JP2013027065A - Regeneration control device of electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a regeneration control device of an electric vehicle which can prevent deterioration of a battery by changing over control of regenerative power generation based on the temperature of the battery and restrain an uncomfortable feeling of a driving feeling of a driver, and suppresses large variation of regenerative current and regenerative torque when battery voltage rises up to the vicinity of the upper limit.SOLUTION: In this regeneration control device of an electric vehicle which controls regenerative power generation of a motor generator when the battery voltage of a battery device reaches an upper-limit value, the battery temperature, the battery voltage and an SOC (state of charge) of the battery device are monitored (S1); when the battery temperature is lower than a threshold value, regenerative current to be carried to the battery device is calculated from a map based on the battery voltage (S2, S3); when the battery temperature is not lower than the threshold value, the regenerative current to be carried to the battery device is calculated based on the SOC (S2, S4); and regenerative torque is controlled so as not to exceed the calculated regenerative current (S5).

Description

  The present invention relates to a regeneration control device for an electric vehicle.

  An electric vehicle such as an electric vehicle (EV) or a hybrid vehicle (HEV, PHEV) is rotated by a battery device having a plurality of storage batteries (secondary batteries; hereinafter referred to as a battery) and supply of electric power from the battery device. And a driving wheel is driven by using the motor as a power source. In such an electric vehicle, at the time of braking, the driving wheel is braked with the regenerative torque of the motor, the motor is generated using the torque of the driving wheel, and the generated electric power is charged in the battery. Regenerating.

JP 2005-033981 A

  In the electric vehicle described above, during regeneration, the regenerative current is controlled so as not to exceed the upper limit voltage of the battery voltage in order to prevent overcharging of the battery. For example, as shown in FIG. 10, at the time of braking, a regenerative current that flows through the battery is generated by the motor, but the maximum regenerative current that can flow is used until the battery voltage reaches the upper limit voltage Vu. Is done. When braking continues intermittently, the battery voltage also increases, and the regenerative current is reduced at time t when the battery voltage reaches the upper limit voltage Vu. In FIG. 10, one pulse indicates one braking, and the widths of the pulses are all the same to simplify the drawing.

  Among batteries used in battery devices, there are batteries having relatively good input characteristics (charging characteristics), but the regenerative current to be reduced is relatively large in batteries having such characteristics. Since such a battery has good input characteristics, the regenerative current acceptability does not change from the initial input even near full charge, and the battery voltage rises greatly during one braking. Therefore, when the regenerative power generation is controlled so as not to exceed the upper limit voltage Vu of the battery voltage, as shown in FIG. 10, the regenerative power generation amount is greatly reduced at a time at the time t when the battery voltage reaches the upper limit voltage Vu. As a result, the regenerative current to be reduced increases.

  If the regenerative current is reduced during regenerative braking, the regenerative torque is also reduced in accordance with the current decrease (regeneration torque is lost), and as a result, the braking force is reduced due to torque loss. When the regenerative current that is reduced during regenerative braking is large, the regenerative torque, that is, the braking force, is also greatly reduced. Therefore, when the driver is operating the foot brake during regenerative braking, the torque is lost. The driver feels uncomfortable with the brake feeling, and the driver feels that the braking force has decreased despite the fact that the brake pedal was depressed with a constant force.

  The present invention has been made in view of the above problems, and by switching the control of regenerative power generation based on the battery temperature, it is possible to prevent battery deterioration and to prevent the driver from feeling uncomfortable, and the battery voltage is limited to an upper limit. An object of the present invention is to provide a regeneration control device for an electric vehicle that suppresses large fluctuations in the regenerative current and the regenerative torque when increasing to the vicinity.

The regenerative control device for an electric vehicle according to the first invention for solving the above-mentioned problems is
A motor generator for regenerative power generation by braking the drive wheels of the electric vehicle;
A battery to which regenerative power generated by the motor generator is supplied;
Temperature detecting means for detecting the temperature of the battery;
Voltage detecting means for detecting a voltage value of the battery;
Charging rate detecting means for detecting the charging rate of the battery;
In a regenerative control device for an electric vehicle comprising: control means for controlling regenerative power generation of the motor according to the state of the battery;
The control means sets the regenerative current supplied to the battery based on the voltage value of the battery when the temperature of the battery is less than a predetermined value, and based on the charging rate when the temperature is equal to or higher than the predetermined value. It is characterized by switching to do.

A regeneration control device for an electric vehicle according to a second invention for solving the above-described problems is
In the regeneration control device for an electric vehicle according to the first invention,
The control means increases the regenerative current as the battery temperature increases.

An electric vehicle regeneration control device according to a third aspect of the present invention for solving the above-described problems is provided.
In the regeneration control device for an electric vehicle according to the second invention,
The control means increases the rate of increase of the regenerative current calculated based on the charging rate with respect to the battery temperature greater than the rate of increase of the regenerative current calculated based on the voltage value with respect to the battery temperature. Features.

  According to the present invention, the battery temperature of the battery device is monitored, and the regenerative current that flows through the battery device is calculated based on the voltage value of the battery when the battery temperature is lower than the predetermined threshold value, and the battery temperature is equal to or higher than the predetermined threshold value. Since the regenerative torque is controlled so that the calculated regenerative current is not exceeded, the regenerative current change during braking and the regenerative operation when the battery voltage increases to near the upper limit are calculated. The change in torque can be reduced. As a result, the uncomfortable feeling of the brake feeling can be eliminated. In addition, in a region where the battery temperature is low (region below a predetermined threshold), the regenerative current is calculated based on the battery voltage that is highly responsive to charging. In regions where the battery temperature is high (regions above a predetermined threshold), the regenerative current is calculated based on the battery charge rate, which is not very responsive to charging. can do.

It is a schematic block diagram which shows the regeneration control apparatus of the electric vehicle which concerns on this invention. 3 is a flowchart illustrating an example of control in a regeneration control device for an electric vehicle shown in FIG. 1. It is a time chart which shows an example of the change of the battery voltage by the control shown in FIG. 2, the regenerative current, and the regenerative torque. 3 is a time chart showing another example of changes in battery voltage, regenerative current and regenerative torque by the control shown in FIG. 2. 3 is a time chart showing another example of changes in battery voltage, regenerative current and regenerative torque by the control shown in FIG. 2. It is an example of the map used by the control (step S3) shown in FIG. It is an example of the map used by the control (step S4) shown in FIG. It is another example of the map used by the control (step S3) shown in FIG. It is another example of the map used by the control (step S4) shown in FIG. It is a time chart which shows the change of the battery voltage by the conventional regeneration control, regeneration current, and regeneration torque.

  Hereinafter, with reference to FIGS. 1-9, embodiment of the regeneration control apparatus of the electric vehicle which concerns on this invention is described. The electric vehicle regeneration control device according to the present invention will be described using an electric vehicle as an example. However, the electric vehicle regeneration control device is not limited to an electric vehicle but can be applied to an electric vehicle such as a hybrid vehicle.

Example 1
FIG. 1 is a schematic configuration diagram showing a regeneration control device for an electric vehicle according to the present embodiment, and FIG. 2 is a flowchart for explaining control in the regeneration control device for an electric vehicle shown in FIG. 5 is a time chart showing changes in battery voltage, regenerative current and regenerative torque by the control shown in FIG. 2, and FIGS. 6 to 9 are maps used in the control shown in FIG.

  In this embodiment, the vehicle 10 is an electric vehicle. The vehicle 10 has left and right front wheels 11L and 11R and left and right rear wheels 12L and 12R. The front wheels 11L and 11R are provided with brake devices 13L and 13R, respectively. The rear wheels 12L and 12R also have brake devices respectively. 14L and 14R are provided.

  In this embodiment, the vehicle 10 is a rear wheel drive, and the rear wheels 12L and 12R are mechanically connected to a motor (motor generator) 16 via a gear box 15, and by rotating the motor 16, The rear wheels 12L and 12R are driven. The motor 16 also functions as a generator. Note that “Fr” in FIG. 1 indicates the front of the vehicle, and here, the configuration of the rear wheel drive is illustrated, but the configuration of the front wheel drive or the configuration of four wheel drive may be used.

  The motor 16 is electrically connected to a battery device (battery) 18 via an inverter 17 that performs DC-AC conversion and a power cable 20, and power from the battery device 18 passes through the inverter 17 and the power cable 20. To be supplied to the motor 16. An ECU (Electronics Control Unit) 19 for instructing motor torque is connected to the inverter 17. The battery device 18 includes a plurality of batteries, and outputs the battery temperature, regenerative current, battery voltage, SOC (State of Charge), and the like to the ECU 19.

  The ECU 19 includes, as hardware, a CPU (microcomputer) that performs calculation, a ROM (read only memory) that serves as a storage area for a control program, a RAM (random access memory) that serves as an operation area for the control program, and various signals. The I / O interface etc. which perform the input / output of these are comprised, and it has a control program which performs predetermined | prescribed control as software.

  For example, when the vehicle 10 travels, the ECU 19 instructs the inverter 17 of an appropriate travel torque according to the vehicle speed, the opening degree of an accelerator pedal (not shown), and the like, and outputs the instructed travel torque. As described above, the electric power supplied from the battery device 18 is used to rotate the motor 16 to drive the rear wheels 12L and 12R.

  On the other hand, when the vehicle 10 is braked, the ECU 19 controls the brake devices 13L, 13R, 14L, and 14R according to the depression amount of a brake pedal (not shown) and the like so that the front wheels 11L and 11R and the rear wheels 12L and 12R are controlled. Although braking is performed, the regenerative torque of the motor 16 is also used to brake the rear wheels 12L and 12R. At this time, the torque of the rear wheels 12L and 12R, which are drive wheels, is used to generate power by the motor 16, and the generated power (regenerative power) is supplied to the battery device 18 via the inverter 17 and the power cable 20. As a result, regenerative power generation is performed. There are two types of regenerative torque, one corresponding to the amount of depression of the brake pedal (brake pedal regeneration) and one corresponding to engine braking in an engine vehicle (engine brake regeneration).

  In the regenerative control device for an electric vehicle according to this embodiment, when the battery voltage of the battery device 18 reaches the upper limit voltage, the regenerative torque of the motor 16 is limited to limit the regenerative current flowing through the battery device 18. The ECU 19 monitors the state (battery temperature, battery voltage, SOC) of the battery device 18 in order to suppress large fluctuations in the regenerative torque during regenerative braking when the regenerative current is limited, and regenerates according to the state. The current is obtained, and the regenerative torque of the motor 16 is controlled so as not to exceed the regenerative current. Such control will be described with reference to the flowchart of FIG. 2, the time charts of FIGS. 3 to 5, and the maps of FIGS. 6 to 9 together with FIG. 1. 3 to 5, one pulse indicates one braking, and the widths of the pulses are all the same for the sake of simplicity. For comparison, a conventional time chart of regenerative current and regenerative torque is shown by dotted lines.

  First, the battery temperature, battery voltage, and SOC output from the battery device 18 are monitored (step S1). Regarding the battery temperature and battery voltage, for example, a monitoring unit (temperature detection means, voltage detection means) for measuring the battery temperature and battery voltage of the battery device 18 is provided in the battery device 18, and the battery temperature is sent from the monitoring unit to the ECU 19. The battery temperature and the battery voltage of the battery device 18 are monitored by outputting the battery voltage. Further, the battery temperature and battery voltage of the battery device 18 may be directly monitored by the ECU 19 (temperature detection means, voltage detection means). Further, the SOC of the battery device 18 correlates with the battery voltage. For example, in the monitoring unit (charge rate detection means), the SOC is calculated from the measured battery voltage, and the ECU 19 sends the SOC to the ECU 19. The SOC of the battery device 18 is monitored by outputting the SOC. Alternatively, the SOC of the battery device 18 may be monitored by the ECU 19 (charging rate detection means) itself by calculating the SOC from the battery voltage output from the battery device 18 to the ECU 19.

  It is confirmed whether the output battery temperature is equal to or higher than a predetermined threshold T. If the battery temperature is lower than the predetermined threshold T, the process proceeds to step S3. If the output battery temperature is equal to or higher than the predetermined threshold T, the process proceeds to step S4 (step S2). ).

  When the battery temperature is lower than the predetermined threshold T, the regenerative current with respect to the battery voltage from the regenerative current map with respect to the battery voltage shown in FIG. 6 or the 3D map of the regenerative current with respect to the battery voltage and the battery temperature shown in FIG. A regenerative current with respect to the battery voltage and the battery temperature is calculated (step S3). The calculated regenerative current means the maximum current value (upper limit value) that can flow under the condition.

  In the map shown in FIG. 6, the regenerative current with respect to the battery voltage is substantially constant when the battery voltage is less than a predetermined value (for example, less than half of the upper limit voltage), but the battery voltage is greater than or equal to the predetermined value. In this case, the regenerative current is reduced as the battery voltage increases. This is because when the battery voltage is less than a predetermined value (less than half of the upper limit voltage), even if sufficient charging power is supplied to the battery device 18, the upper limit voltage of the battery device 18 is not reached. This is because the battery device 18 can be charged more efficiently by supplying as much regenerative power as possible. Therefore, when the battery voltage is less than a predetermined value, it may be prohibited to reduce the regenerative current as the battery voltage increases.

  In the 3D map shown in FIG. 8, the regenerative current with respect to the battery voltage is substantially constant when the battery voltage is less than a predetermined value, but increases when the battery voltage is greater than or equal to the predetermined value. Accordingly, the regenerative current is reduced. Further, the regenerative current with respect to the battery temperature is low when the battery temperature is low, but the regenerative current is also increased as the battery temperature increases. The SOC described later is a value that correlates with the battery voltage, but the rate of change of the regenerative current with respect to the battery voltage is larger than the rate of change of the regenerative current with respect to the SOC.

  On the other hand, when the battery temperature is equal to or higher than the predetermined threshold T, the regenerative current or SOC with respect to the SOC from the regenerative current map with respect to SOC shown in FIG. 7 or the 3D map of the regenerative current with respect to SOC and battery temperature shown in FIG. The regenerative current with respect to the battery temperature is calculated (step S4). The calculated regenerative current means the maximum current value (upper limit value) that can flow under the condition.

  In the map shown in FIG. 7, the regenerative current with respect to the SOC is substantially constant when the SOC is less than a predetermined value (for example, less than half the full charge), but when the SOC is greater than or equal to the predetermined value, As the value increases, the regenerative current is reduced. This is because when the SOC is less than a predetermined value (less than half of the full charge), even if sufficient charging power is supplied to the battery device 18, the upper limit voltage of the battery device 18 is not reached. This is because the battery device 18 can be charged more efficiently by supplying as much regenerative power as possible. Therefore, when the SOC is less than the predetermined value, it may be prohibited to reduce the regenerative current as the SOC increases.

  In the 3D map shown in FIG. 9, the regenerative current with respect to the SOC is substantially constant when the SOC is less than the predetermined value, but when the SOC is greater than the predetermined value, the regenerative current increases as the SOC increases. The current is reduced. Further, the regenerative current with respect to the battery temperature is low when the battery temperature is low, but the regenerative current is also increased as the battery temperature increases.

  Then, the regenerative torque of the motor 16 is instructed to the inverter 17 so as not to exceed the calculated regenerative current (step S5).

  At this time, when the battery temperature is lower than the predetermined threshold T, basically, the regenerative current is changed according to the battery voltage of the battery device 18, and when the battery voltage is equal to or higher than the predetermined value, the battery voltage is The regenerative current is reduced as it increases. When such control is performed, as shown in the time chart portion up to time t1 in FIG. 3 or as shown in FIG. 4, the battery voltage increases each time regeneration is performed, but the battery voltage exceeds a predetermined value. In this case, as the battery voltage increases, the regenerative current is reduced and decreased.

  On the other hand, when the battery temperature is equal to or higher than the predetermined threshold T, basically, the regenerative current is changed according to the SOC of the battery device 18, and when the SOC is equal to or higher than the predetermined value, the SOC increases. The regenerative current is reduced. When such control is performed, as shown in the time chart portion of time t1 to t2 in FIG. 3 or as shown in FIG. 5, the battery voltage increases every time regeneration is performed, but in response to the increase in battery voltage, Therefore, when the SOC is greater than or equal to a predetermined value, the regenerative current is reduced and reduced as the SOC increases.

  Whether the battery temperature is lower than the predetermined threshold T or the battery temperature is higher than or equal to the predetermined threshold T, when considering the battery temperature, the regenerative current is increased as the battery temperature increases. ing. Thereby, an optimal regenerative current can be generated corresponding to the battery temperature. Further, considering the battery temperature in order to calculate the regenerative current, it is possible to perform suitable charging and to suppress the deterioration of the battery.

  Then, during the time (time t2 or t) when the battery voltage reaches the upper limit voltage Vu, since the regenerative current has already been reduced, there is no need to greatly reduce the regenerative current at once as in the conventional case. As a result, the regenerative current can be controlled so that the battery voltage does not exceed the upper limit voltage Vu, and the change in regenerative current and the change in regenerative torque when the battery voltage increases to near the upper limit are reduced. The uncomfortable feeling of the ring can be eliminated.

  Here, the time chart according to the control of the present embodiment will be described by dividing the range in which the battery temperature changes.

(1) When the range in which the battery temperature changes is a range before and after the predetermined threshold T First, when the battery temperature is lower than the predetermined threshold T, that is, a time chart up to time t1 in FIG. In this portion, the regenerative current is controlled based on the battery voltage, or the battery voltage and the battery temperature, and the regenerative current is reduced as the battery voltage increases even during one braking operation. The regenerative current also decreases in one pulse indicating the braking of. Even during one braking, the regenerative current is calculated based on the changed battery voltage using the map shown in FIG. 6 or the 3D map shown in FIG. 8, and the regenerative current is changed according to the change in the battery voltage. Just do it.

  In addition, a series of regenerative control may be performed by performing regenerative power generation a plurality of times, and the reduction rate of the regenerative current in each regenerative power generation in a plurality of regenerative power generations may be made constant. Furthermore, the regenerative current may be the same as the regenerative current at the end of the previous time and the regenerative current at the start of the next time. When such control is performed, the regenerative current is throttled at a constant decrease rate, so that the uncomfortable feeling of brake feeling during one braking can be eliminated. Furthermore, in regenerative braking performed continuously, the driver's uncomfortable feeling can be alleviated by making the regenerative current at the end of the previous braking the same as the regenerative current at the start of the next round. .

  On the other hand, when the battery temperature is equal to or higher than the predetermined threshold T, that is, in the time chart portion of time t1 to t2 in FIG. 3, at the start of braking, the map shown in FIG. 7 or FIG. Using the 3D map, the regenerative current is calculated based on the SOC of the battery device 18 or the SOC and the battery temperature, and the regenerative current is kept constant as it is during one braking. This is because even if the regenerative current is supplied to the battery device 18, the regenerative current during one braking is made constant in consideration of the fact that it is not immediately reflected in the SOC (the response of the SOC change is bad). This is because it is preferable. In this case, the regenerative current is constant during one braking, but the regenerative current is reduced and reduced according to the increase in SOC due to the increase in battery voltage due to regeneration, so that the battery voltage becomes the upper limit voltage Vu. At the reaching time t2, the regenerative current is already decreasing, and the change in the regenerative current and the change in the regenerative torque at that time are reduced, so that the uncomfortable feeling of the brake feeling can be eliminated.

  As described with reference to FIG. 3, by switching the regenerative current calculation means depending on the battery temperature of the battery device 18, suitable control can be performed. That is, in the region where the battery temperature of the battery device 18 is low (the region where the battery temperature is less than the predetermined threshold value T), the regenerative current is calculated based on the battery voltage that is highly responsive to charging, and thus exceeds the upper limit voltage Vu of the battery voltage. Thus, deterioration of the battery device 18 can be suppressed. In addition, in a region where the battery temperature of the battery device 18 is relatively high (region where the predetermined threshold value T is equal to or higher than the threshold value T), the regenerative current is calculated on the basis of the SOC that is not very responsive to charging. Can be controlled constantly.

  8 and 9, when the battery temperature of the battery device 18 is less than the predetermined threshold T, the regenerative current is calculated based on the battery voltage and the battery temperature, and the battery temperature is equal to or higher than the predetermined threshold T. In this case, the regenerative current is calculated based on the SOC and the battery temperature. The rate of increase of these regenerative currents with respect to the battery temperature is made larger when the regenerative current is calculated using the SOC than when the regenerative current is calculated using the battery voltage. This is because when the regenerative current is calculated using the battery voltage in a region where the battery temperature is low (region below the predetermined threshold T), the increase rate of the regenerative current with respect to the temperature is increased because the battery temperature is low. This is because the possibility of exceeding the upper limit voltage Vu is increased.

(2) When battery temperature changes within a range below a predetermined threshold T When the battery temperature is below a predetermined threshold T, that is, in FIG. 4, the battery voltage or the battery voltage and the battery The regenerative current is controlled based on the temperature, and even during one braking, the regenerative current is reduced as the battery voltage rises. Therefore, the regenerative current is reduced even in one pulse indicating one braking. I will do it. In this case, even when the battery voltage reaches the upper limit voltage Vu when traveling on a long downhill, the regenerative current has already decreased at the time t when the battery voltage reaches the upper limit voltage Vu. This is a state, and the change in the regenerative current and the change in the regenerative torque are reduced. Even during one braking, the regenerative current is calculated based on the changed battery voltage using the map shown in FIG. 6 or the 3D map shown in FIG. 8, and the regenerative current is changed according to the change in the battery voltage. Just do it.

  In addition, a series of regenerative control may be performed by performing regenerative power generation a plurality of times, and the reduction rate of the regenerative current in each regenerative power generation in a plurality of regenerative power generations may be made constant. Furthermore, the regenerative current may be the same as the regenerative current at the end of the previous time and the regenerative current at the start of the next time. When such control is performed, the regenerative current is throttled at a constant decrease rate, so that the uncomfortable feeling of brake feeling during one braking can be eliminated. Furthermore, in regenerative braking performed continuously, the driver's uncomfortable feeling can be alleviated by making the regenerative current at the end of the previous braking the same as the regenerative current at the start of the next round. .

(3) When the range in which the battery temperature changes is a range equal to or higher than the predetermined threshold T When the battery temperature is equal to or higher than the predetermined threshold T, that is, in FIG. Using the map or the 3D map shown in FIG. 9, the regenerative current is calculated based on the SOC of the battery device 18 or the SOC and the battery temperature, and the regenerative current remains constant during the single braking operation. It is said. This is because even if the regenerative current is supplied to the battery device 18, the regenerative current during one braking is made constant in consideration of the fact that it is not immediately reflected in the SOC (the response of the SOC change is bad). This is because it is preferable. In this case, the regenerative current is constant during one braking, but the regenerative current is reduced and reduced according to the increase in SOC due to the increase in battery voltage due to regeneration, so that the battery voltage becomes the upper limit voltage Vu. At the reaching time t, the regenerative current is already decreasing, and the change in regenerative current and the change in regenerative torque at that time are reduced, so that the uncomfortable feeling of brake feeling can be eliminated.

  The regenerative control device for an electric vehicle according to the present invention is suitable for an electric vehicle, but is not limited to an electric vehicle and can also be applied to an electric vehicle such as a hybrid vehicle.

10 vehicle 16 motor (motor generator)
18 Battery device (battery)
19 ECU

Claims (3)

A motor generator for regenerative power generation by braking the drive wheels of the electric vehicle;
A battery to which regenerative power generated by the motor generator is supplied;
Temperature detecting means for detecting the temperature of the battery;
Voltage detecting means for detecting a voltage value of the battery;
Charging rate detecting means for detecting the charging rate of the battery;
In a regenerative control device for an electric vehicle comprising: control means for controlling regenerative power generation of the motor according to the state of the battery;
The control means sets the regenerative current supplied to the battery based on the voltage value of the battery when the temperature of the battery is less than a predetermined value, and based on the charging rate when the temperature is equal to or higher than the predetermined value. A regenerative control device for an electric vehicle, characterized in that switching is performed. The regeneration control device for an electric vehicle according to claim 1,
The regenerative control device for an electric vehicle, wherein the control means increases the regenerative current as the battery temperature increases. In the regeneration control device for an electric vehicle according to claim 2,
The control means increases the rate of increase of the regenerative current calculated based on the charging rate with respect to the battery temperature greater than the rate of increase of the regenerative current calculated based on the voltage value with respect to the battery temperature. A regenerative control device for an electric vehicle characterized by the above.

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