JP2011234567A - Power circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power circuit capable of preventing, even in case that MOSFET is impossible to turn on by a drive circuit failure or the like, the case from having an adverse effect upon the MOSFET.SOLUTION: A control circuit 211, when a detection circuit 210 detects some failure in a drive circuit 209, controls a drive circuit 208 to flow overcurrent through a fuse 203 and hence to cut off electric conduction between a battery 100 and an inductor 205. When a detection circuit 308 detects some failure in a drive circuit 307, the control circuit 211 controls a drive circuit 306 to flow overcurrent through a fuse 301 and hence to cut off electric conduction between the battery 100 and an inductor 303.

Description

  The present invention relates to a power supply circuit that maintains supply of a necessary voltage to an electrical component even when the voltage of a battery temporarily decreases.

  In recent years, idle stop vehicles have been put into practical use for the purpose of reducing fuel consumption and reducing exhaust gas. The idle stop vehicle is a vehicle that automatically stops the engine when it detects a stop of the vehicle, such as waiting for a signal, and then automatically restarts the engine when it detects a start operation of the vehicle.

  In such a vehicle, when the engine is restarted, a large current flows through the starter motor for starting the engine, so that the battery voltage temporarily decreases. Along with this, the voltage supplied to the electrical components in the vehicle also temporarily decreases. For this reason, depending on the electrical component, the supplied voltage may be out of the operating range and may not temporarily operate normally. For example, a driver's unintended operation such as resetting may be performed in car navigation or audio, or sound skipping may occur in audio. Therefore, the idle stop vehicle is provided with an auxiliary power supply circuit so that the supply of a necessary voltage to the electrical component can be maintained even when the voltage of the battery temporarily decreases.

  As an auxiliary power supply circuit provided in an idle stop vehicle, for example, there is a circuit in which a booster circuit is provided and an output voltage is controlled by controlling a switching element in the booster circuit (see, for example, Patent Document 1). In this circuit, normally, current is passed through the inductor and rectifier diode in the booster circuit without switching operation by the switching element, and when the engine is restarted, the voltage boosted by switching operation by the switching element is applied to the electric load. To supply.

  However, in such an auxiliary power supply circuit, since a current always flows through a rectifying diode provided in the booster circuit in a normal state, a decrease in efficiency due to loss in the diode and heat dissipation of the diode are problems. Become.

  Therefore, there is also an auxiliary power supply circuit in which a MOSFET (rectifying MOSFET) is provided instead of the diode and the MOSFET is turned on to prevent the efficiency from decreasing. This circuit operates as a circuit because current flows through the body diode (parasitic diode) of the MOSFET even if the drive circuit that drives the MOSFET fails or cannot be turned on. Will do.

JP 2005-237149 A

  However, when the MOSFET cannot be turned on as described above, a current always flows through the body diode of the MOSFET, and the temperature of the MOSFET rises due to heat dissipation of the body diode. In this case, since the current flowing through the body diode cannot be stopped by the control circuit in the booster circuit, the temperature rise of the MOSFET cannot be suppressed and self-protection cannot be performed. Therefore, the temperature rise may adversely affect the MOSFET.

  In view of the above circumstances, the present invention provides a power supply circuit that can prevent a MOSFET from being adversely affected even when the MOSFET cannot be turned on due to a drive circuit failure or the like. Objective.

  A power supply circuit according to a first aspect of the present invention includes a DC power supply, a first switching element, a first inductor provided between the DC power supply and the first switching element, and the first A second switching element provided between the inductor and the electric load; a first diode connected in parallel to the second switching element; and the DC power source and the first inductor due to an overcurrent flowing therein A first shut-off means for shutting off the energization, a first drive means for driving the first switching element, a second drive means for driving the second switching element, and the second First detection means for detecting an abnormality of the drive means, a third switching element, a second inductor provided between the DC power supply and the third switching element, and the second inductor And a second diode connected in parallel to the fourth switching element, and the DC power supply and the second inductor when an overcurrent flows. , A second driving unit for driving the third switching element, a fourth driving unit for driving the fourth switching element, and the fourth driving unit for driving the fourth switching element, A second detecting means for detecting an abnormality of the driving means, and controlling the first to fourth driving means to drive the first to fourth switching elements, thereby driving the voltage of the DC power supply, or the And a control means for outputting a voltage obtained by boosting the voltage of the DC power supply. When the first detection means detects an abnormality of the second drive means, the control means Driving means An overcurrent is controlled to flow to the first shut-off means to cut off the energization between the DC power supply and the first inductor, and the second detection means causes an abnormality of the fourth drive means. If it is detected, the third drive means is controlled to pass an overcurrent through the second shut-off means, thereby shutting off the energization between the DC power supply and the second inductor. With such a configuration, even if the second or fourth drive circuit fails or the second or fourth switching element cannot be turned on, the direct current power source, the first or second inductor, Since the energization is interrupted, the second or fourth switching element can be prevented from being adversely affected.

  The power supply circuit according to a second aspect of the present invention is the power supply circuit according to the first aspect, wherein the control means turns off the second switching element when turning on the first switching element, The first and second driving means are controlled so that the second switching element is turned on when the switching element is turned off, and the fourth switching element is turned off when the third switching element is turned on. And controlling the third and fourth driving means to turn on the fourth switching element when the third switching element is turned off, thereby boosting the voltage of the DC power supply, and When an abnormality of the second drive means is detected by one detection means, the first drive means is controlled to cause the overcurrent to flow through the first cutoff means. After cutting off energization between the power source and the first inductor, when the third switching element is turned on, the fourth switching element is turned off, and when the third switching element is turned off, the third switching element is turned off. By controlling the third and fourth driving means so as to turn on the fourth switching element, the voltage of the DC power supply is boosted, and the abnormality of the fourth driving means is detected by the second detecting means. If detected, after the current between the DC power source and the second inductor is interrupted by controlling the third driving means to flow an overcurrent to the second interrupting means, The second switching element is turned off when the first switching element is turned on, and the second switching element is turned on when the first switching element is turned off. By controlling the first and second driving means boosts the voltage of the DC power supply. As a result, when an abnormality of the second driving means is detected, the voltage of the DC power source is boosted by controlling the third and fourth driving means, and an abnormality of the fourth driving means is detected. The voltage of the DC power supply can be boosted by controlling the first and second driving means.

  The power supply circuit according to a third aspect of the present invention is the power supply circuit according to the first or second aspect, wherein the first detection means is an output of the second drive means or an ambient temperature of the second switching element. Based on the above, an abnormality of the second driving means is detected. Thereby, the abnormality of the second driving means can be detected based on the output of the second driving means or the ambient temperature of the second switching element.

  The power supply circuit according to a fourth aspect of the present invention is the power supply circuit according to any one of the first to third aspects, wherein the second detection means is an output of the fourth drive means or the fourth switching. Based on the ambient temperature of the element, an abnormality of the fourth driving means is detected. Thereby, the abnormality of the fourth driving means can be detected based on the output of the fourth driving means or the ambient temperature of the fourth switching element.

  A power supply circuit according to a fifth aspect of the present invention is the power circuit according to any one of the first to fourth aspects, wherein the abnormality is detected to the user when the abnormality is detected by the first or second detecting means. Means. Thereby, when an abnormality of the second or fourth drive circuit is detected, the user can know that an abnormality has occurred in the circuit.

  A power supply circuit according to a sixth aspect of the present invention is connected to the DC power supply in parallel when an abnormality is detected by the first or second detection means in any one of the first to fifth aspects. And a stopping means for stopping energization of some of the electric loads. Thereby, when an abnormality in the second or fourth drive circuit is detected, the electric load can be reduced.

  According to the present invention, it is possible to realize a power supply circuit that can prevent a MOSFET from being adversely affected even when the MOSFET cannot be turned on due to a drive circuit failure or the like.

It is a figure which shows the structure of the power supply circuit which concerns on one embodiment. It is a figure which shows the structure of the power supply circuit which concerns on a modification.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
A power supply circuit according to an embodiment of the present invention is a power supply circuit for idle stop mounted on an idle stop vehicle.

FIG. 1 is a diagram illustrating a configuration of a power supply circuit according to the present embodiment.
As shown in the figure, the power supply circuit according to the present embodiment includes a battery 100, synchronous rectification booster circuits 200 and 300, an ECU 400, a display unit 500, and a relay 600. Alternatively, a voltage obtained by boosting this voltage by the booster circuits 200 and 300 is output to the electric loads 700 and 800 or the electric load 700. Here, the battery 100 is an example of a DC power source.

  The booster circuit 200 includes capacitors 201 and 202, a fuse 203, a shunt resistor 204, an inductor 205, MOSFETs 206 and 207, drive circuits 208 and 209, a detection circuit 210, and a control circuit 211. Here, the fuse 203 is an example of a first interrupting unit that interrupts energization between the battery 100 and the inductor 205 when an overcurrent flows. The inductor 205 is an example of a first inductor. The MOSFET 206 is an example of a first switching element, and the MOSFET 207 is an example of a second switching element in which a first diode is connected in parallel. The drive circuits 208 and 209 are examples of first and second driving units. The detection circuit 210 is an example of a first detection unit, and the control circuit 211 is an example of a control unit.

  The booster circuit 300 includes a fuse 301, a shunt resistor 302, an inductor 303, MOSFETs 304 and 305, drive circuits 306 and 307, and a detection circuit 308. Here, the fuse 301 is an example of a second interrupting unit that interrupts energization between the battery 100 and the inductor 303 when an overcurrent flows. The inductor 303 is an example of a second inductor. The MOSFET 304 is an example of a third switching element, and the MOSFET 305 is an example of a fourth switching element in which a second diode is connected in parallel. The drive circuits 306 and 307 are examples of third and fourth driving units. The detection circuit 308 is an example of a second detection unit.

  In the booster circuits 200 and 300, the capacitor 201 is connected in parallel to the battery 100, and one terminal of the capacitor 201 is connected to one terminal of the fuse 203 and one terminal of the fuse 301. The other terminal of the capacitor 201 is connected to the source terminal of the MOSFET 206, the source terminal of the MOSFET 304, and one terminal of the capacitor 202.

  The other terminal of the fuse 203 is connected to one terminal of the inductor 205 via the shunt resistor 204. The other terminal of the inductor 205 is connected to the drain terminal of the MOSFET 206 and the source terminal of the MOSFET 207.

  The other terminal of the fuse 301 is connected to one terminal of the inductor 303 via the shunt resistor 302. The other terminal of the inductor 303 is connected to the drain terminal of the MOSFET 304 and the source terminal of the MOSFET 305.

The drain terminal of the MOSFET 207 and the drain terminal of the MOSFET 305 are connected to the other terminal of the capacitor 202.
The drive circuit 208 outputs a drive voltage for turning on or off the MOSFET 206 to the gate terminal of the MOSFET 206 in accordance with a control signal from the control circuit 211. The drive circuit 209 outputs a drive voltage for turning on or off the MOSFET 207 to the gate terminal of the MOSFET 207 in accordance with a control signal from the control circuit 211.

  The drive circuit 306 outputs a drive voltage for turning on or off the MOSFET 304 to the gate terminal of the MOSFET 304 in accordance with a control signal from the control circuit 211. The drive circuit 307 outputs a drive voltage for turning on or off the MOSFET 305 to the gate terminal of the MOSFET 305 in accordance with a control signal from the control circuit 211.

  The detection circuit 210 detects an abnormality of the drive circuit 209 based on the output of the drive circuit 209, and outputs an abnormality detection signal when the abnormality is detected. For example, the detection circuit 210 detects an abnormality in the drive circuit 209 when the drive voltage output from the drive circuit 209 is different from the drive voltage output from the drive circuit 209 at the normal time.

  The detection circuit 308 detects an abnormality of the drive circuit 307 based on the output of the drive circuit 307, and outputs an abnormality detection signal when the abnormality is detected. For example, the detection circuit 308 detects an abnormality in the drive circuit 307 when the drive voltage output from the drive circuit 307 is different from the drive voltage output from the drive circuit 307 in a normal state.

  The control circuit 211 controls the drive circuits 208, 209, 306, and 307 based on the output signals of the detection circuits 210 and 308 and the voltage across the shunt resistors 204 and 302 under the control of the ECU 400. The operation of the control circuit 211 can be realized by software or hardware. When realized by software, the control circuit 211 includes a CPU and a memory, and the CPU reads and executes a control program stored in the memory.

  ECU 400 controls the entire system of the idle stop vehicle. Under the control of the ECU 400, the display unit 500 performs various displays such as notification to the driver (user) on an instrument panel (not shown). Relay 600 turns on or off energization of electric load 800 under the control of ECU 400. Note that some functions of ECU 400 and display unit 500 are examples of notification means, and some functions of ECU 400 and relay 600 are examples of stop means.

  The electrical loads 700 and 800 are a general term for electrical components for which it is desired that the supply voltage does not deviate from the operating range even when the voltage of the battery 100 temporarily decreases. Is an electric load related to the basic performance of the vehicle such as running, turning, and stopping, and the electric load 800 is an electric load not related to the basic performance of such a vehicle. For example, car navigation, audio, etc., which are not related to the basic performance of the vehicle, but when the normal operation temporarily stops due to a temporary drop in the supply voltage, the driver may feel uncomfortable. The electrical component is included in the electrical load 800.

  Next, as the operation of the power supply circuit according to the present embodiment, the normal operation in which the voltage of the battery 100 does not temporarily decrease and the engine start (including the engine restart) in which the voltage of the battery 100 temporarily decreases are included. ) Will be described.

  The operation at the time of starting the engine is a control signal for the ECU 400 that detects the engine starting operation (including the engine restarting operation) by the driver during the normal operation to start the operation at the time of engine starting. It starts by outputting to the circuit 211. Further, the operation at the time of starting the engine is terminated when the ECU 400 that has detected the start of the engine outputs a control signal for shifting to the normal operation to the control circuit 211.

First, the normal operation will be described.
In this operation, the control circuit 211 controls the drive circuits 208 and 306 to turn off the MOSFETs 206 and 304, and controls the drive circuits 209 and 307 to turn on the MOSFETs 207 and 305. As a result, the voltage of the battery 100 is output to the electric loads 700 and 800 as it is without being boosted by the booster circuits 200 and 300 at normal times.

  In normal times, even if the MOSFETs 207 and 305 are turned off, current can be passed through the body diodes 207a and 305a. However, when the MOSFETs 207 and 305 are turned on, the voltage drop in the MOSFETs 207 and 305 is reduced and the loss is reduced. Therefore, the MOSFETs 207 and 305 are turned on.

  On the other hand, when the detection circuit 210 outputs an abnormality detection signal during the normal operation, the control circuit 211 first outputs a signal for notifying the ECU 400 of the abnormality of the drive circuit 209. Receiving this signal, the ECU 400 controls the display unit 500 to cause an instrument panel (not shown) to perform a display for notifying the driver of an abnormality in the power supply circuit (drive circuit 209). This notification includes a notification that the power supply circuit needs to be repaired (unit replacement or the like). Next, the control circuit 211 does not change the control of the drive circuits 306 and 307, but changes the control of the drive circuits 208 and 209 as follows. That is, the control circuit 211 controls the drive circuit 209 to stop its operation and controls the drive circuit 208 to turn on the MOSFET 206. As a result, a current flows from the battery 100 to the MOSFET 206 via the fuse 203, the shunt resistor 204, and the inductor 205. Then, an overcurrent flows through the fuse 203, and the fuse 203 is eventually blown to interrupt the energization between the battery 100 and the inductor 205. When the control circuit 211 detects the interruption of energization based on the voltage across the shunt resistor 204, the control circuit 211 also controls the drive circuit 208 to stop its operation.

  By such an operation, when an abnormality of the drive circuit 209 is detected during the above-described normal operation, the voltage of the battery 100 is directly passed through the booster circuit 300 without passing through the booster circuit 200. 700 and 800 are output. In addition, the driver is notified of the abnormality of the power supply circuit.

  Note that if the voltage of the battery 100 is output to the electric loads 700 and 800 only through the booster circuit 300, there is a risk that the electrical components in the booster circuit 300 may be adversely affected (for example, damaged) due to the design of the power supply circuit. If there is, the ECU 400 that receives the signal notifying the abnormality of the drive circuit 209 controls to turn off the relay 600 instead of or together with the display for the notification. It is also possible to configure as described above. As a result, since the energization to the electric load 800 is turned off, the electric load is reduced, and the voltage of the battery 100 is output only to the electric load 700 via the booster circuit 300.

  Alternatively, when the detection circuit 308 instead of the detection circuit 210 outputs an abnormality detection signal during the normal operation described above, the control circuit 211 first outputs a signal notifying the ECU 400 of the abnormality of the drive circuit 307. To do. Receiving this signal, the ECU 400 controls the display unit 500 to cause an instrument panel (not shown) to display an indication for notifying the driver of an abnormality in the power supply circuit (drive circuit 307). This notification includes a notification that the power supply circuit needs to be repaired (unit replacement or the like). Next, the control circuit 211 does not change the control of the drive circuits 208 and 209, but changes the control of the drive circuits 306 and 307 as follows. That is, the control circuit 211 controls the drive circuit 307 to stop its operation and controls the drive circuit 306 to turn on the MOSFET 304. As a result, a current flows from the battery 100 to the MOSFET 304 via the fuse 301, the shunt resistor 302, and the inductor 303. Then, an overcurrent flows through the fuse 301, and the fuse 301 is eventually blown to interrupt the energization between the battery 100 and the inductor 303. When the control circuit 211 detects this interruption of energization based on the voltage across the shunt resistor 302, the control circuit 211 also controls the drive circuit 306 to stop its operation.

  By such an operation, when an abnormality of the drive circuit 307 is detected during the above-described normal operation, the voltage of the battery 100 is directly passed through the booster circuit 200 without passing through the booster circuit 300. 700 and 800 are output. In addition, the driver is notified of the abnormality of the power supply circuit.

  Note that if the voltage of the battery 100 is output to the electric loads 700 and 800 only through the booster circuit 200, the power supply circuit may be adversely affected (for example, damaged) due to the design of the power supply circuit. If there is, the ECU 400 that receives the signal notifying the abnormality of the drive circuit 307 controls to turn off the relay 600 instead of or together with the display for the notification. It is also possible to configure as described above. As a result, since the energization to the electric load 800 is turned off, the electric load is reduced, and the voltage of the battery 100 is output only to the electric load 700 via the booster circuit 200.

Next, the operation when starting the engine will be described.
In this operation, the control circuit 211 controls the drive circuits 208 and 307 to turn on the MOSFETs 206 and 305, thereby controlling the drive circuits 306 and 209 to turn off the MOSFETs 304 and 207 to control the drive circuits 208 and 307. When the MOSFETs 206 and 305 are turned off, the operation of controlling the drive circuits 306 and 209 and turning on the MOSFETs 304 and 207 is alternately repeated. However, at this time, a dead time is provided in which both MOSFETs 206 and 207 are not turned on at the same time so that both MOSFETs 304 and 305 are not turned on at the same time. Both dead times are set off. As a result, when the engine is started, the voltage of the battery 100 is boosted by the booster circuits 200 and 300, and the boosted voltage is output to the electric loads 700 and 800.

  On the other hand, when the detection circuit 210 outputs an abnormality detection signal during the operation at the time of starting the engine, the operation at the time of starting the engine is the same as the operation at the time of starting the engine. Thus, even when the drive circuit 209 is abnormal and, for example, the MOSFET 207 cannot be turned on, it can operate as a booster circuit because it can be energized through the body diode 207a. However, if the state is left as it is, the voltage drop in the MOSFET 207 increases and the loss increases, and the MOSFET 207 may be damaged in some cases. Therefore, when the operation at the time of starting the engine is completed and the operation is shifted to the normal operation, the control circuit 211 is performed when the detection circuit 210 outputs an abnormality detection signal during the normal operation. The operation is almost the same as the operation. That is, the control circuit 211 first outputs a signal that notifies the ECU 400 of an abnormality in the drive circuit 209. Receiving this signal, the ECU 400 controls the display unit 500 to cause an instrument panel (not shown) to display an indication for notifying the driver of an abnormality in the power supply circuit (drive circuit 209), and to turn on the relay 600. Control to turn off. The notification at this time includes notification that the power supply circuit needs to be repaired (unit replacement or the like). Next, the control circuit 211 controls the drive circuit 209 to stop its operation, and controls the drive circuit 208 to turn on the MOSFET 206. As a result, an overcurrent flows through the fuse 203, and the fuse 203 is eventually blown to interrupt the energization between the battery 100 and the inductor 205. When the control circuit 211 detects the interruption of energization based on the voltage across the shunt resistor 204, the control circuit 211 also controls the drive circuit 208 to stop its operation. Then, the following operation is performed as the operation at the time of starting the engine after the next time.

  The control circuit 211 controls the drive circuit 306 to turn off the MOSFET 305 when the drive circuit 306 is turned on to control the drive circuit 307, and controls the drive circuit 307 to control the drive circuit 307 when the MOSFET 304 is turned off. The operation of turning on the MOSFET 305 is repeated alternately. However, also at this time, a dead time is provided in which both MOSFETs 304 and 305 are turned off so that both MOSFETs are not turned on at the same time. The drive circuits 208 and 209 are controlled so as to stop their operations.

  If the drive circuit 209 is damaged during operation at the time of starting the engine due to such an operation, and the operation becomes abnormal, the voltage of the battery 100 is set to the voltage booster circuit 300 only at the next and subsequent engine start. The voltage is boosted by. In addition, since the power supply to the electric load 800 is turned off, the electric load is reduced, and the boosted voltage is output only to the electric load 700.

  Alternatively, when the detection circuit 308 outputs an abnormality detection signal instead of the detection circuit 210 during the operation at the time of engine startup, the operation at the time of engine startup is the operation at the time of engine startup (abnormality). The same operation as that before the detection signal is output) is performed. Thus, even when the drive circuit 307 is abnormal and, for example, the MOSFET 305 cannot be turned on, it can operate as a booster circuit because it can be energized through the body diode 305a. However, if this is left, the voltage drop in the MOSFET 305 increases and the loss increases, and the MOSFET 305 may be damaged in some cases. Therefore, when the operation at the time of engine start at this time is finished and the operation is shifted to the normal operation, the control circuit 211 is performed when the detection circuit 308 outputs an abnormality detection signal during the normal operation. The operation is almost the same as the operation. That is, the control circuit 211 first outputs a signal for notifying the abnormality of the drive circuit 307 to the ECU 400. Receiving this signal, the ECU 400 controls the display unit 500 to cause an instrument panel (not shown) to display an indication for notifying the driver of the abnormality of the power supply circuit (drive circuit 307), and to turn on the relay 600. Control to turn off. The notification at this time includes notification that the power supply circuit needs to be repaired (unit replacement or the like). Next, the control circuit 211 controls the drive circuit 307 to stop its operation and controls the drive circuit 306 to turn on the MOSFET 304. As a result, an overcurrent flows through the fuse 301, and the fuse 301 is eventually blown to interrupt the energization between the battery 100 and the inductor 303. When the control circuit 211 detects this interruption of energization based on the voltage across the shunt resistor 302, the control circuit 211 also controls the drive circuit 306 to stop its operation. Then, the following operation is performed as the operation at the time of starting the engine after the next time.

  The control circuit 211 controls the drive circuit 208 when the MOSFET 206 is turned on by controlling the drive circuit 208 to turn off the MOSFET 207, and controls the drive circuit 209 when the MOSFET 206 is turned off by controlling the drive circuit 208. The operation of turning on the MOSFET 207 is repeated alternately. However, also at this time, a dead time is provided in which both MOSFETs 206 and 207 are turned off so that both MOSFETs are not turned on at the same time. The drive circuits 306 and 307 are controlled so as to stop their operations.

  If the drive circuit 307 is damaged during operation at the time of starting the engine due to such an operation, and the operation becomes abnormal, the voltage of the battery 100 is set to only the booster circuit 200 at the next and subsequent start of the engine. The voltage is boosted by. In addition, since the power supply to the electric load 800 is turned off, the electric load is reduced, and the boosted voltage is output only to the electric load 700.

  As described above, according to the power supply circuit according to the present embodiment, even if the drive circuit 209 or 305 fails and the MOSFET 207 or 305 cannot be turned on, the fuse 203 or 301 is blown. As a result, no current flows through the body diode 207a or 305a, so that the MOSFET 207 or 305 can be prevented from being adversely affected. Even in such a case, since the operation of one of the booster circuits 200 and 300 is maintained, at least until the vehicle is repaired (unit replacement, etc.), The supply of electric power to the electric load 700 related to the basic performance can be maintained.

  In addition, according to the power supply circuit according to the present embodiment, by including the synchronous rectification booster circuits 200 and 300, it is possible to realize a low-loss and high-efficiency power supply circuit that can be reduced in size and cost.

The power supply circuit according to this embodiment can be modified as follows.
For example, the detection circuit 210 may be configured to detect an abnormality of the drive circuit 209 based on the ambient temperature of the MOSFET 207 instead of detecting an abnormality of the drive circuit 209 based on the output of the drive circuit 209. . Similarly, the detection circuit 308 may be configured to detect an abnormality of the drive circuit 307 based on the ambient temperature of the MOSFET 305 instead of detecting an abnormality of the drive circuit 307 based on the output of the drive circuit 307. It is.

FIG. 2 is a diagram showing the configuration of the power supply circuit configured as described above.
As shown in the figure, in this power supply circuit, a thermistor 221 is provided around the MOSFET 207, and the detection circuit 210 detects an abnormality of the drive circuit 209 based on the output of the thermistor 221 instead of the output of the drive circuit 209. The point that the thermistor 321 is provided around the MOSFET 305 and the detection circuit 308 detects the abnormality of the drive circuit 307 based on the output of the thermistor 321 instead of the output of the drive circuit 307 is shown in FIG. It is different from the power supply circuit shown in

  In this power supply circuit, when the MOSFET 207 cannot be turned on due to an abnormality in the drive circuit 209, a current always flows through the body diode 207a of the MOSFET 207, and the temperature of the MOSFET 207 rises. When a signal corresponding to the ambient temperature of the MOSFET 207 at this time is output by the thermistor 221, the detection circuit 210 detects an abnormality in the drive circuit 209 and outputs an abnormality detection signal. Similarly, for the drive circuit 307, the MOSFET 305, the detection circuit 308, and the thermistor 321, when the MOSFET 305 cannot be turned on due to an abnormality in the drive circuit 307, a current always flows through the body diode 305a of the MOSFET 305, The temperature of the MOSFET 305 rises. When a signal corresponding to the ambient temperature of the MOSFET 305 at this time is output by the thermistor 321, the detection circuit 308 detects an abnormality in the drive circuit 307 and outputs an abnormality detection signal.

Other configurations and operations are the same as those of the power supply circuit shown in FIG. Even with the power supply circuit having such a configuration, the same effect as that of the power supply circuit shown in FIG. 1 can be obtained.
Further, in the power supply circuit according to the present embodiment, one of the detection circuits 210 and 308 is driven based on the output of the drive circuit as shown in FIG. 1 by combining the configurations shown in FIGS. It is also possible to detect the abnormality of the circuit and to detect the abnormality of the drive circuit based on the output of the thermistor provided around the MOSFET as shown in FIG.

  Further, in the power supply circuit according to the present embodiment, the power supply to the electric load 800 is turned off by turning off the relay 600 under the control of the ECU. It is also possible to configure so that energization to is turned off.

In addition, the power supply circuit according to the present embodiment has a configuration including two booster circuits, but may be configured to include three or more booster circuits.
In this embodiment, an example in which the present invention is applied to an idle stop power supply circuit has been described. However, the present invention can also be applied to other power supply circuits including a synchronous rectification booster circuit.

  In the present embodiment, as described above, when the detection circuit 210 (or 308) outputs an abnormality detection signal during normal operation, first, the control circuit 211 sends the drive circuit 209 (or 307) to the ECU 400. The ECU 400 that outputs a signal notifying the abnormality and controlling the display so as to notify the driver of the abnormality and to turn off the relay 600, and then the control circuit 211 Control is performed so that the energization between the battery 100 and the inductor 205 (or 303) is cut off. Such a series of flow operations can be modified as follows.

  For example, when the detection circuit 210 (or 308) outputs an abnormality detection signal during normal operation, the control circuit 211 is controlled to cut off the energization between the battery 100 and the inductor 205 (or 303). At the same time, the ECU 400 outputs a signal notifying the abnormality of the drive circuit 209 (or 307) to the ECU 400, and the ECU 400 having received the signal causes the display to notify the driver of the abnormality or the relay 600. It is also possible to adopt a configuration for controlling to turn off.

  Alternatively, for example, when the detection circuit 210 (or 308) outputs an abnormality detection signal during normal operation, the control circuit 211 interrupts the energization between the battery 100 and the inductor 205 (or 303). A signal to the drive circuits 208, 209 (or 306, 307) that is a control signal of the control signal and a signal to notify the abnormality of the drive circuit 209 (or 307) to the ECU 400 are simultaneously output, and a signal to notify the abnormality is output. It is also possible to adopt a configuration in which the received ECU 400 performs control so that a display for notifying the driver of an abnormality is performed or the relay 600 is turned off.

  Further, in the present embodiment, as described above, when the detection circuit 210 (or 308) outputs an abnormality detection signal during operation at the time of engine start, the operation at the time of engine start at that time ends and the normal time First, the control circuit 211 outputs a signal notifying the abnormality of the drive circuit 209 (or 307) to the ECU 400, and the ECU 400 receiving the signal notifies the driver of the abnormality. The display 600 is controlled and the relay 600 is turned off, and then the control circuit 211 is controlled to cut off the energization between the battery 100 and the inductor 205 (or 303). In the operation at the time of starting, the control circuit 211 is controlled to perform the boosting operation only by the boosting circuit 300 (or 200). Such a series of flow operations can be modified as follows.

  For example, when the detection circuit 210 (or 308) outputs an abnormality detection signal during the operation at the time of engine start, when the operation at the time of engine start ends and the operation moves to the normal operation, The control circuit 211 controls the power supply between the battery 100 and the inductor 205 (or 303) to be cut off, and outputs a signal notifying the ECU 400 of the abnormality of the drive circuit 209 (or 307). The ECU 400 that has received the control controls the display so as to notify the driver of the abnormality, and the ECU 400 controls the relay 600 to be turned off in the operation after the next engine start. A configuration in which the circuit 211 is controlled to perform a boosting operation only by the boosting circuit 300 (or 200) may be employed.

  Alternatively, for example, when the detection circuit 210 (or 308) outputs an abnormality detection signal during operation when starting the engine, first, the control circuit 211 notifies the ECU 400 of an abnormality in the drive circuit 209 (or 307). The ECU 400 that receives the signal is controlled so that the display for notifying the driver of the abnormality is performed and the relay 600 is turned off. Next, the control circuit 211 controls the booster circuit 300 ( Alternatively, it is possible to adopt a configuration in which the step-up operation is controlled only by 200).

  In the present embodiment, the boosting operation by the boosting circuits 200 and 300 when the detection circuit 210 (or 308) does not output an abnormality detection signal during the operation at the time of starting the engine is as described above. 307 is controlled to turn on the MOSFETs 206 and 305, the drive circuits 306 and 209 are controlled to turn off the MOSFETs 304 and 207, and the drive circuits 208 and 307 are controlled to turn off the MOSFETs 206 and 305. The operation of turning on MOSFETs 304 and 207 by controlling 209 is repeated alternately. However, the step-up operation by the step-up circuits 200 and 300 is not limited to such an operation. For example, when the drive circuit 208 is controlled and the MOSFET 206 is turned on, the drive circuit 209 is controlled and the MOSFET 207 is turned off. When the drive circuit 208 is controlled to turn off the MOSFET 206, the drive circuit 209 is controlled to turn on the MOSFET 207, and the drive circuit 306 is controlled to turn on the MOSFET 304. The operation of controlling 307 to turn off the MOSFET 305 and controlling the drive circuit 306 to turn off the MOSFET 304 and controlling the drive circuit 307 to turn on the MOSFET 305 are repeated. To be possible.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various improvements and modifications can be made without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 100 Battery 200 Booster circuit 201, 202 Capacitor 203 Fuse 204 Shunt resistance 205 Inductor 206, 207 MOSFET
208, 209 Drive circuit 210 Detection circuit 211 Control circuit 221 Thermistor 300 Booster circuit 301 Fuse 302 Shunt resistor 303 Inductor 304, 305 MOSFET
306, 307 Drive circuit 308 Detection circuit 321 Thermistor 400 ECU
500 Display unit 600 Relay 700, 800 Electric load

Claims (6)

DC power supply,
A first switching element;
A first inductor provided between the DC power supply and the first switching element;
A second switching element provided between the first inductor and an electrical load;
A first diode connected in parallel to the second switching element;
A first shut-off means for shutting off energization between the DC power source and the first inductor due to an overcurrent flowing;
First driving means for driving the first switching element;
Second driving means for driving the second switching element;
First detecting means for detecting an abnormality of the second driving means;
A third switching element;
A second inductor provided between the DC power supply and the third switching element;
A fourth switching element provided between the second inductor and the electric load;
A second diode connected in parallel to the fourth switching element;
A second shut-off means for shutting off energization between the DC power source and the second inductor due to an overcurrent flowing;
Third driving means for driving the third switching element;
Fourth driving means for driving the fourth switching element;
Second detection means for detecting an abnormality of the fourth drive means;
Control means for outputting the voltage of the DC power supply or the voltage obtained by boosting the voltage of the DC power supply by driving the first to fourth switching elements by controlling the first to fourth driving means;
With
The control means includes
When an abnormality of the second drive means is detected by the first detection means, the first drive means is controlled to cause an overcurrent to flow through the first cutoff means, thereby Cutting off the power supply to the first inductor;
When an abnormality of the fourth drive means is detected by the second detection means, the third drive means is controlled to flow an overcurrent to the second cutoff means, thereby Cutting off the power supply to and from the second inductor;
A power supply circuit characterized by that. The control means includes
The first and second switching elements are configured to turn off the second switching element when the first switching element is turned on and turn on the second switching element when the first switching element is turned off. Controlling the driving means to turn off the fourth switching element when the third switching element is turned on, and to turn on the fourth switching element when the third switching element is turned off; By controlling the third and fourth driving means, the voltage of the DC power supply is boosted,
When an abnormality of the second drive means is detected by the first detection means, the first drive means is controlled to cause an overcurrent to flow through the first cutoff means, thereby After cutting off the power supply to the first inductor, the fourth switching element is turned off when the third switching element is turned on, and the fourth switching element is turned off when the third switching element is turned off. By controlling the third and fourth driving means so as to turn on the switching element, the voltage of the DC power source is boosted,
When an abnormality of the fourth drive means is detected by the second detection means, the third drive means is controlled to flow an overcurrent to the second cutoff means, thereby After shutting off the energization with the second inductor, the second switching element is turned off when the first switching element is turned on, and the second switching element is turned off when the first switching element is turned off. The voltage of the DC power supply is boosted by controlling the first and second driving means so as to turn on the switching element.
The power supply circuit according to claim 1. The first detecting means detects an abnormality of the second driving means based on an output of the second driving means or an ambient temperature of the second switching element;
The power supply circuit according to claim 1 or 2, The second detecting means detects an abnormality of the fourth driving means based on an output of the fourth driving means or an ambient temperature of the fourth switching element;
The power supply circuit according to any one of claims 1 to 3, wherein A notification means for notifying the user of an abnormality when an abnormality is detected by the first or second detection means;
The power supply circuit according to claim 1, further comprising: Stop means for stopping energization of a part of the electrical load connected in parallel to the DC power supply when an abnormality is detected by the first or second detection means,
The power supply circuit according to claim 1, further comprising:

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