JP3691984B2 - Control device for hybrid vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce shock or vibration being generated in conversion to the extent that a crew does not feel uncomfortable by gradually increasing the current of an electric generator to a control target value with time lapse when converting from an electric mode to a generation mode. SOLUTION: When auxiliary acceleration is to be made with an electric generator 2 as an electric mode, a control circuit 5 reads the output of an accelerator sensor 17 that is linked to an acceleration pedal 21 to control an inverter circuit 4 so that a rotary magnetic field that is slightly larger (positive slippage rate: 0 to several %) than a rotary speed that is detected by a rotary sensor 6 can be generated in the field coil winding of the electric generator 2. At this time, electrical energy is supplied from a battery 3 to the electric generator 2. When auxiliary control is to be made with the electric generator 2 as a generation mode, a control circuit 5 controls the inverter circuit 4 so that a rotary magnetic field that is slightly smaller (negative slippage rate: 0 to several %) than the rotary speed that is detected by the rotary sensor 6 can be generated in the field coil winding of the electric generator 2. At this time, energy can be supplied from the electric generator 2 to the battery 3.

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is applied to a hybrid vehicle including an internal combustion engine that drives an axle and a motor generator that performs auxiliary acceleration and auxiliary braking thereof. The present invention relates to an improvement for mitigating shock or vibration that occurs when a motor generator switches between an electric mode in which auxiliary acceleration is performed and a power generation mode in which electric braking is performed.
[0002]
The present invention was developed as a control device suitable for a hybrid vehicle for buses or trucks manufactured and sold by the applicant under the name of HIMR and disclosed in International Publication No. WO88 / 06107 (International Application No. PCT / JP88 / 00157). Although it is an invention, it can be widely used in hybrid vehicles that use an internal combustion engine and a motor generator together and use the motor generator for auxiliary acceleration and auxiliary braking.
[0003]
[Prior art]
The hybrid vehicle disclosed in the above international publication will be briefly described. This device is shown in FIG. 1 (the hardware configuration is the same for both the conventional device and the embodiment device of the present invention). A motor generator 2 constituted by a cage induction machine having a rotor directly connected to a shaft, a battery 3, and an inverter circuit 4 provided between the battery 3 and the motor generator 2. In the electric mode in which the motor generator 2 operates as an auxiliary acceleration motor for accelerating the vehicle, the inverter circuit 4 sends energy from the battery 3 to the motor generator 2 and the motor generator 2 performs electric braking. In the power generation mode that operates, the battery 3 operates to regenerate the electric energy generated in the motor generator 2. The operation of the inverter circuit 4 is computer controlled by a control program set in the control circuit 5.
[0004]
In the power generation mode, the electric energy generated by the motor generator 2 is consumed by the resistor 11 via the semiconductor switch 12, so that the vehicle can be effectively decelerated by electric braking. The generated electrical energy is dissipated by the resistor 11. In order to make effective use of energy, it is efficient to control the battery 3 to regenerate as much electrical energy generated by this electric braking as possible.
[0005]
The control circuit 5 outputs the rotation sensor 6 that detects the rotation of the internal combustion engine 1 and the motor generator 2 to which the rotation shaft is directly connected, the output of the vehicle speed sensor 16 provided on the vehicle wheel (or transmission), The output of the accelerator sensor 17 that detects the state of the accelerator pedal 21 that is operated by the driver and the output of the brake sensor 18 that detects the state of the brake pedal 22 that is operated by the driver are taken in, and the motor generator is generated according to the operating state. 2 is controlled to the electric mode and the power generation mode.
[0006]
For example, when there is a certain ratio between the rotation detected by the rotation sensor 6 and the rotation detected by the vehicle speed sensor 16, and this matches one gear ratio of the transmission, the transmission is set. In this state, when the brake pedal 22 is released and the accelerator pedal 21 is depressed, the driving operation is commanding acceleration. At this time, the motor generator 2 is controlled to the electric mode, and the motor generator 2 performs auxiliary acceleration of the vehicle by the electric energy supplied from the battery 3.
[0007]
Further, when the accelerator pedal 21 is released while the vehicle speed sensor 16 detects a speed equal to or higher than a predetermined value, a so-called engine brake state is established, and the motor generator 2 is switched to the power generation mode to decelerate the vehicle. And the battery 3 is charged with the electric energy generated thereby. When the accelerator pedal 21 is released and the brake pedal 22 is stepped on, the motor generator 2 enters the power generation mode and assists the deceleration of the vehicle in order to assist the braking action also at this time.
[0008]
This device is an excellent hybrid vehicle. For example, while the vehicle is traveling at a normal traveling speed, the accelerator pedal 21 is displaced from a deeply depressed position to a slightly depressed position, and is maintained at that position for a while. When the motor generator 2 is in such a state, the motor generator 2 may repeatedly enter the electric mode or the electric power generation mode to cause a so-called hunting phenomenon. If the accelerator pedal is kept depressed for a certain period of time, the control circuit 5 determines that the engine brake is in effect. At this time, the vehicle is decelerated, and the motor generator 2 automatically switches to the power generation mode in order to regenerate braking energy generated by the deceleration. Immediately after that, if the driver slightly depresses the accelerator pedal 21, the mode of the motor generator 2 is switched from the power generation mode to the motor mode, and it returns to the power generation mode again. May cause such hunting phenomenon. This appears as an impact or vibration in the longitudinal direction of the vehicle, and passengers such as passengers or passengers feel uncomfortable.
[0009]
In order to solve this, the applicant of the present invention provides a difference between the conversion condition from the electric mode to the power generation mode and the conversion condition from the power generation mode to the electric mode, that is, the conditions for conversion and reverse conversion between the two modes. Patent application for a technique for preventing this hunting phenomenon by providing hysteresis (see Japanese Patent Application No. 7-73713 and Japanese Patent Application Laid-Open No. 8-275305, hereinafter referred to as “prior application invention”).
[0010]
This prior invention will be briefly described by way of example. FIG. 3 is an operation explanatory diagram in which the horizontal axis represents the rotational speed of the motor generator and the vertical axis represents the current of the motor generator. When it is in (+), the motor generator is in the motor mode, and when the current is in the negative region (-), it indicates that the motor generator is in the power generation mode. The operating point is now at point A on this figure, and when the electric mode, that is, auxiliary acceleration is being performed, the position of the accelerator pedal (not shown in this figure) is maintained at a low level constant position. Then, as acceleration is performed and the rotational speed increases, the current supplied to the motor generator decreases and becomes zero. The rotational speed of the motor generator at this time is _R0 . The motor generator automatically switches to the power generation mode because the rotational speed of the motor generator becomes R ₀ and the speed of the accelerator pedal does not change, but the vehicle speed increases. However, the rotational speed instead of converted to immediately power generation mode in this case prior invention, the first time as well as to be converted into power generation mode when further rotational speed has reached the R ₁ rises, the reverse from the power generation mode When it gradually decreases, it is devised to switch to the electric mode at the rotation speed R ₀ .
[0011]
In other words, the rotational speed of the motor generator is set as one of the conditions for switching between the electric mode and the power generation mode, the rotation point is the rotational speed R ₁ from the electric mode to the power generation mode, and the rotational speed from the power generation mode to the electric mode. As R ₀ , hysteresis is provided for this operating characteristic. As a result, the phenomenon in which the mode change occurs alternately can be avoided because the motor generator rotation speeds R ₁ and R ₀ are separated from each other. Therefore, the hunting phenomenon in which the two modes frequently change frequently is avoided. It was possible to avoid it.
[0012]
[Problems to be solved by the invention]
The inventor of the present application repeatedly tested this conventional apparatus. And I tried various driving operations while driving. As shown in FIG. 3, the hysteresis condition (horizontal axis) is not only the rotational speed, but also tests such as giving time (or delay time) were conducted. It has been found that by providing such a hysteresis control means and appropriately adjusting this hysteresis characteristic, it is possible to almost eliminate the hunting phenomenon in which the mode change and the reverse change are mutually repeated. It was also found that the shock or vibration generated in the vehicle with the mode change inside cannot be completely extinguished. In particular, it was found that the shock of “Gakun” remains when the motor generator switches from the electric mode to the power generation mode.
[0013]
The present invention has been made in such a background, and it is an object of the present invention to reduce the impact or vibration generated in the vehicle as the motor generator changes modes while the vehicle is running. In particular, an object of the present invention is to reduce an impact generated when a motor generator is switched from an electric mode to a power generation mode while the vehicle is running. An object of the present invention is to reduce the impact generated when the motor generator changes modes so that the passenger does not feel uncomfortable.
[0014]
[Means for Solving the Problems]
In addition to the hysteresis control means, the present invention provides a delay means for controlling the current generated from the motor generator to the target value at once, instead of controlling it to the target value gradually with the passage of time. Features.
[0015]
That is, the present invention includes an accelerator sensor (17, numerals are reference numerals of the embodiment drawing shown in FIG. 1, the same applies hereinafter), a rotation sensor (6) for detecting the rotation of the motor generator (2), the rotation sensor and And a control circuit (5) for controlling the motor generator according to the output of the accelerator sensor. The control circuit (5) includes a condition for the motor generator (2) to switch from the motor mode to the power generation mode and the power generation mode. In the hybrid vehicle control device including the hysteresis control means that provides a difference between the condition for switching from the motor mode to the electric mode, the control circuit (5) is configured to change the motor generator (2) when switching from the electric mode to the power generation mode. 2 is provided with a delay means (control curve illustrated in FIG. 2) for gradually increasing the current of the current to the control target value over time.
[0016]
With such a configuration, the traveling direction acceleration applied to the vehicle in accordance with the mode change does not change suddenly, and the design can be made such that there is almost no shock or vibration that makes the passenger feel uncomfortable.
[0017]
This is not limited to when switching from the electric mode to the power generation mode, but can be configured to increase the motor generator current gradually to the control target over time even when switching from the power generation mode to the electric mode. .
[0018]
Such control may be configured such that the control circuit (5) is provided with memory means for recording a current change pattern with time, and the current is controlled according to the pattern read from the memory means. it can. More specifically, the current value can be determined by controlling the conduction angle of a semiconductor switch (in FIG. 1, a semiconductor switch in the inverter circuit 4) controlled by the output of the control circuit.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a hardware configuration diagram of an apparatus according to an embodiment of the present invention. In this apparatus, the rotating shaft of the motor generator 2 is directly connected to the crankshaft of the internal combustion engine 1. The motor generator 2 is constituted by a squirrel-cage induction machine, and is driven by supplying a three-phase alternating current that gives a rotating magnetic field having a rotational speed larger than the rotational speed of the rotating shaft to the field winding in the electric mode. In the power generation mode, a three-phase alternating current that supplies a rotating magnetic field having a rotational speed smaller than the rotational speed of the rotating shaft to the field winding of the motor generator 2 is supplied. At this time, the mechanical energy given to the rotating shaft is converted into electric energy, which can be taken out from the field winding as a three-phase alternating current. The alternating current supplied to the motor generator 2 is obtained by converting the direct current supplied from the battery 3 by the inverter circuit 4. The three-phase alternating current generated when the motor generator 2 operates as a generator is converted into a direct current by the inverter circuit 4 and regenerated so as to charge the battery 3. The frequency on the AC side of the inverter circuit 4, that is, the rotational speed of the rotating magnetic field of the motor generator 2 takes in the output of the rotation sensor 6 that detects the rotational speed of the rotating shaft of the internal combustion engine 1, that is, the motor generator 2. It is controlled by a control circuit 5 that controls.
[0020]
That is, when auxiliary acceleration is performed with the motor generator 2 in the electric mode, the control circuit 5 takes in the output of the accelerator sensor 17 linked to the accelerator pedal 21 and is slightly larger than the rotation speed detected by the rotation sensor 6 (positive slip). The inverter circuit 4 is controlled so that a rotating magnetic field (with a rate of 0 to several percent) is generated in the field winding of the motor generator 2. At this time, electric energy is supplied from the battery 3 to the motor generator 2. When auxiliary braking is performed by operating the motor generator 2 in the power generation mode, the control circuit 5 generates a rotating magnetic field slightly smaller than the rotation speed detected by the rotation sensor 6 (with a negative slip ratio of 0 to several percent). The inverter circuit 4 is controlled so as to be generated in the two field windings. At this time, energy is supplied from the motor generator 2 to the battery 3 or is consumed by the resistor 11 via the semiconductor switch circuit 12. At this time, the terminal voltage of the battery 3 is observed by the detection circuit 13. If the battery 3 has a margin for charging, the switch control circuit 14 sets the semiconductor switch circuit 12 in a non-conducting state, and the current charges the battery 3. Flowing. If the battery 3 is already fully charged and there is no room for charging, the switch control circuit 14 brings the semiconductor switch circuit 12 into a conducting state, and the electrical energy generated by braking in the motor generator 2 is dissipated by the resistor 11.
[0021]
The vehicle speed sensor 16 is a sensor that detects wheel rotation or rotation on the transmission output side, and the control circuit 5 is used to know which gear the transmission is currently set to. The standard terminal voltage of the battery 3 is, for example, 300V, which is too high and inconvenient for use in the electric equipment in the vehicle, and is therefore converted into 24V by the DC / DC converter 19 and supplied to the vehicle. The capacitor 7 is for maintaining the voltage at the DC side terminal of the inverter circuit 4 constant regardless of the control of the inverter circuit 4.
[0022]
The configurations and operations of the device, the control circuit 5 and the inverter circuit 4 disclosed in FIG. 1 are already well known and have been described in the above-mentioned International Publication, so detailed description thereof will be omitted here.
[0023]
Here, the feature of the present invention resides in current control when the motor generator 2 performs mode switching. FIG. 2 is an operation explanatory diagram illustrating the current control characteristics of the embodiment device of the present invention. The horizontal axis in FIG. 2 is the rotational speed (rpm) of the motor generator 2. The vertical axis represents the current (A) of the motor generator, the motor mode in which energy is supplied to the motor generator 2 is set to the positive region (+) side, and the power generation mode in which the energy is extracted from the motor generator 2 is negative. It represents on the region (−) side. Since the motor generator 2 itself is a three-phase alternating current, this “current” is easy to understand when considered on the direct current side of the inverter circuit 4.
[0024]
It is assumed that the vehicle is in a running state, the accelerator pedal 21 is lightly depressed, and its operating point is at A. At this time, the motor generator 2 operates in the electric mode and performs auxiliary acceleration. Assuming that the accelerator pedal 21 does not change due to the driving operation even if the vehicle is gradually accelerated, the rotational speed of the motor generator 2 gradually increases, and the current supplied to the motor generator 2 gradually increases accordingly. Get smaller. When the rotational speed reaches R ₀ , the motor generator 2 is substantially in an idling state and is in a state where neither acceleration nor braking is performed.
[0025]
When the vehicle is further accelerated by the internal combustion engine 1 or a downhill on the road surface and reaches the rotational speed R ₁ , the control circuit 5 switches the mode and the motor generator 2 changes from the motor mode to the power generation mode. In the conventional device described above, this current value is controlled so that the current i, which is the control target value, is taken out from the motor generator 2 immediately. Then, control is performed so as to gradually change the current i to the control target value.
[0026]
The control pattern of the delay means can be set in the control computer of the control circuit 5. More specifically, this control pattern can be set in the storage means in advance, and immediately after this mode switching control is performed, this pattern can be read out and the current can be controlled to increase according to the pattern.
[0027]
FIG. 4 shows a control flowchart of the delay means. Explaining this, the control of the delay means is activated by a command to switch the electric mode to the power generation mode. When the output (R) of the rotation sensor 6 is taken and the output R reaches the rotation speed R ₁ set for the hysteresis control, the control pattern stored in advance in the storage circuit is read. In accordance with this control pattern, the current conduction angle applied to the semiconductor switch of the inverter circuit 4 is controlled to gradually increase from a small value to a large value. When the current value reaches the control target, the control of the delay means is finished. If there is a measured value, this current value can be used, but even if there is no measured value, the control pattern is used to identify that the corresponding current value has been reached and to control this delay control to end. can do.
[0028]
In this example, a test was performed using a pattern in which 0% to 100% of the current i of the control target value was linearly changed over 1 second to 10 seconds. As a result, it was confirmed that the impact applied to the vehicle is reduced as the time required for increasing the current is increased. From the test results, it is possible to eliminate almost all of the shocks that passengers feel uncomfortable by changing the control target current i from 0% to 100% linearly over 5 to 10 seconds. I understood.
[0029]
The control pattern of the delay means can be set to be optimal depending on the mass of the vehicle, the performance of the motor generator, and the size of the control target value. In addition, the pattern curve is not necessarily changed linearly as shown by a straight line in FIG. 2, but the pattern curve can be set convexly upward or convexly as shown by a broken line in FIG. These can be arbitrarily selected and designed according to the nature of the vehicle to be applied. In addition, if the delay time of this delay means is lengthened, the generated impact will be reduced, but the mode change will be delayed substantially, the power generation mode will not start up easily, that is, it will appear as an inconvenience that auxiliary braking will not work easily. Become. This is a problem that should be set by design for each type of vehicle.
[0030]
From the test results, it is known that the impact when the motor generator changes from the electric mode to the electric mode is greater than the impact when the electric generator changes from the electric mode to the electric mode. Sometimes, it can be configured to be gently controlled as well. That is, as indicated by a one-dot chain line in FIG. 2, when the motor generator is switched from the power generation mode to the motor mode, the current control can be controlled so as to change gradually over time. By performing such control, it is possible to reduce the impact generated when switching from the power generation mode to the electric mode. FIG. 5 shows a control flowchart of the delay means at this time. Since the contents of this flowchart can be understood in the same manner as the description of FIG. 4, a detailed description is omitted.
[0031]
【The invention's effect】
As described above, according to the present invention, the shock or vibration generated at the time of switching between the electric mode in which the motor generator auxiliary accelerates the vehicle and the power generation mode in which the vehicle is auxiliary braked is prevented from causing the vehicle occupant to feel uncomfortable. It can be effectively reduced.
[Brief description of the drawings]
FIG. 1 is a hardware configuration diagram of an apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram for explaining the operation of the apparatus according to the embodiment of the present invention.
FIG. 3 is a diagram for explaining the operation of a conventional apparatus.
FIG. 4 is a control flowchart of delay means set in the control circuit of the embodiment device of the present invention (when switching from the electric mode to the power generation mode).
FIG. 5 is a control flowchart of delay means set in the control circuit of the embodiment device of the present invention (when switching from the power generation mode to the electric mode).
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Motor generator 3 Battery 4 Inverter circuit 5 Control circuit 6 Rotation sensor 7 Capacitor 11 Resistor 12 Semiconductor switch circuit 13 Detection circuit 14 Switch control circuit 15 Current detector 16 Vehicle speed sensor 17 Acceleration sensor 18 Brake sensor 19 DC / DC converter 21 Accelerator pedal 22 Brake pedal

Claims (2)

An accelerator sensor; a rotation sensor that detects rotation of the motor generator; and a control circuit that controls the motor generator in accordance with the output of the rotation sensor and the accelerator sensor. In a hybrid vehicle control device including a hysteresis control means that provides a difference between a condition for switching from the mode to the power generation mode and a condition for switching from the power generation mode to the electric mode,
The control circuit includes delay means for gradually increasing the current of the motor generator to the control target value over time when switching from the motor mode to the power generation mode ,
The delay unit includes a memory unit that pre-records a control pattern of a current change with time, and a unit that controls the current according to the control pattern read from the memory unit. .   2. The control apparatus for a hybrid vehicle according to claim 1, wherein the control circuit includes delay means for gradually increasing the current of the motor generator to a control target with the passage of time even when switching from the power generation mode to the electric mode.

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