Conversion circuit, power supply circuit, fan and air conditioner

Abstract

The utility model provides a conversion circuit, a power supply circuit, a fan and an air conditioner, which can reduce the voltage of a high-voltage direct-current bus to a target voltage and provide a stable low-voltage power supply for a first frequency converter, so that the first frequency converter can select an I PM module and other electronic elements with low voltage class, and the hardware cost is remarkably reduced. Meanwhile, by reasonably distinguishing the voltage levels of the target load and the non-target load and only adopting the voltage reduction design for the target load (such as a fan), the high cost caused by the fact that the whole machine uses a high-voltage voltage level device is avoided, and the reduction of the overall hardware cost of the system is realized.

Description

Technical Field

[0001] The utility model relates to the technical field of air conditioners, and in particular to a conversion circuit, a power supply circuit, a fan and an air conditioner. Background Art

[0002] Three-phase inverter air conditioners are air conditioning systems that utilize three-phase power and inverter technology to adjust the compressor speed based on actual demand, achieving temperature control and energy efficiency. These systems are widely used in commercial and industrial sectors, providing stable and reliable environmental control.

[0003] In existing technology, three-phase variable-frequency air conditioners typically use a high-voltage DC bus (e.g., 540V) to directly power multiple inverter modules, including various loads such as compressors and fans. Due to the high DC bus voltage, these multiple inverter modules require high-voltage IPMs (Intelligent Power Modules) and corresponding high-voltage electronic components, significantly increasing hardware costs. Consequently, three-phase variable-frequency air conditioners present a technical problem of excessively high hardware costs. Summary of the Invention

[0004] The purpose of the present invention is to overcome the above technical deficiencies and provide a conversion circuit, a power supply circuit, a fan and an air conditioner to solve the technical problem of excessively high hardware cost in three-phase variable frequency air conditioner units in the related art.

[0005] In order to achieve the above technical purpose, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present invention provides a conversion circuit, the conversion circuit comprising at least:

[0007] A step-down module, wherein the positive input terminal of the step-down module is connected to the DC bus, the positive output terminal and the negative output terminal are connected to the first inverter, and the target voltage is provided to the first inverter. The negative input terminal and the negative output terminal of the step-down module are connected. The DC bus is used to provide a DC bus voltage to the second inverter. The first inverter is an inverter connected to the target load, and the second inverter is an inverter connected to the non-target load. The target voltage is the voltage of the DC bus voltage after being stepped down by the step-down module.

[0008] A voltage detection circuit, the voltage detection circuit is used to detect the DC bus voltage and the actual output voltage of the negative output terminal;

[0009] A control module, wherein the data acquisition end of the control module is connected to the voltage detection circuit to obtain the DC bus voltage and the actual output voltage of the negative output end, and the signal sending end of the control module is connected to the step-down module to control the step-down module to perform step-down.

[0010] In a second aspect, the present invention provides a power supply circuit, which includes the conversion circuit and the rectifier circuit as described above.

[0011] In a third aspect, the present invention provides a wind turbine, comprising the above-mentioned conversion circuit, and the wind turbine is a target load connected to the first frequency converter.

[0012] In a fourth aspect, the present invention provides an air conditioner, comprising the above-mentioned conversion circuit, wherein the conversion circuit is connected to at least one fan and at least one compressor, and the compressor is a non-target load connected to the second inverter.

[0013] Beneficial effects:

[0014] This utility model provides a step-down module. This conversion circuit can reduce the high-voltage DC bus voltage to the target voltage and provide a stable low-voltage power supply for the first inverter, allowing the first inverter to use low-voltage IPM modules and other electronic components, significantly reducing hardware costs. At the same time, by rationally distinguishing the voltage levels of target loads and non-target loads, only the target load (for example, a fan) is designed with a step-down design, avoiding the high cost of using high-voltage voltage components for the entire machine and reducing the overall hardware cost of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a structural diagram of a conversion circuit provided by an embodiment of the present utility model;

[0016] Figure 2 This is a schematic structural diagram of a step-down module used in an embodiment of the present utility model;

[0017] Figure 3 This is a schematic structural diagram of a step-down module used in an embodiment of the present utility model;

[0018] Figure 4 This is a circuit diagram of a conversion circuit provided by an embodiment of the present utility model. DETAILED DESCRIPTION

[0019] In order to enable those skilled in the art to better understand the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of this application.

[0020] With the development of inverter technology, three-phase inverter air conditioners have gradually become a mainstream product in the residential and commercial air conditioning markets. Compared with traditional fixed-frequency air conditioners, inverter air conditioners offer higher energy efficiency and more precise temperature control. They can precisely control the operating status of the compressor and fan by adjusting the motor speed through the inverter.

[0021] A typical three-phase inverter air conditioning unit consists of the following main components:

[0022] Rectifier circuit: used to rectify the input three-phase AC power into high-voltage DC power (such as 540VDC) and provide a stable DC bus voltage for the entire three-phase variable frequency air conditioning unit.

[0023] The compressor's inverter is typically connected directly to the 540V DC bus and controls the compressor motor's speed and torque output. Because the compressor requires significant power, its drive circuit utilizes a high-voltage IPM (Intelligent Power Module).

[0024] Fan inverter: This drives the fan motor, which primarily provides heat dissipation and ventilation. Although the fan's power requirements are relatively low, it shares the same high-voltage DC bus as the compressor, necessitating the use of IPM modules and other high-voltage components of the same high voltage rating.

[0025] The DC bus voltage is 540V, placing high demands on the withstand voltage rating of the power devices in the fan inverter. Consequently, the fan inverter must use IPM modules and other high-voltage components (such as high-voltage MOSFETs, IGBT modules, drive circuits, and protection circuits) with the same voltage rating as the compressor, significantly increasing hardware costs.

[0026] It is understandable that when the motor power is small (for example, the fan can be used only for heat dissipation), a high-voltage IPM module is not necessary, but due to the limitation of the DC bus voltage, high-voltage IPM modules and other high-voltage components are often used in related technologies.

[0027] Furthermore, high-voltage IPM modules often require longer dead time to prevent the switching devices in the upper and lower bridge arms from being simultaneously turned on, potentially causing a short circuit. This can lead to a significant deviation between the inverter output voltage and the actual set voltage, distorting the motor output current waveform. Due to increased motor waveform distortion and harmonic components, the fan may generate greater noise and vibration during operation, affecting the overall stability of the air conditioner and the user experience.

[0028] Therefore, in three-phase variable-frequency air-conditioning units, the fan inverter must use a high-voltage IPM module due to the limitation of the shared DC bus 540V high voltage. This results in excessively high hardware costs for the fan driver and causes problems such as large dead time, current waveform distortion, and high fan noise.

[0029] In summary, in the related art, three-phase variable-frequency air conditioning units have at least one technical problem of excessively high hardware costs. To address this technical problem, this embodiment provides a conversion circuit, which may include: a step-down module, wherein the positive input of the step-down module is connected to a DC bus, the positive output and negative output are connected to a first inverter, and the module provides a target voltage for the first inverter; the negative input and negative output of the step-down module are connected; wherein the DC bus is used to provide a DC bus voltage to a second inverter, the first inverter being connected to a target load, and the second inverter being connected to a non-target load; wherein the target voltage is the DC bus voltage after being stepped down by the step-down module; a voltage detection circuit, wherein the voltage detection circuit is used to detect the DC bus voltage and the actual output voltage of the negative output terminal; and a control module, wherein the control module is used to control the step-down module to step down the DC bus voltage based on the DC bus voltage and the actual output voltage of the negative output terminal, so that the actual output voltage of the negative output terminal approaches the target voltage.

[0030] In this embodiment, by providing a step-down module, the conversion circuit can reduce the high-voltage DC bus voltage to the target voltage and provide a stable low-voltage power supply for the first inverter, thereby allowing the first inverter to select low-voltage IPM modules and other electronic components, which significantly reduces the hardware cost. In addition, since the control module can detect the bus voltage and the output voltage of the step-down module in real time, and perform closed-loop regulation through the voltage detection circuit, it ensures that the target load obtains a stable target voltage and the power supply quality. At the same time, by reasonably distinguishing the voltage levels of the target load and the non-target load, only the target load (for example, it can be a fan) adopts a step-down design, which avoids the high cost of using high-voltage voltage level devices for the entire machine, and achieves a reduction in the overall hardware cost of the system.

[0031] Example

[0032] like Figure 1 As shown, this embodiment provides a conversion circuit, which can be used in the three-phase variable frequency air conditioning unit. The conversion circuit may include:

[0033] A step-down module, wherein the positive input terminal of the step-down module is connected to the DC bus, the positive output terminal and the negative output terminal are connected to the first inverter, and the target voltage is provided for the first inverter. The negative input terminal and the negative output terminal of the step-down module are connected. The DC bus is used to provide a DC bus voltage for the second inverter. The first inverter is an inverter connected to a target load, and the second inverter is an inverter connected to a non-target load. The target voltage is the voltage of the DC bus voltage after being stepped down by the step-down module.

[0034] In this embodiment, the step-down module may be a step-down module composed of at least one step-down circuit. The at least one step-down circuit may be in parallel and connected in parallel between the front-stage circuit and the rear-stage circuit. The front-stage circuit may be a rectifier circuit. The rear-stage circuit may be a first frequency converter and a corresponding target load (for example, a fan). It is understandable that the front-stage circuit may further include an input end of three-phase alternating current. The rear-stage circuit may further include a second frequency converter and a corresponding non-target load (for example, a compressor). The step-down circuit may be a buck-based step-down circuit or a step-down circuit of other circuit structures.

[0035] In this embodiment, the step-down module can also be a step-down module formed by connecting multiple step-down circuits in series, thereby achieving multi-stage step-down. By connecting multiple step-down circuits in series, each step-down circuit takes on a portion of the voltage drop task, which can reduce the voltage stress of the switch tube and other components in each stage of the circuit, thereby effectively improving the overall reliability and working efficiency. It is understandable that under high voltage conditions, the duty cycle of a single-stage step-down circuit may be very low, causing the switching device to operate in a low-efficiency range. Through multi-stage step-down, the duty cycle of the single-stage step-down circuit can be maintained within a more ideal range, thereby improving the overall conversion efficiency.

[0036] Furthermore, the voltage reduction ratios of each step-down circuit can be flexibly adjusted based on actual needs. For example, by changing the reference voltage of each step-down circuit, different step-down levels can be set to meet the load's different voltage requirements and achieve flexible power supply.

[0037] In this embodiment, the buck module may also be a multi-channel synchronous buck shunt buck circuit. For example, it may be a dual-channel synchronous buck shunt buck circuit, a triple-channel, or even a quad-channel synchronous buck shunt buck circuit. In this multi-channel synchronous buck shunt buck circuit, multiple switching devices and corresponding freewheeling diodes may be provided. These multiple switching devices and corresponding freewheeling diodes may reuse an energy storage inductor and a filter capacitor.

[0038] In some embodiments, the buck module may also be a Sep IC buck-boost circuit, which can buck or boost the voltage when the input voltage is higher or lower than the target voltage.

[0039] In some embodiments, the buck module may also be a buck-boost converter (Buck-Boost circuit), which can adjust the output voltage when the input voltage is higher than, equal to, or lower than the output voltage, and can both buck and boost the voltage.

[0040] In some embodiments, the buck module may also be a buck LDO regulator or a Cuk converter, etc.

[0041] In this embodiment, the DC bus is the main power path in the three-phase variable frequency air-conditioning unit. The DC bus is connected to the output end of the rectifier circuit. On the one hand, it transmits the DC power after the three-phase AC rectification to the subsequent conversion module. On the other hand, it supplies power to the second inverter and the corresponding non-target load. The DC bus directly supplies power to the second inverter connected to the non-target load, providing a high-voltage DC power supply that has not been reduced in voltage.

[0042] In this embodiment, the positive output terminal and the negative output terminal are two voltage output ports of the step-down module, which are used to provide a stable target voltage for the first inverter. Specifically, the positive output terminal is the positive output terminal of the step-down module and is used to provide the positive voltage signal of the target voltage to the first inverter. For example, when the step-down module is a buck-based step-down circuit, the positive output terminal can be the connection node between the energy storage inductor and the filter capacitor. The negative output terminal is the negative terminal of the step-down module and can be connected to the negative node of the DC bus. The negative output terminal is used to provide a negative voltage reference for the target voltage for the first inverter. In the step-down module, the negative output terminal is connected to the negative input terminal to form a common connection point, thereby ensuring that the voltage output of the entire step-down module is consistent with the target voltage. It is understood that the voltage relationship between the negative output terminal and the positive output terminal determines the actual output voltage of the step-down module. The voltage detection circuit and control module detect and adjust the voltage between the positive output terminal and the negative output terminal to ensure that the output voltage value is consistent with the required target voltage, thereby achieving stable power supply to the target load.

[0043] In this embodiment, the first inverter can be a power electronic device that provides AC power to the target load. This device is used to drive the connected target load, and its output voltage and frequency can be adjusted according to control requirements to meet the needs of the target load under different operating conditions. For example, when the target load is a fan in an air conditioner, the first inverter can control the fan speed by adjusting the frequency, thereby adjusting the air volume or heat dissipation effect of the air conditioner. The input of the first inverter is connected to the positive and negative output terminals of the step-down module, and receives the target voltage obtained by stepping down the DC bus voltage. This design allows the power module of the first inverter (for example, an IPM module) to use components with lower voltage levels, thereby reducing overall hardware costs. It is understood that the first inverter can include an inverter bridge (for example, it can be composed of multiple switching devices such as IGBTs), which is responsible for converting DC power into AC voltage and providing it to the target load. The first inverter can also include a PWM control unit for controlling the on and off of the inverter bridge switches to adjust the output AC voltage and frequency to achieve speed control of the target load.

[0044] In this embodiment, the target load can be a load that requires power from a voltage that has been stepped down, such as a fan in an air conditioner. The air conditioner can be a three-phase variable frequency air conditioner, or other types of air conditioners. Compared to the compressor, the fan has a lower voltage requirement and a relatively smaller power demand. Therefore, the DC bus voltage can be stepped down by the step-down module before being supplied with power.

[0045] In this embodiment, the target load can be a fan in an air conditioner or an electric valve. It is understood that the electric valve is used to control the flow and pressure of the refrigerant to achieve efficient cooling or heating of the air conditioner. By controlling the amount of refrigerant entering the evaporator, the temperature and pressure of the air conditioner can be precisely adjusted. Therefore, the electric valve can be driven by a low-power DC motor, and its opening and closing degree can be adjusted by the corresponding first inverter (configured with a low-power IPM module) to accurately control the refrigerant flow.

[0046] In this embodiment, the target load may also be a drain pump. It will be appreciated that the drain pump is used to drain condensed water during air conditioner operation. In particular, in wall-mounted or ceiling-mounted air conditioners, condensed water must be promptly drained via the drain pump to ensure proper operation. Drain pumps typically have low power and can be powered by a stepped-down voltage. Their operating speed can be adjusted by the first inverter to accommodate varying operating conditions.

[0047] In some embodiments, the target load may also be an air conditioner shutter adjustment motor, a heat exchanger auxiliary fan, or an electronic air purification device, etc.

[0048] In this embodiment, the target voltage can be expressed as a voltage value obtained after the DC bus voltage is stepped down by the step-down module. This voltage value can provide a stable DC power supply for the target load (for example, a fan, an electric valve or a drainage pump in an air conditioner, etc.). Specifically, the target voltage can be a voltage value lower than the DC bus voltage and matches the voltage tolerance range of the target load. When the target load is a fan, the target voltage can be a voltage value between 200V and 400V, for example, 370V. When the target load is an electric valve or an air conditioner shutter adjustment motor, the target voltage can be a voltage value between 12V and 48V.

[0049] In this embodiment, the second inverter can be represented as an inverter directly connected to the DC bus, which can be used to convert the high-voltage DC bus voltage (for example, 540VDC) into AC power and provide AC power with adjustable frequency and voltage to non-target loads. It is understood that, compared to the first inverter, the input of the second inverter directly receives the unstepped DC bus voltage, while the first inverter receives the lower target voltage after stepping down. It is also understood that the second inverter can include an inverter bridge (for example, composed of multiple switching devices such as IGBTs) and a PWM control unit. Accordingly, it can further include other protection circuits and filtering circuits. The components within the second inverter (for example, switching devices such as IGBTs) can have a higher voltage rating than those of the first inverter, thereby coping with greater voltage stress. The second inverter can be used to drive non-target loads that require high voltage and high power (for example, an air conditioner compressor).

[0050] In this embodiment, the non-target load can be represented as a high-power load that is powered by AC power converted from the DC bus voltage directly received by the second inverter. The non-target load can be a compressor. It is understandable that the compressor is a core component in the air conditioner and is used to compress the refrigerant to achieve the refrigeration cycle. The compressor usually requires a high-power input and is therefore powered directly by the DC bus through the second inverter. The non-target load can also be a high-power motor. It is understandable that in some air conditioners, these air conditioners may include a high-power motor for driving other high-load equipment (for example, a condenser fan, a large centrifugal pump, etc.), and therefore, the high-power motor can also be a non-target load.

[0051] A voltage detection circuit is used to detect the DC bus voltage and the actual output voltage of the negative output terminal.

[0052] In this embodiment, the voltage detection circuit can be represented as a signal acquisition circuit that can measure the DC bus voltage and the actual output voltage of the step-down module in real time and transmit the output signal (which can be a digital signal or an analog signal) to the control module. The voltage detection circuit can provide the control module with accurate voltage detection signals, enabling the control module to dynamically adjust the step-down module based on these signals to ensure that the actual output voltage (VOUT) remains consistent with the target voltage.

[0053] In this embodiment, the voltage detection circuit may include an input terminal, a voltage detection unit, and an output terminal. Specifically, the input terminal may further include a first input terminal and a second input terminal. The first input terminal is connected to the positive input terminal of the DC bus (i.e., the positive input terminal of the step-down module) and is used to detect the DC bus voltage. The second input terminal is connected to the negative output terminal of the step-down module (i.e., the reference point of the output terminal) and serves as a reference for voltage detection. The voltage detection unit (for example, it can be a voltage divider unit that can divide the high voltage signal proportionally to adapt to the signal input range of the control module) is used to collect and process the input voltage signal and convert it into a signal form suitable for output and processing. The output terminal is used to transmit the processed voltage signal to the control module. The output signal can be an analog signal (for example, it can be a proportional voltage signal) or a digital signal (for example, it can be an SPI interface output). More specifically, when the output signal is an analog signal, it can be an analog voltage signal (for example, it can be a 0-5V analog voltage signal), which can be used for sampling by the ADC (analog-to-digital converter) inside the control module. When the output signal is a digital signal, the voltage detection circuit can convert the voltage signal into a digital signal through a built-in ADC and output it to the control module through a digital interface (SPI).

[0054] In some embodiments, the voltage detection circuit may be a resistor divider circuit. The resistor divider circuit may be composed of two or more resistors connected in series, capable of proportionally dividing a high voltage to a low voltage (e.g., 540 VDC to 0-5 V).

[0055] In some embodiments, the voltage detection circuit may also be an isolated voltage detection circuit, which can isolate the high-voltage signal from the low-voltage control circuit through an isolation amplifier and output a low-voltage signal proportional to the high-voltage signal.

[0056] A control module, wherein the data acquisition end of the control module is connected to the voltage detection circuit to obtain the DC bus voltage and the actual output voltage of the negative output end, and the signal sending end of the control module is connected to the step-down module to control the step-down module to perform step-down.

[0057] In this embodiment, the control module is capable of receiving an output signal transmitted by a voltage detection circuit. It is understood that the output signal is a signal representing the DC bus voltage and the actual output voltage (VOUT) of the negative output terminal. Specifically, the control module can receive the output signal from the voltage detection circuit through a data acquisition terminal, that is, an input interface. The output signal can be an analog voltage signal or a digital signal processed by analog-to-digital conversion (ADC). The control module processes the received output signal and compares it with the internally set target voltage to calculate the difference (error value) between the actual output voltage and the target voltage. Based on the error value, the control module can generate a control instruction (e.g., a PWM duty cycle), and then send the control instruction to the step-down module through the signal sending terminal to adjust the working state of the switching device (e.g., IGBT) in the step-down module (e.g., BUCK step-down circuit) to ensure that the output voltage of the step-down module can respond quickly and stabilize within the target voltage range.

[0058] More specifically, when the controller is a digital signal processor (DSP), the data acquisition end can be an analog-to-digital converter (ADC) and a digital input port of the DSP. The output of the voltage detection circuit can be an analog signal or a digital signal. If it is an analog signal, the analog signal is connected to the ADC input port of the DSP. The ADC of the DSP converts the analog voltage signal into a digital value for processing. Accordingly, the signal output end can be a digital output port of the DSP.

[0059] More specifically, when the controller is a microcontroller (MCU), the data acquisition end can be an ADC input pin of the MCU, which is used to receive analog signals from the voltage detection circuit. These ADC pins convert the analog signals into digital signals that can be processed by the MCU. The signal transmission end can be a GPIO port of the MCU, which can be configured in output mode to send digital control signals to the step-down module.

[0060] In this embodiment, the control module may be pre-configured with a voltage closed-loop control algorithm, which controls the output voltage of the step-down module so that the actual output voltage (VOUT) can stably approach the target voltage.

[0061] Specifically, the control module first receives output signals representing the DC bus voltage (VP) and the actual output voltage (VOUT). The control module then compares the actual output voltage (VOUT) with a set target voltage (Vref) and calculates a voltage error signal. This error signal can be expressed as the difference between the target voltage (Vref) and the actual output voltage (VOUT). Next, the control module generates a control signal for adjusting the operating state of the buck module based on the error signal and the DC bus voltage (VP). More specifically, when generating the control signal, the DC bus voltage (VP) can be used as a feedforward signal to predict the output voltage trend based on input voltage fluctuations and perform pre-compensation, thereby improving the dynamic response performance of the control. For example, the ratio of the target voltage (Vref) to the DC bus voltage (VP) can be used as a feedforward signal to generate a more accurate control signal. Finally, the control module converts the generated control signal into a PWM signal for controlling the buck module. The actual output voltage (VOUT) of the buck module is adjusted by adjusting the PWM duty cycle or frequency. It is understandable that the control module can continuously monitor the error between the actual output voltage (VOUT) and the target voltage (Vref), and dynamically adjust the control parameters according to the change of the error to ensure that the actual output voltage (VOUT) can quickly recover to the set value (that is, the target voltage) when the DC bus voltage (VP) fluctuates or the load changes.

[0062] In this embodiment, the voltage loop closed-loop control algorithm may be a PI or PID control algorithm, specifically, the error signal is adjusted by using a proportional-integral (PI) or proportional-integral-derivative (PID) control algorithm.

[0063] In this embodiment, the voltage loop closed-loop control algorithm can also be a feedforward compensation control algorithm. Specifically, this algorithm introduces the DC bus voltage as a feedforward signal based on the PI or PID control algorithm. This DC bus voltage compensation enables a rapid response to DC bus voltage fluctuations, reducing transient fluctuations in the output voltage.

[0064] In some embodiments, the control module may also be pre-configured with an adaptive control algorithm to implement control over the output voltage of the buck module, such that the actual output voltage (VOUT) stably approaches the target voltage. Specifically, control parameters (e.g., proportional gain and integral gain) are automatically adjusted based on dynamic changes in the DC bus voltage and the actual output voltage to improve the control accuracy and stability of the control module under different operating conditions.

[0065] In some embodiments, the control module may also be pre-configured with a fuzzy control algorithm to implement execution control of the buck module's output voltage, such that the actual output voltage (VOUT) stably approaches the target voltage. Specifically, a fuzzy rule base may be pre-configured to define a fuzzy relationship between an input variable (e.g., an error signal) and an output variable (e.g., a PWM signal). A control output is generated through a fuzzy inference mechanism, and the output is defuzzified to obtain an actual control signal.

[0066] In this embodiment, the control module may be a microcontroller-based control module. Specifically, the microcontroller may be an MCU. The MCU may be pre-installed with the aforementioned voltage loop closed-loop control algorithm, adaptive control algorithm, or fuzzy control algorithm.

[0067] In this embodiment, the control module may be a control module based on a digital signal processor. Specifically, the digital signal processor may be a DSP. The DSP may be pre-installed with the aforementioned voltage loop closed-loop control algorithm, adaptive control algorithm, or fuzzy control algorithm.

[0068] In some embodiments, the control module may also be a control module based on an FPGA (field programmable gate array).

[0069] In some embodiments, the control module may also be a control module based on an analog controller.

[0070] In some embodiments, the control module may also be a control module based on an application specific control chip (ASIC).

[0071] This embodiment sets a step-down module, and the conversion circuit can reduce the high-voltage DC bus voltage to the target voltage and provide a stable low-voltage power supply for the first inverter, thereby allowing the first inverter to use low-voltage IPM modules and other electronic components, which significantly reduces the hardware cost. In addition, since the control module can detect the bus voltage and the output voltage of the step-down module in real time, and perform closed-loop regulation through the voltage detection circuit, it ensures that the target load obtains a stable target voltage and the power supply quality. At the same time, by reasonably distinguishing the voltage levels of the target load and non-target load, only the target load (for example, it can be a wind turbine) adopts a step-down design, which avoids the high cost of using high-voltage voltage level devices for the entire machine and achieves a reduction in the overall hardware cost of the system.

[0072] like Figure 2 As shown, in some embodiments, the step-down module includes one step-down circuit or multiple step-down circuits, and the multiple step-down circuits are connected in parallel.

[0073] In this embodiment, the step-down circuit may be a BUCK-based step-down circuit.

[0074] In this embodiment, the step-down circuit may also be a Sep IC step-up / step-down circuit, which can step down or step up the voltage when the input voltage is higher or lower than the target voltage.

[0075] In this embodiment, the buck circuit may also be a buck-boost converter (Buck-Boost circuit), which can adjust the output voltage when the input voltage is higher than, equal to, or lower than the output voltage, and can both buck and boost the voltage.

[0076] In this embodiment, the step-down circuit may also be a step-down LDO regulator or a Cuk converter, etc.

[0077] In this embodiment, when the voltage-reduction module includes multiple voltage-reduction circuits, the voltage-reduction module may be a combination of the multiple voltage-reduction circuits mentioned above.

[0078] In this embodiment, when the buck module includes multiple buck circuits, a parallel connection is adopted so that each buck circuit can share the total load current of the DC bus at the same time. By connecting multiple buck circuits in parallel, the current stress of the electronic devices (for example, switching devices, energy storage inductors and freewheeling diodes) in each buck circuit can be effectively reduced, power loss and heat accumulation can be reduced, thereby improving the reliability and efficiency of the overall circuit. In addition, the parallel structure can ensure that when a single buck circuit fails, the other parallel buck circuits continue to operate normally, thereby enhancing the redundancy and fault tolerance of the circuit and effectively improving the stability and operational safety of the circuit. Therefore, this embodiment can significantly improve the overall load capacity and efficiency while maintaining the stability of the output voltage, and is suitable for high-reliability power supply systems in high-power scenarios.

[0079] like Figure 3 As shown, in some embodiments, the step-down module includes multiple step-down circuits, and the multiple step-down circuits are connected in series.

[0080] In this embodiment, the step-down circuit may be a BUCK-based step-down circuit.

[0081] In this embodiment, the step-down circuit may also be a Sepic buck-boost circuit. The Sepic buck-boost circuit can step down or boost the voltage when the input voltage is higher or lower than the target voltage.

[0082] In this embodiment, the buck circuit may also be a buck-boost converter (Buck-Boost circuit), which can adjust the output voltage when the input voltage is higher than, equal to, or lower than the output voltage, and can both buck and boost the voltage.

[0083] In this embodiment, the step-down circuit may also be a step-down LDO regulator or a Cuk converter, etc.

[0084] In this embodiment, the step-down module may be a combination of the above-mentioned multiple step-down circuits.

[0085] In this embodiment, a multi-channel buck circuit structure connected in series enables step-by-step voltage reduction, thereby optimizing the voltage conversion ratio at each stage, improving the efficiency of the buck module, and reducing energy loss and heat accumulation. The series buck circuit can disperse the voltage drop at each stage, thereby reducing the voltage stress experienced by the voltage conversion devices at each stage. This allows the use of power devices with lower withstand voltage ratings and lower losses, improving the operating efficiency of the entire circuit.

[0086] In this embodiment, the step-down module includes multiple step-down circuits connected in series, enabling each step-down circuit to progressively reduce the DC bus voltage, thereby achieving multi-stage voltage conversion and hierarchical step-down regulation. The use of multiple step-down circuits connected in series enables the voltage to be gradually reduced at multiple voltage nodes, significantly reducing the voltage stress experienced by the electronic components (e.g., switching devices, energy storage inductors, and freewheeling diodes) in each step-down circuit. This reduces the required withstand voltage rating of the components, enabling the selection of lower-voltage, lower-cost power components, further reducing overall hardware costs.

[0087] In some embodiments, each of the step-down circuits includes at least:

[0088] A switching device, wherein a voltage input end of the switching device is connected to a DC bus, and a signal input end of the switching device is connected to the control module.

[0089] In this embodiment, the voltage input terminal of the switch device is also the positive input terminal of the step-down module.

[0090] In this embodiment, the switching device can be a MOSFET (metal oxide semiconductor field effect transistor), an IGBT (insulated gate bipolar transistor), a triode, a silicon carbide field effect transistor, a bipolar transistor, etc.

[0091] An energy storage inductor, one end of which is connected to the output end of the switching device.

[0092] When the switching device is an IGBT, one end of the energy storage inductor is connected to the emitter of the IGBT. The collector of the IGBT is connected to the DC bus. When the IGBT is turned on, the DC voltage flows to the emitter through the collector of the IGBT, and is applied to one end of the energy storage inductor, and the energy storage inductor begins to store energy. When the IGBT is turned off, since the current in the energy storage inductor cannot change instantaneously, the current continues to flow through the freewheeling diode (connected between the energy storage inductor and the load), maintaining the continuity of the load current.

[0093] When the switching device is a MOSFET, and when the MOSFET is an N-channel MOSFET, one end of the energy storage inductor is connected to the source of the MOSFET, and the drain of the MOSFET is connected to the DC bus.

[0094] When the switching device is a transistor, one end of the energy storage inductor is connected to the emitter of the transistor, and the collector of the transistor is connected to the DC bus.

[0095] A freewheeling diode, wherein the cathode of the freewheeling diode is connected to the output end of the switching device, and the anode of the freewheeling diode is connected to the first inverter.

[0096] A filter capacitor, one end of the filter capacitor is connected to the other end of the energy storage inductor, and is connected to the first inverter as the positive output end of the step-down module, and the other end of the filter capacitor is connected to the first inverter and the positive electrode of the freewheeling diode as the negative output end.

[0097] It is understood that the positive electrode of the freewheeling diode is connected to the first inverter on one hand and to the other end of the filter capacitor on the other hand. The positive electrode of the freewheeling diode and the other end of the filter capacitor are the negative output terminal of the step-down module. The intersection of the energy storage inductor and the filter capacitor is the positive output terminal of the step-down module.

[0098] In this embodiment, each buck circuit may further include a drive circuit. The drive circuit is used to provide amplification and isolation of the gate drive signal between the control module and the switching device. It is understandable that since the control signal (for example, it can be a PWM signal) of the control module has a low voltage and cannot directly drive the high-power switching device, it is necessary to use a drive circuit for signal amplification. In this embodiment, each buck circuit adopts a buck topology consisting of a switching device, an energy storage inductor, a freewheeling diode and a filter capacitor, and realizes efficient buck regulation of the DC bus voltage based on the reasonable configuration of each component. This topology can control the charging and discharging process of the inductor by turning on and off the switching device in each switching cycle, effectively realizing a smooth conversion of the input DC bus voltage to the target voltage; through the energy storage of the energy storage inductor and the conduction of the freewheeling diode, the continuity of the current can be maintained, avoiding the voltage ripple caused by the discontinuous current, thereby reducing the ripple level of the output voltage; at the same time, the addition of the filter capacitor can further smooth the output voltage, reduce the voltage fluctuation caused by the current change, and effectively improve the stability and regulation accuracy of the output voltage. A step-down circuit employing this structure can maintain high conversion efficiency under varying input voltage conditions, and can easily achieve precise control of varying output voltages by adjusting the duty cycle of the switching device. Therefore, this embodiment can achieve efficient and stable conversion of a variety of target voltages and is suitable for complex application scenarios with varying input voltages and loads, effectively improving the circuit's voltage regulation performance and operating efficiency.

[0099] In some embodiments, the step-down module may include at least:

[0100] A first switching device and a second switching device, wherein voltage input terminals of the first switching device and the second switching device are both connected to the DC bus, and signal input terminals of the first switching device and the second switching device are both connected to the control module.

[0101] In this embodiment, the first switching device and the second switching device can be MOSFET (metal oxide semiconductor field effect transistor), IGBT (insulated gate bipolar transistor), triode, silicon carbide field effect transistor or bipolar transistor, etc.

[0102] An energy storage inductor, one end of which is connected to the output end of the first switching device and the output end of the second switching device respectively.

[0103] a first freewheeling diode and a second freewheeling diode, wherein the cathodes of the first freewheeling diode and the second freewheeling diode are respectively connected to the output ends of the first switching device and the second switching device, and the anodes of the first freewheeling diode and the second freewheeling diode are connected to the first inverter;

[0104] A filter capacitor, one end of the filter capacitor is connected to the other end of the energy storage inductor, and is connected to the first inverter as the positive output end of the step-down module, and the other end of the filter capacitor is connected to the first inverter and the positive poles of the first and second freewheeling diodes as the negative output end.

[0105] In this embodiment, the step-down module may further include a drive circuit. The drive circuit is used to provide amplification and isolation of the gate drive signal between the control module and the first switching device and the second switching device. It is understandable that since the control signal of the control module (for example, a PWM signal) has a low voltage and cannot directly drive the high-power switching device, a drive circuit is required to amplify the signal. Figure 4 In a specific embodiment, the first switching device may be UND1, and the second switching device may be UND2. The first freewheeling diode may be diode D1, and the second freewheeling diode may be diode D2. The energy storage inductor may be energy storage inductor L2. The filter capacitor may be filter capacitor C3. The control module may be an MCU.

[0106] Specifically, UND1 and UND2 are two parallel IGBT switching devices used to implement periodic current regulation of the high-voltage DC bus voltage to the downstream energy storage inductor. The collectors of UND1 and UND2 serve as voltage input terminals and are connected to the DC bus voltage node (VP). The emitters serve as current output terminals and are used to connect to one end of the energy storage inductor. The signal input terminals (i.e., gates) of UND1 and UND2 are connected to the MCU to receive PWM control signals to achieve the on and off of the IGBT. The on and off of UND1 and UND2 are precisely controlled by the PWM signal of the MCU. By adjusting the PWM duty cycle, the output voltage (VOUT) can be precisely controlled. The energy storage inductor L2 is an energy storage element. When UND1 and UND2 are turned on and off, the current stores and releases energy through the energy storage inductor L2, thereby maintaining the continuity of the load current.

[0107] One end of the energy storage inductor L2 is connected to the emitters of UND1 and UND2, and the other end is connected to one end of the filter capacitor C3. This inductor L2 further serves as the positive output of the step-down circuit, supplying power to the first inverter (target load). When UND1 and UND2 are on, the energy storage inductor L2 gradually stores energy, causing the current to increase linearly. When UND1 and UND2 are off, the energy storage inductor L2 releases energy and continues to supply current to the target load.

[0108] Freewheeling diodes D1 and D2 provide a reverse freewheeling path for the inductor current when UND1 and UND2 are turned off, ensuring that the current is not abruptly interrupted. The cathodes of freewheeling diodes D1 and D2 are connected to the emitters of UND1 and UND2, respectively, and to one end of the energy storage inductor L2. The anodes of freewheeling diodes D1 and D2 are connected to the other end of filter capacitor C3.

[0109] The function of the filter capacitor C3 is to reduce the impact of current fluctuations on the actual output voltage by the current released by the energy storage inductor L2, thereby providing a stable target voltage. One end of the filter capacitor C3 is connected to the other end of the energy storage inductor L2, and this intersection serves as the positive output terminal of the buck module. The other end of the filter capacitor C3 is connected to the positive poles of the freewheeling diodes D1 and D2, and further serves as the negative output terminal of the entire buck module, connected to the common reference terminal of the load (the first inverter).

[0110] The MCU is the circuit's control module. It receives inputs from the voltage detection circuit (DC bus voltage VP and actual output voltage VOUT) and, based on the voltage-loop closed-loop control algorithm, outputs PWM signals to control the on-time and conduction timing of UND1 and UND2. The PWM signals generated by the MCU are connected to the gates of UND1 and UND2, controlling the switching states of the two IGBTs, thereby achieving precise control of the output voltage.

[0111] In this embodiment, by introducing a dual-path synchronous BUCK shunt buck circuit, each path includes an independent switching device (first and second switching devices), a freewheeling diode (first and second freewheeling diodes) and a shared energy storage inductor and filter capacitor, which can realize the shunt control of multiple current channels, thereby effectively distributing the current of each path through a parallel structure under the same DC bus voltage, reducing the current stress of each switching device and current path. This dual-path buck topology can significantly improve the current carrying capacity and power density of the buck module, and due to the adoption of a two-path synchronous control strategy, each switching device can be synchronized and adjusted through precise PWM, while ensuring the stability of the output voltage, reducing the voltage ripple and power loss caused by inconsistent current transient response, thereby greatly improving the dynamic response performance of the voltage regulation. Moreover, the design of shared energy storage inductor and filter capacitor can effectively simplify the circuit structure, reduce the inductor volume and the number of filter elements, thereby reducing cost and circuit complexity.

[0112] In some embodiments, the conversion circuit may further include:

[0113] A bus filter inductor, one end of which is connected to the positive electrode of the front-stage rectifier circuit, and the other end of which is connected to the voltage input end of the first switching device and the second switching device, is used to suppress the current ripple on the DC bus.

[0114] like Figure 4 In a specific embodiment, the bus filter inductor may be a bus filter inductor L1. One end of the bus filter inductor L1 is connected to the pre-stage rectifier circuit shown in the figure. The other end of the bus filter inductor L1 is connected to UND1 and UND2 shown in the figure.

[0115] In this embodiment, by introducing a bus filter inductor into the conversion circuit, current ripple on the DC bus can be effectively suppressed, improving the stability and power quality of the DC bus voltage. One end of the bus filter inductor is connected to the positive electrode of the pre-stage rectifier circuit, and the other end is connected to the voltage input terminals of the first switching device and the second switching device. It is used to form a low-frequency current filter path in the high-voltage DC bus, reducing the high-frequency ripple component in the rectified DC bus current and preventing DC bus voltage fluctuations caused by current fluctuations.

[0116] In some embodiments, the conversion circuit may further include:

[0117] A first bus filter capacitor, one end of which is connected to the other end of the bus filter inductor and the voltage input ends of the first switching device and the second switching device respectively.

[0118] A second bus filter capacitor, one end of the second bus filter capacitor is connected to the other end of the first bus filter capacitor, and the other end of the second bus filter capacitor is connected to the negative electrode of the front-stage rectifier circuit.

[0119] like Figure 4 In a specific embodiment, the first bus filter capacitor may be a bus filter capacitor C1, and the second bus filter capacitor may be a bus filter capacitor C2.

[0120] In this embodiment, by adding a first bus filter capacitor and a second bus filter capacitor, the filtering effect and power stability of the DC bus voltage can be further enhanced. Specifically, one end of the first bus filter capacitor is connected to the other end of the bus filter inductor and is directly connected to the voltage input end of the first switching device and the second switching device, which can form an effective LC filter network on the basis of the bus filter inductor, further absorb the high-frequency voltage ripple in the DC bus, and suppress the spikes and oscillations generated by the DC bus voltage during the switching process, thereby providing a more stable input voltage for the lower circuit. The second bus filter capacitor is connected in series with the first bus filter capacitor, and its other end is connected to the negative terminal of the rectifier circuit to form a dual-capacitor filter structure across the bus voltage. This dual-capacitor structure can not only enhance the high-frequency filtering effect on the input voltage, but also provide additional charge buffering when the load current changes, effectively suppressing transient fluctuations in the DC bus voltage. Through this multi-stage filtering design, this implementation can significantly improve the stability of the DC bus voltage, reduce the impact of current and voltage ripple on switching devices, and thus enhance the stability and conversion efficiency of the entire circuit. At the same time, it significantly reduces switching noise and electromagnetic interference, ensuring the reliable operation of the step-down circuit under complex working conditions.

[0121] like Figure 4 As shown, in a specific embodiment, the embodiment may include: a rectifier circuit, a dual-synchronous buck shunt and voltage-step-down circuit, and a compressor inverter circuit and a fan inverter circuit. The rectifier circuit and compressor inverter circuit are used to control and drive the compressor for normal and reliable operation. The dual-synchronous buck shunt and voltage-step-down circuit and fan inverter circuit reduce the three-phase bus voltage of 540V to the single-phase bus voltage of 310V. Using a voltage sampling circuit and a voltage closed-loop control algorithm, they collect the voltage values ​​across the energy storage inductor L2 and transmit them to the MCU to calculate and control the duty cycle of the PWM wave. This also controls the on / off switching of the IGBT to provide independent power to the fan. Since the voltage is stepped down from 540VDC to a low voltage of 310VDC, a low-voltage IPM power module can be used first. This effectively reduces dead time, thereby improving the voltage utilization of the first inverter output and reducing the motor current distortion rate, effectively improving motor noise.

[0122] When UND1 and UND2 are conducting, energy storage inductor L2 is magnetized and stores energy. The current flowing through energy storage inductor L2 increases linearly, simultaneously charging filter capacitor C3 and providing energy to the load. When conducting, the bridge rectifier rectifies the voltage to 540VDC. Current flows through bus filter inductor L1, bus filter capacitors C1 / C2, switching transistors UND1 / UND2, energy storage inductor L2, and the load. The diodes exhibit single-phase conduction characteristics, resulting in no current flow, and filter capacitor C3 charges. Since the inductor current cannot change suddenly, it shifts from small to large. At this point, the inductor stores energy and charges, with the left side positive and the right side negative. The inductor voltage VL = VOUT - VP.

[0123] When UND1 and UND2 are off, the inductor current cannot change suddenly. At this time, the energy storage inductor L2 is equivalent to the power supply discharging, that is, the right side is positive and the left side is negative. The current flows out through the right side of the energy storage inductor L2, through the load and diodes D1 / D2, and back to the left side of the inductor. The inductor voltage VL = VOUT.

[0124] After stable operation, the inductor volt-second conservation law applies. When conducting, the inductor voltage is equal to the input voltage VP; when off, the inductor voltage is equal to the output voltage VOUT. Let T be the period, TON be the on-time, TOFF be the off-time, and D be the duty cycle (D = TON / T). Based on the inductor volt-second conservation law, we have:

[0125] Von*TON=Voff*TOFF

[0126] When on, Von=VL=VOUT-VP

[0127] When turned off, Voff=VL=VOUT

[0128] VOUT*TON=(VOUT-VP)*TOFF

[0129] The final conclusion is: the output voltage is equal to the input voltage = TON = DT, and D is less than 1, so voltage reduction is achieved.

[0130] TON=(VP-VOUT) / VOUT

[0131] Three-phase, high-power, variable-frequency air conditioning units have high cooling capacities, requiring a high compressor output power that far exceeds the fan power. To achieve a certain cooling capacity, the bus voltage VP rectified by the three-phase rectifier bridge directly powers the compressor inverter bridge, ensuring reliable compressor operation. The fan in the variable-frequency unit serves only as a heat sink, requiring only that its speed meet the required requirements. Therefore, the stepped-down voltage VOUT powers the fan inverter bridge. The inverter component, the IPM module, can be a single-phase, low-power material, and the motor can be a more cost-effective single-phase DC motor. Since the low-voltage IPM module allows for a shorter dead time, it improves the inverter output voltage utilization, improves motor current distortion, and thus reduces motor noise.

[0132] This embodiment provides a power supply circuit, which includes the above-mentioned conversion circuit and rectification circuit.

[0133] This embodiment provides a wind turbine, which includes the above-mentioned conversion circuit. The wind turbine is a target load connected to the first inverter.

[0134] This embodiment provides an air conditioner, comprising the conversion circuit, wherein the conversion circuit is connected to at least one fan and at least one compressor, wherein the compressor is a non-target load connected to the second inverter.

[0135] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in a sequence other than those illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0136] Optionally, the specific examples in this embodiment may refer to the examples described in the above embodiments, and this embodiment will not be described in detail here.

[0137] The serial numbers of the above embodiments of the present application are for description only and do not represent the advantages or disadvantages of the embodiments.

[0138] In the above embodiments of the present application, the description of each embodiment has its own focus. For parts that are not described in detail in a certain embodiment, please refer to the relevant description of other embodiments.

[0139] The above is only a preferred embodiment of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A conversion circuit, characterized in that: The conversion circuit at least includes: A step-down module, wherein the positive input terminal of the step-down module is connected to the DC bus, the positive output terminal and the negative output terminal are connected to the first inverter, and the target voltage is provided to the first inverter. The negative input terminal and the negative output terminal of the step-down module are connected. The DC bus is used to provide a DC bus voltage to the second inverter. The first inverter is an inverter connected to the target load, and the second inverter is an inverter connected to the non-target load. The target voltage is the voltage of the DC bus voltage after being stepped down by the step-down module. A voltage detection circuit, the voltage detection circuit is used to detect the DC bus voltage and the actual output voltage of the negative output terminal; A control module, wherein the data acquisition end of the control module is connected to the voltage detection circuit to obtain the DC bus voltage and the actual output voltage of the negative output end, and the signal sending end of the control module is connected to the step-down module to control the step-down module to perform step-down.

2. The circuit according to claim 1, wherein: The step-down module includes one step-down circuit or multiple step-down circuits, and the multiple step-down circuits are connected in parallel.

3. The circuit according to claim 1, wherein: The step-down module includes multiple step-down circuits, which are connected in series.

4. The circuit according to claim 2 or 3, characterized in that Each step-down circuit at least includes: a switching device, wherein a voltage input terminal of the switching device is connected to a DC bus, and a signal input terminal of the switching device is connected to the control module; an energy storage inductor, one end of which is connected to the output end of the switching device; a freewheeling diode, wherein the cathode of the freewheeling diode is connected to the output end of the switching device, and the anode of the freewheeling diode is connected to the first inverter; A filter capacitor, one end of the filter capacitor is connected to the other end of the energy storage inductor, and is connected to the first inverter as the positive output end of the step-down module, and the other end of the filter capacitor is connected to the first inverter and the positive electrode of the freewheeling diode as the negative output end.

5. The circuit according to claim 1, wherein: The step-down module at least includes: a first switching device and a second switching device, wherein voltage input terminals of the first switching device and the second switching device are both connected to the DC bus, and signal input terminals of the first switching device and the second switching device are both connected to the control module; an energy storage inductor, one end of which is connected to the output end of the first switching device and the output end of the second switching device respectively; a first freewheeling diode and a second freewheeling diode, wherein the cathodes of the first freewheeling diode and the second freewheeling diode are respectively connected to the output ends of the first switching device and the second switching device, and the anodes of the first freewheeling diode and the second freewheeling diode are connected to the first inverter; A filter capacitor, one end of the filter capacitor is connected to the other end of the energy storage inductor, and is connected to the first inverter as the positive output end of the step-down module, and the other end of the filter capacitor is connected to the first inverter and the positive poles of the first and second freewheeling diodes as the negative output end.

6. The circuit according to claim 5, characterized in that The conversion circuit further includes: A bus filter inductor, one end of which is connected to the positive electrode of the front-stage rectifier circuit, and the other end of which is connected to the voltage input end of the first switching device and the second switching device, is used to suppress the current ripple on the DC bus.

7. The circuit according to claim 6, characterized in that The conversion circuit further includes: a first bus filter capacitor, one end of which is connected to the other end of the bus filter inductor and the voltage input ends of the first switching device and the second switching device respectively; A second bus filter capacitor, one end of the second bus filter capacitor is connected to the other end of the first bus filter capacitor, and the other end of the second bus filter capacitor is connected to the negative electrode of the front-stage rectifier circuit.

8. A power supply circuit, characterized in that: The power supply circuit includes the conversion circuit and the rectifier circuit as described in any one of claims 1 to 7.

9. A fan, characterized in that: The wind turbine includes the conversion circuit according to any one of claims 1 to 7, and the wind turbine is a target load connected to the first inverter.

10. An air conditioner, characterized in that: The air conditioner comprises the conversion circuit according to any one of claims 1 to 7, wherein the conversion circuit is connected to at least one fan and at least one compressor, and the compressor is a non-target load connected to the second inverter.

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