TW201734493A - Battery SOH detection method and circuit thereof whereby the battery SOH is calculated based on the ohmic resistance, the charge transfer resistance and the mass transfer impedance, and is compared with the aged battery database to estimate the battery's remaining life - Google Patents

Abstract

A battery state of health (SOH) detection method and its circuit, where the DC resistance method and the AC impedance method are respectively used to calculate the internal resistance of the battery. The internal resistance includes the ohmic resistance, the charge transfer resistance, and the mass transfer impedance. When the battery is aging, the reduction of the electrode plate active material, blockage of partition plate, and aged electrolyte will all affect the battery internal resistance. As the ohmic resistance of the battery usually only has a few milliohms, so this invention adopts the DC resistance method to measure the ohmic resistance. Utilizing the dc resistance method is able to obtain the advantage of a higher accuracy of ohmic resistance. In addition, the AC impedance method is adopted to use low-frequency AC test signals to measure the charge transfer resistance and the mass transfer impedance. The battery SOH is then calculated according to the ohmic resistance, the charge transfer resistance, and the mass transfer impedance, and is compared with an aged battery database to estimate the battery's remaining life.

Description

Battery health detection method and circuit thereof

The invention belongs to a battery health detection method and a circuit thereof, and more particularly to a battery health detection method and a circuit thereof with high accuracy to estimate battery life.

The resistance that current flows through the interior of the battery is called the internal resistance of the battery. The greater the internal resistance of the battery, the greater the Joule heat generated inside the battery, which will cause the battery temperature to rise, resulting in a decrease in battery charge and discharge performance and life. Battery internal resistance is an important indicator to measure battery performance. The smaller the internal resistance, the stronger the battery discharge capacity. The greater the internal resistance, the weaker the battery discharge capacity.

Referring to the battery equivalent circuit 1 shown in Fig. 1, the battery internal resistance in the battery equivalent circuit 1 is made up of Ohmic Resistance, Charge Transfer Resistance, and Mass Transfer Impedance. Combined, in which For the internal electromotive force (Electromotive Force), For ohmic resistance, Is a charge transfer resistor, For quality transmission impedance, It is a double layer capacitor (Double Layer Capacitance) and For the battery terminal voltage.

The ohmic resistor is mainly composed of electrode resistance, electrolyte resistance, separator resistance and connection line resistance. The voltage drop caused by the ohmic resistance is proportional to the magnitude of the charge and discharge current. Once the current is interrupted, the voltage drop disappears instantaneously. During charge and discharge, the resistance of the internal ion movement of the battery is called mass transfer impedance, and the ions move by diffusion and migration. The diffusion is caused by the difference in electrolyte concentration, and the drift is caused by the difference in electrolyte concentration. Affected by the force of the electric field. When performing a chemical reaction, the resistance to charge transfer between the electrolyte and the electrode is called charge transfer impedance, and the larger the surface area of the electrode, the lower the charge transfer resistance.

In general, there are many reasons for reducing battery life, such as high current charging, large current discharge, overcharge and discharge, ambient temperature, long-term shelf life, insufficient charging, conversion of active materials into irreversible materials during charge and discharge, and electrode grid. Corrosion, electrolyte aging, and blockage of the separator.

Conventional methods for estimating battery life include the DC Resistance Method and the AC Impedance Method. Conventional DC resistance method is to use the battery output current change And voltage changes To calculate the internal resistance of the battery, that is, the change in voltage divided by the value of current change. . However, the measured internal resistance value will be related to the length of the battery discharge test duration (T). When T is less than 10 milliseconds (Milliseconds, ms), the measured internal resistance is ohmic resistance; Nearly 0.1 to 10 seconds, the measured internal resistance includes ohmic resistance and charge transfer resistance; when T is very long enough for more than a few minutes, the measured internal resistance includes ohmic resistance, charge transfer resistance and Mass transfer impedance.

In succession, the DC resistance method is a highly accurate measurement method. When the ohmic resistance of the battery is measured by the DC resistance method, only a very short measurement time is required, and usually within 10 ms, the ohmic resistance can be measured. However, when measuring the charge transfer impedance and mass transfer impedance of the battery, a longer measurement waiting time (Minutes) is required, and the longer the measurement waiting time, the larger the power consumed by the battery.

The conventional AC impedance measurement technique is to inject an AC signal into the battery. After that, observe the voltage and current changes after the battery is injected into the signal, and calculate the impedance according to the change value of the battery voltage and current. Furthermore, the AC impedance method does not consume battery power during the measurement process. Because the AC signal charges the battery for half a week, and the negative half cycle is discharged, it does not affect the battery power, making it ideal for use on an instant On-line monitoring system. At present, the battery internal resistance measuring instrument usually uses an AC signal source with a frequency of one kilohertz (Hz). At this frequency, the measured internal resistance of the battery is an ohmic resistance, according to the ohmic resistance value. Judging the battery aging. However, although this method is simple, there is a considerable degree of error, because the basis for its evaluation is only the ohmic resistance value of the electrolyte and the electric shock plate interface, which can only explain the aging phenomenon of the electrolyte and the electrode plate interface, but The aging behavior of other components of the battery is not fully explained, such as charge transfer resistance and mass transfer impedance, so that the remaining life of the battery cannot be effectively and accurately determined.

As described above, the conventional DC resistance method has a large power consumption loss when the ohmic resistance, the charge transfer resistance, and the mass transfer impedance are measured, and the conventional AC impedance method cannot effectively measure the charge transfer resistance and the quality transfer. There is a lack of impedance and it is impossible to accurately determine the lack of remaining battery life. Therefore, it is necessary to improve the measurement method of the internal resistance of the battery.

The object of the present invention is to provide an ohmic resistance of a battery measured by a DC resistance measurement method, and thereafter, an AC impedance measurement method is used and a low frequency AC test signal is used to measure a charge transfer resistance and a mass transfer impedance of the battery, and thereafter utilized simultaneously. The ohmic resistance, the charge transfer resistance, and the mass transfer impedance are used as an estimate of the remaining life of the battery, thereby obtaining a battery health detection method and a circuit thereof with high accuracy to estimate the battery life.

According to the foregoing objective, the present invention provides a battery health detection circuit including a battery unit, a capacitor, a bidirectional conversion unit, a first voltage detection unit, a current detection unit, and a control unit. Wherein, the battery unit comprises a battery. The capacitor is electrically connected to the battery. The bidirectional conversion unit is electrically connected between the battery and the capacitor. The first voltage detecting unit is connected in parallel with the battery. The current detecting unit is electrically connected between the bidirectional conversion unit and one end of the battery, and the current detecting unit is connected in series with the battery. The control unit is electrically connected to the bidirectional conversion unit, the first voltage detecting unit and the current detecting unit. The control unit comprises a DC resistance detecting module and an AC impedance detecting module. The DC resistance detecting module is electrically connected to the first voltage detecting unit and the current detecting unit. The AC impedance detecting module is electrically connected to the first voltage detecting unit and the current detecting unit.

Further, the method further includes a second voltage detecting unit connected to the capacitor, and the control unit is electrically connected to the second voltage detecting unit.

Further, further comprising an AC/DC conversion unit electrically connected to the capacitor and the control unit, and an external AC power source electrically connected to the AC/DC conversion unit, the capacitor being electrically connected to the AC/DC conversion unit The AC/DC conversion unit is electrically connected between the external AC power source and the capacitor.

Further, the control unit is set to be a wafer or a microprocessor.

Furthermore, the present invention provides a battery health detection method, which includes the following steps:

Step 1: causing a battery to be instantaneously discharged through a bidirectional conversion unit, and storing the discharge energy in a capacitor;

Step 2: Measure the instantaneous change amount of the voltage discharged by the battery and the instantaneous change amount of the current;

Step 3: dividing the instantaneous change amount of the voltage by the instantaneous change amount of the current, thereby obtaining an ohmic resistance of the battery;

Step 4: injecting an AC test signal for the low frequency signal into the battery;

Step 5: measuring the AC voltage and the AC current of the battery;

Step 6: dividing the AC voltage by the AC current, thereby obtaining an AC impedance of the battery, thereby obtaining a charge transfer resistance and a mass transfer impedance of the battery;

Step 7: Bring the ohmic resistor, the charge transfer resistor and the mass transfer impedance into a battery state of health (SOH) equation, ;among them, Represented as the initial ohmic resistance; Represented as the initial charge transfer resistance; Represented as the initial mass transfer resistance; , , Representative is a weighted value; Representing the ohmic resistor obtained in step three; Representing the charge transfer resistor obtained in step six; Representing the mass transfer impedance obtained in step 6; and step 8: determining the health of the battery through the battery health equation.

Further, between step 1 and step 3, there is further included a step of detecting whether the energy of the capacitor is depleted.

Further, between step 1 and step 3, there is further included a step of electrically connecting an external AC power source, and supplementing the energy loss on the capacitor through the external AC power source.

Further, a step is further included between the third step and the fourth step, and the energy stored in the capacitor is recharged to the battery.

Further, the frequency of the AC test signal is less than 1 Hertz (Hz).

Further, the control unit is set to be a wafer or a microprocessor.

The invention is characterized by:

1. In this case, the AC test signal of low frequency is used to measure the charge transfer resistance and the mass transfer impedance in the internal resistance of the battery, so as to improve the conventional AC impedance method and the charge transfer resistance cannot be effectively measured by using a kilohertz measurement. The quality of the impedance does not accurately determine the lack of battery life.

2. In this case, when the internal resistance of the battery is measured by the DC resistance method, the ohmic resistance is measured only for a short time, and the charge transfer resistance measured by the AC impedance method and the mass transfer impedance are used to effectively improve the conventional DC resistance method. To measure ohmic resistance, charge transfer resistance, and mass transfer impedance, there is a large loss of power consumption.

3. In this case, the ohmic resistance, charge transfer resistance and mass transfer impedance of the battery are respectively calculated by DC resistance method and AC impedance method. Thereafter, the ohmic resistance, the charge transfer resistance and the mass transfer impedance are used to bring the battery health status. The equation is used to obtain high accuracy to estimate battery life.

4. In this case, when the ohmic resistance is measured by the DC resistance method, the energy discharged from the battery is first stored to the capacitor, and when the ohmic resistance is obtained, the energy of the capacitor is recharged to the battery, so that the battery does not have the power. There will be a reduction.

The purpose, technical contents, features and effects achieved by the present invention will be more readily understood by the following description in conjunction with the accompanying drawings.

Referring to FIG. 2 , a battery health detection circuit 20 according to the present invention includes a battery unit 30 , a capacitor 31 , a bidirectional conversion unit 40 , a first voltage detecting unit 50 , and a current . The detecting unit 60 and a control unit 70. The battery unit 30 includes a battery 300. The capacitor 31 is electrically connected to the battery 300. The bidirectional conversion unit 40 is electrically connected between the battery 300 and the capacitor 31. The two ends of the conversion side of the bidirectional conversion unit 40 are electrically connected to the positive end and the negative end of the battery 300, respectively. The two ends of the other side of the battery 300 are electrically connected to the two ends of the capacitor 31. The first voltage detecting unit 50 connects the battery 300 in parallel, thereby measuring the voltage across the battery 300. The current detecting unit 60 is electrically connected between the bidirectional converting unit 40 and one end of the battery 300. The current detecting unit 60 is connected in series with the battery 30, thereby measuring the current of the battery 300. The current detecting unit 60 has a current measuring resistor (not shown) connected in series with the battery 300, and a current detector (not shown) connected in parallel with the current measuring resistor.

The control unit 70 is electrically connected to the bidirectional conversion unit 40, the first voltage detection unit 50, and the current detection unit 60. The control unit 70 includes a DC resistance detection module (not shown), and a AC impedance detection module (not shown). The DC resistance detecting module is electrically connected to the first voltage detecting unit 50 and the current detecting unit 60. The AC impedance detecting module is electrically connected to the first voltage detecting unit 50 and the current detecting unit 60.

Further, the battery health detecting circuit 20 further includes a second voltage detecting unit 80 connected to the capacitor 31, and the second voltage detecting unit 80 is electrically connected to the control unit 70. When the internal resistance measurement of the battery 300 is performed, if the second voltage detecting unit 80 detects that the energy on the capacitor 31 is depleted, the control unit 70 receives the message of the second voltage detecting unit 80 immediately. The conduction direction of the bidirectional conversion unit 40 is controlled so that the energy lost on the capacitor 31 can be filled.

The energy lost on the capacitor 31 can be selected to be charged by the internal power source through the conduction direction of the bidirectional conversion unit 40, or an external power source can be used to charge the capacitor 31. Referring to FIG. 3, another embodiment of the present invention, the battery health detecting circuit 20a further includes an AC/DC converting unit 90 electrically connected to the capacitor 31 and the control unit 70, and a The external AC power source 91 of the AC/DC conversion unit 90 is electrically connected. The capacitor 31 is electrically connected between the AC/DC conversion unit 90 and the bidirectional conversion unit 40. The AC/DC conversion unit 90 is electrically connected between the external AC power source 91 and the capacitor 31. Once the second voltage detecting unit 80 detects that the energy on the capacitor 31 is depleted, the control unit 70 receives the message of the second voltage detecting unit 80 to immediately control the AC/DC converting unit 90 to be turned on. The external AC power source 91 charges the capacitor 31 so that the energy lost on the capacitor 31 can be supplemented, whereby the power of the capacitor 31 is recharged to the battery 300 so that the power of the battery 300 is not lost.

Please refer to FIG. 4 , which is a battery health detection method 21 proposed in the present invention. The battery health detection circuit 20 shown in FIG. 2 is exemplified, but is not intended to limit the present invention. The battery health detection method 21 includes the following steps:

Step 1: The battery 300 is instantaneously discharged through the bidirectional conversion unit 40, and the discharge energy is stored in the capacitor 31. In detail, the control unit 70 controls the conduction direction of the bidirectional conversion unit 40 to cause the battery 300 to pass through the battery. The bidirectional conversion unit 40 discharges, and the capacitor 31 stores the energy discharged by the battery 300;

Step 2: Measure the instantaneous change amount of the voltage discharged by the battery 300 and the instantaneous change amount of the current; in detail, the first voltage detecting unit 50 measures the instantaneous change amount of the voltage discharged by the battery 300, and the current detecting unit 60 Measuring the instantaneous change amount of the current discharged by the battery 300;

Step 3: The momentary change of the voltage is divided by the instantaneous change of the current, thereby obtaining the ohmic resistance of the battery 300; in detail, the first voltage detecting unit 50 is electrically connected through the DC resistance detecting module. The current detecting unit 60 is electrically connected to the current detecting unit 60 to extract the instantaneous change amount of the current, and then the instantaneous voltage change amount is divided by the instantaneous change amount of the current. Thereby obtaining the ohmic resistance of the battery 300;

Step 4: Injecting an AC test signal for the low frequency signal into the battery 300; in detail, the control unit 70 controls the conduction direction of the bidirectional conversion unit 40 to inject an AC test signal for the low frequency signal into the battery 300. In a preferred embodiment, the frequency of the AC test signal is selected to be less than 1 Hertz (Hz);

Step 5: Measure the AC voltage and the AC current of the battery 300. In detail, the first voltage detecting unit 50 measures the AC voltage of the battery 300, and the current detecting unit 60 measures the AC current of the battery 300. ;

Step 6: dividing the AC voltage by the AC current, thereby obtaining the AC impedance of the battery 300, thereby obtaining the charge transfer resistance and the mass transfer impedance of the battery 300; in detail, transmitting the AC impedance detecting module The first voltage detecting unit 50 and the current detecting unit 60 are connected to the AC voltage and the AC current respectively, and then the AC voltage is divided by the AC current, thereby obtaining the AC impedance of the battery 300. Further obtaining a charge transfer resistance and a mass transfer impedance of the battery 300;

Step 7: Bring the ohmic resistor, the charge transfer resistor and the mass transfer impedance into a battery state of health (SOH) equation, (1) ; among them, Represented as the initial ohmic resistance; Represented as the initial charge transfer resistance; Represented as the initial mass transfer resistance; , , Representative is a weighted value; Representing the ohmic resistor obtained in step three; Representing the charge transfer resistor obtained in step six; Representing the mass transfer impedance obtained in step 6;

Step 8: The health status of the battery 300 is judged by the battery health equation.

More specifically, the present invention measures the ohmic resistance by using a DC resistance method. During the measurement, the control unit 70 controls the conduction direction of the bidirectional conversion unit 40 to instantaneously discharge the battery 300 through the bidirectional conversion unit 40. The capacitor 31 is stored. The energy that the battery 300 discharges. Thereafter, the instantaneous voltage change measured by the first voltage detecting unit 50 And the instantaneous change amount of current measured by the current detecting unit 60 The DC resistance detecting module transmits the program embedded in the DC resistance detecting module to calculate a ratio between the instantaneous change amount of the voltage and the instantaneous change amount of the current, thereby obtaining an ohmic resistance of the battery 300. which is . In order to improve the accuracy of the small resistance measurement, the battery 300 is instantaneously discharged with a large output current, and the battery 300 is discharged by a constant current pulse wave by controlling the bidirectional conversion unit 40, and this is The discharge electrical energy is stored on the capacitor 31.

Generally, the internal resistance of the battery is quite small, usually only a few tens of milliohms, especially the large internal resistance is lower, so it will not be easily detected. If the current of the discharge test can be increased, the relative battery output voltage change value will also increase, so the accuracy of the test will also increase. Furthermore, the closer the test discharge current is to the load current during normal use, the resulting internal resistance value. The more you can respond to the health of the battery. In addition, in order to prevent the power of the battery 300 from being reduced during the measurement, a step is further included between the third step and the fourth step, and the energy stored in the capacitor 31 is recharged to the battery 300. In the present case, when the ohmic resistance is measured by the DC resistance method, the energy discharged by the battery 300 is first stored to the capacitor 31, and when the ohmic resistance is obtained, the energy of the capacitor 31 is recharged to the battery 300, so that the battery 300 is obtained. The amount of electricity will not be reduced.

The continuation, more specifically illustrates the step of measuring the charge transfer resistance and the mass transfer impedance by the AC impedance method. In this case, the function of the capacitor 31 can not only provide energy storage for DC resistance measurement, but also can be regarded as an AC impedance method. During the measurement of the DC terminal voltage, the control unit 70 controls the conduction direction of the bidirectional conversion unit 40 to convert the DC voltage on the capacitor 31 into an AC voltage to inject the battery 300 into a low frequency signal. The AC test signal, and thereafter the AC voltage measured by the first voltage detecting unit 50 And the alternating current measured by the current detecting unit 60 Passing to the AC impedance detecting module, the AC voltage is divided by the AC current by using a program embedded in the AC impedance detecting module, thereby obtaining an AC impedance of the battery 300, thereby obtaining a charge of the battery 300. Transfer resistance and mass transfer impedance, ie . In other words, the DC energy of the capacitor 31 is converted into AC power via the bidirectional conversion unit 40, and the AC test signal is injected into the battery 300. Finally, the AC reactance detecting module of the control unit 70 is configured according to the AC voltage. And the alternating current The charge transfer resistance and the mass transfer impedance of the battery 300 are estimated to determine the health of the battery 300. In the measurement process, the AC 300 charges the battery 300 during the positive half cycle of the AC signal, and the battery 300 discharges during the negative half cycle. Therefore, the battery 300 is not affected, so it is very suitable for use in Instant On- Line monitoring.

In order to maintain the capacitor 31 at a fixed energy when measuring the internal resistance of the battery 300, a step is further included between steps 1 and 3: detecting whether the energy of the capacitor 31 is depleted. The second voltage detecting unit 80 is connected in parallel with the capacitor 31. The control unit 70 is electrically connected to the second voltage detecting unit 80. When the internal resistance measurement of the battery 300 is performed, if the second voltage detecting unit 80 detects that the energy on the capacitor 31 is depleted, the control unit 70 receives the message of the second voltage detecting unit 80. The conduction direction of the bidirectional conversion unit 40 is immediately controlled so that the energy lost on the capacitor 31 can be filled.

The energy lost on the capacitor 31 can be selected by the bidirectional conversion unit 40 to charge the capacitor 31 with an internal power source, or an external power source can be used to charge the capacitor 31. Therefore, it can be between steps 1 and 3. There is further included a step of electrically connecting the external AC power source 91, and supplementing the energy loss on the capacitor 31 through the external AC power source 91. For the actual circuit, as shown in FIG. 3, the AC/DC conversion unit 90 is electrically connected to the capacitor 31, and the external AC power source 91 is electrically connected to the AC/DC conversion unit 90. Once the second voltage detecting unit 80 detects that the energy on the capacitor 31 is depleted, the control unit 70 receives the message of the second voltage detecting unit 80 to immediately control the AC/DC converting unit 90 to be turned on. The external AC power source 91 charges the capacitor 31 so that the energy lost on the capacitor 31 can be supplemented, whereby the power of the capacitor 31 is recharged to the battery 300 so that the power of the battery 300 is not lost. The additional AC/DC conversion unit 90 and the external AC power source 91 can not only compensate for the loss energy of the capacitor 31, but also can be injected into the battery when the charge transfer resistance and the mass transfer impedance are measured by the AC impedance method. 300 of the power source of the AC test signal. In addition, detecting whether the energy of the capacitor 31 is lossy, and electrically connecting the external AC power source 91, supplementing the energy loss on the capacitor 31 through the external AC power source 91, etc., as long as the capacitor 31 is used before step four. The loss can be completed, so in practical applications, it can be completed in each step or between each step, for example, in step one or in step one and step two, and so on.

Thereafter, the ohmic resistor, the charge transfer resistor and the mass transfer impedance are brought into the battery health equation as shown in the formula (1), and compared with the battery aging database as an estimate of the remaining life of the battery. Thereby, the health of the battery 300 is judged. The closer the resulting value is to the ideal value, the better the health of the battery 300 and the longer its service life. More specifically, the denominator of the formula (1) is the measured value, the numerator is the initial value, and the ideal result value is assumed to be 100%. When the calculated value is closer to 100%, the health of the battery 300 is better. .

Further, please refer to FIG. 5 and FIG. 6 for the simulation data of the ohmic resistance measured by the DC resistance measurement method in the first step to the third step in the present case, which respectively have a capacity of 80% of the battery and the capacity 57. % battery for testing. The ohmic resistance measured by the 80% battery shown in Fig. 5 is 62 ohms, and the ohmic resistance measured by the 57% capacity battery shown in Fig. 6 is 88 ohms.

Further, please refer to Figures 7-1 to 8-2, which are simulation data of charge transfer resistance and mass transfer impedance measured by the AC impedance measurement method in steps 4 to 6 in this case. Tested with a battery with 80% capacity and 57% battery capacity. Figure 7-1 and Figure 7-2 show the capacity of 80% batteries measured at frequencies of 0.05 Hz and 0.005 Hz, respectively. The measured AC impedance is 260 milliohms, as shown in Figure 7-1. The measured AC impedance shown in Figure 7-2 is 880 milliohms. Figures 8-1 and 8-2 show a capacity of 57% of the cells and are measured at frequencies of 0.05 Hz and 0.005 Hz, respectively, wherein the measured AC impedance is 310 milliohms as shown in Figure 8-1. The measured AC impedance shown in Figure 8-2 is 1150 milliohms.

In the present invention, the AC test signal of the low frequency is used to measure the internal resistance of the battery 300, thereby obtaining the charge transfer resistance and the mass transfer impedance, so as to improve the conventional AC impedance method by using a kilohertz measurement. Effectively measuring the charge transfer resistance and mass transfer impedance, it is impossible to accurately determine the lack of remaining battery life. Moreover, when the internal resistance of the battery 300 is measured by the DC resistance method, the ohmic resistance is measured only for a small period of time, and the charge transfer resistance and the mass transfer impedance measured by the AC impedance method are combined to effectively improve the conventional DC resistance. If the ohmic resistance, charge transfer resistance and mass transfer impedance are measured, the power consumption is large. Furthermore, in the present case, the ohmic resistance, the charge transfer resistance, and the mass transfer impedance of the battery 300 are respectively calculated by the DC resistance method and the AC impedance method, and thereafter, three ohmic resistors, the charge transfer resistor, and the mass transfer impedance are simultaneously utilized. The important parameters are brought into the battery health equation (such as equation (1)). Compared with the prior art, the estimation method of the present invention can obtain the judgment of high-accuracy battery life. In addition, in the embodiment of the present invention, the ohmic resistance is measured by a DC resistance method, and then the steps of measuring the charge transfer resistance and the mass transfer impedance by using an AC impedance method are exemplified, and in practical applications, The charge transfer resistance and the mass transfer impedance are measured by an alternating current impedance method, and then the ohmic resistance is measured by a direct current resistance method, and the order is elastically adjustable.

In the embodiment of the present invention, the control unit 70 is configured as a chip or a microprocessor, and the DC power detection module and the AC impedance detection module are embedded in the control unit 70. The control unit 70 controls the program of the conduction direction of the bidirectional conversion unit 40, or the program for calculating the ohmic resistance, the charge transfer resistance and the mass transfer impedance is a very sophisticated technology, not This is the main direction of the case and will not be repeated.

In summary, the present invention can obtain the following features:

1. In this case, the AC test signal of the low frequency is used to measure the internal resistance of the battery 300, thereby obtaining the charge transfer resistance and the mass transfer impedance, so as to improve the conventional AC impedance method and the measurement cannot be effectively performed by using a kilohertz measurement. There is a charge transfer resistance and a mass transfer impedance that cannot accurately determine the lack of remaining battery life.

2. In this case, when the internal resistance of the battery 300 is measured by the DC resistance method, the ohmic resistance is measured only for a small period of time, and the charge transfer resistance measured by the AC impedance method and the mass transfer impedance are used to effectively improve the conventional DC. If the resistance method measures the ohmic resistance, the charge transfer resistance, and the mass transfer impedance, it has a large power consumption.

3. In this case, the ohmic resistance, charge transfer resistance and mass transfer impedance of the battery 300 are respectively calculated by the DC resistance method and the AC impedance method, and thereafter the ohmic resistor, the charge transfer resistor and the mass transfer impedance are simultaneously brought into the equation. In the battery health equation shown in sub-(1), high accuracy is used to estimate battery life.

4. In the present case, when the ohmic resistance is measured by the DC resistance method, the energy discharged by the battery 300 is first stored to the capacitor 31, and when the ohmic resistance is obtained, the energy of the capacitor 31 is recharged to the battery 300. There is no reduction in the amount of power of the battery 300.

The foregoing is only a preferred embodiment of the present invention, and is intended to be understood by those skilled in the art, and is not intended to limit the scope of the invention. Equivalent variations or modifications of the shapes, configurations and features described in the scope of the present application are intended to be included within the scope of the present invention.

[ study]
1‧‧‧Battery equivalent circuit
[ present invention]
20, 20a‧‧‧Battery health detection circuit
21‧‧‧Battery health detection method
30‧‧‧ battery unit
300‧‧‧Battery
31‧‧‧ Capacitance
40‧‧‧bidirectional conversion unit
50‧‧‧First voltage detection unit
60‧‧‧current detection unit
70‧‧‧Control unit
80‧‧‧Second voltage detection unit
90‧‧‧AC/DC conversion unit
91‧‧‧External AC power supply

Figure 1: A circuit diagram of a conventional battery equivalent circuit. Fig. 2 is a circuit diagram showing a first embodiment of the battery health detecting circuit of the present invention. Fig. 3 is a circuit diagram showing a second embodiment of the battery health detecting circuit of the present invention. Fig. 4 is a flow chart showing the method for detecting the health of the battery of the present invention. Fig. 5 is a schematic view showing the waveform of the ohmic resistance measured by a battery having a capacity of 80%. Fig. 6 is a schematic view showing the waveform of the ohmic resistance measured by a battery having a capacity of 57%. Figure 7-1 is a schematic diagram showing the waveform of the AC impedance measured by a battery having a capacity of 80% and measuring at 0.05 Hz. Fig. 7-2 is a waveform diagram showing the AC impedance measured by a battery having a capacity of 80% and measuring at 0.005 Hz. Fig. 8-1 is a waveform diagram showing the AC impedance measured by a battery having a capacity of 57% and measuring at 0.05 Hz. Fig. 8-2 is a waveform diagram showing the AC impedance measured by a battery having a capacity of 57% and measuring at 0.005 Hz.

20‧‧‧Battery health detection circuit

30‧‧‧ battery unit

300‧‧‧Battery

31‧‧‧ Capacitance

40‧‧‧bidirectional conversion unit

50‧‧‧First voltage detection unit

60‧‧‧current detection unit

70‧‧‧Control unit

80‧‧‧Second voltage detection unit

Claims (10)

A battery health detection circuit includes: a battery unit, the battery unit includes a battery; a capacitor electrically connected to the battery; and a bidirectional conversion unit electrically connected to the battery a first voltage detecting unit, the first voltage detecting unit is connected in parallel with the battery; a current detecting unit electrically connected between the bidirectional converting unit and the battery end, The current detecting unit is connected in series with the battery; and a control unit is electrically connected to the bidirectional conversion unit, the first voltage detecting unit and the current detecting unit, and the control unit comprises a DC resistance detecting module And an AC impedance detecting module; the DC resistance detecting module is electrically connected to the first voltage detecting unit and the current detecting unit; the AC impedance detecting module is electrically connected to the first voltage detecting Unit and the current detecting unit. The battery health detection circuit of claim 1, further comprising a second voltage detecting unit connected to the capacitor, wherein the control unit is electrically connected to the second voltage detecting unit. The battery health detection circuit of claim 2, further comprising an AC/DC conversion unit electrically connected to the capacitor and the control unit, and an external communication electrically connected to the AC/DC conversion unit. The power source is electrically connected between the AC/DC conversion unit and the bidirectional conversion unit, and the AC/DC conversion unit is electrically connected between the external AC power source and the capacitor. The battery health detection circuit of claim 1 or 2 or 3, wherein the control unit is a chip or a microprocessor. A battery health detection method includes the following steps: Step 1: Immediately discharge a battery through a bidirectional conversion unit, and store the discharge energy in a capacitor; Step 2: Measure the instantaneous change of the voltage discharged by the battery And the instantaneous change of the current; Step 3: The instantaneous change of the voltage is divided by the instantaneous change of the current, thereby obtaining the ohmic resistance of the battery; Step 4: injecting an AC test signal for the low frequency signal into the battery; Step 5 : measuring the AC voltage and the alternating current of the battery; Step 6: dividing the AC voltage by the AC current, thereby obtaining the AC impedance of the battery, thereby obtaining the charge transfer resistance and the mass transfer impedance of the battery; Step 7: The ohmic resistor, the charge transfer resistor, and the mass transfer impedance are brought into a battery state of health (SOH) equation, ;among them, Represented as the initial ohmic resistance; Represented as the initial charge transfer resistance; Represented as the initial mass transfer resistance; , , Representative is a weighted value; Representing the ohmic resistor obtained in step three; Representing the charge transfer resistor obtained in step six; Representing the mass transfer impedance obtained in step 6; and step 8: determining the health of the battery through the battery health equation. The battery health detection method of claim 5, wherein the step 1 to the third step further comprises a step of detecting whether the energy of the capacitor is depleted. The method for detecting a battery health condition according to the sixth aspect of the invention, wherein the step 1 to the step 3 further includes a step of: electrically connecting an external AC power source, and supplementing the energy of the capacitor through the external AC power source; loss. The battery health detection method according to the fifth or sixth or seventh aspect of the patent application, wherein a step is further included between the third step and the fourth step, and the energy stored in the capacitor is recharged to The battery. The method for detecting a battery health condition as described in claim 5 or 6 or 7 wherein the frequency of the AC test signal is less than 1 Hertz (Hz). The battery health detection method according to claim 5, wherein the control unit is a chip or a microprocessor.