Summary of the invention
The application a kind of cell tester of novelty is provided, it not only can measure the internal resistance of cell, can also measure other electrical quantitys, for example the voltage at electric battery two ends, particularly high voltage.Simultaneously, the described cell tester of the application has been taked high voltage and/or large current protective device, can avoid the internal resistance measurement parts to be damaged due to high voltage or large electric current, has greatly reduced the frequency of replacing overvoltage/overflow protecting element.By the application's technical scheme, the voltage measurement scope of battery meter can be extended to the even higher magnitude of voltage of 600V." high voltage " described in the application refers to the above voltage of 60V, for example voltage between 60~600V.
Aspect of the application, a kind of cell tester of measuring the internal resistance of cell that can be used in is provided, it comprises test signal loop, response sensing loop and internal resistance measurement device, and wherein said test signal loop is used for conduction test signal between described cell tester and mesuring battary; Described response sensing loop is for detection of the response signal from mesuring battary; Described internal resistance measurement device is electrically connected to described response sensing loop, obtains internal resistance of cell value with the response signal that detects based on the response sensing loop.Described cell tester also comprises tripper, and when not carrying out internal resistance of cell measurement, described tripper is in off-state, thereby makes the loop disconnection of described test signal, and described internal resistance measurement device and described response sensing loop are disconnected.In this application, the closed and disconnected of tripper can carry out automatically, also can be by operating personnel's manual switchover.
An optional embodiment according to the application, before carrying out internal resistance of cell measurement, at first determine the level value of response signal via the response sensing loop, if determined response signal levels value surpasses a threshold level, described tripper remains on off-state; If determined response signal levels value surpasses described threshold level, described tripper is closed, makes the loop connection of described test signal, and makes described internal resistance measurement device be electrically connected to described response sensing loop, measures thereby carry out the internal resistance of cell.Alternatively, the response signal levels value of determining via the response sensing loop can be the voltage at mesuring battary two ends.Described threshold level for example can be selected the 70V magnitude of voltage.
Alternatively, internal resistance measurement device described in the described cell tester of the application can be configured to measure the internal resistance of cell according to ac-current inject method, perhaps also can be configured to according to the direct-current discharge method, the internal resistance of cell be measured.When measuring internal resistance according to ac-current inject method, incoming transport current source in described test signal loop is used for injecting ac current signal via the test signal loop to mesuring battary the two poles of the earth.Differently with it be, when carrying out internal resistance measurement according to the direct-current discharge method, access test load in described test signal loop so that mesuring battary output discharge current via the test signal loop stream through this test load.
According to the application's an optional embodiment, the tripper that is arranged in described test signal loop and/or response sensing loop is realized by relay.For example, can in described test signal loop and described response sensing loop, a relay be set respectively, to realize the function of described tripper.In addition, test signal loop and response sensing loop also can share one and singly throw two keys relay as tripper, to control simultaneously the on/off of test signal loop and response sensing loop.As an alternative, for example when measuring the internal resistance of cell according to ac-current inject method, make described electric resistance measuring apparatus disconnect also and can realize by the capacitance that is arranged in the response sensing loop from the response sensing loop.
In the application on the other hand, the described cell tester of the application also can comprise for the measurement mechanism of carrying out other electric parameter measurement functions except the internal resistance of cell is measured, thereby consist of multifunctional tester.For example, can measure with same cell tester the voltage at mesuring battary two ends.Again for example, this cell tester can carry out the function conversion between multimeter and electric battery test.
According to the application's an optional embodiment, when described cell tester was carried out other electric parameter measurement functions except internal resistance of cell measurement, described tripper was in off-state.
The described tripper of high electrical breakdown for fear of the electric battery two ends; cause the damage of internal resistance of cell measurement component; an embodiment according to the application; be provided with the first over-pressure safety device (being high pressure protector) in described test signal loop and/or response sensing loop, be used for providing overvoltage protection for described tripper when described tripper is in off-state.Optionally, the specified protection magnitude of voltage of described the first over-pressure safety device is 600V.
Another embodiment according to the application; can be provided with the first overcurrent protective device (being large current protective device) in described test signal loop and/or described response sensing loop, be used for providing overcurrent protection for described tripper when described tripper is in off-state.For example, can select rated current is that the fuse of 440mA is as the first overcurrent protective device.
In order to provide protection for internal resistance of cell measurement component when carrying out internal resistance of cell measurement; an optional embodiment according to the application; be provided with the second over-pressure safety device (being low-voltage protection device) in described test signal loop and/or described response sensing loop, be used for providing overvoltage protection when described tripper is in closure state.For example, the specified protection magnitude of voltage of described the second over-pressure safety device can be 70V.
Another embodiment according to the application; can be provided with the second overcurrent protective device (being little current protective device) in described test signal loop and/or described response sensing loop, be used for providing overcurrent protection when described tripper is in closure state.For example, can select rated current is that the current-limiting resistance of 200mA is as the second overcurrent protective device.
According to the application's an optional embodiment, the described first and/or second over-pressure safety device can be realized by gas-discharge tube, solid discharging tube, transient voltage killer tube (TVS pipe), diode array, stabilivolt or voltage dependent resistor (VDR).
According to another optional embodiment of the application, the described first and/or second overcurrent protective device can be realized by posistor (PTC), fuse or current-limiting resistance.
In the application on the other hand, cell tester described here also comprises the load current measurement mechanism that is connected to described response sensing loop, is used for carrying out load current measurement function.
In the application on the other hand, cell tester described here also comprises a pair of test test pencil, and every test test pencil all can be electrically connected to described test signal loop and described response sensing loop.
In the application on the other hand, cell tester described here also comprises display device, be used for to show the reading that response signal levels that the response sensing loop detects and/or battery meter record.According to the application's an optional embodiment, when the response signal levels that detects surpassed described threshold level, described cell tester can be sent out alarm signal, and this alarm signal can be for example the visual/signal that can listen, notes in order to reminding user.
Adopt the described cell tester of the application, not only can measure accurately to the internal resistance of cell (for example can carry out internal resistance measurement by ac-current inject method or direct-current discharge method), can also carry out other measurement functions, for example measure the voltage at battery pack two ends, perhaps the sensing lead electric current.When the battery response signal that detects has exceeded the level range that the internal resistance measurement parts allow, can be with this advisory to the user, and can the internal resistance measurement function be closed by controlling tripper, thus provide protection for cell tester.Like this, just can realize that with same testing apparatus the internal resistance of cell is measured and the measurement of other battery parameters, and can not cause damage to testing apparatus.And, can further avoid the high voltage/large electric current due to the battery two ends to cause tripper breakdown, thereby the voltage measurement scope is expanded to a kilovolt order of magnitude reliably by the design of overvoltage protection and overcurrent protection.
Embodiment
Quoted the accompanying drawing as this paper ingredient in following detailed description.The illustrative embodiment that describes in detailed description, accompanying drawing and claims is not for the restriction purpose.Can also adopt other embodiment and make other changes and the spirit and the subject area that do not break away from the application.Should be appreciated that the various aspects in this explanation and illustrated the application can be arranged, replace, make up, separate and design in a lot of difference configurations, these different configurations are all implied and are included in herein.
Hereinafter, for specific embodiment is clearly described, will adopt some specific terms.Yet adopt the original idea of these terms and unrestricted the application's protection domain, the scope of these terms should extend to any equivalence that reaches roughly the same purpose with roughly the same means and replace.
Show to Fig. 1 example the overall appearance according to the application's cell tester 1.This cell tester 1 has display screen 2 and functional select switch 3, and display screen 2 can be presented to the user with visual means with the numerical value that records, and can select different measurement functions by functional select switch 3.This cell tester 1 is circumscribed with a pair of test test pencil 4A and 4B, and when battery operated parameter was tested, test test pencil 4A, 4B contacted with the positive and negative polarities of mesuring battary 5 respectively.All insert two lead-in wires in every test test pencil, to be electrically connected to respectively test signal loop and the response sensing loop of cell tester 1 inside.As shown in Figure 1, also have soft function key F1~F4 on the panel of cell tester 1, and range switch key (" RANGE "), different measurement functions and testing range selected for the user.The panel button of the cell tester 1 shown in Fig. 1 comprises that also power switch key, backlight key, multimeter/electric battery function selecting key (" DMM/String "), user arrange key (" SETUP "), reading keeps key (" HOLD ").Certainly, the cell tester 1 shown in Fig. 1 is as just example, and those of ordinary skills can arrange etc. its profile, panel layout, button and make various changes, and the purport and the protection domain that do not deviate from the application.
Fig. 2 shows according to ac-current inject method and carries out the principle schematic that the internal resistance of cell is measured.Test signal terminal SRC_Hi in Fig. 2 and SRC_Lo are used for the alternating-current measurement electric current I
SBe applied to respectively the positive and negative polarities of mesuring battary.Wherein terminal SRC_Hi is connected to ac current source via the alternating current infusion circuit, and terminal SRC_Lo is connected to earth potential.The ac current source that uses in ac-current inject method need to have enough stability, and as far as possible little waveform distortion will be arranged, and it for example can export the sine-wave current of 1kHz, 100mA.
Response sensing terminals SNS_Hi and SNS_Lo be for detection of the response signal at mesuring battary the two poles of the earth, and the electromotive force that battery the two poles of the earth for example detected respectively is V_hi and V_lo, obtains voltage responsive signal delta V=V_hi-V_lo.The sine-wave current that is injected into battery the two poles of the earth is I
S, according to Ohm law, can calculate the impedance Z of battery=Δ V/I
S, make the phase differential between ac current signal and voltage responsive signal be
Can obtain the internal resistance of mesuring battary
Due to ac current signal I
SAnd the phase differential that exists between voltage responsive signal delta V may the interferometry precision, is to improve measuring accuracy, can be to the alternating current I that injects in the internal resistance measurement device
SCarry out synchronous demodulation with the voltage responsive signal delta V that records, for example this two paths of signals can be input to an analog multiplier.
In this improving one's methods, the ac current signal I that order is injected
S=Acos ω ω t, the voltage responsive signal that records
Wherein A is ac current signal I
SMaximum amplitude, B is the maximum amplitude of voltage responsive signal delta V, ω is the frequency of the ac current signal that injects,
Be ac current signal I
SAnd the phase differential between voltage responsive signal delta V.After passing through synchronous demodulation, the signal that obtains is:
Wherein k is the amplification coefficient of analog multiplier.After passing through low-pass filtering again, filter out AC compounent ω, obtain:
Due to the internal resistance of cell
With 2 substitutions of top equation, obtain:
R=2u/ (kA
2) (equation 3)
Parameter k in
known equation 3, A by recording and treated signal u, just can calculate simply the resistance of mesuring battary, and it are poor to have got rid of phase of ac signal
Interference.Above-mentioned computation process can be completed by the micro-control unit in the internal resistance measurement device.
Fig. 3 shows the exemplary circuit diagram according to an embodiment of the application's cell tester.As shown in Figure 3, be provided with the relay K A1 as tripper in the test signal loop, simultaneously, also be provided with the relay K A2 as tripper in the response sensing loop.In this embodiment, when described cell tester was carried out other measurement functions except internal resistance of cell measurement, when for example measuring the voltage at electric battery two ends, these two relay K A1, KA2 can all remain open.The electrical parameter values that records for example can be shown to the user by display screen shown in Figure 12.
In the time will carrying out internal resistance of cell measurement, relay K A1, KA2 all are in off-state before measurement.If the response voltage value that records has surpassed a predefined threshold voltage, 70V for example, relay K A1, KA2 still remain open, the battery response voltage value Δ V that cell tester can detect response sensing terminals SNS_Hi and SNS_Lo is shown to the user, perhaps provides an alarm signal to the user; If the response voltage value that records does not surpass this threshold voltage, can control KA1, KA2 and make its closure, this moment, the ac current signal that produces of ac current source was injected into mesuring battary via the test signal loop, the battery response voltage that is detected by response sensing terminals SNS_Hi and SNS_Lo simultaneously is sent to the internal resistance measurement device via the response sensing loop, to calculate the internal resistance of cell according to the front with reference to the described method of Fig. 2, the resistance that calculates also can be shown to the user by display screen.Optionally, after above-mentioned internal resistance measurement was completed, relay K A1, KA2 can be disconnected again, thereby ready for measure next time.Alternatively, two relay K A1, KA2 in Fig. 2 also can singly throw two keys relay by one and realize.
The switch of relay K A1, KA2 can be realized automatically, for example automatically produces a trigger pip when the response voltage that detects reaches threshold value, makes the actuating of relay; Perhaps, also can be by operating personnel for example according to the reading manual operation that shows screen display.
As another replacement scheme, the relay K A2 in the response sensing loop also can substitute with capacitance.When the relay K A1 in the test signal loop is disconnected, owing to injecting without alternating current, response sensing terminals SNS_Hi and SNS_Lo only detect the DC voltage at mesuring battary two ends, and capacitance forms DC interruption in the response sensing loop, thereby the internal resistance measurement device is kept apart; When relay K A1 was closed, owing to there being alternating current to inject, capacitance was exchanged conducting, thereby the internal resistance measurement device is linked in the response sensing loop.
In Fig. 3, the voltage responsive signal that response sensing terminals SNS_Hi detects can be sent to voltage measuring apparatus by divider resistance Rdiv 1 and Rdiv 2 and carry out voltage measurement.For example, the battery meter according to the application can provide 0~6V, 6~60V, 60~600V tertiary voltage to measure range.If the resistance of divider resistance Rdiv 1 is chosen as 10M Ω, under 0~6V range, the resistance of divider resistance Rdiv 2 is chosen as 1M Ω, thereby 6V voltage can be divided to 0.6V; Under 6~60V range, the resistance of divider resistance Rdiv 2 is chosen as 100k Ω, thereby 60V voltage can be divided to 0.6V; Under 60~600V range, the resistance of divider resistance Rdiv 2 is chosen as 10k Ω, thereby 600V voltage can be divided to 0.6V.Certainly, the application also can select the different configuration of voltage range divider resistance and divider resistance value according to different applicable cases.Under above-mentioned 60~600V range, the voltage of measurement belongs to " high voltage " on the application's meaning, and tripper is disconnected, and closes the internal resistance measurement function, otherwise may make the internal resistance measurement parts cause damage.
In addition, in order to provide overvoltage/overcurrent protection to cell tester, in the embodiment shown in fig. 3, be provided with respectively two-stage over-pressure safety device and overcurrent protective device in test signal loop and response sensing loop.Wherein first order over-pressure safety device and overcurrent protective device are used for providing protection when tripper (relay K A1, KA2) disconnects; because battery pack to be measured often has very high voltage (for example arriving 600V for 400V), the design nominal parameter of first order over-pressure safety device and overcurrent protective device should tolerate higher voltage and current value.
As shown in Figure 3; in the test signal loop; the rated withstand voltage of first order over-pressure safety device DT1 is for example 600V, and it can be realized with gas-discharge tube, solid discharging tube, transient voltage killer tube (TVS pipe), diode array, stabilivolt or voltage dependent resistor (VDR).First order overcurrent protective device for example realizes by fuse Rf, the design load current value of fuse Rf for example for 440mA, can tolerate the high pressure of 600V.When the voltage that is applied to the test signal loop surpassed 600V, first order over-pressure safety device DT1 action conducted to earth potential with high voltage, thereby provides overvoltage protection to relay K A1.Similarly, when the electric current that is applied to the test signal loop surpasses 440mA, fuse Rf will be blown, and formation is opened circuit, thereby provide overcurrent protection for relay K A1.
In response sensing loop shown in Figure 3, the over-pressure safety device DT1 in the design of first order over-pressure safety device DT2 and test signal loop is similar, and its rated withstand voltage is also 600V.And first order overcurrent protective device is realized by a posistor PTC and a resistance in series Rt, and the resistance of posistor PTC is for example 1.1k Ω here, and the resistance of resistance in series Rt is that 1k Ω, rated power are 3W.Certainly, resistance in series Rt also can select different resistances and rated power, even can be omitted.The posistor PTC of response in sensing loop also can with the test signal loop in fuse exchange; and do not affect the overcurrent protection function that the application will realize; but when posistor PTC is used in the alternating current infusion circuit, should select less resistance.
In order to provide further protection when tripper is closed, as shown in Figure 3, also be respectively arranged with second level over-pressure safety device in test signal loop and response sensing loop, and be provided with second level overcurrent protective device in the test signal loop.
Second level over-pressure safety device in test signal loop and response sensing loop can be identical or similar, and for example its rated withstand voltage is 70V.The second level over-pressure safety device here also can be realized by gas-discharge tube, solid discharging tube, transient voltage killer tube (TVS pipe), diode array, stabilivolt or voltage dependent resistor (VDR).When relay K A1, KA2 closure are measured to carry out the internal resistance of cell; surpassed 70V if be applied to the voltage of test signal loop and response sensing loop; second level over-pressure safety device will move, thereby provide overvoltage protection for ac current source and internal resistance measurement device.
Second level overcurrent protective device in the test signal loop also can realize by fuse or PTC, and its specified withstand current is for example 200mA, and being used for provides overcurrent protection for ac current source when relay K A1 is closed.Although not shown in Fig. 3, it will be understood by those skilled in the art that in the response sensing loop similar second level overcurrent protective device also can be set, thereby provide overcurrent protection for the internal resistance measurement device when relay K A2 is closed.
Also show the load current measurement mechanism that is connected to the response sensing loop in Fig. 3, be used for the load current of measuring circuit when carrying out internal resistance measurement.
Fig. 4 shows another embodiment of the application, and it has adopted the direct-current discharge method to carry out internal resistance measurement.As shown in Figure 4, be provided with test load R in the test signal loop
LFlow through this test load R from the DC current of the anodal output of mesuring battary via test signal terminal SRC_Hi
L, and flow back to the negative pole of mesuring battary from test signal terminal SRC_Lo.By controlling the break-make in test signal loop, can make the DC current of mesuring battary input form square wave, and convection current load R after tested
LMeasuring current Is measure.Mesuring battary two electrode potentials that order response sensing terminals SNS_Hi and SNS_Lo detect are respectively V_hi and V_lo, obtain voltage responsive signal delta V=V_hi-V_lo.After measuring current Is and voltage responsive signal delta V are carried out mould/number conversion respectively, it is delivered to microcontroller.Can calculate the impedance Z of mesuring battary=Δ V/I according to Ohm law in microcontroller
L
Can adopt the exemplary circuit close with Fig. 3 to realize direct-current discharge method measurement internal resistance shown in Figure 4.For example realize equally the function of tripper by relay, realizing the switching of internal resistance measurement function and other parameter measurement functions, and provide two-stage overvoltage protection and overcurrent protection to realize protection to measuring circuit.Difference is, uses test resistance I
LCome the ac current source in the test signal loop in alternate figures 3, and the on/off in test signal loop is controlled, to form the square wave testing electric current.
Although disclose the application's various aspects and embodiment at this, other aspects and embodiment are also apparent to those skilled in the art.Various aspects disclosed herein and embodiment only are used for illustration purpose, and unrestricted purpose.The application's protection domain and spirit are determined by accompanying claims.