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

Abstract

The present invention discloses a current detection circuit, an overcurrent protection device, an intelligent power module and a household appliance, wherein the circuit comprises: a detection unit, which is suitable for detecting a target current to generate a detection voltage; a clamping unit, which is suitable for clamping the detection voltage to output a clamping voltage; a voltage dividing unit, which is connected to the clamping unit and is suitable for dividing the clamping voltage to output a divided voltage when the direction of the target current is a first direction; a triggering unit, which is connected to the clamping unit and is suitable for generating a triggering voltage according to the clamping voltage when the direction of the target current is a second direction, wherein the second direction is opposite to the first direction; and a sampling unit, which is configured to sample the divided voltage and the triggering voltage to determine the overcurrent state of the target current. The circuit determines the overcurrent state of the target current in the first direction or the second direction by sampling the divided voltage or the triggering voltage, thereby meeting 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 detection 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 detection 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 detection circuit, which determines the overcurrent state of the target current in the first direction or the second direction by sampling the divided voltage or the trigger voltage, thereby meeting 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 detection circuit, comprising: a detection unit, suitable for detecting a target current to generate a detection voltage; a clamping unit, suitable for clamping the detection voltage to output a clamping voltage; a voltage dividing unit, the voltage dividing unit is connected to the clamping unit, and is suitable for dividing the clamping voltage to output a divided voltage when the direction of the target current is a first direction; a triggering unit, the triggering unit is connected to the clamping unit, and is suitable for generating a trigger voltage according to the clamping voltage when the direction of the target current is a second direction, wherein the second direction is opposite to the first direction; and a sampling unit, configured to sample the divided voltage and the trigger voltage to determine the overcurrent state of the target current.

[0008] According to the current detection circuit of the embodiment of the present invention, the target current is detected by the detection unit to generate a detection voltage, the detection voltage is clamped by the clamping unit to output the clamping voltage, the voltage dividing unit is connected to the clamping unit, and the clamping voltage is divided by the voltage dividing unit when the direction of the target current is a first direction to output the divided voltage, the triggering unit is connected to the clamping unit, and the triggering unit generates a trigger voltage according to the clamping voltage when the direction of the target current is a second direction, wherein the second direction is opposite to the first direction, and the sampling unit samples the divided voltage and the trigger voltage to determine the overcurrent state of the target current. The circuit determines the overcurrent state of the target current in the first direction by sampling the divided voltage, and determines the overcurrent state of the target current in the second direction by sampling the trigger voltage, thereby meeting the positive and negative overcurrent detection requirements.

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

[0010] According to one embodiment of the present invention, the clamping unit includes a first diode and a second diode, the anode of the first diode is connected to the cathode of the second diode to form a first node, the first node is suitable for connecting to the output end of the detection unit, the cathode of the first diode is suitable for connecting to the voltage divider unit, and the anode of the second diode is suitable for connecting to the trigger unit.

[0011] 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.

[0012] According to one embodiment of the present invention, when there are three current-sensing resistors, there are three clamping units, wherein the first node of each clamping unit is respectively connected to the other end of the corresponding current-sensing resistor among the three current-sensing resistors; after the cathodes of the first diodes in the three clamping units are connected together, they are suitable for connecting to the voltage divider unit, and after the anodes of the second diodes in the three clamping units are connected together, they are suitable for connecting to the trigger unit.

[0013] According to one embodiment of the present invention, the voltage divider unit includes: a first resistor, one end of which is suitable for connecting to the clamping unit; a second resistor, one end of which is connected to the other end of the first resistor and has a second node, the other end of the second resistor is grounded, and the second node is suitable for connecting to the sampling end of the sampling unit.

[0014] According to an embodiment of the present invention, the voltage dividing unit further includes: a first capacitor, which is connected in parallel with the second resistor.

[0015] According to one embodiment of the present invention, the trigger unit includes: a third resistor, one end of the third resistor is suitable for connecting to the clamping unit; a fourth resistor, one end of the fourth resistor is connected to the other end of the third resistor and has a third node, and the other end of the fourth resistor is connected to a reference power supply; a first triode, the base of the first triode is connected to the third node, and the emitter of the first triode is grounded; a fifth resistor, one end of the fifth resistor is connected to the collector of the first triode, and the other end of the fifth resistor is connected to the reference power supply; a third diode, the anode of the third diode is connected to the collector of the first triode, and the cathode of the third diode is suitable for connecting to the sampling end of the sampling unit.

[0016] According to one embodiment of the present invention, the trigger unit also includes: a sixth resistor, one end of the sixth resistor is connected to the third node, and the other end of the sixth resistor is connected to the base of the first transistor; and a seventh resistor, the seventh resistor is connected between the base and the emitter of the first transistor.

[0017] According to an embodiment of the present invention, the trigger unit further includes: an eighth resistor, one end of the eighth resistor is connected to the cathode of the third diode, and the other end of the eighth resistor is suitable for connecting to the sampling end of the sampling unit.

[0018] 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 detection 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.

[0019] According to the overcurrent protection device of the embodiment of the present invention, through the above-mentioned current detection circuit, it is suitable for detecting the target current 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 detection circuit, the overcurrent state of the target current in the first direction or the second direction is determined by sampling the voltage divider voltage or the trigger voltage, thereby meeting the positive and negative overcurrent detection requirements and ensuring the positive and negative overcurrent protection effects.

[0020] 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 in the three-phase bridge arm includes an upper bridge switch tube and a lower bridge switch tube; the above-mentioned current detection circuit, the current detection circuit is suitable for detecting the positive and negative current of each phase of the three-phase inverter bridge.

[0021] 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 detection circuit detects the positive and negative current of each phase of the three-phase inverter bridge. Based on the above-mentioned current detection circuit, the overcurrent state of the target current in the first direction or the second direction is determined by sampling the voltage divider voltage or the trigger voltage, thereby meeting the positive and negative overcurrent detection requirements and ensuring the operating stability of the module.

[0022] In addition, the intelligent power module according to the above embodiment of the present invention may also have the following additional technical features:

[0023] According to an embodiment of the present invention, when the current detection 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.

[0024] According to an embodiment of the present invention, when the current detection circuit includes three current detection resistors, one end of each current detection resistor is grounded, and the other end of each current detection resistor is connected to a corresponding lower bridge switch tube in each phase bridge arm.

[0025] To achieve the above-mentioned purpose, a fourth aspect of the present invention provides a household appliance, a motor; and the above-mentioned intelligent power module, which is suitable for driving the motor.

[0026] According to the household appliance of the embodiment of the present invention, the motor is driven by the above-mentioned intelligent power module, and the operation stability of the household appliance is ensured based on the above-mentioned intelligent power module.

[0027] 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

[0028] Figure 1 is a connection diagram of a current detection circuit according to an embodiment of the present invention;

[0029] Figure 2 is a circuit diagram of a current detection circuit according to a specific embodiment of the present invention;

[0030] Figure 3 is a circuit diagram of a current detection circuit according to another specific embodiment of the present invention;

[0031] Figure 4 is a connection diagram of a current sensing resistor according to a specific embodiment of the present invention;

[0032] Figure 5 for Figure 2 A circuit schematic diagram when the direction of the target current is a first direction;

[0033] Figure 6 is a circuit diagram of a current detection circuit according to a specific embodiment of the present invention when the direction of the target current is the second direction;

[0034] Figure 7 is a circuit diagram of a current detection circuit according to a specific embodiment of the present invention when the direction of the target current is the second direction;

[0035] Figure 8 is a circuit diagram of a current detection circuit according to another specific embodiment of the present invention;

[0036] Fig. 9 is a block diagram of an overcurrent protection device according to an embodiment of the present invention;

[0037] Fig.10 is a circuit diagram of an overcurrent protection device according to a specific embodiment of the present invention;

[0038] Fig.11 is a block diagram of an intelligent power module according to an embodiment of the present invention;

[0039] Fig.12 FIG. 4 is a block diagram of a household appliance according to an embodiment of the present invention. DETAILED DESCRIPTION

[0040] 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.

[0041] The current detection 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.

[0042] Figure 1 FIG. 4 is a connection diagram of a current detection circuit according to an embodiment of the present invention.

[0043] like Figure 1 As shown, the current detection circuit of the embodiment of the present invention may include: a detection unit 10 , a clamping unit 20 , a voltage dividing unit 30 , a triggering unit 40 and a sampling unit 50 .

[0044] Among them, the detection unit 10 is suitable for detecting the target current to generate a detection voltage. The clamping unit 20 is suitable for clamping the detection voltage to output the clamping voltage. The voltage dividing unit 30 is connected to the clamping unit 20, and the voltage dividing unit 30 is suitable for dividing the clamping voltage when the direction of the target current is a first direction to output the divided voltage. The trigger unit 40 is connected to the clamping unit 20, and the trigger unit 40 is suitable for generating a trigger voltage according to the clamping voltage when the direction of the target current is a second direction, wherein the second direction is opposite to the first direction. The sampling unit 50 is configured to sample the divided voltage and the trigger voltage to determine the overcurrent state of the target current.

[0045] Specifically, taking the first direction as a positive direction and the second direction as a negative direction as an example, the detection unit 10 detects the magnitude and polarity of the target current to generate a corresponding detection voltage. For example, when the direction of the target current is the first direction, the target current is a positive current, and the corresponding detection voltage is a positive voltage; when the direction of the target current is the second direction, the target current is a negative current, and the corresponding detection voltage is a negative voltage, and the magnitude of the detection voltage is positively correlated with the magnitude of the target current.

[0046] The detection voltage is clamped by the clamping unit 20 to obtain a clamping voltage. It can be understood that the clamping voltage changes with the change of the received detection voltage.

[0047] When the direction of the target current is the first direction, the target current is a positive current, and the detection voltage is a positive voltage. As the positive current increases, the positive voltage gradually increases, and the clamping voltage also gradually increases. After the clamping voltage output by the clamp is divided by the voltage divider unit 30, the divided voltage is output to the sampling unit 50. The sampling unit 50 samples the divided voltage and compares the voltage value obtained by the sampling with the first preset overcurrent protection threshold. When it is determined that the voltage value obtained by the sampling is greater than or equal to 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.

[0048] When the direction of the target current is the second direction, the target current is a negative current, and the detection voltage is a negative voltage. As the negative current increases, the negative voltage also gradually increases, and the clamping voltage gradually decreases. The clamping voltage output by the clamping is output to the trigger unit 40. The trigger unit 40 generates a trigger voltage to the sampling unit 50 when the clamping voltage is reduced to a preset voltage threshold. The sampling unit 50 samples the trigger voltage and compares the voltage value obtained by the sampling with the second preset overcurrent protection threshold. When it is determined that the voltage value obtained by the sampling is greater than or equal to the first preset overcurrent protection threshold, it is considered that the target current has a negative overcurrent, otherwise it is considered that the target current has not a negative overcurrent. It can be understood that the trigger unit 40 does not output a trigger voltage when the clamping voltage is not reduced to the preset voltage threshold.

[0049] In addition, the clamping voltage output by the clamping unit 20 is only used as the output trigger signal of the trigger unit 40. The trigger voltage actually output by the trigger unit 40 may not be affected by the polarity of the current clamping voltage, that is, it is not affected by the direction of the target current. When the target current is negative, the trigger voltage output by the trigger unit 40 may be a positive voltage, such as a preset voltage value, which is easier to meet the sampling requirements and circuit layout. Of course, the trigger voltage may also change with the change of the target current, which is not limited here.

[0050] Based on the above content, the present application can also use a preset overcurrent protection threshold to judge the overcurrent state of the target current in different directions. Specifically, the first current threshold in the first direction corresponding to the target current and the second current threshold in the second direction can be pre-set, wherein when the target current reaches the first current threshold, it is considered that a positive overcurrent occurs, and when the target current reaches the second current threshold, it is considered that a negative overcurrent occurs. By adjusting the circuit parameters, the trigger voltage output by the trigger unit 40 when the target current reaches the second current threshold is equal to the divided voltage output by the voltage divider unit 30 when the target current reaches the first current threshold. Thus, the first preset overcurrent protection threshold and the second preset overcurrent protection threshold can use the same overcurrent protection threshold, and the sampling unit 50 samples the received divided voltage or trigger voltage, and compares the voltage value obtained by the sampling with the overcurrent protection threshold. When it is determined that the voltage value obtained by the sampling is greater than or equal to the overcurrent protection threshold, it is considered that the target current has overcurrent, otherwise, it is considered that the target current has not overcurrent. Therefore, the sampling unit 50 may have only one input terminal, through which the voltage divider unit 30 and the trigger unit 40 are simultaneously connected, or may have two input terminals, through which the outputs of the voltage divider unit 30 and the trigger unit 40 are respectively received, which is not limited here.

[0051] 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 divider voltage output by the voltage divider unit 30, and when the direction of the target current is the second direction, the sampling unit 50 performs overcurrent state detection based on the trigger voltage output by the trigger 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.

[0052] In one embodiment of the present invention, the clamping unit 20 includes a first diode D1 and a second diode D2, the anode of the first diode D1 is connected to the cathode of the second diode D2 to form a first node a, the first node a is suitable for connecting to the output end of the detection unit 10, the cathode of the first diode D1 is suitable for connecting to the voltage divider unit 30, and the anode of the second diode D2 is suitable for connecting to the trigger unit 40.

[0053] Specifically, Figure 2As shown, the clamping unit 20 outputs a corresponding clamping voltage to the voltage dividing unit 30 through the cathode of the first diode D1 , and provides a corresponding clamping voltage to the triggering unit 40 through the anode of the second diode D2 .

[0054] When the direction of the target current is the first direction, the target current is a positive current, the detection voltage output by the detection unit 10 is a positive voltage, the first diode D1 and the second diode D2 are turned on, and the clamping voltage output by the first diode D1 is Vrs-Vf1, where Vrs is the detection voltage, and Vf1 is the voltage drop of the first diode D1. The voltage divider 30 receives the clamping voltage and performs voltage division processing. The clamping voltage output by the second diode D2 is Vrs+Vf2. In this process, the clamping voltage input to the trigger unit 40 is relatively large, and the trigger voltage will not be triggered. The sampling unit 50 confirms the overcurrent state of the target current according to the voltage divider.

[0055] When the direction of the target current is the second direction, the target current is a negative current, the detection voltage output by the detection unit 10 is a negative voltage, the first diode D1 is not conducting, the second diode D2 is conducting, the voltage divider unit 30 has no clamping voltage input, and the voltage divider unit 30 does not output. The trigger unit 40 receives the clamping voltage output by the second diode D2, and generates a trigger voltage according to the received clamping voltage, and the sampling unit 50 confirms the overcurrent state of the target current according to the trigger voltage.

[0056] It should be noted that when the target current is in the first direction and is a positive current, the detection voltage is a positive voltage. Accordingly, as the target current gradually increases in the positive direction, the detection voltage gradually increases in the positive direction. Since the detection voltage is a positive voltage, Vrs+Vf2 gradually increases; when the target current is in the second direction and is a negative current, the detection voltage is a negative voltage. Accordingly, as the target current gradually increases in the negative direction, the target voltage gradually increases in the negative direction. Since the detection voltage is a negative voltage, Vrs+Vf2 will gradually decrease.

[0057] 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 .

[0058] That is, the detection voltage is the upper terminal voltage of the current sensing resistor Rs, satisfying the formula Vrs=Rs*Is, where Vrs is the detection voltage, Rs is the current sensing resistor, and Is is the target current flowing through the current sensing resistor.

[0059] Combination Figure 3As shown, in one embodiment of the present invention, when there are three current-sensing resistors Rs, there are three clamping units 10, wherein the first node a of each clamping unit 20 is respectively connected to the other end of the corresponding current-sensing resistor Rs among the three current-sensing resistors Rs; after the cathodes of the first diodes D1 in the three clamping units 20 are connected together, they are suitable for connecting to the voltage divider unit 30, and after the anodes of the second diodes D2 in the three clamping units 20 are connected together, they are suitable for connecting to the trigger unit 40.

[0060] Specifically, the three current-sense resistors Rs are represented by Rsu, Rsv and Rsw respectively, and the three clamping units 20 receive the detection voltages output by the current-sense resistors Rsu, Rsv and Rsw respectively through the node a, and the detection voltages corresponding to the outputs of the current-sense resistors Rsu, Rsv and Rsw are represented by Vrsu, Vrsv and Vrsw respectively. Among them, the cathode voltages of the first diodes D1 in the three clamping units 20 are Vrsu-Rsu, Vrsv-Rsv, and Vrsw-Rsw respectively.

[0061] The voltage at the node formed by connecting the cathodes of the three first diodes D1 is the maximum voltage among the three cathode voltages, that is, the maximum voltage among the three cathode voltages is output to the voltage divider unit 30 through the cathode connection node of the three first diodes D1, so that the maximum voltage is divided by the voltage divider unit 30 and fed back to the sampling unit 50. Since the maximum voltage among the three cathode voltages is determined based on the maximum voltage among the three detection voltages, that is, the maximum current of the target current flowing through the three current-sense resistors in the first direction, the sampling unit 50 can detect the forward overcurrent state of the maximum target current based on the divided voltage to determine whether there is a positive overcurrent among the three target currents.

[0062] The voltage at the node formed by connecting the anodes of the three second diodes D2 is the minimum voltage among the three anode voltages, that is, the minimum voltage among the three anode voltages is output to the trigger unit 40 through the anode connection node of the three second diodes D2, and the trigger unit 40 generates a trigger voltage based on the minimum voltage and feeds it back to the sampling unit 50. 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, 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, therefore, the sampling unit 50 can judge the overcurrent state of the maximum negative current value among the three target currents based on the trigger voltage to determine whether there is a negative overcurrent among the three target currents.

[0063] Furthermore, the connection method of the three detection resistors Rs of the present application is illustrated below by taking the current sampling circuit applied to motor control and the target current being the phase current of the motor as an example.

[0064] Combination 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.

[0065] The number of the three detection units 10 is three, and they are arranged corresponding to the three bridge arms of the three-phase inverter bridge 1. The three current-sensing resistors Rs 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 in the detection unit 10 for sampling the U-phase current is grounded, and the other end is connected to the switch tube U- and forms a node u, which is the output end of the detection unit 10 corresponding to U, and is connected to the clamping unit 20 through the node u; one end of the current-sensing resistor Rsv in the detection unit 10 for sampling the V-phase current is grounded, and the other end is connected to the switch tube V- and forms a node v, which is the output end of the detection unit 10 corresponding to V, and is connected to the clamping unit 20 through the node v; one end of the current-sensing resistor Rsw in the detection unit 10 for sampling the W-phase current is grounded, and the other end is connected to the switch tube W- and forms a node w, which is the output end of the detection unit 10 corresponding to W, and is connected to the clamping unit 20 through the node w.

[0066] Combination Figure 5 As shown, in one embodiment of the present invention, the voltage dividing unit 30 includes: a first resistor R1, one end of the first resistor R1 is suitable for connecting to the clamping unit 20; a second resistor R2, one end of the second resistor R2 is connected to the other end of the first resistor R1 and has a second node b, the other end of the second resistor R2 is grounded, and the second node b is suitable for connecting to the sampling end of the sampling unit 50.

[0067] That is, the clamping voltage output by the clamping unit 20 is divided by the first resistor R1 and the second resistor R2 , and then the second node b sends the divided voltage to the sampling unit 50 .

[0068] When a positive current flows through the current-sensing resistor Rs, the voltage at the upper end of the current-sensing resistor Rs is a positive voltage, and the clamping unit 20 outputs the clamping voltage to the voltage-dividing unit 30 through the first diode D1. The voltage-dividing unit 30 divides the clamping voltage through the first resistor R1 and the second resistor R2 and outputs it to the sampling unit 50. At this time, the receiving voltage of the sampling unit 50 is the divided voltage, and the detection voltage and the receiving voltage of the sampling unit 50 satisfy the following formula:

[0069] Vrs=Rs*Is (1)

[0070]

[0071] Wherein, Vrs is the detection voltage, Rs is the resistance of the current detection resistor, Is is the target current, Ers is the received voltage of the sampling unit 50, R2 is the resistance of the second resistor, R1 is the resistance of the first resistor, and Vf1 is the voltage drop of the first diode.

[0072] Therefore, the sampling unit 50 can calculate the current target current through formula (1) (2), and can also pre-set a first preset overcurrent protection threshold for determining whether a forward overcurrent occurs based on formula (1) (2). For example, the first current value can be set based on actual needs. When the target current reaches the first current value, it is considered that a forward overcurrent occurs. Then, the first current value is substituted into formula (1) (2) to calculate the corresponding voltage Ers, which is used as the first preset overcurrent protection threshold.

[0073] Furthermore, the sampling unit 50 can directly compare the received divided voltage with the first preset overcurrent protection threshold to determine whether a positive overcurrent occurs, or it can calculate the received divided voltage based on formulas (1) (2) to obtain a corresponding target current, and then compare the target current with the first current value to determine whether a positive overcurrent occurs.

[0074] In one embodiment of the present invention, the voltage dividing unit 30 further includes: a first capacitor C1, which is connected in parallel with the second resistor R2. That is, the voltage divided voltage output by the voltage dividing unit 30 is filtered by the first capacitor C1 to improve the detection accuracy.

[0075] In one embodiment of the present invention, the trigger unit 40 includes: a third resistor R3, one end of the third resistor R3 is suitable for connecting to the clamping unit 20; a fourth resistor R4, one end of the fourth resistor R4 is connected to the other end of the third resistor R3 and has a third node c, and the other end of the fourth resistor R4 is connected to the reference power supply Vdd; a first transistor Q1, the base b of the first transistor Q1 is connected to the third node c, and the emitter e of the first transistor Q1 is grounded; a fifth resistor R5, one end of the fifth resistor R5 is connected to the collector c of the first transistor Q1, and the other end of the fifth resistor R5 is connected to the reference power supply Vdd; a third diode D3, the anode of the third diode D3 is connected to the collector c of the first transistor Q1, and the cathode of the third diode D3 is suitable for connecting to the sampling end of the sampling unit 50.

[0076] Specifically, the trigger voltage 50 controls the first diode Q1 through the voltage Vc at the third node c. When the voltage Vc is greater than the preset voltage threshold, the first diode Q1 is turned on, the fifth resistor R5 is grounded through the first diode Q1, the third diode D3 is not turned on, and the trigger unit 40 does not output the trigger voltage to the sampling unit. When the voltage Vc is less than or equal to the preset voltage threshold, the first diode Q1 is turned off, the reference power supply Vdd, the fifth resistor R5, and the third diode D3 branch are turned on, thereby outputting the trigger voltage to the sampling unit 50. The conduction schematic diagram is shown in FIG. Figure 6 shown.

[0077] It is understandable that in Figure 6 In the embodiment shown, the trigger voltage is a high level. In addition to the above setting method, a specific voltage value can also be used as the trigger voltage, such as Figure 7 As shown, when the first diode Q1 is turned off, the reference power supply Vdd, the fifth resistor R5, the third diode D3, and the resistor R41 branch are turned on. At this time, the trigger voltage output to the sampling unit 50 is the upper end voltage of the resistor R41, and the output trigger voltage is filtered by the capacitor C41 to ensure the detection accuracy in the second direction.

[0078] Below Figure 7 Taking the trigger unit 40 as an example, the current sampling circuit is as follows: Figure 2 As shown, the voltage dividing unit 30 and the triggering unit 40 share the second resistor R2 and the first capacitor C1.

[0079] When the target current is in the first direction, Figure 5As shown, the target current is a positive current, the detection voltage outputted from the upper end of the current sensing resistor Rs is a positive voltage, the first diode D1 and the second diode D2 remain turned on, and the voltage divider unit 30 divides the clamping voltage outputted from the first diode D1 through the first resistor R1 and the second resistor R2, and outputs the corresponding divided voltage to the sampling unit 50. At the same time, the first transistor Q1 remains turned on, the reference power supply Vdd passes through the fifth resistor R5 and the first transistor Q1 to the ground, and the trigger unit 40 does not output. At this time, the detection voltage satisfies formula (1), the received voltage of the sampling unit 50 is the divided voltage that satisfies formula (2), and the voltage of the third node c satisfies the following formula:

[0080] Vc=Vrs+Vf2+i3*R3 (3)

[0081] Wherein, Vc is the voltage of the third node, Vrs is the detection voltage, Vfs is the voltage drop of the second diode, i3 is the current flowing through the third resistor, and R3 is the resistance value of the third resistor. Since the voltage of the third node c is greater than the preset voltage threshold, the first transistor Q1 can be kept turned on, and when the target current is in the first direction, the trigger unit 40 does not output the trigger voltage.

[0082] When the target current is in the second direction, combined Figure 7 As shown, the target current is a negative current, the voltage outputted from the upper end of the current-sense resistor Rs is a negative voltage, the first diode D1 is not conducting, and the second diode D2 remains conducting. At this time, the voltage-dividing unit 30 has no clamping voltage input and does not output the divided voltage to the sampling unit 50. As the negative current on the current-sense resistor Rs increases, the current flowing through the second diode D2 and the third resistor R3 increases continuously, and the voltage of the third node c decreases continuously. After the voltage of the third node c decreases to a preset threshold, the first transistor Q1 is turned off. At this time, the reference power supply Vdd, the fifth resistor R5, the third diode D3, the second resistor R2 and the first capacitor C1 branch are conducting, and the trigger unit 40 outputs the trigger voltage to the sampling unit 50. The sampling unit 50 determines the overcurrent state of the target current according to the received trigger voltage.

[0083] When the target current is in the second direction, the current value that enables the trigger unit 40 to generate the trigger voltage can be set by the following formula:

[0084]

[0085] Among them, Vc is the voltage of the third node, Vf2 is the voltage drop of the second diode, Is is the target current, Rs is the resistance of the current sensing resistor, R3 is the resistance of the third resistor, Vdd is the voltage value of the reference power supply, and R4 is the resistance of the fourth resistor.

[0086] Furthermore, when the current sensing resistor Rs is three, the current sensing circuit is as follows: Figure 3As shown, the arrangement of the current sensing resistor Rs is as follows Figure 4 The figure is used in the motor current sampling process. Among them, the three current sensing resistors Rs are represented by Rsu, Rsv and Rsw respectively, and the corresponding detection voltages are Vrsu, Vrsv and Vrsw.

[0087] During the current sampling process, the currents flowing through the three current-sense resistors Rs 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.

[0088] Assuming that Iu is a positive current, and Iv and Iw are negative currents, then the first diode D1 corresponding to the V phase and W phase is not conducting, and at this time the clamping voltage received by the voltage divider unit 30 is Vrsu-Vf1, and the voltage divider unit 30 divides the clamping voltage and outputs it to the sampling unit 50. At the same time, Iv and Iw are relatively small negative voltages, so the voltage at the third node c can still maintain the first diode Q1 to remain conducting, and the trigger unit 40 does not output the trigger voltage. Therefore, the sampling unit 50 determines whether an overcurrent occurs based on the received divided voltage.

[0089] Assuming that Iu is a negative current and Iv and Iw are positive currents, then the first diode D1 corresponding to U is not conducting, and the first diode D1 corresponding to V phase and W is conducting. At this time, the clamping voltage output by the cathode connection node of the three first diodes D1 is the maximum voltage of Vrsv-Vrf1 and Vrsw-Vrf1, and the voltage divider unit 30 divides the voltage and outputs the corresponding divided voltage to the sampling unit 50. At the same time, when the negative current of the U phase is small, the first diode Q1 remains conducting, the trigger unit 40 has no output, and the voltage received by the sampling unit 50 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 third node c decreases to the preset voltage threshold, the first diode Q1 is turned off, and the trigger unit 40 outputs the corresponding trigger voltage to the sampling unit 50. At this time, the voltage at the input end of the sampling unit 50 increases suddenly, and the sampling unit 50 receives the trigger voltage and the divided voltage at the same time, thereby completing the overcurrent judgment.

[0090] In summary, by adjusting the parameters of each electrical component in the circuit, effective protection of the maximum positive and negative currents on any phase current sensing resistor can be achieved.

[0091] Combination Figure 8As shown, in one embodiment of the present invention, the trigger unit 40 also includes: a sixth resistor R6, one end of the sixth resistor R6 is connected to the third node c, and the other end of the sixth resistor R6 is connected to the base b of the first transistor Q1; a seventh resistor R7, and the seventh resistor R7 is connected between the base b and the emitter e of the first transistor Q1.

[0092] That is, the voltage Vc output from the third node c is divided by the sixth resistor R6 and the seventh resistor R7 to obtain a divided voltage Vc. Then the divided voltage The first transistor Q1 is controlled.

[0093] In one embodiment of the present invention, the trigger unit 40 further includes: an eighth resistor R8, one end of the eighth resistor R8 is connected to the cathode of the third diode D3, and the other end of the eighth resistor R8 is suitable for connecting to the sampling end of the sampling unit 50. That is, further current limiting operation is performed through the eighth resistor R8.

[0094] In summary, according to the current detection circuit of the embodiment of the present invention, the target current is detected by the detection unit to generate a detection voltage, the detection voltage is clamped by the clamping unit to output the clamping voltage, the voltage divider unit is connected to the clamping unit, and the voltage divider unit divides the clamping voltage to output the divided voltage when the direction of the target current is a first direction, and the trigger unit is connected to the clamping unit, and the trigger unit generates a trigger voltage according to the clamping voltage when the direction of the target current is a second direction, wherein the second direction is opposite to the first direction, and the sampling unit samples the divided voltage and the trigger voltage to determine the overcurrent state of the target current. The circuit determines the overcurrent state of the target current in the first direction by sampling the divided voltage, and determines the overcurrent state of the target current in the second direction by sampling the trigger voltage, thereby meeting the positive and negative overcurrent detection requirements.

[0095] Corresponding to the above embodiment, the present invention also proposes an overcurrent protection device.

[0096] like Fig. 9 As shown, the overcurrent protection device of the embodiment of the present invention includes: the above-mentioned current detection circuit 100 and the controller 200. Among them, the current detection 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.

[0097] Specifically, the current detection circuit 100 detects the target current, determines whether the target current is in an overcurrent state, and sends it to the controller 200. When the controller 200 determines that the target current is overcurrent, it sends an overcurrent protection signal to trigger the overcurrent protection action to perform overcurrent protection control on the target circuit to ensure the overcurrent protection effect. For example, when the current detection circuit 100 is applied to motor overcurrent protection, the specific connection method can refer to the above Figure 4 , when the current detection circuit 100 sends the confirmed overcurrent state to the controller 200, the controller 200 outputs a corresponding overcurrent protection signal when determining that an overcurrent occurs according to the overcurrent state to control the output disconnection of the three-phase inverter bridge 1, thereby completing the overcurrent protection of the motor 2 and ensuring the stability of the motor operation.

[0098] For example, combining Fig.10 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 (Microcontroller Unit) to receive the PWM 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.

[0099] 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.

[0100] 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.

[0101] According to the overcurrent protection device of the embodiment of the present invention, through the above-mentioned current detection circuit, it is suitable for detecting the target current 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 detection circuit, the overcurrent state of the target current in the first direction or the second direction is determined by sampling the voltage divider voltage or the trigger voltage, thereby meeting the positive and negative overcurrent detection requirements and ensuring the positive and negative overcurrent protection effects.

[0102] Corresponding to the above embodiment, the present invention further proposes an intelligent power module.

[0103] like Fig.11 As shown, the intelligent power module 300 of the embodiment of the present invention includes: a three-phase inverter bridge 310 and the above-mentioned current detection circuit 100. Among them, the three-phase inverter bridge 310 includes a three-phase bridge arm, and each phase bridge arm in the three-phase bridge arm includes an upper bridge switch tube and a lower bridge switch tube. The current detection circuit 100 is suitable for detecting the positive and negative current of each phase of the three-phase inverter bridge 310.

[0104] In one embodiment of the present invention, when the current detection circuit 100 includes a current detection resistor, one end of the current detection resistor is grounded, and the other end of the current detection resistor is connected to the lower bridge switch tube in each phase bridge arm.

[0105] In one embodiment of the present invention, when the current detection circuit 100 includes three current detection resistors, one end of each current detection resistor is grounded, and the other end of each current detection resistor is connected to a corresponding lower bridge switch tube in each phase bridge arm.

[0106] 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 detection circuit detects the positive and negative current of each phase of the three-phase inverter bridge. Based on the above-mentioned current detection circuit, the overcurrent state of the target current in the first direction or the second direction is determined by sampling the voltage divider voltage or the trigger voltage, thereby meeting the positive and negative overcurrent detection requirements and ensuring the operating stability of the module.

[0107] Corresponding to the above embodiment, the present invention also proposes a household appliance.

[0108] like Fig.12 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 410 .

[0109] According to the household appliance of the embodiment of the present invention, the motor is driven by the above-mentioned intelligent power module, and the operation stability of the household appliance is ensured based on the above-mentioned intelligent power module.

[0110] 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.

[0111] 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.

[0112] 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.

[0113] 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 detection circuit, characterized in that: include: A detection unit, adapted to detect a target current to generate a detection voltage; A clamping unit, adapted to clamp the detection voltage to output a clamping voltage; a voltage dividing unit, the voltage dividing unit being connected to the clamping unit and being adapted to divide the clamping voltage to output a divided voltage when the direction of the target current is a first direction; a trigger unit, the trigger unit being connected to the clamp unit and being adapted to generate a trigger voltage according to the clamp voltage when the direction of the target current is a second direction, wherein the second direction is opposite to the first direction; The sampling unit is configured to sample the divided voltage and the trigger voltage to determine an overcurrent state of the target current.

2. The current detection circuit according to claim 1, characterized in that: The clamping unit includes a first diode and a second diode, the anode of the first diode is connected to the cathode of the second diode to form a first node, the first node is suitable for connecting to the output end of the detection unit, the cathode of the first diode is suitable for connecting to the voltage divider unit, and the anode of the second diode is suitable for connecting to the trigger unit.

3. The current detection circuit according to claim 2, 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.

4. The current detection circuit according to claim 3, characterized in that: When there are three current-sense resistors, there are three clamping units, wherein: The first node of each clamping unit is respectively connected to the other end of the corresponding current sensing resistor among the three current sensing resistors; After the cathodes of the first diodes in the three clamping units are connected together, they are suitable for connecting to the voltage dividing unit, and after the anodes of the second diodes in the three clamping units are connected together, they are suitable for connecting to the triggering unit.

5. The current detection circuit according to any one of claims 1 to 4, characterized in that: The voltage dividing unit comprises: a first resistor, one end of which is suitable for connecting to the clamping unit; A second resistor, one end of the second resistor is connected to the other end of the first resistor and has a second node, the other end of the second resistor is grounded, and the second node is suitable for connecting to the sampling end of the sampling unit.

6. The current detection circuit according to claim 5, characterized in that: The voltage dividing unit further includes: A first capacitor is connected in parallel with the second resistor.

7. The current detection circuit according to any one of claims 1 to 4, characterized in that: The trigger unit comprises: a third resistor, one end of which is suitable for connecting to the clamping unit; a fourth resistor, one end of the fourth resistor being connected to the other end of the third resistor and having a third node, and the other end of the fourth resistor being connected to a reference power supply; A first triode, wherein a base of the first triode is connected to the third node, and an emitter of the first triode is grounded; a fifth resistor, one end of the fifth resistor being connected to the collector of the first transistor, and the other end of the fifth resistor being connected to the reference power supply; A third diode, wherein the anode of the third diode is connected to the collector of the first transistor, and the cathode of the third diode is suitable for connecting to the sampling end of the sampling unit.

8. The current detection circuit according to claim 7, characterized in that: The trigger unit also includes: a sixth resistor, one end of the sixth resistor being connected to the third node, and the other end of the sixth resistor being connected to the base of the first transistor; A seventh resistor is connected between the base and the emitter of the first transistor.

9. The current detection circuit according to claim 8, characterized in that: The trigger unit also includes: An eighth resistor, one end of the eighth resistor is connected to the cathode of the third diode, and the other end of the eighth resistor is suitable for connecting to the sampling end of the sampling unit.

10. An overcurrent protection device, characterized in that: include: The current detection circuit according to any one of claims 1 to 9, 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.

11. 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 1-9, the current detection circuit is suitable for detecting the positive and negative current of each phase of the three-phase inverter bridge.

12. The intelligent power module according to claim 11, characterized in that: In the case where the current detection circuit includes a current detection resistor, one end of the current detection resistor is grounded, and the other end of the current detection resistor is respectively connected to the lower bridge switch tube in each phase bridge arm.

13. The intelligent power module according to claim 11, characterized in that: When the current detection circuit includes three current detection resistors, one end of each current detection resistor is grounded, and the other end of each current detection resistor is connected to a corresponding lower bridge switch tube in each phase bridge arm.

14. A household appliance, characterized in that: include: Motor; The intelligent power module according to any one of claims 11 to 13, wherein the intelligent power module is suitable for driving the motor.

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