CN111404359B - Primary side current sampling system of active clamping flyback converter - Google Patents
Primary side current sampling system of active clamping flyback converter Download PDFInfo
- Publication number
- CN111404359B CN111404359B CN202010324535.XA CN202010324535A CN111404359B CN 111404359 B CN111404359 B CN 111404359B CN 202010324535 A CN202010324535 A CN 202010324535A CN 111404359 B CN111404359 B CN 111404359B
- Authority
- CN
- China
- Prior art keywords
- sampling
- signal
- circuit
- primary side
- input
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Classifications
-
- 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
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/0003—Details of control, feedback or regulation circuits
- H02M1/0009—Devices or circuits for detecting current in a converter
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/0003—Details of control, feedback or regulation circuits
- H02M1/0012—Control circuits using digital or numerical techniques
-
- 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
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Dc-Dc Converters (AREA)
Abstract
The invention discloses a low-loss primary side current sampling system of an active clamping flyback converter, which comprises a primary side current sampling circuit and a control method, wherein the primary side current sampling circuit comprises an input stage, a sampling control circuit and a sampling holding circuit, and the primary side current sampling circuit comprises three parts: the input stage utilizes the auxiliary transformer to establish an input signal of the sampling control circuit, the sampling control circuit is responsible for controlling the working state of the sampling hold circuit according to the signal established by the input stage, and the sampling hold circuit is responsible for sampling operation. The invention is suitable for most active clamping flyback converters, and the primary side current signal of the main power transformer is sampled by utilizing a digital logic circuit, a plurality of discrete devices and an auxiliary transformer, so that the sampled signal can be kept for a period of time. Meanwhile, the invention simplifies the circuit structure and the control strategy of primary side current sampling under the precondition of ensuring higher sampling precision, does not cause excessive extra power consumption, saves area and reduces circuit cost.
Description
Technical Field
The invention relates to a primary side sampling system of an isolated power converter, in particular to a primary side current sampling circuit of an active clamping flyback converter and a control strategy thereof.
Background
Flyback-type converters are one of the commonly employed topologies in low power converter applications. The active clamping flyback converter is used as a flyback converter, has the advantages that leakage inductance energy can be used for realizing soft switching or output, the duty ratio can be larger than 0.5, the working frequency and the efficiency can be higher, and the like, and is gradually paid attention to. This gives a good solution for a low power converter to increase power density, switching frequency and operating efficiency. In addition, the synchronous rectifying tube is adopted to replace a diode at the secondary side of the active clamping flyback converter, so that the conduction loss problem caused by the diode at the secondary side is reduced, and the working efficiency of the converter can be improved greatly. Flyback topology for active clamp and its derivativeA common control strategy is to supply the primary winding current I to the main power transformer p When the power supply is in the range of (0), the synchronous rectifying tube on the secondary side is started to transmit energy so as to enable the switching tube to realize zero-voltage switching (Zero Voltage Switch, ZVS) to reduce loss and improve working efficiency; if primary current I of main power transformer p >When the synchronous rectifying tube is started at 0 time, the starting time of the lower period is required to be delayed, if the primary side current I of the main power transformer p When=0, the synchronous rectifier is not yet turned on, and the turn-on time of the next period can be advanced. In order to implement the control strategy, it is necessary to provide a primary current sampling circuit and a matched signal processing circuit for the primary current of the main power transformer. The primary side current of the main power transformer belongs to a part of the power loop signal, cannot be directly sampled and needs to be subjected to certain treatment: the primary side current is converted into the input of analog control through means such as comparison and amplification, or the primary side current is converted into the input of a digital control circuit through conversion. This requires that the sampling circuit is capable of withstanding the high voltage and high current of the power loop and has little or no impact on the main topology under conditions that can achieve a certain accuracy. Meanwhile, factors such as a cloth plate, wiring, occupied area and heat generation are considered. Therefore, careful consideration is required to implement a sampling strategy and sampling circuit to implement a small, low cost power converter.
The current sampling circuits of the prior common primary side can be basically classified into two types: leading out branches at the primary side or the secondary side of the main power transformer for direct sampling, and calculating the primary side current of the main power transformer according to the turn ratio and other parameters; secondly, an auxiliary winding is arranged on the main power transformer part, current signals on the auxiliary winding are sampled, deducing calculation is carried out according to parameters such as turn ratio and the like, and therefore primary side current of the main power transformer is obtained. For the sampling mode of the direct extraction branch, the current on the extraction branch is not suitable for direct sampling of the digital control part, and an analog control strategy is needed to be adopted or converted into a digital signal. The design of the analog control strategy is complex, the analog control strategy is sensitive to noise, and the occupied area is larger than that of digital control; the conversion circuit is added to occupy a larger area. In addition, since the sampling circuit in the mode is directly connected with the main power transformer, the control strategy design also needs to consider the tolerance capability of the sampling control circuit to high voltage and large current and the influence on the main power transformer, and the problems of larger power consumption and lower sampling precision exist. Due to the problems of complex design, high cost and the like, the sampling strategy of the direct leading-out branch is relatively less in practical production and application. For the sampling strategy of setting the auxiliary winding, considering the PCB planar transformer, adding the auxiliary winding necessarily increases the number of layers of the PCB, and increases the complexity of the design of the main power transformer. The sampling accuracy of this sampling strategy is largely dependent on the accuracy of the conversion circuit, which occupies a large area. Meanwhile, no matter how reasonable the parameter design of the main power transformer is, the auxiliary winding can bring certain loss, which is not beneficial to realizing the small-area low-cost switching power supply converter.
Disclosure of Invention
The technical problems to be solved by the invention are as follows: the primary side current sampling circuit and the corresponding control strategy are provided by using the working characteristics of the active clamping flyback converter to realize the primary side current sampling of the main power transformer, and the primary side current sampling circuit and the corresponding control strategy can realize the primary side current sampling of the main power transformer with smaller area, lower loss and simpler control under the condition of generating smaller influence on the main power topology, especially the main power transformer, so that the purposes of reducing area and cost, simplifying circuits and controlling and reducing power consumption are achieved on the premise of ensuring the sampling precision.
The invention adopts the following technical scheme for solving the technical problems: the sampling system comprises a primary side current sampling circuit, wherein the primary side current sampling circuit comprises an input stage, a sampling control circuit and a sampling hold circuit, the output end of the input stage is connected with the reset end of an RS trigger in the sampling control circuit, and the sampling pulse output end of the sampling control circuit is connected with the control end of a sampling switch in the sampling hold circuit.
As an improvement of the present invention, the input stage includes an inputFilter capacitor C 1 Auxiliary transformer T 1 Filter capacitor C 2 Resistance R 1 Clamping diode D 1 . For said input filter capacitor C 1 Filter capacitor C 2 And clamping diode D 1 C because the main power signal is not processed at the input stage circuit 1 、C 2 And D 1 High pressure may not be sustained and therefore volume is a priority. Specifically, for C 1 And C 2 The patch capacitor with larger capacitance value should be selected, and the specific capacitance value should be determined according to the working condition of the main power loop, so that good filtering effect can be achieved; for D 1 The patch diode with higher switching speed should be selected, specific parameters should be determined according to the working conditions of the main power loop and the auxiliary transformer, and the voltage at the diode can be clamped at a certain fixed value for a period of time, so that the post-stage digital circuit can work normally. For said auxiliary transformer T 1 The side close to the input signal is regarded as a primary side, the side close to the sampling control circuit is regarded as a secondary side, and the converter is buried in the PCB of the converter. The input stage is capable of establishing an input signal of the sampling control circuit using an auxiliary transformer. The input signal required by the input stage is connected with the input filter capacitor C 1 And auxiliary transformer T 1 Auxiliary transformer T between one ends of primary windings 1 The other end of the primary winding is provided with a filter capacitor C 1 The other end of the two parts is connected; one end of secondary winding of auxiliary transformer is connected with C 2 The other end is simultaneously connected with R 1 And clamping diode D 1 Positive electrode of D 1 Negative electrode of (A) and R 1 、C 2 And the sampling control circuits are connected and connected.
As an improvement of the invention, the sampling control circuit can control the working state of the sampling hold circuit according to the signal established by the input stage, and the sampling control circuit comprises an RS trigger and a delay unit B 1 Inverter I 1 Two-input OR gate 1 Two-input AND gate AND 1 Output inverter I 2 The reset end of the RS trigger is used as the input end of the sampling control circuit, and the Q end of the RS trigger is connected with the inverter I at the same time 1 Delay unit B 1 OR OR AND gate 1 Inverter I 1 The output of (1) is connected with AND gate AND 1 Delay unit B 1 Output simultaneous OR gate of (C) 1 AND gate AND 1 OR gate OR 1 The output of (a) is connected with an inverter I 2 Inverter I 2 The output of (a) is used as the output end of the sampling control circuit, AND AND gate 1 As output of the sampling pulse.
As an improvement of the invention, the sample-and-hold circuit can sample the primary current signal of the main power transformer and can hold the sampled signal for a period of time. The sample-and-hold circuit comprises a sampling switch S 1 Sampling resistor R 2 Ground resistance R 3 Holding capacitor C 3 The signal input end of the sample hold circuit is connected with the sampling resistor R 2 Sampling resistor R 2 S is connected with 1 One end of the switch and R 3 ，S 1 The other end of the switch is connected with a holding capacitor C 3 And simultaneously as a signal output end, R 3 And C 3 The other end is grounded, sampling switch S 1 The control end of the (C) is connected with the sampling pulse output end of the sampling control circuit.
As an improvement of the invention, the auxiliary transformer T 1 The air is used as a magnetic core to transmit the synchronous rectifying tube switching signal of the secondary side of the converter, and energy transmission is basically not performed. Air is used as a magnetic core, holes or grooves are not required to be drilled on the PCB, the size is small, the structure is simple, the auxiliary transformer can be buried in the whole PCB, and the surface area is not occupied. The auxiliary transformer is arranged on the windings of the first layer, the second layer, the third layer and the fourth layer of PCB, the windings of the second layer and the third layer are primary sides, and the windings of the two layers pass through the through holes P 2 Series connection of P 1 And P 3 Respectively connect V to two ends of primary winding in Positive and negative ends of the signal; the windings of the first layer and the fourth layer are secondary sides and are mutually connected in parallel, and the through holes S 1 、S 2 For both ends of the first layer S 3 、S 4 Two ends of the fourth layer are respectively connected to the reset end of the RS trigger through the positive poles of the filter capacitor and the clamping diode; the whole auxiliary transformer is of a sandwich structure, and takes air as a magnetic core.
As an improvement of the invention, the sampling resistor R 2 The resistance is smaller, and can be set to 0.5-2k omega or even smaller according to the actual requirement of the circuit, so that the resistance of the whole circuit is smaller when a sampling switch is started, and higher sampling precision is further ensured; ground resistance R 3 The resistance is larger, and can be set to 10-30kΩ or even larger according to the actual requirement of the circuit, so as to ensure that the resistance of the whole circuit is large when the sampling switch is turned off, thereby ensuring that no great power consumption exists.
A control method of a low-loss primary side current sampling system of an active clamping flyback converter comprises the following steps: the control method uses the synchronous rectifying tube switch signal of the secondary side of the converter as input, and generates sampling pulse of ten nanoseconds by using the structure and the characteristics of the circuit, and then drives a switch in the sampling hold circuit by using the sampling pulse to control the sampling hold circuit to sample; the input stage uses auxiliary transformer to realize electric isolation and voltage conversion, uses clamping diode to make signal keep, so as to establish reset signal which can be adapted to post-stage digital circuit, uses converter secondary synchronous rectifier switching signal as input signal, and uses conversion of auxiliary transformer and retention of clamping diode to transfer signal to reset end of RS trigger in sampling control circuit, the sampling control circuit is digital circuit, and can utilize basic properties of circuit itself, etc., according to the signal established by input stage to control working state of sampling and holding circuit, the RS uses output signal of input stage as reset signal, and the complementary signal of the generated output signal and output signal (by inverter I) 1 Signals implementing reverse complements) are commonly input to AND gate AND 1 OR OR AND gate 1 AND gate AND 1 Generating a sampling pulse signal for controlling the sample-hold switch due to the delay unit B 1 Is present, AND after a certain period of time (about 20-35 ns) 1 The resulting sampling pulse signal becomes inactive, OR gate 1 Generates an output signal which is passed through an inverter I 2 After the current is input to the primary side of the converter, the primary side of the main power transformer is guaranteed to be conducted, and the sampling and holding circuit can sample the primary side current signal of the main power transformerThe sampling circuit takes the primary side current signal of the main power transformer as direct input and passes through a sampling resistor R 2 Converts the current signal into a voltage signal and passes through a sampling switch S 1 Transmitting to the output end of the sample hold circuit to obtain the required sampling signal, when the sampling switch S 1 When the circuit is started, sampling is carried out, and the output end of the sampling hold circuit outputs a signal obtained by sampling; when sampling switch S 1 When closed, due to the holding capacitance C 3 The signal at the output end of the sample-and-hold circuit is kept for a period of time, and the holding time and the holding capacitance C 3 Related to the parameters of (a).
As an improvement of the invention, the input stage generates output according to the on-off condition of the synchronous rectifying tube of the secondary side of the converter, and the output can reset the RS trigger of the sampling control circuit; the output signal of the RS trigger is delayed by the built-in delay unit, so that sampling pulses of tens of nanoseconds can be generated at the output end of the AND gate; the sampling pulse controls the on-off of a sampling switch in the sampling hold circuit so as to realize the sampling of primary side current of the main power transformer; and generating an output signal at the output end of the OR gate and feeding the output signal back to the primary side of the converter so as to ensure that the primary side of the main power transformer is in a conducting state in the whole sampling period.
As an improvement of the invention, the control circuit sets different on-off states for the switch of the sample hold circuit at different moments according to the working state of the synchronous rectifying tube of the secondary side of the converter, and the invention is as follows: in each converter period, when the secondary synchronous rectifier tube is conducted instantaneously, sampling pulse is effective, the effective duration is the delay of a delay unit in a sampling control circuit, the sampling switch is conducted generally within 20-35ns, and a sampling hold circuit samples primary side current; the rest time, sampling pulse is invalid, and the sampling and holding circuit holds the obtained signal
Compared with the prior art, the technical scheme provided by the invention has the following technical effects: 1) According to the technical scheme, sampling is immediately carried out after the secondary synchronous rectifying tube is started, a sampling hold circuit connected with a primary winding of a main power transformer is controlled to be started by utilizing short pulses, and sampling is completed, and as an auxiliary winding of the main power transformer is not utilized, the area and the cost are effectively saved; the short pulse duration is negligible relative to the working period of the converter, and the sampling hold circuit is considered to be in an open circuit state for most of the time, so that the influence on the main power transformer is negligible; 2) The number of the sampling hold circuit devices is small, and the design is simple. The sampling hold circuit is started after the secondary synchronous rectifying tube, so that the current in the main power transformer is close to 0, and the load of the sampling switch is small; 3) The starting time of the sampling hold circuit is very short, so that the resistance value of the sampling resistor is very small without generating larger power consumption, and higher sampling precision is obtained; 4) The control strategy in the scheme is realized by a pure digital circuit, has a simpler structure, can be realized by a small integrated circuit, is insensitive to noise, is easy to package, is beneficial to saving the area, and is safe and reliable; 5) In the scheme, the auxiliary transformer adopts an air magnetic core, so that the board is convenient to distribute and the area is saved. The auxiliary transformer is used for transmitting the secondary synchronous rectifier grid signal and is not connected into the main power loop, so that even if an air magnetic core is adopted, the loss of the auxiliary transformer is still small relative to that of the main power transformer, and the air magnetic core has better response speed and shorter delay, thereby being beneficial to faster establishment of control pulses of the sampling switch. Meanwhile, the air magnetic core is adopted, the occupied PCB layers are fewer, the air magnetic core can be placed in the PCB, the surface space is not occupied, the number of PCB layers is not increased, the area is reduced, the cost is saved, and meanwhile, the air magnetic core has the advantages of flexible board distribution, small influence from the outside and the like.
Drawings
FIG. 1 is a schematic diagram of an exemplary primary current sampling circuit;
FIG. 2 is a PCB layout of an enumerated primary current sampling circuit input stage auxiliary transformer and its various layers of windings;
FIG. 3 is a schematic diagram of a layout of an auxiliary transformer across the transformer;
FIG. 4 is a schematic diagram of the signal paths of an exemplary primary current sampling circuit;
FIG. 5 is a control strategy flow chart for an enumerated control strategy over a cycle;
FIG. 6 is a waveform diagram of a sampling control circuit generating sampling pulses;
FIG. 7 is a waveform diagram of the operational state of the sample-and-hold circuit under sample pulse control;
FIG. 8 is a logic flow diagram of two common primary side current sampling systems and the enumerated primary side current sampling systems;
FIG. 9 is a waveform diagram illustrating the operational state of the primary current sampling system as applied to an active clamp flyback converter;
fig. 10 is a schematic view of the working state of the present invention.
Detailed Description
The technical scheme of the invention is further described in detail below with reference to the accompanying drawings:
as shown in fig. 1, the listed primary side current sampling circuit includes: input filter capacitor C 1 Auxiliary transformer T 1 Filter capacitor C 2 Resistance R 1 Clamping diode D 1 RS trigger, delay unit B 1 Inverter I 1 Two-input OR gate 1 Two-input AND gate AND 1 Output inverter I 2 Sampling switch S 1 Sampling resistor R 2 Ground resistance R 3 Holding capacitor C 3 . Wherein, the filter capacitor C is input 1 Auxiliary transformer T 1 Filter capacitor C 2 Resistance R 1 Clamping diode D 1 Form the input stage to input the signal V in Converting the signal into a signal which can be identified by a digital circuit; RS trigger and delay unit B 1 Inverter I 1 Two-input OR gate 1 Two-input AND gate AND 1 Output inverter I 2 Form a sampling control circuit for controlling the sampling switch S in the sampling hold circuit 1 On/off of (a) and generate an output signal V out The method comprises the steps of carrying out a first treatment on the surface of the Sampling switch S 1 Sampling resistor R 2 Ground resistance R 3 Holding capacitor C 3 And a sampling and holding circuit is formed, the primary side electric signal of the main power transformer is sampled, and the sampled signal is held for a period of time. Auxiliary transformer T 1 Synchronous rectifying tube near secondary side of converterOne end of the circuit is a primary side, and one end close to the sampling control circuit is a secondary side. The input signal required by the input stage is connected with the input filter capacitor C 1 And auxiliary transformer T 1 Auxiliary transformer T between one ends of primary windings 1 The other end of the primary winding is provided with a filter capacitor C 1 The other end of the two parts is connected; one end of secondary winding of auxiliary transformer is connected with C 2 The other end is simultaneously connected with R 1 And clamping diode D 1 Positive electrode of D 1 Negative electrode of (A) and R 1 、C 2 And is connected with the reset end of the RS trigger. The Q end of the RS trigger is connected with the inverter I at the same time 1 Delay unit B 1 OR OR AND gate 1 Inverter I 1 The output of (1) is connected with AND gate AND 1 Delay unit B 1 Output simultaneous OR gate of (C) 1 AND gate AND 1 OR gate OR 1 The output of (a) is connected with an inverter I 2 Inverter I 2 The output of (a) is used as the output end of the sampling control circuit, AND AND gate 1 As output of the sampling pulse. The signal input end of the sample hold circuit is connected with the sampling resistor R 2 Sampling resistor R 2 S is connected with 1 One end of the switch and R 3 ，S 1 The other end of the switch is connected with a holding capacitor C 3 And simultaneously as a signal output end, R 3 And C 3 The other end is grounded, sampling switch S 1 The control end of the (C) is connected with the sampling pulse output end of the sampling control circuit.
The sampling control circuit adopts a pure digital circuit structure. As shown in FIG. 4, at the initial stage, V in 、V r 、V s 、V out At low level, V q 、V q1 Is high. When the synchronous rectifying tube of the secondary side is conducted, V in From low to high, resulting in V r Become high [ ] To assist the transformer turns ratio), RS flip-flop reset signal is active, V q The height is changed from high to low; due to delay unit B 1 V is the presence of q1 Will not go low immediately, resulting in AND gates 1 Output V of (2) s From low to high, the sampling switch S is actuated 1 And opening the sampling hold circuit, wherein the sampling hold circuit is in a sampling state. Through delay unit B 1 Time delay t of (2) d After that, V q1 From high to low, AND gate AND 1 Output V of (2) s At low level, the sampling switch is turned off; v (V) out From low to high. When the secondary synchronous rectifying tube is turned off, V in From high to low, resulting in V r Go low->The RS flip-flop reset signal is no longer valid, V q From low to high; due to delay unit B 1 V is the presence of q1 Will not become low immediately, V out Hold high level AND AND gate 1 Output V of (2) s The sample switch remains closed, remaining unchanged. And pass through delay unit B 1 Time delay t of (2) d After that, V q1 From low to high AND AND gate 1 Output V of (2) s Still at low level, the sampling switch remains off; v (V) out The height is changed from high to low. The flow of the sampling control strategy over one period of the converter is shown in fig. 5. V (V) in 、V out 、V s The waveform of (a) varies with time as shown in FIG. 6, giving a delay time t d ＝20ns。
The sampling hold circuit adopts a resistor-capacitor structure, and when the sampling switch is not opened, the sampling switch is Sample in The signal end passes through a resistor R 2 And R is 3 Grounded due to R 2 And R is 3 The series connection has larger resistance value, and the current in the main power transformer basically does not flow through the sampling branch. When V is s When the signal is effective and the sampling switch is opened, the current signal in the main power transformer flows through the resistor R 2 Converted into a voltage signal and output as Sample out . Because the sampling switch is opened for a short time, and the primary side current of the main power transformer is close to 0 when the synchronous rectifying tube at the secondary side of the converter is opened, the loss caused in the process is small and can be considered to be negligible. And due to the sampling resistor R 2 Has smaller resistance value and rootCan be set to be a few kΩ or even smaller according to the actual requirements of the circuit, so that higher sampling accuracy can be obtained. Through delay unit B 1 Time delay t of (2) d After that, the sampling switch is turned off and Sample is turned on in And Sample out Off due to holding capacitance C 3 Is applied to the obtained voltage signal Sample out Will remain at the value at the time of sampling and decay slowly; as long as C 3 The capacitance is large enough, sample out The signal can be held long enough to be provided to the subsequent control circuit. The waveform diagram of the sample-and-hold circuit is shown in fig. 4.
The input stage establishes an input signal with an auxiliary transformer. The input stage of synchronous rectifying tube grid signal of secondary side of converter adopts large capacitor to filter high-frequency harmonic wave, and utilizes auxiliary transformer T 1 Using electrical isolation between control circuit and main power topology, and using clamping diode D 1 To ensure that the control signal can trigger the RS flip-flop normally. The layout of the auxiliary transformer is divided into 4 layers as shown in fig. 2: the windings of the second layer and the third layer are primary sides, and the coils of the two layers pass through the through holes P 2 Series connection of P 1 And P 3 Respectively connect V to two ends of primary winding in Positive and negative ends of the signal; the windings of the first layer and the fourth layer are secondary sides and are mutually connected in parallel, and the through holes S 1 、S 2 For both ends of the first layer S 3 、S 4 Two ends of the fourth layer are respectively connected to the reset end of the RS trigger through the positive poles of the filter capacitor and the clamping diode; the whole auxiliary transformer is of a sandwich structure, so that leakage inductance and voltage spike are reduced, parasitic capacitance between layers of the auxiliary transformer is reduced, parasitic oscillation is correspondingly improved, common-mode interference current is reduced, and therefore EMI is improved. The whole auxiliary transformer takes air as a magnetic core, is arranged in the PCB without occupying area, and is mutually separated from the main power transformer, so that the influence on the main power transformer is reduced to the greatest extent, the board distribution is more flexible, and the auxiliary transformer can be placed at any position on the PCB if required. A schematic diagram of the cloth plate is shown in fig. 3. Besides, the air magnetic core also ensures that the auxiliary transformer can have a faster response speed and smaller hysteresis, and can generate a sampling pulse signal more accurately.
Compared with the traditional direct sampling or the sampling mode by depending on the auxiliary winding of the main power transformer, the control strategy provided by the invention has the advantages of simple logic, high reliability, easiness in implementation and more flexibility. Fig. 8 shows three sample control strategy flowcharts (digital circuit processing portions of all steps are integrated into one block diagram): the direct sampling control strategy is simpler, but the implementation is more complex, the analog circuit is mainly relied on, and the circuit is sensitive to factors such as device parameters, environmental parameters and the like and is easily influenced by noise; the auxiliary winding sampling strategy is used for realizing the signal conversion and processing of the main power transformer, and the auxiliary winding is added on the main power transformer, and the other parts related to the signal conversion and processing are realized by an integrated circuit, but the integrated circuit element with more complex logic is needed to be customized or adopted, and the position of the circuit on the PCB is limited due to the existence of the auxiliary winding; the sampling strategy has simple logic and easy realization, can be realized by only needing few logic gates and one trigger, is not easy to be influenced by device parameters and environmental factors, and the auxiliary transformer of the input stage is mutually independent from the main power transformer, can be placed at any position on the PCB if required, and is beneficial to reducing the area and saving the cost.
Compared with the direct sampling or the sampling mode by depending on the auxiliary winding of the main power transformer, the primary side current sampling circuit provided by the invention has the advantages of small area and low power consumption. The traditional direct sampling generally needs to lead out a branch from a main power transformer, convert a current signal into a voltage signal by using devices such as a resistor and the like, compare the voltage signal with a reference voltage through a comparator, generate higher loss due to direct contact with a main power loop, and have certain requirements on the precision of the comparator and the reference voltage; the auxiliary winding needs to be suitable for the size and shape of the main power transformer, the occupied area is large, the number of layers of the PCB is increased, and leakage inductance, parasitic capacitance and the like of the auxiliary winding can cause loss; the sampling hold circuit used in the invention is composed of two resistors, a capacitor and a switch, and has simple structure, small occupied area and only sampling pulseThe circuit is turned on in a short time when the circuit is in an effective state, and basically no current is generated when the circuit is turned off, so that the loss is small. On the basis, due to the sampling resistor R 2 The resistance of the circuit is smaller, and the circuit can be set to be a few kΩ or even smaller according to the actual requirement of the circuit, so that higher sampling precision is ensured.
The invention provides an application of an auxiliary transformer. The auxiliary transformer is used for establishing a reset signal of the RS trigger in the sampling control circuit, and realizes the electrical isolation between the sampling control circuit and the main power loop. As shown in fig. 2, the auxiliary transformer itself adopts a planar transformer sandwich winding method to reduce leakage inductance and voltage spike, and meanwhile, parasitic capacitance between layers of the auxiliary transformer is reduced, parasitic oscillation is correspondingly improved, and common-mode interference current is reduced, so that EMI is improved. In the example, the primary sides of the auxiliary transformers are connected in series, and the secondary sides of the auxiliary transformers are connected in parallel so as to adapt to the voltage of the synchronous rectifier tube grid signal and the signal required by the sampling control circuit; because the air magnetic core is adopted, the magnetic core is not required to be arranged by punching or grooving on the PCB, and the design and the board arrangement are convenient; because the power signal is not transmitted, even if air is used as a magnetic core, the loss brought by the air-core type sampling pulse generating device is very small compared with that of a main power transformer, and the air magnetic core can bring a response speed of a block and smaller delay, so that the sampling pulse can be quickly established. The number of layers of the PCB used by the auxiliary transformer is small, the whole auxiliary transformer has only 4 layers, and the auxiliary transformer is mutually independent with the main power transformer, is flexible in board distribution, can be placed in the PCB of the transformer, and can save area and reduce interference to other elements as shown in fig. 3.
Fig. 9 is a waveform diagram showing an operating state of the sampling system according to the present invention applied to an active clamp flyback converter. Synchronous rectifier grid signal V G Controlling the on and off of a synchronous rectifying tube at the secondary side of the converter; sampling signal input S in Primary side current I of primary power transformer p The voltage converted by the sampling resistor of the sampling hold circuit, the dotted line part represents that the sampling hold circuit is not started at the moment, and the actual voltage is close to 0; v (V) s For sampling pulse generated by sampling control circuit, pulse width is t d ；Sample out Is the wholeAnd a sampling result obtained by the primary side current sampling circuit. t is t 1 The synchronous rectifying tube of the secondary side is started at the moment, sampling pulse is established, a sampling switch in a sampling hold circuit is started, and the primary side current I is started p Sampling is performed. To t 1 +t d At the moment, the sampling pulse is ended, a sampling switch in the sampling hold circuit is turned off, and the sampling hold circuit holds the sampled signal before. t is t 2 The synchronous rectifying tube of the secondary side is turned off at the moment, no sampling pulse is generated, and the working state and t of the sampling hold circuit are 1 +t d The time instant is the same, holding the previously sampled signal.
Compared with the traditional sampling circuit and control method, the primary side current sampling circuit and the control strategy thereof provided by the invention have the following advantages:
table 1 three primary side current sampling circuits and control strategy comparison thereof
In the optimized embodiment, the whole primary side current sampling circuit can sample the primary side current of the main power transformer under the conditions of occupying little area and basically not generating extra power consumption, and ensures higher sampling precision, thereby reducing the area and the cost of the converter, improving the working efficiency and the reliability of the converter, reducing the power consumption, reducing the working interference and the noise of the converter and the like, and improving the working performance of the active clamping flyback converter.
Working principle:
as shown in fig. 1, the listed primary side current sampling circuit includes: input filter capacitor C 1 Auxiliary transformer T 1 Filter capacitor C 2 Resistance R 1 Clamping diode D 1 RS trigger, delay unit B 1 Inverter I 1 Two-input OR gate 1 Two-input AND gate AND 1 Output inverter I 2 Sampling switch S 1 Sampling resistor R 2 Ground resistance R 3 Holding capacitor C 3 . Wherein, the filter capacitor C is input 1 Auxiliary transformer T 1 Filter capacitor C 2 Resistance R 1 Clamping diode D 1 Form the input stage to input the signal V in Converting the signal into a signal which can be identified by a digital circuit; RS trigger and delay unit B 1 Inverter I 1 Two-input OR gate 1 Two-input AND gate AND 1 Output inverter I 2 Forming a sampling control circuit for controlling the on-off of the switch of the sampling hold circuit and generating an output signal V out The method comprises the steps of carrying out a first treatment on the surface of the Sampling switch S 1 Sampling resistor R 2 Ground resistance R 3 Holding capacitor C 3 And a sampling and holding circuit is formed to sample and hold the primary side electric signal of the main power transformer for a period of time. Auxiliary transformer T 1 One end close to the synchronous rectifying tube of the secondary side of the converter is taken as a primary side, and one end close to the sampling control circuit is taken as a secondary side. The input signal required by the input stage is connected with the input filter capacitor C 1 And auxiliary transformer T 1 Auxiliary transformer T between one ends of primary windings 1 The other end of the primary winding is provided with a filter capacitor C 1 The other end of the two parts is connected; one end of secondary winding of auxiliary transformer is connected with C 2 The other end is simultaneously connected with R 1 And clamping diode D 1 Positive electrode of D 1 Negative electrode of (A) and R 1 、C 2 And the sampling control circuits are connected and connected. The input stage is capable of establishing an input signal of the sampling control circuit using an auxiliary transformer. The sampling control circuit comprises an RS trigger and a delay unit B 1 Inverter I 1 Two-input OR gate 1 Two-input AND gate AND 1 Output inverter I 2 . The reset end of the RS trigger is used as the input end of the sampling control circuit. The Q end of the RS trigger is connected with the inverter I at the same time 1 Delay unit B 1 OR OR AND gate 1 Inverter I 1 The output of (1) is connected with AND gate AND 1 Delay unit B 1 Output simultaneous OR gate of (C) 1 AND gate AND 1 OR gate OR 1 The output of (a) is connected with an inverter I 2 Inverter I 2 The output of (a) is used as the output end of the sampling control circuit, AND AND gate 1 As output of the sampling pulse.
The primary side current sampling circuit of the invention takes the grid signal of the synchronous rectifying tube of the primary power topology secondary side of the converter as V in Signal V out The signal controls the conduction of the primary winding magnetizing inductor so as to ensure that energy can be transmitted to the secondary side; using primary side current signal of main power transformer as Sample in Signal, sample out For the resulting sampled signal.
The layout of the designed sampling control circuit auxiliary transformer is shown in fig. 2 (a), and (b), (c), (d) and (e) of fig. 2 respectively show windings of the auxiliary transformer on the first layer, the second layer, the third layer and the fourth layer of the PCB. The windings of the second layer and the third layer are primary sides, and the coils of the two layers pass through the through holes P 2 Series connection of P 1 And P 3 Respectively connect V to two ends of primary winding in Positive and negative ends of the signal; the windings of the first layer and the fourth layer are secondary sides and are mutually connected in parallel, and the through holes S 1 、S 2 For both ends of the first layer S 3 、S 4 Two ends of the fourth layer are respectively connected to the reset end of the RS trigger through the positive poles of the filter capacitor and the clamping diode; the whole auxiliary transformer is of a sandwich structure, and takes air as a magnetic core. The specific winding mode and port setting of the auxiliary transformer can be adjusted according to different specific layout. As shown in FIG. 3, the auxiliary transformer adopts an air magnetic core, and the number of the occupied PCB layers is only 4, so that the auxiliary transformer can be placed in the PCB without occupying surface space.
The invention provides a primary side current sampling control strategy of an active clamping flyback class, which has the following working principle: as shown in FIG. 4 (a), V is when the synchronous rectifier is turned on in From low level to high level, V after passing through auxiliary transformer r The low level is changed into the high level, the reset end of the RS trigger is effective to drive V q The signal is set low. V due to the action of the delay unit q1 After a delay (delay time t d Typically between 20-35 ns) is set low (fig. 4 (b)). Through time delay t d Thereafter, V out The signal goes high ensuring energy transfer to the secondary side. At t d Within the time period，V s The signal briefly goes high and once delayed by t d End V s The signal goes back low and thus a width t is created d Is a short pulse of (2). During the effective period of the short pulse, the sampling switch S is used for sampling 1 Control the conduction of the Sample hold circuit, for Sample in Sampling the signals; when the short pulse is invalid, the sample-hold circuit passes through the holding capacitor C 3 The obtained signal is sampled before the function of (1) is kept, and finally stable Sample is obtained out A signal. As shown in FIG. 4 (c), V when the synchronous rectifier is turned off in From high level to low level, V after passing through auxiliary transformer r The high level is changed into the low level, the set end of the RS trigger is valid, and V is changed from q The signal is set high. Through time delay t d Thereafter, V out The signal becomes low level, ensuring that the primary winding current can continue to flow t after the synchronous rectifier tube is closed d Further, the source-drain voltage of the primary power switching transistor is reduced to realize ZVS of the primary power switching transistor (fig. 4 (d)). Synchronous rectifier tube closing does not affect V s The sampling switch of the signal, sampling hold circuit is not opened. The waveform of the sampling control circuit generating the sampling pulse is shown in fig. 6. The sample-and-hold switching waveform under sample pulse control is shown in fig. 7, where the actual primary side waveform of the main power transformer is replaced by a standard sine wave.
The foregoing is only a partial embodiment of the present invention, and it should be noted that it will be apparent to those skilled in the art that modifications and adaptations can be made without departing from the principles of the present invention, and such modifications and adaptations are intended to be comprehended within the scope of the present invention.
Claims (8)
1. A low-loss primary side current sampling system of an active clamping flyback converter is characterized in that the sampling system comprises a primary side current sampling circuit,
the primary side current sampling circuit comprises an input stage, a sampling control circuit and a sampling hold circuit,
the output end of the input stage is connected with the reset end of the RS trigger in the sampling control circuit, and the sampling pulse output end of the sampling control circuit is connected with the control end of the sampling switch in the sampling hold circuit;
the input stage comprises an input filter capacitor C 1 Auxiliary transformer T 1 Filter capacitor C 2 Resistance R 1 Clamping diode D 1 Wherein, the auxiliary transformer T 1 One side close to the input signal is regarded as a primary side, one side close to the sampling control circuit is regarded as a secondary side, the secondary side is buried in the PCB of the converter, the input stage can establish the input signal of the sampling control circuit by utilizing the auxiliary transformer, and the input signal required by the input stage is connected with the input filter capacitor C 1 And auxiliary transformer T 1 Auxiliary transformer T between one ends of primary windings 1 The other end of the primary winding is provided with a filter capacitor C 1 The other end of the two parts is connected; one end of secondary winding of auxiliary transformer is connected with C 2 The other end is simultaneously connected with R 1 And clamping diode D 1 Positive electrode of D 1 Negative electrode of (A) and R 1 、C 2 The sampling control circuit is connected with the sampling control circuit, the sampling control circuit can control the working state of the sampling hold circuit according to the signal established by the input stage, and the sampling control circuit comprises an RS trigger and a delay unit B 1 Inverter I 1 Two-input OR gate 1 Two are respectively
Input AND gate AND 1 Output inverter I 2 The reset end of the RS trigger is used as the input end of the sampling control circuit, and the Q end of the RS trigger is connected with the inverter I at the same time 1 Delay unit B 1 OR OR AND gate 1 Inverter I 1 The output of (1) is connected with AND gate AND 1 Delay unit B 1 Output simultaneous OR gate of (C) 1 AND gate AND 1 OR gate OR 1 The output of (a) is connected with an inverter I 2 Inverter I 2 The output of (a) is used as the output end of the sampling control circuit, AND AND gate 1 As output of the sampling pulse.
2. The low-loss primary current sampling system of an active clamp flyback converter of claim 1 wherein the sample-and-hold circuit comprises a sampling switch S 1 Sampling resistor R 2 Ground resistance R 3 Holding capacitor C 3 The signal input end of the sample hold circuit is connected with the sampling resistor R 2 Sampling resistor R 2 S is connected with 1 One end of the switch and R 3 ，S 1 The other end of the switch is connected with a holding capacitor C 3 And simultaneously as a signal output end, R 3 And C 3 The other end is grounded, sampling switch S 1 The control end of the (C) is connected with the sampling pulse output end of the sampling control circuit.
3. The low-loss primary current sampling system of an active clamp flyback converter of claim 2 wherein the auxiliary transformer T 1 Air was used as the core.
4. The low-loss primary current sampling system of an active clamp flyback converter of claim 3 wherein the auxiliary transformer is positioned on the windings of the first, second, third and fourth layers of PCBs, the windings of the second and third layers being primary, the windings of the two layers being through-hole P 2 Series connection of P 1 And P 3 Respectively connect V to two ends of primary winding in Positive and negative ends of the signal; the windings of the first layer and the fourth layer are secondary sides and are mutually connected in parallel, and the through holes S 1 、S 2 For both ends of the first layer S 3 、S 4 Two ends of the fourth layer are respectively connected to the reset end of the RS trigger through the positive poles of the filter capacitor and the clamping diode; the whole auxiliary transformer is of a sandwich structure, and takes air as a magnetic core.
5. The low-loss primary current sampling system of an active clamp flyback converter of claim 1 wherein the sampling resistor R 2 The resistance value is set to be 0.5-2kΩ; ground resistance R 3 The resistance is set to 10-30kΩ.
6. A control method of a low-loss primary current sampling system employing an active clamp flyback converter according to any one of claims 1-5, characterized in that the method is as followsThe following steps: the input stage uses auxiliary transformer to realize electric isolation and voltage conversion, uses clamping diode to make signal be held, so as to create reset signal which can be adapted to post-stage digital circuit, uses converter secondary synchronous rectifier switching signal as input signal, and uses conversion of auxiliary transformer and holding of clamping diode to transfer signal to reset end of RS trigger in sampling control circuit, the sampling control circuit is digital circuit, and can utilize delay basic property of circuit itself, and can control working state of sampling and holding circuit according to signal created by input stage, and the RS uses output signal of input stage as reset signal, and the generated output signal and complementary signal of output signal are formed by inverter I 1 Realize the signal of reverse complementary, common input AND gate AND 1 OR OR AND gate 1 AND gate AND 1 Generating a sampling pulse signal for controlling the sample-hold switch due to the delay unit B 1 After 20-35ns, AND gate AND 1 The resulting sampling pulse signal becomes inactive, OR gate 1 Generates an output signal which is passed through an inverter I 2 The primary side of the primary power transformer is ensured to be conducted after the primary side of the primary power transformer is input to the converter, the sampling and holding circuit can sample the primary side current signal of the primary power transformer and can hold the sampled signal for a period of time, the sampling and holding circuit takes the primary side current signal of the primary power transformer as direct input and passes through the sampling resistor R 2 Converts the current signal into a voltage signal and passes through a sampling switch S 1 Transmitting to the output end of the sample hold circuit to obtain the required sampling signal, when the sampling switch S 1 When the circuit is started, sampling is carried out, and the output end of the sampling hold circuit outputs a signal obtained by sampling; when sampling switch S 1 When closed, due to the holding capacitance C 3 The signal at the output end of the sample-and-hold circuit is kept for a period of time, and the holding time and the holding capacitance C 3 Related to the parameters of (a).
7. The control method of claim 6, wherein the input stage generates an output according to the on-off condition of the synchronous rectifier of the secondary side of the converter, the output resetting the RS flip-flop of the sampling control circuit; the output signal of the RS trigger is delayed by the built-in delay unit, so that sampling pulses of tens of nanoseconds can be generated at the output end of the AND gate; the sampling pulse controls the on-off of a sampling switch in the sampling hold circuit so as to realize the sampling of primary side current of the main power transformer; and generating an output signal at the output end of the OR gate and feeding the output signal back to the primary side of the converter so as to ensure that the primary side of the main power transformer is in a conducting state in the whole sampling period.
8. The control method according to claim 7, wherein the control circuit sets different on-off states for the switches of the sample-and-hold circuit at different times according to the operating state of the synchronous rectifier of the secondary side of the converter, specifically as follows: in each converter period, when the secondary synchronous rectifier tube is conducted instantaneously, sampling pulse is effective, the effective duration is the delay of a delay unit in a sampling control circuit, a sampling switch is conducted in 20-35ns, and a sampling hold circuit samples primary side current; the rest of the time, the sampling pulse is inactive, and the sample-and-hold circuit holds the resulting signal sampled before.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010324535.XA CN111404359B (en) | 2020-04-23 | 2020-04-23 | Primary side current sampling system of active clamping flyback converter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010324535.XA CN111404359B (en) | 2020-04-23 | 2020-04-23 | Primary side current sampling system of active clamping flyback converter |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN111404359A CN111404359A (en) | 2020-07-10 |
| CN111404359B true CN111404359B (en) | 2023-08-08 |
Family
ID=71413739
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010324535.XA Active CN111404359B (en) | 2020-04-23 | 2020-04-23 | Primary side current sampling system of active clamping flyback converter |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN111404359B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113659839B (en) * | 2021-07-16 | 2023-03-31 | 杭州电子科技大学 | Primary side current analog circuit of flyback converter and using device thereof |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101841250A (en) * | 2010-04-27 | 2010-09-22 | 上海新进半导体制造有限公司 | Switching power supply control circuit and primary winding-controlled flyback switching power supply |
| CN101925237A (en) * | 2010-08-20 | 2010-12-22 | 杭州电子科技大学 | Primary constant-current control device of isolated type flyback converter |
| CN103248207A (en) * | 2013-05-21 | 2013-08-14 | 苏州智浦芯联电子科技有限公司 | Constant-current and constant-voltage fly-back converter based on primary side feedback |
| CN106793339A (en) * | 2017-02-06 | 2017-05-31 | 苏州智浦芯联电子科技股份有限公司 | Self adaptation line voltage compensation LED drive circuit based on primary side feedback |
-
2020
- 2020-04-23 CN CN202010324535.XA patent/CN111404359B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101841250A (en) * | 2010-04-27 | 2010-09-22 | 上海新进半导体制造有限公司 | Switching power supply control circuit and primary winding-controlled flyback switching power supply |
| CN101925237A (en) * | 2010-08-20 | 2010-12-22 | 杭州电子科技大学 | Primary constant-current control device of isolated type flyback converter |
| CN103248207A (en) * | 2013-05-21 | 2013-08-14 | 苏州智浦芯联电子科技有限公司 | Constant-current and constant-voltage fly-back converter based on primary side feedback |
| CN106793339A (en) * | 2017-02-06 | 2017-05-31 | 苏州智浦芯联电子科技股份有限公司 | Self adaptation line voltage compensation LED drive circuit based on primary side feedback |
Also Published As
| Publication number | Publication date |
|---|---|
| CN111404359A (en) | 2020-07-10 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Steigerwald et al. | A comparison of high-power DC-DC soft-switched converter topologies | |
| Zhang et al. | A novel ZVS DC/DC converter for high power applications | |
| CN101925237B (en) | Primary constant-current control device of isolated type flyback converter | |
| Chung et al. | A zero-current-switching PWM flyback converter with a simple auxiliary switch | |
| CN103066855B (en) | System and method used for no-voltage switch in power source transformation system | |
| Kotte et al. | High-speed (MHz) series resonant converter (SRC) using multilayered coreless printed circuit board (PCB) step-down power transformer | |
| Nayanasiri et al. | A switching control strategy for single-and dual-inductor current-fed push–pull converters | |
| CN111404359B (en) | Primary side current sampling system of active clamping flyback converter | |
| JPH0549251A (en) | Method for minimizing switching loss in power switching device | |
| Wu et al. | Active‐clamped ZVS current‐fed push–pull isolated dc/dc converter for renewable energy conversion applications | |
| Xue et al. | A novel bi-directional DC-DC converter for distributed energy storage device | |
| Wang et al. | The novel quasi-resonant flyback converter with autoregulated structure for parallel/serial input | |
| Hua et al. | Zero‐voltage‐transition bridgeless power factor correction rectifier with soft‐switched auxiliary circuit | |
| Cui et al. | High step down ratio (400 V to 1 V) phase shift full bridge DC/DC converter for data center power supplies with GaN FETs | |
| WO2024027360A1 (en) | Non-isolated full-bridge cascade converter circuit and control method therefor | |
| TWI650925B (en) | Switching power supply, control device and control method | |
| CN216873080U (en) | Photovoltaic system multiport DC-DC converter based on two-quadrant inverter topology unit | |
| Han et al. | A new full-bridge converter with phase-shifted coupled inductor rectifier | |
| CN1156079C (en) | Electronic switch transition process softening techn utilizing additional coupled winding | |
| CN110868078B (en) | Symmetrical half-bridge LC series resonance sine power conversion circuit | |
| CN108233756A (en) | A kind of double ground connection half-bridge inverters of single input and its control method | |
| Tiwari et al. | Design and development of a high step-up DC-DC Converter for non-conventional energy applications | |
| CN101604919A (en) | A kind of synchronous rectification Buck-Flyback converter | |
| Grimm et al. | An isolated gate driver for multi-active bridges with soft switching | |
| Mohammed et al. | Efficiency improvement of DC-DC boost converter by parallel switches connection |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |