JPH0974611A - Charge control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charge control device for supplying a stable current to a motor from a battery and for obtaining a high charging efficiency on charging in the charge control device of a hybrid-type electric vehicle which drives an automobile by discharging electricity which is charged at the battery by a charging machine. SOLUTION: A charge control device has a charge/discharge detection means 20 for detecting the charged and discharged state of a battery, a switching means 30 for periodically fluctuating the charge current of the battery, and control means 24 and 26 for intermittently supplying charge current to the battery by the switching means when the charge/discharge detection means 20 at least detects that the battery is in charged state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charge control device, and more particularly to a battery charge control device for a hybrid electric vehicle.

[0002]

2. Related Background Art In recent years, development of an electric vehicle that is low in pollution to a vehicle running by an internal combustion engine has been advanced. In this electric vehicle, a high output motor is used to obtain a large output, and a large amount of electric power is required to drive this motor. For this reason, a rechargeable secondary battery, which has a large capacity and is usually used, is used for an electric vehicle and is appropriately charged.

In such an electric vehicle, the cruising distance per charge is short, and the number of installed batteries is large, so that the vehicle weight is heavy. Therefore, in order to have a long cruising distance and a small number of installed batteries, a series-type hybrid electric vehicle in which another generator such as a small engine is used to operate a generator to appropriately charge a secondary battery has appeared. ing.

FIG. 6 shows a schematic configuration diagram of this hybrid electric vehicle. As shown in FIG. 6, a power converter 104 is electrically connected to the motor 102, and the power converter 104 is electrically connected. Is supplied with electricity from a battery 110, which is a secondary battery, via cables 106 and 108. Cables 112 and 114 extend from the cables 106 and 108, respectively, and these cables 112 and 114 are electrically connected to a generator 116. This generator 116 is, for example, a small engine 1
Driven by 18. An ammeter 120 is provided in the cable 106 so that the current value and the current direction can be detected.

Reference numeral 122 is a remaining capacity calculator for the battery 110, and the input side of the remaining capacity calculator 122 is
In addition to the current value from the ammeter 120, the cable 10
The voltage value between 6 and 108 is input. Then, the remaining capacity calculator 122 calculates the remaining capacity of the battery 110 based on the input information, and when it is determined that the remaining capacity of the battery 110 has decreased based on the calculation result, an output signal is supplied to the engine 118. Then, the generator 116 operates. As a result, the battery 11
0 will be charged appropriately.

Further, during braking, power is also generated by the motor 102, and when the electromotive voltage is larger than the voltage value between the cables 106 and 108, the battery 110 is also charged (energy regeneration).

[0007]

In the above system, the charging current to the battery 110 is usually a continuous current. However, when charging the battery 110, it is known that the charging efficiency is better when the charging current is not a continuous current but a rectangular wave pulse current. In pulse charging, since the magnitude of the charging current is repeatedly changed with time, the temperature rise of the battery 110 is small, and compared to the continuous current charging, a large current can be charged and the deep portion of the electrode plate can be efficiently charged. The charging capacity is increased about 1.5 times compared to the current.

Therefore, it is conceivable that the above system also supplies a pulse current at the time of charging to downsize the battery 110 and reduce the number of connected batteries. At this time, it is necessary to supply the pulse current only during charging and to supply a stable constant current to the motor 102 during discharging. The present invention has been made based on the above-mentioned circumstances, and an object of the present invention is to provide a charging control device which can supply a stable current from a battery to a motor while obtaining high charging efficiency during charging. .

[0009]

In order to achieve the above-mentioned object, the invention of claim 1 drives a generator by an internal combustion engine to charge a battery, and discharges the charged electricity to drive a motor. In a charging control device for a hybrid electric vehicle that is driven and traveling, a charging / discharging detection unit that detects a charging state and a discharging state of the battery, a switching unit that can periodically change a charging current of the battery, and the charging / discharging unit. And a control unit that intermittently supplies a charging current to the battery by the switching unit when the discharge detecting unit detects that the battery is in the charging state.

Therefore, when the battery is in the charging state, the charging current fluctuates periodically and flows intermittently to the battery.
The charging efficiency is improved. Further, in the invention of claim 2, in a charge control device for a hybrid electric vehicle, which drives a generator by an internal combustion engine to charge a battery, discharges the charged electricity, and drives a motor to drive the battery. Charging / discharging detection means for detecting the charging state and discharging state of the battery, switching means capable of periodically varying the charging current of the battery, and a connection circuit provided between the battery and the motor in parallel with the battery. And a control means for intermittently supplying a charging current to the battery by the switching means when the charging / discharging detection means detects that at least the battery is in the charging state. Is characterized by.

Therefore, when the charging current fluctuates periodically and flows intermittently to the battery, the charging current is preferably stored in the capacitor while the switching means stops or reduces the energization of the charging current to the battery. To be done. Furthermore, when the battery is discharged, the discharge current from the battery is stabilized. In the invention of claim 3,
The charge state is a state in which the generator is driven by the internal combustion engine to charge the battery. Therefore, the charging current generated by the generator intermittently flows to the battery and is stored therein.

Further, the invention of claim 4 is characterized in that the charging state is a regeneration state in which the motor generates electric power to charge the battery. Therefore, the charging current generated by the motor during braking of the vehicle or the like intermittently flows to the battery as regenerative energy and is stored therein. Further, the invention of claim 5 is characterized in that the switching circuit has a discharging means for constantly supplying a discharging current from the battery to the motor. Therefore, the battery can always be discharged, and the motor can always be driven well.

Further, in the invention of claim 6, the discharging state is a power running state in which the motor is driven by being supplied with electric power from the battery. Therefore,
The motor is driven by the discharge current from the battery, and the motor satisfactorily generates a driving force according to the discharge current. Further, in the invention of claim 7, the control means sets the charging / disconnecting time ratio between the charging current and the discharging current according to the charging capacity detecting means for detecting the charging capacity of the battery and the charging capacity. It is characterized by having a disconnection ratio setting means. Therefore, when the charging capacity of the battery is reduced, the connection time is set shorter than the disconnection time by setting the connection / disconnection time ratio, and the charging current flows to the battery.
The battery is charged well because the temperature rise is suppressed.

Further, the invention of claim 8 is characterized in that the charging ability detecting means includes a temperature detecting means for detecting the temperature of the battery. Therefore, the charging capacity is easily detected by the temperature of the battery.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a drive system of a series hybrid electric vehicle to which an embodiment of the present invention is applied. As shown in the figure, the high power motor 2 connected to the wheels (not shown) includes a power converter 4
Are electrically connected. The power converter 4 is electrically connected to a battery 10 such as a nickel hydrogen battery, which is a secondary battery, via cables 6 and 8. The cables 12 and 14 are branched from the cables 6 and 8, respectively.
And the cables 12 and 14 are connected to the generator 1
6 is electrically connected. The generator 16 is driven by, for example, a small engine 18 having a small displacement.

The cable 6 has an ammeter (charge / discharge detection means).
20 is interposed. The ammeter 20 can detect the magnitude of the current I and the direction of the current I. That is, the ammeter 20 can detect whether the current flowing through the cable 6 is the discharge current Id or the charging current Ic. Reference numeral 22 is a remaining capacity calculator of the battery 10,
The ammeter 20 is connected to the input side of the remaining capacity calculator 22.
In addition to the current signal from, the voltage signal corresponding to the voltage E between the cables 6 and 8 is input. And
The remaining capacity calculator 22 calculates the remaining capacity of the battery 10 based on these input information, and based on the calculation result,
When it is determined that the state of charge of the battery 10 has dropped below a predetermined value, an output signal is supplied to the engine 18 to operate the engine 18 and drive the generator 16.

In this hybrid type electric vehicle, electric power is also generated by the motor 2 during braking of the vehicle. When the electromotive voltage at this time is larger than the voltage value E between the cables 6 and 8, the battery 10 is also charged (energy regeneration). Reference numeral 24 in the drawing is a charging controller (control means). At the input side of the charge controller 24, the current signal from the ammeter 20 and the voltage signal between the cables 6 and 8, and the temperature attached to the battery 10, as in the case of the remaining capacity calculator 22, are provided. A temperature signal from a sensor (charging capacity detection means) 28 is input. This temperature sensor 28
Is for detecting the surface temperature of the battery 10. Normally, when the battery 10 deteriorates and the charging ability decreases, the temperature of the battery 10 tends to rise during charging,
By detecting the temperature change with the temperature sensor 28, the deterioration of the capacity of the battery 10 is detected.

On the other hand, on the output side, a switching circuit (switching means) 30 interposed in the cable 8 is connected. The switching circuit 30 is a circuit including a transistor, a thyristor, or a combination thereof, and the cable 8 is based on an output signal from the charge controller 24.
Charging current I
It enables periodic fluctuation of c. More specifically, the oscillation circuit 26 is incorporated in the charging controller 24, a signal is supplied from the oscillation circuit 26 to the switching circuit 30 based on the current signal from the ammeter 20, and the switching circuit 30 is accordingly responded. Is turned on and off, and the charging current Ic flowing through the cable 8 is connected and disconnected.

Reference numeral 31 in the drawing denotes a diode (discharging means), and the discharge current Id from the battery 10 can be constantly energized by the operation of the diode 31, and the driving state of the motor 2, that is, the power running is always performed. The state is secured. Hereinafter, charging control of the hybrid electric vehicle thus configured will be described.

Normally, when charging the battery 10,
It is known that the charging efficiency is better when performing the chopper control in which the current is periodically changed so as to be repeatedly turned on and off, rather than continuously flowing a constant current. Therefore, in this charging control, the switching circuit 30 is controlled to perform such chopper control.

FIG. 2 is a flow chart showing a control routine of the switching circuit control executed when the charge controller 24 determines that the current I is the charging current Ic based on the input signal from the ammeter 20. Further, FIG. 3 is a time chart of the charging current Ic obtained by executing the routine. A description will be given below with reference to FIGS. 2 and 3.

First, in step S10, the switching circuit 30 is turned on and is energized, and the energizing time is
That is, the time measured by the on-timer Ton described later is positive (Ton>
0) is determined. Immediately after the switching circuit 30 is turned on, the determination result is true (Yes).
Since the on-timer Ton is positive, the process proceeds to step S12.

In step S12, it is determined whether or not the time measured by the on-timer Ton is shorter than the predetermined time T1 (Ton <T1). Immediately after the switching circuit 30 is turned on, the determination result is true, and in this case, the process proceeds to step S14 to set the switching circuit 30 to on (switch on). At this time, the charging current Ic is Ic
Although set to 1 (see FIG. 3), this value Ic1 changes depending on the rotational speed of the generator 16 and the remaining capacity of the battery 10.

In the next step S16, it is determined whether or not the charging current Ic is positive (Ic> 0), that is, the current I is not the discharging current Id but the charging current Ic. Immediately after the start of charging, the charging current Ic is satisfactorily flowing. In this case, the determination result is true and the process proceeds to step S18. On the other hand, if the determination result in step S16 is false and the battery 10 is saturated and the charging current Ic does not flow, the process proceeds to step S26, which will be described later, and the on-timer T
reset on to 0.

In step S18, while the on-timer Ton is integrated, an off-timer Toff, which will be described later, is set to zero. The routine is repeatedly executed, and step S12
If the result of the determination is false (No) and it is determined that the time measured by the on-timer Ton exceeds the predetermined time T1, the process proceeds to step S24, and the switching circuit 30 is set to off (switch off). At this time, the charging current Ic is set to 0, but a slight amount of current may be set as the value Ic2 (shown by the broken line in FIG. 3). In this case, the switching circuit 30 may be provided with a bypass circuit having a resistance of a predetermined resistance value.

In the next step S26, an off timer Tof for measuring the time when the switching circuit 30 is turned off.
While integrating f, the on-timer Ton is reset to 0. As described above, when the on-timer Ton is reset to 0, the determination result in the previous step S10 becomes false, and in this case, the process proceeds to step S20.

In step S20, it is determined whether the time measured by the off timer Toff is shorter than the predetermined time T2 (Toff <T
2) Determine. Immediately after the switching circuit 30 is switched from on to off, the determination result is true, and in this case, the above-described step S24 and step S26 are performed.
Then, the off timer Toff is integrated. When the routine is repeatedly executed and the determination result of step S20 is false and it is determined that the time measured by the off timer Toff exceeds the predetermined time T2, the process proceeds to step S14 described above to turn on the switching circuit 30 again. To do.

As described above, the charging current Ic is as shown in FIG.
As shown in the time chart, the chopper control is performed by periodically varying the sum of the predetermined times T1 and T2 as a cycle, whereby the battery 10 is charged efficiently. It has been experimentally confirmed that the charging efficiency in this case is about 1.5 times that in the case of charging with a continuous current.

By the way, the charging controller 24 has a predetermined time T
It is also possible to adjust 1 and the predetermined time T2 according to the change with time of the charging capacity of the battery 10 (disconnection / connection ratio setting means). Specifically, the temperature sensor (charging capacity detection means) 2
The ratio T1 / T2 of the predetermined time T1 and the predetermined time T2 is decreased in accordance with the temperature rise of the battery 10 detected in step 8 to reduce the energization time of the charging current Ic. This allows
The supply amount of the charging current Ic to the battery 10 can be reduced to suppress the temperature rise of the battery 10, and the deterioration of the battery 10 can be preferably prevented.

Since the diode 31 is connected to the switching circuit 30 as described above, the switching circuit 3 is energized from the battery 10 to the power converter 4.
Regardless of whether it is 0 or 0, it is always allowed and the power running state is secured. FIG. 4 shows a schematic configuration diagram of a drive system of a series type hybrid electric vehicle in which capacitors 36 are attached to the cables 6 and 8 of the system of FIG.

The capacitor 36 can withstand a voltage E1 substantially equal to the supply voltage of the battery 10 and can store electricity like the battery 10. As a result, the switching circuit 30 is turned off, and the battery 10
It is possible to supplementarily store the charging power even when the charging to the battery is cut off. FIG. 5 is a flowchart showing a control routine of switching circuit control executed by the charging controller 24 based on the system of FIG. Hereinafter, description of the same parts as those in FIG. 2 will be omitted, and the operation of the system in FIG. 4 will be described.

In the flowchart of FIG. 5, step S22 is added to the flowchart of FIG. That is, if the determination result of step S20 is true, or if the determination result of step S12 is false, step S22
Will be executed. In step S22, it is determined whether or not the voltage E between the cables 6 and 8 is smaller than the withstand voltage E1 (E <E1). If the determination result is true and the voltage E is lower than the withstand voltage E1, the process proceeds to step S24, and the switching circuit 30 is turned off. At this time, the charging current Ic flows through the capacitor 36, and the capacitor 36 appropriately stores electric power. Therefore, it is possible to prevent the load fluctuation applied to the generator 16 by turning the switching 30 on and off, and to prevent the rotation fluctuation of the generator 16 appropriately.

On the other hand, if the determination result of step S22 is false and it is determined that the voltage E exceeds the withstand voltage E1, the process proceeds to step S14, and the switching circuit 30 is turned on. In other words, when the voltage E exceeds the withstand voltage E1, the charging current Ic is forced to flow through the battery 10, thereby preventing the deterioration of the capacitor 36.

Further, by disposing the capacitor 36 in this way, it is possible to stabilize the discharge current Id flowing from the battery 10 to the motor 2 during discharging. Thereby, the Joule loss of the battery 10 can be reduced appropriately. As described above in detail,
By using the charging control device of the present invention in a hybrid electric vehicle and controlling the charging current Ic flowing in the battery 10 by chopper, the charging efficiency of the battery 10 can be improved, and the number of batteries 10 can be reduced and the battery can be reduced. 10 itself can be miniaturized.

Further, by providing the capacitor 36 in parallel with the battery 10, the charging current Ic can be guided to the capacitor 36 to store electric power when the power supply to the battery 10 is cut off, and the load of the generator 16 can be stored. It is possible to perform good charging while reducing the above, and it is possible to suitably stabilize the discharge current Id at the time of discharging.

[0036]

As described above, according to the charge control device of the first aspect, the internal combustion engine drives the generator to charge the battery, and the charged electricity is discharged to drive the motor to drive the vehicle. In a charging control device for a hybrid electric vehicle, a charging / discharging detection unit that detects a charging state and a discharging state of a battery, a switching unit that can periodically change a charging current of the battery, and a charging / discharging detection unit include at least the battery. When the battery is in the charging state, the switching means intermittently supplies the charging current to the battery when the battery is in the charging state. By doing so, it can be flowed to the battery and the charging efficiency can be improved. As a result, the number of batteries can be reduced, and the batteries themselves can be downsized.

According to the charging control device of the second aspect,
In a charging control device for a hybrid electric vehicle that drives a generator by an internal combustion engine to charge a battery, discharges the charged electricity, and drives a motor to drive the battery, a charging control device that detects a charging state and a discharging state of the battery. At least a discharge detecting unit, a switching unit capable of periodically varying the charging current of the battery, a capacitor provided in parallel with the battery in a connection circuit between the battery and the motor, capable of storing electricity, and a charge / discharge detecting unit. When it is detected that the battery is in the charging state, the switching means is provided with the control means for intermittently supplying the charging current to the battery, so that when the charging current fluctuates periodically and flows intermittently to the battery. , While the switching means is interrupting or reducing the charging current to the battery, It can be preferably stored in the capacitor. As a result, it is possible to prevent the load fluctuation of the generator and stabilize the discharge current from the battery at the time of discharging to reduce the Joule loss in the battery.

According to the charging control device of claim 3,
In the charging state, the generator is driven by the internal combustion engine to charge the battery, so that the charging current generated by the generator can be intermittently supplied to the battery, and good charging can be performed. Further, according to the charge control device of the fourth aspect, since the charging state is a state in which the motor is generating power to charge the battery, the charging current generated by the motor and regenerated during braking of the vehicle is intermittent. It can be made to flow into the battery, and can be charged well.

According to the charge control device of claim 5,
Since the switching circuit has the discharging means for constantly discharging the discharge current from the battery to the motor, the switching circuit can always discharge from the battery and can always drive the motor well. Further, according to the charge control device of the sixth aspect, since the discharge state is a power running state in which the motor is driven by being supplied with electric power from the battery, it is possible to satisfactorily generate a driving force corresponding to the discharge current in the motor. it can.

According to the charge control device of claim 7,
Since the control means has the charging ability detecting means for detecting the charging ability of the battery and the connecting / disconnecting ratio setting means for setting the connecting / disconnecting time ratio of the charging current and the discharging current according to the charging ability,
When the charging capacity of the battery decreases, the connection time can be set shorter than the disconnection time by setting the connection / disconnection time ratio so that the charging current can flow to the battery with less charge, and the temperature rise of the battery can be suppressed to a good level. It can be charged.

According to the charging control device of claim 8,
Since the charging ability detecting means includes the temperature detecting means for detecting the temperature of the battery, the charging ability can be easily detected by the temperature of the battery.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a drive system of a series hybrid electric vehicle equipped with a charging control device of the present invention.

FIG. 2 is a flowchart showing a switching circuit control routine executed by a charging controller in FIG.

FIG. 3 is a time chart of a charging current Ic based on the switching circuit control routine of FIG.

FIG. 4 is a schematic diagram showing a drive system of a series hybrid electric vehicle equipped with a charge control device including a capacitor.

FIG. 5 is a flowchart showing a switching circuit control routine executed by the charge controller of FIG.

FIG. 6 is a schematic diagram showing a drive system of a conventional series hybrid electric vehicle.

[Explanation of symbols]

 2 motor 10 battery 16 generator 18 small engine 20 ammeter (charge / discharge detection means) 22 remaining capacity calculator 24 charge controller (control means) 26 oscillator circuit 28 temperature sensor (charge capacity detection means) 30 switching circuit (switching means) ) 36 capacitors

Claims (8)

[Claims] 1. A charge control device for a hybrid electric vehicle, comprising: driving a generator by an internal combustion engine to charge a battery; discharging the charged electricity to drive a motor; A charging / discharging detection means for detecting a discharging state, a switching means capable of periodically changing the charging current of the battery, and a charging / discharging detection means at least when the battery detects that the battery is in the charging state, And a control unit that intermittently supplies a charging current to the battery by a switching unit. 2. A charge control device for a hybrid electric vehicle, comprising: driving a generator by an internal combustion engine to charge a battery; discharging the charged electricity to drive a motor; A charging / discharging detection unit that detects a discharge state, a switching unit that can periodically change a charging current of the battery, a connection circuit between the battery and the motor, which is provided in parallel with the battery, and can store electricity. A capacitor, and a control unit that intermittently supplies a charging current to the battery by the switching unit when the charging / discharging detection unit detects that at least the battery is in the charging state. Charge control device. 3. The charge control device according to claim 1, wherein the charge state is a state in which the generator is driven by the internal combustion engine to charge the battery. 4. The charge control device according to claim 1, wherein the charge state is a regenerative state in which the motor generates power to charge the battery. 5. The charge control device according to claim 1, wherein the switching circuit has a discharging unit that constantly discharges a discharge current from the battery to the motor. 6. The charge control device according to claim 1, wherein the discharging state is a powering state in which the motor is driven by being supplied with electric power from the battery. 7. The charging / disconnecting ratio setting means for setting a connecting / disconnecting time ratio between the charging current and the discharging current according to the charging capacity, the charging capacity detecting means detecting the charging capacity of the battery. The charging control device according to claim 1 or 2, further comprising: 8. The charging control device according to claim 7, wherein the charging capacity detecting means includes a temperature detecting means for detecting the temperature of the battery.