TWI886881B - Battery charging method and device - Google Patents

Abstract

The present disclosure provides a battery charging method and device. The battery charging method includes: during a first time period of a charging cycle, disposing a DC current generating circuit to generate a DC current, and utilizing the DC current as a charging current to charge a battery; and during a second time period of the charging cycle, disposing a sinusoidal current generating circuit to generate a sinusoidal current, and utilizing the DC current and the sinusoidal current as the charging current to charge the battery. A minimum value of the charging current is equal to the DC current.

Description

Battery charging method and device

This case relates to a charging method and device, and in particular to a battery charging method and device.

The common battery charging method uses a constant current and constant voltage charging method to ensure that the battery is fully charged. However, with today's demand for fast charging, the charging time must be effectively reduced while preventing the battery from heating up too high during charging and reducing the battery life.

Therefore, it is an urgent need to invent a battery charging method and device that can improve the above-mentioned prior art.

The purpose of this case is to provide a battery charging method and device to solve the above-mentioned technical problems.

To achieve the above-mentioned purpose, the present case provides a battery charging method, comprising: in the first period of the charging cycle, a DC current generating circuit is set to generate a DC current, and the DC current is used as the charging current to charge the battery; and in the second period of the charging cycle, a sine wave current generating circuit is set to generate a sine wave current, and the DC current and the sine wave current are used as the charging current to charge the battery; wherein the minimum value of the charging current is equal to the DC current.

To achieve the above-mentioned purpose, the present invention further provides a battery charging device, comprising a sine wave current generating circuit, a DC current generating circuit and a control circuit. The control circuit is coupled to the sine wave current generating circuit and the DC current generating circuit. In the first period of the charging cycle, the control circuit sets the DC current generating circuit to generate a DC current, and uses the DC current as the charging current to charge the battery. In the second period of the charging cycle, the control circuit sets the sine wave current generating circuit to generate a sine wave current, and uses the DC current and the sine wave current as the charging current to charge the battery. The minimum value of the charging current is equal to the DC current.

The above-mentioned embodiments can effectively reduce the charging time of the battery and can achieve a balance between the charging speed and the temperature to maintain the life of the battery.

Some typical embodiments that embody the features and advantages of the present invention will be described in detail in the following description. It should be understood that the present invention can have various variations in different aspects without departing from the scope of the present invention.

FIG. 1 is a schematic diagram of a battery charging device and a battery in an embodiment of the present invention. As shown in FIG. 1 , the battery charging device 1 is configured to charge a battery 2. In this embodiment, the battery charging device 1 includes a control circuit 10, a sine wave current generating circuit 11, a DC current generating circuit 12, a battery impedance measuring circuit 13, and a frequency generating circuit 14. In order to make the drawing concise and easy to explain, other components of the battery charging device 1 are not shown in FIG. 1 . In this embodiment, the battery charging device 1 is divided into a control circuit 10, a sine wave current generating circuit 11, a direct current generating circuit 12, a battery impedance measuring circuit 13 and a frequency generating circuit 14 to clearly illustrate the operation of the battery charging device 1. The above circuits can be implemented by using appropriate circuit elements respectively, or can be integrated or implemented by one or more circuit elements respectively. For example, the control circuit 10 and the battery impedance measuring circuit 13 are implemented by integrating into the same microcontroller, while the sine wave current generating circuit 11 and the direct current generating circuit 12 are integrated into the same current generating circuit, and provide the required charging current according to the setting of the control circuit 10. In another embodiment, the control circuit 10, the sine wave current generating circuit 11 and the DC current generating circuit 12 may also be a same circuit composed of discrete components and/or integrated circuit components to perform the functions of the above three components. The control circuit 10 may include components such as logic circuits to control the operation of the sine wave current generating circuit 11, the DC current generating circuit 12, the battery impedance measuring circuit 13 and the frequency generating circuit 14. For example, the control circuit 10 may set the sine wave current generating circuit 11 to generate the sine wave current Is and the DC current generating circuit 12 to generate the DC current Idc at an appropriate time point according to the signal of the frequency generating circuit 14. The DC current generating circuit 12 may adopt a suitable circuit structure such as a DC-DC converter or an AC-DC converter to provide the required DC current Idc. In one embodiment, the frequency generating circuit 14 includes an oscillating circuit and outputs one or more fixed-frequency periodic signals, so that the control circuit 10 can estimate time according to the one or more periodic signals and set the operation of other circuit blocks accordingly, such as controlling the time period of the sine wave current generating circuit 11 to generate the sine wave current Is and the frequency of the generated sine wave current Is.

In the process of charging the battery 2 with the sine wave current Is, the frequency of the sine wave current Is is related to the battery charging speed and the temperature rise. FIG. 2 shows an embodiment of the AC impedance model of the battery 2. As shown in FIG. 2, in this AC impedance model, the equivalent impedance Z includes the ohmic resistance Ro, the equivalent capacitor Cd, the electrode inductance Ld and the ideal battery Batt connected in series, and the equivalent capacitor Cd is connected in parallel to the resistor Rcf. From this model, it can be seen that when the battery 2 is charged with the sine wave current Is, if the frequency of the sine wave current Is changes, the equivalent impedance Z of the battery 2 also changes accordingly. The control circuit 10 can appropriately set the frequency of the sine wave current Is generated by the sine wave current generating circuit 11 to match the equivalent impedance Z of the battery 2 as much as possible, thereby reducing energy loss to improve charging efficiency and reducing temperature increase caused by waste heat.

In view of this, in this embodiment, the control circuit 10 can be provided with a battery impedance measuring circuit 13 to measure the equivalent impedance Z of the battery 2. Based on the equivalent impedance Z of the battery 2, the control circuit 10 sets the frequency of the sine wave current Is generated by the sine wave current generating circuit 11 to match the equivalent impedance Z of the battery 2, so that the charging current Io charges the battery 2 with better efficiency, thereby further improving the charging efficiency. For example, the frequency of the sine wave current Is makes the equivalent impedance Z of the battery 2 close to the minimum value, thereby obtaining a greater energy transfer efficiency, and at the same time can prevent the temperature of the battery 2 from rising significantly to improve the service life. For example, the control circuit 10 may configure the sine wave current generating circuit 11 to send a sine wave signal of one frequency to the battery 2, and configure the battery impedance measuring circuit 13 to measure the equivalent impedance Z of the battery 2 corresponding to the sine wave signal of the frequency. In another embodiment, the control circuit 10 may configure the sine wave current generating circuit 11 to send sine wave signals of multiple frequencies to the battery 2, and configure the battery impedance measuring circuit 13 to measure the equivalent impedance Z. When the equivalent impedance Z is small, the control circuit 10 records the frequency of the sine wave signal. In another embodiment, the battery charging device 1 is used to charge batteries of specific specifications, and the characteristics of these batteries are similar. Therefore, the battery charging device 1 may not include the battery impedance measurement circuit 13 and related measurement steps, and the control circuit 10 sets the sine wave current generating circuit 11 to charge the battery 2 with the sine wave current Is of a preset frequency.

FIG. 3 is a schematic diagram of a battery charging method according to an embodiment of the present invention, and the battery charging method is applicable to the battery charging device 1 shown in FIG. 1. Referring to FIG. 3 and in conjunction with FIG. 1, the battery charging method 100 comprises the following steps. In step S1, the battery charging device 1 is connected to the battery 2. In step S2, the control circuit 10 sets the DC current generating circuit 12 to generate a DC current Idc to charge the battery 2. In step S3, the control circuit 10 determines whether the sine wave current generating circuit 11 should be set to generate a sine wave current Is to charge the battery 2 according to the output of the frequency generating circuit 14. In step S4, the control circuit 10 sets the sine wave current generating circuit 11 to generate the sine wave current Is of the set frequency to charge the battery 2. In each charging cycle T in which the battery charging device 1 provides the charging current Io to the battery 2, in the time period T1, the charging current Io includes the DC current Idc, and in the time period T2, the charging current Io includes the DC current Idc plus the sine wave current Is. Therefore, the minimum value of the charging current Io is the DC current Idc.

In order to make the sine wave current generating circuit 11 generate a sine wave current Is of a specific frequency to charge the battery 2, the frequency of the sine wave current Is is matched with the equivalent impedance Z of the battery 2 to achieve the best charging efficiency. In some embodiments, as shown in FIG. 4 (in conjunction with FIG. 1), the battery charging method 100a of the present case further includes step S3a, wherein the steps similar to the battery charging method 100 shown in FIG. 3 are represented by the same reference numerals and are not repeated here. In this embodiment, in step S3a, the control circuit 10 sets the battery impedance measuring circuit 13 to measure the equivalent impedance Z of the battery 2, and according to the measurement result of the battery impedance measuring circuit 13, the frequency of the sine wave current Is generated by the sine wave current generating circuit 11 is correspondingly set so that the frequency of the sine wave current Is matches the equivalent impedance Z of the battery 2 to improve the charging efficiency.

In one embodiment, step S3a may be performed only once, and in subsequent charging, the control circuit 10 sets the sine wave current generating circuit 11 to generate the sine wave current Is of the same frequency to charge the battery 2. In another embodiment, step S3a may be performed every time a preset time interval or every time a preset battery charging level changes, to cope with the change in equivalent impedance of the battery 2 due to different charging levels. In another embodiment, step S3a may also measure the equivalent impedance Z of the battery 2 each time before the control circuit 10 sets the sine wave current generating circuit 11 to generate the sine wave current Is.

The battery charging method of the aforementioned embodiment may also be combined with other steps, such as pre-charging, constant voltage charging or stopping charging, but these steps are not shown in the previous figure.

To facilitate understanding of the charging current Io mentioned in the preceding paragraph, FIG5 illustrates the waveform of the charging current of an embodiment of the present invention. In FIG5, the current value Imax represents the maximum value of the charging current Io, which is equal to the maximum value of the sine wave current Is plus the DC current Idc; the current value Imin represents the minimum value of the charging current Io, which is also equal to the DC current Idc in the charging current Io. The current value Imax is greater than the current value Imin, and the current value Imin is greater than zero, which means that the current value of the DC current Idc is greater than zero. As shown in FIG5, in the charging current Io, both the sine wave current Is and the DC current Idc can be adjusted according to different design considerations. In some embodiments, the control circuit 10 sets the sine wave current generating circuit 11 and the DC current generating circuit 12 to generate the current value and frequency of the sine wave current Is and the current value of the DC current Idc, so that the sum of the charging amount of the DC current Idc in the time period T1 (i.e., the area A1 in Figure 5) and the charging amount of the sine wave current Is in the time period T2 (i.e., the area A2 in Figure 5) remains unchanged, thereby keeping the total charging amount consistent, but having a better charging efficiency for the battery 2.

In the above embodiment, the control circuit 10 can set the sine wave current generating circuit 11 to generate a sine wave of appropriate time. For example, the sine wave current generating circuit 11 can generate a sine wave signal of sin(2*π* f * t ), where f is the sine wave frequency and t is time. Therefore, in the time period T1, the control circuit 10 can set the sine wave current generating circuit 11 to generate a sine wave or a part of a sine wave between sin(θ1) and sin(θ2) as the sine wave current Is, and charge the battery 2 with the sine wave current Is and the DC current Idc, where θ1 and θ2 are appropriate values. For example, the control circuit 10 can set the sine wave current generating circuit 11 to generate a half-sine wave between sin(0) and sin(π), a partial half-sine wave between sin(π/8) and sin(7π/8), two half-sine waves between sin(0) and sin(4*π), etc., as the sine wave current Is.

In addition, when the current values of the sine wave current Is and the DC current Idc are increased or decreased, the temperature rise of the battery 2 during the charging process will increase or decrease accordingly. However, the battery temperature rise is more sensitive to the adjustment of the peak value of the sine wave current Is. For example, compared with increasing the size of the DC current Idc, increasing the peak value of the sine wave current Is will increase the battery temperature rise by a greater margin. It can be seen that by combining the adjustable sine wave current Is and the DC current Idc, the present case has a higher degree of flexibility in adjusting the battery temperature rise, thereby improving the charging efficiency while taking into account the temperature rise of the battery 2 during the charging process.

In summary, the present invention provides a battery charging method and device, which improves charging efficiency by combining sine wave current and direct current, and can take into account the temperature rise of the battery during the charging process by adjusting the amplitude of the sine wave current and the size of the direct current. Furthermore, the charging efficiency can be further improved by adjusting the frequency of the sine wave current to match the equivalent impedance of the battery.

It should be noted that the above is only a preferred embodiment for illustrating the present invention. The present invention is not limited to the above embodiment. The scope of the present invention is determined by the scope of the attached patent application. Moreover, the present invention may be modified in various ways by a person skilled in the art, but it does not deviate from the scope of the attached patent application.

1: Battery charging device 2: Battery 10: Control circuit 11: Sine wave current generating circuit 12: DC current generating circuit 13: Battery impedance measuring circuit 14: Frequency generating circuit Io: Charging current Is: Sine wave current Idc: DC current Z: Equivalent impedance Ro: Ohm resistance Cd: Equivalent capacitance Ld: Electrode inductance Batt: Ideal battery Rcf: Resistance 100: Battery charging method S1, S2, S3, S4: Steps T: Charging cycle T1, T2: Time period 100a: Battery charging method S3a: Steps Imax, Imin: Current values A1: Area reflecting the charging amount of the charging current in time period T1 A2: The area reflecting the charging current during time period T2

FIG. 1 is a schematic diagram of a battery charging device and a battery according to an embodiment of the present invention.

FIG. 2 shows an example of an AC impedance model of battery 2.

FIG. 3 is a schematic diagram of the process of a battery charging method according to an embodiment of the present invention.

FIG. 4 is a schematic diagram of the process of a battery charging method according to another embodiment of the present invention.

Figure 5 shows the waveform of the charging current of an embodiment of the present invention.

100:Battery charging method

S1, S2, S3, S4: Steps

Claims (8)

A battery charging method, comprising: During a first period of a charging cycle, a DC current generating circuit is provided to generate a DC current, and the DC current is used as a charging current to charge a battery; and During a second period of the charging cycle, a sine wave current generating circuit is provided to generate a sine wave current, and the DC current and the sine wave current are used as the charging current to charge the battery; Wherein the minimum value of the charging current is equal to the DC current. The battery charging method as described in claim 1 further includes: setting a battery impedance measurement circuit to measure an equivalent impedance of the battery, and setting the sine wave current generating circuit to control a frequency of the sine wave current according to the equivalent impedance, so that the frequency of the sine wave current matches the equivalent impedance of the battery. A battery charging method as described in claim 1, wherein the DC current generated by the DC current generating circuit is greater than zero. A battery charging method as described in claim 1, wherein during the charging cycle, a sum of a first charging amount of the charging current in the first time period and a second charging amount of the charging current in the second time period is a constant value. A battery charging device comprises: a sine wave current generating circuit; a direct current generating circuit; and a control circuit coupled to the sine wave current generating circuit and the direct current generating circuit; wherein, in a first period of a charging cycle, the control circuit sets the direct current generating circuit to generate a direct current, and uses the direct current as a charging current to charge a battery; in a second period of the charging cycle, the control circuit sets the sine wave current generating circuit to generate a sine wave current, and uses the direct current and the sine wave current as the charging current to charge the battery; wherein the minimum value of the charging current is equal to the direct current. The battery charging device as described in claim 5 further includes a battery impedance measuring circuit, wherein the control circuit is coupled to the battery impedance measuring circuit, the control circuit sets the battery impedance measuring circuit to measure an equivalent impedance of the battery, and the control circuit sets the sine wave current generating circuit to control a frequency of the sine wave current according to the equivalent impedance so that the frequency of the sine wave current matches the equivalent impedance of the battery. A battery charging device as described in claim 5, wherein the control circuit sets the DC current generating circuit to generate a DC current greater than zero. A battery charging device as described in claim 5, wherein during the charging cycle, the control circuit sets the sine wave current generating circuit and the DC current generating circuit so that the sum of a first charging amount of the charging current in the first time period and a second charging amount of the charging current in the second time period is a constant value.

Images