JP2013110837A - Power system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power system that can shorten an update cycle of a duty signal for a DC-DC converter 12 and determine whether there is an anomaly in the power system.SOLUTION: A first control circuit 16 and a second control circuit 18 each generate duty signals such that on periods of switching elements Sp1, Sn1, Sp2, Sn2 do not overlap on the basis of duty signals output from the control circuits 16, 18, whose input includes a detection value of an output side voltage sensor 26. The detection values input into the first control circuit 16 and the second control circuit 18, respectively, are compared to determine whether or not there is an anomaly in the power system. If the determination finds an anomaly in the power system, on times of the duty signals output from the control circuit that corresponds to the shorter on times of the duty signals of the first control circuit 16 and the second control circuit 18 are doubled.

Description

  The present invention includes a control circuit that generates a ratio signal that defines a ratio of an ON time to one cycle of an ON state and an OFF state of the switching element, and the switching element based on the generated ratio signal The present invention relates to a power supply system including a DCDC converter whose output voltage is controlled by an on / off operation.

  Conventionally, as seen in, for example, Patent Documents 1 and 2 below, a time ratio signal (Duty signal) that defines a ratio of on-time to one cycle of an on state and an off state of a switching element is generated by a controller. There is known a power supply system including a DCDC converter in which an output voltage is controlled by an on / off operation of a switching element based on a duty signal.

  As a power supply system, as shown in Patent Document 3 below, a system including a plurality of DCDC converters connected in parallel is also known. Such a configuration is intended to improve the reliability of the power supply system or increase the maximum value of the supply current to the power supply destination of the power supply system.

JP 2006-94690 A JP 2006-101680 A JP 2007-318949 A

  By the way, it is conceivable to shorten the update period of the Duty signal for the purpose of improving the response of the output voltage of the DCDC converter or reducing the size of the components constituting the DCDC converter by increasing the switching speed. . However, there is a concern that the above-mentioned object cannot be achieved if the update cycle of the duty signal cannot be sufficiently shortened due to the limitation of the calculation speed of the controller that generates the duty signal.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a new power supply system capable of shortening the update period of the duty ratio signal of the DCDC converter.

  Hereinafter, means for solving the above-described problems and the operation and effects thereof will be described.

  The invention according to claim 1 has a control circuit for generating a ratio signal for defining a ratio of an ON time to one cycle of the ON state and the OFF state of the switching element, and is based on the generated ratio signal. In a power supply system including a DCDC converter in which an output voltage is controlled by an on / off operation of the switching element, a plurality of the control circuits are provided in one DCDC converter, and each of the plurality of control circuits is each of these control circuits. The time ratio signal is generated so that periods in which the switching elements are turned on do not overlap with each other on the basis of the time ratio signal output from.

  In the above invention, one DCDC converter includes a plurality of control circuits. Then, a time ratio signal is generated by each of these control circuits so that the periods during which the switching elements are turned on do not overlap each other based on the time ratio signals output from each of the plurality of control circuits. According to such a configuration, the update period of the duty ratio signal can be shortened. Thereby, the responsiveness of the output voltage of the DCDC converter can be enhanced, and the components constituting the DCDC converter can be reduced in size by setting the switching frequency to a high frequency.

  In the above invention, the power supply system may include one DCDC converter or a plurality of DCDC converters. Here, when there are a plurality of DCDC converters provided in the power supply system, each of the plurality of DCDC converters is provided with a plurality of control circuits.

  According to a second aspect of the present invention, in the first aspect of the present invention, the power supply system further includes a detection unit that detects a voltage or current of a current flow path of the power supply system, and each of the plurality of control circuits detects the detection unit. The time ratio signal is generated by inputting a value, the detection values of the detection means input to each of the plurality of control circuits are compared, and the time ratio signals generated by each of the plurality of control circuits are compared. And an abnormality determining means for determining whether an abnormality has occurred in the power supply system based on at least one of the comparisons.

  In the above invention, in each of the plurality of control circuits included in the DCDC converter, the duty ratio signal is generated with the detection value of the detection means as an input. Here, an abnormality may occur in the power supply system, such as an abnormality occurring in the detection means, a signal path connecting the detection means and the control circuit, and further in the control circuit. In this case, the duty ratio signal output from the control circuit is deviated from an appropriate signal, so that the output voltage of the DCDC converter is largely deviated from the assumed voltage, and various inconveniences may occur. Specifically, for example, if the output voltage of the DCDC converter becomes excessively higher than the assumed voltage, the output voltage of the DCDC converter greatly exceeds the rated voltage of the device to which power is supplied, and the reliability of the device may be reduced. is there. Further, for example, when the output voltage of the DCDC converter is excessively lower than the assumed voltage, there is a risk that the power supply to the power supply destination device is insufficient.

  Here, if an abnormality occurs in the power supply system, the detection value of the detection means used in the control circuit may be greatly deviated from the true value. Further, when an abnormality occurs in the power supply system, as described above, the time ratio signal generated in the control circuit may not be an appropriate signal. That is, when an abnormality occurs in this power supply system including a DCDC converter having a plurality of control circuits, the detection values of the detection means input to each of these control circuits are greatly different from each other, The time ratio signals generated by the above are greatly different.

  In view of these points, in the above invention, at least one of comparison between detection values of detection means input to each of a plurality of control circuits and comparison of time ratio signals generated by each of the plurality of control circuits. Based on the above, it is possible to appropriately determine whether or not an abnormality has occurred in the power supply system. As a result, even if an abnormality occurs in the power supply system, it is possible to appropriately take subsequent actions.

  In the above invention, the abnormality determination method based on the comparison between the detection values of the detection means is, for example, based on the fact that the absolute value of the difference between the detection values of the detection means exceeds the first specified value. A method of determining that an abnormality has occurred in the system can be employed. Further, as an abnormality determination method based on the comparison between the generated time ratio signals, for example, based on the fact that the absolute value of the difference between the generated time ratio signals exceeds a second specified value, A method for determining that an abnormality has occurred can be employed.

  According to a third aspect of the present invention, in the second aspect of the present invention, when the abnormality determination means determines that an abnormality has occurred in the power supply system, the time ratio generated by each of the plurality of control circuits. The selection means for selecting the time ratio signal with the shortest on-time among the signals, the on-time extension means for extending the on-time of the time ratio signal selected by the selection means, and the on-time extension means It further comprises an abnormal time operation means for turning on and off the switching element by a time ratio signal with a long on time.

  In the above invention, when it is determined that an abnormality has occurred in the power supply system, the time ratio signal with the shortest ON time is selected from the time ratio signals generated by each of the plurality of control circuits. Then, the ON time of the selected time ratio signal is lengthened and the switching element is turned on / off by the time ratio signal of which the on time is lengthened. According to such a configuration, it is possible to suppress the occurrence of a situation in which the output voltage of the DCDC converter becomes excessively higher than the assumed voltage, and it is also possible to suppress the occurrence of insufficient power supply to the power supply destination of the power supply system. .

  According to a fourth aspect of the present invention, in the second aspect of the present invention, three or more control circuits are provided in one DCDC converter, and the abnormality determination means determines that an abnormality has occurred in the power supply system. A selection means for selecting a time ratio signal having the largest number of on-times that are the same among the time ratio signals generated by each of the three or more control circuits; An on-time extension means for extending the on-time of the time ratio signal; and an abnormal time majority operation means for turning on and off the switching element by the time ratio signal having the on-time extended by the on-time extension means. It is characterized by that.

  In the above invention, when it is determined that an abnormality has occurred in the power supply system, among the time ratio signals generated by each of the three or more control circuits, the time ratio signal having the same number of on-times is the same. select. Then, the ON time of the selected time ratio signal is lengthened and the switching element is turned on / off by the time ratio signal of which the on time is lengthened. According to the above-described invention, even when an abnormality occurs in the power supply system, the switching element can be turned on / off by a normal time ratio signal having a high probability of being normal. Thereby, the fall of the reliability of a power supply system can be suppressed suitably, and generation | occurrence | production of the insufficient power supply with respect to the electric power feeding destination of a power supply system can also be suppressed.

  In the above invention, the three or more control circuits are not limited to a control circuit having a circuit configuration capable of transmitting a time ratio signal to the switching element after the time ratio signal is generated, and the time ratio signal is supplied to the switching element. A control circuit having a circuit configuration that cannot be transmitted may also be included.

  The invention according to claim 5 is the invention according to claim 4, wherein at least two of the three or more control circuits and at least two are capable of transmitting the time ratio signal to the switching element. Is impossible to transmit the time ratio signal to the switching element, and the abnormality determination means causes abnormality only in the control circuit that cannot transmit the time ratio signal to the switching element among the three or more control circuits. If it is determined that the time ratio signal is transmitted to the switching element from the control circuit capable of transmitting the time ratio signal to the switching element without increasing the ON time of the ratio signal. The apparatus further comprises a continuous operation means for continuing the transmission of the duty ratio signal.

  In the above invention, the control circuit in which the ratio signal cannot be transmitted to the switching element is included in three or more control circuits. Here, an abnormality of the control circuit, which cannot be transmitted, may occur as an abnormality of the power supply system. In this case, among the time ratio signals generated by each of the three or more control circuits, the time ratio signal having the largest number of ON times that are identical to each other is generated by each of the control circuits that can be transmitted. It is a duty ratio signal. That is, the time ratio signal generated by the control circuit capable of transmission is highly likely to be normal. In view of this point, in the above-described invention, when it is determined that an abnormality has occurred only in the control circuit that cannot transmit, the time ratio signal that is likely to be normal and is generated by each of the control circuits that can transmit Is continuously transmitted to the switching element.

  A sixth aspect of the present invention provides the control circuit according to any one of the third to fifth aspects, wherein the control circuit other than the control circuit generates the time ratio signal selected by the selection means from among the plurality of control circuits. Further comprising signal blocking means for blocking the transmission of the time ratio signal from the switching element to the switching element, and the on-time extending means is assumed to be lowered by blocking the transmission of the time ratio signal by the signal blocking means. The ON time is lengthened so that the power supplied to the DCDC converter can be compensated.

  In the above invention, by increasing the ON time in the above-described aspect, it is possible to suitably avoid shortage of power supply to the power supply destination of the power supply system even when an abnormality occurs in the power supply system.

  The invention according to claim 7 is the invention according to any one of claims 1 to 6, wherein the power supply system is mounted on a vehicle, and the vehicle includes a high-voltage-side vehicle-mounted load and the high-voltage-side vehicle-mounted load. And a high voltage battery serving as a power supply source of the DCDC converter.

  In the said invention, the high voltage | pressure side vehicle-mounted load (for example, main machine rotary machine, the electric compressor with which an air conditioner is equipped) and the power supply source of both DCDC converters are high voltage | pressure batteries. Here, when the required power of the high-voltage side vehicle-mounted load varies, there is a concern that the voltage of the high-voltage battery varies and the output voltage of the DCDC converter varies. In particular, when the required power of the high-voltage side vehicle-mounted load is suddenly changed, there is a concern that the fluctuation of the output voltage of the DCDC converter becomes large due to the remarkable fluctuation of the voltage of the high-voltage battery. For this reason, the said invention in which the fluctuation | variation of the said output voltage can become remarkable has the merit provided with the invention specific matter of the invention of Claim 1 which can improve the adjustment precision of an output voltage by shortening the update period of a time ratio signal. large.

The lineblock diagram of the power supply system concerning a 1st embodiment. The functional block diagram regarding the control processing of the DCDC converter concerning the embodiment. 6 is a flowchart showing a procedure of abnormality determination processing according to the embodiment. The time chart which shows an example of the abnormality determination process concerning the embodiment. The block diagram of the power supply system concerning 2nd Embodiment. The time chart which shows an example of the abnormality determination process concerning the embodiment. The time chart which shows an example of the abnormality determination process concerning the embodiment. The block diagram of the power supply system concerning 3rd Embodiment. The time chart which shows an example of the abnormality determination process concerning the embodiment.

(First embodiment)
Hereinafter, a first embodiment in which a power supply system according to the present invention is applied to a hybrid vehicle will be described with reference to the drawings.

  FIG. 1 shows the overall configuration of the power supply system according to the present embodiment.

  The illustrated high voltage battery 10 is a power supply source such as a rotating machine (motor generator) (not shown) as an in-vehicle main machine and an electric compressor provided in an air conditioner (not shown), for example, a predetermined high voltage of several hundred volts or more. Is a storage battery. Incidentally, as the high voltage battery 10, for example, a lithium ion storage battery or a nickel metal hydride storage battery can be employed.

  The high voltage battery 10 can be connected to the DCDC converter 12. The DCDC converter 12 includes a parallel connection body (full bridge circuit) of a series connection body of a pair of switching elements Sp1 and Sn1 and a series connection body of a pair of switching elements Sp2 and Sn2, a transformer 14, and a plurality of control circuits (first circuit). A control circuit 16 and a second control circuit 18) are provided. Specifically, the DCDC converter 12 is configured such that these components are mounted on a circuit board (for example, a single circuit board), and the circuit board is housed in a casing (case), thereby stepping down the voltage of the high-voltage battery 10. Output. Here, in the present embodiment, the single DCDC converter 12 is provided with a plurality of control circuits in order to improve the reliability of the power supply system. In the present embodiment, N-channel MOS transistors are assumed as the switching elements Sp1, Sn1, Sp2, and Sn2.

  The input terminals (drains) of the switching elements Sp1 and Sp2 on the high potential side are connected to the positive electrode side of the high voltage battery 10, and the output terminals (sources) of the switching elements Sn1 and Sn2 on the low potential side are the negative electrode side of the high voltage battery 10. It is connected to the. A free wheel diode (not shown) is connected between the input / output terminals of the switching elements Sp1, Sn1, Sp2, and Sn2.

  Both ends of the primary side coil 14a of the transformer 14 are connected to the connection point of the pair of switching elements Sp1 and Sn1 and the connection point of the pair of switching elements Sp2 and Sn2, respectively.

  Both ends of the secondary coil 14b of the transformer 14 are connected to the anode sides of the diodes RD1 and RD2, and the cathode sides of the diodes RD1 and RD2 are short-circuited. The diodes RD1 and RD2 are connected to a smoothing circuit 20 (LC filter) including a reactor 20a and a capacitor 20b.

  The primary sides of the high-voltage battery 10 and the DCDC converter 12 constitute an in-vehicle high-voltage system and are insulated from the ground line GL connected to the case of the DCDC converter 12. On the other hand, the secondary side of the DCDC converter 12 constitutes an in-vehicle low-voltage system that operates using the ground line GL as a reference potential.

  For this reason, in this embodiment, the midpoint tap mt of the secondary side coil 14b of the transformer 14 is connected to the ground line GL. According to such a configuration, the diodes RD1 and RD2 are configured such that the high-potential side switching element Sp1 and the low-potential side switching element Sn2 are turned on, or the high-potential side switching element Sp2 and the low-potential side switching element Sn1. Depending on whether is turned on, the voltage of “½” of the voltage across the secondary coil 14b is alternately output. The midpoint tap mt is a terminal connected to the center of the secondary side coil 14b of the transformer 14 (a midpoint that is a point equidistant from both terminals).

  On the primary side of the DCDC converter 12, an input side voltage sensor 22 for detecting the input voltage VH of the full bridge circuit and an input side current sensor 24 for detecting an input current IH flowing through the primary side coil 14a of the transformer 14 are provided. Is provided. Further, an output side voltage sensor 26 that detects an output voltage of the DCDC converter 12 (an output voltage from the smoothing circuit 20) is provided on the secondary side of the DCDC converter 12.

  A pair of output sides of the DCDC converter 12 are connected to a parallel connection body of the low voltage battery 28, the vehicle ECU 30, and the vehicle load 32 (excluding the vehicle ECU 30). The low-voltage battery 28 is a storage battery (for example, a lead storage battery) that constitutes a part of the low-voltage system and outputs a predetermined low voltage (for example, 12 V) lower than the voltage of the high-voltage battery 10. The in-vehicle load 32 includes, for example, an air conditioner (more specifically, an air blower fan, a heater for heating, etc.), a headlight, and an actuator for driving an engine (fuel injection) as an in-vehicle main unit. Valve etc.).

  The vehicle ECU 30 includes a control circuit that is higher than the first control circuit 16 and the second control circuit 18 (upstream when a user request input from a user interface such as an accelerator pedal is the most upstream). It is a device, and has a function of supervising vehicle control while using the low voltage battery 28 as a power supply source. The reference potential of the vehicle ECU 30, the first control circuit 16, and the second control circuit 18 is the potential of the ground line GL. In addition, the vehicle ECU 30 includes a voltage sensor 30 a that detects the output voltage of the DCDC converter 12.

  The vehicle ECU 30 is supplied with electric power from the low-voltage battery 28 when it is determined that the vehicle is allowed to travel by the user, and outputs a common operation signal to the DCDC converter 12 and the vehicle-mounted load 32. Here, in the present embodiment, whether or not the vehicle is permitted to travel is determined by whether or not the ignition switch 34 is turned on by the user.

  Each of the first control circuit 16 and the second control circuit 18 uses the low voltage battery 28 as a power supply source, and supplies power to the battery, the vehicle ECU 30 and the vehicle load 32 via the switching circuit 36. The switching elements Sp1, Sn1, Sp2, and Sn2 are operated. Specifically, each of the first control circuit 16 and the second control circuit 18 uses the detection values of the input-side voltage sensor 22, the input-side current sensor 24, and further the output-side voltage sensor 26 as analog signals for a predetermined period. AD converters 16a and 18a for converting into digital signals, arithmetic processing units 16b and 18b for performing various arithmetic processes related to operations of the switching elements Sp1, Sn1, Sp2 and Sn2, timer circuits 16c and 18c, arithmetic processing units 16b and 18b Are provided with output ports 16d and 18d for outputting the calculation results to the outside and interfaces 16e and 18e for exchanging information between the first and second control circuits 16 and 18.

  The high-pressure system and the low-pressure system are insulated by an insulating element (not shown) (for example, a photocoupler as an optical insulating element or a pulse transformer as a magnetic insulating element), and switching elements Sp1, Sn1, Sp2, and Sn2 A duty ratio signal for turning on / off the signal is transmitted to these switching elements through the insulating element in the switching circuit 36. The detection values of the input side voltage sensor 22 and the input side current sensor 24 are input to the AD conversion units 16a and 18a through the insulating elements.

  Next, the control processing of the DCDC converter 12 executed by the arithmetic processing units 16b and 18b will be described with reference to FIG. Specifically, FIG. 2 is a functional block diagram of control processing of the DCDC converter 12 according to the present embodiment.

  The voltage deviation calculation unit B1 calculates a deviation ΔVL between the output voltage VL of the DCDC converter 12 detected by the output side voltage sensor 26 and the target voltage VREF. Specifically, the deviation ΔVL is calculated as a value obtained by subtracting the output voltage VL from the target voltage VREF. Incidentally, in the above processing, instead of the detection value of the output side voltage sensor 26, a sensor for detecting the voltage at both ends of the low voltage battery 28 and the vehicle load 32 may be provided, and the detection value of this sensor may be used.

  The voltage feedback control unit B2 calculates an operation amount (Duty) for performing feedback control of the output voltage VL of the DCDC converter 12 to the target voltage VREF by proportional-integral control (PI control) based on the deviation ΔVL. Here, Duty is the ratio “Ton / Tα” of the on-time Ton of the switching element to one cycle Tα of the on-state and off-state of the switching element. In other words, the larger the Duty, the longer the on-time Ton of the switching element.

  The input voltage operation amount calculation unit B3 calculates a base value DB of the upper limit value (guard value) of the duty based on the input voltage VH detected by the input side voltage sensor 22. Specifically, the base value DB is calculated to be smaller as the input voltage VH is higher.

  The voltage change calculation unit B4 calculates the change amount of the input voltage VH (input voltage change amount ΔVH). Specifically, the input voltage change amount ΔVH is calculated as a value obtained by subtracting the detection value of the input side voltage sensor 22 AD-converted in the previous processing cycle from the detection value of the input-side voltage sensor 22 AD-converted in the current processing cycle. do it.

  The correction amount calculation unit B5 calculates the correction amount ΔDuty of the base value DB output from the input voltage operation amount calculation unit B3 based on the input voltage change amount ΔVH. Specifically, the correction amount ΔDuty is calculated so that the base value DB output from the input voltage manipulated variable calculation unit B3 becomes smaller as the input voltage change amount ΔVH is larger than 0, and the input voltage change amount ΔVH is smaller than 0. The correction amount ΔDuty that increases the base value DB output from the input voltage operation amount calculation unit B3 is calculated. In this processing, due to the large increase in the input voltage VH between the calculation timings of the calculation processing units 16b and 18b, the duty output from the DUTY selection unit B10 described later becomes excessively large with respect to an appropriate value. This is a process for avoiding this. In other words, in a situation where the input voltage VH greatly increases, the guard value calculated by the input voltage operation amount calculation unit B3 at the previous calculation timing increases from the appropriate guard value to the larger side as time elapses from the previous calculation timing. There is concern about deviation. For this reason, in order to dispel such concerns, the correction amount ΔDuty of the base value DB calculated by the input voltage operation amount calculation unit B3 is calculated in the above manner.

  The addition unit B6 calculates a guard value as an addition value of the base value DB output from the input voltage operation amount calculation unit B3 and the correction amount ΔDuty.

  The output current calculation unit B7 calculates the output current IL of the DCDC converter 12 based on the input current IH detected by the input side current sensor 24.

  The current deviation calculation unit B8 calculates a deviation ΔIL between the output current IL and the current limit value IREF. Specifically, the deviation ΔIL is calculated as a value obtained by subtracting the output current IL from the current limit value IREF. The current limit value IREF may be set to an upper limit value of a current that can maintain the reliability of the DCDC converter 12 (more specifically, an element of a current flow path in the DCDC converter 12).

  The constant current control unit B9 calculates a duty for performing feedback control of the output current IL of the DCDC converter 12 to the current limit value IREF by PI control based on the deviation ΔIL.

  The DUTY selection unit B10 performs a process of selecting the minimum value among the Dutys output from the voltage feedback control unit B2 and the constant current control unit B9 and outputting them as Duty signals from the output ports 16d and 18d. When the minimum value is larger than the guard value output from the adding unit B6, processing for outputting the guard value from the output ports 16d and 18d is performed.

  According to such a configuration, until the output current IL of the DCDC converter 12 exceeds the current limit value IREF, the duty is reduced as the output voltage VL is higher by the voltage feedback control (the on-time Ton of the switching element is shortened). It becomes. On the other hand, when the output current IL of the DCDC converter 12 exceeds the current limit value IREF, the output current IL of the DCDC converter 12 is limited by the current limit value IREF by constant current control, so that the output voltage VL is lowered. . That is, the DCDC converter 12 has a constant current drooping characteristic.

  Next, a logic circuit that connects the output port 16d of the first control circuit 16 and the output port 16d of the second control circuit 18 and the switching circuit 36 will be described with reference to FIG.

  The duty signals corresponding to the switching elements Sp1, Sn1, Sp2, and Sn2 calculated by the arithmetic processing unit 16b of the first control circuit 16 are respectively output from the AND circuits 38p1, 38n1, 38p2, and 38n2 via the output port 16d. Is input. The AND circuits 38p1, 38n1, 38p2, and 38n2 receive the first determination signal output from the output port 18d of the second control circuit 18, respectively.

  The duty signals corresponding to the switching elements Sp1, Sn1, Sp2, and Sn2 calculated by the arithmetic processing unit 18b of the second control circuit 18 are respectively output from the AND circuits 40p1, 40n1, 40p2, and 40n2 via the output port 18d. Is input. The AND circuit 40p1, 40n1, 40p2, 40n2 receives a second determination signal output from the output port 16d of the first control circuit 16.

  The output signals of the AND circuits 38p1, 38n1, 38p2, and 38n2 and the output signals of the AND circuits 40p1, 40n1, 40p2, and 40n2 are input to the OR circuits 42p1, 42n1, 42p2, and 42n2, respectively. .

  The output signals of the OR circuits 42p1, 42n1, 42p2, and 42n2 are transmitted to the switching control terminals (gates) of the switching elements Sp1, Sn1, Sp2, and Sn2 through the switching circuit 36.

  In such a configuration, the logic of the first determination signal is set to “L”, whereby transmission of the Duty signal from the first control circuit 16 to the switching circuit 36 is blocked. Further, since the logic of the second determination signal is set to “L”, transmission of the Duty signal from the second control circuit 18 to the switching circuit 36 is blocked.

  Here, adopting such a logic circuit shortens the update period of the Duty signal, and switches the operation mode of the switching elements Sp1, Sn1, Sp2, and Sn2 to perform fail-safe when an abnormality occurs in the power supply system. Because.

  Specifically, first, shortening of the duty update period of the switching element will be described. The switching element is turned on by the duty signal output from each of the first control circuit 16 and the second control circuit 18. A control logic that generates a duty signal by each of the control circuits 16 and 18 is employed so that the periods do not overlap each other. With such a control logic, a duty signal for alternately turning on the switching element is output from each of the first control circuit 16 and the second control circuit 18. As a result, the duty update cycle can be shortened.

  Next, the abnormality determination process of the power supply system according to the present embodiment will be described with reference to FIG. Specifically, FIG. 3 shows a procedure of control processing of the DCDC converter 12 including the abnormality determination processing according to the present embodiment. This process is triggered by the input of an operation signal from the vehicle ECU 30 to the timer circuits 16c and 18c, based on the count values of the timer circuits 16c and 18c, and the first control circuit 16 and the second control circuit 18, respectively. Are repeatedly executed in the same processing cycle.

  In the present embodiment, a series of control processing of the DCDC converter 12 (AD conversion processing, arithmetic processing, output setting processing, communication processing described later) executed by each of the first control circuit 16 and the second control circuit 18. And abnormality determination processing) contents are the same. Therefore, in FIG. 3, the first control circuit 16 will be mainly described.

  In this series of processing, first, in step S10, AD conversion processing for converting the input voltage VH, the input current IH, and the output voltage VL as analog signals into digital signals is performed in the AD conversion unit 16a. Hereinafter, the input voltage VH, the input current IH, and the output voltage VL converted into digital signals are referred to as AD conversion values.

  In subsequent step S12, based on the AD conversion value, an arithmetic process (the process in FIG. 2) for calculating Duty (on time Ton) corresponding to the switching elements Sp1, Sn1, Sp2, and Sn2 is performed.

  In the subsequent step S14, an output setting process is performed to output the duty signal corresponding to each of the switching elements Sp1, Sn1, Sp2, and Sn2 from the output port 16d. This processing uses the PWM function (function to output a pulse of a predetermined cycle and a predetermined duty) that is a function of the timer circuit 16c, and outputs the duty signal generated in the current processing cycle in the next processing cycle. It is a process for making it.

  In the subsequent step S16, the abnormality determination parameter P corresponding to the current processing cycle is transmitted to the second control circuit 18 via the interface 16e, and the latest past abnormality determination parameter in the second control circuit 18 is transmitted. Communication processing for receiving P from the second control circuit 18 via the interface 16e is performed. Here, in this embodiment, the AD conversion values of the input voltage VH, the input current IH, and the output voltage VL are used as the abnormality determination parameter P.

  In the subsequent step S18, it is determined whether or not the absolute value of the difference between the abnormality determination parameter P corresponding to the first control circuit 16 and the abnormality determination parameter P corresponding to the second control circuit 18 is larger than the threshold value γ. An abnormality determination process for determining is performed.

  Specifically, the abnormality determination process based on the difference between the output voltages VL will be described as an example. The output voltage VL AD-converted by the first control circuit 16 and the output AD-converted by the second control circuit 18 When it is determined that the absolute value of the difference from the voltage VL is larger than the threshold value γ, the output side voltage sensor 26 is abnormal, or the signal path connecting the output side voltage sensor 26 and the AD converter 16a is abnormal (for example, disconnection). It is determined that an abnormality in the power supply system has occurred, including an abnormality in the AD conversion unit 16a, an abnormality in the signal path connecting the AD conversion unit 16a and the arithmetic processing unit 16b (for example, disconnection), and an abnormality in the arithmetic processing unit 16b. .

  In addition to the above-described abnormality of the power supply system, there is also an abnormality that temporarily occurs in the power supply system. As this temporary abnormality, for example, there is an abnormality in which data in a memory (RAM) included in the control circuit changes (becomes) due to external noise (electromagnetic wave or the like).

  Further, since the execution start timings of the abnormality determination processes of the first control circuit 16 and the second control circuit 18 are not synchronized, the threshold value γ is used for abnormality determination corresponding to the first control circuit 16. The parameter P and the abnormality determination parameter P corresponding to the second control circuit 18 are set from the viewpoint of being able to determine whether or not they are substantially the same. Hereinafter, the setting of the threshold γ will be described.

  The input voltage VH and the input current IH of the DCDC converter 12 fluctuate due to fluctuations in required power of a motor generator or the like that uses the high-voltage battery 10 as a power supply source. In response to this, the output voltage VL and the output current IL of the DCDC converter 12 also vary. For this reason, for example, the threshold γ is set based on the maximum fluctuation amount of the AD conversion value assumed in the AD conversion processing execution interval of each control circuit, and more specifically, slightly larger than the maximum fluctuation amount. What is necessary is just to set as a value. By the way, the maximum fluctuation amount in the situation where the load torque acting on the driving wheel suddenly changes during driving of the motor generator, such as the situation where the slip is canceled immediately after the driving wheel slips temporarily on the frozen road surface. It is conceivable to set the fluctuation amount of the AD conversion value.

  If an affirmative determination is made in step S18, it is determined that an abnormality has occurred in the power supply system, and the process proceeds to step S20. In step S20, it is determined whether the on-time Ton corresponding to the first control circuit 16 calculated in step S14 is shorter than the on-time Ton corresponding to the second control circuit 18. Here, the on time Ton corresponding to the second control circuit 18 may be calculated based on the AD conversion value received from the second control circuit 18, or the on time calculated by the second control circuit 18. It may be a received value of Ton.

  If an affirmative determination is made in step S20, the process proceeds to step S22, in which the logic of the second determination signal is inverted from “H” to “L” and the duty signal calculated by the calculation process in step S12 is performed. A process for increasing the on-time Ton is performed. First, the logic inversion process of the second determination signal will be described. According to this process, the logic of the output signal of the AND circuits 40p1, 40n1, 40p2, and 40n2 is forcibly set to “L”, and the second control is performed. Transmission of the duty signal from the circuit 18 to the switching circuit 36 is cut off. That is, the first control circuit 16 is selected as a control circuit for operating the switching elements Sp1, Sn1, Sp2, and Sn2 out of the first control circuit 16 and the second control circuit 18.

  Further, the processing for extending the on-time Ton will be described. This processing is the power supplied to the DCDC converter 12 that is assumed to be reduced by the transmission of the duty signal from the second control circuit 18 to the switching circuit 36 being cut off. Is a process for compensating for In the present embodiment, a process of doubling the on-time Ton of the duty signal calculated by the calculation process of step S12 is performed.

  Incidentally, in the present embodiment, information that the logic of the second determination signal is inverted to “L” is transmitted from the first control circuit 16 to the second control circuit 18 via the interfaces 16e and 18e. Thus, also in the second control circuit 18, a process is performed in which the duty on-time Ton calculated by the calculation process of the control circuit is doubled. The extension of the on-time Ton in the first and second control circuits 16 and 18 is continued until it is determined that the logic of the second determination signal is inverted to “H”.

  In this step, it is desirable to perform processing for notifying the vehicle ECU 30 that an abnormality has occurred in the power supply system. Then, in the vehicle ECU 30 that has received the notification that an abnormality has occurred in the power supply system, for example, a notification process for notifying the user that the abnormality has occurred is performed, or the use of the electric power of the low-voltage battery 28 is restricted. What is necessary is just to process.

  If a negative determination is made in steps S18 and S20, or if the process in step S22 is completed, the series of processes is temporarily terminated.

  FIG. 4 shows an example of abnormality determination processing of the power supply system according to the present embodiment. Specifically, FIG. 4A shows the transition of the output state of the operation signal from the vehicle ECU 30, and FIGS. 4B-1 to 4B-4 show the operation state of the first control circuit 16. 4 (c-1) to 4 (c-4) show the transition of the operation state of the second control circuit 18, and FIG. 4 (d) shows the transition from the switching circuit 36 to the switching element. The transition of the duty signal. More specifically, FIG. 4B-1 shows the transition of the counter value of the timer circuit 16c, FIG. 4B-2 shows the transition of the processing contents of the first control circuit 16, and FIG. b-3) shows the transition of the output state of the Duty signal from the first control circuit 16 (output port 16d), and FIG. 4B-4 shows the transition of the output state of the second judgment signal. . 4 (c-1) to 4 (c-3) correspond to FIG. 4 (b-1) to FIG. 4 (b-3), and FIG. The transition of the output state of the determination signal of 1 is shown. In FIG. 4, the transition of the duty signal corresponds to one of the four switching elements provided in the DCDC converter 12.

  In the illustrated example, the start timing of a series of control processes of the DCDC converter 12 by the second control circuit 18 is delayed by a half process cycle from the start timing of the series of control processes by the first control circuit 16. . According to such a configuration, a logic “H” duty signal is alternately output from each of the first control circuit 16 and the second control circuit 18. Thereby, as shown in FIG. 4D, the switching cycle Tsw of the DCDC converter 12 is equal to the one cycle Tα of the on state and the off state corresponding to the first control circuit 16 and the second control circuit 18, respectively. It becomes half. That is, as described above, the update cycle of the Duty signal is shortened and the switching frequency is set to a high frequency.

  In order to realize such a configuration, at time t1 when the operation signal is output from the vehicle ECU 30, counting up by the timer circuit 16c of the first control circuit 16 and the timer circuit 18c of the second control circuit 18 is started. . Thereafter, the first control circuit 16 sets the time interval at which the timer circuit 16c is reset as one processing cycle (time t1 to t3, t3 to t5, t5 to t7, t7 to t9, etc.) in the first control circuit 16. A series of control processing of the DCDC converter 12 is performed. Further, the time interval at which the timer circuit 18c is reset is defined as one processing cycle (time t2 to t4, t4 to t6, t6 to t8, etc.) in the second control circuit 18 by the second control circuit 18 in the DCDC converter 12. A series of control processing is performed.

  Specifically, abnormality determination processing is performed by the first control circuit 16 that has received the AD conversion value of the second control circuit 18 in the processing cycle of the first control circuit 16 from time t1 to time t3. As a result, it is determined that there is no abnormality in the power supply system, and the Duty signal output from the first control circuit 16 is transmitted to the switching circuit 36 in the next processing cycle t3 to t5. After that, also in each processing cycle (time t3 to t5, t5 to t7, t7 to t9) of the first control circuit 16, it is not determined that an abnormality has occurred in the power supply system by the abnormality determination process.

  On the other hand, in the processing cycle of the second control circuit 18 from time t2 to t4, abnormality determination processing is performed by the second control circuit 18 that has received the AD conversion value of the first control circuit 16. As a result, it is determined that there is no abnormality in the power supply system, and the Duty signal output from the second control circuit 18 is transmitted to the switching circuit 36 in the next processing cycle t4 to t6.

  Thereafter, in the processing cycle of the second control circuit 18 from time t4 to t6, a temporary abnormality occurs in the power supply system, so that the latest past AD conversion value received from the first control circuit 16 and the second The second control circuit 18 determines that the absolute value of the difference from the AD conversion value of the control circuit 18 exceeds the threshold γ. Thereby, it is determined that an abnormality occurs in the power supply system.

  Further, it is determined that the on-time Ton of the second control circuit 18 is shorter than the most recent on-time Ton of the first control circuit 16. For this reason, at time t6, the logic of the first determination signal is inverted from “H” to “L”, whereby the transmission of the Duty signal from the first control circuit 16 to the switching circuit 36 is cut off.

  Furthermore, a process is performed in which the on-time Ton of the Duty signal calculated by the calculation process of the second control circuit 18 at times t4 to t6 is doubled. As a result, after time t6, although the switching cycle Tsw is doubled, the on-time Ton of the Duty signal output from the second control circuit 18 is doubled. In the figure, the on-time Ton before the on-time Ton is extended is indicated by a one-dot chain line.

  Incidentally, after time t7, the on-time Ton of the Duty signal calculated by the arithmetic processing of the first control circuit 16 is also doubled. Further, the output of the operation signal from the vehicle ECU 30 is stopped at time t10, and then the processing of the first control circuit 16 and the second control circuit 18 is stopped.

  As described above, in the present embodiment, the DCDC converter 12 includes the first control circuit 16 and the second control circuit 18, and the above-described series of control processing of the DCDC converter 12 is performed in these control circuits 16 and 18. Thereby, the update cycle of the Duty signal can be shortened. Moreover, even when a power supply system abnormality occurs, appropriate fail-safe operation such as suppressing a shortage of power supply to the in-vehicle load 32 or the like while suppressing a decrease in reliability of the power system can be performed. it can.

  According to the embodiment described in detail above, the following effects can be obtained.

  (1) Each of these control circuits 16 and 18 prevents each of the periods in which the switching elements are turned on by the duty signal output from each of the first control circuit 16 and the second control circuit 18 from overlapping each other. A duty signal was generated. According to such a configuration, the update cycle of the Duty signal can be shortened, and the switching frequency can be increased. Thereby, the responsiveness of the output voltage VL of the DCDC converter 12 can be improved, and the components (transformer 14, switching elements Sp1, Sn1, Sp2, Sn2, etc.) constituting the DCDC converter 12 can be reduced in size.

  Furthermore, since the responsiveness of the output voltage VL can be improved, it can be expected that the voltage change calculation unit B4, the correction amount calculation unit B5, and the addition unit B6 of FIG.

  Note that when the duty signal for the switching element is generated by a single control circuit, the duty signal update cycle may be shortened for reasons such as restrictions on the calculation speed of the control circuit and diversion of a conventional control circuit. It may be difficult to update the Duty signal over a plurality of switching periods (for example, five switching periods). Here, according to the improvement in the responsiveness of the output voltage VL described above, even if the required power of the equipment on the high voltage system side using the high voltage battery 10 as a power supply source fluctuates, this fluctuation is reflected in the output voltage VL. The influence exerted can be suppressed. Thereby, for example, fluctuations in the applied voltage of the in-vehicle load 32 (headlight) can be suppressed, and a situation in which the user feels uncomfortable due to flickering of the headlight can be avoided.

  (2) The input voltage VH, the input current IH, and the output voltage VL of the DCDC converter 12 are used as the abnormality determination parameter P, and correspond to the abnormality determination parameter P corresponding to the first control circuit 16 and the second control circuit 18. When it is determined that the absolute value of the difference between the abnormality determination parameters P is larger than the threshold value γ, it is determined that an abnormality has occurred in the power supply system. Thereby, the presence or absence of abnormality of a power supply system can be judged appropriately.

  (3) In a situation where it is determined that an abnormality has occurred in the power supply system, the duty signal having the shorter on-time Ton among the duty signals generated by the first control circuit 16 and the second control circuit 18 is turned on. The transmission of the duty signal having the longer on time Ton to the switching circuit 36 is cut off by doubling the time Ton. Thereby, even if an abnormality occurs in the power supply system, it is possible to avoid the occurrence of insufficient power supply to the in-vehicle load 32 and the like, and it is possible to prevent the low voltage battery 28 from rising. In addition, it is possible to suitably avoid a decrease in reliability of the power supply system caused by an excessively high output voltage of the DCDC converter 12.

(Second Embodiment)
Hereinafter, the second embodiment will be described with reference to the drawings with a focus on differences from the first embodiment.

  FIG. 5 shows the overall configuration of the power supply system according to the present embodiment. In the present embodiment, a logic circuit and a third control circuit (hereinafter, monitoring circuit 44) that transmit the duty signal output from the first and second control circuits 16 and 18 to the switching circuit 36 in the power supply system. The other configuration is basically the same as that of the first embodiment. Therefore, in FIG. 5, the logic circuit and the monitoring circuit 44 will be mainly described. Moreover, in this embodiment, the same code | symbol is attached | subjected for convenience about the member same as the member shown in FIG. 1 of previous 1st Embodiment.

  As illustrated, in the present embodiment, the DCDC converter 12 includes the monitoring circuit 44 in addition to the first control circuit 16 and the second control circuit 18.

  Similar to the first control circuit 16 and the second control circuit 18, the monitoring circuit 44 includes an AD conversion unit 44a, an arithmetic processing unit 44b, a timer circuit 44c, an output port 44d, and an interface 44e. Information of the first control circuit 16 and the second control circuit 18 is input to the monitoring circuit 44 via the interface 44e. The monitoring circuit 44 performs processes other than the output setting process in the above-described series of control processes of the DCDC converter 12. That is, the monitoring circuit 44 has a circuit configuration that cannot transmit the duty signal to the switching circuit 36.

  Further, the determination signal A and the determination signal B are output from the monitoring circuit 44. A signal obtained by logically inverting these determination signals A and B is input to the AND circuit 46.

  The output signal of the AND circuit 46 is input to the first control circuit 16 as a third determination signal. In addition to the output signal of the AND circuit 46, the second determination signal output from the first control circuit 16 and the first determination signal output from the second control circuit 18 are sent to the AND circuit 48. Entered. The output signal of the AND circuit 48 and the determination signal A are input to the OR circuit 50.

  The output signal of the OR circuit 50 is input to each of the AND circuits 38p1, 38n1, 38p2, and 38n2. A determination signal B is input to each of the AND circuits 40p1, 40n1, 40p2, and 40n2.

  Next, the abnormality determination process of the power supply system according to the present embodiment will be described.

  In this embodiment, the first control circuit 16, the second control circuit 18, and the monitoring circuit 44 determine whether an abnormality has occurred in the power supply system. Here, the abnormality determination process mainly composed of the first control circuit 16, the second control circuit 18, and the monitoring circuit 44 conforms to the procedure shown in FIG.

  Specifically, it is determined that an abnormality has occurred in the power supply system by an abnormality determination process between the first control circuit 16 and the second control circuit 18 and mainly performed by the first control circuit 16. In this case, the first control circuit 16 performs a process of inverting the logic of the second determination signal from “H” to “L” and doubling the on-time Ton calculated by the calculation process. On the other hand, it is determined that an abnormality has occurred in the power supply system by the abnormality determination process between the first control circuit 16 and the second control circuit 18 and mainly performed by the second control circuit 18. In this case, the second control circuit 18 performs a process of inverting the logic of the first determination signal from “H” to “L” and doubling the on-time Ton calculated by the calculation process.

  Further, when it is determined that an abnormality has occurred in the power supply system by the abnormality determination process between the first control circuit 16 and the monitoring circuit 44 and the abnormality determination process mainly performed by the monitoring circuit 44, the monitoring circuit 44 The logic of the determination signal A is inverted from “H” to “L”. On the other hand, when it is determined that an abnormality has occurred in the power supply system by the abnormality determination processing between the second control circuit 18 and the monitoring circuit 44 and the abnormality determination processing mainly performed by the monitoring circuit 44, the monitoring circuit 44 The logic of the determination signal B is inverted from “H” to “L”.

  Next, the fail safe regarding the operation of the switching element after the abnormality determination of the power supply system according to the present embodiment will be described.

  In this embodiment, when it is determined that an abnormality has occurred in the power supply system, the duty signals generated by the first control circuit 16, the second control circuit 18, and the monitoring circuit 44 are the same as each other. A process of turning on / off the switching element is performed by a Duty signal corresponding to the one having the largest number of on-times Ton.

  6 and 7 show an example of the abnormality determination process of the power supply system according to the present embodiment and the fail-safe process after the abnormality determination.

  First, FIG. 6 shows a case where an abnormality relating to the first control circuit 16 occurs as an abnormality of the power supply system. Specifically, FIG. 6 (a), FIG. 6 (b-1) to FIG. 6 (b-4), FIG. 6 (c-1) to FIG. 6 (c-4), and FIG. This corresponds to FIG. 4A, FIG. 4B-1 to FIG. 4B-4, FIG. 4C-1 to FIG. 4C-4, and FIG. FIG. 6B-5 shows the transition of the output state of the third determination signal from the first control circuit 16, and FIG. 6D-1 shows the transition of the counter value of the timer circuit 44c. 6 (d-2) shows the transition of the processing contents of the monitoring circuit 44, FIG. 6 (d-3) shows the transition of the Duty signal generated in the monitoring circuit 44, and FIG. 4) shows the transition of the output state of the judgment signal A from the monitoring circuit 44 (output port 44d), and FIG. 6 (d-5) shows the transition of the output state of the judgment signal B from the monitoring circuit 44.

  In the present embodiment, the monitoring circuit 44 is required to complete a series of control processing of the DCDC converter 12 within a predetermined processing cycle (half processing cycle of the first control circuit 16 or the second control circuit 18). Therefore, the monitoring circuit 44 executes a plurality of processes in parallel.

  In the illustrated example, the start timing of the series of control processes by the second control circuit 18 is later than the start timing of the series of control processes by the first control circuit 16, and The start timing of the control process is later than the start timing of a series of control processes by the second control circuit 18.

  Here, at times t2 to t3, based on the received AD conversion value of the first control circuit 16 and the AD conversion value of the monitoring circuit 44, it is determined that no abnormality has occurred in the power supply system in the monitoring circuit 44. The For this reason, the logic of the determination signal A is maintained at “H”, and the Duty signal generated by the first control circuit 16 by time t3 is transmitted to the switching circuit 36 in the processing cycle from time t3 to t5.

  At subsequent times t3 to t4, based on the received AD conversion value of the second control circuit 18 and the AD conversion value of the monitoring circuit 44, it is determined that no abnormality has occurred in the power supply system in the monitoring circuit 44. For this reason, the logic of the determination signal B is maintained at “H”, and the Duty signal generated by the second control circuit 18 at time t2 to t4 is transmitted to the switching circuit 36 at the processing period from time t4 to t6. .

  At subsequent times t4 to t5, a temporary abnormality occurs in the power supply system, so that the power supply in the monitoring circuit 44 is based on the received AD conversion value of the first control circuit 16 and the AD conversion value of the monitoring circuit 44. It is determined that an abnormality has occurred in the system. Thereby, at time t5, the logic of the determination signal A is inverted from “H” to “L”. Further, based on the AD conversion value of the first control circuit 16 and the received AD conversion value of the second control circuit 18, it is determined that an abnormality has occurred in the power supply system in the first control circuit 16. . Thereby, at time t5, the logic of the second determination signal is inverted from “H” to “L”, and the on-time Ton of the Duty signal is doubled. Further, at time t4 to t6, an abnormality occurs in the power supply system in the second control circuit 18 based on the AD conversion value of the second control circuit 18 and the received AD conversion value of the first control circuit 16. It is judged that it is. As a result, at time t6, the logic of the first determination signal is inverted to “L” and the on-time Ton of the Duty signal is doubled.

  That is, when it is determined in the abnormality determination process between the first control circuit 16 and the second control circuit 18 that an abnormality has occurred in the power supply system, as shown in FIG. 5, the first control circuit 16 And the logic of the first determination signal output from the second control circuit 18 is inverted to “L”, and the logic of the output signal of the AND circuit 48 is set to “L”. " Further, when it is determined by the abnormality determination process between the first control circuit 16 and the monitoring circuit 44 that an abnormality has occurred in the power supply system, the logic of the determination signal A output from the monitoring circuit 44 becomes “L”. Inverted. As a result, the logic of the output signal of the OR circuit 50 is set to “L”.

  Therefore, after time t6, which is the next processing cycle, transmission of the duty signal from the first control circuit 16 to the switching circuit 36 is interrupted, and the duty signal generated by the second control circuit 18 is switched to the switching circuit. 36. Here, the duty signals generated by the second control circuit 18 and the monitoring circuit 44 are the same among the duty signals generated by the first and second control circuits 16 and 18 and the monitoring circuit 44, respectively. This is a duty signal having the largest on-time Ton and a signal having a high probability of being normal.

  After that, at times t7 to t8, the first control circuit 16 has an abnormality in the power supply system based on the AD conversion value of the first control circuit 16 and the received AD conversion value of the second control circuit 18. Therefore, the logic of the second determination signal is inverted to “H” at time t8.

  Next, FIG. 7 shows a case where an abnormality relating to the monitoring circuit 44 occurs as an abnormality of the power supply system. Specifically, FIGS. 7A to 7E correspond to FIGS. 6A to 6E.

  In the illustrated example, after an operation signal is input from the vehicle ECU 30, monitoring is performed based on the received AD conversion value of the first control circuit 16 and the AD conversion value of the monitoring circuit 44 at times t 1 to t 2. In circuit 44, it is determined that an abnormality has occurred in the power supply system. Therefore, the logic of the determination signal A is inverted to “L” at time t2.

  Thereafter, at time t2 to t3, based on the received AD conversion value of the second control circuit 18 and the AD conversion value of the monitoring circuit 44, it is determined that an abnormality has occurred in the power supply system in the monitoring circuit 44. . For this reason, the logic of the determination signal B is inverted to “L” at time t2.

  That is, when it is determined in the abnormality determination process between the second control circuit 18 and the monitoring circuit 44 that an abnormality has occurred in the power supply system, the logic of the determination signal B output from the monitoring circuit 44 is inverted to “L”. Is done. Further, when it is determined in the abnormality determination process between the first control circuit 16 and the monitoring circuit 44 that an abnormality has occurred in the power supply system, the logic of the determination signal A output from the monitoring circuit 44 is inverted to “L”. Is done. As a result, the logic of the output signals of the AND circuits 46 and 48 is maintained at “H”, and the logic of the output signal of the OR circuit 50 is set to “H”.

  Therefore, the duty signal generated by the first control circuit 16 is transmitted to the switching circuit 36, and the transmission of the duty signal generated by the second control circuit 18 to the switching circuit 36 is blocked. Here, the duty signals generated by the first control circuit 16 and the second control circuit 18 are the duty signals generated by the first and second control circuits 16 and 18 and the monitoring circuit 44, respectively. Of these, the Duty signal has the largest on-time Ton and is a signal having a high probability of being normal.

  Then, after time t4 when it is determined by the first control circuit 16 that the logic of the output signal (third determination signal) of the AND circuit 46 is inverted from “L” to “H”, the first control circuit 16 A process is performed in which the on-time Ton of the Duty signal generated by 16 is doubled.

  Thus, in the present embodiment, the duty signal having the largest number of on-times Ton that are the same among the duty signals generated by each of the first control circuit 16, the second control circuit 18, and the monitoring circuit 44. The switching element was turned on / off by. According to such a configuration, it is possible to suitably avoid the occurrence of insufficient power supply to the in-vehicle load 32 and the like while suitably suppressing a decrease in reliability of the power supply system.

(Third embodiment)
Hereinafter, the third embodiment will be described with reference to the drawings with a focus on differences from the second embodiment.

  In the second embodiment, an abnormality has occurred in the power supply system due to the abnormality determination process between the first control circuit 16 and the monitoring circuit 44 and the abnormality determination process between the second control circuit 18 and the monitoring circuit 44. When the determination is made, the duty signal generated by the first control circuit 16 out of the first control circuit 16 and the second control circuit 18 is transmitted to the switching circuit 36. In the present embodiment, when it is determined that the abnormality has occurred, the ON time Ton of the Duty signal from both the first and second control circuits 16 and 18 is not doubled, and the control circuits 16 , 18, 18 continues to transmit the duty signal to the switching circuit 36.

  FIG. 8 shows the overall configuration of the power supply system according to the present embodiment. In the present embodiment, the same members as those shown in FIG. 1 of the first embodiment are denoted by the same reference numerals for the sake of convenience.

  The output signal of the AND circuit 48 is input to the OR circuit 50 as a fourth determination signal together with the determination signal A output from the output port 44d of the monitoring circuit 44. In the present embodiment, the output signal (third determination signal) of the AND circuit 46 is not input to the first control circuit 16.

  The determination signal B output from the output port 44 d of the monitoring circuit 44 and the fourth determination signal output from the AND circuit 48 are input to the OR circuit 52. The output signal of the OR circuit 52 is input to each of the AND circuits 40p1, 40n1, 40p2, and 40n2.

  Next, the abnormality determination process of the power supply system according to the present embodiment will be described with reference to FIG. Specifically, FIG. 9 shows a case where an abnormality relating to the monitoring circuit 44 occurs as an abnormality of the power supply system. FIG. 9 (e) shows the transition of the output state of the fourth determination signal from the AND circuit 48. FIG. 9 (a) to FIG. 9 (b-4), FIG. 9 (c-1) to FIG. 9 (d-5) and FIG. 9 (f) are the same as FIGS. 6 (a) to 6 (b-4), 6 (c-1) to 6 (d-5) and 6 (e). ).

  In the illustrated example, after an operation signal is input from the vehicle ECU 30, monitoring is performed based on the received AD conversion value of the first control circuit 16 and the AD conversion value of the monitoring circuit 44 at times t 1 to t 2. In circuit 44, it is determined that an abnormality has occurred in the power supply system. Therefore, the logic of the determination signal A is inverted to “L” at time t2.

  At subsequent times t2 to t3, based on the received AD conversion value of the second control circuit 18 and the AD conversion value of the monitoring circuit 44, it is determined that an abnormality has occurred in the power supply system in the monitoring circuit 44. For this reason, the logic of the determination signal B is inverted to “L” at time t3. Accordingly, the logic of the fourth determination signal output from the AND circuit 48 is inverted from “L” to “H”, so that the logic of the output signals of the OR circuits 50 and 52 is maintained at “H”. . As a result, transmission of the duty signal from the first and second control circuits 16 and 18 to the switching circuit 36 is continued. As described above, the process of doubling the on-time Ton of the Duty signal generated by the first control circuit 16 and the second control circuit 18 is not performed.

(Other embodiments)
Each of the above embodiments may be modified as follows.

  The abnormality determination parameter P used for the abnormality determination process of the power supply system is not limited to all of the AD conversion values of the input voltage VH, the input current IH, and the output voltage VL. For example, one or two of these values may be used. It may be used. Moreover, as the abnormality determination parameter P, the on-time Ton of the Duty signal may be used in addition to or instead of the AD conversion value. The abnormality determination method in this case will be described. Specifically, for example, the most recent past AD conversion value of one of the first control circuit 16 and the second control circuit 18 is transmitted to the other. Then, in the other control circuit that has received the most recent AD conversion value, the absolute value of the difference between the on-time Ton calculated from the received AD conversion value and the on-time Ton calculated from its own AD conversion value is If it is determined that the value is greater than the predetermined threshold, it is determined that an abnormality has occurred in the power supply system.

  By the way, the predetermined threshold setting method will be described. The on-time is based on the AD conversion value including the deviation (sampling error) from the true values of the input voltage VH, the input current IH, and the output voltage VL due to the AD conversion processing. Ton can be calculated. For this reason, the predetermined threshold value corresponding to the on time Ton may be set based on, for example, the fluctuation range of the on time Ton corresponding to the fluctuation range of the AD conversion value due to the sampling error.

  In the second embodiment, an abnormality occurs in the power supply system between the abnormality determination process between the first control circuit 16 and the monitoring circuit 44 and the abnormality determination process between the second control circuit 18 and the monitoring circuit 44. If it is determined that the duty signal of the first control circuit 16 is transmitted to the switching circuit 36, the present invention is not limited to this. For example, instead of the first control circuit 16, the duty signal of the second control circuit 18 may be transmitted to the switching circuit 36.

  In the first embodiment, the process of doubling the on-time Ton of the Duty signal is performed in a situation where it is determined that an abnormality occurs in the power supply system, but the present invention is not limited to this. For example, the ON time Ton may be β times larger than 1 (for example, 1 <β <2). Even in this case, the supply power to the in-vehicle load 32 and the like is not increased while the expected decrease in the supply power of the DCDC converter 12 due to the transmission of the Duty signal to the switching circuit 36 being blocked. The degree of deficiency can be suppressed.

  In each of the above embodiments, one DCDC converter is provided in the power supply system. However, the present invention is not limited thereto, and a parallel connection body of a plurality of DCDC converters may be provided. Such a configuration is intended to increase the maximum value of the current supplied to the in-vehicle load 32 or the like. In such a power supply system, there is a concern that inconveniences such as failure to properly supply power to the power supply destination of the power supply system due to any abnormality in the DCDC converter may occur. For example, when the output current of one of the plurality of DCDC converters is low, the output voltage may be lowered if the maximum current value that can be supplied by the remaining DCDC converters is small. For this reason, even in such a power supply system, application of abnormality determination processing of the power supply system is effective.

  The number of control circuits provided in one DCDC converter is not limited to two or three, but may be four or more. Here, when three control circuits having a configuration capable of transmitting the duty signal to the switching circuit 36 are provided, each of these control circuits turns on the switching element corresponding to the duty signal output from each of these control circuits. The duty signal is generated so that the periods to be in a state do not overlap each other.

  In such a configuration, when it is determined in the first embodiment that an abnormality occurs in the power supply system, for example, the duty time with the shortest on time Ton among the duty signals generated by each of the four control circuits. Fail-safe may be performed by operating the switching element with a Duty signal in which the on-time Ton of the signal is tripled and the on-time Ton is tripled.

  In the first embodiment, the first control circuit 16 and the second control circuit 18 are configured to receive the detection value of the common input side voltage sensor 22 and the like. However, the present invention is not limited to this. For example, an input side voltage sensor or the like corresponding to each of the first control circuit 16 and the second control circuit 18 is provided separately, and abnormality determination is performed using detection values of the sensors corresponding to the control circuits 16 and 18, respectively. Processing may be performed.

  In each of the above embodiments, the abnormality determination process is performed by the control circuit included in the DCDC converter 12. However, the present invention is not limited to this. For example, a means (signal line) for exchanging information between the control circuit and the vehicle ECU 30 may be provided, and an abnormality determination process may be performed by the vehicle ECU 30 by inputting an AD conversion value or the like of the control circuit.

  In each of the above embodiments, the abnormality determination process is performed using the detection value of a sensor (such as the output-side voltage sensor 26) provided in the DCDC converter 12, but the present invention is not limited to this. For example, a sensor that detects the output voltage or output current of the DCDC converter 12 may be provided inside the power supply system and outside the DCDC converter 12, and the abnormality determination process may be performed based on the detection value of the sensor.

  The switching element included in the DCDC converter is not limited to those exemplified in the above embodiments, and may be, for example, a bipolar transistor or an IGBT.

  The DCDC converter is not limited to a step-down converter, and may be a step-up converter. Further, the power conversion device is not limited to an insulation type, and may be a non-insulation type.

  The vehicle to which the present invention is applied is not limited to a hybrid vehicle, and may be, for example, an electric vehicle including only a rotating machine as an in-vehicle main unit. The application object of the present invention is not limited to a vehicle.

DESCRIPTION OF SYMBOLS 10 ... High voltage battery, 12 ... DCDC converter, 16 ... 1st control circuit, 18 ... 2nd control circuit, 22 ... Input side voltage sensor, 24 ... Input side current sensor, 26 ... Output side voltage sensor, Sp1, Sn1 , Sp2, Sn2... Switching elements.

Claims (7)

A control circuit that generates a ratio signal that defines a ratio of an on-time to an on-state and an off-state of the switching element, and that is output by an on / off operation of the switching element based on the generated time-ratio signal; In a power supply system including a DCDC converter whose voltage is controlled,
A plurality of the control circuits are provided in one DCDC converter,
Each of the plurality of control circuits generates the time ratio signal based on the time ratio signal output from each of the control circuits so that the periods during which the switching elements are turned on do not overlap each other. And power system. Further comprising a detecting means for detecting a voltage or current of a current flow path of the power supply system,
Each of the plurality of control circuits generates the duty ratio signal with the detection value of the detection means as an input,
The power supply based on at least one of comparison between detection values of the detection means input to each of the plurality of control circuits and comparison between the time ratio signals generated by each of the plurality of control circuits. The power supply system according to claim 1, further comprising abnormality determination means for determining whether an abnormality has occurred in the system. When it is determined by the abnormality determining means that an abnormality has occurred in the power supply system, a time ratio signal that minimizes the ON time is selected from the time ratio signals generated by each of the plurality of control circuits. A selection means;
An on-time extension means for extending the on-time of the time ratio signal selected by the selection means;
3. The power supply system according to claim 2, further comprising an abnormality time operation means for turning on and off the switching element by a time ratio signal in which the on time is extended by the on time extension means. Three or more control circuits are provided in one DCDC converter,
When it is determined by the abnormality determining means that an abnormality has occurred in the power supply system, the number of ON times that are the same among the time ratio signals generated by each of the three or more control circuits is the largest. A selection means for selecting a large ratio signal;
An on-time extension means for extending the on-time of the time ratio signal selected by the selection means;
3. The power supply system according to claim 2, further comprising: an abnormal time majority operation means for turning on and off the switching element by a time ratio signal in which the on time is lengthened by the on time extension means. And at least two of the three or more control circuits are capable of transmitting the time ratio signal to the switching element, and the remainder is not capable of transmitting the time ratio signal to the switching element,
When it is determined by the abnormality determining means that an abnormality has occurred only in the control circuit that cannot transmit the time ratio signal to the switching element among the three or more control circuits, the on-time extending means determines the time And further comprising a continuation operation means for continuing the transmission of the time ratio signal from each of the control circuits capable of transmitting the time ratio signal to the switching element without increasing the ON time of the ratio signal. The power supply system according to claim 4. A signal blocking means for blocking transmission of the time ratio signal from a control circuit other than the control circuit that generates the time ratio signal selected by the selection means among the plurality of control circuits;
The on-time extension means lengthens the on-time so as to compensate for the power supplied to the DCDC converter, which is assumed to be lowered by the transmission of the time ratio signal being cut off by the signal cut-off means. The power supply system according to any one of claims 3 to 5. The power supply system is mounted on a vehicle,
7. The vehicle according to claim 1, wherein the vehicle includes a high-voltage side vehicle-mounted load and a high-voltage battery serving as a power supply source for the high-voltage side vehicle-mounted load and the DCDC converter. Power system.

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