CN109245216A - The equalizing circuit and its control method of a kind of charged in parallel and the dual equalization discharge of two-way inverse-excitation type - Google Patents

Abstract

The invention discloses the equalizing circuits and its control method of a kind of charged in parallel and the dual equalization discharge of two-way inverse-excitation type, charged in parallel may be implemented in the present invention, the single battery is just isolated into charging circuit when any one single battery reaches the blanking voltage of setting, charge cutoff voltage of the final all single batteries all set by reach due to stops charging to reach the balanced purpose of pressure.Equalization discharge controls Mosfet switch by PWM to change circuit structure while carry out to SOC in the battery pack minimum highest single battery of single battery and SOC balanced using a series of two-way flyback transformer, this kind of equalization discharge method considers the equilibrium of highest SOC single battery and minimum SOC single battery simultaneously, balancing speed is accelerated, the inconsistency between each single battery can be effectively reduced.

Description

Equalizing circuit for parallel charging and bidirectional flyback double discharge equalization and control method thereof

Technical Field

The invention relates to an equalizing circuit for parallel charging and bidirectional flyback double discharge equalization and a control method thereof, belonging to the technical field of power electronic technology and storage battery energy equalization management.

Background

With the change of times and the rapid development of economy, the consumption of fossil energy is accelerated and the environmental deterioration is aggravated while automobiles become main vehicles. Electric vehicles gradually approach the public, and electric vehicles are bound to become the mainstream vehicles in the future due to the advantages of cleanness, environmental protection, low noise and the like, however, the most critical technology of electric vehicles is energy storage, and the storage capacity of electric energy directly restricts the development of the electric vehicle industry. With the rapid development of batteries and battery management technologies, lithium ion batteries have advantages of high energy density, relatively high nominal voltage, no memory effect, no pollution and the like, are favored by the market, and are widely applied to energy storage of electric vehicles.

In order to meet the requirements of driving the voltage and the current of the motor of the electric automobile, a large number of single lithium ion batteries are required to be connected in series for use. However, in the manufacturing process of the battery 1, the capacity, the internal resistance and the like of the battery in the same batch are different due to the process and the like; 2. the self-discharge rate of the batteries is different, and the long-time accumulation causes the difference of the battery capacity; 3. during the use of the battery, the use environment (temperature, difference of circuit boards, etc.) causes the difference of the battery capacity. And the like, can cause inconsistencies between the individual cells in the battery pack.

The capacity of the battery pack connected in series is affected by the capacity of the minimum single battery, and imbalance among the single batteries not only reduces the stored electric quantity but also shortens the service life of the battery pack, so that energy balance management needs to be performed on the battery pack to improve the discharge capacity and the service life of the battery.

Disclosure of Invention

The invention provides a balancing circuit for parallel charging and bidirectional flyback double discharge balancing and a control method thereof, aiming at the problem of inconsistent energy among a large number of lithium ion single batteries connected in series in a vehicle-mounted lithium ion power battery system of an electric vehicle.

The technical scheme of the invention is as follows: an equalizing circuit for parallel charging and bidirectional flyback dual discharge equalization is composed of battery pack, relay and NC_jBidirectional flyback transformer and Mosfet switch M_aMosfet switch N_bHigh reverse voltage schottky diode G_a1High reverse voltage schottky diode G_b2Forming;

the battery pack consists of n single batteries C_iThe component is that a normally closed relay NC is connected in series between every two adjacent single batteries_jThe bidirectional flyback transformer is composed of a primary coil T of a transformer_i1Secondary winding T of transformer_i2Mosfet switch Q_i1Mosfet switch Q_i2High reverse voltage schottky diode D_i1High reverse voltage schottky diode D_i2Forming;

the primary coil T of the transformer_e1One end of which is connected with the single battery C_ePositive electrode of (2), primary coil of transformer (T)_e1Another end of the switch Q is connected with a Mosfet switch_e1Drain, high reverse voltage schottky diode D_e1The cathode of (a) is provided,mosfet switch Q_e1Source and high reverse voltage schottky diode D_e1Anode of (2) is connected with the single battery C_eOn the negative electrode; transformer secondary coil T_e2One end of which is connected with the single battery C₁Positive electrode of (2), Mosfet switch M_eDrain electrode of (1), secondary winding of transformer (T)_e2Another end of the switch Q is connected with a Mosfet switch_e2Drain, high reverse voltage schottky diode D_e2Cathode of (2), Mosfet switch M_eWith source connected to a high reverse voltage schottky diode G_e1Anode of (2), high reverse voltage schottky diode G_e1Is connected with the single battery C_eOn the positive pole of (2), Mosfet switch Q_e2Source and high reverse voltage schottky diode D_e2Anode of (2) a common diode G_e2Cathode and single cell C_nNegative electrode of (1), high reverse voltage schottky diode G_e2Anode of (2) is connected to the Mosfet switch N_eOn the source of (1), Mosfet switch N_eIs connected with the single battery C_eOn the negative electrode;

the primary coil T of the transformer₁₁One end of which is connected with the single battery C₁Positive electrode of (2), primary coil of transformer (T)₁₁Another end of the switch Q is connected with a Mosfet switch₁₁Drain, high reverse voltage schottky diode D₁₁Cathode of (2), Mosfet switch Q₁₁Source and high reverse voltage schottky diode D₁₁Anode of (2) is connected with the single battery C₁On the negative electrode; transformer secondary coil T₁₂One end of which is connected with the single battery C₁Positive pole of (2), secondary winding of transformer (T)₁₂Another end of the switch Q is connected with a Mosfet switch₁₂Drain, high reverse voltage schottky diode D₁₂Cathode of (2), Mosfet switch Q₁₂Source and high reverse voltage schottky diode D₁₂Are commonly connected to a diode G₁₂Cathode and single cell C_nNegative electrode of (1), high reverse voltage schottky diode G₁₂Anode of (2) is connected to the Mosfet switch N₁On the source of (1), Mosfet switch N₁Is connected with the single battery C₁On the negative electrode;

the transformer primary wireRing T_n1One end of which is connected with the single battery C_nPositive electrode of (2), primary coil of transformer (T)_n1Another end of the switch Q is connected with a Mosfet switch_n1Drain, high reverse voltage schottky diode D_n1Cathode of (2), Mosfet switch Q_n1Source and high reverse voltage schottky diode D_n1Anode of (2) is connected with the single battery C_nOn the negative electrode; transformer secondary coil T_n2One end of which is connected with the single battery C₁Positive electrode of (2), Mosfet switch M_nDrain electrode of (1), secondary winding of transformer (T)_n2Another end of the switch Q is connected with a Mosfet switch_n2Drain, high reverse voltage schottky diode D_n2Cathode of (2), Mosfet switch M_nWith source connected to a high reverse voltage schottky diode G_n1Anode of (2), high reverse voltage schottky diode G_n1Is connected with the single battery C_nOn the positive pole of (2), Mosfet switch Q_n2Source and high reverse voltage schottky diode D_n2Anode of (2) is connected with the single battery C_nOn the negative electrode;

wherein i =1,2,3,. n, j =1,2,3,. n-1, a =2,3,4,. n, b =1,2,3,. n-1, e =2,3,. n-1.

The relay is G8N-1L-DC 12.

When the equalizing circuit performs charge equalization, if a certain single battery reaches a set charge cut-off voltage, the Mosfet switch corresponding to the single battery is controlled to be switched off, so that the single battery is isolated from the charging circuit until all the single batteries finally reach the charge cut-off voltage, and at the moment, all the single batteries are isolated from the charging circuit, and the charging circuit is in a disconnected state; finally, all the single batteries stop charging due to the fact that the set charging cut-off voltage is reached, and the purpose of forced equalization is achieved; and a single battery C_eThe corresponding Mosfet switch is a Mosfet switch M_eAnd Mosfet switch N_eAnd a single cell C₁The corresponding Mosfet switch is a Mosfet switch N₁And a single cell C_nThe corresponding Mosfet switch is a Mosfet switch M_n。

The equalizing circuit furtherWhen the line discharge is balanced, if a certain single battery C exists_xIs the highest SOC single battery in the battery pack and the voltage V thereof_xAnd average voltage V of battery pack_av△ V of the difference₁When not less than α, PWM is adopted to match the single battery C_xCorresponding Mosfet switch Q_x1Performing high-frequency on-off control: when Q is_x1In the on state, the current flows from the single battery C_xThe positive electrode of the transformer flows out and passes through a primary coil T of the transformer_x1Mosfet switch Q_x1Back to the single cell C_xThe negative electrode of (1); when Q is_x1In the off state, the secondary winding T of the transformer is at the moment_x2Inducing corresponding electromotive force current from secondary coil T of transformer_x2One end flows out and returns to the secondary coil T of the transformer through the load_x2The other end, so that the energy in the single battery with the highest SOC is transferred to the battery pack;

if there is a certain single battery C_yIs the lowest SOC single battery of the battery pack and the voltage V thereof_yAnd average voltage V of battery pack_av△ V of the difference₂When not more than β, PWM is adopted to match the single battery C_yCorresponding Mosfet switch Q_y2Performing high-frequency on-off control: when Q is_y2In the on state, the current flows from the single battery C₁The positive pole of the transformer flows out and passes through a secondary coil T of the transformer_y2Mosfet switch Q_y2Back to the single cell C_nThe negative electrode of (1); when Q is_y2In the off state, the primary winding T of the transformer is at the moment_y1Inducing a corresponding electromotive current from the primary winding T of the transformer_y1One end flows out and returns to the primary coil T of the transformer through the load_y1The other end, so that the energy in the battery pack is transferred to the lowest SOC single battery;

wherein,，x,y∈[1,n]，△V₁=V_x—V_av，△V₂=V_y—V_avthe positive numbers α and β each indicate a threshold value.

A control method of an equalizing circuit for parallel charging and bidirectional flyback dual discharge equalization, the method comprises the following steps:

charging equalization: PWM control of all Mosfet switches M_aMosfet switch N_bAre all in a conducting state, and control all the Mosfet switches Q_i1Mosfet switch Q_i2All are in off state, and control the normally closed relay NC_jWhen the single batteries are in a disconnected state, all the single batteries are directly connected to a power supply in parallel, if a certain single battery reaches a set charging cut-off voltage, a Mosfet switch corresponding to the single battery is controlled to be disconnected, so that the single battery is isolated from a charging circuit until all the single batteries finally reach the charging cut-off voltage, and at the moment, all the single batteries are isolated from the charging circuit, and the charging circuit is in a disconnected state; finally, all the single batteries stop charging due to the fact that the set charging cut-off voltage is reached, and the purpose of forced equalization is achieved; and a single battery C_eThe corresponding Mosfet switch is a Mosfet switch M_eAnd Mosfet switch N_eAnd a single cell C₁The corresponding Mosfet switch is a Mosfet switch N₁And a single cell C_nThe corresponding Mosfet switch is a Mosfet switch M_n；

Discharge equalization: PWM control of all Mosfet switches M_aMosfet switch N_bAll the Mosfet switches Q are in an off state and are controlled_i1Mosfet switch Q_i2All are in off state, and control the normally closed relay NC_jWhen the single batteries are in the connection state, all the single batteries are in the series connection state;

if there is a certain single battery C_xIs the highest SOC single battery in the battery pack and the voltage V thereof_xAnd average voltage V of battery pack_av△ V of the difference₁When not less than α, PWM is adopted to match the single battery C_xCorresponding Mosfet switch Q_x1Performing high-frequency on-off control: when Q is_x1In the on state, the current flows from the single battery C_xThe positive electrode of the transformer flows out and passes through a primary coil T of the transformer_x1Mosfet switch Q_x1Back to the single cell C_xThe negative electrode of (1); when Q is_x1In the off state, the secondary winding T of the transformer is at the moment_x2Inducing corresponding electromotive force current from secondary coil T of transformer_x2One end flows out and returns to the secondary coil T of the transformer through the load_x2The other end, so that the energy in the single battery with the highest SOC is transferred to the battery pack;

if there is a certain single battery C_yIs the lowest SOC single battery of the battery pack and the voltage V thereof_yAnd average voltage V of battery pack_av△ V of the difference₂When not more than β, PWM is adopted to match the single battery C_yCorresponding Mosfet switch Q_y2Performing high-frequency on-off control: when Q is_y2In the on state, the current flows from the single battery C₁The positive pole of the transformer flows out and passes through a secondary coil T of the transformer_y2Mosfet switch Q_y2Back to the single cell C_nThe negative electrode of (1); when Q is_y2In the off state, the primary winding T of the transformer is at the moment_y1Inducing a corresponding electromotive current from the primary winding T of the transformer_y1One end flows out and returns to the primary coil T of the transformer through the load_y1The other end, so that the energy in the battery pack is transferred to the lowest SOC single battery;

wherein,，x,y∈[1,n]，△V₁=V_x—V_av，△V₂=V_y—V_avthe positive numbers α and β each indicate a threshold value.

The invention has the beneficial effects that: the invention can realize parallel charging, when any single battery reaches the set cut-off voltage, the single battery is isolated from the charging circuit, and finally all the single batteries stop charging because of reaching the set charging cut-off voltage, thereby achieving the purpose of forced equalization. The discharging equalization method simultaneously considers the equalization of the highest SOC single battery and the lowest SOC single battery, accelerates the equalization rate and can effectively reduce the inconsistency among the single batteries. The charging speed can be obviously improved through the equalizing circuit, the consistency of each single battery is kept without an additional equalizing circuit during charging, and the highest SOC single battery and the lowest SOC single battery are equalized at the same time in discharging equalization to improve the equalizing speed. The equalization circuit is simple in principle, easy to control and high in equalization speed. The battery pack is formed by n single batteries, and the parity of n does not influence the battery pack structure, thereby facilitating the expansion of the circuit structure.

Drawings

FIG. 1 is a schematic diagram of the present invention;

fig. 2 is a schematic diagram of a charge equalization circuit for n cells;

fig. 3 is a schematic diagram of a discharge equalization circuit for n cells;

FIG. 4 is a schematic diagram of a charge equalization circuit for 4 cells;

FIG. 5 is a charging equalization equivalent circuit diagram for 4 cells;

FIG. 6 is a schematic diagram of a discharge equalization circuit for 4 cells;

FIG. 7 is a discharge equalization equivalent circuit diagram of 4 single cells;

wherein the gray portions are off and the black portions are on or active as shown in the figure (note that ①② in figure 7 represents the transfer of energy from ① to ②).

Detailed Description

Example 1: as shown in figure 1, an equalizing circuit for parallel charging and bidirectional flyback double discharge equalization comprises a battery pack and a relay NC_jBidirectional flyback transformer and Mosfet switch M_aMosfet switch N_bHigh reverse voltage schottky diode G_a1High reverse voltage schottky diode G_b2Forming;

the battery pack consists of n single batteries C_iThe component is that a normally closed relay NC is connected in series between every two adjacent single batteries_jThe bidirectional flyback transformer is composed of a primary coil T of a transformer_i1Secondary winding T of transformer_i2Mosfet switch Q_i1Mosfet switch Q_i2High reverse voltage schottky diode D_i1High reverse voltage schottky diode D_i2Forming;

the primary coil T of the transformer_e1One end of which is connected with the single battery C_ePositive electrode of (2), primary coil of transformer (T)_e1Another end of the switch Q is connected with a Mosfet switch_e1Drain, high reverse voltage schottky diode D_e1Cathode of (2), Mosfet switch Q_e1Source and high reverse voltage schottky diode D_e1Anode of (2) is connected with the single battery C_eOn the negative electrode; transformer secondary coil T_e2One end of which is connected with the single battery C₁Positive electrode of (2), Mosfet switch M_eDrain electrode of (1), secondary winding of transformer (T)_e2Another end of the switch Q is connected with a Mosfet switch_e2Drain, high reverse voltage schottky diode D_e2Cathode of (2), Mosfet switch M_eWith source connected to a high reverse voltage schottky diode G_e1Anode of (2), high reverse voltage schottky diode G_e1Is connected with the single battery C_eOn the positive pole of (2), Mosfet switch Q_e2Source and high reverse voltage schottky diode D_e2Anode of (2) a common diode G_e2Cathode and single cell C_nNegative electrode of (1), high reverse voltage schottky diode G_e2Anode of (2) is connected to the Mosfet switch N_eOn the source of (1), Mosfet switch N_eIs connected with the single battery C_eOn the negative electrode;

the primary coil T of the transformer₁₁One end of which is connected with the single battery C₁Positive electrode of (2), primary coil of transformer (T)₁₁Another end of the switch Q is connected with a Mosfet switch₁₁Drain, high reverse voltage schottky diode D₁₁Cathode of (2), Mosfet switch Q₁₁Source and high reverse voltage schottky diode D₁₁Anode of (2) is connected with the single battery C₁On the negative electrode; transformer secondary coil T₁₂One end of which is connected with the single battery C₁Positive pole of (2), secondary winding of transformer (T)₁₂Another end of the switch Q is connected with a Mosfet switch₁₂Drain, high reverse voltage schottky diode D₁₂Cathode of (2), Mosfet switch Q₁₂Source and high reverse voltage schottky diode D₁₂Are commonly connected to a diode G₁₂Cathode and single cell C_nNegative electrode of (1), high reverse voltage schottky diode G₁₂Anode of (2) is connected to the Mosfet switch N₁On the source of (1), Mosfet switch N₁Is connected with the single battery C₁On the negative electrode;

the primary coil T of the transformer_n1One end of which is connected with the single battery C_nPositive electrode of (2), primary coil of transformer (T)_n1Another end of the switch Q is connected with a Mosfet switch_n1Drain, high reverse voltage schottky diode D_n1Cathode of (2), Mosfet switch Q_n1Source and high reverse voltage schottky diode D_n1Anode of (2) is connected with the single battery C_nOn the negative electrode; transformer secondary coil T_n2One end of which is connected with the single battery C₁Positive electrode of (2), Mosfet switch M_nDrain electrode of (1), secondary winding of transformer (T)_n2Another end of the switch Q is connected with a Mosfet switch_n2Drain, high reverse voltage schottky diode D_n2Cathode of (2), Mosfet switch M_nWith source connected to a high reverse voltage schottky diode G_n1Anode of (2), high reverse voltage schottky diode G_n1Is connected with the single battery C_nOn the positive pole of (2), Mosfet switch Q_n2Source and high reverse voltage schottky diodeD_n2Anode of (2) is connected with the single battery C_nOn the negative electrode;

wherein i =1,2,3,. n, j =1,2,3,. n-1, a =2,3,4,. n, b =1,2,3,. n-1, e =2,3,. n-1.

Further, the relay model number can be set to G8N-1L-DC 12.

Further, the high reverse voltage schottky diode may be configured to employ SR 2200.

Further, when the equalizing circuit is set to perform charge equalization, if a certain single battery reaches a set charge cut-off voltage, the Mosfet switch corresponding to the single battery is controlled to be turned off, so that the single battery is isolated from the charging circuit until all the single batteries finally reach the charge cut-off voltage, and at this time, all the single batteries are isolated from the charging circuit, and the charging circuit is in a disconnected state; finally, all the single batteries stop charging due to the fact that the set charging cut-off voltage is reached, and the purpose of forced equalization is achieved; and a single battery C_eThe corresponding Mosfet switch is a Mosfet switch M_eAnd Mosfet switch N_eAnd a single cell C₁The corresponding Mosfet switch is a Mosfet switch N₁And a single cell C_nThe corresponding Mosfet switch is a Mosfet switch M_n。

Further, the equalizing circuit may be configured to perform discharge equalization when there is a certain single battery C_xIs the highest SOC single battery in the battery pack and the voltage V thereof_xAnd average voltage V of battery pack_av△ V of the difference₁When not less than α, PWM is adopted to match the single battery C_xCorresponding Mosfet switch Q_x1Performing high-frequency on-off control: when Q is_x1In the on state, the current flows from the single battery C_xThe positive electrode of the transformer flows out and passes through a primary coil T of the transformer_x1Mosfet switch Q_x1Back to the single cell C_xThe negative electrode of (1); when Q is_x1In the off state, the secondary winding T of the transformer is at the moment_x2Inducing corresponding electromotive force current from secondary coil T of transformer_x2Flows out of one endReturns to the secondary winding T of the transformer through the load_x2The other end, so that the energy in the single battery with the highest SOC is transferred to the battery pack; if there is a certain single battery C_yIs the lowest SOC single battery of the battery pack and the voltage V thereof_yAnd average voltage V of battery pack_av△ V of the difference₂When not more than β, PWM is adopted to match the single battery C_yCorresponding Mosfet switch Q_y2Performing high-frequency on-off control: when Q is_y2In the on state, the current flows from the single battery C₁The positive pole of the transformer flows out and passes through a secondary coil T of the transformer_y2Mosfet switch Q_y2Back to the single cell C_nThe negative electrode of (1); when Q is_y2In the off state, the primary winding T of the transformer is at the moment_y1Inducing a corresponding electromotive current from the primary winding T of the transformer_y1One end flows out and returns to the primary coil T of the transformer through the load_y1The other end, so that the energy in the battery pack is transferred to the lowest SOC single battery;

wherein,，x,y∈[1,n]，△V₁=V_x—V_av，△V₂=V_y—V_avthe positive numbers α and β each indicate a threshold value.

A control method of an equalizing circuit for parallel charging and bidirectional flyback dual discharge equalization, the method comprises the following steps:

charging equalization: during the charging process of the battery pack (as shown in fig. 2), PWM is adopted to control all the Mosfet switches M_aMosfet switch N_bAre all in a conducting state, and control all the Mosfet switches Q_i1Mosfet switch Q_i2All are in off state, and control the normally closed relay NC_jAll the single batteries are directly connected in parallel to the power supply in the disconnected state, and if a certain single battery reaches the set charging cut-off voltage, the Mosfet switch corresponding to the single battery is controlled to be disconnected, so that the single battery is isolated from the charging circuit until all the single batteries finally reach the set charging cut-off voltageWhen the charging cut-off voltage is reached, all the single batteries are isolated from the charging circuit, and the charging circuit is in a disconnected state; finally, all the single batteries stop charging due to the fact that the set charging cut-off voltage is reached, and the purpose of forced equalization is achieved; and a single battery C_eThe corresponding Mosfet switch is a Mosfet switch M_eAnd Mosfet switch N_eAnd a single cell C₁The corresponding Mosfet switch is a Mosfet switch N₁And a single cell C_nThe corresponding Mosfet switch is a Mosfet switch M_n；

Discharge equalization: during the discharging process of the battery pack (as shown in fig. 3), PWM is adopted to control all the Mosfet switches M_aMosfet switch N_bAll the Mosfet switches Q are in an off state and are controlled_i1Mosfet switch Q_i2All are in off state, and control the normally closed relay NC_jWhen the single batteries are in the connection state, all the single batteries are in the series connection state;

if there is a certain single battery C_xIs the highest SOC single battery in the battery pack and the voltage V thereof_xAnd average voltage V of battery pack_av△ V of the difference₁When not less than α, PWM is adopted to match the single battery C_xCorresponding Mosfet switch Q_x1Performing high frequency on-off control (Q)_i2（i=1,2,3,...n）、Q_i1（i=1,2,3,...n&i ≠ x) is in the off state): when Q is_x1In the on state, the current flows from the single battery C_xThe positive electrode of the transformer flows out and passes through a primary coil T of the transformer_x1Mosfet switch Q_x1Back to the single cell C_xThe negative electrode of (1); when Q is_x1In the off state, the secondary winding T of the transformer is at the moment_x2Inducing corresponding electromotive force current from secondary coil T of transformer_x2One end flows out and returns to the secondary coil T of the transformer through the load_x2The other end, so that the energy in the single battery with the highest SOC is transferred to the battery pack;

if there is a certain single battery C_yIs the lowest SOC single battery of the battery pack and the voltage V thereof_yAnd average voltage V of battery pack_av△ V of the difference₂When the voltage is less than or equal to β, PWM is adopted to carry out the comparison withThe single battery C_yCorresponding Mosfet switch Q_y2Performing high frequency on-off control (Q)_i2（i=1,2,3,...n&i≠y）、Q_i1(i =1,2, 3.. n) is off state): when Q is_y2In the on state, the current flows from the single battery C₁The positive pole of the transformer flows out and passes through a secondary coil T of the transformer_y2Mosfet switch Q_y2Back to the single cell C_nThe negative electrode of (1); when Q is_y2In the off state, the primary winding T of the transformer is at the moment_y1Inducing a corresponding electromotive current from the primary winding T of the transformer_y1One end flows out and returns to the primary coil T of the transformer through the load_y1The other end, so that the energy in the battery pack is transferred to the lowest SOC single battery;

if the two conditions are met, simultaneously controlling; if not, no treatment is carried out.

The discharging equalization scheme is characterized in that only the difference between the voltage of the highest SOC single battery and the average voltage is △ V₁When the SOC is not less than α, only the energy in the single battery is balanced into the battery pack, and when only the difference value between the voltage of the single battery with the lowest SOC and the average voltage is △ V₂When the SOC is less than or equal to β, only balancing the energy in the battery pack to the single battery, when the difference between the voltage of the single battery with the highest SOC and the average voltage is △ V₁Not less than α, difference value △ V between lowest SOC single battery voltage and average voltage₂And when the SOC is less than or equal to β, balancing the energy in the highest SOC single battery into the battery pack and balancing the energy in the battery pack into the lowest SOC single battery, thereby keeping the consistency of the single batteries.

Wherein,，x,y∈[1,n]，△V₁=V_x—V_av，△V₂=V_y—V_avthe positive numbers α and β each indicate a threshold value.

Example 2: take 4 cells as an example.

In the charging process (as shown in figures 4 and 5), PWM is adopted to control the Mosfet switch to be only conducted with M_a（a=2,3,4）、N_b(b =1,2, 3), controlling a normally closed relay NC_j(j =1,2, 3.. n-1) is turned on to be in an off state when all the unit cells are directly connected in parallel to the power supply, and the sequence of the unit cells reaching the charge cut-off voltage is assumed to be C₃、C₂、C₁、C₄。

(1) Control and single battery C₃Corresponding Mosfet switch M₃、N₃Is disconnected, thereby the single cell C is₃Isolating the charging circuit.

(2) Control and single battery C₂Corresponding Mosfet switch M₂、N₂Is disconnected, thereby the single cell C is₂Isolating the charging circuit.

(3) Control and single battery C₁Corresponding Mosfet switch N₁Is disconnected, thereby the single cell C is₃Isolating the charging circuit.

(4) Control and single battery C₄Corresponding Mosfet switch M₄Is disconnected, thereby the single cell C is₂Isolating the charging circuit.

And finally, all the single batteries reach the charging cut-off voltage, the charging circuit is isolated from all the single batteries at the moment, and the charging circuit is in a disconnected state. And finally, all the single batteries stop charging due to the fact that the set charging cut-off voltage is reached, so that the purpose of forced equalization is achieved.

In the discharging process (as shown in figures 6 and 7), the relay NC is normally closed_j(j =1,2, 3.. n-1) is in an on state when all the unit cells are in a series state. Hypothesis C₂Is the highest SOC single battery, C₃Is the lowest SOC single battery. ThenNamely the single battery C₂Voltage V of₂On average with the battery packVoltage V_avA difference of (d);namely the single battery C₃Voltage V of₃And average voltage V of battery pack_avThe difference of (a).

(1) If only △ V_maxWhen the voltage is more than or equal to α (positive number), PWM is adopted to match the single battery C₂Corresponding Mosfet switch Q₂₁Performing high frequency on-off control (Q)_i1（i=1,3,4,）、Q_i2(i =1,2,3, 4) is off), when Q is off₂₁In the on state, the current flows from the single battery C₂The positive electrode of the transformer flows out and passes through a primary coil T of the transformer₂₁(energy storing), Mosfet switch Q₂₁Back to the single cell C₂When Q is a negative electrode₂₁In the off state, the secondary winding T of the transformer is at the moment₂₂Inducing a corresponding electromotive current from the secondary winding T₂₂One end flows out and returns to the secondary coil T through the load₂₂The other end, so that the energy in the single battery with the highest SOC is transferred to the battery pack;

(2) if only △ V_minWhen the voltage is less than or equal to β (negative number), PWM is adopted to couple the single battery C₃Corresponding Mosfet switch Q₃₂Performing high frequency on-off control (Q)_i1（i=1,2,3,4）、Q_i2(i =1,2,4,) is off), when Q is off₃₂In the on state, the current flows from the single battery C₁The positive pole of the transformer flows out and passes through a secondary coil T of the transformer₃₂(energy storing), Mosfet switch Q₃₂Back to the single cell C_nWhen Q is a negative electrode₃₂In the off state, the primary winding T of the transformer is at the moment₃₁Inducing a corresponding electromotive current from the primary coil T₃₁One end flows out and returns to the primary coil T through the load₃₁And the other end, thereby transferring the energy in the battery pack to the lowest SOC cell.

(3) If △ V_maxNot less than α V (positive number) and △ V_minWhen the voltage is less than or equal to β (negative number), PWM is adopted to match the single battery C₂Corresponding Mosfet switchOff Q₂₁、C₃Corresponding Mosfet switch Q₃₂Performing high frequency on-off control (Q)_i1（i=1,3,4,）Q_i2(i =1,2, 4) in the off state), when Q is off₂₁In the on state, the current flows from the single battery C₂The positive electrode of the transformer flows out and passes through a primary coil T of the transformer₂₁(energy storing), Mosfet switch Q₂₁Back to the single cell C₂When Q is a negative electrode₂₁In the off state, the secondary winding T of the transformer is at the moment₂₂Inducing a corresponding electromotive current from the secondary winding T₂₂One end flows out and returns to the secondary coil T through the load₂₂The other end, so that the energy in the single battery with the highest SOC is transferred to the battery pack; when Q is₃₂In the on state, the current flows from the single battery C₁The positive pole of the transformer flows out and passes through a secondary coil T of the transformer₃₂(energy storing), Mosfet switch Q₃₂Back to the single cell C_nWhen Q is a negative electrode₃₂In the off state, the primary winding T of the transformer is at the moment₃₁Inducing a corresponding electromotive current from the primary coil T₃₁One end flows out and returns to the primary coil T through the single load₃₁And the other end, thereby transferring the energy in the battery pack to the lowest SOC cell.

While the present invention has been described in detail with reference to the embodiments shown in the drawings, the present invention is not limited to the embodiments, and various changes can be made without departing from the spirit of the present invention within the knowledge of those skilled in the art.

Claims (5)

1. An equalizing circuit for parallel charging and bidirectional flyback double discharge equalization is characterized in that: by battery, relay NC_jBidirectional flyback transformer and Mosfet switch M_aMosfet switch N_bHigh reverse voltage schottky diode G_a1High reverse voltage schottky diode G_b2Forming;

the battery pack consists of n single batteries C_iThe component is that a normally closed relay NC is connected in series between every two adjacent single batteries_jThe bidirectional flyback transformer is composed of a transformer sourceCoil T_i1Secondary winding T of transformer_i2Mosfet switch Q_i1Mosfet switch Q_i2High reverse voltage schottky diode D_i1High reverse voltage schottky diode D_i2Forming;

the primary coil T of the transformer_e1One end of which is connected with the single battery C_ePositive electrode of (2), primary coil of transformer (T)_e1Another end of the switch Q is connected with a Mosfet switch_e1Drain, high reverse voltage schottky diode D_e1Cathode of (2), Mosfet switch Q_e1Source and high reverse voltage schottky diode D_e1Anode of (2) is connected with the single battery C_eOn the negative electrode; transformer secondary coil T_e2One end of which is connected with the single battery C₁Positive electrode of (2), Mosfet switch M_eDrain electrode of (1), secondary winding of transformer (T)_e2Another end of the switch Q is connected with a Mosfet switch_e2Drain, high reverse voltage schottky diode D_e2Cathode of (2), Mosfet switch M_eWith source connected to a high reverse voltage schottky diode G_e1Anode of (2), high reverse voltage schottky diode G_e1Is connected with the single battery C_eOn the positive pole of (2), Mosfet switch Q_e2Source and high reverse voltage schottky diode D_e2Anode of (2) a common diode G_e2Cathode and single cell C_nNegative electrode of (1), high reverse voltage schottky diode G_e2Anode of (2) is connected to the Mosfet switch N_eOn the source of (1), Mosfet switch N_eIs connected with the single battery C_eOn the negative electrode;

the primary coil T of the transformer₁₁One end of which is connected with the single battery C₁Positive electrode of (2), primary coil of transformer (T)₁₁Another end of the switch Q is connected with a Mosfet switch₁₁Drain, high reverse voltage schottky diode D₁₁Cathode of (2), Mosfet switch Q₁₁Source and high reverse voltage schottky diode D₁₁Anode of (2) is connected with the single battery C₁On the negative electrode; transformer secondary coil T₁₂One end of which is connected with the single battery C₁Positive pole of (2), secondary winding of transformer (T)₁₂Another end of the switch Q is connected with a Mosfet switch₁₂Drain, high reverse voltage schottky diode D₁₂Cathode of (2), Mosfet switch Q₁₂Source and high reverse voltage schottky diode D₁₂Are commonly connected to a diode G₁₂Cathode and single cell C_nNegative electrode of (1), high reverse voltage schottky diode G₁₂Anode of (2) is connected to the Mosfet switch N₁On the source of (1), Mosfet switch N₁Is connected with the single battery C₁On the negative electrode;

the primary coil T of the transformer_n1One end of which is connected with the single battery C_nPositive electrode of (2), primary coil of transformer (T)_n1Another end of the switch Q is connected with a Mosfet switch_n1Drain, high reverse voltage schottky diode D_n1Cathode of (2), Mosfet switch Q_n1Source and high reverse voltage schottky diode D_n1Anode of (2) is connected with the single battery C_nOn the negative electrode; transformer secondary coil T_n2One end of which is connected with the single battery C₁Positive electrode of (2), Mosfet switch M_nDrain electrode of (1), secondary winding of transformer (T)_n2Another end of the switch Q is connected with a Mosfet switch_n2Drain, high reverse voltage schottky diode D_n2Cathode of (2), Mosfet switch M_nWith source connected to a high reverse voltage schottky diode G_n1Anode of (2), high reverse voltage schottky diode G_n1Is connected with the single battery C_nOn the positive pole of (2), Mosfet switch Q_n2Source and high reverse voltage schottky diode D_n2Anode of (2) is connected with the single battery C_nOn the negative electrode;

wherein i =1,2,3,. n, j =1,2,3,. n-1, a =2,3,4,. n, b =1,2,3,. n-1, e =2,3,. n-1.

2. The equalizing circuit for parallel charging and bidirectional flyback dual discharge equalization according to claim 1, wherein: the relay is G8N-1L-DC 12.

3. The equalizing circuit for parallel charging and bidirectional flyback dual discharge equalization according to claim 1, wherein: when the equalizing circuit performs charge equalization, if a certain single battery reaches the settingWhen the charging cut-off voltage is reached, controlling the Mosfet switch corresponding to the single battery to be switched off, so that the single battery is isolated out of the charging circuit until all the single batteries reach the charging cut-off voltage, and at the moment, all the single batteries are isolated out of the charging circuit, wherein the charging circuit is in a disconnected state; finally, all the single batteries stop charging due to the fact that the set charging cut-off voltage is reached, and the purpose of forced equalization is achieved; and a single battery C_eThe corresponding Mosfet switch is a Mosfet switch M_eAnd Mosfet switch N_eAnd a single cell C₁The corresponding Mosfet switch is a Mosfet switch N₁And a single cell C_nThe corresponding Mosfet switch is a Mosfet switch M_n。

4. The equalizing circuit for parallel charging and bidirectional flyback dual discharge equalization according to claim 1, wherein: when the equalizing circuit performs discharge equalization, if a certain single battery C exists_xIs the highest SOC single battery in the battery pack and the voltage V thereof_xAnd average voltage V of battery pack_av△ V of the difference₁When not less than α, PWM is adopted to match the single battery C_xCorresponding Mosfet switch Q_x1Performing high-frequency on-off control: when Q is_x1In the on state, the current flows from the single battery C_xThe positive electrode of the transformer flows out and passes through a primary coil T of the transformer_x1Mosfet switch Q_x1Back to the single cell C_xThe negative electrode of (1); when Q is_x1In the off state, the secondary winding T of the transformer is at the moment_x2Inducing corresponding electromotive force current from secondary coil T of transformer_x2One end flows out and returns to the secondary coil T of the transformer through the load_x2The other end, so that the energy in the single battery with the highest SOC is transferred to the battery pack;

if there is a certain single battery C_yIs the lowest SOC single battery of the battery pack and the voltage V thereof_yAnd average voltage V of battery pack_av△ V of the difference₂When not more than β, PWM is adopted to match the single battery C_yCorresponding Mosfet switch Q_y2Performing high-frequency on-off control: when Q is_y2When in the on state, the current is from the monomerBattery C₁The positive pole of the transformer flows out and passes through a secondary coil T of the transformer_y2Mosfet switch Q_y2Back to the single cell C_nThe negative electrode of (1); when Q is_y2In the off state, the primary winding T of the transformer is at the moment_y1Inducing a corresponding electromotive current from the primary winding T of the transformer_y1One end flows out and returns to the primary coil T of the transformer through the load_y1The other end, so that the energy in the battery pack is transferred to the lowest SOC single battery;

wherein,，x,y∈[1,n]，△V₁=V_x—V_av，△V₂=V_y—V_avthe positive numbers α and β each indicate a threshold value.

5. A method of controlling the equalization circuit of parallel charging and bidirectional flyback dual discharge equalization of claim 1, characterized by: the method comprises the following steps of charge equalization and discharge equalization control:

charging equalization: PWM control of all Mosfet switches M_aMosfet switch N_bAre all in a conducting state, and control all the Mosfet switches Q_i1Mosfet switch Q_i2All are in off state, and control the normally closed relay NC_jWhen the single batteries are in a disconnected state, all the single batteries are directly connected to a power supply in parallel, if a certain single battery reaches a set charging cut-off voltage, a Mosfet switch corresponding to the single battery is controlled to be disconnected, so that the single battery is isolated from a charging circuit until all the single batteries finally reach the charging cut-off voltage, and at the moment, all the single batteries are isolated from the charging circuit, and the charging circuit is in a disconnected state; finally, all the single batteries stop charging due to the fact that the set charging cut-off voltage is reached, and the purpose of forced equalization is achieved; and a single battery C_eThe corresponding Mosfet switch is a Mosfet switch M_eAnd Mosfet switch N_eAnd a single cell C₁The corresponding Mosfet switch is a Mosfet switch N₁And a single cell C_nCorresponding Mosfet switchAs a Mosfet switch M_n；

Discharge equalization: PWM control of all Mosfet switches M_aMosfet switch N_bAll the Mosfet switches Q are in an off state and are controlled_i1Mosfet switch Q_i2All are in off state, and control the normally closed relay NC_jWhen the single batteries are in the connection state, all the single batteries are in the series connection state;

if there is a certain single battery C_xIs the highest SOC single battery in the battery pack and the voltage V thereof_xAnd average voltage V of battery pack_av△ V of the difference₁When not less than α, PWM is adopted to match the single battery C_xCorresponding Mosfet switch Q_x1Performing high-frequency on-off control: when Q is_x1In the on state, the current flows from the single battery C_xThe positive electrode of the transformer flows out and passes through a primary coil T of the transformer_x1Mosfet switch Q_x1Back to the single cell C_xThe negative electrode of (1); when Q is_x1In the off state, the secondary winding T of the transformer is at the moment_x2Inducing corresponding electromotive force current from secondary coil T of transformer_x2One end flows out and returns to the secondary coil T of the transformer through the load_x2The other end, so that the energy in the single battery with the highest SOC is transferred to the battery pack;

if there is a certain single battery C_yIs the lowest SOC single battery of the battery pack and the voltage V thereof_yAnd average voltage V of battery pack_av△ V of the difference₂When not more than β, PWM is adopted to match the single battery C_yCorresponding Mosfet switch Q_y2Performing high-frequency on-off control: when Q is_y2In the on state, the current flows from the single battery C₁The positive pole of the transformer flows out and passes through a secondary coil T of the transformer_y2Mosfet switch Q_y2Back to the single cell C_nThe negative electrode of (1); when Q is_y2In the off state, the primary winding T of the transformer is at the moment_y1Inducing a corresponding electromotive current from the primary winding T of the transformer_y1One end flows out and returns to the primary coil T of the transformer through the load_y1The other end, so that the energy in the battery pack is transferred to the lowest SOC single battery;

wherein,，x,y∈[1,n]，△V₁=V_x—V_av，△V₂=V_y—V_avthe positive numbers α and β each indicate a threshold value.