Detection circuit, protection circuit, motor drive circuit, circuit board and air conditioner

Abstract

This invention discloses a detection circuit, a protection circuit, a motor drive circuit, a circuit board, and an air conditioner. The detection circuit uses a first diode and a second diode with their anodes connected to each other. The sampling signal input terminal is connected to the cathode of the first diode, and the detection module is connected to the cathode of the second diode. The first diode and the second diode can produce a mirror effect, so that the voltage value of the target voltage signal input from the sampling signal input terminal is consistent with the voltage value input to the detection module. This avoids the voltage drop of the diode from affecting the voltage value input to the detection module, thereby improving the accuracy of overcurrent detection.

Description

Technical Field

[0001] This invention relates to the field of detection technology, and in particular to a detection circuit, a protection circuit, a motor drive circuit, a circuit board, and an air conditioner. Background Technology

[0002] Due to natural phenomena such as lightning, circuit component failures, etc., overcurrent may occur in the working circuit. To improve the stability of the working circuit, a detection circuit is usually set in the working circuit. When the detection circuit detects an abnormal current in the working circuit, it will generate an overcurrent signal, which will facilitate subsequent overcurrent protection operations for the working circuit.

[0003] In existing detection circuits, diodes are generally used as isolation devices at the sampling signal input. However, since diodes have a certain voltage drop, and the voltage drop of diodes is easily affected by their own parameters, temperature and other factors, the accuracy of overcurrent detection in the detection circuit is reduced, which is not conducive to subsequent overcurrent protection operations. Summary of the Invention

[0004] The following is an overview of the subject matter described in detail herein. This overview is not intended to limit the scope of the claims.

[0005] This invention provides a detection circuit, a protection circuit, a motor drive circuit, a circuit board, and an air conditioner, which can improve the accuracy of overcurrent detection.

[0006] In a first aspect, embodiments of the present invention provide a detection circuit, comprising:

[0007] A sampling module is used to sample a target voltage signal. The sampling module includes a sampling signal input terminal, a diode assembly, a resistor device, and a power supply terminal. The diode assembly includes a first diode and a second diode whose anodes are connected to each other. The cathode of the first diode is connected to the sampling signal input terminal. The power supply terminal is used to connect to a power source. The power supply terminal is connected to the anode of the first diode through the resistor device.

[0008] The detection module is used to detect the overcurrent state at the sampling signal input terminal based on the voltage value of the target voltage signal. The detection module is connected to the cathode of the second diode.

[0009] The detection circuit provided in this embodiment of the invention has at least the following beneficial effects: by setting a first diode and a second diode with their anodes connected to each other, and connecting the sampling signal input terminal to the cathode of the first diode and the detection module to the cathode of the second diode, the first diode and the second diode can produce a mirror effect, so that the voltage value of the target voltage signal input from the sampling signal input terminal is consistent with the voltage value input to the detection module, avoiding the influence of the diode voltage drop on the voltage value input to the detection module, thereby improving the accuracy of overcurrent detection.

[0010] In some embodiments of the present invention, the sampling signal input terminal includes a first phase input terminal, a second phase input terminal, and a third phase input terminal;

[0011] The number of diode components and resistors are both three. The cathodes of the three first diodes are respectively connected to the first phase input terminal, the second phase input terminal and the third phase input terminal. The cathodes of the three second diodes are all connected to the detection module. The power supply terminal is respectively connected to the anodes of the three first diodes through the three resistors.

[0012] In the above technical solution, the sampling signal input terminal includes a first phase input terminal, a second phase input terminal and a third phase input terminal, so that the detection circuit can detect the overcurrent state of the three phase inputs respectively.

[0013] In some embodiments of the present invention, the cathodes of the three second diodes are interconnected and then connected to the detection module.

[0014] In the above technical solution, the sampling module can sample the maximum voltage value in the three-phase input. Therefore, when the number of detection modules is only one, the overcurrent state of the three-phase input can be detected, which helps to reduce the overall cost of the detection circuit.

[0015] In some embodiments of the present invention, the detection circuit further includes:

[0016] The voltage divider module is used to connect the cathode of the second diode to the detection module.

[0017] In the above technical solution, by setting a voltage divider module, the cathode of the second diode is connected to the detection module through the voltage divider module, so that the voltage signal input to the detection module can be within the acceptable range of the detection module, avoiding the detection module from malfunctioning and improving the stability of the detection circuit.

[0018] In some embodiments of the present invention, the voltage divider module includes a voltage divider input terminal, a first resistor, a second resistor, and a ground terminal connected in series, wherein the ground terminal is used to connect to a reference ground, and the cathode of the second diode is connected to the voltage divider input terminal;

[0019] The detection module includes a detection input terminal, which is connected between the first resistor and the second resistor.

[0020] In the above technical solution, the voltage divider module includes a voltage divider input terminal, a first resistor, a second resistor and a ground terminal connected in series, which has the advantages of simple structure and low cost.

[0021] In some embodiments of the present invention, a filter capacitor is connected in parallel with the second resistor.

[0022] In the above technical solution, by connecting a filter capacitor in parallel with the second resistor, interference in the voltage signal input to the detection module can be filtered out, thereby improving the detection accuracy of the detection module.

[0023] In some embodiments of the present invention, the detection module includes a comparator, the input of which is connected to the cathode of the second diode.

[0024] In the above technical solution, the detection module uses a comparator, which has the advantages of simple structure and low cost. In addition, the comparator has low delay and outputs a simple binary signal, which has the advantage of high detection efficiency.

[0025] Secondly, embodiments of the present invention also provide a protection circuit, including the detection circuit described in the first aspect, and:

[0026] A controller is used to output a control signal based on the overcurrent state at the input of the sampling signal, and the controller is connected to the detection module.

[0027] Therefore, the protection circuit provided in this embodiment of the invention sets up a first diode and a second diode with their anodes connected to each other, and connects the sampling signal input terminal to the cathode of the first diode and the detection module to the cathode of the second diode. The first diode and the second diode can produce a mirror effect, so that the voltage value of the target voltage signal input from the sampling signal input terminal is consistent with the voltage value input to the detection module. This avoids the voltage drop of the diode from affecting the voltage value of the input detection module, thereby improving the accuracy of overcurrent detection.

[0028] Thirdly, embodiments of the present invention also provide a motor drive circuit, including the protection circuit described in the second aspect, and:

[0029] The intelligent power module is used to drive the motor, and the intelligent power module is connected to the sampling signal input terminal and the controller respectively.

[0030] Therefore, the motor drive circuit provided in this embodiment of the invention sets up a first diode and a second diode with their anodes connected to each other, and connects the sampling signal input terminal to the cathode of the first diode and the detection module to the cathode of the second diode. The first diode and the second diode can produce a mirror effect, so that the voltage value of the target voltage signal input from the sampling signal input terminal is consistent with the voltage value input to the detection module. This avoids the voltage drop of the diode from affecting the voltage value of the input detection module, thereby improving the accuracy of overcurrent detection.

[0031] In some embodiments of the present invention

[0032] The intelligent power module includes three parallel bridge arms. Each bridge arm includes a series-connected sampling resistor and two switching devices. Each bridge arm is connected in series with a sampling resistor. The sampling signal input terminal is connected between the switching device and the sampling resistor of at least one bridge arm. Each switching device is connected to the controller.

[0033] Alternatively, the intelligent power module includes three parallel bridge arms, each bridge arm including two switching devices connected in series, each bridge arm being connected in series with the same sampling resistor, the sampling signal input terminal being connected between the switching device and the sampling resistor of the bridge arm, and each switching device being connected to the controller.

[0034] In the above technical solution, the sampling signal input terminal is connected between the switching device and the sampling resistor of the bridge arm. Each switching device is connected to the controller. The target voltage signal of the corresponding bridge arm can be sent to the controller through the sampling signal input terminal. The controller can control the switching device to open or close according to the target voltage signal of the corresponding bridge arm. When the voltage value of the target voltage signal sampled by the sampling signal input terminal is too large, the switching device can be controlled to open to achieve the effect of overcurrent protection.

[0035] Fourthly, embodiments of the present invention also provide a circuit board, including the detection circuit described in the first aspect, or the protection circuit described in the second aspect, or the motor drive circuit described in the third aspect.

[0036] Therefore, the circuit board provided in this embodiment of the invention sets up a first diode and a second diode with their anodes connected to each other, and the sampling signal input terminal is connected to the cathode of the first diode, and the detection module is connected to the cathode of the second diode. The first diode and the second diode can produce a mirror effect, so that the voltage value of the target voltage signal input from the sampling signal input terminal is consistent with the voltage value input to the detection module, avoiding the influence of the diode voltage drop on the voltage value of the input detection module, thereby improving the accuracy of overcurrent detection.

[0037] Fifthly, embodiments of the present invention also provide an air conditioner, including the detection circuit described in the first aspect, or the protection circuit described in the second aspect, or the motor drive circuit described in the third aspect.

[0038] Therefore, the air conditioner provided in this embodiment of the invention sets up a first diode and a second diode with their anodes connected to each other, and connects the sampling signal input terminal to the cathode of the first diode and the detection module to the cathode of the second diode. The first diode and the second diode can produce a mirror effect, so that the voltage value of the target voltage signal input from the sampling signal input terminal is consistent with the voltage value input to the detection module. This avoids the voltage drop of the diode from affecting the voltage value of the input detection module, thereby improving the accuracy of overcurrent detection.

[0039] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the description, claims and drawings. Attached Figure Description

[0040] The accompanying drawings are provided to further understand the technical solutions of the present invention and constitute a part of the specification. They are used together with the embodiments of the present invention to explain the technical solutions of the present invention, and do not constitute a limitation on the technical solutions of the present invention.

[0041] Figure 1 This is a circuit diagram of the detection circuit provided in an embodiment of the present invention;

[0042] Figure 2 This is another circuit schematic diagram of the detection circuit provided in the embodiment of the present invention;

[0043] Figure 3 This is provided by the embodiments of the present invention. Figure 2 The circuit schematic of the detection circuit applied to the intelligent power module;

[0044] Figure 4 This is provided by the embodiments of the present invention. Figure 2 Another circuit schematic diagram when the detection circuit is applied to a smart power module;

[0045] Figure 5 This is provided by the embodiments of the present invention. Figure 1 The circuit schematic of the detection circuit applied to the intelligent power module;

[0046] Figure 6 This is a circuit schematic diagram of a detection circuit including a voltage divider module provided in an embodiment of the present invention when applied to a smart power module;

[0047] Figure 7This is provided by the embodiments of the present invention. Figure 4 Circuit diagram of a voltage divider module with a different structure;

[0048] Figure 8 This is a schematic diagram of the protection circuit provided in an embodiment of the present invention;

[0049] Figure 9 This is a schematic diagram of the motor drive circuit provided in an embodiment of the present invention. Detailed Implementation

[0050] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail 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 invention.

[0051] It should be understood that in the description of the embodiments of the present invention, "multiple" (or "amounts") means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. If "first," "second," etc., are used in the description, they are only for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0052] Overcurrent detection is essential for the normal operation of most circuits. In existing detection circuits, diodes are generally used as isolation devices at the sampling signal input. However, since diodes have a certain voltage drop, and this voltage drop is easily affected by their own parameters, temperature, and other factors, the accuracy of overcurrent detection is reduced, which is detrimental to subsequent overcurrent protection operations.

[0053] Based on this, embodiments of the present invention provide a detection circuit, a protection circuit, a motor drive circuit, a circuit board, and an air conditioner, which can improve the accuracy of overcurrent detection.

[0054] Reference Figure 1 This invention provides a detection circuit, including a sampling module 110 and a detection module 120. The sampling module 110 is used to sample a target voltage signal. The sampling module 110 includes a sampling signal input terminal 111, a diode assembly 130, a resistor, and a power supply terminal 140. The diode assembly 130 includes a first diode D1 and a second diode D2 whose anodes are connected to each other. The cathode of the first diode D1 is connected to the sampling signal input terminal 111. The power supply terminal 140 is used to connect to a power source and is connected to the anode of the first diode D1 through the resistor. Figure 1The medium-resistance device is the first pull-up resistor R4; the detection module 120 is used to detect the overcurrent state of the sampling signal input terminal 111 according to the voltage value of the target voltage signal, and the detection module 120 is connected to the cathode of the second diode D2.

[0055] It can be understood that the sampling signal input terminal 111 is used to connect to the circuit to be tested. The target voltage signal is input from the sampling signal input terminal 111. The target voltage signal is used for the detection module 120 to determine the overcurrent state. By setting the first diode D1 and the second diode D2 with their anodes connected to each other, and the sampling signal input terminal 111 is connected to the cathode of the first diode D1, and the detection module 120 is connected to the cathode of the second diode D2, the first diode D1 and the second diode D2 can produce a mirror effect, so that the voltage value of the target voltage signal input from the sampling signal input terminal 111 is consistent with the voltage value input to the detection module 120. This avoids the voltage drop of the diode from affecting the voltage value input to the detection module 120, thereby improving the accuracy of overcurrent detection.

[0056] Furthermore, since the voltage drop of the diode is avoided from affecting the voltage value of the input detection module 120, the detection circuit provided in this embodiment of the invention can be applied to overcurrent detection of discrete power device circuits, making the scope of application of the detection circuit wider.

[0057] It is understood that the first diode D1 and the second diode D2 can be discrete components or integrated into the same component. This embodiment of the invention does not impose any limitations. Furthermore, the parameters of the first diode D1 and the second diode D2 are the same to ensure the mirroring effect.

[0058] Reference Figures 2 to 3As one application of the detection circuit in this embodiment of the invention, the detection circuit can be used to detect the overcurrent state of a motor drive circuit. The motor drive circuit can be driven by an intelligent power module, which includes three parallel bridge arms. Each bridge arm includes two switching devices connected in series. Each bridge arm is connected in series with a sampling resistor. A sampling signal input terminal 111 is connected between the switching device and the sampling resistor of at least one bridge arm. Each switching device is connected to a controller. Specifically, the three bridge arms include a first bridge arm, a second bridge arm, and a third bridge arm. The first bridge arm includes a first switching device Q1 and a second switching device Q2 connected in series. The second bridge arm includes a third switching device Q3 and a fourth switching device Q4 connected in series. The third bridge arm includes a fifth switching device Q5 and a sixth switching device Q6 connected in series. The first, second, and third bridge arms are respectively connected to a three-phase power supply. The three control signal input terminals of the motor are respectively connected between the two switching devices of each bridge arm. The first bridge arm is connected in series with a first sampling resistor R1, the second bridge arm with a second sampling resistor R2, and the third bridge arm with a third sampling resistor R3.

[0059] Accordingly, the sampling signal input terminal 111 includes a first phase input terminal 210, a second phase input terminal 220, and a third phase input terminal 230. The number of diode components 130 and resistors are three. The cathodes of the three first diodes D1 are respectively connected to the first phase input terminal 210, the second phase input terminal 220, and the third phase input terminal 230. The cathodes of the three second diodes D2 are all connected to the detection module 120. The power supply terminal 140 is respectively connected to the anodes of the three first diodes D1 through three resistors. Based on this, the detection circuit includes three sampling paths. Specifically, the detection circuit is provided with a first sampling branch, a second sampling branch, and a third sampling branch. The first sampling branch includes a first phase input terminal 210, a first diode assembly, a first pull-up resistor R4, and a power supply terminal 140. The second sampling branch includes a second phase input terminal 220, a second diode assembly, a second pull-up resistor R5, and a power supply terminal 140. The third sampling branch includes a third phase input terminal 230, a third diode assembly, a third pull-up resistor R6, and a power supply terminal 140. The first sampling branch is used to acquire the target voltage signal of the first bridge arm. The first phase input terminal 210 is connected between the second switching device Q2 and the first sampling resistor R1. The second phase input terminal 220 is connected between the fourth switching device Q4 and the second sampling resistor R2. The third phase input terminal 230 is connected between the sixth switching device Q6 and the third sampling resistor R3. The first diode assembly, the second diode assembly, and the third diode assembly all include a first diode D1 and a second diode D2. In this circuit, the cathode of the second diode D2 is the sampling output terminal of each sampling branch. The cathodes of the three second diodes D2 are interconnected and then connected to the detection module 120. That is, the cathodes of the second diodes D2 of the first sampling branch, the second sampling branch and the third sampling branch are interconnected. Therefore, the sampling module 110 can sample the maximum voltage of the three-phase input. Thus, when the number of detection modules 120 is one, the overcurrent state of the three-phase input can be detected, which helps to reduce the overall cost of the detection circuit.

[0060] Taking the first sampling branch as an example, the resistance value of the first pull-up resistor R4 can be much larger than the resistance value of the first sampling resistor R1 to ensure the sampling accuracy of the sampling module.

[0061] It should be added that, referring to Figure 4 In other embodiments, the cathodes of the second diodes D2 in the first sampling branch, the second sampling branch, and the third sampling branch may not be connected to each other. That is, the first sampling branch, the second sampling branch, and the third sampling branch are respectively connected to different detection modules 120, so that the overcurrent state of the first bridge arm, the second bridge arm, and the third bridge arm can be detected by different detection modules 120 respectively.

[0062] It is understood that the number of sampling branches can be determined according to the actual circuit under test. This embodiment of the invention does not impose any limitation. For example, only one sampling branch can be used to detect the target voltage signal of each of the three bridge arms.

[0063] Additionally, refer to Figure 5 As another application of the detection circuit in this embodiment of the invention, and Figure 2 The difference in the circuit shown is that the number of sampling resistors has become one, and the number of sampling branches has also become one. Specifically, the first bridge arm, the second bridge arm, and the third bridge arm are all connected in series with the first sampling resistor R1. The sampling signal input terminal 111 is connected between the first bridge arm and the first sampling resistor R1. Similarly, this detection method can also use the diode assembly to generate a mirror effect to improve the accuracy of overcurrent detection.

[0064] The detection circuit provided in this embodiment of the invention also includes a voltage divider module, through which the cathode of the second diode D2 is connected to the detection module 120. By setting the voltage divider module, the cathode of the second diode D2 is connected to the detection module 120, ensuring that the voltage signal input to the detection module 120 is within the acceptable range of the detection module 120, thus preventing the detection module 120 from malfunctioning and improving the stability of the detection circuit.

[0065] Understandable, refer to Figure 6 The voltage divider module includes a voltage divider input terminal 410, a first resistor R7, a second resistor R8, and a ground terminal connected in series. The ground terminal is used to connect to a reference ground. The cathode of the second diode D2 is connected to the voltage divider input terminal 410. The detection module 120 includes a detection input terminal 420 connected between the first resistor R7 and the second resistor R8. The voltage divider module, including the voltage divider input terminal 410, the first resistor R7, the second resistor R8, and the ground terminal connected in series, has the advantages of simple structure and low cost.

[0066] Specifically, the cathode of the second diode D2, the first resistor R7, the second resistor R8, and the reference ground are connected in sequence. Therefore, the voltage input to the detection module 120 is the voltage across the second resistor R8. By changing the resistance values ​​of the first resistor R7 and the second resistor R8, the voltage input to the detection module 120 can be kept within a suitable range. It should be noted that the resistance values ​​of the first resistor R7 and the second resistor R8 can be set according to actual conditions, and this embodiment of the invention does not impose any limitations.

[0067] It is understood that a filter capacitor C1 is connected in parallel with the second resistor R8. By connecting the filter capacitor C1 in parallel with the second resistor R8, interference in the voltage signal input to the detection module 120 can be filtered out, thereby improving the detection accuracy of the detection module 120.

[0068] Understandable, refer to Figure 6 The detection module 120 can use a comparator, which has the advantages of simple structure and low cost. In addition, the comparator has low delay and outputs a simple binary signal, which has the advantage of high detection efficiency.

[0069] Specifically, the detection module 120 includes a comparator, a third resistor R9, a fourth resistor R10, a fifth resistor R11, a sixth resistor R12, a first capacitor C2, and a second capacitor C3. The inverting input terminal of the comparator is the detection input terminal 420. The third resistor R9 and the fourth resistor R10 are connected in series between the power supply and the reference ground. The non-inverting input terminal of the comparator is connected between the third resistor R9 and the fourth resistor R10. The fifth resistor R11 and the first capacitor C2 are connected in series between the power supply and the reference ground. The output terminal of the comparator is connected between the fifth resistor R11 and the first capacitor C2. One end of the sixth resistor R12 is connected to the output terminal of the comparator, and the other end of the sixth resistor R12 is the detection output terminal 430 of the detection module 120, which is used to connect to the controller. The second capacitor C3 is connected to the detection output terminal 430 and the reference ground.

[0070] Understandable, refer to Figure 7 The detection module 120 may also include a comparator, a seventh resistor R13, an eighth resistor R14, a ninth resistor R15, a tenth resistor R16, an eleventh resistor R17, a twelfth resistor R18, a third capacitor C4, a third diode DZ1, and a fourth diode DZ2. The inverting input of the comparator is the detection input 420. The seventh resistor R13 and the eighth resistor R14 are connected in series between the power supply and the reference ground. The non-inverting input of the comparator is connected between the seventh resistor R13 and the eighth resistor R14 through the ninth resistor R15. The output of the comparator is connected through the tenth resistor R16. Connect one end of the eleventh resistor R17. The other end of the eleventh resistor R17 is the detection output terminal 430 of the detection module 120, used to connect to the controller. The non-inverting input terminal of the comparator is connected between the tenth resistor R16 and the eleventh resistor R17 through the twelfth resistor R18. The anode of the third diode DZ1 is connected between the tenth resistor R16 and the eleventh resistor R17. The cathode of the third diode DZ1 is connected to the cathode of the fourth diode DZ2. The anode of the fourth diode DZ2 is connected to the reference ground. The third capacitor C4 is connected to the detection output terminal 430 and the reference ground. The connection of the non-inverting input terminal of the comparator between the tenth resistor R16 and the eleventh resistor R17 through the twelfth resistor R18 creates positive feedback, which improves the anti-interference capability of the detection module 120 and further enhances the accuracy of overcurrent detection in the detection circuit.

[0071] based on Figure 6 The detection circuit shown below will be explained in terms of its working principle according to an embodiment of the present invention.

[0072] The first phase input terminal 210, the second phase input terminal 220, and the third phase input terminal 230 respectively sample the voltage values ​​of the first sampling resistor R1, the second sampling resistor R2, and the third sampling resistor R3. At this time, the cathode of the second diode D2 outputs the maximum voltage V among the first sampling resistor R1, the second sampling resistor R2, and the third sampling resistor R3. max V max After voltage division by the first resistor R7 and the second resistor R8, the voltage value V is obtained. in The input is given to the non-inverting input of the comparator, where V in =(R8 / (R7+R8))*V max The third resistor R9 and the fourth resistor R10 divide the power supply voltage and input it to the non-inverting input of the comparator, serving as the comparison threshold voltage V. erf , with V max When comparing, the voltage V at the inverting input of the comparator... max Greater than the non-inverting input voltage V erf At this point, it is confirmed that one of the first sampling resistor R1, the second sampling resistor R2, and the third sampling resistor R3 has experienced an overcurrent. The comparator outputs a low-level signal to the controller. Upon receiving this low-level signal, the controller can control the switching devices of each bridge arm to disconnect, thereby providing protection. Since the first diode D1 and the second diode D2 can produce a mirror effect, the voltage value of the target voltage signal input from the sampling signal input terminal 111 is consistent with the voltage value of the input detection module 120. This avoids the voltage drop of the diode affecting the voltage value of the inverting input terminal of the input comparator, thereby improving the accuracy of overcurrent detection.

[0073] It is understandable that the comparator's comparison threshold voltage V erf The settings can be adjusted according to actual needs. Specifically, this can be achieved by changing the resistance values ​​of the third resistor R9 and the fourth resistor R10, thereby changing the voltage across the fourth resistor R10, and thus altering the comparator's comparison threshold voltage V. erf Of course, the embodiments of the present invention do not limit the resistance values ​​of the third resistor R9 and the fourth resistor R10.

[0074] Understandable, with Figure 6The circuit shown is an example. With a filter capacitor C1 connected in parallel across the second resistor R8, the first pull-up resistor R4, the second pull-up resistor R5, the third pull-up resistor R6, the first resistor R7, and the second resistor R8 can all be variable resistors. The purpose of this arrangement is to control the filtering time of the voltage signal input to the detection input terminal 420 by changing the resistance values ​​of the first pull-up resistor R4, the second pull-up resistor R5, the third pull-up resistor R6, the first resistor R7, or the second resistor R8. Taking the first sampling branch as an example, the first pull-up resistor R4... Either the first resistor R7 or the second resistor R8 can be a variable resistor. By adjusting the resistance value of either the first pull-up resistor R4, the first resistor R7, or the second resistor R8, the filtering time of the voltage signal from the first sampling branch input to the detection input terminal 420 can be controlled. Specifically, for the first sampling branch, the filtering time T can be calculated as: ((R4+R7) / / R8)*C1, where (R4+R7) / / R8 represents the resistance value of the first pull-up resistor R4 connected in series with the first resistor R7 and then connected in parallel with the second resistor R8.

[0075] Of course, those skilled in the art will understand that the detection input terminal 420 can also be the non-inverting input terminal of the comparator. In this case, the comparison logic between the detection input terminal 420 and the comparison threshold voltage of the comparator can be adjusted accordingly.

[0076] It should be noted that the detection circuit provided in this embodiment of the invention is only exemplarily applied to overcurrent detection in motor drive circuits. In fact, the detection circuit in this embodiment of the invention can also be applied to other circuits.

[0077] Additionally, refer to Figure 8 This invention also provides a protection circuit 800, including the detection circuit and controller 810 described in the above embodiments. The controller 810 outputs a control signal based on the overcurrent state of the sampling signal input terminal 111. The controller 810 is connected to the detection module 120. Therefore, the protection circuit 800 sets a first diode D1 and a second diode D2 with their anodes connected to each other. The sampling signal input terminal 111 is connected to the cathode of the first diode D1, and the detection module 120 is connected to the cathode of the second diode D2. The first diode D1 and the second diode D2 can produce a mirror effect, so that the voltage value of the target voltage signal input from the sampling signal input terminal 111 is consistent with the voltage value input to the detection module 120. This avoids the voltage drop of the diodes affecting the voltage value input to the detection module 120, thereby improving the accuracy of overcurrent detection.

[0078] The controller 810 is connected to the detection output terminal 430 of the detection module 120, as referenced. Figure 6Taking the detection module 120, which includes a comparator, as an example, the controller 810 obtains the level signal output by the comparator and can determine whether an overcurrent phenomenon has occurred in the detected circuit based on the comparator's level signal. If the controller 810 confirms that an overcurrent phenomenon has occurred in the detected circuit, it can perform protective actions on the detected circuit, such as disconnecting the detected circuit. As an example, if the detected circuit is a smart power module, the controller 810 can control the switching devices of the smart power module to turn off to achieve a protection effect.

[0079] It should be noted that the principle of the detection circuit in the protection circuit 800 provided in the embodiments of the present invention has been described in detail above, and will not be repeated here.

[0080] Additionally, refer to Figure 9 This invention also provides a motor drive circuit 900, including the aforementioned protection circuit 800 and an intelligent power module 910 for driving a motor. The intelligent power module 910 is connected to the sampling signal input terminal 111 and the controller 810, respectively. Therefore, the motor drive circuit 900 sets a first diode D1 and a second diode D2 with their anodes connected to each other, and the sampling signal input terminal 111 is connected to the cathode of the first diode D1, and the detection module 120 is connected to the cathode of the second diode D2. The first diode D1 and the second diode D2 can produce a mirror effect, so that the voltage value of the target voltage signal input from the sampling signal input terminal 111 is consistent with the voltage value of the input detection module 120, avoiding the influence of the diode voltage drop on the voltage value of the input detection module 120, thereby improving the accuracy of overcurrent detection.

[0081] Understandable, refer to Figure 6 The intelligent power module 910 includes three parallel bridge arms. Each bridge arm includes two switching devices connected in series. Each bridge arm also has a sampling resistor connected in series. A sampling signal input terminal 111 is connected between the switching device and the sampling resistor in at least one bridge arm. Each switching device is connected to the controller 810. Specifically, the three bridge arms include a first bridge arm, a second bridge arm, and a third bridge arm. The first bridge arm includes a first switching device Q1 and a second switching device Q2 connected in series. The second bridge arm includes a third switching device Q3 and a fourth switching device Q4 connected in series. The third bridge arm includes a fifth switching device Q5 and a sixth switching device Q6 connected in series. The first, second, and third bridge arms are respectively connected to a three-phase power supply. The three control signal input terminals of the motor are respectively connected between the two switching devices in each bridge arm. A first sampling resistor R1 is connected in series in the first bridge arm, a second sampling resistor R2 is connected in series in the second bridge arm, and a third sampling resistor R3 is connected in series in the third bridge arm. It can be understood that the number of sampling signal input terminals 111 can be one, two, or three. Figure 6The following example demonstrates the process using three sampling signal input terminals 111. With one terminal 111, the overcurrent status of one bridge arm can be detected. With two terminals 111, the overcurrent status of two bridge arms can be detected separately. With three terminals 111, the overcurrent status of all three bridge arms can be detected separately. Each sampling signal input terminal 111 is connected between a switching device and a sampling resistor in at least one bridge arm. Each switching device is connected to a controller 810. The target voltage signal of the corresponding bridge arm can be sent to the controller 810 through the sampling signal input terminal 111. The controller 810 can control the switching device to open or close based on the target voltage signal of the corresponding bridge arm. When the voltage value of the target voltage signal sampled by the sampling signal input terminal 111 is too high, the switching device can be opened to achieve overcurrent protection.

[0082] It is understood that the motor drive circuit 900 provided in this embodiment of the invention can also be adopted. Figure 5 The structure shown has been explained previously and will not be repeated here.

[0083] It is understandable that the first switching device Q1, the second switching device Q2, the third switching device Q3, the fourth switching device Q4, the fifth switching device Q5, and the sixth switching device Q6 are discrete power devices, which helps to reduce costs.

[0084] It should be noted that the principle of the detection circuit in the motor drive circuit 900 provided in this embodiment of the invention has been described in detail above, and will not be repeated here.

[0085] In addition, this embodiment of the invention also provides a circuit board including the detection circuit described above, or the protection circuit 800 described above, or the motor drive circuit 900 described above. Therefore, by setting a first diode D1 and a second diode D2 with their anodes connected to each other, and the sampling signal input terminal 111 is connected to the cathode of the first diode D1, and the detection module 120 is connected to the cathode of the second diode D2, the first diode D1 and the second diode D2 can produce a mirror effect, so that the voltage value of the target voltage signal input from the sampling signal input terminal 111 is consistent with the voltage value input to the detection module 120, avoiding the influence of the diode voltage drop on the voltage value of the input detection module 120, thereby improving the accuracy of overcurrent detection.

[0086] In addition, this embodiment of the invention also provides an air conditioner, including the detection circuit described above, or the protection circuit 800 described above, or the motor drive circuit 900 described above. Therefore, the air conditioner, by setting a first diode D1 and a second diode D2 with their anodes connected to each other, and the sampling signal input terminal 111 connected to the cathode of the first diode D1, and the detection module 120 connected to the cathode of the second diode D2, can produce a mirror effect between the first diode D1 and the second diode D2, so that the voltage value of the target voltage signal input from the sampling signal input terminal 111 is consistent with the voltage value input to the detection module 120, thus avoiding the influence of the diode voltage drop on the voltage value of the input detection module 120, thereby improving the accuracy of overcurrent detection.

[0087] It should also be understood that the various implementation methods provided in the embodiments of the present invention can be combined arbitrarily to achieve different technical effects.

[0088] The above provides a detailed description of the preferred embodiments of the present invention. However, the present invention is not limited to the above embodiments. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention. All such equivalent modifications or substitutions are included within the scope defined by the claims of the present invention.

Claims

1. A detection circuit, characterized in that, include: A sampling module is used to sample a target voltage signal. The sampling module includes a sampling signal input terminal, a diode assembly, a first pull-up resistor, and a power supply terminal. The diode assembly includes a first diode and a second diode whose anodes are connected to each other. The cathode of the first diode is connected to the sampling signal input terminal. The power supply terminal is used to connect to a power source. The power supply terminal is connected to the anode of the first diode through the first pull-up resistor. The sampling signal input terminal is grounded through the first sampling resistor. The voltage divider module includes a voltage divider input terminal, a first resistor, a second resistor, and a ground terminal connected in series. The ground terminal is used to connect to a reference ground, and the cathode of the second diode is connected to the voltage divider input terminal. The detection module is used to detect the overcurrent state of the sampling signal input terminal based on the voltage value of the target voltage signal. The detection module includes a detection input terminal, which is connected between the first resistor and the second resistor.

2. The detection circuit according to claim 1, characterized in that: The sampling signal input terminal includes a first phase input terminal, a second phase input terminal, and a third phase input terminal; The number of diode components and the number of first pull-up resistors are both three. The cathodes of the three first diodes are respectively connected to the first phase input terminal, the second phase input terminal and the third phase input terminal. The cathodes of the three second diodes are all connected to the detection module. The power supply terminal is respectively connected to the anodes of the three first diodes through the three first pull-up resistors.

3. The detection circuit according to claim 2, characterized in that: The cathodes of the three second diodes are interconnected and then connected to the detection module.

4. The detection circuit according to claim 1, characterized in that: A filter capacitor is connected in parallel with the second resistor.

5. The detection circuit according to claim 1, characterized in that: The detection module includes a comparator, the input of which is connected to the cathode of the second diode.

6. A protection circuit, characterized in that, Includes the detection circuit according to any one of claims 1 to 5, and: A controller is used to output a control signal based on the overcurrent state at the input of the sampling signal, and the controller is connected to the detection module.

7. A motor drive circuit, characterized in that, Including the protection circuit as described in claim 6, and: The intelligent power module is used to drive the motor, and the intelligent power module is connected to the sampling signal input terminal and the controller respectively.

8. The motor drive circuit according to claim 7, characterized in that: The intelligent power module includes three parallel bridge arms, each bridge arm includes two switching devices connected in series, and each bridge arm is connected in series with a sampling resistor. The sampling signal input terminal is connected between the switching device and the sampling resistor of at least one bridge arm, and each switching device is connected to the controller. Alternatively, the intelligent power module includes three parallel bridge arms, each bridge arm including two switching devices connected in series, each bridge arm being connected in series with the same sampling resistor, the sampling signal input terminal being connected between the switching device and the sampling resistor of the bridge arm, and each switching device being connected to the controller.

9. A circuit board, characterized in that, It includes the detection circuit according to any one of claims 1 to 5, or the protection circuit according to claim 6, or the motor drive circuit according to any one of claims 7 to 8.

10. An air conditioner, characterized in that, It includes the detection circuit according to any one of claims 1 to 5, or the protection circuit according to claim 6, or the motor drive circuit according to any one of claims 7 to 8.

Images