JP2018012355A - Hybrid vehicle battery control system - Google Patents

Abstract

In a battery control system for a hybrid vehicle, the performance of evacuation traveling is ensured when required discharge power is increased due to a request from a user during evacuation traveling. A battery control system includes a control device that controls discharge power to a battery. When an abnormality occurs in the engine or the charging system, the control device prohibits driving of the engine and charging of the battery, sets the battery discharge allowable power to the set value for evacuation travel, and drives the electric motor to travel The travel is permitted only in the retreat travel S10. In the retreat travel, when it is determined that the required discharge power to the battery has increased from the operation amount of the acceleration instruction unit and the vehicle speed S16, the retreat travel set value is set to the retreat travel. S17 is sometimes made higher than when it is not determined that the required discharge power has increased. [Selection] Figure 3

Description

  The present invention relates to a battery control system for a hybrid vehicle that includes an electric motor and a generator connected to a battery and an engine, and travels using one or both of the electric motor and the engine as a drive source.

  Conventionally, a hybrid vehicle that includes an electric motor and an engine and travels using one or both of the electric motor and the engine as a drive source is known. A hybrid vehicle is equipped with a battery, which is a power storage unit, for supplying electric power to the electric motor. In a hybrid vehicle, an EV traveling mode in which driving of the engine is prohibited and the vehicle is driven by driving of a motor generator may be set. Moreover, the hybrid vehicle includes a charging system, and the charging system may transmit the driving force of the engine to the generator, and the battery may be charged by supplying the power generated by the generator to the battery.

  Patent Document 1 describes a configuration in which a hybrid vehicle performs a retreat travel that travels using only a motor generator when the engine is abnormal. In this configuration, the outputable power that is the discharge allowable power of the battery is increased during EV traveling, but the increase amount of the outputable power that is the discharge allowable power is suppressed during retreat travel more than when the retreat travel is not performed.

JP 2014-94670 A

  In the configuration described in Patent Document 1, when the engine is abnormal, the engine is stopped, and the retreat travel that travels only by the motor generator with the discharge allowable power suppressed is executed. On the other hand, in a hybrid vehicle, when there is no problem in discharging from the battery when the engine or the charging system is abnormal, the driving of the engine and the charging of the battery are prohibited, and the vehicle is driven while suppressing the discharge allowable power. A configuration in which traveling is permitted only by evacuation traveling is also conceivable. In any of these configurations, the travelable distance during retreat travel can be increased.

  However, when retreating while suppressing the allowable discharge power, depending on the driving situation such as climbing on a hill, merging from outside the main road to the main road at a high vehicle speed, the discharge allowable power is insufficient, and the user There is a possibility that the required performance of evacuation traveling cannot be secured.

  An object of the present invention is to ensure the performance of retreat travel in a battery control system of a hybrid vehicle when required discharge power is increased due to a request from a user during retreat travel.

  A battery control system for a hybrid vehicle according to the present invention includes an electric motor and a generator connected to a battery, and an engine, and battery control for a hybrid vehicle that travels using one or both of the electric motor and the engine as a drive source. A control device that controls discharge power to the battery, and charging that transmits the driving force of the engine to a generator and charges the battery by supplying the power generated by the generator to the battery. System. When an abnormality occurs in the engine or the charging system, the control device prohibits driving of the engine and charging of the battery, sets discharge allowable power of the battery to a set value for retreat travel, and The retreat travel is permitted only by retreat travel that drives by driving the electric motor, and during retreat travel, when it is determined that the required discharge power to the battery has increased from the operation amount of the acceleration instruction unit and the vehicle speed, the retreat travel The set value for use is made higher than when it is not determined that the required discharge power has increased during evacuation travel.

  According to the battery control system for a hybrid vehicle according to the present invention, when the required discharge power is increased due to a request from the user during retreat travel, the discharge permissible power can be increased to ensure retreat travel performance.

1 is a diagram illustrating a basic configuration and a circuit of a battery control system and a hybrid vehicle according to an embodiment of the present invention. In embodiment, it is a figure which shows the method of setting discharge allowable electric power Wout from a map according to battery temperature and SOC which is a charge capacity ratio. It is a figure which shows the flowchart for demonstrating the method to set discharge allowable electric power Wout when it transfers to evacuation driving | running | working at the time of EV driving | running in embodiment. In an embodiment, it is a figure showing an example in which a set value of discharge permissible electric power Wout changes according to a run state at the time of evacuation run conditions with a constant battery temperature in relation to a change in SOC.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following, a case where a motor generator having both functions of an electric motor and an electric generator is used as the electric generator and the electric motor will be described. However, the electric generator may not have an electric motor function. In addition, the electric motor may have no generator function. In addition, the numerical values and the number described below are examples for explanation, and can be appropriately changed according to the specifications of the battery control system of the hybrid vehicle. In the following, when a plurality of embodiments and modified examples are included, they can be implemented by appropriately combining them. In the following description, identical elements are denoted by the same reference symbols in all drawings. In the description in the text, the symbols described before are used as necessary.

  FIG. 1 is a diagram illustrating a basic configuration and a circuit of a battery control system 12 and a hybrid vehicle 10 according to the embodiment. A one-dot chain line in FIG. 1 represents a signal line.

  The hybrid vehicle 10 on which the battery control system 12 is mounted will be described. The hybrid vehicle 10 travels using one or both of the second motor generator 18 and the engine 50 as a drive source. Specifically, the hybrid vehicle 10 includes a battery control system 12, an engine 50, and wheels 52. The battery control system 12 includes a charging system 14, a second motor generator 18 that is an electric motor for driving wheels, and a control device 22. The charging system 14 includes a battery 15, a first motor generator 16 that is a generator, and a power distribution mechanism 17. In the charging system 14, the battery 15 and the first motor generator 16 are connected via a system main relay 23, a step-up / step-down DC / DC converter 24, and an inverter 25.

  The battery 15 includes a battery module that includes a plurality of battery cells that are secondary batteries such as a nickel metal hydride battery or a lithium ion battery, and is configured by electrically connecting the plurality of battery cells in series or in parallel. The battery 15 may be a battery pack configured by electrically connecting a plurality of battery modules in series. The first motor generator 16 and the second motor generator 18 are connected to the battery 15. The DC voltage output from the battery 15 is boosted by the step-up / step-down DC / DC converter 24. The boosted DC power is converted into three-phase AC power by the inverter 25. The converted AC power is supplied to at least one of the first motor generator 16 and the second motor generator 18. Hereinafter, the first motor generator 16 is referred to as a first MG 16, and the second motor generator 18 is referred to as a second MG 18. In FIG. 1, the first MG 16 and the second MG 18 are denoted as MG1 and MG2, respectively.

  Here, each of the first MG 16 and the second MG 18 has both functions of an electric motor and a generator. The first MG 16 is driven by electric power from the battery 15 and also has a function as a starter motor that starts the engine 50. The second MG 18 is driven by being supplied with electric power from the battery 15 and used to drive the vehicle. Specifically, the driving force of the second MG 18 is transmitted to the wheel 52 via the power distribution mechanism 17 and the wheel 52 is driven. The second MG 18 is also used as a generator that charges the battery 15 by regenerative power generation during braking of the vehicle and supplying power to the battery 15.

  The engine 50 is connected to the power distribution mechanism 17 and can drive the wheels 52 by the driving force of the engine 50. Further, the driving force of the engine 50 is transmitted to the first MG 16 via the power distribution mechanism 17, whereby the first MG 16 is driven to generate power. The generated power is converted from alternating current to direct current by the inverter 25 and then stepped down by the step-up / step-down DC / DC converter 24. Then, the reduced power is supplied to the battery 15 and the battery 15 is charged. Thereby, charging system 14 transmits the driving force of engine 50 to first MG 16 and supplies the battery 15 with the power generated by first MG 16 to charge the battery.

  Further, in the hybrid vehicle 10, an EV travel mode and an HV travel mode are set, and the control device 22 described later switches so as to select either the EV travel mode or the HV travel mode according to a user request or a vehicle situation. The hybrid vehicle travels in the selected travel mode. The user request is generated by a user operation using an operation unit such as a switch or a button. The vehicle status is a state of charge (SOC) that is a charge capacity ratio with respect to a full charge capacity of the battery 15, a vehicle required driving force based on an accelerator operation, or the like.

  In the EV travel mode, the driving of the engine 50 is stopped and the vehicle is traveled by the power of the second MG 18. The HV travel mode is a mode in which the engine 50 is allowed to drive and travels by appropriately driving the engine 50 according to the travel state (SOC, output request, etc.). That is, at least one of the engine 50 and the second MG 18 is driven to travel, and power is generated when the SOC decreases. Further, depending on the traveling situation, the vehicle travels only with the driving force of the engine 50. The HV traveling mode can be a mode for traveling so as to maintain the SOC within a predetermined range. At this time, the first MG 16 generates electric power by driving the engine 50 when the SOC falls below the lower limit of the predetermined range, and the driving of the engine 50 is stopped when the SOC exceeds the upper limit of the predetermined range in consideration of hysteresis. The vehicle is driven only by the power of 2MG18.

  The driving force of second MG 18 and engine 50 is transmitted to wheel 52 via power distribution mechanism 17, and hybrid vehicle 10 travels using one or both of second MG 18 and engine 50 as a driving source. The term “during HV traveling” described later may be used in the HV traveling mode, or may be limited to when both the electric motor and the engine are driven in the HV traveling mode. The term “during EV travel” described later may include a state in which the engine is not driven in the HV travel mode.

  The control device 22 is configured by a computer, for example, and includes a CPU that is a calculation unit and a storage unit such as a memory and a hard disk device. The control device 22 controls various devices in the vehicle. For example, the control device 22 controls the on / off operation of switching elements (not shown) of the step-up / step-down DC / DC converter 24 and the inverter 25 to control the rotation speed or torque of the first MG 16 and the second MG 18. The control device 22 controls the on / off operation of the switching element of the step-up / step-down DC / DC converter 24 to control the step-up / step-down operation.

  Moreover, the control apparatus 22 receives the signal showing a detected value from the various sensors mounted in the vehicle. Specifically, the battery control system 12 includes an accelerator opening sensor 30, a vehicle speed sensor 31, a current sensor 32, a voltage sensor 33, and a temperature sensor 34. The accelerator opening sensor 30 is a ratio (%) of an operation amount with respect to an operation amount when an accelerator pedal (not shown) as an acceleration instruction portion is completely operated, that is, when the accelerator pedal is completely depressed. Is detected as the accelerator opening. Note that the acceleration instruction unit is not limited to the accelerator pedal, and may be an accelerator lever or the like that is manually operated by the driver. The vehicle speed sensor 31 detects the vehicle speed of the vehicle.

  The current sensor 32 detects the input / output current of the battery 15. The voltage sensor 33 detects the voltage of the battery 15. The temperature sensor 34 detects the temperature of the battery 15. The accelerator opening sensor 30, the vehicle speed sensor 31, the current sensor 32, the voltage sensor 33, and the temperature sensor 34 each transmit a signal representing a detection value to the control device 22.

  Control device 22 calculates the SOC by integrating the current value of battery 15 detected by current sensor 32. The SOC can also be calculated from the battery voltage value detected by the voltage sensor 33.

  When the start switch (not shown) is turned on by the user, the control device 22 connects the battery 15 and the inverter 25 by switching the system main relay 23 from off to on. As a result, the battery control system 12 is activated. On the other hand, the control device 22 disconnects the connection between the battery 15 and the inverter 25 when the start switch is turned off by the user and the system main relay 23 is switched from on to off. Thereby, the battery control system 12 will be in a halt condition.

  Further, the control device 22 detects when an abnormality occurs in the engine 50 or the charging system 14, and prohibits normal EV traveling and HV traveling when there is no problem in discharging from the battery. The vehicle is allowed to travel only by evacuation. “Retreat travel” prohibits driving of the engine 50 and charging of the battery 15 and drives the second MG 18 to travel the vehicle.

  Further, the control device 22 controls discharge power and charge power for the battery 15. When the discharge of the battery 15 is controlled, the discharge allowable power Wout is set. The control device 22 controls the discharge of the battery 15 so that the discharge power does not exceed the discharge allowable power Wout. As will be described with reference to FIG. 2, discharge allowable power Wout is determined according to the SOC of battery 15 and the battery temperature. Further, in the “evacuation traveling” described above, the discharge allowable power Wout of the battery is reduced and set as the evacuation traveling base power Wout_md determined according to the SOC and the battery temperature as the set value for evacuation traveling.

  FIG. 2 is a diagram illustrating a method of setting discharge allowable power Wout from a map according to battery temperature and SOC in the embodiment. Discharge allowable power Wout is obtained using a map showing a preset relationship using the calculated current SOC and the detected temperature of battery 15. Therefore, as shown in FIG. 2, a map showing the relationship among the SOC, the battery temperature, and the discharge allowable power Wout is stored in advance in the storage unit of the control device 22. In FIG. 2, a plurality of battery temperatures are defined by a plurality of columns arranged in the horizontal direction, and a plurality of SOCs are defined by a plurality of rows arranged in the vertical direction. In FIG. 2, each frame uniquely determined from the battery temperature and the SOC is blank, but actually, the value of the allowable discharge power Wout is included in each frame. Thereby, discharge allowable power Wout according to battery temperature and SOC is calculated. For example, when the battery temperature is −10 ° C. and the SOC is 50%, the numerical value in the frame indicated by the tips of arrows α and β in FIG. 2 is the discharge allowable power Wout. Further, when the battery temperature and the SOC are numerical values not shown in FIG. 2, the numerical values of the discharge allowable power Wout corresponding to each other are obtained by linear interpolation using two numerical values shown in FIG. 2 on both sides of the numerical values. Calculated. The map shown in FIG. 2 stores a plurality of maps for EV travel, HV travel, and evacuation travel base power, and each map is different.

  Specifically, in the EV and HV travel maps, when the battery temperature and the SOC are the same, the EV base power Wout_base (FIG. 4), which is the discharge allowable power for EV travel, is the discharge for HV travel. It is basically higher than Wout_hv (FIG. 4), which is the allowable power. The EV base power Wout_base and the HV running power Wout_hv match only at both ends of a line indicating each power as shown in FIG. Further, in the maps of the HV traveling and the evacuation traveling base power, the HV traveling power Wout_hv (FIG. 4) is the discharge allowable power of the evacuation traveling base when the battery temperature and the SOC are the same. Basically higher than the base power Wout_md. The HV travel power Wout_hv and the evacuation travel base power Wout_md coincide with each other only at both ends of a line indicating each power as shown in FIG. Therefore, the discharge allowable power Wout from the battery 15 is larger during EV travel than during HV travel. Thereby, traveling performance at the time of EV traveling can be improved. Further, during HV traveling, discharge allowable power Wout from battery 15 is larger than base power during retreat traveling. Thereby, at the time of evacuation traveling, the discharge allowable power can be suppressed and the travelable distance can be increased.

  Further, the control device 22 determines the set value for retreat travel based on the retreat travel base when it is determined that the required discharge power for the battery 15 is increased from the accelerator opening and the vehicle speed, which are the operation amount of the accelerator pedal, during retreat travel. The power is set higher than Wout_md. Specifically, at this time, control device 22 increases the set value for evacuation travel according to the SOC and the battery temperature as compared to when it is not determined that the required discharge power has increased during the evacuation travel. As a result, as will be described later, when the required discharge power is increased due to a request from the user during retreat travel, performance of retreat travel can be ensured.

  As a map, the relationship among the SOC, the temperature of the battery 15, and Wout can be shown in a three-axis space including the orthogonal x-axis, y-axis, and z-axis.

  FIG. 3 is a diagram illustrating a flowchart for explaining a method of setting the discharge allowable power Wout when the vehicle shifts to the retreat travel during the EV travel in the embodiment.

  The setting method of discharge allowable power Wout shown in FIG. 3 is executed as a pre-stage treatment when setting discharge power. For example, the discharge power is set so as not to exceed the set allowable discharge power Wout in each of the “travel trips” that are a plurality of system activation states. Each traveling trip means a state from Ready On to Ready Off. A program for executing the flowchart shown in FIG. 3 is stored in the storage unit of the control device 22 and is executed when the control device 22 is activated.

  When the control device 22 is activated by the user's turning-on operation of the start switch (becomes Ready ON state), in step S10, it is determined whether or not the control device 22 is “during retreat travel from EV travel”. For example, during EV traveling, when a signal notifying the abnormality of the engine 50 is input to the control device 22, the vehicle shifts to retreat traveling. Further, during EV traveling, a signal notifying that an abnormality has occurred in the charging system 14 is input to the control device 22, for example, a signal notifying the abnormality from a sensor or the like that detects the state of the first MG 16 is input to the control device 22. It shifts to evacuation driving. Hereinafter, step S is simply referred to as S.

  If the determination result in step S10 is YES, that is, if it is determined that the vehicle is running away from EV travel, it is determined in S12 whether or not the SOC is greater than a predetermined value. If the determination result in S12 is YES, the process proceeds to S13. In S13, it is determined whether or not the accelerator opening is larger than the predetermined opening and the vehicle speed is lower than the predetermined speed. If the determination result in S13 is YES, it is determined that the required discharge power for the battery 15 has increased from the accelerator opening and the vehicle speed (S16). For example, when the vehicle speed is extremely low although the accelerator opening is large when the vehicle is climbing, the driving force of the second MG 18 is small with respect to the load applied to the vehicle. In this case, it is desirable to increase discharge allowable power Wout as the set value for evacuation travel to increase the driving force of second MG 18.

  Therefore, next, in S17, discharge allowable power Wout is set to EV base power Wout_base (FIG. 4). The EV base power Wout_base is basically higher than the evacuation travel base power Wout_md (FIG. 4), which is the discharge allowable power when it is not determined that the required discharge power has increased during the evacuation travel, with respect to the value according to the SOC and the battery temperature. . As a result, when the required discharge power is increased due to a request from the user during retreat travel, the discharge permissible power Wout can be increased to ensure retreat travel performance.

  If the determination result in S13 is NO, the process proceeds to S14. In S14, the rate of increase in the accelerator opening over time, that is, the amount of increase in the accelerator opening per unit time is larger than the predetermined increase rate, and the time change rate of the vehicle speed, ie, the amount of change in the vehicle speed per unit time. Whether it is 0 or less is determined. For example, when joining the main road from outside the main road on a highway, if the vehicle speed does not increase or decrease despite the rapid increase in accelerator opening, The driving force of the second MG 18 has not increased. Also in this case, it is desirable to increase the driving force of the second MG 18 by increasing the discharge allowable power Wout.

  In this case, the discharge allowable power Wout is set to the EV base power Wout_base in S17 as in the case where the determination result in S13 is YES. As a result, the discharge allowable power Wout can be increased to ensure retreat travel.

  On the other hand, when the determination result in S12 is NO, that is, when the SOC is equal to or less than a predetermined value, it is not desirable in terms of battery performance to increase the discharge allowable power. For this reason, the discharge allowable power Wout is set to the retreat travel base power Wout_md as the next process (S15). The retreat travel base power Wout_md is basically lower than the EV base power Wout_base. Further, when the determination result of S14 is NO, it is not determined that the required discharge power has increased, and the discharge allowable power Wout is set to the evacuation travel base power Wout_md, similarly to the case where the determination result of S12 is NO. (S15). When the determination result of S10 is NO and after the setting of S15 or S17, the setting of the discharge allowable power Wout is completed, and the process returns to S10.

  According to the battery control system described above, when the required discharge power increases due to a request from the user during retreat travel, the discharge permissible power Wout as the set value for retreat travel can be increased to ensure the performance of retreat travel. FIG. 4 shows an example in which the set value of the discharge allowable power Wout varies according to the traveling state when the retreat traveling condition is satisfied, with the battery temperature being constant, in relation to the change in the SOC that is the charge capacity ratio. FIG. In FIG. 4, the battery temperature is described as being constant for easy understanding. However, when the battery temperature actually changes, the map showing the relationship between the changed battery temperature and the SOC. To allow discharge allowable power Wout.

  In the example of FIG. 4, first, the SOC and the discharge allowable power Wout are set at the operating point C1 during EV traveling. At this time, discharge allowable power is EV base power Wout_base. At this time, if a condition for shifting to retreat travel is established due to an engine abnormality or the like, the operating point moves to C2, the discharge allowable power decreases, and the retreat travel set value is set as retreat travel base power Wout_md. Thereby, the vehicle performs the retreat travel driven by the second MG 18 using the power that maximizes the low retreat travel base power Wout_md. Then, as the SOC decreases as the second MG 18 is driven, the operating point moves from C2 to C3 on the line indicating the retracted travel base power Wout_md.

  When it is determined in C3 that the required discharge power has increased due to a request from the user (S16 in FIG. 2), the operating point moves to C4 and the discharge allowable power Wout increases to the EV base power Wout_base. Accordingly, when the required discharge power is increased due to a request from the user during the evacuation traveling, the performance of the evacuation traveling can be secured. Thereafter, as the SOC decreases, the operating point moves from C4 to C5 on the line indicating the EV base power Wout_base. When it is determined that the required discharge power has not increased in C5, the discharge allowable power Wout gradually decreases with time while decreasing the SOC, and becomes the retreat travel base power Wout_md again. Discharge allowable power Wout may be instantaneously reduced when moving from C5 to C6. On the other hand, the allowable discharge power may be gradually changed in the same manner as when moving from C5 to C6 when moving from C1 to C2 or when moving from C3 to C4. Further, as shown in FIG. 4, discharge allowable power Wout is set in a discharge power permission region in which a lower limit is set with a predetermined amount of SOC more than a non-dischargeable region determined from battery performance.

  In the flowchart of FIG. 3, the method for setting the discharge allowable power in the case of shifting to the retreat travel during EV travel has been described. At this time, as described above, when it is determined in S16 of FIG. 3 that the required discharge power has increased, the discharge allowable power Wout is set to the same EV base power Wout_base in S17 as in normal EV travel. The On the other hand, when transitioning to retreat travel during HV travel, discharge allowable power Wout may be set using a flowchart different from FIG. For example, in response to the determination that the required discharge power has increased in S16 of FIG. 3, in the process corresponding to S17, the discharge allowable power Wout is the same HV travel power Wout_hv as in normal HV travel (FIG. 4). Set to As a result, the discharge allowable power Wout when it is determined that the required discharge power has increased is lower than when shifting to the retreat travel during EV travel. For example, in FIG. 4, the operating point moves from a point C3 to a point C4a on a line indicating the HV traveling power Wout_hv. The flowchart of FIG. 3 and the flowchart showing the method for setting the discharge allowable power in the case of transition from HV traveling to retreat traveling can be executed in parallel.

  In FIG. 3 and FIG. 4 described above, when it is determined that the required discharge power is increased in the case of transition to retreat travel during EV travel, the set value for retreat travel is the same as the map during normal EV travel. Is set to EV base power Wout_base. On the other hand, as another example, in the case of transition from EV travel to retreat travel, when it is determined that the required discharge power has increased during retreat travel, another map different from the map during normal EV travel is used. Discharge allowable power Wout may be set. For example, in another map, when it is determined that the required discharge power has increased when the battery temperature and the SOC are the same, the set value for retreat travel is higher than the retreat travel base power Wout_md, but the EV base power Wout_base It may be lower.

  As another example, when shifting to retreat travel, the set value for retreat travel is not determined according to the SOC and battery temperature, but at a vehicle speed generally considered appropriate during retreat travel, for example, 40 km / h. You may set to the 1st fixed value which can drive | work a flat ground. Then, when it is determined that the required discharge power has increased during retreat travel, the retreat travel set value may be set to a second fixed value higher than the first fixed value.

  DESCRIPTION OF SYMBOLS 10 Hybrid vehicle, 12 Battery control system, 14 Charging system, 15 Battery, 16 1st motor generator (1st MG), 17 Power distribution mechanism, 18 2nd motor generator (2nd MG), 22 Control apparatus, 23 System main relay, 24 step-up / down DC / DC converter, 25 inverter, 30 accelerator opening sensor, 31 vehicle speed sensor, 32 current sensor, 33 voltage sensor, 34 temperature sensor, 50 engine, 52 wheels.

Claims (1)

An electric motor and a generator connected to the battery, and an engine;
A battery control system for a hybrid vehicle that travels using one or both of the electric motor and the engine as a drive source,
A control device for controlling discharge power to the battery;
A charging system for transmitting the driving force of the engine to a generator and charging the battery by supplying the battery with the power generated by the generator;
The controller is
When an abnormality occurs in the engine or the charging system, the driving of the engine and the charging of the battery are prohibited, and the electric motor is driven by setting the discharge allowable power of the battery to the set value for retreat travel. The retreat travel set value is determined when it is determined that the required discharge power for the battery has increased from the operation amount of the acceleration instruction unit and the vehicle speed during the retreat travel. A battery control system for a hybrid vehicle, which is higher than when it is not determined that the required discharge power has increased during retreat travel.

Images