JP2012220198A - On-vehicle radar device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an on-vehicle radar device that can detect a current consumption abnormality in an inner circuit of a chopper type power source circuit or an abnormality in power conversion efficiency, without using a current detection resistor.SOLUTION: The on-vehicle radar device includes an input voltage acquisition circuit 13 for acquiring an input voltage of the chopper type power source circuit, a duty ratio voltage conversion circuit 9 for converting a duty ratio of the chopper type power source circuit to a voltage, and a correlation table between the input voltage of the chopper type power source circuit and the duty ratio conversion voltage during normal periods, and detects the current consumption abnormality in an inner circuit of the chopper type power source circuit or the abnormality in the power conversion efficiency by comparing the duty ratio conversion voltage acquired by duty ratio voltage conversion circuit 9 with the correlation table on the basis of the input voltage acquired by the input voltage acquisition circuit 13.

Description

  The present invention relates to a vehicle-mounted radar device that transmits and receives a radio wave (radio wave) to calculate a distance, speed, angle, etc. from an own vehicle to an obstacle (detected object) within a predetermined range, and particularly for the vehicle-mounted radar device. The present invention relates to a chopper type power supply circuit that is used in a radar apparatus and performs voltage conversion from a battery voltage supplied from a vehicle to an internal circuit voltage.

  In an on-vehicle radar device, self-heating may be a problem because of a relatively large current consumption per device capacity and a sealed structure for waterproofing. The power supplied from the vehicle is generally a 12V or 24V battery voltage, and the internal circuit power supply voltage (internal circuit voltage) is generally 5 V or less. Therefore, a dropper type power supply circuit using a transistor is used. However, since the loss of the power supply circuit becomes too large, a chopper type power supply circuit is often used.

  As a means for detecting abnormality of the power supply circuit, there is a method of monitoring the output voltage with an AD converter mounted on a microcomputer, irrespective of the chopper type power supply circuit or the dropper type power supply circuit, but the power supply circuit (secondary side) It should have been designed with a margin for the load current (internal circuit current consumption), and even if there is an increase or decrease in load current due to internal circuit anomalies (deterioration or failure of parts), it should be within the design margin range. For example, no change appears in the monitor voltage, and it is difficult to detect the abnormality (change). In addition, even if there is an increase in primary current (input current) due to power conversion efficiency reduction due to component degradation of the chopper type power supply circuit, it cannot be detected only by monitoring the output voltage of the chopper type power supply circuit.

  In chopper type power supply circuits, it is known that the ripple current applied to the primary side capacitor (input side capacitor) increases in proportion to the load current, and the increase in ripple current has a significant effect on the capacitor life. At the time of design, an input capacitor with a margin should be selected for the ripple current calculated from load current, primary voltage (input voltage), secondary voltage (output voltage), and power conversion efficiency. However, if the ripple current increases due to a decrease in power conversion efficiency of the chopper type power supply circuit, etc., it also shortens the capacitor life assumed at the beginning of the design, so it is important to detect changes in the internal circuit current consumption. .

  As a conventional technique, a method of detecting a power supply system abnormality by monitoring an output voltage of a power supply circuit or mounting a current detection resistor on a power supply line and monitoring a potential difference (current × resistance) is used. A similar method is disclosed in Patent Document 1, for example.

JP-A-11-108969

  In the prior art, it is possible to detect the current consumption by mounting a current detection resistor on the power supply line supplied from the vehicle. However, since the current detection resistor causes a voltage drop, There is a problem that the margin with respect to the lower limit value is cut, and in addition, wasteful power consumption (heat generation) occurs. Therefore, a simple fault detection method that replaces the current detection resistor is desired for detection of increase / decrease in internal circuit current consumption due to circuit failure and deterioration of in-vehicle radar equipment, and detection of abnormal increase in ripple current (impedance increase) in the input side capacitor. .

  The present invention has been made to solve the above-described problems. In a chopper type power supply circuit in which a switching control cycle for performing voltage conversion from a battery voltage to an internal circuit voltage in an in-vehicle radar device is constant, A failure / performance degradation due to abnormal circuit current consumption or abnormal power conversion efficiency, and preferably a failure / performance degradation due to abnormal impedance of the input side capacitor of the chopper type power supply circuit, is caused by current detection resistors that generate heat and voltage. It is an object of the present invention to provide a highly reliable on-vehicle radar device that is detected using a simple circuit.

  A vehicle-mounted radar device according to the present invention determines a transmission antenna and a transmission circuit that transmit radio waves to a detected object, a reception antenna and a reception circuit that receives radio waves reflected by the detected object, and a frequency of the transmission radio waves. A voltage controlled oscillator VCO; a DA converter that controls the voltage controlled oscillator VCO; an AD converter that quantizes a frequency difference between a received radio wave received by the receiving circuit and an output of the voltage controlled oscillator VCO; Arithmetic means for performing radar signal processing for calculating the distance, speed, and angle to the detected object based on the output of the converter, and a voltage conversion circuit for converting the supply voltage from the vehicle into a predetermined internal circuit voltage The voltage conversion circuit is a chopper type power supply circuit comprising a chopper type power supply circuit having a constant switching control cycle as an input side power supply circuit. The input voltage acquisition circuit for acquiring the input voltage of the source circuit, the duty ratio voltage conversion circuit for converting the duty ratio of the chopper type power supply circuit into a voltage, and the normality of the input voltage and the duty ratio conversion voltage of the chopper type power supply circuit Correlation table A, the duty ratio conversion voltage obtained by the duty ratio voltage conversion circuit is compared with the correlation table A based on the input voltage obtained by the input voltage acquisition circuit, and the chopper type This is to detect a power supply system abnormality such as an internal circuit current consumption abnormality or power conversion efficiency abnormality of the power supply circuit.

  The on-vehicle radar device according to the present invention further includes a ripple voltage amplitude extracting circuit that extracts a ripple voltage amplitude applied to an input side capacitor of the chopper type power circuit, and an input voltage and a ripple voltage amplitude of the chopper type power circuit. And a normal correlation table B, the ripple voltage amplitude obtained by the ripple voltage amplitude extraction circuit is compared with the correlation table B based on the input voltage obtained by the input voltage acquisition circuit, and A power supply system abnormality, such as an impedance abnormality of an input side capacitor of a chopper type power supply circuit, is detected.

According to the on-vehicle radar device of the present invention, it is possible to detect an internal circuit current consumption abnormality or power conversion efficiency abnormality of the chopper type power supply circuit without using a current detection resistor. Therefore, it is possible to obtain a highly reliable on-vehicle radar device that enables power supply system monitoring.
Further, according to the on-vehicle radar device of the present invention, in addition to the above, an impedance abnormality of the input side capacitor of the chopper type power supply circuit can be detected without using a current detection resistor. It is possible to obtain a highly reliable on-vehicle radar device that enables power supply system monitoring without being affected.

It is a block diagram which shows the structure of the vehicle-mounted radar apparatus to which this invention is applied. It is a block diagram which shows the structure of the vehicle-mounted radar apparatus in Embodiment 1 of this invention. It is a figure which shows the relationship between the load current of a chopper type power supply circuit, efficiency, and a duty ratio. 3 is a diagram illustrating a duty ratio voltage conversion circuit of the chopper type power supply circuit according to Embodiment 1. FIG. 3 is a diagram illustrating a ripple voltage amplitude extraction circuit of an input side capacitor of the chopper type power supply circuit according to Embodiment 1. FIG. FIG. 6 is a diagram for explaining a determination procedure for abnormality of the chopper type power supply circuit according to the first embodiment. FIG. 10 is a diagram for explaining an abnormality determination procedure for a chopper type power supply circuit according to a third embodiment.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing the configuration of an on-vehicle radar device to which the present invention is applied. In the figure, an on-vehicle radar device 1 includes a radio wave transmission / reception circuit 3, a microcomputer (calculation means) 4, a power supply circuit 2, and a communication interface 5. The radio wave transmission / reception circuit 3 includes a transmission antenna 3a, a reception antenna 3b (the antenna 3a and the antenna 3b may be shared by providing a switch between the antenna and the transmission / reception circuit), a transmission circuit 3d, and a reception circuit 3e. The transmitting antenna 3a and the transmitting circuit 3d transmit radio waves (radio wave beams) to the detected object, and the receiving antenna 3b and the receiving circuit 3e receive the radio waves reflected by the detected object.

  The radio wave transmission / reception circuit 3 further includes a VCO (Voltage Controlled Oscillator) 3f that determines the frequency of the transmission radio wave, and a DAC (Digital to Analog Converter: DA converter) 3g that controls the VCO 3f. The DAC 3g generates a frequency modulation control signal for controlling the frequency modulation of the transmission radio wave transmitted by the transmission circuit 3d, and controls the voltage controlled oscillator VCO3f. The radio wave transmission / reception circuit 3 further includes an ADC (Analog-to Digital Converter) 3h that quantizes the frequency difference between the reception radio wave received by the reception circuit 3e and the VCO 3f output.

  The microcomputer (arithmetic means) 4 (a microcomputer is mentioned as an example, but a dedicated circuit such as an FPGA (Field-Programmable Gate Array) or a DSP (Digital Signal Processor) may be provided separately) Based on the transmission signal transmitted by the transmission circuit 3d and the reception signal received by the reception circuit 3e), radar signal processing for calculating the distance, speed, and angle to the detected object is performed. The power supply circuit (voltage conversion circuit) 2 converts a supply voltage (for example, 12V) from the vehicle battery 15 into a predetermined internal circuit voltage (internal circuit power supply voltage), for example, 5V.

  The power supply circuit 2 forms a filter circuit with the capacitor C1 and the inductor L1, and forms a chopper type power supply circuit with the input side capacitor C2, transistor Q1, diode D1, inductor L2, capacitor C3, resistors R1 and R2, and the control IC8. Yes. The control IC 8 controls the internal circuit voltage of the chopper type power supply circuit to be constant. The input voltage of the chopper type power supply circuit (that is, the voltage of the input side capacitor C2) is input to the microcomputer 4 by the input voltage acquisition circuit 13. The output voltage of the chopper type power supply circuit (that is, the voltage for the internal circuit) is input to the microcomputer 4 by the output voltage acquisition circuit 14.

  In general, the on-vehicle radar device 1 may have a problem of self-heating due to a large current consumption of an internal circuit for a small capacity and a sealed structure for waterproofing. Therefore, in many cases, the input side (primary side) power supply circuit is a chopper type power supply circuit for the purpose of suppressing the loss of the power supply circuit 2, and an inexpensive chopper type power supply circuit having a constant switching control cycle is used. Even in the present invention, the power supply circuit (voltage conversion circuit) 2 uses a chopper type power supply circuit having a constant switching control cycle as the input side power supply circuit.

  As an abnormality detection means of the power supply circuit 2, a method of monitoring the output voltage with an AD converter mounted on a microcomputer is generally used regardless of the chopper type power supply circuit or the dropper type power supply circuit. However, the chopper type power supply circuit should be designed with a margin for the load current (internal circuit current consumption), and there is an increase or decrease in internal circuit current consumption due to internal circuit abnormalities (component failure, performance degradation). Even if it is within the range of the design margin, no change appears in the monitor voltage, and it is difficult to detect the abnormality (change).

  In addition, even if there is an increase in input side current due to a decrease in power conversion efficiency due to component deterioration of the chopper type power supply circuit, there is a problem that it cannot be detected by output monitoring of the chopper type power supply circuit. An abnormality (change) in the load current can be detected by monitoring the voltage drop of the current detection resistor with the AD converter of the microcomputer 4 via the difference circuit. However, the in-vehicle radar device 1 has a useless loss (heat generation). This is not preferable because it causes a loss of the margin for the required minimum guaranteed operating voltage.

In a general chopper type power supply circuit, the relationship between the load current Io (A) and the power conversion efficiency α (%) is as shown by the solid line in FIG. It has been known. This is (on / off) duty ratio Duty (that is, Duty = Ton / T
However, when Ton is an on-period and T is a period), the on-ratio is controlled at a point with low efficiency, and the on-ratio is controlled at a point with high efficiency. Can be expressed as: Since the output voltage of the chopper type power supply circuit is kept constant at, for example, 5 V, it can be understood that the input-output voltage difference can be considered using the input voltage of the chopper type power supply circuit as a parameter. Since the output voltage Vo of the chopper type power supply circuit is monitored by the microcomputer 4, if this fluctuates, it may be determined that the power supply circuit is abnormal.

The duty ratio Duty (Duty = Ton / T) of the gate control signal of the switching element Q1 in the chopper type power supply circuit is Duty = (Vo / Vi) / α = (Ii / Io) / α
∵ When α = 1 Vi × Ii = Vo × Io
Where Vi: input voltage of chopper type power supply circuit = Q1 input voltage Vo: output voltage of chopper type power supply circuit = voltage for internal circuit Ii: input current of chopper type power supply circuit = Q1 input current Io: output of chopper type power supply circuit Current = Internal circuit current consumption (load current)
α: Power conversion efficiency in the chopper type power supply circuit (1>α> 0)
It can be expressed as.

  Here, Vo is set as a target value, and is controlled by the control IC 8 so that the output voltage Vo is stabilized regardless of the increase or decrease of the input voltage Vi and the internal circuit consumption current Io. In general, the power conversion efficiency α (%) in the chopper type power supply circuit has a characteristic depending on the load current Io (A) as shown in FIG. 3, and therefore, if Vo and Vi are constant, the load current Io Changes in the duty ratio can be observed by increasing / decreasing. Further, assuming that Vo, Vi, and Io are constant, the change in the duty ratio is considered to be a change in the power conversion efficiency α due to deterioration of the components of the chopper type power supply circuit.

  A duty ratio voltage conversion circuit 9 which will be described later with reference to FIG. 2 is provided, and a voltage obtained by monitoring the duty ratio conversion voltage thus obtained and the input / output voltages Vi and Vo (Vo is normally constant) of the chopper type power supply circuit with a microcomputer 4 is obtained. By comparing the normal duty ratio conversion voltage with a table that records the relationship between Vi and Vo (Vo is usually constant), the power conversion efficiency α of the chopper type power supply circuit decreases abnormally (changes) or the internal circuit current consumption An increase / decrease abnormality (change) in Io can be detected.

  In this way, paying attention to the relationship of FIG. 3, if the duty ratio Duty of the chopper type power supply circuit is converted to a value that can be monitored by the microcomputer 4, the power conversion efficiency α accompanying the change in the load current or the deterioration of the components of the chopper type power supply circuit The change of can be detected. In order to convert the duty ratio Duty into an analog value, a low-pass filter may be used. However, the on / off duty control signal of the chopper type power supply circuit controls the transistor Q1, and therefore the amplitude is the input voltage (chopper type power supply circuit). It depends on the voltage of the input side capacitor C2 in FIG. Since the input voltage is a battery voltage supplied from the vehicle and fluctuates, an analog value obtained by passing a low-pass filter through the on / off duty control signal takes a value depending on the fluctuation of the battery voltage. It becomes indistinguishable from the change of the off duty ratio itself.

  FIG. 2 is a block diagram showing the configuration of the in-vehicle radar device according to Embodiment 1 of the present invention. FIG. 4 is a diagram for explaining the duty ratio voltage conversion circuit of the chopper type power supply circuit according to the first embodiment. As shown in the duty ratio voltage conversion circuit 9 of FIGS. 2 and 4, voltage conversion is performed so that the amplitude of the on / off duty control signal is constant by a push-pull circuit including transistors Q9a and Q9b using a constant voltage source. Then, the low-pass filter shown in FIG. 4 (in the example, the RC primary filter using the resistor R9a and the capacitor C9a is used, but the filter configuration is not limited to this, and the filter has a sufficient filter effect on the on / off frequency. The analog value obtained in (Good) is a value representing an on / off duty ratio, that is, a duty ratio conversion voltage. By monitoring this with the microcomputer 4, it becomes possible to detect a change in load current or a change in power conversion efficiency due to component deterioration.

  In order to determine whether or not the analog value corresponding to the on / off duty ratio obtained by the duty ratio voltage conversion circuit 9, that is, whether the duty ratio conversion voltage is in the normal range, a master threshold value is required. Since the relationship between the load current and the duty ratio Duty in the chopper type power supply circuit changes depending on the input voltage Vi when the output voltage (internal circuit voltage) Vo is controlled to be constant, the in-vehicle radar device 1 is in a normal state. A correlation table using the duty ratio Duty corresponding to the load current at a certain time as an input voltage parameter is prepared in advance (stored in the microcomputer 4), and the input voltage and duty ratio conversion voltage observed each time by the microcomputer 4 Can be detected by using the correlation table to detect a change in load current (abnormal state). In addition, the determination threshold value in the comparison with the correlation table has a certain voltage width with respect to the correlation table center value, thereby preventing erroneous determination due to noise (noise on the circuit, component characteristic variation, etc.). be able to. In other words, the correlation table has a voltage width that allows noise as the duty ratio conversion voltage in the normal state with respect to the input voltage of the chopper type power supply circuit. The voltage width of the determination threshold may be determined based on noise factors, margins, and the like by the in-vehicle radar device.

In addition, a ripple current Irip (r) applied to the input side capacitor C2 of the chopper type power supply circuit
ms: effective value) is defined by the load current of the chopper type power supply circuit and the voltage difference between the input and output, and can be expressed by the following equation.

Assuming that the impedance of the capacitor C2 is constant, the ripple current Irip applied to the capacitor C2 is observed as a ripple voltage on the capacitor C2. On the contrary, when the ripple current Irip applied to the capacitor C2 is constant, the ripple voltage increases or decreases.
It can be considered as an impedance increase or decrease of 2. By providing ripple voltage amplitude extraction circuits 6 and 7 to be described later in FIG. 5, the ripple voltage amplitude (voltage average value) applied to the capacitor C2 is observed by the microcomputer 4, so that an abnormal increase in impedance due to deterioration of the capacitor C2 ( Change) can be detected.

  The input side capacitor C2 has an inherent impedance in structure, and a ripple voltage proportional to the ripple current amplitude can be observed. Due to the deterioration of the input side capacitor C2, the impedance generally increases, and the observed ripple voltage amplitude also increases. The ripple voltage amplitude can be extracted by using the positive clamp circuit 6 and the peak detection circuit 7 of FIG. The positive clamp circuit 6 and the peak detection circuit 7 constitute a ripple voltage amplitude extraction circuit for the input side capacitor of the chopper type power supply circuit.

  This will be described in detail with reference to FIG. FIG. 5 is a diagram for explaining a ripple voltage amplitude extraction circuit of the input side capacitor of the chopper type power supply circuit according to the first embodiment. The ripple voltage observed on the input-side capacitor oscillates around the primary-side voltage (12V in FIG. 5), and in order to remove this 12V offset, DC cut is performed by the capacitor C6a in FIG. The ripple voltage amplitude lower limit value is clamped at the diode D6a to GND (here, a typical clamp circuit is taken as an example, and the forward voltage of the diode D6a is assumed to be 0 V), thereby extracting only the ripple voltage. Can do.

  Next, the ripple voltage amplitude is converted into a voltage using a general peak detection circuit 7 shown in FIG. The operational amplifier OP7a here is for the purpose of impedance conversion of the output of the positive clamp circuit 6, and is an operational amplifier, for example. When the input voltage of the operational amplifier OP7a is higher than the output voltage of the diode D7a, the capacitor C7a is charged. If the output voltage of the diode D7a becomes higher than the input voltage of the operational amplifier OP7a, the operational amplifier OP7a tries to draw a current, but by blocking the current to the diode D7a, the peak voltage is held by the capacitor C7a. . The resistor R7c is a discharge resistor for the capacitor C7a for providing a filter characteristic so as not to retain local peak noise or the like.

  In order to determine whether the ripple voltage amplitude obtained by the ripple voltage amplitude extraction circuit of the input side capacitor of the chopper type power supply circuit is in a normal range, a threshold value as a master is necessary. Since the ripple voltage amplitude in the chopper type power supply circuit varies depending on the input voltage, a correlation table is prepared in advance using the input voltage as a parameter for the ripple voltage amplitude when the in-vehicle radar device 1 is in a normal state (stored in the microcomputer 4). In addition, by comparing the input voltage and the ripple voltage amplitude observed each time by the microcomputer 4 using the correlation table, it is possible to detect an impedance increase abnormality of the input side capacitor. In addition, the determination threshold in the comparison with the correlation table has a certain voltage amplitude width with respect to the correlation table center value, thereby preventing erroneous determination due to noise (noise on the circuit, component characteristic variation, etc.). can do. That is, the correlation table has a voltage amplitude width that allows noise as the ripple voltage amplitude at the normal time with respect to the input voltage of the chopper type power supply circuit. The voltage amplitude width of the determination threshold may be determined based on noise factors, margins, etc. by the in-vehicle radar device.

  The on-vehicle radar apparatus shown in FIG. 2 of the first embodiment described above uses the duty ratio voltage conversion circuit and the ripple voltage amplitude extraction circuit shown in FIGS. Make a decision. FIG. 6 is a diagram illustrating a procedure for determining an abnormal state of the chopper type power supply circuit according to the first embodiment. First, the duty ratio conversion voltage is monitored (step S1), and compared with a correlation table prepared in advance based on the input voltage at that time. If the monitored duty ratio conversion voltage is outside the threshold range, the chopper type power supply circuit It is determined that there is an abnormality in the current consumption of the internal circuit or a decrease in power conversion efficiency due to deterioration of the chopper type power supply circuit itself (step S2). If this is within the normal threshold range, the ripple voltage amplitude applied to the input side capacitor is monitored (step S3), and the ripple voltage amplitude monitored is compared with a correlation table prepared in advance based on the input voltage at that time. If it is out of the range, it is determined that the impedance on the input side capacitor is abnormally increased due to deterioration of the input side capacitor (step S4). If this is within the normal threshold range, it is determined as normal (step 5). With such a configuration and operation, a power supply system abnormality can be detected, and a highly reliable on-vehicle radar device can be obtained.

  By determining whether the duty ratio conversion voltage and the ripple voltage amplitude are within the normal range, the internal circuit consumption current Io of the chopper type power supply circuit increases or decreases (changes) or the power conversion efficiency α decreases (changes). Or, it is judged that the impedance increase abnormality (change) of the input side capacitor of the chopper type power supply circuit is detected, and if the abnormality is recognized, it is reported to the vehicle system side via the communication interface 5 of FIG. To do.

Embodiment 2. FIG.
In monitoring the ripple voltage amplitude applied to the input side capacitor of the chopper type power supply circuit shown in the first embodiment, a necessary and sufficient observation signal range width is set with respect to the effective range width of the AD converter mounted on the microcomputer 4. For the purpose of ensuring, as shown by the peak detection circuit 71 in the case of having a gain shown in FIG. 5, by providing the operational amplifier OP7a with a gain, it is possible to obtain a highly reliable on-vehicle radar device in which erroneous determination is suppressed. Can do. In the example, the feedback voltage of the operational amplifier OP7a is divided by resistors R7d and R7e so as to have a gain. The resistors R7d and R7e also serve as the discharge resistor R7c of the capacitor C7a.

Embodiment 3 FIG.
When the power supply voltage supplied from the vehicle fluctuates greatly, for example, in the unsteady state where the vehicle-side power supply load fluctuation is large, such as engine starter drive or air conditioner compressor drive, the power supply system abnormality described in the first and second embodiments It is conceivable that the fluctuation itself is detected by the detecting means. Therefore, the period when it is determined that the input voltage (corresponding to the supply voltage from the vehicle) obtained by the input voltage acquisition circuit that acquires the input voltage of the chopper type power supply circuit exceeds the predetermined threshold value. Does not detect power system abnormalities. FIG. 7 is a diagram for explaining an abnormality determination procedure of the chopper type power supply circuit according to the third embodiment. Prior to the determination of abnormality, it is determined whether the input voltage is within or outside the threshold value (step S0). If the input voltage is outside the allowable threshold value, the abnormality determination is not performed. If it is within the permissible threshold, the procedure proceeds to step S1 and subsequent steps in the same manner as in the first embodiment so as to determine abnormality. Thereby, erroneous determination can be prevented, and a highly reliable on-vehicle radar device can be obtained.

DESCRIPTION OF SYMBOLS 1 Vehicle-mounted radar apparatus 2 Power supply circuit 3 Radio wave transmission / reception circuit 3a Transmission antenna 3b Reception antenna 3d Transmission circuit 3e Reception circuit 3f VCO (voltage control oscillator)
3g DA converter 3h AD converter 4 Microcomputer (calculation means) 5 Communication interface 6 Positive clamp circuit 7 Peak detection circuit 8 Control IC 9 Duty ratio voltage conversion circuit 13 Input voltage acquisition circuit 14 Output voltage acquisition circuit 15 Battery

Claims (6)

A transmission antenna and a transmission circuit for transmitting radio waves to the detected object;
A receiving antenna and a receiving circuit for receiving the radio wave reflected by the detected object;
A voltage controlled oscillator VCO that determines the frequency of the transmitted radio wave;
A DA converter for controlling the voltage controlled oscillator VCO;
An AD converter that quantizes the frequency difference between the received radio wave received by the receiving circuit and the output of the voltage controlled oscillator VCO;
Arithmetic means for performing radar signal processing for calculating the distance, speed, and angle to the detected object based on the output of the AD converter;
A voltage conversion circuit that converts a supply voltage from the vehicle into a predetermined internal circuit voltage;
In the in-vehicle radar device, the voltage conversion circuit is configured as a chopper type power supply circuit having a constant switching control cycle as an input side power supply circuit.
An input voltage acquisition circuit for acquiring an input voltage of the chopper type power supply circuit;
A duty ratio voltage conversion circuit for converting the duty ratio of the chopper type power supply circuit into a voltage, and a normal correlation table A between the input voltage of the chopper type power supply circuit and the duty ratio conversion voltage;
Comparing the duty ratio conversion voltage obtained by the duty ratio voltage conversion circuit with the correlation table A based on the input voltage obtained by the input voltage acquisition circuit, the internal circuit current consumption abnormality of the chopper type power supply circuit or A vehicle-mounted radar device characterized by detecting a power supply system abnormality of a power conversion efficiency abnormality.   2. The in-vehicle radar according to claim 1, wherein the correlation table A has a voltage width that allows noise as a duty ratio conversion voltage in a normal state with respect to an input voltage of the chopper type power supply circuit. apparatus. Furthermore, a ripple voltage amplitude extraction circuit that extracts a ripple voltage amplitude applied to the input side capacitor of the chopper type power supply circuit;
A normal correlation table B between the input voltage and ripple voltage amplitude of the chopper type power supply circuit,
The ripple voltage amplitude obtained by the ripple voltage amplitude extraction circuit is compared with the correlation table B based on the input voltage obtained by the input voltage acquisition circuit, and the impedance abnormality of the input side capacitor of the chopper type power supply circuit is compared. 3. The in-vehicle radar device according to claim 1, wherein a power supply system abnormality is detected.   4. The vehicle-mounted radar according to claim 3, wherein the correlation table B has a voltage amplitude width that allows noise as a ripple voltage amplitude at a normal time with respect to an input voltage of the chopper type power supply circuit. apparatus.   The ripple voltage amplitude extraction circuit for extracting the ripple voltage amplitude applied to the input side capacitor of the chopper type power supply circuit has a peak detection circuit, and the peak detection circuit has a voltage gain. The on-vehicle radar device according to claim 3 or 4.   The power supply system abnormality is not detected when an input voltage obtained by the input voltage acquisition circuit that acquires an input voltage of the chopper type power supply circuit exceeds an allowable threshold. Item 4. The on-vehicle radar device according to Item 3.