CN100523855C - Method and device for monitoring accumulator property using transient DC small current electric quantity comparison method - Google Patents

Abstract

The invention discloses a new method for testing the internal resistance of storage batteries, and a device for testing the internal resistance, voltage and temperature of each storage battery in real time and on-line by using the new method. The uniqueness of this new method is that when testing the internal resistance of the storage battery, the transient DC small current electric quantity comparison method is used. The basic principle is to make the transient DC small current pass through the battery to be tested and the comparison resistor connected in series with it, measure the power consumption of this small current on the equivalent internal resistance of the battery and the comparison resistance, and compare the internal resistance of the battery. When the device using this new method is used to test the internal resistance of the battery, its anti-interference, repeatability, real-time and safety have reached the leading level in this field, which is beyond the reach of other methods such as the existing high-current discharge method and AC injection method. comparable. The digital transmission and the modular structure make the test system based on the device of the present invention very flexible and easy to expand functions.

Description

Method and device for monitoring battery performance by transient direct current small current electricity comparison method

technical field

The invention relates to the field of battery performance monitoring, in particular, it can monitor the internal resistance (and thus estimate the remaining capacity), voltage and temperature of the battery.

technical background

With the development of science and technology, the application of batteries in various fields has become more and more common, and its importance has become increasingly apparent. However, failures and accidents caused by battery problems also occur frequently, and some accidents are even catastrophic. The ability to diagnose the performance and health of the battery in real time and online for timely processing will be a necessary prerequisite for avoiding faults and accidents.

The previously used method of measuring the battery terminal voltage cannot truly reflect the performance and health of the battery. Only by comprehensively testing and analyzing the internal resistance, voltage, temperature and other parameters of the battery can a more scientific judgment be made on the state of the battery. The most important and most difficult of these is to be able to reliably measure the internal resistance of the battery.

The methods of measuring the internal resistance of batteries that have been applied so far can be classified into two types. One is a large current discharge method, such as the method adopted by the Alber Company of the United States, which is to discharge the battery for 3.25 seconds with a high current of 30 to 70 amperes, and measure the change of the battery terminal voltage before and after discharge to calculate the internal resistance of the battery (see patent U.S. Patent No. 5,744,962—instantaneous large current discharge to measure the internal resistance); the other is the AC injection method, which is to inject an AC signal of a certain frequency into the battery, and measure the response of the AC signal at the positive and negative terminals of the battery to calculate the internal resistance of the battery (for example Patent ZL200520133538.6 - On-line monitoring system for battery internal resistance and deterioration status). Some devices currently available for monitoring the internal resistance of batteries all imitate these two methods or apply them in a flexible way.

The above two methods have their own characteristics, but their disadvantages are also obvious: the large current discharge method needs to discharge tens of amperes for several seconds when measuring the internal resistance. It may have adverse effects on sensitive electric devices using the battery (such as microcomputer protection systems, information systems, etc.). Therefore, the manufacturer of the battery internal resistance monitoring system using this method recommends testing once a month. Such a long test interval is very poor in real-time; although the AC injection method injects a small current, the response of the AC signal on the battery is affected by the equivalent reactance of the battery, and even for the same specification of the battery, different brands and different manufacturers The products have different equivalent reactance values, which will inevitably affect the authenticity of the measured internal resistance value, and the AC injection method is also easily affected by the ripple or other random interference of the charging device.

The common point of the above two methods is that they all measure the transient voltage signal from the electrode terminal of the battery, and this voltage signal is very small, and various random disturbances can easily affect the test results.

Contents of the invention

In order to overcome the shortcomings of the above-mentioned testing method, the present invention provides a method and device for testing the internal resistance of a storage battery by adopting a transient direct current small current electric quantity comparison method. When using this device to test the internal resistance of the battery, since the DC signal of milliamp/millisecond level is applied to the battery, and the power comparison method is used, it not only overcomes the shortcomings of the high-current discharge method that has a strong impact on the battery and poor real-time performance, but also The shortcoming that the AC injection method is easily affected by various factors is overcome. It can conduct a test with a very short time interval (up to several seconds if necessary), not only has strong real-time performance, but also has good anti-interference (>70db) and high repeatability (error <1%).

The technical scheme adopted in the present invention is: under the control of the microprocessor, according to a certain time interval (several seconds to several hours), the storage battery to be tested and the contrast resistance connected in series with it pass through hundreds of milliamps and last for tens of milliseconds, synchronously Calculate the power consumption of this current on the internal resistance of the battery and the comparison resistor connected in series with it. According to the electrotechnical principle, the power consumption of the same current on the internal resistance of the battery and the power consumption on the series comparison resistance are strictly related to their resistance values. According to the corresponding relationship, the internal resistance of the battery can be calculated.

After the internal resistance of the battery is measured, the battery's health status can be determined according to the internal resistance characteristic curve of the battery provided by the battery manufacturer, and the remaining capacity of the battery can be estimated.

The device of the invention is a comprehensive modularized electronic device that measures, calculates and processes three parameters of internal resistance, voltage and temperature of a storage battery with a microprocessor as the core.

The module can accept the instructions of the monitoring module at the station to work, and convert the measured parameters into digital signals and transmit them to the monitoring module at the station through the data bus.

The beneficial effects of the present invention are:

1. Compared with the method of measuring internal resistance by the large current discharge method, the present invention overcomes the strong impact of the large current discharge method on the storage battery system and the adverse effects on the DC load, and can absolutely safely monitor the internal resistance of the storage battery on-line.

Since the battery to be tested is a short-time (tens of milliseconds), small current (<500mA) transient DC signal, which has no adverse effects on the battery and the DC system, so a very short time interval (as short as seconds) to test. Such real-time performance cannot be achieved by other methods.

2. Compared with the method of measuring internal resistance by the AC injection method, the present invention overcomes the shortcoming that the AC injection method is easily affected by the ripple of the charging device or other random disturbances to make the test results inaccurate; The disadvantage of the impact of the equivalent reactance of the storage battery; also overcome the disadvantage that the AC signal injected by the storage battery may have an adverse effect on the sensitive DC load.

3. Compared with other devices for on-line monitoring of storage battery performance, the present invention not only monitors the internal resistance and voltage of the storage battery online, but also simultaneously monitors the shell temperature of each storage battery. This function is very important—in practice, there are many instances in which the battery pack is paralyzed due to thermal runaway damage of the battery due to failure to detect abnormal temperature of the battery in time. However, if other devices for online monitoring of battery performance want to measure the temperature of each battery, an additional temperature measurement system needs to be constructed.

4. When the large current discharge method and the AC injection method test the internal resistance of the battery, they all measure the instantaneous voltage response signal of the excitation signal at the battery electrode terminal, and all kinds of interference signals are also instantaneous voltage signals, so the measurement results are resistant to Noise and repeat accuracy etc. are affected. However, when the present invention tests the internal resistance of the storage battery, it compares the electric power consumed at the same time when the transient direct current small current flows through the known resistance and the internal resistance of the storage battery. Both theory and practice have proved that this method can effectively avoid various This kind of instantaneous interference makes the invention have strong anti-interference performance (>70db) and high repeatability (error<1%) when testing internal resistance. Such excellent performance enables the device of the invention not only to monitor the internal resistance of the storage battery when the storage battery is off-line or in the state of floating charge, but also to monitor the internal resistance of the storage battery on-line when the charging and discharging current of the storage battery changes. Other devices for online monitoring of battery performance cannot do this.

5. Since the device of the present invention converts the measured battery internal resistance, voltage, and temperature analog values into digital signals for transmission, it can be considered as error-free transmission, which ensures the accuracy and reliability of the test parameters. However, other devices for on-line monitoring of battery performance transmit analog signals through a long line of several meters to tens of meters, and the test parameters are easily affected by various factors and cause errors.

6. Since the device of the present invention is a functional module that can measure, calculate, and process the internal resistance, voltage, and temperature of the storage battery with a microprocessor as the core, and converts the analog signal into data transmission, Therefore, this module can not only form a subsystem that can test multiple batteries (multiple subsystems can also form a network), but also can only use this module to test a single battery.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Figure 1 is a schematic diagram of the transient current path.

Figure 2 is a schematic diagram of the transient current and its response waveform in the storage battery and the contrast resistance.

Fig. 3 is a schematic block diagram of battery internal resistance, voltage and temperature test module (VRTM).

Fig. 4 is a schematic structural diagram of a system for testing multiple storage batteries.

Detailed ways

Fig. 1 shows the path of the transient current when the device of the present invention tests the internal resistance of the accumulator. According to electrotechnical principles, the current flowing through the internal resistance of the battery to be tested and the comparative resistance in this path are equal. When the same current passes through two different resistors, the response of the current on the two resistors (such as voltage drop) and the power consumption are strictly corresponding to the resistance values of the two resistors. This principle is the theoretical basis for testing the battery internal resistance in the present invention.

Figure 2A shows the waveform of the transient current flowing through the path shown in Figure 1, Figure 2B shows the response waveform of the transient current passing through the storage battery, and Figure 2C shows the response waveform of the current passing through the comparison resistor. The hatched parts in Fig. 2B and Fig. 2C indicate the power consumption when the transient current passes through the internal resistance of the battery and the comparative resistance in the present invention when testing the internal resistance of the battery. This principle is explained below through the mathematical relationship.

set up:

I is the transient DC current value in the path (I is a constant and I>0);

T ₁ is the initial moment of transient current (T ₁ ≥ 0);

T ₂ is the termination moment of transient current (T ₂ >T ₁ );

_R1 is the equivalent internal resistance of the battery to be tested;

_R2 is the resistance value of the contrast resistor;

u ₁ (t) is the response voltage of I on R ₁ at time t (t∈[T ₁ , T ₂ ]);

u ₂ (t) is the response voltage of I on R ₂ at time t (t∈[T ₁ , T ₂ ]);

Q ₁ is the power consumption of I on R ₁ within T ₁ ~ T ₂ ;

Q ₂ is the power consumption of I on R ₂ during T ₁ -T ₂ .

but:

${\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="Q"\; filenames="C200710200574E00111.png,C200710200574E00122.png"\; state="\{\{state\}\}">Q</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; \&Integral;</span>}_{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}^{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="R"\; filenames="C200710200574E00111.png,C200710200574E00122.png"\; state="\{\{state\}\}">R</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; I</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; dt</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

${\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="Q"\; filenames="C200710200574E00111.png,C200710200574E00112.png"\; state="\{\{state\}\}">Q</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; \&Integral;</span>}_{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}^{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="R"\; filenames="C200710200574E00111.png,C200710200574E00112.png"\; state="\{\{state\}\}">R</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; I</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; dt</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

Since the transient current passing through _R1 and _R2 at time t is the same current I(t), it can be obtained from equations (1) and (2):

$\frac{{\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="Q"\; filenames="C200710200574E00111.png,C200710200574E00112.png"\; state="\{\{state\}\}">Q</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; =</span>\frac{{<span\; class="notranslate">\; \&Integral;</span>}_{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}^{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="R"\; filenames="C200710200574E00111.png,C200710200574E00122.png"\; state="\{\{state\}\}">R</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; I</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; dt</span>}}{{<span\; class="notranslate">\; \&Integral;</span>}_{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}^{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="R"\; filenames="C200710200574E00111.png,C200710200574E00112.png"\; state="\{\{state\}\}">R</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; I</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="R"\; filenames="C200710200574E00111.png,C200710200574E00112.png"\; state="\{\{state\}\}">R</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}$

Equation (3) shows that the electricity consumed by the transient current on the battery equivalent internal resistance R ₁ and the comparative resistance R ₂ is proportional to the resistance of these two resistances.

In addition, Q ₁ and Q ₂ can satisfy:

${\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="Q"\; filenames="C200710200574E00111.png,C200710200574E00122.png"\; state="\{\{state\}\}">Q</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; \&Integral;</span>}_{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}^{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}\mathrm{<span\; class="notranslate">\; I</span>}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; dt</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

${\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="Q"\; filenames="C200710200574E00111.png,C200710200574E00112.png"\; state="\{\{state\}\}">Q</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; \&Integral;</span>}_{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}^{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}\mathrm{<span\; class="notranslate">\; I</span>}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; dt</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; )</span>$

Since the excitation current of the response voltage u ₁ (t) and u ₂ (t) at time t is the same current I(t), therefore, from equations (4) and (5), it can be obtained:

$\frac{{\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="Q"\; filenames="C200710200574E00111.png,C200710200574E00112.png"\; state="\{\{state\}\}">Q</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; =</span>\frac{{<span\; class="notranslate">\; \&Integral;</span>}_{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}^{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}\mathrm{<span\; class="notranslate">\; I</span>}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; dt</span>}}{{<span\; class="notranslate">\; \&Integral;</span>}_{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}^{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}\mathrm{<span\; class="notranslate">\; I</span>}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; =</span>\frac{{<span\; class="notranslate">\; \&Integral;</span>}_{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}^{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; dt</span>}}{{<span\; class="notranslate">\; \&Integral;</span>}_{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}^{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 6</span>}<span\; class="notranslate">\; )</span>$

Then it can be obtained from formula (3):

${\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="R"\; filenames="C200710200574E00111.png,C200710200574E00122.png"\; state="\{\{state\}\}">R</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="R"\; filenames="C200710200574E00111.png,C200710200574E00112.png"\; state="\{\{state\}\}">R</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\frac{{<span\; class="notranslate">\; \&Integral;</span>}_{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}^{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; dt</span>}}{{<span\; class="notranslate">\; \&Integral;</span>}_{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}^{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 7</span>}<span\; class="notranslate">\; )</span>$

就可最终求得待测蓄电池的等效内阻R₁。Equation (7) shows that there is a linear correspondence between the equivalent internal resistance of the battery to be tested and the comparative resistance. It is known that the resistance value of the comparative resistor _R2 is fixed and can be regarded as a constant. Therefore, as long as we can try to measure Instantaneous response voltage u ₁ (t), u ₂ (t) at time, and then use the microprocessor in the device of the present invention to calculate

The equivalent internal resistance R ₁ of the storage battery to be tested can finally be obtained.

As for the change of the signal value caused by band-pass filtering and amplification and shaping (see Fig. 3) after the storage battery response signal is sampled in the device of the present invention, the calibration of the equivalent internal resistance _R1 can be replaced by a standard resistance process to obtain the correction factor.

By (7) formula also can explain several important differences of the present invention in the transient direct current small current electric quantity comparison method that adopts when testing accumulator internal resistance and other methods such as existing large current discharge method and alternating current injection method:

1. The difference between instantaneous value and integral value

In other existing methods, when testing the internal resistance of the battery, the instantaneous voltage value of the response of the excitation current (DC or AC) on the equivalent internal resistance of the battery is measured for calculation, and the instantaneous voltage value may have singular points, and various Random interference signals also appear in the form of instantaneous voltage, which adversely affects the repeatability and anti-interference performance of internal resistance testing.

The method adopted in the present invention is to integrate the response voltage signal of the transient current on the equivalent internal resistance of the storage battery within the time period T ₁ -T ₂ and then calculate it. Because the pulse width of the instantaneous pulse voltage caused by various random disturbances is generally very narrow, and its integral value is also very small, which can be ignored relative to the integral value of the continuous signal, so the method of the present invention has a high repeatability when testing the internal resistance of the storage battery. (error less than 1%), strong anti-interference (better than 70db).

2. The difference between dynamic comparison parameters and fixed comparison parameters

In other existing methods, when testing the internal resistance of the battery, the measured excitation current (DC or AC) responds to the instantaneous voltage value change (set as ΔU) on the internal resistance of the battery and the preset "constant current" The current value (set as I ₀ ) is compared (internal resistance value ∝ΔU/I ₀ ) to obtain the internal resistance of the battery. The so-called "constant current" (I ₀ ) is relatively dynamic, and will change under the influence of various factors (such as ambient temperature, performance changes of components in the current control circuit, etc.) during long-term operation. Obviously, as long as I ₀ changes, the value of ΔU/I ₀ , that is, the calculated equivalent internal resistance of the battery will change accordingly. But this change is not a change in the performance of the battery, which affects the accuracy of the internal resistance test of the battery.

The method adopted in the present invention is to compare the integral value of the response voltage with the resistance _R2 of the fixed contrast resistor to obtain the internal resistance of the storage battery, see formula (7). Even if the transient current I changes, it has no effect on the test results because it does not participate in the calculation.

As for the fixed resistor R ₂ , the resistance value of the selected precision resistor changes only a few parts per million for a long time. This has just ensured the accuracy of the method of the present invention for testing the internal resistance of the accumulator.

To sum up, the testing method and device adopted in the present invention are the new ones with the best real-time performance, the safest for DC power supply systems, the highest repeatability, the strongest anti-interference performance, and the best stability in the field of battery testing so far. A generation of test fixtures.

If the device can be popularized and applied, it will have important social and economic benefits in various fields where storage batteries are applied.

The following describes how the device of the present invention realizes testing of the performance of each storage battery with reference to FIG. 3 .

1 shown in Figure 3 is the storage battery to be tested. When testing its internal resistance, the current control circuit 3 controlled by the microprocessor 16 and the comparison resistor 2 connected in series with it generate an excitation current (see the amplitude of the current and the transient period. Fig. 2A), this electric current will produce response signal on the internal resistance of storage battery 1 to be tested and contrast resistance 2; Filter circuit 7 to filter out all kinds of AC interference components, then send to amplification and shaping circuit 8 to sort out suitable signals suitable for A/D conversion circuit 9, and convert them into digital signals and send them to microprocessor 16 for processing; The response signal that produces is sent to A/D conversion circuit 14 after being collected by comparison resistance response signal sampling circuit 13 and is converted into digital signal and sent to microprocessor 16 to be processed; Microprocessor 16 will receive A/D conversion circuit 9 and The digital signal sent by the A/D conversion circuit 14 is temporarily stored after comprehensive operation processing.

When testing the voltage of the battery 1 to be tested, the voltage signal obtained by the voltage dividing circuit 10 is collected by the battery voltage sampling circuit 11 and then sent to the A/D conversion circuit 12 to be converted into a digital signal and sent to the microprocessor 16 for temporary storage.

When the temperature of the battery to be tested is tested, the temperature sensor attached to the battery casing converts the measured temperature into an electrical signal, which is converted into a digital signal by the A/D converter 5 and sent to the microprocessor 16 for temporary storage.

After the internal resistance, voltage and temperature of the battery to be tested are all tested, the performance test of a single battery is completed.

The process of testing the storage battery pack composed of multiple storage batteries by the device of the present invention will be described below in conjunction with FIG. 4 .

In Fig. 4, E ₁ ~ E _n are the battery cells in the storage battery pack, VRTM ₁ ~ VRTM _n are battery internal resistance, voltage, temperature test modules (VRTM) shown in Fig. 3 of the present invention, and BCM is for all VRTM modules Unified management of the station-side monitoring module, the data bus is the channel for data transmission in the entire system.

After the system is powered on and starts to run, the BCM will issue a test command to all VRTM modules, and all VRTM modules will test the internal resistance, voltage, and temperature of each battery from E ₁ to E _n and store the data temporarily (test principle described in this manual). Then the BCM module will sequentially collect the test data temporarily stored in each VRTM according to the preset address corresponding to each battery number. After receiving all the data, the BCM module will manage these data in a unified manner, display and store them, and compare them with the preset values, and send out alarm messages if there is any limit violation. More than two test subsystems can be connected into a large-scale network system through the RS485 and TCP/IP data interfaces configured by the BCM module. The USB port configured by the BCM module can be used to retrieve all stored data from the U disk.

Claims (10)

【Claim 1】 The method for monitoring the performance of the storage battery by the transient direct current small current electric quantity comparison method is characterized in that the method comprises: A. Apply a DC transient current excitation with a duration of 30-80ms and a strength of 200-500mA to the battery to be tested and the comparison resistor connected in series with it; B. Measure the power consumption of the transient DC small current on the equivalent internal resistance and comparative resistance of the battery to be tested; C. Calculate the internal resistance of the storage battery to be tested by using the measured power consumption ratio and the known resistance value of the comparative resistance. 【Claim 2】 The method for monitoring the battery performance by the transient direct current small current electricity comparison method according to claim 1, characterized in that, step B also includes: the transient direct current small current on the equivalent internal resistance of the battery to be tested and on the comparative resistance The signal is sampled in response to the signal, and the sampled signal is band-pass filtered, amplified and shaped, and then converted into a digital signal through the A/D conversion circuit and sent to the microprocessor. The microprocessor comprehensively calculates and processes the received digital signal to obtain Power consumption. 【Claim 3】 The method for monitoring storage battery performance according to claim 1, characterized in that step C further comprises: comparing the measured transient DC current to the equivalent internal resistance and comparative resistance of the storage battery to be measured Calculate the internal resistance of the battery to be tested by using the power consumption on the battery, the known resistance value of the comparative resistance and the proportional coefficient set during calibration. 【Claim 4】 The method for monitoring storage battery performance according to claim 1, characterized in that the method further comprises: measuring the terminal voltage of the storage battery and the temperature of the casing, wherein the casing temperature of the storage battery is It is obtained by using a temperature sensor to measure through the copper metal body in contact with the outer shell of the battery. 【Claim 5】 The method for monitoring storage battery performance according to claim 4, wherein the calculated internal resistance of the storage battery, the measured voltage of the storage battery and the shell temperature parameters are converted into digital signals, And the digital signal is transmitted to the monitoring subsystem of the station through the RS485 bus. 【Claim 6】 The device for monitoring the performance of the storage battery by the transient direct current small current electricity comparison method is characterized in that the device includes: The battery response signal sampling circuit samples the response of the transient DC current on the equivalent internal resistance of the battery to be tested; Band-pass filtering and amplifying and shaping, filtering and amplifying and shaping the sampled signal; The A/D conversion circuit converts the filtered and shaped sampling signal into a digital signal, and transmits the digital signal to the microprocessor; The microprocessor sets the duration of the transient DC current through the software program, and measures the consumption of the transient DC current on the equivalent internal resistance and comparative resistance of the battery to be tested according to the digital signal transmitted by the A/D conversion circuit Electricity, calculate the internal resistance of the storage battery to be tested by calculating the ratio of the measured equivalent internal resistance and the power consumed by the comparative resistance to the known resistance value of the comparative resistance and the proportional coefficient set during calibration. 【Claim 7】 The device for monitoring storage battery performance according to claim 6, wherein the device further comprises: The contrast resistance response signal sampling circuit samples the response signal of the transient DC small current on the contrast resistance, and transmits the sampled signal to the A/D conversion circuit; The current control circuit generates an excitation current for the storage battery to be tested and the comparison resistor connected in series with it; The storage battery voltage measurement circuit and the temperature measurement circuit measure the terminal voltage of the storage battery and the shell temperature. 【Claim 8】 The device for monitoring storage battery performance according to claim 6, characterized in that the microprocessor is set in the storage battery internal resistance, voltage and temperature testing module VRTM, and the storage battery internal resistance, The voltage and temperature test module VRTM performs sorting, A/D conversion, data calculation, storage, and communication based on the battery internal resistance calculated by the measured electric quantity and the known resistance value, and the measured voltage and temperature signals of the battery. 【Claim 9】 The device for monitoring storage battery performance according to claim 8, wherein the storage battery internal resistance, voltage and temperature testing module VRTM uses the calculated internal resistance of the storage battery and the measured storage battery internal resistance as claimed in claim 8. The voltage and shell temperature parameters are converted into digital signals and the digital signals are transmitted to the monitoring subsystem of the station through the RS485 bus, and the monitoring subsystem is composed of n batteries or data terminals, where n>1. 【Claim 10】 The device for monitoring storage battery performance according to claim 9, wherein the station-end monitoring subsystems include a plurality of sub-systems, and the plurality of station-end monitoring subsystems are composed of local or wide-area Domain monitoring network; the transmission of the digital signal is also through the TCP/IP, GPRS or CDMA data interface in the station monitoring module BCM; the historical data and current data in the station monitoring subsystem are passed through the U disk from the station monitoring module The USB data interface configured by the BCM is used for retrieval.

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