JP2006033970A - Battery management system of hybrid vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery management system of hybrid vehicle capable of performing exact battery management by operating the discharge current of a battery from the power information of a load being connected with the battery and determining a current value with little noise component thereby eliminating the impact of current error due to the noise component. <P>SOLUTION: DC voltage of a battery is determined (S1) and then AC voltage phase and AC current phase on the inverter side are operated (S2, S3). AC power is operated using the AC side phase information (S4), power of the loads other than the inverter is operated (S5) and then DC current of the battery is operated from the power of the loads and the DC voltage (S6). Consequently, DC current of the battery can be determined as an operation value with little noise component and simplification of the system and cost reduction can be achieved by disusing a current sensor. Furthermore, high precision operation can be realized by calculating the residual capacity, available I/O power, and the like, using the operation value of DC current thereby eliminating the impact of current error. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a battery management system for a hybrid vehicle that manages a state of a battery that supplies electric power to a motor that generates traveling driving force via an inverter.

  In recent years, in vehicles such as automobiles, an engine that uses gasoline or other fuel as a power source is used with a motor that generates driving force by electric power from a battery for the purpose of promoting low pollution and resource saving. In addition, hybrid vehicles are being developed that use both an engine and a motor. In such a hybrid vehicle, it is important to accurately grasp and manage the battery state, and the remaining capacity is calculated using basic parameters such as battery voltage, current, and temperature.

For example, in Patent Document 1, based on the rate of change of the difference between the remaining capacity obtained by integrating the charge / discharge current of the battery measured by the current sensor and the remaining capacity estimated based on the open terminal voltage of the battery, A technique for correcting the calculation method of the remaining capacity is disclosed.
Japanese Patent Laid-Open No. 11-223665

  However, in a hybrid vehicle, since a load such as a motor or an inverter is connected, a current containing a large amount of harmonics flows, and when a battery current is measured by a current sensor, a value containing a lot of errors due to noise components is obtained. For this reason, as disclosed in Patent Document 1, if the remaining capacity is calculated by accumulating the battery current measured by the current sensor, there is a risk that an error may increase, which is a hindrance in performing accurate battery management. Become.

  The present invention has been made in view of the above circumstances, and calculates the current value with less noise component by calculating the charge / discharge current of the battery from the power information of the load connected to the battery, thereby eliminating the influence of the current error due to the noise component. It is an object of the present invention to provide a battery management system for a hybrid vehicle that can perform accurate battery management.

  In order to achieve the above object, a first battery management system for a hybrid vehicle according to the present invention is a battery management system for a hybrid vehicle that manages a state of a battery that supplies electric power to a motor that generates traveling driving force via an inverter. The load power calculation means for calculating the load power of the battery based on at least the power information of the inverter, the load power calculated by the load power calculation means and the DC voltage of the battery, DC current value calculating means for calculating the DC current value of the battery is provided.

  A second battery management system for a hybrid vehicle according to the present invention is a battery management device for a hybrid vehicle that manages a state of a battery that supplies electric power to a motor that generates traveling driving force via an inverter, and includes at least the inverter of the inverter. Based on the power information, a load power calculation means for calculating the load power of the battery, and a DC current value of the battery is calculated based on the load power calculated by the load power calculation means and the DC voltage of the battery. And a remaining capacity calculating means for calculating a remaining capacity of the battery using the current / current value calculated by the DC current value calculating means.

  At that time, the load power can be calculated based on information on the AC phase voltage, the AC phase current, and the phase in the inverter. The AC phase voltage can be calculated based on the rotational speed information of the motor. It is also possible to calculate using a value obtained by converting at least one of the AC phase voltage and the AC phase current into a DC amount on the magnetic flux axis and the torque axis in the motor vector control.

  In addition, the power information of the load other than the inverter can be calculated according to the operating state of the load. In the case of a converter that converts the DC voltage of the battery into a predetermined DC voltage, the load power of the converter is converted to the duty ratio of the switching operation. Can be calculated based on The load power other than the inverter is added to the load power based on the power information of the inverter as the load power of the battery.

  It is desirable to use at least one of a voltage measurement value on the inverter side and a voltage measurement value on the battery side as the DC voltage when calculating the DC current value from the load power of the battery.

  Further, when calculating the remaining capacity using the DC current value calculated from the load power of the battery, the first remaining capacity based on the integrated value of the estimated current value and the second remaining capacity based on the open circuit voltage of the battery Is preferably calculated by weighting and combining using weights set according to battery usage.

  The battery management system for a hybrid vehicle according to the present invention can calculate the charge / discharge current of the battery from the power information of the load connected to the battery to obtain a current value with a small noise component, and the influence of the current error due to the noise component can be obtained. Excluded accurate battery management can be performed.

  Embodiments of the present invention will be described below with reference to the drawings. 1 to 8 relate to an embodiment of the present invention, FIG. 1 is a configuration diagram showing a power system of a hybrid vehicle, FIG. 2 is a flowchart of DC current value calculation processing, and FIG. 3 is an estimation algorithm of a battery remaining capacity. FIG. 4 is an explanatory diagram of a weight table, FIG. 5 is an explanatory diagram of a current capacity table, FIG. 6 is a circuit diagram illustrating an equivalent circuit model, FIG. 7 is an explanatory diagram of an impedance table, and FIG. It is explanatory drawing.

  FIG. 1 shows a configuration of a power system of a hybrid (HEV) vehicle using both a motor and an engine. In FIG. 1, a motor 1 is a three-phase AC motor (for example, a permanent magnet type synchronous motor) driven by an inverter 2. ). The battery 3 that supplies power to the motor 1 via the inverter 2 is a high-voltage battery configured by connecting a plurality of battery packs in which a plurality of cells are sealed in series, for example.

  A battery controller 4 composed of a microcomputer or the like is connected to the battery 3, and the battery controller 4 and the inverter controller 5 that controls the inverter 2 communicate with each other via, for example, a CAN (Controller Area Network). Connected as possible. The battery 3 is connected to a DC-DC converter 6 that converts a high DC voltage from the battery 3 into a low voltage (for example, 12V) DC voltage. An auxiliary battery 7 for supplying power to various loads in the voltage system is connected.

  The battery controller 4 determines the battery status based on the remaining capacity indicated by the state of charge (SOC) of the battery 3, the input / output possible power amount indicated by the maximum input / output power in the battery 3, the degree of deterioration of the battery 3, etc. , The control of cooling and charging of the battery 3 after grasping the battery state, abnormality detection, protection operation at the time of abnormality detection, and the like are performed. Similarly, the inverter controller 5 is composed of a microcomputer or the like, and controls driving of the motor 1, regeneration control, and the like based on a command value, an accelerator opening signal, a brake signal, and the like from a control unit that controls the hybrid control system. Do.

  In the present embodiment, as described above, the battery controller 4 and the inverter controller 5 are connected so as to be capable of bidirectional communication with each other, and the function of the battery controller 4 and the function of the inverter controller 5 cooperate with each other. Is formed. In this battery management system, power information of the inverter 2 is transmitted from the inverter controller 5 to the battery controller 4, and a battery such as the remaining capacity of the battery 3, the input / output possible power amount, the deterioration state, etc. is transmitted from the battery controller 4 to the inverter controller 5. Data indicating the status is transmitted.

  In addition, since the DC-DC converter 6 is connected to the battery 3 as a load other than the inverter 2, in addition to the power information of the inverter 2, the power information of the DC-DC converter 6 is also input to the battery controller 4. Is done.

  In the battery controller 4, the voltage and temperature among the basic parameters representing the state of the battery 3, such as voltage, current, and temperature, are observed by a voltage sensor or a temperature sensor (not shown) disposed in the battery 3. However, the current, which is the most basic parameter for calculating the remaining capacity and the input / output possible power amount, is transmitted from the inverter controller 5 without providing a current sensor for detecting the current of the battery 3. The direct current value is calculated based on the power information and the power information of the DC-DC converter 6.

  That is, when various calculations are performed using the basic parameters of the battery 3 such as voltage, current, and temperature, the calculation accuracy depends on the measurement accuracy of each parameter. In particular, the battery current is compared with the terminal voltage and the battery temperature. The change due to charging / discharging is large, and the motor 1, inverter 2, DC-DC converter 6 and the like are connected. As a result, the current contains a lot of harmonics and there are many errors due to noise components. The error may increase.

  Therefore, the battery controller 4 obtains the DC current value in charging / discharging of the battery 3 as a calculation value with less noise component from the power information of the load represented by the inverter 2 without observing the battery current by the current sensor. ing. This simplifies the system configuration and reduces costs by eliminating the current sensor, and eliminates the effects of current errors by calculating the remaining capacity and input / output power using the calculated value of DC current. High-precision calculation.

  The calculation of the direct current in the battery controller 4 is a function as load power calculation means for calculating the load power of the battery 3 based on at least the power information of the inverter 2, and the direct current value based on the load power and direct current voltage of the battery 3. It is calculated by a function as a direct current value calculation means for calculating. Hereinafter, calculation of the direct current value based on the load power of the battery 3 will be described with reference to the flowchart of FIG.

  In this embodiment, an example in which the DC current value of the battery 3 is calculated on the battery controller 4 side will be described. However, the DC current value may be calculated on the inverter controller 5 side, and the DC current value data may be calculated. You may make it transmit to the battery controller 4. FIG.

First, in the battery 3, the electric power P indicated by the DC-side voltage Vdc and the current Idc is assumed to be the inverter 2 (and the motor 1) as a load of the battery 3 as shown in the following formula (1). 2 can be expressed as load power obtained by adding power information α by another load to power information based on the AC side phase voltage effective value Vac, phase current effective value Iac, and phase information θ.
P = Vdc × Idc = (Vac × Iac × cos θ × 3) / ηi + α (1)
Where ηi: Efficiency of inverter 2

  In the equation (1), the parameters required for the calculation of the remaining capacity and the like are the DC side voltage / current parameters Vdc and Idc. Therefore, in the DC current value calculation process shown in FIG. DC voltage Vdc, AC side phase voltage effective value Vac (and voltage phase), phase current effective value Iac (and current phase) are obtained, and AC side phase information θ is obtained in step S4 to calculate AC side power. To do. Then, in step S5, the power by the load other than the inverter is calculated, and in step S6, the AC side power is divided by the DC voltage Vdc to obtain the DC current Idc.

  Specifically, first, the value observed on either side of the battery controller 4 and the inverter controller 5 can be used as the DC-side voltage Vdc in step S1. When the observation value on the battery controller 4 side is used as the DC voltage Vdc, the total value of the voltages measured for each cell or the measurement value of the total voltage that becomes the terminal voltage of the entire battery 3 can be used.

  It is desirable to determine which voltage on the battery controller 4 side (battery 3 side) or inverter controller 5 side (inverter 2 side) is used as the DC voltage Vdc according to the capacity of the battery 3. In other words, when the capacity of the mounted battery is sufficiently large, the capacity of the mounted battery is measured using the voltage measurement value on the battery controller 4 side (practically, the sum of the voltage measurement values for each cell). Is relatively small and a large voltage fluctuation is expected, it is desirable to monitor the DC voltage on the inverter controller 5 side and provide voltage information to the battery controller 4, thereby ensuring the accuracy of the voltage. The hardware configuration can be simplified.

  Next, when the AC voltage is observed on the inverter 2 side, the measured value can be used as the AC voltage (phase voltage effective value) Vac in step S2, but the AC voltage is not observed. The calculation is performed based on the voltage information inside the inverter 2. For the calculation of the AC voltage, the method shown in (a) or (b) described below can be used.

(A) Use of voltage command value inside inverter Assuming that the motor 1 is controlled in vector, the AC voltage Vac is converted into a DC amount on the d-axis (magnetic flux axis) and the q-axis (torque axis). Using the voltage command value Vd on the d axis and the voltage voltage command value Vq on the q axis, the following equation (2) can be used. Here, the sign and coefficient may differ depending on the coordinate conversion of the vector control and the voltage equation definition method.
^{Vac = (Vd 2 + Vq 2} ) 1/2 / 3 1/2
= Vl / 3 ^1/2 (2)
Where Vl: AC line voltage effective value

At this time, the voltage command values Vd and Vq have a relationship as shown in the following equations (3) and (4) with the AC voltage Vac.
Vd = Vac × sin δ (3)
Vq = Vac × cos δ (4)

In the equations (3) and (4), δ is a voltage phase, and can be obtained by the following equation (5), for example.
δ = sin ⁻¹ (Vd / Vac) (5)

(B) Use of rotation speed information When the phase is fixed or the phase information can be detected, the AC voltage Vac can be obtained from the rotation speed information ω of the motor 1 as shown in the following equation (6). it can.
Vac = ω × Ke (6)
Where Ke: induced voltage constant

Next, the alternating current (phase current effective value) Iac in step S3 is obtained by calculation based on current information in the inverter. When performing vector control, the alternating current Iac can be obtained by the following equation (7) using the current command value Id on the d axis and the current command value Iq on the q axis.
Iac = (Id ² + Iq ² ) ^1/2 (7)

At this time, the current command values Id and Iq have a relationship as shown in the following equations (8) and (9) with the alternating current Iac.
Id = Iac × sin β (8)
Iq = Iac × cos β (9)

However, β in the equations (8) and (9) is a current phase, and can be obtained by the following equation (10), for example.
β = sin ⁻¹ (Id / Iac) (10)

  In the above, Id and Iq are command values, but they can also be calculated by feedback values. Further, when vector control is not performed, it is also possible to calculate the phase current effective value Iac from the captured three-phase alternating current.

Further, the phase information θ on the AC side in step S4 can be obtained by the following equation (11) using the voltage phase δ and the current phase β. Using this phase information θ, the inverter 2 in the equation (1) Side power (Vac × Iac × cos θ × 3) / ηi is obtained.
θ = (δ−β−γ) (11)
Where γ: correction term for voltage phase δ (correction from line voltage to phase voltage)

  In this case, the efficiency ηi of the inverter 2 may be assumed to be constant. However, an efficiency map using the load factor, the motor rotation speed, and the like as parameters is created in advance, and the efficiency is read from this map. Thus, the DC current Idc can be calculated with higher accuracy.

  Furthermore, in step S5, the power α of the load other than the inverter 2 (motor 1) is calculated as the load of the battery 3. As a load other than the inverter, for example, in the case of a load with a constant output, the power of the load can be easily known from information on the operation / non-operation of the device as the load. In the case of the DC-DC converter 6 The power of the DC-DC converter 6 can be estimated from the control duty information and the DC voltage. Then, the direct current Idc is obtained by dividing the power value obtained by adding the power α of another load such as the DC-DC converter 6 other than the inverter 2 to the alternating current power on the inverter 2 side by the direct current voltage Vdc in step S6. .

  As described above, by calculating the DC current value Idc using the information in the inverter 2, the current observed on the DC side (battery 3 side) is a discontinuous pulse at the time of low rotation and large torque (large current). In contrast to the current, it can be calculated as an averaged direct current. Then, by applying the calculated value of the direct current Idc to the calculation of the remaining capacity of the battery 3, the input / output possible power amount, and the like, it is possible to perform highly accurate calculation without the influence of the current error. Hereinafter, an example in which the DC current value Idc is applied to the calculation of the remaining capacity will be described.

  As is well known, the remaining capacity of the battery can be calculated based on the integrated value of the charge / discharge current and the open circuit voltage obtained from the impedance, but each has advantages and disadvantages. The former is resistant to load fluctuations such as an inrush current and provides a stable remaining capacity, but has a drawback that current errors are likely to accumulate (particularly, the errors increase when a high load is continued). In the latter case, an accurate value can be obtained in a region where the current is stable, but when the load fluctuates greatly in a short time, the impedance for estimating the open circuit voltage of the battery is obtained accurately. This is disadvantageous in that the calculated value of the remaining capacity tends to vibrate.

Therefore, the remaining capacity in this embodiment is the remaining capacity as the first remaining capacity obtained by integrating the current every predetermined time t according to the algorithm shown in FIG. 3 by the function as the remaining capacity calculating means in the battery controller 4. The capacity SOCI (t) and the remaining capacity SOCV (t) as the second remaining capacity obtained from the estimated value of the battery open voltage are calculated in parallel, and both are changed as needed according to the usage state of the battery 3. The final remaining capacity SOC (t) is calculated by weighting with weight (weight coefficient) w and combining. The weight w is changed between w = 0 and 1, and the final remaining capacity SOC (t) after synthesis is given by the following equation (12).
SOC (t) = w × SOCI (t) + (1−w) × SOCV (t) (12)

  The weight w needs to be determined using a parameter that can accurately represent the current battery usage. The parameters include the current change rate per unit time and the deviation between the remaining capacities SOCI and SOCV. Etc. can be used. The current change rate per unit time directly reflects the load fluctuation of the battery, but the mere current change rate is affected by a sudden change in current that occurs in a spike manner. Further, the current measurement value by the current sensor includes a lot of noise components, which becomes an error factor when calculating the rate of change by time differentiation of the current value.

  The spike-like current change can be prevented by using a current change rate that has undergone processing such as simple averaging, moving average, weighted averaging, etc., in particular, the charge / discharge state of the battery. The moving average that can appropriately reflect the past history without excessively functioning with respect to the change of the function functions as a low-pass filter that removes the spike component of the current without promoting the delay component. Further, since the DC current value Idc calculated from the load power information of the battery 3 has a smaller noise component than the current measurement value detected by the current sensor, the influence of the noise component can be suppressed.

  Therefore, by determining the weight w using the current change rate at the time t of the moving average value of the DC current value Idc, the spike component of the current generated by the load change during traveling is removed without promoting the delay component. At the same time, errors due to noise components can be suppressed. In this case, since the DC current value Idc having a small noise component calculated from the load power information of the battery 3 can be regarded as a value that has already been filtered, the DC current value Idc itself at the time t. The weight w may be determined using the current change rate. Hereinafter, the current change rate at the time t of the moving average value of the DC current value Idc and the current change rate at the time t of the DC current value Idc itself are described as ΔIdc / Δt as a representative.

  When the current change rate ΔIdc / Δt is large, the weight of the remaining capacity SOCI based on the current integration is increased, and the weight of the remaining capacity SOCV based on the open circuit voltage is decreased, so that the accurate remaining by the current integration can be achieved regardless of the load fluctuation. Capacitance can be obtained, and vibration during open circuit voltage estimation can be prevented. On the contrary, when the current change rate ΔIdc / Δt is small, the weight of the remaining capacity SOCI based on the current integration is reduced, and the weight of the remaining capacity SOCV based on the open circuit voltage is increased, thereby affecting the effect of error accumulation during current integration. And an accurate remaining capacity based on the open circuit voltage can be obtained.

  FIG. 4 shows an example of a weight table for determining the weight w, which is a one-dimensional table using the corrected current change rate KΔIdc / Δt obtained by correcting the temperature of the current change rate ΔIdc / Δt as a parameter. This weight table generally shows that the smaller the corrected current change rate KΔIdc / Δt, that is, the smaller the battery load fluctuation, the smaller the value of the weight w and the smaller the weight of the remaining capacity SOCI due to current integration. It has the characteristic to do.

  As a result, the accumulation of errors due to current integration is suppressed, and even when a disturbance occurs, a stable and accurate remaining capacity can be obtained, and the disadvantages of both the remaining capacity SOCI and SOCV can be canceled and mutual advantages can be obtained. It is possible to maximize the accuracy of estimation of the remaining capacity.

  Next, details of the calculation of the remaining capacity SOCI based on current integration and the remaining capacity SOCV based on the open circuit voltage will be described.

First, as shown in the following equation (13), the remaining capacity SOCI by current integration is obtained by integrating the current I every predetermined time using the remaining capacity SOC synthesized using the weight w as a base value.
SOCI (t) = SOC (t−1) −∫ [(100ηI / Ah) + SD] dt / 3600 (13)
Where η: current efficiency
Ah: Current capacity (variable depending on temperature)
SD: Self-discharge rate

  Although the current efficiency η and the self-discharge rate SD in the equation (13) can be regarded as constants (for example, η = 1, SD = 0), the current capacity Ah varies depending on the temperature. Therefore, when calculating the remaining capacity SOCI by this current integration, the current capacity Ah calculated by functionalizing the variation of the cell capacity with temperature is used.

  FIG. 5 shows an example of a current capacity table that stores a capacity ratio Ah ′ with respect to a rated capacity (for example, a rated current capacity when a predetermined number of cells are used as a reference unit) with the battery temperature T as a parameter. However, the current capacity decreases as the temperature becomes lower than the capacity ratio Ah ′ (= 1.00) at room temperature (25 ° C.), and therefore the value of the capacity ratio Ah ′ increases. Using the capacity ratio Ah ′ referred to from this current capacity table, the current capacity Ah at the temperature T for each measurement target can be calculated.

Further, the calculation of the remaining capacity SOCI (t) by the equation (13) is specifically executed by discrete time processing in the battery controller 4, and the combined remaining capacity SOC (t−1) one calculation cycle before is calculated as the current integration. (The delay operator Z ⁻¹ in the block diagram of FIG. 3). Therefore, errors do not accumulate or diverge, and even if the initial value is significantly different from the true value, it should converge to the true value after a predetermined time (for example, after several minutes). Can do.

  Furthermore, in the remaining capacity SOCI (t) according to the equation (13), conventionally, a measured value by a current sensor is used as the current I. However, the measured value by the current sensor has many noise components and errors are likely to accumulate. If the current sensor fails, the remaining capacity SOCI cannot be calculated. Therefore, by using the direct current value Idc with less noise component as the current I in the equation (13) instead of the measurement value by the current sensor, it is possible to reduce the accumulation of current errors and improve the calculation accuracy. Even when the current sensor fails, the calculation of the remaining capacity can be continued, and deterioration of controllability can be prevented.

On the other hand, in order to obtain the remaining capacity SOCV based on the estimation of the open circuit voltage, the estimated value of the open circuit voltage VOC is obtained from the battery terminal voltage V, the impedance Z, and the current I using the following equation (14).
VOC = V + I × Z (14)

  As the voltage V in the equation (14), the DC voltage Vdc used when calculating the DC current value Idc from the load power information of the battery 3, that is, the total value of the voltage measurement values for each cell observed on the battery controller 4 side. Either the measured value of the total voltage of the entire battery 3 or the DC voltage observed on the inverter controller 5 side can be used. As the current I, the DC current value Idc calculated from the load power information of the battery 3 is used.

  The impedance Z can be obtained using an impedance table created using the equivalent circuit model shown in FIG. The equivalent circuit of FIG. 6 is an equivalent circuit model in which the parameters of resistance components R1 to R3 and capacitance components C1, CPE1, and CPE2 (where CPE1 and CPE2 are double layer capacitance components) are combined in series and in parallel. Each parameter is determined by curve fitting a well-known Cole-Cole plot in the AC impedance method.

  The impedance Z obtained from these parameters varies greatly depending on the temperature of the battery, the electrochemical reaction rate, and the frequency component of the charge / discharge current. Therefore, the current change rate ΔIdc / Δt described above is employed as a frequency component replacement as a parameter for determining the impedance Z, impedance measurement is performed under the condition of the current change rate and the battery temperature, and data is accumulated. A table of impedance Z is created based on the rate of change and temperature.

  Specifically, since the internal impedance of the battery increases and the current change rate decreases as the temperature decreases, the impedance Z is determined directly using the corrected current change rate obtained by correcting the current change rate with temperature. To do. FIG. 7 shows an example of an impedance table in which impedance Z is stored using the above-described corrected current change rate KΔIdc / Δt based on the DC current value Idc and the temperature T measured by the temperature sensor as parameters. When the corrected current change rate KΔIdc / Δt is the same, the impedance Z increases as the temperature decreases, and at the same temperature, the impedance Z increases as the corrected current change rate KΔIdc / Δt decreases. Have a tendency to

  In the table shown in FIG. 7 and FIG. 8 described later, data in a range used under normal conditions is shown, and data in other ranges is omitted. Also, when using the moving average value of current per unit time as the current change rate, for example, when the calculation cycle of the DC current value Idc is 0.1 sec and the calculation cycle of current integration is 0.5 sec, A moving average value of 5 data is used.

After the open circuit voltage VOC is estimated, the remaining capacity SOCV is calculated based on the electrochemical relationship in the battery. Specifically, when the well-known Nernst equation describing the relationship between the electrode potential and the ion activity in the equilibrium state is applied and the relationship between the open circuit voltage VOC and the remaining capacity SOCV is expressed, the following (15) The formula can be obtained.
VOC = E + [(Rg × T / Ne × F) × lnSOCV / (100−SOCV)] + Y (15)
However, E: Standard electrode potential (for example, E = 3.745 in a lithium ion battery)
Rg: Gas constant (8.314 J / mol-K)
T: temperature (absolute temperature K)
Ne: Ion valence (Ne = 1 in the lithium ion battery of this embodiment)
F: Faraday constant (96485 C / mol)

Note that Y in the equation (15) is a correction term and expresses the voltage-SOC characteristic at normal temperature as a function of SOC. If SOCV = X, it can be expressed by a cubic function of SOC as shown in the following equation (16).
Y = −10 ⁻⁶ X ³ + 9 · 10 ⁻⁵ X ² + 0.013X−0.7311 (16)

  From the above equation (15), it can be seen that the remaining capacity SOCV has a strong correlation not only with the open circuit voltage VOC but also with the battery temperature. In this case, it is possible to directly calculate the remaining capacity SOCV using the equation (15) using the open circuit voltage VOC and the temperature T as parameters. Consideration of conditions is necessary.

  Therefore, when grasping the actual state of the battery from the relationship of the above equation (15), a charge / discharge test or simulation in each temperature range is performed based on the SOCV-VOC characteristics at room temperature, and the actual measurement data is obtained. accumulate. Then, a table of the remaining capacity SOCV is created from the accumulated measured data and the open circuit voltage VOC and temperature T are parameters, and the remaining capacity SOCV is obtained using this table.

  FIG. 8 shows an example of the remaining capacity table. Generally, the lower the temperature T and the open circuit voltage VOC, the smaller the remaining capacity SOCV, and the higher the temperature T and the open circuit voltage VOC, the remaining capacity. The capacity SOCV tends to increase.

  Then, after calculating the remaining capacities SOCI and SOCV, the remaining capacities SOCI and SOCV are weighted and synthesized using the weight w as shown in the above equation (12) to calculate the remaining capacities SOC.

  As described above, in the present embodiment, by using the load power information of the battery 3, it is possible to calculate the DC current value Idc with less noise component compared to the current value measured by the current sensor. By using the DC current value Idc, it is possible to improve the calculation accuracy of the remaining capacity and the like, and it is possible to always perform accurate battery management.

Configuration diagram showing the power system of a hybrid vehicle Flow chart of DC current value calculation processing Block diagram showing the remaining battery capacity estimation algorithm Illustration of weight table Illustration of current capacity table Circuit diagram showing equivalent circuit model Illustration of impedance table Explanation of remaining capacity table

Explanation of symbols

1 motor 2 inverter 3 battery 4 battery controller (load power calculation means, DC current value calculation means, remaining capacity calculation means)
5 Inverter controller 6 DC-DC converter P Load power Idc DC current Vdc DC voltage Vac Phase voltage effective value Iac Phase current effective value θ Phase information SOCI remaining capacity (first remaining capacity)
SOCV remaining capacity (second remaining capacity)
SOC remaining capacity w weight
Agent Patent Attorney Susumu Ito

Claims (9)

A battery management system for a hybrid vehicle that manages a state of a battery that supplies electric power to a motor that generates a driving force via an inverter,
Load power calculating means for calculating the load power of the battery based on at least the power information of the inverter;
A battery management for a hybrid vehicle, comprising: DC current value calculation means for calculating a DC current value of the battery based on the load power calculated by the load power calculation means and the DC voltage of the battery. system. A battery management device for a hybrid vehicle that manages a state of a battery that supplies electric power to a motor that generates a driving force via an inverter,
Load power calculating means for calculating the load power of the battery based on at least the power information of the inverter;
DC current value calculating means for calculating a DC current value of the battery based on the load power calculated by the load power calculating means and a DC voltage of the battery;
A battery management system for a hybrid vehicle, comprising: a remaining capacity calculation means for calculating a remaining capacity of the battery using the current / current value calculated by the DC current value calculation means. The load power calculation means includes
3. The hybrid vehicle battery management system according to claim 1, wherein the load power is calculated based on information on an AC phase voltage, an AC phase current, and a phase in the inverter. 4. The load power calculation means includes
4. The hybrid vehicle battery management system according to claim 3, wherein the AC phase voltage is calculated based on rotation speed information of the motor. The load power calculation means includes
5. The calculation according to claim 3, wherein at least one of the AC phase voltage and the AC phase current is calculated using a value obtained by converting the DC amount on the magnetic flux axis and the torque axis in the vector control of the motor. Hybrid vehicle battery management system. The load power calculation means includes
The power information of a load other than the inverter is calculated according to the operating state of the load, and is added to the load power based on the power information of the inverter as the load power of the battery. A battery management system for a hybrid vehicle as described in 1. The load power calculation means includes
When the load other than the inverter is a converter that converts the DC voltage of the battery into a predetermined DC voltage, the load power of the converter is calculated based on the duty ratio of the switching operation, and the load power of the battery is calculated as the load power of the battery. The battery management system for a hybrid vehicle according to claim 6, wherein the battery power management system adds the load power based on the power information. The DC current value calculation means includes:
8. The hybrid vehicle according to claim 1, wherein at least one of a voltage measurement value on the inverter side and a voltage measurement value on the battery side is used as the DC voltage of the battery. Battery management system. The remaining capacity calculation means is:
The first remaining capacity based on the integrated value of the DC current value and the second remaining capacity based on the open circuit voltage of the battery are weighted and synthesized using a weight set according to the use state of the battery, and the battery The battery management system for a hybrid vehicle according to any one of claims 2 to 8, wherein the remaining capacity is calculated.

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