Air conditioner outdoor unit

Abstract

This utility model relates to the field of air conditioning technology, and more particularly to an outdoor unit for air conditioning. The outdoor unit includes a casing, a compressor, and an inverter. The inverter includes a bridgeless PFC circuit, which comprises a main power circuit and a power factor correction circuit. The power factor correction circuit employs a single-sampling resistor and a comparator circuit structure to achieve overcurrent protection for the bridgeless PFC circuit. The sampling resistor is connected in series in the main power circuit of the bridgeless PFC circuit to convert the current signal to a voltage signal, and the bidirectional comparator circuit detects the overcurrent situation in real time during the positive and negative half-cycles. The comparator circuit includes a first comparator and a second comparator, used to detect forward and reverse overcurrents respectively. Their output signals drive a circuit to control the switching of the switching transistor, achieving rapid protection. This utility model simplifies the circuit structure, reduces power loss and cost, and simultaneously improves the response speed and reliability of overcurrent protection.

Description

Technical Field

[0001] This utility model relates to the field of air conditioning technology, and in particular to an outdoor unit of an air conditioner. Background Technology

[0002] With increasingly stringent global energy efficiency requirements and rapid development of power electronics technology, the power system design of household inverter air conditioners faces unprecedented technical challenges. Modern inverter air conditioners generally employ a two-stage power conversion structure: the front stage is a power factor correction (PFC) circuit, and the rear stage is an inverter drive circuit. Among these, the PFC circuit, as the first stage of the power system, directly determines the overall energy efficiency, electromagnetic compatibility characteristics, and system reliability of the unit.

[0003] In recent years, bridgeless PFC topology has gradually become the preferred solution for mid-to-high-end inverter air conditioners due to its high efficiency. Compared with traditional Boost PFC circuits, bridgeless PFC reduces the conduction losses of two diodes by eliminating the input rectifier bridge, theoretically improving the overall efficiency by 1.5%-3%. For household inverter air conditioners with rated power in the range of 1kW-3kW, this efficiency improvement means saving tens of kilowatt-hours of electricity per year, demonstrating significant energy-saving benefits.

[0004] However, while bridgeless PFC topologies offer efficiency advantages, they also introduce more complex protection issues. Because the natural isolation provided by the rectifier bridge is eliminated, the power switches in the circuit are directly exposed to the AC input voltage, significantly increasing the design complexity of current sensing and protection circuits. Especially in short-circuit protection, traditional solutions often struggle to balance the multiple requirements of response speed, protection accuracy, and system cost.

[0005] Currently, common current sampling solutions on the market include those based on Hall effect current sensors. Hall effect current sensors are non-contact current detection devices based on the Hall effect principle, indirectly obtaining the current value by measuring the magnetic field generated by the current. The main advantages of this solution are isolation from the main circuit, no additional conduction losses, and a wide bandwidth and measurement range. However, in bridgeless PFC circuit applications, Hall effect sensors have significant disadvantages such as slow response speed, complex signal conditioning circuits, and high cost. Another common solution is to connect two sampling resistors at the output of the power switch, and calculate the current value by measuring the voltage drop across the resistors. This solution has a fast response speed and moderate cost, much lower than Hall effect current sensors. However, this solution also has obvious drawbacks: the sampling resistors are directly connected in series in the rectifier circuit loop, which generates additional power loss; bridgeless PFC circuits usually need to monitor the current of two branches simultaneously, leading to an increase in the number of components, which in turn increases the overall cost and affects the competitiveness of the overall system in the market.

[0006] Therefore, how to achieve overcurrent protection function at low cost while ensuring overcurrent response speed has become an urgent problem to be solved. Utility Model Content

[0007] This utility model provides an outdoor air conditioning unit, which at least partially solves one of the technical problems in related technologies.

[0008] According to embodiments of this disclosure, an outdoor unit for an air conditioner is provided, comprising:

[0009] Shell: forms the shell cavity;

[0010] Compressor: disposed within the housing cavity;

[0011] Inverter: disposed in the housing and connected to the compressor, used to adjust the operating frequency of the compressor; the inverter includes a bridgeless PFC circuit; the bridgeless PFC circuit includes:

[0012] Main power circuit: It consists of a first bridge arm and a second bridge arm connected in parallel, and each bridge arm includes two diodes connected in series;

[0013] The power factor correction circuit includes:

[0014] First power switch: connected in parallel across a diode in the first bridge arm;

[0015] Second power switch: connected in parallel across a diode in the second bridge arm;

[0016] Sampling resistor: placed between the emitter stages of the first power switch and the second power switch;

[0017] Comparison circuit: Its input terminal is connected to both ends of the sampling resistor;

[0018] The driving circuit has its input terminal connected to the output terminal of the comparator circuit and its output terminal connected to the switching transistor, controlling the on / off state of the first power switching transistor and the second power switching transistor.

[0019] The technical solution provided in this application provides at least the following beneficial effects: The outdoor unit of the air conditioner provided in this solution replaces the Hall sensor in the prior art with a sampling resistor, converts the sampling of current into the sampling of voltage, and realizes the detection of the current of the rectifier circuit by judging the voltage signal across the sampling resistor through the comparison circuit, thereby realizing the overcurrent protection of the circuit.

[0020] In other embodiments of this application, the comparison circuit includes:

[0021] The first comparator circuit has its non-inverting input connected to the first terminal of the sampling resistor, its inverting input connected to the second terminal of the sampling resistor, and its output connected to the input terminal of the driving circuit.

[0022] The second comparator circuit has its inverting input connected to the first terminal of the sampling resistor, its non-inverting input connected to the second terminal of the sampling resistor, and its output connected to the input terminal of the driving circuit.

[0023] The above technical solution has the following advantages or beneficial effects: the comparator circuit processes the circuit in both positive and negative half-cycles at the same time, the first comparator circuit detects positive overcurrent, and the second comparator circuit detects reverse overcurrent. Bidirectional current protection can be achieved without additional complex circuits, which simplifies the overall circuit design and reduces the difficulty of circuit implementation.

[0024] In other embodiments of this application, the first comparator circuit includes:

[0025] The first voltage limiting resistor has one end connected to the first end of the sampling resistor;

[0026] The second voltage-limiting resistor is connected at one end to the second end of the sampling resistor;

[0027] The first comparator has its non-inverting input connected to the other end of the first voltage-limiting resistor, its inverting input connected to the other end of the sampling second voltage-limiting resistor, and its output connected to the input of the driving circuit.

[0028] The above technical solution has the following advantages or beneficial effects: when the positive current in the main power circuit flows through the sampling resistor, the non-inverting input terminal and the inverting input terminal of the first comparator collect the voltage signals across the sampling resistor for comparison and judgment; the setting of the first voltage limiting resistor and the second voltage limiting resistor restricts the current flow and avoids damage to the first comparator caused by excessive current.

[0029] In other embodiments of this application, the first comparator circuit includes:

[0030] The first hysteresis adjustment resistor has one end connected to the output terminal of the first comparator and the other end connected to the non-inverting input terminal of the first comparator.

[0031] The above technical solution has the following advantages or beneficial effects: the first hysteresis regulating resistor and the first comparator form a positive feedback circuit, which provides hysteresis voltage to the circuit, thereby avoiding frequent jumps at the output terminal due to input signal noise or small fluctuations, and improving the anti-interference ability and stability of the circuit.

[0032] In other embodiments of this application, the first comparator circuit includes:

[0033] The filter capacitor has one end connected to the output of the first comparator and the other end grounded.

[0034] The above technical solution has the following advantages or beneficial effects: the filter capacitor filters out the high-frequency interference components of the signal at the output of the first comparator, smooths the output level, and prevents voltage jitter from affecting the back-end circuit.

[0035] In other embodiments of this application, the first comparator circuit includes:

[0036] The first bias resistor has one end connected to the non-inverting input of the first comparator and the other end connected to the reference voltage.

[0037] The second bias resistor is connected at one end to the inverting input of the second comparator and at the other end to the reference voltage.

[0038] The above technical solution has the following advantages or beneficial effects: the first bias resistor and the second bias resistor provide a reference voltage for the circuit, ensuring that the output voltage of the first comparator remains at a positive potential during both the positive and negative half-cycles of the AC power supply.

[0039] In other embodiments of this application, the second comparator circuit includes:

[0040] The third voltage-limiting resistor is connected at one end to the second end of the sampling resistor;

[0041] The fourth voltage-limiting resistor is connected at one end to the first end of the sampling resistor;

[0042] The second comparator has its non-inverting input connected to the other end of the third voltage-limiting resistor, its inverting input connected to the other end of the sampling fourth voltage-limiting resistor, and its output connected to the input of the driving circuit.

[0043] The above technical solution has the following advantages or beneficial effects: when the reverse current in the main power circuit flows through the sampling resistor, the non-inverting input terminal and the inverting input terminal of the first comparator collect the voltage signals across the sampling resistor for comparison and judgment; the setting of the third voltage limiting resistor and the fourth voltage limiting resistor restricts the current flow and avoids damage to the first comparator caused by excessive current.

[0044] In other embodiments of this application, the second comparator circuit includes:

[0045] The second hysteresis adjustment resistor is connected at one end to the output terminal of the second comparator and at the other end to the non-inverting input terminal of the second comparator.

[0046] The above technical solution has the following advantages or beneficial effects: the second hysteresis regulating resistor and the first comparator form a positive feedback circuit, which provides hysteresis voltage to the circuit, thereby avoiding frequent jumps at the output terminal due to input signal noise or small fluctuations, and improving the anti-interference ability and stability of the circuit.

[0047] In other embodiments of this application, the second comparator circuit includes:

[0048] The third bias resistor is connected at one end to the non-inverting input of the second comparator and at the other end to the reference voltage.

[0049] The fourth bias resistor is connected at one end to the inverting input of the second comparator and at the other end to the reference voltage.

[0050] The above technical solution has the following advantages or beneficial effects: the third bias resistor and the fourth bias resistor provide a reference voltage for the circuit, ensuring that the output voltage of the second comparator remains at a positive potential during both the positive and negative half-cycles of the AC power supply.

[0051] According to embodiments of this disclosure, an outdoor unit for an air conditioner is also provided, comprising:

[0052] The shell, forming a shell cavity;

[0053] The compressor is disposed within the housing cavity;

[0054] A frequency converter, disposed within the housing cavity and connected to the compressor, is used to regulate the operating frequency of the compressor; the frequency converter includes a bridgeless PFC circuit; the input terminal of the bridgeless PFC circuit is connected to an AC power supply, and includes:

[0055] Main power circuit: consists of a first bridge arm and a second bridge arm connected in parallel, each bridge arm including two diodes connected in series;

[0056] The power factor correction circuit includes:

[0057] First power switch: connected in parallel to both ends of the first bridge arm;

[0058] Second power switch: connected in parallel to both ends of the second bridge arm;

[0059] Sampling resistor: disposed between the emitters of the first power switch and the second power switch;

[0060] Comparison circuit: Its input terminal is connected to both ends of the sampling resistor;

[0061] AC sampling circuit: Connected to an AC power supply to sample the voltage of the AC power supply;

[0062] Control chip: Its input terminal is connected to the output terminal of the comparator circuit and the output terminal of the AC sampling circuit;

[0063] The driving circuit has its input terminal connected to the output terminal of the comparator circuit and the output terminal of the control chip, which is connected to the switching transistor to control the on / off state of the first power switching transistor and the second power switching transistor.

[0064] The technical solution provided in this application provides at least the following beneficial effects: The outdoor unit of the air conditioner provided in this solution adjusts the phase difference between the AC input power supply and the main power circuit current through the control chip, thereby achieving synchronization between the AC input power supply and the main power current, thereby improving the power conversion efficiency of the main power circuit, enabling the inverter to more effectively control the load operation, and ultimately enabling the whole unit to achieve a higher energy efficiency standard.

[0065] Compared with existing technologies, this utility model uses a single sampling resistor to monitor the current signal of the main power circuit by converting the acquisition of the resistor current signal into the acquisition of the voltage signal across the resistor, thereby realizing the overcurrent protection function of the circuit. Compared with existing sampling resistor schemes, it reduces the number of sampling resistors on the main power circuit, thereby reducing the losses caused by the sampling resistors on the main power circuit, which improves energy efficiency and reduces material and production costs. At the same time, it avoids the large delay caused by the use of Hall sensor sampling in traditional schemes, significantly improving the response speed of overcurrent protection and enabling faster response to abnormal situations such as short circuits.

[0066] The above description is merely an overview of the technical solution disclosed herein. In order to better understand the technical means of this disclosure and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this disclosure more apparent and understandable, specific embodiments of this disclosure are described below. Attached Figure Description

[0067] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0068] Figure 1 , Figure 2 This is a three-dimensional structural view of the outdoor air conditioner unit in the embodiment;

[0069] Figure 3 This is a schematic diagram of the logic circuit of the frequency converter;

[0070] Figure 4 This is a schematic diagram of the inverter circuit.

[0071] Figure 5 This is a schematic diagram of the main power circuit of a bridgeless PFC circuit;

[0072] Figure 6 This is a schematic diagram of the power factor correction circuit for a bridgeless PFC circuit.

[0073] Figure 7 This is a detailed structural diagram of a bridgeless PFC circuit. Detailed Implementation

[0074] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0075] The prefixes such as "first" and "second" used in this application embodiment are merely for distinguishing different descriptive objects and do not limit the position, order, priority, quantity, or content of the described objects. The use of ordinal numbers and other prefixes used to distinguish descriptive objects in this application embodiment does not constitute a limitation on the described objects. The description of the described objects is given in the claims or the context of the embodiments, and should not constitute unnecessary restrictions due to the use of such prefixes. Furthermore, in the description of this embodiment, unless otherwise stated, "multiple" means two or more.

[0076] The technical solutions of the embodiments of this application will be described below with reference to the accompanying drawings. In the description of the embodiments of this application, unless otherwise stated, " / " means "or," for example, A / B can mean A or B; the term "and / or" in this document 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, and B existing alone.

[0077] In the embodiments provided in this application, it should be understood that the disclosed systems and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0078] In this application, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0079] This utility model provides an outdoor unit for an air conditioner. The outdoor unit for the air conditioner is described below with reference to the accompanying drawings.

[0080] refer to Figures 1-2 The outdoor unit 100 of the air conditioner includes a housing 1, which is installed outdoors and forms the overall appearance of the outdoor unit. The housing 1 also defines a storage space inside the housing for installing and fixing the various components of the outdoor unit.

[0081] Further reference Figures 1-2 The casing 1 also defines an outdoor air inlet 11 and an outdoor air outlet 12, both of which are connected to the housing space. The outdoor air inlet 11 serves as the inlet for external air to flow into the casing, while the outdoor air outlet 12 serves as the outlet for heat-exchanged air to flow out of the casing 1. Indoor air from outside the casing 1 enters the casing 1 through the indoor air inlet 11 and is finally discharged into the room through the outdoor air outlet 12.

[0082] Specifically, the outdoor air inlet 11 can be located on the rear side of the housing 1, and the outdoor air outlet 12 is located on the front side of the housing 1.

[0083] It should be noted that the directions described in the text are based on the direction the user faces when facing the outdoor unit of the air conditioner. Specifically, the side of the outdoor unit facing the user when in use is defined as the front side, and the opposite side is defined as the rear side. The left and right sides are distinguished by the direction the user faces when facing the outdoor unit.

[0084] The outdoor unit 100 of the air conditioner also includes an outdoor heat exchanger and an outdoor fan 13. The outdoor heat exchanger is located inside the casing 1 and installed inside the outdoor air inlet 11, and is used to exchange heat with the air entering the housing cavity of the casing 1. The outdoor fan 13 is located inside the casing 1 and faces the outdoor air outlet 12. The outdoor fan 13 is installed between the outdoor heat exchanger and the outdoor air outlet 12. Under the action of the outdoor fan 13, outdoor air enters the casing 1 through the outdoor air inlet 11. The outdoor air exchanges heat with the outdoor heat exchanger inside the casing 1. The outdoor air after heat exchange is discharged from the casing 1 through the outdoor air outlet 12 under the drive of the outdoor fan 13.

[0085] The outdoor unit 100 of the air conditioner also includes a compressor, which is located inside the casing cavity. The compressor compresses the refrigerant gas into a high-temperature, high-pressure state and discharges the compressed refrigerant gas, which flows into the condenser. The condenser condenses the compressed, high-temperature, high-pressure gaseous refrigerant into liquid refrigerant, and the heat is released to the surrounding environment through the condensation process.

[0086] The outdoor unit 100 of the air conditioner also includes a frequency converter, which is located inside the cavity of the housing 1 and connected to the compressor. The frequency converter controls and adjusts the compressor speed to maintain it at the optimal speed, thereby achieving a more efficient cooling or heating effect. In this embodiment, the frequency converter is an AC-DC-AC type frequency converter, such as... Figure 3 The core circuit shown encompasses a bridgeless PFC circuit, a DC filter circuit, an inverter circuit, and a control circuit. The core function of the bridgeless PFC circuit is to efficiently rectify the mains power supply, converting AC to DC, and providing a stable DC power supply for the inverter circuit. The DC filter circuit, implemented using parallel large-capacity aluminum electrolytic capacitors, is an energy-consuming circuit. The inverter circuit converts DC to AC.

[0087] like Figure 4 As shown, the input terminal of the bridgeless PFC is connected to the AC input power supply, and the output terminal is connected in parallel with a DC filter capacitor C1. The DC filter capacitor C1 is connected to the inverter circuit at the back end, and the output of the inverter circuit controls the load motor.

[0088] A bridgeless PFC circuit consists of two main parts: the main power circuit and the power factor correction circuit, such as... Figure 5 The main power circuit includes an inductor L1, a first bridge arm, and a second bridge arm. The first bridge arm includes two diodes connected in series, namely a rectifier diode D1 and a first body diode, with the anode of the rectifier diode D1 connected to the cathode of the first body diode. The second bridge arm includes two diodes connected in series, namely a rectifier diode D2 and a second body diode, with the anode of the rectifier diode D2 connected to the cathode of the second body diode.

[0089] One end of inductor L1 is connected to the live wire of the AC input power supply, and the other end is connected to the common connection point of rectifier diode D1 and the first body diode. The cathodes of rectifier diode D1 and rectifier diode D2 are connected to the positive terminal of the DC filter circuit, and the anodes of the first body diode and the second body diode are connected to the negative terminal of the DC filter circuit.

[0090] like Figure 6 The power factor correction circuit includes a first power switch Q1, a second power switch Q2, a sampling resistor R1, a comparator circuit, and a driver circuit. The first power switch Q1 is connected in parallel across the first body diode, with its collector connected to the cathode of the first body diode and its emitter connected to the anode of the first body diode. The second power switch Q2 is connected in parallel across the second body diode, with its collector connected to the cathode of the second body diode and its emitter connected to the anode of the first body diode. The gates of both the first power switch Q1 and the second power switch Q2 are connected to the driver circuit.

[0091] One end of the sampling resistor R1 is connected to the emitter of the first power switch Q1, and the other end is connected to the emitter of the second power switch Q2.

[0092] The comparator circuit has its input terminals connected to both ends of the sampling resistor R1;

[0093] The driving circuit has its input terminal connected to the output terminal of the comparator circuit, and its output terminal connected to the gate of the first power switch and the gate of the second power switch, controlling the on / off state of the first power switch and the second power switch.

[0094] Based on the above structure, during the positive half-cycle of the AC input voltage, since the voltage across the first power switch Q1 is positive and the voltage across the second power switch Q2 is negative, the first power switch Q1 is turned on, the second power switch Q2 is not activated, and the first body diode is turned off. Therefore, the current flow path during the positive half-cycle of the AC voltage is as follows: starting from the live wire L terminal of the AC input power supply, through inductor L1, the first power switch Q1, sampling resistor R1, and the second body diode, returning to the neutral wire N terminal of the AC input power supply. During this period, inductor L1 is short-circuited and charged. The comparator circuit collects the voltage signal across the sampling resistor R1 for judgment. When the current flowing through the sampling resistor R1 exceeds the current threshold, the comparator circuit determines that the voltage across the sampling resistor R1 exceeds the set voltage threshold and outputs a corresponding fault logic level. The drive circuit controls the first power switch Q1 to turn off according to the fault logic level output by the comparator circuit, entering the freewheeling process, thereby avoiding damage to the first power switch due to excessive current.

[0095] During the off-state of the first power switch Q1, the current flow path is as follows: starting from the live wire (L) of the AC input power supply, passing through inductor L1, rectifier diode D1, and the second body diode, returning to the neutral wire (N) of the AC input power supply. At this time, the current does not pass through the sampling resistor, and the inductor releases energy to the subsequent stages.

[0096] During the negative half-cycle of the AC voltage, since the voltage across the first power switch Q1 is negative and the voltage across the second power switch Q2 is positive, the first power switch Q1 is inactive, the second power switch Q2 is on, and the second body diode is off. Therefore, the current flow path is as follows: starting from the neutral (N) terminal of the AC input power supply, through the second power switch Q2, sampling resistor R1, the first body diode, and inductor L1, returning to the live (L) terminal of the AC input power supply. During this period, the inductor charges, and the comparator circuit collects the voltage signal across the sampling resistor R1 for judgment. When the current flowing through the sampling resistor R1 exceeds the current threshold, the comparator circuit determines that the voltage across the sampling resistor R1 exceeds the set voltage threshold and outputs a corresponding fault logic level. The drive circuit controls the second power switch Q2 to turn off based on the fault logic level output by the comparator circuit, entering the freewheeling process, thereby avoiding damage to the power switches from excessive current.

[0097] During the off-state of the second power switch Q2, the current flow path is as follows: starting from the neutral (N) terminal of the AC input power supply, passing through the rectifier diode D2, the energy storage capacitor C1, the sampling resistor R1, the first body diode, and the inductor L1, returning to the live (L) terminal of the AC input power supply. During this period, the inductor releases energy to the downstream load.

[0098] This application uses a single sampling resistor and comparator circuit structure to realize the overcurrent protection function of the circuit, which not only improves the overcurrent response speed of the circuit, but also reduces the number of components, realizes overcurrent detection at low cost, thereby reducing the overall cost and enhancing the market competitiveness of the whole machine.

[0099] like Figure 7 In some embodiments, to achieve monitoring of the main power circuit current throughout the entire AC input power cycle, the comparator circuit is further designed, including two comparator circuits. The comparator circuit includes a first comparator circuit and a second comparator circuit, wherein...

[0100] The first comparator circuit has its non-inverting input connected to the first terminal of the sampling resistor R1, its inverting input connected to the second terminal of the sampling resistor R2, and its output connected to the input terminal of the drive circuit, used to monitor the forward current.

[0101] The second comparator circuit has its inverting input connected to the first terminal of the sampling resistor R1, its non-inverting input connected to the second terminal of the sampling resistor R1, and its output connected to the input of the drive circuit, used to monitor the reverse current.

[0102] When the main power positive current flows through the sampling resistor R1, the first comparator circuit collects the voltage difference across the sampling resistor R1 and compares it with the set threshold voltage. As the current gradually increases, when the current exceeds the threshold current, that is, when the voltage across the sampling resistor exceeds the threshold voltage, the first comparator outputs the corresponding fault logic level. The drive circuit receives the fault logic level output by the first comparator and controls the first power switch to turn off, so as to avoid the power switch being damaged by excessive current.

[0103] When the main power reverse current flows through the sampling resistor R1, the second comparator circuit collects the voltage difference across the sampling resistor R1 and compares it with the set threshold voltage. As the current gradually increases, when the current exceeds the threshold current, that is, when the voltage across the sampling resistor exceeds the threshold voltage, the second comparator outputs the corresponding fault logic level. The drive circuit receives the fault logic level output by the second comparator and controls the second power switch to turn off, so as to avoid the power switch being damaged by excessive current.

[0104] In some embodiments of this application, the first comparator circuit includes the following components for acquiring the positive voltage signal flowing through the sampling resistor:

[0105] The first voltage limiting resistor R3 is connected at one end to the first end of the sampling resistor;

[0106] The second voltage limiting resistor R4 is connected at one end to the second end of the sampling resistor;

[0107] The first comparator N1 has its non-inverting input connected to the other end of the first voltage-limiting resistor R3, its inverting input connected to the other end of the sampling second voltage-limiting resistor R4, and its output connected to the input of the drive circuit.

[0108] When a forward current flows through the sampling resistor, the first comparator N1 operates, acquiring the voltage signals across the sampling resistor R1 to form the non-inverting input voltage Vn+ and the inverting input voltage Vn-. The operating logic of the first comparator N1 is as follows:

[0109] When Vn+>Vn-, the output voltage is VCC;

[0110] When Vn+>Vn-, the output voltage is zero.

[0111] Since resistors impede current flow, voltage limiting resistors R3 and R4 can prevent the comparator from being affected by excessive current.

[0112] In some embodiments of this application, in order to achieve the range setting of the threshold voltage in the comparator circuit, the first comparator circuit further includes a first hysteresis adjustment resistor R6. The first hysteresis adjustment resistor R6 is connected between the output terminal and the non-inverting input terminal of the first comparator N1 to form a positive feedback network, so that the circuit has hysteresis characteristics.

[0113] The first comparator N1 detects the forward current of the main power circuit. When the first comparator N1 outputs a high level, the first hysteresis adjustment resistor R6 feeds a portion of the output voltage back to the non-inverting input of the first comparator N1, raising the voltage at the non-inverting input and forming the first upper threshold voltage. When the first comparator N1 outputs a low level, the first hysteresis adjustment resistor R6 feeds a portion of the output voltage back to the non-inverting input of the first comparator N1, lowering the voltage at the non-inverting input and forming the first lower threshold voltage. This hysteresis characteristic of the circuit means that when the input voltage reaches near the threshold voltage, the comparator output level does not immediately flip, but only flips when the input voltage changes further. This suppresses frequent jumps and oscillations at the output, enhances the comparator's anti-interference capability, avoids external changes in the comparator output voltage affecting the input voltage, and improves the stability of the comparator circuit.

[0114] In some embodiments of this application, in order to ensure that the output of the first comparator N1 is a positive voltage, bias resistors are provided at the two input terminals of the first comparator. One end of the first bias resistor R2 is connected to the non-inverting input terminal and the other end is connected to the reference voltage VCC; one end of the second bias resistor R5 is connected to the inverting input terminal and the other end is connected to the reference voltage VCC.

[0115] After adding a bias resistor R2 to the non-inverting input, the voltage at the non-inverting input is divided into three parts:

[0116] The voltage divider between the voltage limiting resistor R3 and the bias resistor R2 at the power supply VCC;

[0117] The voltage divider between the voltage limiting resistor R2 and the bias resistor R3 at the first terminal of the sampling resistor R1;

[0118] The output voltage is fed back by the hysteresis regulating resistor R6.

[0119] After adding a bias resistor R5 to its inverting output terminal, the voltage at its inverting input terminal is divided into two parts:

[0120] The voltage divider between the voltage limiting resistor R4 and the bias resistor R5 at the power supply VCC;

[0121] The voltage divider formed by the voltage limiting resistor R4 and the bias resistor R5 at the second terminal of the sampling resistor R1.

[0122] The bias circuit formed by the bias resistor provides a reference voltage to the input of the first comparator N1, so that the output voltage remains at a positive potential regardless of whether the AC input power supply is in a positive or negative cycle.

[0123] In some embodiments, in order to achieve a stable output of the first comparator circuit, the first comparator circuit further includes a filter capacitor C2 located at the output terminal of the first comparator N1. The filter capacitor bypasses the high-frequency interference components in the output signal of the first comparator circuit to ground, allowing low-frequency components and useful signals to pass smoothly, thereby smoothing the output voltage and preventing voltage jitter from affecting the back-end control circuit.

[0124] In some embodiments, to ensure the stability of the comparator circuit, when both the first comparator N1 and the second comparator N2 have pull-up output capability, the first comparator circuit further includes a current-limiting resistor R7, one end of which is connected to the output terminal of the first comparator N1 and the other end of which is connected to the non-grounded terminal of the filter capacitor C2. Setting the current-limiting resistor R7 at the output terminal of the first comparator increases the total resistance value of the circuit and prevents a short circuit between the first comparator N1 and the second comparator N2.

[0125] In some embodiments of this application, the second comparator circuit includes the following components for acquiring the reverse current flowing through the sampling resistor:

[0126] The third voltage limiting resistor R9 is connected at one end to the second end of the sampling resistor;

[0127] The fourth voltage limiting resistor R10 is connected at one end to the first end of the sampling resistor;

[0128] The second comparator N2 has its non-inverting input connected to the other end of the third voltage limiting resistor R9, its inverting input connected to the other end of the fourth voltage limiting resistor R10, and its output connected to the input of the drive circuit.

[0129] When reverse current flows through the sampling resistor, the second comparator N1 operates, acquiring the voltage signals across the sampling resistor R1 to form the non-inverting input voltage Vn+ and the inverting input voltage Vn-. The operating logic of the first comparator N1 is as follows:

[0130] When Vn+>Vn-, the output voltage is VCC;

[0131] When Vn+>Vn-, the output voltage is zero.

[0132] Since resistors impede current flow, voltage limiting resistors R9 and R10 can prevent the comparator from being affected by excessive current.

[0133] In some embodiments of this application, in order to achieve the range setting of the threshold voltage in the comparator circuit, the second comparator circuit further includes a second hysteresis adjustment resistor R13. The first hysteresis adjustment resistor R13 is connected between the output terminal and the non-inverting input terminal of the second comparator N2 to form a positive feedback network, so that the circuit has hysteresis characteristics.

[0134] The second comparator N2 detects the reverse current of the main power circuit. When the second comparator N2 outputs a high level, the second hysteresis adjustment resistor R13 feeds a portion of the output voltage back to the non-inverting input of the second comparator N2, raising the voltage at the non-inverting input and forming the second upper threshold voltage. When the second comparator N2 outputs a low level, the second hysteresis adjustment resistor R13 feeds a portion of the output voltage back to the non-inverting input of the second comparator N2, lowering the voltage at the non-inverting input and forming the second lower threshold voltage. This hysteresis characteristic of the circuit means that when the input voltage reaches near the threshold voltage, the comparator output level does not immediately flip, but only when the input voltage changes further. This suppresses frequent jumps and oscillations at the output, enhances the comparator's anti-interference capability, avoids external changes in the comparator output voltage affecting the input voltage, and improves the stability of the comparator circuit.

[0135] In some embodiments of this application, in order to ensure that the output of the second comparator N2 is a positive voltage, bias resistors are provided at the two input terminals of the second comparator. One end of the third bias resistor R11 is connected to the non-inverting input terminal and the other end is connected to the reference voltage VCC; one end of the fourth bias resistor R12 is connected to the inverting input terminal and the other end is connected to the reference voltage VCC.

[0136] After adding a bias resistor R11 to the non-inverting input, the voltage at the non-inverting input is divided into three parts:

[0137] The voltage divider between the voltage limiting resistor R9 and the bias resistor R11 at the power supply VCC;

[0138] The voltage divider between the voltage limiting resistor R9 and the bias resistor R11 at the first terminal of the sampling resistor R1;

[0139] The output voltage is fed back by the hysteresis regulating resistor R13.

[0140] After adding a bias resistor R12 to its inverting output terminal, the voltage at its inverting input terminal is divided into two parts:

[0141] The voltage divider between the voltage limiting resistor R10 and the bias resistor R12 at the power supply VCC;

[0142] The voltage divider formed by the voltage limiting resistor R10 and the bias resistor R12 at the second end of the sampling resistor R1.

[0143] The bias circuit formed by the bias resistor provides a reference voltage to the input of the second comparator N2, so that the output voltage remains at a positive potential regardless of whether the AC input power supply is in a positive or negative cycle.

[0144] This utility model also provides an outdoor unit for an air conditioner, which will be described below with reference to the accompanying drawings.

[0145] refer to Figures 1-2 The outdoor unit 100 of the air conditioner includes a housing 1, which is installed outdoors and forms the overall appearance of the outdoor unit. The housing 1 also defines a storage space inside the housing for installing and fixing the various components of the outdoor unit.

[0146] Further reference Figures 1-2 The casing 1 also defines an outdoor air inlet 11 and an outdoor air outlet 12, both of which are connected to the housing space. The outdoor air inlet 11 serves as the inlet for external air to flow into the casing, while the outdoor air outlet 12 serves as the outlet for heat-exchanged air to flow out of the casing 1. Indoor air from outside the casing 1 enters the casing 1 through the indoor air inlet 11 and is finally discharged into the room through the outdoor air outlet 12.

[0147] Specifically, the outdoor air inlet 11 can be located on the rear side of the housing 1, and the outdoor air outlet 12 is located on the front side of the housing 1.

[0148] It should be noted that the directions described in the text are based on the direction the user faces when facing the outdoor unit of the air conditioner. Specifically, the side of the outdoor unit facing the user when in use is defined as the front side, and the opposite side is defined as the rear side. The left and right sides are distinguished by the direction the user faces when facing the outdoor unit.

[0149] The outdoor unit 100 of the air conditioner also includes an outdoor heat exchanger and an outdoor fan 13. The outdoor heat exchanger is located inside the casing 1 and installed inside the outdoor air inlet 11, and is used to exchange heat with the air entering the housing cavity of the casing 1. The outdoor fan 13 is located inside the casing 1 and faces the outdoor air outlet 12. The outdoor fan 13 is installed between the outdoor heat exchanger and the outdoor air outlet 12. Under the action of the outdoor fan 13, outdoor air enters the casing 1 through the outdoor air inlet 11. The outdoor air exchanges heat with the outdoor heat exchanger inside the casing 1. The outdoor air after heat exchange is discharged from the casing 1 through the outdoor air outlet 12 under the drive of the outdoor fan 13.

[0150] The outdoor unit 100 of the air conditioner also includes a compressor, which is located inside the casing cavity. The compressor compresses the refrigerant gas into a high-temperature, high-pressure state and discharges the compressed refrigerant gas, which flows into the condenser. The condenser condenses the compressed, high-temperature, high-pressure gaseous refrigerant into liquid refrigerant, and the heat is released to the surrounding environment through the condensation process.

[0151] The outdoor unit 100 of the air conditioner also includes a frequency converter, which is located inside the cavity of the housing 1 and connected to the compressor. The frequency converter controls and adjusts the compressor speed to maintain it at the optimal speed, thereby achieving a more efficient cooling or heating effect. In this embodiment, the frequency converter is an AC-DC-AC type frequency converter, such as... Figure 3 The core circuit shown encompasses a bridgeless PFC circuit, a DC filter circuit, an inverter circuit, and a control circuit. The core function of the bridgeless PFC circuit is to efficiently rectify the mains power supply, converting AC to DC, and providing a stable DC power supply for the inverter circuit. The DC filter circuit, implemented using parallel large-capacity aluminum electrolytic capacitors, is an energy-consuming circuit. The inverter circuit converts DC to AC.

[0152] like Figure 4 As shown, the input terminal of the bridgeless PFC is connected to the AC input power supply, and the output terminal is connected in parallel with a DC filter capacitor C1. The DC filter capacitor C1 is connected to the inverter circuit at the back end, and the output of the inverter circuit controls the load motor.

[0153] A bridgeless PFC circuit consists of two main parts: the main power circuit and the power factor correction circuit, such as... Figure 5 The main power circuit includes an inductor L1, a first bridge arm, and a second bridge arm. The first bridge arm includes two diodes connected in series, namely a rectifier diode D1 and a first body diode, with the anode of the rectifier diode D1 connected to the cathode of the first body diode. The second bridge arm includes two diodes connected in series, namely a rectifier diode D2 and a second body diode, with the anode of the rectifier diode D2 connected to the cathode of the second body diode.

[0154] One end of inductor L1 is connected to the live wire of the AC input power supply, and the other end is connected to the common connection point of rectifier diode D1 and the first body diode. The cathodes of rectifier diode D1 and rectifier diode D2 are connected to the positive terminal of the DC filter circuit, and the anodes of the first body diode and the second body diode are connected to the negative terminal of the DC filter circuit.

[0155] like Figure 6 The power factor correction circuit includes switching transistors, a sampling resistor R1, a comparator circuit, and a driver circuit. The switching transistors include a first power switch Q1 and a second power switch Q2. The first power switch Q1 is connected in parallel across a first body diode, with its collector connected to the cathode of the first body diode and its emitter connected to the anode of the first body diode. The second power switch Q2 is connected in parallel across a second body diode, with its collector connected to the cathode of the second body diode and its emitter connected to the anode of the first body diode. The gates of both the first power switch Q1 and the second power switch Q2 are connected to the driver circuit.

[0156] One end of the sampling resistor R1 is connected to the emitter of the first power switch Q1, and the other end is connected to the emitter of the second power switch Q2.

[0157] Comparison circuit: Its input terminal is connected to both ends of the sampling resistor;

[0158] AC sampling circuit: Connected to an AC power supply to sample the voltage of the AC power supply;

[0159] Control chip: Its input terminal is connected to the output terminal of the comparator circuit and the output terminal of the AC sampling circuit;

[0160] The driving circuit has its input terminal connected to the output terminal of the comparator circuit and the output terminal of the control chip, which is connected to the switching transistor to control the on / off state of the first power switching transistor and the second power switching transistor.

[0161] Based on the above structure, after the bridgeless PFC circuit is connected to the AC input power supply, the control chip first receives the voltage signal collected by the AC voltage sampling circuit and determines the zero crossing point and positive and negative half-cycle polarity of the AC voltage.

[0162] During the positive half-cycle of the AC input voltage, since the voltage across the first power switch Q1 is positive and the voltage across the second power switch Q2 is negative, the first power switch Q1 is turned on, the second power switch Q2 is not activated, and the first body diode is turned off. Therefore, the current flow path during the positive half-cycle of the AC voltage is as follows: starting from the live wire L terminal of the AC input power supply, through inductor L1, the first power switch Q1, sampling resistor R1, and the second body diode, it returns to the neutral wire N terminal of the AC input power supply. During this period, inductor L1 is short-circuited and charged until the first power switch Q1 is turned off under control, entering the freewheeling process.

[0163] During the off-state of the first power switch Q1, the current flow path is as follows: starting from the live wire (L) of the AC input power supply, passing through inductor L1, rectifier diode D1, and the second body diode, returning to the neutral wire (N) of the AC input power supply. At this time, the current does not pass through the sampling resistor, and the inductor releases energy to the subsequent stages.

[0164] In this way, the control chip continuously controls the first power switch Q1 to turn on and off during the positive half-cycle of the AC voltage, thereby continuously controlling the charging and discharging of the inductor until the positive half-cycle of the AC voltage ends and the negative half-cycle of the AC voltage begins.

[0165] During the negative half-cycle of the AC voltage, since the voltage across the first power switch Q1 is negative and the voltage across the second power switch Q2 is positive, the first power switch Q1 is not activated, the second power switch Q2 is activated, and the second body diode is deactivated. Therefore, the current flow path is as follows: starting from the neutral (N) terminal of the AC input power supply, passing through the second power switch Q2, the sampling resistor R1, the first body diode, and the inductor L1, returning to the live (L) terminal of the AC input power supply. During this period, the inductor charges until the second power switch Q2 is turned off, entering the freewheeling process.

[0166] During the off-state of the second power switch Q2, the current flow path is as follows: starting from the neutral (N) terminal of the AC input power supply, passing through the rectifier diode D2, the energy storage capacitor C1, the sampling resistor R1, the first body diode, and the inductor L1, returning to the live (L) terminal of the AC input power supply. During this period, the inductor releases energy to the downstream load.

[0167] In this way, the control chip continuously controls the second power switch Q2 to turn on and off during the negative half-cycle of the AC voltage, thereby continuously controlling the charging and discharging of the inductor L1 until the negative half-cycle of the AC voltage ends and the positive half-cycle of the AC voltage is entered again.

[0168] The control chip effectively adjusts the phase difference between the AC power supply and the main power circuit current by controlling the power switching transistor, thereby synchronizing the AC power supply and the main power circuit current, improving the energy conversion efficiency of the frequency converter, and enabling the whole machine to achieve a higher energy efficiency standard.

[0169] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be covered. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An air conditioner outdoor unit characterized by comprising: include: Shell: forms the shell cavity; Compressor: disposed within the housing cavity; Inverter: Located within the housing cavity and connected to the compressor, used to regulate the operating frequency of the compressor; the inverter includes a bridgeless PFC circuit; the bridgeless PFC circuit includes: Main power circuit: It consists of a first bridge arm and a second bridge arm connected in parallel, and each bridge arm includes two diodes connected in series; The power factor correction circuit includes: First power switch: connected in parallel across a diode in the first bridge arm; Second power switch: connected in parallel across a diode in the second bridge arm; Sampling resistor: disposed between the emitters of the first power switch and the second power switch; Comparison circuit: Its input terminal is connected to both ends of the sampling resistor; The driving circuit has its input terminal connected to the output terminal of the comparator circuit, and its output terminal connected to the first power switch and the second power switch, controlling the on / off state of the first power switch and the second power switch.

2. The air conditioner outdoor unit according to claim 1, characterized by The comparison circuit includes: The first comparator circuit has its non-inverting input connected to the first terminal of the sampling resistor, its inverting input connected to the second terminal of the sampling resistor, and its output connected to the input terminal of the driving circuit. The second comparator circuit has its inverting input connected to the first terminal of the sampling resistor, its non-inverting input connected to the second terminal of the sampling resistor, and its output connected to the input terminal of the driving circuit.

3. The air conditioner outdoor unit according to claim 2, characterized by The first comparator circuit includes: The first voltage limiting resistor has one end connected to the first end of the sampling resistor; The second voltage-limiting resistor is connected at one end to the second end of the sampling resistor; The first comparator has its non-inverting input connected to the other end of the first voltage-limiting resistor, its inverting input connected to the other end of the second voltage-limiting resistor, and its output connected to the input of the driving circuit.

4. The outdoor unit of the air conditioner according to claim 3, characterized in that, The first comparator circuit includes: The first hysteresis adjustment resistor has one end connected to the output terminal of the first comparator and the other end connected to the non-inverting input terminal of the first comparator.

5. The outdoor unit of the air conditioner according to claim 3, characterized in that, The first comparator circuit includes: The filter capacitor has one end connected to the output of the first comparator and the other end grounded.

6. The outdoor unit of the air conditioner according to claim 3, characterized in that, The first comparator circuit includes: The first bias resistor has one end connected to the non-inverting input of the first comparator and the other end connected to the reference voltage. The second bias resistor is connected at one end to the inverting input of the first comparator and at the other end to the reference voltage.

7. The outdoor unit of the air conditioner according to claim 2, characterized in that, The second comparator circuit includes: The third voltage-limiting resistor is connected at one end to the second end of the sampling resistor; The fourth voltage-limiting resistor is connected at one end to the first end of the sampling resistor; The second comparator has its non-inverting input connected to the other end of the third voltage-limiting resistor, its inverting input connected to the other end of the fourth voltage-limiting resistor, and its output connected to the input of the drive circuit.

8. The outdoor unit of the air conditioner according to claim 7, characterized in that, The second comparator circuit includes: The second hysteresis adjustment resistor is connected at one end to the output terminal of the second comparator and at the other end to the non-inverting input terminal of the second comparator.

9. The outdoor unit of the air conditioner according to claim 7, characterized in that, The second comparator circuit includes: The third bias resistor is connected at one end to the non-inverting input of the second comparator and at the other end to the reference voltage. The fourth bias resistor is connected at one end to the inverting input of the second comparator and at the other end to the reference voltage.

10. An outdoor unit for an air conditioner, characterized in that, include: Shell: forms the shell cavity; Compressor: disposed within the housing cavity; Inverter: disposed within the housing cavity and connected to the compressor, used to adjust the operating frequency of the compressor; the inverter includes a bridgeless PFC circuit; The input terminal of the bridgeless PFC circuit is connected to an AC power supply, including: Main power circuit: It consists of a first bridge arm and a second bridge arm connected in parallel, and each bridge arm includes two diodes connected in series; The power factor correction circuit includes: First power switch: connected in parallel across a diode in the first bridge arm; Second power switch: connected in parallel across a diode in the second bridge arm; Sampling resistor: disposed between the emitters of the first power switch and the second power switch; Comparison circuit: Its input terminal is connected to both ends of the sampling resistor; Sampling circuit: connected to AC power supply; Control chip: Its input terminal is connected to the output terminal of the comparator circuit and the output terminal of the sampling circuit; The driving circuit has its input terminal connected to the output terminal of the comparator circuit and the output terminal of the control chip, which is connected to the switching transistor to control the on / off state of the first power switching transistor and the second power switching transistor.

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