CN111555740A - Diode current bypass control circuit and control method thereof - Google Patents

Diode current bypass control circuit and control method thereof Download PDF

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Publication number
CN111555740A
CN111555740A CN202010608456.1A CN202010608456A CN111555740A CN 111555740 A CN111555740 A CN 111555740A CN 202010608456 A CN202010608456 A CN 202010608456A CN 111555740 A CN111555740 A CN 111555740A
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China
Prior art keywords
current
diode
tube
main
module
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CN202010608456.1A
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Chinese (zh)
Inventor
肖川
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Spin Tech (Shenzhen) Co.,Ltd.
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Shanghai Huirui Semiconductor Technology Co ltd
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Priority to CN202010608456.1A priority Critical patent/CN111555740A/en
Publication of CN111555740A publication Critical patent/CN111555740A/en
Priority to PCT/CN2020/114133 priority patent/WO2022000774A1/en
Priority to US18/011,527 priority patent/US20230284353A1/en
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
    • H03K17/16—Modifications for eliminating interference voltages or currents
    • H03K17/161—Modifications for eliminating interference voltages or currents in field-effect transistor switches
    • H03K17/165—Modifications for eliminating interference voltages or currents in field-effect transistor switches by feedback from the output circuit to the control circuit
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
    • H03K17/08—Modifications for protecting switching circuit against overcurrent or overvoltage
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
    • H03K17/08—Modifications for protecting switching circuit against overcurrent or overvoltage
    • H03K2017/0806—Modifications for protecting switching circuit against overcurrent or overvoltage against excessive temperature

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Abstract

The invention provides a diode current bypass control circuit and a control method thereof, wherein the control circuit comprises: the main module comprises a main switching tube and a main diode, and the main diode is connected in parallel with the source and drain ends of the main switching tube; the diode current sensing module is connected to two ends of the main diode and used for sensing current flowing through the main diode; the driving module is connected with the output end of the diode current sensing module and the grid end of the main switching tube and used for generating driving current proportional to the induced current to drive the main switching tube to be conducted; the main module, the diode current sensing module and the driving module form a negative feedback loop to reduce the current of the main diode to a set current value. The invention solves the problems of heating caused by the fact that large current flows through a body diode or a freewheeling diode in the turn-off period of a main switching tube and circuit runaway caused by the fact that the large current is introduced into a substrate in the prior art.

Description

Diode current bypass control circuit and control method thereof
Technical Field
The invention relates to the field of integrated circuits, in particular to a diode current bypass control circuit and a control method thereof.
Background
With the society paying more and more attention to high efficiency and environmental protection, power devices such as power MOSFETs, IGBTs, SiC, GaN and the like which continuously improve efficiency are continuously developed, and how to increase efficiency and reduce heat generation becomes the target of the efforts of engineers.
When power MOSFETs, IGBTs, SiC, GaN, etc. are used in power supplies or as main switching tubes, large currents are widely involved in flowing through body diodes or freewheeling diodes during the turn-off periods of these main switches; when the power MOSFET is used in a switching power supply, during switching, large current flows through a body diode of the power MOSFET; as in the battery of the portable device, during the overvoltage protection and the undervoltage protection of the MOSFET used for protection, the large current discharging and charging current will all flow through the body diode of the MOSFET separation device; in the application of high-efficiency and energy-saving direct current motor driving, a freewheeling diode is additionally added to a power switching tube such as IGBT/SiC/GaN and the like, so that current reaching tens of hundreds of amperes flows through the freewheeling diode when an upper bridge and a lower bridge drive main switching tube are turned off, and the motor is driven to normally work.
Because the large current flowing through the body diode or the fly-wheel diode usually causes heating, even logic confusion is caused by overlarge substrate current, the circuit can not work normally; therefore, how to reduce this negative effect has long been a direction that engineers are constantly searching for.
Disclosure of Invention
In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a diode current bypass control circuit and a control method thereof, which are used to solve the problems of heat generation caused by a large current flowing through a body diode or a freewheeling diode during a main switch off period and circuit runaway caused by the large current introduced into a substrate in the prior art.
To achieve the above and other related objects, the present invention provides a diode current bypass control circuit, comprising: a main module, a diode current induction module and a driving module,
the main module comprises a main switching tube and a main diode, and the main diode is connected in parallel with the source and the drain of the main switching tube;
the diode current sensing module is connected to two ends of the main diode and used for sensing current flowing through the main diode;
the driving module is connected to the output end of the diode current sensing module and the grid end of the main switching tube and used for generating a driving current proportional to the induced current to drive the main switching tube to be conducted;
the main module, the diode current sensing module and the driving module form a negative feedback loop to reduce the current of the main diode to a set current value.
Optionally, the diode current sensing module includes a sense diode, which induces the current flowing through the main diode through the sense diode by positively correlating the voltage across the sense diode with or equal to the voltage across the main diode.
Optionally, the diode current sensing module comprises: the non-inverting input end of the error amplifier is connected to the anode end of the main diode, the inverting input end of the error amplifier is connected to the source end of the source follower tube and the anode end of the sensing diode, the output end of the error amplifier is connected to the gate end of the source follower tube, the drain end of the source follower tube serves as the output end of the diode current sensing module, and the cathode end of the sensing diode is connected to the cathode end of the main diode.
Optionally, the diode current sensing module comprises: a bias current source, a first common-gate tube, a second common-gate tube, an inductive switch tube and an inductive diode, wherein the input end of the bias current source is connected with a power supply voltage, the output end of the bias current source is connected with the drain end of the first common-gate tube, the source end of the first common-gate tube is connected with the anode end of the main diode, the grid end of the first common grid tube is connected with the drain end of the first common grid tube and the grid end of the second common grid tube, the drain terminal of the second common-gate tube is used as the output terminal of the diode current sensing module, the source terminal of the second common-gate tube is connected with the source terminal of the sensing switch tube and the anode terminal of the sensing diode, the grid end of the induction switch tube is connected to the source end of the induction switch tube, and the drain end of the induction switch tube is connected to the cathode end of the induction diode and the cathode end of the main diode.
Optionally, the diode current sensing module further comprises: the first resistor is connected between the source end of the first common gate tube and the anode end of the main diode.
Optionally, the diode current sensing module further comprises: the first resistor is connected between the source end of the first common-gate tube and the anode end of the main diode, and the second resistor is connected between the source end of the second common-gate tube and the anode end of the sensing diode.
Optionally, the driving module comprises: first current mirror image pipe, second current mirror image pipe and drive resistor, the source end of first current mirror image pipe connect in the source end of second current mirror image pipe and connect into mains voltage, the drain terminal of first current mirror image pipe connect in the output of diode current induction module, the grid end of first current mirror image pipe connect in the drain terminal of first current mirror image pipe reaches the grid end of second current mirror image pipe, the drain terminal of second current mirror image pipe connect in drive resistor's one end, conduct simultaneously drive module's output, the other end of drive resistor inserts the on-off control signal of master switch pipe.
Optionally, the driving module comprises: the source end of the first current mirror image tube is connected with the source end of the second current mirror image tube and connected with a power voltage, the drain end of the first current mirror image tube is connected with the output end of the diode current induction module, the grid end of the first current mirror image tube is connected with the drain end of the first current mirror image tube and the grid end of the second current mirror image tube, the drain end of the second current mirror image tube is connected with one end of the sampling resistor, the grid end of the NMOS driving tube and the grid end of the PMOS driving tube, the other end of the sampling resistor is connected with the source end of the main switch tube, the drain end of the NMOS driving tube is connected with a power voltage, the source end of the NMOS driving tube is connected with the source end of the PMOS driving tube, and the output end of the driving module is connected with the grid end of the main switch tube, the drain end of the PMOS driving tube is connected to the source end of the main switching tube; and the threshold voltage of the PMOS driving tube is smaller than that of the main switching tube.
Optionally, the driving module further comprises: and the source end of the PMOS switching tube is connected with a power supply voltage, the drain end of the PMOS switching tube is connected with the grid end of the NMOS driving tube, and the grid end of the PMOS switching tube is connected with a switching control signal of the PMOS switching tube.
Optionally, the driving module comprises: the source end of the first current mirror image tube is connected with the source end of the second current mirror image tube and is connected with a power supply voltage, the drain end of the first current mirror image tube is connected with the output end of the diode current induction module, the grid end of the first current mirror image tube is connected with the drain end of the first current mirror image tube and the grid end of the second current mirror image tube, the drain end of the second current mirror image tube is connected with one end of the sampling resistor, the base electrode of the first triode and the base electrode of the second triode, the other end of the sampling resistor is connected with the source end of the main switch tube, the collector electrode of the first triode is connected with the power supply voltage, the emitter electrode of the first triode is connected with the emitter electrode of the second triode, and the emitter electrode of the first triode is connected with the grid end of the main switch tube as the output end of the driving module, the collector of the second triode is connected to the source end of the main switching tube; and the conduction voltage of the second triode is less than the threshold voltage of the main switching tube.
Optionally, the driving module further comprises: and the source end of the PMOS switching tube is connected with a power supply voltage, the drain end of the PMOS switching tube is connected to the base electrode of the first triode, and the grid end of the PMOS switching tube is connected with a switching control signal of the PMOS switching tube.
Optionally, the control circuit further comprises: and the current threshold module is connected between the diode current sensing module and the driving module and used for comparing an induced current with a set threshold current, closing the driving module when the induced current is smaller than the set threshold current, and opening the driving module when the induced current is larger than the set threshold current.
Optionally, the current threshold module comprises: the input end of the threshold current source is connected with the power supply voltage, and the output end of the threshold current source is connected with the output end of the diode current sensing module and the input end of the driving module.
The invention also provides a diode current bypass control method, which is used for performing bypass control on main diodes which are connected to the source and the drain of a main switch tube in parallel in a main module, and the control method comprises the following steps:
sensing a current flowing through the main diode based on a diode current sensing module;
the driving module generates a driving current proportional to the induced current according to the induced current so as to drive the main switching tube to be conducted;
the main module, the diode current sensing module and the driving module form a negative feedback loop to reduce the current of the main diode to a set current value.
Optionally, the method for sensing the current flowing through the main diode based on the diode current sensing module includes: the current flowing through the main diode is induced by positively correlating or equalizing the voltage across the induction diode in the diode current induction module with the voltage across the main diode.
Optionally, after the diode-based current sensing module senses the current flowing through the main diode, the control method further includes: comparing the induced current with a set threshold current, closing the driving module when the induced current is smaller than the set threshold current, and opening the driving module when the induced current is larger than the set threshold current.
As described above, according to the diode current bypass control circuit and the control method thereof of the present invention, the negative feedback loop constructed by the main module, the diode current sensing module and the driving module is utilized to control the main switching tube to be turned on to bypass and adjust the main diode current, so as to reduce the main diode current to the set current value, thereby controlling the main diode current within the limited range. The invention has negative feedback property, and can also add an opening threshold (namely setting threshold current) to automatically open or close the circuit.
Drawings
Fig. 1 shows an implementation manner of the diode current bypass control circuit according to an embodiment of the invention.
Fig. 2 shows another implementation of the diode current sensing module in the diode current bypass control circuit according to the present invention.
Fig. 3 shows another implementation of the driving module in the diode current bypass control circuit according to the present invention.
Fig. 4 shows another implementation of the driving module in the diode current bypass control circuit according to the present invention.
Fig. 5 shows another implementation manner of the driving module in the diode current bypass control circuit according to the present invention.
Fig. 6 shows another implementation of the driving module in the diode current bypass control circuit according to the present invention.
Fig. 7 shows an implementation of the diode current bypass control circuit according to the second embodiment of the present invention.
Description of the element reference numerals
101 main module
102 diode current sensing module
103 driving module
104 comparison detection module
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.
Please refer to fig. 1 to 7. It should be noted that the drawings provided in the present embodiment are only schematic and illustrate the basic idea of the present invention, and although the drawings only show the components related to the present invention and are not drawn according to the number, shape and size of the components in actual implementation, the form, quantity and proportion of the components in actual implementation may be changed arbitrarily, and the layout of the components may be more complicated.
Example one
As shown in fig. 1, the present embodiment provides a diode current bypass control circuit, which includes: a main module 101, a diode current sensing module 102 and a driving module 103,
the main module 101 comprises a main switching tube Mmain and a main diode Dmain, wherein the main diode Dmain is connected in parallel with the source and drain ends of the main switching tube Mmain;
the diode current sensing module 102 is connected to two ends of the main diode Dmain, and is configured to sense a current flowing through the main diode Dmain;
the driving module 103 is connected to the output end of the diode current sensing module 102 and the gate end of the main switching tube Mmain, and is configured to generate a driving current proportional to the induced current to drive the main switching tube Mmain to be turned on;
the main module 101, the diode current sensing module 102 and the driving module 103 form a negative feedback loop to reduce the current of the main diode Dmain to a set current value.
As an example, the main switching tube Mmain includes: the main diode Dmain is a body diode or a freewheeling diode of the main switching tube Mmain; of course, the main diode Dmain is specifically a body diode or a freewheeling diode, and the actual application needs to be considered.
As an example, the diode current sensing module 102 includes a sensing diode Dsns, which senses the current flowing through the main diode Dmain through the sensing diode Dsns by positively correlating the voltage across the sensing diode Dsns or equalizing the voltage across the main diode Dmain.
Specifically, as shown in fig. 1, in an example, the diode current sensing module 102 includes: an ERROR amplifier ERROR AMP, a source follower Md0 and a sense diode Dsns, wherein a non-inverting input terminal of the ERROR amplifier ERROR AMP is connected to an anode terminal of the main diode Dmain, a non-inverting input terminal of the ERROR amplifier ERROR AMP is connected to a source terminal of the source follower Md0 and an anode terminal of the sense diode Dsns, an output terminal of the ERROR amplifier ERROR AMP is connected to a gate terminal of the source follower Md0, a drain terminal of the source follower Md0 is used as an output terminal of the diode current sensing module 102, and a cathode terminal of the sense diode Dsns is connected to a cathode terminal of the main diode Dmain. The sensing diode Dsns and the main diode Dmain are diodes of the same type, and have different junction areas, the junction area ratio of the sensing diode Dsns to the main diode Dmain is 1/N, and N is a positive number.
In this example, the ERROR amplifier ERROR AMP and the source follower transistor Md0 form a negative feedback circuit, so that the voltage at the anode of the sense diode Dsns is equal to the voltage at the source of the main switch transistor Mmain, i.e. the voltage at the anode of the sense diode Dsns is equal to the voltage at the anode of the main diode Dmain, and since the cathode of the sense diode Dsns is connected to the cathode of the main diode Dmain, the voltage at the cathode of the sense diode Dsns is also equal to the voltage at the cathode of the main diode Dmain, so that the voltage at both ends of the sense diode Dsns is equal to the voltage at both ends of the main diode Dmain; at this time, the current ID _ main flowing through the main diode Dmain and the current ID _ sns flowing through the sense diode Dsns satisfy the following equation: ID _ sns: ID _ main ═ 1: n, thereby achieving accurate sensing of the current flowing through the main diode Dmain through the sensing diode Dsns.
Specifically, as shown in fig. 2, in another example, the diode current sensing module 102 includes: a bias current source Ibias, a first common-gate transistor MN0, a second common-gate transistor MN1, a sensing switch transistor Msns, and a sensing diode Dsns, the input end of the bias current source Ibias is connected with a power supply voltage VDD, the output end of the bias current source Ibias is connected with the drain end of the first common-gate tube MN0, the source end of the first common-gate transistor MN0 is connected to the anode end of the main diode Dmain, the gate end of the first common-gate tube MN0 is connected with the drain end of the first common-gate tube MN0 and the gate end of the second common-gate tube MN1, the drain terminal of the second common-gate transistor MN1 is used as the output terminal of the diode current sensing module 102, the source end of the second common-gate transistor MN1 is connected to the source end of the sensing switch transistor Msns and the anode end of the sensing diode Dsns, the gate end of the induction switch tube Msns is connected to the source end of the induction switch tube Msns, the drain terminal of the sensing switch tube Msns is connected to the cathode terminal of the sensing diode Dsns and the cathode terminal of the main diode Dmain. The induction switch tube Msns and the main switch tube Mmain are of the same type and are only different in size, the size ratio of the induction switch tube Msns to the main switch tube Mmain is 1/N, and N is a positive number.
In this example, the first common-gate transistor MN0 and the second common-gate transistor MN1 form a common-gate circuit, the source terminal voltage of the first common-gate transistor MN0 is regarded as a reference voltage, the source terminal voltage of the second common-gate transistor MN1 is regarded as a regulated voltage, the source terminal of the first common-gate transistor MN0 generates a voltage due to current flowing through the main diode Dmain, the sum of the voltage and the gate-source voltage of the first common-gate transistor MN0 is used as the gate voltage of the second common-gate transistor MN1, the second common-gate transistor MN1 generates current flowing through the sense diode Dsns under the bias of the gate voltage thereof, and as the current flowing through the sense diode Dsns increases, the source terminal voltage of the second common-gate transistor MN1 increases to be equal to the source terminal voltage of the first common-gate transistor MN0, so as to regulate the regulated voltage of the second common-gate transistor MN1 according to the reference voltage of the first common-gate transistor MN0, the regulated voltage is equal to the reference voltage, so that the source end voltage of the second common-gate transistor MN1 is always equal to the source end voltage of the first common-gate transistor MN0, namely the anode end voltage of the sensing diode Dsns is equal to the anode end voltage of the main diode Dmain, and meanwhile, as the cathode end of the sensing diode Dsns is connected with the cathode end of the main diode Dmain, the cathode end voltage of the sensing diode Dsns is equal to the cathode end voltage of the main diode Dmain, so that the voltages at the two ends of the sensing diode Dsns are equal to the voltages at the two ends of the main diode Dmain; at this time, the current ID _ main flowing through the main diode Dmain and the current ID _ sns flowing through the sense diode Dsns satisfy the following equation: ID _ sns: ID _ main ═ 1: n, thereby achieving accurate sensing of the current flowing through the main diode Dmain through the sensing diode Dsns.
Specifically, as shown in fig. 2, in another example, the diode current sensing module 102 further includes: a first resistor R0, the first resistor R0 is connected between the source terminal of the first common-gate transistor MN0 and the anode terminal Dmain of the main diode, and is used for introducing a corresponding dc component to fine tune the voltage relationship between the main diode Dmain and the sensing diode Dsns. Of course, the diode current sensing module 102 may further add a second resistor R1 to the first resistor R0, where the second resistor R1 is connected between the source terminal of the second common-gate transistor MN1 and the anode terminal of the sensing diode Dsns.
As an example, as shown in fig. 1 and 2, the driving module 103 includes: the driving circuit comprises a first current mirror image tube MP0, a second current mirror image tube MP1 and a driving resistor Rg, wherein the source end of the first current mirror image tube MP0 is connected with the source end of the second current mirror image tube MP1 and is connected with a power supply voltage VDD, the drain end of the first current mirror image tube MP0 is connected with the output end of the diode current induction module 102, the grid end of the first current mirror image tube MP0 is connected with the drain end of the first current mirror image tube MP0 and the grid end of the second current mirror image tube MP1, the drain end of the second current mirror image tube MP1 is connected with one end of the driving resistor Rg and is used as the output end Rg of the driving module 103, and the other end of the driving resistor is connected with a switch control signal Crl _ main of a main switch tube. It should be noted that the switching control signal Crl _ main of the main switching tube is a control signal generated by an external circuit, and is used for controlling the on/off of the main switching tube Mmain, so as to control whether the main switching tube Mmain is in an on period or an off period.
In this example, the first current mirror MP0 and the second current mirror MP1 constitute a current mirror for generating a driving current Idrv proportional to the induced current ID _ sns (the induced current ID _ sns and the driving current Idrv satisfy the following formula: Idrv is M _ ID _ sns, and M is an amplification factor of the current mirror), and the driving current Idrv is applied to the driving resistor Rg to generate a corresponding driving voltage to drive the main switch tube Mmain to be turned on, thereby implementing the turning on of the main switch tube Mmain in the off period.
As another example, as shown in fig. 3, the driving module 103 includes: a first current mirror tube MP0, a second current mirror tube MP1, a sampling resistor Rg, an NMOS drive tube MNdrv and a PMOS drive tube MPdrv, wherein a source terminal of the first current mirror tube MP0 is connected to a source terminal of the second current mirror tube MP1 and is connected to a power voltage VDD, a drain terminal of the first current mirror tube MP0 is connected to an output terminal of the diode current sensing module 102, a gate terminal of the first current mirror tube MP0 is connected to a drain terminal of the first current mirror tube MP0 and a gate terminal of the second current mirror tube MP1, a drain terminal of the second current mirror tube MP1 is connected to one end of the sampling resistor Rg, a gate terminal of the NMOS drive tube MNdrv and a gate terminal of the PMOS drive tube drv, the other end of the sampling resistor Rg is connected to a drain terminal of the main switch tube mmmain, a drain terminal of the NMOS drive tube MNdrv is connected to a power voltage, and a drain terminal of the PMOS drive tube MNdrv is connected to a source terminal of the PMOS drive tube MNdrv, meanwhile, the output end of the driving module 103 is connected to the gate end of the main switching tube Mmain, and the drain end of the PMOS driving tube MPdrv is connected to the source end of the main switching tube Mmain; the threshold voltage of the PMOS driving tube MPdrv is smaller than that of the main switching tube Mmain.
In this example, the first current mirror MP0 and the second current mirror MP1 form a current mirror for generating a driving current Idrv proportional to the induced current ID _ sns (where Idrv is M _ ID _ sns and M is an amplification multiple of the current mirror), and the driving current Idrv generates a corresponding driving voltage through the sampling resistor Rg to drive the NMOS driving tube MNdrv and the PMOS driving tube MPdrv to be turned on, so as to control the main switching tube Mmain to be turned on, thereby implementing the turning on of the main switching tube Mmain in the off period. Since the threshold voltage of the PMOS driving transistor MPdrv is smaller than the threshold voltage of the main switching transistor Mmain, the driving module 103 of this example has a current turn-off threshold, where the turn-off current threshold is a ratio of a difference between the threshold voltage of the main switching transistor Mmain and the threshold voltage of the PMOS driving transistor MPdrv to the sampling resistor Rg, that is, (Vth _ main-Vth _ MPdrv)/Rg.
As another example, as shown in fig. 4, compared to the previous example (i.e., the example shown in fig. 3), the driving module 103 of this example further includes: the source end of the PMOS switch tube MP is connected with a power supply voltage VDD, the drain end of the PMOS switch tube MP is connected with the grid end of the NMOS driving tube MNdrv, and the grid end of the PMOS switch tube MP is connected with a switch control signal Ctl _ MP of the PMOS switch tube. It should be noted that the switch control signal Ctl _ MP of the PMOS switch tube is an external control signal for controlling whether the NMOS drive tube MNdrv and the PMOS drive tube MPdrv are turned on, so as to realize external control of the driving module 103.
As another example, as shown in fig. 5, the driving module 103 includes: a first current mirror image tube MP0, a second current mirror image tube MP1, a sampling resistor Rg, a first triode NPN, and a second triode PNP, wherein a source end of the first current mirror image tube MP0 is connected to a source end of the second current mirror image tube MP1 and is connected to a power voltage VDD, a drain end of the first current mirror image tube MP0 is connected to an output end of the diode current sensing module 102, a gate end of the first current mirror image tube MP0 is connected to a drain end of the first current mirror image tube MP0 and a gate end of the second current mirror image tube MP1, a drain end of the second current mirror image tube MP1 is connected to one end of the sampling resistor Rg, a base of the first triode NPN, and a base of the second triode PNP, another end of the sampling resistor Rg is connected to the VDD of the main switch tube, a collector of the first triode NPN is connected to the power voltage, and an emitter of the first triode is connected to an emitter of the second triode PNP, meanwhile, the output end of the driving module 103 is connected to the gate end of the main switching tube Mmain, and the collector electrode of the second triode PNP is connected to the source end of the main switching tube Mmain; and the conduction voltage of the second triode PNP is less than the threshold voltage of the main switching tube Mmain.
In this example, the first current mirror MP0 and the second current mirror MP1 form a current mirror for generating a driving current Idrv proportional to the induced current ID _ sns (where Idrv is M _ ID _ sns and M is an amplification multiple of the current mirror), and the driving current Idrv generates a corresponding driving voltage through the sampling resistor Rg to drive the first triode NPN and the second triode PNP to be turned on, so as to control the main switch tube Mmain to be turned on, thereby implementing the turning on of the main switch tube Mmain in the turn-off period. Since the on-voltage of the second transistor PNP is smaller than the threshold voltage of the main switching tube Mmain, the driving module 103 of this example has a turn-off current threshold, where the turn-off current threshold is a ratio of a difference between the threshold voltage of the main switching tube Mmain and the voltage between the base and the emitter of the second transistor PNP to the sampling resistor Rg, that is, (Vth _ main-Vbe _ PNP)/Rg.
As another example, as shown in fig. 6, compared to the previous example (i.e., the example shown in fig. 5), the driving module 103 of this example further includes: the source end of the PMOS switch tube MP is connected with a power supply voltage VDD, the drain end of the PMOS switch tube MP is connected with the base electrode of the first triode NPN, and the grid end of the PMOS switch tube MP is connected with a switch control signal Ctl _ MP of the PMOS switch tube. It should be noted that the switch control signal Ctl _ MP of the PMOS switch tube is an external control signal for controlling whether the first triode NPN and the second triode PNP are turned on, so as to realize external control of the driving module 103.
Correspondingly, the present embodiment further provides a diode current bypass control method, which is used for performing bypass control on a main diode Dmain parallel connected to two ends of a source and a drain of a main switching tube Mmain in a main module 101, and the control method includes:
sensing a current flowing through the main diode Dmain based on the diode current sensing module 102;
the driving module 103 generates a driving current proportional to the induced current to drive the main switching tube Mmain to be conducted;
the main module 101, the diode current sensing module 102 and the driving module 103 form a negative feedback loop to reduce the current of the main diode Dmain to a set current value.
As an example, the method for sensing the Dmain current flowing through the main diode based on the diode current sensing module 102 includes: the sensing of the current flowing through the main diode Dmain is achieved by positively correlating the voltage across the sensing diode Dsns in the diode current sensing module 102 or by equalizing the voltage across the main diode Dmain.
The working principle of the diode current bypass control circuit according to this embodiment will be described in detail with reference to fig. 1, wherein the main switching tube Mmain is in an off period under the action of a switching control signal Ctl _ main of the main switching tube generated by an external circuit.
As shown in fig. 1, in the turn-off period of the main switching tube, the diode current sensing module 102 senses and detects the forward current of the main diode Dmain, and the driving module 103 amplifies the sensed current by M times and then forms a gate voltage at the gate terminal of the main switching tube Mmain through the driving resistor Rg, so as to drive the main switching tube Mmain to turn on the conduction current again in the turn-off period; at this time, the current flowing through the main switching tube Mmain is increased from zero at the time of turning off to ID _ Mmain, and since the total current flowing through the system is a fixed value at this operating moment, when the current flowing through the main switching tube Mmain is increased to ID _ Mmain, the current flowing through the main diode Dmain is decreased to ID _ Mmain; at this time, the induced current of the diode current sensing module 102 is reduced in an equal proportion, the driving module 103 amplifies the reduced induced current by M times and then forms a gate voltage at the gate end of the main switching tube Mmain through the driving resistor Rg, the smaller gate voltage reduces the current ID _ Mmain flowing through the main switching tube Mmain, and on the premise that the total system current is a fixed value, the current flowing through the main diode Dmain is increased, so as to form a negative feedback loop. The negative feedback loop will keep the whole loop in a steady state to reduce the forward current flowing through the main diode Dmain to a current set value; when the forward current flowing through the main diode Dmain is greater than the negative feedback loop turn-on current threshold (i.e., Vth _ main/Rg/M × N), the gate terminal voltage of the main switching tube Mmain is greater than the threshold voltage of the main switching tube Mmain, the main switching tube Mmain is turned on to realize that the main switching tube Mmain is turned on again in the turn-off period, and the main switching tube Mmain flows through the current ID _ Mmain, so that the forward current flowing through the main diode Dmain is reduced to a current set value; when the forward current flowing through the main diode Dmain is smaller than the negative feedback loop opening current threshold (namely Vth _ main/Rg/M × N), the gate terminal voltage of the main switching tube Mmain is smaller than the threshold voltage of the main switching tube Mmain, and the main switching tube Mmain is turned off, so that the main switching tube Mmain automatically restores to the off state in the off period.
The main module 101, the diode current sensing module 102 and the driving module 103 also constitute a self-adaptive acceleration response circuit, and the characteristic that the larger the current initially flowing through the main diode Dmain is, the faster the negative feedback loop response is, so as to bypass and reduce the current of the main diode Dmain to a set current value in a shorter time.
The above negative feedback loop reduces the forward current of the main diode Dmain to a current set-point, which is calculated as follows:
in design, when the negative feedback loop is turned on and reaches a steady state, the conduction current ID _ Mmain of the main switching tube Mmain which is turned on again in a selected turn-off period is much larger than the current flowing through the main diode Dmain the moment, that is, the working current flowing through the system at the moment is Isys, and almost all the working current flows through the main switching tube Mmain, and a very small part of the working current flows through the main diode Dmain. In the calculation, the current flowing through the main diode in this very small portion can be ignored. Taking the MOSFET power tube as the main switching tube Mmain as an example, when Isys current is small, and the source-drain voltage difference of the MOSFET power tube is greater than the overdrive voltage (Vgs-Vth), the MOSFET works in the saturation region. According to the relevant basic knowledge, at the moment:
Isys＝1/2*μn*Cox*W/L*(Vgs-Vth)2
Vgs＝Sqrt(2*Isys/(μn*Cox*W/L))+Vth
when the negative feedback reaches a steady state, the set value ID _ set of the current of the main diode Ddrain is as follows:
ID_set＝Vgs/Rg/M*N (1)
namely: ID _ set ═ (Sqrt (2 × Isys/(μ)n*Cox*W/L))+Vth)/Rg/M*N
According to the relevant basic knowledge, the forward voltage drop VD _ main of the main diode Dmain this case is:
VD_main＝VT*ln(ID_set/Is)
namely VD _ main ═ VT ═ ln ((Sqrt (2 ═ Isys/(μ))n*Cox*W/L))+Vth)/Rg/M*N/Is)
An example of a design is presented for ease of understanding. As shown in fig. 2, the area ratio of the main diode Dmain to the sense diode Dsns is 1E5 times (i.e. one hundred thousand times), the current amplification factor of the driving module 103 is 20 times, the resistance of the driving resistor is 50K ohms, and the system current is 10A at this time. Without the invention, the 10A current completely flows through the main diode Dmain in the turn-off period, so that the main diode Dmain generates heat, and the forward voltage drop of the large current 10A flowing through the main diode Dmain is large. Under the application of the invention, the main switching tube Mmain is turned on again, the width-length ratio of the main switching tube Mmain is usually very large, if the gate driving voltage is 3V at this time, the current flowing through the main diode Dmain the negative feedback loop is stable according to the above formula (1): ID _ set Vgs/Rg/M N3/50K/20E 5 is 300 mA.
Therefore, the current of 10A flows through the main diode Dmain before the application of the invention, so that the main diode Dmain generates heat; when the invention is applied, only 300mA current flows through the main diode Dmain when the negative feedback loop reaches a steady state, and the reduction effect of the main diode Dmain current is very obvious. Moreover, after the current of the main diode Dmain is changed from 10A to 300mA, the voltage drop of the main diode Dmain is conservatively estimated to be about 0.3V when the current of the main diode Dmain is reduced from 0.7V when the current of the main diode Dmain is 10A or more to 0.3V when the current of the main diode Dmain is 300mA, and the voltage difference between the source end and the drain end of the main switch tube Mmain which is connected in parallel with two ends of the main diode Dmain is also about 0.3V, namely the power consumption of the system is sharply reduced from the 7W power consumption generated by the forward voltage drop of 0.7V of the main diode Dmain the past to the 3W power consumption generated by the voltage drop of 0.3V when the main switch tube Mmain flows through 10A, so that the system efficiency is greatly improved and the.
As can be seen from the above examples, in the turn-off period of the main switching tube Mmain, if the main diode Dmain has a forward current flowing through it and exceeds a certain current threshold, the main switching tube Mmain is restarted to be turned on, most of the current flows away from the main switching tube Mmain by-pass, and only a very small current flows through the main diode Dmain; when the forward current of the main diode Dmain is smaller than the current threshold, the main switching tube Mmain is automatically recovered to be closed.
Example two
As shown in fig. 7, the present embodiment provides a diode current bypass control circuit, and compared with the first embodiment, the control circuit of the present embodiment further includes: a current threshold module 104, connected between the diode current sensing module 102 and the driving module 103, for comparing a sense current ID _ sns with a set threshold current Ith _ adj, and turning off the driving module 103 when the sense current ID _ sns is smaller than the set threshold current Ith _ adj, and turning on the driving module 103 when the sense current ID _ sns is larger than the set threshold current Ith _ adj.
As an example, as shown in fig. 7, the current threshold module 104 includes: the input end of the threshold current source is connected to a power supply voltage VDD, and the output end of the threshold current source is connected to the output end of the diode current sensing module 102 and the input end of the driving module 103.
In this example, when the sense current ID _ sns is smaller than a set threshold current Ith _ adj provided by the threshold current source, the sense current ID _ sns is cancelled by the set threshold current Ith _ adj, and at this time, the gate voltage of the first mirror current tube MP0 is always at a high level, that is, the first mirror current tube MP0 is in an off state, and then the driving module 103 is in an off state; at the moment, the bypass control circuit is in a dormant state, and the standby power consumption is very low. When the sense current ID _ sns is larger than the set threshold current Ith _ adj provided by the threshold current source, a current (i.e., a difference between the sense current ID _ sns and the set threshold current Ith _ adj) flows into the first mirror current pipe MP0, and the driving module 103 is in an on state. It should be noted that, when the diode current bypass control circuit includes the current threshold module 104, the set current value of the circuit is adjusted to (Vth _ main/Rg/M + Ith _ adj) × N due to the existence of the set threshold current Ith _ adj.
Correspondingly, the present embodiment further provides a diode current bypass control method, which is used for performing bypass control on a main diode Dmain parallel connected to two ends of a source and a drain of a main switching tube Mmain in a main module 101, and the control method includes:
sensing a current flowing through the main diode Dmain based on the diode current sensing module 102;
comparing a sense current ID _ sns with a set threshold current Ith _ adj based on a current threshold module 104, and turning off a driving module 103 when the sense current ID _ sns is less than the set threshold current Ith _ adj, and turning on the driving module 103 when the sense current ID _ sns is greater than the set threshold current Ith _ adj;
when the driving module 103 is turned on, the driving module 103 generates a driving current Idrv proportional to the induced current ID _ sns to drive the main switching tube Mmain to be turned on;
the main module 101, the diode current sensing module 102 and the driving module 103 form a negative feedback loop to reduce the current of the main diode Dmain to a set current value.
In summary, according to the diode current bypass control circuit and the control method thereof of the present invention, the negative feedback loop constructed by the main module, the diode current sensing module and the driving module is utilized to control the main switching tube to be turned on to bypass and adjust the main diode current, so as to reduce the main diode current to the set current value, thereby controlling the main diode current within the limited range. The invention has negative feedback property, and can also add an opening threshold (namely setting threshold current) to automatically open or close the circuit. Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.
The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.

Claims (16)

1. A diode current bypass control circuit, the control circuit comprising: a main module, a diode current induction module and a driving module,
the main module comprises a main switching tube and a main diode, and the main diode is connected in parallel with the source and the drain of the main switching tube;
the diode current sensing module is connected to two ends of the main diode and used for sensing current flowing through the main diode;
the driving module is connected to the output end of the diode current sensing module and the grid end of the main switching tube and used for generating a driving current proportional to the induced current to drive the main switching tube to be conducted;
the main module, the diode current sensing module and the driving module form a negative feedback loop to reduce the current of the main diode to a set current value.
2. The diode current bypass control circuit according to claim 1, wherein the diode current sensing module comprises a sense diode that induces the current flowing through the main diode by positively correlating or equalizing the voltage across the sense diode with the voltage across the main diode.
3. The diode current bypass control circuit of claim 2, wherein the diode current sensing module comprises: the non-inverting input end of the error amplifier is connected to the anode end of the main diode, the inverting input end of the error amplifier is connected to the source end of the source follower tube and the anode end of the sensing diode, the output end of the error amplifier is connected to the gate end of the source follower tube, the drain end of the source follower tube serves as the output end of the diode current sensing module, and the cathode end of the sensing diode is connected to the cathode end of the main diode.
4. The diode current bypass control circuit of claim 2, wherein the diode current sensing module comprises: a bias current source, a first common-gate tube, a second common-gate tube, an inductive switch tube and an inductive diode, wherein the input end of the bias current source is connected with a power supply voltage, the output end of the bias current source is connected with the drain end of the first common-gate tube, the source end of the first common-gate tube is connected with the anode end of the main diode, the grid end of the first common grid tube is connected with the drain end of the first common grid tube and the grid end of the second common grid tube, the drain terminal of the second common-gate tube is used as the output terminal of the diode current sensing module, the source terminal of the second common-gate tube is connected with the source terminal of the sensing switch tube and the anode terminal of the sensing diode, the grid end of the induction switch tube is connected to the source end of the induction switch tube, and the drain end of the induction switch tube is connected to the cathode end of the induction diode and the cathode end of the main diode.
5. The diode current bypass control circuit of claim 4, wherein the diode current sensing module further comprises: the first resistor is connected between the source end of the first common gate tube and the anode end of the main diode.
6. The diode current bypass control circuit of claim 4, wherein the diode current sensing module further comprises: the first resistor is connected between the source end of the first common-gate tube and the anode end of the main diode, and the second resistor is connected between the source end of the second common-gate tube and the anode end of the sensing diode.
7. The diode current bypass control circuit of claim 1, wherein the driver module comprises: first current mirror image pipe, second current mirror image pipe and drive resistor, the source end of first current mirror image pipe connect in the source end of second current mirror image pipe and connect into mains voltage, the drain terminal of first current mirror image pipe connect in the output of diode current induction module, the grid end of first current mirror image pipe connect in the drain terminal of first current mirror image pipe reaches the grid end of second current mirror image pipe, the drain terminal of second current mirror image pipe connect in drive resistor's one end, conduct simultaneously drive module's output, the other end of drive resistor inserts the on-off control signal of master switch pipe.
8. The diode current bypass control circuit of claim 1, wherein the driver module comprises: the source end of the first current mirror image tube is connected with the source end of the second current mirror image tube and connected with a power voltage, the drain end of the first current mirror image tube is connected with the output end of the diode current induction module, the grid end of the first current mirror image tube is connected with the drain end of the first current mirror image tube and the grid end of the second current mirror image tube, the drain end of the second current mirror image tube is connected with one end of the sampling resistor, the grid end of the NMOS driving tube and the grid end of the PMOS driving tube, the other end of the sampling resistor is connected with the source end of the main switch tube, the drain end of the NMOS driving tube is connected with a power voltage, the source end of the NMOS driving tube is connected with the source end of the PMOS driving tube, and the output end of the driving module is connected with the grid end of the main switch tube, the drain end of the PMOS driving tube is connected to the source end of the main switching tube; and the threshold voltage of the PMOS driving tube is smaller than that of the main switching tube.
9. The diode current bypass control circuit of claim 8, wherein the driver module further comprises: and the source end of the PMOS switching tube is connected with a power supply voltage, the drain end of the PMOS switching tube is connected with the grid end of the NMOS driving tube, and the grid end of the PMOS switching tube is connected with a switching control signal of the PMOS switching tube.
10. The diode current bypass control circuit of claim 1, wherein the driver module comprises: the source end of the first current mirror image tube is connected with the source end of the second current mirror image tube and is connected with a power supply voltage, the drain end of the first current mirror image tube is connected with the output end of the diode current induction module, the grid end of the first current mirror image tube is connected with the drain end of the first current mirror image tube and the grid end of the second current mirror image tube, the drain end of the second current mirror image tube is connected with one end of the sampling resistor, the base electrode of the first triode and the base electrode of the second triode, the other end of the sampling resistor is connected with the source end of the main switch tube, the collector electrode of the first triode is connected with the power supply voltage, the emitter electrode of the first triode is connected with the emitter electrode of the second triode, and the emitter electrode of the first triode is connected with the grid end of the main switch tube as the output end of the driving module, the collector of the second triode is connected to the source end of the main switching tube; and the conduction voltage of the second triode is less than the threshold voltage of the main switching tube.
11. The diode current bypass control circuit of claim 10, wherein the driver module further comprises: and the source end of the PMOS switching tube is connected with a power supply voltage, the drain end of the PMOS switching tube is connected to the base electrode of the first triode, and the grid end of the PMOS switching tube is connected with a switching control signal of the PMOS switching tube.
12. The diode current bypass control circuit according to any of claims 1 to 11, wherein the control circuit further comprises: and the current threshold module is connected between the diode current sensing module and the driving module and used for comparing an induced current with a set threshold current, closing the driving module when the induced current is smaller than the set threshold current, and opening the driving module when the induced current is larger than the set threshold current.
13. The diode current bypass control circuit of claim 12, wherein the current threshold module comprises: the input end of the threshold current source is connected with the power supply voltage, and the output end of the threshold current source is connected with the output end of the diode current sensing module and the input end of the driving module.
14. A diode current bypass control method is used for performing bypass control on main diodes connected to the source and the drain of a main switch tube in parallel in a main module, and is characterized by comprising the following steps:
sensing a current flowing through the main diode based on a diode current sensing module;
the driving module generates a driving current proportional to the induced current according to the induced current so as to drive the main switching tube to be conducted;
the main module, the diode current sensing module and the driving module form a negative feedback loop to reduce the current of the main diode to a set current value.
15. The diode current bypass control method of claim 14, wherein the method of sensing the current flowing through the main diode based on the diode current sensing module comprises: the current flowing through the main diode is induced by positively correlating or equalizing the voltage across the induction diode in the diode current induction module with the voltage across the main diode.
16. The diode current bypass control method of claim 14, wherein after the diode current sensing module senses the current flowing through the main diode, the control method further comprises: comparing the induced current with a set threshold current, closing the driving module when the induced current is smaller than the set threshold current, and opening the driving module when the induced current is larger than the set threshold current.
CN202010608456.1A 2020-06-29 2020-06-29 Diode current bypass control circuit and control method thereof Pending CN111555740A (en)

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PCT/CN2020/114133 WO2022000774A1 (en) 2020-06-29 2020-09-09 Diode current bypass control circuit and control method therefor
US18/011,527 US20230284353A1 (en) 2020-06-29 2020-09-09 Control circuit for bypassing diode current and control method

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2022000774A1 (en) * 2020-06-29 2022-01-06 上海汇瑞半导体科技有限公司 Diode current bypass control circuit and control method therefor

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2022000774A1 (en) * 2020-06-29 2022-01-06 上海汇瑞半导体科技有限公司 Diode current bypass control circuit and control method therefor

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