Magnetic modulation oscillation circuit and driving method thereof

Abstract

The embodiment of the present application provides a magnetic modulation oscillation circuit and a driving method thereof. The magnetic modulation oscillation circuit includes a magnetic ring; at least one coil wound on the magnetic ring; a sampling circuit connected to at least one coil and outputting a sampling signal; a differentiator connected to the sampling circuit and outputting a differential signal; a comparator connected to the differentiator and outputting a comparison result signal based on a comparison of the differential signal with a preset threshold; a pulse shielding circuit connected to the comparator and outputting a drive control signal and keeping the drive control signal unchanged within a predetermined time after the comparison result signal changes; a drive circuit connected to the pulse shielding circuit to receive the drive control signal and drive at least one coil to generate an oscillation signal. The technical solution of the embodiment of the present application can accurately control the drive circuit of the magnetic modulation oscillation circuit, so that the moment of the polarity change point of the drive signal is basically consistent with the moment of the critical point of the magnetic ring entering the magnetic saturation state from the non-magnetic saturation state.

Description

Technical Field

[0001] The invention relates to the field of current protection, and in particular to a magnetic modulation oscillation circuit and a driving method thereof. Background Art

[0002] In an AC or DC power supply system, magnetic modulation technology can be used to detect the current in the power supply line. For example, the residual current in the AC power supply line can be detected. When the residual current is detected to be greater than a set threshold, the connection between the power supply line and the load is disconnected, thereby protecting the load and personnel.

[0003] The polarity of the driving signal can be changed alternately by changing the polarity of the power source (e.g., voltage source, current source), and the coil receives the driving signal so that the working state of the magnetic ring wound by it also changes alternately. However, in the process of dynamic change of the working state, it is difficult to accurately control the change of the polarity of the driving signal. Summary of the invention

[0004] The technical problem solved by the present invention is that it is difficult to accurately control the polarity change of the driving signal.

[0005] To solve the above technical problems, an embodiment of the present invention provides a magnetic modulation oscillation circuit, comprising: a magnetic ring, which is suitable for allowing at least one conductor through which a current to be measured can pass; at least one coil, which is wound on the magnetic ring; a sampling circuit, which is connected to one end of each coil in the at least one coil and is suitable for outputting a sampling signal; a differentiator, whose input end is connected to the sampling circuit to receive the sampling signal and is suitable for outputting a differential signal; a comparator, whose input end is connected to the output end of the differentiator to receive the differential signal and is suitable for outputting a comparison result signal based on a comparison between the differential signal and a preset threshold; a pulse shielding circuit, whose input end is connected to the output end of the comparator to receive the comparison result signal, is suitable for outputting a drive control signal and keeping the drive control signal unchanged within a predetermined time after the comparison result signal changes; a drive circuit, whose input end is connected to the output end of the pulse shielding circuit to receive the drive control signal and whose output end is connected to the other end of each coil in the at least one coil to drive it to generate an oscillation signal.

[0006] Optionally, the output terminal of the pulse masking circuit is connected to the input terminal of the comparator to control a preset threshold.

[0007] Optionally, the predetermined time length is greater than or equal to 10 microseconds and less than a half period of the oscillation signal.

[0008] Optionally, at least one coil includes a coil, the sampling circuit includes a sampling resistor, one end of the sampling resistor is connected to one end of a coil and the input end of the differentiator, and the other end is connected to the ground, and the output end of the drive circuit is connected to the other end of the coil.

[0009] Optionally, the pulse masking circuit includes a pulse generator and a latch, the input end of the pulse generator is connected to the output end of the comparator to receive a comparison result signal, the output end is connected to the clock end of the latch to output a clock signal, the data end of the latch is connected to the output end of the comparator to receive a comparison result signal, the clock end receives the clock signal, and the output end outputs a drive control signal based on the comparison result signal and the clock signal.

[0010] Optionally, the pulse masking circuit further includes a buffer, which is suitable for allowing the comparison result signal to first reach the latch and then reach the pulse generator, and the input end of the pulse generator is connected to the output end of the comparator through the buffer.

[0011] Optionally, at least one coil includes a first coil and a second coil, wherein: the sampling circuit includes a sampling resistor, a first end and a second end of the sampling resistor are respectively connected to one end of the first coil and the second coil and are respectively suitable for outputting a first sampling signal and a second sampling signal; a first input end and a second input end of the input end of the differentiator are respectively connected to the first end and the second end of the sampling resistor to receive the first sampling signal and the second sampling signal and are respectively suitable for outputting a first differential signal and a second differential signal; a first input end and a second input end of the input end of the comparator are respectively connected to a first output end and a second output end of the output end of the differentiator to receive the first differential signal and the second differential signal and are respectively suitable for comparing with a first preset threshold value and a second preset threshold value to output a first comparison result signal and a second comparison result signal; The first input terminal and the second input terminal of the input terminal of the pulse shielding circuit are respectively connected to the first output terminal and the second output terminal of the output terminal of the comparator to receive the first comparison result signal and the second comparison result signal and are respectively suitable for outputting the first drive control signal and the second drive control signal, and keeping the first drive control signal and the second drive control signal unchanged within the first predetermined time length and the second predetermined time length after the first comparison result signal and the second comparison result signal are changed; the first input terminal and the second input terminal of the input terminal of the driving circuit are respectively connected to the first output terminal and the second output terminal of the output terminal of the pulse shielding circuit to receive the first drive control signal and the second drive control signal, and the first output terminal and the second output terminal of the output terminal of the driving circuit are respectively connected to the other end of the first coil and the second coil.

[0012] Optionally, the first output terminal and the second output terminal of the pulse masking circuit are respectively connected to the first input terminal and the second input terminal of the comparator to respectively control the first preset threshold and the second preset threshold.

[0013] Optionally, the pulse masking circuit includes a first latch, a second latch, a first pulse generator and a second pulse generator, wherein: the input end of the first pulse generator is connected to the first output end of the comparator to receive a first comparison result signal, and the output end is connected to the clock end of the first latch to output a first clock signal; the data end of the first latch is connected to the first output end of the comparator to receive the first comparison result signal, the clock end receives the first clock signal, and the output end outputs a first drive control signal based on the first comparison result signal and the first clock signal; the input end of the second pulse generator is connected to the second output end of the comparator to receive the second comparison result signal, and the output end is connected to the clock end of the second latch to output a second clock signal; the data end of the second latch is connected to the second output end of the comparator to receive the second comparison result signal, the clock end receives the second clock signal, and the output end outputs a second drive control signal based on the second comparison result signal and the second clock signal.

[0014] Optionally, the first pulse generator and the second pulse generator further include a first buffer and a second buffer, respectively, wherein: the first buffer is suitable for allowing the first comparison result signal to first reach the first latch and then reach the first pulse generator, and the input end of the first pulse generator is connected to the first output end of the comparator through the first buffer; the second buffer is suitable for allowing the second comparison result signal to first reach the second latch and then reach the second pulse generator, and the input end of the second pulse generator is connected to the second output end of the comparator through the second buffer.

[0015] An embodiment of the present invention also provides a method for driving a magnetic modulation oscillation circuit, comprising: collecting an oscillation signal at at least one coil and outputting a sampling signal; processing the sampling signal and outputting a differential signal; outputting a comparison result signal based on a comparison between the differential signal and a preset threshold; outputting a drive control signal based on the comparison result signal and keeping the drive control signal unchanged within a predetermined time after the comparison result signal changes, wherein the drive control signal controls the preset threshold; and outputting a drive signal based on the drive control signal to enable at least one coil to generate an oscillation signal.

[0016] Optionally, the predetermined time length is greater than or equal to 10 microseconds and less than a half period of the oscillation signal.

[0017] Optionally, the method includes: outputting a clock signal based on the comparison result signal, and outputting a driving control signal based on the comparison result signal and the clock signal.

[0018] Compared with the prior art, the technical solution of the embodiment of the present invention has beneficial effects. For example, the driving circuit of the magnetic modulation oscillation circuit is accurately controlled so that the moment of the driving signal polarity change point can be basically consistent with the critical point of the magnetic ring entering the magnetic saturation state from the non-magnetic saturation state. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a first structural schematic diagram of a magnetic modulation oscillation circuit according to an embodiment of the present invention;

[0020] Figure 2 is a second structural schematic diagram of the magnetic modulation oscillation circuit according to an embodiment of the present invention;

[0021] Figure 3 It is a curve diagram of magnetic induction intensity and magnetic field intensity on a magnetic ring in the prior art;

[0022] Figure 4 is a schematic structural diagram of a pulse shielding circuit according to an embodiment of the present invention;

[0023] Figure 5 is a waveform diagram of relevant signals in the magnetic modulation oscillation circuit according to an embodiment of the present invention;

[0024] Figure 6 is a third structural schematic diagram of the magnetic modulation oscillation circuit according to an embodiment of the present invention;

[0025] Figure 7 It is a flow chart of a method for driving a magnetic modulation oscillation circuit according to an embodiment of the present invention. DETAILED DESCRIPTION

[0026] The existing magnetic modulation technology collects the current on the coil, and when it is equal to or exceeds the threshold, the polarity of the driving signal is changed to magnetize the magnetic ring in the opposite direction. However, when the current is collected and the current value is compared with the threshold, the driving signal in the coil and the magnetic field induced in the magnetic ring are still changing, so that the moment of polarity change of the driving signal determined based on the threshold comparison is inconsistent with the moment when the magnetic ring enters the magnetic saturation state from the non-magnetic saturation state.

[0027] In an embodiment of the present invention, the changing law of the current in the coil wound on the magnetic ring is taken into consideration, that is, under the drive of the driving circuit, the magnetic ring runs periodically along the hysteresis loop. When the magnetic ring gradually runs towards a magnetic saturation state, the current in the coil gradually increases, and the sampling signal gradually increases. When the magnetic ring enters a magnetic saturation state from a non-magnetic saturation state, the current in the coil increases rapidly.

[0028] It is also considered that directly comparing the sampling signal (for example, the sampling current, the sampling voltage) with the threshold value based on the physical phenomenon of the current change in the coil cannot accurately and timely reflect the state change of the magnetic ring from the non-magnetic saturation state to the magnetic saturation state; another physical phenomenon in the process of the magnetic ring entering the magnetic saturation state from the non-magnetic saturation state can be directly linked (that is, the rate of change of the current in the coil increases rapidly), so that the polarity change of the drive signal can be accurately and timely controlled based on the rate of change of the current in the coil.

[0029] Specifically, the sampling signal is received and processed by a differentiator and a differential signal is output. The differential signal reflects, for example, the rate of change of the current in the coil, and is directly based on the comparison of the differential signal with a preset threshold without introducing other additional inputs or comparisons, so that the output drive control signal and the drive signal can be obtained directly and timely, so that the polarity change of the drive signal can be basically consistent with the moment when the magnetic ring enters the magnetic saturation state from the non-magnetic saturation state.

[0030] For example, the comparator can obtain a comparison result signal based on the comparison between the differential signal and the preset threshold, the pulse shielding circuit can output a drive control signal based on the comparison result signal, and the drive circuit can output a drive signal based on the drive control signal, so that the moment of the polarity change point of the drive signal can be basically consistent with the moment when the magnetic ring enters the magnetic saturation state from the non-magnetic saturation state in real time, thereby accurately controlling the polarity change of the drive signal.

[0031] In an embodiment of the present invention, when the comparator outputs a comparison result signal based on the comparison of the differential signal with a preset threshold, the comparison result signal may contain short pulses (glitches); a pulse shielding circuit can be connected to the output end of the comparator, whose input end receives the comparison result signal output by the comparator and keeps the output drive control signal unchanged within a predetermined time after the comparison result signal changes, so that the drive control signal can be kept unchanged during the period when the output end of the comparator outputs the glitches.

[0032] In an embodiment of the present invention, when the comparator outputs a comparison result signal based on the comparison of the differential signal with the preset threshold, since the comparison result signal may contain short pulses (glitches), if the output of the comparator is connected to the input of the comparator through a feedback loop, then controlling the preset threshold of the comparator based on the rising and falling edges of these glitches will cause the preset threshold to flip frequently and unnecessarily; a pulse shielding circuit can be connected to the output of the comparator, whose input receives the comparison result signal output by the comparator, whose output is connected to the input of the comparator through a feedback loop, and whose output drive control signal remains unchanged within a predetermined period of time after the comparison result signal changes, so that the polarity of the preset threshold can still be kept stable during the period when the output of the comparator outputs glitches.

[0033] When describing the embodiments of the present invention in conjunction with specific drawings, the elements represented by the same figure marks in the drawings, such as magnetic rings, conductors, coils, circuits and resistors, are the same elements and have the same functions and connection relationships.

[0034] In an embodiment of the present invention, the connection includes an electrical connection for transmitting electrical parameters between different elements, and a signal connection for transmitting electrical signals between different elements.

[0035] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and understandable, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0036] Figure 1 The overall structure of the magnetic modulation oscillation circuit in the embodiment of the present invention is shown. Figure 2 The magnetic modulation oscillator circuit 100 , 200 includes a magnetic ring 110 , at least one coil 120 , a sampling circuit 130 , a differentiator 140 , a comparator 150 , a pulse masking circuit 160 and a driving circuit 170 .

[0037] The magnetic ring 110 is a closed-shaped magnetic conductor, through which at least one conductor 180 through which a current to be measured can pass passes. The current to be measured can be a direct current or an alternating current.

[0038] The conductor passing through the magnetic ring 110 can be one, such as Figure 1 As shown in the conductor 180 , the current protection device 100 can detect the current change on the conductor 180 .

[0039] There may be more than one conductor passing through the magnetic ring 110, for example, two conductors in a DC circuit (a power line and a ground line), two conductors in an AC circuit (two phase lines), three conductors in an AC circuit (three phase lines), and four conductors in an AC circuit (three phase lines and a neutral line). In an AC circuit, the vector sum of the currents passing through each conductor is a residual current, and the current protection device 100 can detect the residual current.

[0040] At least one coil is wound around the magnetic ring 110 ( Figure 1 and 2 A coil 120 is shown in the figure, which receives a driving signal so that the magnetic ring 110 wound by it induces a periodically changing magnetic field strength along the hysteresis loop, thereby generating an oscillating signal on at least one coil.

[0041] like Figure 3 As shown, the magnetic induction intensity B changes periodically with the magnetic field intensity H generated by the driving signal, and the closed curve formed is a hysteresis loop. When the magnetic field intensity H is positive, the magnetic induction intensity B has a positive magnetic saturation critical point a, and when it is negative, the magnetic induction intensity B has a negative magnetic saturation critical point b; wherein, the positive magnetic saturation critical point a is the point where the magnetic ring enters the positive magnetic saturation state from the non-magnetic saturation state, and the negative magnetic saturation critical point b is the point where the magnetic ring enters the negative magnetic saturation state from the non-magnetic saturation state.

[0042] Specifically, when the magnetic field strength H is not applied and the magnetic induction strength B in the magnetic ring 110 is zero, the magnetic field strength H is gradually increased from the origin o in the positive direction. Accordingly, the magnetic induction strength B increases along Figure 2 The oca curve in the figure also gradually increases until it reaches the positive magnetic saturation critical point a. At this time, if the magnetic field strength H is increased further, the magnetic induction intensity B will remain basically unchanged. When it just reaches the positive magnetic saturation critical point a, the value of the magnetic field strength H is represented by +Hs, and the magnetic induction intensity B is represented by +Bs.

[0043] At this time, if the magnetic field strength H is reduced in the reverse direction, the magnetization curve does not return along the original aco curve from point a; when the magnetic field strength H is reduced to zero, the magnetic induction intensity is +Br; continue to apply the reverse magnetic field strength H, when it reaches -Hc, the magnetic induction intensity B is zero; then apply the reverse magnetic field strength H, when it reaches -Hs, the magnetic induction intensity B is -Bs, that is, it reaches the reverse magnetic saturation critical point b.

[0044] At this time, if the magnetic field strength H is increased in the positive direction, when the magnetic field strength H increases to zero, the magnetic induction intensity is -Br; continue to apply the positive magnetic field strength H, when it reaches +Hc, the magnetic induction intensity B is zero; then apply the positive magnetic field strength H, when it reaches +Hs, the magnetic induction intensity B is +Bs, which means it returns to the positive magnetic saturation critical point a.

[0045] The sampling circuit 130 is connected to one end of each coil of the at least one coil, samples the electrical signal of the coil (ie, the oscillation signal generated on the coil) and outputs a sampling signal (eg, a sampling current, a sampling voltage).

[0046] In a specific implementation, the sampling circuit 130 is a sampling resistor RS connected in series with at least one coil, a first end of which is connected to one end of the at least one coil, and a second end is grounded; the sampling resistor RS samples the current flowing through the at least one coil and converts the current into a sampling voltage.

[0047] An input end of the differentiator 140 is connected to the sampling circuit 130 to receive a sampling signal, and outputs a differential signal by detecting a change rate of the sampling signal.

[0048] In an embodiment of the present invention, a specific physical phenomenon in the process of the magnetic ring entering a magnetic saturation state from a non-magnetic saturation state (i.e., the rate of change of the current in the coil increases rapidly) is associated, so that the polarity change of the drive signal can be accurately controlled based on the rate of change of the current in at least one coil.

[0049] The specific parameters of the differentiator 140 can be set so that the moment when the polarity of the drive control signal and the drive signal directly determined based on the comparison of the differential signal output by the differentiator 140 changes is substantially consistent with the moment when the magnetic ring 110 enters the magnetic saturation state from the non-magnetic saturation state.

[0050] In some embodiments, Figure 2As shown in the figure, the differentiator 140 includes an operational amplifier 141, a capacitor C0 and a feedback resistor R0, the first end of the capacitor C0 is connected to the sampling circuit 130, the positive input end of the operational amplifier 141 is grounded, the inverting input end is connected to the second end of the capacitor C0, and the output end is connected to the input end of the comparator 150, and the feedback resistor R0 is connected between the output end and the inverting input end of the operational amplifier 141; wherein, the specific parameter settings of the differentiator 140 include that the value range of the feedback resistor R0 is between 200KΩ (kilo-ohm) and 250KΩ, the value range of the capacitor C0 is between 50pF (picofarad) and 150pF, and optionally, the value of the capacitor is 100pF.

[0051] An input terminal of the comparator 150 may be connected to an output terminal of the differentiator 140 to receive a differential signal, and an input terminal of the comparator 150 is connected to the pulse masking circuit 160 to output a comparison result signal.

[0052] The input end of the pulse masking circuit 160 is connected to the output end of the comparator 150 to receive the comparison result signal; the pulse masking circuit 160 detects the rising edge and the falling edge of the comparison result signal, and outputs the driving control signal with high level and low level accordingly.

[0053] The input terminal of the comparator 150 may also be connected to a feedback loop. For example, the input terminal of the comparator 150 and the output terminal of the pulse masking circuit 160 are connected to form a feedback loop.

[0054] The comparator 150 may have a preset threshold. The polarity of the preset threshold may be controlled by the polarity of the drive control signal output by the pulse masking circuit 160. For example, the polarity of the preset threshold may be flipped by changing the polarity of the drive control signal, and may be expressed as a positive preset threshold and a negative preset threshold. The range between the positive and negative preset thresholds is the threshold window of the comparator 150. The size of the preset threshold may be set by the parameters of the feedback loop, for example, by the power supply voltage, the resistance value, etc. in the feedback loop.

[0055] The comparator 150 can output a comparison result signal based on the comparison between the differential signal and the preset threshold. Specifically, the signal output by the pulse masking circuit 160 reaches the input end of the comparator 150 through the feedback loop, and the signal (i.e., the signal of the preset threshold) is calculated with the differential signal output by the differentiator 140, and the value obtained by the calculation is compared with the reference value of the reference end of the comparator 150 to output the comparison result signal.

[0056] In some embodiments, Figure 2As shown in the figure, the comparator 150 is a hysteresis comparator composed of a positive feedback structure, including a comparator 151, resistors R1 and R2, the resistor R1 is connected between the output end of the differentiator 130 and the input end of the comparator 151, the reference end of the comparator 151 is grounded, and the resistor R2 is connected between the input end of the comparator 151 and the output end of the pulse masking circuit 160 to provide feedback to the input end of the comparator 151.

[0057] For example, the output voltage of the differentiator 130 is a negative voltage -V1, and the voltage output by the pulse masking circuit 160 is a positive voltage VDD. When the value of V1 is equal to the value of VDD*R1 / R2, the level of the input terminal of the comparator 151 is zero, which is equal to the zero level of the reference terminal, so that the output voltage of the comparator 151 is flipped; at this time, the threshold voltage relative to the output voltage of the differentiator 130 (that is, the negative voltage -V1) is a negative threshold voltage (that is, -VDD*R1 / R2, VDD represents the positive power supply voltage), and its polarity can be controlled by the polarity of the output voltage of the pulse masking circuit 160, and its size is set by the parameters of the feedback loop (that is, the values ​​of R1, R2 and VDD).

[0058] For another example, the output voltage of the differentiator 130 is a positive voltage V1, and the voltage output by the pulse masking circuit 160 is a negative voltage -VDD. When the value of V1 is equal to the value of V2*R1 / R2, the level of the input terminal of the comparator 151 is zero, which is equal to the zero level of the reference terminal, so that the output voltage of the comparator 151 is flipped; at this time, the threshold voltage relative to the output voltage of the differentiator 130 (i.e., the positive voltage V1) is a positive threshold voltage (i.e., VDD*R1 / R2, -VDD represents a negative power supply voltage), and its polarity can be controlled by the polarity of the output voltage of the pulse masking circuit 160, and its size is set by the parameters of the feedback loop (i.e., the values ​​of R1, R2 and -VDD).

[0059] Within a predetermined time period after the comparison result signal changes or the polarity is reversed, the pulse masking circuit 160 can keep the driving control signal unchanged.

[0060] When the predetermined time period is reached, a driving control signal may be output according to the comparison result signal.

[0061] At this time, if the value of the differential signal is less than the preset threshold, the polarity of the comparison result signal remains unchanged, and the polarity of the drive control signal, the polarity of the preset threshold, and the polarity of the drive signal output by the drive circuit 170 also remain unchanged.

[0062] At this time, if the value of the differential signal is equal to or exceeds the preset threshold, the polarity of the comparison result signal is reversed, and the polarity of the drive control signal, the polarity of the preset threshold, and the polarity of the drive signal output by the drive circuit 170 are also reversed; the reversed drive signal is provided to the coil to generate a reverse magnetic field (which is opposite to the magnetic field generated previously) in the magnetic ring 110, the sampling circuit 130 detects the reverse oscillation signal and outputs a reverse sampling signal (which is opposite to the previous sampling signal), the differentiator 140 receives the reverse sampling signal and outputs a reverse differential signal (which is opposite to the previous differential signal), and the comparator 150 outputs a comparison result signal based on the comparison of the reverse differential signal with the reverse preset threshold (which is opposite to the previous preset threshold).

[0063] If the output of the comparator 150 is connected to its input to provide feedback, since the comparison result signal output by the comparator 150 may contain glitches, controlling the preset threshold of the comparator based on the rising and falling edges of these glitches will cause the preset threshold to flip frequently and unnecessarily. In an embodiment of the present invention, the output of the pulse shielding circuit 160 is connected to the input of the comparator 150 to control the preset threshold, and the drive control signal is kept unchanged within a predetermined time after the comparison result signal changes, so that the pulse shielding circuit 160 can shield the comparison result signal output by the comparator 150 within the predetermined time, thereby keeping the drive control signal unchanged and keeping the preset threshold of the comparator 150 stable.

[0064] In one embodiment, the predetermined time period is greater than or equal to 10 microseconds and less than a half period of the oscillation signal.

[0065] like Figure 4 Schematically, the pulse masking circuit 160 includes a pulse generator 162 and a latch 163 .

[0066] The input end of the pulse generator 162 is connected to the output end of the comparator 150 to receive the comparison result signal (indicated as "A"), and detects the rising edge and falling edge of the comparison result signal. When the rising edge or falling edge of the comparison result signal arrives, the pulse generator 162 generates a high-level pulse signal of a predetermined width as a clock signal.

[0067] The output end of the pulse generator 162 outputs a clock signal; the data end D of the latch 163 is connected to the output end of the comparator 150 to receive the comparison result signal, the clock end Clk is connected to the output end of the pulse generator 162 to receive the clock signal, and the output end Q outputs the drive control signal Y based on the comparison result signal and the clock signal.

[0068] When the clock signal is at a high level, latch 163 latches the current drive control signal Y. At this time, the drive control signal Y output by its output terminal Q does not follow the input signal (i.e., the comparison result signal) received by its data terminal D. That is, regardless of whether the polarity or size of the input signal received by the data terminal D changes, the polarity and size of the drive control signal Y output by the output terminal Q of latch 163 remain unchanged.

[0069] When the clock signal becomes a low level, the drive control signal Y output by the output terminal Q of the latch 163 changes along with the input signal received by its data terminal D, that is, the polarity and size of the drive control signal Y output by the output terminal Q of the latch 163 change along with the polarity or size of the input signal received by the data terminal D.

[0070] Through this setting, the pulse masking circuit 160 can mask the comparison result signal output by the comparator 150 within a predetermined time period, thereby keeping the drive control signal outputted by the comparator 150 unchanged and also keeping the preset threshold of the comparator 150 stable.

[0071] In latch 163, the input signal received from the data terminal D may change, and the input signal needs time to change from one of the high level and the low level to the other of the high level and the low level; when the clock terminal Clk receives the clock signal, if the signal received from the data terminal D has not changed, the latch 163 will latch the signal before the change instead of the expected signal after the change according to the clock signal.

[0072] In order to solve this problem, the pulse masking circuit 160 may include a buffer 161, and the input end of the pulse generator 162 is connected to the output end of the comparator 150 through the buffer 161. The buffer 161 can make the time when the comparison result signal arrives at the D end of the latch 163 earlier than the time when it arrives at the input end of the pulse generator 162, and the time may be in the range of 1 to 3 nanoseconds (ns), for example, 1ns, 2ns.

[0073] An input terminal of the driving circuit 170 is connected to an output terminal of the pulse masking circuit 160 to receive a driving control signal. The driving circuit 170 is connected to a voltage source or a current source, and generates a driving signal based on the driving control signal.

[0074] The output end of the driving circuit 170 is connected to the other end of each coil in the at least one coil to form an oscillation loop, thereby providing a driving signal to the at least one coil, so that a periodically changing magnetic field strength is induced on the magnetic ring 110 wound by the at least one coil, and then an oscillation signal is generated on the at least one coil; the oscillation signal can be called a magnetic modulation oscillation signal or a basic oscillation signal, which is an unmodulated oscillation signal at this time, and the conductor 180 of the current to be measured passes through the magnetic ring 110, which can change the characteristics of the basic oscillation signal, that is, the signal of the current to be measured is modulated on the basic oscillation signal to form a modulated wave (which can be called a modulated oscillation signal).

[0075] In some embodiments, Figure 2 As shown in the figure, the driving circuit 170 has a push-pull output structure, including a buffer 171, a PMOS tube M1 and an NMOS tube M2, the input end of the buffer 171 is connected to the output end of the pulse shielding circuit 160, the output end is connected to the gates of M1 and M2, the sources of M1 and M2 are respectively connected to one and the other of the positive power supply voltage (VDD) and the negative power supply voltage (-VDD), and the drains of M1 and M2 are connected to the other end of each coil in at least one coil to drive it to generate an oscillation signal; through the push-pull output structure, the output voltage of the driving circuit 170 can be made as close to the positive and negative power supply voltages as possible, thereby greatly improving the driving efficiency of the driving circuit 170.

[0076] Figure 5 The waveform diagram of the relevant signal in the embodiment of the present invention is illustrated.

[0077] The driving signal is generated by the driving circuit, which may have a rectangular waveform formed by positive and negative levels, and the period of the rectangular waveform is T (T2 in the figure represents half a period T / 2). The positive and negative levels drive the coil alternately, so that the magnetic ring wound by it induces a periodically changing magnetic field intensity along the hysteresis loop, thereby generating an oscillating signal on at least one coil.

[0078] The sampling signal is output by the sampling circuit. In some embodiments, the sampling signal is a sampling current; when the drive signal remains at a positive level or a negative level, the sampling current gradually increases, and when the magnetic ring enters a magnetic saturation state from a non-magnetic saturation state (corresponding to the moment when the polarity of the drive signal is reversed in the figure, such as the moment when the positive level changes to the negative level or the moment when the negative level changes to the positive level), the current in the coil wound on the magnetic ring and the sampling circuit increases rapidly.

[0079] The differential signal is output by the differentiator, which is the rate of change of the sampling signal; compared with the sampling signal itself, the differential signal based on the sampling signal can more accurately reflect the critical point where the magnetic ring enters the magnetic saturation state from the non-magnetic saturation state, thereby being able to more timely control the polarity change of the drive signal at the critical point.

[0080] The comparison result signal A is output by the comparator, which is generated based on the comparison between the differential signal and the preset threshold. When the value of the differential signal is equal to or exceeds the preset threshold, the polarity of the comparison result signal A is reversed, and accordingly, the polarity of the drive control signal output by the pulse masking circuit and the drive signal output by the drive circuit are also reversed. The preset threshold includes a positive preset threshold (+VTH) and a negative preset threshold (-VTH), and the range between the positive preset threshold and the negative preset threshold is the threshold window.

[0081] When the polarity of the driving signal is reversed, the differential signal is compared with the preset threshold and a short pulse (glitch, such as the short pulses shown at a and b) is generated. T1 can be used to represent the time from the first appearance of the glitch to the time when the comparison result signal A remains stable.

[0082] The clock signal LAT is outputted by the pulse generator of the pulse masking circuit.

[0083] The drive control signal Y is output by the latch of the pulse masking circuit.

[0084] When the clock signal LAT is at a high level, the latch latches the current drive control signal Y, and at this time, it does not change with the comparison result signal A, that is, regardless of whether the polarity or magnitude of the comparison result signal A changes, the polarity and magnitude of the drive control signal Y output by the latch remain unchanged. For example, within the predetermined time length T3, the clock signal LAT is at a high level, then the comparison result signal is shielded (for example, the glitches at a and b are shielded) and the drive control signal Y is kept unchanged, so that the preset threshold remains stable.

[0085] When the clock signal LAT changes to a low level, the drive control signal Y changes with the comparison result signal A, that is, the polarity and magnitude of the drive control signal Y output by the latch change with the change of the polarity or magnitude of the comparison result signal A. For example, during the time period T2-T3, the clock signal LAT is at a low level, and the polarity and magnitude of the drive control signal Y change with the change of the polarity or magnitude of the comparison result signal A.

[0086] Specifically, when the rising edge (at a) of the comparison result signal A arrives, the drive control signal Y output by the latch is at a high level. At the same time, the rising edge makes the clock signal LAT output by the pulse generator at a high level, which is maintained for a predetermined time length T3 and makes the drive control signal Y not change with the comparison result signal A; in the time T2-T3 thereafter, the drive control signal Y follows the comparison result signal A (shown as a high level in the figure). When the falling edge (at b) of the comparison result signal A arrives, the drive control signal Y output by the latch is at a low level. At the same time, the falling edge makes the clock signal LAT output by the pulse generator at a high level, which is maintained for a predetermined time length T3 and makes the drive control signal Y not change with the comparison result signal A; in the time T2-T3 thereafter, the drive control signal Y follows the comparison result signal A (shown as a low level in the figure). In this way, the expected drive control signal Y can be output periodically.

[0087] like Figure 5 In other words, the predetermined time duration T3 is greater than T1 and less than T2; in one embodiment, T3 is greater than or equal to 10 microseconds and less than a half period T / 2 of the oscillation signal.

[0088] Figure 6 Another structure of the magnetic modulation oscillation circuit in the embodiment of the present invention is illustrated.

[0089] The magnetic modulation oscillation circuit 300 includes a magnetic ring 210 , a first coil 221 and a second coil 222 wound thereon, a sampling circuit 230 , a differentiator 240 , a comparator 250 , a pulse shielding circuit 260 and a driving circuit 270 .

[0090] The sampling circuit 230 is connected to one end of the first coil 221 and the second coil 222, samples the oscillation signals of the first coil 221 and the second coil 222 respectively, and outputs a first sampling signal and a second sampling signal, wherein the first sampling signal and the second sampling signal can be a sampling current or a sampling voltage.

[0091] In a specific implementation, the sampling circuit 230 includes a sampling resistor R1, whose first end and second end are respectively connected to one end of the first coil 221 and the second coil 222, and the sampling resistor R1 outputs a first sampling signal (ie, a first sampling voltage) and a second sampling signal (ie, a second sampling voltage).

[0092] The differentiator 240 has a differential structure, and the first input terminal and the second input terminal of the differentiator 240 are respectively connected to the first output terminal and the second output terminal of the sampling circuit 230 (for example, the first terminal and the second terminal of the sampling resistor R1) to receive the first sampling signal and the second sampling signal, and output the first differential signal and the second differential signal respectively. The first differential signal and the second differential signal are inversely proportional to each other. The differentiator 240 may also include an input terminal for a common mode voltage (VCM).

[0093] Specifically, the differentiator 240 may include capacitors C1, C2 and resistors R2 and R3. The first end of the capacitor C1 is connected to the first end of the sampling circuit 230, and the second end is connected to the positive input end of the operational amplifier 241; the first end of the resistor R2 is connected to the positive input end of the operational amplifier 241, and the second end is connected to the first output end of the operational amplifier 241; the first end of the capacitor C2 is connected to the second end of the sampling circuit 230, and the second end is connected to the reverse input end of the operational amplifier 241; the first end of the resistor R3 is connected to the reverse input end of the operational amplifier 241, and the second end is connected to the second output end of the operational amplifier 241.

[0094] The comparator 250 has a differential structure, and the first input terminal and the second input terminal of the comparator 250 are respectively connected to the first output terminal and the second output terminal of the output terminal of the differentiator 250 to receive the first differential signal and the second differential signal respectively. The first differential signal and the second differential signal can be compared with the first preset threshold and the second preset threshold respectively to output the first comparison result signal and the second comparison result signal. The first comparison result signal and the second comparison result signal are inverted. The comparator 250 also includes a first reference terminal VRL corresponding to the first input terminal and a second reference terminal VRH corresponding to the second input terminal.

[0095] The first input terminal and the second input terminal of the pulse masking circuit 260 are respectively connected to the first output terminal and the second output terminal of the comparator 250 to receive the first comparison result signal and the second comparison result signal. The pulse masking circuit 260 can output the first drive control signal based on the first comparison result signal and keep the first drive control signal unchanged within the first predetermined time after the first comparison result signal changes. It can also output the second drive control signal based on the second comparison result signal and keep the second drive control signal unchanged within the second predetermined time after the second comparison result signal changes. The first drive control signal and the second drive control signal are inversely phased; and the first predetermined time can be equal to the second predetermined time.

[0096] In a specific implementation, the first output terminal of the pulse masking circuit 260 can be connected to the first input terminal of the comparator 250 to control the first preset threshold, and the second output terminal of the pulse masking circuit 260 can be connected to the second input terminal of the comparator 250 to control the second preset threshold.

[0097] In a specific implementation, the pulse masking circuit 260 may include a first latch, a second latch, a first pulse generator, and a second pulse generator. The input end of the first pulse generator is connected to the first output end of the comparator to receive the first comparison result signal, and the output end is connected to the clock end of the first latch to output the first clock signal; the data end of the first latch is connected to the first output end of the comparator to receive the first comparison result signal, the clock end is suitable for receiving the first clock signal, and the output end is suitable for outputting the first drive control signal based on the first comparison result signal and the first clock signal; the input end of the second pulse generator is connected to the second output end of the comparator to receive the second comparison result signal, and the output end is connected to the clock end of the second latch to output the second clock signal; the data end of the second latch is connected to the second output end of the comparator to receive the second comparison result signal, the clock end is suitable for receiving the second clock signal, and the output end is suitable for outputting the second drive control signal based on the second comparison result signal and the second clock signal.

[0098] In a specific implementation, the first pulse generator and the second pulse generator may further include a first buffer and a second buffer, respectively. The first buffer may allow the first comparison result signal to first reach the first latch and then reach the first pulse generator, and the input end of the first pulse generator is connected to the first output end of the comparator through the first buffer; the second buffer may allow the second comparison result signal to first reach the second latch and then reach the second pulse generator, and the input end of the second pulse generator is connected to the second output end of the comparator through the second buffer.

[0099] The first input terminal of the input terminal of the driving circuit 270 is connected to the first output terminal of the output terminal of the pulse masking circuit 260 to receive the first driving control signal, and the second input terminal of the input terminal of the driving circuit 270 is connected to the second output terminal of the output terminal of the pulse masking circuit 260 to receive the second driving control signal. The first output terminal of the output terminal of the driving circuit 270 is connected to the first coil 210 to provide the first driving signal thereto, and the second output terminal of the output terminal of the driving circuit 270 is connected to the second coil 220 to provide the second driving signal thereto. The first driving signal and the second driving signal are in opposite phases to each other.

[0100] In a specific implementation, the driving circuit 270 may have a first push-pull output structure and a second push-pull output structure.

[0101] The first push-pull output structure includes a buffer 271, a PMOS tube M3 and an NMOS tube M4. The input end of the buffer 271 is connected to the first output end of the pulse shielding circuit 260, and the output end is connected to the gates of M3 and M4. The sources of M3 and M4 are respectively connected to one of the positive power supply voltage (VDD) and the negative power supply voltage (-VDD) and the ground. The drains of M3 and M4 are commonly connected to the other end of the first coil 221 to drive it to generate an oscillation signal.

[0102] The second push-pull output structure includes a buffer 272, a PMOS tube M5 and an NMOS tube M6. The input end of the buffer 272 is connected to the second output end of the pulse shielding circuit 260, and the output end is connected to the gates of M5 and M6. The sources of M5 and M6 are respectively connected to the other of the positive power supply voltage (VDD) and the negative power supply voltage (-VDD) and the ground. The drains of M5 and M6 are commonly connected to the other end of the second coil 222 to drive it to generate an oscillation signal.

[0103] Through the first push-pull output structure and the second push-pull output structure, the output voltage of the driving circuit 270 can be made as close to the positive and negative power supply voltages as possible, thereby greatly improving the driving efficiency of the driving circuit 270 .

[0104] The magnetic modulation oscillation circuit 300 adopts a differentiator 240, a comparator 250, a pulse shielding circuit 260 and a driving circuit 270 with a differential structure, so that the power supply of the driving circuit 270 can not only be a bidirectional power supply (i.e., providing VDD and -VDD), but also a unidirectional power supply (such as only providing VDD or -VDD).

[0105] For example, when the power supply of the driving circuit 270 provides VDD, the voltages of the first driving signal and the second driving signal are one and the other of VDD and zero, and the differential signals of the two are VDD and -VDD, thereby realizing forward and reverse driving of the magnetic ring 210, so that the magnetic ring 210 can induce a periodically changing magnetic field strength along the hysteresis loop, and then generate an oscillation signal on at least one coil.

[0106] By providing a single-phase power supply, the magnetic modulation oscillation circuit 300 can be integrated into a single integrated circuit (IC) chip, which greatly reduces the volume of the magnetic modulation oscillation circuit 300 and facilitates the implementation of isolated current detection in a smaller space.

[0107] The magnetic ring 210, the first coil 221, the second coil 222, the sampling circuit 230, the differentiator 240, the comparator 250, the pulse shielding circuit 260, the drive circuit 270, the conductor 280, and the first and second buffers, the first and second pulse generators, and the first and second latches in the pulse shielding circuit 260 in the magnetic modulation oscillation circuit 300 have the same or similar structures and functions as the magnetic ring 110, the coil 120, the sampling circuit 130, the differentiator 140, the comparator 150, the pulse shielding circuit 160, the drive circuit 170, the conductor 180, and the buffer 161, the pulse generator 162 and the latch 163 in the pulse shielding circuit 160 in the magnetic modulation oscillation circuits 100 and 200, respectively, and reference may be made to the above description of these components.

[0108] Figure 7 400 is a flow chart of a method for driving a magnetic modulation oscillation circuit according to an embodiment of the present invention. The method 400 comprises the following steps:

[0109] Step a, collecting an oscillation signal at at least one coil and outputting a sampled signal;

[0110] Step b, processing the sampled signal and outputting a differential signal;

[0111] Step c, outputting a comparison result signal based on the comparison between the differential signal and a preset threshold;

[0112] Step d, outputting a drive control signal based on the comparison result signal and keeping the drive control signal unchanged for a predetermined period of time after the comparison result signal changes, wherein the drive control signal controls a preset threshold;

[0113] Step e: outputting a driving signal based on the driving control signal to enable at least one coil to generate an oscillation signal.

[0114] During the execution of step a, an oscillating signal at at least one coil wound on the magnetic ring may be sampled by a sampling circuit and a sampling signal (eg, a sampling current, a sampling voltage) may be output.

[0115] During the execution of step b, the rate of change of the sampling signal may be detected by a differentiator to output a differential signal.

[0116] During the execution of step c, a comparison result signal can be output by a comparator based on the comparison between the differential signal and a preset threshold, wherein the polarity of the preset threshold can be controlled by a driving control signal output by a pulse masking circuit, and the size of the preset threshold can be set by parameters of a feedback loop.

[0117] In the execution of step d, a drive control signal can be output based on the comparison result signal by a pulse masking circuit. The pulse masking circuit keeps the drive control signal unchanged within a predetermined time after the comparison result signal changes; after the predetermined time, the polarity and magnitude of the drive control signal output by the pulse masking circuit change with the change of the polarity or magnitude of the comparison result signal.

[0118] In a specific implementation, the predetermined time length may be greater than or equal to 10 microseconds and less than a half period of the oscillation signal.

[0119] In a specific implementation, a clock signal can be output based on the comparison result signal, for example, a pulse generator can be used to output the clock signal based on the comparison result signal; a drive control signal can be output based on the comparison result signal and the clock signal, for example, a latch can be used to output the drive control signal based on the comparison result signal and the clock signal.

[0120] During the execution of step e, a driving circuit may output a driving signal based on the driving control signal to enable at least one coil to generate an oscillation signal.

[0121] The method for driving the magnetic modulation oscillation circuit according to the embodiment of the present invention can be based on the above combination Figures 1 to 6 The magnetic modulation oscillator circuits 100, 200, and 300 are described and implemented. Therefore, the execution of each step in the method for driving the magnetic modulation oscillator circuit and the relationship between each step can refer to the above description of the magnetic modulation oscillator circuits 100, 200, and 300, which will not be repeated here.

[0122] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A magnetic modulation oscillation circuit, characterized in that: include: a magnetic ring adapted to allow at least one conductor through which a current to be measured can pass; at least one coil wound around the magnetic ring; a sampling circuit connected to one end of each coil of the at least one coil and adapted to output a sampling signal; a differentiator, whose input end is connected to the sampling circuit to receive the sampling signal and is suitable for outputting a differential signal; a comparator, whose input terminal is connected to the output terminal of the differentiator to receive the differential signal and is adapted to output a comparison result signal based on a comparison between the differential signal and a preset threshold value; a pulse masking circuit, whose input end is connected to the output end of the comparator to receive the comparison result signal, adapted to output a drive control signal and keep the drive control signal unchanged within a predetermined time after the comparison result signal changes; The pulse masking circuit comprises a pulse generator and a latch, wherein the input end of the pulse generator is connected to the output end of the comparator to receive the comparison result signal, the output end is connected to the clock end of the latch to output the clock signal, the data end of the latch is connected to the output end of the comparator to receive the comparison result signal, the clock end receives the clock signal, and the output end outputs the driving control signal based on the comparison result signal and the clock signal; The driving circuit has an input end connected to the output end of the pulse masking circuit to receive the driving control signal and an output end connected to the other end of each coil in the at least one coil to drive it to generate an oscillation signal.

2. The magnetic modulation oscillation circuit according to claim 1, characterized in that: The output end of the pulse masking circuit is connected to the input end of the comparator to control the preset threshold.

3. The magnetic modulation oscillation circuit according to claim 1, characterized in that: The predetermined time length is greater than or equal to 10 microseconds and less than a half period of the oscillation signal.

4. The magnetic modulation oscillation circuit according to claim 1, characterized in that: The at least one coil includes a coil, the sampling circuit includes a sampling resistor, one end of the sampling resistor is connected to one end of the coil and the input end of the differentiator, and the other end is connected to the ground, and the output end of the drive circuit is connected to the other end of the coil.

5. The magnetic modulation oscillation circuit according to claim 1, characterized in that: The pulse masking circuit further comprises a buffer, which is adapted to allow the comparison result signal to first reach the latch and then reach the pulse generator, and the input end of the pulse generator is connected to the output end of the comparator through the buffer.

6. The magnetic modulation oscillation circuit according to claim 1, characterized in that: The at least one coil comprises a first coil and a second coil, wherein: The sampling circuit comprises a sampling resistor, wherein a first end and a second end of the sampling resistor are respectively connected to one end of the first coil and one end of the second coil and are respectively adapted to output a first sampling signal and a second sampling signal; A first input terminal and a second input terminal of the differentiator are respectively connected to a first terminal and a second terminal of the sampling resistor to receive the first sampling signal and the second sampling signal and are respectively adapted to output a first differential signal and a second differential signal; A first input terminal and a second input terminal of the comparator are respectively connected to a first output terminal and a second output terminal of the differentiator to receive the first differential signal and the second differential signal and are respectively adapted to compare with a first preset threshold and a second preset threshold to output a first comparison result signal and a second comparison result signal; A first input terminal and a second input terminal of the pulse masking circuit are respectively connected to a first output terminal and a second output terminal of the comparator to receive the first comparison result signal and the second comparison result signal and are respectively adapted to output a first drive control signal and a second drive control signal, and respectively keep the first drive control signal and the second drive control signal unchanged within a first predetermined time length and a second predetermined time length after the first comparison result signal and the second comparison result signal are changed; The first input terminal and the second input terminal of the input terminal of the driving circuit are respectively connected to the first output terminal and the second output terminal of the output terminal of the pulse shielding circuit to receive the first driving control signal and the second driving control signal, and the first output terminal and the second output terminal of the output terminal of the driving circuit are respectively connected to the other end of the first coil and the second coil.

7. The magnetic modulation oscillation circuit according to claim 6, characterized in that: The first output terminal and the second output terminal of the pulse masking circuit are respectively connected to the first input terminal and the second input terminal of the comparator to respectively control the first preset threshold and the second preset threshold.

8. The magnetic modulation oscillation circuit according to claim 6, characterized in that: The pulse masking circuit comprises a first latch, a second latch, a first pulse generator and a second pulse generator, wherein: an input end of the first pulse generator is connected to a first output end of the comparator to receive the first comparison result signal, and an output end is connected to a clock end of the first latch to output a first clock signal; The data end of the first latch is connected to the first output end of the comparator to receive the first comparison result signal, the clock end receives the first clock signal, and the output end outputs a first driving control signal based on the first comparison result signal and the first clock signal; The input end of the second pulse generator is connected to the second output end of the comparator to receive the second comparison result signal, and the output end is connected to the clock end of the second latch to output a second clock signal; The data end of the second latch is connected to the second output end of the comparator to receive the second comparison result signal, the clock end receives the second clock signal, and the output end outputs a second driving control signal based on the second comparison result signal and the second clock signal.

9. The magnetic modulation oscillation circuit according to claim 8, characterized in that: The first pulse generator and the second pulse generator further include a first buffer and a second buffer, respectively, wherein: The first buffer is adapted to allow the first comparison result signal to first arrive at the first latch and then arrive at the first pulse generator, and the input end of the first pulse generator is connected to the first output end of the comparator through the first buffer; The second buffer is suitable for allowing the second comparison result signal to first reach the second latch and then reach the second pulse generator, and the input end of the second pulse generator is connected to the second output end of the comparator through the second buffer.

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