CN112636715A - FF (foundation field) bus passive regulator and parameter determination method - Google Patents
FF (foundation field) bus passive regulator and parameter determination method Download PDFInfo
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
- H03H7/38—Impedance-matching networks
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
- H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
- H02M3/06—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using resistors or capacitors, e.g. potential divider
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Abstract
The invention provides an FF bus passive regulator which comprises a first inductor L1 and a second inductor L2, wherein one end of the first inductor L1 and one end of the second inductor L2 are respectively coupled with the positive electrode and the negative electrode of a voltage-stabilized power supply, and the other end of the first inductor L1 and the other end of the second inductor L2 are coupled with an FF bus H1 network segment; the parameter determining method of the FF bus passive regulator comprises the steps of presetting an inductance value, making a corresponding Vout-f curve based on the preset inductance value, judging whether the preset inductance value meets the requirement of the terminal voltage Vout, and adjusting corresponding increase/decrease until the range of the inductance value is judged and confirmed; the FF bus passive regulator replaces an active scheme with the natural inductance isolation straight element characteristic, improves the ideal passive regulator, reduces the power consumption, keeps the good impedance characteristic of the ideal passive regulator, has few elements, simple and reliable circuits, forms a double-end balanced topology, and has strong anti-interference capability.
Description
Technical Field
The invention relates to the field of industrial automation field buses, in particular to an FF (foundation field) bus passive regulator and a parameter determination method thereof.
Background
In the field of automation, the two most widely used bus types in two-wire fieldbus are the FF fieldbus and the Profibus PA. The physical layer requirements for signal transmission are consistent for both buses. Both signals and power are transmitted simultaneously on a twisted pair shielded wire, the signals are transmitted by modulating an alternating current with a frequency of 31.25kHz, with a magnitude of ± 10mA, on the bus, which is converted into an alternating voltage by transformation at two termination impedances matched to the bus (these two termination impedances should be distributed across the bus, with a typical value of 100 Ω), so as to be received by other devices on the bus.
In FF fieldbus technology, the regulated power supply output must be regulated by an FF regulator to power the H1 network segment. The FF power regulator should not only ensure normal dc output, but also prevent fieldbus signals from being absorbed by the power supply and affecting bus communications.
To meet fieldbus communication requirements, the total impedance provided by the FF supply regulator should correspond to an inductive reactance that is no less than 5mH inductance. The traditional FF active regulator utilizes an active circuit of an operational amplifier to simulate ideal inductance, the simulation scheme is small in size and low in price, but the requirements on the operational amplifier speed slew rate are high, the requirements on resistance under the condition of high current are high, the balance performance and the common-mode interference resistance are poor, and the reliability during long-distance bus communication is difficult to guarantee.
However, for a common power supply, the ac impedance is very small, and if the bus is directly powered by the common power supply, most of the modulated ac current on the bus flows to the power supply with the smaller ac impedance, rather than the termination resistor, and the bus voltage is a relatively stable value, so that the purpose of superimposing an alternating signal on the bus cannot be achieved. In order to prevent the above phenomena, it is necessary to add a power supply regulator circuit between the power supply and the bus, and the function of the circuit is to provide a large ac impedance in the operating frequency range of the bus signal, which should be much larger than the matching termination impedance on the bus, so that most of the ac current modulated by the bus device flows to the matching termination impedance, thereby achieving the purpose of superimposing an ac voltage signal on the bus. On the other hand, a direct current path is provided for the power supply to supply a large current to the field device, and since the bus current may be large, in order to prevent the loss of efficiency of the power supply due to an excessive voltage drop on the direct current path, the direct current impedance should be as small as possible. The traditional FF active regulator utilizes the active circuit of an operational amplifier to simulate ideal inductance by combining the requirements of both signal and power supply. As shown in fig. 1 and 2, are two typical examples of active regulator applications.
However, the active regulator has the following disadvantages that the typical rate of bus signal transmission is 31.25kbit/s, the total inductance of the regulator circuit is required to be not less than 5mH in order to ensure that the waveform of the signal is not distorted, and the active operational amplifier circuit simulates actual inductance by using a resistance-capacitance element. The impedance expression is as follows: z ═ R1+ jw (R1 ═ R2 × (C1)), where L ═ R1 ═ R2 × (C1). The uF-level capacitor is used for simulating the mH-level inductor, so that the bandwidth with one order of magnitude difference needs to be compensated by the operational amplifier, and the requirement on the slew rate of the operational amplifier is high; secondly, when the bus has excessive current, in order to ensure the normal direct current output of the bus, the voltage drop on the R1 cannot be too large, so that the R1 must be small enough; in addition, due to the complex field environment of the FF bus, the interference rejection capability of the active filter also has certain problems. The above factors greatly limit the design and application of the active regulator, which is not favorable for improving the overall reliability of the product.
If an ideal passive regulator is adopted, as shown in fig. 3, the circuit schematic diagram of the ideal passive regulator is shown, wherein Lp is the inductor of the regulator, Rp is the series resistance of the regulator, RT and CT form bus terminals [ RT ═ 100 Ω, CT ═ 1uF ],
the AC impedance of the circuit is equivalent to
It can be seen that the ideal passive regulator utilizes the interaction of the LR circuit and the CR circuit at the terminal to eliminate the effect of frequency on the bus impedance, making it equivalent to a R resistance in the full frequency band range, and ensuring that the bus impedance is not affected by frequency fluctuations.
However, the actual inductance is not an ideal inductance, and due to the material characteristics of the inductance, the actual inductance changes with the frequency and the current; in addition, for the case that a plurality of devices are hung in one network segment, the topology can generate large voltage drop and power consumption on a 50 Ω resistor connected in series with an inductor, thereby affecting the normal operation of the whole network segment. For example, if a network segment hangs 32 devices and each device consumes 20mA of current, the total current consumption is 0.64A and the voltage drop across the resistor will be as high as 32V. This is obviously not allowed nor can it be used for engineering purposes.
Disclosure of Invention
The invention solves the technical problem of providing an FF bus passive regulator, which utilizes the natural characteristic of an inductance traffic-isolating direct-current element to replace an active scheme, improves the ideal passive regulator, thereby realizing the simulation of the ideal inductance, and uses the passive inductance element to ensure that the direct-current impedance is small, the alternating-current impedance is large, the circuit elements are few, the balance performance is good, the anti-interference capability is strong, and the overall reliability is high. The following technical scheme is adopted:
the first object of the present invention is to provide an FF bus passive regulator, which includes a first inductor L1 and a second inductor L2, where one end of the first inductor L1 and one end of the second inductor L2 are respectively used for coupling a positive electrode and a negative electrode of a regulated power supply, the other end of the first inductor L1 and the other end of the second inductor L2 are used for coupling an FF bus H1 network segment, and the FF bus H1 network segment includes 2 terminal impedances connected in parallel.
Further, the first inductor L1 and the second inductor L2 are both air-gap core inductors.
And the air gap magnetic core inductor is adopted, so that the direct current impedance of the inductor is smaller, and the loss of the power efficiency is reduced.
Further, the inductance values of the first inductor L1 and the second inductor are in the range of 1.9mH to 2.3 mH.
Inductors with inductance values in the range of 1.9mH to 2.3mH can meet the requirements of peak-to-peak value of the terminal voltage Vout and the rising/falling rate of Vout.
The second purpose of the invention is to provide a parameter determination method based on the FF bus passive regulator, which comprises the steps of S1, presetting an inductance value, and making a corresponding Vout-f curve based on the preset inductance value; s2, determining whether the preset inductance value meets the requirement of the terminal voltage Vout based on the Vout-f curve; s3, increasing/decreasing the inductance value based on the preset inductance value; s4, it is determined whether the requirement of the termination voltage Vout is satisfied based on increasing/decreasing the inductance value until the range of the inductance value of the inductor is confirmed.
Further, the requirements for the termination voltage Vout include requirements for Vout peak-to-peak and Vout rise/fall rates.
Further, the peak-to-peak value of Vout ranges from 0.4V to 0.6V.
Further, the Vout rise/fall rate is such that the voltage variation with frequency between 50Hz and 3kHz is between-20 dB per decade and 20dB per decade.
Furthermore, the direct current saturation resistance of the inductor is ensured based on the signal communication quality of the FF bus.
Further, the inductance decay with dc bias is less than 30%.
In the FF bus, the attenuation of the inductor along with the DC bias is lower than 30%, so that the anti-DC capacity saturation capacity of the inductor is ensured, and the signal communication of the FF bus is met.
The invention has the beneficial effects that:
1. the resistor connected in series with the ideal passive regulator is removed, the power consumption is greatly reduced, and the good impedance characteristic of the ideal passive regulator is maintained.
2. The passive regulator circuit is only composed of two inductors, so that the number of components is small, and the circuit is simple and reliable;
3. the double-end balanced topology is formed by utilizing the natural traffic isolation direct characteristic of the inductor, the anti-interference capability is strong, and the reliability is improved.
Drawings
Other features and advantages of the present invention will become apparent from the following description of the preferred embodiment, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention.
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the invention without limiting the invention.
In the drawings:
FIG. 1 is a schematic diagram of an active regulator circuit at low voltage;
FIG. 2 is a schematic diagram of the active regulator circuitry at high voltage;
FIG. 3 is a schematic circuit diagram of an ideal passive regulator;
FIG. 4 is a schematic circuit diagram of a FF bus passive regulator of the present invention;
FIG. 5 is a flowchart of an embodiment of a parameter determination method according to the present invention.
FIG. 6 is a block diagram of a Fieldbus Power supply test Specification FF-831 resonance test Specification;
fig. 7 is a graph of Vout-f when L is 3 mH;
FIG. 8 is a graph of the voltage waveforms for a FF bus passive regulator and an ideal passive regulator termination of the present invention;
FIG. 9 is a schematic diagram of introducing an air gap to improve the inductive reactance;
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Fig. 4 shows a schematic diagram of a FF bus passive regulator according to the present invention. The high-voltage power supply comprises a first inductor L1 and a second inductor L2, wherein one end of the first inductor L1 and one end of the second inductor L2 are respectively coupled with the positive electrode and the negative electrode of a power supply, and the other end of the first inductor L1 and the other end of the second inductor L2 are coupled with an FF bus H1 network segment and comprise two ends of 2 terminal impedances which are connected in parallel. And the first inductor and the second inductor both adopt air gap magnetic core inductors. Specifically, the inductance value range is 1.9mH-2.3mH, and the engineering requirement in the FF bus can be completely met. And only two inductors are adopted to form the passive regulator circuit, so that the number of components is small, and the circuit is simple and reliable.
In the FF bus system, a basic H1 segment consists of at least a power supply, regulator, and termination impedance. Where typical values of termination impedance are 100 omega and 1uF, across the bus, one placed near the end and the other placed far from the end, controlling the impedance on the bus to 50 omega. The power supply is typically nominally 24VDC and an FF regulator must be provided between the power supply and the H1 network segment to regulate the dc power supply and provide a high ac impedance to prevent fieldbus communication signals from entering the power supply. Meanwhile, since the FF bus supplies power at the same time, the dc impedance should be as small as possible to prevent the voltage drop on the dc channel from being too large.
In practical application of the topology circuit of the ideal passive regulator shown in fig. 3, the actual inductance changes with the frequency current, and a 50 Ω resistor generates a large voltage drop and power consumption, which affects the normal operation of the whole network segment, and thus, the actual engineering application cannot be performed.
The FF bus passive regulator provided by the invention can remove a 50 omega resistor and can keep the good impedance characteristic of an ideal passive regulator.
Based on the FF bus passive regulator, the invention also provides a parameter determining method for determining the inductance range in the FF bus wireless regulator.
The parameter determination method shown in the embodiments is further described below by using an actual operation example, so that those skilled in the art can better understand the technical scheme of the present invention.
As shown in fig. 5, which is a flowchart of a method according to an embodiment of the present invention, the method includes the following steps:
s1, presetting an inductance value, and making a corresponding Vout-f curve based on the preset inductance value
In this embodiment, the predetermined inductance value is 3mH, and the test is performed according to the block diagram of the fieldbus power supply test specification FF-831 resonance test specification shown in fig. 6, so as to obtain the Vout-f curve when L is 3mH as shown in fig. 7.
And S2, determining whether the preset inductance value meets the requirement of the terminal voltage Vout based on the Vout-f curve.
The field bus power supply test specification FF-8315.4 section resonance test puts a definite requirement on the field bus impedance, and the peak-to-peak value of the voltage Vout of the bus terminal in the frequency range of 3kHz-39kHz must be within 0.4V-0.6V. Besides the requirement of ensuring the voltage of the output terminal, the voltage roll-off rate, namely the rising/falling rate of the Vout, needs to be ensured, and the rising/falling rate of the Vout needs to meet the requirement that the change rate of the voltage along with the frequency between 50Hz and 3kHz is between-20 dB per decade and 20dB per decade.
For the frequency range of 3kHz-39kHz, the peak-to-peak value of the terminal voltage of L-3 mH meets the requirement of the specification, but does not meet the requirement of the voltage roll-off rate.
S3, increasing/decreasing the inductance value based on the preset inductance value
As the inductance L decreases or increases, the termination voltage also shifts. In this embodiment, the inductance value is adjusted to be increased or decreased based on the inductance value of 3 mH. Vout will be below 0.4V when L1.9 mH, f 3kHz, Vout will exceed 0.6V when L4 mH.
S4, it is determined whether the requirement of the termination voltage Vout is satisfied based on increasing/decreasing the inductance value until the range of the inductance value of the inductor is confirmed.
In the embodiment, the obtained inductance value range is 1.9mH-2.3mH, the FF bus standard can be met, the good impedance characteristic is kept in the range, and the influence of voltage drop on a 50 omega resistor and power consumption is eliminated and the good bus impedance is ensured to a certain extent. As shown in fig. 8, when L is 1.9mH to 2.3mH, the terminal voltage simulation result comparison graph of the FF bus passive regulator and the ideal passive regulator of the present invention shows that the error is less than 0.1V, which meets the actual design requirement.
In addition, the inductor is connected in series in the power circuit and needs to bear a certain direct current, so that the inductor has direct current saturation resistanceAnd (5) determining the requirements. The relative permeability μ of an actual magnetic material due to the properties of the magnetic material itselfrWill be attenuated with the increase of current and will be measured by inductance
The formula shows that the increase of the current can cause the attenuation of the inductance, thereby causing the change of the bus impedance, and the change of the impedance can cause the change of the amplitude of the FF signal. To eliminate this effect and ensure the uniformity of FF bus impedance, the dc resistance of the inductor can be increased by opening a certain air gap, as shown in fig. 9. The BH curve of the air gap-free magnetic material is steep, the magnetic material is quickly saturated under the condition of introducing certain direct current, a hysteresis loop is inclined after an air gap is added, the nonlinear part of the magnetic material is compensated by linear air, the magnetic field strength H can be extended to a wider range, and the larger magnetic field strength H represents larger direct current endurance I according to the ampere loop law Hl-NI. Therefore, the addition of a proper air gap can have a great effect on the DC resistance of the inductor. In order to meet the requirement of signal communication quality of the FF bus, the attenuation of the inductor along with the DC bias is required to be ensured to be lower than 10-30%.
Finally, it should be noted that: it should be understood that the above examples are only for clearly illustrating the present invention and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications of the invention may be made without departing from the scope of the invention.
Claims (9)
1. A FF bus passive regulator is characterized in that,
the circuit comprises a first inductor L1 and a second inductor L2, wherein one end of the first inductor L1 and one end of the second inductor L2 are respectively coupled with the positive electrode and the negative electrode of a regulated power supply, the other end of the first inductor L1 and the other end of the second inductor L2 are respectively coupled with an FF bus H1 network segment, and the FF bus H1 network segment comprises 2 terminal impedances connected in parallel.
2. The FF bus passive regulator of claim 1, wherein the first inductor L1 and the second inductor L2 are both air-gap core inductors.
3. The FF bus passive regulator of any of claims 1-2, wherein the first inductor L1 and the second inductor have an inductance value in the range of 1.9mH-2.3 mH.
4. A parameter determination method based on the FF bus passive regulator of any of claims 1-3, comprising,
s1, presetting an inductance value, and making a corresponding Vout-f curve based on the preset inductance value;
s2, determining whether the preset inductance value meets the requirement of the terminal voltage Vout based on the Vout-f curve;
s3, increasing/decreasing the inductance value based on the preset inductance value;
s4, it is determined whether the requirement of the termination voltage Vout is satisfied based on increasing/decreasing the inductance value until the range of the inductance value of the inductor is confirmed.
5. The parameter determination method of claim 4, wherein the requirements for the terminal voltage Vout include requirements for Vout peak-to-peak and terminal voltage Vout rise/fall rates.
6. The parameter determination method of claim 5, wherein the peak-to-peak Vout range is 0.4V to 0.6V.
7. The parameter determination method according to claim 5, wherein the terminal voltage Vout rise/fall rate is such that the voltage variation with frequency between 50Hz and 3kHz is between-20 dB per decade and 20dB per decade.
8. The parameter determination method of claim 4, further comprising validating inductance parameters to ensure dc saturation resistance of the inductance based on FF bus signal communication quality.
9. The parametric determination of claim 8, wherein the inductance parameter is a decay of inductance with dc bias of less than 30%.
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| GB201014508D0 (en) * | 2009-09-01 | 2010-10-13 | Fisher Rosemount Systems Inc | Integrated bus controller and power supply device for use in a process control system |
| CN104716953A (en) * | 2014-12-31 | 2015-06-17 | 浙江中控技术股份有限公司 | Two-wire system field bus power decoupling circuit |
| WO2016045766A1 (en) * | 2014-09-22 | 2016-03-31 | Sew-Eurodrive Gmbh & Co. Kg | Arrangement for data transmission via a data bus and method for data transmission in an arrangement for data transmission via a data bus |
| US10797513B1 (en) * | 2019-04-08 | 2020-10-06 | Abb Schweiz Ag | Technologies for interactive predictive control of uninterruptible power supply systems |
-
2020
- 2020-12-02 CN CN202011392338.8A patent/CN112636715B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4768002A (en) * | 1987-02-24 | 1988-08-30 | Triad Microsystems, Inc. | Power filter resonant frequency modulation network |
| WO2004073373A2 (en) * | 2003-02-19 | 2004-09-02 | Pepperl + Fuchs Gmbh | Pseudo isolated power conditioner |
| CN101231783A (en) * | 2007-01-22 | 2008-07-30 | 罗斯蒙特雷达液位股份公司 | Field bus interface |
| GB201014508D0 (en) * | 2009-09-01 | 2010-10-13 | Fisher Rosemount Systems Inc | Integrated bus controller and power supply device for use in a process control system |
| WO2016045766A1 (en) * | 2014-09-22 | 2016-03-31 | Sew-Eurodrive Gmbh & Co. Kg | Arrangement for data transmission via a data bus and method for data transmission in an arrangement for data transmission via a data bus |
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