CN101286415B - A bidirectional sample and reset circuit for a current mutual inductor - Google Patents
A bidirectional sample and reset circuit for a current mutual inductor Download PDFInfo
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- CN101286415B CN101286415B CN2008100652495A CN200810065249A CN101286415B CN 101286415 B CN101286415 B CN 101286415B CN 2008100652495 A CN2008100652495 A CN 2008100652495A CN 200810065249 A CN200810065249 A CN 200810065249A CN 101286415 B CN101286415 B CN 101286415B
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Abstract
The invention relates to a two-way sampling and resetting circuit of a current transformer, comprising a CT primary side, a first reset resistor and two switch devices in which G polarities are connected with the same driving end; D polarities of the two switch devices are respectively connected with the two ends of the CT secondary side; wherein, the S polarity of the first switch device is connected with one end of the sampling resistor as a current sensing end, the other end of the sampling resistor is connected with a public ground phase, and the S polarity of the second switch device is connected with the public ground phase; whether the forward current or the reverse current of the CT secondary side is detected, the CT can be guaranteed to reset normally and effectively in condition of continuous reverse current by turning on and off the two switch devices synchronously; as the sampling current does not have circulation loop, large voltage peak can not be caused, and reverse saturation of the CT can also be avoided; the two-way sampling and resetting circuit of the current transformer can be applicable to various current sampling environment in which the reverse current is existed in transient state or steady state, such as synchronous rectification pressure reducing topology and two-stage composite topology adding a group of symmetrical topology ( a push-pull circuit, a half-bridge circuit and a full-bridge circuit).
Description
Technical field
The present invention relates to sampling and reset circuit, especially relate to a kind of current transformer bidirectional sample and reset circuit.
Background technology
Current transformer (current transformer is called for short CT) is a kind of current detecting magnetic device commonly used, and CT sampling commonly used and reset circuit are as shown in Figure 1.The two ends, former limit of CT are connected in series in the detected inlet highway among Fig. 1, and reset resistor R1 is connected in the secondary two ends of CT in parallel.The series arm that diode D1 and sampling resistor Rs form also is connected in the secondary two ends of current transformer CT in parallel.The forward current that detects the CT secondary is only considered in the design of this sampling and reset circuit, master power switch pipe Q1 blocking interval, and diode D1 ends, and R1 resets to CT by reset resistor.If the defective of its existence is during main switch Q1 opens reverse current to be arranged, and diode D1 ends, reverse current produces very big due to voltage spikes by bigger reset resistor R1, reset by sampling resistor Rs when resetting, the sampled signal of the current sense end Isense that is obtained by sampling resistor Rs is not actual current signal, and sampling resistor Rs is very little usually, make that forward voltage is lower when resetting, the CT magnetic core can not get active homing, it is oppositely saturated that repeatedly reverse current can cause the CT generation, influence the control circuit operate as normal, drive waveforms can get muddled.
Summary of the invention
Technical problem to be solved by this invention is to solve the defective that above-mentioned prior art exists, and proposes a kind of CT bidirectional sample and reset circuit.Not only can detect the forward current and the reverse current of CT secondary, and can guarantee that CT can effectively normally reset under the reverse current situation continuously.
Technical problem of the present invention is solved by the following technical programs.
This current transformer bidirectional sample and reset circuit comprise the former limit of the CT that is connected in series in the detected inlet highway, are connected in first reset resistor at CT secondary two ends in parallel.
The characteristics of this current transformer bidirectional sample and reset circuit are:
Be provided with two switching devices, the G utmost point of described two switching devices is connected with same drive end, the D utmost point is connected with described CT secondary two ends respectively, the S utmost point of first switching device is connected as the current sense end with an end of sampling resistor, the other end of described sampling resistor be connected publicly, the S utmost point of second switching device also with publicly is connected, during the master power switch pipe on the former limit of CT is opened, described first, two synchronous conductings of switching device, carry out current sample by sampling resistor, while forward excitation is when the master power switch pipe turn-offs, described first, two switching devices turn-off synchronously, are resetted by first reset resistor.
Technical problem of the present invention is solved by following further technical scheme.
Be provided with second reset resistor between CT secondary one end and public ground, when the master power switch pipe turn-offed, described first and second switching device turn-offed synchronously, is resetted by first and second reset resistor.
One end of described second reset resistor is connected with the D utmost point of second switching device that is connected CT secondary one end, the other end be connected publicly.
One end of described second reset resistor is connected with the D utmost point of first switching device that is connected CT secondary one end, the other end be connected publicly.Have no progeny when MOSFET closes, the current flowing branch road disconnects, and can produce the stress spike, increases the reset resistor part electric current of releasing, and can play the effect that reduces the stress spike.
Described switching device comprises N type channel mosfet, P type channel mosfet, NPN type switch triode, positive-negative-positive switch triode.
Preferably, described switching device is a N type channel mosfet.
The beneficial effect that the present invention is compared with the prior art is:
Bidirectional sample of the present invention and reset circuit adopt two switching devices to turn on and off synchronously, not only can detect the forward current and the reverse current of CT secondary, and the forward current or the reverse current that detect the CT secondary all can be by turning on and off two switching devices synchronously, make sample rate current form the loop and carry out current sample by two switching devices and sampling resistor, guarantee that CT can effectively normally reset under the reverse current situation continuously, can not cause very big due to voltage spikes because sample rate current does not have flow cycle, it is oppositely saturated to cause CT to take place.Bidirectional sample of the present invention and reset circuit go for various transient states or stable state exists in the current sample environment of reverse current, as synchronous rectification step-down (BUCK) topology and increase the compound topology of two-stage of one group of symmetry topology (recommend, half-bridge, full-bridge circuit).
Description of drawings
Fig. 1 is the sampling and the reset circuit figure of prior art;
Fig. 2 is bidirectional sample of the present invention and reset circuit figure;
Fig. 3 is the circuit diagram of the specific embodiment of the invention;
Fig. 4 is relevant voltage VgsQ1, VgsQ2, VgsQ3, the VgsQ4 oscillogram of Fig. 3 circuit;
Fig. 5 is that the switching tube of Fig. 3 circuit adopts bleeder circuit to obtain the circuit diagram (bidirectional sample and reset circuit do not draw) of driving voltage;
Fig. 6 is the bleeder circuit figure of Fig. 5 circuit:
Fig. 7 is that the switching tube of Fig. 3 circuit adopts sequence circuit to obtain the circuit diagram (bidirectional sample and reset circuit do not draw) of driving voltage;
Fig. 8 is that the reset resistor of Fig. 2 is connected the circuit diagram on another switching tube.
Embodiment
Below the contrast accompanying drawing and in conjunction with embodiment the present invention is further illustrated.
A kind of CT bidirectional sample and reset circuit that is used for synchronous rectification BUCK topology as shown in Figure 3, there is the transient state reverse current in the CT current sample of synchronous rectification BUCK topology.
The left side of Fig. 3 is CT bidirectional sample and a reset circuit as shown in Figure 2, and the right is a synchronous rectification BUCK topology.
CT bidirectional sample and reset circuit comprise the former limit of the CT that is connected in series in the detected inlet highway, are connected in first reset resistor R1 at CT secondary two ends in parallel.Adopt two switching devices: N type channel mosfet Q3 and N type channel mosfet Q4, their grid G is connected with same drive end Qdrive, drain D is connected with CT secondary two ends respectively, the source S of MOSFET Q3 is connected as current sense end Isense with the end of sampling resistor Rs, the other end of sampling resistor Rs is connected with public ground GND, and the source S of MOSFET Q4 also is connected with public ground GND.
As shown in Figure 2, also be provided with an end and be connected, second reset resistor R2 that the other end is connected with public ground GND with the drain D of MOSFET Q4.
Perhaps as shown in Figure 8, also be provided with an end and be connected, second reset resistor R2 that the other end is connected with public ground GND with the drain D of MOSFET Q3.
When no reverse current, when rectifying tube is that master power switch pipe Q1 is when opening, electric current begins to increase on the inductance L 1, the electric current that flows through on the CT is identical with it, MOSFET Q3, MOSFET Q4 and the synchronous conducting of master power switch pipe Q1, the CT secondary forms the loop by MOSFET Q4, sampling resistor Rs, MOSFET Q3, and sampling resistor Rs goes up the size of current on the former limit of voltage reflection CT.Master power switch pipe Q1 blocking interval, the electric current process continued flow switch pipe Q2 afterflow on the inductance L 1, the former limit of CT no current, MOSFET Q3, MOSFET Q4 turn-off, and by reset resistor R1, R2 CT are resetted.
If during continued flow switch pipe Q2 opens, the electric current on the inductance L 1 has begun oppositely, then situation and above-mentioned different.Continued flow switch pipe Q2 turn-offs, Q1 is open-minded for the master power switch pipe, reverse current on the inductance L 1 is transferred to master power switch pipe Q1 and the former limit of the CT that flows through from continued flow switch pipe Q2, MOSFET Q3, MOSFET Q4 and the synchronous conducting of master power switch pipe Q1, the CT secondary forms the loop by MOSFET Q4, sampling resistor Rs, MOSFET Q3, detect reverse current, the reverse excitation of while CT, this reverse current amplitude linearity reduces, if master power switch pipe Q1 service time long enough, the electric current on the inductance L 1 will be by oppositely transferring forward to.When master power switch pipe Q1 turn-offed, MOSFET Q3, MOSFET Q4 turn-offed synchronously, by reset resistor R1, R2 CT are resetted.
In the practical application, owing to have the dead band between master power switch pipe Q1 and the continued flow switch pipe Q2, when the current reversal on the inductance L 1, when continued flow switch pipe Q2 turn-offs, master power switch pipe Q1 is not open-minded as yet, but the reverse current on the inductance L 1 is flowed through CT to input by diode in the body of master power switch pipe Q1.If MOSFET is Q3, MOSFET Q4 and master power switch pipe Q1 are open-minded synchronously, then MOSFET Q3, MOSFET Q4 can't open in the dead band, CT produces very big reverse voltage by reset resistor R1, R2, cause CT weber in one or several cycle to add up to reach capacity, the reverse current peak value is big more then easy more saturated.Therefore the driving at MOSFET Q3, MOSFETQ4 should comprise that at least master power switch pipe Q1 opens and these two parts of dead band, and correspondent voltage VgsQ1, VgsQ2, VgsQ3, VgsQ4 waveform are as shown in Figure 4.
The driving of MOSFET Q3, MOSFET Q4 can adopt the Vds voltage of continued flow switch pipe Q2 to carry out suitable dividing potential drop and the sequential adjustment obtains, it drives driving pulsewidth and dead band part that pulsewidth has comprised rectifying tube Q1, also can carry out the sequential adjustment by the driving of continued flow tube Q2 and obtain.Its circuit diagram is respectively shown in Fig. 5,6,7.
If use MOSFET Q3, MOSFETQ4 instead P type channel mosfet, its bidirectional sample and the course of work that resets and above-mentioned explanation are roughly the same, can guarantee that equally CT can effectively normally reset under the reverse current situation continuously, can not cause very big due to voltage spikes because sample rate current does not have flow cycle, it is oppositely saturated to cause CT to take place.
Above content be in conjunction with concrete preferred implementation to further describing that the present invention did, can not assert that concrete enforcement of the present invention is confined to these explanations.For the general technical staff of the technical field of the invention, without departing from the inventive concept of the premise, can also make some simple deduction or replace, all should be considered as belonging to protection scope of the present invention.
Claims (5)
1. current transformer bidirectional sample and reset circuit comprise the former limit of the current transformer that is connected in series in the detected inlet highway, are connected in first reset resistor at current transformer secondary two ends in parallel, it is characterized in that:
Be provided with two switching devices, the G utmost point of described two switching devices is connected with same drive end, the D utmost point is connected with described current transformer secondary two ends respectively, the S utmost point of first switching device is connected as the current sense end with an end of sampling resistor, the other end of described sampling resistor be connected publicly, the S utmost point of second switching device also with publicly is connected, described first, during the synchronous conducting of two switching devices, carry out current sample by sampling resistor, while forward excitation, described first, when two switching devices turn-off synchronously, reset by first reset resistor.
2. current transformer bidirectional sample as claimed in claim 1 and reset circuit is characterized in that:
Between described current transformer secondary one end and public ground, be provided with second reset resistor, when described first and second switching device turn-offs synchronously, reset by first and second reset resistor.
3. current transformer bidirectional sample as claimed in claim 2 and reset circuit is characterized in that:
One end of described second reset resistor is connected with the D utmost point of second switching device that is connected current transformer secondary one end, the other end be connected publicly.
4. current transformer bidirectional sample as claimed in claim 2 and reset circuit is characterized in that:
One end of described second reset resistor is connected with the D utmost point of first switching device that is connected current transformer secondary one end, the other end be connected publicly.
5. as any described current transformer bidirectional sample and reset circuit in the claim 1 to 4, it is characterized in that:
Described switching device comprises N type channel mosfet, P type channel mosfet, NPN type switch triode, positive-negative-positive switch triode.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2008100652495A CN101286415B (en) | 2008-01-29 | 2008-01-29 | A bidirectional sample and reset circuit for a current mutual inductor |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2008100652495A CN101286415B (en) | 2008-01-29 | 2008-01-29 | A bidirectional sample and reset circuit for a current mutual inductor |
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| Publication Number | Publication Date |
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| CN101286415A CN101286415A (en) | 2008-10-15 |
| CN101286415B true CN101286415B (en) | 2011-01-05 |
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Families Citing this family (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102255513B (en) * | 2011-07-12 | 2013-05-08 | 深圳市核达中远通电源技术有限公司 | Bridge type synchronous rectification circuit |
| CN102426285B (en) * | 2011-09-14 | 2013-07-17 | 深圳航天科技创新研究院 | Current sensor used for bidirectional current sampling |
| CN104425120B (en) * | 2013-08-23 | 2016-07-06 | 台达电子工业股份有限公司 | Sample circuit for current transformer |
| CN103546048B (en) * | 2013-10-30 | 2018-03-06 | 华为技术有限公司 | Current sample method |
| CN105337260A (en) * | 2014-08-13 | 2016-02-17 | 中兴通讯股份有限公司 | Backward flowing current control method, backward flowing current control circuit and power converter |
| KR101637762B1 (en) * | 2014-12-04 | 2016-07-08 | 현대자동차주식회사 | Current sensing circuit |
| DE102017130422A1 (en) * | 2017-12-19 | 2019-06-19 | Phoenix Contact Gmbh & Co. Kg | Circuit for detecting reverse current in a voltage converter |
| CN110308315A (en) * | 2019-07-30 | 2019-10-08 | 广州金升阳科技有限公司 | A kind of current transformer sample circuit |
| CN110365216A (en) * | 2019-07-31 | 2019-10-22 | 上海军陶电源设备有限公司 | Current sampling circuit and full-bridge switching power supply circuit |
| CN111044772B (en) * | 2019-12-31 | 2022-05-20 | 广州金升阳科技有限公司 | Current sampling circuit and control method |
| CN112202330A (en) * | 2020-08-31 | 2021-01-08 | 杭州中恒电气股份有限公司 | Current detection circuit, power factor correction circuit and current detection method |
| CN113162421A (en) * | 2021-03-31 | 2021-07-23 | 西安麦格米特电气有限公司 | Power supply circuit and power supply equipment |
| CN113640565A (en) | 2021-07-26 | 2021-11-12 | 台达电子企业管理（上海）有限公司 | Current detection circuit, current detection method and converter |
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Owner name: POWER SUPPLY PRODUCTS (SHENZHEN) CO., LTD. Free format text: FORMER OWNER: AIMOSHENG NETWORK ENERGY SOURCE CO LTD Effective date: 20140903 |
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Effective date of registration: 20140903 Address after: 518101 Guangdong city of Shenzhen province Baoan District Xin'an road two North 68 Street office Honglang District Industrial Park plant Patentee after: Astec power supply (Shenzhen) Co., Ltd. Address before: 518057 Nanshan District science and Technology Industrial Park, Guangdong, Shenzhen Branch Road, No. Patentee before: Aimosheng Network Energy Source Co., Ltd. |