Accompanying the development that lithium battery uses, the importance of another technology also is highlighted even more come out, this is batteries management system (BMS) . BMS can be wrapped with lithium battery normally compositive together, as the centre of management and monitoring lithium battery, the condition of monitoring batteries, prevent batteries to appear pass to charge and pass the case such as discharge, ensure ground of batteries on the safe side works, prolong the service life of batteries as far as possible. Specific will tell, the main function of BMS includes:

Regard a typical power electron as the system, the nature in the development of BMS is little not of magnetic component prop up.

Although magnetic component looks ordinary, it is one of compositive essential factor with power electron main system however, they are formed by winding and magnetism core normally, assuming store can, the job such as energy changeover and electric segregation. Common magnetic element includes transformer and inductor two kinds big, former and main act wave of transformation, filter, store can part, latter is assuming signal of flowing power source, solve the task such as EMI noise.

Want to issue an outstanding BMS plan, the type selecting of magnetic component and application are little not homework.

Combine the representative application setting of BMS, for instance the car carries the BMS in dynamical cell group (if pursue 1) design requirement, we are OK and general painted the appearance of ideal and magnetic component in giving BMS to design:

Power inductor is manostat develop the main component in attacking, in DC-DC converter, every adjust the circuit of power source needs an inductor, wait for action in order to realize direct current source of memory energy, smooth-going, filter except circuit noise.

Specific in the design to BMS, the type selecting of power inductor and application are facing the challenge of tripartite face: Above all, it needs to be able to be satisfied more the requirement of high-power, support bigger electric current; Next, have the capacity that controls EMI even, contented car and the EMC that industry applies the Yan Ke in the environment design a requirement; Have again, also want on the appearance more compact, for limited space applied design provides bigger flexibility.

According to type selecting of afore-mentioned design requirement, inductor of power of big electricity of Bourns SRP series is a good choice undoubtedly. Baconian rise, of inductor of SRP series power ” outstanding place ” reflect in:

• Have unique magnetism screen structure, can realize low EMI radiate, because this need not use additional screen fish trap in circuit system, save space and cost.

• Used compressed lead structure, conduce to reduce DCR resistance, achieve taller efficiency.

• Use core of magnetism of metallic alloy powder, support big saturated electric current, special agree with application of big electric current, high power.

• In the meantime, compressed lead and pulverous magnetism core, also be helpful for achieving more compact appearance, save systematic space.

• Be based on high temperature to classification material is made, have more excellent temperature stability, support is as high as the working temperature of 150 ° C.

Altogether, inductor of SRP series power used advanced material and structure, can come true efficient and exceed low DC resistor, and compact and efficient enclose (component height limits comes from 1mm 7mm) , the design of screen type still optimized EMI character — this design that to BMS circuit of this kind of control and power circuit border, very necessary. Can say, inductor of SRP series power collect afore-mentioned a variety of advantages at a suit, when type selecting of BMS magnetic component, it is a makings that cannot miss.

In BMS design, the character that because its are outstanding,push-pull type keeps apart DC-DC converter — be like stabler input electric current, fewer input circuit noise, and in high power application efficient — became a kind of commonly used develop to attack structure. Want to realize push-pull type low pressure to keep apart the design of DC-DC converter, an affirmation of efficient and safe push-pull type transformer is little not.

Bourns accords with the transformer of HCT series power source of AEC-Q200 standard, be born for this application namely.

Graph 3: Transformer of HCT series power source (graph source: Bourns)

HCT series transformer has 3.3V the input limits to 5V, offer 3.3V to come the 15V, output that is as high as 350mA, can configure compare for all sorts of v/LIT all over the ground number. Transformer of this series power source uses ferrite annular magnetism core, have tall coupling coefficient and efficient.

What be worth to be carried particularly is, because used the design of method of distance climbing report of innovation, voltaic method length increased in be enclosed compactly, this kind of new-style power source transformer although the appearance is compact, crust height is only 6.5mm, can offer however enhance insulation, at least the clearance of 8mm / distance climbing report, and the compression of 5kVAC, the high pressure that can satisfy high standards keeps apart a requirement.

Graph 4: HCT series transformer uses the design of method of distance climbing report of innovation, the space climbing report that obtained 8mm (graph source: Bourns)

In short, HCT series high pressure keeps apart push-pull transformer to accord with the occupation standard such as AEC-Q200, IEC 60950-1, IEC 62368-1 and IEC 60664-1, the setting that keeps apart to power of small direct current and maximum pressure need in BMS offerred a kind of good solution.

From the point of the working principle of BMS, its need carries batteries condition, data and order wired interface and advocate accuse CPU to have communication, of these data and information alternant, it is the key that BMS realizes efficient, reliable closed-loop control. Unfortunate is, the tall voltage of lithium battery group, add applied environment (like system of electric car power) in the many electromagnetism interference of existence, can correspond to BMS data cause undesirable effect. To come true BMS and advocate accuse the reliable communication between CPU, can offer high-pressured segregation and transformer of signal of EMI low-key BMS to come on stage with respect to need.

The transformer of SM91501AL BMS signal of Bourns is module of transformer of segregation of a double passageway, support serial chrysanthemum chain / IsoSPI, have 1600VDC job voltage, 4300VDC segregation voltage and – 40 ° C comes + the limits of patulous job temperature of 125 ° C. This signal transformer is compositive use at noise low-key in all modular choke, can realize the integrality of much better signal.

SM91501AL accords with AEC-Q200 standard and RoHS instruction, in and had applied in the reference of much money BMS of Analog Devices and NXP be being designed, passed the test and verify that applies actually, conduce to economic development time and reduce design risk considerably.

In the future that can foreknow, BMS market will accompany the development that lithium battery uses, enter a swift ascendant passage, this also brings new business chance for yuan of relevant parts of an apparatus. To the indispensable magnetic component in power electron system, more such.

Of course, can build on the magnetic component product of BMS market express, need satisfies a series of special design requirements, the respect waits in design of character of efficiency, hot property, EMI, miniaturization, dependability and security, must discrepant the prominent dominant position at current product.

Bourns is relied on tens of year major is accumulated, can offer complete magnetic component product to combine for BMS design. Pass the introduction of the article, you should can experience: Want to give out efficient, safe, reliable, provide competitive BMS product, single out the stock that you admire in the heart from which, was opposite!

Article origin: Trade lustre electron