Power supply unit for inverter air conditioner and inverter air conditioner

Abstract

This utility model discloses a power supply device for a variable frequency air conditioner. The power supply device includes a first power terminal, a second power terminal, a current-limiting resistor, a relay, a rectifier bridge, a capacitor, and an overcurrent protection circuit. The capacitor supplies power to the load. The overcurrent protection circuit determines the bus current value between the capacitor and the rectifier bridge. When the detected bus current value exceeds a preset current value, the circuit controls the relay to disconnect, causing the current-limiting resistor to limit the current. This device can provide current-limiting protection when the detected bus current value is too high, preventing the capacitor from being subjected to a large current surge.

Description

Technical Field

[0001] This utility model relates to the field of air conditioning technology, and in particular to a power supply device for a variable frequency air conditioner and a variable frequency air conditioner. Background Technology

[0002] In order to control the inverter compressor, inverter air conditioners usually need to first convert AC power to stable DC power and then charge the capacitor. When the inverter air conditioner is powered on for the first time, a current-limiting resistor is connected in series in the circuit to limit the inrush current.

[0003] In related technologies, in order to improve working efficiency, the current-limiting resistor is short-circuited when the inverter air conditioner is working normally. However, due to the instability of the power grid in some areas, the voltage is unstable, resulting in a large voltage difference between the input voltage and the capacitor, generating inrush current. At this time, the current-limiting resistor cannot play the role of limiting the inrush current. Utility Model Content

[0004] The present invention aims to at least solve one of the technical problems existing in the prior art. Therefore, one objective of the present invention is to provide a power supply device for a variable frequency air conditioner, which can provide current limiting protection when an excessive bus current is detected, thereby preventing the capacitor from being subjected to a large current surge.

[0005] The second objective of this utility model is to propose a variable frequency air conditioner.

[0006] The first aspect of this utility model provides a power supply device for a variable frequency air conditioner, comprising a first power supply terminal and a second power supply terminal; a current-limiting resistor, the first end of which is connected to the first power supply terminal; a relay, the first end of which is connected to the first end of the current-limiting resistor, and the second end of which is connected to the second end of the current-limiting resistor; a rectifier bridge, the first end of which is connected to the second end of the relay and the second end of the current-limiting resistor, and the second end of which is connected to the second power supply terminal; a capacitor, the first end of which is connected to the third end of the rectifier bridge, and the second end of which is grounded, the capacitor being used to supply power to the load; and an overcurrent protection circuit, the overcurrent protection circuit being connected to the fourth end of the rectifier bridge and the control terminal of the relay, the overcurrent protection circuit being used to determine the bus current value between the capacitor and the rectifier bridge, and when the bus current value is detected to be greater than a preset current value, controlling the relay to disconnect so that the current-limiting resistor limits the current.

[0007] According to the power supply device for inverter air conditioners according to the present invention, an overcurrent protection circuit is provided. The overcurrent protection circuit detects the bus current value and compares it with a preset current value. Thus, when the bus current value is detected to be too large, the relay is controlled to disconnect and a current-limiting resistor is connected. The current-limiting resistor is used to limit the current and prevent the capacitor from being impacted by a large current.

[0008] In some embodiments, the overcurrent protection circuit includes: a detection module, the first end of which is connected to the fourth end of the rectifier bridge, and the second end of which is connected to the second end of the capacitor, the detection module being used to detect the bus current value; and a comparison module, the first end of which is connected to the first end of the detection module, the second end of which is connected to the second end of the detection module, and the third end of which is connected to the control terminal of the relay, the comparison module being used to control the relay to disconnect when the bus current value is greater than a preset current value.

[0009] In some embodiments, the comparison module includes: a first voltage divider unit, a first terminal of which is connected to a reference power supply, and a second terminal of which is connected to a second terminal of the detection module; a second voltage divider unit, a first terminal of which is connected to the first terminal of the first voltage divider unit and the reference power supply, and a second terminal of which is connected to the first terminal of the detection module; and a comparison unit, a non-inverting input terminal of which is connected to a third terminal of the first voltage divider unit, an inverting input terminal of which is connected to a third terminal of the second voltage divider unit, and an output terminal of which is connected to the control terminal of the relay.

[0010] In some embodiments, the first voltage divider unit includes: a first resistor, a first end of which is connected to the reference power supply, and a second end of which is connected to the non-inverting input of the comparator unit; and a second resistor, a first end of which is connected to the second end of the first resistor and the non-inverting input of the comparator unit, and a second end of which is connected to the second end of the detection module.

[0011] In some embodiments, the second voltage divider unit includes: a third resistor, the first end of which is connected to the first end of the first voltage divider unit and the reference power supply, and the second end of which is connected to the inverting input terminal of the comparator unit; and a fourth resistor, the first end of which is connected to the second end of the third resistor and the inverting input terminal of the comparator unit, and the second end of which is connected to the first end of the detection module.

[0012] In some embodiments, the comparison unit includes: a comparator, the power supply terminal of which is connected to a power supply, the non-inverting input terminal of which is connected to the third terminal of the first voltage divider unit, the inverting input terminal of which is connected to the third terminal of the second voltage divider unit, the output terminal of which is connected to the control terminal of the relay, and the ground terminal of which is grounded; and a fifth resistor, the first terminal of which is connected to the power supply terminal of the comparator, and the second terminal of which is connected to the output terminal of the comparator and the control terminal of the relay.

[0013] In some embodiments, the detection module includes: a sixth resistor, the first end of which is connected to the fourth end of the rectifier bridge and the first end of the comparison module, and the second end of which is connected to the second end of the capacitor and the second end of the comparison module.

[0014] In some embodiments, the capacitor is an electrolytic capacitor.

[0015] In some embodiments, the first power supply terminal is the live wire terminal, and the second power supply line is the neutral wire terminal.

[0016] The second aspect of this utility model provides a variable frequency air conditioner, including the power supply device for the variable frequency air conditioner described in the above embodiment.

[0017] The variable frequency air conditioner according to the present invention employs a power supply device that can perform current limiting protection when the bus current value is detected to be too high, thereby preventing the capacitor from being impacted by a large current.

[0018] In some embodiments, the inverter air conditioner further includes: a power conversion module, wherein a first input terminal of the power conversion module is connected to a first terminal of a capacitor, and a second input terminal of the power conversion module is connected to a second terminal of the capacitor; and a control module, wherein a power supply terminal of the control module is connected to an output terminal of the power conversion module, a ground terminal of the control module is grounded, and a control terminal of the control module is connected to a control terminal of the relay.

[0019] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0020] The above and / or additional aspects and advantages of this utility model will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0021] Figure 1 This is a structural block diagram of a power supply device for a variable frequency air conditioner according to an embodiment of the present invention;

[0022] Figure 2 This is a circuit topology diagram of an inverter air conditioner according to an embodiment of the present invention;

[0023] Figure 3 This is a schematic diagram of the internal current flow of a power supply device during the positive half-cycle of alternating current.

[0024] Figure 4 This is a schematic diagram of the internal current flow of a power supply device during the negative half-cycle of alternating current.

[0025] Figure 5 This is a schematic diagram of the current flow direction during the positive half-cycle of alternating current according to an embodiment of the present invention;

[0026] Figure 6 This is a schematic diagram of the current flow direction during the negative half-cycle of AC power according to an embodiment of the present invention;

[0027] Figure 7 This is a structural block diagram of a surge protection circuit according to an embodiment of the present invention;

[0028] Figure 8 A structural block diagram of a comparison module according to an embodiment of the present invention;

[0029] Figure 9 This is a structural block diagram of an inverter air conditioner according to an embodiment of the present invention.

[0030] Figure label:

[0031] 1000 inverter air conditioner;

[0032] Power supply device 100 for inverter air conditioner;

[0033] Overcurrent protection circuit 10; power conversion module 20; control module 30

[0034] First voltage divider unit 21; Second voltage divider unit 22; Comparison unit 23;

[0035] First power supply terminal L; Second power supply terminal N; Current limiting resistor RT1; Relay K1; Rectifier bridge VC1; Capacitor E1; First resistor R1; Second resistor R2; Third resistor R3; Fourth resistor R4; Comparator N1; Fifth resistor R5; Sixth resistor R6. Detailed Implementation

[0036] The embodiments of the present invention are described in detail below. The embodiments described with reference to the accompanying drawings are exemplary. The embodiments of the present invention are described in detail below.

[0037] In related technologies, variable frequency air conditioners typically need to convert AC power to stable DC power to control the variable frequency compressor. Upon initial power-on, the AC power first passes through a current-limiting resistor before entering the rectifier bridge and finally input to the capacitor. Because the capacitor's equivalent impedance during charging is very low, the inrush current during initial charging is very large. To limit this inrush current and protect the capacitor from damage, a current-limiting resistor is connected in series during initial power-on. For example, with an input voltage of 220V and an equivalent resistance of 2Ω, the charging current can reach 110A without the current-limiting resistor. By designing the current-limiting resistor to have a resistance of 50Ω and connecting it in series in the circuit, the charging current can be reduced to 4.23A, a significant reduction. Furthermore, after the capacitor is charging, shorting the current-limiting resistor prevents unnecessary power consumption caused by current flowing through it.

[0038] However, in some areas with unstable power grids, when the voltage is unstable, a large voltage difference will be generated between the input voltage and the voltage across the capacitor, resulting in inrush current. For example, when the input voltage drops from 220V to 120V, the voltage across the capacitor will also drop. When the voltage returns to 220V, the current-limiting resistor is short-circuited and cannot limit the current. At this time, the inrush current is 50A. Long-term exposure to inrush current will also shorten the lifespan of the capacitor.

[0039] To address the aforementioned issues, the first aspect of this utility model proposes a power supply device for a variable frequency air conditioner. This device can provide current limiting protection when an excessive bus current value is detected, thereby preventing the capacitor from being impacted by a large current.

[0040] The following is for reference. Figure 1 and Figure 2 The power supply device 100 for a variable frequency air conditioner according to an embodiment of the present invention is described, such as... Figure 2 As shown, the power supply device 100 includes a first power supply terminal L, a second power supply terminal N, a current limiting resistor RT1, a relay K1, a rectifier bridge VC1, a capacitor E1, and an overcurrent protection circuit 10.

[0041] In this circuit, the first end of the current-limiting resistor RT1 is connected to the first power supply terminal L; the first end of the relay K1 is connected to the first end of the current-limiting resistor RT1; the second end of the relay K1 is connected to the second end of the current-limiting resistor RT1; the first end of the rectifier bridge VC1 is connected to the second end of the relay K1 and the second end of the current-limiting resistor RT1; the second end of the rectifier bridge VC1 is connected to the second power supply terminal N; the first end of the capacitor E1 is connected to the third end of the rectifier bridge VC1; the second end of the capacitor E1 is grounded; the capacitor E1 is used to supply power to the load; the overcurrent protection circuit 10 is connected to the second power supply terminal N, the fourth end of the rectifier bridge VC1, and the control terminal of the relay K1; the overcurrent protection circuit 10 is used to determine the bus current value between the capacitor E1 and the rectifier bridge VC1, and when the bus current value is detected to be greater than the preset current value, it controls the relay K1 to open so that the current-limiting resistor RT1 can limit the current.

[0042] Specifically, after the air conditioner power plug is inserted, power is output through the first power terminal L and the second power terminal N. After capacitor E1 is fully charged, to avoid unnecessary power consumption, it controls relay K1 to be in a closed state. At this time, the current flows as follows: Figure 3 and Figure 4 As shown, Figure 3 This indicates the direction of current flow during the positive half-cycle of alternating current. Figure 4 To determine the current flow direction during the negative half-cycle of the AC power, relay K1 short-circuites the current-limiting resistor. However, if the power input is unstable, a large voltage difference will occur across capacitor E1. Since the equivalent impedance of capacitor E1 is very low, an inrush current will be generated, impacting capacitor E1. This application sets up an overcurrent protection circuit 10 to detect the bus current value. When an unstable power input causes an inrush current (i.e., the bus current value is too large), if it exceeds the preset current value, the comparison module 2 controls relay K1 to disconnect, thereby connecting a current-limiting resistor RT1 between the first power supply terminal L and the rectifier bridge VC1. Since the current-limiting resistor RT1 has a current-limiting function, it can prevent the excessive bus current from impacting capacitor E1, thus preventing damage to capacitor E1 due to the inrush current. The current-limiting resistor RT1 can be set as a positive temperature coefficient thermistor. When the current is larger, the thermistor heats up more and the resistance is higher, thereby limiting the current.

[0043] It should be noted that the preset current value can be set according to the capacitance of capacitor E1, for example, the preset current value can be set to 24A, 25A or 26A.

[0044] According to the power supply device 100 for a variable frequency air conditioner according to the present utility model embodiment, an overcurrent protection circuit 10 is provided. The bus current value is detected by the detection module 1. Then, based on the connection between the detection module 1 and the comparison module 2, the comparison module 2 compares the bus current value with a preset current value. Thus, when the bus current value is detected to be too large, the relay K1 is controlled to disconnect, so that the current limiting resistor RT1 is connected. The current limiting resistor RT1 is used to limit the current and prevent the capacitor from being impacted by a large current.

[0045] In some embodiments, such as Figure 2 and Figure 7 As shown, the overcurrent protection circuit 10 includes a detection module 1 and a comparison module 2. The first end of the detection module 1 is connected to the fourth end of the rectifier bridge VC1, and the second end of the detection module 1 is connected to the second end of the capacitor E1. The detection module 1 is used to detect the bus current value. The first end of the comparison module 2 is connected to the first end of the detection module 1, and the second end of the comparison module 2 is connected to the second end of the detection module 1. The third end of the comparison module 2 is connected to the control end of the relay K1. The comparison module 2 is used to control the relay K1 to disconnect when the bus current value is greater than the preset current value.

[0046] Specifically, the detection module 1 detects the bus current value, and based on the connection between the detection module 1 and the comparison module 2, the detection module 1 sends the detection result of the bus current value to the comparison module 2. When the power input is unstable and an inrush current occurs, i.e. the bus current value is too large, if it is greater than the preset current value, the comparison module 2 controls the relay K1 to open, thereby connecting the current limiting resistor RT1 between the first power supply terminal L and the rectifier bridge VC1. Since the current limiting resistor RT1 has a current limiting function, it can prevent the excessive bus current value from impacting the capacitor E1, so the capacitor E1 will not be damaged due to the inrush current. The current limiting resistor RT1 can be set as a positive temperature coefficient thermistor. When the current is larger, the thermistor heats up more and the resistance is higher, thereby playing the role of limiting the current.

[0047] In some embodiments, such as Figure 2 and Figure 8 As shown, the comparison module 2 includes a first voltage divider unit 21, a second voltage divider unit 22, and a comparison unit 23.

[0048] In this configuration, the first end of the first voltage divider unit 21 is connected to the reference power supply, the second end of the first voltage divider unit 21 is connected to the second end of the detection module 1, the first end of the second voltage divider unit 22 is connected to the first end of the first voltage divider unit 21 and the reference power supply, the second end of the second voltage divider unit 22 is connected to the first end of the detection module 1, the non-inverting input end of the comparison unit 23 is connected to the third end of the first voltage divider unit 21, the inverting input end of the comparison unit 23 is connected to the third end of the second voltage divider unit 22, and the output end of the comparison unit 23 is connected to the control end of the relay K1.

[0049] Specifically, a reference power supply is set according to the preset current value. Then, the first voltage divider unit 21 is connected to the reference power supply to provide a reference voltage to the non-inverting input terminal of the comparison unit 23. At the same time, the second voltage divider unit 22 can convert the bus current value detected by the detection module 1 into a measurement voltage and provide a measurement voltage to the inverting input terminal of the comparison unit 23. The comparison unit 23 compares the reference voltage and the measurement voltage, that is, compares the bus current value with the preset current value. Thus, when the measurement voltage is less than the reference voltage, a relay control signal is output through the output terminal of the comparison unit 23. The control terminal of the relay K1 receives the signal and controls the relay K1 to open, connecting a current-limiting resistor to provide current-limiting protection for the capacitor E1.

[0050] In some embodiments, such as Figure 2 As shown, the first voltage divider unit 21 includes a first resistor R1 and a second resistor R2.

[0051] The first end of the first resistor R1 is connected to the reference power supply, the second end of the first resistor R1 is connected to the non-inverting input of the comparison unit 23, the first end of the second resistor R2 is connected to the second end of the first resistor R1 and the non-inverting input of the comparison unit 23, and the second end of the second resistor R2 is connected to the second end of the detection module 2.

[0052] Specifically, since the connection point between the second terminal of the detection module 1 and the second resistor R2 is grounded, after the reference power supply provides voltage, based on the voltage division effect of the first resistor R1 and the second resistor R2, the voltage division at the connection point of the first resistor R1 and the second resistor R2 is a constant value, that is, the input voltage of the non-inverting input terminal of the comparison unit 23 is a constant value, which does not change with the power input of the first power supply terminal L and the second power supply terminal N. It is used as a reference to compare with the input voltage of the inverting input terminal of the comparison unit 23, so as to avoid the bus current value being too large and exceeding the capacity of the capacitor E1.

[0053] In some embodiments, such as Figure 2 As shown, the second voltage divider unit 22 includes a third resistor R3 and a fourth resistor R4.

[0054] Among them, the first end of the third resistor R3 is connected to the first end of the first voltage divider unit 21 and the reference power supply, the second end of the third resistor R3 is connected to the inverting input terminal of the comparator unit 23, the first end of the fourth resistor R4 is connected to the second end of the third resistor R3 and the inverting input terminal of the comparator unit 23, and the second end of the fourth resistor R4 is connected to the first end of the detection module 1.

[0055] Specifically, the first end of the fourth resistor R4 is connected between the detection module 1 and the rectifier bridge VC1. If the bus current value changes, based on the reference power supply, the voltage division value at the connection point of the third resistor R3 and the fourth resistor R4 will change under the voltage division effect of the third resistor R3 and the fourth resistor R4. That is, the input voltage of the inverting input terminal of the comparison unit 23 will change. If the bus current value is higher than the preset current value, the input voltage of the non-inverting input terminal of the comparison unit 23 will be greater than the voltage of the inverting input terminal of the comparison unit 23.

[0056] In some embodiments, such as Figure 2 As shown, the comparison unit 23 includes comparator N1 and fifth resistor R5.

[0057] The comparator N1 is connected to the power supply. The non-inverting input of the comparator N1 is connected to the third terminal of the first voltage divider unit 21. The inverting input of the comparator N1 is connected to the third terminal of the second voltage divider unit 22. The output of the comparator N1 is connected to the control terminal of the relay K1. The ground terminal of the comparator N1 is grounded. The first terminal of the fifth resistor R5 is connected to the power supply of the comparator N1. The second terminal of the fifth resistor R5 is connected to the output of the comparator N1 and the control terminal of the relay K1.

[0058] Specifically, resistor R5 is used as a pull-up resistor to pull the output of comparator N1 to the high level of the power supply. Therefore, when the bus current is higher than the preset current value (i.e., the input voltage at the non-inverting input of comparator N1 is greater than the voltage at the inverting input), the output voltage of N1 is the power supply voltage. At this time, there is no voltage difference across relay K1, meaning no current flows through the coil of relay K1, and relay K1 is open, allowing the current-limiting resistor to be connected to the circuit for current limiting. Conversely, if the input voltage at the non-inverting input of comparator N1 is less than or equal to the input voltage at the inverting input, the output of comparator N1 is grounded. At this time, the voltage difference across relay K1 is the power supply voltage, current flows through the coil of relay K1, relay K1 is closed, and the current-limiting resistor is short-circuited to avoid unnecessary power consumption. The power supply can be set according to actual conditions; no specific restrictions are imposed here.

[0059] In some embodiments, such as Figure 2 As shown, detection module 1 includes a sixth resistor R6.

[0060] The first end of the sixth resistor R6 is connected to the fourth end of the rectifier bridge VC1 and the first end of the comparator module 2, and the second end of the sixth resistor R6 is connected to the second end of the capacitor E1 and the second end of the comparator module 2.

[0061] Specifically, when current flows through the sixth resistor R6 on the bus, a voltage difference is generated across the sixth resistor R6. The second comparison unit 22 then converts the bus current value into a measurement voltage input to the inverting input of the comparator N1, which is compared with the reference voltage at the non-inverting input. This enables monitoring of the bus current value. On the one hand, it avoids unnecessary consumption caused by the current-limiting resistor. On the other hand, it limits the current when the bus current value is too large and may impact the capacitor E1.

[0062] For example, the resistances of the first resistor R1, the second resistor R2, and the fourth resistor R4 are 3KΩ, the resistance of the third resistor R3 is 3.3KΩ, and the resistance of the sixth resistor R6 is 10mΩ. The preset current value is set to 25A. When the bus current value is greater than 25A, the voltage difference across the sixth resistor R6 will be greater than 0.25V. Since the connection point of the second resistor R2 and the sixth resistor R6 is grounded, the voltage at the connection point of the second resistor R2 and the sixth resistor R6 is -0.25V. The voltage input to the inverting input of comparator N1 will be lower than 2.5V, while the voltage input to the non-inverting input of comparator N1 will be lower. The reference voltage at the terminal remains unchanged at 2.5V. Therefore, under the pull-up effect of the fifth resistor R5, the output of comparator N1 outputs a high level of 12V. The power supply voltage of the relay is also 12V. At this time, no current flows through the coil of relay K1, the relay is open, and the current-limiting resistor is connected in the circuit to limit the current. However, after the protection detects that the bus current value is less than 25A, the input voltage of the inverting input terminal of comparator N1 will be higher than 2.5V. At this time, the output of comparator N1 outputs a low level, current flows through the coil of relay K1, relay K1 is closed, and the inverter air conditioner works normally.

[0063] In some embodiments, capacitor E1 is an electrolytic capacitor.

[0064] Specifically, after rectification by rectifier bridge VC1, the high-voltage DC power is stored in high-voltage electrolytic capacitor E1, and the power output is provided by high-voltage electrolytic capacitor E1.

[0065] In some embodiments, the first power terminal L is the live wire terminal, and the second power wire N is the neutral wire terminal.

[0066] The second aspect of this utility model provides a variable frequency air conditioner 1000, such as... Figure 2 and Figure 9 As shown, the inverter air conditioner 1000 includes a power supply device 100 for the inverter air conditioner.

[0067] The variable frequency air conditioner 1000 according to this utility model embodiment can perform current limiting protection when the bus current value is detected to be too large, so as to avoid the capacitor being impacted by a large current.

[0068] In some embodiments, such as Figure 2 and Figure 9As shown, the inverter air conditioner 1000 includes a power conversion module 20 and a control module 30.

[0069] The first input terminal of the power conversion module 20 is connected to the first terminal of the capacitor E1, the second input terminal of the power conversion module 20 is connected to the second terminal of the capacitor E1, the power supply terminal of the control module 30 is connected to the output terminal of the power conversion module 20, the ground terminal of the control module 30 is grounded, and the control terminal of the control module 30 is connected to the control terminal of the relay K1.

[0070] Specifically, when the inverter air conditioner 1000 is working normally, since the power conversion module 20 is connected to capacitor E1 and control module 30, the power conversion module 20 can convert high-voltage DC power (e.g., 310VDC) into low-voltage DC power (e.g., 5V and 12V) used by control module 30 to power control module 30. Control module 30 can detect whether it receives a user's power-on or power-off signal to determine whether the inverter air conditioner 1000 needs to be turned on. When a power-on signal is detected, it controls relay K1 to close, and the inverter air conditioner 1000 starts running. When a power-off signal is received, it controls the air conditioner to enter standby mode. Simultaneously, control module 30 controls relay K1 to open. After the control chip module starts working, the control chip sends a control signal to relay K1, causing relay K1 to close. Current can then directly pass through rectifier bridge VC1 without passing through current-limiting resistor RT1, reducing the power consumption of inverter air conditioner 1000. It should be noted that this application controls relay K1 based on the change in the current value flowing through the bus, without the need for software monitoring and signal processing to send the control signal to relay K1, resulting in a more timely response.

[0071] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example.

[0072] Although embodiments of the present invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A power supply device for a variable frequency air conditioner, characterized in that, include: First power supply terminal and second power supply terminal; A current-limiting resistor, the first end of which is connected to the first power supply terminal; A relay, wherein a first terminal of the relay is connected to a first terminal of the current-limiting resistor, and a second terminal of the relay is connected to a second terminal of the current-limiting resistor; A rectifier bridge, wherein the first end of the rectifier bridge is connected to the second end of the relay and the second end of the current-limiting resistor, and the second end of the rectifier bridge is connected to the second power supply terminal; A capacitor, the first terminal of which is connected to the third terminal of the rectifier bridge, and the second terminal of which is grounded, is used to supply power to the load; An overcurrent protection circuit is provided, which is connected to the fourth terminal of the rectifier bridge, the second terminal of the capacitor, and the control terminal of the relay. The overcurrent protection circuit is used to determine the bus current value between the capacitor and the rectifier bridge, and when the bus current value is detected to be greater than a preset current value, it controls the relay to disconnect so that the current limiting resistor can limit the current.

2. The power supply device for a variable frequency air conditioner according to claim 1, wherein The overcurrent protection circuit includes: The detection module has a first end connected to the fourth end of the rectifier bridge and a second end connected to the second end of the capacitor. The detection module is used to detect the bus current value. The comparison module has a first terminal connected to the first terminal of the detection module, a second terminal connected to the second terminal of the detection module, and a third terminal connected to the control terminal of the relay. The comparison module is used to control the relay to disconnect when the bus current value is greater than a preset current value.

3. The power supply device for a variable frequency air conditioner according to claim 2, wherein The comparison module includes: A first voltage divider unit, the first end of which is connected to a reference power supply, and the second end of which is connected to the second end of the detection module; The second voltage divider unit has a first end connected to the first end of the first voltage divider unit and the reference power supply, and a second end connected to the first end of the detection module. The comparator unit has its non-inverting input connected to the third terminal of the first voltage divider unit, its inverting input connected to the third terminal of the second voltage divider unit, and its output connected to the control terminal of the relay.

4. The power supply device for a variable frequency air conditioner according to claim 3, wherein The first voltage divider unit includes: A first resistor, the first end of which is connected to the reference power supply, and the second end of which is connected to the non-inverting input terminal of the comparator unit; The second resistor has its first end connected to the second end of the first resistor and the non-inverting input of the comparison unit, and its second end connected to the second end of the detection module.

5. The power supply device for a variable frequency air conditioner according to claim 3, wherein The second voltage divider unit includes: The third resistor has its first end connected to the first end of the first voltage divider unit and the reference power supply, and its second end connected to the inverting input of the comparator unit. The fourth resistor has its first end connected to the second end of the third resistor and the inverting input of the comparison unit, and its second end connected to the first end of the detection module.

6. The power supply device for a variable frequency air conditioner according to claim 3, wherein The comparison unit includes: The comparator has its power supply terminal connected to the power supply, its non-inverting input terminal connected to the third terminal of the first voltage divider unit, its inverting input terminal connected to the third terminal of the second voltage divider unit, its output terminal connected to the control terminal of the relay, and its ground terminal grounded. The fifth resistor has its first end connected to the power supply terminal of the comparator, and its second end connected to the output terminal of the comparator and the control terminal of the relay.

7. The power supply device for a variable frequency air conditioner according to any one of claims 2 to 6, wherein The detection module includes: The sixth resistor has its first end connected to the fourth end of the rectifier bridge and the first end of the comparator module, and its second end connected to the second end of the capacitor and the second end of the comparator module.

8. The power supply device for a variable frequency air conditioner according to claim 1, wherein The capacitor is an electrolytic capacitor.

9. A variable frequency air conditioner, characterized in that, Includes the power supply device for a variable frequency air conditioner as described in any one of claims 1-8.

10. The variable frequency air conditioner according to claim 9, characterized in that, Also includes: A power conversion module, wherein a first input terminal of the power conversion module is connected to a first terminal of a capacitor, and a second input terminal of the power conversion module is connected to a second terminal of the capacitor; The control module has its power supply terminal connected to the output terminal of the power conversion module, its ground terminal grounded, and its control terminal connected to the control terminal of the relay.

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