Direct current bus charging resistor overload protection circuit and direct current charging circuit

Abstract

The embodiment of the utility model relates to a DC bus charging resistor overload protection circuit and a DC charging circuit. The DC bus charging resistor overload protection circuit comprises a charging resistor, a bus switch module and a switch control module, the charging resistor is arranged on the direct current bus; the output end of the switch control module is connected with the control end of the bus switch module, and at least two input ends of the switch control module are used for receiving at least two state signals; a switch contact of the bus switch module is connected in parallel with the charging resistor. According to the embodiment of the invention, the bus switch module can be disconnected and connected with the charging resistor only when multiple conditions are met, so that the charging resistor is prevented from being connected with the direct-current bus due to an abnormal condition, and the charging resistor is prevented from being overloaded or even damaged, thereby improving the safety and stability of the circuit.

Description

Technical Field

[0001] This application relates to the field of motor drive technology, and in particular to a DC bus charging resistor overload protection circuit and a DC charging circuit. Background Technology

[0002] In equipment such as air conditioning units, DC charging circuits are needed to drive the motors of compressors and other devices. In a DC charging circuit, a charging loop is typically set up on the DC bus to charge the capacitors in the drive circuit according to a set charging time. The charging logic is as follows: upon power-up, the main circuit is charged through a cement resistor. When the bus voltage is detected to be greater than a preset voltage value, a large relay connected in parallel with the cement resistor is activated to short-circuit the cement resistor and reduce energy loss. However, due to abnormalities in debugging control or logic control, the motor may stop, which will then cause the large relay to disconnect in the program. At this time, other modules may still be running; for example, in an air conditioning unit, the fan's IPM module (Intelligent Power Module) may still be working, forming a current loop. This can overload the cement resistor in the charging loop, causing it to damage and preventing the DC charging circuit from operating normally. Utility Model Content

[0003] In view of this, in order to solve some or all of the above-mentioned technical problems, this application provides a DC bus charging resistor overload protection circuit, a display panel, and a display device.

[0004] In a first aspect, embodiments of this application provide a DC bus charging resistor overload protection circuit and a DC charging circuit. The circuit includes: a charging resistor, a bus switch module, and a switch control module; the charging resistor is disposed on the DC bus; the output terminal of the switch control module is connected to the control terminal of the bus switch module, and at least two input terminals of the switch control module are used to receive at least two state signals; the switch contacts of the bus switch module are connected in parallel with the charging resistor.

[0005] In one possible implementation, the switch control module includes logic gate units and transistors; at least two input terminals of the logic gate units are used to receive at least two state signals respectively, and the output terminal of the logic gate units is connected to the control terminal of the transistors; the output terminal of the transistors is connected to the control terminal of the bus switch module.

[0006] In one possible implementation, the logic gate unit includes an OR gate, the transistor includes a first transistor, at least two input terminals of the OR gate are respectively used to receive at least two state signals, the output terminal of the OR gate is connected to the control terminal of the first transistor, and the output terminal of the first transistor is connected to the control terminal of the bus switch module.

[0007] In one possible implementation, the logic gate unit includes a NOR gate, the transistor includes a second transistor, at least two input terminals of the NOR gate are respectively used to receive at least two state signals, the output terminal of the NOR gate is connected to the control terminal of the second transistor, and the output terminal of the second transistor is connected to the control terminal of the bus switch module.

[0008] In one possible implementation, the bus switch module includes a normally open relay, the control terminal of which is connected to the output terminal of the switch control module, and the switch contacts of the relay are connected in parallel with a charging resistor.

[0009] In one possible implementation, the bus switch module also includes a diode connected in reverse parallel with the control terminal of the relay.

[0010] Secondly, embodiments of this application provide a DC charging circuit, which includes: the aforementioned DC bus charging resistor overload protection circuit, a controller, and at least two status detection modules; each of the at least two status detection modules is connected to a corresponding target sampling point in the DC charging circuit; at least two signal acquisition terminals of the controller are connected to at least two status detection modules; and at least two status signal output terminals of the controller are connected to the input terminals of the switch control module in the DC bus charging resistor overload protection circuit.

[0011] In one possible implementation, at least two status detection modules include a charging status detection module and a fan control module; the charging status detection module is connected to the DC bus of the DC charging circuit; and the fan control module is connected in parallel with the charging capacitor of the DC charging circuit.

[0012] Thirdly, embodiments of this application provide a frequency converter, including: a rectifier section, an inverter section, and a DC charging circuit as described above, wherein the DC charging circuit is disposed between the rectifier section and the inverter section.

[0013] Fourthly, this application provides an air conditioning device, including: the above-mentioned frequency converter and compressor, wherein the three-phase power input terminal of the compressor is connected to the three-phase output terminal of the frequency converter.

[0014] The DC bus charging resistor overload protection circuit and DC charging circuit provided in this application embodiment, by setting a switch control module and a bus switch module, allows the switch control module to receive at least two state signals at at least two input terminals. Based on these signals, the switch control module controls the on / off state of the bus switch module accordingly. In other words, the switch control module can only control the bus switch module to disconnect when multiple conditions are met. Compared to the conventional method of controlling the large relay to disconnect and connect the charging resistor when the motor stops, this embodiment requires multiple conditions to be met before the bus switch module can disconnect and the charging resistor can be connected. This avoids abnormal situations where the charging resistor is connected to the DC bus, causing overload or even damage to the charging resistor, thereby improving the safety and stability of the circuit. Attached Figure Description

[0015] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0016] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0018] Figure 1 A schematic diagram of a DC bus charging resistor overload protection circuit provided in this application embodiment;

[0019] Figure 2 A schematic diagram of another DC bus charging resistor overload protection circuit provided in this application embodiment;

[0020] Figure 3 A schematic diagram of another DC bus charging resistor overload protection circuit provided in this application embodiment;

[0021] Figure 4 A schematic diagram of another DC bus charging resistor overload protection circuit provided in this application embodiment;

[0022] Figure 5 A schematic diagram of another DC bus charging resistor overload protection circuit provided in this application embodiment;

[0023] Figure 6 This is a schematic diagram of a DC charging circuit provided in an embodiment of this application;

[0024] Figure 7 This is a schematic diagram of another DC charging circuit provided in an embodiment of this application;

[0025] Figure 8 This is a schematic diagram of the structure of a frequency converter provided in an embodiment of this application;

[0026] Figure 9 This is a schematic diagram of the structure of an air conditioning device provided in an embodiment of this application.

[0027] Figure label:

[0028] 100 - DC bus charging resistor overload protection circuit; 101 - Bus switch module; 102 - Switch control module; 600 - DC charging circuit; 601 - Controller; 602 - At least two status detection modules; 6021 - Charging status detection module; 6022 - Fan control module; 800 - Inverter; 801 - Rectifier section; 802 - Inverter section; 900 - Air conditioning equipment; 901 - Compressor. Detailed Implementation

[0029] Various exemplary embodiments of this application will now be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of this application.

[0030] Those skilled in the art will understand that the terms "first" and "second" in the embodiments of this application are only used to distinguish different steps, devices or modules, and do not represent any specific technical meaning, nor do they indicate the logical order between them.

[0031] It should also be understood that in this embodiment, "multiple" can refer to two or more, and "at least one" can refer to one, two or more.

[0032] It should also be understood that any component, data or structure mentioned in the embodiments of this application can generally be understood as one or more unless explicitly defined or given contrary guidance in the context.

[0033] Furthermore, the term "and / or" in this application is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this application generally indicates that the preceding and following related objects have an "or" relationship.

[0034] It should also be understood that the description of the various embodiments in this application emphasizes the differences between the various embodiments, and the similarities or similarities can be referred to each other. For the sake of brevity, they will not be described in detail.

[0035] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the scope of this application and its application or use.

[0036] Techniques, circuits, and devices known to a person skilled in the art may not be discussed in detail, but where appropriate, such techniques, circuits, and devices should be considered part of the specification.

[0037] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0038] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. To facilitate understanding of the embodiments of this application, the application will be described in detail below with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0039] Figure 1 This is a schematic diagram of a DC bus charging resistor overload protection circuit 100 provided in an embodiment of this application. The circuit 100 is typically used in frequency converters and specifically includes: a charging resistor R1, a bus switch module 101, and a switch control module 102.

[0040] like Figure 1 As shown, the charging resistor is placed on the DC bus. This charging resistor is typically a cement resistor capable of withstanding high current. To clearly describe the function of this circuit, Figure 1 The circuit structure of a portion of the DC power supply where the DC bus is located is also shown, including inductor L1, capacitors C1 and C2, and resistors R2 and R3.

[0041] The output terminal of the switch control module 102 is connected to the control terminal of the bus switch module 101, and at least two input terminals of the switch control module 102 are used to receive at least two types of status signals. The switch contacts of the bus switch module 101 are connected in parallel with the charging resistor.

[0042] The switch control module 102 can be of various types, such as an MCU (Microcontroller Unit) or a gate circuit. The bus switch module 101 is a device with controlled switching function, such as a relay or a thyristor.

[0043] The switch control module 102 can receive at least two status signals and, when the at least two status signals meet certain conditions, output a corresponding control signal to the bus switch module 101. The types of the aforementioned at least two status signals can be various. For example, the at least two status signals may include: a bus charging status signal, a fan operating status signal, etc. Furthermore, the at least two status signals may also include other types of signals, such as an over-temperature warning signal, a foreign object intrusion warning signal, etc.

[0044] In a conventional DC bus, a charging resistor is connected in parallel with a relay. If the voltage on the DC bus does not reach a threshold voltage, the relay opens, charging the capacitor on the DC bus. When the voltage on the DC bus reaches the threshold voltage, the relay closes, short-circuiting the charging capacitor, and the DC bus outputs DC power normally. This embodiment only controls the bus switch module 101 to open when at least two status signals indicate that the circuit is not operating normally. As long as one status signal indicates that a component is still operating normally, the bus switch module 101 is closed, short-circuiting the charging resistor to prevent excessive current from flowing through it.

[0045] In one application scenario, at least two status signals are included: a bus charging status signal and a fan operating status signal. Specifically, the bus charging status signal indicates that the capacitor on the DC bus has not finished charging (i.e., the voltage on the DC bus has not reached the voltage threshold), and the fan operating status signal indicates that the fan is not running. In this case, the bus switch module 101 is opened, and the charging resistor is connected to the DC bus to charge the capacitor. Once the capacitor charging is complete or the motor is running, the bus switch module 101 is closed, short-circuiting the charging resistor to prevent a large current from flowing through it.

[0046] The DC bus charging resistor overload protection circuit provided in this application embodiment, by setting up a switch control module and a bus switch module, allows the switch control module to receive at least two types of status signals at its at least two input terminals. Based on these signals, the switch control module controls the on / off state of the bus switch module accordingly. In other words, the switch control module can only disconnect the bus switch module when multiple conditions are met. Compared to the conventional method of disconnecting the large relay and connecting the charging resistor when the motor stops, this embodiment requires multiple conditions to be met before disconnecting the bus switch module and connecting the charging resistor. This avoids abnormal situations where the charging resistor is connected to the DC bus, causing overload or even damage to the charging resistor, thereby improving the safety and stability of the circuit.

[0047] In some optional implementations of this embodiment, such as Figure 2 As shown, the switch control module 102 includes a logic gate unit 1011 and a transistor 1012.

[0048] At least two inputs of logic gate unit 1011 are used to receive at least two state signals, and the output of logic gate unit 1011 is connected to the control terminal of transistor 1012. The output of transistor 1012 is connected to the control terminal of bus switch module 101.

[0049] The logic gate unit 1011 can include various types, such as OR gates and NOR gates. The transistor 1012 is used to drive the bus switch module 101, and the type of transistor 1012 matches the type of the logic gate unit 1011. Typically, the combination of the logic gate unit 1011 and transistor 1012 must conform to the following rules: when at least two state signals indicate that the circuit is not operating normally, a disconnect command is output to the bus switch module 101, connecting the charging resistor. If at least one state signal indicates that a component is still operating normally, a close command is output to the bus switch module 101, short-circuiting the charging resistor.

[0050] This embodiment, by setting logic gate units and transistors, enables the control of the charging resistor's connection state based on at least two state signals using a simple circuit, thereby helping to reduce circuit costs and the complexity of the control program.

[0051] In some optional implementations of this embodiment, such as Figure 3 As shown, the logic gate unit 1011 includes an OR gate U1, the transistor 1012 includes a first transistor T1, at least two input terminals of the OR gate are used to receive at least two state signals respectively, the output terminal of the OR gate is connected to the control terminal of the first transistor T1, and the output terminal of the first transistor T1 is connected to the control terminal of the bus switch module 101.

[0052] When the control terminal of the first transistor T1 receives a high level, it can output a closing command. The closing command is used to control the bus switch module 101 to close, shorting the charging resistor.

[0053] Figure 3 In the circuit shown, the first transistor T1 can be an NPN transistor, with its base connected to the output of the OR gate, its collector connected to a 12V power supply, and its emitter connected to the control terminal of the bus switch module 101. The OR gate has two inputs, receiving two status signals (e.g., bus charging status signal S1 and fan operating status signal S2). When both S1 and S2 are 0 (low level), i.e., the bus voltage has not reached the threshold and the fan is not running, the OR gate outputs a low level, the transistor is cut off, the bus switch module 101 is open, and the charging resistor is connected to the DC bus, enabling power supply. When at least one of S1 and S2 is 1 (high level), i.e., the bus voltage has reached the threshold and / or the fan is running, the OR gate outputs a high level, the transistor is turned on, the bus switch module 101 is closed, and the charging resistor is short-circuited to prevent overload.

[0054] Optionally, the first transistor T1 described above can also be other types of transistors, such as an N-type field-effect transistor. Furthermore, Figure 3 In the circuit shown, the closing command output by the first transistor T1 is a high-level signal. The bus switch module 101 closes when it receives a high-level signal and opens when it receives a low-level signal. Optionally, the closing command of the first transistor T1 can also be a low-level signal (e.g., Figure 3 The emitter of T1 is grounded, and the collector is connected to a 12V power supply through a pull-up resistor. The collector is also connected to the control terminal of the bus switch module 101. The type of the bus switch module 101 is adjusted so that it closes when it receives a low-level signal and opens when it receives a high-level signal.

[0055] This embodiment sets the logic gate unit as an OR gate, and the conduction and cutoff states of the first transistor correspond to the OR gate, thereby realizing the control of the state of the bus switch module using a simple logic control circuit, which helps to reduce the difficulty and cost of circuit implementation.

[0056] In some optional implementations of this embodiment, such as Figure 4 As shown, the logic gate unit 1011 includes a NOR gate U2, the transistor 1012 includes a second transistor T2, at least two input terminals of the NOR gate U2 are respectively used to receive at least two state signals, the output terminal of the NOR gate U2 is connected to the control terminal of the second transistor T2, and the output terminal of the second transistor T2 is connected to the control terminal of the bus switch module 101.

[0057] When the control terminal of the second transistor T2 receives a low level, it can output a closing command. The closing command is used to control the bus switch module 101 to close, shorting the charging resistor.

[0058] Figure 4 In the circuit shown, the second transistor T2 can be a PNP transistor. Its base is connected to the output of the NOR gate, its emitter is connected to the 12V power supply, and its collector is connected to the control terminal of the bus switch module 101. The NOR gate has two input terminals, receiving two status signals (such as S1 and S2 mentioned above). When both S1 and S2 are 0 (low level), i.e., the bus voltage has not reached the threshold and the fan is not running, the NOR gate outputs a high level, the transistor is cut off, the bus switch module 101 is open, and the charging resistor is connected to the DC bus, enabling power supply. When at least one of S1 and S2 is 1 (high level), i.e., the bus voltage has reached the threshold and / or the fan is running, the NOR gate outputs a low level, the transistor is turned on, the bus switch module 101 is closed, and the charging resistor is short-circuited to prevent overload of the charging resistor.

[0059] Optionally, the second transistor T2 described above can also be other types of transistors, such as a P-type field-effect transistor. Furthermore, Figure 4 In the circuit shown, the closing command output by the second transistor T2 is a low-level signal. The bus switch module 101 closes when it receives a low-level signal and opens when it receives a high-level signal. Optionally, the closing command of the second transistor T2 can also be a high-level signal (e.g., Figure 4 The collector of T2 is grounded, the emitter is connected to a 12V power supply through a pull-up resistor, and the emitter is connected to the control terminal of the bus switch module 101. The type of the bus switch module 101 is adjusted to close when a high-level signal is received and open when a low-level signal is received.

[0060] This embodiment further enriches the ways to control the bus switch module and improves the flexibility of circuit implementation by setting the logic gate unit as a NOR gate and the conduction and cutoff states of the second transistor corresponding to the NOR gate.

[0061] In some optional implementations of this embodiment, the bus switch module 101 includes a normally open relay K1, the control terminal of the relay K1 is connected to the output terminal of the switch control module 102, and the switch contacts of the relay K1 are connected in parallel with the charging resistor.

[0062] like Figure 5 As shown, the relay K1 in this embodiment is connected with... Figure 3The corresponding embodiment is described below. The electromagnetic coil inside relay K1 has two control terminals, one grounded and the other connected to the output terminal of T1 included in the switch control module 102. The two switch contacts of relay K1 are connected in parallel with a charging resistor. When both S1 and S2 are 0, T1 outputs a low level, no current flows through the control terminal of relay K1, and the two switch contacts are disconnected. When S1 and / or S2 are 1, T1 outputs a high level, current flows through the control terminal of relay K1, and the two switch contacts are connected.

[0063] This embodiment achieves control of the charging status of the DC bus through multiple status signals by setting a normally open relay. This structure is simple, effective, and inexpensive.

[0064] In some optional implementations of this embodiment, such as Figure 5 As shown, the bus switch module 101 also includes a diode D1, which is connected in reverse parallel with the control terminal of the relay K1. That is, the cathode of the diode is connected to the output terminal of the switch control module 102, and the anode is grounded.

[0065] At the moment the coil of relay K1 is de-energized, a large reverse current will be generated. The reverse current can be released through diode D1, clamping the voltage at the forward conduction voltage of diode D1, thereby protecting the switch control module 102. In addition, diode D1 will prolong the coil's operating time and reduce the impact of large current on the components.

[0066] Figure 6 This is a schematic diagram of a DC charging circuit 600 provided in an embodiment of this application. This circuit 600 is typically used in frequency converters. Figure 6 As shown, the DC charging circuit specifically includes: the DC bus charging resistor overload protection circuit 100 described in the above embodiments, and a controller 601 and at least two status detection modules 602 (including status detection module - status detection module N).

[0067] Each of the at least two state detection modules is connected to the corresponding target sampling point in the DC charging circuit.

[0068] The at least two status detection modules may include various modules for real-time monitoring of the DC charging circuit. As an example, the at least two status detection modules may include a charging status detection module and a fan control module. Optionally, a temperature detection module, etc., may also be included.

[0069] At least two signal acquisition terminals of controller 601 are respectively connected to at least two status detection modules. At least two status signal output terminals of controller 601 are connected to the input terminals of switch control module 102 in DC bus charging resistor overload protection circuit.

[0070] The switch control module 102 can receive at least two status signals output from at least two status signal output terminals. The switch control module 102 controls the connection status of the charging resistor on the DC bus according to the control method described in the DC bus charging resistor overload protection circuit.

[0071] The DC charging circuit provided in this application embodiment, by applying the above-mentioned DC bus charging resistor overload protection circuit and setting at least two status detection modules, enables the controller to control the on / off state of the bus switch module by using at least two collected status signals, thereby preventing abnormal situations from causing the charging resistor to be connected to the DC bus, causing the charging resistor to overload or even be damaged, thus improving the safety and stability of the DC charging circuit operation.

[0072] In some optional implementations of this embodiment, such as Figure 7 As shown, at least two status detection modules include a charging status detection module 6021 and a fan control module 6022.

[0073] The charging status detection module 6021 is connected to the DC bus of the DC charging circuit; the fan control module 6022 is connected in parallel with the charging capacitor (C2) of the DC charging circuit.

[0074] The aforementioned charging status detection module 6021 can be used to detect the voltage on the DC bus. If the voltage reaches a preset voltage threshold, the controller can output a bus charging status signal indicating that charging is complete. The fan control module 6022 can be an IPM module. The controller can use the fan control module 6022 to detect whether the fan is running in real time, and then output a fan status signal indicating whether the fan is running to the switch control module 102.

[0075] As an example, this embodiment can be compared with the above. Figure 3 The corresponding embodiments are combined. An OR gate receives the bus charging status signal S1 and the fan operating status signal S2 sent by the controller. When both S1 and S2 are 0 (low level), i.e., the bus voltage has not reached the threshold and the fan is not running, the OR gate outputs a low level, the transistor is cut off, the bus switch module 101 is open, and the charging resistor is connected to the DC bus, enabling power supply. When at least one of S1 and S2 is 1 (high level), i.e., the bus voltage has reached the threshold and / or the fan is running, the OR gate outputs a high level, the transistor is turned on, the bus switch module 101 is closed, and the charging resistor is short-circuited to prevent overload.

[0076] This embodiment, by setting up a charging status detection module and a fan control module, collects multiple signals from the DC charging circuit and jointly controls the on / off state of the relay. Compared to the conventional method of disconnecting the large relay and connecting the charging resistor when the motor stops, this embodiment requires the bus switch module to disconnect and connect the charging resistor only when charging is not complete and the motor is not running. This avoids situations where the charging resistor is connected to the DC bus while the fan is still running, potentially causing overload or even damage to the charging resistor, thus improving the safety and stability of the circuit.

[0077] Figure 8 A schematic diagram of the structure of a frequency converter 800 provided in an embodiment of this application is shown below. Figure 8 As shown, the inverter 800 includes: a rectifier section 801, an inverter section 802, and the aforementioned DC charging circuit 600, which is disposed between the rectifier section and the inverter section.

[0078] The aforementioned rectifier section is used to rectify the input AC power to obtain DC power, which is then transmitted to the DC charging circuit via the DC bus. The DC power output from the DC charging circuit is converted into three-phase AC power by the inverter and then output to the driven motor through the three-phase AC power output terminals (U, V, W). Figure 8 L2, L3, and L4 in the text refer to the coils included in the motor.

[0079] The inverter provided in this application embodiment, by applying the above-mentioned DC charging circuit, realizes the control of the connection state of the charging resistor by using at least two collected state signals, avoiding abnormal situations that cause the charging resistor to be connected to the DC bus, causing the charging resistor to overload or even be damaged, thereby improving the safety and stability of the inverter operation.

[0080] Figure 9 This is a structural schematic diagram of an air conditioning device 900 provided in an embodiment of this application, as shown below. Figure 9 As shown, the air conditioning equipment 900 includes: the aforementioned frequency converter 800 and compressor 901, with the three-phase power input terminal of the compressor connected to the three-phase output terminal of the frequency converter.

[0081] The air conditioning equipment provided in this application embodiment, by applying the above-mentioned frequency converter, realizes the control of the connection state of the charging resistor by using at least two collected state signals, avoiding abnormal situations that cause the charging resistor to be connected to the DC bus, causing the charging resistor to overload or even be damaged, thereby improving the safety and stability of the air conditioning equipment operation.

[0082] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different circuits to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0083] The steps of the circuits or algorithms described in connection with the embodiments disclosed herein can be implemented in hardware, in a software module executed by a processor, or in a combination of both. The software module can be located in random access memory (RAM), main memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art.

[0084] It should be understood that the terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “described” as used herein may also mean including the plural forms. The terms “comprising,” “including,” “containing,” and “having” are inclusive and therefore indicate the presence of the stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The steps, processes, and operations described herein are not construed as requiring them to be performed in a particular order described or illustrated unless the order of performance is explicitly indicated. It should also be understood that additional or alternative steps may be used.

[0085] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A DC bus charging resistor overload protection circuit, characterized in that, The circuit includes: a charging resistor, a bus switch module, and a switch control module; The charging resistor is located on the DC bus; The output terminal of the switch control module is connected to the control terminal of the bus switch module, and at least two input terminals of the switch control module are used to receive at least two types of status signals. The switch contacts of the bus switch module are connected in parallel with the charging resistor.

2. The circuit according to claim 1, characterized in that, The switch control module includes logic gate units and transistors; The logic gate unit has at least two input terminals for receiving at least two state signals, and the output terminal of the logic gate unit is connected to the control terminal of the transistor. The output terminal of the transistor is connected to the control terminal of the bus switch module.

3. The circuit according to claim 2, characterized in that, The logic gate unit includes an OR gate, the transistor includes a first transistor, at least two input terminals of the OR gate are respectively used to receive the at least two state signals, the output terminal of the OR gate is connected to the control terminal of the first transistor, and the output terminal of the first transistor is connected to the control terminal of the bus switch module.

4. The circuit according to claim 2, characterized in that, The logic gate unit includes a NOR gate, the transistor includes a second transistor, at least two input terminals of the NOR gate are respectively used to receive the at least two state signals, the output terminal of the NOR gate is connected to the control terminal of the second transistor, and the output terminal of the second transistor is connected to the control terminal of the bus switch module.

5. The circuit according to claim 1, characterized in that, The bus switch module includes a normally open relay, the control terminal of which is connected to the output terminal of the switch control module, and the switch contacts of which are connected in parallel with the charging resistor.

6. The circuit according to claim 5, characterized in that, The bus switch module also includes a diode, which is connected in reverse parallel with the control terminal of the relay.

7. A DC charging circuit, characterized in that, The circuit includes the DC bus charging resistor overload protection circuit according to any one of claims 1-6, as well as a controller and at least two status detection modules; Each of the at least two state detection modules is connected to the corresponding target sampling point in the DC charging circuit. At least two signal acquisition terminals of the controller are respectively connected to the at least two state detection modules; At least two status signal output terminals of the controller are connected to the input terminals of the switch control module in the DC bus charging resistor overload protection circuit.

8. The DC charging circuit according to claim 7, characterized in that, The at least two status detection modules include a charging status detection module and a fan control module; The charging status detection module is connected to the DC bus of the DC charging circuit. The fan control module is connected in parallel with the charging capacitor of the DC charging circuit.

9. A frequency converter, characterized in that, It includes a rectifier section, an inverter section, and a DC charging circuit as described in claim 7 or 8, wherein the DC charging circuit is disposed between the rectifier section and the inverter section.

10. An air conditioning device, characterized in that, The device includes the frequency converter and compressor as described in claim 9, wherein the three-phase power input terminal of the compressor is connected to the three-phase output terminal of the frequency converter.

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