JP5826907B2 - Electric vehicle power control device - Google Patents

Description

  The present invention relates to a power supply control device for an electric vehicle, and more particularly, to a power source switching control technique for an electric vehicle having a motor (motor) as a drive source and a battery and a capacitor as a power source of the motor.

In recent years, a hybrid electric vehicle (HEV) including an electric motor together with an engine as a driving source of the vehicle, an electric vehicle (EV) using only the electric motor as a driving source, and the like are available. And although the battery is mainly used as the power supply of the said electric motor, a capacitor can also be used.
In general, the power source of the motor is required to have both a large charge capacity and a light weight / small volume, that is, high energy density and charge / discharge characteristics that can cope with various acceleration / deceleration patterns. A battery has good characteristics in terms of energy density, but generates heat during charging and discharging. For this reason, depending on the conditions, there is a need to add a power output limitation by a protection circuit against self-heating, or the battery itself may be deteriorated. Such an influence is caused by, for example, charging / discharging of a large current or continuous repeated charging / discharging. On the other hand, the capacitor is suitable for charge / discharge of a large current and repeated charge / discharge, and has good charge / discharge characteristics. On the other hand, it does not reach the battery in terms of energy density, and as a result, the charge capacity that can be mounted on the electric vehicle is smaller than that of the battery.

  Paying attention to such characteristics, there is a technique in which charging of a capacitor is performed at the time of braking when a large current is generated, and charging to the battery is performed at the time of non-braking to avoid rapid charging (see Patent Document 1).

JP 2010-202189 A

In Patent Document 1, switching between the battery and the capacitor is performed in accordance with the driver's accelerator operation and brake operation, and the capacitor is charged during braking when the accelerator operation is not performed and the brake operation is performed.
However, for example, when traveling on a road where the uphill road and the downhill road are continuous with a short cycle (hereinafter referred to as a continuous uphill road), the accelerator and the regenerative braking on the uphill road and the regenerative braking on the downhill road are performed. Since the brake operation is alternately repeated in a short time, when the above-mentioned Patent Document 1 is applied, the power source is frequently switched between the battery and the capacitor, and there is a possibility that the battery is loaded.

As described above, when the battery and the capacitor are switched as the power source of the electric motor according to the operation state of the driver, a load is applied to the battery or the power consumption efficiency is deteriorated depending on the driving condition of the vehicle. There is a risk of
The present invention has been made to solve such a problem. The object of the present invention is to select an appropriate power source according to the running state of the vehicle and to efficiently use the power source of the motor. An object of the present invention is to provide a power supply control device for an electric vehicle that can prevent deterioration of the power supply.

To achieve the above object, the power control device for an electric vehicle according to claim 1, the first power supply and short-term than the first power supply as a power source for power generation motor capable by the drive and regenerative vehicle An electric vehicle power supply control apparatus including a second power source that efficiently charges and discharges a large current, wherein a climbing slope and a descending slope with a predetermined slope or more within a predetermined section on the course of the vehicle have a predetermined frequency or more. Continuous uphill / downhill road judging means for predicting repeated uphill / downhill slopes and judging the entry of the vehicle into the continuous uphill / downhill road, and power source selecting means for selecting the first power source or the second power source as the power source of the motor. When the continuous climbing slope determining means determines that the host vehicle has entered the continuous climbing slope, the power of the motor is switched to the second power by the power selection means, and the second power of Using source is characterized by comprising, a power supply switching control means for charging from the power supply and the motor to the motor.

  According to a second aspect of the present invention, there is provided a power supply control device for an electric vehicle according to the first aspect, further comprising a charge state detection means for detecting a charge state of the second power supply, wherein the power supply switching control means is controlled by the continuous climbing slope determination means. When it is determined that the host vehicle has entered the continuous climbing slope, and the charging state of the second power source detected by the charging state detecting unit is outside a predetermined range, the power source selecting unit The power source of the electric motor is switched to the first power source.

  According to the power control apparatus for an electric vehicle according to claim 1 of the present invention using the above means, in an electric vehicle provided with a first power source and a second power source as a power source of an electric motor for driving the vehicle, the vehicle continuously climbs. When entering the slope, the power source of the motor is switched to the second power source by the power source selection means. Therefore, during continuous climbing slope traveling, power supply (discharge) to the motor and charging from the motor are preferentially performed using the second power source.

  During continuous climbing and descending slope roads, high-torque operation and regenerative braking are repeated, so the power source of the motor repeats charging and discharging of a high current in a short cycle, but the power source is shorter than that of the first power source. By selecting a second power source that can efficiently charge and discharge a large current, it is possible to efficiently consume and recover power. In addition, by not using the first power source during continuous climbing slope traveling, it is possible to prevent the first power source from being deteriorated due to repeated charge and discharge.

In addition, by selecting the power source to be used preferentially from the driving environment of the vehicle whether or not the vehicle has entered the continuous climbing slope regardless of the driver's operation state, the selection of the power source suitable for the driving state of the vehicle It can be performed.
According to the power control apparatus for an electric vehicle according to claim 2, when the state of charge of the second power source is out of a predetermined range during traveling on a continuous uphill / downhill road, the second power source is disconnected as the power source of the motor. Therefore, the second power source is switched to the first power source by the power source selection means.

  As a result, overcharging and insufficient charging of the second power source can be prevented, and the performance of the second power source can be maintained.

BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic block diagram which showed the whole structure in one Embodiment of the power supply control apparatus of the electric vehicle which concerns on this invention. It is a flowchart showing a part of control routine which vehicle ECU in one Embodiment of the power supply control apparatus of the electric vehicle which concerns on this invention performs. 3 is a flowchart showing a control routine following FIG. 2.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Referring to FIG. 1, there is shown a schematic configuration diagram of a power supply control device for an electric vehicle according to an embodiment of the present invention.
A vehicle 1 shown in FIG. 1 is a parallel hybrid electric vehicle, and an input shaft of a clutch 4 is connected to an output shaft of a diesel engine (hereinafter referred to as an engine) 2. An input shaft of the transmission 8 is connected via a rotating shaft of an electric motor 6 that can generate electric power, such as a synchronous motor. The output shaft of the transmission 8 is connected to the left and right drive wheels 16 via a propeller shaft 10, a differential device 12 and a drive shaft 14.

The engine 2 is a prime mover that is generally used for automobiles, and may be a gasoline engine other than a diesel engine.
In the vehicle 1 having the configuration, when the clutch 4 is connected, both the output shaft of the engine 2 and the rotating shaft of the electric motor 6 are mechanically connected to the drive wheels 16 via the transmission 8, and the clutch 4 is disconnected. When this is done, only the rotating shaft of the electric motor 6 is mechanically connected to the drive wheels 16 via the transmission 8.

The vehicle 1 is also equipped with a battery 18 (first power source) and a capacitor 20 (second power source) as power sources for the electric motor 6. The battery 18 is a secondary battery such as lithium ion or nickel metal hydride, and the capacitor 20 is an electric double layer capacitor.
The battery 18 and the capacitor 20 are electrically connected to a power source selection unit 22 (power source selection means), and the power source selection unit is electrically connected to the electric motor 6 via an inverter 24.

The power source selection unit 22 can select one of the battery 18 and the capacitor 20 as the power source of the electric motor 6. Then, the DC power from the battery 18 or the capacitor 20 selected as the power source is converted into AC power by the inverter 24 and supplied to the electric motor 6.
The electric motor 6 operates as a motor when electric power is supplied, and the driving force is changed to an appropriate speed by the transmission 8 and then transmitted to the driving wheels 16. Further, when the vehicle decelerates, the electric motor 6 functions as a generator, and the electric motor 6 generates AC power by the driving force transmitted in reverse from the driving wheels 16 and is driven by the regenerative torque generated by the electric motor 6 at this time. A deceleration resistance is applied to the wheel 16. Then, this AC power is converted into DC power by the inverter 24, and then charged to the battery 18 or the capacitor 20 selected as the power source in the power source selection unit 22, and the kinetic energy due to the rotation of the drive wheels 16 is recovered as electric energy. The

  On the other hand, the driving force of the engine 2 is transmitted to the transmission 8 via the rotating shaft of the electric motor 6 when the clutch 4 is connected, and is transmitted to the drive wheels 16 after being shifted to an appropriate speed. Therefore, when the electric motor 6 operates as a motor when the driving force of the engine 2 is transmitted to the driving wheels 16, the driving force of the engine 2 and the driving force of the electric motor 6 are respectively driven via the transmission 8. It will be transmitted to the wheel 16. That is, a part of the driving force to be transmitted to the driving wheels 16 for driving the vehicle 1 is supplied from the engine 2 and the shortage is supplied from the electric motor 6 and assisted.

  Further, when the state of charge (SOC) of the battery 18 or the capacitor 20 decreases and the battery 18 or the capacitor 20 needs to be charged, the electric motor 6 is used as a generator even when the vehicle 1 is traveling. The electric power is generated by operating the electric motor 6 using a part of the driving force of the engine 2 and the AC power generated is converted into DC power by the inverter 24 and then selected by the power source selection unit 22. It is possible to charge the battery 18 or the capacitor 20.

The battery 18 and the capacitor 20 are provided with a corresponding battery ECU 26 and capacitor ECU 28, respectively.
The battery ECU 26 detects the temperature of the battery 18, the voltage of the battery 18, the current flowing between the inverter 24 and the like, and calculates the charging rate of the battery 18.
Capacitor ECU 28 detects the voltage of capacitor 20, the current flowing between inverter 24 and the like, and calculates the charging rate of capacitor 20.

Further, the vehicle 1 is provided with a vehicle ECU 30, and the vehicle ECU 30 of the vehicle 1 receives information from the battery ECU 26 and the capacitor ECU 28 and other information from various sensors and devices (not shown). The vehicle ECU 30 controls various devices based on the input information.
For example, the vehicle ECU 30 has a function of distributing the driving force necessary for driving the vehicle to the engine 2 and the electric motor 6 according to conditions, and controlling each driving force.
The vehicle ECU 30 is connected to a navigation unit 32 (continuous ascending / descending slope judging means), and performs power source switching control and the like in the power source selection unit 22 based on information from the navigation unit 32.

  The navigation unit 32 is connected to an information receiving unit 34 that receives information from the outside. The information receiving unit 34 receives, for example, a GPS (Global Positioning System) signal from an artificial satellite and receives current position information of the own vehicle 1, or a roadside beacon or FM multiplexing using VICS (registered trademark). It consists of a road traffic information receiver that receives traffic information such as the presence / absence, occurrence location, and scale of traffic on the route of the vehicle from the broadcast.

The navigation unit 32 stores map information in advance, and the map information includes information such as road position and width, road gradient, and altitude. Then, the navigation unit 32 compares the information received by the information receiving unit 34 to calculate the positional relationship between the vehicle and the road.
Further, the navigation unit 32 detects an uphill road and a downhill road having a predetermined gradient or more in a predetermined section on the course of the host vehicle, and calculates the frequency of the uphill road and the downhill road in the predetermined section. Then, a predetermined continuous uphill road where the uphill road and the downhill road with a predetermined gradient or more repeat within a predetermined section at a predetermined frequency or more is determined.

The vehicle ECU 30 performs power source switching control for switching to the battery 18 or the capacitor 20 as the power source for the electric motor 6 based on road information obtained from the navigation unit 32.
Hereinafter, the power supply switching control executed in the vehicle ECU 30 will be described in detail.

FIGS. 2 and 3 show flowcharts showing a power supply switching control routine executed in the vehicle ECU, which will be described below.
As shown in step S <b> 1 of FIG. 2, the vehicle ECU 30 first acquires road information from the navigation unit 32.
In the subsequent step S2, it is determined whether or not the own vehicle has entered the predetermined continuous ascending / descending slope described above from the acquired road information. If there is no continuous climbing slope on the course of the own vehicle, or if the own vehicle has not entered the continuous climbing slope even if there is a continuous climbing slope, the determination result is false (No), and the process proceeds to step S3. .

  In step S <b> 3, the vehicle ECU 30 normally controls the power supply selection unit 22. The normal control is to control the power source selection unit 22 so that the battery 18 is mainly used as the power source of the electric motor 6. Specifically, during normal control, the vehicle ECU 30 selects the battery 18 as the power source of the electric motor 6 by the power source selection unit 22 when the charging rate of the battery 18 is within a predetermined range, and the charging rate of the battery 18 is out of the predetermined range. If so, control is performed to select the capacitor 20.

On the other hand, in the above step S2, if the own vehicle has entered a continuous climbing slope, the determination result is true (Yes), and the process proceeds to step S4.
In step S4, the vehicle 1 is decelerating, for example, traveling on a downhill road, and it is determined whether or not the electric motor 6 functions as a generator and the power source is charged by regeneration. If the determination result is true (Yes), the process proceeds to step S5.

  In step S5, based on the information obtained from the capacitor ECU 28, it is determined whether or not the capacitor charging rate is smaller than a predetermined upper limit value (for example, 100%) of the capacitor charging rate. When the capacitor charging rate is smaller than the upper limit value and the capacitor 20 can be charged, the determination result is true (Yes), and the process proceeds to step S6.

In step S6, the vehicle ECU 30 selects the capacitor 20 as a power source by the power source selection unit 22 in order to charge the capacitor 20 with the energy obtained by the regeneration, and returns the routine.
On the other hand, if the capacitor charging rate has reached the upper limit value in step S5, the determination result is false (No), and the process proceeds to step S7.

  In step S7, based on the information obtained from the battery ECU 26, it is determined whether or not the battery charging rate is smaller than a predetermined upper limit value (for example, 80%) of the battery charging rate. When the battery charge rate is smaller than the upper limit value and the battery 18 can be charged, the determination result is true (Yes), and the process proceeds to step S8.

  In step S8, it is determined based on information obtained from the battery ECU 26 whether or not the battery state is good. This is based on the temperature of the battery 18, for example, and if the temperature of the battery 18 is lower than a predetermined temperature at which the deterioration of the battery 18 becomes severe, it is determined that the battery state is good, and the determination result is true (Yes). Proceed to S9.

In step S9, the vehicle ECU 30 selects the battery 18 as a power source by the power source selection unit 22 in order to charge the battery 18 with the energy obtained by the regeneration, and returns the routine.
On the other hand, if the determination result in step S7 or step S8 is false (No), that is, if the battery charge rate is equal to or higher than the upper limit value, or the battery temperature is equal to or higher than a predetermined temperature, the battery condition is not good. The process proceeds to step S10.

In step S10, the vehicle ECU 30 stops the request for the regenerative driving force with respect to the electric motor 6, or stops the charging of the battery 18 and the capacitor 20 with the energy obtained by the regeneration by setting the power source selection unit 22 to the neutral state. Return routine.
In this way, during charging while traveling on a continuous uphill / downhill road, the capacitor 20 is preferentially charged until the capacitor charging rate reaches the upper limit value. After the capacitor charging rate reaches the upper limit value, when the battery 18 can be charged, the power source is switched to the battery 18, and when the battery 18 is in an unchargeable state, the charging is stopped.

On the other hand, in the above step S4, when it is not during charging, that is, when the vehicle 1 is traveling on an uphill road or the like, mainly when power is supplied from the power source to the motor 6, the determination result is false (No). The process proceeds to step S11 in FIG.
In step S11, based on the information obtained from the capacitor ECU 28, it is determined whether or not the capacitor charging rate is larger than a predetermined lower limit value (for example, 10%) of the capacitor charging rate. When the capacitor charging rate is larger than the lower limit value and the capacitor 20 can be discharged, the determination result is true (Yes), and the process proceeds to step S12.

In step S12, the vehicle ECU 30 controls the power source selection unit 22 to select the capacitor 20 as a power source in order to drive the electric motor 6 by discharging (power supply) from the capacitor 20, and the routine returns.
On the other hand, if the capacitor charging rate has reached the lower limit in step S11, the determination result is false (No), and the process proceeds to step S13.

  In step S13, based on the information obtained from the battery ECU 26, it is determined whether or not the battery charging rate is larger than a predetermined lower limit value (for example, 20%) of the battery charging rate. When the battery charging rate is greater than the lower limit value and the battery 18 can be discharged, the determination result is true (Yes), and the process proceeds to step S14.

In step S14, as in step S8, it is determined based on information obtained from the battery ECU 26 whether or not the battery state is good. If the determination result is true (Yes), the process proceeds to step S15.
In step S15, the vehicle ECU 30 controls the power source selection unit 22 to select the battery 18 as a power source in order to drive the electric motor 6 by discharging (power supply) from the battery 18, and the routine returns.

On the other hand, when the determination result is false (No) in step S13 or step S14, that is, when the battery charge rate is equal to or lower than the lower limit value, or the battery temperature is equal to or higher than a predetermined temperature, and the battery state is not good. The process proceeds to step S16.
In step S16, the vehicle ECU 30 switches the driving of the vehicle from the driving of the electric motor 6 to the driving by the engine 2 by stopping the distribution of the driving force to the electric motor 6 in order to stop the discharge in the battery 18 and the capacitor 20. Return routine.

  In this way, during discharging during continuous climbing slope traveling, the capacitor 20 is preferentially discharged until the capacitor charging rate reaches the lower limit value. After the capacitor charging rate reaches the lower limit value, when the battery 18 can be discharged, the power source is switched to the battery 18, and when the battery 18 is in a non-dischargeable state, the discharge is stopped and only the engine 2 is used. The vehicle 1 is driven.

By repeating the control routine as described above, the vehicle ECU 30 preferentially discharges (electric power supply) the electric motor 6 and charges from the electric motor 6 using the capacitor 20 during traveling on a continuous uphill / downhill road.
Thus, even during running on a continuous uphill road where the high-torque operation on the uphill road and the regenerative braking on the downhill road are repeated and the power source of the electric motor 6 repeatedly charges and discharges a large current in a short cycle, the power supply is shorter than that of the battery 18. By selecting the capacitor 20 that can efficiently charge and discharge in between, power consumption and recovery can be performed efficiently. In addition, since the battery 18 is not used as much as possible during continuous climbing slopes, deterioration of the battery 18 due to repeated charge and discharge can be prevented.

Moreover, the power supply suitable for the driving | running state of the vehicle 1 is selected by selecting the power supply used preferentially from the driving | running | working environment of the vehicle whether the vehicle 1 entered the continuous ascending / descending slope regardless of a driver | operator's operation state. Can be selected.
When the charging rate of the capacitor 20 falls outside the predetermined range from the upper limit value to the lower limit value while traveling on a continuous uphill / downhill road, the power source selection unit 22 removes the capacitor 20 from the capacitor 20 as a power source for the motor 6. Switch to battery 18. As a result, overcharging and insufficient charging of the capacitor 20 can be prevented and the performance of the capacitor 20 can be maintained.

From these facts, the power control device for an electric vehicle according to the present invention can select an appropriate power source according to the running state of the vehicle 1 and can efficiently use the power source of the electric motor 6 and can also prevent the battery 18 from deteriorating. Can be prevented.
Although the description of the embodiment of the power control device for an electric vehicle according to the present invention is finished above, the embodiment is not limited to the above embodiment.

For example, in the above embodiment, the vehicle 1 is a hybrid vehicle including the engine 2 and the electric motor 6 as drive sources, but the present invention is also applicable to an electric vehicle using only the electric motor as a drive source.
Further, in the above embodiment, when the capacitor charging rate is out of the predetermined range (steps S5 and S11), the power source is switched to the battery 18. If the determination result in step S5 or S11 is false (No) so that the battery is not used, the power supply selection unit 22 may be set in a neutral state to stop charging / discharging of the power supply.

DESCRIPTION OF SYMBOLS 1 Vehicle 2 Engine 6 Electric motor 18 Battery (1st power supply)
20 Capacitor (second power supply)
22 Power source selection unit (power source selection means)
26 Battery ECU
28 Capacitor ECU
30 vehicle ECU (power supply switching control means)
32 Navigation unit (continuous climbing slope judging means)
34 Information receiving unit

Claims (2)

The as a power supply for power generation motor capable by the drive and regenerative vehicle 1 power, and the first power source for an electric vehicle equipped with a second power supply to perform charging and discharging efficiently a large current in a short period of time than the power supply A control device,
Continuous climbing slope judgment means for predicting a continuous climbing slope that repeats climbing slopes and descending slopes with a predetermined gradient or more within a predetermined section on the course of the vehicle more than a predetermined frequency, and judging the entry of the vehicle into the continuous climbing slope When,
Power source selection means for selecting the first power source or the second power source as a power source of the electric motor;
When it is determined by the continuous climbing slope determining means that the host vehicle has entered the continuous climbing slope, the power source of the electric motor is switched to the second power source by the power source selecting means , Power supply switching control means for supplying power to the motor using a power source and charging from the motor ;
An electric vehicle power supply control device comprising: Charging state detecting means for detecting a charging state of the second power source;
The power supply switching control means determines that the own vehicle has entered the continuous climbing slope road by the continuous climbing slope judgment means, and the charging state of the second power source detected by the charging state detection means is a predetermined value. 2. The power control apparatus for an electric vehicle according to claim 1, wherein when the power is out of the range, the power source selection means switches the power source of the electric motor to the first power source.

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