Push-pull transformer driving system

Abstract

The invention discloses a push-pull transformer driving system which comprises a push-pull power supply controller and a converter. The push-pull power supply controller can control the converter to work safely and efficiently; the push-pull power supply controller is a push-pull power supply controller with an external power tube MOS (Metal Oxide Semiconductor); the push-pull power supply controller in the push-pull type transformer driving system adopts an external power tube mode, and a user can select a power tube with proper current and voltage according to own requirements, so that the maximization of the input voltage of the power supply and the output capability of large current can be realized to adapt to more application scenes; and different requirements of users are met.

Description

Technical Field

[0001] This invention belongs to the technical field of push-pull transformer drive, specifically relating to a push-pull transformer drive system in which the push-pull power controller adopts an external power transistor mode. Background Technology

[0002] Existing transformers may experience accidents or even damage when encountering excessively high or low voltages during operation; they may also fail to activate self-protection mechanisms when encountering abnormalities such as overheating or short circuits, which could lead to serious accidents; and the converter's volt-second balance may sometimes fail to recover properly, affecting normal operation.

[0003] To address this, we developed a push-pull transformer drive system that employs an external power transistor in the push-pull power controller. Summary of the Invention

[0004] The purpose of this invention is to provide a push-pull transformer drive system with an external power transistor in the push-pull power controller mode.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a push-pull transformer drive system, characterized in that it includes a push-pull power controller and a converter; the push-pull power controller adopts an external power transistor mode, and the user can select a power transistor with appropriate current and voltage according to their own needs, thereby maximizing the power input voltage and the output capability of large current.

[0006] Preferably, the push-pull power controller can operate normally under a low input voltage of 4.5V and will not be damaged under the impact of a high input voltage of 30V. Regardless of the high, medium, or low voltage of the external power transistor, the power supply can still perform high, medium, and low voltage monitoring.

[0007] Preferably, the push-pull power controller has a built-in soft-start module. As the power supply voltage increases, the soft-start module gradually increases the output current of the external drive transistor, so that the output current increases steadily and slowly, avoiding damage to the device due to the impact of a large current when the device is turned on.

[0008] Preferably, the push-pull power controller also has a built-in over-temperature protection module. When the temperature exceeds the specified range, it automatically enters a sleep state and can automatically resume operation if the temperature drops back to the set value.

[0009] Preferably, the push-pull transformer drive system is further provided with a clock oscillator to provide a clock signal for the push-pull output of the push-pull power controller.

[0010] Preferably, in order to be compatible with external synchronization applications, the push-pull transformer drive system is further equipped with a clock synchronization module, which can synchronize the working state of the push-pull power controller through an external clock signal.

[0011] Preferably, the transformer is a push-pull converter; the push-pull converter uses a transformer with a center tap to realize energy transfer from the primary side to the secondary side.

[0012] Compared with the prior art, the present invention provides a push-pull transformer drive system, which has the following advantages:

[0013] The push-pull power controller in the push-pull transformer drive system adopts an external power transistor mode. Users can select the appropriate current and voltage power transistor according to their own needs, thereby maximizing the power input voltage and the output capacity of large current to adapt to more application scenarios and meet different user needs. Attached Figure Description

[0014] Figure 1 This is a schematic diagram illustrating the working principle of the push-pull transformer drive system described in this invention.

[0015] Figure 2 This is a schematic diagram of the working principle of the push-pull converter in the push-pull transformer drive system described in this invention.

[0016] Figure 3 This is a driving waveform diagram of the push-pull converter in the push-pull transformer drive system described in this invention.

[0017] Figure 4 This is a magnetization curve diagram of the push-pull converter in the push-pull transformer drive system described in this invention.

[0018] Figure 5 This is a schematic diagram of the volt-second balance recovery principle of the push-pull converter in the push-pull transformer drive system described in this invention. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0020] This invention provides, for example Figure 1-5 The push-pull transformer drive system shown includes a push-pull power controller and a push-pull converter; the push-pull power controller can control the push-pull converter to work safely and efficiently.

[0021] The push-pull power controller is an external power transistor (MOSFET) push-pull power controller. It can operate normally under a low input voltage of 4.5V and will not be damaged by a high input voltage surge of 30V. The push-pull power controller has a built-in soft-start module to prevent damage to the device from the surge of large current during startup. It also has a built-in over-temperature protection module; when the temperature exceeds the specified range, it automatically enters a sleep state and automatically resumes operation when the temperature drops back to the set value. The push-pull transformer drive system also includes a clock oscillator to provide a clock signal for the push-pull output of the power controller. To accommodate external synchronization applications, the push-pull power controller also includes a clock synchronization module, which can synchronize the operating state of the power controller with an external clock signal.

[0022] As attached Figure 2 As shown, the push-pull converter uses a transformer with a center tap to achieve energy transfer from the primary to the secondary side; the drive waveforms of the drains VD1 and VD2 of the two power transistors Q1 and Q2 are shown in the attached figure. Figure 3 As shown; two power transistors Q1 and Q2 are turned on alternately, and the duration of these two on periods is equal, with a short time t between them. BBM Neither power transistor is turned on; that is, the drive levels of the two power transistors are quasi-complementary in timing, meaning that when one power transistor is turned on, the other is turned off. However, there is a short dead time at the switching point to ensure that the two power transistors do not turn on simultaneously to prevent current backflow. Figure 1 As shown in the red highlighted section, when Q1 is turned on, the input voltage V IN A current is driven through the lower half of the primary winding of the transformer, through Q1, to the reference ground. At the same time, the induced electromotive force of the secondary winding charges the output capacitor through diode D1. Similarly, when Q2 is turned on, the induced electromotive force charges the output capacitor through diode D2. This process is repeated continuously to obtain the required power supply on the secondary side of the power converter.

[0023] As attached Figure 4 As shown, the ideal magnetization curve of the push-pull converter has the magnetic flux density B (also known as magnetic induction intensity) on the vertical axis and the magnetic field strength H on the horizontal axis. When Q1 is turned on, the magnetic flux is pushed from point A to point A'; similarly, when Q2 is turned on, the magnetic flux is pulled back from point A' to point A. This repeated magnetic flux density B is related to the voltage V of the primary winding. LP and the MOSFET conduction time t ON The product of these terms is proportional and can be described by the following formula:

[0024] B≈V Lp ×t ON

[0025] This volt-second product VLp ×t ON The magnetization for each switching cycle is defined; if the volt-second product of the above "push" and "pull" phases is not exactly the same, a small DC component will be generated, causing a magnetic flux offset; if the balance cannot be restored, the magnetic flux offset will gradually increase in each subsequent switching cycle, causing the magnetic core to tend to saturate; this magnetic flux offset phenomenon is usually caused by unequal on-resistance or switching speed of the two power switching devices.

[0026] Fortunately, the on-resistance R of the power transistor MOSFET DS(on) It has a positive temperature coefficient, and thanks to this characteristic, the product has a self-correcting effect, suppressing volt-second imbalance; even with a slight deviation in the conduction time of the two power transistors (MOSFETs), the conduction time t... ON The longer power transistor generates relatively more heat, causing its temperature to rise and thus R... DS(on) If the voltage is increased, then during the conduction period with a constant load, the drain-source voltage V of this power transistor will increase. DS Relatively large; as attached Figure 5 As shown, the voltage V of the primary winding LP Satisfy V LP =V IN -V DS Therefore t ON Larger V LP It will gradually decrease in order to restore the volt-second balance.

[0027] During operation, the push-pull power controller first powers on and enters soft-start mode. As the power supply voltage increases, the output current of the external power transistor MOS gradually increases, so that the output current increases steadily and slowly, avoiding the large current impact on the circuit at the moment of power-on. After power-on, the over-temperature protection module starts to work to detect whether there is an abnormal state, such as over-temperature or short circuit. If so, the soft-start mode is restarted to reset the state. If not, the push-pull output mode is entered to supply power to the push-pull converter.

[0028] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A push-pull transformer drive system, characterized by: The push-pull power supply controller adopts an external power tube mode, and users can select a suitable current and voltage power tube according to their own needs, so as to realize the maximization of the input voltage of the power supply and the output capacity of a large current.

2. The push-pull transformer drive system of claim 1, wherein: The push-pull power supply controller can normally work under a low input voltage of 4.5V and will not be damaged under the impact of a high input voltage of 30V. Regardless of the high, medium and low voltage of the external power tube, the power supply can still achieve high, medium and low monitoring.

3. The push-pull transformer drive system of claim 1, wherein: The push-pull power supply controller is internally provided with a soft start module. With the increase of the power supply voltage, the soft start module gradually increases the output current of the external driving tube, so that the output current is slowly increased, and the damage of devices caused by the impact of large current during startup is avoided.

4. The push-pull transformer drive system of claim 1, wherein: The push-pull power supply controller is also internally provided with an over-temperature protection module. When the temperature exceeds the specified range, the module automatically enters a sleep state. If the temperature decreases to the set value again, the module can automatically recover.

5. The push-pull transformer drive system of claim 1, wherein: The push-pull transformer driving system is also provided with a clock oscillator, which provides a clock signal for the push-pull output of the push-pull power supply controller.

6. The push-pull transformer drive system of claim 1, wherein: In order to be compatible with external synchronous applications, the push-pull power supply controller is also provided with a clock synchronization module, which can synchronize the working state of the push-pull power supply controller through an external clock signal.

7. The push-pull transformer drive system of claim 1, wherein: The transformer is a push-pull transformer. The push-pull transformer uses a transformer with an intermediate tap to realize the energy transmission from the primary side to the secondary side.

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