Charge and discharge test system, charge and discharge test method, and control device

Abstract

Provided are a charge and discharge test system, a charge and discharge test method, and a control device capable of reducing power loss associated with conversion of power charged and discharged by a charge and discharge body. A charge and discharge system 1 comprises: an AC / DC converter 20 that converts first power into second DC power; a bidirectional DC / DC converter 30 that has one end connected to the AC / DC converter 20 via a bus BS, has the other end connected to a charge and discharge body BT to be subjected to a charge and discharge test, and converts second DC power converted by the AC / DC converter 20 into third DC power or converts power discharged by the charge and discharge body BT into the second DC power; a capacitor 40 connected to the bus BS; and a control device 10 that controls at least one operation of the AC / DC converter 20 and the bidirectional DC / DC converter 30.

Description

Charge / discharge test system, charge / discharge test method, and control device

[0001] The present disclosure relates to a charge / discharge test system, a charge / discharge test method, and a control device.

[0002] In recent years, hybrid vehicles, plug-in hybrid vehicles, and electric vehicles have become popular. These vehicles are equipped with traction batteries. For example, Patent Document 1 discloses technology related to a charge / discharge test system for connecting and testing a plurality of these batteries. In this charge / discharge test system, a plurality of circuits including a bidirectional DC / DC converter and charge / discharge devices are connected in parallel to a bus that supplies DC power. In this charge / discharge test system, a test target charge / discharge device charges and discharges power according to its own test schedule, while a non-test target charge / discharge device charges and discharges power in accordance with the test of the test target charge / discharge device.

[0003] JP 2023-10581 A

[0004] However, in the method disclosed in Patent Document 1, when power discharged from a charging / discharging device under test is charged to a non-testing charging / discharging device, power conversion is performed twice by the bidirectional DC / DC converter, resulting in power loss associated with the conversion. Similarly, when power discharged from a non-testing charging / discharging device is charged to a testing charging / discharging device, power conversion is performed twice by the bidirectional DC / DC converter, resulting in power loss associated with the conversion. Therefore, with conventional technology, it has been difficult to reduce power loss associated with conversion when sharing power between charging / discharging devices included in a charge / discharge test system.

[0005] A charge / discharge test system that solves the above problem includes a converter that converts a first power into a second DC power, a bidirectional DC / DC converter that has one end connected to the converter via a bus and the other end connected to a charge / discharge device that is the subject of a charge / discharge test, and that converts the second DC power converted by the converter into a third DC power or converts the power discharged by the charge / discharge device into the second DC power, a capacitor connected to the bus, and a control device that controls the operation of at least one of the converter and the bidirectional DC / DC converter.

[0006] A charge / discharge test method that solves the above problem includes a converter that converts first power into second DC power, a bidirectional DC / DC converter that has one end connected to the converter via a bus and the other end connected to a charge / discharge device that is the subject of a charge / discharge test, and that converts the second DC power converted by the converter into third DC power or converts the power discharged by the charge / discharge device into the second DC power, and a capacitor connected to the bus. A computer that realizes a control device for a charge / discharge test system controls the operation of at least one of the converter and the bidirectional DC / DC converter.

[0007] A control device that solves the above problem is a control device for a charge / discharge test system that includes a converter that converts first power into second DC power, a bidirectional DC / DC converter that has one end connected to the converter via a bus and the other end connected to a charge / discharge device that is the subject of a charge / discharge test, and that converts the second DC power converted by the converter into third DC power or converts the power discharged by the charge / discharge device into the second DC power, and a capacitor connected to the bus, and that controls the operation of at least one of the converter and the bidirectional DC / DC converter.

[0008] According to the present disclosure, it is possible to reduce power loss associated with conversion of power charged and discharged by a charging / discharging body.

[0009] Fig. 1 is a diagram illustrating an example of the configuration of a charging / discharging system. Fig. 2 is a flowchart illustrating an example of processing executed by a control device. Fig. 3 is a diagram illustrating another example of the configuration of a charging / discharging system. Fig. 4 is a diagram used to explain switches provided on a bus.

[0010] Embodiments Hereinafter, embodiments of a charge / discharge test system, a charge / discharge test method, and a control device will be described with reference to the drawings.

[0011] [Overall Configuration] As shown in FIG. 1, the charge / discharge system 1 includes a control device 10, an AC / DC converter 20, one or more bidirectional DC / DC converters 30, a capacitor 40, an electronic load 50, a voltage detection unit 60, and a bus BS.

[0012] The AC / DC converter 20 has, for example, one end connected to an AC power source E1 and the other end connected to the bus BS. The AC power source E1 is, for example, system power. The power supplied by the AC power source E1 is, for example, AC power, specifically, commercial 100V or commercial 200V AC power. Based on the control of the control device 10, the AC / DC converter 20 converts the AC power supplied by the AC power source E1 into predetermined DC power and supplies this DC power to the bus BS. The power supplied by the AC power source E1 is an example of a "first power." The predetermined DC power supplied by the AC / DC converter 20 to the bus BS is an example of a "second DC power."

[0013] The bidirectional DC / DC converter 30 has, for example, one end connected to the bus BS and the other end connected to a charging / discharging body BT under test. The charging / discharging body BT is a test subject for a charging / discharging test using the charging / discharging system 1. The charging / discharging body BT is, for example, a variety of known secondary batteries such as lithium-ion batteries, nickel-metal hydride batteries, and all-solid-state batteries (as well as other power-storing devices including large-capacity capacitors such as electric double layer batteries). Based on the control of the control device 10, the bidirectional DC / DC converter 30 converts a predetermined DC power supplied to the bus BS into DC power that can be charged by the charging / discharging body BT and supplies this DC power to the charging / discharging body BT. Based on the control of the control device 10, the bidirectional DC / DC converter 30 also converts power discharged by the charging / discharging body BT into a predetermined DC power and supplies this DC power to the bus BS. The DC power converted by the bidirectional DC / DC converter 30 and that can be charged by the charging / discharging body BT is an example of a "third DC power."

[0014] The charge / discharge system 1 includes bidirectional DC / DC converters 30, the number of which corresponds to the number of charge / discharge bodies BT that can be tested by the charge / discharge system 1. In this embodiment, a case will be described in which the charge / discharge system 1 includes one bidirectional DC / DC converter 30. In the following description, the predetermined DC power supplied to the bus BS will be referred to as bus power, and the DC voltage generated on the bus BS will be referred to as bus voltage V.

[0015] A capacitor 40 is connected to the bus BS. The capacitor 40 is realized by various known secondary batteries such as lithium-ion batteries, nickel-metal hydride batteries, and all-solid-state batteries (or other devices capable of storing power, including large-capacity capacitors such as electric double layer batteries). The capacitor 40 charges bus power or discharges the charged power to the bus BS depending on the state of the bus BS and its own charge / discharge state. The capacity of the capacitor 40 is determined based on, for example, the maximum output performance of the bidirectional DC / DC converter 30 included in the charge / discharge system 1.

[0016] An electronic load 50 is connected to the bus BS. The electronic load 50 operates under the control of the control device 10. The electronic load 50 operates as a pseudo load that consumes bus power. The electronic load 50 is an example of a "power consumption unit."

[0017] The bus BS is provided with a voltage detection unit 60 that detects a bus voltage V. The voltage detection unit 60 detects the bus voltage V and outputs information indicating the detected bus voltage V to the control device 10. The control device 10 is realized, for example, by a programmable logic controller (PLC). The control device 10 controls at least one of the AC / DC converter 20 and the bidirectional DC / DC converter 30 based on the bus voltage V detected by the voltage detection unit 60. Specifically, the control device 10 controls at least one of the AC / DC converter 20 and the bidirectional DC / DC converter 30 so that the bus BS maintains an appropriate bus voltage V.

[0018] More specifically, the control device 10 determines which of six states the charging / discharging system 1 is in based on the bus voltage V, and controls at least one of the AC / DC converter 20 and the bidirectional DC / DC converter 30 based on the determined state. The six states are, for example, a low voltage state, a high voltage state, a load operation recommended state, a conversion stop recommended state, a conversion suppression recommended state, and a maximum conversion recommended state. Each state will be described in detail below.

[0019] [Low Voltage State] When the bus voltage V detected by the voltage detection unit 60 is lower than the low voltage abnormality voltage Ve, the control device 10 determines that the charging / discharging system 1 is in a low voltage state. Here, the AC / DC converter 20 may be unable to perform an appropriate conversion operation for some reason. In this case, the AC / DC converter 20 experiences a low voltage abnormality. A low voltage abnormality occurs when the voltage output by the AC / DC converter 20 is lower than the normal voltage. The low voltage abnormality voltage Ve indicates the output voltage of the AC / DC converter 20 when a low voltage abnormality occurs. When the control device 10 determines that the charging / discharging system 1 is in a low voltage state, it stops the charging / discharging system 1. Specifically, the control device 10 stops the operation of the AC / DC converter 20 and the bidirectional DC / DC converter 30.

[0020] [High-Voltage State] The control device 10 determines that the charging / discharging system 1 is in a high-voltage state when the bus voltage V detected by the voltage detection unit 60 is equal to or greater than the abnormal high-voltage voltage Va. The abnormal high-voltage voltage Va is the operating voltage of the electronic load 50. Specifically, the abnormal high-voltage voltage Va indicates the bus voltage V in a state where the bus voltage V cannot be reduced to an appropriate voltage even when the electronic load 50 consumes bus power through its operation. The abnormal high-voltage voltage Va is, for example, a predetermined value based on the performance of the electronic load 50. When the control device 10 determines that the charging / discharging system 1 is in a high-voltage state, it stops the operation of the bidirectional DC / DC converter 30. This stops the bidirectional DC / DC converter 30 from converting and supplying to the bus BS the power generated by the discharge of the charging / discharging body BT, causing the bus voltage V to drop.

[0021] [Regarding the Load Operation Recommended State] The control device 10 determines that the charging / discharging system 1 is in a load operation recommended state when the bus voltage V detected by the voltage detection unit 60 is less than the high-voltage abnormality voltage Va and equal to or greater than the load operation voltage Vb. The load operation voltage Vb indicates the bus voltage V that has been reduced as the electronic load 50 consumes bus power through its operation. The load operation voltage Vb is a value that is predetermined based on, for example, the performance of the electronic load 50. When the control device 10 determines that the charging / discharging system 1 is in a load operation recommended state, it operates the electronic load 50. As a result, the bus power is consumed by the electronic load 50, and the bus voltage V decreases. The load operation voltage Vb is an example of the "operating voltage of the power consumption unit."

[0022] [Regarding the Conversion Stop Recommended State] The control device 10 determines that the charging / discharging system 1 is in a conversion stop recommended state when the bus voltage V detected by the voltage detection unit 60 is less than the load operating voltage Vb and greater than or equal to the maximum output voltage Vc. The maximum output voltage Vc indicates the maximum DC voltage output by the AC / DC converter 20. The maximum output voltage Vc is a predetermined value based on, for example, the performance of the AC / DC converter 20. When the control device 10 determines that the charging / discharging system 1 is in a conversion stop recommended state, the control device 10 stops the AC / DC converter 20. Note that the control device 10 does not operate the electronic load 50 in the conversion stop recommended state. As a result, the bus voltage V decreases due to internal consumption within the charging / discharging system 1 while the supply of power from the AC / DC converter 20 is stopped. The maximum output voltage Vc is an example of a "reference voltage."

[0023] Specifically, when the charging / discharging body BT is in a charging state, the bidirectional DC / DC converter 30 converts the power stored in the capacitor 40 and supplies the converted power to the charging / discharging body BT. If the bus voltage V for the bidirectional DC / DC converter 30 is high, the power conversion efficiency of the bidirectional DC / DC converter 30 deteriorates. In the conversion stop recommended state, the AC / DC converter 20 is stopped, causing a predetermined amount of power to be charged to the charging / discharging body BT. As a result, the bus power is consumed, and the bus voltage V decreases. Furthermore, when the charging / discharging body BT is in a discharging state, the bidirectional DC / DC converter 30 converts the power discharged by the charging / discharging body BT and charges the converted power to the capacitor 40 via the bus BS. Because the bus voltage V for the bidirectional DC / DC converter 30 is high, the bidirectional DC / DC converter 30 is required to increase the voltage of the power output to the bus BS. This deteriorates the power conversion efficiency of the bidirectional DC / DC converter 30. Therefore, as bus power is consumed to charge the capacitor 40 with a predetermined amount of power, the bus voltage V decreases.

[0024] [Regarding the Conversion Suppression Recommended State] The control device 10 determines that the charging / discharging system 1 is in the conversion suppression recommended state when the bus voltage V detected by the voltage detection unit 60 is less than the maximum output voltage Vc and greater than or equal to the normal output voltage Vd. The normal output voltage Vd indicates the output voltage output by the AC / DC converter 20 under normal conditions. The normal output voltage Vd is a predetermined value based on, for example, the performance of the AC / DC converter 20. When the control device 10 determines that the charging / discharging system 1 is in the conversion suppression recommended state, the control device 10 suppresses the conversion operation of the AC / DC converter 20. Specifically, in the conversion suppression recommended state, the control device 10 controls the AC / DC converter 20 so that the DC power output by the AC / DC converter 20 is smaller than the DC power output by the AC / DC converter 20 under normal conditions. Note that the control device 10 does not operate the electronic load 50 in the conversion suppression recommended state. As a result, the bus voltage V decreases due to internal consumption within the charging / discharging system 1 while the power supply from the AC / DC converter 20 is suppressed. The normal output voltage Vd is an example of a "reference voltage."

[0025] Specifically, in the conversion suppression recommended state, the capacitor 40 has been charged with power discharged by the charge / discharge body BT. Therefore, when the charge / discharge body BT is in a charging state, the bidirectional DC / DC converter 30 converts the power supplied from the AC / DC converter 20 and supplies the converted power to the charge / discharge body BT. At this time, the bus voltage V for the bidirectional DC / DC converter 30 is high, which deteriorates the power conversion efficiency of the bidirectional DC / DC converter 30. Therefore, as bus power is consumed to charge the charge / discharge body BT to a predetermined power, the bus voltage V decreases. Furthermore, when the charge / discharge body BT is in a discharging state, the bidirectional DC / DC converter 30 converts the power discharged by the charge / discharge body BT and charges the converted power to the capacitor 40 via the bus BS. At this time, the bus voltage V for the bidirectional DC / DC converter 30 is high, which requires the bidirectional DC / DC converter 30 to increase the voltage of the power output to the bus BS. This deteriorates the power conversion efficiency of the bidirectional DC / DC converter 30. Therefore, as bus power is consumed to charge the capacitor 40 with a predetermined amount of power, the bus voltage V decreases.

[0026] [Maximum Conversion Recommended State] The control device 10 determines that the charging / discharging system 1 is in the maximum conversion recommended state when the bus voltage V detected by the voltage detection unit 60 is lower than the normal output voltage Vd and equal to or higher than the low voltage abnormality voltage Ve. When the control device 10 determines that the charging / discharging system 1 is in the maximum conversion recommended state, the control device 10 controls the AC / DC converter 20 so that the AC / DC converter 20 outputs the maximum current that it can output. Note that the control device 10 does not operate the electronic load 50 in the maximum conversion recommended state. As a result, the bus voltage V increases due to internal consumption within the charging / discharging system 1 while the AC / DC converter 20 supplies maximum power.

[0027] Specifically, when the charging / discharging body BT is in a charging state, the bidirectional DC / DC converter 30 converts the power supplied from the AC / DC converter 20 and supplies the converted power to the charging / discharging body BT. At this time, the bus BS is supplied with sufficient power from the AC / DC converter 20 compared to the power charged by the charging / discharging body BT, so the bus voltage V increases. Also, in the maximum conversion recommended state, the capacitor 40 has already discharged the power charged by the charging / discharging body BT. Therefore, when the charging / discharging body BT is in a discharging state, the bidirectional DC / DC converter 30 converts the power discharged by the charging / discharging body BT and charges the converted power to the capacitor 40 via the bus BS. At this time, the bus BS is supplied with sufficient power from the AC / DC converter 20 in addition to the power discharged by the charging / discharging body BT, so the bus voltage V increases.

[0028] [Regarding Processing Executed by the Control Device 10] A series of processing executed by the control device 10 will be described with reference to Fig. 2. The processing of the flowchart shown in Fig. 2 is repeatedly executed at predetermined time intervals.

[0029] First, the control device 10 determines whether the bus voltage V detected by the voltage detection unit 60 is lower than the low-voltage abnormality voltage Ve (step S100). If the control device 10 determines that the bus voltage V is lower than the low-voltage abnormality voltage Ve (step S100; YES), the control device 10 determines that the charging / discharging system 1 is in a low-voltage state, stops the operation of the AC / DC converter 20, and stops the operation of the bidirectional DC / DC converter 30 (step S102), and ends the series of processes.

[0030] When the control device 10 determines that the bus voltage V is not less than the low-voltage abnormality voltage Ve (step S100; NO), it determines whether the bus voltage V is equal to or greater than the high-voltage abnormality voltage Va (step S104).When the control device 10 determines that the bus voltage V is equal to or greater than the high-voltage abnormality voltage Va (step S104; YES), it determines that the charging / discharging system 1 is in a high-voltage state, and stops the operation of the bidirectional DC / DC converter 30 (step S106), thereby ending the series of processes.

[0031] When the control device 10 determines that the bus voltage V is not equal to or greater than the high-voltage abnormality voltage Va (step S104; NO), it determines whether the bus voltage V is less than the high-voltage abnormality voltage Va and equal to or greater than the load operation voltage Vb (step S108).When the control device 10 determines that the bus voltage V is less than the high-voltage abnormality voltage Va and equal to or greater than the load operation voltage Vb (step S108; YES), it determines that the charging / discharging system 1 is in a load operation recommended state, and operates the electronic load 50 (step S110), thereby ending the series of processes.

[0032] If the control device 10 determines that the bus voltage V is neither less than the high-voltage abnormality voltage Va nor greater than the load operation voltage Vb (step S108; NO), it determines whether the bus voltage V is less than the load operation voltage Vb and greater than or equal to the maximum output voltage Vc (step S112).If the control device 10 determines that the bus voltage V is less than the load operation voltage Vb and greater than or equal to the maximum output voltage Vc (step S112; YES), it determines that the charging / discharging system 1 is in a state where conversion stop is recommended, and stops the AC / DC converter 20 (step S114), ending the series of processes.Note that in step S114, if the electronic load 50 is operating, the control device 10 stops the electronic load 50.

[0033] If the control device 10 determines that the bus voltage V is neither less than the load operating voltage Vb nor greater than the maximum output voltage Vc (step S112; NO), it determines whether the bus voltage V is less than the maximum output voltage Vc and greater than or equal to the normal output voltage Vd (step S116). If the control device 10 determines that the bus voltage V is less than the maximum output voltage Vc and greater than or equal to the normal output voltage Vd (step S116; YES), it determines that the charging / discharging system 1 is in a conversion suppression recommended state, suppresses the conversion operation of the AC / DC converter 20 (step S118), and ends the series of processes. Note that in step S118, if the electronic load 50 is operating, the control device 10 stops the electronic load 50.

[0034] If the control device 10 determines that the bus voltage V is neither less than the maximum output voltage Vc nor greater than the normal output voltage Vd (step S116; NO), that is, if the bus voltage V is less than the normal output voltage Vd and greater than or equal to the low voltage abnormality voltage Ve, it determines that the charging / discharging system 1 is in a maximum conversion recommended state and controls the AC / DC converter 20 to output the maximum current that the AC / DC converter 20 can output (step S122), and terminates the series of processes.

[0035] [Effects of the Embodiments] According to the above-described embodiment, the following effects can be obtained. (1) The charge / discharge system 1 includes an AC / DC converter 20, a bidirectional DC / DC converter 30, a capacitor 40, and a control device 10. The AC / DC converter 20 converts AC power into predetermined DC power. The bidirectional DC / DC converter 30 has one end connected to the AC / DC converter 20 via a bus BS and the other end connected to a charge / discharge body BT that is the subject of a charge / discharge test, and converts the predetermined DC power converted by the AC / DC converter 20 into DC power that can be charged by the charge / discharge body BT. The bidirectional DC / DC converter 30 also converts power discharged by the charge / discharge body BT into the predetermined DC power. The capacitor 40 is connected to the bus BS. The control device 10 controls the operation of at least one of the AC / DC converter 20 and the bidirectional DC / DC converter 30.

[0036] In a conventional charging / discharging system, charged / discharged power may be exchanged between a charging / discharging body BT connected to a bidirectional DC / DC converter and another charging / discharging body connected to another bidirectional DC / DC converter. However, in this case, the power discharged by one charging / discharging body is converted twice by the bidirectional DC / DC converter before being charged by the other charging / discharging body, which may result in power loss due to the conversion.

[0037] According to the configuration of this embodiment, the power discharged by the charge / discharge body BT is converted by the bidirectional DC / DC converter 30 and then charged by the capacitor 40, while the power discharged by the capacitor 40 is converted by the bidirectional DC / DC converter 30 and then charged by the charge / discharge body BT. Therefore, it is possible to reduce power loss associated with the conversion of power charged and discharged by the charge / discharge body BT.

[0038] (2) An electronic load 50 that consumes the supplied power is connected to the bus BS. When the bus voltage V generated on the bus BS is equal to or higher than the maximum output voltage Vc or the normal output voltage Vd, which are reference voltages for the bus voltage V, the control device 10 limits the operation of the AC / DC converter 20 and does not operate the electronic load 50. With this configuration, when the bus voltage V is equal to or higher than the reference voltage, the charging / discharging system 1 limits the operation of the AC / DC converter 20 (for example, by stopping or suppressing operation), thereby promoting a decrease in the bus voltage V and suppressing the consumption of bus power by the electronic load 50.

[0039] (3) When the bus voltage V is lower than the load operation voltage Vb and equal to or higher than the maximum output voltage Vc, the control device 10 stops the operation of the AC / DC converter 20. With this configuration, the charging / discharging system 1 can maintain the bus voltage V at an appropriate level by reducing the bus voltage V as bus power is consumed to charge the charging / discharging body BT or the capacitor 40.

[0040] (4) When the bus voltage V is less than the maximum output voltage Vc and equal to or greater than the normal output voltage Vd, the control device 10 suppresses the conversion operation of the AC / DC converter 20. Specifically, the control device 10 controls the AC / DC converter 20 so that the DC power output by the AC / DC converter 20 is smaller than the DC power output by the AC / DC converter 20 under normal conditions. With this configuration, the charging / discharging system 1 can maintain the bus voltage V at an appropriate level by reducing the bus voltage V as bus power is consumed to charge the charging / discharging body BT or the capacitor 40.

[0041] (5) When the bus voltage V generated at the bus BS is less than the normal output voltage Vd and equal to or greater than the low-voltage abnormality voltage Ve, the control device 10 operates the AC / DC converter 20 so that the output of the AC / DC converter 20 becomes the maximum current. With this configuration, the charging / discharging system 1 can maintain the bus voltage V appropriately by increasing the bus voltage V when sufficient power is supplied from the AC / DC converter 20 to the bus BS compared to the power charged by the charging / discharging body BT. Furthermore, the charging / discharging system 1 can maintain the bus voltage V appropriately by increasing the bus voltage V when sufficient power is supplied from the AC / DC converter 20 to the bus BS in addition to the power discharged by the charging / discharging body BT.

[0042] (6) An electronic load 50 that consumes the supplied power is connected to the bus BS. The control device 10 stops the operation of the bidirectional DC / DC converter 30 when the bus voltage V generated on the bus BS is equal to or higher than the high-voltage abnormality voltage Va. With this configuration, the charging / discharging system 1 can maintain the bus voltage V at an appropriate level by lowering the bus voltage V when the bidirectional DC / DC converter 30 stops converting the power generated by the discharge of the charging / discharging body BT and supplying it to the bus BS.

[0043] (7) When the bus voltage V generated on the bus BS is lower than the low-voltage abnormality voltage Ve, the control device 10 stops the AC / DC converter 20 and the bidirectional DC / DC converter 30. With this configuration, the charging / discharging system 1 can appropriately stop the operation of the charging / discharging system 1 when the AC / DC converter 20 cannot perform an appropriate conversion operation for some reason.

[0044] The above-described embodiments may be modified as follows. The above-described embodiments and the following alternative examples may be combined with each other to the extent that no technical contradiction occurs. The charging / discharging system 1 may include, for example, a DC / AC converter 70 that converts bus power into predetermined AC power. The predetermined AC power is, for example, commercial 100V or commercial 200V AC power.

[0045] Fig. 3 shows an example of the configuration of a charge / discharge system 1 including two DC / AC converters 70-1 and 70-2. The charge / discharge system 1 shown in Fig. 3 also includes two bidirectional DC / DC converters 30-1 and 30-2, with a charge / discharge body BT connected to the bidirectional DC / DC converter 30-1 and a charge / discharge body BT installed in a constant temperature bath CT connected to the bidirectional DC / DC converter 30-2.

[0046] One end of the DC / AC converter 70-1 is connected to the bus BS, and the other end is connected to the control device 10. The DC / AC converter 70-1 supplies the converted predetermined AC power to the control device 10. The control device 10 operates on the predetermined AC power. The DC / AC converter 70-2 has one end connected to the bus BS, and the other end connected to the thermostatic chamber CT. The thermostatic chamber CT operates on the predetermined AC power. The thermostatic chamber CT also changes the temperature inside the thermostatic chamber CT as appropriate in accordance with the test schedule of the charge / discharge element BT set therein.

[0047] According to this configuration, the charging / discharging system 1 can supply power from bus power to operate each component (e.g., control device 10) provided in the charging / discharging system 1 or each component (e.g., constant temperature bath CT) used in testing the charging / discharging system 1.

[0048] 3, the charge / discharge system 1 may further include an AC / DC converter 20-2 (not shown). In this case, for example, one end of the AC / DC converter 20-2 is connected to the AC power source E1, and the other end is connected to each component included in the charge / discharge system 1 or each component used for testing the charge / discharge system 1. In this case, even when bus power is not supplied to the bus BS in the low voltage state described above, the AC / DC converter 20-2 can continuously operate the components that use AC power among the components included in the charge / discharge system 1 or the components used for testing the charge / discharge system 1.

[0049] As shown in FIG. 4 , the bus BS may be provided with a switch SW1 that switches the AC / DC converter 20 and the bidirectional DC / DC converter 30 between a connected state in which they are electrically connected and a disconnected state in which they are not electrically connected. The switch SW1 includes, for example, a first terminal t1 and a second terminal t2. The second terminal t2 of the switch SW1 is directly connected to the AC / DC converter 20. The first terminal t1 of the switch SW2 is connected to the bidirectional DC / DC converter 30 via the bus BS. The switch SW1 also includes a diode. The anode of the diode is connected to the second terminal t2, and the cathode of the diode is connected to the first terminal t1. For example, a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) is used for the switch SW1. Therefore, even in the disconnected state, the switch SW1 allows current to flow from the second terminal t2 to the first terminal t1.

[0050] In this case, the control device 10 connects the switch SW1 when the charging / discharging body BT is in a charging state. The control device 10 also disconnects the switch SW1 when the charging / discharging body BT is in a discharging state. With this configuration, the charging / discharging system 1 can prevent a high bus voltage V from being applied to the output terminal of the AC / DC converter 20 when the bus voltage V increases as the charging / discharging body BT is discharged when the charging / discharging body BT is in a discharging state.

[0051] 4 , the bus BS may be provided with a switch SW2 that switches the capacitor 40 and the bidirectional DC / DC converter 30 between a connected state in which they are electrically connected and a disconnected state in which they are not electrically connected. The switch SW2 has a configuration similar to that of the switch SW1, and therefore a description thereof will be omitted. In this example, the switch SW2 is provided at a position between the bidirectional DC / DC converter 30 and a connection point between the capacitor 40 and the electronic load 50 on the bus BS. The second terminal t2 of the switch SW2 is connected to the capacitor 40 via the bus BS. The first terminal t1 of the switch SW2 is connected to the bidirectional DC / DC converter 30 via the bus BS. Even in the disconnected state, the switch SW2 allows a current to flow from the second terminal t2 to the first terminal t1.

[0052] In this case, the control device 10 disconnects the switch SW2 when the charging / discharging body BT is in a charging state. Furthermore, the control device 10 connects the switch SW2 when the charging / discharging body BT is in a discharging state. With this configuration, the charging / discharging system 1 can charge the capacitor 40 with the power discharged by the charging / discharging body BT, and use the power discharged by the capacitor 40 for other components connected to the bus BS. Examples of other components include components included in the charging / discharging system 1 (e.g., the control device 10) and components used for testing the charging / discharging system 1 (e.g., a thermostatic chamber CT (not shown)). In this case, components unrelated to the charging / discharging system 1 may be connected to the bus BS. These components operate, for example, using a predetermined DC power.

[0053] The AC / DC converter 20 included in the charge / discharge system 1 may be realized by a bidirectional AC / DC converter. With this configuration, the bidirectional AC / DC converter can convert excess bus power into AC power in the high-voltage state, the load operation recommended state, and the conversion stop recommended state, and return this AC power to the AC power source E1. In a facility where the charge / discharge system 1 is installed, other components may use the AC power source E1 in addition to the charge / discharge system 1. Therefore, the charge / discharge system 1 can supply AC power to the other components that use the AC power source E1. Furthermore, the charge / discharge system 1 can sell AC power to the electric power utility that provides the AC power source E1.

[0054] The charging / discharging system 1 may include a bidirectional AC / DC converter instead of (or in addition to) the capacitor 40 and the electronic load 50. In this case, one end of the bidirectional AC / DC converter is connected to the AC power source E1 and the other end is connected to the bus BS. In this case, when the capacitor 40 is charging and when the electronic load 50 is operating, the control device 10 controls the bidirectional AC / DC converter to convert bus power to AC power and return the AC power to the AC power source E1. Furthermore, when the capacitor 40 is discharging, the control device 10 controls the bidirectional AC / DC converter to convert the AC power to a predetermined DC power. Note that when the capacitor 40 is discharging, the control device 10 may cause at least one of the AC / DC converter 20 and the bidirectional AC / DC converter to perform power conversion to convert AC power to a predetermined DC power. With this configuration, the charging / discharging system 1 can omit the capacitor 40 and the electronic load 50.

[0055] The charging / discharging system 1 may include a DC / DC converter between the AC / DC converter 20 and the bidirectional DC / DC converter 30. In this case, one end of the DC / DC converter is connected to the AC / DC converter 20, and the other end is connected to the bus BS. The DC / DC converter converts the DC power converted by the AC / DC converter 20 into predetermined DC power (i.e., bus power). Here, the DC power converted by the AC / DC converter 20 may not be suitable as bus power. With this configuration, the DC / DC converter can convert the DC power converted by the AC / DC converter 20 into appropriate bus power. In this case, the DC power supplied by the AC / DC converter 20 is an example of "first power." The predetermined DC power supplied by the DC / DC converter to the bus BS is an example of "second DC power."

[0056] The control device 10 may be realized, for example, by a hardware processor such as a CPU (Central Processing Unit) executing a program (software). Furthermore, some or all of the components of the control device 10 may be realized by hardware (including circuitry) such as an LSI (Large Scale Integration), an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a GPU (Graphics Processing Unit), or may be realized by a combination of software and hardware. The program may be stored in advance in a storage device (not shown) equipped with a non-transitory storage medium such as an HDD (Hard Disk Drive) or flash memory that is included in the control device 10.

[0057] The bus BS may be provided with a resistor instead of the electronic load 50. In this case, the bus BS is provided with a switch that switches the bus BS and the resistor between a connected state in which they are electrically connected and a disconnected state in which they are not electrically connected. The control device 10 controls the switch to control the bus BS and the resistor to a connected state or a disconnected state. In this case, the control device 10 operating the electronic load 50 is equivalent to the control device 10 controlling the switch to a connected state. Furthermore, the control device 10 stopping the electronic load 50 is equivalent to the control device 10 controlling the switch to a disconnected state. In this case, the combination of the resistor and the switch is an example of a "power consumption unit."

[0058] The capacitance of the capacitor 40 may be determined based on a charge / discharge schedule for the charge / discharge body BT instead of (or in addition to) the maximum output performance of the bidirectional DC / DC converter 30 .

[0059] - As used herein, the expression "at least one of A and B" means "A only, B only, or both A and B."

[0060] 1...Charge / discharge system, 10...Control device, 20, 20-1, 20-2...AC / DC converter, 30, 30-1, 30-2...Bidirectional DC / DC converter, 40...Capacitor, 50...Electronic load, 60...Voltage detection unit, 70, 70-1, 70-2...DC / AC converter, BS...Bus, BT...Charge / discharge body, CT...Constant temperature bath, E1...AC power source, SW1, SW2...Switch, V...Bus voltage, Va...Voltage when high voltage is abnormal, Vb...Voltage when load is operating, Vc...Maximum output voltage, Vd...Normal output voltage, Ve...Voltage when low voltage is abnormal.

Claims

1. A charge / discharge test system comprising: a converter that converts a first power into a second DC power; a bidirectional DC / DC converter having one end connected to the converter via a bus and the other end connected to a charge / discharge device that is the subject of a charge / discharge test, and that converts the second DC power converted by the converter into a third DC power or converts the power discharged by the charge / discharge device into the second DC power; a capacitor connected to the bus; and a control device that controls the operation of at least one of the converter and the bidirectional DC / DC converter.

2. The charge / discharge test system according to claim 1, wherein a power consumption unit that consumes the supplied power is connected to the bus, and the control device does not operate the power consumption unit while restricting the operation of the converter when a bus voltage generated on the bus is higher than a reference voltage of the bus voltage.

3. The charge / discharge test system according to claim 2, wherein the control device stops operation of the converter when the bus voltage is lower than the operating voltage (Vb) of the power consumption unit and is equal to or higher than the maximum voltage that the converter can output.

4. The charge / discharge test system according to claim 2, wherein the control device reduces the output current of the converter compared to normal current when the bus voltage is less than the maximum voltage that the converter can output and is equal to or greater than the output voltage of the converter under normal conditions.

5. The charge / discharge test system according to claim 1, wherein the control device operates the converter so that the output of the converter becomes the maximum current when the bus voltage generated on the bus is lower than the output voltage of the converter under normal conditions and is equal to or higher than the output voltage of the converter under a low voltage abnormality.

6. The charge / discharge test system according to claim 1, wherein a power consumption unit that consumes the supplied power is connected to the bus, and the control device stops operation of the bidirectional DC / DC converter when a bus voltage generated on the bus is equal to or higher than an operating voltage of the power consumption unit.

7. The charge / discharge test system according to claim 1, wherein the control device stops the converter and the bidirectional DC / DC converter when the bus voltage generated on the bus is lower than the output voltage of the converter during a low voltage abnormality.

8. The charge / discharge test system according to claim 1, wherein the bus is provided with a switch for switching the converter and the bidirectional DC / DC converter between a connected state in which they are electrically connected and a disconnected state in which they are not electrically connected, and the control device switches the switch to the connected state when the charge / discharge device is in a charging state, and switches the switch to the disconnected state when the charge / discharge device is in a discharging state.

9. The charge / discharge test system according to claim 1, wherein the bus is provided with a switch that switches between a connected state in which the capacitor and the bidirectional DC / DC converter are electrically connected and a disconnected state in which they are not electrically connected, and the control device switches the switch to the disconnected state when the charge / discharge body is in a charging state, and switches the switch to the connected state when the charge / discharge body is in a discharging state.

10. A charge / discharge test method, in which a computer implementing a control device for a charge / discharge test system includes a converter that converts first power into second DC power, a bidirectional DC / DC converter connected at one end to the converter via a bus and at the other end to a charge / discharge device that is the subject of a charge / discharge test, and that converts the second DC power converted by the converter into third DC power or converts power discharged by the charge / discharge device into the second DC power, and a capacitor connected to the bus, controls the operation of at least one of the converter and the bidirectional DC / DC converter.

11. A control device for a charge / discharge test system comprising: a converter that converts first power into second DC power; a bidirectional DC / DC converter having one end connected to the converter via a bus and the other end connected to a charge / discharge device that is the subject of a charge / discharge test, and that converts the second DC power converted by the converter into third DC power or converts power discharged by the charge / discharge device into the second DC power; and a capacitor connected to the bus, wherein the control device controls the operation of at least one of the converter and the bidirectional DC / DC converter.

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