Power supply system

Abstract

To provide a power supply system capable of improving inter-phase unbalance in residual capacity, that efficiently improves intra-phase variation in residual battery capacity.SOLUTION: According to a power supply system 100 capable of mutually connecting in series or separating batteries 10 inside a plurality of battery modules 102 based on a gate drive signal from a controller 104 by using a plurality of sets of battery module groups (strings) comprising the plurality of battery modules 102 provided with the batteries 10, respectively; pass-through control for resolving variation in residual capacity between the batteries 10 inside the battery module groups, and balancing control for resolving variation in residual capacity of the batteries 10 each between the battery module groups are performed in combination to search the number of paths of the batteries 10 separated inside the battery module groups according to the pass-through control so as to maximize a charge / discharge power amount in the battery module groups.SELECTED DRAWING: Figure 12

Description

[Technical Field]

[0001] The present invention relates to a power supply system. [Background technology]

[0002] Power supply devices are currently in use that connect multiple battery modules in series to supply power to a load (powering). If the batteries included in the battery modules are secondary batteries, the batteries can be charged (regenerated) from the load side. One such power supply device has been proposed that includes a switching circuit that connects or disconnects each battery module to or from the load based on a gate drive signal (Patent Document 1).

[0003] In a power supply system in which multiple battery modules are connected in series, a power supply system has been disclosed that can forcibly pass through specific battery modules to eliminate variations in remaining capacity among the battery modules, thereby equalizing the remaining capacity (Patent Document 2).

[0004] Also disclosed is a power supply system that uses multiple battery module groups, each of which has multiple battery modules connected in series, to generate a three-phase AC voltage by generating an AC voltage with a different phase for each battery module (Patent Document 3). By making the offset voltage of the AC voltage variable, the output power for each phase can be unbalanced, and control that eliminates variations in the remaining battery capacity for each phase is shown. A control method that makes the offset voltage variable is said to enable unbalance control without reducing the power factor. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2018-074709 [Patent Document 2] Japanese Patent Application Publication No. 2018-174607 [Patent Document 3] Japanese Patent Application Publication No. 2023-132711 Summary of the Invention [Problem to be solved by the invention]

[0006] In pass-through control, in order to correct imbalances in the remaining capacity of batteries in a battery module group consisting of multiple battery modules connected in series, the batteries are forcibly put into a disconnected state (pass-through state) so that they are not involved in input / output in the battery module group. Therefore, the voltage that can be output from the battery module group decreases depending on the number of batteries that are put into the disconnected state (pass-through state).

[0007] In imbalance control, offset voltages are set between multiple battery module groups to correct imbalances in the remaining capacity of each battery module group. At this time, the load sharing rate for each battery module group is determined according to the remaining capacity ratio of each battery module group. That is, the maximum output voltage when the offset voltage is varied is calculated, and if the maximum output voltage is equal to or less than the voltage that each battery module group can output, the calculated sharing rate is adopted. If it exceeds the maximum output voltage, the sharing rate for each battery module group is reduced and recalculated.

[0008] If the number of batteries in the disconnected state (pass-through state) is fixed, the sharing rate of each battery module group is limited according to the voltage it can output, which may prevent the imbalance in remaining capacity among multiple battery module groups from being properly corrected through imbalance control. Furthermore, if the number of batteries in the disconnected state (pass-through state) is set to a small number, the voltage it can output from each battery module group increases, easing the sharing rate restriction for imbalance control. On the other hand, the pass-through control's ability to equalize remaining capacity among each battery module group may be reduced, which may prevent the variance in battery capacity among each battery module group from being properly corrected. [Means for solving the problem]

[0009] One aspect of the present invention is a power supply system that uses multiple battery module groups, each including a plurality of battery modules having batteries, and is capable of serially connecting or disconnecting the batteries in the multiple battery modules based on a gate drive signal from a control controller.The power supply system combines pass-through control to eliminate variations in remaining capacity among the batteries in the battery module groups, and imbalance control to eliminate variations in remaining capacity among the batteries in the battery module groups, and searches for the number of paths for the batteries to be disconnected within the battery module groups in the pass-through control so as to maximize the amount of charging and discharging power in the battery module groups.

[0010] Here, it is preferable to determine the change in the amount of charge / discharge power in the battery module group when the number of paths is changed while charging / discharging in the battery module group, and to search for the number of paths that maximizes the amount of charge / discharge power in the battery module group based on the change in the amount of charge / discharge power.

[0011] It is also preferable to change the number of paths at the timing when charging and discharging of the battery module group is completed.

[0012] It is also preferable that the process of searching for the number of paths is executed at least one of when the system starts operating, when the battery is replaced, and when a certain period of time has elapsed during system operation. [Effects of the Invention]

[0013] According to at least one aspect of the present invention, it is possible to provide a power supply system that can efficiently improve the variation in remaining capacity of batteries within a phase and improve the imbalance in remaining capacity between phases. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a diagram showing a basic configuration of a power supply device according to an embodiment of the present invention; [Figure 2]4 is a time chart illustrating control of a battery module according to an embodiment of the present invention. [Figure 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. [Figure 5] 1 is a diagram showing a configuration of a three-phase AC power supply according to an embodiment of the present invention. [Figure 6] 3 is a diagram showing AC voltages in a three-phase balanced state output from a three-phase AC power supply in the embodiment of the present invention. FIG. [Figure 7] 3 is a diagram showing an AC voltage output from a three-phase AC power supply in an embodiment of the present invention when the three phases are unbalanced. FIG. [Figure 8] 1 is a diagram showing a specific example of the configuration of a three-phase AC power supply according to an embodiment of the present invention. [Figure 9] 1 is a diagram showing a control block of a system interconnection control of a three-phase AC power supply in an embodiment of the present invention. [Figure 10] FIG. 10 is a diagram illustrating a state in which unbalance control should be prioritized. [Figure 11] FIG. 10 is a diagram illustrating a state in which pass-through control should be prioritized. [Figure 12] 10 is a flowchart showing a process for setting the number of paths and the amount of charge / discharge power in the embodiment of the present invention. [Figure 13] 10 is a flowchart showing a process for setting the number of paths and the amount of charge / discharge power in the embodiment of the present invention. [Figure 14] FIG. 10 is a diagram illustrating a path number search process according to an embodiment of the present invention. [Figure 15] FIG. 10 is a diagram illustrating a path number search process according to an embodiment of the present invention. [Figure 16] FIG. 10 is a diagram illustrating a path number search process according to an embodiment of the present invention. [Figure 17] 10A and 10B are diagrams illustrating an example of execution timing of a path number search process according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] [Basic configuration of power supply circuit] 1, the power supply circuit 100 (power supply module group) in this embodiment is configured to include a battery module 102 and a controller 104. The power supply circuit 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 circuit 100 can supply power (power running) to a load (not shown) connected to terminals T1 and T2, or can charge (regenerate) power from a power source (not shown) connected to terminals T1 and T2.

[0016] 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 circuit 100 can be connected in series with each other under the control of a controller 104.

[0017] Battery 10 includes at least one secondary battery. Battery 10 can be configured, for example, by connecting multiple lithium-ion batteries, nickel-metal hydride batteries, etc. in series and / or parallel. Choke coil 12 and capacitor 14 form a smoothing circuit (low-pass filter circuit) that smooths and outputs the output from battery 10. That is, because a secondary battery is used as battery 10, an RLC filter is formed by battery 10, choke coil L, and capacitor 14 to level the current in order to suppress deterioration of battery 10 due to increased internal resistance loss. Note that choke coil 12 and capacitor 14 are not essential components and may be omitted.

[0018] 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, which is 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, which is 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 other types of switch elements, such as IGBTs, may also be used.

[0019] The delay circuit 20 is a circuit that delays the gate drive signal by a predetermined time. In the power supply circuit 100, a delay circuit 20 is provided for each battery module 102 (102a, 102b, ... 102n), and these battery modules 102 are connected in series. Therefore, the gate drive signal input from the 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.

[0020] The signal processing circuit 22 constitutes 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. The signal processing circuit 22 also constitutes 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. The signal processing circuit 22 is controlled by receiving control signals Ss (Ss1, Ss2, ... Ssn) from the controller 104 that include a forced disconnection signal or a forced connection signal. During normal control, the controller 104 inputs a control signal Ss to the signal processing circuit 22 that indicates that control should be performed based on a gate drive signal. Therefore, when the gate drive signal is at a high (H) level, the second switch element 18 is turned on and the first switch element 16 is turned off. On the other hand, when the gate drive signal is at a low (L) level, the first switch element 16 is turned on and the second switch element 18 is turned off. 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 disconnected from the batteries 10 in the other battery modules 102 and are in a through state.

[0021] During forced disconnection (pass-through), the controller 104 transmits a control signal Ss including a forced disconnection signal to the signal processing circuit 22 of the battery module 102 to be forcibly disconnected. As a result, a high (H) level is input to the gate terminal of the first switch element 16, 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, and the second switch element 18 is always in an off state, so that 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. Control using a forced disconnection signal in this manner is called pass-through control.

[0022] By applying pass-through control, if a battery 10 in a specific battery module 102 fails, the battery 10 is disconnected, allowing the power supply circuit 100 to continue operating. Pass-through control can also be used to correct and suppress imbalances in the state of charge (SOC) of the batteries 10 in the battery modules 102 in the power supply circuit 100. That is, when the power supply circuit 100 is in a discharging state, the SOC of the batteries 10 in the battery modules 102 involved in the output of the power supply circuit 100 decreases. However, by forcibly disconnecting the batteries 10 in the battery modules 102, the SOC of the batteries 10 in the battery modules 102 can be maintained. When the power supply circuit 100 is in a charging state, the SOC of the batteries 10 in the battery modules 102 involved in charging the power supply circuit 100 increases. However, by forcibly disconnecting the batteries 10 in the battery modules 102, the SOC of the batteries 10 in the battery modules 102 can be maintained.

[0023] During forced connection, the controller 104 transmits a control signal Ss including a forced connection signal to the signal processing circuit 22 of the battery module 102 to be forcibly connected. As a result, a low (L) level is input to the gate terminal of the first switch element 16, 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.

[0024] The forced connection control can be used to correct and suppress imbalances in the state of charge (SOC) of the batteries 10 in the battery modules 102 in the power supply circuit 100. That is, when the power supply circuit 100 is in a discharging state, the SOC of the batteries 10 in the battery modules 102 that are forced to be connected can be reduced more quickly relative to a decrease 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. Also, when the power supply circuit 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 relative 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.

[0025] [Control by gate drive signal] Normal control in the power supply circuit 100 will be described with reference to Fig. 2. During normal control, which is neither pass-through control nor forced connection control, each battery module 102 (102a, 102b, ... 102n) is controlled based on a gate drive signal.

[0026] 2 shows a time chart relating to the operation of the battery module 102a. Also, in FIG. 2, the pulse waveform of the gate drive signal D1 that drives the battery module 102a, the square wave D2 that indicates the switching state of the first switch element 16, the square wave D3 that indicates the switching state of the second switch element 18, and the voltage V that is output by the battery module 102a are shown. mod 1 shows the waveform D4.

[0027] In the initial state of the battery module 102a, i.e., in a state where no gate drive signal is 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 from the controller 104, 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.

[0028] As shown in FIG. 2, when a 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 switches from an ON state to an OFF state in response to the rising edge of the gate drive signal D1. The first switch element 16 switches from an OFF state to an ON state with a short delay (dead time dt) from the falling edge of the gate drive signal D1. Meanwhile, the second switch element 18 switches from an OFF state to an ON state with a short delay (dead time dt) from the rising edge of the gate drive signal D1. The second switch element 18 switches from an ON state to an 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 controlled to alternate between an ON state and an OFF state.

[0029] 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 simultaneously. In other words, this prevents the first switch element 16 and the second switch element 18 from being turned on simultaneously, which would short-circuit the battery 10. 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, 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.

[0030] By 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 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 state.

[0031] 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.

[0032] 1, a description will be given of the control of the power supply circuit 100 by the controller 104. The controller 104 controls the entire battery module 102. In other words, it controls the output voltage of the power supply circuit 100 by controlling the plurality of battery modules 102a, 102b, ... 102n.

[0033] The controller 104 outputs a rectangular wave gate drive signal to each battery module 102. The gate drive signal is transmitted to the delay circuit 20 included in battery module 102a, the delay circuit 20 included in 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 order from the most upstream battery module 102 connected in series in the power supply circuit 100 to the downstream battery modules 102.

[0034] During normal control, the gate drive signal output from the delay circuit 20 of each battery module 102 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. Therefore, 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.

[0035] That is, when the gate drive signal is at a high (H) level, the capacitors 14 and batteries 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 capacitors 14 and batteries 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.

[0036] 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 FIG. 4, the battery modules 102a, 102b,..., 102n are driven sequentially from upstream to downstream with a certain delay time in response to a gate drive signal. In FIG. 4, period E1 shows a state in which the first switch elements 16 of the battery modules 102a, 102b,..., 102n are turned off and the second switch elements 18 are turned on, and the battery modules 102a, 102b,..., 102n output voltage from their output terminals (connected state). Furthermore, period E2 shows a state in which the first switch elements 16 of the battery modules 102a, 102b,..., 102n are turned on and the second switch elements 18 are turned off, and the battery modules 102a, 102b,..., 102n do not output voltage from their output terminals (through state). In this way, the battery modules 102a, 102b, . . . 102n are driven sequentially with a certain delay time.

[0037] 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. When forced disconnection and forced connection are not performed, the on-time ratio D (on-duty) in the period T of the gate drive signal, that is, the time T during which the gate drive signal is at a high (H) level relative to the period T, is ON The ratio is calculated by dividing the output voltage of the power supply circuit 100 by the total voltage of the battery modules 102a, 102b, ... 102n (if the battery voltages of the battery modules 102 are equal, this is the battery voltage of the battery module 102 × the number of battery modules). In other words, the on-time ratio D = (output voltage of the power supply circuit 100) / (battery voltage of the battery module 102 × the 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 using feedback or feedforward, as is commonly done in chopper circuits.

[0038] As described above, when controlling the power supply circuit 100, the gate drive signal output to the most upstream battery module 102a is output to the downstream battery module 102b with a fixed delay, and this gate drive signal is then transmitted sequentially to the downstream battery modules 102 with a fixed delay, so that the battery modules 102a, 102b, ... 102n each output a voltage sequentially with a fixed delay. These voltages are then summed to output the voltage of the power supply circuit 100. This allows the power supply circuit 100 to output a desired voltage.

[0039] The power supply circuit 100 does not require a DC-DC converter, simplifying the circuit configuration. It also does not require a balancing circuit or the like that generates power loss, improving the efficiency of the power supply circuit 100. Furthermore, because the multiple battery modules 102a, 102b, ..., 102n output voltages approximately evenly, driving is not concentrated on a specific battery module 102, and internal resistance loss in the power supply circuit 100 can be reduced.

[0040] 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 circuit 100.

[0041] [Adjustment process for remaining battery capacity (SOC)] When pass-through control (forced disconnection control) is applied, the on-time ratio D is expressed as (output voltage of the power supply circuit 100) / (total voltage of the battery modules 102 excluding the battery module 102 in the forced disconnection state). If a failure occurs in a battery 10 in the battery modules 102a, 102b, ... 102n or if the remaining capacity (SOC) needs to be adjusted, the desired voltage can be obtained by excluding the battery 10 and using only the other battery modules 102, and resetting the period T of the gate drive signal and the on-time ratio D. In other words, even if the batteries 10 in the battery modules 102a, 102b, ... 102n are forcibly disconnected, the desired voltage can be continuously output.

[0042] Furthermore, pass-through control can be used to suppress imbalances in the SOC of the batteries 10 in the battery modules 102 when there is variation in the battery capacities of the individual battery modules 102. For example, when the power supply circuit 100 is in a powering state, by forcibly disconnecting the batteries 10 in the battery modules 102 with a relatively low remaining capacity (SOC) among the batteries 10 in the battery modules 102 included in the power supply circuit 100, the power consumption (integrated amount of discharge current per unit time) of the forcibly disconnected batteries 10 is reduced, thereby eliminating imbalances in the remaining capacity (SOC) of the batteries 10 in the battery modules 102. As a result, the remaining capacity (SOC) of the batteries 10 in the battery modules 102 can be brought closer to the control target value. Furthermore, the charging energy of the batteries 10 in each battery module 102 can be efficiently used up.

[0043] Furthermore, control can be performed to eliminate imbalances in the state of charge (SOC) of the batteries 10 in the battery modules 102 when the power supply circuit 100 is not in a powering state but in a regenerating state. In this case, control is performed to forcibly disconnect the batteries 10 in the battery modules 102 with a relatively high state of charge (SOC), and power is preferentially regenerated to the batteries 10 in the battery modules 102 with a relatively low state of charge (SOC), thereby eliminating imbalances in the state of charge (SOC) of the batteries 10 in the battery modules 102. That is, the power supply (accumulated amount of charging current per unit time) to the batteries 10 in the battery modules 102 with a relatively high state of charge (SOC) is reduced, thereby eliminating imbalances in the state of charge (SOC) of the batteries 10 in the battery modules 102. As a result, the state of charge (SOC) of the batteries 10 in the battery modules 102 can be brought closer to the control target value. Furthermore, the batteries 10 in all of the battery modules 102 included in the power supply circuit 100 can be charged in a balanced manner. Furthermore, it is possible to prevent overcharging of the batteries 10 in the battery module 102 with a small charge capacity.

[0044] Furthermore, the forced connection control can be used to suppress imbalances in the state of charge (SOC) of the batteries 10 in the battery modules 102 in the power supply circuit 100. For example, when the power supply circuit 100 is in a regenerative state, by forcibly connecting the batteries 10 in the battery modules 102 included in the power supply circuit 100 that have a relatively low state of charge (SOC), charging the forcibly connected batteries 10 with regenerative power is prioritized, increasing the integrated amount of charging current per unit time and eliminating imbalances in the state of charge (SOC) of the batteries 10 in the battery modules 102. As a result, the state of charge (SOC) of the batteries 10 in the battery modules 102 can be brought closer to a control target value. Furthermore, the batteries 10 in all of the battery modules 102 included in the power supply circuit 100 can be charged in a balanced manner.

[0045] Furthermore, control can be performed to eliminate imbalances in the state of charge (SOC) of the batteries 10 in the battery modules 102 included in the power supply circuit 100 when the power supply circuit 100 is in a powering state rather than a regeneration state. In this case, control is performed to forcibly connect the batteries 10 in the battery modules 102 with a relatively high state of charge (SOC), thereby increasing the amount of power consumed by the batteries 10 in the battery modules 102 with a relatively high state of charge (SOC), thereby eliminating the imbalances in the state of charge (SOC). In other words, the power supply (integrated amount of discharge current per unit time) from the batteries 10 in the battery modules 102 with a relatively high state of charge (SOC) increases, thereby eliminating the imbalances in the state of charge (SOC) of the batteries 10 in the battery modules 102. As a result, the state of charge (SOC) of the batteries 10 in the battery modules 102 can be brought closer to the control target value. Furthermore, it is possible to efficiently use up the charged energy of the batteries 10 in all battery modules 102 included in the power supply circuit 100.

[0046] [Application to three-phase AC power supply] 5 shows the configuration of a three-phase AC power supply 200 that uses the power supply circuit 100. The three-phase AC power supply 200 is configured by combining three sets of power supply circuits 100 (battery module groups).

[0047] The three power supply circuits 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 Fig. 5, the negative pole sides of the three power supply circuits 100 (string a, string b, string c) are connected to the neutral point, but the positive pole sides of all strings may be connected to the neutral point.

[0048] In the three-phase AC power supply 200, the number of batteries 10 connected in the battery module 102 in each of the three sets of power supply circuits 100 of strings a to c is controlled, thereby controlling the AC voltage E a ,E b ,E c That is, in each of the power supply circuits 100, the on-time ratio D (on-duty) is changed over time to generate the AC voltage Ea ,E b ,E c The on-time ratio D (on-duty) can be set according to the time change in the output voltage required for each power supply circuit 100. For example, if it is desired to change the output voltage of each power supply circuit 100 so that it exhibits a sinusoidal waveform over time, the on-time ratio D (on-duty) of the gate drive signal for each power supply circuit 100 can be changed to control the number of batteries 10 connected so that the output voltage exhibits a sinusoidal waveform.

[0049] Since each of the power supply circuits 100 can only generate a voltage of 0 V or higher, as shown in FIG. a ,E b ,E c and generate voltages with a phase difference of 120°.

[0050] 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 wu This allows the battery module 102 included in the power supply circuit 100 to generate positive and negative AC voltages with an average voltage of 0 V. This allows for a reduction in manufacturing costs by using a half-bridge circuit instead of a full-bridge circuit using four switches in the battery module 102.

[0051] When the three phases are in a balanced state, the offset voltage V ofs On the other hand, in order to suppress a drop in the power factor of the entire power supply system while unbalancing the power supply of each phase and averaging the battery capacity, the offset voltage is controlled to be constant during balanced control, and is controlled to change over time during unbalanced control.

[0052] As shown in Fig. 8, the output terminals of the strings a to c are connected to a filter 202. The filter 202 is connected to an interconnection reactor L m (L mu ,Lmv ,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. A filter 202 is provided for each phase of strings a to c. A filter capacitor is connected to the neutral point. The output of the filter 202 is connected to the secondary side of a transformer 204. A relay may be provided between the filter 202 and the transformer 204.

[0053] In addition, a current sensor (I a , I b , I c ) is provided. Current sensors may be installed 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 can be calculated using formula (1).

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[0054] Also, 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.

[0055] The following describes in detail the grid interconnection control of the three-phase AC power supply 200. Block diagrams of the grid interconnection control are shown in Figures 8 and 9.

[0056] 9, the calculation of the voltage command values ​​of the strings a to c will be described. First, the three filter capacitors C fu ,C fv ,Cfw The measured value V of the system phase voltage measured by the voltage sensor installed in u ,V v ,V w The phase θg of the system voltage is calculated by a PLL (Phase Locked Loop) using the above.

[0057] Next, the voltage phase θg and the system phase voltage V u ,V v ,V w By performing abc / dq conversion using d , v q The abc / dq0 transformation can be performed using equations (2) and (3). Here, u in equation (2) is calculated. a ,u b ,u c The system phase voltage V u ,V v ,V w Just substitute in.

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[0058] Also, u in equation (2) a ,u b ,u c The current I of strings a to c is a ,I b ,I c By substituting and performing dq transformation, the dq axis current i d , i q can be calculated.

[0059] Next, the current command value of the dq axis is calculated. If the command power for the entire three-phase AC power supply 200 is P, the d-axis command current i is calculated from the equation (4) using the d-axis voltage vd and the command power P. dcom The q-axis current command value i qcom is set to 0 to control the reactive power to zero.

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[0060] Next, the dq axis command current i dcom ,i qcom and dq axis current i d ,i q Using this, the dq axis command voltage feedback term vdfb * and vqfb * By adding these feedback terms to the vd command feedforward term and the vq command feedforward term, the dq-axis voltage command value v d * , v q * Furthermore, by converting from the dq axis to the three-phase abc axis, the voltage command value V a * , V b * , V c * The dq / abc conversion can be performed using equation (5).

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[0061] Next, the ON time command values ​​of the power supply circuit 100 for the a-phase, b-phase, and c-phase are calculated using the string voltage command value and equation (6).

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[0062] where V * abc is one of the voltage command values ​​for phase a, phase b, and phase c, V st_offset is the voltage command offset value, t delay is the delay time of the gate signal in each power supply circuit module, V b_ave_abc is the average voltage of each battery module of strings a, b, and c of the power supply circuit 100.

[0063] In this embodiment, the voltage command offset value V st_offsetBy making it variable, it becomes possible to control the power imbalance of each phase.

[0064] Voltage command offset value V that can handle unbalanced control of each phase st_offset are shown in the following formulas (7) to (11).

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[0065] where V ofs is the reference voltage offset value (e.g., 250 V constant), V d ,V q are the voltages after d-axis and q-axis conversion, respectively, φ is the phase difference between the voltage and current (used in reactive power commands, power factor commands, etc.), k pa ,k pb ,k pc is the distribution coefficient in each phase.

[0066] The deterioration state of the batteries that make up each string a to c is different, and the remaining power of the batteries (remaining capacity Q of the string) a ,Q b ,Q c When the remaining capacity of each phase is different, the distribution coefficient k pa ,k pb ,k pc By changing the distribution coefficient k pa ,k pb ,k pcis set small, and the required power for both charging and discharging is set small compared to other phases. However, when calculating the total remaining capacity of each string, it is preferable not to take into account the remaining capacity of the batteries included in the battery module 102 that has been forcibly disconnected by the forced disconnection control.

[0067] In addition, the partition coefficient k in the formulas (9) to (11) pa ,k pb ,k pc can be set based on, for example, Equation (12). Specifically, a remaining battery capacity estimation means for estimating the remaining capacities Qa, Qb, and Qc for each battery module 102 in strings a, b, and c may be provided, and control may be performed based on the remaining capacities Qa, Qb, and Qc estimated by the remaining battery capacity estimation means. Furthermore, instead of the remaining battery capacity estimation means, a remaining battery capacity measurement means for measuring the remaining capacities Qa, Qb, and Qc for each battery module 102 in strings a, b, and c may be provided.

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[0068] Gate drive signals (signal Gate_a, signal Gate_b, signal Gate_c) with an on period of only the on time command value calculated using equation (6) and an off period thereafter are provided to the first battery module 102 of each of strings a, b, and c of the power supply circuit 100.

[0069] In each of the battery modules 102, switching control is performed based on the gate drive signal. That is, while the gate drive signal is on, the first switch element 16 is in the off state and the second switch element 18 is in the on state, and while the gate drive signal is off, the first switch element 16 is in the on state and the second switch element 18 is in the off state. The gate drive signal is then delayed by a certain time (delay time tdelay) by a delay circuit included in the signal processing circuit 22 before being passed to the next battery module 102. After this is performed in the battery modules 102 included in each of the strings a, b, and c of the power supply circuit 100, the gate drive signal from the last battery module 102 is returned to the controller 104.

[0070] When the controller 104 receives the gate drive signal back, it transmits the gate drive signal of the next cycle. Specifically, it detects the rising edge of the gate drive signal (signal Gate_a_bk, signal Gate_b_bk, signal Gate_c_bk) returned from the final-stage battery module 102, and outputs the next gate drive signal to the first-stage battery module 102. In this way, it is possible to transmit the next gate drive signal to the battery module 102 at an appropriate timing.

[0071] Since the power of each phase is the product of each string voltage and each phase current, the voltage command offset value V st_offset By adjusting the phase current amplitude to vary the string voltage of each phase, it becomes possible to control the interphase power imbalance. In addition, since the amplitude of the phase current is constant for each phase, it becomes possible to control the imbalance at the rated power. In addition, in this embodiment, since the power output from the power supply circuit 100 to the grid is in a balanced state, a general method for transformer design can be used.

[0072] [Path number search process] In order to maintain a balance of remaining capacity (SOC) among the batteries in a battery module group (string) while also maintaining a balance in the power of each battery module group, it is necessary to appropriately set the sharing ratio among the battery module groups according to the number of batteries to be forcibly disconnected (passed through) for each battery module group and the voltage that can be output.

[0073] As shown in Figure 10, when the variation in remaining capacity (SOC) of the batteries within the battery module group in each phase is small but the variation in remaining capacity (SOC) between the phases is large, it is preferable to prioritize imbalance control between the battery module groups.On the other hand, as shown in Figure 11, when the variation in remaining capacity (SOC) between the phases is small but the variation in remaining capacity (SOC) of the batteries within the battery module group in each phase is large, it is preferable to prioritize pass-through control within each battery module.

[0074] 12 is a flowchart showing a process for setting the number of paths and the amount of charge / discharge power for the three-phase AC power supply 200. In the following description, N p : Number of passes, N p_ini : Initial number of passes, N p_lim : Upper limit of number of passes, ΔN p : Change in number of paths, k pu ,k pv ,k pw : Unbalance control ratio for each phase, η use : Charge / discharge energy, η use_s : previous value of charge / discharge power amount, η use_max : maximum charge / discharge power amount, m: calculation count value, and M: number of calculations.

[0075] In step S10, an initial setting process is performed. By the process in this step, the three-phase AC power supply 200 functions as an initial setting means. Here, the number of paths N p The initial number of passes is N p_ini , the previous charge / discharge energy value η use_s The initial value of is 0, and the change in the number of passes ΔN p The absolute value of the change in the number of passes |ΔN p |, and the initial value of the calculation count value m is set to 0. When the process is repeated multiple times in the three-phase AC power supply 200, the number of passes N p , the previous value of charge / discharge energy η use_s , the change in the number of passes ΔN p The final value from the previous execution may be used. p may be initialized to either a positive or negative value.

[0076] In step S12, a pass target battery module is selected. Through the processing in this step, the three-phase AC power supply 200 functions as a pass target battery module selection means. The controller 104 selects the number of passes N in accordance with the variation in the state of charge (SOC) of the batteries 10 in each phase of the battery module 102. p That is, during powering, the batteries 10 included in each battery module 102 are selected in ascending order of remaining capacity (SOC) to the current number of passes Np During regeneration, the current number of passes N is selected from the batteries 10 included in each battery module 102 in descending order of remaining capacity (SOC). p The battery 10 is selected as a target for pass-through control.

[0077] In step S14, the share rate of the unbalance control is calculated. By the processing in this step, the three-phase AC power supply 200 functions as a share rate calculation means. The controller 104 calculates the unbalance control k k for each battery module 102 based on the above formula (12) etc. in accordance with the variation in the state of charge (SOC) between the battery modules 102 of the three-phase AC power supply 200. pa , k pb , k pc The contribution rate will be calculated.

[0078] In step S16, charging and discharging are performed in the three-phase AC power supply 200. By the processing in this step, the three-phase AC power supply 200 functions as a charging and discharging means. p The battery 10 is pass-through controlled, and unbalance control k is performed between the battery modules 102. pa , k pb , k pc As a result, in the three-phase AC power supply 200, it is possible to reduce the variation in state of charge (SOC) between the battery modules 102, and also reduce the variation in state of charge (SOC) of the batteries 10 within each battery module 102.

[0079] In step S18, it is determined whether or not charging / discharging is completed. The processing in this step causes the three-phase AC power supply 200 to function as a charging / discharging completion determination means. If charging / discharging is completed, the processing proceeds to step S20; if not, the processing returns to step S12 to continue charging / discharging.

[0080] In step S20, the charge / discharge power amount is calculated. By the processing in this step, the three-phase AC power supply 200 functions as a charge / discharge power amount calculation means. In step S16, the controller 104 calculates the charge / discharge power amount η use Calculate the charge / discharge energy η use can be calculated by measuring the current and voltage with the controller 104 when charging and discharging are performed in each battery module 102. In addition, the charge / discharge power amount η use may be calculated.

[0081] In step S22, the number of passes N p and charge / discharge power η use The map update process is performed in this step. The process in this step causes the three-phase AC power supply 200 to function as a map update means. The map update process is performed according to the flowchart shown in FIG.

[0082] The map update process will be described below with reference to the flowchart in FIG. 13 and the explanatory diagrams of the map creation process in FIGS.

[0083] In step S30, the charge / discharge power amount η use and the previous discharged power amount η use_s By the process in this step, the three-phase AC power supply 200 functions as a charge / discharge power amount comparison means. The controller 104 compares the charge / discharge power amount η use and the previous discharged power η use_s Compared with the charge / discharge energy η use is the previous discharged power amount η use_s If it is greater, the process proceeds to step S34; if not, the process proceeds to step S32.

[0084] In step S32, the change amount ΔN in the number of passes pThe process in this step causes the three-phase AC power supply 200 to function as a sign inversion means. The controller 104 then inverts the current change amount ΔN p If the sign of is positive, it is inverted to negative, and the change in the current number of passes ΔN p If the sign of is negative, it is inverted to positive.

[0085] In step S34, a process of updating the number of paths is performed. By the process in this step, the three-phase AC power supply 200 functions as a path number updating means. The controller 104 updates the number of paths N p The change in the number of passes ΔN p Add the new number of passes N p Update as.

[0086] In step S36, a process of determining a lower limit of the number of paths is performed. By the process in this step, the three-phase AC power supply 200 functions as a path number lower limit determining means. The controller 104 determines the number of paths N updated in step S34. p Determine whether or not is less than or equal to 0. The updated number of paths N p If is equal to or smaller than 0, the process proceeds to step S38 and the number of passes N p Set to 0 and the number of passes N p If is greater than 0, the process proceeds to step S40.

[0087] In step S40, a process of determining an upper limit of the number of paths is performed. By the process in this step, the three-phase AC power supply 200 functions as a path number upper limit determining means. The controller 104 determines the number of paths N updated in step S34. p is the upper limit of the number of passes, N p_lim Determine whether the updated number of paths N is equal to or greater than the p is the upper limit of the number of passes, N p_lim If it is equal to or greater than this, the process proceeds to step S42. p The upper limit of the number of passes is N p_lim and the updated number of passes N p is the upper limit of the number of passes, N p_lim If it is less than the predetermined value, the process proceeds to step S44.

[0088] In step S44, the charge / discharge power amount is updated. By the process in this step, the three-phase AC power supply 200 functions as a charge / discharge power amount updating means. The controller 104 updates the charge / discharge power amount η calculated in step S20. use The previous value of charge / discharge energy η use_s Update as.

[0089] In step S46, the calculation count value is updated. By the process in this step, the three-phase AC power supply 200 functions as a calculation count value updating means. The controller 104 updates the calculation count value m by adding 1 to it.

[0090] In step S48, a calculation count value determination process is performed. Through the process in this step, the three-phase AC power supply 200 functions as a calculation count value determination means. The controller 104 determines whether the current calculation count value m is equal to or greater than the number of calculations M. If the current calculation count value m is equal to or greater than the number of calculations M, the process proceeds to step S50; if not, the process returns to step S12, and the charge / discharge process in the three-phase AC power supply 200 is repeated.

[0091] In step S50, the number of paths N for the maximum charge / discharge power amount point is calculated based on the completed map. p By the process in this step, the three-phase AC power supply 200 functions as a path number determining means. The controller 104 determines the path number N p and charge / discharge power η use Based on the map showing the relationship between use The number of paths N with the maximum point p As a result, the subsequent charge / discharge process in the three-phase AC power supply 200 is performed using the number of paths N p This is done by applying pass-through control to the battery 10.

[0092] 14 to 16 show the number of passes N pand charge / discharge power η use The process of creating a map showing the relationship between

[0093] As shown in Fig. 14, first, the initial value of the number of passes, N p_ini Charging and discharging are performed in the three-phase AC power supply 200, and the charge / discharge power amount η use Calculate (point A) and pass number N p ΔN p Then, charging and discharging are performed in the three-phase AC power supply 200, and the charging and discharging power amount η use Calculate (point B). Charging and discharging energy at point B η use is the previous charge / discharge energy at point A η use Since the number of passes has increased, p ΔN p Furthermore, charging and discharging are performed in the three-phase AC power supply 200, and the charging and discharging power amount η use Calculate (point C). Charging and discharging energy at point C η use is the previous charge / discharge energy at point B η use Since the number of passes has increased, p ΔN p Furthermore, charging and discharging are performed in the three-phase AC power supply 200, and the charging and discharging power amount η use Calculate (point D). Charging and discharging energy at point D η use is the previous charge / discharge energy at point C η use Since it has decreased by more than ΔN p Invert the sign of and set the number of passes N p ΔN p As described above, the charge / discharge process in the three-phase AC power supply 200 is repeated to update the map. The map is completed by repeating the map update process until the calculation count value m reaches the number of calculations M. When the map is completed, the number of paths N at point C where the amount of charge / discharge power becomes maximum is calculated. p The number of passes is determined as N p The three-phase AC power supply 200 is operated using the above.

[0094] Figure 15 shows the map creation process for other patterns. First, the initial value N p_iniCharging and discharging are performed in the three-phase AC power supply 200, and the charge / discharge power amount η use Calculate (point C) and pass number N p ΔN p Next, charging and discharging are performed in the three-phase AC power supply 200, and the charging and discharging power amount η use Calculate (point D). Charging and discharging energy at point D η use Since it has decreased from point C, ΔN p Invert the sign of and set the number of passes N p ΔN p Then, charging and discharging are performed in the three-phase AC power supply 200, and the charging and discharging power amount η use Calculate (point C). Charging and discharging energy at point C η use Since has increased from point D, the number of passes N p ΔN p Furthermore, charging and discharging are performed in the three-phase AC power supply 200, and the charging and discharging power amount η use Calculate (point B). Charging and discharging energy at point B η use Since has increased from point C, the number of passes N p ΔN p Furthermore, charging and discharging are performed in the three-phase AC power supply 200, and the charging and discharging power amount η use Calculate (point A). Charging and discharging energy at point A η use Since it has decreased from point B, ΔN p Invert the sign of and set the number of passes N p ΔN p ((5) in the figure). The map is updated by repeating the above steps. As described above, the charge / discharge process in the three-phase AC power supply 200 is repeated to update the map. The map is completed by repeating the map update process until the calculation count value m reaches the number of calculations M. When the map is completed, the number of paths N at point B, which is the maximum charge / discharge power amount, is calculated. p The number of passes is determined as N p The three-phase AC power supply 200 is operated using the above.

[0095] 16 shows the process of creating a map for another pattern. First, the initial value N p_iniCharging and discharging are performed in the three-phase AC power supply 200, and the charge / discharge power amount η use Calculate (point A) and pass number N p ΔN p Next, charging and discharging are performed in the three-phase AC power supply 200, and the charging and discharging power amount η use Calculate (point B). Charging and discharging energy at point B η use is the previous charge / discharge energy at point A η use Since the number of passes has increased, p ΔN p Then, charging and discharging are performed in the three-phase AC power supply 200, and the charging and discharging power amount η use Calculate (point C). Charging and discharging energy at point C η use is the previous charge / discharge energy at point B η use Since the number of passes has increased, p ΔN p Furthermore, charging and discharging are performed in the three-phase AC power supply 200, and the charging and discharging power amount η use Calculate (point D). Charging and discharging energy at point D η use Since has increased from point C, the number of passes N p ΔN p However, the upper limit of the number of passes is N p_lim Since the number of passes reaches N p The upper limit of the number of passes is N p_lim As described above, the charge / discharge process in the three-phase AC power supply 200 is repeated to update the map. The map is completed by repeating the map update process until the calculation count value m reaches the number of calculations M. When the map is completed, the number of paths N at point D, which is the maximum charge / discharge power amount, is p The number of passes is determined as N p The three-phase AC power supply 200 is operated using the above.

[0096] 17 shows an example of the timing of execution of the path number search process. p depends on the variation in the state of charge (SOC) of the battery 10 in the power supply system. Since the variation in the state of charge (SOC) of the battery 10 is unknown at the beginning of operation of the power supply system, it is difficult to determine the optimal number of paths N pFurthermore, when some or all of the batteries 10 in the power supply system are replaced, the optimum number of paths N p It is preferable to perform the path number search process because the remaining capacity (SOC) of the battery 10 may change. Even if the battery 10 is operated without being replaced, the degree of variation in the remaining capacity (SOC) of the battery 10 may change due to aging after a certain period of time has passed since the start of operation of the power supply system. Therefore, the path number search process may be performed every certain period of time. The period may be set appropriately, for example, one month, one year, etc.

[0097] [Configuration of the invention] [Configuration 1] A power supply system using a plurality of battery module groups each including a plurality of battery modules each having a battery, wherein the batteries in the plurality of battery modules can be connected or disconnected in series with each other based on a gate drive signal from a controller, a pass-through control for eliminating the variation in remaining capacity among the batteries within the battery module group and an imbalance control for eliminating the variation in remaining capacity among the batteries among the battery module groups; A power supply system comprising: a power supply unit for searching for the number of paths of the battery to be disconnected within the battery module group in the pass-through control so as to maximize the amount of charge / discharge power in the battery module group. [Configuration 2] The power supply system according to configuration 1, A power supply system characterized by: determining a change in the amount of charge / discharge power in the battery module group when the number of paths is changed while charging / discharging in the battery module group; and searching for the number of paths that maximizes the amount of charge / discharge power in the battery module group from the change in the amount of charge / discharge power. [Configuration 3] The power supply system according to configuration 2, A power supply system, characterized in that the number of paths is changed at the timing when charging and discharging of the battery module group is completed. [Configuration 4] The power supply system according to any one of configurations 1 to 3, The power supply system is characterized in that the process of searching for the number of paths is executed at least one of when the system starts operating, when the battery is replaced, and after a certain period of time has elapsed during system operation. [Explanation of symbols]

[0098] 10 battery, 12 choke coil, 14 capacitor, 16 first switch element, 18 second switch element, 20 delay circuit, 22 signal processing circuit, 100 power supply circuit, 102 battery module, 104 control controller, 200 three-phase AC power supply, 202 filter, 204 transformer.

Claims

1. A power supply system using a plurality of battery module groups each including a plurality of battery modules each having a battery, wherein the batteries in the plurality of battery modules can be connected or disconnected in series with each other based on a gate drive signal from a controller, a pass-through control for eliminating the variation in remaining capacity among the batteries within the battery module group and an imbalance control for eliminating the variation in remaining capacity among the batteries among the battery module groups; A power supply system comprising: a power supply unit for searching for the number of paths of the battery to be disconnected within the battery module group in the pass-through control so as to maximize the amount of charge / discharge power in the battery module group.

2. 2. The power supply system of claim 1, A power supply system characterized by: determining a change in the amount of charge / discharge power in the battery module group when the number of paths is changed while charging / discharging in the battery module group; and searching for the number of paths that maximizes the amount of charge / discharge power in the battery module group from the change in the amount of charge / discharge power.

3. 3. The power supply system according to claim 2, A power supply system, characterized in that the number of paths is changed at the timing when charging and discharging of the battery module group is completed.

4. The power supply system according to any one of claims 1 to 3, The power supply system is characterized in that the process of searching for the number of paths is executed at least one of when the system starts operating, when the battery is replaced, and after a certain period of time has elapsed during system operation.

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