Overvoltage and undervoltage protection circuit for bus capacitor of inverter

Abstract

The utility model provides an inverter bus capacitor overvoltage and undervoltage protection circuit, and relates to the technical field of electronic circuits, a bus voltage sampling module of the technical scheme of the utility model obtains a sampling signal of bus voltage, and provides an accurate data basis for subsequent analysis. And then, the bus voltage analysis module judges the sampling signal, and compares a sampling voltage value with a preset voltage range, so that a voltage abnormal condition can be accurately identified. When a sampling voltage value exceeds a preset range, the bus voltage analysis module outputs a low-level signal, and the design enables the system to quickly respond to voltage fluctuation. And finally, when the bus overvoltage and undervoltage protection execution module receives the low-level signal, a protection measure is taken immediately, the inverter is controlled to stop working, and an alarm signal is output. The three-module linkage design improves the accuracy of voltage detection, gives consideration to the overvoltage and undervoltage conditions, and comprehensively improves the safety and reliability of the inverter.

Description

Technical Field

[0001] The present application relates to the technical field of electronic circuits, and in particular to an inverter bus capacitor overvoltage and undervoltage protection circuit. Background Art

[0002] With the rapid development of new energy technologies, the application scope of inverters in the market continues to expand, and their application scenarios are becoming increasingly diverse. This trend has led to more stringent requirements for inverter performance. Within the inverter's internal structure, the bus voltage detection circuit plays an indispensable role, directly affecting the safety and reliability of the equipment. Especially under loaded or no-load conditions, if the bus voltage is too low, the pure sine wave generated by the subsequent inverter stage may experience clipping and distortion. This can have serious consequences for precision electronic equipment that requires a stable and uniform energy supply.

[0003] Related technologies use voltage sampling and signal analysis to prevent busbar overvoltage and ensure safe operation of busbar capacitors. However, this method can cause the system to underreact to slight voltage fluctuations when detecting busbar voltage. In particular, when dealing with undervoltage conditions, inaccurate detection can prevent the system from identifying and responding to voltage drops in a timely manner, effectively preventing clipping distortion and leading to poor reliability of the inverter's overvoltage and undervoltage protection. Utility Model Content

[0004] In view of the shortcomings of the existing technology, the inverter bus capacitor overvoltage and undervoltage protection circuit provided in this application can improve the processing accuracy of the bus voltage, thereby improving the reliability of the inverter's overvoltage and undervoltage protection.

[0005] The above-mentioned invention objectives of this application are achieved through the following technical solutions:

[0006] The present application provides an inverter bus capacitor overvoltage and undervoltage protection circuit, which includes a bus voltage sampling module, a bus voltage analysis module, and a bus overvoltage and undervoltage protection execution module. The bus voltage analysis module is connected to the bus voltage sampling module and the bus overvoltage and undervoltage protection execution module, respectively, wherein:

[0007] The bus voltage sampling module is used to obtain a sampling signal of the bus voltage;

[0008] The bus voltage analysis module is configured to determine whether the sampled voltage value of the sampling signal is within a preset voltage range, and output a low level when the sampled voltage value is not within the preset voltage range;

[0009] The bus overvoltage and undervoltage protection execution module is used to control the inverter to stop working and output an alarm signal when it is detected that the bus voltage analysis module outputs a low level.

[0010] By adopting the above technical solution, the bus voltage sampling module obtains the sampling signal of the bus voltage, providing an accurate data basis for subsequent analysis. Then, the bus voltage analysis module judges the sampling signal and can accurately identify voltage anomalies by comparing the sampled voltage value with the preset voltage range. When the sampled voltage value exceeds the preset range, the bus voltage analysis module outputs a low-level signal. This design enables the system to respond quickly to voltage fluctuations. Finally, when the bus overvoltage and undervoltage protection execution module receives the low-level signal, it immediately takes protective measures, controls the inverter to stop working, and outputs an alarm signal. This three-module linkage design improves the accuracy of voltage detection, while taking into account both overvoltage and undervoltage conditions, and comprehensively improves the safety and reliability of the inverter.

[0011] In a preferred example, the present application may be further configured as follows: the bus voltage sampling module includes a voltage dividing unit and a filtering unit, and the filtering unit is connected to the voltage dividing unit and the bus voltage analysis module respectively, wherein:

[0012] A voltage dividing unit, used for dividing the bus voltage to obtain an initial voltage;

[0013] The filtering unit is used to filter the initial voltage to obtain a sampled voltage.

[0014] By adopting the above technical solution, the bus voltage sampling module design achieves accurate bus voltage sampling and signal processing through the combination of a voltage divider and a filter unit. First, the voltage divider divides the bus voltage, converting the high voltage into an initial voltage suitable for subsequent circuit processing. This not only protects subsequent circuit components but also improves sampling safety. Subsequently, the filter unit filters the initial voltage, effectively removing high-frequency noise and interference from the voltage signal, resulting in a more stable and reliable sampled voltage. This design sequence of voltage divider followed by filtering ensures the quality and accuracy of the sampled signal.

[0015] In a preferred example, the present application can be further configured as follows: the voltage dividing unit includes a first resistor, a second resistor, a third resistor, a fourth resistor, and a fifth resistor, wherein:

[0016] The first resistor, the second resistor, the third resistor, the fourth resistor and the fifth resistor are connected in series in sequence, one end of the first resistor is connected to the DC bus, and the series connection point of the fourth resistor and the fifth resistor is connected to the bus voltage analysis module.

[0017] By adopting the above technical solution, the first, second, third, fourth, and fifth resistors are connected in series in sequence to achieve precise voltage division of the bus voltage. This multi-stage voltage division structure first improves the accuracy of the voltage division and allows for more flexible adjustment of the voltage division ratio to meet the needs of different voltage levels.

[0018] In a preferred example, the present application may be further configured as follows: the filtering unit includes a first capacitor, wherein:

[0019] A first end of the first capacitor is connected to a serial connection of the fourth resistor and the fifth resistor, and a second end of the first capacitor is grounded.

[0020] By adopting the above technical solution, the filter unit utilizes a first capacitor design, and through its specific connection method, effectively filters the divided signal. The first end of the first capacitor is connected to the series connection of the fourth and fifth resistors, directly receiving the initial voltage signal from the voltage divider unit, while the second end is grounded, forming a simple and efficient low-pass filter circuit. This structure effectively filters out high-frequency noise and interference, improving the quality of the sampled signal.

[0021] In a preferred example, the present application can be further configured as follows: the bus voltage analysis module includes a voltage comparison unit, a drive unit, and an optocoupler isolation unit, the voltage comparison unit is respectively connected to the bus voltage sampling module and the drive unit, and the optocoupler isolation unit is respectively connected to the drive unit and the bus overvoltage and undervoltage protection execution module, wherein:

[0022] The voltage comparison unit is configured to compare the sampled voltage value of the sampled signal with a first preset voltage value and a second preset voltage value, and output a high level signal when the sampled voltage value is greater than the first preset voltage value or less than the second preset voltage value;

[0023] The driving unit is configured to turn on the input end of the optical coupling isolation unit when receiving the high-level signal;

[0024] The optocoupler isolation unit is used to isolate the bus voltage sampling module and the bus overvoltage and undervoltage protection execution module, and outputs a low level after being turned on.

[0025] By adopting the above technical solution, the bus voltage analysis module achieves precise analysis and safe isolation of the sampled voltage through the coordinated operation of a voltage comparison unit, a driver unit, and an optocoupler isolation unit. First, the voltage comparison unit compares the voltage of the sampled signal with preset upper and lower thresholds (a first preset voltage value and a second preset voltage value). This dual-threshold comparison method enables simultaneous monitoring of overvoltage and undervoltage conditions, improving the accuracy and sensitivity of voltage anomaly detection. When the sampled voltage exceeds the safe range, the voltage comparison unit outputs a high-level signal, quickly triggering subsequent protection mechanisms. Second, upon receiving the high-level signal, the driver unit immediately turns on the input of the optocoupler isolation unit. This design ensures timely and reliable signal transmission. Finally, the optocoupler isolation unit, while providing electrical isolation, converts the high-level signal into a low-level output, providing a clear trigger signal for the bus overvoltage and undervoltage protection execution modules.

[0026] In a preferred example, the present application may be further configured as follows: the voltage comparison unit includes a first comparator and a second comparator, wherein:

[0027] The first preset voltage value is input to the inverting input terminal of the first comparator, the positive input terminal of the first comparator is connected to the bus voltage sampling module, and the output terminal of the first comparator is connected to the driving unit;

[0028] The inverting input terminal of the second comparator is connected to the bus voltage sampling module, the second preset voltage value is input to the positive input terminal of the second comparator, and the output terminal of the second comparator is connected to the driving unit.

[0029] Using this technical solution, the first comparator detects overvoltage conditions. Its inverting input is connected to a first preset voltage value (upper threshold), and its positive input receives a sampling signal from the bus voltage sampling module. When the sampled voltage exceeds the upper threshold, the first comparator outputs a high level. The second comparator detects undervoltage conditions. Its inverting input is connected to the sampling signal, and its positive input is connected to a second preset voltage value (lower threshold). When the sampled voltage falls below the lower threshold, the second comparator outputs a high level. This dual-comparator architecture enables simultaneous monitoring of both overvoltage and undervoltage conditions, significantly improving the comprehensiveness and accuracy of voltage detection. The outputs of both comparators are connected to the drive unit, ensuring that the protection mechanism is triggered promptly in response to either abnormality. This design not only increases the system's sensitivity to voltage fluctuations but also enhances detection reliability and stability.

[0030] In a preferred example, the present application can be further configured as follows: the driving unit includes a sixth resistor, a seventh resistor, an eighth resistor, a first diode, a second diode, and a transistor, wherein:

[0031] A first end of the sixth resistor is connected to a power supply, and a second end of the sixth resistor is connected to the voltage comparison unit;

[0032] The base of the transistor is connected to the first end of the seventh resistor, the second end of the seventh resistor is connected to the second end of the sixth resistor, the collector of the transistor is connected to the optical coupling isolation unit, and the emitter of the transistor is grounded;

[0033] A first end of the eighth resistor is connected to the base of the transistor, and a second end of the eighth resistor is grounded;

[0034] The anode of the first diode is connected to the base of the transistor, and the cathode of the first diode is connected to the first end of the sixth resistor;

[0035] A cathode of the second diode is connected to the first end of the seventh resistor, and an anode of the second diode is grounded.

[0036] By adopting the above technical solution, the design of the drive unit achieves effective processing and amplification of the output signal of the voltage comparison unit through the ingenious combination of the sixth resistor, the seventh resistor, the eighth resistor, the first diode, the second diode and the transistor. First, the sixth resistor connects the power supply and the voltage comparison unit to provide a stable operating voltage for the entire drive circuit. The eighth resistor acts as a base pull-down resistor to ensure that the transistor remains in the off state when there is no signal input, thereby improving the stability of the circuit. The arrangement of the first diode and the second diode forms a protection circuit, wherein the first diode prevents reverse current from damaging the transistor, while the second diode protects the transistor base from negative voltage. This design not only improves the reliability of the drive circuit, but also enhances its anti-interference ability. The collector of the transistor is directly connected to the optocoupler isolation unit. When the transistor is turned on, it can provide sufficient drive current to the optocoupler to ensure effective signal transmission.

[0037] In a preferred example, the present application may be further configured as follows: the optical coupling isolation unit includes an optical coupler, a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, and a second capacitor, wherein:

[0038] The positive input electrode of the optocoupler is connected to the power supply via the ninth resistor, the negative input electrode of the optocoupler is connected to the driving unit, and the positive output electrode of the optocoupler is connected to the power supply via the eleventh resistor;

[0039] A first end of the tenth resistor is connected to the negative input electrode of the optocoupler, and a second end of the tenth resistor is connected to the positive input electrode of the optocoupler;

[0040] A first end of the second capacitor is connected to the positive output electrode of the optocoupler, and a second end of the second capacitor is connected to the negative output electrode of the optocoupler;

[0041] The first end of the twelfth resistor is connected to the bus overvoltage and undervoltage protection execution module, and the second end of the twelfth resistor is connected to the output positive electrode of the optocoupler.

[0042] By adopting the above technical solution, the negative input electrode is directly connected to the drive unit, achieving a fast response. The tenth resistor is connected in parallel to the optocoupler input terminal, which plays a role in current limiting protection and improves the safety and stability of the circuit. The positive output electrode of the optocoupler is connected to the power supply through the eleventh resistor, providing a stable voltage reference for the output signal. The second capacitor is connected in parallel to the output terminal of the optocoupler to form a decoupling filter circuit, which effectively suppresses high-frequency noise and improves the quality of the signal. The twelfth resistor connects the positive output electrode of the optocoupler and the bus overvoltage and undervoltage protection execution module, which plays a role in signal conditioning and impedance matching, ensuring the effective transmission of the signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 A schematic diagram of the structure of an inverter bus capacitor overvoltage and undervoltage protection circuit provided in an embodiment of the present application;

[0044] Figure 2 A schematic structural diagram of a bus voltage sampling module provided in an embodiment of the present application;

[0045] Figure 3 A schematic structural diagram of a bus voltage analysis module provided in an embodiment of the present application. DETAILED DESCRIPTION

[0046] The present application is further described in detail below with reference to the accompanying drawings.

[0047] Reference Figure 1 , is a schematic structural diagram of an inverter bus capacitor overvoltage and undervoltage protection circuit provided in an embodiment of the present application. The circuit includes a bus voltage sampling module, a bus voltage analysis module, and a bus overvoltage and undervoltage protection execution module. The bus voltage analysis module is connected to the bus voltage sampling module and the bus overvoltage and undervoltage protection execution module, respectively.

[0048] Bus voltage sampling module, used to obtain bus voltage sampling signal;

[0049] The bus voltage analysis module is used to determine whether the sampling voltage value of the sampling signal is within a preset voltage range, and output a low level when the sampling voltage value is not within the preset voltage range;

[0050] The bus overvoltage and undervoltage protection execution module is used to control the inverter to stop working and output an alarm signal when it detects that the bus voltage analysis module outputs a low level.

[0051] This embodiment proposes an inverter bus capacitor overvoltage and undervoltage protection circuit. This circuit primarily consists of a bus voltage sampling module, a bus voltage analysis module, and a bus overvoltage and undervoltage protection execution module. These three modules work together to implement overvoltage and undervoltage protection for the inverter bus capacitor.

[0052] The bus voltage sampling module is responsible for acquiring the bus voltage sampling signal. Through the sampling module, we can monitor the changes in bus voltage in real time, providing reliable data support for subsequent analysis and judgment.

[0053] The bus voltage analysis module receives signals from the sampling module and evaluates the sampled voltage value. Its core function is to determine whether the sampled voltage value is within a preset safety voltage range. This preset range is determined based on the inverter's operating characteristics and safety requirements. If the sampled voltage value exceeds this range, either exceeding the upper limit (overvoltage) or falling below the lower limit (undervoltage), the bus voltage analysis module outputs a low-level signal.

[0054] The bus overvoltage and undervoltage protection execution module takes immediate action upon receiving a low-level signal from the bus voltage analysis module. Its primary task is to shut down the inverter and simultaneously output an alarm signal. By rapidly shutting down the inverter, potential damage to the equipment caused by persistent overvoltage or undervoltage conditions can be effectively prevented. Furthermore, the output of the alarm signal promptly alerts operators, enabling them to quickly intervene and take necessary measures.

[0055] The inverter bus capacitor overvoltage and undervoltage protection circuit utilizes three steps: sampling, analysis, and execution. The bus voltage sampling module enables real-time monitoring of the bus voltage, enabling rapid response to voltage anomalies. The bus voltage analysis module, with its preset voltage range, allows the system to flexibly adapt to the protection requirements of different inverter types. The bus overvoltage and undervoltage protection execution module, responding to the low-level signal output by the bus voltage analysis module, promptly stops the inverter and issues an alarm, effectively reducing the risk of equipment damage and improving overall system safety and stability.

[0056] The specific structure of the bus voltage sampling module in the embodiment of the present application is described in detail below. Figure 2 , is a structural diagram of a bus voltage sampling module provided in an embodiment of the present application.

[0057] The bus voltage sampling module in the figure includes a voltage divider unit and a filter unit. The filter unit is connected to the voltage divider unit and the bus voltage analysis module respectively, where:

[0058] A voltage dividing unit, used for dividing the bus voltage to obtain an initial voltage;

[0059] The filtering unit is used to filter the initial voltage to obtain a sampled voltage.

[0060] The voltage divider's primary function is to divide the bus voltage to obtain an initial voltage. This step is necessary because the inverter's bus voltage is typically high, and direct measurement may exceed the tolerance or measurement range of subsequent circuit components. By using voltage divider processing, the high voltage can be reduced to a level suitable for subsequent circuit processing while maintaining a linear relationship between voltage changes.

[0061] After obtaining the initial voltage, the filtering unit then filters it to obtain the sampled voltage. The necessity of filtering is that the bus voltage may contain high-frequency noise or interference signals, which may come from the switching operation of the inverter, external electromagnetic interference, etc.

[0062] In an optional implementation, the voltage dividing unit includes a first resistor, a second resistor, a third resistor, a fourth resistor, and a fifth resistor, wherein:

[0063] The first resistor, the second resistor, the third resistor, the fourth resistor and the fifth resistor are connected in series in sequence. One end of the first resistor is connected to the DC bus, and the series connection point of the fourth resistor and the fifth resistor is connected to the bus voltage analysis module.

[0064] The voltage divider unit adopts a design of five resistors in series, including a first resistor, a second resistor, a third resistor, a fourth resistor, and a fifth resistor. Using multiple resistors in series for voltage division, rather than simply two resistors for voltage division, is mainly to improve the accuracy and reliability of voltage division. In high-voltage applications, the use of multi-stage voltage division can disperse the voltage more evenly, reduce the voltage on each resistor, and thus improve the stability and life of the entire voltage divider network. At the same time, multi-stage voltage division can also reduce the overall voltage division ratio error caused by the deviation of a single resistor value, thereby improving the accuracy of voltage division.

[0065] In a specific implementation, the first, second, third, fourth, and fifth resistors are connected in series in that order. One end of the first resistor is directly connected to the DC bus, which serves as the high-voltage input for the entire voltage divider network. The series connection between the fourth and fifth resistors is connected to the bus voltage analysis module, serving as the output after voltage division. This connection ensures that the high voltage is gradually reduced, ultimately obtaining a voltage value suitable for use by the subsequent analysis module at the connection between the fourth and fifth resistors. The voltage divider unit design using five series resistors provides a stable and accurate input signal for the subsequent voltage analysis module.

[0066] In an optional embodiment, the filtering unit includes a first capacitor, wherein:

[0067] A first end of the first capacitor is connected to a serial connection point of the fourth resistor and the fifth resistor, and a second end of the first capacitor is grounded.

[0068] The main purpose of the filtering unit is to remove high-frequency noise and interference from the voltage-divided signal, resulting in a more stable and smooth voltage signal. In inverter systems, due to high switching frequencies and complex electromagnetic interference, the original sampled signal often contains various high-frequency components, which can affect the accuracy of subsequent voltage analysis. By adding a filtering unit, these unnecessary high-frequency components can be effectively suppressed, providing a more reliable voltage sample value.

[0069] In a specific implementation, the first end of the first capacitor is connected to the series connection of the fourth and fifth resistors in the voltage divider unit. This connection point is the voltage output point after voltage division, which is the signal source that needs to be filtered. The second end of the first capacitor is directly grounded, forming a typical RC low-pass filter circuit structure. The filter unit design using a single first capacitor effectively removes high-frequency noise and interference by forming an RC low-pass filter with the voltage divider network, providing a stable and reliable voltage sampling signal.

[0070] The filter unit effectively attenuates high-frequency noise and interference, making the sampled voltage more stable and reducing the impact of voltage fluctuations on subsequent analysis. Furthermore, since the filter unit uses only one capacitor, the circuit structure is simple, making it easy to implement and maintain, while also reducing costs.

[0071] The specific structure of the bus voltage analysis module in the embodiment of the present application is described in detail below. Figure 3 , is a structural diagram of a bus voltage analysis module provided in an embodiment of the present application.

[0072] The bus voltage analysis module in the figure includes a voltage comparison unit, a drive unit, and an optocoupler isolation unit. The voltage comparison unit is connected to the bus voltage sampling module and the drive unit respectively. The optocoupler isolation unit is connected to the drive unit and the bus overvoltage and undervoltage protection execution module respectively.

[0073] a voltage comparison unit, configured to compare a sampled voltage value of the sampled signal with a first preset voltage value and a second preset voltage value, and output a high-level signal when the sampled voltage value is greater than the first preset voltage value or less than the second preset voltage value;

[0074] A driving unit, configured to turn on the input end of the optocoupler isolation unit when receiving a high-level signal;

[0075] The optocoupler isolation unit is used to isolate the bus voltage sampling module and the bus overvoltage and undervoltage protection execution module, and outputs a low level after being turned on.

[0076] The voltage comparison unit's primary function is to compare the sampled voltage of the sampled signal with a preset threshold. A first preset voltage value (overvoltage threshold, shown as VH in the figure) and a second preset voltage value (undervoltage threshold, shown as VL in the figure) are set. When the sampled voltage is greater than the first preset voltage value or less than the second preset voltage value, the voltage comparison unit outputs a high-level signal, accurately detecting abnormal bus voltage conditions, whether overvoltage or undervoltage.

[0077] When the voltage comparator detects an anomaly and outputs a high-level signal, the driver unit is activated. The driver unit utilizes switching elements such as transistors or MOSFETs. Its primary function is to convert the voltage comparator's logic signal into sufficient drive current to activate the optocoupler isolation unit's input (LED). The optocoupler isolation unit achieves electrical isolation through photoelectric coupling, effectively separating the bus voltage sampling module on the high-voltage side from the protection execution module on the low-voltage side. In inverter systems, the bus voltage is typically at a high voltage, while the control and protection circuits operate at a low voltage. Without proper isolation, electrical faults or transients on the high-voltage side could directly affect sensitive circuits on the low-voltage side, causing serious safety hazards and equipment damage. Furthermore, the optocoupler isolation unit outputs a low level when conducting. Upon detecting this low level, the subsequent bus overvoltage and undervoltage protection execution modules control the inverter to shut down and output an alarm signal.

[0078] In an optional implementation, the voltage comparison unit includes a first comparator and a second comparator, wherein:

[0079] A first preset voltage value is input to the inverting input terminal of the first comparator, a positive input terminal of the first comparator is connected to the bus voltage sampling module, and an output terminal of the first comparator is connected to the driving unit;

[0080] The inverting input terminal of the second comparator is connected to the bus voltage sampling module, the positive input terminal of the second comparator inputs the second preset voltage value, and the output terminal of the second comparator is connected to the driving unit.

[0081] In this embodiment, the voltage comparison unit is designed using two comparators, namely a first comparator and a second comparator. This dual comparator structure can simultaneously monitor the overvoltage and undervoltage states of the bus voltage, providing comprehensive voltage protection for the inverter system.

[0082] The first comparator is primarily responsible for detecting overvoltage conditions. Its inverting input is connected to a first preset voltage value, which represents the system's maximum allowable voltage threshold. Its positive input is directly connected to the bus voltage sampling module, receiving real-time sampled bus voltage values. When the sampled voltage exceeds the preset overvoltage threshold, the first comparator's output generates a high-level signal. This connection ensures that the protection mechanism is quickly triggered as soon as the bus voltage exceeds the upper safety limit.

[0083] The second comparator monitors undervoltage conditions. Unlike the first comparator, its inverting input is connected to the bus voltage sampling module, while its positive input receives a second preset voltage value, representing the system's minimum allowable voltage threshold. When the sampled voltage falls below this undervoltage threshold, the second comparator's output generates a high-level signal. This configuration provides a timely alarm when voltage drops abnormally, preventing system failures caused by undervoltage.

[0084] The outputs of both comparators are connected to the driver unit. This design allows the driver unit to quickly activate subsequent protection measures in both overvoltage and undervoltage conditions. This parallel output structure effectively forms a logical "OR" relationship, allowing the system to respond if any abnormal condition occurs.

[0085] The voltage comparison unit design incorporates both a first and second comparator, enabling comprehensive bus voltage monitoring while also improving system response speed and reliability through clever circuit configuration. This provides the entire inverter bus capacitor overvoltage and undervoltage protection system with precise and rapid voltage anomaly detection, significantly enhancing system safety and stability.

[0086] In an optional implementation, the driving unit includes a sixth resistor, a seventh resistor, an eighth resistor, a first diode, a second diode, and a transistor, wherein:

[0087] A first end of the sixth resistor is connected to the power supply, and a second end of the sixth resistor is connected to the voltage comparison unit;

[0088] The base of the transistor is connected to the first end of the seventh resistor, the second end of the seventh resistor is connected to the second end of the sixth resistor, the collector of the transistor is connected to the optocoupler isolation unit, and the emitter of the transistor is grounded;

[0089] A first end of the eighth resistor is connected to the base of the transistor, and a second end of the eighth resistor is grounded;

[0090] The anode of the first diode is connected to the base of the transistor, and the cathode of the first diode is connected to the first end of the sixth resistor;

[0091] The cathode of the second diode is connected to the first end of the seventh resistor, and the anode of the second diode is grounded.

[0092] The driver unit is designed using a complex and sophisticated circuit structure, including transistors, multiple resistors, and diodes. This design ensures that the signal received from the voltage comparator is correctly amplified and converted to reliably drive the optocoupler isolation unit, while also providing the necessary protection and stability.

[0093] The core of the driver unit is a transistor switching circuit. The transistor's base is connected to the output of the voltage comparator via a seventh resistor. This connection allows the comparator's output signal to control the transistor's conduction state. A sixth resistor, connected between the power supply and the voltage comparator's output, acts as a pull-up resistor, ensuring the comparator output remains high when no signal is input.

[0094] The transistor's collector is directly connected to the optocoupler isolation unit. When the transistor is turned on, it provides sufficient drive current for the optocoupler's LED. The transistor's emitter is grounded. This common-emitter configuration provides excellent current amplification. The eighth resistor, connected between the transistor's base and ground, stabilizes the bias voltage and prevents false triggering due to ambient noise.

[0095] The first and second diodes provide protection in the circuit. The first diode's anode is connected to the transistor's base, and its cathode is connected to the positive power supply terminal. This configuration prevents the base voltage from exceeding the power supply voltage, protecting the transistor from reverse breakdown. The second diode, connected between the seventh resistor and ground, clamps the input signal, preventing negative voltage from damaging the transistor.

[0096] The driver unit not only accurately converts the logic signal from the voltage comparator into the current required to drive the optocoupler isolation unit, but also provides the necessary signal conditioning and protection functions. This design enhances the reliability and stability of the entire protection system, ensuring that the protection mechanism is triggered quickly and reliably when a voltage anomaly is detected.

[0097] In an optional implementation, the optocoupler isolation unit includes an optocoupler, a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, and a second capacitor, wherein:

[0098] The positive input electrode of the optocoupler is connected to the power supply via the ninth resistor, the negative input electrode of the optocoupler is connected to the driving unit, and the positive output electrode of the optocoupler is connected to the power supply via the eleventh resistor;

[0099] A first end of the tenth resistor is connected to the negative input electrode of the optocoupler, and a second end of the tenth resistor is connected to the positive input electrode of the optocoupler;

[0100] A first end of the second capacitor is connected to the positive output electrode of the optocoupler, and a second end of the second capacitor is connected to the negative output electrode of the optocoupler;

[0101] A first end of the twelfth resistor is connected to the bus overvoltage and undervoltage protection execution module, and a second end of the twelfth resistor is connected to the output positive electrode of the optocoupler.

[0102] In this embodiment, the design of the optocoupler isolation unit utilizes a carefully constructed circuit structure, including an optocoupler, multiple resistors, and a capacitor. The optocoupler achieves photoelectric conversion of electrical signals through an internal light-emitting diode and a photosensor, thereby transmitting signals while maintaining electrical isolation. The positive input of the optocoupler is connected to the power supply through a ninth resistor, which acts as a current limiter to protect the light-emitting diode from damage caused by excessive current. The negative input is directly connected to the driver unit, receiving control signals from the driver unit.

[0103] The tenth resistor is connected between the positive and negative input terminals of the optocoupler, forming a parallel branch. This resistor provides a stable bias current for the LED, ensuring it remains reliably off when no signal is input, improving the system's noise immunity. It also speeds up the LED's turn-off and improves the optocoupler's dynamic response.

[0104] At the optocoupler's output, an eleventh resistor acts as a pull-up resistor, connected between the positive output terminal and the power supply. This resistor ensures that the output remains high when the optocoupler is inactive. When the optocoupler is active, the output is pulled low, generating a low-level signal. This design aligns with the previously mentioned low-level trigger protection mechanism, ensuring reliable signal transmission.

[0105] The second capacitor, connected in parallel with the optocoupler's output, filters out high-frequency noise and transient interference. During fast switching, this capacitor smooths the edges of the output signal, reducing electromagnetic interference. It also improves the system's anti-interference capabilities, preventing false triggering caused by external electromagnetic interference.

[0106] The twelfth resistor, connected between the optocoupler's positive output terminal and the busbar overvoltage and undervoltage protection module, provides current limiting and impedance matching. It prevents damage to the optocoupler in the event of an output short circuit or abnormal load. It also adjusts the output signal's rise and fall times, optimizing signal transmission quality.

[0107] The optocoupler isolation unit not only reliably isolates high and low voltage systems but also accurately transmits control signals, while also exhibiting excellent anti-interference capabilities and dynamic response characteristics. This design greatly enhances the reliability and stability of the entire protection system, ensuring that the protection mechanism is safely and quickly triggered when voltage anomalies are detected.

[0108] The embodiments of this specific implementation method are all preferred embodiments of the present utility model and are not intended to limit the scope of protection of the present utility model. Therefore, any equivalent changes made based on the structure, shape, and principle of the present utility model should be included in the scope of protection of the present utility model.

Claims

1. An inverter bus capacitor overvoltage and undervoltage protection circuit, characterized in that: The circuit includes a bus voltage sampling module, a bus voltage analysis module, and a bus overvoltage and undervoltage protection execution module. The bus voltage analysis module is connected to the bus voltage sampling module and the bus overvoltage and undervoltage protection execution module respectively, wherein: The bus voltage sampling module is used to obtain a sampling signal of the bus voltage; The bus voltage analysis module is configured to determine whether the sampled voltage value of the sampling signal is within a preset voltage range, and output a low level when the sampled voltage value is not within the preset voltage range; The bus voltage analysis module includes a voltage comparison unit, a drive unit, and an optocoupler isolation unit. The voltage comparison unit is connected to the bus voltage sampling module and the drive unit respectively. The optocoupler isolation unit is connected to the drive unit and the bus overvoltage and undervoltage protection execution module respectively. The voltage comparison unit is configured to compare the sampled voltage value of the sampled signal with a first preset voltage value and a second preset voltage value, and output a high level signal when the sampled voltage value is greater than the first preset voltage value or less than the second preset voltage value; The driving unit is configured to turn on the input end of the optical coupling isolation unit when receiving the high-level signal; The optical coupling isolation unit is used to isolate the bus voltage sampling module and the bus overvoltage and undervoltage protection execution module, and output a low level after being turned on; The bus overvoltage and undervoltage protection execution module is used to control the inverter to stop working and output an alarm signal when it is detected that the bus voltage analysis module outputs a low level.

2. The inverter bus capacitor overvoltage and undervoltage protection circuit according to claim 1, characterized in that: The bus voltage sampling module includes a voltage dividing unit and a filtering unit, and the filtering unit is connected to the voltage dividing unit and the bus voltage analysis module respectively, wherein: A voltage dividing unit, used for dividing the bus voltage to obtain an initial voltage; The filtering unit is used to filter the initial voltage to obtain a sampled voltage.

3. The inverter bus capacitor overvoltage and undervoltage protection circuit according to claim 2, characterized in that: The voltage dividing unit includes a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor, wherein: The first resistor, the second resistor, the third resistor, the fourth resistor and the fifth resistor are connected in series in sequence, one end of the first resistor is connected to the DC bus, and the series connection point of the fourth resistor and the fifth resistor is connected to the bus voltage analysis module.

4. The inverter bus capacitor overvoltage and undervoltage protection circuit according to claim 3, characterized in that: The filtering unit includes a first capacitor, wherein: A first end of the first capacitor is connected to a serial connection of the fourth resistor and the fifth resistor, and a second end of the first capacitor is grounded.

5. The inverter bus capacitor overvoltage and undervoltage protection circuit according to claim 1, characterized in that: The voltage comparison unit includes a first comparator and a second comparator, wherein: The first preset voltage value is input to the inverting input terminal of the first comparator, the positive input terminal of the first comparator is connected to the bus voltage sampling module, and the output terminal of the first comparator is connected to the driving unit; The inverting input terminal of the second comparator is connected to the bus voltage sampling module, the second preset voltage value is input to the positive input terminal of the second comparator, and the output terminal of the second comparator is connected to the driving unit.

6. The inverter bus capacitor overvoltage and undervoltage protection circuit according to claim 1, characterized in that: The driving unit includes a sixth resistor, a seventh resistor, an eighth resistor, a first diode, a second diode and a transistor, wherein: A first end of the sixth resistor is connected to a power supply, and a second end of the sixth resistor is connected to the voltage comparison unit; The base of the transistor is connected to the first end of the seventh resistor, the second end of the seventh resistor is connected to the second end of the sixth resistor, the collector of the transistor is connected to the optical coupling isolation unit, and the emitter of the transistor is grounded; A first end of the eighth resistor is connected to the base of the transistor, and a second end of the eighth resistor is grounded; The anode of the first diode is connected to the base of the transistor, and the cathode of the first diode is connected to the first end of the sixth resistor; A cathode of the second diode is connected to the first end of the seventh resistor, and an anode of the second diode is grounded.

7. The inverter bus capacitor overvoltage and undervoltage protection circuit according to claim 1, characterized in that: The optical coupling isolation unit includes an optical coupler, a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, and a second capacitor, wherein: The positive input electrode of the optocoupler is connected to the power supply via the ninth resistor, the negative input electrode of the optocoupler is connected to the driving unit, and the positive output electrode of the optocoupler is connected to the power supply via the eleventh resistor; A first end of the tenth resistor is connected to the negative input electrode of the optocoupler, and a second end of the tenth resistor is connected to the positive input electrode of the optocoupler; A first end of the second capacitor is connected to the positive output electrode of the optocoupler, and a second end of the second capacitor is connected to the negative output electrode of the optocoupler; The first end of the twelfth resistor is connected to the bus overvoltage and undervoltage protection execution module, and the second end of the twelfth resistor is connected to the output positive electrode of the optocoupler.

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