JP7666602B2 - Charging equipment - Google Patents

Description

The present disclosure relates to a charging device.

The secondary battery (storage battery) installed in a plug-in hybrid vehicle (hereinafter referred to as a PHEV (Plug-in Hybrid Electric Vehicle)) or an electric vehicle (hereinafter referred to as an EV (Electric Vehicle)) is charged by an external power source (external charger). In recent years, vehicle-mounted storage batteries have become more capable of handling high voltages, and there is a movement to promote chargers with higher voltages (e.g., 800V) (hereinafter referred to as 800V chargers) rather than the currently mainstream chargers (e.g., chargers with a charging voltage of 400V (hereinafter referred to as 400V chargers)). During the transitional period, it is expected that chargers with multiple charging voltages (400V and 800V) will be mixed in the city.

The following Patent Document 1 discloses an energy storage system capable of switching between a series connection and a parallel connection of multiple batteries. When switching from a series connection to a parallel connection of multiple batteries, this energy storage system can balance the voltages of multiple batteries while avoiding the occurrence of losses and shortening of the life of the contacts. Specifically, referring to FIG. 1, the energy storage system 401 includes batteries BT1 and BT2, relays RY1 to RY7 and 28, an on-board charger 20 as a power converter, and a control circuit 45. An external charger is connected to the external charging connection units 11 and 12. AC power is supplied to the AC power connection units 16 and 17 from an external commercial power source. The relays RY1 to RY3 can switch the connection state of the batteries BT1 and BT2 between series and parallel. The positive and negative poles of the battery BT1 are connected to the input/output port P1 of the on-board charger 20, and the positive and negative poles of the battery BT2 are connected to the input/output port P2. The on-board charger 20 converts AC power supplied from a commercial power source to the AC power supply connectors 16 and 17 into DC power and charges the batteries BT1 and BT2. The on-board charger 20 also transfers power between the batteries BT1 and BT2. The control circuit 45 controls the relays RY1 to RY7 and the on-board charger 20. Before switching the batteries BT1 and BT2 to a parallel connection, the control circuit 45 performs a voltage balancing process to operate the on-board charger 20 so that the potential difference between the batteries BT1 and BT2 is equal to or less than a predetermined threshold, and then turns on the relays RY1 and RY3. The relay 28 opens and closes the path between the batteries BT1 and BT2 and the on-board charger 20. The load 80 is, for example, a device that is generally used in an electric vehicle or a plug-in hybrid vehicle.

JP 2019-80473 A

A charging device according to one aspect of the present disclosure includes a power path that supplies power output from an on-board charger to M cells for a first storage battery among N storage battery cells connected in series, and a power converter that converts the power output from the on-board charger, where N is an integer of 2 or more and M is an integer of 1 or more, and the power converter supplies the converted power to M cells for a second storage battery among the N storage battery cells.

FIG. 1 is a block diagram showing the configuration of an electricity storage system capable of charging two batteries by switching between a series connection and a parallel connection. FIG. 2 is a block diagram showing a configuration of a power storage system according to an embodiment of the present disclosure. FIG. 3 is a circuit diagram showing an example of the configuration of two storage batteries. FIG. 4 is a block diagram showing a state in which two storage batteries are charged by an on-board charger in the power storage system shown in FIG. FIG. 5 is a block diagram showing a configuration for supplying power from the second storage battery to the first storage battery. FIG. 6 is a block diagram showing a configuration of a power storage system according to a first modified example. FIG. 7 is a block diagram showing a configuration of a power storage system according to a second modified example. FIG. 8 is a block diagram showing a configuration of a power storage system according to a third modified example.

[Problem to be solved by the present disclosure]
In a situation where two types of chargers, a 400V charger and an 800V charger, are mixed, it is preferable to be able to charge with either the 400V charger or the 800V charger. To achieve this, as disclosed in Patent Document 1, it is possible to use a plurality of switching relays. That is, when two storage batteries are charged with an 800V charger, the switching relay is set so that the two storage batteries are connected in series, and charging is performed. On the other hand, when two storage batteries are charged with a 400V charger, the switching relay is set so that the two storage battery modules are connected in parallel, and charging is performed.

However, when a switching relay between series and parallel connections is used, the following problems arise. First, when the vehicle is running, the storage batteries are connected in series to supply high voltage to the inverter of the driving motor, so current also flows through the switching relay, resulting in power loss. Second, the switching relay may fail, and depending on the state of the failure, driving operation may be hindered. Third, when switching between series and parallel connections, a short-circuit current flows, resulting in power loss. To prevent short-circuit current from flowing, it is necessary to perform processes such as equalizing the voltages of the storage batteries before connecting them in parallel, which is cumbersome. The charging voltage is not limited to two types, 400V and 800V.

In order to solve the above problem, it is possible to use two storage batteries connected in series at all times. However, with the currently popular on-board chargers, it is not possible to charge the two storage batteries while they are connected in series. For example, when two 400V storage batteries are connected in series, the voltage across both ends (hereinafter referred to as the series voltage) is 800V. Therefore, these storage batteries cannot be charged with an on-board charger (hereinafter referred to as the 400V on-board charger) that can convert a commercial power source (e.g., AC 100V) and output a charging voltage (DC) of 400V. It is necessary to newly develop an on-board charger (hereinafter referred to as the 800V on-board charger) that can output a charging voltage of 800V. Even if 800V on-board chargers will be installed in vehicles in the future, it is preferable in terms of cost and stable supply if a 400V on-board charger can be used.

Therefore, the present disclosure aims to provide a charging device that enables multiple storage batteries connected in series to be charged by an on-board charger that outputs a charging voltage lower than the series voltage.

[Effects of the present disclosure]
According to the present disclosure, it is possible to provide a charging device that enables a plurality of storage batteries connected in series to be charged by an on-board charger that outputs a charging voltage lower than the series voltage.

[Description of the embodiments of the present disclosure]
The contents of the embodiments of the present disclosure will be listed and described below. At least a part of the embodiments described below may be arbitrarily combined.

(1) A charging device according to a first aspect of the present disclosure includes a power path that supplies power output from an on-board charger to M cells for a first storage battery among N storage battery cells connected in series, and a power converter that converts the power output from the on-board charger, where N is an integer of 2 or more and M is an integer of 1 or more, and the power converter supplies the converted power to M cells for a second storage battery among the N storage battery cells. This allows the M cells for the first storage battery and the M cells for the second storage battery connected in series to be charged by the on-board charger that outputs a charging voltage lower than the series voltage.

(2) Preferably, the first storage battery and the second storage battery are interconnected by a common node, the power path includes a first power path connecting a first terminal of the two output terminals of the vehicle charger to the common node, and a second power path connecting a second terminal of the two output terminals of the vehicle charger to a first node that is a node of the first storage battery and the second storage battery that is a node other than the common node, and a third terminal of the two output terminals of the power converter is connected to the common node, and a fourth terminal of the two output terminals of the power converter is connected to a second node that is a node of the first storage battery and the second storage battery that is a node other than the common node and the first node. This allows the vehicle charger to be appropriately connected to the M cells for the first storage battery and the M cells for the second storage battery that are connected in series, increasing the freedom of arrangement.

(3) More preferably, the charging device further includes N storage battery cells connected in series and an on-board charger. This allows the M cells for the first storage battery and the M cells for the second storage battery connected in series to be charged by the on-board charger with a charging voltage lower than the series voltage.

(4) More preferably, the charging device transfers power between the first storage battery and the second storage battery via a power converter. This makes it possible to equalize the amount of electricity stored in the multiple storage batteries. Therefore, when power is supplied to a load from multiple storage batteries connected in series, it is possible to avoid a situation in which the power of only some of the storage batteries becomes zero, resulting in an inability to supply power overall.

(5) Preferably, the power converter is a multi-port power converter that outputs power to two or more systems. This makes it possible to supply power to multiple loads, etc., with different voltage specifications.

[Details of the embodiment of the present disclosure]
In the following embodiments, the same parts are denoted by the same reference numerals, and their names and functions are also the same, so detailed description thereof will not be repeated.

(composition)
2, the power storage system 100 according to the embodiment of the present disclosure includes an on-board charger 102, a power converter 104, power paths 130, 132, 134, and 136, a first storage battery 902, and a second storage battery 904. The power storage system 100 may be mounted on a vehicle such as a PHEV or an EV. Terminals 112 and 114 are connected to an input section of the on-board charger 102, and the first storage battery 902 and the second storage battery 904 are charged as described below by connecting a commercial power source to the terminals 112 and 114. Hereinafter, charging using AC power from a commercial power source is referred to as AC charging. A charging device for AC charging the first storage battery 902 and the second storage battery 904 is configured by elements other than the first storage battery 902, the second storage battery 904, and the on-board charger 102 among the components of the power storage system 100.

The first storage battery 902 and the second storage battery 904 are connected in series, and the connection portion forms a first common node 930. The first storage battery 902 and the second storage battery 904 are chargeable and dischargeable storage batteries (lithium ion batteries, etc.) of the same specifications. Each of the first storage battery 902 and the second storage battery 904 is composed of a storage battery. In this disclosure, the term "storage battery" is used to mean one storage battery cell, multiple storage battery cells, one storage battery module (package of multiple storage battery cells), and multiple storage battery modules. For example, as shown in FIG. 3, the first storage battery 902 and the second storage battery 904 may be configured by dividing N storage battery cells 140 (N is an integer of 2 or more) connected in series into two equal numbers (M (M is an integer of 1 or more)). For example, the first common node 930 is provided in a storage battery module 142 of 800V specifications. The plurality of storage battery cells between the node 932 and the first common node 930 are cells for the first storage battery 902 (i.e., cells that function as the first storage battery 902). The plurality of storage battery cells between the first common node 930 and the node 934 are cells for the second storage battery 904 (i.e., cells that function as the second storage battery 904). Here, each of the first storage battery 902 and the second storage battery 904 is assumed to be of 400V specification (the rated charging voltage and output voltage are 400V). Note that each node is at the same potential as the corresponding terminal among the terminals (positive terminal and negative terminal) of the first storage battery 902 and the second storage battery 904, and connection to a node means connection to the terminals of the first storage battery 902 and the second storage battery 904.

Figure 2 shows a switching unit 914 (switches 916 and 918) and terminals 940 and 942 required for charging the first storage battery 902 and the second storage battery 904 by an off-vehicle charger. The first storage battery 902 and the second storage battery 904 are charged by connecting the output terminals of the off-vehicle charger to terminals 940 and 942. Figure 2 also shows a load 906 to which power is supplied from the first storage battery 902 and the second storage battery 904.

The on-board charger 102 is an AC/DC converter that converts AC power input from terminals 112 and 114 into DC power and outputs it. AC power (e.g., 100V or 200V, etc.) is supplied to the on-board charger 102 from a commercial power source. Specifically, a connector of a connection cable connected to a commercial power source is attached to a socket including terminals 112 and 114, and AC power is input to the terminals 112 and 114. The on-board charger 102 generates and outputs DC power from the input AC power under the control of, for example, an ECU (Electronic Control Unit) (not shown). Here, as described above, each of the first storage battery 902 and the second storage battery 904 is a 400V specification, so the output voltage of the on-board charger 102 is 400V.

The output terminal OUT1 of the vehicle charger 102 is connected to the first common node 930 via a power path 130. The power path 130 refers to a power line connecting the output terminal OUT1 and the first common node 930. The output terminal OUT2 of the vehicle charger 102 is connected to a node 932 via a power path 132. The power path 132 refers to a power line connecting the output terminal OUT2 and the node 932.

The power converter 104 is an insulated DC/DC converter and includes a transformer (not shown). The power converter 104 includes terminals 120, 122, 124, and 126. The power converter 104 includes a bridge circuit composed of switching elements between the terminals 120 and 122 and the primary coil of the transformer, and between the terminals 124 and 126 and the secondary coil of the transformer. The switching elements may be FETs (Field Effect Transistors) or IGBTs (Insulated Gate Bipolar Transistors), and the bridge circuit may be a full bridge circuit or a half bridge circuit. The power converter 104 generates DC power from the DC power input to the terminals 120 and 122 under the control of the control unit 110, and outputs the DC power from the terminals 124 and 126. The output voltage of the power converter 104 is the same magnitude as the input voltage to the power converter 104. Since the output voltage of the on-board charger 102 is 400V, the input voltage and output voltage of the power converter 104 are 400V.

Terminal 120 is connected to output terminal OUT1 of on-board charger 102 via power path 134 (power path 134 is connected to power path 130). Power path 134 refers to a power line connecting output terminal OUT1 and terminal 120. Terminal 122 is connected to output terminal OUT2 of on-board charger 102 via power path 136 (power path 136 is connected to power path 132). Power path 136 refers to a power line connecting output terminal OUT2 and terminal 122. Terminal 124 is connected to power path 130 and is also connected to first common node 930. Terminal 126 is connected to node 934.

The charging information input to the control unit 110 may include information on the voltage of quick charging and information on AC charging. If the charging information includes information instructing the execution of AC charging, the control unit 110 controls the power conversion operation of the power converter 104. Specifically, the control unit 110 controls the on and off of the switching elements included in the power converter 104, so that the power converter 104 functions as a DC/DC converter that outputs a voltage of the same magnitude as the input voltage as described above. Note that, during quick charging, the control unit 110 controls the switching of the switches 916 and 918 according to the charging information. The switch 916 switches between a state in which the terminal 940 is connected to the node 932 and a state in which the terminal 940 is connected to the first common node 930 under the control of the control unit 110. The switch 918 switches between a state in which the terminal 942 is connected to the first common node 930 and a state in which the terminal 942 is connected to the node 934 under the control of the control unit 110.

(AC charging operation)
In the case of AC charging, when the on-board charger 102 outputs a DC voltage (400 V) from the output terminals OUT1 and OUT2 under the control of the ECU, the output voltage of the on-board charger 102 is supplied between the first common node 930 and the node 932. This charges the first storage battery 902. In addition, the output voltage of the on-board charger 102 is converted by the power converter 104 and supplied between the first common node 930 and the node 934. This charges the second storage battery 904. The charging current at this time is indicated by the dashed arrow in FIG. 4. In this way, in the power storage system 100, the first storage battery 902 and the second storage battery 904, which are connected in series, can be charged simultaneously by the power output from the on-board charger 102.

(Power transfer between storage batteries)
Even if the first storage battery 902 and the second storage battery 904 are the same type (e.g., the same product number), when AC charging is performed as described above, an imbalance may occur in the amount of charge stored in the first storage battery 902 and the second storage battery 904 due to variations in the characteristics of each individual battery. For example, a case may be considered in which the amount of charge stored in the first storage battery 902 is lower than the amount of charge stored in the second storage battery 904. In such a state, when power is supplied from the first storage battery 902 and the second storage battery 904 to the load 906, the power of the first storage battery 902 becomes zero first, and power cannot be supplied to the load 906 even though power remains in the second storage battery 904. The same is true when the amount of charge stored in the second storage battery 904 is lower than the amount of charge stored in the first storage battery 902. Therefore, it is preferable to equalize the amounts of charge stored in the first storage battery 902 and the second storage battery 904 before supplying power to the load 906 from the first storage battery 902 and the second storage battery 904. In order for the power storage system 100 to have the function of equalizing the amount of stored power in the first storage battery 902 and the second storage battery 904, the power converter 104 needs to be a bidirectional DC/DC converter.

As described above, the power converter 104 is an isolated DC/DC converter, and under the control of the control unit 110, generates DC power from the DC power input to the terminals 120 and 122, and outputs it from the terminals 124 and 126. The power converter 104 is further controlled by the control unit 110, generates DC power from the DC power input to the terminals 124 and 126 (output power of the second storage battery 904), and outputs it from the terminals 120 and 122. As a result, a current flows as shown by the dashed line in FIG. 5, and the power of the second storage battery 904 can be transmitted to the first storage battery 902 to charge the first storage battery 902. Since the power converter 104 is an isolated DC/DC converter, the potential difference between both terminals of the first storage battery 902 and the potential difference between both terminals of the second storage battery 904 are both maintained at normal values.

For example, before supplying power from the first storage battery 902 and the second storage battery 904 to the load 906, the control unit 110 acquires the SOC (State of Charge) representing the charging rate (%) of the first storage battery 902 and the second storage battery 904. If the absolute value (difference) of the value obtained by subtracting the SOC of the first storage battery 902 from the SOC of the second storage battery 904 is equal to or greater than a predetermined value, the control unit 110 operates the power converter 104 so that the difference becomes less than the predetermined value, and supplies power from the storage battery with the larger SOC to the storage battery with the smaller SOC. This makes it possible to avoid a situation in which, for example, the amount of charge in the first storage battery 902 becomes zero first, and power cannot be supplied to the load 906 even though power remains in the second storage battery 904. Therefore, more power can be supplied for a longer period of time than when power is not supplied from the second storage battery 904 to the first storage battery 902.

(effect)
As described above, the charging device includes power paths 130 and 132 that supply power output from the on-board charger 102 to the first storage battery 902 of the two storage batteries connected in series, and the power converter 104 that converts the DC power output from the on-board charger 102. The power converter 104 supplies the converted power to the second storage battery 904 of the two storage batteries. This allows the first storage battery 902 and the second storage battery 904 connected in series to be charged by the on-board charger that outputs a charging voltage (e.g., 400 V) lower than the series voltage (e.g., 800 V).

As described above, the power converter 104 is an isolated DC/DC converter. The voltage of the power after conversion by the power converter 104 (e.g., 400 V) is the same as the voltage of the power output from the vehicle charger (e.g., 400 V). This allows the first storage battery 902 and the second storage battery 904, which are connected in series, to be charged simultaneously.

As described above, the first storage battery 902 and the second storage battery 904 are interconnected by a common node (first common node 930). The power path includes a first power path (power path 130) that connects a first terminal (output terminal OUT1) of the two output terminals OUT1 and OUT2 of the vehicle charger 102 to the common node. The power path also includes a second power path (power path 132) that connects a second terminal (output terminal OUT2) of the two output terminals of the vehicle charger 102 to a first node (node 932) that is a node other than the common node among the nodes of the first storage battery 902 and the second storage battery 904. The third terminal (terminal 124) of the two output terminals of the power converter 104 is connected to the common node (first common node 930). Of the two output terminals of the power converter 104, a fourth terminal (terminal 126) is connected to a second node (node 934) that is a node different from the common node and the first node among the nodes of the first storage battery 902 and the second storage battery 904. This allows the on-board charger and the multiple storage batteries connected in series to be appropriately connected, increasing the freedom of arrangement.

The charging device may further include a first switch arranged on the power path 130 and a second switch arranged on the power path 132. The first switch and the second switch switch between an open state (off) and a closed state (on) under the control of the control unit 110. The first switch and the second switch may be a mechanical relay or a semiconductor relay. The first switch and the second switch are in a closed state when the first storage battery 902 and the second storage battery 904 are charged by the on-board charger 102, and are in an open state when the first storage battery 902 and the second storage battery 904 are charged by the off-vehicle charger. This makes it possible to protect the on-vehicle charger 102 when the first storage battery 902 and the second storage battery 904 are charged by the off-vehicle charger.

(First Modification)
In the above, a configuration has been described in which, during AC charging in the power storage system 100 (see FIG. 2 ), the first storage battery 902 is directly charged by the output power of the on-board charger 102, and the second storage battery 904 is charged via the power converter 104. However, the present invention is not limited to this. A configuration may also be used in which, during AC charging, the second storage battery 904 is directly charged by the output power of the on-board charger 102, and the first storage battery 902 is charged via the power converter 104.

Referring to Figure 6, the energy storage system 150 according to the first modified example is obtained by modifying the arrangement of the power converter 104 and its connection to the surroundings in the energy storage system 100 shown in Figure 2. In Figure 6, components with the same reference numerals as in Figure 2 have the same functions as in Figure 2. Therefore, without repeating the explanation, the following mainly describes the points where the energy storage system 150 differs from the energy storage system 100.

In the power storage system 150, the output terminal OUT1 of the on-board charger 102 is connected to the node 934 via the power path 152. The output terminal OUT2 of the on-board charger 102 is connected to the first common node 930 via the power path 130. That is, the power path 130 means a power line connecting the output terminal OUT1 and the first common node 930, and the power path 152 means a power line connecting the output terminal OUT2 and the node 934. The terminal 124 of the on-board charger 102 is connected to the node 932 of the first storage battery 902, and the terminal 126 is connected to the first common node 930. The terminals 120 and 122 of the power converter 104 are connected to the output terminals OUT2 and OUT1 of the on-board charger 102 via the power paths 134 and 136, respectively. That is, the power path 134 refers to the power line connecting the output terminal OUT1 and the terminal 120, and the power path 136 refers to the power line connecting the output terminal OUT2 and the terminal 122.

During AC charging, when the on-board charger 102 outputs a DC voltage (400V) from output terminals OUT1 and OUT2 under the control of the ECU, the output voltage of the on-board charger 102 is supplied between the first common node 930 and node 934. This charges the second storage battery 904. In addition, the output voltage of the on-board charger 102 is converted by the power converter 104 and supplied between the first common node 930 and node 932. This charges the first storage battery 902. In this way, in the energy storage system 150, the first storage battery 902 and the second storage battery 904, which are connected in series, can be charged simultaneously by the power output from the on-board charger 102.

In the storage system 150 according to the first modified example, as described above, the first storage battery 902 and the second storage battery 904 are interconnected by a common node (first common node 930). The power path includes a first power path (power path 130) that connects a first terminal (output terminal OUT2) of the two output terminals OUT1 and OUT2 of the vehicle charger 102 to the common node. The power path also includes a second power path (power path 152) that connects a second terminal (output terminal OUT1) of the two output terminals of the vehicle charger 102 to a first node (node 934) that is a node other than the common node among the nodes of the first storage battery 902 and the second storage battery 904. The third terminal (terminal 126) of the two output terminals of the power converter 104 is connected to the common node (first common node 930). Of the two output terminals of the power converter 104, a fourth terminal (terminal 124) is connected to a second node (node 932) which is a node other than the common node and the first node among the nodes of the first storage battery 902 and the second storage battery 904. This allows the on-board charger and the multiple storage batteries connected in series to be appropriately connected, increasing the freedom of arrangement.

(Second Modification)
In the above, a configuration has been described in which two storage batteries are connected in series and charged simultaneously using an on-board charger that outputs a voltage corresponding to the charging voltage of one storage battery, but this is not limiting. Three or more storage batteries connected in series may be charged. The power storage system according to the second modification has three storage batteries connected in series as charging targets.

With reference to FIG. 7, the power storage system 160 according to the second modification is the power storage system 100 shown in FIG. 2, to which a third storage battery 162, a second common node 164, and a power converter 166 are added, and the switching unit 914 and the control unit 110 are replaced with a switching unit 170 and a control unit 180, respectively. The switching unit 170 is the switching unit 914 (FIG. 2) to which switches 172 and 174 are added. The third storage battery 162 has the same specifications (e.g., 400V specifications) as the first storage battery 902 and the second storage battery 904. The switch 172 is connected to the first common node 930 formed by connecting the first storage battery 902 and the second storage battery 904 in series. The switch 174 is connected to the second common node 164 formed by connecting the second storage battery 904 and the third storage battery 162 in series. In FIG. 7, components with the same reference numerals as those in FIG. 2 have the same functions as those in FIG. 2. Therefore, redundant description will not be repeated, and the following description will mainly focus on the differences between power storage system 160 and power storage system 100.

The input section of the power converter 104 is connected to the output terminals OUT1 and OUT2 of the on-board charger 102 via power paths 134 and 136, similar to the energy storage system 100. The output section of the power converter 104 is connected to the first common node 930 and the second common node 164, unlike the energy storage system 100.

The power converter 166 is an isolated DC/DC converter similar to the power converter 104, and includes a transformer and a bridge circuit composed of switching elements. The input section of the power converter 166 is connected to the output terminals OUT1 and OUT2 of the vehicle charger 102 via the power paths 134 and 136. The output section of the power converter 166 is connected to the second common node 164 and the node 934. Under the control of the control unit 180, the power converter 166 generates and outputs DC power from the DC power input from the vehicle charger 102. The output voltage of the power converter 166 is the same as the input voltage of the power converter 166. Since the output voltage of the vehicle charger 102 is 400V, the input voltage and output voltage of the power converter 166 are 400V.

Similar to control unit 110, control unit 180 receives charging information, controls each switch, and controls power converter 104. Control unit 180 further controls power converter 166. That is, control unit 180 controls the on and off of switching elements included in power converter 166, so that power converter 166 functions as a DC/DC converter that outputs a voltage the same as the input voltage, as described above.

In the case of AC charging, when the on-board charger 102 outputs a DC voltage (400V) from the output terminals OUT1 and OUT2 under the control of the ECU, the output power of the on-board charger 102 is supplied between the first common node 930 and the node 932, thereby charging the first storage battery 902. In addition, the output voltage of the on-board charger 102 is converted by the power converter 104 and supplied between the first common node 930 and the second common node 164. In this way, the second storage battery 904 is charged. In addition, the output voltage of the on-board charger 102 is converted by the power converter 166 and supplied between the second common node 164 and the node 934. In this way, the third storage battery 162 is charged. The charging current at this time is indicated by the dashed arrow in FIG. 7. In this way, in the power storage system 160, the first storage battery 902, the second storage battery 904, and the third storage battery 162 connected in series can be charged simultaneously by the power output from the on-board charger 102.

In addition, in the configuration of FIG. 7, if each of the power converter 104 and the power converter 166 is a bidirectional DC/DC converter, power can be supplied between any two of the first storage battery 902, the second storage battery 904, and the third storage battery 162 to make the storage amount the same. At this time, since each of the power converter 104 and the power converter 166 is an insulated DC/DC converter, the potential difference between both terminals of the first storage battery 902, the potential difference between both terminals of the second storage battery 904, and the potential difference between both terminals of the third storage battery 162 are all maintained at normal values. Therefore, when power is supplied to a load from multiple storage batteries connected in series, it is possible to avoid a situation in which the power of only some of the storage batteries becomes zero, resulting in the inability to supply power as a whole.

(Third Modification)
Although the above describes a case where the power converter 104 has one output unit, the present invention is not limited to this. In the power storage system according to the third modification, the power converter has a plurality of output units.

With reference to Figure 8, the energy storage system 190 according to the third modified example is the energy storage system 100 shown in Figure 2, in which the power converter 104 and the control unit 110 are replaced with a multi-port power converter 192 and a control unit 198, respectively, and modified so that power can be supplied from the second storage battery 904 to the first storage battery 902 and the low-voltage auxiliary equipment 204 via the multi-port power converter 192. In Figure 8, components with the same reference numerals as in Figure 2 have the same functions as in Figure 2. Therefore, without repeating the explanation, the following mainly describes the differences from the energy storage system 100.

The input port 194 of the multi-port power converter 192 is connected to nodes corresponding to both terminals of the second storage battery 904. That is, the input port 194 is connected to the node 934 and the first common node 930. The output port 196 of the multi-port power converter 192 can output high and low voltage DC voltages (e.g., 400V and 12V). The terminal of the output port 196 that outputs the high voltage DC voltage (400V) is connected to both terminals of the first storage battery 902 (the first common node 930 and the node 932) via the power paths 134 and 136. The terminal of the output port 196 that outputs the low voltage DC voltage (12V) is connected to both terminals of the low voltage auxiliary equipment 204. The low voltage auxiliary equipment 204 is an auxiliary equipment necessary for operating the engine and motor of the vehicle, and mainly includes a starter motor, an alternator, a radiator cooling fan, etc. The low voltage accessories 204 may include lighting, wiper drives, navigation devices, air conditioning, heaters, etc.

The multi-port power converter 192 includes, for example, a transformer having one primary coil (input side) and two secondary coils (output side), and a bridge circuit configured with switching elements connected to each of the primary coil and two secondary coils of the transformer. The switching elements include, for example, FETs or IGBTs. The bridge circuit includes, for example, a full bridge circuit or a half bridge circuit. For example, the control unit 198 controls the switching elements constituting the bridge circuit to be turned on and off with a control signal of a predetermined frequency, thereby converting the DC voltage input to the primary coil of the transformer, generating DC voltages of different magnitudes, and outputting them from the two secondary coils. That is, a current flows as shown by the dashed arrow in FIG. 8, and the power supplied from the second storage battery 904 to the input port 194 can be transmitted to the output port 196 and supplied to the first storage battery 902 and the low-voltage auxiliary equipment 204. This allows power to be supplied to the first storage battery 902 and the low-voltage auxiliary equipment 204, which have different voltage specifications.

The present disclosure has been described above by explaining the embodiments, but the above-mentioned embodiments are merely examples, and the present disclosure is not limited to only the above-mentioned embodiments. The scope of the present disclosure is indicated by each claim in the scope of claims, taking into consideration the description of the detailed description of the invention, and includes all modifications within the meaning and scope equivalent to the wording described therein.

11, 12 External charging connection unit 16, 17 AC power supply connection unit 20, 102 Vehicle charger 28, RY1, RY2, RY3, RY4, RY5, RY6, RY7 Relay 45 Control circuit 80, 906 Load 100, 150, 160, 190, 401 Storage system 104, 166 Power converter 110, 180, 198 Control unit 112, 114, 120, 122, 124, 126, 940, 942 Terminal 130, 132, 134, 136, 152 Power path 140 Storage battery cell 142 Storage battery module 162 Third storage battery 164 Second common node 170, 914 Switching unit 172, 174, 916, 918 Switch 192 Multi-port power converter 194 Input port 196 Output port 204 Low voltage auxiliary machine 902 First storage battery 904 Second storage battery 930 First common nodes 932, 934 Nodes BT1, BT2 Batteries OUT1, OUT2 Output terminals P1, P2 Input/output port

Claims (5)

a power path that supplies power output from an on-board charger to M cells for a first storage battery among the N storage battery cells connected in series;
a power converter that converts the power output from the on-board charger,
The N is an integer of 2 or more,
The M is an integer of 1 or more,
The charging device, wherein the power converter supplies converted power to the M cells for a second storage battery among the N storage battery cells. the first storage battery and the second storage battery are interconnected by a common node;
The power path is
a first power path connecting a first terminal of two output terminals of the on-board charger to the common node;
a second power path that connects a second terminal of the two output terminals of the on-board charger to a first node that is a node of the first storage battery and the second storage battery, the first node being a node other than the common node;
a third terminal of the two output terminals of the power converter is connected to the common node;
2. The charging device according to claim 1, wherein a fourth terminal of the two output terminals of the power converter is connected to a second node which is a node other than the common node and the first node among the nodes of the first storage battery and the second storage battery. The N storage battery cells connected in series;
The charging device according to claim 1 or 2, further comprising the on-board charger. A charging device as described in any one of claims 1 to 3, wherein power is exchanged between the first storage battery and the second storage battery via the power converter. The charging device according to any one of claims 1 to 4, wherein the power converter is a multi-port power converter that outputs power to two or more systems.

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