JPH087637B2 - Electronic equipment power supply - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device for electronic equipment, and more particularly to a power supply device for electronic equipment that operates stably in a temperature range from high temperature to low temperature.

2. Description of the Related Art Electronic devices generally have a power supply unit for driving a load such as a circuit. The power supply unit needs to stably supply a constant voltage to the load, and for example, a switching regulator is used. On the other hand, electronic devices are used under all conditions and sometimes at low temperatures.

Conventionally, it has been difficult to use an electronic device at low temperature, especially an electronic device having a mechanically movable portion, to operate stably due to an increase in load due to an increase in friction.

Therefore, when the electronic device is used at a low temperature, a heater or the like is provided in the device in advance, and the heater or the like is controlled to increase the temperature in the device before use.

However, mounting a heater or the like in an electronic device is
Installation space is required. Further, when the heater or the like is controlled by a thermostat or a thyristor, the influence of noise is great. Further, a dedicated separate power source and control circuit are required to continuously control the heater and the like.

Then, this invention is made | formed in view of the said subject, and an object of this invention is to provide the power supply device of the electronic device which can operate an electronic device stably from high temperature to low temperature.

Means for Solving the Problems The present invention, when using an electronic device at a high temperature, minimizes heat generation from a power supply unit in order to prevent an internal temperature rise of the device, and uses the electronic device at a low temperature. In order to positively increase the temperature in the device in the case of doing so, attention is paid to the fact that the power loss in the power supply unit is converted into heat.

FIG. 1 shows a block diagram of the principle of the present invention. In Figure 1,
Between the DC voltage DC (+) and the ground GND, it is connected to the load 3 via the first power supply unit 1 and the second power supply unit 2, and the sensor unit 4 is connected to the first power supply unit 1. There is.

The sensor unit 4 changes its output signal depending on the ambient temperature. The first power supply unit 1 is for supplying electric power to the load 3, and when the ambient temperature is lower than the specified temperature, the output power is higher than the specified power according to the output signal of the sensor unit 4. Make a big change. Further, the second power supply unit 2 is interposed between the first power supply unit 1 and the load 3, and supplies a predetermined power of the output power from the first power supply unit 1 to the load 3,
Converts other power into heat loss.

Action As shown in FIG. 1, the sensor unit 4 detects the ambient temperature and changes its output signal. Due to this change in the output signal, the first power supply unit 1 greatly changes the output power when the ambient temperature is lower than the regulation. That is, at low temperatures, the change in the output signal of the sensor unit 4 causes the output voltage of the first power supply unit 1 to be larger than that at room temperature or higher.

On the other hand, the second power supply unit 2 constantly supplies a predetermined amount of output power to the load 3, and changes the other power into heat loss. Therefore, when the output voltage of the first power supply unit increases at low temperature, the heat loss increases accordingly. This heat loss raises the temperature inside the electronic device.

Therefore, even when the electronic device is used at a low temperature, it is not necessary to separately provide a heating device such as a heater, and it is possible to raise the temperature inside the device and thereby stably operate the device. Become.

Further, under high temperature, it is possible to control by the signal from the sensor unit 4 so that the first power supply unit 1 outputs the minimum voltage required by the second power supply unit 2. Therefore, heat generation from the entire power supply unit can be minimized at high temperatures, and the device can be operated stably even at high temperatures.

Embodiment One embodiment of the present invention will be described below with reference to FIGS. 2 to 5.

FIG. 2 shows a circuit diagram of an embodiment of the present invention. In FIG. 2, in the first power supply unit 1, the collector and emitter of the transistor Tr ₁ for power supply are provided on the DC voltage DC (+) line, and the switching regulator (hereinafter abbreviated as “SR”) at the base. ) 5, pulse current is intermittently supplied. The transistors Tr ₁ and SR 5 are characterized in that the heat loss amount hardly changes even if the voltage difference between the input and the output changes. The diode D ₁ , the choke coil L and the capacitor C are a smoothing circuit. The output voltage of the OP amplifier U ₁ is applied to SR5, and the voltage divided by the resistors R ₁ and R ₂ of the DC voltage DC (+) is applied to the positive input terminal of the OP amplifier U ₁ .

Further, in the second power supply unit 2, a transistor for supplying a constant voltage is provided on the output line of the DC voltage of the first power supply unit 1.
The collector and emitter of Tr ₂ are interposed between the load 3 and the base, and a dropper regulator (hereinafter abbreviated as “DR”) 6 supplies a control current to the base. This transistor Tr
₂ and DR6 are so-called series regulators in which the heat loss changes in direct proportion when the difference between the input voltage and the output voltage changes when the output current is constant. OP for DR6
The output voltage of amplifier U ₂ is applied. The voltage divided by the resistors R ₃ and R ₄ of the DC voltage output from the second power supply unit 2 is applied to the positive input terminal of the OP amplifier U ₂ , and the resistor R ₅ and the Zener diode are applied to the negative input terminal. A constant voltage due to D ₂ is applied. Then, the power is supplied from the second power supply unit 2 to the load 3.

In the sensor unit 4, the output signal from the temperature sensor 7 such as a thermistor installed in the electronic device is supplied to the DC amplifier 8
Is supplied to the base of the transistor Tr ₃ via. In addition, it is connected from the power supply Vcc to the base of transistor Tr ₃ via resistor R ₆ and also connected to transistor Tr ₃ via resistor R _7.
Connected to ₃ collectors. The emitter of the transistor Tr ₃ is grounded to the ground GND via the resistor R ₈ . Further, the collector output is applied to the negative input terminal of the OP amplifier U ₁ of the first power supply unit 1.

3 shows a specific circuit of SR5 of the first power supply unit 1. In SR5, the output of the OP amplifier U ₃ is supplied to the base of the transistor Tr ₁ . The positive input terminal of the OP amplifier U _3, voltage divided by the resistors R ₉ and R ₁₀ of the direct current voltage DC (+) is applied, the output voltage of the OP amplifier U ₁ is applied to the negative input terminal .

Next, the operation of the power supply device shown in FIGS. 2 and 3 will be described with reference to FIGS.

First, when the temperature T in the electronic device is equal to or higher than a certain value (the temperature rises after D [° C.] in FIG. 5 at which the device operates stably), the resistance value of the temperature sensor 7 decreases and , Transistor Tr ₃ is turned on. OP amplifier U
A collector output of voltage V ₂ is applied to the minus input terminal of ₁ (voltage V ₂ after D [° C.] in FIG. 5). Here, the resistance values of the resistors R ₁ and R ₂ are set so that a voltage having the same value as this voltage V ₂ is applied to the positive input terminal of the OP amplifier U ₁ , and the voltage V _{2 of the} negative input terminal is It becomes the reference value. Therefore, the output voltage of the OP amplifier U ₁ is zero. At this time, the point B of the DC voltage output line becomes the voltage V ₁ (Fig. 5D).
Voltage V ₁ ) after [° C].

In this case, the transistor Tr ₁ in the first power supply unit ₁
Switching is performed when the voltage at point B (Fig. 2) is high.
OP amplifier through the U ₁ OP amplifier U ₃ (FIG. 3) drives the transistor Tr ₁ in a narrow pulse current time width, A point (second
Decrease the DC voltage DC (+) in the figure). At this time, the voltage at the point B gradually decreases, and when the voltage at the point B reaches V ₁ , the operational amplifier U ₃ causes the transistor Tr ₁ to keep the voltage V ₁ after D [° C.] in FIG. 5 at a switching interval. Driven. As described above, due to the switching interval of the pulse current of the OP amplifier U _3, a pulse voltage having the switching interval is generated at the point A, and the point B becomes a smoothed DC voltage (V ₁ ) (D in FIG. 5). ° C] and subsequent voltage V ₁ ).

The voltage V _{1 at the} point B is the transistor of the second power supply unit 2.
The voltage is reduced to a voltage V ₃ (Fig. 5) by Tr ₂ and a predetermined electric power is supplied to the load 3, and the remaining difference due to the product of the voltage difference Vc (= V ₁ −V ₃ ) and the current flowing through the load 3 Power is transistor Tr
Heat loss occurs at ₂ and heat quantity Q [J] (Fig. 5D
It becomes the heat quantity Q) after [° C].

Here, the voltage at the resistors R ₃ and R ₄ that divides the voltage V ₃ and the resistor R ₅ and the Zener diode that generate the reference voltage.
The voltage due to D ₂ is connected to the positive input terminal and the negative input terminal of the OP amplifier U ₂ , respectively, and the differential output thereof is applied to DR 6. DR ₆ by supplying the base to the control voltage of the transistor Tr ₂ to the zero differential output of the OP amplifier U _2, transistor Tr ₂ is a constant regardless voltage V ₃ to the variation of the voltages V ₁ to the load 3 Supply.

Further, when the temperature exceeds a certain value, the transistor Tr ₃ becomes saturated and the voltage V ₂ becomes constant. Therefore, the voltage V ₁
Is also constant, the heat quantity Q [J] generated by the transistor Tr ₂ is also constant.

In this way, under high temperature, the first power supply unit 1 can be controlled so that the minimum voltage required by the second power supply unit 2 is output, and heat generation from the entire power supply unit can be minimized. Even under the condition, the device is stably operated.

The operating principles of the first power supply unit 1 and the second power supply unit 2 are the same even when the temperature inside the electronic device described below is below a certain value (under low temperature).

Next, when the temperature inside the electronic device falls below a certain value (at low temperature) according to the outside air temperature, the voltage V ₂ tends to increase as shown in FIG. Therefore, the temperature sensor 7 of the sensor unit 4
The low temperature value (in the case of a thermistor) becomes high, and the bias current to the transistor Tr ₃ decreases. As a result, the voltage V ₂ which is the output signal from the sensor unit 4 changes so as to increase. When the voltage V ₂ increases, the output voltage of the operational amplifier U ₁ of the first power supply unit 1 changes between D to C [° C.] in FIGS. Therefore, the output of the OP amplifier U ₃ (FIG. 3) biases the transistor Tr ₁ with a pulse current having a wide time width. This increases the emitter output of transistor Tr ₁
The voltage V ₁ is increased until the comparison of the input terminals of the P amplifier U ₁ becomes zero (voltage V ₁ between D to C [° C.] in FIG. 5). The increased voltage V ₁ is applied to the collector of the transistor Tr ₂ of the second power supply unit 2. In this case, DR6 is always a voltage V ₃ which biases transistor Tr ₂ to be constant voltage. Therefore, in the transistor Tr ₂ , the voltage difference VO (= V ₁ −
The power loss due to the product of V ₃ ) and the current flowing through load 3 is heat loss Q
Converted to [J]. Since the heat quantity Q is proportional to the voltage, if the voltage V ₂ is in proportion to the decrease of the external temperature in the period of D [° C] to C [° C] in Fig. 5, it increases linearly. Then, the output voltage V ₂ of the sensor unit 4 becomes constant because the transistor Tr ₃ is turned off in the temperature decrease before C [° C.] in FIG. Therefore, the voltage V ₁ also becomes constant, and the heat quantity Q [J] generated by the transistor Tr ₂ is generated.
Is also constant.

Here, for example, assuming that the DC voltage DC (+) is 24 [V], the efficiency of the transistor Tr ₁ is 80%, and the voltage applied to the load 3 and the flowing current are 5 [V] and 1 [A], respectively, When V ₁ is 6 [V] when the temperature inside the device is a certain value or more, the power loss of the transistor Tr ₂ is (6−5) × 1 = 1.
[W] and the power loss of transistor Tr ₁ is 6 [W]
X (1-0.8) = 1.2 [W]. Therefore, the total power loss in this temperature state is 2.2 [W]. On the other hand, when the temperature inside the device is below a certain value (low temperature), V ₁ is 20 [V]
, The power loss of the transistor Tr ₂ is (20-5)
× 1 = 15 [W], and the power loss of transistor Tr ₁ is 2
0 [W] x (1-0.8) = 4 [W]. Therefore, the total power loss in this temperature state is 24 [W]. The difference between the two is converted into a heat capacity Q [J], which is represented as in FIG. 5Q.

The heat quantity Q [J] in the transistors Tr ₁ and Tr ₂ raises the temperature in the electronic device. That is, even at low temperatures, the temperature inside the electronic device rises until the device can operate stably, which is particularly effective for electronic devices having mechanically movable parts.

Since the sensor unit 4 controls the amount of heat generated by the transistor Tr _{2 in} this manner, a separate heating device such as a heater can be omitted to raise the temperature inside the electronic device. As a result, a mounting space for a heater or the like becomes unnecessary, control noise of the heater or the like can be prevented, and a separate power source for the heater or the like can be dispensed with.

According to the present invention, the first power supply unit 1 changes the voltage applied to the second power supply unit 2 with respect to the temperature change, while the second power supply unit 2 includes the first power supply unit 1 The amount of heat generated by the transistor Tr ₂ is changed by changing the internal resistance of the transistor Tr ₂ in order to supply a constant voltage V ₃ to the load 3 regardless of the output voltage of the transistor Tr ₂ . The power supply unit 1 changes not only the voltage but also the current with respect to the temperature, and the second power supply unit 2 absorbs the change in the input voltage and the current and supplies a constant voltage to the load. Also has the same effect.

EFFECTS OF THE INVENTION As described above, according to the present invention, the second power supply unit is provided and the output power of the first power supply unit is changed according to the ambient temperature to control the heat loss, thereby heating the heater or the like. You can control the temperature inside the electronic device without using the device,
As a result, the device can be stably operated even in a wide range from high temperature to low temperature.

[Brief description of drawings]

FIG. 1 is a block diagram of the principle of the present invention, FIG. 2 is a circuit diagram showing an embodiment of the present invention, FIG. 3 is a circuit diagram showing a specific example of the switching regulator of FIG. 2, and FIG. Is a graph showing the change of the output voltage depending on the temperature condition, and FIG. 5 is a graph showing the amount of heat and the like in FIG. 1 ... 1st power supply part, 2 ... 2nd power supply part, 3 ... Load, 4 ...
Sensor part, 5 ... Switching regulator (SR), 6 ...
Dropper regulator (DR), 7 ... Temperature sensor.

Claims (1)

[Claims] 1. A sensor unit for changing an output signal according to an ambient temperature, and a unit for supplying electric power to a load, the ambient temperature being lower than a prescribed temperature according to the output signal of the sensor unit. A first power supply unit that sometimes changes the output power to a level larger than a specified power, and a first power supply unit that is interposed between the first power supply unit and the load, and outputs a predetermined amount of the output power from the first power supply unit. A second power supply unit that supplies electric power to the load and converts other electric power into heat loss, and a power supply device for electronic equipment.