A DC bus protection circuit, a circuit system and an outdoor unit of an air conditioner

Abstract

The present invention relates to a DC bus protection circuit, a circuit system and an outdoor unit of an air conditioner. The DC bus protection circuit includes a detection module and a protection module. Among them, the detection module is connected to a load through a bus and is used for detecting an electrical signal flowing through the bus. The protection module is respectively connected to an input power supply and the detection module through the bus and is used for controlling the connection and disconnection of the input power supply and the load according to the electrical signal. The DC bus protection circuit of the present invention can quickly disconnect the input power supply and the load when a small-capacity bus capacitor is broken down and when a short circuit occurs between the positive and negative poles of the bus in a special working environment, thereby protecting the air conditioner drive board from being damaged and having high reliability. In addition, the protection circuit can detect the bus current without an additional voltage or current detection circuit, greatly reducing the cost of the circuit.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic circuits, and particularly relates to a DC bus protection circuit, a circuit system, and an outdoor unit of an air conditioner. Background Art

[0002] For an inverter technology drive solution without a storage capacitor, after replacing an electrolytic capacitor with a large capacitance value with a thin film capacitor with a small capacitance value, there will be ripples in the bus voltage. If the power grid fluctuates greatly, an instantaneous impact will be generated, and this instantaneous impact is very likely to cause the bus capacitor to be broken down, resulting in a short circuit between the positive and negative poles of the DC bus. In addition, the outdoor unit of an air conditioner usually works in harsh environments such as outdoors, especially in special working condition places such as fiber factories and graphite factories. Conductive substances such as fibers, dust, and graphite molecules scattered in the air may fall on the drive board of the outdoor unit of the air conditioner. Especially when they fall on both ends of the positive and negative poles of the bus, it will cause a short circuit, resulting in a blown board and triggering an accident. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to overcome the deficiencies of the prior art and provide a DC bus protection circuit, a circuit system, and an outdoor unit of an air conditioner.

[0004] To achieve the above purpose, the present invention adopts the following technical solutions: A DC bus protection circuit includes:

[0005] A detection module and a protection module;

[0006] Wherein, the detection module is connected to the load through the bus and is used to detect the electrical signal flowing through the bus;

[0007] The protection module is respectively connected to the input power supply and the detection module through the bus and is used to control the connection and disconnection of the input power supply and the load according to the electrical signal.

[0008] Optionally, the protection module includes:

[0009] A first switching tube and a second switching tube;

[0010] The emitter of the first switching tube is connected to the positive pole of the input power supply through the bus, the base of the first switching tube is connected to the collector of the second switching tube, the collector of the first switching tube and the base of the second switching tube are connected in parallel and then connected to the first drive signal terminal, and the emitter of the second switching tube is respectively connected to the second drive signal terminal and the detection module.

[0011] Optionally, the first switching tube is a PNP type triode or a PNP type field effect tube;

[0012] The second switching tube is an NPN type triode or an NPN type field effect tube.

[0013] Optionally, the detection module includes:

[0014] A transformer and a first capacitor;

[0015] One end of the primary side winding of the transformer is connected to the emitter of the second switching transistor, and the other end is connected to the negative electrode of the first capacitor; one end of the secondary side winding of the transformer is connected to the negative electrode of the first capacitor, and the other end is connected to the load through a busbar;

[0016] One end of the primary side winding of the transformer and one end of the secondary side winding are in-phase ends;

[0017] The positive electrode of the first capacitor is respectively connected to the negative electrode of the input power supply and the load through a busbar.

[0018] Optionally, a diode is also anti-parallel connected across both ends of the primary side winding of the transformer.

[0019] Optionally, the protection circuit further includes:

[0020] A current-limiting resistor;

[0021] The current-limiting resistor is arranged between the negative electrode of the first capacitor and the other end of the primary side winding of the transformer.

[0022] The present invention also provides a circuit system, including:

[0023] The protection circuit as described in any one of the preceding items; and,

[0024] A load and an input power supply connected to the protection circuit.

[0025] Optionally, the circuit system further includes:

[0026] A second capacitor;

[0027] The second capacitor is connected in parallel with the load.

[0028] Optionally, the circuit system is an air conditioner drive system.

[0029] The present invention also provides an outdoor unit of an air conditioner, including: the circuit system as described in any one of the items.

[0030] The present invention adopts the above technical solutions. The DC bus protection circuit includes a detection module and a protection module. Among them, the detection module is connected to a load through a bus and is used to detect the electrical signal flowing through the bus. The protection module is respectively connected to an input power supply and the detection module through the bus and is used to control the connection and disconnection of the input power supply and the load according to the electrical signal. The DC bus protection circuit of the present invention can quickly disconnect the input power supply and the load when a small-capacity bus capacitor is broken down and when a short circuit occurs between the positive and negative poles of the bus in a special working environment, thereby protecting the air-conditioning drive board from being damaged and having high reliability. In addition, the protection circuit can detect the bus current without an additional voltage or current detection circuit, greatly reducing the cost of the circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0032] Figure 1 is a schematic structural diagram provided by Embodiment 1 of the DC bus protection circuit of the present invention;

[0033] Figure 2 is a schematic structural diagram provided by Embodiment 2 of the DC bus protection circuit of the present invention;

[0034] Figure 3 is a schematic structural diagram provided by Embodiment 1 of the circuit system of the present invention.

[0035] In the figure: 1. Detection module; 2. Protection module; 3. First switching tube; 4. Second switching tube; 5. Load; 6. Input power supply; 7. Protection circuit. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0036] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be described in detail below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art without creative efforts based on the embodiments of the present invention belong to the scope protected by the present invention.

[0037] Figure 1 is a schematic structural diagram provided by Embodiment 1 of the DC bus protection circuit of the present invention.

[0038] As Figure 1 shown, the DC bus protection circuit described in this embodiment includes:

[0039] Detection module 1 and protection module 2;

[0040] Among them, the detection module 1 is connected to the load 5 through a busbar and is used to detect the electrical signal flowing through the busbar;

[0041] The protection module 2 is respectively connected to the input power supply 6 and the detection module 1 through a busbar, and is used to control the connection and disconnection of the input power supply 6 and the load 5 according to the electrical signal.

[0042] The protection circuit described in this embodiment detects the current flowing through the busbar through the detection module 1, and the current is input into the protection module 2. Under normal circumstances, that is, when the positive and negative poles of the busbar do not short-circuit, the current flows into the protection module 2 in a predetermined direction. The protection module 2 controls the connection of the input power supply 6 and the load 5 according to the current, so that the input power supply 6 supplies power to the load 5; when the positive and negative poles of the busbar short-circuit, the direction of the current is opposite to the predetermined direction. After the current flows into the protection module 2, the protection module 2 controls the input power supply 6 and the load 5 to disconnect, and stops supplying power to the load 5 to protect the load 5.

[0043] The DC busbar protection circuit described in this embodiment can quickly disconnect the input power supply 6 and the load 5 when the positive and negative poles of the busbar short-circuit in a special working environment, thereby protecting the air-conditioning drive board from being damaged and having high reliability; in addition, this protection circuit can detect the busbar current without an additional voltage or current detection circuit, greatly reducing the cost of the circuit.

[0044] Figure 2 It is a schematic structural diagram provided by the second embodiment of the DC busbar protection circuit of the present invention.

[0045] As Figure 2 shown, the DC busbar protection circuit described in this embodiment includes:

[0046] Detection module 1 and protection module 2;

[0047] Among them, the detection module 1 is connected to the load 5 through a busbar and is used to detect the electrical signal flowing through the busbar;

[0048] The protection module 2 is respectively connected to the input power supply 6 and the detection module 1 through a busbar, and is used to control the connection and disconnection of the input power supply 6 and the load 5 according to the electrical signal.

[0049] Furthermore, the protection module 2 includes:

[0050] The first switching tube 3 and the second switching tube 4;

[0051] The emitter of the first switch tube 3 is connected to the positive electrode of the input power supply 6 through a busbar, the base of the first switch tube 3 is connected to the collector of the second switch tube 4, and the collector of the first switch tube 3 and the base of the second switch tube 4 are connected in parallel to the first drive signal terminal ( Figure 2 The gate (G) of the second switch tube 4 is connected to the gate (G) of the second switch tube 4, and the emitter of the second switch tube 4 is connected to the second drive signal terminal ( Figure 2 The cathode (C) in the detector is connected to the detection module 1.

[0052] Furthermore, the first switch tube 3 is a PNP transistor or a PNP field effect tube;

[0053] The second switch tube 4 is an NPN transistor or an NPN field effect tube.

[0054] Furthermore, the detection module 1 includes:

[0055] A transformer and a first capacitor;

[0056] One end of the primary winding of the transformer is connected to the emitter of the second switch tube 4, and the other end is connected to the negative electrode of the first capacitor; one end of the secondary winding of the transformer is connected to the negative electrode of the first capacitor, and the other end is connected to the load 5 through the busbar;

[0057] One end of the primary winding of the transformer and one end of the secondary winding are in-phase ends;

[0058] The positive electrode of the first capacitor is connected to the negative electrode of the input power supply 6 and the load 5 through a bus bar.

[0059] Furthermore, a diode is anti-parallel connected at both ends of the primary winding of the transformer.

[0060] Furthermore, the protection circuit also includes:

[0061] Current limiting resistor;

[0062] The current limiting resistor is arranged between the negative electrode of the first capacitor and the other end of the primary winding of the transformer.

[0063] Figure 2 In the figure, the first switch tube 3 and the second switch tube 4 are connected in series to the positive pole of the busbar. D is an anti-parallel diode on the primary winding of the transformer, which plays a freewheeling role. N1 / N2 is the ratio of the number of gates on the primary and secondary sides of the transformer. R is a current limiting resistor used to prevent the short-circuit current i f Too much damage to the first capacitor C; i S is the power supply input current, i Ois the output current of the DC bus. The purpose of the DC bus protection circuit in this embodiment is to quickly disconnect the input power supply 6 and the load 5 when a short circuit occurs between the positive and negative ends of the bus, thereby protecting the drive board from being damaged.

[0064] The working principle of the protection circuit in this embodiment is as follows:

[0065] 1. During normal operation, by providing a positive voltage pulse signal to the G and C electrodes of the drive signal terminal, the second switching tube 4 is continuously turned on, and at the same time, the first switching tube 3 is also turned on. After the input current passes through the first switching tube 3, the second switching tube 4, and the primary side of the transformer, it is output as current i O to the external load 5, such as a compressor. Since the input current i S is direct current, there will be no induced current on the secondary side of the transformer. Even if some AC components enter the secondary side, they can be filtered by the first capacitor C.

[0066] 2. When a short circuit occurs between the positive and negative poles of the bus, this fault will generate an impact current i c in the branch including the first capacitor C and the secondary winding of the transformer. The impact current i c will increase with the increase of the short - circuit time. This current will generate an induced current on one side of the transformer, and its direction is opposite to the normal working current.

[0067] 3. When the current induced from the primary side of the transformer gradually rises, it will reduce the current flowing through the second switching tube 4 to zero, thereby turning off both the first switching tube 3 and the second switching tube 4, and then quickly disconnecting the input power supply 6 and the load 5, so as to protect the drive board from being damaged.

[0068] It should be noted that after the first switching tube 3 and the second switching tube 4 are turned off, they will remain in the off state if there is no drive signal; under normal conditions of the positive and negative poles of the bus, once the first switching tube 3 and the second switching tube 4 are turned on, they can remain in the on state even without a drive signal.

[0069] 4. By setting the transformer turns ratio N1 / N2, the magnitude of the induced current on the primary side can be changed, so that the protection circuit will not recognize the instantaneous impact caused by a large change in the load 5 as a short - circuit fault.

[0070] The DC bus protection circuit described in this embodiment can quickly disconnect the input power supply 6 and the load 5 when the small - capacitance bus capacitor is broken down and when a short circuit occurs between the positive and negative poles of the bus in a special working environment, thereby protecting the air - conditioner drive board from being damaged. The protection speed is fast and the reliability is high; in addition, this protection circuit is a hardware - level protection, and it can detect the bus current without an additional voltage or current detection circuit, greatly reducing the cost of the circuit.

[0071] Figure 3 It is a schematic structural diagram provided by the first embodiment of the circuit system of the present invention.

[0072] As Figure 3 shown, the circuit system described in this embodiment includes:

[0073] The protection circuit 7 as described in any one of the foregoing; and,

[0074] The load 5 and the input power supply 6 connected to the protection circuit.

[0075] Furthermore, the circuit system further includes:

[0076] The second capacitor C dc ;

[0077] The second capacitor is connected in parallel with the load 5.

[0078] Furthermore, the circuit system is an air conditioner drive system.

[0079] Figure 3 In, the second capacitor C dc is a DC bus capacitor with a small capacitance value.

[0080] The circuit system described in this embodiment can, through the protection circuit 7, achieve that in normal circumstances, that is, when the positive and negative poles of the bus do not short-circuit, control the connection of the input power supply 6 and the load 5, so that the input power supply 6 supplies power to the load 5; in abnormal circumstances, that is, when the positive and negative poles of the bus short-circuit, control the disconnection of the input power supply 6 and the load 5, and stop supplying power to the load 5 to protect the load 5. The circuit system described in this embodiment can quickly disconnect the input power supply 6 and the load 5 when the small-capacitance bus capacitor is broken down, or when the positive and negative poles of the bus short-circuit in a special working environment, thereby preventing the circuit board from exploding.

[0081] The circuit system described in this embodiment is safer and more reliable because it adopts the protection circuit 7.

[0082] In addition, the present invention also provides an implementation manner of an outdoor unit of an air conditioner. The outdoor unit of the air conditioner described in this implementation manner includes:

[0083] As Figure 3 the circuit system described.

[0084] It can be understood that the same or similar parts in the above embodiments can be referred to each other, and the content not detailed in some embodiments can be referred to the same or similar content in other embodiments.

[0085] It should be noted that in the description of the present invention, terms such as "first", "second", etc. are only used for descriptive purposes and cannot be construed as indicating or implying relative importance. In addition, in the description of the present invention, unless otherwise specified, the meaning of "a plurality of" refers to at least two.

[0086] Any process or method description in the flowchart or described in other ways herein can be understood to represent a module, segment, or part of code including one or more executable instructions for implementing a specific logical function or process. The scope of the preferred embodiments of the present invention includes additional implementations, where the functions can be executed in a substantially simultaneous manner or in a reverse order according to the involved functions, rather than in the order shown or discussed. This should be understood by those skilled in the technical field to which the embodiments of the present invention belong.

[0087] It should be understood that each part of the present invention can be implemented by hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, any one or a combination of the following well-known techniques in the art can be used: discrete logic circuits with logic gate circuits for implementing logical functions on data signals, application-specific integrated circuits with appropriate combinational logic gate circuits, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0088] Those of ordinary skill in the technical field can understand that all or part of the steps carried by the method of the above embodiments can be completed by instructing relevant hardware through a program. The program can be stored in a computer-readable storage medium. When the program is executed, it includes one or a combination of the steps of the method embodiments.

[0089] In addition, each functional unit in various embodiments of the present invention can be integrated into a processing module, or each unit can exist physically alone, or two or more units can be integrated into a module. The above integrated module can be implemented in the form of hardware or in the form of a software functional module. When the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

[0090] The above-mentioned storage medium can be a read-only memory, a magnetic disk, an optical disk, etc.

[0091] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0092] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A DC bus protection circuit, characterized in that Comprising: A detection module and a protection module; Wherein, the detection module is connected to a load through a bus, and is used to detect the electrical signal of the current flowing through the bus; The protection module is respectively connected to an input power supply and the detection module through the bus, and is used to control the connection and disconnection of the input power supply and the load according to the electrical signal of the current, including: if the flow direction of the current is the same as the predetermined direction, then control the input power supply to be connected to the load, if the flow direction of the current is opposite to the predetermined direction, then control the input power supply to be disconnected from the load; The protection module includes: A first switching tube and a second switching tube; The emitter of the first switching tube is connected to the positive pole of the input power supply through the bus, the base of the first switching tube is connected to the collector of the second switching tube, the collector of the first switching tube and the base of the second switching tube are connected in parallel and then connected to a first drive signal terminal, and the emitter of the second switching tube is respectively connected to a second drive signal terminal and the detection module; The detection module includes: a transformer and a first capacitor; one end of the primary side winding of the transformer is connected to the emitter of the second switching tube, and the other end is connected to the negative pole of the first capacitor; one end of the secondary side winding of the transformer is connected to the negative pole of the first capacitor, and the other end is connected to the load through the bus; one end of the primary side winding of the transformer and one end of the secondary side winding are in-phase ends; the positive pole of the first capacitor is respectively connected to the negative pole of the input power supply and the load through the bus.

2. The protection circuit according to claim 1, wherein The first switching tube is a PNP type triode or a PNP type field effect transistor; The second switching tube is an NPN type triode or an NPN type field effect transistor.

3. The protection circuit according to claim 1, characterized in that, A diode is also anti-parallel connected across both ends of the primary side winding of the transformer.

4. The protection circuit according to claim 1, characterized in that, Further comprising: A current limiting resistor; The current limiting resistor is arranged between the negative pole of the first capacitor and the other end of the primary side winding of the transformer.

5. A circuit system, characterized in that, Comprising: The protection circuit according to any one of claims 1-4; And, A load and an input power supply connected to the protection circuit.

6. The circuit system according to claim 5, wherein Further comprising: A second capacitor; The second capacitor is connected in parallel with the load.

7. The circuit system according to claim 5 or 6, characterized in that, The circuit system is an air conditioner drive system.

8. An outdoor unit of an air conditioner, characterized in that, Comprising: The circuit system according to any one of claims 5-7.

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