AT513229B1 - Device for balancing series-connected batteries and capacitors - Google Patents

Abstract

The balancing of series connected batteries and capacitors is very important to prevent the destruction of cells or elements. 1 shows three series-connected batteries (UB1, UB2, UB3). At the middle (UB2) at the positive and the negative terminal one coil (L1, L2) are connected. Furthermore, the circuit consists of three active switches (T1, T2, T3) and two passive switches (D1H, D2H) whose cathodes are connected to the positive pole and two passive switches (D1L, D2L) whose anodes are connected to the negative pole. If current bidirectional active switches are used, the diodes may be omitted. Furthermore, each of the coils (L1, L2) can each be provided by a further winding for measurement purposes. The coils (L1, L2) may also be magnetically coupled together. Furthermore, there is the possibility that the coils (L1, L2) are divided into two magnetically well-coupled partial coils (LiA, LiB).

Description

description

DEVICE FOR THE SYMMETRY OF SERIES BATTERIES AND CAPACITORS The invention relates to a device for symmetrizing n series batteries (U _B i, - ÜBn) or n series capacitors (Ci, ... C _n ) , consisting of n -1 coils (L ^ .- Ln-i), n series-connected active switches (Τ ^.,. Τη) with associated control device, the negative connection of the first battery (U _B1 ) or the first capacitor (Ci) is connected to the negative connection of the first active switch (T), the positive connection of the nth battery (U _Bn ) or the positive connection of the nth capacitor (C _n2 ) to the positive connection of the nth active switch (T _n ) is connected to the connection point between two adjacent batteries (U _Bi ) (U _{Bi +} i) or two adjacent capacitors (C,) (C _{i +} i) (i between 1 and n-1) a coil (L) is connected, the second connection to the connection point between two adjacent active switches (T, (T _{i + 1} ) is connected, or a device for symmetrizing n series batteries (U _B i, ... U _Bn ) or n series capacitors (Ci, .. .C _n ), consisting of n-1 coils (L ^ .- Ln.-,), n-2 active switches connected in series (Τ ^ - .. TnJ with associated control device, a first group of n-2 diodes ( D _1L , ... D _n . _2L ), a second group of n-2 diodes (D _1H , ... D _n - _2H ), each at the connection point between two neighboring batteries (U _Bi ) (U _{Bi + 1} ) (i between 1 and n- 1) or two adjacent capacitors (Ci, ... C _{i + 1} ) (i between 1 and n- 1) a connection of a coil (L,) is connected, between the second connections of which an active switch (T,) ( i is switched between 1 and n-2).

The symmetry of series-connected batteries and capacitors is very important so that there is no destruction of cells or elements. There is a rich literature on this subject. The article "Passive and Active Battery Balancing Comparision based on MATLAB Simulations" by M. Daowd, N. Omar, P. van den Bossche, J. van Mierlo in the proceedings of the Vehicular Power and Propulsion Conference VPPC 2011 gives a good overview. A very frequently presented method can be found in the following patent source.

US 6121751 shows a device with switched capacitors. The device pumps charge from one cell to another. Charge is taken from the most charged cell and loaded into a neighboring cell. The difficulty with this system is the inherent loss of such energy transfer. As can be calculated, if a battery with the voltage U _{1 =} U ₂ + AU is transformed into a cell with the voltage U ₂ with such a device, the efficiency results

¹ 1 + U ₂ It can be seen: the smaller the voltage difference, the better the efficiency and vice versa. It is particularly important that the efficiency cannot be improved in principle, even if you use the best components. Therefore, a concept that carries out the energy transfer via the magnetic field is preferable. There would be no losses with ideal components.

In the following, a limitation and delimitation from the patent literature and the documents is made.

DE 102009015388 A1 (OSRAM GMBH) shows devices for energy balance between at least two cells which are connected in series. A separate converter is responsible for two cells. In the case of two cells, the concept corresponds to the present invention; in the case of more than two cells connected in series, it differs by the use of half-bridge Cuk converters. But you can omit the capacitors necessary for the Cuk converter, then the device still differs from the / 8

AT513 229 B1 2018-02-15 Austrian patent office invention through the different position of the coils. The modifications with various additional diodes for the defined energy control are not affected by DE 102009015388 A1.

CN 1489236 A (BEIJING JIAOTONG UNOV) meets the old claim 1, but not the other designs with various additional diodes for defined energy control.

US 5479083 A (BRAINARD GERALD L) comes from the structure very close to the old claim 1, but is more flexible due to the additional use of active switches and of course again more expensive. The designs with various additional diodes for the defined energy control in the present invention are not made thereby.

CN 101867210 A (UNIV ZHEJIANG SCIENCE & TECH) differs in the topology. The position of the components relative to one another is different.

US5631534A (LEWIS DAVE) represents a very complex device. The cells are coupled by bidirectional step-down converters. This enables energy to be exchanged directly between two neighboring cells and, by repeatedly pushing the charge, also between more distant ones. The efficiency then naturally decreases in accordance with the number of transformation steps.

DE 102010001423 A1 (SB LIMOTIVE CO LTD, SB LIMOTIVE GERMANY GMBH) meets the old claim 1 at least for two cells, but the more complex arrangement differs and requires a large additional number of controllable switches and is therefore very expensive. However, the further designs with various additional diodes for the defined energy control in the present invention are not made.

CN 201821125 U (YANTAI DONGFANG YOKELIN ELECTRONIC CO LTD) represents a balun circuit with a different arrangement of the components, that is, a different topology.

L. Wang et al.: "Based on Energy Transferring for Battery Packs Applied on Electric Vehicles", International Conference on Computer and Communication Technology in Agricultural Engineering, vol. 1,2010, pp. 271-274 rounds off the general state of the art.

The figures show forms of the present invention.

Fig. 1 and Fig. 2 show the balancing circuit for three and five stages for batteries.

3 and 4 show configurations for the balancing of capacitors.

Fig. 5 still shows that it is possible to run the coils as coupled coils with a common connection (tapping).

The present invention will now be explained with reference to the drawings.

Fig. 1 shows three batteries connected in series (U _B i, Ub2, U _B3 ). A coil (L _1; L ₂ ) is connected to the middle (U _B2 ) on the positive and the negative terminal. Furthermore, the circuit consists of three active switches (T _1; T ₂ , T ₃ ) and two passive switches (D _1H , D _2H ), the cathodes of which are connected to the positive pole and two passive switches (D _1L , D _2L ), the Anodes are connected to the negative pole. To extract excess energy from U _B3 , T _{3 is} switched on. This takes energy from U _B3 and stores it in coil L ₂ . T is turned off _3, then the current through U _B2 and U _B1 and D _2L runs freely. This transfers the energy to the two lower batteries. When the current has become zero, the diode turns off. (A second possibility to end the freewheeling would be to switch on T _{3 again} , which would result in a continuous current flow in L _2. ) If you want to transfer excess energy from U _B2 , T ₂ must be switched on. Caused by the current flow, magnetic energy builds up in the coils Lj and L ₂ . If T _{2 is} switched off, the stored energies are transferred to the batteries U _B3 and U _B1 . Due to the intermediate step via the magnetic field, this happens without principle-related losses. The losses that occur are only caused by the non-ideal components.

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AT513 229 B1 2018-02-15 Austrian Patent Office The circuit discussed is also suitable for symmetrizing capacitors instead of batteries. To do this, a series connection of capacitors must be arranged instead of the series connection of the batteries.

If one uses MOSFETs as active switches or generally current-bidirectional switches, the diodes can be omitted. Otherwise any type of active switch is suitable (current bidirectional, current unidirectional, voltage bidirectional, voltage unidirectional). If you want to implement the variant with the diodes with current-bidirectional switches (e.g. MOSFETs), it makes sense to connect one diode each in series with the bidirectional switches. This makes the bidirectional switch unidirectional.

[0022] In general, the device can be regarded as a charge pump system. The easiest way to charge charge is to completely demagnetize the coils. You then only need control pulses of a fixed duration. During this time the coil magnetizes / the coils magnetize. After switching off, demagnetization takes place. This time is easy to calculate and can easily be determined for the worst case. This allows the repetition rate to be set. Of course, you can also determine the switch-off time using the maximum current that occurs. However, this requires additional current detection and a comparator. The reclosing time can also be triggered by detecting the zero current crossing in the coil. The zero current crossing can be easily detected by a winding magnetically coupled to the coil. This coil also enables the potential-free detection of the voltage on the coils for measuring and control purposes. However, the least effort is certainly to take charge from the battery or capacitor, which has the greatest voltage, for a fixed constant time and this at a repetition rate at which it is ensured that the coil or the coils has demagnetized /to have.

Figure 2 shows the expansion of the circuit of FIG. 1 to n series batteries.

The balancing of capacitors is particularly important at higher voltages. There you will also use IGBTs or something similar. For this reason, examples are drawn. The structure in Fig. 4 is the same as in Fig. 2. Fig. 3 differs in that the top and bottom active switches are omitted. However, this simplification has the disadvantage that the top and the bottom capacitor cannot be actively balanced.

Under certain circumstances, it may be useful not to take individual coils as energy stores, but also to couple the coils to one another.

Another extension of the invention is the possibility of not using individual coils, but rather two coils coupled to one another as magnetic energy stores. There are two ways of doing this, as shown in FIG. 5.

If sufficient voltage is available on the batteries or capacitors, the system can also be made self-sufficient, since this voltage is available for the control circuit of the active switch. The control then takes place as described above and is released by a window comparator. If the voltage exceeds a certain value, a charge is transferred until a lower threshold is reached. This control method is particularly suitable if only a few stages or not all active switches are equipped.

This autonomous control can also be operated in such a way that it is released by a higher-level control unit. The clocking can be enabled via optocouplers or similar. respectively. The higher-level control system has the voltage values at the batteries or capacities available. The release then takes place e.g. so that the greatest partial tension is reduced and only if the symmetry shifts too much.

Furthermore, it should be noted that the number of active switches or diodes at the expense of

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AT513 229 B1 2018-02-15 Austrian

Patent office full controllability can be reduced. This is useful if certain asymmetries can be expected from the inside, caused by the construction or operation.

The task of symmetrizing batteries or capacitors takes place according to the invention in that the negative connection of the first battery (U _B1 ) or the first capacitor (Ci) with the anodes of the first group of n-1 diodes (D _1L , ... D _n . _1L ), the positive connection of the nth battery (U _Bn ) is connected to the cathodes of the second group of n-1 diodes (D _1H , ... D _n _ _1H ), to the negative connection the further active switches (T ₂ , ... T _n ) each have a cathode of the first group of n-1 diodes (D _1L , ... D _n . _1L ) and to each positive connection of the further active switches (14,. ..T _n . ₂ ) one anode of the second group of n-1 diodes (D _1H , ... D _n _ _1H ) is connected, or that the negative connection of the first battery (U _B i) or the first capacitor (C ^ is connected to the anodes of the first group of n-2 diodes (D _1L , ... D _n . _2L ), the positive connection of the nth battery (U _Bn ) or the nth capacitor to the cathodes the second n group of n-1 diodes (D _1H , ... D _n _ _1H ) is connected to the negative connection of the active switches (Ti, ... T _n - ₂ ) each a cathode of the first group of n-2 Diodes (D _1L , ... D _n . _2L ) and an anode of the second group of n-2 diodes (D _1H , ... D _n . _2H ) is connected to each positive connection of the active switches (14, ... 14.2).

Furthermore, each of the coils (L ^ .- Ln-i) can each be provided with a further winding for measurement purposes.

The coils (L ^ .- Ln-i) can be magnetically coupled to one another.

There is also the possibility that the coils (L ^ -. Ln-i) are each divided into two sub-coils (L _iA , L _iB ) that are well magnetically coupled to one another and to the connection point of the partial windings (L _iA , L _iB ) the positive connection of the i-th active switch (T,) and to the second connection of the second partial winding (L _iB ) the negative connection of the i + 1-th active switch (T _{i + 1} ) is connected, or that the coils ( L ^ -. Ln-i) are each divided into two magnetically well-coupled sub-coils (L _iA , L _iB ) and at the connection point of the sub-windings (L _iA , L _iB ) the negative connection of the i + 1-th active switch ( T _{i + 1} ) and the positive connection of the i-th active switch (T,) is connected to the second connection of the second partial winding (L _iB ).

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Claims (6)

claims 1. Device for symmetrizing n series batteries (U _B i, ... U _B i) or n series capacitors (Cn-.Cn), consisting of n-1 coils (! _!, .. L _n -i), n series-connected active switches (Τ ^.,. Τη) with associated control device, the negative connection of the first battery (U _B i) or the first capacitor (Ci) with the negative connection of the first active switch (T) is connected, the positive connection of the nth battery (U _Bn ) or the positive connection of the nth capacitor (C _n2 ) is connected to the positive connection of the nth active switch (T _n ), respectively the connection point between two adjacent batteries (U _Bi ) (U _{Bi +} i) or two adjacent capacitors (C,) (C _{i + 1} ) (i between 1 and n-1) a connection of a coil (L,) is connected, the second connection to the connection point between two adjacent active switches (T,), (T _{i + 1} ), characterized in that the negative e Connection of the first battery (U _B1 ) or the first capacitor (C ^ is connected to the anodes of the first group of n-1 diodes (D _1L , ... D _n _ _1L ), the positive connection of the nth battery (U _Bn ) with the cathodes of the second group of n-1 diodes (D _1H , ... D _n . _1H ) is connected to the negative connection of the further active switches (T ₂ , ... T _n ) one cathode each of the first group of n-1 diodes (D _1L , ... D _n _ _1L ) and to each positive Connection of the other active switches (Τ ^.,. Τη ^) one anode each of the second group of n-1 diodes (D _1H , ... D _n _ ih) is connected. 2. Device for symmetrizing n series batteries (U _B i, ... U _Bn ) or n series capacitors (Ci, ... C _n ), consisting of n-1 coils (L ^ .Ln- i), n-2 active switches connected in series (Τη.,. Τ ^) with associated control device, a first group of n-2 diodes (D _1L , ... D _n . _2L ), a second group of n- 2 diodes (D _1H , ... D _n - _2H ), each at the connection point between two adjacent batteries (U _Bi ) (U _{Bi + 1} ) (i between 1 and n-1) or two adjacent capacitors (Ci, ... C _{i + 1} ) (i between 1 and n-1) a connection of a coil (L,) is connected, between the second connections of which an active switch (T,) (i between 1 and n-2) is connected is characterized in that the negative connection of the first battery (U _B i) or the first capacitor (C!) is connected to the anodes of the first group of n-2 diodes (D _1L , ... D _n _ _2L ) , the positive connection of the nth battery (U _Bn ) or the nth cond nsators _n with the cathodes of the second group of n-1 diode (D _{1 H,} ... D. _1H ) is connected to the negative connection of the active switches (Τ ^, .- Τη ^) one cathode of the first group of n-2 diodes (D _1L , ... D _n _ _2L ) and to each positive connection of the active switch (Τ ^, .- Τη ^) one anode of the second group of n-2 diodes (D _1H , ... D _n . _2H ) is connected. 3. Device according to one of claims 1 or 2, characterized in that the coils (L ^ .- Ln-i) are each provided by a further winding for measurement purposes. 4. Device according to one of claims 1 to 3, characterized in that the coils (L ^ .Ln-i) are magnetically coupled to one another. 5. Device according to one of claims 1 to 4, characterized in that the coils (U, .. L _n _i) are each divided into two magnetically well-coupled partial coils (L _iA , L _iB ) and at the connection point of the partial windings ( is L _iA, L _iB) of the positive terminal of the i-th active switch (T,) and to the second terminal of the second partial winding (L _iB), the negative terminal of the i + 1-th active switch (T _{i + 1)} connected , 6. A device as claimed in one of claims 1 to 5, that the coils (L ^ -. Ln-i) are divided into two magnetically with each other well coupled partial coils (L _iA, L _iB) and to the junction point of the partial windings (L _iA , L _iB ) the negative connection of the i + 1-th active switch (T _{i + 1} ) and to the second connection of the second partial winding (L _iB ) the positive connection of the i-th active switch (T,) is connected.