EMC discrete noise compensation circuit and method

Abstract

The invention relates to an EMC discrete noise compensation circuit, and the circuit comprises a noise generation module which is used for generating a square signal and a gain adjustment signal based on a discrete noise signal, and the square signal and the discrete noise signal are the same in frequency and are opposite in phase; the gain amplification module is used for generating a noise compensation signal which counteracts the discrete noise signal based on the square wave signal and the gain adjustment signal; and the signal coupling module is used for coupling the noise compensation signal to an EMC (Electro Magnetic Compatibility) port of the electronic equipment so as to offset the discrete noise signal. According to the method, a specific noise source is introduced innovatively, the effect of totally compensating and counteracting the excessive noise signal is achieved by coupling the inverted same frequency noise signal and the original noise signal, various complex combination attempts such as filtering, suppression, bypass, shielding and grounding of traditional measures are abandoned, and the method is simple, clear and easy to implement.

Description

Technical Field

[0001] The present invention relates to the field of electromagnetic compatibility (EMC), and more specifically, to an EMC discrete noise compensation circuit and method. Background Art

[0002] With the application of various electronic devices, the EMC issues between electronic devices have become more and more complicated, and at the same time, they have received more and more attention. Various countries have introduced EMC mandatory standards. If the product fails to pass the EMC test, it will not be able to enter the market smoothly. Therefore, the analysis and rectification of electromagnetic compatibility of products is particularly important.

[0003] Conventional EMC rectification measures usually include: 1. Eliminate various noise sources as much as possible; 2. Suppress EMC noise signals at the same time. However, when encountering particularly stubborn noise, especially when the noise is unavoidable and has a few discrete frequency points, it is very difficult and time-consuming to use traditional methods. Summary of the invention

[0004] The technical problem to be solved by the present invention is that, in view of the above-mentioned defects of the prior art, a method is provided for discrete excessive noise signals, a specific noise source is innovatively introduced, and an inverse frequency noise signal is coupled with the original noise signal to achieve the effect of overall compensation to offset the excessive noise signal.

[0005] The technical solution adopted by the present invention to solve the technical problem is: constructing an EMC discrete noise compensation circuit, including:

[0006] A noise generating module, used to generate a square wave signal and a gain adjustment signal based on a discrete noise signal, wherein the frequency of the square wave signal is the same as that of the discrete noise signal and the phase is opposite;

[0007] a gain amplification module, configured to generate a noise compensation signal that cancels out the discrete noise signal based on the square wave signal and the gain adjustment signal; and

[0008] A signal coupling module, used for coupling the noise compensation signal to an EMC port of an electronic device to offset the discrete noise signal;

[0009] The gain amplification module includes a comparator unit and an adjustable power supply unit;

[0010] The adjustable power supply unit is used to receive the gain adjustment signal and generate a voltage adjustment signal based on the gain adjustment signal;

[0011] The comparator unit is used to receive the square wave signal and the voltage adjustment signal, and adjust the amplitude of the square wave signal based on the voltage adjustment signal to obtain the noise compensation signal; the noise compensation signal has the same frequency and amplitude as the discrete noise signal and an opposite phase.

[0012] In the EMC discrete noise compensation circuit of the present invention, the noise generation module includes:

[0013] The MCU unit is used to generate n square wave signals and n gain adjustment signals corresponding to each other based on n discrete noise signals; wherein n is a positive integer.

[0014] In the EMC discrete noise compensation circuit of the present invention, the comparator unit includes n comparators, and the adjustable power supply unit includes n adjustable voltage branches;

[0015] The first input end of each adjustable voltage branch is connected to the power supply voltage, the second end receives a gain adjustment signal, and the output end outputs a corresponding voltage adjustment signal;

[0016] The positive input terminal and the negative input terminal of each comparator receive a square wave signal, the positive pole of the power supply receives a corresponding voltage regulation signal, the negative pole of the power supply is grounded, and the output terminal outputs a corresponding noise compensation signal.

[0017] In the EMC discrete noise compensation circuit of the present invention, the adjustable voltage branch includes a switch tube, a diode and a capacitor;

[0018] The collector of the switch tube is connected to the first input end of the adjustable voltage branch, the gate is connected to the second end of the adjustable voltage branch, and the emitter is the output end of the adjustable voltage branch; the cathode of the diode and the first end of the capacitor are connected to the emitter of the switch tube, and the anode of the diode and the second end of the capacitor are grounded.

[0019] In the EMC discrete noise compensation circuit described in the present invention, the signal coupling module includes n coupling units, a first end of each coupling unit is connected to an output end of a comparator to receive a corresponding noise compensation signal, and a second end is connected to an L line or an N line of the EMC port of the electronic device.

[0020] In the EMC discrete noise compensation circuit of the present invention, the coupling unit includes a Y capacitor.

[0021] The EMC discrete noise compensation circuit of the present invention further includes a fine-tuning module, which is used to reacquire the discrete noise signal after the cancellation is completed, compare the reacquired discrete noise signal with the expected value, and fine-tune the square wave signal and / or the gain adjustment signal corresponding to the discrete noise signal based on the comparison result, thereby fine-tuning the frequency and / or amplitude of the corresponding noise compensation signal.

[0022] Another technical solution adopted by the present invention to solve the technical problem is to construct an EMC discrete noise compensation method, which is applied to the aforementioned EMC discrete noise compensation circuit, comprising the following steps:

[0023] S1, generating a set of square wave signals and gain adjustment signals based on each discrete noise signal in a one-to-one correspondence, wherein the frequency of each square wave signal is the same as the frequency of the corresponding discrete noise signal and the phase is opposite;

[0024] S2, generating a noise compensation signal based on each set of square wave signals and gain adjustment signals to cancel out the corresponding discrete noise signal, wherein each noise compensation signal has the same frequency and amplitude as its corresponding discrete noise signal and has an opposite phase;

[0025] S3. Coupling the noise compensation signal to an EMC port of an electronic device to offset the corresponding discrete noise signal.

[0026] The EMC discrete noise compensation method of the present invention further comprises the following steps:

[0027] S4. After the cancellation is completed, the discrete noise signal is reacquired, and the reacquired discrete noise signal is compared with the expected value, and the square wave signal and / or the gain adjustment signal corresponding to the discrete noise signal are fine-tuned based on the comparison result, thereby fine-tuning the frequency and / or amplitude of the corresponding noise compensation signal.

[0028] In the EMC discrete noise compensation method of the present invention, the frequency of the discrete noise signal is less than 20 MHz.

[0029] The EMC discrete noise compensation circuit and method of the present invention innovatively introduces a specific noise source, and couples the anti-phase frequency noise signal with the original noise signal to achieve the effect of overall compensation to offset the excessive noise signal, abandoning various complex combination attempts of traditional measures such as filtering, suppression, bypassing, shielding, grounding, etc. The method is simple, clear and easy to implement. Furthermore, discrete noise signals of multiple isolated excessive frequency points can be compensated simultaneously. Furthermore, based on the actual discrete noise signal, the frequency and amplitude of the corresponding noise compensation signal can be flexibly and adaptively adjusted, which is suitable for scenarios where discrete noise changes at any time. Furthermore, active feedback adjustment can be achieved by collecting the offset discrete noise signal and feedback-adjusting the frequency and amplitude of the noise compensation signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0031] Figure 1 It is a principle block diagram of a preferred embodiment of the EMC discrete noise compensation circuit of the present invention;

[0032] Figure 2 is a circuit diagram of a preferred embodiment of the EMC discrete noise compensation circuit of the present invention;

[0033] Figure 3 This is an example of measured EMC data of electronic equipment when EMC compensation is not performed;

[0034] Figure 4 This is an example of measured EMC data of an electronic device after EMC compensation using the EMC discrete noise compensation circuit of the present invention;

[0035] Figure 5 It is a flow chart of the EMC discrete noise compensation method described in the present invention. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0037] The present invention relates to an EMC discrete noise compensation circuit, comprising: a noise generating module, used for generating a square wave signal and a gain adjustment signal based on a discrete noise signal, the frequency of the square wave signal being the same as the frequency of the discrete noise signal and having an opposite phase; a gain amplifying module, used for generating a noise compensation signal that cancels out the discrete noise signal based on the square wave signal and the gain adjustment signal; and a signal coupling module, used for coupling the noise compensation signal to an EMC port of an electronic device to cancel out the discrete noise signal; the gain amplifying module comprises a comparator unit and an adjustable power supply unit; the adjustable power supply unit is used for receiving the gain adjustment signal and generating a voltage adjustment signal based on the gain adjustment signal; the comparator unit is used for receiving the square wave signal and the voltage adjustment signal, and adjusting the amplitude of the square wave signal based on the voltage adjustment signal to obtain the noise compensation signal; the noise compensation signal is the same as the frequency and amplitude of the discrete noise signal and has an opposite phase. The EMC discrete noise compensation circuit and method of the present invention innovatively introduces a specific noise source, and couples the anti-phase frequency noise signal with the original noise signal to achieve the effect of overall compensation to offset the excessive noise signal, abandoning various complex combination attempts of traditional measures such as filtering, suppression, bypassing, shielding, grounding, etc. The method is simple, clear and easy to implement.

[0038] The EMC discrete noise compensation circuit of the present invention, for some isolated and discrete discrete noise signals of over-standard frequency points, abandons the method of eliminating the noise source, and abandons various complex combination attempts of traditional measures such as filtering, suppression, bypassing, shielding, grounding, etc., and specially introduces or creates a specific new noise source; this noise source combines the characteristics of over-standard noise and can be applied to any frequency point, and through reverse output, it is coupled with the original noise to achieve the effect of overall offsetting the over-standard noise. It is especially suitable for the presence of multiple discrete and changing over-standard frequency points.

[0039] Figure 1 1 is a principle block diagram of a preferred embodiment of the EMC discrete noise compensation circuit of the present invention. Figure 1 As shown, the EMC discrete noise compensation circuit includes: a noise generation module 100, a gain amplification module 200 and a signal coupling module 300. Figure 1 As shown, the noise generating module 100 is used to generate a square wave signal and a gain adjustment signal based on a discrete noise signal, respectively. The frequency of the square wave signal is the same as the frequency of the discrete noise signal and the phase is opposite. The gain amplifying module 200 is used to generate a noise compensation signal that cancels out the discrete noise signal based on the square wave signal and the gain adjustment signal. The signal coupling module 300 is used to couple the noise compensation signal to the EMC port 400 of the electronic device to cancel out the discrete noise signal.

[0040] Preferably, in a preferred embodiment of the present invention, the noise generation module can be composed of any MCU module, which can be used to receive n discrete noise signals of the electronic device input by the user, and then generate a set of corresponding square wave signals and gain adjustment signals based on each discrete noise signal. Preferably, in another preferred embodiment of the present invention, the noise generation module can be composed of any MCU module equipped with a noise signal acquisition function, which can be used to collect n discrete noise signals of the electronic device, and then generate a set of corresponding square wave signals and gain adjustment signals based on each discrete noise signal, and the frequency of each square wave signal is the same as the frequency of the corresponding discrete noise signal and the phase is opposite. The gain adjustment signal can be determined according to the amplitude of the square wave signal and the amplitude of the discrete noise signal. For example, in the case where the amplitude of the square wave signal is fixed, the gain adjustment signal can be determined according to the amplitude of the discrete noise signal. When the amplitude of the square wave signal is adjustable, the gain adjustment signal can be determined according to the amplitude of the discrete noise signal and the amplitude of the selected square wave signal. Here, as long as it is ensured that the frequency of each square wave signal is the same as the frequency of the corresponding discrete noise signal and the phase is opposite, the amplitude of the square wave signal and the gain adjustment signal can be adjusted according to actual conditions.

[0041] Preferably, in a preferred embodiment of the present invention, the gain amplification module 200 includes a comparator unit 210 and an adjustable power supply unit 220. The adjustable power supply unit 220 is used to receive the gain adjustment signal and generate a voltage adjustment signal based on the gain adjustment signal. The comparator unit 210 is used to receive the square wave signal and the voltage adjustment signal, and adjust the amplitude of the square wave signal based on the voltage adjustment signal to obtain the noise compensation signal; the noise compensation signal has the same frequency and amplitude as the discrete noise signal and an opposite phase. Here, any suitable comparator and adjustable power supply can be used, as long as it can adjust the amplitude of the square wave signal based on the gain adjustment signal to generate the noise compensation signal with the same frequency and amplitude as the discrete noise signal and an opposite phase.

[0042] Preferably, in a preferred embodiment of the present invention, the signal coupling module 300 is any suitable signal coupling unit, for example, in order to meet the requirements of safety regulations, we can use Y capacitors for coupling. The Y capacitor can couple the corresponding noise compensation signal to the EMC port of the electronic device, thereby offsetting the discrete noise signal corresponding thereto.

[0043] The EMC discrete noise compensation circuit and method of the present invention innovatively introduces a specific noise source, and couples the anti-phase frequency noise signal with the original noise signal, so as to achieve the effect of overall compensation to offset the excessive noise signal, and abandons various complex combination attempts of traditional measures such as filtering, suppression, bypassing, shielding, grounding, etc. The method is simple and clear and easy to implement. It should be noted that the present invention is very effective for isolated and discrete signal compensation, but it is not effective for continuous large-scale signal compensation. In addition, for signals above 20MHz, it is not only limited by the propagation of the line, but the spatial radiation is also not negligible. At the same time, it is limited by the performance of the comparator, and the advantages and effects of this circuit are no longer prominent.

[0044] Figure 2 1 is a circuit diagram of a preferred embodiment of the EMC discrete noise compensation circuit of the present invention. Figure 2 As shown, the EMC discrete noise compensation circuit includes: a noise generating module 100, a gain amplifying module 200 and a signal coupling module 300. The noise generating module 100 is used to generate a square wave signal and a gain adjusting signal based on a discrete noise signal, respectively. The frequency of the square wave signal is the same as the frequency of the discrete noise signal and the phase is opposite. The gain amplifying module 200 is used to generate a noise compensation signal that cancels out the discrete noise signal based on the square wave signal and the gain adjusting signal. The signal coupling module 300 is used to couple the noise compensation signal to an EMC port 400 of an electronic device to cancel out the discrete noise signal.

[0045] Further Figure 2 As shown, in a preferred embodiment of the present invention, the noise generation module 100 includes an MCU unit 120 composed of a high-speed DSP and its peripheral circuits. The MCU unit 120 is used to generate n square wave signals and n gain adjustment signals corresponding to each other based on n discrete noise signals. Figure 2 In the embodiment shown, four-way noise compensation (n=4) is taken as an example. Of course, in other preferred embodiments of the present invention, the design can also be made according to the number of discrete noise signals to be supplemented as needed. Here, the value range of n is a positive integer.

[0046] In a preferred embodiment of the present invention, according to Figure 3The example of measured EMC data of an electronic device without EMC compensation shown in the figure selects discrete noise signals of four isolated and discrete frequency points near 2MHz. As the four discrete noise signals that need to be compensated. The MCU unit 120 generates four square wave signals F1, F2, F3, F4 and four gain adjustment signals VCC_Adj1, VCC_Adj2, VCC_Adj3, VCC_Adj4 corresponding to each other based on the four discrete noise signals. Here, the frequency of the square wave signals F1, F2, F3, F4 is the same as the frequency of the discrete noise signal and the phase is opposite. The gain adjustment signals VCC_Adj1, VCC_Adj2, VCC_Adj3, VCC_Adj4 can be determined according to the amplitudes F1, F2, F3, F4 of the square wave signals and the amplitudes of the discrete noise signals. Here, the role of the MCU unit 120 is to generate the required specific noise source (i.e., square wave signals F1, F2, F3, F4) according to the discrete noise signal to be compensated, and to generate the output duty cycle of the gain adjustment according to the gain requirement (i.e., gain adjustment signals VCC_Adj1, VCC_Adj2, VCC_Adj3, VCC_Adj4). Since the discrete noise signal is directly input into the MCU unit 120 to generate the square wave signal and the gain adjustment signal, the flexibility of MCU programming can be utilized to conveniently set and change the frequency point.

[0047] Of course, in a further preferred embodiment of the present invention, any suitable signal acquisition device can be used to select isolated and discrete discrete noise signals of n frequency points for compensation verification. Here, any known signal acquisition device can be used to implement this function, which all fall within the protection scope of the present invention.

[0048] Further Figure 2 As shown, corresponding to the four groups of square wave signals F1, F2, F3, F4 and the gain adjustment signals VCC_Adj1, VCC_Adj2, VCC_Adj3, VCC_Adj4, the comparator unit 210 includes four comparators U1, U2, U3, U4, and the adjustable power supply unit 220 includes four adjustable voltage branches. The first input end of each adjustable voltage branch is connected to the power supply voltage VCC_15V, the second end receives a gain adjustment signal, and the output end outputs a corresponding voltage adjustment signal. The positive input end and the negative input end of each comparator receive a square wave signal, the positive pole of the power supply receives a corresponding voltage adjustment signal, the negative pole of the power supply is grounded, and the output end outputs a corresponding noise compensation signal. Here, the comparators U1~U4 are preferably high-speed comparators, and the adjustable voltage branch is preferably a BUCK power supply circuit.

[0049] Specifically, each of the adjustable voltage branches includes a switch tube, a diode and a capacitor. Figure 2 As shown, the collector of the switch tube of the first adjustable voltage branch is connected to the first input end of the first adjustable voltage branch to connect to the power supply voltage VCC_15V, the gate is connected to the second end of the first adjustable voltage branch to receive the gain adjustment signal VCC_Adj1, and the emitter is the output end of the first adjustable voltage branch for outputting the voltage adjustment signal VCC_U1; the cathode of the diode and the first end of the capacitor are connected to the emitter of the switch tube, and the anode of the diode and the second end of the capacitor are grounded. The collector of the switch tube of the second adjustable voltage branch is connected to the first input end of the second adjustable voltage branch to connect to the power supply voltage VCC_15V, the gate is connected to the second end of the second adjustable voltage branch to receive the gain adjustment signal VCC_Adj2, and the emitter is the output end of the second adjustable voltage branch for outputting the voltage adjustment signal VCC_U2; the cathode of the diode and the first end of the capacitor are connected to the emitter of the switch tube, and the anode of the diode and the second end of the capacitor are grounded. The collector of the switch tube of the third adjustable voltage branch is connected to the first input end of the third adjustable voltage branch to connect to the power supply voltage VCC_15V, the gate is connected to the second end of the third adjustable voltage branch to receive the gain adjustment signal VCC_Adj3, and the emitter is the output end of the third adjustable voltage branch to output the voltage adjustment signal VCC_U3; the cathode of the diode and the first end of the capacitor are connected to the emitter of the switch tube, and the anode of the diode and the second end of the capacitor are grounded. The collector of the switch tube of the fourth adjustable voltage branch is connected to the first input end of the fourth adjustable voltage branch to connect to the power supply voltage VCC_15V, the gate is connected to the second end of the fourth adjustable voltage branch to receive the gain adjustment signal VCC_Adj4, and the emitter is the output end of the fourth adjustable voltage branch to output the voltage adjustment signal VCC_U4; the cathode of the diode and the first end of the capacitor are connected to the emitter of the switch tube, and the anode of the diode and the second end of the capacitor are grounded.

[0050] The positive phase input terminal and the negative phase input terminal of the comparator U1 both receive the square wave signal F1, the positive pole of the power supply receives the voltage adjustment signal VCC_U1, the negative pole of the power supply is grounded, and the output terminal outputs the corresponding noise compensation signal B1. The positive phase input terminal and the negative phase input terminal of the comparator U2 both receive the square wave signal F2, the positive pole of the power supply receives the voltage adjustment signal VCC_U2, the negative pole of the power supply is grounded, and the output terminal outputs the corresponding noise compensation signal B2. The positive phase input terminal and the negative phase input terminal of the comparator U3 both receive the square wave signal F3, the positive pole of the power supply receives the voltage adjustment signal VCC_U3, the negative pole of the power supply is grounded, and the output terminal outputs the corresponding noise compensation signal B3. The positive phase input terminal and the negative phase input terminal of the comparator U4 both receive the square wave signal F4, the positive pole of the power supply receives the voltage adjustment signal VCC_U4, the negative pole of the power supply is grounded, and the output terminal outputs the corresponding noise compensation signal B4.

[0051] By adopting n-way comparators and an adjustable power supply unit, the square wave signals F1 to F4 output by the MCU unit can be amplified with controllable gain, and the actual amplified gain multiple is determined by the output duty cycle (i.e., gain adjustment signals VCC_Adj1, VCC_Adj2, VCC_Adj3, VCC_Adj4) of the MCU unit to adjust the gain as needed. Since the gain adjustment signals VCC_Adj1, VCC_Adj2, VCC_Adj3, and VCC_Adj4 are generated based on the discrete noise signal to be compensated, it can be ensured that the noise compensation signals B1 to B4 generated at the end have the same frequency and amplitude as the discrete noise signal and are opposite in phase, so coupling compensation can be achieved.

[0052] Further Figure 2 As shown, the signal coupling module 300 includes n coupling units, a first end of each coupling unit is connected to an output end of a comparator to receive a corresponding noise compensation signal, and a second end is connected to an L line or an N line of an EMC port of the electronic device. Preferably, each coupling unit includes a Y capacitor.

[0053] Specifically, one end of the Y capacitor C1 receives the noise compensation signal B1, and the other end is connected to the N line of the EMC port of the electronic device. One end of the Y capacitor C2 receives the noise compensation signal B2, and the other end is connected to the N line of the EMC port of the electronic device. One end of the Y capacitor C3 receives the noise compensation signal B3, and the other end is connected to the L line of the EMC port of the electronic device. One end of the Y capacitor C4 receives the noise compensation signal B4, and the other end is connected to the L line of the EMC port of the electronic device.

[0054] Here, the Y capacitor can couple the noise compensation signals B1-B4 to the input or output line of the EMC port of the electronic device, that is, the L line or the N line. At this time, because the frequency range of the EMC test is basically above 150KHz, or even above MHz, the noise compensation signals B1-B4 can be coupled through the Y capacitor and injected into the actual line.

[0055] Of course, the choice of L line or N line can be determined according to the actual circuit. From the perspective of time domain, the difference between the peak of the output square wave at time 0 on the L line and the trough on the N line is significant. However, in terms of compensation effect, the same effect can be achieved.

[0056] Figure 3 This is an example of measured EMC data of electronic equipment when EMC compensation is not performed. Figure 4 This is an example of measured EMC data of an electronic device after EMC compensation using the EMC discrete noise compensation circuit of the present invention. Figures 3-4 The principle of the present invention is explained as follows.

[0057] First, test the frequency point and value of the excess to be compensated, that is, obtain the discrete noise signal that needs to be compensated. In order to obtain better results, it is preferred that the frequency of the discrete noise signal is less than 20MHz. Figure 3 For example, a discrete noise signal with four isolated and discrete frequency points near 2MHz is selected for compensation verification. Subsequently, the MCU unit uses the IO port to create four square wave signals F1 to F4 of the same frequency, where the frequencies of the square wave signals F1, F2, F3, and F4 are the same as the frequencies of the discrete noise signals and have opposite phases. The gain adjustment signals VCC_Adj1, VCC_Adj2, VCC_Adj3, and VCC_Adj4 are determined according to the amplitudes F1, F2, F3, and F4 of the square wave signals and the amplitudes of the discrete noise signals.

[0058] The square wave signals F1-F4 are input into each comparator, and the gain adjustment signals VCC_Adj1, VCC_Adj2, VCC_Adj3, VCC_Adj4 are input into each adjustable voltage branch to obtain the voltage adjustment signals VCC_U1, VCC_U2, VCC_U3, VCC_U4 of each comparator. Because the voltage adjustment signals of the power supply output of each comparator are different, the peak values ​​of the waveforms output by each comparator are also different, that is, the compensation signal amplitudes of each channel (frequency point) can be different. Therefore, corresponding noise compensation signals can be generated for different discrete noise signals.

[0059] Due to safety regulations, the coupling channel can only be injected through Y capacitors. Specifically, the noise compensation signal can be sent to the L line or the N line. From the perspective of time domain, the difference between the peak of the output square wave at the time 0 on the L line and the trough on the N line is different, but in terms of compensation effect, the same effect can be achieved. Figure 4 In the figure, we can see the actual effect after compensation by this circuit. Although the discrete signals near 2MHz are still there, the measured conduction amplitudes are greatly reduced compared with those before rectification.

[0060] The EMC discrete noise compensation circuit of the present invention, for some isolated and discrete discrete noise signals of over-standard frequency points, abandons the method of eliminating the noise source, and abandons various complex combination attempts of traditional measures such as filtering, suppression, bypassing, shielding, grounding, etc., and specially introduces or creates a specific new noise source; this noise source combines the characteristics of over-standard noise and can be applied to any frequency point, and through the reverse output, it is coupled with the original noise to achieve the effect of overall offsetting the over-standard noise. It is especially suitable for the occurrence of multiple discrete and changing over-standard frequency points. And the discrete noise signals of multiple isolated over-standard frequency points can be compensated simultaneously, and the specific number limit is limited to the number of IO ports of the MCU unit; by adjusting the VCC voltage of the comparator, the amplitude (and gain) of the new signal can also be arbitrarily adjusted, and the amplitude output can be customized quantitatively.

[0061] exist Figure 2 In the preferred embodiment shown, the EMC discrete noise compensation circuit of the present invention may further include a fine-tuning module 500, which reacquires the discrete noise signal after the cancellation is completed, and compares the reacquired discrete noise signal with the expected value. If the expected value is not reached, the frequency or inverted amplitude of the output signal may be fine-tuned, that is, the square wave signal and / or the gain adjustment signal corresponding to the discrete noise signal may be fine-tuned based on the comparison result, thereby fine-tuning the frequency and / or amplitude of the corresponding noise compensation signal.

[0062] In this preferred embodiment, the fine-tuning module 500 can be integrated in the MCU, so that the frequency can be easily set and changed by utilizing the flexibility of MCU programming. In a further preferred embodiment of the present invention, a measurement circuit can be introduced to realize dynamic self-active feedback adjustment.

[0063] Figure 5 : is a flow chart of the EMC discrete noise compensation method of the present invention. Figure 5 As shown, the EMC discrete noise compensation method of the present invention can be applied to any of the aforementioned EMC discrete noise compensation circuits, and comprises the following steps:

[0064] S1, generating a set of square wave signals and gain adjustment signals based on each discrete noise signal in a one-to-one correspondence, wherein the frequency of each square wave signal is the same as the frequency of the corresponding discrete noise signal and the phase is opposite;

[0065] S2, generating a noise compensation signal based on each set of square wave signals and gain adjustment signals to cancel out the corresponding discrete noise signal, wherein each noise compensation signal has the same frequency and amplitude as its corresponding discrete noise signal and has an opposite phase;

[0066] S3. Coupling the noise compensation signal to an EMC port of an electronic device to offset the corresponding discrete noise signal.

[0067] Through actual measurement, the effect after compensation is obtained. If the expected value is not reached, the frequency or inverted amplitude of the output signal can be fine-tuned. That is, the discrete noise signal is re-acquired after the cancellation is completed, and the re-acquired discrete noise signal is compared with the expected value, and the square wave signal and / or the gain adjustment signal corresponding to the discrete noise signal are fine-tuned based on the comparison result, thereby fine-tuning the frequency and / or amplitude of the corresponding noise compensation signal.

[0068] Here, the specific embodiments of the EMC discrete noise compensation method of the present invention can refer to Figures 1 to 4 The description of the EMC discrete noise compensation circuit shown will not be repeated here.

[0069] Although the present invention is described by specific embodiments, it should be understood by those skilled in the art that various changes and equivalent substitutions may be made to the present invention without departing from the scope of the present invention. In addition, various modifications may be made to the present invention for specific situations or materials without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed, but should include all implementation methods falling within the scope of the claims of the present invention.

[0070] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An EMC discrete noise compensation circuit, characterized in that: include: A noise generating module, used to generate a square wave signal and a gain adjustment signal based on a discrete noise signal, wherein the frequency of the square wave signal is the same as that of the discrete noise signal and the phase is opposite; A gain amplification module, configured to generate a noise compensation signal that cancels out the discrete noise signal based on the square wave signal and the gain adjustment signal; as well as A signal coupling module, used for coupling the noise compensation signal to an EMC port of an electronic device to offset the discrete noise signal; The gain amplification module includes a comparator unit and an adjustable power supply unit; The adjustable power supply unit is used to receive the gain adjustment signal and generate a voltage adjustment signal based on the gain adjustment signal; The comparator unit is used to receive the square wave signal and the voltage adjustment signal, and adjust the amplitude of the square wave signal based on the voltage adjustment signal to obtain the noise compensation signal; the noise compensation signal has the same frequency and amplitude as the discrete noise signal and an opposite phase.

2. The EMC discrete noise compensation circuit according to claim 1, characterized in that: The noise generation module comprises: The MCU unit is used to generate n square wave signals and n gain adjustment signals corresponding to each other based on n discrete noise signals; wherein n is a positive integer.

3. The EMC discrete noise compensation circuit according to claim 2, characterized in that: The comparator unit includes n comparators, and the adjustable power supply unit includes n adjustable voltage branches; The first input end of each adjustable voltage branch is connected to the power supply voltage, the second end receives a gain adjustment signal, and the output end outputs a corresponding voltage adjustment signal; The positive input terminal and the negative input terminal of each comparator receive a square wave signal, the positive pole of the power supply receives a corresponding voltage regulation signal, the negative pole of the power supply is grounded, and the output terminal outputs a corresponding noise compensation signal.

4. The EMC discrete noise compensation circuit according to claim 3, characterized in that: The adjustable voltage branch includes a switch tube, a diode and a capacitor; The collector of the switch tube is connected to the first input end of the adjustable voltage branch, the gate is connected to the second end of the adjustable voltage branch, and the emitter is the output end of the adjustable voltage branch; the cathode of the diode and the first end of the capacitor are connected to the emitter of the switch tube, and the anode of the diode and the second end of the capacitor are grounded.

5. The EMC discrete noise compensation circuit according to claim 3, characterized in that: The signal coupling module comprises n coupling units, a first end of each coupling unit is connected to an output end of a comparator to receive a corresponding noise compensation signal, and a second end is connected to an L line or an N line of an EMC port of the electronic device.

6. The EMC discrete noise compensation circuit according to claim 5, characterized in that: The coupling unit includes a Y capacitor.

7. The EMC discrete noise compensation circuit according to any one of claims 2 to 6, characterized in that: It further includes a fine-tuning module, which is used to reacquire the discrete noise signal after the cancellation is completed, compare the reacquired discrete noise signal with the expected value, and fine-tune the square wave signal and / or the gain adjustment signal corresponding to the discrete noise signal based on the comparison result, thereby fine-tuning the frequency and / or amplitude of the corresponding noise compensation signal.

8. An EMC discrete noise compensation method, applied to the EMC discrete noise compensation circuit according to any one of claims 1 to 7; characterized in that: The following steps are involved: S1, generating a set of square wave signals and gain adjustment signals based on each discrete noise signal in a one-to-one correspondence, wherein the frequency of each square wave signal is the same as the frequency of the corresponding discrete noise signal and the phase is opposite; S2, generating a noise compensation signal based on each set of square wave signals and gain adjustment signals to cancel out the corresponding discrete noise signal, wherein each noise compensation signal has the same frequency and amplitude as its corresponding discrete noise signal and has an opposite phase; S3. Coupling the noise compensation signal to an EMC port of an electronic device to offset the corresponding discrete noise signal.

9. The EMC discrete noise compensation method according to claim 8, characterized in that: Further comprising the steps of: S4. After the cancellation is completed, the discrete noise signal is reacquired, and the reacquired discrete noise signal is compared with the expected value, and the square wave signal and / or the gain adjustment signal corresponding to the discrete noise signal are fine-tuned based on the comparison result, thereby fine-tuning the frequency and / or amplitude of the corresponding noise compensation signal.

10. The EMC discrete noise compensation method according to claim 9, characterized in that: The frequency of the discrete noise signal is less than 20 MHz.

Images