Air conditioner booster circuit, circuit board and air conditioner

Abstract

The invention discloses an air conditioner booster circuit, a circuit board and an air conditioner, and relates to the technical field of circuits, the air conditioner booster circuit comprises a control module, and a common mode inductor, a rectification module and a charging and discharging module which are connected in sequence; the charging and discharging module comprises a first switch tube connected with the output end of the rectification 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 the duty ratio of a PWM signal output to the control pin of the first switch tube according to the input voltage and the output target voltage of an AC power supply accessed by the common mode inductor, and controlling the turn-off duration of the first switching tube according to the inductive current of the common mode inductor. According to the invention, soft switching control without a boost inductor and zero switching loss can be realized, and the efficiency of the air conditioner boost circuit is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of circuits, and in particular, to an air conditioner boost circuit, a circuit board, and an air conditioner. Background Art

[0002] At present, existing boost circuits all need to design an independent energy storage inductor to achieve boosting, and the PFC control method basically adopts a hard turn-off method to turn off the switching tube. Therefore, the boost circuit of the existing solution requires a large circuit board area and has a high electronic control cost; the switching loss of the switching tube is large, and it is difficult to achieve high-efficiency PFC. Summary of the Invention

[0003] An object of the present invention is to at least solve one of the technical problems existing in the prior art, and to provide an air conditioner boost circuit, a circuit board, and an air conditioner, which can achieve the use of no boost inductor and realize soft-switching control with zero turn-on loss, thereby improving the efficiency of the air conditioner boost circuit.

[0004] In a first aspect, an embodiment of the present invention provides an air conditioner boost circuit, including a control module, and a common-mode inductor, a rectification module, and a charge and discharge module connected in sequence, wherein: The charge and discharge module includes a first switching tube connected to the output end of the rectification module, a first diode connected to the first switching tube, and a first capacitor connected to the first diode; The control module is connected to the control pin of the first switching tube and is configured to: determine the duty cycle of the PWM signal output to the control pin of the first switching tube according to the input voltage and the output target voltage of the AC power supply connected to the common-mode inductor, and control the turn-off duration of the first switching tube according to the inductor current of the common-mode inductor.

[0005] According to the air conditioner boost circuit provided by the embodiments of the present invention, it has at least the following beneficial effects: By using the leakage inductance in the common mode inductor as the energy storage inductor in the boost circuit to achieve the normal operation of circuit boosting, it is possible to achieve without using a boost inductor, saving devices, reducing resource usage, and thus reducing the circuit cost; after the first switch tube in the charge and discharge module is turned on, the common mode inductor stores energy; after the first switch tube is turned off, the inductor current of the common mode inductor continues to flow through the first diode, providing a low impedance loop for the energy released by the common mode inductor; after the energy release of the common mode inductor is completed, the junction capacitance voltage of the rectification module will be loaded at both ends of the common mode inductor, realizing the reverse flow of the inductor current of the common mode inductor. When the junction capacitance voltage of the rectification module is equal to the voltage of the input AC power supply, the common mode inductor realizes the release of the junction capacitance charge through the freewheeling effect, and the zero voltage and zero current turn-on of the first switch tube can be achieved. Therefore, by controlling the turn-off duration of the first switch tube according to the inductor current of the common mode inductor, the soft switch control with zero turn-on loss can be realized, and the efficiency of the air conditioner boost circuit can be improved.

[0006] According to the air conditioner boost circuit provided by some embodiments of the present invention, the rectification module uses a rectifier bridge device or is composed of four diodes.

[0007] According to the air conditioner boost circuit provided by some embodiments of the present invention, 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.

[0008] According to the air conditioner boost circuit provided by some embodiments of the present invention, 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. The charge and discharge module further includes a second capacitor, and both ends of the second capacitor are respectively connected to the positive output terminal and the negative output terminal of the rectification module.

[0009] According to the air conditioner boost circuit provided by some embodiments of the present invention, the duty cycle of the PWM signal is calculated using the following formula: ; where: D is the duty cycle, is the output target voltage, is the input voltage of the AC power supply.

[0010] According to the air conditioner boost circuit provided by some embodiments of the present invention, the turn-off duration of the first switch tube is equal to the sum of a first duration and a second duration; where: the first duration is the duration from when the first switch tube is turned off until the inductor current of the common mode inductor drops to zero; the second duration is the duration from when the inductor current flows reversely until it returns to zero.

[0011] According to the air conditioner boost circuit provided by some embodiments of the present invention, when the first switching tube is turned off and the inductance current of the common mode inductor drops to zero, or when the inductance current starts to flow reversely, the voltage between the two switching pins of the first switching tube starts to drop; when the inductance current flows reversely and returns to zero, the voltage between the two switching pins of the first switching tube drops to zero.

[0012] According to the air conditioner boost circuit provided by some embodiments of the present invention, after the first switching tube is turned off, when it is detected that the inductance current flows reversely and returns to zero or it is detected that the voltage between the two switching pins of the first switching tube drops to zero, the control module controls the first switching tube to conduct.

[0013] According to the air conditioner boost circuit provided by some embodiments of the present invention, the first duration is calculated by the following formula: ; where: T1 is the first duration, 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; The inductance of the common mode inductor is calculated by the following formula: ; is the time difference between the sampling time of the inductance sampling current of the common mode inductor and the turn-on time of the first switching tube.

[0014] According to the air conditioner boost circuit provided by some embodiments of the present invention, the second duration is calculated by the following formula: ; where: Cds is the sum of the capacitance of the parasitic capacitance between the two switching pins of the first switching tube and the junction capacitance of the two diodes in the rectification module.

[0015] According to the air conditioner boost circuit provided by some embodiments of the present invention, after the first switching tube is turned off, when it is detected that the turn-off duration of the first switching tube reaches the sum of the first duration and the second duration, the control module controls the first switching tube to conduct.

[0016] According to the air conditioner boost circuit provided by some embodiments of the present invention, the common mode inductor includes a magnetic core and a coil wound around the magnetic core; the common mode inductor further includes an insulating shell wrapping the magnetic core or an insulating material wound between the magnetic core and the coil to increase the distance between the magnetic core and the coil.

[0017] According to the air conditioner boost circuit provided by some embodiments of the present invention, the external of the common mode inductor is coated with magnetic powder or magnetic conductive material.

[0018] According to the air conditioner boost circuit provided by some embodiments of the present invention, the air conditioner boost circuit further includes a first absorption inductor, and two ends of the first absorption inductor are respectively connected to a first end and a second end of the common mode inductor.

[0019] In a second aspect, an embodiment of the present invention provides a circuit board, including the air conditioner boost circuit described in the first aspect embodiment above.

[0020] In a third aspect, an embodiment of the present invention provides an air conditioner, including the air conditioner boost circuit described in the first aspect embodiment above, or including the circuit board described in the second aspect embodiment above.

[0021] Other features and advantages of the present invention will be described in the subsequent specification, and, in part, will be obvious from the specification, or will be understood by implementing the present invention. The objectives and other advantages of the present invention can be achieved and obtained by the structures specifically pointed out in the specification, the claims, and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings are used to provide a further understanding of the technical solutions of the present invention, and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the technical solutions of the present invention, and do not constitute a limitation to the technical solutions of the present invention.

[0023] The present invention will be further described below in conjunction with the drawings and embodiments; Figure 1 is the circuit schematic diagram of the air conditioner boost circuit provided by Embodiment 1 of the present invention; Figure 2 is the circuit schematic diagram of the air conditioner boost circuit provided by Embodiment 2 of the present invention; Figure 3 is the circuit schematic diagram of the air conditioner boost circuit provided by Embodiment 3 of the present invention; Figure 4 is the control timing diagram of the air conditioner boost circuit provided by the embodiment of the present invention; Figure 5 is the schematic diagram of the zero voltage detection circuit of the air conditioner boost circuit provided by Embodiment 4 of the present invention; Figure 6 is the schematic diagram of the zero voltage detection circuit of the air conditioner boost circuit provided by Embodiment 5 of the present invention; Figure 7 is the schematic diagram of the current sampling circuit and zero current detection circuit of the air conditioner boost circuit provided by Embodiment 6 of the present invention; Figure 8It is the control flowchart of the air conditioner boost circuit provided by the embodiment of the present invention using hardware control; Figure 9 It is the flowchart of the pure software control method of the air conditioner boost circuit provided by the embodiment of the present invention. Specific Embodiments

[0024] This part will describe in detail the specific embodiments of the present invention. The preferred embodiments of the present invention are shown in the drawings. The function of the drawings is to supplement the description of the text part of the specification, enabling people to intuitively and vividly understand each technical feature and the overall technical solution of the present invention, but it cannot be understood as a limitation of the protection scope of the present invention.

[0025] In the description of the embodiments of the present invention, the meaning of several is one or more, the meaning of multiple is more than two, greater than, less than, exceeding, etc. are understood as not including the present number, above, below, within, etc. are understood as including the present number, "at least one" means one or more, and "at least one of the following" and its similar expressions mean any combination of these items, including any combination of single or plural items. If there is a description of "first", "second", etc., it is only for the purpose of distinguishing technical features and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features or implicitly indicating the sequence relationship of the indicated technical features.

[0026] It should be noted that words such as setting, installing, and connecting in the embodiments of the present invention should be understood in a broad sense. Those skilled in the art can reasonably determine the specific meanings of the above words in the embodiments of the present invention in combination with the specific content of the technical solution. For example, the term "connection" can be a mechanical connection, an electrical connection, or a connection that can communicate with each other; it can be directly connected or indirectly connected through an intermediate medium.

[0027] It should be noted that the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0028] Currently, existing boost circuits all need to design an independent energy storage inductor to achieve voltage boost; in addition, existing PFC control methods basically use a hard turn-off method to turn off the switching tube, and some materials describe using the CRM or DCM mode to achieve ZCS zero-current turn-off. Therefore, the existing boost circuit scheme that uses an independent energy storage inductor to achieve voltage boost in the current extremely fast flower requires a large circuit board area and has a high electronic control cost; using the hard turn-off control method, its control method is simple, but it cannot achieve zero-current and zero-voltage turn-off, and the switching loss of the switching tube is large, making it difficult to achieve high-efficiency PFC; in addition, the control method using the CRM or DCM mode can only achieve zero-current turn-off and cannot achieve zero-voltage and zero-current turn-off at the same time, and there is still a certain turn-off loss.

[0029] Based on this, the embodiments of the present invention provide an air conditioner boost circuit, a circuit board and an air conditioner, which can achieve not using a boost inductor and realizing soft-switching control with zero turn-on loss, thereby improving the efficiency of the air conditioner boost circuit.

[0030] The following further elaborates on the embodiments of the present invention in conjunction with the accompanying drawings.

[0031] Figure 1 is the circuit schematic diagram of the air conditioner boost circuit provided by the first embodiment of the present invention; Figure 2 is the circuit schematic diagram of the air conditioner boost circuit provided by the second embodiment of the present invention. Refer to Figure 1 or Figure 2 , the first aspect embodiments of the present invention provide an air conditioner boost circuit, including a common-mode inductor L1, a rectification module 100, a charge and discharge module 200, and a control module 300.

[0032] The common-mode inductor L1, the rectification module 100, and the charge and 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 AC power supply; the AC power supply includes a live wire input terminal Lin and a neutral wire input terminal Nin, the first end of the common-mode inductor L1 is connected to the live wire input terminal Lin of the AC power supply, and the second end of the common-mode inductor L1 is connected to the neutral wire input terminal Nin of the AC power supply.

[0033] Refer to Figure 1 and Figure 2 , the air conditioner boost circuit may further include a first absorption inductor CX1, and both 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 together constitute the EMC module of the air conditioner boost circuit, which is used to reduce the electromagnetic radiation of the air conditioner boost circuit.

[0034] The input end of the rectification module 100 is connected to the third end and the fourth end of the common-mode inductor L1.

[0035] The charge and discharge module 200 includes a first switching tube Q1, a first diode D1, and a first capacitor C1. The positive pole of the output end of the rectification module 100 is connected to one switching pin of the first switching 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 pole of the output end of the rectification module 100 is connected to the other switching pin of the first switching tube Q1 and the other end of the first capacitor C1.

[0036] One output terminal of the control module 300 is connected to the control pin of the first switching transistor Q1. The control module 300 is configured to output a PWM signal to the control pin of the first switching transistor Q1 to control the conduction and cutoff of the first switching transistor Q1, determine the duty cycle of the PWM signal according to the input voltage of the AC power supply and the target output voltage, and control the cutoff duration of the first switching transistor Q1 according to the inductor current of the common mode inductor L1.

[0037] According to the air conditioner boost circuit provided by the embodiment of the present invention, by using the leakage inductance in the common mode inductor L1 as the energy storage inductor in the boost circuit to realize the normal operation of the circuit boost, it is possible to achieve without using a boost inductor, saving devices, reducing resource usage, and thus reducing the circuit cost; after the first switching transistor Q1 in the charge and discharge module 200 is turned on, the common mode inductor L1 stores energy; after the first switching transistor Q1 is turned off, the inductor current of the common mode inductor L1 continues to flow through the first diode D1, providing 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 will be loaded across the common mode inductor L1, realizing the reverse flow of the inductor 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 AC power supply, the common mode inductor L1 realizes the release of the junction capacitance charge through the freewheeling effect, and it is possible to achieve zero voltage and zero current turn-on of the first switching transistor Q1. Therefore, by controlling the cutoff duration of the first switching transistor Q1 according to the inductor current of the common mode inductor L1, soft switching control with zero turn-on loss can be achieved, realizing the improvement of the efficiency of the air conditioner boost circuit.

[0038] In the air conditioner boost circuit provided by some embodiments of the present invention, the rectification module 100 may adopt a rectifier bridge device BR1, for example, as shown in Figure 1 shown.

[0039] In the air conditioner boost circuit provided by some other embodiments of the present invention, the rectification module 100 may also be composed of four diodes. For example, as shown in Figure 2 shown, the rectification module 100 includes a second diode D2, a third diode D3, a fourth diode D4, and a fifth diode D5. The third terminal 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 terminal 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 cathodes of the second diode D2 and the third diode D3 are connected together as the positive output terminal of the rectification module 100 and are connected to one switching pin of the first switching transistor Q1 and the anode of the first diode D1. The anodes of the fourth diode D4 and the fifth diode D5 are connected together as the negative output terminal of the rectification module 100 and are connected to the other switching pin of the first switching transistor Q1.

[0040] In the air conditioner boost circuit provided by some embodiments of the present invention, the common mode inductor L1 includes a magnetic core and coils wound around the magnetic core. Among them, the magnetic core can be a ring-shaped magnetic core or a rectangular magnetic core. In addition, the common mode inductor L1 also includes an insulating shell wrapping the magnetic core or an insulating material wound between the magnetic core and the coils to increase the distance between the magnetic core and the coils. It can be understood that different distances between the magnetic core and the coils can cause the common mode inductor L1 to generate different leakage inductances. For the common mode inductor L1 with a rectangular magnetic core, since the wires of the coils are only wound around the magnetic posts on both sides of the magnetic core, and the magnetic path between the magnetic posts on both sides of the magnetic core is relatively long, a relatively large leakage inductance can be generated. Therefore, by controlling the coupling coefficient of the coils on both sides, the leakage inductance of the common mode inductor L1 can be controlled.

[0041] The leakage inductance in the common mode inductor L1 generates self-coupling because most of the magnetic field passes through the air. Therefore, when the air conditioner boost circuit operates, the common mode inductor L1 will cause great interference to the circuit. To solve this problem, in the air conditioner boost circuit provided by some embodiments of the present invention, the outside of the common mode inductor L1 is coated with magnetic powder or magnetic conductive material to achieve the guidance or shielding of the leakage inductance magnetic field of the common mode inductor L1, thereby solving the problem that the common mode inductor L1 will cause great interference to the circuit. Similarly, the common mode inductor L1 can also achieve this purpose by using methods such as adding a shielding case or shielding sponge. 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 will cause great interference to the circuit.

[0042] For Figure 1 and Figure 2 the air conditioner boost circuit in, CCM, CRM, and DCM modes can be used for control, but these control methods do not have the reliability for long-term operation or can only operate with low efficiency. The embodiments of the present invention provide a soft-switching control method. In the air conditioner boost circuit provided by the embodiments in Figure 1 the reverse recovery time of the diode chips in the rectifier bridge device BR1 is greater than 1 μS, and the junction capacitance is greater than 100 pF; in the air conditioner boost circuit provided by the embodiments in Figure 2 the reverse recovery time of the four diodes such as the second diode D2, the third diode D3, the fourth diode D4, and the fifth diode D5 is greater than 1 μS, and the junction capacitance is greater than 100 pF. 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 first switching transistor Q1 is turned off. After the energy of the common mode inductor L1 is released, across the diode junction capacitance of the rectifier module 100 (such as Figure 2, when the live wire input terminal Lin is positive and the neutral wire 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 inductor energy is released, the voltage UD across the diode junction capacitance of the rectification module 100 will be applied across the common mode inductor L1, causing the inductor current of the common mode inductor L1 to flow in the reverse direction. When the voltage across the junction capacitance is equal to the input voltage, the common mode inductor L1 releases the charge of the diode junction capacitance of the rectification module 100 through the freewheeling effect, thereby achieving zero voltage and zero current turn-on of the first switching transistor Q1, and thus achieving soft switching control with zero turn-on loss. Specifically, referring to Figure 4 as shown, Figure 4 The curve corresponding to Q1 on the vertical axis in Figure 4 represents the PWM signal output to the control pin of the first switching transistor Q1, and can also represent the on / off state of the first switching transistor Q1; Figure 4 The curve corresponding to I1 on the vertical axis in represents the inductor current signal of the common mode inductor L1; The curve corresponding to "Vds of Q1" on the vertical axis in represents the voltage signal between the two switching pins of the first switching transistor Q1; At time t1, the first switching transistor Q1 conducts, and the common mode inductor L1 stores energy; the control module 300 calculates the duty cycle of the output PWM signal based on the input voltage of the AC power supply and the output target voltage The duty cycle of the PWM signal is calculated by the formula ; thus controlling the conduction time of the first switching transistor Q1; it should be noted that this 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 this difference by the output target voltage to obtain the duty cycle of the PWM signal. Using this duty cycle to control the conduction time of the first switching transistor Q1 can make the output voltage of the air conditioner boost circuit close to or equal to the output target voltage; , where Cds is the sum of the capacitance of the parasitic capacitance between the two switching pins of the first switching transistor Q1 and the junction capacitance of the two diodes in the rectification 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 for the duration Td is based on Figure 1 The circuit operating principle of the air conditioner boost circuit shown and is obtained by analyzing various measured parameters of the circuit.

[0043] At time t4, the inductor current I1 of the common-mode inductor L1 completes the extraction of the charge of the capacitance of the parasitic capacitance between the two switching pins of the first switching transistor Q1 (such as between the drain and source of the first switching transistor Q1 when Q1 is a MOS transistor) plus the junction capacitance of the two rectifier diodes, i.e., the junction capacitance of the fourth diode D4 + the junction capacitance of the third diode D3, that is, discharges the voltage across the first switching transistor Q1.

[0044] In the air conditioner boost circuit provided by some embodiments of the present invention, the diode chips in 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 fast-recovery diodes, whose reverse recovery time is less than 1 μS, and the diode junction capacitance is less than 100 pF. Accordingly, referring to Figure 3 , the charge and discharge module 200 further includes a second capacitor C2. The two ends of the second capacitor C2 are respectively connected to the positive output terminal and the negative output terminal of the rectification module 100, that is, the second capacitor C2 is connected in parallel between the two switching pins of the first switching transistor Q1 to achieve the soft-switching control function of the air conditioner boost circuit.

[0045] It can be understood that referring to Figure 4 , in the air conditioner boost circuit provided by some embodiments of the present invention, the turn-off duration of the first switching transistor Q1 is equal to the sum of the first duration and the second duration; where: the first duration is the duration from the turn-off of the first switching transistor Q1 until the inductor current of the common-mode inductor L1 drops to zero, that is, Figure 4 The duration between time t2 and time t3 in; the second duration is the duration from when the inductor current flows reversely until it returns to zero, that is, Figure 4 The duration between time t3 and time t4 in.

[0046] Continuing to refer to Figure 4 , in the air conditioner boost circuit provided by some embodiments of the present invention, when the first switching transistor Q1 is turned off and the inductor current I1 of the common-mode inductor L1 drops to zero, or when the inductor current I1 of the common-mode inductor L1 starts to flow reversely, the voltage between the two switching pins of the first switching transistor Q1 starts to drop; when the inductor current I1 of the common-mode inductor L1 flows reversely and returns to zero, the voltage between the two switching pins of the first switching transistor Q1 drops to zero.

[0047] It should be noted that the soft-switching control method of the air conditioner boost circuit in the embodiments of the present invention can be implemented either by hardware control or by software control.

[0048] When implementing the soft-switching control method by hardware control, the control module 300 needs to detect whether the inductor current I1 of the common-mode inductor L1 is zero, or detect whether the voltage between the two switching pins of the first switching transistor Q1 is zero. Specifically, the air conditioner boost circuit can adopt Figure 5 or Figure 6 the zero-voltage detection circuit shown in the figure to detect the voltage between the two switching pins of the first switching transistor Q1, or it can adopt Figure 7 the current sampling circuit and the zero-current detection circuit shown in the figure to detect whether the inductor current I1 of the common-mode inductor L1 is zero.

[0049] Specifically, Figure 5 the air conditioner boost circuit shown in the figure further includes a first resistor R1, a second resistor R2, a sixth diode D6, a seventh diode D7, and a first sampling resistor Rs1. The first sampling resistor Rs1 is connected between the negative output terminal of the rectification module 100 and the switching pin of the first switching transistor Q1. One end of the first resistor R1 is connected to the anode of the first diode D1. The other end of the first resistor R1, one end of the second resistor R2, the anode of the sixth diode D6, and the cathode of the seventh diode D7 are connected together and connected to the input port of the control module 300, so as to output the voltage signal between the two switching pins of the first switching transistor Q1 to the control module 300; the cathode of the sixth diode D6 is connected to the +5V DC power supply terminal; the other end of the second resistor R2 and the anode of the seventh diode D7 are connected to the connection point between the first sampling resistor Rs1 and the first switching transistor Q1.

[0050] In addition, Figure 6 the air conditioner boost circuit shown in the figure further includes 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 terminal of the rectification module 100 and the switching pin of the first switching transistor 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 terminal 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 between the second sampling resistor Rs2 and the first switching transistor Q1; the inverting input terminal of the first comparator ICA1 is connected to the reference voltage REF, and the output terminal of the first comparator ICA1 is connected to the input port of the control module 300, so as to output a level change signal to the control module 300.

[0051] In addition, Figure 7 the shown air conditioner boost circuit further includes 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 terminal of the rectification module 100 and the switching pin of the first switching transistor Q1. The negative output terminal of the rectification module 100 is also connected to the inverting input terminal of the second comparator ICA2 through the fifth resistor R5. The connection point between the third sampling resistor Rs3 and the first switching transistor Q1 is connected to the non-inverting input terminal of the second comparator ICA2 through the sixth resistor R6. Both ends of the seventh resistor R7 are respectively connected to the inverting input terminal and the output terminal of the second comparator ICA2. The output terminal of the second comparator ICA2 is also connected to the non-inverting input terminal of the third comparator ICA3 and the input port of the control module 300. The inverting input terminal of the third comparator ICA3 is connected to the reference voltage REF. The output terminal of the third comparator ICA3 is also connected to the input port of the control module 300, so as to implement an output level change signal to be given to the control module 300.

[0052] In the air conditioner boost circuit provided by some embodiments of the present invention, referring to Figure 8 , the process of implementing soft-switching control through hardware control is as follows: The control module 300 first controls the first switching transistor Q1 to conduct; The control module 300 then controls the first switching transistor Q1 to turn off; After the first switching transistor Q1 turns off, when it is detected that the inductor current reverses and returns to zero or it is detected that the voltage between the two switching pins of the first switching transistor Q1 drops to zero, the control module 300 controls the first switching transistor Q1 to conduct.

[0053] In this embodiment, when Figure 7 the shown current sampling circuit and zero-current detection circuit are adopted, the comparator is used to judge the inductor current. When the inductor current is lower than 0 A (or close to 0 A, such as below 2 A), the comparator device outputs a flipped output level change signal to notify the control module 300. The control module 300 can use edge triggering to enter the interrupt processing, so as to achieve high-efficiency and high-reliability zero-current detection of the control module 300; similarly, when Figure 5 or Figure 6 the shown zero-voltage detection circuit is adopted, when it is detected that the voltage between the two switching pins of the first switching transistor Q1 is zero, edge triggering is achieved through the control module 300.

[0054] In the air conditioner boost circuit provided by some embodiments of the present invention, referring to Figure 9 , the process of implementing soft-switching control through a pure software control method is as follows: The control module 300 first controls the first switching transistor Q1 to conduct; When the inductance sampling current I1 of the common-mode inductor L1 at the midpoint is turned on, record the time difference between the sampling time of the inductance sampling current I1 of the common-mode inductor L1 and the turn-on time of the first switching transistor Q1 as ; According to the input voltage of the AC power supply , the inductance sampling current I1 of the common-mode inductor L1 collected, and the time difference between the sampling time of the inductance sampling current I1 of the common-mode inductor L1 and the turn-on time of the first switching transistor Q1 calculate the inductance L1 of the common-mode inductor L1, and the calculation formula is: ; It should be noted that the calculation formula for the inductance L1 of the common-mode inductor L1 is based on Figure 1 the circuit operating principle of the air conditioner boost circuit shown and based on the analysis of various measured parameters of the circuit.

[0055] Calculate the duration when the inductance current of the common-mode inductor L1 drops to zero after the first switching transistor Q1 is turned off, denoted as the first duration T1, and the calculation formula is: ; and calculate the duration when the inductance current of the common-mode inductor L1 returns to zero after flowing in the reverse direction, which is the second duration Td, and the calculation formula is: ; Cds is the sum of the capacitance of the parasitic capacitance between the two switching pins of the first switching transistor Q1 and the junction capacitance of the two diodes in the rectification module 100; and calculate the turn-off duration of the first switching transistor Q1, which is the third duration T3, and the calculation formula is: T3 = T1 + Td; It should be noted that the calculation formulas for the first duration T1 and the second duration Td are based on Figure 1 the circuit operating principle of the air conditioner boost circuit shown and based on the analysis of various measured parameters of the circuit; The control module 300 controls the first switching transistor Q1 to turn off; After the turn-off duration of the first switching transistor Q1 reaches the third duration T3, the control module 300 controls the first switching transistor Q1 to turn on again.

[0056] In this embodiment, by using the leakage inductance in the common-mode inductor L1 as the energy storage inductor in the boost circuit to achieve the normal operation of the circuit boost, it is possible to achieve the boost without using a boost inductor, saving components and reducing resource usage, thereby reducing the circuit cost. After the first switch Q1 in the charge and discharge module 200 is turned on, the common-mode inductor L1 stores energy. After the first switch Q1 is turned off, the inductor current of the common-mode inductor L1 continues to flow through the first diode D1, providing a low-impedance loop for the energy released by the common-mode inductor L1. After the energy release of the common-mode inductor L1 is completed, the junction capacitance voltage of the rectification module 100 will be applied across the two ends of the common-mode inductor L1, causing the inductor current of the common-mode inductor L1 to flow in the reverse direction. When the junction capacitance voltage of the rectification module 100 is equal to the voltage of the input AC power supply, the common-mode inductor L1 realizes the release of the junction capacitance charge through the freewheeling effect, enabling the zero-voltage and zero-current turn-on of the first switch Q1. Therefore, by controlling the off-duration of the first switch Q1 according to the inductor current of the common-mode inductor L1, soft-switching control with zero turn-on loss can be achieved, improving the efficiency of the air conditioner boost circuit.

[0057] In addition, an embodiment of the second aspect of the present invention provides a circuit board including the air conditioner boost circuit as in the first aspect embodiment above.

[0058] In addition, an embodiment of the third aspect of the present invention provides an air conditioner including the air conditioner boost circuit as in the first aspect embodiment above, or including the circuit board as in the second aspect embodiment above.

[0059] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made without departing from the spirit of the present invention within the knowledge scope of those of ordinary skill in the art.

Claims

1. An air conditioner boost circuit, characterized in that It includes a control module, a common-mode inductor, a rectification module, and a charge and discharge module connected in sequence; The charge and discharge module includes a first switch tube connected to the output end of the rectification module, a first diode connected to the first switch tube, and a first capacitor connected to the first diode; The control module is connected to 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 of the AC power supply connected to the common-mode inductor and the output target voltage, and control the off duration of the first switch tube according to the inductor current of the common-mode inductor.

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

3. The air conditioner boost circuit according to claim 2, wherein 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.

4. The air conditioner boost circuit according to claim 2, wherein, 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. The charge and discharge module further includes a second capacitor, and both ends of the second capacitor are respectively connected to the positive output terminal and the negative output terminal of the rectification module.

5. The air conditioner boost circuit according to claim 1, wherein The duty cycle of the PWM signal is calculated using the following formula: Where: D is the duty cycle, is the output target voltage, is the input voltage of the AC power supply.

6. The air conditioner boost circuit according to claim 1, wherein The off duration of the first switch tube is equal to the sum of a first duration and a second duration; where: the first duration is the duration when the inductor current of the common-mode inductor drops to zero after the first switch tube is turned off; the second duration is the duration when the inductor current returns to zero after flowing reversely.

7. The air conditioner boost circuit according to claim 6, characterized in that, When the first switch tube is turned off and the inductor current of the common-mode inductor drops to zero, or when the inductor current starts to flow reversely, the voltage between the two switch pins of the first switch tube starts to drop; when the inductor current flows reversely and returns to zero, the voltage between the two switch pins of the first switch tube drops to zero.

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

9. The air conditioner boost circuit according to claim 6, characterized in that, The first duration is calculated using the following formula: ； Wherein: T1 is the first duration, L1 is the inductance of the common-mode inductor, and 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 using the following formula: ； The time difference between the sampling time of the inductance sampling current of the common-mode inductor and the turn-on time of the first switching transistor.

10. The air conditioner boost circuit according to claim 9, characterized in that, The second duration is calculated using the following formula: Where: Cds is the sum of the capacitance of the parasitic capacitance between the two switch pins of the first switch tube and the junction capacitance of the two diodes in the rectification module.

11. The air conditioner boost circuit according to claim 10, characterized in that, After the first switch tube is turned off, when it is detected that the off duration of the first switch tube reaches the sum of the first duration and the second duration, the control module controls the first switch tube to conduct.

12. The air conditioner boost circuit according to claim 1, wherein The common-mode inductor includes a magnetic core and a coil wound around the magnetic core; the common-mode inductor further includes an insulating shell wrapping the magnetic core or an insulating material wound between the magnetic core and the coil to increase the distance between the magnetic core and the coil.

13. The air conditioner boost circuit according to claim 1, characterized in that, The outside of the common-mode inductor is coated with magnetic powder or a magnetic conductive material.

14. The air conditioner boost circuit according to claim 1, wherein, The air conditioner boost circuit further includes a first absorption inductor, and both ends of the first absorption inductor are respectively connected to the first end and the second end of the common-mode inductor.

15. A circuit board, characterized in that, It includes the air conditioner boost circuit described in any one of claims 1 to 14.

16. An air conditioner, characterized in that, It includes the air conditioner boost circuit described in any one of claims 1 to 14, or includes the circuit board described in claim 15.

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