JP2008125156A - Voltage converter and driving system equipped with same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a voltage converter capable of correctly determining the generation of a leak current and a driving system equipped with the same, in a semiconductor switching element for controlling precharge of a capacitor provided on an input side of a driving circuit. <P>SOLUTION: In a DC-DC converter 30, an MOS transistor 35 and a resistor 36 are connected in series, and connected to a negative bus bar 14 in parallel to a system main relay SMR2. An ECU 40 determines whether or not a leak current is generated in the MOS transistor 35 on the basis of a current Ir flowing through the resistor 36 detected using a current sensor 38. The ECU 40 varies a reference current used for determining whether or not the leak current has been generated on the basis of the degree of dew condensation of the DC-DC converter 30 detected by a dew condensation sensor 39. When the MOS transistor 35 determines that the leak current has not been generated, the ECU 40 precharges a capacitor 22. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a voltage conversion device and a drive system including the same, and more particularly to a voltage conversion device including means for determining the occurrence of leakage current in a semiconductor switching element included in the voltage conversion device and a drive system including the voltage conversion device. .

  Japanese Patent Laying-Open No. 2005-253206 (Patent Document 1) discloses a voltage conversion device that controls precharge of a capacitor provided on the input side of a motor generator drive circuit.

  According to this, the semiconductor switching element and the drive circuit for controlling the precharge of the capacitor are provided in the voltage converter. Thus, by configuring the voltage converter so that the precharge of the capacitor can be controlled, it is not necessary to separately secure a space for arranging the semiconductor switching element and the drive circuit, and the drive system including the voltage converter is provided. We are trying to make it more compact.

And the voltage converter by patent document 1 has the leak determination means which determines whether the leakage current has generate | occur | produced in the semiconductor switching element, and when the leakage current has not generate | occur | produced in the semiconductor switching element, Control to precharge the capacitor.
JP-A-2005-253206 JP-A-5-260764 JP 2000-16714 A JP 2001-251078 A Japan Society for Invention and Innovation Public Technical Bulletin No. 2006-500835

  According to the voltage conversion device disclosed in Japanese Patent Laid-Open No. 2005-253206, the leak determination means detects the voltage across the resistor connected in series with the semiconductor switching element by the voltage sensor, and the detected voltage and the predetermined voltage are detected. Whether or not a leakage current is generated in the semiconductor switching element is determined based on the result of comparison with the reference value.

  However, in the method for determining the occurrence of leakage current in the semiconductor switching element based on the detection value of the voltage sensor, the detection value of the voltage sensor exceeds the reference value even for the current generated due to a factor different from the leakage current. For this reason, there is a problem that it is determined that a leak current is generated.

  For example, when condensation occurs in the voltage converter, there is a possibility that it is erroneously determined that a leakage current is generated in the semiconductor switching element based on a current generated by a leakage path formed in the semiconductor switching element. There is. In such a case, since it is determined that the drive system is abnormal due to an erroneous determination by the leak determination means, it is impossible to accurately control the capacitor precharge.

  Therefore, the present invention has been made to solve such a problem, and an object of the present invention is to generate a leakage current in a semiconductor switching element for controlling precharge of a capacitor provided on the input side of a drive circuit. It is an object to provide a voltage converter that can accurately determine the above.

  Another object of the present invention is to provide a drive system including a voltage converter that accurately controls the precharge of a capacitor provided on the input side of the drive circuit.

  According to the present invention, the voltage converter is a voltage converter that receives a DC voltage from a power supply that supplies power to a load drive circuit and converts the voltage level of the received DC voltage. The voltage conversion device includes a voltage converter for converting a voltage level of a DC voltage received from a power supply, and a first bus and a second bus connected to a positive bus and a negative bus between the power supply and a capacitor included in the drive circuit, respectively. A semiconductor switching element connected in parallel with any one of the relays, and between the power source and the capacitor, connected in parallel with one relay, and a resistor connected in series with the semiconductor switching element, A current sensor that detects a current flowing through a resistor and outputs a current detection value, and a leak determination unit that determines whether or not a leak current is generated in the semiconductor switching element by comparing the current detection value with a determination reference value And a dew condensation sensor for detecting the degree of dew condensation in the voltage converter. The leak determination unit includes a determination reference value setting unit that makes the determination reference value variable in accordance with the degree of condensation detected by the dew condensation sensor.

  According to the above voltage converter, a leak current is generated in the semiconductor switching element based on the current generated due to the condensation by setting the determination reference value according to the degree of the condensation generated in the device. It can be prevented from being erroneously determined to be present. As a result, it is possible to accurately determine the occurrence of a leakage current in the semiconductor switching element, so that the capacitor can be accurately precharged.

  Preferably, the determination reference value includes a determination reference current for comparing the magnitude with the detected current value. The determination reference value setting means sets the determination reference current so that the determination reference current increases as the degree of condensation detected by the dew condensation sensor increases. The leak determination unit determines that a leak current is generated in the semiconductor switching element when the detected current value exceeds the determination reference current set by the determination reference value setting unit.

  According to the above voltage converter, by setting the determination reference current according to the degree of condensation that has occurred in the device, the current generated due to condensation exceeds the determination reference current. It is possible to prevent erroneous determination that a leakage current is generated in the switching element.

  Preferably, the determination reference value includes a determination reference time for comparing a period in which a state exceeding a predetermined determination reference current continues with a current detection value. The determination reference value setting means sets the determination reference time so that the determination reference time becomes longer as the degree of condensation detected by the dew condensation sensor increases. The leakage determination means determines that the leakage current is detected when it is determined that the state where the current detection value exceeds the predetermined determination reference current continues beyond the determination reference period set by the determination reference value setting means. It is determined that it has occurred.

  According to the voltage conversion device described above, by setting the determination reference time according to the degree of condensation occurring in the device, the state where the current generated due to condensation exceeds the determination reference current is determined as the determination reference time. It is possible to prevent erroneous determination that a leakage current is generated in the semiconductor switching element based on the fact that it continues beyond.

  Further, according to the present invention, the voltage converter is a voltage converter that receives a DC voltage from a power supply that supplies power to a load drive circuit and converts the voltage level of the received DC voltage. The voltage converter includes a voltage converter that converts a voltage level of a DC voltage received from a power source, and a first bus and a second relay that are respectively connected to a positive bus and a negative bus between the power source and a drive circuit. A semiconductor switching element connected in parallel with one of the relays, and a resistor connected in parallel with the one relay and connected in series with the semiconductor switching element between the power source and the drive circuit, and flow through the resistance A current sensor that detects a current and outputs a current detection value; a dew condensation determination unit that determines whether or not dew condensation has occurred in the voltage conversion device; and that no dew condensation has occurred in the voltage conversion device by the dew condensation determination unit Leak determination means for determining whether or not a leakage current is generated in the semiconductor switching element based on the detected current value when determined.

  According to the above voltage conversion device, since it is determined whether or not a leakage current is generated in the semiconductor switching element in a state where no condensation occurs in the device, based on the current generated due to the condensation, It is possible to prevent erroneous determination that a leakage current is generated in the semiconductor switching element. As a result, it is possible to accurately determine the occurrence of a leakage current in the semiconductor switching element, so that the capacitor can be accurately precharged.

  Preferably, the voltage conversion device further includes a temperature raising unit configured to raise the temperature of the voltage conversion device when it is determined by the condensation determination unit that condensation has occurred in the voltage conversion device.

  According to the voltage converter described above, since it is determined whether or not the leakage current is generated in the semiconductor switching element in a state where condensation in the apparatus is reliably eliminated, the generation of the leakage current in the semiconductor switching element is accurately determined. Can be determined.

  Preferably, the temperature raising unit performs drive control of the voltage converter when it is determined by the condensation determination unit that condensation has occurred in the voltage converter.

  According to the voltage conversion device, it is possible to easily eliminate condensation in the device by driving the voltage converter included in the device.

  Preferably, the voltage conversion device further includes a blower mechanism configured to blow air to the voltage conversion device. The temperature raising means controls the air blowing mechanism so that air is blown to the voltage conversion apparatus when it is determined by the condensation determination means that condensation has occurred in the voltage conversion apparatus.

  According to the voltage conversion device, it is possible to easily eliminate dew condensation in the device by driving the air blowing mechanism included in the device.

  Preferably, the voltage conversion device further includes a drive circuit for turning on / off the semiconductor switching element. In response to determining that no leakage current is generated in the semiconductor switching element when the other relay of the first and second relays is closed when starting the load, the drive circuit When the capacitor voltage reaches a predetermined voltage, the semiconductor switching element is turned off.

  According to the voltage converter described above, it is possible to accurately determine the occurrence of a leakage current in the semiconductor switching element, so that the capacitor can be precharged accurately.

  According to the invention, the drive system includes a power source, a motor drive device that drives the motor generator by the first DC voltage received from the power source, and a positive bus and a negative bus that connect the power source and the motor drive device. And a voltage converter connected in parallel to the motor driving device and converting the first DC voltage received from the power source into the second DC voltage. The motor drive device includes a capacitor on the power supply side, and is connected between the drive circuit for driving the motor generator by converting the first DC voltage into an AC voltage, and the positive bus and the negative bus between the power supply and the capacitor. First and second relays. A voltage converter includes a voltage converter that converts a first DC voltage into a second DC voltage, a semiconductor switching element that is connected in parallel with one of the first and second relays, a power source, A resistor connected in parallel with one of the relays and connected in series with the semiconductor switching element, a current sensor that detects a current flowing through the resistor and outputs a current detection value, and a current detection value Is compared with a determination reference value, thereby including a leak determination means for determining whether or not a leak current is generated in the semiconductor switching element, and a dew condensation sensor for detecting the degree of dew condensation in the voltage converter. The leak determination unit includes a determination reference value setting unit that makes the determination reference value variable in accordance with the degree of condensation detected by the dew condensation sensor.

  According to the drive system described above, by setting a determination reference value according to the degree of condensation that has occurred in the voltage converter, the semiconductor switching element included in the voltage converter can be used based on the current that has occurred due to condensation. It is possible to prevent erroneous determination that a leakage current is generated. As a result, the capacitor provided on the input side of the motor drive circuit can be accurately precharged.

  Preferably, the determination reference value includes a determination reference current for comparing the magnitude with the detected current value. The determination reference value setting means sets the determination reference current so that the determination reference current increases as the degree of condensation detected by the dew condensation sensor increases. The leak determination unit determines that a leak current is generated in the semiconductor switching element when the detected current value exceeds the determination reference current set by the determination reference value setting unit.

  According to the above drive system, by setting the determination reference current according to the degree of condensation generated in the voltage converter, the current generated due to condensation exceeds the determination reference current, It is possible to prevent erroneous determination that a leakage current is generated in the semiconductor switching element included in the voltage conversion device.

  Preferably, the determination reference value includes a determination reference time for comparing a period in which a state exceeding a predetermined determination reference current continues with a current detection value. The determination reference value setting means sets the determination reference time so that the determination reference time becomes longer as the degree of condensation detected by the dew condensation sensor increases. The leakage determination means determines that the leakage current is detected when it is determined that the state where the current detection value exceeds the predetermined determination reference current continues beyond the determination reference period set by the determination reference value setting means. It is determined that it has occurred.

  According to the drive system described above, the determination reference time is set according to the degree of condensation that has occurred in the voltage converter, so that the state in which the current generated due to condensation exceeds the determination reference current is determined by the determination reference time. Therefore, it is possible to prevent erroneous determination that a leakage current is generated in the semiconductor switching element included in the voltage conversion device based on the fact that the voltage exceeds the threshold value.

  According to the invention, the drive system includes a power source, a motor drive device that drives the motor generator by the first DC voltage received from the power source, and a positive bus and a negative bus that connect the power source and the motor drive device. And a voltage converter connected in parallel to the motor driving device and converting the first DC voltage received from the power source into the second DC voltage. The motor drive device includes a capacitor on the power supply side, and is connected between the drive circuit for driving the motor generator by converting the first DC voltage into an AC voltage, and the positive bus and the negative bus between the power supply and the capacitor. First and second relays. A voltage converter includes a voltage converter that converts a first DC voltage into a second DC voltage, a semiconductor switching element that is connected in parallel with one of the first and second relays, a power source, A resistor connected in parallel with one of the relays and connected in series with the semiconductor switching element, a current sensor that detects a current flowing through the resistor and outputs a current detection value, and a voltage converter A condensation determining means for determining whether or not condensation has occurred in the semiconductor switching element, and when the condensation determining means determines that no condensation has occurred in the voltage converter, a leak occurs in the semiconductor switching element based on the detected current value. Leakage determining means for determining whether or not current is generated.

  According to the above drive system, it is determined whether or not a leakage current is generated in the semiconductor switching element included in the voltage conversion device in a state where no condensation occurs in the voltage conversion device. It is possible to prevent erroneous determination that a leakage current is generated in the semiconductor switching element based on the current. As a result, the capacitor provided on the input side of the motor drive circuit can be accurately precharged.

  Preferably, the voltage conversion device further includes a temperature raising unit configured to raise the temperature of the voltage conversion device when it is determined by the condensation determination unit that condensation has occurred in the voltage conversion device.

  According to the drive system described above, since it is determined whether or not a leakage current is generated in the semiconductor switching element included in the voltage conversion device in a state where the dew condensation in the voltage conversion device is reliably eliminated, The occurrence of leak current can be accurately determined.

  Preferably, the temperature raising unit performs drive control of the voltage converter when it is determined by the condensation determination unit that condensation has occurred in the voltage converter.

  According to the above drive system, it is possible to easily eliminate dew condensation of the device by driving the voltage converter included in the voltage converter.

  Preferably, the voltage conversion device further includes a blower mechanism configured to blow air to the voltage conversion device. The temperature raising means controls the air blowing mechanism so that air is blown to the voltage conversion apparatus when it is determined by the condensation determination means that condensation has occurred in the voltage conversion apparatus.

  According to the above drive system, it is possible to easily eliminate dew condensation of the device by driving the blower mechanism included in the voltage conversion device.

  Preferably, the voltage conversion device further includes a drive circuit for turning on / off the semiconductor switching element. In response to determining that no leakage current is generated in the semiconductor switching element when the other relay of the first and second relays is closed when starting the load, the drive circuit When the capacitor voltage reaches a predetermined voltage, the semiconductor switching element is turned off.

  According to the above drive system, it is possible to accurately determine the occurrence of a leakage current in the semiconductor switching element, so that it is possible to accurately precharge a capacitor provided on the input side of the motor drive circuit.

  According to the present invention, it is possible to accurately determine the occurrence of a leakage current in a semiconductor switching element provided in the voltage converter for controlling the precharge of a capacitor provided on the input side of the drive circuit. As a result, according to the present invention, the capacitor can be accurately precharged.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same reference numerals indicate the same or corresponding parts.

[Embodiment 1]
FIG. 1 is a schematic block diagram of a drive system according to Embodiment 1 of the present invention.

  Referring to FIG. 1, a drive system 100 includes a battery 10, system main relays SMR1 and SMR2, a positive bus 13, a negative bus 14, a voltage sensor 15, a current sensor 16, and an IPM (Intelligent Power Module). 20, a DC / DC converter 30, and an ECU (Electronic Control Unit) 40.

  Motor generator MG is a motor for driving drive wheels of a hybrid vehicle or an electric vehicle. Motor generator MG may be a motor that is connected to an engine of a hybrid vehicle and functions as a generator that generates electric power by the rotational force of the engine or an electric motor that can start the engine.

  IPM 20 includes an inverter 21 and a capacitor 22. The DC / DC converter 30 includes an internal power supply 31, a control circuit 32, a voltage converter 33, a diode 34, a MOS transistor 35, a resistor 36, and a drive circuit 37.

  System main relay SMR 1 is connected in positive bus 13, and system main relay SMR 2 is connected in negative bus 14. Positive bus 13 has one end connected to the positive electrode of battery 10 and the other end connected to inverter 21 of IPM 20. Negative bus 14 has one end connected to the negative electrode of battery 10 and the other end connected to inverter 21 of IPM 20.

  Capacitor 22 is provided on the input side of inverter 21 and is connected between positive bus 13 and negative bus 14.

  In DC / DC converter 30, MOS transistor 35 and resistor 36 are connected in series, and MOS transistor 35 and resistor 36 connected in series are connected to negative bus 14 in parallel with system main relay SMR2. Current sensor 38 detects current Ir flowing through resistor 36 and outputs the detected current Ir to ECU 40.

  Note that the MOS transistor 35 and the resistor 36 connected in series may be connected in parallel to the system main relay SMR1. That is, the MOS transistor 35 and the resistor 36 connected in series only need to be connected in parallel with one of the system main relays SMR1 and SMR2.

The diode 34 is connected to the MOS transistor 35 in antiparallel.
The battery 10 includes a secondary battery such as lithium ion or nickel metal hydride. System main relays SMR1 and SMR2 are turned on / off by signals SE1 and SE2 from ECU 40, respectively. More specifically, the system main relay SMR1 is turned on (conducted) by an H (logic high) level signal SE1 from the ECU 40, and is turned off (non-conducted) by an L (logic low) level signal SE1 from the ECU 40. The System main relay SMR2 is turned on (conductive) by H-level signal SE2 from ECU 40, and is turned off (non-conductive) by L-level signal SE2 from ECU 40.

  Voltage sensor 15 detects voltage Vc across capacitor 22 and outputs the detected voltage Vc to ECU 40. Current sensor 16 detects motor current MCRT flowing through each phase coil of motor generator MG, and outputs the detected motor current MCRT to ECU 40.

  The capacitor 22 smoothes the DC voltage supplied from the battery 10 and supplies it to the inverter 21. Inverter 21 converts the DC voltage supplied from capacitor 22 into an AC voltage by signal PWM from ECU 40 to drive motor generator MG.

  The internal power supply 31 supplies power to the control circuit 32 and the drive circuit 37. The control circuit 32 is driven by the power from the internal power supply 31 and controls the voltage converter 33. The voltage converter 33 is connected to a node N1 between the battery 10 and the system main relay SMR1, and a node N2 between the node N2 between the battery 10 and the system main relay SMR2. Receive. Voltage converter 33 converts the DC voltage received from battery 10 in accordance with control from control circuit 32, and supplies the converted DC voltage to a load such as an auxiliary battery (not shown).

  The diode 34 suppresses current from flowing from the resistor 36 side to the node N2 side. The MOS transistor 35 is turned on / off by a signal VG1 from the drive circuit 37. Specifically, the MOS transistor 35 is turned on by the H level signal VG1 from the drive circuit 37 and turned off by the L level signal VG1.

  When the drive circuit 37 receives an H level signal DRV from the ECU 40, the drive circuit 37 generates an H level signal VG1 and outputs it to the gate terminal of the MOS transistor 35. When the drive circuit 37 receives an L level signal DRV from the EUC 40, the drive circuit 37 VG1 is generated and output to the gate terminal of the MOS transistor 35. That is, the drive circuit 37 turns the MOS transistor 35 on / off.

  In the embodiment of the present invention, battery 10, system main relays SMR 1 and SMR 2, and DC / DC converter 30 are housed in battery pack 50. A diode 34, a MOS transistor 35, a resistor 36, and a drive circuit 37 for controlling the precharge of the capacitor 22 when the motor generator MG is started are arranged in the DC / DC converter 30.

  With such a configuration, it is not necessary to separately secure a space for mounting the diode 34, the MOS transistor 35, the resistor 36, and the drive circuit 37, and the drive system 100 can be made compact.

  Further, since the drive circuit 37 uses the internal power supply 31 of the DC / DC converter 30 as a drive power supply circuit, there is no need to provide a separate drive circuit 37 drive power circuit, and the drive system 100 can be made compact and low in cost. Can be realized.

  Furthermore, it is not necessary to separately provide a substrate and a housing for the diode 34, the MOS transistor 35, the resistor 36, and the drive circuit 37, and the drive system 100 can be reduced in cost.

  ECU 40 receives signal IG from an ignition key (not shown). The signal IG becomes H level when the ignition key is turned on, and becomes L level when the ignition key is turned off. Further, ECU 40 receives voltage Vc from voltage sensor 15, receives motor current MCRT from current sensor 16, and receives torque command value TR from an ECU provided outside drive system 100.

  When the ECU 40 receives the H level signal IG from the ignition key, the ECU 40 generates an H level signal DRV, an H level signal SE1 and an L level signal SE2, and generates the generated H level signal DRV. The generated H level signal SE1 is output to the system main relay SMR1, and the generated L level signal SE2 is output to the system main relay SMR2.

  Thereafter, the ECU 40 compares the voltage Vc with a predetermined precharge voltage. When the voltage Vc reaches the predetermined precharge voltage, the ECU 40 generates an L level signal DRV and an H level signal SE2, and generates the generated L level signal. The signal DRV is output to the drive circuit 37, and the generated H level signal SE2 is output to the system main relay SMR2.

  Further, ECU 40 generates a signal PWM for driving inverter 21 based on torque command value TR, voltage Vc and motor current MCRT, and outputs the generated signal PWM to inverter 21.

  Further, the ECU 40 determines whether or not a leak current is generated in the MOS transistor 35 based on the current Ir received from the current sensor 38. When it is determined that no leak current is generated in MOS transistor 35, ECU 40 controls system main relay SMR1 and drive circuit 37 to precharge capacitor 22, and leaks current to MOS transistor 35. When it is determined that the error has occurred, a signal EMG for displaying “abnormal” is generated and output to the display means 60. The display means 60 displays “abnormal” in response to the signal EMG.

  FIG. 2 is a timing chart of operations of system main relays SMR1, SMR2 and MOS transistor 35 shown in FIG.

  Referring to FIG. 2, upon receiving an H level signal IG from the ignition key at timing t1, ECU 40 generates H level signal SE1, L level signal SE2, and L level signal DRV at timing t2. The generated H level signal SE1, L level signal SE2 and L level signal DRV are output to system main relay SMR1, system main relay SMR2 and drive circuit 37, respectively.

  The system main relay SMR1 is turned on in response to the H level signal SE1, and the system main relay SMR2 is turned off in response to the L level signal SE2. Further, the drive circuit 37 generates an L level signal VG1 in response to the L level signal DRV, outputs the signal VG1 to the gate terminal of the MOS transistor 35, and keeps the MOS transistor 35 off.

  Thereafter, the current sensor 38 detects the current Ir flowing through the resistor 36 and outputs it to the ECU 40. The ECU 40 compares the current Ir received from the current sensor 38 with the determination reference current Iref. At this time, as indicated by the curve k2, the ECU 40 determines that a leak current is generated in the MOS transistor 35 when the current Ir is higher than the determination reference current Iref, generates a signal EMG, and displays the display means 60. Output to. Then, the display unit 60 displays “abnormal” in accordance with the signal EMG.

  On the other hand, the ECU 40 determines that no leakage current is generated in the MOS transistor 35 when the current Ir is equal to or less than the determination reference current Iref as indicated by the straight line k1.

  Then, ECU 40 controls system main relays SMR1, SMR2 and drive circuit 37 to precharge capacitor 22 when it is determined that no leak current is generated in MOS transistor 35.

  Specifically, the ECU 40 generates an H level signal DRV at the timing t3 and outputs it to the drive circuit 37, and generates an L level signal DRV at the timing t5 and outputs it to the drive circuit 37. In addition, ECU 40 generates H-level signal SE2 at timing t4 and outputs it to system main relay SMR2.

  Then, during the period from timing t3 to timing t4, system main relay SMR1 and MOS transistor 35 are conductive, and system main relay SMR2 is nonconductive. Therefore, the DC current from battery 10 is the system main relay. The capacitor 22 is precharged through a closed circuit of the SMR 1, the capacitor 22, the resistor 36, the MOS transistor 35 and the battery 10. Therefore, the period from timing t3 to timing t4 is a period during which the capacitor 22 is precharged.

  When system main relay SMR2 is turned on at timing t4 and MOS transistor 35 is turned off at timing t5, battery 10 supplies a DC voltage to capacitor 22 via system main relays SMR1 and SMR2.

  As described above, according to the present embodiment, it is determined whether or not a leak current is generated in the MOS transistor 35 before the capacitor 22 is precharged. When the leak current is generated, an abnormality is displayed. The capacitor 22 is precharged when no leak current is generated. The purpose is to accurately control the precharge of the capacitor 22.

  However, according to this configuration, there is a possibility that it is erroneously determined that a leak current is generated in the MOS transistor 35 when the inside of the battery pack 50 is in an environment where condensation is likely to occur. As a result, although no leak current is generated in the MOS transistor 35, the precharge of the capacitor 22, the driving of the motor generator MG, and the voltage conversion in the voltage converter 33 are forcibly stopped.

  That is, when the ambient temperature in the battery pack 50 is low or the humidity is high, condensation may occur in the DC / DC converter 30. When dew condensation occurs in the MOS transistor 35 included in the DC / DC converter 30, the insulation resistance between the electrodes decreases and a leakage path is formed. Therefore, a current also flows in the resistor 36 connected in series with the MOS transistor 35. Ir flows. When the ECU 40 receives the current Ir flowing through the resistor 36 from the current sensor 38, the ECU 40 compares the current Ir with a predetermined determination reference current Iref. When the current Ir is higher than the predetermined determination reference current Iref, the ECU 40 leaks. It is determined that current is generated.

  However, in many cases, the dew condensation that has occurred in the MOS transistor 35 is eliminated soon after the MOS transistor 35 is energized and self-heats. Therefore, as in the case of a leak current generated due to a defective element structure, It is determined that there is a very low possibility that the operation of the drive system 100 will be hindered.

  Nevertheless, since it is determined that the leak current is uniformly generated based on the comparison result between the current Ir and the determination reference current Iref, it is intended that the precharge of the capacitor 22 is accurately controlled. The problem of going backward occurs.

  Therefore, the drive system 100 according to the present embodiment is configured such that the determination reference current Iref for determining whether or not a leak current is generated in the MOS transistor 35 is variable according to the degree of condensation of the DC / DC converter 30. . According to this, compared with a determination method in which the determination reference current Iref is set to a fixed value set in advance, it is possible to prevent erroneous determination of a current caused by condensation as a leakage current. it can. As a result, the precharge of the capacitor 22 can be controlled more accurately.

  Specifically, referring to FIG. 1 again, the DC / DC converter 30 is provided with a dew condensation sensor 39 for detecting the degree of dew condensation of the DC / DC converter 30. The condensation sensor 39 detects the degree of condensation of the DC / DC converter 30 by the following method, and outputs a signal Vd indicating the detected degree of condensation to the ECU 40.

FIG. 3 is a circuit diagram of the dew condensation sensor 39 in FIG.
Referring to FIG. 3, dew condensation sensor 39 includes resistors 80 and 82, a pair of electrodes 84 and 86, and a voltage sensor 88.

  The resistor 80 is connected between the internal power supply 31 (see FIG. 1) and the electrode 84. The resistor 82 is connected between the electrode 86 and the ground potential.

  The electrodes 84 and 86 are each formed in a comb shape including comb teeth, and the electrode 84 and the electrode 86 are disposed with their comb teeth facing each other. Specifically, the comb teeth of the electrode 84 and the comb teeth of the electrode 86 are alternately arranged along one surface of the insulating substrate of the DC / DC converter 30.

  Voltage sensor 88 detects voltage Vd across resistor 82 and outputs the detected voltage Vd to ECU 40.

  As shown in FIG. 3, when dew condensation 90 occurs between the comb teeth of the electrodes 84 arranged alternately and the comb teeth of the electrode 86, the insulation resistance between the electrode 84 and the electrode 86. Decreases and a leakage path is formed. As a result, a current Id flows through the resistor 82, and a voltage Vd that is the product of the current Id and the resistance value is generated at both ends thereof.

  The current Id increases as the insulation resistance between the electrodes 84 and 86 decreases, that is, as the degree of condensation increases. Therefore, ECU 40 can detect the degree of condensation of DC / DC converter 30 based on the voltage level of voltage Vd received from voltage sensor 88.

FIG. 4 is a functional block diagram of the leak determination means included in ECU 40 shown in FIG.
Referring to FIG. 4, leak determination means 42 includes a determination reference current setting unit 420 and a comparator 422.

  Determination reference current setting unit 420 sets determination reference current Iref based on voltage Vd from voltage sensor 88 and inputs the set determination reference current Iref to one input of comparator 422. The current Ir is input from the current sensor 38 (FIG. 1) to the other input of the comparator 422.

  The comparator 422 compares the determination reference current Iref with the current Ir. Specifically, when current Ir is higher than determination reference current Iref, comparator 422 determines that a leak current is generated in MOS transistor 35 and activates signal DET indicating the determination result to H level. To do. On the other hand, when current Ir is equal to or smaller than determination reference current Iref, it is determined that no leak current is generated in MOS transistor 35, and signal DET indicating the determination result is deactivated to L level. The H level or L level signal DET is output to the relay control means 44 included in the ECU 40.

  When receiving an H level signal from the ignition key, relay control means 44 generates an H level signal SE1 and outputs the generated H level signal SE1 to system main relay SMR1. When the relay control unit 44 receives the L-level signal DET from the leak determination unit 42, the relay control unit 44 generates an H-level signal DRV and outputs it to the drive circuit. Thereafter, when voltage Vc reaches a predetermined precharge voltage, H level signal SE2 is generated and output to system main relay SMR2, and after system main relay SMR2 is turned on, L level signal DRV is generated and driven. Output to the circuit, and the MOS transistor 35 is turned off.

  Here, in the present embodiment, it is assumed that the determination reference current Iref used by the leak determination means 42 is set based on the relationship between the preset voltage Vd and the determination reference current Iref.

FIG. 5 is a diagram illustrating a relationship between the voltage Vd and the determination reference current Iref.
Referring to FIG. 5, determination reference current Iref is fixed to a predetermined threshold current I_std for voltage Vd lower than a predetermined threshold voltage V_std. The predetermined threshold voltage V_std is set to a voltage Vd corresponding to the degree of condensation that does not affect the determination accuracy.

  When the voltage Vd exceeds a predetermined threshold voltage V_std, the determination reference current Iref is set to increase as the voltage Vd increases. Thus, by setting the determination reference current Iref to increase in proportion to the voltage Vd, when the voltage Vd is high, that is, when the degree of condensation is large, the current Ir flowing through the resistor 36 is determined as the determination reference current. It is possible to prevent erroneous determination that a leak current is generated in the MOS transistor 35, assuming that it exceeds Iref.

  Further, when the degree of condensation decreases due to a temperature increase due to self-heating of the MOS transistor 35, the determination reference current Iref is set to decrease as the voltage Vd decreases according to the relationship of FIG. Thus, it is possible to accurately determine whether or not a leak current is generated in the MOS transistor 35 after the condensation has been eliminated.

  The determination reference current setting unit 420 stores the relationship between the voltage Vd and the determination reference current Iref in FIG. 5 in advance in a storage area (not shown) as a determination reference current setting map, and determines that the voltage Vd is given. The corresponding determination reference current Iref is extracted from the reference current setting map and set as the determination reference current Iref. Then, the determination reference current setting unit 420 outputs the set determination reference current Iref to the comparator 422.

  FIG. 6 is a flowchart for explaining the operation for determining the occurrence of leakage current in MOS transistor 35 according to the embodiment of the present invention.

  Referring to FIG. 6, ECU 40 receives H level signal IG from the ignition key in response to the ignition key being turned on (step S01). Then, ECU 40 generates H-level signal SE1 and outputs it to system main relay SMR1, and turns on only system main relay SMR1 (step S02).

  Next, when the ECU 40 acquires the voltage Vd across the resistor 82 from the dew condensation sensor 39 (step S03), the determination reference corresponding to the acquired voltage Vd is stored from the determination reference current setting map stored in the storage area in advance. The current Iref is extracted and set as the determination reference current Iref (step S04).

  Thereafter, when the ECU 40 acquires the current Ir flowing through the resistor 36 from the current sensor 38 (step S05), the ECU 40 determines whether or not the acquired current Ir exceeds the determination reference current Iref set in step S04 (step S06). ). In step S06, when it is determined that the current Ir exceeds the determination reference current Iref, the ECU 40 determines that a leak current is generated in the MOS transistor 35. Then, ECU 40 generates L level signal SE1 and outputs it to system main relay SMR1. System main relay SMR1 is turned off in response to L level signal SE1 (step S07). Further, the ECU 40 generates a signal EMG and outputs it to the display means 60 (step S08). The display means 60 displays “abnormal” in response to the signal EMG.

  On the other hand, when it is determined in step S06 that the current Ir is equal to or less than the determination reference current Iref, the ECU 40 determines that no leak current is generated in the MOS transistor 35. Then, system main relay SMR2 and drive circuit 37 are controlled to precharge capacitor 22 (step S09). Thereafter, when the precharge of the capacitor 22 is completed, the ECU 40 generates a signal PWM for driving the inverter 21 of the IPM 20, and outputs the generated signal PWM to the inverter 21 (step S10). Inverter 21 converts DC voltage from capacitor 22 into AC voltage based on signal PWM from ECU 40 to drive motor generator MG.

  In the present embodiment, inverter 21 and capacitor 22 constitute a “drive circuit”, and system main relays SMR1, SMR2, inverter 21 and capacitor 22 constitute a “motor drive device”.

  The DC / DC converter 30 constitutes a “voltage converter”, and the ECU 40 realizes “leak determination means” and “determination reference value setting means”.

[Example of change]
FIG. 7 is a functional block diagram for explaining a modified example of the leak determination means 42 included in the ECU 40 shown in FIG.

  Referring to FIG. 7, leak determination means 42 </ b> A according to this modification includes a determination reference time setting unit 424 and a leak determination unit 426.

  Determination reference time setting unit 424 sets determination reference time Tref based on voltage Vd from voltage sensor 88 included in dew condensation sensor 39 and outputs the set determination reference time Tref to leak determination unit 426.

  In this modification, the leak determination means 42A is configured to vary the determination reference time Tref for determining whether or not a leak current is generated in the MOS transistor 35 according to the voltage Vd.

  Specifically, in this modification example, whether or not the leakage current is generated in the MOS transistor 35 is determined when the current Ir exceeds the predetermined determination reference current Iref exceeds the predetermined determination reference time Tref. When this is continued, it is determined by determining that a leak current is generated in the MOS transistor 35.

  According to this, when the current Ir temporarily exceeds the determination reference current Iref, such as when noise is mixed in the current Ir from the current sensor 38, the leak current in the MOS transistor 35 is erroneously generated. It is possible to prevent the determination.

  FIG. 8 is a timing chart for explaining an operation for determining whether or not a leak current is generated in the MOS transistor 35 according to this modification.

  Referring to FIG. 8, when the system main relay SMR1 is turned on at timing t2 following the ignition key being turned on at timing t1, the current sensor 38 detects the current Ir flowing through the resistor 36 and leaks. The data is output to the determination unit 426.

  Leak determination unit 426 determines that a leak current is generated in MOS transistor 35 when it is determined that the state where current Ir exceeds determination reference current Iref continues beyond determination reference time Tref. To do.

  Here, when condensation occurs in the MOS transistor 35, it may be determined that a leakage current in the MOS transistor 35 is erroneously generated depending on the length of the determination reference time Tref.

  That is, as described above, the dew condensation generated in the MOS transistor 35 is eliminated as the element temperature increases due to self-heating, but the time required until the dew condensation is eliminated is longer than the determination reference time Tref. In this case, the state where the current Ir exceeding the determination reference current Iref continues to flow beyond the determination reference time Tref is erroneously determined as a leakage current occurring in the MOS transistor 35.

  Therefore, in the modified example, the determination reference time Tref for determining whether or not a leak current is generated in the MOS transistor 35 is set according to the degree of condensation of the DC / DC converter 30. For example, the determination reference time Tref is set based on the relationship between the preset voltage Vd and the determination reference time Tref.

FIG. 9 is a diagram for explaining the relationship between the voltage Vd and the determination reference time Tref.
Referring to FIG. 9, determination reference time Tref is fixed to predetermined threshold time T_std for voltage Vd that is lower than predetermined threshold voltage V_std. The predetermined threshold voltage V_std is set to a voltage Vd corresponding to the degree of condensation that does not affect the determination accuracy.

  When the voltage Vd exceeds a predetermined threshold voltage V_std, the determination reference time Tref is set to increase as the voltage Vd increases. Thus, by setting the determination reference time Tref so as to increase in proportion to the voltage Vd, when the voltage Vd is high, that is, when the degree of condensation is large, the current Ir exceeds the determination reference current Iref. It is possible to prevent the leakage current in the MOS transistor 35 from being erroneously determined to be present, assuming that the current state continues beyond the determination reference time Tref.

  If the state where the current Ir exceeds the determination reference current Iref continues even after the condensation is eliminated by the self-heating of the MOS transistor 35, the leakage determination unit 426 determines the duration time. In response to exceeding the reference time Tref, it is determined that a leak current is generated in the MOS transistor 35. That is, according to this modified example, it is possible to accurately determine whether or not a leakage current is generated in the MOS transistor 35 after the condensation is eliminated.

  Note that the determination reference time setting unit 424 stores the relationship between the voltage Vd and the determination reference time Tref in FIG. 9 in advance in a storage area (not shown) as a determination reference time setting map, and determines that the voltage Vd is given. The corresponding determination reference time Tref is extracted from the reference time setting map and set as the determination reference time Tref. Then, the determination reference time setting unit 424 outputs the set determination reference time Tref to the leak determination unit 426.

  FIG. 10 is a flowchart for explaining the operation for determining the occurrence of leakage current in the MOS transistor 35 according to this modification.

  Referring to FIG. 10, ECU 40A receives H-level signal IG from the ignition key in response to the ignition key being turned on (step S11). Then, ECU 40A generates H-level signal SE1 and outputs it to system main relay SMR1, and turns on only system main relay SMR1 (step S12).

  Next, when the ECU 40A acquires the voltage Vd across the resistor 82 from the dew condensation sensor 39 (step S13), the determination reference corresponding to the acquired voltage Vd from the determination reference time setting map stored in advance in the storage area. The time Tref is extracted and set as the determination reference time Tref (step S14).

  Thereafter, when the ECU 40A acquires the current Ir flowing through the resistor 36 from the current sensor 38 (step S15), the ECU 40A determines whether or not the acquired current Ir exceeds a predetermined determination reference current Iref (step S16).

  When it is determined in step S16 that the current Ir exceeds the determination reference current Iref, the ECU 40A subsequently counts the duration Tr (FIG. 8) in which the current Ir exceeds the determination reference current Iref. Then, it is determined whether or not the counted duration time Tr exceeds the determination reference time Tref set in step S14 (step S17).

  In step S17, when it is determined that the duration time Tr exceeds the determination reference time Tref, the ECU 40A determines that a leak current is generated in the MOS transistor 35. Then, ECU 40A generates L level signal SE1 and outputs it to system main relay SMR1. System main relay SMR1 is turned off in response to L level signal SE1 (step S18). Further, the ECU 40A generates a signal EMG and outputs it to the display means 60 (step S19). The display means 60 displays “abnormal” in response to the signal EMG.

  On the other hand, when it is determined in step S16 that the current Ir is equal to or less than the determination reference current Iref, or when it is determined in step S17 that the duration Tr is equal to or less than the determination reference time Tref, the ECU 40A 35, it is determined that no leakage current has occurred. Then, system main relay SMR2 and drive circuit 37 are controlled to precharge capacitor 22 (step S20). Thereafter, when precharging of capacitor 22 is completed, ECU 40A generates a signal PWM for driving inverter 21 of IPM 20, and outputs the generated signal PWM to inverter 21 (step S21). Inverter 21 converts DC voltage from capacitor 22 into AC voltage based on signal PWM from ECU 40 to drive motor generator MG.

  As described above, according to the first embodiment of the present invention, it is accurately determined whether or not a leakage current is generated in the MOS transistor included in the DC / DC converter regardless of the degree of condensation in the DC / DC converter. Can be determined. As a result, the precharge of the capacitor 22 can be accurately controlled.

[Embodiment 2]
FIG. 11 is a schematic block diagram of a drive system according to Embodiment 2 of the present invention.

  Referring to FIG. 11, drive system 100B is the same as drive system 100 except that ECU 40 in the drive system of FIG. The ECU 40B is the same as the ECU 40 except that the leak determination means 42 (FIG. 4) included in the ECU 40 is replaced with a leak determination means 42B, as will be described below.

  FIG. 12 is a functional block diagram of leak determination means 42B included in ECU 40B in FIG.

  Referring to FIG. 12, leak determination means 42 </ b> B includes a dew condensation determination unit 428, a voltage converter drive unit 430, and a leak determination unit 426.

  When the condensation determination unit 428 receives the voltage Vd from the voltage sensor 88 included in the condensation sensor 39, the condensation determination unit 428 determines whether or not the received voltage Vd exceeds a predetermined reference voltage Vref. When it is determined that the voltage Vd exceeds the predetermined reference voltage Vref, the dew condensation determination unit 428 determines that dew condensation has occurred in the DC / DC converter 30 and generates a signal DS indicating the determination result. It is generated and output to the voltage converter driver 430.

  When the voltage converter driving unit 430 receives the signal DS from the dew condensation determination unit 428, the voltage converter driving unit 430 generates a signal PWR for driving the voltage converter 33 in the DC / DC converter 30, and the generated signal PWR is used as the control circuit 32. Output to.

  In the DC / DC converter 30, when the control circuit 32 receives the signal PWR from the voltage converter driving unit 430, it generates a signal for controlling voltage conversion in the voltage converter 33, and the generated signal is used as the voltage converter 33. Output to. Thus, voltage converter 33 converts the DC voltage received from battery 10 in accordance with the control from control circuit 32, and supplies the converted DC voltage to a load such as an auxiliary battery (not shown).

  More specifically, the voltage converter 33 is configured by a chopper circuit, for example. The chopper circuit includes a pair of switching elements connected in series between a positive bus and a negative bus, and performs voltage conversion according to a duty ratio that is a ratio of turning on / off the pair of switching elements. The duty ratio is controlled by the control circuit 32.

  The pair of switching elements are turned on / off under the control of the control circuit 32, so that heat loss occurs in the voltage converter 33. The generated heat loss is transmitted to the insulating substrate of the DC / DC converter 30 on which the voltage converter 33 is mounted, so that the temperature of the substrate rises. As a result, the condensation of the DC / DC converter 30 is eliminated.

  When the voltage Vd is reduced to be equal to or lower than the predetermined reference voltage Vref due to elimination of condensation in the DC / DC converter 30, the condensation determination unit 428 does not cause condensation in the DC / DC converter 30. And a signal NDS indicating the determination result is generated and output to the relay control means 44. Relay control means 44 generates H-level signal SE1 in response to signal NDS from dew condensation determination unit 428, outputs it to system main relay SMR1, and turns on only system main relay SMR1.

  Thereafter, leak determination unit 426 determines whether or not a leak current is generated in MOS transistor 35 based on current Ir flowing through resistor 36 after only system main relay SMR1 is turned on. When it is determined that no leak current is generated in the MOS transistor 35, the capacitor 22 is precharged by the method described above.

  As described above, according to the present embodiment, when the ignition key is turned on, the process for eliminating the dew condensation that first occurred in the DC / DC converter 30 is performed. Then, it is determined whether or not a leak current is generated in the MOS transistor 35 in accordance with the elimination of condensation. According to this, since the determination as to whether or not the leakage current is generated in the MOS transistor 35 is executed in a state where condensation is surely eliminated, it is determined whether or not the leakage current is generated in the MOS transistor 35. It can be determined accurately. As a result, the precharge of the capacitor 22 can be accurately controlled.

  FIG. 13 is a flowchart for explaining the operation for determining the occurrence of leakage current in MOS transistor 35 according to the embodiment of the present invention.

  Referring to FIG. 13, when ECU 40B receives H level signal IG from the ignition key in response to the ignition key being turned on (step S31), ECU 40B obtains voltage Vd across resistor 82 from dew condensation sensor 39. (Step S32). Then, the ECU 40B determines whether or not the acquired voltage Vd exceeds a predetermined reference voltage Vref (step S33).

  When it is determined in step S33 that the voltage Vd exceeds the predetermined reference voltage Vref, the ECU 40B generates a signal PWR for driving the voltage converter 33 included in the DC / DC converter 30 to generate a control circuit. (Step S34). When receiving the signal PWR, the control circuit 32 controls the duty ratio of the pair of switching elements included in the voltage converter 33.

  Thereafter, when the voltage converter 33 performs voltage conversion according to the duty ratio, the substrate temperature of the DC / DC converter 30 rises and the condensation of the DC / DC converter 30 is eliminated. In response to being equal to or lower than the predetermined reference voltage Vref (step S33), an H level signal SE1 is generated and output to the system main relay SMR1, and only the system main relay SMR1 is turned on (step S35).

  Thereafter, when the ECU 40B acquires the current Ir flowing through the resistor 36 from the current sensor 38 (step S36), the ECU 40B determines whether or not the acquired current Ir exceeds a predetermined determination reference current Iref (step S37).

  When it is determined in step S37 that the current Ir exceeds the determination reference current Iref, the ECU 40B further counts the duration Tr (FIG. 8) in which the current Ir exceeds the determination reference current Iref. It is determined whether or not the counted duration time Tr exceeds a predetermined determination reference time Tref (step S38).

  When it is determined in step S38 that the duration time Tr exceeds the determination reference time Tref, the ECU 40B determines that a leak current is generated in the MOS transistor 35. ECU 40B generates L level signal SE1 and outputs it to system main relay SMR1. System main relay SMR1 is turned off in response to L level signal SE1 (step S39). Further, the ECU 40B generates a signal EMG and outputs it to the display means 60 (step S40). The display means 60 displays “abnormal” in response to the signal EMG.

  On the other hand, when it is determined in step S37 that the current Ir is equal to or less than the determination reference current Iref, or when it is determined in step S38 that the duration Tr is equal to or less than the determination reference time Tref, the ECU 40B 35, it is determined that no leakage current has occurred. Then, system main relay SMR2 and drive circuit 37 are controlled to precharge capacitor 22 (step S41). Thereafter, when the precharge of the capacitor 22 is completed, the ECU 40B generates a signal PWM for driving the inverter 21 of the IPM 20, and outputs the generated signal PWM to the inverter 21 (step S42). Inverter 21 converts DC voltage from capacitor 22 into AC voltage based on signal PWM from ECU 40B, and drives motor generator MG.

  In the present embodiment, the DC / DC converter 30 constitutes a “voltage converter”, and the ECU 40B realizes “leak determination means”, “condensation determination means”, and “temperature rise means”.

[Example of change]
About the process for eliminating the dew condensation which generate | occur | produced in the DC / DC converter 30, it shall be set as the structure which heats up the DC / DC converter 30 using the air in the air-conditioned vehicle interior so that it may describe in the following modified examples. Is also possible.

  FIG. 14 is a schematic block diagram of a drive system according to a modification of the second embodiment of the present invention.

  Referring to FIG. 14, drive system 100C is the same as drive system 100B except that battery pack 50 is replaced with battery pack 50C and ECU 40B is replaced with ECU 40C in drive system 100B of FIG. .

  The battery pack 50C is provided with a cooling device for cooling the battery 10 and the DC / DC converter 30 housed in the battery pack 50C. Specifically, the cooling device accommodates the battery 10 and the DC / DC converter 30, and in the battery pack 50C via an unillustrated battery pack 50C and a battery pack 50C constituting a passage of air supplied to the battery 10 and the DC / DC converter 30. Cooling air in which heat is exchanged between the cooling fan 300 for blowing the introduced air in the vehicle interior to the battery 10 and the DC / DC converter 30 as cooling air and the battery 10 and the DC / DC converter 30 And an exhaust port 302 for discharging the battery pack 50 to the outside.

  In the cooling device having the above configuration, the amount of cooling air blown by the cooling fan 300 is controlled by the ECU 40C. Specifically, the ECU 40C receives the air condition (temperature, humidity, etc.) AC of the vehicle interior from the air conditioner 62 provided in the vehicle interior, and sets the device temperatures of the battery 10 and the DC / DC converter 30 from temperature sensors (not shown). When received, the amount of cooling air blown in the cooling fan 300 is controlled so as to keep the battery 10 and the DC / DC converter 30 in an appropriate temperature range based on these pieces of information.

  Further, as described below, the ECU 40C determines whether or not condensation has occurred in the DC / DC converter 30 based on the voltage Vd from the condensation sensor 39 after the ignition key is turned on. When it is determined that condensation occurs in the DC / DC converter 30, the ECU 40 </ b> C controls the cooling fan 300 so that the air in the passenger compartment warmed by the air conditioner 62 is blown to the DC / DC converter 30. To do.

  FIG. 15 is a functional block diagram of leak determination means 42C included in ECU 40C in FIG.

  Referring to FIG. 15, leak determination means 42C is the same as leak determination means 42B except that voltage converter drive section 430 in leak determination means 42B of FIG. 12 is replaced with fan drive section 432. is there.

  When the condensation determination unit 428 receives the voltage Vd from the voltage sensor 88 included in the condensation sensor 39, the condensation determination unit 428 determines whether or not the received voltage Vd exceeds a predetermined reference voltage Vref. When it is determined that the voltage Vd exceeds the predetermined reference voltage Vref, the dew condensation determination unit 428 determines that dew condensation has occurred in the DC / DC converter 30 and generates a signal DS indicating the determination result. It is generated and output to the fan drive unit 432.

  Upon receiving the signal DS from the dew condensation determination unit 428, the fan drive unit 432 generates a signal FC for driving and controlling the cooling fan 300 provided in the battery pack 50C, and outputs the generated signal FC to the cooling fan 300. To do.

  The cooling fan 300 is driven in accordance with a signal FC from the fan driving unit 432. Thereby, the air in the passenger compartment warmed by the air conditioner 62 is blown to the DC / DC converter 30. As a result, the DC / DC converter 30 is heated by exchanging heat with the air in the passenger compartment, so that the condensation of the DC / DC converter 30 is eliminated.

  In addition, about the ventilation volume of the air from the cooling fan 300 at this time, dew condensation of the DC / DC converter 30 based on the state AC of the vehicle interior air from the air conditioner 62 and the apparatus temperature of the DC / DC converter 30 The ECU 40C controls the air flow so that the air flow can be eliminated.

  When the voltage Vd is reduced to be equal to or lower than the predetermined reference voltage Vref due to elimination of condensation in the DC / DC converter 30, the condensation determination unit 428 does not cause condensation in the DC / DC converter 30. And a signal NDS indicating the determination result is generated and output to the relay control means 44. Relay control means 44 generates H-level signal SE1 in response to signal NDS from dew condensation determination unit 428, outputs it to system main relay SMR1, and turns on only system main relay SMR1.

  Thereafter, leak determination unit 426 determines whether or not a leak current is generated in MOS transistor 35 based on current Ir flowing through resistor 36 after only system main relay SMR1 is turned on. When it is determined that no leak current is generated in the MOS transistor 35, the capacitor 22 is precharged by the method described above.

  FIG. 16 is a flowchart for explaining the operation for determining the occurrence of a leak current in the MOS transistor 35 according to this modification.

  Referring to FIG. 16, when ECU 40C receives H level signal IG from the ignition key in response to the ignition key being turned on (step S51), ECU 40C obtains voltage Vd across resistor 82 from dew condensation sensor 39. (Step S52). Then, ECU 40C determines whether or not the acquired voltage Vd exceeds a predetermined reference voltage Vref (step S53).

  When it is determined in step S53 that the voltage Vd is higher than the predetermined reference voltage Vref, the ECU 40C generates a signal FC for driving and controlling the cooling fan 300 provided in the battery pack 50 to generate the cooling fan 300. (Step S54). The cooling fan 300 is driven according to the signal FC, and blows the air in the passenger compartment warmed by the air conditioner 62 to the DC / DC converter 30.

  Thereafter, when the DC / DC converter 30 is warmed by exchanging heat with the air in the vehicle interior that has been blown to eliminate condensation, the ECU 40C causes the voltage Vd to become equal to or lower than the predetermined reference voltage Vref. In response (step S53), an H level signal SE1 is generated and output to system main relay SMR1, and only system main relay SMR1 is turned on (step S55).

  Thereafter, when the ECU 40C acquires the current Ir flowing through the resistor 36 from the current sensor 38 (step S56), the ECU 40C determines whether or not the acquired current Ir exceeds a predetermined determination reference current Iref (step S57).

  When it is determined in step S57 that the current Ir exceeds the determination reference current Iref, the ECU 40C further counts the duration Tr (FIG. 8) in which the current Ir exceeds the determination reference current Iref. It is determined whether or not the counted duration time Tr exceeds a predetermined determination reference time Tref (step S58).

  In step S58, when it is determined that the duration Tr exceeds the determination reference time Tref, the ECU 40C determines that a leak current is generated in the MOS transistor 35. Then, ECU 40C generates L level signal SE1 and outputs it to system main relay SMR1. System main relay SMR1 is turned off in response to L level signal SE1 (step S59). Further, the ECU 40C generates a signal EMG and outputs it to the display means 60 (step S60). The display means 60 displays “abnormal” in response to the signal EMG.

  On the other hand, when it is determined in step S57 that the current Ir is equal to or less than the determination reference current Iref, or when it is determined in step S58 that the duration Tr is equal to or less than the determination reference time Tref, the ECU 40C 35, it is determined that no leakage current has occurred. Then, system main relay SMR2 and drive circuit 37 are controlled to precharge capacitor 22 (step S61). Thereafter, when precharging of capacitor 22 is completed, ECU 40C generates a signal PWM for driving inverter 21 of IPM 20, and outputs the generated signal PWM to inverter 21 (step S62). Inverter 21 converts DC voltage from capacitor 22 into AC voltage based on signal PWM from ECU 40C, and drives motor generator MG.

  As described above, according to the second embodiment of the present invention, whether or not the leakage current is generated in the MOS transistor included in the DC / DC converter in response to the elimination of the condensation in the DC / DC converter. Therefore, it is possible to accurately determine whether or not a leak current is generated in the MOS transistor included in the DC / DC converter. As a result, the precharge of the capacitor 22 can be accurately controlled.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 is a schematic block diagram of a drive system according to Embodiment 1 of the present invention. 2 is a timing chart of operations of a system main relay and a MOS transistor shown in FIG. It is a circuit diagram of the dew condensation sensor in FIG. It is a functional block diagram of the leak determination means contained in ECU40 shown in FIG. It is a figure which shows the relationship between the voltage Vd and the determination reference current Iref. 5 is a flowchart for explaining an operation for determining occurrence of a leak current in the MOS transistor according to the first embodiment of the present invention; FIG. 5 is a functional block diagram for explaining a modification example of a leak determination means included in the ECU shown in FIG. 4. It is a timing chart for demonstrating the determination operation | movement of whether the leak current has generate | occur | produced in the MOS transistor by the modification of Embodiment 1 of this invention. It is a figure for demonstrating the relationship between the voltage Vd and determination reference time Tref. It is a flowchart for demonstrating the operation | movement which determines generation | occurrence | production of the leakage current in the MOS transistor by the modification of Embodiment 1 of this invention. It is a schematic block diagram of the drive system by Embodiment 2 of this invention. It is a functional block diagram of the leak determination means contained in ECU in FIG. It is a flowchart for demonstrating the operation | movement which determines generation | occurrence | production of the leakage current in the MOS transistor by Embodiment 2 of this invention. It is a schematic block diagram of the drive system by the modification of Embodiment 2 of this invention. It is a functional block diagram of the leak determination means 42C contained in ECU in FIG. It is a flowchart for demonstrating the operation | movement which determines generation | occurrence | production of the leakage current in the MOS transistor by the modification of Embodiment 2 of this invention.

Explanation of symbols

  10 battery, 13 positive bus, 14 negative bus, 15 voltage sensor, 16 current sensor, 21 inverter, 22 capacitor, 30 converter, 31 internal power supply, 32 control circuit, 33 voltage converter, 34 diode, 35 MOS transistor, 36 resistance , 37 drive circuit, 38 current sensor, 39 condensation sensor, 42, 42A, 42B, 42C leak determination means, 44 relay control means, 50, 50C battery pack, 60 display means, 62 air conditioner, 80, 82 resistance, 84, 86 Electrode, 88 Voltage sensor, 90 Condensation, 100, 100B, 100C Drive system, 300 Cooling fan, 302 Exhaust port, 420 Judgment reference current setting unit, 422 Comparator, 424 Judgment reference time setting unit, 426 Leakage judgment unit, 428 Condensation determination unit, 43 Voltage converter driving unit, 432 fan drive, MG motor generator, SMR1, SMR2 system main relay.

Claims (16)

A voltage conversion device that receives a DC voltage from a power source that supplies power to a drive circuit of a load and converts the voltage level of the received DC voltage,
A voltage converter that converts a voltage level of the DC voltage received from the power source;
A semiconductor switching element connected in parallel with either one of the first and second relays connected in the positive bus and the negative bus between the power source and the capacitor included in the drive circuit;
Between the power source and the capacitor, connected in parallel with the one relay, and a resistor connected in series with the semiconductor switching element,
A current sensor that detects a current flowing through the resistor and outputs a current detection value;
Leak determination means for determining whether or not a leakage current is generated in the semiconductor switching element by comparing the current detection value with a determination reference value;
A condensation sensor for detecting a degree of condensation in the voltage converter,
The leak determination unit includes a determination reference value setting unit that makes the determination reference value variable according to the degree of condensation detected by the dew condensation sensor. The determination reference value includes a determination reference current for comparing the magnitude with the current detection value,
The determination reference value setting means sets the determination reference current such that the determination reference current increases as the degree of condensation detected by the dew condensation sensor increases.
The leak determination unit determines that the leak current is generated in the semiconductor switching element when the current detection value exceeds the determination reference current set by the determination reference value setting unit. Item 2. The voltage converter according to Item 1. The determination reference value includes a determination reference time for comparing a period in which a state exceeding a predetermined determination reference current continues with the current detection value,
The determination reference value setting means sets the determination reference time so that the determination reference time becomes longer as the degree of condensation detected by the dew condensation sensor increases.
When the leak determination means determines that the state where the current detection value exceeds the predetermined determination reference current continues beyond the determination reference period set by the determination reference value setting means The voltage converter according to claim 1, wherein it is determined that the leakage current is generated. A voltage conversion device that receives a DC voltage from a power source that supplies power to a drive circuit of a load and converts the voltage level of the received DC voltage,
A voltage converter that converts a voltage level of the DC voltage received from the power source;
A semiconductor switching element connected in parallel with any one of the first and second relays connected in the positive bus and the negative bus between the power source and the drive circuit;
Between the power supply and the drive circuit, a resistor connected in parallel with the one relay, and connected in series with the semiconductor switching element,
A current sensor that detects a current flowing through the resistor and outputs a current detection value;
Condensation determination means for determining whether or not condensation has occurred in the voltage converter;
Leak determination for determining whether or not a leakage current is generated in the semiconductor switching element based on the current detection value when it is determined by the condensation determination means that no condensation has occurred in the voltage converter. And a voltage converter.   The voltage according to claim 4, further comprising a temperature raising unit configured to raise the temperature of the voltage conversion device when it is determined by the condensation determination unit that condensation has occurred in the voltage conversion device. Conversion device.   The voltage converter according to claim 5, wherein the temperature raising unit performs drive control of the voltage converter when it is determined by the dew condensation determining unit that condensation has occurred in the voltage converter. A blower mechanism configured to blow air to the voltage converter;
The temperature raising means controls the blower mechanism so as to blow air to the voltage converter when it is determined by the condensation determiner that condensation has occurred in the voltage converter. The voltage converter described in 1. A drive circuit for turning on / off the semiconductor switching element;
The drive circuit is configured to determine that the leakage current is not generated in the semiconductor switching element when the other relay of the first and second relays is closed when the load is started. 8. The voltage conversion device according to claim 1, wherein the semiconductor switching element is turned on, and the semiconductor switching element is turned off when the voltage of the capacitor reaches a predetermined voltage. 9. Power supply,
A motor driving device for driving the motor generator by the first DC voltage received from the power source;
A positive bus and a negative bus connecting the power source and the motor driving device;
A voltage converter that is connected in parallel to the motor drive device and converts the first DC voltage received from the power source into a second DC voltage;
The motor driving device is
A drive circuit that includes a capacitor on the power supply side and converts the first DC voltage into an AC voltage to drive the motor generator;
First and second relays connected between the power source and the capacitor in the positive bus and the negative bus, respectively,
The voltage converter is
A voltage converter for converting the first DC voltage into the second DC voltage;
A semiconductor switching element connected in parallel with one of the first and second relays;
Between the power source and the capacitor, connected in parallel with the one relay, and a resistor connected in series with the semiconductor switching element,
A current sensor that detects a current flowing through the resistor and outputs a current detection value;
Leak determination means for determining whether or not a leakage current is generated in the semiconductor switching element by comparing the current detection value with a determination reference value;
A dew condensation sensor for detecting the degree of dew condensation in the voltage converter,
The leak determination means includes a determination reference value setting means for making the determination reference value variable according to the degree of condensation detected by the condensation sensor. The determination reference value includes a determination reference current for comparing the magnitude with the current detection value,
The determination reference value setting means sets the determination reference current such that the determination reference current increases as the degree of condensation detected by the dew condensation sensor increases.
The leak determination unit determines that the leak current is generated in the semiconductor switching element when the current detection value exceeds the determination reference current set by the determination reference value setting unit. Item 10. The drive system according to Item 9. The determination reference value includes a determination reference time for comparing a period in which a state exceeding a predetermined determination reference current continues with the current detection value,
The determination reference value setting means sets the determination reference time so that the determination reference time becomes longer as the degree of condensation detected by the dew condensation sensor increases.
When the leak determination means determines that the state where the current detection value exceeds the predetermined determination reference current continues beyond the determination reference period set by the determination reference value setting means The drive system according to claim 9, wherein it is determined that the leak current is generated. Power supply,
A motor driving device for driving the motor generator by the first DC voltage received from the power source;
A positive bus and a negative bus connecting the power source and the motor driving device;
A voltage converter that is connected in parallel to the motor drive device and converts the first DC voltage received from the power source into a second DC voltage;
The motor driving device is
A drive circuit that includes a capacitor on the power supply side and converts the first DC voltage into an AC voltage to drive the motor generator;
First and second relays connected between the power source and the capacitor in the positive bus and the negative bus, respectively,
The voltage converter is
A voltage converter for converting the first DC voltage into the second DC voltage;
A semiconductor switching element connected in parallel with one of the first and second relays;
Between the power source and the capacitor, connected in parallel with the one relay, and a resistor connected in series with the semiconductor switching element,
A current sensor that detects a current flowing through the resistor and outputs a current detection value;
Condensation determination means for determining whether or not condensation has occurred in the voltage converter;
Leak determination for determining whether or not a leakage current is generated in the semiconductor switching element based on the current detection value when it is determined by the condensation determination means that no condensation has occurred in the voltage converter. And a drive system.   The voltage conversion device further includes a temperature raising unit configured to raise the temperature of the voltage conversion device when it is determined by the condensation determination unit that condensation has occurred in the voltage conversion device. Item 13. The drive system according to Item 12.   The drive system according to claim 13, wherein the temperature raising unit performs drive control of the voltage converter when it is determined by the dew condensation determination unit that dew condensation has occurred in the voltage converter. The voltage converter further includes a blowing mechanism configured to blow air to the voltage converter,
The temperature raising means controls the blower mechanism so as to blow air to the voltage converter when it is determined by the condensation determiner that condensation has occurred in the voltage converter. Drive system as described in. The voltage conversion device further includes a drive circuit for turning on / off the semiconductor switching element,
The drive circuit determines that the leakage current is not generated in the semiconductor switching element when one of the first and second relays is closed when the load is started. The drive system according to claim 9, wherein the semiconductor switching element is turned on and the semiconductor switching element is turned off when the voltage of the capacitor reaches a predetermined voltage.

Images