TWI711265B - Main control system - Google Patents

Abstract

A main control system is applicable to an environment of a fully digital adjustable voltage half-wave secondary side fly back synchronous rectifier power supply. The secondary side controller actively sends the synchronous rectification MOS conduction control signal to control the secondary side MOS to adjust the secondary side output voltage, and transmit the reverse MOS conduction signal via the photo coupler isolator to the primary side self-start/gate driver to control the primary side MOS. With the main control system of the present invention, the secondary side is the main control of the entire feedback loop, and the secondary side MOS does not need to track the Vds to switch the conduction or not, and the conduction of the primary side MOS n is only the reverse of the secondary side MOS, so that the switching signal of the entire primary side MOS is extremely simplified.

Description

A master control system

The present invention relates to a main control system. More specifically, it relates to a main control system applied in the environment of a fully digital adjustable voltage half-wave secondary side main control feedback type synchronous rectification power supply.

Regarding the current mainstream half-wave feedback adjustable voltage voltage supply architecture, the current mainstream mobile phone charging power supply has a primary side power input voltage Vi in order to meet the world voltage, and its design specification is 700V, and The output voltage Vo of the secondary side is 20V according to the USB PD 100W specification.

The voltage feedback of the half-wave feedback adjustable voltage voltage supply is that the output voltage of the secondary side passes through a voltage-coupled voltage device feedback controller, and the current feedback is to use an auxiliary coil to convert the current signal into a voltage. Controller. The controller processes the voltage and current signals to adjust the energy entering the transformer, and the control method is switching MOS. The secondary side filter is used to achieve the filtering function, and this filter can be a passive diode or replaced with a synchronous rectifier composed of MOS to improve efficiency.

Traditionally, the entire loop controller is analog, and its stability and controllability are not as good as the full digital type, and the secondary side only passively provides energy from the primary side, and cannot actively demand energy. This design requires a voltage conversion transformer with good linearity to know the voltage output status of the secondary side, and the current sensing requires a special feedback voltage transformer to have the current sensing function. However, these two components are both analog linear components. It needs more expensive cost, and there will be problems with parts aging and linearity calibration.

Taiwan Patent Publication/Announcement No. 201122753 "Voltage Adjustment System" discloses a voltage adjustment system including a processor, a delay predictor, a controller, and a voltage supply. The processor has a variable delay functional unit, which is divided into multiple power regions. The functional unit generates a corresponding delay signal according to the current circuit speed. The delay predictor receives the delayed signal and predicts the performance of the processor according to the delayed signal to generate a predicted signal. The controller receives the prediction signal, compares the value of the prediction signal with at least one reference value, and generates a plurality of control signals according to the comparison result. The voltage supply is coupled to a first voltage source that provides a high voltage and a second voltage source that provides a low voltage. The voltage supply is switched according to the control signal generated by the controller to provide high or low voltage to multiple power supply areas of the functional unit.

Taiwan Patent Publication/Publication No. I579875 "A Variable Power Capacitor and Its Control Method and Application" provides a power capacitor for use in RF power delivery systems. The power capacitor includes at least two RF electrodes separated by a capacitor dielectric including a solid paradielectric material, the relative permittivity of the solid paradielectric material can be changed at the DC bias electrode Controlled by the DC bias applied to the dielectric. The configuration of the composite capacitor, the RF power system and the method of controlling the power capacitor are also described.

Taiwan Patent Publication/Publication No. I387206 "Voltage and Current Supply for Power Supply Compensation" discloses a device and method for providing a voltage or current for power supply compensation. A current and voltage source for supply compensation utilizes a differential amplifier connected to a bandgap reference voltage and a calibrated power supply voltage. When the power supply changes, the differential amplifier adjusts a stable compensated output. The output can be a compensation voltage or current. In addition, you can refer to multiple currents and voltages from the differential amplifier. The output of the stable compensation can be supplied as a reference bias voltage for external circuits. In addition, the compensation output can be supplied to a voltage controlled oscillator.

Taiwan Patent Publication/Publication No. 201825909 "Current Sense Amplifier Architecture and Level Shifter" discloses a high-end current sense amplifier architecture that uses only chopping, does not require automatic zeroing, and is easier to use (and Faster) switching capacitor filter instead of an auto-zero integration filter to simplify and improve the prior art current sense amplifier circuit. In addition, VIP (positive DC sense node) is combined with VDDHV (power supply) node, so that the integrated circuit package only needs a single node (package pin) to accommodate the VIP and VDDHV connections of the current sense amplifier circuit. This leads to the use of a smaller integrated circuit package. A small resistor is coupled between VIP and VDDHV to significantly reduce the bias voltage. Provides a high voltage level shifter with low delay time, which is necessary for precise chopping operation.

In other words, as far as the current conventional adjustable voltage voltage supply is concerned, how can the primary side power input voltage Vi of the mobile phone charging power supply not use a high voltage, for example, 700V; and, the feedback type adjustable voltage The voltage feedback of the voltage supply is not that the output voltage of the secondary side is fed back to the controller through a voltage-coupled voltage device, and the current feedback does not need to use the auxiliary coil on the primary side to convert the current signal into a voltage and send it to the control Furthermore, there is no need to use an analogous entire loop controller whose stability and controllability are not as good as the full digital type; in addition, how to solve the problem that the secondary side is only passively given energy from the primary side, and cannot actively demand energy , And there is no need for a voltage conversion transformer with good linearity to know the voltage output status of the secondary side. The current sensing requires a special feedback voltage transformer to have the current sensing function. However, these two components are both analog linear components. It needs more expensive cost, and there will be parts aging and linearity adjustment; therefore, how to overcome the various issues mentioned above is a problem to be solved.

The main purpose of the present invention is to provide a main control system, which is applied in the environment of a full digital adjustable voltage half-wave secondary side main control feedback type synchronous rectification power supply environment, and the secondary side controller will actively send out synchronization The conduction control signal of the MOS is rectified to control the MOS on the secondary side to adjust the output voltage of the secondary side, and the reverse MOS conduction signal is transmitted to the primary side through the opto-isolator to control the MOS on the primary side.

Another object of the present invention is to provide a main control system, which is applied in the environment of a fully digital adjustable voltage half-wave secondary side master control feedback type synchronous rectification power supply. The secondary side can actively request the primary side To give energy, the entire loop control is digital; in addition, there is no need for an active diode switching circuit on the secondary side, no special expensive main transformer that can detect current, no isolator that can transmit analog signals, but only transmission The digital signal isolator does not need a feedback isolation transformer for output voltage feedback. Instead, it uses the secondary side to synchronously actively control the voltage stabilization control. It can use the full digital control loop to prevent component aging and support fast charging protocols (for example, Mobile phone fast charging), digital interface and Internet of Things.

Another object of the present invention is to provide a main control system, which is applied in the environment of a full digital adjustable voltage half-wave secondary side main control feedback type synchronous rectification power supply environment, using the main control system of the present invention, two The secondary side is the main control of the entire feedback loop, and the MOS on the secondary side does not need to track Vds to switch on or off, and the MOS on the primary side is only the reverse of the MOS on the secondary side. The MOS switching signal on the side is extremely simplified.

Another object of the present invention is to provide a main control system, which is applied in the environment of a full digital adjustable voltage half-wave secondary side main control feedback type synchronous rectification power supply environment, using analog to digital conversion circuit ADC to convert The voltage, current, and temperature signals are converted to digital, so that not only can the aging problem of parts be reduced, a better controller can be used to achieve better power load calibration capability; and the digital design can also be used with fast charging The circuit of the protocol communicates with the downstream power draw device, and furthermore, the interface of the Internet of Things can be used to achieve the advantages of remote monitoring.

Another object of the present invention is to provide a main control system, which is applied in the environment of a full digital adjustable voltage half-wave secondary side main control feedback type synchronous rectification power supply. The power input voltage Vi does not use a high voltage, for example, 700V; and, the voltage feedback of the voltage supply of the feedback type adjustable voltage is not the output voltage of the secondary side through a voltage coupled voltage device and feedback to the controller, and The current feedback does not need to use the auxiliary coil on the primary side to convert the current signal into a voltage and transmit it to the controller; moreover, there is no need to use the entire loop controller whose stability and controllability are not as good as the full-digital analog type; , There is no need for a voltage conversion transformer with good linearity to know the voltage output status of the secondary side and current sensing requires a special feedback voltage transformer to have the current sensing function. In other words, there is no need to use a voltage conversion transformer with good linearity and special feedback Voltage device.

According to the above-mentioned purpose, the present invention provides a main control system applied to a full digital adjustable voltage half-wave secondary side main control feedback type synchronous rectification power supply. The main control system at least includes a controller and an opto-isolator , And self-start/gate driver.

The controller on the secondary side will actively send out the conduction control signal of the synchronous rectification MOS to control the MOS on the secondary side to adjust the output voltage of the secondary side, and transmit the reverse MOS conduction signal through the optocoupler isolator. To the Self Start/Gate Driver on the primary side to control the MOS on the primary side, here, the secondary side is the master of the entire feedback loop, and the MOS on the secondary side does not need to track Vds To switch on or off, and whether the MOS on the primary side is on or off is only the reverse of the MOS on the secondary side, so the entire MOS switching signal on the primary side is extremely simplified.

The architecture of the main control system applied to the full digital adjustable voltage half-wave secondary side master control feedback synchronous rectification power supply is the secondary side master control. Therefore, in the full digital adjustable voltage half-wave secondary side master control In the feedback-type synchronous rectification power supply, the transformer core does not store any magnetic flux energy in the electrical phase on the primary side and the output voltage at the output terminal is not yet established. Therefore, the controller of the main control system does not have enough voltage to operate, so just The machine will enter the auto-start mode when it is powered on. At this time, the MOS on the secondary side remains off (Vgs pull low of the MOS of the controller), and its body diode (BODY DIODE) is used as a passive diode; The self-starting circuit will send periodic pulses to turn on the MOS on the primary side, charge and discharge the transformer on the primary side, and use the MOS on the secondary side as passive rectifiers. At this stage, the entire circuit is in a half-wave feedback power supply. Architecture; In addition, when the output voltage of the secondary side is sufficient for the controller to operate normally, the controller will switch the entire circuit to the secondary side voltage regulation mode.

In addition, depending on actual needs, the main control system of the present invention can be matched with the digital interface (Digital I/F) of the output voltage terminal of the full digital adjustable voltage half-wave secondary side main control feedback type synchronous rectification power supply, using I2C to converge The BUS/power management bus PMBUS is connected to an external host (Host), and uses PD to DC (PD/DC) USB for Quick Charging Protocol (for example, fast charging of mobile phones).

In order to enable those skilled in the art to understand the purpose, features, and effects of the present invention, the following specific embodiments and accompanying drawings are used to explain the present invention in detail as follows:

Figure 1 is a schematic diagram showing the structure and operation of the fast charging system of the present invention. As shown in Figure 1, it is applied to the main control system 1 of a fully digital adjustable voltage half-wave secondary side main control feedback type synchronous rectification power supply. The main control system 1 includes at least a controller 2, an optocoupler isolation The self-starting/gate driver 4, wherein the optocoupler isolator 3 is electrically connected to the controller 2, and the self-starting/gate driver 4 is electrically connected to the optocoupler isolator 3.

Controller 2, the controller 2 on the secondary side will actively send out the conduction control signal of the synchronous rectification MOS to control the MOS on the secondary side to adjust the output voltage of the secondary side, and isolate the reverse MOS conduction signal through the optocoupler The device 3 is sent to the self-start/gate driver 4 on the primary side to control the MOS on the primary side. Here, the secondary side is the master of the entire feedback loop, and the MOS on the secondary side does not need to track Vds to switch On or off, and whether the MOS on the primary side is on or off is only the reverse of the MOS on the secondary side, so the MOS switching signal on the entire primary side is extremely simplified.

The architecture of the main control system 1 applied to the full digital adjustable voltage half-wave secondary side master control feedback synchronous rectification power supply is the secondary side master control. Therefore, in the fully digital adjustable voltage half-wave secondary side master In the control feedback synchronous rectification power supply, the transformer core does not store any magnetic flux energy on the primary side and the output voltage at the output terminal is not yet established, so the controller 2 of the main control system 1 does not have enough voltage to operate , So the machine will enter the auto-start mode when it is powered on. At this time, the MOS on the secondary side remains off (Vgs pull low of the MOS of the controller), and its body diode (BODY DIODE) is used as a passive diode; The self-starting circuit on the primary side will send periodic pulses to turn on the MOS on the primary side, charge and discharge the transformer on the primary side, and use the MOS on the secondary side as passive rectifiers. At this stage, the entire circuit is in half wave Feedback power supply architecture; In addition, when the output voltage of the secondary side is sufficient for the controller 2 to operate normally, the controller 2 will switch the entire circuit to the secondary side voltage regulation mode.

In addition, depending on actual needs, the main control system 1 of the present invention can be matched with the digital interface (Digital I/F) of the output voltage end of the full digital adjustable voltage half-wave secondary side main control feedback type synchronous rectification power supply with I2C The bus BUS/power management bus PMBUS is connected to an external host (Host), and uses PD to DC (PD/DC) USB to perform the Quick Charging Protocol (for example, fast charging of mobile phones).

FIG. 2 is a schematic diagram showing the architecture and an operation situation of an embodiment of the main control system of the present invention. As shown in Figure 2, it is applied to the main control system 1 of a fully digital adjustable voltage half-wave secondary side main control feedback type synchronous rectification power supply. The main control system 1 includes at least a controller 2, an optocoupler isolation The self-starting/gate driver 4, wherein the optocoupler isolator 3 is electrically connected to the controller 2, and the self-starting/gate driver 4 is electrically connected to the optocoupler isolator 3.

Controller 2, the controller 2 on the secondary side will actively send out the conduction control signal of the synchronous rectification MOS to control the MOS on the secondary side to adjust the output voltage of the secondary side, and isolate the reverse MOS conduction signal through the optocoupler The device 3 is sent to the self-start/gate driver 4 on the primary side to control the MOS on the primary side. Here, the secondary side is the master of the entire feedback loop, and the MOS on the secondary side does not need to track Vds to switch On or off, and whether the MOS on the primary side is on or off is only the reverse of the MOS on the secondary side, so the MOS switching signal on the entire primary side is extremely simplified.

In the self-start mode, the architecture of the main control system 1 applied to the full digital adjustable voltage half-wave secondary side master control feedback type synchronous rectification power supply is the secondary side master control. Therefore, in the full digital adjustable voltage The half-wave secondary side master control feedback type synchronous rectification power supply. On the primary side, the transformer T1 core does not store any magnetic flux energy and the output voltage Vo at the output terminal has not yet established voltage, so the main control system 1 Controller 2 does not have enough voltage to operate, so it will enter the auto-start mode when it is powered on. At this time, the MOS M2 on the secondary side remains off (the controller’s M2 Vgs pull low), and uses its body diode (BODY DIODE) as a passive diode; the self-starting circuit on the primary side will send out periodic pulses to turn on the MOS M1 on the primary side, and charge and discharge the transformer T1. The MOS M2 on the secondary side is a passive diode as a passive rectifier. At this stage, the entire circuit is in a half-wave feedback power supply architecture; in addition, when the voltage of the output voltage Vo on the secondary side is sufficient for the controller to operate normally, the controller will switch the entire circuit to the secondary side voltage regulation mode.

Here, the relationship between the voltage and the transformer from the primary side is as follows: Vin: The output of the primary side rectifier is also the input of the flyback transformer. Vp: Flyback voltage on the primary side. The input terminal of the voltage converter. Vs: is the output voltage induced on the secondary side. Np: The number of coils on the primary side. Ns: The number of first laps on the secondary side. D1: T1_ON/T1_OFF, the ratio of M1 MOS switching time on the primary side. D2: T2_ON/T2_OFF, the ratio of M2 MOS switching time on the secondary side. Vp/Vs=Ns/Np =>Vp=Vs*Np/Ns-------------------(1) Vp=D1*Vin-----------------------(2) It can be inferred from (1)(2) that Vs=D1*Vin*Ns/Np -----------(3) The above is the output voltage relationship between primary side master control and secondary side passive rectification and filtering. At this point, from the perspective of the secondary side, the switch of M2 and the switch of M1 are just the opposite. D1= T1_ON/T1_OFF= T2_OFF/T2_ON=1/D2-----(4) It can be inferred from (3)(4) that Vs=(1/D2)*Vin*Ns/Np Therefore, Vs/D1=Vs*D2=Vin*Ns/Np From this relationship, when the secondary side is the master, the switch relationship on the primary side is also an inverted relationship.

In addition, depending on actual needs, the main control system 1 of the present invention can be used with the digital interface 5 of the output voltage Vo terminal of the full digital adjustable voltage half-wave secondary side main control feedback type synchronous rectification power supply, using the I2C bus BUS/ The power management bus PMBUS is connected to an external host (Host), and uses PD to DC (PD/DC) USB to perform the Quick Charging Protocol (for example, fast charging of mobile phones).

M3 is the output switch. When abnormal or the charging protocol communicates, the power supply is turned off.

FIG. 3 is a schematic diagram for showing another operation situation of the embodiment of the main control system of the present invention illustrated in FIG. 2. FIG. As shown in Figure 3, it is the secondary side operation mode.

In the secondary side operation mode, the Vds of the M2 reads the linear current obtained by digital conversion to the digital conversion circuit ADC (Isense) 6 through the differential circuit for temperature calibration. The secondary side controller 2 senses the voltage and current conditions by Isense (analog to digital conversion circuit ADC) 6, and feeds back to the controller 2 which is a digital controller (PID, etc.). Because it is the entire digital control loop, the controller 2 can not only change the pulse width modulation PWM, pulse frequency modulation PFM or constant on-time COT mode, but also use nonlinear techniques to help the loop reaction time and stability .

The controller 2 which is a digital controller will send the Vg control voltage of M2, and the controller 2 will send the Vg control voltage of the primary side M1 through the opto-isolator 3 and the self-start/gate driver 4.

The feedback type iron core transformer T1 can achieve the effect of energy conservation, and the conduction time of M2 and M1 are mutually exclusive. The dead time Td (DeadTime) in the middle can be controlled by the controller 2 to open the circuit without being too big. The inductance power outage surge problem. For power supply efficiency, the dead time Td (DeadTime) of M1 and M2 switches is as small as possible. The optimized design can send a pulse width modulation PWM from the secondary side to the primary side during the engineering development stage, and then use the transformer T1 The delay time of the secondary side can be used to set the dead time Td (DeadTime) optimization.

M3 is the output switch. When abnormal or the charging protocol communicates, the power supply is turned off.

FIG. 4 is a schematic diagram for showing still another operation situation of the embodiment of the main control system of the present invention illustrated in FIG. 2. As shown in Figure 4, it is the secondary side operation mode.

When M2 is turned off, M1 will turn on to charge the transformer T1. The Vg of M1 just sends a simple ON/OFF signal to the gate driver of the self-start/gate driver 4 through the optocoupler isolator 3, without signal processing. The concept is that the controller 2 extends the pulse width modulation PWM control M1 through the opto-isolator 3.

The M1 on the primary side stores energy in the transformer T1 when M2 is closed for the next M2 to be turned on and extracted.

M3 is the output switch. When abnormal or the charging protocol communicates, the power supply is turned off.

Based on the above embodiments, we can obtain a main control system of the present invention, which is applied to the environment of a fully digital adjustable voltage half-wave secondary side master control feedback type synchronous rectification power supply. The device will actively send out the conduction control signal of the synchronous rectification MOS to control the MOS on the secondary side to adjust the output voltage of the secondary side, and transmit the reverse MOS conduction signal to the self-start/gate of the primary side through the opto-isolator The pole driver controls the MOS on the primary side. With the main control system of the present invention, the secondary side is the main control of the entire feedback loop, and the MOS on the secondary side does not need to track Vds to switch on or off, and the MOS on the primary side is only on the secondary side. The reverse of MOS, so the MOS switching signal of the entire primary side is extremely simplified. The main control system of the present invention includes the following advantages: 1. The controller on the secondary side will actively send a synchronous rectification MOS conduction control signal to adjust the output voltage of the secondary side, and transmit the reverse MOS conduction signal to the primary side through the optocoupler isolator to control the primary side MOS. 2. The secondary side can actively request energy from the primary side, and the entire loop is controlled by digital; in addition, there is no need for an active diode switching circuit on the secondary side, no need for a special expensive main transformer that can detect current, and no need for Isolators that can transmit analog signals but only need to transmit digital signals, do not need a feedback isolation transformer for output voltage feedback, but use secondary side synchronous active control voltage regulation control, and can use full digital control loops to prevent parts It is aging and supports fast charging protocol, digital interface and Internet of Things. 3. With the main control system of the present invention, the secondary side is the main control of the entire feedback loop, and the MOS on the secondary side does not need to track Vds to switch on or off, and the MOS on the primary side is only on or off. The reverse of the secondary side makes the MOS switching signal of the entire primary side extremely simplified. 4. Use analog-to-digital conversion circuit ADC to convert voltage, current and temperature signals into digital. This will not only reduce the aging problem of parts, but also use better controllers to achieve better power load calibration capabilities; However, the digital design can also cooperate with the circuit of the fast charging protocol to communicate with the downstream power drain device, and furthermore, the interface of the Internet of Things can be used to achieve the advantages of remote monitoring.

The above descriptions are only preferred embodiments of the present invention and are not intended to limit the scope of the present invention; all other equivalent changes or modifications made without departing from the spirit of the present invention should be included in the following patents Within range.

1: Main control system 2: Controller 3: Optocoupler isolator 4: Self-start/gate driver 5: Digital interface 6: Digital conversion circuit ADC M1: MOS M2: MOS M3: Output switch T1: Transformer

Figure 1 is a schematic diagram showing the structure and operation of the fast charging system of the present invention; Figure 2 is a schematic diagram showing the architecture of an embodiment of the main control system of the present invention, and an operating situation; Figure 3 is a schematic diagram showing another operation situation of the embodiment of the main control system of the present invention illustrated in Figure 2; and FIG. 4 is a schematic diagram for showing still another operation situation of the embodiment of the main control system of the present invention illustrated in FIG. 2.

1: Main control system

2: Controller

3: Optocoupler isolator

4: Self-start/gate driver

Claims (10)

A main control system, which is used in the environment of a full digital adjustable voltage half-wave secondary side main control feedback type synchronous rectification power supply, including: a controller; an analog-to-digital conversion circuit, the analog-to-digital conversion circuit and the The controller is electrically connected; an optocoupler isolator, which is electrically connected to the controller; and a self-start/gate driver, which is electrically connected to the optocoupler isolator; wherein , The analog-to-digital conversion circuit on the secondary side senses the voltage and current conditions and feeds them back to the controller; and the controller on the secondary side will actively send out a synchronous rectification MOS conduction control signal to control the secondary The MOS on the secondary side adjusts the output voltage of the secondary side. The controller transmits a reverse MOS conduction signal to the self-start/gate driver on the primary side via the optocoupler isolator to control the MOS on the primary side. The main control system described in item 1 of the scope of patent application, wherein the controller of the secondary side is the main control of the feedback loop. For the master control system described in item 1 of the scope of patent application, whether the MOS on the primary side is turned on is only the reverse of the MOS on the secondary side. For the master control system described in item 3 of the scope of patent application, wherein, in the self-start mode, the MOS on the secondary side is turned off, and the body diode of the MOS is used as a passive diode; in addition, when the The MOS on the secondary side is off, and the MOS on the primary side is on. The main control system described in item 3 of the scope of patent application, wherein, in the voltage stabilization mode of the secondary side, the MOS on the primary side is on, and the MOS on the secondary side is off. A main control system, which is used in the environment of a full digital adjustable voltage half-wave secondary side main control feedback type synchronous rectification power supply, including: a controller; an analog-to-digital conversion circuit, the analog-to-digital conversion circuit and the The controller is electrically connected; an optocoupler isolator, which is electrically connected to the controller; and a self-start/gate driver, which is electrically connected to the optocoupler isolator; wherein , The analog-to-digital conversion circuit on the secondary side senses the voltage and current conditions and feeds them back to the controller; the controller on the secondary side will actively send out a synchronous rectification MOS conduction control signal to control the secondary side MOS adjusts the output voltage of the secondary side, the controller transmits a reverse MOS conduction signal to the self-start/gate driver on the primary side via the optocoupler isolator to control the MOS on the primary side; and The main control system cooperates with the digital interface of the output voltage terminal of the full digital adjustable voltage half-wave secondary side main control feedback type synchronous rectification power supply, and is connected to the external host via I2C bus BUS/power management bus PMBUS , Use PD to DC (PD/DC) USB for fast charging protocol. The main control system described in item 6 of the scope of patent application, wherein the controller of the secondary side is the main control of the feedback loop. As for the master control system described in item 6 of the scope of patent application, the conduction of the MOS on the primary side is only the reverse of the MOS on the secondary side. For the master control system described in item 8 of the scope of patent application, wherein, in the self-starting mode, the MOS on the secondary side is turned off, and the body diode of the MOS is used as a passive diode; The MOS on the secondary side is off, and the MOS on the primary side is on. The main control system described in item 8 of the scope of patent application, wherein, in the voltage stabilization mode of the secondary side, the MOS on the primary side is turned on, and the MOS on the secondary side is turned off.

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