CN104600677A - Short-circuit protection method for transistor in control circuit - Google Patents
Short-circuit protection method for transistor in control circuit Download PDFInfo
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- CN104600677A CN104600677A CN201510016545.6A CN201510016545A CN104600677A CN 104600677 A CN104600677 A CN 104600677A CN 201510016545 A CN201510016545 A CN 201510016545A CN 104600677 A CN104600677 A CN 104600677A
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Abstract
The invention provides a short-circuit protection method for a transistor in a control circuit. The short-circuit protection method comprises the steps of acquiring induced electromotive force U at two ends of a section of a loop inductor of the circuit where the transistor is located, comparing the induced electromotive force U with pre-determined reference voltage Vref, enabling a transistor short-circuit protection circuit to output a control signal for controlling a drive signal of the transistor to change if the induced electromotive force U at two ends of the loop inductor is larger than the pre-determined reference voltage Vref, and enabling the transistor to be disconnected so as to achieve transistor short-circuit protection.
Description
Technical field
The invention belongs to electronic circuit field, particularly about the method for the transistor of the control circuit adopting coupled in parallel drive motors being carried out to short-circuit protection.
Background technology
In high-power low voltage motor controller architecture, the general mode of MOSFET multitube parallel that uses realizes power control circuit, when occurring abnormal in controller work, power capacitor positive pole and negative pole are by MOSFET short circuit, and MOSFET internal resistance is very little, be generally a few milliohm, impedance loop is PCB cabling and MOSFET internal resistance sum.Now loop peak electricity fails to be convened for lack of a quorum very high, and instantaneously more than the highest permission operating current of MOSFET, namely the rate of change of di/dt Current versus time can increase suddenly.Now do not protect and turn off MOSFET in time, MOSFET exceeds area of safety operaton and causes heating, and heating temp exceedes channel temperature and MOSFET thermal breakdown can be caused to damage.
Current Great Power Driver uses MOSFET multitube parallel mode to do in control circuit, does MOSFET short-circuit protection because operating current cannot use greatly sampling resistor to carry out current detecting, and the general mode of Hall current sensor that adopts gathers current flow control.But Hall element self response time is long, the time requirement of MOSFET short-circuit protection cannot be met, can only over-current detection be done.
Therefore, be necessary to provide a kind of method, when loop current is excessive, MOSFET pipe protected, prevent MOSFET thermal breakdown from damaging.
Summary of the invention
The object of the present invention is to provide one to protect MOSFET pipe when loop current is excessive, prevent the method that MOSFET thermal breakdown damages.
For reaching aforementioned object; the short-circuit protection method of transistor in a kind of control circuit of the present invention; it comprises the induced electromotive force U at the one section of loop inductance two ends gathering loop, transistor place; described induced electromotive force U and preset reference voltage Vref are compared; if the induced electromotive force U at described loop inductance two ends is greater than preset reference voltage Vref, then the drive singal of transistor short-circuit protection circuit output control signal control transistor makes transistor turn off.
According to one embodiment of present invention; adopt the induced electromotive force U at voltage comparator more described loop inductance two ends and described preset reference voltage Vref; when the induced electromotive force U at described loop inductance two ends is greater than preset reference voltage Vref; described voltage comparator exports control signal, makes transistor short-circuit protection circuit export the drive singal of aforementioned control transistor shutoff.
According to one embodiment of present invention, described preset reference voltage Vref is the inductance value L that the maximum permissible value of the electric current rate di/dt over time of described loop inductance after transistor turns is multiplied by described loop inductance.
According to one embodiment of present invention, described loop inductance is the inductance of one section of Copper Foil in the loop intercepted by the mode of copper foil leads.
According to one embodiment of present invention, described transistor short-circuit protection circuit exports the drive singal that control signal controls transistor, transistor cutoff conducting is specially and adopts pull down resistor to force transistor drive signal to drag down, make transistor cutoff conducting.
According to one embodiment of present invention, it comprises the scheduled time of setting transistor short-circuit protection further, when the transistor short-circuit protection time reaches the scheduled time, stops transistor short-circuit protection.
The method of detection inductance of the present invention does multitube parallel MOSFET short-circuit protection, and circuit realiration is simple, and detect the Current versus time rate of change linearity good, have higher accuracy, hardware cost is low, and the MOSFET short-circuit protection response time is adjustable, and reliability is high.
Accompanying drawing explanation
Fig. 1 is the circuit diagram of one embodiment of the present of invention.
Embodiment
Below in conjunction with accompanying drawing, specific embodiments of the invention are described.
Refer to shown in Fig. 1, the circuit diagram of its display one embodiment of the present of invention.In this embodiment, this control circuit is the control circuit of the motor for controlling jetting machine.As shown in Figure 1, six mosfet transistor composition three-phase bridge drive circuits are adopted in this control circuit.Wherein each phase drive circuit comprises two mosfet transistors be in series, two mosfet transistors of mutual series connection are connected with the both positive and negative polarity of power supply, when normally working, and two mosfet transistor alternate conduction of each phase, make a phase coil energising of motor, drive motors rotates.No longer describe in detail about the concrete principle of three-phase bridge drive circuit of mosfet transistor composition and working method herein.
As shown in Figure 1, when circuit occurs abnormal, power capacitor positive pole and negative pole are by Mosfet short circuit, and Mosfet internal resistance is very little, is generally a few milliohm, and impedance loop is PCB cabling and Mosfet internal resistance sum.Now peak electricity fails to be convened for lack of a quorum very high, and instantaneously more than the highest permission operating current of Mosfet, namely the rate of change of di/dt Current versus time can increase suddenly.Now do not protect and turn off Mosfet in time, Mosfet exceeds area of safety operaton and causes heating, and heating temp exceedes channel temperature and causes thermal breakdown to damage.
The present invention to be returned in electric capacity negative pole loop by motor to Mosfet at power capacitor positive pole and gets one section of loop inductance, intercepted by the mode of copper foil leads, wherein the loop inductance of this section of Copper Foil is fixed value L, the induced electromotive force U=L*di/dt of this loop inductance, because the inductance value L of loop inductance is fixed value, then by the induced electromotive force U at measuring loop inductance two ends, the rate of change di/dt=U/L of Current versus time in circuit can be calculated.Avoiding mosfet transistor heating temp to exceed channel temperature for protection mosfet transistor causes thermal breakdown to damage, and in circuit, the rate of change di/dt of Current versus time must be less than the maximum of the di/dt that mosfet transistor thermal breakdown allows.Because get one section of loop inductance inductance value L be fixed value, get the induced electromotive force U=L*di/dt at one section of loop inductance two ends, namely this induced electromotive force U is directly proportional to the rate of change di/dt of Current versus time in circuit, gather the induced electromotive force U at this section of loop inductance two ends, get final product the rate of change di/dt of the Current versus time in counter circuit.Can in initialization circuit the maximum of di/dt be multiplied by get the inductance value L Vref as the reference voltage of one section of loop inductance, by voltage comparator, the induced electromotive force U at this section of loop inductance two ends gathered and reference voltage Vref are compared, when the induced electromotive force U at loop inductance two ends is greater than reference voltage Vref, the rate of change of the Current versus time then represented in loop exceedes the rate of change maximum of allowed Current versus time, need to protect mosfet transistor, the drive singal of now MOSFET short-circuit protection circuit output control signal control MOSFET makes it change, make transistor cutoff conducting, transistor turns off, realize the short-circuit protection to transistor.Mosfet needs G pole drive circuit, and drive singal is generally PWM ripple one class, and high level is effective.Short-circuit protection circuit is that the operational amplification circuit output of voltage sample on inductance enters voltage comparator; voltage comparator output logic level can the G pole drive circuit signal (the G pole drive singal showing as Mosfet is forced to draw as low level) of positive closing Mosfet; after G pole drive singal is closed, Mosfet closes (showing as DS pole not conducting) and namely realizes Mosfet short-circuit protection function.
In MOSFET short-circuit protection circuit, can timer be set, the scheduled time of setting MOSFET short-circuit protection, when the MOSFET short-circuit protection time reaches the scheduled time, stops MOSFET short-circuit protection.
The three-phase bridge drive circuit be made up of MOSFET pipe in the aforementioned embodiment; also other transistors can be adopted in other embodiments to form drive circuit; its protective circuit method can be identical with the guard method of the drive circuit that aforementioned MOSFET pipe forms, illustrated exemplary explanation no longer one by one herein.
It should be noted that: above embodiment is only for illustration of the present invention and unrestricted technical scheme described in the invention, although this specification reference the above embodiments are to present invention has been detailed description, but, those of ordinary skill in the art is to be understood that, person of ordinary skill in the field still can modify to the present invention or equivalent replacement, and all do not depart from technical scheme and the improvement thereof of the spirit and scope of the present invention, all should be encompassed in right of the present invention.
Claims (6)
1. the short-circuit protection method of transistor in a control circuit; it is characterized in that: the method comprises the induced electromotive force U at the one section of loop inductance two ends gathering loop, transistor place; described induced electromotive force U and preset reference voltage Vref are compared; if the induced electromotive force U at described loop inductance two ends is greater than preset reference voltage Vref, then the drive singal of transistor short-circuit protection circuit output control signal control transistor makes transistor turn off.
2. the short-circuit protection method of transistor in control circuit according to claim 1; it is characterized in that: adopt the induced electromotive force U at voltage comparator more described loop inductance two ends and described preset reference voltage Vref; when the induced electromotive force U at described loop inductance two ends is greater than preset reference voltage Vref; described voltage comparator exports control signal, makes transistor short-circuit protection circuit export the drive singal of aforementioned control transistor shutoff.
3. the short-circuit protection method of transistor in control circuit according to claim 1, is characterized in that: described preset reference voltage Vref is the inductance value L that the maximum permissible value of the electric current rate di/dt over time of described loop inductance after transistor turns is multiplied by described loop inductance.
4. the short-circuit protection method of transistor in control circuit as claimed in claim 1, is characterized in that: described loop inductance is the inductance of one section of Copper Foil in the loop intercepted by the mode of copper foil leads.
5. the short-circuit protection method of transistor in control circuit as claimed in claim 1; it is characterized in that: described transistor short-circuit protection circuit exports drive singal that control signal controls transistor and transistor cutoff conducting is specially adopt pull down resistor to force transistor drive signal to drag down, make transistor cutoff conducting.
6. the short-circuit protection method of transistor in control circuit as claimed in claim 1, is characterized in that: it comprises the scheduled time of setting transistor short-circuit protection further, when the transistor short-circuit protection time reaches the scheduled time, stops transistor short-circuit protection.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510016545.6A CN104600677A (en) | 2015-01-14 | 2015-01-14 | Short-circuit protection method for transistor in control circuit |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201510016545.6A CN104600677A (en) | 2015-01-14 | 2015-01-14 | Short-circuit protection method for transistor in control circuit |
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| CN104600677A true CN104600677A (en) | 2015-05-06 |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105244848A (en) * | 2015-10-30 | 2016-01-13 | 杰华特微电子（杭州）有限公司 | Overvoltage protection method and circuit |
| CN106953624A (en) * | 2017-04-20 | 2017-07-14 | 天索（苏州）控制技术有限公司 | MOSFET parallel connection current foldback circuits |
| CN112839398A (en) * | 2019-11-25 | 2021-05-25 | 佛山市顺德区美的电热电器制造有限公司 | Electromagnetic heating device and dry burning detection method thereof |
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| JPH05344736A (en) * | 1992-06-10 | 1993-12-24 | Fuji Electric Co Ltd | Power regenerative control device |
| CN2268342Y (en) * | 1996-01-12 | 1997-11-19 | 顺德市龙江镇龙山艺峰变频器厂 | Variable-frequency speed regulator |
| CN2840437Y (en) * | 2005-08-30 | 2006-11-22 | 乔宗标 | A kind of short circuit over-current protection circuit of temperature self-adaptation |
| CN101702507A (en) * | 2009-11-04 | 2010-05-05 | 清华大学 | Method and device for essential safety anti-explosion based on dynamic monitoring and cut-off of electric spark |
| CN101820162A (en) * | 2010-05-18 | 2010-09-01 | 北京星网锐捷网络技术有限公司 | Overcurrent protector |
| CN102780198A (en) * | 2011-05-12 | 2012-11-14 | 上海联影医疗科技有限公司 | Overcurrent protection circuit |
-
2015
- 2015-01-14 CN CN201510016545.6A patent/CN104600677A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH05344736A (en) * | 1992-06-10 | 1993-12-24 | Fuji Electric Co Ltd | Power regenerative control device |
| CN2268342Y (en) * | 1996-01-12 | 1997-11-19 | 顺德市龙江镇龙山艺峰变频器厂 | Variable-frequency speed regulator |
| CN2840437Y (en) * | 2005-08-30 | 2006-11-22 | 乔宗标 | A kind of short circuit over-current protection circuit of temperature self-adaptation |
| CN101702507A (en) * | 2009-11-04 | 2010-05-05 | 清华大学 | Method and device for essential safety anti-explosion based on dynamic monitoring and cut-off of electric spark |
| CN101820162A (en) * | 2010-05-18 | 2010-09-01 | 北京星网锐捷网络技术有限公司 | Overcurrent protector |
| CN102780198A (en) * | 2011-05-12 | 2012-11-14 | 上海联影医疗科技有限公司 | Overcurrent protection circuit |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105244848A (en) * | 2015-10-30 | 2016-01-13 | 杰华特微电子（杭州）有限公司 | Overvoltage protection method and circuit |
| CN105244848B (en) * | 2015-10-30 | 2019-02-15 | 杰华特微电子（杭州）有限公司 | Over-voltage protection method and circuit |
| CN106953624A (en) * | 2017-04-20 | 2017-07-14 | 天索（苏州）控制技术有限公司 | MOSFET parallel connection current foldback circuits |
| CN106953624B (en) * | 2017-04-20 | 2023-10-13 | 天索（苏州）控制技术有限公司 | MOSFET parallel overcurrent protection circuit |
| CN112839398A (en) * | 2019-11-25 | 2021-05-25 | 佛山市顺德区美的电热电器制造有限公司 | Electromagnetic heating device and dry burning detection method thereof |
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Application publication date: 20150506 |
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