JP3886940B2 - Control device for hybrid vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an output control technique for a hybrid vehicle, and more particularly to a control device that performs output control of a series hybrid vehicle.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, there is known a hybrid vehicle that travels by combining a plurality of power sources and operating the power sources simultaneously or individually depending on the situation. Depending on the power source used and the method of combination, for example, a hybrid vehicle having the following method has been proposed.
[0003]
One is a series hybrid system, in which a battery is charged with electric power generated by turning a generator with an engine or used as running energy. Here, only the motor turns the wheel, and the engine is characterized by not turning the wheel. Thus, in the series hybrid system, the engine is used only to drive the generator. Moreover, since all the driving force of a wheel is supplied from a motor and the flow of motive power is in series, it is called a series system. The engine is used in the most efficient operating region.
[0004]
The other is a parallel hybrid system, in which the engine is mainly used for traveling and is used as a power source for charging a battery in some cases. When starting or accelerating when a load is applied to the engine, the motor operates to assist the driving force. As described above, the parallel hybrid system obtains driving force from both the engine and the motor, and compensates for each disadvantage by using two driving forces properly. Also, since two power sources are involved in driving in parallel, this is called a parallel system.
[0005]
Passenger cars often use the parallel hybrid system, which can reduce the cost of electrical components, and some examples of applying the series hybrid system can be seen because of the high degree of freedom in layout. Normally, a battery is directly attached to the inverter, and the battery voltage becomes the inverter power supply voltage as it is. In addition, even through a converter, the inverter power supply voltage is controlled to be kept substantially constant (see, for example, Patent Documents 1 to 4).
[0006]
[Patent Document 1]
Japanese Patent Laid-Open No. 2001-119808 [Patent Document 2]
JP 2000-213386 A [Patent Document 3]
JP 2000-197207 A [Patent Document 4]
Japanese Patent Laid-Open No. 2000-175306
[Problems to be solved by the invention]
However, the above-described conventional configuration does not take into account the attachment / detachment, expansion, or reduction of the battery, and the system control always requires a specified battery. For battery control or protection and system control The host system needed fine control. For this reason, the load on the system control apparatus is increased and complicated.
[0008]
The present invention has been made in view of such problems, and an object of the present invention is to provide a hybrid vehicle control device that can be controlled with a simple configuration and is relatively inexpensive.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, a generator connected to an engine, a converter for converting and controlling the output from the generator to direct current, and a battery connected via a bidirectional DC / DC converter. In a configuration in which the generator and the battery are driven by a motor as a power source,
The bidirectional DC / DC converter has a function of supplying a specified charging / discharging current to a DC voltage according to a DC voltage level, and the converter adds and subtracts the electric power input / output by the battery from the vehicle required output. The battery output can be controlled simultaneously by controlling the DC voltage level.
[0010]
Further, a plurality of the batteries can be provided by parallel connection via the bidirectional DC / DC converters. The bidirectional DC / DC converter has a function of supplying a specified charging / discharging current to a DC voltage according to a charge amount and a DC voltage level of the battery.
[0011]
Further, a fuel cell is provided in place of the engine and the generator connected thereto, and another converter for controlling the output of the fuel cell is provided in place of the converter. Further, an electric double layer capacitor is provided instead of the battery.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention exemplifies a hybrid vehicle control apparatus using a series hybrid system. However, the present invention is not limited to this. The series hybrid system does not require a drive shaft that transmits the engine output to the wheels, so the degree of freedom in layout of each component is high.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, a generator connected to an engine, a converter for converting and controlling the output from the generator to a direct current, and a battery connected via a bidirectional DC / DC converter. A control device for a hybrid vehicle that is driven by a motor using the generator and the battery as a power source, and controls a power amount from the generator based on a vehicle required output and a power amount of the battery. A control unit configured to set a DC voltage level of the converter based on the vehicle required output, and to control an amount of electric power from the generator so that the DC voltage level of the converter approaches the set DC voltage level. 2 Based on the DC voltage level from the control unit and the converter, the bidirectional DC / DC converter is charged to the battery. A third control unit that controls the amount of electric current, and sets the amount of power from the converter by the first control unit, and performs control operations by the second and third control units using the DC voltage level. By executing independently, the converter controls the power by adding / subtracting the power input / output from / to the vehicle required output, and the battery output can be controlled simultaneously by operating the DC voltage level. It is characterized by that.
[0014]
FIG. 1 is a block diagram showing a schematic configuration of a control apparatus for a hybrid vehicle according to an embodiment of the present invention. In the figure, reference numeral 1 denotes an engine, and reference numeral 2 denotes a generator connected to the engine and driven to rotate. Reference numeral 3 denotes a converter that converts alternating current from the generator into direct current, and is electrically connected to the generator 2. A smoothing capacitor 4 is connected in parallel to terminals a and b which are output terminals of the converter 3, and a battery 5 is also connected in parallel via a bidirectional DC / DC converter 6 for voltage conversion.
[0015]
A plurality of such configurations of the battery 5 and the bidirectional DC / DC converter 6 can be provided by parallel connection. Further, reference numeral 7 denotes an inverter that converts direct current from the converter 3 and the battery 5 into alternating current for the motor, and the c terminal and d terminal as input terminals are connected to the a terminal and b terminal as output terminals of the converter 3 ( Connected in parallel). A motor 8 is electrically connected to the inverter 7. A wheel 9 is rotatably connected to the motor 8.
[0016]
A DC bus voltage Vbus is applied between the terminals a and b which are output terminals of the converter 3. The bidirectional DC / DC converter 6 for the battery 5 has a function of supplying a specified charge / discharge current to the DC voltage according to the DC voltage level. That is, the battery 5 is charged when the DC voltage level is high, and is discharged when the DC voltage level is low.
[0017]
On the other hand, the converter 3 has a function of controlling the output of the generator 2 connected to the engine 1. Specifically, the output of the generator 2 is controlled by adding and subtracting the electric power input and output by the battery 5 from the output required by the vehicle. At this time, the output from the battery 5 can be simultaneously controlled by manipulating the DC voltage level. That is, the converter 3 controls the battery 5 and the motor 8 by controlling the DC bus voltage Vbus.
[0018]
Here, as described above, the bidirectional DC / DC converter 6 determines whether the battery 5 is charged or discharged according to the DC bus voltage. For example, in order to correspond to the output (load) required by the vehicle, when the rotation of the engine 1 increases and the converter 3 outputs, the DC bus voltage increases. At this time, the battery 5 is controlled as charging. Further, when the inverter 7 absorbs electric power, the DC bus voltage decreases, so that the battery 5 is controlled as discharging.
[0019]
Then, the inverter 7 outputs the sum of the power from the battery 5 and the power from the converter 3 to the motor 8. In this way, the battery 5 and the motor 8 can be controlled only by controlling the DC bus voltage. Since control of the battery 5 itself is left to the bidirectional DC / DC converter 6 only, the converter 3 only needs to monitor the command of what output the driver wants to make the vehicle and the DC bus voltage.
[0020]
FIG. 2 is a block diagram schematically showing the battery control system in the present embodiment. As shown in the figure, first, the battery charging / discharging current control block 11 controls (commands) the charging / discharging current of the battery 5 based on the input DC bus voltage Vbus as shown in the graph in the block. FIG. 3 shows the enlarged graph. FIG. 3 is a graph showing an example of the battery charge / discharge current control. In the figure, the horizontal axis represents the DC bus voltage Vbus, and the vertical axis represents the battery current Ib. The battery current Ib is positive on the discharge side and negative on the charge side.
[0021]
For example, when the DC bus voltage Vbus becomes equal to or lower than the discharge start voltage (for example, 620 V), the battery current Ib is discharged and changes linearly. However, it is not limited to changing linearly, and may change, for example, in a curved line. When the DC bus voltage Vbus becomes the maximum discharge current generation voltage (for example, 600 V), the battery current Ib becomes the maximum discharge current Ibmax (for example, 100 A). Even if the DC bus voltage Vbus is equal to or lower than the maximum discharge current generation voltage, the battery current Ib remains at the maximum discharge current for battery protection and does not change.
[0022]
On the other hand, for example, when the DC bus voltage Vbus becomes equal to or higher than the charging start voltage (for example, 670 V), the battery current Ib is in a charged state and changes linearly. However, it is not limited to changing linearly, and may change, for example, in a curved line. When the DC bus voltage Vbus becomes the maximum charging current generation voltage (for example, 700 V), the battery current Ib becomes the maximum charging current -Ibmax (for example, -100 A). Even if the DC bus voltage Vbus is equal to or higher than the maximum charging current generation voltage, the battery current Ib remains at the maximum charging current for battery protection and does not change.
[0023]
Returning to FIG. 2, the battery current command value Ib * from the battery charge / discharge current control block 11 is compared with the actual battery current Ib, and the battery current Ib is controlled in the bidirectional DC / DC current control block 12. .
[0024]
FIG. 4 is a block diagram schematically showing Example 1 of the converter control system in the present embodiment. In the figure, first, a DC bus voltage command value is calculated in a DC bus voltage command value calculation block 13 based on a vehicle request output coming from, for example, a vehicle accelerator, steering wheel, brake, etc., and a DC bus voltage command value Vbus * is obtained. Is output. Subsequently, the command value and the actual DC bus voltage Vbus are compared, and based on this, the DC bus voltage regulator block 14 controls the DC bus voltage.
[0025]
On the other hand, based on the vehicle request output, the FF (feed forward) torque command calculation block 15 calculates the required torque and outputs it. Specifically, the required torque is calculated by the following equation.
(Vehicle required output-battery output) / Generator speed = Requested torque Then, the required torque is output by feedforward, and based on this and the above-mentioned controlled DC bus voltage, the actual DC bus voltage Vbus is monitored. Meanwhile, the converter torque command block 16 outputs the torque command value Tg * of the generator.
[0026]
As described above, the output of the battery can be controlled at the same time by using the DC voltage as the manipulated variable. Since the output control and protection of the battery are shared by the battery side, the vehicle controller can be controlled only by commands to the inverter of the drive motor and the converter of the generator, and the control device is not complicated and relatively inexpensive. In addition, even if a problem occurs in which the battery unit cannot output a predetermined output, the converter increases the generator output and maintains the DC voltage, so that the vehicle operation can be continued. On the other hand, even if a problem occurs in which the generator side cannot output, since the DC voltage fluctuates and the battery side inputs and outputs power, the vehicle operation can be continued.
[0027]
Next, Example 2 of the converter control system in the present embodiment is shown below. Here, the basic configuration is the same as that of FIG. 4 described above, but the configuration is such that a battery connected via a bidirectional DC / DC converter is added or deleted. In other words, as shown by the two-dot chain line in FIG. 1, a plurality (any number) of the batteries 5 are provided by parallel connection via the bidirectional DC / DC converter 6 or deleted.
[0028]
Each bidirectional DC / DC converter 6 monitors the DC bus voltage Vbus in the same manner. And each battery 5 outputs the power which each battery 5 has according to a voltage level. In this case, if data on the number of mounted battery units is input in advance, charge / discharge current control corresponding to the data is performed. In the FF torque command calculation block 15, the required torque is calculated by the following equation.
(Vehicle required output-total output of n batteries) / generator speed = required torque
As a result, the system configuration allows easy addition and deletion of batteries, and even if one of a plurality of battery units is damaged due to troubles during vehicle operation, the operation can be easily continued. Further, even if a problem occurs in which some battery units cannot output a predetermined output, the converter 3 increases the generator output and maintains the DC voltage, so that the vehicle operation can be continued.
[0030]
FIG. 5 is a block diagram schematically showing Example 3 of the converter control system in the present embodiment. In the present embodiment, in addition to the configuration shown in FIG. 4, an SOC (State of Charge), that is, a battery charge amount is input to the DC bus voltage command value calculation block 13. Here, the bidirectional DC / DC converter has a function of supplying a specified charge / discharge current to the DC voltage according to the SOC and the DC bus voltage level. Thereby, overcharge and overdischarge of the battery can be prevented. In addition, it is good also as a structure which monitors the heat from a battery or a bidirectional | two-way DC / DC converter instead of SOC.
[0031]
In addition, in each said Example, it is good also as a structure which has a converter which provides a fuel cell instead of an engine and the generator connected with this, and controls the output. Thereby, it can recombine into an environment-friendly vehicle, without changing control apparatuses other than a converter. Further, an electric double layer capacitor may be used instead of the battery. As a result, it is possible to realize a maintenance-saving system with a long service life by simply changing the battery control unit to the extent of parameter change.
[0032]
In addition, a configuration having two systems, that is, a communication system in which wiring is provided between devices such as an engine, a converter, and an inverter, and an analog or digital discrete system, may be used for operation commands of each configuration. In the discrete system, it does not matter whether there is inter-device wiring. As a result, when the communication system is normal, it operates by communication, but even if a malfunction occurs in the communication system, if the discrete system settings and inputs are given individually, the system can be operated only by operating the inverter that drives the motor. Can be operated, and the reliability of vehicle operation continuity is improved.
[0033]
In addition, each device may have a control device having an output power source that can be used for generating the discrete signal, that is, an output terminal of a control power source. Thereby, when giving a discrete system setting, it is possible to configure by simply connecting an easily available passive component such as a wire to the terminal, and the reliability of vehicle operation continuity is further improved.
[0034]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a control device for a hybrid vehicle that can be controlled with a simple configuration and is relatively inexpensive.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a schematic configuration of a control device for a hybrid vehicle.
FIG. 2 is a block diagram schematically showing a battery control system.
FIG. 3 is a graph showing an example of battery charge / discharge current control.
FIG. 4 is a block diagram schematically showing a first embodiment of a converter control system.
FIG. 5 is a block diagram schematically illustrating a third embodiment of the converter control system.
[Explanation of symbols]
1 Engine 2 Generator 3 Converter 4 Smoothing Capacitor 5 Battery 6 Bidirectional DC / DC Converter 7 Inverter 8 Motor 9 Wheel 11 Battery Charge / Discharge Current Control Block 12 Bidirectional DC / DC Current Control Block 13 DC Bus Voltage Command Value Calculation Block 14 DC bus voltage regulator block 15 FF torque command calculation block 16 converter torque command block

Claims (8)

A generator connected to the engine; a converter for converting and controlling the output from the generator to a direct current; and a battery connected via a bidirectional DC / DC converter; In a hybrid vehicle control device driven by a motor as a source,
A first controller that controls the amount of power from the generator based on a vehicle request output and the amount of power of the battery;
A second control unit that sets a DC voltage level of the converter based on the vehicle required output, and controls the amount of power from the generator so that the DC voltage level of the converter approaches the set DC voltage level;
A third control unit for controlling a charge / discharge current amount that the bidirectional DC / DC converter gives to the battery based on a DC voltage level from the converter;
With
The converter sets the amount of electric power from the converter by the first control unit, and independently executes control operations by the second and third control units using the DC voltage level, so that the converter outputs a vehicle required output. A control apparatus for a hybrid vehicle, which controls power by adding and subtracting power input / output from / to the battery and simultaneously controlling battery output by operating the DC voltage level.   2. The control device for a hybrid vehicle according to claim 1, wherein a plurality of the batteries can be provided by parallel connection via the bidirectional DC / DC converters.   The said bidirectional DC / DC converter has a function which supplies a regular charging / discharging electric current to a DC voltage with the charge amount and DC voltage level of the said battery, The Claim 1 or Claim 2 characterized by the above-mentioned. Control device for hybrid vehicle. The second controller is
  A DC bus voltage command value calculation unit that outputs a DC voltage command value indicating a DC voltage level of the converter set based on the vehicle request output;
  A comparison unit that compares the DC voltage command value from the DC bus voltage command value calculation unit with the DC voltage level from the converter;
  A regulator that brings the DC voltage level from the converter closer to the DC voltage command value based on the output from the comparison unit;
  A torque command calculation unit that sets a torque command value representing torque required for the generator based on the DC voltage level from the converter set by the regulator;
  The hybrid vehicle control device according to claim 1, wherein the control device is a hybrid vehicle control device. The first control unit includes a feedforward torque command calculation unit that sets a torque required for the generator based on a value obtained by subtracting the output of the connected battery from the vehicle request output,
  The torque command calculation unit sets the torque command value by a torque set by the DC voltage level from the converter set by the regulator and a torque set by the feedforward torque command calculation unit. ,
  5. The hybrid vehicle control device according to claim 4, wherein the first control unit includes the feedforward torque command calculation unit and the torque command calculation unit. The third control unit is
  When the DC voltage level is equal to or lower than the discharge start voltage,
  The bidirectional DC / DC converter is controlled so that the discharge current of the battery increases as the DC voltage level decreases, and the DC voltage level is equal to or less than a maximum discharge current generation voltage at which the discharge current of the battery becomes a maximum discharge current. Then, the bidirectional DC / DC converter is controlled so that the discharge current of the battery becomes constant at the maximum discharge current,
  When the DC voltage level is equal to or higher than the charge start voltage higher than the discharge start voltage,
  The bidirectional DC / DC converter is controlled so that the charging current of the battery increases as the DC voltage level increases, and the DC voltage level is equal to or higher than a maximum charging current generation voltage at which the charging current of the battery becomes a maximum charging current. 6. The hybrid vehicle according to claim 1, wherein the bidirectional DC / DC converter is controlled such that a charging current of the battery is constant at the maximum charging current. Control device. Said engine and providing a fuel cell instead of connected the generator to, claims 1 to 6, characterized in that a further converter that controls the output of the fuel cell in place of the converter The control apparatus of the hybrid vehicle in any one of. 8. The hybrid vehicle control device according to claim 1, further comprising an electric double layer capacitor instead of the battery.

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