Power supply device

Abstract

In two power supply units operating in redundancy, the instantaneous voltage drop when one power supply unit stops is suppressed, and the stop of the drive device caused by the voltage drop is avoided. A power supply device (1) includes two power supply units (10) each comprising a voltage conversion circuit (11) having a switching circuit (15) outputting an output voltage corresponding to an input voltage, and a PWM control circuit (16) controlling the on / off operation of the switching circuit based on the output voltage to stabilize the output voltage; a voltage correction circuit (12) boosting the output voltage only when the input voltage is lower than a predetermined voltage, and two power supply units drive a load device (30) using a drive voltage obtained by connecting the output voltages output from the output terminals in parallel, and when the input voltage of one of the two power supply units decreases, the other power supply unit restores the decreased drive voltage to a predetermined voltage.

Description

Technical Field

[0001] This invention relates to power supply devices, and more particularly to power supply devices that connect multiple switching power supply units using PWM control in parallel for redundant operation. Background Technology

[0002] As a power conversion device that converts the input voltage to the desired voltage and outputs it, it is well known that switching power supply units utilize PWM (Pulse Width Modulation) control to stabilize the output voltage. In recent years, in order to improve the power supply reliability of systems such as critical servers and medical equipment that cannot be shut down, power supply devices that connect multiple switching power supply units in parallel for redundant operation and provide a specified power are used so that power supply does not stop even if a specific power supply unit stops.

[0003] In this redundant operation mode, multiple power supply units share the power required by the load device. Therefore, even if some of the power supply units stop, the required power supply can be maintained by increasing the output power from the other power supply units, and the operation of the load device driven by that output voltage can continue continuously. However, since the switching power supply unit using PWM control only increases the output power sequentially after detecting a decrease in output voltage, a certain time delay occurs from the detection of the voltage decrease to the increase in output power.

[0004] Therefore, even with redundant operation, a momentary voltage drop can occur when some power supply units stop and the output voltage of other power supply units increases to restore the specified power supply. If this voltage drop is large, there is a risk that the driven load devices may stop. Summary of the Invention

[0005] The technical problem that the invention aims to solve

[0006] This disclosure was made in view of the following problem, and its object is to provide a power supply device that, in a power supply device in which multiple power supply units are connected in parallel for redundant operation, suppresses the instantaneous voltage drop when some power supply units stop, and avoids the shutdown of the load device due to the voltage drop.

[0007] Technical means for solving technical problems

[0008] One aspect of the power supply device of the present invention is characterized by comprising two power supply units, each power supply unit including: a voltage conversion circuit having a switching circuit and a PWM control circuit, the switching circuit outputting an output voltage corresponding to the input voltage, and the PWM control circuit controlling the switching circuit to turn on / off according to the output voltage to stabilize the output voltage; a voltage correction circuit boosting the output voltage only when the input voltage is lower than a predetermined voltage; an input terminal; and an output terminal, the input terminals of the two power supply units being electrically insulated from each other, the two power supply units driving a load device using a drive voltage formed by connecting the output voltages output from their respective output terminals in parallel, and when the input voltage of one of the two power supply units decreases, the drive voltage is detected to decrease along with the decrease in the input voltage, and the other power supply unit restores the decreased drive voltage to a predetermined voltage.

[0009] Invention Effects

[0010] According to the power supply device disclosed herein, a power supply device can be provided that, in a power supply device in which multiple power supply units are connected in parallel for redundant operation, suppresses the instantaneous voltage drop when some power supply units stop, thereby avoiding the shutdown of the load device due to the voltage drop. Attached Figure Description

[0011] Figure 1 This is a circuit block diagram of the first embodiment of the power supply device.

[0012] Figure 2 yes Figure 1 A detailed circuit diagram of the first embodiment of the power supply device.

[0013] Figure 3A This is a timing diagram of the input to a power supply unit being cut off in a power supply device without a voltage correction circuit.

[0014] Figure 3B This is a timing diagram in the first embodiment of the power supply device when the input to a power supply unit is cut off.

[0015] Figure 4A This is a timing diagram for restarting a power supply unit in a power supply device without a voltage correction circuit.

[0016] Figure 4B This is a timing diagram of restarting a power supply unit in the first embodiment of the power supply device.

[0017] Figure 5 yes Figure 2 A variation of the detailed circuit diagram of the first embodiment of the power supply device.

[0018] Figure 6 This is a circuit block diagram of the second embodiment of the power supply device.

[0019] Figure 7 yes Figure 6 A detailed circuit diagram of the second embodiment of the power supply device.

[0020] Figure 8 yes Figure 7 A variation of the detailed circuit diagram of the second embodiment of the power supply device. Detailed Implementation

[0021] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0022] <First Implementation Method>

[0023] Figure 1 The diagram shows a circuit block diagram of a first embodiment of the power supply device 1. The power supply device 1 includes two power supply units 10 and 20. One power supply unit 10 includes a voltage conversion circuit 11, a voltage correction circuit 12 connected in parallel with the voltage conversion circuit 11, an input terminal 13, and an output terminal 14.

[0024] The voltage conversion circuit 11 includes a switching circuit 15 and a PWM control circuit 16. The switching circuit 15, controlled by PWM (Pulse Width Modulation), outputs a converted voltage VoA1 based on the input voltage Vin1 supplied from the input terminal 13. The switching circuit 15 performs high-speed switching at a fixed period, repeatedly turning the input voltage Vin1 on and off. The converted voltage VoA1 can then be adjusted by increasing or decreasing the on-time within this fixed period, i.e., changing the on / off ratio (duty cycle).

[0025] The PWM control circuit 16 controls the switching circuit 15 to turn on / off based on the switching voltage VoA1 of the switching circuit 15, thereby stabilizing the switching voltage VoA1. The PWM control circuit 16 monitors the switching voltage VoA1 of the switching circuit 15 and sends a control signal corresponding to the switching voltage VoA1 to the switching circuit 15.

[0026] For example, when the conversion voltage VoA1 is higher than the specified voltage, a signal is sent to reduce the on / off ratio of the switching element (shorten the on-time). The switching circuit 15 receives this signal and reduces the conversion voltage VoA1 by shortening the on-time of the switching element. Conversely, when the conversion voltage VoA1 is lower than the specified voltage, a signal is sent to increase the on / off ratio of the switching element (lengthen the on-time). The switching circuit 15 receives this signal and increases the conversion voltage VoA1 by extending the on-time of the switching element. The conversion voltage VoA1 is output as the output voltage VoK1 from the output terminal 14 via the series-connected diode element 17.

[0027] The voltage correction circuit 12 has the following function: it continuously monitors the input voltage Vin1 input to the voltage conversion circuit 11, and only boosts the conversion voltage VoA1 when the input voltage Vin1 input to the voltage conversion circuit 11 is lower than a predetermined voltage. When the voltage correction circuit 12 detects a decrease in the input voltage Vin1 by detecting an input voltage Vin1 lower than the predetermined voltage, it sends a signal to the PWM control circuit 16 to increase the on / off ratio of the switching element. Upon receiving the signal from the voltage correction circuit 12, the PWM control circuit 16 sends a signal to the switching circuit 15 to further increase the on / off ratio compared to the on / off ratio of the switching element determined according to the conversion voltage VoA1 of the switching circuit 15. This further boosts the conversion voltage VoA1. Furthermore, the voltage correction circuit 12 does not perform this operation when no input voltage Vin1 lower than the predetermined voltage is detected.

[0028] Another power supply unit 20 also has the same circuit structure and performs the same circuit operation as one power supply unit 10. That is, the other power supply unit 20 includes a voltage conversion circuit 21, a voltage correction circuit 22 connected in parallel with the voltage conversion circuit 21, an input terminal 23, and an output terminal 24. The voltage conversion circuit 21 has a switching circuit 25 and a PWM control circuit 26. The PWM control circuit 26 controls the on / off operation of the switching element according to the conversion voltage VoA2 of the switching circuit 25, thereby stabilizing the conversion voltage VoA2. Furthermore, the voltage correction circuit 22 has the function of boosting the conversion voltage VoA2 only when the input voltage Vin2 input to the voltage conversion circuit 21 is lower than a predetermined voltage.

[0029] like Figure 1As shown, power supply unit 1 outputs a drive voltage Vout to drive load device 30. This drive voltage Vout is generated by connecting the output voltages VoK1 and VoK2 from the output terminals 14 and 24 of the two power supply units 10 and 20 in parallel. The input terminals 13 and 23 of the two power supply units 10 and 20 are electrically insulated from each other. The two power supply units 10 and 20 operate redundantly, sharing the power supplied to load device 30.

[0030] Furthermore, when the input voltage Vin1 of either power supply unit 10 decreases, the power supply to the load device 30 becomes insufficient, and the drive voltage Vout temporarily decreases. The system detects this voltage decrease and increases the power supplied by the other power supply unit 20, restoring the temporarily decreased drive voltage to the specified voltage.

[0031] The following explains how to implement this functionality. First, for the... Figure 1 The operation of the power supply device 1 of the first embodiment shown is described assuming that the voltage correction circuits 12 and 22 of the two power supply units 10 and 20 are not connected.

[0032] When the input of a power supply unit 10 is cut off, the input voltage Vin1 to the voltage conversion circuit 11 decreases. As the input voltage Vin1 decreases, the voltage at which the switching element of the switching circuit 15 is turned on / off also decreases, resulting in a decrease in the conversion voltage VoA1. At this time, the PWM control circuit 16 of the voltage conversion circuit 11 detects the decrease in the conversion voltage VoA1 and sends a signal to increase the on / off ratio of the switching element. The switching circuit 15 receives this signal and extends the on-time of the switching element, causing the conversion voltage VoA1 to rise and maintain the specified conversion voltage VoA1.

[0033] However, when the input of power supply unit 10 is cut off, the input voltage Vin1 decreases monotonically and continuously. Therefore, the operation of the switching circuit 15 to extend the conduction time of the switching element by simply detecting the decrease in the conversion voltage VoA1 cannot maintain the specified conversion voltage VoA1, and the conversion voltage VoA1 will eventually decrease. As a result, the output voltage VoK1 from the output terminal 14 of power supply unit 10 also decreases.

[0034] The two power supply units 10 and 20 of the power supply device 1 are connected in parallel and operate redundantly, sharing the power required by the load device 30. Therefore, when the output voltage VoK1 from the output terminal 14 of the power supply unit 10 decreases, the power supply to the load device 30 is insufficient, and the drive voltage Vout also decreases. When the drive voltage Vout decreases, the output voltage VoK2 from the output terminal 24 of the other power supply unit 20 also decreases accordingly. When the output voltage VoK2 from the output terminal 24 decreases, the switching voltage VoA2 of the switching circuit 25 of the power supply unit 20 also decreases further.

[0035] The PWM control circuit 26 of the voltage conversion circuit 21 detects the decrease in the conversion voltage VoA2 and sends a signal to increase the on / off ratio of the switching element. The switching circuit 25 receives this signal and extends the on-time of the switching element, causing the conversion voltage VoA2 to rise and restoring the temporarily reduced output voltage VoK2 of the power supply unit 20 to the specified voltage. Therefore, even if the input to the power supply unit 10 is completely cut off and the output from the power supply unit 10 is completely stopped, the power supply unit 20 can still provide the power required by the load device 30 independently.

[0036] However, the PWM control circuit 26 of the power supply unit 20 detects a decrease in the voltage at the contact of the output voltage VoK2 of the power supply unit 20 and sends a control signal to the switching circuit 25 to extend the on-time of the switching element. The switching circuit 25 receives this signal and extends the on-time of the switching element, causing the conversion voltage VoA2 to rise. It takes a certain amount of time for the output voltage VoK2 from the output terminal 24 to recover. Therefore, when the output voltage VoK1 drops sharply as when the input to the power supply unit 10 is cut off, a temporary instantaneous voltage drop in the drive voltage Vout inevitably occurs during the period before the power supply unit 20 strengthens its power supply.

[0037] Next, the operation of the power supply unit 10 with the voltage correction circuit 12 will be explained. When the input voltage Vin1 is detected to be lower than the predetermined voltage, the voltage correction circuit 12 pulls down the voltage at the terminal of the PWM control circuit 16 that monitors the conversion voltage VoA1. When the voltage at the contact of this input terminal is pulled down, the PWM control circuit 16 performs the same operation as when the decrease in the conversion voltage VoA1 is detected, that is, it outputs a signal to the switching circuit 15 to extend the on-time of the switching element and boosts the conversion voltage VoA1. Using this function, during the period when the input voltage Vin1 is lower than the predetermined voltage, the voltage conversion circuit 11 continuously outputs a conversion voltage VoA1 boosted by a predetermined ratio compared to the original conversion voltage VoA1 that should be output corresponding to the input voltage Vin1.

[0038] As described above, the voltage correction circuit 12 can boost the conversion voltage VoA1 during the transient response until it stops decreasing, thereby reducing the rate of decrease. Therefore, the voltage correction circuit 12 of the power supply unit 10 can suppress the magnitude of the instantaneous voltage drop that occurs during the period before the drive voltage Vout, which is temporarily reduced by the power supply unit 20, is restored, and boost the output voltage VoK1 by a predetermined proportion.

[0039] In a load device 30 powered by a drive voltage Vout, an operable power supply voltage range is typically set. When the drive voltage Vout falls below this operable power supply voltage range due to a momentary voltage drop, the load device 30 may sometimes stop. Therefore, the magnitude of the momentary voltage drop must be set within a range that prevents the load device from stopping, and the function of suppressing the magnitude of the momentary voltage drop is important.

[0040] The above describes the situation where the input of power supply unit 10 is cut off. However, even when the input of power supply unit 20 is cut off, the same operation can be performed by the voltage correction circuit 22 of power supply unit 20 and power supply unit 10.

[0041] Figure 2 It shows Figure 1 A detailed circuit diagram of the first embodiment of the power supply device is provided. The switching circuit 15 includes a switching element that switches the on / off ratio of the input voltage Vin1 and generates a pulse signal, a drive circuit SW that drives the switching element, and a low-pass filter composed of an inductor and a capacitor. The switching element can be, for example, constructed from an insulated-gate field-effect transistor.

[0042] The PWM control circuit 16 consists of a comparator Com1 that compares the voltage generated by the output voltage VoK1 of the switch circuit 15 through a resistor divider circuit with the reference voltage Vref1, and a control unit PWM that controls the drive circuit SW of the switch circuit 15 based on the output of the comparator Com1.

[0043] The voltage correction circuit 12 monitors the input voltage Vin1 using comparator Com2, which compares the voltage generated from the input voltage Vin1 by the resistor divider circuit with the reference voltage Vref2. Additionally, comparator Com3, which compares the output of comparator Com2 with the reference voltage Vref3, switches its output element from a non-conducting state to a conducting state in response to the input voltage Vin1 becoming lower than a predetermined voltage.

[0044] Because the output element is in the ON state, the input voltage Vph of comparator Com1 in the PWM control circuit 16 is further reduced than the voltage generated by resistive voltage division of the input voltage Vin1. Therefore, the input voltage to the PWM control circuit 16 is lower than the voltage obtained by resistive voltage division of the actual voltage VoA1 of the switching circuit 15. As a result, the original correction of the PWM control circuit 16 is overcorrected, causing the switching voltage VoA1 of the switching circuit 15 to be further boosted than the voltage it should have output.

[0045] The output element of the voltage correction circuit 12 can be constructed using an optocoupler. Alternatively, a transistor can be used instead of an optocoupler.

[0046] The input and output of the switching circuit 15 are controlled by a switching element to be on / off, i.e., on / off, but they may not be completely electrically isolated.

[0047] Figure 3A and Figure 3B It shows the Figure 1 Timing diagram of the input of a power supply unit of power supply device 1 when it is cut off. Figure 3A It is a general power supply device that connects two power supply units for PWM control in parallel for redundant operation, that is, in order to... Figure 1 The timing diagram for a power supply unit when the input of a power supply unit is cut off is shown when the voltage correction circuits 12 and 22 are not connected in the power supply device 1. Figure 3B This is a timing diagram in the first embodiment of the power supply device 1 when the input of a power supply unit is cut off.

[0048] First of all, Figure 3A The timing diagram described herein will be used for explanation. During stable operation, input voltage Vin1 is input to one power supply unit 10, and input voltage Vin2 is input to another power supply unit 20. The respective output voltages VoK1 and VoK2 are connected in parallel to generate the drive voltage Vout supplied to the load device 30. Here, the output voltages VoK1, VoK2, and drive voltage Vout are approximately the same voltage value, and the power supplied to the load device 30 is shared by one power supply unit 10 and the other power supply unit 20.

[0049] Here, when the input to power supply unit 10 is cut off, the input voltage Vin1 decreases. If the decrease in input voltage Vin1 is within a certain range, the output voltage VoK1 is maintained by PWM control. However, when the input voltage Vin1 decreases significantly beyond a predetermined voltage (a1), the output voltage VoK1 also begins to decrease (a3). The parallel-connected output voltage VoK2 also begins to decrease in conjunction with this (a2).

[0050] When the PWM control circuit 26 of the power supply unit 20 detects a decrease in the output voltage VoK2, the switching circuit 25 extends the on-time of the switching element to boost the output voltage VoK2. As the output voltage VoK1 continues to decrease, the power supply unit 10 enters a stop state, but by increasing the power supplied by the power supply unit 20, the drive voltage Vout recovers to the specified voltage. Then, the power supply device 1 returns to stable operation by being powered solely by the power supply unit 20.

[0051] However, it takes a certain amount of time from when the power supply unit 20 detects a decrease in the output voltage VoK2 until the drive voltage Vout recovers to the specified voltage. Therefore, a momentary voltage drop in the drive voltage Vout during this period is unavoidable.

[0052] Next, regarding Figure 3B The timing diagram described in the document will be used for illustration. During stable operation, it will be... Figure 3A Similarly, in the timing diagram described, input voltage Vin1 is input to one power supply unit 10, and input voltage Vin2 is input to another power supply unit 20, which outputs output voltages VoK1 and VoK2 respectively. These outputs are connected in parallel to generate the drive voltage Vout supplied to the load device 30. Here, output voltages VoK1, VoK2, and Vout are approximately the same voltage value, and the power supplied to the load device 30 is shared by one power supply unit 10 and the other power supply unit 20.

[0053] Here, when the input to power supply unit 10 is cut off, the input voltage Vin1 decreases. If the decrease in input voltage Vin1 is within a certain range, the output voltage VoK1 is maintained by PWM control. However, as... Figure 3A As shown, it is known that with only general PWM control, when the input voltage Vin1 greatly exceeds the predetermined voltage (a1) and decreases, the output voltage VoK1 (a3) ​​also begins to decrease.

[0054] Therefore, in response to the input voltage Vin1 dropping to a predetermined voltage A1 at time t1, the voltage correction circuit 12 causes the output voltage Vcp of comparator Com3 to go low, and at time t2, it will output the element ( Figure 2 The PWM control circuit 16, which switches from a non-conducting state to a conducting state, has an input terminal that monitors the switching voltage VoA1 of the switching circuit 15. When the output element of the voltage correction circuit 12 becomes conducting, the input voltage Vph of this input terminal is pulled down to a low level.

[0055] When the input voltage Vph at the input terminal decreases, the PWM control circuit 16 performs the same operation as when the conversion voltage VoA1 decreases, that is, it sends a signal to extend the on-time of the switching element of the switching circuit 15 and boosts the conversion voltage VoA1. Although the boosting operation requires a certain amount of time, the boosting operation actually starts from time t2 before the output voltage VoK1 at the output terminal 14 begins to decrease at time t3. Therefore, the boosting operation of the PWM control circuit 16 takes effect on the output voltage VoK1 immediately after the output voltage VoK1 at the output terminal 14 begins to decrease at time t3.

[0056] On the other hand, at time t3, when the output voltage VoK1 begins to decrease, the output voltage VoK2 also decreases accordingly. When the PWM control circuit 26 of the power supply unit 20 detects this voltage decrease, the switching circuit 25 controls the on-time of the switching elements to be extended. The output voltage VoK1 continues to decrease, and the power supply unit 10 enters a stop state, but by increasing the power provided by the power supply unit 20, the drive voltage Vout recovers to the specified voltage. Then, the power supply device 1 returns to stable operation by being powered solely by the power supply unit 20.

[0057] Since the boost operation of the PWM control circuit 16 takes effect immediately after time t3, the rate of decrease of the output voltage VoK1 after time t3 is reduced. Therefore, because the slope of the decrease in output voltage VoK1 from time t3 becomes slower, the slope of the decrease in drive voltage Vout also becomes slower. Consequently, due to the delayed decrease in drive voltage Vout, the increase in power supply from power unit 20 is effective when the voltage decrease is small. Therefore, the decrease in instantaneous voltage generated during the period when drive voltage Vout recovers to the specified voltage is suppressed only for dVout.

[0058] Figure 4A and Figure 4B The text shows that in Figure 1 Timing diagram of restarting a power supply unit whose input has been cut off in power supply device 1.

[0059] Figure 4A It is a general power supply device that connects two power supply units for PWM control in parallel for redundant operation, that is, in Figure 1 The timing diagram for restarting a power supply unit whose input is cut off in the power supply device 1 without the voltage correction circuits 12 and 22 is shown. During the period when power supply unit 10 is stopped, power supply device 1 operates stably by being powered solely by power supply unit 20.

[0060] Here, when the input voltage Vin1 is supplied to the power supply unit 10, the output voltage VoK1 rises according to the rise of the input voltage Vin, and converges to a constant voltage output operation when the output voltage VoK1 reaches a specified voltage. Figure 4A In this case, control is performed solely through PWM control, and the slope of the output voltage VoK1 rise is set to be the same in both regions b1 and b2.

[0061] Figure 4B This is a timing diagram of restarting a power supply unit 10 when its input is cut off, according to the first embodiment of the power supply device 1. The power supply device 1 operates stably during the period when the power supply unit 10 is stopped, powered solely by the power supply unit 20.

[0062] Here, when the input voltage Vin1 is supplied to the power supply unit 10, during the period when the input voltage Vin1 is lower than B3, the output voltage Vcp of the comparator Com3 of the voltage correction circuit 12 is low, and the output element ( Figure 2 The bipolar transistor remains in the ON state. Therefore, the input voltage at the input terminal that monitors the conversion voltage VoA1 of the switching circuit 15 of the PWM control circuit 16 becomes lower than the voltage corresponding to the actual conversion voltage VoA1. Consequently, in region B1, the voltage becomes higher than the conversion voltage VoA1 that should have been output corresponding to the input voltage Vin1, and the output voltage VoK1 output from the output terminal 14 via the diode element 17 also becomes higher.

[0063] However, when the input voltage Vin1 rises and reaches the predetermined voltage B3 at time t1, the output voltage Vcp of the comparator Com3 of the voltage correction circuit 12 becomes high, and at time t2, the output element ( Figure 2 The bipolar transistor switches from the on state to the off state. As a result, the input voltage of the input terminal that monitors the conversion voltage VoA1 of the switching circuit 15 of the PWM control circuit 16 becomes the voltage corresponding to the actual conversion voltage VoA1. In the B1 region after time t3, the voltage correction circuit 12 does not function, and only the PWM control circuit 16 restores the stable operation of maintaining the conversion voltage VoA1.

[0064] Therefore, even when a power supply unit 10 whose input has been cut off is restarted, the voltage correction circuit 12 operates, but the restart characteristics are not affected.

[0065] Figure 5 A modified example of a detailed circuit diagram of the first embodiment of the power supply device 1 shown in FIG4 is illustrated. In this modified example of the first embodiment, the input side and the output side of the switching circuit 15 are coupled through an insulating transformer, and the input and output of the switching circuit 15 are always electrically isolated.

[0066] Figure 1 The power supply device 1 shown may also include an input circuit 18 between the input terminal 13 of a power supply unit 10 and the voltage conversion circuit 11. This input circuit 18 converts the voltage Vext1 input to the input terminal 13 into an input voltage Vin1 input to the voltage conversion circuit 11. This input circuit 18 may include an AC / DC converter or a DC / DC converter.

[0067] Similarly, for the other power supply unit 20, an input circuit 28 can also be included between the input terminal 23 and the voltage conversion circuit 21. This input circuit 28 converts the voltage Vext2 input to the input terminal 23 into an input voltage Vin2 input to the voltage conversion circuit 21. This input circuit 28 may include an AC / DC converter or a DC / DC converter.

[0068] The input terminal 13 of one power supply unit 10 is electrically insulated from the input terminal 23 of another power supply unit 20. Vext1, which is input to one power supply unit 10, and Vex2, which is input to the other power supply unit 20, are provided independently of each other.

[0069] <Second Implementation Method>

[0070] Figure 6 The diagram shows a circuit block diagram of a second embodiment of the power supply device 101. In a power supply unit 110, a diode element 117 is connected in series between the switching circuit 115 of the voltage conversion circuit 111 and the output terminal 114. The diode element 117 prevents current from flowing from the output terminal 114 to the voltage conversion circuit 111 when the conversion voltage VoA1 output from the voltage conversion circuit 111 decreases.

[0071] A potential difference may sometimes occur between the two terminals (anode and cathode) of such a diode element 117. In the second embodiment, a cathode control circuit 119 is also included, which provides a signal to the PWM control circuit 116 to correct this potential difference. The cathode control circuit 119 provides a signal corresponding to the conversion voltage VoA1 of the voltage conversion circuit 111 and the output voltage VoK1 of the output terminal. Furthermore, in this second embodiment, when the input voltage Vin1 input to the voltage conversion circuit 111 is lower than a predetermined voltage, the voltage correction circuit 112 boosts the conversion voltage VoA1 via the cathode control circuit 119.

[0072] Similarly, in another power supply unit 120, a diode element 127 is connected in series between the switching circuit 125 of the voltage conversion circuit 121 and the output terminal 124. The diode element 127 prevents current from flowing from the output terminal 124 to the voltage conversion circuit 121 when the conversion voltage VoA2 output from the voltage conversion circuit 121 decreases.

[0073] A potential difference may sometimes occur between the terminals (anode and cathode) of such a diode element 127. A cathode control circuit 129 may also be included, which provides a signal to the PWM control circuit 126 to correct this potential difference. The cathode control circuit 129 provides a voltage corresponding to the conversion voltage VoA2 of the voltage conversion circuit 121 and the output voltage VoK2 at the output terminal. Additionally, in this variation, when the input voltage Vin2 input to the voltage conversion circuit 121 is lower than a predetermined voltage, the voltage correction circuit 122 controls the operation of the PWM control circuit 126 via the cathode control circuit 129 to boost the conversion voltage VoA2.

[0074] Figure 7 It shows Figure 6 A detailed circuit diagram of the second embodiment of the power supply device is provided. The cathode control circuit 119 is composed of a comparator Com4, which compares the voltage generated by resistive voltage division of the conversion voltage VoA1 with the voltage generated by resistive voltage division of the output voltage VoK1. The output of comparator Com4 is input to the terminal on the reference voltage Vref1 side of comparator Com1 in the PWM control circuit 116, enabling PWM control that corrects the potential difference between the conversion voltage VoA1 and the output voltage VoK1.

[0075] Additionally, the output of the voltage correction circuit 112 is connected to the resistor divider circuit on the VoA1 side of the cathode control circuit. When the input voltage Vin1 is lower than a predetermined voltage, the PWM control circuit controls the switching circuit 115 to further boost the conversion voltage VoA1. The remaining structure is the same as... Figure 5 The first embodiment shown is the same.

[0076] Figure 8 It shows Figure 7 A modified example of the detailed circuit diagram of the second embodiment of the power supply device. In this modified example of the second embodiment, the input side and the output side of the switching circuit 15 are coupled through an insulation transformer, and the input and output of the switching circuit 15 are always electrically isolated.

[0077] The above refers to those with two Figure 1 or Figure 6The power supply device with the structure of the power supply unit shown has been described, but this disclosure is not limited thereto and also includes power supply devices having three or more power supply units. In this case, the load device is driven by a drive voltage formed by connecting the output voltages output from the respective output terminals of the multiple power supply units in parallel. The respective input terminals of the multiple power supply units are electrically insulated from each other. These multiple power supply units connected in parallel are configured for redundant operation and the power required by the load device is shared by the multiple power supply units.

[0078] Furthermore, it can be configured to detect a decrease in drive voltage when the input voltage of one of the multiple power supply units decreases, thereby increasing the output power of the other power supply units and restoring the decreased drive voltage to a specified voltage.

[0079] According to another aspect of the power supply device of this application, each of the two power supply units further includes an input circuit that provides an input voltage to an input terminal, the input circuit being supplied with voltage from a plurality of external power supplies that are electrically isolated from each other, the input circuit converting the supplied voltage into an input voltage, the input circuit including an AC / DC converter or a DC / DC converter.

[0080] Label Explanation

[0081] 1. 101 Power Supply Unit

[0082] 10, 20, 110, 120 power supply units

[0083] Voltage conversion circuits 11, 21, 111, 121

[0084] Voltage correction circuits 12, 22, 112, 122

[0085] Input terminals 13, 23, 113, 123

[0086] Output terminals 14, 24, 114, 124

[0087] 15, 25, 115, 125 switching circuits

[0088] 16, 26, 116, 126 PWM control circuits

[0089] 17, 27, 117, 127 diode components

[0090] 18, 28, 118, 128 input circuits

[0091] 30, 130 load devices.

Claims

1. A power supply device, characterized in that, It includes two power supply units, each power supply unit comprising: A voltage conversion circuit includes a switching circuit and a PWM control circuit. The switching circuit outputs an output voltage corresponding to the input voltage, and the PWM control circuit controls the switching circuit to turn on / off based on the output voltage, thereby stabilizing the output voltage. A voltage correction circuit that boosts the output voltage only when the input voltage is lower than a predetermined voltage; Input terminals; as well as Output terminals, The input terminals of the two power supply units are electrically insulated from each other. The two power supply units drive the load device using a single drive voltage formed by connecting the output voltages from their respective output terminals in parallel. When the input voltage of one of the two power supply units decreases, the driving voltage is detected to decrease along with the decrease in the input voltage. The other power supply unit then restores the decreased driving voltage to a predetermined voltage. When the input voltage of one of the power supply units is cut off, the voltage correction circuit detects that the input voltage has become lower than the predetermined voltage and boosts the output voltage, thereby reducing the rate of decrease of the output voltage caused by the cutoff of the input voltage and suppressing the instantaneous voltage drop of the drive voltage supplied to the load device.

2. The power supply device as described in claim 1, characterized in that, The instantaneous voltage drop is controlled within the range where the load device does not stop.

3. The power supply device as described in claim 1, characterized in that, Each voltage correction circuit has a comparator and an output element. The comparator monitors the input voltage and, upon detecting that the input voltage has become lower than the predetermined voltage, switches the output element from a non-conducting state to a conducting state.

4. The power supply device as described in claim 3, characterized in that, The output element includes an optocoupler or a transistor.

5. The power supply device according to any one of claims 1 to 4, characterized in that, The input and output of the switching circuit are not electrically isolated.

6. The power supply device according to any one of claims 1 to 4, characterized in that, The switching circuit has an insulating transformer, and the input and output of the switching circuit are electrically insulated from each other.

7. The power supply device according to any one of claims 1 to 4, characterized in that, A diode element is connected in series between the switching circuit and the output terminal of the voltage conversion circuit. The power supply device also includes a cathode control circuit, which provides a signal to the PWM control circuit to correct the potential difference between the two terminals of the diode element.

8. The power supply device as described in claim 1, characterized in that, When the input voltage is restored to the power supply unit whose input voltage has been cut off, and the input voltage is detected to have risen above the predetermined voltage, the voltage correction circuit stops controlling the boosting of the output voltage.

9. The power supply device according to any one of claims 1 to 4, characterized in that, Each of the two power supply units further includes an input circuit that provides the input voltage to the input terminal, and provides voltage from a plurality of external power supplies that are electrically isolated from each other to the input circuit, the input circuit converting the provided voltage into the input voltage.

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