A protection level adjustable circuit for a frequency converter

Abstract

An adjustable protection level circuit for a frequency converter, belonging to the field of frequency converters, includes: a voltage acquisition circuit, a reference voltage circuit, and a comparison voltage circuit. The voltage acquisition circuit is used to acquire the bus voltage of the frequency converter and use it as the acquisition voltage. The input terminal of the reference voltage circuit is connected to the CPU to receive the reference voltage output by the CPU. The input terminal of the comparison voltage circuit is connected to the output terminals of the voltage acquisition circuit and the reference voltage circuit respectively, and is used to compare the acquisition voltage with the reference voltage and trigger protection action according to the comparison result. This application achieves accurate protection of the protected object (such as voltage and current) by flexibly adjusting the output reference voltage by the CPU through software parameter setting, which is not affected by the temperature of the device error and does not require the replacement of hardware devices.

Description

Technical Field

[0001] This utility model relates to an adjustable protection level circuit for a frequency converter, belonging to the field of frequency converters. Background Technology

[0002] In existing inverter protection technologies, overvoltage and overcurrent protection typically rely on resistor voltage division to generate a comparator reference voltage, which is then compared with the detected voltage to trigger protection action. However, this method has several problems: First, adjusting the protection level for different input voltage levels requires changing component parameters, which is cumbersome and prone to errors. Second, resistor voltage division is susceptible to component errors and temperature variations, leading to reference voltage deviations and affecting protection accuracy. Third, in traditional methods, finished boards with different reference voltage requirements cannot be shared during production, increasing production costs and inventory management difficulties. Manually changing components can also cause problems such as poor soldering and short circuits. These issues limit the flexibility, accuracy, and reliability of inverter protection circuits. Utility Model Content

[0003] In view of the shortcomings of the existing technology, the purpose of this utility model is to provide an adjustable protection level circuit for frequency converters, so as to solve the technical problem that the existing frequency converter protection technology relies on resistor voltage division detection and has poor versatility.

[0004] To achieve the above objectives, this utility model provides a protection level adjustable circuit for a frequency converter, comprising: The voltage acquisition circuit is used to acquire the bus voltage of the frequency converter and use it as the acquired voltage. The reference voltage circuit has its input terminal connected to the CPU to receive the reference voltage output by the CPU. The voltage comparison circuit has its input terminals connected to the output terminals of the voltage acquisition circuit and the reference voltage circuit, respectively. It is used to compare the acquired voltage with the reference voltage and trigger protection actions based on the comparison result.

[0005] Furthermore, the voltage acquisition circuit includes a resistor voltage divider circuit and a first filter circuit. The resistor voltage divider circuit is used to divide the bus voltage of the frequency converter, and the first filter circuit includes a capacitor C1 and a resistor R1, which is used to filter the acquired voltage after voltage division.

[0006] Furthermore, the input terminal of the reference voltage circuit is connected to the CPU's AD port, and is used to set different levels of reference voltage according to the CPU's parameters.

[0007] Furthermore, the reference voltage circuit also includes a second filter circuit, which includes a resistor R6 and a capacitor C2, for filtering the reference voltage to ensure its stability and accuracy.

[0008] Furthermore, the voltage comparison circuit includes a comparator circuit and an output circuit. The comparator circuit is used to compare the acquired voltage with the reference voltage and output a corresponding signal according to the comparison result. The output circuit processes the signal output by the comparator circuit and sends the processed signal to the interrupt port of the CPU to trigger a protection action.

[0009] Furthermore, the comparator circuit includes a comparator chip IC1, and its specific connection method is as follows: Pin 1 of comparator chip IC1 is the negative input terminal, which is connected to the output terminal of the voltage acquisition circuit; Pin 3 of comparator chip IC1 is the positive input terminal, which is connected to the output terminal of the reference voltage circuit. Pin 2 of comparator chip IC1 is grounded; Pin 5 of comparator chip IC1 is connected to the power supply voltage and grounded through capacitor C3 to achieve power supply decoupling; Pin 4 of the comparator chip IC1 is the output terminal, which is connected to the output circuit.

[0010] Furthermore, the output circuit includes resistors R4 and R5 and capacitor C4. One end of resistor R4 is connected to the output terminal of the comparator circuit, and the other end is connected to the power supply voltage. Resistor R5 and capacitor C4 are connected in series and grounded, which are used to filter the output signal of the comparator circuit and send the processed signal to the interrupt port of the CPU.

[0011] Furthermore, the comparison voltage circuit triggers a protection action based on the comparison result. The specific comparison process is as follows: When the acquired voltage is greater than the reference voltage, the output circuit sends a low-level signal to the CPU, triggering the CPU to execute protection actions, including stopping the inverter output, recording fault information, and issuing an alarm signal. When the acquired voltage is less than or equal to the reference voltage, the output circuit maintains a high-level signal, and the CPU does not perform any protection actions.

[0012] The beneficial effects of this utility model are: This application enables precise protection of objects (such as voltage and current) by allowing the CPU to flexibly adjust the output reference voltage through software parameter settings. This is unaffected by temperature variations due to component errors and requires no hardware replacement. The design allows finished boards with different reference voltage requirements to be shared, significantly reducing inventory types and costs. Simultaneously, it simplifies the production process, improves production efficiency, and reduces the potential risks associated with manually changing components. Attached Figure Description

[0013] Other features, objects, and advantages of this invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a schematic diagram of the structure of a protection level adjustable circuit for a frequency converter according to the present invention; Figure 2 This is a schematic diagram of the circuit structure for inverter bus voltage detection in Embodiment 2. Figure 3 This is a schematic diagram of the protection circuit of an existing frequency converter.

[0014] The attached figures are labeled as follows: 1. Voltage acquisition circuit; 2. Reference voltage circuit; 3. Comparison voltage circuit. Detailed Implementation

[0015] To make the technical means, creative features, objectives and effects of this utility model easier to understand, the present utility model will be further described below in conjunction with specific embodiments.

[0016] like Figure 1 As shown, this utility model provides a technical solution for an adjustable protection level circuit for a frequency converter, which includes: Voltage acquisition circuit 1 is used to acquire the bus voltage of the frequency converter and use it as the acquired voltage. Reference voltage circuit 2, whose input terminal is connected to the CPU, is used to receive the reference voltage output by the CPU; The voltage comparison circuit 3 has its input terminals connected to the output terminals of the voltage acquisition circuit 1 and the reference voltage circuit 2, respectively. It is used to compare the acquired voltage with the reference voltage and trigger protection actions based on the comparison result.

[0017] To improve the stability and accuracy of the acquired voltage, the voltage acquisition circuit 1 includes a resistor voltage divider circuit and a first filter circuit. The resistor voltage divider circuit is used to divide the bus voltage of the frequency converter. The first filter circuit includes a capacitor C1 and a resistor R1, which is used to filter the acquired voltage after voltage division, thereby reducing the impact of noise and voltage fluctuations on the acquired voltage.

[0018] In order to output a high-precision reference voltage, the input terminal of the reference voltage circuit 2 is connected to the CPU's AD port, which is used to set different levels of reference voltage according to the CPU's parameters, thereby realizing precise protection for frequency converters with different input voltage levels.

[0019] To further improve the accuracy of the reference voltage, the reference voltage circuit 2 also includes a second filter circuit, which includes a resistor R6 and a capacitor C2, for filtering the reference voltage to ensure its stability and accuracy, and reduce the impact of device errors and temperature changes on the reference voltage.

[0020] To achieve accurate comparison between the reference voltage and the acquired voltage, the comparison voltage circuit 3 includes a comparator circuit and an output circuit. The comparator circuit compares the acquired voltage with the reference voltage and outputs a corresponding signal based on the comparison result. The output circuit processes the signal output by the comparator circuit and sends the processed signal to the interrupt port of the CPU to trigger a protection action, ensuring that the inverter can quickly stop output in abnormal situations and protect the equipment safety.

[0021] To ensure the stability and reliability of the comparator output signal, the output circuit includes resistors R4 and R5 and capacitor C4. One end of resistor R4 is connected to the output terminal of the comparator circuit, and the other end is connected to the power supply voltage. Resistor R5 and capacitor C4 are connected in series and grounded. This is used to filter the output signal of the comparator circuit and send the processed signal to the interrupt port of the CPU, thereby reducing the impact of high-frequency noise and voltage fluctuations on the protection logic and improving the anti-interference capability of the entire protection circuit.

[0022] Example 1: In this application, comparator IC1 is selected from comparator chips with high precision and low power consumption, including but not limited to models such as BA8391G, LMV311, MAX9117, or TLV3201. These comparator chips all have 5-pin packages, which can meet the circuit design requirements of this application. Different package types (such as SO-8, SOIC-14, etc.) can be selected according to actual application requirements, and the pins can be adjusted appropriately. The following describes in detail the specific connection method of comparator chip IC1 and its function in the circuit, using the 5-pin package as an example.

[0023] Pin 1 of comparator chip IC1 is the negative input terminal, which is connected to the output terminal of voltage acquisition circuit 1. Voltage acquisition circuit 1 divides the inverter bus voltage through a resistor voltage divider circuit, and then filters the divided acquisition voltage through a filter circuit (including capacitor C1 and resistor R1) to reduce the influence of noise and voltage fluctuations. Finally, a stable acquisition voltage is input to pin 1 of comparator chip IC1. Pin 3 of comparator chip IC1 is the positive input terminal, which is connected to the output terminal of reference voltage circuit 2. The input terminal of reference voltage circuit 2 is connected to the CPU's AD port. According to the CPU's parameter settings, it outputs different levels of reference voltage. The reference voltage is filtered by the second filter circuit (including resistor R6 and capacitor C2) to ensure the stability and accuracy of the reference voltage. The processed reference voltage is then input to pin 3 of comparator chip IC1. Pin 2 of comparator chip IC1 is grounded to provide a reference ground potential for comparator chip IC1 and ensure the normal operation of the comparator. Pin 5 of comparator chip IC1 is connected to the power supply voltage and grounded through capacitor C3 to filter out noise and ripple in the power supply, ensuring the stability of the power supply voltage and thus improving the comparator's operating accuracy. Pin 4 of comparator chip IC1 is the output terminal, which is connected to the output circuit. The output circuit includes resistor R4, resistor R5, and capacitor C4. One end of resistor R4 is connected to pin 4 of comparator chip IC1, and the other end is connected to the power supply voltage VCC. It is used to pull the comparator's output signal to a high level. Resistor R5 and capacitor C4 are connected in series and grounded. They are used to filter the comparator's output signal to reduce the influence of high-frequency noise and voltage fluctuations. The processed signal is then sent to the CPU's interrupt port to trigger protection actions.

[0024] Example 2: like Figure 2 As shown in the figure, this embodiment takes the inverter bus voltage detection as an example to explain in detail the specific implementation of the circuit and the specific implementation of the protection logic.

[0025] (1) Specific implementation of the circuit: 1. Voltage generation: The voltage divider circuit divides the voltage through resistors R10, R11, R12, R13, R14, and R15 to obtain the bus voltage.

[0026] Among them, resistors R10-R15 are connected in series between the bus voltage and ground to divide the bus voltage to a voltage range suitable for the comparator input. The voltage across resistor R15 is the bus sampling voltage, which is input to voltage sampling circuit 1. The sampling voltage after voltage division is filtered by a filter circuit composed of capacitor C1 and resistor R1 to reduce the influence of noise and voltage fluctuation.

[0027] 2. Reference Voltage Generation: The reference voltage is output from the CPU's AD port. Different levels of reference voltage are output according to the CPU's parameter settings. For example, the reference voltage is set to 1.5V for AC220V input and 3.0V for AC380V input. The reference voltage is filtered by a second filter circuit consisting of resistor R6 and capacitor C2 to ensure its stability and accuracy.

[0028] 3. Comparison Protection: The comparison voltage circuit 3 compares the acquired voltage with the reference voltage through the comparator circuit, and outputs the processed signal through the output circuit according to the comparison result, which is sent to the CPU interrupt port to trigger the protection action.

[0029] (2) Specific implementation of protection logic: 1. When the sampled voltage is greater than the reference voltage, the output terminal (pin 4) of comparator chip IC1 outputs a low-level signal. The output circuit sends a low-level signal to the CPU, triggering the CPU to execute a protection action. Specific protection actions include: Stop inverter output: After the CPU receives a low-level signal, it immediately stops the inverter output to prevent overvoltage or overcurrent from damaging the equipment; Record fault information: The CPU records fault information, including the time of the fault occurrence, the sampled voltage value, the reference voltage value, etc., to facilitate subsequent fault diagnosis and maintenance; Issue an alarm signal: The CPU issues an alarm signal to notify the operator to take appropriate measures, such as checking the power supply voltage and repairing the faulty equipment.

[0030] 2. When the sampled voltage is less than or equal to the reference voltage, the output terminal (pin 4) of the comparator chip IC1 outputs a high-level signal. The output circuit maintains a high-level signal, the CPU does not perform protection actions, and the frequency converter operates normally.

[0031] (3) The overall workflow of this embodiment is as follows: 1. Initialization: When the circuit starts, the CPU initializes the reference voltage circuit 2 and sets the output value of the reference voltage according to the input voltage level. At the same time, the voltage acquisition circuit 1 acquires the bus voltage of the frequency converter and performs filtering processing through the filter circuit.

[0032] 2. Real-time monitoring: The voltage comparison circuit 3 compares the acquired voltage and the reference voltage in real time. The output signal of the comparator is filtered by the output circuit and then sent to the interrupt port of the CPU.

[0033] 3. Protection action triggered: When the sampled voltage is greater than the reference voltage, the comparator outputs a low-level signal, triggering the CPU to execute protection actions. The CPU's protection actions include stopping the inverter output, recording fault information, and issuing an alarm signal.

[0034] 4. Return to normal: Once the fault is cleared, the voltage returns to normal, the comparator outputs a high-level signal, the CPU stops its protection action, and the inverter resumes normal operation.

[0035] like Figure 3 The diagram shows the circuit structure of the protection circuit of an existing frequency converter. The reference voltage of the comparator is usually obtained from the power supply voltage VCC through a resistor divider (such as resistors R2 and R3).

[0036] While this method is simple, it has some significant limitations. Firstly, the resistance value itself may have errors and is easily affected by temperature changes, leading to fluctuations in the comparator's reference voltage. This can affect the accurate protection of the sampled voltage (such as voltage or current). Secondly, when faced with different input voltage levels, overvoltage and overcurrent protection levels often need adjustment. Traditionally, changing the reference voltage can only be achieved by modifying component parameters. This is not only cumbersome but also introduces other problems. For example, in SMT (Surface Mount Technology) manufacturing, finished boards with different reference voltage requirements cannot be shared, resulting in a wide variety of finished boards and consuming significant inventory. Manually changing components can easily lead to issues like cold solder joints and short circuits, affecting circuit reliability and stability. These problems, to some extent, limit the flexibility and reliability of existing technologies in practical applications.

[0037] Therefore, this application achieves precise protection for the protected object (such as voltage and current) by flexibly adjusting the output reference voltage through software parameter settings, unaffected by temperature-related component errors and without requiring hardware replacement. This design allows finished boards with different reference voltage requirements to be shared, significantly reducing inventory types and costs. Simultaneously, it simplifies the production process, improves production efficiency, reduces the potential risks associated with manual component changes, and provides a technical solution different from traditional transmission methods.

[0038] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. It will be apparent to those skilled in the art that this utility model is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or basic characteristics of this utility model. Therefore, the embodiments should be considered exemplary and non-limiting in all respects. The scope of this utility model is defined by the appended claims rather than the foregoing description, and thus all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this utility model. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0039] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A protection level adjustable circuit for a frequency converter, characterized in that: It includes: Voltage acquisition circuit (1) is used to acquire the bus voltage of the frequency converter and use it as the acquisition voltage; The reference voltage circuit (2) has its input terminal connected to the CPU and is used to receive the reference voltage output by the CPU. The voltage comparison circuit (3) has its input terminals connected to the output terminals of the voltage acquisition circuit (1) and the reference voltage circuit (2), respectively. It is used to compare the acquired voltage with the reference voltage and trigger the protection action according to the comparison result.

2. The adjustable protection level circuit for a frequency converter according to claim 1, characterized in that: The voltage acquisition circuit (1) includes a resistor voltage divider circuit and a first filter circuit. The resistor voltage divider circuit is used to divide the bus voltage of the frequency converter. The first filter circuit includes a capacitor C1 and a resistor R1, which is used to filter the acquired voltage after voltage division.

3. The adjustable protection level circuit for a frequency converter according to claim 1, characterized in that: The input terminal of the reference voltage circuit (2) is connected to the CPU's AD port and is used to set different levels of reference voltage according to the CPU's parameters.

4. The adjustable protection level circuit for a frequency converter according to claim 3, characterized in that: The reference voltage circuit (2) also includes a second filter circuit, which includes a resistor R6 and a capacitor C2, for filtering the reference voltage to ensure its stability and accuracy.

5. The adjustable protection level circuit for a frequency converter according to claim 1, characterized in that: The voltage comparison circuit (3) includes a comparator circuit and an output circuit. The comparator circuit is used to compare the acquired voltage with the reference voltage and output a corresponding signal according to the comparison result. The output circuit processes the signal output by the comparator circuit and sends the processed signal to the interrupt port of the CPU to trigger the protection action.

6. The adjustable protection level circuit for a frequency converter according to claim 5, characterized in that: The comparator circuit includes a comparator chip IC1, and its specific connection method is as follows: Pin 1 of the comparator chip IC1 is the negative input terminal, which is connected to the output terminal of the voltage acquisition circuit (1); Pin 3 of comparator chip IC1 is the positive input terminal, which is connected to the output terminal of reference voltage circuit (2); Pin 2 of comparator chip IC1 is grounded; Pin 5 of comparator chip IC1 is connected to the power supply voltage and grounded through capacitor C3 to achieve power supply decoupling; Pin 4 of the comparator chip IC1 is the output terminal, which is connected to the output circuit.

7. The adjustable protection level circuit for a frequency converter according to claim 5, characterized in that: The output circuit includes resistors R4 and R5 and capacitor C4. One end of resistor R4 is connected to the output terminal of the comparator circuit, and the other end is connected to the power supply voltage. Resistor R5 and capacitor C4 are connected in series and grounded. This is used to filter the output signal of the comparator circuit and send the processed signal to the interrupt port of the CPU.

8. The adjustable protection level circuit for a frequency converter according to claim 5, characterized in that: The comparison voltage circuit (3) triggers the protection action based on the comparison result. The specific comparison process is as follows: When the acquired voltage is greater than the reference voltage, the output circuit sends a low-level signal to the CPU, triggering the CPU to execute protection actions, including stopping the inverter output, recording fault information, and issuing an alarm signal. When the acquired voltage is less than or equal to the reference voltage, the output circuit maintains a high-level signal, and the CPU does not perform any protection actions.

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