WO2022007617A1

WO2022007617A1 - Power adapter

Info

Publication number: WO2022007617A1
Application number: PCT/CN2021/101024
Authority: WO
Inventors: 江森龙; 田晨; 张加亮
Original assignee: Oppo广东移动通信有限公司
Priority date: 2020-07-10
Filing date: 2021-06-18
Publication date: 2022-01-13
Also published as: CN113922672A

Abstract

A power adapter. The power adapter comprises an electric energy conversion unit (20) and a clamping unit (21). The electric energy conversion unit (20) is used for performing alternating-current-to-direct-current conversion on alternating-current electric energy, or for performing direct-current conversion on pulsed direct-current electric energy formed after the alternating-current electric energy is rectified; and the clamping unit (21) is connected to an input end and an output end of the electric energy conversion unit (20), so as to control, when the difference value between an input end voltage and an output end voltage of the electric energy conversion unit (20) is greater than or equal to a first difference value, the electric energy conversion unit to reduce an output voltage. The present invention improves the adaptability of the power adapter used in external power supply environments having different quality, and improves the working stability of the power adapter. (FIG. 1)

Description

Power Adapter

This application requires a Chinese patent application filed on July 10, 2020 with the application number 202010664240.7 and titled "Adapter", and a Chinese patent application filed on July 16, 2020 with the application number 202010688715.6 and the title of "Power Adapter" The priority of the Chinese patent application of the Chinese patent application, the entire content of which is incorporated herein by reference.

technical field

The present disclosure relates to the field of electronic equipment, and in particular, to a power adapter and a mobile power source.

Background technique

With the widespread application of electronic devices (such as smart phones, tablet computers, and other smart terminal devices), their functions are increasing, but their power consumption is also increasing accordingly, requiring frequent charging. Due to its portability, the adapter often needs to be connected to and adapted to power sources with different power qualities.

SUMMARY OF THE INVENTION

The present disclosure provides a power adapter and a mobile power source.

According to a first aspect of the present disclosure, there is provided a power adapter, comprising: a power conversion unit for performing AC-DC conversion on AC power, or for performing DC-DC conversion on pulsating DC power formed by rectifying the AC power; a clamp a unit connected to the input terminal and the output terminal of the power conversion unit, so as to control the power conversion unit to lower the voltage when the difference between the input terminal voltage and the output terminal voltage of the power conversion unit is greater than or equal to the first difference The output voltage.

According to a second aspect of the present disclosure, there is provided a mobile power supply, including a power adapter; the power adapter includes: a power conversion unit for performing AC-DC conversion on AC power, or for converting AC power after rectification. The pulsating DC power is DC converted; the clamping unit is connected to the input terminal and the output terminal of the power conversion unit, so that the difference between the input terminal voltage and the output terminal voltage of the power conversion unit is greater than or equal to the first difference value When the power conversion unit is controlled to reduce the output voltage.

Description of drawings

1 is a circuit block diagram of a power adapter of the present disclosure according to an embodiment;

2 is a circuit block diagram of a power adapter in the related art shown according to an embodiment;

3 is a circuit block diagram of a power adapter of the present disclosure according to another embodiment;

FIG. 4 is a circuit block diagram of a power adapter of the present disclosure according to another embodiment;

5 is a schematic diagram showing the relationship between the output current and time of the power adapter during the charging process under different filter capacitors;

FIG. 6 is a graph showing the input voltage and output voltage of the adapter after using the chopper unit according to an example;

7 is a circuit block diagram of a power adapter according to an example;

8 is a circuit block diagram of a power adapter according to another example;

FIG. 9 is a circuit block diagram of a power adapter according to another example;

FIG. 10 is a circuit block diagram of a power adapter according to another example;

11 is a circuit diagram of a chopper unit shown according to an example;

FIG. 12 is a partial circuit diagram of a power adapter according to an example.

detailed description

Example embodiments will now be described more fully with reference to the accompanying drawings. Example embodiments, however, can be embodied in various forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example embodiments to those skilled in the art. The drawings are merely schematic illustrations of the present disclosure and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and thus their repeated descriptions will be omitted.

Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided in order to give a thorough understanding of the embodiments of the present disclosure. However, those skilled in the art will appreciate that the technical solutions of the present disclosure may be practiced without one or more of the specific details, or other methods, components, devices, steps, etc. may be employed. In other instances, well-known structures, methods, devices, implementations, materials, or operations have not been shown or described in detail to avoid obscuring aspects of the present disclosure.

In the present disclosure, unless otherwise expressly specified and limited, the terms "installed", "connected", "connected", "fixed" and other terms should be understood in a broad sense, for example, it may be a fixed connection or a detachable connection It can be a mechanical connection, an electrical connection or can communicate with each other; it can be directly connected, or it can be indirectly connected through an intermediate medium, it can be the internal communication between two elements or the interaction relationship between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present disclosure can be understood according to specific situations.

In addition, the terms "first" and "second" are only used for descriptive purposes, and should not be construed as indicating or implying relative importance or implying the number of indicated technical features. Thus, a feature defined as "first" or "second" may expressly or implicitly include one or more of that feature. In the description of the present disclosure, "plurality" means at least two, such as two, three, etc., unless expressly and specifically defined otherwise.

When the power supply connected to the adapter is relatively stable, the voltage output by the adapter is correspondingly relatively stable. However, when the power supply connected to the adapter fluctuates greatly, it will cause some components in the adapter to work in extreme environments and fail to work, causing the entire adapter circuit to collapse, and even causing the adapter to have safety problems.

In view of the above problems, the present disclosure provides a power adapter. The preferred embodiments of the present disclosure will be further elaborated below with reference to the accompanying drawings of the present specification.

In order to understand the present application more clearly, the working principle and process of the power adapter will be introduced below with reference to FIG. 1 , so as to facilitate the subsequent understanding of the solution of the present application. However, it should be understood that the content introduced below is only for a better understanding of the present application, and should not be specifically limited to the present application.

Among them, the power adapter is, for example, a power adapter, a power bank (Power Bank) and other devices. The power adapter is connected with the device to be charged through a cable, and provides electrical energy for the device to be charged to charge the battery in the device to be charged.

The types of power adapters can be classified into, for example, a normal charging type and a quick charging type. Compared with the ordinary charging type power adapter, the fast charging type power adapter can provide greater output power for the device to be charged. The maximum output power of an ordinary charging type power adapter is 10W (5V/2A). The fast charging type can be further divided into a first fast charging type and a second fast charging type. The maximum output power of the power adapter of the first fast charging type is, for example, 20W (5V/4A); the maximum output power of the power adapter of the second fast charging type is, for example, 50W (10V/5A).

The device to be charged can be, for example, a terminal or an electronic device, and the terminal or electronic device can be a mobile phone, a game console, a tablet computer, an e-book reader, a smart wearable device, an MP4 (Moving Picture Experts Group Audio Layer IV, a moving picture expert compressed standard audio level) players, smart home devices, AR (Augmented Reality, augmented reality) devices, VR (Virtual Reality, virtual reality) devices and other mobile terminals; it can also be mobile power sources (such as power banks, travel chargers), electronic cigarettes, wireless A rechargeable electronic device with a charging function, such as a mouse, a wireless keyboard, a wireless earphone, a Bluetooth speaker, etc.; or, a personal computer (Personal Computer, PC), such as a laptop portable computer and a desktop computer, etc.

The power adapter has a charging interface for connecting the device to be charged, and the charging interface may be a USB interface, specifically a TYPE-C interface. The charging interface can be, for example, a USB interface that complies with the USB 2.0 specification, the USB 3.0 specification, or the USB 3.1 specification, including: a Micro USB interface or a USB TYPE-C interface. In some embodiments, the charging port may also be a lightning port, or any other type of parallel port or serial port that can be used for charging.

Correspondingly, the charging interface on the device to be charged may be a male connector of a USB interface or Lightning interface that is compatible with the charging interface and meets the USB 2.0 specification, the USB 3.0 specification, or the USB 3.1 specification.

For example, the power adapter can communicate with the device to be charged through the charging interface and the charging interface, and both parties do not need to set up additional communication interfaces or other wireless communication modules. If the charging interface and the charging interface are USB interfaces, the power adapter and the device to be charged can communicate based on data lines (eg, D+ and/or D- lines) in the USB interface. Another example is that the charging interface and the charging interface are USB interfaces (such as USB TYPE-C interfaces) that support the power transfer (PD) communication protocol, then the power adapter and the device to be charged can communicate based on the PD communication protocol. In addition, the power adapter and the device to be charged can also communicate through other communication methods other than the charging interface and the charging interface. For example, the power adapter and the device to be charged communicate wirelessly, such as near field communication (NFC).

Taking both the charging interface and the charging interface as USB interfaces as an example, when the device to be charged and the power adapter are connected by a cable, the device to be charged identifies whether the connection port provided by the power adapter is a dedicated charging port (DCP). , this port does not support data transmission and can provide a charging current of more than 1.5A, and the D+ and D- lines of the port are short-circuited. This type of port can support higher charging capacity chargers and car chargers. Specifically, the device to be charged identifies whether the connection port provided by the power adapter is DCP through the BC2.1 protocol. BC2.1 is the USB charging specification, which regulates the detection, control and reporting mechanism of device charging through the USB port. The BC2.1 protocol is well known to those of ordinary skill in the art, and in order to avoid obscuring the present disclosure, details are not repeated here.

Please refer to FIG. 1, which is a circuit block diagram of a power adapter of the present disclosure according to an embodiment; in an embodiment, the power adapter includes a power conversion unit 20 and a clamping unit 21. The power conversion unit 20 is used for AC-DC conversion for AC power, or for DC conversion for the rectified pulsating DC power; the clamping unit 21 is connected to the input end and the output end of the power conversion unit 20 to convert the power When the voltage difference between the input end and the output end of the unit 20 is greater than or equal to the first difference, the power conversion unit 20 is controlled to lower the output voltage.

In this embodiment, the type of power source connected to the power adapter is not limited, and it can be connected to a DC power source or an AC power source, such as commercial power. It should be understood that the power conversion unit 20 can be directly connected to an external power source, and perform AC-DC conversion or DC-DC conversion on the external power source. The power adapter may also have a rectifier circuit or other circuits for power conversion. The power conversion unit 20 can cooperate with other circuit units to process the power in the intermediate links.

The setting of the clamping unit 21 enables the load (the device to be charged) to draw a larger current when the voltage output by the power conversion unit 20 is high, and when the voltage output by the power conversion unit 20 is low, the load (the device to be charged) The ability to draw current is also reduced accordingly, so that the power adapter circuit will not collapse due to excessive current drawn by the load, which improves the adaptability of the power adapter to external power supply environments of different quality, and ensures the power adapter works. stability.

The present disclosure further improves the adapter circuit by utilizing the ability of the clamping unit to maintain the working stability of the adapter, so as to reduce the size of the adapter and reduce the impact on the working stability of the adapter while realizing the miniaturization of the adapter. .

As shown in FIG. 2 , FIG. 2 is a circuit block diagram of a power adapter in the related art according to an embodiment. The power adapter may include a primary rectifier circuit 12 , a primary filter circuit 13 , a transformer 14 , a secondary rectifier circuit 15 , a secondary filter circuit 16 , a switching device 17 , a control chip 18 , and a feedback circuit 19 . Among them, the primary filter circuit 13 and the secondary filter circuit 16 usually use electrolytic capacitors with large capacitance and high voltage resistance. The capacitance value of the filter capacitor 23 used by the secondary filter circuit 16 is generally above 600uF, and usually at least two are required. The size of the electrolytic capacitor is relatively large, which occupies a considerable space in the power adapter, so that the power adapter cannot be further miniaturized.

The power adapter provided by the embodiment of the present application can reduce the volume of the power adapter and realize the miniaturization of the volume of the power adapter.

Please refer to FIG. 3 , which is a circuit block diagram of a power adapter of the present disclosure according to another embodiment. In an embodiment of the present disclosure, the power adapter includes at least one filter capacitor 23 , a power conversion unit 20 , and a clamping unit 21 . The capacitance value of at least one filter capacitor 23 is smaller than the preset capacitance value, which is used to filter the rectified AC power to obtain pulsating DC power; the power conversion unit 20 is used to convert the AC power to AC and DC, or to The rectified pulsating DC power is converted to DC; the clamping unit 21 is connected to the input end and the output end of the power conversion unit 20, so that when the voltage difference between the input end and the output end of the power conversion unit 20 is greater than or equal to the first difference , control the power conversion unit 20 to lower the output voltage.

Specifically, the power conversion unit 20 includes a DC conversion circuit 201 and a control circuit 202 for controlling the chopping frequency of the DC conversion circuit 201; the DC conversion circuit 201 is used to chop the rectified AC power; the clamping unit 21 has a first input The control circuit 202 has a feedback terminal; the first input terminal of the clamping unit 21 is connected to the input terminal of the DC conversion circuit 201, and the second input terminal of the clamping unit 21 is connected to the DC conversion circuit 201. The output terminal of the clamping unit 21 is connected to the control circuit 202; when the difference between the voltage of the first input terminal and the voltage of the second input terminal is greater than or equal to the first difference, the output terminal of the clamping unit 21 outputs The control signal is sent to the feedback end of the control circuit 202 to trigger the control circuit 202 to lower the duty cycle of the output PWM wave or stop the output of the PWM wave.

The capacitance value of the filter capacitor 23 in this embodiment of the present application may be smaller than a preset threshold, and the preset threshold may be determined according to the output power level of the power adapter, for example, 100uF, 200uF, 300uF, 400uF, 500uF, etc. When the capacitance of the filter capacitor 23 is smaller than the preset threshold, its volume is relatively small, so the volume of the power adapter can be reduced as much as possible, thereby realizing the miniaturization of the power adapter. The specific setting example of the filter capacitor 23 will be described later in conjunction with the example of the DC conversion circuit.

The power conversion unit 20 may be an AC-DC conversion unit (AC-DC), or a direct current conversion unit (DC-DC). Specifically, one or more of a rectifier bridge circuit, a buck circuit, a boost circuit, a buck-boost circuit, and a charge pump circuit may be cascaded. Specifically, it can be set according to the input power supply and the voltage to be output.

In an example, the input power supply is an AC power supply. At this time, the power adapter further includes a rectifier circuit 22. The rectifier circuit 22 is used to rectify the AC power, and the rectified pulsating DC can be boosted or bucked by the DC conversion unit. .

In another example, the input power supply is a DC power supply, and in this case, the power adapter can be directly provided with a DC conversion unit without setting the rectifier circuit 22 .

The above-mentioned filter capacitor 23 is provided on the input side of the power conversion unit 20 for filtering the input DC power, so as to stabilize the voltage input to the power conversion unit 20 . The above-mentioned filter capacitor 23 may also be provided on the output side of the power conversion unit 20 to filter the DC power after DC conversion, so as to make the voltage more stable. Of course, the above-mentioned filter capacitor 23 may also be provided on the input side and the output side of the power conversion unit 20 at the same time.

See Figure 4. FIG. 4 is a circuit block diagram of a power adapter of the present disclosure according to another embodiment. Wherein, the capacitance value of at least one first filter capacitor 231 is smaller than the preset capacitance value, which is used to filter the rectified AC power to output pulsating DC power; the at least one first filter capacitor 231 is connected to the input end of the power conversion unit 20 . connect. The power adapter also includes at least one second filter capacitor 232, and the capacitance value of the at least one second filter capacitor 232 is smaller than the preset capacitance value; the at least one second filter capacitor 232 is connected to the output end of the power conversion unit 20 for converting the DC power The electrical energy output by the conversion unit 20 is filtered.

The number of filter capacitors 23 is determined by the required capacity of the capacitor. When there are multiple filter capacitors 23, they can be connected in series or in parallel. Specifically, assuming that the required capacitance of the capacitor is 10uF, if the capacitance of one filter capacitor 23 is 5uF, two filter capacitors 23 can be connected in parallel to meet the required capacitance of the capacitor. If the capacitance of one filter capacitor 23 is 20uF, two filter capacitors 23 can be connected in series to meet the required capacitance of the capacitor.

Specifically, the specific type of the filter capacitor 23 may be one of a chip capacitor, a film capacitor, a ceramic capacitor, and an electrolytic capacitor whose capacity is smaller than a preset threshold. When multiple filter capacitors 23 are set in the power adapter, the multiple filter capacitors 23 may use the same type of capacitor, or may use different types of capacitors.

The chip capacitor may refer to a multi-layer ceramic chip capacitor (Multi-layer Ceramic Capacitors, MLCC), wherein the MLCC is formed by stacking parallel ceramic materials and electrode materials. Film capacitors can be made of metal foil as electrodes, which are stacked with plastic films such as polyethylene, polypropylene, polystyrene or polycarbonate from both ends, and then rolled into a cylindrical capacitor.

In the case where the above-mentioned filter capacitor 23 is a chip capacitor or a film capacitor, if the capacity is smaller than the preset threshold, the volume of the capacitor can be reduced, thereby reducing the volume of the power adapter, and at the same time, the rectified AC current can be filtered. .

When the capacity of the filter capacitor 23 used is smaller than the preset threshold value, the filtering function of the filter capacitor 23 will be affected. It is larger, which is reflected in the unstable voltage after filtering. When the output voltage of the power conversion unit 20 is low and the load is large, the load will draw a large current from the power adapter. Due to the insufficient power stored in the filter capacitor 23, it is easy to cause the power adapter circuit system to collapse and not work continuously. , and even cause some parts to be damaged due to working under extreme conditions.

For example, the minimum operating voltage of the control chip in the power conversion unit 20 is 10V. Assuming that the transformer turns ratio is 8:1, then under normal circumstances, when the voltage on the primary side of the transformer is 220V, the voltage transmitted to the secondary side of the transformer is 27.5V , at this time, the power conversion unit 20 can work normally, and the energy from the primary side to the secondary side is 27.5V, the power conversion unit 20 can work normally, and when the voltage on the primary side of the transformer decreases, so that the voltage on the secondary side drops to 10V Below, the power conversion unit 20 cannot work normally.

FIG. 5 is a schematic diagram showing the relationship between the output current of the adapter and the time during the charging process under different filter capacitors 23 according to the embodiment of the present application. The curve 5-1 in the figure is the change curve of the output current and time of the adapter during the charging process when the filter capacitor 23 is an electrolytic capacitor with a capacity greater than the preset threshold; the curve 5-2 in the figure is that the filter capacitor 23 is a patch capacitor. Or the change curve of the output current and time of the adapter during the charging process in the case of the film capacitor or the electrolytic capacitor whose capacity is smaller than the preset threshold.

It can be seen from Figure 5 that the output current is a constant DC current by using an adapter with an electrolytic capacitor with a capacity greater than the preset threshold; using a chip capacitor or film capacitor or an electrolytic capacitor with a capacity smaller than the preset threshold to replace the capacitor with a capacity greater than the preset Threshold electrolytic capacitor, the current output by the adapter is a pulsating DC current, wherein the frequency of the pulsating DC current can be the same as the frequency of the mains.

In the embodiment of the present application, since the filter capacitor 23 adopts a chip capacitor or a film capacitor or an electrolytic capacitor whose capacity is less than the preset threshold value, the adapter outputs a pulsating DC current, which does not continuously charge the electronic device when charging the electronic device. The electronic device is charged with a large current, that is, after the electronic device is charged with a large current for a period of time, the current can be reduced or even stopped, thereby reducing the loss of the battery and further prolonging the service life of the battery.

When the AC power supply is unstable and other factors, the input terminal of the DC conversion circuit 201 will be lowered, and the input terminal of the DC conversion circuit 201 will be raised due to factors such as an increase in the charging voltage requested by the device to be charged. In these cases, the input terminal and the output terminal of the DC conversion circuit 201 may be greater than or equal to the first difference. At this time, the clamping unit 21 will send an adjustment signal to the DC conversion circuit 201 to reduce the chopper duty ratio of the switching unit in the DC conversion circuit 201, or stop the chopper, thereby realizing that the DC conversion circuit 201 outputs a lower voltage.

When the output voltage is low, the receiving voltage of the load terminal remains unchanged (such as charging the battery, the battery voltage can be considered constant in a short time), the difference between the output voltage of the power adapter and the load voltage decreases, and the path impedance Unchanged, according to Ohm's law I = △U/R, △U is smaller and I decreases. Therefore, the effect achieved by this solution is that when the difference between the input terminal and the output terminal of the DC conversion circuit 201 is lower than the first difference, the DC conversion circuit 201 reduces the output voltage (the limit is the voltage reduced to the load terminal), thereby reducing the power supply Adapter output current. Finally, it can be realized that when the input terminal of the DC conversion circuit 201 has a higher voltage, the power adapter finally outputs a larger current or a full load current, and when the voltage of the input terminal of the DC conversion circuit 201 is lower, the power adapter finally outputs a lower current or no output. current.

Please refer to FIG. 6 . FIG. 6 shows the input voltage and output voltage curves of the adapter after using the chopper unit according to an example. In FIG. 6 , the solid line represents the input terminal voltage of the DC conversion circuit 201 , and the dotted line represents the output terminal voltage of the DC conversion circuit 201 . It can be seen that, under the action of the clamping unit 21, the output end of the DC conversion circuit 201 is clamped within a certain range. When the voltage difference between the input terminal and the output terminal of the DC conversion circuit 201 is lower than the first difference, the output terminal voltage of the DC conversion circuit 201 is clamped to a low value. A voltage equivalent to the battery voltage of the charging device.

In one embodiment, when the difference between the voltage of the first input terminal and the voltage of the second input terminal is greater than or equal to the first difference, the output terminal of the clamping unit outputs a control signal to the The feedback end of the control circuit controls the power conversion unit to lower the output voltage, so that the output voltage of the power adapter is not less than the voltage of the unit to be charged; wherein, during the charging process, the battery to be charged is connected to the power source output of the adapter. In this way, the voltage of the unit to be charged is prevented from being higher than the output end of the power adapter, which causes current backflow. The unit to be charged may be a battery to be charged, or a battery pack to be charged.

It should be understood that, during the charging process, the battery to be charged is connected to the output end of the power adapter. "Voltage of the battery to be charged/battery pack" should be understood as the voltage value detected at both ends of the battery to be charged/battery pack at the moment when the power conversion unit adjusts the output voltage.

The control circuit 202 may specifically be a chip, for example, a dedicated AC-DC power management chip 2021 has a switch control terminal, a feedback terminal FB, and a power supply terminal; the feedback terminal is used to control the chopper duty cycle of the switching unit in the DC conversion circuit 201, Thus, the purpose of regulating the output voltage of the DC conversion circuit 201 is achieved.

The above-mentioned first difference represents the voltage difference between the input terminal and the output terminal of the DC conversion circuit 201 . When the voltage difference is too large and reaches the first difference, it means that the power input at the input terminal will no longer be able to support the voltage output at the output terminal. circuit safety.

The setting of the first difference can be set in combination with the accommodation size of the filter capacitor 23 , the minimum operating voltage of the control circuit 202 , and the minimum driving voltage of the switch unit in the DC conversion circuit 201 .

The setting of the clamping unit 21 enables the output voltage of the power adapter to be correspondingly increased when the voltage output by the DC conversion circuit 201 is relatively high, and the output voltage of the power adapter is also correspondingly decreased when the output voltage of the DC conversion circuit 201 is relatively low. Therefore, the power adapter circuit will not collapse due to the excessive current drawn by the load, so that the entire power adapter circuit is resistive, and the safety of the power adapter operation is ensured.

It should be noted that, in this embodiment, a filter capacitor 23 with a smaller capacitance value is used to cooperate with the clamping unit 21, so as to achieve the above result of improving the safety of the power adapter operation. Reference is made here to the adapter circuit architecture in FIG. 2 .

In the case where a filter capacitor 23 with a smaller capacitance value is used on the primary side of the transformer, the filter capacitor 23 with a smaller capacitance value has a smaller capacitive reactance to the input current. In addition, the pulsating DC frequency rectified by the rectifier circuit 22 will double (to reach HZ), and the inductance of the primary side winding of the transformer is very small relative to the pulsating DC, and can be ignored, so the AC power after rectification The waveform input to the primary side of the transformer is a relatively complete and regular-shaped steamed bun wave, which does not show obvious phase lag. Therefore, the power factor of the power adapter circuit in the present disclosure is relatively high, close to 1. Furthermore, the present disclosure further sets the clamping unit 21 to make the load of the power adapter appear resistive, so as to achieve the effect that the voltage of the output terminal of the power adapter and the voltage of the input terminal of the power adapter change synchronously, so that when the voltage of the input terminal of the power adapter is higher than When the voltage is low, the power adapter circuit will make the output voltage of the DC conversion circuit 201 correspondingly lower under the action of the clamping voltage, thereby avoiding the extreme situation of some components caused by the power adapter circuit needing to output high voltage. This in turn leads to a situation where the power adapter circuit collapses.

In the above-mentioned embodiment, it is mentioned that when the difference between the voltage of the first input terminal and the voltage of the second input terminal is greater than or equal to the first difference, the output terminal of the clamping unit 21 outputs a control signal to the control circuit 202 to cut down the wave duty cycle or stop chopping. Here, the duty cycle can be lowered to a fixed value, or the output voltage can be stopped directly, and the voltage output can be performed after the input voltage of the power adapter is stabilized. It is reflected in the charging process, the charging speed is slow in a certain period of time, or the charging is stopped, but this period is usually very short, and it will not have a significant impact on the overall charging speed, but it has a great effect on the work safety protection of the power adapter. significant.

In another embodiment, the control circuit 202 is further configured to control the decreasing amplitude of the chopper duty cycle of the DC conversion circuit 201 according to the difference between the voltage of the first input terminal and the voltage of the second input terminal. Illustratively, a table of correspondences between the difference between the voltage at the first input terminal and the voltage at the second input terminal and the amplitude reduction of the chopper duty cycle of the DC conversion circuit 201 can be made in a test environment. The greater the difference between the voltage of the first input terminal and the voltage of the second input terminal, the greater the decreasing amplitude of the chopper duty cycle.

Please refer to FIG. 7 , which is a circuit block diagram of a power adapter according to an example. There can be various specific forms of the architecture of the power adapter circuit of the present disclosure. In one embodiment, the DC conversion circuit 201 includes a power transformer 201, and the control circuit 202 is connected to the primary winding of the power transformer 201 to regulate the chopping frequency of the pulsating DC power on the primary winding; the primary side of the power transformer 201 is connected to the clamping The first input terminal of the unit 21 is connected, and the secondary winding of the power transformer 201 is connected to the second input terminal of the clamping unit 21 . In this embodiment, the DC conversion is performed on the primary side of the power transformer 201 .

The power transformer 201 can be a forward transformer, and the forward transformer has lower requirements on the inductance of the transformer, which can further reduce the volume of the adapter.

In this embodiment, the control circuit 202 may specifically be a chip, such as a dedicated AC-DC power management chip 2021 . The AC-DC power management chip 2021 integrates a switch tube that is electrically connected to the primary winding of the power transformer 201 and a drive circuit that drives the switch tube to be turned on and off. By controlling the turn-on or turn-off of the switch tube, the timing of transmitting electrical energy from the primary winding of the transformer to the secondary winding is controlled. The frequency of the switching tube is relatively high (usually above k), so through the rapid switching of the switching tube, the voltage on the primary coil of the power transformer 201 presents a pulsed square wave. The secondary winding of the power transformer 201 outputs a constant voltage, and the specific voltage value is determined by the frequency of the output signal of the SW terminal on the AC-DC power management chip 2021 . In another embodiment, the switch can also exist independently of the AC-DC power management chip 2021 .

The output terminal of the clamping unit 21 is connected to the feedback terminal of the AC-DC power management chip 2021 . Illustratively, when the output terminal of the clamping unit 21 outputs a high level, it interferes with the feedback terminal FB of the AC-DC power management chip 2021, so that the switching AC-DC power management chip 2021 outputs a low duty cycle PWM or stops outputting PWM, thereby realizing The DC conversion circuit 201 outputs a lower voltage.

Please refer to FIG. 8 , which is a circuit block diagram of a power adapter according to another example. In this embodiment, there is another implementation. Specifically, the adapter circuit also has a protocol chip 24 connected to the secondary winding of the power transformer 201, and the protocol chip 24 has a feedback terminal; the protocol chip 24 is connected in communication with the AC-DC power management chip 2021; the output terminal of the clamping unit 21 is connected to The feedback terminal of the protocol chip 24 is connected to trigger the protocol chip 24 to output a feedback signal to the AC-DC power management chip when the difference between the voltage of the primary winding of the power transformer 201 and the voltage of the secondary winding is greater than or equal to the first difference 2021, so that the AC-DC power management chip 2021 adjusts the duty cycle of the output PWM wave.

The protocol chip 24 is used to shake hands with the device to be charged to obtain the charging power requested by the device to be charged. The protocol chip 24 can also communicate with the AC-DC power management chip 2021, so that the AC-DC power management chip 2021 can control the switch The switching frequency of the control terminal is adjusted to adjust the output voltage of the secondary side of the power transformer 201 .

Please refer to FIG. 9 , which is a circuit block diagram of a power adapter according to another example. In another embodiment, the power adapter further includes a transformer 25 , and the DC conversion circuit 201 is connected to the secondary winding of the transformer 25 for chopping the DC pulsating power on the secondary winding of the transformer 25 . In this embodiment, the DC conversion is performed on the secondary side of the transformer 25 .

The pulsating DC output from the secondary side of the transformer 25 is converted into a pulsating DC of another voltage level after passing through the DC conversion circuit 201 , which can then be filtered by the filter capacitor 23 to smooth the waveform.

In this embodiment, the first input end of the clamping unit 21 is connected to the output end of the transformer 25 , and the second input end of the clamping unit 21 is connected to the output end of the DC conversion circuit 201 .

Based on the embodiment of FIG. 9 , please refer to FIG. 10 , which is a circuit block diagram of a power adapter according to another example. The power adapter also includes a power management chip 26; the power management chip 26 is connected to the primary winding of the transformer 25 to control the power chopper on the primary winding of the transformer 25; the output end of the clamping unit 21 and the feedback end of the power management chip 26 connect.

Please refer to FIG. 11 and FIG. 12 , FIG. 11 is a circuit diagram of a chopper unit according to an example;

FIG. 12 is a partial circuit diagram of a power adapter according to an example. In an embodiment of the clamping unit 21 , the clamping unit 21 includes a voltage divider circuit and a switch tube; the voltage divider circuit is used to adjust the voltage between the first input terminal Vin1 and the second input terminal Vin2 of the clamping unit 21 The difference is divided, and the divided voltage is input to the controlled end of the switch tube.

The voltage divider circuit can be a resistor divider circuit. For example, the voltage divider circuit includes a first resistor R1 and a second resistor R2. The first end of the first resistor R1 is connected to the first input end Vin1, and the second end of the first resistor R1 is connected to the first input end Vin1. The controlled end of the switch tube is connected, the first end of the second resistor R2 is connected to the second end of the first resistor R1, and the second end of the second resistor R2 is connected to the second input end Vin2 of the clamping unit 21; the switch tube The first end of the switch is connected to the second input end Vin2 , and the second end of the switch is connected to the control circuit 202 .

Wherein, the switch tube can be a transistor Q1 or a MOS tube. Illustratively, when the switch is a P-type transistor Q1. The first end of the switch is the emitter of the transistor Q1, the second end of the switch is the collector of the transistor Q1, and the controlled end of the switch is the gate of the transistor Q1.

When the voltage difference between the first input terminal Vin1 and the second input terminal Vin2 is divided by the first resistor R1 and the second resistor R2, the voltage between the emitter and the gate of the switch is greater than the switch on voltage (such as silicon diode D10.7V), the switch is turned on at this time. The output terminal Vout of the clamping unit 21 is output to the feedback terminal of the control circuit 202 through the second terminal of the switch tube.

Specifically, in FIG. 12 , the output terminal Vout of the clamping unit 21 is connected to the protocol chip 24 on the secondary side of the transformer. The protocol chip 24 further sends the signal fed back by the output terminal Vout of the clamping unit 21 to the feedback terminal of the AD-DC power supply control chip on the primary side of the transformer through the isolation unit.

Further, the clamping unit 21 further includes a protection circuit, and the protection circuit is connected between the first input terminal Vin1 and the second input terminal Vin2 of the clamping unit 21 to limit the distance between the controlled terminal and the first terminal of the switching tube Q1 voltage.

Specifically, the third circuit includes a diode D1 and a third resistor R3, the first end of the third resistor R3 is connected to the controlled end of the switch tube, the second end of the third resistor R3 is connected to the anode of the diode D1, and the The cathode is connected to the first end of the switch tube.

Further, the clamping unit 21 may further include a fourth resistor R4, and the fourth resistor R4 is connected in series between the second end of the switch tube and the feedback end of the control circuit 202, so as to perform current limiting protection on the second end of the switch tube Q1 .

Based on the above embodiment, in one embodiment, the operating frequency of the DC conversion circuit 201 can be increased, thereby increasing the operating frequency and reducing the requirement for the inductance of the transformer, thereby reducing the requirement for the volume of the transformer to further reduce the volume of the power adapter.

In an example, the switching frequency of the switching tube used for chopping in the power conversion unit 20 is greater than or equal to 300KHz. Specifically, GaN switches can be used. At least four GaN switches form a GaN full-bridge circuit; the first end of the GaN full-bridge circuit is connected to the AC power supply, and the second end of the GaN full-bridge circuit is connected to the primary winding of the transformer.

In this embodiment, the rectifier circuit may be located on the primary side of the transformer or on the secondary side of the transformer.

In this embodiment, a high-speed electronic switch is used for chopping in the power conversion unit 20, so that the chopping frequency can be increased, thereby reducing the volume of devices related to energy conversion, thereby reducing the overall power adapter. volume.

When a high-speed electronic switch is used for chopping, the transformer can use fewer turns. When the number of turns of the transformer is reduced, the transformer's transformation ratio will be larger; that is, the voltage variation range on the secondary winding L2 of the transformer will be wider. Moreover, when using a printed circuit PCB type transformer, the multi-layer PCB board is sandwiched between the magnetic cores. During the production process, the air gap is not easy to control, so it is easy to cause the actual transformation ratio of the PCB transformer to be compared with the design transformation ratio. There is a deviation between the two, and this deviation may cause the voltage range on the secondary winding of the transformer to increase further.

The clamping unit 21 in the power adapter of the present disclosure can well protect the power adapter against the situation that the voltage amplitude on the secondary winding of the transformer changes greatly. When the voltage on the secondary winding of the transformer is relatively small, the clamping unit 21 can correspondingly reduce the output voltage of the power adapter, thereby protecting the working stability of the power adapter.

A feedback circuit can also be set in the power adapter circuit, and the feedback circuit is used to establish feedback between the transformer winding voltage and the AC-DC power management chip 2021, so that the AC-DC power management chip 2021 can adjust the switching frequency of the switching tube, so as to achieve a The purpose of secondary output voltage stabilization. In one embodiment, a separate winding is set on the primary coil side of the transformer as a feedback winding, the output switching waveform is modulated, and feedback is obtained from a separate winding. In another embodiment, a resistor is used to divide the voltage on the secondary output side, and a voltage feedback signal is sent back through a comparator, a resistor and an optocoupler.

While the present disclosure has been described with reference to several exemplary embodiments, it is to be understood that the terminology used is of description and illustration, and not of limitation. Since the present disclosure can be embodied in many forms without departing from the spirit or spirit of the invention, it is to be understood that the above-described embodiments are not limited to any of the foregoing details, but are to be construed broadly within the spirit and scope defined by the appended claims Therefore, all changes and modifications that come within the scope of the claims or their equivalents should be covered by the appended claims.

Claims

A power adapter, characterized in that it includes:

The power conversion unit is used for AC-DC conversion of AC power, or for DC-DC conversion of pulsating DC power formed by rectifying the AC power;

a clamping unit, connected to the input terminal and the output terminal of the power conversion unit, to control the power conversion unit when the difference between the input terminal voltage and the output terminal voltage of the power conversion unit is greater than or equal to a first difference The unit reduces the output voltage.
The power adapter according to claim 1, wherein the power conversion unit comprises a DC conversion circuit and a control circuit for controlling the chopping frequency of the DC conversion circuit; the DC conversion circuit is used to convert the rectified AC power chopping;

The clamping unit has a first input end, a second input end and an output end; the control circuit has a feedback end; the first input end of the clamping unit is connected with the input end of the DC conversion circuit, the The second input end of the clamping unit is connected with the output end of the DC conversion circuit; the output end of the clamping unit is connected with the control circuit;

When the difference between the voltage of the first input end and the voltage of the second input end is greater than or equal to the first difference, the output end of the clamping unit outputs a control signal to the feedback end of the control circuit, To trigger the control circuit to lower the duty ratio of the output PWM wave or stop the output of the PWM wave.
The power adapter according to claim 2, wherein the control circuit is further configured to control the DC conversion circuit according to the magnitude of the difference between the voltage of the first input terminal and the voltage of the second input terminal. Decrease the amplitude of the duty cycle of the output PWM wave.
The power adapter according to claim 2, wherein when the difference between the voltage of the first input terminal and the voltage of the second input terminal is greater than or equal to the first difference, the clamping unit has a The output terminal outputs a control signal to the feedback terminal of the control circuit, and controls the power conversion unit to lower the output voltage, so that the output voltage of the power adapter is not less than the voltage of the unit to be charged; wherein, during the charging process, the The unit to be charged is connected to the output end of the power adapter.
The power adapter according to claim 2, wherein the DC conversion circuit comprises a power transformer, and the control circuit is an AC-DC power management chip; the AC-DC power management chip and the primary of the power transformer winding connections for chopping electrical energy on the primary winding;

The primary winding of the power transformer is connected to the first input terminal of the clamping unit, and the secondary winding of the power transformer is connected to the second input terminal of the clamping unit.
The power adapter according to claim 5, wherein the power adapter further has a protocol chip connected to the secondary winding of the power transformer, the protocol chip has a feedback end; the protocol chip is connected to the AC -DC power management chip communication connection;

The output end of the clamping unit is connected to the feedback end of the protocol chip, so that when the difference between the voltage of the primary winding of the power transformer and the voltage of the secondary winding is greater than or equal to the first difference, the The protocol chip outputs a feedback signal to the AC-DC power management chip, so that the AC-DC power management chip reduces the duty ratio of the output PWM wave.
The power adapter of claim 5, wherein the power transformer comprises a forward transformer.
The power adapter according to claim 2, wherein the power adapter further comprises a transformer, and the DC conversion circuit is connected to the secondary winding of the transformer, and is used for outputting electric energy from the secondary winding of the transformer chopping;

The first input end of the clamping unit is connected to the secondary winding of the power transformer, and the second input end of the clamping unit is connected to the output end of the DC conversion circuit.
The power adapter according to claim 8, characterized in that, the power adapter further comprises a power management chip; the power management chip is connected to the primary winding of the transformer to control the chopping of the electric energy on the primary winding. Wave;

The output end of the clamping unit is connected to the feedback end of the power management core.
The power adapter according to claim 2, wherein the clamping unit comprises a voltage divider circuit and a switch tube; the voltage divider circuit is used to connect the first input end and the second input end of the clamping unit The voltage difference between them is divided, and the divided voltage is input to the switch tube.
The power adapter according to claim 10, wherein the voltage dividing circuit comprises a first resistor and a second resistor, a first end of the first resistor is connected to the first input end, and the first resistor The second end of the resistor is connected to the controlled end of the switch tube, the first end of the second resistor is connected to the second end of the first resistor, and the second end of the second resistor is connected to the clamp the second input terminal of the bit cell is connected;

The first end of the switch tube is connected to the second input end, and the second end of the switch tube is connected to the control circuit.
The power adapter according to claim 11, wherein the clamping unit further comprises a protection circuit, and the protection circuit is connected between the controlled end and the first end of the switch tube to limit the switch The voltage between the controlled end and the first end of the tube.
The power adapter according to any one of claims 1 to 12, characterized in that, the power adapter further comprises a filter capacitor, and the capacitance value of the filter capacitor is smaller than a preset capacitance value, which is used for rectifying the rectified AC power or The electric energy output by the DC electric energy conversion unit is filtered.
The power adapter according to claim 13, wherein the filter capacitor comprises at least one first filter capacitor, and the at least one first filter capacitor is connected to the input end of the power conversion unit for rectifying the rectified The AC power is filtered to output pulsating DC power.
The power adapter according to claim 13, wherein the filter capacitor comprises at least one second filter capacitor, and the at least one second filter capacitor is connected to the output end of the power conversion unit, and is used for the The power output by the DC power conversion unit is filtered.
The power adapter according to claim 13, wherein the filter capacitor comprises one or more of a chip capacitor, a film capacitor, a ceramic capacitor, and an electrolytic capacitor whose capacity is smaller than the preset threshold.
The power adapter according to claim 1, wherein the power conversion unit comprises one or more cascades of a rectifier bridge circuit, a buck circuit, a boost circuit, a buck-boost circuit, and a charge pump circuit.
The power adapter according to claim 1, wherein the switching frequency of the switching tube used for chopping or commutation in the power conversion unit is greater than or equal to 300KHz.
The power adapter of claim 1, further comprising:

a charging interface for connecting the device to be charged to charge the device to be charged;

The power adapter also communicates with the device to be charged through the charging interface.
A mobile power supply, characterized in that it includes a power adapter; the power adapter includes:

The power conversion unit is used for AC-DC conversion of AC power, or for DC-DC conversion of pulsating DC power formed by rectifying the AC power;

a clamping unit, connected to the input terminal and the output terminal of the power conversion unit, to control the power conversion when the difference between the input terminal voltage and the output terminal voltage of the power conversion unit is greater than or equal to the first difference The unit reduces the output voltage.