JP2009254187A - Double system power source - Google Patents

Abstract

To realize a dual power supply device capable of always diagnosing whether or not a power supply switching circuit is normal and identifying a failure part when a failure has occurred and warning a user.
Power from a main battery is supplied from a circuit breaker through a main power supply line to an inverter and motor load. The electric power of the sub battery 6 is also supplied to the load 17 through the switches 7 to 10 and the sub power supply line 11. The operation of the circuit breaker 3 and the switches 7 to 10 is controlled by the microcomputer 16, and during the normal operation, the circuit breaker 3 is turned on and the switches 7 to 10 are turned off, and from the sub power supply line 11 to the inverter and the motor load 17. Power supply is cut off. The microcomputer 16 is connected to the gates of the switches 7 to 10 through control lines 18 to 20 and 26, the switches 7 and 8 are monitored by the transistor 15, and the switches 9 and 10 are monitored by the transistor 14.
[Selection] Figure 1

Description

  The present invention relates to a dual power supply apparatus.

  In recent years, devices that have been conventionally hydraulically or mechanically operated, such as automobile brakes and transmission shift mechanisms, have been electrified. This improves the safety and mobility of the vehicle due to the excellent controllability of the electrical equipment.

  However, these electrical devices have a power source of electrical energy, and if the power source that is the power source fails, or if the load connected in parallel to the power source fails, the power source of the system fails. The function of the electrical equipment has also been lost.

  In order to avoid such a failure of the electrical device function due to such a failure, Patent Document 1 describes a device that uses a dual power source and switches the power source appropriately to maintain the power source.

JP 2000-31444 A

  However, in the above prior art, it is not determined whether or not the power supply switching circuit can operate normally, and power is supplied from the power supply system in which a failure has occurred to another power supply system among the dual power supply systems. There is no guarantee that the switching circuit will operate reliably.

  For this reason, when it becomes necessary to switch the power supply, there is a possibility that the power supply switching circuit does not operate and the backup function of the power supply cannot be achieved.

  An object of the present invention is to always perform diagnosis of whether or not a power switching circuit can operate normally in a dual power supply apparatus, and if a failure has occurred, identify the failure part and warn the user. It is to realize a dual power supply device capable of achieving the above.

  In order to achieve the above object, the present invention is configured as follows.

  The dual system power supply device of the present invention is formed by connecting in series so that the sources and drains of four P-MOS semiconductor switches are alternately connected, and connected between the sub power supply and the load. Switching circuit, control means for controlling opening / closing operation of the circuit breaker and on / off operation of each semiconductor switch of the switching circuit, and monitoring means for monitoring the source voltage of the semiconductor switch of the switching circuit and outputting a monitor signal to the control means The control means closes the circuit breaker, performs the on / off operation of each semiconductor element during the power supply period from the main power supply to the load, and diagnoses the failure of each semiconductor switch based on the monitor signal from the monitor means I do.

  In a dual system power supply unit, it is always possible to diagnose whether or not the power supply switching circuit can operate normally, and if a fault has occurred, the faulty part can be identified and the user can be alerted A power supply device can be realized.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  1 is an overall configuration diagram of a dual power supply apparatus according to an embodiment of the present invention. In FIG. 1, 1 is a main battery charging device, and 2 is a main battery. 5 is a sub-battery charging device, and 6 is a sub-battery.

  The electric power of the main battery 1 is supplied from the circuit breaker 3 to the inverter and the motor load 17 through the main power supply line 4. Further, the power of the sub-battery 6 is also the switch (SW1) 7, the switch (SW2) 8, the switch (SW3) 9, the switch (SW4) 10 (first semiconductor switch, second semiconductor switch, third semiconductor switch). , The fourth semiconductor switch) and the sub power supply line 11 to be supplied to the inverter and the motor load 17.

  The operations of the circuit breaker 3, the switch (SW1) 7, the switch (SW2) 8, the switch (SW3) 9, and the switch (SW4) 10 are controlled by the microcomputer 16, and during the normal operation, the circuit breaker 3 is on. The switches (SW1) to (SW4) 10 are turned off, and power supply from the sub power supply line 11 to the inverter and the motor load 17 is cut off. The microcomputer 16 is connected to the gate of the switch (SW1) 7 through the control line 20.

  Similarly, the microcomputer 16 is connected to the gates of the switch (SW2) 8, the switch (SW3) 9, and the switch (SW4) 10 through control lines 19, 18, and 26. On / off of the circuit breaker 3 is controlled from the microcomputer 16 via the I / F 12.

  The switch (SW1) 7, the switch (SW2) 8, the switch (SW3) 9, and the switch (SW4) 10 are field effect transistors having a P-type MOS structure. A semiconductor switch that can be energized between the drain and the drain.

  The I / F 13 is an interface for monitoring the voltage of the main power supply line 4, is connected between the main battery 2 and the circuit breaker 3, and outputs an analog signal to the microcomputer 16.

  Now, an operation when a ground fault or disconnection failure occurs in the main power supply line 4 will be described with reference to FIG.

  When a ground fault or disconnection failure occurs in the main power supply line 4, the voltage of the main power supply line 4 drops (time t0 in FIG. 2).

  The microcomputer 16 monitors the voltage of the main power supply line 4 with a built-in A / D converter, and shuts off the circuit breaker 3 when the voltage is below a threshold value Vth for a threshold time Tth (time t1). ).

  The threshold voltage Vth at the time of the ground fault is set within a range not lower than the minimum operating voltage of the microcomputer 16 and the I / F 12.

  The microcomputer 16 can be supplied with power from the main power supply line 4 via the diode 21, capacitor 22, regulator 23, and line 24, and from the sub power supply line 11 via the regulator 23 and line 24. Also, power is supplied. The electric power supplied to the microcomputer 16 is stored in the capacitor 22 so that the operation of the microcomputer 16 can be maintained even if the main power supply line 4 fails.

  Further, when a ground fault or the like occurs in the main power supply line 4, there is a possibility that the electric charge stored in the capacitor 22 may be discharged to the ground fault location, but this is prevented by the diode 21.

  After shutting off the circuit breaker 3 at time t1, the switch (SW1) 7, the switch (SW2) 8, the switch (SW3) 9, and the switch (SW4) 10 are turned on to supply power to the load 17 from the sub power supply line 11 To do.

  When switching the power supply from the sub power supply 6 to the load 17, the switch (SW1) 7, the switch (SW2) 8, the switch (SW3) 9, and the switch (SW4) 10 must be switched after the circuit breaker 3 is completely cut off. It is necessary to turn it on.

  If the switch (SW1) 7, the switch (SW2) 8, the switch (SW3) 9, and the switch (SW4) 10 are turned on before the circuit breaker 3 is completely blocked, the electric energy stored in the sub-battery 6 is It is because it will flow to the short-circuit fault location via the circuit breaker 3 and unnecessarily consume electric energy.

  Further, when the switches (SW1) 7 to (SW4) 10 are turned on, it is preferable to turn them on almost simultaneously. When it is impossible to turn on at the same time, the switch (SW2) 8 is set earlier than the switch (SW1) 7 and the switch (SW4) 10 is turned on earlier than the switch (SW3) 9 (time points t2, t3). It is important to.

  For example, an inconvenience when the switch (SW3) 9 is turned on earlier than the switch (SW4) 10 when the switch (SW1) 7 and the switch (SW2) 8 are on will be described.

  In this case, the electrical energy stored in the sub-battery 6 is switched to the switch (SW4) 10 until the switch (SW4) 10 is turned on via the switch (SW1) 7, the switch (SW2) 8, and the switch (SW3) 9. Is supplied to the inverter and the motor load 17 via the parasitic diode.

  A parasitic diode is a diode that is generated in a parasitic manner around a channel in manufacturing a MOS semiconductor. The forward voltage by the diode is normally about 0.5V to 1V, and if a load current flows through this parasitic diode, a huge loss occurs in the switch (SW4) 10, which causes overheating and further damage. There is a possibility.

  Further, inconvenience when the switch (SW1) 7 is turned on earlier than the switch (SW2) 8 while the switch (SW3) 9 and the switch (SW4) 10 are on will be described.

  In this case, the electrical energy stored in the sub-battery 6 is supplied to the switch (SW2) 8 until the switch (SW2) 8 is turned on via the switch (SW3) 9, the switch (SW4) 10, and the switch (SW1) 7. Is supplied to the inverter and the motor load 17 via the parasitic diode. In this case, too much loss is generated in the switch (SW2) 8, which may cause overheating and even damage.

  As described above, the failure of the main power supply line 4 is detected, and the power from the sub power supply line 11 is supplied to the inverter and the motor load 17 for backup.

  Next, a failure diagnosis method for the backup power supply line 11 during normal operation of the main power supply line 4 will be described with reference to FIGS. 3, 4, and 5.

  As shown in FIGS. 3 and 4, during normal operation of the main power supply line 4, the switch (SW 1) to the switch (SW 4) 10 are controlled to be switched while the circuit breaker 3 is on.

(Failure diagnosis of switch (SW1) 7)
First, failure diagnosis of the switch (SW1) 7 will be described. The switches (SW1) 7 to (SW4) 10 are connected from the sub battery 6 toward the regulator 23 in the order of source, drain, drain, source, source, drain, drain, and source. The base of the transistor 15 is connected to the drain of the switch (SW1) 7 and the source of the switch (SW2) 8, and the emitter of the transistor 15 is grounded. The collector of the transistor 15 is connected to the output line 24 of the regulator 23 via a resistor and to the microcomputer 16.

  For this reason, the voltage of the backup power supply 6 is always applied to the drain of the switch (SW1) 7, and if the OFF operation of the switch (SW1) 7 is normal, no voltage is generated on the source side of the switch (SW1) 7. . If no voltage is generated on the source side of the switch (SW1) 7, the transistor 15 for monitoring the switch (SW1) 7 and the switch (SW2) 8 is not turned on, and the SW1, 2 monitor output (the collector output of the transistor 15) ) Is maintained at the H level (time point t1 in FIGS. 3, 4 and 5).

  In this case, the voltage of the main power supply line 4 can be applied to the sub power supply line 11 via the inverter and the motor load 17, but is blocked by the parasitic diodes of the switch (SW 2) 8 and the switch (SW 4) 10. Here, even if one of the switch (SW2) 8 and the switch (SW4) 10 is short-circuited, the voltage is blocked by the action of the parasitic diode of the switch that is not short-circuited. Is possible.

  Further, the ON operation of the switch (SW1) 7 can be confirmed by performing the switches (SW2) 8 to (SW4) in the OFF state and monitoring the voltage of the source of the switch (SW1) 7. That is, when the switch (SW1) 7 is turned on, if a voltage is generated at the source of the switch (SW1) 7, the transistor 15 is turned on, and the monitor outputs (SW1, 2MONI) become L level (FIG. 3, FIG. 4 and time point t2) in FIG.

  When the switch (SW1) 7 has a short circuit fault, a potential is generated on the source side of the switch (SW1) 7 even when the switch (SW1) 7 is turned off. When voltage is generated on the source side of the switch (SW1) 7, the transistor 15 for monitoring the switch (SW1) 7 and the switch (SW2) 8 is turned on, and the monitor output becomes L level (FIG. 3). 4 and FIG. 5, time point t4).

  In this case, when the charging voltage of the sub battery 6 is higher than the charging voltage of the main battery 2, the current from the sub battery 6 flows into the parasitic diode of the switch (SW 2) 8 via the switch (SW 1) 7 that is short-circuited. However, the resistor connected between the connection point of the switch (SW2) 8 and the switch (SW3) 9 (the point where four semiconductor switches connected in series with each other are divided into two) and the main power supply line 4 By 25, the flowing current is limited. For this reason, the switch (SW2) 8 is not overheated.

  On the contrary, when the charging voltage of the main battery 2 is higher than the charging voltage of the sub battery 6, the flowing current is blocked by the parasitic diode of the switch (SW 2) 8.

  When the switch (SW1) 7 has an open failure, no potential is generated on the source side of the switch (SW1) 7 even when the switch (SW1) 7 is turned on. If no voltage is generated on the source side of the switch (SW1) 7, the transistor 15 is not turned on, and the monitor output is in an H level output state (time point t5 in FIGS. 3, 4 and 5).

  The voltage may be monitored by monitoring the voltage as an analog signal, or by forming a transistor switch circuit that turns on at a preset threshold voltage and logically judging the output of the transistor monitor circuit.

(Failure diagnosis of switch (SW2) 8)
Next, a failure diagnosis method for the switch (SW2) 8 will be described.

  When the switch (SW1) 7, the switch (SW3) 9, and the switch (SW4) 10 are off, a bias voltage is applied from the main battery 2 through the resistor 25 to the drain of the switch (SW2) 8. The power supply destination of the resistor 25 may be supplied from the sub-battery 6 as shown in FIG.

  If the off operation of the switch (SW2) 8 functions normally, no voltage is generated on the source side of the switch (SW2) 8. If no voltage is generated on the source side of the switch (SW2) 8, the transistor 15 is not turned on, and the monitor outputs SW1 and MONI of the switches 7 and 8 are at the H level (as shown in FIGS. 3, 4 and 5). t1). In this way, the switch (SW2) 8 off diagnosis is performed.

  Next, the switch (SW2) 8 is turned on while the switch (SW1) 7, the switch (SW3) 9, and the switch (SW4) 10 are off. When the switch (SW2) 8 is turned on, the line voltage of the main power supply 2 applied via the resistor 25 appears at the source of the switch (SW2) 8. With this voltage, the transistor 15 is turned on, and the monitor outputs SW1 and MONI of the switches 7 and 8 become L level (time point t3 in FIGS. 3, 4 and 5).

  At this time, when the charging voltage of the main battery 2 is higher than the charging voltage of the sub battery 6, the current from the main battery 2 flows into the parasitic diode of the switch (SW 1) 7 via the switch (SW 2) 8. However, since the flowing-in current is limited by the resistor 25, the switch (SW1) 7 is not overheated.

  On the contrary, when the charging voltage of the sub battery 6 is higher than the charging voltage of the main battery 2, the flowing current is blocked by the parasitic diode of the switch (SW 1) 7. In this way, the on-operation diagnosis of the switch (SW2) 8 is performed.

  When the switch (SW2) 8 has a short circuit fault, a potential is generated on the source side of the switch (SW2) 8 even when the switch (SW2) 8 is turned off. When a voltage is generated on the source side of the switch (SW2) 8, the transistor 15 is turned on, and the monitor outputs of the switches 7 and 8 become L level (time point t4 in FIGS. 3, 4 and 5).

  At this time, when the charging voltage of the main battery 2 is higher than the charging voltage of the sub-battery 6, the current from the main battery 2 flows into the parasitic diode of the switch (SW 1) 7 via the short-circuited switch (SW 2) 8. However, since the flow-in current is limited by the resistor 25, the switch (SW1) 7 is not overheated. On the contrary, when the charging voltage of the main battery 2 is higher than the charging voltage of the sub battery 6, the flowing current is blocked by the parasitic diode of the switch (SW 1) 7.

  When the switch (SW2) 8 has an open failure, no potential is generated on the source side of the switch (SW2) 8 even when the switch (SW2) 8 is turned on. If no voltage is generated on the source side of the switch (SW2) 8, the transistor 15 is not turned on, and the monitor outputs of the switches 7 and 8 are at the H level (time point t6 in FIGS. 3, 4 and 5).

  The voltage may be monitored as an analog signal, or a transistor switch circuit that is turned on with a preset threshold voltage may be formed, and the output of the transistor monitor circuit may be logically determined.

(Failure diagnosis of switch (SW3) 9)
Next, a failure diagnosis method for the switch (SW3) 9 will be described.

  When the switch (SW1) 7, the switch (SW2) 8, and the switch (SW4) 10 are off, a bias voltage is applied to the drain of the switch (SW3) 9 from the main power supply line 4 via the resistor 25. Yes. As shown in FIG. 6, the power supply destination of the resistor 25 may be supplied from the sub battery 6 in addition to the main power supply line 4.

  If the off operation of the switch (SW3) 9 is functioning normally, no voltage is generated on the source side of the switch (SW3) 9. If no voltage is generated on the source side of the switch (SW3) 9, the transistor 14 for monitoring the switch (SW3) 9 and the switch (SW4) 10 is not turned on, and the monitor output becomes the H level (FIG. 3). 4 and FIG. 5 at time t1). The base of the transistor 14 is connected to the connection point between the switch (SW3) 9 and the switch (SW4) 10, and the emitter is grounded. The collector of the transistor 14 is connected to the output line 24 of the regulator 23 through a resistor and to the microcomputer 16.

  In this way, the switch (SW3) 9 is turned off.

  Next, the switch (SW3) 9 is turned on while the switch (SW1) 7, the switch (SW2) 8, and the switch (SW4) 10 are off. When the switch (SW3) 9 is turned on, the line voltage of the main power supply 2 applied via the resistor 25 appears at the source of the switch (SW3) 9. With this voltage, the transistor 14 is turned on, and the monitor outputs SW3 and 4MONI of the switches 9 and 10 become L level (time point t3 in FIGS. 3, 4 and 5).

  At this time, when the charging voltage of the main battery 2 is higher than the charging voltage of the sub battery 6, the current from the main battery 2 flows into the parasitic diode of the switch (SW 4) 10 via the switch (SW 3) 9. However, since the flowing-in current is limited by the resistor 25, the switch (SW4) 10 is not overheated.

  On the contrary, when the charging voltage of the sub battery 6 is higher than the charging voltage of the main battery 2, the flowing current is blocked by the parasitic diode of the switch (SW 1) 7. In this way, the on-operation diagnosis of the switch (SW3) 9 is executed.

  When the switch (SW3) 9 has a short circuit fault, even when the switch (SW3) 9 is turned off, a potential is generated on the source side of the switch (SW3) 9. When a voltage is generated on the source side of the switch (SW3) 9, the transistor 14 for monitoring the switches 9 and 10 is turned on, and the monitor outputs SW3 and 4MONI are at the L level (FIGS. 3, 4 and Time t9 in FIG.

  When the switch (SW3) 9 has caused an open failure, no potential is generated on the source side of the switch (SW3) 9 even when the switch (SW3) 9 is turned on. If no voltage is generated on the source side of the switch (SW3) 9, the transistor 14 for monitoring the switches 9 and 10 is not turned on, and the monitor outputs SW3 and 4MONI are at the H level (FIGS. 3, 4 and FIG. 5 time t7).

  The voltage may be monitored as an analog signal, or a transistor switch circuit that is turned on with a preset threshold voltage may be formed to logically determine the output of the transistor monitor circuit. .

(Failure diagnosis of switch (SW4) 10)
Next, failure diagnosis of the switch (SW4) 10 will be described. The voltage of the main battery 2 is constantly applied to the drain of the switch (SW4) 10 via the circuit breaker 3. If the off operation of the switch (SW4) 10 is normal, no voltage is generated on the source side of the switch (SW4) 10. If no voltage is generated on the source side of the switch (SW4) 10, the transistor 14 for monitoring the switches 9 and 10 is not turned on, and the monitor outputs SW3 and 4MONI are at the H level (FIGS. 3, 4 and Time t1 in FIG.

  In this case, the voltage of the backup power supply line 11 can be applied to the main power supply line 4 via the inverter and the motor load 17, but is blocked by the parasitic diodes of the switch (SW 1) 7 and the switch (SW 3) 9. Here, even if one of the switch (SW1) 7 and the switch (SW3) 9 is short-circuited, the voltage can be blocked by the action of the other parasitic diode.

  The switch (SW4) 10 is turned on by turning on the switch (SW4) 10 with the switch (SW1) 7, the switch (SW2) 8, and the switch (SW3) 9 turned off, and the source of the switch (SW4) 10. This can be confirmed by monitoring the voltage.

  That is, when a voltage is generated at the source of the switch (SW4) 10 when the switch (SW4) 10 is turned on, the transistor 14 for monitoring the switches 9 and 10 is turned on, and the monitor outputs SW3 and 4MONI are at the L level. (Time point t2 in FIGS. 3, 4 and 5).

  When the switch (SW4) 10 has a short circuit failure, even when the switch (SW4) 10 is turned off, a potential is generated on the source side of the switch (SW4) 10. When a voltage is generated on the source side of the switch (SW4) 10, the monitor 14 of the switches 9 and 10 is turned on, and the monitor outputs SW3 and 4MONI are at the L level (FIGS. 3, 4 and FIG. 5 time t9).

  When the switch (SW4) 10 has an open failure, no potential is generated on the source side of the switch (SW4) 10 even when the switch (SW4) 10 is turned on. If no voltage is generated on the source side of the switch (SW4) 10, the transistor 14 for monitoring the switches 9 and 10 is not turned on, and the monitor outputs SW3 and 4MONI are at the H level (FIGS. 3, 4 and FIG. 5 time t8).

  As described above, according to the present invention, it is possible to constantly diagnose whether or not the power supply switching circuit can be normally operated, and when a failure occurs, it is possible to identify the failure part and warn the user. A simple dual power supply can be realized.

  Furthermore, according to the present invention, even when the sub power source 6 is in operation, the back electromotive force due to the regenerative action of the motor load can be absorbed by the sub power source 6 itself.

  Further, while the main power supply 2 is energized, it is possible to perform short circuit and open failure diagnosis of the sub power supply switching circuit (switches 7 to 10).

  In the diagnosis operation, diagnosis can be performed regardless of the magnitude of the main power supply voltage, the sub power supply voltage, and the load side voltage.

  The voltage may be monitored as an analog signal, or a transistor switch circuit that is turned on with a preset threshold voltage may be formed to logically determine the output of the transistor monitor circuit. .

  Further, the diagnosis is configured so that the main power supply 2 is always diagnosed while the main power supply 2 is operating normally. However, the diagnosis can be performed only at the initial stage or at the end of the apparatus startup.

  Further, when the microcomputer 16 determines that a failure has occurred as a result of the diagnosis of the switches 7 to 10, the microcomputer 16 issues an alarm and displays the failure portion and the failure content as shown in FIG. 5 on the display means. Is possible.

  The transistors 14 and 15 are used as monitoring means for monitoring the source voltage of the semiconductor switches 7 to 10. However, the source voltage between the semiconductor switch 7 and the semiconductor switch 8 and the source between the semiconductor switch 9 and the semiconductor switch 10 are used. A threshold determination circuit that compares a voltage with a threshold and outputs a signal indicating the comparison result to the control means may be used.

  Furthermore, the present invention can be applied not only to a power supply device for a vehicle, but also to other devices as long as the device is equipped with a battery and operates with electric power from the battery. For example, the present invention can be applied to ships, robots, machine tools, video cameras, and the like.

1 is an overall configuration diagram of a dual power supply apparatus according to an embodiment of the present invention. 6 is a switching circuit on / off switching operation timing chart when a fault such as a ground fault occurs in an embodiment of the present invention. It is a constant diagnosis timing chart of the switching circuit in one embodiment of the present invention. It is a figure which shows the relationship between the diagnostic content and time in one Embodiment of this invention. It is a figure which shows the diagnostic logic in one Embodiment of this invention. It is a figure which shows the modification of one Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Main battery charging device, 2 ... Main battery, 3 ... Circuit breaker, 4 ... Main power supply line, 5 ... Sub battery charging device, 6 ... Sub battery, 7- DESCRIPTION OF SYMBOLS 10 ... Semiconductor switch (switching circuit), 11 ... Backup power supply line, 12 ... Circuit breaker drive interface, 13 ... Main power supply line voltage monitor interface, 14, 15 ... Transistor (monitor) Circuit), 16 ... microcomputer, 17 ... inverter and motor, 18-20, 26 ... control line, 21 ... diode, 22 ... capacitor, 23 ... power regulator, 25 ... ·resistance

Claims (6)

The main power supply,
A circuit breaker connected between the main power source and the load;
Sub power supply,
A switching circuit formed by connecting the P-MOS semiconductor switches connected in series so that the sources and drains of the semiconductor switches are alternately connected, and connected between the sub power source and the load;
Control means for controlling the opening / closing operation of the circuit breaker and the on / off operation of each semiconductor switch of the switching circuit;
Monitoring means for monitoring a source voltage of the semiconductor switch of the switching circuit and outputting a monitor signal to the control means;
The control means closes the circuit breaker, performs an on / off operation of each semiconductor element during a power supply period from a main power source to a load, and based on a monitor signal from the monitor means, A dual power supply device characterized by performing a switch failure diagnosis.   2. The dual power supply apparatus according to claim 1, wherein a bias voltage is applied to the drains of the four semiconductor switches by a bias voltage supply means, and the control means causes each of the semiconductor elements to perform an on / off operation, and thereby the monitoring means. A dual-system power supply device characterized in that a failure diagnosis of each semiconductor switch is performed based on the source voltage of each semiconductor switch monitored by the above.   3. The dual power supply apparatus according to claim 2, wherein the bias voltage is a resistance connected between the main power supply or the sub power supply and the point where the four semiconductor switches connected in series are divided into two. A dual-system power supply device characterized by that.   3. The dual power supply apparatus according to claim 2, wherein the semiconductor switches connected in series are connected in series in the order of a first semiconductor switch, a second semiconductor switch, a third semiconductor switch, and a fourth semiconductor switch, and the monitoring means. Is switch means that is turned on and off by the voltage levels of the source voltage between the first semiconductor switch and the second semiconductor switch and the source voltage between the third semiconductor switch and the fourth semiconductor switch, The dual power supply apparatus according to claim 1, wherein the control means diagnoses a failure of each of the semiconductor switches based on an on / off signal of the switch means.   3. The dual power supply apparatus according to claim 2, wherein the semiconductor switches connected in series are connected in series in the order of a first semiconductor switch, a second semiconductor switch, a third semiconductor switch, and a fourth semiconductor switch, and the monitoring means. Is a signal indicating a result of comparing the source voltage between the first and second semiconductor switches and the source voltage between the third and fourth semiconductor switches with a threshold value. Is output to the control means.   2. The dual power supply apparatus according to claim 1, wherein the dual power supply apparatus is mounted on a vehicle.

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