CN101567554A - Battery pack protective circuit applying micro-electromechanical system (MEMS) switch - Google Patents
Battery pack protective circuit applying micro-electromechanical system (MEMS) switch Download PDFInfo
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- CN101567554A CN101567554A CNA2008100528360A CN200810052836A CN101567554A CN 101567554 A CN101567554 A CN 101567554A CN A2008100528360 A CNA2008100528360 A CN A2008100528360A CN 200810052836 A CN200810052836 A CN 200810052836A CN 101567554 A CN101567554 A CN 101567554A
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Abstract
The invention relates to a battery pack protective circuit applying a micro-electromechanical system (MEMS) switch, which can be ued for a rechargeable battery or a battery pack, for example a lithium battery pack used for a notebook computer and a rechargeable protective circuit of an electric bicycle or an electric car. The charge and discharge protective circuit comprises a battery, an analog front end (AFE) circuit of a charge and discharge control circuit of a battery pack, a micro-control unit (MCU) and one or more micro-electromechanical system (MEMS) switches. The invention can reduce static power consumption of the batter or the battery pack in a process of charging and discharging, provides higher degree of isolation in a disconnection process and improves the density of integration of a charge and discharge circuit.
Description
Technical field
The invention belongs to battery protecting circuit, particularly a kind of battery pack protective circuit of applying micro-electromechanical system (MEMS) switch.
Background technology
At present; the equipment of the high-power rechargeable batteries of needs (group) such as notebook computer, electric bicycle and electric automobile has obtained extensive use; and the life-span of these rechargeable batteries has directly determined the continuous working period of equipment; therefore how effectively high power battery to be carried out charge and discharge, and the discharge process that automatically liquidates manages, shows and protection becomes hot subject.Existing battery (group) charge and discharge protecting control circuit can be realized effective control and the protection for the high power battery charge and discharge process, and battery (group) the charge-discharge protection circuit functional block diagram of tradition employing MOS field-effect transistor (MOSFET) switch as shown in Figure 2.It mainly comprises the front-end detection circuit (AFE) of a simulation, a microcontroller (MCU), discharges and recharges control field effect transistor (MOSFET) and sensitive resistance.Current detection module convection current in the microcontroller is crossed the electric current of sensitive resistance and is surveyed, and when detecting the current overload that flows through battery or short circuit, sends an interrupt signal to MCU.The size of current battery electric weight can also be controlled and show to microcontroller, and send to AFE according to interrupt signal and to stop to discharge and recharge signal.AFE is according to the signal of microcontroller, opens or close to discharge and recharge field effect transistor accordingly.Because the electric current in the impulse electricity process is bigger, this electric current flows through any resistance all can produce bigger quiescent dissipation.Therefore, Don J Nguyen has proposed to remove the scheme of the sensitive resistance of gallon in 2007, adopt one or more hall effect sensor, utilize Hall effect to come detection flows to cross the electric current of battery or battery pack, eliminated the quiescent dissipation that sensitive resistance consumes like this.Generally speaking; these charge and discharge MOSFET is a discrete device, and this is because the switch mosfet of CMOS technological design at present can't satisfy the requirement of battery (group) charge-discharge protection circuit for low on-resistance and high working voltage and big operating current at aspects such as conducting resistance and operating voltage and electric currents.And the MOSFET of discrete device can satisfy the requirement for high working voltage and big operating current, but its conducting resistance is still bigger, and this conducting resistance is generally several ohms., the charging and discharging currents average current of the lithium battery (group) that notebook is used is about about 1A.Therefore under conducting state, switch mosfet institute power consumed can reach several watts magnitude usually.And for electric bicycle or electric automobile, the power consumption of switch conduction resistance consumption will be bigger.This switch mosfet generally adopts special process to make, and can't realize integrated with other control circuits.Therefore need more low-resistance switch, with the quiescent dissipation that reduces charge-discharge protection circuit and improve integrated level.
Summary of the invention
Technical problem to be solved by this invention is: the battery pack protective circuit that a kind of applying micro-electromechanical system (MEMS) switch is provided.Reach and reduce in the battery pack impulse electricity process, the big problem of quiescent dissipation under the charge and discharge switch conducting state, and improve the integrated level of whole protecting circuit as far as possible.
Technical scheme of the present invention is:
A kind of battery pack protective circuit of applying micro-electromechanical system (MEMS) switch is characterized in that:
A microcontroller MCU, be used for the current anomaly of charge and discharge process is detected and controls, when situations such as charging or discharge process appearance overload or short circuit, this testing circuit can send one group and characterize the unusual interrupt signal of charge and discharge, this moment, the CPU of microcontroller then handled for the interrupt signal that testing circuit occurs, and showed present charging and discharging state;
An AFE (analog front end) testing circuit AFE is used to microprocessor power supply, and control charge and discharge micro-electromechanical system (MEMS) switch is realized charging and discharging function for battery pack, and voltage swing on the battery is surveyed;
A sensitive resistance is used for charging or discharging current are surveyed;
One or more charge and discharge micro-electromechanical system (MEMS) switch charges to battery, battery pack or discharges with lower quiescent dissipation.
Carry out discharging and recharging of battery pack with one or more micro-electromechanical system (MEMS) switch.
Using a plurality of micro-electromechanical system (MEMS) switch series connection or parallel connection discharges and recharges.
With discrete device form, the some or all of battery that comprises micro-electromechanical system (MEMS) switch, the battery set charge/discharge protective circuit that realizes with the integrated circuit form.
Physical circuit is: the static micro-electromechanical system (MEMS) switch that connects two series connection at the negative pole end of battery pack, the negative pole end of battery pack connects the transmission line of first static micro-electromechanical system (MEMS) switch, first electrode of this first static micro-electromechanical system (MEMS) switch connects the transmission line of second static micro-electromechanical system (MEMS) switch, and first electrode of second static micro-electromechanical system (MEMS) switch is as the negative pole end output; Between the transmission line of each static micro-electromechanical system (MEMS) switch and first electrode and connect a diode, the positive pole of two diode utmost points links to each other; Positive terminal in battery pack connects sensitive resistance, the junction of each battery of the connection battery pack of the front-end detection circuit AFE of a simulation, and the front-end detection circuit AFE of simulation divides other to connect second electrode of two static micro-electromechanical system (MEMS) switch; The front-end detection circuit AFE of simulation connects microcontroller MCU; The sensitive resistance two ends connect microcontroller MCU.
Should use the battery pack protective circuit of micro-electromechanical system (MEMS) switch, this battery protecting circuit is applied to carry out battery protection in lithium battery, battery pack or other TunePowers, the battery pack.
Effect of the present invention is:
This characteristic feature of an invention is in charging and discharging process, can reduce the quiescent dissipation that battery (group) consumes, and the isolation of higher degree is provided in the disconnection process, and improves the integrated level of this charge and discharge circuit.
The characteristics of this structure are: 1, utilize the good mechanical property of monocrystalline silicon to solve the membrane stress distortion, solved the weakness of physical characteristics of materials difference; 2, adopt push-pull configuration to make contact point and transmission line spacing increase and be 2 times of initial separation, therefore obtain same isolation and can allow low tone distance between the drive electrode, thereby obtain lower driving voltage; 3, utilize push-pull configuration to solve the single armed beam and recover hypodynamic, switch life is increased greatly.
In the time of in being applied in battery (group) protective circuit; when this micro-electromechanical system (MEMS) switch sends charging or discharge signal according to the AFE end; add the driving voltage that needs between top electrode and the bottom electrode; movable beam is drawn under the electrostatic force of last bottom crown and is made contact zone and transmission line closure; micro-electromechanical system (MEMS) switch conducting, a charging in the battery pack or a switch closure in the discharge switch at this moment.According to the type difference of switch closure, battery (group) can be in charging or discharge condition.If AFE sends an opposite signal, both remove driving voltage and between other end top electrode and bottom electrode, added driving voltage, make drop-down contact point and the transmission line of making of movable beam disconnect, micro-electromechanical system (MEMS) switch disconnects, and the impulse electricity state of battery this moment (group) changes.
The technical scheme effect
Adopt switch mosfet to compare with tradition, adopting micro-electromechanical system (MEMS) switch is that quiescent dissipation is low and be convenient to integrated as the major advantage of charge and discharge control switch.The performance that table one has provided the switch mosfet that can buy in the market and micro-electromechanical system (MEMS) switch relatively, from table one as can be seen, the conducting resistance of switch mosfet is 1.6 ~ 5 ohm, and the resistance value of micro-electromechanical system (MEMS) switch is 0.16-0.35 ohm, and the quiescent dissipation of its conducting state can be expressed as:
Power＝I
2R
ON (1)
Therefore adopt micro-electromechanical system (MEMS) switch that the quiescent dissipation of switch conduction state is reduced to about 1/10th of MOSFET, thereby prolong the continuous discharge time of battery (group), reduce charging times, extending battery life.The lithium battery group of using with general notebook is an example, the battery nominal voltage of next notebook of ordinary circumstance is 10V, its specified electric quantity is 2000mA* hour, therefore its power is about 40W, calculate with average discharge current 1A, do not consider the to discharge conducting resistance of field effect transistor, this notebook can continuous firings two hours.With the NE3290MOSFET switch is example, and the power consumption of switch conduction resistance consumption is 5W, is about 1/8 of total power consumption, promptly will reduce about 15 minutes discharge time.Although the electric current of notebook charging process can be relatively littler, its charging interval president's is many, so its charging process is identical with the gross energy of discharge process consumption substantially.
And; this micro-electromechanical system (MEMS) switch can be well compatible with existing silicon technology; and then realization whole battery group charge and discharge protective chip is integrated; this can reduce external terminal (PAD) quantity of chip; reduce the operation of encapsulation process, and then improve the reliability of entire cell (group) protection system.
| Device name | Type | Conducting resistance/ohm |
| NE3290 | FET | 5 |
| Blackwell | FET | 1.6 |
| Raytheon | Micro-electromechanical system (MEMS) | 0.35 |
| Rockwell | Micro-electromechanical system (MEMS) | 0.22 |
| APPA-proj | Micro-electromechanical system (MEMS) | 0.16 |
Description of drawings
The charge and discharge protection circuit structure of the battery pack of Fig. 1, applying micro-electromechanical system (MEMS) switch
Fig. 2, tradition are used the charge-discharge protection circuit structure of MOSFET
The operation principle (switch off state) of Fig. 3, static micro-electromechanical system (MEMS) switch structure
The operation principle of Fig. 4, static micro-electromechanical system (MEMS) switch structure (switch closes and state)
Fig. 5, plug-type static micro-electromechanical system (MEMS) switch cross-section structure
Embodiment
The invention provides the overall plan of a kind of battery, battery set charge/discharge protective circuit as shown in Figure 1; it is characterized in that applying micro-electromechanical system (MEMS) (MEMS (micro electro mechanical system)) switch replaces the MOSFET charge and discharge switch, battery, the battery set charge/discharge protective circuit of the present invention's design realize functional block diagram as shown in Figure 1.
The static micro-electromechanical system (MEMS) switch that connects two series connection at the negative pole end of battery pack, the negative pole end of battery pack connects the transmission line of first static micro-electromechanical system (MEMS) switch, first electrode of this first static micro-electromechanical system (MEMS) switch connects the transmission line of second static micro-electromechanical system (MEMS) switch, and first electrode of second static micro-electromechanical system (MEMS) switch is as the negative pole end output; Between the transmission line of each static micro-electromechanical system (MEMS) switch and first electrode and connect a diode, the positive pole of two diode utmost points links to each other; Positive terminal in battery pack connects sensitive resistance, the junction of each battery of the connection battery pack of the front-end detection circuit AFE of a simulation, and the front-end detection circuit AFE of simulation divides other to connect second electrode of two static micro-electromechanical system (MEMS) switch; The front-end detection circuit AFE of simulation connects microcontroller MCU; The sensitive resistance two ends connect microcontroller MCU.
The mode classification of current micro-electromechanical system (MEMS) switch has a variety of, and dividing with regard to contact type has two kinds of ohmic contact and capacitive coupling etc.With regard to ohmic contact type micro-electromechanical system (MEMS) switch, its microwave structure is based on a space on the co-planar waveguide, and the contact zone on the isolation beam moves and causes electrically contacting switch closure.Under the switch conduction state, its resistance is the contact resistance of two contact points, so its conducting resistance is far below MOSFET.Generally speaking, the conducting resistance of micro-electromechanical system (MEMS) switch is about 1/10 of a switch mosfet, therefore can significantly reduce the quiescent dissipation under the switch conduction state.
Micro-electromechanical system (MEMS) switch partly is made of mechanical part and electricity, and available static, magnetostatic, piezoelectricity or pyrogen reason provide actuating force for mechanical movement.The electricity part of switch can be arranged with series connection or parallel way, can be metal-metal contact or condenser type contact.Wherein static driven short, simple in structure because of it near zero dc power, switching time, easily process and be convenient to and integrated circuit (IC) chip (IC) process compatible obtains business circles and academia pays close attention to widely.Fundamental diagram when Fig. 3 is static driven micro-electromechanical system (MEMS) switch closed and disconnected.Wherein (a) expression is that switch disconnects, and is in open mode this moment.When adding driving voltage between top electrode and bottom electrode, the effect contact point that is subjected to electrostatic force contacts with transmission line, makes switch reach closure state shown in (b), this moment switch conduction.Wherein the electrostatic force that is produced under driving voltage V is:
In the formula: ε
0Be the dielectric constant of free space, A is the effective area of capacitor, and g is the interval between upper/lower electrode.The research of static driven micro-electromechanical system (MEMS) switch is the focus that business circles are pursued always, but the main cause that restricts its development is the driving voltage height, and membrane stress distortion and life-span lack and can not reach the requirement of industrial quarters.
Based on the basic problem in the static micro-electromechanical system (MEMS) switch of above elaboration; we have used a kind of plug-type micro-electromechanical system (MEMS) switch of static of based single crystal silicon beam as the charge and discharge protecting construction of switch; this structure can solve the defective that prior art exists preferably; reduce driving voltage, increased the life-span of switch significantly.Its basic thought is that the upper/lower electrode with the static micro-electromechanical system (MEMS) switch among Fig. 3 is designed to two pairs.When the signal of switch closure arrived, pair of electrodes wherein promoted cantilever beam, makes the contact zone contact with transmission line like this, and switch is realized conducting.Fig. 4 is the profile of this micro-electromechanical system (MEMS) switch structure.When the needs section was opened this micro-electromechanical system (MEMS) switch, this moment, control signal was added in another on the electrode, thereby the pulling cantilever beam makes the disconnection that is connected of contact zone and transmission line, the shutoff of realization switch.Concrete manufacturing process forms for make movable single crystal silicon beam (cantilever beam) by release groove, and in the two ends of beam sputter bottom electrode and contact zone, top electrode and transmission line form coplanar waveguide transmission line (CPW), guarantees that signal is not disturbed.Top electrode is fixed on the substrate by anchor point.
Claims (6)
1, a kind of battery pack protective circuit of applying micro-electromechanical system (MEMS) switch is characterized in that:
A microcontroller MCU, be used for the current anomaly of charge and discharge process is detected and controls, when situations such as charging or discharge process appearance overload or short circuit, this testing circuit can send one group and characterize the unusual interrupt signal of charge and discharge, this moment, the CPU of microcontroller then handled for the interrupt signal that testing circuit occurs, and showed present charging and discharging state;
An AFE (analog front end) testing circuit AFE is used to microprocessor power supply, and control charge and discharge micro-electromechanical system (MEMS) switch is realized charging and discharging function for battery pack, and voltage swing on the battery is surveyed;
A sensitive resistance is used for charging or discharging current are surveyed;
One or more charge and discharge micro-electromechanical system (MEMS) switch charges to battery, battery pack or discharges with lower quiescent dissipation.
2, the battery pack protective circuit of applying micro-electromechanical system (MEMS) switch according to claim 1 is characterized in that: carry out discharging and recharging of battery pack with one or more micro-electromechanical system (MEMS) switch.
3, the battery pack protective circuit of applying micro-electromechanical system (MEMS) switch according to claim 2 is characterized in that: use a plurality of micro-electromechanical system (MEMS) switch series connection or parallel connection and discharge and recharge.
4, the battery pack protective circuit of applying micro-electromechanical system (MEMS) switch according to claim 1 is characterized in that: with discrete device form, the some or all of battery that comprises micro-electromechanical system (MEMS) switch, the battery set charge/discharge protective circuit that realizes with the integrated circuit form.
5, the battery pack protective circuit of applying micro-electromechanical system (MEMS) switch according to claim 1, it is characterized in that: physical circuit is: the static micro-electromechanical system (MEMS) switch that connects two series connection at the negative pole end of battery pack, the negative pole end of battery pack connects the transmission line of first static micro-electromechanical system (MEMS) switch, first electrode of this first static micro-electromechanical system (MEMS) switch connects the transmission line of second static micro-electromechanical system (MEMS) switch, and first electrode of second static micro-electromechanical system (MEMS) switch is as the negative pole end output; Between the transmission line of each static micro-electromechanical system (MEMS) switch and first electrode and connect a diode, the positive pole of two diode utmost points links to each other; Positive terminal in battery pack connects sensitive resistance, the junction of each battery of the connection battery pack of the front-end detection circuit AFE of a simulation, and the front-end detection circuit AFE of simulation divides other to connect second electrode of two static micro-electromechanical system (MEMS) switch; The front-end detection circuit AFE of simulation connects microcontroller MCU; The sensitive resistance two ends connect microcontroller MCU.
6, a kind of battery pack protective circuit of applying micro-electromechanical system (MEMS) switch, this battery protecting circuit are applied to carry out battery protection in lithium battery, battery pack or other TunePowers, the battery pack.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA2008100528360A CN101567554A (en) | 2008-04-22 | 2008-04-22 | Battery pack protective circuit applying micro-electromechanical system (MEMS) switch |
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| Application Number | Priority Date | Filing Date | Title |
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| CNA2008100528360A CN101567554A (en) | 2008-04-22 | 2008-04-22 | Battery pack protective circuit applying micro-electromechanical system (MEMS) switch |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102236163A (en) * | 2011-04-18 | 2011-11-09 | 上海丽恒光微电子科技有限公司 | Micro-electro mechanical system (MEMS) light valve based display device and forming method thereof |
| CN102279463A (en) * | 2011-04-18 | 2011-12-14 | 上海丽恒光微电子科技有限公司 | Display device provided with micro-electromechanical system (MEMS) light valve and forming method thereof |
| CN106458573A (en) * | 2014-04-14 | 2017-02-22 | 天工方案公司 | Mems devices having discharge circuits |
-
2008
- 2008-04-22 CN CNA2008100528360A patent/CN101567554A/en active Pending
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102236163A (en) * | 2011-04-18 | 2011-11-09 | 上海丽恒光微电子科技有限公司 | Micro-electro mechanical system (MEMS) light valve based display device and forming method thereof |
| CN102279463A (en) * | 2011-04-18 | 2011-12-14 | 上海丽恒光微电子科技有限公司 | Display device provided with micro-electromechanical system (MEMS) light valve and forming method thereof |
| CN102279463B (en) * | 2011-04-18 | 2013-10-23 | 上海丽恒光微电子科技有限公司 | Display device provided with micro-electromechanical system (MEMS) light valve and forming method thereof |
| US8854712B2 (en) | 2011-04-18 | 2014-10-07 | Lexvu Opto Microelectronics Technology (Shanghai) Ltd | Display device provided with MEMS light valve and forming method thereof |
| CN106458573A (en) * | 2014-04-14 | 2017-02-22 | 天工方案公司 | Mems devices having discharge circuits |
| CN106458573B (en) * | 2014-04-14 | 2019-08-30 | 天工方案公司 | Mems device with discharge circuit |
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Open date: 20091028 |