Resistance removal control circuit and air conditioner

Abstract

The utility model discloses a resistance cut-off control circuit and an air conditioner, the resistance cut-off control circuit comprises a voltage detection circuit, the input end of the voltage detection circuit is used for accessing the output end of a power supply module, and the voltage detection circuit is used for detecting the bus voltage output by the power supply module and outputting a corresponding voltage detection signal; the input end of the first switching circuit is connected with a first power supply, and the output end of the first switching circuit is connected with the controlled end of the relay; the trigger circuit is electrically connected with the output end of the voltage detection circuit and the controlled end of the first switching circuit, and the trigger circuit is further used for being connected with reference voltage and being triggered when the voltage of the voltage detection signal reaches the reference voltage, controlling the first switching circuit to be switched on and driving the relay to bypass the thermistor; the technical scheme of the utility model aims to reduce the dependence of a thermistor cutting scheme on internal resources of a processor.

Description

TECHNICAL FIELD

[0001] The utility model relates to air conditioner technical field especially relates to a resistance cut-off control circuit and air conditioner. BACKGROUND

[0002] At present, after the power module is powered on for a period of time (after the bus capacitor tends to be stable), it needs to short-circuit the thermistor connected in series at the input end of the relay (that is, cut off the thermistor). However, in the existing thermistor cut-off control process, since it relies on the processor for timing and analog sampling, the corresponding control scheme needs to divide the control system into strong and weak electrical zones during design, thereby occupying a large safety distance. UTILITY MODEL CONTENTS

[0003] The main purpose of the utility model is to provide a resistance cut-off control circuit and air conditioner, which aims to reduce the dependence of the thermistor cut-off scheme on the internal resources of the processor.

[0004] To achieve the above purpose, the resistance cut-off control circuit provided by the utility model, the air conditioner includes a power module, a thermistor and a relay, the thermistor is electrically connected with the input end of the power module, the relay is connected in parallel across the thermistor, and the resistance cut-off control circuit comprises:

[0005] A voltage detection circuit, the input end of which is used to access the output end of the power module, the voltage detection circuit is used to detect the bus voltage output by the power module and output the corresponding voltage detection signal;

[0006] A first switch circuit, the input end of which is used to access a first power supply, and the output end of which is used to access the controlled end of the relay;

[0007] A trigger circuit, which is electrically connected with the output end of the voltage detection circuit and the controlled end of the first switch circuit respectively, the trigger circuit is also used to access a reference voltage, and

[0008] The trigger circuit is triggered when the voltage of the voltage detection signal reaches the reference voltage, controls the first switch circuit to be conductive, and drives the relay to bypass the thermistor.

[0009] In some embodiments, the trigger circuit comprises:

[0010] A flip-flop, including a ground pin, a trigger pin, an output pin, a reset pin, a threshold pin, a detection pin and a power pin, the ground pin is grounded, the trigger pin and the detection pin are connected with the output end of the voltage detection circuit respectively, the output pin is connected with the controlled end of the first switch circuit, the threshold pin accesses the reference voltage, and the power pin is used to access the first power supply;

[0011] a first resistor, a first end of the first resistor being connected to the first power supply, a second end of the first resistor being connected to the reset pin;

[0012] a first capacitor and a second capacitor, the first capacitor and the second capacitor being connected in series between the power supply pin and the ground;

[0013] a third capacitor, the third capacitor being connected in series between the threshold pin and the ground.

[0014] In some embodiments, the first switch circuit comprises:

[0015] a first switch tube, an input end of the first switch tube being the input end of the first switch circuit, an output end of the first switch tube being the output end of the first switch circuit;

[0016] a second resistor, the second resistor being connected in parallel between the input end of the first switch tube and a control end of the first switch tube;

[0017] a third resistor, a first end of the third resistor being connected to the control end of the first switch tube, a second end of the third resistor being the control end of the first switch circuit.

[0018] In some embodiments, the voltage detection circuit comprises:

[0019] a first voltage dividing resistor, a first end of the first voltage dividing resistor being the output end of the voltage detection circuit, a second end of the first voltage dividing resistor being connected to the ground;

[0020] a second voltage dividing resistor, a first end of the second voltage dividing resistor being the input end of the voltage detection circuit, a second end of the second voltage dividing resistor being connected to the second end of the first voltage dividing resistor;

[0021] a first zener diode, the first zener diode being connected in parallel between the two ends of the first voltage dividing resistor.

[0022] In some embodiments, the resistance removal control circuit further comprises:

[0023] a voltage stabilizing circuit, an input end of the voltage stabilizing circuit being connected to the output end of the power module, an output end of the voltage stabilizing circuit being connected to the trigger circuit and the input end of the first switch circuit, the voltage stabilizing circuit being configured to stabilize the bus voltage connected thereto and output a corresponding first power supply.

[0024] In some embodiments, the voltage stabilizing circuit comprises:

[0025] a second switch tube, an input end of the second switch tube being the input end of the voltage stabilizing circuit, an output end of the second switch tube being the output end of the voltage stabilizing circuit;

[0026] a second zener diode, a cathode of the second zener diode being connected to a control end of the second switch tube, an anode of the second zener diode being connected to the ground;

[0027] a fourth resistor and a fifth resistor, the fourth resistor and the fifth resistor being connected in series between the input end of the second switch tube and the control end of the second switch tube;

[0028] A fourth capacitor is connected in series between the output terminal of the second switch tube and the ground.

[0029] In some embodiments, the resistance removal control circuit further comprises:

[0030] A reference voltage generation circuit is connected in series between the output terminal of the voltage stabilizing circuit and the trigger circuit, and the reference voltage generation circuit is configured to perform voltage conversion on the accessed first power supply and output a corresponding reference voltage to the trigger circuit.

[0031] In some embodiments, the resistance removal control circuit further comprises:

[0032] A freewheeling circuit is connected in parallel across the coil of the relay, and the freewheeling circuit is configured to freewheel the coil of the relay when the trigger circuit is triggered.

[0033] The utility model also provides a kind of air conditioner, and the air conditioner includes power module, thermistor and above-mentioned resistance removal control circuit;

[0034] The first input terminal of the power module is used to access live wire, the second input terminal of the power module is connected to zero line through thermistor, and the input terminal of the power module is connected with the collection terminal of the resistance removal control circuit.

[0035] In some embodiments, the air conditioner further comprises a first load and a second load connected with the output terminal of the power module respectively.

[0036] The resistance removal control circuit is further configured to connect the second load with the output terminal of the power module after bypassing the thermistor according to the detected bus voltage.

[0037] Wherein, the operating power of the first load is lower than the operating power of the second load.

[0038] The utility model technical scheme combines trigger circuit and voltage detection circuit, uses pure hardware scheme to monitor bus voltage in real time, controls relay through first switch circuit, all control circuits are completed in strong electric side, and the removal control process of thermistor does not need processor to participate, perfectly solves the problem that ordinary thermistor removal scheme depends on internal resource of processor, and leads to the problem that control system occupies large safety distance due to strong and weak electric area. BRIEF DESCRIPTION OF DRAWINGS

[0039] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced as follows. Obviously, the drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained according to the structures shown in these drawings without creative labor.

[0040] Figure 1 The structural schematic diagram of an embodiment of the resistance removal control circuit of the present application;

[0041] Figure 2 The structural schematic diagram of another embodiment of the resistance removal control circuit of the present application;

[0042] Figure 3 The structural schematic diagram of still another embodiment of the resistance removal control circuit of the present application;

[0043] Figure 4 The circuit connection diagram of an embodiment of the trigger circuit in the present application;

[0044] Figure 5 The circuit connection diagram of an embodiment of the first switch circuit in the present application;

[0045] Figure 6 The circuit connection diagram of an embodiment of the voltage detection circuit in the present application;

[0046] Figure 7 The circuit connection diagram of an embodiment of the voltage detection circuit in the present application;

[0047] Figure 8 The structural schematic diagram of an embodiment of the air conditioner of the present application;

[0048] Figure 9 The voltage waveform diagram of an embodiment of the present application in simulation;

[0049] Figure 10 The voltage waveform diagram of another embodiment of the present application in simulation;

[0050] Figure 11 The voltage waveform diagram of still another embodiment of the present application in simulation;

[0051] Figure 12 The voltage waveform diagram of an embodiment of the present application when the existing power module is powered on;

[0052] Figure 13 The voltage waveform diagram of another embodiment of the present application when the existing power module is powered on.

[0053] Explanation of drawing reference numerals:

[0054]

[0055] The purposes, functional features and advantages of the utility model will be further described in combination with embodiments with reference to the drawings. DETAILED DESCRIPTION

[0056] The technical solutions in the embodiments of the utility model will be clearly and completely described below in combination with the drawings in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the utility model.

[0057] In addition, the description such as "first", "second" and the like in the utility model is only for the purpose of description, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" can explicitly or implicitly include at least one feature. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the realization of those skilled in the art, when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, and is not within the protection scope required by the utility model.

[0058] The utility model provides a kind of resistance cut-off control circuit.

[0059] Reference Figure 1 In an embodiment, the resistance cut-off control circuit is applied to an air conditioner, the air conditioner includes a power module, a thermistor and a relay, the thermistor is electrically connected with the input end of the power module, the relay is connected in parallel across the thermistor, and the resistance cut-off control circuit includes:

[0060] A voltage detection circuit 10, an input end of which is used to access the output end of the power module, and the voltage detection circuit 10 is used to detect the bus voltage output by the power module and output a corresponding voltage detection signal;

[0061] A first switch circuit 20, an input end of which is used to access a first power supply, and an output end of which is used to access the controlled end of the relay;

[0062] A trigger circuit 30, which is electrically connected with the output end of the voltage detection circuit 10 and the controlled end of the first switch circuit 20 respectively, and the trigger circuit 30 is also used to access a reference voltage, and

[0063] The first switch circuit 20 is controlled to be turned on when the voltage value of the voltage detection signal reaches the voltage value of the reference voltage, and the relay is driven to bypass the thermistor.

[0064] It should be noted that in the power module, a high-voltage large-capacity energy storage capacitor charging circuit is arranged, and since the charging current of the bus capacitor in the initial state is mainly determined by the equivalent series resistance thereof, Figure 12 is the simulation of the power-on impact of the diode in the uncontrolled bridge rectifier circuit without any measures. It can be found from the simulation data that the impact current at the power-on moment is very high, which can reach 455A. This current directly impacts the strong current input device. Therefore, in the uncontrolled bridge rectifier circuit, a thermistor and a relay are usually used to limit the impact current at the power-on moment, so as to reduce the influence of the large current at the power-on moment on the capacitor, the rectifier bridge stack and other strong current side devices.

[0065] In the embodiment, the trigger circuit 30 includes a flip-flop U1 and an external peripheral circuit thereof. The voltage detection signal connected to the trigger circuit 30 is used to represent the size of the bus voltage, and the voltage value thereof is positively correlated with the voltage value of the bus voltage. The reference voltage is used to represent the threshold voltage value for cutting off the thermistor. Therefore, by connecting the voltage detection signal and the reference voltage to the trigger circuit 30 at the same time, the trigger circuit 30 can be triggered when the bus voltage is lower than the threshold voltage value for cutting off the thermistor, so as to control the relay. It is not necessary to rely on the processor for analog-to-digital conversion or delay closing.

[0066] Specifically, the contact of the relay is a normally open contact. After the air conditioner is powered on, the alternating current in the power grid is input to the power module. At this time, since the contact is in the off state, the thermistor is connected to the input end of the power module, so as to limit the impact current at the power-on moment and avoid that the large current breaks down the strong current side device.

[0067] After the power module is connected to the alternating current, the power module performs rectification processing on the alternating current, and outputs a corresponding bus voltage to supply power to the rear-end load. At this time, the input end of the voltage detection circuit 10 samples the bus voltage, and outputs a voltage detection signal corresponding to the voltage value to the trigger circuit 30. Since the reference voltage of the trigger circuit 30 represents the threshold voltage value for cutting off the thermistor, when the impact current at the power-on moment is too high, the corresponding voltage is also too high. At this time, the voltage value of the voltage detection signal is greater than the voltage value of the reference voltage, and the trigger condition of the trigger circuit 30 is not reached. Therefore, the trigger circuit 30 does not act, the contact is in the default off state, and the thermistor remains connected.

[0068] For example, in the case of Figure 13 , when a 47Ω thermistor is connected in series on the alternating current side, the impact current connected to the diode in the rectifier circuit is reduced to 3.6A, which better suppresses the influence of the power-on impact current on the device.

[0069] After a period of time after power-on (i.e. after the bus capacitor tends to be stable), the impact current decreases, and the corresponding voltage also decreases, and the voltage value of the voltage detection signal also decreases. When the voltage value of the voltage detection signal is lower than the voltage value of the reference voltage, the trigger condition of the trigger circuit 30 is reached, the trigger circuit 30 is triggered, and the first switch circuit 20 is controlled to connect the loop in which the relay coil is located, and the coil attracts the contact to bypass the thermistor (i.e. cut off the thermistor).

[0070] Thus, the system efficiency is reduced due to the increase of the resistance value of the thermistor with the temperature rise, and the situation that the entire circuit system cannot work normally due to the voltage division of the thermistor on the circuit under the large current operating condition of the rear stage circuit is also reduced.

[0071] The technical scheme of the utility model combines the trigger circuit 30 with the voltage detection circuit 10, uses a pure hardware scheme to monitor the bus voltage in real time, controls the relay through the first switch circuit 20, all control circuits are completed on the strong current side, and the cut-off control process of the thermistor does not need the participation of the processor, which perfectly solves the problem that the ordinary thermistor cut-off scheme relies on the internal resources of the processor and causes the control system to occupy a large safety distance between the strong current and the weak current.

[0072] Reference Figure 1 and Figure 4 In an embodiment, the trigger circuit 30 comprises:

[0073] The trigger U1 comprises a ground pin, a trigger pin, an output pin, a reset pin, a threshold pin, a detection pin and a power pin, the ground pin is grounded, the trigger pin and the detection pin are connected with the output end of the voltage detection circuit 10 respectively, the output pin is connected with the controlled end of the first switch circuit 20, the threshold pin is connected with the reference voltage, and the power pin is connected with the first power supply;

[0074] The first resistor R1 has a first end for connecting with the first power supply and a second end connected with the reset pin;

[0075] The first capacitor C1 and the second capacitor C2 are connected in series between the power pin and the ground respectively;

[0076] The third capacitor C3 is connected in series between the threshold pin and the ground.

[0077] In the embodiment, the first resistor R1 is a voltage dividing resistor, the first capacitor C1 and the second capacitor C2 are used for filtering the connected first power supply, and the third capacitor C3 is an external decoupling capacitor of the reference voltage, which prevents external noise from interfering with the reference voltage.

[0078] Specifically, taking the trigger U1 model NE555 as an example, the trigger pin is connected with the voltage detection signal, and a comparator is connected with the ground pin in the chip, that is, when the positive bus voltage is detected, the trigger U1 is started, at this time, another comparator in the trigger U1 compares the voltage value of the voltage detection signal connected with the detection pin with the voltage value of the reference voltage connected with the threshold pin, when the voltage value of the voltage detection signal is lower than the voltage value of the reference voltage, the trigger U1 is triggered, and the control signal of the corresponding level is output to the first switch circuit 20 through the output pin.

[0079] Referring to Figure 1 and Figure 5 In an embodiment, the first switch circuit 20 comprises:

[0080] The first switch tube Q1, the input end of which is the input end of the first switch circuit 20, and the output end of which is the output end of the first switch circuit 20;

[0081] The second resistor, which is connected in parallel with the input end of the first switch tube Q1 and the controlled end of the first switch tube Q1;

[0082] The third resistor R3, the first end of which is connected with the controlled end of the first switch tube Q1, and the second end of which is the controlled end of the first switch circuit 20.

[0083] In this embodiment, the output end of the first switch circuit 20 is connected with the coil of the relay, so that the first power supply connected forms a current loop with the coil through the first switch circuit 20, thereby controlling the power supply of the coil by controlling the first switch circuit 20, and driving the contact to bypass or stop bypassing the thermistor.

[0084] Specifically, the first switch tube Q1 is a PNP type triode or a PMOS tube, so the level of the control signal is low. At this time, the second resistor acts as a pull-up resistor, which pulls up the controlled end of the first switch tube Q1 to high level when the trigger circuit 30 is not triggered, keeps the first switch tube Q1 in off state, and disconnects the coil from the loop, so as not to attract the contact.

[0085] When the trigger circuit 30 is triggered, a low level is output to the first switch circuit 20, at this time, the controlled end of the first switch tube Q1 is pulled down to the ground through the third resistor R3, and the first switch tube Q1 connects the coil to the loop, controls the coil to attract the contact, and bypasses the thermistor.

[0086] Referring to Figure 1 and Figure 6 In an embodiment, the voltage detection circuit 10 comprises:

[0087] a first voltage detection circuit 10, and a second end connected to a second end of the first voltage dividing resistor Ra;

[0088] a second voltage dividing resistor Rb, a first end of which is an input end of the first voltage detection circuit 10, and a second end of which is connected to the second end of the first voltage dividing resistor Ra;

[0089] a first voltage stabilizing tube DZ1 connected in parallel to both ends of the first voltage dividing resistor Ra.

[0090] In the embodiment, the number of the second voltage dividing resistors Rb can be multiple, and when the number of the second voltage dividing resistors Rb is multiple, the multiple second voltage dividing resistors Rb are connected in series between the first end of the first voltage dividing resistor Ra and the output end of the first voltage detection circuit 10.

[0091] Specifically, taking the second voltage dividing resistor Rb including two resistors Rb1 and Rb2 as an example, Ra, Rb1 and Rb2 are a voltage dividing network, the breakdown voltage of the voltage stabilizing diode DZ1 is 12V, which is used for voltage clamping of the voltage detection signal VBUS_TEST to prevent uncontrollable factors from causing the voltage of the voltage detection signal VBUS_TEST to exceed the supply rail voltage (VCC) of the trigger circuit 30. The voltage dividing value of the first voltage dividing resistor Ra and the reference voltage jointly determine the cut-off time of the thermistor, that is, when the value of VBUS_TEST reaches the voltage value of the reference voltage, the contact is attracted.

[0092] The critical bus voltage for the action of the trigger circuit 30 can be calculated according to the following formula:

[0093] ;

[0094] Note: This formula is a calculation method under ideal state. Among them, According to the actual test result, if the voltage dividing network inside the trigger circuit 30 is used, the theoretical value is . Since the cut-off of the thermistor needs to meet: * > In order to ensure that the contact can be normally attracted, VBUS should be the working condition of the lowest input of the power grid and the contact is disconnected, and the corresponding bus voltage, among them, taking 220V nominal voltage as an example, the working voltage of the lowest input of the circuit = 220*(1-20%) = 176V.

[0095] Referring to Figure 2 , in an embodiment, the resistance cut-off control circuit further comprises:

[0096] A voltage stabilizing circuit 40, an input end of which is connected to an output end of the power module, an output end of which is connected to the trigger circuit 30 and the input end of the first switch circuit 20, is used to stabilize the bus voltage and output the corresponding first power supply.

[0097] In this embodiment, the voltage stabilizing circuit 40 is used to stabilize and step down the bus voltage and output the corresponding first power supply to provide power supply for the entire module circuit.

[0098] Referring to Figure 2 and Figure 7 In an embodiment, the voltage stabilizing circuit 40 comprises:

[0099] A second switch tube Q2, an input end of which is the input end of the voltage stabilizing circuit 40, and an output end of which is the output end of the voltage stabilizing circuit 40;

[0100] A second voltage stabilizing tube DZ2, a cathode of which is connected to the controlled end of the second switch tube Q2, and an anode of which is grounded;

[0101] A fourth resistor R4 and a fifth resistor R5, which are connected in series between the input end of the second switch tube Q2 and the controlled end of the second switch tube Q2;

[0102] A fourth capacitor C4, which is connected in series between the output end of the second switch tube Q2 and the ground.

[0103] In this embodiment, VCC is established in a short time after the power module is powered on. The VCC voltage provides a bias voltage for the second switch tube Q2 through the second voltage stabilizing tube DZ2, the fourth resistor R4 and the fifth resistor R5. The design of this circuit needs to consider the power consumption of the second switch tube Q2, the second voltage stabilizing tube DZ2, the fourth resistor R4 and the fifth resistor R5. Here, the fourth resistor R4 and the fifth resistor R5 are used in series to increase the total withstand voltage.

[0104] The power consumption of this circuit is the largest when the input alternating voltage is the largest. Taking a single-phase 220V alternating voltage input as an example, the design input voltage is calculated as 220V+(1+20%) and the maximum input alternating voltage is 264V.

[0105] Taking R4=R5=10k and the input alternating voltage VAC=264V as an example:

[0106] ;

[0107] The second voltage stabilizing tube DZ2 works in the breakdown region, and the voltage V DZ2 between the two ends is 12V. Assuming that the current flowing through the second voltage stabilizing tube DZ2 is I DZ2 , the power of the second voltage stabilizing tube DZ2 is PDZ2 Then we have:

[0108]

[0109]

[0110] When the second voltage regulator DZ2 selected is 12V / 0.5W, the power consumption margin: =43%, which meets the design requirements.

[0111] Since R5 = R4, and in series with DZ2, we have = = =18ma, only need to evaluate any one of the resistance power:

[0112]

[0113] Note: R4, R5 resistance value can be adjusted according to the load driving demand of VCC, and the design power consumption of the second voltage regulator DZ2, until the design requirements are met.

[0114] Referring to Figure 2 , in an embodiment, the resistance removal control circuit further comprises:

[0115] Reference voltage generating circuit 50 in series between the output of the voltage regulator circuit 40 and the trigger circuit 30, the reference voltage generating circuit 50 for voltage conversion processing of the first power supply connected, output corresponding reference voltage to the trigger circuit 30.

[0116] In this embodiment, the circuit can set the cut-off voltage of the thermistor, that is, when Triggre_Set>VBUS_TEST is detected, the contact is closed and the thermistor is cut off. The voltage value of the reference voltage Triggre_Set can be set by the voltage dividing network inside the trigger circuit 30 (which can be referred to the internal block diagram of NE555 time base circuit), or the voltage parameter of the pin can be set by external resistance voltage dividing or other ways.

[0117] Referring to Figure 3 , in an embodiment, the resistance removal control circuit further comprises:

[0118] Free-wheeling circuit 60 in parallel with both ends of the coil of the relay, the free-wheeling circuit 60 for freewheeling the coil of the relay when the trigger circuit 30 is triggered.

[0119] In this embodiment, the free-wheeling circuit 60 includes a free-wheeling diode, since the relay coil is an inductive load, the free-wheeling diode is used for freewheeling.

[0120] The utility model discloses a kind of air conditioners, the air conditioner includes power module, thermistor and the resistance cut-off control circuit of above-mentioned;

[0121] The first input end of the power module is used for connecting live wire, the second input end of the power module connects zero line through thermistor, and the input end of the power module is connected with the collection end of the resistance cut-off control circuit.

[0122] In the embodiment, the effective value of alternating current is 174V / 50Hz, The voltage dividing network inside trigger circuit 30 is used to provide , which is described as follows:

[0123] Through the analysis of Figure 9 When the alternating current is 174V, the theoretical bus voltage VBUS=1.414*174=246V. The critical cut-off point of thermistor cut-off circuit is designed as , which meets the requirement that the theoretical bus voltage VBUS is greater than the design cut-off thermistor, i.e. 246V>187V. However, from Figure 9 waveform analysis, when VBUS tends to be stable, it is about 160V, which does not reach the theoretical 246V, and the coil of the relay is always in a power-off state. Through the analysis of the voltage across the thermistor, there is a voltage division across the thermistor when current flows through it, which reduces the bus voltage and causes the relay to fail to act. In order to avoid such problems, the trigger value of VBUS can be reduced by appropriately changing the parameter of R18, or the reference voltage (Triggre_Set) can be reduced to achieve the purpose of cutting off the thermistor (closing the contact).

[0124] The critical cut-off point of thermistor cut-off circuit is set to 160V range again, and the first voltage dividing resistor Ra is changed to 1100Ω. When VBUS reaches 140V, the condition for triggering the relay to close is met, and the simulation result is shown in Figure 10 .

[0125] (2) Verification of self-adaptive bus capacitor capacity cut-off thermistor duration (closing the contact of the relay):

[0126] Compared with Figure 10 , the capacity of bus capacitor is reduced from 0.01F to 0.001F, and the specific waveform is shown in Figure 11 , Figure 11 By reducing the capacity of bus capacitor, the time for the relay to close is changed from 2.8s to 0.3s, which meets the constraint of the formula T=RC of capacitor charging time constant, i.e. the larger the capacitor, the longer the charging time.

[0127] Refer to Figure 8In an embodiment, the air conditioner further comprises a first load and a second load respectively connected to the output of the power module;

[0128] The resistance removal control circuit is further configured to connect the second load to the output of the power module after bypassing the thermistor according to the detected bus voltage;

[0129] The first load has a lower operating power than the second load.

[0130] In the embodiment, the resistance removal control circuit further comprises a second switch circuit 70, the first load is a low-power load in the system, and the second load is a high-power load in the system. In the application of the thermistor power-on anti-impact scheme, only when the contact is closed can the high-power load start. Otherwise, the thermistor will be overheated and damaged, or the system cannot operate normally.

[0131] Since the trigger circuit 30 used comprises a reset / set trigger U1, the dead zone voltage (hysteresis comparison feature of the reset / set trigger U1) of the output level action (i.e. control of the on-off of the relay) can be set. Fluctuation of the input voltage or frequent plugging and unplugging of the power supply causes the bus voltage VBUS to fluctuate, which makes the level of the control signal output by the trigger circuit 30 frequently switch, and thus causes adverse consequences.

[0132] The above is only an optional embodiment of the utility model, and does not limit the patent range of the utility model, and any equivalent structural transformation made according to the utility model specification and the drawings, or direct / indirect application in other related technical fields under the utility model concept of the utility model is included in the patent protection range of the utility model.

Claims

1. A resistance cut-off control circuit applied to an air conditioner, the air conditioner comprising a power supply module, a thermistor and a relay, the thermistor being electrically connected to an input end of the power supply module, the relay being connected in parallel to both ends of the thermistor, characterized in that, The resistance removal control circuit comprises: a voltage detection circuit, an input end of which is connected to an output end of a power module, the voltage detection circuit being configured to detect a bus voltage output by the power module and output a corresponding voltage detection signal; a first switch circuit, an input end of which is connected to a first power supply, and an output end of which is connected to a controlled end of the relay; a trigger circuit, which is electrically connected to an output end of the voltage detection circuit and a controlled end of the first switch circuit, and is further configured to be connected to a reference voltage, and the trigger circuit is triggered when the voltage of the voltage detection signal reaches the reference voltage, and controls the first switch circuit to be turned on to drive the relay to bypass the thermistor.

2. The resistance trip control circuit of claim 1, wherein, The trigger circuit comprises: a flip-flop, which comprises a ground pin, a trigger pin, an output pin, a reset pin, a threshold pin, a detection pin, and a power supply pin, the ground pin being connected to ground, the trigger pin and the detection pin being connected to the output end of the voltage detection circuit, the output pin being connected to the controlled end of the first switch circuit, the threshold pin being connected to the reference voltage, and the power supply pin being connected to the first power supply; a first resistor, a first end of which is connected to the first power supply, and a second end of which is connected to the reset pin; a first capacitor and a second capacitor, which are connected in series between the power supply pin and ground; a third capacitor, which is connected in series between the threshold pin and ground.

3. The resistance shunt control circuit of claim 1, wherein, The first switch circuit comprises: a first switch tube, an input end of which is the input end of the first switch circuit, and an output end of which is the output end of the first switch circuit; a second resistor, which is connected in parallel between the input end of the first switch tube and the controlled end of the first switch tube; a third resistor, a first end of which is connected to the controlled end of the first switch tube, and a second end of which is the controlled end of the first switch circuit.

4. The resistance shunt control circuit of claim 1, wherein, The voltage detection circuit comprises: a first voltage dividing resistor, a first end of which is the output end of the voltage detection circuit, and a second end of which is connected to ground; a second voltage dividing resistor, a first end of which is the input end of the voltage detection circuit, and a second end of which is connected to the second end of the first voltage dividing resistor; a first voltage stabilizing tube, which is connected in parallel between the two ends of the first voltage dividing resistor.

5. The resistance shunt control circuit of claim 1, wherein, The resistance removal control circuit further comprises: a voltage stabilizing circuit, an input end of which is connected to the output end of the power module, an output end of which is connected to the trigger circuit and the input end of the first switch circuit, and the voltage stabilizing circuit being configured to output the first power supply after performing voltage stabilizing processing on the input bus voltage.

6. The resistance shunt control circuit of claim 5, wherein, The voltage stabilizing circuit comprises: a second switch tube, an input end of which is the input end of the voltage stabilizing circuit, and an output end of which is the output end of the voltage stabilizing circuit; a second voltage stabilizing tube, a cathode of which is connected to the controlled end of the second switch tube, and an anode of which is connected to ground; a fourth resistor and a fifth resistor, which are connected in series between the input end of the second switch tube and the controlled end of the second switch tube; a fourth capacitor, which is connected in series between the output end of the second switch tube and ground.

7. The resistance shunt control circuit of claim 5, wherein, The resistance removal control circuit further comprises: A reference voltage generating circuit is connected in series between the output terminal of the voltage stabilizing circuit and the trigger circuit, and is configured to convert the voltage of the first power supply to output a corresponding reference voltage to the trigger circuit.

8. The resistance shunt control circuit of claim 1, wherein, The resistance removal control circuit further comprises: A freewheeling circuit is connected in parallel to both ends of the coil of the relay, and is configured to freewheel the coil of the relay when the trigger circuit is triggered.

9. An air conditioner characterized by comprising: The air conditioner comprises a power module, a thermistor, and the resistance removal control circuit according to any one of claims 1-8. A first input terminal of the power module is configured to be connected to a live wire, and a second input terminal of the power module is configured to be connected to a zero wire through the thermistor, and the input terminals of the power module are connected to the collection terminal of the resistance removal control circuit.

10. The air conditioner of claim 9, wherein The air conditioner further comprises a first load and a second load connected to the output terminal of the power module, respectively. The resistance removal control circuit is further configured to connect the second load to the output terminal of the power module after bypassing the thermistor according to the detected bus voltage. The operating power of the first load is lower than the operating power of the second load.

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