Controller, power supply device and control system for asymmetrical half-bridge converter

Abstract

The application provides a controller of an asymmetric half-bridge converter, a power supply device and a control system, wherein the asymmetric half-bridge converter comprises a first switch tube and a second switch tube; the controller controls the first switch tube to be turned on for a preset time period before controlling the first switch tube and the second switch tube to be turned on alternately, and controls the second switch tube to be turned on according to a comparison result of a voltage across the second switch tube and a first preset voltage threshold after controlling the first switch tube to be turned off. By implementing the embodiment of the application, the turn-on loss in the DC / DC converter can be reduced.

Description

[0001] This application is a divisional application. The original application has the application number 2021101842401 and the original application date is February 10, 2021. The entire contents of the original application are incorporated herein by reference. Technical Field

[0002] This application relates to the field of power supply technology, and in particular to a controller, power supply device and control system for an asymmetric half-bridge converter. Background Technology

[0003] A DC / DC converter (Direct-Current converter) includes transistors, inductors, and capacitors. By controlling the switching of the transistors, the inductors and capacitors are charged and discharged, thereby converting the input DC voltage into a set DC voltage. However, switching losses occur during the switching process; see [link to relevant documentation]. Figure 1 , Figure 1 This is a schematic diagram illustrating the voltage and current during the switching process of a switching transistor, provided in an embodiment of this application. Figure 1 As shown, during the turn-on process of the switching transistor, there is an overlap between the rise in switching current and the fall in switching voltage, resulting in turn-on losses. These turn-on losses can be understood as the power loss generated when the switching transistor goes from cutoff to conduction. Similarly, during the turn-off process of the switching transistor, there is also an overlap between the fall in switching current and the rise in switching voltage, resulting in turn-off losses. These turn-off losses can be understood as the power loss generated when the switching transistor goes from conduction to cutoff.

[0004] With the deepening of energy conservation efforts and the continuous improvement of power supply product efficiency, how to reduce the losses of switching transistors in DC / DC converters is a key research issue. Summary of the Invention

[0005] This application provides a controller, power supply device, and control system for a DC / DC converter, which can reduce losses in the DC / DC converter.

[0006] In a first aspect, embodiments of this application provide a controller for a DC / DC converter, wherein the controller is coupled to the DC / DC converter, which includes a first switching transistor, a second switching transistor, a first capacitor, and a transformer. The transformer includes a magnetizing inductance and a leakage inductance. The first and second switching transistors are connected in series and coupled across a DC power supply. The primary winding of the transformer is connected in parallel across the first switching transistor via the first capacitor. The secondary winding of the transformer is coupled to a DC load.

[0007] The controller controls the first switch to turn on, so that the first capacitor forms a first closed loop with the magnetizing inductor and the transformer leakage inductance through the first switch, and the current of the magnetizing inductor increases in the first direction.

[0008] After a preset time period, the controller controls the first switch to turn off, thereby reducing the voltage across the second switch.

[0009] When the voltage across the second switch is at a first preset voltage threshold, the controller controls the second switch to turn on, so that the DC power supply forms a second closed loop through the second switch, the first capacitor, the transformer leakage inductance, and the magnetizing inductor. At this time, the DC / DC converter enters a first state, and the current in the magnetizing inductor increases in a second direction, wherein the second direction is opposite to the first direction.

[0010] In this embodiment, before the DC / DC converter enters the first state, the first switch is turned on to provide a negative current to the second switch, thereby reducing the voltage across the second switch to a first preset voltage threshold. Implementing this embodiment can reduce the turn-on loss of the DC / DC converter.

[0011] In conjunction with the first aspect, in a first possible implementation, after the DC / DC converter enters the first state, the controller sends at least two pulse waves to the first switch and the second switch respectively according to a preset period, so that the DC / DC converter provides the target power to the DC load.

[0012] In this embodiment, the controller sends at least two pulse waves to the first and second switching transistors according to a preset cycle, thereby greatly improving the energy utilization efficiency of the DC / DC converter while reducing turn-on losses.

[0013] In conjunction with the first possible implementation of the first aspect, in the second possible implementation, the controller controls the first switch to turn on when the second switch is turned off between the switching of the DC / DC converter from the first state to the second state. At this time, the first capacitor, the transformer leakage inductance, the magnetizing inductance and the first switch form a third closed loop, and the current of the magnetizing inductance decreases along the second direction.

[0014] When the current in the excitation inductor decreases to a first preset current threshold, the controller controls the first switching transistor to turn off.

[0015] In this embodiment, by adding control over the first switch during the transition from the first state to the second state of the DC / DC converter, and after the second switch is turned off, i.e., controlling the first switch to turn on, the energy stored in the transformer leakage inductance can be transferred to the DC load, thereby improving energy utilization. Furthermore, by turning off the first switch only when the current of the magnetizing inductor decreases to a first preset current threshold, the oscillation of the voltage across the switch when the first switch is turned off can be reduced, thereby reducing the electromagnetic interference of the DC / DC converter.

[0016] In conjunction with the second possible implementation of the first aspect, in the third possible implementation, the second state is that both the first switch and the second switch are in the off state, and the parasitic capacitance of the first switch and the parasitic capacitance of the second switch form a resonant circuit with the first capacitor, the magnetizing inductor and the leakage inductance of the transformer.

[0017] In a fourth possible implementation, in combination with the first aspect or any of the above possible implementations of the first aspect, before the controller controls the first switch to turn on, the parasitic capacitance of the first switch and the parasitic capacitance of the second switch form a resonant circuit with the first capacitor, the excitation inductance and the leakage inductance of the transformer, and the voltage across the first switch is an oscillating voltage.

[0018] When the controller receives a signal that the DC / DC converter has entered the first state, it acquires the voltage across the first switch.

[0019] When the oscillation voltage across the first switching transistor is a second preset voltage threshold, the controller controls the first switching transistor to turn on.

[0020] In conjunction with the fourth possible implementation of the first aspect, in the fifth possible implementation, the aforementioned oscillation voltage includes voltages of each cycle, and the aforementioned second preset voltage threshold is the minimum voltage value among any cycle voltages.

[0021] In conjunction with the fourth possible implementation of the first aspect, in the sixth possible implementation, the signal for the DC / DC converter to enter the first state is determined based on the output voltage of the DC / DC converter.

[0022] In combination with the first aspect or any of the above possible implementations of the first aspect, in the seven possible implementations, the voltage across the second switch is reduced to the first preset voltage threshold after a first time period.

[0023] The current of the excitation inductor decreases from the target current to the second preset current threshold after the first time period. The target current is obtained by increasing the current of the excitation inductor after the preset time period.

[0024] In the eighth possible implementation, in combination with the first aspect or any of the above possible implementations of the first aspect, the first preset voltage threshold is zero.

[0025] In the ninth possible implementation, in combination with the first aspect or any of the above possible implementations of the first aspect, the first preset current threshold is zero.

[0026] Secondly, embodiments of this 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 a controller in the first aspect or any possible implementation of the first aspect, wherein the input terminal of the DC / DC converter is coupled to the DC power supply, the output terminal of the DC / DC converter is coupled to the DC load, and the control terminal of the DC / DC converter is coupled to the controller.

[0027] It should be understood that the implementations and beneficial effects of the above-mentioned aspects of this application can be referenced from each other. Attached Figure Description

[0028] Figure 1 A schematic diagram of voltage and current during the switching process of the switching transistor provided in an embodiment of this application;

[0029] Figure 2 A control system for a DC / DC converter provided in the embodiments of this application;

[0030] Figure 3 A circuit diagram of a DC / DC converter provided in an embodiment of this application;

[0031] Figure 4 A control timing diagram of a DC / DC converter provided in an embodiment of this application;

[0032] Figure 5 This is a partial equivalent circuit diagram of a DC / DC converter provided in an embodiment of this application;

[0033] Figure 6 A schematic diagram of the oscillation voltage provided in the embodiments of this application;

[0034] Figures 7A-7C These are further equivalent circuit diagrams of the DC / DC converters provided in the embodiments of this application;

[0035] Figure 8 This is another part of the equivalent circuit diagram of the DC / DC converter provided in the embodiments of this application;

[0036] Figure 9 Another circuit diagram of a DC / DC converter provided in an embodiment of this application. Detailed Implementation

[0037] The implementation of the technical solution of this application will be further described in detail below with reference to the accompanying drawings.

[0038] See Figure 2 , Figure 2 A control system for a DC / DC converter is provided as an embodiment of this application. For example... Figure 2 As shown, the input terminal of the DC / DC converter 202 is coupled to the DC power supply 201, the output terminal of the DC / DC converter 202 is coupled to the DC load 203, and the control terminal of the DC / DC converter 202 is coupled to the controller 204.

[0039] It should be noted first that the "coupling" described in this application refers to a direct or indirect connection. For example, the connection between A and B can be a direct connection between A and B, or an indirect connection between A and B through one or more other electrical components. For example, A can be directly connected to C, and C can be directly connected to B, thus achieving a connection between A and B through C.

[0040] The DC power supply 201 can be, for example, an energy storage battery (such as a nickel-cadmium battery, a nickel-metal hydride battery, a lithium-ion battery, a lithium polymer battery, etc.), a solar cell, an AC / DC converter (Alternating Current / Direct-Current converter) or other DC / DC converters (such as a BUCK converter, a BOOST converter, a BUCK-BOOST converter, etc.).

[0041] The DC / DC converter 202 in this application embodiment may include, but is not limited to, an asymmetric half-bridge flyback converter, an asymmetric half-bridge forward converter, etc.

[0042] The DC load 203 can be, for example, a mobile terminal, an energy storage battery, other DC / DC converters and / or DC / AC converters (Direct-Current / Alternating Current converters).

[0043] The controller 204 may be, for example, a central processing unit (CPU), other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc.

[0044] For example, the DC load 203 is a mobile terminal, the DC power supply 201 is an AC / DC converter that converts AC grid voltage to DC voltage, and the controller 204 can control the DC / DC converter 202 to convert the DC voltage output by the AC / DC converter to a set DC voltage value, such as 5V, 10V, etc. Exemplarily, the DC / DC converter 202 and the controller 204 can be located in a power adapter. The above are examples of usage scenarios for the DC / DC converter in this application embodiment, and not exhaustive. It should be understood that the controller in this application embodiment can control the DC / DC converter to be used in any scenario requiring DC voltage conversion.

[0045] See Figure 3 , Figure 3 A circuit diagram of a DC / DC converter provided in an embodiment of this application. Figure 3 As shown, the DC / DC converter includes a first switching transistor Q. L Second switch Q H First capacitor C r And a transformer, which includes a magnetizing inductance L m and transformer leakage inductance L r It is understandable that the magnetizing inductance, transformer leakage inductance, and ideal transformer can be concretely implemented as a single actual transformer. Furthermore, the DC / DC converter can also include a third switching transistor Q1, an output capacitor C0, and a load resistor R0, etc.

[0046] The embodiments of this application are illustrated by taking metal-oxide-semiconductor field-effect transistors (MOSFETs) as examples. It should be understood that each switching transistor can also be other semiconductor devices such as insulated-gate bipolar transistors (IGBTs).

[0047] First switching transistor Q L With the second switching transistor Q H After being connected in series, it is coupled to the DC power supply V. in The two ends of the first switching transistor Q L The drain of the second switch Q H Source coupling, second switch Q H Drain-coupled DC power supply V in The positive terminal, the first switch Q L Source-coupled DC power supply V in The negative terminal. Optional, DC power supply V in A filter capacitor C is connected in parallel across its two ends.in The primary winding of the transformer is connected to the first capacitor C. r Parallel connection to the first switching transistor Q L The two ends. For example, the first switch Q... L The drain coupling first capacitor C r One end, the first capacitor C r The other end is coupled to one side of the primary winding of the transformer, and the other side of the primary winding of the transformer is coupled to the first switching transistor Q. L The source of the transformer. The secondary side of the transformer is coupled to a DC load. For example, one side of the secondary side is coupled to the source of the third switching transistor Q1, the drain of the third switching transistor Q1 is coupled to one end of the output capacitor C0 and one end of the load resistor R0, and the other end of the output capacitor C0 and the other end of the load resistor R0 are coupled to the other side of the secondary side of the transformer. The output capacitor C0 can reduce the output voltage ripple of the DC / DC converter. For example, one side of the primary side of the transformer, for example, the upper side, and the other side of the secondary side of the transformer, for example, the lower side, are terminals of the same name, or the other side of the primary side of the transformer, for example, the lower side, and one side of the secondary side of the transformer, for example, the upper side, are terminals of the same name.

[0048] Understandable, Figure 3 In this embodiment, the load resistor R0 represents the DC load, and the DC load coupled to the DC / DC converter is not restricted. The third switch Q1 can be replaced by a diode to achieve the rectification function.

[0049] The individual switches in this DC / DC converter, such as the first switch Q... L Second switch Q H All of these are coupled to the controller (not shown in the figure). The controller can control the on / off state of each switch.

[0050] The timing sequence for the controller's on / off control of each switching transistor in the DC / DC converter can be found in [reference needed]. Figure 4 , Figure 4 This is a control timing diagram for a DC / DC converter provided in an embodiment of this application. Figure 4 As shown, V g (Q L ) is the controller sending to the first switch Q L The transmitted pulse waveform, V g (Q H ) for the controller to send to the second switch Q H The transmitted pulse waveform, V DS-QL The first switching transistor Q L The voltage waveform across the two ends, V DS-QH For the second switching transistor Q H Voltage waveform at both ends, I Lm For the magnetizing inductor L m The current waveform.

[0051] Before time t0, the first switch Q L Second switch Q H Both are in the off state. A partial equivalent circuit diagram of the DC / DC converter can be found in [reference needed]. Figure 5 .like Figure 5 As shown, the first switch Q L parasitic capacitance C L Second switch Q H parasitic capacitance C H With the first capacitor C r Magnetizing inductance L m and transformer leakage inductance L r A resonant circuit is formed. Optionally, after the resonant circuit reaches resonance stability, the first switch Q... L The voltage across the terminals can be a stable resonant value, for example, the voltage across the first capacitor C. r The voltage values ​​at both ends.

[0052] In some feasible implementations, when the controller receives a signal that the DC / DC converter has entered the first state, it acquires the first switch Q. L The voltage at both ends. For example, a voltage sensor is coupled to the output terminal of the DC / DC converter. This voltage sensor generates a signal indicating that the DC / DC converter has entered a first state when the output voltage of the DC / DC converter is lower than a third preset voltage threshold, and sends this signal to the controller. Alternatively, a DC load coupled to the secondary side of the transformer can monitor the output voltage of the DC / DC converter in real time. For example, this DC load is an energy storage battery equipped with a voltage monitoring function. The battery monitors the output voltage of the DC / DC converter in real time, and when the output voltage of the DC / DC converter decreases to a fourth preset voltage threshold within a preset time range, it generates a signal indicating that the DC / DC converter has entered a first state, and sends this signal to the controller. This application does not limit how the signal indicating that the DC / DC converter has entered a first state is generated. Optionally, the aforementioned third preset voltage threshold and / or the aforementioned fourth preset voltage threshold can be predetermined based on the DC load.

[0053] First switch Q L When the oscillation voltage across the terminals is the second preset voltage threshold, the first switch Q is switched. L Send a high level (i.e., control the first switching transistor Q) L (Open).

[0054] In some feasible implementations, the aforementioned oscillation voltage includes individual periodic voltages, see [link to relevant documentation]. Figure 6 , Figure 6 This is a schematic diagram of the oscillation voltage provided in an embodiment of this application. For example... Figure 6As shown, each voltage cycle contains a minimum voltage value corresponding to that cycle. Figure 6 The voltage values ​​corresponding to points a, b, and c are shown in the diagram. The aforementioned second preset voltage threshold can be the minimum voltage value in any cycle. For example, when the controller receives a signal that the DC / DC converter has entered the first state, the controller can monitor the first switching transistor Q in real time. L The voltage across the terminals determines the first switching transistor Q. L The voltage across the terminals is the minimum value of the voltage in that cycle; for example, the controller detects the first switching transistor Q. L When the voltage across the terminals is the target voltage value, after the target time period, the first switching transistor Q... L When the voltage across the terminals drops to the minimum voltage value of the current cycle, the controller controls the first switching transistor Q. L The activation timeframe is related to the aforementioned resonant circuit. This occurs during the first switching transistor Q. L When the voltage across the terminals is the minimum voltage value in any cycle, the first switch Q is controlled. L Turn on, first switch Q L The activation loss is relatively small.

[0055] At time t0, the controller's first switching transistor Q L After activation, during times t0 to t1, the first capacitor C r After the first switching transistor Q L With excitation inductance L m and transformer leakage inductance L r To form the first closed loop, a partial equivalent circuit diagram of the DC / DC converter can be found in [reference needed]. Figure 7A .like Figure 7A As shown, the magnetizing inductance L m The current increases along the first direction, i.e., the magnetizing inductance L m The current increases counterclockwise. In this embodiment, clockwise is taken as the positive direction, combined with... Figure 4 The excitation inductor L shown in the figure m Current waveform I Lm It can be seen that the magnetizing inductance L m The current increases in the negative direction. In some feasible implementations, the magnetizing inductance L... m The counterclockwise increase in current can be caused by the reflected voltage from the secondary side of the transformer (not shown in the figure) applied to the magnetizing inductor L. m This is caused by both ends.

[0056] Understandably, due to system detection errors and / or system control errors, the first switching transistor Q... L The activation time was not accurate enough; the excitation inductor L m If the oscillating current at t0 is in the positive direction, then the magnetizing inductance Lm The current undergoes a change in direction between time t0 and t1, that is, it decreases to zero in the positive direction and then increases in the negative direction.

[0057] In some feasible implementations, the time period from t0 to t1 (i.e., the preset time period) can be a pre-calculated fixed value, for example, it can be based on the first capacitor C. r First switching transistor Q L parasitic capacitance C L Second switch Q H parasitic capacitance C H Magnetizing inductance L m and transformer leakage inductance L r The results were obtained through calculation.

[0058] At time t1, the controller controls the first switch Q. L Turn off. Since the inductor current cannot change abruptly, in the first switching transistor Q... L After shutdown, a partial equivalent circuit diagram of the DC / DC converter can be found in [reference needed]. Figure 7B .like Figure 7B As shown, the transformer leakage inductance L r And excitation inductance L m To the first switching transistor Q L parasitic capacitance C L Charging, to the second switch Q H parasitic capacitance C H Discharge.

[0059] From time t1 to t2, the first switch Q L Voltage V across the terminals DS-QL Increase, second switch Q H Voltage V across the terminals DS-QH Reduced. In some feasible implementations, during the time period from t0 to t1 (i.e., a preset time period), the magnetizing inductance L... m The current can be increased to the target current in the first direction (i.e., counterclockwise). During the time interval t1 to t2, the magnetizing inductance L m The current can decrease from the target current in a clockwise direction over a first time period to a second preset current threshold. At this time, the second switch Q... H Voltage V across the terminals DS-QH After the same amount of time (i.e., the first time period), the voltage decreases to a first preset voltage threshold, and this first time period is no greater than the time period from t1 to t2. For example, the DC / DC converter in this embodiment of the application periodically switches from the second state to the first state. A reference time period can be preset as the current cycle's preset time period. Within this preset time period, if the magnetizing inductance L... mWhen the current decreases clockwise to the second preset current threshold, the second switch Q... H Voltage V across the terminals DS-QH If the voltage has decreased to the first preset threshold, then the preset time period for the next cycle will be reduced based on the preset time period of the current cycle; if the magnetizing inductance L m When the current decreases clockwise to the second preset current threshold, the second switch Q... H Voltage V across the terminals DS-QH If the voltage does not decrease to the first preset threshold, the preset time period for the next cycle is increased based on the preset time period of the current cycle. In other words, the second switch Q... H Voltage V across the terminals DS-QH The time it takes for the voltage to decrease to the first preset threshold and the excitation inductance L m The time it takes for the current to decrease clockwise to the second preset current threshold is equal to or close to that of the current. Taking a first preset voltage threshold of zero and a second preset current threshold of zero as an example, this can be understood as the excitation inductance L... m When the energy on the circuit is just completely released, the second switch Q... H parasitic diode D H It conducts electricity, improving energy utilization efficiency.

[0060] At time t2, the controller sends a signal to the second switch Q. H Send a high-level signal (i.e., control the second switch Q) H (Turn on), at this time the second switch Q H Voltage V across the terminals DS-QH The first preset voltage threshold is set.

[0061] Between times t2 and t3, the second switch Q H When in the ON state, a partial equivalent circuit diagram of the DC / DC converter can be found in [reference needed]. Figure 7C .like Figure 7C As shown, DC power supply V in After the second switching transistor Q H First capacitor C r Transformer leakage inductance L r and excitation inductance L m A second closed loop is formed, at which point the DC / DC converter enters the first state, and the magnetizing inductor L... m The current increases in a second direction, which is opposite to the first direction. In other words, the second direction is clockwise (i.e., the positive direction).

[0062] In this embodiment of the application, before the DC / DC converter enters the first state, the first switch is turned on to provide a negative current to the second switch, thereby reducing the voltage across the second switch to a first preset voltage threshold. Implementing this embodiment of the application can reduce the turn-on loss of the DC / DC converter.

[0063] For example, with Figure 4 The diagram illustrates an example where the first preset voltage threshold is zero. During times t1 to t2, the second switch Q... H Voltage V across the terminals DS-QH Reduced to zero, the first switch Q L Voltage V across the terminals DS-QL Increase accordingly to DC power supply V in The voltage value of the second switch Q during the time interval from t1 to t2. H parasitic capacitance C H From the start of discharge to the end of discharge. Second switch Q H parasitic diode D H In the parasitic capacitance C H After the discharge ends (i.e., at time t2), the second switch transistor 1 is turned on, causing it to conduct. H Voltage V across the terminals DS-QH Reduced to zero. In this embodiment, the controller is in the second switch Q... H Voltage V across the terminals DS-QH When the value decreases to zero, the second switch Q is controlled. H Turn on, second switch Q H Zero-voltage turn-on is achieved, which can reduce the turn-on losses of DC / DC converters.

[0064] Furthermore, after the DC / DC converter enters the first state, the controller sends signals to the first switching transistor Q according to a preset cycle. L Second switch Q H Send at least two pulse waves. In specific implementations, this can be combined with... Figure 4 As shown in the diagram, from time t2 to t8, after the DC / DC converter enters the first state at time t2, the controller sends signals to the first switching transistor Q according to a preset cycle. L Second switch Q H Taking the transmission of two pulse waves as an example, the first switching transistor Q is alternately controlled between times t2 and t7. L Second switch Q H Turning on to provide target power to a DC load, for example, controlling the second switch Q at times t2 to t3. H Turn on; control the first switching transistor Q from time t4 to t5. L Turn on; control the second switch Q from time t6 to t7. H Activated. T3 to T4 and T5 to T6 are dead time zones.

[0065] In this embodiment, the controller sends at least two pulse waves to the first and second switching transistors according to a preset cycle, thereby greatly improving the energy utilization efficiency of the DC / DC converter while reducing turn-on losses.

[0066] Furthermore, during the transition of the DC / DC converter from the first state to the second state, when the second switch Q... H After being turned off, control the first switch Q. L When the circuit is turned on, the first capacitor C... r Transformer leakage inductance L r Magnetizing inductance L m and the first switching transistor Q L To form a third closed loop, a partial equivalent circuit diagram of the DC / DC converter can be found in [reference needed]. Figure 8 Magnetizing inductance L m Energy in the first capacitor C r Transmission causes the magnetizing inductance L m The current decreases along the second direction, i.e., the magnetizing inductance L m The current decreases in a clockwise direction. In some feasible implementations, the magnetizing inductance L m The decrease in current in the clockwise direction can be due to the reflected voltage from the secondary side of the transformer (not shown in the figure) applied to the magnetizing inductor L. m This is caused by both ends. (Combination) Figure 4 Let me explain the specific implementation. Figure 4 Taking the DC / DC converter receiving three pulse waves in the first state as an example, after the controller sends out the three pulse waves, it controls the second switch Q. H After being turned off, control the first switch Q. L Turn-on. It can be understood that the DC / DC converter is in the first state from time t2 to t7, and in the second state after time t9. The transition from the first to the second state can be understood as the time interval between t7 and t9. When the second switching transistor Q... H After being turned off, after a dead time (i.e., t7 to t8), the first switch Q is controlled at time t8. L Turn on, excitation inductor L m The current decreases in a clockwise direction.

[0067] In some feasible implementations, the switching from the first state to the second state of the DC / DC converter can be pre-set by the controller, that is, the number of pulse waves sent by the controller to the DC / DC converter can be pre-set. Optionally, the switching from the first state to the second state of the DC / DC converter can also be determined according to the state of the DC load, such as the current, voltage and / or power of the DC load.

[0068] In the magnetizing inductor L m When the current is equal to the first preset current threshold, control the first switching transistor Q. L Turn off to allow the DC / DC converter to enter the second state.

[0069] In this embodiment, by adding control over the first switch during the transition from the first state to the second state of the DC / DC converter, and after the second switch is turned off, i.e., controlling the first switch to turn on, the energy stored in the transformer leakage inductance can be transferred to the DC load, thereby improving energy utilization; and in the magnetizing inductor L m The first switch is turned off only when the current reaches the first preset current threshold, which can reduce the oscillation of the voltage across the switch when the first switch is turned off and reduce the electromagnetic interference of the DC / DC converter.

[0070] Optionally, in some feasible implementations, with Figure 4 The diagram shows an example where the first preset current threshold is zero, and the magnetizing inductance L... m When the current decreases to zero, the controller controls the first switching transistor Q. L When the first switch Q is turned off, L Zero-current shutdown can be achieved. For example, the controller can obtain the excitation inductance L in real time. m The current is used to determine the magnetizing inductance L. m The current is reduced to zero; for example, the controller can also calculate the magnetizing inductance L based on the resonant state and circuit parameters of the DC / DC converter. m The target time for the current to decrease to zero. This application's embodiments do not specify how to determine the excitation inductance L. m The current is reduced to a first preset current threshold for limitation.

[0071] See Figure 9 , Figure 9 Another circuit diagram of a DC / DC converter provided in an embodiment of this application. (See diagram below.) Figure 9 As shown, the DC / DC converter includes a first switching transistor Q. H1 Second switch Q L1 First capacitor C r1 And a transformer, which includes a magnetizing inductance L m1 and transformer leakage inductance L r1Furthermore, the DC / DC converter may also include a third switch Q2 and an output capacitor C. 01 and load resistance R 01 wait.

[0072] This DC / DC converter is similar to the one mentioned above. Figure 3 The difference in the DC / DC converter shown is that the positions of the first and second switching transistors are interchanged.

[0073] First switching transistor Q H1 The source of the second switch Q L1 The drain coupling, the first switch Q H1 Drain-coupled DC power supply V in1 The positive terminal, the second switch Q L1 Source-coupled DC power supply V in1 The negative terminal. Optional, DC power supply V in1 A filter capacitor C is connected in parallel across its two ends. in1 The primary winding of the transformer is connected to the first capacitor C. r1 Parallel connection to the first switching transistor Q H1 The two ends. For example, the first switch Q... H1 The drain coupling first capacitor C r1 One end, the first capacitor C r1 The other end is coupled to one side of the primary winding of the transformer, and the other side of the primary winding of the transformer is coupled to the first switching transistor Q. H1 The source of the transformer. The secondary side of the transformer is coupled to a DC load; for example, one side of the transformer secondary side is coupled to the source of the third switch Q2, and the drain of the third switch Q2 is coupled to the output capacitor C. 01 one end and load resistor R 01 One end, output capacitor C 01 The other end and the load resistor R 01 The other end is coupled to the other side of the transformer secondary winding, and the output capacitor C 01 This can reduce the output voltage ripple of the DC / DC converter. For example, 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 terminals of the same name, or the other side of the primary side of the transformer, such as the lower side, and one side of the secondary side of the transformer, such as the upper side, are terminals of the same name.

[0074] In the specific implementation Figure 9 The DC / DC converter shown can also be used Figure 4 The control timing diagram shown in the figure only shows V g (Q L ) changed to the controller directing the first switching transistor Q H1 The transmitted pulse waveform, V g (Q H ) changed to controller to the second switch QL1 The transmitted pulse waveform. The equivalent circuit of this DC / DC converter at different times can be found in the preceding text. Figures 5 to 8 The described embodiments are not elaborated here.

[0075] Understandable, Figure 9 The DC / DC converter shown can achieve the combination of the above. Figures 3 to 8 Any of the possible implementations described can also achieve the above-mentioned beneficial effects.

[0076] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0077] In the various embodiments of the present invention, all functional units can be integrated into one processing unit, or each unit can be a separate unit, or two or more units can be integrated into one unit; the integrated unit can be implemented in hardware or in the form of hardware plus software functional units.

[0078] If the integrated units of this invention are implemented as software functional modules and sold or used as independent products, they can also be stored in a computer-readable storage medium. Based on this understanding, the technical solutions of the embodiments of this invention, or the parts that contribute to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the methods described in the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as mobile storage devices, ROM, RAM, magnetic disks, or optical disks.

[0079] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A power supply device characterized by comprising: The power supply device comprises an asymmetric half-bridge converter and a controller, the asymmetric half-bridge converter comprises a first switch tube, a second switch tube, a first capacitor and a transformer, the transformer comprises an excitation inductance and a transformer leakage inductance, the first switch tube and the second switch tube are coupled in series and then coupled across a DC power supply, a primary side of the transformer is connected in parallel to the first switch tube through the first capacitor, and a secondary side of the transformer is coupled with a DC load, wherein The controller is configured to: control the first switch tube to be turned on for a preset time period before alternately controlling the first switch tube and the second switch tube to be turned on, so that the first capacitor forms a first closed loop with the excitation inductance of the transformer and the leakage inductance of the transformer through the first switch tube, and the current of the excitation inductance increases in a first direction; after the first switch tube is turned off, control the second switch tube to be turned on according to a comparison result of a voltage across the second switch tube and a first preset voltage threshold, so that the second switch tube, the first capacitor, the leakage inductance of the transformer and the excitation inductance of the transformer form a second closed loop, and the current of the excitation inductance increases in a second direction opposite to the first direction.

2. The power supply device according to claim 1, characterized by Before alternately controlling the first switch tube and the second switch tube to be turned on, the parasitic capacitance of the first switch tube and the parasitic capacitance of the second switch tube form a resonance loop with the first capacitor, the excitation inductance of the transformer and the leakage inductance of the transformer; The controller is configured to control the first switch tube to be turned on when the oscillation voltage across the first switch tube is at a minimum.

3. A controller for an asymmetrical half-bridge converter, characterized by The asymmetric half-bridge converter comprises a first switch tube and a second switch tube, the first switch tube and the second switch tube are coupled in series and then coupled across a DC power supply, the first switch tube is connected in parallel to a primary side of a transformer through a first capacitor, a secondary side of the transformer is coupled with a DC load, the transformer comprises an excitation inductance and a transformer leakage inductance, and the controller is configured to: control the first switch tube to be turned on for a preset time period before alternately controlling the first switch tube and the second switch tube to be turned on; after the first switch tube is turned off, control the second switch tube to be turned on according to a comparison result of a voltage across the second switch tube and a first preset voltage threshold.

4. The controller of claim 3, wherein, The controller is configured to control the first switch tube to be turned on when the voltage across the first switch tube is at a second preset voltage threshold before alternately controlling the first switch tube and the second switch tube to be turned on.

5. The controller of any one of claims 3-4, wherein, The controller is configured to control the first switch tube to be turned on when the oscillation voltage across the first switch tube is at a minimum before alternately controlling the first switch tube and the second switch tube to be turned on, and the asymmetric half-bridge converter is in a resonance state.

6. A power supply device characterized by comprising: comprises An asymmetric half-bridge converter, comprising a first switch and a second switch, the first switch and the second switch are coupled in series and then coupled across a DC power source, the first switch is coupled in parallel to a primary of a transformer through a first capacitor, a secondary of the transformer is coupled to a DC load, the transformer comprises a magnetizing inductance and a transformer leakage inductance; a controller for alternately controlling the first switch and the second switch to be turned on; wherein, before alternately controlling the first switch and the second switch to be turned on, the controller controls the first switch to be turned on for a preset time period; after the first switch is turned off, the controller controls the second switch to be turned on according to a comparison result of a voltage across the second switch and a first preset voltage threshold.

7. The power supply device according to claim 6, wherein Before alternately controlling the first switch and the second switch to be turned on, the controller controls the first switch to be turned on for a preset time period, specifically comprising: When the voltage across the first switch is a second preset voltage threshold, the controller controls the first switch to be turned on before alternately controlling the first switch and the second switch to be turned on.

8. The power supply device according to claim 7, characterized by During the process that the controller controls the first switch to be turned on for the preset time period, the first capacitor forms a first closed loop with the magnetizing inductance of the transformer and the leakage inductance of the transformer through the first switch, and the current of the magnetizing inductance increases in a first direction.

9. The power supply device according to claim 8, characterized by During the process that the controller controls the second switch to be turned on, the DC power source forms a second closed loop with the leakage inductance of the transformer and the magnetizing inductance of the transformer through the second switch and the first capacitor, and the current of the magnetizing inductance increases in a second direction, wherein the second direction is opposite to the first direction.

10. The power supply device according to any one of claims 6 to 9, characterized by Before alternately controlling the first switch and the second switch to be turned on, the asymmetric half-bridge converter is in a resonant state, and the first switch is controlled to be turned on when the oscillation voltage across the first switch is the lowest.

11. A control system for a DC / DC converter, characterized by The control system comprises the power supply device of any one of claims 1-2, the controller of any one of claims 3-5, or the power supply device of any one of claims 6-10.

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