JP2015095978A - Vehicular electromagnetic noise control apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control apparatus capable of generating an electromagnetic noise more effectively without deteriorating controllability of a rotary electric machine during a low-speed travel.SOLUTION: A control apparatus includes a DC/DC converter 14, an inverter, and a motor-generator MG 2. A control part 18 performs: controlling the DC/DC converter 14 so that a high-voltage-side voltage is raised to a system upper limit voltage, if a vehicular speed is in a low-speed zone of a given threshold or less and in a first low-speed zone that is relatively low-speed, and controlling the inverter 16 in a PWM control mode; and controlling the DC/DC converter 14 so that the high-voltage-side voltage is raised to a voltage enabling an over-modulation control mode and controlling the inverter 16 in the over-modulation control mode, if the vehicle speed is in a second low-speed zone that is relatively higher speed than the first low-speed zone.

Description

  The present invention relates to a vehicle electromagnetic sound control device, and more particularly to a technique for outputting an approaching sound to a pedestrian outside the vehicle.

  Conventionally, in electric vehicles such as a hybrid vehicle (HV) and an electric vehicle (EV), a technique for generating electromagnetic noise as an approaching sound from a rotating electric machine and an inverter has been proposed.

  In Patent Document 1 below, when the vehicle speed V is less than the threshold value Vref during electric driving, the target voltage VH on the high voltage side of the boost converter is higher than when the vehicle speed V is equal to or higher than the threshold value Vref. In addition, by setting the target voltage VH on the high voltage side of the boost converter to be higher as the vehicle speed V is larger, there is a technology for notifying a pedestrian or the like of the approach of the vehicle using an approach sound corresponding to the vehicle speed V. It is disclosed.

  Patent Document 2 discloses that the volume and pitch of electromagnetic sound generated from an electric motor can be controlled by changing the carrier frequency of the inverter.

JP 2013-90553 A JP 2013-143904 A

  It is possible to increase the electromagnetic noise by increasing the target voltage VH on the high voltage side of the boost converter when the vehicle speed V is lower than the threshold value Vref, and further reduce the electromagnetic frequency by lowering the carrier frequency of the inverter. However, if the carrier frequency of the inverter is lowered, the control cycle of the inverter becomes longer and the ripple component contained in the current flowing in the phase coil of the rotating electrical machine becomes larger. The range that can be controlled is limited.

  An object of the present invention is to provide a control device that can generate electromagnetic noise more effectively without reducing the controllability of a rotating electrical machine during low-speed traveling.

The present invention relates to an electromagnetic sound control device for a vehicle comprising a DC / DC converter, an inverter connected to the DC / DC converter, and a rotating electrical machine connected to the inverter, wherein the vehicle speed is lower than a predetermined threshold value. The DC / DC converter is controlled so that the high-voltage side voltage of the DC / DC converter is boosted to the system upper limit voltage in the first low-speed range that is a relatively low speed, and the PWM control mode And when the vehicle speed is a second low speed range relatively higher than the first low speed range, the high voltage side voltage of the DC / DC converter reaches a voltage capable of overmodulation control mode. A control unit that controls the DC / DC converter so as to boost the voltage and controls the inverter in an overmodulation control mode is provided.

  In the present invention, the current ripple component is increased by boosting the high-voltage side voltage of the DC / DC converter to the system upper limit and performing PWM control of the inverter when the first low-speed range is a relatively low-speed range. The electromagnetic noise can be increased, and the electromagnetic noise can be further increased by appropriately reducing the carrier frequency of the PWM control. However, there is an upper limit to the number of rotations at which a low carrier frequency can be set in PWM control, and the controllability of the rotating electrical machine is reduced when the vehicle speed is increased. Therefore, even in the same low speed range, in the second low speed range, which is relatively faster than the first low speed range, the inverter is controlled not in the PWM control mode but in the overmodulation control mode, thereby improving the controllability of the rotating electrical machine. Without lowering, the electromagnetic noise can be increased by utilizing the increase of the ripple component of the current due to overmodulation.

  According to the present invention, electromagnetic noise can be generated without lowering the controllability of the rotating electrical machine during low-speed traveling. Thereby, an approaching sound can be effectively generated for a pedestrian or the like outside the vehicle.

It is a system configuration figure of an embodiment. It is a control flowchart of an embodiment. It is a control flowchart of other embodiments.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a vehicle control system equipped with an electromagnetic sound control apparatus according to this embodiment. The control system 10 is mounted on a hybrid vehicle that uses one or both of an engine (not shown) and a motor generator MG2 that is a rotating electrical machine mainly used as a traveling motor as a main drive source.

  Control system 10 includes motor generator MG 2, battery 12, DC / DC converter 14 connected to battery 12, smoothing capacitors C 1 and C 2 connected to DC / DC converter 14, and boosting of DC / DC converter 14. The inverter 16 connected between the motor generator MG2 and the control unit 18 is provided.

  Motor generator MG2 is a U-phase, V-phase, and W-phase three-phase rotating electric machine that functions as a motor when electric power is supplied from battery 12 and functions as a generator during braking of the vehicle. The generated electric power is supplied to the battery 12 via the inverter 16.

  The DC / DC converter 14 includes a reactor 20 and two switching elements Sa connected in series with each other. One end of the reactor 20 is connected between the two switching elements Sa, and the other end of the reactor 20 is connected to the positive electrode side of the battery 12 via the system relay SR and the fuse F. System relay SR includes a first relay R1 and a second relay R2. The second relay R2 is connected in parallel to the first relay R1, and a resistor RW is connected in series. The control unit 18 enables the battery 12 and the DC / DC converter 14 to be electrically connected by controlling one of the first relay R1 and the second relay R2 to be turned on and the other to be turned off.

  A diode Da is connected in antiparallel to each switching element Sa of the DC / DC converter 14, and a negative electrode side of the battery 12 is connected to one switching element Sa of the two switching elements Sa. A smoothing capacitor C <b> 1 is connected between the other end of the reactor 20 and the negative electrode side of the battery 12. A second smoothing capacitor C2 is connected between both ends of the two switching elements Sa and between the inverter 16.

  In the DC / DC converter 14, the switching of the switching element Sa is controlled by the control unit 18, and the high voltage side voltage VH obtained by boosting the low voltage side voltage VL that is the output side voltage of the battery 12 is supplied to the inverter 16. The low voltage side voltage VL and the high voltage side voltage VH of the DC / DC converter 14 are detected by the low voltage sensor 22 and the high voltage sensor 24, respectively.

  The inverter 16 includes three arms Au, Av, Aw corresponding to the U-phase, V-phase, and W-phase connected in parallel to each other, and each phase arm includes two switching elements Sw connected in series with each other. A diode Di is connected to each switching element Sw in antiparallel. Each switching element Sw is switching-controlled by the control unit 18, converts a DC voltage supplied from the high voltage side of the DC / DC converter 14 into a three-phase AC voltage, and outputs it to the motor generator MG 2. During braking of the vehicle, the three-phase AC voltage output from the motor generator MG2 to the inverter 16 is converted into a DC voltage, which is stepped down by the DC / DC converter 14 and supplied to the battery 12.

  The current flowing through the power line that connects the stator coils 26u, 26v, 26w of each phase of motor generator MG2 and inverter 16 is detected by current sensor 28.

  The control unit 18 includes a single or a plurality of in-vehicle computers, and includes a PWM control unit, an overmodulation control unit, a rectangular wave control unit, and a modulation degree switching unit as functional blocks. The PWM control unit controls motor generator MG2 in the PWM control mode. The overmodulation control unit controls motor generator MG2 in the overmodulation control mode. The rectangular wave control unit controls motor generator MG2 in the rectangular wave control mode. The modulation degree switching unit switches the PWM control mode, the overmodulation control mode, and the rectangular wave control mode according to the modulation degree as basic control. The modulation degree is an effective value of a line voltage that is a necessary applied voltage of motor generator MG2 determined from a torque command value or the like with respect to high-voltage side voltage VH of DC / DC converter 14 that is a system voltage and an input voltage of inverter 16. The ratio of J (J / VH). When the modulation degree is 0.61 or less which is a preset first ratio, the inverter 16 is controlled in the PWM control mode, and when the modulation degree exceeds 0.61 and is less than 0.78 which is a preset second ratio. The inverter 16 is controlled in the overmodulation control mode, and when the degree of modulation is 0.78 or more, the inverter 16 is controlled in the rectangular wave control mode.

  The overmodulation control mode and the rectangular wave control mode are used in addition to the PWM control mode. The sine wave PWM control has a maximum modulation degree of 0.61. In order to obtain a modulation degree higher than that, the amplitude of the PWM carrier is used. This is because over-modulation control using a voltage command having a larger amplitude and rectangular wave control using a motor voltage command as a rectangular wave are required. Conventionally, since there is no problem in the PWM control mode from the low speed to the medium speed range, the PWM control mode is adopted, the mode is switched to the overmodulation control mode to improve the output in the medium speed range, and the output is improved in the high speed range. Therefore, it is switched to the rectangular wave control mode.

  As described above, the control unit 18 controls the inverter 16 in the PWM control mode in the low speed range. At this time, the control unit 18 increases the electromagnetic noise in order to generate an approaching sound to a pedestrian or the like outside the vehicle. Therefore, in the PWM control mode, the high voltage side voltage VH of the DC / DC converter 14 is increased to increase the ripple component included in the current flowing in the phase coil of the motor generator MG2, thereby increasing the electromagnetic noise. Also, the ripple component can be increased by setting the carrier frequency low. However, there is an upper limit to the number of revolutions that can be set to a low carrier frequency. For example, when the carrier frequency is 0.75 kHz and the control frequency is 6 times in one signal cycle, the 4-pole motor generator can control only up to 1875 rpm. Disappear. In other words, the rotational speed at which the carrier frequency can be set low in the PWM control mode and the electromagnetic noise can be increased without degrading the controllability of motor generator MG2, that is, the low speed range is limited.

  Therefore, the control unit 18 in the present embodiment further divides the low speed region into two first and second speed regions in order to generate electromagnetic noise in the low speed region without reducing the controllability of the motor generator MG2. The inverter 16 is controlled in the PWM control mode in which the carrier frequency is lowered in the relatively low first low speed range and the high-voltage side voltage VH is boosted to the system upper limit voltage, and in the relatively low second low speed range, the PWM is controlled. Switch to overmodulation control mode instead of control to increase electromagnetic noise. For example, when the vehicle speed is less than 10 km / h in the low speed range, the first low vehicle speed range can be set to less than 5 km / h, and the second low vehicle speed range can be set to 5 km / h or more and less than 10 km / h.

  In the present embodiment, electromagnetic noise is generated by a current ripple component generated by the voltage boosted to the system upper limit voltage and the carrier frequency in the first low speed range, and excessive in the second low speed range where the controllability of the motor generator MG2 is reduced at the low carrier frequency. It can be said that electromagnetic noise is generated by the current ripple component due to the modulation. Since the control is performed in the overmodulation control mode in the second low speed range, a decrease in controllability of the rotating electrical machine due to a low carrier frequency can be avoided, and electromagnetic sound generation and rotating electrical machine controllability can be compatible.

  FIG. 2 shows a processing flowchart in the present embodiment.

  First, the control unit 18 determines whether or not the vehicle speed is in a low speed range (S101). This determination is performed by determining whether or not the vehicle speed is less than a predetermined threshold, and the threshold is set to 10 km / h, for example.

  When it is determined that the vehicle speed is less than 10 km / h and the vehicle is in the low speed range, the control unit 18 next determines whether the vehicle speed is the first low speed range or the second low speed range (S102). This determination is performed by determining whether or not the vehicle speed is less than a predetermined threshold, and the threshold is set to 5 km / h, for example.

  When the vehicle speed is less than 5 km / h, it is determined as the first low speed range, and the control unit 18 controls the switching element Sa of the DC / DC converter 14 to increase the high-voltage side voltage VH to the system upper limit voltage, and the carrier frequency Is reduced from 5 kHz to 0.75 kHz, for example, and the inverter 16 is controlled in the PWM control mode (S103).

  Further, even if the vehicle speed is less than 10 km / h, if it is 5 km / h or more, it is determined as the second low speed range, and the control unit 18 controls the switching element Sa of the DC / DC converter 14 to set the high voltage side voltage VH. While boosting (boosting up to such an extent that it can be driven in the overmodulation control mode), the inverter 16 is controlled by switching the control mode to the overmodulation control mode (S104).

  On the other hand, when the vehicle speed is not in the low vehicle speed range, the control unit 18 performs normal control without performing the control of S102 to S104. In the normal control, the PWM control mode / overmodulation control mode / rectangular wave control mode is switched according to the state of the operating point of the motor generator MG2 given by the rotational speed and torque. That is, as the speed and torque are gradually increased, the control mode is switched from the sine wave PWM control mode to the overmodulation control mode and from the overmodulation control mode to the rectangular wave control mode.

  It should be noted that in the present embodiment, the inverter 16 is not controlled only in the PWM control mode in the low speed range, but is shifted to the overmodulation control mode in order to generate electromagnetic sound in the low speed range.

  As described above, in the present embodiment, in the low speed region, electromagnetic noise is generated by using the PWM control mode in which the high-voltage side voltage VH is increased to the system upper limit voltage and the carrier frequency is decreased, and the overmodulation control mode. However, depending on the situation, the generation of electromagnetic noise in such a low speed range may be unnecessary. For example, when there are few pedestrians or the like and the vehicle is traveling at a low speed in the vicinity of a home where the surrounding situation is well known.

  Therefore, in the case of traveling in a preset position, facility, area or the like in conjunction with an in-vehicle navigation system or the like, it is also preferable that the control shown in FIG. 2 is not executed.

  FIG. 3 shows a control flowchart in this case.

  First, the control unit 18 determines whether or not the vehicle is located within a predetermined area in conjunction with an in-vehicle navigation system or the like (S201). The navigation system transmits a detection signal to the control unit 18 when detecting that the navigation system is located within the predetermined area, and the control unit 18 determines whether or not the vehicle is within the predetermined area based on the detection signal. Data of the predetermined area is registered in advance in the memory of the navigation system. The predetermined area is, for example, near the home.

  When the vehicle is not within the predetermined area, the control unit 18 executes the control shown in FIG. 2, that is, the electromagnetic sound generation control (S202). When the vehicle is in the predetermined area, the control unit 18 prohibits electromagnetic sound generation control and does not execute it (S203). Thereby, it is possible to prevent a situation in which an approaching sound is unnecessarily generated even in an area where it is not necessary to generate an approaching sound. Here, the non-execution of S203 specifically means that the inverter 16 is controlled in the PWM control mode without increasing the high-voltage side voltage VH to the system upper limit and without decreasing the carrier frequency.

  In FIG. 3, the generation of electromagnetic sound is prohibited in the predetermined area, but conversely, the process may be to generate electromagnetic sound in the predetermined area. In this case, it is preferable to register, as the predetermined area, an intersection or a branch road with many pedestrians, a kindergarten or school neighborhood, an area with poor visibility, and the like.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to this, A various change is possible.

  For example, in the present embodiment, 10 km / h is used as a threshold value for determining the low speed range, and 5 km / h is set as a threshold value for determining whether the first low speed range or the second low speed range is used. Speed can be used. Moreover, these threshold values do not necessarily have to be fixed, and may be changed adaptively depending on the travel area. For example, in FIG. 3, the generation of electromagnetic noise is prohibited when the vehicle travels within a predetermined area, but a threshold for determining whether the vehicle is in a low speed region when traveling within the predetermined area. Is reduced downward from 10 km / h to 5 km / h, the range of the vehicle speed V determined to be the low speed range is narrowed accordingly, so that the vehicle speed range where the electromagnetic noise generation process is prohibited is expanded. On the contrary, this means that the vehicle speed range in which the electromagnetic sound generation processing is executed is expanded by changing the threshold value for determining whether or not the vehicle is in the low speed range upward from 10 km / h. is there.

10 control system, 12 battery, 14 DC / DC converter, 16 inverter, 18 control unit.

Claims (1)

A DC / DC converter;
An inverter connected to the DC / DC converter;
A rotating electrical machine connected to the inverter;
An electromagnetic sound control device for a vehicle comprising:
When the vehicle speed is a low speed range lower than a predetermined threshold and the first low speed range is a relatively low speed, the DC / DC is set so that the high-voltage side voltage of the DC / DC converter is boosted to the system upper limit voltage. When the inverter is controlled in the PWM control mode while the converter is controlled, and the vehicle speed is a second low speed range relatively higher than the first low speed range, the high voltage side voltage of the DC / DC converter is An electromagnetic noise control apparatus for a vehicle, comprising: a control unit that controls the DC / DC converter so as to boost the voltage to a voltage capable of overmodulation control mode and controls the inverter in the overmodulation control mode.

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