JPH04334934A - Power source - Google Patents

Abstract

PURPOSE:To provide a switching circuit for switching power sources in a high efficiency without momentary power source interruption by using a plurality of selectors having different properties each in its proper way. CONSTITUTION:Auxiliary routes 18, 7, 9, 10 using, in addition to main routes 13, 14, 8 using relays, a diode and semiconductor switches, are employed, the main routes are normally used, and the auxiliary routes are used at the time of switching or a momentary power interruption. Since power sources can be switched with the configuration without using an auxiliary battery, subjects of resources, recovery can be avoided. Since the switching with high efficiency without momentary power source interruption is conducted, a using time with a battery having a limited capacity can be lengthened. Further, since the power sources can be selected without using a quasi-load, it is advantageous in volumetric and thermal manners.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device suitable for use in electronic devices.

0002

2. Description of the Related Art Devices such as personal computers that cannot be subject to instantaneous power interruptions require a power supply device that guarantees that there will be no instantaneous power interruptions.

[0003] Generally, the power source for these devices is as follows:
Commercial power or batteries are used. Portable laptop computers, computers that operate continuously for long periods of time, etc. have internal or external batteries and are equipped with power supplies that can be switched from commercial power sources.

[0004] Additionally, some laptop computers have multiple batteries. It has two removable batteries and a DC connector that inputs DC power from an AC adapter that supplies power converted from commercial power. supply to. This power supply has a function that allows you to switch the power supply while the main unit is operating. For example, if one battery is being used and the capacity of that battery is running low, it is possible to switch to the other battery. Also, if you disconnect the AC adapter while using it with the AC adapter, you can switch to supplying power from the battery. What is important in this case is that the power supply voltage must not be lowered below the specified voltage during switching, even for a short period of time. Of course, momentary interruptions are not allowed. For this reason, a means to switch between multiple power sources without instantaneous interruption is required.

A common method for switching between multiple power sources without momentary interruption is to use an auxiliary battery by float charging. This method is used by many computer manufacturers. A typical circuit using float charging is shown in Figure 2. This power supply circuit has a replaceable first battery 1 and a second battery 2, which are switched using a changeover switch 6. This switching is performed through a switching control signal 8. Input 7 from the AC adapter passes through diode 4 and reaches power supply line 9 to the main body. As can be seen from FIG. 2, the input from the AC adapter is connected to the auxiliary battery 3 through the current limiting resistor 12 at the power supply line 9. When the main body is in use, the voltage of the power supply line 9 to the main body has increased to a voltage at which the main body can be used, so the auxiliary battery 3 is charged through the diode 13. When there is no input 7 from the AC adapter, the output of either the first battery 1 or the second battery 2 is selected by the changeover switch 6 and output. At this time, when switching between batteries and switching between the AC adapter and the battery, a momentary power outage occurs, but at this time the output of the auxiliary battery 3 is output through the current limiting resistor 12,
Prevent instantaneous interruptions. The main battery selection device is
Relays are used, which are more efficient than semiconductor switches such as FETs.

On the other hand, as shown in FIG. 3, there is also a method of switching without using a battery by float charging. In this case, slow relays cannot be used to prevent momentary power outages, so semiconductor switches are used.

[0007] When switching to batteries, a means is needed to check which batteries are available. Since the open voltage and closed voltage of a NiCd battery, that is, the voltages differ between a loaded state and an unloaded state, the capacity of the battery cannot be determined from the voltage. Therefore, when it was necessary to measure the capacitance, the method used was to apply a pseudo load and measure the voltage.

[0008]

Although the float charging method is simple in terms of circuitry, it has the following drawbacks. First, NiCd batteries, which are common batteries used for float charging, contain cadmium, which is a hazardous substance, and therefore collection is required in some countries. Therefore, it takes time and effort for recovery. Furthermore, considering the lack of collection, there is also a problem from an environmental conservation standpoint.

[0009]Furthermore, the float-charged battery must always be located closest to the main body and must have a certain amount of capacity, so if it is built into the main body, the main body will be large. Furthermore, since the method of use of this battery is special, even though a certain amount of capacity is required, most of the capacity is not used and its life is exhausted, resulting in waste. Furthermore, this method of using the battery is not desirable for the battery, so it is necessary to select and design the battery more carefully than when using a normal battery. Otherwise, it may cause malfunctions such as leakage. Furthermore, it is difficult to establish a correspondence between the externally visible battery capacity and the actual capacity, which causes confusion for the user. This is because battery capacity varies greatly depending on usage conditions, so battery capacity during normal use and battery capacity during float charging are different even if the nominal capacity is the same. As described above, the method of using an auxiliary battery has many drawbacks, and a device is needed to switch between multiple power sources without using an auxiliary battery.

Furthermore, although it is desirable to use a selection device that is as efficient as possible, a high switching speed is required in order to switch without momentary interruption. Relays were efficient but slow, so they could not be used without an auxiliary battery, and inefficient semiconductor switches were used instead.

[0011] Furthermore, the method of using a pseudo load as a means of obtaining battery capacity has disadvantages in terms of volume and heat since it is necessary to provide a pseudo load.

An object of the present invention is to provide a means for switching between multiple power sources without using an auxiliary battery.

Another object of the present invention is to provide a method for switching between a plurality of power sources without momentary interruption without using an auxiliary battery.

Still another object of the present invention is to provide an efficient,
Moreover, it is an object of the present invention to provide a switching device without momentary interruption.

Still another object of the present invention is to provide an apparatus for checking which power sources are available during switching.

[0016]

SUMMARY OF THE INVENTION The present invention has a plurality of power source selection devices and switches the power source without using an auxiliary battery. Furthermore, the present invention provides a switching device that is efficient and does not cause instantaneous interruptions. Further, in order to check which batteries can be used, a current detection device is provided in all or part of the selection device, and the power source is selected based on the output thereof.

[0017]

[Operation] Since the power source can be switched without using an auxiliary battery, resource problems and collection problems can be avoided. Furthermore, since switching can be performed efficiently and without momentary interruptions, the usage time of a battery with limited capacity can be extended. In addition, since the power source can be selected without using a dummy load, it is advantageous in terms of volume and heat.

[0018]

[Embodiment] An embodiment of the present invention will be explained with reference to the drawings. Figure 1
is a configuration diagram of the present invention. In FIG. 1, the main route changeover switch 6 uses a relay. Also,
The auxiliary route switch uses a field effect transistor. As the current detection means, a method is adopted in which a voltage drop due to the current flowing through the resistor 19 is detected by a comparator 20.

First, charging will be explained. When charging, first flip the main route changeover switch 6 toward the battery you want to charge. When it is desired to charge the first battery 1, the main route changeover switch 6 is connected to the first battery 1 side using the main route control signal 8, and a voltage is applied to the input 11 from the AC adapter. By doing so, a circuit is created that runs from the input 11 through the switch 6 and through 14 to the first battery 1, and the first battery 1 can be charged. To charge the second battery 2, the main route changeover switch 6 may be connected to the second battery 2 side, and voltage may be applied to the input 11 from the AC adapter.

Next, discharge will be explained. When the input from the AC adapter is normal, the output 12 to the main unit is
Input 11 from the adapter is directly output through diode 3. Here, in order to avoid the influence of momentary interruption of the input from the AC adapter, the first auxiliary route switch 7 and the second auxiliary route switch 18 are kept in a conductive state. Since there are diodes 9 and 10 on each auxiliary route, by setting the output from the AC adapter higher than the voltage of batteries 1 and 2, the AC adapter normally does not use battery power or charge. Only when the output of the battery becomes abnormal, the battery 1 or 2 is
of power is provided as output 12 to the body. It is determined whether the output is from the first battery 1 or the second battery 2. The higher voltage is output first.

Next, discharging by the battery will be explained. For battery discharge, input 1 from the AC adapter
This is done when there is no 1. When supplying the output from the first battery 1, the main route changeover switch 6 is operated to make the first battery 1 conductive. In this state, when the power of the first battery 1 is consumed and it is determined that it is insufficient to drive the main body, the power is switched to the second battery 2. The changeover switch 6 in the main route is
Relays are used in consideration of efficiency, but relays usually require a switching time of 10 to several tens of milliseconds. Therefore, in order to prevent instantaneous power outage at this time, first the auxiliary route switch 18 of the second battery 2 is made conductive using the second auxiliary route switch control line 17. Second auxiliary route switch 1
No. 8 uses a field effect transistor, so switching can be performed at a very high speed. The speed is generally said to be several nanoseconds. Furthermore, since the second auxiliary route switch is a semiconductor switch, there is no bounce or chattering, making it easy to control. After this, the second battery 2 can be used by moving the main route changeover switch 6 to the second battery 2 side. When switching from the second battery 2 to the first battery 1, the switching can be performed in the same manner without momentary interruption.

The same principle can be used to ensure safety when attempting to remove a battery while it is in use. To do this, when you try to remove the battery,
Provide a means to detect this. A typical example is a lock pin that must be moved when removing the battery pack. A sensor such as a microswitch is attached to this, and a device is created so that the sensor reacts before the battery terminal is completely separated. This reaction time needs to be at least several milliseconds before the terminals of the battery start to separate. However, this does not require any special mechanism considering the speed of human hands. In response to the signal from the sensor, the second auxiliary route switch 18 is made conductive. The speed during this time is several nanoseconds, which is the speed of the switch, so
It's fast enough. After that, the main route changeover switch 6 may be switched. By doing so, it is possible to prevent instantaneous power outage even if the battery is removed inadvertently.

Next, the effects of the current detection circuit will be explained. If the first battery 1 and the second battery 2 are replaceable, it is difficult to know the capacity of the newly installed battery. This is because the no-load voltage has an extremely weak correlation with the voltage during actual use. The present invention attempts to take measures to at least prevent instantaneous power outages without having to measure the battery voltage using a pseudo load in advance.

Consider the case where the main body is powered on after the first battery 1 and second battery 2 are newly installed. At this time, if there is input 11 from the AC adapter, the main body operates on AC power even though the states of the two batteries are unknown. When the AC adapter is disconnected, the power is switched to the battery in order to prevent momentary power outages, and the method for doing so will be explained. First, when AC drive is performed, the battery is always in a conductive state, and as long as at least one of the batteries has power remaining, instantaneous power outages can be prevented. Afterwards, decide which battery to use. When a current flows through the second auxiliary route, the current flows through the resistor 19 and causes a voltage drop, which is detected by the comparator 20. This indicates that the power of the second battery 2 is superior to the power of the first battery 1. Therefore, in this case, since it is necessary to switch to the second battery, it is sufficient to turn off the first auxiliary route switch 7 after flipping the main route changeover switch 6 to the second battery side. If the output 5 of the current detection device is not detected, the first battery 1 has more power, so
The main route is placed on the first battery 1 side, and the second auxiliary route is cut off. When disconnecting the auxiliary route, it is necessary to provide a sufficient time lag in consideration of the time required to switch the main route changeover switch 6 and the time from switching to stabilization.

The current detection device in FIG. 1 is composed of a current detection resistor 19 and a comparator 20. As can be seen from FIG. 1, the power supply for the comparator 20 is supplied from the second auxiliary route. It is created based on the output, and will not operate unless the second auxiliary route is in a conductive state and the second battery 2 has a certain amount of power. Therefore, the structure is such that power is consumed only when it is really necessary, achieving low power consumption.

[0026]

As described above, according to the present invention, a power supply device can be made small and safe.

[Brief explanation of drawings]

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

FIG. 2 is a circuit diagram showing a conventional general battery drive circuit using float charging.

FIG. 3 is a circuit diagram showing a conventional general battery drive circuit using a semiconductor switch.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1...First battery, 2...Second battery, 3...Diode, 4...Control signal of first auxiliary route, 5...Output of current detection circuit, 6...Main route changeover switch, 7...First auxiliary route switch, 8 ...Control signal of main route changeover switch, 9...First auxiliary route diode, 10...Second auxiliary route diode, 11...Input from AC adapter, 12...Power output to main unit, 13...Output of second battery, 14 ...output of the first battery, 15...output after selecting the first auxiliary route, 16...output after selecting the second auxiliary route, 1
7... Control signal for second auxiliary route, 18... Second auxiliary route switch, 19... Resistor for current detection, 20... Comparator for current detection, 21... First detection voltage for second auxiliary route, 2
2... Output before selection of second auxiliary route, 23... Output before selection of first auxiliary route

Claims (12)

[Claims] 1. A power supply device comprising a plurality of batteries and a selection device for selecting one of these batteries and connecting it to a main body, and characterized in that there are a plurality of selection devices. 2. A power supply device comprising a plurality of power supplies and a selection device for selecting one of the power supplies and connecting it to the main body, and comprising a plurality of selection devices. 3. A power supply device comprising a plurality of power supplies, a plurality of batteries, and a selection device that selects one of these and connects it to the main body, and has a plurality of selection devices. 4. The power supply device according to claim 1, wherein a part of the selection device includes a current detection device. 5. The power supply device according to claim 1, wherein all of the selection devices are provided with a current detection device. 6. The power supply device according to claim 4, wherein the current to be detected is used as a power source for the current detection device. 7. The power supply device according to claim 4, further comprising a selection device equipped with a rectifier. 8. The power supply device according to claim 7, further comprising a current detection device between the selection device and the rectification device. 9. A power supply device comprising a rectifier on the side closer to the main body and a selection device on the side closer to the power source or battery. 10. The power supply device according to claim 7, 8, or 9, wherein a selection device equipped with a rectifier is connected when a commercial power source is used. 11. In switching the power source to be selected, a selection device equipped with a rectifier is connected to the power source currently in use,
10. The power supply device according to claim 7, wherein the main selection device is then switched from connection with the power supply currently in use to connection with a power supply to be used next. 12. In selecting a power source, a selection device equipped with a rectification device selects all the power supplies, and when a current detection device provided in the selection device equipped with a rectification device detects a current, the detected current Claim 10 or Claim 11, wherein a power supply equipped with a detection device is selected, and if not, a power supply not equipped with a current detection device is selected.
Power supply listed.