Voltage converter

Abstract

To provide a technique of capable of securely detecting an output excess state of a converter.SOLUTION: A voltage converter has a voltage converter, a connection terminal, a relay, and a controller. An electric power source is connected to an input end of the voltage converter. A load receiving power supply from the voltage converter is connected to the connection terminal. The relay is connected between an output end of the voltage converter and the connection terminal. The controller controls the voltage converter and the relay. The controller opens the relay and issues a command to the voltage converter so as to set output end voltage of the voltage as converter target voltage. When the output end voltage exceeds a predetermined excess voltage determination threshold value higher than the target voltage in the state, the controller outputs a signal indicating abnormality of the voltage converter.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The technology disclosed in this specification relates to a voltage conversion device. [Background technology]

[0002] Patent Document 1 discloses a voltage conversion device. The voltage conversion device includes a converter that converts voltage and a controller that controls the converter. The controller monitors the output terminal voltage of the converter. When the output terminal voltage exceeds a predetermined overvoltage determination threshold, the controller transmits status information indicating the state of the converter to a higher-level ECU. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2022-188516 A Summary of the Invention [Problem to be solved by the invention]

[0004] The controller of the voltage conversion device disclosed in Patent Document 1 monitors the output voltage of the converter when a load (a device that receives power from the converter) is connected to the converter. If the current consumption of the connected load is large, the output current may flow to the load even if the converter is in an excessive output state, and the output voltage of the converter may not exceed the overvoltage determination threshold. In other words, there is a risk that the controller may not be able to detect the excessive output state of the converter. This specification provides a technology that can reliably detect the excessive output state of the converter. [Means for solving the problem]

[0005] The voltage conversion device disclosed in this specification includes a voltage converter, a connection terminal, a relay, and a controller. A power source is connected to the input terminal of the voltage converter. A load that receives power from the voltage converter is connected to the connection terminal. The relay is connected between the output terminal of the voltage converter and the connection terminal. The voltage converter and the relay are controlled by a controller. The controller opens the relay and issues a command to the voltage converter to set the output terminal voltage of the voltage converter to a target voltage. In this state, when the output terminal voltage exceeds a predetermined overvoltage determination threshold higher than the target voltage, the controller outputs a signal indicating an abnormality in the voltage converter. The destination of the signal notifying the abnormality is, for example, a higher-level controller. The voltage conversion device disclosed in this specification monitors whether the output voltage of the voltage converter exceeds the overvoltage determination threshold while the load is disconnected from the voltage converter. In other words, the voltage conversion device disclosed in this specification can check whether the voltage converter is overloaded without being affected by the load.

[0006] Details and further improvements of the technology disclosed in this specification are described in the following "Forms for Carrying Out the Invention". [Brief description of the drawings]

[0007] [Figure 1] 1 is a block diagram of a power system of an electric vehicle including a voltage conversion device according to an embodiment of the present invention; [Diagram 2] 13 is a flowchart of an excessive output state check process executed by the controller. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] A voltage conversion device 10 according to an embodiment will be described with reference to the drawings. The voltage conversion device 10 is mounted on an electric vehicle 100. Fig. 1 shows a block diagram of the power system of the electric vehicle 100. The dashed arrow lines in Fig. 1 represent signal lines.

[0009] The electric vehicle 100 includes a high-voltage battery 101, a bidirectional converter 102, an inverter 103, a motor 104 for driving, and a host controller 106. The output voltage of the high-voltage battery 101 is 100 volts or more, for example, 400 volts. The output terminal of the high-voltage battery 101 is connected to a DC terminal of the inverter 103 via the bidirectional converter 102. A motor 104 is connected to an AC terminal of the inverter 103. The output shaft of the motor 104 is coupled to an axle (not shown).

[0010] The bidirectional converter 102 converts the output voltage of the high-voltage battery 101 into a voltage suitable for driving the motor 104, and supplies the voltage-converted power to the inverter 103. The inverter 103 converts the supplied DC power into AC power suitable for driving the motor 104. The motor 104 may generate power using the inertial energy of the vehicle. The power obtained by the generation of power by the motor 104 (regenerative power) is converted into DC power by the inverter 103, and is further converted into a voltage suitable for charging the high-voltage battery 101 by the bidirectional converter 102. The high-voltage battery 101 is charged with the regenerative power.

[0011] A host controller 106 receives information from the vehicle's main switch 107 (ignition switch), an accelerator opening sensor 108, a speed sensor 105 that measures the vehicle speed (the number of rotations of the motor 104), and the like, and controls the bidirectional converter 102 and the inverter 103.

[0012] The electric vehicle 100 also includes a voltage conversion device 10. The voltage conversion device 10 is connected between a high-voltage battery 101 and a low-voltage battery 111. The voltage conversion device 10 includes a voltage converter 12, an overvoltage detector 18, and a load cutoff relay 15. The output voltage of the low-voltage battery 111 is less than 100 volts, for example 12 volts. An input terminal 12a of the voltage converter 12 is connected to the high-voltage battery 101, and an output terminal 12b of the voltage converter 12 is connected to the low-voltage battery 111. The negative output terminal of the voltage converter 12 is connected to ground G. The entire body of the electric vehicle 100 serves as ground G of the low-voltage system.

[0013] An output end 12b of the voltage converter 12 is connected to a connection terminal 13 via a load cutoff relay 15, and an accessory power line 110 is connected to the connection terminal 13. The accessory power line 110 is laid out throughout the vehicle, and in addition to a low-voltage battery 111, an audio system 112a, a room lamp 112b, and the like are connected to the accessory power line 110. Devices that operate on the voltage of the low-voltage battery 111, such as the audio system 112a and the room lamp 112b, are collectively referred to as accessories 112. In addition to the audio system 112a and the room lamp 112b, various accessories are connected to the accessory power line 110.

[0014] The voltage converter 12 reduces the output voltage of the high-voltage battery 101 to the voltage of the low-voltage battery 111. The voltage converter 12 is controlled by a controller 14. When the remaining power of the low-voltage battery 111 becomes low (when the output voltage of the low-voltage battery 111 becomes low), the controller 14 drives the voltage converter 12 to charge the low-voltage battery 111 with the power of the high-voltage battery 101. Alternatively, the controller 14 controls the voltage converter 12 so that a predetermined amount of power is supplied from the voltage converter 12 to the low-voltage battery 111 and the auxiliary equipment 112 while the vehicle is running.

[0015] When the controller 14 commands the voltage converter 12 to have a target voltage, the voltage converter 12 operates so that the voltage at the output terminal 12b coincides with the target voltage. The voltage converter 12 has a feedback loop for detecting the voltage at the output terminal 12b. Two voltage dividing resistors 16a and 16b are connected in series between the output terminal 12b and the ground G. A midpoint 17 of the series connection of the two voltage dividing resistors 16a and 16b is connected to a feedback terminal 12c of the voltage converter 12. The voltage at the output terminal 12b divided by the two voltage dividing resistors 16a and 16b is applied to the feedback terminal 12c. The voltage converter 12 detects the voltage at the output terminal 12b from the voltage at the feedback terminal 12c, and controls itself so that the voltage at the output terminal 12b coincides with the target voltage.

[0016] An overvoltage detector 18 is connected to the output terminal 12b to determine whether or not the voltage at the output terminal 12b exceeds a predetermined overvoltage determination threshold. The overvoltage detector 18 typically includes a voltage sensor. When the voltage at the output terminal 12b exceeds the overvoltage determination threshold, the overvoltage detector 18 notifies the controller 14 of the fact.

[0017] Voltage conversion device 10 has a function of monitoring whether voltage converter 12 is in an excessive output state (excessive output state check function). Fig. 2 shows a flowchart of the excessive output state check process. The excessive output state check process is started, for example, when main switch 107 is turned on (or when main switch 107 is turned off). The fact that main switch 107 has been turned on (or turned off) is notified to controller 14 from upper controller 106. Note that these are merely examples, and the excessive output state check process may be started by other events.

[0018] When the excessive output state check process is started, the controller 14 first stops the voltage converter 12 (S12). If the voltage converter 12 is stopped when processing step S12, the controller 14 does nothing in step S12. Next, the controller 14 opens the load cut-off relay 15 (S13). When the load cut-off relay 15 is opened, the output terminal 12b of the voltage converter 12 is cut off from loads such as the low-voltage battery 111 and the auxiliary equipment 112. The output terminal 12b of the voltage converter 12 is in an open state with nothing connected. The load cut-off relay 15 is normally closed, and is opened during the excessive output state check process. If the voltage converter 12 is not in an excessive output state, the load cut-off relay 15 is closed in step S19. This point will be described later.

[0019] Next, the controller 14 starts a timer (step S14). Next, the controller 14 commands a target voltage to the voltage converter 12, and drives the voltage converter 12. The target voltage is set to a value lower than an overvoltage determination threshold value, which will be described later. Typically, the target voltage is set to a voltage sufficient for charging the low-voltage battery 111. The overvoltage determination threshold value is set to a value higher than the target voltage, for example, "target voltage + 10 volts."

[0020] The timer is a variable defined in the program of the excessive output state check process, and is a variable for measuring the elapsed time from when a target voltage is commanded and voltage converter 12 starts to be driven.

[0021] During a predetermined waiting time after driving the voltage converter 12 by issuing a target voltage command, the controller 14 monitors whether or not the voltage at the output terminal 12b exceeds the overvoltage determination threshold (steps S16, S17: NO). As described above, the overvoltage detector 18 is connected to the output terminal 12b, and when the overvoltage detector 18 detects that the voltage at the output terminal 12b has exceeded the overvoltage determination threshold, a signal is sent from the overvoltage detector 18 to the controller 14.

[0022] If the voltage at output terminal 12b does not exceed the overvoltage determination threshold before the waiting time has elapsed, controller 14 stops voltage converter 12, closes load cutoff relay 15, and ends the process (steps S17: YES, S18, S19). If the voltage at output terminal 12b does not exceed the overvoltage determination threshold before the waiting time has elapsed, it is determined that voltage converter 12 is not in an excessive output state. In this case, although not shown in FIG. 2, controller 14 sends a signal indicating that there is no abnormality to upper controller 106. Having received the signal indicating that there is no abnormality, upper controller 106 proceeds to the next process (for example, a process of making the vehicle ready to run).

[0023] If the voltage at output terminal 12b exceeds the overvoltage determination threshold before the waiting time has elapsed (step S16: YES), controller 14 outputs a signal (abnormality notification signal) indicating that an abnormality has occurred in voltage converter 12 (step S21). Finally, controller 14 stops voltage converter 12 and ends the process.

[0024] The abnormality notification signal is sent to upper controller 106. Upon receiving the abnormality notification signal, upper controller 106 notifies the user that an abnormality has occurred in voltage converter 12 (voltage conversion device 10), for example by turning on a warning light on an instrument panel.

[0025] For example, if voltage dividing resistor 16a breaks, the voltage at feedback terminal 12c of voltage converter 12 becomes equal to the voltage of ground G. Voltage converter 12 is no longer able to feed back the voltage at output end 12b, and operates to increase the voltage at open output end 12b as much as possible, resulting in an over-output state. When the voltage at output end 12b exceeds the over-voltage determination threshold, over-voltage detector 18 sends a signal to controller 14. Having received the signal, controller 14 learns that voltage converter 12 is in an over-output state, stops voltage converter 12, and sends an abnormality notification signal to host controller 106.

[0026] In this way, when the conditions for starting the overload check process are met, the controller 14 of the voltage conversion device 10 opens the load cutoff relay 15 and cuts off the output terminal 12b of the voltage converter 12 from the load (the low-voltage battery 111 and the auxiliary equipment 112). This process places the output terminal 12b in an open state. The voltage conversion device 10 operates the voltage converter 12 after placing the output terminal 12b in an open state, and monitors whether or not the voltage at the output terminal 12b exceeds the overvoltage determination threshold. By keeping the output terminal 12b in an open state, the output terminal 12b is prevented from being affected by the load during the overload check.

[0027] If output terminal 12b is connected to a load and the current consumption of the connected load is large, even if voltage converter 12 is in an excessive output state, power may flow from output terminal 12b to the load, and the voltage of output terminal 12b may not exceed the overvoltage determination threshold. In that case, controller 14 may not be able to detect the excessive output state of voltage converter 12. Voltage conversion device 10 sets output terminal 12b of voltage converter 12 to an open state and then monitors the voltage of output terminal 12b. By such processing, voltage conversion device 10 can reliably detect the excessive output state of voltage converter 12.

[0028] Points to note regarding the technology described in the embodiment will be described. The voltage conversion device 10 of the embodiment is mounted on an electric vehicle 100. The voltage conversion device 10 may be used in devices other than electric vehicles. The voltage converter 12 may be a circuit that can step up or step down the voltage applied to the input terminal 12a and output it from the output terminal 12b. The voltage converter 12 may be an insulated converter using a transformer, or a non-insulated converter using a switching element.

[0029] When voltage converter 12 is in an excessive output state, controller 14 may output a command signal to the instrument panel to turn on a warning light as a signal indicating an abnormality in voltage converter 12 .

[0030] Although specific examples of the present invention have been described above in detail, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and variations of the specific examples exemplified above. The technical elements described in this specification or drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or drawings can achieve multiple objectives simultaneously, and achieving one of these objectives is itself technically useful. [Explanation of symbols]

[0031] 10: Voltage conversion device 12: Voltage converter 12a: Input terminal 12b: Output terminal 12c: Feedback terminal 13: Connection terminal 14: Controller 15: Load cut-off relay 16a, 16b: Voltage dividing resistor 17: Midpoint 18: Overvoltage detector 100: Electric vehicle 101: High-voltage battery 102: Bidirectional converter 103: Inverter 104: Motor 105: Speed ​​sensor 106: Upper controller 107: Main switch 108: Accelerator opening sensor 110: Accessory power line 111: Low-voltage battery 112a: Audio (auxiliary equipment) 112b: Room lamp (auxiliary equipment)

Claims

[Claim 1] a voltage converter having a power source connected to an input end; a connection terminal to which a load that receives power from the voltage converter is connected; a relay connected between the output terminal of the voltage converter and the connection terminal; a controller for controlling the voltage converter and the relay; Equipped with the controller opens the relay, and outputs a signal indicating an abnormality in the voltage converter when the output end voltage exceeds a predetermined overvoltage determination threshold higher than the target voltage in a state in which the controller issues a command to the voltage converter to set the output end voltage of the voltage converter to a target voltage. Voltage conversion device.

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