Circuit for increasing the inductance of a high-current inductor
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- HK OCEANCOMM TECH CO LTD
- Filing Date
- 2024-08-29
- Publication Date
- 2026-07-30
Smart Images
Figure 0007897612000001 
Figure 0007897612000002 
Figure 0007897612000003
Abstract
Description
[Technical Field]
[0001] This invention relates to key components required for filters that improve power line communication (PLC) or reduce EMI. [Background technology]
[0002] Power line communication has been widely used in many fields since the late 1990s, including the HomePlug AV standard developed by the HPA (HomePlug Powerline Alliance), G3-PLC (Generation 3rd Power Line Communication), and HPLC (High-speed PLC). Power grids typically have problems such as high noise and low impedance that change over time, resulting in generally poor communication quality. These problems can be solved by installing a low-pass filter (or isolator) in front of the power consumption unit (power consumption side) (including the modem itself), as shown in Figure 1A. The 3dB low-pass frequency conversion point of this low-pass filter is much lower than the communication signal, blocking the communication signal without affecting the power supply and separating the power line into two segments (one for transmission and the other for consumption). The communication signal from the modem communication module (communication unit) passes through a coupler, bypassing this low-pass filter and being input to the power transmission side of the power line. As a result, in the frequency band used by the communication module's communication signals, time-varying noise and time-varying impedance are isolated on the power consumption side, and the power transmission side becomes a transmission medium with stable impedance and low noise, significantly improving communication efficiency.
[0003] However, since large currents generally flow through power transmission lines, inductors (used in isolators) that can handle high currents require large magnetic cores, resulting in high costs and large volume, making installation difficult. Figure 1B is a schematic diagram of a second-order low-pass filter, which is the simplest isolator. The larger the inductance value, the better the isolation effect, but the larger the volume of the inductor and the higher the cost. [Overview of the project]
[0004] The present invention provides a circuit for increasing the inductance of a high-current inductor in power line communications. In the circuit, a coupler is used to sense the voltage across the main inductor, and the associated voltage (aV, where a is the coupling coefficient, which is usually a constant; if a large capacitor or short circuit is used for coupling, a is equal to 1) is coupled to a current generator, and the current of the current generator is coupled to the main inductor. The purpose of the current generator is to duplicate one or more associated currents (in phase close to the actual current flowing through the inductor) and to pass this current through the main inductor to suppress the current driven by the signal itself. This makes the inductance value of the main inductor appear amplified, resulting in the effect of a large inductance. [Brief explanation of the drawing]
[0005] [Figure 1A] This document presents conventional technologies for improving PLC communication. [Figure 1B] This shows a commonly used second-order low-pass filter circuit. [Figure 2] Figures 2A to 2D show schematic diagrams of several embodiments of the present invention. [Figure 3] Figures 3A and 3B show schematic diagrams of embodiments of the present invention. [Figure 4] Figures 4A and 4B show schematic diagrams illustrating how the input current is reduced by the flow of a duplicated current through the transformer. [Figure 5A] This circuit uses a differential inverting linear driver and a 1:1 transformer to generate a large inductance across the signal frequency band. [Figure 5B] Figure 2D is a schematic diagram of another embodiment of the current generator 202. [Figure 6] This circuit uses a differential inverting linear driver and a 1:M transformer to generate a large inductance across the signal frequency band. [Figure 7] This invention demonstrates a method for stably mass-producing inductance 100 times greater by combining conventional inventions with the circuit of the present invention. [Figure 8] This demonstrates a method for stably mass-producing inductances with 100 times the normal amount by combining two transformers. [Figure 9A] A schematic diagram of another embodiment of the current generator 202 is shown. [Figure 9B] A schematic diagram of the circuit of the present invention in one embodiment is shown. [Figure 10] Figures 10A and 10B show schematic diagrams of the prior art. [Figure 11] Figures 11A to 10C show schematic diagrams of the prior art. [Figure 12] A schematic diagram of one embodiment of the present invention is shown. [Figure 13] A schematic diagram of one embodiment of the present invention is shown. [Figure 14] A schematic diagram of one embodiment of the present invention is shown. [Figure 15] Figures 15A and 15B show schematic diagrams of one embodiment of the present invention. [Figure 16] A schematic diagram of one embodiment of the present invention is shown. [Figure 17] A schematic diagram of one embodiment of the present invention is shown. [Figure 18] A schematic diagram of one embodiment of the present invention is shown. [Figure 19] A schematic diagram of one embodiment of the present invention is shown. [Figure 20] A schematic diagram of one embodiment of the present invention is shown. [Modes for carrying out the invention]
[0006] The present invention discloses a component that has a low inductance value at low frequencies for transmitting large currents and a high inductance value in a high-frequency communication signal band, and can meet the requirements of an isolator without requiring a large magnetic core. As shown in the schematic diagram of FIG. 2A, FIG. 2A shows a circuit 200A of a large current inductor that can be used to improve power line communication. Circuit 200A includes a main inductor L P , a coupler 201, and a current generator 202. A first current I in related to the communication signal flows through the main inductor L P to generate a voltage V related to the communication signal. The main inductor L P is located on the power line, and an alternating current (generally 50 or 60 Hz) or a direct current simultaneously flows through the main inductor L P .
[0007] The main inductor L P has both ends. When the current value I0 of the first current I in flows through the main inductor L P , it provides the voltage V. The coupler 201 senses the voltage V at both ends of the main inductor L P or a predetermined proportion of the voltage at both ends of the main inductor L P and is used to generate a coupled voltage aV. In this embodiment, a is the coupling coefficient. The current generator 202 is coupled to the coupler 201. The current generator 202 generates a second current I + based on the coupled voltage aV received from the coupler 201 or another coupler. The current generator 202 couples the second current I + to the main inductor L P . Finally, the second current I - returns to the coupler 201 and then returns to the current generator 202. The output impedance of the current generator 202 needs to be a high impedance.
[0008] The purpose of the current generator 202 is to replicate the first current I in to generate a second current I + . The phase and magnitude of the second current I + are the same as those of the first current I PThe first current I flowing through in Because it is close to, the second current I + The main inductor L P By allowing it to flow, the first current I is driven by the communication signal of circuit 200A itself. in Suppresses the first current I in The main inductor L is generated by the communication signal source. P This is the current flowing through it, and its value is I0.
[0009] In other words, circuit 200A is connected to the main inductor L by coupler 201. P The voltage V across the terminals of the main inductor L is sensed, and the associated voltage aV is coupled to the current generator 202. The current generated by the current generator 202 is then used to power the main inductor L. P Returning to the previous section, generally, the coupler 201 has a high-pass filtering function, its main purpose being to remove low-frequency power waves, the simplest way of doing this is to connect a capacitor in series. The purpose of the current generator 202 is to generate the first current I in One or more second currents related to I + The goal is to duplicate it. That is, the second current I + The phase and magnitude of the main inductor L are actually P The first current I flowing through in Because it is close to, the second current I + The main inductor L P By passing through it, the first current I is driven by the signal itself. in It can be suppressed.
[0010] Furthermore, as shown in the schematic diagrams of Figures 2B and 2C, in circuits 200B and 200C, the second current I + This can be passed through the coil of another inductor L. The coil of this inductor L is the main inductor L P It is connected in series with the coil and wound on the same magnetic core. Inductor L is coupler 201, main inductor L P It is connected in parallel between the transmitting and receiving sides, causing a change in magnetic flux within the magnetic core and suppressing the current flowing through the original inductor (low-frequency power supply current is the main inductor L). P Only the main inductor L flows through it.P This is the first current I related to the communication signal. in The main inductor L is used to provide AC signals. P The wire around which it is wound is a wire with a large diameter. However, in the schematic diagrams of Figures 2B and 2C, the newly wound inductor L has a first current I in Second current I to suppress + Since only current flows, the inductor L is the main inductor L P It can be wound with wire of a smaller diameter than the main inductor L. In other words, since only the communication signal current flows through the coil of inductor L, the wire diameter of the coil of inductor L is smaller than that of the main inductor L. P The wire diameter becomes smaller than that of the coil. By changing the winding of the inductor L, the value of the input current can be changed, for example, the second current I in Figure 2B. + (1st current I in The suppression current that suppresses this is the second current I shown in Figure 2A. + If it is smaller, the first current I in The same effect of suppressing is obtained. In this embodiment, the coil of the inductor L is the main inductor L P It is coupled to a predetermined position within the coil, that is, the coil of the inductor L is the main inductor L P The position where it is coupled to the coil is the main inductor L P It is not the endpoint. In the case of a communication signal source, the first current I in A decrease in the second current I is equivalent to an increase in the inductance value of the main inductor. + The magnetic flux change within the magnetic core generated by this can achieve the effect of increasing the inductance value. In this embodiment, the coupler 201 is the main inductor L P The circuit senses a predetermined ratio of voltage V' across the terminals and generates a coupling voltage aV'. The simplest coupling circuit requires only two capacitors C (as shown in Figure 2D), and since low-voltage capacitors are relatively inexpensive, such circuits are suitable for low-voltage circuits.
[0011] As shown in the schematic diagram in Figure 3A, the secondary inductor L of circuit 300A S The coil is the main inductor LP It is isolated from the coil. The first current I related to the communication signal in The main inductor L P The current flows through the main inductor L, generating a voltage V related to the communication signal. P It is located on the power line, and the main inductor L P A current of alternating current (generally 50 or 60 Hz) or direct current flows through it simultaneously. Secondary inductor L S It is coupled to coupler 201, meaning that in circuit 300A, this second current I + The original main inductor L P The magnetic flux can also be passed through another or more coils wound around the magnetic core. These coils generate magnetic flux changes within the magnetic core to form the main inductor L. P The first current I flowing through in As long as it is suppressed, the main inductor L P It is separated from the coil (equivalent to a transformer). In this embodiment, the main inductor L P The coil and secondary inductor L S The ratio of the number of turns in the coil is 1:M, where M is a constant. The secondary inductor L S The main inductor L P The voltage across the terminals or the main inductor L P Based on a predetermined ratio of voltage across both ends, the voltage MV is generated. Coupler 201 generates the voltage MV based on the secondary inductor L S The voltage across both ends or the secondary inductor L S The current generator 202 senses a predetermined ratio of voltage across both ends and generates a coupling voltage aMV. The current generator 202 generates current I according to the coupling voltage aMV received from coupler 201 or another coupler. + The current generator 202 generates current I in the same coupler 202 or another coupler. + By coupling them, the main inductor L P This generates a back electromotive force. The purpose of the current generator 202 is to generate the second current I + Generates the main inductor L P First current I in the magnetic core in The magnetic field generated by is replicated, and the first current I is driven by the communication signal of circuit 300A itself. inis to suppress it. That is, instead of the primary inductor L P it is the secondary inductor L S through which the second current I + flows, thereby suppressing the first current I P flowing through the primary inductor L in and isolating the high voltage on the power transmission side from entering the coupler 201 by the transformer composed of the primary inductor L P and the secondary inductor L S . In the case of an AC power grid, the voltage of the current generator 202 at 50 / 60 Hz is relatively high and may exceed 300 volts. In this case, isolating the high voltage from entering the coupler 201 by the transformer can reduce costs. As shown in the schematic diagram of FIG. 3B, in the circuit 300B, the simplest coupler 201 uses one capacitor C. The impedance of this capacitor C can be ignored in the communication frequency band and can remove low-frequency AC signals. When the voltage drop generated by the low-frequency AC current in the primary coil is extremely small, this capacitor can also be omitted.
[0012] As shown in the schematic diagram of FIG. 4A, FIG. 4A shows a schematic diagram of the transformer in the embodiment of FIG. 3A. In this embodiment, a 1:1 transformer is used. When the current generator 202 does not generate current (when the current value I + of the second current I c generated by the current generator 202 = 0), the coil of the primary inductor L P is a pure inductor, and the voltage drops on both sides of the primary inductor L P are reflected at the other end of the transformer. As shown in the schematic diagram of FIG. 4B, as the main concept of suppressing the first current I in input from the power transmission side by the transformer, a magnetic field is generated in the transformer by the second current I + of the current generator 202, so that the voltage Vc generated by the change in magnetic flux on the secondary inductor L S is made close to the voltage V across the primary inductor L P (the voltage Vc will not be greater than the voltage V across both ends. Otherwise, oscillation will occur). Thereby, the primary inductor L PThis produces an effect equivalent to a higher inductance. In this circuit, the current generator 202 has a secondary inductor L in the low-frequency AC current frequency band (50 / 60 Hz). S Since no current is generated in the coil (coupler 201 removes low-frequency signals), and the output impedance of the current generator 202 is relatively high, the current generator 202 is equivalent to an open circuit. Therefore, at low frequencies, the transformer (main inductor L P and secondary inductor L S ) becomes a small inductor (when selecting an inductor, ensure that magnetic saturation does not occur when the maximum AC current flows), and as a result, it becomes a component with high inductance only at high frequencies (communication frequency band). The second current I generated by the current generator 202 + The main inductor L P As the reverse voltage induced approaches V, the first current I in It approaches zero.
[0013] The above concept can be implemented using various known circuits, and some examples are given below. As shown in the schematic diagram of Figure 5A, in circuit 500A, the main inductor L P The inductance value is L0, and the main inductor L P and secondary inductor L S1 The transformer is formed by the transformer, and the 500A circuit is powered by the transformer, with the main inductor L P The voltage V across the terminals can be extracted. In this embodiment, the current generator 202 of the circuit 500A is implemented by a differential linear driver, and the differential linear driver has another reference inductor L at its load terminal. S2 It drives the inductance L1, and the reference inductor L S2 The current flowing through it is I L1 Therefore, L1 / L0 = N, and the main inductor L P and secondary inductor L S1 The two have the same number of turns (i.e., the main inductor L P and secondary inductor L S1 (This is a 1:1 transformer) and the current generator 202 will have a current flowing through it I + Current value I = N × IL1 All that is needed is to duplicate it. In the ideal case, the first current I on the transmitting side at this time in As approaches zero, i.e., the equivalent inductance value increases significantly. In this embodiment, the differential linear driver has a first input terminal 1 and a second input terminal 2. The first input terminal 1 and the second input terminal 2 are connected to the secondary inductor L S1 It is coupled to the input and output terminals. The differential linear driver has a first output terminal Q1, a second output terminal Q2, a third output terminal Q3, and a fourth output terminal Q4, and the first output terminal Q1 and the fourth output terminal Q4 are connected to an inductor L as load terminals. S2 It is connected in series with the first input terminal 1 and the third output terminal Q3, which are connected in parallel with the coupler 201 (capacitor C in this embodiment), and the second output terminal Q2, which are connected in parallel with the second input terminal 2. A matching impedance Z exists between the first input terminal 1 and the coupler 201, and a matching impedance Z exists between the second input terminal 2 and the second output terminal Q2. The first input terminal 1 and the first output terminal Q1 are connected in parallel with the matching impedance Z, and the second input terminal 2 and the fourth output terminal Q4 are connected in parallel with the matching impedance Z. In this embodiment, in the communication frequency band, the impedance value of the matching impedance Z is much larger than ωL0 or ωL1. To avoid the generation of DC (due to the imperfect balance of the circuit itself) or low-frequency current of 50 / 60Hz in the differential linear driver, a reference inductor L is used as shown in the schematic diagram of Figure 5A. S2 A large capacitor C R It can be connected in series.
[0014] The current generator 202 includes one or more amplifiers and a reference inductor L S2 It has and can be used as a current replication circuit. The current replication circuit uses an amplifier to create a reference inductor L S2 Voltage V applied across the terminals L1 It operates with the reference inductor L S2 The voltage V across both ends L1 The main inductor L P It is proportional to the voltage V across its terminals. Therefore, the reference inductor LS2 Current I L1A current flows, and through the current replication circuit, the reference inductor L S2 Current I L1 The current I is proportional to the current I. + It is generated and output.
[0015] Similarly, circuit 500B in Figure 5B is a schematic diagram of another embodiment of the current generator 202 in Figure 2D. The current generator 202 is also implemented by a differential linear driver. The differential linear driver has another reference inductor L at its load terminal. S2 It drives the system, and its principle is as described above, so it will not be repeated here.
[0016] As shown in the schematic diagram of Figure 6, in circuit 600, in order to reduce the power loss of the linear driver, the power supply voltage V of the linear driver CC If (not shown) is greater than the signal source voltage, the number of turns of the wound inductor can be adjusted by M times, and in this case, if the feedback impedance of the linear driver is K times the input impedance (K is a constant), then L1 / L0 = M 2 The result is ×N × K. In a linear driver, the current I flowing through the secondary inductor or transformer is + Current value I = N × I L1 This replicates the signal, and in the ideal case, the main inductor L generated by the signal source is then... P The current value I0 flowing through it approaches zero.
[0017] Considering actual conditions such as temperature changes, time delays, and inaccuracies in component precision, it is difficult to easily mass-produce circuits by setting the equivalent inductance value to a high multiple to avoid oscillation. As shown in the schematic diagram of Figure 7, circuit 700 further includes a linear amplifier LNA placed between the power transmission side and the power consumption side. The linear amplifier LNA is coupled to transformers T2 and T3 on the power transmission side and power consumption side, respectively. The input terminals of the linear amplifier LNA are coupled to both ends of the secondary coil of transformer T2, and the input terminals of the linear amplifier LNA and both ends of the secondary coil of transformer T2 are coupled to input impedance M1Z, respectively. The output terminals of the linear amplifier LNA are coupled to both ends of the primary coil of transformer T3, and output impedance 0.9M2Z is connected in parallel between the output terminals and input terminals of the linear amplifier LNA, respectively. In circuit 700, the linear amplifier LNA controls the main inductor L P The voltage on the opposite side is 0.9M2V in To make it so (in the example in Figure 7, if the turns ratio of the coupling transformer T2 is 1:M1 (M1 is a constant), the ratio of input impedance to output impedance will be M1:0.9M2). Main inductor L P A low-pass filter 204 is connected behind it to remove noise from the power consumption side. The capacitive impedance (1 / ωC) of this low-pass filter 204 in the communication frequency band is equal to the inductor impedance (ωL) of the low-pass filter 204. f If it is much smaller than ), the main inductor L P The inductance value is L0, and the main inductor L P The voltage across both ends is 0.1V in , inductor L in the low-pass filter 204 f The voltage across both ends is 0.9V in This is the result. At this time, the main inductor L P The first current I flowing through in The current value I0 is only 0.1 times the original value, which is due to the main inductor L P This corresponds to a tenfold increase in the inductance value L0. Subsequently, the current generator 202 generates current I + When a change in magnetic flux is generated by outputting a current I + Current value Ic It also becomes 0.9 times the original insulating inductor (in the example in Figure 6, I + = 0.9 × N × I L1 In this case, the circuit can increase the average inductance value by 100 times, the actual value becomes approximately 50 to 200 times, and the circuit remains stable without oscillation.
[0018] As shown in the schematic diagram of Figure 8, in another embodiment of the circuit 800, there are two main inductors L P _1 and L P Use _2 (or a transformer) and two main inductors L P _1 and L P _2 (or transformer) each corresponds to the secondary inductor L S1 _1 and L S1 It has a main inductor L _2, couplers 201_1 and 201_2, and corresponding current generators 202_1 and 202_2. P _1 and L P The inductance values of _2 are L0 and L2, respectively. Main inductor L P Transformer _1 has a corresponding coupler 201_1 and a current generator 202_1, and a main inductor L P The transformer _2 has a corresponding coupler 201_2 and a current generator 202_2, and the coupler 201_2 generates current I2 + It has two forward output terminals, and one of the forward output terminals of coupler 201_2 is connected to the current I2 of coupler 201_1. + The forward output terminal of the 201_2 is connected to the secondary inductor L. S1 It is connected to the input terminal of _2. Note that coupler 201_2 is connected to the secondary inductor L S1 Coupler 201_2 is connected to the input terminal of _1, and the secondary inductor L S1 The secondary inductor L is coupled to the output terminal of _2. S1 The output terminal of _1 is the secondary inductor L S1 It is connected to the input terminal of _2, and the voltage between these two is V inThis is how it works. A filter capacitor C is connected in parallel to the power consumption side after circuit 800. The impedance of the filter capacitor C in the communication frequency band is the same as that of the main inductor L. P _1 and L P If the impedance is much smaller than that of _2, the input voltage V on the transmitting side in The main inductor L P1 _1 and L P1 The output current is equal to the sum of the voltage drops across _2, and is I1 + and I2 + It is divided into two groups, and the output current I2 + The larger current is coupled closer to the power consumption side. In other words, the second current output by current generators 202_1 and 202_2 is coupled to the main inductor L in the two transformers. P _1 and L P The voltage drop ratio of _2 is divided into two groups, and of the two groups, the maximum output current I2 + It is coupled near the power consumption side, and the reference voltage of its current generators 202_1 and 202_2 is the secondary inductor L S1 _1 and L S1 This is the sum of the voltages across the two groups of _2 (when the coupling coefficient a=1). The reference voltage of current generator 202_1 is the secondary inductor L S1 This comes from the voltage across _1. The key to this design is that the tolerance of circuit 800 for component tolerances is maintained at 5% rather than less than 1%, thereby achieving a 100-fold increase in inductance value. For example, due to the error of the current generator 202_2, the main inductor L P The actual voltage across _2 is 0.95Vin, and the current generator 202_1 uses I1 with a voltage of 0.05Vin across it. + To produce it, the accuracy requirement is still maintained at 5%. Main inductor L P _1 and L P If the inductance values of _2 are the same, the main inductor L P The voltage of _2 is V in When the current value is I0, the current generator (input voltage is Vin) is I2 + ~0.89I0, I1 +This generates ~0.09I0. In this case, circuit 800 can increase the average inductance value by 100 times, and the actual value becomes approximately 50 to 200 times, and the circuit remains stable without oscillation. The main reason is that two voltage drops occur, and the voltage drop closer to the signal end (transmitter side) is 0.1 times the original voltage (i.e., 0.1V). in Since 90% of the current is coupled by the current generator 202_1, the signal source itself only needs to bear 1% of the current. This is equivalent to increasing the inductance by 100 times.
[0019] The above circuit, which uses two inductors (or transformers), can be extended in the same way to a circuit with multiple inductors to generate multiple currents and increase the inductance value.
[0020] Refer to Figures 9A and 9B. Figure 9A shows a schematic diagram of another embodiment of the current generator 202, and Figure 9B shows a schematic diagram of the circuit of the present invention in one embodiment. In this embodiment, the current generator 202 mainly consists of an analog-to-digital converter 202A, a digital inductor current calculator 202B, and a current-to-digital-to-analog converter 202C. The digital inductor current calculator 202B is a digital circuit, and the analog-to-digital converter 202A digitizes the coupling voltage and transmits it to the digital inductor current calculator 202B to power the first inductor L S1 The current output is converted to digital information, and this information is sent to the current digital-to-analog converter 202C, and the actual current I + Generates.
[0021] Therefore, in addition to the method of replicating the main inductor current by adding the coupling voltage to the actual reference inductor, the coupling voltage is digitized using an analog-to-digital converter, the inductor current is then predicted by digital calculation, the digitized information is output to a current-to-digital-to-analog converter to generate the actual current, and it is sent back to the coupler (as shown in the schematic diagram in Figure 9B). In this method, the reference inductor is not required, but the calculation clock of the calculation circuit needs to be relatively fast so that the time delay does not become too large and affect the current suppression effect of the high-frequency signal.
[0022] As mentioned earlier, to improve power line communications, isolators can be used to separate power lines into power-consuming and power-transmitting sides, avoiding the impact of time-varying noise and impedance on the power-consuming side within the communication frequency band on communication effectiveness. These isolators require not only differential mode filters to suppress differential mode noise, but also common mode chokes to suppress common mode noise. Common mode chokes typically require a pair of inductors with larger inductance values. When the isolator is placed in a path of large AC currents (e.g., the input of a power meter), conventionally manufactured common mode chokes require a large magnetic core and a sufficient number of windings to achieve common mode noise suppression. Common mode chokes are expensive and bulky because the cross-sectional area of the copper wire needs to be sufficiently large to keep the temperature rise of the isolator within a safe range when high power currents flow through it. Common mode chokes are also frequently used to suppress electromagnetic interference (EMI) from high-current equipment to comply with safety regulations. This invention primarily uses an active current generator circuit to enhance the suppression of common-mode and differential-mode noise, as well as the EMI suppression effect, thereby reducing the cost and volume of isolators and EMI suppression circuits. Because the length of the copper wire is shortened, the energy consumption of this isolator or EMI suppression circuit is also lower than in conventional methods, resulting in reduced energy loss.
[0023] To improve power line communications, isolators are used to remove noise on the transmission line. Isolators typically consist of passive inductors and capacitors, and because they need to simultaneously remove common-mode and differential-mode noise, they usually include a common-mode choke. When an isolator is in the path of a high-power current, its inductor is usually large in volume and costly, and the copper wire wrapped around the magnetic core becomes relatively long, consuming more electrical energy. Common-mode chokes are also commonly and widely used to suppress electromagnetic interference (EMI). The technology of this invention uses an active circuit to enhance the effectiveness of the isolator and EMI suppression circuit, reducing cost and volume, and reducing energy consumption due to heat generation from the copper wire.
[0024] Furthermore, isolators typically consist of passive inductors and capacitors, and generally, isolators are actually high-frequency filters, removing common-mode noise in addition to differential-mode noise. Therefore, practical isolators usually need to be able to remove differential-mode and common-mode noise simultaneously, and Figures 10A and 10B show typical isolator circuits in the prior art. Common-mode chokes play an important role in isolators and are primarily used to suppress high-frequency common-mode noise or common-mode current. As shown in Figures 11A, 11B, and 11C, in addition to isolators, common-mode chokes are often used to suppress EMI in high-current equipment to comply with safety regulations. Circuits that purely suppress EMI usually have parallel capacitors on both sides because there is no need to consider the higher input impedance on the transmitting side. As shown in Figure 11B, due to the problem of magnetic leakage, common-mode chokes also have the effect of differential-mode filtering, so there are also EMI suppression circuits consisting only of common-mode chokes and capacitors.
[0025] Common mode chokes typically require larger magnetic cores and thicker copper wire windings to achieve higher common mode inductance values, and the temperature rise when rated power current flows must be controlled within a safe range. Because these two conditions must be met simultaneously, common mode chokes capable of handling high power currents are usually bulky and expensive.
[0026] This embodiment discloses an active common-mode or differential-mode choke and power line filter comprising at least three coils, an active suppression current generating circuit, and a capacitor. Of the at least three coils, two are used to carry power currents (the magnetic fields generated by low-frequency power currents may cancel each other out, and the magnetic field is strengthened when high-frequency common-mode noise currents flow), and the other coil is used to carry a high-frequency suppression current. The active suppression current generating circuit couples these coils to generate an active suppression current. The capacitor, acting as a power line filter, is coupled to the two coils for carrying power currents. The active suppression current generating circuit generates a suppression current in a proportion corresponding to the common-mode noise current, thereby generating a magnetic field within the magnetic cores of these coils generated by the original common-mode noise current, and suppressing the common-mode noise current from flowing through the two coils of power current.
[0027] Isolator circuits or EMI suppression circuits often incorporate several differential mode coils in addition to a common mode choke. Various mixed winding methods exist, and these differential mode coils can also be reinforced with similar active current suppression circuits to simultaneously achieve cost, volume, and power consumption reductions.
[0028] Similar to the high-current inductor circuits disclosed previously, the common-mode choke of the present invention can also increase its equivalent inductance value using an active suppression current. As shown in Figure 12, Figure 12 shows a schematic diagram of the present invention when a common-mode noise current flows through the common-mode coils CMC1 to CMC2. In this embodiment, when a common-mode noise current flows through the common-mode coils CMC1 to CMC2, a magnetic field is generated in the magnetic core. If a similar magnetic field can be generated by another active common-mode suppression current, the flow of common-mode noise current to the common-mode chokes CMC1 to CMC2 can be suppressed. In an ideal case, the common-mode noise current can be completely suppressed by the magnetic field generated by the active suppression current. In one embodiment, if the magnitude and phase of the noise currents flowing through the ports of the two circuits of the common-mode coils CMC1 to CMC2 of the common-mode choke, for example, ports B1 and B2, and ports N1 and N2, are different, the suppressed noise will be the average of the noises of the two circuits, and the remaining noise will take the form of a differential mode, which can be mitigated by other differential-mode filter circuits. In Figure 12, the voltage difference generated across the inductor by the low-frequency power current is not large, and since the current direction of the low-frequency power current is opposite in the two circuits, most of the generated magnetic fields cancel each other out, reducing the problem of magnetic saturation. High-frequency common-mode noise generates a voltage difference and current across the coil. If the magnitude of the common-mode noise current in the two wires is the same, the magnetic field generated by the active common-mode suppression current can completely replace the magnetic field where the active common-mode suppression current is zero, and the flow of common-mode noise current through the common-mode coils CMC1 to CMC2 of the common-mode choke can be greatly reduced.
[0029] Figure 13 shows a schematic diagram of circuit 40A of an active common-mode choke and power line filter in one embodiment. Figure 13 is intended to increase the common-mode inductance value of the common-mode choke and is not effective in suppressing differential-mode noise. In Figure 13, the noise current I in the two circuits... in1 / I in2The copper wire through which the current flows is a thick wire (because it needs to carry a large power current), but the active suppression current I + / I - A thin wire should be used for the coil through which the current flows.
[0030] In this embodiment, the active common mode choke and power line filter circuit 40A includes three common mode coils CMC1 to CMC3, of which two common mode coils CMC1 to CMC2 are used to carry power current, and the other common mode coil CMC3 carries active suppression current I + It is used to conduct the common mode noise current. The active common mode choke circuit 40A couples common mode coils CMC1~CMC3. The active common mode choke circuit 40A includes a coupler 201 and a common mode current generator 202_C, and common mode noise current I in1 , I in2 A suppression current I of a proportion corresponding to the current + This is used to generate and replace the magnetic field generated by the common-mode noise current within the magnetic core of the common-mode coils CMC1-CMC3. For a complete isolator or EMI suppression circuit, a capacitor (not shown) is connected in parallel between the ports of the two coils CMC1-CMC2 that carry the power current of the common-mode choke to remove differential-mode noise.
[0031] In this embodiment, the winding ratio of the common mode chokes CMC1:CMC2:CMC3 is N:N:M, where N and M are constants. Noise current I flows through the common mode coils CMC1 to CMC2. in1 , I in2 (The noise current consists of common-mode noise and differential-mode noise.) When the voltages generated by common-mode coils CMC1 and CMC2 are V1 and V2, respectively, common-mode coil CMC3 generates a coupling voltage M(V1+V2) / 2N. The common-mode current generator 202_C generates a suppression current I according to the coupling voltage (aM(V1+V2)) / N received from coupler 201 or another coupler. +The common-mode current generator 202_C generates a corresponding rate of suppression current I using the same coupler 201 or another coupler. + The common-mode current generator 202_C is coupled and output, replacing the magnetic field generated by the common-mode noise current within the magnetic core of the common-mode choke. If non-ideal mutual inductance issues between coils, such as magnetic leakage, are not considered, then the magnetic field replaced will be only the common-mode portion, and the magnetic field generated by differential-mode noise cannot be suppressed; therefore, another capacitor or differential-mode inductor is required to remove the differential-mode noise. As shown in the schematic diagram of Figure 14, in the active common-mode choke circuit 50, the common-mode current generator 202_C may be implemented by an amplifier. The amplifier has another reference inductor L at its load terminal. S2 The amplifier drives a common mode coil CMC3, and its inductance value is L1. In this embodiment, the amplifier has a first input terminal 1 and a second input terminal 2, and the first input terminal 1 and the second input terminal 2 are coupled to the input terminal and output terminal of the common mode coil CMC3, respectively. Furthermore, the amplifier has a first output terminal Q1, a second output terminal Q2, a third output terminal Q3, and a fourth output terminal Q4, and the first output terminal Q1 and the fourth output terminal Q4 are connected to a reference inductor L as load terminals. S2 It is connected in series with the first input terminal 1 and the third output terminal Q3 are connected in parallel with the coupler 201 (capacitor C in this embodiment), and the second output terminal Q2 is connected in parallel with the second input terminal 2, and a matching impedance Z exists between the first input terminal 1 and the coupler 201, and a matching impedance Z exists between the second input terminal 2 and the second output terminal Q2. The first input terminal 1 and the first output terminal Q1 are connected in parallel with the matching impedance KZ, and the second input terminal 2 and the fourth output terminal Q4 are connected in parallel with the matching impedance KZ. In this embodiment, the reference inductor L S2 It is connected in series with a large capacitor CR.
[0032] Noise current I in1 =I in2 =I CNIn other words, if the noise is pure common-mode noise, the suppression current I + The value is equal to 0, and the common mode noise current I in the N-turn common mode coils CMC1~CMC2 in1 , I in2 If the voltage across each of the terminals is V, then the voltage induced by the common mode coil CMC3, which acts as a suppression coil (number of turns M), is (M / N) × V. In the ideal case, the suppression current I + = (2N / M)I CN As a result, most of the common-mode noise current can be suppressed. As shown in Figure 14, this suppression current I + The reference inductor L is accessed via an amplifier. S2 (Reference inductor L) S2 The voltage V is applied across the ends of the amplifier by the amplifier. L1 ) can be driven, and as a result, the suppression current I is suppressed by another corresponding ratio (H times) of current that is generated. + This generates the following: If the number of turns on one side of the common mode coil CMC1 and common mode coil CMC2 is N, the inductance value is L0, and the amplifier's multiplier is K, then the reference inductor L S2 The inductance value L1 is (M 2 ×K×H / (2N 2 )) L0. The suppression current I generated in this way + is (2N / M)I CN It becomes approximately equal to (2N / M)I. CN Suppression current I equal to + If we can generate this, we can suppress most of the common-mode noise current, I in1 or I in2 It can be made to approach 0.
[0033] If the source of common-mode noise current originates from the transmitting side (e.g., radiated noise in the air), this noise cannot be removed by an isolator (because it is mixed with the communication signal on the transmitting side). At this point, the only way to mitigate its effects is to hope that this common-mode noise is not converted into differential-mode noise during the transmission process (typical communication signal transceivers have excellent common-mode noise immunity). As shown in Figures 15A and 15B, Figures 15A and 15B show schematic diagrams of symmetrical differential-mode choke circuits, respectively. If the differential-mode choke of the isolator can be made symmetrical, common-mode noise from the power consumption side and common-mode noise from distant sources on the transmitting side will become closer to common-mode when they reach B1 / N1 (transceiver port), reducing the impact on communication. Currently, commercially available isolators are all one-sided differential-mode coils as shown in Figure 10A. The main reasons for this are low manufacturing costs and the fact that the application scenarios are short distances indoors, so the effects of radiated or coupled common-mode noise are not considered. Symmetrical isolators are suitable for long-distance outdoor power lines and can prevent interference with communication signal transmission due to radiated or coupled (e.g., underground noise coupled to buried cables) noise. The difference between Figure 15A and Figure 15B is that Figure 15B has two coils with independent magnetic cores, and by adding active suppression circuits to both, the suppression of differential mode noise and common mode noise can be enhanced simultaneously. Nc, Mc, Nd, and Md shown in Figures 15A and 15B represent the number of coil turns.
[0034] As shown in Figure 16, the present invention can also be used as a differential mode choke, which shows a schematic diagram of an active differential mode choke circuit 70. Differential mode coils DMC1-DMC3 can also enhance the differential mode noise suppression effect in the same manner as described above. Symmetrical differential mode chokes DMC1-DMC2 help to further balance the common mode noise current in the two circuits, so that a smaller proportion is converted to differential mode noise and appears on the transmission side. Finally, instead of the magnetic field generated by the differential mode noise current within the magnetic core of the differential mode coils DMC1-DMC2, the differential mode suppression current generator 202_D outputs a differential mode suppression current to suppress differential mode noise. A schematic diagram of the corresponding circuit is shown in Figure 17, and its principle is the same as described above. In the ideal case, this circuit can suppress only differential mode noise and not common mode noise. The complete active isolator circuit diagram is shown in 15A. The concepts described above can also be used in circuits that suppress EMI. Since high impedance is not required on the transmission side, capacitors can be added to both sides (as shown in Figure 18). Some EMI suppression circuits focus on suppressing common-mode noise current, while differential-mode noise current can only be eliminated by the magnetic leakage effect of a common-mode choke and a capacitor. Such circuits can be completed by discarding the differential-mode inductor and using only a common-mode choke and a capacitor (as shown in Figure 19).
[0035] In actual active inductance enhancement circuits, it is often necessary to lower the Q value (Quality Factor) of the LC components to suppress oscillation, and it is often necessary to add several small resistors to the capacitor path. These resistors reduce the filtering effect of differential mode noise, but they also stabilize the entire circuit and prevent oscillation, so the circuit does not produce unexpected oscillations (resistors R1 to R3 as shown in Figure 20). Nc, Nc1, Nc2, Mc, Mc1, Mc2, Nd, Nd1, Nd2, and Md shown in Figures 18 to 20 represent the number of coil turns. [Explanation of Symbols]
[0036] 200A, 200B, 200C, 200D, 300A, 300B, 500A, 500B, 600, 700, 800, 900: Circuit V: Voltage across the main inductor 201, 201_1, 201_2: Coupler 202, 202_1, 202_2: Current generators 202A: Analog-to-Digital Converter 202B: Digital Inductor Current Calculator 202C: Current-to-digital-to-analog converter L P 1, L P 1_1, L P 1_2: Main Inductor L, L S2 :Inductor L S , L S1 , L S1 _1, L S1 _2: Secondary inductor V in : Input voltage of the isolator or filter Vc: Inductor L S The voltage generated by the change in magnetic flux is shown above. V L1 Inductor L S2 voltage I0: Current value flowing through the main inductor or main transformer coil generated by the signal source. I in : Current flowing through the main inductor generated by the signal source I + , I - : Current generated by a current generator Ic: Current value generated by the current generator L0, L2: Inductance values of the main inductor L1: Inductance value of the reference inductor of the current generator I L1 Inductor L S2 Current flowing through C, C X , C Y , C R : Capacitor Z, KZ: Impedance M, M1, M2, N, K, a: Constant ω: Angular frequency 1, 2: Input terminals Q1~Q4: Output terminals LNA: Linear Amplifier T2, T3: Transformers 204: Low-pass filter
Claims
1. A circuit for increasing the inductance of a high-current inductor, The circuit includes a main inductor, a coupler, and a current generator. A first current related to the communication signal flows through the main inductor, generating a voltage related to the communication signal, the main inductor is located on the power line, and alternating current or direct current flows through the main inductor simultaneously. The coupler senses the voltage across the main inductor or a predetermined percentage of the voltage across the main inductor and generates a coupling voltage. The current generator generates a second current based on the coupling voltage received from the coupler or another coupler, the current generator couples the second current to the main inductor by the same coupler or another coupler, the second current returns to the coupler and then to the current generator, The purpose of the current generator is to generate the second current by replicating the first current, and since the phase of the second current is close to the phase of the first current flowing through the main inductor, the first current, which is driven by the communication signal of the circuit itself, is suppressed by flowing the second current through the main inductor. circuit.
2. The circuit according to claim 1, wherein the current generator generates the second current based on the coupling voltage received from the coupler or another coupler, and the second current flows through a coil wound on the same magnetic core as the main inductor.
3. The circuit includes a first inductor, The first inductor is connected in parallel between the coupler and the main inductor, and the first inductor and the main inductor are connected in series and wound on the same magnetic core. The coil wire diameter of the first inductor is smaller than the coil wire diameter of the main inductor, and only the communication signal current flows through the coil of the first inductor. The circuit according to claim 1.
4. A circuit for increasing the inductance of a high-current inductor, The circuit includes a main inductor, a first inductor, a coupler, and a current generator. A first current related to the communication signal flows through the main inductor, generating a voltage related to the communication signal, the main inductor is located on the power line, and alternating current or direct current flows through the main inductor simultaneously. The first inductor generates another voltage based on the voltage across the main inductor or a predetermined ratio of the voltage across the main inductor. The coupler senses the voltage across the first inductor or a predetermined percentage of the voltage across the first inductor and generates a coupling voltage. The current generator receives the coupling voltage using the coupler or another coupler and generates a second current, and the current generator couples the second current using the same coupler or another coupler, thereby causing the main inductor to generate a back electromotive force. The purpose of the current generator is to generate a second current that replicates the magnetic field generated by the first current within the magnetic core of the main inductor, in order to suppress the first current driven by the communication signal of the circuit itself. circuit.
5. The first inductor is coupled to the coupler, and the first inductor and the main inductor are wound on the same magnetic core to form the first transformer. The second current flows to the first inductor instead of the main inductor, suppressing the first current flowing to the main inductor, and the first transformer is used to isolate the high voltage on the power transmission side from entering the coupler. The circuit according to claim 4.
6. The current generator comprises one or more amplifiers and a reference inductor, which are used as a current replication circuit. The current replication circuit operates with the voltage applied across the reference inductor by the amplifiers. Since the voltage across the reference inductor is proportional to the voltage across the main inductor, current flows through the reference inductor, and the current replication circuit generates and outputs a second current that is proportional to the current of the reference inductor. The circuit according to claim 1 or claim 4.
7. The current generator mainly comprises an analog-to-digital converter, a digital inductor current calculator, and a current-to-digital-to-analog converter. The digital inductor current calculator is a digital circuit, the analog-to-digital converter digitizes the coupling voltage and transmits it to the digital inductor current calculator to calculate the digitized information of the current output by the first inductor, and transmits the digitized information to the current-to-digital-to-analog converter to generate the actual second current. The circuit according to claim 1 or claim 4.
8. The circuit has a transformer formed by the first inductor and the main inductor, the current generator is a differential linear driver, and the differential linear driver has a first input terminal, a second input terminal, a first output terminal, a second output terminal, a third output terminal, and a fourth output terminal. The first input terminal and the second input terminal are coupled to the input and output terminals of the first inductor, respectively; the first output terminal and the fourth output terminal are connected in series to the second inductor as load terminals; the first input terminal and the third output terminal are coupled in parallel to the coupler; the second output terminal is coupled in parallel to the second input terminal; a first matching resistor exists between the first input terminal and the coupler; a second matching resistor exists between the second input terminal and the second output terminal; the first input terminal and the first output terminal are connected in parallel to the third matching impedance; and the second input terminal and the fourth output terminal are connected in parallel to the fourth matching impedance. The circuit according to claim 4.
9. The impedance value of the matching impedance Z of the differential linear driver is ωL ０ or ωL １ Larger than, where ω is the angular frequency of the communication frequency band, L ０ L is the inductance value of the main inductor. １ The circuit according to claim 8, wherein is the inductance value of the second inductor.
10. The circuit includes a linear amplifier, which is positioned between the power transmission side and the power consumption side, and is coupled to a second transformer and a third transformer on the power transmission side and the power consumption side, respectively. The input terminals of the linear amplifier are coupled to both ends of the secondary coil of the second transformer, and a first input impedance is coupled to both the input terminals of the linear amplifier and both ends of the secondary coil of the second transformer, respectively. The output terminals of the linear amplifier are coupled to both ends of the primary coil of the third transformer, and a second output impedance is connected in parallel between the output terminals and the input terminals of the linear amplifier, respectively. The circuit according to claim 5.
11. The circuit has a second inductor, the second inductor and another main inductor form a second transformer, the first transformer has a corresponding first coupler and a first current generator, the second transformer has a corresponding second coupler and a second current generator, the second coupler has two forward output terminals for the second current, one of which is coupled to the forward output terminal of the second current of the first coupler, and the other is coupled to the input terminal of the second inductor. If a filter capacitor is connected in parallel to the power consumption side of the circuit, and the impedance of the filter capacitor in the communication frequency band is much smaller than the impedance of the main inductor, then the input voltage on the power transmission side corresponds to the sum of the voltage drops across these main inductors, and the second current output by the current generator is divided into two groups according to the voltage drop ratio of the main inductors in the first and second transformers, with the largest of the two groups, the second current, being coupled near the power consumption side. The circuit according to claim 5.
12. The circuit according to claim 11, wherein, when the coupling coefficient of the first coupler and the second coupler is 1, the reference voltages of the first current generator and the second current generator are the sum of the voltages across the first inductor and the second inductor, respectively, and the reference voltage of the first current generator is derived from the voltage across the first inductor.
13. The circuit according to claim 4, wherein when the circuit is in the low-frequency AC current frequency band, the current generator does not generate the second current flowing through the coil of the first inductor.