JP2018082542A - Electric vehicle - Google Patents

Abstract

Disclosed is a technique for accurately distinguishing between cases where noise countermeasures should be prioritized over loss and cases where loss countermeasures should be prioritized over noise in an electric vehicle equipped with an inverter. An electric vehicle includes an inverter, a control device that supplies a PWM signal for controlling the inverter to the inverter, and a signal supply device that supplies a window state signal indicating an open / closed state of a window of the vehicle body to the control device. When the vehicle speed is lower than the predetermined speed and the condition that the window state signal indicates the open state is satisfied (YES in S12), the frequency of the PWM signal is set to the frequency F1 outside the audible frequency band, while the above condition is satisfied. If not established (NO in S10 or NO in S12), the frequency F0 is lower than the frequency F1 and within the audible frequency band. [Selection] Figure 2

Description

  The technology disclosed in this specification relates to an electric vehicle. In addition, the electric vehicle includes a hybrid vehicle including a traveling motor together with an engine, and an electric vehicle and a fuel cell vehicle including only a traveling motor.

  Patent Document 1 discloses an electric vehicle including an inverter and a control device that supplies a PWM (abbreviation of pulse width modulation) signal for controlling the inverter to the inverter.

The PWM signal has a fundamental frequency and indicates an on / off time ratio for each period. The frequency of the PWM signal affects the loss due to the inverter. If the frequency is high, the loss due to the inverter increases.
The inverter emits operating noise. The frequency of the operating sound depends on the frequency of the PWM signal.
At present, if the frequency of the PWM signal is set low in order to keep the loss due to the inverter low, the operation sound of the inverter falls within the human audible frequency band, and the occupant can hear the operation sound. If the frequency of the PWM signal is set high, the operation sound of the inverter is outside the audible frequency band and the occupant cannot hear the operation sound, but the loss due to the inverter increases.

  In Patent Document 1, a high frequency is used when the rotational speed of the traveling motor does not exceed the predetermined rotational speed (operating sound is not heard but loss increases), and the rotational speed of the traveling motor exceeds the predetermined rotational speed. A technique that sometimes uses a low frequency (low operating loss can be heard though the loss is low) is disclosed. A technology is disclosed that emphasizes noise countermeasures over loss during low-speed rotation, and emphasizes loss countermeasures over noise during high-speed rotation.

JP 2010-93982 A

In the above technique, the frequency is switched only from the motor rotation speed. However, the period in which noise countermeasures should be prioritized over loss and the period in which loss countermeasures should be prioritized over noise cannot be determined from the motor speed alone. For example, even if it is a low-speed rotation period, if the window is closed, the noise is not worrisome. Even though the loss countermeasure should be emphasized, the noise countermeasure is emphasized and a wasteful loss is caused. In the case of a hybrid vehicle, although the motor speed is low, the vehicle may be traveling at a high speed, and during high speed traveling, the level of noise other than the operating noise of the inverter is high. Despite emphasis on countermeasures, wasteful loss is incurred with emphasis on noise countermeasures. In the conventional technology, it is inappropriate to distinguish between a case where noise countermeasures should be emphasized over loss and a case where loss countermeasures should be emphasized over noise.
In the present specification, a technique for accurately separating a case where noise countermeasures should be more important than loss and a case where loss countermeasures should be more important than noise is disclosed.

  An electric vehicle disclosed in this specification includes an on-board inverter, a control device that supplies a PWM signal for controlling the inverter to the inverter, and a signal supply device that supplies a window state signal indicating an open / closed state of a window of the vehicle body to the control device. Is provided. The control device sets the frequency of the PWM signal to the first frequency outside the audible frequency band when the vehicle speed is slower than the predetermined speed and the condition that the window state signal indicates the open state is satisfied. On the other hand, if the above condition is not satisfied, the second frequency is lower than the first frequency and within the audible frequency band.

If the vehicle speed is slower than a predetermined speed and the window is open, the operation sound of the inverter may be heard by the passenger and become noise. In this case, noise countermeasures should be more important than loss. According to the above configuration, in this case, the frequency of the PWM signal is the first frequency outside the audible frequency band. The operating sound is outside the audible frequency band and noise countermeasures are taken.
If the vehicle speed is higher than the predetermined speed, the operation noise of the inverter does not become noise because other noise levels are high. Or, if the window is closed, the occupant cannot hear the operation sound of the inverter. This is the case when noise countermeasures are not required. In these cases, measures against loss should be taken rather than noise. According to the above configuration, in these cases, the loss is reduced by lowering the frequency of the PWM signal. According to the above configuration, it is possible to accurately distinguish between cases where noise countermeasures should be emphasized over losses and cases where loss countermeasures should be prioritized over noise.
Details and further improvements of the technology disclosed in this specification will be described in the following “DETAILED DESCRIPTION”.

It is a figure which shows the electric vehicle of 1st, 2 Example. It is a figure which shows the frequency determination processing procedure of 1st Example. It is a figure which shows the frequency determination processing procedure of 2nd Example.

(First embodiment)
An electric vehicle 100 according to an embodiment will be described with reference to the drawings. FIG. 1 is a schematic side view of an electric vehicle. In FIG. 1, the vehicle body 101 of the electric vehicle 100 is drawn with virtual lines, and the components and devices mounted in the vehicle body 101 are drawn with solid lines. The electric vehicle 100 includes a vehicle body 101, a traveling motor 10, an inverter 12, a control device 13, a signal supply device 14, a driver seat 15a, and a rear seat 15b. The electric vehicle 100 is an electric vehicle / fuel cell vehicle that runs only with the power of a motor.

  The vehicle body 101 includes a driver seat window 102a located on the driver seat 15a side, a rear window 102b located on the rear seat 15b side, and a front compartment 103. The driver's seat window 102a and the rear window 102b open and close up and down. The front compartment 103 is located in front of the driver's seat 15a and accommodates the motor 10, the inverter 12, and the control device 13.

  The inverter 12 converts DC power from a vehicle-mounted battery (not shown) into AC power suitable for driving the motor 10 and supplies the AC power to the motor 10. The electric vehicle 100 is driven by the power of the motor 10 that is rotated by the AC power supplied from the inverter 12. In addition, when braking electric vehicle 100, motor 10 functions as a generator. In this case, the inverter 12 converts the AC power generated by the motor 10 into DC power suitable for charging the battery, and supplies the DC power to the battery.

  The control device 13 supplies a PWM signal for controlling the inverter 12 to the inverter 12. The PWM signal has a fundamental frequency and indicates an on / off time ratio for each period. The control device 13 determines the time ratio of the PWM signal according to a command value corresponding to information such as the accelerator opening. Further, the control device 13 determines a basic frequency (hereinafter referred to as a frequency) of the PWM signal by a frequency determination process described later.

  The signal supply device 14 supplies the control device 13 with a window state signal indicating the open / closed state of the driver's seat window 102a. The signal supply device 14 supplies a window state signal indicating a closed state to the control device 13 when the driver's seat window 102a is fully closed. The window state signal shown is supplied to the control device 13. The signal supply device 14 determines that it is fully closed based on a signal from a contact sensor (not shown) attached to the top of the driver's seat window 102a. The signal supply device 14 may acquire a signal indicating full close from a drive device that drives opening and closing of the driver's seat window 102a, and may determine that the signal is fully closed based on the signal.

  The signal supply device 14 may supply a window state signal indicating the open / closed state of both the driver's seat window 102a and the rear window 102b to the control device 13. In this case, the window state signal indicates the closed state when both the driver's seat window 102a and the rear window 102b are fully closed, and indicates the open state otherwise.

  With reference to FIG. 2, the content of the frequency determination process which the control apparatus 13 performs is demonstrated. In S10, the control device 13 determines whether or not the speed of the electric vehicle 100 is slower than a predetermined speed. The speed of electric vehicle 100 is calculated from an actual measurement value of a sensor capable of measuring the speed, the number of rotations of motor 10, or the like. The control device 13 proceeds to S12 when the speed is slower than the predetermined speed (YES in S10), and proceeds to S16 when the speed is equal to or higher than the predetermined speed (NO in S10). In S10, it may be determined whether or not the rotational speed of the motor 10 is smaller than a predetermined rotational speed.

  In S12, the control device 13 acquires a window state signal from the signal supply device 14, and determines whether the driver's seat window 102a is in an open state or a closed state based on the acquired window state signal. The control device 13 proceeds to S14 when the window state signal indicates the open state (YES in S12), and proceeds to S16 when the window state signal indicates the closed state (NO in S12). .

  In S14, the control device 13 determines the frequency of the PWM signal as the frequency F1 outside the audible frequency band. On the other hand, in S16, the control device 13 determines the frequency of the PWM signal to be a frequency F0 that is lower than the frequency F1 and within the audible frequency band. Here, the audible frequency band is generally a band of 20 Hz to 20 kHz. The frequency F1 is 20 kHz or more, and the frequency F0 is less than 20 kHz.

  The effect of the frequency determination process of FIG. 2 will be described. The satisfaction of both the conditions of S12 and S14 means that the electric vehicle 100 is traveling at a low speed and the driver's seat window 102a is in an open state. Since the driver's seat window 102a is open, the operation sound of the inverter 12 is transmitted to the driver sitting on the driver's seat 15a. However, since the frequency of the PWM signal is the frequency F1 outside the audible frequency band, the operating sound of the inverter 12 cannot be heard by the driver.

  Further, the determination of NO in S10 means that the electric vehicle 100 is traveling at a high speed. During high speed traveling, the level of noise other than the operation sound of the inverter 12 is high. If the driver's seat window 102a is open, the operation sound of the inverter 12 is transmitted to the driver. However, the driver can hardly hear the operation sound of the inverter 12 due to the influence of other noises.

  Further, the determination of NO in S12 means that the driver's seat window 102a or both the driver's seat window 102a and the rear window 102b are closed. Since the window is closed, the operation sound of the inverter 12 is not transmitted to the passenger.

  For example, a comparative example in which the process of S12 is not executed is assumed. In this comparative example, even when the driver's seat window 102a is closed, the control device 13 sets the frequency of the PWM signal to a frequency F1 higher than 20 kHz, which is the upper limit of the audible frequency band. This means that the frequency of the PWM signal is set to a high frequency even though the operation sound of the inverter 12 is not transmitted to the driver, which causes unnecessary loss in the inverter 12.

  On the other hand, according to the frequency determination process in FIG. 2, if the window is closed, the control device 13 sets the frequency of the PWM signal to a frequency F0 lower than 20 kHz which is the upper limit of the audible frequency band. Therefore, useless loss due to the inverter 12 can be omitted.

(Second embodiment)
The electric vehicle 100 of 2nd Example is demonstrated. The signal supply device 14 in the second embodiment supplies an ambient condition signal to the control device 13 in addition to the window state signal. The ambient state signal indicates whether or not there is a reflecting wall (for example, a guard rail) that reflects the operation sound of the inverter 12 around the electric vehicle 100. When the reflection wall exists, the operation sound of the inverter 12 is reflected by the reflection wall and transmitted to the electric vehicle 100. Not only the operation sound transmitted directly from the inverter 12 but also the reflected sound reflected by the reflecting wall can be transmitted to the occupant. Compared with the case where there is no reflecting wall, the level of the operating sound of the inverter 12 transmitted to the occupant becomes higher.

  Whether or not there is a reflection wall is determined by analyzing an image taken by an in-vehicle camera (not shown) and information from an in-vehicle millimeter wave radar (not shown). The signal supply device 14 supplies an ambient condition signal indicating that there is a reflection wall to the control device 13 when there is a reflection wall in the surroundings, while there is a reflection wall when there is no reflection wall in the surroundings. An ambient condition signal indicating that the control is not performed is supplied to the control device 13.

  With reference to FIG. 3, the content of the frequency determination process of 2nd Example is demonstrated. The frequency determination process in FIG. 3 is obtained by adding the process of S13 to the frequency determination process in FIG.

  In S12, the control device 13 proceeds to S13 when the window state signal indicates the open state (YES in S12). The processing when the window state signal indicates the closed state (NO in S12) is the same as in the first embodiment.

  In S <b> 13, the control device 13 determines whether there is a reflection wall in the surroundings based on the surrounding state signal supplied from the signal supply device 14. The control device 13 proceeds to S14 when the ambient condition signal indicates that a reflecting wall exists (YES in S13), and when the ambient condition signal indicates that no reflecting wall exists (NO in S13). , Go to S16.

  According to the above configuration, the frequency of the PWM signal becomes the frequency F1 that is outside the audible frequency band only when all the conditions of S12, S13, and S14 are satisfied. The condition for setting the frequency of the PWM signal to the frequency F1 is stricter than that in the first embodiment. In the second embodiment, loss countermeasures can be emphasized more than in the first embodiment.

(Modification)
The process of S13 of the second embodiment is not limited to the determination of whether or not a reflection wall exists. For example, in S13, the control device 13 may determine whether or not the level of noise other than the operation sound of the inverter 12 is equal to or lower than a predetermined level. The lower the noise level, the easier it is to hear the operation sound of the inverter 12. Noise other than the operating sound is measured by a vehicle-mounted noise sensor (not shown). In this modified example as well, the loss countermeasure can be more important than the first example, as in the second example.

  In S13, the control device 13 may determine whether or not the target torque indicated by the command value used for determining the time ratio of the PWM signal is equal to or greater than a predetermined torque. In situations where a large target torque is required, there is a high probability that the electric vehicle 100 is stopped or traveling at a very low speed. In this situation, the level of noise other than the operating sound of the inverter 12 is low. In this modified example as well, the loss countermeasure can be more important than the first example, as in the second example. Note that as the target torque increases, the current flowing from the inverter 12 to the motor 10 also increases. In S13, it may be determined whether or not the current is greater than or equal to a predetermined current.

  The frequency F1 and the frequency F0 are examples of the “first frequency” and the “second frequency”, respectively.

  Hereinafter, points to be noted regarding the technology shown in the embodiments will be described. The electric vehicle 100 may be a hybrid vehicle. The hybrid vehicle includes a power distribution mechanism that is connected to all of the engine, the motor, and the axle. The power distribution mechanism can not only transmit both engine power and motor power to the axle, but can also transmit engine power to both the motor and the axle. For this reason, in a hybrid vehicle, the vehicle speed is not proportional to the rotational speed of the motor. When the technique of the present application is adopted for a hybrid vehicle, it is not appropriate to make a determination based on the number of revolutions of the motor in S10, but it is appropriate to make a determination based on the vehicle speed.

  Moreover, in the hybrid vehicle, the inverter 12 can operate even when the vehicle is stopped (a state where the ignition switch is stopped with the ignition switch turned on). “The vehicle speed is slower than a predetermined speed” includes not only a state where the vehicle is traveling at a low speed but also a state where the vehicle is stopped.

  The closed state is not limited to the state where the driver's seat window 102a is fully closed. For example, the closed state may be a state in which the driver's seat window 102a is closed at a predetermined ratio (for example, 90%) or more, and the open state may be a state in which the driver's seat window 102a is closed at a predetermined ratio or less.

  Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or the drawings can achieve a plurality of objects at the same time, and has technical usefulness by achieving one of the objects.

10: Motor 12: Inverter 13: Control device 14: Signal supply device 15a: Driver's seat 15b: Rear seat 100: Electric vehicle 101: Car body 102a: Driver's seat window 102b: Rear window 103: Front compartment F0: Frequency F1: Frequency

Claims (1)

An in-vehicle inverter,
A controller for supplying a PWM signal for controlling the inverter to the inverter;
A signal supply device that supplies a window state signal indicating an open / closed state of a window of the vehicle body to the control device;
With
The control device determines the frequency of the PWM signal,
When the vehicle speed is slower than a predetermined speed and the condition that the window state signal indicates the open state is satisfied, the first frequency is outside the audible frequency band,
When the condition is not satisfied, the electric vehicle having a second frequency lower than the first frequency and within an audible frequency band.

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