JP2015198461A - Inverter controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress increase of the DC link voltage and total amount of reflux current of an inverter, when a contactor connecting the inverter and a DC power supply is brought into an open state.SOLUTION: An inverter controller executes pre-shutdown control for bringing all switching elements 3 into an off state, and when the current Iu of an object arm, i.e., an arm of any one phase, goes zero after pre-shutdown control is started, executes partial active short control for bringing the upper stage side switching element 3 or a lower stage side switching element 3, in the arm of at least one phase out of the arms different from the objective arm, into an on state. Thereafter, the inverter controller executes full-shutdown control for bringing the switching elements 3, that have been controlled to the on state in all remaining arms, into the on state, when both currents Iv, Iw of arms of two phases different from the object arm go zero.

Description

  The present invention relates to a technique for driving and controlling an AC rotating electrical machine.

  For example, a high-output AC rotating electrical machine used for power of an electric vehicle or a hybrid vehicle is driven at a high voltage. Moreover, since the high voltage power supply mounted in such a motor vehicle is a direct current battery, it is converted into, for example, a three-phase alternating current by an inverter circuit using a switching element. The rotating electrical machine has not only a function as a motor that outputs power for driving a vehicle by electric energy but also a function as a generator that generates electric power by kinetic energy of a vehicle, an internal combustion engine, or the like. The electric power generated by the rotating electrical machine is regenerated and stored in the battery.

  By the way, an opening / closing device (contactor) may be provided between the battery and the rotating electrical machine, more specifically between the battery and the inverter. The contactor is, for example, a system main relay (SMR) configured using a relay. When the ignition key (IG key) of the vehicle is on (valid), the contact is closed and the IG key is off. In the state (invalid state), the contact opens and becomes non-conductive. That is, the battery and the inverter (and the rotating electrical machine) are electrically connected when the SMR is closed, and the electrical connection between the battery and the inverter (and the rotating electrical machine) is disconnected when the SMR is open. During normal operation, the open / close state of the SMR is also controlled according to the state of the IG key. However, when the IG key is on, the SMR may be released due to a vehicle failure or a collision. For example, when the power supply to the SMR is cut off, when an abnormality occurs in the SMR drive circuit, when the SMR mechanically fails due to vibration, shock, noise, etc., or when the circuit around the SMR is disconnected , Etc., the contact of the SMR may be opened, and the contactor may be opened.

  For this reason, when a contactor will be in an open state, shutdown control (SD control) which makes all the switching elements which constitute an inverter into an OFF state may be performed. On the DC side (DC link portion) of the inverter, a smoothing capacitor (DC link capacitor) that smoothes the DC voltage (DC link voltage) is often provided. When SD control is performed, the stator coil The electric power accumulated in the capacitor charges the smoothing capacitor via a free wheel diode (FWD) connected in antiparallel to the switching element. For this reason, the voltage between the terminals of the smoothing capacitor (DC link voltage) may increase in a short time. Increasing the capacity and withstand voltage of the smoothing capacitor in preparation for an increase in the DC link voltage leads to an increase in the size of the smoothing capacitor. In addition, it is necessary to increase the breakdown voltage of the inverter. As a result, downsizing of the rotating electrical machine drive device is hindered, and the component cost, manufacturing cost, and product cost are also affected.

  In addition, when the contactor is in an open state, an active short control (active short circuit control (ASC control)) in which some switching elements are turned on to return the current to, for example, zero vector sequence control (ZVS control) May be executed. For example, Japanese Patent Laying-Open No. 2011-55582 (Patent Document 1) discloses a control method in which all upper switching elements of an inverter are turned off and one or more of lower switching elements are turned on. (Patent Document 1: FIG. 2, paragraphs 158, 159, 165, etc.). In the ASC control, an increase in the DC link voltage can be suppressed, but a large current (reflux current) flows through the switching element and the stator coil. Further, a large current continues to flow until the electric power accumulated in the stator coil is consumed due to heat or the like. For this reason, a switching element and a stator coil may be consumed, and a lifetime may be reduced. Moreover, it becomes necessary to use a switching element corresponding to a large current, which may affect the component cost, manufacturing cost, and product cost.

JP 2011-55582 A

  In view of the above background, when the contactor connecting the inverter and the DC power supply is opened, the current flowing to the rotating electrical machine is reduced to zero while suppressing the increase of the DC link voltage of the inverter and the total amount of return current. Technology to do is desired.

In view of the above problems, the characteristic configuration of the inverter control device according to the present invention is:
Connected to a DC power source via a contactor and connected to an AC rotating electrical machine to perform power conversion between DC and three-phase AC, and an arm for one AC phase has an upper switching element and a lower switching element The inverter is configured with a rotating electrical machine driving device including an inverter configured by a series circuit with a switching element and a DC link capacitor that smoothes a DC link voltage that is a voltage on the DC side of the inverter as a control target. An inverter control device that controls switching of a switching element,
When the contactor is in an open state during rotation of the rotating electrical machine, pre-shutdown control is performed to turn off all the switching elements,
Furthermore, after the start of the pre-shutdown control, when the current of the target arm that is any one phase of the arm becomes zero, the arm of the at least one phase among the arms different from the target arm Perform partial active short control to turn on the upper switching element or the lower switching element,
After that, when both the currents of the two-phase arms different from the target arm become zero, the full shutdown is performed so that the switching elements that are controlled to be turned on in all the remaining arms are turned off. The point is to execute the control.

  According to this configuration, after the contactor is opened, the pre-shutdown control, the partial active short control, and the full shutdown control are executed at appropriate timing in time series. The shutdown control has a problem that the voltage between the terminals of the DC link capacitor (DC link voltage) greatly increases, and the active short control has a problem that a large current continues to circulate. However, as in this configuration, the shutdown control and the active short control are executed at appropriate timing in time series, thereby suppressing the voltage increase due to the shutdown control and suppressing the current due to the active short control. Since energy is supplied to the DC link capacitor in the pre-shutdown control, the return current when shifting to the partial active short control is reduced. Moreover, since the current of the arm to be shut down is zero at the time of transition from the partial active short control to the full shutdown control, it is possible to suppress an increase in the DC link voltage due to the shutdown. Thus, according to this configuration, when the contactor connecting the inverter and the DC power supply is in an open state, the increase in the DC link voltage of the inverter and the total amount of the return current are suppressed, and the current flows to the rotating electrical machine. The current can be zero.

  Here, after the start of the pre-shutdown control, the switching element that is turned on by the partial active short control has at least one phase among the phases in which the phase current flows when the current of the target arm becomes zero. It is preferable that the switching element constitutes the arm. In general, an inverter is configured to include a freewheel diode, and a forward current flows under a condition in which a forward bias is applied to the freewheel diode. Therefore, even if the switching element is in an off state, a phase current is generated. Flows. The switching element that is turned on by the partial active short control is a phase switching element in which the phase current flows through the free wheel diode when the partial active short control starts (when the current of the target arm becomes zero). If so, it is possible to directly control the flow of the phase current via the switching element.

  In the partial active short control, when the current of the target arm becomes zero, the upper side switching element or the lower side switching element of at least one phase arm is controlled to be in the ON state among the arms different from the target arm. The However, the inverter includes a freewheel diode, and when a current flows through the freewheel diode in an arm, even if the switching element connected in parallel to the freewheel diode is in the off state, the arm A current flows through. Therefore, in the partial active short control, there is no problem even if the switching element maintains the OFF state as long as the current continues to flow through the free wheel diode. In the partial active short control, a large current is circulated. Therefore, by maintaining the switching element of the arm through which the current flows through the free wheel diode in an OFF state, it is possible to suppress a decrease in the life of the switching element. . In other words, in the partial active short control, it is only necessary to turn on the switching element of the arm that does not flow current unless it is turned on among the arms other than the target arm. That is, when the inverter includes a free wheel diode connected in parallel to each switching element with the direction from the lower stage side to the upper stage side as a forward direction, the switching that is turned on when executing the partial active short control It is preferable that the element includes at least a switching element connected in parallel to the free wheel diode of the arm having the free wheel diode that is non-conductive in the forward direction in the arm different from the target arm. is there.

Circuit block diagram schematically showing the system configuration of the rotating electrical machine drive device Waveform diagram schematically showing a control example when the contactor is open IGBT 1 control example in Phase 1 and equivalent circuit diagram showing current flow Example of IGBT control in Phase 2 and equivalent circuit diagram showing current flow Example of IGBT control in Phase 2 and equivalent circuit diagram showing current flow The figure which shows the relationship between the control method suitable when the contactor is opened and the operating state of the rotating electrical machine

  Embodiments of an inverter control device according to the present invention will be described below with reference to the drawings. As shown in FIG. 1, the inverter control device 20 controls the rotary electric machine drive device 1 including the inverter 10 and the DC link capacitor 4 and controls the rotary electric machine 80 via the rotary electric machine drive device 1. As will be described later, the inverter 10 is connected to the DC power source (11) via the contactor 9, and is connected to an AC rotating electrical machine 80 to connect between DC and multiphase AC (here, three-phase AC). The power conversion device performs power conversion, and an AC one-phase arm is configured by a series circuit of an upper-stage switching element and a lower-stage switching element. The DC link capacitor 4 smoothes the DC link voltage Vdc that is the voltage on the DC side of the inverter 10. The rotating electrical machine 80 to be driven by the rotating electrical machine drive device 1 and the inverter control device 20 is a rotating electrical machine that serves as a driving force source for a vehicle such as a hybrid vehicle or an electric vehicle. The rotating electrical machine 80 as a vehicle driving force source is a rotating electrical machine that operates by multiphase alternating current (here, three-phase alternating current), and can function as both an electric motor and a generator.

  In a vehicle such as an automobile that cannot receive power from an overhead line such as a railway, a secondary battery (battery) such as a nickel metal hydride battery or a lithium ion battery is used as a power source for driving the rotating electrical machine 80, It is equipped with a DC power supply such as a double layer capacitor. In the present embodiment, for example, a high voltage battery 11 (DC power supply) with a power supply voltage of 200 to 400 [V] is provided as a DC power supply with a large voltage and a large capacity for supplying electric power to the rotating electrical machine 80. Since the rotating electrical machine 80 is an alternating current rotating electrical machine, an inverter 10 that performs power conversion between direct current and alternating current (here, three-phase alternating current) is provided between the high voltage battery 11 and the rotating electrical machine 80. Yes. The voltage between the positive power supply line P and the negative power supply line N on the DC side of the inverter 10 is hereinafter referred to as “DC link voltage Vdc”. The high voltage battery 11 can supply electric power to the rotating electrical machine 80 via the inverter 10 and can store electric power obtained by the rotating electrical machine 80 generating electric power.

  Between the inverter 10 and the high voltage battery 11, a smoothing capacitor (DC link capacitor 4) for smoothing the voltage between the positive and negative electrodes (DC link voltage Vdc) on the DC side of the inverter 10 is provided. The DC link capacitor 4 stabilizes a DC voltage (DC link voltage Vdc) that fluctuates according to fluctuations in power consumption of the rotating electrical machine 80. Between the DC link capacitor 4 and the high voltage battery 11, a contactor 9 capable of disconnecting the electrical connection between the circuit from the DC link capacitor 4 to the rotating electrical machine 80 and the high voltage battery 11 is provided. In the present embodiment, the contactor 9 is a mechanical relay that opens and closes based on a command from a vehicle ECU (Electronic Control Unit) 90 that is one of the highest-level control devices of the vehicle. For example, a system main relay (SMR: System Main Relay). When the ignition key (IG key) of the vehicle is on (valid), the contactor 9 closes the contact of the SMR and becomes conductive (connected), and when the IG key is off (invalid), the contactor 9 The contact of is opened and becomes a non-conductive state (open state). The inverter 10 is interposed between the high voltage battery 11 and the rotating electrical machine 80 via the contactor 9, and when the contactor 9 is in the connected state, the high voltage battery 11 and the inverter 10 (and the rotating electrical machine 80) are electrically connected to each other. When 9 is open, the electrical connection between the high voltage battery 11 and the inverter 10 (and the rotating electrical machine 80) is cut off.

  The inverter 10 converts the DC power having the DC link voltage Vdc into AC power of a plurality of phases (n is a natural number, n-phase, here, three phases) and supplies the AC power to the rotating electrical machine 80, and the AC generated by the rotating electrical machine 80 The power is converted to DC power and supplied to the DC power supply. The inverter 10 includes a plurality of switching elements. Switching elements include IGBTs (Insulated Gate Bipolar Transistors), power MOSFETs (Metal Oxide Semiconductor Field Effect Transistors), SiC-MOSFETs (Silicon Carbide-Metal Oxide Semiconductor FETs), SiC-SITs (SiC-Static Induction Transistors), GaN- It is preferable to apply a power semiconductor element capable of operating at a high frequency, such as a MOSFET (Gallium Nitride-MOSFET). As shown in FIG. 1, in this embodiment, IGBT3 is used as a switching element.

  For example, an inverter 10 that converts power between direct current and multiphase alternating current (here, three-phase alternating current) has a number of arms corresponding to each of the multiple phases (here, three phases) as is well known. Consists of a circuit. That is, as shown in FIG. 1, two IGBTs 3 are provided between the DC positive side (positive power supply line P on the positive side of the DC power supply) and the DC negative side (negative power supply line N on the negative side of the DC power supply) of the inverter 10. Are connected in series to form one arm. In the case of three-phase alternating current, this series circuit (one arm) is connected in parallel with three lines (three phases). That is, a bridge circuit in which a set of series circuits (arms) corresponds to each of the stator coils 8 corresponding to the U phase, the V phase, and the W phase of the rotating electrical machine 80 is configured.

  The intermediate point of the series circuit (arm) of each pair of IGBTs 3, that is, the IGBT 3 on the positive power supply line P side (upper IGBT (upper switching elements) 31, 33, 35: see FIG. 3 etc.) and the negative electrode The connection point with the IGBT 3 on the power supply line N side (lower-stage IGBT (lower-stage switching elements) 32, 34, 36: see FIG. 3 etc.) is the stator coil 8 (8u, 8v, 8w: FIG. 3 etc.) of the rotating electrical machine 80. Connected to each other). Each IGBT 3 is provided with a free wheel diode (FWD) 5 in parallel with the direction from the negative electrode “N” to the positive electrode “P” (the direction from the lower side to the upper side) as the forward direction.

  As shown in FIG. 1, the inverter 10 is controlled by an inverter control device 20. The inverter control device 20 is constructed using a logic circuit such as a microcomputer as a core member. For example, the inverter control device 20 uses a vector control method based on the target torque TM of the rotating electrical machine 80 provided as a request signal from another control device such as the vehicle ECU 90 via a CAN (Controller Area Network). The rotary electric machine 80 is controlled via the inverter 10 by performing the current feedback control. The actual current flowing through the stator coil 8 of each phase of the rotating electrical machine 80 is detected by the current sensor 12, and the inverter control device 20 acquires the detection result. Moreover, the magnetic pole position at each time of the rotor of the rotating electrical machine 80 is detected by the rotation sensor 13 such as a resolver, and the inverter control device 20 acquires the detection result. The inverter control device 20 performs current feedback control using the detection results of the current sensor 12 and the rotation sensor 13. The inverter control device 20 is configured to have various functional units for current feedback control, and each functional unit is realized by cooperation of hardware such as a microcomputer and software (program). . Since the current feedback control is known, a detailed description thereof is omitted here.

  In addition to the high voltage battery 11, a low voltage battery (not shown), which is a power source having a lower voltage than the high voltage battery 11, is mounted on the vehicle. The power supply voltage of the low voltage battery is, for example, 12 to 24 [V]. The low voltage battery and the high voltage battery 11 are insulated from each other and have a floating relationship with each other. The low-voltage battery supplies electric power to the inverter control device 20 and the vehicle ECU 90 as well as to electrical components such as an audio system, a lighting device, room lighting, instrument illumination, and a power window, and a control device that controls these components. The power supply voltage of the vehicle ECU 90 and the inverter control device 20 is, for example, 5 [V] or 3.3 [V].

  By the way, the gate terminal which is a control terminal of each IGBT3 which comprises the inverter 10 is connected to the inverter control apparatus 20 via the driver circuit 30, and each switching control is carried out individually. The high voltage system circuit for driving the rotating electrical machine 80 and the low voltage system circuit such as the inverter control device 20 having a microcomputer as a core are greatly different in operating voltage (circuit power supply voltage). For this reason, the driver circuit 30 (control signal drive) relays the gate drive signal (switching control signal) for each IGBT 3 by increasing the drive ability (for example, the ability to operate the subsequent circuit such as voltage amplitude and output current). Circuit). The gate drive signal of the IGBT 3 generated by the inverter control device 20 of the low voltage system circuit is supplied to the inverter 10 through the driver circuit 30 as a gate drive signal of the high voltage circuit system. The driver circuit 30 is configured using an insulating element such as a photocoupler or a transformer, or a driver IC, for example.

  As described above, the contactor 9 is connected when the ignition key (IG key) of the vehicle is on (valid), and is open when the IG key is off (invalid). During normal operation, the open / close state of the contactor 9 is also controlled according to the state of the IG key. However, when the IG key is in the ON state, the contactor 9 may be in an open state due to a vehicle failure or a collision. For example, when the power supply to the contactor 9 is interrupted, when the drive circuit of the contactor 9 is abnormal, when the contactor 9 is mechanically damaged due to vibration, shock, noise, etc., the circuit around the contactor 9 is disconnected. If this occurs, there is a possibility that the contactor 9 will be open. When the contactor 9 is in an open state, the supply of power from the high voltage battery 11 to the inverter 10 side is immediately cut off. Similarly, the regeneration of electric power from the rotating electrical machine 80 to the high voltage battery 11 via the inverter 10 is also blocked by the contactor 9.

  For this reason, when the contactor 9 is in an open state, shutdown control (SD control) that turns off all the IGBTs 3 constituting the inverter 10 may be performed. When the SD control is performed, the electric power stored in the stator coil 8 charges the DC link capacitor 4 via the FWD 5. For this reason, the voltage between the terminals of the DC link capacitor 4 (DC link voltage Vdc) may rise in a short time. Increasing the capacity and withstand voltage of the DC link capacitor 4 in preparation for the rise of the DC link voltage Vdc leads to an increase in the size of the capacitor. Further, it is necessary to increase the breakdown voltage of the inverter 10. As a result, downsizing of the rotating electrical machine drive device 1 is hindered, and the component cost, manufacturing cost, and product cost are also affected.

  Also, when the contactor 9 is in an open state, active short control (active short circuit control (ASC control)) in which some of the IGBTs 3 are turned on to return the current to, for example, zero vector sequence control (ZVS control) May be executed. The energy of the current (return current) is consumed by heat or the like in the IGBT 3 or the stator coil 8. In the ASC control, an increase in the DC link voltage Vdc can be suppressed, but a large current flows through the IGBT 3 and the stator coil 8. Since the reflux current continues to flow until the electric power accumulated in the stator coil 8 is consumed, there is a possibility that the lifetime of the IGBT 3 and the stator coil 8 may be reduced. In addition, it is necessary to use an element corresponding to a large current, which may affect part cost, manufacturing cost, and product cost. Further, due to heat generated by a large current or the like, the permanent magnet provided in the rotor of the rotating electrical machine 80 may be demagnetized, and the durability of the rotating electrical machine 80 may be reduced.

  The inverter control device 20 according to the present embodiment is characterized in that SD control and ASC control are combined to perform control (regenerative power suppression control) that suppresses regenerative power and zeros the current flowing through the rotating electrical machine 80. Have That is, when the contactor 9 that connects the inverter 10 and the high-voltage battery 11 is opened, the inverter control device 20 controls the rotating electrical machine 80 while suppressing an increase in the DC link voltage Vdc and the total amount of return current. Zero the flowing current. As described above, a low voltage battery (not shown) is provided separately from the high voltage battery 11, and the inverter control device 20 and the vehicle ECU 90 are operated by being supplied with electric power from the low voltage battery. In the present embodiment, description will be made assuming that power supply from the low-voltage battery to the inverter control device 20 and the vehicle ECU 90 is maintained even when the contactor 9 is in an open state.

  As shown in FIG. 1 and FIG. 3 and the like, the inverter 10 includes an upper-stage switching element (upper-stage IGBT (31, 33, 35)) and lower-stage switching whose arms for one AC phase are controlled in a complementary manner. It is constituted by a series circuit with an element (lower stage IGBT (32, 34, 36)). The inverter control device 20 executes pre-shutdown control (PSD control) that turns off all the three-phase switching elements 3 when the contactor 9 is in an open state during the rotation of the rotating electrical machine 80 (FIG. 2: Phase 1). Furthermore, when the current of the target arm, which is one of the one-phase arms, becomes zero after the PSD control is started, the inverter control device 20 sets the upper stage of at least one phase arm out of the arms different from the target arm. Partial active short control (PASC control) is performed to turn on the side IGBT (31, 33, 35) or the lower stage IGBT (32, 34, 36) (FIG. 2: Phase 2). In other words, the switching element that is turned on by the PASC control after the PSD control is started is the IGBT 3 in which the phase current flows in at least one phase arm. After that, when both the currents of the two-phase arms other than the target arm become zero, full shutdown control (FSD control) is performed so that the IGBTs 3 controlled to be in the on state in all the remaining arms are in the off state. ) Is executed (FIG. 2: Phase 3).

  Hereinafter, such regenerative power suppression control will be described. FIG. 2 is a waveform diagram schematically showing a control example when the contactor 9 is opened, FIG. 3 is a control example of the IGBT 3 in Phase 1 and an equivalent circuit diagram showing a current flow, and FIG. It is the equivalent circuit diagram which similarly shows the example of control of IGBT3 in Phase2, and the flow of an electric current. The time “t0” shown in FIG. 2 indicates the time when the contactor 9 is opened. When the contactor 9 is opened, the DC link voltage Vdc starts to rise. When the inverter control device 20 determines that the contactor 9 is in the open state (contactor open), it starts regenerative power suppression control. The determination that the contactor is open may be performed based on, for example, communication from the vehicle ECU 90, or may be performed based on the detection result of the voltage sensor 14 that detects the DC link voltage Vdc. The determination that the contactor is open may be made based on a rapid change in the current (battery current) of the high-voltage battery 11 detected by the battery current sensor 15. Here, the start of regenerative power suppression control is determined based on whether or not the DC link voltage Vdc detected by the voltage sensor 14 exceeds a determination threshold value for determining whether or not regenerative power suppression control is necessary. To do.

  When the regenerative power suppression control is started, first, PSD control is executed. In the PSD control, all the switching elements 3 of the three phases are controlled to be in the OFF state, and the DC link voltage Vdc increases. In the present embodiment, the DC link voltage Vdc increases due to the contactor 9 being opened, and the DC link voltage Vdc also increases due to PSD control. Therefore, for ease of explanation, in FIG. 2, the contactor open time “t0” and the PSD control start time “t1” are illustrated without being distinguished, and PSD control is executed from the contactor open. The DC link voltage Vdc increases over the period (Phase 1).

  FIG. 3 shows a control example of the IGBT 3 in Phase 1 and a current flow. In FIG. 3, an IGBT 3 indicated by a broken line indicates that switching control is performed in an off state, and an IGBT 3 indicated by a solid line indicates that it is controlled in an on state. Further, FWD5 indicated by a broken line indicates a non-conductive state, and FWD5 indicated by a solid line indicates a conductive state. As shown in FIG. 3, in the PSD control, all the IGBTs 3 are controlled to be in an off state. The U-phase current Iu flows through the U-phase upper stage FWD 51, the V-phase current Iv flows through the V-phase upper stage FWD 53, and the W-phase current Iw flows through the W-phase lower stage FWD 56 to charge the DC link capacitor 4. As a result, the DC link voltage Vdc rises to the voltage “V1”.

  PASC control is executed when the current of the target arm, which is one of the one-phase arms, becomes zero during the Phase 1 period, that is, during execution of PSD control. The PASC control is preferably executed at time “t2” shown in FIG. 2, but is not strict and may be executed before and after time “t2”. Since the execution of the PASC control is delayed after detecting that the current becomes zero, for example, it is preferable that the PASC control is executed in anticipation of the phase current being zero. FIG. 2 illustrates a mode in which PASC control is executed when the U-phase current Iu becomes zero during the Phase 1 period. Accordingly, the target arm is a U-phase arm, and as shown in FIG. 4, the V-phase lower stage IGBT 34 and the W-phase lower stage IGBT 36, which are different from the U-phase arm, are controlled to be in the ON state. In other words, the IGBT 3 that is turned on by the PASC control after the PSD control is started constitutes the arm of the phase in which the phase current flows when the PASC control starts (when the current of the target arm becomes zero). This is IGBT3. Since this state is a state in which only two of the three phases are turned on, it can be referred to as two-phase switching control. Thereby, a partial active short circuit by two phases of V phase and W phase is realized. As will be described later, the IGBT 3 that is turned on by the PASC control after the PSD control is started has both the phase current flowing when the PASC control is started (when the current of the target arm becomes zero). Instead of the IGBT 3 constituting the phase arm, the IGBT 3 constituting the arm of at least one of the phases in which the phase current flows may be used. Details will be described later.

  The U phase remains shut down. That is, partial shutdown is realized by the U phase. In shutdown, the electric power stored in the stator coil 8 charges the DC link capacitor 4 via the FWD 5, but the other two-phase currents are balanced and circulated while the phase current (Iu) is zero. Therefore, after time t2, the U-phase current Iu does not flow, and the increase of the DC link voltage Vdc stops at the voltage “V1”.

  FIG. 4 shows a control example of the IGBT 3 in Phase 2 and a current flow. As shown in FIG. 4, the V-phase current Iv flows through the V-phase lower-stage IGBT 34, and the W-phase current Iw flows through the W-phase lower-stage IGBT 36 and is connected to the W-phase lower-stage IGBT 36 in antiparallel. The lower stage FWD 56 also flows. Since the U phase is shut down, the V phase current Iv and the W phase current Iw are balanced. Therefore, as shown in FIG. 2, the V-phase current Iv and the W-phase current Iw become zero at the same time (here, time “t3”). Inverter control device 20 controls all remaining arms to the ON state when the currents of two-phase arms (here, V-phase and W-phase) other than the target arm (here U-phase) become zero. FSD control is performed to control the IGBT 3 (in this case, “34, 36”) to be turned off (FIG. 2: Phase 3). When the shutdown is performed, the electric power stored in the stator coil 8 charges the DC link capacitor 4 via the FWD 5, but the shutdown is performed with the phase currents (Iv, Iw) being zero. The DC link voltage Vdc does not rise.

  By the way, in Phase 2, since all the IGBTs 3 are controlled to be in an off state, the IGBT 3 is controlled to be in an on state so as to partially generate a reflux loop. This control is referred to as partial active short control (PASC control). ing. However, from a different viewpoint, it can be said that the shutdown control (SD control) is partially executed because the U phase is in a shutdown state. Therefore, the control executed from time “t2” (the control executed in Phase 2) can also be referred to as partial shutdown control (PSD control).

  As described above, at the time of PASC control, the upper-stage IGBT (31, 33, 35) or the lower-stage IGBT (32, 34, 36) of at least one phase arm is turned on among the arms different from the target arm. Controlled by the state. In the above, with reference to FIG. 4, the target arm is the U-phase, and the V-phase lower stage IGBT 34 and the W-phase lower stage IGBT 36 are controlled to be in the ON state. However, as shown in FIG. 5, the V-phase upper stage IGBT 33 and the W-phase upper stage IGBT 35 may be controlled to be in the ON state. In this case, the V-phase current Iv flows through the V-phase upper stage IGBT 33 and the V-phase upper stage FWD 53, and the W-phase current Iw flows through the W-phase upper stage IGBT 35 and circulates.

  In the above description, the upper IGBT (31, 33, 35) or the lower IGBT (32, 34, 36) of both arms other than the target arm is controlled to be in the ON state. It is sufficient that the upper stage IGBT (31, 33, 35) or the lower stage IGBT (32, 34, 36) of at least one phase arm is controlled to be in the ON state. In other words, in the above, the target arm is the U-phase, the V-phase lower-stage IGBT 34 and the W-phase lower-stage IGBT 36 are controlled to be in the ON state (see FIG. 4), and the V-phase upper-stage IGBT 33 and W The form (refer FIG. 5) with which the upper phase side IGBT35 was controlled by the ON state was illustrated. However, the target arm may be a U-phase, and only the V-phase lower stage IGBT 34 may be controlled to be in an on state, and only the W-phase upper stage IGBT 35 may be controlled to be in an on state.

  For example, when the target arm is the U-phase and only the V-phase lower stage IGBT 34 is controlled to be on, the reflux loop shown in FIG. 4 is formed via the V-phase lower stage IGBT 34 and the W-phase lower stage FWD 56. Is done. Similarly, when the target arm is the U-phase and only the W-phase upper stage IGBT 35 is controlled to be in the ON state, the reflux shown in FIG. 5 is performed via the V-phase upper stage FWD 53 and the W-phase upper stage IGBT 35. A loop is formed. That is, the IGBT 3 that is turned on when the PASC control is executed includes at least the IGBT 3 that is connected in parallel to the FWD 5 of the arm having the FWD 5 that is non-conductive in the forward direction, among the arms different from the target arm. It only has to be.

  Referring to FIG. 3, among the arms (V phase, W phase) different from the target arm (U phase), the FWD 5 of the arm having the FWD 5 in the non-conductive state in the forward direction is the V-phase lower stage FWD 54, Or it is W phase upper stage FWD55. Accordingly, the IGBT 3 that is connected in parallel to the FWD 5 that is non-conductive in the forward direction is the V-phase lower stage IGBT 34 or the W-phase upper stage IGBT 35 that is connected in parallel to the V-phase lower stage FWD 54. Even if the IGBT 3 connected in parallel to the forward FWD 5 is not controlled to be turned on again, a reflux loop is formed through the conductive FWD 5. For example, the V-phase lower-stage IGBT 34 controlled to be in the ON state can form a reflux loop through the W-phase lower-stage FWD 56 that is already in a conductive state. May not be controlled to the on state. Similarly, the W-phase upper stage IGBT 35 controlled to be in the ON state can form a reflux loop through the V-phase upper stage side FWD 53 that is already in a conductive state. The IGBT 33 may not be controlled to the on state. Thus, a state in which only one of the three phases is turned on can also be referred to as single phase switching control.

  In this way, by turning on only one phase, a large current due to ASC control is released to the FWD 5, and the consumption of the IGBT 3 due to the large current flowing can be suppressed, and the influence on the life can be reduced. Naturally, when the IGBT 3 for only one phase is controlled to be in the ON state in the PASC control, if the IGBT 3 for only one phase is controlled to be in the OFF state in the subsequent FSD control, all the IGBTs 3 are turned off. be able to.

  As described above, by combining the SD control and the ASC control, it is possible to appropriately execute the control for reducing the current flowing through the rotating electrical machine 80 to zero. According to the simulation by the inventor, for example, compared with the case where the SD control is simply executed in response to the contactor open, the DC link voltage Vdc can be reduced even if the capacitance of the DC link capacitor 4 is about 3/4. Has been confirmed to be about 4/5. In other words, the increase in the DC link voltage Vdc is suppressed by the regenerative power suppression control, and the DC link capacitor 4 can be downsized. In addition, the maximum value of the phase current is approximately ½ compared to the case where the ASC control is simply executed in response to the contactor opening. That is, the phase current is also suppressed by the regenerative power suppression control. Therefore, it is possible to suppress a decrease in life due to the consumption of the stator coil 8 and the IGBT 3. That is, it has been confirmed by simulation that the rated current and the withstand voltage are satisfied under the conditions of the maximum regenerative power point and the maximum voltage of the inverter 10.

  The inverter control device 20 according to the present embodiment executes regenerative power suppression control (SD-ASC mixed control) that appropriately sets the current flowing through the rotating electrical machine 80 to zero by combining SD control and ASC control. In the SD control, the ASC control, and the SD-ASC mixed control, there are appropriate regions according to the operation state of the rotating electrical machine 80 when the contactor is opened. FIG. 6 shows regions where the respective control methods are suitable on the operation map represented by the rotational speed and torque of the rotating electrical machine 80. In the region where the rotational speed is high, the region “defg” (region “R2”) in FIG. 6 has a high electromotive force (EMF: Electromotive Force) by the rotating electrical machine 80, and therefore ASC control is suitable. A line “dg” represents a boundary where the back electromotive force (BEMF) is equal to or higher than the DC link voltage Vdc. SD control is suitable for the region where the rotational speed is low, that is, the region “0acdg” (region “R1 + R3”) in FIG. That is, the SD control is executed when the DC link voltage Vdc is larger than the electromotive force generated by the rotating electrical machine 80.

  If the inverter control device 20 is constructed so that SD control is possible in all areas “0acdg” where SD control is suitable, a design is required in consideration of the increase in the DC link voltage Vdc in the area. For example, a switching element such as an IGBT 3 is required to have a high breakdown voltage, and the DC link capacitor 4 is also required to have a large capacity and a high breakdown voltage. However, if the increase in the DC link voltage Vdc can be suppressed in the region “bcd” (region “R3”) where the rotational speed and torque are high, those requirements can be relaxed. Therefore, the above-described regenerative power suppression control is preferably applied in the region “bcd” (region “R3”) in FIG.

[Other Embodiments]
Hereinafter, other embodiments of the present invention will be described. Note that the configuration of each embodiment described below is not limited to being applied independently, and can be applied in combination with the configuration of other embodiments as long as no contradiction arises.

  As described above, when the contactor 9 is in the open state, the DC link voltage Vdc immediately rises. Therefore, it is desirable that the inverter control device 20 quickly determines that the contactor 9 is in the open state and starts the regenerative power suppression control. Therefore, in the above description, the state of the contactor 9 is not acquired via the vehicle ECU 90 by using CAN or the like that generally requires communication time, but based on the detection result of the DC link voltage Vdc, the contactor 9 can be quickly obtained. An example is shown in which it can be determined that is in an open state. As another aspect, the contactor is opened based on a sudden change in the current (battery current) of the high voltage battery 11 detected by the battery current sensor 15 provided between the high voltage battery 11 and the DC link capacitor 4. May be determined. When the contactor 9 is in the open state, the electrical connection state between the high voltage battery 11 and the subsequent circuit (DC link capacitor 4, inverter 10, rotating electrical machine 80, etc.) changes abruptly. For this reason, the current flowing in and out of the high voltage battery 11 also changes abruptly. Therefore, in this case as well, the inverter control device 20 determines that the contactor 9 is in the open state based on the detection result of the current of the high voltage battery 11 rather than acquiring the state of the contactor 9 via the vehicle ECU 90 using CAN or the like. It is possible to quickly determine that it has become. Thus, in order to prevent the voltage between the terminals (DC link voltage Vdc) of the smoothing capacitor (DC link capacitor 4) from rising in a short time due to the contactor opening, it is particularly important to detect the contactor open quickly. It is.

  The present invention can be used in an inverter control device that drives and controls an AC rotating electrical machine via an inverter.

1: Rotating electrical machine drive device 3: IGBT (switching element)
4: DC link capacitor 5: Freewheel diode 9: Contactor 10: Inverter 11: High voltage battery (DC power supply)
20: Inverter control devices 31-36: IGBT (switching element)
51-56: Freewheel diode 80: Rotating electric machine Vdc: DC link voltage

Claims (3)

Connected to a DC power source via a contactor and connected to an AC rotating electrical machine to perform power conversion between DC and three-phase AC, and an arm for one AC phase has an upper switching element and a lower switching element The inverter is configured with a rotating electrical machine driving device including an inverter configured by a series circuit with a switching element and a DC link capacitor that smoothes a DC link voltage that is a voltage on the DC side of the inverter as a control target. An inverter control device that controls switching of a switching element,
When the contactor is in an open state during rotation of the rotating electrical machine, pre-shutdown control is performed to turn off all the switching elements,
Furthermore, after the start of the pre-shutdown control, when the current of the target arm that is any one phase of the arm becomes zero, the arm of the at least one phase among the arms different from the target arm Perform partial active short control to turn on the upper switching element or the lower switching element,
After that, when both the currents of the two-phase arms different from the target arm become zero, the full shutdown is performed so that the switching elements that are controlled to be turned on in all the remaining arms are turned off. An inverter control device that executes control.   After the start of the pre-shutdown control, the switching element that is turned on by the partial active short control has at least one phase of the arm in the phase in which the phase current flows when the current of the target arm becomes zero The inverter control device according to claim 1, wherein the switching element constitutes the switching element. The inverter includes a free wheel diode connected in parallel to each switching element with the direction from the lower side to the upper side as a forward direction.
The switching element that is turned on when executing the partial active short control includes the free wheel diode in the arm having the free wheel diode that is non-conductive in the forward direction among the arms different from the target arm. The inverter control device according to claim 1, further comprising at least a switching element connected in parallel.

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