JP2022104486A - Smart charging system and method - Google Patents

Abstract

To provide a charging system and method for optimizing charging steps and conditions for charging a battery and improving charging efficiency and battery life.SOLUTION: A smart charging system 100 includes at least one control module 101 that controls the operation of the system, a power conversion module 103 that is connected to a control module and supplies power to operate the system, a voltage measurement module 107 that measures the battery voltage Vb and inputs it to at least one control module, a pre-charging module 105 that pre-charges with a charging current of 0.01C to 0.5C when the battery voltage Vb is less than the first predetermined range of its upper limit, and a feedback module 113, which is connected to the voltage measurement module and allows the system to control and stabilize the charging voltage by the control module to follow the battery voltage Vb + ΔV. The first predetermined range is 7 to 70% of the upper limit of the battery voltage Vb.SELECTED DRAWING: Figure 2

Description

The present invention relates to smart charging systems and methods, and more particularly to charging systems and methods that optimize charging steps and conditions for charging batteries and improve charging efficiency and battery life.

In recent years, research and development of chargers for electric vehicles has been progressing toward miniaturization and weight reduction. As a result, the difficulty of constructing a charging base is reduced, the conversion efficiency during charging is improved, and the charging speed is also significantly improved. In the current market, constant current-constant voltage (CC-CV) charging methods are widely adopted for lithium battery chargers for electric vehicles. In this method, the battery is charged using a constant current in the constant current stage, and when the charging voltage reaches the upper limit, the method is switched to the constant voltage / current limiting method. Then, the charging current is gradually lowered while maintaining the charging voltage as it is, and the charging process is terminated when the charging current drops for a sufficient time.

However, the above charging method has three drawbacks. First, when the battery is in a low voltage state, if it is charged with a large current from the beginning, the voltage of the battery rises too rapidly in the precharging stage, and as a result, the inside of the battery reacts rapidly and becomes uncontrollable. Become. As a result, the temperature rises rapidly and the battery life is shortened, and in a serious case, an accident such as ignition or explosion occurs. Second, in the precharging stage, when the battery is low voltage, the input current is controlled by the current limiting resistance in a well-known charger, but the voltage across the current limiting resistance changes with the voltage of the battery. Therefore, if the initial charging current is too large, the voltage rises during the charging process, and the amount of change in the precharging current becomes large. However, well-known chargers do not have a control mechanism for such a phenomenon. Furthermore, since the current limiting resistor must withstand high power loss, it is necessary to select a resistor with a high rated power. However, in this case, the heat loss becomes large, which is not suitable for the miniaturized design of the charger. It also has a significant effect on battery life. Finally, as a third drawback, the conventional constant current-constant voltage charging method does not consider the effect of charging temperature on the battery. If the charging current remains constant despite changes in the ambient temperature, charging efficiency will be impaired. If the battery is charged using the original rated current even after the battery capacity is reduced by repeated charging, this relatively large current further shortens the service life of the battery.

As an example of the above-mentioned constant current-constant voltage charging method, Patent Document 1 discloses a management step of a lithium battery for an electric vehicle that monitors and measures a change in a parameter of each lithium battery in real time by an independent control chip. .. Further, in the charging process of FIGS. 3 and 4 of Patent Document 1, the technical features of charging steps such as general trickle charging, constant current charging, and constant voltage charging are discussed. However, similarly to the above, in the process of constant current charging and constant voltage charging, when the battery has a low voltage, the initial chemical reaction inside the battery may proceed too rapidly due to the suddenly input charging current. Even if trickle charging steps were added to the general technology to remedy the problem of the voltage rising too rapidly during the battery precharging stage, the trickle charging performed in small portions would result in no input current. In addition to the risk of stabilization, it also exposes the battery to multiple current pulses. Currently, the battery cost of electric vehicles is still soaring, and there is a limit to how much battery life can be improved.

Chinese Patent Application Publication No. 10209595A

Therefore, based on the above-mentioned drawbacks of the conventional charger, the amount of change in the charging current at the precharging stage is particularly large, which is inconvenient for the miniaturization, safety, charging efficiency and battery life of the charger. , There is room for further improvement in conventional charging methods and chargers.

Means for Solving the Invention

In order to solve the above problems, the present invention provides a smart charging system. The configuration of the system consists of a control module (Micro Control Unit, MCU) that controls the operation of the system, a power conversion module that is connected to the control module and converts the input AC (AC) into the power required by the system, and charging. When the switching module that switches to the required power and the control module are connected and the total capacity of the battery is less than 5% of the total capacity of the battery, that is, when the battery is in a charged state (SOC: State-Of-Change), or When the battery voltage V _b is smaller than the first predetermined range of the upper limit of the battery voltage, the pre-charging module for pre-charging the battery with a current of 0.01 C to 0.5 C, and the battery voltage V _b of the battery. , A voltage measuring module that measures the output voltage _Vipre of the power conversion module and inputs the measurement result to the control module. The above-mentioned C is generally referred to as a C-rate, and is a unit of a ratio representing the magnitude of the current when the battery is charged and discharged.

Subsequently, in one embodiment of the present invention, the voltage measuring module can be installed between the Primary side and Secondary side and the switching module, and between the battery and the switching module, respectively, for different circuit areas in the smart charging system. To measure.

According to the content of the present invention, in the above-mentioned pre-charging stage, the formula of the pre-charging current is I _ipre = (V _ipre -V _b ) / R _precharge in the smart charging system. V _ipre -V _b = ΔV represents the voltage difference between both ends of the precharging module in the first predetermined range as a predetermined parameter, and V _ipre is the input voltage of the precharging module (that is, the output voltage of the power conversion module). ). The formula of the output voltage is _Vipre = V _b + ΔV. V _b represents the battery voltage. R _precharge represents a parameter of current limiting resistance in precharging and can be adjusted according to the desired power magnitude or application scene. Since there is electrical resistance, the output current can be controlled simply by controlling the output voltage of the power conversion module and maintaining a constant voltage difference (ΔV) across the electrical resistance, and the current input to the battery during charging can be controlled. Stabilize.

According to the content of the present invention, the smart charging system includes a temperature measuring module that measures the temperature of the battery and inputs the measured temperature to the control module. As a result, the control module can adjust the magnitude of the precharge current, so that the occurrence of an accident due to the temperature rise inside the battery being too fast can be avoided.

According to the content of the present invention, the smart charging system includes a current measuring module for measuring the charging current _Ib output from the battery.

According to the content of the present invention, the smart charging system includes a feedback module. Further, the control module outputs the control signals I _REF and V _REF based on the battery voltage V _b . In one embodiment of the present invention, the feedback module is connected to the current measurement module and the voltage measurement module, and the signals are associated with the reference signals I _REF and V _REF of the charging current and the battery voltage, respectively, to correct the output power. And control. This allows the smart charging system to stabilize the charging voltage and charging current of the battery at each charging stage.

In order to solve the problems in the conventional charging method, the present invention provides a smart charging method. The method includes the following as a flow. That is, the battery voltage V _b is measured by the voltage measuring module, and the measurement result is input to the control module. The control module determines the stage of the battery condition based on the measurement result of the battery voltage V _b . When the battery voltage V _b is in the first predetermined range, the control module determines that the battery needs to be charged with a current of 0.01C to 0.5C in the precharging stage. When the battery voltage V _b is in the second predetermined range, the control module determines that the battery needs to be charged with a constant current in the constant current stage. When the battery voltage V _b is in the third predetermined range, the control module determines that it is necessary to charge the battery by setting a charging voltage corresponding to a constant voltage in the constant voltage stage. When the current _Ib of the battery decreases and the end condition is reached, the control module determines that the charging is completed and stops charging the battery. The first predetermined range is 7 to 70% of the upper limit of the battery voltage (voltage when the battery is fully charged).

According to the content of the present invention, in the method flow of the smart charging method, the connection status of the battery is further confirmed by the temperature measuring module, and the temperature of the battery is measured. In one embodiment of the present invention, the battery is provided in the thermistor format, the voltage of the battery can be measured by a voltage measuring module, and the battery is not charged when the temperature is higher than a predetermined value.

The detailed description of the present invention and the drawings of the examples described below are for a better understanding of the present invention. However, it should be construed that these are merely references for understanding the application of the present invention and are not intended to limit the present invention to specific embodiments.

FIG. 1 is a diagram illustrating a system configuration of a smart charging system. FIG. 2 is a diagram further illustrating a detailed system configuration of the smart charging system according to the embodiment of the present invention. FIG. 3 shows a power curve at each charging stage when charging using a smart charging system and method. FIG. 4 is a diagram illustrating a method flow of the smart precharging method.

The present invention will be described in detail in terms of preferred examples and viewpoints. The following description presents the details of the particular implementation of the present invention so that the viewer can fully understand the embodiments of these embodiments. However, those skilled in the art should interpret that the present invention can be carried out even under conditions that do not include these details. The present invention can also be operated and implemented by other specific examples. Each of the details detailed herein may be applied according to different needs and may be supplemented or modified in various ways without departing from the spirit of the invention. Further, the present invention will be described from the viewpoint of preferred examples and viewpoints, but such description is for interpreting the structure of the present invention, does not limit the scope of claims of the present invention, and is for explanation. It's just a thing. The terms used in the following description should be interpreted in the broadest sense and rationally, even when used in combination with the detailed description of any particular embodiment of the present invention. Further, it should be noted that the smart charging system and method described in the present invention are preferably applicable to charging a lithium battery. However, those skilled in the art can make modifications based on their usual knowledge in the art and also apply them to other batteries such as hydrocarbon batteries, nickel cadmium batteries, nickel metal hydride batteries and the like. It should be noted that this is also for illustration purposes only and does not limit the scope of claims of the present invention.

An object of the present invention is that in the constant current-constant voltage (CC-CV) charging method widely used in conventional chargers, the battery voltage rises too rapidly when the constant current is first used. It is to improve the situation where the battery life is easily shortened or an accident occurs in a serious case. Further, in the precharging stage, the voltage across the current limiting resistor changes with the voltage of the battery. Therefore, if the initial charge current is too large, the current limiting resistance must withstand a high power loss if the magnitude of the current limiting resistance is constant. For this reason, it is necessary to select a resistor with a high rated power, but it is not suitable for a miniaturized design of a charger because of the large heat loss. In addition, even if a relatively small trickle charge step is used in the precharging process, the input current will be destabilized by the trickle charge performed in small portions, and the battery will be exposed to multiple current pulses. Become. Therefore, in the smart charging system and method proposed in the present invention, the configuration of the conventional charging system and the determination conditions at each charging stage such as the precharging stage, the constant current stage, and the constant voltage stage are further optimized to be described above. It solves the problems of battery life and safety in conventional chargers. The detailed technical means will be specifically described below.

In order to achieve the above object, with reference to FIG. 1, the present invention provides a smart charging system (100). The system consists of a control module (101) that controls the operation of the system, a power conversion module (103) that is connected to the control module (101) and converts the input AC into the power required by the system, and charging. When the switching module (117) that switches to the required power and the control module (101) are connected and the amount of electricity of the battery (111) is less than 5% of the total capacity, or the battery voltage V _b is the first upper limit. When the value is smaller than the predetermined range, the precharging module (105) that precharges the battery with a charging current of 0.01C to 0.5C and the output voltage _Vipre of the voltage module are included, and the measurement result is controlled by the control module (101). ). The first predetermined range is 7 to 70% of the upper limit of the battery voltage V _b (voltage when the battery is fully charged). The second predetermined range is 70 to 97% of the upper limit of the battery voltage V _b , and the third predetermined range is 97% or more of the upper limit of the battery voltage V _b .

Further, in the present invention, the control module (101) is a microcontroller (Micro Control Unit, MCU) in which a central processing unit, a storage device, a timer / counter, and various input / output interfaces are integrated. The control module (101) is integrated and operates in a commonly known manner to provide computational resources in the charging program of the smart charging system (100) and to work with the processing program. From the viewpoint of the present invention, the control module (101) may be one or a plurality, and each includes one or a plurality of microcontrollers. This allows integrated control of each element in the system according to usage needs, or if you want to enhance or separate the functionality of any of the elements, use a dedicated microcontroller. You may control it. For example, in one embodiment of the present invention, one integrated control module (101) may control the operation of the entire smart charging system (100), or the feedback module (113) may be a single control module (101). ), And may have two microprocessors for control. It should be noted that the above is only a preferred embodiment of the present invention and one of ordinary skill in the art will understand that other system elements may also include an independent microcontroller by reading this specification. Is.

According to one embodiment of the present invention, the switching module (117) receives a control signal from the control module (101) according to the need in each charging stage of the battery (111) and requires a battery. Switch to the charging path. This determines whether the power conversion module (103) directly supplies the power required for charging or the precharging module (105) indirectly supplies the power required for the precharging stage. For example, when the battery voltage V _b of the battery (111) is smaller than the first predetermined range of the upper limit, the switching module (117) switches the charging path, so that the precharging module (105) is described above. ) Allows the battery (111) to be precharged with a charging current of 0.01 C to 0.5 C until the battery voltage V _b deviates from the first predetermined range.

See FIG. According to FIG. 2, in the present invention, the smart charging system (100) is a temperature measuring module (111) that measures the temperature of the battery (111) in order to adjust the magnitudes of the precharging voltage and the precharging current in the precharging stage. 109) is included. In one embodiment of the invention, the formula applied to the precharging voltage is:
V _ipre = V _b + ΔV + V (t)
V _ipre represents the output voltage of the power conversion module (103), and V _b represents the battery voltage. ΔV represents the voltage difference between both ends of the precharging module in the case of the first predetermined range as a predetermined parameter, and V (t) represents the temperature correction function. As a result, when the smart charging system (100) is in the precharging stage, the precharging current range of 0.01C to 0.5C can be maintained with respect to the battery (111). In a preferred embodiment of the present invention, when the temperature of the battery (111) is −10 ° C. to 45 ° C., the correction range of the preferred numerical value by V (t) is 0 to 5 V (Volt). As a result, the chemical reaction inside the battery (111) does not proceed too rapidly, and the calorific value of the smart charging system (100) decreases. In addition, there is more room for adjusting the charging voltage and charging current at each charging stage. Therefore, the temperature rises too quickly in the charging process, which does not affect the service life of the battery (111). In addition to being able to achieve the optimum balance between charging speed and service life, the goal of miniaturization of the charger can also be achieved.

According to the content of the present invention, the smart charging system (100) includes a feedback module (113) connected to the current measuring module (115). With reference to FIG. 2, in one embodiment of the present invention, a voltage measuring module (107) connected to the feedback module (113) is also provided between the Primary side and Secondary side and the switching module (117). There is. As a result, based on the situation of the battery voltage V _b and the charging current I _b at each charging stage, the smart charging system (100) uses the control module (101) to change the charging voltage of the power conversion module (103) to the battery voltage V _b . It becomes possible to control to follow + ΔV. Therefore, the charging voltage becomes constant without being excessively changed due to the fluctuation of the electric power input to the power conversion module (103) from the outside, and a stable charging current can be obtained. Further, the magnitude of the charging current can be adjusted according to the temperature of the battery measured by the temperature measuring module (109), and the charging efficiency and life of the battery (111) are also taken into consideration. To illustrate the precharging stage in one embodiment of the present invention, in FIGS. 2 to 3, the control module (101) outputs analog reference signals I _REF and V _REF , respectively. The reference signal is a reference value corresponding to the charging current and the charging voltage in the precharging stage, respectively. The feedback module (113) is a power conversion module (also referred to as a feedback compensation signal) by comparing the difference values between the precharge voltage V _ipre and the reference signals I _REF and V _REF and acquiring an error signal (Comp) (also referred to as a feedback compensation signal). The output voltage of 103) is controlled to stabilize the level of the precharging voltage _Feedback . As a result, in the precharging stage, the battery (111) can be charged at a stable and moderate speed, and after the battery voltage V _b reaches a predetermined condition, it can be converted to the constant current stage. It should be noted that in the above embodiment, it is stated that the control module (101) outputs the reference signals I _REF and V _REF in analog format, but this is not limited to the reference signal in the precharging stage. Since the control module (101) also stores reference values for each charging stage such as a constant current stage and a constant voltage stage, the smart charging system (100) can stably use the battery (111) at any stage. ), It is possible to adjust the magnitude of the charging voltage and charging current based on the charging status. Therefore, even if the health condition of the battery (111) is not good, the usable life can be effectively extended.

According to one embodiment of the present invention, the power conversion module (103) includes a rectifying unit (103a) that converts an externally input power source from alternating current to desired direct current. The above conversion from alternating current to direct current may be full-wave rectification or half-wave rectification, but is not limited to this. Further, the rectifying unit (103a) smoothes the output direct current, improves the power factor, and reduces the harmonic distortion, thereby further improving the electricity supply quality of the smart charging system (100).

In order to solve the problems of the conventional charging method with reference to FIG. 4, the present invention provides a smart charging method (400). The method includes the following as a flow. That is, in the flow (S2), the battery voltage V _b is measured by the voltage measuring module (107), and the measurement result is input to the control module (101). The control module (101) determines at what stage the condition of the battery (111) is based on the measurement result of the battery voltage V _b . In the flow (S4), when the battery voltage V _b is in the first predetermined range, the control module (101) is in the precharging stage, and the battery (111) is charged with a charging current of 0.01C to 0.5C. Determine that it needs to be charged. In the flow (S5), when the battery voltage V _b is in the second predetermined range, the control module (101) needs to charge the battery (111) with a charging current of a constant magnitude in the constant current stage. Judge that there is. In the flow (S6), when the battery voltage V _b is in the third predetermined range, the control module (101) sets a charging current corresponding to a charging voltage of a certain magnitude in the constant voltage stage. It is determined that the battery (111) needs to be charged. In the flow (S7), when the battery voltage V _b reaches the end condition, the control module (101) determines that the charging is completed, and stops charging the battery (111). The first predetermined range is 7 to 70% of the upper limit of the battery voltage (voltage at full charge). The second predetermined range is 70 to 97% of the upper limit of the battery voltage, and the third predetermined range is 97% or more of the upper limit of the battery voltage.

According to one embodiment of the present invention, the smart charging method (400) does not charge when the measured battery voltage V _b is equal to or less than the first predetermined range in the flow (S2). To exemplify the case of a lithium battery generally available on the market, when the power capacity is fully charged, the battery voltage V _b is about 4.2 V (an example is the case where the rated voltage of one cell is 4.2 V). In a normal application, multiple cells are connected in parallel), and when the power capacity is used up, the battery voltage V _b becomes about 3 V. Therefore, when the voltage falls below the first predetermined range (at this time, the magnitude of the battery voltage V _b is about 0.03 V), it is said that the lithium battery is damaged or malfunctions, or an abnormality occurs in the connection status. Conceivable. Therefore, in order to avoid an accident, the flow (S2) does not charge.

According to the content of the present invention, in the smart charging method (400), the connection status of the battery (111) is confirmed by the temperature measuring module (109), the temperature of the battery (111) is measured, and the temperature is determined from the predetermined value. Also includes a non-charging flow (S1) when the temperature rise rate is larger than the temperature gradient. Further, when the smart charging method (400) is the flow (S4), that is, when the battery (111) is in the precharging stage, the charging formulas applied to the precharging voltage and the precharging current are as follows.
V _ipre = V _b + ΔV + V (t)
I _ipre = (V _ipre -V _b ) / R _precharge
V (t) is a correction function for temperature. In another embodiment of the present invention, when the temperature of the battery (111) is −10 ° C. to 45 ° C., the correction range of the preferred numerical value by V (t) is 0 to 5 V (Volt). As a result, when the charging voltage is in the first predetermined range, the battery voltage V _b of the battery (111) can be linked to the temperature condition measured by the temperature measuring module (109). Further, by controlling the output of the power conversion module (103) by this flow, the object of stable precharging current control in the present invention is achieved.

The above description is a preferred embodiment of the present invention. Those skilled in the art should interpret that the above is for the purpose of explaining the present invention and does not limit the scope of rights claimed in the present invention. In addition, the scope of protection of rights is determined based on the scope of claims described later and the equivalent fields. Any modifications or supplements made by one of ordinary skill in the art on the premise that they do not deviate from the spirit or scope of the Patent belong to the equivalent modifications or designs completed in the spirit disclosed in the present invention and are described in the claims described below. Should be included in the range.

100 Smart charging system 101 Control module 103 Power conversion module 103a Rectification unit 105 Pre-charging module 107 Voltage measuring module 109 Temperature measuring module 111 Battery 115 Current measuring module 117 Switching module 113 Feedback module 400 Smart pre-charging method S1 to S7 Method flow

Claims (5)

It is a smart charging system, and as a configuration,
At least one control module that controls the operation of the system,
A power conversion module that is connected to the control module and supplies power to operate the system,
A voltage measuring module that measures the battery voltage V _b and inputs it to the at least one control module.
When the battery voltage V _b is smaller than the first predetermined range of the upper limit, a precharging module that precharges with a charging current of 0.01C to 0.5C and a precharging module.
Includes a feedback module, which is connected to the voltage measuring module and allows the system to control and stabilize the charging voltage by the control module to follow the battery voltage V _b + ΔV.
The first predetermined range is a system in which the upper limit of the battery voltage V _b is 7 to 70%. Further, a temperature measuring module for confirming the connection status of the battery and measuring the temperature of the battery is included, and the stabilization condition of the charging voltage further includes the temperature of the battery measured by the temperature measuring module. The smart charging system described in. The smart charging system according to claim 2, wherein the numerical range of the correction function is 0 to 5 V when the temperature of the battery is −10 ° C. to 45 ° C. It is a smart charging method, and as a flow,
The voltage measuring module measures the battery voltage V _b , and the control module determines the battery status based on the battery voltage V _b .
When the battery voltage V _b is in the first predetermined range, the control module performs a precharging step to charge the battery with a charging current of 0.01C to 0.5C.
When the battery voltage V _b is in the second predetermined range, the control module performs a constant current step.
The second predetermined range is a method in which the upper limit of the battery voltage is 70 to 97%. When the battery voltage V _b is smaller than the first predetermined range, the magnitude of the precharge voltage V _ipre is the sum of the battery voltage V _b + ΔV and the correction function, and the correction function is a function of the battery temperature. The smart charging method described in.

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