Soft start circuit, soft start control method, controller and air conditioner

Abstract

The present application relates to a soft start circuit, a soft start control method, a controller and an air conditioner. The soft start circuit includes a control module, a circuit switching module, a rectification module, a PFC switch tube and a bus capacitor. The input end of the rectification module is connected to an input AC power supply, and the output end of the rectification module is connected to the PFC switch tube. The control module switches the connection relationship between the PFC switch tube and the bus capacitor through the circuit switching module. When the PFC switch tube is in series with the bus capacitor, the bus capacitor is charged, and the bus capacitor enters the soft start working state; when the PFC switch tube is in parallel with the bus capacitor, the bus capacitor is boosted, and the bus capacitor enters the boosting working state. The present application can reduce the current in the circuit during the bus charging process, reduce the loss of the impact current on the rear-end electronic components, and eliminate multiple cement resistors, effectively saving space and reducing costs.

Description

Technical Field

[0001] This application belongs to the technical field of soft start, and particularly relates to a soft start circuit, a soft start control method, a controller and an air conditioner. Background Art

[0002] With the continuous improvement of social living standards, the use of air conditioner appliances has gradually become popular. Due to the advantages of variable-frequency air conditioners such as low cost, low noise, and high performance, they have been widely used. And the soft start control circuit, which is an important part of the variable-frequency air conditioner, is the key to improving the overall performance of the machine. Since the soft start charging circuit is used to suppress the impact of inrush current on the power grid during startup, reduce current harmonics, and improve the startup performance of the variable-frequency air conditioner, it is widely used in the outdoor unit of the variable-frequency air conditioner. The commonly used soft start charging scheme in variable-frequency air conditioners mainly connects a resistor in series at the input end of the power supply and a relay in parallel. However, at the moment of power-on, the resistor and inductor connected in series in the circuit can only suppress the inrush current, but cannot suppress the impact current. As the usage time of the air conditioner increases, the excessive impact current during startup charging will shorten the service life of the components at the back end of the circuit and reduce the reliability of the air conditioner operation.

[0003] In the related art, a cement resistor is added to the bus pre-charging circuit to reduce the loss of the back-end electronic components caused by the impact current, but it will occupy too much space on the control board and is not conducive to the heat dissipation of the controller. Summary of the Invention

[0004] To at least overcome to some extent the problems that the traditional soft start circuit cannot suppress the impact current, resulting in a reduction in the reliability of air conditioner operation, and adding a cement resistor to reduce the impact current will occupy too much space on the control board and is not conducive to the heat dissipation of the controller, this application provides a soft start circuit, a soft start control method, a controller and an air conditioner.

[0005] In a first aspect, this application provides a soft start circuit, including:

[0006] A control module, a circuit switching module, a rectification module, a PFC switch tube and a bus capacitor;

[0007] The input end of the rectification module is connected to the input AC power supply;

[0008] The output end of the rectification module is connected to the PFC switch tube;

[0009] The control module switches the connection relationship between the PFC switch tube and the bus capacitor through the circuit switching module. When the PFC switch tube is in series with the bus capacitor, the bus capacitor is charged, and the bus capacitor enters the soft start working state; when the PFC switch tube is in parallel with the bus capacitor, the bus capacitor is boosted, and the bus capacitor enters the boost working state.

[0010] Further, the circuit switching module includes:

[0011] A first switch, a second switch, and a third switch;

[0012] The first switch is disposed between the emitter of the PFC switch tube and the positive pole of the bus capacitor;

[0013] The second switch is disposed between the collector of the PFC switch tube and the negative pole of the bus circuit;

[0014] The third switch is disposed between the collector of the PFC switch tube and the positive pole of the bus circuit.

[0015] Further, the control module switches the connection relationship between the PFC switch tube and the bus capacitor through the circuit switching module, including:

[0016] The control module controls the first switch and the second switch to close and the third switch to open, so as to control the PFC switch tube to be connected in parallel with the bus capacitor;

[0017] The control module controls the first switch and the second switch to open and the third switch to close, so as to control the PFC switch tube to be connected in series with the bus capacitor.

[0018] Further, at least one of the first switch, the second switch, or the third switch is a relay, a circuit breaker, a contactor, a thyristor device, or a controllable semiconductor device.

[0019] Further, it further includes:

[0020] A voltage sampling module, the voltage sampling module is connected to the rectification circuit;

[0021] The voltage sampling module includes a first resistor and a second resistor, and the resistance value of the first resistor is greater than that of the second resistor;

[0022] The first resistor and the second resistor are used for dividing the DC voltage output by the rectification module; the voltage sampling module is used for collecting the DC voltage value on the second resistor;

[0023] The control module is further used for calculating the DC voltage value output by the rectification module according to the DC voltage value on the second resistor collected by the voltage sampling module.

[0024] Further, the control module is further used for:

[0025] Setting a plurality of voltage intervals with the same voltage change amplitude;

[0026] Take the voltage range with the minimum average voltage corresponding to the voltage range as the charging voltage range;

[0027] When the DC voltage value output by the rectification module enters the charging voltage range, control the PFC switch tube to conduct;

[0028] When reaching the maximum value of the charging voltage range, control the PFC switch tube to cut off, and determine the voltage range adjacent to the current charging voltage range as the charging voltage range until the bus capacitor voltage reaches the voltage maximum value.

[0029] Further, the voltage maximum value is , where U is the effective value of the voltage of the input AC power supply.

[0030] Further, it further includes:

[0031] A PFC inductor, which is arranged between the positive output terminal of the rectification module and the positive pole of the bus capacitor, and is used to charge or boost the bus capacitor.

[0032] In a second aspect, the present application provides a soft start control method, including:

[0033] Collect the DC voltage value in the soft start circuit;

[0034] According to the DC voltage value in the soft start circuit, control the connection relationship between the PFC switch tube and the bus capacitor. When the PFC switch tube is in series with the bus capacitor, charge the bus capacitor, and the bus capacitor enters the soft start working state; when the PFC switch tube is in parallel with the bus capacitor, boost the bus capacitor, and the bus capacitor enters the boost working state.

[0035] Further, the collecting the DC voltage value in the soft start circuit includes:

[0036] Divide the DC voltage output by the rectification module in the soft start circuit;

[0037] Collect the DC voltage value on the voltage dividing resistor;

[0038] Calculate the DC voltage value in the soft start circuit according to the DC voltage value on the voltage dividing resistor.

[0039] Further, the controlling the working state of the PFC switch tube according to the DC voltage value in the soft start circuit includes:

[0040] Set multiple voltage ranges with the same voltage change amplitude;

[0041] Take the voltage range with the minimum average voltage corresponding to the voltage range as the charging voltage range;

[0042] When the DC voltage value in the soft start circuit enters the charging voltage range, control the PFC switch tube to conduct;

[0043] When reaching the maximum value of the charging voltage range, control the PFC switch tube to cut off, and determine the voltage range adjacent to the current charging voltage range as the charging voltage range until the bus capacitor voltage reaches the maximum voltage value.

[0044] In a third aspect, the present application provides a controller, including:

[0045] The soft start circuit as described in the first aspect.

[0046] In a fourth aspect, the present application provides an air conditioner, including:

[0047] The controller as described in the third aspect.

[0048] The technical solutions provided by the embodiments of the present application may include the following beneficial effects:

[0049] The soft start circuit, soft start control method, controller and air conditioner provided by the embodiments of the present invention. The soft start circuit includes a control module, a circuit switching module, a rectification module, a PFC switch tube and a bus capacitor. The input end of the rectification module is connected to the input AC power supply, and the output end of the rectification module is connected to the PFC switch tube. The control module switches the connection relationship between the PFC switch tube and the bus capacitor through the circuit switching module. When the PFC switch tube is connected in series with the bus capacitor, charge the bus capacitor, and the bus capacitor enters the soft start working state; when the PFC switch tube is connected in parallel with the bus capacitor, boost the bus capacitor, and the bus capacitor enters the boost working state. It can reduce the current in the circuit during the bus charging process, reduce the loss of the impact current on the rear-end electronic components, and eliminate multiple cement resistors, effectively saving space and reducing costs.

[0050] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] The drawings herein are incorporated into the specification and form a part of the specification, showing embodiments consistent with the present application, and are used together with the specification to explain the principles of the present application.

[0052] Figure 1 It is a circuit diagram of a soft start circuit provided by an embodiment of the present application.

[0053] Figure 2 It is a functional structure diagram of a soft start circuit provided by another embodiment of the present application.

[0054] Figure 3A waveform diagram of the turn-on time of a switching tube and the bus voltage provided by an embodiment of the present application.

[0055] Figure 4 A flowchart of a soft start control method provided by an embodiment of the present application.

[0056] Figure 5 A flowchart of another soft start control method provided by an embodiment of the present application. Detailed implementation manners

[0057] To make the objectives, technical solutions and advantages of the present application clearer, the technical solutions of the present application will be described in detail below. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other implementation manners obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts shall fall within the scope protected by the present application.

[0058] Figure 1 A functional structure diagram of a soft start circuit provided by an embodiment of the present application, as Figure 1 shown. The soft start circuit includes:

[0059] A control module 1, a circuit switching module 2, a rectification module 3, a PFC (Power Factor Correction) switching tube 5, and a bus capacitor 4;

[0060] The input end of the rectification module 3 is connected to an input AC power supply;

[0061] The output end of the rectification module 3 is connected to the PFC switching tube 5;

[0062] The control module 1 switches the connection relationship between the PFC switching tube 5 and the bus capacitor 4 through the circuit switching module 2. When the PFC switching tube 5 is in series with the bus capacitor 4, the bus capacitor 4 is charged, and the bus capacitor 4 enters the soft start working state; when the PFC switching tube 5 is in parallel with the bus capacitor 4, the bus capacitor 4 is boosted, and the bus capacitor 4 enters the boost working state.

[0063] In this embodiment, it further includes:

[0064] A PFC inductor 6, which is arranged between the positive output end of the rectification module 3 and the positive electrode of the bus capacitor 4, and is used to charge or boost the bus capacitor 4.

[0065] In this embodiment, it further includes:

[0066] A voltage sampling module 7, and the voltage sampling module 7 is connected to the rectification circuit 3;

[0067] The voltage sampling module 7 includes a first resistor and a second resistor, and the resistance value of the first resistor is greater than that of the second resistor;

[0068] The first resistor and the second resistor are used to divide the DC voltage output by the rectification module; the voltage sampling module 7 is used to collect the DC voltage value on the second resistor;

[0069] The control module 1 is further configured to calculate the DC voltage value output by the rectification module 3 according to the DC voltage value on the second resistor collected by the voltage sampling module 7.

[0070] Since the DC voltage value output by the rectification module 3 is relatively high, collecting the DC voltage output by the rectification module 3 after voltage division can reduce the impact of the large voltage on the controller. Since the resistance value of the second resistor is much smaller than that of the first resistor, the voltage division value corresponding to the second resistor is smaller. Inputting the smaller voltage division value into the controller and then calculating the DC voltage value output by the rectification module 1 can improve the system reliability.

[0071] In the traditional soft start circuit, a cement resistor is added to the bus pre-charge circuit to reduce the loss of the impact current on the backend electronic components, but it will occupy too much space on the control board, waste cost and is not conducive to the heat dissipation of the controller.

[0072] In this embodiment, the soft start circuit includes a control module, a circuit switching module, a rectification module, a PFC switch tube and a bus capacitor. The input end of the rectification module is connected to the input AC power supply, and the output end of the rectification module is connected to the PFC switch tube. The control module switches the connection relationship between the PFC switch tube and the bus capacitor through the circuit switching module. When the PFC switch tube is in series with the bus capacitor, the bus capacitor is charged, and the bus capacitor enters the soft start working state; when the PFC switch tube is in parallel with the bus capacitor, the bus capacitor is boosted, and the bus capacitor enters the boost working state, which can reduce the current in the circuit during the bus charging process, reduce the loss of the impact current on the backend electronic components, and eliminate multiple cement resistors, effectively saving space and reducing cost.

[0073] Figure 2 The circuit diagram of the soft start circuit provided by another embodiment of the present application is as Figure 2 shown. Based on the previous embodiment, the circuit switching module in this soft start circuit includes:

[0074] The first switch K 1 , the second switch K 2 and the third switch K 3 ;

[0075] The first switch K 1 is arranged between the emitter of the PFC switch tube Q and the positive pole of the bus capacitor C;

[0076] Second switch K 2 It is arranged between the collector of the PFC switch tube Q and the negative electrode of the bus circuit C;

[0077] The third switch K 3 It is set between the collector of the PFC switch tube Q and the positive electrode of the bus circuit C.

[0078] In this embodiment, the control module switches the working state of the PFC switch tube through the circuit switching module, including:

[0079] The control module controls the first switch K 1 and the second switch K 2 Close, the third switch K 3 Disconnect, control the PFC switch tube Q to be connected in parallel with the bus capacitor C;

[0080] The control module 1 controls the first switch K 1 and the second switch K 2 Disconnect, the third switch K 3 Closed, controlling the PFC switch tube Q to be connected in series with the bus capacitor C.

[0081] In some embodiments, the first switch K 1 , the second switch K 2 Or the third switch K 3 It is at least one of a relay, a circuit breaker, a contactor, a thyristor device, and a controllable semiconductor device.

[0082] It should be noted that the soft start circuit of the present application can be used for any soft start system with controllable switching tubes around the bus circuit. The switching device is used to switch the controllable switching tube between the step-up and step-down state and the bus pre-charging state, thereby achieving the soft start of the bus voltage by using the system's own controllable switching tube and adding switching devices.

[0083] In some embodiments, the control module 1 is further used for:

[0084] Set multiple voltage intervals with the same voltage change amplitude;

[0085] The voltage interval corresponding to the voltage with the smallest voltage mean is taken as the charging voltage interval;

[0086] When the DC voltage value output by the rectifier module enters the charging voltage interval, the PFC switch tube Q is controlled to be turned on; when the maximum value of the charging voltage interval is reached, the PFC switch tube Q is controlled to be turned off, and the voltage interval adjacent to the current charging voltage interval is determined as the charging voltage interval until the bus capacitor voltage reaches the maximum voltage.

[0087] In this embodiment, the maximum voltage is Among them, U is the effective value of the voltage of the input AC power supply.

[0088] In this embodiment, the input AC power supply generates direct current through a rectification module, and the sampled value V of the direct current is obtained by resistor voltage division (resistors R 1 , R 2 ); an inductor L, a switching transistor Q, and a capacitor C form a boost circuit; relays K in ; relays K 1 , K 2 , K 3 are used to control the entire circuit to work between the boost state and the bus voltage soft start state; the MCU controller generates a switching signal to respectively control the switching states of relays K 1 , K 2 , K 3 .

[0089] When relays K 1 , K 2 , K 3 are all open, the entire circuit is in an open state, denoted as the initial state; when relays K 1 , K 2 are open and K 3 is closed, the power supply charges the bus capacitor C through the inductor L, the switching transistor Q, and the relay K 3 , and the circuit works in the bus voltage soft start charging state; when relays K 1 , K 2 are closed and K 3 is open, the switching transistor Q is connected in parallel with the bus capacitor C to form a boost circuit, and the circuit works in the PFC boost state.

[0090] When just powered on, relays K 1 , K 2 , K 3 are all open. After the system receives a working instruction, the bus capacitor needs to start charging. At this time, the MCU control unit processes and judges the sampled signal of the input DC voltage, and divides the input DC voltage V in from (where U is the effective value of the voltage of the input AC power supply) into k (k >= 1) segments with the same voltage change in sequence, and defines the interval It should be noted that the larger k is, the better the soft start effect is, and those skilled in the art can set the value of k according to time requirements.

[0091] When the MCU detects that V in is located in the nth interval , the MCU controls the switching transistor Q to be in the on state, and in other cases, it is in the off state. This is repeated for several cycles to ensure that the bus voltage is charged to This continues until the MCU completes V in In all intervals of control, the bus voltage will rise accordingly

[0092] Taking 220V AC input voltage as an example, ideally, after rectification, the sampled DC voltage peak value V in The range is between 0V and 311V. According to the formula: It can be known that for the same time change Δt, the smaller the voltage change Δu is, or for the same voltage change Δu, the larger the time change Δt is, the smaller the current i will be.

[0093] Take dividing the interval into 3 segments as an example, Figure 3 As shown, the DC voltage peak is V dc ,zThe input cycle is T, the switch tube opening time and bus voltage waveform refer to Figure 3 , the switch tube is turned on in interval 1 from the initial voltage waveform of the bus voltage to the voltage value of the waveform reaching 103V, after which the switch tube is controlled to be turned off. When the voltage value corresponding to the bus voltage waveform drops back to 103V, the switch tube is controlled to be turned on again. The specific control method is as follows: After the system receives the working instruction, the input DC voltage V in The voltage range from 0V to 311V is divided into three sections, namely, section 1 [0V to 103V], section 2 [103V to 206V], and section 3 [206V to 311V]. The MCU detects the DC voltage V in When the voltage is in interval 1 [0V~103V], the MCU controls the switch tube Q to be in the on state, and in the off state at other times. This is repeated for several cycles to ensure that the bus voltage is charged to 103V. Next, the MCU detects the DC input voltage V in When the voltage is in interval 2 [103V~206V], the MCU controls the switch tube Q to be in the on state, and in the off state at other times. This is repeated for several cycles to ensure that the bus voltage is charged to 206V. Finally, the MCU detects the DC input voltage V in When it is in interval 3 [206V~311V], the MCU controls the switch tube Q to be in the on state, and in the off state at other times, and repeats this for several cycles to ensure that the bus voltage is charged to 311V, at which time the bus voltage will rise to 311V accordingly; then the MCU controls the relay to work in state three, and the entire bus voltage soft start process is completed. This process is smoother than the traditional bus voltage start-up using resistor buffering. In this way, the bus voltage is controllable throughout the soft start process, and the opening and closing of the controllable switch tube are controlled by synchronously collecting the input voltage value, so that the bus voltage is raised steadily, the impact current in the charging process of the traditional charging circuit is reduced, and the reliability and service life of electronic components are improved.

[0094] In this embodiment, by sampling the peak value of the input voltage passing through the rectification module in real time, the working state of the controllable switch tube of the PFC is controlled by a relay, so that it switches between the soft start working state and the boost state of the DC bus voltage. When working in the soft start state of the bus voltage, by detecting the DC voltage value at the back end of the rectifier bridge in real time, the MCU controls the switch tube to conduct starting from the lowest point of the DC voltage peak, and gradually changes to conduct when the DC voltage reaches the highest point. During the process, the on and off moments of the switch tube and the on duration are adjusted in real time and accurately, effectively controlling the charging current during bus charging, reducing the impact on the components at the back end of the circuit, increasing the startup reliability of the air conditioner, and extending the service life of the air conditioner; at the same time, multiple cement resistors are omitted, effectively saving space and reducing costs.

[0095] Figure 4 It is a flowchart of the soft start control method provided by an embodiment of the present application. As Figure 3 shown, the soft start control method includes:

[0096] S41: Collect the DC voltage value in the soft start circuit;

[0097] In this embodiment, collecting the DC voltage value in the soft start circuit includes:

[0098] S411: Divide the DC voltage output by the rectification module in the soft start circuit;

[0099] S412: Collect the DC voltage value on the voltage dividing resistor;

[0100] S413: Calculate the DC voltage value in the soft start circuit according to the DC voltage value on the voltage dividing resistor.

[0101] S42: Control the connection relationship between the PFC switch tube and the bus capacitor according to the DC voltage value in the soft start circuit. When the PFC switch tube is in series with the bus capacitor, charge the bus capacitor, and the bus capacitor enters the soft start working state; when the PFC switch tube is in parallel with the bus capacitor, boost the bus capacitor, and the bus capacitor enters the boost working state.

[0102] In this embodiment, controlling the working state of the PFC switch tube according to the DC voltage value in the soft start circuit includes:

[0103] S421: Set multiple voltage intervals with the same voltage change amplitude;

[0104] S422: Use the voltage interval with the smallest average voltage corresponding to the voltage interval as the charging voltage interval;

[0105] S423: When the DC voltage value in the soft start circuit enters the charging voltage range, control the PFC switch tube to conduct;

[0106] S424: When reaching the maximum value of the charging voltage range, control the PFC switch tube to cut off, and determine the voltage range adjacent to the current charging voltage range as the charging voltage range until the bus capacitor voltage reaches the maximum voltage value.

[0107] As Figure 5 shown, when just powered on, the relays K 1 , K 2 , K 3 are all off. After the system receives the working instruction, the bus capacitor needs to start charging. At this time, the MCU control unit processes and judges the sampling signal of the input DC voltage, and divides the input DC voltage V in from (where U is the effective value of the voltage of the input AC power supply) into k (k >= 1) segments with the same voltage change in sequence, and defines the interval It should be noted that the larger k is, the better the soft start effect is. Those skilled in the art can set the value of k according to the time requirement.

[0108] When the MCU detects that V in is located in the nth interval , the MCU controls the switch tube Q to be in the on state, and in other times it is in the off state. Repeating this for several cycles, ensuring that the bus voltage is charged to Going on like this, until the MCU completes the control of V in in all intervals at one time, at this time the bus voltage will rise correspondingly to

[0109] It should be noted that this application is applicable to the rectification-boost circuit and is applicable to scenarios with bus charging requirements.

[0110] In this embodiment, by sampling the peak value of the input voltage passing through the rectification module in real time, using the relay to control the working state of the controllable switch tube of the PFC, enabling it to switch between the soft start state and the boost state of the DC bus voltage. When working in the soft start state of the bus voltage, by detecting the DC voltage value at the rear end of the rectifier bridge in real time, the MCU controls the switch tube to conduct starting from the lowest point of the DC voltage peak, gradually changing to conduct when the DC voltage reaches the highest point. During the process, the opening and closing moments of the switch tube and the duration of conduction are adjusted in real time and accurately, effectively controlling the charging current during bus charging, reducing the impact on the components at the rear end of the circuit, increasing the startup reliability of the air conditioner, and extending the service life of the air conditioner; at the same time, multiple cement resistors are omitted, effectively saving space and reducing costs.

[0111] An embodiment of the present invention provides a controller, including: the soft start circuit as described in the above embodiment.

[0112] An embodiment of the present invention further provides an air conditioner, including: the controller as described in the above embodiment.

[0113] It can be understood that the same or similar parts in the above embodiments can be referred to each other, and the content not described in detail in some embodiments can be referred to the same or similar content in other embodiments.

[0114] It should be noted that in the description of the present application, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In addition, in the description of the present application, unless otherwise specified, the meaning of "a plurality of" refers to at least two.

[0115] Any process or method description in the flowchart or described in other ways herein can be understood as representing a module, segment, or part of executable instructions including one or more steps for implementing a specific logical function or process, and the scope of the preferred embodiments of the present application includes additional implementations, where the functions can be executed in a substantially simultaneous manner or in the reverse order according to the involved functions, rather than in the order shown or discussed, which should be understood by those skilled in the art to which the embodiments of the present application belong.

[0116] It should be understood that each part of the present application can be implemented by hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, any one or a combination of the following well-known technologies in the art can be used: discrete logic circuits with logic gate circuits for implementing logical functions on data signals, application-specific integrated circuits with appropriate combinational logic gate circuits, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0117] Those of ordinary skill in the art of this technology can understand that all or part of the steps carried by the methods of the above embodiments can be completed by instructing relevant hardware through a program, and the program can be stored in a computer-readable storage medium. When the program is executed, it includes one or a combination of the steps of the method embodiments.

[0118] In addition, each functional unit in various embodiments of the present application may be integrated into one processing module, may exist physically alone for each unit, or two or more units may be integrated into one module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. When the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

[0119] The above-mentioned storage medium may be a read-only memory, a magnetic disk, an optical disc, or the like.

[0120] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0121] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present application. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present application.

[0122] It should be noted that the present invention is not limited to the above-mentioned best mode. Those skilled in the art can obtain various other forms of products under the inspiration of the present invention. However, no matter what changes are made in its shape or structure, as long as it has a technical solution identical or similar to that of the present application, it falls within the protection scope of the present invention.

Claims

1. A soft start circuit, characterized in that, it includes: a control module, a circuit switching module, a rectification module, a PFC switch tube and a bus capacitor; the input end of the rectification module is connected to an input AC power supply; the output end of the rectification module is connected to the PFC switch tube; the control module switches the connection relationship between the PFC switch tube and the bus capacitor through the circuit switching module. When the PFC switch tube is connected in series with the bus capacitor, the bus capacitor is charged, and the bus capacitor enters the soft start working state; when the PFC switch tube is connected in parallel with the bus capacitor, the bus capacitor is boosted, and the bus capacitor enters the boosting working state; it further includes: a PFC inductor, which is arranged between the positive output end of the rectification module and the positive pole of the bus capacitor, and is used to charge or boost the bus capacitor; wherein, one end of the PFC switch tube is connected to the output end of the PFC inductor, and the other end of the PFC switch tube is connected to the bus capacitor.

2. The soft start circuit according to claim 1, characterized in that, the circuit switching module includes: a first switch, a second switch and a third switch; the first switch is arranged between the emitter of the PFC switch tube and the positive pole of the bus capacitor; the second switch is arranged between the collector of the PFC switch tube and the negative pole of the bus capacitor; the third switch is arranged between the collector of the PFC switch tube and the positive pole of the bus capacitor.

3. The soft start circuit according to claim 2, characterized in that, the control module switches the connection relationship between the PFC switch tube and the bus capacitor through the circuit switching module, including: the control module controls the first switch and the second switch to be closed and the third switch to be open, so as to control the PFC switch tube to be connected in parallel with the bus capacitor; the control module controls the first switch and the second switch to be open and the third switch to be closed, so as to control the PFC switch tube to be connected in series with the bus capacitor.

4. The soft start circuit according to claim 2 or 3, characterized in that, the first switch, the second switch or the third switch is at least one of a relay, a circuit breaker, a contactor, and a controllable semiconductor device.

5. The soft start circuit according to claim 1, characterized in that, it further includes: a voltage sampling module, which is connected to the rectification module; the voltage sampling module includes a first resistor and a second resistor, and the resistance value of the first resistor is greater than that of the second resistor; the first resistor and the second resistor are used to divide the DC voltage output by the rectification module; the voltage sampling module is used to collect the DC voltage value on the second resistor; the control module is further used to calculate the DC voltage value output by the rectification module according to the DC voltage value on the second resistor collected by the voltage sampling module.

6. The soft start circuit according to claim 5, characterized in that, the control module is further used to: set multiple voltage intervals with the same voltage change amplitude; Use the voltage range with the minimum average voltage corresponding to the voltage range as the charging voltage range; When the DC voltage value output by the rectification module enters the charging voltage range, control the PFC switch tube to conduct; When reaching the maximum value of the charging voltage range, control the PFC switch tube to cut off, and determine the voltage range adjacent to the current charging voltage range as the charging voltage range until the bus capacitor voltage reaches the maximum voltage value.

7. The soft start circuit according to claim 5 or 6, characterized in that, The maximum value of the DC voltage is UV, where U is the effective value of the voltage of the input AC power supply.

8. A soft start control method, characterized in that, applied to the soft start circuit according to any one of claims 1-7, the method includes: Collect the DC voltage value in the soft start circuit; Control the connection relationship between the PFC switch tube and the bus capacitor according to the DC voltage value in the soft start circuit. When the PFC switch tube is connected in series with the bus capacitor, charge the bus capacitor, and the bus capacitor enters the soft start working state; when the PFC switch tube is connected in parallel with the bus capacitor, boost the bus capacitor, and the bus capacitor enters the boost working state.

9. The soft start control method according to claim 8, characterized in that, The collecting the DC voltage value in the soft start circuit includes: Dividing the DC voltage output by the rectification module in the soft start circuit; Collect the DC voltage value on the voltage dividing resistor; Calculate the DC voltage value in the soft start circuit according to the DC voltage value on the voltage dividing resistor.

10. The soft start control method according to claim 8 or 9, characterized in that, The controlling the connection relationship between the PFC switch tube and the bus capacitor according to the DC voltage value in the soft start circuit includes: Set multiple voltage ranges with the same voltage change amplitude; Use the voltage range with the minimum average voltage corresponding to the voltage range as the charging voltage range; When the DC voltage value in the soft start circuit enters the charging voltage range, control the PFC switch tube to conduct; When reaching the maximum value of the charging voltage range, control the PFC switch tube to cut off, and determine the voltage range adjacent to the current charging voltage range as the charging voltage range until the bus capacitor voltage reaches the maximum voltage value.

11. A controller, characterized in that, includes: The soft start circuit according to any one of claims 1-7.

12. An air conditioner, characterized in that, includes: The controller according to claim 11.

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