JP5375737B2 - Discharge control device for power conversion system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the following problem: complete control of completely discharging a capacitor 16 connected with an input terminal of an inverter IV connected with a main machine (a motor generator 10) cannot be ensured when a vehicle has a collision. <P>SOLUTION: A series regulator 40 steps down a voltage of a capacitor 16 and outputs the stepped-down voltage to a drive unit DU of a U-phase lower arm. A flyback converter FBd for discharge control outputs electric power to a drive unit DU of a U-phase upper arm with an output of the series regulator 40 as an input. When a collision is detected, a photocoupler 54 is turned off, so that the series regulator 40 is turned on to start discharge control. Also, diagnosis of whether or not there is abnormal discharge control is implemented with a flyback converter FBn for normal use as a power supply when the capacitor 16 has no charges. <P>COPYRIGHT: (C)2012,JPO&amp;INPIT

Description

  The present invention includes a power conversion circuit that includes a series connection body of a high-potential side switching element and a low-potential side switching element, and converts the power of a DC power source into a predetermined power, an output terminal of the power conversion circuit, and the DC power source The present invention is applied to a power conversion system including a capacitor interposed therebetween, and an open / close unit that opens and closes an electric path between the power conversion circuit and the capacitor and the DC power source, and the open / close unit is opened. Discharge control means for controlling discharge of the charging voltage of the capacitor below a specified voltage by performing a process of short-circuiting both electrodes of the capacitor by operating the switching element on the high potential side and the switching element on the low potential side It is related with the discharge control apparatus of a power conversion system provided with.

  As this type of discharge control device, for example, as shown in Patent Document 1 below, the switching element on the high potential side and the switching element on the low potential side of the inverter are simultaneously turned on, so that the input terminal of the inverter There has also been proposed one in which both electrodes of a connected capacitor are short-circuited to discharge the capacitor. In this control device, in order to avoid an excessive increase in current flowing when both electrodes of the capacitor are short-circuited, the voltage at the gate of the IGBT, which is a switching element, is reduced at the time of discharge control compared to the normal time. Yes.

JP 2009-232620 A

  By the way, when the switching element is operated in a mode different from the normal time at the time of discharge control as described above, the function of performing the discharge control is not used at the normal time. For this reason, being able to drive the inverter during normal time does not mean that the discharge control can be performed normally. For this reason, when a request to perform discharge control occurs, there is a possibility that the discharge control cannot actually be performed.

  The present invention has been made to solve the above-described problems, and its object is to operate a power conversion circuit to prevent abnormalities in discharge control by a discharge control means that controls discharge of a capacitor to a specified voltage or less. An object of the present invention is to provide a discharge control device for a power conversion system capable of appropriately diagnosing the presence or absence.

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

  The invention according to claim 1 is a power conversion circuit including a series connection body of a high-potential side switching element and a low-potential side switching element, which converts the power of the DC power source into a predetermined power, and an output terminal of the power conversion circuit And a capacitor interposed between the DC power supplies, and an open / close means for opening and closing an electric path between the power conversion circuit and the capacitor and the DC power supply, wherein the open / close means is in an open state. A discharge control device for a power conversion system comprising discharge control means for controlling the charge voltage of the capacitor to a specified voltage or less by operating the switching element on the high potential side and the switching element on the low potential side In the above, simulation means for simulating the operation of the switching element by the discharge control means, and simulation by the simulation means An abnormality diagnosing means for diagnosing the presence or absence of abnormality in the discharge control by the discharge control means based on the operation of the switching element to be simulated when the process is performed, and the high potential side switching element And the first power source, which is the power source of the drive circuit when the switching element on the low potential side is operated by the discharge control means, outputs the charging energy of the capacitor, and is simulated by the simulation means The second power source, which is the power source of the drive circuit when the operation is performed, outputs energy different from the charging energy of the capacitor.

  In the above invention, by providing the simulation means and the abnormality diagnosis means, it is possible to diagnose the presence or absence of abnormality in the discharge control without relying on detection of whether or not the capacitor is actually discharged. Further, in the above invention, the power supply of the drive circuit when the simulation process is performed by the simulation means is a second power supply different from the first power supply, so that the charging energy of the capacitor is insufficient. However, it is possible to perform a simulation process and thus diagnose whether there is an abnormality.

  According to a second aspect of the present invention, in the first aspect of the present invention, the power conversion circuit constitutes an in-vehicle high voltage system insulated from the in-vehicle low voltage system, and the second power source is connected to the low voltage system. An insulating converter having a secondary side is provided.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the second power source is a power source of the drive circuit during the process of converting to the predetermined.

  In the above invention, it is possible to avoid preparing a new power supply for the drive circuit for abnormality diagnosis.

  According to a fourth aspect of the present invention, in the first aspect of the present invention, between the first power source and the drive circuit, the first power source side is moved to the drive circuit side. Rectifying means having a forward direction as a forward direction is provided, and a rectifying means having a forward direction as a forward direction from the second power supply side to the drive circuit side is provided between the second power supply and the drive circuit. Is provided.

  In the above invention, since the rectifying means is provided, the driving circuit is used both when the process of simulating by the simulating means and at the time of discharging control by the discharging control means without changing the connection between the power source and the driving circuit. Can be supplied with electrical energy.

  According to a fifth aspect of the invention, there is provided the switching means according to any one of the first to third aspects, wherein the switching means switches between the first power source and the second power source as the power source of the drive circuit. It is characterized by that.

  In the above invention, since the switching means is provided, the electric energy can be supplied to the drive circuit both when the simulation process is performed by the simulation means and during the discharge control by the discharge control means.

  The invention according to claim 6 is the invention according to any one of claims 1 to 5, wherein the discharge control means turns on both the switching element on the high potential side and the switching element on the low potential side. Thus, a process of short-circuiting both electrodes of the capacitor is performed.

  According to a seventh aspect of the invention, in the sixth aspect of the invention, the high-potential side switching element and the low-potential side switching element are voltage-controlled switching elements, and the discharge control means includes the high potential side switching element. Voltage applied to the conduction control terminal of the at least one switching element so that the current in the non-saturation region of at least one of the potential side switching element and the low potential side switching element is smaller than that during the process of converting to the predetermined value. The abnormality diagnosing means diagnoses the presence or absence of the abnormality based on a value of a voltage applied to a conduction control terminal of the at least one switching element.

  In the above invention, since the voltage applied to the conduction control terminal during the discharge control is different from that during the process of converting to the predetermined value, the discharge control is ensured even when no abnormality occurs during the process of converting to the predetermined value. There is no guarantee that it can be performed. In this respect, in the above invention, it is confirmed whether or not the operation at the time of discharge control can be realized by using the detected value of the voltage of the conduction control terminal when the at least one switching element is turned on by the simulated process. Can do.

  The invention according to claim 8 is the invention according to claim 6 or 7, wherein the high-potential side switching element and the low-potential side switching element are voltage-controlled switching elements, and the discharge control means includes: The switching of either one of the high-potential side switching element and the low-potential side switching element so that the current in one of the non-saturation regions is smaller than the other one. The voltage applied to the conduction control terminal of the element is set, and the discharge control means switches the switching state of one of the two while the other is in the on state. A process of generating the short-circuited state of both electrodes a plurality of times by repeating one of the ON state and the OFF state a plurality of times And than, the abnormality diagnosis means may be assessed for the presence or absence of the abnormality at least one of the length on the basis of whether the allowable range of the ON period and OFF period of the one of the switching elements.

  The on period in the discharge control period is set to a time interval such that the amount of heat generated by the switching element does not become excessively large. In this regard, if it is confirmed whether or not the length of the on-period is within the allowable range, it is possible to confirm whether or not the operation according to this setting is performed.

  On the other hand, the off period in the discharge control period is set so that the temperature rise rate of the switching element does not become excessively large. In this regard, if it is ascertained whether or not the length of the off period is within an allowable range, it is possible to grasp whether or not the rate of temperature increase of the switching element is excessively increased by the discharge control.

  The invention according to claim 9 is the invention according to any one of claims 1 to 8, further comprising determination means for determining whether or not an abnormality has occurred in a member on which the power conversion system is mounted, and the discharge The control means is a process of short-circuiting both electrodes of the capacitor by turning on both the high-potential side switching element and the low-potential side switching element when the determination means determines that an abnormality has occurred. A normal discharge that discharges the capacitor without performing the short-circuiting process when the opening / closing means is in an open state and it is not determined that the abnormality has occurred. The apparatus further comprises means.

  In the above invention, since the abnormal discharge control means is not used until it is determined that an abnormality has occurred, it is particularly desirable to confirm whether or not this actually operates in the event of an abnormality. For this reason, the utility value of the simulation means and the abnormality diagnosis means is particularly great.

1 is a system configuration diagram according to a first embodiment. FIG. A circuit diagram showing composition of drive unit DU concerning the embodiment. The time chart which shows discharge control at the time of abnormality concerning the embodiment. The figure which shows the characteristic of IGBT. The flowchart which shows the procedure of the normal time discharge process concerning the said embodiment. The flowchart which shows the process sequence of discharge control at the time of abnormality concerning the embodiment. The flowchart which shows the procedure of the diagnostic process of the presence or absence of abnormality of the abnormal time discharge control concerning the embodiment. The circuit diagram which shows the structure of the drive unit DU concerning 2nd Embodiment. The system block diagram concerning the modification of the said embodiment.

<First Embodiment>
Hereinafter, a first embodiment in which a discharge control device of a power conversion system according to the present invention is applied to a hybrid vehicle will be described with reference to the drawings.

  FIG. 1 shows the system configuration of this embodiment. The illustrated motor generator 10 is an in-vehicle main machine and is mechanically coupled to drive wheels. Motor generator 10 is connected to high-voltage battery 12 via inverter IV and a parallel connection body of relay SMR2 and resistor 14 and relay SMR1. Here, the high voltage battery 12 has a terminal voltage of, for example, a high voltage of 100 V or higher. Further, among the input terminals of the inverter IV, a capacitor 16 is connected in parallel to the inverter IV side of the relays SMR1 and SMR2.

  The inverter IV is configured by connecting three series connection bodies of a high-potential side switching element Swp and a low-potential side switching element Swn as power elements in parallel. The connection points of the high-potential side switching element Swp and the low-potential side switching element Swn are connected to the respective phases of the motor generator 10.

  Between the input / output terminals (between the collector and the emitter) of the switching element Swp on the high potential side and the switching element Swn on the low potential side, the free wheel diode FDp on the high potential side and the free wheel diode FDn on the low potential side are connected. The cathode and anode are connected. The switching elements Swp and Swn are both formed of insulated gate bipolar transistors (IGBT). The switching elements Swp and Swn include a sense terminal St that outputs a minute current having a correlation with a current flowing between the input terminal and the output terminal.

  The minute current output from the sense terminal St flows through the shunt resistor 19, and the voltage drop due to this flows in the drive unit DU for driving the switching element Sw # (# = p, n) (only U phase is shown in the figure). Is taken in. The drive unit DU forcibly turns off the switching element Sw # when it is determined that the current flowing between the input terminal and the output terminal of the switching element Sw # is equal to or greater than the threshold current Ith based on the voltage drop amount in the shunt resistor 19. It has a function to make a state.

  On the other hand, the control device 30 is an electronic control device that uses the low-voltage battery 20 as a power source. The control device 30 operates the inverter IV in order to control the control amount of the motor generator 10 as a control target. Specifically, the control device 30 operates based on detection values of various sensors (not shown) and the like, operation signals gup, gvp, gwp for operating the switching elements Swp for the U phase, the V phase, and the W phase of the inverter IV, Operation signals gun, gvn, and gwn for operating the switching element Swn are generated and output. Thereby, the switching elements Swp and Swn are operated by the control device 30 via the drive unit DU connected to their conduction control terminals (gates).

  Incidentally, the high voltage system including the inverter IV and the low voltage system including the control device 30 are insulated by an insulating means such as a photocoupler (not shown), and the operation signal g * # (* = u, v, w , # = P, n) is output to the high voltage system via the insulating means.

  The drive unit DU uses a normal flyback converter FBn as a power source. The normal flyback converter FBn is an isolated converter for supplying the power of the low voltage battery 20 to the upper arm and the lower arm. That is, the energy of the low-voltage battery 20 is stored in the primary coil 32a of the transformer 32 by closing the power switching element 34. At this time, in the secondary coil 32b, the diode 36 prevents the current from flowing. In contrast, when the power switching element 34 is opened, a current flows through the secondary coil 32b, and the normal capacitor 38 is charged. The charging energy of the normal capacitor 38 becomes the energy consumption of the drive unit DU. Although FIG. 1 only shows that the normal-time flyback converter FBn serves as a power source for the U-phase upper and lower arm drive units DU, the power source for the V-phase and W-phase drive units DU is actually used. It is also. For this reason, the number of secondary side coils 32b of the transformer 32 is actually six. However, considering that the potential of the lower arm is common, the secondary side coils for the lower arm may be shared, and in this case, the number of secondary side coils 32b is four.

  By the way, the control device 30 detects the collision of the vehicle based on the detection value of the acceleration detecting means (G sensor 22) that detects the acceleration based on the force acting on itself, and forcibly sets the capacitor 16 when the collision is detected. It has a function of performing a process of discharging electrically. During this abnormal discharge control, an abnormality has occurred in the vehicle, and therefore the normal flyback converter FBn may not function as a power source for the drive unit DU. In this embodiment, therefore, a series regulator 40 that steps down the voltage of the capacitor 16 and a discharge flyback converter FBd that uses the output of the series regulator 40 as inputs are separately provided as a power source for the drive unit DU during discharge control during abnormal conditions. Yes.

  The series regulator 40 includes a series connection body of a plurality of (herein, four examples) resistors 44 and a Zener diode 48, which are connected in parallel to the capacitor 16. A plurality of N-channel MOS field effect transistors (switching elements 42) are connected in parallel to the resistor 44. Here, the highest potential resistor 44 is connected between the input terminal of the highest potential switching element 42 and the conduction control terminal, and the conduction control terminals of the intermediate switching element 42 are connected by the resistor 44. ing. Furthermore, the conduction control terminal and the output terminal of the switching element 42 having the lowest potential are connected by a resistor 46.

  The zener diode 48 is connected in parallel with the input terminal and output terminal of the phototransistor on the secondary side of the photocoupler 54. Accordingly, when the photocoupler 54 is turned on, the Zener diode 48 is turned off, and the switching element 42 is turned off. On the other hand, when the photocoupler 54 is turned off, the Zener diode 48 is turned on, and the output voltage of the series regulator 40 rises to the breakdown voltage of the Zener diode 48. When the output current of the series regulator 40 becomes larger than zero, a current flows through the resistor 46, and the switching element 42 having the lowest potential is turned on by the voltage drop. At this time, the resistor 44 functions so that the voltage between the input terminal of the switching element 42 and the conduction control terminal other than the lowest potential is the voltage drop amount of the resistor 46. For this reason, all the switching elements 42 are switched to the on state. At this time, these switching elements 42 operate in a non-saturated region, and the voltage between the output terminal and the input terminal of each switching element 42 is a value obtained by subtracting the breakdown voltage of the Zener diode 48 from the voltage of the capacitor 16. The value is approximately divided by the number of.

  The photodiode on the primary side of the photocoupler 54 is turned on when the abnormal-time discharge command dis output by the control device 30 becomes logic “H”. The abnormal-time discharge command dis is set to logic “H” as long as no collision occurs in a state where the control device 30 is activated. This is a setting for turning on the series regulator 40 even when the control device 30 cannot operate the photocoupler 54 due to a collision.

  On the other hand, the discharge flyback converter FBd stores the output energy of the series regulator 40 in the primary side coil 60a of the transformer 60 when the power switching element 64 is closed. At this time, the current flow is blocked by the diode 66 in the secondary coil 60 b of the transformer 60. Then, when the power supply switching element 64 is opened, a current is output to the discharging capacitor 68 via the diode 66. It should be noted that the output voltage of the discharge flyback converter FBd (the output voltage of the discharge capacitor 68) is approximately equal to the output voltage of the series regulator 40. The duty ratio is manipulated by the lower arm drive unit DU. This process is performed with the output voltage of the series regulator 40 being applied to the drive unit DU of the U-phase lower arm as a trigger.

  FIG. 2 shows a configuration of a drive circuit unit for turning on / off switching element Sw # in particular among drive units DU of U-phase switching element Sw #.

  As shown in the figure, in each drive unit DU of the upper and lower arms of the U phase, the voltage of the normal capacitor 38 is controlled to conduct the switching element Sw # via the charging switching element 70 and the gate resistor 72. Applied to terminal (gate). The gate of the switching element Sw # is connected to the output terminal (emitter) of the switching element via the gate resistor 72 and the discharging switching element 74, and this becomes a gate discharge path. The charging switching element 70 and the discharging switching element 74 are turned on / off by the normal-time drive control unit 76 according to the operation signal gu #. As a result, the switching element Sw # is turned on / off by the normal-time drive control unit 76.

  The U-phase drive unit DU further has a discharge execution condition that the logical product of the abnormal-time discharge command dis being logic “L” and the normal-time flyback converter FBn being off is true. A dedicated circuit for turning on / off the switching element Sw # is provided.

  Here, in U-phase lower arm drive unit DU, the output voltage of series regulator 40 (the output voltage of diode 52) is applied to the gate of switching element Swn via charging switching element 82 and gate resistor 72. . The gate is connected to the emitter of the switching element Swn via the gate resistor 72 and the discharge switching element 84. On the other hand, the positive-polarity terminal of the normal-time capacitor 38 and the anode side of the diode 52 are connected to the abnormal-time drive control unit 86, and when the discharge execution condition is satisfied, the charging switching element 80 and discharge The switching element 84 is turned on.

  On the other hand, the voltage drop amount of the shunt resistor 19 due to the minute current output from the sense terminal St of the switching element Swn on the low potential side is applied to the non-inverting input terminal of the comparator 92 via the peak hold 90. An output signal (carrier) of an oscillator 94 that outputs a signal having a predetermined frequency is applied to the inverting input terminal of the comparator 92. As a result, the comparator 92 outputs a signal that is logic “H” when the voltage drop amount is larger than the carrier.

  On the other hand, in the drive unit DU of the U-phase upper arm, in addition to the charging switching element 82, the discharging switching element 84, and the abnormal time drive control unit 86, there is a gap between the charging switching element 82 and the discharging capacitor 68. In addition, a diode 96, a switching element 98, and a regulator 104 that steps down the voltage VH of the discharging capacitor 68 are provided. Here, the switching element 98 is turned on when the determination unit 100 taking in the voltage on the anode side of the diode 96 and the positive voltage of the normal-time capacitor 38 determines that the discharge execution condition is satisfied.

  On the other hand, the output signal of the comparator 92 is output to the primary side (photodiode) of the photocoupler 102 as the heat generation control operation amount Mh. The output terminal on the secondary side (phototransistor) of the photocoupler 102 is connected to the emitter of the switching element Swp, and the input terminal is connected to the switching element 98 via a resistor. The output signal of the photocoupler 102 is input to the upper arm abnormal time drive control unit 86. Thereby, the switching element Swp on the high potential side is turned on while the discharge execution condition is satisfied and the photocoupler 102 is turned off.

  In the vicinity of the switching element Swp on the high potential side, a temperature sensitive diode SD for detecting the temperature is provided. Specifically, the cathode side of the temperature sensitive diode SD is connected to the emitter of the switching element Swp, and the anode side is connected to the output terminal of the constant current circuit 106 using the discharging capacitor 68 as a power feeding means. Then, the voltage on the anode side is taken into the voltage comparison circuit 108, and the output signal of the voltage comparison circuit 108 is taken into the regulator 104. The regulator 104 variably sets the output voltage VL (<VH) according to the temperature detected by the temperature sensitive diode SD. Incidentally, the output voltage of the temperature sensitive diode SD and the temperature of the detection target have a negative correlation.

  FIG. 3 shows an aspect of discharge control based on the abnormal-time discharge command dis. Specifically, FIG. 3 (a) shows the transition of the abnormal-time discharge command dis, and FIG. 3 (b) shows the transition of the output signal (one-dot chain line) of the peak hold 90 and the carrier output by the oscillator 94. FIG. 3C shows the transition of the state of the U-phase high potential side switching element Swp, and FIG. 3D shows the transition of the state of the U-phase low potential side switching element Swn. As illustrated, in this embodiment, the switching element Swp on the high potential side is periodically switched between the on state and the off state while the switching element Swn on the low potential side of the U phase is maintained in the on state. As a result, there is a period in which both the high-potential side switching element Swp and the low-potential side switching element Swn are turned on at the same time. During this period, the two electrodes of the capacitor 16 are connected via the switching elements Swp and Swn. As a result, the capacitor 16 is discharged.

  At this time, because of the configuration of the drive unit DU shown in FIG. 2, the gate applied voltage of the switching element Swp on the high potential side is on the low potential side as shown in FIGS. 3 (e) and 3 (f). It becomes lower than the gate applied voltage of the switching element Swn. Here, FIG. 3E shows the transition of the gate-emitter voltage Vge of the high-potential side switching element Swp, and FIG. 3F shows the transition of the gate-emitter voltage Vge of the low-potential side switching element Swn. Shows the transition.

  According to such a configuration, the switching element Swp on the high potential side is driven in the non-saturation region, and the switching element Swn on the low potential side is driven in the saturation region. Here, as shown in FIG. 4, the saturation region is a region where the voltage between the input terminal and the output terminal of the switching element (collector-emitter voltage Vce) increases in accordance with the output current (collector current Ic). is there. On the other hand, the non-saturated region is a region where the collector-emitter voltage Vce increases without increasing the collector current. The collector current Ic that becomes the non-saturated region increases as the gate applied voltage (gate-emitter voltage Vge) increases.

  For this reason, by lowering the gate applied voltage of the switching element Swp on the high potential side than the switching element Swn on the low potential side, the switching element Swp on the high potential side is less saturated than the switching element Swn on the low potential side. The current in the region is reduced. As a result, the current flowing through the switching element Swp on the high potential side and the switching element Swn on the low potential side by discharge control is limited to the current in the non-saturated region of the switching element Swp on the high potential side. Note that it is desirable that the current in the non-saturation region of the switching element Swp on the high potential side is set to be less than the threshold current Ith defined by the drive unit DU.

  In particular, in this embodiment, the temperature of the switching element Swp on the high potential side is set as a control amount, which is detected by the temperature sensitive diode SD, and feedback control is performed so that the detected value does not become excessively high. Here, the feedback control amount is set to the temperature of the switching element Swp on the high potential side because the majority of the heat generated by the discharge control is due to the switching element Swp on the high potential side driven in the non-saturation region. It is in view of becoming. As shown in FIG. 2, the voltage applied to the gate of the switching element Swp is adopted as the operation amount of the temperature feedback control in this embodiment. As a result, as shown in FIG. 3E, when the output voltage of the temperature sensitive diode SD decreases (when the temperature detected by the temperature sensitive diode SD increases), the applied voltage is decreased. As a result, the current in the non-saturated region of the switching element Swp on the high potential side can be reduced, so that the discharge current can be reduced.

  In the present embodiment, the discharge control is further performed in the manner shown in FIG. 3, so that the higher the value of the output signal of the peak hold 90 (the larger the discharge current), the higher the switching element Swp on the higher potential side. Control is performed so that the time ratio of the ON time to one ON / OFF cycle becomes small. As a result, when the discharge current is large, control is performed to reduce the amount of heat generated within a unit time (for example, one cycle of the carrier), thereby avoiding an excessive increase in the amount of heat generated per unit time. it can.

  The discharge control is performed at the time of a vehicle collision or the like. In the present embodiment, the inverter IV is operated even when the vehicle is stopped during normal times and the relay SMR1 is switched to the open state. Discharge control is performed. However, the discharge control at this time is executed by passing a reactive current to the motor generator 10. Thereby, the capacitor 16 can be discharged more rapidly than the discharge of the capacitor 16 by the discharge resistor 18.

  FIG. 5 shows a procedure for normal discharge control in the present embodiment. This process is repeatedly executed by the control device 30 at a predetermined cycle, for example.

  In this series of processes, first, in step S10, it is determined whether or not the relay SMR1 is switched from the closed state to the open state by turning off the start switch of the vehicle. Here, the vehicle activation switch is a means for allowing the user to activate the vehicle. The activation switch is not necessarily required to be mechanically operated. For example, even if the activation switch is a wireless device carried by the user and is close to the vehicle, the activation permission signal can be received by the vehicle side. Good. When an affirmative determination is made in step S10, in step S12, the operation signal g * # is set so as to flow a reactive current, and is output to each switching element Sw #. Here, for example, when the motor generator 10 is IPMSM or SPM, the operation signal g * # may be set so that the q-axis current is zero and the absolute value of the d-axis current is larger than zero.

  When the process of step S12 is completed or when a negative determination is made in step S10, this series of processes is temporarily terminated.

  FIG. 6 shows a processing procedure of abnormal discharge control in the present embodiment. This process is repeatedly executed by the control device 30 at a predetermined cycle, for example.

  In this series of processes, first, in step S20, a detection value of the G sensor 22 is input. In a succeeding step S22, it is determined whether or not the vehicle has collided based on the input detection value. Here, if the detected acceleration is equal to or greater than a predetermined value, it may be determined that a collision has occurred. If it is determined that the vehicle has collided, the relays SMR1 and SMR2 are opened in step S24. Further, in step S26, the abnormal-time discharge command dis is set to logic "L" and the normal time flyback converter FBn is turned off. When the process of step S26 is completed or when a negative determination is made in step S22, this series of processes is temporarily terminated.

  By the way, the abnormal discharge control is not used unless an abnormal situation such as a vehicle collision occurs. Whether or not the abnormal-time discharge control is surely performed in an abnormal state cannot be determined by whether or not the motor generator 10 can be normally controlled. This is because the power supply of the drive unit DU at the time of abnormal discharge control and the power supply of the drive unit DU at normal time are different, or the operation signals gup, gun of the switching elements Swp, Swn at normal time and at the time of discharge control at abnormal time This is because it is a different signal.

  Therefore, in the present embodiment, the abnormal discharge control is actually performed by using the diagnosis units 120 and 122 shown in FIG. Check if it is feasible. Each of these diagnosis units 120 and 122 determines whether or not the same operation as the abnormal-time discharge control is possible based on the voltage of the gate of the switching element Sw #. This diagnosis is performed by outputting an abnormality diagnosis command Dg from the control device 30. That is, when the abnormality diagnosis command Dg is taken into the abnormality-time drive control unit 86 of the lower arm, it is possible to simulate the abnormality-time discharge control operation of the switching element Swn. Further, at this time, the abnormality diagnosis command Dg is taken into the determination unit 100 of the upper arm, so that the operation of the discharge control at the time of abnormality of the switching element Swp can be simulated.

  However, as described above, since the abnormal discharge control is performed using the series regulator 40 as a power supply source, there is a possibility that electric energy cannot be supplied to the drive unit DU at the time of diagnosis. In view of this point, in the present embodiment, as shown in FIG. 2, the power of the normal-time capacitor 38 of the lower arm is supplied to the abnormal-time drive control unit 86, the charging switching element 82, and the like via the diode 130. The power of the normal-time capacitor 38 of the upper arm is supplied to the abnormal-time drive control unit 86, the charging switching element 82, and the like via the diode 132.

  The diode 130 has a function of preventing the output of the series regulator 40 from flowing into the normal capacitor 38, and the diode 132 allows the charging energy of the discharging capacitor 68 to flow into the normal capacitor 38. It has a function to prevent. The diode 96 has a function of preventing the charging energy of the normal capacitor 38 from flowing into the discharging capacitor 68.

  FIG. 7 shows a procedure of processing for diagnosing the presence or absence of abnormality in the abnormal-time discharge control according to the present embodiment. This process is repeatedly executed by the control device 30 at a predetermined cycle, for example.

  In this series of processes, first, in step S30, it is determined whether or not the start switch has been switched to the on state. This process is for determining whether or not the diagnosis execution condition is satisfied. If it is determined that the start switch has been switched to the on state, the diagnosis condition is satisfied and an abnormality diagnosis command Dg is output in step S32. In the subsequent step S34, a timer timing operation for counting the output continuation time of the abnormality diagnosis command Dg is started. If normality is not detected until the timer becomes equal to or greater than the threshold time Tth (NO in step S36 and YES in step S44), in step S46, the user is notified of the abnormality and is recognized by the user.

  On the other hand, when normality is detected before the threshold time Tth has elapsed (step S36: YES), the charge of the high-voltage battery 12 is closed via the high-resistance electrical path by closing the relay SMR2 in step S38. Is charged into the capacitor 16. When a predetermined time has elapsed (step S40: YES), the relay SMR2 is switched to the open state and the relay SMR1 is switched to the closed state. As a result, the high voltage battery 12 and the capacitor 16 are connected by the low resistance electric path. It is assumed that the capacitor 16 is charged to a charging voltage that is assumed to prevent an excessively large current from flowing through the capacitor 16 even if the high voltage battery 12 and the capacitor 16 are connected by a low resistance electric path during the predetermined time. Set to

  In addition, when the process of said step S42, S46 is completed, or when negative determination is made in step S30, this series of processes is once complete | finished. Incidentally, the determination of “normal” in step S36 is that the diagnosis unit 120 determines that the gate application voltage of the switching element Swp is within the allowable range (the difference from the voltage VL is within the allowable range). The diagnostic unit 122 determines that the switching element Swn is turned on. In the case of the configuration shown in FIG. 2, it cannot be diagnosed whether the switching element Swp repeats the on / off operation. However, for example, as shown by a broken line in FIG. 2, whether or not the on / off operation is repeated can be diagnosed by setting a default value in the peak hold 90 according to the diagnostic signal Dg. In this case, the determination of “normal” in step S36 further includes the determination that the ON time and OFF time of the switching element Swp are within the allowable range.

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

  (1) A drive unit for performing discharge control during an abnormality using a series regulator 40 for stepping down the voltage of the capacitor 16 and a discharge flyback converter FBd having the output as an input as a power source of the drive unit DU and diagnosing the presence or absence of the abnormality The power source of the DU is a normal flyback converter FBn. Thereby, even if the capacitor 16 has no electric charge, it can be diagnosed whether there is an abnormality.

  (2) When the series regulator 40 (discharge capacitor 68) and the normal capacitor 38 are connected to the means used for the abnormal discharge control in the drive unit DU, the diodes 52, 96, 130, and 132 are interposed. . As a result, electric energy can be supplied to the means used for the abnormal discharge control both during the diagnosis process and during the abnormal discharge control.

  (3) The discharge control during abnormality is performed by reducing the gate applied voltage of the switching element Swp on the high potential side to be lower than the gate applied voltage of the switching element Swn on the low potential side, and diagnosing the presence or absence of abnormality. This was performed based on the value of the gate applied voltage. Thereby, it can be confirmed whether the operation | movement at the time of discharge control is realizable.

(4) Short-circuit state of both electrodes of the capacitor 16 by repeating on-off and off-state of the high-potential side switching element Swp a plurality of times while maintaining the low-potential side switching element Swn in the on-state during the abnormal discharge control. And the diagnosis of the presence or absence of abnormality was performed based on whether the lengths of the on period and the off period of the switching element Swp are within the allowable range. As a result, it is possible to confirm whether or not the amount of heat generated by the switching element and the temperature rise rate are not excessively increased during the abnormal discharge control.
<Second Embodiment>
Hereinafter, the second embodiment will be described with reference to the drawings with a focus on differences from the first embodiment.

  FIG. 8 shows a configuration of a drive circuit unit for turning on / off switching element Sw # in particular among drive units DU of U-phase switching element Sw #. In FIG. 8, members corresponding to those shown in FIG. 2 are given the same reference numerals for convenience.

  As shown in the figure, in the present embodiment, in the U-phase upper arm, either the positive electrode of the normal capacitor 38 or the positive electrode of the discharge capacitor 68 is selectively used as a member for abnormal discharge control. A switching circuit 140 to be connected is provided. In addition, the lower arm of the U phase includes a switching circuit 142 that selectively connects either the positive electrode of the normal capacitor 38 or the cathode of the diode 52 to a member used for abnormal discharge control. Here, the switching circuit 140 normally connects the discharging capacitor 68 to a member used for abnormal discharge control, and the normal capacitor 38 is abnormal only when the abnormal diagnosis command Dg is input. It connects to the member used for hourly discharge control. In addition, the switching circuit 142 normally connects the cathode side of the diode 52 to a member used for abnormal discharge control, and the normal capacitor 38 is abnormal only when the abnormal diagnosis command Dg is input. It connects to the member used for hourly discharge control.

  According to the present embodiment described above, in addition to the effects (1), (3), and (4) of the first embodiment, the following effects can be obtained.

(5) The switching circuits 140 and 142 for selecting either the series regulator 40 (discharge capacitor 68) or the normal capacitor 38 are provided. As a result, electric energy can be supplied to the means for performing the abnormal discharge control both in the diagnosis process and in the discharge control.
<Other embodiments>
Each of the above embodiments may be modified as follows.
“Discharge execution conditions”
The discharge execution conditions are not limited to those exemplified in the above embodiments. For example, only the series regulator 40 and the discharge flyback converter FBd output a voltage may be the discharge execution condition.
About abnormal discharge control means
As the discharge control means at the time of abnormality, the short-circuit state of both electrodes of the capacitor 16 is achieved by repeating the ON state and the OFF state of the high potential side switching element Swp a plurality of times while maintaining the low potential side switching element Swn in the ON state. The present invention is not limited to processing that generates multiple times. For example, a process of generating a short circuit state of both electrodes of the capacitor 16 a plurality of times by repeating the ON state and the OFF state of the low potential side switching element Swn a plurality of times while maintaining the switching element Swp on the high potential side in an on state. It may be what you do. However, even in this case, the gate applied voltage on the side where the ON state and the OFF state are repeated a plurality of times is set lower, and the operation is performed in the non-saturated region. Further, for example, a process of generating a short-circuit state of both electrodes of the capacitor 16 a plurality of times by repeating a simultaneous on state and a simultaneous off state of the high potential side switching element Swp and the low potential side switching element Swn a plurality of times. It may be what you do. Again, the gate applied voltage is adjusted so that one of the high-potential side switching element Swp and the low-potential side switching element Swn is operated in the non-saturation region. However, at this time, it is desirable to switch the switching state of the operation in the non-saturation region while the operation in the saturation region is in the on state. Further, both the high-potential side switching element Swp and the low-potential side switching element Swn may be turned on only once in the discharge control period. Again, the gate applied voltage is adjusted so that one of the high-potential side switching element Swp and the low-potential side switching element Swn is operated in the non-saturation region.

  Further, the discharge control is not limited to using only the combination of the switching element Swp on the high potential side and the switching element Swn on the low potential side that applies a voltage to one phase of the motor generator 10. For example, the switching element Swp on the high potential side and the switching element Swn on the low potential side of each phase may be switched so as to be sequentially turned on.

  In these controls, it is not necessary to perform temperature feedback control or heat generation control based on the current amount. In this case, even if the ON state and the OFF state of either the high potential side switching element Swp or the low potential side switching element Swn are repeated a plurality of times, the ON period or the OFF period is within an allowable range. The diagnosis of whether or not can be performed more easily.

  Further, the abnormal-time discharge control means is not limited to one that performs discharge control by turning on both the high-potential side switching element Swp and the low-potential side switching element Swn. For example, a means for causing a reactive current to flow through the motor generator 10 may be used.

Note that the discharge control performed by turning on both the high-potential side switching element Swp and the low-potential side switching element Swn is performed every time the relay SMR1 is switched to the open state, not limited to an abnormal time. May be.
"About simulation means"
The simulation means is not limited to one that actually short-circuits both ends of the capacitor 16 by turning on both the high-potential side switching element Swp and the low-potential side switching element Swn. For example, only one of the high-potential side switching element Swp and the low-potential side switching element Swn may be turned on by the abnormal-time drive control unit 86.
"Abnormality diagnosis methods"
As the abnormality diagnosis means, for the high-potential side switching element Swp, whether the gate applied voltage is within the allowable range, whether the on-time is within the allowable range, and whether the off-time is within the allowable range It is not limited to determining all of them, and it is sufficient to determine at least one of these. Further, the switching element Swn on the low potential side is not limited to determining whether or not the switching element Swn is turned on. For example, it may be determined whether or not the gate applied voltage is within an allowable range. Further, the diagnosis is not limited to both the high-potential-side switching element Swp and the low-potential-side switching element Swn, and the diagnosis may be made only on either one.

  The condition for executing the abnormality diagnosis is not limited to turning on the start switch. For example, an accessory switch for turning on power to the in-vehicle electronic device may be turned on. Note that the start switch and the accessory switch may be realized by a combination of an on operation of a dedicated switch and a brake operation. That is, the accessory switch may be turned on when the dedicated switch is turned on but the brake operation is not performed, and the activation switch may be turned on when the dedicated switch is turned on and the brake operation is performed.

The abnormality diagnosing means is not limited to one that diagnoses the presence or absence of abnormality in the high voltage system and outputs the result to the low voltage system. For example, the gate applied voltage signal may be taken into the low voltage system side (control device 30) via a transformer, and the presence or absence of an abnormality may be determined here.
"About the first power supply"
The power supply for the lower arm is not limited to the series regulator 40. For example, an insulating converter such as a flyback converter may be used. Moreover, it is not limited to an insulating converter, and may be a non-insulating converter such as a step-down chopper.

Further, the power supply of the upper arm is not limited to the discharge flyback converter FBd, but may be a forward converter, for example. Moreover, it is not restricted to an insulated converter. For example, a level shifter that shifts the potential of the series regulator 40 may be used. Further, a diode having a forward direction from the output side of the series regulator 40 to the discharging capacitor 68 side may be provided.
"About the second power supply"
The power source of the drive unit DU when the simulation is performed by the simulation unit is not limited to the normal time flyback converter FBn. For example, a series regulator that steps down the voltage of the high voltage battery 12 may be provided separately.
About the drive unit DU
The charging switching element 70 and the discharging switching element 74 and the charging switching element 80 and the discharging switching element 84 are not limited to separate members. Further, the normal time drive control unit 76 and the abnormal time drive control unit 86 are not limited to separate members.

There is no need to provide a function for forcibly turning off the switching element Sw # by exceeding the threshold current Ith.
"About DC-AC converter circuit"
As a DC / AC converter circuit (inverter IV) in which both the high-potential side switching element and the low-potential side switching element are turned on during the discharge control, the circuit between the rotating machine as the in-vehicle main unit and the high-voltage battery 12 is used. It is not limited to mediating power transfer. For example, the transfer of electric power between the high voltage battery 12 and a rotary machine other than the main machine such as a rotary machine provided in the air conditioner may be used.

Further, the DC / AC conversion circuit is not limited to the inverter IV, and may be an H bridge circuit.
"Power conversion circuit"
The power conversion circuit is not limited to the one composed only of the inverter IV. For example, as shown in FIG. 9, a reactor 150, a low-potential side switching element Swn connected in parallel to the capacitor 16 via the reactor 150, a freewheel diode FDp, a low-potential side switching element Swn, and a freewheel A boost converter CV including a capacitor 152 connected to a series connection body with the diode FDp may be connected to the input terminal of the inverter IV. In this case, the capacitor 152 and the capacitor 16 connected to the output terminal of the boost converter CV are subjected to discharge control, and the voltage of the capacitor 16 becomes the free wheel diode FDp as the voltage of the capacitor 152 of the boost converter CV decreases. It will be discharged through.

  Further, as shown in FIG. 9, when the high-side switching element Swp is connected in parallel to the freewheel diode FDp, discharge control is performed by turning on both of the pair of switching elements of the boost converter CV. Is also possible.

Even when the boost converter CV is provided, the series regulator 40 may be input with the electric energy of the capacitor 16 as an input.
(others)
The high-potential side switching element Swp and the low-potential side switching element Swn used for discharge control are not limited to IGBTs, and may be field effect transistors such as power MOS field effect transistors.

  The vehicle is not limited to a hybrid vehicle, and may be, for example, an electric vehicle in which the energy resource stored for the in-vehicle main engine is only electric energy.

  The discharge device is not limited to the one mounted on the vehicle, and may be applied to a power conversion system that converts the power of a DC power source provided in a house into AC, for example. In this case, the abnormal time may be a case where an earthquake or the like is detected.

  DESCRIPTION OF SYMBOLS 10 ... Motor generator, 12 ... High voltage battery (one embodiment of DC power supply), 16 ... Capacitor, 30 ... Control device, 40 ... Series regulator, FBd ... Discharge flyback converter, Swp ... High potential side switching element, Swn: Low-potential side switching element Swn, DU: Drive unit.

Claims (9)

A power conversion circuit having a series connection body of a switching element on the high potential side and a switching element on the low potential side and converting the power of the DC power source to a predetermined value, and interposed between the output terminal of the power conversion circuit and the DC power source The high potential is applied to a power conversion system including a capacitor, and an opening / closing unit that opens and closes an electric path between the capacitor and the capacitor and the DC power source, and the switching unit is opened. In a discharge control device of a power conversion system comprising a discharge control means for controlling the charge voltage of the capacitor to a specified voltage or less by operating the switching element on the side and the switching element on the low potential side,
Simulation means for simulating the operation of the switching element by the discharge control means;
An abnormality diagnosing means for diagnosing the presence or absence of abnormality in the discharge control by the discharge control means based on the operation of the switching element that is the target of the process to be simulated when the process simulated by the simulation means is performed;
The first power source that is the power source of the drive circuit when the high-potential side switching element and the low-potential side switching element are operated by the discharge control means outputs the charging energy of the capacitor. On the other hand, the second power source, which is the power source of the drive circuit when the simulation operation by the simulation means is performed, outputs energy different from the charging energy of the capacitor. Discharge control device. The power conversion circuit constitutes an in-vehicle high voltage system insulated from the in-vehicle low voltage system,
2. The discharge control device for a power conversion system according to claim 1, wherein the second power source includes an isolated converter including a primary side in the low-voltage system.   3. The discharge control device for a power conversion system according to claim 1, wherein the second power source is a power source of the drive circuit during the conversion process.   Between the first power supply and the drive circuit, there is provided rectifying means having a forward direction from the first power supply side to the drive circuit side, and the second power supply and the drive circuit 4. The electric power according to claim 1, further comprising a rectifying unit having a forward direction from the second power supply side to the drive circuit side. Discharge control device for conversion system.   The discharge control of the power conversion system according to any one of claims 1 to 3, further comprising switching means for switching which of the first power source and the second power source is the power source of the drive circuit. apparatus.   The discharge control means performs a process of short-circuiting both electrodes of the capacitor by turning on both the high-potential side switching element and the low-potential side switching element. The discharge control device for a power conversion system according to any one of claims 5 to 6. The high-potential side switching element and the low-potential side switching element are voltage-controlled switching elements,
The discharge control means includes the at least one switching element so that the current in the non-saturation region of at least one of the high-potential side switching element and the low-potential side switching element is smaller than that during the process of converting to the predetermined value. Set the voltage to be applied to the conduction control terminal of
The discharge control device for a power conversion system according to claim 6, wherein the abnormality diagnosis unit diagnoses the presence or absence of the abnormality based on a value of a voltage applied to a conduction control terminal of the at least one switching element. The high-potential side switching element and the low-potential side switching element are voltage-controlled switching elements,
The discharge control means is configured to detect either one of the high-potential side switching element and the low-potential side switching element so that a current in a non-saturated region is smaller than the other one. The voltage applied to the conduction control terminal of each of the other switching elements is set,
The discharge control means switches either one of the switching states while the other is in the on state, and repeats both the on state and the off state a plurality of times. The process of generating the short circuit state of the electrode multiple times,
The abnormality diagnosis unit diagnoses the presence or absence of the abnormality based on whether at least one of an ON period and an OFF period of the one of the switching elements is within an allowable range. 8. A discharge control device for a power conversion system according to 7. A determination means for determining whether or not an abnormality has occurred in a member on which the power conversion system is mounted;
The discharge control unit short-circuits both electrodes of the capacitor by turning on both the high-potential side switching element and the low-potential side switching element when the determination unit determines that an abnormality has occurred. An abnormal discharge control means for performing the process of
A normal-time discharging unit that discharges the capacitor without performing the short-circuiting process when the opening / closing unit is in an open state and it is not determined that the abnormality has occurred. Item 10. The discharge control device for a power conversion system according to any one of Items 1 to 8.

Images