A circuit board integrated in a motor back cover

Abstract

This application discloses a circuit board integrated within the rear cover of a motor, applicable to the field of electronic circuits. This circuit board integrates an electromagnetic compatibility (EMC) suppression circuit and a Hall sensor signal feedback circuit with memory function. The EMC suppression circuit, used to suppress electromagnetic interference from the motor, includes an EMC filter, a transient voltage suppression diode, a first filter capacitor, a second filter capacitor, and the motor itself. The Hall sensor signal feedback circuit includes a Hall sensor, a third filter capacitor, and a pull-up resistor. The Hall sensor is a bipolar latching type, used to output speed and position feedback signals based on the magnetic field of a bipolar magnetic ring mounted on the motor rotor. Thus, through the coordinated operation of the EMC filter, the transient voltage suppression diode, and multiple filter capacitors, the EMC of the motor is improved.

Description

Technical Field

[0001] This application relates to the field of electronic circuit technology, and in particular to a circuit board integrated into the rear cover of a motor. Background Technology

[0002] In high-frequency, high-density circuit environments, the commutation of the brushes in a DC brushed motor can easily generate strong electromagnetic interference. As DC brushed motors are increasingly widely used in fields with stringent requirements for reliability and electromagnetic compatibility, such as precision equipment, automotive electronics, and medical devices, higher demands are being placed on the electromagnetic compatibility (EMC) of these motors.

[0003] Currently, EMC is usually improved by means such as external shielding, independent filters or optimized grounding. However, these methods generally have drawbacks such as large size, high cost and complex structure, which make them difficult to implement in scenarios with limited space, such as the back cover of a micro motor.

[0004] Therefore, improving the electromagnetic compatibility of motors has become a problem that needs to be solved. Summary of the Invention

[0005] To address the aforementioned issues, this application provides a circuit board integrated within the motor's rear cover to improve the motor's electromagnetic compatibility.

[0006] The embodiments of this application disclose the following technical solutions: This application discloses a circuit board integrated in the rear cover of a motor, wherein the circuit board integrates an electromagnetic compatibility suppression circuit and a Hall sensor signal feedback circuit with memory function; The electromagnetic compatibility suppression circuit is used to suppress electromagnetic interference from the motor and includes: an electromagnetic interference filter, a transient voltage suppression diode, a first filter capacitor, a second filter capacitor, and the motor; a bipolar magnetic ring is installed on the motor rotor; One end of the electromagnetic interference filter is connected to both ends of the motor, and the other end is connected in parallel to both ends of the power supply; the transient voltage suppression diode is connected in parallel to both ends of the power supply; the first filter capacitor is connected between the first power input terminal and ground; the second filter capacitor is connected between the second power input terminal and ground. The Hall sensor signal feedback circuit includes a Hall sensor, a third filter capacitor, and a pull-up resistor. The Hall sensor is a bipolar latching Hall sensor, used to output speed and position feedback signals based on the magnetic field of the bipolar magnetic ring installed on the motor rotor. The output terminal and ground terminal of the Hall sensor are connected to the first power supply terminal, and the power supply terminal of the Hall sensor is connected to the second power supply terminal. The pull-up resistor is connected between the output terminal and the power supply terminal of the Hall sensor; The third filter capacitor is connected in parallel between the first power supply terminal and the second power supply terminal to filter out high-frequency ripple and spike noise on the power supply line.

[0007] Optionally, the electromagnetic interference filter includes a common-mode inductor and a differential-mode capacitor; wherein the common-mode inductor includes a first coil and a second coil with the same size and number of turns; One end of the first coil is connected to the first terminal of the differential-mode capacitor, and the other end is connected to the first terminal of the motor; one end of the second coil is connected to the second terminal of the differential-mode capacitor, and the other end is connected to the second terminal of the motor. The first end of the differential mode capacitor is connected to the first power input terminal of the circuit board, and the second end is connected to the second power input terminal of the circuit board.

[0008] Optionally, the electromagnetic compatibility suppression circuit further includes: one or more auxiliary filter capacitors; The auxiliary filter capacitor is connected in parallel across the motor.

[0009] Optionally, the Hall sensor signal feedback circuit further includes a decoupling capacitor; The decoupling capacitor is connected in parallel between the first power supply terminal and the second power supply terminal to filter out low- and medium-frequency power supply ripple; the capacitance of the decoupling capacitor is greater than the capacitance of the third filter capacitor.

[0010] Optionally, the Hall sensor signal feedback circuit further includes: a current-limiting resistor; One end of the current-limiting resistor is connected to the third filter capacitor, and the other end is connected to the decoupling capacitor.

[0011] Optionally, the Hall sensor signal feedback circuit further includes: a pull-down resistor; One end of the pull-down resistor is connected to the output terminal of the Hall sensor, and the other end is connected to the ground terminal of the Hall sensor.

[0012] Optionally, the Hall sensor signal feedback circuit further includes: a fifth filter capacitor; One end of the fifth filter capacitor is connected to the first power supply terminal, and the other end is connected to the output terminal of the Hall sensor.

[0013] Optionally, in the circuit board, the high-frequency signal traces adopt a microstrip line structure; the power supply traces adopt a star topology structure.

[0014] Optionally, in the circuit board, the signal lines of the Hall sensor are arranged using differential traces.

[0015] Optionally, the circuit board is soldered to the motor rear cover terminals via PIN holes.

[0016] Compared with the prior art, this application has the following beneficial effects: This application provides a circuit board integrated within the rear cover of a motor. This circuit board integrates an electromagnetic compatibility (EMC) suppression circuit and a Hall sensor signal feedback circuit with memory function. The EMC suppression circuit, used to suppress electromagnetic interference from the motor, includes: an EMC filter, a transient voltage suppression diode, a first filter capacitor, a second filter capacitor, and the motor itself. A bipolar magnetic ring is mounted on the motor rotor. One end of the EMC filter is connected to both ends of the motor, and the other end is connected in parallel to both ends of the power supply. The transient voltage suppression diode is connected in parallel to both ends of the power supply. The first filter capacitor is connected between the first power input terminal and ground. The second filter capacitor is connected between the second power input terminal and ground. The Hall sensor signal feedback circuit includes a Hall sensor, a third filter capacitor, and a pull-up resistor. The Hall sensor is a bipolar latching type Hall sensor used to output speed and position feedback signals based on the magnetic field of the bipolar magnetic ring mounted on the motor rotor. The output terminal and ground terminal of the Hall sensor are connected to the first power supply terminal, and the power supply terminal of the Hall sensor is connected to the second power supply terminal. The pull-up resistor is connected between the output terminal and the power supply terminal of the Hall sensor. The third filter capacitor is connected in parallel between the first and second power supply terminals to filter out high-frequency ripple and spike noise on the power supply line.

[0017] Therefore, on the one hand, through the coordinated operation of electromagnetic interference filters, transient voltage suppression diodes, and multiple filter capacitors, the spike voltage and high-frequency noise generated by motor commutation can be effectively absorbed, electromagnetic radiation and conducted interference during motor operation can be suppressed, the electromagnetic compatibility of the motor can be improved to meet relevant standard requirements, the impact of electromagnetic interference on the motor itself and surrounding electronic equipment can be reduced, and the stability of system operation can be improved. On the other hand, by integrating the electromagnetic compatibility suppression circuit and the Hall sensor signal feedback circuit into the motor rear cover, the integrated design of the motor body and the control circuit is realized. There is no need for an additional external feedback circuit and EMC suppression module, which greatly simplifies the wiring structure, reduces the assembly difficulty, reduces the space occupied, and adapts to the application requirements of miniaturized and lightweight motors. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of a circuit board integrated into the rear cover of a motor, as provided in an embodiment of this application. Detailed Implementation

[0020] The circuit board integrated into the motor rear cover provided in this application can be used in the field of electronic circuits. The above is only an example and does not limit the application field of the circuit board integrated into the motor rear cover provided in this application.

[0021] The terms "first," "second," "third," and "fourth," etc., used in this application specification, claims, and drawings are used to distinguish different objects, not to limit a specific order.

[0022] In the embodiments of this application, the terms "as an example" or "for example" are used to indicate that they are examples, illustrations, or explanations. Any embodiment or design that is described as "as an example" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design options. Specifically, the use of terms such as "as an example" or "for example" is intended to present the relevant concepts in a specific manner.

[0023] The terminology used in the implementation section of this application is for the purpose of explaining specific embodiments of this application only, and is not intended to limit this application.

[0024] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0025] See Figure 1 The figure is a schematic diagram of a circuit board integrated in the rear cover of a motor according to an embodiment of this application. The circuit board integrates an electromagnetic compatibility suppression circuit and a Hall sensor signal feedback circuit with memory function.

[0026] The electromagnetic compatibility suppression circuit and the Hall sensor signal feedback circuit can be integrated into the motor back cover using standard double-sided board technology and common EMC components. The layout is optimized for the limited space of the micro motor back cover, eliminating the need for external large filters or shielding covers. The structure is compact and requires no special materials or complex processes, making assembly simple and easy for automated mass production.

[0027] The electromagnetic compatibility (EMC) suppression circuit is used to suppress electromagnetic interference from the motor. It serves as the power supply and protection circuit for motor M, providing a stable and safe power source and filtering and protecting the motor. The EMC suppression circuit includes: an electromagnetic interference (EMI) filter, a transient voltage suppressor (TVS) diode, a first filter capacitor C1, a second filter capacitor C2, and motor M.

[0028] One end of the electromagnetic interference filter is connected to both ends of the motor M, and the other end is connected in parallel to both ends of the power supply.

[0029] Electromagnetic interference filters are used to perform bidirectional filtering of high-frequency electromagnetic interference generated by the operation of motor M, suppressing the interference from propagating outward along the power line.

[0030] Specifically, an electromagnetic interference filter includes a common-mode inductor and a differential-mode capacitor C.

[0031] The common-mode inductor includes a first coil L1 and a second coil L2 with the same size and number of turns. One end of the first coil L1 is connected to the first terminal of the differential-mode capacitor C, and the other end is connected to the first terminal of the motor M; one end of the second coil L2 is connected to the second terminal of the differential-mode capacitor C, and the other end is connected to the second terminal of the motor M.

[0032] The commutation of the motor's M brushes generates a large amount of high-frequency common-mode noise. The common-mode inductor presents high impedance to common-mode interference with the same phase and direction on the two power lines, which can effectively suppress the high-frequency noise generated by the brush commutation.

[0033] The first end of the differential mode capacitor C is connected to the first power input terminal PIN1 of the circuit board, and the second end is connected to the second power input terminal PIN3 of the circuit board.

[0034] The differential-mode capacitor C is connected in parallel between the positive and negative terminals of the power supply. It has low impedance to differential-mode interference in the form of opposite phase and voltage difference, which can be short-circuited and filtered out. This filters out high-frequency ripple on the power line, absorbs the reverse electromotive force and voltage spike generated when the motor M coil is de-energized, smooths the power supply waveform, provides a low-impedance path for high-frequency EMI, reduces EMI interference to external equipment, and improves conducted immunity.

[0035] The common-mode inductor and differential-mode capacitor C work together to form an electromagnetic interference filter, which can significantly widen the filtering frequency band and help the circuit pass the stringent EMC test.

[0036] The common-mode inductor, differential-mode capacitor C, first filter capacitor C1, and second filter capacitor C2 can also be used as a whole as an EMI filter network to suppress common-mode and differential-mode interference on the power line and prevent interference generated by the motor from flowing back into the power supply.

[0037] A transient voltage suppressor diode (TVS) is connected in parallel across the power supply.

[0038] TVS diodes can quickly clamp the reverse electromotive force and surge voltage generated by the commutation of motor M, absorb voltage spikes, and protect the subsequent circuits from overvoltage damage.

[0039] The first filter capacitor C1 is connected between the first power input terminal PIN1 and ground; the second filter capacitor C2 is connected between the second power input terminal PIN3 and ground. The first power input terminal PIN1 and the second power input terminal PIN3 are the power supply ports for the motor M.

[0040] The first filter capacitor C1 and the second filter capacitor C2 are both connected between the power supply and ground, providing a low-impedance return path for high-frequency interference noise, which can suppress common-mode interference, reduce electromagnetic interference, and further improve the filtering effect.

[0041] For example, the electromagnetic interference filter is positioned close to the connector on the circuit board to suppress interference at the input end, shorten the filtering path, and improve EMC suppression efficiency.

[0042] Optionally, the electromagnetic compatibility suppression circuit may also include one or more auxiliary filter capacitors C6 connected in parallel across the motor M to filter out high-frequency ripple generated during the operation of the motor M.

[0043] Optionally, the electromagnetic compatibility suppression circuit may also include a PTC thermistor, which is connected in series with the positive terminal of the power supply, for example, one end of which is connected to the first power input terminal PIN1 and the other end is connected to the first coil L1.

[0044] PCT thermistors are resettable fuses. When the circuit experiences overcurrent or overheating, the resistance of the PCT thermistor increases sharply, limiting the current and thus providing overcurrent protection for the circuit. Once the fault is cleared, the resistance of the PCT thermistor returns to a smaller value.

[0045] The electromagnetic compatibility suppression circuit provided in this application embodiment can significantly reduce electromagnetic noise conducted and radiated from the motor terminals, making it easier for the whole machine to meet EMC requirements such as FCC (Federal Communications Commission) and CE (Conformité Européenne).

[0046] The Hall sensor signal feedback circuit includes a Hall sensor, a third filter capacitor C3, and a pull-up resistor R1. It is a signal conditioning circuit for the Hall sensor used to detect the position of the rotor of motor M.

[0047] Specifically, the Hall sensor is a bipolar latching Hall sensor SC2442, used to output speed and position feedback signals based on the magnetic field of the bipolar magnetic ring mounted on the rotor of motor M.

[0048] Employing a bipolar latching Hall sensor, the speed and position feedback signals are output based on the magnetic field of the bipolar magnetic ring on the motor rotor. The bipolar latching characteristic ensures the stability of the signal output and avoids false triggering of the signal due to magnetic field fluctuations. At the same time, the circuit is integrated into the back cover, reducing the impact of external environmental interference on the feedback signal, improving the anti-interference capability of signal transmission, and providing accurate and reliable feedback for motor closed-loop control.

[0049] The Hall sensor's output terminal OUT and ground terminal GND are connected to the first power supply terminal PIN4, and the Hall sensor's power supply terminal VDD is connected to the second power supply terminal PIN2. The first power supply terminal PIN4 and the second power supply terminal PIN2 are the power supply input ports of the Hall sensor, where the first power supply terminal PIN4 is at ground potential.

[0050] A Hall sensor is positioned near the bipolar magnetic ring to sense the alternating magnetic field signal generated by the rotating motor rotor. When the south pole magnetic field strength of the bipolar magnetic ring reaches the trigger threshold B_OP, the Hall sensor outputs a low level; when the north pole magnetic field strength reaches the reset threshold B_RP, the Hall sensor outputs a high level; when the magnetic field of the bipolar magnetic ring disappears, the Hall sensor's output remains latched. Thus, for each rotation of one pole pair by the rotor of motor M, the Hall sensor outputs a complete square wave, providing accurate absolute position and rotational speed information.

[0051] Pull-up resistor R1 is connected between the output terminal OUT of the Hall sensor and the power supply terminal VDD. It can pull the output signal of the Hall sensor to the power supply level so as to form a standard high and low level digital signal, which is convenient for the controller to read.

[0052] As an example, the pull-up resistor R1 has a resistance of 3.9kΩ.

[0053] The third filter capacitor C3 is connected in parallel between the first power supply terminal PIN4 and the second power supply terminal PIN2. It is a power supply filter capacitor used to filter out high-frequency ripple and spike noise on the power supply line, providing a clean power supply for the Hall sensor.

[0054] As an example, the capacitance of the third filter capacitor C3 is 820pF.

[0055] The third filter capacitor C3 and the pull-up resistor R1 can form an RC low-pass filter to further attenuate the high-frequency noise coupled from the motor.

[0056] Optionally, the Hall sensor signal feedback circuit also includes a decoupling capacitor C4.

[0057] The decoupling capacitor C4 is connected in parallel between the first power supply terminal PIN4 and the second power supply terminal PIN2 of the Hall sensor to further filter out high-frequency interference and ensure the stability of the power supply to the Hall sensor.

[0058] The capacitance of decoupling capacitor C4 is greater than that of the third filter capacitor C3. For example, the capacitance of decoupling capacitor C4 can be 100nF.

[0059] Optionally, the Hall sensor signal feedback circuit also includes a current-limiting resistor R2.

[0060] One end of the current-limiting resistor R2 is connected to the third filter capacitor C3, and the other end is connected to the decoupling capacitor C4.

[0061] The current-limiting resistor R2 is used to limit the power supply current of the Hall sensor to prevent damage from overcurrent. At the same time, the current-limiting resistor R2, together with the third filter capacitor C3 and the decoupling capacitor C4, forms an RC filter network to further smooth the power supply voltage.

[0062] In one example, the current-limiting resistor R2 has a resistance of 100Ω.

[0063] Optionally, the Hall sensor signal feedback circuit also includes a pull-down resistor R3.

[0064] One end of the pull-down resistor R3 is connected to the output terminal OUT of the Hall sensor, and the other end is connected to the ground terminal GND of the Hall sensor.

[0065] The pull-down resistor R3 is a small-value pull-down resistor connected between the ground terminal GND and the output terminal OUT of the Hall sensor. It is used to define the low-level state of the output signal and stabilize the output signal so as to form a standard high and low level digital signal for easy reading by the controller.

[0066] In one example, the pull-down resistor R3 has a resistance of 10Ω.

[0067] Optionally, the Hall sensor signal feedback circuit also includes a fifth filter capacitor C5.

[0068] One end of the fifth filter capacitor C5 is connected to the first power supply terminal PIN4, and the other end is connected to the output terminal OUT of the Hall sensor.

[0069] The fifth filter capacitor C5 provides a high-frequency filtering path for the output signal of the Hall sensor, suppressing high-frequency glitches and ringing in the output signal, and absorbing interference noise on the signal line.

[0070] In this embodiment, on the one hand, through the coordinated operation of an electromagnetic interference filter, a transient voltage suppression diode, and multiple filter capacitors, the spike voltage and high-frequency noise generated by motor commutation can be effectively absorbed, and the electromagnetic radiation and conducted interference during motor operation can be suppressed, so that the electromagnetic compatibility of the motor meets the relevant standard requirements, reducing the impact of electromagnetic interference on the motor itself and surrounding electronic equipment, and improving the stability of system operation. On the other hand, by integrating the electromagnetic compatibility suppression circuit and the Hall sensor signal feedback circuit into the motor rear cover, the integrated design of the motor body and the control circuit is realized, eliminating the need for an additional external feedback circuit and EMC suppression module, greatly simplifying the wiring structure, reducing assembly difficulty, reducing space occupation, and adapting to the application requirements of miniaturized and lightweight motors.

[0071] This application embodiment, through a systematic circuit board design, enables the micro motor to meet EMC Level 5 standards in terms of radiated emissions, conducted emissions, and immunity, satisfying the requirements of high-reliability application scenarios. The resistor values ​​and capacitor values ​​provided in the above examples are only illustrative; in actual use, they can be adaptively adjusted according to the specific parameters of the micro DC motor or stepper motor.

[0072] In some embodiments provided in this application, the high-frequency signal traces in the circuit board adopt a microstrip line structure to control impedance matching.

[0073] In some embodiments provided in this application, the power traces in the circuit board adopt a star topology to reduce loop area.

[0074] In some embodiments provided in this application, sensitive signal lines such as the signal lines of Hall sensors in the circuit board are arranged differentially and kept away from power lines to suppress electromagnetic coupling and common-mode interference, improve the accuracy, stability and integrity of speed and position feedback signals, and improve the overall electromagnetic compatibility performance of the circuit.

[0075] The circuit board inside the motor's rear cover can be grounded to the motor's metal casing via a common-mode capacitor.

[0076] The circuit board is shaped to match the inner cavity of the motor's rear cover. The circuit board is soldered to the terminals of the rear cover through PIN holes. The interface and motor leads use soldered terminals, thereby improving assembly compactness and signal integrity.

[0077] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0078] The above description is merely one specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A circuit board integrated within the rear cover of a motor, characterized in that, The circuit board integrates an electromagnetic compatibility suppression circuit and a Hall sensor signal feedback circuit with memory function. The electromagnetic compatibility suppression circuit is used to suppress electromagnetic interference from the motor and includes: an electromagnetic interference filter, a transient voltage suppression diode, a first filter capacitor, a second filter capacitor, and the motor; a bipolar magnetic ring is installed on the motor rotor; One end of the electromagnetic interference filter is connected to both ends of the motor, and the other end is connected in parallel to both ends of the power supply; the transient voltage suppression diode is connected in parallel to both ends of the power supply; the first filter capacitor is connected between the first power input terminal and ground; the second filter capacitor is connected between the second power input terminal and ground. The Hall sensor signal feedback circuit includes a Hall sensor, a third filter capacitor, and a pull-up resistor. The Hall sensor is a bipolar latching Hall sensor, used to output speed and position feedback signals based on the magnetic field of the bipolar magnetic ring installed on the motor rotor. The output terminal and ground terminal of the Hall sensor are connected to the first power supply terminal, and the power supply terminal of the Hall sensor is connected to the second power supply terminal. The pull-up resistor is connected between the output terminal and the power supply terminal of the Hall sensor; The third filter capacitor is connected in parallel between the first power supply terminal and the second power supply terminal to filter out high-frequency ripple and spike noise on the power supply line.

2. The circuit board according to claim 1, characterized in that, The electromagnetic interference filter includes a common-mode inductor and a differential-mode capacitor; wherein the common-mode inductor includes a first coil and a second coil with the same size and number of turns; One end of the first coil is connected to the first terminal of the differential-mode capacitor, and the other end is connected to the first terminal of the motor; one end of the second coil is connected to the second terminal of the differential-mode capacitor, and the other end is connected to the second terminal of the motor. The first end of the differential mode capacitor is connected to the first power input terminal of the circuit board, and the second end is connected to the second power input terminal of the circuit board.

3. The circuit according to claim 1, characterized in that, The electromagnetic compatibility suppression circuit further includes: one or more auxiliary filter capacitors; The auxiliary filter capacitor is connected in parallel across the motor.

4. The circuit board according to claim 1, characterized in that, The Hall sensor signal feedback circuit also includes: a decoupling capacitor; The decoupling capacitor is connected in parallel between the first power supply terminal and the second power supply terminal to filter out low- and medium-frequency power supply ripple; the capacitance of the decoupling capacitor is greater than the capacitance of the third filter capacitor.

5. The circuit board according to claim 4, characterized in that, The Hall sensor signal feedback circuit further includes: a current-limiting resistor; One end of the current-limiting resistor is connected to the third filter capacitor, and the other end is connected to the decoupling capacitor.

6. The circuit board according to claim 1, characterized in that, The Hall sensor signal feedback circuit further includes: a pull-down resistor; One end of the pull-down resistor is connected to the output terminal of the Hall sensor, and the other end is connected to the ground terminal of the Hall sensor.

7. The circuit board according to claim 1, characterized in that, The Hall sensor signal feedback circuit also includes: a fifth filter capacitor; One end of the fifth filter capacitor is connected to the first power supply terminal, and the other end is connected to the output terminal of the Hall sensor.

8. The circuit board according to claim 1, characterized in that, In the circuit board, the high-frequency signal traces adopt a microstrip line structure; the power supply traces adopt a star topology structure.

9. The circuit board according to claim 1, characterized in that, In the circuit board, the signal lines of the Hall sensor are arranged differentially.

10. The circuit board according to claim 1, characterized in that, The circuit board is soldered to the motor rear cover terminals via PIN holes.

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