WO2022170954A1 - Dc/dc变换器的控制器及其控制系统 - Google Patents

Dc/dc变换器的控制器及其控制系统 Download PDF

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Publication number
WO2022170954A1
WO2022170954A1 PCT/CN2022/073547 CN2022073547W WO2022170954A1 WO 2022170954 A1 WO2022170954 A1 WO 2022170954A1 CN 2022073547 W CN2022073547 W CN 2022073547W WO 2022170954 A1 WO2022170954 A1 WO 2022170954A1
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WIPO (PCT)
Prior art keywords
converter
switch tube
switch
voltage
controller
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Application number
PCT/CN2022/073547
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English (en)
French (fr)
Inventor
王磊
伍梁
杨滚
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华为数字能源技术有限公司
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Publication of WO2022170954A1 publication Critical patent/WO2022170954A1/zh

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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
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
    • H02M3/33576—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
    • 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
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
    • H02M3/33571—Half-bridge at primary side of an isolation transformer
    • 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
    • H02M1/0048—Circuits or arrangements for reducing losses
    • H02M1/0054—Transistor switching losses
    • 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
    • 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
    • H02M1/322—Means for rapidly discharging a capacitor of the converter for protecting electrical components or for preventing electrical shock
    • 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
    • H02M3/01—Resonant 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
    • H02M1/0064—Magnetic structures combining different functions, e.g. storage, filtering or transformation
    • 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

Definitions

  • the present application relates to the technical field of power supplies, in particular to a controller of a DC/DC converter and a control system thereof.
  • the DC/DC converter includes switch tubes, inductors and capacitors, etc. By controlling the on-off of the switch tubes to charge and discharge the inductors and capacitors, thereby converting the input DC voltage into a set value DC voltage. However, there is switching loss in the on-off process of the switch tube.
  • FIG. 1 is a schematic diagram of voltage and current during the switching process of the switch tube provided by the embodiment of the present application. As shown in Figure 1, in the process of turning on the switch, there is an overlap between the current rise of the switch and the drop of the voltage of the switch, resulting in a turn-on loss. The turn-on loss can be understood as the power generated by the switch from off to on. loss. In the same way, in the process of switching off the switch, there is also an overlap between the current drop of the switch and the rise of the voltage of the switch, and the turn-off loss is generated. Power loss.
  • the embodiments of the present application provide a controller of a DC/DC converter and a control system thereof, which can reduce losses in the DC/DC converter.
  • an embodiment of the present application provides a controller of a DC/DC converter, wherein the controller is coupled to the above-mentioned DC/DC converter, and the DC/DC converter includes a first switch tube and a second switch tube , a first capacitor and a transformer, the transformer includes an excitation inductance and a transformer leakage inductance; the first switch tube and the second switch tube are connected in series and then coupled to both ends of the DC power supply, and the primary side of the transformer is connected in parallel through the first capacitor Both ends of the first switch tube and the secondary side of the transformer are coupled with a DC load, wherein,
  • the controller controls the first switch tube to be turned on, so that the first capacitor passes through the first switch tube, the excitation inductance and the transformer leakage inductance form a first closed loop, and the current of the excitation inductance increases along the first direction ;
  • the controller controls the first switch tube to be turned off after a preset time period, so as to reduce the voltage across the second switch tube;
  • the controller controls the second switch to turn on when the voltage across the second switch is the first preset voltage threshold, so that the DC power supply passes through the second switch, the first capacitor, and the transformer
  • the leakage inductance and the excitation inductance form a second closed loop.
  • the DC/DC converter enters the first state, and the current of the excitation inductance increases along a second direction, wherein the second direction is opposite to the first direction.
  • the first switch tube before the DC/DC converter enters the first state, the first switch tube is controlled to be turned on to provide a current in the negative direction to the second switch tube, and the voltage across the second switch tube is reduced to the first state.
  • the voltage threshold By presetting the voltage threshold, implementing the embodiments of the present application can reduce the turn-on loss of the DC/DC converter.
  • the controller sends at least one signal to the first switch tube and the second switch tube according to a preset cycle, respectively. Two pulse waves, so that the above-mentioned DC/DC converter provides the target power to the above-mentioned DC load.
  • the controller sends at least two pulse waves to the first switch tube and the second switch tube respectively according to a preset period, so that the DC/DC converter can greatly improve the performance of the DC/DC converter on the basis of reducing the turn-on loss. energy efficiency.
  • the controller when the second switch is switched from the first state to the second state, of the DC/DC converter After the tube is turned off, the first switch tube is controlled to be turned on. At this time, the first capacitor, the leakage inductance of the transformer, the excitation inductance and the first switch tube form a third closed loop, and the current of the excitation inductance is along the second direction. reduce;
  • the controller controls the first switch to turn off when the current of the excitation inductor decreases to a first preset current threshold.
  • the control of the first switch tube is increased by increasing the control of the first switch tube after the DC/DC converter is switched from the first state to the second state and after the second switch tube is turned off. It is turned on, the energy stored in the leakage inductance of the transformer can be transferred to the DC load, thereby improving the energy utilization rate; and the first switch tube is turned off when the current of the excitation inductance decreases to the first preset current threshold, which can reduce the first switch.
  • the voltage at both ends of the switch tube oscillates, reducing the electromagnetic interference of the DC/DC converter.
  • the above-mentioned second state is that both the above-mentioned first switch tube and the above-mentioned second switch tube are in an off state, and the above-mentioned first switch tube is in an off state.
  • the parasitic capacitance and the parasitic capacitance of the second switch tube, the first capacitance, the excitation inductance and the leakage inductance of the transformer form a resonance circuit.
  • the controller controls the first switch to be turned on, the parasitic capacitance of the first switch and the above
  • the parasitic capacitance of the second switch tube forms a resonance circuit with the first capacitor, the excitation inductance and the leakage inductance of the transformer, and the voltage across the first switch tube is an oscillating voltage;
  • the controller When receiving the signal that the DC/DC converter enters the first state, the controller obtains the voltage across the first switch tube;
  • the controller controls the first switch transistor to turn on when the oscillation voltage across the first switch transistor is a second preset voltage threshold.
  • the oscillating voltage includes various periodic voltages
  • the second preset voltage threshold is a minimum voltage value in any periodic voltage.
  • the signal that the above-mentioned DC/DC converter enters the above-mentioned first state is determined according to the output voltage of the above-mentioned DC/DC converter.
  • the voltage across the second switch tube is reduced to the first preset voltage threshold after a first period of time;
  • the current of the excitation inductance decreases from the target current to the second preset current threshold after the first time period, and the target current is obtained by increasing the current of the excitation inductance after the preset time period.
  • the above-mentioned first preset voltage threshold is zero.
  • the above-mentioned first preset current threshold is zero.
  • inventions of the present application provide a control system for a DC/DC converter.
  • the control system includes a DC power supply, a DC/DC converter, a DC load, and any possible implementation manner of the first aspect or in combination with the first aspect.
  • the controller in , wherein the input end of the DC/DC converter is coupled to the DC power supply, the output end of the DC/DC converter is coupled to the DC load, and the control end of the DC/DC converter is coupled to the controller.
  • FIG. 1 is a schematic diagram of voltage and current during switching of a switch tube provided by an embodiment of the present application
  • FIG. 3 is a circuit diagram of a DC/DC converter provided by an embodiment of the present application.
  • FIG. 4 is a control sequence diagram of the DC/DC converter provided by the embodiment of the present application.
  • FIG. 5 is a partial equivalent circuit diagram of the DC/DC converter provided by the embodiment of the present application.
  • FIG. 6 is a schematic diagram of an oscillating voltage provided by an embodiment of the present application.
  • FIG. 8 is another partial equivalent circuit diagram of the DC/DC converter provided by the embodiment of the present application.
  • FIG. 9 is another circuit diagram of the DC/DC converter provided by the embodiment of the present application.
  • FIG. 2 provides a control system of a DC/DC converter according to an embodiment of the present application.
  • the input end of the DC/DC converter 202 is coupled to the DC power source 201
  • the output end of the DC/DC converter 202 is coupled to the DC load 203
  • the control end of the DC/DC converter 202 is coupled to the controller 204 .
  • connection between A and B can be either a direct connection between A and B, or an indirect connection between A and B through one or more other electrical components, such as a direct connection between A and C, and a direct connection between C and B. , so that A and B are connected through C.
  • the DC power source 201 can be, for example, an energy storage battery (such as a nickel-cadmium battery, a nickel-hydrogen battery, a lithium-ion battery, a lithium-polymer battery, etc.), a solar battery, an AC/DC converter (Alternating Current/Direct-Current converter), or other DC/DC DC converters (such as BUCK converters, BOOST converters, BUCK-BOOST converters, etc.) and the like.
  • an energy storage battery such as a nickel-cadmium battery, a nickel-hydrogen battery, a lithium-ion battery, a lithium-polymer battery, etc.
  • a solar battery such as a nickel-cadmium battery, a nickel-hydrogen battery, a lithium-ion battery, a lithium-polymer battery, etc.
  • AC/DC converter Alternating Current/Direct-Current converter
  • other DC/DC DC converters such as BUCK converters, BOOST converters, BUCK-BOOST converters,
  • the DC/DC converter 202 in this embodiment of the present application may include, but is not limited to, an asymmetric half-bridge flyback converter, an asymmetric half-bridge forward converter, and the like.
  • the DC load 203 may be, for example, a mobile phone terminal, an energy storage battery, other DC/DC converters and/or a DC/AC converter (Direct-Current/Alternating Current converter), and the like.
  • DC/AC converter Direct-Current/Alternating Current converter
  • the controller 204 can be, for example, a central processing unit (CPU), other general-purpose processors, a digital signal processor (DSP), an application specific integrated circuit (ASIC), an off-the-shelf programmable gate Field-programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc.
  • CPU central processing unit
  • DSP digital signal processor
  • ASIC application specific integrated circuit
  • FPGA off-the-shelf programmable gate Field-programmable gate array
  • FPGA field-programmable gate array
  • the DC load 203 is a mobile phone terminal
  • the DC power source 201 is an AC/DC converter that converts the AC voltage of the grid into a DC voltage
  • the controller 204 can control the DC/DC converter 202 to output the DC voltage from the AC/DC converter Convert to a set DC voltage value, such as 5V, 10V, etc.
  • the DC/DC converter 202 and the controller 204 may be provided in a power adapter.
  • the above is an example of the usage scenarios of the DC/DC converter in the embodiment of the present application, and is not exhaustive. It should be understood that the controller in the embodiment of the present application can control the DC/DC converter to be applied in any scenario that requires DC voltage conversion.
  • FIG. 3 is a circuit diagram of a DC/DC converter provided by an embodiment of the present application.
  • the DC/DC converter includes a first switch Q L , a second switch Q H , a first capacitor C r and a transformer.
  • the transformer includes an excitation inductance L m and a transformer leakage inductance L r . It is understood that the magnetizing inductance, transformer leakage inductance and ideal transformer can be embodied as an actual transformer.
  • the DC/DC converter may further include a third switch tube Q 1 , an output capacitor C 0 , a load resistor R 0 and the like.
  • each switch tube is an example of a metal-oxide-semiconductor field-effect transistor (Metal-Oxide-Semiconductor Field-Effect Transistor, MOSFET). It should be understood that each switch tube may also be an insulated gate bipolar type. Transistor (Insulated Gate Bipolar Transistor, IGBT) and other semiconductor devices.
  • MOSFET Metal-oxide-semiconductor field-effect transistor
  • IGBT Insulated Gate Bipolar Transistor
  • the first switch QL and the second switch QH are connected in series and then coupled to both ends of the DC power supply V in , that is, the drain of the first switch QL is coupled to the source of the second switch QH , and the second switch
  • the drain of the transistor QH is coupled to the positive pole of the DC power supply V in
  • the source of the first switching tube QL is coupled to the negative pole of the DC power supply V in .
  • two ends of the DC power supply V in are connected in parallel with a filter capacitor C in .
  • the primary side of the transformer is connected in parallel with both ends of the first switch tube QL through the first capacitor Cr.
  • the drain of the first switch transistor QL is coupled to one end of the first capacitor Cr , the other end of the first capacitor Cr is coupled to one side of the primary side of the transformer, and the other side of the primary side of the transformer is coupled to the first switch transistor.
  • the source of QL is coupled to one end of the first capacitor Cr .
  • the secondary side of the transformer is coupled with a DC load, for example, one side of the secondary side of the transformer is coupled to the source of the third switch Q1, the drain of the third switch Q1 is coupled to one end of the output capacitor C0 and one end of the load resistor R0 , the other end of the output capacitor C 0 and the other end of the load resistor R 0 are coupled with the other side of the secondary side of the transformer, and the output capacitor C 0 can reduce the output voltage ripple of the DC/DC converter.
  • one side of the primary side of the transformer, such as the upper side, and the other side of the secondary side of the transformer, such as the lower side, are ends with the same name, or the other side of the primary side of the transformer, such as the lower side, and the side of the secondary side of the transformer.
  • the upper side is the end of the same name.
  • the load resistance R 0 is used to represent the DC load, and the embodiment of the present application does not limit the DC load coupled to the DC/DC converter.
  • the third switch tube Q1 can be replaced by a diode to realize the rectification function.
  • Each switch tube in the DC/DC converter such as the first switch tube QL , the second switch tube QH , etc., are all coupled to the controller (not shown in the figure).
  • the controller can control the on-off state of each switch tube.
  • FIG. 4 is a control sequence diagram of the DC/DC converter provided by the embodiment of the present application.
  • V g (Q L ) is the pulse waveform sent by the controller to the first switch tube QL
  • V g (Q H ) is the pulse waveform sent by the controller to the second switch tube Q H
  • V DS -QL is the voltage waveform across the first switch transistor QL
  • V DS-QH is the voltage waveform across the second switch transistor QH
  • I Lm is the current waveform of the excitation inductor Lm .
  • both the first switch transistor Q L and the second switch transistor Q H are in an off state, and a partial equivalent circuit diagram of the DC/DC converter can be seen in FIG. 5 .
  • the parasitic capacitance CL of the first switch QL and the parasitic capacitance CH of the second switch QH, the first capacitor Cr, the excitation inductance Lm and the transformer leakage inductance Lr form a resonance circuit.
  • the voltage across the first switch tube QL may be a stable resonance value, for example, the voltage across the first capacitor Cr .
  • the controller acquires the voltage across the first switch transistor QL when receiving the signal that the DC/DC converter enters the first state.
  • a voltage sensor is coupled to the output end of the DC/DC converter, and the voltage sensor generates a signal that the DC/DC converter enters the first state when the output voltage of the DC/DC converter is lower than a third preset voltage threshold, The signal is sent to the controller; for another example, the DC load coupled with the secondary side of the transformer can monitor the output voltage of the DC/DC converter in real time.
  • the DC load is an energy storage battery, and the energy storage battery is provided with a voltage monitoring function to monitor the output voltage of the DC/DC converter in real time.
  • the voltage threshold is preset, a signal for the DC/DC converter to enter the first state is generated, and the signal is sent to the controller, etc.
  • the embodiment of the present application does not limit how to generate a signal for the DC/DC converter to enter the first state .
  • the third preset voltage threshold and/or the fourth preset voltage threshold may be determined in advance according to the DC load.
  • the oscillating voltage across the first switch QL is the second preset voltage threshold
  • a high level is sent to the first switch QL (ie, the first switch QL is controlled to be turned on).
  • the above-mentioned oscillating voltage includes various periodic voltages.
  • FIG. 6 is a schematic diagram of the oscillating voltage provided by this embodiment of the present application.
  • each cycle voltage has a minimum voltage value corresponding to the cycle, for example, the voltage values corresponding to points a, b, and c shown in FIG. 6 .
  • the above-mentioned second preset voltage threshold may be the minimum voltage value in any period.
  • the controller when the controller receives a signal that the DC/DC converter enters the first state, the controller can monitor the voltage across the first switch transistor QL in real time, and determine that the voltage across the first switch transistor QL is within the period voltage For another example, when the controller detects that the voltage across the first switch tube QL is the target voltage value, after the target time period elapses, the voltage across the first switch tube QL drops to the current cycle At the minimum voltage value, the controller controls the first switch QL to turn on, and the target time period is related to the above-mentioned resonant circuit. When the voltage across the first switch QL is the minimum voltage value in any cycle, the first switch QL is controlled to be turned on, and the turn-on loss of the first switch QL is relatively small.
  • the controller controls the first switch QL to turn on at time t 0 , from time t 0 to t 1 , the first capacitor C r passes through the first switch QL , the excitation inductance L m and the transformer leakage inductance L r to form the first capacitor Cr.
  • the closed-loop, partial equivalent circuit diagram of the DC/DC converter can be seen in FIG. 7A.
  • the current of the excitation inductance L m increases in the first direction, that is, the current of the excitation inductance L m increases in the counterclockwise direction.
  • the clockwise direction is taken as the positive direction.
  • the current of the excitation inductance Lm increases in the negative direction.
  • the counterclockwise increase of the current of the magnetizing inductance Lm may be caused by the reflected voltage of the secondary side of the transformer (not shown in the figure) being applied across the magnetizing inductance Lm .
  • the turn-on time of the first switch tube QL is not accurate enough, and the current of the excitation inductance Lm may be in the forward direction at t 0 , and the excitation
  • the inductor L m current has a process of changing the current direction from t 0 to t 1 , that is, after decreasing to zero in the positive direction, it increases in the negative direction.
  • the time period from t 0 to t 1 may be a pre-calculated fixed value, for example, may be based on the parasitic value of the first capacitor C r and the first switch transistor QL
  • the capacitance C L , the parasitic capacitance CH of the second switch tube QH, the excitation inductance L m and the transformer leakage inductance L r are calculated and obtained.
  • the controller controls the first switch QL to be turned off. Since the inductor current cannot be abruptly changed, after the first switch QL is turned off, a partial equivalent circuit diagram of the DC/DC converter can be seen in FIG. 7B . As shown in FIG. 7B , the transformer leakage inductance L r and the excitation inductance L m charge the parasitic capacitance CL of the first switching transistor QL , and discharge the parasitic capacitance CH of the second switching transistor QH.
  • the current of the magnetizing inductance L m may increase to the target current along the first direction (ie, the counterclockwise direction), and at t In the time period from 1 to t 2 , the current of the excitation inductance L m may decrease from the target current clockwise to the second preset current threshold value after the first time period.
  • the voltage V DS-QH decreases to a first predetermined voltage threshold value over the same time period (ie, a first time period), which is not greater than the time period from t 1 to t 2 .
  • a first time period ie, a first time period
  • the DC/DC converter in the embodiment of the present application performs periodic switching from the second state to the first state.
  • a reference time period can be preset as the preset time period of the current cycle.
  • the second switch The voltage V DS-QH across the tube Q H has been reduced to the first preset voltage threshold, then the preset time period of the next cycle is adjusted to be smaller based on the preset time period of the current cycle;
  • the preset time period based on the current cycle will decrease the voltage V DS-QH.
  • the preset time period of one cycle is increased.
  • the time for the voltage V DS-QH across the second switching transistor Q H to decrease to the first preset voltage threshold and the time for the current of the excitation inductor L m to decrease to the second preset current threshold in the clockwise direction equal or close.
  • the controller sends a high-level signal to the second switch QH (that is, controls the second switch QH to be turned on), at this time, the voltage V DS-QH across the second switch QH is the first preset. Set the voltage threshold.
  • the second switch tube Q H is in an on state, and a partial equivalent circuit diagram of the DC/DC converter can be seen in FIG. 7C .
  • the DC power V in forms a second closed loop through the second switch tube Q H , the first capacitor C r , the transformer leakage inductance L r and the excitation inductance L m , and the DC/DC converter enters the first closed loop.
  • the current of the magnetizing inductance Lm increases in a second direction, which is opposite to the first direction.
  • the second direction is the clockwise direction (ie, the forward direction).
  • the first switch tube before the DC/DC converter enters the first state, the first switch tube is controlled to be turned on to provide a current in the negative direction to the second switch tube, and the voltage across the second switch tube is reduced to the first preset level. Setting the voltage threshold and implementing the embodiments of the present application can reduce the turn-on loss of the DC/DC converter.
  • the first preset voltage threshold is zero as an example.
  • the voltage V DS-QH across the second switching transistor Q H decreases to zero, and the voltage V DS-QL across the first switching transistor QL increases correspondingly to the voltage value of the DC power supply V in .
  • the parasitic capacitance CH of the second switching transistor QH is discharged from the start to the end of the discharge.
  • the parasitic diode DH of the second switch transistor QH is turned on after the discharge of the parasitic capacitor CH ( ie, time t2 ), so that the voltage V DS-QH across the second switch transistor QH is reduced to zero.
  • the controller controls the second switch tube Q H to be turned on, and the second switch tube Q H is turned on at zero voltage, which can be Reduce the turn-on loss of the DC/DC converter.
  • the controller sends at least two pulse waves to the first switching transistor QL and the second switching transistor QH respectively according to a preset period.
  • the controller sends the first switching transistors QL and QL respectively according to a preset period.
  • the second switch Q H sends two pulse waves.
  • the first switch Q L and the second switch Q H are alternately controlled to be turned on to provide the target power to the DC load, for example, at t 2
  • the second switch tube QH is controlled to be turned on from time t3 ; the first switch tube QL is controlled to be turned on from time t4 to t5 ; and the second switch tube QH is controlled to be turned on from time t6 to t7.
  • t 3 to t 4 and t 5 to t 6 are dead time.
  • the controller sends at least two pulse waves to the first switch tube and the second switch tube respectively according to a preset period, so that the DC/DC converter can greatly improve the performance of the DC/DC converter on the basis of reducing the turn-on loss. energy efficiency.
  • the first switch tube QL is controlled to be turned on.
  • the first capacitor C r The transformer leakage inductance L r , the excitation inductance L m and the first switch tube QL form a third closed loop, and a partial equivalent circuit diagram of the DC/DC converter can be seen in FIG. 8 .
  • the energy in the excitation inductance L m is directed to the first capacitor C r is transmitted, so that the current of the excitation inductance L m decreases in the second direction, that is, the current of the excitation inductance L m decreases in the clockwise direction.
  • the clockwise reduction of the current of the magnetizing inductance Lm may be caused by the reflected voltage of the secondary side of the transformer (not shown in the figure) being applied across the magnetizing inductance Lm .
  • the DC/DC converter receives 3 pulse waves in the first state as an example. After the controller sends 3 pulse waves, it controls the second switch tube Q H to turn off. After being turned off, the first switch tube QL is controlled to be turned on. It can be understood that the DC/DC converter is in the first state from time t 2 to time t 7 , and is in the second state after time t 9. It can be understood that the DC/DC converter switches from the first state to the second state.
  • the first switch QL is controlled to be turned on at time t8 , and the current of the excitation inductor Lm decreases clockwise. Small.
  • the switching from the first state of the DC/DC converter to the second state may be preset by the controller, that is, the number of pulse waves sent by the controller to the DC/DC converter may be preset .
  • the switching from the first state to the second state of the DC/DC converter may also be determined according to the state of the DC load, such as the current, voltage and/or power of the DC load.
  • the first switch transistor QL When the current of the excitation inductance L m is the first preset current threshold, the first switch transistor QL is controlled to be turned off, so that the DC/DC converter enters the second state.
  • the control of the first switch tube is increased by increasing the control of the first switch tube after the DC/DC converter is switched from the first state to the second state and after the second switch tube is turned off. is turned on, the energy stored in the leakage inductance of the transformer can be transferred to the DC load, thereby improving the energy utilization rate; and the first switch tube is turned off when the current of the excitation inductance Lm is the first preset current threshold, which can reduce the When a switch tube is turned off, the voltage at both ends of the switch tube oscillates, reducing the electromagnetic interference of the DC/DC converter.
  • the controller controls the first switching transistor Q L Turn off, at this time, the first switch tube QL can realize zero current turn off.
  • the controller can obtain the current of the excitation inductance L m in real time, so as to determine that the current of the excitation inductance L m is reduced to zero; for another example, the controller can also calculate the excitation inductance according to the resonance state and circuit parameters of the DC/DC converter The target time at which the current of Lm is reduced to zero.
  • This embodiment of the present application does not limit how to determine that the current of the excitation inductance L m is reduced to the first preset current threshold.
  • FIG. 9 is another circuit diagram of the DC/DC converter provided by the embodiment of the present application.
  • the DC/DC converter includes a first switch transistor Q H1 , a second switch transistor Q L1 , a first capacitor C r1 , and a transformer.
  • the transformer includes an excitation inductance L m1 and a transformer leakage inductance L r1 .
  • the DC/DC converter may further include a third switch transistor Q 2 , an output capacitor C 01 , a load resistor R 01 and the like.
  • the source of the first switch tube Q H1 is coupled to the drain of the second switch tube Q L1 , the drain of the first switch tube Q H1 is coupled to the positive pole of the DC power supply V in1 , and the source of the second switch tube Q L1 is coupled to the DC power supply Negative terminal of V in1 .
  • two ends of the DC power supply V in1 are connected in parallel with a filter capacitor C in1 .
  • the primary side of the transformer is connected in parallel with both ends of the first switch tube Q H1 through the first capacitor C r1 .
  • the drain of the first switch transistor Q H1 is coupled to one end of the first capacitor C r1 , the other end of the first capacitor C r1 is coupled to one side of the primary side of the transformer, and the other side of the primary side of the transformer is coupled to the first switch transistor The source of Q H1 .
  • the secondary side of the transformer is coupled with a DC load, for example, one side of the secondary side of the transformer is coupled to the source of the third switch Q2 , and the drain of the third switch Q2 is coupled to one end of the output capacitor C01 and one end of the load resistor R01 , the other end of the output capacitor C 01 and the other end of the load resistor R 01 are coupled with the other side of the secondary side of the transformer, and the output capacitor C 01 can reduce the output voltage ripple of the DC/DC converter.
  • one side of the primary side of the transformer, such as the upper side, and the other side of the secondary side of the transformer, such as the lower side, are ends with the same name, or the other side of the primary side of the transformer, such as the lower side, and the side of the secondary side of the transformer.
  • the upper side is the end of the same name.
  • the DC/DC converter shown in FIG. 9 can also adopt the control timing diagram shown in FIG. 4 , except that V g (Q L ) is changed to the pulse sent by the controller to the first switch tube Q H1 The waveform, V g (Q H ) is changed to the pulse waveform sent by the controller to the second switch tube Q L1 .
  • V g (Q L ) is changed to the pulse sent by the controller to the first switch tube Q H1
  • V g (Q H ) is changed to the pulse waveform sent by the controller to the second switch tube Q L1 .
  • the DC/DC converter shown in FIG. 9 can implement any of the possible implementations described above in conjunction with FIGS. 3 to 8 , and can also achieve the above beneficial effects.
  • Each functional unit in each embodiment of the present invention may be all integrated into one processing unit, or each unit may be separately used as a unit, or two or more units may be integrated into one unit; the above-mentioned integrated units It can be implemented in the form of hardware or in the form of hardware plus software functional units.
  • the integrated units of the present invention are implemented in the form of software function modules and sold or used as independent products, they may also be stored in a computer-readable storage medium.
  • the computer software products are stored in a storage medium and include several instructions for A computer device (which may be a personal computer, a server, or a network device, etc.) is caused to execute all or part of the methods described in the various embodiments of the present invention.
  • the aforementioned storage medium includes: a removable storage device, a ROM, a RAM, a magnetic disk or an optical disk and other mediums that can store program codes.

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Abstract

本申请提供了一种DC/DC变换器的控制器及其控制系统，DC/DC变换器包括第一开关管、第二开关管、第一电容以及变压器，该变压器包含励磁电感和变压器漏感；控制器控制第一开关管开通，以形成第一闭合回路，励磁电感的电流沿第一方向增大；控制器在预设时间段之后，控制第一开关管关断，以使第二开关管两端的电压减小；控制器在第二开关管两端的电压为第一预设电压阈值的情况下，控制第二开关管开通，以形成第二闭合回路，此时DC/DC变换器进入第一状态，励磁电感的电流沿第二方向增大，其中第二方向与第一方向相反。实施本申请实施例，可以降低DC/DC变换器中的开通损耗。

Description

DC/DC变换器的控制器及其控制系统
本申请要求于2021年02月10日提交中国专利局、申请号为202110184240.1、申请名称为“DC/DC变换器的控制器及其控制系统”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及电源技术领域，尤其是一种DC/DC变换器的控制器及其控制系统。
背景技术
DC/DC变换器(Direct-Current/Direct-Current converter)包括开关管、电感和电容等，通过控制开关管的通断来对电感和电容进行充放电，从而将输入直流电压转换为设定的直流电压。然而开关管在通断过程中是存在开关损耗的，参见图1，图1为本申请实施例提供的开关管开关过程中电压与电流的示意图。如图1所示，在开关管开通的过程中，开关管电流上升与开关管电压下降有一个交叠区产生开通损耗，该开通损耗可以理解为开关管从截止到导通时所产生的功率损耗。同理的，在开关管关断的过程中，开关管电流下降与开关管电压上升也有一个交叠区产生关断损耗，该关断损耗可以理解为开关管从导通到截止时所产生的功率损耗。
随着节能的深入，电源产品的效率不断提高，如何降低DC/DC变换器中开关管的损耗是重点研究的问题。
发明内容
本申请实施例提供了一种DC/DC变换器的控制器及其控制系统，可以降低DC/DC变换器中的损耗。
第一方面，本申请实施例提供了一种DC/DC变换器的控制器，其中该控制器与上述DC/DC变换器耦合，该DC/DC变换器包括第一开关管、第二开关管、第一电容以及变压器，该变压器包含励磁电感和变压器漏感；上述第一开关管与上述第二开关管串联之后耦合在直流电源的两端，上述变压器的原边通过上述第一电容并联在上述第一开关管的两端，上述变压器的副边耦合有直流负载，其中，
上述控制器控制所述第一开关管开通，以使上述第一电容经过上述第一开关管与上述励磁电感以及上述变压器漏感形成第一闭合回路，上述励磁电感的电流沿第一方向增大；
上述控制器在预设时间段之后，控制上述第一开关管关断，以使上述第二开关管两端的电压减小；
上述控制器在上述第二开关管两端的电压为第一预设电压阈值的情况下，控制上述第二开关管开通，以使上述直流电源经过上述第二开关管、上述第一电容、上述变压器漏感以及上述励磁电感形成第二闭合回路，此时上述DC/DC变换器进入第一状态，上述励磁电感的电流沿第二方向增大，其中上述第二方向与上述第一方向相反。
本申请实施例中，在DC/DC变换器进入第一状态之前，先控制第一开关管开通以向第二开关管提供负向方向的电流，减小第二开关管两端的电压至第一预设电压阈值，实施本 申请实施例，可以降低DC/DC变换器的开通损耗。
结合第一方面，在第一种可能的实现方式中，上述控制器在上述DC/DC变换器进入第一状态之后，按照预设周期分别向上述第一开关管和上述第二开关管发送至少两个脉冲波，使得上述DC/DC变换器向上述直流负载提供目标功率。
在本申请实施例中，控制器按照预设周期分别向第一开关管和第二开关管发送至少两个脉冲波，从而可以使得DC/DC变换器在降低开通损耗的基础上，大大提高了能量利用效率。
结合第一方面第一种可能的实现方式，在第二种可能的实现方式中，上述控制器在上述DC/DC变换器从上述第一状态切换至第二状态之间，当上述第二开关管关断之后，控制上述第一开关管开通，此时上述第一电容、上述变压器漏感、上述励磁电感以及上述第一开关管形成第三闭合回路，上述励磁电感的电流沿上述第二方向减小；
上述控制器在上述励磁电感的电流减小至第一预设电流阈值时，控制上述第一开关管关断。
本申请实施例中，通过在DC/DC变换器从第一状态切换至第二状态之间，且在第二开关管关断之后，增加对第一开关管的控制，即控制第一开关管开通，可以将变压器漏感中存储的能量传输至直流负载，从而提高能量利用率；并在励磁电感的电流减小至第一预设电流阈值时才关断第一开关管，可以减小第一开关管关断时开关管两端电压的振荡，减小DC/DC变换器的电磁干扰。
结合第一方面第二种可能的实现方式，在第三种可能的实现方式中，上述第二状态为上述第一开关管和上述第二开关管均处于关断状态，上述第一开关管的寄生电容和上述第二开关管的寄生电容与上述第一电容、上述励磁电感以及上述变压器漏感形成谐振回路。
结合第一方面或结合第一方面上述任一可能的实现方式，在第四种可能的实现方式中，在上述控制器控制上述第一开关管开通之前，上述第一开关管的寄生电容和上述第二开关管的寄生电容与上述第一电容、上述励磁电感以及上述变压器漏感形成谐振回路，上述第一开关管两端的电压为振荡电压；
上述控制器在接收到上述DC/DC变换器进入上述第一状态的信号时，获取上述第一开关管两端的电压；
上述控制器在上述第一开关管两端的振荡电压为第二预设电压阈值时，控制上述第一开关管开通。
结合第一方面第四种可能的实现方式，在第五种可能的实现方式中，上述振荡电压包括各个周期电压，上述第二预设电压阈值为任一周期电压中的最小电压值。
结合第一方面第四种可能的实现方式，在第六种可能的实现方式中，上述DC/DC变换器进入上述第一状态的信号为根据上述DC/DC变换器的输出电压确定的。
结合第一方面或结合第一方面上述任一可能的实现方式，在七种可能的实现方式中，上述第二开关管两端的电压经过第一时间段减小至上述第一预设电压阈值；
上述励磁电感的电流经过上述第一时间段从目标电流减小至第二预设电流阈值，上述目标电流为上述励磁电感的电流经过上述预设时间段之后增大得到的。
结合第一方面或结合第一方面上述任一可能的实现方式，在第八种可能的实现方式中， 上述第一预设电压阈值为零。
结合第一方面或结合第一方面上述任一可能的实现方式，在第九种可能的实现方式中，上述第一预设电流阈值为零。
第二方面，本申请实施例提供了一种DC/DC变换器的控制系统，该控制系统包括直流电源、DC/DC变换器、直流负载以及第一方面或结合第一方面任一可能实现方式中的控制器，其中上述DC/DC变换器的输入端耦合上述直流电源，上述DC/DC变换器的输出端耦合上述直流负载，上述DC/DC变换器的控制端耦合上述控制器。
应理解的是，本申请上述多个方面的实现和有益效果可互相参考。
附图说明
图1为本申请实施例提供的开关管开关过程中电压与电流的示意图；
图2为本申请实施例提供的一种DC/DC变换器的控制系统；
图3为本申请实施例提供的DC/DC变换器的一电路图；
图4为本申请实施例提供的DC/DC变换器的一控制时序图；
图5为本申请实施例提供的DC/DC变换器的一部分等效电路图；
图6为本申请实施例提供的振荡电压的示意图；
图7A-图7C分别为本申请实施例提供的DC/DC变换器的又一部分等效电路图；
图8为本申请实施例提供的DC/DC变换器的又一部分等效电路图；
图9为本申请实施例提供的DC/DC变换器的又一电路图。
具体实施方式
下面结合附图来对本申请的技术方案的实施作进一步的详细描述。
参见图2，图2为本申请实施例提供的一种DC/DC变换器的控制系统。如图2所示，DC/DC变换器202的输入端耦合直流电源201，DC/DC变换器202的输出端耦合直流负载203，DC/DC变换器202的控制端耦合控制器204。
需要首先指出的是，本申请中所描述的“耦合”指的是直接或间接连接。例如，A与B连接，既可以是A与B直接连接，也可以是A与B之间通过一个或多个其它电学元器件间接连接，例如可以是A与C直接连接，C与B直接连接，从而使得A与B之间通过C实现了连接。
直流电源201可以例如是储能电池(如镍镉电池、镍氢电池、锂离子电池、锂聚合物电池等)、太阳能电池、AC/DC变换器(Alternating Current/Direct-Currentconverter)或其他DC/DC变换器(例如BUCK变换器、BOOST变换器、BUCK-BOOST变换器等)等。
本申请实施例中的DC/DC变换器202可以包括但不限于非对称半桥反激变换器、非对称半桥正激变换器等。
直流负载203可以例如是手机终端、储能电池、其他DC/DC变换器和/或DC/AC变换器(Direct-Current/Alternating Currentconverter)等。
控制器204例如可以是中央处理单元(central processing unit，CPU)、其他通用处理器、数字信号处理器(digital signal processor，DSP)、专用集成电路(application specific integrated circuit，ASIC)、现成可编程门阵列(field-programmable gate array，FPGA)或者其他可编程逻 辑器件、分立门或者晶体管逻辑器件、分立硬件组件等。
例如，直流负载203是手机终端，直流电源201是将电网交流电压转换为直流电压的AC/DC变换器，控制器204可以控制DC/DC变换器202将该AC/DC变换器输出的直流电压转换为设定的直流电压值，例如5V、10V等。示例性的，DC/DC变换器202和控制器204可以设置在电源适配器中。上述为对本申请实施例DC/DC变换器的使用场景进行示例，而非穷举，应当理解为本申请实施例中控制器可以控制DC/DC变换器应用在任何需要对直流电压转换的场景。
参见图3，图3为本申请实施例提供的DC/DC变换器的一电路图。如图3所示，DC/DC变换器包括第一开关管Q L、第二开关管Q H、第一电容C r以及变压器，该变压器包含励磁电感L m和变压器漏感L r。可以理解的是，励磁电感、变压器漏感和理想变压器可以具体实现为一个实际变压器。进一步的，DC/DC变换器还可以包括第三开关管Q 1、输出电容C 0以及负载电阻R 0等。
本申请实施例以各个开关管为金属氧化物半导体场效应管(Metal-Oxide-Semiconductor Field-Effect Transistor,MOSFET)进行示例性说明，应当理解的是，各个开关管还可以是绝缘栅双极型晶体管(Insulated Gate Bipolar Transistor，IGBT)等其他半导体器件。
第一开关管Q L与第二开关管Q H串联之后耦合在直流电源V in的两端，即第一开关管Q L的漏极与第二开关管Q H的源极耦合，第二开关管Q H的漏极耦合直流电源V in的正极，第一开关管Q L的源极耦合直流电源V in的负极。可选的，直流电源V in的两端并联有滤波电容C in。变压器的原边通过第一电容C r并联在第一开关管Q L的两端。示例性的，第一开关管Q L的漏极耦合第一电容C r的一端，第一电容C r的另一端耦合变压器原边的一侧，变压器原边的另一侧耦合第一开关管Q L的源极。变压器的副边耦合有直流负载，例如变压器副边的一侧耦合第三开关管Q 1的源极，第三开关管Q 1的漏极耦合输出电容C 0的一端以及负载电阻R 0的一端，输出电容C 0的另一端以及负载电阻R 0的另一端与变压器副边的另一侧耦合，输出电容C 0可以减小DC/DC变换器的输出电压纹波。示例性的，上述变压器原边的一侧例如上侧与上述变压器副边的另一侧例如下侧是同名端，或者上述变压器原边的另一侧例如下侧与上述变压器副边的一侧例如上侧是同名端。
可以理解的是，图3中以负载电阻R 0代表直流负载，本申请实施例不对DC/DC变换器耦合的直流负载进行限制。第三开关管Q 1可以由二极管代替实现整流功能。
该DC/DC变换器中的各个开关管例如第一开关管Q L、第二开关管Q H等均与控制器耦合(图中未示出)。该控制器可以控制各个开关管的通断状态。
控制器对DC/DC变换器中各个开关管的通断控制时序可以参见图4，图4为本申请实施例提供的DC/DC变换器的一控制时序图。如图4所示，V g(Q L)为控制器向第一开关管Q L发送的脉冲波形、V g(Q H)为控制器向第二开关管Q H发送的脉冲波形，V DS-QL为第一开关管Q L两端的电压波形，V DS-QH为第二开关管Q H两端的电压波形，I Lm为励磁电感L m的电流波形。
在t 0时刻之前，第一开关管Q L和第二开关管Q H均处于关断状态，DC/DC变换器的部分等效电路图可以参见图5。如图5所示，第一开关管Q L的寄生电容C L和第二开关管Q H的寄生电容C H与第一电容C r、励磁电感L m以及变压器漏感L r形成谐振回路。可选的，在该谐振回路达到谐振稳定之后，第一开关管Q L两端的电压可以是一个稳定谐振值，例如为第一电容C r两端的电压值。
在一些可行的实施方式中，控制器在接收到DC/DC变换器进入第一状态的信号时，获取第一开关管Q L两端的电压。例如，该DC/DC变换器的输出端耦合有电压传感器，该电压传感器在DC/DC变换器的输出电压低于第三预设电压阈值时生成DC/DC变换器进入第一状态的信号，并将该信号发送至控制器；又例如，与变压器的副边耦合的直流负载可以实时监测DC/DC变换器的输出电压。例如该直流负载是储能电池，该储能电池中设置有电压监测功能，实时监测DC/DC变换器的输出电压，当DC/DC变换器的输出电压在预设时间范围内降低至第四预设电压阈值时，生成DC/DC变换器进入第一状态的信号，并将该信号发送至控制器等等，本申请实施例不对如何生成DC/DC变换器进入第一状态的信号进行限制。可选的，上述第三预设电压阈值和/或上述第四预设电压阈值可以是预先根据直流负载确定的。
在第一开关管Q L两端的振荡电压为第二预设电压阈值时，向第一开关管Q L发送高电平(即控制第一开关管Q L开通)。
在一些可行的实施方式中，上述振荡电压包括各个周期电压，参见图6，图6为本申请实施例提供的振荡电压的示意图。如图6所示，每个周期电压中均有该周期对应的最小电压值例如图6中示出的a、b、c点对应的电压值。上述第二预设电压阈值可以是任一周期中的最小电压值。例如，在控制器接收到DC/DC变换器进入第一状态的信号时，控制器可以实时监测第一开关管Q L两端的电压，确定第一开关管Q L两端的电压是该周期电压中的 最小值；又例如，控制器在检测到第一开关管Q L两端的电压为目标电压值时，经过目标时间段之后，此时第一开关管Q L两端的电压下降至当前周期中的最小电压值，控制器控制第一开关管Q L开通，该目标时间段与上述谐振回路有关。在第一开关管Q L两端的电压为任一周期中的最小电压值时，控制第一开关管Q L开通，第一开关管Q L的开通损耗相对较小的。
控制器在t 0时刻控制第一开关管Q L开通之后，在t 0至t 1时刻，第一电容C r经过第一开关管Q L与励磁电感L m以及变压器漏感L r形成第一闭合回路，DC/DC变换器的部分等效电路图可以参见图7A。如图7A所示，励磁电感L m的电流沿第一方向增大，即励磁电感L m的电流沿逆时针方向增大。本申请实施例中以顺时针方向为正方向，结合图4中示出的励磁电感L m的电流波形I Lm可知，励磁电感L m的电流是负向增大的。在一些可行的实施方式中，励磁电感L m的电流沿逆时针方向增大可以是由变压器副边(图中未示出)的反射电压加在励磁电感L m的两端导致的。
可以理解的是，由于系统检测误差和/或系统控制误差，第一开关管Q L开通的时间不够准确，该励磁电感L m的电流在t 0的振荡电流方向可能为正向方向，则励磁电感L m电流在t 0至t 1时刻存在电流方向改变的过程，即沿正向方向减小至零之后，沿负向方向增大。
在一些可行的实施方式中，t 0至t 1的时间段(即预设时间段)可以是预先计算好的固定值，比如可以是根据第一电容C r、第一开关管Q L的寄生电容C L、第二开关管Q H的寄生电容C H、励磁电感L m以及变压器漏感L r等计算得到的。
在t 1时刻，控制器控制第一开关管Q L关断。由于电感电流不可突变，在第一开关管Q L关断之后，DC/DC变换器的部分等效电路图可以参见图7B。如图7B所示，变压器漏感L r和励磁电感L m向第一开关管Q L的寄生电容C L充电，向第二开关管Q H的寄生电容C H放电。
t 1至t 2时刻，第一开关管Q L两端的电压V DS-QL增大，第二开关管Q H两端的电压V DS-QH减小。在一些可行的实施方式中，在t 0至t 1的时间段(即预设时间段)，励磁电感L m的电流可以沿第一方向(即逆时针方向)增大到目标电流，在t 1至t 2的时间段中，励磁电感L m的电流可以是经过第一时间段从目标电流沿顺时针方向减小至第二预设电流阈值，此时，第二 开关管Q H两端的电压V DS-QH经过相同的时间(即第一时间段)减小至第一预设电压阈值，该第一时间段不大于t 1至t 2的时间段。示例性的，本申请实施例的DC/DC变换器在第二状态向第一状态进行周期切换。可以预先设置一个参考时间段作为当前周期的预设时间段，在该预设时间段内，若励磁电感L m的电流沿顺时针方向减小至第二预设电流阈值时，而第二开关管Q H两端的电压V DS-QH已经减小至第一预设电压阈值，则基于当前周期的预设时间段将下一周期的预设时间段调小；若励磁电感L m的电流沿顺时针方向减小至第二预设电流阈值时，而第二开关管Q H两端的电压V DS-QH没有减小至第一预设电压阈值，则基于当前周期的预设时间段将下一周期的预设时间段调大。换句话说，第二开关管Q H两端的电压V DS-QH减小至第一预设电压阈值的时间与励磁电感L m的电流沿顺时针方向减小至第二预设电流阈值的时间相等或接近。以第一预设电压阈值是零、第二预设电流阈值是零为例，可以理解为励磁电感L m上的能量刚好放完时，第二开关管Q H的寄生二极管D H导通，提高能量利用效率。
在t 2时刻，控制器向第二开关管Q H发送高电平信号(即控制第二开关管Q H开通)，此时第二开关管Q H两端的电压V DS-QH为第一预设电压阈值。
在t 2至t 3时刻，第二开关管Q H处于导通状态，DC/DC变换器的部分等效电路图可以参见图7C。如图7C所示，直流电源V in经过第二开关管Q H、第一电容C r、变压器漏感L r以及励磁电感L m形成第二闭合回路，此时DC/DC变换器进入第一状态，励磁电感L m的电流沿第二方向增大，该第二方向与第一方向相反。换句话说，该第二方向是顺时针方向(即正向方向)。
本申请实施例，在DC/DC变换器进入第一状态之前，先控制第一开关管开通以向第二开关管提供负向方向的电流，减小第二开关管两端的电压至第一预设电压阈值，实施本申请实施例，可以降低DC/DC变换器的开通损耗。
示例性的，以图4中示出该第一预设电压阈值是零为例。在t 1至t 2时刻，第二开关管Q H两端的电压V DS-QH减小至零，第一开关管Q L两端的电压V DS-QL相应增大至直流电源V in的电压值。在t 1至t 2时刻内第二开关管Q H的寄生电容C H从开始放电到放电结束。第二开关管Q H的 寄生二极管D H在寄生电容C H放电结束之后(即t 2时刻)导通，使得第二开关管Q H两端的电压V DS-QH减小至零。本申请实施例中，控制器在第二开关管Q H两端的电压V DS-QH减小至零时，控制第二开关管Q H开通，第二开关管Q H实现了零电压开通，可以降低DC/DC变换器的开通损耗。
进一步的，在DC/DC变换器进入第一状态之后，控制器按照预设周期分别向第一开关管Q L和第二开关管Q H发送至少两个脉冲波。具体实现中，可以结合图4中示出的t 2至t 8时刻，以DC/DC变换器在t 2时刻进入第一状态之后，控制器按照预设周期分别向第一开关管Q L和第二开关管Q H发送两个脉冲波为例，在t 2至t 7时刻，交替控制第一开关管Q L和第二开关管Q H开通以向直流负载提供目标功率，例如在t 2至t 3时刻控制第二开关管Q H开通；t 4至t 5时刻控制第一开关管Q L开通；t 6至t 7时刻控制第二开关管Q H开通。其中t 3至t 4、t 5至t 6均为死区时间。
在本申请实施例中，控制器按照预设周期分别向第一开关管和第二开关管发送至少两个脉冲波，从而可以使得DC/DC变换器在降低开通损耗的基础上，大大提高了能量利用效率。
更进一步的，在DC/DC变换器从第一状态切换至第二状态之间，当第二开关管Q H关断之后，控制第一开关管Q L开通，此时第一电容C r、变压器漏感L r、励磁电感L m以及第一开关管Q L形成第三闭合回路，DC/DC变换器的部分等效电路图可以参见图8，励磁电感L m中的能量向第一电容C r传输，使得励磁电感L m的电流沿第二方向减小，即励磁电感L m的电流沿顺时针方向减小。在一些可行的实施方式中，励磁电感L m的电流沿顺时针方向减小可以是由变压器副边(图中未示出)的反射电压加在励磁电感L m的两端导致的。结合图4来对具体实现进行说明，图4中以DC/DC变换器在第一状态中接收3个脉冲波为例，控制器在发送完3个脉冲波，控制第二开关管Q H关断之后，控制第一开关管Q L开通。可以理解的是，DC/DC变换器在t 2至t 7时刻处于第一状态，t 9时刻之后处于第二状态，DC/DC变换器从第一状态切换至第二状态之间即可以理解为t 7至t 9时刻之间。当第二开关管Q H关断之后，经过一段死区时间(即t 7至t 8)之后，在t 8时刻控制第一开关管Q L开通，励磁电感L m的电流 沿顺时针方向减小。
在一些可行的实施方式中，DC/DC变换器的第一状态向第二状态进行切换可以是控制器预先设置好的，即控制器向DC/DC变换器发送的脉冲波数量可以是预先设置。可选的，DC/DC变换器的第一状态向第二状态进行切换还可以是根据直流负载的状态确定，比如直流负载的电流、电压和/或功率等。
在励磁电感L m的电流为第一预设电流阈值时，控制第一开关管Q L关断，以使DC/DC变换器进入第二状态。
本申请实施例中，通过在DC/DC变换器从第一状态切换至第二状态之间，且在第二开关管关断之后，增加对第一开关管的控制，即控制第一开关管开通，可以将变压器漏感中存储的能量传输至直流负载，从而提高能量利用率；并在励磁电感L m的电流为第一预设电流阈值时才关断第一开关管，可以减小第一开关管关断时开关管两端电压的振荡，减小DC/DC变换器的电磁干扰。
可选的，在一些可行的实施方式中，以图4中示出第一预设电流阈值是零为例，励磁电感L m的电流减小至零时，控制器控制第一开关管Q L关断，此时第一开关管Q L可以实现零电流关断。例如，控制器可以实时获取励磁电感L m的电流，从而确定励磁电感L m的电流减小至零；又例如，控制器还可以根据DC/DC变换器的谐振状态和电路参数来计算励磁电感L m的电流减小至零的目标时间。本申请实施例不对如何确定励磁电感L m的电流减小至第一预设电流阈值进行限制。
参见图9，图9为本申请实施例提供的DC/DC变换器的另一电路图。如图9所示，DC/DC变换器包括第一开关管Q H1、第二开关管Q L1、第一电容C r1以及变压器，该变压器包含励磁电感L m1和变压器漏感L r1。进一步的，DC/DC变换器还可以包括第三开关管Q 2、输出电容C 01以及负载电阻R 01等。
该DC/DC变换器与前文图3中示出的DC/DC变换器的区别在于，第一开关管与第二开关管的位置互换。
第一开关管Q H1的源极与第二开关管Q L1的漏极耦合，第一开关管Q H1的漏极耦合直流电源V in1的正极，第二开关管Q L1的源极耦合直流电源V in1的负极。可选的，直流电源V in1的两端并联有滤波电容C in1。变压器的原边通过第一电容C r1并联在第一开关管Q H1的两端。示例性的，第一开关管Q H1的漏极耦合第一电容C r1的一端，第一电容C r1的另一端耦合变压器 原边的一侧，变压器原边的另一侧耦合第一开关管Q H1的源极。变压器的副边耦合有直流负载，例如变压器副边的一侧耦合第三开关管Q 2的源极，第三开关管Q 2的漏极耦合输出电容C 01的一端以及负载电阻R 01的一端，输出电容C 01的另一端以及负载电阻R 01的另一端与变压器副边的另一侧耦合，输出电容C 01可以减小DC/DC变换器的输出电压纹波。示例性的，上述变压器原边的一侧例如上侧与上述变压器副边的另一侧例如下侧是同名端，或者上述变压器原边的另一侧例如下侧与上述变压器副边的一侧例如上侧是同名端。
具体实现中，图9中示出的DC/DC变换器也可以采用图4中示出的控制时序图，只是将V g(Q L)改为控制器向第一开关管Q H1发送的脉冲波形、V g(Q H)改为控制器向第二开关管Q L1发送的脉冲波形。该DC/DC变换器在各个不同时刻的等效电路可以参考前文结合图5至图8所描述的实施例，此处不作赘述。
可以理解的是，图9中示出的DC/DC变换器可以实现前文结合图3至图8所描述的任一可能的实施方式，也可以达到上述有益效果。
需要说明的是，上述术语“第一”、“第二”仅用于描述目的，而不能理解为指示或暗示相对重要性。
在本发明各实施例中的各功能单元可以全部集成在一个处理单元中，也可以是各单元分别单独作为一个单元，也可以两个或两个以上单元集成在一个单元中；上述集成的单元既可以采用硬件的形式实现，也可以采用硬件加软件功能单元的形式实现。
本发明上述集成的单元如果以软件功能模块的形式实现并作为独立的产品销售或使用时，也可以存储在一个计算机可读取存储介质中。基于这样的理解，本发明实施例的技术方案本质上或者说对现有技术做出贡献的部分可以以软件产品的形式体现出来，该计算机软件产品存储在一个存储介质中，包括若干指令用以使得一台计算机设备(可以是个人计算机、服务器、或者网络设备等)执行本发明各个实施例所述方法的全部或部分。而前述的存储介质包括：移动存储设备、ROM、RAM、磁碟或者光盘等各种可以存储程序代码的介质。
以上所述，仅为本发明的具体实施方式，但本发明的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本发明揭露的技术范围内，可轻易想到变化或替换，都应涵盖在本发明的保护范围之内。因此，本发明的保护范围应以所述权利要求的保护范围为准。

Claims (11)

  1. 一种DC/DC变换器的控制器，其中所述控制器与所述DC/DC变换器耦合，所述DC/DC变换器包括第一开关管、第二开关管、第一电容以及变压器，所述变压器包含励磁电感和变压器漏感；所述第一开关管与所述第二开关管串联之后耦合在直流电源的两端，所述变压器的原边通过所述第一电容并联在所述第一开关管的两端，所述变压器的副边耦合有直流负载，其特征在于，
    所述控制器，用于控制所述第一开关管开通，以使所述第一电容经过所述第一开关管与所述励磁电感以及所述变压器漏感形成第一闭合回路，所述励磁电感的电流沿第一方向增大；
    所述控制器，还用于在预设时间段之后，控制所述第一开关管关断，以使所述第二开关管两端的电压减小；
    所述控制器，还用于在所述第二开关管两端的电压为第一预设电压阈值的情况下，控制所述第二开关管开通，以使所述直流电源经过所述第二开关管、所述第一电容、所述变压器漏感以及所述励磁电感形成第二闭合回路，此时所述DC/DC变换器进入第一状态，所述励磁电感的电流沿第二方向增大，其中所述第二方向与所述第一方向相反。
  2. 根据权利要求1所述的控制器，其特征在于，所述控制器，还用于在所述DC/DC变换器进入第一状态之后，按照预设周期分别向所述第一开关管和所述第二开关管发送至少两个脉冲波，使得所述DC/DC变换器向所述直流负载提供目标功率。
  3. 根据权利要求2所述的控制器，其特征在于，所述控制器，还用于在所述DC/DC变换器从所述第一状态切换至第二状态之间，当所述第二开关管关断之后，控制所述第一开关管开通，此时所述第一电容、所述变压器漏感、所述励磁电感以及所述第一开关管形成第三闭合回路，所述励磁电感的电流沿所述第二方向减小；
    所述控制器，还用于在所述励磁电感的电流减小至第一预设电流阈值时，控制所述第一开关管关断。
  4. 根据权利要求3所述的控制器，其特征在于，所述第二状态为所述第一开关管和所述第二开关管均处于关断状态，所述第一开关管的寄生电容和所述第二开关管的寄生电容与所述第一电容、所述励磁电感以及所述变压器漏感形成谐振回路。
  5. 根据权利要求1-4任一项所述的控制器，其特征在于，在所述控制器控制所述第一开关管开通之前，所述第一开关管的寄生电容和所述第二开关管的寄生电容与所述第一电容、所述励磁电感以及所述变压器漏感形成谐振回路，所述第一开关管两端的电压为振荡电压；
    所述控制器，还用于在接收到所述DC/DC变换器进入所述第一状态的信号时，获取所述第一开关管两端的电压；
    所述控制器，还用于在所述第一开关管两端的振荡电压为第二预设电压阈值时，控制 所述第一开关管开通。
  6. 根据权利要求5所述的控制器，其特征在于，所述振荡电压包括各个周期电压，所述第二预设电压阈值为任一周期电压中的最小电压值。
  7. 根据权利要求5所述的控制器，其特征在于，所述DC/DC变换器进入所述第一状态的信号为根据所述DC/DC变换器的输出电压确定的。
  8. 根据权利要求1-7任一项所述的控制器，其特征在于，所述第二开关管两端的电压经过第一时间段减小至所述第一预设电压阈值；
    所述励磁电感的电流经过所述第一时间段从目标电流减小至第二预设电流阈值，所述目标电流为所述励磁电感的电流经过所述预设时间段之后增大得到的。
  9. 根据权利要求1-8任一项所述的控制器，其特征在于，所述第一预设电压阈值为零。
  10. 根据权利要求3-8任一项所述的控制器，其特征在于，所述第一预设电流阈值为零。
  11. 一种DC/DC变换器的控制系统，其特征在于，所述控制系统包括直流电源、所述DC/DC变换器、直流负载以及如权利要求1-10任一项所述的控制器，其中所述DC/DC变换器的输入端耦合所述直流电源，所述DC/DC变换器的输出端耦合所述直流负载，所述DC/DC变换器的控制端耦合所述控制器。
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