JP2006320069A - Control device for secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To appropriately set amounts of electric energy that can be inputted and outputted to prevent use of a secondary battery under extreme conditions when the accuracy of estimation of a quantity of battery state in a control device for secondary batteries so designed as to estimate a quantity of battery state by parameter identification (learning control) based on a sensor detection value. <P>SOLUTION: A parameter identification unit 110 carries out parameter identification based on a sensor detection value. A quantity of state estimation unit 120 computes quantities of state of a secondary battery using a control parameter Cpr from the parameter identification unit 110. The quantities of state include at least set values Pin, Pout indicating amounts of electric energy that can be inputted and outputted. In initial learning state established before the degree of control parameter identification reaches a predetermined value or higher after a learning reset instruction is inputted, determined by a degree of identification determination unit 130, a path P1 is selected. Therefore, a quantity of state correction unit 140 corrects the set values Pin, Pout so as to limit and reduce the amounts of electric energy that can be inputted and outputted, set by the quantity of state estimation unit 120. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a control device for a secondary battery, and more particularly to input / output power limit control for a secondary battery.

  In recent years, development of vehicles using electric motors such as hybrid cars and electric cars has been actively conducted in consideration of fuel consumption and the environment. In these vehicles, charge / discharge control of the secondary battery that stores the drive power of the electric motor is important. In general, measurable secondary battery data is limited to the terminal voltage, current, temperature, etc. of the battery, so using these detected values, the state of charge (SOC), the input power value Pin and A technique for estimating a state quantity such as the output possible power value Pout is important.

  For example, Japanese Laid-Open Patent Publication No. 6-59003 (Patent Document 1) discloses a configuration of a battery remaining capacity meter that can accurately detect a remaining battery capacity during operation of an electric vehicle. In Patent Document 1, the remaining capacity of the battery is estimated from the V (voltage) -I (current) characteristics in a high load state, and the degree of deterioration is calculated from the SOC calculated by the electric quantity integration method and the remaining capacity. . Then, based on this degree of deterioration, the SOC is calculated by correcting the full charge capacity in the electric quantity integrating method, thereby preventing the occurrence of an error due to the electric quantity integrating method and improving the measurement accuracy of the battery remaining capacity. be able to.

A method for estimating the SOC and input / output possible power values Pin and Pout by applying the applied digital filter theory using the battery terminal voltage, current, temperature, etc. that can be directly measured by the sensor is also proposed. (For example, Non-Patent Document 1).
JP-A-6-59003 Daijiro Yumoto et al., “Method for Estimating Battery Internal State Quantity Using Applicable Digital Filter Theory”, Automobile Society of Japan Academic Lecture Preprint, May 2003, No. 30-03 (200335031), p. 5-10

  In a system equipped with a secondary battery as described above, the timing at which state quantity estimation relating to the secondary battery is initialized inevitably occurs due to maintenance, replacement, or the like. Then, once the state quantity estimation is initialized, there is a concern that the estimation accuracy decreases immediately after that. Therefore, when the input / output power of the secondary battery becomes excessive due to the deterioration of the estimation accuracy, the secondary battery may be used in a usage state, which may adversely affect the battery life.

  On the other hand, in a vehicle such as a hybrid vehicle, since the amount of battery that can be mounted on the vehicle is limited, it is required to draw out the limit performance of the secondary battery. For this reason, there is a tendency to severely set the input / output power limit of the secondary battery. Therefore, there is a risk that the battery may be in a use state that damages the secondary battery when the estimated accuracy of the battery state quantity is deteriorated.

  The present invention has been made to solve such problems, and an object of the present invention is to control a secondary battery that estimates a battery state quantity by parameter identification (learning control) based on sensor detection values. In the apparatus, the input / output possible electric energy is appropriately set when the estimated accuracy of the battery state quantity is deteriorated to prevent the secondary battery from being used in a severe state.

  The control apparatus for a secondary battery according to the present invention includes state quantity estimation means, determination means, and state quantity correction means. The state quantity estimating means sets the input / output possible electric energy of the secondary battery by identifying the control parameter of the secondary battery based on the detection value from the sensor provided in the secondary battery. The determination means determines the degree of control parameter identification. The state quantity correction means limits the input / output possible power amount to be smaller than the set value by the state quantity estimation unit according to the determination result by the determination means.

  According to the control apparatus for a secondary battery, it is possible to limit the amount of power that can be input / output to a value smaller than usual when the identification accuracy of the control parameter is lowered. Thereby, it is possible to reduce the risk of operating the secondary battery under harsh conditions during the period when there is a concern about the deterioration of the estimation accuracy of the battery state quantity, thereby preventing the battery life from decreasing.

  Preferably, in the control apparatus for a secondary battery according to the present invention, the state quantity correction means is from the generation of the control parameter learning reset instruction until the determination means determines that the degree of control parameter identification has reached a predetermined level or more. In the meantime, the amount of power that can be input and output is limited to a value set by the state quantity estimation unit.

  According to the control apparatus for a secondary battery, the input / output possible electric energy can be limited to be smaller than usual in the initial learning state immediately after the learning reset in which the deterioration of the control parameter identification accuracy is most concerned. Thereby, the danger of operating a secondary battery on severe conditions becomes low, and the fall of a battery life can be prevented.

  More preferably, the secondary battery control device according to the present invention further includes a restriction release control means. The restriction release means, after the control parameter learning reset instruction, when the determination means determines that the degree of control parameter identification has reached a predetermined level or more, the state quantity correction means limits the input / output possible power amount over time or Release gradually as the input / output current integration amount of the secondary battery increases.

  According to the secondary battery control device, it is possible to stably use the secondary battery by preventing the use state of the secondary battery from changing abruptly when the restriction on the input output possible electric energy is released.

  Alternatively, more preferably, the secondary battery is mounted on a vehicle including an electric motor that generates vehicle driving force and used as a power source for the electric motor.

  According to the secondary battery control device, the secondary battery mounted as an energy source for generating a vehicle driving force in a vehicle such as a hybrid vehicle or an electric vehicle has a limit performance and an amount of electric power that can be input / output in a normal state. In situations where there is a concern that the identification accuracy of control parameters may be lowered while being severely set to be pulled out, the secondary battery should be operated under harsh conditions by limiting the amount of input / output power to a value smaller than normal. Can be prevented. For this reason, a secondary battery can be used efficiently and safely under the situation where the amount of battery that can be mounted on a vehicle is limited.

  According to the control apparatus for a secondary battery of the present invention, it is possible to prevent the secondary battery from being used in a severe state by appropriately setting the input / output possible electric energy when the estimated accuracy of the battery state quantity is deteriorated.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following, the same or corresponding parts in the drawings are denoted by the same reference numerals, and the description thereof will not be repeated in principle.

  FIG. 1 is a schematic block diagram showing a configuration of a power supply system 5 to which a secondary battery control device according to an embodiment of the present invention is applied.

  Referring to FIG. 1, power supply system 5 includes a secondary battery 10, a load 20, relays 22 and 24, a control circuit 25, and a battery ECU 50. Battery ECU 50 corresponds to a control device for a secondary battery according to the embodiment of the present invention.

  The secondary battery 10 is typically composed of a plurality of cells configured to be rechargeable. In the embodiment of the present invention, the type of the secondary battery 10 is not particularly limited, and various secondary batteries such as a lead storage battery, a nickel hydride secondary battery, and a lithium ion battery can be applied.

  Load 20 includes a DC / DC converter 30, an inverter 40, and a motor generator 45.

  The DC / DC converter 30 converts the output voltage level of the secondary battery 10 and inputs it to the inverter 40. Inverter 40 converts the DC voltage output from DC / DC converter 30 into an AC voltage and supplies the AC voltage to motor generator 45. The output of the motor generator 45 can be transmitted to the drive wheels DWH via a transmission (not shown). In addition, the hybrid vehicle is equipped with an engine (not shown) that generates driving force by combustion of fuel such as gasoline, and the output of this engine can also be transmitted to the drive wheels DWH via a transmission (not shown). It can be configured.

  During regenerative braking operation of the vehicle, the motor generator 45 generates torque in the direction opposite to the rotation direction of the drive wheels DWH, so that the motor generator 45 performs regenerative power generation. Regenerative power generated by the motor generator 45 is converted into a DC voltage for charging the secondary battery 10 by the inverter 40 and the DC / DC converter 30. Regenerative braking of the vehicle means braking with regenerative power generation when the driver performs a foot brake operation, or braking deceleration (or regenerative power generation by turning off the accelerator pedal while driving without operating the foot brake) (or Stop acceleration).

  The relays 22 and 24 are connected between the secondary battery 10 and the load 20 to control power supply between them. ON / OFF of the relays 22 and 24 is controlled in response to a relay control signal SR from the control circuit 25. A power path between the secondary battery 10 and the load 20 is formed when the relays 22 and 24 are turned on, while a power meter supply path between the secondary battery 10 and the load 20 is cut off when the relays 22 and 24 are turned off. The As the relays 22 and 24, electromagnetic relays are typically applicable.

  The secondary battery 10 is provided with a temperature sensor 15, a voltage sensor 16, and a current sensor 18.

  The temperature sensor 15 is attached to a predetermined position of the secondary battery 10 and sends a voltage corresponding to the measured battery temperature BT to the battery ECU 50. The voltage sensor 16 is connected so as to be able to output the voltage between the terminals of the secondary battery 10 and / or the output voltage of each cell constituting the secondary battery 10, and the battery ECU 50 outputs a voltage corresponding to the measured battery voltage BV. To send. The current sensor 18 is arranged in the current input / output path of the secondary battery 10 and sends a voltage corresponding to the input / output current Bi of the secondary battery 10 to the battery ECU 50. Thereby, the battery ECU 50 can receive the battery temperature BT, the battery voltage BV, and the battery current Bi as sensor detection values.

  The battery ECU 50 estimates the internal state of the secondary battery 10 by learning the control parameter based on the sensor detection value, and the SOC that is the battery state amount, the input possible power value Pin that is the set value of the input / output power amount, and the output The possible power value Pout is calculated. These battery state quantities estimated by the battery ECU 50 are sent to the control circuit 25.

  The control circuit 25 considers the state quantities (SOC, Pin, Pout) of the secondary battery 10 estimated by the battery ECU 50 so that an operation command to the hybrid vehicle on which the power supply system 5 is mounted is achieved. Control instructions for the DC / DC converter 30 and the inverter 40 constituting the load 20 are generated in accordance with the output from the sensor appropriately disposed on the load 20. As a result, power is transferred between the secondary battery 10 and the load 20 within a range according to the input possible power value Pin and the output possible power value Pout.

  FIG. 2 is a functional block diagram for explaining internal state estimation of the secondary battery by the battery ECU 50 shown in FIG.

  Referring to FIG. 2, secondary battery internal state estimation system 100 includes a parameter identification unit 110, a state quantity estimation unit 120, an identification degree determination unit 130, a state quantity correction unit 140, and a limit switching unit 150. . The control operation by the secondary battery internal state estimation system 100 is realized by the battery ECU 50 executing a control calculation process according to a predetermined program.

  The parameter identification unit 110 receives the battery current Bi, the battery temperature BT, and the battery voltage BV that are sensor detection values by the sensors 15, 16, and 18 and identifies the control parameter Cpr of the secondary battery 10.

  The control parameter Cpr corresponds to physical circuit constants such as the open circuit voltage V0, the internal resistances R1 and R2, and the internal capacitance C1 that generates the polarization voltage in the equivalent circuit of the secondary battery 10 shown in FIG. 3, for example. Alternatively, a macro parameter (ΔBV / ΔBi, ΔSOC / ΔBi) such as a change amount of the SOC with respect to the battery current or an output voltage reflecting a change with time of these sensor detection values may be used as the control parameter Cpr. it can. Since these control parameters Cpr change from moment to moment according to changes in use state such as temperature changes, the secondary battery internal state estimation system 100 requires learning control by parameter identification.

  The control parameter identification can be performed based on any known method such as an adaptive digital filter or a Kalman filter. Also, there is no particular limitation on what variable is used as the control parameter.

  In response to input of sensor output values from the sensors 15, 16, and 18, the parameter identification unit 110 temporarily resets the control parameter identification and sets these control parameters to initial values when a learning reset instruction is input. The learning reset instruction is typically generated when the secondary battery 10 is replaced or removed for maintenance or when the operation of the battery ECU 50 is initialized due to power interruption of the battery ECU 50 or the like.

  The state quantity estimation unit 120 estimates the state quantity of the secondary battery 10 using the control parameter Cpr learned by the parameter identification unit 110. As described above, the state quantity of the secondary battery 10 estimated by the state quantity estimation unit 120 includes at least the SOC, the input possible power value Pin, and the output possible power value Pout.

  As described above, in a vehicle such as a hybrid vehicle, since the amount of battery that can be mounted on the vehicle is limited, it is required to draw out the limit performance of the secondary battery. For this reason, the setting of the input / output possible power values Pin and Pout by the state quantity estimation unit 120 is performed so as to draw out the limit performance of the secondary battery 10.

  The identification degree determination unit 130 sequentially monitors the control parameter Cpr identified by the parameter identification unit 110 and determines the degree of completion of control parameter identification. In particular, the identification degree determination unit 130 determines whether or not the identification degree of the control parameter has reached a predetermined level or more after the learning reset instruction is input and the initial learning state in which the identification accuracy of the control parameter has decreased due to the learning reset has been removed. This determination is made, for example, by (i) the elapsed time from the learning reset instruction input exceeding a predetermined value, or (ii) the integrated input / output current amount (| Bi |) to the secondary battery 10 after the learning reset instruction is input. Value) exceeds a predetermined value. Alternatively, (iii) the above determination can also be made based on whether or not the change amount of the control parameter Cpr per unit time or per unit input / output current integrated amount converges to a predetermined amount or a predetermined ratio or less. Further, the determination by the identification degree determination unit 130 may be performed by appropriately combining the determination conditions (i) to (iii). That is, the degree of identification evaluated by the degree-of-identification determination unit 130 is indicated by data (elapsed time, input / output current integrated amount, control parameter change amount, etc.) quantitatively indicating the above (i) to (iii).

  Restriction switching unit 150 selects one of paths P1 and P2 for outputting the state quantity estimated by state quantity estimation unit 120 to control circuit 25 according to the determination result of identification degree determination unit 130. The path P1 is selected in the initial learning state of the control parameter. When the route P1 is selected, the state quantity estimated by the state quantity estimation unit 120 is corrected by the state quantity correction unit 140 and then sent to the control circuit 25.

  The state quantity correction unit 140 adds a correction that limits at least the input / output power amount (Pin, Pout) among the state quantities estimated by the state quantity estimation unit 120.

  For example, as shown in the following equation (1), the input / output possible power values Pin # and Pout # estimated by the state quantity estimation unit 120 are set as predetermined limit coefficients. This is performed by decreasing the ratio according to k (0 <k <1.0).

Pin = Pin # · (1-k), Pout = Pout # · (1-k) (1)
Alternatively, the state quantity correction unit 140 may limit the input / output possible power amount according to the following equation (2) using the predetermined limit amounts ΔPin and ΔPout.

Pin = Pin # −ΔPin, Pout = Pout # −ΔPout (2)
Further, in the state quantity correction unit 140, the control parameter stores a fixed limit value (predetermined value) for the initial learning state, and is fixed instead of the input / output possible power calculated by the state quantity estimation unit 120. It is also possible to output the limited value to the control circuit 25.

  On the other hand, the path P2 is selected when the control parameter leaves the initial learning state (that is, in the normal learning state). When the route P2 is selected, the state quantity estimated by the state quantity estimation unit 120 without being passed through the state quantity correction unit 140 is output to the control circuit 25.

  FIG. 4 is a flowchart illustrating learning control including control parameters by the secondary battery control device according to the embodiment of the present invention.

  The flowchart of FIG. 4 corresponds to the control operation by the secondary battery internal state estimation system 100 shown in FIG.

  Referring to FIG. 4, battery ECU 50 determines in step S100 whether there is a learning reset instruction. When there is a learning reset instruction (when YES is determined in step S100), an initial identifying flag indicating that the control parameter Cpr is in the initial learning state is turned on in step S110. After the learning reset instruction is generated once, step S100 is NO and step S110 is skipped.

  In step S120, battery ECU 50 determines whether or not the initial identification flag is on. When the initial identification flag is on (when YES is determined in step S120) and the control parameter Cpr is in the initial learning state, input / output is possible so that the input / output power amount is limited in step S130. The power values Pin and Pout are corrected. This corresponds to the operation when the route P1 is selected in FIG. 2, and the processing in step S130 corresponds to the operation of the state quantity correction unit 140 in FIG.

  On the other hand, when the initial identification flag is off, that is, when the determination at step S120 is NO, the operation at the time of selecting the route P1 in FIG. The correction of the input / output possible power values Pin and Pout) is not performed.

  The control parameter identification by the parameter identification unit 110 in FIG. 2 is sequentially executed in step S140.

  Further, when the identification degree determination unit 130 determines that the initial learning state has left the initial learning state by the current identification processing in step S140 from the state where the initial identification flag is on, the battery ECU 50 determines YES in step S150. In this case, battery ECU 50 releases the restriction on the input / output possible electric energy in step S160. That is, the process in step S160 corresponds to an operation in which the limit switching unit in FIG. 2 switches the selection from the path P1 to the path P2.

  Further, in step S160, battery ECU 50 switches the initial identification flag from on to off. As a result, in the subsequent normal learning state of the control parameter Cpr, steps S120 and S160 are skipped, and the input / output possible power amount is not limited. That is, the input / output possible power values Pin and Pout estimated by the state quantity estimation unit 120 of FIG. 2 using the control parameter Cpr are employed.

  On the other hand, if the initial identification flag is on and the initial learning state has not been left even after the current identification processing in step S140, step S160 can be skipped. A quantity limit is valid.

  With such a configuration, it is possible to limit the amount of power that can be input / output to a value smaller than usual when the control parameter identification accuracy is reduced, which is represented in the initial learning state immediately after the learning reset. As a result, the risk of operating the secondary battery under harsh conditions is reduced during the period when there is a concern about the deterioration of the estimation accuracy of the battery state quantity, and the battery life can be prevented from decreasing.

  Note that the restriction cancellation of the input / output power (Pin, Pout) in step S160 of FIG. 4 can also be performed by the method shown in FIG.

  Referring to FIG. 5, when the initial identification flag is on (in the initial learning state), input / output possible power values Pin and Pout are set to predetermined limits by step S140 (that is, state quantity correction unit 140 in FIG. 2). It is in a state.

  Then, when the initial identification flag changes from on to off, the time from the initial transition of the initial identification flag to the off state is not used instead of immediately releasing the restriction on the input / output power amount and setting it to the “unlimited” state. The restriction state is gradually released as time passes or the integrated amount of input / output current increases. As indicated by the solid line, the restriction may be gradually released continuously as the elapsed time or the current integrated value increases, or the restriction may be released stepwise as indicated by the dotted line. . Such adjustment of the limit state is equivalent to, for example, gradually changing the limit coefficient k in equation (1) and the limit amounts ΔPin and ΔPout in equation (2). That is, the unrestricted state corresponds to the state of k = 0 in the equation (1) or ΔPin = ΔPout = 0 in the equation (2).

  As shown in FIG. 5, by using a configuration in which the restriction on the input / output possible electric energy is gradually released at the end of the initial learning state, it is possible to prevent the usage state of the secondary battery from changing abruptly.

  In order to perform the restriction release control of the input / output possible electric energy as shown in FIG. 5, when step S150 is determined as YES in the flowchart of FIG. 5 is a predetermined period or a period until the current integrated amount exceeds a predetermined value), it is necessary to adopt a control configuration that limits the input / output possible power values Pin and Pout according to FIG. In the block diagram of FIG. 2, the input / output as described above is inserted into the path P2 by inserting a restriction release unit (not shown) for limiting the amount of power that can be input / output as shown in FIG. The restriction release control of the possible electric energy becomes possible.

  In the present embodiment, the configuration in which the control parameters are identified and the battery state is estimated based on the sensor outputs from the current sensor, the voltage sensor, and the temperature sensor is illustrated for the secondary battery. However, the configuration further uses outputs from other sensors. Also good.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a schematic block diagram which shows the structure of the power supply system with which the control apparatus of the secondary battery according to embodiment of this invention is applied. FIG. 2 is a functional block diagram for explaining internal state estimation of a secondary battery by the battery ECU shown in FIG. 1. It is a circuit diagram which shows an example of the equivalent circuit of a secondary battery. It is a flowchart explaining the control parameter learning control in the control apparatus of the secondary battery according to the embodiment of the present invention. It is a figure explaining the variation of control operation at the time of cancellation of input-output electric power restriction.

Explanation of symbols

  5 Power system, 10 Secondary battery, 15 Temperature sensor, 16 Voltage sensor, 18 Current sensor, 20 Load, 22, 24 Relay, 25 Control circuit, 30 DC / DC converter, 40 Inverter, 45 Motor generator, 50 Battery ECU, 110 parameter identification unit, 120 state quantity estimation unit, 130 identification degree determination unit, 140 state quantity correction unit, 150 limit switching unit, Bi battery current (input / output current), BT battery temperature, BV battery voltage, C1 internal capacity (two Secondary battery), Cpr control parameter, DWH drive wheel, k I / O power limit factor, P1, P2 path, Pin input power, Pout output power, R1, R2 internal resistance (secondary battery), SR relay control signal , V0 open circuit voltage (secondary battery), ΔPin, ΔPout Noh power limit amount.

Claims (4)

A state quantity estimating means for setting an input / output possible electric energy of the secondary battery by identifying a control parameter of the secondary battery based on a detection value from a sensor provided in the secondary battery;
Determining means for determining the degree of identification of the control parameter;
A control apparatus for a secondary battery, comprising: a state quantity correction unit that limits the input / output possible power amount to be smaller than a set value by the state quantity estimation unit according to a determination result by the determination unit.   The state quantity correction means sets the input / output possible electric energy from the generation of the learning reset instruction of the control parameter until the determination means determines that the identification degree of the control parameter has reached a predetermined level or more. The control device for a secondary battery according to claim 1, wherein the control is limited more than a set value by the state quantity estimation unit.   After the instruction to reset the control parameter learning, when the determination unit determines that the identification degree of the control parameter has reached a predetermined level or more, the state quantity correction unit limits the input / output possible power amount over time. The secondary battery control device according to claim 2, further comprising restriction release control means for gradually releasing the input / output current integrated amount of the secondary battery according to an increase.   4. The secondary battery control device according to claim 1, wherein the secondary battery is mounted on a vehicle including an electric motor that generates a vehicle driving force and is used as a power source of the electric motor. 5.

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