CN212543393U

CN212543393U - Bidirectional pulse charging and self-heating circuit for battery

Info

Publication number: CN212543393U
Application number: CN202021147689.8U
Authority: CN
Inventors: 俞峰; 杨麒麟; 刘斌生; 张凤敏
Original assignee: Fujian Scud Power Technology Co Ltd
Current assignee: Fujian Scud Power Technology Co Ltd
Priority date: 2020-06-19
Filing date: 2020-06-19
Publication date: 2021-02-12
Anticipated expiration: 2030-06-19

Abstract

The utility model relates to a bidirectional pulse charging and self-heating circuit of a battery, the external port of which comprises a charging control signal input end, a pulse width modulation signal input end, a positive input end and a negative input end which are respectively used for connecting the positive output end and the negative output end of an external charger, and a positive output end and a negative output end which are respectively used for connecting the positive output end and the negative output end of an external battery pack; its internal circuit includes a charge-discharge circuit driven by pulse width modulation signal in push-pull mode and a charge circuit controlled by charge control signal. The utility model discloses can make the group battery realize that two-way pulse charges to can make the group battery heating through the positive and negative pulse current that produces the group battery.

Description

Bidirectional pulse charging and self-heating circuit for battery

Technical Field

The utility model relates to a lithium battery charging application, especially a two-way pulse of battery charges and self-heating circuit.

Background

In the lithium ion battery industry, because there is polarization effect in the battery charging process, polarization effect can reduce the charge efficiency of battery, shorten the life of battery, and is especially obvious when the battery is in the low temperature environment, and charging can lead to lithium ion battery to take place to analyse lithium on the negative pole in the low temperature environment, not only makes the decay of battery life-span accelerate, can produce lithium dendrite and pierce through the diaphragm and take place the internal short circuit and the security problem appears when serious moreover on the negative pole. Research in the industry finds that when the battery pack is charged by forward current, if a charging mode of transient instantaneous reverse pulse discharge (namely a bidirectional pulse charging mode) is added, the polarization effect of the lithium ion battery can be reduced or even eliminated during charging, so that the charging strength is improved, the charging speed of the lithium ion battery is improved, the lithium ion battery also has the effect of inhibiting the generation of lithium dendrites, and the cycle service life of the lithium ion battery is prolonged. There are many papers reported in the industry, such as "inhibition of lithium dendrite formation by bidirectional pulse charging method" (journal of physical chemistry 2006, 22(9)), "research on high-current pulse charging characteristics of lithium ion power battery" (journal of power supply, 1 month in 2013, 1 st term, institute of electrical engineering in Zhejiang university), "research on pulse optimization charging method of lithium ion battery" (power supply technology, 2019, 07 th term), and so on.

The existing research of the lithium battery industry based on bidirectional pulse charging is mainly based on academic research, a charger for bidirectional pulse charging used in the research adopts a complex switching power supply circuit, the cost is higher, and no product which can be really grounded and can realize industrial application exists. The existing chargers on the market are basically designed based on a constant current/constant voltage mode (namely, a CC/CV mode) and do not have the function of bidirectional pulse charging. For charging in a low-temperature environment of a lithium ion battery, some battery pack products adopt an external heating mode to heat the battery and then charge the battery, the heating efficiency is low, only part of heat generated by heating power can be conducted to the battery, the temperature of an area in the battery pack close to a heat source is high, the temperature of an area far away from the heat source is low, uniform heating is difficult, and in the battery pack without a heating function, charging is prohibited in the low-temperature environment, and the battery pack cannot be charged at low temperature.

Disclosure of Invention

In view of the above, the present invention provides a bidirectional pulse charging and self-heating circuit for a battery, which can realize bidirectional pulse charging for a battery pack and can heat the battery pack by positive and negative pulse currents generated from the battery pack.

The utility model discloses a following scheme realizes: a bidirectional pulse charging and self-heating circuit for a battery comprises a charging control signal input end, a pulse width modulation signal input end, a positive input end and a negative input end which are respectively used for connecting a positive output end and a negative output end of an external charger, and a positive output end and a negative output end which are respectively used for connecting a positive electrode and a negative electrode of an external battery pack; the internal circuit comprises a charge-discharge circuit driven by a pulse width modulation signal in a push-pull mode and a charge circuit controlled by a charge control signal;

the charge-discharge circuit driven by push-pull of the pulse width modulation signal comprises a first resistor R1, a first controllable switch tube V1 and a second controllable switch tube V2; the charging loop controlled by the charging control signal comprises a second resistor R2, a third resistor R3, a diode D1, a third controllable switch tube V3 and a fourth controllable switch tube V4;

the positive input end is respectively connected with a collector or a drain of the first switching tube V1 and an emitter or a source of the fourth switching tube V4, and the negative input end is respectively connected with a collector or a drain of the second switching tube V2 and the negative output end; the charging control signal input end is connected with the cathode of the diode D1; the pulse width modulation signal input end is respectively connected with one end of a first resistor R1 and one end of a second resistor R2; the positive output end is respectively connected with a collector or a drain of the fourth switching tube V4 and an emitter or a source of the first switching tube V1;

the other end of the first resistor R1 is respectively connected with the base set or the grid of the first switch tube V1 and the second switch tube V2; the first switch tube V1 is connected with the emitter or source of the second switch tube V2; the anode of the diode D1 is respectively connected with the other end of the second resistor R2 and the base set or the gate of the third switching tube V3; the emitter or the source of the third switching tube V3 is grounded, the collector or the drain of the third switching tube V3 is connected to one end of a third resistor R3, and the other end of the third resistor R3 is connected to the base set or the gate of the fourth switching tube V4.

Further, an inductor L1 is included, and the inductor L1 is connected in series between the positive output terminal and the emitter or source of the first switching tube V1.

Further, a capacitor C1 is included, and the capacitor C1 is connected in series between the positive output terminal and the emitter or source of the first switch tube V1.

Further, the switch also comprises an inductor L1 and a capacitor C1, wherein the inductor L1 and the capacitor C1 are connected in series to form a branch, and the branch is connected in series between the positive output end and the emitter or the source of the first switching tube V1.

Further, the first to fourth switching tubes V1 to V4 are triodes or fets.

Compared with the prior art, the utility model discloses following beneficial effect has: the utility model discloses can make the group battery heating through the positive and negative pulse current that produces the group battery.

Drawings

Fig. 1 is a schematic diagram of a circuit connection according to an embodiment of the present invention.

Fig. 2 is a current waveform diagram of the bidirectional pulse charging when the PWM duty ratio is 90% according to the embodiment of the present invention.

Fig. 3 is a current waveform diagram of bidirectional pulse charging with CTRL at a low level and PWM duty cycle of 50% according to an embodiment of the present invention.

Fig. 4 is a diagram illustrating an exemplary application of the circuit according to the embodiment of the present invention.

Detailed Description

The present invention will be further explained with reference to the drawings and the embodiments.

As shown in fig. 1, the present embodiment provides a bidirectional pulse charging and self-heating circuit for a battery as shown in fig. 1, wherein the external port includes a charging control signal input terminal, a pulse width modulation signal input terminal, a positive input terminal and a negative input terminal respectively used for connecting with a positive output terminal and a negative output terminal of an external charger, and a positive output terminal and a negative output terminal respectively used for connecting with a positive electrode and a negative electrode of an external battery pack; the internal circuit comprises a charge-discharge circuit driven by a pulse width modulation signal in a push-pull mode and a charge circuit controlled by a charge control signal;

the charge-discharge circuit driven by push-pull of the pulse width modulation signal charges the battery pack when the pulse width modulation signal is at high level and discharges the battery pack when the pulse width modulation signal is at low level; the charging loop controlled by the charging control signal is turned off at low temperature, so that the charging quantity and the discharging quantity of the battery pack in each pulse width modulation signal period are the same, and heat energy is generated in the battery pack.

In this embodiment, the charge-discharge circuit driven by the pulse width modulation signal in a push-pull manner includes a first resistor R1, a first controllable switch V1, and a second controllable switch V2; the charging loop controlled by the charging control signal comprises a second resistor R2, a third resistor R3, a diode D1, a third controllable switch tube V3 and a fourth controllable switch tube V4;

In the present embodiment, the switch further includes an inductor L1, and the inductor L1 is connected in series between the positive output terminal and the emitter or source of the first switching tube V1. Or the capacitor C1 is further included, and the capacitor C1 is connected in series between the positive output end and the emitter or the source of the first switch tube V1. Or the inductor L1 and the capacitor C1 are further included, and the inductor L1 and the capacitor C1 are connected in series to form a branch, and the branch is connected in series between the positive output end and the emitter or the source of the first switching tube V1.

In this embodiment, the first to fourth switching tubes V1 to V4 are transistors or fets. When both transistors are NPN transistors, two transistors may be NPN transistors, and 2 transistors may be PNP transistors, as indicated by the symbols in fig. 1.

The embodiment further provides a control method based on the above bidirectional pulse charging and self-heating circuit for a battery, which specifically comprises the following steps:

when the charging control signal input by the charging control signal input end is high level, in each PWM period, the high level of the PWM signal is a charging positive pulse, and the PWM signal is a discharging negative pulse when the PWM signal is low level, wherein the charging pulse duration is longer than the discharging pulse duration, so that the electric quantity of the battery pack is gradually increased and is in a charging state.

When the charging control signal input by the charging control signal input end is low level, in each PWM period, the PWM signal high level is a charging positive pulse, and the PWM signal is a discharging negative pulse when the PWM signal is low level, wherein the charging pulse duration and the discharging pulse duration are equal, the charging electric quantity of the battery is equal to the discharging electric quantity, the electric quantity of the battery is not increased, at the moment, because the charging current can generate heat power on the internal impedance of the battery, the battery can generate heat, the temperature of the battery gradually rises, and the battery pack is heated due to the existence of the charging current and the discharging current.

Specifically, in this embodiment, the switching tubes are transistors, and the branch includes an inductor L1 and a capacitor C1.

The main functions of each element in the circuit are as follows: in a charge-discharge loop driven by a PWM (pulse width modulation) signal in a push-pull mode, R1 is a base driving current-limiting resistor for driving V1 and V2; v1 and V2 are triodes output in a push-pull mode, L1 is an energy storage inductor and plays a role in limiting current, and C1 is an energy storage capacitor and plays a role in isolating direct current; in the controlled charging loop, D1 plays a role of turning off V3 when the charging control signal is at low level, R2 is the base current-limiting resistor of V3, V3 plays a role of controlling signal level conversion, R3 is the base current-limiting resistor of V4, and V4 is the charging control switch tube.

The working process of the circuit is as follows:

when the CTRL charging control signal at the input terminal is at a high level, if the PWM signal at the input terminal is at a high level, the voltage of the B electrode of the transistor V2 is higher than the E electrode, and V2 is in an off state, the high level of the PWM signal drives the transistors V3 and V1 to be turned on through the resistors R2 and R1, respectively, and after V3 is turned on, the V4 is driven to be turned on through the resistor R3, and at this time, the current at the positive electrode of the charger flows to the positive electrode of the battery pack through the E electrode of the transistor V4 and then flows back to the negative electrode of the charger from the negative electrode of the battery pack, so as; at this time, the charging loop controlled by the charging control signal charges the battery pack through the triode V4; the current of the positive electrode of the charger also flows through the triode V1, the inductor L1 and the capacitor C1 to charge the battery pack instantaneously, the inductor L1 inhibits the instantaneous current from being too large, the current on the inductor increases rapidly, the capacitor C1 is charged positively, and the positive voltage at the two ends of the capacitor C1 increases.

If the PWM signal at the input terminal is low level, the voltage of the B electrode of the transistor V1 is lower than the E electrode at this time, V1 is off state, V2 is on state, the positive electrode of the battery pack goes through the capacitor C1, the inductor L1 and the E electrode of the transistor V2 to the C electrode, and then returns to the negative electrode of the battery pack to discharge, the inductor L1 suppresses the excessive transient current, and the capacitor C1 is charged reversely at this time, so that when the CTRL signal is high level, in each PWM period, the PWM signal is high level positive pulse of charging, and the PWM signal is low level negative pulse of discharging, where the charging pulse duration is longer than the discharging pulse duration, the battery pack is gradually increased to be in charging state, and fig. 2 is a current waveform diagram of bidirectional pulse charging with PWM duty ratio of 90%.

When the CTRL charging control signal at the input terminal is at a low level, the base voltage of transistor V3 is pulled low by diode D1, so that V3 is in an off state, and V4 is also in an off state. At this time, the duty ratio of the PWM signal of the input terminal is 50%, and the frequency of the PWM signal is increased by 5 times, when the PWM signal is at a high level, the voltage of the B electrode of the transistor V2 is higher than the voltage of the E electrode, and V2 is in an off state, the high level of the PWM signal drives the transistor V1 to be turned on through the resistor R2, the current of the positive electrode of the charger also flows through the transistor V1, the inductor L1 and the capacitor C1 to charge the battery pack instantaneously, the current of the inductor L1 increases rapidly, the capacitor C1 is charged in a forward direction, and the forward voltage at two ends of the C1 increases. If the PWM signal at the input terminal is low level, at this time, the voltage of the B electrode of the transistor V1 is lower than the E electrode, V1 is off state, V2 is on state, the positive electrode of the battery pack returns to the negative electrode of the battery pack to discharge through the capacitor C1, the inductor L1 and the E electrode of the conductive transistor V2 to the C electrode, therefore when the CTRL signal is low level, in each PWM period, the high level of the PWM signal is a positive pulse for charging, the low level of the PWM signal is a negative pulse for discharging, wherein the charging and discharging pulse duration is equal, the charging electric quantity and the discharging electric quantity of the battery are equal, the electric quantity of the battery is not increased, at the moment, because the charging current can generate heat power on the internal impedance of the battery, the battery can generate heat, and the temperature of the battery is gradually increased, the battery pack is heated due to the presence of the charging and discharging current, and fig. 3 is a current waveform diagram of bidirectional pulse charging with CTRL at a low level and a PWM duty of 50%.

In practical application, both the CTRL signal and the PWM signal can be generated by a single chip and operated through a driving circuit.

Preferably, the states and functions of the control signals are illustrated in the following table:

as shown in fig. 1, the specific component parameters of this embodiment are, for example, V2 and V4 may be power transistors 2SB772, V1 may be power transistors 2SD882, L1 inductor 22uH, C1 capacitor 22uF, the frequency of the PWM signal may be selected between 1k and 30 k, and D1 is schottky diode SS 14. Fig. 4 is a specific application of a 4-cell series 14.8V lithium ion battery pack, in which a U2 operational amplifier is connected to a thermistor with negative temperature coefficient, the thermistor is attached to the surface of the battery pack, when the temperature is less than 0 ℃, the resistance of the thermistor is greater than 280k, at this time, the U2 operational amplifier outputs low level, the base voltage of V3 is pulled low through D1, and the V4 charging loop is turned off. The U1 is NE555 oscillating circuit, produce the PWM signal with 90% duty ratio, this circuit is when the temperature of the assembled battery is lower than 0 deg.C, the assembled battery is not charged, but the two-way pulse current in each PWM cycle will be because of the heat that the existence of the internal resistance of assembled battery produces, heat the assembled battery, with the rise of the temperature of the assembled battery, the resistance of the thermistor will become small, when the temperature of the assembled battery reaches more than 2 deg.C, the output of the operational amplifier U2 will become the high level, make the charging circuit of V4 conduct, the assembled battery enters the normal charging state, and it is the way of two-way pulse charging. Therefore this scheme has the function to the group battery self-heating, and have the effect that two-way pulse charges, the cost is lower, make the group battery can reduce polarization effect when charging, promote the charging speed, prolong battery cycle life, and can realize the self-heating of group battery when low temperature environment is used, the produced heat of heating power mainly concentrates on inside the battery, the heat utilization ratio of production is high, and the heat is evenly distributed in the battery, thereby make the group battery also can charge under low temperature environment and use, and have the effect of restraining the formation of battery lithium dendrite, the security of battery low temperature use has been improved.

It is worth mentioning that the utility model protects a hardware structure, as for the control method does not require protection. The above is only a preferred embodiment of the present invention. However, the present invention is not limited to the above embodiments, and any equivalent changes and modifications made according to the present invention do not exceed the scope of the present invention, and all belong to the protection scope of the present invention.

Claims

1. A bidirectional pulse charging and self-heating circuit for a battery is characterized in that an external port comprises a charging control signal input end, a pulse width modulation signal input end, a positive input end and a negative input end which are respectively used for connecting a positive output end and a negative output end of an external charger, and a positive output end and a negative output end which are respectively used for connecting a positive electrode and a negative electrode of an external battery pack; the internal circuit comprises a charge-discharge circuit driven by a pulse width modulation signal in a push-pull mode and a charge circuit controlled by a charge control signal;

2. The bi-directional battery pulse charging and self-heating circuit as claimed in claim 1, further comprising an inductor L1, wherein the inductor L1 is connected in series between the positive output terminal and the emitter or source of the first switch tube V1.

3. The bi-directional pulse charging and self-heating circuit for battery as claimed in claim 1, further comprising a capacitor C1, wherein the capacitor C1 is connected in series between the positive output terminal and the emitter or source of the first switch tube V1.

4. The bidirectional pulse charging and self-heating circuit for battery as claimed in claim 1, further comprising an inductor L1 and a capacitor C1, wherein the inductor L1 and the capacitor C1 are connected in series to form a branch, and the branch is connected in series between the positive output terminal and the emitter or source of the first switching tube V1.

5. The bi-directional pulse charging and self-heating circuit as claimed in claim 1, wherein the first to fourth switching tubes V1-V4 are transistors or FETs.