JP2003284320A - On-vehicle dc-dc converter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an on-vehicle DC-DC converter which prevents a power source for an auxiliary machine from being uselessly discharged and can stably operate a control circuit or the like. <P>SOLUTION: The on-vehicle DC-DC converter converts a voltage of a main power source 1 connected to input terminals 10, 11 into a DC voltage having a different amplitude, and supplies the DC voltage to the power source 3 for the auxiliary machine via output terminals 12, 13. The converter comprises a control circuit 22 for controlling a converter main circuit 21, and a voltage detecting circuit 23 for detecting the output voltage of the circuit 21. The converter also comprises a switch means 24 connected to the terminals 12, 13. The converter turns on the means 24 according to a signal from a drive source control unit such as an ECU 5 connected to the power source 3, and supplies the voltage of the power source 3 to the circuit 22 and the circuit 23. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an on-vehicle DC-DC converter mounted on an electric vehicle, a hybrid vehicle, etc.
It relates to a C converter.

[0002]

2. Description of the Related Art Electric vehicles and hybrid vehicles use a motor for driving wheels, a main power supply (main battery) for supplying electric power to a motor drive circuit, and a main power supply voltage converted into a DC voltage of different magnitude. Machine power source (auxiliary battery) and auxiliary machinery (illumination device, air conditioner,
DC that supplies power to various electrical equipment such as car radios
And a DC converter.

Here, the DC-DC converter is a voltage detection circuit for controlling the output voltage to an auxiliary power source or the like at a constant level, and a DC-DC converter when an abnormal voltage is output due to a failure of the DC-DC converter. -It is provided with an overvoltage detection circuit and an undervoltage detection circuit for stopping the DC converter and protecting the auxiliary machine power supply and the auxiliary machine. These voltage detection circuits normally divide the output voltage of the DC-DC converter by resistance and compare it with a reference voltage. On the other hand, the DC-DC converter is adapted to be started / stopped by an on / off signal from a drive source control unit such as an ECU (engine control unit), and a power supply to the control circuit at the time of starting the DC-DC converter. Is supplied from the auxiliary power supply.

As described above, since the output side of the on-vehicle DC-DC converter and the auxiliary power source are always connected, the signal from the ECU is off and the DC-DC converter is stopped. Also in this case, current flows from the auxiliary power supply to various voltage detection circuits and control circuits, and the auxiliary power supply is discharged. If this state continues for a long period of time, the voltage of the auxiliary power supply will drop and DC-
The DC converter cannot be started.

In view of the above, a conventional technique for preventing the discharge of the auxiliary power source when the DC-DC converter is stopped is disclosed in Japanese Patent Laid-Open No. 2000-245139, "On-vehicle power source device and on-vehicle device." Is known as ". FIG. 7 is a circuit diagram showing this conventional technique.
01 is a main power supply, 502 is a power-on switch, 503 is a motor drive circuit, 504 is a wheel drive motor, 505 is a vehicle-mounted power supply device, 506 is a DC-DC converter, 50
Reference numeral 7 is an auxiliary power supply, 508 is an auxiliary power supply, 509 is an auxiliary switch which is interlocked with the power-on switch 502, 510 is a voltage dividing resistor,
Reference numeral 511 is a comparator, 512 is an overvoltage protection circuit, and 513 is a control circuit.

As its operation, the power-on switch 50
2 and the auxiliary switch 509 interlocked therewith are closed via the motor drive circuit 503.
4 is driven, the DC voltage of the main power supply 501 is converted into a predetermined DC voltage by the DC-DC converter 506, the auxiliary power supply 507 is charged, and the auxiliary power 508 is supplied with electric power. On the other hand, the output voltage of the DC-DC converter 506 is divided by the voltage dividing resistor 510 via the auxiliary switch 509 and input to the non-inverting input terminal of the comparator 511. When the voltage exceeds the voltage V _r , an overvoltage detection signal is output from the comparator 511 to the control circuit 513, and the control circuit 513 outputs D
The operation of the C-DC converter 506 is stopped.

When the power-on switch 502 is turned off, the auxiliary switch 509 is also turned off.
The electric circuit on the side is cut off to prevent the discharge current from flowing from the auxiliary power supply 507 to the overvoltage protection circuit 512 and the control circuit 513. As a result, even if the automobile is not used for a long period, if the power-on switch 502 is turned off,
It is possible to prevent discharge of the auxiliary power supply 507.

[0008]

[Patent Document 1] Japanese Unexamined Patent Application Publication No.
In the prior art described in Japanese Patent Application Publication No. 000-245139, a transiently unstable signal is input to the comparator 511 due to chattering of the auxiliary switch 509 accompanying turning on / off of the power-on switch 502, Control circuit 5
There is a problem that the operation of the control circuit 513 becomes unstable or malfunctions when the power supply voltage of 13 is not established. Further, in this conventional technique, the control circuit 5
Power is supplied to the main power supply 501 from the main power supply 501 via the power-on switch 502.
It is necessary to insulate the output of the C converter 506, that is, the auxiliary power supply 507, for system safety. Therefore, although not shown, there is also a drawback that a small switching power supply must be prepared for supplying power to the control circuit 513. Therefore, the present invention is intended to provide an in-vehicle DC-DC converter that prevents unnecessary discharge of an auxiliary power supply, enables stable operation of a control circuit, and eliminates the need for a switching power supply. is there.

[0009]

In order to solve the above-mentioned problems, the invention according to claim 1 converts the voltage of the main power source connected to the input terminal into a DC voltage having a different magnitude and outputs the DC voltage via the output terminal. A vehicle-mounted DC-DC converter for supplying power to an auxiliary device, the control circuit controlling a converter main circuit,
An in-vehicle DC-DC converter including a voltage detection circuit for detecting an output voltage of a converter main circuit, comprising switch means connected to the output terminal, the switch means being connected to an auxiliary power supply, such as an ECU. Is turned on by a signal from the drive source control unit to supply the voltage of the auxiliary power supply to the control circuit and the voltage detection circuit.

According to the present invention, the auxiliary power source is supplied to the control circuit and the voltage detection circuit through the switch means turned on by the drive source control unit. If the detected voltage of the voltage detection circuit is normal, that is, if the voltage of the auxiliary power supply is within the specified range, the voltage detection circuit outputs a signal to the control circuit, and the control circuit outputs an operation signal to the converter main circuit. The converter main circuit converts the voltage of the main power supply into DC voltages of different magnitudes to charge the auxiliary machine power supply and supply power to the auxiliary machine. Further, the output voltage of the converter main circuit is always controlled to be constant by the comparison voltage detection circuit in the voltage detection circuit, even if the main power supply fluctuates in voltage or the consumption current of the auxiliary device changes. When the signal from the drive source control unit is stopped, the switch means is turned off, and the voltage detection circuit and the control circuit are completely disconnected from the auxiliary machine power supply to prevent discharge of the auxiliary machine power supply.

According to a second aspect of the present invention, in the vehicle-mounted DC-DC converter according to the first aspect, the control circuit is
A control unit that controls the converter main circuit and a control voltage detection circuit that detects that the power supply voltage of the control unit has reached a specified value, and an output signal of the control voltage detection circuit and an output signal of the control unit And are used as AND conditions to output the operation signal of the converter main circuit. According to the present invention, it is possible to prevent a malfunction when the power supply voltage of the control unit is not established and is in a transiently unstable state.

According to a third aspect of the present invention, the voltage of the main power source connected to the input terminal is converted into a DC voltage having a different magnitude and supplied to the auxiliary power source through the output terminal.
A drive source control unit connected to an auxiliary power source in a vehicle-mounted DC-DC converter including a control circuit for controlling a converter main circuit and a voltage detection circuit for detecting an output voltage of the converter main circuit The control circuit supplies a voltage of an auxiliary power supply to the control circuit by a signal from the control circuit, and the control circuit controls the converter main circuit and a control for detecting that the power supply voltage of the control section reaches a specified value. A voltage detection circuit is provided, and the switch means connected to the output terminal is turned on by the output signal of the control voltage detection circuit to supply the voltage of the auxiliary power supply to the voltage detection circuit. In the present invention, the drive source control unit directly controls the supply and cutoff of the auxiliary machine power supply to the control circuit. When the auxiliary power supply is cut off, the control voltage detection circuit in the control circuit detects this and turns off the switch means to disconnect the voltage detection circuit from the auxiliary power supply to prevent discharge of the auxiliary power supply.

According to a fourth aspect of the present invention, the on-vehicle DC-DC converter converts the voltage of the main power source connected to the input terminal into a DC voltage having a different magnitude and supplies the DC voltage to the auxiliary power source through the output terminal.
A drive source control unit connected to an auxiliary power source in a vehicle-mounted DC-DC converter including a control circuit for controlling a converter main circuit and a voltage detection circuit for detecting an output voltage of the converter main circuit The second switch means connected to the output terminal is turned on by a signal from the controller to supply the voltage of the auxiliary power supply to the control circuit, and the control circuit controls the converter main circuit; A control voltage detection circuit for detecting that the power supply voltage of the control unit has reached a specified value, and the first switch means connected to the output terminal is turned on by the output signal of the control voltage detection circuit. The voltage of the auxiliary power supply is supplied to the voltage detection circuit.

According to the present invention, the drive source control unit controls the supply and cutoff of the auxiliary power source to the control circuit by turning on and off the second switch means. When the auxiliary power supply to the control circuit is cut off, the control voltage detection circuit in the control circuit detects this and turns off the first switch means to cut off the supply of the auxiliary power supply to the voltage detection circuit. This prevents current from flowing from the auxiliary power supply to the control circuit and the voltage detection circuit, and prevents discharge of the auxiliary power supply.

According to a fifth aspect of the present invention, in the on-vehicle DC-DC converter according to any one of the second to fourth aspects, the control voltage detection circuit has a detection voltage value that enables normal operation of the control circuit. It outputs a signal when it is higher than the minimum operating voltage. According to the present invention, a logic IC
Since the auxiliary power supply is supplied to the voltage detection circuit only when the voltage of the control circuit using the IC, comparator IC, etc. can operate normally, malfunctions in the transient state at the rise and fall of the control voltage are prevented. be able to.

According to a sixth aspect of the present invention, in the on-vehicle DC-DC converter according to any one of the first to fifth aspects, the voltage detection circuit compares the divided voltage value of the detection voltage with a reference voltage. Means for controlling the output voltage of the converter main circuit to be constant and outputting a signal to a control circuit or the like according to the level of the detected voltage with respect to a reference voltage. According to the invention, DC-DC
The output voltage of the converter can be controlled to a predetermined value, and the converter can be controlled to stop at the time of overvoltage or undervoltage due to a failure or the like.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. First, FIG. 1 is a circuit configuration diagram showing a first embodiment of the present invention. In the figure, 1 is a main power source,
Both ends of the main power supply 1 are mounted on a vehicle-mounted DC-DC converter 2
It is connected to the input terminals 10 and 11 of the (converter main circuit 21). The configuration of the converter main circuit 21 is well known and will not be described in detail, but the internal switching elements are operated to convert the DC voltage of the main power source 1 into DC voltages of different magnitudes, and the output terminals 12 and 13 receive the DC voltages. It is what is output.

The output terminal 12 of the DC-DC converter 2,
An auxiliary power source 3 is connected to the auxiliary power source 13, and the various auxiliary devices (lighting device, cooling / heating device,
Various electric components such as a car radio) 4 and an ECU 5 as a drive source control unit are connected in parallel, and the auxiliary power source 3 is charged and electric power is supplied to the auxiliary device 4 and the ECU 5. In this embodiment, a hybrid vehicle is assumed, so the ECU 5 is provided. However, in the case of an electric vehicle,
As the drive source control unit, a control unit of a power converter such as an inverter that drives a motor is used.

The output terminal 12 is connected to one end of a switch means 24 which is on / off controlled by the ECU 5, and the other end thereof is connected to a control circuit 22 and a voltage detection circuit 23 of the converter main circuit 21. ing. With such a configuration, the voltage of the auxiliary power supply 3 is controlled by the control circuit 22 and the voltage detection circuit 2 when the switch means 24 is turned on.
3 is supplied. As the switch means 24, a semiconductor switch, a relay switch, or the like can be used.
The detection output of the voltage detection circuit 23 is added to the control circuit 22.

When the DC-DC converter 2 is started, the EC
The switch means 24 is turned on by the signal from U5, and the voltage of the auxiliary power supply 3 is supplied to the control circuit 22 and the voltage detection circuit 23. Voltage of auxiliary power supply 3 and DC-DC converter 2
A normal or abnormal output voltage is detected by the voltage detection circuit 23, and the detected output is input to the control circuit 22. In the control circuit 22, if the voltage detected by the voltage detection circuit 23 is normal, the converter main circuit 21 is driven to convert the voltage of the main power supply 1 into a DC voltage having a different magnitude, and the output terminal 1
Output to 2 and 13.

When the signal from the ECU 5 is stopped (a stop signal is output), the switch means 24 is turned off. As a result, the voltage of the auxiliary power supply 3 is not supplied to the control circuit 22 and the voltage detection circuit 23, so that the converter main circuit 2
1 stops the operation. At the same time, DC-D from auxiliary power supply 3
Since no current flows through the C converter 2, that is, the control circuit 22 and the voltage detection circuit 23, it is possible to prevent discharge from the auxiliary power supply 3 to the DC-DC converter 2. Although not shown, the converter main circuit 21
Inside, the circuit configuration is such that a current does not flow from the auxiliary machine power source 3 due to a diode in the reverse direction or the like.

Next, FIG. 2 is a block diagram showing the configuration of the control circuit 22 in FIG. The voltage of the auxiliary machine power supply 3 applied to the control circuit 22 via the switch means 24 is applied to the control unit 222 and the control voltage detection circuit 223 via the constant voltage circuit 221. Here, the control unit 222 is a block whose main purpose is to control the converter main circuit 21. The control voltage detection circuit 223 detects whether the power supply voltage (control voltage) of the control unit 222 input from the constant voltage circuit 221 is equal to or higher than a specified value, and outputs a signal when the voltage is equal to or higher than the specified value. This output signal is input to the AND circuit 224 together with the output signal of the control unit 222, and the output signal of the AND circuit 224 is used as an operation signal for the converter main circuit 21.
Note that, in FIG. 2, the signal path indicated by the broken line is not directly related to the embodiment of FIG. 1, and is effective during the circuit operation of FIGS. 3 and 4 described later.

By configuring the control circuit 22 as shown in FIG. 2, the converter main circuit 21 is not activated unless the power supply voltage of the control section 222 is established. That is,
When the power supply voltage is in a transiently unstable state due to ON / OFF of the switch means 24, the converter main circuit 21
It is possible to prevent an erroneous signal from being output.

Next, FIG. 3 is a block diagram showing a second embodiment of the present invention. In the DC-DC converter 2A of this embodiment, the auxiliary power supply 3 is activated by the activation signal of the ECU 5.
Is directly supplied from the ECU 5 to the control circuit 22.
The configuration of the control circuit 22 is similar to that of FIG. 2, and the control voltage detection circuit 223 inside the control circuit 22 uses the path indicated by the broken line in FIG. It is detected that the voltage is equal to or higher than the power supply voltage), the switch means 24 in FIG. 3 is turned on, and the voltage of the auxiliary power supply 3 is supplied to the voltage detection circuit 23. If the voltage of the auxiliary power supply 3 is normal, the signal from the voltage detection circuit 23 is sent to the AND circuit 2 in the control circuit 22 together with the signal from the control unit 222.
24, and the converter main circuit 21 is driven.

On the other hand, when the stop signal is output from the ECU 5, the power supply voltage of the control circuit 22 disappears, so that the converter main circuit 21 stops its operation and the control voltage detection circuit 223 of FIG. 2 turns off the switch means 24. Then, the current flowing from the auxiliary power supply 3 to the voltage detection circuit 23 is cut off.
This can prevent the auxiliary power supply 3 from being discharged.

FIG. 4 is a block diagram showing a third embodiment of the present invention. DC-DC converter 2 of this embodiment
B, the second switch means 25, one end of which is connected to the output terminal 12 of the converter 2B in response to a signal from the ECU 5.
Is turned on to supply the voltage of the auxiliary power supply 3 to the control circuit 22. The control circuit 22 and the voltage detection circuit 2 in FIG.
The connection configuration of the switch 3 and the switch means (first switch means) 24 is the same as in FIG.

In this embodiment, the control voltage detection circuit 223 in the control circuit 22 in FIG.
It is detected that the power supply voltage supplied via the power supply voltage is equal to or higher than a specified value (power supply voltage of the control unit 222), the switch means 24 of FIG.
Supply the voltage of. The following operation is similar to that of the embodiment of FIG. 3, and if the voltage of the auxiliary power supply 3 is normal, the signal from the voltage detection circuit 23 is input to the AND circuit 224 together with the signal from the control unit 222, and the converter main circuit 21 is driven.

In FIG. 4, when the stop signal is output from the ECU 5, the second switch means 25 is turned off, so that the power supply voltage of the control circuit 22 disappears, and at the same time, the control voltage detection circuit 225 loses the specified voltage. When this is detected, the first switch means 24 is turned off, and the supply of the auxiliary power supply 3 to the voltage detection circuit 23 is cut off. This makes E
When the stop signal is output from the CU 5 to the DC-DC converter 2, the first and second switch means 24,
Since all of 25 are turned off, current does not flow from the auxiliary power supply 3 to the control circuit 22 and the voltage detection circuit 23, and the auxiliary power supply 3 can be prevented from discharging.

FIG. 5 shows a specific example of the voltage detection circuit 23 shown in FIGS. 1, 3 and 4, and in this example, the output voltage of the DC-DC converters 2, 2A and 2B is controlled to be constant. 2 shows configuration examples of the comparison voltage detection circuit, the overvoltage detection circuit, and the undervoltage detection circuit.

In FIG. 5, the resistance R₁, R_TwoVoltage divider circuit
Is the output voltage of the DC-DC converters 2, 2A, 2B
It is used to detect the comparative voltage in order to keep it constant.
is there. Amplifier AMP₁One input terminal has a divided voltage V
₁Is input to the amplifier AMP ₁The other input terminal of
Sub-voltage V_r1Is input to the amplifier AMP₁Output
Is input to the control circuit 22. DC-DC converter
The reference voltage V_r1And divided voltage V₁And always
Control is performed so that they are equal.

Next, the voltage dividing circuit of the resistors R ₃ and R ₄ is DC
-To detect an overvoltage state of the output voltage of the DC converters 2, 2A, 2B. To one input terminal of the comparator CP ₂ divided voltage V ₂ is input, and the reference voltage V _r2 is input to the other input terminal of the comparator CP _2,
The output of the comparator CP ₂ is input to the control circuit 22.
Here, during normal operation of the DC-DC converters 2, 2A, 2B, the reference voltage V _r2 is set to a value higher than the divided voltage V ₂ . If an abnormality occurs during the operation of the DC-DC converter and the output voltage rises, and the divided voltage V ₂ becomes higher than the reference voltage V _r2 , the comparator CP ₂ causes the control circuit 22 to operate.
A stop signal is output to. This stops the DC-DC converter, and the auxiliary power supply 3 connected to the output side
And protect the auxiliary machine 4 from overvoltage.

The voltage dividing circuit for the resistors R ₅ and R ₆ is DC
-Detects an insufficient output voltage of the DC converters 2, 2A, 2B. To one input terminal of the comparator CP ₃ divided voltage V ₃ is input, and the reference voltage V _r3 is input to the other input terminal of the comparator CP _3, comparator C
The output of P ₃ is input to the control circuit 22. here,
During normal operation of the DC-DC converters 2, 2A, 2B, the reference voltage V _r3 is set to a value lower than the _divided voltage V ₃ . If abnormality occurs decreases the output voltage during operation of the DC-DC converter, the reference is divided voltage V ₃ voltage V _r3
It becomes lower, stopping the DC-DC converter is output stop signal to the control circuit 22 from the comparator CP _3.

In particular, in the embodiment of FIGS. 3 and 4, the switch
In case of open failure of the switch means 24, 25
The voltage detection circuit 23 becomes inoperable, and
Resistance R of voltage detection circuit₁, R_TwoThe divided voltage of is 0V
It Therefore, the control circuit 22 _r1= V₁Forming a relationship
The control to make it stand up is performed, and as a result, the DC-DC converter
The output voltage of will rise to the limit. Shi
However, if the configuration is as shown in FIG. 5, before the output voltage rises
The undervoltage detection circuit operates and the DC-DC converter
Since it is stopped, abnormal output can be prevented in advance.
It

FIG. 6 shows the control voltage detection circuit 2 in FIG.
23 (a control voltage detection circuit 223 used in the embodiments of FIGS. 3 and 4) is shown. The voltage applied to the control unit 222 is applied to the resistor R at one input terminal of the comparator CP _4.
7 , the voltage V ₄ divided by R ₈ is input, and the comparator C
The reference voltage V _r4 is input to the other input terminal of P ₄ . The comparator CP ₄ outputs a signal when the relationship of V _r4 ≦ V ₄ is established, and turns on the switch means 24.

That is, the comparator CP ₄ is applied only when the voltage applied to the control unit 222 is the specified value (reference voltage V _r4 ) or more.
Can output a signal from. This specified value is used for the IC used in the control circuit 22 (control unit 222),
By setting the value above the minimum operating voltage at which all the circuits can operate normally, the switch means 24 is set to the control circuit 2
Since it is turned on only when the control unit 222 (control unit 222) is in a normally operable state, stable operation is possible without outputting a malfunction signal even in a transient state when the control power supply is turned on and off.

Although not shown, in the embodiments of FIGS. 3 and 4, the switch means 24 and 25 are operated by the output signal of the control voltage detection circuit in the control circuit 22, and this signal is supplied to the control circuit. It is also possible to easily implement the operation signal of the converter main circuit 21 by making an AND connection with the output signal of 22.

[0037]

As described above, according to the present invention, the following effects are expected. 1) In a state where a drive source control unit such as an ECU does not output an operation command to the DC-DC converter, it is possible to completely prevent discharge of the auxiliary power supply. 2) Even if a failure occurs in the control of the DC-DC converter, the overvoltage can be prevented from being output, and the auxiliary power source and the auxiliary device can be reliably protected. 3) By providing the voltage confirmation detecting means such as an AND circuit for monitoring the power supply voltage of the control circuit, stable operation is assured even during a transition accompanying power on / off.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a control circuit in FIG.

FIG. 3 is a circuit configuration diagram showing a second embodiment of the present invention.

FIG. 4 is a circuit configuration diagram showing a third embodiment of the present invention.

5 is a configuration diagram of a voltage detection circuit in FIGS. 1, 3, and 4. FIG.

6 is a configuration diagram of a control voltage detection circuit in FIG.

FIG. 7 is a circuit configuration diagram showing a conventional technique.

[Explanation of symbols]

1 Main Power Supply 2, 2A, 2B DC-DC Converter 3 Auxiliary Power Supply 4 Auxiliary Machine (Various Electrical Equipment) 5 ECU 10, 11 Input Terminal 12, 13 Output Terminal 21 Converter Main Circuit 22 Control Circuit 23 Voltage Detection Circuit 24, 25 Switch means 221 Constant voltage circuit 222 Control part 223 Control voltage detection circuit 224 AND circuit AMP ₁ Amplifier CP ₂ , CP ₃ , CP ₄ Comparator R _{1 to} R ₈ resistance

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takayuki Atsuta             1-1 Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa             Within Fuji Electric Co., Ltd. (72) Inventor Kazuhito Nakahara             1-1 Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa             Within Fuji Electric Co., Ltd. (72) Inventor Koichi Ueki             1-1 Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa             Within Fuji Electric Co., Ltd. F-term (reference) 5H730 AA12 AA20 AS01 AS23 BB57                       BB98 EE60 EE65 FD01 FG01                       VV01 VV06 XC20 XX03 XX12                       XX13 XX23 XX32 XX33 XX44

Claims (6)

[Claims] 1. A vehicle-mounted DC-DC converter for converting a voltage of a main power source connected to an input terminal into a DC voltage having a different magnitude and supplying the DC voltage to an auxiliary power source via an output terminal. In a vehicle-mounted DC-DC converter including a control circuit for controlling the output voltage and a voltage detection circuit for detecting the output voltage of the converter main circuit, switch means connected to the output terminal is provided, An on-vehicle DC-DC converter, which is turned on by a signal from a drive source control unit connected to a machine power supply to supply the voltage of the auxiliary machine power supply to the control circuit and the voltage detection circuit. 2. The on-vehicle DC-DC converter according to claim 1, wherein the control circuit detects a control unit that controls the converter main circuit and that the power supply voltage of the control unit has reached a specified value. A DC-DC converter for a vehicle, comprising: a control voltage detection circuit, and outputting an operation signal of the converter main circuit with an output signal of the control voltage detection circuit and an output signal of the control unit as an AND condition. . 3. A vehicle-mounted DC-DC converter for converting a voltage of a main power source connected to an input terminal into a DC voltage having a different magnitude and supplying the DC voltage to an auxiliary power source via an output terminal. In a vehicle-mounted DC-DC converter including a control circuit for controlling the output voltage and a voltage detection circuit for detecting the output voltage of the converter main circuit, the control circuit is controlled by a signal from a drive source control unit connected to the auxiliary power supply. While supplying the voltage of the auxiliary machine power supply to the control circuit, the control circuit includes a control unit that controls the converter main circuit, and a control voltage detection circuit that detects that the power supply voltage of the control unit has reached a specified value. A vehicle characterized by comprising: supplying a voltage of an auxiliary power supply to the voltage detection circuit by turning on switch means connected to the output terminal by an output signal of the control voltage detection circuit. D use
C-DC converter. 4. A vehicle-mounted DC-DC converter for converting a voltage of a main power supply connected to an input terminal into a DC voltage having a different magnitude and supplying the DC power to an auxiliary power supply via an output terminal, which is a converter main circuit. In a vehicle-mounted DC-DC converter including a control circuit for controlling the output voltage and a voltage detection circuit for detecting the output voltage of the converter main circuit, wherein the output terminal is driven by a signal from a drive source control unit connected to the auxiliary power supply. The second switch means connected to the switch is turned on to supply the voltage of the auxiliary power supply to the control circuit, and the control circuit controls the converter main circuit, and the power supply voltage of the control unit. And a control voltage detection circuit for detecting that the control voltage detection circuit has reached a specified value, and the first switch means connected to the output terminal is turned on by an output signal of the control voltage detection circuit. Serial voltage Automotive DC-DC converter and supplying the voltage of the auxiliary power supply to the detection circuit. 5. The in-vehicle DC-DC converter according to any one of claims 2 to 4, wherein the control voltage detection circuit has a detection voltage value equal to or higher than a minimum operation voltage at which the control circuit can normally operate. An on-vehicle DC-DC converter which outputs a signal at a certain time. 6. The on-vehicle DC-DC converter according to claim 1, wherein the voltage detection circuit includes means for comparing a divided voltage value of the detection voltage with a reference voltage. A means for controlling the output voltage of the converter main circuit by means, and outputting a signal according to whether the detected voltage is higher or lower than a reference voltage.