DC load fault detection circuit and household electrical appliance having the same

Abstract

The present invention discloses a DC load fault detection circuit and a household electrical appliance device having the same. The DC load fault detection circuit includes: a switch unit disposed in the DC load power supply loop; an overvoltage detection unit for outputting an overvoltage protection signal to the switch unit when detecting that the output voltage of the DC power supply unit is overvoltage; an undervoltage detection unit for outputting an undervoltage protection signal to the switch unit when detecting that the output voltage of the DC power supply unit is undervoltage; an overcurrent detection unit for outputting an overcurrent protection signal to the switch unit when detecting that the load current is overcurrent; the switch unit is used to control the disconnection of the DC load power supply loop according to at least one of the overvoltage protection signal, the undervoltage protection signal and the overcurrent protection signal, and can perform corresponding protection control in time when the load has an abnormal fault, so that neither the load nor the external controller is damaged, greatly reducing the equipment failure rate, reducing the maintenance cost, and improving the user experience.

Description

[0001] This application is a divisional application of the invention patent application with the application date of May 25, 2021, the application number of 202110573376.1, and the invention creation name of "DC Load Fault Detection Circuit and Home Appliance Equipment with the Same". Technical Field

[0002] The present invention relates to the technical field of electrical equipment, and in particular to a DC load fault detection circuit and a home appliance equipment with the DC load fault detection circuit. Background Art

[0003] In home appliance equipment such as air conditioners and fans, there are usually some open-loop controlled DC loads, such as PTC (Positive Temperature Coefficient) heaters, synchronous motors, stepper motors, etc., which can work only by providing a DC power supply. Since these DC loads have no feedback terminals and cannot provide fault signals, once an abnormal fault occurs inside the load, the external controller cannot identify it in time, so that corresponding protection control cannot be carried out in time, resulting in a significant increase in the equipment failure rate, not only increasing the maintenance cost, but also affecting the user experience. Summary of the Invention

[0004] The embodiments of the present application solve the technical problem in the prior art that the fault condition of the DC load cannot be identified in time and corresponding protection cannot be carried out. By detecting the voltage and current of the power supply for the DC load, the load situation can be automatically identified, and corresponding protection control can be carried out in time when an abnormal fault occurs in the load, so that neither the load nor the external controller is damaged, the equipment failure rate is greatly reduced, the maintenance cost is reduced, and the user experience is improved.

[0005] The embodiments of the present application provide a DC load fault detection circuit, including: a switch part, which is arranged in the DC load power supply circuit; an overvoltage detection part, which is used to output an overvoltage protection signal to the switch part when detecting that the output voltage of the DC power supply part is overvoltage; an undervoltage detection part, which is used to output an undervoltage protection signal to the switch part when detecting that the output voltage of the DC power supply part is undervoltage; an overcurrent detection part, which is used to output an overcurrent protection signal to the switch part when detecting that the load current is overcurrent; and the switch part is used to control the disconnection of the DC load power supply circuit according to at least one of the overvoltage protection signal, the undervoltage protection signal and the overcurrent protection signal.

[0006] According to the DC load fault detection circuit provided by the embodiments of the present application, by setting a switch unit in the power supply loop and detecting and judging the voltage of the DC power supply unit and the load current, once overvoltage, undervoltage, or overcurrent occurs, the switch unit is directly triggered to disconnect the power supply loop. Therefore, corresponding protection control can be carried out in a timely manner when the load has an abnormal fault, so that neither the load nor the external controller is damaged, greatly reducing the equipment failure rate, reducing the maintenance cost, and improving the user experience.

[0007] Optionally, according to an embodiment of the present application, the overvoltage detection unit includes: a first comparison voltage providing unit, the first comparison voltage providing unit is connected to the output end of the DC power supply unit, and the first comparison voltage providing unit is used to charge and discharge according to the output voltage of the DC power supply unit to provide a first comparison voltage; a second comparison voltage providing unit, the second comparison voltage providing unit is connected to the output end of the DC power supply unit, and the second comparison voltage providing unit is used to divide the output voltage of the DC power supply unit to provide a second comparison voltage; a first comparison unit, the first comparison unit is used to compare the first comparison voltage with the second comparison voltage to output the overvoltage protection signal when the output voltage of the DC power supply unit instantaneously rises from a preset stable voltage.

[0008] Optionally, according to an embodiment of the present application, the undervoltage detection unit includes: a third comparison voltage providing unit, the third comparison voltage providing unit is connected to the output end of the DC power supply unit, and the third comparison voltage providing unit is used to charge and discharge according to the output voltage of the DC power supply unit to provide a third comparison voltage; a fourth comparison voltage providing unit, the fourth comparison voltage providing unit is connected to the output end of the DC power supply unit, and the fourth comparison voltage providing unit is used to divide the output voltage of the DC power supply unit to provide a fourth comparison voltage; a second comparison unit, the second comparison unit is used to compare the third comparison voltage with the fourth comparison voltage to output the undervoltage protection signal when the output voltage of the DC power supply unit instantaneously drops from a preset stable voltage.

[0009] Optionally, according to an embodiment of the present application, the undervoltage detection unit includes: a third comparison voltage providing unit, the third comparison voltage providing unit is connected to the output end of the DC power supply unit, and the third comparison voltage providing unit is used to charge and discharge according to the output voltage of the DC power supply unit to provide a third comparison voltage; a second comparison unit, the second comparison unit is used to compare the third comparison voltage with the second comparison voltage to output the undervoltage protection signal when the output voltage of the DC power supply unit instantaneously drops from a preset stable voltage.

[0010] Optionally, according to an embodiment of the present application, the overvoltage detection unit includes: a first comparison voltage providing unit configured to charge and discharge according to the output voltage of the DC power supply unit to provide a first comparison voltage; a first comparison unit configured to compare the first comparison voltage with a fourth comparison voltage to output an overvoltage protection signal when the output voltage of the DC power supply unit instantaneously rises from a preset stable voltage.

[0011] Optionally, according to an embodiment of the present application, the first comparison voltage providing unit includes: a first resistor, one end of which is connected to the output terminal of the DC power supply unit; a second resistor, one end of which is connected to the other end of the first resistor and has a first node, and the other end of the second resistor is grounded; a first capacitor, which is connected in parallel with the second resistor.

[0012] Optionally, according to an embodiment of the present application, the second comparison voltage providing unit includes: a third resistor, one end of which is connected to the output terminal of the DC power supply unit; a fourth resistor, one end of which is connected to the other end of the third resistor and has a second node, and the other end of the fourth resistor is grounded.

[0013] Optionally, according to an embodiment of the present application, the first comparison unit includes: a first comparator, the positive input terminal of which is connected to the first node, the negative input terminal of which is connected to the second node, and the output terminal of which is connected to the control terminal of the switch unit; a fifth resistor, one end of which is connected to the output terminal of the first comparator, and the other end of which is connected to the output terminal of the DC power supply unit.

[0014] Optionally, according to an embodiment of the present application, the third comparison voltage providing unit includes: a sixth resistor, one end of which is connected to the output terminal of the DC power supply unit; a seventh resistor, one end of which is connected to the other end of the sixth resistor and has a third node, and the other end of the seventh resistor is grounded; a second capacitor, which is connected in parallel with the seventh resistor.

[0015] Optionally, according to an embodiment of the present application, the fourth comparison voltage providing unit includes: an eighth resistor, one end of which is connected to the output terminal of the DC power supply unit; a ninth resistor, one end of which is connected to the other end of the eighth resistor and has a fourth node, and the other end of the ninth resistor is grounded.

[0016] Optionally, according to an embodiment of the present application, the second comparison unit includes: a second comparator, a positive input terminal of the second comparator is connected to the fourth node, a negative input terminal of the second comparator is connected to the third node, and an output terminal of the second comparator is connected to a control terminal of the switching unit.

[0017] Optionally, according to an embodiment of the present application, the third comparison voltage providing unit includes: a sixth resistor, one end of the sixth resistor is connected to an output terminal of the DC power supply unit; a seventh resistor, one end of the seventh resistor is connected to the other end of the sixth resistor and has a third node, and the other end of the seventh resistor is grounded; a second capacitor, the second capacitor is connected in parallel with the seventh resistor.

[0018] Optionally, according to an embodiment of the present application, the second comparison unit includes: a second comparator, a positive input terminal of the second comparator is connected to an output terminal of the second comparison voltage providing unit, a negative input terminal of the second comparator is connected to the third node, and an output terminal of the second comparator is connected to a control terminal of the switching unit.

[0019] Optionally, according to an embodiment of the present application, the overcurrent detection unit includes: a current detecting resistor, the current detecting resistor is disposed in the DC load power supply loop; a tenth resistor, one end of the tenth resistor is connected to a reference voltage providing terminal of the DC power supply unit; an eleventh resistor, one end of the eleventh resistor is connected to the other end of the tenth resistor and has a fifth node, and the other end of the eleventh resistor is connected to one end of the current detecting resistor and then grounded; a third comparator, a positive input terminal of the third comparator is connected to the fifth node, a negative input terminal of the third comparator is connected to the other end of the current detecting resistor, and an output terminal of the third comparator is connected to a control terminal of the switching unit.

[0020] Optionally, according to an embodiment of the present application, the switching unit includes: a twelfth resistor, one end of the twelfth resistor serves as a control terminal of the switching unit; a thirteenth resistor, one end of the thirteenth resistor is connected to the other end of the twelfth resistor, and the other end of the thirteenth resistor is connected to the other end of the current detecting resistor; a first MOS transistor, a drain of the first MOS transistor is respectively connected to the other end of the thirteenth resistor and the other end of the current detecting resistor, a source of the first MOS transistor is connected to a DC load, and a gate of the first MOS transistor is connected to the other end of the twelfth resistor.

[0021] An embodiment of the present application further provides a household electrical appliance, and the household electrical appliance includes the above-mentioned DC load fault detection circuit.

[0022] According to the household electrical appliance device provided by the embodiments of the present application, through the above-mentioned DC load fault detection circuit, corresponding protection control can be carried out in time when a load fails, so that neither the load nor the external controller is damaged, greatly reducing the equipment failure rate, reducing the maintenance cost, and improving the user experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a block diagram of a DC load fault detection circuit according to an embodiment of the present application;

[0024] Figure 2 It is a circuit diagram of a DC load fault detection circuit according to an embodiment of the present application;

[0025] Figure 3 It is a circuit diagram of a DC load fault detection circuit according to another embodiment of the present application;

[0026] Figure 4 It is a circuit diagram of a DC load fault detection circuit according to still another embodiment of the present application;

[0027] Figure 5 It is a schematic diagram of the protection logic waveform of an overvoltage detection circuit according to an embodiment of the present application;

[0028] Figure 6 It is a schematic diagram of the protection logic waveform of an undervoltage detection circuit according to an embodiment of the present application;

[0029] Figure 7 It is a block diagram of a household electrical appliance device according to an embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] The DC load fault detection circuit and the household electrical appliance device having the same provided by the embodiments of the present application detect the voltage and current of the power supply for the DC load to automatically identify the load condition. Once overvoltage, undervoltage, overcurrent and other conditions occur, the switch part is directly triggered to disconnect the power supply circuit, so that corresponding protection control can be carried out in time when the load has an abnormal fault, so that neither the load nor the external controller is damaged, greatly reducing the equipment failure rate, reducing the maintenance cost, and improving the user experience.

[0031] In order to better understand the above technical solutions, the exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be fully conveyed to those skilled in the art.

[0032] To better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings of the specification and specific embodiments.

[0033] Next, a DC load fault detection circuit and a household appliance device having the same proposed in an embodiment of the present application will be described with reference to the accompanying drawings.

[0034] Embodiment 1:

[0035] As Figure 1 shown, a circuit for detecting a fault in a DC load proposed in an embodiment of the present application includes a switch unit 10, an overvoltage detection unit 20, an undervoltage detection unit 30, and an overcurrent detection unit 40.

[0036] Among them, in the embodiment of the present application, the switch unit 10 can be composed of a controllable switch. Specifically, as Figure 2 or Figure 3 shown, it can be a controllable switch circuit 101; the overvoltage detection unit 20 can be an overvoltage detection circuit 201 composed of electronic components such as resistors, capacitors, and comparators for detecting and comparing whether the supply voltage has an overvoltage. Specifically, refer to Figure 2 or Figure 3 shown; similarly, the undervoltage detection unit 30 can also be an undervoltage detection circuit 301 composed of electronic components such as resistors, capacitors, and comparators for detecting and comparing whether the supply voltage has an undervoltage. Specifically, refer to Figure 2 or Figure 3 shown; the overcurrent detection unit 40 can be an overcurrent detection circuit 401 composed of electronic components such as resistors and comparators for detecting and comparing whether the load current has an overcurrent. Specifically, refer to Figure 2 or Figure 3 shown.

[0037] As Figure 1As shown, the switch unit 10 can be arranged in the power supply circuit of the DC load to control the on / off of the power supply circuit; the overvoltage detection unit 20 is connected to the positive output terminal of the DC power supply unit 50, such as a power module, and is used to detect and compare whether the power supply voltage output by the DC power supply unit 50 is greater than a voltage setting value. When the power supply voltage output by the DC power supply unit 50 is greater than a voltage setting value, it is determined that the power supply voltage has an overvoltage, and an overvoltage protection signal, which can be a high / low level signal, is output and sent to the switch unit 10 to control the switch unit 10 to disconnect, thus disconnecting the power supply circuit and realizing the corresponding protection control; the undervoltage detection unit 30 is connected to the positive output terminal of the DC power supply unit 50, such as a power module, and is used to detect and compare whether the power supply voltage output by the DC power supply unit 50 is less than another voltage setting value. When the power supply voltage output by the DC power supply unit 50 is less than another voltage setting value, it is determined that the power supply voltage has an undervoltage, and an undervoltage protection signal, which can also be a high / low level signal, is output and sent to the switch unit 10 to control the switch unit 10 to disconnect, thus disconnecting the power supply circuit and realizing the corresponding protection control; the overcurrent detection unit 40 is connected to the negative output terminal of the DC power supply unit 50 and is used to detect and compare whether the load current is greater than a current setting value. When the load current is greater than a current setting value, it is determined that the load current has an overcurrent, and an overcurrent protection signal is output to the switch unit 10 to control the switch unit 10 to disconnect, thus disconnecting the power supply circuit and realizing the corresponding protection control.

[0038] Therefore, in the embodiment of the present application, the switch unit 10 can control the disconnection of the power supply circuit of the DC load according to the overvoltage protection signal, or the undervoltage protection signal, or the overcurrent protection signal, so that protection control can be carried out when the load has an abnormal fault. It can be understood that the switch unit 10 can also control the disconnection of the power supply circuit of the DC load when receiving two or three of the overvoltage protection signal, the undervoltage protection signal, and the overcurrent protection signal to realize abnormal protection control.

[0039] In summary, the circuit for fault detection of the DC load proposed in the embodiment of the present application sets a switch unit in the power supply circuit, and automatically identifies the load situation by detecting and comparing the voltage and current of the power supply for the DC load. Once overvoltage, undervoltage, or overcurrent occurs, the switch unit is directly triggered to disconnect the power supply circuit, so that corresponding protection control can be carried out in time when the load fails, preventing both the load and the external controller from being damaged, greatly reducing the equipment failure rate, reducing the maintenance cost, and improving the user experience.

[0040] Embodiment 2:

[0041] In an embodiment of the present application, as Figure 2As shown, the overvoltage detection unit is the overvoltage detection circuit 201, which includes a first comparison voltage providing unit 2011, a second comparison voltage providing unit 2012, and a first comparison unit 2013.

[0042] Among them, the providing unit 2011 for providing the first comparison voltage is connected to the positive output terminal of the DC power supply unit 50, such as the power supply module, and charges and discharges according to the voltage at the positive output terminal of the power supply module, so as to provide the first comparison voltage; the providing unit 2012 for providing the second comparison voltage is connected to the positive output terminal of the DC power supply unit 50, such as the power supply module, and provides the second comparison voltage by dividing the voltage at the positive output terminal of the power supply module; the first comparison unit 2013 is respectively connected to the providing unit 2011 for providing the first comparison voltage and the providing unit 2012 for providing the second comparison voltage. The first comparison unit 2013 is configured to, when the output voltage of the DC power supply unit 50, such as the power supply module, instantaneously rises from a preset stable voltage, for example, rises to be greater than a voltage setting value, compare the first comparison voltage provided by the providing unit 2011 with the second comparison voltage provided by the providing unit 2012. Since the first comparison voltage is obtained by charging and discharging according to the voltage at the positive output terminal of the power supply module, and the second comparison voltage is directly obtained by dividing the voltage at the positive output terminal of the power supply module, the voltage change rate of the second comparison voltage is greater than that of the first comparison voltage. That is, at this time, the second comparison voltage will be greater than the first comparison voltage, and the first comparison unit 2013 will output an overvoltage protection signal. The switching unit 10 is turned off under the trigger of the level signal corresponding to the overvoltage protection signal, disconnecting the power supply circuit to achieve corresponding protection control.

[0043] And, as Figure 2 shown, the undervoltage detection unit is the undervoltage detection circuit 301, and the circuit topology it adopts can be substantially the same as that of the overvoltage detection circuit, including a third comparison voltage providing unit 3011, a fourth comparison voltage providing unit 3012, and a second comparison unit 3013.

[0044] Among them, the providing unit 3011 for providing the third comparison voltage is connected to the positive output terminal of the DC power supply unit 50, such as a power module, and charges and discharges according to the voltage at the positive output terminal of the power module, so as to provide the third comparison voltage; the providing unit 3012 for providing the fourth comparison voltage is connected to the positive output terminal of the DC power supply unit 50, such as a power module, and provides the fourth comparison voltage by dividing the voltage at the positive output terminal of the power module; the second comparison unit 3013 is respectively connected to the providing unit 3011 for providing the third comparison voltage and the providing unit 3012 for providing the fourth comparison voltage. The second comparison unit 3013 is configured to, when the output voltage of the DC power supply unit 50, such as a power module, instantaneously drops from a preset stable voltage, for example, drops to be less than another voltage setting value, compare the third comparison voltage provided by the providing unit 3011 with the fourth comparison voltage provided by the providing unit 3012. Since the third comparison voltage is obtained by charging and discharging according to the voltage at the positive output terminal of the power module, and the fourth comparison voltage is directly obtained by dividing the voltage at the positive output terminal of the power module, the voltage change rate of the fourth comparison voltage is greater than that of the third comparison voltage. That is, at this time, the fourth comparison voltage will be less than the third comparison voltage, and the second comparison unit 3013 will output an undervoltage protection signal. The switching unit 10 is turned off under the trigger of the level signal corresponding to the undervoltage protection signal, disconnecting the power supply circuit to achieve corresponding protection control.

[0045] In another embodiment of the present application, as Figure 3 shown, the overvoltage detection unit is the overvoltage detection circuit 201, which includes a first comparison voltage providing unit 2011, a second comparison voltage providing unit 2012, and a first comparison unit 2013.

[0046] Among them, the providing unit 2011 for providing the first comparison voltage is connected to the positive output terminal of the DC power supply unit 50, such as a power module, and charges and discharges according to the voltage at the positive output terminal of the power module, so as to provide the first comparison voltage; the providing unit 2012 for providing the second comparison voltage is connected to the positive output terminal of the DC power supply unit 50, such as a power module, and provides the second comparison voltage by dividing the voltage at the positive output terminal of the power module; the first comparison unit 2013 is respectively connected to the providing unit 2011 for providing the first comparison voltage and the providing unit 2012 for providing the second comparison voltage. When the output voltage of the DC power supply unit 50, such as a power module, instantaneously rises from a preset stable voltage, for example, rises to be greater than a voltage setting value, the first comparison unit 2013 compares the first comparison voltage provided by the providing unit 2011 with the second comparison voltage provided by the providing unit 2012. Since the first comparison voltage is obtained by charging and discharging according to the voltage at the positive output terminal of the power module, and the second comparison voltage is directly obtained by dividing the voltage at the positive output terminal of the power module, the voltage change rate of the second comparison voltage is greater than that of the first comparison voltage. That is, at this time, the second comparison voltage will be greater than the first comparison voltage, and the first comparison unit 2013 will output an overvoltage protection signal. The switching unit 10 is turned off under the trigger of the level signal corresponding to the overvoltage protection signal, disconnecting the power supply circuit to achieve corresponding protection control.

[0047] And, as Figure 3 shown, the undervoltage detection unit is the undervoltage detection circuit 301, which shares the second comparison voltage providing unit 2012 with the overvoltage detection circuit. Therefore, the undervoltage detection circuit 301 may include a third comparison voltage providing unit 3011 and a second comparison unit 3013.

[0048] Among them, the providing unit 3011 for providing the third comparison voltage is connected to the positive output terminal of the DC power supply unit 50, such as the power supply module, and charges and discharges according to the voltage at the positive output terminal of the power supply module, so as to provide the third comparison voltage. The second comparison unit 3013 is respectively connected to the providing unit 3011 for providing the third comparison voltage and the providing unit 2012 for providing the second comparison voltage. When the output voltage of the DC power supply unit 50, such as the power supply module, instantaneously drops from a preset stable voltage, for example, drops below another voltage setting value, the second comparison unit 3013 compares the third comparison voltage provided by the providing unit 3011 with the second comparison voltage provided by the providing unit 2012. Since the third comparison voltage is obtained by charging and discharging according to the voltage at the positive output terminal of the power supply module, and the second comparison voltage is directly divided from the voltage at the positive output terminal of the power supply module, the voltage change rate of the second comparison voltage is greater than that of the third comparison voltage. That is, at this time, the second comparison voltage will be less than the third comparison voltage, and the second comparison unit 3013 will output an undervoltage protection signal. The switching unit 10 is turned off under the trigger of the level signal corresponding to the undervoltage protection signal, disconnecting the power supply circuit to achieve corresponding protection control.

[0049] Therefore, the DC load fault detection circuit provided by the embodiments of the present application can achieve fast protection against instantaneous overvoltage and instantaneous undervoltage of the DC load without feedback, enabling the DC load to operate within a certain voltage range. Once abnormal conditions such as overvoltage and undervoltage occur, the switching unit is directly triggered to disconnect the power supply circuit, so that corresponding protection control can be carried out in a timely manner when the load has an abnormal fault, preventing both the load and the external controller from being damaged, greatly reducing the equipment failure rate, reducing the maintenance cost, and improving the user experience.

[0050] Embodiment 3:

[0051] Specifically, as Figure 2 shown, in an embodiment of the present application, the first comparison voltage providing unit 2011 includes a first resistor R1, a second resistor R2, and a first capacitor C1. Among them, one end of the first resistor R1 is connected to the positive output terminal of the DC power supply unit 50, such as the power supply module. One end of the second resistor R2 is connected to the other end of the first resistor R1 and has a first node J1. The other end of the second resistor R2 is grounded, and the first capacitor C1 is connected in parallel with the second resistor R2.

[0052] And, as Figure 2 shown, the second comparison voltage providing unit 2012 includes a third resistor R3 and a fourth resistor R4. One end of the third resistor R3 is connected to the positive output terminal of the DC power supply unit 50, such as the power supply module. One end of the fourth resistor R4 is connected to the other end of the third resistor R3 and has a second node J2. The other end of the fourth resistor R4 is grounded.

[0053] AsFigure 2 As shown, the first comparison unit 2013 includes a first comparator Vo1 and a fifth resistor R5. The positive input terminal of the first comparator Vo1 is connected to the first node J1, the negative input terminal of the first comparator Vo1 is connected to the second node J2, the output terminal of the first comparator Vo1 is connected to the control terminal of the switch unit 10, one end of the fifth resistor R5 is connected to the output terminal of the first comparator Vo1, and the other end of the fifth resistor R5 is connected to the positive output terminal of the DC power supply unit 50, such as a power module.

[0054] That is to say, the overvoltage detection circuit 201 is composed of resistors R1, R2, R3, R4, R5 and a capacitor C1 and a comparator Vo1. The positive output voltage Vdc of the power module is divided by the third resistor R3 and the fourth resistor R4 to form a second comparison voltage V2 and is connected to the negative input terminal of the first comparator Vo1. The positive output voltage Vdc of the power module is divided by the first resistor R1 and the second resistor R2, and is charged and discharged through the first capacitor C1, and the output first comparison voltage V1 is connected to the positive input terminal of the first comparator Vo1. The output terminal of the first comparator Vo1 is pulled up to Vdc through the fifth resistor R5. It is set that the first comparison voltage V1 is greater than the second comparison voltage V2. For example, it can be set that when Vdc = 12V, the first comparison voltage V1 = 11V and the second comparison voltage V2 = 10V. Combining Figure 2 and Figure 5 As shown, the process of the overvoltage detection circuit 201 detecting and comparing the output voltage of the power module is as follows:

[0055] (1) When Vdc rises from 0V to 12V, the second comparison voltage V2 quickly reaches 10V, but the first comparison voltage V1 will slowly rise to 11V due to the charging of the first capacitor C1. Before the first comparison voltage V1 slowly rises to 10V, V1 is less than V2, and the first comparator Vo1 outputs a low level L. At this time, the MOS transistor Q1 in the controllable switch circuit 101 is not turned on, the power supply loop is not turned on, and the DC load stops working. After the first comparison voltage V1 slowly rises above 10V, V1 is greater than V2, and the first comparator Vo1 outputs a high level H, which can drive the MOS transistor Q1 in the controllable switch circuit 101 to turn on.

[0056] (2) After Vdc stabilizes at 12V, the second comparison voltage V2 stabilizes at 10V, the first comparison voltage V1 stabilizes at 11V, V1 is greater than V2, and the first comparator Vo1 stably outputs a high level H; if the output terminal voltage of the power supply module has an instantaneous upward fluctuation at this time, due to the capacitor charging of the first capacitor C1, the voltage change rate of the second comparison voltage V2 is greater than that of the first comparison voltage V1, the second comparison voltage V2 will be instantaneously higher than the first comparison voltage V1, and the first comparator Vo1 will promptly output a low level L. At this time, the MOS transistor Q1 in the drive controllable switch circuit 101 is turned off, the power supply loop is disconnected, and the DC load stops working.

[0057] (3) When Vdc starts to drop from 12V to 0V, the second comparison voltage V2 quickly reaches 0V, but the first comparison voltage V1 will slowly drop to 0V due to the discharge of the C1 capacitor; during the dropping process, the first comparison voltage V1 is always higher than the second comparison voltage V2, and the first comparator Vo1 always outputs a high level H. At this time, the drive of Q1 is at a high level, overvoltage detection protection is not performed, and undervoltage detection circuit is used for protection control.

[0058] It can be seen from this that the overvoltage detection circuit 201 is entirely constructed by simple components such as resistors, capacitors, and comparators, controls the MOS transistor Q1 in the controllable switch circuit 101, adopts a pure hardware circuit design, does not require adding an MCU chip and control software, is simple to implement, not only has low cost, but also has reliable control.

[0059] Furthermore, as Figure 2 shown, the third comparison voltage providing unit 3011 includes a sixth resistor R6, a seventh resistor R7, and a second capacitor C2. One end of the sixth resistor R6 is connected to the positive output terminal of the DC power supply unit 50, such as the power supply module. One end of the seventh resistor R7 is connected to the other end of the sixth resistor R6 and has a third node J3. The other end of the seventh resistor R7 is grounded, and the second capacitor C2 is connected in parallel with the seventh resistor R7.

[0060] And, as Figure 2 shown, the fourth comparison voltage providing unit 3012 includes an eighth resistor R8 and a ninth resistor R9. One end of the eighth resistor R8 is connected to the positive output terminal of the DC power supply unit 50, such as the power supply module. One end of the ninth resistor R9 is connected to the other end of the eighth resistor R8 and has a fourth node J4. The other end of the ninth resistor R9 is grounded.

[0061] As Figure 2 shown, the second comparison unit 3013 includes a second comparator Vo2. The positive input terminal of the second comparator Vo2 is connected to the fourth node J4, the negative input terminal of the second comparator Vo2 is connected to the third node J3, and the output terminal of the second comparator Vo2 is connected to the control terminal of the switch unit.

[0062] That is to say, the undervoltage detection circuit 301 is composed of resistors R6, R7, R8, R9, capacitors C2, and comparator Vo2. The positive output voltage Vdc of the power supply module is divided by the third resistor R8 and the fourth resistor R9 to form a fourth comparison voltage V4, which is connected to the positive input terminal of the second comparator Vo2. The positive output voltage Vdc of the power supply module is divided by the sixth resistor R6 and the seventh resistor R7, and is charged and discharged through the second capacitor C2, and the output third comparison voltage V3 is connected to the negative input terminal of the second comparator Vo2. The output terminal of the second comparator Vo2 is pulled up to Vdc through the fifth resistor R5, and it is set that the third comparison voltage V3 is less than the fourth comparison voltage V4. For example, when Vdc = 12V, the third comparison voltage V3 = 10V and the fourth comparison voltage V4 = 11V can be set. Combined with Figure 2 and Figure 6 As shown, the process of the undervoltage detection circuit 301 detecting and comparing the output voltage of the power supply module is as follows:

[0063] (1) When Vdc rises from 0V to 12V, the fourth comparison voltage V4 quickly reaches 11V, but the third comparison voltage V3 will slowly rise to 10V due to the charging of the second capacitor C2; during the rising process, the fourth comparison voltage V4 is always greater than the third comparison voltage V3, and the second comparator Vo2 always outputs a high level H, and at this time Q1 is driven to a high level;

[0064] (2) After Vdc stabilizes at 12V, the fourth comparison voltage V4 stabilizes at 11V, the third comparison voltage V3 stabilizes at 10V, V4 is greater than V3, and the second comparator Vo2 stably outputs a high level H; if the output voltage of the power supply module has an instantaneous downward fluctuation at this time, due to the capacitor charging of the second capacitor C2, the voltage change rate of the fourth comparison voltage V4 is greater than the voltage change rate of the third comparison voltage V3, and the fourth comparison voltage V4 will be instantaneously lower than the third comparison voltage V3, and the second comparator Vo2 will promptly output a low level L. At this time, the MOS transistor Q1 in the controllable switch circuit 101 is turned off, the power supply circuit is disconnected, and the DC load stops working.

[0065] (3) When Vdc drops from 12V to 0V, the fourth comparison voltage V4 quickly reaches 0V, but the third comparison voltage V3 will slowly drop to 0V due to the discharge of the C2 capacitor; before the fourth comparison voltage V4 drops to 10V, the second comparator Vo2 outputs a high level H, and after the fourth comparison voltage V4 drops to less than 10V, the second comparator Vo2 outputs a low level L. At this time, the MOS transistor Q1 in the controllable switch circuit 101 is turned off, the power supply circuit is disconnected, and the DC load stops working.

[0066] It can be seen that the undervoltage detection circuit 301 is also entirely composed of simple components such as resistors, capacitors, and comparators, controls the MOS transistor Q1 in the controllable switch circuit 101, adopts a pure hardware circuit design, does not require adding an MCU chip and control software, is simple to implement, not only has low cost but also reliable control.

[0067] Specifically, in another embodiment of the present application, as Figure 3 shown, the circuit topology of the overvoltage detection circuit 201 is the same as that of the embodiment shown in Figure 2 and will not be elaborated here. The undervoltage detection circuit 301 can share the second comparison voltage providing unit 2012 with the overvoltage detection circuit 201. In this way, the voltage of the fourth comparison voltage V4 can be set to the voltage of the second comparison voltage V2. At this time, the voltage division circuit composed of the resistors R8 and R9 can be omitted. Connect the negative input terminal of the first comparator Vo1 and the positive input terminal of the second comparator Vo2 together, and set the first comparison voltage V1 to be greater than the second comparison voltage V2, and the second comparison voltage V2 to be greater than the third comparison voltage V3. Among them, the control logic is the same as that described in the above embodiment. The waveform of the level change output by the comparator can be seen in Figure 5 and Figure 6 shown.

[0068] Among them, it can be set that when Vdc = 12V, the first comparison voltage V1 = 11V and the second comparison voltage V2 = 10V. Combining Figure 3 and Figure 5 shown, the process of the overvoltage detection circuit 201 detecting and comparing the output voltage of the power supply module is as follows:

[0069] (1) When Vdc rises from 0V to 12V, the second comparison voltage V2 quickly reaches 10V, but the first comparison voltage V1 will slowly rise to 11V due to the charging of the first capacitor C1; before the first comparison voltage V1 slowly rises to 10V, V1 is less than V2, and the first comparator Vo1 outputs a low level L. At this time, the MOS transistor Q1 in the controllable switch circuit 101 is not turned on, the power supply loop is not turned on, and the DC load stops working; after the first comparison voltage V1 slowly rises above 10V, V1 is greater than V2, and the first comparator Vo1 outputs a high level H, which can drive the MOS transistor Q1 in the controllable switch circuit 101 to turn on.

[0070] (2) After Vdc stabilizes at 12V, the second comparison voltage V2 stabilizes at 10V, the first comparison voltage V1 stabilizes at 11V, V1 is greater than V2, and the first comparator Vo1 stably outputs a high level H; if the output voltage of the power supply module has an instantaneous upward fluctuation at this time, due to the charging of the first capacitor C1, the voltage change rate of the second comparison voltage V2 is greater than that of the first comparison voltage V1, the second comparison voltage V2 will be instantaneously higher than the first comparison voltage V1, and the first comparator Vo1 will promptly output a low level L. At this time, the MOS transistor Q1 in the drive controllable switch circuit 101 is turned off, the power supply loop is disconnected, and the DC load stops working.

[0071] (3) When Vdc starts to drop from 12V to 0V, the second comparison voltage V2 quickly reaches 0V, but the first comparison voltage V1 will slowly drop to 0V due to the discharge of the C1 capacitor; during the dropping process, the first comparison voltage V1 is always higher than the second comparison voltage V2, and the first comparator Vo1 always outputs a high level H. At this time, the drive of Q1 is at a high level, and overvoltage detection protection is not performed. The undervoltage detection circuit performs protection control.

[0072] Optionally, as shown in Figure 3 The third comparison voltage providing unit 3011 includes a sixth resistor R6, a seventh resistor R7, and a second capacitor C2. Among them, one end of the sixth resistor R6 is connected to the positive output terminal of the DC power supply unit 50, such as the power supply module. One end of the seventh resistor R7 is connected to the other end of the sixth resistor R6 and has a third node J3. The other end of the seventh resistor R7 is grounded, and the second capacitor C2 is connected in parallel with the seventh resistor R7.

[0073] Moreover, the second comparison unit 3013 includes a second comparator Vo2. The positive input terminal of the second comparator Vo2 is connected to the negative input terminal of the first comparator Vo1, that is, the output terminal of the second comparison voltage providing unit. The negative input terminal of the second comparator Vo2 is connected to the third node J3, and the output terminal of the second comparator Vo2 is connected to the control terminal of the switch unit.

[0074] Specifically, it can be set that when Vdc = 12V, the second comparison voltage V2 = 11V, and the third comparison voltage V3 = 10V. Combining Figure 3 and Figure 6 As shown, the undervoltage detection circuit 301 detects and compares the output voltage of the power supply module as follows:

[0075] (1) When Vdc rises from 0V to 12V, the second comparison voltage V2 quickly reaches 11V, but the third comparison voltage V3 will slowly rise to 10V due to the charging of the second capacitor C2; during the rising process, the second comparison voltage V2 is always greater than the third comparison voltage V3, and the second comparator Vo2 always outputs a high level H. At this time, the drive of Q1 is at a high level;

[0076] (2) When Vdc is stabilized at 12V, the second comparison voltage V2 is stabilized at 11V, the third comparison voltage V3 is stabilized at 10V, V2 is greater than V3, and the second comparator Vo2 stably outputs a high level H; if the output terminal voltage of the power supply module has an instantaneous downward fluctuation at this time, due to the charging of the second capacitor C2, the voltage change rate of the second comparison voltage V2 is greater than that of the third comparison voltage V3, and the second comparison voltage V2 will be instantaneously lower than the third comparison voltage V3. The second comparator Vo2 will promptly output a low level L. At this time, the MOS transistor Q1 in the driving controllable switch circuit 101 is turned off, the power supply loop is disconnected, and the DC load stops working.

[0077] (3) When Vdc starts to drop from 12V to 0V, the second comparison voltage V2 quickly reaches 0V, but the third comparison voltage V3 will slowly drop to 0V due to the discharge of the C2 capacitor; before the second comparison voltage V2 drops to 10V, the second comparator Vo2 outputs a high level H. After the second comparison voltage V2 drops to less than 10V, the second comparator Vo2 outputs a low level L. At this time, the MOS transistor Q1 in the driving controllable switch circuit 101 is turned off, the power supply loop is disconnected, and the DC load stops working.

[0078] Similarly, the undervoltage detection circuit 301 is also entirely constructed by simple components such as resistors, capacitors, and comparators, controls the MOS transistor Q1 in the controllable switch circuit 101, adopts a pure hardware circuit design, does not require adding an MCU chip and control software, is simple to implement, not only has a low cost but also has reliable control.

[0079] Embodiment 4:

[0080] In addition, in another embodiment of the present application, as Figure 4 shown, the first comparison unit 2013 in the overvoltage detection circuit 201 outputs a circuit signal by comparing the values of the first comparison voltage V1 and the fourth comparison voltage V4. The circuit topology of the undervoltage detection circuit 301 is the same as that of the embodiment shown in Figure 2 and will not be elaborated here. The overvoltage detection circuit 201 can share the fourth comparison voltage providing unit 3012 with the undervoltage detection circuit 301. In this way, the voltage of the second comparison voltage V2 can be set to the voltage of the fourth comparison voltage V4. At this time, the voltage dividing circuit composed of the resistors R3 and R4 can be omitted, the negative input terminal of the first comparator Vo1 is connected to the positive input terminal of the second comparator Vo2, and the first comparison voltage V1 is set to be greater than the fourth comparison voltage V4, and the fourth comparison voltage V4 is greater than the third comparison voltage V3. Among them, the control logic is the same as that described in the above embodiment, and the waveform of the level change output by the comparator can be referred to as shown in Figure 5 and Figure 6 shown.

[0081] Among them, it can be set that when Vdc = 12V, the first comparison voltage V1 = 11V and the fourth comparison voltage V4 = 10V. Combining Figure 4 and Figure 5 As shown, the overvoltage detection circuit 201 detects and compares the output voltage of the power supply module as follows:

[0082] (1) When Vdc rises from 0V to 12V, the fourth comparison voltage V4 quickly reaches 10V, but the first comparison voltage V1 will slowly rise to 11V due to the charging of the first capacitor C1; before the first comparison voltage V1 slowly rises to 10V, V1 is less than V4, and the first comparator Vo1 outputs a low level L. At this time, the MOS transistor Q1 in the controllable switch circuit 101 is not turned on, the power supply loop is not turned on, and the DC load stops working; after the first comparison voltage V1 slowly rises above 10V, V1 is greater than V4, and the first comparator Vo1 outputs a high level H, which can drive the MOS transistor Q1 in the controllable switch circuit 101 to turn on.

[0083] (2) After Vdc stabilizes at 12V, the fourth comparison voltage V4 stabilizes at 10V, the first comparison voltage V1 stabilizes at 11V, V1 is greater than V4, and the first comparator Vo1 stably outputs a high level H; if the output voltage of the power supply module has an instantaneous upward fluctuation at this time, due to the capacitor charging of the first capacitor C1, the voltage change rate of the fourth comparison voltage V4 is greater than the voltage change rate of the first comparison voltage V1, and the fourth comparison voltage V4 will be instantaneously higher than the first comparison voltage V1. The first comparator Vo1 will promptly output a low level L. At this time, the MOS transistor Q1 in the controllable switch circuit 101 is turned off, the power supply loop is disconnected, and the DC load stops working.

[0084] (3) When Vdc drops from 12V to 0V, the fourth comparison voltage V4 quickly reaches 0V, but the first comparison voltage V1 will slowly drop to 0V due to the discharge of the C1 capacitor; during the dropping process, the first comparison voltage V1 is always higher than the fourth comparison voltage V4, and the first comparator Vo1 always outputs a high level H. At this time, the drive of Q1 is at a high level, and overvoltage detection protection is not performed. The undervoltage detection circuit performs protection control.

[0085] Optionally, as shown in Figure 4 , the third comparison voltage providing unit 3011 includes a sixth resistor R6, a seventh resistor R7, and a second capacitor C2. Among them, one end of the sixth resistor R6 is connected to the positive output terminal of the DC power supply unit 50, such as the power supply module. One end of the seventh resistor R7 is connected to the other end of the sixth resistor R6 and has a third node J3. The other end of the seventh resistor R7 is grounded, and the second capacitor C2 is connected in parallel with the seventh resistor R7.

[0086] The fourth comparison voltage providing unit 3012 includes an eighth resistor R8 and a ninth resistor R9. One end of the eighth resistor R8 is connected to the positive output terminal of the DC power supply unit 50, such as the power supply module. One end of the ninth resistor R9 is connected to the other end of the eighth resistor R8 and has a fourth node J4, and the other end of the ninth resistor R9 is grounded.

[0087] Specifically, it can be set that when Vdc = 12V, the fourth comparison voltage V4 = 11V and the third comparison voltage V3 = 10V. Combining Figure 3 and Figure 6 As shown, the undervoltage detection circuit 301 detects and compares the output voltage of the power supply module as follows:

[0088] (1) When Vdc rises from 0V to 12V, the fourth comparison voltage V4 quickly reaches 11V, but the third comparison voltage V3 will slowly rise to 10V due to the charging of the second capacitor C2; during the rising process, the fourth comparison voltage V4 is always greater than the third comparison voltage V3, and the second comparator Vo2 always outputs a high level H. At this time, Q1 is driven to a high level;

[0089] (2) After Vdc stabilizes at 12V, the fourth comparison voltage V4 stabilizes at 11V, the third comparison voltage V3 stabilizes at 10V, V4 is greater than V3, and the second comparator Vo2 stably outputs a high level H; if the output terminal voltage of the power supply module has an instantaneous downward fluctuation at this time, due to the charging of the second capacitor C2, the voltage change rate of the fourth comparison voltage V4 is greater than the voltage change rate of the third comparison voltage V3, and the fourth comparison voltage V4 will be instantaneously lower than the third comparison voltage V3. The second comparator Vo2 will promptly output a low level L. At this time, the MOS transistor Q1 in the controllable switch circuit 101 is turned off, disconnecting the power supply loop, and the DC load stops working.

[0090] (3) When Vdc drops from 12V to 0V, the fourth comparison voltage V4 quickly reaches 0V, but the third comparison voltage V3 will slowly drop to 0V due to the discharging of the C2 capacitor; before the fourth comparison voltage V4 drops to 10V, the second comparator Vo2 outputs a high level H. After the fourth comparison voltage V4 drops to less than 10V, the second comparator Vo2 outputs a low level L. At this time, the MOS transistor Q1 in the controllable switch circuit 101 is turned off, disconnecting the power supply loop, and the DC load stops working.

[0091] Similarly, the undervoltage detection circuit 301 is also entirely constructed by simple components such as resistors, capacitors, and comparators, controls the MOS transistor Q1 in the controllable switch circuit 101, adopts a pure hardware circuit design, does not require adding an MCU chip and control software, is simple to implement, not only has a low cost, but also has reliable control.

[0092] Optionally, in an embodiment of the present application, as Figure 2 , Figure 3 or Figure 4 shown, the overcurrent detection unit is an overcurrent detection circuit 401, which includes a current detection resistor Rsh, a tenth resistor R10, an eleventh resistor R11, and a third comparator Vo3.

[0093] Among them, the current detection resistor Rsh is arranged in the power supply circuit of the DC load, that is, one end of the current detection resistor Rsh is connected to the negative terminal of the DC power supply unit 50, such as the power supply module, and then grounded, and the other end of the current detection resistor Rsh is connected to the controllable switch circuit 101. One end of the tenth resistor R10 is connected to the reference voltage providing end Vcc of the DC power supply unit 50, such as the power supply module. One end of the eleventh resistor R11 is connected to the other end of the tenth resistor R10 and has a fifth node J5. The other end of the eleventh resistor R11 is connected to one end of the current detection resistor Rsh and then grounded. The positive input terminal of the third comparator Vo3 is connected to the fifth node J5, the negative input terminal of the third comparator Vo3 is connected to the other end of the current detection resistor Rsh, and the output terminal of the third comparator Vo3 is connected to the control terminal of the switch unit, that is, the controllable switch circuit 101.

[0094] As Figure 2 , Figure 3 or Figure 4 shown, the overcurrent detection circuit 401 is composed of resistors R10, R11, Rsh, and a comparator Vo3. The reference power supply Vcc provided by the power supply module is divided by the tenth resistor R10 and the eleventh resistor R11 into a reference voltage Vref and connected to the positive input terminal of the third comparator Vo3. The sampling voltage Vin formed by the load current I flowing through the current detection resistor Rsh is connected to the negative input terminal of the third comparator Vo3. The output terminal of the third comparator Vo3 is connected to the fifth resistor R5 and pulled up to Vdc. In this way, when the load current I exceeds the overcurrent protection setting value, Vin is greater than Vref, and the comparator Vo3 outputs a low level L. At this time, the MOS transistor Q1 in the controllable switch circuit 101 is turned off, the power supply circuit is disconnected, and the DC load stops working.

[0095] It can be seen that the overcurrent detection circuit 401 is all built by simple components such as resistors and comparators, can control the MOS transistor Q1 in the controllable switch circuit 101, adopts a pure hardware circuit design, does not require adding an MCU chip and control software, is simple to implement, not only has a low cost, but also has reliable control.

[0096] In an embodiment of the present application, as Figure 2 , Figure 3 or Figure 4As shown, the switch section is a controllable switch circuit 101, which includes a twelfth resistor R12, a thirteenth resistor R13, and a first MOS transistor Q1. One end of the twelfth resistor R12 serves as the control end of the switch section. One end of the thirteenth resistor R13 is connected to the other end of the twelfth resistor R12. The other end of the thirteenth resistor R13 is connected to the other end of the current detection resistor Rsh. The drain of the first MOS transistor Q1 is respectively connected to the other end of the thirteenth resistor R13 and the other end of the current detection resistor Rsh. The source of the first MOS transistor Q1 is connected to the DC load, and the gate of the first MOS transistor Q1 is connected to the other end of the twelfth resistor R12.

[0097] It can be seen that the controllable switch circuit 101 is composed of resistors R12, R13, and the MOS transistor Q1. When the outputs of the first comparator Vo1, the second comparator Vo2, and the third comparator Vo3 are all high level H, the first MOS transistor Q1 conducts, the power supply circuit of the DC load is connected, and the DC load works normally. When any one of the outputs of the first comparator Vo1, the second comparator Vo2, and the third comparator Vo3 is low level L, the first MOS transistor Q1 will turn off, disconnect the power supply circuit of the DC load, and stop the DC load from working, achieving protection control.

[0098] It can be understood that in the embodiments of the present application, the first MOS transistor Q1 that functions as a switching device in the controllable switch circuit 101 is not limited to a MOS transistor, and can also be other power transistors, such as IGBTs, etc.

[0099] Specifically, the switching relationship between the outputs of the overvoltage detection section 20, the undervoltage detection section 30, and the overcurrent detection section 40 and the switch section 10, that is, the driving relationship between the outputs of the first comparator Vo1, the second comparator Vo2, and the third comparator Vo3 and the first MOS transistor Q1 is shown in Table 1 below:

[0100] Table 1

[0101]

[0102] Among them, it can be obtained from Table 1 above that as long as any one of the overvoltage detection section 20, the undervoltage detection section 30, and the overcurrent detection section 40 outputs a protection signal, the switch section 10 disconnects, disconnects the power supply circuit of the DC load, and realizes the corresponding protection control. Therefore, the switch section 10 controls the disconnection of the power supply circuit of the DC load according to at least one of the overvoltage protection signal (such as low level), the undervoltage protection signal (such as low level), and the overcurrent protection signal (such as low level), that is, through a combined circuit of instantaneous overvoltage protection, instantaneous undervoltage protection, and instantaneous overcurrent protection, any one of the circuits triggering protection can disconnect the power supply circuit of the DC load and cut off the power supply to achieve timely and effective protection.

[0103] It can be understood that, in the embodiments of the present application, the instantaneous overvoltage protection and the instantaneous undervoltage protection are set by combining resistors and capacitors, and different protection values and protection times can be set, and specific calibration can be performed according to actual situations.

[0104] In summary, the DC load fault detection circuit according to the embodiments of the present application can implement overvoltage detection, undervoltage detection, and overcurrent detection through a pure hardware circuit when there is no feedback from the DC load, achieving rapid protection against instantaneous overvoltage, instantaneous undervoltage, and instantaneous overcurrent of the DC load, enabling the DC load to operate within a certain power supply voltage range, greatly reducing the failure rate of the device, and adopting a pure hardware circuit design without the need to add an MCU chip and control software, with simple implementation and low cost.

[0105] It should be noted that the DC load fault detection circuit provided by the embodiments of the present application can be applied to household electrical appliances with DC loads such as air conditioners and fans. The DC load can be a PTC heater, a motor, etc., and no specific limitations are made here.

[0106] According to the DC load fault detection circuit provided by the embodiments of the present application, by setting a switch part (such as a controllable switch circuit) in the power supply loop and detecting and judging the voltage and load current of the DC power supply part, once overvoltage, undervoltage, or overcurrent occurs, the switch part is directly triggered to disconnect the power supply loop of the DC load. Therefore, corresponding protection control can be performed in a timely manner when an abnormal fault occurs in the DC load, so that neither the load nor the external controller is damaged, greatly reducing the device failure rate, reducing the maintenance cost, and improving the user experience. Moreover, the entire fault detection circuit is built by simple components such as resistors, capacitors, and comparators, adopting a pure hardware circuit design, without the need to add an MCU chip and control software, with simple implementation, low cost, and reliable control.

[0107] As Figure 7 shown, the embodiments of the present application also provide a household electrical appliance 1, which includes the DC load fault detection circuit 2 described in the above embodiments.

[0108] In the embodiments of the present application, the household electrical appliance can be a household electrical appliance such as an air conditioner or a fan.

[0109] According to the household electrical appliance provided by the embodiments of the present application, through the above DC load fault detection circuit, corresponding protection control can be performed in a timely manner when a fault occurs in the load, so that neither the load nor the external controller is damaged, greatly reducing the device failure rate, reducing the maintenance cost, and improving the user experience.

[0110] Those skilled in the art should understand that the embodiments of the present invention can be provided as methods. Therefore, the present invention can adopt the form of an embodiment of a completely hardware implementation.

[0111] It should be noted that in the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps not listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The present invention can be implemented by means of hardware including several different elements and by means of a suitably programmed computer. In the unit claims listing several devices, several of these devices may be embodied by the same item of hardware. The use of the words first, second, and third, etc. does not denote any order. These words may be interpreted as names.

[0112] Although the preferred embodiments of the present invention have been described, additional changes and modifications can be made by those skilled in the art once they learn of the basic inventive concept. Therefore, the appended claims are intended to be construed to include the preferred embodiments as well as all changes and modifications falling within the scope of the present invention.

[0113] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention.

[0114] Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these changes and modifications.

Claims

1. A DC load fault detection circuit, characterized in that, Comprising: A switch unit, provided in the DC load power supply circuit; An overvoltage detection unit, the overvoltage detection unit includes a first comparison voltage providing unit for providing a first comparison voltage, a second comparison voltage providing unit for providing a second comparison voltage, and a first comparison unit. The first comparison voltage providing unit includes a first resistor, a second resistor, and a first capacitor. One end of the first resistor is connected to the output end of the DC power supply unit. One end of the second resistor is connected to the other end of the first resistor and has a first node. The other end of the second resistor is grounded. The first capacitor is connected in parallel with the second resistor; The second comparison voltage providing unit includes a third resistor and a fourth resistor. One end of the third resistor is connected to the output end of the DC power supply unit. One end of the fourth resistor is connected to the other end of the third resistor and has a second node. The other end of the fourth resistor is grounded; The first comparison unit is respectively connected to the first comparison voltage providing unit and the second comparison voltage providing unit; The overvoltage detection unit is used to detect the output voltage of the DC power supply unit, and output an overvoltage protection signal to the switch unit when detecting that the output voltage of the DC power supply unit has an overvoltage; An undervoltage detection unit, the undervoltage detection unit includes a sixth resistor, a seventh resistor, and a second capacitor. One end of the sixth resistor is connected to the output end of the DC power supply unit. One end of the seventh resistor is connected to the other end of the sixth resistor and has a third node. The other end of the seventh resistor is grounded. The second capacitor is connected in parallel with the seventh resistor. The undervoltage detection unit is used to detect the output voltage of the DC power supply unit, and output an undervoltage protection signal to the switch unit when detecting that the output voltage of the DC power supply unit has an undervoltage; An overcurrent detection unit, used to output an overcurrent protection signal to the switch unit when detecting that the load current has an overcurrent; The switch unit is used to control the disconnection of the DC load power supply circuit according to at least one of the overvoltage protection signal, the undervoltage protection signal, and the overcurrent protection signal; The overcurrent detection unit includes: A current detection resistor, the current detection resistor is provided in the DC load power supply circuit; A tenth resistor, one end of the tenth resistor is connected to the reference voltage providing end of the DC power supply unit; An eleventh resistor, one end of the eleventh resistor is connected to the other end of the tenth resistor and has a fifth node. The other end of the eleventh resistor is connected to one end of the current detection resistor and then grounded; A third comparator, the positive input terminal of the third comparator is connected to the fifth node, the negative input terminal of the third comparator is connected to the other end of the current detection resistor, and the output terminal of the third comparator is connected to the control terminal of the switch unit.

2. The DC load fault detection circuit according to claim 1, characterized in that, The overvoltage detection unit is further used to compare the output voltage of the DC power supply unit based on the second comparison voltage to determine whether the output voltage of the DC power supply unit has an overvoltage.

3. The DC load fault detection circuit according to claim 2, wherein The overvoltage detection unit further includes: A first comparator, wherein the positive input terminal of the first comparator is connected to the first node, the negative input terminal of the first comparator receives the second comparison voltage, and the output terminal of the first comparator is connected to the control terminal of the switching unit; A fifth resistor, one end of the fifth resistor is connected to the output terminal of the first comparator, and the other end of the fifth resistor is connected to the output terminal of the DC power supply unit.

4. The DC load fault detection circuit according to claim 2, wherein The undervoltage detection unit is further configured to compare the output voltage of the DC power supply unit based on the fourth comparison voltage to determine whether the output voltage of the DC power supply unit is undervoltage.

5. The DC load fault detection circuit according to claim 4, characterized in that, The undervoltage detection unit further includes: A second comparator, the positive input terminal of the second comparator receives the fourth comparison voltage, the negative input terminal of the second comparator is connected to the third node, and the output terminal of the second comparator is connected to the control terminal of the switching unit.

6. The DC load fault detection circuit according to claim 4, wherein The second comparison voltage and the fourth comparison voltage are respectively obtained by voltage division according to the output voltage of the DC power supply unit.

7. The DC load fault detection circuit according to claim 6, wherein, The second comparison voltage and the fourth comparison voltage are the same.

8. The DC load fault detection circuit according to claim 1, characterized in that, The switching unit includes: A twelfth resistor, one end of the twelfth resistor serves as the control terminal of the switching unit; A thirteenth resistor, one end of the thirteenth resistor is connected to the other end of the twelfth resistor, and the other end of the thirteenth resistor is connected to the other end of the current detection resistor; A first MOS transistor, the drain of the first MOS transistor is respectively connected to the other end of the thirteenth resistor and the other end of the current detection resistor, the source of the first MOS transistor is connected to a DC load, and the gate of the first MOS transistor is connected to the other end of the twelfth resistor.

9. A household electrical appliance, characterized in that, Comprising the DC load fault detection circuit according to any one of claims 1-8.

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