JP2769050B2 - DC-DC converter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC-D converter for converting a high voltage of a DC power supply such as a battery into a predetermined DC voltage and outputting the converted DC voltage.
Regarding the C converter, especially in the control for controlling the temperature of the internal elements of the sealed case, measures are taken to reduce the consumption of dark current such as a temperature switch in a region where the temperature is not controlled.
It relates to a C-DC converter.

[0002]

2. Description of the Related Art In recent years, the applicant has proposed a system in which a vehicle having a diesel engine is provided with a retarder control device. The system of the retarder control device includes an induction motor that operates as an electric motor and a generator mounted on a drive system of a diesel engine, and controls the power generation mode of the induction machine to perform electric braking to increase an engine braking effect. Energy is converted into electric energy and regenerated so as to charge the battery. Further, the basic configuration is that auxiliary acceleration is performed by electric mode control of the induction machine by a battery power source, engine output is increased, and exhaust gas is reduced. On the other hand, the DC power supply of the battery in this case can be used for other purposes. For this reason, the DC power is converted into a predetermined DC voltage by a DC-DC converter, and is also used for various electric components of a diesel engine and a vehicle. Power is supplied. In addition, the electric power used to control such an induction machine is inevitably large. On the other hand, if a large current type is set, measures such as thickening the coil of the induction machine and reducing the resistance will be required, and Increase and the problem of electric leakage are not preferred. Therefore, the power control system of the induction machine is set to a high voltage type, and therefore, the power supply voltage of the battery is also set to the high voltage. Therefore, the DC-DC converter is configured as a constant voltage type capable of efficiently converting a high voltage to a low voltage, and further responds to various electrical demands on the electrical component side, and includes an internal element of the module. It is necessary to take measures such as sufficient temperature control.

Conventionally, as described above, a DC-D which is adapted to a large-capacity DC power supply, has a high efficiency and a relatively large voltage conversion rate.
The C converter is configured as a switching type constant voltage power supply circuit. That is, a rectifier circuit is combined with a DC-AC inverter, and an input DC voltage is converted into a high-frequency input by a switching circuit having a power transistor and the like, the high-frequency input is transformed by a power transformer, and a pulse flows out by a diode. The power is taken out, rectified by a rectifier circuit of a capacitor, and smoothed by a filter circuit of a choke coil to output a predetermined DC voltage. Further, the switching frequency of the switching circuit is adjusted by the control circuit in accordance with the change in the output voltage, and the switching frequency is maintained at a constant voltage.
On the other hand, in this constant voltage type, a protection circuit for preventing an overcurrent is provided in order to prevent an overcurrent from flowing due to a short-circuit of an output terminal or the like and destroying various elements. Furthermore, D
Describing the structure of the C-DC converter, a plurality of modules having the above-described voltage conversion function are mounted in parallel in a closed case. The case is made of a material such as aluminum alloy with good thermal conductivity, and has a large number of radiating fins. Temperature control.

[0004]

However, in the configuration of the above-mentioned conventional DC-DC converter, the DC-DC converter is always converted to a rated DC voltage. In addition, the current is limited to the rated output current or less by the limiting current value of the overcurrent protection circuit, and the case side is equipped with natural air cooling heat dissipation measures,
This alone may result in insufficient temperature control of the internal elements. That is, on the output side of the DC-DC converter, radios, headlights, wipers, air conditioners,
When power supplies of various systems are connected and a large number of these electrical components are used at the same time, a current near the rated output current flows continuously. At this time, the operation rate of the DC-DC converter increases, and the amount of heat generated by the internal element increases in accordance with the output current. However, since the heat radiation efficiency on the case side is constant, the internal element temperature and the internal element temperature increase. Will rise. In particular, when the DC-DC converter is mounted outside the vehicle, the heat radiation efficiency of the case is greatly affected by the outside air temperature, and in a situation where the outside air temperature is high, the temperature rise of the internal elements further increases. Here, since the operating temperature of the internal element is determined in advance, the temperature of the internal element may rise to the operating temperature or higher in the above-described case, and the internal element may be damaged. For this reason, in a DC-DC converter mounted on a vehicle, a measure for more reliably managing the internal element temperature is required in consideration of the influence of the outside air temperature and an increase in power consumption.

[0005] Incidentally, in the management control of the internal element temperature, a temperature sensor and a temperature switch for detecting the temperature are required, and the temperature sensor and the like are connected to the output side of the DC-DC converter. In this case, when the power supply source of the DC-DC converter is a battery or the like, the power consumption is large if power is constantly consumed by the temperature sensor or the like. Internal element temperature management is not required in normal power supply conditions, but only when the load current on the electrical component suddenly increases and the internal element temperature rises, thus consuming dark current in areas where temperature is not controlled. As much as possible.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to reduce the dark current of a temperature switch in controlling the temperature management of an internal element of a module mounted inside a sealed case. DC that can be reduced
-To provide a DC converter.

[0007]

In order to achieve this object, the present invention, as shown in FIG.
A DC voltage input with means 21-26 for converting a predetermined DC voltage by the switching system is limited based on the reference voltage and the rated output current of the comparison voltage and compared to the sensed locations constant the overcurrent due to load current DC- including an overcurrent detection circuit 27
It is an improvement of the DC converter. The characteristic configuration is
The overcurrent detection circuit 27 includes a current reduction circuit 31 for adding a constant bias voltage to the comparison voltage, and an internal element is provided between the current reduction circuit 31 and the output of the module 20a.
A temperature switch 32 which detects a child temperature and turns on and off at a predetermined temperature by itself is connected in series. This
The DC-DC converter constituted urchin, electrostatic only when the temperature switch 32 is turned on inside the device temperature rises
Since current flows through the current reduction circuit 31 , the current reduction circuit 31
Is controlled so as to suppress the increase in the internal device temperature by forcibly lowering the load current, the current reduction circuit 31 temperature switch 32 is turned off in the region where the thermal switch 32 inside the element temperature is low is not turned off and temperature control No current flows in
Thus, consumption of dark current can be eliminated.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the principle of the DC-DC converter of the present invention,
It is a lineblock diagram showing an example applied to a diesel engine with a retarder. First, a system of a retarder control device for a diesel engine will be described. An induction machine 11 that operates as an electric motor and a generator is mounted on a flywheel 2 of a drive system of a diesel engine 1.
Are connected via the clutch 3 to the transmission 4 and thereafter.
The retarder control device 10 is configured such that the induction machine 11 is connected to a battery 13 via an inverter circuit 12 so as to be able to control the power, and the control circuit 14
The battery circuit power is supplied to the induction machine 11 by the inverter circuit 12 and an advanced rotating magnetic field is generated by the inverter circuit 12 to operate as an electric motor to perform auxiliary acceleration. The inverter circuit 12 generates a rotating magnetic field delayed by the induction machine 11 by the power generation mode signal, operates as a generator to perform electric braking, and regenerates electric energy generated at this time to charge the battery 13. You.

Next, a description will be given of a power supply system for various electric components by the DC power supply of the battery 13.
The DC-DC converter 20 is connected to 13. This DC-
The positive output side of the DC converter 20 is a clock 5 and a tachometer 6
And a radio, a headlight, a wiper, and the like via a switch 8 which is turned on at an ACC position of a key switch 7.
It is connected to electrical components 15 such as an air conditioner. The DC-DC converter 20 is mounted outside the vehicle, and a plurality of modules 20a are mounted in parallel in a sealed case 20b. The case is made of a material having good thermal conductivity, and has a large number of radiating fins 20c so that it can be naturally cooled.

A description will be given of one module 20a. The module 20a has a switching circuit 21 connected to the battery 13, and this switching circuit 21 is connected to the power transformer 22, the rectifier circuit 23, and the filter circuit 24. It is configured to convert DC voltage to a predetermined DC voltage by switching method and output it.
You . A voltage detection circuit 25 is connected to the output side, and this circuit 2
5 by the output voltage and the deviation calculated et between the reference voltage of the rated
It is the switching frequency of the switching circuit 21 is Ru is adjusted by the control circuit 26 in accordance with the deviation. Further, a reference voltage circuit 28, a comparison voltage circuit 29, and an overcurrent detection circuit 27 having an operational amplifier 30 for comparing both voltages are connected , and this circuit 27 compares the reference voltage with a comparison voltage based on a load current of a predetermined resistance. , the load current increases above the rated output current, and the current limit output a limiting signal to the control circuit 26 from the operational amplifier 30, configured to feed back control. The current reduction circuit 31 to the comparison voltage circuit 2 9 of the overcurrent detection circuit 27 is connected so as to increase the change by adding a bias voltage to the comparison voltage. On the other hand, a temperature switch 32 for detecting the internal element temperature T is provided inside the case 20b. This temperature switch 32 is provided at least in some places to reduce dark current at low temperatures.
The temperature switch 32 is turned on and off at a constant temperature, and the temperature switch 32 is connected to the constant voltage source V _REF2 of the current reduction circuit 31 and the positive electrode.
Is connected between the connection L _1, it has been possible only energized to operate the current drop circuit 31 when the temperature switch 32 is turned on.

Next, the operation of this embodiment will be described. The retarder control device 10 is controlled in a power generation mode when the vehicle is running normally and when braking, and the diesel engine 1
The battery 13 is charged by regenerating the electric energy generated by the induction machine 11 of the drive system. And this battery 13
Is supplied to the induction machine 11 when the retarder control device 10 is controlled in the electric mode during acceleration, and is used for auxiliary acceleration. The DC high voltage of the battery 13 is DC-DC
Is converted to high-frequency input switching circuit 21 of the module 20a of the converter 20, is converted by the power transformer 22 to a predetermined voltage, the rectifier circuit 23 is rectified by further Fi <br/> is smoothed by filter circuit 24 of a given Converted to low DC voltage. At this time, the output voltage is constant voltage control, and of being current limited by the overcurrent detection, thus Ru is output voltage and current rating. Then, this rated voltage is applied to the timepiece 5, the tachometer 6, and the various electrical components 15, and a current corresponding to the load flows to supply power normally, and the battery power is also used for the low-voltage electrical components 15 and the like. You. On the other hand, when the DC-DC converter 20 operates as described above to supply power to the electrical component 15 and the like, the temperature switch 3 is provided inside the case 20b.
2, the internal element temperature T is detected. When the internal element temperature T is low, the temperature switch 32 is turned off to turn off the power.
The flow reduction circuit 31 is turned off . Therefore, the comparison voltage of the overcurrent detection circuit 27 of the module 20a is set by the normal load current, whereby the load current can be increased to the rated output current. On the other hand, when the internal element temperature T rises above a predetermined temperature, the temperature switch 32 is turned on only in this case, and the current reduction circuit 31
Electric current flows . Then, power is supplied to the current reduction circuit 31, and the bias voltage is added to the comparison voltage.
For this reason, the difference from the reference voltage for overcurrent detection is reduced, and the range of increase in the load current is limited. Therefore, in a situation where a large load current flows and power is supplied to many electrical components 15, the current is immediately limited by the overcurrent detection, and the load current is forcibly reduced. Is suppressed, and breakage of the internal element is prevented.

[0012] Figure 2 is a circuit diagram showing a specific example of the overcurrent detection circuit 27, a reference voltage circuit 28 is a positive electrode connection L
A constant voltage source V that is connected in series between the ₁ and the negative electrode connection L _2
REF1 and two resistors Ra, have a Rb, the resistors Ra, R
b of the connection points Ru is connected to the positive input of the operational amplifier 30.
Comparison voltage circuit 29 provided in the anode connection L ₂ resistor Rs
The resistor Rs is connected to the operational amplifier 3 via a resistor Rc.
Ru is connected to the inverting input of 0. The current reduction circuit 31
And MOS transistor Q ₁ resistance Re and a constant voltage source V _REF2
Having. The drain of the MOS transistor Q ₁ is resistance Rc
With the resistor Rf connected in parallel with the operational amplifier 30
Is connected to the phase input, the source of the MOS transistor Q ₁ is
It is connected to a constant voltage source V _REF2 via a resistor Re . The temperature switch 32 mounted inside the case 20b is turned on.
Temperature is slightly lower than the maximum temperature T _{0 at} which the internal elements can operate.
It is have detected temperature T ₁ is set, the temperature of off operation is the detection temperatures T ₁ than had little low return temperature T ₂ is set, these temperatures T _1, itself on at T _2, off to have a hysteresis < is configured. And this temperature switch 32
There is connected between the constant voltage source V _REF2 and the positive electrode connecting L _1, M
The gate of the OS transistor Q ₁ is also connected to the constant voltage source V _REF2
Ru is.

[0013] By this embodiment, the reference voltage V _a of the positive-phase input of the operational amplifier 30 is a constant voltage source V _{RE F1,} resistors Ra, Rb
V _a = V _REF1 · Rb / (Ra + Rb) Therefore, normal internal element temperature T may detect temperatures T ₁ following low temperature switch 32 is MOS transistor Q ₁ is also turned off to turn off, current drop circuit 31 is de-energized. Therefore, the comparison voltage _Vb of the negative-phase input of the operational amplifier 30 is equal to the resistance Rs of the comparison voltage circuit 29 and the load current Ib.
V _b = Rs · I, which are shown in FIG. Therefore, the load current I is small, in the case of V _b <V _a is in the "I" point of FIG. 3, the comparison voltage V _b with the load current I
There becomes equal to or larger than the reference voltage V _a increases, are over-current detection is limited to V _b = V _a operational amplifier 30,
The load current I in this case is the rated output current I _{K1 at the} point “C”. On the other hand, when the internal element temperature T rises above the detection temperature T ₁ and the temperature switch 32 is turned on, power is supplied to the constant voltage source V _REF2 to turn on the MOS transistor Q ₁ , and the resistances Re and Rf of the current lowering circuit 31 are turned on. Is energized. For this reason,
A constant voltage source V _REF2, the resistance Re, the bias voltage V _c by the combined resistance Rg of the resistor Rc and Rf are set as follows. _{V c = V REF2 · Rg /} (Rg + Re) Then, the bias voltage V _c is that which is added to the comparison voltage V _b, the comparison voltage V _b3 of the total increase in the following manner. V _b3 = V _b + V _c Therefore, the comparison voltage V with respect to this case the reference voltage V _a
b3 are compared, and the load current I _K3 at the point “B” in FIG.
The condition of V _b3 = V _a is satisfied as at the point “d”, an overcurrent is detected, and the current is limited to this load current I _K3 .

FIG. 4 is a time chart showing the temperature control of the internal elements by the temperature switch 32. When off the key switch 7 is an internal device temperature T is in a slightly higher than the outside air temperature T _3, when turning on the key switch 7 at t1, powered from module 20a to electrical equipment 15 or the like is started, depending on the load state When the module 20a operates and the load current I
Flows, and the internal element temperature T also gradually increases. In this case, if the load on the electrical component 15 is light and the load current I is small,
Since the internal elements generate little heat, the heat is sufficiently radiated by natural air cooling on the case 20b side. On the other hand, the load current when I is increased or or the outside air temperature T ₃ higher conditions, the only natural air cooling is insufficient heat dissipation, internal element temperature T inside the device at t2
When the temperature reaches the detection temperature T ₁ of the temperature switch 32 lower than the operable maximum temperature T ₀ , the load current I is forcibly reduced as described above, and the internal element temperature T gradually decreases. I do. When reaching the return temperature T ₂ at t3, the load current I by turning off the thermal switch 32 increases and returns to the original, is as increases again inside the device temperature T accordingly. In this manner, the return and the forcible decrease of the load current I are repeated, and the internal element temperature T becomes operable.
Temperature T _{1 of the} temperature switch 32 lower than the maximum temperature T ₀
Nearly constant control is performed in the vicinity. At this time, in a region where the internal element temperature T is low and the temperature is not controlled, such as between t1 and t2 or after t3, the temperature switch 32 is turned off and no current is supplied, and the temperature switch 32 and the current reduction circuit 31 are turned off.
And no current is consumed. Then, the temperature switch 32 is turned on only in the temperature control region between t2 and t3, and current flows through the temperature switch 32 and the current reduction circuit 31 to be consumed.

Although the embodiment of the present invention has been described above, the connection between the temperature switch and the current reduction circuit is not limited to the embodiment. It goes without saying that the DC-DC converter can be applied to all uses other than the embodiment.

[0016]

As described above , according to the present invention ,
For example, the overcurrent detection circuit applies a constant bias voltage to the comparison voltage.
A current reduction circuit for addition is provided.
The internal element temperature is detected between the output of the
Temperature switches that turn on and off at a time
Therefore, the dark current is greatly reduced, which is particularly advantageous in the case of a battery power supply source. The temperature at which it turns itself on and off
Connect a switch directly between the current reduction circuit and the module output.
Since they are connected to the columns, the current consumption of the current reduction circuit is reduced, and the operation can be reliably performed with a simple configuration.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a principle of a DC-DC converter according to the present invention in a state applied to a diesel engine with a retarder.

FIG. 2 is a circuit diagram showing specific examples of a reference voltage circuit, a comparison voltage circuit, a current reduction circuit, and a temperature switch in the overcurrent detection circuit.

FIG. 3 is a diagram showing an operation state in a normal state and in an internal element temperature rise.

FIG. 4 is a diagram showing a time chart of internal element temperature control by a temperature switch.

[Explanation of symbols]

Reference Signs List 20 DC-DC converter 20a module 21 switching circuit 22 power transformer 23 rectifier circuit 24 filter circuit 25 voltage detection circuit 26 control circuit 27 overcurrent detection circuit 28 reference voltage circuit 29 comparison voltage circuit 30 operational amplifier 31 current reduction circuit 32 temperature switch

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Atsushi Obata 3-1-1, Hinodai, Hino-shi, Tokyo Inside the Hino Plant of Hino Motors, Ltd. (72) Kunitoshi Shimizu 3-chome, Hinodai, Hino-shi, Tokyo No. 1 Hino Motors, Ltd. Hino Plant (72) Inventor Shuichi Oi 3rd Hayakawa, Hayakawa, Nitta-machi, Nitta-gun, Gunma Prefecture Sawafuji Electric Co., Ltd. Nitta Plant (72) Inventor Hiroshi Fujihashi Tokyo Integran Co., Ltd., 4-6-1, Ueno, Taito-ku (72) Inventor Kuniharu Ogawa Integran Co., Ltd. 4-6-17-1, Ueno, Taito-ku, Tokyo (72) Inventor Teiji Kumagai, Taito-ku, Tokyo Ueno 4-6-7-301 Integran Corporation (58) Field surveyed (Int.Cl. ⁶ , DB name) H02M 3/00-3/44

Claims (2)

(57) [Claims] A means (21) for converting a DC voltage input to a module (20a) into a predetermined DC voltage by a switching method.
And to 26), the DC-DC converter with overcurrent detection circuit (27) for comparing the comparison voltage by the reference voltage and the load current to limit the overcurrent to the rated output current of the detected stations constant, the overcurrent detection circuit (27) comprises a current reduction circuit (31) for adding a constant bias voltage to the comparison voltage, the internal element temperature between the output of the current reduction circuit (31) and the module (20a) , And a temperature switch (32) that turns on and off at a predetermined temperature by itself is connected in series.
C-DC converter. 2. A predetermined time when the temperature switch (32) is turned on.
If the temperature is lower than the maximum operable temperature (T ₀ )
Temperature (T ₁ ) where the temperature switch (32) turns off
The fixed temperature is the return temperature (T ₂ ) lower than the detection temperature (T ₁ ).
DC-DC converter of claim 1, wherein that.