Disclosure of Invention
In view of the above, the present invention aims to provide a portable safe charging system and method for a lithium battery in a low temperature environment, which aims to solve the problem in the prior art that no versatility is provided for heating the lithium battery by heating external devices, and solve the problem in the prior art that no portability is provided for supplying power to a power grid.
The portable system and the method for safely charging the low-temperature battery realize the functions of firstly carrying out alternating current heating on the external low-temperature power-lack battery by using external energy supply, and then carrying out charging after the temperature is recovered, and also have the capability of carrying out charging or heating independently.
The system specifically comprises the following main functional modules:
the low-temperature energy supply device comprises a low-temperature energy supply source, an energy supply source selection switching circuit, a power supply adjusting circuit, a charging control module and an inversion module;
the low-temperature energy supply source is connected with the energy supply source selection switching circuit and used for realizing energy supply source type selection and self-heating gating when the energy supply source is a full-climate battery;
the power supply source selection switching circuit is used for enabling the low-temperature power supply source to generate heat and/or the lithium battery to generate heat automatically according to the type of the lithium battery and the type of the low-temperature power supply source;
the power supply adjusting circuit is used for rectifying, regulating and isolating power frequency alternating current and outputting direct current to charge the lithium battery which completes heating and temperature rise;
the charging control module is used for determining whether a charging condition is met according to the type of the lithium battery and the surface temperature of the lithium battery; if so, stopping heating the low-temperature energy supply source and/or the lithium battery and closing a power supply adjusting circuit for charging; if not, keeping the low-temperature energy supply and/or the lithium battery to continue heating and increasing the temperature; the charging control module may also be used to provide power to a cryogenic energy supply;
the inversion module is used for carrying out direct current charging or providing alternating current excitation for the lithium battery to enable the lithium battery to switch between two states of self heat generation.
Further, the low-temperature energy supply source adopts a full-climate battery and/or a low-temperature-resistant battery, is temporarily connected to the vicinity of the lithium battery through a structural component during charging, or is arranged at the end of the lithium battery to generate heat by utilizing power-frequency alternating current for excitation; thus, the invention has three energy supply modes: the all-weather battery, the low-temperature-resistant battery and the power frequency alternating current can be used as energy supply input of the equipment. The difference is that the all-weather battery needs to utilize self electric energy and self heating sheets for self heating, and finally outputs direct current; the remaining two categories do not require a self-heating step.
Furthermore, the internal resistance of the lithium battery is directly used as a low-temperature heat generating element, and self-heating is carried out by utilizing alternating current excitation without additionally arranging a heating element.
Correspondingly, the invention also provides a portable safe charging method of the lithium battery suitable for the low-temperature environment, which comprises the following steps:
s1, connecting the low-temperature energy supply source input with an energy supply source selection switching circuit; the energy supply selection switching circuit identifies the type of a low-temperature energy supply and the type of a lithium battery, and the charging control module senses the surface temperature of the lithium battery and determines whether the lithium battery is in a low-temperature power shortage state;
s2, providing a corresponding heating mode and setting corresponding heating parameters under the condition that the lithium battery has a heating requirement according to the low-temperature energy supply source, the type of the lithium battery and the temperature sensing result;
and S3, when the surface temperature of the lithium battery rises to be separated from the low-temperature state, providing a corresponding charging mode and setting charging parameters.
Further, when the all-weather battery is used as the low-temperature energy supply source, the all-weather battery is temporarily connected to the position near the lithium battery through a structural component during charging, and the energy supply source selection switching module controls the power supply adjusting module to output direct current to drive the low-temperature energy supply source to generate heat.
Furthermore, the internal resistance of the lithium battery is directly used as a low-temperature energy supply source, and the self-heating is carried out by utilizing alternating current excitation.
Further, the charging control module provides charging power for the low-temperature energy supply source when the low-temperature energy supply source is insufficient.
Compared with the prior art, the invention at least comprises the following advantages:
1) the system and the method provided by the invention use the all-weather battery, the low-temperature-resistant battery and the power frequency alternating current as the energy supply source, and realize the movable and portable heating and charging of the external low-temperature power-loss lithium battery through the equipment;
2) the power frequency alternating current can be used as a power supply source, the external low-temperature power-shortage battery is heated and charged through the equipment, and the power frequency alternating current can be used under the universal standard;
3) when the internal resistance of the lithium battery is directly used as a low-temperature energy supply source, the lithium battery is not required to be provided with related heating equipment for heating, so that the system structure is simplified;
4) the high-frequency alternating current used can ensure that the power-deficient battery does not age quickly under low-temperature heating;
5) the mode of heating first and then charging ensures that the power-deficient battery is not damaged and lithium is separated at low temperature, and the safety of low-temperature charging of the battery is ensured;
6) the power frequency alternating current can be used as a power supply source to directly charge the all-weather battery and the low-temperature-resistant battery, and the rapid charging of the portable battery is realized.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The system of the invention combines the energy supply, the external low-temperature power-loss battery and the portable low-temperature charging equipment; when the all-weather battery is used as an energy supply source, the portable low-temperature charging equipment outputs current to the self heating element to generate heat under the control of the portable low-temperature charging equipment, and the temperature of the all-weather battery is recovered. When other types of low-temperature-resistant batteries or power frequency alternating current are used as energy supplies, the step is not carried out; then, the power supply supplies power, and the portable low-temperature charging equipment controls output alternating current to heat the lithium battery with low-temperature power loss and recovers the temperature; and finally, the portable low-temperature charging equipment controls the output direct current to charge the insufficient-temperature lithium battery with recovered temperature, the equipment structure is shown in figure 1, and the work flow chart is shown in figure 2.
The core structure of each component of the system is as follows:
the low-temperature energy supply device comprises a low-temperature energy supply source, an energy supply source selection switching circuit, a power supply adjusting circuit, a charging control module and an inversion module;
the low-temperature energy supply source is connected with the energy supply source selection switching circuit and used for realizing energy supply source type selection and self-heating gating when the energy supply source is a full-climate battery;
the power supply source selection switching circuit is used for enabling the low-temperature power supply source to generate heat and/or the lithium battery to generate heat automatically according to the type of the lithium battery and the type of the low-temperature power supply source;
the power supply adjusting circuit is used for rectifying, regulating and isolating power frequency alternating current and outputting direct current to charge the lithium battery which completes heating and temperature rise;
the charging control module is used for determining whether a charging condition is met according to the type of the lithium battery and the surface temperature of the lithium battery; if so, stopping heating the low-temperature energy supply source and/or the lithium battery and closing a power supply adjusting circuit for charging; if not, keeping the low-temperature energy supply and/or the lithium battery to continue heating and increasing the temperature; the charging control module may also be used to provide power to a cryogenic energy supply;
the inversion module is used for switching between two self-heating states of the lithium battery by performing direct current charging on the lithium battery or providing alternating current excitation. The system provided by the invention comprises three specific working modes, and the working modes are shown in the figure 3:
a) mode 1: the lithium battery is charged at low temperature by using an external energy supply battery: 28V direct current is provided by an external energy supply battery, and after the 28V direct current is converted into 32V direct current, alternating current is generated through inversion to realize alternating current heating of the lithium battery. When the temperature reaches a proper temperature, the direct current is directly used for charging the lithium battery.
b) Mode 2: using power frequency alternating current as lithium battery low-temperature charging: 220V and 50Hz alternating current is provided through external power frequency alternating current, and after the alternating current is converted into 32V direct current, alternating current is generated through inversion to realize alternating current heating of the lithium battery. When the temperature reaches a proper temperature, the direct current is directly used for charging the lithium battery.
c) Mode 3: the power frequency alternating current is used as a power supply source to charge the all-weather battery and other low-temperature-resistant batteries: 220V and 50Hz alternating current is provided through external power frequency alternating current, and is converted into 32V direct current to be directly output to an energy supply battery for charging.
Mode 1 and mode 2 are used for the lithium cell, and mode 3 is used when the energy supply battery is insufficient. Modes 1 and 2 can realize the first heating and then charging of the external low-temperature power-down battery under different energy sources; mode 3 is the auxiliary application function that can directly use this equipment to carry out the charging through mains frequency alternating current under the power deficiency of energy supply battery.
The heating mode of mode 1 and mode 2 and the charging mode and the parameter setting function of the external low-temperature insufficient-voltage battery can be realized through a device man-machine interaction panel or by connecting an external controller/an upper computer, and the three basic functions of single charging, single heating and charging after heating are included, and the three basic functions can be combined and set to be used according to rules.
a) Single charging function:
1) selecting a charging mode, wherein the charging mode comprises but is not limited to a universal battery charging mode such as constant current charging, constant voltage charging, constant current and constant voltage charging and the like;
2) setting charging parameters including but not limited to cutoff voltage, charging current, charging capacity and other general battery charging parameters
3) And starting charging, and automatically stopping after a set charging end rule is reached.
b) Single heating function:
1) selecting a heating mode, wherein the heating mode comprises but is not limited to heating by a high-frequency alternating current battery such as sine alternating current and square wave alternating current;
2) setting heating parameters including but not limited to cutoff temperature, heating current amplitude, frequency, heating power, type of heated battery, capacity and the like;
3) heating is started, and the heating is automatically stopped after a set heating finishing rule is reached.
c) Charging after heating:
1) setting the charging mode and parameters of the single charging mode and the heating mode and parameters of the single heating mode;
2) starting a single heating mode, and automatically switching to a single charging mode after a set heating end rule is reached;
3) and automatically stopping after the set charging end rule is reached.
The heating of the lithium battery in the mode 1 and the mode 2 is realized by utilizing the internal impedance of the battery and inputting high-frequency alternating current for generating heat, and the energy supply source of the heating is power frequency alternating current or energy supply battery power supply.
The battery can generate heat when a current load is arranged in the battery, and the high-frequency alternating current generates heat from the inside by utilizing the internal impedance under the condition of ensuring that the SOC of the battery is unchanged and not influencing the service life of the battery, so that the heating is uniform and the heat dissipation is small. The heat production rate was calculated as follows:
in the formula: i is the excitation current amplitude, RreThe real part of the impedance of the battery (changing along with temperature and frequency) can be obtained by off-line electrochemical AC impedance spectroscopy.
The heat generation power of the lithium battery alternating current heating is increased along with the increase of the effective value of the heating alternating current. The damage to the battery decreases as the frequency of the heating alternating current increases.
The upper and lower limits of the safe working voltage of the battery are set to be the upper and lower limit values of the rated working voltage of the battery by external heating of alternating current.
The maximum value of the safe working current of the battery is set by external heating of alternating current, and the maximum value is set as follows:
in the formula of UocExpressed as the battery open circuit voltage.
The lithium batteries in the mode 1 and the mode 2 are charged by utilizing power frequency alternating current or an energy supply battery, and the input power is subjected to control output including but not limited to filtering, rectification and voltage transformation conversion to an external insufficient-power battery for charging.
The charging of the energy supply battery in the mode 3 is to utilize external power frequency alternating current, and control output of the external power frequency alternating current after the external power frequency alternating current is subjected to filtering, rectification and transformation conversion is carried out, so that the energy supply battery is charged. The parameter settings thereof are consistent with the charging parameter settings of the mode 1 and the mode 2.
The control power supply of the portable low-temperature charging equipment is realized by the self-contained auxiliary electric energy source of the equipment, and the functions of man-machine interaction, function setting and control, communication, heat dissipation and the like are realized on the basis of the embedded controller. The communication mode includes but is not limited to CAN communication, USB communication, Ethernet communication, and the cooling mode is air cooling.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.