Current sampling circuit, overcurrent protection device, intelligent power module and household appliances

Abstract

The present invention discloses a current sampling circuit, an overcurrent protection device, an intelligent power module and a household appliance. The circuit includes: a detection unit, a mirror unit, a voltage division unit, a comparison unit and a sampling unit, wherein the detection unit is suitable for detecting a target current to generate a detection voltage; the mirror unit is suitable for working when the direction of the target current is a first direction to mirror the detection voltage and output the mirror voltage; the comparison unit is suitable for comparing the detection voltage and outputting a comparison signal when the direction of the target current is a second direction; the voltage division unit is suitable for dividing the mirror voltage and outputting the divided voltage; the sampling unit is configured to sample the divided voltage and the comparison signal to determine the overcurrent state of the target current. The circuit completes the overcurrent state detection under different current directions according to the divided voltage and the comparison signal determined based on the detection voltage, so that it can simultaneously meet the positive and negative overcurrent detection requirements.

Description

Technical Field

[0001] The present invention relates to the technical field of household electrical appliances, and in particular to a current sampling circuit, an overcurrent protection device, an intelligent power module and a household electrical appliance. Background Art

[0002] Current detection is crucial to the operational stability of electrical equipment. In related technologies, current sampling circuits are selected and applied based on the direction of current, and have a small scope of application, making it difficult to simultaneously meet the overcurrent detection requirements in both positive and negative directions. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems in the related art to a certain extent. To this end, the first object of the present invention is to provide a current sampling circuit, which completes overcurrent state detection under different current directions according to a divided voltage determined based on a detection voltage and a comparison signal, so that it can simultaneously meet the positive and negative overcurrent detection requirements.

[0004] The second objective of the present invention is to provide an overcurrent protection device.

[0005] The third objective of the present invention is to provide an intelligent power module.

[0006] A fourth objective of the present invention is to provide a household appliance.

[0007] To achieve the above-mentioned purpose, an embodiment of the first aspect of the present invention proposes a current sampling circuit, comprising: a detection unit, a mirror unit, a voltage divider unit, a comparison unit and a sampling unit, wherein the detection unit is suitable for detecting a target current to generate a detection voltage; the mirror unit is suitable for working when the direction of the target current is a first direction to mirror the detection voltage and output the mirror voltage; the comparison unit is suitable for comparing the detection voltage and outputting a comparison signal when the direction of the target current is a second direction, wherein the second direction is opposite to the first direction; the voltage divider unit is suitable for dividing the mirror voltage and outputting the divided voltage; the sampling unit is configured to sample the divided voltage and the comparison signal to determine the overcurrent state of the target current.

[0008] According to the current sampling circuit of the embodiment of the present invention, the target current is detected by the detection unit to generate a detection voltage, the mirror unit works when the direction of the target current is the first direction to mirror the detection voltage and output the mirror voltage, the comparison unit compares the detection voltage when the direction of the target current is the second direction and outputs a comparison signal, wherein the second direction is opposite to the first direction, the mirror voltage is divided by the voltage divider unit to output the divided voltage, and the sampling unit samples the divided voltage and the comparison signal to determine the overcurrent state of the target current. Thus, the circuit completes the overcurrent state detection under different current directions according to the divided voltage and the comparison signal determined based on the detection voltage, so that it can simultaneously meet the positive and negative overcurrent detection requirements.

[0009] In addition, the current sampling circuit according to the above embodiment of the present invention may also have the following additional technical features:

[0010] According to an embodiment of the present invention, the detection unit includes at least one current-sensing resistor, one end of the current-sensing resistor is grounded, and the other end of the current-sensing resistor serves as an output end of the detection unit.

[0011] According to one embodiment of the present invention, the mirror unit includes a first diode, a second diode and a first resistor, the anode of the first diode is connected to the anode of the second diode and then connected to one end of the first resistor, the other end of the first resistor is connected to a reference power supply, the cathode of the first diode is connected to the output end of the detection unit, and the cathode of the second diode is suitable for being connected to the voltage divider unit.

[0012] According to one embodiment of the present invention, when there are three current-sensing resistors, there are three mirror units, wherein the cathode of the first diode in each mirror unit is respectively connected to the other end of the corresponding current-sensing resistor among the three current-sensing resistors; and the cathodes of the second diodes in the three mirror units are connected together.

[0013] According to one embodiment of the present invention, the voltage divider unit includes: a second resistor, one end of the second resistor is connected to the cathode of the second diode; a third resistor, one end of the third resistor is connected to the other end of the second resistor and has a first node, the other end of the third resistor is grounded, wherein the first node serves as the output end of the voltage divider unit; a first capacitor, the first capacitor is connected in parallel with the third resistor.

[0014] According to one embodiment of the present invention, the comparison unit includes: a third diode, the cathode of the third diode is suitable for connecting to the output end of the detection unit; a fourth resistor, one end of the fourth resistor is connected to the anode of the third diode; a fifth resistor, one end of the fifth resistor is connected to the other end of the fourth resistor and has a second node, and the other end of the fifth resistor is connected to a reference power supply; a comparator, the negative input end of the comparator is connected to the second node, the positive input end of the comparator is connected to the threshold voltage providing end, and the output end of the comparator serves as the output end of the comparison unit.

[0015] According to one embodiment of the present invention, the comparison unit also includes: a fourth diode, an anode of the fourth diode is connected to the second node, and a cathode of the fourth diode is connected to the negative input terminal of the comparator; a sixth resistor, one end of the sixth resistor is connected to the cathode of the fourth diode, and the other end of the sixth resistor is grounded.

[0016] According to one embodiment of the present invention, the comparison unit also includes: a seventh resistor, one end of the seventh resistor is connected to the output end of the comparator, and the other end of the seventh resistor is connected to the reference power supply; a fifth diode, the anode of the fifth diode is connected to the output end of the comparator, and the cathode of the fifth diode is suitable for connecting to the sampling unit.

[0017] According to one embodiment of the present invention, the comparison unit also includes: an eighth resistor, one end of the eighth resistor is connected to a reference power supply; a ninth resistor, one end of the ninth resistor is connected to the other end of the eighth resistor and has a third node, the other end of the ninth resistor is grounded, and the third node serves as a threshold voltage providing end.

[0018] According to one embodiment of the present invention, when the detection unit includes three current-sensing resistors, there are three third diodes, and the cathode of each third diode is respectively connected to the other end of the corresponding current-sensing resistor among the three current-sensing resistors, and the anodes of the three third diodes are connected together and then connected to one end of the fourth resistor.

[0019] According to an embodiment of the present invention, the sampling unit includes a controller, and a sampling terminal of the controller is respectively connected to an output terminal of the voltage dividing unit and an output terminal of the comparison unit.

[0020] According to an embodiment of the present invention, the comparator may be integrated into a MCU (Microcontroller Unit) of the controller.

[0021] To achieve the above-mentioned purpose, the second aspect of the embodiment of the present invention proposes an overcurrent protection device, including: the above-mentioned current sampling circuit, suitable for detecting the target current to determine the overcurrent state of the target current; a controller, configured to generate an overcurrent protection signal according to the overcurrent state.

[0022] According to the overcurrent protection device of an embodiment of the present invention, the target current is detected by the above-mentioned current sampling circuit to determine the overcurrent state of the target current. The controller generates an overcurrent protection signal according to the overcurrent state. Based on the above-mentioned current sampling circuit, the overcurrent state detection under different current directions can be completed, thereby ensuring the positive and negative overcurrent protection effects.

[0023] To achieve the above-mentioned purpose, the third aspect of the embodiment of the present invention proposes an intelligent power module, including: a three-phase inverter bridge, the three-phase inverter bridge includes three-phase bridge arms, each phase arm of the three-phase bridge arm includes an upper bridge switch tube and a lower bridge switch tube; the above-mentioned current sampling circuit, the current sampling circuit is suitable for sampling the positive and negative currents of each phase of the three-phase inverter bridge.

[0024] According to the intelligent power module of the embodiment of the present invention, the three-phase inverter bridge includes a three-phase bridge arm, each phase arm of the three-phase bridge arm includes an upper bridge switch tube and a lower bridge switch tube, and the above-mentioned current sampling circuit samples the positive and negative current of each phase of the three-phase inverter bridge. Therefore, based on the above-mentioned current sampling circuit, the intelligent power module can realize overcurrent state detection under different current directions, so that it meets the positive and negative overcurrent detection requirements of the module and effectively protects the intelligent power module.

[0025] In addition, the intelligent power module according to the above embodiment of the present invention may also have the following additional technical features:

[0026] According to an embodiment of the present invention, when the current sampling circuit includes a current sensing resistor, one end of the current sensing resistor is grounded, and the other end of the current sensing resistor is respectively connected to the lower bridge switch tube in each phase bridge arm.

[0027] According to an embodiment of the present invention, when the current sampling circuit includes three current sensing resistors, one end of each current sensing resistor is grounded, and the other end of each current sensing resistor is connected to a corresponding lower bridge switch tube in each phase bridge arm.

[0028] To achieve the above-mentioned purpose, a fourth aspect of the present invention provides a household appliance, comprising: a motor; and the above-mentioned intelligent power module, wherein the intelligent power module is suitable for driving the motor.

[0029] According to the household appliance of the embodiment of the present invention, the motor is driven by the above-mentioned intelligent power module. Based on the above-mentioned intelligent power module, overcurrent state detection under different current directions can be completed, so that it meets the overcurrent detection requirements of the motor, improves the overcurrent protection effect on the motor operation, and ensures the operating stability of the household appliance.

[0030] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a connection diagram of a current sampling circuit according to an embodiment of the present invention;

[0032] Figure 2 A circuit diagram of a mirror unit according to a specific embodiment of the present invention Figure 1 ;

[0033] Figure 3 A circuit diagram of a mirror unit according to a specific embodiment of the present invention Figure 2 ;

[0034] Figure 4 is a circuit diagram of a current sensing resistor according to a specific embodiment of the present invention;

[0035] Figure 5 A circuit diagram of a comparison unit according to a specific embodiment of the present invention Figure 1 ;

[0036] Figure 6 A circuit diagram of a comparison unit according to a specific embodiment of the present invention Figure 2 ;

[0037] Figure 7 A circuit diagram of a comparison unit according to a specific embodiment of the present invention Figure 3 ;

[0038] Figure 8 A circuit diagram of a comparison unit according to a specific embodiment of the present invention Figure 4 ;

[0039] Fig. 9 is a circuit diagram of a current sampling circuit according to a specific embodiment of the present invention;

[0040] Fig.10 for Fig. 9 A current schematic diagram when the direction of the target current is a first direction;

[0041] Fig.11 for Fig. 9 A current schematic diagram when the direction of the target current is the second direction;

[0042] Fig.12 is a circuit diagram of a current sampling circuit according to another specific embodiment of the present invention;

[0043] Fig.13 is a block diagram of an overcurrent protection device according to an embodiment of the present invention;

[0044] Fig.14 is a circuit diagram of an overcurrent protection device according to a specific embodiment of the present invention;

[0045] Fig.15is a block diagram of an intelligent power module according to an embodiment of the present invention;

[0046] Fig.16 FIG. 4 is a block diagram of a household appliance according to an embodiment of the present invention. DETAILED DESCRIPTION

[0047] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0048] The current sampling circuit, overcurrent protection device, intelligent power module and household appliance proposed in the embodiments of the present invention are described below with reference to the accompanying drawings.

[0049] Figure 1 FIG. 4 is a connection diagram of a current sampling circuit according to an embodiment of the present invention.

[0050] like Figure 1 As shown, the current sampling circuit of the embodiment of the present invention may include: a detection unit 10 , a mirror unit 20 , a voltage dividing unit 30 , a comparison unit 40 and a sampling unit 50 .

[0051] Among them, the detection unit 10 is suitable for detecting the target current to generate a detection voltage. The mirror unit 20 is suitable for working when the direction of the target current is a first direction to mirror the detection voltage and output the mirror voltage. The comparison unit 40 is suitable for comparing the detection voltage and outputting a comparison signal when the direction of the target current is a second direction, wherein the second direction is opposite to the first direction. The voltage divider unit 30 is suitable for dividing the mirror voltage and outputting the divided voltage. The sampling unit 50 is configured to sample the divided voltage and the comparison signal to determine the overcurrent state of the target current.

[0052] The current sampling circuit of the present application is described in detail below by taking the first direction as a positive direction and the second direction as a negative direction as an example.

[0053] Specifically, the target current is detected by the detection unit 10, and a corresponding detection voltage is output according to the target current. The detection voltage corresponds to the polarity and magnitude of the target current. For example, when the direction of the target current is positive, the target current is a positive current, and the corresponding detection voltage is a positive voltage. As the target current increases in the positive direction, the detection voltage also gradually increases in the positive direction, that is, the positive current gradually increases, and the positive voltage also increases accordingly; when the direction of the target current is negative, the target current is a negative current, and the corresponding detection voltage is a negative voltage. As the target current increases in the negative direction, the detection voltage also gradually increases in the negative direction, that is, the negative current gradually increases, and the negative voltage also increases accordingly. It should be noted that the increase in the negative direction refers to the increase in the absolute value.

[0054] The mirror unit 20 and the comparison unit 40 receive the detection voltage. When the target current is a positive current, that is, the direction of the target current is a first direction, the comparison unit 40 does not output, and the mirror unit 20 mirrors the detection voltage to output a mirror voltage equal to the detection voltage to improve the sampling accuracy. The voltage divider unit 30 divides the mirror voltage and outputs it to the sampling unit 50. The sampling unit 50 compares the divided voltage output by the voltage divider unit 30 with the first preset overcurrent protection threshold. When the divided voltage reaches the first preset overcurrent protection threshold, it is considered that the target current has a forward overcurrent, otherwise, it is considered that the target current has not a forward overcurrent.

[0055] When the target current is a negative current, that is, the direction of the target current is the second direction, the mirror unit 20 and the voltage divider unit 30 do not output, and the comparison unit 40 compares the received detection voltage with the preset voltage threshold. When it is determined that the detection voltage drops to the preset voltage threshold, the comparison unit 40 outputs a comparison signal to the sampling unit 50, and the sampling unit 50 determines whether the target current is overcurrent based on the comparison signal. The comparison signal can be a level signal or a fixed voltage signal. For example, the sampling unit 50 can consider that the target current has a negative overcurrent when receiving the comparison signal, otherwise, it is considered that the target current has not a negative overcurrent. It can be understood that, when the target current is in the second direction, when the magnitude of the target current is small, the comparison unit 40 will not output a comparison signal when the detection voltage has not dropped to the preset voltage threshold, and when the target current is in the first direction and the detection voltage has not dropped to the preset voltage threshold, the comparison unit 40 will not output to the sampling unit 50, and the port of the sampling unit 50 is at a low level at this time, and when the detection voltage drops to the preset voltage threshold, the comparison unit 40 will output a comparison signal to the sampling unit 50, thereby a sudden change of the electrical signal will appear at the port where the sampling unit 50 is connected to the comparison unit 40, and the sampling unit 50 can determine whether there is an input of the comparison signal based on the port change.

[0056] In addition, the detection voltage is only used to trigger the output comparison signal of the comparison unit 40. The comparison signal actually output by the comparison unit 40 may not be affected by the polarity of the detection voltage, that is, it is not affected by the direction of the target current. When the target current is a negative current, the comparison signal output by the comparison unit 40 can still be a positive voltage, such as a pre-set voltage value, so that it is easier to meet sampling requirements and circuit layout.

[0057] In one implementation of the present invention, the sampling unit 50 can be provided with two connection ports, which are respectively connected to the voltage divider unit 30 and the comparison unit 40 through the two ports, and judge whether a positive overcurrent or a negative overcurrent occurs based on different control logics. For example, taking the sampling unit 50 being connected to the voltage divider unit 30 through port A and to the comparison unit 40 through port B as an example, it can be judged whether a positive overcurrent occurs by comparing the voltage value received at port A with the first preset overcurrent protection threshold, and it can be judged whether a negative overcurrent occurs by judging whether a sudden change occurs in the voltage at port B.

[0058] In another possible implementation of the present invention, since the comparison signal output by the sampling unit 50 can be a set voltage value, the voltage value of the comparison signal can also be set to be equal to or greater than the voltage value of the first preset overcurrent protection threshold. At this time, the sampling unit 50 can be connected to the voltage divider unit 30 and the comparison unit 40 at the same time through a connection port. During application, the voltage value of the connection port is compared with the first preset overcurrent protection threshold to determine whether a positive or negative overcurrent occurs.

[0059] Therefore, in this embodiment, when the direction of the target current is the first direction, the sampling unit 50 performs overcurrent state detection based on the voltage divided by the voltage divider unit 30 output, and when the direction of the target current is the second direction, the sampling unit 50 performs overcurrent state detection based on the comparison signal output by the comparison unit 40, so that it can be applied to the overcurrent detection requirements of positive and negative currents at the same time, ensuring the scope of application of the circuit.

[0060] Combination Figure 2 As shown, in one embodiment of the present invention, the detection unit 10 includes at least one current-sensing resistor Rs, one end of the current-sensing resistor Rs is grounded, and the other end of the current-sensing resistor Rs serves as an output end of the detection unit 10 .

[0061] That is to say, the current sensing resistor Rs is connected in series in the target circuit, and the detection voltage is the upper end voltage of the current sensing resistor Rs, satisfying the formula Vs=Rs*Is, where Vs is the detection voltage, Rs is the current sensing resistor, and Is is the target current flowing through the current sensing resistor.

[0062] In one embodiment of the present invention, the mirror unit 20 includes a first diode D1, a second diode D2 and a first resistor R1, the anode of the first diode D1 is connected to the anode of the second diode D2 and then connected to one end of the first resistor R1, the other end of the first resistor R1 is connected to the reference power supply Vdd, the cathode of the first diode D1 is connected to the output end of the detection unit 10, and the cathode of the second diode D2 is suitable for being connected to the voltage divider unit 30.

[0063] Specifically, when the direction of the target current is the first direction, that is, when the target current is a positive current, the first diode D1 is turned on, and the anode voltage of the first diode D1 is Vs+Vf1, wherein Vs is the detection voltage, and Vf1 is the voltage drop on the first diode D1, then the voltage value output through the cathode of the second diode D2 is Vs+Vf1-Vf2, wherein Vf1 is the voltage drop of the first diode D1, and Vf2 is the voltage drop of the second diode D2, Vf1=Vf2, thus, the mirror voltage output through the cathode of the second diode D2 is equal to the detection voltage Vs, that is, the voltage value of the mirror voltage is equal to the detection voltage, thereby avoiding the influence of the diode voltage drop on the sampling accuracy and improving the detection accuracy.

[0064] When the direction of the target current is the second direction, that is, when the target current is a negative current, the detection voltage is a negative voltage, the first diode D1 is turned on, and the second diode D2 is not turned on. At this time, the mirror unit 20 does not output the mirror voltage to the voltage divider unit 30, so that the voltage divider unit 30 has no voltage divider output.

[0065] Combination Figure 3 As shown, in one embodiment of the present invention, when there are three current-sense resistors Rs, there are three mirror units 20, wherein the cathode of the first diode D1 in each mirror unit 20 is respectively connected to the other end of the corresponding current-sense resistor Rs in the three current-sense resistors Rs; the cathodes of the second diodes D2 in the three mirror units 20 are connected together.

[0066] Specifically, the three current-sensing resistors are represented by Rsu, Rsv, and Rsw, respectively, and the corresponding detection voltages are the upper end voltages of the corresponding current-sensing resistors, respectively represented by Vsu, Vsv, and Vsw. The cathodes of the first diodes D1 in the three mirror units 20 are respectively connected to the other ends of the current-sensing resistors Rsu, Rsv, and Rsw, for obtaining the detection voltage on the corresponding current-sensing resistors, and outputting the corresponding mirror voltage, i.e., the received detection voltage, through the cathode of the corresponding second diode D2. The cathodes of the second diodes D2 in the three mirror units 20 are connected together to form a node, the voltage at the node being the maximum voltage value among the cathode voltages of the three second diodes D2, i.e., the maximum detection voltage among the detection voltages output by the three current-sensing resistors.

[0067] This embodiment outputs mirror voltages corresponding to the three detection voltages respectively through three mirror units 20, and outputs the maximum mirror voltage among the three mirror voltages, namely the maximum detection voltage, through a node. The voltage divider unit 30 divides the voltage and outputs a divided voltage corresponding to the maximum detection voltage. Therefore, the sampling unit 50 can determine the overcurrent state of the maximum target current among the three target currents according to the detection voltage to determine whether current overcurrent occurs in the first direction.

[0068] For further example, assume that three current sensing resistors are used for motor current detection, and the current sensing resistor Rs is connected in series in the motor drive circuit. Figure 4 As shown, the motor drive circuit includes a three-phase inverter bridge 1 composed of six switch tubes (respectively represented by U+, U-, V+, V-, W+, and W-). In the three-phase inverter bridge 1, the switch tubes are teamed in pairs to form three parallel bridge arms, and each bridge arm is formed with corresponding output nodes respectively connected to the lead-out ends of the three-phase windings of the motor 2. Specifically, the series-connected switch tubes U+ and U- constitute the first bridge arm, and the node U of the first bridge arm is connected to the U-phase winding of the motor 2; the series-connected switch tubes V+ and V- constitute the second bridge arm, and the node V of the second bridge arm is connected to the V-phase winding of the motor 2; the series-connected switch tubes W+ and W- constitute the third bridge arm, and the node W of the third bridge arm is connected to the W-phase winding of the motor 2. By controlling the conduction and disconnection of the switch tubes, the corresponding nodes of the three-phase inverter bridge 1 output corresponding electrical signals, thereby driving the motor 2 to run.

[0069] The three current-sensing resistors Rs are arranged corresponding to the three bridge arms of the three-phase inverter bridge 1, and are respectively connected in series between the lower bridge arm of the corresponding bridge arm and the ground. Specifically, one end of the current-sensing resistor Rsu for sampling the U-phase current is grounded, and the other end is connected to the switch tube U- to form a node u, which is an output end of the detection unit 10 corresponding to U, and is connected to the mirror unit 20 and the comparison unit 40 through the node u; one end of the current-sensing resistor Rsv for sampling the V-phase current is grounded, and the other end is connected to the switch tube V- to form a node v, which is an output end of the detection unit 10 corresponding to V, and is connected to the mirror unit 20 and the comparison unit 40 through the node v; one end of the current-sensing resistor Rsw for sampling the W-phase current is grounded, and the other end is connected to the switch tube W- to form a node w, which is an output end of the detection unit 10 corresponding to W, and is connected to the mirror unit 20 and the comparison unit 40 through the node w.

[0070] In this embodiment, the detection voltage is the upper terminal voltage of the current-sensing resistor. When the direction of the current flowing through the current-sensing resistor is from the switch tube to the ground, the direction of the target current flowing through the current-sensing resistor is positive, and the detection voltage is a positive voltage. When the direction of the current flowing through the current-sensing resistor is from the ground to the switch tube, the direction of the target current flowing through the current-sensing resistor is negative, and the detection voltage is a negative voltage. The cathode connection node of the three second diodes D2 outputs the maximum positive voltage in the detection voltage corresponding to the three-phase bridge arm, thereby realizing overcurrent detection of the maximum positive current in the three phases.

[0071] In one embodiment of the present invention, the voltage divider unit 30 includes: a second resistor R2, one end of the second resistor R2 is connected to the cathode of the second diode D2; a third resistor R3, one end of the third resistor R3 is connected to the other end of the second resistor R2 and has a first node a, and the other end of the third resistor R3 is grounded, wherein the first node a serves as the output end of the voltage divider unit 30; a first capacitor C1, and the first capacitor C1 is connected in parallel with the third resistor R3.

[0072] That is, the mirror voltage output by the mirror unit 20 generates a corresponding voltage-divided signal through the second resistor R2 and the third resistor R3, and the voltage-divided signal is output to the sampling unit 50 through the first node a. In actual application, the resistance values ​​of the second resistor R2 and the third resistor R3 can be adjusted so that the voltage-divided voltage is within a suitable voltage range, and the voltage-divided voltage output from the first node a is filtered through the first capacitor C1 to improve the sampling accuracy.

[0073] by Figure 2 For example, when the target current on the current sensing resistor Rs is a positive current, the detection voltage obtained by the current sensing resistor Rs is a positive voltage, the first diode D1 and the second diode D2 are both in the on state, and the voltage value output by the first diode D1 is equal to the voltage value of the detection voltage.

[0074] At this time, the relationship between the detection voltage, the voltage value received by the sampling unit 50 and the target current is as follows:

[0075] Vs=Rs*Is (1)

[0076]

[0077] Vf1=Vf2 (3)

[0078] Among them, Vs is the detection voltage, Rs is the resistance of the current detection resistor, Is is the target current, Ers is the receiving voltage of the sampling unit, R3 is the resistance of the third resistor, R2 is the resistance of the second resistor, Vf1 is the voltage drop of the first diode, and Vf2 is the voltage drop of the second diode.

[0079] Therefore, the sampling unit 50 can determine the magnitude of the target current according to the received voltage value based on formula (1), thereby sampling the target current in the first direction and determining the overcurrent state.

[0080] In addition, based on the above formulas (1)-(3), a first preset overcurrent protection threshold for determining whether an overcurrent occurs in the first direction can be preset. For example, a first target current threshold can be determined according to circuit requirements. When the target current reaches the first target current threshold, it is considered that the target current has a forward overcurrent. The first target current threshold is substituted into the above formula, and the voltage value calculated is the first preset overcurrent protection threshold.

[0081] like Figure 5 As shown, in one embodiment of the present invention, the comparison unit 40 includes: a third diode D3, the cathode of the third diode D3 is suitable for connecting to the output end of the detection unit 10; a fourth resistor R4, one end of the fourth resistor R4 is connected to the anode of the third diode D3; a fifth resistor R5, one end of the fifth resistor R5 is connected to the other end of the fourth resistor R4, and has a second node b, and the other end of the fifth resistor R5 is connected to the reference power supply Vdd; a comparator A1, the negative input end of the comparator A1 is connected to the second node b, the positive input end of the comparator A1 is connected to the threshold voltage providing end, and the output end of the comparator A1 serves as the output end of the comparison unit 40.

[0082] Specifically, when the target current flowing through the current sensing resistor Rs is in the first direction, that is, the target current is a positive current, the detection voltage output by the current sensing resistor Rs is a positive voltage, the voltage Vb output by the second node b is greater than the preset voltage threshold provided by the threshold voltage providing end, and the comparator A1 outputs a low level to the sampling unit 50.

[0083] When the target current flowing through the current-sensing resistor Rs is in the second direction, that is, when the target current is a negative current, the detection voltage output by the current-sensing resistor Rs is a negative voltage. When the negative current is small, the voltage Vb output by the second node b is still greater than the preset voltage threshold, so that the comparator A1 continues to output a low level. As the negative current gradually increases, the negative voltage gradually increases, the current flowing through the third diode D3 continues to increase, and the voltage Vb gradually decreases. When the voltage Vb decreases to the preset voltage threshold, the comparator A1 outputs a high level to the sampling unit 50, so that when the detection voltage drops to the preset voltage threshold, the comparison unit 40 outputs a comparison signal to the sampling unit 50, and the sampling unit 50 determines whether the target current is overcurrent based on the comparison signal.

[0084] This embodiment uses comparator A to trigger the comparison signal. Compared with the application of triodes, the protection speed is faster, and it has better anti-interference ability and more reliable protection.

[0085] like Figure 6 As shown, in one embodiment of the present invention, the comparison unit 40 also includes: a fourth diode D4, an anode of the fourth diode D4 is connected to the second node b, and a cathode of the fourth diode D4 is connected to the negative input terminal of the comparator A1; a sixth resistor R6, one end of the sixth resistor R6 is connected to the cathode of the fourth diode D4, and the other end of the sixth resistor R6 is grounded.

[0086] Specifically, this embodiment adjusts the voltage of the negative input terminal of the input comparator A1 through the fourth diode D4 and the sixth resistor R6. At the same time, the setting of the fourth diode D4 can also ensure the unidirectional conduction of the circuit, realize the unidirectional flow of current, and will not cause any impact on the branch where the fourth resistor R4 is located.

[0087] Figure 6 The comparison unit 40 in satisfies the following formula:

[0088] Vb=R6*I4+Vf4 (4)

[0089]

[0090]

[0091] Among them, Vb is the voltage of the second node b, R6 is the resistance of the sixth resistor, I4 is the current flowing through the fourth diode and the sixth resistor, Vf4 is the voltage drop of the fourth diode, Vdd is the voltage of the reference power supply, R5 is the resistance of the fifth resistor, I3 is the current flowing through the third diode and the fourth resistor, Vf3 is the voltage drop of the third diode, Vs is the current detection resistor, and R4 is the resistance of the fourth resistor.

[0092] Combining the above formulas (4)-(6), it can be seen that: as the detection voltage Vs increases in the positive direction, the current I3 flowing through the third diode and the fourth resistor decreases, the voltage Vb at the second node b gradually increases, and the current I4 flowing through the fourth diode and the sixth resistor increases. Therefore, the voltage Vb received by the negative input terminal of the comparator A1 continues to increase. As long as it is ensured that when the detection voltage Vs is 0, the voltage received by the negative input terminal of the comparator A1 is greater than the preset voltage threshold provided by the threshold voltage providing terminal, then when the detection voltage Vs increases in the positive direction, the comparator A1 can maintain a low output level.

[0093] When a negative current flows through the sampling resistor Rs, the detection voltage is a negative voltage. As the negative current on the sampling resistor Rs increases, the negative voltage also increases, the current I3 flowing through the third diode and the fourth resistor continues to increase, the voltage Vb at the second node b gradually decreases, the current I4 flowing through the fourth diode and the sixth resistor continues to decrease, and the voltage at the negative input terminal of the comparator A1 gradually decreases. After the voltage at the negative input terminal reaches the preset voltage threshold, the comparator A1 is turned off, and at this time, the comparator A1 outputs a high level.

[0094] It should be noted that in another implementation of the present invention, the fourth diode D4 may be replaced by a resistor, and the voltage of the second node b may be divided by the resistor and the sixth resistor R6 to adjust the negative input voltage of the input comparator A1.

[0095] like Figure 7 As shown, in one embodiment of the present invention, the comparison unit 40 further includes: a seventh resistor R7, one end of the seventh resistor R7 is connected to the output end of the comparator A1, and the other end of the seventh resistor R7 is connected to the reference power supply Vdd; a fifth diode D5, an anode of the fifth diode D5 is connected to the output end of the comparator A1, and a cathode of the fifth diode D5 is suitable for connecting to the sampling unit 50.

[0096] That is, when the voltage at the negative input terminal of the comparator A1 is greater than the preset voltage threshold provided by the threshold voltage providing terminal (including the case where the direction of the target current is the first direction and the target current is a positive current, and the direction of the target current is the second direction and the target current is a negative current, but the negative current is small), the comparator A1 outputs a low level, the reference power supply Vdd is grounded through the seventh resistor R7 and the comparator A1, the fifth diode D5 is not turned on, and the comparison unit 40 does not output. When the voltage at the negative input terminal of the comparator A1 reaches the preset voltage threshold provided by the threshold voltage providing terminal, the comparator A1 outputs a high level, and the reference power supply Vdd is passed through the seventh resistor R7 and the fifth diode D5 to the comparison unit 40 to achieve the output of the comparison signal.

[0097] In one embodiment of the present invention, the comparison unit 40 also includes: an eighth resistor R8, one end of the eighth resistor R8 is connected to the reference power supply Vdd; a ninth resistor R9, one end of the ninth resistor R9 is connected to the other end of the eighth resistor R8, and has a third node c, the other end of the ninth resistor R9 is grounded, and the third node c serves as a threshold voltage providing end.

[0098] That is to say, the divided voltage obtained by dividing the reference power supply Vdd by the eighth resistor R8 and the ninth resistor R9 is used as the preset voltage threshold and output to the positive input terminal of the comparator A1 for voltage comparison and judgment.

[0099] like Figure 8 As shown, in one embodiment of the present invention, when the detection unit 10 includes three current-sensing resistors Rs, there are three third diodes D3, and the cathode of each third diode D3 is respectively connected to the other end of the corresponding current-sensing resistor Rs among the three current-sensing resistors Rs, and the anodes of the three third diodes D3 are connected together and then connected to one end of the fourth resistor R4.

[0100] Specifically, the three current-sensing resistors Rs are represented by Rsu, Rsv and Rsw respectively, and the cathodes of the three third diodes D3 receive the detection voltages output by the three current-sensing resistors Rs respectively, and the detection voltages output by the current-sensing resistors Rsu, Rsv and Rsw are represented by Vsu, Vsv and Vsw respectively. Among them, the anode voltages of the three third diodes D3 are Vsu+Vf3, Vsv+Vf3, Vsw+Vf3 respectively.

[0101] The voltage at the node formed by the anode connection of the three third diodes D3 is the minimum voltage among the three anode voltages, that is, the minimum voltage among the three anode voltages is output through the anode connection node of the three third diodes D3, and the voltage of the second node b is adjusted based on the minimum voltage, so as to control the comparator A1 to generate a comparison signal. Since the minimum voltage among the three anode voltages is determined based on the minimum voltage among the three detection voltages, that is, the minimum current of the target current in the second direction flowing through the three current-sensing resistors is determined, wherein when the target current is in the second direction, the target current is a negative current, and the smaller the target current is, the larger the current value in the negative direction is, and the detection voltage is a negative voltage, and the smaller the detection voltage is, the larger the voltage value in the negative direction is, thus, the comparison unit 40 can control the output of the comparison signal based on the minimum current flowing through the three current-sensing resistors, that is, the maximum negative current, and the sampling unit 50 can judge the overcurrent state of the negative maximum current among the three target currents based on the comparison signal to determine whether there is a negative overcurrent among the three target currents.

[0102] like Fig. 9 As shown, in one embodiment of the present invention, the sampling unit 50 includes a controller 51, and the sampling end of the controller is respectively connected to the output end of the voltage divider unit 30 and the output end of the comparison unit 40. That is, the controller 51 is connected to the voltage divider unit 30 and the comparison unit 40 through the same port.

[0103] In the above embodiment, the high level is used as the comparison signal, which is only one possible implementation of the present application and can be set according to the actual situation. For example, a voltage signal can also be used as the comparison signal. Fig. 9 and Fig.10 As shown, the fifth diode D5 of the comparison unit 50 is connected to the third resistor R3. When the comparator A1 outputs a high level, the reference power supply Vdd, the seventh resistor R7, the fifth diode D5, and the third resistor R3 branch are turned on, and the comparison signal output to the controller 51 through the node a is a voltage signal. Fig. 9 and Fig.10 The working process of the current sampling circuit of the present application is illustrated by way of example.

[0104] Fig. 9Schematic diagram of a current sampling circuit using a current sensing resistor Rs.

[0105] The direction of the target current is as follows Fig.10 In the first direction shown, when the target current is a positive current, the voltage at the upper end of the current-sensing resistor Rs is a positive voltage, that is, the detection voltage is a positive voltage, and as the positive current increases, the detection voltage increases in the positive direction. The first diode D1 and the second diode D2 are turned on, and the mirror unit 20 outputs the mirror voltage to the voltage-dividing unit 30, and divides the mirror voltage through the second resistor R2 and the third resistor R3, and outputs the divided voltage to the sampling end of the controller 51. At the same time, the third diode D3 is turned on, but the voltage of the second node b is still greater than the divided voltage provided by the eighth resistor R8 and the ninth resistor R9, and the comparator A1 outputs a low level, the reference power supply Vdd is grounded through the seventh resistor R7 and the comparator A1, the comparator A1 does not output, and the comparison unit 40 does not work. When the direction of the target current is the first direction, the sampling unit 50 only receives the divided voltage, and determines the overcurrent state of the target current according to the divided voltage.

[0106] The direction of the target current is as follows Fig.11 In the second direction shown, when the target current is a negative current, the voltage at the upper end of the current-sensing resistor Rs is a negative voltage, that is, the detection voltage is a negative voltage, and as the negative current increases, the detection voltage increases in the negative direction. In the mirror unit 20, the first diode D1 is turned on, the second diode D2 is not turned on, and the mirror unit 20 does not output the mirror voltage. Therefore, the voltage divider unit 30 has no voltage divider output to the sampling end of the controller 51, and the mirror unit 20 and the voltage divider unit 30 do not work. At the same time, the third diode D3 is turned on, but the voltage at the second node b changes with the change of the target current. When the voltage at the second node b is reduced to the voltage divider voltage provided by the eighth resistor R8 and the ninth resistor R9, the comparator A1 outputs a high level, the reference power supply Vdd is grounded through the seventh resistor R7, the fifth diode D5, and the third resistor R3, and the comparison unit 40 outputs a comparison signal to the sampling unit 50 through the node a. When the direction of the target current is the second direction, the sampling unit 50 only receives the comparison signal and determines the overcurrent state of the target current according to the comparison signal.

[0107] Further, when the voltage at the second node b of the comparison unit 40 is reduced to the divided voltage provided by the eighth resistor R8 and the ninth resistor R9, the following formula can be satisfied:

[0108]

[0109] Vcomp2+Vf4=Vb (8)

[0110] Vcomp2=I4*R6 (9)

[0111]

[0112]

[0113] Vs=Is*Rs (12)

[0114] Among them, Vcomp1 is the voltage of the positive input terminal of the comparator A1, R9 is the resistance value of the ninth resistor, Vdd is the voltage of the reference power supply, R8 is the resistance value of the eighth resistor, Vcomp2 is the voltage of the negative input terminal of the comparator A2, Vf4 is the voltage drop of the fourth diode, Vb is the voltage of the second node, I4 is the current flowing through the fourth diode and the sixth resistor, R6 is the resistance value of the sixth resistor, Vs is the detection voltage, Vf3 is the voltage drop of the third diode, R4 is the resistance value of the fourth resistor, I3 is the current flowing through the third diode, R5 is the resistance value of the fifth resistor, Is is the target current, and Rs is the resistance value of the current sensing resistor.

[0115] Thus, the above formulas (7)-(11) can be combined to pre-set the second target current threshold for triggering the comparison unit 40 to send a comparison signal. When the target current reaches the second target current threshold, it is considered that the target current has a negative overcurrent, the voltage at the negative input terminal of the comparator A1 is equal to the voltage at the positive input terminal of the comparator A1, and the comparison unit 40 sends a comparison signal to the controller 51. In addition, the voltage value of the comparison signal can be set to be equal to the first preset overcurrent protection threshold for judging a positive overcurrent through circuit parameter setting. At this time, the controller 51 can directly compare the received comparison signal with the first preset overcurrent protection threshold to judge whether the target current has an overcurrent.

[0116] Based on the above content, it can be known that by adjusting the parameters such as capacitors and resistors in the circuit, effective overcurrent detection of positive and negative currents on the current sensing resistor Rs can be achieved.

[0117] Fig.10 The schematic diagram of the current sampling circuit using three current sensing resistors is shown in FIG. Figure 4 The motor drive circuit shown.

[0118] During the motor current sampling process, the currents flowing through the three current-sensing resistors are Iu, Iv, and Iw, respectively, and satisfy Iu+Iv+Iw=0. When one-phase current is positive and the other two-phase currents are negative, the positive current is larger and the negative current is smaller, and there is a risk of positive overcurrent; when one-phase current is negative and the other two-phase currents are positive, the negative current is larger and the positive current is smaller, and there is a risk of negative overcurrent.

[0119] Assuming that Iu is a positive current and Iv and Iw are negative currents, the second diode D2 corresponding to the V phase and W phase is not conducting, and the mirror voltage received by the voltage divider unit 30 is Vsu, which is divided by the voltage divider unit 30 and output to the controller 51. At the same time, Iv and Iw are small negative voltages, so the comparator A1 continues to output a low level, and the comparison unit 40 does not output a comparison signal. Therefore, the sampling unit 50 determines whether an overcurrent occurs based on the received divided voltage.

[0120] Assuming that Iu is a negative current and Iv and Iw are positive currents, then the second diode D2 corresponding to U is not conducting, and the second diode D2 corresponding to V and W is conducting. At this time, the mirror voltage output by the cathode connection node of the three second diodes D2 is the maximum voltage of Vsv and Vsw, and the voltage divider unit 30 divides the voltage and outputs the corresponding divided voltage to the controller 51. At the same time, when the negative current of the U phase is small, the comparator A1 still outputs a low level, and no comparison signal is output. The voltage received by the controller 51 is only the voltage signal output by the voltage divider unit 30. As the negative current of the U phase increases, until the voltage at the negative input terminal of the comparator A1 drops to be equal to the voltage at the positive input terminal, the comparator A1 outputs a high level, and the comparison unit 40 outputs a comparison signal to the controller 51. At this time, the voltage at the input terminal of the controller 51 increases suddenly, and the controller 51 receives the comparison signal and the divided voltage at the same time, thereby completing the overcurrent judgment.

[0121] In summary, by adjusting the parameters of each electrical component in the circuit, effective protection of the positive and negative maximum currents on any phase current sensing resistor can be achieved.

[0122] This embodiment can realize positive and negative overcurrent detection of three-phase sampling by adding a small number of devices, and is also applicable to the case where there is no built-in comparator in the chip.

[0123] In summary, according to the current sampling circuit of the embodiment of the present invention, the target current is detected by the detection unit to generate a detection voltage, the mirror unit works when the direction of the target current is the first direction to mirror the detection voltage and output the mirror voltage, the comparison unit compares the detection voltage when the direction of the target current is the second direction and outputs a comparison signal, wherein the second direction is opposite to the first direction, the mirror voltage is divided by the voltage divider unit to output the divided voltage, and the sampling unit samples the divided voltage and the comparison signal to determine the overcurrent state of the target current. Thus, the circuit completes the overcurrent state detection under different current directions according to the divided voltage and the comparison signal determined based on the detection voltage, so that it can simultaneously meet the positive and negative overcurrent detection requirements.

[0124] Corresponding to the above embodiment, the present invention also proposes an overcurrent protection device.

[0125] like Fig.13 As shown, the overcurrent protection device of the embodiment of the present invention comprises: the above-mentioned current sampling circuit 100 and the controller 200, wherein the current sampling circuit 100 is suitable for detecting the target current to determine the overcurrent state of the target current. The controller 200 is configured to generate an overcurrent protection signal according to the overcurrent state.

[0126] Specifically, the current sampling circuit 100 detects the target current and sends the determined overcurrent state of the target current to the controller 200. When the controller 200 determines that the target current is overcurrent according to the overcurrent state, it sends an overcurrent protection signal to trigger the overcurrent protection action and perform overcurrent protection control on the target circuit to ensure the overcurrent protection effect. For example, when the overcurrent protection device is applied to motor overcurrent protection, the specific connection method of the overcurrent detection circuit 100 can refer to the above Figure 4 After the sampling unit 50 of the current sampling circuit 100 sends the confirmed overcurrent state to the controller 200, the controller 200 outputs a corresponding overcurrent protection signal when determining that a current overcurrent occurs according to the overcurrent state, so as to control the output disconnection of the three-phase inverter bridge 1, complete the overcurrent protection of the motor 2, and ensure the stability of the motor operation.

[0127] For example, combining Fig.14 As shown, the controller 200 and the sampling unit 50 of the current sampling circuit 100 are integrated in the chip of the IPM (Intelligent Power Module) module, wherein the output end of the IPM module is connected to the motor, and the control end of the IPM module is connected to the MCU to receive the PWM (Pulse width modulation) signal output by the MCU, and control the internal switch tube through the PWM signal to output the corresponding three-phase electrical signal to drive the motor to operate.

[0128] The three current-sensing resistors Rsu, Rsv, and Rsw are connected between the corresponding chip pins NU, NV, and NW of the three bridge arms of the IPM module and the ground, so as to realize the sampling of the three-phase current and generate the corresponding detection voltage. The chip pin RS of the IPM module is the input end of the sampling unit 50, and the controller 200 is connected to the sampling unit 50. The sampling unit 50 detects the overcurrent state of the target current in different directions based on the divided voltage output by the voltage divider unit 30 or the trigger voltage output by the trigger unit 40, and sends it to the controller 200. When the controller 200 determines that an overcurrent occurs according to the received overcurrent state, it controls the output of the IPM module to disconnect and sends an overcurrent reminder to the MCU to stop the MCU from outputting the PWM signal to complete the overcurrent protection.

[0129] Therefore, in the absence of a built-in comparator in the MCU chip, this application can also achieve three-phase sampling positive and negative current overcurrent protection by adding a minimum of components, effectively protecting the IPM module and motor while reducing application costs.

[0130] According to the overcurrent protection device of an embodiment of the present invention, the target current is detected by the above-mentioned current sampling circuit to determine the overcurrent state of the target current. The controller generates an overcurrent protection signal according to the overcurrent state. Based on the above-mentioned current sampling circuit, the overcurrent state detection under different current directions can be completed, thereby ensuring the positive and negative overcurrent protection effects.

[0131] Corresponding to the above embodiment, the present invention further proposes an intelligent power module.

[0132] like Fig.15 As shown, the intelligent power module 300 of the embodiment of the present invention includes: a three-phase inverter bridge 310 and a current sampling circuit 100, wherein the three-phase inverter bridge 310 includes a three-phase bridge arm, each phase arm of the three-phase bridge arm includes an upper bridge switch tube and a lower bridge switch tube, and the current sampling circuit 100 is suitable for sampling the positive and negative currents of each phase of the three-phase inverter bridge 310.

[0133] In one embodiment of the present invention, when the current sampling circuit 100 includes a current sensing resistor, one end of the current sensing resistor is grounded, and the other end of the current sensing resistor is connected to the lower bridge switch tube in each phase bridge arm.

[0134] In one embodiment of the present invention, when the current sampling circuit 100 includes three current sensing resistors, one end of each current sensing resistor is grounded, and the other end of each current sensing resistor is connected to a corresponding lower bridge switch tube in each phase bridge arm.

[0135] According to the intelligent power module of the embodiment of the present invention, the three-phase inverter bridge includes a three-phase bridge arm, and each phase arm of the three-phase bridge arm includes an upper bridge switch tube and a lower bridge switch tube respectively. The above-mentioned current sampling circuit samples the positive and negative current of each phase of the three-phase inverter bridge. Therefore, based on the above-mentioned current sampling circuit, overcurrent state detection under different current directions can be completed, so that it meets the positive and negative overcurrent detection requirements of the intelligent power module, and effectively protects the intelligent power module.

[0136] Corresponding to the above embodiment, the present invention also proposes a household appliance.

[0137] like Fig.16 As shown, the household appliance 400 according to the embodiment of the present invention includes a motor 410 and the above-mentioned intelligent power module 300 , and the intelligent power module 300 is suitable for driving the motor.

[0138] According to the household appliance of the embodiment of the present invention, the motor is driven by the above-mentioned intelligent power module. Based on the above-mentioned intelligent power module, overcurrent state detection under different current directions can be completed, so that it meets the positive and negative overcurrent detection requirements, improves the overcurrent protection effect, and ensures the operating stability of the household appliance.

[0139] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0140] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0141] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0142] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A current sampling circuit, characterized in that: include: A detection unit, a mirror unit, a voltage divider unit, a comparison unit and a sampling unit, wherein: The detection unit is adapted to detect the target current to generate a detection voltage; The mirror unit is adapted to operate when the direction of the target current is a first direction, so as to mirror the detection voltage and output a mirror voltage; The comparison unit is adapted to compare the detection voltage and output a comparison signal when the direction of the target current is a second direction, wherein the second direction is opposite to the first direction; The voltage dividing unit is adapted to divide the mirror voltage and output a divided voltage; The sampling unit is configured to sample the divided voltage and the comparison signal to determine an overcurrent state of the target current.

2. The current sampling circuit according to claim 1, characterized in that: The detection unit includes at least one current-sensing resistor, one end of the current-sensing resistor is grounded, and the other end of the current-sensing resistor serves as an output end of the detection unit.

3. The current sampling circuit according to claim 2, characterized in that: The mirror unit includes a first diode, a second diode and a first resistor, wherein an anode of the first diode is connected to an anode of the second diode and then connected to one end of the first resistor, the other end of the first resistor is connected to a reference power supply, a cathode of the first diode is connected to an output end of the detection unit, and a cathode of the second diode is suitable for being connected to the voltage divider unit.

4. The current sampling circuit according to claim 3, characterized in that: When there are three current-sense resistors, there are three mirror units, wherein: The cathode of the first diode in each of the mirror units is respectively connected to the other end of the corresponding current sensing resistor among the three current sensing resistors; The cathodes of the second diodes in the three mirror units are connected together.

5. The current sampling circuit according to claim 3, characterized in that: The voltage dividing unit comprises: a second resistor, one end of the second resistor being connected to the cathode of the second diode; a third resistor, one end of the third resistor being connected to the other end of the second resistor and having a first node, and the other end of the third resistor being grounded, wherein the first node serves as an output end of the voltage dividing unit; A first capacitor is connected in parallel with the third resistor.

6. The current sampling circuit according to any one of claims 1 to 5, characterized in that: The comparison unit comprises: a third diode, wherein a cathode of the third diode is suitable for connecting to an output terminal of the detection unit; a fourth resistor, one end of which is connected to the anode of the third diode; a fifth resistor, one end of the fifth resistor being connected to the other end of the fourth resistor and having a second node, and the other end of the fifth resistor being connected to a reference power supply; A comparator, wherein the negative input terminal of the comparator is connected to the second node, the positive input terminal of the comparator is connected to the threshold voltage providing terminal, and the output terminal of the comparator serves as the output terminal of the comparison unit.

7. The current sampling circuit according to claim 6, characterized in that: The comparison unit further includes: a fourth diode, wherein an anode of the fourth diode is connected to the second node, and a cathode of the fourth diode is connected to the negative input terminal of the comparator; A sixth resistor, one end of the sixth resistor is connected to the cathode of the fourth diode, and the other end of the sixth resistor is grounded.

8. The current sampling circuit according to claim 6, characterized in that: The comparison unit further includes: a seventh resistor, one end of the seventh resistor being connected to the output end of the comparator, and the other end of the seventh resistor being connected to the reference power supply; A fifth diode, wherein an anode of the fifth diode is connected to the output end of the comparator, and a cathode of the fifth diode is suitable for connecting to the sampling unit.

9. The current sampling circuit according to claim 6, characterized in that: The comparison unit further includes: an eighth resistor, one end of which is connected to the reference power supply; A ninth resistor, one end of the ninth resistor is connected to the other end of the eighth resistor and has a third node, the other end of the ninth resistor is grounded, and the third node serves as the threshold voltage providing end.

10. The current sampling circuit according to claim 6, characterized in that: In the case where the detection unit includes three current-sensing resistors, there are three third diodes, the cathode of each of the third diodes is respectively connected to the other end of the corresponding current-sensing resistor among the three current-sensing resistors, and the anodes of the three third diodes are connected together and then connected to one end of the fourth resistor.

11. The current sampling circuit according to claim 6, characterized in that: The sampling unit comprises a controller, and a sampling end of the controller is respectively connected to an output end of the voltage dividing unit and an output end of the comparison unit.

12. The current sampling circuit according to claim 11, characterized in that: The comparator may be integrated into the MCU of the controller.

13. An overcurrent protection device, characterized in that: include: The current sampling circuit according to any one of claims 1 to 12, adapted to detect the target current to determine an overcurrent state of the target current; The controller is configured to generate an overcurrent protection signal according to the overcurrent state.

14. An intelligent power module, characterized in that: include: A three-phase inverter bridge, wherein the three-phase inverter bridge comprises three-phase bridge arms, and each phase bridge arm of the three-phase bridge arms comprises an upper bridge switch tube and a lower bridge switch tube; According to any one of claims 1-12, the current sampling circuit is suitable for sampling the positive and negative current of each phase of the three-phase inverter bridge.

15. The intelligent power module according to claim 14, characterized in that: In the case where the current sampling circuit includes a current sensing resistor, one end of the current sensing resistor is grounded, and the other end of the current sensing resistor is respectively connected to the lower bridge switch tube in each phase bridge arm.

16. The intelligent power module according to claim 14, characterized in that: When the current sampling circuit includes three current sensing resistors, one end of each current sensing resistor is grounded, and the other end of each current sensing resistor is connected to a corresponding lower bridge switch tube in each phase bridge arm.

17. A household appliance, characterized in that: include: Motor; The intelligent power module according to any one of claims 14 to 16, wherein the intelligent power module is suitable for driving the motor.

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