Battery state measurement device and power source system using the same

Abstract

To provide a power source system capable of measuring a battery state such as impedance of a battery included in each battery module without stopping operation of the system.SOLUTION: A power source system 100 uses a group of battery modules 102 including a plurality of battery modules 102 having a battery, and is able to serially connect and disconnect batteries 10 in the plurality of battery modules 102 based on a gate drive signal from a control controller 104, where each battery module 102 comprises an impedance measuring device 30; the battery 10 in the battery module 102 that has been disconnected from the series connection is defined as a measurement target; an impedance measurement device 30 measures a battery state of the battery 10 to be measured; and the battery 10 to be measured is controlled according to the battery state.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a battery state measuring device and a power supply system using the same. [Background technology]

[0002] 2. Description of the Related Art Power supply systems that use a plurality of battery modules to stably supply power to a load are widely used.

[0003] A storage battery system capable of measuring the capacity of storage batteries individually in parallel with operation without stopping the operation has been disclosed (Patent Document 1). A plurality of storage battery panels include an operation side contactor having one end connected to an operation PCS, a storage battery to which the other end of the operation side contactor is connected, and a storage battery monitoring unit that monitors the state of the storage battery. The operation side contactor of a target storage battery panel to be subjected to capacity measurement among the plurality of storage battery panels is opened, and only the capacity measurement side contactor connected to the target storage battery panel among the plurality of capacity measurement side contactors is closed to enter a capacity measurement mode, and the storage battery capacity is calculated from the storage battery information output from the storage battery monitoring unit of the target storage battery panel.

[0004] Also, a storage battery diagnostic device capable of notifying the deterioration state of a storage battery while performing charging and discharging with a simple configuration has been disclosed (Patent Document 2). The storage battery diagnostic device includes a SOC acquisition unit that acquires the SOC of the storage battery, a temperature acquisition unit that acquires the temperature of the storage battery, a storage unit that stores deterioration rate characteristics that indicate the relationship between the temperature and SOC of the storage battery and the deterioration rate, a diagnostic unit that specifies the deterioration rate of the storage battery based on the acquired temperature, SOC, and deterioration rate characteristics and calculates the deterioration level of the storage battery by accumulating the deterioration rate for a predetermined period, and an output unit that outputs information regarding the deterioration state of the storage battery based on the deterioration level.

[0005] A power supply system that makes it possible to accurately diagnose the capacity degradation of a battery while securing backup power has been disclosed (Patent Document 3).The power supply system includes an uninterruptible power supply having a secondary battery, and a diagnostic device that diagnoses the capacity degradation of the secondary battery of the uninterruptible power supply, where the uninterruptible power supply operates in a normal mode in which the secondary battery can be charged to a first charging state, and a diagnostic mode in which the secondary battery can be charged to a second charging state higher than the first charging state, and the diagnostic device switches the uninterruptible power supply from the normal mode to the diagnostic mode and diagnoses the capacity degradation of the secondary battery of the uninterruptible power supply by using a capacity region between the first charging state and the second charging state. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2019-158397 A [Patent Document 2] JP 2020-038138 A [Patent Document 3] JP 2020-102343 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, if metal deposition occurs in a battery cell included in a power supply system, the battery may malfunction. In order to improve the safety of the power supply system and maximize the performance of the battery cells, it is desirable to have battery control that detects metal deposition and delays or prevents the deposition from occurring.

[0008] It is also desirable to be able to measure the AC impedance of each battery without stopping the operation of the entire power supply system. Also, there is a need for technology that can individually control the batteries included in the power supply system according to the state of each battery. [Means for solving the problem]

[0009] One aspect of the present invention is a power supply system that uses a battery module group including a plurality of battery modules each having a battery, and is capable of connecting and disconnecting the batteries in the plurality of battery modules in series with each other based on a gate drive signal from a control controller, and is characterized in that the power supply system is equipped with an impedance measuring device in each of the battery modules, and the battery in the battery module that has been disconnected from the series connection is treated as a measurement object, the impedance measuring device measures the battery state of the battery that is the measurement object, and control is performed on the battery that is the measurement object in accordance with the battery state.

[0010] Here, when the battery state is abnormal, it is preferable to suppress the progression of the abnormal state by individually controlling the current flowing through the batteries to be measured.

[0011] Furthermore, when the battery state is abnormal, it is preferable that the battery to be measured can be forcibly disconnected from the series connection without shutting down the power supply system.

[0012] In addition, it is preferable that the abnormal state is a state in which metal is precipitated in the battery to be measured, or a state in which the battery to be measured is damaged.

[0013] It is also preferable that the impedance measuring device uses a resonant circuit to cause an AC current to oscillate at a damped rate, and measures the impedance according to a damping rate of the damped oscillation.

[0014] In addition, it is preferable that the impedance measuring device includes a peak hold circuit that acquires the peak value of any maximum or minimum peak contained in the damped oscillation, and that the maximum or minimum peak for which the peak value is to be acquired is set as a target peak, and that the process of starting to hold the value of the damped oscillation at a time before the target peak and stopping to hold the value of the damped oscillation at a time after the target peak is repeated for a plurality of the damped oscillations.

[0015] It is also preferable that the impedance measuring device estimates the amount of metal deposition in the battery from the amount of decrease in the measured real impedance.

[0016] It is also preferable that the impedance measuring device estimates the internal temperature of the battery from the amount of decrease in at least one of the measured real impedance part and imaginary impedance part.

[0017] It is also preferable that a plurality of battery module groups are used, AC output is possible, and the reactive power of each battery is individually controlled to adjust the temperature of the battery. Effect of the Invention

[0018] According to the present invention, in a power supply system, it is possible to measure the battery state, such as the impedance of the battery included in each battery module, without stopping the operation of the system. Also, it is possible to individually control each battery module according to the state of the battery included in each battery module. [Brief description of the drawings]

[0019] [Figure 1] 1 is a diagram showing a basic configuration of a power supply device according to an embodiment of the present invention. [Diagram 2] 4 is a time chart illustrating control of a battery module according to an embodiment of the present invention. [Diagram 3] 5A to 5C are diagrams illustrating the operation of the battery module according to the embodiment of the present invention. [Figure 4] 4 is a time chart illustrating control of the power supply device according to the embodiment of the present invention. [Diagram 5] 1 is a diagram showing a configuration of an impedance measuring device according to an embodiment of the present invention. [Figure 6] 5 is a flowchart showing a peak hold process according to the embodiment of the present invention. [Figure 7] FIG. 4 is a diagram showing a sequence of a peak hold process in the embodiment of the present invention. [Figure 8] 5A and 5B are diagrams illustrating an example of a time change in a damped oscillation waveform of a resonant voltage in the embodiment of the present invention. [Figure 9] FIG. 2 is a diagram illustrating an example of a peak hold circuit according to an embodiment of the present invention. [Figure 10] FIG. 2 is a diagram illustrating an example of a peak hold circuit according to an embodiment of the present invention. [Figure 11] FIG. 2 is a diagram illustrating an example of a peak hold circuit according to an embodiment of the present invention. [Figure 12] FIG. 2 is a diagram illustrating an example of a peak hold circuit according to an embodiment of the present invention. [Figure 13] FIG. 4 is a diagram showing the relationship between the impedance and the amount of lithium deposition of a battery according to an embodiment of the present invention. [Figure 14] FIG. 4 is a diagram showing the relationship between impedance and internal temperature of a battery according to an embodiment of the present invention. [Figure 15] 1 is a diagram showing a configuration of a three-phase AC power supply according to an embodiment of the present invention. [Figure 16] FIG. 2 is a diagram showing AC voltages in a three-phase balanced state outputted from a three-phase AC power supply in the embodiment of the present invention. [Figure 17] 3 is a flowchart showing an impedance measuring method according to an embodiment of the present invention. [Figure 18] FIG. 2 is a diagram illustrating reactive power in an AC power supply. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] [Basic configuration of power supply circuit] 1, a power supply system 100 (power supply module group) in this embodiment includes a battery module 102 and a controller 104. The power supply system 100 includes a plurality of battery modules 102 (102a, 102b, . . . 102n). The plurality of battery modules 102 included in the power supply system 100 can supply power (power running) to a load (not shown) connected to terminals T1 and T2, or charge (regenerate) power from a power supply (not shown) connected to terminals T1 and T2.

[0021] The battery module 102 includes a battery 10, a choke coil 12, a capacitor 14, a first switch element 16, a second switch element 18, a delay circuit 20, and a signal processing circuit 22. In this embodiment, each battery module 102 has the same configuration. The batteries 10 in the battery modules 102 included in each power supply system 100 can be connected in series with each other under the control of a controller 104.

[0022] The battery 10 includes at least one secondary battery. The battery 10 can be configured by connecting, for example, a plurality of lithium ion batteries, nickel metal hydride batteries, etc. in series and / or in parallel. The choke coil 12 and the capacitor 14 form a smoothing circuit (low-pass filter circuit) that smoothes and outputs the output from the battery 10. That is, since a secondary battery is used as the battery 10, an RLC filter is formed by the battery 10, the choke coil L, and the capacitor 14 to level the current in order to suppress deterioration of the battery 10 due to an increase in internal resistance loss. Note that the choke coil 12 and the capacitor 14 are not essential components and may not be provided.

[0023] The first switch element 16 includes a switch element for short-circuiting the output terminal of the battery 10. In this embodiment, the first switch element 16 is configured by connecting a free-wheeling diode in parallel to a field-effect transistor serving as a switch element. The second switch element 18 is connected in series to the battery 10 between the battery 10 and the first switch element 16. In this embodiment, the second switch element 18 is configured by connecting a free-wheeling diode in parallel to a field-effect transistor serving as a switch element. The first switch element 16 and the second switch element 18 are switched by a gate drive signal from the controller 104. In this embodiment, the first switch element 16 and the second switch element 18 are field-effect transistors, but are not limited to this as long as they are configured to be switched. For example, the first switch element 16 and the second switch element 18 may be other types of switch elements such as IGBTs.

[0024] The delay circuit 20 includes a delay circuit that delays the gate drive signal by a predetermined time. In the power supply system 100, a delay circuit 20 is provided for each battery module 102 (102a, 102b, . . . 102n), which are connected in series. Therefore, the gate drive signal input from the controller 104 is sequentially input to each battery module 102 (102a, 102b, . . . 102n) while being delayed by a predetermined time. Control based on the gate drive signal will be described later.

[0025] The signal processing circuit 22 is a circuit that controls the battery module 102 in response to a control signal input from the control controller 104 to the battery module 102. The signal processing circuit 22 is controlled by receiving a forced disconnection signal or a forced connection signal from the control controller 104. The signal processing circuit 22 constitutes a disconnection means that forcibly disconnects the batteries 10 in the battery module 102 from a series connection state in response to a forced disconnection signal from the control controller 104. The signal processing circuit 22 also constitutes a connection means that forcibly connects the batteries 10 in the battery module 102 to a series connection state in response to a forced connection signal from the control controller 104. A control signal from the control controller 104 is input to one input terminal of the signal processing circuit 22, and a gate drive signal from the delay circuit 20 is input to the other input terminal. An output signal from the signal processing circuit 22 is input to the gate terminal of the second switch element 18. An output signal from the signal processing circuit 22 is input to the gate terminal of the first switch element 16 via a NOT element.

[0026] During normal control, the gate drive signal from the signal processing circuit 22 is input directly to the gate terminal of the second switch element 18, and an inverted signal of the gate drive signal is input to the gate terminal of the first switch element 16. As a result, when the gate drive signal is at a high (H) level, the first switch element 16 is in an off state and the second switch element 18 is in an on state, and when the gate drive signal is at a low (L) level, the first switch element 16 is in an on state and the second switch element 18 is in an off state. That is, when the gate drive signal is at a high (H) level, the batteries 10 in the battery module 102 are connected in series with the batteries 10 in the other battery modules 102, and when the gate drive signal is at a low (L) level, the batteries 10 in the battery module 102 are in a through state in which they are disconnected from the batteries 10 in the other battery modules 102.

[0027] During forced disconnection, the controller 104 outputs a forced disconnection signal to the signal processing circuit 22 connected to the battery module 102 including the battery to be forcibly disconnected. The forced disconnection signal is transmitted to the signal processing circuit 22 of the battery module 102. A low (L) level is output from the signal processing circuit 22, a high (H) level is input to the gate terminal of the first switch element 16 by the NOT element, and a low (L) level is input to the gate terminal of the second switch element 18. Therefore, the first switch element 16 is always in the ON state, the second switch element 18 is always in the OFF state, and the batteries 10 in the battery module 102 are forcibly disconnected from the series connection (pass-through state) regardless of the state of the gate drive signal.

[0028] Such forced disconnection control can be utilized for control to suppress imbalance in SOC of the battery 10 in the battery module 102 in the power supply system 100. That is, when the power supply system 100 is in a discharging state, the SOC of the battery 10 in the battery module 102 involved in the output of the power supply system 100 decreases, but the SOC of the battery 10 in the battery module 102 can be maintained by forcibly disconnecting the battery 10 in the battery module 102. Also, when the power supply system 100 is in a charging state, the SOC of the battery 10 in the battery module 102 involved in the charging of the power supply system 100 increases, but the SOC of the battery 10 in the battery module 102 can be maintained by forcibly disconnecting the battery 10 in the battery module 102.

[0029] During forced connection, the controller 104 transmits a forced connection signal to the battery module 102 that includes the battery to be forcibly connected, causing a high (H) level to be output from the signal processing circuit 22, a low (L) level to be input to the gate terminal of the first switch element 16 by the NOT element, and a high (H) level to be input to the gate terminal of the second switch element 18. Therefore, the first switch element 16 is always in the OFF state, the second switch element 18 is always in the ON state, and the batteries 10 in the battery module 102 are forcibly connected in series regardless of the state of the gate drive signal.

[0030] Such forced connection control can be used for control to suppress imbalance in SOC of the batteries 10 in the battery modules 102 in the power supply system 100. That is, when the power supply system 100 is in a discharging state, the SOC of the batteries 10 in the battery modules 102 that are intermittently connected in series in response to the gate drive signal can be reduced more quickly in response to a decrease in the SOC of the batteries 10 in the battery modules 102 that are forced to be connected. Also, when the power supply system 100 is in a charging state, the SOC of the batteries 10 in the battery modules 102 that are forced to be connected can be increased more quickly in response to an increase in the SOC of the batteries 10 in the battery modules 102 that are intermittently connected in series in response to the gate drive signal.

[0031] [Normal control] The control of the power supply system 100 will be described below with reference to Fig. 2. The control controller 104 outputs a square wave gate drive signal to each battery module 102. The control controller 104 controls the entire battery module 102. In other words, the control controller 104 controls the output voltage of the power supply system 100 by controlling the multiple battery modules 102a, 102b, ... 102n.

[0032] The gate drive signal is transmitted to the delay circuit 20 included in the battery module 102a, the delay circuit 20 included in the battery module 102b, and so on, to the subsequent battery module 102. That is, the gate drive signal is delayed by a predetermined delay time in sequence from the most upstream side of the battery modules 102 connected in series in the power supply system 100 to the downstream side.

[0033] During normal control, the gate terminal of the first switch element 16 receives the gate drive signal from the delay circuit 20 as an inverted signal via a NOT element, and the gate terminal of the second switch element 18 receives the gate drive signal from the delay circuit 20 as is.

[0034] 2 shows a time chart relating to the operation of the battery module 102a. In addition, in FIG. 2, a pulse waveform of a gate drive signal D1 that drives the battery module 102a, a square wave D2 indicating the switching state of the first switch element 16, a square wave D3 indicating the switching state of the second switch element 18, and a voltage V output by the battery module 102a are shown. mod 4 shows waveform D4.

[0035] In the initial state of the battery module 102a, i.e., in a state where a gate drive signal is not output, the first switch element 16 is in an ON state and the second switch element 18 is in an OFF state. When a gate drive signal is input to the battery module 102a, the battery module 102a is subjected to switching control by PWM control. In this switching control, the first switch element 16 and the second switch element 18 are alternately switched between an ON state and an OFF state.

[0036] 2, when the gate drive signal D1 is output from the controller 104, the first switch element 16 and the second switch element 18 of the battery module 102a are driven in response to the gate drive signal D1. The first switch element 16 is switched from the ON state to the OFF state by the falling edge of the signal from the NOT element in response to the rising edge of the gate drive signal D1. The first switch element 16 is also switched from the OFF state to the ON state with a slight delay (dead time dt) from the falling edge of the gate drive signal D1.

[0037] On the other hand, the second switch element 18 switches from the OFF state to the ON state with a slight delay (dead time dt) from the rising edge of the gate drive signal D1. The second switch element 18 switches from the ON state to the OFF state simultaneously with the falling edge of the gate drive signal D1. In this way, the first switch element 16 and the second switch element 18 are switched between the ON state and the OFF state alternately.

[0038] The first switch element 16 operates with a slight delay (dead time dt) from the falling edge of the gate drive signal D1, and the second switch element 18 operates with a slight delay (dead time dt) from the rising edge of the gate drive signal D1 in order to prevent the first switch element 16 and the second switch element 18 from being turned on at the same time. In other words, this prevents the first switch element 16 and the second switch element 18 from being turned on at the same time, which would cause the battery 10 to be short-circuited. The dead time dt that delays this operation is set to, for example, 100 ns, but can be set appropriately. During the dead time dt, the current flows back through the diode, and the switch element in parallel with the diode through which the current flows is in the same state as when it is turned on.

[0039] By such control, when the gate drive signal D1 is off (i.e., the first switch element 16 is on and the second switch element 18 is off), the capacitor 14 and the battery 10 are disconnected from the output terminal of the battery module 102a. Therefore, no voltage is output from the battery module 102a to the output terminal. In this state, as shown in FIG. 3(a), the battery 10 (capacitor 14) of the battery module 102a is in a bypassed through state.

[0040] Furthermore, when the gate drive signal D1 is on (i.e., the first switch element 16 is off and the second switch element 18 is on), the capacitor 14 and the battery 10 are connected to the output terminal of the battery module 102a. Therefore, a voltage is output from the battery module 102a to the output terminal. In this state, as shown in FIG. 3(b), the voltage V mod is output to the output terminal.

[0041] In other words, when the gate drive signal is at a high (H) level, the capacitor 14 and battery 10 in the battery module 102 are connected in series (connected state) with the capacitors 14 and batteries 10 in the other battery modules 102, and when the gate drive signal is at a low (L) level, the capacitor 14 and battery 10 in the battery module 102 are disconnected from the capacitors 14 and batteries 10 in the other battery modules 102 and are in a through state.

[0042] Fig. 4 shows a control sequence in which a predetermined number of the battery modules 102a, 102b, ..., 102n are sequentially operated in a connected state to output power. As shown in Fig. 4, the battery modules 102a, 102b, ..., 102n are driven one after another from the upstream side to the downstream side with a certain delay time in response to the gate drive signal. In Fig. 4, a period E1 shows a state in which the first switch element 16 of the battery modules 102a, 102b, ..., 102n is turned off and the second switch element 18 is turned on, and the battery modules 102a, 102b, ..., 102n output voltage from the output terminals (connected state). Also, a period E2 shows a state in which the first switch element 16 of the battery modules 102a, 102b, ..., 102n is turned on and the second switch element 18 is turned off, and the battery modules 102a, 102b, ..., 102n do not output voltage from the output terminals (through state). In this manner, the battery modules 102a, 102b, . . . 102n are driven in sequence with a certain delay time therebetween.

[0043] The setting of the gate drive signal and the delay time will be described with reference to Fig. 4. The period T of the gate drive signal is set by adding up the delay times of the battery modules 102a, 102b, ... 102n. Therefore, the longer the delay time, the lower the frequency of the gate drive signal. Conversely, the shorter the delay time, the higher the frequency of the gate drive signal. How to set the frequency (switching frequency) will be described later.

[0044] For the sake of simplicity, the following description will be given of a case where no forced disconnection or forced connection is performed on each battery module 102. ONThe ratio is calculated by: output voltage of power supply system 100 / total voltage of battery modules 102a, 102b, ... 102n (if the battery voltages of each battery module 102 are equal, then the battery voltage of battery module 102 x number of battery modules). In other words, on-time ratio D = (output voltage of power supply system 100) / (battery voltage of battery module 102 x total number of battery modules 102). Strictly speaking, the on-time ratio deviates by the dead time dt, so it is preferable to correct the on-time ratio by feedback or feedforward, as is commonly done in chopper circuits.

[0045] As described above, when the battery voltages of the battery modules 102 are equal, the output voltage of the power supply system 100 is represented by a value obtained by multiplying the battery voltage of the battery module 102 by the number of battery modules 102 in a connected state. If the output voltage of the power supply system 100 is a value divisible by the battery voltage of one battery module 102, the moment a battery module 102 switches from a through state to a connected state, the other battery modules 102 switch from a connected state to a through state, so there is no fluctuation in the overall output voltage of the battery modules 102.

[0046] However, if the output voltage of the power supply system 100 is a value that is not divisible by the battery voltage of each battery module 102, the output voltage of the power supply system 100 (total output voltage) will fluctuate. However, the amplitude of the fluctuation at this time is the voltage of one battery module, and the period of this fluctuation is the period T of the gate drive signal divided by the total number of battery modules 102. By increasing the total number of battery modules 102, the period of the fluctuation can be shortened, and the parasitic inductance of the entire power supply system 100 can be made large, so that this voltage fluctuation is filtered and the output voltage of the power supply system 100 can be stabilized.

[0047] In addition, when in a connected state, a current flows through the second switch element 18 of each battery module 102, and as shown in Fig. 4, the current waveform J1 of the second switch element 18 becomes a square wave. In addition, because the battery 10 and the capacitor 14 form an RLC filter, a filtered and leveled current J2 flows through the battery 10 in each battery module 102. In this way, the current waveform is uniform in all of the battery modules 102a, 102b, ... 102n, and current can be output evenly from all of the battery modules 102a, 102b, ... 102n.

[0048] As described above, when controlling the power supply system 100, the gate drive signal output to the most upstream battery module 102a is output to the downstream battery module 102b with a fixed time delay, and this gate drive signal is further transmitted sequentially to the downstream battery modules 102 with a fixed time delay, so that the battery modules 102a, 102b, ... 102n sequentially output voltages with a fixed time delay. These voltages are then summed to output a voltage as the power supply system 100. In other words, the number of battery modules 102 that are simultaneously connected can be changed by adjusting the on-time ratio D (on-duty) of the gate drive signal, and the desired voltage can be output from the power supply system 100.

[0049] According to the power supply system 100, a DC-DC converter is not required, and the circuit configuration can be simplified. Also, a balance circuit that generates power loss is not required, and the efficiency of the power supply system 100 can be improved. Furthermore, since the voltage is output approximately evenly from the multiple battery modules 102a, 102b, ... 102n, driving is not concentrated on a specific battery module 102, and the internal resistance loss of the power supply system 100 can be reduced.

[0050] Furthermore, by adjusting the on-time ratio D, it is possible to generate a desired output voltage that is equal to or less than the sum of the battery voltages, thereby improving the versatility of the power supply system 100.

[0051] [Forced disconnection control] Next, the control for forcibly disconnecting the battery 10 in a battery module 102 selected from among the multiple battery modules 102 (102a, 102b, . . . 102n) will be described. The controller 104 outputs a forced disconnection signal to the signal processing circuit 22 of the battery module 102 to be forcibly disconnected. As a result, the signal processing circuit 22 outputs a low (L) level, a high (H) level is input to the gate terminal of the first switch element 16 by the NOT element, and a low (L) level is input to the gate terminal of the second switch element 18. Therefore, the first switch element 16 is always in the ON state, the second switch element 18 is always in the OFF state, and the battery 10 in the corresponding battery module 102 is in a forcibly disconnected state (pass-through state) regardless of the state of the gate drive signal. By using such forced disconnection control, it is possible to continue operation by disconnecting the battery 10 in a specific battery module 102 when the battery 10 in the specific battery module 102 fails.

[0052] The on-time ratio D in the case of forced disconnection is expressed as (output voltage of the power supply system 100) / (total voltage of the battery modules 102 excluding the battery module 102 in the forced disconnection state). When a failure occurs in the battery 10 in the battery modules 102a, 102b, . . . 102n or when measurement is performed by the impedance measuring device 30 described later, the target battery 10 is excluded and only the other battery modules 102 are used to reset the period T of the gate drive signal and the on-time ratio D, thereby obtaining a desired voltage. That is, even if the battery 10 in the battery modules 102a, 102b, . . . 102n is forcibly disconnected, the output of the desired voltage can be continued. In addition, it can be used for control to suppress imbalance in SOC of the batteries 10 in the battery modules 102 when there is variation in the battery capacity of each battery module 102.

[0053] For example, when the power supply system 100 is in a power running state, by forcibly disconnecting the batteries 10 in the battery modules 102 with a relatively low SOC among the batteries 10 in the battery modules 102 included in the power supply system 100, the power consumption (accumulated amount of discharge current per unit time) of the forcibly disconnected batteries 10 can be reduced, and the imbalance in the SOC of the batteries 10 in the battery modules 102 can be eliminated. As a result, the SOC of the batteries 10 in the battery modules 102 can be brought closer to the SOC control target value. Also, the charging energy of the batteries 10 in each battery module 102 can be used up efficiently.

[0054] Also, when the battery module 102 is in a regenerative state, not in a power running state, a control for eliminating the SOC imbalance of the batteries 10 in the battery module 102 can be performed. In this case, the battery module 102 with a relatively high SOC is controlled to be forcibly disconnected, and the battery module 102 with a relatively low SOC is preferentially regenerated to eliminate the SOC imbalance of the batteries 10 in the battery module 102. That is, the power supply (accumulated charging current per unit time) to the battery module 102 with a relatively high SOC among the batteries 10 in the battery module 102 is reduced, and the SOC imbalance of the batteries 10 in the battery module 102 can be eliminated. As a result, the SOC of the batteries 10 in the battery module 102 can be brought closer to the SOC control target value. Also, the batteries 10 in all the battery modules 102 included in the power supply system 100 can be charged in a well-balanced manner. Furthermore, the battery module 102 with a small charging capacity can be prevented from being overcharged.

[0055] Furthermore, the forced disconnection control can be used for control to suppress deterioration of the battery 10 in the battery module 102 in the power supply system 100. That is, when metal deposition in the battery 10 becomes noticeable or an abnormality such as damage occurs in the battery 10, the battery 10 can be forced to be disconnected to suppress metal deposition or slow down the progression of the abnormality.

[0056] [Forced connection control] Next, a description will be given of the control for forcibly connecting a selected one of the batteries 10 in the multiple battery modules 102 (102a, 102b, ... 102n). The controller 104 outputs a forcible connection signal to the signal processing circuit 22 of the battery module 102 to be forcibly connected.

[0057] As a result, a high (H) level is output from the signal processing circuit 22, a low (L) level is input to the gate terminal of the first switch element 16 by the NOT element, and a high (H) level is input to the gate terminal of the second switch element 18. Therefore, the first switch element 16 is always in the OFF state, the second switch element 18 is always in the ON state, and the batteries 10 in the battery module 102 are forcibly connected in series regardless of the state of the gate drive signal. Such forced connection control can be used for control to suppress imbalance in SOC of the batteries 10 in the battery module 102 in the power supply system 100.

[0058] For example, when the power supply system 100 is in a regenerative state, by forcibly connecting the batteries 10 in the battery modules 102 with a relatively low SOC among the batteries 10 in the battery modules 102 included in the power supply system 100, charging the forcibly connected batteries 10 with regenerative power is preferentially performed, the amount of accumulated charging current per unit time increases, and the imbalance in the SOC of the batteries 10 in the battery modules 102 can be eliminated. As a result, the SOC of the batteries 10 in the battery modules 102 can be brought closer to the SOC control target value. Also, the batteries 10 in all the battery modules 102 included in the power supply system 100 can be charged in a balanced manner.

[0059] Also, when the power supply system 100 is in a powering state rather than a regenerative state, it is possible to perform control to eliminate the SOC imbalance of the batteries 10 in the battery modules 102 included in the power supply system 100. In this case, control is performed to forcibly connect the batteries 10 in the battery modules 102 with a relatively high SOC, and the SOC imbalance is eliminated by increasing the power consumption of the batteries 10 in the battery modules 102 with a relatively high SOC. That is, the power supply (integrated amount of discharge current per unit time) from the batteries 10 in the battery modules 102 with a relatively high SOC among the batteries 10 in the battery modules 102 increases, and the SOC imbalance of the batteries 10 in the battery modules 102 can be eliminated. As a result, the SOC of the batteries 10 in the battery modules 102 can be brought closer to the SOC control target value. Also, it is possible to efficiently use up the charging energy of the batteries 10 in all the battery modules 102 included in the power supply system 100.

[0060] [Impedance measurement] In the power supply system 100, an impedance measuring device 30 is provided for each battery module 102. The impedance measuring device 30 is used to measure the characteristics of the batteries 10 included in each battery module 102.

[0061] 5, an impedance measuring device 30 according to an embodiment of the present invention includes a resonant circuit 32, a differential single conversion circuit 34, and a peak hold circuit 36. The impedance measuring device 30 is connected to the battery 10 (battery BAT), and acquires, holds, and outputs the peak voltage value of any maximum or minimum peak contained in a signal having a damped oscillation waveform generated by the resonant circuit 32.

[0062] The resonant circuit 32 is connected to the battery BAT, and converts the voltage of the battery BAT into a resonant voltage having a damped oscillation waveform and outputs it by controlling the timing of opening and closing the switch SWres. The resonant circuit 32 includes resonant inductors Lres and Lsec, a resonant capacitance Cres, and a resonant resistor Rres. The resonant inductor Lres and the resonant inductor Lsec have a transformer structure with a mutual inductor M.

[0063] The differential to single conversion circuit 34 differentially amplifies the resonant voltage Vres generated across the resonant inductor Lsec and outputs the amplified voltage to the peak hold circuit 36 ​​.

[0064] The peak hold circuit 36 ​​is a non-inverting type peak hold circuit including a comparator CP. The output voltage value (peak hold voltage value) Vpho acquired and held by the peak hold circuit 36 ​​is input to the inverting input terminal of the comparator CP, and the resonant voltage Vres output from the differential single conversion circuit 34 is input to the non-inverting input terminal of the comparator CP. The comparator CP generates a pulse signal Vco when the resonant voltage Vres is higher than the output voltage value Vpho, and turns on the switch SWch when the switch SWsp is in the on state. On the other hand, when the resonant voltage Vres is lower than the output voltage value Vpho, the comparator CP does not generate a pulse signal, and turns off the switch SWch even if the switch SWsp is in the on state. Note that when the switch SWsp is in the off state, the switch SWch is turned off regardless of whether the pulse signal Vco is output from the comparator CP. When the switch SWch is turned on, a current flows from a charging unit (voltage source) that supplies power to the charge capacitance Cc through a resistor Rc to the charge capacitance Cc, and charge is accumulated in the charge capacitance Cc, causing the terminal voltage of the charge capacitance Cc to rise. The terminal voltage of the charge capacitance Cc is output as the output voltage value Vpho of the peak hold circuit 36. Note that in order to discharge and reset the charge stored in the charge capacitance Cc, the switch SWdch is turned on.

[0065] Here, the time constant of the resistor Rc and the charge capacitance Cc allows the terminal voltage of the charge capacitance Cc to reach the peak voltage value of the resonant voltage Vres input in one charge. However, when the frequency of the resonant voltage Vres is high, the error between the resonant voltage Vres and the output voltage value Vpho of the peak hold circuit 36 ​​increases due to the effects of switching delay and feedback delay. Therefore, it is preferable to set the time constant of the resistor Rc and the charge capacitance Cc to a value that prevents the terminal voltage of the charge capacitance Cc from reaching the peak voltage value of the resonant voltage Vres in one operation. By providing the resistor Rc, the lower the terminal voltage of the charge capacitance Cc, the faster the charge of the electric charge, and the higher the terminal voltage, the slower the charge of the electric charge, making it possible to acquire and hold the peak voltage value of each peak of the resonant voltage Vres with high accuracy.

[0066] Fig. 6 is a flowchart showing a peak hold process for acquiring and holding a peak voltage value of the resonant voltage Vres having a damped oscillation waveform. Also, Fig. 7 shows a sequence of the peak hold process by the impedance measuring device 30. Fig. 7 shows a sequence when the second peak of the resonant voltage Vres having a damped oscillation waveform is set as a target peak and its peak voltage value is peak held.

[0067] In step S10, the switch SWdch is turned off to change the charge capacitance Cc from a reset state in which the charge capacitance Cc is discharged to a state in which the charge capacitance Cc can store electric charge. At this time, the count value count of the number of times the process is repeated is also reset to 0.

[0068] In step S12, the switch SWres of the resonant circuit 32 is turned from off to on. This causes the resonant voltage Vres having a damped oscillation waveform to be output from the resonant circuit 32. At this time, the count value count of the number of times the process is repeated is incremented by 1. FIG. 8 shows an example of the change over time of the damped oscillation waveform of the resonant voltage Vres. As time passes on the horizontal axis, the resonant voltage Vres shows a peak value Vres(t1) at time t1, a peak value Vres(t2) at time t2, and so on until the elapsed time tn, at which point the resonant voltage Vres shows a peak value Vres(tn).

[0069] In step S14, a delay process is performed for a predetermined delay time. The delay time here is set so as to delay from the time when the switch SWres is turned on to a time after the peak immediately before the target peak to be peak-held in the resonant voltage Vres having a damped oscillation waveform and before the target peak. In particular, it is preferable to set the delay time so that the switch SWsp is turned on from off at a position of 1 / 4 wavelength to 3 / 4 wavelength of the target peak. For example, in FIG. 8, when the second peak of the resonant voltage Vres having a damped oscillation waveform is set as the target peak for peak holding, the delay time is set to a time after the time t1 of the first peak immediately before the target peak and before the time t2 of the second peak which is the target peak, based on the time when the switch SWres is turned on to start generating the resonant voltage Vres having a damped oscillation waveform.

[0070] In step S16, the switch SWsp is turned on from off, which causes the switch SWch to be turned on by the pulse signal Vco generated in the comparator CP when the output voltage value Vpho is greater than the resonant voltage Vres.

[0071] The comparator CP compares the output voltage Vpho input to the inverting input terminal with the resonant voltage Vres input to the non-inverting input terminal, and generates a pulse signal Vco to turn on the switch SWch when the resonant voltage Vres is higher than the output voltage Vpho. In this state, a current flows through the charge capacitance Cc via the resistor Rc, charge is accumulated in the charge capacitance Cc, and the terminal voltage of the charge capacitance Cc and further the output voltage Vpho increase.

[0072] 7, the comparator CP outputs a pulse signal Vco when the output voltage value Vpho exceeds the resonant voltage Vres, and therefore, if the switch SWsp is in the on state, charging of the charge capacitance Cc is repeated in accordance with each peak of the damped oscillation waveform of the resonant voltage Vres until the output voltage value Vpho exceeds the resonant voltage Vres. On the other hand, when the resonant voltage Vres becomes higher than the output voltage value Vpho, the comparator CP does not generate a pulse signal, and charging of the charge capacitance Cc ends.

[0073] In step S18, a delay process is performed for a predetermined delay time. The delay time is set so as to delay from the time when the switch SWres is turned on to a time after the target peak to be held in the resonant voltage Vres having a damped oscillation waveform and before the time of occurrence of the next resonant voltage Vres. For example, in FIG. 8, if the second peak of the resonant voltage Vres having a damped oscillation waveform is set as the target peak to be held, the delay time is set to a time after the time t2 of the second peak, which is the target peak, based on the time when the switch SWres is turned on and the resonant voltage Vres having a damped oscillation waveform starts to be generated, and before the time of occurrence of the next resonant voltage Vres.

[0074] In step S20, the switch SWsp is turned from on to off, which stops the pulse signal Vco of the output of the comparator CP from being transmitted to the switch SWch, and turns the switch SWch off regardless of the level relationship between the output voltage value Vpho and the resonant voltage Vres.

[0075] In step S22, the switch SWres of the resonant circuit 32 is turned from on to off, whereby the output of the resonant voltage Vres having a damped oscillation waveform from the resonant circuit 32 is stopped.

[0076] In step S24, a delay process is performed for a predetermined delay time. The delay time is a waiting time until the next resonant voltage Vres having a damped oscillation waveform is generated, and it is preferable to set the delay time to a time during which the previous resonant voltage Vres is damped to a degree that does not affect the next resonant voltage Vres having a damped oscillation waveform.

[0077] In step S26, it is determined whether the count value "count" has reached the maximum count "Cntmax". If the count value "count" has reached the maximum count "Cntmax", the process proceeds to step S28. If not, the process returns to step S12 to repeat the peak hold process for the same peak. The maximum count "Cntmax" may be preset so that the process is repeated to a degree that ensures that the peak hold process is performed.

[0078] By repeating the processes from step S12 to step S26, the peak hold process is performed as shown by the change in the output voltage value Vpho at the bottom of FIG. 7. In the first resonant voltage Vres, the charge capacitance Cc is charged with electric charge due to the damped oscillating second, third, and fourth peaks, and the output voltage value Vpho gradually rises until it reaches a voltage value higher than the fifth peak. In the second resonant voltage Vres, the charge capacitance Cc is further charged with electric charge due to the damped oscillating second and third peaks, and the output voltage value Vpho rises further until it reaches a voltage value higher than the fourth peak. In the third resonant voltage Vres, the charge capacitance Cc is further charged with electric charge due to the damped oscillating second and third peaks, and the output voltage value Vpho rises further until it reaches a voltage value higher than the third peak. At the fourth to sixth resonant voltages Vres, the damped oscillating second peak further charges the charge capacitance Cc, and as a result, the output voltage value Vpho rises until it finally reaches a voltage value that matches the peak voltage of the second peak, and the peak voltage value of the second peak, which is the target peak, is acquired and held as the output voltage value Vpho.

[0079] In this manner, in the impedance measuring device 30 of this embodiment, the charge capacitance Cc is charged not only by the target peak that is the target of the peak hold process, but also by other peaks included in the resonant voltage Vres having an oscillation damping waveform. Therefore, the output voltage value Vpho can be increased more quickly to the peak voltage value of the target peak by using the other peaks.

[0080] In step S28, the output voltage value Vpho is read out. The controller 104 reads out the output voltage value Vpho acquired and held in steps S10 to S26.

[0081] In step S30, it is determined whether or not to perform peak hold for the next peak. If the peak hold process is to be performed for the next peak, the process proceeds to step S34, and if the peak hold process is to be ended, the process proceeds to step S32.

[0082] In step S32, the switch SWdch is turned on, the charge capacitance Cc is discharged to a reset state, and the peak hold process is terminated. In step S34, the next peak is set as the target peak, and the peak hold process for the target peak is started. Here, it is preferable to turn on the switch SWdch, discharge the charge capacitance Cc to a reset state, and then return the switch SWdch to an off state. In step S36, the count value count is reset to 0, and the process is repeated from step S12.

[0083] In addition, by changing the target peak from a later peak having a lower peak voltage value to a previous peak having a higher peak voltage value in the resonant voltage Vres having a damped oscillation waveform, it becomes unnecessary to acquire and hold the peak voltage value of each peak as the output voltage value Vpho, and then turn on the switch SWdch to discharge the charge capacitance Cc. In other words, by acquiring, holding, and reading out the later peak having a lower peak voltage value as the output voltage value Vpho, and setting the previous peak having a higher peak voltage value as the next target peak, it is possible to further charge the charge capacitance Cc so that it matches the peak voltage value of the next target peak, and acquire and hold it as the output voltage value Vpho, without discharging the charge that had been stored up to that point.

[0084] In the impedance measuring device 30, by using an integrating type in which electric charge is charged to the charge capacitance Cc multiple times, the amount of tracking per time becomes small, but the accuracy of tracking the peak voltage value becomes high. Therefore, even if the resonant voltage Vres has a high-frequency damped oscillation waveform exceeding 10 kHz, which is difficult to track the peak by a single peak hold process, the peak voltage value can be acquired and held as the output voltage value Vpho with high accuracy.

[0085] 9 to 12 show examples of the peak hold circuit 36. FIG. 9 shows a non-inverting peak hold circuit including a comparator CP applied to the impedance measuring device 30 shown in FIG. 5. The non-inverting peak hold circuit is used to obtain the peak voltage value of the positive peak (maximum peak) of the resonance voltage Vres. FIG. 10 shows an inverting peak hold circuit including a comparator CP. The inverting peak hold circuit is used to obtain the peak voltage value of the negative peak (minimum peak) of the resonance voltage Vres. FIG. 11 shows a non-inverting peak hold circuit in which the voltage source via the resistor Rc is changed to a constant current source CS in the charge supply circuit to the charge capacitance Cc. FIG. 12 shows a non-inverting peak hold circuit in which the resistor Rc is changed to a variable resistor in the charge supply circuit to the charge capacitance Cc. By making the resistor Rc a variable resistor, the time constant of the charge to the charge capacitance Cc can be made variable, so that the peak voltage value can be obtained more quickly and with higher accuracy. The configurations of FIGS. 11 and 12 can also be applied to an inverting peak hold circuit including a comparator CP.

[0086] [How to calculate battery impedance] A method for calculating the internal impedance of the battery BAT will be described below.

[0087] The resonant voltage Vres(t) is expressed by the formulas (1) to (6), where Vbat is the voltage of the battery BAT, Cbat is the internal capacitance, Rbat is the internal inductance, and Cres is the internal capacitance of the resonant circuit 32, Lres is the resonant inductance (primary side) and Lsec is the internal inductance (secondary side) of the resonant circuit 32, M is the mutual inductance between the resonant inductance Lres (primary side) and the resonant inductance Lsec (secondary side), Rres is the resonant resistance, ω0 is the resonant angular frequency, Ls is the series combined inductance of the resonant inductance Lres (primary side) and the internal inductance Lbat, Cs is the series combined capacitance of the resonant capacitance Cres and the internal capacitance Cbat, tn is the elapsed time from the resonance start time, α is the attenuation rate of the damped resonant voltage, and β is the phase difference of the damped resonant voltage.

number

number

number

number

number

number

[0088] The resonant voltage V res (t n ) is expressed by equation (7).

number

[0089] For any n = n1, n2 (n1>n2), the attenuation rate α is expressed by equation (8).

number

[0090] The resonant resistance R of the resonant circuit 32 res is the internal resistance R of the battery BAT bat Sufficiently larger than (R res >>R bat ), the resonance angular frequency ω0 is expressed by equation (9).

number

[0091] The real impedance R of the battery BAT bat , imaginary impedance L bat can be calculated using formulas (10) and (11). However, the internal capacity C of the battery BAT bat is so large that it can be ignored.

number

number

[0092] As described above, the real impedance Rbat and the imaginary impedance Lbat of the battery BAT can be calculated based on the peak voltage value of the maximum peak or minimum peak of the resonance voltage Vres(t) acquired by the impedance measuring device 30.

[0093] [Method for detecting the amount of lithium deposition inside a battery] Figure 13 shows the change in the real impedance (1 MHz) of the battery BAT versus the amount of lithium (Li) deposited when the battery BAT is a lithium-ion battery. The figure shows the results of a degradation test in which lithium (Li) was deposited by repeatedly charging a commercially available cylindrical lithium-ion battery at a high rate at low temperature.

[0094] As shown in FIG. 13, the amount of lithium (Li) deposited in the battery BAT shows a linear relationship with the change in the real impedance of the battery BAT, and the amount of lithium (Li) deposited in the battery BAT can be estimated by the formula: Amount of Lithium Deposition = Amount of Change in the Real Impedance of the Battery BAT x Coefficient.

[0095] [Method of estimating the internal temperature of a battery] 14 shows the change in the real impedance and imaginary impedance (1 MHz) of the battery BAT with respect to the internal temperature of the battery BAT. The change in the real impedance and imaginary impedance of the battery BAT shows a linear relationship with the internal temperature of the battery BAT, and the internal temperature of the battery BAT can be estimated by the formula: internal temperature of the battery BAT = coefficient x change in impedance + reference temperature.

[0096] [Three-phase AC power supply system] 15 shows the configuration of a three-phase AC power supply system 200 that utilizes the power supply system 100. The three-phase AC power supply system 200 is configured by combining three sets of power supply systems 100.

[0097] The three power supply systems 100 (string a, string b, string c) are connected in a Y-connection so that the output voltage polarity of each string is the same at the neutral point. In Fig. 15, the negative pole sides of the three power supply systems 100 (string a, string b, string c) are connected to the neutral point, but the positive pole sides of all the strings may be connected to the neutral point.

[0098] In the three-phase AC power supply system 200, the number of connections of the batteries 10 in the battery module 102 in each of the three power supply systems 100 of the strings a to c is controlled to be changed over time, thereby controlling the AC voltage E a ,E b ,E c That is, in each of the power supply systems 100, the on-time ratio D (on-duty) of the gate drive signal is independently adjusted to change the number of battery modules 102 that are simultaneously connected, and the output voltage is changed over time to output AC power.

[0099] However, since each of the power supply systems 100 can only generate a voltage of 0 V or higher, as shown in FIG. a ,E b ,E c The two amplifiers have an offset of 120° and generate voltages with a phase difference of 120°.

[0100] In addition, by generating AC voltages with the same offset voltage in each of strings a to c, the line voltage V uv ,V vw ,V wuIt is possible to generate positive and negative AC voltages with an average voltage of 0 V. As a result, the battery module 102 included in the power supply system 100 does not need to use a full-bridge circuit using four switches, but uses a half-bridge circuit, thereby reducing manufacturing costs.

[0101] The output ends of the strings a to c are connected to a filter 202. The filter 202 includes an interconnection reactor L m (L mu ,L mv ,L mw ), filter capacitor C f (C fu ,C fv ,C fw ) and filter reactor L f (L fu ,L fv ,L fw ) can be included. The filter 202 is provided for each phase of the strings a to c. The filter capacitor is connected to the neutral point. The output of the filter 202 is connected to the secondary side of the transformer 204. A relay may be provided between the filter 202 and the transformer 204.

[0102] In addition, a current sensor (I a , I b , I c ) may be provided. Current sensors may be provided for only two phases, and the current for the remaining phase may be calculated from the measured currents of the two phases. For example, the current I a and b-phase current I b When measuring the c-phase current I c I c =-I a -I b It can be found by:

[0103] In addition, a voltage sensor (V u , V v , V w By measuring the filter capacitor voltage, the voltage of each phase of the system can be measured.

[0104] [Power supply system control method] In the power supply system 100 of this embodiment, the voltage, temperature, impedance, SOC, and other parameters of the battery 10 in each battery module 102 are measured by the impedance measuring device 30. The battery module 102 can be controlled according to the resistance deterioration (SOH), capacity deterioration (SOH), and lithium deposition amount (SOS).

[0105] The control of the power supply system 100 may be, for example, any of constant current charge / discharge control (CC charge / discharge control), constant voltage charge / discharge control (CV charge / discharge control), and forced cutoff control. The constant current charge / discharge control (CC charge / discharge control) adjusts the on-time ratio D in the above-mentioned normal control to control the current output from each battery module 102 to a constant value. The constant voltage charge / discharge control (CV charge / discharge control) adjusts the on-time ratio D in the above-mentioned normal control to control the voltage output from each battery module 102 to a constant value.

[0106] When control is performed according to the voltage of the battery 10 in the battery module 102, it is preferable to perform constant current charge / discharge control (CC charge / discharge control) or constant voltage charge / discharge control (CV charge / discharge control) by applying the above-mentioned normal control, forced disconnection control, and forced connection control, and control the output voltage of each battery module 102 to a desired value.

[0107] It is also possible to estimate the temperature of the batteries 10 in the battery module 102 based on the measurement by the impedance measuring device 30, and perform control according to the temperature. When performing control according to the temperature of the batteries 10, for example, either constant current charge / discharge control (CC charge / discharge control) or forced cutoff control can be applied.

[0108] Control can also be performed according to the impedance of the battery 10 in the battery module 102 based on measurement by the impedance measuring device 30. When control is performed according to the impedance of the battery 10, for example, constant current charge / discharge control (CC charge / discharge control) can be applied. Control can also be performed according to the resistance degradation or capacity degradation (SOH) of the battery module 102 based on measurement by the impedance measuring device 30. When control is performed according to the resistance degradation (SOH) or capacity degradation (SOC) of the battery 10, for example, constant current charge / discharge control (CC charge / discharge control) can be applied.

[0109] Furthermore, when metal such as lithium is deposited on the battery 10 of the battery module 102 (SOS) or when the battery 10 is damaged or otherwise defective (hereinafter referred to as an abnormal state), for example, either constant current charge / discharge control (CC charge / discharge control) or forced cutoff control can be applied. The abnormal state of the battery 10 is not limited to when metal such as lithium is deposited (SOS) or when the battery 10 is damaged, but may be any state of the battery 10 that adversely affects the power supply system 100. For example, when the impedance measuring device 30 detects that the battery 10 is in an abnormal state, constant current charge / discharge control (CC charge / discharge control) can be applied to the battery module 102 including the battery 10, and the charge / discharge amount of the battery 10 can be suppressed compared to normal control, thereby slowing down the progression of metal deposition or damage. Furthermore, for example, if the impedance measuring device 30 detects that the battery 10 is in an abnormal state, forced disconnection control can be applied to the battery module 102 including the battery 10 to stop charging and discharging the battery 10, thereby slowing down the progression of metal deposition and damage, and avoiding adverse effects of the battery 10 on the power supply system 100.

[0110] As described above, each battery module 102 can be controlled according to the battery voltage, battery impedance, battery resistance degradation, capacity degradation, battery capacity, and abnormal states such as metal deposition or damage of the battery. This makes it possible to adjust the charge amount of the battery 10 included in each battery module 102 and limit the output / input of the battery 10. In addition, by forcibly disconnecting the battery module 102 including a defective battery 10, the battery 10 can be replaced without significantly affecting the operation of the power supply system 100.

[0111] [Improved accuracy of battery status measurement] Hereinafter, a method for improving the measurement accuracy of the battery state of the battery 10 by the impedance measuring device 30 by controlling the temperature of the battery 10 included in the battery module 102 will be described. That is, by controlling the temperature of the battery 10, which is the subject of battery state measurement by the impedance measuring device 30, to a desired value, the effect of the temperature of the battery 10 on the measurement of the battery state is kept constant, thereby improving the accuracy of the measurement of the battery state of the battery 10.

[0112] 17 shows a flowchart of the battery state measuring method of the battery 10 in this embodiment. Specifically, the temperature of the battery 10 is controlled by utilizing reactive power in the three-phase AC power supply system 200 shown in FIG.

[0113] In step S40, a battery module 102 is determined as a measurement target of the impedance measuring device 30. One of the battery modules 102 included in the three-phase AC power supply system 200 is determined as the measurement target.

[0114] In step S42, control is performed so that only reactive power is output from the battery module 102 determined as the measurement target. In the power supply system 100, the timing of connecting the battery module 102 determined as the measurement target to the load is controlled so that only reactive power is output from the battery module 102.

[0115] FIG. 18 is a diagram for explaining reactive power output from an AC power supply. FIG. 18 is an equivalent circuit diagram showing each phase of a three-phase AC power supply system 200 as a single-phase AC power supply. The active power P output from the AC power supply is calculated by P=VIcosθ according to the power factor cosθ determined by the phase difference θ between the output voltage V and the output current I. The active power P contributes to the SOC of the battery 10. On the other hand, the reactive power Q output from the AC power supply is calculated by Q=VIsinθ. The reactive power Q is based on the circulating current in the AC circuit and does not contribute to the SOC of the battery 10. By utilizing the reactive power Q, it is possible to flow a current to the battery 10 while maintaining the SOC of the battery 10 constant.

[0116] Therefore, the control controller 104 outputs a gate drive signal D1 so as to connect the battery module 102 determined as the measurement target to the load only when the active power P becomes 0, i.e., when the output voltage V becomes 0. Alternatively, the control controller 104 may output a forced connection signal so as to connect the battery module 102 determined as the measurement target to the load only when the active power P becomes 0, i.e., when the output voltage V becomes 0, and may output a forced disconnection signal so as not to connect the battery module 102 determined as the measurement target to the load at other times.

[0117] In this way, by connecting the battery module 102 determined as the measurement target to the load only when the output voltage V becomes 0, it is possible to pass a current through the battery 10 while maintaining the SOC of the battery 10 included in the battery module 102 constant. At this time, a conduction loss occurs due to the internal resistance of the battery 10, and the temperature of the battery 10 rises.

[0118] By utilizing this phenomenon, the temperature of the battery 10 can be increased to a desired value and maintained at that temperature. For example, the internal temperature of the battery 10 included in each battery module 102 is estimated based on measurements by the impedance measuring device 30 provided in each battery module 102. Then, the temperature increase by the reactive power Q can be continued until the estimated temperature reaches a desired value, and when the battery 10 reaches the desired temperature, the temperature increase by the reactive power Q can be intermittently executed so as to maintain the temperature. Also, for example, a temperature sensor such as a thermocouple can be provided in the battery 10 of each battery module 102, and the temperature increase by the reactive power Q can be continued until the temperature measured by the temperature sensor reaches a desired value, and when the battery 10 reaches the desired temperature, the temperature increase by the reactive power Q can be intermittently executed so as to maintain the temperature.

[0119] In step S44, it is determined whether the temperature of the battery 10 included in the battery module 102 determined as the measurement target has saturated. If the temperature of the battery 10 has reached and is being maintained at a desired temperature, the process proceeds to step S46, and if not, the process returns to step S42 to continue raising the temperature of the battery 10.

[0120] In this embodiment, it is determined whether the temperature of the battery 10 included in the battery module 102 determined as the measurement target has reached and been maintained at a desired temperature, but the process may proceed to step S46 after the temperature of the battery 10 is increased by the reactive power Q for a certain period of time.

[0121] In step S46, the battery state of the battery 10 included in the battery module 102 determined as the measurement target is measured. Based on the above-described battery state measurement method, the battery state of the battery 10 is measured by the impedance measuring device 30 provided in the battery module 102 determined as the measurement target. At this time, the battery 10 is at a desired temperature, so that the accuracy of the impedance measurement and state measurement of the battery 10 by the impedance measuring device 30 can be improved.

[0122] In step S48, a reset process is performed on the battery module 102 determined as the measurement target. In this step, the battery module 102 determined as the measurement target in step S40 is removed from the measurement targets, and is treated in the same manner as the other battery modules 102.

[0123] As described above, according to this embodiment, the accuracy of measuring the state of the battery 10 in the power supply system 100, such as the impedance, can be improved.

[0124] [Configuration of the invention] [Configuration 1] A power supply system that uses a battery module group including a plurality of battery modules each having a battery, and is capable of serially connecting and disconnecting the batteries in the plurality of battery modules to each other based on a gate drive signal from a control controller, Each of the battery modules is provided with an impedance measuring device; A power supply system characterized in that the battery in the battery module that has been separated from the series connection is treated as a measurement target, the battery state of the measurement target battery is measured by the impedance measuring device, and control of the measurement target battery is performed in accordance with the battery state. [Configuration 2] The power supply system according to configuration 1, A power supply system comprising: a power supply unit for controlling a current flowing through each of said batteries to be measured, said power supply unit being operable to control a progress of said abnormal state when said battery state is abnormal; [Configuration 3] The power supply system according to configuration 1, A power supply system capable of forcibly disconnecting the battery being measured from the series connection without shutting down the power supply system when the battery state is abnormal. [Configuration 4] The power supply system according to configuration 2 or 3, The power supply system, wherein the abnormal state is a state in which metal has precipitated in the battery to be measured, or a state in which the battery to be measured has been damaged. [Configuration 5] The power supply system according to any one of configurations 1 to 4, A power supply system, wherein the impedance measuring device uses a resonant circuit to cause an AC current to undergo damped oscillation and measures the impedance according to a damping rate of the damped oscillation. [Configuration 6] 6. The power supply system according to claim 5, the impedance measuring device includes a peak hold circuit for acquiring a peak value of any maximum peak or minimum peak included in the damped oscillation, A power supply system characterized in that a maximum or minimum peak for which the peak value is to be obtained is set as a target peak, and a process of starting to hold the value of the damped oscillation at a time before the target peak and stopping to hold the value of the damped oscillation at a time after the target peak is repeated for a plurality of the damped oscillations. [Configuration 7] The power supply system according to configuration 5 or 6, The power supply system according to claim 1, wherein the impedance measuring device estimates an amount of metal deposition in the battery from an amount of decrease in the measured real impedance. [Configuration 8] The power supply system according to configuration 5 or 6, A power supply system, wherein the impedance measuring device estimates an internal temperature of the battery from a decrease in at least one of the measured real impedance and imaginary impedance. [Configuration 9] The power supply system according to any one of configurations 1 to 8, A plurality of the battery modules are used to provide AC output; A power supply system comprising: a battery control section for controlling a temperature of each of the batteries by controlling reactive power of the batteries individually. [Explanation of symbols]

[0125] 10 battery, 12 choke coil, 14 capacitor, 20 delay circuit, 22 signal processing circuit, 24 OR element, 30 impedance measuring device, 32 resonant circuit, 34 differential single conversion circuit, 36 peak hold circuit, 100 power supply system, 102 battery module, 104 control controller, 200 three-phase AC power supply system, 202 filter, 204 transformer.

Claims

1. A power supply system that uses a battery module group including a plurality of battery modules each having a battery, and is capable of serially connecting and disconnecting the batteries in the plurality of battery modules to each other based on a gate drive signal from a control controller, Each of the battery modules is provided with an impedance measuring device; A power supply system characterized in that the battery in the battery module that has been separated from the series connection is treated as a measurement target, the battery state of the measurement target battery is measured by the impedance measuring device, and control of the measurement target battery is performed in accordance with the battery state.

2. 2. The power supply system of claim 1, A power supply system comprising: a power supply unit for controlling a current flowing through each of said batteries to be measured, said power supply unit being operable to control a progress of said abnormal state when said battery state is abnormal;

3. 2. The power supply system of claim 1, A power supply system capable of forcibly disconnecting the battery being measured from the series connection without shutting down the power supply system when the battery state is abnormal.

4. 4. The power supply system according to claim 2 or 3, The power supply system, wherein the abnormal state is a state in which metal has precipitated in the battery to be measured, or a state in which the battery to be measured has been damaged.

5. 2. The power supply system of claim 1, A power supply system, wherein the impedance measuring device uses a resonant circuit to cause an AC current to undergo damped oscillation and measures the impedance according to a damping rate of the damped oscillation.

6. 6. The power supply system according to claim 5, the impedance measuring device includes a peak hold circuit for acquiring a peak value of any maximum peak or minimum peak included in the damped oscillation, A power supply system characterized in that a maximum or minimum peak for which the peak value is to be obtained is set as a target peak, and a process of starting to hold the value of the damped oscillation at a time before the target peak and stopping to hold the value of the damped oscillation at a time after the target peak is repeated for a plurality of the damped oscillations.

7. 7. The power supply system according to claim 5, The power supply system according to claim 1, wherein the impedance measuring device estimates an amount of metal deposition in the battery from an amount of decrease in the measured real impedance.

8. 7. The power supply system according to claim 5, A power supply system, wherein the impedance measuring device estimates an internal temperature of the battery from a decrease in at least one of a measured real impedance part and an imaginary impedance part.

9. 2. The power supply system of claim 1, A plurality of the battery modules are used to provide AC output; A power supply system comprising: a battery control section for controlling a temperature of each of the batteries by controlling reactive power of the batteries individually.

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