Battery status measurement device and power supply system using the same

Abstract

To provide a power supply system capable of diagnosing health status (SOH) and safety status (SOS) during operation. [Solution] A power supply system 100 is provided that uses a group of battery modules 102 each having a battery 10, and is capable of connecting and disconnecting the batteries 10 in the multiple battery modules 102 in series based on a gate drive signal from a control controller 104, and is equipped with an impedance measuring device 30 for measuring the impedance of the battery modules 102, and during system operation, the impedance measuring device 30 measures the battery state of the battery 10 to be measured, and the power supply system 100 is capable of classifying the batteries 10 according to their state.

Description

[Technical Field]

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

[0002] Power supply systems that use multiple battery modules to stably supply power to a load are widely used. In such power supply systems, it is important to accurately determine battery degradation and to be able to continuously supply stable power.

[0003] A battery degradation determination system is disclosed (Patent Document 1) that includes a management server that records battery element identification information and usage history information in association, and a degradation determination unit that measures a first electrical characteristic of the battery element during charging or discharging, determines a first degradation level based on the measurement results of the first electrical characteristic and the usage history information, and records diagnostic information including the first degradation level in association with the identification information on the management server. The system measures a second electrical characteristic of the battery element during charging or discharging after a predetermined period has elapsed, updates the usage history information, determines a second degradation level based on the measurement results of the second electrical characteristic and the usage history information, updates the diagnostic information by adding the second degradation level, and notifies the replacement of the battery element based on the second degradation level. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2023-076467 [Overview of the project] [Problems that the invention aims to solve]

[0005] By the way, it takes cost and time to diagnose the state of a battery with unknown state. Also, although technologies for diagnosis during system operation have been developed, past usage history is required and only the diagnosis of the state of health (SOH) can be performed. In the case of lithium-ion batteries, there is a risk that the soundness of the battery may deteriorate due to lithium (Li) metal precipitation, and it is also important to evaluate the state of safety (SOS) of the battery.

[0006] One of the problems of the present invention is to provide a technology that can diagnose the state of health (SOH) and the state of safety (SOS) during the operation of a power supply system and can classify the state of the battery.

Means for Solving the Problems

[0007] One aspect of the present invention uses a battery module group including a plurality of battery modules having batteries, and is capable of serially connecting and disconnecting the batteries in the plurality of battery modules based on a gate drive signal from a control controller. A power supply system, comprising an impedance measuring device that measures the impedance of the battery module, measuring the battery state of the battery to be measured by the impedance measuring device during system operation, and being able to classify the battery according to the battery state. It is a power supply system characterized by this.

[0008] Here, it is preferable that the impedance measuring device uses a resonant circuit to attenuate and oscillate an alternating current, and measures the impedance according to the attenuation rate of the damped oscillation.

[0009] Also, the impedance measuring device includes a peak hold circuit that acquires the peak value of any maximum peak or minimum peak included in the damped oscillation, and sets the maximum peak or minimum peak whose peak value is to be acquired as the target peak. It is preferable to repeat, for a plurality of the damped oscillations, 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.

[0010] Furthermore, it is preferable that the batteries can be graded according to their state of health (SOH) and safety (SOS).

[0011] Furthermore, the impedance measuring device is preferably used to estimate the safety state (SOS) of the battery based on the amount of metal deposition in the battery from the measured decrease in impedance.

[0012] Furthermore, it is preferable that the reuse destination of the battery can be determined according to the result of the battery grading.

[0013] Another aspect of the present invention is a battery state measuring device for a power supply system that uses a group of battery modules, each containing a battery, and is capable of connecting and disconnecting the batteries in the group of battery modules in series based on a gate drive signal from a control controller, characterized in that the device measures the battery state of the battery to be measured based on the impedance measured in the battery module, and classifies the battery according to the battery state. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a power supply system that can diagnose the state of health (SOH) and safety (SOS) during operation and that enables the classification of the battery's state. [Brief explanation of the drawing]

[0015] [Figure 1] This figure shows the basic configuration of a power supply device according to an embodiment of the present invention. [Figure 2] This is a time chart illustrating the control of the battery module in an embodiment of the present invention. [Figure 3] This figure shows the operation of the battery module in an embodiment of the present invention. [Figure 4] This is a time chart illustrating the control of the power supply device in an embodiment of the present invention. [Figure 5] This figure shows the configuration of an impedance measuring device in an embodiment of the present invention. [Figure 6] This flowchart shows the peak hold process in an embodiment of the present invention. [Figure 7] This figure shows the sequence of peak hold processing in an embodiment of the present invention. [Figure 8] This figure shows an example of the time evolution of the damped oscillation waveform of the resonant voltage in an embodiment of the present invention. [Figure 9] This figure shows the relationship between the impedance of the battery and the amount of lithium deposited in an embodiment of the present invention. [Figure 10] This figure shows the configuration of a three-phase AC power supply in an embodiment of the present invention. [Figure 11] This figure shows the AC voltage output from a three-phase AC power supply in a three-phase balanced state according to an embodiment of the present invention. [Figure 12] This is a flowchart showing the battery grading process in an embodiment of the present invention. [Figure 13] This diagram illustrates the grading of batteries and the determination of their reuse destinations in an embodiment of the present invention. [Modes for carrying out the invention]

[0016] [Basic configuration of power supply circuit] The power supply system 100 (power supply module group) in this embodiment is configured to include a battery module 102 and a control controller 104, as shown in Figure 1. The power supply system 100 is configured to include 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 (motorization) to a load (not shown) connected to terminals T1 and T2, or charge power (regeneration) from a power source (not shown) connected to terminals T1 and T2.

[0017] The battery module 102 comprises 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 each battery module 102 included in each power supply system 100 can be connected in series with each other by control from the control controller 104.

[0018] The battery 10 includes at least one secondary battery. The battery 10 can be configured by connecting multiple lithium-ion batteries, nickel-metal hydride batteries, etc., in series and / or parallel. The choke coil 12 and capacitor 14 constitute a smoothing circuit (low-pass filter circuit) that smooths 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, choke coil 12 and capacitor 14 to equalize the current in order to suppress the deterioration of the battery 10 due to increased internal resistance loss. Note that the choke coil 12 and capacitor 14 are not essential components and may be omitted.

[0019] The first switching element 16 includes a switching element for short-circuiting the output terminal of the battery 10. In this embodiment, the first switching element 16 is shown as having a recirculating diode connected in parallel with a field-effect transistor, which is a switching element. The second switching element 18 is connected in series with the battery 10 between the battery 10 and the first switching element 16. In this embodiment, the second switching element 18 is shown as having a recirculating diode connected in parallel with a field-effect transistor, which is a switching element. The first switching element 16 and the second switching element 18 are switched by a gate drive signal from the control controller 104. In this embodiment, the first switching element 16 and the second switching element 18 are field-effect transistors, but are not limited to this as long as they can be switched. For example, the first switching element 16 and the second switching element 18 may be other types of switching elements such as IGBTs.

[0020] The delay circuit 20 includes a delay circuit that delays the gate drive signal by a predetermined time. In the power supply system 100, each battery module 102 (102a, 102b, ... 102n) is provided with a delay circuit 20, and these are connected in series. Therefore, the gate drive signal input from the control controller 104 is delayed by a predetermined time and input sequentially to each battery module 102 (102a, 102b, ... 102n). Control based on the gate drive signal will be described later.

[0021] The signal processing circuit 22 is a circuit that controls the battery module 102 in accordance with control signals input to the battery module 102 from the control controller 104. 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 accordance with the 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 accordance with the 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. The output signal from the signal processing circuit 22 is input to the gate terminal of the second switch element 18. The output signal from the signal processing circuit 22 is also input to the gate terminal of the first switch element 16 via a NOT element.

[0022] During normal control, the gate drive signal from the signal processing circuit 22 is directly input to the gate terminal of the second switch element 18, and the inverted 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 the off state and the second switch element 18 is in the on state, and when the gate drive signal is at a low (L) level, the first switch element 16 is in the on state and the second switch element 18 is in the off state. In other words, when the gate drive signal is at a high (H) level, the battery 10 in the battery module 102 is connected in series with the battery 10 in other battery modules 102, and when the gate drive signal is at a low (L) level, the battery 10 in the battery module 102 is disconnected from the battery 10 in other battery modules 102, resulting in a through state.

[0023] During forced disconnection, the control controller 104 outputs a forced disconnection signal to the signal processing circuit 22 connected to the battery module 102 containing the battery to be forcibly disconnected. The forced disconnection signal is sent to the signal processing circuit 22 of the battery module 102. 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 a 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 battery module 102 is forcibly disconnected from the series connection (pass-through state) regardless of the state of the gate drive signal.

[0024] Such forced disconnection control can be used to suppress an imbalance in the State of Charge (SOC) of the batteries 10 in the battery module 102 of the power supply system 100. Specifically, when the power supply system 100 is in a discharge state, the SOC of the batteries 10 in the battery module 102 that are involved in the output of the power supply system 100 decreases, but the SOC of the batteries 10 in the battery module 102 can be maintained by forcibly disconnecting them. Also, when the power supply system 100 is in a charging state, the SOC of the batteries 10 in the battery module 102 that are involved in charging the power supply system 100 increases, but the SOC of the batteries 10 in the battery module 102 can be maintained by forcibly disconnecting them.

[0025] During forced connection, the control controller 104 sends a forced connection signal to the battery module 102 containing the battery to be forcibly connected. As a result, the signal processing circuit 22 outputs a high (H) level, 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 battery 10 in the battery module 102 is forcibly connected in series regardless of the state of the gate drive signal.

[0026] Such forced connection control can be used to suppress imbalances in the State of Charge (SOC) of the batteries 10 in the battery module 102 of the power supply system 100. Specifically, when the power supply system 100 is in a discharge state, the SOC of the batteries 10 in the battery module 102 that are forcibly connected can be reduced more quickly than the SOC of the batteries 10 in the battery module 102 that are intermittently connected in series in response to the gate drive signal. Also, when the power supply system 100 is in a charging state, the SOC of the batteries 10 in the battery module 102 that are forcibly connected can be increased more quickly than the SOC of the batteries 10 in the battery module 102 that are intermittently connected in series in response to the gate drive signal.

[0027] [Normal control] The control of the power supply system 100 will be described below with reference to Figure 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. That is, it controls the output voltage of the power supply system 100 by controlling multiple battery modules 102a, 102b, ... 102n.

[0028] The gate drive signal is transmitted sequentially to the subsequent battery modules 102, starting from the delay circuit 20 in battery module 102a, then the delay circuit 20 in battery module 102b, and so on. In other words, in the power supply system 100, the gate drive signal is delayed by a predetermined delay time in order from the upstream battery module 102 connected in series, and then transmitted to the downstream side.

[0029] During normal control, the gate drive signal from the delay circuit 20 is input to the gate terminal of the first switch element 16 as an inverted signal via a NOT element, and the gate drive signal from the delay circuit 20 is input directly to the gate terminal of the second switch element 18.

[0030] Figure 2 shows a time chart relating to the operation of the battery module 102a. Figure 2 also shows the pulse waveform of the gate drive signal D1 that drives the battery module 102a, the rectangular wave D2 indicating the switching state of the first switch element 16, the rectangular wave D3 indicating the switching state of the second switch element 18, and the voltage V output by the battery module 102a. mod This shows waveform D4.

[0031] In the initial state of the battery module 102a, that is, when no gate drive signal is output, the first switch element 16 is in the ON state and the second switch element 18 is in the OFF state. When a gate drive signal is input to the battery module 102a, the battery module 102a is switched by PWM control. In this switching control, the first switch element 16 and the second switch element 18 are alternately switched between the ON state and the OFF state.

[0032] As shown in Figure 2, when the control controller 104 outputs a gate drive signal D1, the first switch element 16 and the second switch element 18 of the battery module 102a are driven in response to this gate drive signal D1. The first switch element 16 switches from the ON state to the OFF state by the falling edge of the signal from the NOT element corresponding to the rising edge of the gate drive signal D1. The first switch element 16 also switches from the OFF state to the ON state a short time delay (dead time dt) after the falling edge of the gate drive signal D1.

[0033] On the other hand, the second switch element 18 switches from the off state to the on state with a delay of a short time (dead time dt) from the rising edge of the gate drive signal D1. Also, 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 to alternately switch between the on state and the off state.

[0034] The reason why the first switch element 16 operates with a slight delay (dead time dt) when the gate drive signal D1 falls, and the second switch element 18 operates with a slight delay (dead time dt) when the gate drive signal D1 rises, is to prevent the first switch element 16 and the second switch element 18 from being turned on simultaneously. In other words, it prevents the battery 10 from being short-circuited by the first switch element 16 and the second switch element 18 being turned on simultaneously. The dead time dt that delays this operation is set to, for example, 100ns, but can be set as appropriate. During the dead time dt, current flows back through the diode, and the switch element connected in parallel with the diode that has received the current flows back through becomes in the same state as when it is turned on.

[0035] Through this 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 terminals of the battery module 102a. Therefore, no voltage is output from the battery module 102a to the output terminals. In this state, as shown in Figure 3(a), the battery 10 (capacitor 14) of the battery module 102a is bypassed and in a through state.

[0036] 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 terminals of the battery module 102a. Therefore, a voltage is output from the battery module 102a to the output terminals. In this state, as shown in Figure 3(b), the voltage V is output via the capacitor 14 in the battery module 102a. mod This is output to the output terminal.

[0037] In other words, when the gate drive signal is at a high (H) level, the capacitor 14 and battery 10 in battery module 102 are connected in series with the capacitor 14 and battery 10 in other battery modules 102 (connected state), and when the gate drive signal is at a low (L) level, the capacitor 14 and battery 10 in battery module 102 are disconnected from the capacitor 14 and battery 10 in other battery modules 102 (through state).

[0038] Figure 4 shows a control sequence in which a predetermined number of battery modules 102a, 102b, ..., 102n are sequentially operated in a connected state to output power. As shown in Figure 4, in response to the gate drive signal, 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 Figure 4, period E1 indicates a state in which the first switch element 16 of the battery modules 102a, 102b, ..., 102n is off and the second switch element 18 is on, and the battery modules 102a, 102b, ..., 102n are outputting voltage from their output terminals (connected state). Period E2 indicates a state in which the first switch element 16 of the battery modules 102a, 102b, ..., 102n is on and the second switch element 18 is off, and the battery modules 102a, 102b, ..., 102n are not outputting voltage from their output terminals (through state). In this way, the battery modules 102a, 102b, ..., 102n are driven sequentially with a certain delay time.

[0039] Referring to Figure 4, the settings for the gate drive signal and delay time will be explained. The period T of the gate drive signal is set by summing 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 this frequency (switching frequency) will be explained later.

[0040] For the sake of simplicity, the following explanation will describe the case where forced disconnection and forced connection are not performed for each battery module 102. The ON ratio D (on duty cycle) of the gate drive signal in period T is, that is, the time T in which the gate drive signal is at a high (H) level relative to period T. ON The ratio is calculated as the output voltage of the power supply system 100 / the total voltage of battery modules 102a, 102b, ..., 102n (if the battery voltage of each battery module 102 is equal, then the battery voltage of battery module 102 × the number of battery modules). That is, the ON ratio D = (Output voltage of power supply system 100) / (Battery voltage of battery module 102 × total number of battery modules 102). Strictly speaking, the ON ratio will shift by the dead time dt, so it is preferable to correct the ON ratio using feedback or feedforward, as is commonly done in chopper circuits.

[0041] As described above, the output voltage of the power supply system 100 is expressed as the value obtained by multiplying the battery voltage of each battery module 102 by the number of battery modules 102 that are connected, provided that the battery voltages of each battery module 102 are equal. If the output voltage of the power supply system 100 is divisible by the battery voltage of one battery module 102, then at the moment when one battery module 102 switches from the pass-through state to the connected state, the other battery modules 102 also switch from the connected state to the pass-through state, so there is no fluctuation in the overall output voltage of the battery modules 102.

[0042] However, if the output voltage of the power supply system 100 is not divisible by the battery voltage of each battery module 102, the output voltage of the power supply system 100 (the overall output voltage) will fluctuate. However, the amplitude of this fluctuation 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 fluctuation period can be shortened, and the parasitic inductance of the entire power supply system 100 can be made larger, so this voltage fluctuation can be filtered and the output voltage of the power supply system 100 can be stabilized.

[0043] Furthermore, when connected, current flows through the second switch element 18 of each battery module 102, and as shown in Figure 4, the current waveform J1 of the second switch element 18 becomes a square wave. Also, since the battery 10 and capacitor 14 form an RLC filter, 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 battery modules 102a, 102b, ..., 102n, and current can be output equally from all battery modules 102a, 102b, ..., 102n.

[0044] As explained above, when controlling the power supply system 100, the gate drive signal output to the upstream battery module 102a is output to the downstream battery module 102b with a certain time delay, and then this gate drive signal is sequentially transmitted to the downstream battery modules 102 with a certain time delay. As a result, battery modules 102a, 102b, ..., 102n each output voltages sequentially with a certain time delay. These voltages are then summed up to produce the voltage of the power supply system 100. In other words, by adjusting the ON ratio D (on duty cycle) of the gate drive signal, the number of battery modules 102 that are connected simultaneously can be changed, thereby allowing the power supply system 100 to output a desired voltage.

[0045] The power supply system 100 eliminates the need for a DC-DC converter, simplifying the circuit configuration. Furthermore, it eliminates the need for balance circuits and other components that cause power loss, improving the efficiency of the power supply system 100. Additionally, since the voltage is output almost equally from multiple battery modules 102a, 102b, ..., 102n, the drive is not concentrated on a specific battery module 102, reducing the internal resistance loss of the power supply system 100.

[0046] Furthermore, by adjusting the ON ratio D, it is possible to generate a desired output voltage that is less than or equal to the sum of the battery voltages, thereby improving the versatility of the power supply system 100.

[0047] [Forced Detachment Control] Next, we will describe the control for forcibly disconnecting a battery 10 in a selected battery module 102 (102a, 102b, ..., 102n) from among multiple battery modules 102. The control 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 a 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 an ON state, the second switch element 18 is always in an OFF state, and the battery 10 in the corresponding battery module 102 is forcibly disconnected (pass-through state) regardless of the state of the gate drive signal. By using this forced disconnection control, it is possible to continue operation by disconnecting the battery 10 in a specific battery module 102 in the event of a failure.

[0048] In the event of a forced disconnection, the ON ratio D is expressed as (output voltage of power system 100) / (total voltage of battery modules 102 excluding the battery module 102 in the forced disconnection state). If a battery 10 in battery modules 102a, 102b, ... 102n fails, or if measurements are taken using the impedance measuring device 30 described later, the target battery 10 can be excluded, and the desired voltage can be obtained by resetting the gate drive signal period T and ON ratio D using only the other battery modules 102. In other words, even if a battery 10 in battery modules 102a, 102b, ... 102n is forcibly disconnected, the output of the desired voltage can be maintained. Furthermore, it can be used to control the imbalance of the SOC of the batteries 10 in battery modules 102 when there is variation in the battery capacity of each battery module 102.

[0049] For example, when the power supply system 100 is in a powering state, the batteries 10 in the battery module 102 included in the power supply system 100 that have a relatively low State of Charge (SOC) are forcibly disconnected. This reduces the power consumption (integrated discharge current per unit time) of the forcibly disconnected batteries 10, thereby resolving the imbalance in the SOC of the batteries 10 in the battery module 102. As a result, the SOC of the batteries 10 in the battery module 102 can be brought closer to the SOC control target value. Furthermore, it becomes possible to efficiently utilize the charging energy of each battery 10 in the battery module 102.

[0050] Furthermore, control can be performed to resolve the imbalance in the State of Charge (SOC) of the batteries 10 in the battery module 102 when the system is not in a powered state but in a regenerative state. In this case, the system forcibly disconnects the batteries 10 in the battery module 102 with relatively high SOCs and preferentially regenerates power to the batteries 10 in the battery module 102 with relatively low SOCs, thereby resolving the imbalance in the SOCs of the batteries 10 in the battery module 102. In other words, the power supply (integrated charging current per unit time) to the batteries 10 in the battery module 102 with relatively high SOCs is reduced, thereby resolving the imbalance in the SOCs of the batteries 10 in the battery module 102. As a result, the SOC of the batteries 10 in the battery module 102 can be brought closer to the SOC control target value. In addition, all batteries 10 in the battery module 102 included in the power supply system 100 can be charged in a balanced manner. Furthermore, overcharging of batteries 10 in the battery module 102 with small charging capacity can be prevented.

[0051] Furthermore, forced disconnection control can be used to suppress the deterioration of the battery 10 in the battery module 102 of the power supply system 100. That is, if metal deposition becomes significant inside the battery 10, or if damage or other abnormalities occur in the battery 10, the battery 10 can be forcibly disconnected to suppress metal deposition or delay the progression of the abnormality.

[0052] [Forced connection control] Next, we will describe the control for forcibly connecting a selected battery 10 from among the multiple battery modules 102 (102a, 102b, ... 102n). The control controller 104 outputs a forced connection signal to the signal processing circuit 22 of the battery module 102 that is to be forcibly connected.

[0053] 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 to suppress the state of charge (SOC) imbalance of the batteries 10 in the battery module 102 of the power supply system 100.

[0054] For example, when the power supply system 100 is in a regenerative state, by forcibly connecting a battery 10 in a battery module 102 that has a relatively low State of Charge (SOC), charging of the forcibly connected battery 10 is prioritized using regenerative power, increasing the cumulative charge current per unit time and resolving the imbalance in the SOC of the batteries 10 in the battery module 102. As a result, the SOC of the batteries 10 in the battery module 102 can be brought closer to the SOC control target value. Furthermore, all batteries 10 in the battery modules 102 included in the power supply system 100 can be charged in a balanced manner.

[0055] Furthermore, control can be performed to resolve the imbalance in the State of Charge (SOC) of the batteries 10 in the battery module 102 included in the power supply system 100, not in a regenerative state, but in a powered state. In this case, control is performed to forcibly connect the batteries 10 in the battery module 102 with a relatively high SOC, thereby increasing the power consumption of the batteries 10 in the battery module 102 with a relatively high SOC and resolving the SOC imbalance. In other words, the power supply (integrated discharge current per unit time) from the batteries 10 in the battery module 102 with a relatively high SOC becomes larger, and the imbalance in the SOC of the batteries 10 in the battery module 102 can be resolved. As a result, the SOC of the batteries 10 in the battery module 102 can be brought closer to the SOC control target value. In addition, it becomes possible to efficiently use up the charging energy of all the batteries 10 in the battery module 102 included in the power supply system 100.

[0056] Furthermore, the battery module 102 containing the malfunctioning battery 10 can be forcibly discharged by forcibly connecting the module. After that, the battery module 102 can be forcibly disconnected to safely remove the battery 10 from the power system 100 and replace it with another battery 10.

[0057] [Impedance measurement] In the power supply system 100, an impedance measuring device 30 is provided for each of the battery modules 102. The impedance measuring device 30 is used to measure the characteristics of the batteries 10 contained in each of the battery modules 102.

[0058] As shown in Figure 5, the impedance measuring device 30 in the embodiment of the present invention is configured to include a resonant circuit 32, a differential single-ended converter circuit 34, and a peak hold circuit 36. The impedance measuring device 30 is connected to a battery 10 (battery BAT) and acquires, holds, and outputs the peak voltage value of any maximum or minimum peak included in a signal having a damped oscillation waveform generated by the resonant circuit 32.

[0059] 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 by controlling the timing of opening and closing the switch SWres, and outputs it. The resonant circuit 32 consists of a resonant inductor Lres, Lsec, a resonant capacitance Cres, and a resonant resistor Rres. The resonant inductors Lres and Lsec have a transformer structure with mutual inductors M.

[0060] The differential single-ended converter circuit 34 differentially amplifies the resonant voltage Vres generated in the resonant inductor Lsec and outputs it to the peak-hold circuit 36.

[0061] The peak hold circuit 36 ​​is a non-inverting peak hold circuit that includes 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-ended converter 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 ON. On the other hand, when the resonant voltage Vres is lower than the output voltage value Vpho, it does not generate a pulse signal and turns off the switch SWch even if the switch SWsp is ON. When the switch SWsp is OFF, the switch SWch is OFF regardless of whether or not the pulse signal Vco is output from the comparator CP. When the switch SWch is ON, current flows from the charging section (voltage source) that supplies power to the charge capacitance Cc through the resistor Rc to the charge capacitance Cc, charge accumulates in the charge capacitance Cc, and the terminal voltage of the charge capacitance Cc rises. The terminal voltage of the charge capacitance Cc is then output as the output voltage value Vpho of the peak hold circuit 36. To discharge the charge stored in the charge capacitance Cc and reset it, switch SWdch is turned ON.

[0062] Here, the time constants of the resistor Rc and the charge capacitance Cc allow the terminal voltage of the charge capacitance Cc to reach the peak voltage value of the input resonant voltage Vres in a single 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 ​​becomes large due to the effects of switching delay and feedback delay. Therefore, it is preferable to set the time constants of the resistor Rc and the charge capacitance Cc to a value such that the terminal voltage of the charge capacitance Cc does not reach the peak voltage value of the resonant voltage Vres in a single operation. By providing the resistor Rc, the lower the terminal voltage of the charge capacitance Cc, the faster the charge is charged, and as the terminal voltage increases, the charge is charged more slowly, making it possible to acquire and hold the peak voltage values ​​of each peak of the resonant voltage Vres with high accuracy.

[0063] Figure 6 is a flowchart showing the peak hold process for acquiring and holding the peak voltage value of a resonant voltage Vres having a damped oscillation waveform. Figure 7 shows the sequence of the peak hold process by the impedance measuring device 30. Figure 7 shows the sequence when the second peak of the resonant voltage Vres having a damped oscillation waveform is selected as the target peak and its peak voltage value is peak-held.

[0064] In step S10, the switch SWdch is turned off, returning the charge capacity Cc from a discharged state to a state where it can accumulate charge. At this time, the count value of the number of times the process has been repeated is also reset to 0.

[0065] In step S12, the switch SWres of the resonant circuit 32 is turned from off to on. This causes the resonant voltage Vres, which has a damped oscillation waveform, to be output from the resonant circuit 32. At this time, the count value count, which is the number of iterations of the process, is increased by 1. Figure 8 shows an example of the time change of the damped oscillation waveform of the resonant voltage Vres. The resonant voltage Vres shows a peak value Vres(t1) at time t1, a peak value Vres(t2) at time t2, ... and a peak value Vres(tn) at elapsed time tn as time progresses on the horizontal axis.

[0066] In step S14, a delay process is performed for a predetermined delay time. The delay time here is set to be set from the time when switch SWres is turned on to a time after the peak immediately preceding the target peak to be peak-held in the resonant voltage Vres which has a damped oscillation waveform, and before the target peak. In particular, it is preferable to set the delay time so that switch SWsp is turned on from off at a position between 1 / 4 wavelength and 3 / 4 wavelength of the target peak. For example, in Figure 8, if the second peak of the resonant voltage Vres which has a damped oscillation waveform is the target peak to be peak-held, the delay time is set from the time when switch SWres is turned on and the resonant voltage Vres which has a damped oscillation waveform starts to be generated, to a time after the time t1 of the first peak immediately preceding the target peak, and before the time t2 of the second peak which is the target peak.

[0067] In step S16, switch SWsp is turned from off to on. This causes switch SWch to be turned on by the pulse signal Vco generated when the output voltage value Vpho in comparator CP is greater than the resonant voltage Vres.

[0068] 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. When the resonant voltage Vres is higher than the output voltage Vpho, it generates a pulse signal Vco to turn on the switch SWch. In this state, current flows through the resistor Rc to the charge capacitance Cc, charge accumulates in the charge capacitance Cc, and the terminal voltage of the charge capacitance Cc, and consequently the output voltage Vpho, rises.

[0069] As shown in the enlarged view of Figure 7, the comparator CP outputs a pulse signal Vco when the output voltage Vpho exceeds the resonant voltage Vres. Therefore, if the switch SWsp is ON, the charging of charge to 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 Vpho exceeds the resonant voltage Vres. On the other hand, when the resonant voltage Vres becomes higher than the output voltage Vpho, the comparator CP stops generating a pulse signal, and the charging of charge to the charge capacitance Cc ends.

[0070] In step S18, a delay process is performed for a predetermined delay time. The delay time here is set to be a delay from the time when the switch SWres is turned on until after the target peak to be peak-held in the resonant voltage Vres having a damped oscillation waveform, and before the time when the next resonant voltage Vres occurs. For example, in Figure 8, if the second peak of the resonant voltage Vres having a damped oscillation waveform is the target peak to be peak-held, the delay time is set to be after the time t2 of the target peak (the second peak) and before the time when the next resonant voltage Vres occurs, 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.

[0071] In step S20, switch SWsp is turned from on to off. This prevents the pulse signal Vco from the output of comparator CP from being transmitted to switch SWch, resulting in switch SWch being turned off regardless of the high / low relationship between the output voltage value Vpho and the resonant voltage Vres.

[0072] In step S22, the switch SWres of the resonant circuit 32 is turned from on to off. This stops the output of the resonant voltage Vres, which has a damped oscillation waveform, from the resonant circuit 32.

[0073] In step S24, a delay process is performed for a predetermined delay time. The delay time here is the 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 allow the previous resonant voltage Vres to decay to an extent that does not affect the next resonant voltage Vres having a damped oscillation waveform.

[0074] 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; otherwise, it returns to step S12 and the peak hold process for the same peak is repeated. The maximum count `Cntmax` should be set in advance so that the process is repeated enough to ensure that the peak hold process is performed correctly.

[0075] By repeating the process from step S12 to step S26, peak hold processing is performed as shown in the change of the output voltage value Vpho at the bottom of Figure 7. At the first resonant voltage Vres, the second, third, and fourth peaks, which undergo damped oscillations, charge is added to the charge capacitance Cc, and consequently, the output voltage value Vpho gradually increases until it reaches a voltage value higher than the fifth peak. At the second resonant voltage Vres, the second and third peaks, which undergo damped oscillations, further charge is added to the charge capacitance Cc, and consequently, the output voltage value Vpho increases further until it reaches a voltage value higher than the fourth peak. At the third resonant voltage Vres, the second and third peaks, which undergo damped oscillations, further charge is added to the charge capacitance Cc, and consequently, the output voltage value Vpho increases further until it reaches a voltage value higher than the third peak. During the 4th to 6th resonant voltage Vres, the damped oscillation of the second peak further charges the charge capacitance Cc. Consequently, the output voltage Vpho rises until it finally matches the peak voltage of the second peak, and the peak voltage value of the target peak, the second peak, is acquired and retained as the output voltage Vpho.

[0076] Thus, in the impedance measuring device 30 of this embodiment, charge is charged to the charge capacitance Cc not only by the target peak that is subject to peak hold processing, but also by other peaks included in the resonant voltage Vres which has an vibration damping waveform. Therefore, the output voltage value Vpho can be raised more quickly to the peak voltage value of the target peak by utilizing these other peaks as well.

[0077] In step S28, the output voltage value Vpho is read out. The control controller 104 reads out the output voltage value Vpho that was acquired and held in steps S10 to S26.

[0078] In step S30, it is determined whether or not to perform a peak hold on the next peak. If a peak hold is to be performed on the next peak, the process moves to step S34; if the peak hold is to be terminated, the process moves to step S32.

[0079] In step S32, the switch SWdch is turned on to discharge the charge capacity Cc and reset it, and then the peak hold process is terminated. In step S34, the next peak is set as the target peak, and the peak hold process for that target peak is started. Here, it is preferable to turn the switch SWdch on to discharge the charge capacity Cc and reset it, and then turn the switch SWdch back off. In step S36, the count value count is reset to 0, and the process is repeated from step S12.

[0080] Furthermore, by changing the target peak from a later peak with a lower peak voltage value to an earlier peak with a higher peak voltage value in the resonant voltage Vres which has a damped oscillation waveform, it becomes unnecessary to turn on the switch SWdch and discharge the charge capacity Cc after acquiring and holding the peak voltage value of each peak as the output voltage value Vpho. In other words, by acquiring, holding, and reading out the later peak with a lower peak voltage value as the output voltage value Vpho, and setting the earlier peak with a higher peak voltage value as the next target peak, it is possible to further charge the charge capacity Cc to match the peak voltage value of the next target peak without discharging the charge that had been accumulated up to that point, and then acquire and hold it as the output voltage value Vpho.

[0081] In the impedance measuring device 30, by using an integral type that charges the charge capacitance Cc multiple times, the tracking amount per cycle becomes smaller, but the accuracy of tracking the peak voltage value is increased. Therefore, even for resonant voltage Vres with a damped oscillation waveform of a high frequency exceeding 10 kHz, which is difficult to track with a single peak hold process, the peak voltage value can be acquired and held as the output voltage value Vpho with higher accuracy.

[0082] [How to calculate battery impedance] The following explains how to calculate the internal impedance of a battery (BAT).

[0083] The resonant voltage Vres(t) is expressed by equations (1) to (6). Here, Vbat is the voltage of the battery BAT, Cbat is the internal capacitance, Lbat is the internal inductance, and Rbat is the internal resistance, Cres is the resonant capacitance of the resonant circuit 32, Lres is the resonant inductance of the resonant circuit 32 (primary side) and Lsec is the resonant inductance (secondary side), M is the mutual inductance between Lres (primary side) and Lsec (secondary side), Rres is the resonant resistance, ω0 is the resonant angular frequency, Ls is the series equivalent inductance of Lres (primary side) and Lbat, Cs is the series equivalent capacitance of Cres and Cbat, tn is the elapsed time from the start of resonance, α is the attenuation rate of the decayed resonant voltage, and β is the phase difference of the decayed resonant voltage.

number

number

number

number

number

number

[0084] The resonant voltage V is the Nth resonance point. res (t n ) is expressed by formula (7).

number

[0085] For any n=n1, n2 (n1>n2), the damping rate α can be expressed by equation (8).

number

[0086] The resonance resistance R of the resonance circuit 32 res is larger than the internal resistance R of the battery BAT bat by a sufficient margin (R res >>R bat ), and the resonance angular frequency ω0 is expressed by Equation (9).

Equation

[0087] The real part impedance R of the battery BAT bat and the imaginary part impedance L bat can be obtained from Equations (10) and (11). However, it is assumed that the internal capacitance C of the battery BAT bat is very large and can be ignored.

Equation

Equation

[0088] As described above, the real part impedance Rbat and the imaginary part 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 measurement device 30.

[0089] [Method for Detecting Lithium Deposition Amount Inside Battery] FIG. 9 shows the change amount of the real part impedance (1 MHz) of the battery BAT with respect to the deposition amount of lithium (Li) when the battery BAT is a lithium ion battery. The figure shows the results of a degradation test in which commercially available cylindrical lithium ion batteries are repeatedly charged at a high rate at low temperature to deposit lithium (Li).

[0090] As shown in Figure 9, the amount of lithium (Li) deposited changes linearly with respect to the change in the real impedance of the battery (BAT). Therefore, the amount of lithium (Li) deposited in the battery (BAT) can be estimated using the formula: Lithium Deposit Amount = Change in Real Impedance of Battery (BAT) × Coefficient.

[0091] [Three-phase AC power supply system] Figure 10 shows the configuration of a three-phase AC power supply system 200 using power supply system 100. The three-phase AC power supply system 200 is composed of three sets of power supply systems 100 combined together.

[0092] The three power supply systems 100 (string a, string b, string c) are Y-connected so that the output voltage polarity of each string is the same at the neutral point. In Figure 10, the negative terminals of the three power supply systems 100 (string a, string b, string c) are connected to the neutral point, but the positive terminals of all strings may also be connected to the neutral point.

[0093] In the three-phase AC power supply system 200, the number of connected batteries 10 in the battery module 102 is controlled to change over time in each of the three sets of power supply systems 100, strings a to c, thereby controlling the AC voltage E a ,E b ,E c This generates AC power. Specifically, in each of the power supply systems 100, the number of battery modules 102 that are connected simultaneously is changed by independently adjusting the ON ratio D (on duty cycle) of the gate drive signal, thereby changing the output voltage over time.

[0094] However, since each of the power supply systems 100 can only generate a voltage of 0V or higher, as shown in Figure 11, the AC voltage E a ,E b ,E c It generates voltages with an offset, each having a phase difference of 120°.

[0095] Furthermore, by generating an AC voltage with the same offset voltage in each of strings a to c, the line voltage V uv ,V vw ,V wu This allows for the generation of positive and negative AC voltages with an average voltage of 0V. As a result, manufacturing costs can be reduced by using a half-bridge circuit in the battery module 102 included in the power supply system 100, instead of using a full-bridge circuit with four switches.

[0096] The output terminals of strings a to c are connected to filter 202. Filter 202 is connected to the 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 The system can be configured to include the following: Filter 202 is provided for each phase of string a to c. The filter capacitors are connected at the neutral point. The output of filter 202 is connected to the secondary side of transformer 204. A relay may be provided between filter 202 and transformer 204.

[0097] Additionally, a current sensor (I) is used to measure the output current of strings a to c. a , I b , I c ) may be provided. Current sensors may be installed for only two phases, and the remaining phase may be calculated from the measured phase currents of the two phases. For example, the current of phase a I a and the current I of phase b b When measuring, the current I of the c-phase c is I c =-I a -I b It can be calculated using this method.

[0098] Additionally, a voltage sensor (V) measures the voltage of the three filter capacitors of filter 202. u, V v , V w A filter capacitor may be provided. By measuring the filter capacitor voltage, the phase voltages of the system can be measured.

[0099] [Battery grading process] In this embodiment, the power supply system 100 performs a process to classify the batteries according to the battery state of each battery module 102's battery 10 as measured by the impedance measuring device 30.

[0100] The grading process for the battery 10 in the power supply system 100 will be explained below with reference to the flowchart in Figure 12. The grading process for the battery 10 is performed in the control controller 104.

[0101] In step S40, the batteries 10 are inserted into each battery module 102 of the power supply system 100. That is, the batteries 10 are connected to the battery modules 102.

[0102] In step S42, the operation of the power supply system 100 is started. For control of the power supply system 100, one of the following can be applied: constant current charge / discharge control (CC charge / discharge control), constant voltage charge / discharge control (CV charge / discharge control), or forced disconnection control. Constant current charge / discharge control (CC charge / discharge control) controls the current output from each battery module 102 to a constant value by adjusting the ON ratio D in the normal control described above. In addition, constant voltage charge / discharge control (CV charge / discharge control) controls the voltage output from each battery module 102 to a constant value by adjusting the ON ratio D in the normal control described above.

[0103] When controlling the battery module 102 according to the voltage of the battery 10, it is preferable to apply the above-mentioned normal control, forced disconnection control, and forced connection control to perform constant current charge / discharge control (CC charge / discharge control) or constant voltage charge / discharge control (CV charge / discharge control) so that the output voltage of each battery module 102 becomes a desired value.

[0104] In step S44, control is performed to put the battery module 102 containing the battery 10 to be diagnosed into a pass-through state. For example, by sequentially delaying the gate drive signal and transmitting it to each battery module 102, the battery module 102 containing the battery 10 to be diagnosed can be put into a pass-through state. Alternatively, for example, the battery module 102 containing the battery 10 to be diagnosed can be put into a pass-through state by sending a forced disconnection signal from the control controller 104 to the battery module 102 containing the battery 10 to be diagnosed. Note that there may be multiple battery modules 102 to be diagnosed.

[0105] In step S46, the battery state of the battery 10 to be diagnosed, contained in the battery module 102 which is in a pass-through state, is measured. Specifically, the state of health (SOH) of the battery 10 to be diagnosed can be determined based on the impedance measurement by the impedance measuring device 30. That is, the higher the impedance, the lower the state of health (SOH) of the battery 10 to be diagnosed. Furthermore, specifically, the safety state (SOS) of the battery 10 to be diagnosed can be determined according to the deposition state of metals such as lithium based on the impedance measurement. That is, the greater the deposition of metals such as lithium, the lower the safety state (SOS) of the battery 10 to be diagnosed.

[0106] In step S48, the battery 10 to be diagnosed is graded. In this embodiment, the battery 10 is graded according to the battery state measured in step S46. Specifically, the battery 10 is assigned to one of several grades according to the combination of its health state (SOH) and safety state (SOS).

[0107] Figure 13 shows a diagram illustrating the classification of batteries and the determination of their reuse destinations. The state of health (SOH) of battery 10 is a predetermined first health condition standard value T. SOH1 The above conditions are met and the safety status (SOS) of the battery 10 is at its highest value, and the safety status (SOS) of the battery 10 is at a predetermined first safety status standard value T SOS1If the above conditions are met and the state of health (SOH) of the battery 10 is at its highest value, and the result is a straight line connecting these conditions, then the battery 10 is assigned the grade G1. Furthermore, if the state of health (SOH) of the battery 10 is at a predetermined second health condition standard value T SOH2 The above conditions are met and the safety status (SOS) of battery 10 is equal to the predetermined second safety status criterion value T. SOS2 In addition, if the battery 10 does not meet the criteria for Grade G1, it will be assigned to Grade G2. Here, the first health condition criterion value T SOH1 This is the second safety condition criterion value T. SOS2 Set it to a larger value. Also, the first safety condition criterion value T SOS1 This is the second safety condition criterion value T. SOS2 Set to a larger value. Also, the state of health (SOH) of battery 10 is set to the predetermined second health condition standard value T. SOH2 If less than or if the battery 10's safety state (SOS) is below the specified second safety state criterion value T SOS2 If the value is less than the specified value, the battery 10 shall be assigned to grade G3.

[0108] Furthermore, the reuse destination may be determined according to the grade of the battery 10. For example, a Grade G1 battery 10 may be determined to be usable for use in mobile vehicles such as electric vehicles and hybrid vehicles. Also, for example, a Grade G2 battery 10 may be determined to be usable as a battery for stationary power generation. Also, for example, a Grade G3 battery 10 may be determined to be eligible for recycling.

[0109] Preferably, the results of the battery 10 classification and the determination of its reuse destination are presented as information that can be accessed by administrators, etc., from the control controller 104.

[0110] According to this embodiment, by utilizing the pass-through state of the power supply system 100, the AC impedance of the batteries 10 in each battery module 102 can be measured without stopping the overall operation of the power supply system 100. From the AC impedance measurement results, the battery status, such as the state of health (SOH) and safety status (SOS), can be determined, and a diagnosis regarding the batteries 10 can be made based on the battery status.

[0111] [Structure of the invention] [Configuration 1] A power supply system that uses a group of battery modules, each containing a battery, and is capable of connecting and disconnecting the batteries in the group of battery modules in series based on a gate drive signal from a control controller, The battery module is equipped with an impedance measuring device for measuring its impedance, A power supply system characterized in that, during system operation, the impedance measuring device measures the battery state of the battery to be measured, and the battery can be classified according to the battery state. [Configuration 2] The power supply system described in Configuration 1, The impedance measuring device is a power supply system characterized by using a resonant circuit to cause an alternating current to undergo damping oscillations and measuring the impedance according to the damping rate of the damping oscillations. [Configuration 3] The power supply system described in Configuration 2, The impedance measuring device includes a peak hold circuit that acquires the peak value of any maximum or minimum peak included in the damped oscillation. A power supply system characterized in that the maximum or minimum peak of the target for which the peak value is to be acquired is designated as the target peak, and the process of starting to hold the value of the damped oscillation at a time before the target peak and stopping the holding of the value of the damped oscillation at a time after the target peak is repeated for a plurality of damped oscillations. [Structure 4] A power supply system with configuration 1 or 2, A power supply system characterized in that it is possible to classify the batteries according to their state of health (SOH) and safety (SOS) as the battery state. [Composition 5] The power supply system described in Configuration 4, The power supply system is characterized in that the impedance measuring device estimates the safety state (SOS) of the battery based on the amount of metal deposition in the battery from the measured decrease in impedance. [Composition 6] A power supply system as described in any one of items 1 to 5, A power supply system characterized by being able to determine the reuse destination of the batteries according to the results of the battery grading. [Composition 7] A battery state measuring device in a power supply system that uses a group of battery modules, each containing a battery, and is capable of connecting and disconnecting the batteries in the group of battery modules in series based on a gate drive signal from a control controller, A battery state measuring device characterized by measuring the battery state of a battery to be measured based on the impedance measured in the battery module, and classifying the battery according to the battery state. [Explanation of Symbols]

[0112] 10 Batteries, 12 Choke coils, 14 Capacitors, 20 Delay circuits, 22 Signal processing circuits, 24 OR elements, 30 Impedance measuring devices, 32 Resonant circuits, 34 Differential single-ended converter circuits, 36 Peak hold circuits, 100 Power supply systems, 102 Battery modules, 104 Control controllers, 200 Three-phase AC power supply systems, 202 Filters, 204 Transformers.

Claims

1. A power supply system that uses a group of battery modules, each containing a battery, and is capable of connecting and disconnecting the batteries in the group of battery modules in series based on a gate drive signal from a control controller, The battery module is equipped with an impedance measuring device for measuring its impedance, A power supply system characterized in that, during system operation, the impedance measuring device measures the battery state of the battery to be measured, and the battery can be classified according to the battery state.

2. A power supply system according to claim 1, The impedance measuring device is a power supply system characterized by using a resonant circuit to cause an alternating current to undergo damping oscillations and measuring the impedance according to the damping rate of the damping oscillations.

3. A power supply system according to claim 2, The impedance measuring device includes a peak hold circuit that acquires the peak value of any maximum or minimum peak included in the damped oscillation. A power supply system characterized in that the maximum or minimum peak of the target for which the peak value is to be acquired is designated as the target peak, and the process of starting to hold the value of the damped oscillation at a time before the target peak and stopping the holding of the value of the damped oscillation at a time after the target peak is repeated for a plurality of damped oscillations.

4. A power supply system according to claim 1 or 2, A power supply system characterized in that the batteries can be graded according to their state of health (SOH) and safety status (SOS).

5. A power supply system according to claim 4, The power supply system is characterized in that the impedance measuring device estimates the safety state (SOS) of the battery based on the amount of metal deposition in the battery from the measured decrease in impedance.

6. A power supply system according to claim 1, A power supply system characterized by being able to determine the reuse destination of the batteries according to the results of the battery grading.

7. A battery state measuring device in a power supply system that uses a group of battery modules, each containing a battery, and is capable of connecting and disconnecting the batteries in the group of battery modules in series based on a gate drive signal from a control controller, A battery state measuring device characterized by measuring the battery state of a battery to be measured based on the impedance measured in the battery module, and classifying the battery according to the battery state.

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