CN114123737A - System and method for reducing power loss of MOSFET (metal-oxide-semiconductor field effect transistor) - Google Patents

System and method for reducing power loss of MOSFET (metal-oxide-semiconductor field effect transistor) Download PDF

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Publication number
CN114123737A
CN114123737A CN202111293828.7A CN202111293828A CN114123737A CN 114123737 A CN114123737 A CN 114123737A CN 202111293828 A CN202111293828 A CN 202111293828A CN 114123737 A CN114123737 A CN 114123737A
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Prior art keywords
mosfet
signal
circuit
driving signal
voltage
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CN202111293828.7A
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Chinese (zh)
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张东来
朱雪丽
高伟
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Shenzhen Graduate School Harbin Institute of Technology
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Shenzhen Graduate School Harbin Institute of Technology
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
    • H02M1/088—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the simultaneous control of series or parallel connected semiconductor devices

Abstract

The invention provides a system for reducing MOSFET power loss, which comprises an MOSFET to be driven, a differential sampling circuit, a voltage comparator, a logic circuit for realizing an OR gate and an MOSFET driving circuit, wherein the differential sampling circuit collects a voltage signal between a drain electrode and a source electrode of the MOSFET to be driven, the voltage comparator judges the polarity of the voltage signal to obtain an MOSFET compensation driving signal, the MOSFET compensation driving signal and an MOSFET original driving signal are input to the logic circuit for realizing the OR gate to obtain an MOSFET correction driving signal, the MOSFET correction driving signal is input to the MOSFET driving circuit, and the MOSFET is driven by the MOSFET driving circuit. The invention also provides a method for reducing the power loss of the MOSFET. The invention has the beneficial effects that: the invention uses the reverse follow current of the MOSFET channel to replace the body parasitic diode follow current, and reduces the power loss of the MOSFET by reducing the conduction time of the body parasitic diode, thereby reducing the junction temperature and improving the reliability of the switch tube and the circuit.

Description

System and method for reducing power loss of MOSFET (metal-oxide-semiconductor field effect transistor)
Technical Field
The present invention relates to power switches, and more particularly to a system and method for reducing power loss of a MOSFET.
Background
The loss of the power switch device mainly comprises switching loss and conduction loss, wherein the switching loss is related to the switching frequency, the switching-on time and the switching-off time of the power switch device, and the voltage and the current before and after the switching, and the conduction loss is related to the conduction voltage drop, the current flowing through and the conduction time of the power switch device. On one hand, the power loss affects the efficiency of the whole system, and on the other hand, the power device generates high heat, so that the temperature of the power device is increased, and the reliability and the service life of the device are affected. Due to its advantages, MOSFETs are widely used in various power electronic converters and systems, and can be classified into three stable states during normal operation: a forward on state, a reverse freewheeling state, and a forward blocking state.
There is a body parasitic diode between the source and drain of the MOSFET, and when the system is a resistive-inductive load (such as a motor or other high-power load), the MOSFET has an operating state in which the body parasitic diode freewheels. When the body parasitic diode of the MOSFET is conducted, the terminal voltage of the body parasitic diode is larger, so that the power loss of the MOSFET is larger, and the junction temperature is higher. The MOSFET can freewheel in reverse direction through the body parasitic diode, as well as through the channel. The MOSFET has small channel resistance, small channel voltage and the same channel resistance in forward conduction and reverse conduction, so that the power loss after reverse freewheeling by using the channel is smaller than that after freewheeling by using a body parasitic diode. The power electronic converter can only contain a single MOSFET, such as various DC-DC converters; there may also be multiple MOSFETs, such as synchronous rectification topologies, half-bridge circuits, single-phase full-bridge circuits, three-phase full-bridge circuits, etc. In a bridge circuit, a dead time is usually provided in order to avoid a straight-through of upper and lower tubes of a bridge arm. The size of the dead time is related to factors such as the size of a load, the type of the MOSFET and the like, and if the fixed dead time is set, the dead time can be set too long, so that larger power loss and harmonic signals are caused; the situation that the dead time is set too short and the situation that the upper pipe and the lower pipe of the bridge arm are directly connected cannot be completely avoided can also occur. When the MOSFET in these circuits is in the body parasitic diode freewheeling state, the power consumption of the MOSFET is large, and the junction temperature is high after long-term operation.
Therefore, how to reduce the power loss of the MOSFET is an urgent technical problem to be solved by those skilled in the art.
Disclosure of Invention
To solve the problems of the prior art, the present invention provides a system and method for reducing power loss of a MOSFET.
The invention provides a system for reducing MOSFET power loss, which comprises an MOSFET to be driven, a differential sampling circuit, a voltage comparator, a logic circuit for realizing an OR gate and an MOSFET drive circuit, wherein the differential sampling circuit collects a voltage signal V between a drain electrode and a source electrode of the MOSFET to be drivenDSAnd output to a voltage comparator, which determines a voltage signal VDSAnd (3) obtaining a MOSFET compensation driving signal, inputting the MOSFET compensation driving signal and the MOSFET original driving signal to a logic circuit for realizing an OR gate to obtain a MOSFET correction driving signal, inputting the MOSFET correction driving signal to a MOSFET driving circuit, and driving the MOSFET through the MOSFET driving circuit.
The invention also provides a method for reducing the power loss of the MOSFET, which comprises the following steps:
step 1: differential sampling circuit is used for collecting voltage signals V at two ends of drain and source of MOSFET to be drivenDSAnd applying the voltage signal VDSOutputting the voltage to a voltage comparator;
step 2: judging the voltage signal V by a voltage comparatorDSTo obtain a compensation driving signal of the MOSFET, and if a voltage signal V at two ends of the MOSFET is detectedDSIf the output signal is less than 0, the MOSFET compensation driving signal is given as '1', otherwise, the MOSFET compensation driving signal is given as '0', wherein '1' represents the MOSFET turn-on signal, and '0' represents the MOSFET turn-off signal;
step 3: inputting the MOSFET compensation driving signal and the MOSFET original driving signal of the system into a logic circuit for realizing an OR gate, and obtaining an MOSFET correction driving signal by taking the logical relation of OR by the logic circuit for realizing the OR gate;
step 4: the MOSFET correction drive signal is output to a MOSFET drive circuit, and the MOSFET is driven by the MOSFET drive circuit.
The invention has the beneficial effects that: the invention uses the reverse follow current of the MOSFET channel to replace the body parasitic diode follow current, and reduces the power loss of the MOSFET by reducing the conduction time of the body parasitic diode, thereby reducing the junction temperature and improving the reliability of the switch tube and the circuit.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other solutions can be obtained according to the drawings without inventive efforts.
FIG. 1 is a schematic diagram of the driving signals and the currents flowing through the upper and lower MOSFETs of the same bridge arm according to the present invention.
Fig. 2 is a system block diagram of a system for reducing MOSFET power loss in accordance with the present invention.
Detailed Description
It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.
In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate orientations or positional relationships based on those shown in the drawings, and are used merely for convenience in describing the present invention and for simplicity in description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore, should not be taken as limiting the scope of the present invention. Furthermore, the terms "first", "second", etc. are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first," "second," etc. may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless otherwise specified.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art through specific situations.
The invention is further described with reference to the following description and embodiments in conjunction with the accompanying drawings.
In order to solve the problems in the prior art, the invention provides a system and a method for reducing power loss of a MOSFET (metal-oxide-semiconductor field effect transistor), which can reduce the power loss of the MOSFET according to the voltage V at two ends of a drain stage and a source stage of the MOSFETDSThe polarity of the MOSFET is combined with an original drive signal of the MOSFET of the system, and the reverse follow current of the MOSFET channel is used for replacing the follow current of the body parasitic diode, so that the power loss of the MOSFET is reduced by reducing the conduction time of the body parasitic diode.
The on-current direction of a MOSFET (metal-oxide semiconductor field effect transistor, abbreviated as MOSFET) is related to the load current direction, and when the load of the system is a resistive-inductive load, the MOSFET has an operating state in which it freewheels in the reverse direction. For the same bridge arm of the bridge circuit, logic driving signals with complementary conduction of the upper and lower tubes are usually designed, but in order to avoid the situation that the upper and lower tubes are in through connection, dead time needs to be set.
FIG. 1 is a schematic diagram of the upper and lower MOSFET driving signals and the current flowing through the same bridge arm, wherein the upper tube driving signal is VGS1Indicating that the drive signal of the lower tube is VGS2Is represented by iDS1Representing the current flowing through the upper tube, iDS2Representing the current flowing through the lower tube, setting the upper and lower tubes to be in complementary conduction, and setting the dead time. During operation of the MOSFET, the direction of current flow through the MOSFET is related to the direction of load current flow, based on the current i flowing through the MOSFETDSCan be divided into three working states:
(a)iDSwhen the voltage is more than 0, the MOSFET is in a positive conducting state, and V is at the momentDS＞0；
(b)iDS0, the MOSFET is in forward blockingState, at this time VDS＞0；
(c)iDS< 0, the MOSFET is in a reverse freewheeling state, at which time VDS＜0。
The reverse freewheeling state may be MOSFET channel freewheeling, or body parasitic diode freewheeling of the MOSFET.
Although it is possible to detect iDSThe operating state of the MOSFET is judged, but the detection of the current is not convenient, and the voltage is not directly detected. According to the voltage V across the drain and source of the MOSFETDSPositive and negative and drive logic signal VGSCan also determine the operating state of the MOSFET. Wherein, VGSThe on signal of (a) is represented by "1" and the off signal is represented by "0".
(a) When V isDS> 0, drive signal VGSWhen the voltage is 1, the MOSFET is in a forward conduction state;
(b) when V isDS> 0, drive signal VGSWhen the voltage is 0, the MOSFET is in a positive blocking state;
(c) when V isDS< 0, drive signal VGSWhen the current is 1, the MOSFET is in a channel follow current state;
(d) when V isDS< 0, drive signal VGSAt "0", the MOSFET is in a body parasitic diode freewheeling state.
Thus, the voltage V of the MOSFET can be detectedDSThe working state of the MOSFET is judged according to the polarity of the voltage, and the design of the MOSFET driving circuit is realized. When the voltage V across the MOSFET is detectedDSIf < 0, the MOSFET is in a reverse conducting state, and the MOSFET opening signal is given as '1', and the MOSFET closing signal is given as '0' in other cases. And taking the OR logic relation between the given MOSFET compensation driving signal and the original MOSFET driving logic signal of the system to drive the MOSFET together. Therefore, the conduction time of the body parasitic diode of the MOSFET can be minimized, and the reverse follow current of the channel of the MOSFET replaces the follow current of the body parasitic diode, so that the conduction loss of the MOSFET is reduced, the junction temperature of the MOSFET is reduced, and the reliability of the switching tube is improved.
MOS (metal oxide semiconductor) with reduced body parasitic diode conduction timeFig. 2 shows a block diagram of a system for reducing MOSFET power loss, which includes a MOSFET101 to be driven, a differential sampling circuit 102, a voltage comparator 103, a MOSFET compensation driving signal 104, a MOSFET original driving signal 105, a logic circuit 106 for implementing an or gate, a MOSFET correction driving signal 107, and a MOSFET driving circuit 108. In a power electronic converter or system with MOSFET as switching tube, voltage signal V of MOSFET101 is collected by differential sampling circuit 102DSThe voltage comparator 103 is used to judge VDSTo derive the MOSFET compensation drive signal 104. If the voltage V across the MOSFET101 is detectedDS< 0, the MOSFET compensation drive signal 104 is given a "1", otherwise the MOSFET compensation drive signal 104 is given a "0". Taking the logic relation of the MOSFET compensation driving signal 104 and the MOSFET original driving signal 105 as an OR, the MOSFET correction driving signal 107 is obtained to drive the MOSFET101 together.
A method for reducing MOSFET power loss by reducing body parasitic diode conduction time is implemented as follows:
step 1: differential sampling circuit is utilized to collect voltage V at two ends of drain stage and source stage of MOSFETDS；
Step 2: judging V by voltage comparatorDSTo obtain a compensation driving signal of the MOSFET if the voltage V at the two ends of the MOSFET is detectedDSIf the output voltage is less than 0, the MOSFET compensation driving signal is given as '1', and otherwise, the MOSFET compensation driving signal is given as '0';
step 3: taking an OR logic relation between the MOSFET compensation driving signal and an MOSFET original driving signal of the system to obtain an MOSFET correction driving signal;
step 4: the MOSFET correction drive signal is output to the MOSFET drive circuit, and the MOSFETs are driven together.
The system and the method for reducing the power loss of the MOSFET have the following advantages that:
(1) the system and the method for reducing the power loss of the MOSFET realize the compensation of the MOSFET driving signal by detecting the voltage of the MOSFET, and in a system with a plurality of MOSFETs, particularly in a bridge circuit or a synchronous rectification circuit, the MOSFETs do not interfere with each other;
(2) according to the invention, the MOSFET channel is used for reverse follow current to replace body parasitic diode follow current, so that the power loss of the MOSFET is reduced in a mode of reducing the conduction time of the body parasitic diode, the junction temperature of the MOSFET is reduced, and the reliability of the switching tube is improved;
(3) in a bridge circuit, the system and the method provided by the invention are utilized to realize MOSFET driving signal compensation, the body parasitic diode freewheel time can be shortest and the dead time can be optimized, and the method can not change the conduction state of the original MOSFET;
(4) the system and the method for reducing the power loss of the MOSFET are suitable for various converters and systems which adopt the MOSFET as a power switch tube, and have wide application range.
The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. For those skilled in the art to which the invention pertains, several simple deductions or substitutions can be made without departing from the spirit of the invention, and all shall be considered as belonging to the protection scope of the invention.

Claims (2)

1. A system for reducing MOSFET power loss, comprising: the MOSFET driving circuit comprises a MOSFET to be driven, a differential sampling circuit, a voltage comparator, a logic circuit for realizing an OR gate and a MOSFET driving circuit, wherein the differential sampling circuit acquires a voltage signal V between a drain electrode and a source electrode of the MOSFET to be drivenDSAnd output to a voltage comparator, which determines a voltage signal VDSAnd (3) obtaining a MOSFET compensation driving signal, inputting the MOSFET compensation driving signal and the MOSFET original driving signal to a logic circuit for realizing an OR gate to obtain a MOSFET correction driving signal, inputting the MOSFET correction driving signal to a MOSFET driving circuit, and driving the MOSFET through the MOSFET driving circuit.
2. A method of reducing power loss in a MOSFET, comprising the steps of:
step 1: differential sampling circuit is used for collecting voltage signals V at two ends of drain and source of MOSFET to be drivenDSAnd applying the voltage signal VDSOutputting the voltage to a voltage comparator;
step 2: judging the voltage signal V by a voltage comparatorDSTo obtain a compensation driving signal of the MOSFET, and if a voltage signal V at two ends of the MOSFET is detectedDSIf the output signal is less than 0, the MOSFET compensation driving signal is given as '1', otherwise, the MOSFET compensation driving signal is given as '0', wherein '1' represents the MOSFET turn-on signal, and '0' represents the MOSFET turn-off signal;
step 3: inputting the MOSFET compensation driving signal and the MOSFET original driving signal of the system into a logic circuit for realizing an OR gate, and obtaining an MOSFET correction driving signal by taking the logical relation of OR by the logic circuit for realizing the OR gate;
step 4: the MOSFET correction drive signal is output to a MOSFET drive circuit, and the MOSFET is driven by the MOSFET drive circuit.
CN202111293828.7A 2021-11-03 2021-11-03 System and method for reducing power loss of MOSFET (metal-oxide-semiconductor field effect transistor) Pending CN114123737A (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6396250B1 (en) * 2000-08-31 2002-05-28 Texas Instruments Incorporated Control method to reduce body diode conduction and reverse recovery losses
US10090751B1 (en) * 2018-02-21 2018-10-02 Ixys, Llc Gate driver for switching converter having body diode power loss minimization
CN108696106A (en) * 2017-04-05 2018-10-23 富士电机株式会社 Switching element driver
CN110138367A (en) * 2019-05-16 2019-08-16 东南大学 Reduce the gate driving circuit of power device reverse recovery current
CN112204865A (en) * 2018-05-29 2021-01-08 西门子股份公司 Driving and controlling of metal oxide semiconductor field effect transistor

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6396250B1 (en) * 2000-08-31 2002-05-28 Texas Instruments Incorporated Control method to reduce body diode conduction and reverse recovery losses
CN108696106A (en) * 2017-04-05 2018-10-23 富士电机株式会社 Switching element driver
US10090751B1 (en) * 2018-02-21 2018-10-02 Ixys, Llc Gate driver for switching converter having body diode power loss minimization
CN112204865A (en) * 2018-05-29 2021-01-08 西门子股份公司 Driving and controlling of metal oxide semiconductor field effect transistor
CN110138367A (en) * 2019-05-16 2019-08-16 东南大学 Reduce the gate driving circuit of power device reverse recovery current

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