Control system and control method

Abstract

To provide a control system and a control method capable of accurately controlling charging / discharging of a power storage device.SOLUTION: A control system includes: a power storage device; a current detection unit configured to detect a charging / discharging current of the power storage device; and a charging / discharging control unit configured to control charging / discharging of the power storage device such that a detected charging / discharging current value matches a predetermined current command value. The charging / discharging control unit corrects control of charging / discharging of the power storage device such that a deviation between a second charge amount obtained based on the current command value and a cycle and a first charge amount obtained based on a capacitance of the power storage device and an amount of change in a terminal voltage of the power storage device in the predetermined cycle with the first charge amount being a feedback value.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present disclosure relates to a control system and a control method. [Background technology]

[0002] The vehicle power supply device described in Patent Document 1 includes a power storage device, a current sensor that detects the charge / discharge current of the power storage device, a voltage sensor that detects the voltage of the power storage device, and a control device that controls charging / discharging of the power storage device by receiving outputs from the current sensor and the voltage sensor. The control device calculates a control current value for control by subtracting an offset value from the detection value of the current sensor. The control device also calculates a first determination result that determines whether the power storage device is charging or discharging using the control current value, and a second determination result that determines whether the power storage device is charging or discharging from a change in the remaining capacity of the power storage device calculated from the output of the voltage sensor. If the first determination result and the second determination result differ, the control device changes the offset value so that the first determination result matches the second determination result.

[0003] Since the remaining capacity (SOC) of the power storage device is calculated using the output of a voltage sensor, even if an offset error occurs in the control current value of the current sensor, the change will often be in the correct direction (increasing during charging and decreasing during discharging).For this reason, in the vehicle power supply device described in Patent Document 1, the offset value used to correct the offset error of the current sensor that measures the current of the power storage device is changed in the correct direction, so it is said that even if the offset error of the current sensor fluctuates after the vehicle is started, it is possible to prevent overcharging or over-discharging of the power storage device.

[0004] In the vehicle power supply device described in Patent Document 1, the offset value is calculated by adding a correction value δi to the current offset correction value stored in the memory inside the control device. Furthermore, the correction value δi is calculated, for example, by measuring the maximum width of the change in the offset of the current sensor when a temperature change occurs within a predetermined range in the current sensor and current detection circuit, and then using this maximum width or a value obtained by dividing this maximum width by a certain number as the correction value δi. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-34796 Summary of the Invention [Problem to be solved by the invention]

[0006] As described above, in the vehicle power supply device described in Patent Document 1, when a first determination result of whether the power storage device is charging or discharging differs from a second determination result of whether the power storage device is charging or discharging based on a change in the remaining capacity of the power storage device calculated from the output of a voltage sensor, the offset value is changed so that the first determination result matches the second determination result. Furthermore, in this power supply device, whether or not to perform a correction is determined based on whether the first determination result and the second determination result differ, and the offset value is changed by a predetermined correction value based on the determination result. Therefore, there has been a problem in that if the predetermined correction value is inappropriate, it may not be possible to accurately control the charging and discharging of the power storage device.

[0007] The present disclosure has been made to solve the above-mentioned problems, and has an object to provide a control system and a control method that can accurately control the charging and discharging of a power storage device. [Means for solving the problem]

[0008] In order to solve the above problem, the control system of the present disclosure includes a power storage device, a current detection unit that detects the charge / discharge current of the power storage device, and a charge / discharge control unit that controls the charge / discharge of the power storage device so that the detected charge / discharge current value matches a predetermined current command value, and the charge / discharge control unit uses a first charge amount calculated based on the capacitance of the power storage device and the amount of change in the terminal voltage of the power storage device over a predetermined period as a feedback value, and corrects the control of the charge / discharge of the power storage device so that the deviation between the first charge amount and a second charge amount calculated based on the current command value and the period is reduced.

[0009] In addition, the control method disclosed herein uses a power storage device, a current detection unit that detects the charge / discharge current of the power storage device, and a charge / discharge control unit that controls the charge / discharge of the power storage device so that the detected charge / discharge current value matches a predetermined current command value, and corrects the control of the charge / discharge of the power storage device by the charge / discharge control unit, using a first charge amount calculated based on the capacitance of the power storage device and the amount of change in the terminal voltage of the power storage device over a predetermined period as a feedback value, so as to reduce the deviation between the first charge amount and a second charge amount calculated based on the current command value and the period. [Effects of the Invention]

[0010] According to the control system and control method of the present disclosure, it is possible to accurately control the charging and discharging of the power storage device. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a block diagram illustrating a configuration example of a control system according to an embodiment of the present disclosure. [Figure 2] 1 is a circuit diagram illustrating a configuration example of a power storage device according to an embodiment of the present disclosure. [Figure 3] FIG. 10 is a circuit diagram illustrating another configuration example of the power storage device according to the embodiment of the present disclosure. [Figure 4] 2 is a block diagram showing an example of the configuration of the DC-DC converter and a current detection unit shown in FIG. 1. FIG. [Figure 5]1. FIG. 4 is a block diagram showing another example of the configuration of the DC-DC converter and the current detection unit shown in FIG. [Figure 6] 2 is a block diagram showing an example of the configuration of a charge / discharge control unit shown in FIG. 1. FIG. [Figure 7] 1. FIG. 4 is a block diagram showing another example of the configuration of the charge / discharge control unit shown in FIG. [Figure 8] FIG. 2 is a circuit diagram illustrating an example of an equivalent circuit of a power storage device according to an embodiment of the present disclosure. [Figure 9] FIG. 4 is a diagram showing an example of SOC-voltage characteristics of a power storage device according to an embodiment of the present disclosure. [Figure 10] FIG. 4 is a diagram showing an example of SOC-capacitance characteristics of a power storage device according to an embodiment of the present disclosure. [Figure 11] FIG. 4 is a diagram illustrating an example of terminal voltage-capacitance characteristics of a power storage device according to an embodiment of the present disclosure. [Figure 12] FIG. 10 is a diagram illustrating an example of operation in a comparative example of the embodiment of the present disclosure. [Figure 13] FIG. 10 is a diagram illustrating an example of operation of an embodiment of the present disclosure. [Figure 14] FIG. 10 is a diagram illustrating an example of operation in a comparative example of the embodiment of the present disclosure. [Figure 15] FIG. 10 is a diagram illustrating an example of operation of an embodiment of the present disclosure. [Figure 16] FIG. 10 is a diagram illustrating an example of operation in a comparative example of the embodiment of the present disclosure. [Figure 17] FIG. 10 is a diagram illustrating an example of operation of an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In each drawing, the same or corresponding components are designated by the same reference numerals, and the description thereof will be omitted as appropriate.

[0013] FIG. 1 is a block diagram illustrating an example configuration of a control system 1 according to an embodiment of the present disclosure. The control system 1 illustrated in FIG. 1 constitutes a control system for a hybrid system of a vehicle, such as a work machine, such as a hybrid hydraulic excavator. However, the control system 1 is not limited to vehicles such as work machines, and can be applied, for example, as a hybrid system for a general vehicle. The control system 1 illustrated in FIG. 1 includes an operation unit 10, a power storage device 20, and a control device 30. The operation unit 10 is configured to control the charge / discharge current of the power storage device 20, which is one of the control targets of the control system 1, and includes a DC / DC converter 11, a generator motor drive device 12, a generator motor 13, and an engine 14. The DC / DC converter 11, the generator motor drive device 12, the generator motor 13, and the engine 14 each include multiple sensors (not shown), output a sensor signal SS to the control device 30, receive multiple control signals CNS output by the control device 30, and operate in accordance with the control signals CNS.

[0014] The control device 30 can be configured using a computer (CPU (Central Processing Unit)) such as a microcontroller, and includes a charge / discharge control unit 31 and other functional blocks configured by a combination of hardware such as a computer and software such as a program executed by the computer. The charge / discharge control unit 31 also includes a current detection unit 32. The control device 30 controls the DC / DC converter 11, the generator motor drive device 12, the generator motor 13, and the engine 14, for example, by receiving a plurality of sensor signals SS and outputting a plurality of control signals CNS. The control device 30 may also be configured by a plurality of control devices that control the DC / DC converter 11, the generator motor drive device 12, the generator motor 13, and the engine 14, and one or more control devices that perform integrated control of these devices.

[0015] The power storage device 20 is a device that stores DC power, and is, for example, a secondary battery 20a such as a lithium ion battery (LiB) having a plurality of cells 23 connected in series between terminals 21 and 22 as shown in FIG. 2. Alternatively, the power storage device 20 is, for example, a capacitor 20b such as an electric double layer capacitor (EDLC) or a lithium ion capacitor (LiC) having a plurality of cells 24 connected in series between terminals 21 and 22 as shown in FIG. 3. Note that the connection of the cells is not limited to series, and may be a combination of series and parallel connection, etc. Note that FIGS. 2 and 3 are circuit diagrams showing a configuration example of the power storage device 20 according to an embodiment of the present disclosure. The power storage device 20 may also include one or more sensors, such as a temperature sensor (not shown), and output a sensor signal SS indicating the detection results of the one or more sensors to the control device 30.

[0016] The DC-DC converter 11 includes a bidirectional DC-DC (DC-DC) converter. The DC-DC converter 11 receives a DC current I2 output from the generator motor drive device 12, converts a secondary voltage V2 to a primary voltage V1, and outputs the DC current I1 to charge the power storage device 20. The DC-DC converter 11 also receives a DC current I1 discharged from the power storage device 20, converts the primary voltage V1 to a secondary voltage V2, and outputs the DC current I2 to supply to the generator motor drive device 12. Hereinafter, the current I1 will also be referred to as a charge / discharge current I1, a primary current I1, etc. The current I1 is defined as a charging current when negative and a discharging current when positive. The DC-DC converter 11 may be, for example, a two-phase boost chopper-type DC-DC converter 11a shown in FIG. 4 or a DAB (Dual Active Bridge Converter) DC-DC converter 11b shown in FIG. 5. The DC-DC converter 11a shown in FIG. 4 and the DC-DC converter 11b shown in FIG. 5 are phase-controlled by switching control using a gate drive signal (PWM (pulse width modulation) signal) input as a control signal CNS from the control device 30, for example.

[0017] Fig. 4 is a block diagram showing an example of the configuration of the DC-DC converter 11 and the current detection unit 32 shown in Fig. 1. Fig. 5 is a block diagram showing another example of the configuration of the DC-DC converter 11 and the current detection unit 32 shown in Fig. 1.

[0018] The DC-DC converter 11a shown in FIG. 4 includes transistors T1, T2, T3, and T4, capacitors C1 and C2, inductors L1 and L2, and current sensors CS1 and CS2. The transistors T1 to T4 are, for example, IGBTs (Insulated Gate Bipolar Transistors) having freewheeling diodes between their collectors and emitters. The emitter of transistor T1 and the collector of transistor T2 are connected, and the connection point is connected to one end of inductance L1 via current sensor CS1. The emitter of transistor T3 and the collector of transistor T4 are connected, and the connection point is connected to one end of inductance L2 via current sensor CS2. The other end of inductance L1 and the other end of inductance L2 are connected to one end of capacitor C1. The collectors of transistors T1 and T3 are connected to one end of capacitor C2, and the emitters of transistors T2 and T4 are connected to the other end of capacitor C2 and C1. Current sensors CS1 and CS2 detect the currents flowing through inductors L1 and L2, respectively, in a non-contact manner using, for example, Hall sensors, and output analog signals indicating the polarity and magnitude of the detected currents.

[0019] The current detection unit 32 shown in FIG. 4 includes a detection filter 321 and an A / D (analog / digital) conversion unit 322. The detection filter 321 receives an analog signal output by the current sensor CS1, attenuates the signal in a predetermined frequency band, and outputs the signal to the A / D conversion unit 322. The A / D conversion unit 322 receives the output signal from the detection filter 321, converts it into a digital signal, and outputs it. In this embodiment, the sum of the detected values ​​of the primary current I1 by the current sensors CS1 and CS2 (and the detected value by the current sensor CS3, which will be described later) is referred to as the primary current (I1) detected value I1s. Note that while FIG. 4 only shows the detection filter 321 and the A / D conversion unit 322 for the current sensor CS1, the current detection unit 32 also includes a detection filter 321 and an A / D conversion unit 322 for the current sensor CS2, and calculates the I1 detected value I1s by summing the detected value Ic1s by the current sensor CS1 and the detected value Ic2s by the current sensor CS2.

[0020] The DC-DC converter 11b shown in FIG. 5 includes transistors T5-T12, capacitors C1 and C2, an inductor L3, a current sensor CS3, and an isolation transformer T1. The transistors T5-T12 are, for example, IGBTs with freewheeling diodes between their collectors and emitters. The transistors T5-T8 and the transistors T9-T12 each form an H-bridge circuit. The AC terminals of the transistors T5-T8 are connected to a series circuit of the inductor L3 and the primary winding of the isolation transformer T1, and the AC terminals of the transistors T9-T12 are connected to the secondary winding of the isolation transformer T1. The collectors of the transistors T5 and T7 are connected to one end of the capacitor C1 via the current sensor CS3, and the emitters of the transistors T6 and T8 are connected to the other end of the capacitor C1. The collectors of transistors T9 and T11 are connected to one end of capacitor C2, and the emitters of transistors T10 and T12 are connected to the other end of capacitor C2. Current sensor CS3 detects the current flowing between one end of capacitor C3 and the collectors of transistors T5 and T7 in a non-contact manner, using, for example, a Hall sensor, and outputs an analog signal representing the polarity and magnitude of the detected current. The current detection unit 32 shown in FIG. 5 includes a detection filter 321 and an A / D conversion unit 322. The current detection unit 32 shown in FIG. 5 receives the analog signal output by current sensor CS3 and outputs a detection value Ic3s. In the configuration shown in FIG. 5, this detection value Ic3s is the primary current (I1) detection value I1s.

[0021] 4 and 5, the current detection unit 32 does not include the current sensors CS1 to CS3, but the current detection unit 32 may include the current sensors CS1 to CS3. In other words, the "current detection unit" according to the present disclosure may include a detection filter and an A / D conversion unit in the control device 30 (charge / discharge control unit 31), and the current sensors CS (CS1 to CS3) in the DC / DC converter 11.

[0022] The generator motor drive device 12 is equipped with, for example, a bidirectional inverter, and controls the generator motor 13 as a generator to convert the AC power generated by the generator motor 13 into DC power and supply it to the DC-DC converter 11, or controls the generator motor 13 as an electric motor to start or assist the engine 14 using the generator motor 13, or to drive, for example, a vehicle or auxiliary equipment while the engine 14 is stopped.

[0023] The engine 14 is an internal combustion engine such as a diesel engine, a gasoline engine, or a hydrogen engine, and a control device 30 controls the fuel injection amount, rotation speed (rotational speed), and the like.

[0024] The operating unit 10 may also include a power splitting mechanism between the generator motor 13 and the engine 14 (not shown), and the operation of these components is also controlled by the control device 30.

[0025] Next, the charge / discharge control unit 31 shown in FIG. 1 will be described with reference to FIGS. 6 to 11. FIG. 6 is a block diagram showing an example of the configuration of the charge / discharge control unit 31 shown in FIG. 1. FIG. 7 is a block diagram showing another example of the configuration of the charge / discharge control unit 31 shown in FIG. 1. FIG. 8 is a circuit diagram showing an example of an equivalent circuit of the power storage device 20 according to an embodiment of the present disclosure. FIG. 9 is a diagram showing an example of the SOC-voltage characteristics of the power storage device 20 according to an embodiment of the present disclosure. FIG. 10 is a diagram showing an example of the SOC-capacitance characteristics of the power storage device according to an embodiment of the present disclosure. FIG. 11 is a diagram showing an example of the terminal voltage-capacitance characteristics of the power storage device according to an embodiment of the present disclosure.

[0026] 6 includes a current detection unit 32, a primary current command value generation unit 33, a current value correction amount calculation unit 34, a subtractor 35, a subtractor 36, a proportional-plus-integral calculation unit 37, and a control signal generation unit 38. The primary current command value generation unit 33 generates and outputs a primary current command value I*1 that is a command value for the charge / discharge current I1 of the power storage device 20. The primary current command value I*1 is a control command value (target value) for the primary current I1, and the charge / discharge control unit 31 controls the operation unit 10 so that the I1 detection value I1s (detected charge / discharge current value) matches the corrected primary current command value I*1c, thereby controlling the charge / discharge of the power storage device 20.

[0027] The primary current command value generating unit 33 generates the primary current command value I*1 according to a predetermined rule depending on, for example, the SOC (State of Charge) of the power storage device 20, the driving conditions of the generator motor 13 and the engine 14, etc. Furthermore, secondary batteries such as LiC and LiB need to be charged (hereinafter also referred to as micro-charging) at a constant current that is more limited than the original performance (e.g., rated charge / discharge current) to prevent an increase in resistance due to deposition of Li (lithium) ions on the electrodes when the battery is over-discharged after being left unused for a long period of time. For this reason, for example, when an over-discharge state is detected, the primary current command value generating unit 33 generates and outputs the primary current command value I*1 for charging the power storage device 20 at a limited charging current value for a short period of time (e.g., several tens of seconds to several minutes) until the over-discharge state is resolved. Furthermore, the primary current command value generating unit 33 generates and outputs the primary current command value I*1 for charging the power storage device 20 at a limited charging current value (micro-charging) even when the power storage device 20 is in a predetermined extremely low temperature state. Charging (micro charging) with the charging current value limited is performed by setting the primary current command value I*1 to the current value to be limited, for example by putting the engine 14 into an idle state and causing the generator motor drive device 12 to generate electricity with the output of the generator motor 13 greatly limited relative to the maximum output, and controlling the DC-DC converter 11 so that the I1 detection value I1s matches the primary current command value I*1.

[0028] However, because the current value differs significantly between normal operation (e.g., ±300 A) and minute charging (e.g., −10 A), the rated values ​​of the current sensors CS1 to CS3 implemented in the DC-DC converters 11a and 11b are large for minute charging currents. Therefore, the adverse effect of current detection value errors in the DC-DC converters 11a and 11b on control performance and the like is greater during minute charging than during normal operation. To reduce this adverse effect, the charge / discharge control unit 31 of this embodiment corrects the charge / discharge control as follows. Specifically, the charge / discharge control unit 31 uses a first charge amount calculated based on the capacitance of the power storage device 20 and the amount of change in the terminal voltage V1 of the power storage device 20 over a predetermined period as a feedback value (correction index), and corrects the charge / discharge control of the power storage device 20 so as to reduce the deviation between the first charge amount and a second charge amount calculated based on a primary current command value I*1 (current command value) and its period. In this case, the second amount of charge is a target value (command value) for the first amount of charge (feedback value; controlled variable). However, "first" and "second" are terms used to distinguish between the two amounts of charge, and for example, "first" and "second" may be interchangeable. Therefore, the current value correction amount calculation unit 34 calculates the current value correction amount cor_I for correcting the control of charging and discharging of the power storage device 20. The current detection value error includes the temperature characteristics, offset error, gain error, etc. of the current sensors CS1 to CS3, as well as the offset error, quantization error, etc. of the A / D conversion unit 332.

[0029] Here, with reference to FIG. 8, the basic concept of how to calculate the current value correction amount cor_I will be described. As shown in FIG. 8, the power storage device 20 (referred to as power storage device 20c in FIG. 8) is represented by a series circuit of a capacitance C_CAP (the symbol "_" indicates that the character following it is a subscript) (actual value) and a resistance R. Here, the resistance R is a combined resistance of the internal resistance Ri and the bus bar resistance Rb, etc. The capacitance C_CAP (actual value) is the actual value of the capacitance of the power storage device 20. The actual value of the voltage applied to the cell of the power storage device 20 is represented as V_CAP (actual value), and the actual value of the charge / discharge current of the power storage device 20 is represented as I_CAP. The detection value of the sensor CS (CS1 to CS3) including an offset error, etc. is represented as I_CAP-SENS (=I1 detected value I1s), and the detection value of the terminal voltage of the power storage device 20 is represented as V_CAP-SENS (=V1 detected value).

[0030] The equations relating to the voltage and current of the storage device 20, including the actual value, the detected value, and the error value, can be expressed by the following formulas (1) to (3).

[0031]

number

[0032]

number

[0033]

number

[0034] The error values ​​(detection errors) I_ERR and V_ERR at this time can be regarded as offset errors (more precisely, they include white noise) if the temperature and detection range are the same over the control period T_STEP.

[0035] Furthermore, because the rate of change in the current value is small during minute charging, the amount of change in RI_CAP from the previous value in the control period T_STEP is also small. From these facts, the time change in equation (2) can be regarded as the following equation. Note that [n] indicates the value in the control period immediately before the [n+1]th control period.

[0036]

number

[0037] Substituting equation (2a) into equation (3) yields the following equation:

[0038]

number

[0039] If C_CAP in equation (3a) is replaced with the model value C_CAP-MODEL for estimating ΔQ_V, the charge change ΔQ_V based on the voltage detection can be expressed as follows:

[0040]

number

[0041] In addition, the charge change ΔQ_I when the primary current command value I*1 (=I_CAP-REF) is flowing can be expressed by the following equation.

[0042]

number

[0043] As will be described later, the operation unit 10, which functions as a current controller, matches the primary current command value I*1c and the detected current value I1s (=I_CAP-SENS) through current PI control (proportional + integral control). Therefore, the difference between the target value (command value) and the feedback value can be reduced by subtracting (or adding to) the current detection value the correction value (current value correction amount cor_I) obtained through charge change PI control with equation (5) as the command value and equation (4) as the feedback value from the current command value. However, even after the correction value is set, the modeling error of (C_CAP-C_CAP-MODEL) remains as a deviation. C_CAP-MODEL is a model value for estimating ΔQv of the capacitance of the storage device 20.

[0044] 6, the current value correction amount calculation unit 34 includes a ΔQ_I calculation unit 341, a ΔQ_V calculation unit 342, a subtractor 343, a proportional-plus-integral calculation unit 344, and a limiter 345. The ΔQ_I calculation unit 341 includes a multiplier 3411 that multiplies a primary current command value I*1 (=I_CAP-REF) by a constant 3412 that represents a calculation period T_STEP of the current value correction amount cor_I, and calculates, as the output of the multiplier 3411, a change amount ΔQ_I ("second amount of charge" in this disclosure) in the amount of charge for the period T_STEP calculated based on the primary current command value I*1 (current command value) and the period T_STEP.

[0045] Furthermore, ΔQ_V calculation unit 342 includes a multiplier 3421, a subtractor 3422, a delay element 3423, and a C_CAP-MODEL estimated value calculation unit 3424. C_CAP-MODEL estimated value calculation unit 3424 calculates and outputs a model value for estimating ΔQv of the capacitance of power storage device 20.

[0046] As shown in FIG. 9, the power storage device 20 has a certain relationship between the SOC and the terminal voltage. Furthermore, as shown in FIG. 10, the power storage device 20 has a certain relationship between the SOC and the capacitance. Furthermore, if the power storage device 20 is an LiC, the relationship between the SOC and the capacitance can be defined as being approximately linear. If the power storage device 20 is an LiB, the relationship between the SOC and the capacitance can be defined using, for example, a table. The C_CAP-MODEL ΔQv estimation model value calculation unit 3424 can calculate and output the capacitance ΔQv estimation model value C_CAP-MODEL using, for example, a table (or function) for calculating the SOC from the V1 detected value (=V_CAP-SENS) (terminal voltage) and a table (or function) for calculating the capacitance from the SOC. In this case, for example, the SOC can first be calculated based on the terminal voltage using a table for calculating the SOC from the terminal voltage, and then the ΔQv estimation model value can be calculated based on the calculated SOC using a table for calculating the capacitance from the SOC. Alternatively, for example, a table for calculating SOC from terminal voltage can be prepared, and the ΔQv estimation model value can be calculated based on the terminal voltage using this table. The correspondence between the terminal voltage or SOC and the ΔQv estimation model value does not have to be continuous or stepwise, e.g., three or more steps. As long as there is a correspondence between at least two or more different ΔQv estimation model values ​​and multiple different terminal voltage or SOC values, ΔQv can be calculated more accurately than when a single fixed ΔQv estimation model value defined independently of SOC or terminal voltage is used. In this case, the capacitance is defined to have two or more different values ​​corresponding to multiple different SOC or terminal voltage values. When the power storage device 20 is an LiC, the ΔQv estimation model value of the capacitance can be a fixed value, as shown in FIG. 11 .

[0047] The ΔQ_V calculation unit 342 calculates the change in the charge amount ΔQ_V (the "first charge amount" in this disclosure) between the control periods T_STEP by multiplying the value obtained by subtracting the previous V1 detection value output by the delay element 3423 from the current V1 detection value using a subtractor 3422 and the result by the model value C_CAP-MODEL for estimating the capacitance ΔQv using a multiplier 3421.

[0048] A subtractor 343 subtracts ΔQ_V (first charge amount) calculated by a ΔQ_V calculation unit 342 from ΔQ_I (second charge amount) calculated by a ΔQ_I calculation unit 341, thereby calculating a deviation ΔQ_d between ΔQ_I (second charge amount) and ΔQ_V (first charge amount) in charge change PI control, with ΔQ_V (first charge amount) as a feedback value and ΔQ_I (second charge amount) as a target value. A proportional-plus-integral calculation unit 344 generates a control signal by proportional and integral action based on the deviation ΔQ_d, and a limiter 345 outputs a value obtained by limiting the output of the proportional-plus-integral calculation unit 344 within a predetermined range as a current value correction amount cor_I. The range limited by the limiter 345 can be, for example, a range that can occur as a current detection value error.

[0049] The subtractor 35 subtracts the current value correction amount cor_I from the primary current command value I*1 (current command value) to calculate and output a primary current command value I*1c, which is the corrected primary current command value I*1 (current command value).

[0050] A subtractor 36 calculates and outputs a current value deviation d_I1 by subtracting the I1 detection value I1s from the primary current command value I*1c. A proportional-plus-integral calculator 37 generates a control signal by proportional and integral action based on the current value deviation d_I1, and a control signal generator 38 converts the signal into one or more control signals CNS for the operation unit 10 and outputs the signal to the operation unit 10.

[0051] Next, with reference to FIG. 7, another configuration example of the charge / discharge control unit 31 (hereinafter referred to as 31b) will be described. In the charge / discharge control unit 31 (31a) shown in FIG. 6, the charge / discharge current control is corrected by subtracting the current value correction amount cor_I from the primary current command value I*1. In contrast, the charge / discharge control unit 31 (31b) corrects the charge / discharge current control by adding the current value correction amount cor_I to the I1 current detection value I1s. The charge / discharge control unit 31 (31b) does not include the subtractor 35 shown in FIG. 1, and instead includes an adder 39 between the current detection unit 32 and the subtractor 36. The adder 39 adds the current value correction amount cor_I and the I1 current detection value I1s and outputs a current detection value I1sc, which is the corrected current detection value I1s. The subtractor 36 then subtracts the I1 detection value I1sc from the primary current command value I*1 to calculate and output a current value deviation d_I1.

[0052] The results of verifying the effects of this embodiment will be described with reference to FIGS. 12 to 17. FIGS. 12, 14, and 16 show examples of operation verification in a comparative example, and FIGS. 13, 15, and 17 show examples of operation verification results when correcting the primary current command value I*1 shown in FIG. 6 in this embodiment. In all cases, the horizontal axis represents time and the vertical axis represents the terminal voltage (V1) and charge / discharge current (I1) of the power storage device 20. The primary current command value I*1 is constant, and comparisons are made between a case where there is no current error, a case where the current error is +ΔI, and a case where the current error is −ΔI. When there is no current error, no significant difference is observed between the actual value and the command value (after correction) when the correction shown in FIG. 12 is not performed and when the correction shown in FIG. 13 is performed. When the current error is +ΔI, a significant difference is observed between the actual value and the command value (after correction) when the correction shown in FIG. 14 is not performed and when the correction shown in FIG. 15 is performed. When the current error is −ΔI, a large difference is observed between the actual value and the command value (after correction) when the correction shown in Fig. 16 is not performed and when the correction shown in Fig. 17 is performed. Note that in the operation example shown in Fig. 16, over-discharge occurs.

[0053] As described above, the control system 1 of this embodiment includes the power storage device 20, the current detection unit 32 that detects the charge / discharge current (I1 detection value I1s) of the power storage device 20, and the charge / discharge control unit 31 that controls the charge / discharge of the power storage device 20 so that the detected charge / discharge current value matches a predetermined current command value (primary current command value I*1).The charge / discharge control unit 31 corrects the control of the charge / discharge of the power storage device 20 so that the deviation (ΔQ_d) between the second charge (ΔQ_I) calculated based on the current command value (primary current command value I*1) and the period (T_STEP) and the first charge (ΔQ_V) is reduced, using the first charge (ΔQ_V) calculated based on the capacitance (C_CAP-MODEL) of the power storage device 20 and the amount of change in the terminal voltage (V1 detection value) of the power storage device 20 in a predetermined period (T_STEP) as a feedback value. According to this configuration, the control of charging and discharging of the power storage device 20 can be corrected based on the deviation in the feedback control, and the charging and discharging of the power storage device 20 can be controlled with high precision.

[0054] In addition, the charge / discharge control unit 31 corrects the charge / discharge control by correcting the current command value (primary current command value I*1) or the detected charge / discharge current value (I1 detection value I1s) so that the deviation (ΔQ_d) becomes smaller.

[0055] Furthermore, the capacitance (C_CAP-MODEL) is a model value previously determined as a table, function, or constant for voltage or voltage and SOC in order to calculate the first charge quantity (ΔQ_V). The model value may be, for example, a standard value obtained by actual measurement. The standard value may be set as a function or table according to the terminal voltage, etc. That is, in this embodiment, for example, it is defined to have two or more different values ​​for different values ​​of SOC or terminal voltage.

[0056] Furthermore, the capacitance (C_CAP-MODEL) is, for example, a fixed value obtained in advance.

[0057] Furthermore, according to this embodiment, for a small current that is less than 1 / 10 of the rated current of the current sensor, the influence of current detection errors can be suppressed without adding an additional sensor.

[0058] Moreover, the above control can be implemented by simple PI control (ease of design).

[0059] Although the embodiments of the present invention have been described above with reference to the drawings, the specific configuration is not limited to the above-described embodiments, and design modifications and the like are also included within the scope of the gist of the present invention. Furthermore, part or all of the programs executed by the computer in the above-described embodiments can be distributed via computer-readable recording media or communication lines. Although the above embodiment illustrates an example in which the present disclosure is applied to a vehicle hybrid system, the application field of the present disclosure is not limited to vehicle hybrid systems. The present disclosure can be applied to a general control system including a power storage device, a current detection unit that detects a charge / discharge current of the power storage device, and a charge / discharge control unit that controls the charge / discharge of the power storage device so that the detected charge / discharge current value matches a predetermined current command value. The present disclosure can also be applied to charging a power storage device using an external power source, such as a commercial power source. Therefore, for example, the present disclosure can be applied to electric work machines, such as electric hydraulic excavators, that are driven by a power storage device, and electric vehicles. When charging a power storage device using an external power source, for example, the AC terminals of the generator motor drive device 12 can be switched from the generator motor 13 to an external AC power source, or the secondary terminals of the DC / DC converter 11 can be switched from the generator motor drive device 12 to an external DC power source.

[0060] [Note] The control system 1 described in the embodiment can be understood as follows.

[0061] (1) A control system according to a first aspect of the present disclosure includes a power storage device, a current detection unit that detects a charge / discharge current of the power storage device, and a charge / discharge control unit that controls the charging / discharging of the power storage device so that the detected charge / discharge current value matches a predetermined current command value. The charge / discharge control unit uses a first charge amount calculated based on the capacitance of the power storage device and the amount of change in the terminal voltage of the power storage device over a predetermined period as a feedback value, and corrects the control of the charging / discharging of the power storage device so that the deviation between the first charge amount and a second charge amount calculated based on the current command value and the period is reduced.

[0062] (2) A control system according to a second aspect of the present disclosure is the control system of (1), wherein the charge / discharge control unit corrects the charge / discharge control by correcting the current command value or the detected charge / discharge current value so as to reduce the deviation.

[0063] (3) A control system according to a third aspect of the present disclosure is a control system according to (1) or (2), in which the capacitance is defined to have two or more different values ​​for different values ​​of SOC or the terminal voltage.

[0064] (4) A control system according to a fourth aspect of the present disclosure is the control system of (1) to (3), wherein the capacitance is a fixed value obtained in advance. [Explanation of symbols]

[0065] 1... control system, 20... power storage device, 30... control device, 31... charge / discharge control section, 32... current detection section

Claims

1. a power storage device; a current detection unit that detects a charge / discharge current of the power storage device; a charge / discharge control unit that controls charging / discharging of the power storage device so that the detected charge / discharge current value coincides with a predetermined current command value; Equipped with The charge / discharge control unit corrects control of the charge / discharge of the power storage device so that a deviation between a second charge amount calculated based on the current command value and the period and the first charge amount becomes small, using a first charge amount calculated based on the capacitance of the power storage device and a change amount in a predetermined period of a terminal voltage of the power storage device as a feedback value. Control system.

2. The charge / discharge control unit corrects the charge / discharge control by correcting the current command value or the detected charge / discharge current value so as to reduce the deviation. The control system of claim 1 .

3. The capacitance is defined to have two or more different values ​​for different values ​​of SOC (State Of Charge) or the terminal voltage. The control system of claim 2 .

4. The capacitance is a predetermined fixed value. A control system according to any one of claims 1 to 3.

5. a power storage device; a current detection unit that detects a charge / discharge current of the power storage device; a charge / discharge control unit that controls charging / discharging of the power storage device so that the detected charge / discharge current value coincides with a predetermined current command value; Using The charge / discharge control unit corrects the control of charge / discharge of the power storage device so that a deviation between a second charge amount calculated based on the current command value and the period and the first charge amount becomes small, using a first charge amount calculated based on the capacitance of the power storage device and the amount of change in the terminal voltage of the power storage device in a predetermined period as a feedback value. Control method.

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