Power supply device

Abstract

A power supply device (100) comprises: a DC-DC converter (10); a control IC (20) to which an output voltage of the DC-DC converter (10) is fed back and controls the DC-DC converter (10) so that the output voltage reaches a target voltage; and a transmission circuit (30) that transmits to the control IC (20) a signal for causing the DC-DC converter (10) to operate or stop, the signal being input from an ECU (500). When a signal for stopping the DC-DC converter (10) is input, the transmission circuit (30) causes the control IC (20) to stop the DC-DC converter (10) or stops the control IC (20) before the voltage fed back to the control IC (20) decreases.

Description

power supply

[0001] The present disclosure relates to a power supply device including a DC-DC converter.

[0002] Patent Document 1 discloses a technique related to a DC-DC converter.

[0003] JP 2016-63745 A

[0004] In a typical DC-DC converter, the output voltage is fed back to the control unit so that the output voltage reaches a target voltage, and the control unit controls the DC-DC converter. When a signal to shut down the DC-DC converter is input from an external device to the power supply, the power supply to the control unit is cut off, shutting down the control unit and the DC-DC converter. The control unit receives power from a power source connected to the output terminal of the DC-DC converter, and the power supply to the control unit can be cut off by cutting off the path connecting the output terminal and the control unit. Because a bypass capacitor or other device is connected to the power terminal of the control unit, it takes time for the voltage at the power terminal of the control unit to drop even when the path is cut off, and the voltage fed back to the control unit drops before the control unit is shut down. This causes the control unit to mistakenly recognize that the output voltage has dropped significantly below the target voltage and control the DC-DC converter to increase the output voltage, resulting in a sudden increase in output voltage.

[0005] Therefore, the present disclosure provides a power supply device that can suppress a sudden rise in output voltage when a DC-DC converter is stopped.

[0006] The power supply device of the present disclosure comprises a DC-DC converter, a control unit that controls the DC-DC converter by feeding back the output voltage of the DC-DC converter so that the output voltage becomes a target voltage, and a transmission circuit that transmits a signal to the control unit that operates or stops the DC-DC converter, which is input from an external device of the power supply device, and when a signal to stop the DC-DC converter is input, the transmission circuit causes the control unit to stop the DC-DC converter or stops the control unit before the voltage fed back to the control unit drops.

[0007] These comprehensive or specific aspects may be realized as a system, a method, an integrated circuit, a computer program, or a computer-readable recording medium such as a CD-ROM, or may be realized as any combination of a system, a method, an integrated circuit, a computer program, and a recording medium.

[0008] According to the power supply device according to an aspect of the present disclosure, it is possible to suppress a sudden increase in output voltage when the DC-DC converter is stopped.

[0009] Fig. 1 is a configuration diagram showing an application example of a power supply device according to an embodiment; Fig. 2 is a configuration diagram showing an example of a power supply device according to an embodiment; Fig. 3 is a circuit configuration diagram showing an example of a power supply device according to a comparative example; Fig. 4 is a circuit configuration diagram showing a first example of a power supply device according to an embodiment; Fig. 5 is a circuit configuration diagram showing a second example of a power supply device according to an embodiment; Fig. 6 is a circuit configuration diagram showing a third example of a power supply device according to an embodiment.

[0010] Hereinafter, the embodiments will be specifically described with reference to the drawings.

[0011] The embodiments described below are all comprehensive or specific examples, and the numerical values, shapes, materials, components, arrangement and connection of the components, steps, and order of steps shown in the following embodiments are merely examples and are not intended to limit the present disclosure.

[0012] (Embodiment) A power supply device according to an embodiment will be described below.

[0013] FIG. 1 is a configuration diagram showing an application example of a power supply device 100 according to an embodiment.

[0014] The power supply device 100 is a device equipped with a DC-DC converter that steps up or steps down an input voltage to a predetermined voltage and outputs the resulting voltage. In the following, an example will be described in which the DC-DC converter equipped in the power supply device 100 is an isolated DC-DC converter, but the DC-DC converter does not have to be an isolated DC-DC converter.

[0015] For example, the power supply device 100 is mounted on the electric motorcycle 1 and steps down a high voltage of several hundred volts from a high-voltage battery 200, such as a lithium-ion battery, mounted on the electric motorcycle 1, and outputs a voltage of several volts to several tens of volts. The voltage of the high-voltage battery 200 is also supplied to an inverter 400 and a motor mounted on the electric motorcycle 1. The electric motorcycle 1 requires the power supply device 100 equipped with a DC-DC converter to supply power from the high-voltage battery 200 to low-voltage devices such as a low-voltage battery 300, such as a lead-acid battery, an ECU (Electronic Control Unit) 500, and motorcycle electrical equipment 600 mounted on the electric motorcycle 1. The power supply device 100 may also be mounted on transportation equipment other than the electric motorcycle 1, such as an automobile.

[0016] The ECU 500 is an example of a device external to the power supply device 100, and a signal for operating or stopping the DCDC converter is input from the ECU 500 to the power supply device 100. Note that the device external to the power supply device 100 is not limited to the ECU 500, but is not particularly limited as long as it is a device mounted on a transportation device (for example, the electric motorcycle 1) on which the power supply device 100 is mounted.

[0017] Next, the function of the power supply device 100 will be described with reference to FIG.

[0018] 2 is a configuration diagram showing an example of a power supply device 100 according to an embodiment of the present invention. In addition to the power supply device 100, an ECU 500 is also shown in FIG.

[0019] The power supply device 100 includes a DC-DC converter 10 , a control IC 20 , and a transmission circuit 30 .

[0020] The control IC 20 controls the DC-DC converter 10 by feeding back the output voltage of the DC-DC converter 10 so that the output voltage becomes a target voltage. The control IC 20 is an example of a control unit. The DC-DC converter 10 includes a switch element for stepping up or stepping down the input voltage to a predetermined voltage, and the control IC 20 controls the DC-DC converter 10 by controlling the switch element.

[0021] The transmission circuit 30 transmits a signal input from the ECU 500 to operate or stop the DCDC converter 10 to the control IC 20. Specifically, when a signal to stop the DCDC converter 10 is input, the transmission circuit 30 causes the control IC 20 to stop the DCDC converter 10 before the voltage fed back to the control IC 20 drops. Alternatively, when a signal to stop the DCDC converter 10 is input, the transmission circuit 30 causes the control IC 20 to stop the DCDC converter 10 before the voltage fed back to the control IC 20 drops. Specific examples of the transmission circuit 30 will be described later.

[0022] By providing such a transmission circuit 30, the DC-DC converter 10 can be stopped before the voltage fed back to the control IC 20 drops, thereby preventing the output voltage from rising suddenly when the DC-DC converter 10 is stopped.

[0023] Here, a power supply device that does not include such a transmission circuit 30 will be described with reference to FIG.

[0024] 3 is a circuit diagram showing an example of a power supply device 100a according to a comparative example, which also shows an ECU 500 in addition to the power supply device 100a.

[0025] The power supply device 100a includes a DC-DC converter 10, a control IC 20, an internal power supply circuit 40, resistors R1, R2, R3, R4, and R5, capacitors C1 and C2, and switch elements Q1 and Q3.

[0026] The DC-DC converter 10 is, for example, an isolated DC-DC converter and includes an isolation transformer and an LC circuit consisting of a power inductor and a smoothing capacitor. The DC-DC converter 10 smoothes a pulse voltage output from a secondary winding of the isolation transformer using the LC circuit and outputs the smoothed voltage to output terminals t1 and t2.

[0027] A low-voltage battery 300, an ECU 500, and motorcycle electrical equipment 600 are connected to output terminals t1 and t2, and a low voltage is applied between the output terminals t1 and t2. For example, a voltage of several volts to several tens of volts is output from output terminal t1 (Vout+) to output terminal t2 (Vout-). An external terminal t3 is a terminal connected to the ECU 500. A signal (ON signal) for operating the DCDC converter 10 or a signal (OFF signal) for stopping the DCDC converter 10 is input from the ECU 500 to the external terminal t3. For example, the signal for operating the DCDC converter 10 is an H-level signal, and the signal for stopping the DCDC converter 10 is an L-level signal.

[0028] The control IC 20 is realized by, for example, a microcomputer. The control IC 20 has a power supply terminal (Vcc), a feedback terminal (FB), an enable terminal (EN), and an output terminal (OUT). The power supply terminal of the control IC 20 is a terminal for supplying power to the control IC 20. The feedback terminal of the control IC 20 is a terminal to which the output voltage of the DCDC converter 10 (the voltage at the output terminal t1) is fed back. The enable terminal of the control IC 20 is a terminal for causing the control IC 20 to stop the DCDC converter 10. The output terminal of the control IC 20 is a terminal for outputting a PWM (Pulse Width Modulation) control signal for controlling the DCDC converter 10, and is connected to a switch element of the DCDC converter 10.

[0029] The switch element Q1 is controlled by an ON / OFF signal from the ECU 500. For example, the switch element Q1 is an NPN bipolar transistor. The base of the switch element Q1 is connected to the external terminal t3, the collector of the switch element Q1 is connected to the resistor R2, and the emitter of the switch element Q1 is connected to ground.

[0030] A resistor R3 and a capacitor C1 are connected in parallel between a node between the base of the switching element Q1 and the external terminal t3 and ground, and resistors R1 and R2 are connected in series between the collector of the switching element Q1 and the output terminal t1.

[0031] The switch element Q3 is connected to the external terminal t3 via the switch element Q1 and is controlled by an ON / OFF signal from the ECU 500. For example, the switch element Q3 is a P-channel metal oxide semiconductor field effect transistor (MOSFET). The gate of the switch element Q3 is connected to a node between the resistors R1 and R2, the drain of the switch element Q3 is connected to the output terminal t1, and the source of the switch element Q3 is connected to the input terminal of the internal power supply circuit 40 and the resistor R4.

[0032] Resistors R4 and R5 are connected in series between the source of switch element Q3 and ground. The output terminal of internal power supply circuit 40 is connected to the power supply terminal of control IC 20. Capacitor C2 is connected between ground and a node between the power supply terminal of control IC 20 and the output terminal of internal power supply circuit 40. Capacitor C2 is, for example, a bypass capacitor. The feedback terminal of control IC 20 is connected to a node between resistors R4 and R5.

[0033] The internal power supply circuit 40 generates an operating voltage required for the operation of the control IC 20 from the output voltage of the DC-DC converter 10. The voltage generated by the internal power supply circuit 40 is applied to the power supply terminal of the control IC 20, thereby enabling the control IC 20 to operate.

[0034] When a signal (H-level signal) for operating the DCDC converter 10 is input from the ECU 500 to the external terminal t3, the switch element Q1 becomes conductive, and the voltage applied to the gate of the switch element Q3 decreases, so that the switch element Q3 also becomes conductive. As a result, the voltage output from the DCDC converter 10 is supplied to the internal power supply circuit 40, and the voltage generated by the internal power supply circuit 40 is applied to the power supply terminal of the control IC 20. As a result, the control IC 20 operates, and the DCDC converter 10 operates.

[0035] When a signal (L-level signal) to stop the DC-DC converter 10 is input from the ECU 500 to the external terminal t3, the switch element Q1 becomes non-conductive, and the voltage applied to the gate of the switch element Q3 increases, causing the switch element Q3 to also become non-conductive. The non-conductive state of the switch element Q3 cuts off the power supply to the control IC 20. At this time, because a capacitor C2, such as a bypass capacitor, is connected to the power supply terminal of the control IC 20, it takes time for the voltage at the power supply terminal of the control IC 20 to decrease even when the switch element Q3 becomes non-conductive. The control IC 20 controls the DC-DC converter 10 while feeding back the output voltage to the control IC 20 so that the output voltage becomes the target voltage. However, before the control IC 20 is stopped, the voltage fed back to the control IC 20 decreases. Therefore, the control IC 20 erroneously recognizes that the output voltage has dropped significantly below the target voltage and controls the DC-DC converter 10 to increase the output voltage, resulting in a sudden increase in the output voltage.

[0036] Thus, the power supply device 100a not provided with the transmission circuit 30 has a problem in that the output voltage rises suddenly when the DC-DC converter 10 is stopped. On the other hand, the power supply device 100 according to the embodiment is provided with the transmission circuit 30, and therefore the DC-DC converter 10 can be stopped before the voltage fed back to the control IC 20 drops, and therefore the output voltage can be prevented from rising suddenly when the DC-DC converter 10 is stopped.

[0037] First to third examples of the power supply device 100 will be described below.

[0038] First, a first example of the power supply device 100 will be described with reference to FIG.

[0039] Fig. 4 is a circuit configuration diagram showing a first example of a power supply device 100 according to an embodiment. Fig. 4 shows a power supply device 101 as an example of the power supply device 100 according to the embodiment. Also, a transmission circuit 31 is shown as an example of the transmission circuit 30. In addition to the power supply device 101, Fig. 4 also shows an ECU 500.

[0040] The power supply device 101 includes a DC-DC converter 10, a control IC 20, a transmission circuit 31, an internal power supply circuit 40, resistors R4 and R5, and a capacitor C2. The DC-DC converter 10, the control IC 20, the internal power supply circuit 40, the resistors R4 and R5, and the capacitor C2 are the same as those in the power supply device 100a according to the comparative example, and therefore description thereof will be omitted.

[0041] The transmission circuit 31 includes resistors R1, R2, R3, R6, R7, R8, R9, R10, and R11, a capacitor C1, and switch elements Q1, Q2, Q3, and Q4. The resistors R1, R2, and R3, the capacitor C1, and the switch elements Q1 and Q3 are essentially the same as those in the power supply device 100a of the comparative example, and therefore will not be described here. The power supply device 100a of the comparative example differs from the power supply device 100a of the comparative example in that the base of the switch element Q1 is connected to the external terminal t3 via a resistor R7. The switch element Q3 is an example of a second switch provided in the feedback path of the output voltage from the DC-DC converter 10 to the control IC 20 (specifically, the path connecting the output terminal t1 and the feedback terminal of the control IC 20). The capacitor C1 is an example of a capacitor provided in the path connecting the external terminal t3 and the switch element Q3 (specifically, the path connecting the external terminal t3 and the switch element Q1). The resistor R7 is an example of a second resistor provided in the path connecting the external terminal t3 and the switch element Q3 (specifically, the path connecting the external terminal t3 and the switch element Q1).

[0042] The switch element Q2 is controlled by an ON / OFF signal from the ECU 500. The switch element Q2 is an example of a first switch provided in a path connecting an external terminal t3 connected to the ECU 500 and an enable terminal of the control IC 20 for stopping the DC-DC converter 10. For example, the switch element Q2 is an NPN bipolar transistor. The base of the switch element Q2 is connected to the external terminal t3 via a resistor R8, the collector of the switch element Q2 is connected to a power supply (e.g., the output terminal of the internal power supply circuit 40) via a resistor R10, and the emitter of the switch element Q2 is connected to ground. The collector of the switch element Q2 is also connected to the base of the switch element Q4. A resistor R6 is connected between a node between the base of the switch element Q2 and the resistor R8 and ground. The resistor R8 is an example of a first resistor provided in a path connecting the external terminal t3 connected to the ECU 500 and an enable terminal of the control IC 20 for stopping the DC-DC converter 10.

[0043] The switch element Q4 is connected to the external terminal t3 via the switch element Q2 and a resistor R8, and is controlled by an ON / OFF signal from the ECU 500. For example, the switch element Q4 is an NPN bipolar transistor. The base of the switch element Q4 is connected to the collector of the switch element Q2, the collector of the switch element Q4 is connected to an enable terminal of the control IC 20, and the emitter of the switch element Q4 is connected to ground. A resistor R11 is connected between ground and a node between the base of the switch element Q4 and the collector of the switch element Q2. The enable terminal of the control IC 20 is connected to a power supply (for example, the output terminal of the internal power supply circuit 40) via a resistor R9.

[0044] When a signal (H-level signal) for operating the DC-DC converter 10 is input from the ECU 500 to the external terminal t3, the voltage generated by the internal power supply circuit 40 is applied to the power supply terminal of the control IC 20, causing the control IC 20 to operate, and the DC-DC converter 10 to operate, similar to the power supply device 100a according to the comparative example. Furthermore, when a signal for operating the DC-DC converter 10 is input from the ECU 500 to the external terminal t3, the switch element Q2 becomes conductive, reducing the voltage applied to the base of the switch element Q4, causing the switch element Q4 to become non-conductive. This causes the power supply voltage (e.g., the output voltage of the internal power supply circuit 40) to be applied to the enable terminal of the power supply IC 20. For example, when a L-level signal is input to the enable terminal of the power supply IC 20, the power supply IC 20 stops the DC-DC converter 10. When a signal to operate the DC-DC converter 10 is input from the ECU 500 to the external terminal t3, an H-level signal is input to the enable terminal of the power supply IC 20, so that the power supply IC 20 does not stop the DC-DC converter 10.

[0045] When a signal (L-level signal) to shut down the DC-DC converter 10 is input from the ECU 500 to the external terminal t3, the base of the switch element Q1 is connected to the capacitor C1 and the resistor R7. Therefore, it takes time for the voltage applied to the base of the switch element Q1 to drop, depending on the time constant of the circuit consisting of the capacitor C1 and the resistor R7. On the other hand, no capacitor is connected to the base of the switch element Q2. Therefore, the switch element Q2 becomes non-conductive before the switch element Q1, and the voltage applied to the base of the switch element Q4 rises, causing the switch element Q4 to become conductive. This connects the enable terminal of the power supply IC 20 to ground. In other words, because an L-level signal is input to the enable terminal of the power supply IC 20, the power supply IC 20 shuts down the DC-DC converter 10.

[0046] Thereafter, the voltage applied to the base of switch element Q1 drops, causing switch element Q1 to enter a non-conductive state, and the voltage applied to the gate of switch element Q3 rises, causing switch element Q3 to also enter a non-conductive state and cutting off the power supply to control IC 20. At this time, because capacitor C2 is connected to the power supply terminal of control IC 20, it takes time for the voltage at the power supply terminal of control IC 20 to drop even when switch element Q3 enters a non-conductive state, and the voltage fed back to control IC 20 drops before control IC 20 is shut down. However, because a signal (L-level signal) that shuts down the DCDC converter 10 is input to the enable terminal of control IC 20, control IC 20 does not control DCDC converter 10 to increase the output voltage.

[0047] As described above, since capacitor C1 is provided between external terminal t3 and switch element Q3 (specifically, switch element Q1 connected to switch element Q3) and no capacitor is provided between external terminal t3 and switch element Q2, when a signal to stop the DCDC converter 10 is input, transmission circuit 31 can operate switch element Q2 before switch element Q1 and therefore switch element Q3. Therefore, before switch element Q3 operates and the voltage fed back to control IC 20 drops, switch element Q2 operates and a signal to stop the DCDC converter 10 can be input to the enable terminal of control IC 20. Therefore, control IC 20 can stop the DCDC converter 10 before the voltage fed back to control IC 20 drops, thereby preventing the output voltage from rising sharply when the DCDC converter 10 is stopped.

[0048] Next, a second example of the power supply device 100 will be described with reference to FIG.

[0049] Fig. 5 is a circuit diagram showing a second example of the power supply device 100 according to the embodiment. Fig. 5 shows a power supply device 102 as an example of the power supply device 100 according to the embodiment. In addition to the power supply device 102, Fig. 5 also shows an ECU 500.

[0050] Power supply device 102 differs from power supply device 101 in that it includes transmission circuit 32 instead of transmission circuit 31, and further includes an abnormality detection circuit 50. Transmission circuit 32 differs from transmission circuit 31 in that it does not include resistors R9, R10, and R11 or switch element Q4. Since other points are the same as those in power supply device 101, the following description will focus on the differences.

[0051] The abnormality detection circuit 50 is a circuit that detects abnormalities in the DC-DC converter 10. For example, it detects abnormalities in the input voltage or output voltage of the DC-DC converter 10, or abnormal temperatures. The abnormality detection circuit 50 is provided on a path connecting the external terminal t3 and an enable terminal of the control IC 20 for stopping the DC-DC converter 10. For example, the abnormality detection circuit 50 is provided between the collector of the switch element Q2 and the enable terminal of the control IC 20. Specifically, the input terminal of the abnormality detection circuit 50 is connected to the collector of the switch element Q2, and the output terminal of the abnormality detection circuit 50 is connected to the enable terminal of the control IC 20. Although not shown, the input terminal of the abnormality detection circuit 50 is pulled up via a pull-up resistor.

[0052] For example, when the abnormality detection circuit 50 detects an abnormality, it outputs an L-level signal to the enable terminal of the control IC 20. This allows the control IC 20 to stop the DCDC converter 10. Furthermore, for example, when an H-level signal is input to the input terminal of the abnormality detection circuit 50, the abnormality detection circuit 50 also outputs an L-level signal to the enable terminal of the control IC 20. When a signal (L-level signal) to stop the DCDC converter 10 is input from the ECU 500 to the external terminal t3, the switch element Q2 becomes non-conductive and an H-level signal is input to the input terminal of the abnormality detection circuit 50, allowing the control IC 20 to stop the DCDC converter 10.

[0053] In this way, the transmission circuit 32 transmits a signal to stop the DCDC converter 10 to the control IC 20 via the abnormality detection circuit 50. For example, the terminal to which the signal from the abnormality detection circuit 50 is input as the enable terminal of the control IC 20 can also be used as a terminal to which a signal to stop the DCDC converter 10 is input from the ECU 500. This makes it possible to save terminals of the control IC 20, such as a microcomputer.

[0054] In addition, in the power supply device 102, as in the power supply device 101, the switch element Q2 can be operated before the switch element Q3, and the control IC 20 can stop the DCDC converter 10 before the voltage fed back to the control IC 20 drops, thereby preventing the output voltage from rising suddenly when the DCDC converter 10 is stopped.

[0055] Next, a third example of the power supply device 100 will be described with reference to FIG.

[0056] Fig. 6 is a circuit diagram showing a third example of the power supply device 100 according to the embodiment. Fig. 6 shows a power supply device 103 as an example of the power supply device 100 according to the embodiment. In addition to the power supply device 103, Fig. 6 also shows an ECU 500.

[0057] Power supply device 103 differs from power supply device 101 in that it includes transmission circuit 33 instead of transmission circuit 31. Transmission circuit 33 differs from transmission circuit 31 in that it includes resistors R12 and R13 and switch elements Q5 and Q6 instead of resistors R6, R7, R8, R9, R10, and R11 and switch element Q4. Another difference is that resistor R4 is not connected to the source of switch element Q3. Since the remaining points are the same as those in power supply device 101, the following description will focus on the differences.

[0058] For example, the switch element Q6 is an NPN bipolar transistor. The base of the switch element Q6 is connected to the output terminal of the internal power supply circuit 40, the collector of the switch element Q6 is connected to the resistor R13, and the emitter of the switch element Q6 is connected to ground.

[0059] The switch element Q5 is provided in a feedback path of the output voltage from the DC-DC converter 10 to the control IC 20 (specifically, a path connecting the output terminal t1 and the feedback terminal of the control IC 20) and is an example of a third switch that operates in response to an operating voltage generated by the internal power supply circuit 40 (i.e., a voltage applied to the power supply terminal of the control IC 20). Specifically, the switch element Q5 operates when the switch element Q6 operates in response to the operating voltage generated by the internal power supply circuit 40. For example, the switch element Q5 is a P-channel MOSFET. The drain of the switch element Q5 is connected to the output terminal t1. Resistors R12 and R13 are connected in series between the drain of the switch element Q5 and the collector of the switch element Q6. The gate of the switch element Q5 is connected to a node between the resistors R12 and R13. The source of the switch element Q5 is connected to the resistor R4.

[0060] When a signal (H-level signal) for operating the DCDC converter 10 is input from the ECU 500 to the external terminal t3, the voltage generated by the internal power supply circuit 40 is applied to the power supply terminal of the control IC 20, similar to the power supply device 101, causing the control IC 20 to operate and the DCDC converter 10 to operate. Furthermore, when the voltage generated by the internal power supply circuit 40 is applied to the switch element Q6, the switch element Q6 becomes conductive, and the voltage applied to the gate of the switch element Q5 decreases, causing the switch element Q5 to become conductive. This causes the output voltage of the DCDC converter 10 to be fed back to the feedback terminal of the control IC 20. Thus, when a signal for operating the DCDC converter 10 is input from the ECU 500 to the external terminal t3, the DCDC converter 10 operates.

[0061] When a signal (L-level signal) to shut down the DC-DC converter 10 is input from the ECU 500 to the external terminal t3, the switch elements Q1 and Q3 enter a non-conductive state, cutting off the power supply to the control IC 20, just as in the power supply device 101. At this time, because the capacitor C2 is connected to the power supply terminal of the control IC 20, it takes time for the voltage at the power supply terminal of the control IC 20 to fall below a predetermined voltage, even when the switch element Q3 enters a non-conductive state. The predetermined voltage is a voltage at which the control IC 20 cannot operate and is higher than the drive voltage of the switch element Q6. Because the switch element Q6 remains conductive until the voltage at the power supply terminal of the control IC 20 falls below the predetermined voltage, the switch element Q5 also remains conductive, preventing a decrease in the voltage fed back to the control IC 20. When the voltage at the power supply terminal of the control IC 20 subsequently falls below the predetermined voltage, the control IC 20 shuts down, and the DC-DC converter 10 shuts down accordingly. Thereafter, the switch element Q6 becomes non-conductive, and the switch element Q5 also becomes non-conductive, but since the control IC 20 has already stopped, even if the voltage fed back to the control IC 20 decreases, the control IC 20 cannot control the DCDC converter 10 to increase the output voltage.

[0062] In this way, when a signal to stop the DC-DC converter 10 is input to the external terminal t3, the switch element Q5 cuts off the feedback path when the operating voltage of the control IC 20 falls below a predetermined voltage. As a result, the operating voltage required for the operation of the control IC 20 becomes small enough that the control IC 20 itself stops, and then the feedback path is cut off. Therefore, the control IC 20 can be stopped before the voltage fed back to the control IC 20 drops. Therefore, a sudden rise in output voltage can be suppressed when the DC-DC converter 10 is stopped.

[0063] (Other Embodiments) As described above, the embodiments have been described as examples of the technology according to the present disclosure. However, the technology according to the present disclosure is not limited to these, and can be applied to embodiments in which modifications, substitutions, additions, omissions, etc. are made as appropriate. For example, the following modifications are also included in one embodiment of the present disclosure.

[0064] In the above embodiment, an example has been described in which the transmission circuit 31 of the power supply device 101 includes elements other than the switch element Q2 and the resistor R8 in the path connecting the external terminal t3 and the enable terminal of the control IC 20. However, it is sufficient for the transmission circuit 31 to include at least the switch element Q2 and the resistor R8 in the path, and the other elements are not particularly limited to those shown in FIG.

[0065] In the above embodiment, an example has been described in which the transmission circuit 31 of the power supply device 101 includes elements other than the resistor R7 and the capacitor C1 in the path connecting the external terminal t3 and the switch element Q3. However, it is sufficient for the transmission circuit 31 to include at least the resistor R7 and the capacitor C1 in the path, and the other elements are not particularly limited to those shown in FIG. 4.

[0066] In the above embodiment, an example has been described in which the switch element Q6 or the like is used in the transmission circuit 33 of the power supply device 103 so that the switch element Q5 can cut off the feedback path, but the elements used by the switch element Q5 to cut off the feedback path are not limited to those shown in FIG. 6.

[0067] In the above embodiment, each component included in power supply device 100 may be configured with dedicated hardware, or may be realized by executing a software program suitable for each component. Each component may also be realized by a program execution unit such as a CPU or processor reading and executing a software program recorded on a recording medium such as a hard disk or semiconductor memory.

[0068] Some or all of the functions of the power supply device 100 according to the above-described embodiment are typically realized as an LSI, which is an integrated circuit. These may be individually integrated into single chips, or some or all of them may be integrated into a single chip. Furthermore, the integrated circuit is not limited to an LSI, and may be realized using a dedicated circuit or a general-purpose processor. It is also possible to use an FPGA (Field Programmable Gate Array), which can be programmed after LSI manufacturing, or a reconfigurable processor, which can reconfigure the connections and settings of circuit cells within an LSI.

[0069] Furthermore, if an integrated circuit technology that can replace LSI emerges due to advances in semiconductor technology or other derivative technologies, it is natural that each component included in power supply device 100 may be integrated using that technology.

[0070] In addition, this disclosure also includes forms obtained by making various modifications to the embodiments that a person skilled in the art would think of, and forms realized by arbitrarily combining the components and functions in each embodiment within the scope of the present disclosure.

[0071] (Additional Notes) The above description of the embodiments discloses the following techniques.

[0072] (Technology 1) A power supply device comprising: a DC-DC converter; a control unit that controls the DC-DC converter by feeding back the output voltage of the DC-DC converter so that the output voltage becomes a target voltage; and a transmission circuit that transmits a signal to the control unit that operates or stops the DC-DC converter, the signal being input from a device external to the power supply device; when a signal to stop the DC-DC converter is input, the transmission circuit causes the control unit to stop the DC-DC converter or stops the control unit before the voltage fed back to the control unit drops.

[0073] In a typical DC-DC converter, the output voltage is fed back to the control unit so that the output voltage reaches a target voltage, and the control unit controls the DC-DC converter. When a signal to shut down the DC-DC converter is input from an external device to the power supply unit, the power supply to the control unit is cut off, shutting down the control unit and the DC-DC converter. The control unit receives power from a power source connected to the output terminal of the DC-DC converter, and the power supply to the control unit can be cut off by cutting off the path connecting the output terminal and the control unit. Because a capacitor, such as a bypass capacitor, is connected to the power terminal of the control unit, it takes time for the voltage at the power terminal of the control unit to drop even when the path is cut off, and the voltage fed back to the control unit drops before the control unit is shut down. This causes the control unit to mistakenly recognize that the output voltage has dropped significantly below the target voltage and control the DC-DC converter to increase the output voltage, resulting in a sudden increase in output voltage.

[0074] Therefore, in the present disclosure, a transmission circuit is provided that, when a signal to stop the DCDC converter is input, causes the control unit to stop the DCDC converter or stops the control unit itself before the voltage fed back to the control unit drops. By providing such a transmission circuit, the DCDC converter can be stopped before the voltage fed back to the control unit drops, thereby preventing a sudden increase in output voltage when the DCDC converter is stopped.

[0075] (Technology 2) The power supply device described in Technology 1, wherein the transmission circuit includes a first switch and a first resistor provided in a path connecting an external terminal connected to the external device and a terminal of the control unit for stopping the DCDC converter, a second switch provided in a feedback path of the output voltage from the DCDC converter to the control unit, and a second resistor and a capacitor provided in a path connecting the external terminal and the second switch, and when a signal to stop the DCDC converter is input, the first switch is operated before the second switch.

[0076] According to this, a capacitor is provided between the external terminal and the second switch, but no capacitor is provided between the external terminal and the first switch, so that when a signal to stop the DCDC converter is input, the transmission circuit can operate the first switch before the second switch. Therefore, before the second switch operates and the voltage fed back to the control unit drops, the first switch operates and the signal to stop the DCDC converter can be input to the control unit's terminal for stopping the DCDC converter. Therefore, the control unit can stop the DCDC converter before the voltage fed back to the control unit drops, so that a sudden rise in output voltage can be suppressed when the DCDC converter is stopped.

[0077] (Technology 3) The power supply device according to Technology 2 further includes an abnormality detection circuit provided in a path connecting the external terminal and a terminal of the control unit for stopping the DC-DC converter, and the transmission circuit transmits a signal for stopping the DC-DC converter to the control unit via the abnormality detection circuit.

[0078] For example, the terminal for inputting a signal from the abnormality detection circuit as a terminal for stopping the DCDC converter can also be used as a terminal for inputting a signal for stopping the DCDC converter from an external device, thereby saving terminals in the control unit such as a microcomputer.

[0079] (Technology 4) The power supply device described in Technology 1, wherein the transmission circuit comprises an internal power supply circuit that generates an operating voltage required for operation of the control unit from the output voltage, and a third switch that is provided in a feedback path of the output voltage from the DC-DC converter to the control unit and operates according to the operating voltage, and the third switch cuts off the feedback path when the operating voltage falls below a predetermined voltage when a signal to stop the DC-DC converter is input.

[0080] This allows the control unit to be stopped before the voltage fed back to the control unit drops, thereby preventing a sudden rise in output voltage when the DC-DC converter is stopped.

[0081] (Technology 5) The power supply device according to any one of technologies 1 to 4, wherein the external device is an ECU.

[0082] This makes it possible to prevent the output voltage from rising suddenly when a signal to stop the DCDC converter is output from the ECU.

[0083] (Technology 6) The power supply device according to any one of technologies 1 to 5, wherein the power supply device is mounted on an electric motorcycle.

[0084] In this way, the power supply device of the present disclosure may be mounted on an electric motorcycle.

[0085] The present disclosure can be applied to power supply devices for electric motorcycles, etc.

[0086] 10 DC-DC converter 20 Control IC 30, 31, 32, 33 Transmission circuit 40 Internal power supply circuit 50 Abnormality detection circuit 100, 100a, 101, 102, 103 Power supply device 200 High-voltage battery 300 Low-voltage battery 400 Inverter 500 ECU 600 Motorcycle electrical equipment C1, C2 Capacitor Q1, Q2, Q3, Q4, Q5, Q6 Switch element R1, R2, R3, R4, R5, R6, R7, R8, R9, R10, R11, R12, R13 Resistor t1, t2 Output terminal t3 External terminal

Claims

1. A power supply comprising: a DC-DC converter; a control unit that controls the DC-DC converter by feeding back the output voltage of the DC-DC converter so that the output voltage becomes a target voltage; and a transmission circuit that transmits a signal to the control unit that operates or stops the DC-DC converter, the signal being input from a device external to the power supply; wherein, when a signal to stop the DC-DC converter is input, the transmission circuit causes the control unit to stop the DC-DC converter or stops the control unit before the voltage fed back to the control unit drops.

2. The power supply device of claim 1, wherein the transmission circuit comprises: a first switch and a first resistor provided in a path connecting an external terminal connected to the external device and a terminal of the control unit for stopping the DCDC converter; a second switch provided in a feedback path of the output voltage from the DCDC converter to the control unit; and a second resistor and a capacitor provided in a path connecting the external terminal and the second switch; and wherein when a signal for stopping the DCDC converter is input, the first switch is operated before the second switch.

3. The power supply device according to claim 2, further comprising an abnormality detection circuit provided in a path connecting the external terminal and a terminal of the control unit for stopping the DCDC converter, and the transmission circuit transmits a signal for stopping the DCDC converter to the control unit via the abnormality detection circuit.

4. The power supply device of claim 1, wherein the transmission circuit comprises: an internal power supply circuit that generates an operating voltage required for operation of the control unit from the output voltage; and a third switch that is provided in a feedback path of the output voltage from the DC-DC converter to the control unit and operates in accordance with the operating voltage, and wherein the third switch cuts off the feedback path when the operating voltage falls below a predetermined voltage when a signal to stop the DC-DC converter is input.

5. The power supply device according to any one of claims 1 to 4, wherein the external device is an ECU.

6. The power supply device according to any one of claims 1 to 5, wherein the power supply device is mounted on an electric motorcycle.

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