CN212183413U - High-efficient charging power supply based on E type gallium nitride switching device - Google Patents

Abstract

The utility model discloses a high-efficient charging source based on E type gallium nitride switching device, including flyback switch circuit and drive protection circuit, wherein, flyback switch circuit includes flyback transformer, E type gallium nitride switching device and absorption circuit, and drive protection circuit includes steady voltage source and diode; the E-type gallium nitride switching device is in a conducting state when the gate control voltage is positive, and is cut off when the gate control voltage is zero; the cathode of a diode in the drive protection circuit is connected with a voltage stabilizing source, the anode of the diode is connected with the gate electrode of the E-type gallium nitride switching device, and the diode is used for clamping the gate electrode voltage of the E-type gallium nitride switching device at a safe voltage level through the voltage stabilizing source. The utility model discloses when using the E type gallium nitride device as the power switch device in the flyback circuit, improve the turn-off bias voltage that drives protection circuit and come control power switch in the flyback circuit, both reduced switching loss, improved circuit stability again.

Description

High-efficient charging power supply based on E type gallium nitride switching device

Technical Field

The utility model relates to a power field, in particular to high-efficient charging source based on E type gallium nitride switching device.

Background

With the increasing miniaturization of electronic products, portable electronic devices such as smart phones and portable computers are more and more widely used in people's lives, and each portable electronic device needs to be equipped with a battery charger. Due to the differences in battery capacities of various portable electronic devices and the incompatibility of charging interfaces, almost everyone or every household needs to have a plurality of different chargers, and since the efficiency and power density of the old generation chargers are low, the size and weight of the chargers are large, the charging speed is slow, which is a phenomenon that needs to be improved with the advancement of technology.

A new generation of fast charging power sources has started to be gradually brought to the market with the development of power electronics and information technology. The new generation of fast charging source adopts more advanced power electronic devices such as gallium nitride devices and the like, so that the switching frequency can be higher, the conversion efficiency is higher, the size and the weight of the charger can be greatly reduced, higher power can be provided, and the charging speed is accelerated. Meanwhile, various portable electronic devices gradually adopt unified charging interfaces and intelligent charging functions, and one compact quick charging source can charge various portable electronic devices, so that great convenience is provided for charging requirements.

Meanwhile, as the fast charging source is increasingly competitive in terms of volume, weight, performance and the like, the design is more challenging. In order to reduce the size and increase the switching frequency and the conversion efficiency of the power supply with power density, the power supply needs to be improved at the same time, and excellent performance indexes such as working temperature and electromagnetic interference are ensured. Because the switching loss of the power supply is in direct proportion to the switching frequency under normal conditions, especially when a flyback circuit topology is adopted, the leakage inductance loss of the isolation transformer is often larger than the loss of the power switching device in the high-frequency switching operation process, and the loss causes the efficiency of the power supply to be in a descending trend along with the increase of the switching frequency, so that the overheating of the power device and the whole product is further caused, and how to maintain the high efficiency while improving the switching frequency becomes a challenge of the design of a new generation of quick-charging power supply. In addition, since the new generation of fast charging power supplies are required to meet the battery charging requirements of all portable electronic devices, the output voltage range is very wide, the range of 5V to 20V needs to be covered at least, and the load current variation range is also very wide, how to maintain the optimum power supply efficiency and reliable operation of power devices in such a situation is also a challenging design issue. On the other hand, because the space design of the new generation of fast charging source is very compact, the electromagnetic interference coupling between components and wires is relatively strong, so that the design of electromagnetic compatibility is more challenging.

SUMMERY OF THE UTILITY MODEL

In order to overcome the not enough of prior art existence, the utility model provides a high-efficient charging source based on E type gallium nitride switching device reduces the consumption in the power operation, realizes high efficiency operation when realizing high power density, reduces the electromagnetic interference coupling to guarantee the reliability of power device work, technical scheme is as follows:

the utility model provides a high-efficient charging source based on E type gallium nitride switching device, including flyback switch circuit and drive protection circuit, wherein, flyback switch circuit includes flyback transformer, E type gallium nitride switching device and absorption circuit, drive protection circuit includes steady voltage source and diode;

the E-type gallium nitride switching device is in a conducting state when the gate control voltage is positive, and is cut off when the gate control voltage is zero;

and the diode in the drive protection circuit is connected with the voltage stabilizing source at the cathode and connected with the gate electrode of the E-type gallium nitride switching device at the anode, and is used for clamping the gate electrode voltage of the E-type gallium nitride switching device at a safe voltage level through the voltage stabilizing source.

Further, the driving protection circuit further comprises a voltage stabilizing diode, and the voltage stabilizing diode is connected with the diode in series to increase the clamping voltage of the gate electrode of the E-type gallium nitride switching device.

Optionally, the wires wound by the primary winding and the secondary winding of the flyback transformer are single-stranded flat wires, and the primary winding and the secondary winding are wound in a multi-layer overlapping manner.

Preferably, the primary winding and the secondary winding of the flyback transformer are wound side by using multi-strand wires and are wound in a plurality of layers overlapping with each other.

Further preferably, the wire is a flat wire.

Furthermore, the alternating current input end of the flyback transformer comprises an integrated alternating current input circuit board and a power supply main circuit board, and an alternating current input plug and a filter network for suppressing electromagnetic interference are arranged on the integrated alternating current input circuit board;

and the filter network on the integrated alternating current input circuit board is electrically connected with the power main circuit on the power main circuit board through welding.

Preferably, the filter network further comprises a front-end capacitor, and the front-end capacitor is directly connected across the port of the ac input plug.

The utility model provides a beneficial effect that technical scheme brought as follows:

a. a flyback circuit is adopted, so that the power supply is compact in structure;

b. the E-type gallium nitride device is used as a power switch device in the flyback circuit, so that the switching loss is reduced, and the circuit efficiency is improved;

c. a driving protection circuit in the flyback circuit is improved to control the turn-off bias voltage of the power switch, so that the circuit stability is improved;

d. the winding mode of the lead of the transformer winding is improved, so that the leakage inductance is effectively reduced, and the skin effect is reduced;

e. the structural design of the alternating current input end is improved, electromagnetic interference is reduced, and meanwhile, the whole power supply structure is more compact and tidy.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

Fig. 1 is a circuit diagram of a flyback switching circuit using an E-type gan switching device according to an embodiment of the present invention;

fig. 2-1 is a circuit diagram of a driving protection circuit added based on the flyback switch circuit in fig. 1 according to an embodiment of the present invention;

fig. 2-2 is a circuit diagram of a further improvement of the drive protection circuit of the flyback switch circuit of fig. 2-1;

fig. 3-1 is a schematic diagram of a winding-wound wire of a flyback transformer in the prior art;

fig. 3-2 is a schematic diagram of a winding structure wound side by using multiple strands of wires according to an embodiment of the present invention;

3-3 are schematic diagrams of winding structures wound by single-stranded flat wires according to embodiments of the present invention;

FIG. 4-1 is a schematic diagram of an AC inlet line connection design in the prior art;

fig. 4-2 is a schematic view of an ac incoming line connection design structure provided by the embodiment of the present invention.

Wherein the reference numerals include: 1-integrated AC input circuit board, 11-AC input plug, 12-filter network, 13-front end capacitor, 2-power main circuit board, 21-power main circuit board and 3-flexible lead.

Detailed Description

In order to make the technical field person understand the present invention better, and to understand the objects, technical solutions and advantages thereof more clearly, the embodiments of the present invention are described in detail below with reference to the accompanying drawings. It should be noted that the implementations not shown or described in the drawings are in a form known to those of ordinary skill in the art. Additionally, while exemplifications of parameters including particular values may be provided herein, it is to be understood that the parameters need not be exactly equal to the respective values, but may be approximated to the respective values within acceptable error margins or design constraints. It is obvious that the described embodiments are only some of the embodiments of the present invention, and not all of them. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts shall belong to the protection scope of the present invention. In addition, the terms "comprises" and "comprising," and any variations thereof, in the description and claims of the present invention, are intended to cover a non-exclusive inclusion, such that a process, method, apparatus, product, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, product, or apparatus.

In an embodiment of the present invention, a high-efficiency charging power supply based on an E-type gallium nitride switch device is provided, including a flyback switch circuit and a driving protection circuit, wherein the flyback switch circuit includes a flyback transformer, a power switch and an absorption circuit for suppressing voltage overshoot and oscillation, and the power switch includes a gallium nitride switch device; the driving protection circuit comprises a voltage stabilizing source and a diode used for connecting the voltage stabilizing source and the power switch. Specifically, the snubber circuit is preferably an RCD snubber circuit, and as shown in fig. 1-2, a diode D1 is connected in series with a resistor R1, and a capacitor C1 is connected in parallel with the resistor R1 to form the snubber circuit.

The embodiment of the utility model provides a power conversion main circuit that adopts quasi-resonant flyback switch circuit, and this kind of circuit topology power components and parts are minimum, are favorable to compact power supply design, and material cost is also minimum, is a better selection in the design of quick charge source. However, as is known, the switching loss of the flyback switching circuit is relatively large, and the electromagnetic interference generated by the voltage overshoot during the switching operation is also relatively high, which is a great challenge to the design requirement of high efficiency and low noise interference.

The switching loss of the operation of the flyback switching circuit mainly comprises two parts, one part is the switching loss of the power switch, and the other part is the switching loss formed by the leakage inductance of the primary winding of the transformer. Because the electromagnetic energy stored in the primary leakage inductance during the flyback operation cannot be transferred to the secondary to form an effective output, and a strong voltage overshoot and oscillation can be formed when the power switch is turned off, the power switch can be in an overvoltage state in severe cases, and meanwhile, the switching loss is increased and strong electromagnetic interference is generated. In order to reduce this effect, the flyback circuit except for the active clamp flyback circuit (which needs to use two power switches and a suspension driving circuit, and is higher in cost and thus out of the consideration of the present invention) needs to use an absorption circuit to suppress the voltage overshoot and oscillation, the absorption strength of the absorption circuit is determined by the size of the leakage inductance energy storage, the more the leakage inductance energy storage, the higher the absorption strength, but the larger the power consumption caused by the leakage inductance energy storage, the RCD absorption circuit is only one of the conventional circuits of the absorption circuit, and other absorption circuits, such as an RC absorption circuit, can also be used.

In view of the switching loss of the power switch in the first part, one of the measures of reducing the switching loss of the embodiment of the present invention is to use a power switch device with excellent performance and relatively small switching loss, and as shown in fig. 1, the power switch device (hereinafter referred to as Q1) is an E-type gallium nitride switch device. In fig. 1, the E-type power switch also has the advantages of low switching loss and high operating frequency, and can be used in the design scheme of the present invention without affecting the essential technical features of the present invention, when using the E-type gallium nitride switch device, because its positive gate voltage is turned on, the characteristic that the zero gate voltage is turned off can be directly driven by the positive voltage driving circuit, without using the series MOSFET, as shown in fig. 1.

During the off period of operation of the circuit shown in fig. 1, the negative bias voltage at the gate of Q1 may exceed the safe breakdown voltage between the gate and the source to cause over-voltage breakdown damage, or may drop below the threshold off voltage at the gate of Q1 due to the discharge of leakage current, thereby causing Q1 to turn on and further causing damage or failure to the circuit. The following circuit design is one of the utility model points, and this problem can be solved very reliably. The details are as follows:

an example of using an E-type gallium nitride switching device is shown in fig. 2-1. It is known that the gate of an E-type gan device is very sensitive to the driving voltage, which needs to be higher than 5V to ensure full conduction, but there is a risk of overvoltage breakdown when the gate voltage is higher than 7V, so that the gate overvoltage is easily caused by parasitic oscillation generated by the parasitic inductance of the driving circuit and the gate input capacitance of the gan device during actual operation, especially in the case of high frequency switching operation. In the circuit example shown in fig. 2-1, the anode of the clamping diode is directly connected to the gate of the E-gan switch Q1, and the gate voltage of Q1 is stably clamped at a safe level by the voltage source V1, i.e., the gate voltage of the E-gan switching device is clamped at a safe voltage level, i.e., a voltage level that excludes the risk of voltage breakdown of the power device.

In practical applications, the clamping voltage source does not need to be specially arranged, and the voltage range of the auxiliary power supply such as a control circuit or a driving circuit in the system is mostly in the required clamping voltage range. If the voltage of the clamping voltage source is below the desired clamping voltage range, a device with a constant voltage drop, such as a zener diode, may be connected in series with D2 to increase the clamping voltage to within the desired clamping voltage range, as illustrated in fig. 2-2. In the above method of using the auxiliary power supply as the clamping voltage source, a part of energy of the power switch device during the turn-off process is coupled to the auxiliary power supply to be reused, rather than being consumed in the circuit in vain, so that the efficiency of the power supply is further improved.

As mentioned above, another important factor affecting efficiency in flyback circuits is the switching losses created by the leakage inductance of the transformer windings. As mentioned above, the electromagnetic energy stored in the transformer leakage inductance during switching cannot be coupled to the secondary to generate effective output power, but is consumed in the circuit wastefully, and the absorption circuit for suppressing the voltage overshoot caused by the leakage inductance energy also consumes another part of extra energy besides the leakage inductance energy, so besides using the costly active clamp flyback circuit, the most effective method for further improving efficiency in the low-cost solution is to reduce the leakage inductance of the transformer as much as possible. The embodiment of the utility model provides a flyback switching circuit to having E type gallium nitride switching device all can adopt the structure of optimizing flyback transformer's winding wire to further restrain electromagnetic interference:

in the conventional flyback transformer manufacturing method in the prior art, the primary winding and the secondary winding of the transformer are usually wound by adopting a multi-layer mutual overlapping method, so that the leakage inductance of the transformer can be effectively reduced, and the wires for winding the primary winding and the secondary winding usually use single-stranded round insulating wires, as shown in fig. 3-1; in an embodiment of the present invention, the primary winding and the secondary winding of the flyback transformer are both wound side by using multiple strands of wires, as shown in fig. 3-2, and the primary winding and the secondary winding are wound in a multi-layer overlapping manner, and the arrow in fig. 3-2 indicates that the winding uses a round multiple strand formed by twisting three strands of thin wires, such a winding structure can generally control the leakage inductance of the transformer to be about 3% of the main inductance, and the actual effect may vary with other factors, such as the magnetic core air gap of the transformer, the geometry of the winding, and the like. The method has the following advantages:

firstly, the whole conductor is in a flat shape due to the multi-strand side-by-side structure of the winding lead, the primary winding and the secondary winding are attached to each other more tightly when being wound in an overlapping mode, and the space of a non-conductor between the primary winding and the secondary winding is smaller, so that the leakage inductance is reduced more effectively;

secondly, according to the actual required total cross section area of the conductor and the actual size of the coil framework, the multi-strand parallel lead can select different combinations of single-strand wire diameter and strand number, so that each layer of the winding can be wound completely according to the number of layers determined by the number of turns, and the structure can enable the electromagnetic coupling between the primary winding and the secondary winding to reach the maximum degree, thereby reducing the leakage inductance to the maximum degree;

thirdly, using multiple wires side by side, with a given total cross section of the wire, the wire diameter of each single wire is naturally reduced accordingly, which is also just favorable for reducing the high frequency skin effect of the wire.

In practical application, the transformer wound by the method can control leakage inductance to be below 1%, so that conversion efficiency of the power supply is greatly improved, and meanwhile, as voltage overshoot and parasitic oscillation are reduced along with reduction of the leakage inductance, switching loss and electromagnetic interference radiation of the power switch are correspondingly reduced, so that the working performance of the power supply is better.

The above-mentioned method of arranging the plurality of strands of wires side by side can be further modified to use a single-stranded flat wire (as shown in fig. 3-3) or a multi-stranded flat wire (not shown) for winding, which can increase the electromagnetic coupling between the primary and secondary windings, reduce the leakage inductance, and effectively reduce the high-frequency skin effect.

In the design of the compact quick charging source, because the distance between components, wires and the like is very close, the coupling of electromagnetic interference, particularly the coupling through space, is stronger, and the difficulty of meeting the requirement of electromagnetic compatibility is increased for the design. Although various measures can be adopted in circuit design and structural design to reduce the strength of a radiation source, reduce coupling, enhance filtering and the like, a connection scheme of a lead adopted by a PCB alternating current incoming line design of a power supply still has a link of electromagnetic interference coupling which needs to be effectively suppressed. Referring to fig. 4-1, in the ac incoming line connection design in the prior art, an ac input plug 11 and a main power supply circuit board 2 are separated from each other, and are connected by using two flexible wires 3, and for convenience of assembly and disassembly, the wires 3 have a sufficient length, which usually needs about 40 mm. When the ac input plug and the circuit board are assembled together, the flexible conductor 3 and the ac input plug can sense a part of electromagnetic radiation by being very close to a strong electromagnetic radiation source such as a power switching device and a transformer on the circuit board. Because the high-frequency filter network of the power input end is installed on the circuit board, the induced high-frequency electromagnetic interference signal can reach the high-frequency filter network on the circuit board from the alternating current input plug by passing through the flexible lead 3 and the conductor path on the circuit board, so that a part of the induced high-frequency electromagnetic radiation signal can not be effectively filtered and is transmitted to the alternating current power supply end through the alternating current input plug, and the electromagnetic interference radiation degree and the electromagnetic compatibility standard reaching difficulty are increased.

In an embodiment of the present invention, there is provided a flyback switching circuit having an E-type gallium nitride switching device, which can adopt a structure of optimizing an ac input terminal to further suppress electromagnetic interference, as shown in fig. 4-2:

the alternating current input end of the flyback transformer comprises an integrated alternating current input circuit board 1 and a power supply main circuit board 2, an alternating current input plug 11 and a filter network 12 for suppressing electromagnetic interference are arranged on the integrated alternating current input circuit board 1, and a front end capacitor 13 of the filter network 12 is directly bridged on a port of the alternating current input plug 11; namely, the structure design adopts an integrated AC input circuit board 1, an AC input plug 11 and a high-frequency filter network 12 are integrated on the AC input board 1 together, a front-end filter capacitor 13 of the high-frequency filter network 12 is directly connected across the port of the AC input plug 11, and AC signals from the high-frequency filter network 12 to a main circuit board 2 are transmitted by directly welding or other direct connection methods at the joint of the integrated AC input board and the main circuit board without using a flexible lead 3 as shown in FIG. 4-1. Such a configuration completely eliminates the need for the input flexible conductor 3 and the resulting electromagnetic interference coupling and provides the most effective filtering at the very front of the electromagnetic interference signal transmission, while also making the overall power supply more compact and uncluttered.

The above description is only for the preferred embodiment of the present invention, and is not intended to limit the present invention, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention should be included within the protection scope of the present invention.

Claims (7)

1. A high-efficiency charging power supply based on an E-type gallium nitride switch device is characterized by comprising a flyback switch circuit and a driving protection circuit, wherein the flyback switch circuit comprises a flyback transformer, the E-type gallium nitride switch device and an absorption circuit, and the driving protection circuit comprises a voltage stabilizing source and a diode;

the E-type gallium nitride switching device is in a conducting state when the gate control voltage is positive, and is cut off when the gate control voltage is zero;

and the diode in the drive protection circuit is connected with the voltage stabilizing source at the cathode and connected with the gate electrode of the E-type gallium nitride switching device at the anode, and is used for clamping the gate electrode voltage of the E-type gallium nitride switching device at a safe voltage level through the voltage stabilizing source.

2. The high efficiency charging power supply based on E-type GaN switching device of claim 1, wherein the driving protection circuit further comprises a zener diode connected in series with the diode to increase the clamping voltage of the gate of the E-type GaN switching device.

3. The efficient charging power supply based on the E-type gallium nitride switching device as claimed in claim 1, wherein the wires wound around the primary winding and the secondary winding of the flyback transformer are single-stranded flat wires, and the primary winding and the secondary winding are wound in a multi-layer overlapping manner.

4. The efficient charging power supply based on the E-type gallium nitride switching device as claimed in claim 1, wherein the primary winding and the secondary winding of the flyback transformer are wound side by using multi-strand wires and are wound in a multi-layer overlapping manner.

5. The high efficiency charging power supply based on type-E gallium nitride switching device according to claim 4, wherein the conducting wire is a flat conducting wire.

6. The high-efficiency charging power supply based on the E-type gallium nitride switching device is characterized in that the alternating current input end of the flyback transformer comprises an integrated alternating current input circuit board (1) and a power main circuit board (2), and an alternating current input plug (11) and a filter network (12) for suppressing electromagnetic interference are arranged on the integrated alternating current input circuit board (1);

and the filter network (12) on the integrated alternating current input circuit board (1) is electrically connected with the power main circuit (21) on the power main circuit board (2) through welding.

7. The efficient charging power supply based on the E-type gallium nitride switching device according to claim 6, wherein the filter network (12) further comprises a front-end capacitor (13), and the front-end capacitor (13) is directly connected across the port of the AC input plug (11).

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