JP2017225211A - Capacitor controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a capacitor controller that is able to protect deterioration of each of capacitors even if there is difference between the capacitors.SOLUTION: A capacitor controller comprises: a plurality of capacitors connected in parallel; a state acquiring section that acquires a state of each capacitor; and a control section that controls output of each of the plurality of capacitors on the basis of information acquired by the state acquiring section. On the basis of information acquired by the state acquiring section, the control section derives a permissible current value and target current value for each capacitor, and exerts control such that each capacitor outputs a current corresponding to the permissible current value and target current value of each capacitor.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a capacitor control device that controls the outputs of a plurality of capacitors connected in parallel.

  In Patent Document 1, the output permitted power of each power storage device is set based on the remaining capacity of two power storage devices connected in parallel, and the permitted power output from the entire two power storage devices is set between the two power storage devices. An electric vehicle including a control device that sets a value that doubles the minimum value of output permission power is described.

JP2013-183524A

  FIG. 6 shows the output power of the entire two power storage devices when the internal resistance changes and bias occurs between the power storage devices based on the technology described in Patent Document 1 described above. And it is a graph which shows an example of each time-dependent change of the electric current and voltage of each electrical storage apparatus. In the example shown in FIG. 6, as shown in FIG. 7, the output permission power of the first power storage device having an internal resistance of 9 mΩ is 10 kW, and the output permission power of the second power storage device having an internal resistance of 9 mΩ is 20 kW. It is a graph in a state where the internal resistance of the first power storage device is changed from 9 (= 3 + 3 + 3) mΩ to 7 (= 1 + 5 + 1) mΩ. Since the output permission power of the first power storage device is 10 kW and the output permission power of the second power storage device is 20 kW, the control device of Patent Document 1 uses the permitted power (total permission power) output from the entire two power storage devices. A value obtained by doubling 10 kW (= 20 kW) is set. As a result, 11.25 (= 20 × {9 / (7 + 9)}) kW of power is output from the first power storage device, and 8.75 (= 20 × {7 / (7 + 9)) from the second power storage device. }) KW power is output.

  Since the output permission power of the second power storage device is 20 kW, there is no problem in outputting 8.75 kW power, but when the first power storage device with output permission power of 10 kW outputs 11.25 kW power, 1 The deterioration of the power storage device is promoted. That is, as shown in FIG. 6, since the actual current of the first power storage device exceeds the permitted current according to the output permitted power of 10 kW, the minimum cell voltage of the first power storage device is the lower limit value of the voltage range in which deterioration does not accelerate It is below the limit value. As described above, when resistance variation or the like occurs in a part of the plurality of power storage devices connected in parallel and deviation occurs between the power storage devices, the technology described in Patent Document 1 cannot protect the power storage device from deterioration. was there.

  An object of the present invention is to provide a capacitor control device that can protect against deterioration of a capacitor even if there is a bias between the capacitors.

In order to achieve the above object, the invention described in claim 1
A plurality of power storage devices connected in parallel (for example, power storage cells C11 to C1n of the first power storage device ES1 and power storage cells C21 to C2n of the second power storage device ES2 in embodiments described later),
A state acquisition unit (for example, voltage sensors SV11 to SV1n, SV21 to SV2n, current sensors SI1 and SI2 in embodiments described later) for acquiring the state of each capacitor;
A control unit (e.g., an ECU 109 in an embodiment described later) that controls the outputs of the plurality of capacitors based on the information acquired by the state acquisition unit,
The control unit derives a permitted current value and a target current value for each capacitor based on the information acquired by the state acquisition unit, and a current having a value corresponding to the permitted current value and the target current value for each capacitor. Is a capacitor control device that controls the output power of the plurality of capacitors as a whole.

The invention according to claim 2 is the invention according to claim 1,
The control unit determines output permission power of each capacitor so that each capacitor outputs a current equal to or smaller than the smaller one of the permitted current value and the target current value for each capacitor.

In the invention according to claim 3, in the invention according to claim 1 or 2,
The plurality of capacitors include two capacitors,
The control unit is configured based on a coefficient indicating the characteristic deviation between the two capacitors obtained from the first information indicating the state of one capacitor and the second information indicating the state of the other capacitor. The target current value of the battery is derived.

The invention according to claim 4 is the invention according to claim 3,
The first information and the second information are information indicating a current flowing through the capacitor or an internal resistance of the capacitor.

The invention according to claim 5 is the invention according to claim 4,
The controller is
If the absolute value of each current flowing through the two capacitors is greater than or equal to a predetermined value, the target current of each capacitor based on the coefficient obtained from the first information and the second information indicating the current flowing through the capacitor Derive the value,
If the absolute value of each current flowing through the two capacitors is less than the predetermined value, the target of each capacitor is based on the coefficient obtained from the first information and the second information indicating the internal resistance of the capacitor. The current value is derived.

The invention according to claim 6 is the invention according to claim 4,
The controller is
The larger the amount of change per unit time of the absolute value of each current flowing through the two capacitors, the larger the weighting coefficient, the first information and the second information indicating the current flowing through the capacitor, and the Based on the coefficient obtained from the first information and the second information indicating the internal resistance, the target current value of each capacitor is derived.

  According to the first aspect of the present invention, even if there is a bias in characteristics among a plurality of capacitors connected in parallel, based on the permitted current value and the target current value for each capacitor, a current corresponding to the bias is supplied to each capacitor. To control the output power of the entire plurality of capacitors. As a result, each capacitor does not perform output that promotes deterioration. Thus, even if there is a bias in characteristics between the capacitors, protection against deterioration of the capacitors can be performed.

  According to the second aspect of the present invention, since the output permission power of each capacitor is determined so as to output the minimum current between the permitted current value and the target current value for each capacitor, the output voltage of each capacitor has a lower limit value. Not below. Since it is desirable to use a capacitor within a voltage range in which deterioration does not accelerate, it is possible to protect the capacitor against deterioration by controlling the output voltage of each capacitor so as to be within the voltage range.

  According to the invention of claim 3, the target current value of each capacitor is derived based on the characteristic deviation between the two capacitors. For this reason, the output of each capacitor can be controlled so as not to promote deterioration based on an appropriate target current value and allowable current value corresponding to the degree of bias.

  According to the invention of claim 4, the characteristic deviation between the two capacitors is set by the current flowing through the capacitor or the internal resistance of the capacitor. Therefore, when either current variation or internal resistance variation occurs between the two capacitors, it is possible to protect against degradation of the capacitor.

  According to the invention of claim 5, if the absolute value of each current flowing through two capacitors is greater than or equal to a predetermined value, the characteristic bias between the two capacitors is set by the current, and if less than the predetermined value, the bias Is set by the internal resistance. For this reason, even when the magnitude of the current variation is smaller than the sensor error, the coefficient indicating the bias is represented by the internal resistance, so that the target current value of each capacitor can be derived appropriately. As a result, it is possible to protect against deterioration of the battery.

  According to the invention of claim 6, the characteristic between the two capacitors from the first information and the second information using the weighting coefficient according to the amount of change per unit time of the absolute value of each current flowing through the two capacitors. By calculating a coefficient indicating the deviation of the current, a precise drift coefficient K can be calculated.

It is a figure which shows the circuit structure of the drive system which the electric vehicle of one Embodiment has. It is a block diagram which shows the internal structure which concerns on the 1st function part of ECU. It is a block diagram which shows the internal structure which concerns on the 1st function part of ECU. The output power of the battery pack, the current and voltage of each power storage device when the internal resistance of the power storage cell changes in the first power storage device and a characteristic bias occurs between the first power storage device and the second power storage device, And it is a graph which shows an example of each time-dependent change of a drift coefficient. It is a figure which shows the state by which the bias | inclination of the characteristic generate | occur | produced between the electrical storage apparatuses because internal resistance changed in the 1st electrical storage apparatus. Based on the technology described in Patent Literature 1, when the internal resistance changes in one of the two power storage devices and a bias occurs between the power storage devices, the output power of the entire two power storage devices and the current of each power storage device It is a graph which shows an example of each time-dependent change of voltage. It is a figure which shows the relationship between the output electric power of each electrical storage apparatus, and each output permission electric power when internal resistance changes in one of two electrical storage apparatuses.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram illustrating a circuit configuration of a drive system included in an electric vehicle according to an embodiment. A 1MOT type electric vehicle shown in FIG. 1 includes a motor generator (MG) 101, a battery pack 103, a VCU (Voltage Control Unit) 105, a PDU (Power Drive Unit) 107, an ECU (Electronic Control Unit) 109, Is provided.

  The motor generator 101 is driven by electric power obtained from the battery pack 103 to generate power for the electric vehicle to travel.

  The battery pack 103 is configured by connecting a first power storage device ES1 and a second power storage device ES2 in parallel. The first power storage device ES1 includes a plurality of power storage cells C11 to C1n connected in series such as a lithium ion battery or a nickel metal hydride battery, and a voltage for detecting an OCV (open circuit voltage) or a terminal voltage that is a cell voltage of each power storage cell. Sensors SV11 to SV1n and a current sensor SI1 that detects an input / output current I1 of the first power storage device ES1. The second power storage device ES2 detects a plurality of power storage cells C21 to C2n connected in series such as a lithium ion battery or a nickel metal hydride battery, and an OCV (open circuit voltage) or terminal voltage that is a cell voltage of each power storage cell. Voltage sensors SV21 to SV2n, and a current sensor SI2 that detects an input / output current I2 of the second power storage device ES2. Each signal indicating the voltage detected by the voltage sensors SV11 to SV1n and the voltage sensors SV21 to SV2n is sent to the ECU 109. A signal indicating the current I1 detected by the current sensor SI1 and a signal indicating the current I2 detected by the current sensor SI2 are also sent to the ECU 109.

  Note that the deterioration coefficient indicating the deterioration resistance of the storage cell in charging / discharging of the first power storage device ES1 or the second power storage device ES2 is a voltage in a state where the charge rate (SOC) is high to a state where the charge rate is low. In this range, the degradation coefficient is large when a voltage outside the range is output. Therefore, a voltage range in which the deterioration coefficient is equal to or less than a predetermined value is set as a suitable region in each power storage device.

  The VCU 105 boosts and outputs the voltage of the battery pack 103 by switching on and off the plurality of switching elements using the voltage of the battery pack 103 as an input voltage. Note that the ECU 109 controls the voltage level or current level of the DC power output from the VCU 105.

  PDU 107 converts a DC voltage into an AC voltage by switching on and off a plurality of switching elements, and supplies a three-phase current to motor generator 101.

  The ECU 109 includes a first function unit that determines the permitted power of the battery pack 103 and a second function unit that controls the VCU 105 and the PDU 107 based on the permitted power determined by the first function unit. 2 and 3 are block diagrams showing the internal configuration of the first functional unit of the ECU 109. As shown in FIG. As shown in FIGS. 2 and 3, the first functional unit of the ECU 109 includes internal resistance calculation units 111 and 112, a first permitted current calculation unit 131, a second permitted current calculation unit 132, and a drift coefficient calculation unit 150. A first target current calculation unit 171, a second target current calculation unit 172, a first branch current maximum value setting unit 191, a second branch current maximum value setting unit 192, and a first permitted power calculation unit 201. The second permitted power calculation unit 202 and the battery pack permitted power setting unit 211 are included.

The internal resistance calculation unit 111 includes the amount of change (dV1i) of each terminal voltage V11... V1n detected by the voltage sensors SV11 to SV1n of the first power storage device ES1 and the current I1 detected by the current sensor SI1 of the first power storage device ES1. Based on the change amount (dI1), the internal resistances R11... R1n of the power storage cells C11 to C1n included in the first power storage device ES1 are calculated from the following formula (1).
R1i = dV1i / dI1 (1)
(I = 1 to n)

The internal resistance calculation unit 112 calculates the amount of change (dV2i) of each terminal voltage V21 ... V2n detected by the voltage sensors SV21 to SV2n of the second power storage device ES2 and the current I2 detected by the current sensor SI2 of the second power storage device ES2. Based on the amount of change (dI2), the internal resistances R21... R2n of the power storage cells C21 to C2n included in the second power storage device ES2 are calculated from the following formula (2).
R2i = dV2i / dI2 (2)
(I = 1 to n)

The first allowed current calculation unit 131 includes the OCV11... OCV1n detected by the voltage sensors SV11 to SV1n of the first power storage device ES1, the limit value Vlim, and the power storage included in the first power storage device ES1 calculated by the internal resistance calculation unit 111. Based on the internal resistances R11... R1n of the cells C11 to C1n, the permission current Ilim1 for the first branch current I1 of the first power storage device ES1 is calculated from the following equation (3). The limit value Vlim is a voltage lower limit value in a suitable region where the deterioration coefficient is equal to or less than a predetermined value in the first power storage device ES1.

The second permitted current calculation unit 132 includes the OCV21... OCV2n detected by the voltage sensors SV21 to SV2n of the second power storage device ES2, the limit value Vlim, and the power storage included in the second power storage device ES2 calculated by the internal resistance calculation unit 112. Based on the internal resistances R21... R2n of the cells C21 to C2n, the permission current Ilim2 for the second branch current I2 of the second power storage device ES2 is calculated from the following equation (4). The limit value Vlim is a voltage lower limit value in a suitable region where the deterioration coefficient is equal to or less than a predetermined value in the second power storage device ES2.

The drift coefficient calculation unit 150 includes the current I1 detected by the current sensor SI1 of the first power storage device ES1 and the current I2 detected by the current sensor SI2 of the second power storage device ES2, or the internal resistance R11 calculated by the internal resistance calculation unit 111. ... based on the total value ΣR1i of R1n and the total value ΣR2i of the internal resistances R21 ... R2n calculated by the internal resistance calculation unit 112, from the following formula (5), the characteristics between the first power storage device ES1 and the second power storage device ES2 A drift coefficient K indicating the degree of bias is calculated. Note that the characteristic bias between the first power storage device ES1 and the second power storage device ES2 is caused by a change in internal resistance in at least one of the power storage devices.
K = I2 / I1 or ΣR1i / ΣR2i (5)
(I = 1 to n)

  If the absolute value of each value of the current I1 and the current I2 is larger than the error that can be included in the detection values of the current sensors SI1 and SI2, the drift coefficient calculation unit 150 calculates from the equation “K = I2 / I1”. The drift coefficient K is calculated, and if the absolute value of at least one of the currents I1 and I2 is smaller than the error, the drift coefficient K is calculated from the equation “K = ΣR1i / ΣR2i”.

  In addition, the drift coefficient calculation unit 150 uses two weights “I2 / I1” and “ΣR1i / ΣR2i” that are weighted differently according to the amount of change per unit time of at least one absolute value of the current I1 and the current I2. The drift coefficient K may be calculated. That is, when the weighting coefficient is “h (0 ≦ h ≦ 1)” and the calculation formula of K = hΣR1i / ΣR2i + (1-h) I2 / I1 is used, the drift coefficient calculation unit 150 calculates the current I1 and the current The weighting coefficient h is set to a value closer to 1 as the amount of change per unit time of at least one absolute value of I2 increases.

The first target current calculation unit 171 calculates the first power storage from the following equation (6) based on the permission current Ilim2 calculated by the second permission current calculation unit 132 and the drift coefficient K calculated by the drift coefficient calculation unit 150. A target current Itar1 for the first branch current I1 of the device ES1 is calculated. The target current Itar1 is a current value set in order to keep the second branch current I2 of the second power storage device ES2 within the permitted current Ilim2.
Itar1 = Ilim2 × 1 / K (6)

The second target current calculation unit 172 calculates the second power storage from the following equation (7) based on the permission current Ilim1 calculated by the first permission current calculation unit 131 and the drift coefficient K calculated by the drift coefficient calculation unit 150. A target current Itar2 for the second branch current I2 of the device ES2 is calculated. The target current Itar2 is a current value set in order to keep the first branch current I1 of the first power storage device ES1 within the permitted current Ilim1.
Itar2 = Ilim1 × K (7)

  The first tributary current maximum value setting unit 191 includes a permission current Ilim1 calculated by the first permission current calculation unit 131 and a first target current calculation unit 171 for the maximum value I1max of the first branch current I1 of the first power storage device ES1. A smaller current value of the calculated target current Itar1 is set. In addition, the second branch current maximum value setting unit 192 includes the permitted current Ilim2 calculated by the second permitted current calculation unit 132 and the second target current calculation unit for the maximum value I2max of the second branch current I2 of the second power storage device ES2. 172 is set to the smaller current value of the target current Itar2 calculated.

  The first allowed power calculation unit 201 calculates voltage sensors SV11 to SV1 from values (voltages) obtained by multiplying the maximum value I1max of the first branch current I1 and the total value ΣR1i of the internal resistances of the battery cells of the first power storage device ES1. A value (power) obtained by multiplying a value ΔV1 obtained by subtracting the total value ΣOCV1i of each OCV11... OCV1n detected by SV1n by the maximum value I1max of the first tributary current I1 is calculated as output permission power of the first power storage device ES1.

  The second allowed power calculation unit 202 calculates the voltage sensor SV21 to the value (voltage) obtained by multiplying the maximum value I2max of the second branch current I2 by the total value ΣR2i of the internal resistances of the battery cells of the second power storage device ES2. A value (power) obtained by multiplying the value ΔV2 obtained by subtracting the total value ΣOCV2i of each OCV21... OCV2n detected by SV2n by the maximum value I2max of the second branch current I2 is calculated as the output permission power of the second power storage device ES2.

  The battery pack permitted power setting unit 211 uses the output permitted power of the second power storage device ES2 calculated by the second permitted power calculation unit 202 to the output permitted power of the first power storage device ES1 calculated by the first permitted power calculation unit 201. The added value is set as the output permission power of the battery pack 103 (hereinafter referred to as “battery pack permission power”). The second functional unit of the ECU 109 performs switching control of the VCU 105 and the PDU 107 so that the output power of the battery pack 103 is equal to or lower than the battery pack permission power.

  FIG. 4 shows the output power of the battery pack 103 when the internal resistance of the power storage cell changes in the first power storage device ES1 and a characteristic bias occurs between the first power storage device ES1 and the second power storage device ES2. It is a graph which shows an example of each time-dependent change of the electric current and voltage of each electrical storage apparatus, and the drift coefficient K. In the example shown in FIG. 4, as shown in FIG. 5, the first power storage device ES1 and the second power storage device ES2 are configured by connecting three power storage cells each having an internal resistance of 3 mΩ in series. The output permission power of ES1 is set to 10 kW, the output permission power of the second power storage device ES2 is set to 20 kW, and the internal resistance of the first power storage device ES1 is changed from 9 (= 3 + 3 + 3) mΩ to 7 (= 1 + 5 + 1) mΩ. As a result, a case is shown in which a bias in characteristics occurs between the first power storage device ES1 and the second power storage device ES2. Due to the change in the internal resistance, the allowed current Ilim1 of the first power storage device ES1 is decreased, and the drift coefficient K is changed from 1 to about 0.8 (= 7/9). As a result, the target current Itar2 (= Ilim1 × K) of the second power storage device ES2 decreases, and the target current Itar1 (= Ilim2 × 1 / K) of the first power storage device ES1 increases.

  The first branch current I1 of the first power storage device ES1 is controlled to be equal to or smaller than the smaller one of the permitted current Ilim1 and the target current Itar1. In the example shown in FIG. 4, the target current Itar1 increases, but the permission current Ilim1 decreases. Therefore, the first branch current I1 of the first power storage device ES1 is controlled so that the permission current Ilim1 becomes the upper limit. Further, the second branch current I2 of the second power storage device ES2 is controlled to be equal to or smaller than the smaller one of the permission current Ilim2 and the target current Itar2. In the example illustrated in FIG. 4, the permission current Ilim2 is not changed, but the target current Itar2 is decreased. Therefore, the second branch current I2 of the second power storage device ES2 is controlled so that the target current Itar2 becomes the upper limit.

  As described above, even if a characteristic deviation occurs between the power storage devices due to a change in internal resistance or the like, a target current based on the drift coefficient K is set for each power storage device, and either the target current or the permitted current is smaller. The current flowing through each power storage device is controlled so that the upper limit is the upper limit, and an increase in current due to bias is suppressed. As a result, as shown in FIG. 4, since the minimum cell voltage of either power storage device does not fall below the limit value Vlim, the power storage cell of the power storage device can be protected from deterioration.

  As described above, according to the present embodiment, even if there is a bias in characteristics among a plurality of power storage devices connected in parallel, a value corresponding to the bias is obtained based on the permitted current and the target current for each power storage device. The battery pack permission power is set so that current flows through each power storage device. At this time, each power storage device is controlled to output a current having an upper limit of the minimum value of the permitted current and the target current for each power storage device, so the minimum cell voltage of each power storage device does not fall below the lower limit value. Since it is desirable to use the power storage device in a voltage range in which deterioration does not promote, each power storage device outputs an output that promotes deterioration by controlling the output voltage of the power storage cell of each power storage device so as to be within the voltage range. Not performed. Therefore, even if there is a bias in characteristics between the power storage devices, protection against deterioration of the power storage devices can be performed.

  The drift coefficient K used to calculate the target current is the current if the absolute value of each current flowing through the two power storage devices is larger than an error that can be included in the detection values of the current sensors SI1 and SI2. If the value is smaller than the above error, it is calculated by the ratio of the internal resistance. For this reason, even if the magnitude of current variation is smaller than the sensor error, the drift coefficient K indicating the bias is represented by the internal resistance, so that the target current of each power storage device can be derived appropriately. Also, by using the weighting coefficient according to the amount of change per unit time of the absolute value of each current flowing through the two power storage devices, the drift coefficient K is calculated from the ratio of the current and the ratio of the internal resistance, thereby providing high accuracy. The drift coefficient K can be calculated.

  In addition, this invention is not limited to embodiment mentioned above, A deformation | transformation, improvement, etc. are possible suitably. For example, the power storage cells included in each of the first power storage device ES1 and the second power storage device ES2 are not limited to the secondary battery such as the above-described lithium ion battery or nickel hydride battery. For example, a capacitor or a capacitor that has a small storage capacity but can charge and discharge a large amount of power in a short time may be used as the storage cell.

101 Motor generator 103 Battery pack 105 VCU
107 PDU
109 ECU
111, 112 Internal resistance calculation unit 131 First permission current calculation unit 132 Second permission current calculation unit 150 Drift coefficient calculation unit 171 First target current calculation unit 172 Second target current calculation unit 191 First branch current maximum value setting unit 192 Second branch current maximum value setting unit 201 First permitted power calculation unit 202 Second permitted power calculation unit 211 Battery pack permitted power setting unit ES1 First power storage device ES2 Second power storage device

Claims (6)

A plurality of capacitors connected in parallel;
A state acquisition unit for acquiring the state of each capacitor;
A control unit that controls the outputs of the plurality of capacitors based on the information acquired by the state acquisition unit;
The control unit derives a permitted current value and a target current value for each capacitor based on the information acquired by the state acquisition unit, and a current having a value corresponding to the permitted current value and the target current value for each capacitor. Is a capacitor control device that controls output power of the plurality of capacitors as a whole. The capacitor control device according to claim 1,
The said control part is an electrical storage device control apparatus which determines the output permission electric power of each electrical storage device so that each electrical storage device outputs the electric current below the value of the said permission electric current value and the said target electric current value for every said electrical storage device. It is a capacitor | condenser control apparatus of Claim 1 or 2, Comprising:
The plurality of capacitors include two capacitors,
The control unit is configured based on a coefficient indicating the characteristic deviation between the two capacitors obtained from the first information indicating the state of one capacitor and the second information indicating the state of the other capacitor. A capacitor control device for deriving the target current value of the capacitor. The capacitor control device according to claim 3,
The storage device control apparatus, wherein the first information and the second information are information indicating a current flowing through the storage device or an internal resistance of the storage device. The capacitor control device according to claim 4,
The controller is
If the absolute value of each current flowing through the two capacitors is greater than or equal to a predetermined value, the target current of each capacitor based on the coefficient obtained from the first information and the second information indicating the current flowing through the capacitor Derive the value,
If the absolute value of each current flowing through the two capacitors is less than the predetermined value, the target of each capacitor is based on the coefficient obtained from the first information and the second information indicating the internal resistance of the capacitor. A capacitor control device for deriving a current value. The capacitor control device according to claim 4,
The controller is
A weighting factor that varies depending on a change amount per unit time of an absolute value of each current flowing through the two capacitors, the first information and the second information indicating the current flowing through the capacitor, and the capacitor A capacitor control device that derives the target current value of each capacitor based on the coefficient obtained from the first information and the second information indicating internal resistance.

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