JP3465293B2 - Vehicle power control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for regenerating electric power generated by a vehicle generator to a standby power storage means by utilizing vehicle kinetic energy at the time of deceleration. The present invention relates to a vehicular power control device for improving fuel efficiency by reducing the amount of power generated by a vehicular generator except during deceleration by extracting power from the reserve power storage means. 2. Description of the Related Art A vehicular generator is connected to an engine, and its rotation speed varies over a wide range. Therefore, a regulator for controlling a generated voltage to a predetermined value is provided. The regulator normally turns on and off the field current of the vehicle generator
The generator voltage is controlled by causing the generator to generate power intermittently, and when the load on the generator increases, the power generation time is extended to maintain the generated voltage constant. By the way, electric components of vehicles have been rapidly increasing in recent years, and accordingly, vehicle generators have been increasing in size. In addition, a large-capacity vehicle generator imposes a heavy load on the engine during power generation, impairing the acceleration performance of the vehicle. On the other hand, when the vehicle is decelerated, it is preferable to generate power positively to promote braking of the engine, and to regenerate wastefully dissipated energy to the battery. However, the usage status of electrical components fluctuates day or night or seasonally, and if the power generation time is forcibly shortened for acceleration, the battery overload occurs when the load on the so-called generator that uses a lot of electrical components is large. This causes discharge and lamp flickering. On the other hand, if the electrical components are not used and the load on the generator is small, and the power generation time is forcibly extended during deceleration, the battery will be overcharged or the lamp will run out. Therefore, the power generation time is shortened only when the vehicle is accelerating and the load on the generator is small,
There is a demand for a regulator that extends the power generation time only when the vehicle is decelerating and when the load on the generator is large. JP-A-59-106900 discloses that the acceleration state of a vehicle is detected by the amount of change in the number of revolutions of the generator, and the load state of the generator is detected from the conductivity of a switching element for controlling the field winding current. Another object of the present invention is to provide a regulator that appropriately controls the power generation time by generating a set value of a generator output voltage according to a running state of a vehicle and a load state of the generator. However, when the vehicle is decelerating and the load is large, the regenerative electric power is stored in the battery by increasing the set voltage of the regulator, and when the vehicle is accelerating and the load is small. In a vehicle generator control device that reduces the set voltage and reduces the output of the vehicle generator to reduce the load on the generator and improve fuel efficiency, the fluctuation of the battery voltage increases and the deceleration is performed with the generator load small. If the set voltage is increased, the main power storage means may run out of liquid or the lamp may be cut off due to overcharging. On the other hand, when the set voltage is lowered by accelerating while the generator load is large,
Lamp flickering occurs due to an increase in voltage fluctuation due to overdischarge of the battery or a decrease in the regulator ON time. In addition, the main power storage means that is fully charged has a low power density during charging, and thus cannot efficiently store regenerative power during deceleration. The present invention has been made in order to solve the above-mentioned problem, and has a main power storage means by providing a standby power storage means and temporarily storing regenerative electric power in the standby power storage means at the time of deceleration and discharging the power at times other than the time of deceleration. It is an object of the present invention to provide a power control device for a vehicle which has a small voltage fluctuation, has no overcharge or overdischarge, and can efficiently store regenerative power during deceleration. [0004] The present invention provides a vehicle power supply including a vehicle generator driven by a driving engine and a main power storage means, as specific means for solving the above problems. A standby power storage means, a bidirectionally switchable connectable DC-DC converter connected between the vehicle power supply and the standby power storage means, and a bidirectional voltage conversion; The DC power source is charged so that the standby power storage device is charged and the charged power is discharged prior to the main power storage device and supplied to the vehicle electric load except during deceleration.
A power control device for a vehicle, comprising: an electronic arithmetic device that controls switching of the DC converter. According to the power control device for a vehicle having the above configuration, the DC-DC converter is switched by the electronic arithmetic device so that the regenerative power obtained at the time of deceleration is stored in the standby power storage means. In addition, at the time of acceleration other than deceleration, at the time of constant speed running, and in the idling state, etc., the electric power charged in the standby power storage means is supplied to the vehicle electric load with priority over the main power storage means, and in other cases, The power is supplied to the vehicle electric load by the generator and the main power storage means, and the power by the generator is stored in the main power storage means. An embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a configuration diagram of a vehicle power control device. A battery 1 serving as a main power storage unit charges electric power generated by an alternator 3 serving as a vehicle generator and discharges and supplies the electric power to a vehicle electric load 2. When the voltage generated by the alternator 3 is lower than the charging voltage of the battery 1 such as when the engine 8 is stopped or started, the battery 1 supplies the electric load 2 with the power generated by the battery 1 by a chemical action. The voltage of the alternator 3 when the battery 1 can be charged is usually 13V to 15V. A regulator and a rectifier (not shown) are built in the alternator 3, and the regulator turns on and off a field current flowing through the rotor of the alternator 3, and applies a voltage of 13 V to the stator.
A three-phase AC voltage of 15 V is generated, and the rectifier rectifies the AC voltage of the stator to DC. The electric load 2 is an electric device that consumes power, such as various lamps such as a headlight, a hazard lamp, and a flasher, and various devices such as a starter, an air conditioner, a wiper, and a radio. The alternator 3 is connected to the engine 8 and is driven by the engine 8 when idling, accelerating, and traveling at a constant speed. However, the throttle valve is fully closed when the vehicle decelerates. Is driven through. The DC-DC converter 4 is a device for switching and controlling the charging and discharging of the electric double layer capacitor 7 serving as a reserve power storage means. For example, a DC-AC exchanger on the low voltage side, a transformer, a rectifier , A one-way diode, and a changeover electronic switch. The electronic switch is switched by the ECU 5 serving as an electronic arithmetic unit to charge and discharge the standby power storage unit 7. E
The CU 5 performs an operation on the signal receiving terminal 6 when idling, accelerating, running at a constant speed, decelerating, stopping the engine 8, and detecting a voltage signal of the battery 1. Then, a switching control signal is sent to the DC-DC converter 4 based on the calculation result. The electric double-layer capacitor (hereinafter referred to as electric double-layer capacitor 7) constituting the preliminary storage means 7 is a capacitor using an electric double layer generated at an interface between a solid and a liquid, and uses activated carbon having a large surface area per unit volume as a solid. The capacity is increased by using dilute sulfuric acid as the liquid. Therefore, the capacity is several thousand times or more as large as that of a general capacitor. And DC-DC
The switching control by the converter 4 performs charging of regenerative power or supply of power to the vehicle electric load 2. First, an outline of the operation of the vehicle power control device having the above configuration will be described. When the ECU 5 detects the deceleration running based on the input signal to the signal receiving terminal 6, the ECU 5 detects whether the battery voltage (Vbat) of the battery 1 is at a certain level (for example, 13V). When the battery voltage is equal to or higher than a certain level, the DC-DC converter 4 is controlled to charge the electric double layer capacitor 7 at a constant current up to its withstand voltage level. In addition, when the vehicle is accelerating, decelerating, and idling other than during deceleration, the ECU
Reference numeral 5 controls the DC-DC converter 4 to discharge the electric double layer capacitor 7 so as to supply a current of about 10 A required for a normal electric load of the vehicle to the electric load 2 of the vehicle. In this case, to prevent the battery 1 from being overcharged, for example, when the battery voltage is 15 V or more, the electric double layer capacitor 7 does not discharge. Next, the operation of the vehicular power control device having the above configuration will be described with reference to the flowchart shown in FIG. FIG. 2 shows a main program P1 in the ECU 5.
FIG. When the engine is started, the alternator 3 continues to output a constant voltage under the control of the regulator. Then, in step S110, it is determined whether or not the vehicle is in the idling state based on the input signal of the signal receiving terminal 6. If the vehicle is in the idling state, in step S111, if the battery voltage is 15 V or less, the DC-DC converter 4 is switched, and a current of about 10 A required for a normal electric load of the vehicle is supplied from the electric double layer capacitor 7 to the electric load 2 of the vehicle. When the battery voltage exceeds 15 V, the electric double layer capacitor 7 does not discharge so that the battery 1 is not overcharged, so that the electric power is supplied to the vehicle electric load 2 by the alternator 3 or the battery 1. Then, during acceleration traveling (steps S120 to S121) and at constant speed traveling (step S120).
Also in 130 to S131), the determination and processing according to the battery voltage similar to the idling state (steps S110 to S111) are performed. And step S
When the deceleration traveling is confirmed by the input signal of the signal receiving terminal 6 in 140, if the battery voltage is 13V or more in step S141, the DC-DC converter 4 charges the electric double layer capacitor 7 to the withstand voltage.
Also, in step S141, the battery voltage becomes 13V.
Is less than, the battery 1 is charged. Next, in step S150, it is determined whether or not the engine is stopped. If not, step S110 is performed.
If the program has stopped, the program ends in step S160. According to the above embodiment, by controlling the charging and discharging of the electric double layer capacitor 7 as described above, the amount of power generated by the alternator 3 exceeds the amount of power consumed by the vehicle electric load 2 when the battery 1 is full. In addition, since the surplus power in which the generated power cannot be completely regenerated in the battery 1 can be used when the battery 1 is not full and the alternator 3 does not have sufficient power generation, there is no waste of power, and the alternator 3 generates power. The fuel consumption of the engine can be improved by reducing the amount. In addition, since the regulated voltage of the regulator is always constant irrespective of the traveling state, unlike the method of charging the battery 1 by increasing the regulated voltage of the regulator significantly during deceleration traveling, the voltage fluctuation of the battery 1 is small and the No flickering occurs. Further, since the number of times of charging and discharging of the main power storage means can be reduced, the life of the main power storage means can be extended. Also, the DC-DC converter 4, the ECU
5 and the electric double layer capacitor 7 are formed into one package, and if the vehicle deceleration signal is detected by a brake lamp, it can be easily mounted on vehicles already sold and on the market. Further, in the case of a vehicle using injection, which performs fuel cut at the time of deceleration, if a deceleration signal is detected from the fuel cut signal,
Only during deceleration traveling can be detected more accurately, and electric power can be regenerated more effectively. Next, as another embodiment, an embodiment in which the present invention is applied for the purpose of suppressing rotation fluctuation caused by repetition of combustion and compression of the engine during idling will be described.
This will be described based on a flowchart. Since the rotation of the engine is repeatedly accelerated in the combustion stroke and decelerated in the compression stroke, there is a rotation fluctuation of about several tens rpm even during idling. This rotation fluctuation during idling causes the lamps to flicker and the tachometer pointer to quiver. Further, since irregular vibrations are generated, which gives a passenger an unpleasant sensation. It is important to suppress the rotation fluctuation during idling in order to enhance the quality of the vehicle. FIG. 3 is a flowchart showing a program P200 for controlling the rotation fluctuation. If the tendency of the engine speed to increase due to combustion is detected in step S210, D is determined in step S211.
The switching of the C-DC converter 4 is controlled to charge the electric double layer capacitor 7. Therefore, the electric double layer capacitor 7
, The electric load of the alternator 3 is increased, and an increase in the engine speed can be suppressed. If a tendency of the engine speed to decrease due to compression is detected in step S220,
Conversely, in step S221, the DC-DC converter 4 is switch-controlled to supply the electric power of the electric double layer capacitor 7 to the vehicle electric load 2. Therefore, it is possible to reduce the electric load of the alternator 3 and suppress a decrease in the engine speed. By repeating the above two operations, rotation fluctuations during idling can be suppressed and rotation can be stabilized. Therefore, it is possible to eliminate the fluctuation of the output voltage of the alternator 3 due to the rotation fluctuation, the flickering of the lamps and the unpleasant engine vibration accompanying the fluctuation. An embodiment in which the present invention is applied to suppress fluctuations in engine speed due to use of an intermittent electric load such as a hazard and stabilize engine rotation will be described with reference to a flowchart P300 shown in FIG. If an intermittent electric load such as a hazard is used during idling,
The engine speed becomes 50 due to the load fluctuation of the alternator 3.
It fluctuates by about rpm. In this case, when the ON of the intermittent electric load (hazard or the like is lit) is detected in step S310, a part of the power required by the intermittent electric load is switched from the DC-DC converter 4 to the electric double layer capacitor 7 in step S311. In this way, the load originally applied to the alternator 3 is compensated. Step S3
When the intermittent electric load is turned off (hazard or the like is turned off) at 20, the power consumed by the intermittent electric load is switched by the DC-DC converter 4 so that the electric double layer capacitor 7 stores the electric power. By repeating the above two operations, the electric load of the alternator 1 when the intermittent electric load is used can be made constant, and the rotation fluctuation of the engine can be suppressed and the rotation can be stabilized. Therefore, similarly to the case of suppressing the rotation fluctuation caused by the repetition of the combustion and the compression described above, the pulsation due to the intermittent electric load of the output voltage of the alternator 3 due to the rotation fluctuation is eliminated, the lamps flicker when the intermittent load is used, the meter There is an effect that panel flickering and unpleasant engine vibration can be eliminated. The power control device for a vehicle according to the present invention has the above-described configuration, and by providing the reserve power storage means, the regenerative power during deceleration is temporarily stored in the reserve power storage means. By discharging, the fluctuation of the voltage of the main power storage means is small, there is no overcharge or overdischarge, and regenerative power during deceleration can be stored efficiently.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram showing the overall configuration of the present invention. FIG. 2 is a flowchart showing the operation of the embodiment of the present invention. FIG. 3 is a flowchart showing an embodiment in which the present invention is applied to stabilization of the engine speed during idling. FIG. 4 is a flowchart showing an embodiment in which the present invention is applied to voltage stabilization when an intermittent electric load is used during idling. [Explanation of Signs] 1. Main power storage means (battery) 2. Vehicle electric load
3. Vehicle generator (alternator), 4 .. DC
-DC converter, 5 ... electronic arithmetic unit (ECU),
6 ... Signal receiving terminal 7 ... Preliminary storage means (electric double layer capacitor) 8. Engine, 9 ... Tires, P100 to P300 ... Program, S110
~ S340 ... step

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-271209 (JP, A) JP-A-2-206301 (JP, A) JP-A-2-206302 (JP, A) JP-A-3-206 538 (JP, A) JP-A-54-149112 (JP, A) JP-A-51-32926 (JP, A) JP-A-5-44518 (JP, A) JP-A-5-161280 (JP, A) JP-A-3-74146 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02J ⁷ /00-7/34 H02J 1/00 B60L 11/18 B60R 16/02

Claims (1)

(57) [Claim 1] A vehicle power source including a vehicle generator driven by a traveling engine and a main power storage unit, a standby power storage unit, the vehicle power source and the standby power storage unit A DC-DC converter switchable between two directions and connectable and capable of voltage conversion, detecting a running state of the vehicle, charging the standby power storage means during deceleration, and supplying the charged power except during deceleration. And an electronic arithmetic unit for controlling the switching of the DC-DC converter so that the DC-DC converter is discharged with higher priority than the main power storage means and supplied to the vehicle electric load.