JP7181075B2 - power supply - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply, and more particularly to a power supply to which AC voltage is input.

2. Description of the Related Art At present, a three-wire input power supply, such as an AC/DC converter, which inputs either a single-phase alternating current or a three-phase alternating current and outputs a direct current voltage, is widely used. Some power supply devices of this type have a function, such as a power failure detection circuit, that detects the value of the input AC voltage and automatically starts or stops the power supply device.

In the above power failure detection circuit, generally, the input AC voltage is full-wave rectified, the rectified voltage is smoothed, and then the voltage is further divided to set the detection voltage. Then, this set voltage and a predetermined threshold (reference voltage) are compared by a comparison circuit such as a comparator, and when the predetermined threshold is reached, a procedure for starting or stopping the power supply device is started. In addition, in the stop determination, a hysteresis circuit provided in a comparator is used to stop the power supply device at a threshold voltage lower than that at startup.

In addition, this type of power supply device is further equipped with an internal auxiliary power supply for driving the power failure detection circuit itself, and starting and stopping the internal auxiliary power supply has a voltage lower than that of the main body of the power supply. must be done in

For example, at start-up, the internal auxiliary power supply is first started with a predetermined input voltage, the predetermined auxiliary power supply voltage is supplied, and thereafter, when the input voltage further rises, the power supply main body starts the startup procedure. On the other hand, when stopping, it is necessary to first stop the power supply main body to stop outputting the DC voltage at a predetermined input voltage, and then stop the internal auxiliary power supply when the input voltage further drops.

As described above, in the power failure detection circuit described above, after smoothing the full-wave rectified voltage of the input AC voltage, the voltage is further divided to set the detection voltage. Then, this set voltage is compared with a predetermined threshold voltage. However, when the value of the input AC voltage is the same, the voltage obtained by smoothing this full-wave rectified voltage is considerably higher for three-phase AC than for single-phase AC. Therefore, the three-phase alternating current reaches the threshold voltage for judging start and stop at a lower input voltage value than the single-phase alternating current, which is a problem.

In this way, if the determination voltage for starting and stopping voltages when a three-phase AC is input is too low, the order of starting and stopping the internal auxiliary power supply will be reversed, which will be a factor in inducing malfunction of the power supply. .

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and its object is to start and operate a motor for the same input voltage value regardless of whether single-phase AC or three-phase AC is input. The configuration is such that the decision to stop is made, the order of starting and stopping the internal auxiliary power supply and the starting and stopping of the main power supply unit is followed, and the full-wave rectified voltage is different for single-phase AC and three-phase AC. The present invention realizes a power supply device that avoids the malfunction caused by the problem.

A power supply device according to a first aspect of the present invention includes three input terminals to which AC voltage is input, a full-wave rectifier circuit connected to each of the three input terminals and outputting a full-wave rectified voltage of the AC voltage, a level adjustment circuit that outputs a detection level signal based on the full-wave rectified voltage; a first determination circuit that receives the detection level signal and outputs a control signal based on the detection level signal; and a second determination circuit that outputs a drive signal, and a level adjustment circuit adjusts the value of the detection level signal according to the drive signal.

According to a second aspect of the present invention, in the first aspect, the level adjustment circuit includes a level adjustment section having one end connected to ground potential, and the level adjustment section includes a full-wave rectifier circuit and the ground potential. , and outputs the divided voltage as a detection level signal.

According to a third aspect of the present invention, in the above-described second aspect, the level adjustment circuit has a variable resistance element whose resistance value changes in accordance with the drive signal supplied from the second determination circuit; The value of the detection level signal is adjusted by changing the resistance value of the variable resistance element according to the signal.

According to a fourth aspect of the present invention, in the third aspect, the second determination circuit uses a full-wave rectified voltage to determine that the AC voltage input to the three input terminals is single-phase AC. or three-phase AC.

According to a fifth aspect of the present invention, in any one of the second to fourth aspects, the level adjustment section includes a first resistor connected in series between the full-wave rectifier circuit and the ground potential. and an adjusting element connected in parallel with the first resistive element, the adjusting element comprising a second resistive element and a switching element connected in series.

According to a sixth aspect of the present invention, in the fifth aspect, the switching element of the level adjusting section is turned on or off by the drive signal supplied from the second determination circuit.

According to a seventh aspect of the present invention, in the above fifth or sixth aspect, the drive signal controls the switching element of the level adjustment section when the AC voltage input to the three input terminals is a three-phase AC voltage. When single-phase alternating current is input to any two of the three input terminals, the switching element of the level adjusting section is turned off.

According to an eighth aspect of the present invention, in the seventh aspect, when the AC voltage input to the three input terminals is a three-phase AC, and one of the phases is open, the level The switching element of the control section is turned off.

According to a ninth aspect of the present invention, in any one of the sixth to eighth aspects, when the switching element of the level adjusting section is in the ON state, the detection level signal is higher than when the switching element is in the OFF state. value becomes lower.

According to a tenth aspect of the present invention, in any one of the second to ninth aspects, the level adjustment circuit may be a three-phase AC voltage or a single-phase AC voltage. output the detection level signal of the same value for the same AC voltage.

According to an eleventh aspect of the present invention, in any one of the second to tenth aspects, the control signal output by the first determination circuit is either a start signal or a stop signal, and the detection level A start signal is output when the signal exceeds the first reference voltage, and the stop signal is output when the detection level signal is below the first reference voltage.

According to a twelfth aspect of the present invention, in any one of the second to eleventh aspects, the level adjustment circuit includes a voltage divider connected in series between the full-wave rectifier circuit and the level adjustment section. It further includes a part.

According to a thirteenth aspect of the present invention, in the eleventh aspect, the first determination circuit includes a first comparator that compares the detection level signal and the first reference voltage; and an output circuit that converts the output of the device to a control signal.

According to a fourteenth aspect of the present invention, in any one of the first to thirteenth aspects, the second determination circuit includes a voltage dividing circuit that divides the full-wave rectified voltage; a second comparator for comparing the rectified voltage and the second reference voltage; a time constant circuit for receiving the output of the second comparator; and a third comparator for comparing the output of the time constant circuit and the third reference voltage. and a drive circuit that receives the output of the third comparator and outputs a drive signal.

According to a fifteenth aspect of the present invention, in any one of the first to fourteenth aspects, each of the first determination circuit and the second determination circuit is driven by a common operating power supply voltage.

According to the power supply device of the present invention, regardless of whether a single-phase alternating current or a three-phase alternating current is input, the determination of start and stop is made for the same input voltage value, and the internal auxiliary power supply starts and stops. A power supply that avoids malfunctions caused by different single-phase and three-phase full-wave rectified voltages by observing the order of stopping and starting and stopping the main body of the power supply.

It is drawing which shows the circuit block diagram of embodiment of this invention. FIG. 4 is a diagram showing waveforms of contacts at the time of start detection when the single-phase AC input voltage rises according to the embodiment of the present invention. FIG. 4 is a diagram showing waveforms of respective contacts at the time of start detection when the three-phase AC input voltage rises according to the embodiment of the present invention; FIG. 4 is a diagram showing waveforms of contacts at the time of stop detection when the single-phase AC input voltage drops according to the embodiment of the present invention. FIG. 4 is a diagram showing waveforms of contacts at the time of stop detection when the three-phase alternating current input voltage drops according to the embodiment of the present invention; FIG. 4 is a diagram showing changes in waveform of each contact when one phase is open in a three-phase alternating current input according to the embodiment of the present invention. FIG. 4 is a diagram showing changes in waveform of each contact when a missing phase is restored in a three-phase alternating current input according to the embodiment of the present invention. FIG. 10 is a diagram showing a comparator with hysteresis characteristics applicable to circuits of embodiments of the present invention; FIG. 10 is a diagram showing a comparator with hysteresis characteristics applicable to circuits of embodiments of the present invention;

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below based on the drawings.

FIG. 1 is a drawing showing a circuit block diagram of an embodiment of a power supply device of the present invention. This circuit block has three input terminals U, V, and W to which AC voltages are input, and has an input rectifier 3 capable of outputting a DC voltage. A three-phase AC voltage can be input to the three input terminals U, V, W, or a single-phase AC voltage can be input to any two terminals. A full-wave rectifier circuit 5 for outputting a full-wave rectified AC voltage is connected.

A level adjustment circuit 10 is connected to the full-wave rectifier circuit 5, and this level adjustment circuit 10 outputs a detection level signal based on the received full-wave rectified voltage. The level adjustment circuit 10 is connected to the first determination circuit 20 via the detection level signal supply line 14, and the first determination circuit receives the detection level signal. The first determination circuit 20 has a signal output terminal 22 and outputs to the signal output terminal 22 a start or stop signal for the power supply device, which is a control signal determined based on the received detection level signal.

On the other hand, a second determination circuit 30 is further connected to the full-wave rectifier circuit 5 . This second determination circuit 30 outputs a drive signal (Q1_Vgs) based on the full-wave rectified voltage received from the full-wave rectifier circuit 5 . This drive signal (Q1_Vgs) is input to the level adjustment circuit 10, and the level adjustment circuit 10 outputs the voltage value of the detection level signal based on the full-wave rectified voltage in response to the reception of this drive signal (Q1_Vgs). can be adjusted.

The level adjusting circuit 10 can include a level adjusting section 11 having one end connected to the ground potential. The level adjustment unit 11 is connected in series between the full-wave rectifier circuit 5 and the ground potential, smoothes the full-wave rectified voltage with, for example, a capacitor element, and further divides the smoothed voltage. , can be output as a detection level signal.

Also, the level adjusting section 11 can have a variable resistance element whose electric resistance value changes in response to the drive signal (Q1_Vgs) received from the second determination circuit 30 . When the electrical resistance value of the variable resistance element changes, the value of the divided voltage in the level adjustment section 11 changes, so that the voltage value of the detection level signal output from the level adjustment circuit 10 can be changed.

Based on the full-wave rectified voltage output from the full-wave rectifier circuit 5, the second determination circuit 30 determines whether the AC voltage input to the three input terminals U, V, and W is single-phase AC, It can be determined whether it is a three-phase alternating current. Also, the second determination circuit 30 can be driven by a common operating power supply voltage together with the first determination circuit 20 .

The full-wave rectifier circuit 5 has a configuration in which diodes D1, D2, and D3 are connected to three input terminals U, V, and W, respectively. Therefore, when a single-phase AC voltage is input to any two of the three input terminals U, V, and W, the full-wave rectified voltage output by the full-wave rectifier circuit 5 is the divided voltage of FIG. As shown in the waveform of the voltage (V_R9), there is a point where the voltage becomes 0 V every half cycle of the single-phase AC voltage. On the other hand, when a three-phase AC voltage is input to the three input terminals U, V, and W, the full-wave rectified voltage is a voltage above a certain level, as shown in the waveform of the divided voltage (V_R9) in FIG. It becomes a waveform that oscillates with a small amplitude while maintaining the value.

Using the difference in the waveforms of these divided voltages (V_R9), for example, as shown in the divided voltage (V_R9) waveforms in FIGS. 2 and 3, a predetermined voltage Vref2 is set to By comparing with the waveform of V_R9), it is possible to determine whether the voltage input to the three input terminals U, V, and W is single-phase AC or three-phase AC.

The variable resistance elements of the level adjusting section 11 described above include a first resistance element R3 connected in series between the full-wave rectifier circuit 5 and the ground potential, and a first resistance element R3 connected in parallel with the first resistance element R3. an adjustment element, which may be composed of a second resistive element R4 and a switching element Q1 connected in series.

The switching element Q1 can be, for example, an insulated gate field effect transistor. A driving signal (Q1_Vgs) output from the second determination circuit 30 is connected to the gate electrode of the switching element Q1, and the switching element Q1 can be switched between an ON state and an OFF state according to the voltage value of this driving signal. can.

The level adjusting circuit 10 further includes a voltage dividing section 12 connected in series between the full-wave rectifying circuit 5 and the level adjusting section 11 . The voltage value of the detection level signal can be determined by the resistance ratio between the voltage dividing section 12 and the level adjusting section 11 .

When the switching element Q1 is in the OFF state, the second resistance element R4 is in the open state, so that the electrical resistance value of the level adjusting section 11 is the same as the resistance value of the first resistance element R3. On the other hand, when the switching element Q1 is in the ON state, the second resistance element R4 is connected in parallel with the first resistance element R3. A combined resistance value is obtained when the element R3 and the second resistance element R4 are connected in parallel, which is lower than the resistance value of the first resistance element R3 alone.

Therefore, when the switching element Q1 is in the ON state, the electric resistance value of the level adjusting section 11 is lower than when the switching element Q1 is in the OFF state. The voltage of the signal is also lower when the switching element Q1 is on than when it is off.

Next, the first determination circuit 20 will be described.

The first decision circuit 20 includes a first comparator 26 and an output circuit 28 . The first comparator 26 compares the voltage of the detection level signal received from the detection level signal supply line with the predetermined first reference voltage 25 . When the voltage of the detection level signal exceeds the first reference voltage 25, it outputs a low level voltage (see the waveform of CMP1_V0 in FIGS. 2 and 3). (see the waveform of CMP1_V0 in FIG. 5).

The voltage of this detection level signal has a characteristic that it increases as the input AC voltage rises and decreases as the input AC voltage falls. Therefore, by adjusting the voltage division characteristic of the level adjustment circuit 10 and the first reference voltage 25, when the input AC voltage reaches a predetermined voltage at the start of AC voltage application, the first determination circuit 20 starts up. signal can be output. Further, when the input AC voltage tends to decrease, the stop signal can be output from the first determination circuit 20 when the input AC voltage falls below a predetermined voltage.

However, if the value of the input AC voltage for outputting the start signal and the value of the input AC voltage for outputting the stop signal are the same, when the input AC voltage oscillates near the output determination voltage of the start/stop signal, a short Since the start/stop signal will be continuously output within the time, the operation of the first comparator 26 may become unstable. In order to avoid this, as shown in FIG. 8, resistance elements R5 and R6 and a diode element D4 are added to the first comparator 26 to provide hysteresis characteristics when the input voltage rises and falls. can let

When a comparator having this hysteresis characteristic is applied as the first comparator 26 to the circuit shown in FIG. The circuit constants can be set so that the stop signal is output after the voltage drops to 70 V when the voltage drops.

Based on the output of the first comparator 26, the output circuit 28 outputs a start signal for the power supply when the output is at a low level, and outputs a stop signal for the power supply when the output is at a high level. can be output. Although not particularly illustrated, a circuit block that receives these start signals or stop signals and performs an operation to start or stop the power supply device including the input rectifier 3 can be further provided.

As described above, in this embodiment, when the power is turned on, it is possible to detect a rise in the input AC voltage and output the activation signal of the power supply device. Also, when the power supply is turned off, it is possible to detect a drop in the input AC voltage and output a power supply stop signal.

Furthermore, by constantly monitoring the value of the input AC voltage, the power supply is stopped when the voltage drops below a predetermined voltage during a power outage, and when the voltage rises above the predetermined voltage when the power is restored. Accordingly, it becomes possible to start the power supply device.

Next, the second determination circuit 30 will be explained.

A second determination circuit 30 includes a voltage dividing circuit 31 that divides the full-wave rectified voltage output from the full-wave rectifying circuit 5 to output a predetermined divided voltage (V_R9), and an output of the voltage dividing circuit 31 A second comparator 33 compares the voltage value of V_C with a second reference voltage 37, and the output from the second comparator 33 is delayed to output an output voltage (V_C3). Additionally, the output voltage (V_C3) is compared with a third reference voltage 38 by a third comparator 35 . The output of the third comparator 35 is input to the drive circuit 36 and converted to the drive signal Q1_Vgs.

2 and 4 show voltages at respective nodes of the second determination circuit 30 when a single-phase AC voltage is input. A full-wave rectified voltage obtained by rectifying a single-phase AC voltage by the full-wave rectifier circuit 5 becomes a pulsating current whose phase is almost 0 at 0° and 180°. A signal obtained by dividing this voltage by the voltage dividing circuit 31 composed of resistance elements also becomes a pulsating current as indicated by the divided voltage (V_R9) in FIGS.

By appropriately setting the second reference voltage 37 for the full-wave rectified voltage, when the divided voltage (V_R9) exceeds the second reference voltage 37, the output of the second comparator 33 (CMP2_V0 ) is high level, and the output (CMP2_V0) of the second comparator 33 can be low level when the divided voltage (V_R9) is below the second reference voltage 37 .

Here, by sufficiently increasing the time constant of the time constant circuit 34 in the next stage, the time constant circuit 34 is sufficiently It can be prevented that it is not charged, ie the output voltage does not rise. By setting this time constant, the output voltage of the time constant circuit 34 repeats charging and discharging within a range that does not rise to the third reference voltage 38 . Therefore, the output (CMP3_V0) of the third comparator 35 that compares the output voltage (V_C3) and the third reference voltage 38 is held at low level.

In this way, while the output (CMP3_V0) of the third comparator 35 is at low level, the driving signal (Q1_Vgs) output from the driving circuit 36 consisting of the resistive voltage dividing circuit is also held at low level. Therefore, the switching element Q1 arranged in the level adjusting section 11 of the level adjusting circuit 10 is always off, that is, the second resistance element R4 is open. determined only by

On the other hand, voltages at respective nodes of the second determination circuit 30 when a three-phase AC voltage is input are shown in FIGS. 3 and 5. FIG. The full-wave rectified voltage obtained by rectifying the three-phase AC voltage by the full-wave rectifier circuit 5 has a waveform substantially similar to that of the DC voltage. As shown in the divided voltage (V_R9) of FIGS. 3 and 5, the signal obtained by dividing this voltage by the voltage dividing circuit 31 made up of resistive elements also has a waveform similar to that of a DC voltage although a small amplitude oscillation remains. Become.

Here, it is essential that the second reference voltage 37 after the start-up of the internal auxiliary power supply is always set to be lower than the divided voltage (V_R9) when the three-phase AC voltage is input. In other words, since the divided voltage (V_R9) always exceeds the second reference voltage 37, the output (CMP2_V0) of the second comparator 33 can always be fixed at high level.

Since the time constant of the time constant circuit 34 in the next stage is set sufficiently large to handle the input of the single-phase AC voltage, its output voltage (V_C3) is always maintained at a high level. As a result, the output (CMP3_V0) of the third comparator 35, which compares the output voltage (V_C3) and the third reference voltage 38, can also always be at high level.

Since the output (CMP3_V0) of the third comparator 35 is always at high level, the drive signal (Q1_Vgs), which is the output of the drive circuit 36 consisting of the resistive voltage dividing circuit, is also maintained at high level. Therefore, the switching element Q1 arranged in the level adjustment section 11 of the level adjustment circuit 10 is always on, and the second resistance element R4 is connected in parallel with the first resistance element R3. is determined by the combined resistance value of the first resistance element R3 and the second resistance element R4.

In this manner, the second determination circuit 30 outputs a low-level voltage that turns off the switching element Q1 when a single-phase AC voltage is input, and outputs a switching element Q1 when a three-phase AC voltage is input. By outputting a high-level voltage that turns on the element Q1, it is possible to determine whether the input voltage is single-phase or three-phase.

On the other hand, determination of start or stop by the first determination circuit is determined by the voltage value of the detection level signal output from the level adjustment circuit 10 . The level adjustment circuit 10 also full-wave rectifies the AC input voltage, smoothes the rectified voltage so that it can be treated as a DC voltage, divides the voltage by resistors, and outputs it as a detection level signal.

These single-phase AC voltages are full-wave rectified and further smoothed to obtain a substantially DC voltage value, and a three-phase AC voltage having the same voltage value as the single-phase AC voltage is full-wave rectified and further smoothed. It is self-evident that the ratio between the voltage value that is approximately DC and the Therefore, by setting the electrical resistance values of the first resistance element R3 and the second resistance element R4 so as to cancel out the ratio of these DC voltage values, either the single-phase AC voltage or the three-phase AC voltage Even when input, the voltage of the same detection level signal can be output for the same effective value.

Therefore, it is possible to output a start signal or a stop signal for the same effective value regardless of whether a single-phase AC voltage or a three-phase AC voltage is input.

As described above, according to the embodiment of the present invention, regardless of whether a single-phase AC or a three-phase AC is input, the same input voltage value is used to determine whether to start or stop. A power supply that avoids malfunctions caused by different full-wave rectified voltages in single-phase AC and three-phase AC by observing the order of starting and stopping the auxiliary power supply and starting and stopping the power supply itself. It is something to do.

In addition, FIG. 2 shows the signal waveform at each node when a single-phase AC voltage with an effective value of 82 V is input to any two of the three input terminals U, V, and W, and the start signal is output. show. FIG. 3 shows signal waveforms at each node when a three-phase AC voltage with an effective value of 81 V is input to three input terminals U, V, and W and a start signal is output. In this manner, regardless of whether single-phase alternating current or three-phase alternating current is input, the activation signal is output when a voltage having the same effective value is input.

Further, FIG. 4 shows the signal waveform at each node when a single-phase AC voltage with an effective value of 70 V is input to any two of the three input terminals U, V, and W, and a stop signal is output. show. FIG. 5 shows signal waveforms at each node when a three-phase AC voltage with an effective value of 69 V is input to three input terminals U, V, and W and a stop signal is output. Thus, the stop signal is output when a voltage having the same effective value is input, regardless of whether single-phase alternating current or three-phase alternating current is input.

In addition, by applying the hysteresis circuit shown in FIG. 8 to the first comparator 26 and applying the hysteresis circuit shown in FIG. Or even if any of the three-phase AC is input, the effective value of the input voltage when outputting the start signal (approximately 80V) and the effective value of the input voltage when outputting the stop signal (approximately 70V) , and the difference can be the same.

Further, FIG. 6 shows waveforms at each node when a three-phase AC voltage is input and any one of the three phases is open while the power supply is operating. The second determination circuit 30 detects that there is an open phase, and the voltage of the detection level signal (V_R3) rises, but the operation of the power supply device can be continued.

FIG. 7 shows waveforms at each node when the above-mentioned open-phase phase becomes double-phase. The second determination circuit 30 detects the multiphase, and the voltage of the detection level signal (V_R3) returns to a predetermined value. This operation can also be performed while the power supply continues to operate.

REFERENCE SIGNS LIST 1 power supply 3 input rectifier 5 full-wave rectifier 10 level adjustment circuit 11 level adjustment 12 voltage divider 14 detection level signal supply line 20 first determination circuit 22 signal output terminal 25 first reference voltage 26 first voltage Comparator 28 Output circuit 30 Second determination circuit 31 Voltage dividing circuit 32 Drive signal supply line 33 Second comparator 34 Time constant circuit 35 Third comparator 36 Drive circuit 37 Second reference voltage 38 Third reference Voltage 40 Operating power supply 41 Operating voltage supply line U, V, W Input terminals

Claims (14)

three input terminals to which an alternating voltage is input;
a full-wave rectifier circuit connected to each of the three input terminals and outputting a full-wave rectified voltage of the AC voltage;
a level adjustment circuit that outputs a detection level signal obtained by dividing the full-wave rectified voltage;
a first determination circuit that receives the detection level signal and outputs a control signal based on the detection level signal;
a second determination circuit that outputs a drive signal based on the full-wave rectified voltage;
the level adjustment circuit adjusting the value of the detection level signal according to the drive signal;
The second determination circuit uses the full-wave rectified voltage to determine whether the AC voltage input to the three input terminals is single-phase AC or three-phase AC. . the level adjustment circuit includes a level adjustment section having one end connected to a ground potential;
2. The power supply according to claim 1, wherein said level adjustment section divides said full-wave rectified voltage between said full-wave rectifier circuit and said ground potential, and outputs said divided voltage as said detection level signal. Device. The level adjustment circuit has a variable resistance element whose resistance value changes according to the drive signal supplied from the second determination circuit, and changes the resistance value of the variable resistance element according to the drive signal, 3. The power supply device according to claim 2, wherein the value of said detection level signal is adjusted. The level adjustment section includes a first resistance element connected in series between the full-wave rectifier circuit and the ground potential, and an adjustment element connected in parallel to the first resistance element. 4. A power supply device according to claim 2 or 3 , wherein said adjustment element comprises a second resistance element and a switching element connected in series. 5. The power supply device according to claim 4 , wherein said switching element of said level adjusting section is turned on or off by said drive signal supplied from said second determination circuit. When the AC voltage input to the three input terminals is a three-phase AC voltage, the drive signal turns on the switching element of the level adjustment unit and is input to any two terminals of the three input terminals. 6. The power supply device according to claim 4 , wherein said switching element of said level adjusting section is turned off when the single-phase alternating current is supplied. 7. The switching element of the level control unit is turned off when the AC voltage input to the three input terminals is a three-phase AC, and one of the phases is open. power supply. 8. The power supply device according to claim 5, wherein when said switching element of said level adjusting section is in an ON state, the value of said detection level signal is lower than when said switching element is in an OFF state. . 9. The level adjustment circuit outputs the detection level signal of the same value for the same AC voltage regardless of whether the AC voltage to be input is a three-phase AC voltage or a single-phase AC voltage. The power supply device according to any one of Claims 1 to 3. The control signal output by the first determination circuit is either a start signal or a stop signal, and when the detection level signal exceeds a first reference voltage, the start signal is output and the detection level signal is output. 10. The power supply device according to any one of claims 2 to 9 , outputting said stop signal when V is below said first reference voltage. 11. The power supply device according to claim 2, wherein said level adjusting circuit further includes a voltage dividing section connected in series between said full-wave rectifying circuit and said level adjusting section. The first determination circuit includes a first comparator that compares the detection level signal and the first reference voltage, and an output circuit that converts an output of the first comparator into the control signal. 11. The power supply of claim 10 , comprising: The second determination circuit includes: a voltage dividing circuit that divides the full-wave rectified voltage; a second comparator that compares the divided full-wave rectified voltage with a second reference voltage; a time constant circuit that receives the output of the comparator; a third comparator that compares the output of the time constant circuit and a third reference voltage; and a drive signal that receives the output of the third comparator 13. The power supply device according to any one of claims 1 to 12 , comprising a drive circuit for outputting. 14. The power supply device according to claim 1, wherein each of said first determination circuit and said second determination circuit is driven by a common operating power supply voltage.

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