JP2007191088A - Hybrid vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hybrid vehicle that can cope with the case of sudden starts and sudden stops. <P>SOLUTION: A hybrid vehicle, equipped with an engine 3 and a motor generator 5 as a power source for driving wheels, is provided with an electric double-layer capacitor 11 and a secondary battery 12 as the power source of the motor generator 5 and a first motor acceleration control means for interrupting the secondary battery 12, at the start acceleration of a vehicle, and for supplying the power of the electric double-layer capacitor 11 to the motor generator 5. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an improvement of a hybrid vehicle including an engine and a motor generator as a power source for driving wheels.

  Conventionally, as this type of hybrid vehicle, power is supplied to the motor generator to assist the engine output during vehicle acceleration, fuel supply to the engine is stopped during deceleration and braking, and the motor generator is operated as a generator. In some cases, regenerative braking is performed to charge the power storage device with the generated electric power.

The hybrid vehicle disclosed in Patent Document 3 includes a capacitor, a secondary battery, and a fuel cell as a power storage device.
Japanese Patent Laid-Open No. 11-224699 JP 2002-134125 A JP 2004-248433 A

  However, in such a conventional hybrid vehicle, when a secondary battery such as lithium ion or nickel metal hydride is used as a storage battery, a large current generated when the vehicle suddenly stops cannot be sufficiently absorbed. In addition, there is a problem that a large current necessary for sudden start cannot be sufficiently supplied.

  In addition, when an electric double layer capacitor is used as a storage battery, it can cope with a current flowing in and out of the vehicle at the time of sudden start and stop, but there is a problem that it is difficult to secure sufficient power storage.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a hybrid vehicle that can cope with sudden start and sudden stop.

  In the present invention, in a hybrid vehicle including an engine and a motor generator as a power source for driving wheels, an electric double layer capacitor and a secondary battery are provided as power sources for the motor generator, and the secondary battery is shut off when the vehicle is accelerated. First motor acceleration control means for supplying the electric power of the double layer capacitor to the motor generator is provided.

  According to the present invention, by using an electric double layer capacitor having a larger discharge power than the secondary battery at the time of starting acceleration, energy required for starting acceleration can be secured, and the secondary battery can be prevented from being rapidly discharged. Deterioration of the secondary battery can be suppressed.

  Embodiments of the present invention will be described with reference to the accompanying drawings.

  As shown in FIG. 1, the power train of a hybrid vehicle includes an engine 3 and a motor generator 5 as power sources, and the output of the engine 3 is transmitted to a drive shaft 4 via a transmission 6 and an engine side clutch 1, while the motor The output of the generator 5 is transmitted to the drive shaft 4 via the motor side clutch 2, and the rotation of the drive shaft 4 is transmitted to a wheel (not shown).

  The engine burns fuel and generates an output. For example, a spark ignition engine that burns gasoline or gas fuel, a diesel engine, or the like is used.

  The motor generator 5 is an AC machine such as a three-phase synchronous motor or a three-phase induction motor. The direct current stored in the power storage unit 10 is converted into alternating current power via an inverter (rectifier) 13 and supplied to the motor generator 5, and the alternating current generated power of the motor generator 5 is converted into direct current power to the power storage unit 10. Charge.

  An electric double layer capacitor 11 and a secondary battery 12 are provided as a power storage unit 10 that stores electric power supplied to the motor generator 5.

  As the secondary battery 12, various storage batteries using chemical reactions such as lithium ions and nickel metal hydride are used.

  The electric double layer capacitor 11 stores or discharges electric charges (electric energy) by electrostatic capacity, and increases the storage capacity by utilizing an interface phenomenon. The electric double layer capacitor 11 has a smaller storage capacity than the secondary battery 12, but inputs and outputs a larger current than the secondary battery 12.

  The power storage unit 10 includes first and second power storage circuits 14 and 15 connected in parallel to the motor generator 5 via an inverter 13, and the first and second power storage circuits 14 and 15 are provided with electric double layer capacitors. 11 and a secondary battery 12 are provided, and first and second switches SWc and SWb for opening and closing the first and second power storage circuits 14 and 15 are provided.

  The first and second switches SWc and SWb use field effect transistors (FETs), which are turned on when an applied voltage is led to each gate electrode, and close the first and second power storage circuits 14 and 15, respectively. If the applied voltage is not guided to the electrodes, the first and second power storage circuits 14 and 15 are opened respectively.

  The vehicle includes a controller 20 that controls the operation of the power train. The controller 20 inputs a vehicle speed signal, a brake signal, an accelerator signal, a secondary battery voltage Eb of the secondary battery 12, and a capacitor voltage Ec of the electric double layer capacitor 11. The engine side clutch 1, motor side clutch 2, inverter 13 The first and second switches SWc and SWb, the transmission 6 and the operation of the engine 3 are controlled.

  The vehicle is provided with a position sensor or the like that detects the amount of depression of a brake pedal (not shown), and outputs the brake signal corresponding to the amount of depression of the brake pedal (required braking force) operated by the driver.

  The vehicle is provided with a position sensor or the like that detects a depression amount of an accelerator pedal (not shown), and the accelerator signal corresponding to the depression amount (required load) of the accelerator pedal operated by the driver is output from the position sensor.

  The controller 20 transmits / receives information to / from an engine control controller (not shown) via a communication line and performs cooperative control with each other.

  The controller 20 performs motor travel control for driving the motor generator 5 in a state where the operation of the engine 3 is stopped and the clutch 1 is disengaged when the vehicle starts and travels at a low speed.

  The controller 20 controls the power supply of the electric double layer capacitor 11 to the motor generator 5 as the first motor acceleration control means by cutting off the secondary battery 12 when the vehicle starts to accelerate.

  Thus, by using the electric double layer capacitor 11 having a discharge power larger than that of the secondary battery 12 at the time of starting acceleration, it is possible to secure energy necessary for starting acceleration and avoid causing the secondary battery 12 to discharge rapidly, Degradation of the secondary battery 12 can be suppressed.

  The controller 20 determines, as the second motor acceleration control means, a capacitor potential lowering state in which the storage voltage Ec of the electric double layer capacitor 11 is lower than the storage voltage Eb of the secondary battery 12 when the vehicle is accelerated. In addition to the power of the electric double layer capacitor 11, the power of the secondary battery 12 is controlled to be supplied to the motor generator 5.

  Thereby, the acceleration travel distance by the motor generator 5 can be extended by the discharge power of the secondary battery 12.

  Next, the control operation at the time of start acceleration of the vehicle executed by the controller 20 will be described in more detail with reference to the flowchart of FIG.

  First, when the capacitor voltage Ec of the electric double layer capacitor 11 is lower than the secondary battery voltage Eb of the secondary battery 12 in step 1, the process proceeds to step 2 to turn on the first switch SWc and the second switch SWb, respectively. The electric double layer capacitor 11 is charged from 12.

  Since it is desired to use the energy of the electric double layer capacitor 11 at the time of starting acceleration, it is desirable that the electric double layer capacitor 11 has a higher potential than that of the secondary battery 12. It is conceivable that the potential of the capacitor 11 is low.

  In response to this, if the capacitor potential is lowered when the vehicle is stopped before starting, the secondary battery 12 is turned on by turning on the first switch SWc and the second switch SWb in the steps 1 and 2, respectively. To the electric double layer capacitor 11 through the second switch SWb and the first switch SWc.

  Even if the second switch SWb is turned off, the electric double layer capacitor 11 can be charged through the parasitic diode Dc, but the capacitor voltage Ec is reduced by the forward voltage drop (Eb) of the parasitic diode Dc.

  If it is determined in step 3 that the accelerator pedal is depressed based on the accelerator signal in the electric double layer capacitor charged state in which the capacitor voltage Ec is higher than the secondary battery voltage Eb, the process proceeds to step 4 and the second The switch SWb is turned off, the first switch SWc is turned on, and the routine proceeds to step 5 where the motor side clutch 2 is connected.

  Then, the process proceeds to subsequent steps 6 to 8 where the first motor acceleration control for driving the motor generator 5 by the output of only the electric double layer capacitor 11 is performed.

  In this first motor acceleration control, the inverter 13 is turned on in step 6 and the motor generator 5 is turned on until the vehicle speed has reached the required vehicle speed in step 7, and the output of the electric double layer capacitor 11 is turned on. Travel by.

  When the first motor acceleration control is performed, if it is determined in step 8 that the capacitor voltage Ec is lower than the secondary battery voltage Eb before the vehicle speed reaches the required vehicle speed, the following steps 9 and 10 are performed. Then, the second motor acceleration control for driving the motor generator 5 by the outputs of both the electric double layer capacitor 11 and the secondary battery 12 is performed.

  In this second motor acceleration control, the first switch SWc and the second switch SWb are turned ON until it is determined in step 10 that the vehicle speed has reached the required vehicle speed, and the electric double layer capacitor 11 and the secondary battery 12 are turned on. Travel by output.

  When the capacitor voltage Ec is lower than the secondary battery voltage Eb at the time of starting and the secondary battery 12 is charged to the electric double layer capacitor 11, the process proceeds to step 9 without going through the loop from step 8 to step 7. . In this case, a large current accompanying acceleration from speed 0 is required, but since the internal resistance of the electric double layer capacitor 11 is smaller than the internal resistance of the secondary battery 12, the current from the electric double layer capacitor 11 is exclusively generated by the motor generator. 5 and the load on the secondary battery 12 is reduced.

  On the other hand, if it is determined in step 3 that the accelerator pedal is depressed based on the accelerator signal, a starter motor (not shown) is driven in steps 12 and 13 to start the engine 3. When the vehicle speed reaches the required vehicle speed by the above-described first and second motor acceleration control, the routine proceeds to step 13 where the engine side clutch 1 is connected, the motor side clutch 2 is disconnected and the engine is switched to engine running (control 1).

  If the secondary battery voltage Eb and capacitor pressure Ec drop below the use limit values in step 11 before the vehicle speed reaches the required vehicle speed, the motor output clutch 2 is disconnected and the engine clutch 1 is connected to the half clutch to output the engine. (Control 2).

Incidentally, the determination of the capacitor potential drop which is carried out in step 1, 8, or capacitor voltage Ec is the secondary battery voltage Eb and the sum of the voltage drop E _D of the parasitic diode Db of the second switch SWb (Eb + E _D) below It is determined whether or not.

  The controller 20 also controls kinetic energy recovery (regeneration) during vehicle deceleration. As a high-current charging means that accompanies the braking of the vehicle, it is possible to control the secondary battery 12 to be cut off when the vehicle is braked and to charge only the electric double layer capacitor 11 with the electric power generated by the motor generator 5.

  By charging the electric double layer capacitor 11 having a larger current density than that of the secondary battery 12 with a large current accompanying braking, the energy during braking is efficiently absorbed, and rapid charging of the secondary battery 12 is avoided. Deterioration of the secondary battery 12 can be suppressed.

The controller 20 performs control to charge the secondary battery 12 while restricting electric power when the generated current due to braking energy cannot be absorbed by the high-speed charging.
As power limiting charging means, control is performed so that the electric double layer capacitor 11 and the secondary battery 12 are charged with the power generated by the motor generator 5 during braking of the vehicle, and the power charged in the secondary battery 12 is limited.

  As a result, a large current generated in a short time during sudden braking can be charged to the electric double layer capacitor 11 and the secondary battery 12, and the regeneration efficiency can be improved.

  Next, the charging control operation when the vehicle is running performed by the controller 20 will be described in more detail with reference to the flowchart of FIG.

  First, when it is determined in step 21 that the accelerator pedal has been returned to the initial position based on the accelerator signal, the routine proceeds to step 22 where it is determined whether or not the brake is being depressed based on the brake signal.

  If it is determined in step 22 that the vehicle is not braked, the motor-side clutch 2 is connected in step 23 for charging the secondary battery 12 with a low current, the first switch SWc is turned off in step 24, and the second switch SWb is turned on. Is turned ON, the rectifier of the inverter 13 is turned ON with a low efficiency, and the secondary battery 12 is charged with a low current in Step 25.

  When it is determined in step 26 that the secondary battery 12 has been fully charged, the process proceeds to step 27 where the second switch SWb is turned off, the rectifier of the inverter 13 is turned off, the motor side clutch 2 is turned off, The low current charging to the secondary battery 12 is terminated.

  If it is determined in step 22 that braking is in progress, the process proceeds to step 28 to determine whether the required braking force is greater than a predetermined value. This predetermined value is a value determined in advance so that braking energy can be recovered only by the electric double layer capacitor 11.

  If it is determined in step 28 that the required braking force is not more than the predetermined value, the process proceeds to step 29 where the motor side clutch 2 is connected, and in step 30, the first switch SWc is turned on and the second switch SWb is turned off. Then, the rectifier of the inverter 13 is turned on, and the electric double layer capacitor 11 is charged in step 31. At this time, the conversion efficiency of the inverter 13 is high.

  If the vehicle speed has fallen to such an extent that power generation by the motor generator 5 cannot be maintained, the engine side clutch 1 is connected at step 32 and stopped by the normal brake at step 33.

  If it is determined in step 28 that the required braking force is greater than the predetermined value, the process proceeds to step 34 where the engine side clutch 1 and the motor side clutch 2 are connected, and in step 35, the first switch SWc is turned on. Then, a pulse signal is input to the gate of the second switch SWb to turn it on intermittently, and the rectifier of the inverter 13 is turned on. In this state, in step 36, the electric double layer capacitor 11 is charged with a high current, and the secondary battery 12 is charged with a low speed depending on the pulse signal.

  In step 37, a brake (not shown) is actuated to apply a braking force exceeding the chargeable energy to the electric double layer capacitor 11 and the secondary battery 12.

  When stopping the vehicle, the routine proceeds to step 32 where the engine side clutch 1 is connected, and the routine proceeds to step 33 where a brake (not shown) is operated.

  Next, the operation and effect will be described.

  In a hybrid vehicle including an engine 3 and a motor generator 5 as power sources for driving wheels, an electric double layer capacitor 11 and a secondary battery 12 are provided as power sources for the motor generator 5, the secondary battery 12 is shut off, and an electric double layer is provided. Since the first motor acceleration control means for supplying the electric power of the capacitor 11 to the motor generator 5 is provided, a large current is required particularly in a short time by using the electric double layer capacitor 11 having a higher current density than the secondary battery 12 at the time of starting acceleration. In addition to supplying necessary energy to the motor generator 5 during starting acceleration, the secondary battery 12 can be prevented from being rapidly discharged, and deterioration of the secondary battery 12 can be suppressed.

  It is determined that the storage voltage Ec of the electric double layer capacitor 11 is lower than the storage voltage Eb of the secondary battery 12 during acceleration of the vehicle, and the electric power of the secondary battery 12 is added to the electric power of the electric double layer capacitor 11 in the motor generator 5. Since the second motor acceleration control means for supplying to the battery is provided, the acceleration travel distance by the motor generator 5 can be extended by the discharge power of the secondary battery 12.

  Since the secondary battery 12 is cut off and the high current charging means for charging only the electric double layer capacitor 11 with the electric power generated by the motor generator 5 is provided, the electric double layer capacitor 11 is rapidly charged with a large current generated during braking of the vehicle. In addition, the secondary battery 12 can be prevented from being rapidly charged and deterioration of the secondary battery 12 can be suppressed.

  Since the electric double layer capacitor 11 is rapidly charged with the electric power generated by the motor generator 5 during braking of the vehicle and at the same time the electric power charged in the secondary battery 12 is limited, the electric power is limited. The regenerative efficiency is improved by adding the charging power of the secondary battery 12 to the charging power of the multilayer capacitor 11.

  The present invention is not limited to the above-described embodiment, and it is obvious that various modifications can be made within the scope of the technical idea.

1 is a system diagram of a hybrid vehicle showing an embodiment of the present invention. The flowchart which similarly shows the control action at the time of start acceleration of a vehicle. The flowchart which shows the control operation which charges similarly at the time of driving | running | working of a vehicle.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine side clutch 2 Motor side clutch 3 Engine 5 Motor generator 11 Electric double layer capacitor 12 Secondary battery 13 Inverter SWc 1st switch SWb 2nd switch

Claims (4)

In a hybrid vehicle including an engine and a motor generator as a power source for driving wheels,
An electric double layer capacitor and a secondary battery as a power source of the motor generator;
A hybrid vehicle comprising first motor acceleration control means for cutting off the secondary battery and supplying electric power of the electric double layer capacitor to the motor generator during acceleration of starting of the vehicle.   When the vehicle is accelerated, a capacitor potential lowering state in which the storage voltage Ec of the electric double layer capacitor is lower than the storage voltage Eb of the secondary battery is determined, and in addition to the electric power of the electric double layer capacitor in the capacitor potential lowering state, The hybrid vehicle according to claim 1, further comprising second motor acceleration control means for supplying electric power of a secondary battery to the motor generator.   3. The hybrid vehicle according to claim 1, further comprising a high-current charging unit that shuts off the secondary battery and charges the electric double layer capacitor with electric power generated by the motor generator during braking of the vehicle.   A power limiting charging means is provided for charging the electric double layer capacitor and the secondary battery with electric power generated by the motor generator during braking of the vehicle, and limiting the electric power charged in the secondary battery. Item 4. The hybrid vehicle according to any one of Items 1 to 3.

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