JP3180304B2 - Power circuit of hybrid car - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply circuit of a hybrid vehicle, and more particularly, to a power supply circuit of a hybrid vehicle for efficiently driving an engine.

[0002]

2. Description of the Related Art Electric vehicles are being actively developed and put into practical use from the viewpoint of environmental protection. In this electric car,
A vehicle is driven by driving a motor with electric power of a battery. However, since the capacity of the battery has a certain limit, a hybrid vehicle equipped with an engine and a motor has been developed in order to extend the traveling distance. This hybrid car has
There are two types: a parallel type, which uses an engine as a vehicle driving force source to reduce battery consumption, and a serial type, which drives a generator with the engine to generate power and charges the battery to increase the amount of battery that can be consumed. Exists. Since a hybrid vehicle has an engine, it is necessary to reduce the generation of exhaust gas by the engine as much as possible. Such a technique is disclosed in Japanese Patent Application Laid-Open No. S51-3981.
There is a hybrid vehicle described in Japanese Patent No. In this hybrid vehicle, the engine is operated at a constant rotational speed regardless of the load, the generator generates power, the battery is charged, and when the battery is fully charged, the engine is automatically stopped. As described above, the output of the engine generator is controlled to be substantially constant electrically, and the variation is applied to the battery to improve the combustion efficiency of the engine, thereby achieving low pollution and saving fuel.

[0003]

FIG. 6 shows the relationship between the engine output and the amount of battery B chargeable to the battery 17 with respect to the engine speed Ne and the engine torque Te. As shown in FIG. 6, the amount of power generated by the engine at the highest efficiency point is the amount of chargeable battery B [K
w], the battery deteriorates in the above-mentioned conventional hybrid vehicle. On the other hand, if the engine 17 is driven at a point lower than the maximum efficiency point in order to suppress the deterioration of the battery 17, that is, at a point where one or both of the torque and the rotational speed are lowered, the fuel efficiency of the engine 17 is reduced and the exhaust gas is reduced. Emissions increase.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a power supply circuit for a hybrid vehicle capable of driving an engine near a maximum efficiency point to reduce exhaust gas and prevent battery deterioration.

[0005]

According to the first aspect of the present invention, an engine, a capacitor and a battery for storing electric power, a detecting means for detecting a charge amount stored in the battery, and a driving state of the vehicle are detected. Running state detecting means, and an engine driving means for driving the engine in the vicinity of the highest efficiency point, when the detecting means detects a charge amount equal to or less than a predetermined value and the running state detecting means detects a running stop state, A power generating means for generating power by driving the engine by the engine driving means and supplying the generated power to the capacitor; and a case where the running state detecting means detects the end of the running stop state, or the capacity of the capacitor is a predetermined value. An engine stopping means for stopping the operation of the engine when the battery is charged, and an electric power stored in the capacitor, Charging means for charging, by provided the city power supply circuit of the hybrid vehicle to achieve the above objectives.

[0006]

In the power supply circuit for a hybrid vehicle according to the first aspect, the charge amount stored in the battery is equal to or less than a predetermined value.
Is detected by the detecting means, and when the running stop state of the vehicle is detected by the running state detecting means, the engine is driven near the maximum efficiency point by the engine driving means, and power is generated by the power generating means.
The power generated by the power generation means is supplied to the capacitor, and the power stored in the capacitor is charged to the battery by the charging means. When the engine stops running,
Will be activated when the capacitor capacity is charged
The operation is stopped by the stop means.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a power supply circuit for a hybrid vehicle according to the present invention will be described below in detail with reference to FIGS. FIG. 1 shows a power supply circuit of a hybrid vehicle and its surroundings. In this embodiment, a serial hybrid vehicle in which the driving force of an engine is used only for driving a generator is shown. The power supply circuit 10 of the hybrid vehicle includes an engine 11 and a power generator 13. The power generation device 13 includes a rectification device (not shown), and rectifies and outputs power generated by driving the engine. The power supply circuit 10 of the hybrid vehicle includes a capacitor 15 and a battery 1.
7 to accumulate the electric power generated by the power generation device 13 . Capacitor 15 and battery 17 are connected in parallel to power generator 13 .
In addition, in order to charge the capacitor 15 and the battery 17,
A fuel cell (not shown) may be connected in parallel with these. Fuel cell capacitor 15 and battery 1
The charging of 7 is performed when the driving time of the engine 11 according to the present embodiment is short.

[0008] The capacitor 15 and the battery 17 are connected to a power amount detecting section 19 as detecting means, and the power amount and the charge amount are detected. Electric energy
The detection unit 19 includes a voltage sensor (not shown), and calculates the charge amount Q = the capacitance C × the voltage V by measuring the terminal voltage of the capacitor 15. Further, the terminal voltage of the battery 17 is measured, and a curve indicating the voltage and the capacity is obtained from the curve.
The battery capacity is derived.

The battery 17 includes a lead-acid battery, a nickel-cadmium battery, a sodium-sulfur battery, and a lithium-ion battery.
Various secondary batteries such as a secondary battery, a hydrogen secondary battery, and a redox battery are used. The battery 17 is configured to have a voltage of, for example, 240 [V] by connecting a plurality of secondary batteries in series or in series and parallel.

On the other hand, as the capacitor 15, for example,
An electric double layer capacitor using an electric double layer formed at the interface between the polarizing electrode and the electrolyte is used. This electric double layer capacitor is a capacitor having a large capacity per unit volume, a low resistance and a large output density, and the capacity is determined in consideration of the balance with the occupied volume. For example, a capacitor having a large capacity of 9F or more is used. The electric double layer capacitors are stacked in a plurality of stages so as to withstand the voltage of the power generated from the power generator 13.

[0011] The power supply circuit 10 of the hybrid vehicle also includes:
The control unit 21 functions as an engine driving unit. The control unit 21 drives the engine 11 near the maximum efficiency point in accordance with the electric energy of the capacitor 15 and the battery 17 supplied from the electric energy detection unit 19. Here, the highest efficiency point is a point at which the output (rotation speed × torque) with respect to the input (gasoline consumption) is the maximum. The control unit 21 includes the first and second switches 2
By controlling the connection and disconnection of 3, 25, it functions as a charging means, and controls charging of the capacitor 15 and the battery 17 from the power generator 13 . As the first and second switches 23 and 25, a contact switch such as a relay or a switch circuit including a logic circuit element such as a logical sum or a transistor is used. The first switch 23 is configured as a b-contact whose contact is opened during operation,
The switch 25 is configured as an a contact to which a contact is connected during operation.

The control section 21 is connected to a sensor section 27. The sensor unit 27 includes various sensors such as a shift lever sensor 271, an accelerator sensor 272, a brake sensor 273, and a speed sensor (not shown). Sensor part 2
7, a signal indicating the position of the shift lever 271;
Various signals such as an accelerator sensor 272 and a signal indicating the amount of depression of the brake are supplied to the control unit 21 as a motor command value. The control unit 21 functions as a traveling state detection unit together with the sensor unit 27 by detecting the traveling state of the vehicle based on the motor command value supplied from the sensor unit 27. The control unit 21 also determines the output of the motor 33 from the motor command value in response to a driver's traveling request by depressing an accelerator or a brake corresponding to the shift lever position. Then, a current signal S corresponding to the determined output of the motor 33 is supplied to the inverter 31. The inverter 31 drives the motor 33 by supplying a current according to the current control signal.

An inverter 31 is connected in parallel to the battery 17 in the power supply circuit 10 of the hybrid vehicle thus configured. The inverter 31 has, for example, a bridge circuit using a transistor and a diode, and a smoothing capacitor. The inverter 31 converts a direct current supplied from the battery 17 into a three-phase alternating current and outputs the three-phase alternating current to the motor 33. As the motor 33, for example, a DC brushless motor including a rotor composed of six-pole permanent magnets and an electromagnet coil composed of three-phase windings, that is, a stator coil is used.

Next, the operation of the embodiment configured as described above will be described. FIG. 2 illustrates a charging process operation by driving an engine by a power supply circuit of a hybrid vehicle. The control unit 21 constantly monitors the traveling state of the vehicle from the vehicle speed signal and the shift position signal supplied from the sensor unit 27, and constantly monitors whether or not the traveling is stopped (step 11). Here, the running stop state refers to the case where the ignition is ON, the side brake is applied, and the case where the shift lever is in the parking or neutral position and the vehicle speed is 0.

When the traveling stop state is detected (step 1)
1; Y), it is determined whether the battery charge is equal to or less than a predetermined value (step 12). That is, the power amount detection unit 19
The voltage of the battery 17 is measured from the voltage sensor and the control unit 21
To supply. The control unit 21 derives the charge amount of the battery 17 from the voltage-capacity curve. If the charge amount is not less than the predetermined value (step 12; N), the process returns. On the other hand, when the charge amount of the battery 17 is equal to or less than the predetermined value (Step 12; Y) , the control unit 21 drives the engine 11 near the maximum efficiency point A (Step 1).
3). When the engine is driven, power generation is started by the power generation device 13, and the power is charged in the capacitor 15.

The control section 21 monitors whether or not the capacity of the capacitor 15 has reached a predetermined value (substantially fully charged state) by charging the capacitor 15 (step 14).
If the value is equal to or less than the predetermined value (Step 14; N), the control unit determines whether or not the traveling stop state has ended based on the motor command value supplied from the sensor unit 27, that is, whether or not the vehicle has shifted to the traveling state. A decision is made (step 15). If the traveling stop state continues (step 15; Y), step 14
And charging is continued until the capacity of the capacitor becomes equal to or more than the predetermined value.

When the capacity of the capacitor 15 has been charged to a predetermined value or more (step 14; Y) and when the running stop state has been completed (step 15; N), the control unit 21
Stops the driving of the engine 11 (step 16). Next, the control unit 21 charges the battery 17 from the capacitor 15 by connecting the switch 25, and when the charging is completed, the control unit 21 returns the switch to the original state (step 17) and returns the process. .

As described above, in this embodiment, the drive of the engine 11 is intermittently controlled by turning on and off the drive, and when the engine 11 is on, the drive is always performed near the maximum efficiency point. And the amount of exhaust gas discharged can be kept low. In addition, since the configuration is such that the capacitor 15 and the battery 17 are provided and the power generated by the power generator 13 is charged in the capacitor 15,
The deterioration of the battery 17 can be prevented.

The switch 25 is opened during operation.
The power generated by the power generation device 13 is
5 and the battery 17 may be charged.
In this case, since the internal resistance of the capacitor 15 is lower than that of the battery 17, the capacitor 15 is mainly charged preferentially. Since the battery 17 is charged in a small amount, no deterioration occurs. In this way, by charging a part of the power generated by the power generating device 13 to the battery 17, the charging time for the capacitor 15, that is, the driving time of the engine 11 is reduced.
The number of times of turning on and off is reduced, and the fuel efficiency is further improved.

Next, a second embodiment will be described. First
In the embodiment, the engine 1 is stopped when the vehicle is stopped.
In the second embodiment, the engine 11 is controlled so as to be driven near the maximum efficiency point even when the vehicle is running. FIG. 3 shows the relationship between the generated power A ′ in the vicinity A of the highest efficiency point, the chargeable battery amount B ′, and the traveling power D required for running the vehicle, corresponding to FIG. . The battery 17 deteriorates when the actual charge capacity H = A'-D, which is obtained by subtracting the traveling power D used for driving the motor from the generated power A ', is larger than the battery amount B'. Therefore, in the second embodiment, the battery 17 is charged with the generated power A 'when the actual charge amount H≤the battery amount B'. In this case, the control unit 21 opens the first switch 23 and connects the second switch 25. On the other hand, the actual charge amount H
> In the case of battery amount B ', the generated power A'
5 and the battery 17 are charged. In this case, the control unit 21 connects the first and second switches 23 and 25 together. It should be noted that the actual charge amount H is
The running power D is calculated according to the motor command value supplied from the sensor unit 27, and the battery amount B ′ is calculated from the voltage of the battery 17 supplied from the power amount detecting unit 19.

FIG. 4 conceptually shows an example of the charged state of the actual charged amount H and states of the first and second switches 23 and 35 in each state. In FIG. 4, from the top, the on / off state E / G of the engine, the generated power A 'near the highest efficiency point A, and the amount of battery B' that can be charged downward with reference to the generated power A 'are shown. . The horizontal axis represents the time axis, and represents the curve D of the traveling power D used for driving the motor according to the traveling of the vehicle. In the running of the vehicle, it is assumed that the ignition is turned on at time t1, the acceleration / deceleration is repeated from time t2, and the running stop state is continued after time t6.

When such traveling is performed, first, at time t
When the ignition is turned on, the engine 11 is driven near the maximum efficiency point A, and the generated power A ′ is output from the power generator 13. Between the time t1 and the time t2, the actual charge amount H2> the battery amount B ′, so that the first and second charge amounts are obtained.
The switches 23 and 25 are connected (ON) to charge the battery 17 with the generated power A '(hatched portion) and also charge the capacitor 15 (dotted portion). At time t3, the traveling power D increases, and the actual charge amount H ≦
Since the battery amount becomes B ', the first switch 23 is opened (OFF) to charge only the battery 17. Time t4
Ｔt5, the traveling power D larger than the generated power A '
Therefore, by connecting both the first and second switches, the capacitor 15 and the battery 1 are connected.
Electric power is supplied from 7 to the motor 33 via the inverter 31.

As described above, the engine 11 is driven in the vicinity of the highest efficiency point A, and the first switch 23 is turned on and off by the change in the actual charge amount H accompanying the change in the warehouse power D.
The capacitor 15 and the battery 17 are charged. And
Even after the running is stopped at time t6, the engine 11 is driven near the maximum efficiency point A, and is turned off at time t7 when the capacity of the capacitor 15 becomes equal to or more than the predetermined amount. At this time, by connecting the first switch 23 without opening it, the battery 17 is charged with the charging power of the capacitor 15 thereafter. The control unit 21 also monitors the charge amount of the battery 17 and charges the battery 17 by a predetermined amount or more before the capacitor 15 as in the case where the traveling power D continues traveling in a region where only the battery is charged. If so, the engine 11 is turned off at that time.

In the embodiment described above, a serial type hybrid vehicle has been described. As shown in FIG.
The present invention can be applied to a parallel type hybrid vehicle. In this case, the engine 11 'is connected to the motor 33' via the clutch 41 and bears part or all of the driving force of the vehicle. And the motor 3
3 'is connected to the transmission 45 via the clutch 43, and when the clutch 43 is released, is rotated by the drive of the engine 11 and functions as a generator.

[0025]

As described above, according to the present invention,
The engine can be driven near the maximum efficiency point to reduce exhaust gas and prevent battery deterioration.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a power supply circuit of a serial-type hybrid vehicle according to an embodiment of the present invention, and its periphery.

FIG. 2 is an explanatory diagram showing a charging process operation by an engine driven by a power supply circuit of the hybrid vehicle.

FIG. 3 is a diagram showing the generated power A ′,
FIG. 5 is an explanatory diagram showing a relationship between a battery amount B ′ and a traveling power D.

FIG. 4 is an explanatory diagram conceptually showing an example of a charging state of an actual charging amount H and states of first and second switches 23 and 35 in each state in the second embodiment.

FIG. 5 is a circuit diagram showing a power supply circuit of a parallel-type hybrid vehicle used in another embodiment of the present invention and a periphery thereof.

FIG. 6 is an explanatory diagram showing a relationship between an engine output and an amount of battery B chargeable to a battery with respect to an engine speed Ne and an engine torque Te.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Power circuit of hybrid vehicle 11 Engine 13 Power generation device 15 Capacitor 17 Battery 19 Electric energy detection unit 21 Control unit 23 First switch 25 Second switch 27 Sensor unit 31 Inverter 33 Motor

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-55-157901 (JP, A) JP-A-4-271209 (JP, A) JP-A-51-39813 (JP, A) (58) Investigation Field (Int.Cl. ⁷ , DB name) B60L ⁷ /00-13/00 B60K 6/02 H02J 1/00 306 H02J 9/06 505

Claims (1)

(57) [Claims] An engine; a capacitor and a battery for storing electric power; a detecting means for detecting a charge amount stored in the battery; a running state detecting means for detecting a running state of the vehicle; An engine driving means for driving the engine in the vicinity of a maximum efficiency point when the traveling state detecting means detects a traveling stop state by detecting a charge amount equal to or less than a value, and generating electric power by driving the engine by the engine driving means. A power generation unit that supplies the generated power to the capacitor; and a drive of the engine when the end of the travel stop state is detected by the travel state detection unit or when the capacity of the capacitor is charged to a predetermined value or more. Engine stopping means for stopping power, and charging means for charging the battery with electric power stored in the capacitor. Hybrid car power supply circuit according to claim.