Air conditioner outdoor unit

Abstract

This utility model relates to the field of air conditioning technology, and more particularly to an outdoor unit for an air conditioner. The outdoor unit includes a housing, a compressor, and an inverter; the inverter includes a bridgeless PFC circuit, in which a current sampling circuit is designed. A sampling resistor is used to convert the current signal to a voltage signal, and the voltage signal is amplified by an operational conditioning circuit. The first operational conditioning circuit includes a first operational amplifier, a first feedback resistor, a first bias circuit, and a first filter circuit; the second operational conditioning circuit includes a second operational amplifier, a second feedback resistor, a second bias circuit, and a second filter circuit. This utility model simplifies the circuit structure, reduces power loss and cost, and is suitable for applications such as household inverter air conditioners that require efficient power factor correction circuits.

Description

Technical Field

[0001] This application relates to the field of air conditioning technology, and more particularly to an outdoor unit for an air conditioner. Background Technology

[0002] With increasingly stringent global energy efficiency requirements and growing environmental awareness, household inverter air conditioners, as high-energy-consuming appliances, are subject to increasingly stringent regulations regarding their energy efficiency. Power factor correction (PFC) technology, as a key technology for improving energy efficiency and reducing harmonic pollution, has become a standard feature of modern inverter air conditioner power systems. Among these, the bridgeless PFC topology has been widely used in the inverter air conditioner field due to its high efficiency.

[0003] Modern household inverter air conditioners typically employ a two-stage power system: the front stage is a bridgeless power factor correction (PFC) circuit to improve the power factor and convert AC to DC; the rear stage is a DC-DC converter or inverter to provide variable-frequency drive power to the compressor motor. Compared to traditional bridge PFC, the bridgeless PFC topology reduces diode conduction losses, theoretically achieving higher efficiency (approximately 1-2% improvement). For air conditioning equipment operating for extended periods, the cumulative energy savings are considerable.

[0004] However, while bridgeless power factor correction (PFC) circuits offer high efficiency, they also face the more complex challenge of current sensing. Current sensing is a fundamental guarantee for the operation of a power supply system, and its performance directly affects the overall reliability and safety. However, current current sensing methods suffer from technical bottlenecks such as complex circuit structures, difficulty in implementation, and high costs.

[0005] Therefore, how to simplify the circuit structure and implement the current detection function at low cost has become an urgent problem to be solved. Utility Model Content

[0006] This utility model solves at least to some extent one of the technical problems in the above-mentioned related technologies, and provides an outdoor unit for an air conditioner.

[0007] Embodiments of this disclosure provide an outdoor unit for an air conditioner, comprising:

[0008] Shell: forms the shell cavity;

[0009] Compressor: disposed within the housing cavity;

[0010] Inverter: disposed 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 comprising:

[0011] Main power circuit: includes a first bridge arm and a second bridge arm connected in parallel, and each bridge arm includes two diodes connected in series;

[0012] Energy storage capacitor: The positive terminal is connected to the first common connection point of the first bridge arm and the second bridge arm, and the negative terminal is connected to the second common connection point of the first bridge arm and the second bridge arm;

[0013] The power factor correction circuit includes:

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

[0015] The second power switch is connected in parallel across a diode in the second bridge arm.

[0016] First sampling resistor: disposed between the emitters of the first power switch and the second power switch;

[0017] First operational amplifier conditioning circuit: its input terminal is connected to both ends of the first sampling resistor;

[0018] The second sampling resistor is located between the negative terminal of the second power switch and the energy storage capacitor.

[0019] The second operational amplifier conditioning circuit has its input terminals connected to both ends of the second sampling resistor.

[0020] The control chip is connected to the output terminals of the first operational amplifier conditioning circuit and the second operational amplifier conditioning circuit, and its output terminal is connected to the first power switch and the second power switch.

[0021] The technical solution provided in this application brings at least the following beneficial effects: The air conditioner outdoor unit provided in this solution has a bridgeless PFC circuit in which sampling resistors are set simultaneously between the emitters of the first power switch and the second power switch, and between the emitter of the second power switch and the energy storage capacitor. By utilizing the proportional relationship between the resistor current and voltage, the detection of the current signal is converted into the detection of the voltage signal, and the voltage signal is amplified by the operational amplifier conditioning circuit. This current detection structure can ensure sufficient sampling window time, and the circuit structure is simple, easy to implement, and low in cost.

[0022] In other embodiments of this application, to achieve the amplification function of the sampled signal, the first operational amplifier conditioning circuit includes:

[0023] The first input resistor is connected at one end to the first end of the first sampling resistor;

[0024] The first operational amplifier has its inverting input connected to the other end of the first input resistor, its non-inverting input connected to the second end of the first sampling resistor, and its output connected to the control chip.

[0025] The first feedback resistor has one end connected to the inverting input terminal of the first operational amplifier and the other end connected to the output terminal of the operational amplifier.

[0026] The technical solution provided in this application brings at least the following beneficial effects: the input resistor, the operational amplifier, and the feedback resistor constitute the negative feedback network of the operational amplifier conditioning circuit, realizing the amplification function of the operational amplifier, and the amplified voltage signal is more easily processed by the control chip; at the same time, the feedback resistor feeds back a portion of the output voltage to the inverting input terminal, which is subtracted from the input signal at the inverting input terminal, thereby stabilizing the operating point of the circuit and reducing the influence of external factors such as temperature and power supply voltage.

[0027] In other embodiments of this application, to maintain equal impedances at the two input terminals of the operational amplifier, the first operational amplifier conditioning circuit includes:

[0028] The first matching resistor has one end connected to the second end of the first sampling resistor and the other end connected to the non-inverting input of the first operational amplifier.

[0029] The technical solution provided in this application offers at least the following advantages: The matching resistor at the non-inverting input ensures that the amplifier circuit maintains a balanced response to the two input signals, thereby improving the circuit's common-mode rejection and anti-interference capabilities. When the resistances at the two input terminals are equal, the influence of common-mode signals can be suppressed to the greatest extent, allowing the operational amplifier conditioning circuit to amplify the signal more accurately.

[0030] In other embodiments of this application, to ensure that the op-amp output voltage remains positive throughout the entire AC power cycle, the first op-amp conditioning circuit includes:

[0031] The first bias resistor has one end connected to the non-inverting input terminal of the first operational amplifier and the other end connected to the reference voltage.

[0032] The second bias resistor has one end connected to the non-inverting input of the first operational amplifier and the other end grounded.

[0033] The technical solution provided in this application has at least the following beneficial effects: the bias circuit composed of the first bias resistor and the second bias resistor provides a stable DC bias voltage for the op-amp. This design method is simple and effective, and can ensure that the op-amp can maintain stable performance under different operating conditions and ensure that the output voltage of the op-amp remains positive.

[0034] In other embodiments of this application, in order to stabilize the op-amp output signal, the first op-amp conditioning circuit includes:

[0035] The first filter resistor has its first end connected to the output terminal of the first operational amplifier and its second end connected to the control chip.

[0036] The first filter capacitor has one end connected to the second end of the filter resistor, and the other end grounded.

[0037] The technical solution provided in this application brings at least the following beneficial effects: the RC filter circuit composed of filter resistor and filter capacitor realizes the filtering function of the circuit. When the signal at the output terminal of the operational amplifier passes through the RC filter circuit, the high frequency component is bypassed to ground by the filter capacitor, while the low frequency or useful signal passes through smoothly, thereby smoothing the output voltage at the output terminal of the operational amplifier and avoiding the adverse effects of voltage jitter on the back-end control chip.

[0038] In other embodiments of this application, to achieve the amplification function of the sampled signal, the second operational amplifier conditioning circuit includes:

[0039] The second input resistor is connected at one end to the second end of the second sampling resistor;

[0040] The second operational amplifier has its inverting input connected to the other end of the second input resistor, its non-inverting input connected to the first end of the second sampling resistor, and its output connected to the control chip.

[0041] The second feedback resistor has one end connected to the inverting input terminal of the second operational amplifier and the other end connected to the output terminal of the second operational amplifier.

[0042] The technical solution provided in this application brings at least the following beneficial effects: the input resistor, the operational amplifier, and the feedback resistor constitute the negative feedback network of the operational amplifier conditioning circuit, realizing the amplification function of the operational amplifier, and the amplified voltage signal is more easily processed by the control chip; at the same time, the feedback resistor feeds back a portion of the output voltage to the inverting input terminal, which is subtracted from the input signal at the inverting input terminal, thereby stabilizing the operating point of the circuit and reducing the influence of external factors such as temperature and power supply voltage.

[0043] In other embodiments of this application, to maintain equal impedances at the two input terminals of the operational amplifier, the second operational amplifier conditioning circuit includes:

[0044] The second matching resistor has one end connected to the first end of the second sampling resistor and the other end connected to the non-inverting input of the second operational amplifier.

[0045] The technical solution provided in this application offers at least the following advantages: The matching resistor at the non-inverting input ensures that the amplifier circuit maintains a balanced response to the two input signals, thereby improving the circuit's common-mode rejection and anti-interference capabilities. When the resistances at the two input terminals are equal, the influence of common-mode signals can be suppressed to the greatest extent, allowing the operational amplifier conditioning circuit to amplify the signal more accurately.

[0046] In other embodiments of this application, to ensure that the op-amp output voltage remains positive throughout the entire AC power cycle, the second op-amp conditioning circuit includes:

[0047] The third bias resistor is connected at one end to the non-inverting input of the second op-amp and at the other end to the reference voltage.

[0048] The fourth bias resistor has one end connected to the non-inverting input of the second operational amplifier and the other end grounded.

[0049] The technical solution provided in this application has at least the following beneficial effects: the bias circuit composed of the third bias resistor and the fourth bias resistor provides a stable DC bias voltage for the op-amp. This design method is simple and effective, and can ensure that the op-amp can maintain stable performance under different operating conditions and ensure that the output voltage of the op-amp remains positive.

[0050] In other embodiments of this application, in order to stabilize the op-amp output signal, the second op-amp conditioning circuit includes:

[0051] The second filter resistor has its first end connected to the output terminal of the second operational amplifier and its second end connected to the control chip.

[0052] The second filter capacitor has one end connected to the second terminal of the second filter resistor, and the other end grounded.

[0053] The technical solution provided in this application brings at least the following beneficial effects: the RC filter circuit composed of filter resistor and filter capacitor realizes the filtering function of the circuit. When the signal at the output terminal of the operational amplifier passes through the RC filter circuit, the high frequency component is bypassed to ground by the filter capacitor, while the low frequency or useful signal passes through smoothly, thereby smoothing the output voltage at the output terminal of the operational amplifier and avoiding the adverse effects of voltage jitter on the back-end control chip.

[0054] This utility model also provides an outdoor unit for an air conditioner, comprising:

[0055] Shell: forms the shell cavity;

[0056] Compressor: disposed within the housing cavity;

[0057] Inverter: disposed 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 comprising:

[0058] Main power circuit: includes a first bridge arm and a second bridge arm connected in parallel, each bridge arm including two diodes connected in series;

[0059] Energy storage capacitor: The positive terminal is connected to the first common connection point of the first bridge arm and the second bridge arm, and the negative terminal is connected to the second common connection point of the first bridge arm and the second bridge arm;

[0060] The power factor correction circuit includes:

[0061] First power switch: connected in parallel across a diode in the first bridge arm;

[0062] Second power switch: connected in parallel across a diode in the second bridge arm;

[0063] Sampling resistor: disposed between the emitter of the second power switch and the energy storage capacitor;

[0064] Operational amplifier conditioning circuit: Its input terminal is connected to both ends of the sampling resistor;

[0065] The control chip is connected to the output terminal of the operational amplifier conditioning circuit, and its output terminal is connected to the first power switch and the second power switch.

[0066] The technical solution provided in this application brings at least the following beneficial effects: The outdoor unit provided in this solution has a bridgeless PFC circuit in which a sampling resistor is set between the second power switch and the energy storage capacitor. By utilizing the proportional relationship between the resistor current and voltage, the detection of the current signal is converted into the detection of the voltage signal. The voltage signal is then amplified by the operational amplifier conditioning circuit. This current detection structure is not only simple and easy to implement, but also has a low cost.

[0067] Compared with the prior art, this utility model sets a sampling resistor in the main power circuit and uses the ratio of resistor current to voltage to detect the current flowing through the sampling resistor by detecting the voltage signal across the sampling resistor. Its structure is simple and easy to implement, and it has fewer components and lower cost, which greatly reduces the current sampling cost of the bridgeless PFC circuit and effectively improves the market competitiveness of the whole machine.

[0068] 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

[0069] 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.

[0070] Figure 1 , Figure 2 This is a three-dimensional structural view of the outdoor air conditioner unit in the embodiment;

[0071] Figure 3This is a schematic diagram of the logic circuit of the frequency converter;

[0072] Figure 4 This is a schematic diagram of the bridgeless PFC circuit in Embodiment 1;

[0073] Figure 5 This is a timing diagram of current sampling in Example 1;

[0074] Figure 6 This is a schematic diagram of the bridgeless PFC circuit in Embodiment 2;

[0075] Figure 7 This is the current sampling timing diagram for Example 2;

[0076] Figure 8 This is a schematic diagram of the bridgeless PFC circuit in Embodiment 3;

[0077] Figure 9 This is the current sampling timing diagram for Example 3. Detailed Implementation

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] In the following text, specific embodiments of this application will be described in detail with reference to the accompanying drawings.

[0084] 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 an accommodating space inside the housing for installing and fixing various components of the outdoor unit.

[0085] 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 outside the casing 1 enters the casing 1 through the outdoor air inlet 11 and is finally discharged into the room through the outdoor air outlet 12.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] The outdoor unit 100 of the air conditioner also includes an inverter, which is located in the internal cavity of the housing 1 and connected to the compressor. The inverter controls and adjusts the speed of the compressor to keep the compressor at the optimal speed, thereby achieving a more efficient cooling or heating effect.

[0091] 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 the energy-consuming circuit. The inverter circuit converts DC to AC.

[0092] like Figure 4As shown, the bridgeless PFC circuit consists of two main parts: a main power circuit and a power factor correction circuit. The main power circuit performs the rectification function of converting AC power to DC power. The output terminal of the main power circuit is connected to the subsequent load. The power factor correction circuit improves the power conversion efficiency of the main power circuit. The main power circuit includes a first bridge arm and a second bridge arm. The first bridge arm includes two diodes connected in series: a rectifier diode D1 and a first body diode. The anode of the rectifier diode D1 and the cathode of the first body diode are connected together. The second bridge arm includes two diodes connected in series: a rectifier diode D2 and a second body diode. The anode of the rectifier diode D2 and the cathode of the second body diode are connected together.

[0093] Inductor L1 is connected in series in the transmission circuit. One end 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.

[0094] To help the circuit release energy when needed, and further improve the circuit's efficiency and stability, the bridgeless PFC circuit is equipped with an energy storage capacitor C1. The positive terminal is connected to the common connection point of rectifier diodes D1 and D2, and the negative terminal is connected to the common connection point of the first body diode and the second body diode.

[0095] The power factor correction circuit includes a first power switch Q1, a second power switch Q2, a first sampling resistor R1, a first operational amplifier circuit, a second sampling resistor R1′, a second operational amplifier circuit, and a control chip. The first operational amplifier circuit and the first sampling resistor R1 constitute current sampling circuit 1, and the second operational amplifier circuit and the second sampling resistor R1′ constitute current sampling circuit 2.

[0096] 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.

[0097] The second power switch Q2 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.

[0098] In order to collect the current signal when the power switch is in the on state, one end of the first 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.

[0099] The first operational amplifier circuit includes a first input resistor R2, a first operational amplifier, and a first feedback resistor R4, which together form a negative feedback network to achieve the gain of the input signal. One end of the first input resistor R2 is connected to the first end of the sampling resistor R1, and the other end is connected to the inverting input terminal of the first operational amplifier. The first feedback resistor R4 is connected between the inverting input terminal and the output terminal of the first operational amplifier.

[0100] To maintain impedance matching at the input of the first op-amp, a first matching resistor R3 is connected to the non-inverting input of the first op-amp, and the other end of R3 is connected to the second end of the sampling resistor R1.

[0101] In this embodiment, the first input resistor and the first matching resistor have the same resistance value.

[0102] In order to keep the output potential of the first op-amp at a positive potential throughout the entire AC power cycle, the first op-amp circuit is equipped with a bias circuit, including a first bias resistor R6 and a second bias resistor R7. One end of the first bias resistor R6 is connected to the reference power supply VCC and the other end is connected to the non-inverting input of the first op-amp. One end of the second bias resistor R7 is connected to the non-inverting input of the first op-amp and the other end is grounded.

[0103] In this embodiment, the resistance value of the first feedback resistor R4 is equal to the resistance value of the bias circuit R6 and R7 connected in series.

[0104] In order to collect the current signal when the power switch is off, the second sampling resistor R1′ is connected at one end to the emitter of the second power switch Q2 and at the other end to the negative terminal of the energy storage capacitor C1.

[0105] The second operational amplifier circuit includes a second input resistor R2′, a second operational amplifier, and a second feedback resistor R4′, which together form a negative feedback network to achieve the gain of the input signal. One end of the second input resistor R2′ is connected to the first end of the second sampling resistor R1′, and the other end is connected to the inverting input terminal of the second operational amplifier. The second feedback resistor R4′ is connected between the inverting input terminal and the output terminal of the second operational amplifier.

[0106] To maintain impedance matching at the input of the second op-amp, a second matching resistor R3' is connected to the non-inverting input of the second op-amp, and the other end of the second matching resistor R3' is connected to the second end of the second sampling resistor R1'.

[0107] In this embodiment, the second input resistor and the second matching resistor have the same resistance value.

[0108] To maintain a positive output potential for the second op-amp throughout the entire AC power cycle, a bias circuit is provided in the second op-amp circuit, including a third bias resistor R6′ and a fourth bias resistor R7′. One end of the third bias resistor R6′ is connected to the reference power supply VCC, and the other end is connected to the non-inverting input of the second op-amp. One end of the fourth bias resistor R7′ is connected to the non-inverting input of the second op-amp, and the other end is grounded.

[0109] In this embodiment, the resistance value of the second feedback resistor R4 is equal to the resistance value of the bias resistors R6′ and R7′ connected in series.

[0110] The control chip is connected to the outputs of the first operational amplifier and the second operational amplifier. Its output is connected to the first power switch Q1 and the second power switch Q2, controlling the on / off state of the two power switches. In some embodiments, an AC voltage sampling circuit is also included, with its input connected to the AC input and its output connected to the control chip. The control chip combines the output signals of the first and second operational amplifiers and the AC voltage sampling circuit to control the on / off state of the two power switches.

[0111] In order to synchronize the current waveform with the voltage waveform of the AC input power supply to improve the power factor, this embodiment connects a voltage sampling circuit to the AC input power supply side to detect the voltage signal of the AC input power supply and send it to the control circuit.

[0112] 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, the 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 until the first power switch Q1 is controlled to turn off and enter the freewheeling process.

[0113] During the off-state of the first power switch Q1, the current flow path is as follows: starting from the live wire L terminal of the AC input power supply, through inductor L1, first rectifier diode D1, energy storage capacitor C1, second sampling resistor R1′, and second body diode, returning to the neutral wire N terminal of the AC input power supply. At this time, the inductor releases energy to the subsequent stage.

[0114] Thus, the control circuit 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.

[0115] 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.

[0116] 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 second 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.

[0117] Thus, the control circuit 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.

[0118] Based on the current path of the main power circuit above, the sampling logic of the current sampling circuit is as follows: Figure 5 As shown:

[0119] First, the control circuit determines the zero-crossing point and positive and negative half-cycle characteristics of the AC voltage based on the voltage signal of the AC input power supply.

[0120] During the positive half-cycle, the control circuit acquires the on-time of the first power switch Q1. When the on-time of the first power switch Q1 is greater than the sampling time limit threshold T1, the on-state of the first power switch Q1 is judged: if the first power switch Q1 is in the on state, the first operational amplifier samples the current flowing through the first sampling resistor R1; otherwise, no sampling is performed. When the on-time of the first power switch Q1 is less than the sampling time limit threshold T1, the on-state of the first power switch Q1 is judged: if the first power switch Q1 is in the off state, the second operational amplifier samples the current flowing through the second sampling resistor R1′; otherwise, no sampling is performed.

[0121] During the negative half-cycle, the control circuit obtains the conduction time of the first power switch Q2. When the conduction time of the second power switch Q2 is greater than the sampling time limit threshold T1, the control circuit continues to judge the conduction state of the second power switch Q2: if the second power switch Q2 is in the on state, the first operational amplifier samples the current flowing through the first sampling resistor R1; otherwise, no sampling is performed. If the conduction time of the second power switch Q2 is less than the sampling time limit threshold T1, the control circuit continues to judge the conduction state of the second power switch Q2: if the second power switch Q2 is in the off state, the second operational amplifier samples the current flowing through the second sampling resistor R1′; otherwise, no current sampling is performed.

[0122] After the timing judgment above, the negative feedback network in the first operational amplifier circuit and the negative feedback network in the second operational amplifier circuit amplify the input signal.

[0123] Let the current flowing through the sampling resistor R1 be I, the voltage at the current inlet be V1, and the voltage at the current outlet be V2, then

[0124] The bias voltage provided by the first bias circuit

[0125] The output voltage of the first op-amp

[0126] To stabilize the op-amp output signal, the first op-amp conditioning circuit includes an RC filter circuit, comprising a first filter resistor R5 and a first filter capacitor C2. The first end of the first filter resistor R5 is connected to the output terminal of the first op-amp and the control chip. One end of the first filter capacitor C2 is connected to the second end of the first filter resistor R5, and the other end is grounded. When the signal at the output terminal of the first op-amp passes through this RC filter circuit, the high-frequency components are bypassed to ground by the filter capacitor, while low-frequency or useful signals pass through smoothly, thereby smoothing the output voltage at the op-amp output terminal and avoiding the adverse effects of voltage jitter on the downstream control chip.

[0127] Let the current flowing through the sampling resistor R1′ be I′, the voltage at the current inflow terminal be V1, and the voltage at the current outflow terminal be V2, then

[0128]

[0129] The bias voltage provided by the second bias circuit

[0130] The voltage at the output of the second operational amplifier

[0131] To stabilize the op-amp output signal, the second op-amp conditioning circuit includes an RC filter circuit, comprising a second filter resistor R5′ and a second filter capacitor C2′. The first end of the second filter resistor R5′ is connected to the output terminal of the second op-amp and the control chip. One end of the second filter capacitor C2′ is connected to the second end of the second filter resistor R5′, and the other end is grounded. When the signal at the output terminal of the second op-amp passes through this RC filter circuit, high-frequency components are bypassed to ground by the filter capacitor, while low-frequency or useful signals pass through smoothly. This smooths the output voltage at the op-amp output terminal and avoids voltage jitter from adversely affecting the downstream control chip.

[0132] This utility model also provides an outdoor unit for an air conditioner. In the following, the specific embodiments of this application will be described in detail with reference to the accompanying drawings.

[0133] This embodiment references the bridgeless PFC circuit structure. Figure 6The bridgeless PFC circuit consists of two main parts: a main power circuit and a power factor correction circuit. The main power circuit performs the rectification function of converting AC to DC power, and its output is connected to the subsequent load. The power factor correction circuit improves the power conversion efficiency of the main power circuit. The main power circuit includes a first bridge arm, a second bridge arm, and an energy storage capacitor C1. The first bridge arm includes two diodes connected in series: a rectifier diode D1 and a first body diode, with the anode of rectifier diode D1 connected to the cathode of the first body diode. The second bridge arm includes two diodes connected in series: a rectifier diode D2 and a second body diode, with the anode of rectifier diode D2 connected to the cathode of the second body diode. The energy storage capacitor C1 is connected in parallel across the second bridge arm.

[0134] Inductor L1 is connected in series in the transmission circuit. One end 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 energy storage capacitor C1. The anodes of the first body diode and the second body diode are connected to the negative terminal of energy storage capacitor C1.

[0135] The power factor correction circuit includes a first power switch Q1, a second power switch Q2, a sampling resistor R1, an operational amplifier conditioning circuit, and a control chip. The operational conditioning circuit and the sampling resistor constitute the current sampling circuit.

[0136] 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 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.

[0137] One end of the sampling resistor R1 is connected to the emitter of the second power switch Q2, and the other end is connected to the negative terminal of the energy storage capacitor C1.

[0138] The operational amplifier circuit includes an input resistor R2, an operational amplifier, and a feedback resistor R4. These three components form a negative feedback network to achieve the gain of the input signal. One end of the input resistor R2 is connected to the first end of the sampling resistor R1, and the other end is connected to the inverting input terminal of the operational amplifier. The feedback resistor R4 is connected between the inverting input terminal and the output terminal of the operational amplifier.

[0139] To maintain impedance matching at the op-amp input, a matching resistor R3 is connected to the non-inverting input of the op-amp, and the other end of R3 is connected to the second end of the sampling resistor R1.

[0140] In this embodiment, the input resistor R2 and the matching resistor R3 have the same resistance value.

[0141] To maintain the operational amplifier output voltage at a positive level throughout the entire AC power cycle, the operational amplifier circuit is equipped with a bias circuit, including a first bias resistor R6 and a second bias resistor R7. One end of the first bias resistor R6 is connected to the reference power supply VCC, and the other end is connected to the non-inverting input terminal of the operational amplifier. One end of the second bias resistor R7 is connected to the non-inverting input terminal of the operational amplifier, and the other end is grounded.

[0142] In this embodiment, the resistance value of the feedback resistor R4 is equal to the resistance value of the bias resistors R6 and R7 connected in series.

[0143] The control chip is connected to the outputs of the first and second operational amplifiers, and its output is connected to the first power switch Q1 and the second power switch Q2, controlling the on / off state of the two power switches. In some embodiments, an AC voltage sampling circuit is also included, with its input connected to the AC input and its output connected to the control chip. The control chip combines the output signals of the operational amplifiers and the output signal of the AC voltage sampling circuit to control the on / off state of the two power switches.

[0144] In order to synchronize the current waveform with the voltage waveform of the AC input power supply to improve the power factor, this embodiment connects a voltage sampling circuit to the AC input power supply side to detect the voltage signal of the AC input power supply and send it to the control circuit.

[0145] 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, passing through inductor L1, the first power switch Q1, and the second body diode, and returning 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 controlled to turn off and enters the freewheeling process.

[0146] 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, through inductor L1, first rectifier diode D1, energy storage capacitor C1, sampling resistor R1, and second body diode, returning to the neutral wire (N) of the AC input power supply. At this time, the inductor releases energy to the next stage.

[0147] Thus, the control circuit 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.

[0148] 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 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.

[0149] 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 second 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.

[0150] Thus, the control circuit 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.

[0151] Based on the current path of the main power circuit above, the sampling logic of the current sampling circuit is as follows: Figure 7 As shown:

[0152] First, the control circuit determines the zero-crossing point and positive and negative half-cycle characteristics of the AC voltage based on the voltage signal of the AC input power supply.

[0153] During the positive half-cycle, determine the conduction state of the first power switch Q1: if the first power switch Q1 is turned off, then current sampling is performed; otherwise, current sampling is not performed.

[0154] When in the negative half-cycle, determine the conduction state of the second power switch Q2: if the second power switch Q2 is turned off, then current sampling is performed; otherwise, current sampling is not performed.

[0155] After the timing judgment above, the negative feedback network in the operational amplifier circuit amplifies the input signal;

[0156] Let the current flowing through the sampling resistor R1 be I, the voltage at the current inlet be V1, and the voltage at the current outlet be V2, then

[0157] The bias voltage provided by the bias circuit

[0158] op amp output voltage

[0159] To stabilize the op-amp output signal, the op-amp conditioning circuit includes an RC filter circuit, comprising a first filter resistor R5 and a first filter capacitor C2. The first end of the first filter resistor R5 is connected to the op-amp output terminal and the first end is connected to the control chip. One end of the first filter capacitor C2 is connected to the second end of the first filter resistor R5, and the other end is grounded. When the op-amp output signal passes through this RC filter circuit, high-frequency components are bypassed to ground by the filter capacitor, while low-frequency or useful signals pass through smoothly, thereby smoothing the output voltage of the op-amp output terminal and avoiding the adverse effects of voltage jitter on the downstream control chip.

[0160] In addition, this utility model also provides an outdoor unit for an air conditioner. In the following, the specific embodiments of this application will be described in detail with reference to the accompanying drawings.

[0161] The structure of the bridgeless PFC circuit in this embodiment is as follows: Figure 8 The bridgeless PFC circuit consists of two main parts: a main power circuit and a power factor correction circuit. The main power circuit performs the rectification function of converting AC to DC power, and its output is connected to the subsequent load. The power factor correction circuit improves the power conversion efficiency of the main power circuit. The main power circuit includes a first bridge arm, a second bridge arm, and an energy storage capacitor C1. The first bridge arm includes two diodes connected in series: a rectifier diode D1 and a first body diode, with the anode of rectifier diode D1 connected to the cathode of the first body diode. The second bridge arm includes two diodes connected in series: a rectifier diode D2 and a second body diode, with the anode of rectifier diode D2 connected to the cathode of the second body diode. The energy storage capacitor C1 is connected in parallel across the second bridge arm.

[0162] Inductor L1 is connected in series in the transmission circuit. One end 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 energy storage capacitor C1. The anodes of the first body diode and the second body diode are connected to the negative terminal of energy storage capacitor C1.

[0163] The power factor correction circuit includes a first power switch Q1, a second power switch Q2, a sampling resistor R1, an operational amplifier conditioning circuit, and a control chip. The switches are the first power switch Q1 and the 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.

[0164] 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;

[0165] The operational amplifier circuit includes an input resistor R2, an operational amplifier, and a feedback resistor R4. These three components form a negative feedback network to increase the input signal gain. One end of the input resistor R2 is connected to the first terminal of the sampling resistor R1, and the other end is connected to the inverting input terminal of the operational amplifier. The feedback resistor R4 is connected between the inverting input terminal and the output terminal of the operational amplifier. The operational conditioning circuit and the sampling resistor section constitute a current sampling circuit.

[0166] To maintain impedance matching at the op-amp input, a matching resistor R3 is connected to the non-inverting input of the op-amp, and the other end of R3 is connected to the second end of the sampling resistor R1.

[0167] In this embodiment, the input resistor R2 and the matching resistor R3 have the same resistance value.

[0168] To maintain the operational amplifier output voltage at a positive level throughout the entire AC power cycle, the operational amplifier circuit is equipped with a bias circuit, including a first bias resistor R6 and a second bias resistor R7. One end of the first bias resistor R6 is connected to the reference power supply VCC, and the other end is connected to the non-inverting input terminal of the operational amplifier. One end of the second bias resistor R7 is connected to the non-inverting input terminal of the operational amplifier, and the other end is grounded.

[0169] In this embodiment, the resistance value of the feedback resistor R4 is equal to the resistance value of the bias resistors R6 and R7 connected in series.

[0170] The control chip is connected to the outputs of the first and second operational amplifiers, and its output is connected to the first power switch Q1 and the second power switch Q2, controlling the on / off state of the two power switches. In some embodiments, an AC voltage sampling circuit is also included, with its input connected to the AC input and its output connected to the control chip. The control chip combines the output signals of the operational amplifiers and the output signal of the AC voltage sampling circuit to control the on / off state of the two power switches.

[0171] In order to synchronize the current waveform with the voltage waveform of the AC input power supply to improve the power factor, this embodiment connects a voltage sampling circuit to the AC input power supply side to detect the voltage signal of the AC input power supply and send it to the control circuit.

[0172] 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, the 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 until the first power switch Q1 is controlled to turn off and enter the freewheeling process.

[0173] 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, the first rectifier diode D1, the energy storage capacitor C1, and the second body diode, returning to the neutral wire (N) of the AC input power supply. At this time, the inductor releases energy to the next stage.

[0174] Thus, the control circuit 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.

[0175] 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.

[0176] 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 second 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.

[0177] Thus, the control circuit 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.

[0178] Based on the current path of the main power circuit above, the sampling logic of the current sampling circuit is as follows: Figure 9 As shown:

[0179] First, the control circuit determines the zero-crossing point and positive and negative half-cycle characteristics of the AC voltage based on the voltage signal of the AC input power supply.

[0180] During the positive half-cycle, determine the conduction state of the first power switch Q1: if the first power switch Q1 is on, perform current sampling; otherwise, do not perform current sampling.

[0181] When in the negative half-cycle, determine the conduction state of the second power switch Q2: if the second power switch Q2 is on, then current sampling is performed; otherwise, current sampling is not performed.

[0182] After the timing judgment above, the negative feedback network in the operational amplifier circuit amplifies the input signal;

[0183] Let the current flowing through the sampling resistor R1 be I, the voltage at the current inlet be V1, and the voltage at the current outlet be V2, then...

[0184]

[0185] The bias voltage provided by the bias circuit

[0186] op amp output voltage

[0187] To stabilize the op-amp output signal, the op-amp conditioning circuit includes an RC filter circuit, comprising a first filter resistor R5 and a first filter capacitor C2. The first end of the first filter resistor R5 is connected to the op-amp output terminal and the first end is connected to the control chip. One end of the first filter capacitor C2 is connected to the second end of the first filter resistor R5, and the other end is grounded. When the op-amp output signal passes through this RC filter circuit, high-frequency components are bypassed to ground by the filter capacitor, while low-frequency or useful signals pass through smoothly, thereby smoothing the output voltage of the op-amp output terminal and avoiding the adverse effects of voltage jitter on the downstream control chip.

[0188] 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: disposed 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 comprising: Main power circuit: includes a first bridge arm and a second bridge arm connected in parallel, and each bridge arm includes two diodes connected in series; Energy storage capacitor: The positive terminal is connected to the first common connection point of the first bridge arm and the second bridge arm, and the negative terminal is connected to the second common connection point of the first bridge arm and the second bridge arm; 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; First sampling resistor: disposed between the emitters of the first power switch and the second power switch; First operational amplifier conditioning circuit: its input terminal is connected to both ends of the first sampling resistor; The second sampling resistor is located between the emitter of the second power switch and the negative terminal of the energy storage capacitor. The second operational amplifier conditioning circuit has its input terminals connected to both ends of the second sampling resistor. Control chip: connected to the output terminals of the first operational amplifier conditioning circuit and the second operational amplifier conditioning circuit; its output terminal is connected to the first power switch and the second power switch.

2. The air conditioner outdoor unit according to claim 1, characterized by The first operational amplifier conditioning circuit includes: The first input resistor is connected at one end to the first end of the first sampling resistor; The first operational amplifier has its inverting input connected to the other end of the first input resistor, its non-inverting input connected to the second end of the first sampling resistor, and its output connected to the control chip. The first feedback resistor has one end connected to the inverting input terminal of the first operational amplifier and the other end connected to the output terminal of the operational amplifier.

3. The air conditioner outdoor unit according to claim 2, characterized by The first operational amplifier conditioning circuit includes: The first matching resistor has one end connected to the second end of the first sampling resistor and the other end connected to the non-inverting input of the first operational amplifier.

4. The air conditioner outdoor unit according to claim 3, characterized by The first operational amplifier conditioning circuit includes: The first bias resistor has one end connected to the non-inverting input terminal of the first operational amplifier and the other end connected to the reference voltage. The second bias resistor has one end connected to the non-inverting input of the first operational amplifier and the other end grounded.

5. The air conditioner outdoor unit according to claim 3, characterized by The first operational amplifier conditioning circuit includes: The first filter resistor has its first end connected to the output terminal of the first operational amplifier and its second end connected to the control chip. The second filter capacitor has one end connected to the second terminal of the filter resistor and the other end grounded.

6. The outdoor unit of the air conditioner according to claim 1, characterized in that, The second operational amplifier conditioning circuit includes: The second input resistor is connected at one end to the second end of the second sampling resistor; The second operational amplifier has its inverting input connected to the other end of the second input resistor, its non-inverting input connected to the first end of the second sampling resistor, and its output connected to the control chip. The second feedback resistor has one end connected to the inverting input terminal of the second operational amplifier and the other end connected to the output terminal of the second operational amplifier.

7. The outdoor unit of the air conditioner according to claim 6, characterized in that, The second operational amplifier conditioning circuit includes: The second matching resistor has one end connected to the first end of the second sampling resistor and the other end connected to the non-inverting input of the second operational amplifier.

8. The outdoor unit of the air conditioner according to claim 7, characterized in that, The second operational amplifier conditioning circuit includes: The third bias resistor is connected at one end to the non-inverting input of the second op-amp and at the other end to the reference voltage. The fourth bias resistor has one end connected to the non-inverting input of the second operational amplifier and the other end grounded.

9. The outdoor unit of the air conditioner according to claim 6, characterized in that, The second operational amplifier conditioning circuit includes: The second filter resistor has its first end connected to the output terminal of the second operational amplifier and its second end connected to the control chip. The second filter capacitor has one end connected to the second terminal of the second filter resistor, and the other end grounded.

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 regulate the operating frequency of the compressor; the inverter includes a bridgeless PFC circuit, the bridgeless PFC circuit comprising: The main power circuit includes a first bridge arm and a second bridge arm connected in parallel, and each bridge arm includes two diodes connected in series. Energy storage capacitor: The positive terminal is connected to the first common connection point of the first bridge arm and the second bridge arm, and the negative terminal is connected to the second common connection point of the first bridge arm and the second bridge arm; 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 emitter of the second power switch and the negative terminal of the energy storage capacitor; Operational amplifier conditioning circuit: Its input terminal is connected to both ends of the sampling resistor; Control chip: Connected to the output terminal of the operational amplifier conditioning circuit, and its output terminal is connected to the first power switch and the second power switch.

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