An electromagnetic interference suppression circuit, method and electrical appliance

Abstract

This invention discloses an electromagnetic interference (EMI) suppression circuit, method, and electrical device. The EMI suppression circuit includes: an interference cancellation module, grounded, for outputting a cancellation signal to cancel EMI signals generated when the switching transistor drive circuit of the electrical device outputs a switch control signal; and a processing chip, connected to the interference cancellation module, for controlling the timing of the cancellation signal output based on the timing of the switch control signal output by the switching transistor drive circuit, and controlling the direction of the cancellation signal based on the direction of the EMI signal. This invention enables active EMI suppression based on the direction and timing of the EMI signal, achieving good EMI suppression effects for EMI signals of different frequencies.

Description

Technical Field

[0001] This invention relates to the field of electronic power technology, and more specifically, to an electromagnetic interference suppression circuit, method, and electrical equipment. Background Technology

[0002] Electromagnetic interference includes three aspects: harmonics, conducted interference, and radiated interference. Harmonic suppression usually employs two solutions: passive and active power correction (PFC) circuits. Conducted interference and radiated interference are currently suppressed by passive filtering. However, since conducted interference and radiated interference are usually at higher frequencies and are greatly affected by the power grid, electrical equipment, interference sources, parasitic parameters, and working environment, they are more difficult to suppress.

[0003] Passive filtering is a type of passive filtering method. When using passive filter circuits as electromagnetic interference suppression circuits to suppress conducted and radiated interference, the components typically used in passive filter circuits are chokes and capacitors. These not only have disadvantages such as large material size and high price, but also, since the filtering parameters of the components are set, the frequency characteristics of the filter are already determined. They can only filter out interference signals of specific frequencies, and their frequency range is limited. When the interference signals generated by the electrical equipment exceed their frequency range, the interference suppression effect is poor.

[0004] There is currently no effective solution to the problem that the frequency range applicable to existing passive electromagnetic interference suppression schemes is limited. Summary of the Invention

[0005] This invention provides an electromagnetic interference suppression circuit, method, and electrical device to solve the problem that existing passive electromagnetic interference suppression schemes cannot achieve good interference suppression effects for electromagnetic interference signals outside their frequency range.

[0006] To solve the above-mentioned technical problems, the present invention provides an electromagnetic interference suppression circuit, applied to electrical equipment with a switching transistor drive circuit, characterized in that the circuit includes:

[0007] An interference cancellation module, grounded, is used to output a cancellation signal to cancel the electromagnetic interference signal generated when the switching control signal is output by the switching transistor drive circuit of the electrical equipment.

[0008] The processing chip, connected to the interference cancellation module, is used to control the output timing of the cancellation signal according to the timing of the switch control signal output by the switch drive circuit, and to control the direction of the cancellation signal according to the direction of the electromagnetic interference signal.

[0009] Furthermore, the circuit also includes:

[0010] The sampling module has its first end connected to the reference ground of the switching transistor drive circuit, its second end grounded, and its third end connected to the processing chip. It is used to detect the direction of the electromagnetic interference signal generated when the switching transistor drive circuit outputs the switching control signal.

[0011] Furthermore, the sampling module is also used to: detect the magnitude of the electromagnetic interference signal generated when the switching control signal is output by the switching transistor drive circuit;

[0012] The processing chip is further configured to: control the magnitude of the cancellation signal based on the magnitude of the electromagnetic interference signal generated when the switching control signal is output by the switching transistor drive circuit; wherein the magnitude of the cancellation signal is equal to the magnitude of the electromagnetic interference signal.

[0013] Furthermore, the sampling module includes:

[0014] A first resistor has its first end connected to the reference ground of the switching transistor drive circuit, and its second end connected to the first end of the first capacitor; the third end of the sampling module is led out from between the second end of the first resistor and the first end of the first capacitor.

[0015] The second terminal of the first capacitor is grounded.

[0016] Furthermore, the circuit also includes:

[0017] A low-pass filter module is disposed between the third terminal of the sampling module and the processing chip.

[0018] Furthermore, the circuit also includes:

[0019] The second capacitor has its first end connected to the interference cancellation module and its second end grounded.

[0020] Furthermore, the processing chip is specifically used for:

[0021] Obtain the preset time difference between the cancellation signal and the electromagnetic interference signal;

[0022] The timing of the output of the cancellation signal is controlled according to the preset time difference.

[0023] Furthermore, the processing chip is also specifically used for:

[0024] The direction of the electromagnetic interference signal generated when the switching control signal is output by the switching transistor drive circuit is obtained;

[0025] The interference cancellation module is controlled to output a cancellation signal that is opposite in direction to the electromagnetic interference signal.

[0026] The present invention also provides an electrical device including the above-mentioned electromagnetic interference suppression circuit.

[0027] The present invention also provides an electromagnetic interference suppression method, applied to the above-mentioned electromagnetic interference suppression circuit, the method comprising:

[0028] Acquire the timing of the switch control signal output by the switch transistor drive circuit of the electrical equipment, as well as the direction of the electromagnetic interference signal generated when the switch transistor drive circuit outputs the switch control signal.

[0029] Acquire the timing of the switch control signal output by the switch transistor drive circuit of the electrical equipment, as well as the direction of the electromagnetic interference signal generated when the switch transistor drive circuit outputs the switch control signal.

[0030] The timing of the output of the cancellation signal of the electromagnetic interference suppression circuit is controlled according to the timing of the output switch control signal of the switch driving circuit, and the direction of the cancellation signal of the electromagnetic interference suppression circuit is controlled according to the direction of the electromagnetic interference signal.

[0031] Furthermore, the method also includes:

[0032] The magnitude of the cancellation signal is controlled according to the magnitude of the electromagnetic interference signal generated when the switching control signal is output by the switching transistor drive circuit; wherein, the magnitude of the cancellation signal is equal to the magnitude of the electromagnetic interference signal.

[0033] Furthermore, controlling the output timing of the cancellation signal of the electromagnetic interference suppression circuit based on the timing of the output switching control signal of the switching transistor drive circuit includes:

[0034] Obtain the preset time difference between the cancellation signal and the electromagnetic interference signal;

[0035] The timing of the output of the cancellation signal is controlled according to the preset time difference.

[0036] Further, controlling the direction of the cancellation signal of the electromagnetic interference suppression circuit according to the direction of the electromagnetic interference signal includes:

[0037] The control interference cancellation module outputs a cancellation signal in the opposite direction to the electromagnetic interference signal.

[0038] The present invention also provides a computer-readable storage medium having a computer program stored thereon, wherein the program, when executed by a processor, implements the above-described electromagnetic interference suppression method.

[0039] By applying the technical solution of this invention, the processing chip controls the timing of the output of the cancellation signal according to the timing of the switch control signal output by the switch driving circuit, and controls the direction of the cancellation signal according to the direction of the electromagnetic interference signal generated when the switch driving circuit outputs the switch control signal. This enables active interference suppression based on the direction and timing of the electromagnetic interference signal. Compared with passive filtering, this invention is applicable to an unrestricted frequency range and can produce a good interference suppression effect on electromagnetic interference signals of different frequencies. Attached Figure Description

[0040] Figure 1 This is a structural diagram of an electromagnetic interference suppression circuit according to an embodiment of the present invention;

[0041] Figure 2 This is a structural diagram of another electromagnetic interference suppression circuit according to an embodiment of the present invention;

[0042] Figure 3 The direction of the canceling current in one embodiment of the present invention;

[0043] Figure 4 This refers to the direction of the canceling current in another case according to an embodiment of the present invention;

[0044] Figure 5 This is a flowchart of an electromagnetic interference suppression method according to an embodiment of the present invention;

[0045] Figure 6 This is a flowchart of another electromagnetic interference suppression method according to an embodiment of the present invention. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0047] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms, and “multiple” generally includes at least two unless the context clearly indicates otherwise.

[0048] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0049] It should be understood that although the terms "first," "second," etc., may be used to describe capacitors in the embodiments of the present invention, these capacitors should not be limited to these terms. These terms are only used to distinguish capacitors that are placed in different locations to perform different functions. For example, without departing from the scope of the embodiments of the present invention, a first capacitor may also be referred to as a second capacitor, and similarly, a second capacitor may also be referred to as a first capacitor.

[0050] Depending on the context, the words “if” or “suppose” as used here can be interpreted as “when” or “in response to determination” or “in response to detection.” Similarly, depending on the context, the phrases “if determination” or “if detection (of the stated condition or event)” can be interpreted as “when determination” or “in response to determination” or “when detection (of the stated condition or event)” or “in response to detection (of the stated condition or event).”

[0051] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or device that includes said element.

[0052] The optional embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0053] Example 1

[0054] This embodiment provides an electromagnetic interference suppression circuit, applied in electrical equipment with a switching transistor drive circuit. In this embodiment, the switching transistor drive circuit can be located in a controller, wherein the switching transistor drive circuit is connected to the switching transistor and is used to output a switching control signal to control the switching on and off of the switching transistor. Figure 1 This is a structural diagram of an electromagnetic interference suppression circuit according to an embodiment of the present invention, such as... Figure 1 As shown, the electromagnetic interference suppression circuit described above includes:

[0055] Interference cancellation module 10 is grounded and is used to output a cancellation signal to cancel the electromagnetic interference signal generated by the switching transistor drive circuit. Processing chip 20 is connected to interference cancellation module 10 and is used to control the output timing of the cancellation signal according to the timing of the switching control signal output by the switching transistor drive circuit, and to control the direction of the cancellation signal according to the direction of the electromagnetic interference signal generated when the switching transistor drive circuit outputs the switching control signal. In this embodiment, the cancellation signal refers to the cancellation current.

[0056] It should be noted that in this embodiment, the timing of the output of the cancellation signal must be synchronized with the timing of the output switch control signal, or the time difference between the two must be within a preset range; otherwise, the cancellation signal will lose its cancellation effect. Furthermore, the direction of the cancellation signal must be opposite to the direction of the interference signal to achieve the cancellation effect. Therefore, it is necessary to control the output timing of the cancellation signal according to the timing of the output switch control signal of the switch transistor drive circuit, and to control the direction of the cancellation signal according to the direction of the electromagnetic interference signal generated when the switch transistor drive circuit outputs the switch control signal. When the output timing and direction of the cancellation signal meet the above requirements, the magnitude of the cancellation signal can be equal to or unequal to the magnitude of the electromagnetic interference signal. If the magnitude of the cancellation signal is equal to the magnitude of the electromagnetic interference signal, it can completely suppress the electromagnetic interference signal. If the magnitude of the cancellation signal is unequal to the magnitude of the electromagnetic interference signal, although it cannot completely suppress the electromagnetic interference signal, it can still reduce the intensity of the interference signal.

[0057] In this embodiment, the processing chip 20 of the electromagnetic interference suppression circuit can control the output timing of the cancellation signal according to the timing of the switch control signal output by the switch driving circuit, and control the direction of the cancellation signal according to the direction of the electromagnetic interference signal generated when the switch driving circuit outputs the switch control signal. It can achieve active interference suppression based on the direction and timing of the electromagnetic interference signal. Compared with the passive electromagnetic interference suppression scheme in the prior art, the frequency range of the technical solution in this embodiment is not limited, and it can produce a better interference suppression effect for electromagnetic interference signals of different frequencies.

[0058] Example 2

[0059] This embodiment provides another electromagnetic interference suppression circuit. Figure 2 This is a schematic diagram of another electromagnetic interference suppression circuit according to an embodiment of the present invention. To obtain the direction of the electromagnetic interference signal generated when the switching control signal is output by the switching transistor drive circuit, the direction of the cancellation signal is controlled, such as... Figure 2 As shown, the electromagnetic interference suppression circuit also includes:

[0060] The sampling module 30 has its first terminal connected to the reference ground of the switching transistor drive circuit, its second terminal grounded, and its third terminal connected to the processing chip 20. It is used to detect the direction of the electromagnetic interference signal generated by the switching transistor drive circuit and send it to the processing chip 20. Figure 2 As shown, a parasitic capacitance Ca is generated between the reference ground terminal of the switching transistor drive circuit and the earth. It should be noted that grounding refers to connection to the earth level network, while the reference ground terminal (i.e., floating ground terminal) of the switching transistor drive circuit represents the reference ground plane of the high-voltage or low-voltage part of the switching transistor drive circuit, which is different from the connection to the earth level network.

[0061] In order to completely cancel out electromagnetic interference, the sampling module 30 is also used to: detect the magnitude of the electromagnetic interference signal generated when the switching control signal is output by the switching transistor drive circuit; the processing chip 20 is also used to: control the magnitude of the cancellation signal according to the magnitude of the electromagnetic interference signal; wherein, the magnitude of the cancellation signal is equal to the magnitude of the electromagnetic interference signal to obtain the best interference suppression effect.

[0062] To accurately detect the direction of electromagnetic interference signals generated by the switching transistor drive circuit, the sampling module 30 includes: a first resistor R1, whose first end is connected to the reference ground of the switching transistor drive circuit, and whose second end is connected to the first end of a first capacitor C1; and the second end of the first capacitor C1 is grounded. In specific implementation, a third terminal of the sampling module 30 is led out from between the second end of the first resistor R1 and the first end of the first capacitor C1 to collect the voltage across the first resistor R1.

[0063] Interference current I, sampling voltage V, and resistance R of the first resistor R1 The relationship between them satisfies the formula: I = V / R R1 The sampling voltage V and the resistance value R of the first resistor are... R1 Substituting into the above formula, the magnitude of the interference current I can be calculated. The direction of the interference current I can be obtained based on the direction of the sampling voltage V. The direction of the interference current I is the same as the direction of the sampling voltage V. If the value of the sampling voltage V is positive, the direction of the interference current I is positive, that is, it flows from the reference ground terminal of the switching transistor drive circuit to the ground terminal. If the value of the sampling voltage V is negative, the direction of the interference current I is negative, that is, it flows from the ground terminal to the reference ground terminal of the switching transistor drive circuit.

[0064] Since the sampling module 30 is essentially a high-pass filter circuit, which has already limited the lowest frequency of the electromagnetic interference signal, the subsequent sampling signal only needs to undergo low-pass filtering. Therefore, as Figure 2As shown, the circuit also includes a low-pass filter module 40, disposed between the third terminal of the sampling module 30 and the processing chip 20, used to filter out high-frequency signals and allow low-frequency signals to pass. In this embodiment of the electromagnetic interference suppression circuit, since the sampling module 30 can already perform the function of a high-pass filter, only a low-pass filter needs to be set, thus reducing the size of the filter.

[0065] To assist in the release and storage of electrical energy, the electromagnetic interference suppression circuit also includes a second capacitor C2, whose first end is connected to the interference cancellation module 10 and whose second end is grounded.

[0066] By using the aforementioned capacitors and resistors, the space occupied by the electromagnetic interference suppression circuit can be reduced, and costs can be saved.

[0067] In order to accurately control the timing of the output of the cancellation signal by the interference cancellation module 10 to obtain the optimal cancellation effect, the processing chip 20 is specifically used to: obtain the preset time difference between the cancellation signal and the electromagnetic interference signal; and control the output timing of the cancellation signal according to the preset time difference.

[0068] Specifically, the aforementioned preset time difference can be a positive value, in which case the cancellation signal lags behind the electromagnetic interference signal output; the aforementioned preset time difference can also be a negative value, in which case the cancellation signal is output ahead of the electromagnetic interference signal output; the aforementioned preset time difference can also be 0, in which case the cancellation signal and the electromagnetic interference signal are output synchronously. The specific value of the preset time difference can be obtained through experiments.

[0069] To further improve the interference suppression effect, the processing chip 20 is also specifically used to: obtain the direction of the electromagnetic interference signal generated by the switching transistor drive circuit; and control the interference cancellation module to output a cancellation signal with the opposite direction to the electromagnetic interference signal generated by the switching transistor drive circuit.

[0070] The working principle of the electromagnetic interference suppression circuit in this embodiment is as follows:

[0071] First, obtain the timing of the switch control signal output by the switch tube drive circuit of the electrical equipment.

[0072] Taking frequency converters as an example, most current frequency converter topologies are "AC-DC-AC" topologies. This involves rectifying AC power to DC power, then inverting the DC power back to AC power. Some topologies include both conversions, while others only include one. Another type of topology is the "AC-AC" frequency converter, which directly converts AC power to AC power without requiring intermediate control steps.

[0073] In the above topologies, there are many control schemes. For example, in AC-DC rectification, there are bridgeless power correction circuit control schemes, interleaved power correction circuit control schemes, H-bridge power correction circuit control schemes, and so on. DC-AC inverter topologies also include many control schemes, such as H-bridge inverter control schemes and three-way full-bridge inverter control schemes. However, regardless of the topology and control scheme, switching noise is generated during the operation of the switching transistors, resulting in electromagnetic interference (EMI). Therefore, by applying a reverse cancellation signal to the switching transistor drive circuit during the same time period when the switching transistor is on and off, the EMI generated by the switching transistor drive circuit can be reduced, effectively mitigating the EMI interference signal from the switching transistor drive circuit to the outside world.

[0074] In this embodiment, the timing of the reverse cancellation signal applied is based on the timing of the switching control signal output by the switching transistor drive circuit of the electrical equipment. Compared with the timing of the switching control signal output by the switching transistor drive circuit, the timing of the reverse cancellation signal applied may be ahead of a set time, behind a set time, or synchronized. The specific timing needs to be determined after debugging and verifying the filtering effect according to the specific application of the switching transistor drive circuit.

[0075] Second, sample the electromagnetic interference signal.

[0076] The direction of the applied cancellation signal needs to be determined based on the electromagnetic interference signal generated by the switching transistor drive circuit. When sampling the electromagnetic interference signal, the battery interference signal is sampled first, and then low-pass filtered.

[0077] As mentioned above Figure 2 As shown, the sampling module 30 is equivalent to a high-pass filter circuit. The specific values ​​of the capacitance of the first capacitor C1 and the resistance of the first resistor R1 in this sampling circuit need to be set according to the sampling frequency band. It is recommended to select high-precision components to improve the sampling accuracy.

[0078] The formula for calculating the cutoff frequency is: Among them, R R1 Let C be the resistance value of the first resistor R1. C1 Since the capacitance of the first capacitor C1 needs to compensate for electromagnetic interference signals rather than working electrical signals, its cutoff frequency should be much higher than the working frequency of the switching transistor drive circuit itself. Therefore, the component parameters can be adjusted according to the actual effect when selecting them.

[0079] After obtaining the sampled voltage across the first resistor R1, the sampled voltage signal needs further filtering. Since the sampling module 30 is equivalent to a high-pass filter circuit, which has already limited the lowest frequency of the electromagnetic interference signal, further low-pass filtering is required. Taking electromagnetic interference testing of household appliances as an example, the typical frequency band of conducted interference is 150kHz-30MHz, and the frequency band of radiated interference is 30MHz-300MHz. Therefore, the upper limit frequency of the low-pass filter should be set above 300MHz, and the specific setting should be adjusted according to the actual debugging situation. After completing the low-pass filtering, the signal can be amplified or reduced according to the operating voltage requirements of the processing chip 20, and then the obtained signal is sent to the processing chip 20 for processing.

[0080] Third, data processing is performed through processing chips.

[0081] The processing chip, based on the timing of the switch control signal output by the switch drive circuit and the direction of the sampling voltage obtained by the sampling module 30, considers the interference current I, the sampling voltage V, and the resistance value R of the first resistor. R1 The relationship between them satisfies the formula: I = V / R R1 The sampling voltage V and the resistance value R of the first resistor are... R1 Substituting into the above formula, the magnitude of the interference current I can be calculated. The direction of the interference current I can be obtained based on the direction of the sampling voltage V. The direction of the interference current I is the same as the direction of the sampling voltage V. If the value of the sampling voltage V is positive, the direction of the interference current I is positive, meaning it flows from the reference ground terminal of the switching transistor drive circuit to the ground terminal; if the value of the sampling voltage V is negative, the direction of the interference current I is negative, meaning it flows from the ground terminal to the reference ground terminal of the switching transistor drive circuit. Based on the direction of this interference signal, it can be determined whether the interference signal flows from the reference ground terminal of the switching transistor drive circuit to the ground terminal or from the ground terminal to the reference ground terminal of the switching transistor drive circuit. Then, different energy compensation or discharge methods can be applied based on these two states, i.e., controlling the direction of the cancellation current.

[0082] Figure 3 For example, the direction of the canceling current in one case according to an embodiment of the present invention, such as Figure 3 As shown, if the direction of the electromagnetic interference signal is from the reference ground terminal of the switching transistor drive circuit to the ground, then the direction of the cancellation signal output by the interference cancellation module 10 is from the ground to the interference cancellation module 10. That is, the electromagnetic interference signal is discharged to the ground through the interference cancellation module 10. Since the electromagnetic interference signal flows from the reference ground terminal of the switching transistor drive circuit to the ground, the ground terminal acquires a charge. In order to maintain the charge stability on the ground level network, it is necessary to discharge the charge acquired by the ground terminal in order to cancel the electromagnetic interference signal.

[0083] Figure 4For another case of the offsetting current according to an embodiment of the present invention, such as Figure 4 As shown, Figure 4 As shown, if the electromagnetic interference signal flows from the ground to the reference ground of the switching transistor drive circuit, that is, the electromagnetic interference signal flows out from the ground, in order to maintain the charge stability of the ground level network, it is necessary to replenish the charge on the ground in order to cancel the electromagnetic interference signal. At this time, the direction of the cancellation signal output by the interference cancellation module 10 is from the interference cancellation module 10 to the ground, that is, the interference cancellation module 10 injects charge into the ground.

[0084] In order to perform charge injection or discharge, the processing chip 20 needs to calculate the direction of the electromagnetic interference signal, and then output a control signal to the interference cancellation module 10. The control signal carries the direction of the cancellation current output by the interference cancellation module 10, or carries both the direction and magnitude of the cancellation current.

[0085] Example 3

[0086] This embodiment provides an electrical device that includes a switching transistor drive circuit and the electromagnetic interference suppression circuit described in the above embodiment. This enables the suppression of interference signals from the switching transistor drive circuit. Regardless of the frequency range, active suppression of interference signals can be achieved to obtain a better interference suppression effect, thereby improving the stability of the electrical device.

[0087] Example 4

[0088] This embodiment provides an electromagnetic interference suppression method, applied to the electromagnetic interference suppression circuit of the above embodiment. Figure 5 Here is a flowchart of an electromagnetic interference suppression method according to an embodiment of the present invention, such as... Figure 5 As shown, the method includes:

[0089] S101, obtain the timing of the switch control signal output by the switch drive circuit of the electrical equipment and the direction of the electromagnetic interference signal generated when the switch drive circuit outputs the switch control signal.

[0090] S102 controls the timing of the output of the cancellation signal according to the timing of the switch control signal output by the switch drive circuit, and controls the direction of the cancellation signal according to the direction of the electromagnetic interference signal generated when the switch drive circuit outputs the switch control signal.

[0091] In practical implementation, the direction of the electromagnetic interference signal generated when the switching control signal is output by the switching transistor drive circuit is detected by a sampling module. The sampling module includes: a first resistor, the first end of which is connected to the reference ground of the switching transistor drive circuit, and the second end of which is connected to the first end of a first capacitor; and a first capacitor, the second end of which is grounded. In practical implementation, a third terminal of the sampling module is led out from between the second end of the first resistor and the first end of the first capacitor to collect the voltage across the first resistor.

[0092] Interference current I, sampling voltage V, and resistance R of the first resistor R1 The relationship between them satisfies the formula: I = V / R R1 The sampling voltage V and the resistance value R of the first resistor are... R1 Substituting into the above formula, the magnitude of the interference current I can be calculated. The direction of the interference current I can be obtained based on the direction of the sampling voltage V. The direction of the interference current I is the same as the direction of the sampling voltage V. If the value of the sampling voltage V is positive, the direction of the interference current I is positive, that is, it flows from the reference ground terminal of the switching transistor drive circuit to the ground terminal. If the value of the sampling voltage V is negative, the direction of the interference current I is negative, that is, it flows from the ground terminal to the reference ground terminal of the switching transistor drive circuit.

[0093] The electromagnetic interference suppression method of this embodiment controls the timing of the output of the cancellation signal by obtaining the timing of the switch control signal output by the switch control circuit of the power device, and controls the direction of the cancellation signal according to the direction of the electromagnetic interference signal generated when the switch control circuit outputs the switch control signal. It can achieve active interference suppression based on the direction of the electromagnetic interference signal and the timing of its generation. Compared with passive filtering, the frequency range of the electromagnetic interference suppression method of this embodiment is not limited, and it can produce a good interference suppression effect for electromagnetic interference signals of different frequencies.

[0094] Example 5

[0095] This embodiment provides another electromagnetic interference suppression method. In order to completely cancel the electromagnetic interference, the electromagnetic interference suppression method of this embodiment further includes: controlling the magnitude of the cancellation signal according to the magnitude of the electromagnetic interference signal generated when the switching control signal is output by the switching transistor drive circuit; wherein, the magnitude of the cancellation signal is equal to the magnitude of the electromagnetic interference signal to obtain the best interference suppression effect.

[0096] In order to accurately control the timing of the output cancellation signal and obtain the optimal cancellation effect, the output timing of the cancellation signal is controlled according to the timing of the switch control signal output by the switch drive circuit, including: obtaining the preset time difference between the cancellation signal and the electromagnetic interference signal; and controlling the output timing of the cancellation signal according to the preset time difference.

[0097] Specifically, the aforementioned preset time difference can be a positive value, in which case the cancellation signal lags behind the electromagnetic interference signal output; the aforementioned preset time difference can also be a negative value, in which case the cancellation signal outputs ahead of the electromagnetic interference signal output; the aforementioned preset time difference can also be 0, in which case the cancellation signal is synchronized with the electromagnetic interference signal output. The specific value of the preset time difference can be obtained through experiments.

[0098] To further improve the interference suppression effect, in this embodiment, the direction of the cancellation signal is controlled according to the direction of the electromagnetic interference signal generated when the switching control signal is output by the switching transistor drive circuit, including: controlling the interference cancellation module to output a cancellation signal with the opposite direction to the electromagnetic interference signal.

[0099] Figure 6 Here is a flowchart of another electromagnetic interference suppression method according to an embodiment of the present invention, such as... Figure 6 As shown, the electromagnetic interference suppression method includes:

[0100] S1. Determine whether the switching transistor drive circuit outputs a switching control signal. If not, repeat step S1. If yes, execute step S2.

[0101] The timing of the interference cancellation module outputting the cancellation signal depends on the timing of the switching control signal output by the switching transistor drive circuit. If the switching transistor drive circuit does not output a switching control signal, it means that the switching transistor drive circuit is not working, and the interference cancellation module is not working. If the switching transistor drive circuit outputs a switching control signal, it means that the switching transistor drive circuit has started working and will generate electromagnetic interference signals. At this time, the interference cancellation module is controlled to output the cancellation signal synchronously.

[0102] S2, obtain the direction of the electromagnetic interference signal.

[0103] S3. Determine whether the direction of the electromagnetic interference signal is from the reference ground terminal of the switching transistor drive circuit to the ground. If yes, proceed to step S4; otherwise, proceed to step S5.

[0104] S4, control the interference cancellation module to output a negative cancellation current to the ground, which is equal in magnitude to the electromagnetic interference signal, to discharge the charge on the ground, and then return to step S2.

[0105] S5, control the interference cancellation module to output a positive cancellation current to the ground that is equal in magnitude to the electromagnetic interference signal, inject charge into the ground, and then return to step S2.

[0106] Subsequently, the cancellation current is continuously adjusted based on the sampled voltage signal across the first resistor. If the sampled voltage signal is positive, it indicates that the electromagnetic interference signal flows from the reference ground terminal of the switching transistor drive circuit to the ground, so charge is discharged to the ground. If the sampled voltage signal is negative, it indicates that the electromagnetic interference signal flows from the ground to the reference ground of the switching transistor drive circuit, so charge is injected to the ground. If the sampled voltage signal value increases, the cancellation current is increased; if the sampled voltage signal value decreases, the cancellation current is decreased, ultimately achieving a dynamic equilibrium state where the electromagnetic interference signal value of the first resistor is 0.

[0107] Example 6

[0108] This embodiment provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the above-described electromagnetic interference suppression method.

[0109] The circuit embodiments described above are merely illustrative. The modules described as separate components may or may not be physically separate. The components shown as modules may or may not be physical modules; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0110] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0111] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An electromagnetic interference suppression circuit, applied to electrical equipment with a switching transistor drive circuit, characterized in that, The circuit includes: An interference cancellation module, grounded, is used to output a cancellation signal to cancel the electromagnetic interference signal generated when the switching control signal is output by the switching transistor drive circuit of the electrical equipment. The processing chip, connected to the interference cancellation module, is used to control the output timing of the cancellation signal according to the timing of the switch control signal output by the switch drive circuit, and to control the direction of the cancellation signal according to the direction of the electromagnetic interference signal. The processing chip is further configured to: control the magnitude of the cancellation signal according to the magnitude of the electromagnetic interference signal; wherein the magnitude of the cancellation signal is equal to the magnitude of the electromagnetic interference signal; The processing chip is also specifically used for: Obtain the preset time difference between the cancellation signal and the electromagnetic interference signal; The timing of the output of the cancellation signal is controlled according to the preset time difference; The processing chip is also specifically used for: The direction of the electromagnetic interference signal generated when the switching control signal is output by the switching transistor drive circuit is obtained; The interference cancellation module is controlled to output a cancellation signal in the opposite direction to the electromagnetic interference signal.

2. The circuit according to claim 1, characterized in that, The circuit also includes: The sampling module has its first end connected to the reference ground of the switching transistor drive circuit, its second end grounded, and its third end connected to the processing chip. It is used to detect the direction of the electromagnetic interference signal generated when the switching transistor drive circuit outputs the switching control signal.

3. The circuit according to claim 2, characterized in that, The sampling module is also used to detect the magnitude of the electromagnetic interference signal generated when the switching control signal is output by the switching transistor drive circuit.

4. The circuit according to claim 2, characterized in that, The sampling module includes: A first resistor has its first end connected to the reference ground of the switching transistor drive circuit, and its second end connected to the first end of the first capacitor; the third end of the sampling module is led out from between the second end of the first resistor and the first end of the first capacitor. The second terminal of the first capacitor is grounded.

5. The circuit according to claim 4, characterized in that, The circuit also includes: A low-pass filter module is disposed between the third terminal of the sampling module and the processing chip.

6. The circuit according to claim 1, characterized in that, The circuit also includes: The second capacitor has its first end connected to the interference cancellation module and its second end grounded.

7. An electrical appliance, characterized in that, The electromagnetic interference suppression circuit includes any one of claims 1 to 6.

8. An electromagnetic interference suppression method, applied to the electromagnetic interference suppression circuit according to any one of claims 1 to 6, characterized in that, The method includes: Acquire the timing of the switch control signal output by the switch transistor drive circuit of the electrical equipment, as well as the direction of the electromagnetic interference signal generated when the switch transistor drive circuit outputs the switch control signal. The timing of the output of the cancellation signal of the electromagnetic interference suppression circuit is controlled according to the timing of the output of the switching control signal of the switching transistor drive circuit, and the direction of the cancellation signal of the electromagnetic interference suppression circuit is controlled according to the direction of the electromagnetic interference signal. The method further includes: The magnitude of the cancellation signal is controlled according to the magnitude of the electromagnetic interference signal generated when the switching control signal is output by the switching transistor drive circuit; wherein, the magnitude of the cancellation signal is equal to the magnitude of the electromagnetic interference signal; The timing of the output of the cancellation signal of the electromagnetic interference suppression circuit is controlled according to the timing of the output switching control signal of the switching transistor drive circuit, including: Obtain the preset time difference between the cancellation signal and the electromagnetic interference signal; The timing of the output of the cancellation signal is controlled according to the preset time difference; Controlling the direction of the cancellation signal of the electromagnetic interference suppression circuit according to the direction of the electromagnetic interference signal includes: controlling the interference cancellation module to output a cancellation signal opposite to the direction of the electromagnetic interference signal.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the method as described in claim 8.

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