Air conditioner boost circuit, circuit board and air conditioner

Abstract

The application discloses an air conditioner boost circuit, a circuit board and an air conditioner, relates to the technical field of circuits, and comprises a control module, a common mode inductor, a rectifier module and a charge-discharge module connected in sequence; the charge-discharge module comprises a first switch tube connected with an output end of the rectifier module, a first diode connected with the first switch tube and a first capacitor connected with the first diode; the control module is connected with a control pin of the first switch tube and is configured to determine a duty cycle of a PWM signal output to the control pin of the first switch tube according to an input voltage of an alternating power source accessed by the common mode inductor and an output target voltage and control a turn-off duration of the first switch tube according to an inductance current of the common mode inductor. The application can realize the soft switch control without using a boost inductor and with zero turn-on loss, thereby improving the efficiency of the air conditioner boost circuit.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of circuit, in particular to an air conditioner boost circuit, a circuit board and an air conditioner. BACKGROUND

[0002] At present, the existing boost circuit needs to design an independent energy storage inductor to realize boost, and the PFC control method basically adopts the hard-off mode to realize the closing of the switch tube. Therefore, the boost circuit of the existing scheme needs a larger circuit board area, and the electric control cost is higher; the switching loss of the switch tube is large, and it is difficult to realize high-efficiency PFC. SUMMARY

[0003] The present application aims to at least solve one of the problems in the prior art, and provides an air conditioner boost circuit, a circuit board and an air conditioner, which can realize the use of boost inductor and realize zero switching loss soft switch control, and improve the efficiency of the air conditioner boost circuit.

[0004] In a first aspect, the present application provides an air conditioner boost circuit, comprising a control module and a common mode inductor, a rectifier module and a charge-discharge module connected in sequence, wherein:

[0005] The charge-discharge module comprises a first switch tube connected with the output end of the rectifier module, a first diode connected with the first switch tube, and a first capacitor connected with the first diode;

[0006] The control module is connected with the control pin of the first switch tube, and is configured to determine the duty cycle of the PWM signal output to the control pin of the first switch tube according to the input voltage and the output target voltage of the alternating current power source connected with the common mode inductor, and control the off duration of the first switch tube according to the inductance current of the common mode inductor.

[0007] The air conditioner boost circuit provided by the embodiment of the present application has at least the following beneficial effects: the leakage inductance in the common-mode inductor is used as the energy storage inductor in the boost circuit to realize normal operation of the circuit boost, so that the boost inductor is not used, the device is saved, the resource use is reduced, and the circuit cost is reduced; after the first switch tube in the charge-discharge module is turned on, the common-mode inductor stores energy; after the first switch tube is turned off, the inductance current of the common-mode inductor flows through the first diode to provide a low-impedance loop for the energy released by the common-mode inductor; after the energy of the common-mode inductor is released, the junction capacitor voltage of the rectifier module is loaded on both ends of the common-mode inductor, so that the inductance current of the common-mode inductor flows reversely, and when the junction capacitor voltage of the rectifier module is equal to the voltage of the input alternating current power supply, the common-mode inductor releases the charge of the junction capacitor through the freewheeling effect, so that the first switch tube can be turned on with zero voltage and zero current, and therefore, the duration of the turn-off of the first switch tube can be controlled according to the inductance current of the common-mode inductor, so that the soft switching control of zero turn-on loss is realized, and the efficiency of the air conditioner boost circuit is improved.

[0008] The air conditioner boost circuit provided by some embodiments of the present application uses a rectifier bridge device or is composed of four diodes.

[0009] The reverse recovery time of the diode chip in the rectifier bridge device or the four diodes is greater than 1 μS, and the junction capacitance is greater than 100 pF.

[0010] The reverse recovery time of the diode chip in the rectifier bridge device or the four diodes is less than 1 μS, and the junction capacitance is less than 100 pF, and the charge-discharge module further includes a second capacitor, and the two ends of the second capacitor are respectively connected to the positive output end and the negative output end of the rectifier module.

[0011] The duty cycle of the PWM signal is calculated by the following formula:

[0012] ;

[0013] wherein D is the duty cycle, Vout is the output target voltage, Vin is the input voltage of the alternating current power supply.

[0014] The duration of the turn-off of the first switch tube is equal to the sum of the first duration and the second duration; wherein the first duration is the duration during which the inductance current of the common-mode inductor decreases to zero after the first switch tube is turned off; and the second duration is the duration during which the inductance current flows reversely and returns to zero.

[0015] According to the air conditioner boost circuit provided by some embodiments of the present application, when the first switch tube is off and the inductance current of the common-mode inductor decreases to zero, or when the inductance current starts to flow reversely, the voltage between the two switch pins of the first switch tube starts to decrease; when the inductance current flows reversely and returns to zero, the voltage between the two switch pins of the first switch tube decreases to zero.

[0016] According to the air conditioner boost circuit provided by some embodiments of the present application, after the first switch tube is off, when it is detected that the inductance current flows reversely and returns to zero or that the voltage between the two switch pins of the first switch tube decreases to zero, the control module controls the first switch tube to be on.

[0017] According to the air conditioner boost circuit provided by some embodiments of the present application, the first time length is calculated by the following formula:

[0018] ;

[0019] Wherein, T1 is the first time length, L1 is the inductance of the common-mode inductor L1, I1 is the inductance sampling current of the common-mode inductor L1, is the output target voltage, is the AC power supply;

[0020] The inductance of the common-mode inductor is calculated by the following formula:

[0021] ;

[0022] is the time difference between the sampling time of the inductance sampling current of the common-mode inductor and the opening time of the first switch tube.

[0023] According to the air conditioner boost circuit provided by some embodiments of the present application, the second time length is calculated by the following formula:

[0024] ;

[0025] Wherein, Cds is the sum of the capacitance of the parasitic capacitance between the two switch pins of the first switch tube and the capacitance of the junction capacitance of the two diodes in the rectifier module.

[0026] According to the air conditioner boost circuit provided by some embodiments of the present application, after the first switch tube is off, when it is detected that the off duration of the first switch tube reaches the sum of the first time length and the second time length, the control module controls the first switch tube to be on.

[0027] According to some embodiments of the present application, the common mode inductor comprises a magnetic ring and a coil wound on the magnetic ring; the common mode inductor further comprises an insulating shell wrapping the magnetic ring or an insulating material wound between the magnetic ring and the coil to increase the distance between the magnetic ring and the coil.

[0028] According to some embodiments of the present application, the common mode inductor is coated with magnetic powder or magnetic conductive material on the outside.

[0029] According to some embodiments of the present application, the air conditioner boost circuit further comprises a first absorption inductor, two ends of the first absorption inductor being connected to the first end and the second end of the common mode inductor respectively.

[0030] In a second aspect, the present application provides a circuit board comprising the air conditioner boost circuit according to the first aspect.

[0031] In a third aspect, the present application provides an air conditioner comprising the air conditioner boost circuit according to the first aspect or the circuit board according to the second aspect.

[0032] Other features and advantages of the present application will be further described in the following description with reference to the drawings, and will be apparent from the description, or will be learned from the practice of the application. The objects and other advantages of the present application will be realized and attained by the structure particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF DRAWINGS

[0033] The accompanying drawings, which are included to provide a further understanding of the technology scheme of the present application, constitute a part of the specification and are used together with the embodiments of the present application to explain the technology scheme of the present application, and do not constitute a limitation on the technology scheme of the present application.

[0034] The present application will be further described below with reference to the drawings and embodiments.

[0035] Figure 1 is a circuit schematic diagram of the air conditioner boost circuit according to the first embodiment of the present application;

[0036] Figure 2 is a circuit schematic diagram of the air conditioner boost circuit according to the second embodiment of the present application;

[0037] Figure 3 is a circuit schematic diagram of the air conditioner boost circuit according to the third embodiment of the present application;

[0038] Figure 4 is a control timing diagram of the air conditioner boost circuit according to the present application;

[0039] Figure 5is a schematic diagram of a zero-voltage detection circuit of an air conditioner boost circuit provided by the fourth embodiment of the present application;

[0040] Figure 6 is a schematic diagram of a zero-voltage detection circuit of an air conditioner boost circuit provided by the fifth embodiment of the present application;

[0041] Figure 7 is a schematic diagram of a current sampling circuit and a zero-current detection circuit of an air conditioner boost circuit provided by the sixth embodiment of the present application;

[0042] Figure 8 is a control flow chart of an air conditioner boost circuit using hardware control provided by the embodiment of the present application;

[0043] Figure 9 is a flow chart of a pure software control method of an air conditioner boost circuit provided by the embodiment of the present application. DETAILED DESCRIPTION

[0044] This part will describe the specific embodiments of the present application in detail, and the preferred embodiments of the present application are shown in the accompanying drawings, which serve to supplement the description of the text part and enable people to intuitively and visually understand each technical feature and the overall technical scheme of the present application, but it cannot be understood as a limitation on the protection scope of the present application.

[0045] In the description of the embodiments of the present application, one or more is meant to be one or more, more than two is meant to be two or more, greater than, less than, more than, etc. are understood as not including the number, above, below, within, etc. are understood as including the number, "at least one" means one or more, "at least one of the following" and the like means any combination of these items, including single or multiple items. If there is a description of "first", "second", etc., it is only used to distinguish technical features for the purpose, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of indicated technical features or implicitly indicating the sequence of indicated technical features.

[0046] It should be noted that the terms such as setting, installing and connecting in the embodiments of the present application should be understood broadly, and the skilled in the art can determine the specific meaning of the above terms in the embodiments of the present application in combination with the specific content of the technical scheme. For example, the term "connection" can be mechanical connection, electrical connection or can communicate with each other; it can be directly connected, or indirectly connected through an intermediate medium.

[0047] It should be noted that the technical features involved in each embodiment of the present application described below can be combined with each other as long as there is no conflict between them.

[0048] At present, the existing boost circuit needs to design a separate energy storage inductor to realize boost. In addition, the existing PFC control method basically adopts the hard-off mode to realize the closing of the switch tube, and some data describes that the CRM or DCM mode is used to realize ZCS zero-current closing. Therefore, the existing high-speed flower boost circuit scheme using a separate energy storage inductor to realize boost needs a larger circuit board area and has a high electrical control cost; the control method using hard-off has a simple control mode, but cannot realize zero-voltage and zero-current closing, the switching loss of the switch tube is large, and it is difficult to realize high-efficiency PFC; in addition, the control method using CRM or DCM mode can only realize zero-current closing, and cannot realize zero-voltage and zero-current closing at the same time, and still has certain closing loss.

[0049] Based on this, the embodiment of the present application provides an air conditioner boost circuit, a circuit board and an air conditioner, which can realize the use of a boost inductor and realize soft switching control of zero turn-on loss, and improve the efficiency of the air conditioner boost circuit.

[0050] The embodiment of the present application will be further described below with reference to the drawings.

[0051] Figure 1 is the circuit principle diagram of the air conditioner boost circuit provided by the first embodiment of the present application; Figure 2 is the circuit principle diagram of the air conditioner boost circuit provided by the second embodiment of the present application. Referring to Figure 1 or Figure 2 , the first aspect embodiment of the present application provides an air conditioner boost circuit, which comprises a common mode inductor L1, a rectifier module 100, a charge-discharge module 200 and a control module 300.

[0052] The common mode inductor L1, the rectifier module 100 and the charge-discharge module 200 are connected in sequence. Specifically, the first end and the second end of the common mode inductor L1 are connected to an alternating current power supply; the alternating current power supply comprises a live wire input end Lin and a neutral wire input end Nin, the first end of the common mode inductor L1 is connected to the live wire input end Lin of the alternating current power supply, and the second end of the common mode inductor L1 is connected to the neutral wire input end Nin of the alternating current power supply.

[0053] Referring to Figure 1 and Figure 2 , the air conditioner boost circuit can further comprise a first absorption inductor CX1, and the two ends of the first absorption inductor CX1 are respectively connected to the first end and the second end of the common mode inductor L1. It can be understood that the common mode inductor L1 and the first absorption inductor CX1 combine to form an EMC module of the air conditioner boost circuit, which is used to reduce the electromagnetic radiation of the air conditioner boost circuit.

[0054] The input end of the rectifier module 100 is connected to the third end and the fourth end of the common mode inductor L1.

[0055] The charge-discharge module 200 comprises a first switch tube Q1, a first diode D1 and a first capacitor C1, the positive output terminal of the rectifier module 100 is connected to one switch pin of the first switch tube Q1 and the anode of the first diode D1, the cathode of the first diode D1 is connected to one end of the first capacitor C1, and the negative output terminal of the rectifier module 100 is connected to another switch pin of the first switch tube Q1 and the other end of the first capacitor C1.

[0056] One output terminal of the control module 300 is connected to the control pin of the first switch tube Q1, the control module 300 is used for outputting a PWM signal to the control pin of the first switch tube Q1 to control the conduction and turn-off of the first switch tube Q1, the duty cycle of the PWM signal is determined according to the input voltage of the alternating current power supply and the output target voltage, and the turn-off duration of the first switch tube Q1 is controlled according to the inductance current of the common-mode inductor L1.

[0057] According to the air conditioner boost circuit provided in the embodiments of the present application, the leakage inductance in the common-mode inductor L1 is used as the energy storage inductance in the boost circuit to realize the normal operation of the circuit boost, the boost inductance is not used, the device is saved, the resource use is reduced, and thus the circuit cost is reduced; after the first switch tube Q1 in the charge-discharge module 200 is turned on, the common-mode inductor L1 stores energy; after the first switch tube Q1 is turned off, the inductance current of the common-mode inductor L1 flows through the first diode D1 to provide a low-impedance loop for the energy released by the common-mode inductor L1; after the energy of the common-mode inductor L1 is released, the junction capacitor voltage of the rectifier module 100 is loaded on both ends of the common-mode inductor L1 to realize the reverse flow of the inductance current of the common-mode inductor L1; when the junction capacitor voltage of the rectifier module 100 is equal to the voltage of the input alternating current power supply, the common-mode inductor L1 realizes the release of the junction capacitor charge through the freewheeling effect, and the zero-voltage and zero-current turn-on of the first switch tube Q1 can be realized, so that the turn-off duration of the first switch tube Q1 is controlled according to the inductance current of the common-mode inductor L1, the soft switching control of the zero turn-on loss can be realized, and the efficiency of the air conditioner boost circuit is improved.

[0058] In the air conditioner boost circuit provided in some embodiments of the present application, the rectifier module 100 can use a rectifier bridge device BR1, for example, as shown in Figure 1 .

[0059] In the air conditioner boost circuit provided in some other embodiments of the present application, the rectifier module 100 can also be composed of four diodes, for example, as shown in Figure 2As shown, the rectifier module 100 includes a second diode D2, a third diode D3, a fourth diode D4 and a fifth diode D5, the third end of the common-mode inductor L1 is connected to the anode of the second diode D2 and the cathode of the fourth diode D4, the fourth end of the common-mode inductor L1 is connected to the anode of the third diode D3 and the cathode of the fifth diode D5, the cathode of the second diode D2 and the cathode of the third diode D3 are connected together as the positive output terminal of the rectifier module 100 and connected to one of the switching pins of the first switch tube Q1 and the anode of the first diode D1, the anode of the fourth diode D4 and the anode of the fifth diode D5 are connected together as the negative output terminal of the rectifier module 100 and connected to the other of the switching pins of the first switch tube Q1.

[0060] In the air conditioner boost circuit provided by some embodiments of the present application, the common-mode inductor L1 includes a magnetic ring and a coil wound on the magnetic ring, wherein the magnetic ring can be a ring-shaped magnetic ring or a rectangular magnetic ring. In addition, the common-mode inductor L1 further includes an insulating shell wrapping the magnetic ring or an insulating material wound between the magnetic ring and the coil to increase the distance between the magnetic ring and the coil. It can be understood that different distances between the magnetic ring and the coil can result in different leakage inductances of the common-mode inductor L1. For the common-mode inductor L1 with a rectangular magnetic ring, since the coil wire is wound only on the magnetic columns on two sides of the magnetic ring, and the magnetic path between the magnetic columns on two sides of the magnetic ring is far, a larger leakage inductance can be generated, and thus the leakage inductance of the common-mode inductor L1 can be controlled by controlling the coupling coefficient of the coils on two sides.

[0061] Since the leakage inductance of the common-mode inductor L1 is generated by the self-coupling of most magnetic fields through the air, the common-mode inductor L1 can generate a large interference to the circuit when the air conditioner boost circuit works. In order to solve this problem, in the air conditioner boost circuit provided by some embodiments of the present application, the outside of the common-mode inductor L1 is coated with magnetic powder or magnetic conductive material to guide or shield the leakage magnetic field of the common-mode inductor L1, thereby solving the problem that the common-mode inductor L1 can generate a large interference to the circuit. Similarly, the common-mode inductor L1 can also use an additional shielding shell, shielding sponge and the like to achieve this purpose. In addition, the common-mode inductor L1 can also be installed far away from the circuit board to solve the problem that the common-mode inductor L1 can generate a large interference to the circuit.

[0062] For the air conditioner boost circuit in Figure 1 and Figure 2 , CCM, CRM and DCM modes can be used for control, but these control modes do not have long-term reliability or can only operate at low efficiency. The soft switching control method provided by the embodiments of the present application can be used for Figure 1 In the air conditioner boost circuit provided by the embodiments of the present application, the reverse recovery time of the diode chip in the rectifier bridge device BR1 is greater than 1 μS, and the junction capacitance is greater than 100 pF; in Figure 2In the air conditioner boost circuit provided in the embodiment, the reverse recovery time of the four diodes, namely the second diode D2, the third diode D3, the fourth diode D4 and the fifth diode D5, is greater than 1μS, and the junction capacitance is greater than 100pF. After the first switch tube Q1 is turned off, the junction capacitance in the rectifier module 100 stores energy during the freewheeling process of the inductor current of the common-mode inductor L1. After the energy of the common-mode inductor L1 is released, the two ends of the diode junction capacitance of the rectifier module 100 (such as Figure 2 , when the live input terminal Lin is positive and the neutral input terminal Nin is negative, the voltage UD across the fourth diode D4 and the third diode D3 is equal to the output voltage Uout. Therefore, after the inductive energy is released, the voltage UD across the diode junction capacitance of the rectifier module 100 will be loaded on the common-mode inductor L1, realizing the reverse flow of the inductive current of the common-mode inductor L1. When the voltage across the junction capacitance is equal to the input voltage, the common-mode inductor L1 realizes the charge release of the diode junction capacitance of the rectifier module 100 through the freewheeling effect, thereby realizing the zero voltage and zero current turn-on of the first switch tube Q1, thereby realizing soft switching control with zero turn-on loss. Specifically, referring to Figure 4 As shown, Figure 4 The curve corresponding to the vertical coordinate Q1 in represents the PWM signal output to the control pin of the first switch tube Q1 and can also represent the on / off state of the first switch tube Q1; Figure 4 The curve corresponding to the vertical coordinate I1 in represents the inductor current signal of the common-mode inductor L1; Figure 4 The curve corresponding to the vertical coordinate “Vds of Q1” in FIG. 1 represents the voltage signal between the two switch pins of the first switch tube Q1 ;

[0063] At time t1, the first switch tube Q1 is turned on, and the common mode inductor L1 stores energy; the control module 300 is based on the input voltage of the AC power supply. and output target voltage Calculate the duty cycle of the output PWM signal. The calculation formula for the duty cycle of the PWM signal is: ; thereby controlling the on-time of the first switch tube Q1; it should be noted that the duty cycle calculation formula calculates the difference between the output target voltage and the detected input voltage of the AC power supply, and then divides the difference by the output target voltage to obtain the duty cycle of the PWM signal. By using this duty cycle to control the on-time of the first switch tube Q1, the output voltage of the air conditioner boost circuit can be made close to or equal to the output target voltage;

[0064] At time t2, the first switch tube Q1 is turned off, and the inductor current I1 of the common-mode inductor L1 is freewheeling through the first diode D1, providing a low-impedance loop for the energy released by the common-mode inductor L1;

[0065] At the moment t3, the energy of the common-mode inductor L1 is released, and the inductive current I1 of the common-mode inductor L1 flows reversely and returns to zero; at this moment, the voltage UD between the junction capacitances of the diodes of the rectifier module 100 is higher than the input voltage of the AC power supply , and the inductive current I1 of the common-mode inductor L1 starts to flow reversely; the time length Td for the inductive current I1 of the common-mode inductor L1 to return to zero after flowing reversely is calculated by the formula , wherein Cds is the sum of the capacitance of the parasitic capacitance between the two switch pins of the first switch tube Q1 and the capacitance of the junction capacitances of the two diodes in the rectifier module 100 (such as the junction capacitance of the fourth diode D4 and the junction capacitance of the third diode D3), and L1 is the inductance of the common-mode inductor L1. It should be noted that the calculation formula of the time length Td is based on the circuit working principle of the air conditioner boost circuit shown in Figure 1 and is derived based on the analysis of various measured parameters of the circuit.

[0066] At the moment t4, the inductive current I1 of the common-mode inductor L1 completes the extraction of the capacitance of the parasitic capacitance between the two switch pins of the first switch tube Q1 (such as the drain and source of the MOS tube when the first switch tube Q1 is a MOS tube) and the charge of the two rectifier diode junction capacitances such as the junction capacitance of the fourth diode D4 + the junction capacitance of the third diode D3, that is, the discharge of the voltage across the first switch tube Q1.

[0067] In the air conditioner boost circuit provided in some embodiments of the present application, the diode crystal of the rectifier bridge device BR1 or the four diodes such as the second diode D2, the third diode D3, the fourth diode D4 and the fifth diode D5 can adopt a fast recovery diode, the reverse recovery time of which is less than 1 μS, and the diode junction capacitance is less than 100 pF, and accordingly with reference to Figure 3 , the charge and discharge module 200 further comprises a second capacitor C2, the two ends of the second capacitor C2 are connected to the positive output end and the negative output end of the rectifier module 100, that is, the second capacitor C2 is connected in parallel between the two switch pins of the first switch tube Q1, so as to realize the soft switching control function of the air conditioner boost circuit.

[0068] It can be understood that, with reference to Figure 4 , in the air conditioner boost circuit provided in some embodiments of the present application, the off duration of the first switch tube Q1 is equal to the sum of the first duration and the second duration; wherein: the first duration is the time length for the inductive current of the common-mode inductor L1 to drop to zero after the first switch tube Q1 is turned off, that is, the time length between the moment t2 and the moment t3 in Figure 4 ; the second duration is the time length for the inductive current to return to zero after flowing reversely, that is, the time length between the moment t3 and the moment t4 in Figure 4 .

[0069] Continuing to refer toFigure 4 In the air conditioner boost circuit provided by some embodiments of the present application, when the first switch tube Q1 is turned off and the inductive current I1 of the common-mode inductor L1 drops to zero, or when the inductive current I1 of the common-mode inductor L1 starts to flow reversely, the voltage between the two switch pins of the first switch tube Q1 starts to drop; when the inductive current I1 of the common-mode inductor L1 flows reversely and returns to zero, the voltage between the two switch pins of the first switch tube Q1 drops to zero.

[0070] It should be noted that the air conditioner boost circuit provided by the embodiments of the present application implements the soft switching control method, which can be realized by a hardware control mode or a software control mode.

[0071] When the soft switching control method is realized by the hardware control mode, the control module 300 needs to detect whether the inductive current I1 of the common-mode inductor L1 is zero or detect whether the voltage between the two switch pins of the first switch tube Q1 is zero. Specifically, the air conditioner boost circuit can realize the detection of the voltage between the two switch pins of the first switch tube Q1 by using the zero voltage detection circuit shown in Figure 5 or Figure 6 The air conditioner boost circuit can realize the detection of whether the inductive current I1 of the common-mode inductor L1 is zero by using the current sampling circuit and zero current detection circuit shown in Figure 7

[0072] Specifically, Figure 5 The air conditioner boost circuit shown in

[0073] In addition, Figure 6 ​The air conditioner boost circuit shown further comprises a third resistor R3, a fourth resistor R4, a third capacitor C3, a first comparator ICA1 and a second sampling resistor Rs2, the second sampling resistor Rs2 is connected between the negative output end of the rectifier module 100 and the switch pin of the first switch tube Q1, one end of the third resistor R3 is connected to the anode of the first diode D1, the other end of the third resistor R3, one end of the fourth resistor R4 and one end of the third capacitor C3 are all connected to the non-inverting input end of the first comparator ICA1; the other end of the fourth resistor R4 and the other end of the third capacitor C3 are connected to the connection point of the second sampling resistor Rs2 and the first switch tube Q1; the inverting input end of the first comparator ICA1 is connected to a reference voltage REF, and the output end of the first comparator ICA1 is connected to the input port of the control module 300, so that the output level change signal is given to the control module 300.

[0074] In addition, Figure 7 The air conditioner boost circuit shown further comprises a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, a second comparator ICA2, a third comparator ICA3 and a third sampling resistor Rs3, the third sampling resistor Rs3 is connected between the negative output end of the rectifier module 100 and the switch pin of the first switch tube Q1, the negative output end of the rectifier module 100 is further connected to the inverting input end of the second comparator ICA2 through the fifth resistor R5, the connection point of the third sampling resistor Rs3 and the first switch tube Q1 is connected to the non-inverting input end of the second comparator ICA2 through the sixth resistor R6, the two ends of the seventh resistor R7 are respectively connected to the inverting input end and the output end of the second comparator ICA2, the output end of the second comparator ICA2 is further connected to the non-inverting input end of the third comparator ICA3 and the input port of the control module 300, the inverting input end of the third comparator ICA3 is connected to a reference voltage REF, and the output end of the third comparator ICA3 is further connected to the input port of the control module 300, so that the output level change signal is given to the control module 300.

[0075] In the air conditioner boost circuit provided by some embodiments of the present application, referring to Figure 8 , the flow of realizing the soft switch control in the manner of hardware control is as follows:

[0076] The control module 300 first controls the first switch tube Q1 to be turned on;

[0077] The control module 300 then controls the first switch tube Q1 to be turned off;

[0078] After the first switch tube Q1 is turned off, when it is detected that the inductive current flows reversely and returns to zero or the voltage between the two switch pins of the first switch tube Q1 drops to zero, the control module 300 controls the first switch tube Q1 to be turned on.

[0079] In the present embodiment, theFigure 7 The current sampling circuit and zero current detection circuit shown, using a comparator to determine the inductor current, when the inductor current is lower than 0A (or close to 0A, such as 2A or less), the comparator device output flip output level change signal notification control module 300, control module 300 can use edge trigger into interrupt processing, so as to realize the control module 300 high efficiency, high reliability of zero current detection; similarly, when using Figure 5 Or Figure 6 The zero voltage detection circuit shown, the voltage between the two switch pins of the first switch tube Q1 is zero, through the control module 300 realizes the edge trigger.

[0080] In some embodiments of the application, the air conditioner boost circuit provided by the reference Figure 9 , the flow of the soft switch control realized by the pure software control method is:

[0081] The control module 300 controls the first switch tube Q1 to be turned on;

[0082] The inductance sampling current I1 of the common mode inductor L1 is collected in the opening, and the time difference between the sampling time of the inductance sampling current I1 of the common mode inductor L1 and the opening time of the first switch tube Q1 is recorded as ;

[0083] According to the input voltage of the alternating current power supply , the inductance sampling current I1 of the common mode inductor L1 collected, the time difference between the sampling time of the inductance sampling current I1 of the common mode inductor L1 and the opening time of the first switch tube Q1 The inductance L1 of the common mode inductor L1 is calculated, and the calculation formula is: ; It should be noted that the calculation formula of the inductance L1 of the common mode inductor L1 is based on Figure 1 The working principle of the air conditioner boost circuit shown and the analysis of various measurement parameters of the circuit.

[0084] The time length of the inductance current of the common mode inductor L1 after the first switch tube Q1 is turned off and the inductance current is reduced to zero is calculated, which is recorded as the first time length T1, and the calculation formula is: ; And calculate the time length of the inductance current of the common mode inductor L1 after the inductance current flows reversely and returns to zero, that is, the second time length Td, the calculation formula is: ; Cds is the sum of the capacitance of the parasitic capacitance between the two switch pins of the first switch tube Q1 and the capacitance of the junction capacitance of the two diodes in the rectifier module 100; and the turn-off time length of the first switch tube Q1 is calculated, that is, the third time length T3, the calculation formula is: T3=T1+Td; It should be noted that the calculation formula of the first time length T1 and the second time length Td is based on Figure 1The circuit working principle of the air conditioner boost circuit shown and obtained based on analysis of various measured parameters of the circuit is as follows:

[0085] The control module 300 controls the first switch tube Q1 to be turned off.

[0086] After the turn-off duration of the first switch tube Q1 reaches the third duration T3, the control module 300 controls the first switch tube Q1 to be turned on again.

[0087] In the embodiment, the leakage inductance in the common-mode inductor L1 is used as the energy storage inductor in the boost circuit to realize normal working of the circuit boost, so that the boost inductor is not used, the device is saved, the resource use is reduced, and thus the circuit cost is reduced. After the first switch tube Q1 in the charge-discharge module 200 is turned on, the common-mode inductor L1 stores energy. After the first switch tube Q1 is turned off, the inductance current of the common-mode inductor L1 flows through the first diode D1 to provide a low-impedance loop for the energy released by the common-mode inductor L1. After the energy of the common-mode inductor L1 is released, the junction capacitance voltage of the rectification module 100 is loaded on both ends of the common-mode inductor L1, so as to realize reverse flow of the inductance current of the common-mode inductor L1. When the junction capacitance voltage of the rectification module 100 is equal to the voltage of the input alternating current power supply, the common-mode inductor L1 releases the junction capacitance charge through the freewheeling effect, and the zero-voltage and zero-current turn-on of the first switch tube Q1 can be realized. Therefore, according to the duration of the turn-off of the first switch tube Q1 controlled based on the inductance current of the common-mode inductor L1, the soft switching control of zero turn-on loss can be realized, and the efficiency of the air conditioner boost circuit is improved.

[0088] In addition, the second aspect embodiment of the present application provides a circuit board comprising the air conditioner boost circuit of the first aspect embodiment.

[0089] In addition, the third aspect embodiment of the present application provides an air conditioner comprising the air conditioner boost circuit of the first aspect embodiment or the circuit board of the second aspect embodiment.

[0090] The embodiments of the present application are described in detail above in combination with the drawings, but the present application is not limited to the above-described embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the purpose of the present application.

Claims

1. An air conditioner boost circuit, characterized by comprising: The control module is connected with a common-mode inductor, a rectifier module and a charge-discharge module in sequence. The charge-discharge module comprises a first switch connected with the output end of the rectifier module, a first diode connected with the first switch and a first capacitor connected with the first diode. The control module is connected with a control pin of the first switch and is configured to determine a duty cycle of a PWM signal output to the control pin of the first switch according to an input voltage of an AC power source connected with the common-mode inductor and an output target voltage, and control a turn-off duration of the first switch according to an inductance current of the common-mode inductor. The turn-off duration of the first switch is equal to a sum of a first duration and a second duration, the first duration is a duration during which the inductance current of the common-mode inductor drops to zero after the first switch is turned off, and the second duration is a duration during which the inductance current returns to zero after the inductance current flows reversely.

2. The air conditioner boost circuit of claim 1, wherein, The rectifier module adopts a rectifier bridge device or is composed of four diodes.

3. The air conditioner boost circuit of claim 2, wherein, The reverse recovery time of a diode crystal of the rectifier bridge device or the four diodes is greater than 1 μS, and the junction capacitance is greater than 100 pF.

4. The air conditioner boost circuit of claim 2, wherein, The reverse recovery time of the diode crystal of the rectifier bridge device or the four diodes is less than 1 μS, and the junction capacitance is less than 100 pF, and the charge-discharge module further comprises a second capacitor, two ends of the second capacitor are connected with a positive output end and a negative output end of the rectifier module respectively.

5. The air conditioner boost circuit of claim 1, wherein, The duty cycle of the PWM signal is calculated by using the following formula: wherein: D is the duty cycle, Vout is the output target voltage, Vin is the input voltage of the AC power source.

6. The air conditioner boost circuit of claim 1, wherein When the first switch is turned off and the inductance current of the common-mode inductor drops to zero, or when the inductance current starts to flow reversely, a voltage between two switch pins of the first switch starts to drop; when the inductance current flows reversely and returns to zero, the voltage between the two switch pins of the first switch drops to zero.

7. The air conditioner boost circuit of claim 6, wherein After the first switch is turned off, when it is detected that the inductance current flows reversely and returns to zero or that the voltage between the two switch pins of the first switch drops to zero, the control module controls the first switch to be turned on.

8. The air conditioner boost circuit of claim 1, wherein The first duration is calculated by using the following formula: ； Wherein: T1 is the first duration, L1 is the inductance of the common mode inductor, I1 is the inductance sampling current of the common mode inductor, is the output target voltage, is the input voltage of the AC power supply; The inductance of the common-mode inductor is calculated by using the following formula: ； The time difference between the sampling time of the inductance sampling current of the common mode inductor and the opening time of the first switch tube.

9. The air conditioner boost circuit of claim 8, wherein, The second duration is calculated by using the following formula: Cds is a sum of a capacitance of a parasitic capacitance between the two switch pins of the first switch and a capacitance of a junction capacitance of two diodes in the rectifier module.

10. The air conditioner boost circuit of claim 9, wherein, After the first switch is turned off, when it is detected that the turn-off duration of the first switch reaches a sum of the first duration and the second duration, the control module controls the first switch to be turned on.

11. The air conditioner boost circuit of claim 1, wherein The common-mode inductor comprises a magnetic ring and a coil wound on the magnetic ring, and further comprises an insulating shell wrapping the magnetic ring or an insulating material wound between the magnetic ring and the coil to increase a distance between the magnetic ring and the coil.

12. The air conditioner boost circuit of claim 1, wherein, The common-mode inductor is coated with magnetic powder or magnetic conductive material.

13. The air conditioner boost circuit of claim 1, wherein The air conditioner boost circuit further comprises a first absorption inductor, two ends of the first absorption inductor being connected to the first end and the second end of the common-mode inductor respectively.

14. A wiring board, characterized by comprising: The air conditioner boost circuit comprises any one of claims 1 to 13.

15. An air conditioner characterized by comprising: The air conditioner boost circuit comprises any one of claims 1 to 13, or the circuit board of claim 14.

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