JP4199331B2 - Vehicle power limiting device with a capacitor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for limiting electric power of a vehicle equipped with a battery (battery) such as an electric vehicle or a hybrid car as a power source.
[0002]
[Prior art]
As is well known, an electric vehicle or a hybrid car travels by supplying electric power from a battery to a motor (electric motor) and rotating wheels by torque output from the motor. On the other hand, at the time of deceleration, the generator is driven by the kinetic energy of the vehicle to generate electric power, and regeneration is stored in the battery. Various types of batteries have been developed, but all types have limited power for discharging and charging, and problems such as shortening the service life if discharged or charged beyond that limit Produce.
[0003]
Therefore, for example, in the device described in Japanese Patent Laid-Open No. 9-294305, an output limit coefficient is obtained from a map based on the current and voltage of the battery, and the output power limit value is obtained by multiplying the coefficient by the maximum output of the battery. ing. Similarly, during regeneration, a regenerative power limit coefficient is obtained from the map based on the battery current and voltage, and the regenerative power limit value is obtained by multiplying the coefficient by the regenerative power maximum value. A driving force command value is determined based on the power limit value, the motor speed, and the target torque.
[0004]
In Japanese Patent Laid-Open No. 9-74605, a charging upper limit power is determined based on the SOC (charge state) and temperature of the battery, and a power constraint value is determined from the charging upper limit power and the power rating of the motor (generator). Further, a regenerative torque upper limit value is determined from the power constraint value and the motor rotational speed.
[0005]
[Problems to be solved by the invention]
By the way, in a conventional general electric vehicle or hybrid car, an inverter is interposed between a battery and a motor or a generator. Therefore, there is a power difference between the power output by the battery and the power generated by the motor, or between the regenerative power input to the generator and the power input to the battery. Inevitably occurs.
[0006]
On the other hand, in any of the devices described in the above-mentioned publications, the motor (generator) torque is determined based on the power limit value and the motor rotation speed, and the loss in the inverter or the motor (generator). Therefore, the charging power is unnecessarily limited at the time of regeneration, and the braking energy recovery rate is reduced. That is, some of the regenerative energy obtained by setting the motor torque obtained as described above is consumed as a loss of the motor or inverter, and the battery is not charged, so the regenerative efficiency is reduced accordingly. To do.
[0007]
In addition, at the time of output, if control is performed so that the motor torque obtained based on the power limit value and the motor rotation speed is obtained, the battery and the electric power corresponding to the motor torque are added to the motor or inverter. Since electric power corresponding to the loss is output, an overdischarge state eventually occurs, which may reduce the useful life of the battery.
[0008]
In addition, energy loss in inverters and motors changes according to the operating state of the motor, etc., so the above-mentioned conventional device has a low regenerative efficiency in the operating region where the loss is large, and an overload condition for the battery during output Could occur.
[0009]
The present invention has been made in view of the above circumstances, and an object thereof is to provide a power limiting device capable of improving regeneration efficiency and preventing overcharge and a decrease in useful life of the battery due to the overcharge. To do.
[0010]
[Means for Solving the Problem and Action]
The present invention, in order to achieve the above object, a driving force for traveling by the electric power output from the capacitor occurs, also by converting the kinetic energy into electric power by the running stored in the capacitor, before Symbol in the discharge or power limiting device for a vehicle for limiting the charging of the capacitor from the capacitor when the power obtained by converting the power or the kinetic energy outputted from the capacitor exceeds a limit value of the capacitor, inverter to the capacitor The electric power including the loss in the inverter and the loss in the motor or the generator mapped based on the rotation speed and the required torque of the motor or the generator connected via the motor, and the rotation speed and the required torque means for calculating the required power in accordance with the losses, the measured value of the rotational speed and power of the motor or generator Based on the map of the torque as a parameter, means for determining the limit torque of the motor or generator be limits on the capacitor at a predetermined of said rotational speed, the required power of the calculated the limit value in the accumulator And means for limiting the torque in the motor or generator to the limit torque when the torque exceeds the limit torque.
[0011]
Therefore, in the device of the present invention, the vehicle is driven by driving the motor with the electric power output from the battery, and the generator is driven by the kinetic energy associated with the running of the vehicle to generate power, and the power is stored in the battery. . In this way, the output from the capacitor, or request power that will be input is determined by the rotational speed and torque as well as the power loss of the motor or generator. Therefore request power that will be input to and output from the storage battery, determined by the rotational speed and the torque and power loss in the motor or generator, required power of that is if exceeds the limit value of the storage battery, the limit value Limited to In order to perform the limitation, the device of the present invention can compensate for at least the energy loss in the motor or generator and the loss in the inverter between the capacitor and the motor or generator based on the limit value and the rotational speed. Find the torque. When driving the motor or generator with the calculated torque, Ruiwayuru actual power output from the electric storage pack, the limit value or less of the value is a value including the loss in the power the motor and the inverter generated by the motor It becomes. Moreover, when inputting into a capacitor | condenser, the electric power which generate | occur | produces with a generator becomes the loss in a generator and an inverter, and the electric power input into a capacitor | condenser, and the electric power input into a capacitor | condenser becomes a limit value. That is, in the device of the present invention, when output from the capacitor, the motor torque is reduced according to at least the number of revolutions and the loss based on the torque in the motor, so that overdischarge is prevented. Since the amount of power generated at the time is increased according to at least the loss in the generator, charging can be performed without excess or deficiency.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Next, the present invention will be specifically described with reference to the drawings. FIG. 2 schematically shows a drive system of an electric vehicle as an example to which the present invention is applied. An output shaft 2 of a motor / generator 1 as a power source is connected via a predetermined transmission mechanism such as a propeller shaft. It is connected to the drive wheel 3. Brakes (not shown) attached to all the wheels including the drive wheels 3 are configured to be electrically controlled based on signals corresponding to brake operations and other control states.
[0013]
The motor / generator 1 is of an AC synchronous type, and a battery (capacitor) 5 is connected to the motor / generator 1 via an inverter 4 for AC / DC conversion and power control. .
[0014]
An electronic control unit (motor ECU) 6 for controlling the motor / generator 1 and the inverter 4 is provided. The motor ECU 6 is mainly composed of a so-called microcomputer, and based on the amount of depression (accelerator opening) of the accelerator pedal (not shown), the vehicle speed, etc., the motor required torque and the state of charge in the battery 5 ( The motor / generator 1 is configured to be controlled according to the generator required torque based on the SOC).
[0015]
An electronic control unit (battery ECU) 7 for controlling the battery 5 is provided. The battery ECU 7 is also composed mainly of a so-called microcomputer, and is configured to monitor the SOC of the battery 5 and output a signal corresponding to the result.
[0016]
As described above, the brake is configured to be electrically controllable, and an electronic control unit (brake ECU) 8 for controlling the brake is provided. The brake ECU 8 is also mainly composed of a microcomputer, and is configured to control the braking torque by the brake by a signal based on a braking operation, a regeneration request signal, or the like.
[0017]
These ECUs 6, 7, and 8 are connected to each other so that data communication is possible. Data relating to the state of charge, current, voltage, and the like are transmitted from the battery ECU 7 to the motor ECU 6, and a regeneration request value, a regeneration execution value, and the like are transmitted and received between the brake ECU 8 and the motor ECU 6.
[0018]
In the electric vehicle having the above-described drive system, when there is an output request due to depression of an accelerator pedal, the motor / generator 1 is controlled so that torque that meets the request is generated. This is executed by the motor ECU 6 performing an operation based on the input signal and controlling the motor / generator 1 and the inverter 4 according to the result. When the brake is operated, regenerative control is executed to convert the kinetic energy of the vehicle into electric energy. That is, while braking is performed by the brake, the motor / generator 1 is driven by torque input from the drive wheel 3 side to generate electric power, and the battery 5 is charged with the electric power via the inverter 4. This control is executed by the brake ECU 8 controlling the braking force by the brake based on the regeneration execution signal from the motor ECU 6 with respect to the regeneration request value of the brake ECU 8.
[0019]
When the output from the battery 5 for driving and the input to the battery 5 by regeneration are performed, the input / output value is limited depending on the state of the battery 5, and thus the power is limited as follows. FIG. 1 shows an example of the control. First, a required torque Tm in the motor / generator 1 is inputted (step 1). The required torque Tm is obtained based on the vehicle speed, the accelerator opening, and the like at that time when the motor / generator 1 generates a driving force for powering. Moreover, in the case of regeneration, it can obtain | require based on a vehicle speed and brake force, for example.
[0020]
Next, the battery power Pb at the required torque Tm is calculated (step 2). That is, Pb = Nm.Tm + Pmlos
Is calculated. Here, Nm is the rotational speed of the motor / generator 1 and Pmlos is the power loss in the motor / generator 1. The power loss Pmlos is determined based on the rotational speed Nm of the motor / generator 1 and the torque Tm at that time. For example, the power loss Pmlos can be obtained as a map value by performing a test in advance. Further, as means for calculating the battery power Pb, means for using a value detected by the battery ECU 7 or the like may be employed. The power loss may include a loss in the inverter 4.
[0021]
It is determined whether or not the battery power Pb thus obtained exceeds the limit value (step 3). This limit value is the discharge upper limit value Pbmax in the case of outputting, and the charge upper limit value Pbmin in the case of regeneration, which can be determined by the temperature of the battery 5, the SOC, and the like. If the battery power Pb obtained in step 2 does not exceed the limit value, the motor / generator 1 is operated with the motor torque input in step 1. That is, electric power is output or regenerated so that the torque is obtained.
[0022]
On the other hand, when the battery power Pb obtained in step 2 exceeds the upper limit values Pbmax and Pbmin, the motor maximum torque Tmlim at the upper limit values Pbmax and Pbmin is obtained (steps 4 and 5). That is, if the battery power Pb exceeds the discharge upper limit value Pbmax (Pb> Pbmax), the motor maximum torque Tmlim at the battery output upper limit is obtained (step 4). Alternatively, if the battery power Pb exceeds the battery input upper limit value Pbmin (Pb <Pbmin), the maximum torque Tmlim at the battery input upper limit is obtained (step 5). These maximum torques Tmlim are torques when the motor power is at the upper limit values Pbmax and Pbmin and the motor generator 1 is at the current rotational speed Nm, and is determined by taking into account the loss in the motor generator 1.
[0023]
Specifically, a two-dimensional map of the motor torque Tm is created for the target drive system using the rotation speed Nm of the motor / generator 1 and the motor power Pm as parameters. An example is shown in FIG. These motor rotation speed Nm, motor power Pm, and motor torque Tm are actually measured values, and are therefore values including losses generated in the motor / generator 1. Further, the loss in the motor / generator 1 becomes a different value if the operating point such as the rotational speed or the torque is different, but in step 4 or step 5, the motor becomes the upper limit values Pbmax and Pbmin at the current rotational speed Nm. Since the torque Tmlim is obtained, the motor loss at the actual operating point is taken into account.
[0024]
Thus, the motor torque Tm is limited to the maximum torque Tmlim obtained in step 4 or step 5 (step 6). Control is performed so that the torque at the output shaft 2 of the motor / generator 1 becomes the torque set in step 6. Specifically, in the case of power running, the electric power is controlled so that the output shaft torque of the motor / generator 1 becomes the torque set in step 6. Therefore, although the electric power output from the battery 5 becomes the discharge upper limit value, some of the electric power is consumed as a loss in the motor / generator 1, so that it is actually supplied to the output shaft 2 of the motor / generator 1. The power that appears is reduced by the loss. In other words, according to the above control, the maximum motor torque is calculated to be smaller by the loss in the motor / generator 1, so that even if the control is executed based on the motor torque set in step 6, the battery 5 It is possible to prevent a discharge from exceeding the upper limit value of the discharge and to prevent a decrease in its useful life.
[0025]
In the case of regeneration, the braking torque of the brake is controlled to set the torque of the output shaft 2 of the motor / generator 1 to the torque determined in step 6. Since the torque is a value including the motor loss, the power exceeding the charging upper limit value of the battery 5 is generated in the calculation on the output shaft, but the electric power actually output from the motor generator 1 is generated. Is reduced by the motor loss and almost matches the upper limit of charging. As a result, regeneration and charging can be performed without falling below the charge upper limit value, and regeneration efficiency is improved.
[0026]
By the way, as is known from the above-described example, the apparatus of the present invention determines the motor torque at the time of output or regeneration in consideration of the loss in the motor or generator, and executes control of the motor or generator. Therefore, the method of taking the loss into control is not limited to the method shown in the above example, and may be described below.
[0027]
That is, since the motor loss is determined by the motor speed Nm and the motor power Pm, the motor loss Pmlos for each motor speed Pmlos and the motor power Pm is measured for the target drive system and prepared as a map. FIG. 4 shows an example of the map. The motor torque Tm in consideration of the motor loss Pmlos thus obtained is
Tm = (Pm + Pmlos) / Nm
It is. Therefore, if the motor power Pm during power running is the battery maximum output power Pbmax, the limited motor torque Tmlim is
Tmlim = (Pbmax−Pmlos) / Nm
If the motor power Pm during regeneration is the battery maximum input power Pbmin, the limited motor torque Tmlim is
Tmlim = (Pbmin−Pmlos) / Nm
Can be obtained as These calculations may be performed in step 4 or step 5 described above.
[0028]
Even when such control is performed, the motor torque (motor power) is limited in anticipation of loss at the actual operating point of the motor / generator 1, so that overdischarge and overcharge can be prevented. .
[0029]
In step 2 in the control described above, the battery power Pb is obtained by adding the motor loss, and the motor torque or the motor power is limited when the value exceeds the upper limit value. Therefore, in this respect, the control is performed in consideration of the motor loss. Therefore, when the battery power Pb exceeds the upper limit value, the control is based on the difference between the battery power Pb and the upper limit value and the motor rotational speed Nm at that time. The excess torque may be calculated, and the calculated excess motor torque may be subtracted from the actual motor torque at that time to be used as the upper limit value of the motor torque. In that case, since the motor loss at the operating point at the obtained motor torque is different from the motor loss considered in step 2, the control accuracy is slightly reduced at this point, and the tendency of overdischarge or overcharge tends to be reduced. It can happen.
[0030]
Now to explain this invention in the relationship with the above embodiment corresponds to means for calculating the power according to the rotation speed and the required torque and power loss Step 2 that put to the invention, also step 4 is the invention The step 6 corresponds to a means for limiting the torque in the present invention.
[0031]
In the above specific examples, the electric vehicle using only the motor / generator as the power source has been described as an example. However, the present invention is not limited to the above example, and the electric vehicle includes the motor and the generator separately. The main targets are vehicles that are capable of powering and regenerating power, such as hybrid vehicles equipped with a motor / generator and an internal combustion engine as a power source, and hybrid vehicles equipped with a motor / generator and an internal combustion engine. It can be applied to a control device. Further, the motor and the generator in the present invention may be a DC type other than the AC type.
[0032]
【The invention's effect】
As described above, according to the device of the present invention, when controlling the torque to limit the electric power input or output to the battery, the energy based on the limit value and the rotational speed and at least the motor or the generator is used. Calculate the torque that can compensate for the loss and loss in the inverter between the battery and the motor or generator, and drive the motor or generator with the calculated torque to generate the power output from the battery in the motor. This is a value including the power to be lost and the loss in the motor and the inverter, and is a value equal to or less than the limit value. Moreover, when inputting into a capacitor | condenser, the electric power which generate | occur | produces with a generator becomes the loss in a generator and the electric power input into a capacitor | condenser, and the electric power input into a capacitor | condenser becomes a limit value. That the device of the present invention, when outputting from the storage battery, as it reduces in accordance with the loss in the least the motor and the inverter torque of the motor, when over-discharge is prevented, also input to the capacitor, the torque of the generator at least Since it increases according to the loss in the generator, it can be charged without excess or deficiency, and as a result, the regeneration efficiency and the useful life of the battery can be improved.
[Brief description of the drawings]
FIG. 1 is a flowchart for explaining an example of control executed by a control device of the present invention.
FIG. 2 is a diagram schematically showing a drive system of an electric vehicle targeted by the present invention.
FIG. 3 is a diagram illustrating an example of a map of motor rotation speed including motor loss, motor power, and motor torque.
FIG. 4 is a diagram showing an example of a motor loss map based on motor rotation speed and motor power.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Motor generator, 4 ... Inverter, 5 ... Battery, 6 ... Motor ECU, 7 ... Battery ECU, 8 ... Brake ECU.

Claims (1)

The driving force for traveling by the electric power output from the capacitor occurs, also the kinetic energy due to running is converted into electric power stored in the capacitor, and converting the power or the kinetic energy output from the previous SL condenser in the discharge or power limiting device for a vehicle for limiting the charging of the capacitor from the capacitor when the power exceeds the limit value of the storage battery;
Based on the rotation speed and required torque of the motor or generator connected to the capacitor via an inverter, and the rotation speed and required torque, the loss in the inverter and the motor or generator It means for calculating the required power according to the power loss including loss,
On the basis of the measured values of rotational speed and power of the motor or generator map of torque as a parameter, means for determining the limit torque of the motor or generator be limits on the capacitor at a predetermined of said rotational speed ,
The vehicle having a storage battery, characterized in that it comprises a means for limiting the torque to the limit torque in the motor or generator when the request power the calculated exceeds the limit value in the accumulator Power limiting device.

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