JP7419867B2 - power supply - Google Patents

Description

The present invention relates to a power supply device.

2. Description of the Related Art In a power supply device, there is a known technique for controlling an inrush current prevention relay that switches between passing current through an inrush current prevention resistor arranged on the input side or short-circuiting the inrush current prevention resistor, depending on a detected value of input current.

The power supply device that controls such inrush current prevention relays includes a rectifier that rectifies the input AC voltage, a smoothing capacitor that smoothes the rectified voltage, a resistor that limits the inrush current that is input to the smoothing capacitor, and a current that flows through the resistor. The current detection circuit includes a relay for controlling whether to input or not, a current detection circuit, and a converter connected after the smoothing capacitor to adjust the voltage smoothed by the smoothing capacitor to a predetermined voltage. discloses a device that controls whether or not to enable a resistor depending on the flowing current (for example, Patent Document 1). In this device, when a current exceeding a predetermined value flows (when a short-circuit current is detected), the relay coil is turned off and the short-circuit current flows through a high-impedance resistor to protect the power supply device.

However, with the technology described in Patent Document 1, for example, when power is supplied by the wiring in a taut condition, or when the power capacity of indoor power supply equipment is insufficient, a short circuit occurs and a short circuit current flows. However, there is a problem in that the current does not flow up to the above-mentioned predetermined value, and the resistance that limits the rush current becomes ineffective, making it impossible to protect the power supply device.

The present invention has been made in view of the above, and an object of the present invention is to provide a power supply device that can protect the power supply device even when the supplied power is insufficient.

In order to solve the above-mentioned problems and achieve the objects, the present invention provides a rectifier for rectifying an AC voltage output from an AC power source into a DC voltage, an inductor connected to the output side of the rectifier, and an inductor connected to the output side of the rectifier. A first switching means arranged between the output ends of the rectifying means and installed on the downstream side of the inductor, and connected in parallel with the first switching means, smoothing the DC voltage output by the rectifying means. a smoothing means, a diode for preventing reverse current from flowing from the smoothing means to the first switching means, a current limiting means arranged in a path flowing from the first switching means to the rectifying means, and a current limiting means in parallel with the current limiting means. Voltage detection for detecting a voltage across a second switching means connected to the second switching means and the first switching means, and detecting a short-circuit time of the first switching means based on the detected voltage across the first switching means. and determining whether the short-circuit time detected by the voltage detection means is equal to or greater than a predetermined threshold, and when it is determined that the short-circuit time is equal to or greater than the threshold, the second switching means is opened. and a control means for correcting the threshold value in accordance with the voltage across both ends detected by the voltage detection means .

According to the present invention, the power supply device can be protected even when the supplied power is insufficient.

FIG. 1 is a diagram illustrating a case where sufficient current cannot be drawn into the power supply device during an abnormality. FIG. 2 is a diagram showing an example of the configuration of a conventional power supply device. FIG. 3 is a diagram showing fuse blowing characteristics. FIG. 4 is a diagram illustrating an example of the configuration of the power supply device according to the embodiment. FIG. 5 is a diagram showing an example of current and voltage states when a short circuit occurs. FIG. 6 is a diagram illustrating the operation of correcting the threshold value for determining the short circuit time.

Hereinafter, a power supply device according to the present invention will be described in detail with reference to the accompanying drawings. Furthermore, the present invention is not limited to the following embodiments, and the constituent elements in the following embodiments include those that can be easily figured out by a person skilled in the art, those that are substantially the same, and those that are within the so-called equivalent range. is included. Furthermore, various omissions, substitutions, changes, and combinations of constituent elements can be made without departing from the gist of the following embodiments.

(An example of a situation where sufficient current does not flow to the power supply during an abnormality)
FIG. 1 is a diagram illustrating a case where sufficient current cannot be drawn into the power supply device during an abnormality. With reference to FIG. 1, a case will be described in which a sufficient current cannot be drawn into the power supply device when a short circuit occurs.

In FIG. 1, power is supplied from an indoor power supply equipment 201 that supplies power to various indoor electronic devices to other electronic devices 211 and 212 and the power supply device 101 from the wiring that has been turned into an octopus by a power tap 202. Indicates a state in which In this case, since the power supply from the indoor power supply equipment 201 is distributed to each electronic device, there is a possibility that the power supply (power) supplied to the power supply device 101 becomes insufficient. Furthermore, if the power supply capacity of the indoor power supply equipment 201 itself is not sufficient, or if the power supply capacity is limited for some reason, there is a possibility that the power supply (power) supplied to the power supply device 101 will be insufficient. In such a case, if a short circuit occurs in the internal circuit of the power supply device 101 due to a foreign object, etc., a large short circuit current would normally flow, but even if a short circuit occurs, sufficient current can be drawn into the power supply device 101. A situation occurs where it is not possible to do so.

(About conventional power supply)
FIG. 2 is a diagram showing an example of the configuration of a conventional power supply device. FIG. 3 is a diagram showing fuse blowing characteristics. With reference to FIGS. 2 and 3, the configuration of the conventional power supply device 101 and problems in its protection operation will be described.

A conventional power supply device 101 shown in FIG. 2 is a power supply device that converts AC voltage to DC voltage and supplies DC power. The power supply device 101 includes an AC power supply 111, an input fuse 112, a diode bridge 113, an inrush current prevention resistor 114, an inrush current prevention relay 115, an inductor 116, a switching element 117, a diode 118, and a smoothing capacitor 119. and.

The AC power supply 111 is a power supply that supplies AC voltage. The input fuse 112 is an electronic component that is blown by Joule heat to protect the circuit when the current flowing from the AC power supply 111 becomes a large current exceeding a predetermined value. The diode bridge 113 is an electronic component that full-wave rectifies the AC voltage from the AC power supply 111 and converts it into a DC voltage.

The inrush current prevention resistor 114 is a resistor that protects the circuit by allowing current to flow through itself, which has a high impedance, when the current I based on the DC voltage rectified from the diode bridge 113 becomes excessive due to some reason (such as a short circuit). It is a vessel. The inrush current prevention relay 115 is a relay for switching between passing current through the inrush current prevention resistor 114 and short-circuiting both ends of the inrush current prevention resistor 114 under control by a control means 132 described later. Inrush current prevention relay 115 includes a switching element 115a and a coil 115b. The switching element 115a is a switching means that is opened and closed by turning on and off the coil 115b, and switches whether or not to short-circuit the inrush current prevention resistor 114. The coil 115b is an electronic component that is turned on and off under the control of the control means 132 to open and close the switching element 115a.

The inductor 116, the switching element 117, and the diode 118 constitute a PFC (Power Factor Correction) circuit (power factor correction circuit). ), and the opening/closing operation of the switching element 117 suppresses the generation of harmonic current and improves the power factor of the power supply device 101. The smoothing capacitor 119 is a capacitor that smoothes the DC voltage converted from the AC voltage by the diode bridge 113.

The power supply device 101 further includes a transformer 120, a switching element 121, a diode 122, a secondary smoothing capacitor 123, a capacitor 124, and a diode 125.

The transformer 120 has a primary winding 120a and a secondary winding 120b, and when a DC voltage is smoothed by a smoothing capacitor 119, an alternating current flows through the primary winding 120a as a switching element 121 opens and closes. The alternating current flowing through the primary winding 120a generates an alternating voltage in the secondary winding 120b according to the winding ratio of the transformer 120. The AC voltage generated in the secondary winding 120b is rectified by the diode 122 and smoothed by the secondary smoothing capacitor 123. Then, the voltage across the secondary smoothing capacitor 123 (DC voltage) becomes the output voltage of the power supply device 101.

Further, the transformer 120 has an auxiliary winding 120c, and when the switching element 121 opens and closes, a voltage is generated across the auxiliary winding 120c, current flows through the diode 125, and the capacitor 24 is charged. A DC voltage is generated from both ends of 24.

Power supply device 101 further includes current detection means 131 and control means 132.

The current detection means 131 is an electronic component that detects the value of the current I flowing into the diode bridge 113, and transmits the detected current value to the control means 132. The control means 132 is a control device that controls the operation of the rush current prevention relay 115 based on the current value detected by the current detection means 131. Specifically, when the control means 132 determines that the current value detected by the current detection means 131 is equal to or higher than a predetermined threshold value due to the occurrence of a short circuit current, etc., the control means 132 turns off the coil 115b of the inrush current prevention relay 115. to open the switching element 115a (non-conducting state) and allow the current I to flow through the rush current prevention resistor 114. As a result, an excessive short circuit current can be suppressed, and the power supply device 101 can be protected.

In the conventional power supply device 101 having the above configuration, when the power supplied by the AC power supply 111 is insufficient due to the state described above in FIG. 1, as shown in FIG. Let us consider a case where both ends are short-circuited due to a foreign object. In this case, as shown in FIG. 2, a short-circuit current flows in the direction of the arrow as current I due to the short circuit between both ends of the switching element 117, but since the power supplied by the AC power supply 111 is insufficient, the current detection means 131 The detected current value of the short circuit current may not reach the threshold determined by the control means 132 described above. In this case, the control means 132 determines that the current value detected by the current detection means 131 is less than the threshold value and is within the normal current value range, and turns the coil 115b of the inrush current prevention relay 115 on. As a result, the closed state (conductive state) of the switching element 115a is maintained. Then, the current I, which is a large short circuit current that does not reach the above-mentioned threshold value, does not flow through the rush current prevention resistor 114 and flows without being suppressed in magnitude. As shown in the fuse blowing characteristics of the input fuse 112 shown in FIG. (or the input fuse 112 does not blow), the operation to cut off the current flowing in the direction of the arrow in FIG. .

The configuration and operation of the power supply device 1 according to this embodiment for solving the above-mentioned problems with the conventional power supply device 101 will be explained with reference to FIGS. 4 to 6 below.

(Configuration of power supply device according to this embodiment)
FIG. 4 is a diagram illustrating an example of the configuration of the power supply device according to the embodiment. FIG. 5 is a diagram showing an example of current and voltage states when a short circuit occurs. The configuration and operation of the power supply device 1 according to this embodiment will be described with reference to FIGS. 4 and 5.

Like the power supply device 101, the power supply device 1 shown in FIG. 4 is a power supply device that converts AC voltage into DC voltage and supplies DC power. The power supply device 1 includes an AC power supply 11, an input fuse 12, a diode bridge 13 (an example of a rectifier), an inrush current prevention resistor 14 (an example of a current limiter), an inrush current prevention relay 15, and an inductor 16. , a switching element 17, a switching element 17 (first switching means), a diode 18, and a smoothing capacitor 19 (an example of a smoothing means). The rush current prevention relay 15 includes a switching element 15a (second switching means) and a coil 15b. Note that these components include the AC power supply 111, input fuse 112, diode bridge 113, inrush current prevention resistor 114, and inrush current prevention relay 115 (switching element 115a, coil 115b) of the power supply device 101 shown in FIG. 2, respectively. ), the inductor 116, the switching element 117, the diode 118, and the smoothing capacitor 119 have the same functions.

The power supply device 1 further includes a transformer 20, a switching element 21, a diode 22, a secondary smoothing capacitor 23, a capacitor 24, and a diode 25. The transformer 20 has a primary winding 20a, a secondary winding 20b, and an auxiliary winding 20c. Note that these components include the transformer 120 (primary winding 120a, secondary winding 120b, auxiliary winding 120c), switching element 121, diode 122, and secondary side of the power supply device 101 shown in FIG. 2, respectively. The function is similar to that of smoothing capacitor 123, capacitor 124, and diode 125.

The power supply device 1 further includes a voltage detection means 31 (an example of an operation detection means) and a control means 32. That is, the power supply device 1 includes a voltage detection means 31 instead of the current detection means 131 of the power supply device 101, and a control means 32 instead of the control means 132.

The voltage detection means 31 is an electronic component that detects the on/off operation of the switching element 17, as shown in FIG. Specifically, the voltage detection means 31 detects the voltage Vds that is the voltage across the switching element 17, and detects the voltage Vds as shown in FIG. The time when Vds is Low (hereinafter sometimes referred to as short-circuit time) is detected, and the detected short-circuit time is transmitted to the control means 32. The control means 32 is a control device that controls the operation of the inrush current prevention relay 15 based on the short circuit time of the switching element 17 measured by the voltage detection means 31. Specifically, the control means 32 determines whether the short circuit time detected by the voltage detection means 31 is equal to or greater than a predetermined threshold value, and if it is equal to or greater than the threshold value, the control means 32 determines whether or not the short circuit time detected by the voltage detection means 31 is equal to or greater than a predetermined threshold value. The coil 15b of the inrush current prevention relay 15 is turned off, the switching element 15a is opened (non-conductive), and the current I is caused to flow through the inrush current prevention resistor 14.

Thereby, an excessive short circuit current can be suppressed, and the power supply device 1 can be protected. In addition, since it is possible to detect a short-circuit state of the switching element 17 without depending on the current I, power can be supplied from the indoor power supply equipment (indoor power supply equipment 201, etc.) to the power supply 1 through the wiring that is in the octopus state. To protect the power supply device 1 even when a sufficient current cannot be drawn, such as when the indoor power supply equipment itself does not have sufficient power supply capacity, or when the power supply capacity is limited for some reason. I can do it.

Note that the rush current prevention resistor 14 may be, for example, a thermal fuse resistor. Thereby, even if the current I becomes a short-circuit current due to a short-circuit of the switching element 17, the internal fuse blows due to Joule heat and the circuit is cut off, so that the power supply device 1 can be more reliably protected.

Further, the opening/closing operation of the switching element 15a controlled by the control means 32 is performed by the on/off operation of the coil 15b, but the present invention is not limited to this. For example, the switching element 15a may be a switching element whose opening/closing operation can be controlled by a control signal. It may be used instead of.

(About correction of the threshold value used in the determination process of the control means)
FIG. 6 is a diagram illustrating the operation of correcting the threshold value for determining the short circuit time. Referring to FIG. 6, the operation of correcting the threshold value for short-circuit time determination in the control means 32 of the power supply device 1 according to the present embodiment will be described.

The inductor 16, switching element 17, and diode 18 shown in FIG. The generation of wave current is suppressed and the power factor of the power supply device 1 is improved. In this case, in the switching element 17, the duty ratio of the opening/closing operation varies depending on the magnitude of the input voltage (voltage Vds) that is the voltage across both ends. Specifically, as shown in FIG. 6(a), the switching element 17 has a duty such that the on time (closed state time, short circuit time) is short when the input voltage is high, and becomes long when the input voltage is low. Works with ratio. Therefore, the control means 32 needs to set the threshold value for determining the short circuit time detected by the voltage detection means 31 in accordance with the case where the input voltage is low and the ON time of the switching element 17 is long. For example, as shown in FIG. In the case of (a), it is necessary to set the threshold value to the detection time T1. However, if the threshold value is fixed to the detection time T1, even if the input voltage is high and the on-time is short, detection of a short circuit in the switching element 17 will be delayed.

Therefore, as shown in FIG. 6(b), when the input voltage is high and the on-time of the switching element 17 is short, the control means 32 sets the threshold to the detection time T2, for example, so that the on-time is long and the input voltage is high. The short circuit state of the switching element 17 can be detected earlier by T1-T2 than in the case of the threshold value (detection time T1) when the voltage is low. In this way, the control means 32 corrects the threshold for determining the short circuit time according to the magnitude of the input voltage (voltage Vds) detected by the voltage detection means 31. Thereby, the control means 32 can quickly detect the short circuit state of the switching element 17 by making a determination using an appropriate threshold value according to the operation of the switching element 17.

As described above, the power supply device 1 according to the present embodiment includes the inrush current prevention resistor 14 that limits current, the switching element 15a connected in parallel to the inrush current prevention resistor 14, and the switching element 15a included in the power factor correction circuit. A voltage detection means 31 detects the operation of the element 17, and determines whether or not a short circuit condition has occurred in the switching element 17 according to the operation of the switching element 17 detected by the voltage detection means 31, and determines whether a short circuit condition has occurred. In this case, the switching element 15a is opened. As a result, it is possible to detect a short-circuit state of the switching element 17 without depending on the current I, so that power is supplied from the indoor power supply equipment (indoor power supply equipment 201, etc.) to the power supply device 1 through the wiring that is in the octopus state. The power supply device 1 is protected even when it is unable to draw sufficient current, such as when the indoor power supply equipment itself does not have sufficient power supply capacity, or when the power supply capacity is limited for some reason. be able to.

1 Power supply device 11 AC power supply 12 Input fuse 13 Diode bridge 14 Inrush current prevention resistor 15 Inrush current prevention relay 15a Switching element 15b Coil 16 Inductor 17 Switching element 18 Diode 19 Smoothing capacitor 20 Transformer 20a Primary winding 20b Secondary winding 20c Auxiliary Winding 21 Switching element 22 Diode 23 Secondary smoothing capacitor 24 Capacitor 25 Diode 31 Voltage detection means 32 Control means 101 Power supply 111 AC power supply 112 Input fuse 113 Diode bridge 114 Inrush current prevention resistor 115 Inrush current prevention relay 115a Switching element 115b Coil 116 Inductor 117 Switching element 118 Diode 119 Smoothing capacitor 120 Transformer 120a Primary winding 120b Secondary winding 120c Auxiliary winding 121 Switching element 122 Diode 123 Secondary smoothing capacitor 124 Capacitor 125 Diode 131 Current detection means 132 Control means 201 Indoor Power supply equipment 202 Power strip 211, 212 Other electronic equipment

JP2019-004541A

Claims (2)

a rectifier for rectifying the AC voltage output from the AC power source into DC voltage;
an inductor connected to the output side of the rectifying means;
a first switching means disposed between the output ends of the rectifying means and installed on the downstream side of the inductor;
smoothing means connected in parallel with the first switching means and smoothing the DC voltage output by the rectification means;
a diode that prevents reverse current from flowing from the smoothing means to the first switching means;
current limiting means disposed in a path flowing from the first switching means to the rectifying means;
a second switching means connected in parallel with the current limiting means;
Voltage detection means for detecting a voltage across the first switching means and detecting a short-circuit time of the first switching means based on the detected voltage across the first switching means ;
Determining whether or not the short circuit time detected by the voltage detection means is equal to or greater than a predetermined threshold value, and if it is determined that the short circuit time is equal to or greater than the threshold value, control for opening the second switching means. means and
Equipped with
The control means is a power supply device that corrects the threshold value according to the voltage across both ends detected by the voltage detection means . The power supply device according to claim 1 , wherein the current limiting means is a thermal fuse resistor.

Images