Charging resistor detection feedback circuit, variable frequency driver and air conditioner

Abstract

The invention discloses a charging resistance detection feedback circuit, a variable frequency driver and an air conditioner, and relates to the field of variable frequency control. Wherein the input end of the voltage detection module is connected with the charging resistor in parallel, the output end of the voltage detection module is connected with the input end of the feedback signal module, and the voltage detection module is used for converting the voltage on the charging resistor into a trigger signal. The output end of the feedback signal module is connected with a controller of the variable frequency driver. The feedback signal module is used for converting the trigger signal into a feedback signal representing the state of a contactor connected with the charging resistor in parallel. The charging resistor detection feedback circuit can feed back the working state of the contactor to the controller in time, so that when the charging resistor is serially connected into the main loop again due to the reset of the contactor contact caused by the contactor fault, corresponding measures can be taken in time to prevent the environment temperature of other devices from being influenced by the heating of the charging resistor; and the reliability of the variable-frequency driver is improved.

Description

Technical Field

[0001] The present application relates to the technical field of variable frequency control, and particularly relates to a charging resistor detection and feedback circuit, a variable frequency drive, and an air conditioner. Background Art

[0002] With the development of variable frequency drive technology, it has been gradually applied to various fields of industry, and the reliability requirements for variable frequency drives are also getting higher and higher.

[0003] Due to the existence of the DC bus capacitor in the variable frequency drive, the variable frequency drive cannot be directly powered on. Direct power-on will cause a large inrush current in the main circuit of the variable frequency drive due to the characteristic that the voltage across the bus capacitor cannot change suddenly. The excessive inrush current will damage the devices and rectifier bridge on the main circuit. Therefore, usually, industrial variable frequency drives will adopt the method of connecting a charging resistor in series on the main circuit to avoid the generation of inrush current. After the bus voltage rises, that is, after the bus capacitor has been charged, a contactor is used to bypass the charging resistor to avoid the charging resistor being connected in series in the main circuit for a long time. On the one hand, it will consume a part of the electric energy and reduce the efficiency of the variable frequency drive. On the other hand, it can prevent damage or even burnout caused by long-term heat accumulation.

[0004] However, when the contactor has problems such as insufficient coil suction, especially in scenarios where the variable frequency drive vibrates strongly, the contacts may intermittently or even fall off for a long time, resulting in the charging resistor being connected in series to the main circuit again. This will cause the charging resistor to heat up and affect the ambient temperature of other devices, and even overheat and burn, damaging the variable frequency drive. Summary of the Invention

[0005] In view of the above problems, the present application provides a charging resistor detection and feedback circuit, a variable frequency drive, and an air conditioner to achieve the purpose of improving the reliability of the variable frequency drive. The specific solutions are as follows:

[0006] The first aspect of the present application provides a charging resistor detection and feedback circuit, including: a voltage detection module and a feedback signal module;

[0007] The input end of the voltage detection module is connected in parallel with the charging resistor, the output end of the voltage detection module is connected to the input end of the feedback signal module, and the voltage detection module is used to convert the voltage on the charging resistor into a trigger signal;

[0008] The output end of the feedback signal module is connected to the controller of the variable frequency drive, and the feedback signal module is used to convert the trigger signal into a feedback signal representing the state of the contactor connected in parallel with the charging resistor.

[0009] In a possible implementation, the voltage detection module includes: a photoelectric conversion sub-module, two input ends of the photoelectric conversion sub-module are connected in parallel with a charging resistor, a first output end of the photoelectric conversion sub-module is connected to a power supply, and a second output end of the photoelectric conversion sub-module is connected to an input end of the feedback signal module.

[0010] In a possible implementation, the voltage detection module further includes: a full-bridge rectification sub-module, an input end of the full-bridge rectification sub-module is connected in parallel with the charging resistor, and an output end of the full-bridge rectification sub-module is correspondingly connected to two input ends of the photoelectric conversion sub-module.

[0011] In a possible implementation, a current-limiting sub-module is further connected in series to each input end of the photoelectric conversion sub-module.

[0012] In a possible implementation, the voltage detection module further includes: a voltage consumption sub-module connected between two input ends of the photoelectric conversion sub-module.

[0013] In a possible implementation, the voltage detection module further includes: a voltage stabilization sub-module, one end of the voltage stabilization sub-module is connected to the power supply, the other end of the voltage stabilization sub-module is grounded, and a connection midpoint of the voltage stabilization sub-module is connected to an input end of the feedback signal module.

[0014] In a possible implementation, the feedback signal module includes: a trigger sub-module, an input end of the trigger sub-module is connected to an output end of the voltage detection module, and an output end of the trigger sub-module is connected to the controller.

[0015] In a possible implementation, the feedback signal module further includes: a filtering sub-module, one end of the filtering sub-module is connected to an output end of the trigger sub-module, the other end of the filtering sub-module is grounded, and a connection midpoint of the filtering sub-module is connected to the controller.

[0016] The second aspect of the present application provides a variable frequency drive, including: a charging resistor detection and feedback circuit as described in the first aspect or any implementation manner of the first aspect above.

[0017] The third aspect of the present application provides an air conditioner, including: a variable frequency drive as described in the second aspect above.

[0018] With the above technical solution, the charging resistor detection and feedback circuit provided by the present application includes: a voltage detection module and a feedback signal module; wherein the input end of the voltage detection module is connected in parallel with the charging resistor, the output end of the voltage detection module is connected to the input end of the feedback signal module, and the voltage detection module is used to convert the voltage on the charging resistor into a trigger signal. The output end of the feedback signal module is connected to the controller of the variable frequency drive, and the feedback signal module is used to convert the trigger signal into a feedback signal representing the state of the contactor connected in parallel with the charging resistor. This charging resistor detection and feedback circuit can timely feedback the working state of the contactor to the controller. Furthermore, when the contactor fails and the contactor contacts reset, causing the charging resistor to be connected in series to the main circuit again, it can be detected in time and corresponding measures can be taken to avoid the charging resistor from generating heat and affecting the ambient temperature of other components, and even overheating and burning to damage the variable frequency drive, thereby improving the reliability of the variable frequency drive. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In combination with the accompanying drawings and with reference to the following specific embodiments, the above and other features, advantages, and aspects of the various embodiments of the present disclosure will become more apparent. Throughout the drawings, the same or similar reference numerals denote the same or similar elements. It should be understood that the drawings are schematic and the original components and elements are not necessarily drawn to scale.

[0020] Figure 1 It is a structural diagram of a charging resistor detection and feedback circuit provided by the present application;

[0021] Figure 2 It is a connection diagram of a charging resistor detection and feedback circuit provided by the present application in a variable frequency drive circuit;

[0022] Figure 3 It is another connection diagram of a charging resistor detection and feedback circuit provided by the present application in a variable frequency drive circuit;

[0023] Figure 4 It is a signal judgment level diagram of the contactor in the controller provided by the present application;

[0024] Figure 5 It is a connection diagram of the optoelectronic conversion sub-module in the charging resistor detection and feedback circuit provided by the present application;

[0025] Figure 6 It is a connection diagram of the full-bridge rectification sub-module in the charging resistor detection and feedback circuit provided by the present application;

[0026] Figure 7 It is a connection diagram of the current limiting sub-module in the charging resistor detection and feedback circuit provided by the present application;

[0027] Figure 8 It is a connection diagram of the voltage consumption sub-module in the charging resistor detection and feedback circuit provided by the present application;

[0028] Figure 9 Connection diagram of the voltage stabilizing sub-module provided by this application in the charging resistor detection feedback circuit;

[0029] Figure 10 Structural diagram in the feedback signal module provided by this application;

[0030] Figure 11 Schematic diagram of a charging resistor detection feedback circuit provided by this application. Detailed implementation manners

[0031] The following describes the embodiments of this application with reference to the accompanying drawings in the embodiments of this application. The terms used in the embodiments part of this application are only used to explain the specific embodiments of this application, rather than aiming to limit this application.

[0032] The following describes the embodiments of this application with reference to the accompanying drawings. Those of ordinary skill in the art will know that with the development of technology and the emergence of new scenarios, the technical solutions provided by the embodiments of this application are equally applicable to similar technical problems.

[0033] The terms "first", "second", etc. in the specification, claims and above-mentioned accompanying drawings of this application are used to distinguish similar objects, and do not have to be used to describe a specific order or sequence. It should be understood that such terms can be interchanged under appropriate circumstances, which is only a way of distinguishing when describing objects with the same attributes in the embodiments of this application. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, so that a process, method, system, product or device including a series of units does not have to be limited to those units, but may include other units not clearly listed or inherent to these processes, methods, products or devices.

[0034] With the development of frequency converter technology, it has gradually been applied to various fields of industry, and the reliability requirements for variable frequency drives are also getting higher and higher.

[0035] Where reference is made to Figure 2 and Figure 3As shown in the figure, due to the existence of the DC bus capacitor, the variable frequency drive cannot be directly powered on. Direct power-on will cause a large inrush current in the main circuit of the variable frequency drive because the voltage across the bus capacitor cannot change suddenly. The excessive inrush current will damage the devices and rectifier bridge in the main circuit. Therefore, industrial variable frequency drives usually adopt the method of connecting a charging resistor in series in the main circuit to avoid the generation of inrush current. After the bus voltage rises, that is, after the bus capacitor has been charged, the contactor is used to bypass the charging resistor to avoid the charging resistor being connected in series in the main circuit for a long time. On the one hand, it will consume a part of the electric energy and reduce the efficiency of the variable frequency drive. On the other hand, it can prevent damage or even burnout caused by the accumulation of heat over a long time.

[0036] Due to the simple structure and control method of the contactor, the reliability of the product is getting better and better. It only needs to ensure that the current driving the contactor coil is sufficient. Therefore, the current industrial variable frequency drive only designs the contact drive circuit of the contactor. However, the hidden danger of this design depends on the quality of the contactor. There may be insufficient suction force of the contactor coil, and in the scenario where the variable frequency drive vibrates strongly, the contacts may intermittently or even fall off for a long time, resulting in the charging resistor being connected in series in the main circuit again.

[0037] To solve the above problems, the embodiment of the present application provides a charging resistor detection and feedback circuit. The charging resistor detection and feedback circuit of the embodiment of the present application will be introduced in detail below with reference to the accompanying drawings.

[0038] Refer to Figure 1 , Figure 1 is the structural schematic diagram of a charging resistor detection and feedback circuit provided by the embodiment of the present application. As shown in Figure 1 , a charging resistor detection and feedback circuit provided by the embodiment of the present application may specifically include: a voltage detection module and a feedback signal module;

[0039] Among them, the input end of the voltage detection module is connected in parallel with the charging resistor, and the output end of the voltage detection module is connected to the input end of the feedback signal module. The voltage detection module is used to convert the voltage on the charging resistor into a trigger signal.

[0040] The output end of the feedback signal module is connected to the controller of the variable frequency drive. The feedback signal module is used to convert the trigger signal into a feedback signal representing the state of the contactor connected in parallel with the charging resistor.

[0041] Specifically, refer to Figures 2 to 4As shown, the contactor is connected in parallel with the charging resistor. When the variable frequency drive is powered on, the charging resistor needs to be connected in series to the main circuit to charge the capacitor on the bus. At this time, the contactor is in the off state, and there is a voltage drop across the charging resistor. When the capacitor charging is completed, the charging resistor needs to be bypassed. At this time, the contacts of the contactor are closed, so that there is no voltage drop across the charging resistor.

[0042] As shown in Figure 4 When the controller of the variable frequency drive starts charging, it can judge whether there is a fault in the contactor by detecting the level signal of the upper contact of the contactor. If the contactor is in the closed state after charging is completed, the contact should be a low-level signal, indicating that the contactor is closed normally and there is a voltage drop across the contact. When a continuous high-level signal or square wave signal is detected on the contact, it indicates that the contactor has an abnormal disconnection, resulting in the charging resistor being connected to the main circuit again.

[0043] Based on the above principle, by detecting whether there is a voltage drop across the charging resistor, it is possible to judge whether there is an abnormality in the contactor. As shown in Figure 2 and Figure 3 In actual use, the charging resistor detection feedback circuit can be connected in parallel with the charging resistor or in parallel with the contactor, which is not limited here.

[0044] The voltage detection module can generate a corresponding level trigger signal according to whether there is a voltage drop across the charging resistor and send it to the feedback signal module. The feedback signal module converts the trigger signal into a feedback signal that can represent the current state of the contactor. For example, when the capacitor is charging, there is a voltage drop across the charging resistor, and the voltage detection module will generate a high-level trigger signal. Accordingly, the feedback signal module generates a high-level signal indicating that the current contactor is in the off state according to this high-level signal. When the charging is completed, the voltage detection module will generate a low-level trigger signal. Accordingly, the feedback signal module generates a low-level signal indicating that the current contactor is in the closed state according to this low-level signal. That is, the low-level signal output by the feedback signal module represents that the contactor is in the closed state, and the high-level signal represents that the contactor is in the off state. Then, after the capacitor charging is completed and the variable frequency drive is working normally, the controller should receive all low-level signals. If there is a continuous high-level or square wave signal, it means that there is a fault in the contactor, resulting in the charging resistor being connected to the circuit again. The controller needs to feedback a fault signal and can control the frequency converter to stop and wait for processing.

[0045] As can be seen above, the charging resistor detection and feedback circuit, through the above voltage detection module and feedback signal module, can determine whether the charging resistor is bypassed by detecting the voltage across the charging resistor when the charging is completed and the bypass contactor drive signal has been issued. At the same time, during the operation of the frequency converter, it can detect that due to contactor failure, the contactor contacts reset, resulting in the charging resistor being connected in series to the main circuit again, which may cause the charging resistor to heat up and affect the ambient temperature of other components, and even overheat and burn, damaging the frequency converter drive. By judging the feedback signal, this problem can be avoided, and the reliability of industrial frequency conversion drive can be improved at a relatively low cost.

[0046] In a possible implementation, referring to Figure 5 The voltage detection module shown includes: a photoelectric conversion sub-module. The two input terminals of the photoelectric conversion sub-module are connected in parallel with the charging resistor. The first output terminal of the photoelectric conversion sub-module is connected to the power supply, and the second output terminal of the photoelectric conversion sub-module is connected to the input terminal of the feedback signal module.

[0047] Specifically, referring to Figure 11 As shown, the photoelectric conversion sub-module can be a photocoupler, namely U1. The voltage signal across the charging resistor between Relay_CON1 and Relay_CON2 is converted into a corresponding trigger signal by the photocoupler U1 and then connected to the signal feedback module. Correspondingly, referring to Figure 10 As shown, the signal feedback module may include a trigger sub-module. The input terminal of the trigger sub-module is connected to the output terminal of the voltage detection module, and the output terminal of the trigger sub-module is connected to the controller. Here, referring to Figure 11 The trigger sub-module U2 shown can be composed of a trigger with the function of generating a trigger signal. Here, a Schmitt trigger is used, which has better anti-interference and filtering capabilities while being able to respond to the trigger signal, so as to enhance the stability of the circuit and ensure the accuracy and reliability of the feedback signal.

[0048] It can be understood that those skilled in the art can also use other devices with the same functions to replace the above U1 and U2, which will not be limited here.

[0049] To further improve the stability and safety of the circuit and ensure the normal operation of each component. Referring to Figure 6 and Figure 7 As shown, the voltage detection module further includes: a full-bridge rectification sub-module. The input terminal of the full-bridge rectification sub-module is connected in parallel with the charging resistor, and the output terminal of the full-bridge rectification sub-module is correspondingly connected to the two input terminals of the photoelectric conversion sub-module. A current-limiting sub-module is connected in series to each input terminal of the photoelectric conversion sub-module.

[0050] Specifically, it can be referred to Figure 11As shown, during actual use, to ensure the normal operation of optocoupler U1, it is necessary to limit the connection order of the Relay_CON1 and Relay_CON2 signal lines to the primary side of optocoupler U1 to avoid damage to the optocoupler caused by the reverse connection of the two signal lines. To avoid damage to the optocoupler caused by the reverse connection of the signal lines, a full-bridge rectifier sub-module is added. The full-bridge rectifier sub-module consists of 4 diodes, with 2 in series as a group and then in parallel.

[0051] Among them, the first diode D1 and the second diode D2 are in series as a group, and the third diode D3 and the fourth diode D4 are in series as a group. The Relay_CON1 signal line is connected to the connection point of the first diode D1 and the second diode D2, and the Relay_CON2 signal line is connected to the connection point of the third diode D3 and the fourth diode D4.

[0052] Resistors R1 and R2 form a current-limiting sub-module, and resistors R3 and R4 form another current-limiting sub-module. It can be seen that regardless of how the Relay_CON1 and Relay_CON2 signal lines are connected in parallel to the charging resistor, after being restricted by the full-bridge rectifier sub-module composed of diodes, they can only be input along the positive direction of the light-emitting diode in optocoupler U1, thus avoiding damage to the optocoupler and providing convenience for the use of the circuit.

[0053] To further ensure the normal and stable operation of optocoupler U1, referring to Figure 8 Figure 9 The voltage detection module further includes: a voltage consumption sub-module connected between the two input ends of the optoelectronic conversion sub-module.

[0054] Specifically, referring to Figure 11 As described, the voltage consumption sub-module is resistor R5, which can consume the voltage in the light-emitting diode of optocoupler U1 after power-off to avoid the influence of residual voltage on the next signal acquisition and ensure the accuracy of the detection result.

[0055] In a possible implementation, to further improve the reliability of the detection result, referring to Figure 9 and Figure 10 The voltage detection module further includes: a voltage stabilization sub-module. One end of the voltage stabilization sub-module is connected to the power supply, the other end is grounded, and the connection midpoint of the voltage stabilization sub-module is connected to the input end of the feedback signal module.

[0056] Specifically, referring to Figure 11 As shown, the voltage stabilization sub-module consists of capacitor C1 and resistor R6. When the charging is completed, the controller issues a contactor drive signal to make the contactor contacts close, thereby bypassing the charging resistor. At this time, the voltage across the charging resistor is close to 0. Therefore, there is no drive signal on the primary side of optocoupler U1, and there is no output signal on the secondary side. The trigger signal is pulled down to a low level due to the existence of the R6 pull-down resistor.

[0057] Further, referring to Figure 10 as shown, the feedback signal module further includes: a filtering sub-module, one end of the filtering sub-module is connected to the output end of the trigger sub-module, the other end of the filtering sub-module is grounded, and the connection midpoint of the filtering sub-module is connected to the controller.

[0058] Specifically, referring to Figure 11 as shown, the resistor R7 and the capacitor C2 constitute the filtering sub-module, which filters the signal DSP_Rel input to the controller, and further ensures the accuracy of the controller detection result.

[0059] Based on the same design concept, the present application also provides a variable frequency drive, including: the charging resistor detection feedback circuit as described in the above embodiment.

[0060] The embodiment of the present application also provides an air conditioner, including: the variable frequency drive as described in the above embodiment.

[0061] In addition, it should be noted that the device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place, or may be distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. In addition, in the attached drawings of the device embodiments provided by the present application, the connection relationship between the modules indicates that they have a communication connection, which can be specifically implemented as one or more communication buses or signal lines.

[0062] Through the description of the above embodiments, those skilled in the art can clearly understand that the present application can be implemented by means of software plus necessary general hardware, and of course, it can also be implemented by dedicated hardware including dedicated integrated circuits, dedicated CPUs, dedicated memories, dedicated components, etc. Generally, functions completed by computer programs can be easily implemented by corresponding hardware, and the specific hardware structures for implementing the same function can also be various, such as analog circuits, digital circuits or dedicated circuits. However, for the present application, in more cases, software program implementation is a better implementation method. Based on such an understanding, the technical solution of the present application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. The computer software product is stored in a readable storage medium, such as a floppy disk, USB flash drive, mobile hard disk, ROM, RAM, magnetic disk or optical disc of a computer, etc., and includes several instructions for causing a computer device (which can be a personal computer, training device, or network device, etc.) to execute the methods described in various embodiments of the present application.

[0063] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product.

[0064] The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the processes or functions described in the embodiments of the present application are generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, training device, or data center to another website, computer, training device, or data center via wired (such as coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (such as infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can store or a data storage device such as a training device or data center that includes one or more integrated available media. The available medium can be a magnetic medium (such as a floppy disk, hard disk, magnetic tape), an optical medium (such as a DVD), or a semiconductor medium (such as a solid state disk (SSD)), etc.

Claims

1. A charging resistance detection and feedback circuit, characterized in that, Comprising: A voltage detection module and a feedback signal module; The input end of the voltage detection module is connected in parallel with the charging resistor, the output end of the voltage detection module is connected to the input end of the feedback signal module, and the voltage detection module is used to convert the voltage on the charging resistor into a trigger signal; The output end of the feedback signal module is connected to the controller of the variable frequency drive, and the feedback signal module is used to convert the trigger signal into a feedback signal characterizing the state of the contactor connected in parallel with the charging resistor.

2. The charging resistor detection feedback circuit according to claim 1, wherein The voltage detection module includes: a photoelectric conversion sub-module, the two input ends of the photoelectric conversion sub-module are connected in parallel with the charging resistor, the first output end of the photoelectric conversion sub-module is connected to the power supply, and the second output end of the photoelectric conversion sub-module is connected to the input end of the feedback signal module.

3. The charging resistance detection and feedback circuit according to claim 2, wherein The voltage detection module further includes: a full-bridge rectification sub-module, the input end of the full-bridge rectification sub-module is connected in parallel with the charging resistor, and the output end of the full-bridge rectification sub-module is correspondingly connected to the two input ends of the photoelectric conversion sub-module.

4. The charging resistor detection and feedback circuit according to claim 2, wherein, A current limiting sub-module is further connected in series to each input end of the photoelectric conversion sub-module.

5. The charging resistance detection feedback circuit according to claim 2, wherein The voltage detection module further includes: a voltage consumption sub-module connected between the two input ends of the photoelectric conversion sub-module.

6. The charging resistance detection feedback circuit according to claim 2, wherein The voltage detection module further includes: a voltage stabilizing sub-module, one end of the voltage stabilizing sub-module is connected to the power supply, the other end of the voltage stabilizing sub-module is grounded, and the connection midpoint of the voltage stabilizing sub-module is connected to the input end of the feedback signal module.

7. The charging resistance detection and feedback circuit according to claim 1, characterized in that The feedback signal module includes: a trigger sub-module, the input end of the trigger sub-module is connected to the output end of the voltage detection module, and the output end of the trigger sub-module is connected to the controller.

8. The charging resistance detection feedback circuit according to claim 7, wherein, The feedback signal module further includes: a filtering sub-module, one end of the filtering sub-module is connected to the output end of the trigger sub-module, the other end of the filtering sub-module is grounded, and the connection midpoint of the filtering sub-module is connected to the controller.

9. A variable frequency drive, characterized in that, Comprising: The charging resistor detection and feedback circuit according to any one of claims 1 to 8.

10. An air conditioner, characterized in that, Comprising: The variable frequency drive according to claim 9.

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