JP2906738B2 - Electric vehicle charging system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging system for an electric vehicle, and more particularly, to a charging system using an equal charging method in addition to a normal charging method.

[0002]

2. Description of the Related Art Electric vehicles are particularly suitable for use in indoor vehicles in that they have low noise and emit no exhaust gas, but they have the disadvantage that energy supply (that is, charging) is troublesome. is there. FIG. 5 is a power system diagram of a general electric vehicle, in which an input unit for charging a battery with a commercial power supply and an output unit for driving a motor such as a traveling motor, a cargo handling motor, and a power steering motor with a discharge current of the battery. Are roughly divided into The input unit operates while the vehicle is stopped (for example, at night) or the like, and replenishes the battery with energy lost due to cargo handling or the like.

Here, a battery of an electric vehicle is required to have conditions such as excellent vibration resistance, light weight, high weight efficiency and volumetric efficiency, and easy charging, and a lead storage battery is generally used. In particular, depending on the structure of the cathode plate, an ebonite clad type or a fiber clad type is often used. The electromotive force per cell of the lead storage battery (potential difference between electrodes measured in a state where no current flows) is 2 V, and the voltage (terminal voltage, closed circuit voltage) applied to the load is smaller than this electromotive force. In the following, the terminal voltage per cell is set to 2 V as in the case of the electromotive force for the sake of simplicity.
That is, since a 24V battery is configured by connecting 12 cells in series, a terminal voltage of 2V × 12 times = 24V can be obtained.

Various methods are known for charging a lead storage battery, such as a constant current charging method, a stepwise charging method, a constant voltage charging method, a quasi-constant voltage charging method, and the like. The charging is completed when the voltage rise (or the specific gravity rise) stops (the time point here is a time having an arbitrary width) (hereinafter, such a charging method is referred to as “normal charging”). Say).

[0005] By the way, when only normal charging is repeated, the energy stored in each cell varies, and a normal terminal voltage may not be obtained even after the charging is completed. This is due to subtle differences in the internal resistance or the agent or the electrode material of each cell, because SO ₄ in the electrolyte solution remaining in the cathode _{(Pb) (H 2 SO 4} ) is uneven.

Therefore, in order to reduce the residual SO ₄ , overcharging is performed at appropriate intervals (charging is continued for about 2 hours even after the rise of the terminal voltage stops). This operation equalizes the terminal voltage of each cell, and is called “equal charging”.
It is called. A person may determine when to perform equal charging. However, since it is necessary to correctly grasp the correct knowledge of the battery and the past charge record, it is difficult to expect such a request from a general user.

Therefore, a charging system for an electric vehicle includes:
A function for automatically determining the execution time of the uniform charging is incorporated. FIG. 6 is a block diagram of the main part, and the parameters for the determination are the number M of times of normal charging and the temperature T of the battery. Note that M _ref1 is a first reference number (for example, 10 times), and M _ref2 is a second reference number (for example, 15 times).
Times), T _ref is a reference temperature (for example, 10 degrees C).

[0008] Operational amplifier OP₁Output of a normal charge
Less than 10 times (M ≦ M_ref1) If H, 10 times or more
Upper (M> M_ref1), It becomes L. Also, the operational amplifier
OP _TwoIs output when the number of times of normal charging is 15 times or more (M>
M_ref2), H, less than 15 times (M ≦ M_ref2)
L. Furthermore, an operational amplifier OP_ThreeOutput is
Battery temperature is 10 degrees C or more (T> T_ref) If H,
Less than 10 degrees C (T ≦ T_{r ef}), It becomes L. But
So, if the number of normal charging is less than 10 times
Charging is selected, or if it is 15 times or more, equal charging
Is selected.

[0009] For 10 to 14 times,
The battery temperature at that time is added to the determination condition. That is, if the number is 10 times or more and less than 15 times, both become H, and the output of the AND gate 1 becomes H.
One of the output of the AND gate 2 and the output of the AND gate 3 becomes H in accordance with the magnitude relationship between T and T _ref at that time. Therefore, either normal charging or equal charging is selected according to the battery temperature at that time.

The above operation can be summarized as follows. 1. Past charge count M is less than 10 ... Normal charge is unconditionally selected. 2. Past charge count M is 15 times or more: Unconditional charge is selected unconditionally. 3. Past number of times of charging M is 10 times or more and less than 15 times 3-B. Battery temperature T is equal to or higher than 10 degrees C. Selects equal charging.

3-b. Battery temperature T is less than 10 degrees C ...
… Select normal charging.

[0012]

However, in such a conventional electric vehicle charging system, since only the number of past chargings is referred to as a charging history, variations in stored energy due to low-temperature charging are taken into consideration. There is a disadvantage that it is not done. That is, the variation in stored energy for each cell depends on the number of times of normal charging, and also depends on the battery temperature during charging,
Even if the number of times of charging is the same, the higher the frequency of low-temperature charging, the more likely variation will occur. Therefore, in the conventional case, since it depends only on the number of times of charging in the past, even if low-temperature charging continues, it reaches a predetermined number of times (for example, 15 times), or 10 times or more when 10 times or more. Unless it is equal to or higher than C, uniform charging cannot be performed, and there is a problem that the variation cannot be recovered at an early stage.

The present invention has been made in view of such a problem, and an object of the present invention is to add a past temperature history to a judgment material so as to appropriately determine an execution timing of a uniform charging.

[0014]

According to the present invention, in order to achieve the above object, the principle diagram is shown in FIG. 1, and in response to a predetermined charge command, the point in time when the rise of the terminal voltage stops is defined as the charge completion. The first charging operation is performed, or the second charging is completed when a predetermined time has elapsed after the rise of the terminal voltage has stopped.
A charging system for an electric vehicle that performs any one of the charging operations described above on a storage battery, wherein a temperature measurement unit that measures the temperature of the storage battery or the environmental temperature of the storage battery is provided, and the temperature measured by the temperature measurement unit is a predetermined value. A temperature determination unit that outputs a first determination signal when the temperature is equal to or more than the reference temperature, and outputs a second determination signal when the temperature is less than or less than the reference temperature. Signal generating means for generating a count signal in response to the first determination signal, and providing a first weight value to the count signal in response to the first determination signal, while providing a first weight value larger than the first weight value in response to the second determination signal Weighting means for giving a second weight value to the count signal; integrating means for integrating the weighted count value; and the integration result of the integrating means being less than or less than a predetermined reference value While outputting a charging command for instructing the first charging operation, and outputting a charging command for instructing the second charging operation when the charging command exceeds or exceeds a predetermined reference value, and calculating the integrated value of the integrating means. And a charge command / reset means for resetting.

[0015]

According to the present invention, a count signal is generated each time the first charging operation is performed, and a count signal is generated according to a magnitude relationship between the temperature of the storage battery at that time or the environmental temperature of the storage battery (hereinafter, storage battery temperature) and the reference temperature. The weighted value is given to the count value and integrated. Here, there are two types of weight values: when the storage battery temperature is higher and lower than the reference temperature.
The latter weight value (second weight value) is larger than the former.

Therefore, when the number of times of charging under low temperature is large, the integrated value immediately exceeds the reference value, so that the second charging operation can be selected according to the past temperature history.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. 2 to 4 are diagrams showing an embodiment of the charging system for an electric vehicle according to the present invention. First, the configuration will be described. In FIG. 2, reference numeral 10 denotes a three-phase input outlet connected to a commercial power supply while the electric vehicle is stopped (for example, at night);
Reference numeral 1 denotes a magnet switch for three-phase AC that is turned on in accordance with a signal S _ON from a controller 12, 13 a transformer that steps down a three-phase AC voltage to a predetermined voltage, and 14 a DC switch that performs full-wave rectification on the stepped-down three-phase AC. Rectifier for generating voltage _VDC , 15
Is a battery (storage battery). Note that a DC voltage stabilizing circuit may be added to the above configuration.

On the other hand, the controller 12 is configured to include a hard logic such as a transistor or a microcomputer, and a start signal S _C from a charge start switch 16.
, And selects either “normal charging” (corresponding to the first charging operation) or “equal charging” (corresponding to the second charging operation), and switches the magnet switch for a time set by the charging method. A signal S _ON for turning on the switch 11 is output.

The controller 12 performs the above selection.
At this time, the temperature measured by the temperature sensor (temperature measuring means) 17 is
Battery temperature T (may be battery ambient temperature)
Refer to the signal from the battery terminal voltage sensor that does not exist. Figure
3 is a case where the controller 12 has a hard logic configuration
3 is a block diagram of the main part of FIG. In this figure,
The battery temperature T is suitable for digital processing by the input circuit 20.
Converted into a first signal, and a first comparing circuit (temperature determining means) 2
At 1, the temperature is compared with the set value A (for example, A = 10 degrees C).
You. Output S of first comparison circuit 21_{twenty one}Means that the battery temperature is 10
If degree C is higher than (T> A) or exceeds (T ≧ A)
H, less than (T ≦ A) or less (T <A)
If there is, it becomes L. S_{twenty one}And inverter 22
Turned S_{twenty one}(S_21X) Means two AND gates 2
3 and 24 are provided to one of the inputs, respectively.
Input circuit 25 is connected to the other input of
Start signal from the charge start switch 16 captured through the
No. S_CIs given. Note that the charge start switch 16 and
And the input circuit 25 are normally charged (corresponding to the first charging operation)
Every time is executed, the signal S as the count signal _CGenerate
Function as the signal generating means described in the gist of the invention.
You.

[0020] That is, since the start signal S _C 1 one occurs every charging operation is a signal corresponding to the count signal described in the Summary, the signal S _C is the set value A and the battery temperature T Two AND gates 2 depending on the size relationship
Allocated to 3,24, one of the output (S ₂₃ or S ₂₄₎ only appear. Now, consider the case where the storage battery temperature T is higher than the temperature of the set value A (10 degrees C) (hereinafter, high-temperature charging). In this case, since S ₂₁ = H (S _21X = L), the signal S _C appears at the output S ₂₃ of the AND gate 23. On the other hand, consider a case where the storage battery temperature T is lower than the temperature of the set value A (10 degrees C) (hereinafter, low-temperature charging). In this case, contrary to the above, since S ₂₁ = L (S _21X = H),
Signal S _C appears at output S ₂₄ of AND gate 24.

These S_{twenty three}Or S_{twenty four}Signal S that appeared on_C
Is the first weighting circuit 26 or the second weighting circuit 27
And the set values respectively corresponding to the first weight value
B (for example, B = 2) and setting corresponding to the second weight value
A value C (for example, C = 3) is given. These first weights
The weighting circuit 26 and the second weighting circuit 27
Function as the weighting means described in the description. Below, weighted
S_{twenty three}And S _{twenty four}And S_23BAnd S_24C
Identify as S_23BOr S_24CIs or gate 28
Is taken into the integrating circuit 29 via the
Is S until the reset signal R is given._23BOr
S_24CAnd outputs the integrated value Σ. Accordingly
The integrating circuit 29 is used as an integrating means described in the gist of the invention.
Function. The integrating circuit 29 is a battery backup.
Even if the main switch is turned off, the integrated value Σ
It does not disappear. The integrated value Σ is the second comparison circuit
30 in the second comparison circuit 30.
(For example, D = 30). Second comparison circuit 30
Indicates that the integrated value Σ is less than 30 (３０ ≦ D) or less
If (Σ <D), it becomes H, and the value is 30 or more (Σ> D)
Or, if it exceeds, the signal S which becomes (Σ ≧ D) L₃₀Fill
Output to the charging method switching circuit 31 and the charging method switching circuit 3
1 is the signal S₃₀If "H", select "Normal charge"
On the other hand, if it is L, select "Equal charging, and select
A signal S that lasts for a suitable time_ONIs output. In addition,
The power method switching circuit 31 outputs the signal S₃₀Reset signal when
The signal R is output to the integrating circuit 29. Therefore, the charging method
The switching circuit 31 is provided with a charge command / reset described in the gist of the invention.
Function as a means of monitoring.

Next, the operation will be described. First, consider the case where the user charges for the first time. In this case, the integrated value Σ is, for example, zero in the reset state. Charge start switch 1
6 was to the signal S _C is generated operation, the signal S _C is distributed to one of S ₂₃ or S ₂₄ in accordance with the battery temperature T at that time. That is, if charging at high temperature, S _C = S ₂₃
Or, if charging at low temperature, S _C = S ₂₄ .
Therefore, the integrated value Σ includes the set value B for high-temperature charging.
(2) is entered, or if the battery is charged at low temperature, the set value C
(3) will be entered. In any case, since the integrated value Σ is equal to or smaller than the value (30) of the set value D, normal charging is selected.

Next, the case where the second charging is performed will be considered.
Also in this case, similarly to the above, a weight value (set value B or C) corresponding to the storage battery temperature T at that time is added to the signal S _C and added to the above integrated value Σ. Even if the larger weight value (set value C) is added during low-temperature charge, the integrated value 加 算 after the addition is equal to or smaller than the set value D, and normal charge is selected as in the first time.

Here, it will be examined how many times the charging is switched to the uniform charging when only the high-temperature charging is repeated. Since the weight value (set value B) at the time of high-temperature charging is “2” in the embodiment, it is necessary to repeat (set value D ÷ set value B) times to reach the switching level. That is, 15 repetitions are required. On the other hand, when only low-temperature charging is repeated (set value C ÷ set value D) times,
It only needs to be repeated 0 times.

The same applies to a case where high-temperature charging and low-temperature charging are performed in a mixed manner. Depending on the rate of low-temperature charging, it is possible to switch to uniform charging by the number of times within the range of less than 15 times to 10 times or more. As described above, according to the present embodiment, the storage battery temperature for each charge is left as a history along with the number of times of charging, and switching to the uniform charging is determined based on this history. In the case where the variation in the stored energy of each cell becomes large, it is possible to execute the uniform charging promptly, and it is possible to maintain the state of the storage battery in a good state and extend the battery life.

In the above-described embodiment, the hardware logic configuration has been described. However, the present invention is not limited to this, and can be realized by software. FIG. 4 is a flowchart showing an example of the operation, which is executed inside the controller 12 of FIG. The flowchart is roughly divided into a processing unit 30 before charging starts, a processing unit during charging (omitted), and a processing unit 40 after charging is completed. COUNT1 and COUNT2 in the flowchart are variables for low-temperature charging and high-temperature charging, respectively, and these values are increased by the set value B or the set value C each time low-temperature charging or high-temperature charging is repeated. In addition, COUNT1 and C
The added value of UNT2 corresponds to the integrated value の in the above embodiment.

In the following, the processing steps will be described in order. First, in step 31, the temperature correction flag is checked to determine whether the temperature correction has been completed. If it is the first processing cycle, the flag is in the reset state, the added value (integrated value Σ) of COUNT1 and CNT2 is obtained in step 32, and it is determined in step 33 whether the value is less than the value “30” corresponding to the set value D. I do. If YES, normal charging is selected in step 34, or if NO, equal charging is selected in step 35, and in any case, the temperature correction flag is set in step 36 and the processing unit 30 is completed. .

The normal charging or the equal charging selected by the processing unit 30 is executed by a charging processing unit (not shown), and the processing unit 40 is started simultaneously with the completion of the charging. Processing unit 40
First, in step 41, it is determined whether or not the battery temperature (corresponding to the storage battery temperature T in the above embodiment) is equal to or lower than a reference value A (for example, 10 ° C.). Is added to the set value C (for example, 3) corresponding to the second weight value.
Go to 3 and set CNT1 to the set value B corresponding to the first weight value.
(For example, 2) is added. Then, in step 44, the charging mode executed immediately before is checked, and if the charging is equal, the values of CNT1 and CNT2 are reset in step 45 (COUNT1 = COUNT2 = 0), and the processing section 40 is completed.

According to the above-described soft embodiment, the rate of increase of the added value (integrated value と) of CNT1 and CNT2 changes in accordance with the frequency of low-temperature charging. It is possible to determine the timing of switching to, and it is possible to obtain the same operational effects as in the above embodiment.

[0030]

According to the present invention, the past temperature history can be added to the judgment data, and the appropriate timing of the execution of the uniform charging can be determined.

[Brief description of the drawings]

FIG. 1 is a principle diagram of the present invention.

FIG. 2 is a system configuration diagram of an embodiment.

FIG. 3 is a block diagram of a main part of a hardware logic when the embodiment is realized by hardware;

FIG. 4 is a flowchart of a main part of the software when the embodiment is realized by software.

FIG. 5 is a conceptual system configuration diagram of a conventional example.

FIG. 6 is a circuit diagram of a main part of a conventional example.

[Explanation of symbols]

 16: Charge start switch (signal generating means) 17: Temperature sensor (temperature measuring means) 21: First comparison circuit (temperature determining means) 25: Input circuit (signal generating means) 26: First weighting circuit (weighting means) 27 : Second weighting circuit (weighting means) 29: integrating circuit (integrating means) 31: charging method switching circuit (charging command / resetting means)

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H02J 7/00-7/36

Claims (1)

(57) [Claims] 1. A first charging operation in response to a predetermined charge command, in which charging is completed when a rise in terminal voltage stops, or charging is completed when a predetermined time elapses after the rise in terminal voltage stops. A temperature measuring means for measuring the temperature of the storage battery or the environmental temperature of the storage battery, wherein the temperature is measured by the temperature measuring means. If the temperature exceeds or exceeds a predetermined reference temperature, the first
Temperature judgment means for outputting a judgment signal of the above, while outputting a second judgment signal when the temperature is below or below the reference temperature;
Signal generating means for generating a count signal each time the first charging operation is performed;
Weighting means for giving a second weight value larger than the first weight value to the count signal in response to the second determination signal while giving the weight value to the count signal; and integrating the weighted count value Integrating means; when the integration result of the integrating means is less than or less than a predetermined reference value, the first
A charging command for instructing the second charging operation while outputting a charging command for instructing the second charging operation, and a charging command for resetting the integrated value of the integrating means when the current value is equal to or more than a predetermined reference value. A charging system for an electric vehicle, comprising: reset means;