CN206653938U - A kind of electric automobile lithium battery group balance controller - Google Patents

Abstract

The utility model provides an electric vehicle lithium battery pack equalization controller, which includes a DSP controller, an array selection switch and an LC equalization circuit; the DSP controller is composed of a DSP chip and its peripheral circuits; each switch in the array selection switch A group The gate is connected to the DSP controller, the drain is connected to the corresponding lithium battery cell, and the source is connected to one end of the LC equalization circuit; the gate of each switch in group B is connected to the DSP controller, and the drain is connected to the corresponding terminal of group A. The drain of the controllable switch and the source of the lithium battery cell are connected to the other end of the LC balance circuit; in the LC balance circuit, the first inductor and the first diode are connected in series and then connected to the capacitor, and the anode of the first diode is connected to The source and cathode of each switch in group A are connected to the source of each switch in group B through the first inductance. The implementation of the utility model can overcome the problems existing in the prior art, and solve the adverse effects such as over-discharge and service life reduction caused by the inconsistency of the voltage of the lithium battery cells.

Description

A balance controller for electric vehicle lithium battery pack

technical field

The utility model relates to the technical field of electric vehicle batteries, in particular to an equalizing controller for lithium battery packs of electric vehicles.

Background technique

The service life of lithium battery packs for electric vehicles is determined by the number of cycles, but due to the inconsistency of the lithium battery cell voltage, the cycle service life of lithium battery packs is attenuated, so the reduction in the cycle life of lithium battery packs means that lithium battery packs The increase in replacement frequency has resulted in an increase in the consumption cost of electric vehicles. The researchers found that the battery equalization technology is currently the best way to eliminate the inconsistency of the individual voltage of the lithium battery pack, and the purpose is to eliminate the adverse effects caused by the inconsistency of the individual voltage of the lithium battery pack.

In the prior art, balancing methods for lithium battery packs of electric vehicles include passive balancing methods and active balancing methods.

Among them, the passive equalization method is to connect each battery cell and resistor in parallel through a controllable switch, and by controlling the on and off of the controllable switch, the abundant electric energy of each battery cell is consumed to the corresponding resistor, so that each battery The voltage of the single cell achieves the purpose of equalization, but the equalization efficiency of this method is not high, and the lithium battery pack can only be equalized during the charging process.

Among them, the active equalization method includes various methods such as capacitance equalization, inductance equalization and transformer equalization. The essence of capacitance equalization is realized by the voltage difference between the individual batteries, but the actual battery voltage difference is often not large, and a part of the voltage drop will be divided on the controllable switch, resulting in the actual equalization effect is not good. Not good; inductance balance is realized in the form of current, but it is not ideal due to the limitation of controllable switches. During the switching period, the inductance current must have intermittent problems; transformer balance can realize lithium battery cells to lithium battery packs, lithium batteries The balance from the battery pack to the lithium battery cell is effective, but each lithium single battery needs a secondary winding, and a coaxial iron core needs to be bound together with the winding on the lithium battery pack side, which will significantly Increase the volume of the equalizer, and the structure is not easy to realize.

Utility model content

The technical problem to be solved by the embodiment of the utility model is to provide a balance controller for lithium battery packs of electric vehicles, which can overcome the problems existing in the prior art and solve the problem of overcharging and discharging caused by the inconsistency of the individual voltages of lithium battery packs. (over-discharge) and service life reduction and other adverse effects.

The embodiment of the utility model provides a lithium battery pack equalization controller for an electric vehicle, which is used in a lithium battery pack formed by connecting multiple lithium battery cells in series, and includes a DSP controller, an array selection switch and an LC equalization circuit; wherein,

Described DSP controller is connected with described array selection switch, and it is made up of a DSP chip and its peripheral circuit;

The array selection switch includes controllable switches A ₁ ~A _n+1 of group A and controllable switches B ₁ ~B _n+1 of group B; wherein, among the controllable switches A ₁ ~A _n+1 of group A The grid of each controllable switch of the controllable switch is connected with the DSP controller, the drain is connected with a corresponding lithium battery cell, and the source is connected with one end of the LC equalization circuit; the controllable group B The gate of each controllable switch among the switches B ₁ ~B _n+1 is connected to the DSP controller, and the drain is corresponding to the controllable switches A ₁ ~A _n+1 of the group A. The drain of the controllable switch is connected to the corresponding lithium battery cell, and the source is connected to the other end of the LC equalization circuit;

The LC equalization circuit includes a first inductor L, a first diode D, and a capacitor C; wherein, the first inductor L is connected in series with the first diode D and connected in parallel with the capacitor C , and the anode of the first diode D is connected to the source of each controllable switch in the A group of controllable switches A ₁ ~A _n+1 , and the cathode is connected to the first inductor L through the first inductor L The sources of each controllable switch in the group B of controllable switches B ₁ -B _n+1 are connected.

Wherein, the electric vehicle lithium battery pack balance controller also includes a buffer circuit, the buffer circuit is arranged between the array selection switch and the LC balance circuit, including a resistor R ₀ , a second inductance L ₀ and a second Diode D ₀ ; where,

The resistor R ₀ and the second diode D ₀ are connected in series and connected in parallel with the second inductor L ₀ , and the anode of the second diode D ₀ is connected to the LC equalization circuit , the negative pole is connected to the source of each controllable switch in the group A of controllable switches A ₁ -A _n+1 through the resistor R ₀ .

Wherein, the electric vehicle lithium battery pack equalization controller further includes fuses S ₁ ~S _n+1 , and the fuses S ₁ ~S _n+1 are arranged between the array selection switch and the buffer circuit; wherein, One end of each of the fuses S ₁ ~S _n+1 is correspondingly connected to the source of the corresponding controllable switch in the group A controllable switches A ₁ ~A _n+1 , and the fuse S ₁ The other end of each of ~S _n+1 is connected to the buffer circuit.

Implementation of the utility model embodiment has the following beneficial effects:

1. In the embodiment of the utility model, since the LC equalization circuit adopted is an energy transfer type active equalization circuit, it has the advantages of high efficiency, so that the array selection switch is controlled by the PWM signal sent by the DSP controller, and can select the Inconsistent lithium battery cells are balanced to effectively eliminate the adverse effects of overcharge and discharge (over discharge) and service life reduction caused by the inconsistency of lithium battery cell voltage;

2. In the embodiment of the present invention, due to the use of a buffer circuit, the current overshoot during the turn-on period of the controllable switch in the array selection switch can be effectively suppressed;

3. In the embodiment of the present invention, each equalization channel is equipped with a fuse, which can avoid damage to the circuit when the equalization current is too large.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description These are only some embodiments of the present utility model. For those skilled in the art, obtaining other drawings based on these drawings still belongs to the scope of the present utility model without any creative effort.

Fig. 1 is a schematic diagram of a circuit connection of a lithium battery pack equalization controller for an electric vehicle provided by an embodiment of the present invention;

Fig. 2 is a schematic diagram of another circuit connection of a lithium battery pack equalization controller for an electric vehicle provided by an embodiment of the present invention;

Fig. 3 is another circuit connection schematic diagram of an electric vehicle lithium battery pack equalization controller provided by the utility model embodiment;

Fig. 4 is an application scene diagram of balancing between certain two lithium battery cells by an electric vehicle lithium battery pack equalization controller provided by an embodiment of the present invention;

Fig. 5 is a working principle diagram of the first stage in the equalization process of Fig. 4;

Fig. 6 is a working principle diagram of the second stage in the equalization process of Fig. 4;

Fig. 7 is a waveform diagram of the PWM signal sent by the DSP controller when an equalization controller for a lithium battery pack of an electric vehicle provided by an embodiment of the utility model equalizes a certain lithium battery cell based on two stages of operation in Fig. 5 and Fig. 6 .

detailed description

In order to make the purpose, technical solution and advantages of the utility model clearer, the utility model will be further described in detail below in conjunction with the accompanying drawings.

As shown in Figure 1, in the embodiment of the present utility model, a kind of electric vehicle lithium battery pack equalization controller is provided, used in the lithium battery pack that a plurality of lithium battery cells Bat ₁ ~ Bat _n are connected in series, including DSP Controller 1, array selection switch 2 and LC equalization circuit 3; wherein,

DSP controller 1 is connected with array selector switch 2, and it is made up of a DSP chip and its peripheral circuit;

The array selection switch 2 includes controllable switches A ₁ ~A _n+1 of group A and controllable switches B ₁ ~B _n+1 of group B; wherein, among the controllable switches A ₁ ~A _n+1 of group A The gate G of each controllable switch is connected to the DSP controller 1, the drain D is connected to a corresponding lithium battery cell, and the source S is connected to one end of the LC equalization circuit 3; the group B controllable switch B The gate G of each controllable switch in ₁ ~B _n+1 is connected to DSP controller 1, and the drain D is corresponding to the corresponding controllable switch in group A controllable switch A ₁ ~A _n+1 The drain D of the battery is connected to the corresponding lithium battery cell, and the source S is connected to the other end of the LC equalization circuit 3;

The LC equalization circuit 3 includes a first inductor L, a first diode D, and a capacitor C; wherein, the first inductor L is connected in series with the first diode D and connected in parallel with the capacitor C, and the first two The positive pole of the pole tube D is connected to the source S of each controllable switch in the group A controllable switches A ₁ ~A _n+1 , and the negative pole is connected to the group B controllable switches B ₁ ~B _n through the first inductor L The source S of each controllable switch in ₊₁ is connected.

In the embodiment of the present utility model, the LC equalization circuit 3 is responsible for the energy transfer among the individual lithium battery cells, and the array selector switch 2 is used to strobe inconsistent lithium single cells for equalization. wave control.

As shown in Figure 2, in order to effectively suppress the problem of current overshoot during the turn-on period of any controllable switch in the array selection switch 2, the electric vehicle lithium battery pack equalization controller also includes a buffer circuit 4, and the buffer circuit 4 is arranged on Between the array selection switch 2 and the LC equalization circuit 3, including a resistor R ₀ , a second inductor L ₀ and a second diode D ₀ ; wherein,

The resistance R ₀ and the second diode D ₀ are connected in series and connected in parallel with the second inductor L ₀ , and the anode of the second diode D ₀ is connected to the LC equalization circuit 3, and the cathode is connected to the A group through the resistance R ₀ The source S of each controllable switch among the controllable switches A ₁ -A _n+1 is connected.

As shown in Figure 3, in order to avoid damage to the circuit when the balance current is too large, the balance controller of the lithium battery pack of the electric vehicle also includes fuses S ₁ ~S _n+1 , and the fuses S ₁ ~S _n+1 are set in the array selection Between the switch 2 and the buffer circuit 4; wherein, one end of each of the fuses S ₁ ~S _n+1 corresponds to the source of the corresponding controllable switch among the controllable switches A ₁ ~A _n+1 of group A S is connected, and the other end of each of the fuses S ₁ -S _n+1 is connected to the snubber circuit 4 .

As shown in Figure 4 to Figure 7, the working principle of the balance controller of the electric vehicle lithium battery pack in the embodiment of the utility model is further explained:

In Figure 4, the voltage of Bat ₁ of the lithium cell is significantly higher than that of Bat ₃ , indicating that there are inconsistent lithium cells in the lithium battery pack of the electric vehicle. At this time, the two lithium cells need to be balanced, specifically by The LC balance circuit realizes the transfer of energy from Bat ₁ to Bat ₃ , thereby eliminating the inconsistency of the lithium battery pack;

When the equalization process of the two lithium cells in Figure 4 enters the first stage (as shown in Figure 5), the DSP controller sends out a PWM signal (the waveform of the signal is shown in the 0~t ₁ cycle time in Figure 7) The controllable switches A1 and B2 are turned on, the lithium single battery Bat ₁ charges the LC equalization circuit, the equalization current flowing through the inductor L increases linearly, and the LC circuit stores energy;

When the equalization process of the two lithium cells in Figure 4 enters the second stage (as shown in Figure 6), the DSP controller sends out a PWM signal (the waveform of the signal is shown in the t ₁ ~T cycle time in Figure 7) Make the controllable switches B3 and A4 turn on, A1 and B2 turn off, the LC equalization circuit discharges the lithium battery cell Bat ₃ , the equalization current flowing through the inductor L decreases linearly, and finally completes the energy transfer from Bat ₁ to Bat ₃ , so that the two lithium cells are consistent, thereby eliminating the inconsistency of the electric vehicle lithium battery pack.

Implementation of the utility model embodiment has the following beneficial effects:

1. In the embodiment of the utility model, since the LC equalization circuit adopted is an energy transfer type active equalization circuit, it has the advantages of high efficiency, so that the array selection switch is controlled by the PWM signal sent by the DSP controller, and can select the Inconsistent lithium battery cells are balanced, thereby effectively eliminating adverse effects such as overcharge and discharge and service life reduction caused by lithium battery cell voltage inconsistencies;

2. In the embodiment of the present invention, due to the use of a buffer circuit, the current overshoot during the turn-on period of the controllable switch in the array selection switch can be effectively suppressed;

3. In the embodiment of the present invention, a fuse is added to each equalization channel, which can avoid damage to the circuit when the equalization current is too large.

The above mentioned are only the preferred embodiments of the present utility model, which certainly cannot limit the scope of rights of the present utility model. Therefore, equivalent changes made according to the claims of the present utility model still belong to the scope covered by the present utility model.

Claims (3)

1. An electric vehicle lithium battery pack equalization controller is characterized in that, it is used in the lithium battery pack that a plurality of lithium battery cells are connected in series, including a DSP controller, an array selection switch and an LC equalization circuit; wherein, Described DSP controller is connected with described array selection switch, and it is made up of a DSP chip and its peripheral circuit; The array selection switch includes controllable switches A ₁ ~A _n+1 of group A and controllable switches B ₁ ~B _n+1 of group B; wherein, among the controllable switches A ₁ ~A _n+1 of group A The grid of each controllable switch of the controllable switch is connected with the DSP controller, the drain is connected with a corresponding lithium battery cell, and the source is connected with one end of the LC equalization circuit; the controllable group B The gate of each controllable switch among the switches B ₁ ~B _n+1 is connected to the DSP controller, and the drain is corresponding to the controllable switches A ₁ ~A _n+1 of the group A. The drain of the controllable switch is connected to the corresponding lithium battery cell, and the source is connected to the other end of the LC equalization circuit; The LC equalization circuit includes a first inductor L, a first diode D, and a capacitor C; wherein, the first inductor L is connected in series with the first diode D and connected in parallel with the capacitor C , and the anode of the first diode D is connected to the source of each controllable switch in the group A of controllable switches A ₁ ~A _n+1 , and the cathode is connected to the The sources of each controllable switch in the group B of controllable switches B ₁ -B _n+1 are connected. 2. The balance controller of lithium battery pack for electric vehicle as claimed in claim 1, wherein the balance controller for lithium battery pack of electric vehicle also includes a buffer circuit, and the buffer circuit is arranged between the array selection switch and the Between the LC equalization circuit, including resistance R ₀ , second inductance L ₀ and second diode D ₀ ; wherein, The resistor R ₀ and the second diode D ₀ are connected in series and connected in parallel with the second inductor L ₀ , and the anode of the second diode D ₀ is connected to the LC equalization circuit , the negative pole is connected to the source of each controllable switch in the group A of controllable switches A ₁ -A _n+1 through the resistor R ₀ . 3. The balance controller for lithium battery packs for electric vehicles according to claim 2, wherein the balance controller for lithium battery packs for electric vehicles further includes fuses S ₁ ~S _n+1 , and the fuses S ₁ ~S _n+1 is set between the array selection switch and the buffer circuit; wherein, one end of each of the fuses S ₁ ~S _n+1 corresponds to the group A controllable switches A ₁ ~ The sources of the corresponding controllable switches in A _n+1 are connected, and the other end of each of the fuses S ₁ -S _n+1 is connected with the buffer circuit.