JP2011109883A - Power converter for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem wherein a noise level is too low to be detected by a pedestrian in a vehicle actuated by using a power converter in comparison with general internal combustion engine vehicles, by generating sound large enough to be detected by the pedestrian in approaching the vehicle; and also to solve the problem without the need for any additional equipment. <P>SOLUTION: A voltage-mode power converter using a pulse-width modulation lowers its switching frequency to actuate electric equipment when the pedestrian is near the vehicle, and lets the pedestrian detect the approach by lowering the frequency of the operation sound to an audible frequency band. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a power conversion device mounted on a vehicle, and particularly notifies a pedestrian of the approach of an automobile.

The prior art will be described with reference to FIGS.

  As shown in FIG. 2, a power conversion device 10 mounted on a vehicle such as an electric vehicle, a hybrid vehicle, or a railway vehicle includes a DC power supply 16 and its DC voltage converted into a power conversion circuit 3 such as an inverter circuit or a chopper circuit. A configuration is generally used in which an electric device such as an electric motor as a load 4 is driven by converting the voltage into an arbitrary voltage and frequency.

  The power converter uses pulse width modulation control. In the pulse width modulation control, an arbitrary frequency and voltage are obtained by comparing the triangular wave carrier shown in FIG. 3 with a voltage command. This triangular wave carrier is generally several hundred Hz to several tens kHz.

  FIG. 4 shows a block diagram of a general voltage type power converter. The carrier frequency command fc is input to the carrier generator 5 to generate a triangular wave. The generated triangular wave is input to the carrier comparator 6 for each phase of U, V, W phase, and compared with the voltage command VU, VV, VW of each phase. Is high, 1 is input to the power conversion circuit 3. The power conversion circuit 3 outputs a high-side voltage of the DC power source if the carrier command is 1 to the load 4 and a low-side voltage if the carrier command is 0. For this reason, the output voltage includes a frequency component of a triangular wave carrier.

  A general power converter is driven by a triangular wave carrier comparison shown in FIG. The output current includes this triangular wave carrier frequency component. Thereby, the sound of a triangular wave carrier frequency component is generated from the electric motor or reactor of the vehicle drive system. For example, the power converter of Patent Document 1 is also driven by this method.

JP-A-2005-130599 JP 7-205753 A JP2009-142017

  In a vehicle that obtains power by using a power conversion device, there is a problem that a pedestrian cannot sense because the noise level is too low when compared to a general internal combustion locomotive when approaching a pedestrian. This problem is particularly noticeable in elderly people who are deaf or deaf.

  For example, Patent Document 2 discloses a countermeasure against this problem. As shown in FIG. 5, when the vehicle body 7 approaches the pedestrian 9, an alarm sound is generated by the warning device 8 using the pedestrian detection device 1. A pedestrian detection device here includes a driver.

  However, in such a method, a warning system must be newly installed. Warning systems are always energy consuming and therefore less energy efficient than vehicles without warning systems. In addition, additional costs for installing a sound generator and the like are incurred.

  Further, as disclosed in Patent Document 3, there is an example in which a warning system is installed outside the vehicle body and is operated by wind pressure during traveling. This method increases the air resistance of the vehicle and reduces energy efficiency. This also incurs additional costs for installing a warning system.

  According to the invention of claim 1, in the voltage type power conversion device using pulse width modulation mounted on the vehicle, it satisfies both or at least one of when the pedestrian is near the vehicle and when the vehicle speed is lower than the reference. When this happens, the vehicle power conversion device is characterized in that the switching frequency of the vehicle power conversion device is reduced.

  According to the invention of claim 2, in the vehicle power conversion device, the means for detecting a nearby pedestrian is provided, and the detection signal is input to the vehicle power conversion device, thereby switching the vehicle power conversion device. A power converter for a vehicle, characterized in that the frequency is lowered.

  According to the invention of claim 3, the vehicle power conversion device according to claim 1, wherein the switching frequency of the vehicle power conversion device is lowered when the traveling speed of the vehicle is lower than a reference. apparatus.

  According to a fourth aspect of the present invention, in the vehicle power conversion device according to any one of the first to third aspects, wherein the switching command for the power conversion device is generated by the triangular wave carrier comparison, the switching frequency is reduced by reducing the frequency of the triangular wave carrier. The power converter for vehicles characterized by reducing.

  According to a fifth aspect of the present invention, in the vehicle power converter according to any one of the first to fourth aspects, the power converter is an inverter circuit and drives an AC motor.

  According to a sixth aspect of the present invention, in the vehicle power converter according to any one of the first to fourth aspects, the power converter is a chopper circuit and drives a direct current motor.

  According to invention of Claim 7, the rectification | straightening reactor is connected to the power converter device for vehicles in any one of Claim 1 to 4, The power converter device characterized by the above-mentioned.

  According to the invention of claim 8, a power conversion apparatus, wherein the step-up / step-down reactor is connected to the vehicle power conversion apparatus of any one of claims 1 to 4.

  According to invention of Claim 9, in the vehicle power converter device of Claim 4, a vehicle is driven using an electric motor, The vehicle power converter device characterized by the above-mentioned.

  According to a tenth aspect of the present invention, in the vehicle power conversion device according to the fourth aspect, the vehicle is driven by using the electric motor and the internal combustion engine in combination.

  It is possible to generate a sound that can be detected by a pedestrian without adding new hardware that generates a warning sound.

It is an example of the power converter device for vehicles of the present invention. It is an example of the normal motor drive apparatus for vehicles. It is an example of the switching command generation by a triangular wave carrier comparison. It is an example of a block diagram of a general voltage type power converter. It is a figure explaining the pedestrian detection by a prior art. It is an example of the operation | movement when the pedestrian in Example 1 approaches a vehicle. It is description of the operation | movement which reduces the carrier frequency in Example 1. FIG. It is an example of the power converter device for vehicles in Example 2. FIG. FIG. 6 is a diagram illustrating an example of a motor drive system according to a third embodiment. FIG. 10 is a diagram illustrating an example of an electric vehicle in a fourth embodiment. FIG. 10 is a diagram illustrating an example of a hybrid vehicle in a fifth embodiment.

  Preferred embodiments of the invention are illustrated using the following examples. The embodiment of the present invention may be a pure electric vehicle using only electric power or a hybrid vehicle using an internal combustion engine or the like together.

  Referring to FIGS. 1, 6 and 7, a first embodiment of the present invention will be described. However, the same parts as the conventional technique are omitted.

  FIG. 6 shows an operation example when a pedestrian approaches the vehicle. When a pedestrian 9 approaches the vehicle 7, the pedestrian detection device 1 gives an appropriate detection signal to the power conversion device 10. As the pedestrian detection device 1, for example, a sonar or an image recognition device that is conventionally mounted in a vehicle or the like can be used.

  The block diagram of the power converter device with which the pedestrian detection apparatus was connected to FIG. 1 is shown.

  A signal commanded from the pedestrian detection device 1 is input to the carrier frequency command device 2. Here, the carrier frequency commander 2 drops the carrier frequency command commanded to the carrier generator 5 to a frequency that can be heard by human ears, such as a frequency of 1000 Hz or less, among the audible frequencies of 20 Hz to 15000 Hz.

  FIG. 7 shows an example of reducing the carrier frequency.

  The carrier frequency f1 is a carrier frequency in a normal state. Generally, this frequency is about 1000 Hz to several tens of kHz. When a pedestrian is detected, the switching frequency falls to f2 which is an audible frequency band.

  As shown in the prior art, it is known that noise of a carrier frequency component is generated in a voltage type power converter using pulse width modulation. In addition, the sound generated when the carrier frequency is lower becomes louder. Therefore, by reducing the carrier frequency from f1 to f2, it is possible to generate a sound that can be sufficiently heard by human ears from the vehicle, and to make the pedestrian sense the approach of the vehicle.

  A second embodiment of the invention of claim 3 will be described with reference to FIG. The same parts as those in the first embodiment are omitted.

An embodiment when the speed of the vehicle falls below the reference will be described with reference to FIG. When the vehicle approaches the pedestrian, the driver steps on the brake and the speed decreases. The speed detection device 11 detects that the brake stepping speed has become lower than the reference. A detection signal is sent to the carrier frequency command device 2, and the carrier frequency command device drops the carrier frequency command to a frequency within a range that can be heard by human ears. Thereby, it is possible to make the pedestrian sense the approach of the vehicle.

  Embodiment 3 of the invention of claims 5 to 8 will be described with reference to FIG. The same parts as those in Examples 1 and 2 are omitted.

  FIG. 9 is a diagram of a motor drive composed of a chopper circuit 12, an inverter circuit 14, and an electric motor 15. The reactor 13 is a reactor for a boost chopper.

  When the chopper circuit 12 operates, the reactor 13 vibrates and generates sound. Since the frequency of the sound generated at this time is a switching frequency component of the chopper circuit 12, when the frequency is decreased, a sound having a height that can be perceived by humans is generated.

  Next, when the inverter circuit 14 operates, the electric motor 15 and the smoothing reactor in the inverter circuit 14 vibrate and generate sound. Since the frequency of the sound generated at this time is a switching frequency component of the inverter circuit 14, when the frequency is decreased, a sound having a height that can be perceived by humans is generated.

  Example 4 of Claim 9 is shown using FIG. The same parts as those in Examples 1 to 3 are omitted.

  FIG. 10 is a system diagram of a pure electric vehicle. Embodiments 1 to 3 can be applied because the system is operated by a power converter 10 such as an inverter and an electric device such as an electric motor 15.

  Example 5 of Claim 10 is shown using FIG. The same parts as those in Examples 1 to 4 are omitted.

  FIG. 11 is a system diagram of an example of a hybrid vehicle using both electric power and an internal combustion engine. Embodiments 1 to 3 can be applied because the system is operated by a power converter 10 such as an inverter and an electric device such as an electric motor 15.

  The present invention is effective for a power converter for an electric vehicle. Moreover, since it can implement | achieve, without adding the hardware of the existing vehicle, it is very effective.

DESCRIPTION OF SYMBOLS 1 Pedestrian detection apparatus 2 Carrier frequency command device 3 Power conversion circuit 4 Load 5 Carrier generator 6 Carrier comparator 7 Vehicle 8 Warning generating device 9 Pedestrian 10 Power conversion device 11 Speed detection device 12 Chopper circuit 13 Reactor 14 Inverter circuit 15 Electric motor 16 DC power supply

Claims (10)

  In a voltage type power conversion device using pulse width modulation mounted on a vehicle, when the pedestrian is near the vehicle and / or when the vehicle speed is lower than the reference, the vehicle power conversion device The vehicle power converter device characterized by lowering the switching frequency.   The vehicle power conversion device according to claim 1, wherein means for detecting a nearby pedestrian is provided, and the switching frequency of the vehicle power conversion device is reduced by inputting a detection signal to the vehicle power conversion device. A power conversion device for vehicles.   2. The vehicle power converter according to claim 1, wherein the switching frequency of the vehicle power converter is lowered when the traveling speed of the vehicle is lower than a reference.   The vehicle power converter according to any one of claims 1 to 3, wherein the switching command of the power converter is generated by a triangular wave carrier comparison, wherein the switching frequency is lowered by lowering the frequency of the triangular wave carrier. Power converter.   5. The vehicle power converter according to claim 1, wherein the vehicle power converter is an inverter circuit and drives an AC motor.   5. The vehicular power conversion device according to claim 1, wherein the vehicular power conversion device is a chopper circuit and drives a DC motor.   A rectifying reactor is connected to the vehicular power converter according to any one of claims 1 to 4, wherein the vehicular power converter.   5. A vehicle power conversion device, wherein a step-up / step-down reactor is connected to the vehicle power conversion device according to claim 1.   5. The vehicle power conversion device according to claim 4, wherein the vehicle is driven using an electric motor. 5. The vehicle power conversion device according to claim 4, wherein the vehicle is driven by using an electric motor and an internal combustion engine in combination.

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