JP2015192301A - Power supply device and power supply method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the influence of a transient phenomenon during switching, by reducing a switching time when the voltage of a power source decreases below the voltage of a battery and the power source is switched.SOLUTION: A power supply device includes: a first power source that supplies power to a load; a first semiconductor element that controls output from the first power source; a first control section that controls the first semiconductor element; a second power source that provides back up for the first power source; a second semiconductor element that controls output from the second power source; and a second control section that controls the second semiconductor element. The power supply device comprises: a voltage detecting section that detects a voltage decrease in the first power source. The second control section has a current detection control section that controls the second semiconductor element.

Description

  The present invention relates to a power supply device using an ORing FET, and more particularly to improvement of the power supply device.

  In recent years, energy saving of devices has progressed, and in the high-end field, power consumption tends to increase as performance increases. In the field of electronic equipment called weak electricity, it is not rare to handle kilowatt-class power. In the case of providing redundancy to a power supply device that handles such a load, the need for an ORing FET is increasing because the ORing diode generates too much heat.

  For example, when the power supplies are connected in parallel, it is easy to connect the plurality of power supplies 11 and 13 to the load 15 via the ORing diodes 12 and 14 as shown in FIG. However, due to the characteristics of the diode, if the current consumption on the load 15 side increases, the power consumption of the diode itself also increases. Therefore, an FET and its control circuit may be placed instead of the diode. For example, if the device has a power supply voltage of 12v and a power consumption of 360w, the current is 30A. Therefore, even if a Schottky barrier diode (forward voltage: 0.4v) is used as the diode, 0.4v * 30A = 12w Is consumed by the diode itself. On the other hand, if this is replaced with a FET (on-resistance at saturation: 1 mΩ), only 1 mΩ * (30A) * (30A) = 0.9 w of power is consumed by the FET itself, and a large reduction effect is obtained. Can do.

  FIG. 5 shows a circuit configuration of the ORing FET compared with the circuit of the ORing diode of FIG. A combination of the FET 22 and the FET control unit 26 functions as an ORing FET. The FET 22 has a source (S) terminal 221, a drain (D) terminal 222, and a gate (G) terminal 223. The control operation will be described in comparison with FIG. The diode operation of FIG. 4 conducts when the voltage is higher at the cathode terminal than at the anode terminal, and does not conduct when the voltage is reversed (exactly, the anode terminal is applied with a forward voltage [Vf] or more than the cathode terminal). If conductive).

  The FET controller 26 performs the following control so that the same movement is performed in FIG. That is, in order to virtually function the S terminal 221 as the anode of the diode and the D terminal 222 as the cathode of the diode, the voltage of the S terminal 221 and the D terminal 222 is monitored by the comparator 261. Since the D terminals of the FET 22 and the FET 24 are connected to each other, the voltage at the D terminal of the FET 24, that is, the voltage obtained by subtracting the voltage applied between the SD terminals of the FET 24 from the output voltage of the power source 23 is applied to the D terminal 222. When the output voltage of the power source 23 decreases for some reason such as a failure and the voltage at the D terminal 222 falls below the voltage at the S terminal 221, the gate drive unit 262 drives the G terminal 223 to turn on the FET 22 and make it conductive. Conversely, when the voltage at the D terminal 222 exceeds the voltage at the S terminal 221, the gate drive unit 262 drives the G terminal 223, turns off the FET 223, and stops conduction.

  FIG. 6 shows a circuit in which one of the power sources in FIG. 5 is replaced with a battery 31 (in a storage device, a battery is stored so that data stored in the cache is not lost even when the power supply is suddenly cut off due to a power failure or the like. Is usually installed). Usually, since it operates with AC power supply, the output voltage of the battery 31 is set lower than the output voltage of the power supply 33. The expected operation of this circuit is that the power supply 33 voltage (for example, 12v) is abruptly lowered due to a power failure or the like, and automatically switches to battery power supply when the voltage is lower than the battery 32 voltage (for example, 10v).

  When the power supply 33 voltage suddenly drops below the voltage of the battery 31 at the time of a power failure or the like, the comparator 361 of the FET control unit 36 has a D terminal 322 (virtual cathode terminal) rather than an S terminal 321 (virtual anode terminal) of the FET 32. Is detected and transmitted to the gate driver 362, and the gate driver 362 drives the G terminal 323. The drive of the G terminal 323 usually gives a voltage about 5v higher than that of the S terminal 321, so in the case of the aforementioned 10v battery output, it must be driven from 0v to 15v. Therefore, a time difference from when the voltage of the power source 33 actually falls below the voltage of the battery 31 until detection and driving occurs.

  For example, when the ORing FET control IC is TI TPS2410 and the ORing FET is IRFH5250, the detection time is approximately 25 us and the driving time is 500 us. That is, even if the voltage of the power source 33 is lower than the voltage of the battery 31, power is not supplied from the battery 31 for 500 us. Although depending on the value of the load current of the device, the voltage of the power supply 33 may suddenly drop during that time. In some cases, it is possible that the voltage drops below the operating voltage due to this decrease, and the system goes down without switching to battery operation even though the battery 31 is connected. In the case of an ORing diode as shown in FIG. 4, the diode turn-on time corresponds to this time difference, but in general, considering that the diode turn-on time is several ns, such time difference should be ignored. Can do.

  On the other hand, when the power is shut down due to a power failure or the like, the large load is moved only by the charge stored in the internal capacitor until the battery is switched to power supply. Become. If the charge capacity provided in the circuit is insufficient, the battery may not function at all.

  As the above related technology, Patent Document 1 supplies power to a main body from a lithium polymer battery in a normal operation, and when a current exceeding a certain level is required, the main battery such as a lithium ion battery supplies insufficient power. I am trying to supply.

JP 2001-268814 A

  However, Patent Document 1 does not consider shortening the switching time.

  An object of the present invention is to take this point into consideration, and is to shorten the switching time when the power supply voltage is lower than the battery voltage and the power supply is switched.

In the present invention, in order to solve the above-described problem, a first power source that supplies power to a load, a first semiconductor element that controls output of the first power source, and a first power source that controls the first semiconductor element. , A second power source that backs up the first power source, a second semiconductor element that controls the output of the second power source, and a second control unit that controls the second semiconductor element. In the power supply device,
A voltage detection unit that detects a voltage drop of the first power supply and controls the second power supply based on the detection result, and a second control unit includes a current detection control unit that controls the second semiconductor element. It is characterized by that.

  In the present invention, in order to solve the above problem, a first power source for supplying power to a load, a first semiconductor element for controlling an output of the first power source, and a first semiconductor element are controlled. A first control unit; a second power source for backing up the first power source; a second semiconductor element for controlling an output of the second power source; and a third semiconductor element for controlling an output of the second power source And a second control unit that controls the second semiconductor element and the third semiconductor element, wherein the second control unit includes the second semiconductor element and the third semiconductor element. It is characterized by having a current detection control unit for controlling.

  According to the present invention, when the power supply voltage is lower than the battery voltage and the power supply is switched, the switching time can be shortened.

It is a block diagram which shows the structure of the power supply device in the 1st Embodiment of this invention. It is a timing chart explaining operation | movement of the power supply apparatus in the 1st Embodiment of this invention. It is a block diagram which shows the structure of the power supply apparatus in the 2nd Embodiment of this invention. It is a block diagram which shows the structure of the power supply apparatus of the related technology of this invention. It is a block diagram which shows the structure of the power supply apparatus of the related technology of this invention. It is a block diagram which shows the structure of the power supply apparatus of the related technology of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(First embodiment)
The configuration of the power supply device of this embodiment will be described with reference to FIG. FIG. 1 is a block diagram illustrating a configuration example of a power supply device according to the first embodiment of the present invention. 1 is different from FIG. 5 in that the FET control unit 46 includes a current detection control unit 463 and a voltage drop detection unit 47 that is connected to the battery 41 and detects a voltage drop of the power supply 43. It is a point. The current detection control unit 463 is connected to the line connecting the battery 41 and the source terminal 421 of the ORing FET 42 and the gate driving unit 462. The voltage drop detection unit 47 is connected to the output terminals of the power supply 43 and the battery 41.

  When the voltage of the power supply 43 decreases due to a power failure, failure, or the like, the voltage decrease detection unit 47 outputs a discharge signal 48 to the battery 41, and the battery 41 starts current output. When the discharge signal 48 is input, the battery 41 starts to supply power.

  The current detection control unit 463 of the FET control unit 46 detects the current when the current flows from the battery 41 or the FET 42.

  The operation of this embodiment will be described with reference to FIGS.

  FIG. 2 is a timing chart showing the time change of the voltage of the target block in FIGS. 1 and 6. In FIG. 2, V (423) indicates the time change of the voltage of the gate 423 of the FET 42, V (422) indicates the time change of the voltage of the drain 422 of the FET 42, and V (322) indicates the FET 32 of FIG. The time change of the voltage of the drain 322 is shown.

  In normal times, the power supply 43 is normally supplied. At this time, since the terminal voltage of the ORing FET 42 on the battery 41 side is higher at the D terminal 422 than at the S terminal 421, the FET 42 must be turned off. In the background art, the G terminal 423 is set to 0 v in order to turn off the FET 42. However, in the present embodiment, in FIG. 1, the voltage is controlled by the current detection control unit 463 to increase the voltage at the G terminal 423 to increase the state of the FET 42 from the completely off state to the state just before the on state. Here, the G terminal 423 of the FET 42 is raised to about 12v. This is to enable the FET 42 to be immediately turned on when the voltage is supplied to the G terminal 423 from the gate driving unit 462.

  Although this state is maintained during normal operation, a case will be described where some abnormality occurs and the voltage of the power supply 43 drops rapidly and switches to the battery 42 voltage.

  When the voltage of the power supply 43 drops due to a power failure, failure, etc. (t1), the G terminal of the FET 42 is capacitively coupled with the D terminal and the gate insulating film, and therefore the G terminal decreases accordingly when the D terminal voltage decreases. The voltage V423 at the G terminal 423 also drops.

As soon as the voltage of the power supply 43 starts to drop, a discharge signal 48 is output from the voltage detection means 47 to the battery 43, and battery output starts. Here, the current detection control unit 463 controls the output voltage of the gate drive unit 462 so that the voltage of the battery 41 is maintained at about + 2v. Thereafter, the voltage of the power supply 43 continues to decrease, and eventually the D terminal 422 becomes lower than the S terminal 421. Then, regardless of the result of the current detection control unit 463, the gate drive unit 462 drives the G terminal 423 and starts an operation as a normal ORing FET (t3). That is, the voltage of the battery 41 is applied to the load 45 via the FET 42. Immediately before the switching (t2), if the voltage of the battery 41 is about 10v, the voltage at the G terminal 423 is about 12v. It will suffice (V2-V1). In the description of FIG. 6, when it takes t5-t3 (for example, 500 us) to drive the gate driving unit 362 from 0 v to 15 v, this can be shortened to t4-t3 (for example, about 100 us). .
(Second Embodiment)
A second embodiment of the present invention will be described with reference to FIG. FIG. 3 is a block diagram showing the configuration of the second embodiment.

  As shown in FIG. 3, an FET 57 is added and arranged back to back with the existing FET 52. Specifically, the FETs 52 and 57 connect the S terminals. The G terminals of the two FETs are both connected to the gate drive unit of the FET control unit 56. Further, the D terminal of the FET 52 is connected to the D terminal of the FET 54, and the D terminal of the FET 57 is connected to the current detection unit. 1 except that an FET 57 is added.

  In the circuit of FIG. 3, the voltage on both sides of the FET 52 and the FET 57 can be blocked. That is, even when a constant output type battery is used, this embodiment can be applied, and the voltage drop detection unit 47 of FIG. 4 can be dispensed with.

  As described above, according to the embodiment of the present invention, when the power source voltage is lower than the battery voltage and the power source is switched, the switching time is shortened to reduce the influence of the transient phenomenon at the time of switching. can do.

  The present invention is not limited to the above-described embodiment, and can be implemented with various changes and modifications without departing from the gist of the present invention.

  The present invention can be applied to a power supply device that uses an ORing FET to provide redundancy to a power supply device that supplies power to a load.

11, 13, 21, 23, 33, 43, 53 Power supply 12, 14 Diode 15, 25, 35, 45, 55 Load 22, 24, 32, 34, 42, 44, 52, 54, 57 FET
26, 29, 36, 39, 46, 49, 56, 59 FET control unit 31, 41, 51 Battery 47 Voltage drop detection unit 48 Voltage drop detection unit 221 S terminal 222 D terminal 223 G terminal 261 Comparator 262 Gate drive unit 321 S terminal 322 D terminal 323 G terminal 361 Comparator 362 Gate drive unit 421 S terminal 422 D terminal 423 G terminal 461 Comparator 462 Gate drive unit 463 Current detection control unit

Claims (8)

A first power source for supplying power to the load;
A first semiconductor element for controlling an output of the first power source;
A first control unit for controlling the first semiconductor element;
A second power source for backing up the first power source;
A second semiconductor element for controlling the output of the second power source;
A power supply device comprising a second control unit for controlling the second semiconductor element;
A voltage detection unit that detects a voltage drop of the first power supply and controls the second power supply based on a detection result;
The second control unit controls a current detection control unit that controls the second semiconductor element;
A power supply device comprising:   The second control unit controls the second semiconductor element to conduct when the output voltage of the first power supply is lower than the output voltage of the second power supply. The power supply device described in 1.   4. The power supply device according to claim 1, wherein the voltage detection unit detects a decrease in the voltage of the first power supply and sends a signal for starting output of the second power supply. 5.   During normal operation, the current detection control unit applies a slightly lower voltage to the control terminal of the second semiconductor element than when the second semiconductor element is turned on, and outputs the voltage to the second control unit. The power supply device according to claim 1, wherein the current is controlled.   5. The power supply device according to claim 1, wherein the second power source is a battery whose output is controlled by a signal from the voltage detection unit. 6.   6. The power supply apparatus according to claim 1, wherein the first and second semiconductor elements are field effect transistors. A first power source for supplying power to the load;
A first semiconductor element for controlling an output of the first power source;
A first control unit for controlling the first semiconductor element;
A second power source for backing up the first power source;
A second semiconductor element for controlling the output of the second power source;
A third semiconductor element for controlling the output of the second power source;
In a power supply apparatus comprising a second control unit that controls the second semiconductor element and the third semiconductor element,
The power supply apparatus, wherein the second control unit includes a current detection control unit that controls the second semiconductor element and the third semiconductor element.   8. The power supply device according to claim 7, wherein the second semiconductor element and the third semiconductor element are field effect transistors in which control terminals are connected to each other and one current terminal is connected to each other. .

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