JP6277441B2 - Power control device and power supply system - Google Patents

Description

  The present invention relates to a power control device and a power supply system.

Conventionally, a device using a battery and a capacitor in combination as a power source for a vehicle is known (for example, see Patent Documents 1, 2, 3, 4 and Non-Patent Document 1).
Patent Document 1 Japanese Patent Application Laid-Open No. 2008-61405 Patent Document 2 Japanese Patent Application Laid-Open No. 2010-41847 Patent Document 3 Japanese Patent Application Laid-Open No. 2012-157209 Patent Document 4 Japanese Patent Application Laid-Open No. 2007-181328・ Research on Capacitor Hybrid Power Supply System -Improvement and Control of Half Controlled Converter- ", The University of Tokyo Graduate School Master thesis, submitted on February 8, 2011

  It is desirable to suppress steep output fluctuations in the battery.

In the first aspect of the present invention, there is provided a power control device for controlling power supply from a battery and a capacitor to a load, wherein the limit of the waveform of the load current supplied to the load is limited by a preset limit value. A limiter that generates a current waveform, a filter waveform that limits a band of the limited current waveform based on a preset time constant, and a filter that controls power supplied from the battery to the load based on the filter waveform; Based on the difference between the waveform of the load current and the filter waveform, a difference calculation unit that controls the power supplied from the capacitor to the load, and at least one of the limit value of the limiter and the time constant of the filter based on the operation pattern of the load A setting unit configured to set an evaluation function based on the constraint condition of the remaining capacity of the capacitor and the characteristics of the battery, and the load When operating in emissions, while satisfying the constraints of the capacitor, so evaluation is the highest in the evaluation function, the limiter limits and setting at least one of the time constant of the filter, to provide a power control device.

  According to a second aspect of the present invention, there is provided a power supply system including the power control device, battery and capacitor according to the first aspect.

  The summary of the invention does not enumerate all the features of the present invention. In addition, a sub-combination of these feature groups can also be an invention.

It is a figure showing an example of composition of power supply system 100 concerning an embodiment. 2 is a diagram illustrating a configuration example of a controller 30. It is a figure which shows an example of each waveform of a load current, the battery current which the battery 10 outputs, and the capacitor current which the capacitor 12 outputs. It is a figure which shows the operation | movement pattern which shows the fluctuation | variation of the speed of the vehicle which drive | works in C08 mode. It is a figure which shows the operation | movement pattern which shows the fluctuation | variation of the drive power of the vehicle which drive | works in JC08 mode. It is a figure which shows the integrated value BWdc of the electric power which the battery 10 outputs when electric power is supplied only from the battery 10 to the vehicle which drive | works in JC08 mode. It is a figure which shows the load current which should be supplied to the vehicle which drive | works in JC mode. FIG. 4 is a diagram showing an integrated value BWdc of power output from the battery 10 and an output terminal voltage Vsc of the capacitor 12 when power is supplied from the power supply system 100 described with reference to FIGS. 1 to 3 to a vehicle traveling in the JC08 mode. is there. FIG. 6B is a diagram showing a load current, a battery current, and a capacitor current when electric power is supplied from the electric power supply system 100 to a vehicle traveling in the JC08 mode. 6B is a diagram illustrating an integrated value BWdc of power output from the battery 10 and an output terminal voltage Vsc of the capacitor 12 when the capacity of the capacitor 12 is doubled compared to the example of FIG. 6A. FIG. 6B is a diagram showing a load current, a battery current, and a capacitor current when the capacitance of the capacitor 12 is doubled compared to the example of FIG. 6B. It is a figure which shows the remaining capacity of the battery 10 and the output terminal voltage of the capacitor 12 when the limiter 32 and the filter 34 are set based on the evaluation function. It is a figure which shows the load current, battery current, and capacitor current in the example shown to FIG. 8A. The figure which shows how the average value and peak value of the output current of the battery 10 are fluctuate | varied about each when the capacitor | condenser 12 is used when it operate | moves only with the battery 10, and two capacitors 12 are used in parallel. It is. FIG. 3 is a diagram illustrating a load current, a battery current, and a capacitor current when the limiter 32 and the filter 34 illustrated in FIG. 2 are replaced as a comparative example. 6 is a diagram illustrating another configuration example of the controller 30. FIG. 6 is a diagram illustrating another configuration example of the controller 30. FIG.

  Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention.

  FIG. 1 is a diagram illustrating a configuration example of a power supply system 100 according to the embodiment. The power supply system 100 includes a battery 10, a capacitor 12, an inverter 14, and a power control device 20, and supplies power to a load 200.

  The battery 10 is, for example, a lead battery or a lithium ion battery. The capacitor 12 is a capacitor having a faster response speed than that of the battery 10, for example, a lithium ion capacitor. The storage capacity of the capacitor 12 may be smaller than the storage capacity of the battery 10.

  The load 200 may be, for example, a vehicle that can travel by electricity, may be an industrial machine used in a factory or the like, or may be another electric device. Battery 10 and capacitor 12 are connected in parallel to load 200.

The power control device 20 controls the power output from the battery 10 and the power supply from the capacitor 12 to the load based on the load current I _load supplied to the load 200. The power control unit 20, the output current of the battery 10, the sum equal conditions as the load current I _load in the output current of the capacitor 12, allocates whether to output how much power to the battery 10 and the capacitor 12.

  The power control apparatus 20 of this example includes a battery power control circuit 22, a CAP charge control circuit 24, a CAP power control circuit 26, and a controller 30. The battery power control circuit 22 controls how much power is output from the battery 10. The battery power control circuit 22 of this example is provided between the output end of the battery 10 and the load 200, and supplies the power output to the battery 10 to the load 200.

  The CAP power control circuit 26 controls how much power is output from the capacitor 12. The CAP power control circuit 26 of this example is provided between the output terminal of the capacitor 12 and the load 200, and supplies the power output to the capacitor 12 to the load 200. The CAP charge control circuit 24 supplies the capacitor 12 with at least a part of the current output from the battery 10 when the capacitor 12 is to be charged with the current output from the battery 10.

The controller 30 detects the waveform of the load current I _load by detecting the magnitude of the load current I _load supplied to the load 200 in time series. The controller 30 controls the battery power control circuit 22 and the CAP power control circuit 26 based on the detected load current I _load and assigns how much power is output to the battery 10 and the capacitor 12. The inverter 14 converts the DC power output from the battery 10 and the capacitor 12 into AC power and supplies the AC power to the load 200. For example, the inverter 14 converts DC power into three-phase AC power and drives the motor of the load 200.

FIG. 2 is a diagram illustrating a configuration example of the controller 30. The controller 30 of this example includes a limiter 32 and a filter 34. The limiter 32 generates a limit current waveform in which the waveform of the load current I _load is limited by a preset limit value. The limiter 32 limits the waveform of the load current I _load with a predetermined upper limit value. Further, the limiter 32 may further limit the waveform of the load current I _load with a predetermined lower limit value. The lower limit value may be a negative value in the load current _Iload . In this case, the lower limit value is a limit value of the current regenerated from the load 200 to the battery 10 or the capacitor 12.

  The filter 34 generates a filter waveform in which the band of the limited current waveform is limited based on a preset time constant. For example, the filter 34 is a first-order lag filter. The filter 34 controls the power supplied from the battery 10 to the load 200 based on the generated filter waveform. The filter 34 of this example notifies the battery power control circuit 22 of the generated filter waveform, thereby causing the battery 10 to output a current corresponding to the filter waveform.

  The difference calculation unit 36 controls the power supplied from the capacitor 12 to the load 200 based on the difference between the waveform of the load current detected by the controller 30 and the filter waveform generated by the filter 34. The difference calculation unit 36 in this example notifies the CAP power control circuit 26 of a difference waveform obtained by subtracting the filter waveform from the load current waveform, thereby causing the capacitor 12 to output a current corresponding to the difference waveform.

  FIG. 3 is a diagram illustrating examples of waveforms of the load current, the battery current output from the battery 10, and the capacitor current output from the capacitor 12. In FIG. 3, the horizontal axis represents time, and the vertical axis represents the current value. A region where the current value is positive indicates a state in which current flows from the battery 10 or the capacitor 12 to the load 200, and a region where the current value is negative indicates that current is regenerated from the load 200 to the battery 10 or the capacitor 12. Indicates the state. The waveform of the battery current corresponds to the filter waveform described in FIG. 2, and the waveform of the capacitor current corresponds to the differential waveform described in FIG.

  The load current in this example varies greatly in steps. On the other hand, by limiting the level of the load current with the limiter 32, the fluctuation range of the battery current can be suppressed. Thereby, the maximum output of the battery 10 can be made smaller than the peak of the load current. Further, by limiting the band of the load current with the filter 34, it is possible to suppress a steep fluctuation of the battery current. For this reason, the cost of the large capacity battery 10 can be reduced.

  The capacitor current corresponds to a current that is not covered by the battery current among the load current. The capacitor current in this example covers the peak portion and steep fluctuations in the load current. Capacitor 12 can increase output and speed more easily than battery 10. With such a configuration, it is possible to stably supply power to the load and realize a low-cost power supply system.

  The controller 30 uses the filter 34 to smooth the waveform after limiting the current value with the limiter 32. For this reason, a sharp change in the current waveform due to the limit of the current value by the limiter 32 can be smoothed. For this reason, the burden of the battery 10 can be reduced.

  The lower limit value of the limiter 32 in this example is set to a positive value greater than zero. For this reason, for example, even when the load current is zero as in the section from 30 seconds to 40 seconds in FIG. 3, the battery 10 outputs a current corresponding to the lower limit value. When the battery 10 outputs a battery current larger than the load current, the controller 30 controls the CAP charge control circuit 24 to charge the capacitor 12 with a difference current between the battery current and the load current. Thereby, since the capacitor 12 can be charged in a section where the load current is small, it is possible to prevent the capacitor 12 from becoming empty while stably supplying power to the load 200. Further, the controller 30 of this example charges the capacitor 12 with the regenerative current in a section where the current is regenerated from the load 200. The controller 30 may charge the battery 10 with a regenerative current.

  Further, the limit value of the limiter 32 and the time constant of the filter 34 are set in advance based on the operation pattern of the load 200. The operation pattern of the load 200 refers to, for example, a fluctuation pattern of power consumption of the load 200 during a predetermined period. The variation pattern may be generated based on prediction about the operation of the load 200, may be generated from the contents of an instruction, a program, or the like given to the load 200, and is generated based on the past operation history of the load 200. And may be generated in other ways.

  4A and 4B are diagrams illustrating an example of an operation pattern of the load 200. FIG. The load 200 in this example is a vehicle. FIG. 4A is a diagram showing an operation pattern showing fluctuations in the speed of a vehicle traveling in the so-called JC08 mode, and FIG. 4B is a diagram showing an operation pattern showing fluctuations in driving power of the vehicle running in the JC08 mode. The operation pattern of the load 200 is not limited to the patterns shown in FIGS. 4A and 4B.

  FIG. 5A is a diagram illustrating an integrated value BWdc of electric power output from the battery 10 when electric power is supplied only from the battery 10 to a vehicle traveling in the JC08 mode. FIG. 5B is a diagram illustrating a load current to be supplied to a vehicle traveling in the JC mode. As shown in FIG. 5B, the load current has a large peak.

  6A shows the integrated value BWdc of the power output from the battery 10 and the output terminal voltage Vsc of the capacitor 12 when power is supplied from the power supply system 100 described in FIGS. 1 to 3 to the vehicle traveling in the JC08 mode. FIG. FIG. 6B is a diagram showing a load current, a battery current, and a capacitor current when electric power is supplied from the electric power supply system 100 to a vehicle traveling in the JC08 mode. In FIG. 6B, similarly to FIG. 3, the load current is indicated by a dotted line, the battery current is indicated by a solid line, and the capacitor current is indicated by a one-dot chain line. Note that the waveform of the load current is the same as that shown in FIG. 5B.

  By providing the capacitor 12, the integrated value BWdc of the output power of the battery 10 is lower than in the case of FIG. 5A. Moreover, the peak value of the battery current output from the battery 10 is smaller than in the case of FIG. 5B.

  FIG. 7A is a diagram showing the integrated value BWdc of the power output from the battery 10 and the output terminal voltage Vsc of the capacitor 12 when the capacity of the capacitor 12 is doubled compared to the example of FIG. 6A. FIG. 7B is a diagram showing a load current, a battery current, and a capacitor current when the capacitance of the capacitor 12 is doubled compared to the example of FIG. 6B.

  By doubling the capacitance of the capacitor 12 (or providing two capacitors 12 in parallel), the amount of current that can be covered by the capacitor 12 increases. Thereby, the burden of the battery 10 can be reduced more. In this example, as shown in FIGS. 7A and 7B, the output of the battery 10 has a substantially constant value over the entire section of the operation pattern.

  Note that the limit value of the limiter 32 and the time constant of the filter 34 are preset to optimum values based on an operation pattern as shown in FIGS. 4A and 4B as an example. In this example, the optimum value refers to a value that gives the highest evaluation in a preset evaluation function. The highest evaluation in the evaluation function means that if the evaluation function is a function related to the maximization problem, the value of the evaluation function becomes the maximum value, and if the evaluation function is a function related to the minimization problem, the evaluation function The value of is the minimum value.

本例の評価関数は、動作パターンの期間において、電池電流Ｉ_ＤＣ（ｔ）の最大値（ピーク値）が小さいほど評価が高い関数である。
本例の制約条件は、動作パターンの期間において、キャパシタ電圧Ｖ_ＳＣ（ｔ）が所定の許容範囲Ｖ_{ＳＣ＿ｌｂ}＜Ｖ_ＳＣ（ｔ）＜Ｖ_{ＳＣ＿ｕｂ}で変動する条件である。許容範囲は、キャパシタ１２の仕様等により定められる。なお、Ｖ_ＳＣ（０）はキャパシタ電圧の初期値、Ｉ_ＳＣはキャパシタ電流、Ｃ_ＳＣはキャパシタ１２の容量、Ｒ_Ｃはキャパシタ１２の内部抵抗を指す。当該評価関数および制約条件を用いて、電池電流Ｉ_ＤＣ（ｔ）のピーク値を最小化するθ（リミッタ３２における制限値）を決定する。 As an example, the limit value of the limiter 32 and the time constant of the filter 34 can be determined based on the following evaluation function and constraint conditions.

The evaluation function of this example is a function whose evaluation increases as the maximum value (peak value) of the battery current I _DC (t) decreases during the period of the operation pattern.
Constraints of this example, in the period of the operation pattern is a condition where the capacitor voltage _V SC (t) varies in a predetermined allowable range _{V SC_lb <V SC (t)} <V SC_ub. The allowable range is determined by the specifications of the capacitor 12 and the like. V _SC (0) is the initial value of the capacitor voltage, I _SC is the capacitor current, C _SC is the capacitance of the capacitor 12, and _RC is the internal resistance of the capacitor 12. Using the evaluation function and the constraint condition, θ (a limit value in the limiter 32) that minimizes the peak value of the battery current I _DC (t) is determined.

なお、^Ｉ_ＤＣは、リミッタ３２が出力する制限電流波形を示す。また、Ｔはフィルタ３４の時定数、ｓはラプラス演算子を示す。 The processing in the limiter 32 and the filter 34 can be expressed by the following expression.

Note that ^ I _DC indicates a limited current waveform output from the limiter 32. T represents a time constant of the filter 34, and s represents a Laplace operator.

  If the above evaluation function, constraint condition, and operation pattern are determined, the evaluation by the evaluation function becomes the highest (in the example of Equation 1, the evaluation function is the minimum value). The limit value of the limiter 32 and the optimum time constant of the filter 34 The solution can be determined. For example, all combinations of the limit value of the limiter 32 that can be selected and the time constant of the filter 34 may be evaluated by the evaluation function to determine the optimum solution. Alternatively, the optimal solution may be determined using a known optimization problem solution. In the limiter 32 and the filter 34, the above-described optimal solution is set in advance. Thereby, operation | movement of the electric power supply system 100 can be optimized according to an evaluation function.

本例の評価関数は、動作パターンの終点において、電池１０の残容量が多いほど評価が高い関数である。当該関数は、動作パターンの期間における電池１０の平均出力電流が小さいほど評価が高い関数ともいえる。なお、ＢＣ_ＤＣは、電池１０の残容量を示す。本例では、数４の評価関数が最大値となるθを決定する。 The evaluation function is not limited to the above example. For example, the following evaluation function can also be used.

The evaluation function of this example is a function that has a higher evaluation at the end point of the operation pattern as the remaining capacity of the battery 10 increases. This function can be said to be a function that is evaluated more highly as the average output current of the battery 10 during the operation pattern period is smaller. BC _DC represents the remaining capacity of the battery 10. In this example, θ that maximizes the evaluation function of Equation 4 is determined.

  FIG. 8A is a diagram showing the remaining capacity of the battery 10 and the output terminal voltage of the capacitor 12 when the limiter 32 and the filter 34 are set based on the evaluation function shown in Equation 4. FIG. 8B is a diagram showing a load current, a battery current, and a capacitor current in the example shown in FIG. 8A. By using the evaluation function shown in Equation 4, the remaining capacity of the battery 10 can be maximized.

  FIG. 9 shows how the average value and the peak value of the output current of the battery 10 fluctuate when the battery 10 is operated alone, when the capacitor 12 is used, and when two capacitors 12 are used in parallel. FIG. When the capacitor 12 is used, the evaluation function that minimizes the peak value shown in Equation 1 and the evaluation function that minimizes the average current shown in Equation 4 are shown.

  As shown in FIG. 9, when using an evaluation function that uses one capacitor 12 and minimizes the current peak as compared with the case where the battery 10 is operated alone, the peak current is 1/3 or less and the average The current became 1/2 or less. Further, when the evaluation function using two capacitors 12 and minimizing the current peak was used, the peak current was 1/8 or less and the average current was 1/2 or less. In this example, when the evaluation function that minimizes the average current is used and when the evaluation function that minimizes the peak current is used, there is no significant difference in reducing the average current, and the peak current It is more effective to use an evaluation function that minimizes the peak current. Which evaluation function is used may be appropriately selected according to the operation pattern.

  FIG. 10 is a diagram showing a load current, a battery current, and a capacitor current when the limiter 32 and the filter 34 shown in FIG. 2 are replaced as a comparative example. In other words, the controller 30 of this example limits the band of the load current waveform with the filter 34 and then limits the level with the limiter 32.

  In this case, as shown in FIG. 10, a steep fluctuation component is generated in the portion of the battery current waveform notified by the controller 30 to the battery power control circuit 22 in the portion where the level is limited by the limiter 32. For this reason, the battery 10 is required to have a steep change in battery current, and the burden on the battery 10 increases. Note that, in the example shown in FIG. 3 and the example shown in FIG. 10, the limit value of the limiter 32 and the time constant of the filter 34 are the same.

  FIG. 11 is a diagram illustrating another configuration example of the controller 30. The controller 30 of this example further includes a setting unit 38 in addition to the configuration of the controller 30 shown in FIG. The setting unit 38 sets at least one of the limit value of the limiter 32 and the time constant of the filter 34 based on the operation pattern of the load 200.

  The setting unit 38 receives information indicating an operation pattern, information indicating a constraint condition, and information indicating an evaluation function from a user or the like. The operation pattern is a driving power pattern of the vehicle in the JC08 mode or the like as shown in FIG. 4B, for example. The constraint condition is, for example, an upper limit and a lower limit of the output terminal voltage that the capacitor 12 should maintain. The evaluation function is an evaluation function based on the characteristics of the battery 10, for example, an evaluation function that minimizes the average value of the battery current of the battery 10 or an evaluation function that minimizes the peak value of the battery current.

  The setting unit 38 limits the limit value of the limiter 32 and the time constant of the filter 34 so that the evaluation function becomes the maximum value or the minimum value while satisfying the constraint condition of the capacitor 12 when the load 200 operates in the operation pattern. Set at least one of The setting unit 38 sets the optimum solution for the limiter 32 and the filter 34 so that the evaluation function becomes the maximum value or the minimum value, as described in relation to Expression 1 to Expression 4.

  FIG. 12 is a diagram illustrating another configuration example of the controller 30. The controller 30 of this example further includes a memory 40 in addition to the configuration of the controller 30 shown in FIG. The memory 40 stores a load current waveform detected by the controller 30. The setting unit 38 may update the operation pattern based on the load current history stored in the memory 40.

  For example, in the case where the load 200 is a vehicle, the memory 40 stores information relating to a departure place and a destination specified in the car navigation system of the vehicle and a pattern of a load current supplied to the load 200 in association with each other. . When the same place as the departure place and destination registered in the memory 40 is designated, the setting unit 38 may read the corresponding load current pattern from the memory 40 and use it as an operation pattern. The setting unit 38 sets the limiter 32 and the filter 34 so that the evaluation function becomes the maximum value or the minimum value for the operation pattern.

  The setting unit 38 generates a new operation pattern based on the waveform of the load current when a highly correlated load current waveform periodically appears in the load current waveform stored in the memory 40. Also good. More specifically, when a load current waveform having a correlation value greater than or equal to a predetermined value is repeatedly detected in a certain time zone such as a weekday morning, the setting unit 38 commutes the average value of the load current waveform. As an operation pattern for use, it may be used for the operation of the load 200 in the certain time period. Further, the setting unit 38 may identify the driver of the vehicle by image recognition or the like, and use the operation pattern set for each driver or the set values of the limiter 32 and the filter 34.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

  The order of execution of each process such as operations, procedures, steps, and stages in the apparatus, system, program, and method shown in the claims, the description, and the drawings is particularly “before” or “prior to”. It should be noted that the output can be realized in any order unless the output of the previous process is used in the subsequent process. Regarding the operation flow in the claims, the description, and the drawings, even if it is described using “first”, “next”, etc. for convenience, it means that it is essential to carry out in this order. It is not a thing.

DESCRIPTION OF SYMBOLS 10 ... Battery, 12 ... Capacitor, 14 ... Inverter, 20 ... Power control device, 22 ... Battery power control circuit, 24 ... CAP charge control circuit, 26 ... CAP power Control circuit, 30 ... controller, 32 ... limiter, 34 ... filter, 36 ... difference calculation unit, 38 ... setting unit, 40 ... memory, 100 ... power supply system, 200 ... Load

Claims (4)

A power control device for controlling power supply from a battery and a capacitor to a load,
A limiter that generates a limit current waveform in which a waveform of a load current supplied to the load is limited by a preset limit value;
A filter that generates a filter waveform in which a band of the limited current waveform is limited based on a preset time constant, and that controls power supplied from the battery to the load based on the filter waveform;
A difference calculation unit for controlling power supplied from the capacitor to the load based on a difference between the waveform of the load current and the filter waveform ;
A setting unit configured to set at least one of a limit value of the limiter and a time constant of the filter based on the operation pattern of the load;
The setting unit sets an evaluation function based on a constraint condition of the remaining capacity of the capacitor and a characteristic of the battery, and satisfies the constraint condition of the capacitor when the load operates in the operation pattern, while the evaluation function is satisfied. Set at least one of the limit value of the limiter and the time constant of the filter so that the evaluation in the function is the highest.
Power control unit. The evaluation function is a function in which the evaluation increases as the remaining capacity of the battery increases when the load operates in the operation pattern, or a function in which the evaluation increases as the peak value of the current output from the battery decreases. The power control apparatus according to claim 1 . The setting unit generates an operation pattern based on the operation history of the load, based on the generated the operation pattern according to claim 1, for setting at least one of the time constant limit value and the filter of the limiter or power control device according to 2. An electric power supply system provided with the electric power control apparatus as described in any one of Claim 1 to 3 , the said battery, and the said capacitor.

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