Current monitoring circuit of H-bridge driving motor

Abstract

The utility model discloses a current monitoring circuit of an H-bridge driving motor, which comprises an H-bridge driving unit, a voltage division sampling unit and a clamping protection unit, and is characterized in that the voltage division sampling unit is connected with the H-bridge driving unit so as to divide the voltage at the two ends of a direct-current motor, so that the voltage is controlled within a voltage range capable of being sampled by a microcontroller; the clamping protection unit is connected with the voltage division sampling unit and an ADC port of the microcontroller so as to protect the ADC port of the microcontroller, so that the microcontroller can monitor the current of the DC motor through the ADC port, and therefore, the on-resistance of the MOS tube of the H-bridge driving unit is used as a sampling current, and the DC motor can be driven by the H-bridge driving unit. Current monitoring is realized in cooperation with the voltage division sampling unit and the clamping protection unit, the cost is low, and the monitoring effect is good.

Description

TECHNICAL FIELD

[0001] The utility model relates to current voltage monitoring technical field, especially relate to a current monitoring circuit of H bridge drive motor. BACKGROUND

[0002] In the related art, the current monitoring circuit of the existing H bridge drive motor as shown in the figure usually adopts a current sensor or a shunt to monitor the current of the motor. Figure 1 However, the current sensor is expensive and bulky, requiring a certain space. The shunt is prone to heating, increasing additional loss and requiring heat dissipation, resulting in high cost and poor monitoring effect. SUMMARY

[0003] The utility model at least solves one of the above technical problems. To this end, the utility model aims to provide a current monitoring circuit of H bridge drive motor, which uses the on-resistance of the MOS tube of the H bridge drive unit as the sampling current, cooperates with the voltage dividing sampling unit and the clamping protection unit to realize current monitoring, and has low cost and good monitoring effect.

[0004] To achieve the above purpose, the utility model provides a current monitoring circuit of H bridge drive motor, which comprises: an H bridge drive unit, the H bridge drive unit comprising a DC motor; a voltage dividing sampling unit, the voltage dividing sampling unit being connected with the H bridge drive unit to divide the voltage across the DC motor, so that the voltage is controlled within the voltage range that can be sampled by the microcontroller; and a clamping protection unit, the clamping protection unit being connected with the voltage dividing sampling unit and the ADC port of the microcontroller to protect the ADC port of the microcontroller, so that the microcontroller can monitor the current of the DC motor through the ADC port.

[0005] The current monitoring circuit of H bridge drive motor according to the utility model uses the on-resistance of the MOS tube of the H bridge drive unit as the current sampling element, reduces the voltage across the DC motor to the range that can be sampled by the microcontroller through the voltage dividing resistor, and protects the ADC port from high voltage damage through the clamping diode, thereby integrating voltage and current monitoring functions without introducing additional loss and keeping low cost.

[0006] In addition, the current monitoring circuit of H bridge drive motor according to the utility model can have the following additional technical features:

[0007] Specifically, the H-bridge driving unit further comprises a first MOS transistor, a second MOS transistor, a third MOS transistor and a fourth MOS transistor, the drain of the first MOS transistor is connected to the voltage terminal, the source of the first MOS transistor is connected to the drain of the third MOS transistor, the source of the third MOS transistor is grounded, the drain of the second MOS transistor is connected to the voltage terminal, the source of the second MOS transistor is connected to the drain of the fourth MOS transistor, and the source of the fourth MOS transistor is grounded.

[0008] Specifically, one end of the DC motor is connected between the source of the first MOS transistor and the drain of the third MOS transistor, and the other end of the DC motor is connected between the source of the second MOS transistor and the drain of the fourth MOS transistor.

[0009] Specifically, the voltage division sampling unit comprises a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor and a seventh resistor, one end of the first resistor is connected to a first power terminal, the other end of the first resistor is connected to one end of the third resistor, and has a first node, the other end of the third resistor is connected to one end of the DC motor, one end of the fifth resistor is connected to one end of the DC motor, the other end of the fifth resistor is connected to one end of the seventh resistor, and has a third node, the other end of the seventh resistor is grounded, one end of the second resistor is connected to the first power terminal, the other end of the second resistor is connected to one end of the fourth resistor, and has a second node, the other end of the fourth resistor is connected to the other end of the DC motor, one end of the sixth resistor is connected to the other end of the DC motor, and the other end of the sixth resistor is connected to the third node.

[0010] Specifically, the first ADC port of the microcontroller is connected to the first node, the second ADC port of the microcontroller is connected to the second node, and the third ADC port of the microcontroller is connected to the third node.

[0011] Specifically, the clamping protection unit comprises a first diode, a second diode and a third diode, the negative electrode of the first diode is connected to a second power terminal, the positive electrode of the first diode is connected to the first node, the negative electrode of the second diode is connected to the second power terminal, the positive electrode of the second diode is connected to the second node, the negative electrode of the third diode is connected to the second power terminal, and the positive electrode of the third diode is connected to the third node.

[0012] Optionally, a temperature sensor is further included, which is close to or arranged in the fourth MOS transistor to monitor the junction temperature of the fourth MOS transistor.

[0013] Optionally, it also includes a temperature sensor, which is located near or inside the third MOSFET to monitor the junction temperature of the third MOSFET. Attached Figure Description

[0014] Figure 1 The circuit schematic of the current monitoring circuit for an existing H-bridge drive motor;

[0015] Figure 2 The circuit diagram is shown for a current monitoring circuit of an H-bridge drive motor according to an embodiment of the present invention.

[0016] Figure 3 R of a MOS transistor according to an embodiment of the present invention DS(on) A schematic diagram showing the relationship between the value and the current;

[0017] Figure 4 R of a MOS transistor according to an embodiment of the present invention DS(on) A schematic diagram showing the relationship between the value and the junction temperature. Detailed Implementation

[0018] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this utility model, and should not be construed as limiting this utility model.

[0019] To better understand the above technical solutions, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0020] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0021] refer to Figure 2 As shown, the current monitoring circuit for the H-bridge driven motor proposed in this embodiment of the present invention includes an H-bridge drive unit 10, a voltage divider sampling unit 20, and a clamping protection unit 30.

[0022] The H-bridge driving unit 10 includes a direct current motor M; the voltage dividing and sampling unit 20 is connected with the H-bridge driving unit 10, so as to divide the voltage at both ends of the direct current motor, and control the voltage within the voltage range that can be sampled by the microcontroller; the clamping protection unit 30 is connected with the voltage dividing and sampling unit 20 and the ADC port of the microcontroller, so as to protect the ADC port of the microcontroller, and enable the microcontroller to monitor the current of the direct current motor through the ADC port.

[0023] It should be noted that the ADC port is an analog-digital conversion interface, which is used to convert the sampled analog signal into a digital signal for processing by the microcontroller, and the analog signal sampled by the ADC port is the voltage at both ends of the direct current motor. These voltages are divided by the voltage dividing and sampling unit 20, and then converted into a voltage range that can be processed by the ADC port of the microcontroller (MCU). When the direct current motor is working, voltages will be generated at both ends of the motor. These voltages reflect the working state of the motor, including the speed and load of the motor. Through the voltage dividing and sampling unit 20, the voltage at both ends of the direct current motor is divided to a voltage level suitable for sampling by the ADC port. In this way, the ADC port can safely measure these voltages without being damaged by excessively high voltages. The analog voltage signal sampled by the ADC port is converted into a digital signal, which can be further processed and analyzed by the microcontroller to monitor and control the working state of the motor. In addition, the clamping protection unit 30 performs clamping protection to prevent the voltage of the direct current motor from damaging the ADC port of the MCU.

[0024] As an embodiment, the H-bridge driving unit 10 further includes a first MOS tube Q1, a second MOS tube Q2, a third MOS tube Q3 and a fourth MOS tube Q4. The drain of the first MOS tube Q1 is connected with a voltage terminal VPP, the source of the first MOS tube Q1 is connected with the drain of the third MOS tube Q3, the source of the third MOS tube Q3 is grounded, the drain of the second MOS tube Q2 is connected with the voltage terminal VPP, the source of the second MOS tube Q2 is connected with the drain of the fourth MOS tube Q4, and the source of the fourth MOS tube Q4 is grounded.

[0025] As an embodiment, one end of the direct current motor M is connected between the source of the first MOS tube Q1 and the drain of the third MOS tube Q3, and the other end of the direct current motor M is connected between the source of the second MOS tube Q2 and the drain of the fourth MOS tube Q4.

[0026] It should be noted that the first MOS tube Q1, the second MOS tube Q2, the third MOS tube Q3 and the fourth MOS tube Q4 are the core part of the H-bridge driving circuit, which is used to control the current direction and size of the motor.

[0027] As an embodiment, the voltage division sampling unit 20 comprises a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6 and a seventh resistor R7, one end of the first resistor R1 is connected to the first power terminal VD, the other end of the first resistor R1 is connected to one end of the third resistor R3 and has a first node A, the other end of the third resistor R3 is connected to one end of the direct current motor M, one end of the fifth resistor R5 is connected to one end of the direct current motor M, the other end of the fifth resistor R5 is connected to one end of the seventh resistor R7 and has a third node C, the other end of the seventh resistor R7 is grounded, one end of the second resistor R2 is connected to the first power terminal VD, the other end of the second resistor R2 is connected to one end of the fourth resistor R4 and has a second node B, the other end of the fourth resistor R4 is connected to the other end of the direct current motor M, one end of the sixth resistor R6 is connected to the other end of the direct current motor M, and the other end of the sixth resistor R6 is connected to the third node C.

[0028] As an embodiment, the first ADC port ADC1 of the microcontroller is connected to the first node A, the second ADC port ADC2 of the microcontroller is connected to the second node B, and the third ADC port ADC3 of the microcontroller is connected to the third node C.

[0029] It should be noted that when the first MOS tube Q1 and the fourth MOS tube Q4 are turned on, and the second MOS tube Q2 and the third MOS tube Q3 are turned off, the direct current motor rotates forward, and the voltage V M1 and V M2 can be calculated by the following formula:

[0030]

[0031] The voltage V M1 and V M2 can be calculated to obtain the voltage V M of the direct current motor:

[0032] V M = V M1 -V M2

[0033] In addition, V M2 is equal to the V DS voltage of the fourth MOS tube Q4, and the R DS(on) value of the fourth MOS tube Q4 can be obtained from the specification, and the current flowing through the fourth MOS tube Q4, that is, the direct current motor current I M is:

[0034]

[0035] In summary, the current flowing through the MOS tube can be calculated by measuring the voltage across the DC motor and combining the on-resistance of the MOS tube, and the current is the DC motor current; wherein the current flowing through the fourth MOS tube Q4 is calculated by measuring the drain-source voltage of the fourth MOS tube Q4 and combining the on-resistance of the fourth MOS tube Q4.

[0036] As an embodiment, the clamping protection unit 30 includes a first diode D1, a second diode D2 and a third diode D3, the negative electrode of the first diode D1 is connected to the second power supply end VC, the positive electrode of the first diode D1 is connected to the first node A, the negative electrode of the second diode D2 is connected to the second power supply end VC, the positive electrode of the second diode D2 is connected to the second node B, the negative electrode of the third diode D3 is connected to the second power supply end VC, and the positive electrode of the third diode D3 is connected to the third node C.

[0037] That is, the clamping protection unit 30 protects the ADC port by clamping diodes to prevent the DC motor voltage from damaging the ADC port of the microcontroller.

[0038] As an embodiment, a temperature sensor is further included, which is close to or arranged in the fourth MOS tube Q4 to monitor the junction temperature of the fourth MOS tube Q4.

[0039] That is, in order to improve the accuracy of current measurement, the temperature sensor is used to monitor the junction temperature of the fourth MOS tube, and the on-resistance is corrected according to the junction temperature, because the on-resistance of the fourth MOS tube is affected by temperature.

[0040] Specifically, as shown in Figures 3-4 , the R dS(on) value of the fourth MOS tube Q4 is basically not affected by the current size, but is affected by the working temperature, and a temperature sensor is added near or in the fourth MOS tube Q4 to monitor the junction temperature of the fourth MOS tube Q4, so as to correct the R DS(on) value, and the correction coefficient is K, so that the more accurate DC motor current can be obtained:

[0041]

[0042] Similarly, when the second MOS tube Q2 and the third MOS tube Q3 are turned on, and the first MOS tube Q1 and the fourth MOS tube Q4 are turned off, the DC motor is reversed, and the DC motor voltage V M and the DC motor current I M can also be calculated, and a temperature sensor is also arranged near or in the third MOS tube Q3 to monitor and supplement the third MOS tube Q3, so as to measure the DC motor current I M .

[0043] In summary, the current monitoring circuit of the H-bridge driving motor of the application is connected with the H-bridge driving unit through the voltage division sampling unit to divide the voltage at both ends of the DC motor, so that the voltage is controlled within the voltage range that can be sampled by the microcontroller; the clamping protection unit is connected with the voltage division sampling unit and the ADC port of the microcontroller to protect the ADC port of the microcontroller, so that the microcontroller can monitor the current of the DC motor through the ADC port, thereby, the on-resistance of the MOS tube of the H-bridge driving unit itself is used as the sampling current, and the voltage division sampling unit and the clamping protection unit are used to realize current monitoring, which is not only low in cost, but also good in monitoring effect.

[0044] In the description of the utility model, it is understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise" and the like are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the utility model and simplifying the description, and therefore cannot be understood as indicating or implying that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the utility model.

[0045] In addition, the terms "first" and "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first" and "second" can explicitly or implicitly include one or more of the features. In the description of the utility model, the meaning of "multiple" is two or more than two, unless otherwise specifically limited.

[0046] In the utility model, unless otherwise specifically defined and limited, the terms "mounting", "connection", "connection", "fixing" and the like should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication or interaction relationship between two elements. For ordinary skilled in the art, the specific meaning of the above terms in the utility model can be understood according to the specific circumstances.

[0047] In the present application, unless otherwise explicitly specified and limited, the first feature is "on" or "under" the second feature, which can include the first and second features directly contacting, or the first and second features not directly contacting but contacting through another feature between them. Moreover, the first feature "on", "above" and "on the surface" of the second feature includes the first feature directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature "under", "below" and "under" the second feature includes the first feature directly below and obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0048] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present application, the illustrative description of the above terms should not be understood as necessarily referring to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in the present application.

[0049] Although the embodiments of the present application have been shown and described above, it should be understood that the above embodiments are exemplary and cannot be understood as limiting the present application, and those skilled in the art can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A current monitoring circuit for an H-bridge driven motor, characterized in that, include: H-bridge drive unit, the H-bridge drive unit includes a DC motor; The voltage divider sampling unit is connected to the H-bridge drive unit to divide the voltage across the DC motor and control it within the voltage range that the microcontroller can sample. A clamping protection unit is connected to the voltage divider sampling unit and the ADC port of the microcontroller to protect the ADC port of the microcontroller, so that the microcontroller can monitor the current of the DC motor through the ADC port.

2. The current monitoring circuit for the H-bridge drive motor as described in claim 1, characterized in that, The H-bridge driving unit further includes a first MOS transistor, a second MOS transistor, a third MOS transistor, and a fourth MOS transistor. The drain of the first MOS transistor is connected to a voltage terminal, the source of the first MOS transistor is connected to the drain of the third MOS transistor, and the source of the third MOS transistor is grounded. The drain of the second MOS transistor is connected to the voltage terminal, the source of the second MOS transistor is connected to the drain of the fourth MOS transistor, and the source of the fourth MOS transistor is grounded.

3. The current monitoring circuit for the H-bridge drive motor as described in claim 2, characterized in that, One end of the DC motor is connected between the source of the first MOSFET and the drain of the third MOSFET, and the other end of the DC motor is connected between the source of the second MOSFET and the drain of the fourth MOSFET.

4. The current monitoring circuit for the H-bridge drive motor as described in claim 1, characterized in that, The voltage divider sampling unit includes a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, and a seventh resistor. One end of the first resistor is connected to a first power supply terminal. The other end of the first resistor is connected to one end of the third resistor and has a first node. The other end of the third resistor is connected to one end of the DC motor. One end of the fifth resistor is connected to one end of the DC motor. The other end of the fifth resistor is connected to one end of the seventh resistor and has a third node. The other end of the seventh resistor is grounded. One end of the second resistor is connected to the first power supply terminal. The other end of the second resistor is connected to one end of the fourth resistor and has a second node. The other end of the fourth resistor is connected to the other end of the DC motor. One end of the sixth resistor is connected to the other end of the DC motor and the other end of the sixth resistor is connected to the third node.

5. The current monitoring circuit for the H-bridge drive motor as described in claim 4, characterized in that, The microcontroller's first ADC port is connected to the first node, the microcontroller's second ADC port is connected to the second node, and the microcontroller's third ADC port is connected to the third node.

6. The current monitoring circuit for the H-bridge drive motor as described in claim 5, characterized in that, The clamping protection unit includes a first diode, a second diode, and a third diode. The negative terminal of the first diode is connected to a second power supply terminal, and the positive terminal of the first diode is connected to the first node. The negative terminal of the second diode is connected to the second power supply terminal, and the positive terminal of the second diode is connected to the second node. The negative terminal of the third diode is connected to the second power supply terminal, and the positive terminal of the third diode is connected to the third node.

7. The current monitoring circuit for the H-bridge drive motor as described in claim 3, characterized in that, It also includes a temperature sensor, which is located near or inside the fourth MOS transistor to monitor the junction temperature of the fourth MOS transistor.

8. The current monitoring circuit for the H-bridge drive motor as described in claim 3, characterized in that, It also includes a temperature sensor, which is located near or inside the third MOS transistor to monitor the junction temperature of the third MOS transistor.

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