Power management system

Abstract

To enable low-cost detection of reverse connection of the energy storage device on the power conditioner side. [Solution] A power management system (1) is configured such that a diode (204) is connected between the external terminal pair (201) of a power storage device (20) in the direction of current flow when the external terminal pair (201) is connected in reverse to the power storage terminal pair (103) of a power conditioner (10), and the control unit (104) of the power conditioner (10) attempts to output a predetermined verification current from the power storage terminal pair (103) when starting up, and if it detects current flow or voltage drop corresponding to the verification current, it can perform a reverse connection notification process to notify that the external terminal pair and the power storage terminal pair are connected in reverse.

Description

Technical Field

[0001] The present invention relates to a power management system.

Background Art

[0002] A power conditioner that can be connected to a power storage device and perform charging and discharging is known. Such a power conditioner is used, for example, in general residences and on the premises of businesses.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] At the site of the installation work of the power storage device, if the connection polarity between the power storage device and the power conditioner is incorrect, a large current will flow from the reversely connected power storage device to the power conditioner, which may damage the internal circuit of the power conditioner and the storage battery of the power storage device. In Patent Document 1, in order to avoid such a situation, a technology of a power storage device having a function of preventing the storage battery inside the power storage device (power storage unit) from being connected to the power conditioner when reverse connection is detected is disclosed. Thus, the technology disclosed in Patent Document 1 relates to the function of the power storage device. On the other hand, it is also expected to realize a power conditioner that does not require a special circuit to be installed in the power storage device and can detect reverse connection on the power conditioner side at a low cost.

Means for Solving the Problems

[0005] To solve the above problems, one aspect of the present invention provides a power management system comprising: a power storage device having a storage battery and a pair of external terminals electrically connected to the storage battery; a power storage terminal pair for transferring power to and from the power storage device; a power conversion unit electrically connected to the pair of power storage terminals; a measuring unit for measuring the current flowing through the pair of power storage terminals or the voltage applied to the pair of power storage terminals; a notification unit for notifying information; and a control unit, wherein the power storage device has a connection between the pair of external terminals, and the pair of external terminals is connected to the The diode is connected in the direction in which current flows when connected to the energy storage terminal pair in reverse polarity, and the control unit attempts to control the power conversion unit to output a predetermined verification current from the energy storage terminal pair when the power conditioner starts up, and if the measurement unit detects the flow of the current or the voltage drop corresponding to the predetermined verification current as a result, it controls the notification unit to perform a reverse connection notification process that notifies that the external terminal pair and the energy storage terminal pair are connected in reverse polarity.

[0006] The control unit of the power conditioner in each aspect of the power management system according to the present invention may be implemented by one or more computers. In this case, the power conditioner control program that implements the control unit in each computer by causing each computer to operate as a software element of the power conditioner, and a computer-readable recording medium on which the program is recorded, also fall within the scope of the present invention. [Effects of the Invention]

[0007] According to one aspect of the present invention, a power control system equipped with a power conditioner that can detect reverse connection without installing a special circuit in the energy storage device and at low cost can be realized. [Brief explanation of the drawing]

[0008] [Figure 1] This is a functional block diagram showing the main components of a power management system according to an embodiment of the present invention. [Figure 2]This is a circuit diagram showing an overview of the circuit configuration from the power conversion unit of the power conditioner to the energy storage device in a power management system according to an embodiment of the present invention. [Figure 3] This is a circuit diagram showing an overview of the circuit configuration when the power conditioner's energy storage terminal pair and the energy storage device's external terminal pair are connected in reverse polarity in a power management system according to an embodiment of the present invention. [Figure 4] This is a functional block diagram showing the essential components of the comparative example power management system. [Modes for carrying out the invention]

[0009] [Embodiment] <Overview of Power Management System 1> Figure 1 is a functional block diagram showing the main parts of a power management system 1 according to an embodiment of the present invention. The power management system 1 comprises a power conditioner 10 and a power storage device 20. The power conditioner 10 has a pair of power storage terminals 103 for exchanging power with the power storage device 20. The power storage device 20 has a pair of external terminals 201 for exchanging power with the power conditioner 10.

[0010] A power line 30, consisting of DC power cables and the like, electrically connects the pair of energy storage terminals 103 of the power conditioner 10 to the pair of external terminals 201 of the energy storage device 20. Since the installation locations of the power conditioner 10 and the energy storage device 20 vary, the length of the power line 30 connecting the power conditioner 10 and the energy storage device 20 can also vary.

[0011] Below, we will explain the configuration of the power management system 1 in more detail, referring also to Figure 2. Figure 2 is a circuit diagram showing an overview of the circuit configuration from the power conversion unit 101 of the power conditioner 10 to the energy storage device 20 in the power management system 1.

[0012] <Energy storage device 20> The energy storage device 20 includes a battery 203 and the aforementioned pair of external terminals 201 electrically connected to the battery 203. The energy storage device 20 also includes a switch 202 located between the battery 203 and the pair of external terminals 201 in the circuit. The switch 202 has a switch function that allows the battery 203 to be disconnected from the pair of external terminals 201. The switch 202 is configured, for example, using an electromagnetic relay or a semiconductor switch.

[0013] The energy storage device 20 may further have a control circuit (not shown) that controls the switching unit 202. For example, the switching unit 202 may be configured to shut off when it detects an abnormality, such as abnormal overheating of the battery 203 or an abnormal current exceeding the limit of the battery 203. Alternatively, as proposed in Patent Document 1, the switching unit 202 may be configured to shut off when it detects a reverse connection to the power conditioner 10, but this function is not essential.

[0014] As described above, energy storage devices 20 with various specifications, including functions, are manufactured and made available by specialized manufacturers (hereinafter referred to as energy storage device manufacturers). The seller of the power conditioner 10 can select an appropriate energy storage device 20 according to the application and purpose of the power management system 1, for example, in terms of capacity, charge / discharge current rating, etc. In this way, the seller of the power conditioner 10 can provide the user with an appropriate energy storage device 20 in combination with the power conditioner 10 as a power management system 1, according to the user's usage.

[0015] In the power management system 1 according to the embodiment, a diode 204 is further added to the power storage device 20. Specifically, as shown in FIG. 2, the diode 204 is connected between the external terminal pair 201 of the power storage device 20 in the direction in which current flows when the external terminal pair 201 is connected to the power storage terminal pair 103 with the opposite polarity. Here, connecting the diode 204 between the external terminal pair 201 means the same as that the high-potential side terminal (positive terminal) and the low-potential side terminal (negative terminal) constituting the external terminal pair 201 are electrically connected via the diode 204.

[0016] Note that the high-potential side terminal is a terminal connected to the high-potential side of the storage battery 203, and the low-potential side terminal is a terminal connected to the low-potential side of the storage battery 203. Further, the direction in which current flows when the external terminal pair 201 is connected to the power storage terminal pair 103 in the reverse direction means the same as that the anode of the diode 204 is electrically connected to the low-potential side terminal and the cathode is electrically connected to the high-potential side terminal.

[0017] Since the diode 204 is only connected between the external terminal pair 201 of the power storage device 20, when adding such a diode 204 to the power storage device 20, it is not necessary to change the internal configuration of the power storage device 20. Therefore, it can be easily implemented for the seller of the power conditioner 10 to add such a diode 204 to the power storage device 20 provided by the power storage device manufacturer.

[0018] Most simply, one diode component may be physically connected to the high-potential side terminal and the low-potential side terminal, for example, by soldering. However, if it is electrically substantially equivalent, the diode 204 may be connected and arranged at an appropriate location inside the power storage device 20.

[0019] <Power conditioner 10> The power conditioner 10 has at least a power conversion unit 101, a measurement unit 102, the above-mentioned power storage terminal pair 103, a control unit 104, and a notification unit 105. Further, the power conditioner 10 has an AC terminal block 111, an AC / DC conversion unit 112, and a DC bus 110.

[0020] The primary side of the power conversion unit 101 is connected to the DC bus 110, and the secondary side is connected to the power storage terminal pair 103, and power conversion unit 101 conducts DC power transfer with the power storage terminal pair 103. The power conversion unit 101 may be composed of a bidirectional DC / DC converter with an arbitrary circuit configuration. The schematic circuit configuration of the power conversion unit 101 shown in the circuit diagram of FIG. 2 is an example.

[0021] The measurement unit 102 is provided on the circuit between the power conversion unit 101 and the power storage terminal pair 103. The measurement unit 102 measures the current flowing through the power storage terminal pair 103 or the applied voltage. That is, the measurement unit 102 measures the current through which the power conversion unit 101 transfers power to and from the power storage device 20 via the power storage terminal pair 103 or the terminal voltage of the power storage terminal pair 103.

[0022] The control unit 104 is a functional block that executes required information processing and can control each part of the power conditioner 10. For this purpose, the control unit 104 may be configured to exchange information with the power storage device 20. As is well known regarding a system capable of executing information processing, the hardware of the control unit 104 may be physically concentrated in one device, or may be distributed, and in some cases, a part of its function may be configured on the cloud.

[0023] The control unit 104 controls the operation of the power conversion unit 101 using information about at least one of the current or voltage of the energy storage terminal pair 103 measured by the measurement unit 102, and can control the power conditioner 10 to exchange the required power with the energy storage device 20. The notification unit 105 is a functional block that provides information under the control of the control unit 104. The notification unit 105 may be configured to include a display function such as an LED lamp or a liquid crystal panel.

[0024] The power conditioner 10 has an AC terminal block 111 for connecting to a commercial AC power grid 50. The AC terminal block 111 may be for three-phase AC or single-phase AC. An AC / DC converter 112 is provided between the AC terminal block 111 and the DC bus 110. The AC / DC converter 112 may consist of a bidirectional AC-DC converter with any circuit configuration. The commercial AC power grid 50 connected to the AC terminal block 111 may also be connected to loads in, for example, general residences or business premises.

[0025] With the above configuration, the power conditioner 10 can, for example, exchange power with at least one of the above-mentioned load and the commercial AC grid 50 by utilizing the energy storage function of the energy storage device 20. Such operations can be performed, for example, to shift the time of selling electricity from the commercial AC grid 50, or to smooth out fluctuations in the power consumption of the above-mentioned load.

[0026] Furthermore, the power conditioner 10 may also have a pair of PV terminals 123, which are external terminals for connecting solar panels (photovoltaic: PV), and a DC / DC converter 121 provided in the circuit between the DC bus 110 and the pair of PV terminals 123. In this case, the control unit 104 performs power control of the solar panels using the DC / DC converter 121. The DC / DC converter 121 may be composed of a DC / DC converter with any circuit configuration.

[0027] Furthermore, the power conditioner 10 may have an EV terminal pair 133, which is an external terminal for connecting an electric vehicle (EV) charging device, connected to the DC bus 110. Note that the EV terminal pair 133 may not be directly connected to the DC bus 110, but rather configured to be connected to the DC bus 110 via a DC / DC converter of any circuit configuration.

[0028] <Characteristic operation of the power conditioner (reverse connection notification processing)> The power conditioner 10 of the power management system 1 according to this embodiment may perform the following characteristic operation (reverse connection notification processing) when the power conditioner 10 is started up. Here, "may perform reverse connection notification processing" means that the power conditioner 10 can also be configured to cancel the execution of reverse connection notification processing. For example, after the installation of the power management system 1, which combines the power conditioner 10 and the energy storage device 20, has been successfully completed, it is possible to configure the power conditioner 10 to cancel the execution of such reverse connection notification processing.

[0029] When a seller or other party of the power management system 1 installs the power management system 1, which combines a power conditioner 10 and an energy storage device 20, the connection between the energy storage terminal pair 103 and the external terminal pair 201 via the line 30 is completed. After that, the construction worker starts up the power conditioner 10.

[0030] When the power conditioner 10 starts up, the control unit 104 of the power conditioner 10 attempts to control the power conversion unit 101 to output a predetermined verification current from the energy storage terminal pair 103 to the energy storage device 20. That is, the control unit 104 operates the power conversion unit 101 in, for example, constant current mode (CC mode).

[0031] In this case, it is preferable that the predetermined verification current is smaller than the rated current that the power conversion unit 101 outputs to the energy storage device 20 through the energy storage terminal pair 103. That is, it is preferable that the verification current is smaller than the charging current that the power conditioner 10 normally outputs to the energy storage device 20. In this case, a verification current that is sufficiently smaller than the rated current may be obtained by connecting a high-impedance element in series with the power conversion unit 101 and reducing the current value of the charging current output to the energy storage device 20.

[0032] For example, if the rated charging current is several tens of amperes, it is preferable that the magnitude of the verification current be around several hundred mA, which is sufficiently smaller than the rated current. Note that the magnitude of the verification current should be set so as to be a current or voltage value that the measurement unit 102 can reliably detect. It is also preferable that the control unit 104 sets a voltage limit value, i.e., a predetermined upper voltage limit, when controlling the power conversion unit 101 to output a predetermined verification current to the energy storage device 20.

[0033] In other words, the control unit 104 attempts to control the power conversion unit 101 to output a predetermined verification current from the energy storage terminal pair 103 by keeping the terminal voltage of the energy storage terminal pair 103, which is the voltage detected by the measurement unit 102, within a range where it does not reach a predetermined upper limit voltage. It is also preferable that such a voltage limit value is the same as or smaller than the voltage that the power conditioner 10 applies to the energy storage terminal pair 103 when charging the battery 203 of the energy storage device 20.

[0034] The control unit 104 determines whether the power conversion unit 101 can output the predetermined verification current as follows. If the connection between the energy storage terminal pair 103 and the external terminal pair 201 by the line 30 is correct, that is, if the connection work was done in the state shown in the circuit diagram of Figure 2, then the following occurs.

[0035] Since the diode 204 connected between the external terminal pair 201 of the energy storage device 20 is oriented in a way that prevents the confirmation current from flowing, no confirmation current flows. Because the measurement unit 102 cannot detect that a confirmation current is flowing, the control unit 104 attempts to operate the power conversion unit 101 in a direction that increases the output of the power conversion unit 101.

[0036] If a voltage limit value is set, when the measurement unit 102 detects the above voltage limit value (a predetermined upper limit voltage) as the terminal voltage between the energy storage terminal pair 103, the control unit 104 stops the output operation of the power conversion unit 101 by ceasing to supply the verification current. Setting a voltage limit value in this way suppresses the load on the diode 204 to which the reverse bias is applied.

[0037] If no voltage limit is set, the control unit 104 controls the power converter 101 to operate to the point where its output is maximized, while no current flows through the external terminal pair 201. At this point, the control unit 104 stops supplying the verification current and shuts down the output operation of the power converter 101.

[0038] Thus, the control unit 104 recognizes that, as a result of the power conversion unit 101 attempting to output a predetermined verification current from the energy storage terminal pair, the measurement unit 102 was unable to detect the flow of current or voltage drop corresponding to the predetermined verification current.

[0039] On the other hand, if the connection between the energy storage terminal pair 103 and the external terminal pair 201 via the line 30 is not made correctly, that is, if the connection work is done incorrectly so that the polarity of the energy storage terminal pair 103 and the external terminal pair 201 is reversed, as shown in Figure 3, the following will occur.

[0040] The orientation of the diode 204 connected between the external terminal pair 201 of the energy storage device 20 is such that the verification current that the power conversion unit 101 intends to output flows through it. As a result, the verification current flows, and the terminal voltage of the energy storage terminal pair 103 is approximately zero. In this way, the control unit 104 can cause the power conversion unit 101 to output the predetermined verification current.

[0041] In other words, the control unit 104 recognizes that the measurement unit 102 has detected current flow or voltage drop corresponding to the predetermined confirmation current, as a result of the power conversion unit 101 attempting to output a predetermined confirmation current from the energy storage terminal pair. Once the predetermined confirmation current has been confirmed, the control unit 104 stops the output operation of the power conversion unit 101.

[0042] As described above, the control unit 104 can determine whether the connection between the energy storage terminal pair 103 and the external terminal pair 201 via the transmission line 30 was made correctly, or whether the polarity was incorrectly reversed.

[0043] Furthermore, the current flowing from the power conditioner 10 to the diode 204 added to the energy storage device 20 for this purpose is less than or equal to the predetermined verification current. No large current flows through the diode 204, and the load on the diode 204 is small. Therefore, the current rating of the diode 204 added to the energy storage device 20 does not need to be large, and a small element can be used. Thus, the diode 204 can be easily added to the energy storage device 20, and an inexpensive diode 204 can be used.

[0044] If the power conversion unit 101 attempts to output the predetermined verification current from the energy storage terminal pair 103, and the measurement unit 102 detects the flow of current or a voltage drop corresponding to the predetermined verification current, the control unit 104 performs the following operation. That is, if the connection work was done incorrectly, the control unit 104 performs the following operation.

[0045] The control unit 104 controls the notification unit 105 to notify that the external terminal pair 201 and the energy storage terminal pair 103 are connected in reverse. Such notification can be performed by appropriate methods, such as flashing a specific LED lamp on the notification unit 105 or sounding a warning. The control unit 104 also prohibits the power conversion unit 101 from performing a charging operation to the energy storage device 20.

[0046] Upon receiving the above notification, the construction worker will shut down the power conditioner 10 without starting the energy storage device 20, and then redo the connection work between the power conditioner 10 and the energy storage device 20.

[0047] In the above explanation, the operation of the power conversion unit 101 in constant current mode (CC mode) was used as an example of an operation to attempt to output a predetermined verification current from the energy storage terminal pair 103 to the energy storage device 20. However, such operation is arbitrary as long as it attempts to output a predetermined verification current to the energy storage device 20, and is not limited to constant current mode (CC mode).

[0048] For example, in constant voltage mode (CV mode), if the voltage limit value mentioned above is set as the voltage to be output and the "predetermined verification current" mentioned above is set as the current limit value, then the reverse connection notification process can be executed in the same manner as in the constant current mode (CC mode) described above.

[0049] <Comparative Example 1> Similar to the power management system 1 according to the embodiment, the configuration of Comparative Example 1, described below, can be considered as a method for detecting incorrect connections from the power conditioner side. Figure 4 is a functional block diagram showing the configuration of the power management system 1C of Comparative Example 1 in comparison with the power management system 1 according to the embodiment. Note that parts having the same function as in the above embodiment are denoted by the same reference numerals, and their descriptions are omitted.

[0050] The energy storage device 20C of the power management system 1C does not have the diode 204 installed in the embodiment. That is, the energy storage device 20C of the comparative example is an energy storage device as provided by the energy storage device manufacturer. The power conditioner 10C of the power management system 1C has a switch 140C on the circuit between the power conversion unit 101 and the measurement unit 102. The switch 140C switches the circuit between the power conversion unit 101 and the energy storage terminal pair 103. The initial state of the switch 140C is the open state, that is, the energy storage terminal pair 103 is disconnected from the power conversion unit 101.

[0051] Before operating the power conversion unit 101, the control unit 104C of the power management system 1C detects whether the terminal voltage of the energy storage terminal pair 103 detected by the measurement unit 102 is in the reverse direction, with the switch 140C open. If the control unit 104C detects that it is in the reverse direction, it controls the notification unit 105C without closing the switch 140C to notify that the external terminal pair 201 and the energy storage terminal pair 103 are connected in the reverse direction.

[0052] As described above, the power conditioner 10C in the comparative example is equipped with a switch 140C, which prevents abnormal current from the energy storage device 20C connected in reverse from flowing into the power conversion unit 101. However, the switch 140C provided for this purpose requires the use of a DC switch, which increases the cost of the power conditioner. Furthermore, the switch 140C is essentially unnecessary except for the purpose of checking for reverse connection when installing the power management system 1C, and providing the switch 140C is not cost-effective.

[0053] On the other hand, in the power management system 1 according to this embodiment, such a switching unit 140C and a special circuit for checking reverse connection in the energy storage device as in Comparative Example 1 are unnecessary, and it can be implemented at low cost.

[0054] <Comparative Example 2> To prevent incorrect connections between power conditioners and energy storage devices during installation work at power management system sites, the use of dedicated connectors at the connection points is envisioned. In other words, each product would be equipped with connectors that cannot be connected in the reverse direction at the power conditioner's energy storage terminal pair, the energy storage device's external terminal pair, and the end of the transmission line (DC power cable), thereby preventing errors during on-site connection.

[0055] However, this method is practically unfeasible for the following reasons. As mentioned above, the required length of the transmission line 30 varies depending on the installation location of the power conditioner 10 and the energy storage device 20, making it difficult to prepare commercially available transmission lines (DC power cables) of the appropriate length in advance. In addition, transmission lines are often routed through conduits, and if connectors are already attached to the ends of the transmission lines, the wiring work becomes difficult.

[0056] [Examples of implementation using software] The functions of the control unit 104 (hereinafter referred to as the "device") can be realized by a program that causes the device to function as a computer. In this case, the device includes at least one computer having at least one control device (e.g., a processor) and at least one storage device (e.g., memory) as hardware for executing the program.

[0057] By executing the above program using this control device and storage device, the functions described in each of the above embodiments are realized. The above program may be recorded on one or more computer-readable recording media, not temporary. This recording media may or may not be provided by the above device. In the latter case, the above program may be supplied to the above device via any wired or wireless transmission medium. [Explanation of symbols]

[0058] 1. Power Management System 10 Power Conditioner 101 Power Conversion Unit 102 Measuring section 103 Terminal pair for energy storage 104 Control Unit 105 Hochi Department 110 DC bus 111 AC terminal block 112 AC / DC Conversion Section 20 Energy storage devices 201 External terminal pair 202 Opening / Closing Section 203 Storage Battery 204 diode 30 railroad tracks

Claims

1. A power management system comprising: a power storage device having a battery and a pair of external terminals electrically connected to the battery; a power conditioner having a pair of power storage terminals for transferring power to and from the power storage device, a power conversion unit electrically connected to the pair of power storage terminals, a measuring unit for measuring the current flowing through the pair of power storage terminals or the voltage applied to them, a notification unit for notifying information, and a control unit; The aforementioned energy storage device has a diode connected between the external terminal pair in the direction in which current flows when the external terminal pair is connected with the energy storage terminal pair in opposite polarity. The control unit, when the power conditioner is started, The power conversion unit is controlled to output a predetermined verification current from the energy storage terminal pair, and as a result, the measurement unit detects the flow of the current or the voltage drop corresponding to the predetermined verification current, A power management system capable of controlling the notification unit to perform a reverse connection notification process, which notifies that the external terminal pair and the energy storage terminal pair are connected in reverse polarity.

2. The power management system according to claim 1, wherein the predetermined verification current is a current smaller than the rated current that the power conversion unit outputs to the energy storage device through the energy storage terminal pair.

3. The power management system according to claim 1 or 2, wherein the control unit attempts to control the power conversion unit to output a predetermined verification current from the power storage terminal pair within a range in which the measurement unit detects the voltage and the voltage does not reach a predetermined upper limit voltage.

4. The power management system according to claim 2, wherein the predetermined verification current is a current smaller than the rated current due to the charging current output to the energy storage device passing through a high-impedance element connected in series with the power conversion unit.

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