阅读说明：本技术 一种mcu过流保护电路及其控制方法 (MCU overcurrent protection circuit and control method thereof ) 是由 刘兆斌 朱矿新 于 2019-09-24 设计创作，主要内容包括：本发明公开了一种MCU过流保护电路及其控制方法,用于保护MCU,包括电流采样模块、电压比较模块、MCU连接模块、定时触发模块和信息触发模块,通过电流采样模块采集输入MCU的电流信号I,并将电流信号转换为电压信号；电压信号输出至电压比较模块,和基准电压比较,大于基准电压则电流信号I过流,电压比较模块输出高电平；小于基准电压则电流信号I不过流,电压比较模块输出低电平。当电流信号I过流时,电流信号I通过保护连接电路连接MCU,定时器T启动计时,信息提示模块发出过流提示信号。本发明的MCU过流保护电路结构简单,控制方法可靠,电流检测准确,电路响应迅速,且成本较低,并能够有效地避免MCU因过流而烧毁,提高了电路的安全性和可靠性。(The invention discloses an MCU (microprogrammed control unit) overcurrent protection circuit and a control method thereof, which are used for protecting an MCU and comprise a current sampling module, a voltage comparison module, an MCU connection module, a timing trigger module and an information trigger module, wherein a current signal I input into the MCU is collected through the current sampling module, and is converted into a voltage signal; the voltage signal is output to a voltage comparison module, the voltage signal is compared with a reference voltage, if the voltage signal is greater than the reference voltage, the current signal I is over-current, and the voltage comparison module outputs a high level; and if the current signal I is less than the reference voltage, the current signal I does not overflow, and the voltage comparison module outputs a low level. When the current signal I is overcurrent, the current signal I is connected with the MCU through the protection connecting circuit, the timer T starts timing, and the information prompting module sends an overcurrent prompting signal. The MCU overcurrent protection circuit has the advantages of simple structure, reliable control method, accurate current detection, quick circuit response and lower cost, can effectively avoid the burning of the MCU due to overcurrent, and improves the safety and reliability of the circuit.)

1. An MCU overcurrent protection circuit, which is characterized in that the circuit is used for protecting MCU, comprising

A current sampling module: the MCU is used for acquiring a current signal I input into the MCU and converting the current signal I into a voltage signal;

a voltage comparison module: the input end of the voltage comparison module is connected with the first output end of the current sampling module, the voltage signal is compared with the reference voltage of the voltage comparison module, and a high level or a low level is output according to a comparison result;

MCU link module: the MCU connecting module comprises a normal connecting circuit and a protection connecting circuit, the control end of the MCU connecting module is connected with the output end of the voltage comparison module, the input end of the MCU connecting module is connected with the second output end of the current sampling module, the output end of the MCU connecting module is connected with the MCU, and the MCU connecting module selects the normal connecting circuit or the protection connecting circuit to be connected with the MCU according to the high level or the low level output by the voltage comparison module.

2. The MCU over-current protection circuit of claim 1, wherein the MCU over-current protection circuit further comprises

The timing trigger module: the output end of the timing trigger module is connected with the output end of the voltage comparison module, the output end of the timing trigger module is respectively connected with the live wire and the zero wire, and the timing trigger module controls the on-off of the zero wire and the live wire according to the high level or the low level output by the voltage comparison module;

the information prompt module: the control end of the information prompt module is connected with the output end of the voltage comparison module, and the information prompt module displays or closes overcurrent information according to the level signal output by the voltage comparison module.

3. The MCU overcurrent protection circuit as claimed in claim 1, wherein the current sampling module comprises a sampling resistor R1, a resistor R2, a resistor R3, a resistor R4 and an operational amplifier U1, one end of the sampling resistor R1 is connected to one end of the resistor R2, a common end of the sampling resistor R1 receives the current signal I, the other end of the resistor R1 is connected to one end of the resistor R3, a common end of the resistor R4 is connected to the input end of the MCU selection module, the other end of the resistor R2 is connected to one input end of the operational amplifier U1, the other end of the resistor R3 is connected to one end of the resistor R4, a common end of the resistor R3 is connected to the other input end of the operational amplifier U1, and a common end of the resistor R4 is connected to the output end of the operational amplifier U1 and the common end of.

4. The MCU overcurrent protection circuit of claim 1, wherein the voltage comparison module comprises a VCC power supply, a resistor R5, a resistor R6, and a comparator U2, one end of the resistor R5 is connected to the VCC power supply, the other end of the resistor R5 is connected to one end of the resistor R6, the common end of the resistor R5 is connected to the inverting input end of the comparator U2, the other end of the resistor R6 is grounded, the non-inverting input end of the comparator U2 is connected to the first output end of the current sampling module, and the output end of the comparator U2 is connected to the MCU connection module.

5. The MCU overcurrent protection circuit of claim 1, wherein the MCU connecting circuit comprises a first conduction switch, a second conduction switch, a PTC resistor, and an inverter U3, an input terminal of the inverter U3 is connected to a control terminal of the second conduction switch and a common terminal is connected to an output terminal of the voltage comparison module, an output terminal of the inverter U3 is connected to a control terminal of the first conduction switch, an input terminal of the first conduction switch is connected to an input terminal of the second conduction switch and a common terminal is connected to a second output terminal of the current sampling module, an output terminal of the first conduction switch is connected to one end of the PTC resistor and a common terminal is connected to an I/O port of the MCU, and the other end of the PTC resistor is connected to an output terminal of the second conduction switch.

6. The MCU overcurrent protection circuit of claim 5, wherein the first conduction switch and the second conduction switch are NPN transistors.

7. The MCU overcurrent protection circuit of claim 2, wherein the timing trigger module comprises a timer T and a normally closed switch K1, an input end of the timer T is connected with an output end of the voltage comparison module, an output end of the timer T is connected with a control end of the normally closed switch, and two ends of the normally closed switch are respectively connected with a voltage zero line and a thermal power.

8. The MCU overcurrent protection circuit of claim 2, wherein the information prompt module comprises a transistor Q3, a power supply Vcc, and an LED, wherein the base of the transistor Q3 is connected to the output of the voltage comparator, the collector of the transistor Q3 is connected to the power supply Vcc, the emitter of the transistor Q3 is connected to the anode of the LED, and the cathode of the LED is grounded.

9. A control method of an MCU overcurrent protection circuit, the control method being implemented by the MCU overcurrent protection circuit of any one of claims 1 to 8, comprising:

collecting a current signal I input into the MCU through a current sampling module, and converting the current signal into a voltage signal;

the voltage signal is output to a voltage comparison module and is compared with a reference voltage, if the voltage signal is greater than the reference voltage, the current signal I is over-current, and the voltage comparison module outputs a high level; if the current signal I is smaller than the reference voltage, the current signal I does not overflow, and the voltage comparison module outputs a low level;

when the current signal I is overcurrent, the current signal I is connected with the MCU through the protection connecting circuit, the timer T starts timing, and the information prompting module sends an overcurrent prompting signal.

10. The method as claimed in claim 9, wherein when the timer T is started for a time exceeding Ns, the normally closed switch K1 is opened to directly turn off the power supply.

Technical Field

The invention relates to the technical field of electronic circuits, in particular to an MCU (microprogrammed control unit) overcurrent protection circuit and a control method thereof.

Background

With the rapid development of the technology, the application of the MCU is more and more extensive. Due to the wide application of the MCU, the controller is more and more intelligent and simplified, the operation speed is greatly improved, and the control is more accurate and high-speed. However, when the MCU operates, the input/output current of the IO port cannot exceed its maximum value. When the switch power supply supplies power to the MCU, if the IO port is over-flowed due to the power supply short circuit, the MCU is burnt, the stronger the control function of the MCU is, the higher the price is, if the MCU is damaged, the economic loss can be caused; and because the pins of the MCU are more, the replacement is also more difficult. Therefore, adding an overcurrent protection circuit at the IO port plays an important role.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provides the MCU overcurrent protection circuit and the control method thereof, which can effectively avoid the burning of the MCU due to overcurrent and improve the safety and reliability of the circuit.

The purpose of the invention is realized by the following technical scheme in two aspects:

in a first aspect, the present invention provides an MCU overcurrent protection circuit for protecting an MCU, comprising

A current sampling module: the MCU is used for acquiring a current signal I input into the MCU and converting the current signal I into a voltage signal;

a voltage comparison module: the input end of the voltage comparison module is connected with the first output end of the current sampling module, the voltage signal is compared with the reference voltage of the voltage comparison module, and a high level or a low level is output according to a comparison result;

MCU link module: the MCU connecting module comprises a normal connecting circuit and a protection connecting circuit, the control end of the MCU connecting module is connected with the output end of the voltage comparison module, the input end of the MCU connecting module is connected with the second output end of the current sampling module, the output end of the MCU connecting module is connected with the MCU, and the MCU connecting module selects the normal connecting circuit or the protection connecting circuit to be connected with the MCU according to the high level or the low level output by the voltage comparison module.

Further, the MCU overcurrent protection circuit also comprises

The timing trigger module: the output end of the timing trigger module is connected with the output end of the voltage comparison module, the output end of the timing trigger module is respectively connected with the live wire and the zero wire, and the timing trigger module controls the on-off of the zero wire and the live wire according to the high level or the low level output by the voltage comparison module;

the information prompt module: the control end of the information prompt module is connected with the output end of the voltage comparison module, and the information prompt module displays or closes overcurrent information according to the level signal output by the voltage comparison module.

Further, the current sampling module includes a sampling resistor R1, a resistor R2, a resistor R3, a resistor R4 and an operational amplifier U1, one end of the sampling resistor R1 is connected to one end of the resistor R2 and a common end receives the current signal I, the other end of the resistor R1 is connected to one end of the resistor R3 and a common end is connected to the input end of the MCU selection module, the other end of the resistor R2 is connected to one input end of the operational amplifier U1, the other end of the resistor R3 is connected to one end of the resistor R4 and a common end is connected to the other input end of the operational amplifier U1, and the other end of the resistor R4 is connected to the output end of the operational amplifier U1 and a common end is connected to the voltage comparison module.

Further, the voltage comparison module includes VCC power, resistance R5, resistance R6, comparator U2, resistance R5's one end is connected the VCC power, resistance R5's the other end is connected resistance R6's one end and common terminal are connected comparator U2's inverting input end, resistance R6's other end ground connection, comparator U2's homophase input end is connected the first output of current sampling module, comparator U2's output is connected the MCU link module.

Further, MCU connecting circuit includes first switch on, second switch on, PTC resistance, phase inverter U3, phase inverter U3's input is connected the control end and the common terminal that the second switched on the switch are connected the output of voltage comparison module, phase inverter U3's output is connected the control end of first switch on, the input of first switch on is connected the input and the common terminal that the second switched on the switch are connected the second output of current sampling module, the output of first switch on is connected the I/O mouth of MCU is connected to the one end and the common terminal of PTC resistance, the other end of PTC resistance is connected the output that the second switched on the switch.

Further, the first conducting switch and the second conducting switch are both NPN triodes.

Further, the timing trigger module comprises a timer T and a normally closed switch K1, the input end of the timer T is connected with the output end of the voltage comparison module, the output end of the timer is connected with the control end of the normally closed switch, and two ends of the normally closed switch are respectively connected with a zero line and a thermal power of the voltage.

Further, the information prompt module comprises a triode Q3, a power supply Vcc and an LED, wherein the base electrode of the triode Q3 is connected with the output end of the voltage comparator, the collector electrode of the triode Q3 is connected with the power supply Vcc, the emitter electrode of the triode Q3 is connected with the anode of the LED, and the cathode of the LED is grounded.

In a second aspect, the present invention further provides a control method for an MCU overcurrent protection circuit, where the control method is implemented by the MCU overcurrent protection circuit of the first aspect, and includes:

collecting a current signal I input into the MCU through a current sampling module, and converting the current signal into a voltage signal;

the voltage signal is output to a voltage comparison module and is compared with a reference voltage, if the voltage signal is greater than the reference voltage, the current signal I is over-current, and the voltage comparison module outputs a high level; and if the current signal I is less than the reference voltage, the current signal I does not overflow, and the voltage comparison module outputs a low level.

When the current signal I is overcurrent, the current signal I is connected with the MCU through the protection connecting circuit, the timer T starts timing, and the information prompting module sends an overcurrent prompting signal.

Further, when the starting time of the timer T exceeds Ns, the normally closed switch K1 is opened, and the power supply is directly turned off.

The invention has the beneficial effects that: the invention discloses an MCU (microprogrammed control unit) overcurrent protection circuit and a control method thereof. When the input and output current of the IO port is larger than the maximum current value which can be borne by the IO port, the MCU can be effectively prevented from being burnt due to overcurrent through reliable control logic and circuits, and therefore the safety and the reliability of the circuit are improved.

Drawings

The invention is further illustrated by means of the attached drawings, but the embodiments in the drawings do not constitute any limitation to the invention, and for a person skilled in the art, other drawings can be derived on the basis of the following drawings without inventive effort.

Fig. 1 is a circuit configuration diagram of an MCU overcurrent protection circuit according to an embodiment of the present invention.

Fig. 2 is a schematic flow chart of a control method of the MCU overcurrent protection circuit according to an embodiment of the present invention.

Wherein the reference numbers are as follows: 10. the device comprises a current sampling module, 20 a voltage comparison module, 30 an MCU connection module, 40 a timing trigger module and 50 an information prompt module.

Detailed Description

In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In a digital circuit, the high and low of a voltage are represented by logic levels, which include both high and low levels. The digital circuits formed by different components have different logic levels corresponding to voltages. The logic level is defined by a threshold level, e.g., in a TTL gate circuit, a voltage greater than 3.5 volts (threshold high level) is defined as a logic high level, represented by the number 1; a voltage less than 0.3 volts (threshold low level) is defined as a logic low level, represented by the number 0.

As shown in fig. 1, the MCU overcurrent protection circuit of this embodiment, for protecting MCU, includes

The current sampling module 10: the MCU is used for acquiring a current signal I input into the MCU, converting the current signal I into a voltage signal and amplifying the voltage signal;

the voltage comparison module 20: the input end of the voltage comparison module 20 is connected to the first output end of the current sampling module 10, compares the voltage signal with the reference voltage of the voltage comparison module 20, and outputs a high level or a low level according to the comparison result;

the MCU connection module 30: the MCU connection module 30 comprises a normal connection circuit and a protection connection circuit, the control end of the MCU connection module 30 is connected with the output end of the voltage comparison module 20, the input end of the MCU connection module 30 is connected with the second output end of the current sampling module 10, the output end of the MCU connection module 30 is connected with the MCU, and the MCU connection module 30 selects the normal connection circuit or the protection connection circuit to be connected with the MCU according to the high level or the low level output by the voltage comparison module 20.

The timing trigger module 40: the output end of the timing trigger module 40 is connected with the output end of the voltage comparison module 20, the output end of the timing trigger module 40 is respectively connected with the live wire and the zero wire, and the timing trigger module 40 controls the on-off of the zero wire and the live wire according to the high level or the low level output by the voltage comparison module 20;

the information prompt module 50: the control end of the information prompt module 50 is connected to the output end of the voltage comparison module 20, and the information prompt module 50 displays or closes the overcurrent information according to the level signal output by the voltage comparison module 20.

The current sampling module 10 includes a sampling resistor R1, a resistor R2, a resistor R3, a resistor R4, and an operational amplifier U1, one end of the sampling resistor R1 is connected to one end of the resistor R2, and a common terminal receives the current signal I, the other end of the resistor R1 is connected to one end of the resistor R3, and a common terminal is connected to an input terminal of the MCU selection module, the other end of the resistor R2 is connected to an input terminal of the operational amplifier U1, the other end of the resistor R3 is connected to one end of the resistor R4, and a common terminal is connected to another input terminal of the operational amplifier U1, the other end of the resistor R4 is connected to an output terminal of the operational amplifier U1, and a common.

The resistor R1 is a sampling resistor, the voltage drop at two ends of the sampling resistor R1 is V, the operational amplifier U1 is used for obtaining the voltage drop V of the sampling resistor R1 and outputting the V after amplifying, and the amplification factor is as shown in formula (1):

B = R4/R3 （1）。

in this embodiment, the rated current flowing into the I/O port of the MCU is I_MAXThen the voltage drop V rating of the resistor R1 is sampled_MAXAs shown in formula (2):

V_MAX= I_MAX*R₁（2）。

the voltage output by the operational amplifier U1 is V_ARated output voltage of V_AMAXThen:

V_AMAX= V_MAX*B （3）。

the voltage comparison module 20 includes a VCC power supply, a resistor R5, a resistor R6, and a comparator U2, one end of the resistor R5 is connected to the VCC power supply, the other end of the resistor R5 is connected to one end of the resistor R6, and the common end is connected to the inverting input end of the comparator U2, the other end of the resistor R6 is grounded, the non-inverting input end of the comparator U2 is connected to the output end of the operational amplifier U1, and the output end of the comparator U2 is connected to the MCU connection module 30.

The non-inverting input terminal of the comparator U1 is used for obtaining the voltage V output by the operational amplifier U1_AThe inverting input end of the comparator U1 is connected with a reference voltage V_BThe reference voltage is determined by dividing voltage by a resistor R5 and a resistor R6, and is expressed by formula (4):

V_B= R6/（R5+R6）*VCC （4）。

when the voltage V output by the operational amplifier U1_AGreater than a reference voltage V_BWhen the voltage is high, the comparator outputs high level;

when the voltage V output by the operational amplifier U1_ALess than reference voltage V_BWhen the voltage is high, the comparator outputs a low level.

By setting the values of the resistors R5 and R6, the following are set:

V_B= V_AMAX（5）。

when the formula (5) is satisfied, when the current signal I input to the I/O port of the MCU exceeds the rated current I_MAXWhen the current signal I is considered to be overcurrent, the voltage drop V between the two ends of the sampling resistor R1 is larger than V as shown in the formulas (1) and (2)_MAXFrom the formula (3)The voltage output by the operational amplifier U1 is V_AWill be greater than V_AMAXAs can be seen from the formula (5), V is a value obtained in the case of overcurrent_AWill be greater than V_BThereby causing the comparator U2 to output a high level; similarly, it can be known that when the current signal I is not greater than the rated current I_MAXWhen the current signal I is not overcurrent, the comparator U2 outputs a low level.

Wherein, MCU connecting circuit includes first switch on, the second switches on the switch, PTC resistance, phase inverter U3, the output of comparator U2 is connected to the control end and the common port that the second switched on the switch is connected to phase inverter U3's input, the control end of first switch on is connected to phase inverter U3's output, the input that the second switched on the switch is connected to the first input that switches on the switch and the output of common port connecting resistance R1, the I/O mouth of MCU is connected to the one end and the common port that first switch on switch's output connection PTC resistance, the second switch on switch's output is connected to the other end of PTC resistance.

The first conducting switch is an NPN transistor Q1, and the second conducting switch is an NPN transistor Q2.

The normal connecting circuit is composed of the triode Q1 and the direction indicator U3, the protective connecting circuit is composed of the triode Q2 and the PTC resistor, when the current signal I is overcurrent, the comparator U2 outputs a high level, the high level is converted into a low level after passing through the inverter U3, the triode Q1 is turned off, the triode Q2 is conducted, the current signal I flows through the sampling resistor R1 and then is connected to the MCU through the protective connecting circuit, the PTC is a positive temperature coefficient in the embodiment, the resistance value of the PTC is increased along with the rise of the temperature, and the effect of restraining the current is achieved.

When the current signal I does not flow through the sampling resistor R1, the comparator U2 outputs a low level, and after passing through the inverter U3, the low level is converted into a high level, so that the transistor Q1 is turned on, and the transistor Q2 is turned off, and the current signal I flows through the sampling resistor R1 and then is connected to the MCU through a normal connection circuit.

The timing trigger module 40 comprises a timer T and a normally closed switch K1, wherein the input end of the timer T is connected with the output end of the voltage comparison module 20, the output end of the timer is connected with the control end of the normally closed switch, and the two ends of the normally closed switch are respectively connected with a voltage zero line and a thermal power.

The timer T starts after receiving the high level and outputs a signal capable of turning off the normally-closed switch K1 after a certain period of time, the normally-closed switch K1 is a switching device capable of changing state by a control end, such as a triode, a mos tube, a relay, etc., for example:

the normally closed switch K1 is a relay, one end of a coil of the relay is grounded, the other end of the coil of the relay is connected with the output end of the timer T, the switch of the relay is in a normally closed state, and the two ends of the switch are respectively connected with a zero line and a live line of power supply voltage;

after the current signal I is over-current, the timer T receives a high level and starts timing, and when the timing time reaches the preset Ns, the timer T outputs a high level to enable the coil of the relay to be conducted, so that the switching state of the relay is changed, and the circuit and the power supply voltage are thoroughly disconnected.

By the timing function of the timer T, all power supplies are completely shut down only after the overcurrent time reaches Ns, and the problem that the MCU is shut down due to interference signals is avoided.

The information prompt module 50 comprises a triode Q3, a power supply Vcc and an LED, wherein the base electrode of the triode Q3 is connected with the output end of the voltage comparator, the collector electrode of the triode Q3 is connected with the power supply Vcc, the emitter electrode of the triode Q3 is connected with the anode of the LED, and the cathode of the LED is grounded.

The transistor Q3 is an NPN transistor, and other conducting switches capable of achieving the same function are also within the scope of the present invention, where the LED is an LED of any color, and may also be other light emitting elements or other devices capable of playing a role of prompting, such as a buzzer, a speaker, and the like.

After the current signal I is overcurrent, the triode Q3 is conducted, so that the LED emits light to remind maintenance personnel and users, and the maintenance personnel can conveniently find problems.

The working principle of the embodiment is as follows: when the current signal I flowing into the I/O port of the MCU does not overflow, the sampled comparator U2 outputs a low level, the MCU connection module 30 is connected to the MCU through a normal connection circuit, the timing trigger module 40 is not started, the information prompt module 50 is not started, and the MCU operates normally.

When a current signal I flowing into an I/O port of the MCU is overcurrent, the sampled current signal I is output by the comparator U2 to be in a high level, the MCU connecting module 30 is connected with the MCU through the protection connecting circuit, the timer triggering module starts the timer, the information prompting module 50 sends out overcurrent prompt, and the MCU continues to operate in an overcurrent protection state.

When the overcurrent time of the current signal I flowing into the I/O port of the MCU reaches Ns and the overcurrent signal is not released, the timing trigger module 40 closes the zero line and the live line of the power supply voltage through the normally closed switch K1, completely closes all power supplies, and the MCU stops running.

The embodiment also provides a control method of the MCU overcurrent protection circuit, where the control method is implemented by the MCU overcurrent protection circuit of the embodiment and includes:

a current signal I input into the MCU is collected through a current sampling module 10, and the current signal is converted into a voltage signal and amplified;

the voltage signal is output to the voltage comparison module 20, and compared with the reference voltage, if the voltage signal is greater than the reference voltage, the current signal I is over-current, and the voltage comparison module 20 outputs a high level; if the current signal I is less than the reference voltage, the current signal I does not overflow, and the voltage comparison module 20 outputs a low level.

When the current signal I is overcurrent, the current signal I is connected to the MCU through the protection connection circuit, the timer T starts timing, and the information prompt module 50 sends an overcurrent prompt signal.

When the starting time of the timer T exceeds Ns, the normally closed switch K1 is opened, and the power supply is directly closed.

In the embodiment, the current detection circuit is added at the I/O port of the MCU to realize the real-time detection of the current of the IO port; if not, the operation is normal; if the power supply circuit causes the IO port to be over-current, the over-current protection circuit is started through a control logic method, the MCU is prevented from being burnt out due to over-current, and an over-current prompt is sent out; if the overcurrent exceeds a certain time, cutting off the zero-live wire power supply and stopping running; instantaneous overcurrent can be restrained through overcurrent timing, and the circuit automatically returns to normal work after the current returns to normal.

It can be seen from this embodiment that, the MCU overcurrent protection circuit and the control method thereof of this embodiment have the advantages of simple structure, reliable control method, accurate current detection, fast circuit response, and low cost. When the input and output current of the IO port is larger than the maximum current value which can be borne by the IO port, the MCU can be effectively prevented from being burnt due to overcurrent through reliable control logic and circuits, and therefore the safety and the reliability of the circuit are improved.

Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the protection scope of the present invention, although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.