JP2016093083A - Fan motor control device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fan motor control device for a vehicle capable of preventing an influence of an electromagnetic noise with a low load and at a low cost.SOLUTION: An air conditioner ECU 78 outputs a signal including a command signal regarding a rotational speed of a motor 52 and a confirmation signal generated when a voltage of a battery 80 is stabilized within a predetermined range. A confirmation signal determination unit 88 detects an input of the confirmation signal from the signal inputted from the air conditioner ECU 78. A command rotational number holding unit 92 adopts a command rotational speed calculated from the command signal immediately preceding the input of the confirmation signal when the confirmation signal determination unit 88 has detected the input of the confirmation signal. A PI control unit 66 and a voltage correction unit 68 calculate a voltage to be applied to the motor 52 on the basis of the adopted command rotational speed.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a vehicle fan motor control device.

  A control device for a fan motor (hereinafter abbreviated as “motor”) used for blowing air from a vehicle air conditioner is a rotation command signal (SI signal) received from an air conditioner ECU (Electronic Control Unit) and a motor detected by a hall element. The rotation of the motor is controlled based on the rotation speed. Specifically, the vehicle fan motor control device controls the rotational speed of the motor using PI control that eliminates the deviation between the SI signal, which is a rotational speed command value, and the rotational speed of the motor detected by a Hall element or the like. doing.

  In order for the vehicle fan motor control device to perform appropriate control, it is required that the vehicle fan motor control device is not affected by electromagnetic noise generated from the engine or other equipment. It is often covered with a case made of a material that can shield. However, although the vehicle fan motor control device can be protected from electromagnetic noise by being housed in the case, electromagnetic noise may enter from the wire harness connecting the air conditioner ECU and the vehicle fan motor control device.

  6A and 6B are schematic diagrams showing an example of an SI signal input to the control device. FIG. 6A shows a case where there is no influence of electromagnetic noise, and FIG. 6B shows a case where there is an influence of electromagnetic noise. Yes. As shown in FIG. 6A, when the command rotational speed is constant at 1000 rpm and there is no influence of electromagnetic noise, the SI signal is a motor control device with a duty ratio corresponding to the command rotational speed of 1000 rpm. Is input. However, when there is an influence of electromagnetic noise as shown in FIG. 6B, the SI signal is disturbed by the electromagnetic noise, and what should originally be a duty ratio corresponding to the indicated rotational speed of 1000 rpm is 500 rpm. The duty ratio corresponds to. As a result, there has been a problem that the rotational speed of the motor does not follow the command value.

  By applying an electromagnetic shield such as a metal foil or a metal net to the wire harness, the influence of electromagnetic noise can be prevented. However, there is a problem that the manufacturing cost of the product increases due to the addition of the electromagnetic shield to the wire harness.

  Patent Document 1 discloses an invention of an actuator control system that detects a command value error by performing a parity check and a sum check of a command value packet received by a control device.

JP 2005-263195 A

  However, the actuator control system described in Patent Document 1 has a problem in that it is difficult to smoothly control the rotation speed of the motor because a load is applied to the control device for signal error check processing.

  The present invention has been made in view of the above, and an object of the present invention is to provide a vehicle fan motor control device capable of suppressing the control load and preventing the influence of electromagnetic noise at low cost.

  In order to solve the above-mentioned problem, the vehicle fan motor control device according to claim 1 obtains a rotation command value based on a command signal of the rotation speed of the fan motor, and is generated when the power supply voltage is within a predetermined range. A holding unit that updates the held rotation command value to the rotation command value obtained from the command signal immediately before the decision signal is input, and holds the updated rotation command value, A rotation speed control unit that controls the rotation speed of the fan motor using a rotation command value held in the holding unit.

  The vehicle fan motor control device uses a rotation command value obtained immediately before the confirmation signal is input when the confirmation signal generated when the power supply voltage is within a predetermined range is input to the holding unit. To control the rotation speed of the motor.

  Since the confirmation signal is generated when the power supply voltage is stable, it is considered that the power supply voltage is not affected by electromagnetic noise or the like when the confirmation signal is generated. Therefore, when a deterministic signal is generated, it is considered that the influence of electromagnetic noise does not reach the command signal, so if the rotation command value obtained from the command signal is used immediately before the definite signal, the influence of electromagnetic noise The rotation of the motor can be controlled without receiving it.

  The rotation speed control unit prevents the influence of electromagnetic noise by a light load process for controlling the rotation speed of the motor using the rotation command value obtained immediately before the confirmation signal is input. In such processing, an electromagnetic shield for preventing electromagnetic noise is not required for the wire harness or the like, so that the control load can be suppressed and the influence of electromagnetic noise can be prevented at low cost.

  The vehicle fan motor control device according to claim 2 is the vehicle fan motor control device according to claim 1, wherein the command signal is a pulse signal having a duty ratio corresponding to the rotation command value, and the holding unit. Obtains a rotation command value from the duty ratio of the pulse signal, and discards a rotation command value other than the rotation command value obtained immediately before the confirmation signal is input.

  According to this vehicle fan motor control device, it is possible to prevent the influence of electromagnetic noise even in a low-cost configuration with a limited storage capacity by discarding rotation command values other than rotation command values used for motor rotation control. .

  The vehicle fan motor control device according to claim 3 is the vehicle fan motor control device according to claim 1 or 2, wherein the confirmation signal is a signal having a frequency lower than a frequency on a low frequency side of the command signal.

  According to this vehicle fan motor control device, since the deterministic signal can be detected by a light load process for identifying the deterministic signal and the command signal according to the difference in frequency, even in a low-cost configuration with low arithmetic processing capability, The effect can be prevented.

  The vehicle fan motor control device according to claim 4 is the vehicle fan motor control device according to any one of claims 1 to 3, wherein the determination signal is inserted into the command signal and transmitted.

  According to this vehicle fan motor control device, the determination signal and the command signal can be easily identified based on the difference in frequency because they are a series of signals in which the determination signal is inserted into the command signal.

It is the schematic which shows the structure of the motor unit using the fan motor control apparatus for vehicles which concerns on embodiment of this invention. It is a figure which shows the outline of the fan motor control apparatus for vehicles which concerns on embodiment of this invention. BRIEF DESCRIPTION OF THE DRAWINGS Schematic which showed an example of the signal input from air-conditioner ECU to the fan motor control apparatus for vehicles in embodiment of this invention, (A) is a case where there is no influence of electromagnetic noise, (B) is electromagnetic noise. Each case is shown. It is a flowchart which shows an example of control of the rotational speed of the motor in the fan motor control apparatus for vehicles in embodiment of this invention. It is the flowchart which showed an example of the motor start sequence of the fan motor control apparatus for vehicles in embodiment of this invention. It is the schematic which showed an example of SI signal input into a control apparatus, (A) has shown the case where there is no influence of electromagnetic noise, (B) has each shown the case where there is an influence of electromagnetic noise.

  FIG. 1 is a schematic diagram showing a configuration of a motor unit 10 using a vehicle fan motor control device 20 according to the present embodiment. The motor unit 10 according to the present embodiment in FIG. 1 is a so-called fan motor unit used as an example for blowing air from a vehicle air conditioner.

  The motor unit 10 according to the present embodiment relates to a three-phase motor having an outer rotor structure in which a rotor 12 is provided outside a stator 14. The stator 14 is an electromagnet in which a lead wire is wound around a core member, and constitutes three phases of a U phase, a V phase, and a W phase.

  Each of the U-phase, V-phase, and W-phase of the stator 14 generates a so-called rotating magnetic field by switching the polarity of the magnetic field generated by the electromagnet under the control of the vehicle fan motor control device 20 described later.

  A rotor magnet is provided inside the rotor 12 (not shown), and the rotor magnet rotates the rotor 12 by responding to the rotating magnetic field generated by the stator 14.

  The rotor 12 is provided with a shaft 16 and rotates integrally with the rotor 12. Although not shown in FIG. 1, in the present embodiment, the shaft 16 is provided with a multi-blade fan such as a so-called sirocco fan, and the multi-blade fan rotates together with the shaft 16, thereby blowing air in the vehicle air conditioner. It becomes possible.

  The stator 14 is attached to the vehicle fan motor control device 20 via the upper case 18. The vehicle fan motor control device 20 includes a substrate 22 of the vehicle fan motor control device 20 and a heat sink 24 that dissipates heat generated from elements on the substrate 22.

  A lower case 28 is attached to the motor unit 10 including the rotor 12, the stator 14, and the vehicle fan motor control device 20.

  FIG. 2 is a diagram schematically illustrating the vehicle fan motor control device 20 according to the present embodiment. The inverter circuit 40 shown in FIG. 2 switches the electric power supplied to the coil of the stator 14 of the motor 52 by FET (Field Effect Transistor). For example, the inverter FETs 44A and 44D switch the power supplied to the U-phase coil 14U, the inverter FETs 44B and 44E switch to the V-phase coil 14V, and the inverter FETs 44C and 44F switch the power supplied to the W-phase coil 14W.

  The drains of the inverters FETs 44A, 44B, and 44C are connected to the positive electrode of the on-vehicle battery 80 via the choke coil 82. The sources of the inverters FET 44D, 44E, and 44F are connected to the negative electrode of the battery 80.

  In addition to the inverter circuit 40 described above, the U-phase comparator 54U, the V-phase comparator 54V, the W-phase comparator 54W, the standby circuit 60, and the main power supply are energized on the board of the vehicle fan motor control device 20 of the present embodiment. A unit 62, an energization control drive waveform determination unit 64, a PI control unit 66, a voltage correction unit 68, an FET driver 70, and the like are mounted.

  A choke coil 82 and smoothing capacitors 84A and 84B are mounted on the substrate of the vehicle fan motor control device 20 of the present embodiment, and an air conditioner ECU (Electronic Control Unit) 78, which is a higher-level control device, A battery 80 is connected. The choke coil 82 and the smoothing capacitors 84A and 84B together with the battery 80 constitute a substantially DC power source. The air conditioner ECU 78 is an electronic control unit for the vehicle air conditioner. When the user turns on the air conditioner by the air conditioner ECU 78, the motor 52 is operated under the control of the vehicle fan motor control device 20. When the user adjusts the air volume of the vehicle air conditioner, a signal for instructing the rotational speed of the motor 52 (rotor 12) is input via the air conditioner ECU 78.

  In the present embodiment, the U-phase Hall element 12U, the V-phase Hall element 12V, and the W-phase Hall element 12W detect the magnetic field of the sensor magnet provided coaxially with the shaft 16. The position and rotational speed of the rotor 12 required for determining the drive waveform of the voltage applied to the U-phase Hall element 12U in the coil 14U, the V-phase Hall element 12V in the coil 14V, and the W-phase Hall element 12W in the coil 14W, respectively. Is detected.

  The U-phase comparator 54U converts the analog output of the U-phase Hall element 12U, the V-phase comparator 54V converts the analog output of the V-phase Hall element 12V, and the W-phase comparator 54W converts the analog output of the W-phase Hall element 12W into digital signals. It is a device to do. The actual rotational speed calculation unit 56 calculates the actual rotational speed of the rotor 12 based on the digital signals output from the U-phase comparator 54U, the V-phase comparator 54V, and the W-phase comparator 54W.

  The signal output from the air conditioner ECU 78 is input to the command rotation number calculation / holding unit 86 and the confirmation signal determination unit 88. The signals output from the air conditioner ECU 78 include an SI signal that is a rotational speed command value and a determination signal that is generated and output when the voltage of the battery 80 is stable within a predetermined range. The predetermined range of the voltage of the battery 80 is, for example, ± 5% around 12V, and 11.4 to 12.6V in terms of voltage value.

  The voltage of the battery 80 is determined by cranking that activates a cell motor (not shown) to start the engine, or when the alternator (not shown) charges the battery 80 and the alternator and the battery 80 are disconnected. It fluctuates due to the load dump that occurs when Furthermore, the voltage of the battery 80 may fluctuate due to the influence of electromagnetic noise. Since the fluctuation of the voltage of the battery 80 also affects the control of the rotation speed of the motor 52, in this embodiment, the air conditioner ECU 78 outputs a confirmation signal when the voltage of the battery 80 is stable within a predetermined range. The vehicle fan motor control device 20 controls the rotational speed of the motor 52 at the timing when the confirmation signal is output.

  The command rotation number calculation / holding unit 86 calculates a command rotation speed according to the SI signal included in the signal input from the air conditioner ECU 78. Further, when the signal input from the air conditioner ECU has a predetermined frequency different from the SI signal, the determination signal determination unit 88 determines that the input signal is a determination signal.

  In the present embodiment, for example, the SI signal is a pulse signal having a frequency of about 500 Hz and a duty ratio that changes according to a command value for the rotational speed. The confirmation signal is, for example, a pulse signal having a frequency of 20 Hz and a duty ratio of 50%. The confirmation signal determination unit 88 determines that the input signal is a determination signal when the frequency of the signal input from the air conditioner ECU 78 is 20 Hz. The determination signal determination unit 88 determines that the input signal is a determination signal when the frequency of the input signal is 20 Hz and the duty ratio of the input signal is a predetermined value of 50%. Good.

  As described above, the deterministic signal is a signal having a frequency lower than the frequency on the low frequency side of the SI signal, but if it has a predetermined frequency different from the SI signal, for example, a high frequency of the SI signal such as several kHz. It may be a signal having a higher frequency than the side.

  The command rotational speed calculation / holding unit 86 outputs the calculated command rotational speed information, and the determination signal determination unit 88 outputs the determination result that the signal input from the air conditioner ECU 78 is the determination signal, to the AND gate 90, respectively. To do. The AND gate 90 holds the command rotational speed information and the timing information at which the confirmation signal is output when the command rotational speed information is retained and the confirmation signal is input. Output to.

  In order to employ the command rotation speed holding unit 92 to control the rotation speed of the motor 52, the command rotation speed obtained based on the SI signal immediately before the confirmation signal is input among the information on the held command rotation speed. The information on the command rotation speed that has been held is updated. In addition, the command rotational speed holding unit 92 discards information on other command rotational speeds that have been held so far. By discarding information that is not subjected to rotation control, the influence of electromagnetic noise can be prevented even in a low-cost configuration with a limited storage capacity.

  FIG. 3 is a schematic diagram illustrating an example of a signal input from the air conditioner ECU 78 to the vehicle fan motor control device 20 according to the present embodiment. FIG. 3A illustrates a case where there is no influence of electromagnetic noise, and FIG. Each case shows the influence of electromagnetic noise. As shown in FIGS. 3A and 3B, the signal input from the air conditioner ECU 78 to the vehicle fan motor control device 20 is a rectangular wave including the SI signal and the confirmation signal 102.

  In FIG. 3A, the frequency of the SI signal is approximately 500 Hz, and the definite signal 102 has a frequency of 20 Hz and a duty ratio of 50%. As shown in FIG. 3A, the deterministic signal 102 is inserted into the SI signal and transmitted. The vehicle fan motor control device 20 identifies a signal having a predetermined frequency and a predetermined duty ratio different from the SI signal from the confirmation signal 102, and when the confirmation signal 102 is input, immediately before the confirmation signal 102 is input. The rotation speed of the motor 52 is controlled by using the command value indicated by the SI signal.

  The frequency at which the confirmation signal 102 is output is lower than the frequency at which the SI signal is output. Therefore, the frequency of controlling the rotational speed is lower than when the rotational speed of the motor 52 is controlled every time the SI signal is output, but the motor 52 used in the vehicle air conditioner As long as there is no change in the air volume or temperature setting, in principle, it rotates at a constant speed, so there is no practical problem.

  As shown in FIG. 3B, in this embodiment, the SI signal input immediately before the confirmation signal 102 is input is regarded as having no influence of electromagnetic noise, and the confirmation signal 102 is input. The command value indicated by the immediately preceding SI signal is adopted to control the rotation speed of the motor 52.

  As shown in FIGS. 3A and 3B, the control of the rotation speed of the motor 52 is basically the same regardless of the presence or absence of electromagnetic noise. As will be described later with reference to FIG. 4, in the present embodiment, the rotational speed of the motor 52 can be controlled with simple logic regardless of the presence or absence of the influence of electromagnetic noise.

  The command rotational speed holding unit 92 in FIG. 2 outputs the command rotational speed obtained immediately before the confirmation signal is input to the PI control unit 66. In the present embodiment, the command rotation speed is approximately 1000 to 5000 rpm.

  The PI control unit 66 uses a coil of the stator 14 to change the actual rotation speed to the command rotation speed from the command rotation speed output by the command rotation speed holding unit 92 and the actual rotation speed calculated by the actual rotation speed calculation unit 56. The voltage applied to is calculated by so-called PI control. The PI control unit 66 includes a deviation proportional unit 66P that calculates a voltage at the target rotational speed based on a proportional relationship between a deviation between the target rotational speed and the actual rotational speed and a deviation between the voltage at the target rotational speed and the voltage at the actual rotational speed. Including. Further, the PI control unit 66 includes a deviation integration unit 66I that eliminates the residual deviation by deviation integration when the residual deviation is generated only by the proportional relationship. The voltage correction unit 68 corrects the voltage applied to the coil of the stator 14 based on the calculation result by the PI control unit 66.

  The standby circuit 60 is a circuit that controls power supply from the battery 80 to each unit. Further, the main power supply energization unit 62 turns on the power to the vehicle fan motor control device 20 according to the control of the standby circuit 60. The main power supply energization unit 62 turns on the overvoltage determination unit 72 and determines whether or not the voltage of the power supplied from the battery 80 is in an overvoltage state exceeding a predetermined upper limit. The predetermined upper limit of the voltage is, for example, 13V.

  The overvoltage determination unit 72 outputs a true determination signal 74A to the voltage value switching unit 76 when it is determined that the overvoltage state is determined, and a false determination signal 74B when it is determined that the overvoltage state is not determined. The voltage value switching unit 76 outputs the voltage value corrected by the voltage correction unit 68 to the FET driver 70 when the false determination signal 74B is input, and the overvoltage state when the true determination signal 74A is input. Outputs a voltage value to eliminate the problem. There are various possible voltage values for eliminating the overvoltage state. For example, the voltage value forcibly controls the rotational speed of the motor 52 to a low speed of about 500 rpm.

  When power is supplied via the standby circuit 60 and the main power supply energization unit 62, the energization control drive waveform determination unit 64 determines the drive waveform of the voltage applied to the coil of the stator 14.

  The FET driver 70 generates a PWM signal for controlling the switching of the inverter circuit 40 based on the drive waveform determined by the energization control drive waveform determination unit 64 and the voltage value corrected by the voltage correction unit 68 to generate an inverter. Output to the circuit 40.

  Further, a current detecting shunt resistor 94 is provided between the source of each of the inverters FETs 44D, 44E and 44F and the battery 80. The shunt resistor 94 is a resistor having a resistance value of about 0.2 mΩ to several Ω, and an amplifier (not shown) that amplifies the potential difference between both ends of the shunt resistor 94 and outputs a voltage value proportional to the current of the shunt resistor 94 as a signal. Connected). When the signal output from the amplifier is in an overcurrent state exceeding a predetermined threshold, control is performed to reduce the rotational speed of the motor 52 below the command value indicated by the SI signal.

  FIG. 4 is a flowchart showing an example of control of the rotation speed of the motor 52 in the vehicle fan motor control device 20 according to the present embodiment. When the switch of the vehicle air conditioner is turned on, a motor start sequence described later is executed in step 400.

  In step 402, the command rotational speed is calculated from the SI signal input from the air conditioner ECU 78, and in step 404, the determination signal determination unit 88 determines whether a determination signal is input from the air conditioner ECU 78. If the confirmation signal is not input, the process of calculating the command rotation speed from the SI signal input from the air conditioner ECU 78 is continued until the determination signal is input.

  If it is determined in step 404 that a confirmation signal has been input, the command rotational speed calculated immediately before the confirmation signal is input in step 406 is adopted as the command value, and is retained by the command rotational speed retaining unit 92. The command rotational speed calculated from the SI signal input at a timing other than immediately before the command rotational speed and the confirmation signal input when the final determination signal is input is updated. In step 408, the rotational speed of the motor 52 is controlled based on the employed command rotational speed.

  As described above, every time a confirmation signal is input, only the rotation command value calculated by the SI signal input immediately before the input of the determination signal is held in the rotation speed calculation / holding unit 86 and calculated at other times. The rotation command value is discarded, and the rotation of the motor 52 is controlled by the held rotation command value.

  That is, since the rotation command value calculated from the SI signal on which electromagnetic noise or the like is superimposed is discarded and is not used, the rotation of the fan motor can be controlled without being affected by the electromagnetic noise or the like.

  In step 410, it is determined whether or not the vehicle air conditioner switch has been turned off. If the determination is affirmative, the process ends. If the determination is negative, the procedure returns to step 402 to rotate the motor 52. Continue speed control.

  FIG. 5 is a flowchart showing an example of a motor start sequence of the vehicle fan motor control device 20 in the present embodiment. The flowchart shown in FIG. 5 is processing in step 400 of FIG. In step 500, the position of the rotor 12 is detected based on signals output from the U-phase hall element 12U, the V-phase hall element 12V, and the W-phase hall element 12W.

  In step 502, a sine wave voltage having a large period is applied to the coil of the stator 14 to rotate the rotor 12, and in step 504, the voltage value of the sine wave voltage applied to the coil of the stator 14 is gradually increased to increase the rotor. The rotational speed of 12 is gradually increased.

  In step 506, the cycle of the sine wave voltage is controlled according to the position of the rotating rotor 12, and in step 508, it is determined whether or not the rotational speed of the rotor 12 has reached a predetermined rotational speed. The predetermined rotation speed is 1000 rpm as an example. If the determination in step 508 is affirmative, the process is returned. If the determination is negative in step 508, the procedure returns to step 506, and the position of the rotor 12 is changed until the rotational speed of the rotor 12 reaches a predetermined rotational speed. The control of the period of the sine wave voltage is continued according to

  As described above, in the present embodiment, the air conditioner ECU 78 outputs a confirmation signal when the voltage of the battery 80 is stabilized, and the vehicle fan motor control device 20 performs the operation when the confirmation signal is input from the air conditioner ECU 78. The rotation speed of the motor 52 is controlled by adopting the SI signal input immediately before the confirmation signal is input. When the confirmation signal is output, it is considered that the influence of electromagnetic noise or the like does not occur in the voltage of the battery that is the power source. Therefore, the SI signal immediately before the confirmation signal is input to the vehicle fan motor control device 20 Is not considered to be affected by electromagnetic noise. Therefore, if the SI signal immediately before the confirmation signal is input to the vehicle fan motor control device 20 is used, the rotation speed of the motor 52 can be controlled while preventing the influence of electromagnetic noise.

  Further, in the present embodiment, since it is not necessary to provide an electromagnetic shield for blocking electromagnetic noise on the wire harness, the cost is low, and as described above, the rotational speed of the motor 52 is controlled by waiting for the input of a confirmation signal. Since it is based on the simple control of performing, there is an effect that the control load is light.

DESCRIPTION OF SYMBOLS 10 ... Motor unit, 12 ... Rotor, 12U ... U phase Hall element, 12V ... V phase Hall element, 12W ... W phase Hall element, 14 ... Stator, 14U, 14V, 14W ... Coil, 16 ... Shaft, 18 ... Upper case 20 ... Vehicle fan motor control device, 22 ... substrate, 24 ... heat sink, 28 ... lower case, 40 ... inverter circuit, 44A, 44B, 44C, 44D, 44E, 44F ... inverter FET, 52 ... motor, 54U ... U Phase comparator, 54V ... V phase comparator, 54W ... W phase comparator, 56 ... Actual rotation speed calculation unit, 60 ... Standby circuit, 62 ... Main power supply energization unit, 64 ... Energization control drive waveform determination unit, 66 ... PI control unit, 66I ... Deviation integration unit, 66P ... Deviation proportional unit, 68 ... Voltage correction unit, 70 ... FET driver, 72 ... Overvoltage determination unit, 4A ... True determination signal, 74B ... False determination signal, 76 ... Voltage value switching unit, 80 ... Battery, 82 ... Choke coil, 84A, 84B ... Smoothing capacitor, 86 ... Command rotational speed calculation / holding unit, 88 ... Determination signal determination , 90 ... AND gate, 92 ... Command rotational speed holding part, 94 ... Shunt resistor, 102 ... Confirmation signal

Claims (4)

The rotation command value is obtained based on the rotation speed command signal of the fan motor, and when the determination signal generated when the power supply voltage is within the predetermined range is input, the held rotation command value is input to the determination signal. Updating the rotation command value obtained from the command signal immediately before being held, and holding the updated rotation command value;
A rotation speed control unit that controls the rotation speed of the fan motor using a rotation command value held in the holding unit;
A vehicle fan motor control apparatus including: The command signal is a pulse signal having a duty ratio according to the rotation command value,
2. The fan motor control for a vehicle according to claim 1, wherein the holding unit obtains a rotation command value from a duty ratio of the pulse signal and discards a rotation command value other than the rotation command value obtained immediately before the confirmation signal is input. apparatus.   The vehicle fan motor control device according to claim 1 or 2, wherein the confirmation signal is a signal having a frequency lower than a frequency on a low frequency side of the command signal.   The vehicle fan motor control device according to claim 1, wherein the confirmation signal is inserted into the command signal and transmitted.

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