TW200822484A - Method for battery pack protection - Google Patents

Abstract

Battery protection circuitry and method are disclosed. A battery is protected from a large current overdrawn condition by setting a discharge switch into a controllable conduction state. After the discharge switch is in the controllable conduction state, a tickle discharge current is gradually generated under control of a control signal. The trickle discharge current can be used to determine whether the large current overdrawn condition still exists. When the large current overdrawn condition is removed, the discharge switch is turned back on.

Description

200822484 IX. INSTRUCTIONS OF THE INVENTION: TECHNICAL FIELD The present invention relates to a battery charging/discharging circuit and a battery pack protection method, and more particularly to a method capable of performing trickle precharge and/or turbulent discharge. Battery charge/discharge circuit and protection method. The utility of the present invention can be found in a discharge/protection system for use in portable electronic devices, such as laptops, personal digital assistants (Pers〇nal).

Digital Assistant, PDA), cell phone, and/or any type of electronic moxibustion with rechargeable battery. ^ 10 [Prior Art] Rechargeable batteries, especially miscellaneous batteries, must be precharged (recharged) to avoid damage to the battery. When the battery is depleted and the battery voltage is depleted and its battery voltage becomes critical, the battery cannot be directly charged with a charging current of 15 A. Conversely, the battery needs to be charged using a pre-charge mode. Xiangsi Lai, the gamma charging battery is charged until the battery voltage is charged to be greater than the threshold voltage Vuv, and then it can be charged in the normal mode 'that is, charging a large charging current for charging. For a lithium-ion battery, the threshold voltage Vuv of a cell is close to 2.4V~3. 〇v, depending on the type of battery and the privacy of the device. The precharge current is about 1 〇 wall ~1〇〇11^. However, the normal charging current can be several hundred milliamperes to several amperes, and Figure 1A shows the charging profile of the lithium ion rechargeable battery. When the battery voltage is still at Vuv, the battery enters a constant current (〇〇 时 时 町 町 町 〇 〇 〇 〇 〇 〇 〇 — — — — — — — — — — — — — — 魏 ( ( ( ( ( ( ( ( ( ( ( ( Increased to ·, which represents the occupational pressure (the normal overvoltage of the scale battery 200822484 is about the cap), then the battery enters the fixed voltage (9) secret time, CV) charging mode. In this mode, the charger remains at voltage v〇v. When the charge current is reduced to a predetermined minimum value, such as 5 touches, the charging program terminates. In the cv charging mode, the charger must accurately adjust the voltage to v〇v (with an error of 5 (four)· _)' or the charging current will not gradually decrease with increasing battery power. If the 'charge output is greater than V〇v, then overcharging of the battery will occur, which can lead to safety issues for the battery. A conventional circuit 10 that implements pre-charging is shown in FIG. 1B. A Metal 〇xide 10 Semi (10) Field Effect Transistor (M〇SFET) 12 in series with a resistor (Rpre) 14 is used for precharging. At the time of pre-charging, the Field Effect Transistor (FET) 16 is turned off, and the pre-charging FET 12 is turned on. Therefore, the precharge current is roughly determined by the voltage difference between the charger input voltage VPACK+ and the total cell voltage VceU divided by the series resistance (Rpre) 14. When there is an AC converter (not shown in the figure and the voltage is +1 south of the cell voltage Vce11, charging or pre-charging will start according to the initial voltage of each cell. If the voltage in any cell is lower than At the threshold voltage Vw, the battery pack will enter the pre-charge mode. Otherwise, normal charging will begin.

Those skilled in the art will recognize that circuit 1A of FIG. 1B includes a battery monitor IC 20 that includes circuitry for monitoring the electrical 20 voltage and current of each cell (cell1, Cell2 ".Cell 4) in battery pack 2. The circuit can include a switching network 24 for sampling each cell voltage. To control the operation of the pre-charged MOSFET 12, the conventional circuit 1 includes a comparator 26 that can compare a certain voltage reference source 28 through the switch 30 ( Vuv) with each cell voltage. However, the circuit shown in Figure 1B has the drawback of requiring an additional power m〇sfet (ie, MOSFET 12) and resistor (Rpre) 14, which adds extra cost and 25 200822484 adds the area of the Printed Circuit Board (PCB). In addition, in this circuit topology, the lower cell voltage results in a larger precharge current. Moreover, the precharge current increases with the cell voltage. The reduction means that it takes longer to complete the pre-charging. In addition, the value of the resistor (Rpre) 14 is usually fixed, and the maximum and minimum values of the pre-charging current are usually fixed as well. This cannot be adjusted to provide different battery pack needs. _ Another drawback of this circuit topology is that battery pack 22 and MOSFETs are easily damaged under abnormal conditions, such as VPACK+ terminal shorted to VPACK-end, or external The charger is reversely applied to the VPACK+ and VPACK- terminals. In this topology, the discharge FET 18 is turned on to allow discharge or is turned off and cannot be discharged. When the discharge FET 18 is turned on, if an abnormality occurs, from the battery pack 22 The large current flowing out flows through the discharge FET 18 and the charge FET 16 ' which will in turn destroy the battery pack 22 and/or the MOSFETs. Further, the battery pack 22 is removed from the electronic system, for example, placed on a rack, The discharge FET 18 can be turned off to protect the battery pack 22 from abnormal conditions. However, since the discharge FET 18 is turned off, the battery pack 22 cannot immediately supply power to the electronic system when the battery pack 22 is inserted back into the electronic system. A mechanical or electronic circuit is therefore required to inform circuit 10 to turn on discharge FET 18. Additional mechanical methods or electronic circuits 2 will increase the complexity, price, and/or size of circuit 10. The battery pack 22 will still be damaged due to abnormal conditions after being inserted into the electronic system. The conventional method for protecting the battery pack 22 is to turn off the discharge FET 18 to avoid generating a large current when an abnormality occurs. The discharge FET 18 is turned off. After a predetermined time, for example 30 seconds, the discharge FET 18 is turned back on. If an abnormal condition persists after the discharge FET 18 is turned back on for 2 s, a large current will flow through the discharge FET 18 and trigger the battery pack tampering mechanism again. Therefore, the discharge FET 18 is turned off again. Otherwise, battery pack 22 200822484

10 15

20 will operate in the normal discharge mode as the discharge FET 18 is turned on. However, if an abnormal condition exists - a period of time, a large current will continue to flow through the battery 18, which will eventually destroy the battery pack 22 and/or MOSFETs. Therefore, there is a need for a circuit and method for performing a charge and/or a current discharge. SUMMARY OF THE INVENTION In an embodiment, the present invention provides a green color for protecting a battery pack from large current overcurrent conditions. Wealth pure silk _ _ control the students - the step of the signal and if the large current overcurrent occurs, under the control of the control signal - the surface of the turbulent discharge. The job stream can prevent large currents from circulating from the battery pack. In another example, the present invention provides another method of protecting a battery pack from current overcurrent conditions. The method includes the steps a) when a large current overcurrent condition occurs, the pay-discharge switch; b) the -switch control circuit generates a control signal having a pre-$ and a large level; c) A turbulent discharge current is generated under the control of the control signal, the lion discharge current is - the critical current is turned and the large current of the battery pack is circulated; d) the detection is based on the turbulent discharge current, the critical current level, and the preset maximum level Whether the current overcurrent condition still exists; e) if there is still a large current overcurrent condition, then steps a) to d) are repeated; and f) if the large current overcurrent condition is eliminated, the discharge switch is turned on.

[Embodiment] FIG. 2A shows a trickle precharge circuit 1 (8) according to an embodiment of the present invention. In this embodiment, two MOSFETs 104 and 102 (charge FET (CHGJET) 25 and discharge FET (DSG-FET)) are used. In this embodiment, the charge FET 104 and the discharge FET 200822484"

10 15

20 102 is primarily described in a back-to-back series arrangement. In the trickle precharge mode, the electrical FET 102 is off (non-conducting), but if the charge j?ET 104 is turned on (on) the current still flows through its body diode (l^y diode) to the battery cell . If the charge FET 104 is turned off, no current flows into or out of the battery cell. In addition to the two MOSFETs, the circuit 100 can also include a reference diode (di) 110, a discharge driver 106, a charge driver 108, and a reference current source (Iref) 112. Each of the charging driver 1〇8 and the discharging driver 1〇6 includes a respective comparator. In the normal charging mode, the switch (K1) 114 and the switch (1 (2) 116 are set to position 2. At this position, a charging driving voltage CHG is driven to be equivalent to the reference voltage CHG-REF, the reference voltage CHGJREF The charge FET 104 can be fully turned on. Therefore, the reference voltage CHGJREF is selected according to the startup requirements of the charge FET 104. In the trickle precharge mode, the switch (K1) 114 and the switch (K2) 116 can be set to position 1. When AC is turned When the voltage regulator is connected, the voltage VPACK+ will rise. The charge FET 104 can be driven to the saturation region by the charge driver 108, which also means that the charge 104 can be used as a variable resistor, and the trickle charge current can flow through the charge, fet1〇4. The charge driver 108 adjusts the charge FET 104 such that the voltage Vc is equal to Vd, which is determined by the diode (D1) 110 and the reference current source (Iref) 112. Vc is the voltage at the junction between the MOSFETs 102 and 104. yc can be set to charge. The negative input (-) of the comparator in driver 108, while Vd (determined by Iref and di) can be set to the positive input (+). The output signal CHG is Vd-Vc. When vc is almost equal to Vd, charging driver 108 of The comparator gain is selected such that a large round of output is sufficient to drive the charge FET 104 to operate in the saturation region. Thus, the charge driver 1 〇 8 can compare the Vc and the fixed signal Vd during the precharge period. The DC current flowing through the diode (Dl) 〇 is given by: 25 200822484

Iref = Al*ISl*(exp(Vdl/Vt)-l) e where A1 is the area of the body (10)110, IS1 is the body (D1(10) early reverse saturation current, VdUVcen, is the diode (D1) The voltage across the 11 , is the diode threshold voltage. 5 The DC current of the body of the discharge FET 102 is given by:

Ipch = A2*IS2*(exp(Vd2/Vt)-1) where A2 is the joint area of the body body, the body is the body 4 body unit reverse saturating, and the current '(four) c-VceU 'is the discharge FET body 4 body Pressure drop across the ends. (5) and IS2 are determined by the type of semiconductor selected. If the sum and & are forced to be true, then the precharge current must be proportional to the reference current of 1, which is given by:

Ipch = A2/Al*(IS2/ISl)*Iref is preferable, although it is not necessary for the present invention, usually due to the requirement of low turn-on electric current capability, the charging _g2 mechanically refers to the body of the G4. A2 is usually relatively large. At the same time, in order to save the wafer area, the 15 area A1 of the body (10) ιι〇 is small. Therefore, since Μ is much larger than A1, - small current Iref (tens of micro women) can be used to control a large current (tens to hundreds of milliamps). 2B shows a thirsty discharge circuit 2A in accordance with an embodiment of the present invention. This embodiment is similar to the circuit 1〇0 described in Fig. 2A except that the reference current source (丨) 112 and the diode (m) no are coupled to the discharge FET 102 terminal. During the turbulent discharge period, the charge fet 20 1〇4 is turned off. The choke discharge current flows through its body diode. The working principle of the circuit 200 Please refer to the detailed description of Figure 2A. FIG. 3A illustrates a trickle precharge circuit in accordance with another embodiment of the present invention. In this embodiment, the charge FET 302 and the discharge FET 304 are arranged in series face-to-face rather than in a back-to-back arrangement (as shown in Figure 2A). The embodiment of Figure 3A also includes a reference diode (D1) 310. In this embodiment, a charge driver 306 can be controlled by switches 200822484 j (ΚΙ) 314 and switch (K2) 316. In the normal charging mode, switch (ΚΙ) 314 and switch (Κ2) 316 can be set to position 2' so that the gate voltage of charge FET 302 is driven to clear, fully turning on charge FET 302. In the trickle precharge mode, the discharge fet 3〇4 is turned off, and the 5 switch (K1) 314 and the switch (K2) 316 are set to position 1. Thus, the charge drive p 306 acts to adjust the charge FET 302 and thereby force the voltage vc to be substantially equal to Vd. Under forward bias conditions, the DC current of the body 2 (D1) 310 is given by:

Iref=Al*ISl*(exp(Vdi/Vt)-1) 馨中 A1疋二^ Although the body (D1) 310 is connected to the area, IS1 is a diode (di) 31〇ίο unit reverse saturation current, V di Two VPAK+ - Vd, is the cross-pressure of the diode (D1) 310,

Vt is the diode threshold voltage. The dc current of the body 4 of the discharge FET 304 is: Ipch=A2*IS2(exp(Vd2/VtH) where A2 is the body junction area, is2 is the body diode unit reverse saturation 15 current, Vd ^VPACK+ - V. is the voltage across the body of the discharge FET body. IS1 and IS2 are determined by the selected semiconductor type. If the Vc is forced to be the same, then the thirst_current precharge current is given by:

Ipch II A2/Al*(IS2/IS1)*Iref FIG. 3B shows a choke discharge circuit 4 (10) according to another embodiment of the present invention. This embodiment 20 is similar to the circuit 30A shown in FIG. 3A except that the reference current source (Iref) 312 and the diode (D1) 310 are coupled to the charge FET 3〇2 terminal. During the trickle discharge, the charge FET 302 is turned off and the discharge current can flow through the body diode of the charge FET 3〇2. The operation of circuit 400 is described in detail with reference to Figure 3A. In order to speed up the ship pre-charging process, the trickle pre-charge current Ipch can be quickly adjusted according to the battery voltage. The higher the battery voltage, the greater the turbulent precharge current of 11 200822484 by editing the reference current Iref. As is well known to those skilled in the art, the programmable current source of Figure 4 is suitable for generating a reference current based on the battery voltage. > Another-flow pre-charging circuit 5A is also described in FIG. In this embodiment, charge FET 504 and discharge FET 502 are primarily described in a conventional back-to-back series arrangement. In the trickle precharge mode, the discharge FET 502 is turned off (non-conducting), but if the charge FET 504 is turned "on", current is still flowing through its body diode cell. If the FET 504 _ is charged, then no current flows in or out: the core. /甩 This embodiment further includes a reference resistor, a discharge driver 5〇6, a charge drive 10 dynamics 508, and a tea test current source (Iref1) 512. Charge driver 508 and discharge driver 506 can include respective comparators. In the normal charging mode, switch αι) 520 and switch (Κ2) 518 are set to position 1. In this position, a gate drive voltage CHG is driven to be equal to - the reference voltage chg - qing to fully turn on the charge bribe 504. Therefore, the reference voltage CHG_pgp should be selected according to the startup requirements of the charging FET 504. 15 Switches κι and K2 are connected to Node 2 when required, shoulder charging (ie, current drain pre-charging). Thus, the input of the charge driver 8 odorizer is the voltage drop across the resistor (1) and R1 (generated by Irefl 512) (1). The gain of the comparator in charge driver 508 should be designed to be large enough (10) such as _) so that the voltage drop generated by the resistor R1 is approximately the same as the trickle charge current & Pressure drop. The trickle precharge current is given by: I pch = I ref 1 *R1 /Rsens where ^efl is - a programmable reference current source. Usually very small (e.g. 10 to 20 milliohms)' while R1 can be chosen to be in the range of 1 ohm. Therefore, the ratio of R1 25 (R1/Rsens) can be very large, so that a relatively small thirteen current precharge current Ipch can be generated with a small reference of 200822484 current 1refl. In the embodiment of Fig. 4, in the pre-flow mode, the discharge can be fully turned on, thereby eliminating the diode forward bias between VPACK+ and the battery voltage. In this mode, the switch (K4) 514 and the switch (K3) 516 can be set to the 5 position 1 to drive the discharge fET 5〇2 with the discharge reference voltage DSG_REF to fully turn on the discharge FET 502. Please continue to refer to FIG. In the normal arbitrage mode, _(10) 516 and switch sag (K4) 514 can be respectively connected to the node. Thus, the discharge driver 5 〇 6 is set as the - snubber, and the drive discharge FET 5 〇 2 is fully turned on. When in the thief discharge mode, Chuan, (K3) 516 and switch (K4) 514 can be connected to node 2. Due to the back-up of the discharge drive dynamics 506, the voltage drop due to the flow of the resistor 尬 by iref2 approximates the voltage drop caused by the flow of the sense resistor Rsens. Thus, the choke discharge current is given by:

Idsg=Iref2^R2/Rsens where 1:2 is a programmable reference current source. Usually Rsens can be very small, 15 so that the ratio of R2 to Rsens (R2/R_) can be very large, so a small reference power /a Iref2 can produce a relatively large turbulent discharge current idsg. Since the current direction is reversed during discharge, the voltage across the sense resistor Rsens and the voltage across R2 have opposite polarities. Therefore, the polarity inversion circuit 522 is used to invert the polarity of the current flowing through Rsens. In this embodiment, during trickle charging, the discharge FET 5〇2 can be fully turned on so that the forward bias of the diode between the VPACK+ and the battery voltage is eliminated. Similarly, during trickle discharge, charge FET 504 can be fully turned on to eliminate the forward bias of the diode between the bank voltage and VPACK+. In the present invention, once the MOSFETs and the NMOS are fixed, 丨_ can still be adjusted by the weighted tea reference current source (Iref) 112, 312, 510, and/or 512. A circuit topology of a programmable reference current source is depicted in FIG. The circuit of Figure 5 is used for 13 25 200822484 to generate a current ^ with a ratio current mirror (ratiQ e_nt mirrQr). Of course, in addition to the circuitry shown in Figure 5, the programmable reference current source is: and can be presented in a variety of modes. Figure 6 depicts a pre-charge and drain circuit _. In this embodiment 5, the charge FET 604 and the discharge attachment 6〇2 are arranged in series in back-to-back or in a face-to-face arrangement as described above. In this embodiment, a digital/analog converter circuit (DAC) can be used to generate the sigma drive voltage, as described more fully below.骜 This embodiment includes an analog/digital converter circuit (ADC) 614, a control unit 10 612, and a control loop formed by a digital/analog converter, circuit (DAC) 616. Current flowing through the sense resistor (Rsens) 618 is received by the ADC 614. Next, 胤 614 can generate the _ 峨 峨 并且 and transmit these signals to control unit 612. In the operational port, if the current flowing through the sense resistor (Rsens) 618 is less than a preset threshold value, control unit 612 can send data to DAC 616 to increase the corresponding FET drive voltage. Conversely, the control unit (10) will send data to the DAC 616 to reduce the FET drive voltage until the sense current and the preset current are approximately equal. ► In the positive charging or discharging mode, the driving voltage of the charging FET 6〇4 and the discharging cis6〇2 is high at this time, because the 匸 is disabled (controlled by the DAC-EN signal connected by c). (High). The charging driver drives the gate of the charging FET _ 2 〇 to a value of CHG-® and fully turns on the charging 604. The discharge driver 606 drives the gate voltage of the discharge FET 602 to the DSG-gel value and fully turns on the discharge FET 602. In the >month flow discharge mode, the switch (K1) 620 is connected to the node 1. The discharge driver 606 is de-asserted (DSG-ΕΝ is low level) and has a high impedance output, and the conductive nuisance of the discharge FET 6〇2 25 can be controlled by the DAC 616. Thus, discharge FET 602, senser 14 200822484 Rsens 618, ADC 614, and DAC 616 can form a control loop. By controlling the turn-on resistance of the discharge FET 602, the present embodiment is capable of adjusting the choke discharge current to a preset value (which can be edited to the control unit 612 in advance). The turn-on resistance of the M0SFET can be adjusted by adjusting the gate drive voltage. In an embodiment, if the required choke discharge current is set to [ltd], the corresponding control code for controlling the listening circle can be obtained using the Successive Approximation Register (SAR). The highest bit of the DAC (M〇st

The Significant Bit (MSB) is first set to a high level. If the current isen of the sense resistor (Rsens) 618 is greater than Itd, the MSB is set to a low level (1〇w), otherwise the MSB will be held. High level. The second highest bit is then set to a high level, and if Isen is greater than Itd, the second highest bit is set to a low level (1〇w), otherwise the second highest bit will be held at a high level. This successive approximation will continue until the Least Significant Bit (LSB) of the MC is set. The corresponding control code can be stored in the temporary memory (not shown) and can be accessed by the control unit 612. 15 If 1 td is a fixed value set for a given battery pack, then the control code is also a fixed value. Whenever the f-stream discharges, the control element 612 can send a programmed code to the DAC 616, so the battery pack can transmit Itd to an external load. If the 敎 discharge current needs to be adjusted, the above control loop can be 相β〇8 2 or this is lost. The difference is that the thirst discharge current will flow through the charge FET 604 or its body diode, respectively. The fin« ΐίί charging mode 'switch (10) 620 is connected to node 2. The charging driver lost the moon (CHQ_EN is low). The conduction state of the charging FET 6〇4 can be composed of 25 fiU 〇 ^ ^ ΡΕΤ 604 ' ^ ^ Rsens 618 > and the DAC 616 system constitutes a control loop. By controlling the opening of the charging FET ship 15 200822484, this embodiment can adjust the thirst charging current to a preset value. The precharge current is usually - fixed value. In this mode, the present embodiment can generate a _ control code (using the SAR method described above) and store the control code in a memory. For turbulent precharge currents, the value can vary from an upper limit to a lower limit. Therefore, control code 5 is also in CTCH (representing the upper limit of the turbulent precharge current) and CTCL (representing the turbulent precharge current). The change between the lower limit values) allows the trickle charge current to be adjusted accordingly. In the charge mode, the discharge driver β〇6 can also be enabled or disabled. The difference is that the trickle charge current will flow through the discharge FET 6〇2 or its body diode, respectively. The trickle discharge mode described above can be further applied to achieve battery pack short circuit 1 〇 / over current protection. When the battery pack is removed from the electronic system (that is, when the battery pack is in an idle state), the first payoff is that there is _. Unlike the conventional method of keeping the discharge FET 602 off, the first embodiment sets the discharge cis 6 〇 2 to a controllable conduction state. When the discharge FET is in a controlled conduction state, even if a short circuit condition occurs, for example, the 邙 邙 + terminal is shortly connected to the ypACK-u (four) 6 〇 2 opening resistance block. Similarly, (iv) the flow of high current surges to prevent health. In fact, when a short-circuit/overcurrent condition occurs, the 涓/bump current will flow through the FET 6〇2, and the choke discharge current can be set to a pre-compensation to ensure the safety of the battery pack and the M〇SFET. A choke discharge current, such as 1 〇〇, can drive an external control unit embedded in the electronic system (which is not the control unit 612 shown in Figure 6). When the battery pack is inserted into the electronic system, the embedded control unit can detect the insertion of the battery pack and notify the battery pack of the normal discharge mode. In this way, additional mechanical methods or electronic circuits are required to detect the insertion of the battery pack. This does not tear the mechanical method or electronic circuitry to detail and inform the insertion of the battery pack. However, when the battery pack is inserted into an electronic system, the first embodiment does not further provide battery short/overcurrent protection. Therefore, the first embodiment is only available when the battery 16 200822484 group is taken from the electronic money. f Flow lags are described as effective when entering the electronic system. At the beginning of the pool group: (for example, 'the battery pack is taken out from the electronic system'), or: the second battery type (for example, the battery pack is inserted into the electronic system, then the battery pack will stay in the electricity === Then fine 6 immediately closes the discharge touch η β to turn off within a few microseconds. Then, in the step hire, if the discharge FET gate is a preset time, for example '25 seconds, unlike the traditional immediately complete 15 20 ' : Field discharge shun 602 is in a controlled conduction state. In step 71, as the discharge current flows to the FET 602, the battery pack will operate in the thirst discharge mode. If the ς pre-timing time has not expired, the discharge FET 6Q2 Still in the state of remuneration. The technician will recognize that in order to implement step 7〇8, the implementation 2 shown in Figure 6 includes a battery management firmware and a timer. The battery management firmware can monitor the timer. With - preset time (eg 25 seconds). If short circuit / over power condition 4 occurs, the battery management firmware will inform the discharge FET 6 〇 2 has been turned off, then start the scale. If the preset time of the device is terminated, The battery management object will know the discharge FET 60 2 has been turned off for a preset period of time. In the stream discharge mode, the DAC 616 of Figure 6 provides a gate drive voltage to the discharge FET 602. The drive of the gate drive voltage causes the discharge FET 6〇2 to operate Controllable conduction state. By adjusting the gate drive voltage, the discharge resistor 25 of the discharge FET is adjusted 'so that the choke discharge current flowing through the discharge 1^ 602 is adjusted accordingly. 17 200822484 The unit can include the following substeps Initially, in control _ , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , It will be readily understood by those skilled in the art that the turn-on voltage of the discharge FET 602 is gradually decreased as the gate drive voltage is increased, so that the flow of electricity fet = two discharges is gradually increased. The voltage of each of the gates is increased, corresponding to The current is detected at both ends of the resistor (R cloud) (10) and is then used to determine if the loop/overcurrent condition still exists. 15 20 In particular, in step 716, by comparing the thief discharge current with the pre- Set the current, :4 0 pen safety, to determine whether the short circuit / over current condition is still present. If the current is greater than the preset current, it can be inferred that the short circuit / over current condition still exists. Next, the system shown in 6 is restarted through the recommended operation of the step The battery pack's thief discharge current is less than the preset current. In step 718, the gate drive: the pressure will be compared with the preset maximum control level. In fact, the voltage between the poles will not increase without limit. And will be limited to the preset maximum control level. In step 718, the gate drive voltage reaches the preset maximum control level, it can be inferred that the short circuit/overcurrent condition no longer exists, and the battery pack will return to the idle mode or Normal discharge mode (step 702). Otherwise, the battery pack will repeat steps 714, 716, and 718 until the step determines that the short/overcurrent condition exists or step 718 determines that the short/over current condition is absent and exits the choke discharge mode. The preset current mentioned here is set by considering the power dissipation performance of the MOSFET. For the battery pack with four cells shown in Figure 6, the preset current can be set to 40 mA. Therefore, the maximum power dissipation of the discharge FET 602 is close to 68 mA, which is a safe value for the power MOSFET. In addition, the voltage at the VPACK+ terminal can be used to determine whether the short/over current condition is 18 25 200822484

10 15 exists. In step 716, the voltage at the VPACK+ terminal is detected and, for example, 100 millivolts. If you delete the purchase, the default voltage is 2, and _ is there. Otherwise 'in step 718, the gate drive voltage is broken. Xia _____: Hey. Set by hole and internal impedance. For the embodiment of Figure 6, the preset voltage is set to millivolts, which is a preferred compromise between short-circuit/overcurrent conditions and noise-critical. The weight of the 丨P resistance is shown from Fig. 1A', we know that during the pre-charging period and during the constant voltage (cv) charging, the electric current needs to be controlled. In conventional circuits, 'required-additional pre-charging is followed to control the pre-charging current. In such a conventional circuit towel, the cv charging must rely entirely on the charging device to adjust the charging voltage to Vgv, and then the charging current will be decremented. In the present invention, the pre-charging function can be implemented without adding additional pre-charged FETs. In addition, in order to increase the charging process, the precharge current 1 can be easily adjusted according to the battery voltage. The higher the battery voltage, the greater the power supply through the stylized reference current lrcf, the control code method described in Figure 2A, Figure Μ and Figure 4 or Figure 6.

20, more advanced, y is also as described in 4 people, the turbulent precharge current control method can also be used during the cv charging period, during which the pre-charge circuit must be based on the battery (4) Stream current. Thus, the decrement of the cv charging current does not need to rely on the charger to accurately adjust the voltage ν 〇 ν. Thus, several embodiments provided by the present invention are expected to require expensive, accurate voltage filling. In fact, a simple AC chick can be shouted at the _ sub-electricity. Since (7) charging, even if the charging energy is set to % in the power, the current is limited to the pre-programmed secret current value according to the battery «. Therefore, the condition of overcharging does not occur. The charging current limit can be used as the second layer of overvoltage protection (through 19 25 200822484

10 15

20 The current limit is set to be slightly larger than the current value actually observed at the desired voltage _ or as the first layer of overvoltage protection (by adjusting the charging current until the precise desired voltage Vuv is obtained). With the trickle discharge performance of the present invention, better short circuit/overcurrent protection for the battery pack is possible. In the prior art, the discharge FET is fully turned on to allow or completely turn off to inhibit discharge. When the battery pack is taken from the electronic system, for example, on a shelf, the discharge FET remains in the on state to prepare to power the electronic button at any time. In this case, if the abnormal condition 'such as VPACK+ is shorted to the VPACK_ terminal, the liquid out of the battery will 'destroy the battery'; or the discharge FET remains off to prevent the battery from being damaged. Short circuit / over-current reading. Ant Wei made #电敝 was inserted into the county to prevent the battery to the secret. Need - Sharp method to inform the battery to clear the state of the FET. This will lead to customer inconvenience and increase costs. Also using the present invention, when the power/f subsystem is taken out, we can set the battery pack to the job placement mode. The ship's electrical secret can be chosen to be 100 mAh, when the battery pack is plugged into the electronic system tree enough to power the embedded control unit. The system of the 峨 control unit will then detect the presence of the battery and inform the battery 3 of the normal discharge mode. As the discharge FET limits the current to a preset out-of-discharge (10) mA, even if the face is shorted to mcK, the high-current tera-tube battery is taken out of the electronic system or from the electronic system. The battery pack can be protected under abnormal conditions, for example, short 3 = put_ slave is controlled to be on, rather than the traditional yarn I king. Therefore, the battery pack will be operated in mode. With the gradual increase of the driving voltage with 20 25 200822484, the corresponding turbulent discharge current also increases accordingly. In this process, if the corresponding choke discharge current is greater than the preset current, assuming 4 amps, it can be inferred that the abnormal condition persists, so the discharge FET will be turned off again and the battery pack will repeat the above operation. If the gate drive voltage is increased to a predetermined maximum control level, 5 and the corresponding choke discharge current has not reached the preset current, it can be determined that the abnormal condition has been eliminated and the battery pack can operate in the normal discharge mode. Choke discharge and trickle charge performance are very useful for supporting multi-battery systems. * When the hair subsystem needs more power and more features, multiple battery packs will become more powerful. When multiple battery packs are discharged, they can provide more power to the system, and because multiple battery packs in parallel will also reduce the internal impedance of the battery to improve efficiency. However, the simultaneous discharge of the battery pack has a strict premise that these batteries must have exactly the same voltage. Otherwise, even if only two battery packs have a small voltage difference, false: 10 volts 'Because the resistance of the power busbar is small, assuming 2 milliohms, the power busbar will also have a large current, 5 amps. From a battery pack 15 having a higher voltage to a battery pack having a lower voltage. In fact, it is difficult for multiple battery packs to have the same voltage, because the battery pack voltage varies with the discharge current. It is difficult to make sure that the two battery packs have a very accurate one to monitor the battery voltage. Voltage. With the Wei flow discharge Wei _ use, _ can bribe the following _ question (we take two battery packs as an example). 20 One system has two battery packs, battery pack A and battery pack B. Initially, the voltage of battery pack A is souther than the voltage of battery pack B; battery pack A is first powered to supply power to the system, and the voltage of the battery is gradually reduced. The discharge FET of battery pack B is turned off to prohibit the discharge. Although the battery pack's power is repeatedly reduced to the same voltage as the battery pack, we set the battery pack to ί. If we turn the battery pack 25 into the > monthly flow charging mode, the discharge FET can be fully turned on, and the charging FET is driven to the saturation region of 200822484 and the charging FET is used as a current limiting resistor; if we set the battery pack B to In the trickle discharge mode, the charge FET is fully turned on and the discharge FET is driven to its saturation region and the discharge FET is used as a current limiting resistor. Based on more safety factors, we can convert the f-stream filling code Ctc (representing thirst charging) or the current-discharge control code CTO (representative/office discharge) 5 into a small current value. Therefore, the equivalent resistance of the charge cis or discharge becomes larger. Since the battery pack A is discharged but the battery pack B is in the idle mode, the voltages at which both of them are measured are the same, and in fact, the power of the battery pack A will be souther than the voltage of the battery pack B. Therefore, the battery pack A will charge the battery pack β. In addition, the charging current is limited by the charging FET (if the battery pack B is set to a sinusoidal charge or a discharge FET (if the battery pack B is set to the thirst discharge mode), the control value is controlled by the control code. (3) or - decision. We also monitor the charge through the battery pack B. When the voltage difference between the tests A and β becomes m, the charge from the battery pack A to the battery pack B will become electric 15 20 25 When it is less than the predetermined value, suppose that we can convert the battery pack β裕2 = or the 渭流放赖式 to the normal arbitrage type. The heart month catches the _ way and the open programmable code, pre-charge and / Lai flow discharge electricity, age scales and Shaohao rate to complete the pre-charge. The charge of the silk battery battery}, in the 2A and 2B, to open the coffee ^ and ride the battery monitoring 1C control, to Will be programmable: two f3 and K4) can be through the charging mode or normal charging mode ^ charging circuit settings can be pre- _ individual components and / or integrated circuit:: ==: can be ^ electric surface can be prisoner d = 吏 use the specific circuit mentioned here to extend the wheel to the temple 4). Limited, other electric kettles 200822484

[Simple description of the diagram] The i-way can also have many circuit variations and modifications. All of these improvements are ought to be in the present invention, although those skilled in the art are aware of the following detailed descriptions.

A, 4, guide 匕 Γ / Γ疋 me. Other features and advantages of Qiao Thumbing will be more clearly described in the following detailed description, and the material of the present invention is changed to the figure of the present invention and wherein: FIG. Schematic diagram of current and voltage during battery charging process. FIG. 1B is a conventional battery precharge circuit. 2A is a trickle precharge circuit in accordance with an embodiment of the present invention.囷2B疋 A current-discharge circuit according to an embodiment of the present invention. Solid 3A A trickle precharge circuit in accordance with another embodiment of the present invention. The figure is a choke discharge circuit according to another embodiment of the present invention. A precharge circuit according to another embodiment of the present invention. Figure 5 is an embodiment of a programmable current source. Figure 6 is a diagram of a trickle precharge and choke discharge circuit of an embodiment. Figure 7 is a control flow diagram of battery pack short circuit/overcurrent protection in accordance with one embodiment of the present invention. [Main component symbol description] 10 : Precharged conventional circuit 12 : Precharge field effect transistor (FET) 14 = Resistor

16: Charging FET 23 200822484 18 : Discharge FET 20 : Battery monitor IC 22 : Battery pack 24 : Switching network 5 26 : Comparator 28 : Constant voltage reference source 30 : Switch 50 : Charging profile Φ 100 : Turbulent advance Charging circuit

Οο··Discharge FET 104 ··Charge FET 106 :Discharge Driver 108 :Charge Driver 110 ··Reference Diode 15 112 :Reference Current Source 114,116 :Switch φ 200 : Choke Discharge Circuit

300: trickle precharge circuit 302 ··charge FET 2〇304: discharge FET 306: charge driver 310: diode 312: reference current source 314, 316: switch 400: choke discharge circuit 25 200822484 500 : turbulence advance Charging circuit 502 · discharging FET 504 : charging FET 506 : discharging driver 5 508 : charging driver 510 : reference current source 512 · dad test current source 514, 516, 518, 520 : switch 10 522 : polarity inversion circuit ίο 600 : Trickle precharge and choke discharge circuit 602: discharge FET 604: charge FET 606: discharge driver 608: charge driver 15 612: control unit 614: analog to digital converter (ADC) 10 616 · digital analog converter (DAC) 618: sense resistor 620: switch 2〇700: control flow chart 702~718: step 25

Claims (1)

200822484 X. Patent application scope: 1 · A method for protecting a battery pack from a large current overcurrent condition, comprising the steps of: generating a control signal in a switch control circuit; and if the large current overcurrent occurs And generating a current discharge current under the control of the control signal, wherein the trickle discharge current can prevent the large current from flowing from the battery pack. 2. The method of claim 1, further comprising: adjusting the choke discharge current under the control of the control number. 3. The method of claim 2, wherein the step of adjusting the turbid current discharge current further comprises: setting a discharge switch to a controllable conduction state under the control of the control signal. 20 adjusting a resistance value of the discharge switch according to the control signal; and adjusting the choke discharge current according to the resistance value of the discharge switch. 4. The method of claim 4, wherein the surface current discharge current is capable of providing power to an external control unit embedded in the electronic system. 5·= The method of item 4, the step further comprising the step of generating a normal discharge current under the control of the external control early 70. 6.1 methods for protecting a battery pack from current overcurrent conditions, including the following steps: a) When a large current overcurrent condition occurs, the switch is turned off; the control circuit generates a control signal, and the control signal has Pre 25 c) generating a turbulent discharge current under the control of the control signal, the turbulent discharge electricity 26 200822484 5 10 15 20 current has a critical current level and can prevent the large current from flowing from the battery; d) detecting the large current overcurrent according to the choke discharge current, the critical current level, and the preset maximum level Whether it exists; e) If the large current overcurrent condition still exists, repeat steps &) to illusion; and Ο if the large current overcurrent condition is eliminated, turn on the discharge switch. 7. The method of claim 6, further comprising the steps of: setting a timer; and generating the choke discharge current when the timer expires. The method of claim 6, wherein the step of generating the thirst discharge current further comprises setting the discharge switch to a controllable conduction state under control of the control signal. 9. The method of claim 6, further comprising adjusting the choke discharge current based on the control signal. 10. The method of adjusting the shed flow discharge current according to the method of claim 9, further comprising: sizing a resistance value of the discharge switch according to the control signal, and according to the discharge _ the resistance _ Wei thief discharge current . 11. = Please refer to the method of item 6 of the patent scope, wherein if the turbulent discharge = at least the ploughing of the current, the gambling still exists. 12. = The method of claim 6, wherein the large current overcurrent condition is eliminated if the control signal is found to be at the maximum level. 13. The method of claim 6, wherein step (4) further 27 25 200822484 includes: a) detecting the choke discharge current; b) comparing the choke discharge current to the critical current level, C) If the choke discharge current is less than the critical current level, comparing the control 5 signal with the preset maximum level; d) if the control signal is less than the preset maximum level, increasing the control signal 3, And e) repeating steps a) through d) if the choke discharge current is less than the critical current level and the control signal is less than the predetermined maximum level. The method of claim 6, wherein the step (4) further comprises: a) detecting a voltage at a positive end of the battery; b) comparing the voltage with a threshold voltage level; c If the voltage is at the threshold voltage level, comparing the control signal with the 15 preset maximum level; d) if the control signal is less than the preset maximum level, increasing the control signal, and e) If the voltage is above the threshold voltage level and the control signal is less than the predetermined collocation level, steps a) through d) are repeated. 20 丨 5. The method of claim 4, wherein the high current overcurrent condition still exists if the voltage is at most equal to the threshold voltage level. 28