Universal anti-resonance electromagnetic compatibility suppression circuit

Abstract

The invention belongs to the technical field of electromagnetic compatibility suppression design, and particularly relates to a universal anti-resonance electromagnetic compatibility suppression circuit which avoids noise amplification under the same frequency by adopting a resonant frequency conversion method instead of a damping resistance increasing method compared with an existing electromagnetic compatibility suppression measure. The damping resistance is increased, the improvement effect is achieved after resonance is generated, ripple increase caused by resonance is avoided, in addition, ripple amplitude control can be carried out in real time according to needs, it is ensured that ripples are within an acceptable range, and the ripple control circuit has universality and is low in cost and small in size.

Description

Technical Field

[0001] The present application belongs to the technical field of electromagnetic compatibility suppression design, and specifically relates to a universal anti-resonance electromagnetic compatibility suppression circuit. Background Art

[0002] Electronic equipment is developing towards intelligence, integration and miniaturization. The functions and designs of products are becoming more and more complex. The required processor functions are becoming more and more complex, the circuit integration is getting higher and higher, the power consumption is increasing, and the required power supply faces many types, low voltage, high current and other problems. Combined with the power supply requirements, using a switching power supply to generate the multiple tertiary power supplies required by the processor is the most reasonable choice. In most cases, the main controller needs to provide multiple different power supplies, each of which is generated by a switching power supply chip. In order to produce high efficiency, the switching frequency is generally high, which is easy to generate electromagnetic interference. In this regard, at present, special filters, RC filters or magnetic beads + capacitor filters are mostly used in power supply circuits for electromagnetic compatibility suppression.

[0003] A dedicated filter is used in the power supply circuit to suppress electromagnetic compatibility. A single dedicated filter is expensive, and there are many types of main controller power supplies. If a dedicated filter is added to each circuit, the total price will be high, and the filter is generally large in size, making it difficult to use in equipment with a small space.

[0004] RC filters are used in power supply circuits for electromagnetic compatibility suppression. Resistors can suppress all harmonics from low frequency to high frequency by absorbing noise. However, there will be a voltage drop across the resistor under DC conditions. Generally, the power supply current is relatively large, resulting in a small steady-state value of the power supply, which can cause functional failures. In addition, the same switching power supply chip cannot be used universally when connected to different loads. Since the load characteristics cannot be predicted in many cases, the parameters can only be determined through continuous manual attempts.

[0005] Using a magnetic bead + capacitor filter in a power supply circuit for electromagnetic compatibility suppression is usually effective because magnetic beads are mainly used to filter out high frequencies. However, magnetic beads tend to resonate with the capacitors at the back end at a certain frequency. When the resonant frequency is close to the switching frequency of the switching power supply chip, the power supply ripple will increase. Although the switching frequency of the switching power supply chip is known, the load of each power supply is different, and the parameters of the parasitic inductance of the magnetic beads cannot be predicted. The same magnetic bead + capacitor will have different conditions in different circuits.

[0006] This application is proposed in view of the above-mentioned technical defects. Summary of the invention

[0007] The purpose of the present application is to provide a universal anti-resonance electromagnetic compatibility suppression circuit, which is used to solve the electromagnetic compatibility suppression problem of multi-channel switching power supplies when carrying different loads in a universal and low-cost manner.

[0008] The technical solution of this application is:

[0009] A universal anti-resonance electromagnetic compatibility suppression circuit, comprising:

[0010] The filter module has an input end connected to the output end of the switching power supply chip, an output end connected to the power load, and has multiple different frequency filter channels;

[0011] The input end of the signal detection module is connected to the output end of the filter module, and the AC signal in the output power signal of the filter module is identified to obtain a ripple AC signal;

[0012] The ripple detection module, whose input end is connected to the output end of the signal detection module, transforms the ripple AC signal into a smooth signal, and then collects the amplitude of the smooth signal to obtain the ripple value of the ripple AC signal;

[0013] The frequency detection module has an input end connected to the output end of the signal detection module to detect and obtain the frequency value of the ripple AC signal;

[0014] Real-time loading configuration module to configure the amplitude and frequency limit value of the ripple AC signal;

[0015] The control module is connected to the switching power supply chip for power supply, the input end is connected to the input end of the ripple detection module, the frequency detection module, and the real-time loading configuration module, and the output end is connected to the control end of the filter module. When the ripple value or frequency value of the ripple AC signal exceeds the amplitude and frequency limit value of the ripple AC signal, the frequency filtering channel of the filter module is switched until the ripple value and frequency value of the ripple AC signal are less than the amplitude and frequency limit value of the ripple AC signal.

[0016] Optionally, in the above-mentioned universal anti-resonance electromagnetic compatibility suppression circuit, the filtering module uses an operational amplifier OPA1604 to form a second-order active filter, and magnetic beads and capacitors with different parameters are set in the four channels of the operational amplifier OPA1604.

[0017] Optionally, in the above-mentioned universal anti-resonance electromagnetic compatibility suppression circuit, the signal detection module is implemented by a differential amplifier and is designed using a differential to single-ended chip. The differential to single-ended chip is AD8221TRMZ-EP from ADI. The differential input + is connected to the output of the filter module, and the differential input - is connected to the reference power supply.

[0018] Optionally, in the above-mentioned universal anti-resonance electromagnetic compatibility suppression circuit, the ripple detection module is designed to be composed of a rectifier circuit + an ADC acquisition circuit, wherein the rectifier circuit converts the AC signal into a smooth signal, and the ADC acquisition circuit acquires the ripple value at a certain sampling rate;

[0019] The rectifier circuit in the ripple detection module is built by the op amp OPA1604, including op amp OPA1604U1 and op amp OPA1604U2. The negative input terminal of the op amp OPA1604U1 is connected to the power supply Vin through the resistor R1, the positive input terminal is grounded through the resistor R6, and the output terminal is connected to the negative input terminal of the op amp OPA1604U2 through the diode D1 and the resistor R3. The negative direction of the diode D1 is toward the output terminal of the op amp OPA1604U1; the positive input terminal of the op amp OPA1604U2 is grounded through the resistor R7; the output terminal of the op amp OPA1604U1 The circuit between the diode D1 and the resistor R3 is connected to the negative input terminal of the op amp OPA1604U2 through the resistor R2; the output terminal of the op amp OPA1604U2 is connected to the circuit between the power supply Vin and the resistor R1 through the resistor R4 and the resistor R5; the circuit between the resistor R4 and the resistor R5 is connected to the circuit between the diode D1 and the resistor R3; the resistor R4 is equal to the resistor R5;

[0020] The ADC acquisition circuit in the ripple detection module uses AD7606 from ADI.

[0021] Optionally, in the above-mentioned universal anti-resonance electromagnetic compatibility suppression circuit, the frequency detection module is implemented by a comparator, and a reference value is set. When the amplitude of the ripple AC signal exceeds the reference value, the output is high, and when the amplitude of the ripple AC signal is lower than the reference value, the output is low;

[0022] The comparator in the frequency detection module specifically adopts LMV393ID, the ripple AC signal is connected to the inverting terminal of LMV393ID, and the internal power supply is connected to the non-inverting terminal of LMV393ID through a resistor divider as a reference value.

[0023] Optionally, in the above-mentioned universal anti-resonance electromagnetic compatibility suppression circuit, the control module design consists of a general processor + an affiliated minimum system, the input port of the general processor is connected to the crystal oscillator and reset, the output port is connected to the input of the NOT gate and the level matching, the output of the NOT gate is connected to the level matching control end, the level matching output is connected to the input of the optocoupler, the output of the optocoupler is connected to the gate of the PMOS tube, the source of the PMOS tube is connected to the switching power supply chip, and the drain is connected to the general processor.

[0024] A universal anti-resonance electromagnetic compatibility suppression circuit is provided. Compared with the existing electromagnetic compatibility suppression measures, the method of converting the resonant frequency is adopted to avoid noise amplification at the same frequency, rather than increasing the damping resistance. Increasing the damping resistance is an improvement effect after the resonance is generated, which avoids the increase of ripples caused by the resonance. In addition, the ripple amplitude can be controlled in real time as needed to ensure that the ripple is within an acceptable range. The circuit has universality, low cost and small size. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic diagram of a universal anti-resonance electromagnetic compatibility suppression circuit provided in an embodiment of the present application;

[0026] Figure 2 is a schematic diagram of a rectifier circuit in a ripple detection module provided in an embodiment of the present application;

[0027] Figure 3 It is a schematic diagram of a control module provided in an embodiment of the present application.

[0028] In order to better illustrate the present embodiment, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product. In addition, the drawings are only used for illustrative purposes and should not be construed as limitations on the present application. DETAILED DESCRIPTION

[0029] In order to make the technical solution and advantages of the present application clearer, the technical solution of the present application will be described in further detail in detail and in detail with reference to the accompanying drawings. It can be understood that the specific embodiments described here are only partial embodiments of the present application, which are only used to explain the present application, not to limit the present application. It should be noted that, for the convenience of description, only the parts related to the present application are shown in the accompanying drawings, and other related parts can refer to the general design.

[0030] In addition, unless otherwise defined, the technical terms or scientific terms used in the description of this application should be the common meanings understood by those skilled in the art in the field to which this application belongs. The term "include" used in the description of this application means that the elements or objects appearing before the term include the elements or objects listed after the term and their equivalents, but do not exclude other elements or objects.

[0031] In addition, it should be noted that, unless otherwise clearly specified and limited, the words "installation", "connection" and similar terms used in the description of this application should be understood in a broad sense. For example, the connection can be a fixed connection or a detachable connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. Technical personnel in the field can understand its specific meaning in this application according to the specific circumstances.

[0032] A universal anti-resonance electromagnetic compatibility suppression circuit, such as Figure 1 As shown, it includes a filtering module, a signal detection module, a ripple detection module, a frequency detection module, a real-time loading configuration module, and a control module.

[0033] The input end of the filter module is connected to the output end of the switching power supply chip, and the output end is connected to the power load, and has multiple different frequency filter channels.

[0034] Each frequency filter channel of the filter module is set with magnetic beads and capacitors with different parameters to make the resonant frequency different. Since the frequency of the transition band of magnetic beads and capacitor passive filters is relatively wide, it may affect the electromagnetic compatibility effect. An active second-order filter can be used to improve it. Specifically, the second-order active filter can be formed by using the operational amplifier OPA1604. The operational amplifier OPA1604 has 4 channels, and different magnetic beads and capacitor parameters are set in each channel.

[0035] The input end of the signal detection module is connected to the output end of the filter module, and the AC signal in the output power signal of the filter module is identified to obtain a ripple AC signal.

[0036] The signal detection module is implemented by a differential amplifier and can be designed with a differential to single-ended chip. The differential to single-ended chip can be AD8221TRMZ-EP from ADI. The differential input + is connected to the output of the filter module, and the differential input - is connected to the reference power supply, so that the AC signal in the output power signal of the filter module can be detected. Compared with the traditional signal detection module that uses capacitors to form a high-pass filter, a poor cutoff frequency design will greatly affect the extraction of the AC signal.

[0037] The input end of the ripple detection module is connected to the output end of the signal detection module, the ripple AC signal is rectified into a smooth signal, and then the amplitude of the smooth signal is collected to obtain the ripple value of the ripple AC signal.

[0038] The ripple detection module can be designed to consist of a rectifier circuit + an ADC acquisition circuit, wherein the rectifier circuit converts the AC signal into a smooth signal, and the ADC acquisition circuit acquires the ripple value at a certain sampling rate.

[0039] The rectifier circuit in the ripple detection module can be built by the operational amplifier OPA1604, which is a precision rectifier circuit. Figure 2As shown, it includes an op amp OPA1604U1 and an op amp OPA1604U2, wherein the negative phase input terminal of the op amp OPA1604U1 is connected to the power supply Vin through a resistor R1, the positive phase input terminal is grounded through a resistor R6, the output terminal is connected to the negative phase input terminal of the op amp OPA1604U2 through a diode D1 and a resistor R3, and the negative direction of the diode D1 is toward the output terminal of the op amp OPA1604U1; the positive phase input terminal of the op amp OPA1604U2 is grounded through a resistor R7; the circuit between the output terminal of the op amp OPA1604U1 and the diode D1 , connected to the negative input terminal of op amp OPA1604U2 through diode D2, with the cathode of diode D2 facing the negative input terminal of op amp OPA1604U1; the circuit between diode D1 and resistor R3 is connected to the negative input terminal of op amp OPA1604U2 through resistor R2; the output terminal of op amp OPA1604U2 is connected to the circuit between power supply Vin and resistor R1 through resistor R4 and resistor R5; the circuit between resistor R4 and resistor R5 is connected to the circuit between diode D1 and resistor R3; resistor R4 is equal to resistor R5.

[0040] When the input voltage of the power supply Vin is in the negative half, the diode D2 is forward biased, which will make the output of the op amp OPA1604U1 0.6V higher than the power supply Vin. At this time, the power supply Vin, resistor R4, resistor R5, op amp OPA1604U2, and resistor R7 will form an inverting amplifier. Since resistors R4 and R5 are the same, the output VOUT of the op amp OPA1604U2 is -Vin, which is the positive half. When the input voltage of the power supply Vin is in the positive half, the output of the op amp OPA1604U1 is negative, and the diode D1 is forward biased. At this time, the output of the op amp OPA1604U1 is -2Vin. After passing through the inverting amplifier formed by the op amp OPA1604U2, the output Vout of the op amp OPA1604U2 is 2Vin. At the same time, the positive AC input voltage Vin will also reach the inverting input terminal of the op amp OPA1604U2 through the resistor R4, making the output Vout of the op amp OPA1604U2 =-Vin. Therefore, the output Vout of the op amp OPA1604U2 is =2Vin-Vin=Vin, which is the positive half.

[0041] The rectifier circuit in the ripple detection module adopts precision rectification. Compared with the traditional method of direct measurement with an oscilloscope or detection with a spectrum analyzer, the oscilloscope has poor measurement accuracy and the spectrum analyzer method has poor real-time performance. The precision rectifier circuit has good real-time performance and can quickly respond to and process ripple signals.

[0042] The ADC acquisition circuit in the ripple detection module can use ADI's AD7606. This chip supports up to 8 analog channel inputs, 16-bit sampling, conversion time <4μs, and a single-channel maximum analog input range of ±10V. The minimum resolution LSB = 0.0003V can be obtained, which can far meet the requirements of ripple detection.

[0043] The input end of the frequency detection module is connected to the output end of the signal detection module to detect and obtain the frequency value of the ripple AC signal.

[0044] The frequency detection module can be implemented by a comparator. A comparator reference value is set. When the ripple AC signal amplitude exceeds the reference value, the output is high. When the ripple AC signal amplitude is lower than the reference value, the output is low. The output of the comparator is a square wave. The frequency value can be obtained by calculating the interval between adjacent rising edges in the square wave.

[0045] The comparator in the frequency detection module can specifically use LMV393ID. The ripple AC signal is connected to the inverting end of LMV393ID. The internal power supply is connected to the non-inverting end of LMV393ID through a resistor divider as a reference value. When the amplitude of the ripple AC signal exceeds the reference value, the output is high. When the amplitude of the ripple AC signal is lower than the reference value, the output is low.

[0046] The frequency detection module is implemented using a comparator, which can effectively distinguish between signals above and below the reference value, thereby reducing the impact of noise on frequency detection. Compared with traditional digital frequency counters, the system's adjustability and flexibility can be increased by setting different thresholds, and it can be quickly adjusted and optimized according to different scenario requirements.

[0047] The real-time loading configuration module is used to configure the amplitude and frequency limit values ​​of the ripple AC signal.

[0048] Different power loads have different allowable ripple frequency and amplitude ranges. The real-time loading configuration module can configure the amplitude and frequency limit value of the ripple AC signal on the host computer for adaptation.

[0049] The control module is connected to the switching power supply chip for power supply, the input end is connected to the input end of the ripple detection module, the frequency detection module, and the real-time loading configuration module, and the output end is connected to the control end of the filter module. When the ripple value or frequency value of the ripple AC signal exceeds the amplitude and frequency limit value of the ripple AC signal, the frequency filtering channel of the filter module is switched until the ripple value and frequency value of the ripple AC signal are less than the amplitude and frequency limit value of the ripple AC signal.

[0050] The control module can be designed to consist of a switch power supply chip load, i.e. a general purpose processor + an attached minimum system, such as Figure 3As shown, the input pin of the general processor is connected to the crystal oscillator and reset, the output pin is connected to the input of the NOT gate and the level matching, the output of the NOT gate is connected to the control end of the level matching, the output of the level matching is connected to the input of the optocoupler, the output of the optocoupler is connected to the gate of the PMOS tube, the source of the PMOS tube is connected to the switching power supply chip, and the drain is connected to the general processor. When powered on, the switching power supply chip is directly connected to the general processor through the PMOS tube to supply power to it. At this time, the part directly output by the switching power supply chip is not resonant, so the general processor is powered normally. When the general processor detects that the power supply after the magnetic bead filtering has resonant noise, it switches to different frequency filtering channels until the ripple value meets the requirements. After meeting the requirements, the PMOS tube is turned off (is it the output pin self-locking? Please describe the process of output pin self-locking), so that the switching power supply chip can supply power to the general processor after being processed by the filtering module to meet the electromagnetic compatibility requirements.

[0051] The control module uses the load of the switching power supply chip, that is, the general processor, to achieve hardware sharing, and the software uses partition storage to improve the resource utilization of the general processor, which can avoid adding a control module and reduce costs. The control module uses an output pin self-locking method to safely control the PMOS tube that supplies power to the control module, so that the output pin will not be uncontrolled during the power-on configuration program, and the power supply of the control module is directly connected to the switching power supply chip through the PMOS tube, and there is no resonance. At the same time, it can avoid using another power chip to power the control module.

[0052] The universal anti-resonance electromagnetic compatibility suppression circuit disclosed in the above embodiment can be applied to power supply interference suppression in household appliances to prevent various household appliances from being connected to household power supply lines. If the electromagnetic interference is not suppressed, it will affect the quality of the power supply line and the normal operation of the household appliances. In addition, it can be applied to power management in electric vehicles to ensure the normal operation of electronic equipment and improve the overall electromagnetic compatibility of the vehicle. It can also be applied to power supply filtering of communication base stations to suppress the power supply interference of communication base stations, which can make signal transmission more stable and clear, and improve the performance and reliability of communication base stations.

[0053] So far, the technical solution of the present application has been described in conjunction with the preferred embodiments shown in the accompanying drawings. Those skilled in the art should understand that the scope of protection of the present application is obviously not limited to these specific embodiments. Without departing from the principles of the present application, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the scope of protection of the present application.

Claims

1. A universal anti-resonance electromagnetic compatibility suppression circuit, characterized in that: include: The filter module has an input end connected to the output end of the switching power supply chip, an output end connected to the power load, and has multiple different frequency filter channels; The input end of the signal detection module is connected to the output end of the filter module, and the AC signal in the output power signal of the filter module is identified to obtain a ripple AC signal; The ripple detection module, whose input end is connected to the output end of the signal detection module, transforms the ripple AC signal into a smooth signal, and then collects the amplitude of the smooth signal to obtain the ripple value of the ripple AC signal; The frequency detection module has an input end connected to the output end of the signal detection module to detect and obtain the frequency value of the ripple AC signal; Real-time loading configuration module to configure the amplitude and frequency limit value of the ripple AC signal; The control module is connected to the switching power supply chip for power supply, the input end is connected to the input end of the ripple detection module, the frequency detection module, and the real-time loading configuration module, and the output end is connected to the control end of the filter module. When the ripple value or frequency value of the ripple AC signal exceeds the amplitude and frequency limit value of the ripple AC signal, the frequency filtering channel of the filter module is switched until the ripple value and frequency value of the ripple AC signal are less than the amplitude and frequency limit value of the ripple AC signal.

2. The universal anti-resonance electromagnetic compatibility suppression circuit according to claim 1, characterized in that: The filter module uses the operational amplifier OPA1604 to form a second-order active filter, and magnetic beads and capacitors with different parameters are set in the four channels of the operational amplifier OPA1604.

3. The universal anti-resonance electromagnetic compatibility suppression circuit according to claim 2, characterized in that: The signal detection module is implemented with a differential amplifier and is designed using a differential to single-ended chip. The differential to single-ended chip is AD8221TRMZ-EP from ADI. The differential input + is connected to the output of the filter module, and the differential input - is connected to the reference power supply.

4. The universal anti-resonance electromagnetic compatibility suppression circuit according to claim 3, characterized in that: The ripple detection module design consists of a rectifier circuit + ADC acquisition circuit, where the rectifier circuit transforms the AC signal into a smooth signal, and the ADC acquisition circuit acquires the ripple value at a certain sampling rate; The rectifier circuit in the ripple detection module is built by the op amp OPA1604, including op amp OPA1604U1 and op amp OPA1604U2. The negative input terminal of the op amp OPA1604U1 is connected to the power supply Vin through the resistor R1, the positive input terminal is grounded through the resistor R6, and the output terminal is connected to the negative input terminal of the op amp OPA1604U2 through the diode D1 and the resistor R3. The negative direction of the diode D1 is toward the output terminal of the op amp OPA1604U1; the positive input terminal of the op amp OPA1604U2 is grounded through the resistor R7; the output terminal of the op amp OPA1604U1 The circuit between the diode D1 and the resistor R3 is connected to the negative input terminal of the op amp OPA1604U2 through the resistor R2; the output terminal of the op amp OPA1604U2 is connected to the circuit between the power supply Vin and the resistor R1 through the resistor R4 and the resistor R5; the circuit between the resistor R4 and the resistor R5 is connected to the circuit between the diode D1 and the resistor R3; the resistor R4 is equal to the resistor R5; The ADC acquisition circuit in the ripple detection module uses AD7606 from ADI.

5. The universal anti-resonance electromagnetic compatibility suppression circuit according to claim 4, characterized in that: The frequency detection module is implemented by a comparator, which sets a reference value. When the ripple AC signal amplitude exceeds the reference value, the output is high, and when the ripple AC signal amplitude is lower than the reference value, the output is low. The comparator in the frequency detection module specifically adopts LMV393ID, the ripple AC signal is connected to the inverting terminal of LMV393ID, and the internal power supply is connected to the non-inverting terminal of LMV393ID through a resistor divider as a reference value.

6. The universal anti-resonance electromagnetic compatibility suppression circuit according to claim 5, characterized in that: The control module design consists of a general-purpose processor + an attached minimum system. The input port of the general-purpose processor is connected to the crystal oscillator and reset, and the output port is connected to the input of the NOT gate and the level matching. The output of the NOT gate is connected to the level matching control end, and the level matching output is connected to the input of the optocoupler. The output of the optocoupler is connected to the gate of the PMOS tube, the source of the PMOS tube is connected to the switching power supply chip, and the drain is connected to the general-purpose processor.

Images