JPH10285711A - Battery charging device for electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To fully charge batteries in a shortest time without causing damages to them. SOLUTION: This device charges the batteries of an electric vehicle 1 which travels with an electric motor 5 driven by 'n' pieces of batteries B1 to Bn connected in series. In this case when the voltage across terminals of each battery Bi (1<=i<=n) reaches a given level or higher, charging current to the battery Bi is bypassed and a battery monitor BMi , which outputs signal to indicate that the charging current was bypassed, is connected in parallel. Furthermore, by controlling an inverter 2 formed the number battery Bi to which no charging current is supplied, charging current (regenerative current) to be supplied from the electric motor 5 to the batteries Bi when the electric vehicle 1 is braked is controlled, to prevent the overcharge of the battery Bi and the supply of excessive charging current. In addition, a function can be added to the battery monitor BMi for maintaining the charging current at the level close to a maximum permissible charging current, which does not damage the battery Bi from the temperature of the electrolyte of the battery Bi .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery charging device for an electric vehicle, and more particularly, to a battery charging device that does not impair the battery.
The present invention relates to a technique for fully charging a battery in a shortest time.

[0002]

2. Description of the Related Art As a technique for greatly shortening a charging time of a battery mounted on an electric vehicle, for example, Japanese Unexamined Patent Publication No.
As disclosed in Japanese Unexamined Patent Publication No. 17415, the maximum charge current that does not cause a failure in the battery while feedback-controlling the charge current so that the temperature of the electrolyte solution of the battery (hereinafter, referred to as “liquid temperature”) is close to the maximum allowable temperature. A technology for charging the battery is known.

[0003]

However, a battery mounted on an electric vehicle generally has a configuration in which about 10 to 30 batteries are connected in series, so that the charge capacity and the internal resistance among the batteries vary. In view of the above, in order to significantly reduce the charging time while preventing the battery from being damaged, the charging current must be controlled in accordance with the battery having the highest liquid temperature. In this case, since charging is completed from the battery with the highest liquid temperature, charging of the battery with the low liquid temperature is not completed in the same time. If the charging time is extended to complete the charging of the battery, the charged battery is overcharged, which may shorten the life of the battery. That is, in the conventional charging method, it was not possible to completely charge all the batteries in the shortest time without causing any trouble to the batteries.

[0004] In view of the above problems, the present invention has an object to provide a battery charging device for an electric vehicle that can fully charge a battery in a shortest time without causing a failure in the battery. And

[0005]

SUMMARY OF THE INVENTION Therefore, an invention according to a first aspect of the present invention is directed to a battery charging device for charging an electric vehicle which runs by driving an electric motor with a plurality of batteries connected in series. Charging current supply means for supplying the battery with a charging current for charging the battery; bypass means for bypassing the charging current to each of the batteries; and a voltage for detecting a voltage between terminals of each of the batteries. Detecting means, means for operating the bypass means when the detected terminal-to-terminal voltage is equal to or higher than a predetermined voltage, operating state detecting means for detecting the operating state of the bypass means, Charging current control means for controlling the charging current from the charging current supply means based on the operating state.

With this configuration, when the voltage between the terminals of the battery becomes equal to or higher than the predetermined voltage, the bypass means operates to bypass the charging current to the battery. That is, since the state of charge of the battery is closely related to the voltage between the terminals of the battery, as shown in FIG. The battery is no longer supplied, and overcharging of the battery is prevented. In addition, since the charging current supplied from the charging current supply unit is controlled based on the operation state of the bypass unit, that is, the state of the charged battery, charging is completed by appropriately setting the control contents. An excessive charging current is prevented from being supplied to a battery that has not been turned on. Therefore,
By preventing overcharging of the battery and supply of an excessive charging current to the battery, all the batteries are fully charged without damaging the battery.

According to a second aspect of the present invention, the means for operating the bypass means includes a temperature detecting means for detecting the temperature of the electrolyte of each battery, and a temperature detecting means for detecting the temperature of the electrolyte. Temperature correction means for delaying the timing of bypassing the charging current. By doing so, the temperature of the battery electrolyte rises,
The timing for bypassing the charging current to the battery is delayed. That is, as shown in FIG. 3, the maximum charging current that can be supplied without causing a failure to the battery increases as the temperature of the electrolyte of the battery increases. The charging current supplied to is increased. Therefore, by appropriately setting the delay characteristics, the battery can always be charged near the maximum allowable charging current, and the charging time can be reduced.

According to a third aspect of the present invention, when the detected temperature is lower than a predetermined temperature, the temperature compensating means reduces a bypass current for bypassing a charging current to the battery as the temperature rises. When the detected temperature is equal to or higher than a predetermined temperature, a temperature characteristic correction unit that increases the bypass current with a rise in temperature is provided. With this configuration, when the temperature of the electrolytic solution of the battery is equal to or lower than the predetermined temperature, the bypass current decreases as the temperature increases, so that the charging of the battery is promoted. Further, when the temperature of the electrolyte of the battery becomes equal to or higher than the predetermined temperature, the bypass current increases with the temperature rise, so that the battery temperature rise is suppressed, and the battery failure due to the excessive temperature rise is prevented.

According to a fourth aspect of the present invention, the charging current control means adds the number of activated bypass means and reduces the charging current from the charging current supply means based on the addition result. did. With this configuration, the charging current supplied to the battery is reduced based on the total number of activated bypass means, that is, the total number of charged batteries, so that the charging of the battery that has not been completed can be performed. Is prevented from being supplied with an excessive charging current, and a battery failure is prevented.

According to a fifth aspect of the present invention, the charging current supply means supplies a charging current generated by an electric motor that rotates together with wheels of the electric vehicle when the electric vehicle is braked. With this configuration, the kinetic energy of the electric vehicle is converted into electric energy by the electric motor, and the electric energy charges the battery. Therefore, since the kinetic energy is regenerated using the existing equipment, the consumption of the battery is suppressed while suppressing the cost increase as much as possible.

According to a sixth aspect of the present invention, there is provided an engine, a generator driven by the engine, and charging current limiting means for limiting the charging current to the battery based on the charging current supplied from the generator. And the charging current supply means supplies charging current from the electric motor and charging current from the generator. With this configuration, the charging current is supplied from the generator in addition to the charging current from the electric motor, so that the electric vehicle can be used even in a place where there is no battery charging facility. Also, for example, even if the generator is operating at the maximum capacity during the rapid acceleration of the electric vehicle, the charging current to the battery is limited based on the charging current supplied from the generator, so that excessive The supply of the charging current is prevented, and the failure of the battery is prevented.

According to a seventh aspect of the present invention, the charging current supply means is configured to supply a charging current by an external charger installed outside the electric vehicle. With this configuration, even while the electric vehicle is being stored, all the batteries are completely charged by the external charger without causing any damage to the batteries. Therefore, the travelable distance of the electric vehicle can be extended.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the attached drawings. FIG. 1 is a system configuration diagram showing a first embodiment of a battery charging device for an electric vehicle according to the present invention. The electric vehicle (hereinafter, referred to as “vehicle”) 1 in the present embodiment includes n batteries B _{1 to} B B connected in series.
_n , an inverter 2 for converting a DC current supplied from the batteries B _{1 to} B _n into an AC current, an AC motor 5 for driving the driving wheels 3 of the vehicle 1 via a differential gear 4, and braking the vehicle. An electronic control brake 6 attached to each wheel, a brake controller 7 for controlling a braking force of the electronic control brake 6, a vehicle controller 8 for performing various controls of the vehicle 1 based on an accelerator signal, a vehicle speed signal, and a brake signal; Inverter 2 and brake controller 7 based on a signal from vehicle controller 8
And an inverter / brake control circuit 9 for performing the above control.

The inverter / brake control circuit 9
The vehicle 1 is controlled by the AC motor
5 when powering the vehicle with the power of
Powering control to control the current flowing during braking of the vehicle 1.
Indicates that the battery B₁
~ B_nRegenerative control to charge the battery. Also, battery B
₁~ B_nBattery B as a configuration for controlling the charging of₁~
B_nMonitor the voltage between terminals of each battery.
When the pressure exceeds a predetermined value, the charging current to the battery is bypassed.
Passes and indicates that the battery is fully charged
Battery that outputs a signal (hereinafter referred to as “charge completion signal”)
Remonitor BM₁~ BM _nAre connected in parallel. Bag
Teri monitor BM₁~ BM_nThe liquid temperature T of each battery
Temperature sensor (temperature detecting means) T such as a thermistor to be detected
H₁~ TH_nAnd the battery monitor BM₁
~ BM_nIs the battery B based on the detected liquid temperature T.₁
~ B_nControl so that the charging current of the battery is near the allowable charging current
I do. The battery monitor BM₁~ BM_nIs the voltage
Detecting means, bypass means, means for activating bypass means
Act as step, operating state detecting means and temperature compensating means
You.

Further, there is provided an addition circuit 10 for calculating the number of charged batteries by adding the charge completion signals from the battery monitors BM _{1 to} BM _n, and when the vehicle 1 is braked, the calculation result is added to the calculation result. inverter brake control circuit 9 on the basis of the controls the charging current to the battery B ₁ .about.B _n performs regeneration control of the inverter 2. In addition,
The inverter / brake control circuit 9 and the addition circuit 10
It functions as a power supply controller 11 that performs powering control and regeneration control of the vehicle 1. Further, reference numeral 1 not described above
Reference numeral 2 denotes a contactor that operates in conjunction with turning on an ignition switch (not shown). Further, in the above configuration, the AC motor 5 acts as charging current supply means, and the inverter / brake control circuit 9 and the inverter 2
Functions as charging current control means.

FIG. 2 is an electric circuit diagram showing a specific configuration of the battery monitors BM _{1 to} BM _n . Arbitrary battery monitors BM _i and BM _i-1 (where i = 2 to n-1)
Is shown. Since the battery monitors BM _i and BM _i-1 have the same configuration, in the following description, the battery monitor B
Only describes M _i, the description of the battery monitor BM _i-1 is omitted.

[0017] Battery monitor BM_iIs the battery B_iof
Terminal voltage V_iR that divides_1i, R_2iAnd the reference voltage
V_refPower supply V_refiAnd the resistance R_2iBy partial pressure
Voltage V_2iAnd reference voltage V_refV_2i≧ V
_ref, An operational amplifier U that outputs a signal_1iWhen,
Operational amplifier U_1iBypass charging current based on output from
Transistor Q_iAnd the transistor Q_iCollector
R connected to the side _3i, R_4iAnd the resistance R_3iAt both ends of
Compare the voltage_iBypasses the charging current
Is detected, and the detection signal is added to the addition circuit 10 (see FIG. 1).
Amplifier U to output to_2iAnd protect the circuit
Diode CR_iAnd is comprised.
The resistance R_2iAt both ends of the battery B_iLiquid temperature T_iTo
Temperature sensor TH to detect_iIs connected.

Here, the temperature sensor TH _i has a negative temperature coefficient whose resistance value decreases as the liquid temperature T _i increases. In addition, the isolation amplifier U
_2i is to inter-terminal voltage V _i of the battery B _i is prevented from being applied to a summing circuit 10. Furthermore, the diode CR _i, when a reverse voltage is applied to the battery B _i for some reason, is for protecting the battery monitor BM _i.

[0019] Reference numeral Rb _i in the figure, a battery B _i
Is the internal resistance of Next, the operation of the battery monitor BM _i made of such configurations. Immediately after starting the charging of the battery B _i, the battery B _i terminal voltage V _i of
Since the voltage V _{2i divided} by the resistor R _2i (hereinafter referred to as “divided voltage”) is smaller than the reference voltage V _ref , the transistor Q _i does not operate. Therefore, the charging current i is not bypassed, and the battery B
_i is charged.

[0020] with the progress of charging of the battery B _i, the terminal voltage V _i of the battery B _i gradually increases, the divided voltage V _2i is also gradually increased. When the divided voltage V _2i becomes equal to or higher than the reference voltage V _ref, the signal is output to the transistor Q _i from the operational amplifier U _1i. Then, the transistor Q _i operates and the charging current i is bypassed. On this occasion,
Since current flows to the resistor R _3i, resistance across a voltage difference occurs in the R _3i, the isolation amplifier U having detected this
_2i outputs a charge completion signal to the addition circuit 10.

[0021] In summary, battery monitor BM _i, when the inter-terminal voltage V _i of the battery B _i exceeds a predetermined voltage, as well as to the charging of the battery B _i by bypassing the charge current is not performed, the charge Outputs a completion signal. In addition to the function described above, the battery monitor BM _i is performing temperature correction based on the liquid temperature T _i of the battery B _i.

[0022] That is, as shown in FIG. 3, the maximum charging current i _max without harm to the battery B _i are state of charge (referred to the state of charge of when a 100% fully charged. Hereinafter the same) SOC In the same case, the higher the liquid temperature T _i becomes, the larger the liquid temperature T _i becomes. Therefore, the temperature sensor TH _i whose resistance value based on the liquid temperature T _i of the battery B _i is changed, by changing the divided voltage V _2i, it changes the timing at which the transistor Q _i to bypass the charging current i. Specifically, when the liquid temperature T _i of the battery B _i is increased, the resistance value of the temperature sensor TH _i is reduced, the combined resistance of the resistor R _2i and the temperature sensor TH _i decreases. Thus, the operational amplifier U divided voltage V _2i output to _1i is also reduced, the divided voltage V _2i reference voltage V _ref becomes more than the battery B _i terminal voltage V _i of
Becomes larger.

The reference voltage _Vref for bypassing the charging current is, as shown in FIG.
% Approaching the considering that the inter-terminal voltage V _i of the battery B _i is rapidly increased, a time of liquid temperature T _i is hot, and the charge state is set based on the allowable maximum current of around 100%. Next, the power supply controller 11 including the inverter / brake control circuit 9 and the addition circuit 10 will be described.

The adder circuit 10 includes a battery monitor BM _1-
Based on the charging completion signal outputted from the BM _n, number of battery monitor BM ₁ to Bm _n is calculated whether the bypassing the charging current, and outputs the result to the inverter and brake control circuit 9. The inverter / brake control circuit 9 is based on an output signal from the addition circuit 10 and an accelerator signal, a vehicle speed signal, and a brake signal from the vehicle controller 8, via the power running control, the regenerative control, and the brake controller 7 of the inverter 2. The electronic control brake 6 is controlled.

Here, when a command for powering the AC motor 5 is issued from the vehicle controller 8, the inverter / brake control circuit 9 does not use the output signal from the adding circuit 10 and controls the powering of the AC motor 5. Do only. On the other hand, when a command to regenerate AC motor 5 is issued from vehicle controller 8, regenerative current of inverter 2 is controlled based on an output signal from addition circuit 10. When the regenerative current is small and the braking force of the AC motor 5 is insufficient and the braking force of the vehicle 1 is insufficient, a command is issued to the brake controller 7 to increase the braking force. Accordingly, a predetermined braking force can be exerted even during the regenerative operation.

FIG. 5 is a system configuration diagram showing a second embodiment of the battery charging device for an electric vehicle according to the present invention.
In the present embodiment, the battery charging device according to the present invention is applied to a so-called hybrid electric vehicle. In addition,
The same components as those in the first embodiment (see FIG. 1) are denoted by the same reference numerals, and description thereof will be omitted. The hybrid electric vehicle 20 includes an AC generator (charging current supply unit) 2 that uses the output of the engine 21 as a drive source even during regenerative operation.
2 is operated, and the alternating current from the AC generator 22 into a DC current by the inverter 23, can be charged driving and battery B ₁ .about.B _n AC motor 5 by the DC current. Accordingly, the charging current control means for controlling supply to the battery B ₁ .about.B _n the direct current from the inverter 23, diode 24, transistor 25 and the gate drive circuit 26 is provided. In such a configuration, the power supply controller 27 includes the addition circuit 10, the inverter / brake control circuit 9, and the gate drive circuit 26.

The gate drive circuit 26 includes an inverter
Based on a signal from the brake control circuit 9, the duty of the current supplied to the base of the transistor 25 is controlled. Transistor 25, based on the current supplied from the gate drive circuit 26, a DC current from the inverter 23, is branched to the battery B ₁ ~B _n. Note that the diode 24
, Upon non-operation of the transistor 25, the DC current from the inverter 23 is intended to not be supplied to the battery B ₁ ~B _n.

Next, the control of the battery charger for the electric vehicle shown in FIGS. 1 and 5 will be described with reference to the flowcharts shown in FIGS. This routine is
This shows the control of the power supply controller 11 or 27 which is started at the same time as the ignition switch is turned on, and can be used in common by both. In step 1 (abbreviated as “S1” in the figure, the same applies hereinafter), various initializations such as initialization of variables are performed.

In step 2, it is determined whether or not the inverter / brake control circuit 9 has issued a regenerative command to the inverter 2. When the regenerative command has been issued (Yes),
Proceeding to step 3, when the regeneration command has not been issued (No), the processing of step 2 is repeated. In step 3, a loop counter i for specifying the battery and a variable j indicating the number of charged batteries are initialized.
Specifically, it is assumed that the loop counter i = 1 (first battery B ₁ ) and the variable j = 0 (no charged battery is present).

[0030] In step 4, whether or not the battery B _i has completed charging, it is determined based on the charging completion signal from the battery monitor BM _i, When charging is not completed (Ye
s) In step 5, the variable j is incremented. If charging is not completed (No), the process proceeds to step 6. In step 6, the loop counter i is incremented.

In step 7, it is determined whether or not the loop counter i has become larger than the number n of batteries (i> n). If i> n (Yes), the process proceeds to step 8,
If i ≦ (No), the process returns to step 4. here,
Processing in steps 3 7 is a process performed by the addition circuit 10 is used for determining how many of the battery of the battery B ₁ .about.B _n is charging completed.

In step 8, it is determined whether or not the vehicle is a hybrid electric vehicle. If the vehicle is a hybrid electric vehicle (Yes), the process proceeds to step 9, and if not, the process proceeds to step 10. . In step 9, it is determined whether or not the vehicle is in the regeneration mode. If the vehicle is in the regeneration mode (Yes), the process proceeds to step 10. If the vehicle is not in the regeneration mode (No), the process proceeds to step 15.

In step 10, it is determined whether or not the regenerative current from the inverter 2 is equal to or less than the maximum charging current.
If it is the maximum charging current (Yes), the process proceeds to step 11, and if regenerative current> maximum charging current (No), a command is output to inverter 2 in step 12 to reduce the regenerative current. In step 11, the regenerative braking force, that is, the braking force that can be generated by the AC motor 5 is:
It is determined whether the required braking force is smaller than a required braking force determined based on a brake signal or the like output from the vehicle controller 8. If regenerative braking force <required braking force (Yes), the process proceeds to step 13 and regenerative braking is performed. If force ≧ required braking force (No), the process returns to step 2.

In step 13, since the regenerative braking force is insufficient with respect to the required braking force, the shortage of the braking force is compensated for by the electronic control brake 6, and the brake controller 7 controls the brake controller 7 to secure the braking force of the vehicle. Outputs an operation command. In step 14, it is determined whether or not the traveling has been completed. If the traveling has been completed (Yes), the processing of this routine is terminated, and if the traveling has been continued (N
o) Return to step 2.

Steps 15 to 19 show the control contents when the hybrid electric vehicle is not in the regenerative mode, that is, during power running or stopped. In step 15, it is determined whether power generation is necessary to charge the battery B ₁ .about.B _n, if power generation is needed (Yes), the process proceeds to step 16, if the power generation is required (No) ,
Proceed to step 14.

In step 16, it is determined whether or not the generated current of the generator 22 is larger than the required current calculated based on the output of the adding circuit 10, and it is determined that the generated current is greater than the required current (Ye).
If s), the process proceeds to step 17, and if the generated current ≦ the required current (No), the process proceeds to step 14. In step 17, the generated current is greater than the required current, the gate drive circuit 26, outputs a command to decrease the charging current to the battery B ₁ .about.B _n by decreasing the duty ratio of current supplied to the transistor 25 I do.

In step 18, it is determined whether or not the generated current of the generator 22 is excessive with respect to the motor request current required by the AC motor 5 for running the vehicle. If the generated current is excessive (Yes) ; Generated current> required motor current),
Proceeding to step 19, if the generated current is not excessive (N
o: power generation current ≦ motor required current), and return to step 16.

To summarize the processing in steps 1 to 19 described above, first, the power supply controller 11
Alternatively, when the regenerative control command is issued (step 2), the number 27 checks the number of the charged batteries (steps 3 to 7). Next, if the vehicle is not a hybrid electric vehicle (step 8), the regenerative current is
_The inverter 2 is controlled so as to be less than the maximum charging current of _{1 to Bn.}
(Steps 10 and 12), and controls the operation of the electronic control brake 6 as necessary so that the braking force of the vehicle is not insufficient (Steps 11 and 1).
3). On the other hand, when the vehicle is a hybrid electric vehicle (step 8), in the regeneration mode (step 9),
Performs steps 10 to step 13, not in the regeneration mode, and, if power generation is needed (Step 9 and Step 15), performs the limitation of charging current to the battery B ₁ .about.B _n (Step 16 And step 17), and control the generated current (step 18 and step 1).
9).

Accordingly, the same control is performed regardless of whether the vehicle is a hybrid electric vehicle or not, so that the development cost of the control circuit of the vehicle can be reduced. Further, since the charging current to the battery B ₁ .about.B _n becomes minimum necessary, it is possible to prevent damage to the battery. Further, power generation control for powering the vehicle is performed, so that consumption of fuel for power generation can be suppressed as much as possible, thereby improving fuel efficiency and suppressing the impact on the global environment as much as possible.

[0040] 8-11 show another embodiment with improved control accuracy of battery monitor BM _i. That is,
8, a battery sensor BM _i is a temperature sensor T
Between the H _i and the operational amplifier U _1i, has a configuration which is interposed a temperature characteristic correction circuit 30 as a temperature characteristic correction means. Temperature characteristic correction circuit 30, as shown in FIG. 9, the liquid until the temperature reaches a predetermined temperature, to reduce the bypass current by gradually decreasing the current supplied to the transistor Q _i with increasing liquid temperature, After the liquid temperature reaches the predetermined temperature,
By increasing the bypass current by causing with increasing liquid temperature increases the current supplied to the transistor Q _i gradually, to protect the battery B _i.

The temperature characteristic correction circuit 30 is realized by various circuits. As one embodiment, a digital temperature characteristic correction circuit shown in FIG. 10 and an analog temperature correction circuit shown in FIG. 11 will be described. 10, the temperature characteristic correction circuit 30 of the digital system, a resistor R ₁₀₀ to the reference voltage V _ref is applied, the temperature sensor TH _i
And ROMU ₁₀₁ for storing an A / D converter U _100, a table to find the corrected based transformed combined resistance value R the resistance value R 'for converting the combined resistance value R of the resistor R ₁₀₀ to digital values, constituted the retrieved resistance values R 'and D / a converter U ₁₀₂ to be converted to an analog value, including.

In FIG. 11, an analog temperature characteristic correction circuit 30 includes a resistor R ₅₀ to which a reference voltage _Vref is applied.
, A resistor R ₅₁ connected to the temperature sensor TH _i , and a resistor R
An operational amplifier U ₃ which compares the voltage and ground voltage that is a voltage drop by _51, a resistor R ₅₂ which connects the input side of the operational amplifier U ₃ and an output side, the diode connected to the input side of the operational amplifier U ₃ CR ₅₁ ~ CR ₅₂ and the reference voltage V _ref
And thereby connects the output of the operational amplifier U _3, configured to include a resistor R ₅₃ to R ₅₈ the output of the middle diode CR ₅₁ ~CR ₅₃ are respectively connected, the.

The temperature characteristic correction circuit 30 having such a configuration
According to FIG. 9, the temperature characteristic as shown in FIG. 9 is obtained. FIGS. 10 and 11 show only one embodiment of the temperature characteristic correction circuit 30, and may be realized by any circuit configuration. FIG. 12 is a system configuration diagram showing a third embodiment of the battery charging device for an electric vehicle according to the present invention. In the present embodiment, a battery B is supplied from an external charger 40 as charging current supply means installed outside the vehicle.
To M ₁ ~BM _n is intended for charging. Note that the first
The same components as those of the second embodiment (see FIGS. 1 and 5) are denoted by the same reference numerals, and description thereof will be omitted.

The external charger 40 constituting the power supply controller 41 receives a signal from the addition circuit 10, that is, the battery B
The output charging current is controlled based on a signal indicating how many of M _{1 to} BM _n have been charged. Specifically, with an increase in the number of battery charging is completed, gradually reduce the charge current to limit the excessive current supply to the battery BM ₁ ~BM _n.

Therefore, by performing such control,
The same effects as in the first and second embodiments can be obtained. In the first to third embodiments described above, the battery monitors BM _{1 to} BM _n and the temperature characteristic correction circuit 30
Is composed of an electric circuit, but may be configured to be controlled in software by an ECU (Electronic Control Unit) containing a microcomputer, for example.

[0046]

As described above, according to the first aspect of the present invention, overcharging of the battery and supply of an excessive charging current to the battery are prevented, and all the batteries are prevented from being damaged. Can be fully charged.
According to the second aspect of the invention, the battery can always be charged near the maximum allowable charging current, and the charging time can be reduced.

According to the third aspect of the present invention, it is possible to promote the charging of the battery while suppressing an excessive rise in the temperature of the electrolyte of the battery and preventing the battery from being damaged. According to the fourth aspect of the present invention, it is possible to prevent an excessive charging current from being supplied to a battery that has not been fully charged, and to prevent a failure of the battery. According to the fifth aspect of the invention, it is possible to suppress the consumption of the battery while minimizing the cost increase.

According to the invention described in claim 6, the electric vehicle can be used even in a place where there is no battery charging facility. In addition, supply of an excessive charging current to the battery is prevented, and failure of the battery is prevented. According to the seventh aspect of the present invention, all the batteries are fully charged without obstructing the batteries during storage of the electric vehicle, and the mileage of the electric vehicle can be extended.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing one embodiment of the battery sensor according to the first embodiment;

FIG. 3 is a diagram showing a relationship between a charging state and a maximum allowable charging current.

FIG. 4 is a diagram showing a relationship between a state of charge and a voltage between battery terminals.

FIG. 5 is a system configuration diagram showing a second embodiment of the present invention.

FIG. 6 is a flowchart showing control contents of a power supply controller used in the systems shown in FIGS. 1 and 5;

FIG. 7

FIG. 8 is a schematic circuit diagram showing another embodiment of the battery sensor of the above.

FIG. 9 is a diagram showing a relationship between a battery temperature and a bypass current in the temperature characteristic correction circuit according to the first embodiment;

FIG. 10 is a digital temperature characteristic correction circuit showing an embodiment of the above temperature characteristic correction circuit.

FIG. 11 is an analog temperature characteristic correction circuit showing another embodiment of the temperature characteristic correction circuit of the above.

FIG. 12 is a system configuration diagram showing a third embodiment of the present invention.

[Explanation of symbols]

1 electric vehicle 2 inverter 5 electric motor 9 inverter brake control circuit 10 the adding circuit 20 hybrid electric vehicle 21 engine 22 electric generator 23 converter 24 diode 25 transistor 26 gate drive circuit 30 the temperature characteristic correction circuit 40 external charger B ₁ .about.B _n battery BM ₁ to Bm _n battery monitor TH ₁ to TH _n temperature sensor

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁶ Identification code FI H02J 7/10 H02J 7/10 B

Claims (7)

[Claims] An electric vehicle that runs by driving an electric motor with a plurality of batteries connected in series is a battery charging device that charges the battery, and a charging current for charging the battery with the battery. Current supply means for supplying the battery, bypass means for bypassing the charge current to each of the batteries, voltage detection means for detecting the voltage between the terminals of each of the batteries, and the detected inter-terminal voltage is equal to or higher than a predetermined voltage. Means for operating the bypass means, operating state detecting means for detecting the operating state of the bypass means, and charging current from the charging current supply means based on the detected operating state of the bypass means. A battery charging device for an electric vehicle, comprising: charging current control means for controlling. 2. The temperature control device according to claim 1, wherein the means for operating the bypass means includes a temperature detecting means for detecting a temperature of the electrolyte of each battery;
2. The battery charging device for an electric vehicle according to claim 1, further comprising: a temperature correction unit configured to delay a timing of bypassing a charging current to the battery with a rise in the detected temperature. 3. The temperature correction means according to claim 1, wherein, when the detected temperature is lower than a predetermined temperature, a bypass current for bypassing a charging current to said battery is reduced with a rise in temperature, and said detected temperature is reduced to a predetermined temperature. 3. The battery charging device for an electric vehicle according to claim 1, further comprising a temperature characteristic correction unit configured to increase the bypass current as the temperature increases. 4. 4. The charge current control means is configured to add the number of activated bypass means and reduce the charge current from the charge current supply means based on the addition result. The battery charging device for an electric vehicle according to any one of the above. 5. The electric vehicle according to claim 1, wherein said charging current supply means supplies a charging current generated by an electric motor that rotates together with wheels of said electric vehicle during braking of said electric vehicle. A battery charging device for an electric vehicle according to any one of claims 1 to 3. 6. An engine, a generator driven by the engine, and charging current limiting means for limiting charging current to the battery based on charging current supplied from the generator, The battery charging device for an electric vehicle according to claim 5, wherein the charging current supply means is configured to supply a charging current from the electric motor and a charging current from the generator. 7. The battery for an electric vehicle according to claim 1, wherein said charging current supply means supplies a charging current by an external charger installed outside said electric vehicle. Charging device.