TWI686028B - Battery protection architecture - Google Patents

Abstract

The present invention is a battery protection architecture, including a power switch element, an overcurrent protection setting resistor, a protection controller, a first diode, a second diode, a switch, and a current sensing resistor, to provide a battery protection function. Mainly use constant current to flow through the overcurrent protection setting resistor to generate the overcurrent voltage threshold, which is used as a reference level for overcurrent protection. Users can use the optimal overcurrent protection setting resistor to flexibly adjust the overcurrent voltage threshold Limit. Furthermore, the protection controller controls the switch to switch the first diode and the second diode to close the charge and discharge circuit to avoid damage to the power switching element when an abnormal state of overcurrent occurs during charging or discharging. To achieve the purpose of overcurrent protection.

Description

Battery protection architecture

The present invention is a battery protection architecture, especially for a rechargeable battery protection architecture, including a protection controller, a power switching element (such as a MOSFET), a first diode, a second diode, a switch, and overcurrent protection Setting resistance is used to realize the protection of overcharge and overdischarge when the single chip completes the charge and discharge of the rechargeable battery. The protection controller mainly controls the switching of the first diode and the second diode in the integrated power switching element to prevent overcharging, overdischarging, overvoltage and overtemperature during battery charging or discharging. In abnormal state, close the charge and discharge circuit to avoid damage or injury of the battery and increase the protection of the power switching element to achieve the purpose of protecting the battery. Furthermore, the constant current flows through the overcurrent protection setting resistor to generate the overcurrent voltage threshold, which is used as a reference level for overcurrent protection. The user can use the optimal overcurrent protection setting resistor to flexibly adjust the overcurrent Threshold.

With the continuous advancement of technology in the electronics industry, various portable electronic products have become more and more popular, including mobile phones, tablet computers, notebook computers, portable audio and video players, wireless headphones, and the configured portable power supply generally includes traditional Dry batteries and alkaline batteries, but this type of disposable batteries can only be used once. When the power output drops to the lower limit, they must be discarded, causing a lot of garbage that is difficult to handle, so it is very environmentally friendly and wastes resources. Therefore, most portable electronic products are replaced by rechargeable batteries that can bear multiple charge and discharge cycles, such as lithium batteries.

It is well known that the materials used in rechargeable batteries are quite unstable, and when charging When the battery is overcharged or overdischarged, it will easily cause an explosion, which is very dangerous and poses a serious challenge to the safety of use.

In the conventional technology, in order to avoid the problem of overcharge or overdischarge, as shown in the first figure, the controller M, the first unipolar body D1, the second diode D2, the first transistor MOS1 and the first transistor are used. The two transistors MOS2 form a protection structure to protect the rechargeable battery B. The specific method is that during normal charging or discharging, the controller M turns on the first transistor MOS1 and the second transistor MOS2, and turns off the first diode D1 and the second diode D2, and a charging overcurrent occurs At this time, the first transistor MOS1 is turned off, and the first diode D1 is turned on. If it is a discharge overcurrent, the second transistor MOS2 is turned off, and the second diode D2 is turned on. Furthermore, the threshold of overcurrent protection is set to a fixed voltage level, which is regarded as a protection point for overcurrent, such as 150mV, generally through the on-resistance of the first transistor MOS1 and the second transistor MOS2. That is RDS (ON), to select and determine the magnitude of overcurrent.

However, the disadvantage of the above-mentioned conventional technology is that the first transistor MOS1 and the second transistor MOS2 are connected in series. Therefore, under normal operating conditions, the charging current or the discharge current will flow in series through the first transistor MOS1 and the second transistor The crystal MOS2 consumes part of the power and causes good costs. At the same time, it reduces the voltage across the positive terminal BTT+ and the negative terminal BTT+ in the system, affecting the charging and discharging efficiency of the rechargeable battery B.

In addition, the threshold value of overcurrent protection in the conventional technology is a fixed value on the circuit hardware, and the user cannot change it. When it is necessary to meet the needs of different overcurrent levels, it is obvious that only the corresponding controller M can be replaced. , Thus greatly reducing the convenience of application.

Therefore, there is a great need for an innovative battery protection architecture, which uses a constant current of a fixed power supply to flow through an overcurrent protection setting resistor, and sets the generated voltage as an overcurrent voltage threshold, It is used as a reference level for overcurrent protection, so users can use the overcurrent protection setting resistor with the best resistance value to adjust the overcurrent voltage threshold according to actual needs. Furthermore, use the switch to switch The first diode and the second diode are used to close the charge and discharge circuit to avoid damage to the power switching element and achieve the purpose of overcurrent protection when the abnormal state of overcurrent occurs during charging or discharging to solve the problem of conventional technology .

The main object of the present invention is to provide a battery protection architecture, including a power switching element, an overcurrent protection setting resistor, a protection controller, a first diode, a second diode, a switch, and a current sensing resistor to provide Battery protection function to avoid over-voltage, over-current, and over-temperature. The power switching element can be a metal-oxide half field effect transistor (MOSFET) with drain, gate, and source, and the protection controller can be micro-control Device (MCU). In addition, the drain-to-source crossover voltage is regarded as the charge-on voltage, and the source-to-drain crossover voltage is regarded as the discharge-on voltage.

Specifically, the protection controller has a power terminal, a ground terminal, an overcurrent voltage setting terminal, a control terminal, a switching terminal, and a current sensing terminal, where the control terminal is a gate connected to the power switching element, and the power terminal and the ground terminal are Connected to the positive and negative poles of the rechargeable battery respectively, and the drain of the power switching element is connected to the negative pole of the rechargeable battery, the overcurrent voltage setting end of the protection controller is connected to one end of the overcurrent protection setting resistance, and the other of the overcurrent protection setting resistance One end is connected to the negative electrode of the rechargeable battery.

In addition, the anode of the first diode is connected to the drain of the power switching element, and the cathode of the second diode is connected to the drain of the power switching element. The switch has an input terminal, a first output terminal and a second output terminal, wherein the input terminal is connected to the switching terminal of the protection controller, and the first output terminal It is connected to the negative electrode of the first diode, and the second output terminal is connected to the positive electrode of the second diode. Further, the current sensing terminal is connected to one end of the current sensing resistor, and the other end of the current sensing resistor is connected to the source of the power switching element, and the current sensing terminal generates the current sensing voltage.

The positive electrode of the rechargeable battery is connected to the positive terminal, and the source of the power switching element is further connected to the negative terminal, and the positive terminal and the negative terminal are further connected to external devices, wherein the rechargeable battery can be a lithium-based rechargeable battery, and the external device can be a charging integrated circuit (Charger IC), boost (Boost) IC or buck (Buck) IC.

In particular, the protection controller contains a constant current source and a processing core. The constant current source generates a constant current and outputs it to the overcurrent voltage setting terminal. At this time, the voltage at the overcurrent voltage setting terminal is regarded as the overcurrent voltage threshold. The processing core receives and compares the over-current voltage threshold, the charge-on voltage and the discharge-on voltage to generate and output a control signal to the control terminal, and at the same time generate and output a switching signal to the switching terminal. When the charge-on voltage is positive, the processing core determines that the rechargeable battery is charging, and when the discharge-on voltage is positive, the processing core determines that the rechargeable battery is discharging.

When the rechargeable battery is charged and the charge-on voltage is greater than or equal to the overcurrent voltage threshold, it indicates that the rechargeable battery is overcharged (overcharged). Therefore, the control signal turns off the power switch element, and the switch is based on the switch signal to The input terminal is connected to the first output terminal, and then the first diode is turned on, and the second diode is turned off.

When the rechargeable battery is discharged and the discharge conduction voltage is greater than or equal to the overcurrent voltage threshold, indicating that overcharge (overdischarge) occurs, the power switch element is turned off by the control signal, and the switch is connected to the input terminal according to the switch signal to the first The two output terminals turn off the first diode and turn on the second diode.

When the rechargeable battery is charged and the charge-on voltage is less than the overcurrent voltage threshold, or when the discharge battery is discharged and the discharge-on voltage is less than the overcurrent voltage threshold, the power switching element is turned on by the control signal, and the switch is based on The switching signal turns off the first diode and the second diode.

Therefore, the present invention can specifically realize the protection function during overcharge and overdischarge.

In addition, the processing core can also monitor whether the overall temperature exceeds the threshold to determine whether excessive high temperature (over temperature) occurs, such as whether the power switching element or the processing core itself is over temperature, and then realize the over temperature protection function.

Obviously, the present invention uses the constant current of the fixed power supply to flow through the overcurrent protection setting resistor, and sets the generated voltage as the overcurrent voltage threshold, so as to provide a reference level for overcurrent protection, so the user can according to actual needs Use the over-current protection setting resistor with the best resistance value to achieve the purpose of elastically adjusting the over-current voltage threshold. Furthermore, use the switch to switch the first diode and the second diode for charging or When an abnormal state of overcurrent occurs during discharge, close the charge and discharge circuit to avoid damage to the power switching element and achieve the purpose of overcurrent protection.

10‧‧‧Protection controller

12‧‧‧ Constant current source

14‧‧‧ processing core

20‧‧‧Switch

B‧‧‧rechargeable battery

BTT+‧‧‧Positive extreme

BTT-‧‧‧Negative terminal

D1‧‧‧ First Diode

D2‧‧‧ Second Diode

I‧‧‧Constant current

IN‧‧‧input

M‧‧‧Controller

MOS1‧‧‧First transistor

MOS2‧‧‧second transistor

OUT1‧‧‧ First output

OUT2‧‧‧second output

Q‧‧‧Power switch element

ROV‧‧‧Overcurrent protection setting resistance

RCS‧‧‧Current sensing resistor

VCT‧‧‧Control signal

VSW‧‧‧switch signal

X‧‧‧First node

Y‧‧‧The second node

CT‧‧‧Control

CS‧‧‧Current sensing terminal

GND‧‧‧Ground terminal

OV‧‧‧Over voltage setting terminal

SW‧‧‧Switch

VCC‧‧‧Power terminal

The first figure shows a schematic diagram of a conventional technology battery protection architecture.

The second figure shows a schematic diagram of a battery protection architecture according to an embodiment of the invention.

The embodiments of the present invention will be described in more detail below with reference to icons and component symbols, so that those skilled in the art can implement them after studying this specification.

Please refer to the second figure, a schematic diagram of a battery protection architecture according to an embodiment of the present invention. As shown in the second figure, the battery protection architecture of the embodiment of the present invention includes a power switching element Q and overcurrent protection Setting resistance ROV, protection controller 10, first diode D1, second diode D2, change-over switch 20 and current sensing resistor RCS to provide battery protection function to avoid over-voltage, over-current and over-temperature . The power switching element Q, the protection controller 10, the first diode D1, the second diode D2, the change-over switch 20 and the current sensing resistor RCS may be discrete components, or may be better integrated into a single product Circuit (IC).

The above-mentioned power switching element Q may be a metal oxide semiconductor field effect transistor (MOSFET), and has a drain, a gate, and a source, and the protection controller 10 may be a microcontroller (MCU).

Furthermore, the drain-to-source crossover voltage of the power switching element Q is regarded as the charging conduction voltage, and the source-to-drain crossover voltage is regarded as the discharge conduction voltage.

Specifically, the protection controller 10 has a power terminal VCC, a ground terminal GND, an overvoltage setting terminal OV, a control terminal CT, a switching terminal SW, and a current sensing terminal CS, wherein the power terminal VCC and the ground terminal GND are respectively connected to the rechargeable battery B Positive and negative, and the protection controller 10 senses the terminal voltage of the rechargeable battery B through the power terminal VCC and the ground terminal GND, and outputs a control signal through the control terminal CT to turn on or off the power switching element Q, and at the same time, The switching terminal SW outputs a switching signal for turning on or off the first diode D1 and the second diode D2.

The positive and negative terminals of the rechargeable battery B are connected to the positive terminal BTT+ and the negative terminal BTT-, respectively, and the positive terminal BTT+ and the negative terminal BTT- are further connected to external devices (not shown in the figure), such as a charging IC (Charger IC), Boost (Boost) IC, buck (Buck) IC. Furthermore, the above-mentioned rechargeable battery B may be a lithium-based rechargeable battery.

In addition, the overcurrent voltage setting terminal OV of the protection controller 10 is connected to one end of the overcurrent protection setting resistor ROV, and the other end of the overcurrent protection setting resistor ROV is connected to the negative electrode of the rechargeable battery B. The anode of the first diode D1 is connected to the drain of the power switching element Q, and the first The cathode of the diode D2 is the drain connected to the power switching element Q.

The switch 20 has an input terminal IN, a first output terminal OUT1 and a second output terminal OUT2, wherein the input terminal IN is connected to the switching terminal SW of the protection controller 10, and the first output terminal OUT1 is connected to the negative electrode of the first diode D1 , And the second output terminal OUT2 is connected to the positive electrode of the second diode D2. Further, the current sensing terminal CS is connected to one end of the current sensing resistor RCS, and the other end of the current sensing resistor RCS is connected to the source of the power switching element Q, and the current sensing terminal CS generates a current sensing voltage.

More specifically, the protection controller 10 includes a constant current source 12 and a processing core 14, wherein the constant current source 12 generates and outputs a constant current I to the overcurrent voltage setting terminal OV, and then flows through the overcurrent protection setting resistance ROV, and The voltage at the overcurrent voltage setting terminal OV is regarded as the overcurrent voltage threshold, and the processing core 14 receives and compares the overcurrent voltage threshold, the charge-on voltage and the discharge-on voltage to generate and output the control signal VCT to the control The terminal CT simultaneously generates and outputs a switching signal VSW to the switching terminal SW.

When the charge-on voltage is positive, it indicates that there is a current flowing from node X to node Y, so the processing core 14 determines that the rechargeable battery B is charging, and when the discharge-on voltage is positive, it indicates that a current flows from node Y to the node X, so the processing core 14 determines that the rechargeable battery is discharging.

If the rechargeable battery B is being charged and the charge-on voltage is greater than or equal to the overcurrent voltage threshold, it means that the rechargeable battery B has abnormally overcharged (or simply referred to as overcharge), and the charging current is too large. Therefore, the control signal VCT turns off the power switching element Q, and at the same time, the switch 20 connects the input terminal IN to the first output terminal OUT1 according to the switching signal VSW, thereby turning on the first diode D1 and turning off the second diode D2. Its effect is to directly charge the excessive charging current It flows through the first diode D1 without flowing through the power switching element Q, thereby protecting the power switching element Q from damage.

If the rechargeable battery B is discharging and the discharge conduction voltage is greater than or equal to the overcurrent voltage threshold, it means that an abnormal state of overcharging (or simply overdischarge) occurs and the discharge current is too large. At this time, the control signal VCT turns off the power switch The element Q and the switch 20 simultaneously connect the input terminal IN to the second output terminal OUT2 according to the switching signal VSW, thereby turning off the first diode D1 and turning on the second diode D2. At this time, the effect achieved is that an excessive discharge current flows directly through the second diode D2 without flowing through the power switching element Q, thereby protecting the power switching element Q from damage.

If the rechargeable battery B is charged and the charge-on voltage is less than the overcurrent voltage threshold, which is the normal state of charge, or if the discharge battery B is discharged and the discharge-on voltage is less than the overcurrent voltage threshold, which is normal In the discharge state, the control signal VCT turns on the power switching element Q, and the switch 20 turns off the first diode D1 and the second diode D2 at the same time according to the switch signal VSW.

Preferably, when the processing core 14 is turned on, the generated control signal VCT is used to turn on the power switching element Q, and at the same time, the generated switching signal VSW turns off the first diode D1 and the second diode at the same time D2, that is, in the initial state, the power switching element Q is turned on, and the first diode D1 and the second diode D2 are turned off.

In addition, the processing core 14 can further provide an over-temperature (over-temperature) protection function, mainly to detect and monitor the temperature of the power switching element Q or the temperature of the entire protection controller 10, and when the temperature exceeds the threshold temperature, It is considered that an abnormal state of over temperature has occurred. At this time, the processing core 14 drives the control signal to turn off the power switching element, and drives the switching signal by the switching switch Turn off the first diode and the first diode.

In summary, the present invention is characterized by using a constant current of a fixed power source to flow through an overcurrent protection setting resistor, and setting the generated voltage as an overcurrent voltage threshold. The reference level for overcurrent protection can be based on actual conditions. It is necessary to use the overcurrent protection setting resistor with the best resistance value to achieve the purpose of elastically adjusting the overcurrent voltage threshold.

Another feature of the present invention is that the first diode and the second diode are switched by using a switch to form a bypass path to guide the abnormal overcurrent when an abnormal state of overcurrent occurs during charging or discharging , To avoid damage to the power switching element, to achieve the purpose of overcurrent protection. In particular, the present invention can use only a single power switching element, greatly simplifying system configuration and circuit layout, and improving the reliability and stability of operation.

The above are only for explaining the preferred embodiments of the present invention, and are not intended to limit the present invention in any form, so that any modifications or changes made to the present invention under the same spirit of the invention , Should still be included in the scope of protection of the present invention.

10‧‧‧Protection controller

12‧‧‧ Constant current source

14‧‧‧ processing core

20‧‧‧Switch

B‧‧‧rechargeable battery

BTT+‧‧‧Positive extreme

BTT-‧‧‧Negative terminal

D1‧‧‧ First Diode

D2‧‧‧ Second Diode

I‧‧‧Constant current

IN‧‧‧input

OUT1‧‧‧ First output

OUT2‧‧‧second output

Q‧‧‧Power switch element

ROV‧‧‧Overcurrent protection setting resistance

RCS‧‧‧Current sensing resistor

VCT‧‧‧Control signal

VSW‧‧‧switch signal

X‧‧‧First node

Y‧‧‧The second node

Claims (6)

A battery protection architecture includes: a power switching element having a drain, a gate, and a source, and the voltage across the drain to the source is a charge-on voltage, and the source to the drain The voltage across is a discharge conduction voltage; a protection controller has a power supply terminal, a ground terminal, an overcurrent voltage setting terminal, a control terminal, a switching terminal and a current sensing terminal, the control terminal is connected to The gate electrode of the power switch element, and the power terminal and the ground terminal are respectively connected to a positive electrode and a negative electrode of a rechargeable battery, the drain electrode of the power switch element is connected to the negative electrode of the rechargeable battery; an overcurrent protection setting resistance , The overcurrent voltage setting end of the protection controller is connected to one end of the overcurrent protection setting resistor, and the other end of the overcurrent protection setting resistor is connected to the negative electrode of the rechargeable battery; a first diode, having A positive pole and a negative pole, the positive pole is connected to the drain of the power switching element; a second diode has a positive pole and a negative pole, the negative pole is connected to the drain of the power switching element; a switch, has a An input terminal, a first output terminal and a second output terminal, the input terminal is connected to the switching terminal of the protection controller, the first output terminal is connected to the negative electrode of the first diode, and the second output terminal is connected To the anode of the second diode; and a current sensing resistor, the current sensing terminal is connected to one end of the current sensing resistor, and the other end of the current sensing resistor is connected to the power switching element Source, the current sensing terminal generates a current sensing voltage, wherein the positive electrode of the rechargeable battery is connected to a positive terminal, and the source electrode of the power switching element is further connected to a negative terminal, and the positive terminal and the negative terminal are further connected An external device, the protection controller includes a certain current source and a processing core, the constant current source generates a certain current and outputs to The over-current voltage setting terminal, and the voltage at the over-current voltage setting terminal is an over-current voltage threshold, the processing core receives and compares the over-current voltage threshold, the charge-on voltage and the discharge-on voltage to generate And output a control signal to the control terminal, and simultaneously generate and output a switching signal to the switching terminal. When the charging conduction voltage is a positive value, the processing core judges that the rechargeable battery is being charged, and the discharging conduction voltage is a When the value is positive, the processing core determines that the rechargeable battery is discharging. When the rechargeable battery is being charged and the charge-on voltage is greater than or equal to the overcurrent voltage threshold, it indicates that overcharge (overcharge) has occurred. The signal turns off the power switch element, and at the same time, the changeover switch connects the input terminal to the first output terminal according to the switching signal, and then turns on the first diode, and turns off the second diode when the rechargeable battery is in operation When the discharge and the discharge conduction voltage is greater than or equal to the overcurrent voltage threshold, it indicates that excessive discharge (overdischarge) occurs, the control signal turns off the power switch element, and the switch is connected to the input terminal according to the switch signal The second output terminal further turns off the first diode and turns on the second diode, when the rechargeable battery is being charged and the charging conduction voltage is less than the overcurrent voltage threshold, or when the discharge battery When discharging and the discharge conduction voltage is less than the overcurrent voltage threshold, the power switching element is turned on by the control signal, and the first diode and the second diode are simultaneously turned off by the switch according to the switch signal body. According to the battery protection architecture described in item 1 of the patent application scope, wherein the rechargeable battery is a lithium rechargeable battery, and the external device is a charge IC, a boost IC or a drop IC Press (Buck) IC. According to the battery protection architecture described in item 1 of the patent application scope, the protection controller is implemented by a microcontroller (MCU). According to the battery protection architecture described in item 1 of the patent application scope, wherein the power switching element is a metal oxide half field effect transistor (MOSFET). According to the battery protection architecture described in item 1 of the patent application scope, the processing core further When excessive high temperature (overtemperature) occurs in the power switching element or the processing core, the control signal is driven to turn off the power switching element, and the switching signal is driven to turn off the first diode and the first by the switching switch Diode. According to the battery protection architecture described in item 1 of the patent application scope, wherein the power switching element, the protection controller, the first diode, the two diode, the switch, and the current sensing resistor are integrated into one Single integrated circuit (IC).

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