JP2000346927A - Power supply device for radar - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a noise from being superposed on a radar signal by a constitution wherein, when the radar signal is transmitted and received, the power supply of a radar device is changed over to a separate DC power supply from a switching power supply. SOLUTION: This device 10 is provided with a battery 30, and the input terminal of a switching circuit 32 which comprises a switching element is connected to its positive-pole terminal. One terminal of a capacitor 36 is connected to the output terminal of the switching circuit 32, and the other terminal is grounded. A switching control circuit 34 is connected to the switching element of the switching circuit 32. Normally, it controls the switching element in such a way that an ON-OFF state is changed over at a comparatively high frequency, and it changes over the switching element from an ON state to an OFF state only when a radar signal is transmitted and received. In this state electric power is not supplied from the battery 30, and electric power is supplied from the capacitor 36 by electric energy which is stored in the capacitor 36.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radar power supply, and more particularly to a radar power supply suitable for supplying power to the radar.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Patent Application Laid-Open No. 9-47023
As disclosed in Japanese Unexamined Patent Application Publication No. 2000-163, a switching power supply used as a power supply for an electronic device is known. The switching power supply includes a base power supply and a switching element.
The switching power supply performs power supply by converting the input voltage of the base power supply into a desired DC voltage by switching the switching element at predetermined time intervals. Therefore, according to the above-described conventional switching power supply, it is possible to supply a voltage corresponding to each electronic device to the electronic device with a single power supply.

[0003]

In order to reduce the ripple generated in the output voltage of the switching power supply, it is effective to switch the switching element at a high frequency. However, when switching is performed at a high frequency, in electronic devices arranged around the switching power supply,
Large switching noise may occur. In particular, for example, an in-vehicle millimeter-wave radar device that detects an obstacle existing in a predetermined area in front of a vehicle performs analog processing on a transmission signal and a reception signal when transmitting and receiving a radar signal. For this reason, when such a radar device is supplied with power from a switching power supply during transmission and reception of a radar signal, switching noise tends to be superimposed on the radar signal, and as a result,
An obstacle in front of the vehicle cannot be accurately detected.

[0004] The present invention has been made in view of the above points, and by preventing the occurrence of ripples in the voltage supplied to the radar device when transmitting and receiving radar signals,
An object of the present invention is to provide a radar power supply device capable of reliably avoiding noise superimposition on a radar signal.

[0005]

The above object is achieved by the present invention.
As described in the above, in a radar power supply device having a switching power supply for supplying power to the radar device, a DC power supply separate from the switching power supply, when transmitting and receiving radar signals, the power supply of the radar device from the switching power supply And a power supply switching means for switching to the DC power supply.

In the present invention, when transmitting and receiving radar signals, a DC power supply is used instead of a switching power supply as a power supply for the radar apparatus. That is, when transmitting and receiving radar signals, the radar apparatus is not supplied with power by the switching power supply but is supplied with power by the DC power supply. According to the DC power supply, no ripple occurs in the output voltage.
Therefore, according to the present invention, it is possible to reliably avoid the noise from being superimposed on the radar signal.

In this case, the DC power supply may be a capacitor that can be charged by a switching power supply.

[0008]

FIG. 1 shows a radar power supply (hereinafter simply referred to as a power supply) 1 according to a first embodiment of the present invention.
FIG. 1 shows a system configuration diagram of an in-vehicle millimeter-wave radar device (hereinafter, simply referred to as a radar device) 12 supplied with electric power by a zero. The radar device 12 is mounted on a vehicle, for example, and detects an obstacle existing in a predetermined area in front of the vehicle. The radar device 12 includes an electronic control unit (hereinafter referred to as EC
U), and is controlled by the ECU 14.

As shown in FIG. 1, the radar device 12 includes a transmitting antenna 16 and a receiving antenna 18. The transmitting antenna 16 and the receiving antenna 18 are provided with FM-CW (Freguency Modulation-CW) using millimeter waves as transmission waves.
An on-wave radar is a component of the radar, and is disposed, for example, in the vicinity of a front grill of a vehicle so as to be rotatable around a rotation axis extending in a vertical direction. Transmission antenna 1
The antenna 6 and the receiving antenna 18 are directional antennas, and transmit and receive signals with a predetermined beam angle spread.

The millimeter wave unit 20 including the transmission side circuit and the reception side circuit is built in the ECU 10. The transmitting circuit frequency-modulates a carrier having a predetermined frequency generated from a built-in oscillator. A transmission antenna 16 is connected to the transmission side circuit. The modulated wave signal supplied from the transmission side circuit to the transmission antenna 16 is transmitted in the direction of the steering angle of the transmission antenna 16. When an obstacle exists in the steering angle direction, the transmission signal is reflected by the obstacle, and then the reflected wave is received by the receiving antenna 18. The receiving side circuit is connected to the receiving antenna 18. The receiving-side circuit includes: a reception signal received by the reception antenna 18;
By mixing the transmission signal output from the transmission-side circuit with a transmission signal, a beat signal having a frequency corresponding to the frequency difference between the two is generated.

The millimeter wave unit 20 has an IF (Intermed
iate frequency) amplifier circuit 22 is connected. IF
The amplifying circuit 22 is a circuit that converts a high-frequency beat signal generated by the receiving-side circuit into an intermediate frequency and amplifies it. IF
The amplification circuit 22 is connected to a baseband amplification circuit 24. The baseband amplification circuit 24 is a circuit that demodulates and amplifies a signal output from the IF amplification circuit. A digital signal processor 28 is connected to the baseband amplifier 24 via an AD converter 26. The AD converter 26 converts the signal output from the baseband amplifier circuit 24 from an analog signal to a digital signal. The digital signal processing unit 28 detects a distance and a relative speed between the host vehicle and an obstacle in front of the vehicle based on a reception signal converted from an analog signal to a digital signal.

Next, the power supply device 10 used in the radar device 12 will be described. FIG. 2 shows a system configuration diagram of the power supply device 10 of the present embodiment. As shown in FIG. 2, the power supply device 10 includes a battery 30. Battery 30
Is a standard in-vehicle battery that generates a voltage + B of, for example, 12 volts. The input terminal of the switching circuit 32 is connected to the positive terminal of the battery 30. The switching circuit 32 includes a switching element (not shown) configured by an NPN transistor.

A switching control circuit 34 is connected to the switching elements of the switching circuit 32. The switching control circuit 34 normally performs switching control so that the on / off state of the switching element is switched at a relatively high frequency. The switching circuit 32
The power supply voltage of the battery 30 is stepped down to a voltage (for example, 6 volts) corresponding to the ratio of the ON time and the OFF time of the switching element, and output. Hereinafter, the battery 30, the switching circuit 32, and the switching circuit 34 are referred to as a switching power supply 35. Further, the switching control circuit 34 keeps the switching element in the switching power supply 35 in the off state at a predetermined time as described later.

One terminal of a capacitor 36 is connected to the output terminal of the switching circuit 32. The other terminal of the capacitor 36 is grounded. Capacitor 36
Have a capacity selected to be able to store a predetermined amount of electrical energy. The capacitor 36 stores electric energy when the output voltage of the switching circuit 32 is applied, and outputs a charging voltage when no voltage is applied.

The output terminal of the switching circuit 32 and
And a dropper regulator at one end of the condenser 36.
38 input terminals are connected. Dropper regular
The variable resistor 38 has a built-in variable resistor and changes its resistance.
The output voltage of the switching circuit 32 or
Adjusts the output voltage of the capacitor 36 and outputs it. the above
According to the configuration, the power supply voltage + B of the battery 30 is stepped down.
Voltage V obtained _ccIs supplied to the radar device 12.
Can be Therefore, the radar device 12 is
Voltage V output from 10_ccOperates as power supply voltage
You.

Incidentally, the voltage output from the switching power supply 35 generally has a ripple. In order to reduce the ripple of the power supply voltage supplied to the radar device 12, it is effective to perform the switching operation of the switching element built in the switching circuit 32 at a high frequency. However, in the radar apparatus 12 of the present embodiment, as described above, when transmitting and receiving the radar signal, the analog processing of the radar signal is executed. In the power supply device 10 that supplies power to the radar device 12, when the switching of the switching element is performed at a high frequency in order to reduce the ripple of the power supply voltage during the analog processing of the radar signal, large switching noise is superimposed on the radar signal. I will. Therefore, when transmitting and receiving radar signals, it is not appropriate to switch the switching elements at high frequencies. Therefore, the power supply device 10 used in the radar device 12
Therefore, it is necessary to reduce the ripple of the power supply voltage supplied to the radar device 12 without switching the switching element at a high frequency when transmitting and receiving radar signals.

In order to realize the above functions, the power supply device 10 according to the present embodiment uses the radar device 1 when transmitting and receiving radar signals.
The second power supply is switched from the switching power supply 35 to the capacitor 36. According to the capacitor 36,
No ripple occurs in the output voltage. In the radar device 12, transmission and reception of a radar signal are performed at predetermined intervals. That is, the time required for digital processing of a radar signal is relatively long, while the time required for analog processing of a radar signal is short. For this reason, if the capacitor 36 is used instead of the switching power supply 35 as the power supply of the radar device 12 only during the analog processing of the radar signal, the voltage supplied to the radar device 12 can be prevented from dropping sharply. By supplementing the electric energy lost by the capacitor 36 with the output voltage of the switching power supply 35 during the digital processing of the radar signal, a period for sufficiently charging the capacitor 36 is secured. Therefore, according to the above method, it is possible to avoid the occurrence of ripple without switching the switching element at a high frequency, and to always supply an appropriate voltage to the radar device 12.

FIG. 3A shows a radar apparatus 12 according to this embodiment.
FIG. 5 is a diagram showing a time change of the processing content of the radar signal in FIG. FIG. 3B is a diagram illustrating an on / off state of the switching power supply 35 built in the power supply device 10 of the present embodiment. FIG. 3C is a diagram showing a time change of an input voltage appearing on the input side of the dropper regulator 38 when the switching power supply 35 is controlled as shown in FIG. 3B.

As shown in FIGS. 3A and 3B, the switching control circuit 34 controls the switching power supply 35 only during a period during which the radar apparatus 12 performs analog processing on a transmission / reception signal of a radar signal (when transmitting / receiving a radar signal). Turn off. Specifically, the switching operation at a high frequency of the switching element built in the switching circuit 32 is switched from the on state to the off state. When such a state is realized, power is not supplied from the switching power supply 35, and power is supplied from the capacitor 36 by the electric energy stored in the capacitor 36. Therefore, according to the power supply device 10 of the present embodiment, when transmitting and receiving the radar signal,
Can be used to supply power to the radar device 12.

As shown in FIG. 3C, the output voltage of the switching power supply 35 has a ripple, while the output voltage of the capacitor 36 has no ripple. For this reason, when transmitting and receiving radar signals, it is unnecessary to perform switching at a high frequency in order to reduce ripples in the voltage supplied to the radar device. If the switching is not performed at a high frequency, no switching noise is superimposed on the radar signal. Therefore, according to the power supply device 10 of the present embodiment, when transmitting and receiving the radar signal, the power supply of the radar device 12 is switched from the switching power supply 35 to the capacitor 36, so that the switching noise is prevented from being superimposed on the radar signal. be able to. As a result, according to the radar device 12 of the present embodiment, it is possible to accurately detect an obstacle existing in front of the vehicle.

In addition, during the digital processing of the radar signal, even if the power supply voltage supplied to the radar device 12 has a ripple, the ripple does not cause any inconvenience. For this reason, in the present embodiment, it is possible to suppress the switching frequency of the switching power supply 35 to a low frequency during the digital processing of the radar signal. If the switching frequency is kept low, the generation of switching noise is suppressed and the loss due to switching is reduced, so that it is not necessary to provide the switching power supply 35 with the high-performance switching circuit 32. Therefore, according to the present embodiment, it is possible to configure the power supply device 10 with a small and inexpensive switching power supply 35.

Next, a power supply device 50 according to a second embodiment of the present invention will be described. In the power supply device 50 of the present embodiment, in the power supply device 10 shown in FIG. 2, the switching control circuit 34 controls the switching elements so that the voltage output from the switching circuit 32 increases immediately before the transmission and reception of the radar signal. It is realized by doing.

When the power supply from the capacitor 36 continues for a long time, the output voltage of the capacitor 36 drops. If such a situation occurs, there is a possibility that a desired power supply voltage cannot be secured in the radar device 12. Therefore, when power is supplied by the capacitor 36, the capacitor 36 is set at the start of transmission / reception of the radar signal so that the minimum voltage is secured during transmission / reception of the radar signal.
It is appropriate to output a large voltage from the. In order to output a large voltage from the capacitor 36, it is effective to increase the output voltage of the switching power supply 35 immediately before starting transmission and reception of a radar signal.

The power supply device 50 of this embodiment is characterized in that the switching control circuit 34 controls the switching of the switching elements as described above in order to supply the radar device 12 with appropriate power when transmitting and receiving radar signals. are doing. Hereinafter, with reference to FIG. 4, a characteristic portion of the power supply device 50 of the present embodiment will be described. FIG. 4A is a diagram illustrating a temporal change in the processing content of the radar signal in the radar device 12 of the present embodiment. FIG. 4B is a diagram illustrating a change over time of a target output voltage of the switching power supply 35 built in the power supply device 50 of the present embodiment. FIG. 4C is a diagram showing a time change of a voltage appearing on the input side of the dropper regulator 38 when the switching power supply 35 is controlled as shown in FIG. 4B.

As shown in FIGS. 4A and 4B, the switching control circuit 34 is built in the switching circuit 32 only for a predetermined period t immediately before the radar apparatus 12 starts analog processing of a transmission / reception signal of a radar signal. The output voltage of the switching power supply 35 is increased by increasing the ratio of the ON time of the switching element. In this case, the electric energy stored in the capacitor 36 increases. Under this situation, when analog processing of the transmission / reception signal of the radar signal is started, that is, when the switching control circuit 34 switches the switching operation of the switching element from the ON state to the OFF state, a large voltage is output from the capacitor 36. become. For this reason, FIG.
As shown in (C), even if the output voltage of the capacitor 36 drops during transmission / reception of the radar signal, the power supply voltage supplied to the radar device 12 is prevented from being unduly reduced.

Also in this embodiment, the capacitor 3
No ripple is generated in the output voltage of No. 6, so that the switching noise is superimposed on the radar signal as in the case of the first embodiment. Therefore, according to the power supply device 50 of the present embodiment, it is possible to reliably prevent the switching noise from being superimposed on the radar signal while preventing the power supply voltage supplied to the radar device 12 from being unduly reduced.

In the first and second embodiments, the capacitor 36 corresponds to the "DC power supply" described in the claims, and the switching control circuit 34 operates when transmitting / receiving a radar signal. , Switching circuit 3
The power supply of the radar device 12 is switched from the switching power supply 35 to the capacitor 36 by changing the switching operation of the switching element incorporated in the switching device 2 from the ON state to the OFF state.
The "power supply switching means" described in the claims is realized by switching to.

In the first and second embodiments, the radar device 12 has the configuration as shown in FIG. 1. However, the configuration of the radar device 12 is not limited to this. Method, number of antennas, IF
The radar device may be realized by a configuration different from the above embodiment, such as the presence or absence of the amplifier circuit 22.

[0029]

As described above, according to the first and second aspects of the present invention, at the time of transmitting and receiving a radar signal, it is possible to prevent a ripple from occurring in the voltage supplied to the radar apparatus, thereby generating noise in the radar signal. Overlap can be reliably avoided.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram of an in-vehicle millimeter-wave radar device supplied with power by a radar power supply device according to an embodiment of the present invention.

FIG. 2 is a system configuration diagram of a radar power supply device of the present embodiment.

FIG. 3A is a diagram illustrating a temporal change in the processing content of a radar signal in the radar device according to the present embodiment. FIG. 3B is a diagram illustrating the on / off state of the switching power supply incorporated in the power supply device according to the present embodiment. FIG.
FIG. 3C is a diagram showing a time change of a voltage appearing on the input side of the dropper regulator when the switching power supply is controlled as shown in FIG. 3B.

FIG. 4A is a diagram illustrating a temporal change in processing content of a radar signal in a radar apparatus according to a second embodiment of the present invention. FIG. 4B is a diagram illustrating a change over time of a target output voltage of a switching power supply incorporated in the power supply device of the present embodiment. FIG. 4C shows that the switching power supply is
FIG. 6 is a diagram illustrating a time change of a voltage appearing on the input side of the dropper regulator when the control is performed as illustrated in FIG.

[Explanation of symbols]

 10, 50 Radar power supply (power supply) 12 In-vehicle millimeter-wave radar (radar) 16 Transmitting antenna 18 Receiving antenna 30 Battery 32 Switching circuit 34 Switching control circuit 35 Switching power supply 36 Capacitor

Claims (2)

[Claims] 1. A radar power supply device comprising a switching power supply for supplying power to a radar device, wherein a power supply for the radar device is transmitted from the switching power supply when transmitting / receiving a radar signal to / from a DC power supply separate from the switching power supply. And a power supply switching means for switching to the DC power supply. 2. The radar power supply device according to claim 1, wherein the DC power supply is a capacitor that can be charged by the switching power supply.