the output of the inverter circuit is short-circuited based on the number of short-circuit anomalies includes: If the number of short-circuit anomalies is greater than or equal to the preset number within the preset detection time, the inverter circuit output is short-circuited, the inverter circuit is shut down and a short-circuit fault warning is issued; otherwise, the inverter circuit output is normal and the inverter circuit outputs at its normal rated value.

6. The method according to any one of claims 1 to 3, characterized in that, The frequency of the high-frequency voltage signal is greater than the rated output voltage frequency of the inverter circuit, and the effective voltage value of the high-frequency voltage signal is less than the effective voltage value of the rated output voltage of the inverter circuit.

7. The method according to claim 6, characterized in that, The frequency of the high-frequency voltage signal is 6 to 12 times the frequency of the rated output voltage, and the effective value of the high-frequency voltage signal is 1 / 5 to 1 / 8 of the effective value of the rated output voltage.

8. An inverter circuit, comprising at least a controller, an inverter bridge, a filter circuit, and a voltage sampling circuit, wherein the controller is electrically connected to the control terminal of the inverter bridge, and the output terminal of the inverter bridge is electrically connected to an external load via the filter circuit; in the normal output state of the inverter circuit, the voltage sampling circuit is used to detect the load voltage and feed the load voltage as a feedback voltage of the inverter circuit output back to the controller; the controller is used to stabilize the output voltage of the inverter bridge according to the feedback voltage, characterized in that: In the short-circuit detection state of the inverter circuit output, the controller is also used to control the inverter bridge to output a high-frequency voltage signal to an external load within a preset detection time, and to perform multi-cycle effective value detection on the obtained feedback voltage to determine the number of short-circuit anomalies of the feedback voltage within the preset detection time, and to determine whether the output of the inverter circuit is short-circuited based on the number of short-circuit anomalies; wherein, the preset detection time is less than the overcurrent protection trigger time of the inverter circuit.

9. An ARD rescue power supply, characterized in that, It includes at least the inverter circuit as described in claim 8.

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