JP2008263763A - Vehicle semiconductor relay diagnosing apparatus and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor relay diagnosing apparatus with a circuit for preventing a false detection due to a disturbance as a dew condensation and an electromagnetic noise generated in the vicinity of a circuit for detecting a micro current. <P>SOLUTION: A motor drive system 100 has a dynamo-electric machine 12, an inverter 11, system main relays SMR1, SMR2, a MOSFET 21 as a semiconductor relay, a high voltage battery 18, a smoothing capacitor 15, a limiting resistor R0, a leakage current detecting circuit 10, the semiconductor relay diagnosing apparatus 14, and a motor controller 13. The leakage current detecting circuit 10 has voltage dividing resistors R1, R2 for detecting a leakage current IL flowing in the MOSFET 21 by use of a voltage across both terminals of the limiting resistor R0, a differential amplifier 16, a feedback resistor R3, and an actuation detecting circuit 17 for detecting an actuation condition of the MOSFET 21. The semiconductor relay diagnosing apparatus diagnoses the semiconductor relay based on these signals. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a vehicle semiconductor relay diagnostic apparatus and a diagnostic method for diagnosing an abnormality of a semiconductor relay provided between an inverter and a battery.

  In recent years, hybrid vehicles, fuel cell vehicles, electric vehicles, and the like have been developed and put to practical use as environmentally friendly vehicles. In particular, the hybrid vehicle uses an engine that is an internal combustion engine and a motor driven by a battery as power sources to improve fuel efficiency.

  A hybrid vehicle or the like is provided with an inverter that boosts the voltage of the battery to drive the motor and charges the battery with regenerative energy at the time of braking. An electromagnetic relay is provided on the low potential side.

  Since the inverter is equipped with a large-capacity capacitor for leveling the voltage, if the high-potential and low-potential electromagnetic relays are suddenly turned on, an inrush current flows through the uncharged capacitor and electromagnetic There is a risk of relay welding. In order to prevent such an inrush current from flowing, a precharge electromagnetic relay having a limiting resistance is conventionally provided in parallel with the high potential side electromagnetic relay, and before the high potential side electromagnetic relay is turned on, the precharge is performed. And the high potential side electromagnetic relay is turned on after the precharge is completed.

  The generation of electromagnetic relay operating noise when power is turned on not only impairs quietness but also increases the cost for soundproofing. In order to solve such a problem, Patent Document 1 discloses a power supply device using a low-cost and small-sized semiconductor relay (power MOSFET transistor) instead of the precharge electromagnetic relay.

  In addition, the use of semiconductor relays causes problems specific to semiconductor relays. Therefore, Patent Document 2 discloses a technology that realizes a load short-circuit protection function and an overcurrent protection function by detecting the potential of the drain terminal of the MOSFET in the semiconductor relay, and reduces the leakage current at the time of OFF that is unique to the semiconductor relay. It is disclosed.

JP 2006-304408 A JP 2002-43916 A

  However, although the circuit disclosed in Patent Document 2 has a voltage detection function on the low potential side, it does not have a semiconductor relay diagnosis function. In addition, if a circuit that detects the leakage current of a semiconductor relay is provided, there is a risk of erroneous detection due to electromagnetic noise sneaking into the circuit that detects a minute current or electromagnetic noise sneaking due to condensation due to increased humidity. .

  Therefore, the present invention provides a semiconductor relay diagnostic apparatus for detecting a leak failure by a minute current, and a semiconductor relay diagnosis having a circuit for preventing erroneous detection due to disturbance such as dew condensation near the circuit for detecting a minute current or wraparound of electromagnetic noise. An object is to provide an apparatus.

  To achieve the above object, a vehicle semiconductor relay diagnostic apparatus according to the present invention is provided with an electromagnetic relay and a semiconductor relay between an inverter and a battery, and diagnoses an abnormality of the semiconductor relay. In the diagnostic device, the semiconductor relay is arranged in parallel with the low potential electromagnetic relay provided between the low potential side of the battery and the low potential side of the inverter, and between the low potential side of the battery and the low potential side of the inverter. After the leakage current detecting means for detecting the leakage current by the voltage across the resistance elements connected in series and the high potential electromagnetic relay provided between the high potential side of the battery and the high potential side of the inverter are turned on Diagnosing means for diagnosing abnormality of the semiconductor relay based on the detected temporal change of the leakage current on the low potential side.

  Further, in the vehicle semiconductor relay diagnostic apparatus according to the present invention, calculation means for storing a time change of the leakage current detected by the leakage current detection means and calculating a steady value and a maximum / minimum value based on the stored leakage current. The diagnostic means uses the leakage current after the high-potential electromagnetic relay becomes conductive, and determines that the calculated state is a normal state when the calculated steady-state value is less than or equal to a predetermined value. .

  Furthermore, in the vehicular semiconductor relay diagnostic apparatus according to the present invention, the diagnostic means has a measured steady value exceeding a predetermined value, and the calculated steady value and the change amount of the maximum and minimum values exceed a predetermined value. It is characterized by determining a disturbance state.

  Furthermore, in the semiconductor relay diagnostic apparatus for a vehicle according to the present invention, the diagnostic means has a measured steady value exceeding a predetermined value, and the calculated steady value and the change amount of the maximum and minimum values are a predetermined value. In the following cases, a failure state is determined.

  A diagnostic method for a semiconductor relay diagnostic device for a vehicle according to the present invention includes: an electromagnetic relay and a semiconductor relay provided between an inverter and a battery; and the diagnostic method for a semiconductor relay diagnostic device for a vehicle that diagnoses an abnormality of the semiconductor relay. Arranged in parallel with a low potential electromagnetic relay provided between the low potential side of the inverter and the low potential side of the inverter, and connected in series with the semiconductor relay between the low potential side of the battery and the low potential side of the inverter The leakage current detecting step for detecting the leakage current by the voltage across the resistance element and the low potential detected after the high potential electromagnetic relay provided between the high potential side of the battery and the high potential side of the inverter becomes conductive. And a diagnostic step of diagnosing abnormality of the semiconductor relay based on the time change of the leakage current on the potential side.

  In the diagnostic method of the semiconductor relay diagnostic apparatus for a vehicle according to the present invention, the time change of the leakage current detected by the leakage current detecting means is stored, and the steady value and the maximum / minimum value are calculated based on the stored leakage current. The diagnostic step includes using a leakage current after the high-potential electromagnetic relay is turned on, and determining that the calculated steady-state value is equal to or less than a predetermined value is a normal state. And

  Furthermore, in the diagnostic method for a semiconductor relay diagnostic device for a vehicle according to the present invention, the diagnostic step includes a step in which the measured steady value exceeds a predetermined value, and the calculated steady value and the change amount of the maximum / minimum value are a predetermined value. It is characterized by determining a disturbance state when exceeding.

  Furthermore, in the diagnostic method of the semiconductor relay diagnostic device for a vehicle, the diagnostic step includes a measured steady value exceeding a predetermined value, and the calculated steady value and the change amount of the maximum and minimum values are equal to or less than the predetermined value. In this case, it is characterized in that a failure state is determined.

  By using the present invention, it is possible to prevent erroneous detection due to disturbances such as dew condensation in the vicinity of a circuit for detecting a minute current or electromagnetic noise, and the reliability of the diagnostic circuit is improved.

  Hereinafter, embodiments of the present invention (hereinafter referred to as embodiments) will be described with reference to the drawings.

  FIG. 1 is a configuration diagram of a motor drive system 100 mounted on a vehicle. The motor drive system 100 includes a rotating electrical machine 12 (motor / generator) that operates as a drive motor or a regenerative generator, an inverter 11, system main relays (SMR1, SMR2), a MOSFET 21 that is a semiconductor relay, It has a high-voltage battery 18, a smoothing capacitor 15, a limiting resistor R 0, a leak current detection circuit 10, a semiconductor relay diagnostic device 14, and a motor control device 13.

  The leakage current detection circuit 10 uses the leakage current IL flowing through the MOSFET 21 as a voltage across the limiting resistor R0 to detect the leakage current detection voltage dividing resistors R1 and R2, the differential amplifier 16, the feedback resistor R3, and the operation status of the MOSFET 21. And an operation detection circuit 17 for detection. The leak current detection circuit 10 outputs the detected leak current and the operating status of the MOSFET 21 to the semiconductor relay diagnostic device 14.

  Next, the connection relationship of each device is shown. One end of the system main relay SMR1 is connected to the high potential side of the battery 18, and one end of the system main relay SMR1 and one end of the limiting resistor R0 are connected to the low potential side of the battery 18, and the limiting resistor R0. Is connected to the source terminal of the MOSFET 21. Further, the other end of the system main relay SMR1, one end of the smoothing capacitor 15, and the high potential side of the inverter 11 are connected. Similarly, the other end of the system main relay SMR2 and the other end of the smoothing capacitor 15 are connected. The drain terminal of the MOSFET 21 and the low potential side of the inverter 11 are connected.

  The inverter 11 boosts the DC power of the battery 18 and converts it into a three-phase AC of U phase, V phase, and W phase, and each phase cable is connected to a rotating electrical machine 12 that operates with the three-phase AC. Further, the motor control device 13 controls the inverter 11 and the like according to signals such as an ignition switch (start S / W) (not shown) and the accelerator opening.

  FIG. 2 shows a leak voltage corresponding to the leak current detected by the semiconductor relay diagnostic device 14 and a determination condition based on the behavior of the measured value of the leak voltage. In the waveform shown in FIG. 2, the horizontal axis represents time, and the vertical axis represents leakage voltage. 1 amplifies the voltage at the midpoint A of the voltage dividing resistors R1 and R2 and outputs the amplified voltage to the semiconductor relay diagnostic device 14. When the MOSFET 21 is in a normal state, the A state is below the steady threshold value, and for example, a voltage value of about 2 mV is detected and output.

  Here, the steady threshold value is set to 5 mV, for example, but when electromagnetic noise wraps around a circuit that measures a minute voltage of about several mV, the output value of about 2 mV usually varies greatly. , And may vary with an amplitude of about 0 V to 1000 mV (1 V).

  In such a case, a leak voltage with a steady threshold value of 5 mV or more is erroneously detected as an abnormality of the semiconductor relay. Therefore, in the present embodiment, the minimum threshold value and the maximum threshold value are set, and the following processing is executed in order to identify a fluctuation in leakage voltage due to condensation or external noise and a failure. Specifically, after the signal amplified by the leakage current detection circuit is A / D converted by the semiconductor relay diagnostic device 14, the change amount or change rate of the maximum / minimum value is calculated, and changes beyond a predetermined width. In this case, it is determined that the state is a “singular state” due to noise, and the process of continuing the measurement to reduce false detection is executed.

  In general, when the MOSFET 21 fails, the MOSFET 21 is stabilized at a predetermined leakage voltage (“failure state” in the figure) and does not become a “singular state” such as noise. However, when the singular state continues for a predetermined time or more, it is necessary to confirm again by another system operation detection circuit 17 provided in the leakage current detection circuit 10.

  FIG. 3 shows a flow of diagnostic processing of the semiconductor relay diagnostic device 14, and shows the flow of processing together with FIGS. First, the motor control device 13 instructs the semiconductor relay diagnostic device 14 to start diagnostic processing. Next, when the motor control device 13 turns on the low-potential side MOSFET 21 and then turns on the high-potential side system main relay SMR1, the smoothing capacitor 15 is precharged by the voltage limited by the limiting resistor R0. .

  When the semiconductor relay diagnostic device 14 confirms the activation of the system main relay SMR1 and the MOSFET 21 in step S10, the semiconductor relay diagnostic device 14 proceeds to step S12. In step S <b> 12, the semiconductor relay diagnostic device 14 measures a temporal change in the leakage current of the leakage current detection circuit 10. Next, in step S14, a steady value, a maximum value, and a minimum value in a time change are calculated. If the steady value calculated in step S14 is less than or equal to the steady threshold value in FIG. 2, the process proceeds to step S22 and is determined to be “normal”.

  If the calculated steady value exceeds the steady threshold value, the process proceeds to step S18. If the maximum / minimum value exceeds both the maximum threshold value and the minimum threshold value in step S18, the process proceeds to step S24 as a singular state. In step S24, it is determined that the noise is present, and the detection counter n is incremented. In step S26, if the detection counter n is N times or less, the process returns to step S12 and measurement is continued. The maximum threshold value and the minimum threshold value are set around the average value of the leak current waveform.

  If it exceeds N times in step S26, the process proceeds to step S20. In step S20, when the operation state of the MOSFET 21 is compared with the state signal from the operation detection circuit 17, the operation state of the MOSFET 21 is not matched. It is determined as “failure” and ends.

  In the present embodiment, when the semiconductor relay diagnostic device 14 determines that the “singular state” is caused by noise, the process for continuing the measurement is performed. However, the present invention is not limited to this process, and the semiconductor relay diagnosis itself It is also preferable to replace with a process of masking for a predetermined time. Moreover, although the semiconductor relay diagnostic device 14 is provided in the present embodiment, it may be realized by a program of the motor control device. Furthermore, in the present embodiment, the semiconductor switch has been described as a MOSFET, but is not limited to this, and may be an IGBT (Insulated Gate Bipolar Transistor) or the like.

1 is a configuration diagram of a motor control system including a semiconductor relay diagnostic device according to an embodiment of the present invention. It is explanatory drawing explaining the change of the leakage voltage measured in the semiconductor relay diagnostic apparatus, and determination conditions. It is a flowchart figure which shows the flow of the diagnostic process of a semiconductor relay diagnostic apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Leakage current detection circuit, 11 Inverter, 12 Rotating electric machine, 13 Motor control apparatus, 14 Semiconductor relay diagnostic apparatus, 15 Smoothing capacitor, 16 Differential amplifier, 17 Operation | movement detection circuit, 18 Battery, 21 MOSFET, 100 Motor drive system.

Claims (8)

In a vehicle semiconductor relay diagnostic apparatus for diagnosing an abnormality of a semiconductor relay in which an electromagnetic relay and a semiconductor relay are provided between the inverter and the battery,
Arranged in parallel with the low potential electromagnetic relay provided between the low potential side of the battery and the low potential side of the inverter, and connected in series with the semiconductor relay between the low potential side of the battery and the low potential side of the inverter. Leakage current detection means for detecting leakage current by the voltage across the resistance element;
After the high-potential electromagnetic relay provided between the high-potential side of the battery and the high-potential side of the inverter becomes conductive, the abnormality of the semiconductor relay is diagnosed based on the time change of the detected leakage current on the low-potential side Diagnostic means to
A vehicular semiconductor relay diagnostic apparatus. The semiconductor relay diagnostic device for a vehicle according to claim 1,
Storing a time change of the leakage current detected by the leakage current detection means, and having a calculation means for calculating a steady value and a maximum / minimum value based on the stored leakage current,
A diagnostic device for a semiconductor relay for a vehicle, which uses a leakage current after the high-potential electromagnetic relay is turned on, and determines that it is in a normal state when the calculated steady value is equal to or less than a predetermined value. The vehicular semiconductor relay diagnostic apparatus according to claim 2, further comprising:
The vehicle semiconductor relay diagnostic device for determining a disturbance state when the measured steady value exceeds a predetermined value and the calculated steady value and the change amount of the maximum and minimum values exceed a predetermined value. The vehicular semiconductor relay diagnostic apparatus according to claim 3, further comprising:
The diagnostic means determines the failure state when the measured steady value exceeds a predetermined value and the calculated steady value and the change amount of the maximum and minimum values are equal to or less than the predetermined value. . In the diagnostic method of the semiconductor relay diagnostic device for vehicles, in which an electromagnetic relay and a semiconductor relay are provided between the inverter and the battery, and the abnormality of the semiconductor relay is diagnosed,
Arranged in parallel with the low potential electromagnetic relay provided between the low potential side of the battery and the low potential side of the inverter, and connected in series with the semiconductor relay between the low potential side of the battery and the low potential side of the inverter. A leakage current detection step of detecting a leakage current by the voltage across the resistance element;
After the high-potential electromagnetic relay provided between the high-potential side of the battery and the high-potential side of the inverter becomes conductive, the abnormality of the semiconductor relay is diagnosed based on the time change of the detected leakage current on the low-potential side Diagnostic process to
A diagnostic method for a semiconductor relay diagnostic device for vehicles, comprising: In the diagnostic method of the semiconductor relay diagnostic device for vehicles according to claim 5,
Storing a time change of the leakage current detected by the leakage current detecting means, and calculating a steady value and a maximum / minimum value based on the stored leakage current,
The diagnostic step uses the leakage current after the high-potential electromagnetic relay is turned on, and when the calculated steady-state value is equal to or less than a predetermined value, the diagnostic method for the vehicle-use semiconductor relay diagnostic device determines that the vehicle is in a normal state . In the diagnostic method of the semiconductor relay diagnostic device for vehicles according to claim 6, further,
In the diagnosis step, when the measured steady-state value exceeds a predetermined value and the calculated steady-state value and the change amount of the maximum and minimum values exceed the predetermined value, the diagnosis of the vehicle semiconductor relay diagnostic device for determining a disturbance state Method. In the diagnostic method of the semiconductor relay diagnostic device for vehicles according to claim 7, further,
In the diagnosis step, when the measured steady value exceeds a predetermined value and the calculated steady value and the change amount of the maximum / minimum value are equal to or smaller than the predetermined value, the vehicle semiconductor relay diagnostic device for determining a failure state Diagnosis method.

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