JPH0488801A - Residual distance recorder for electric motor car - Google Patents

Abstract

PURPOSE:To detect a residual travel impossible distance easily and accurately by obtaining and previously storing the difference of a logical electromotive voltage value and battery voltage at every residual capacity at the time of specified discharge conditions and comparing said difference with the integrating value of the difference of both voltage measured. CONSTITUTION:The difference of a logical electromotive voltage value Eo and battery voltage Es at every residual capacity at a time when a battery is discharged under specified discharge conditions is acquired, and stored previously in a differential-voltage integrating set value memory 4. The voltage value of an open-circuit voltage memory 1 at a time when the battery is open-circuited and an output from a voltage measuring sensor 2 at a time when load is applied to the battery are input to the differential- voltage arithmetic means 301 of a micro-computer 3A, and differential voltage obtained is integrated by an integrating means 302. An integrated value and a value stored in the differential-voltage integrating set value memory 4 are compared by a residual- capacity integrating means 303, and residual capacity is acquired. A residual travel possible distance is obtained from a travel distance displayed by a travel-distance measuring means 5 and residual capacity by a residual travel-possible distance arithmetic means 304. Accordingly, the residual travel-possible distance can be detected accurately by a simple device.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a device that displays the remaining travel distance of an electric vehicle such as an electric vehicle, and in particular, a device that calculates the remaining capacity of the main battery of the electric vehicle. The present invention relates to a remaining odometer for an electric vehicle that digitally displays remaining drivable distance.

[Prior Art] The following methods are known as methods for determining the remaining capacity of the main battery in order to display the remaining mileage of an electric vehicle.

(2) Specific gravity detection method The remaining capacity is estimated from the specific gravity of the electrolyte determined from the buoyancy of a sensor inserted into the electrolyte and the refractive index of the electrolyte.

■ Voltage and current detection method This method detects the battery voltage and current, and estimates the remaining capacity by utilizing the fact that the voltage and current drooping characteristics of the battery increase as discharge progresses. Compared to detection methods, this method is superior in that it does not require a dedicated sensor for the battery.

(2) Current integration method The remaining capacity is estimated by subtracting the integrated value of the load current from the initial value set before using the vehicle (full charge when charging is complete). Compared to the voltage/current detection method described in , (2), the influence of temperature is reduced and accuracy is improved.

(2) Open-circuit voltage detection method This method takes advantage of the fact that the no-load open-circuit voltage of a battery changes depending on its remaining capacity.

[Problem to be solved by the invention]

The conventional remaining capacity estimation methods described above each have the following problems.

■Specific gravity detection method has relatively good accuracy, but it requires a dedicated sensor for the battery, and there are problems such as difficulty in displaying while driving due to fluctuations in the electrolyte level while driving. There is.

(2) Voltage/current detection method This method is structurally large because it is sensitive to temperature changes and requires a shunt for current detection. Furthermore, there is a problem in that adjustment is required for each rated capacity of the battery to be mounted.

(2) Current integration method If the load current fluctuates greatly, correction is required, there are problems with how to set the initial value, and a shunt resistor is required.

(2) Open-circuit voltage detection method This method is unsuitable for vehicles that operate continuously, as there are few opportunities for no-load conditions.

As described above, each of the conventional battery remaining capacity estimation methods has its own problems, and there is a problem in that it cannot be used for the purpose of displaying the remaining travel distance of an electric vehicle.

(Objective of the Invention) The present invention aims to solve the problems of the prior art as described above, and provides a method for accurately knowing the remaining capacity of a battery and thus realizing a remaining odometer for an electric vehicle. The purpose is to provide a remaining odometer for electric vehicles.

[Means to solve the problem]

In the present invention, the theoretical electromotive voltage (open circuit voltage) value E of the battery is
0 and the battery voltage (discharge voltage) Em, means for integrating the differential voltage at predetermined time intervals to obtain an integrated value, and calculating the differential voltage for each remaining capacity under predetermined discharge conditions. means for storing the set value of the integrated value; means for comparing the stored set value of the differential voltage integrated value with the measured differential voltage integrated value to determine the remaining capacity at the time of measurement; and means for determining the distance traveled since the start of travel. The system is also configured to provide a means for determining the remaining travelable distance from the remaining capacity up to the measurement time using the mileage up to the predetermined remaining capacity as a reference.

This aims to achieve the above-mentioned purpose.

[For production]

In the present invention, first, the difference voltage between the theoretical electromotive voltage value E0 of the battery and the battery voltage EII is determined, and this difference voltage is integrated at predetermined time intervals to obtain an integrated value. On the other hand, the integrated value of the difference voltage between the theoretical electromotive voltage value E0 and the battery voltage E for each remaining capacity under a predetermined discharge condition is determined and stored in advance. Then, the remaining capacity at the time of measurement is determined by comparing the stored set value of the differential voltage integrated value and the measured differential voltage integrated value, and the distance traveled since the start of driving of the vehicle is determined, and the predetermined remaining capacity is determined. Since the remaining travel distance is determined from the remaining capacity up to the measurement point based on the distance traveled up to the time of measurement, there is no need for a dedicated sensor like in the specific gravity detection method, but instead a current detection method like in the voltage/current detection method or current integration method. Since no shunt is required, the structure can be made smaller and can be used while driving.

〔Example] An embodiment of the present invention will be described below with reference to the accompanying drawings.

In FIGS. 1 and 2, reference numeral 1 indicates a battery open-circuit voltage memory, and reference numeral 2 indicates a battery voltage measurement sensor. Further, reference numeral 3 indicates a microcomputer, and reference numeral 3A indicates a microcomputer calculation section. The embodiment shown in FIGS. 1 and 2 includes a differential voltage calculation means 3° for calculating the differential voltage between the theoretical electromotive voltage value E0 of the battery and the battery voltage E, and a differential voltage calculation means 3° that calculates the differential voltage at predetermined intervals. Difference voltage integration means 3゜2 to calculate the integrated value
, a differential voltage integrated value fixed value memory 4 that stores the set value of the differential voltage integrated value for each remaining capacity under predetermined discharge conditions, and a differential voltage integrated value fixed value memory 4 that stores the set value of the stored differential voltage integrated value and separately measures it. A remaining capacity calculation means 3゜3 calculates the remaining capacity at the time of measurement by comparing the difference voltage integrated value, a running distance measuring means 5 calculates the running distance from the start of running of the vehicle, and a running distance measuring means 5 calculates the remaining capacity at the time of measurement by comparing the difference voltage integrated value. The vehicle is equipped with a remaining drivable distance calculation means 3.4 for calculating the remaining drivable distance from the remaining capacity up to the measurement time based on the distance traveled. Among these, the differential voltage calculation means 3
゜1, differential voltage integration means 3゜2, and remaining capacity calculation means 3
A microcomputer calculation section 3A is composed of the 3.degree.3 and the remaining travel distance calculation means 3.4.

To explain this in more detail, in FIG. 2, the battery electrolyte temperature (T,) detection signal 6 from the temperature detection thermistor
a is converted into an analog digital (A/D) signal via a signal amplifier 7.
) converter 9, and the main battery voltage (E, ) signal 2a from the battery voltage measurement sensor 2 equipped on the main battery passes through the signal amplifier 8 and is converted into an analog/digital (A/D) signal 2a.
) are input to the converter 9, each converted into a digital signal, and then read into the microcomputer 3. Further, a speed signal from a speed sensor 10 that detects the speed of the vehicle is read into the microcomputer 3 via a pulse correction circuit 11. Further, numeral 5 is a reset signal, numeral 12 is an LCD (liquid crystal) module, and numeral 13 is a select switch.

Calculation of battery remaining capacity in this embodiment is performed as follows.

While the electric vehicle is running, the discharge capacity of the main battery changes depending on the physical state of the battery, discharge conditions, and the like.

FIG. 3 shows an example of changes in battery voltage.

In FIG. 3, Eo indicates the theoretical electromotive voltage value, that is, the open circuit voltage. On the other hand, the voltage (discharge voltage) Em during discharge of the battery decreases in accordance with the discharge current, resulting in a voltage difference Δ■. Therefore, by determining the voltage difference Δ■, the discharge current can be determined conversely.

FIG. 4 shows the relationship between the remaining capacity and the open circuit voltage E0.

In FIG. 4, the remaining capacities of the batteries a, b, c, d, and e are 90%, 80%, 70%, and 60%.

The figure shows the value of the open circuit voltage E0 for the case of 50%. In the case of a lead-acid battery, the open circuit voltage E0 has a linear relationship with the remaining capacity, as shown in FIG.

FIG. 5 shows the relationship between remaining capacity and battery voltage.

In this FIG. 5, A indicates the open circuit voltage E0, and B indicates the discharge voltage Em.

In the diagram, a', b', c', d', and e' have remaining capacity of 9.
The voltage difference is shown for each discharge time corresponding to a 10% decrease in remaining capacity for cases of 0%, 80%, 70%, 60%, and 50%.

Therefore, the discharge amount corresponding to each remaining capacity is defined as follows.

■,. =a.

■,. =a'+b'■,. =a'+b'+c'V,,o=a'+b'+c'+d'V,
,=a'+b'+c'+d'+e'where, ■. ,■
,. ,■,. ,■,. +V%. is a combination of discharge voltage and discharge time, and a, b, c, d, and e, which show the relationship between the open circuit voltage E0 and the remaining capacity shown in Fig. 4, are the values stored in the microcomputer. , the voltage difference Δ■ is calculated by a microcomputer every 1 second, and is determined in advance by a discharge experiment under specified discharge conditions and stored in the microcomputer.

Then, the voltage difference Δ■ due to the running of the electric vehicle is measured, and the microcomputer corrects the discharge state, discharge conditions, etc.
*a, V go, V to, V bo,
Calculate remaining capacity by comparing V so .

FIG. 6 shows a routine for calculating remaining capacity.

In the figure, El is the main battery voltage (discharge voltage).

Eo is a theoretical electromotive voltage/(open circuit voltage) value, and in the case of a lead-acid battery, there is a nearly linear relationship between the remaining capacity and the theoretical electromotive voltage value E0. Also, ■Ei is the product value of the voltage difference Δ■, Vq
o, Vso, '/'+o, V2O, Vso are set values for each discharge state.

The capacity calculation routine shown in FIG. 6 is performed, for example, every IC seconds.

After determining the remaining capacity of the battery in this way, the microcomputer integrates and stores the actual travel distance of the electric vehicle from the start of travel based on the rotation speed of the travel distance sensor in the speedometer, and then calculates the constant for each discharge rate. The remaining mileage is determined and displayed digitally.

FIG. 7 is a block diagram showing a specific example of the configuration of the digital remaining odometer.

This digital remaining odometer is a device that stores the distance traveled and battery voltage in a microcomputer from the time an electric vehicle starts driving, calculates and digitally displays the distance that can be traveled according to the remaining capacity of the battery at that time. Its purpose is to inform the driver of the distance that can be traveled from now on.

As shown in FIG. 7, the digital remaining odometer 2
1 includes a distance display section 22 and a battery capacity detection calculation section 23 using an 8-bit microcomputer, a digital display section 24 for remaining mileage consisting of an LCD, and voltage (E, ) and liquid temperature (T).
, ) and a selection switch 25 for remaining mileage (Km).
RPM) 26, main battery voltage El (V) 27, and electrolyte temperature Tl (''C) 28 are read from the outside.

FIG. 8 explains the operation of the digital remaining odometer.

In the figure, the display of remaining capacity from 90% to 80% is rA)7
/1- (B-A) Displays the remaining mileage of J, and the display of remaining capacity from 80% to 70% is rB*6/2- (C
-B) Display the remaining mileage of J, remaining capacity 70% ~ 6
The display up to 0% shows the remaining mileage of rC*5/3- (D-C)J, and the display up to 60% to 50% of the remaining capacity shows r]:14/4- (E-D ) J's remaining mileage is displayed, and the display of remaining capacity from 50% to 20% is rE
*315- (F-E) The remaining mileage of the J is displayed, and it is shown that the display of the remaining capacity of 20% or less is based on the remaining mileage Ok.

However, here, A indicates the traveling distance from the start of driving until the remaining capacity is 90%, and B indicates the remaining capacity 80% from the start of driving.
%, C indicates the mileage from the start of the trip to 70% of the remaining capacity, D indicates the mileage from the start of the trip to 60% of the remaining capacity, and E indicates the remaining capacity from the start of the trip. F indicates the distance traveled up to 50%, and F indicates the distance traveled from the start of travel until the remaining capacity reaches 20%.

As shown in the figure, the digital display is 10%.

Correction is performed at each discharge state of 20%, 30%, 40%, and 50% to improve accuracy. This correction includes battery electrolyte temperature correction.

The mileage of an electric vehicle, etc. is detected from the rotation speed of the flexible shaft in the speedometer, stored in the memory of the microcomputer of the distance display section 22, and the mileage from the start of the trip is determined by the output from the capacity detection calculation section 23. As a standard, the distance that can be traveled is displayed digitally. The conversion multiplier for each capacity is set in consideration of battery life and safety so that the distance will be O when the battery reaches a depth of discharge of 80%.

The relationship between battery capacity detection and remaining mileage is displayed based on the distance traveled when the battery is discharged at 10% (remaining capacity: 90%). Considering the battery life, the value is O(
Km) is used.

When 20% of the battery capacity is consumed while driving (remaining capacity is 80%)
%) and when 30% of the battery capacity is consumed (remaining capacity 70
%) and when 40% of the battery capacity is consumed (remaining capacity 60
%) and when 20% of the battery capacity is consumed (remaining capacity 80
%) to calculate the battery capacity and mileage, respectively.
Automatically correct the displayed value of remaining mileage.

By pressing the reset button and inputting the reset signal 5a before starting the trip, all memory values (distance) can be cleared and the mileage A-F can be reset to zero.
shall be set to .

Further, the temperature correction is based on a temperature of 30° C., and the following equation holds true as the relationship between capacity and temperature.

Here, the capacity (AH) t: at Cst:t''C is converted to the pond temperature, C,3 (1: Capacity (AH) at 30°C. Temperature correction is performed based on this relationship. That is, the temperature is 40°C.
The remaining mileage display at 10% discharge is rtos*
(A*7/1)-CB-A)J. Also, the remaining mileage display when the temperature is 10°C and the discharge is 10% is rO, 9*
(Aj7/1)-(B-A)J.

[Effects of the Invention] As explained above, according to the present invention, the remaining odometer of an electric vehicle does not require a dedicated sensor for the battery and does not require a current detection shunt, so it is structurally compact. It also allows for use while driving. Furthermore, since there is no detection error in battery capacity due to temperature, accuracy is improved, and there is no need to make adjustments for each rated capacity of the battery, making stable capacity verification possible even during continuous operation. Furthermore, since the display is performed using an LCD, energy saving can be achieved.

Therefore, by applying the present invention, effects can be expected in terms of efficient operation and safety of electric vehicles, and, for example, if the distance display is set to O at a depth of discharge of 80%, it is also possible to prevent battery deterioration.

[Brief explanation of drawings]

1 and 2 are block diagrams each showing an embodiment of the present invention, FIG. 3 is a diagram showing an example of changes in battery voltage, and FIG.
Figure 5 shows the relationship between open circuit voltage E0 and remaining capacity, Figure 5 shows the relationship between battery voltage and discharge time, Figure 6 shows the remaining capacity calculation routine, and Figure 7 shows the digital residual capacity. FIG. 8 is a block diagram showing a specific example of the configuration of the mileage needle, and is a diagram explaining the operation of the digital remaining mileage meter. 3...Microcomputer, 3A...Microcomputer calculation section, 3゜,
... Differential voltage calculating means, 3.2... Differential voltage integrating means,
3.3... Remaining capacity calculating means, 3゜4... Remaining travel distance calculating means, 4... Differential voltage integration setting value memory,
5... Mileage measuring means, Eo-- theoretical electromotive voltage (open circuit voltage) value, Em'-- discharge voltage. Fig. 1 Patent applicant Suzuki Automobile Industry Co., Ltd. agent Patent attorney Isamu Takahashi] Mirror Fig. 4 (Electrical capacity and open circuit voltage) Fig. 5 Section 8 Capacity and battery voltage) Adjustment 9flυ'/[1bU 51J 2 - (Tadangi 51 keikihiki) Hinoki cypress tree 7 drawings (specific examples)

Claims (1)

[Claims] (1) means for determining the differential voltage between the theoretical electromotive voltage value E_0 of the battery and the battery voltage E_■, means for accumulating the differential voltage at predetermined time intervals to obtain an integrated value, and a residual voltage under predetermined discharge conditions. means for storing a set value of the integrated value of differential voltage for each capacity, and comparing the stored set value of the integrated differential voltage value with the measured integrated value of differential voltage to determine the remaining capacity at the time of measurement. and a means for determining the mileage from the start of travel of the vehicle, and a means for determining the remaining drivable distance from the remaining capacity up to the measurement time based on the mileage up to a predetermined remaining capacity. Remaining odometer for electric vehicles.