JP4285171B2 - Alternator abnormality detection apparatus and method - Google Patents

Description

  The present invention relates to an apparatus and method for detecting an abnormality (including a sign) of an alternator (alternator), and more particularly, to an apparatus and method mounted on a vehicle.

  Conventionally, the ripple included in the output voltage of the rectifier is detected, the number of ripples within a predetermined period related to the basic cycle of the power generation operation is counted, and when the number of ripples is less than the predetermined number, abnormality determination is performed, The alarm lamp is turned on by driving (see, for example, Patent Document 1). Also, the comparator compares the armature phase output voltage waveform and the full-wave rectified generator output voltage divided by a predetermined voltage division ratio, and outputs the output waveform as a one-phase output at the divided voltage level. The duty when the voltage waveform is cut is detected, and it is determined whether or not the duty value is within a predetermined range. Then, the abnormality is detected in one rectifier diode or two rectifier diodes in different phases of all phases of the rectifier by setting the determination criterion to a predetermined range centered on 50% duty (for example, , See Patent Document 2).

Japanese Patent Laid-Open No. 2003-61260

JP-A-8-65914

  In Patent Document 1, since it is necessary to sample at a high speed in order to count ripples, a high-performance ECU is required.

  In Patent Document 2, it is difficult to detect a failure of the armature winding.

  An object of the present invention is to provide an apparatus and a method for detecting an abnormality of an alternator with a simple circuit configuration that does not require a high-performance processing apparatus.

  The present invention detects the abnormality of the alternator by filtering the output voltage of the battery terminal of the alternator in a specific frequency band and determining whether the filtered output voltage is equal to or higher than a specific threshold value. Further preferably, in the present invention, an abnormal sign is determined by specifying a peak frequency of the output voltage by using the filter characteristic used for filtering, and monitoring and analyzing a deviation from the peak frequency at the normal time.

  According to the present invention, since it is possible to immediately detect an abnormality of the alternator, a warning light or car navigation system on the front panel is displayed before symptoms such as battery deterioration or engine stop due to the alternator power generation stoppage. Thus, it is possible to take safety measures such as notifying the driver of an abnormality via the in-vehicle terminal. Also, by using wireless communication devices such as mobile phones, it is possible to notify the detected abnormal signal to dealers, automobile manufacturers, parts manufacturers, etc., so early measures such as procurement and collection of parts are possible. Can be applied. Further, by predicting the abnormality of the alternator, it is possible to replace parts before symptoms such as deterioration of the battery and engine stop associated with a decrease in the power generation capability of the alternator occur. In addition, it is possible for automobile manufacturers and parts manufacturers to verify the abnormality of the alternator using parts having a short life, and the verification results can be reflected in the design and development of the next product.

  The best carrying for carrying out the present invention will be described.

  FIG. 1 is a configuration example in which an in-vehicle diagnostic apparatus equipped with an alternator abnormality detection method according to the present invention is applied to an in-vehicle system of a passenger car. The in-vehicle diagnostic device 105 is connected to the battery terminal of the alternator 103, the warning light 104, and an electric wire, and is connected to a vehicle LAN such as a car navigation system 101, an engine control unit 102 (hereinafter referred to as ECU), and a CAN (Control Area Network). (Local Area Network). The warning light 104 is for displaying the diagnosis result of the in-vehicle diagnosis device 105. For example, when an abnormality of the alternator is detected, the warning light 104 is on a front panel provided with instruments such as a speed meter and an engine speed meter. The red lamp lights up. The car navigation system 101 is connected to a mobile phone 106, and the diagnosis result of the in-vehicle diagnostic device 105 is notified to an external system such as a dealer, an automobile manufacturer, or a parts manufacturer via the car navigation system 101 and the mobile phone 106. Further, the diagnosis result of the in-vehicle diagnosis device 105 may be displayed on the terminal screen of the car navigation system 101. The ECU 102 is a vehicle control processing device that controls the engine using powertrain sensor information such as an accelerator opening sensor, an air amount sensor, and a crank angle sensor, and notifies the in-vehicle diagnosis device 105 of the current engine speed. In the configuration example of FIG. 1, the in-vehicle diagnosis device 105 and the ECU 102 are described as different devices, but the function of the in-vehicle diagnosis device 105 may be incorporated in the ECU 102. In this case, the alternator 103 and the warning lamp 104 are connected to the ECU 102.

  FIG. 2 is a configuration example of the in-vehicle diagnostic device 105. The in-vehicle diagnosis device 105 includes a processor 201 for performing operations such as program execution, a ROM 202 for storing basic programs and basic data such as an OS (Operating System), a processing area during program execution, and a temporary storage area for data. A RAM 203 to be used, a communication interface 204 for connecting to the in-vehicle LAN 100, and an external device interface 205 for connecting to the warning light 104, these components can exchange data with each other via the bus 200. . The program executed by the processor 201 is a diagnostic program to which the present invention is applied. The processor 201 and the battery terminal 206 are connected via an analog terminal 207, and a diagnostic program executed by the processor 201 executes a diagnostic process after converting an analog signal received from the analog terminal 207 into a digital signal. FIG. 2 shows a configuration in which the battery terminal 206 and the analog terminal 207 are directly connected. However, in order to reduce the processing load and reduce the cost of the in-vehicle diagnostic apparatus, a partial function of the diagnostic program executed in the processor 201 ( For example, an analog device in which a filter processing function described below is mounted may be connected between both terminals.

  FIG. 3 is a three-phase AC full-wave rectifier circuit diagram 300 of the alternator targeted by the present invention. The alternator 105 generates an electromotive force by the rotation of the three coils 303, converts the generated three-phase alternating current into direct current using a diode, and supplies power to the battery and the electric load. On the other hand, since the alternator operates at a high temperature of about 90 ° C., the diodes 301 and 302 may be thermally deteriorated due to the high temperature. As the diode's thermal degradation progresses, the diode connection becomes open or short-circuited. As a result, the power generated by the alternator decreases, and eventually the power supply to the battery and other electric loads is interrupted. Trigger events such as deterioration and engine shutdown. The present invention relates to a detection method for detecting thermal deterioration of the diode at an early stage and enabling countermeasures to be taken before the event surface.

  FIG. 4 shows an output voltage waveform of the battery terminal 206 when the rotational speed of the alternator 103 is 2000 [rpm], with the horizontal axis indicating elapsed time (seconds) and the vertical axis indicating output voltage (V). FIG. (A) 401 shows a waveform when the diodes 301 and 302 are normal (hereinafter, referred to as a normal voltage waveform), which is a waveform with an amplitude of about 1 V and a constant cycle. In contrast, in FIGS. (B) to (F) (402 to 406), when the diode 301 is open and short (FIG. (C) 403, FIG. (E) 405), the diode 302 is open and short (FIG. (D). ) 404, FIG. (F) 406), the waveforms when the diode 301 is open and the diode 302 is shorted (FIG. (B) 402) (hereinafter, the waveforms of FIGS. (B) to (F) are abnormal voltage waveforms). It can be seen that this is clearly different from the normal voltage waveform diagram (A) 401. In the normal voltage waveform and the abnormal voltage waveform, the difference between the maximum voltage value and the minimum voltage value differs by about three times or more, and the period of the waveform is longer in the abnormal voltage waveform than in the normal voltage waveform. The abnormality of the alternator is detected using the difference between the normal voltage waveform and abnormal voltage waveform.

  FIG. 5 shows a functional configuration example of the in-vehicle diagnostic device 105. The in-vehicle diagnosis apparatus 105 includes an input unit 503, an abnormality determination processing unit 502, and an output unit 501. The input unit 503 transmits the output voltage signal received from the battery terminal 206 of the alternator 105 to the abnormality determination processing unit 502. The abnormality determination processing unit 502 determines whether or not there is an abnormality based on the voltage signal received from the input unit 503, and notifies the output unit 501 of the determination result when determining that there is an abnormality. The output unit 501 notifies the determination result received from the abnormality determination processing unit 502 to external devices such as the warning lamp 104 and the car navigation system 101. Detailed processing of the abnormality determination processing unit 502 will be described with reference to FIG.

  6A is a processing flow of the abnormality determination processing unit 502, and FIG. 6B is an abnormality determination table for the abnormality determination processing unit 502 to determine abnormality. When the abnormality determination processing unit 502 receives the output voltage signal from the battery terminal 206 of the alternator 105 (step 601), the abnormality determination table 610 determines whether or not the difference between the maximum value and the minimum value of the output voltage signal is equal to or greater than a threshold value. It judges based on (step 602), when it is more than a threshold, it judges with it being abnormal (step 603), and notifies the output part 601 of a judgment result. The abnormality determination table 610 indicates a normal voltage difference 611 indicating the difference between the normal maximum voltage value and the minimum voltage value, and a threshold of the difference between the maximum voltage value and the minimum voltage value for determining whether or not there is an abnormality. An abnormality determination threshold 612 is configured. In the example of FIG. 6B, the normal voltage difference is set to 1V, and the abnormality determination threshold is set to about 3V (a range of 2.5V to 3.5V, a range of 15% above and below 15V with reference to 3V). Although the basic setting values of the abnormality determination table 610 are determined by the time of product shipment, registration to the table may be performed by a mechanic such as a dealer using a maintenance tool or the like after the vehicle is shipped. The abnormality determination threshold should be set by the voltage difference at the time of abnormality of the alternator to be diagnosed. However, when the voltage difference at the time of abnormality cannot be confirmed in advance, it is about three times the voltage difference at normal time based on FIG. It is desirable to set it to a level (range of 2.5 to 3.5 times, and a range of 15% up and down with reference to 3 times). Further, the normal voltage difference 611 may be updated as needed as a normal voltage difference 611 that is a voltage difference received from the input unit when the abnormality determination processing unit 502 does not determine that there is an abnormality. In this case, it is necessary to design so that the abnormality determination threshold 612 is also updated as the normal voltage difference 611 is updated.

  As described above, according to the first embodiment, the in-vehicle diagnostic apparatus 105 can detect an abnormality of the alternator based on the difference between the maximum value and the minimum value of the output voltage of the battery terminal of the alternator. It is possible to notify the driver, dealer, automobile manufacturer, etc. of the abnormality before an event such as an engine stoppage occurs.

  In the first embodiment, the method for determining an abnormality based on only the difference between the maximum value and the minimum value of the output voltage of the battery terminal of the alternator has been described. Since power generation is performed, when the influence of the electrical load is large, there may be a case where the voltage difference suddenly increases. As a result, there is a possibility of misdiagnosis such as determining normal or abnormal. In order to lose such misdiagnosis and detect an abnormality more accurately, an abnormality detection method focusing on the periodicity of the abnormal voltage waveform shown in FIG. 4 will be described as a modification of the first embodiment.

  FIG. 7 shows the result of frequency analysis of each output voltage waveform at the battery terminal of the alternator shown in FIG. 4, and the horizontal axis shows the frequency and the vertical axis shows the ratio when the value of the strongest frequency component is 100. . FIG. 701 shows a frequency analysis result (hereinafter referred to as a normal frequency analysis result) at the output voltage when the diode is normal, and shows a peak at a frequency of 1.2 Khz. On the other hand, in FIGS. (B) to (F) (702 to 706), when the diode 301 is open and short (FIG. (C) 703, FIG. (E) 705), the diode 302 is open and short (FIG. D) 704, FIG. (F) 706), the frequency analysis result when the diode 301 is open and the diode 302 is shorted (FIG. (B) 702) (hereinafter, the waveforms in FIGS. (B) to (F) are abnormal) It is understood that all of the abnormal frequency analysis results peak at 1 Khz or less compared to the normal frequency analysis results. In the present invention, in addition to the first embodiment, alternator abnormality detection is performed using the difference between the normal frequency analysis result and the abnormal frequency analysis result.

  FIG. 8 shows a functional configuration example of the in-vehicle diagnostic apparatus 105. The in-vehicle diagnosis apparatus 105 includes an input unit 804, a filter processing unit 803, an abnormality determination processing unit 802, and an output unit 801. The output voltage signal received from the battery terminal 206 of the input unit 804 and the alternator 105 is transmitted to the filter processing unit 803. The filter processing unit 803 filters the voltage signal received from the input unit 804 with a specific frequency band, and transmits only the filtered voltage signal to the abnormality determination processing unit 802. Further, the filter processing unit 803 can receive the current engine speed from the ECU 102 and determine a frequency band to be filtered based on the engine speed. The abnormality determination processing unit 802 determines whether or not there is an abnormality based on the voltage signal received from the filter processing unit 803, and notifies the output unit 501 of the determination result (abnormality) when determining that there is an abnormality. The output unit 801 notifies the determination result received from the abnormality determination processing unit 502 to external devices such as the warning lamp 104 and the car navigation system 101. Detailed processing of the filter processing unit 803 and the abnormality determination processing unit 802 will be described with reference to FIGS. 9 and 10. In addition, normal may be output as a determination result instead of abnormality.

  FIG. 9 is a processing flow of the filter processing unit 803 and the abnormality determination processing unit 802 of the in-vehicle diagnostic apparatus 105, and FIG. 10 is a filter frequency table for the filter processing unit 803 to determine the filter frequency.

  When the output voltage signal of the battery terminal 206 of the alternator 103 is input to the filter processing unit 803 (step 901), the filter processing unit 803 outputs the output voltage at the filter frequency 1004 determined based on the current engine speed input from the ECU 102 and the filter frequency table 1000. The signal is filtered (step 902), and the filtered output voltage signal (hereinafter referred to as a filter signal) is transmitted to the abnormality determination processing unit 802.

The filter frequency table 1000 includes an item 1001, an engine speed 1002, an alternator speed 1003, and a filter frequency 1004, and the items include a reference value 1005 and a correction value 1006.
The reference value 1005 is a value obtained by statically holding a filter frequency at a specific alternator speed such as an engine idle state, and is determined by the time of product shipment. Registration of the reference value in the filter frequency table may be performed by a mechanic such as a dealer.

The reference value 1005 is preferably determined based on the normal frequency analysis result and the abnormal frequency analysis result at the specific rotation speed of the alternator, but the normal and abnormal frequencies for all alternators. When the analysis result cannot be confirmed, data of a normal peak frequency B [Khz] analyzed at a specific alternator rotation speed A [rpm] as shown in FIG. 7 is prepared in advance. The peak frequency X [Khz] at the normal time of the output voltage signal of the battery terminal acquired at an arbitrary engine speed may be determined using A and B. For example, when the peak frequency X [Khz] is acquired when the engine speed is Y [rpm], the filter frequency 1004 of the reference value 1005 is
X × 10% or more, X × 70% or less
X = {B [Khz] × (Z [rpm] / A [rpm])} (Formula 1)
It becomes. However, Z [rpm] is the number of rotations of the alternator.
ρ (ratio of alternator speed and engine speed) × Y [rpm] (Expression 2)
(If the rotation speed of the alternator can be acquired from the ECU, the rotation speed of the alternator acquired from the ECU may be directly substituted into (Equation 1)). The numerical value of “10% or more and 70% or less” in (Expression 1) is a value determined from the frequency analysis result shown in FIG.

  In the example of FIG. 10, the engine speed 1002 of the reference value 1005 is 700 [rpm], the alternator speed 1003 is 2100 [rpm], and the filter frequency is 0.1 to 0.8 [Khz].

9 and 10 describe the case where the filter frequency is filtered in a certain frequency band (band pass filter), but the filter frequency may be filtered in a band (a low pass filter) below a specific frequency. In this case, (Equation 1) is
X × 70% or less
X = {B [Khz] × (Z [rpm] / A [rpm])} (Expression 3)
It will be represented by

9 and 10 describe the case of filtering in the frequency band for detecting abnormality from the output voltage signal of the battery terminal, but filtering in the frequency band for detecting whether it is normal or not is performed. Also good. In this case, (Equation 1) is based on the frequency analysis result of FIG. 7 X × 80% or more and X × 120% or less X = B [Khz] × (Z [rpm] / A [rpm]) (Equation 4 )
Or
X × 80% or more X = B [Khz] × (Z [rpm] / A [rpm]) (Formula 5)
It will be represented by

  When (Equation 4) and (Equation 5) are applied to the filter frequency table, the abnormality determination processing unit 802 determines whether it is normal.

  The correction value 1006 is a value obtained by dynamically correcting the filter frequency based on the reference value 1005 at an arbitrary engine speed such as when the vehicle is running. The engine speed 1002 is a value acquired from the ECU 102, and the alternator speed 1003 is The filter frequency 1003 is a value obtained by (Equation 1) with the value obtained based on (Equation 2) (or the value obtained from the ECU 102).

  The correction value 1006 does not always have to be registered in the table. If the correction value 1006 is not registered in the filter frequency table 1000, the filter process may be performed only at the engine speed registered with the reference value 1000. .

  The abnormality determination processing unit 802 determines whether the difference between the maximum voltage value and the minimum voltage value of the filter signal filtered by the filter processing unit 803 is greater than or equal to a threshold value based on the abnormality determination table 610 (step 903). , It is determined as abnormal (step 904), and the determination result is notified to the output unit 801.

  In the present embodiment, the case where processing is performed in the in-vehicle diagnostic apparatus shown in FIG. 2 has been described. However, in order to reduce the processing load and cost of the in-vehicle diagnostic apparatus, the filter processing unit 803 uses the reference value of the filter frequency table. The filter may be mounted as an analog filter device (hereinafter referred to as an analog device) that filters the output voltage signal of the battery terminal at a filter frequency to be set in (1). When the filter processing unit is implemented by an analog device, the abnormality determination processing unit performs the abnormality determination processing only at the engine speed set by the reference value of the filter processing unit, and the engine from the ECU 102 The rotation number is notified to the abnormality determination processing unit.

  As described above, according to the modification of the first embodiment, the filter processing unit that filters the output voltage signal of the battery terminal of the alternator based on the filter frequency table and the filter signal input from the filter processing unit are determined to be abnormal. By providing an in-vehicle diagnosis device with an abnormality determination processing unit that performs abnormality determination based on the table, the output voltage signal of the battery terminal suddenly changes abnormally due to the influence of power generation on the other electrical load of the alternator. Even if it occurs, it is possible to detect an abnormality without being affected by it.

  In the first embodiment and the modification of the first embodiment, the abnormality detection method for detecting an abnormality early based on the output voltage signal of the battery terminal of the alternator has been described. However, depending on the state of the abnormality, the power generation capability of the alternator is rapidly reduced. Therefore, when such a state occurs, symptoms such as battery deterioration and engine stop immediately come to the surface, and it becomes difficult to ensure the safety of the driver. In order to avoid such a situation, an abnormality sign detection method for detecting a sign of abnormality before the alternator becomes abnormal will be described as a second embodiment.

  A functional configuration example of the in-vehicle diagnosis device 105 described in the second embodiment is the same as that in FIG. FIG. 11 is a processing flow of the filter processing unit 803 and the abnormality determination processing unit 802 of the in-vehicle diagnostic apparatus 105, and FIG. 12A is a filter characteristic used by the filter processing unit 803 to filter the output voltage signal of the battery terminal. FIG. 12B is an abnormality sign determination table for the abnormality determination processing unit 802 to determine an abnormality sign.

  When the output voltage signal of the battery terminal 206 of the alternator 103 is input to the filter processing unit 803 (step 1101), the filter processing unit 803 uses the output frequency at the filter frequency determined based on the current engine speed input from the ECU 102 and the filter frequency table 1000. The signal is filtered (step 1102), and the filter signal is transmitted to the abnormality determination processing unit 802. The filter frequency table 1000 used in step 1102 is shown in FIG. 10. In this step, the frequency band (Equation 4 or 5) for detecting normality from the output voltage signal at the battery terminal is used.

  The abnormality determination processing unit 802 determines whether it is normal based on the difference between the maximum voltage value and the minimum voltage value of the filter signal filtered by the filter processing unit 803. The abnormality determination threshold 612 of the abnormality determination table 610 described in FIG. 6 is used to determine whether or not there is an abnormality. As described above, it is desirable that the abnormality determination threshold 612 be set to about three times the normal voltage difference 611. However, as a threshold value setting for determining whether or not it is normal, it is desirable to set 1 to 1.5 times the normal voltage difference 611 as the threshold value. Therefore, the abnormality determination processing unit 802 determines whether the difference between the maximum voltage value and the minimum voltage value of the filter signal filtered by the filter processing unit 803 is within a range of, for example, 1V to 1.5V based on the abnormality determination table 610. (Step 1103), if the threshold range is exceeded, it is determined that the alternator is abnormal (step 1107). If it is within the threshold range, the peak frequency of the filter signal is specified based on the filter characteristics 1200. (Step 1104). For example, when the filter characteristic is a function V = F (X) and the voltage value of the filter signal is represented by Vin, X that satisfies Vin = F (X) is the peak frequency. FIG. 12A is a filter characteristic diagram in which the vertical axis represents the output voltage (V) 1202 of the filter signal and the horizontal axis represents the peak frequency (KHz) 1201, and the center frequency is 1.2 KHz when the engine speed is 700 rpm. This is an example in which the maximum value is obtained and the minimum value is obtained at 1.0 KHz and 1.4 KHz.

  When the peak frequency of the filter signal is specified based on the filter characteristic 1200, it is determined whether or not there is an abnormality sign based on the abnormality sign determination table 1210 (step 1106). The abnormality sign determination table 1210 includes a sign determination frequency 1211. The sign determination frequency 1211 is a threshold value for determining a deviation from the center frequency of the filter characteristic 1200. When the sign determination frequency 1211 is largely deviated from the registered threshold value, it is determined as an abnormal sign (step 1106). In the example of FIG. 12, the peak frequency when the Vf filter signal is input is X = 1.1 KHz, which is a value equal to or greater than the threshold value registered in the abnormality sign determination table. Therefore, it will be determined that the alternator is abnormal. In the example of FIG. 12B, the sign determination frequency 1211 is set to 100 Hz, but the sign determination frequency may be determined from the variation of the peak frequency band in the output voltage signal of the battery terminal of the alternator at the normal time. Good. Further, the sign determination frequency 1211 of the abnormality sign determination table 1210 is determined by the time of product shipment. Registration to the abnormality sign determination table is performed by a mechanic such as a dealer using a maintenance tool or the like after the vehicle is shipped. Also good. Further, in this embodiment, it is determined whether or not there is an abnormality sign based on the threshold value registered in the abnormality sign determination table, but the peak frequency of the filter signal is stored as needed, and the peak frequency stored for a certain period is stored. If it changes constantly, it may be determined as an abnormal sign.

  As described above, according to the second embodiment, a sign of abnormality can be detected based on the shift of the peak frequency of the filter signal, so that the parts are replaced before symptoms such as battery deterioration or engine stop occur. can do. In addition, since it is possible to collect the alternator immediately before the occurrence of the abnormality, it is possible to actually verify the abnormality that had only occurred in the market in the past and reflect the verification result in the design and development of the next product. .

1 is an overall configuration diagram of an in-vehicle system provided with an in-vehicle diagnosis device according to the present invention. It is an internal block diagram of the vehicle-mounted diagnostic apparatus in this invention. It is a three-phase alternating current full wave rectification circuit diagram of the alternator made into object in the present invention. It is a wave form diagram of the output voltage of the battery terminal at the time of the diode of the alternator made into object in this invention at the time of normality and abnormality. It is an internal function structure of the vehicle-mounted diagnostic apparatus in Example 1 of this invention. It is an example of a structure of the abnormality determination table for performing the internal processing flow and abnormality determination of the vehicle-mounted diagnostic apparatus in Example 1 of this invention. It is a frequency characteristic figure of the output voltage of the battery terminal when the diode of the alternator targeted in the present invention is normal and abnormal. It is an internal function structure of the vehicle-mounted diagnostic apparatus in the modification of Example 1 of this invention. It is an internal processing flow of the vehicle-mounted diagnostic apparatus in the modification of Example 1 of this invention. It is a filter frequency table structural example for determining a filter frequency in the modification of Example 1 of this invention. It is an internal processing flow of the vehicle-mounted diagnostic apparatus in Example 2 of this invention. FIG. 10 is a configuration example of a filter characteristic diagram and an abnormality sign determination table for performing abnormality sign determination in Example 2 of the present invention.

Explanation of symbols

100 in-car LAN
101 car navigation system 102 ECU
103 Alternator 104 Warning light 105 In-vehicle diagnostic device 106 Mobile phone 200 Bus 201 Processor 202 ROM
203 RAM
204 Communication interface 205 External device interface

Claims (12)

  In an apparatus for detecting an abnormality of an alternator,
  Input means for inputting the output voltage of the alternator;
  Filter means for filtering the output voltage of the alternator in a predetermined frequency band;
  Calculating means for calculating a difference between a maximum value and a minimum value of the output voltage of the filtered alternator;
  A comparison means for comparing the difference with a threshold;
  According to the comparison result of the comparison means, comprising a determination means for determining normality or abnormality of the alternator,
  The filter means holds a peak frequency of a normal alternator output voltage as a reference frequency, and filters a frequency band of 10% to 70% of the reference frequency as a passband,
  The determination means holds the difference between the maximum value and the minimum value of the output voltage of the alternator at the normal time, and the difference between the maximum value and the minimum value of the filtered output voltage of the alternator is the output voltage of the alternator at the normal time. An apparatus that determines an abnormality when the difference between the maximum value and the minimum value is 2.5 to 3.5 times or more.   In an apparatus for detecting an abnormality of an alternator,
  Input means for inputting the output voltage of the alternator;
  Filter means for filtering the output voltage of the alternator in a predetermined frequency band;
  Calculating means for calculating a difference between a maximum value and a minimum value of the output voltage of the filtered alternator;
  A comparison means for comparing the difference with a threshold;
  According to the comparison result of the comparison means, comprising a determination means for determining normality or abnormality of the alternator,
  The filter means is a low-pass filter;
  The filter means holds a peak frequency of a normal alternator output voltage as a reference frequency, and filters a frequency band of 70% or less of the reference frequency as a pass band,
  The determination means holds the difference between the maximum value and the minimum value of the output voltage of the alternator at the normal time, and the difference between the maximum value and the minimum value of the filtered output voltage of the alternator is the output voltage of the alternator at the normal time. A device that determines that the alternator is abnormal when the difference between the maximum value and the minimum value is three times or more.   In an apparatus for detecting an abnormality of an alternator,
  Input means for inputting the output voltage of the alternator;
  Filter means for filtering the output voltage of the alternator in a predetermined frequency band;
  Calculating means for calculating a difference between a maximum value and a minimum value of the output voltage of the filtered alternator;
  A comparison means for comparing the difference with a threshold;
  According to the comparison result of the comparison means, comprising a determination means for determining normality or abnormality of the alternator,
  The filter means holds a peak frequency of a normal alternator output voltage as a reference frequency, and filters a frequency band of 80% or more and 120% or less of the reference frequency as a passband,
  The determination means holds the difference between the maximum value and the minimum value of the output voltage of the alternator at the normal time, and the difference between the maximum value and the minimum value of the filtered output voltage of the alternator is the output voltage of the alternator at the normal time. A device that determines that the alternator is normal when the difference between the maximum value and the minimum value is 1 to 1.5 times.   In an apparatus for detecting an abnormality of an alternator,
  Input means for inputting the output voltage of the alternator;
  Filter means for filtering the output voltage of the alternator in a predetermined frequency band;
  Calculating means for calculating a difference between a maximum value and a minimum value of the output voltage of the filtered alternator;
  A comparison means for comparing the difference with a threshold;
  According to the comparison result of the comparison means, comprising a determination means for determining normality or abnormality of the alternator,
  The filter means holds a peak frequency of a normal alternator output voltage as a reference frequency, and filters a frequency band of 80% or more of the reference frequency as a pass band,
  The determination means holds the difference between the maximum value and the minimum value of the output voltage of the alternator at the normal time, and the difference between the maximum value and the minimum value of the filtered output voltage of the alternator is the output voltage of the alternator at the normal time. A device that determines normal when the difference between the maximum value and the minimum value is 1 to 1.5 times.   In an apparatus for detecting an abnormality of an alternator,
  Input means for inputting the output voltage of the alternator;
  Filter means for filtering the output voltage of the alternator in a predetermined frequency band;
  Calculating means for calculating a difference between a maximum value and a minimum value of the output voltage of the filtered alternator;
  A comparison means for comparing the difference with a threshold;
  According to the comparison result of the comparison means, comprising a determination means for determining normality or abnormality of the alternator,
  The filter means filters the frequency band of 100 Hz to 800 Hz as a pass band when the engine is idle.
  The determination unit is an apparatus that determines that the alternator is abnormal when a difference between a maximum value and a minimum value of the output voltage of the filtered alternator is 3 V or more.   In an apparatus for detecting an abnormality of an alternator,
  Input means for inputting the output voltage of the alternator;
  Filter means for filtering the output voltage of the alternator in a predetermined frequency band;
  Calculating means for calculating a difference between a maximum value and a minimum value of the output voltage of the filtered alternator;
  A comparison means for comparing the difference with a threshold;
  According to the comparison result of the comparison means, comprising a determination means for determining normality or abnormality of the alternator,
  The filter means is a low-pass filter;
  The filter means filters the frequency band of 800 Hz or less as a pass band when the engine is idle.
  The determination unit is an apparatus that determines that the alternator is abnormal when a difference between a maximum value and a minimum value of the output voltage of the filtered alternator is 3 V or more.   In an apparatus for detecting an abnormality of an alternator,
  Input means for inputting the output voltage of the alternator;
  Filter means for filtering the output voltage of the alternator in a predetermined frequency band;
  Calculating means for calculating a difference between a maximum value and a minimum value of the output voltage of the filtered alternator;
  A comparison means for comparing the difference with a threshold;
  According to the comparison result of the comparison means, comprising a determination means for determining normality or abnormality of the alternator,
  The filter means filters a frequency band of 1.0 KHz or more and 1.4 KHz or less as a pass band when the engine is idle.
  The determination means is a device that determines that the alternator is normal when the difference between the maximum value and the minimum value of the filtered output voltage of the alternator is 2 V or less.   In an apparatus for detecting an abnormality of an alternator,
  Input means for inputting the output voltage of the alternator;
  Filter means for filtering the output voltage of the alternator in a predetermined frequency band;
  Calculating means for calculating a difference between a maximum value and a minimum value of the output voltage of the filtered alternator;
  A comparison means for comparing the difference with a threshold;
  According to the comparison result of the comparison means, comprising a determination means for determining normality or abnormality of the alternator,
  The filter means is a high-pass filter;
  The filter means filters a frequency band of 1.0 KHz or higher when the engine is idle as a pass band,
  The determination unit is a device that determines that the alternator is normal when a difference between a maximum value and a minimum value of the filtered output voltage of the alternator is 2 V or less.   The apparatus of claim 1.
  The filter means dynamically multiplies the reference frequency by (current engine speed / specific engine speed) times from the current engine speed and a peak frequency at a specific engine speed previously held as a reference frequency. Device to correct.   The apparatus of claim 3.
  The determination means is an apparatus for determining an abnormality sign of the alternator when a difference between a filtered peak frequency of the output voltage of the alternator and a peak frequency of the output voltage of the alternator in a normal state is equal to or greater than a predetermined value.   The apparatus of claim 10.
  The determination means is an apparatus for determining an abnormality sign of the alternator when a difference between a peak frequency of the filtered output voltage of the alternator and a peak frequency of the output voltage of the alternator at a normal time is 100 Hz or more. The apparatus of claim 10.
The determination means periodically stores the deviation between the filtered peak frequency of the output voltage of the alternator and the peak frequency of the output voltage of the alternator at normal time, and the deviation stored for a certain period of time has steadily increased. In this case, the apparatus determines that the alternator is abnormal.

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