An air conditioner

Abstract

The present application relates to an air conditioner, current detection circuit is used for detecting current and outputting overcurrent signal to controller when current exceeds set current value; controller is used for controlling drive chip; drive chip is used for driving compressor; comparator first input end is connected with reference voltage, output end outputs signal to drive chip; diode is used for connecting overcurrent signal output end of current detection circuit and second input end of comparator; overcurrent disappearance delay circuit includes capacitor C2 and resistor R5 connected in series between power supply and ground, and second input end of comparator is connected between capacitor C2 and resistor R5. The present application can collect overcurrent protection signal and send to controller and drive chip, and can also delay fault signal recovery, so that software and hardware can continuously obtain fault signal, and the fault signal obtained by drive chip will not be recovered in a short time. The present application can realize conventional overcurrent signal alarm and delay recovery function, and the circuit is simple, only one comparator, and the price is cheap.

Description

Technical Field

[0001] This invention relates to the field of air conditioner technology, and more specifically, to an air conditioner with a hardware overcurrent protection delay reset circuit. Background Technology

[0002] During operation, the inverter driver for air conditioner compressors may experience problems such as excessive output current or short circuit in the output power supply due to module damage or load short circuit, which threatens the safety of the circuit board.

[0003] When an overcurrent fault occurs in the frequency converter driver, the driver's hardware protection circuit activates, outputting a fault signal. Upon receiving this signal, the driver chip and controller activate their protection mechanisms, cutting off the output signal. At this point, the frequency converter driver current disappears, the hardware overcurrent fault is eliminated, and the circuit returns to normal, ready to restart. However, if the module suffers irreversible damage or a short circuit due to accumulated thermal stress, immediately restoring power will cause the overcurrent fault to recur. Multiple overcurrent faults in a short period can lead to serious damage, potentially destroying the driver board. Therefore, after a hardware overcurrent fault occurs, the output should be locked for a period before resuming normal output to prevent the fault from recurring within a short time.

[0004] Existing frequency converters rely on software protection. This is achieved by adding a delay recovery function to the software after a fault occurs to prevent the fault from recurring in a short period of time. Alternatively, the grid drive circuit can lock the output signal, requiring an enable signal from the software to restart the output.

[0005] To reduce repeated damage caused by recurring faults, effective protection is needed when the fault occurs for the first time, and the secondary output should be delayed. In software, a timer can be used to stop the output for N seconds, but there is also a certain probability of preventing the output from failing, such as: 1. Power failure, the chip loses its fault memory; 2. Interference, the chip resets; 3. The software delay output function fails, etc., all of which will cause damage to the secondary output.

[0006] Some systems use latches to process fault signals and obtain delayed recovery protection signals. However, excessive chip circuitry can easily introduce delays, leading to extended protection time during faults and causing untimely overcurrent fault protection that can damage devices.

[0007] The information disclosed in this background section is only intended to enhance the understanding of the background technology of this application, and therefore may include prior art that is not known to those skilled in the art. Summary of the Invention

[0008] This invention provides an air conditioner that solves the technical problem of poor reliability in existing air conditioners that use software delay reset.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: An air conditioner, comprising: A current detection circuit is used to detect the current and output an overcurrent signal to the controller when the current exceeds a set current value. The controller is configured to output a driver chip control signal when no overcurrent signal is received, and to stop outputting the driver chip control signal when the overcurrent signal is received. A driver chip is used to receive control signals from the driver chip and drive the compressor; The air conditioner also includes: The comparator has its first input terminal connected to a reference voltage and its output terminal outputting a signal to the driver chip. A diode is used to connect the overcurrent signal output terminal of the current detection circuit and the second input terminal of the comparator; The overcurrent disappearance delay circuit includes a capacitor C2 and a resistor R5 connected in series between the power supply and ground, with the second input terminal of the comparator connected between the capacitor C2 and the resistor R5.

[0010] In some embodiments, the capacitor C2 and the resistor R5 form a charging circuit, and the time constant of the capacitor C2 and the resistor R5 is on the order of seconds.

[0011] In some embodiments, the air conditioner includes a resistor R6, the diode is connected to the overcurrent signal output terminal of the current detection circuit, the capacitor C2 and the resistor R6 form a discharge circuit, the time constant of the capacitor C2 and the resistor R6 is on the order of microseconds, and when the resistor R6 is 0, the time constant of the capacitor C2 and the resistor R6 is 0.

[0012] In some embodiments, the air conditioner includes resistors R1 and R2 connected in series. The reference voltage is obtained by voltage division of resistors R1 and R2. One end of the series resistors R1 and R2 is connected to a power supply, and the other end is grounded. The first input terminal of the comparator is connected between resistors R1 and R2, wherein R2 / (R1+R2) is between 60% and 65%.

[0013] In some embodiments, the air conditioner includes a resistor R4 connected between a first input terminal and an output terminal of the comparator, the resistor R4 being used to provide a hysteresis voltage for the comparator.

[0014] In some embodiments, the output of the comparator is connected to a pull-up resistor R3 or a pull-down resistor, wherein the pull-up resistor R3 is connected to a power supply and the pull-down resistor is grounded.

[0015] In some embodiments, the overcurrent signal output terminal of the current detection circuit is connected to a pull-up resistor R8 or a pull-down resistor, wherein the pull-up resistor R8 is connected to the power supply and the pull-down resistor is grounded.

[0016] In some embodiments, the air conditioner includes a charging and discharging circuit consisting of a capacitor C4 and a resistor R7. The overcurrent signal output terminal of the current detection circuit is connected to the charging and discharging circuit consisting of the capacitor C4 and the resistor R7. The resistor R7 is connected in series with the overcurrent signal output terminal of the current detection circuit, and the capacitor C4 is grounded.

[0017] In some embodiments, the time constants of the capacitor C4 and the resistor R7 are on the order of microseconds.

[0018] In some embodiments, the current detection circuit includes: A rectifier circuit is used to convert alternating current into direct current. The first voltage divider circuit includes resistors R9 and R10 connected in series. Resistor R9 is connected to the output of the rectifier circuit, and resistor R10 is grounded. The second voltage divider circuit includes resistors R12 and R11 connected in series, wherein resistor R12 is connected to the power supply and resistor R11 is grounded. The second comparator has its first input terminal connected between resistors R12 and R11, its second input terminal connected between resistors R9 and R10, and its output terminal being the overcurrent signal output terminal of the current detection circuit.

[0019] The technical solution of this invention has the following advantages over the prior art: The air conditioner of this invention includes a current detection circuit, a controller, a driver chip, a diode, a comparator, and an overcurrent disappearance delay circuit. The current detection circuit detects the current and outputs an overcurrent signal to the controller when the current exceeds a set current value. The controller outputs a driver chip control signal when no overcurrent signal is received, and stops outputting the driver chip control signal when an overcurrent signal is received. The driver chip receives the driver chip control signal and drives the compressor. The first input terminal of the comparator is connected to a reference voltage, and its output terminal outputs a signal to the driver chip. The diode connects the overcurrent signal output terminal of the current detection circuit to the second input terminal of the comparator. The overcurrent disappearance delay circuit includes a capacitor C2 and a resistor R5 connected in series between the power supply and ground, with the second input terminal of the comparator connected between capacitor C2 and resistor R5. This invention can both collect overcurrent protection signals and send them to the controller and driver chip, and can also delay fault signal recovery, ensuring that both software and hardware continuously receive fault signals, while the fault signal received by the hardware driver chip will not recover in a short time. This invention can realize conventional overcurrent signal alarm and delayed recovery functions, and the circuit is simple, with only one comparator, and is inexpensive. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the delay reset circuit of an air conditioner according to a specific embodiment of the present invention.

[0022] Figure 2 This is a schematic diagram of an air conditioner according to a specific embodiment of the present invention.

[0023] Figure 3 This is a schematic diagram of the delay reset circuit of an air conditioner according to another specific embodiment of the present invention.

[0024] Figure 4 This is a schematic diagram of an air conditioner according to another specific embodiment of the present invention.

[0025] Figure 5 This is a schematic diagram of the current detection circuit according to a specific embodiment of the present invention.

[0026] Figure 6 This is a circuit diagram of the current detection circuit according to a specific embodiment of the present invention.

[0027] Figure 7 This is a circuit diagram of an air conditioner according to a specific embodiment of the present invention.

[0028] Figure 8 This is a partial pin diagram of an air conditioner controller according to a specific embodiment of the present invention.

[0029] Figure 9 , 10 This is a circuit diagram of the driver chip for the air conditioner section in a specific embodiment of the present invention. Detailed Implementation

[0030] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0031] In the description of this application, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0032] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0033] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0034] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0035] The following disclosure provides many different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0036] In this application, the air conditioner performs a refrigeration cycle by using a compressor, condenser, throttling device, and evaporator. The refrigeration cycle includes a series of processes involving compression, condensation, expansion, and evaporation to cool or heat an indoor space.

[0037] Low-temperature, low-pressure refrigerant enters the compressor, which compresses it into a high-temperature, high-pressure refrigerant gas and discharges the compressed refrigerant gas. The discharged refrigerant gas flows into the condenser. The condenser condenses the compressed refrigerant into a liquid phase, and the heat is released to the surrounding environment through the condensation process.

[0038] The throttling device expands the high-temperature, high-pressure liquid refrigerant that condenses in the condenser into a low-pressure liquid refrigerant. The evaporator evaporates the expanded refrigerant in the throttling device, returning the low-temperature, low-pressure refrigerant gas to the compressor. The evaporator achieves its cooling effect by utilizing the latent heat of refrigerant evaporation to exchange heat with the material being cooled. Throughout the cycle, the air conditioner regulates the temperature of the indoor space.

[0039] The outdoor unit of an air conditioner refers to the part of the refrigeration cycle that includes the compressor and the outdoor heat exchanger. The indoor unit of an air conditioner includes the indoor heat exchanger, and a throttling device can be provided in either the indoor or outdoor unit.

[0040] The indoor and outdoor heat exchangers function as either condensers or evaporators. When the indoor heat exchanger is used as a condenser, the air conditioner functions as a heater in heating mode; when the indoor heat exchanger is used as an evaporator, the air conditioner functions as a cooler in cooling mode.

[0041] The air conditioner of this application can ensure that the controller and drive chip immediately receive the short circuit signal when the short circuit fault occurs, and can also perform delayed recovery after the hardware overcurrent signal disappears, so as to prevent the inverter driver from restarting in a short time, repeatedly triggering the hardware overcurrent protection and damaging the substrate.

[0042] This solution can implement overcurrent protection and perform hardware recovery delay function. After the overcurrent fault disappears, the fault signal is maintained for a period of time to achieve the hardware protection delay function.

[0043] like Figure 2 , 3 As shown, the air conditioner includes a time-delay reset circuit, a controller, and a driver chip.

[0044] In some embodiments, such as Figure 1 As shown, the delay reset circuit includes a current detection circuit, a diode, a comparator, and an overcurrent disappearance delay circuit.

[0045] The current detection circuit is used to detect the current and output an overcurrent signal to the controller when the current exceeds the set current value.

[0046] like Figure 5 , 6 As shown, the current detection circuit includes: A rectifier circuit is used to convert alternating current into direct current.

[0047] The first voltage divider circuit includes resistors R9 and R10 connected in series. Resistor R9 is connected to the output of the rectifier circuit, and resistor R10 is grounded.

[0048] The second voltage divider circuit includes resistors R12 and R11 connected in series. Resistor R12 is connected to the power supply, and resistor R11 is grounded.

[0049] The second comparator has its first input connected between resistors R12 and R11, its second input connected between resistors R9 and R10, and its output is the overcurrent signal output of the current detection circuit.

[0050] The overcurrent signal output terminal of the current detection circuit is connected to either a pull-up resistor R8 or a pull-down resistor. The pull-up resistor R8 is connected to the power supply, and the pull-down resistor is grounded.

[0051] The air conditioner includes a charging and discharging circuit consisting of capacitor C4 and resistor R7. The overcurrent signal output terminal of the current detection circuit is connected to the charging and discharging circuit consisting of capacitor C4 and resistor R7. Resistor R7 is connected in series with the overcurrent signal output terminal of the current detection circuit, and capacitor C4 is grounded.

[0052] The time constants of capacitor C4 and resistor R7 are on the order of microseconds to ensure a fast response when an overcurrent signal is generated.

[0053] The comparator has a first input terminal connected to a reference voltage, a second input terminal connected to a diode D3, and in some embodiments, the second input terminal connected to the input terminal of diode D3. The output terminal outputs a signal to the driver chip.

[0054] Diode D3 is used to connect the overcurrent signal output terminal of the current detection circuit and the second input terminal of the comparator.

[0055] In some embodiments, the output terminal of diode D3 is connected to the overcurrent signal output terminal of the current detection circuit.

[0056] The reference voltage is provided by a voltage divider circuit. The air conditioner includes resistors R1 and R2 connected in series. The reference voltage is obtained by dividing the voltage between resistors R1 and R2. One end of the series resistors R1 and R2 is connected to the power supply, and the other end is grounded. The first input terminal of the comparator is connected between resistors R1 and R2. R2 / (R1+R2) is between 60% and 65%, which is close to the RC constant value. The recovery time of the overcurrent protection signal can be directly calculated using the filter time constant.

[0057] The air conditioner includes a resistor R4, which is connected between the first input and output of the comparator. The resistor R4 is used to provide hysteresis voltage for the comparator.

[0058] The output of the comparator is connected to either a pull-up resistor R3 or a pull-down resistor. The pull-up resistor R3 is connected to the power supply, and the pull-down resistor is grounded.

[0059] The overcurrent disappearance delay circuit includes a capacitor C2 and a resistor R5 connected in series between the power supply and ground, and the second input terminal of the comparator is connected between the capacitor C2 and the resistor R5.

[0060] The charging circuit consists of capacitor C2 and resistor R5, with the time constants of capacitor C2 and resistor R5 being on the order of seconds to provide a delay on the order of seconds.

[0061] The controller is used to output the driver chip control signal when no overcurrent signal is received, and to stop outputting the driver chip control signal when an overcurrent signal is received.

[0062] The driver chip is used to receive control signals from the driver chip and drive the compressor.

[0063] In some embodiments, such as Figure 3 As shown, the delayed reset circuit includes a resistor R6, a diode (in some embodiments, the output terminal of the diode) connected to the overcurrent signal output terminal of the current detection circuit, a capacitor C2 and a resistor R6 forming a discharge circuit, and the time constant of the capacitor C2 and the resistor R6 is on the order of microseconds to ensure a fast response when an overcurrent signal is generated.

[0064] When resistor R6 is 0, as Figure 1 and Figure 2 In the case shown, the time constants of capacitor C2 and resistor R6 are 0.

[0065] like Figure 7-10 As shown, the circuit in this embodiment includes a dual constant voltage positive power supply and a reference ground GND for providing power to the chips. One 3.3V power supply provides power to the comparator IC1, the main control chip and the driver chips IC2 and IC3 control side, and the other 15V power supply provides power to the high voltage drive side of the driver chips IC2 and IC3.

[0066] A dual comparator IC1 capable of signal comparison processing, such as Figure 7 As shown, the first channel of the comparator compares the overcurrent signal with the threshold voltage value. The current value is converted into a voltage signal by a sampling resistor or current sensor. The three currents are then rectified by diodes D1 and D2 and superimposed. The channel with the highest instantaneous voltage level is active. This voltage is divided by resistors R9 and R10 and sent to the negative input of the comparator. Before entering the comparator, capacitor C5 filters out high-frequency glitches. The processed signal is sent to pin 6 of the negative input. A fixed voltage value is obtained by dividing the voltage between resistors R12 and R11, serving as the threshold voltage for the comparator. This value is filtered by capacitor C6 and sent to pin 5 of the positive input. The comparison result between pins 5 and 6 is output through pin 7. If the voltage level at pin 5 is higher than that at pin 6, pin 7 outputs a high level; if the voltage level at pin 6 is higher than that at pin 5, pin 7 outputs a low level. This indicates excessive current, requiring the overcurrent protection function to be triggered for shutdown protection. The output signal from pin 7 is pulled up by resistor R8, ensuring a high level output from pin 7 when there is no signal, preventing false triggering of the overcurrent protection function. Resistor R7 and capacitor C4 form an RC filter circuit with a filtering time on the order of microseconds. This filter removes interference signals before sending the signal from pin 7 to the controller. When a fault occurs, a low level is sent to notify the controller that an overcurrent signal has been generated, requiring the output to be stopped and software protection to be implemented. The controller protection signal input pins are shown below. Figure 2 .

[0067] The second channel of comparator IC1 establishes the alarm and recovery logic between the overcurrent signal and the hardware driver circuit. The output signal from pin 7 is also sent to the hardware driver protection circuit via the circuit containing diode D3 and resistor R6. Pin 2 of the comparator is pulled up by resistor R5 and remains high under normal conditions. When an overcurrent fault occurs, the level of pin 7 is pulled low, and the charge on capacitor C2 is released through diode D3 and resistor R6. R6 has a very small resistance, serving only as a current limiter to protect the comparator pin, so the charge on C2 can be released quickly, and the level of pin 2 will quickly drop to low. The voltage obtained by the voltage divider between resistors R1 and R2 is a fixed value used as the threshold voltage for comparator 2. After filtering by capacitor C1, this voltage is sent to the positive input pin 3 of the comparator. The comparison result signal between pins 2 and 3 is output through pin 1. If the level at pin 2 is higher than that at pin 3, pin 1 outputs a low level; if the level at pin 3 is higher than that at pin 2, pin 1 outputs a high level. This indicates excessive current, requiring the overcurrent protection function to be triggered for shutdown protection. The output signal at pin 1 is pulled up by resistor R3 to provide a fixed level. At the moment of power-on, the system is unstable, and the driver chip output is disabled. After the power-on moment ends, the comparator output level is determined by the circuit logic. Resistor R4 has a large resistance value and its function is to provide a hysteresis voltage for comparator 2 to prevent the level from jumping back and forth at the critical point. Capacitor C3 stores energy and filters interference from the power supply, providing a clean power supply for comparator chip IC1. The overcurrent signal of comparator 2 is sent to the fault signal pin of the driver chip. When the fault current disappears, pin 7 outputs a high level again, diode D3 acts as a cutoff, and the level at pin 2 can only be restored to a high level by charging capacitor C2 through resistor R5. Since both resistor R5 and capacitor C2 have large values, a charging recovery time in the order of seconds can be obtained, delaying the disappearance of the hardware protection signal. By adjusting the values ​​of resistor R5 and capacitor C2, the fault signal disappearance time of the driver chip can be adjusted to achieve the hardware delay recovery purpose. The threshold value of pin 3 obtained by the voltage divider of R1 and R2 needs to ensure that this level is close to the RC constant value of 63.2%, so that the recovery time of the gate drive overcurrent protection signal can be directly calculated using the filter time constant.

[0068] Three upper bridge arm gate driver chips with protection signal latch-up function. Taking one bridge arm as an example, the gate drive circuit is as follows: Figure 9 , 10As shown. Driver chip IC2 integrates the upper bridge arm driver circuit, and driver chip IC3 integrates the lower bridge arm driver circuit. There are a total of three symmetrical upper and lower bridge arm driver circuits. The upper bridge arm driver circuit needs to have the function of receiving fault signals and internally locking the output, while the lower bridge arm driver circuit does not have this requirement. Pins 1 and 4 of the driver chip are power supply pins. The connected capacitor C9 stores energy and filters out interference on the power supply, providing clean power to driver chip IC2. Pin 2 is the PWM control signal pin, receiving the PWM signal from the controller. The capacitor C8 has a very small capacitance value and is used to filter out interference signals on the PWM signal. Pin 3 receives the fault signal transmitted by the hardware protection current. It is active high and can lock the output signal, cut off the output, and protect the circuit. Pins 5 and 8 are the power supply pins on the driver side, powered by 15V. Capacitor C10 stores energy and filters out interference on the 15V power supply, providing clean power to the output driver terminal of driver chip IC2. Capacitor C11 stores energy, providing 15V power to the gate signal of the switching transistor for turn-on. When the lower bridge arm is on, the 15V power supply charges C11 through resistor R13 and diode D4. R13 limits the current, preventing excessive charging current that could pull the 15V power supply low. Diode D4 reverse-biased cutoff; when the lower bridge arm is off and the upper bridge arm is on, the voltage at pin 5 is raised, much higher than 15V. Diode D4 prevents capacitor C11 from charging C10 in reverse, causing a voltage drop that would prevent the switching transistor's gate from turning on. Pin 6 is the turn-on signal for the switching transistor, providing the turn-on voltage to the gate through resistor R15. Resistor R15 limits the turn-on current, preventing gate voltage oscillations caused by surges. Pin 7 is the turn-off signal for the switching transistor; the gate discharges through resistor R14, turning off the transistor. Resistor R14 limits the turn-off current, preventing excessive interference signals from the switching transistor to the power supply due to rapid turn-off. The function of resistor R16 is to provide a path between the gate and source of the switching transistor, acting as a pull-down resistor to prevent false turn-on. The function of Zener diode ZD1 is to clamp the transistor, preventing excessive voltage between the gate and source from burning out the switching transistor.

[0069] The driver chip IC3 integrates the lower bridge arm driver circuit, directly powered by a 15V power supply. Pin 1 is the PWM control signal pin, receiving the PWM signal from the controller. Capacitor C12 is used to filter out interference signals on the PWM signal. Pins 2 and 5 of the driver chip are power supply pins. The connected capacitor C13 stores energy and filters out interference on the power supply, providing a clean power supply for driver chip IC2. Pins 3 and 4 are the switching signals for the gate of the switching transistor. When turned on, a turn-on voltage is provided to the gate of the switching transistor through resistor R18. Resistor R18 limits the turn-on current to prevent gate voltage oscillation caused by surges. When turned off, the gate of the switching transistor discharges through resistors R17 and R18, turning off the switching transistor. Resistors R17 and R18 are connected in parallel to limit the turn-off current, preventing the switching transistor from generating too much interference signal to the power supply due to too fast turn-off. A fast switching speed of the switching transistor can reduce losses, but it will introduce interference. Therefore, it is designed to turn on slowly and turn off quickly. Therefore, a discharge resistor is added during turn-off to reduce the discharge resistance and accelerate the discharge. The function of diode D5 is to reverse-bias the current through R17 when it is turned on, rendering R17 ineffective; and to conduct when it is turned off, allowing the turn-off current to flow through R17 for faster discharge. The function of resistor R19 is to provide a path between the gate and source of the switching transistor, acting as a pull-down resistor to prevent false turn-on. The function of Zener diode ZD2 is to clamp the transistor, preventing excessive voltage between the gate and source, which could burn out the switching transistor.

[0070] The current detection circuit mainly consists of the right-side comparator of comparator IC1, resistors R7, R8, R9, R10, R11, and R12, capacitors C4, C5, and C6, and diodes D1 and D2. D1, D2, R9, R10, and C5 form a current signal sampling circuit to acquire current information. R11, R12, and C6 form a voltage divider circuit to obtain the overcurrent protection voltage threshold, allowing the setting of the current protection value. R7, R8, and C4 form the output circuit, ensuring a stable high-level output signal when there is no signal, and also conditioning the output signal before sending it to the controller. This can trigger software protection.

[0071] The circuit features different charge and discharge time constants, primarily composed of resistors R5, R6, diode D3, and capacitor C2. The discharge circuit time constant is determined by C2 and R6; the small resistance of R6 allows for a relatively small operating time constant, enabling a rapid response and triggering the gate driver's hardware protection in the event of an overcurrent fault. The charging circuit time constant is also determined by R5 and C2; the larger values ​​of R5 and C2 provide a recovery time constant on the order of seconds, allowing the hardware overcurrent signal to persist for several seconds, preventing the hardware circuit from immediately resuming operation after an overcurrent fault. Diode D3, with its unidirectional conduction and reverse cutoff characteristics, ensures that the two time constants operate independently without interference.

[0072] The comparator circuit with an adjustable time constant mainly consists of the comparator IC1 (left side), resistors R1, R2, R3, R4, and capacitor C1. R1, R2, and C1 form a voltage divider circuit, controlling the recovery time through voltage division. For reliable performance and simplified calculation, the threshold voltage is set to 63.2% of the chip voltage, perfectly matching the commonly used RC filter time constant, ensuring the recovery time of the hardware protection signal is the same as the filter time constant formed by R5 and C2. R3 and R4 form the output circuit, ensuring a normally high output level while providing hysteresis voltage to guarantee output signal stability.

[0073] Three-channel driver chips with fault signal latch-up function. Taking one channel as an example, it mainly consists of IC2, R13, R14, R15, R16, C8, C9, C10, C11, D4, and ZD1. C8 forms a PWM signal filtering circuit to ensure the stability of the control signal. R13, C11, and D4 form a bootstrap circuit, which charges C11 when the lower bridge arm is turned on and provides power to the gate of the switching transistor through C11 when the upper bridge arm is turned on. R14, R15, R16, and ZD1 form a driver output circuit, which controls the turn-on and turn-off speeds of the switching transistor through different turn-on and turn-off resistors. At the same time, R16 and ZD1 form a clamping circuit to prevent false turn-on and damage to the switching transistor due to excessive gate voltage.

[0074] The key points of this plan are as follows: 1. The protection circuit of this solution can send a conventional overcurrent alarm signal with a very short delay to the controller via one channel.

[0075] 2. This solution can send another overcurrent protection signal with extremely low delay to the driver chip.

[0076] 3. This solution can realize the hardware delay protection signal function of the fault signal sent to the driver chip after the fault disappears, with a delay of seconds.

[0077] 4. This solution has a simple circuit with only one comparator and is inexpensive.

[0078] 5. The rise and fall times of this circuit can be controlled separately, making it suitable for different driver chips and flexible and reliable.

[0079] This solution can both acquire overcurrent protection signals and send them to the controller and driver chip, and also delay fault signal recovery, ensuring that both software and hardware continuously receive fault signals, while the fault signal received by the hardware gate driver will not recover in a short time. The protection circuit can implement conventional overcurrent signal alarm and delayed recovery functions, and the circuit is simple, consisting of only one comparator, making it inexpensive. Furthermore, the rise and fall times of the hardware protection signal can be controlled separately, offering flexibility and reliability.

[0080] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An air conditioner, comprising: A current detection circuit is used to detect the current and output an overcurrent signal to the controller when the current exceeds a set current value. The controller is configured to output a driver chip control signal when no overcurrent signal is received, and to stop outputting the driver chip control signal when the overcurrent signal is received. A driver chip is used to receive control signals from the driver chip and drive the compressor; The air conditioner is characterized in that it further includes: The comparator has its first input terminal connected to a reference voltage and its output terminal outputting a signal to the driver chip. Diode D3, the anode of the diode is connected to the second input terminal of the comparator, and its cathode is connected to the overcurrent signal output terminal of the current detection circuit; The overcurrent disappearance delay circuit includes a capacitor C2 and a resistor R5 connected in series between the power supply and ground. The second input terminal of the comparator is connected between the capacitor C2 and the resistor R5. The capacitor C2 and the resistor R5 form a charging circuit. The time constant of the capacitor C2 and the resistor R5 is on the order of seconds. The air conditioner also includes a resistor R6, which is connected between the diode and the overcurrent signal output terminal of the current detection circuit. The capacitor C2 and the resistor R6 form a discharge circuit, and the time constant of the capacitor C2 and the resistor R6 is on the order of microseconds.

2. The air conditioner according to claim 1, characterized in that, The air conditioner includes resistors R1 and R2 connected in series. The reference voltage is obtained by dividing the voltage of resistors R1 and R2. One end of the series resistors R1 and R2 is connected to the power supply, and the other end is grounded. The first input terminal of the comparator is connected between resistors R1 and R2, wherein R2 / (R1+R2) is between 60% and 65%.

3. The air conditioner according to claim 1, characterized in that, The air conditioner includes a resistor R4, which is connected between the first input and output terminals of the comparator. The resistor R4 is used to provide a hysteresis voltage for the comparator.

4. The air conditioner according to claim 1, characterized in that, The output of the comparator is connected to either a pull-up resistor R3 or a pull-down resistor. The pull-up resistor R3 is connected to the power supply, and the pull-down resistor is grounded.

5. The air conditioner according to claim 4, characterized in that, The overcurrent signal output terminal of the current detection circuit is connected to a pull-up resistor R8 or a pull-down resistor. The pull-up resistor R8 is connected to the power supply, and the pull-down resistor is grounded.

6. The air conditioner according to claim 1, characterized in that, The air conditioner includes a charging and discharging circuit consisting of a capacitor C4 and a resistor R7. The overcurrent signal output terminal of the current detection circuit is connected to the charging and discharging circuit consisting of the capacitor C4 and the resistor R7. The resistor R7 is connected in series with the overcurrent signal output terminal of the current detection circuit, and the capacitor C4 is grounded.

7. The air conditioner according to claim 6, characterized in that, The time constants of the capacitor C4 and the resistor R7 are in the microsecond range.

8. The air conditioner according to claim 1, characterized in that, The current detection circuit includes: A rectifier circuit is used to convert alternating current into direct current. The first voltage divider circuit includes resistors R9 and R10 connected in series. Resistor R9 is connected to the output of the rectifier circuit, and resistor R10 is grounded. The second voltage divider circuit includes resistors R12 and R11 connected in series, wherein resistor R12 is connected to the power supply and resistor R11 is grounded. The second comparator has its first input terminal connected between resistors R12 and R11, its second input terminal connected between resistors R9 and R10, and its output terminal being the overcurrent signal output terminal of the current detection circuit.

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