CN116260315A - Step-up-down converter with week current detection type failure protection and gallium nitride direct drive capability - Google Patents

Step-up-down converter with week current detection type failure protection and gallium nitride direct drive capability Download PDF

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Publication number
CN116260315A
CN116260315A CN202310273761.3A CN202310273761A CN116260315A CN 116260315 A CN116260315 A CN 116260315A CN 202310273761 A CN202310273761 A CN 202310273761A CN 116260315 A CN116260315 A CN 116260315A
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current detection
cycle
bridge arm
tube
gallium nitride
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杜建霞
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Hangzhou Yuanxin Semiconductor Technology Co ltd
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Hangzhou Yuanxin Semiconductor Technology Co ltd
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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
    • H02M1/0003—Details of control, feedback or regulation circuits
    • H02M1/0009—Devices or circuits for detecting current in a converter
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/10—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers
    • H02H7/12—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers
    • H02H7/1213—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers for DC-DC converters
    • 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
    • H02M1/32—Means for protecting converters other than automatic disconnection
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
    • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
    • H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
    • H02M3/157—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators with digital control
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
    • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
    • H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
    • H02M3/158—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load
    • H02M3/1582—Buck-boost converters
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Dc-Dc Converters (AREA)

Abstract

The invention discloses a buck-boost converter with cycle-by-cycle current detection type failure protection and gallium nitride direct drive capability, which comprises a driving voltage active clamping circuit, a four-tube gallium nitride buck-boost converter driving voltage intelligent power supply circuit and a cycle-by-cycle current detection type failure protection module, wherein the driving voltage is provided with a MOS transistor; four-tube gallium nitride buck-boost converter driving voltage intelligent power supply circuit; and the week current detection type failure protection module is used for placing current detection resistors on the input side and the output side, realizing cycle-by-cycle high-precision current detection on the buck side bridge arm and the boost side bridge arm, and switching off all switching tubes instantly when short circuit occurs. The beneficial effects of the invention are as follows: in three aspects of gallium nitride direct driving technology, driving power supply technology, current detection failure protection technology and the like, innovative design and control methods are provided, and more stable and reliable driving, power supply and protection functions are realized, so that the reliability and the system stability of the gallium nitride buck-boost converter can be effectively improved.

Description

Step-up-down converter with week current detection type failure protection and gallium nitride direct drive capability
Technical Field
The invention relates to a high-reliability buck-boost power converter based on third-generation semiconductor gallium nitride, which mainly comprises a cycle-by-cycle current detection type failure protection and gallium nitride direct-drive capacity.
Background
In recent years, a third generation wide bandgap semiconductor material typified by gallium nitride has been attracting attention because of its characteristics such as high breakdown field, high saturated electron velocity, high thermal conductivity, high electron density, high mobility, and high power tolerance. Gallium nitride devices, due to their special physical structure, are excellent in all respects in performance as conventional silicon devices. Gallium nitride switching power devices are being used as core power devices of third-generation semiconductors, gradually replace traditional silicon devices, and are applied to the fields of electric automobiles, big data centers, high-end consumer electronics, industrial medical treatment and the like. The gallium nitride switching device can improve the electric energy conversion efficiency of the system, improve the switching frequency of the system, reduce the size and the volume of passive devices such as capacitors, inductors and the like in the system, realize energy conservation and carbon reduction, and greatly reduce the cost of the system.
However, due to the physical structure specificity of gallium nitride devices, it will face a series of challenges in terms of direct drive (direct drive), buck-boost converter systems, and device failure protection.
Firstly, in the aspect of gallium nitride driving, as a P-type gallium nitride grid structure is adopted, the gallium nitride switching device has the characteristics of low grid withstand voltage and easy damage of overvoltage driving. In the conventional step-up, step-down, and step-up-and-down converters, the driving supply voltage Vcc is 5V, and when the conventional voltage bootstrap driving circuit drives a voltage arm upper tube, a switching network composed of a diode D and a capacitor C is required to store electric energy to provide energy for upper tube driving, as shown in fig. 1. However, since the gallium nitride switching device has no reverse diode, the switching node voltage will drop to-3V at the non-overlapping dead time, which will result in the bootstrap capacitor C being charged to 7V-8V. When the upper tube is turned on, the gate of the upper tube of gallium nitride is driven to a maximum of 8V, which is higher than the gate breakdown voltage of 6V-7V, resulting in damage to the gallium nitride device. On the other hand, the voltage drop of the bootstrap diode is too large, so that the difference of the driving voltage values of the upper tube and the lower tube is large, the driving delay between the upper tube and the lower tube is different, and the reliability is reduced.
Secondly, for a four-tube gallium nitride Buck-Boost (Buck-Boost) converter, the four-tube gallium nitride Buck-Boost converter has two bridge arms for Buck and Boost simultaneously, so that great challenges are brought to gallium nitride driving and device failure protection. The driving and failure protection problems of the four-tube gallium nitride buck-boost converter are solved, which is equivalent to the driving and failure protection problems of the gallium nitride buck-boost converter and the gallium nitride buck-boost converter, so the following description takes the gallium nitride buck-boost converter as an example. In the aspect of a four-tube gallium nitride bidirectional Buck-Boost driving circuit, a conventional driving circuit needs to provide a charging path for bootstrap capacitors driven by upper tubes of two bridge arms, so that a lower tube needs to have a certain conduction time in each switching cycle, as shown in fig. 2. Because in the step-up or step-down mode of the four-tube-gallium nitride step-up/down converter in operation, there is a bootstrap capacitor charging path which is shown in fig. 2 and cannot be realized in a state that one of the upper tube and the lower tube of the four-tube-gallium nitride step-up/step-down converter are normally on, the problem that the constant tube is kept powered to counteract the gate leakage of the gallium nitride transistor is urgent to be solved. The failure to realize the normally-on working state of the upper pipe of the bridge arm introduces additional switching loss, thereby reducing the electric energy conversion efficiency and the stability of the system. In addition, if the gallium nitride switching device in the buck-boost converter fails to cause short circuit between the drain electrode and the source electrode of the device, the other switching tube of the bridge arm is in direct short circuit when being opened. The current detection is carried out on the buck side bridge arm (VIN side) and the boost side bridge arm (VOUT side) one by one, and when a short circuit occurs, one undamaged switching tube is turned off instantaneously, so that the short circuit of any bridge arm is avoided, and the reliability and the safety of the system are improved.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide the buck-boost converter with the week current detection type failure protection and gallium nitride direct drive capability, so that the reliability and the system safety of the gallium nitride buck-boost converter are improved.
The aim of the invention is achieved by the following technical scheme. A buck-boost converter with week current detection type failure protection and gallium nitride direct drive capability comprises a driving voltage active clamping circuit, a four-tube gallium nitride buck-boost converter driving voltage intelligent power supply circuit and a week current detection type failure protection module,
the driving voltage active clamp circuit adopts back-to-back MOS transistors, the on time of the MOS transistors is bidirectionally controllable, and the bootstrap capacitor is charged only when the lower tube of the bridge arm is on and in a specific undervoltage or starting working mode;
the four-tube gallium nitride buck-boost converter driving voltage intelligent power supply circuit detects voltages at two ends of a bootstrap capacitor of a normally-on upper tube in real time, and when the voltages are lower than a bottom threshold voltage V L When the voltage is charged back to the top threshold voltage V, the bootstrap capacitor of the other bridge arm is charged from the bootstrap capacitor of the other bridge arm or the high-end voltage of the other bridge arm H When the charging channel is closed;
the cycle-by-cycle current detection type failure protection module is characterized in that a current detection resistor is arranged at the input side and the output side, or an integrated FET or a metal resistor Sensing circuit is introduced into the lower tube of the bridge arm, so that high-precision current detection of the bridge arm at the buck side and the bridge arm at the boost side in a cycle-by-cycle manner is realized, and all switching tubes are turned off instantaneously when short circuit occurs.
Furthermore, the driving voltage active clamping circuit adopts a mode that a PMOS BP tube and an NMOS BN tube are connected in series and the switch of the PMOS BP tube and the NMOS BN tube is controlled by an auxiliary logic circuit; when the lower tube ML is on, the driving voltage GN is high level Vcc, and the inverter INV generates low level to drive the PMOS tube BP to be on, so that Vcc potential is generated at the source S of the NMOS tube BN; meanwhile, C2 stores Vcc voltage when GN is at a low level, and when GN is at a high level Vcc, a potential twice Vcc is generated at the gate G of the NMOS tube BN, so that the gate-source voltage difference VGS of the NMOS tube BN is Vcc, thereby opening the BN tube; when BP and BN are simultaneously turned on, the conduction voltage drop is extremely small, VCC charges the bootstrap capacitor C1, and the charging process only occurs at the moment of turning on the ML, so that the charging voltage of the bootstrap capacitor C1 is almost equal to the driving voltage Vcc.
Furthermore, the driving voltage active clamping circuit adopts a driving voltage checking protection mechanism of undervoltage UVLO and overvoltage OVLO in a driving voltage domain, self-adaptive bootstrap capacitor charging is realized during undervoltage UVLO, and efficient lossless active voltage clamping is performed on the driving voltage domain during OVLO.
Furthermore, the week Current detection type failure protection module is characterized in that a Current detection resistor R1 is arranged at the input side, the Current detection resistor R1 is connected with a failure protection module FMEA1 through a Current Sensor1 of the Current detection module, AND output signals of the FMEA1 are respectively connected with gate driving signals TGINA AND TGINB through AND gates AND1 AND AND2 to control an upper pipe A AND a lower pipe B of a left bridge arm; under normal conditions, the FMEA1 failure protection module outputs high level, and the driving voltages of the upper pipe and the lower pipe are respectively determined by driving signals TGINA and TGINB; when the pipe A or the pipe B is short-circuited, the bridge arm enters a straight-through state and can be detected by the current detection resistor R1 in one switching period, the low level is output after the judgment of the failure protection module FMEA1, driving signals TGINA and TGINB are blocked, and the switch is closed to cut off the upper pipe A and the lower pipe B, so that the protection of the bridge arm is realized.
Furthermore, the week Current detection type failure protection module is provided with a Current detection resistor R2 at the output side, the Current detection resistor R2 is connected with a failure protection module FMEA2 through a Current Sensor2 of the Current detection module, AND output signals of the FMEA2 are respectively connected with gate driving signals TGIND AND TGINC through AND gates AND3 AND AND4, AND then the upper pipe D AND the lower pipe C of the right bridge arm are controlled; under normal conditions, the failure protection module FMEA2 outputs high level, and the driving voltages of the upper tube D and the lower tube C are respectively determined by driving signals TGIND and TGINC; when the D pipe or the C pipe is short-circuited, the bridge arm enters a straight-through state and can be detected by the current detection resistor R2 in one switching period, a low level is output after the judgment of the failure protection module FMEA2, driving signals TGIND and TGINC are blocked, and the switch is closed to cut off the upper pipe D and the lower pipe C, so that the protection of the bridge arm is realized.
Furthermore, the week current detection type failure protection module integrates FET Sensing or an integrated built-in polysilicon/metal resistor RES Sensing circuit in the lower tube of each bridge arm, and realizes FMEA failure protection under the condition of week current detection or overcurrent by detecting the voltage drop of the FET Sensing or the integrated built-in polysilicon/metal resistor RES Sensing circuit as conducting current information.
Furthermore, the cycle-by-cycle current detection type failure protection module realizes accurate control of a current loop of the buck-boost converter by taking a sampling result of the current detection of the sampling resistor at the input side and the output side or the current detection of the integrated FET/metal resistor of the lower pipe of the bridge arm as a feedback input.
The beneficial effects of the invention are as follows: the invention mainly aims at the problem of reliability of a lifting power converter based on a third-generation semiconductor gallium nitride device, and provides innovative design and control methods in three aspects of gallium nitride direct driving technology, driving power supply technology, current detection failure protection (FMEA) technology, and the like, thereby realizing more stable and reliable driving, power supply and protection functions, and further effectively improving the reliability and system stability of the gallium nitride lifting power converter.
1. A drive voltage active clamp circuit is employed that replaces the diode portion of a conventional bootstrap circuit with back-to-back MOS transistors. On the one hand, the voltage drop of the back-to-back MOS transistors in the on state is extremely low, so that the consistent driving voltages of the upper and lower transistors can be realized. On the other hand, the on time of the MOS transistor is bidirectionally controllable, and the bootstrap capacitor is charged only when the bridge arm lower tube is on and in a specific undervoltage or starting working mode. Because the voltage of the switch node is close to 0V when the lower tube is conducted, the condition that the bootstrap capacitor is overcharged does not exist, and therefore active clamping of driving voltage is achieved. In addition, the invention provides a protection mechanism for undervoltage UVLO and overvoltage OVLO of the driving voltage domain in driving voltage inspection, self-adaptive bootstrap capacitor charging can be realized in undervoltage UVLO, and efficient and lossless active voltage clamping is performed on the driving voltage domain in OVLO, so that the stability and safety of the system are further improved.
2. By adopting a four-tube gallium nitride buck-boost converter driving voltage intelligent power supply circuit, the voltage at two ends of a bootstrap capacitor of a normally-on upper tube is detected in real time, and when the voltage is lower than a certain voltage V L When the voltage is charged back to V, the bootstrap capacitor of the other bridge arm is charged from the bootstrap capacitor of the other bridge arm or the high-end voltage of the other bridge arm H At this time, the charging path is turned off. Through the hysteresis and self-adaptive control method, the voltage stability of the bootstrap capacitor of the normal-pass pipe is realized and the gallium nitride grid is counteractedThe effect of the leakage current.
3. In order to solve the problem that a gallium nitride switching device in a four-tube Buck-Boost (Buck-Boost) converter fails to cause short circuit of a drain electrode and a source electrode of the device, the invention provides a method for placing a current detection resistor at an input side and an output side or introducing an integrated FET or a metal resistor Sensing circuit into a lower tube of a bridge arm to realize cycle-by-cycle high-precision current detection of the bridge arm at the Buck side and the bridge arm at the Boost side, and switching off all switching tubes instantly when short circuit occurs, so that further system damage caused by short circuit of any bridge arm is avoided, and the reliability and safety of a system are improved. Because the on-chip integrated FET or metal resistor is easy to realize higher current precision detection, compared with the off-chip sampling resistor, the required sampling resistor value can be greatly reduced, thereby realizing smaller system volume and higher efficiency. Meanwhile, through the current detection of the sampling resistor at the input side and the output side or the current detection of the integrated FET/metal resistor of the lower pipe of the bridge arm, the sampling result can also be used as feedback input to realize the accurate control of the current loop of the buck-boost converter, and the dynamic performance of the system is improved.
Drawings
FIG. 1 is a conventional bootstrap driving circuit;
FIG. 2 is a schematic diagram of a conventional four-tube GaN buck-boost converter;
FIG. 3 is a schematic diagram of a driving voltage active clamp circuit according to the present invention;
FIG. 4 is a schematic diagram of a driving supply voltage protection scheme according to the present invention;
FIG. 5 is a schematic diagram of a four-tube GaN buck-boost converter drive voltage intelligent power supply circuit according to the present invention;
FIG. 6 is a bootstrap capacitor charging flow chart of the buck leg of the present invention;
FIG. 7 is a bootstrap capacitor charging flow chart of the boost leg of the present invention;
FIG. 8 is a cycle-by-cycle current sensing type fail safe module of the present invention;
FIG. 9 is a cycle-by-cycle current sense type fail-safe module based on integrated FET Sensing in accordance with the present invention;
fig. 10 is a schematic diagram of a week current sensing type fail safe module based on integrated metal resistance according to the present invention.
Detailed Description
The invention will now be described in detail with reference to the accompanying drawings and examples:
the invention provides a buck-boost converter with a week current detection type failure protection and gallium nitride direct drive capability, which comprises a driving voltage active clamping circuit, a four-tube gallium nitride buck-boost converter driving voltage intelligent power supply circuit and a week current detection type failure protection module.
1. Active clamp driving circuit for upper tube of bridge arm in gallium nitride bridge circuit
As shown in fig. 3, in the conventional driving circuit, the driving voltage Vcc to the positive electrode BST of the bootstrap capacitor C1 is implemented by a diode, which will cause the problem of unbalanced driving voltages of the upper and lower tubes. In the proposed driving circuit, the conventional diode is replaced by adopting a mode that a PMOS BP tube and an NMOS BN tube are connected in series and the switch of the PMOS BP tube and the NMOS BN tube is controlled by an auxiliary logic circuit.
When the lower tube ML is turned on, the driving voltage GN is high level Vcc, and the inverter INV generates low level to drive the PMOS tube BP to be turned on, so that Vcc potential is generated at the source S of the NMOS tube BN. Meanwhile, since the Vcc voltage is stored when GN is low, and when GN is high, a potential twice Vcc can be generated at the gate G of the NMOS transistor BN, so that the gate-source voltage difference VGS of the NMOS transistor BN can be Vcc, thereby turning on the BN transistor. When BP and BN are simultaneously on, the on voltage drop is extremely small, VCC can charge the bootstrap capacitor C1, and the charging process only occurs at the moment of turning on the ML, so that the charging voltage of the bootstrap capacitor C1 is almost equal to the driving voltage Vcc.
Therefore, the driving circuit not only can solve the problem of unbalanced driving voltage generated by the diode in the traditional bootstrap circuit, but also can avoid the problem of driving overvoltage caused by charging the bootstrap capacitor in the follow current period of the lower tube, thereby greatly improving the reliability of the gallium nitride driving circuit.
In addition, the invention also adds overvoltage and undervoltage detection and protection functions of the driving voltage in the driving circuit. Conventional drive circuit designs are primarily directed to silicon or silicon carbide devices having gates with high withstand voltages (typically 20V or more) and typically require drive levels of 15V or less. Thus, the device gate is not easily damaged, although there may be some voltage fluctuations in the drive supply voltage. And different requirements are imposed on gallium nitride drives. Since the gan gate voltage is low (e.g., 6V is common), the drive level is relatively close to the gate voltage (e.g., 5V) in order to achieve the smallest possible on-resistance, so the drive supply voltage is more sensitive to transient voltage fluctuations. In order to meet the requirement that the gallium nitride grid electrode cannot be broken down to cause system breakdown under the condition that the driving power supply voltage fluctuates severely, the invention provides a driving voltage protection strategy added in the gallium nitride driving. As shown in fig. 3, the Sensor/Clamp module is responsible for detecting the voltage at two ends of the supply capacitor C1, charging the bootstrap capacitor at Under Voltage (UVLO), performing voltage clamping protection at Over Voltage (OVLO), and simultaneously automatically turning off the corresponding device MH to generate a protection signal, thereby realizing protection of the system. The protection functions of the driving circuits UVLO and OVLO are shown in a flow chart 4, wherein Vov is an overvoltage threshold value, and Vuv is an undervoltage threshold value.
2. Provides a four-tube gallium nitride buck-boost converter driving voltage intelligent power supply circuit
The invention provides a four-tube Buck-Boost bidirectional DC-DC direct drive power supply circuit. In order to increase the boosting or step-down efficiency, the driving circuit needs to be able to realize the following four operating states:
(1) When the forward power circulation boosting works, the switching tube A is normally open, and the switching tube B is normally closed;
(2) When the forward power circulation is in voltage reduction operation, the switching tube D is normally open, and the switching tube C is normally closed;
(3) When the reverse power circulation boosting works, the switching tube D is normally open, and the switching tube C is normally closed;
(4) When the reverse power circulation is in voltage reduction operation, the switching tube A is normally open, and the switching tube B is normally closed.
The traditional bootstrap driving circuit can charge the bootstrap capacitor only when the lower tube is opened, and the normally open state of the upper tube cannot be realized L When the bootstrap capacitor or the other bridge arm is startedThe high-end voltage of the other bridge arm charges the bootstrap capacitor of the bridge arm, when the voltage is charged back to the top threshold voltage V H At this time, the charging path is turned off.
2.1 working conditions (1) and (4) -normal on of the switching tube A and normal off of the switching tube B are realized.
As shown in fig. 5, the left leg is composed of an upper pipe a and a lower pipe B. The driving voltage of the upper tube is supplied by a capacitor C1. The voltage detection unit sensor is arranged on the C1, and the on and off of the charging switches S1 and S3 are controlled by detecting the driving voltage range and the working state of the circuit. The charging input of the bootstrap capacitor C1 is composed of a traditional charging path composed of VCC and S3 and a high-voltage charging path composed of VOUT, BST2, LDO/Charge Pump module and S1. In the working conditions (1) and (4), the conventional charging path cannot meet the requirements because the upper pipe A is required to be normally on, so that the switch S3 is disconnected. Only the bootstrap capacitor needs to be charged by the control S1.
The high-voltage charging input path is formed by connecting a right bridge arm output Vout and a right bridge arm upper tube driving high-voltage side BST2 through a diode to realize an automatic high-voltage selection function. And the C1 is charged by connecting with a charging switch S1 through an LDO or Charge Pump voltage conversion module. If the upper tube A of the left bridge arm is normally on, the charging voltage of S1 needs to be higher than VIN+VCC. Because the conditions VOUT > VIN are satisfied in the working conditions (1) and (4), and the potential of the BST2 point can be raised to VOUT+Vcc at the highest, the charging switch S1 is turned on to charge C1 by using BST2, the voltage of the charging switch S1 is kept in a required driving potential range, and the leakage current required to be consumed by the grid electrode in normally on is compensated, so that the upper tube A is in a normally on state.
The logic of the charge control switch S1 is shown in fig. 6. Where VH is the top threshold voltage of the drive voltage and VL is the bottom threshold voltage of the drive voltage.
2.2-working conditions (2) and (3) -normally open of the switching tube D and normally closed of C
Similar to the driving mode of the working conditions (1) and (4), in the working conditions (2) and (3), the upper pipe D of the right bridge arm is required to be normally closed by the lower pipe C. At this time, the switch S4 of the conventional driving charging path is turned off, and the driving capacitor C2 is charged through the high voltage charging path composed of VIN, BST1, LDO/Charge Pump module, S2.
If the upper tube D of the right bridge arm is normally on, the charging voltage S2 needs to be higher than vout+vcc, and the conditions Vout < VIN are satisfied under the working conditions (2) and (3), and because the potential of the point BST1 can rise to vin+vcc when the upper tube of the left bridge arm is on, the charging switch S2 is turned on, and the charging switch S2 can effectively charge the C2 by using BST1, so that the voltage of the charging switch S2 is kept at the required driving potential, thereby realizing the normal on of the switching tube D. The control logic of the S2 charge switch is shown in fig. 7.
3. Provides a cycle-by-cycle current detection type FMEA (Failure Mode and Effect Analysis) failure protection core control technology
The traditional four-tube bidirectional DC-DC design generally detects the midpoint of the two bridge arms of the buck-boost and an external sampling resistor connected in series with the inductor for overcurrent protection, as shown in fig. 2. When the protection is short-circuited or direct current passes through the buck bridge arm or the boost bridge arm, the through current does not pass through the sampling resistor, so that the switching tube cannot be effectively protected.
Aiming at bridge arm through phenomenon caused by failure or short circuit of a gallium nitride switching device in a four-tube Buck-Boost (Buck-Boost) converter, the invention provides two effective current detection methods:
(1) And the current detection resistors are arranged on the input side and the output side, the current detection is carried out on the buck side bridge arm and the boost side bridge arm cycle by cycle, overcurrent protection and turn-off are realized by matching with the core switch control, the failure protection of the FMEA (failure mode detection) is realized by cycle-by-cycle current detection, and the requirements of automobile electronics on high stability and high reliability are met, as shown in figure 8. A Current detection resistor R1 is placed on the input side and is connected to the failure protection module FMEA1 through a Current Sensor 1. The FMEA1 output signal is coupled to gate drive signals TGINA, TGINB via AND gates AND1 AND2, respectively, to control left side leg upper tube a AND lower tube B. Under normal conditions, the FMEA1 fail safe module outputs a high level, and the upper and lower tube driving voltages are determined by driving signals TGINA, TGINB, respectively. When the A pipe or the B pipe is short-circuited, the bridge arm enters a straight-through state and is detected by the sampling resistor R1 in one switching period. And outputting low level after judging by the failure protection module FMEA1, blocking driving signals TGINA and TGINB, closing a switch to turn off an upper pipe A and a lower pipe B, and protecting a bridge arm. Similarly, a Current detection resistor R2 is arranged on the output side, the Current detection resistor R2 is connected with a failure protection module FMEA2 through a Current detection module Current Sensor2, the Current detection module Current Sensor2 is used for detecting the Current of VOUT, AND FMEA2 output signals are respectively connected with gate drive signals TGIND AND TGINC through AND gates AND3 AND AND4, AND then the upper pipe D AND the lower pipe C of the right bridge arm are controlled; under normal conditions, the failure protection module FMEA2 outputs high level, and the driving voltages of the upper tube D and the lower tube C are respectively determined by driving signals TGIND and TGINC; when the D pipe or the C pipe is short-circuited, the bridge arm enters a straight-through state and can be detected by the current detection resistor R2 in one switching period, a low level is output after the judgment of the failure protection module FMEA2, driving signals TGIND and TGINC are blocked, and the switch is closed to cut off the upper pipe D and the lower pipe C, so that the protection of the bridge arm is realized.
(2) The other current detection and failure protection method provided by the invention is that an FET Sensing circuit or an integrated built-in polysilicon/metal resistor RES Sensing circuit is integrated in the lower tube of each bridge arm, and the FMEA failure protection under the condition of cycle-by-cycle current detection or overcurrent is realized by detecting the voltage drop of the FET Sensing circuit as on-current information, as shown in fig. 9 and 10.
When the lower tube-B conducts current, the OPAMP read current flows through the voltage drop of the FET Sensing or On Chip Resistor Sensing module, the output is sent to the FMEA failure protection module for logic judgment, and the AND gate logic is used for controlling the driving voltage of the upper tube and the lower tube, so that the cycle-by-cycle current detection and failure protection inside the chip are realized.
When the bridge arm A tube of the step-down bridge arm fails or is short-circuited due to some external reasons, at the moment of opening the B tube, through ET Sensing or On Chip Resistor Sensing, the system detects an overcurrent signal and triggers an FMEA protection mechanism, and simultaneously, the bridge arm A tube and the bridge arm B tube are turned off and intermittently restarted for detection until the short-circuited phenomenon of the A tube is relieved, so that the system is recovered. Similarly, effective FMEA failsafe can be achieved for switching tubes C and D of the boost leg by the same cycle-by-cycle current detection. The detection method can effectively and rapidly protect all switching tubes and converter systems in the four-tube buck-boost converter from over-temperature ignition, thereby improving the reliability of the gallium nitride bidirectional DC-DC converter.
It should be understood that equivalents and modifications to the technical scheme and the inventive concept of the present invention should fall within the scope of the claims appended hereto.

Claims (7)

1. The utility model provides a have step-up-down voltage converter of week electric current detection formula fail safe and gallium nitride ability of directly driving which characterized in that: comprises a driving voltage active clamping circuit, a four-tube gallium nitride buck-boost converter driving voltage intelligent power supply circuit and a cycle-by-cycle current detection type failure protection module, wherein,
the driving voltage active clamp circuit adopts back-to-back MOS transistors, the on time of the MOS transistors is bidirectionally controllable, and the bootstrap capacitor is charged only when the lower tube of the bridge arm is on and in a specific undervoltage or starting working mode;
the four-tube gallium nitride buck-boost converter driving voltage intelligent power supply circuit detects voltages at two ends of a bootstrap capacitor of a normally-on upper tube in real time, and when the voltages are lower than a bottom threshold voltage V L When the voltage is charged back to the top threshold voltage V, the bootstrap capacitor of the other bridge arm is charged from the bootstrap capacitor of the other bridge arm or the high-end voltage of the other bridge arm H When the charging channel is closed;
the cycle-by-cycle current detection type failure protection module is characterized in that a current detection resistor is arranged at the input side and the output side, or an integrated FET or a metal resistor Sensing circuit is introduced into the lower tube of the bridge arm, so that high-precision current detection of the bridge arm at the buck side and the bridge arm at the boost side in a cycle-by-cycle manner is realized, and all switching tubes are turned off instantaneously when short circuit occurs.
2. The buck-boost converter with cycle-by-cycle current detection type fail-safe and gallium nitride direct drive capability of claim 1, wherein: the driving voltage active clamp circuit adopts a mode that a PMOS BP tube and an NMOS BN tube are connected in series and the switch of the driving voltage active clamp circuit is controlled by an auxiliary logic circuit; when the lower tube ML is on, the driving voltage GN is high level Vcc, and the inverter INV generates low level to drive the PMOS tube BP to be on, so that Vcc potential is generated at the source S of the NMOS tube BN; meanwhile, C2 stores Vcc voltage when GN is at a low level, and when GN is at a high level Vcc, a potential twice Vcc is generated at the gate G of the NMOS tube BN, so that the gate-source voltage difference VGS of the NMOS tube BN is Vcc, thereby opening the BN tube; when BP and BN are simultaneously turned on, the conduction voltage drop is extremely small, VCC charges the bootstrap capacitor C1, and the charging process only occurs at the moment of turning on the ML, so that the charging voltage of the bootstrap capacitor C1 is almost equal to the driving voltage Vcc.
3. The buck-boost converter with cycle-by-cycle current sensing failsafe and gallium nitride direct drive capability of claim 1 or2, wherein: the driving voltage active clamping circuit adopts a driving voltage checking protection mechanism of undervoltage UVLO and overvoltage OVLO in a driving voltage domain, self-adaptive bootstrap capacitor charging is realized under the undervoltage UVLO, and efficient and lossless active voltage clamping is carried out on the driving voltage domain during the OVLO.
4. The buck-boost converter with cycle-by-cycle current detection type fail-safe and gallium nitride direct drive capability of claim 1, wherein: the week Current detection type failure protection module is characterized in that a Current detection resistor R1 is arranged on an input side AND is connected with a failure protection module FMEA1 through a Current Sensor1 of the Current detection module, AND an FMEA1 output signal is respectively connected with gate driving signals TGINA AND TGINB through AND gates AND1 AND AND2 to control a left bridge arm upper pipe A AND a left bridge arm lower pipe B; under normal conditions, the failure protection module FMEA1 outputs a high level, and the driving voltages of the upper pipe A and the lower pipe B are respectively determined by driving signals TGINA and TGINB; when the pipe A or the pipe B is short-circuited, the bridge arm enters a straight-through state and can be detected by the current detection resistor R1 in one switching period, the low level is output after the judgment of the failure protection module FMEA1, driving signals TGINA and TGINB are blocked, and the switch is closed to cut off the upper pipe A and the lower pipe B, so that the protection of the bridge arm is realized.
5. The buck-boost converter with cycle-by-cycle current detection failsafe and gallium nitride direct drive capability of claim 4, wherein: the week-by-week Current detection type failure protection module is characterized in that a Current detection resistor R2 is arranged on an output side AND is connected with a failure protection module FMEA2 through a Current Sensor2 of the Current detection module, AND an FMEA2 output signal is respectively connected with gate driving signals TGIND AND TGINC through AND gates AND3 AND AND4 to control a right bridge arm upper pipe D AND a right bridge arm lower pipe C; under normal conditions, the failure protection module FMEA2 outputs high level, and the driving voltages of the upper tube D and the lower tube C are respectively determined by driving signals TGIND and TGINC; when the D pipe or the C pipe is short-circuited, the bridge arm enters a straight-through state and can be detected by the current detection resistor R2 in one switching period, a low level is output after the judgment of the failure protection module FMEA2, driving signals TGIND and TGINC are blocked, and the switch is closed to cut off the upper pipe D and the lower pipe C, so that the protection of the bridge arm is realized.
6. The buck-boost converter with cycle-by-cycle current detection type fail-safe and gallium nitride direct drive capability of claim 1, wherein: and the week-by-week current detection type failure protection module integrates an FET Sensing circuit or an integrated built-in polysilicon/metal resistor RES Sensing circuit in the lower tube of each bridge arm, and realizes FMEA failure protection under the condition of week-by-week current detection or overcurrent by detecting the voltage drop of the FET Sensing circuit as conducting current information.
7. The buck-boost converter with cycle-by-cycle current sensing failsafe and gallium nitride direct drive capability of claim 1 or 4 or 5 or 6, wherein: the cycle-by-cycle current detection type failure protection module realizes accurate control of a current loop of the buck-boost converter by taking a sampling result of current detection of sampling resistors at an input side and an output side or current detection of an integrated FET/metal resistor of a lower pipe of a bridge arm as a feedback input.
CN202310273761.3A 2023-03-21 2023-03-21 Step-up-down converter with week current detection type failure protection and gallium nitride direct drive capability Pending CN116260315A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117543951A (en) * 2023-11-15 2024-02-09 上海水木蓝鲸半导体技术有限公司 Buck-boost circuit, short circuit detection method and converter
CN118074521A (en) * 2024-02-22 2024-05-24 上海帝迪集成电路设计有限公司 Bootstrap circuit suitable for four-tube buck-boost converter and bootstrap method thereof

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117543951A (en) * 2023-11-15 2024-02-09 上海水木蓝鲸半导体技术有限公司 Buck-boost circuit, short circuit detection method and converter
CN118074521A (en) * 2024-02-22 2024-05-24 上海帝迪集成电路设计有限公司 Bootstrap circuit suitable for four-tube buck-boost converter and bootstrap method thereof
CN118074521B (en) * 2024-02-22 2024-08-09 上海帝迪集成电路设计有限公司 Bootstrap circuit suitable for four-tube buck-boost converter and bootstrap method thereof

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