A current ripple detection circuit

Abstract

The utility model provides a kind of current ripple detection circuit, it is related to motor detection technical field, including: amplification comparison circuit, the amplification input end of amplification comparison circuit connects the current sampling end of motor;Current superposition circuit, the superposition current input end of current superposition circuit connects the amplification output end of amplification comparison circuit, the superposition current output end of current superposition circuit connects the first comparison input end of amplification comparison circuit, the stable current output end of current superposition circuit connects the second comparison input end of amplification comparison circuit;Square wave output circuit, the conduction output end of square wave output circuit connects the conduction output end of amplification comparison circuit, the square wave signal output end of square wave output circuit connects single-chip microcomputer.Affirmative effect is the ripple information of motor from starting, running to stop whole process can be detected;Without microprocessor and software data analysis;Scheme is simple, use material is conventional, quantity is less, and cost is low.

Description

Technical Field

[0001] This utility model relates to the field of motor testing technology, and in particular to a current ripple detection circuit. Background Technology

[0002] In the field of motor control, accurately detecting the position and speed of a brushed DC motor throughout its entire lifecycle—from start-up to operation and shutdown—is crucial, directly impacting the precision and efficiency of motor control. Currently, the industry primarily uses Hall effect sensors to achieve this. However, this approach requires a dedicated Hall effect detection module, which not only increases the motor's size but also raises material costs.

[0003] Besides Hall effect sensors, existing technologies also include detection schemes based on motor current ripple. These schemes attempt to infer the motor's position and speed by analyzing the ripple information in the motor current. However, existing ripple detection schemes have significant limitations. They typically can only detect ripple when the motor current is stable, while the accuracy and reliability of ripple detection decrease significantly, or even fail to detect it effectively, during motor startup and when the current changes.

[0004] Furthermore, existing ripple detection schemes heavily rely on microprocessors and complex software data analysis algorithms. This means that achieving effective ripple detection requires not only additional hardware costs (microprocessors) but also significant investment in software development and maintenance. This undoubtedly increases the complexity and cost of the entire detection system.

[0005] In summary, existing technologies for brushed DC motor position and speed detection, especially ripple-based detection schemes, suffer from limitations such as limited detection range, the need for additional hardware and software support, and high cost. These issues restrict the widespread application of ripple detection technology in brushed DC motor control, particularly in cost-sensitive and space-constrained applications. Therefore, developing a simple and cost-effective ripple detection technology capable of achieving full-process position and speed detection of brushed DC motors without microprocessors and software data analysis is of significant practical importance and application value. Utility Model Content

[0006] To address the problems existing in the prior art, this utility model provides a current ripple detection circuit, comprising:

[0007] An amplification and comparison circuit, wherein the amplification input terminal of the amplification and comparison circuit is connected to the current sampling terminal of the motor;

[0008] A current superposition circuit, wherein the superposition current input terminal of the current superposition circuit is connected to the amplification output terminal of the amplification and comparison circuit, the superposition current output terminal of the current superposition circuit is connected to the first comparison input terminal of the amplification and comparison circuit, and the stable current output terminal of the current superposition circuit is connected to the second comparison input terminal of the amplification and comparison circuit.

[0009] A square wave output circuit, wherein the conducting terminal of the square wave output circuit is connected to the conducting output terminal of the amplification and comparison circuit, and the square wave signal output terminal of the square wave output circuit is connected to a microcontroller.

[0010] Preferably, the amplification and comparison circuit includes an amplification and comparison chip, the positive terminal of which is connected to the operating voltage and is also connected to one end of a first capacitor and a second capacitor, the other ends of the first capacitor and the second capacitor are grounded, and the negative terminal of the amplification and comparison chip is grounded.

[0011] The amplification and comparison chip includes:

[0012] A first operational amplifier has its positive input terminal connected to the current sampling terminal, its inverting input terminal connected to one end of a first resistor and a second resistor, the other end of the first resistor being grounded, and the other end of the second resistor being connected to the output terminal of the first operational amplifier and the superimposed current input terminal of the current superposition circuit.

[0013] The second operational amplifier has its positive input terminal connected to the stable current output terminal of the current superposition circuit, its inverting input terminal connected to the superimposed current output terminal of the current superposition circuit, and its output terminal connected to the conduction terminal of the square wave output circuit.

[0014] Preferably, the current superposition circuit includes:

[0015] Superimposed current sub-circuits include:

[0016] The third resistor has one end connected to the first comparison input terminal of the amplification and comparison circuit and one end of the third capacitor. The other end of the third resistor is connected to one end of the fourth capacitor and one end of the fourth resistor. The other end of the fourth resistor is connected to the other end of the third capacitor and the reference voltage. The other end of the fourth capacitor is connected to the amplification output terminal of the amplification and comparison circuit.

[0017] The current-stabilizing sub-circuit includes:

[0018] The fifth resistor has one end connected to the second comparator input terminal of the amplification comparator circuit and one end of the fifth capacitor, and the other end of the fifth resistor is connected to one end of the sixth resistor. The other end of the sixth resistor is connected to the other end of the fifth capacitor and the reference voltage.

[0019] Preferably, it also includes an amplified current output circuit, comprising:

[0020] The seventh resistor has one end connected to the amplification output terminal of the amplification and comparison circuit, and the other end connected to one end of the sixth capacitor, one end of the eighth resistor, and the current sampling terminal of the microcontroller. The other ends of the sixth capacitor and the other ends of the eighth resistor are grounded.

[0021] Preferably, the square wave output circuit includes:

[0022] The ninth resistor has one end connected to the on output terminal of the amplification and comparison circuit, and the other end connected to one end of the tenth resistor and one end of the seventh capacitor. The other end of the tenth resistor and the other end of the seventh capacitor are grounded.

[0023] The NMOS transistor has its gate connected to the other end of the ninth resistor, its source grounded, its drain connected to one end of the eleventh resistor and the microcontroller, and the other end of the eleventh resistor connected to a square wave to provide voltage.

[0024] Preferably, the operating voltage is a DC voltage.

[0025] Preferably, the reference voltage is a DC voltage.

[0026] Preferably, the square wave provides a DC voltage.

[0027] The above technical solution has the following advantages or beneficial effects:

[0028] 1. It can detect ripple information of the motor throughout its entire life cycle, from startup and operation to shutdown. Through hardware circuitry, it directly amplifies, compares, and converts the current ripple, unrestricted by the motor's operating state, thus effectively capturing ripple information throughout the motor's entire lifecycle.

[0029] 2. No microprocessor or software data analysis required. Ripple detection and digital signal conversion are achieved based on hardware circuits, eliminating the cost and complexity of microprocessor and software development, significantly reducing system cost and development difficulty, and improving detection speed.

[0030] 3. The solution is simple, uses conventional materials in small quantities, and has low cost. The circuit structure is simple, using conventional operational amplifiers, resistors, capacitors, and MOSFETs, etc. The number of components is small, the solution is easy to implement, effectively reducing material and production costs, and also reducing the space occupied on the circuit board. Attached Figure Description

[0031] Figure 1The circuit principle of a current ripple detection circuit according to some embodiments of this application Figure 1 ;

[0032] Figure 2 The circuit principle of a current ripple detection circuit according to some embodiments of this application Figure 2 . Detailed Implementation

[0033] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The present invention is not limited to this embodiment; other embodiments that conform to the spirit of the present invention may also fall within its scope.

[0034] In a preferred embodiment of this utility model, based on the above-mentioned problems existing in the prior art, this utility model provides a current ripple detection circuit, such as... Figure 1 and Figure 2 As shown, it includes:

[0035] Amplification and comparison circuit 1, the amplification input terminal of amplification and comparison circuit 1 is connected to the current sampling terminal of the motor;

[0036] The superimposed current circuit 2 has its superimposed current input terminal connected to the amplification output terminal of the amplification and comparison circuit, its superimposed current output terminal connected to the first comparison input terminal of the amplification and comparison circuit, and its stable current output terminal connected to the second comparison input terminal of the amplification and comparison circuit.

[0037] Square wave output circuit 3, the conducting terminal of square wave output circuit 3 is connected to the conducting output terminal of amplifier comparator circuit, and the square wave signal output terminal of square wave output circuit is connected to microcontroller.

[0038] Specifically, the current ripple detection circuit provided by this utility model is based on the direct detection and conversion of the current ripple of a brushed DC motor through hardware circuitry, ultimately outputting a stable digital signal that can be recognized by a microcontroller. Its working principle can be broken down into the coordinated operation of the following three key circuit modules:

[0039] Amplification and Comparison Circuit 1: As the core processing unit of the circuit, this circuit first receives the signal from the motor current sampling terminal. Through an internal amplifier, the weak motor current signal is amplified, enhancing its driving capability and providing a clear signal foundation for subsequent processing. The amplified signal is then fed into the comparator module.

[0040] Current superposition circuit 2: This circuit is used for signal conditioning and reference voltage generation. It receives the amplified current signal from the amplifier-comparator circuit. This signal is mainly an AC ripple signal. The current superposition circuit superimposes this AC ripple signal with a stable 5V DC voltage signal. The superimposed signal is sent back to the first comparison input of the amplifier-comparator circuit, forming a fluctuating 5V signal. At the same time, the current superposition circuit also directly outputs a stable 5V DC voltage, which is connected to the second comparison input of the amplifier-comparator circuit as the reference voltage for comparison.

[0041] Square wave output circuit 3: This circuit serves as the final signal output interface, receiving the comparison result from the amplification and comparator circuit. The amplification and comparator circuit essentially functions as a comparator, comparing its first comparison input (a fluctuating 5V signal) with its second comparison input (a stable 5V reference voltage). When the voltage at the first comparison input is higher than that at the second comparison input, the comparator outputs a high level; otherwise, it outputs a low level. This generates a continuously alternating high and low level signal. The square wave output circuit further processes these level signals, including resistor voltage division and RC filtering, to enhance signal stability and anti-interference capabilities, ultimately converting the 12V high-level signal into a 5V high-level signal that is easier for the microcontroller to process, outputting a stable and reliable 5V square wave signal.

[0042] The beneficial effects of the motor ripple detection circuit in this embodiment are as follows:

[0043] 1. It can detect ripple information of the motor throughout the entire process from start-up, operation to shutdown.

[0044] Existing ripple detection solutions can only detect ripple when the motor current is stable, and cannot effectively detect ripple information during motor startup and current changes. This invention directly amplifies, compares, and converts current ripple through hardware circuitry, and is not limited by the motor's operating state, thus achieving effective capture of ripple information throughout the entire motor lifecycle.

[0045] 2. No microprocessor or software data analysis is required.

[0046] Existing ripple detection schemes heavily rely on microprocessors and complex software algorithms for data processing and analysis. This invention implements ripple detection and digital signal conversion entirely based on hardware circuits, eliminating the cost and complexity of microprocessor and software development, and significantly reducing system cost and development difficulty.

[0047] 3. The solution is simple, uses conventional materials, requires a small quantity, and has low cost.

[0048] Existing technologies, especially Hall sensor solutions, require independent detection modules, increasing material costs and motor space requirements. This invention features a simple circuit structure, employing conventional operational amplifiers, resistors, capacitors, and MOSFETs. With fewer components and a simpler implementation, it effectively reduces material and production costs while also minimizing circuit board space requirements.

[0049] In a preferred embodiment of this utility model, such as Figure 1 and Figure 2 As shown, the amplification and comparison circuit includes an amplification and comparison chip U1. The positive terminal of the amplification and comparison chip U1 is connected to the working voltage and is also connected to one end of the first capacitor C1 and the second capacitor C2. The other ends of the first capacitor and the second capacitor are grounded, and the negative terminal of the amplification and comparison chip is grounded.

[0050] The amplification and comparator chip U1 includes:

[0051] The first operational amplifier OP1 has its positive input terminal connected to the current sampling terminal IO, and its inverting input terminal connected to one end of the first resistor R1 and the second resistor R2. The other end of the first resistor R1 is grounded, and the other end of the second resistor R2 is connected to the output terminal of the first operational amplifier OP1 and the superimposed current input terminal of the current superposition circuit 2.

[0052] The second operational amplifier OP2 has its positive input terminal connected to the stable current output terminal of the current superposition circuit 2, its inverting input terminal connected to the superimposed current output terminal of the current superposition circuit 2, and its output terminal connected to the conduction terminal of the square wave output circuit 3.

[0053] Preferably, the operating voltage is 12V DC.

[0054] Specifically, the functions of each electronic component in this embodiment are as follows:

[0055] For the amplifier / comparator chip U1 (such as a dual op-amp IC): its positive terminal (Vcc) is connected to the operating voltage (such as 12V) to power the entire chip. The negative terminal (GND) is grounded, forming a complete circuit loop.

[0056] The first capacitor (C1) and the second capacitor (C2): one end is connected to Vcc and the other end is grounded, forming a power supply decoupling circuit. Its function is to filter out high-frequency noise from the power supply, ensure the stable operating voltage of the op-amp, and avoid introducing interference when amplifying signals.

[0057] For the first operational amplifier OP1 (signal amplification unit): its positive input terminal (+) is directly connected to the current sampling terminal (i.e., the voltage signal IO of the motor current sampling resistor). The inverting input terminal (-) is connected to one end of the first resistor (R1) and the second resistor (R2), forming an inverting amplification structure.

[0058] The other end of the first resistor (R1) is grounded, and together with R2, it sets the amplification gain (gain formula: Gain = -R2 / R1). The other end of the second resistor (R2) is connected to the output terminal of the first operational amplifier OP1, serving as a feedback resistor to feed the amplified signal back to the inverting input terminal.

[0059] The output terminal is connected to the superimposed current input terminal of the current superposition circuit 2.

[0060] Its function is to amplify the weak voltage signal (such as a mV-level signal on a 0.1Ω resistor) of the sampling resistor IO by a ratio of R2 / R1 (e.g., amplify it by 100 times). The output is an amplified DC voltage signal with ripple (e.g., 0-0.5V amplified to 0-50V, the actual output amplitude after power clamping is limited by the supply voltage).

[0061] For the second operational amplifier OP2 (signal comparator unit): its positive input terminal (+) is connected to the stable current output terminal of the current superposition circuit 2 (i.e., a stable 5V reference voltage). Its inverting input terminal (-) is connected to the superimposed current output terminal of the current superposition circuit 2 (i.e., a fluctuating 5V signal superimposed with the ripple AC signal).

[0062] Output terminal: Connect to the on terminal of the square wave output circuit 3 (such as the gate of a MOS transistor).

[0063] Its function is to compare a stable 5V reference voltage (non-inverting input) with a fluctuating 5V signal (inverting input) in real time. When the fluctuating signal > 5V, it outputs a low level (0V); when the fluctuating signal < 5V, it outputs a high level (e.g., 12V). It converts the ripple signal into a square wave with alternating high and low levels (the frequency is consistent with the motor commutation ripple).

[0064] The overall workflow of the amplification and comparison circuit in this embodiment includes:

[0065] 1. Signal amplification

[0066] Sampling resistor voltage → amplified by the first operational amplifier (gain set by R1 / R2) → outputs amplified ripple signal.

[0067] 2. Signal Comparison

[0068] The amplified ripple signal is coupled into a fluctuating 5V signal through a current superposition circuit and then input to the inverting input of the second operational amplifier.

[0069] A stable 5V reference voltage is input to the non-inverting input of the second operational amplifier → a square wave is output through voltage comparison.

[0070] 3. Output control

[0071] The square wave signal drives subsequent circuits (such as MOSFETs) and is converted into a 5V square wave output to the microcontroller.

[0072] The key design considerations for the amplification and comparison circuit in this embodiment are:

[0073] The dual op-amp integrated design uses a single chip to integrate two op-amps (such as the LM358), saving space and ensuring that both op-amps operate under identical conditions. The decoupling capacitors (C1 / C2) eliminate power supply noise, preventing signal distortion or comparator mis-triggers. The amplification resistor network (R1 / R2) ensures that weak ripple signals are effectively amplified to a suitable amplitude for comparison by precisely setting the gain. The second op-amp operates in open-loop mode (without feedback resistors) as a zero-crossing comparator, achieving efficient conversion from analog signals to digital square waves.

[0074] Achieve MCU-free operation: The ripple to square wave conversion is completed directly through hardware circuitry (op-amp + comparator), without the need for software analysis.

[0075] Capable of full-process detection: The comparator has an extremely fast response speed (microsecond level) and can capture transient ripples when the motor starts / stops.

[0076] It also has the advantage of low cost: it only requires conventional resistors, capacitors, and dual operational amplifier chips, and the material cost is significantly lower than that of Hall sensor solutions.

[0077] This design achieves a fully hardware-based conversion of motor ripple to digital square wave through cascaded processing of the hardware signal chain (amplification → superposition → comparison → level conversion).

[0078] In a preferred embodiment of this utility model, such as Figure 1 and Figure 2 As shown, the current superposition circuit 2 includes:

[0079] Superimposed current sub-circuits include:

[0080] The third resistor R3 is connected to the first comparison input terminal of the amplification and comparison circuit 1 and one end of the third capacitor C3. The other end of the third resistor R3 is connected to one end of the fourth capacitor C4 and one end of the fourth resistor R4. The other end of the fourth resistor R4 is connected to the other end of the third capacitor C3 and the reference voltage 5V. The other end of the fourth capacitor C4 is connected to the amplification output terminal of the amplification and comparison circuit 1.

[0081] The current-stabilizing sub-circuit includes:

[0082] The fifth resistor R5 is connected to the second comparator input terminal of the amplifier comparator circuit 1 and one end of the fifth capacitor C5. The other end of the fifth resistor R5 is connected to one end of the sixth resistor R6. The other end of the sixth resistor R6 is connected to the other end of the fifth capacitor C5 and the reference voltage 5V.

[0083] Preferably, the reference voltage is a 5V DC voltage.

[0084] Specifically, the current superposition circuit design in this embodiment realizes the two core functions of ripple AC coupling and stable reference voltage generation in the technical principle. The following is a functional analysis of each component and the logic for achieving the technical effect:

[0085] For superimposed current sub-circuits:

[0086] The third resistor (R3) is connected to the first comparator input terminal at one end and to the fourth capacitor (C4) at the other end. Its function is current limiting protection: to prevent the coupling capacitor C4 from being damaged by excessive instantaneous charging and discharging current.

[0087] The fourth capacitor (C4) is connected to R3 at one end and to the amplification output terminal (output of the first operational amplifier) ​​at the other end. Its function is AC coupling: to block the DC component in the amplified signal and only allow the ripple AC signal to pass through (key technical point).

[0088] The third capacitor (C3) is connected at one end to the intersection of R3 and the first comparison input terminal, and at the other end to the reference voltage (5V). Its function is high-frequency filtering: filtering out high-frequency noise in the ripple to ensure signal purity.

[0089] The fourth resistor (R4) is connected at one end to the intersection of R3 and C4, and at the other end to the reference voltage (5V). Its function is DC bias: to provide a 5V DC bias for the AC ripple signal, forming a "fluctuating 5V signal".

[0090] The workflow is as follows: amplified ripple signal (including DC component) → DC blocking by C4 → pure AC ripple → current limiting by R3 → 5V DC bias superimposed by R4 → output ripple signal with 5V as reference to the first comparison input terminal.

[0091] For steady current sub-circuits:

[0092] The fifth resistor (R5) is connected to the second comparator input terminal at one end and to the sixth resistor (R6) at the other end. Its function is as a voltage divider resistor: together with R6, it forms a voltage divider network to stably transmit the reference voltage (5V) to the second comparator input terminal.

[0093] The sixth resistor (R6) is connected to R5 at one end and to the reference voltage (5V) at the other end. Its function is as a voltage divider resistor: the voltage division ratio is fixed (if R5 = R6, the output is 2.5V; the resistance value needs to be adjusted according to the comparison threshold).

[0094] The fifth capacitor (C5) is connected to the second comparator input terminal on one end and to the reference voltage (5V) on the other end. Its function is to stabilize the voltage: filter out high-frequency noise of the reference voltage and ensure that the comparator reference voltage is absolutely stable (key design).

[0095] The workflow is as follows: reference voltage (5V) → voltage divider R5-R6 → generating a stable reference voltage (e.g., 2.5V) → filter C5 → output to the second comparator input.

[0096] In a preferred embodiment of this utility model, an amplified current output circuit 4 is also included, such as... Figure 1 and Figure 2 As shown, it includes:

[0097] The seventh resistor R7 has one end connected to the amplification output terminal of the amplification and comparator circuit, and the other end connected to one end of the sixth capacitor C6, one end of the eighth resistor R8, and the current sampling terminal IAD of the microcontroller. The other ends of the sixth capacitor C6 and the other ends of the eighth resistor R8 are grounded.

[0098] Specifically, this embodiment also includes an amplified current output circuit 4, which can directly output the amplified motor ripple signal to the microcontroller, providing more data information for data processing in the microcontroller.

[0099] In a preferred embodiment of this utility model, such as Figure 1 and Figure 2 As shown, the square wave output circuit 3 includes:

[0100] The ninth resistor R9 has one end connected to the on output terminal of the amplifier comparator circuit 1, and the other end connected to one end of the tenth resistor R10 and one end of the seventh capacitor C7. The other ends of the tenth resistor R10 and the seventh capacitor C7 are grounded.

[0101] NMOS transistor Q1 has its gate connected to the other end of resistor R9 (the ninth resistor), its source grounded, and its drain connected to one end of resistor R11 (the eleventh resistor) and the microcontroller PIN. The other end of resistor R11 is connected to a square wave to provide voltage.

[0102] Preferably, the square wave provides a 5V DC voltage.

[0103] Specifically, in this embodiment, one end of the ninth resistor (R9) is connected to the on output terminal (second operational amplifier output) of the amplification and comparator circuit, and the other end is connected to R10, C7 and the NMOS gate. Its function is to limit the gate current and match the impedance, thereby limiting the charging current of the NMOS gate, preventing the comparator from overloaded and suppressing high-frequency oscillation.

[0104] The tenth resistor (R10) is connected at one end to the intersection of R9 and the NMOS gate, and the other end is grounded. Its function is to act as a gate pull-down resistor to quickly release the gate charge, accelerate the NMOS turn-off, and prevent false triggering due to gate floating.

[0105] The seventh capacitor (C7) is connected at one end to the intersection of R9 and the NMOS gate, and the other end is grounded. Its function is to filter high-frequency noise, filter out high-frequency glitches (such as ringing noise) in the comparator output, and ensure the purity of the square wave signal.

[0106] The gate of the NMOS transistor (Q1) is connected to the intersection of R9 / R10 / C7, the source is grounded, and the drain is connected to R11 and the microcontroller. Its function is level conversion and driving, converting the high level (12V) output of the comparator into a 5V square wave, enhancing the load capacity and protecting the microcontroller pins.

[0107] One end of resistor (R11) is connected to a square wave to provide voltage (5V), and the other end is connected to the drain of the NMOS and the microcontroller. Its function is to act as a pull-up resistor and current limiter. When the NMOS is turned off, it provides a 5V high level to the microcontroller and limits the current when the NMOS is turned on.

[0108] The technical principle and implementation logic of the square wave output circuit include:

[0109] Signal conversion process:

[0110] The input signal source is the high and low level square wave output of the second operational amplifier (e.g., low level 0V, high level 12V).

[0111] Signal conditioning and conversion:

[0112] R9-R10 voltage divider: reduces the 12V high level output of the comparator to a voltage suitable for NMOS drive (e.g., 10V): VGS = Vin × (R10 / (R9 + R10)); C7 filter: absorbs gate transient spikes (e.g., noise >10MHz) to prevent NMOS malfunction.

[0113] NMOS switch operation:

[0114] When the comparator outputs a high level (12V) → the NMOS is turned on → the drain is pulled low to 0V (ground);

[0115] When the comparator outputs a low level (0V), the NMOS is turned off, and R11 pulls the drain up to 5V.

[0116] Output signal: generates a square wave of 0V (low) / 5V (high) and directly inputs it into the microcontroller.

[0117] Therefore, this circuit achieves safe voltage reduction through a three-stage structure of "gate drive conditioning (R9 / R10 / C7) + NMOS switch (Q1) + pull-up output (R11)": safely driving the NMOS with the output of the 12V comparator; filtering out noise and eliminating ringing; and outputting a 0V / 5V square wave to the microcontroller.

[0118] Ultimately, it achieves a stable conversion from "high voltage to safe logic level, analog ripple to digital square wave" at extremely low cost; the response speed of the entire hardware link is significantly improved compared to the MCU solution, and it perfectly supports transient detection of motor start and stop.

[0119] The above are merely preferred embodiments of the present utility model and are not intended to limit the implementation methods and protection scope of the present utility model. Those skilled in the art should realize that any equivalent substitutions and obvious changes made using the content of this specification and illustrations should be included within the protection scope of the present utility model.

Claims

1. A current ripple detection circuit, characterized in that, include: An amplification and comparison circuit, wherein the amplification input terminal of the amplification and comparison circuit is connected to the current sampling terminal of the motor; A current superposition circuit, wherein the superposition current input terminal of the current superposition circuit is connected to the amplification output terminal of the amplification and comparison circuit, the superposition current output terminal of the current superposition circuit is connected to the first comparison input terminal of the amplification and comparison circuit, and the stable current output terminal of the current superposition circuit is connected to the second comparison input terminal of the amplification and comparison circuit. A square wave output circuit, wherein the conducting terminal of the square wave output circuit is connected to the conducting output terminal of the amplification and comparison circuit, and the square wave signal output terminal of the square wave output circuit is connected to a microcontroller.

2. The current ripple detection circuit according to claim 1, characterized in that, The amplification and comparison circuit includes an amplification and comparison chip. The positive terminal of the amplification and comparison chip is connected to the operating voltage and is also connected to one end of a first capacitor and a second capacitor. The other ends of the first capacitor and the second capacitor are grounded, and the negative terminal of the amplification and comparison chip is grounded. The amplification and comparison chip includes: A first operational amplifier has its positive input terminal connected to the current sampling terminal, its inverting input terminal connected to one end of a first resistor and a second resistor, the other end of the first resistor being grounded, and the other end of the second resistor being connected to the output terminal of the first operational amplifier and the superimposed current input terminal of the current superposition circuit. The second operational amplifier has its positive input terminal connected to the stable current output terminal of the current superposition circuit, its inverting input terminal connected to the superimposed current output terminal of the current superposition circuit, and its output terminal connected to the conduction terminal of the square wave output circuit.

3. The current ripple detection circuit according to claim 1, characterized in that, The current superposition circuit includes: Superimposed current sub-circuits include: The third resistor has one end connected to the first comparison input terminal of the amplification and comparison circuit and one end of the third capacitor. The other end of the third resistor is connected to one end of the fourth capacitor and one end of the fourth resistor. The other end of the fourth resistor is connected to the other end of the third capacitor and the reference voltage. The other end of the fourth capacitor is connected to the amplification output terminal of the amplification and comparison circuit. The current-stabilizing sub-circuit includes: The fifth resistor has one end connected to the second comparator input terminal of the amplification comparator circuit and one end of the fifth capacitor, and the other end of the fifth resistor is connected to one end of the sixth resistor. The other end of the sixth resistor is connected to the other end of the fifth capacitor and the reference voltage.

4. The current ripple detection circuit according to claim 1, characterized in that, It also includes a current amplification output circuit, including: The seventh resistor has one end connected to the amplification output terminal of the amplification and comparison circuit, and the other end connected to one end of the sixth capacitor, one end of the eighth resistor, and the current sampling terminal of the microcontroller. The other ends of the sixth capacitor and the other ends of the eighth resistor are grounded.

5. The current ripple detection circuit according to claim 1, characterized in that, The square wave output circuit includes: The ninth resistor has one end connected to the on output terminal of the amplification and comparison circuit, and the other end connected to one end of the tenth resistor and one end of the seventh capacitor. The other end of the tenth resistor and the other end of the seventh capacitor are grounded. The NMOS transistor has its gate connected to the other end of the ninth resistor, its source grounded, its drain connected to one end of the eleventh resistor and the microcontroller, and the other end of the eleventh resistor connected to a square wave to provide voltage.

6. The current ripple detection circuit according to claim 2, characterized in that, The operating voltage is a DC voltage.

7. The current ripple detection circuit according to claim 3, characterized in that, The reference voltage is a DC voltage.

8. The current ripple detection circuit according to claim 6, characterized in that, The square wave provides a DC voltage.

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