Inverter control method and inverter controller

Abstract

To provide an inverter control method and a controller, capable of protecting a smoothing capacitor when performing switching between upper side short circuit control and lower side short circuit control in the case of performing ASC control in a system using an open winding type rotary electric machine.SOLUTION: A method includes: alternately executing upper side short circuit control of turning on upper arms of a first inverter 18 and a second inverter 19 and turning off lower arms of the first inverter 18 and the second inverter 19, and lower side short circuit control of turning off the upper arms of the first inverter 18 and the second inverter 19 and turning on the lower arms of the first inverter 18 and the second inverter 19; and, when performing switching between the upper side short circuit control and the lower side short circuit control; acquiring phase currents iu, iv, iw, being currents flowing in respective phases of an open winding type rotary electric machine (10); and, on the basis of the phase currents iu, iv, iw, performing switching of the first inverter 18 and the second inverter 19 at different timing for respective phases.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a method and a control device for an inverter that connects a DC power source and a rotating electric machine via a smoothing capacitor. [Background technology]

[0002] Patent Document 1 discloses an inverter device that alternately performs first switching control and second switching control. The first switching control is a control that turns on all switching elements connected to the positive side of a DC power supply and turns off all switching elements connected to the negative side of the DC power supply. The second switching control is a control that turns off all switching elements connected to the positive side of the DC power supply and turns on all switching elements connected to the negative side of the DC power supply. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5857394 Summary of the Invention [Problem to be solved by the invention]

[0004] The inverter has a pair of switching elements that constitute an upper arm and a lower arm for each phase of the rotating electric machine. The inverter also connects a DC power source to the rotating electric machine via a smoothing capacitor. When an abnormality occurs in the control of the rotating electric machine, such as when the rotating electric machine reaches overspeed, a short circuit may be formed between the inverter and the rotating electric machine by turning on all of either the upper arms or the lower arms of each phase and turning off all of the other arms. This type of short circuit control is called ASC (active short circuit) control or three-phase short circuit control.

[0005] The ASC control can be performed by short-circuit control that turns on all upper arms and turns off all lower arms (hereinafter referred to as upper-side short-circuit control), or by short-circuit control that turns off all upper arms and turns on all lower arms (hereinafter referred to as lower-side short-circuit control). However, when the rotating electric machine is rotating, heat and current may be concentrated in a specific arm, making that specific arm more susceptible to deterioration. For this reason, when the rotating electric machine is rotating, it is preferable to perform the ASC control by alternately switching between the upper-side short-circuit control and the lower-side short-circuit control.

[0006] To switch between upper-side short-circuit control and lower-side short-circuit control, it is necessary to switch the upper arm and the lower arm of each phase. At this time, if the upper arm and the lower arm are turned on simultaneously and a through current flows, there is a risk of damage to switching elements, etc. For this reason, a dead time is provided when switching a pair of upper and lower arms to ensure that both of them are turned off. However, if a dead time is simply provided when switching between upper-side short-circuit control and lower-side short-circuit control, depending on the current that flowed into the rotating electric machine before the dead time (the induced voltage of the rotating electric machine), a large current may flow into the smoothing capacitor during the dead time, which may damage the smoothing capacitor.

[0007] The present invention aims to provide an inverter control method and control device that can protect a smoothing capacitor when switching between upper-side short-circuit control and lower-side short-circuit control in a system using an open-winding rotating electric machine, where ASC control is performed. [Means for solving the problem]

[0008] One aspect of the present invention is an inverter control method for controlling a first inverter that connects one end of a stator coil of an open-winding rotating electric machine to a DC power source via a smoothing capacitor, and a second inverter that connects the other end of the stator coil to the DC power source via a smoothing capacitor. This inverter control method alternately performs upper-side short-circuit control, which turns on the upper arms of the first inverter and the second inverter and turns off the lower arms of the first inverter and the second inverter, and lower-side short-circuit control, which turns off the upper arms of the first inverter and the second inverter and turns on the lower arms of the first inverter and the second inverter. When switching between the upper-side short-circuit control and the lower-side short-circuit control, phase currents that flow through each phase of the open-winding rotating electric machine are obtained, and the first inverter and the second inverter are switched at different timings for each phase based on the phase currents. [Effects of the Invention]

[0009] According to the present invention, when ASC control is performed in a system using an open-winding rotating electric machine, an inverter control method and control device can be provided that can protect a smoothing capacitor when switching between upper-side short-circuit control and lower-side short-circuit control. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a block diagram showing the configuration of an electric vehicle according to the first embodiment. [Figure 2] FIG. 2 is a circuit diagram showing the configuration of the inverter. [Figure 3] FIG. 3 is an explanatory diagram showing a PWM signal in the normal mode. [Figure 4] FIG. 4 is a block diagram showing the configuration of a portion of the PWM control unit that is involved in ASC control. [Figure 5] FIG. 5 is a time chart showing an example of the reference ASC switching signal, the phase current, and the ASC switching signal of each phase. [Figure 6] FIG. 6 is a flowchart relating to the ASC control. [Figure 7]FIG. 7 is a block diagram showing an example of a PWM signal in the ASC mode. [Figure 8] FIG. 8 is an explanatory diagram relating to the relationship between the phase current and the timing at which the first inverter and the second inverter are switched. [Figure 9] FIG. 9 is an explanatory diagram showing transitions of phase currents in a comparative example. [Figure 10] FIG. 10 is an explanatory diagram showing the transition of the phase current in this embodiment. [Figure 11] FIG. 11 is a time chart showing an example of the reference ASC switching signal, phase currents, and ASC switching signals of each phase in the second embodiment. [Figure 12] FIG. 12 is a flowchart relating to the ASC control of the second embodiment. [Figure 13] FIG. 13 is a time chart showing an example of a PWM signal in the first ASC mode (ASC1). [Figure 14] FIG. 14 is a time chart showing an example of a PWM signal in the second ASC mode (ASC2). [Figure 15] FIG. 15 is an explanatory diagram showing transitions of phase currents in the first ASC mode (ASC1). [Figure 16] FIG. 16 is an explanatory diagram showing transitions of phase currents in the second ASC mode (ASC2). [Figure 17] FIG. 17 is a block diagram showing the configuration of the first PWM control unit and the second PWM control unit according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0012] [First embodiment] Fig. 1 is a block diagram showing the configuration of an electric vehicle 100 according to a first embodiment. The electric vehicle 100 is a vehicle driven by electric power, and specifically, is an electric vehicle, a hybrid vehicle, or the like. As shown in Fig. 1, the electric vehicle 100 includes a rotating electric machine 10, a battery 11, an inverter 12, and a controller 13.

[0013] The rotating electric machine 10 is an electric motor or a generator. In this embodiment, the rotating electric machine 10 is an electric motor and functions as a driving force source for the electric vehicle 100. More specifically, the rotating electric machine 10 of this embodiment is a three-phase AC synchronous motor having three phases: U phase, V phase, and W phase. Currents flowing through the U, V, and W phases (hereinafter collectively referred to as phase currents i u ,i v ,i w The electrical angle θ of the rotor (not shown) is acquired by the rotation sensor 15 as needed.

[0014] In this embodiment, the rotating electric machine 10 is of a so-called open winding type. That is, the stator coils of the U, V, and W phases of the rotating electric machine 10 are not connected, and the stator coils of each phase (U, V, and W) are connected to the inverter 12, respectively.

[0015] The battery 11 is a DC power supply that supplies power to the rotating electrical machine 10. The battery 11 is configured by, for example, a lithium ion battery. In this embodiment, the battery 11 is rechargeable.

[0016] The inverter 12 converts DC power input from the battery 11 into AC power using PWM (Pulse Width Modulation) control and supplies it to the rotating electrical machine 10. The inverter 12 is connected to the battery 11 via a relay 16. A DC voltage V dc is acquired by the voltage sensor 17 as needed.

[0017] In this embodiment, since the rotating electric machine 10 is of an open winding type, the inverter 12 includes a first inverter 18 (INV1) and a second inverter 19 (INV2). The first inverter 18 (INV1) connects one end of the stator coils (U, V, W) of each phase of the rotating electric machine 10 to the battery 11. The second inverter 19 (INV2) connects the other end of the stator coils (U, V, W) of each phase to the battery 11, which is a DC power source. The first inverter 18 and the second inverter 19 work together to convert DC power output from the battery 11 into AC power and supply it to the rotating electric machine 10. As a result, the inverter 12 (first inverter 18 and second inverter 19) converts the phase current i u ,i v ,i w Control.

[0018] The controller 13 is a control device that comprehensively controls the operation of each part of the electric vehicle 100. In this embodiment, the controller 13 particularly functions as a control device for the inverter 12. The controller 13 is configured, for example, with one or more computers or circuits. The controller 13 is also programmed to control the operation of each part at a predetermined control cycle τ.

[0019] Specifically, the controller 13 includes a torque control unit 21, a voltage distribution unit 22, a coordinate conversion unit 23, a PWM control unit 24, a PWM signal generator 25, a coordinate conversion unit 26, a rotation speed calculation unit 27, and an abnormality detection unit 28.

[0020] The torque control unit 21 controls the output torque of the rotary electric machine 10 to be equal to the torque command value T * The dq-axis voltage command value v d * ,v q * Calculate the following.

[0021] Torque command value T *is a command value (target value) for the torque to be output by the rotary electric machine 10, and represents a torque requested by a driver or the like to the electric vehicle 100. The controller 13 controls the torque command value T * The controller 13 calculates (determines) the torque command value T * Instead of calculating it by itself, the torque command value T * In this embodiment, for simplicity, the torque command value T * is assumed to be known.

[0022] dq-axis voltage command value v d * ,v q * is the command value (target value) for the voltage in the dq-axis coordinate system that rotates together with the rotor. Note that the dq-axis voltage command value v d * ,v q * is the d-axis voltage v d The d-axis voltage command value v d * and the q-axis voltage v q The q-axis voltage command value v q * It consists of:

[0023] More specifically, the torque control unit 21 calculates the torque command value T * , DC voltage V dc , dq-axis current i d ,i q , and the rotation speed N, the dq-axis voltage command value v is calculated by the so-called current vector control (CVC) or voltage phase control (VPC). d * ,v q * Calculate the dq axis current i d ,i q is the d-axis current i d and q-axis current i q In this embodiment, the dq-axis current i d ,i q is the detected value, and the phase current iu ,i v ,i w and the electrical angle θ. The rotation speed N [rpm] is a detected value or an estimated value. In this embodiment, the rotation speed N is calculated by the rotation speed calculation unit 27 based on the electrical angle θ.

[0024] The voltage distribution unit 22 calculates the dq-axis voltage command value v d * ,v q * is used as the dq-axis voltage command value for the first inverter 18 (hereinafter referred to as the first dq-axis voltage command value v d1 * ,v q1 * ) and the dq-axis voltage command value for the second inverter 19 (hereinafter referred to as the second dq-axis voltage command value v d2 * ,v q2 * Specifically, the voltage distribution unit 22 distributes the d-axis and q-axis voltage command values v calculated by the torque control unit 21 according to the following equation (1): d * ,v q * The first dq-axis voltage command value v d1 * ,v q1 * and the second dq-axis voltage command value v d2 * ,v q2 * The first dq-axis voltage command value v d1 * ,v q1 * is the dq-axis voltage command value for the first inverter 18, and the second dq-axis voltage command value v d2 * ,v q2 * are dq-axis voltage command values for the second inverter 19.

[0025]

number

[0026] The coordinate conversion unit 23 converts the dq-axis coordinate system into the UVW coordinate system to calculate three-phase voltage command values based on the dq-axis voltage command values and the electrical angle θ. The three-phase voltage command values are command values for voltages to be applied to the UVW phases of the rotating electric machine 10 via the inverter 12.

[0027] The coordinate conversion unit 23 includes a first conversion unit 31 and a second conversion unit 32 .

[0028] The first conversion unit 31 converts the first dq-axis voltage command value v d1 * ,v q1 * and the electrical angle θ, the first three-phase voltage command value v u1 * ,v v1 * ,v w1 * The first three-phase voltage command value v u1 * ,v v1 * ,v w1 * are command values for the voltages to be applied to the respective phases of the rotating electrical machine 10 via the first inverter 18. The first three-phase voltage command value v u1 * ,v v1 * ,v w1 * is the first U-phase voltage command value v u1 * , the first V-phase voltage command value v v1 * , and the first W-phase voltage command value v w1 * It consists of:

[0029] The second conversion unit 32 converts the second dq-axis voltage command value v d2 * ,v q2 * and the electrical angle θ, the second three-phase voltage command value v u2 * ,v v2 * ,v w2 * The second three-phase voltage command value vu2 * ,v v2 * ,v w2 * is a command value for the voltage to be applied to each phase via the second inverter 19. The second three-phase voltage command value v u2 * ,v v2 * ,v w2 * is the second U-phase voltage command value v u2 * , the second V-phase voltage command value v v2 * , the second W-phase voltage command value v w2 * It consists of:

[0030] More specifically, the first conversion unit 31 converts the first three-phase voltage command value v u1 * ,v v1 * ,v w1 * The second conversion unit 32 calculates the second three-phase voltage command value v u2 * ,v v2 * ,v w2 * Calculate the following.

[0031]

number

[0032] The PWM control unit 24 calculates a duty command value that determines the duty ratio in PWM control.

[0033] Specifically, the PWM control unit 24 includes a first PWM control unit 33 and a second PWM control unit 34. The first PWM control unit 33 calculates a first duty command value used to control the first inverter 18. The first duty command value is made up of duty command values (Duty_U1, Duty_V1, Duty_W1) for each of the UV and W phases. Hereinafter, the first duty command values Duty_U1, Duty_V1, Duty_W1 may be abbreviated as Duty_UVW1, etc. The second PWM control unit 34 calculates a second duty command value used to control the second inverter 19. The second duty command value is made up of duty command values (Duty_U2, Duty_V2, Duty_W2) for each of the UV and W phases. In the following, the second duty command values Duty_U2, Duty_V2, and Duty_W2 may be abbreviated as Duty_UVW2, etc.

[0034] The PWM control unit 24 also includes an output determination unit 35. The output determination unit 35 determines whether a gate enable signal S GP and the generation mode of the duty command value (Duty_UVW1, Duty_UVW2) (hereinafter referred to as the duty command value generation mode S mode Set or change the

[0035] Gate enable signal S GP is a signal that uniformly enables or disables gate voltage control of the switching elements. GP is "enabled", the inverter 12 is enabled. GP When is "prohibited", the inverter 12 is effectively disabled.

[0036] In this embodiment, the output determination unit 35 determines whether the abnormality detection unit 28 outputs the status signal S state , and the absolute value |N| of the rotation speed N, the gate enable signal S GP and the generation mode of the duty command value (Duty_UVW1, Duty_UVW2) (hereinafter referred to as the duty command value generation mode S mode Specifically, the output determination unit 35 sets or changes the gate enable signal SGP and duty command value generation mode S mode Set or change the

[0037] [Table 1]

[0038] As shown in Table 1, the status signal S state indicates "normal" and the rotating electrical machine 10 can be driven without any problems, the PWM control unit 24 outputs the gate enable signal S regardless of the absolute value |N| of the rotation speed N. GP is set to "Permitted" and the duty command value generation mode S mode is set to the normal mode. The normal mode is a mode in which duty command values (Duty_UVW1, Duty_UVW2) for driving the rotating electric machine 10 are generated. In the normal mode, the first PWM control unit 33 generates the first three-phase voltage command value v u1 * ,v v1 * ,v w1 * Similarly, in the normal mode, the second PWM control unit 34 calculates the second three-phase voltage command value v u2 * ,v v2 * ,v w2 * The second duty command value Duty_UVW2 [%] is calculated based on the above.

[0039]

number

[0040] Status signal S state indicates "abnormal" and there is a problem in driving the rotating electrical machine 10, the output determination unit 35 generates a gate permission signal S based on the absolute value |N| of the rotation speed N. GP and duty command value generation mode S mode Set.

[0041] Specifically, the status signal S state is "abnormal" and the absolute value of the rotation speed N |N| is greater than the rotation speed upper limit N MAX When |N|>N MAX ), the output determination unit 35 outputs the gate permission signal S GP is set to "Permitted" and the duty command value generation mode S mode Set to ASC mode. Upper limit of rotation speed N MAX are determined in advance by adaptation based on experiments, simulations, etc. The ASC mode is a mode in which duty command values (Duty_UVW1, Duty_UVW2) for forming a short circuit between the inverter 12 and the rotating electrical machine 10 are generated.

[0042] Also, as shown in Table 1, the status signal S state is "abnormal" and the absolute value of the rotation speed N |N| is greater than the rotation speed upper limit N MAX When |N|≦N MAX ), the output determination unit 35 outputs the gate permission signal S GP is set to "prohibited." In this case, the first PWM control unit 33 and the second PWM control unit 34 do not generate duty command values (Duty_UVW1, Duty_UVW2). Therefore, the rotary electric machine 10 is stopped without performing ASC control.

[0043] The PWM signal generator 25 generates a gate enable signal S GP When the duty command value (Duty_UVW1, Duty_UVW2) is compared and matched with the carrier signal CS, the inverter 12 generates a driving signal (hereinafter referred to as a PWM signal) D for each switching element of the inverter 12. uu1 * ~D wl1 * ,D uu2 * ~D wl2 * The inverter 12 generates the PWM signal D uu1 * ~D wl1 * ,D uu2* ~D wl2 * By controlling the on / off of the switching elements in accordance with the above, drive control or ASC control of the rotary electric machine 10 is performed. For simplicity, in this embodiment, the carrier signal CS is assumed to be a triangular wave having a fixed period (2τ).

[0044] In this embodiment, the PWM signal generator 25 includes a first PWM signal generator 36 and a second PWM signal generator 37. The first PWM signal generator 36 generates a PWM signal D that controls the on / off of a switching element of the first inverter 18 by comparing and matching the carrier signal CS with the first duty command value Duty_UVW1. uu1 * ~D wl1 * The second PWM signal generator 37 generates a PWM signal D that controls the on / off of the switching element of the second inverter 19 by comparing and matching the carrier signal CS with the second duty command value Duty_UVW2. uu2 * ~D wl2 * Generates a gate enable signal S GP When is "prohibited", the first PWM signal generator 36 and the second PWM signal generator 37 generate the PWM signal D uu1 * ~D wl1 * ,D uu2 * ~D wl2 * Stop generating.

[0045] The coordinate conversion unit 26 converts the phase current i u ,i v ,i w and the electrical angle θ, the dq-axis current i d ,i q Specifically, the coordinate conversion unit 26 calculates the dq-axis current i d ,i q Calculate the following.

[0046]

number

[0047] The rotation speed calculation unit 27 calculates the rotation speed N based on the electrical angle θ. Specifically, the rotation speed calculation unit 27 calculates the rotation speed N by converting the amount of change per unit time (dθ / dt) of the electrical angle θ using the number p of pole pairs of the rotating electric machine 10 according to the following equation (7).

[0048]

number

[0049] In this embodiment, the rotation speed N is used as a parameter representing the rotation state of the rotating electric machine 10 in the drive control and ASC control of the rotating electric machine 10, but this is not limiting. For example, instead of the rotation speed N, an electrical angle θ, an electrical angular velocity, a mechanical angle, a mechanical angular velocity, or the like can be used as a parameter representing the rotation state of the rotating electric machine 10. In this case as well, the drive control and ASC control of the rotating electric machine 10 can be performed.

[0050] The abnormality detection unit 28 detects an abnormality in the system that drives the rotating electric machine 10, i.e., whether or not there is a problem in driving the rotating electric machine 10. In this embodiment, the abnormality detection unit 28 monitors the rotation speed N of the rotating electric machine 10, and detects whether or not the absolute value |N| of the rotation speed N is equal to or exceeds the upper limit value N of the rotation speed. MAX and the rotating electrical machine 10 reaches an over-rotation state, the abnormality detection unit 28 determines that an abnormality has occurred in the system. u ,i v ,i w By monitoring these phase currents i u ,i v ,i wWhen any of these exceeds a predetermined threshold and reaches an overcurrent state, it is determined that an abnormality has occurred in the system. The abnormality detection unit 28 can also determine that an abnormality has occurred in the system by monitoring parameters other than those described above, such as the voltage and temperature of the rotating electric machine 10 and the inverter 12 (switching element). The abnormality detection unit 28 can also determine that an abnormality has occurred in the system when it detects a failure in the current sensor 14, the voltage sensor 17, or another detector not shown. In this embodiment, for simplicity, it is assumed that the abnormality detection unit 28 detects over-rotation and over-current as system abnormalities, as described above.

[0051] The abnormality detection unit 28 outputs the result of the abnormality detection as a status signal S state In this embodiment, the state signal S state is a signal that indicates either "normal" or "abnormal."

[0052] Furthermore, when the abnormality detection unit 28 detects an abnormality in the system, it further outputs a relay cut signal S if necessary depending on the cause of the abnormality. RC In this case, the relay 16 is turned off, and the connection between the battery 11 and the inverter 12 is forcibly released. In this embodiment, the abnormality detection unit 28 outputs a relay cut signal S when it detects an over-speed or an over-current. RC Therefore, when overspeed or overcurrent occurs, the relay 16 is forcibly turned off, and the connection between the battery 11 and the inverter 12 is released.

[0053] 2 is a circuit diagram showing the configuration of the inverter 12. As shown in FIG. 2, the inverter 12 includes a smoothing capacitor 39, a first inverter 18 which is a first bridge circuit formed by a plurality of switching elements Q1 to Q6, and a plurality of switching elements Q7 to Q8. 12 and a second inverter 19 which is a second bridge circuit formed by

[0054] The smoothing capacitor 39 is provided at the input terminal of the inverter 12 and smoothes the input voltage from the battery 11. The voltage at the smoothing capacitor 39 is the DC voltage V dc Switching elements Q1 to Q 12 are configured using power semiconductor elements such as IGBTs (insulated gate bipolar transistors) and MOSFETs (metal oxide semiconductor field effect transistors), and each includes a free wheel diode. 12 When controlled to be on, the switching elements Q1 to Q6 are able to conduct in the forward direction (from the positive electrode side to the negative electrode side of the battery 11), and are unable to conduct when controlled to be off. Also, when reverse bias occurs, the switching elements Q1 to Q6 are able to conduct in the reverse direction (from the negative electrode side to the positive electrode side of the battery 11) due to the free wheel diodes.

[0055] The switching elements Q1 to Q6 that constitute the first inverter 18 constitute legs for the UV phases as follows.

[0056] The switching elements Q1 and Q2 configure a U-phase leg (hereinafter referred to as the first U-phase leg) of the first inverter 18. That is, one end of the U-phase stator coil (U) is connected between the series-connected switching elements Q1 and Q2. The switching element Q1 is the upper arm of the first U-phase leg and is connected to the positive side (high side) of the battery 11. The switching element Q2 is the lower arm of the first U-phase leg and is connected to the negative side (low side) of the battery 11. The PWM signal that controls the on / off of the switching element Q1 is D uu1 * The PWM signal that controls the on / off of the switching element Q2 is D ul1 * is.

[0057] The switching elements Q3 and Q4 configure a V-phase leg (hereinafter referred to as a first V-phase leg) of the first inverter 18. That is, one end of a V-phase stator coil (V) is connected between the series-connected switching elements Q3 and Q4. The switching element Q3 is the upper arm of the first V-phase leg, and the switching element Q4 is the lower arm of the first V-phase leg. The PWM signal that controls the on / off of the switching element Q3 is D vu1 * The PWM signal that controls the on / off of the switching element Q4 is D vl1 * is.

[0058] Similarly, switching elements Q5 and Q6 configure a W-phase leg (hereinafter referred to as a first W-phase leg) of first inverter 18. That is, one end of a W-phase stator coil (W) is connected between series-connected switching elements Q5 and Q6. Switching element Q5 is the upper arm of the first W-phase leg, and switching element Q6 is the lower arm of the first W-phase leg. A PWM signal that controls the on / off of switching element Q5 is D wu1 * The PWM signal that controls the on / off of the switching element Q6 is D wl1 * is.

[0059] Switching elements Q7 to Q8 that form the second inverter 19 12 As described below, the switching elements Q1 to Q6 of the first inverter 18 configure legs for the UV phases.

[0060] The switching elements Q7 and Q8 configure a U-phase leg (hereinafter referred to as a second U-phase leg) of the second inverter 19. That is, the other end of the U-phase stator coil (U) is connected between the series-connected switching elements Q7 and Q8. The switching element Q7 is the upper arm of the second U-phase leg, and the switching element Q8 is the lower arm of the second U-phase leg. The PWM signals that control the on / off of the switching elements Q7 and Q8 are respectively D uu2 * ,D ul2 * is.

[0061] Switching elements Q9, Q 10 The switching elements Q9 and Q1 form a V-phase leg (hereinafter referred to as a second V-phase leg) of the second inverter 19. That is, the switching elements Q1, Q2 connected in series 10 The other end of the V-phase stator coil (V) is connected between the switching element Q9 and the switching element Q10. 10 is the lower arm of the second V-phase leg. Switching elements Q9 and Q 10 The PWM signals that control the on / off of vu2 * ,D vl2 * is.

[0062] Similarly, switching element Q 11 ,Q 12 constitutes a W-phase leg (hereinafter referred to as a second W-phase leg) of the second inverter 19. That is, the series-connected switching element Q 11 ,Q 12 The other end of the W-phase stator coil (W) is connected between the switching element Q 11 is the upper arm of the second W-phase leg, and switching element Q 12 is the lower arm of the second W-phase leg. Switching element Q 11 ,Q 12 The PWM signals that control the on / off of wu2 * ,D wl2 * is.

[0063] 3 is an explanatory diagram showing PWM signals in the normal mode. In FIG. 3, for the U-phase leg (first U-phase leg) of the first inverter 18, the first duty command value Duty_U1 and the PWM signal D uu1 * ,D ul1 * The first duty command value Duty_VW1 for the first V-phase leg and the first W-phase leg, and the PWM signal D vu1 * ~D wl1 *The same applies to the second duty command value Duty_UVW2 for the second inverter 19 and the PWM signal D uu2 * ~D wl2 * The same is true for

[0064] 3, the first PWM control unit 33 calculates and updates the first duty command value Duty_U1 at every predetermined control period (τ). However, the first duty command value Duty_U1 calculated in a certain control period is reflected in the next control period. For example, the first duty command value Duty_U1 calculated in control period P1 is used in control period P2. Similarly, the first duty command value Duty_U1 calculated in control period P2 is used in control period P3, and the first duty command value Duty_U1 calculated in control period P3 is used in control period P4.

[0065] In principle, the first PWM signal generator 36 generates the PWM signal D when the carrier signal CS matches the first duty command value Duty_U1 calculated and updated as described above. uu1 * ,D ul1 * Also, the PWM signal D for the upper arm is switched on (ON) / off (OFF). uu1 * and the PWM signal D for the lower arm ul1 * are complementary. That is, the PWM signal D for the upper arm uu1 * When switching from ON to OFF, the PWM signal D ul1 * is switched from OFF to ON. Also, the PWM signal D for the lower arm ul1 * When switching from ON to OFF, the PWM signal D uu1 * can be switched from off to on.

[0066] However, in order to prevent the upper arm and the lower arm from being turned on simultaneously and causing a through current to flow through the first U-phase leg, the first PWM signal generator 36 provides a dead time DT. The dead time DT is the time when the PWM signal D uu1 * and the PWM signal D for the lower arm ul1 * In this embodiment, the first PWM signal generator 36 inserts a dead time DT into the PWM signal of the arm that is to be switched from off to on. That is, when the upper arm is switched on, the PWM signal D uu1 * Similarly, when the lower arm is switched on, the timing to turn on the PWM signal D ul1 * The timing at which the switch is turned on is delayed by the dead time DT.

[0067] Fig. 4 is a block diagram showing the configuration of a portion related to ASC control in the PWM control unit 24. As shown in Fig. 4, the first PWM control unit 33 and the second PWM control unit 34 of the PWM control unit 24 include an up / down switching signal generation unit 41, a timing adjustment processing unit 42, and an ASC switching processing unit 43.

[0068] The upper / lower switching signal generator 41 generates an ASC switching signal (hereinafter referred to as a reference ASC switching signal S) that indicates a reference timing for switching between the upper short-circuit control and the lower short-circuit control. STD That is, the up / down switching signal generating unit 41 generates the reference ASC switching signal S STD This sets the reference timing for switching between the upper-side short-circuit control and the lower-side short-circuit control.

[0069] The upper-side short-circuit control is ASC control that turns on the upper arms of the first inverter 18 and the second inverter 19 and turns off the lower arms of the first inverter 18 and the second inverter 19, thereby forming a short circuit in the first inverter 18, the rotating electric machine 10, and the second inverter 19. In the upper-side short-circuit control, all of the upper arms of the first U-phase leg, the first V-phase leg, the first W-phase leg, the second U-phase leg, the second V-phase leg, and the second W-phase leg are turned on and all of the lower arms are turned off. The lower-side short-circuit control is ASC control that turns off the upper arms of the first inverter 18 and the second inverter 19 and turns on the lower arms of the first inverter 18 and the second inverter 19, thereby forming a short circuit in the first inverter 18, the rotating electric machine 10, and the second inverter 19. In lower-side short-circuit control, all upper arms of the first U-phase leg, first V-phase leg, first W-phase leg, second U-phase leg, second V-phase leg, and second W-phase leg are turned off, and all lower arms are turned on.

[0070] Reference ASC switching signal S STD is expressed by "ON" to specify the upper short circuit control or "OFF" to specify the lower short circuit control. The execution time t ASC (See Figure 5) are common in principle. The execution time t ASC is set to a time that is at least sufficiently longer than the control period τ. The execution time t ASC is determined by fitting based on experiments, simulations, etc.

[0071] The timing adjustment processing unit 42 calculates the phase current i u ,i v ,i w Then, the timing adjustment processing unit 42 acquires the acquired phase current i u ,i v ,i wBased on this, the timing adjustment processing unit 42 generates a final ASC switching signal with the timing adjusted (corrected) for each UVW phase. As a result, when switching between the upper side short-circuit control and the lower side short-circuit control, the timing adjustment processing unit 42 switches the first inverter 18 and the second inverter 19 sequentially at different timings for each UVW phase.

[0072] The final ASC switching signal generated by the timing adjustment processing unit 42 is the U-phase ASC switching signal S U , V-phase ASC switching signal S V , and W-phase ASC switching signal S W U-phase ASC switching signal S U indicates the timing at which the U-phase arms (Q1, Q2, Q7, Q8) of the first inverter 18 and the second inverter 19 should be switched. V are the V-phase arms (Q3, Q4, Q9, Q 10 ) represents the timing at which the W-phase ASC switching signal S W are the W-phase arms (Q5, Q6, Q7) of the first inverter 18 and the second inverter 19. 11 ,Q 12 ) represents the timing at which the final ASC switching signal for each phase (hereinafter referred to as the individual phase ASC switching signal S U ,S V ,S W ) is the phase current i u ,i v ,i w Based on the reference ASC switching signal S STD is generated by correcting

[0073] Specifically, the timing adjustment processing unit 42 adjusts the phase current i u ,i v ,i w The magnitude (absolute value |i u |,|i v |,|i w Based on the reference ASC switching signal S STDThe ASC switching signal S for each phase delays the timing at which the first inverter 18 and the second inverter 19 are actually switched on relative to the reference timing indicated by the U ,S V ,S W Generate.

[0074] In particular, in this embodiment, the timing adjustment processing unit 42 adjusts the phase current i u ,i v ,i w The ASC switching signal S for each phase is adjusted so that switching occurs at the timing when U ,S V ,S W The timing adjustment processing unit 42 generates the phase current i u ,i v ,i w The timing when becomes zero is, for example, the phase current i u ,i v ,i w It can be determined whether the magnitude of |i u From the state |>ε to |i u When |≦ε, the timing adjustment processing unit 42 adjusts the U-phase current i u is determined to be zero.

[0075] In the following, as shown above, the phase current i u ,i v ,i w The determination of whether the magnitude of the phase current i satisfies a predetermined condition is called phase current determination. u ,i v ,i w The determination of the timing when the phase current i becomes zero is called zero-crossing determination. The current threshold value ε used for zero-crossing determination is determined in advance by adaptation based on experiments, simulations, etc. In the following, u ,i v ,i w Based on the reference ASC switching signal S STD and adjusts (corrects) the ASC switching signal S for each phase. U ,S V ,S WThe process of generating this is called timing adjustment process.

[0076] FIG. 5 shows the reference ASC switching signal S STD , phase current i u ,i v ,i w , and each phase ASC switching signal S U ,S V ,S W 10 is a time chart showing an example of the above.

[0077] As shown in Figure 5, the reference ASC switching signal S STD is the phase current i u ,i v ,i w Regardless of the predetermined execution time t ASC The upper-side short-circuit control and the lower-side short-circuit control are alternately executed every time the reference ASC switching signal S STD is the phase current i u ,i v ,i w is not regarded as zero. STD Next, the on / off switching timing indicated by the phase current i u ,i v ,i w Each phase ASC switching signal S is delayed until it can be considered as zero. U ,S V ,S W Then, the phase current i u ,i v ,i w The periods are shifted from each other by 1 / 3 period. Therefore, when switching between the upper side short circuit control and the lower side short circuit control, the switching of the first inverter 18 and the second inverter 19 is performed with a delay for each phase.

[0078] In the example shown in FIG. 5, the reference ASC switching signal S STD When switching from off to on and switching from low-side short circuit control to high-side short circuit control, the switching delay of the U-phase arm (Q1, Q2, Q7, Q8) is δ U1and the V-phase arm (Q3, Q4, Q9, Q 10 ) switching delay is δ V1 and the W-phase arm (Q5, Q6, Q 11 ,Q 12 ) switching delay is δ W1 And, δ U1 >δ V1 >δ W1 Therefore, the switching from the lower side short circuit control to the upper side short circuit control is completed by switching the W-phase arm, the V-phase arm, and the U-phase arm in this order. Similarly, the reference ASC switching signal S STD When switching from on to off and switching from upper short circuit control to lower short circuit control, the switching delay of the U-phase arm (Q1, Q2, Q7, Q8) is δ U2 and the V-phase arm (Q3, Q4, Q9, Q 10 ) switching delay is δ V2 and the W-phase arm (Q5, Q6, Q 11 ,Q 12 ) switching delay is δ W2 And, δ U2 >δ V2 >δ W2 Therefore, the switch from the upper side short-circuit control to the lower side short-circuit control is also completed by switching the W-phase arm, the V-phase arm, and the U-phase arm in this order.

[0079] However, the reference ASC switching signal S STD The timing of switching and the phase current i u ,i v ,i w Depending on the magnitude relationship of the reference ASC switching signal S, the magnitude relationship of the switching delay between the phases and the switching order may differ from the above. STD The timing of switching and the phase current i u ,i v ,i w Depending on the relationship between the magnitudes of δ and δ, the magnitude of the switching delay may differ when switching from the lower-side short-circuit control to the upper-side short-circuit control and when switching from the upper-side short-circuit control to the lower-side short-circuit control. For example, in the example shown in FIG. 5, δU1 =δ U2 However, δ U1 >δ U2 In some cases, δ U1 <δ U2 The same applies to the V and W phases.

[0080] In this embodiment, the execution time t ASC is the phase current i u ,i v ,i w Therefore, the execution time t ASC Phase current i contained in u ,i v ,i w The increase or decrease in the number of fluctuations of the phase current i can be practically ignored. u ,i v ,i w Therefore, in a time interval of about the control period τ, the phase current i u ,i v ,i w The fluctuations in the

[0081] In addition, in this embodiment, the current flowing from the first inverter 18 through the stator coils (U, V, W) to the second inverter 19 is defined as positive. That is, for example, the U-phase current i u is positive U-phase current i u and the U-phase current i that flows from the second U-phase leg through the U-phase stator coil (U) to the first U-phase leg u is negative U-phase current i u V-phase current i v , and W-phase current i w The same is true for .

[0082] The ASC switching processing unit 43 (see FIG. 4) switches the duty command value generation mode S mode When the ASC mode is selected, the ASC switching signal S for each phase is set according to Table 2 below. U ,S V ,SW As a result, the ASC switching processing unit 43 switches between the upper side short-circuit control and the lower side short-circuit control by sequentially switching the first inverter 18 and the second inverter 19 for each phase.

[0083] [Table 2]

[0084] Specifically, each phase ASC switching signal S U ,S V ,S W When the ASC switching signal S is ON, the ASC switching processing unit 43 sets the duty command value (Duty_UVW1, Duty_UVW2) to 100%. U ,S V ,S W When the ASC switching signal S is OFF, the ASC switching processing unit 43 sets the duty command values (Duty_UVW1, Duty_UVW2) to 0%. Therefore, in the ASC mode of this embodiment, the duty command values (Duty_UVW1, Duty_UVW2) are set to the respective phases of the ASC switching signal S. U ,S V ,S W Depending on the

[0085] As mentioned above, the ASC switching signal S U ,S V ,S W have different timings at which they switch on / off, the timing at which the duty command values (Duty_UVW1, Duty_UVW2) switch differs for each phase. That is, the timing at which Duty_U1 and Duty_U2 switch, the timing at which Duty_V1 and Duty_V2 switch, and the timing at which Duty_W1 and Duty_W2 switch are all different.

[0086] On the other hand, each phase ASC switching signal S U ,S V ,SW is common to the first inverter 18 and the second inverter 19. Therefore, in this embodiment, the timing at which Duty_U1 switches and the timing at which Duty_U2 switches are the same. Similarly, the timing at which Duty_V1 switches and the timing at which Duty_V2 switches are the same, and the timing at which Duty_W1 switches and the timing at which Duty_W2 switches are the same. However, a dead time DT is provided between the paired upper arm and lower arm.

[0087] That is, in this embodiment, when switching between the upper side short circuit control and the lower side short circuit control, the upper arms (Q1, Q3, Q5, Q7, Q9, Q 11 ) are simultaneously switched, and the lower arms (Q2, Q4, Q6, Q8, Q 10 ,Q 12 ) are switched simultaneously. A dead time DT is inserted between the switching of each upper arm and the switching of each lower arm.

[0088] The operation of the ASC control performed in the electric vehicle 100 configured as described above will be described below.

[0089] 6 is a flowchart relating to the ASC control. As shown in FIG. 6, in step S10, the controller 13 controls the phase current i u ,i v ,i w , DC voltage V dc , and the electrical angle θ. The controller 13 also calculates the rotation speed N of the rotating electric machine 10 based on the electrical angle θ using the rotation speed calculation unit 27. In step S11, the abnormality detection unit 28 detects whether or not there is an abnormality in the system that drives the rotating electric machine 10, such as over-rotation or over-current.

[0090] If no abnormality is detected in step S11, the process proceeds to step S12, where the PWM control unit 24 calculates duty command values Duty_UVW1, Duty_UVW2 in the normal mode for driving the rotating electric machine 10. Then, the PWM signal generator 25 generates the PWM signal D in accordance with the duty command values Duty_UVW1, Duty_UVW2 in the normal mode. uu1 * ~D wl1 * ,D uu2 * ~D wl2 * and drives the rotating electric machine 10. As a result, the rotating electric machine 10 generates a torque command value T * The rotation is controlled so as to output a torque according to the

[0091] On the other hand, if an abnormality such as over-rotation or over-current is detected in step S11, the abnormality detection unit 28 outputs a relay cut signal S RC In step S13, the output determination unit 35 determines whether the absolute value |N| of the rotation speed N is greater than or equal to the rotation speed upper limit value N MAX Compare with.

[0092] In step S13, the absolute value |N| of the rotation speed N is equal to the rotation speed upper limit value N MAX If it is equal to or less than this, the process proceeds to step S14, and the output determination unit 35 determines whether the gate permission signal S GP is set to "prohibited." Therefore, ASC control is not performed. Even if some abnormality occurs during operation of the rotating electrical machine 10, the absolute value |N| of the rotation speed N is set to "prohibited." MAX This is because when the voltage induced in the rotary electric machine 10 is less than this value, the system can be shut down without performing ASC control.

[0093] On the other hand, in step S13, the absolute value |N| of the rotation speed N is equal to or exceeds the rotation speed upper limit value N MAXSpecifically, the process proceeds to step S15, where the upper / lower switching signal generator 41 generates a reference ASC switching signal S for switching between the upper short-circuit control and the lower short-circuit control. STD In step S16, the timing adjustment processing unit 42 performs a phase current determination. The phase current determination performed in this embodiment is a zero-cross determination. That is, in step S16, the timing adjustment processing unit 42 generates a phase current i u ,i v ,i w Then, in step S17, the timing adjustment processing unit 42 determines the timing at which the magnitude of the reference ASC switching signal S can be regarded as substantially zero. STD The on / off switching timing indicated by the phase current i u ,i v ,i w Each phase ASC switching signal S is delayed until it can be considered as zero. U ,S V ,S W Generate.

[0094] In this way, the ASC switching signal S for each phase U ,S V ,S W When the gate enable signal S is generated, the process proceeds to step S18. In step S18, the ASC switching processing unit 43 generates duty command values (Duty_UVW1, Duty_UVW2) for the ASC. In step S19, the output determination unit 35 determines whether the gate enable signal S GP is set to "Permitted". This allows ASC control to be executed. In this ASC control, upper side short circuit control and lower side short circuit control are periodically switched. When switching between upper side short circuit control and lower side short circuit control, the first inverter 18 and the second inverter 19 are switched at different timings for each of the UVW phases.

[0095] 7 is a block diagram showing an example of a PWM signal in the ASC mode. In FIG. 7, the PWM signal D for the U phase of the first inverter 18 is uu1 * ,D ul1 *and the PWM signal D for the U phase of the second inverter 19. uu2 * ,D ul2 * In addition, in FIG. 7, the reference ASC switching signal S STD After switching from ON to OFF, at time t0 when control period P1 switches to control period P2, the U-phase current i u becomes substantially zero, and the U-phase ASC switching signal S U changes from on to off.

[0096] As shown in FIG. 7, at time t0, the U-phase ASC switching signal S U When the PWM signal D changes from ON to OFF, the ASC switching processing unit 43 switches the duty command values (Duty_U1, Duty_U2) from 100% to 0% in the control period P2. uu1 * ,D ul1 * ,D uu2 * ,D ul2 * This is reflected in the generation of

[0097] Therefore, the PWM signal D for the U-phase upper arm (Q1) of the first inverter 18 uu1 * The PWM signal D for the U-phase upper arm (Q7) of the second inverter 19 is switched from ON to OFF at time t1 when the control period P2 transitions to the control period P3. uu2 * Also, at time t1, the switch 100 switches from ON to OFF.

[0098] On the other hand, as described above, the PWM signal generator 25 (first PWM signal generator 36 and second PWM signal generator 37) inserts a dead time DT into the PWM signal that switches from OFF to ON. ul1 *The PWM signal D for the U-phase lower arm (Q8) of the second inverter 19 is switched from OFF to ON at time t2 when the dead time DT has elapsed since time t1. ul2 * Also, at time t2, the power supply 11 is switched from OFF to ON.

[0099] As mentioned above, in Figure 7, the PWM signal D uu1 * ,D ul1 * ,D uu2 * ,D ul2 * However, the same applies to the V-phase and W-phase. However, the ASC switching signal S U ,S V ,S W is the phase current i u ,i v ,i w Therefore, the PWM signals D of the V and W phases are switched at the timing when they can be considered to be zero. vu1 * ~D wl1 * ,D vu2 * ~D wl2 * The timing of switching is U-phase PWM signal D uu1 * ,D ul1 * ,D uu2 * ,D ul2 * The timing of the switch is different.

[0100] In the following, when switching between the upper short-circuit control and the lower short-circuit control, in particular, the phase current i u ,i v ,i w The effect of switching the first inverter 18 and the second inverter 19 at timings when each of the voltages can be considered to be zero will be described below.

[0101] 8A and 8B are diagrams illustrating the relationship between the phase current and the timing of switching the first inverter 18 and the second inverter 19. Fig. 8A shows a comparative example, and Fig. 8B shows this embodiment.

[0102] In the comparative example, the phase current i u ,i v ,i w In this example, the first inverter 18 and the second inverter 19 are switched on and off at the timing when the U-phase current i u When the U-phase ASC switching signal S U The operation of the comparative example will be described using an example in which the U-phase current i u is positive (i u >0) and V-phase current i v and W-phase current i w is negative (i v ,i w <0), the U-phase arms (Q1, Q2, Q7, Q8) of the first inverter 18 and the second inverter 19 are switched.

[0103] Also, as shown in FIG. 8A, in the comparative example, the U-phase ASC switching signal S U When the V-phase ASC switching signal S V and W-phase ASC switching signal S W Therefore, the switching of the U-phase arm (Q1, Q2, Q7, Q8) is performed by the upper arms (Q3, Q5, Q9, Q 11 ) are still on, and the lower arms (Q4, Q6, Q 10 ,Q 12 ) is still off.

[0104] On the other hand, in this embodiment, as described above, the phase current i u ,i v ,i wThe first inverter 18 and the second inverter 19 are switched on and off at the timing when the U-phase current i u When the U-phase ASC switching signal S becomes zero during the process of changing from negative to positive, U The operation of this embodiment will be described using as an example a scene in which the U-phase current i u is zero (i u =0), and the V-phase current i v is negative (iv<0) and the W-phase current i w is positive (i w >0), the U-phase arms (Q1, Q2, Q7, Q8) of the first inverter 18 and the second inverter 19 are switched.

[0105] Also, as shown in FIG. 8B, in this embodiment, the U-phase ASC switching signal S U When the V-phase ASC switching signal S V and W-phase ASC switching signal S W Therefore, the switching of the U-phase arm (Q1, Q2, Q7, Q8) is performed by the upper arms (Q3, Q5, Q9, Q 11 ) are already off, and the lower arms (Q4, Q6, Q 10 ,Q 12 ) is already on.

[0106] FIG. 9 shows the phase current i u ,i v ,i w (Especially U-phase current i u ) is an explanatory diagram showing the transition of

[0107] As shown in FIG. 9A, in the comparative example, the U-phase ASC switching signal S U When the U-phase arms (Q1, Q2, Q7, Q8) of the first inverter 18 and the second inverter 19 are switched from ON to OFF, the U-phase current i u is positive (iu >0), V phase current i v and W-phase current i w is negative (i v ,i w <0). Also, the upper arms of each UVW phase (Q1, Q3, Q5, Q7, Q9, Q 11 ) are all on, and the lower arms (Q2, Q4, Q6, Q8, Q 10 ,Q 12 ) are all off.

[0108] Therefore, the U-phase current i u flows from the U-phase upper arm (Q1) of the first inverter 18 to the U-phase stator coil (U), and circulates through the freewheel diode of the U-phase upper arm (Q7) of the second inverter 19. v flows from the V-phase upper arm (Q9) of the second inverter 19 to the V-phase stator coil (V), and circulates through the freewheel diode of the V-phase upper arm (Q3) of the first inverter 18. Then, the W-phase current i w is the upper arm (Q 11 ) into the W-phase stator coil (W), and circulates through the freewheel diode of the W-phase upper arm (Q5) of the first inverter 18. At this time, the phase current i u ,i v ,i w is consumed by circulating through the first inverter 18, the rotating electrical machine 10, and the second inverter 19. In addition, the DC current i dc is zero (i dc = 0). In other words, the smoothing capacitor 39 is neither charged nor discharged. Note that the direction in which the smoothing capacitor 39 is discharged is the direction of the DC current i dc , and the direction in which the smoothing capacitor 39 is charged is the direction in which the DC current i dc is in the negative direction.

[0109] In this state, the U-phase current i u reaches its peak, and the U-phase ASC switching signal S UWhen the V-phase current i changes from ON to OFF, first, as shown in FIG. 9B, the U-phase upper arms (Q1, Q7) of the first inverter 18 and the second inverter 19 are switched from ON to OFF. At this time, the V-phase current i v and W-phase current i w There is no change in the flow of U-phase current i u Specifically, as shown in Figure 9(B), the flow of U-phase current i u flows from the U-phase stator coil (U) through the freewheel diode of the U-phase upper arm (Q7) of the second inverter 19 to the smoothing capacitor 39, and then circulates through the freewheel diode of the U-phase lower arm (Q2) of the first inverter 18. Therefore, the DC current i dc is negative (i dc =-|i u That is, the V-phase current i generated by the induced voltage of the rotating electrical machine 10 v and W-phase current i w is consumed by circulating through the first inverter 18, the rotating electrical machine 10, and the second inverter 19, but the smoothing capacitor 39 does not u is charged by

[0110] Then, after the U-phase upper arms (Q1, Q7) of the first inverter 18 and the second inverter 19 are switched from on to off, when the dead time DT has elapsed, the U-phase lower arms (Q2, Q8) of the first inverter 18 and the second inverter 19 are switched from off to on, as shown in FIG. 9(C). At this time, the V-phase current i v and W-phase current i w There is no change in the flow of U-phase current i u The flow of U-phase current i changes again as shown in Figure 9(C). u flows from the freewheel diode of the U-phase lower arm (Q2) of the first inverter 18 to the U-phase stator coil (U), and then circulates through the U-phase lower arm (Q8) of the second inverter 19. Therefore, the DC current i dc is zero (i dc = 0). Therefore, the phase current i generated by the induced voltage of the rotating electrical machine 10 u ,iv ,i w is consumed by circulating through the first inverter 18, the rotating electric machine 10, and the second inverter 19. Furthermore, the smoothing capacitor 39 is neither charged nor discharged.

[0111] Here, a scene is shown in which the U-phase arms of the first inverter 18 and the second inverter 19 are switched in order to switch from upper side short-circuit control to lower side short-circuit control, but the same applies to a scene in which the V-phase arms and the W-phase arms are switched. The same also applies to a scene in which the lower side short-circuit control is switched to upper side short-circuit control.

[0112] Therefore, in the comparative example, when switching between the upper side short circuit control and the lower side short circuit control, the smoothing capacitor 39 is charged. Therefore, in the comparative example, the capacitance of the smoothing capacitor 39 and the phase current i u ,i v ,i w Depending on the magnitude of the voltage, there is a risk that the smoothing capacitor 39 may be damaged by overcharging or the like when switching between the upper-side short-circuit control and the lower-side short-circuit control.

[0113] FIG. 10 shows the phase current i u ,i v ,i w (Especially U-phase current i u ) is an explanatory diagram showing the transition of

[0114] As shown in FIG. 10(A), in this embodiment, the U-phase ASC switching signal S U Immediately before switching from on to off, the U-phase current i u is negative (i u <0), V phase current i v is negative (iv<0), W-phase current i w is positive (i w >0). Also, the U-phase upper arm (Q1, Q7) is on, and the U-phase lower arm (Q2, Q8) is off. On the other hand, the V-phase upper arm (Q3, Q9) and the W-phase upper arm (Q5, Q 11 ) is off, and the V-phase lower arm (Q4, Q 10) and W-phase lower arm (Q6, Q 12 ) is on. Therefore, the U-phase current i u flows from the U-phase upper arm (Q7) of the second inverter 19 to the U-phase stator coil (U), and circulates through the freewheel diode of the U-phase upper arm (Q1) of the first inverter 18. v is the V-phase lower arm (Q 10 ) into the V-phase stator coil (V), and circulates through the V-phase lower arm (Q3) of the first inverter 18. Then, the W-phase current i w flows from the freewheel diode of the W-phase lower arm (Q6) of the first inverter 18 to the W-phase stator coil (W), and 10 As a result, the phase current i generated by the induced voltage of the rotating electric machine 10 u ,i v ,i w is consumed by circulating through the first inverter 18, the rotating electrical machine 10, and the second inverter 19. In addition, the DC current i dc is zero (i dc =0). Therefore, the smoothing capacitor 39 is neither charged nor discharged.

[0115] And, U-phase current i u When becomes zero, (i u =0), as shown in Figure 10(B), the V-phase current i v and W-phase current i w The flow of U-phase current i u Therefore, the phase current i generated by the induced voltage of the rotating electrical machine 10 u ,i v ,i w is consumed by circulating through the first inverter 18, the rotating electric machine 10, and the second inverter 19, and the smoothing capacitor 39 is neither charged nor discharged.

[0116] Also, U-phase current i u becomes zero, the U phase ASC switching signal S UWhen changes from on to off, first, as shown in FIG. 10(C), the U-phase upper arms (Q1, Q7) of the first inverter 18 and the second inverter 19 are switched from on to off.

[0117] At this time, the U-phase current i u is a positive significant value (i u >0), the U-phase current i u flows into the smoothing capacitor 39 through the freewheeling diode of the U-phase upper arm (Q7) of the second inverter 19. Also, when the U-phase current iu becomes a negative significant value (i u <0), the U-phase current i u flows into the smoothing capacitor 39 through the freewheeling diode of the U-phase upper arm (Q1) of the first inverter 18. Therefore, the U-phase current i u When is a positive or negative significant value, as shown in FIG. 9(C), when the U-phase upper arms (Q1, Q7) of the first inverter 18 and the second inverter 19 are switched from on to off, the smoothing capacitor 39 is charged.

[0118] However, in this embodiment, the U-phase current i u is zero (i u =0). Therefore, the DC current i dc is also kept at zero (i dc =-|i u |=0). That is, in this embodiment, the smoothing capacitor 39 is neither charged nor discharged at the timing when the U-phase upper arms (Q1, Q7) of the first inverter 18 and the second inverter 19 are switched from on to off. Note that the V-phase current i v and W-phase current i w is consumed by circulating through the first inverter 18, the rotating electric machine 10, and the second inverter 19.

[0119] Then, after the U-phase upper arms (Q1, Q7) of the first inverter 18 and the second inverter 19 are switched from on to off, when the dead time DT has elapsed, the U-phase lower arms (Q2, Q8) of the first inverter 18 and the second inverter 19 are switched from off to on, as shown in FIG. 10(D). However, the U-phase current i u is zero (i u =0). Therefore, the DC current i dc is maintained at zero, and the smoothing capacitor 39 is neither charged nor discharged. v and W-phase current i w is consumed by circulating through the first inverter 18, the rotating electric machine 10, and the second inverter 19.

[0120] Then, the U-phase current i u When becomes a positive significant value, the U-phase current i u flows from the freewheel diode of the U-phase lower arm (Q2) of the first inverter 18 to the U-phase stator coil (U), and circulates through the U-phase lower arm (Q8) of the second inverter 19. Therefore, the phase current i u ,i v ,i w is consumed by circulating through the first inverter 18, the rotating electric machine 10, and the second inverter 19. In addition, the DC current i dc is maintained at zero and the smoothing capacitor 39 is neither charged nor discharged.

[0121] Here, a scene is shown in which the U-phase arms of the first inverter 18 and the second inverter 19 are switched in order to switch from upper side short-circuit control to lower side short-circuit control, but the same applies to a scene in which the V-phase arms and the W-phase arms are switched. The same also applies to a scene in which the lower side short-circuit control is switched to upper side short-circuit control.

[0122] Therefore, in this embodiment, the phase current i u ,i v ,i wWhen the first inverter 18 and the second inverter 19 are switched on for each phase at the timing when the phase current i generated by the induced voltage of the rotating electric machine 10 is zero, u ,i v ,i w Thus, switching between upper side short circuit control and lower side short circuit control is performed without charging the smoothing capacitor 39. In other words, when switching between upper side short circuit control and lower side short circuit control, the smoothing capacitor 39 is protected and is not damaged by overcharging or the like.

[0123] [Second embodiment] In the first embodiment, when switching between the upper side short circuit control and the lower side short circuit control, the phase current i u ,i v ,i w The first inverter 18 and the second inverter 19 are switched for each phase at the timing when the phase current i u ,i v ,i w When the first inverter 18 and the second inverter 19 are switched at a timing when the phase current i u ,i v ,i w An example will be described in which the first inverter 18 and the second inverter 19 are switched for each phase at the timing when is a significant value.

[0124] The general functional block configuration of the controller 13 in the second embodiment is the same as that in the first embodiment. However, the specific functions (calculation contents, etc.) of the output determination unit 35, timing adjustment processing unit 42, and ASC switching processing unit 43 are different from those in the first embodiment as follows.

[0125] The output determination unit 35 (see FIG. 1) of the second embodiment determines whether the status signal S state , the absolute value of the rotation speed N |N|, and the DC voltage V dc Based on this, the gate enable signal SGP and duty command value generation mode S mode That is, compared to the first embodiment, the output determination unit 35 of the second embodiment sets or changes the DC voltage V dc Also see the gate enable signal S GP and duty command value generation mode S mode Specifically, the output determination unit 35 of the second embodiment sets the gate enable signal S according to Table 3 below. GP and duty command value generation mode S mode Set or change the

[0126] [Table 3]

[0127] As shown in Table 3, the status signal S sate indicates "normal" and the rotating electrical machine 10 can be driven without any problems, the PWM control unit 24 calculates the absolute value |N| of the rotation speed N and the DC voltage V dc Regardless of the gate enable signal S GP is set to "Permitted" and the duty command value generation mode S mode is set to the normal mode, which is the same as in the first embodiment.

[0128] Status signal S state indicates "abnormal" and there is a problem in driving the rotating electric machine 10, the output determination unit 35 of the second embodiment determines the absolute value |N| of the rotation speed N and the DC voltage V dc Based on this, the gate enable signal S GP and duty command value generation mode S mode Set.

[0129] Specifically, the status signal S state is "abnormal" and the absolute value of the rotation speed N |N| is greater than the rotation speed upper limit N MAX When |N|>N MAX ), the output determination unit 35 outputs the gate permission signal S GP is set to "Permitted" and the duty command value generation mode S modeThe output determination unit 35 of the second embodiment sets the DC voltage V dc According to the above, the duty command value generation mode S mode to either the first ASC mode (ASC1) or the second ASC mode (ASC2).

[0130] As shown in Table 3, the first ASC mode (ASC1) is dc is the voltage threshold V th The second ASC mode (ASC2) is selected when the DC voltage V dc is the voltage threshold V th This is the ASC mode that is selected when the DC voltage V dc Voltage threshold V th is determined in advance by adaptation based on experiments, simulations, etc. th represents the voltage of the smoothing capacitor 39 that should be maintained in anticipation of restarting the system (recharging of the smoothing capacitor 39) after the execution of ASC control.

[0131] As shown in Table 3, the status signal S state is "abnormal" and the absolute value of the rotation speed N |N| is greater than the rotation speed upper limit N MAX When |N|≦N MAX ), the output determination unit 35 determines the DC voltage V dc Regardless of this, the gate enable signal S GP is set to "prohibited." In this case, the first PWM control unit 33 and the second PWM control unit 34 do not generate duty command values (Duty_UVW1, Duty_UVW2). Therefore, the rotary electric machine 10 is stopped without performing ASC control. This is the same as in the first embodiment.

[0132] The timing adjustment processing unit 42 (see FIG. 4) of the second embodiment calculates the phase current i u ,i v ,i w Then, the timing adjustment processing unit 42 acquires the acquired phase current i u ,i v,i w Based on this, the timing of each UVW phase is adjusted (corrected) and the ASC switching signal S U ,S V ,S W As a result, when switching between the upper side short circuit control and the lower side short circuit control, the timing adjustment processing unit 42 switches the first inverter 18 and the second inverter 19 sequentially at different timings for the UVW phases. u ,i v ,i w The magnitude (absolute value |i u |,|i v |,|i w Based on the reference ASC switching signal S STD The ASC switching signal S for each phase delays the timing at which the first inverter 18 and the second inverter 19 are actually switched on relative to the reference timing indicated by the U ,S V ,S W These general functions are the same as those in the first embodiment.

[0133] However, the timing adjustment processing unit 42 of the second embodiment adjusts the phase current i u ,i v ,i w The magnitude (absolute value |i u |,|i v |,|i w |) to a predetermined threshold (hereinafter, the current threshold i th Then, the timing adjustment processing unit 42 sets the phase current i u ,i v ,i w The magnitude of the current threshold i th The ASC switching signal S for each phase is adjusted so that switching occurs at the above timing. U ,S V ,S W Generate the current threshold i th is the phase current i u ,i v ,i wis a reference value for determining whether or not has a magnitude (significance value) that cannot be considered to be zero, and is determined in advance by adaptation based on, for example, experiments or simulations.

[0134] In this embodiment, for convenience, the current threshold i th is essentially the phase current i u ,i v ,i w Therefore, the timing adjustment processing unit 42 determines the peak (maximum value) of the U-phase current i u is the current threshold i th When the value is greater than or equal to (|i u |≧i th ), U phase current i u It is determined that the phase current i has substantially reached its peak. u ,i v ,i w Therefore, simply put, the timing adjustment processing unit 42 of the second embodiment differs from the first embodiment (zero-crossing determination) in that it performs phase current determination by peak determination.

[0135] FIG. 11 shows the reference ASC switching signal S STD , phase current i u ,i v ,i w , and each phase ASC switching signal S U ,S V ,S W 11 is a time chart showing an example of the reference ASC switching signal S STD The on / off of the phase current i u ,i v ,i w Therefore, the timing adjustment processing unit 42 of the second embodiment determines the reference ASC switching signal S STD Next, the on / off switching timing indicated by the phase current i u ,i v ,i w The magnitude of the current threshold i thThe ASC switching signal S for each phase is delayed until it reaches a peak. U ,S V ,S W As a result, when switching between the upper side short circuit control and the lower side short circuit control, the switching of the first inverter 18 and the second inverter 19 is delayed for each phase.

[0136] In the example shown in FIG. 11, the reference ASC switching signal S STD When switching from off to on and switching from low-side short circuit control to high-side short circuit control, the switching delay of the U-phase arm (Q1, Q2, Q7, Q8) is δ U1 and the V-phase arm (Q3, Q4, Q9, Q 10 ) switching delay is δ V1 and the W-phase arm (Q5, Q6, Q 11 ,Q 12 ) switching delay is δ W1 Here, δ W1 >δ U1 >δ V1 = 0. Therefore, the switching from the lower side short circuit control to the upper side short circuit control is completed by switching the V-phase arm, the U-phase arm, and the W-phase arm in this order. Similarly, the reference ASC switching signal S STD When switching from on to off and switching from upper short circuit control to lower short circuit control, the switching delay of the U-phase arm (Q1, Q2, Q7, Q8) is δ U2 and the V-phase arm (Q3, Q4, Q9, Q 10 ) switching delay is δ V2 and the W-phase arm (Q5, Q6, Q 11 ,Q 12 ) switching delay is δ W2 And, δ W2 >δ U2 >δ V2 = 0. Therefore, the switch from the upper side short-circuit control to the lower side short-circuit control is also completed by switching the V-phase arm, the U-phase arm, and the W-phase arm in this order.

[0137] However, the reference ASC switching signal SSTD The timing of switching and the phase current i u ,i v ,i w Depending on the magnitude relationship of the reference ASC switching signal S, the magnitude relationship of the switching delay between the phases and the switching order may differ from the above. STD The timing of switching and the phase current i u ,i v ,i w Depending on the relationship between the magnitudes of the switching delays, the magnitude of the switching delay may differ when switching from lower-side short-circuit control to upper-side short-circuit control and when switching from upper-side short-circuit control to lower-side short-circuit control. These are the same as in the first embodiment.

[0138] The ASC switching processing unit 43 (see FIG. 4) of the second embodiment switches between the duty command value generation mode S mode When the ASC mode is selected, the ASC switching signal S U ,S V ,S W The ASC mode duty command values (Duty_UVW1, Duty_UVW2) are generated according to the above. As a result, the ASC switching processing unit 43 switches between the upper side short-circuit control and the lower side short-circuit control by sequentially switching the first inverter 18 and the second inverter 19 for each phase.

[0139] In particular, the ASC switching processor 43 of the second embodiment switches one arm of either the first inverter 18 or the second inverter 19 relatively earlier, and switches the other arm relatively later. Specifically, the ASC switching processor 43 determines the current switching state (hereinafter referred to as the current switching state) and the phase current i u ,i v ,i w Based on the direction of the signal, the inverter that switches relatively earlier (hereinafter referred to as the leading inverter) and the inverter that switches relatively later (hereinafter referred to as the following inverter) are determined from the first inverter 18 and the second inverter 19.

[0140] [Table 4]

[0141] As shown in Table 4, in a scene where the upper arm is on (ON), the lower arm is off (OFF), and the control is switched from the upper short circuit control to the lower short circuit control, the phase current i u ,i v ,i w The inverter into which the phase current flows is referred to as the leading inverter, and the inverter that feeds the phase current into the rotating electrical machine 10 is referred to as the trailing inverter. For example, in a scene where the U-phase arm is switched to switch from the upper short-circuit control to the lower short-circuit control, the U-phase current i u is positive, and the U-phase current i u When current flows from the U-phase arm (Q1 or Q2) of the first inverter 18 through the U-phase stator coil (U) to the U-phase arm (Q7 or Q8) of the second inverter 19, the first inverter 18 becomes the trailing inverter and the second inverter 19 becomes the leading inverter with respect to U-phase switching.

[0142] Also, as shown in Table 4, in a scene where the upper arm is OFF and the lower arm is ON and the control is switched from the lower side short circuit control to the upper side short circuit control, the phase current i u ,i v ,i w The inverter into which the phase current flows is referred to as the trailing inverter, and the inverter that feeds the phase current into the rotating electrical machine 10 is referred to as the leading inverter. For example, in a scene where the U-phase arm is switched to switch from the lower side short circuit control to the upper side short circuit control, the U-phase current i u When is positive, the first inverter 18 is the leading inverter and the second inverter 19 is the trailing inverter with respect to the switching of the U phase.

[0143] As described above, when the leading arm and the trailing arm are determined, the ASC switching processing unit 43 determines the carrier signal CS and the ASC switching signal S for each phase according to Table 5 below. U ,S V ,S W , and duty command value generation mode Smode In response to this, the controller 100 calculates a duty command value for the preceding inverter (hereinafter referred to as a preceding duty command value Duty_1st) and a duty command value for the following inverter (hereinafter referred to as a following duty command value Duty_2nd).Then, these are output as duty command values (Duty_UVW1, Duty_UVW2) for the ASC mode.

[0144] [Table 5]

[0145] Specifically, duty command value generation mode S mode When the ASC mode is the first ASC mode (ASC1), the ASC switching processor 43 sets the leading duty command value Duty_1st and the following duty command value Duty_2nd to different values when switching between the upper side short circuit control and the lower side short circuit control. u ,i v ,i w The magnitude of the current threshold i th With respect to the previous initial state, a transition state is formed in which the switching of the other inverter (preceding inverter) of either the first inverter 18 or the second inverter 19 is started first while the state of either the first inverter 18 or the second inverter (subsequent inverter) is maintained in the same state as in the initial state. Furthermore, the ASC switching processing unit 43 starts switching of the subsequent inverter after a predetermined time has elapsed since the switching of the subsequent inverter was started first. Thereafter, when the switching of the subsequent inverter is completed, a final state is formed in which the on / off states of the arms of the preceding inverter and subsequent inverter are reversed from those in the initial state.

[0146] In particular, the ASC switching processing unit 43 forms a first transition state, a second transition state, and a third transition state as the transition states.

[0147] The first transition state is a state in which both the upper and lower arms of the preceding inverter are turned off, while the state of the succeeding inverter is maintained the same as the initial state.

[0148] The second transition state is a state in which the state of the subsequent inverter is maintained in the same state as in the initial state, while the on / off state of the arm of the preceding inverter is reversed with respect to the initial state.

[0149] The third transition state is a state in which the on / off states of the arms of the preceding inverter are maintained in reverse to the initial state, while both the upper and lower arms of the succeeding inverter are turned off.

[0150] As is clear from the calculation formula shown in Table 5, the delay time T delay (predetermined time) is the dead time DT and additional time T p is the sum of (T delay =DT+T p ), longer than the dead time DT. Additional time T P is predetermined by adaptation, for example, based on experiments or simulations.

[0151] As described above, the leading duty command value Duty_1st and the trailing duty command value Duty_2nd are determined by the rise or fall of the carrier signal CS and the change of the ASC switching signal S for each phase. U ,S V ,S W Therefore, as shown in Table 5 above, the ASC switching processing unit 43 changes the ASC switching signal S U ,S V ,S W Based on this, the preceding duty command value Duty_1st and the following duty command value Duty_2nd are calculated.

[0152] In addition, in Table 5, the preceding duty command value Duty_1st is set to 50%, but this is just an example. delay ), the preceding duty command value Duty_1st can be set to any value other than 50%.

[0153] In this way, in the first ASC mode (ASC1), the ASC switching processor 43 determines the magnitudes of the phase currents iu, iv, and iw (|i u |,|i v |,|i w |) is the current threshold i th In the phase where the above has occurred, the switching of one of the first inverter 18 and the second inverter 19 (the preceding inverter) is started first, and the switching of the one of the first inverter 18 and the second inverter 19 (the preceding inverter) is started after a predetermined time (T delay =DT+T p ) has elapsed, the other inverter (the succeeding inverter) of the first inverter 18 and the second inverter 19 starts switching.

[0154] In the second ASC mode (ASC2), the ASC switching processing unit 43 exceptionally sets the leading duty command value Duty_1st and the following duty command value Duty_2nd to be equal. In this embodiment, the leading duty command value Duty_1st and the following duty command value Duty_2nd in the second ASC mode (ASC2) are both 50%. That is, in the second ASC mode (ASC2), the delay time T in switching the first inverter 18 and the second inverter 19 is delay (predetermined time) is zero (T delay = 0) Therefore, in the second ASC mode, the first inverter 18 and the second inverter 19 are switched at the same timing. Note that the "same timing" here describes the relationship between the first inverter 18 and the second inverter 19, and in the relationship between the upper arm and the lower arm, the dead time DT is provided as described above even in the second ASC mode.

[0155] In the following, when switching between the upper side short circuit control and the lower side short circuit control, the phase current i u ,i v ,i w The operation when the first inverter 18 and the second inverter 19 are switched at timings when the respective voltages substantially reach their peaks will be described.

[0156] 12 is a flowchart of the ASC control according to the second embodiment. As shown in FIG. 12, in the second embodiment, the determination of the leading / trailing inverter and the delay time T delay Steps S21 to S23 for setting the phase current are inserted. Also, the phase current determination in step S16 is replaced with a peak determination. Therefore, in step S17, the ASC switching signal S for each phase is generated. U ,S V ,S W The specific contents of step S24 differ from those of the first embodiment. Furthermore, step S24, which determines the preceding inverter and the succeeding inverter, is inserted between step S17 and step S18. In step S18, the specific contents of the duty command values (Duty_UVW1, Duty_UVW2) to be generated change depending on whether the ASC control is executed in the first ASC mode (ASC1) or the second ASC mode (ASC2). The other steps S10 to S14 and S19 are the same as those of the first embodiment.

[0157] Step S21 is performed when the absolute value |N| of the rotation speed N in step S13 is equal to the rotation speed upper limit value N MAX In step S21, the output determination unit 35 determines whether the DC voltage V dc is the voltage threshold V th The ASC mode is determined by comparing the DC voltage V dc is the voltage threshold V th On the other hand, when the DC voltage V dc is the voltage threshold V th If:

[0158] In step S21, the DC voltage V dc is the voltage threshold V th When the ASC control in the first ASC mode (ASC1) is to be executed, the process proceeds to step S22. In step S22, the ASC switching processing unit 43 determines the relative delay time T delay The dead time DT and additional time T p Set to the sum of (T delay =DT+T p ).

[0159] On the other hand, in step S21, the DC voltage V dc is the voltage threshold V th When the ASC control in the second ASC mode (ASC2) is executed, the process proceeds to step S23. In step S23, the delay time T delay Set to zero (T delay =0).

[0160] In step S24, the ASC switching processing unit 43 detects the phase current i u ,i v ,i w That is, in step S24, the ASC switching processing unit 43 determines (judges) which arm of the first inverter 18 or the second inverter 19 is to be switched first.

[0161] When it is determined in step S24 that the first inverter 18 is the preceding inverter and the second inverter 19 is the following inverter, the ASC switching processing unit 43 calculates a preceding duty command value Duty_1st and a following duty command value Duty_2nd in accordance with Table 5 in the following step S18. Then, the preceding duty command value Duty_1st is output as the duty command value (first duty command value Duty_UVW1) for the first inverter 18, and the following duty command value Duty_2nd is output as the duty command value (second duty command value Duty_UVW2) for the second inverter 19. On the other hand, when it is determined in step S24 that the second inverter 19 is the preceding inverter and the second inverter 19 is the following inverter, the above is reversed. That is, the preceding duty command value Duty_1st is output as the second duty command value Duty_UVW2, and the succeeding duty command value Duty_2nd is output as the first duty command value Duty_UVW1.

[0162] Note that step S24 is executed when the ASC control mode is the first ASC mode (ASC1), and is skipped when the ASC control mode is the second ASC mode (ASC2). In this case, the ASC switching processing unit 43 calculates the leading duty command value Duty_1st and the subsequent duty command value Duty_2nd in accordance with Table 5 in the subsequent step S18, but the leading duty command value Duty_1st and the subsequent duty command value Duty_2nd are the same value. Here, it is assumed that the leading duty command value Duty_1st is output as the first duty command value Duty_UVW1, and the subsequent duty command value Duty_2nd is output as the second duty command value UVW2.

[0163] 13 is a time chart showing an example of a PWM signal in the first ASC mode (ASC1). In FIG. 13, the PWM signal D for the U phase of the first inverter 18 is uu1 * ,D ul1 *and the PWM signal D for the U phase of the second inverter 19. uu2 * ,D ul2 * In addition, in FIG. 13, the reference ASC switching signal S STD After switching from ON to OFF, at time t0 when control period P1 switches to control period P2, the U-phase current i u is essentially at its peak, and the U-phase ASC switching signal S U Here, the U-phase current i u is assumed to be positive, so the first inverter 18 is the trailing inverter and the second inverter 19 is the leading inverter.

[0164] As shown in FIG. 13, at time t0, the U-phase ASC switching signal S U When the ASC switch control unit 43 changes from ON to OFF, the ASC switch control unit 43 calculates a leading duty command value Duty_1st and a trailing duty command value Duty_2nd in the control period P2. Here, since the first ASC mode (ASC1) is selected, Duty_1st=50[%] and Duty_2nd=50+100×(DT+T p ) / τ [%]. That is, the delay time T delay is the dead time DT and the additional time T p is set to the sum of (T delay =DT+T p ). As described above, the first inverter 18 is the subsequent inverter, and the second inverter 19 is the preceding inverter. Therefore, in the control period P3, the duty command value (Duty_U1) for the U-phase arm (Q1, Q2) of the first inverter 18 is set to 50[%], and the duty command value (Duty_U2) for the U-phase arm (Q7, Q8) of the second inverter 19 is set to 50+100×(DT+T p ) / τ[%].

[0165] As a result, first, at time t a In this case, the PWM signal D for the U-phase upper arm (Q7) of the second inverter 19 is uu2* Then, at the time t b In this case, the PWM signal D for the U-phase lower arm (Q8) of the second inverter 19 is ul2 * is switched from OFF to ON. Then, at time t b Additional time T p Time t has passed c In this case, the PWM signal D for the U-phase upper arm (Q1) of the first inverter 18 is uu1 * Then, at the time t d In this case, the PWM signal D for the U-phase lower arm (Q2) of the first inverter 18 is ul1 * switches from off to on.

[0166] Therefore, at time t a The state up to this point is the initial state for U-phase switching. a From time t d The state up to time t a From time t b The state up to time t b From time t c The state up to time t c From time t d The state up to time t d The state after this is the final state related to the U-phase switching.

[0167] As mentioned above, in FIG. 13, the PWM signal D uu1 * ,D ul1 * ,D uu2 * ,D ul2 * However, the same applies to the V-phase and W-phase. However, the ASC switching signal S U ,S V ,S W is the phase current iu ,i v ,i w Therefore, the PWM signals D of the V and W phases are switched at the timing that can be considered as peaks. vu1 * ~D wl1 * ,D vu2 * ~D wl2 * The timing of switching is U-phase PWM signal D uu1 * ,D ul1 * ,D uu2 * ,D ul2 * The timing of the switch is different.

[0168] 14 is a time chart showing an example of a PWM signal in the second ASC mode (ASC2). FIG. 14 shows an example of a PWM signal in a scene similar to that shown in FIG. 13, except that the second ASC mode is selected. That is, FIG. 14 shows the PWM signal D for the U phase of the first inverter 18 for four control periods P1 to P4. uu1 * ,D ul1 * and the PWM signal D for the U phase of the second inverter 19. uu2 * ,D ul2 * In addition, in FIG. 14, the reference ASC switching signal S STD After switching from ON to OFF, at time t0 when control period P1 switches to control period P2, the U-phase current i u is essentially at its peak, and the U-phase ASC switching signal S U changes from ON to OFF. Then, the U-phase current i u is positive, the first inverter 18 is the trailing inverter and the second inverter 19 is the leading inverter.

[0169] As shown in Fig. 14, when the U-phase ASC switching signal SU changes from ON to OFF at time t0, the ASC switching processing unit 43 calculates the leading duty command Duty_1st and the trailing duty command value Duty_2nd in the control period P2. Here, since the second ASC mode (ASC2) is selected, Duty_1st = 50 [%] and Duty_2nd = 50 [%]. That is, the delay time T related to the switching of the first inverter 18 and the second inverter 19 is delay is zero (T delay = 0). Therefore, in the control period P3, the duty command value (Duty_U1) for the U-phase arm (Q1, Q2) of the first inverter 18 is set to 50[%], and the duty command value (Duty_U2) for the U-phase arm (Q7, Q8) of the second inverter 19 is set to 50[%].

[0170] Therefore, at time t a In this case, the PWM signal D for the U-phase upper arms (Q1, Q7) of the first inverter 18 and the second inverter 19 is uu1 * ,D uu2 * is switched from ON to OFF, i.e., the delay time T delay is zero, the time t a At time t when the U-phase upper arm (Q7) of the second inverter 19 switches from on to off, c and are essentially at the same time (t a =t c As a result, after the dead time DT, the U-phase lower arm (Q2) of the first inverter 18 switches from OFF to ON at time t b At time t when the U-phase lower arm (Q8) of the second inverter 19 switches from OFF to ON, d and also at substantially the same time (t b =t d )

[0171] Therefore, in the second ASC mode, at time t a =t cFrom the previous starting state, the first inverter 18 and the second inverter 19 start switching simultaneously, and after the dead time DT has elapsed, at time t b =t d In other words, in the second ASC mode, the first inverter 18 and the second inverter 19 are switched simultaneously without forming a transition state as in the first ASC mode.

[0172] As mentioned above, in FIG. 14, the PWM signal D uu1 * ,D ul1 * ,D uu2 * ,D ul2 * However, the same applies to the V-phase and W-phase. However, the ASC switching signal S U ,S V ,S W is the phase current i u ,i v ,i w Therefore, the PWM signals D of the V and W phases are switched at the timing that can be considered as peaks. vu1 * ~D wl1 * ,D vu2 * ~D wl2 * The timing of switching is U-phase PWM signal D uu1 * ,D ul1 * ,D uu2 * ,D ul2 * The timing of the switch is different.

[0173] Figure 15 shows the phase current i in the first ASC mode (ASC1). u ,i v ,i w 15 is an explanatory diagram showing the transition of the U-phase current i u When (iu >0), the U-phase arms (Q1, Q2, Q7, Q8) of the first inverter 18 and the second inverter 19 are switched first, prior to the V-phase and W-phase. u When the V-phase current i v and W-phase current i w is negative (i v ,i w <0). In the switching of this U-phase arm, the first inverter 18 is the subsequent inverter, and the second inverter 19 is the preceding inverter.

[0174] FIG. 15(A) shows the initial state of the upper short-circuit control (initial state of the U-phase switching). As shown in FIG. 15(A), in the initial state, the U-phase current i u flows from the U-phase upper arm (Q1) of the first inverter 18 to the U-phase stator coil (U), and circulates through the freewheel diode of the U-phase upper arm (Q7) of the second inverter 19. v flows from the V-phase upper arm (Q9) of the second inverter 19 to the V-phase stator coil (V), and circulates through the freewheel diode of the V-phase upper arm (Q3) of the first inverter 18. Then, the W-phase current i W is the upper arm (Q 11 ) into the W-phase stator coil (W), and circulates through the freewheel diode of the W-phase upper arm (Q5) of the first inverter 18. At this time, the phase current i u ,i v ,i w is consumed by circulating through the first inverter 18, the rotating electrical machine 10, and the second inverter 19. In addition, the DC current i dc is zero (i dc =0). Therefore, the smoothing capacitor 39 is neither charged nor discharged.

[0175] 15(B) shows a first transition state related to the switching of the U phase. That is, FIG. 15(B) shows the first transition state related to the switching of the U phase ASC switching signal S U15(B), in the first transition state, the phase current i u ,i v ,i w Therefore, the phase current i generated by the induced voltage of the rotating electrical machine 10 u ,i v ,i w is consumed by circulating through the first inverter 18, the rotating electrical machine 10, and the second inverter 19. In addition, the DC current i dc is zero and (i dc =0), the smoothing capacitor 39 is neither charged nor discharged.

[0176] 15(C) shows a second transition state related to the switching of the U phase. That is, FIG. 15(C) shows a state in which the U-phase upper arm (Q7) of the second inverter 19, which is the preceding inverter, is switched from on to off, and then the dead time DT has elapsed and the U-phase lower arm (Q8) of the second inverter 19 is switched from off to on. As shown in FIG. 15(C), in the second transition state, the V-phase current i v and W-phase current i w There is no change in U-phase current i u Specifically, the flow of U-phase current i u flows from the smoothing capacitor 39 through the U-phase upper arm (Q1) of the first inverter 18 to the U-phase stator coil (U), and circulates through the U-phase lower arm (Q8) of the second inverter 19. Therefore, the DC current i flowing through the smoothing capacitor 39 dc becomes positive (i dc =+|i u |>0). Therefore, the V-phase current i generated by the induced voltage of the rotating electrical machine 10 v and W-phase current i w is consumed by circulating through the first inverter 18, the rotating electrical machine 10, and the second inverter 19, and the smoothing capacitor 39 u is discharged by

[0177] 15(D) shows a third transition state related to the switching of the U-phase. That is, FIG. 15(D) shows a transition state after the switching of the U-phase arm (Q7, Q8) of the second inverter 19, which is the preceding inverter, is completed and then an additional time T p 15(D), in the third transition state, the V-phase current i v and W-phase current i w There is still no change in the flow of U-phase current i u Specifically, the flow of U-phase current i u flows from the freewheel diode of the U-phase lower arm (Q2) of the first inverter 18 to the U-phase stator coil (U), and circulates through the U-phase lower arm (Q8) of the second inverter 19. Therefore, the DC current i dc becomes zero again (i dc = 0). Therefore, the phase current i generated by the induced voltage of the rotating electrical machine 10 u ,i v ,i w is consumed by circulating through the first inverter 18, the rotating electric machine 10, and the second inverter 19, and the smoothing capacitor 39 is neither charged nor discharged.

[0178] Fig. 15(E) shows the final state of the U-phase switching. That is, Fig. 15(D) shows the state in which the U-phase upper arm (Q1) of the first inverter 18, which is the subsequent inverter, is switched from on to off, and then the dead time DT has elapsed and the U-phase lower arm (Q2) of the first inverter 18 is switched from off to on. As shown in Fig. 15(E), in the final state, the phase current i u ,i v ,i w Therefore, the DC current i flowing through the smoothing capacitor 39 dc is zero and (i dc =0), the smoothing capacitor 39 is neither charged nor discharged. u ,i v ,i wis consumed by circulating through the first inverter 18, the rotating electric machine 10, and the second inverter 19.

[0179] Here, we take as an example a scene in which the U-phase arm (Q1, Q2, Q7, Q8) is switched when switching from upper-side short-circuit control to lower-side short-circuit control, but the V-phase arm (Q3, Q4, Q9, Q 10 ) and W-phase arm (Q5, Q6, Q 11 ,Q 12 ) is switched in a similar manner. The same applies to a scene where the control is switched from low-side short-circuit control to high-side short-circuit control. Therefore, in the first ASC mode, the smoothing capacitor 39 is not charged when switching between high-side short-circuit control and low-side short-circuit control, so the smoothing capacitor 39 is protected. Furthermore, the first ASC mode can discharge the smoothing capacitor 39.

[0180] Figure 16 shows the phase current i in the second ASC mode (ASC2). u ,i v ,i w 15. Here, as an example, a scene in which the control is switched from the upper short circuit control to the lower short circuit control is shown. That is, the U-phase current i u When (i u >0), the U-phase arms (Q1, Q2, Q7, Q8) of the first inverter 18 and the second inverter 19 are switched first, prior to the V-phase and W-phase. u When the V-phase current i v and W-phase current i w is negative (i v ,i w <0). In the switching of this U-phase arm, the first inverter 18 is the subsequent inverter, and the second inverter 19 is the preceding inverter.

[0181] FIG. 16(A) shows the initial state of the upper short-circuit control (initial state of the U-phase switching). As shown in FIG. 16(A), even in the second ASC mode, the phase current iu ,i v ,i w The flow of the phase current i generated by the induced voltage of the rotating electric machine 10 is the same as that in the first ASC mode (see FIG. 15(A)). u ,i v ,i w is consumed by circulating through the first inverter 18, the rotating electrical machine 10, and the second inverter 19. In addition, the DC current i dc is zero (i dc =0). Therefore, the smoothing capacitor 39 is neither charged nor discharged.

[0182] FIG. 16(B) shows the U-phase ASC switching signal S U is switched from ON to OFF, and the U-phase upper arms (Q1, Q7) of the first inverter 18 and the second inverter 19 are switched from ON to OFF. At this time, the V-phase current i v and W-phase current i w The flow of U-phase current i u Specifically, the flow of U-phase current i u flows from the freewheel diode of the U-phase lower arm (Q2) of the first inverter 18 to the U-phase stator coil (U), and then passes through the freewheel diode of the U-phase upper arm (Q7) of the second inverter 19 and flows into the smoothing capacitor 39. Therefore, the DC current idc flowing through the smoothing capacitor 39 becomes negative (i dc =-|i u |<0). Therefore, the V-phase current i generated by the induced voltage of the rotating electrical machine 10 v and W-phase current i w is consumed by circulating through the first inverter 18, the rotating electrical machine 10, and the second inverter 19, but the smoothing capacitor 39 consumes the U-phase current i u is charged by

[0183] 16(C) shows the final state of the U-phase switching. That is, FIG. 16(C) shows the state after the U-phase upper arms (Q1, Q7) of the first inverter 18 and the second inverter 19 have been switched from on to off, the dead time DT has elapsed, and the U-phase lower arms (Q2, Q8) have been switched from off to on. As shown in FIG. 16(C), in the final state, the V-phase current i v and W-phase current i w The flow of U-phase current i u Specifically, the flow of U-phase current i u flows from the freewheel diode of the U-phase lower arm (Q2) of the first inverter 18 to the U-phase stator coil (U), and circulates through the U-phase lower arm (Q8) of the second inverter 19. Therefore, the phase current i u ,i v ,i w is consumed by circulating through the first inverter 18, the rotating electrical machine 10, and the second inverter 19. In addition, the DC current i dc is zero and (i dc =0), the smoothing capacitor 39 is neither charged nor discharged.

[0184] Here, we take as an example a scene in which the U-phase arm (Q1, Q2, Q7, Q8) is switched when switching from upper-side short-circuit control to lower-side short-circuit control, but the V-phase arm (Q3, Q4, Q9, Q 10 ) and W-phase arm (Q5, Q6, Q 11 ,Q 12 ) is switched in the same way. The same thing happens when switching from the lower side short circuit control to the upper side short circuit control. Therefore, in the second ASC mode, when switching between the upper side short circuit control and the lower side short circuit control, the phase current i u ,i v ,i w Therefore, in the second ASC mode, the smoothing capacitor 39 can be charged while consuming the DC voltage V dc is low (V dc ≦V thThis is selected in a situation where it is desirable to charge the smoothing capacitor 39 in anticipation of a system restart (recharging the smoothing capacitor 39), etc.

[0185] [Variations] In the first and second embodiments, overspeed and overcurrent are mainly detected as system abnormalities, and ASC control is performed when these abnormalities are present. However, as described above, when sensors such as the current sensor 14 fail, there are times when the relay 16 must be turned off and ASC control must be performed for safety. The ASC control of the first and second embodiments can also be used when sensors fail. However, in the first and second embodiments, when generating the duty command values Duty_UVW1 and Duty_UVW2 for performing ASC control, the phase current i u ,i v ,i w Therefore, in the following, it is assumed that the phase current i can be detected normally when the current sensor 14 fails. u ,i v ,i w and estimate the estimated phase current (hereinafter referred to as the estimated phase current i u ′,i v ′,i w A modified example for performing ASC control of the first or second embodiment will be described below using the above-described reference numerals.

[0186] 17 is a block diagram showing the configuration of the first PWM control unit 33 and the second PWM control unit 34 according to the modified example. As shown in FIG. 17, the first PWM control unit 33 and the second PWM control unit 34 according to the modified example include a current selection unit 50 in addition to an up / down switching signal generation unit 41, a timing adjustment processing unit 42, and an ASC switching processing unit 43. In this modified example, the status signal S state represents the status of "normal" or "abnormal", and when the status is "abnormal", includes information indicating the location where the abnormality occurred or the content of the abnormality.

[0187] The current selection unit 50 receives the status signal S state When the status signal S is "abnormal", it is checked whether the abnormality is due to a failure of the current sensor 14. If the status signal S is abnormal due to a cause other than a failure of the current sensor 14, state indicates an "abnormality," the current selection unit 50 selects the phase current i from the current sensor 14. u ,i v ,i w and obtain the phase current i u ,i v ,i w The detected value is input to the timing adjustment processing unit 42 and the ASC switching processing unit 43.

[0188] On the other hand, the status signal S state When the cause of the "abnormal" indication includes a failure of the current sensor 14, the current selection unit 50 selects the phase current i u ,i v ,i w Specifically, the current selection unit 50 estimates the electrical angle θ and the magnet magnetic flux Φ according to the following equation (8). a , and d-axis inductance L d Based on this, the estimated phase current i u ′,i v ′,i w Then, the current selection unit 50 calculates the phase current i u ,i v ,i w Instead of the detected value of the estimated phase current i u ′,i v ′,i w The PWM control unit 24 inputs the duty command values Duty_UVW1, Duty_UVW2 for ASC control to the timing adjustment processing unit 42 and the ASC switching processing unit 43. This allows the PWM control unit 24 to generate the duty command values Duty_UVW1, Duty_UVW2 for ASC control even if the current sensor 14 fails.

[0189]

number

[0190] In addition, the magnetic flux Φa and d-axis inductance L d is a parameter specific to the rotating electrical machine 10 and is therefore a known parameter. a / L d , 0] is the dq-axis current [i d ,i q ].

[0191] As described above, the inverter control methods according to the first embodiment, the second embodiment, and the modified example are inverter control methods for controlling the first inverter 18 that connects one end of the stator coils (U, V, W) of the open-winding rotating electric machine (10) to the DC power supply (11) via the smoothing capacitor 39, and the second inverter 19 that connects the other end of the stator coils (U, V, W) to the DC power supply (11) via the smoothing capacitor 39. In this inverter control method, the upper arms (Q1, Q3, Q5, Q7, Q9, Q 11 ) is turned on, and the lower arms (Q2, Q4, Q6, Q8, Q 10 ,Q 12 ) and the upper arms (Q1, Q3, Q5, Q7, Q9, Q 11 ) is turned off, and the lower arms (Q2, Q4, Q6, Q8, Q 10 ,Q 12 ) is alternately executed. When switching between the upper side short circuit control and the lower side short circuit control, the phase current i u ,i v ,i w and obtain the phase current i u ,i v ,i w Based on this, the first inverter 18 and the second inverter 19 are switched at different timings for each phase.

[0192] In this way, when switching between the upper side short circuit control and the lower side short circuit control in the open winding type rotating electric machine 10, the phase current i u ,i v ,i w Based on this, the first inverter 18 and the second inverter 19 are switched at different timings for each phase of the rotating electrical machine 10, thereby generating a phase current i u ,i v ,i w This allows switching between the upper-side short-circuit control and the lower-side short-circuit control without charging the smoothing capacitor 39. In other words, it is possible to switch between the upper-side short-circuit control and the lower-side short-circuit control while protecting the smoothing capacitor 39.

[0193] In addition, in the inverter control methods according to the first embodiment, the second embodiment, and the modified example, the reference timing (S STD ) and set the phase current i u ,i v ,i w Based on the reference timing (S STD ), by delaying the timing at which the first inverter 18 and the second inverter 19 are actually switched on (S U ,S V ,S W ), the first inverter 18 and the second inverter 19 are switched on and off at different timings for each phase.

[0194] In this way, the reference timing (S STD ) to the phase current i u ,i v ,i w By delaying the phase current i based on u ,i v ,i w This allows the first inverter 18 and the second inverter 19 to be switched at an appropriate timing so that the smoothing capacitor 39 is not charged. In other words, it is particularly easy to protect the smoothing capacitor 39 when switching between the upper side short-circuit control and the lower side short-circuit control.

[0195] In the inverter control method according to the first embodiment and the modified example, in particular, the phase current i u ,i v ,i w When the magnitude of the voltage Vcc becomes zero, the first inverter 18 and the second inverter 19 are switched on and off.

[0196] Thus, the phase current i u ,i v ,i w If the first inverter 18 and the second inverter 19 are switched at the timing when the magnitude of the current is substantially zero, no current flows into the smoothing capacitor 39. Therefore, it is particularly easy to protect the smoothing capacitor 39 when switching between the upper side short-circuit control and the lower side short-circuit control.

[0197] In the inverter control method according to the first embodiment and the modified example, in particular, the phase current i u ,i v ,i w At the timing when the magnitude of the signal becomes zero, the upper arms of the first inverter 18 and the second inverter 19 are switched on simultaneously, and the lower arms of the first inverter 18 and the second inverter 19 are switched on simultaneously.

[0198] Thus, the phase current i u ,i v ,i w When the first inverter 18 and the second inverter 19 are switched at the timing when the magnitude of the phase current i becomes zero, it is preferable to switch the first inverter 18 and the second inverter 19 simultaneously. u ,i v ,i w Since the switching is performed quickly while the magnitude of the current is substantially zero, it is easy to protect the smoothing capacitor 39 particularly when switching between the upper side short-circuit control and the lower side short-circuit control.

[0199] In the inverter control method according to the second embodiment and the modification, the phase current i u ,i v ,i wThe magnitude of the predetermined current threshold i th At this timing, the first inverter 18 and the second inverter 19 are switched on and off.

[0200] Thus, the phase current i u ,i v ,i w is the current threshold i th Even when the first inverter 18 and the second inverter 19 are switched at timings having the above significant values, if the switching is performed at different timings for each phase, the phase current i u ,i v ,i w This allows switching between the upper-side short-circuit control and the lower-side short-circuit control without charging the smoothing capacitor 39. In other words, it is possible to switch between the upper-side short-circuit control and the lower-side short-circuit control while protecting the smoothing capacitor 39.

[0201] In the inverter control method according to the second embodiment and the modified example, in particular, the phase current i u ,i v ,i w The magnitude of the current threshold i th In the phases where the phase current i u ,i v ,i w The magnitude of the current threshold i th With respect to the initial state before the above, a transition state is formed in which the state of either one of the first inverter 18 and the second inverter 19 (the subsequent inverter) is maintained in the same state as the initial state, and the switching of either the first inverter 18 or the second inverter 19 (the preceding inverter) is started in advance, and a predetermined time (T delay ) has elapsed, by starting switching of one of the inverters (the subsequent inverter), the states of the arms of the first inverter 18 and the second inverter 19 are formed into a final state that is the opposite of the initial state.

[0202] Thus, the phase current i u ,i v,i w The magnitude of the current threshold i th When the first inverter 18 and the second inverter 19 are switched at the above timing, the switching timing of the first inverter 18 and the second inverter 19 is shifted to provide a transition state, thereby discharging the smoothing capacitor 39. Therefore, it is particularly easy to protect the smoothing capacitor 39 when switching between the upper side short-circuit control and the lower side short-circuit control.

[0203] In the inverter control method according to the second embodiment and the modified example, in particular, delay =DT+T p ) is longer than the dead time DT required to alternate between on and off of the paired upper and lower arms.

[0204] Specifically, in this way, the predetermined time (T delay ) is set to be longer than the dead time DT, the portion longer than the dead time DT (additional time T p ) is formed, the smoothing capacitor 39 is discharged. Therefore, when switching between the upper side short-circuit control and the lower side short-circuit control, the smoothing capacitor 39 is easily protected.

[0205] In the inverter control method according to the second embodiment and the modification, the phase current i u ,i v ,i w Depending on the direction of the arrows, it is determined which of the first inverter 18 and the second inverter 19 will start switching first.

[0206] Thus, the phase current i u ,i v ,i w Based on the direction of the inverters 18 and 19, it is possible to appropriately determine which of the first inverter 18 and the second inverter 19 is the preceding inverter and which is the succeeding inverter. Therefore, it is particularly easy to protect the smoothing capacitor 39 when switching between the upper side short-circuit control and the lower side short-circuit control.

[0207] In the inverter control method according to the second embodiment and the modification, the phase current i u ,i v ,i w The magnitude of the predetermined current threshold i th In the phases where the above conditions are met, the first inverter 18 or the second inverter 19 is switched on first (the preceding inverter) and then the predetermined time (T delay ) has elapsed, the first mode (ASC1) starts switching the other inverter (subsequent inverter) of the first inverter 18 or the second inverter 19, and the phase current i u ,i v ,i w The magnitude of the current threshold i th In the phases described above, there is a second mode (ASC2) in which the first inverter 18 and the second inverter 19 are simultaneously switched. dc ) based on which the first mode (ASC1) and the second mode (ASC2) are switched.

[0208] In this way, when switching between upper-side short-circuit control and lower-side short-circuit control, by using both the first ASC mode (ASC1) that discharges the smoothing capacitor 39 and the second ASC mode (ASC2) that charges the smoothing capacitor 39, it is possible to appropriately maintain the power (energy) of the smoothing capacitor 39 even in situations where ASC control must be performed. This allows the system to be restarted smoothly (recharge the smoothing capacitor 39).

[0209] In the inverter control methods according to the first embodiment, the second embodiment, and the modified examples (especially the modified examples), the phase current i u ,i v ,i w When the current sensor 14 for detecting the phase current i fails, the phase current i is detected based on the electrical angle θ of the open-winding type rotating electric machine (10). u ,i v ,i w and the estimated phase current (i u ′,i v ′,iw Based on the above, duty command values (Duty_UVW1, Duty_UVW2) for controlling the first inverter 18 and the second inverter 19 are calculated.

[0210] In this way, the estimated phase current i u ′,i v ′,i w By using the ', it is possible to perform ASC control in an appropriate mode even if the current sensor 14 fails. Therefore, it is possible to protect the smoothing capacitor 39 particularly reliably when switching between the upper side short-circuit control and the lower side short-circuit control.

[0211] The inverter control device according to the first embodiment, the second embodiment, and the modified example is an inverter control device (controller 13) that controls a first inverter 18 that connects one end of a stator coil (U, V, W) of an open-winding rotating electric machine (10) to a DC power supply (11) via a smoothing capacitor 39, and a second inverter 19 that connects the other end of the stator coil (U, V, W) to the DC power supply (11) via the smoothing capacitor 39. The inverter control device (controller 13) controls the upper arms (Q1, Q3, Q5, Q7, Q9, Q 11 ) is turned on, and the lower arms (Q2, Q4, Q6, Q8, Q 10 ,Q 12 ) and the upper arms (Q1, Q3, Q5, Q7, Q9, Q 11 ) is turned off, and the lower arms (Q2, Q4, Q6, Q8, Q 10 ,Q 12 ) is turned on. When switching between the upper side short circuit control and the lower side short circuit control, the PWM control unit 24 controls the phase current i u ,i v ,i w and obtain the phase current i u ,i v ,iw Based on this, the first inverter 18 and the second inverter 19 are switched at different timings for each phase.

[0212] In this way, when switching between the upper side short circuit control and the lower side short circuit control in the open winding type rotating electric machine 10, the phase current i u ,i v ,i w Based on this, the first inverter 18 and the second inverter 19 are switched at different timings for each phase of the rotating electrical machine 10, thereby generating a phase current i u ,i v ,i w This allows switching between the upper-side short-circuit control and the lower-side short-circuit control without charging the smoothing capacitor 39. In other words, it is possible to switch between the upper-side short-circuit control and the lower-side short-circuit control while protecting the smoothing capacitor 39.

[0213] Although the embodiments and modifications of the present invention have been described above, the configurations described in the above embodiments and modifications merely illustrate some of the application examples of the present invention and are not intended to limit the technical scope of the present invention. For example, the present invention can be suitably implemented even when the rotating electric machine 10 has multiple phases other than three (for example, five or more phases). [Explanation of symbols]

[0214] 10: Rotating electric machine, 11: Battery, 12: Inverter, 13: Controller, 14: Current sensor, 15: Rotation sensor, 16: Relay, 17: Voltage sensor, 18: First inverter, 19: Second inverter, 21: Torque control unit, 22: Voltage distribution unit, 23: Coordinate conversion unit, 24: PWM control unit, 25: PWM signal generator, 26: Coordinate conversion unit, 27: Rotation speed calculation unit, 28: Abnormality detection unit, 31: First conversion unit, 32: Second conversion unit, 33: First PWM control unit, 34: Second PWM control unit, 35: Output determination unit, 36: First PWM signal generator, 37: Second PWM signal generator, 39: Smoothing capacitor, 41: Up / down switching signal generation unit, 42: Timing adjustment processing unit, 43: ASC switching processing unit, 50: Current selection unit, 100: Electric vehicle

Claims

1. A method for controlling an inverter, the method comprising: controlling a first inverter that connects one end of a stator coil of an open-winding rotating electric machine to a DC power supply via a smoothing capacitor; and controlling a second inverter that connects the other end of the stator coil to the DC power supply via the smoothing capacitor, the method comprising: alternately executing an upper-side short-circuit control for turning on upper arms of the first inverter and the second inverter and turning off lower arms of the first inverter and the second inverter, and a lower-side short-circuit control for turning off upper arms of the first inverter and the second inverter and turning on lower arms of the first inverter and the second inverter; When switching between the upper-side short-circuit control and the lower-side short-circuit control, phase currents that flow through each phase of the open-winding rotating electric machine are acquired; switching the first inverter and the second inverter at different timings for each phase based on the phase current; Inverter control method.

2. 2. The inverter control method according to claim 1, setting a reference timing for switching between the upper-side short-circuit control and the lower-side short-circuit control; delaying timings at which the first inverter and the second inverter are actually switched with respect to the reference timing based on the phase currents, thereby switching the first inverter and the second inverter at different timings for each phase; Inverter control method.

3. 3. The inverter control method according to claim 1, further comprising: switching the first inverter and the second inverter at a timing when the magnitude of the phase current becomes zero; Inverter control method.

4. 4. The inverter control method according to claim 3, At a timing when the magnitude of the phase current becomes zero, the upper arms of the first inverter and the second inverter are simultaneously switched on, and the lower arms of the first inverter and the second inverter are simultaneously switched on. Inverter control method.

5. 3. The inverter control method according to claim 1, further comprising: switching on and off the first inverter and the second inverter at a timing when the magnitude of the phase current becomes equal to or greater than a predetermined current threshold; Inverter control method.

6. 6. The inverter control method according to claim 5, In the phase where the magnitude of the phase current is equal to or greater than the current threshold, forming a transition state in which, with respect to an initial state before the magnitude of the phase current becomes equal to or greater than the current threshold, a state of one of the first inverter and the second inverter is maintained the same as the initial state, while switching of the other of the first inverter and the second inverter is started in advance; By starting the switching of one of the inverters after a predetermined time has elapsed since the switching of the other inverter has started in advance, a final state is formed in which the states of the arms of the first inverter and the second inverter are reversed to the initial state. Inverter control method.

7. 7. The inverter control method according to claim 6, the predetermined time is longer than the dead time required when switching on and off the paired upper arm and lower arm, Inverter control method.

8. 7. The inverter control method according to claim 6, determining which of the first inverter and the second inverter should start switching first, depending on the direction of the phase current; Inverter control method.

9. 6. The inverter control method according to claim 5, a first mode in which, in the phase in which the magnitude of the phase current is equal to or greater than the current threshold, switching of one of the first inverter and the second inverter is started first, and then, after a predetermined time has elapsed, switching of the other of the first inverter and the second inverter is started; a second mode in which the first inverter and the second inverter are simultaneously switched in the phase when the magnitude of the phase current is equal to or greater than the current threshold; and switching between the first mode and the second mode based on the voltage of the smoothing capacitor; Inverter control method.

10. 3. The inverter control method according to claim 1, further comprising: When a current sensor for detecting the phase current fails, the phase current is estimated based on an electrical angle of the open-winding type rotating electric machine; calculating a duty command value for controlling the first inverter and the second inverter based on the estimated phase current; Inverter control method.

11. 1. An inverter control device that controls a first inverter that connects one end of a stator coil of an open-winding rotating electric machine to a DC power supply via a smoothing capacitor, and a second inverter that connects the other end of the stator coil to the DC power supply via the smoothing capacitor, a PWM control unit that alternately executes upper-side short-circuit control that turns on upper arms of the first inverter and the second inverter and turns off lower arms of the first inverter and the second inverter, and lower-side short-circuit control that turns off upper arms of the first inverter and the second inverter and turns on lower arms of the first inverter and the second inverter, When switching between the upper side short circuit control and the lower side short circuit control, the PWM control unit: phase currents that flow through each phase of the open-winding rotating electric machine are acquired; switching the first inverter and the second inverter at different timings for each of the phases based on the phase current; Inverter control device.

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