Compressor inverter overcurrent protection circuit and air conditioner

Abstract

The utility model relates to a kind of compressor inverter overcurrent protection circuit and air conditioner, belong to air conditioning technical field, including rectifier unit, sampling resistance, main control chip, overcurrent protection control switch, fault state self-locking maintenance switch, operational amplifier and voltage comparator.Sampling resistance gathers DC bus voltage signal, after amplification by operational amplifier, it is transmitted to the analog-digital conversion pin and voltage comparator of main control chip.Signal is compared with preset threshold by voltage comparator, low level is output when over threshold, makes overcurrent protection control switch open, rectifier unit is disabled;While fault state self-locking maintenance switch is turned on, and fault pin is locked as low level, realizes overcurrent protection and self-locking.The circuit cooperates by hardware and software, quickly responds overcurrent fault and prevents false restart, improves the security and reliability of air conditioning system.

Description

Technical Field

[0001] This application relates to the field of air conditioning technology, and in particular to a compressor inverter overcurrent protection circuit and an air conditioner. Background Technology

[0002] An air conditioner is a device that artificially adjusts air parameters (temperature, humidity, cleanliness, airflow speed, etc.) in an enclosed space to meet human comfort or process requirements. Its core working principle is based on the vapor compression refrigeration cycle (some models also have a heating function), and it mainly consists of four major components: a compressor, a condenser, an evaporator, and a throttling device, as well as a fan and a control system.

[0003] To improve energy efficiency, modern air conditioners commonly employ DC inverter technology in their compressor motors. In traditional DC inverter solutions, the circuit hardware often uses IPM (Intelligent Power Module) modules—these modules integrate driver chips and IGBT power devices, offering relatively simple operation and built-in overcurrent protection. However, IPM modules have significant drawbacks: firstly, their high cost hinders control over overall production costs; secondly, their fixed package size and inflexible circuit topology make them unsuitable for different power levels or customized design requirements, limiting their application in diverse scenarios.

[0004] In existing technologies, the overcurrent protection scheme for inverter compressors in air conditioners often employs an integrated power module combined with sampling and control circuits to achieve the protection function. A typical design involves: acquiring the output current of the power module through a current sampling element; the main control chip (MCU) sets the protection threshold and outputs a control signal; and a dedicated protection circuit unit generates a protection command based on the sampled current and the control signal, thereby achieving overcurrent protection for the power module and demagnetization protection for the compressor.

[0005] However, these existing solutions have obvious technical limitations:

[0006] First, the protection mechanism is simple, relying solely on the one-way control link between the protection circuit unit and the MCU to complete the protection. It lacks redundancy design and is prone to protection failure due to signal interference or single-point faults under complex working conditions, resulting in insufficient reliability.

[0007] Secondly, it lacks a fault state self-locking function. When the overcurrent fault disappears briefly, the system may be restarted without investigation. This not only fails to completely resolve the potential fault, but also exacerbates equipment wear due to repeated start-stop cycles. It has significant defects in the safety of fault handling and the controllability of restart.

[0008] Meanwhile, existing solutions are limited by the fixed architecture of integrated modules, making it difficult to flexibly adjust the circuit topology according to different power requirements, and the overall cost is high, which is not conducive to promotion in diverse application scenarios. Utility Model Content

[0009] This utility model at least partially solves one of the technical problems in related technologies. Therefore,

[0010] According to an embodiment of this disclosure, a compressor inverter overcurrent protection circuit is provided, comprising:

[0011] The rectifier unit is used to convert DC voltage into three-phase AC frequency converter voltage; it has a switching control terminal for receiving disable / enable signals;

[0012] A sampling resistor, connected in series with the DC bus, is used to acquire voltage signals in real time.

[0013] The main control chip includes analog-to-digital conversion pins and fault pins;

[0014] An overcurrent protection control switch includes a first control terminal, a first collecting terminal, and a first transmitting terminal, wherein the first collecting terminal is connected to the switch control terminal, and the first transmitting terminal is grounded.

[0015] A fault-state self-locking sustaining switch includes a second control terminal, a second collecting terminal, and a second transmitting terminal. The second control terminal is connected to the switch control terminal, and the second transmitting terminal is grounded.

[0016] An operational amplifier is used to acquire the voltage signal across the sampling resistor and transmit the amplified voltage signal to the analog-to-digital converter pin.

[0017] A voltage comparator is used to acquire the voltage signal amplified by the operational amplifier and compare the amplified voltage signal with a preset voltage threshold. When the voltage signal amplified by the operational amplifier is greater than the preset voltage threshold, the voltage comparator outputs a low level to the first control terminal, the second collection terminal, and the fault pin; otherwise, the voltage comparator outputs a high level.

[0018] When the overcurrent protection circuit is in overcurrent protection state: the voltage comparator outputs a low level, the overcurrent protection control switch is disconnected because the first control terminal is low, so that the switch control terminal is set to a high level, and the rectifier unit is thus disabled; at the same time, the fault state self-locking maintenance switch is turned on because the second control terminal is high, thereby locking the fault pin to a low level.

[0019] In the above embodiments, this application provides a voltage comparator. When the voltage signal amplified by the operational amplifier is greater than a preset voltage threshold, it can simultaneously trigger hardware protection (disabling the rectifier unit through the overcurrent protection control switch) and software protection (triggering the main control chip through the fault pin), forming a hardware and software collaborative protection, avoiding protection failure caused by single point of failure and single protection mechanism, and improving reliability.

[0020] In the above embodiments, this application uses a fault state self-locking maintenance switch to lock the fault pin to a low level in the overcurrent protection state, preventing the system from being restarted directly without investigation after the overcurrent fault has temporarily disappeared, avoiding the aggravation of equipment wear due to repeated start-stop, solving the problem of lacking fault state self-locking function, and improving the safety of fault handling and restart controllability.

[0021] In the above embodiments, this application uses discrete components to build the circuit instead of an integrated IPM module, which allows for flexible configuration of the topology to adapt to different power requirements, reduce costs, and avoid the limitations of high cost and fixed topology of IPM modules.

[0022] This application also provides a compressor inverter overcurrent protection circuit, including:

[0023] The rectifier unit is used to convert DC voltage into three-phase AC frequency converter voltage; it has a switching control terminal for receiving disable / enable signals;

[0024] A sampling resistor, connected in series with the DC bus, is used to acquire voltage signals in real time.

[0025] The main control chip includes analog-to-digital conversion pins and fault pins;

[0026] An overcurrent protection control switch has a first control terminal, a first collecting terminal and a first transmitting terminal, wherein the first collecting terminal is connected to the switch control terminal and the first transmitting terminal is grounded;

[0027] A fault-state self-locking sustaining switch has a second control terminal, a second collecting terminal, and a second transmitting terminal. The second control terminal is connected to the switch control terminal, and the second transmitting terminal is grounded.

[0028] An operational amplifier includes a first input terminal, a second input terminal, and a first output terminal. The first input terminal and the second input terminal are respectively connected to the two ends of the sampling resistor, and the first output terminal is connected to the analog-to-digital conversion pin.

[0029] A voltage comparator includes a third input terminal, a fourth input terminal, and a second output terminal. The third input terminal is connected to the first output terminal, and the fourth input terminal is used to acquire a preset voltage threshold. The second output terminal is connected to the first control terminal, the second collection terminal, and the fault pin, respectively. The voltage comparator compares the preset voltage threshold with the voltage signal amplified by the operational amplifier. When the voltage signal amplified by the operational amplifier is greater than the preset voltage threshold, the second output terminal outputs a low level; otherwise, the second output terminal outputs a high level.

[0030] When the overcurrent protection circuit is in overcurrent protection state: the voltage comparator outputs a low level, the overcurrent protection control switch is disconnected because the first control terminal is low, so that the switch control terminal is set to a high level, and the rectifier unit is thus disabled; at the same time, the fault state self-locking maintenance switch is turned on because the second control terminal is high, thereby locking the fault pin to a low level.

[0031] In some embodiments of this application, the overcurrent protection circuit further includes:

[0032] The system restart control switch has a third control terminal, a third collection terminal, and a third transmission terminal. The third control terminal is connected to the disable pin of the main control chip, the third collection terminal is connected to the switch control terminal, and the third transmission terminal is grounded.

[0033] When the overcurrent protection circuit is activated: the disable pin outputs a high level, the system restart control switch is turned on because the third control terminal is high, pulling the switch control terminal low, so that the rectifier unit enters normal operation; after the rectifier unit is running normally, the disable pin switches to output a low level; at the same time, the voltage comparator outputs a high level, the overcurrent protection control switch is turned on because the third control terminal is high, and the fault state self-locking maintenance switch is turned off because the switch control terminal is low.

[0034] In the above embodiments, this application sets a system restart control switch, which is controlled to be turned on / off by the disable pin of the main control chip. The restart logic of "disable pin high level → switch on → rectifier unit enabled" is clearly defined, so as to realize the system restart controllable and avoid the problems of poor restart controllability and direct accidental start without investigation in the existing solution. At the same time, the state switching sequence from startup to normal operation is clearly defined (disable pin switches from high level to low level) to ensure stable transition of circuit operation and improve operational reliability.

[0035] In some embodiments of this application, the overcurrent protection control switch, the fault state self-locking maintenance switch, and the system restart control switch are all transistors or metal-oxide-semiconductor field-effect transistors.

[0036] In the above embodiments, this application specifies that the overcurrent protection control switch, the fault state self-locking maintenance switch, and the system restart control switch can be transistors or metal-oxide-semiconductor field-effect transistors (MOSFETs). Both devices are general-purpose discrete components and can be flexibly selected according to actual power and frequency requirements.

[0037] In some embodiments of this application, the rectifier unit includes multiple power switching devices and multiple driver chips; the multiple power switching devices form a three-phase bridge arm topology, with each phase upper bridge arm connected to the positive terminal of the DC bus voltage and each phase lower bridge arm connected to the negative terminal of the DC bus voltage through the sampling resistor; each driver chip is configured to independently drive a single power switching device or share the driving of multiple power switching devices in the same bridge arm group.

[0038] In the above embodiments, in the rectifier unit of this application, the power switching devices constitute a three-phase bridge arm, and the driver chip can independently drive a single device or share the same bridge arm group, supporting the adjustment of the driving mode according to the power level (shared driving for low power and independent driving for high power), avoiding the defects of fixed topology and inflexible adjustment of IPM module; the lower bridge arm is connected to the negative terminal of the bus through a sampling resistor, so that the sampling resistor is directly connected in series in the main circuit, ensuring accurate current sampling, providing a reliable signal for overcurrent protection, and improving protection accuracy.

[0039] In some embodiments of this application, the power switching device may be an insulated gate bipolar transistor or a metal-oxide-semiconductor field-effect transistor.

[0040] In the above embodiments, this application specifies that the power switching device can be IGBT or MOSFET. IGBT is suitable for medium and high voltage / high power scenarios, while MOSFET is suitable for medium and low voltage / high frequency scenarios. It can be flexibly selected according to the power requirements of the compressor to adapt to compressors of different power levels and improve the compatibility and flexibility of circuit design.

[0041] In some embodiments of this application, a capacitor is provided between the positive terminal of the DC bus voltage and the negative terminal of the DC bus voltage.

[0042] In the above embodiments, this application provides a capacitor between the positive and negative terminals of the DC bus, which can absorb bus voltage fluctuations (such as ripple generated by high-frequency switching of switching devices), reduce the interference of voltage ripple on power switching devices and sampling signals, stabilize the DC bus voltage, reduce the impact of voltage spikes on devices, extend device life, and improve circuit operation stability.

[0043] In some embodiments of this application, the driver chip includes a disable / enable pin, the disable / enable pins of each driver chip are connected together, and multiple driver chips are controlled by the same control signal.

[0044] In the above embodiments, this application connects the disable / enable pins of all driver chips and controls them with the same control signal, ensuring that all power switching devices are disabled simultaneously during overcurrent, avoiding local overcurrent or damage caused by some devices not being turned off in time, and solving the problem of insufficient protection reliability in existing solutions; at the same time, it simplifies the control logic, reduces wiring complexity, reduces the risk of signal interference, and improves the circuit's anti-interference capability.

[0045] In some embodiments of this application, each of the power switching devices is connected in antiparallel to a diode.

[0046] In the above embodiments, the present application provides an anti-parallel diode for each power switching device, which can provide a freewheeling path for the induced current of the motor load when the device is turned off, avoiding reverse voltage breakdown of the device; when the compressor motor brakes or performs energy feedback, it guides the reverse current back to the bus, avoiding circuit overvoltage, protecting the power switching device, and improving system safety.

[0047] In addition, this application also provides an air conditioner, including a housing, in which a compressor and the overcurrent protection circuit are disposed;

[0048] The compressor is connected to the overcurrent protection circuit, which is used to drive or disable the compressor.

[0049] In the above embodiments, after the air conditioner of this application is equipped with the overcurrent protection circuit, the compressor can achieve hardware and software collaborative protection, fault self-locking and controllable restart, avoiding compressor damage or safety accidents caused by overcurrent, and solving the risk of protection failure of existing solutions; at the same time, the circuit cost is lower than the IPM solution, and it can be adapted to compressors of different power, making the air conditioner more advantageous in cost control and diversified needs (such as different horsepower, customized scenarios), solving the problems of high cost and limited promotion of existing solutions, and improving product competitiveness.

[0050] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0051] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art 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.

[0052] Figure 1 This is a circuit diagram of one embodiment of an overcurrent protection circuit provided in this application.

[0053] Figure 2This is a circuit diagram illustrating the configuration relationship between the driver chip and the power switching device provided in this application, as shown in Embodiment 1.

[0054] Figure 3 This is a circuit diagram of Embodiment 2 of the configuration relationship between the driver chip and the power switching device provided in this application.

[0055] Figure 4 This is a schematic diagram of the connection circuit of the driver chip, power switching device and diode provided in this application.

[0056] Figure 5 This is a schematic diagram of the circuit for triggering software protection provided in this application.

[0057] Figure 6 This is a schematic diagram of the triggering hardware protection circuit provided in this application.

[0058] Figure 7 This is a circuit diagram of the hardware protection section and rectifier unit provided in this application.

[0059] Figure 8 This is a circuit diagram of the system restart control switch, main control chip, and rectifier unit provided in this application.

[0060] Figure 9 This is a flowchart of the operation of each device after the overcurrent protection is triggered, as provided in this application.

[0061] Figure 10 This is a flowchart of the operation of each device after the overcurrent protection circuit provided in this application is restarted.

[0062] In the above figures:

[0063] A1, Operational amplifier;

[0064] A2, Voltage comparator;

[0065] C1, capacitor;

[0066] D1~D6, diodes;

[0067] Q1~Q6, power switching devices;

[0068] Q7. Overcurrent protection control switch;

[0069] Q8. Fault condition self-locking maintenance switch;

[0070] Q9. System restart control switch;

[0071] R1, sampling resistor;

[0072] U1~U6, driver chips;

[0073] MCU, main control chip. Detailed Implementation

[0074] To make the objectives, technical solutions, and advantages of this application clearer, the application is described and illustrated below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application. All other embodiments obtained by those skilled in the art based on the embodiments provided in this application without inventive effort are within the scope of protection of this application.

[0075] Obviously, the accompanying drawings described below are merely some examples or embodiments of this application. Those skilled in the art can apply this application to other similar scenarios based on these drawings without any inventive effort. Furthermore, it is understood that although the efforts made in this development process may be complex and lengthy, for those skilled in the art related to the content disclosed in this application, any changes to design, manufacturing, or production based on the technical content disclosed in this application are merely conventional technical means and should not be construed as insufficient disclosure of the content of this application.

[0076] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0077] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0078] In this utility model, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0079] In this utility model, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this utility model. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples. Additionally, the word "and / or" appearing throughout the text means including three parallel solutions; for example, "A and / or B" includes solution A, solution B, or a solution that simultaneously satisfies A and B.

[0080] The air conditioner involved in this application performs a refrigeration cycle by using a compressor, condenser, expansion valve, and evaporator. The refrigeration cycle includes a series of processes involving compression, condensation, expansion, and evaporation, and supplies refrigerant to the conditioned and heat-exchanged air.

[0081] The compressor compresses refrigerant gas under high temperature and pressure 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.

[0082] The expansion valve expands the high-temperature, high-pressure liquid refrigerant condensed in the condenser into a low-pressure liquid refrigerant. The evaporator evaporates the expanded refrigerant in the expansion valve, 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.

[0083] 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 an expansion valve can be provided in either the indoor or outdoor unit.

[0084] 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.

[0085] To improve energy efficiency, modern air conditioners commonly employ DC inverter technology in their compressor motors. In existing technology, a typical overcurrent protection scheme for the inverter compressor in an air conditioner involves: sampling the output current of the power module using a current sampling element; the main control chip (MCU) sets a protection threshold and outputs a control signal; and a dedicated protection circuit unit generates a protection command based on the sampled current and the control signal, thus achieving overcurrent protection for the power module and demagnetization protection for the compressor. However, this existing scheme has significant technical limitations: a simplistic protection mechanism and a lack of fault-locking functionality.

[0086] To solve the aforementioned technical problems, see attached... Figures 1-10 As shown, this application discloses a compressor inverter overcurrent protection circuit.

[0087] As attached Figure 1 As shown in an illustrative embodiment of this application, the overcurrent protection circuit includes a rectifier unit, a sampling resistor R1, a main control chip MCU, an overcurrent protection control switch Q7, a fault state self-locking maintenance switch Q8, an operational amplifier A1, and a voltage comparator A2. Each part will be described in detail below.

[0088] The rectifier unit is the "power drive core" of the compressor. Its output three-phase AC variable frequency voltage directly supplies the compressor's motor windings, driving the motor. The rectifier unit's operating state (enabled / disabled) directly determines the compressor's operating state—when enabled, it outputs three-phase voltage to drive the compressor; when disabled (e.g., during overcurrent protection), the output is interrupted, and the compressor stops running. Therefore, the rectifier unit is a crucial intermediate module connecting the DC power supply and the compressor motor, responsible for converting electrical energy into power to drive the compressor as needed. It is also the core control object of the overcurrent protection circuit (by disabling the rectifier unit, the compressor can be shut down for emergency protection).

[0089] The rectifier unit has a switch control terminal, which is used to receive disable / enable signals. The switch control terminal can be a pin for external circuit connection in a physical sense, or it can be an electrical connection node of multiple driver chip disable / enable pins (i.e. a common control node formed by connecting the ENB pins of all driver chips through wires), or a logic level convergence point in the driver circuit used to summarize control signals.

[0090] like Figure 2 , 3 As shown, the rectifier unit includes multiple power switching devices and multiple driver chips; the multiple power switching devices form a three-phase bridge arm topology, and the upper bridge arm of each phase is connected to the positive terminal of the DC bus voltage (i.e., Figure 1 In the DC+ phase, each lower bridge arm is connected to the negative terminal of the DC bus voltage (i.e., DC+) through the sampling resistor R1. Figure 1 (DC-); Each driver chip is configured to independently drive a single power switch device, or to share the drive of multiple power switch devices in the same bridge arm group.

[0091] In some embodiments, the power switching device may be an insulated gate bipolar transistor.

[0092] The Insulated Gate Bipolar Transistor (IGBT) consists of a gate (G), an emitter (E), and a collector (C). Its conduction is controlled by the gate voltage. When on, it relies on minority carriers for conduction and can withstand relatively high voltage and current. It combines the voltage control advantages of a MOSFET with the high current carrying capacity of a BJT, achieving a switching speed between the two, making it suitable for medium-to-high voltage and high-current applications. In this embodiment, the gate of the IGBT is the control terminal, used to receive control signals from the driver chip. Specifically, the driver chip applies a voltage to the IGBT through the gate (G) pin, controlling the conduction state between its collector (C) and emitter (E).

[0093] In some embodiments, the power switching device may be a metal-oxide-semiconductor field-effect transistor.

[0094] A metal-oxide-semiconductor field-effect transistor (MOSFET) consists of a gate (G), a source (S), and a drain (D). Applying a voltage to the gate creates an electric field, controlling the conduction path (N-type or P-type) between the source and drain to turn on or off. Its characteristics include voltage-controlled current, extremely high input impedance (almost no control current consumption), and fast switching speed, making it suitable for high-frequency applications. In this embodiment, the gate of the MOSFET is the control terminal, used to receive control signals from the driver chip. Specifically, the driver chip applies a voltage to the MOSFET through the gate (G) pin, controlling the conduction state between its collector (C) and emitter (E).

[0095] Naturally, the power switching device can also be other power switching devices with similar functions, and this application does not impose any restrictions on them.

[0096] In some embodiments, the driver chips are configured with a disable / enable pin (i.e., ENB pin) for receiving external disable or enable commands and a drive pin for controlling the power switching device to turn on and off.

[0097] To achieve synchronous control of all power switching devices in the rectifier unit, the disable / enable pins of each driver chip are directly connected to the switch control terminal via wires, or the disable / enable pins of each driver chip are first connected to form a common control node and then connected to the switch control terminal, so that multiple driver chips can receive and respond to the same control signal.

[0098] When a high-level signal is input to the switch control terminal, all the disable / enable pins of the driver chips simultaneously receive a high level, and the driver chips immediately enter the disabled state, ceasing to output drive signals to the power switching devices, ensuring that all power switching devices are turned off simultaneously. When a low-level signal is input to the switch control terminal, all the disable / enable pins of the driver chips simultaneously receive a low level, and the driver chips switch from the disabled state to the enabled state, resuming the output drive signal and controlling the power switching devices to operate according to preset logic. This design, by unifying the control signal path, ensures the consistency of the operation of the power switching devices in the three-phase bridge arm, avoiding circuit abnormalities caused by delayed responses of some devices (such as direct short circuits between upper and lower bridge arms), while simplifying the wiring design of the external control circuit and improving the system's anti-interference capability.

[0099] Each of the driver chips has its driver pin connected to the control terminal of a single power switch device, or simultaneously connected to the control terminals of multiple power switch devices in the same bridge arm group.

[0100] Specifically, the connection between the driver chip's driver pins (i.e., gate driver pins) and the power switching device has two configuration modes to adapt to the needs of different application scenarios:

[0101] 1) Independent drive mode: such as Figure 2 As shown, in this mode, the drive pin of each driver chip is connected to the control terminal of only one power switching device (for example, the gate drive pin of driver chip U1 is directly connected to the gate G1 of power switching device Q1). This configuration has advantages such as fault isolation (when a fault such as a short circuit occurs in a single device, only the corresponding driver chip is affected, avoiding impact on other devices) and precise control (drive parameters can be adjusted independently for each device).

[0102] 2) Shared driver mode: such as Figure 3 As shown, in this mode, the drive pins of the same driver chip are connected to multiple power switching devices in the same bridge arm group through logic circuit branches (for example, the same output pin of driver chip U2 is simultaneously connected to the gate G1 of Q1 and the gate G2 of Q2). This configuration achieves safe driving through mechanisms such as interlock logic (interlock circuits are integrated inside the driver chip to ensure that the upper and lower transistors (such as Q1 and Q2) in the same bridge arm group will not be turned on at the same time to prevent shoot-through short circuits) and time-division driving (through timing control, the upper and lower transistors receive drive signals at different times (such as Q2 being forcibly turned off when Q1 is turned on)).

[0103] Regardless of the mode used, the enable / disable pins (ENB) of the driver chips remain connected in parallel to ensure that all driver chips respond synchronously when overcurrent protection is triggered, quickly cutting off the drive signal to the power switching devices. This design ensures both system flexibility and consistency of the protection mechanism.

[0104] Furthermore, the core functions of the driver chip (such as receiving external control signals, amplifying drive current to drive power devices, integrating disable / enable pins for state control, and building-in basic protection logic) are standard configurations well-known to those skilled in the art. Its pin definitions (such as drive output pins and ENB disable / enable pins), electrical parameters, and interface design all follow industry-standard specifications. In the existing technology, mature driver chip products such as the Infineon 2ED series and TI UCC series have been widely used in similar inverter circuits, and their working principles and usage methods are self-evident to those skilled in the art.

[0105] Therefore, the selection of the driver chip, the connection method, and the implementation of its basic functions in this application are all conventional technical means that can be understood and implemented by those skilled in the art based on existing technical knowledge, and do not require further details. Those skilled in the art can clearly understand its specific configuration and operating logic.

[0106] In some embodiments, each of the power switching devices is connected in anti-parallel with a diode, such as... Figure 4 As shown.

[0107] "Anti-parallel connection" refers to connecting a diode and a power switching device (such as an IGBT or MOSFET) in reverse parallel. Specifically, the anode of the diode is connected to the emitter of the power switching device (such as the emitter of an IGBT or the source of a MOSFET), and the cathode of the diode is connected to the collector of the power switching device (such as the collector of an IGBT or the drain of a MOSFET), forming a circuit structure in reverse parallel connection.

[0108] The main advantages of this design are as follows: First, it provides a freewheeling path for inductive loads. When the power switching devices are turned off, the inductive load generates a reverse induced electromotive force. The anti-parallel diodes then conduct, allowing the current to flow continuously and decay slowly, preventing damage to the devices due to excessive voltage caused by sudden current changes. Second, it plays a rectification role in alternating current scenarios. For example, in three-phase bridge topologies such as inverters and rectifiers, when the power switching devices are turned off and the AC voltage direction is opposite, the diodes can naturally conduct, allowing the current to flow in reverse and achieving functions such as energy feedback. Third, it protects the power switching devices. Through the aforementioned freewheeling and rectification effects, it effectively prevents the devices from being damaged by overvoltage and current surges, ensuring stable circuit operation. This design is crucial for maintaining reliable system operation, especially in applications such as motor drives and power conversion.

[0109] In some embodiments, the rectifier unit includes six IGBTs (in Figure 1 The diodes are labeled Q1, Q2, Q3, Q4, Q5, and Q6 respectively, and six anti-parallel diodes (in...). Figure 1 These correspond to D1, D2, D3, D4, D5, and D6 respectively, where each IGBT forms an anti-parallel structure with its corresponding anti-parallel diode; in terms of driving method, each IGBT can be configured with an independent driving chip (in... Figure 1 The IGBTs are labeled U1, U2, U3, U4, U5, and U6 respectively. Alternatively, a single-bridge driver chip can be used for both upper and lower bridge arms. Both configuration modes can effectively drive the IGBTs. The disable / enable pins (ENB) of all driver chips are interconnected to form a unified control node, ensuring that the driver chips can synchronously receive disable or enable signals. The six IGBTs are combined in a three-phase bridge arm topology, specifically forming three upper and lower bridge arms (U-phase upper bridge arm is Q1 and lower bridge arm is Q2, V-phase upper bridge arm is Q3 and lower bridge arm is Q4, and W-phase upper bridge arm is Q5 and lower bridge arm is Q6). The IGBTs of each phase upper bridge arm are directly connected to the positive terminal of the DC bus voltage (DC+), while the IGBTs of each phase lower bridge arm are connected to the negative terminal of the DC bus voltage (DC-) through the sampling resistor R1, thus forming a complete main power circuit.

[0110] The main control chip MCU has three key functional pins: one is the analog-to-digital conversion pin (i.e., Figure 1 The AD pin is used to receive the sampled voltage signal amplified by operational amplifier A1, and to obtain the DC bus current information in real time through analog-to-digital conversion; the second is the fault pin (i.e. Figure 1 The FAULT pin (connected to the output of voltage comparator A2) receives a low-level fault signal when an overcurrent occurs, triggering the software-level overcurrent protection logic; the third is the disabled pin (i.e. Figure 1 The DISABLE pin (in the chip) is used to output a system restart control signal. By controlling the system restart control switch Q9 to turn on and off, it enables active control of the disabled / enabled state of the driver chip. These three pins work together, allowing the main control chip MCU to not only monitor the current status in real time and respond to hardware protection signals, but also intervene in the protection and restart process through software instructions, forming a hardware and software combined overcurrent protection mechanism.

[0111] Furthermore, the basic functions of the main control chip MCU, such as analog-to-digital conversion, pin level detection, and interrupt response, are standard configurations of general-purpose microcontrollers (MCUs), and the related hardware interface design conforms to industry-standard specifications. The overcurrent protection logic at the software level (such as setting overcurrent thresholds, executing stop commands after receiving fault signals, and recording fault status) is a conventional control process that can be implemented by those skilled in the art based on conventional programming logic, without requiring additional creative effort.

[0112] Therefore, this application does not need to elaborate on the specific model, internal structure and software code details of the main control chip MCU. Those skilled in the art, based on existing technical knowledge, can fully understand and implement the above functions.

[0113] The sampling resistor R1 is connected in series with the DC bus. Specifically, the sampling resistor R1 is connected in series in the negative circuit of the DC bus, and its core function is to convert the real-time current signal in the DC bus into a detectable DC voltage signal. When current flows through the sampling resistor R1, according to Ohm's law, a voltage difference proportional to the current will be generated across the resistor. By acquiring this voltage signal, the magnitude of the bus current can be indirectly reflected. This design enables the sampling resistor R1 to capture the current change of the DC bus in real time and accurately, providing a raw and reliable electrical signal basis for subsequent signal amplification and overcurrent judgment.

[0114] The operational amplifier A1 is used to acquire the voltage signal across the sampling resistor R1, amplify the signal, and transmit it to the analog-to-digital conversion pin of the main control chip MCU. The operational amplifier A1 has three key ports: a first input terminal, a second input terminal, and a first output terminal. The first and second input terminals are respectively connected to the two ends of the sampling resistor R1 to obtain the voltage difference across the resistor. The first output terminal is directly connected to the analog-to-digital conversion pin of the main control chip MCU, accurately outputting the amplified voltage signal to the main control chip MCU. This provides a pre-processed electrical signal for subsequent current monitoring and overcurrent detection, such as... Figure 5 As shown.

[0115] The operational amplifier A1, as a fundamental component for signal amplification in the circuit, is a conventional technique known in the art. The basic functions of operational amplifier A1 (such as differential input, signal amplification, and output to the ADC pin), its circuit connection methods (such as connecting the positive and negative input terminals to the sampling resistor R1 and the output terminal to the analog-to-digital converter pin), and parameter configurations (such as gain setting and bias adjustment) are all fundamental knowledge in electronic engineering. Numerous published documents and mature products (such as TI's LM358 and ADI's AD8605) detail its design and application methods. The selection and connection method of operational amplifier A1 in this application follow industry-standard specifications and are readily implementable by those skilled in the art based on conventional technical knowledge. No creative improvements are required, therefore, specific models and circuit details need not be elaborated upon.

[0116] like Figure 7 , 8 As shown, the voltage comparator A2 is used to receive the voltage signal amplified by the operational amplifier A1, and compare the voltage signal amplified by the operational amplifier A1 with a preset voltage threshold (i.e., the set current limit potential L-LIMIT) to determine whether there is an overcurrent. The voltage comparator A2 has three key ports: a third input terminal, a fourth input terminal, and a second output terminal. The third input terminal is connected to the first output terminal of the operational amplifier A1 to obtain the amplified voltage signal. The fourth input terminal is connected to the preset voltage threshold (current limit potential L-LIMIT). The second output terminal is simultaneously connected to the first control terminal of the overcurrent protection control switch Q7, the second collection terminal of the fault state self-locking maintenance switch Q8, and the fault pin of the main control chip MCU to realize the synchronous output of the comparison result.

[0117] The specific working logic is as follows: when the voltage signal amplified by operational amplifier A1 is greater than the preset voltage threshold, voltage comparator A2 determines that it is in an overcurrent state, and the second output terminal outputs a low level. This low level signal synchronously acts on the first control terminal, the second collection terminal, and the fault pin, triggering the hardware overcurrent protection action and the software overcurrent protection of the main control chip MCU; conversely, when the amplified voltage signal is less than or equal to the preset voltage threshold, the second output terminal outputs a high level, and the system maintains normal operating status.

[0118] Furthermore, the core functions of the voltage comparator A2 (such as receiving the signal to be compared and the reference threshold through two input terminals, and outputting high and low levels to reflect the comparison result) are standard functions well-known to those skilled in the art. Its pin definitions (inverting input terminal, inverting input terminal, and output terminal), electrical characteristics, and typical application circuits (such as the threshold comparison circuit in overcurrent detection) all conform to industry-standard specifications. In the prior art, voltage comparators A2 products such as the LM339 and LM393 series have been widely used in signal comparison scenarios of various electronic devices, and their working principles and usage methods are obvious to those skilled in the art.

[0119] Therefore, the selection, connection method and comparison logic of voltage comparator A2 in this application are all conventional technical means that can be understood and implemented by those skilled in the art based on existing technical knowledge, and there is no need for additional details. Those skilled in the art can clearly understand its specific configuration and operation.

[0120] The overcurrent protection control switch Q7 is a three-pin switching device (such as a transistor or MOSFET), and its pin definitions and connections are as follows: a first control terminal for receiving control signals (such as the base of a transistor or the gate of a MOSFET), a first collector terminal as the current path input terminal (such as the collector of a transistor or the drain of a MOSFET), and a first emitter terminal as the current path output terminal (such as the emitter of a transistor or the source of a MOSFET). The first collector terminal is directly connected to the switching control terminal of the rectifier unit, and the first emitter terminal is directly grounded. The power switching device is turned on and off by the level signal received by the first control terminal (such as the high and low level output by voltage comparator A2), thereby realizing hardware-level fast regulation of the disabled / enabled state of the rectifier unit.

[0121] The fault state self-locking maintenance switch Q8 is a switching device with three pins (such as a transistor or MOSFET). Its pin definitions and connection relationships are as follows: a second control terminal for receiving trigger signals, a second collection terminal as the current path input terminal (such as the collector of a transistor or the drain of a MOSFET), and a second emitter terminal as the current path output terminal (such as the emitter of a transistor or the source of a MOSFET).

[0122] Specifically, the second control terminal is connected to the switch control terminal of the rectifier unit to obtain a control signal, the second collection terminal is connected to the fault pin, and the second transmission terminal is directly grounded. When the system triggers overcurrent protection, the fault state self-locking switch Q8 is turned on under the action of the second control terminal signal, thereby locking the fault pin to a low level, ensuring that the rectifier unit remains in a disabled state, and preventing the system from restarting unexpectedly if the fault is not cleared.

[0123] In some embodiments, the overcurrent protection circuit further includes a system restart control switch Q9.

[0124] The system restart control switch Q9 is a three-pin switching device (such as a transistor or MOSFET), and its pin definitions and connections are as follows: a third control terminal for receiving control signals (such as the base of a transistor or the gate of a MOSFET), a third collection terminal as the current input path (such as the collector of a transistor or the drain of a MOSFET), and a third emitter terminal as the current output path (such as the emitter of a transistor or the source of a MOSFET).

[0125] In terms of specific connections, the third control terminal is directly connected to the disable pin of the main control chip MCU, receiving the restart control signal output by the main control chip MCU; the third collection terminal is connected to the switch control terminal of the rectifier unit, and the third transmission terminal is directly grounded. When the overcurrent protection circuit needs to be restarted, the main control chip MCU outputs a valid level signal (such as a high level triggering the transistor to conduct) through the disable pin, turning on the system restart control switch Q9, pulling the potential of the switch control terminal low to ground potential, releasing the disable state of the rectifier unit, thereby realizing the controllable restart of the compressor; during normal operation, the switch remains in the off state and does not affect the normal level logic of the switch control terminal.

[0126] In some embodiments, the overcurrent protection control switch Q7, the fault state self-locking maintenance switch Q8, and the system restart control switch Q9 are all transistors or metal-oxide-semiconductor field-effect transistors (MOSFETs).

[0127] The bipolar junction transistor (BJT) is a three-terminal device made of semiconductor material. It amplifies or switches signals through current control and is one of the basic components of electronic circuits.

[0128] In some embodiments, a capacitor is provided between the positive terminal of the DC bus voltage and the negative terminal of the DC bus voltage.

[0129] Specifically, the working principle of this application is as follows:

[0130] Normal operation: Sampling resistor R1 converts the DC bus current into a voltage signal, which is amplified by operational amplifier A1 and simultaneously transmitted to the analog-to-digital conversion pin of the main control chip MCU (real-time current monitoring) and the third input terminal of voltage comparator A2. Voltage comparator A2 compares the voltage signal amplified by operational amplifier A1 with the preset current limit potential L-LIMIT. If it does not exceed the limit, it outputs a high level, turning on the overcurrent protection control switch Q7. The rectifier unit switch control terminal is grounded (low level) through the overcurrent protection control switch Q7. The disable / enable pins of driver chips U1~U6 are set low, enabling the driver chips. Power switching devices Q1~Q6 operate normally. At the same time, the fault state self-locking switch Q8 is opened due to the low level of the switch control terminal, and the disable pin remains high (no fault). At this time, the disable pin of the main control chip MCU outputs a low level, and the system restart control switch Q9 is in the off state.

[0131] Overcurrent protection triggered: such as Figure 9 As shown, when the bus current is too large and the sampling voltage exceeds L-LIMIT, the voltage comparator A2 outputs a low level to the first control terminal of the overcurrent protection control switch Q7, causing the overcurrent protection control switch Q7 to be turned off. The switch control terminal is set to a high level through the pull-up resistor, and the rectifier unit is disabled. At the same time, the low level output of the voltage comparator A2 triggers the software overcurrent protection logic of the main control chip MCU to the fault pin, and the high level of the switch control terminal turns on the fault state self-locking switch Q8. After the fault state self-locking switch Q8 is turned on, it forcibly pulls the fault pin low, realizing fault self-locking (even if the voltage comparator A2 returns to a high level, the fault pin remains at a low level). The high level of the switch control terminal sets the disable / enable pins of the driver chips U1~U6 high, disabling the driver chips and turning off the power switching devices Q1~Q6.

[0132] System reset and restart: such as Figure 10 As shown, after the fault is cleared, the main control chip MCU sets the disable pin to a high level through software control, which turns on the system restart control switch Q9. The system restart control switch Q9 pulls the switch control terminal low, and the rectifier unit enters normal operation. After the rectifier unit is running normally, the main control chip MCU switches the disable pin to output a low level. At the same time, if the bus current returns to normal, the voltage comparator A2 outputs a high level, which turns on the overcurrent protection control switch Q7. The fault state self-locking maintenance switch Q8 is opened due to the low level of the switch control terminal, releasing the fault pin lock and restoring the system to normal monitoring state.

[0133] This process achieves coordinated operation of hardware protection, fault self-locking, and software-controlled restart through a three-level switch, ensuring that the circuit responds quickly during overcurrent and preventing malfunctions.

[0134] This application also discloses an air conditioner, which includes a housing, a compressor and the overcurrent protection circuit described above are disposed inside the housing; the compressor is connected to the overcurrent protection circuit, and the overcurrent protection circuit is used to drive or disable the compressor.

[0135] For ease of explanation, the above description has been provided in conjunction with specific embodiments. However, the above exemplary discussion is not intended to be exhaustive or to limit the embodiments to the specific forms disclosed above. Various modifications and variations can be obtained based on the above teachings. The selection and description of the above embodiments are for the purpose of better explaining the principles and practical applications, thereby enabling those skilled in the art to better utilize the described embodiments and various different variations of embodiments suitable for specific use considerations.

Claims

1. A compressor inverter overcurrent protection circuit, characterized in that, It includes: The rectifier unit is used to convert DC voltage into three-phase AC frequency converter voltage; It has a switch control terminal for receiving disable / enable signals; A sampling resistor, connected in series with the DC bus, is used to acquire voltage signals in real time. The main control chip includes analog-to-digital conversion pins and fault pins; An overcurrent protection control switch includes a first control terminal, a first collecting terminal, and a first transmitting terminal, wherein the first collecting terminal is connected to the switch control terminal, and the first transmitting terminal is grounded. A fault-state self-locking sustaining switch includes a second control terminal, a second collecting terminal, and a second transmitting terminal. The second control terminal is connected to the switch control terminal, and the second transmitting terminal is grounded. An operational amplifier is used to acquire the voltage signal across the sampling resistor and transmit the amplified voltage signal to the analog-to-digital converter pin. A voltage comparator is used to acquire the voltage signal amplified by the operational amplifier and compare the amplified voltage signal with a preset voltage threshold. When the voltage signal amplified by the operational amplifier is greater than the preset voltage threshold, the voltage comparator outputs a low level to the first control terminal, the second collection terminal, and the fault pin; otherwise, the voltage comparator outputs a high level. When the overcurrent protection circuit is in overcurrent protection state: the voltage comparator outputs a low level, the overcurrent protection control switch is disconnected because the first control terminal is low, so that the switch control terminal is set to a high level, and the rectifier unit is thus disabled; at the same time, the fault state self-locking maintenance switch is turned on because the second control terminal is high, thereby locking the fault pin to a low level.

2. The compressor inverter overcurrent protection circuit according to claim 1, characterized in that, The overcurrent protection circuit also includes: The system restart control switch has a third control terminal, a third collection terminal, and a third transmission terminal. The third control terminal is connected to the disable pin of the main control chip, the third collection terminal is connected to the switch control terminal, and the third transmission terminal is grounded. When the overcurrent protection circuit is activated: the disable pin outputs a high level, the system restart control switch is turned on because the third control terminal is high, pulling the switch control terminal low, so that the rectifier unit enters normal operation; after the rectifier unit is running normally, the disable pin switches to output a low level; at the same time, the voltage comparator outputs a high level, the overcurrent protection control switch is turned on because the third control terminal is high, and the fault state self-locking maintenance switch is turned off because the switch control terminal is low.

3. The compressor inverter overcurrent protection circuit according to claim 2, characterized in that, The overcurrent protection control switch, fault state self-locking maintenance switch, and system restart control switch are all transistors or metal-oxide-semiconductor field-effect transistors.

4. The compressor inverter overcurrent protection circuit according to any one of claims 1 to 3, characterized in that, The rectifier unit includes multiple power switching devices and multiple driver chips; the multiple power switching devices form a three-phase bridge arm topology, with each phase upper bridge arm connected to the positive terminal of the DC bus voltage and each phase lower bridge arm connected to the negative terminal of the DC bus voltage through the sampling resistor; each driver chip is configured to independently drive a single power switching device, or to share the driving of multiple power switching devices in the same bridge arm group.

5. The compressor inverter overcurrent protection circuit according to claim 4, characterized in that, The power switching device can be an insulated gate bipolar transistor or a metal-oxide-semiconductor field-effect transistor.

6. The compressor inverter overcurrent protection circuit according to claim 4, characterized in that, A capacitor is provided between the positive terminal of the DC bus voltage and the negative terminal of the DC bus voltage.

7. The compressor inverter overcurrent protection circuit according to claim 4, characterized in that, The driver chip includes a disable / enable pin, and the disable / enable pins of each driver chip are connected together. Multiple driver chips are controlled by the same control signal.

8. The compressor inverter overcurrent protection circuit according to any one of claims 5 to 7, characterized in that, Each of the power switching devices is connected in anti-parallel to a diode.

9. A compressor inverter overcurrent protection circuit, characterized in that, It includes: The rectifier unit is used to convert DC voltage into three-phase AC frequency converter voltage; It has a switch control terminal for receiving disable / enable signals; A sampling resistor, connected in series with the DC bus, is used to acquire voltage signals in real time. The main control chip includes analog-to-digital conversion pins and fault pins; An overcurrent protection control switch has a first control terminal, a first collecting terminal and a first transmitting terminal, wherein the first collecting terminal is connected to the switch control terminal and the first transmitting terminal is grounded; A fault-state self-locking sustaining switch has a second control terminal, a second collecting terminal, and a second transmitting terminal. The second control terminal is connected to the switch control terminal, and the second transmitting terminal is grounded. An operational amplifier includes a first input terminal, a second input terminal, and a first output terminal. The first input terminal and the second input terminal are respectively connected to the two ends of the sampling resistor, and the first output terminal is connected to the analog-to-digital conversion pin. A voltage comparator includes a third input terminal, a fourth input terminal, and a second output terminal. The third input terminal is connected to the first output terminal, and the fourth input terminal is used to acquire a preset voltage threshold. The second output terminal is connected to the first control terminal, the second collection terminal, and the fault pin, respectively. The voltage comparator compares the preset voltage threshold with the voltage signal amplified by the operational amplifier. When the voltage signal amplified by the operational amplifier is greater than the preset voltage threshold, the second output terminal outputs a low level; otherwise, the second output terminal outputs a high level. When the overcurrent protection circuit is in overcurrent protection state: the voltage comparator outputs a low level, the overcurrent protection control switch is disconnected because the first control terminal is low, so that the switch control terminal is set to a high level, and the rectifier unit is thus disabled; at the same time, the fault state self-locking maintenance switch is turned on because the second control terminal is high, thereby locking the fault pin to a low level.

10. An air conditioner, characterized in that, The air conditioner includes a housing, and a compressor and an overcurrent protection circuit as described in any one of claims 1 to 9 are disposed inside the housing; The compressor is connected to the overcurrent protection circuit, which is used to drive or disable the compressor.

Images