CN116321562A - Self-heating control system and method for lithium battery - Google Patents
Self-heating control system and method for lithium battery Download PDFInfo
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Abstract
The invention discloses a self-heating control system and a self-heating control method for a lithium battery, which relate to the field of lithium batteries, wherein a controller is also used for controlling the self-heating circuit of the lithium battery to enter a first heating control mode or a second heating control mode when the self-heating circuit of the lithium battery is connected with an external alternating current power supply module, so that the self-heating circuit of the lithium battery enters a charging and discharging circulation heating mode or a charging, discharging and open-circuit circulation heating mode.
Description
Technical Field
The invention relates to the field of lithium batteries, in particular to a self-heating control system and method for a lithium battery.
Background
Energy crisis and environmental pollution pressure are driving the rapid development of the electric automobile industry. The power lithium ion battery is a core energy component of the electric automobile, and the cost is about 40% of the whole automobile. However, the low temperature can greatly reduce the performance of the lithium ion battery, resulting in an increase in the internal resistance of the battery and a significant decrease in capacity, power and service life. Particularly, lithium precipitation can be caused by charging in a low-temperature environment below zero, and formed lithium dendrites can even penetrate through a diaphragm to cause internal short circuit, so that safety accidents are caused. Therefore, battery low temperature heating technology is a necessary condition to increase the output power and usable capacity of low temperature lithium ion batteries.
At present, a battery low-temperature heating method adopted on a commercial electric automobile is still an external heating method, wherein the external heating method is used for heating the battery from outside through an external heat source, and the external heating method comprises phase change material heating, resistance heating, heat pump heating, peltier effect heating, electrothermal film heating and the like besides air heating and fluid heating. The external heating method is developed based on a mature battery management system, has a simple structure and relatively low realization difficulty, but has low heating speed due to the external heating property, uneven temperature distribution in the battery and low energy utilization rate. In order to make up the limitation of an external heating method, the invention provides a self-heating control system and a self-heating control method for a lithium battery, which utilize internal resistance of the battery to generate heat.
Disclosure of Invention
In order to solve the problems of low heating speed, uneven internal temperature distribution and low energy utilization rate of a battery caused by the property of external heating, the invention provides a self-heating control system of a lithium battery, which comprises the following components:
a controller;
the lithium battery self-heating circuit comprises a lithium ion battery module, a discharging control module, a charging control module and an external alternating current power supply module, wherein:
the discharge control module comprises: the first N-channel MOS tube and the first PWM controller; the discharging control module is connected with the lithium ion battery module to form a discharging control loop; when the lithium battery self-heating circuit is not connected with an external alternating current power supply module, the controller controls the on-off of the first N channel MOS tube by controlling the output high-low level of the first PWM controller so as to control the cycle period of discharging and stopping discharging of the lithium ion battery module, so that intermittent pulse heavy current is generated in a discharging control loop, and the internal resistance temperature of the battery in the lithium ion battery module is increased in the discharging process of the pulse heavy current, so that a large amount of ohmic heat is generated in the battery, and the internal temperature of the battery is increased;
the charging control module comprises a second PWM controller, a second N-channel MOS tube and a first diode; the charging control module is connected with the lithium ion battery module through an external alternating current power supply module and a first diode to form a charging control loop; under the condition that the charging control module is connected with an external alternating current power supply module, the controller controls the on-off of a second N-channel MOS tube by controlling the output of the second PWM controller to control the cycle period of charging and stopping of the external alternating current power supply module to the lithium ion battery module, so that intermittent pulse heavy current is generated in a charging control loop, and the internal resistance temperature of the battery is increased in the process of charging the battery in the lithium ion battery module through the pulse heavy current, so that a large amount of ohmic heat is generated in the battery, and the internal temperature of the battery is increased;
the controller is further used for controlling the lithium battery self-heating circuit to enter a first heating control mode or a second heating control mode when the lithium battery self-heating circuit is connected to the external alternating current power supply module, and the first heating control mode is as follows: the duty ratio of the output of the first PWM controller and the output of the second PWM controller are adjusted through the controller, so that the on-off frequency and the on-off time sequence of the first N-channel MOS tube and the second N-channel MOS tube are adjusted, and the self-heating circuit of the lithium battery enters a discharging and charging circulation heating mode;
the second heating control mode is: the duty ratio output by the first PWM controller and the second PWM controller is adjusted through the controller so as to adjust the on-off frequency and the on-off time sequence of the first N-channel MOS tube and the second N-channel MOS tube, and the self-heating circuit of the lithium battery enters a cyclic heating mode of discharging, charging and opening; the open circuit represents a state when the first N-channel MOS tube and the second N-channel MOS tube are both in cut-off.
Further, the lithium ion battery module includes:
the lithium ion battery, the first resistor and parasitic inductance inside the lithium ion battery; one end of the first resistor is connected with the positive electrode end of the lithium ion battery, and the other end of the first resistor is connected with one end of the parasitic inductor.
Further, the discharge control module further includes: a second resistor; the connection relation of each component in the discharge control loop is specifically as follows:
one end of the second resistor is connected with the negative electrode end of the lithium ion battery, and the other end of the second resistor is connected with the source electrode end of the first N-channel MOS tube; the grid electrode of the first N-channel MOS tube is connected with a first PWM controller; and the drain electrode of the first N-channel MOS tube is connected with the other end of the parasitic inductor.
Further, the charging control module further includes: the third triode and the third resistor; the emitter of the third triode is grounded, the base electrode of the third triode is connected with the second PWM controller, and the collector electrode of the third triode is simultaneously connected with one end of the third resistor and the grid electrode of the second N-channel MOS tube; the source electrode of the second N-channel MOS tube is connected with the positive electrode end of the first diode; the drain electrode of the second N channel MOS tube is connected with the other end of the third resistor; and the negative electrode end of the first diode is connected with the other end of the parasitic inductance in the lithium ion battery module.
Further, the external ac power module includes:
the alternating current power supply and the current processing module are connected and then output a direct current power supply, and the positive electrode of the direct current power supply is connected with the connecting end of the drain electrode of the second N-channel MOS tube and the third resistor so as to input direct current into the charging control loop; the negative electrode end of the direct current power supply is connected with the negative electrode end of the lithium ion battery; the current processing module is used for transforming, rectifying and filtering the power output by the alternating current power supply so as to output a direct current power supply.
Further, the discharge control module further comprises a second capacitor, a fourth resistor and a second diode; one end of the fourth resistor is connected with the positive electrode end of the second diode and then connected to a connecting line between the parasitic inductor and the drain electrode of the first N-channel MOS tube; the other end of the fourth resistor is connected with the negative electrode end of the second diode and then connected with one end of the second capacitor; the other end of the second capacitor is connected to a connecting line between the source electrode of the first N-channel MOS tube and the second resistor.
The invention also provides a self-heating control method of the lithium battery, which comprises the following steps:
judging whether an external alternating current power supply module is connected into a self-heating circuit of the lithium battery or not through a controller, if not, controlling a first PWM controller to output, adjusting the duty ratio of the output of the first PWM controller, and adjusting the on-off frequency and the on-off time sequence of a first N-channel MOS tube, so that the first N-channel MOS tube circularly turns on and off with continuous preset on-time and preset off-time as a period, intermittent pulse heavy current is generated in a discharge control loop, and the temperature of a first resistor is increased in the process of discharging through the pulse heavy current, so that the internal temperature of the lithium ion battery is increased; when the first N-channel MOS tube is in a period of a preset conduction duration, the first N-channel MOS tube is in a conduction state; when the first N channel MOS tube is in a period of a preset cut-off duration, the first N channel MOS tube is in a cut-off state;
if yes, the controller controls the output of the first PWM controller and the second PWM controller so as to control the on-off frequency and the on-off time sequence of the first N-channel MOS tube and the second N-channel MOS tube, so that the lithium battery self-heating circuit generates bidirectional pulse current, and the battery is quickly self-heated.
Further, the controller controls the output of the first PWM controller and the second PWM controller to control the on-off frequency and the on-off time sequence of the first N-channel MOS transistor and the second N-channel MOS transistor, specifically:
the duty ratio of the output of the first PWM controller and the output of the second PWM controller are adjusted through the controller, so that the on-off frequency and the on-off time sequence of the first N-channel MOS tube and the second N-channel MOS tube are adjusted, and the first N-channel MOS tube and the second N-channel MOS tube are circularly on-off with continuous preset discharging duration and preset charging duration as one period; when the first N-channel MOS tube is in a period of a preset discharge duration, the first N-channel MOS tube is in an on state, and the second N-channel MOS tube is in an off state; when the first N-channel MOS tube is in a period of a preset charging duration, the first N-channel MOS tube is in an off state, and the second N-channel MOS tube is in an on state; or:
the duty ratio of the output of the first PWM controller and the output of the second PWM controller are adjusted through the controller, so that the on-off frequency and the on-off time sequence of the first N-channel MOS tube and the second N-channel MOS tube are adjusted, and the first N-channel MOS tube and the second N-channel MOS tube are circularly on-off in a period of continuous preset discharging duration, preset charging duration and preset open-circuit duration; when the first N-channel MOS tube is in a period of a preset discharge duration, the first N-channel MOS tube is in an on state, and the second N-channel MOS tube is in an off state; when the first N-channel MOS tube is in a period of a preset charging duration, the first N-channel MOS tube is in an off state, and the second N-channel MOS tube is in an on state; and when the first N-channel MOS tube and the second N-channel MOS tube are in a period of a preset open-circuit duration, the first N-channel MOS tube and the second N-channel MOS tube are in an off state.
Compared with the prior art, the invention at least has the following beneficial effects:
(1) In the invention, the discharging control module is connected with the lithium ion battery module to form a discharging control loop, when no external power supply exists, the discharging control loop is formed by controlling the cycle period of discharging and stopping discharging of the lithium ion battery module, intermittent pulse heavy current is generated in the discharging control loop, the internal resistance temperature of the battery in the lithium ion battery module is increased in the discharging process of the lithium ion battery module, a large amount of ohmic heat is generated in the battery, thereby realizing the battery temperature rise, the internal heating of the battery is realized in the discharging process of the lithium ion battery by utilizing the internal resistance heat generation mode of the battery, in addition, the charging control module is connected with the lithium ion battery module through a first diode to form the charging control loop, under the condition that the charging control module is connected with the external alternating current power supply module, the cycle period of charging and stopping charging of the lithium ion battery module is controlled, intermittent pulse heavy current is generated in the charging control loop, the internal resistance temperature of the battery is increased in the charging process of the lithium ion battery module by the pulse heavy current, the internal resistance temperature of the battery is increased in the charging process of the battery, the internal resistance temperature of the battery is utilized, the internal resistance heat of the battery is heated in the heating mode of the lithium ion battery in the charging mode, the lithium ion battery is heated by the internal heating mode, and the lithium ion battery is heated in the heating mode or the self-heating mode is heated by the internal heating mode of the lithium ion battery in the charging mode when the lithium battery is connected with the internal heating module or the lithium battery and the heating module in the heating mode, or the heating mode is heated by the heating mode, or the heating mode is connected with the heating mode and the heating mode, the self-heating circuit of the lithium battery as a whole in the invention realizes self-heating of the interior of the battery, cyclic self-heating of discharging and charging in the discharging process of the lithium ion battery, cyclic self-heating of discharging, charging and open-circuit, and solves the problems of low heating speed, uneven temperature distribution in the interior of the battery and low energy utilization rate caused by the attribute of external heating;
(2) In the invention, in the charging and discharging processes, the corresponding PWM controllers enable the discharging control loop and the charging control loop to generate intermittent pulse heavy current, and the intermittent pulse heavy current is used for charging or discharging, so that the pulse heating is realized, and compared with the direct current continuous heating, the pulse heating can provide longer heating performance before the voltage of the battery drops to the cut-off voltage. Secondly, under the condition that the discharge voltage is the same, the heating current of pulse heating can be designed to be higher than that of direct-current continuous heating, and the heating process is faster and safer. The service life of the pulse-heated battery is 2.2 times that of the direct-current continuous heating, the discharge voltage is lower during the direct-current continuous heating, the polarization degree is higher, and the electrode material is easy to crack;
(3) In the invention, the controller controls the output of the first PWM controller and the second PWM controller to control the on-off frequency and the on-off time sequence of the first N-channel MOS tube and the second N-channel MOS tube, so that the self-heating circuit of the lithium battery generates bidirectional pulse current (controls the charging and discharging processes to carry out cyclic switching), thereby realizing the rapid self-heating of the battery, simultaneously maintaining the SOC of the battery and reducing the aging risk of the battery.
Drawings
FIG. 1 is a diagram of a self-heating circuit of a lithium battery;
fig. 2 is a diagram of a discharge control circuit according to the first embodiment;
fig. 3 is a charge control circuit diagram corresponding to the first embodiment;
FIG. 4 is a timing diagram of a discharge control loop;
FIG. 5 is a timing chart of charge and discharge control in a first control mode;
FIG. 6 is a timing chart of charge and discharge control in a second control mode;
fig. 7 is a charge control circuit diagram corresponding to the second embodiment;
fig. 8 is a discharge control circuit diagram according to the second embodiment.
Detailed Description
The following are specific embodiments of the present invention and the technical solutions of the present invention will be further described with reference to the accompanying drawings, but the present invention is not limited to these embodiments.
Example 1
In order to solve the problems of low heating speed, uneven temperature distribution in the battery and low energy utilization rate caused by the property of external heating, and the problems of lower discharge voltage, higher polarization degree and easy cracking of electrode materials during direct current continuous heating, as shown in fig. 1, the invention provides a self-heating control system of a lithium battery, which comprises:
a controller;
the lithium battery self-heating circuit comprises a lithium ion battery module, a discharging control module, a charging control module and an external alternating current power supply module, wherein:
the lithium ion battery module includes:
the lithium ion battery E, the first resistor R1 (namely the internal resistance of the battery) and the parasitic inductance L1 in the lithium ion battery; one end of the first resistor R1 is connected with the positive electrode end of the lithium ion battery E, and the other end of the first resistor R1 is connected with one end of the parasitic inductor L1.
The discharge control module comprises: the first N-channel MOS transistor Q1 and the first PWM controller PWM1; the discharging control module is connected with the lithium ion battery module to form a discharging control loop; when the lithium battery self-heating circuit is not connected with an external alternating current power supply module, the controller controls the on-off of the first N channel MOS tube Q1 by controlling the high-low level output by the first PWM controller PWM1 so as to control the cycle period of discharging and stopping discharging of the lithium ion battery module, so that intermittent pulse heavy current is generated in a discharging control loop, and the internal resistance temperature of the battery in the lithium ion battery module is increased in the discharging process of the pulse heavy current, so that a large amount of ohmic heat is generated in the battery, and the internal temperature of the battery is increased;
as shown in fig. 2, the discharge control module further includes: a second resistor R2; the connection relation of each component in the discharge control loop is specifically as follows:
one end of the second resistor R2 is connected with the negative electrode end of the lithium ion battery E, and the other end of the second resistor R2 is connected with the source electrode end of the first N-channel MOS tube Q1; the grid electrode of the first N-channel MOS tube Q1 is connected with a first PWM controller PWM1; the drain electrode of the first N-channel MOS tube Q1 is connected with the other end of the parasitic inductance L1.
The second resistor R2 is a balance resistor, and serves to prevent a safety problem caused by an excessively low battery terminal voltage.
As shown in fig. 8, the discharge control module further includes a second capacitor C2, a fourth resistor R4, and a second diode D2; one end of the fourth resistor R4 is connected with the positive electrode end of the second diode D2 and then connected to a connecting line between the parasitic inductor L1 and the drain electrode of the first N-channel MOS tube Q1; the other end of the fourth resistor R4 is connected with the negative electrode end of the second diode D2 and then connected with one end of the second capacitor C2; the other end of the second capacitor C2 is connected to a connecting line between the source electrode of the first N-channel MOS tube Q1 and the second resistor R2.
Fig. 8 is a diagram of a discharge control loop according to the second embodiment, which is aimed at ensuring that the voltage across the first N-channel MOS transistor Q1 is in a safe operating region, wherein the second diode D2 is connected in parallel across the fourth resistor R4 of the damping element, and is used for freewheeling the parasitic inductance L1 of the current storage element when the first N-channel MOS transistor Q1 is turned off. The fourth resistor R4, the second diode D2, and the second capacitor C2 form an absorption loop, which is used for reducing the current drop rate in the discharge control loop when the first N-channel MOS Q1 is turned off. When the first N-channel MOS transistor Q1 is turned off, the induced voltage generated on the parasitic inductor L1 forces the second diode D2 to be turned on and realize freewheeling, so that the voltage at two ends of the first N-channel MOS transistor Q1 can be ensured to be in the safe operating region. When the first N-channel MOS transistor Q1 is turned on again, the energy stored in the second capacitor C2 of the charge storage element may be dissipated through the fourth resistor R4 of the damping element.
The charging control module comprises a second PWM controller PWM2, a second N-channel MOS tube Q2 and a first diode D1; the charging control module is connected with the lithium ion battery module through an external alternating current power supply module and a first diode D1 to form a charging control loop; under the condition that the charging control module is connected with an external alternating current power supply module, the controller controls the on-off of a second N-channel MOS tube Q2 by controlling the output of the second PWM controller PWM2 to control the cycle period of charging and stopping of the external alternating current power supply module to the lithium ion battery module, so that intermittent pulse heavy current is generated in a charging control loop, and the internal resistance temperature of the battery is increased in the process of charging the battery in the lithium ion battery module through the pulse heavy current, so that a large amount of ohmic heat is generated in the battery, and the internal temperature of the battery is increased;
the controller is further used for controlling the lithium battery self-heating circuit to enter a first heating control mode or a second heating control mode when the lithium battery self-heating circuit is connected to the external alternating current power supply module, and the first heating control mode is as follows: the duty ratio of the output of the first PWM controller and the output of the second PWM controller are adjusted through the controller, so that the on-off frequency and the on-off time sequence of the first N-channel MOS tube and the second N-channel MOS tube are adjusted, and the self-heating circuit of the lithium battery enters a discharging and charging circulation heating mode; the method comprises the following steps:
the duty ratio output by the first PWM controller and the second PWM controller is adjusted through the controller so as to adjust the on-off frequency and the on-off time sequence of the first N-channel MOS tube and the second N-channel MOS tube, so that the first N-channel MOS tube and the second N-channel MOS tube are circularly on-off with a continuous preset discharging duration and a preset charging duration as a period, and the first N-channel MOS tube and the second N-channel MOS tube enter a discharging and charging circulating heating mode; when the first N-channel MOS tube is in a period of a preset discharge duration, the first N-channel MOS tube is in an on state, and the second N-channel MOS tube is in an off state; when the first N-channel MOS tube is in a period of a preset charging duration, the first N-channel MOS tube is in an off state, and the second N-channel MOS tube is in an on state;
the second heating control mode is: the duty ratio output by the first PWM controller and the second PWM controller is adjusted through the controller so as to adjust the on-off frequency and the on-off time sequence of the first N-channel MOS tube and the second N-channel MOS tube, and the self-heating circuit of the lithium battery enters a cyclic heating mode of discharging, charging and opening; the open circuit represents a state when the first N-channel MOS tube and the second N-channel MOS tube are both in cut-off state; the method comprises the following steps:
the duty ratio output by the first PWM controller and the second PWM controller is adjusted through the controller so as to adjust the on-off frequency and the on-off time sequence of the first N-channel MOS tube and the second N-channel MOS tube, so that the first N-channel MOS tube and the second N-channel MOS tube are circularly on-off in a period of continuous preset discharging duration, preset charging duration and preset open-circuit duration, and the first N-channel MOS tube, the second N-channel MOS tube and the second N-channel MOS tube enter a discharging, charging and open-circuit circulating heating mode; when the first N-channel MOS tube is in a period of a preset discharge duration, the first N-channel MOS tube is in an on state, and the second N-channel MOS tube is in an off state; when the first N-channel MOS tube is in a period of a preset charging duration, the first N-channel MOS tube is in an off state, and the second N-channel MOS tube is in an on state; and when the first N-channel MOS tube and the second N-channel MOS tube are in a period of a preset open-circuit duration, the first N-channel MOS tube and the second N-channel MOS tube are in an off state.
As shown in fig. 3, the charging control module further includes: the third triode Q3 and the third resistor R3; the emitter of the third triode Q3 is grounded, the base is connected with the second PWM controller PWM2, and the collector is simultaneously connected with one end of the third resistor R3 and the grid electrode of the second N-channel MOS tube Q2; the source electrode of the second N-channel MOS tube Q2 is connected with the positive electrode end of the first diode D1; the drain electrode of the second N-channel MOS tube Q2 is connected with the other end of the third resistor R3; the negative terminal of the first diode D1 is connected to the other terminal of the parasitic inductance L1 in the lithium ion battery module.
Specifically, when the external ac power module is connected, the controller is used to control the high and low level of the PWM2 to control the on and off of the Q3 and thus control the on and off of the Q2. When the output of the PWM2 is at a high level, Q3 is turned on, the gate voltage of Q2 is close to 0, and Q2 is turned off; when the output of the PWM2 is at a low level, Q3 is cut off, and the pull-up resistor R3 pulls up the gate voltage of the Q2 to enable the Q2 to be conducted, and current flows through the Q2, D1, L1 and R1 to charge the lithium ion battery E.
The charging control module according to the present invention further includes another embodiment, and the circuit diagram of the charging control loop formed by connecting the external ac power module and the lithium ion battery module through the first diode D1 is shown in fig. 7.
In fig. 7, Q4 is a P-channel MOS transistor, and when the output of PWM2 is at a low level, Q4 is turned on, and the controller controls on/off of Q4 by controlling PWM2, so as to perform intermittent high-current pulse charging.
The external ac power module includes:
the charging control circuit comprises an alternating current power supply U and a current processing module, wherein the alternating current power supply U is connected with the current processing module and then outputs a direct current power supply, and the positive end V+ of the direct current power supply is connected with the connecting end of a drain electrode Q2 of a second N-channel MOS tube and a third resistor R3 so as to input direct current into the charging control circuit; the negative electrode end V-of the direct current power supply is connected to the negative electrode end of the lithium ion battery E; the current processing module is used for transforming, rectifying and filtering the power output by the alternating current power supply so as to output a direct current power supply.
In the invention, the discharging control module is connected with the lithium ion battery module to form a discharging control loop, when no external power supply exists, the discharging control loop is formed by controlling the cycle period of discharging and stopping discharging of the lithium ion battery module, intermittent pulse heavy current is generated in the discharging control loop, the internal resistance temperature of the battery in the lithium ion battery module is increased in the discharging process of the lithium ion battery module, a large amount of ohmic heat is generated in the battery, thereby realizing the battery temperature rise, the internal heating of the battery is realized in the discharging process of the lithium ion battery by utilizing the internal resistance heat generation mode of the battery, in addition, the charging control module is connected with the lithium ion battery module through a first diode to form the charging control loop, under the condition that the charging control module is connected with the external alternating current power supply module, the cycle period of charging and stopping charging of the lithium ion battery module is controlled, intermittent pulse heavy current is generated in the charging control loop, the internal resistance temperature of the battery is increased in the charging process of the lithium ion battery module by the pulse heavy current, the internal resistance temperature of the battery is increased in the charging process of the battery, the internal resistance temperature of the battery is utilized, the internal resistance heat of the battery is heated in the heating mode of the lithium ion battery in the charging mode, the lithium ion battery is heated by the internal heating mode, and the lithium ion battery is heated in the heating mode or the self-heating mode is heated by the internal heating mode of the lithium ion battery in the charging mode when the lithium battery is connected with the internal heating module or the lithium battery and the heating module in the heating mode, or the heating mode is heated by the heating mode, or the heating mode is connected with the heating mode and the heating mode, the self-heating circuit of the lithium battery as a whole in the invention realizes self-heating of the interior of the battery, cyclic self-heating of charging and discharging, cyclic self-heating of charging, discharging and open-circuit in the discharging process of the lithium ion battery, and solves the problems of low heating speed, uneven temperature distribution in the interior of the battery and low energy utilization rate caused by the attribute of external heating.
Example two
The invention also provides a self-heating control method of the lithium battery, which comprises the following steps:
judging whether an external alternating current power supply module is connected into a self-heating circuit of the lithium battery or not through a controller, if not, controlling a first PWM controller to output, adjusting the duty ratio of the output of the first PWM controller to adjust the on-off frequency and the on-off time sequence of a first N-channel MOS tube Q1, and circularly switching on and off the first N-channel MOS tube Q1 with continuous preset on-time and preset off-time as one period (shown in figure 4) so as to generate intermittent pulse heavy current in a discharge control loop, wherein the first resistance temperature is increased in the process of discharging through the pulse heavy current, and thus the internal temperature of the lithium ion battery is increased; when the first N-channel MOS transistor Q1 is in a period of a preset conduction duration, the first N-channel MOS transistor Q1 is in a conduction state; when the first N channel MOS transistor Q1 is in a period of a preset cut-off duration, the first N channel MOS transistor Q1 is in a cut-off state;
in fig. 4, the discharge duration is the preset on duration of the first N-channel MOS transistor, and during discharge, Q1 is turned on and Q2 is kept off; and the cut-off time is the preset cut-off time of the first N channel MOS tube, and when the discharge is cut-off, Q1 and Q2 are cut-off.
If yes, the controller controls the output of the first PWM controller and the second PWM controller to control the on-off frequency and the on-off time sequence of the first N-channel MOS tube Q1 and the second N-channel MOS tube Q2, so that the lithium battery self-heating circuit generates bidirectional pulse current, and the battery is quickly self-heated.
In the invention, in the charging and discharging processes, the corresponding PWM controllers enable the discharging control loop and the charging control loop to generate intermittent pulse heavy current, and the intermittent pulse heavy current is used for charging or discharging, so that the pulse heating is realized, and compared with the direct current continuous heating, the pulse heating can provide longer heating performance before the voltage of the battery drops to the cut-off voltage. Secondly, under the condition that the discharge voltage is the same, the heating current of pulse heating can be designed to be higher than that of direct-current continuous heating, and the heating process is faster and safer. The service life of the pulse heating battery is 2.2 times that of the direct current continuous heating battery, the discharge voltage is lower when the direct current continuous heating battery is used for continuous heating, the polarization degree is higher, and the electrode material is easy to crack.
The controller controls the output of the first PWM controller and the second PWM controller to control the on-off frequency and the on-off time sequence of the first N-channel MOS tube Q1 and the second N-channel MOS tube Q2, specifically:
the duty ratio of the output of the first PWM controller and the output of the second PWM controller are adjusted through the controller, so that the on-off frequency and the on-off time sequence of the first N-channel MOS tube Q1 and the second N-channel MOS tube Q2 are adjusted, and the first N-channel MOS tube Q1 and the second N-channel MOS tube Q2 are circularly on-off with continuous preset discharging time length and preset charging time length as a period (shown in fig. 5); when the first N-channel MOS tube Q1 is in a conducting state and the second N-channel MOS tube Q2 is in a cut-off state in a period of a preset discharge duration; when the first N-channel MOS tube Q1 is in a cut-off state and the second N-channel MOS tube Q2 is in a conduction state in a period of a preset charging duration;
in fig. 5, the discharge time is a preset discharge duration, and Q1 is turned on and Q2 is turned off during discharge; the charging time is preset charging time, and when charging, Q1 is cut off and Q2 is conducted.
In the invention, the controller controls the output of the first PWM controller and the second PWM controller to control the on-off frequency and the on-off time sequence of the first N-channel MOS tube Q1 and the second N-channel MOS tube Q2, so that the self-heating circuit of the lithium battery generates bidirectional pulse current (controls the charging and discharging processes to carry out cyclic switching), thereby realizing the rapid self-heating of the battery, maintaining the SOC of the battery and reducing the aging risk of the battery.
Or:
the duty ratio of the output of the first PWM controller and the output of the second PWM controller are adjusted through the controller, so that the on-off frequency and the on-off time sequence of the first N-channel MOS tube Q1 and the second N-channel MOS tube Q2 are adjusted, and the first N-channel MOS tube Q1 and the second N-channel MOS tube Q2 are circularly on-off in a cycle with continuous preset discharging duration, preset charging duration and preset open-circuit duration (shown in fig. 6); when the first N-channel MOS tube Q1 is in a conducting state and the second N-channel MOS tube Q2 is in a cut-off state in a period of a preset discharge duration; when the first N-channel MOS tube Q1 is in a cut-off state and the second N-channel MOS tube Q2 is in a conduction state in a period of a preset charging duration; when the first N-channel MOS transistor Q1 and the second N-channel MOS transistor Q2 are in the period of the preset open-circuit duration, both are in the off state.
In fig. 6, the cut-off time is a preset open-circuit duration, and when cut-off, Q1 and Q2 are both in cut-off state.
The invention adjusts the on-off frequency and the on-off time sequence of the Q1 and the Q2 by controlling the output of the PWM1 and the PWM2 through the controller so that the lithium ion battery is circularly switched between three states of charge/discharge/open circuit, thereby realizing the rapid heating of the interior of the battery.
It should be noted that all directional indicators (such as up, down, left, right, front, and rear … …) in the embodiments of the present invention are merely used to explain the relative positional relationship, movement, etc. between the components in a particular posture (as shown in the drawings), and if the particular posture is changed, the directional indicator is changed accordingly.
Furthermore, descriptions such as those referred to herein as "first," "second," "a," and the like are provided for descriptive purposes only and are not to be construed as indicating or implying a relative importance or an implicit indication of the number of features being indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present invention, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.
In the present invention, unless specifically stated and limited otherwise, the terms "connected," "affixed," and the like are to be construed broadly, and for example, "affixed" may be a fixed connection, a removable connection, or an integral body; can be mechanically or electrically connected; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.
In addition, the technical solutions of the embodiments of the present invention may be combined with each other, but it is necessary to be based on the fact that those skilled in the art can implement the technical solutions, and when the technical solutions are contradictory or cannot be implemented, the combination of the technical solutions should be considered as not existing, and not falling within the scope of protection claimed by the present invention.
Claims (8)
1. A lithium battery self-heating control system, comprising:
a controller;
the lithium battery self-heating circuit comprises a lithium ion battery module, a discharging control module, a charging control module and an external alternating current power supply module, wherein:
the discharge control module comprises: the first N-channel MOS tube and the first PWM controller; the discharging control module is connected with the lithium ion battery module to form a discharging control loop; when the lithium battery self-heating circuit is not connected with an external alternating current power supply module, the controller controls the on-off of the first N channel MOS tube by controlling the output high-low level of the first PWM controller so as to control the cycle period of discharging and stopping discharging of the lithium ion battery module, so that intermittent pulse heavy current is generated in a discharging control loop, and the internal resistance temperature of the battery in the lithium ion battery module is increased in the discharging process of the pulse heavy current, so that a large amount of ohmic heat is generated in the battery, and the internal temperature of the battery is increased;
the charging control module comprises a second PWM controller, a second N-channel MOS tube and a first diode; the charging control module is connected with the lithium ion battery module through an external alternating current power supply module and a first diode to form a charging control loop; under the condition that the charging control module is connected with an external alternating current power supply module, the controller controls the on-off of a second N-channel MOS tube by controlling the output of the second PWM controller to control the cycle period of charging and stopping of the external alternating current power supply module to the lithium ion battery module, so that intermittent pulse heavy current is generated in a charging control loop, and the internal resistance temperature of the battery is increased in the process of charging the battery in the lithium ion battery module through the pulse heavy current, so that a large amount of ohmic heat is generated in the battery, and the internal temperature of the battery is increased;
the controller is further used for controlling the lithium battery self-heating circuit to enter a first heating control mode or a second heating control mode when the lithium battery self-heating circuit is connected to the external alternating current power supply module, and the first heating control mode is as follows: the duty ratio output by the first PWM controller and the second PWM controller is adjusted through the controller so as to adjust the on-off frequency and the on-off time sequence of the first N-channel MOS tube and the second N-channel MOS tube, and the self-heating circuit of the lithium battery enters a charge and discharge cyclic heating mode;
the second heating control mode is: the duty ratio output by the first PWM controller and the second PWM controller is adjusted through the controller so as to adjust the on-off frequency and the on-off time sequence of the first N-channel MOS tube and the second N-channel MOS tube, and the self-heating circuit of the lithium battery enters a cyclic heating mode of charging, discharging and opening a circuit; the open circuit represents a state when the first N-channel MOS tube and the second N-channel MOS tube are both in cut-off.
2. The lithium battery self-heating control system according to claim 1, wherein the lithium ion battery module comprises:
the lithium ion battery, the first resistor and parasitic inductance inside the lithium ion battery; one end of the first resistor is connected with the positive electrode end of the lithium ion battery, and the other end of the first resistor is connected with one end of the parasitic inductor.
3. The lithium battery self-heating control system according to claim 2, wherein the discharging control module further comprises: a second resistor; the connection relation of each component in the discharge control loop is specifically as follows:
one end of the second resistor is connected with the negative electrode end of the lithium ion battery, and the other end of the second resistor is connected with the source electrode end of the first N-channel MOS tube; the grid electrode of the first N-channel MOS tube is connected with a first PWM controller; and the drain electrode of the first N-channel MOS tube is connected with the other end of the parasitic inductor.
4. The lithium battery self-heating control system according to claim 3, wherein the charging control module further comprises: the third triode and the third resistor; the emitter of the third triode is grounded, the base electrode of the third triode is connected with the second PWM controller, and the collector electrode of the third triode is simultaneously connected with one end of the third resistor and the grid electrode of the second N-channel MOS tube; the source electrode of the second N-channel MOS tube is connected with the positive electrode end of the first diode; the drain electrode of the second N channel MOS tube is connected with the other end of the third resistor; and the negative electrode end of the first diode is connected with the other end of the parasitic inductance in the lithium ion battery module.
5. The lithium battery self-heating control system according to claim 4, wherein the external ac power module comprises:
the alternating current power supply and the current processing module are connected and then output a direct current power supply, and the positive electrode of the direct current power supply is connected with the connecting end of the drain electrode of the second N-channel MOS tube and the third resistor so as to input direct current into the charging control loop; the negative electrode end of the direct current power supply is connected with the negative electrode end of the lithium ion battery; the current processing module is used for transforming, rectifying and filtering the power output by the alternating current power supply so as to output a direct current power supply.
6. The lithium battery self-heating control system according to claim 5, wherein the discharge control module further comprises a second capacitor, a fourth resistor and a second diode; one end of the fourth resistor is connected with the positive electrode end of the second diode and then connected to a connecting line between the parasitic inductor and the drain electrode of the first N-channel MOS tube; the other end of the fourth resistor is connected with the negative electrode end of the second diode and then connected with one end of the second capacitor; the other end of the second capacitor is connected to a connecting line between the source electrode of the first N-channel MOS tube and the second resistor.
7. The self-heating control method for the lithium battery is characterized by comprising the following steps of:
judging whether an external alternating current power supply module is connected into a self-heating circuit of the lithium battery or not through a controller, if not, controlling a first PWM controller to output, adjusting the duty ratio of the output of the first PWM controller, and adjusting the on-off frequency and the on-off time sequence of a first N-channel MOS tube, so that the first N-channel MOS tube circularly turns on and off with continuous preset on-time and preset off-time as a period, intermittent pulse heavy current is generated in a discharge control loop, and the temperature of a first resistor is increased in the process of discharging through the pulse heavy current, so that the internal temperature of the lithium ion battery is increased; when the first N-channel MOS tube is in a period of a preset conduction duration, the first N-channel MOS tube is in a conduction state; when the first N channel MOS tube is in a period of a preset cut-off duration, the first N channel MOS tube is in a cut-off state;
if yes, the controller controls the output of the first PWM controller and the second PWM controller so as to control the on-off frequency and the on-off time sequence of the first N-channel MOS tube and the second N-channel MOS tube, so that the lithium battery self-heating circuit generates bidirectional pulse current, and the battery is quickly self-heated.
8. The method for controlling self-heating of a lithium battery according to claim 7, wherein the controller controls the outputs of the first PWM controller and the second PWM controller to control the on-off frequency and the on-off time sequence of the first N-channel MOS transistor and the second N-channel MOS transistor, specifically:
the duty ratio of the output of the first PWM controller and the output of the second PWM controller are adjusted through the controller, so that the on-off frequency and the on-off time sequence of the first N-channel MOS tube and the second N-channel MOS tube are adjusted, and the first N-channel MOS tube and the second N-channel MOS tube are circularly on-off with continuous preset discharging duration and preset charging duration as one period; when the first N-channel MOS tube is in a period of a preset discharge duration, the first N-channel MOS tube is in an on state, and the second N-channel MOS tube is in an off state; when the first N-channel MOS tube is in a period of a preset charging duration, the first N-channel MOS tube is in an off state, and the second N-channel MOS tube is in an on state; or:
the duty ratio of the output of the first PWM controller and the output of the second PWM controller are adjusted through the controller, so that the on-off frequency and the on-off time sequence of the first N-channel MOS tube and the second N-channel MOS tube are adjusted, and the first N-channel MOS tube and the second N-channel MOS tube are circularly on-off in a period of continuous preset discharging duration, preset charging duration and preset open-circuit duration; when the first N-channel MOS tube is in a period of a preset discharge duration, the first N-channel MOS tube is in an on state, and the second N-channel MOS tube is in an off state;
when the first N-channel MOS tube is in a period of a preset charging duration, the first N-channel MOS tube is in an off state, and the second N-channel MOS tube is in an on state; and when the first N-channel MOS tube and the second N-channel MOS tube are in a period of a preset open-circuit duration, the first N-channel MOS tube and the second N-channel MOS tube are in an off state.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117293423A (en) * | 2023-11-22 | 2023-12-26 | 江苏欧力特能源科技有限公司 | Low-temperature cold start system and control method of lithium battery |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117293423A (en) * | 2023-11-22 | 2023-12-26 | 江苏欧力特能源科技有限公司 | Low-temperature cold start system and control method of lithium battery |
| CN117293423B (en) * | 2023-11-22 | 2024-01-30 | 江苏欧力特能源科技有限公司 | Low-temperature cold start system and control method of lithium battery |
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