JPH0526913Y2 - - Google Patents

Description

[Detailed description of the invention] The invention comprises an uninterruptible device, particularly a DC power supply and an inverter that converts the DC voltage from the DC power supply into an alternating voltage, and supplies the output voltage of the inverter to the load in the event of a commercial power outage. In this uninterruptible device, the frequency of the DA conversion in the inverter is controlled using a PLL that outputs a frequency signal synchronized with the frequency of the commercial power supply when the main DC voltage is not supplied. Therefore, the present invention relates to an uninterruptible device that prevents a phase difference from occurring in the output voltage when switching power sources due to a power outage of the commercial power source.

Generally, when receiving power from a commercial power supply, for example, an uninterruptible device that continues to supply power even in the event of a power outage uses an inverter to convert the DC voltage from the DC power supply to the above-mentioned commercial power frequency. 2. Description of the Related Art An uninterruptible device that continues to supply power to a load by switching to a power supply device that converts the voltage into an alternating voltage and outputs it is known.
However, depending on the type of load, problems may occur if the phase of the voltage waveform shifts during power supply switching due to a power outage of the commercial power supply. Further, the above-mentioned phase shift poses a problem when the inverter operates following the commercial power supply. Therefore, there is a strong demand for an uninterruptible device that can continue supplying power without causing deviations in voltage waveforms, at least when switching power sources due to power outages. Further, in order to eliminate the above-mentioned phase shift, it is not preferable to operate the inverter with the main DC voltage being supplied to the inverter before the power outage. In addition, even in the case of a configuration in which only the main DC voltage was supplied before the power outage (i.e., without applying a control signal to the inverter) and the control signal is applied at the time of a power outage, the main DC voltage is still being applied. There are maintenance difficulties.

The purpose of the present invention is to meet the above-mentioned demands, and by controlling the frequency in the DA conversion of the inverter using a PLL that generates a frequency signal synchronized with the frequency of the commercial power supply,
It is an object of the present invention to provide an uninterruptible device capable of continuously supplying a voltage with no phase shift in voltage waveform at least during a power outage and upon recovery. This will be explained below with reference to the drawings.

Figure 1 is a block diagram showing the configuration of an embodiment of the present invention, Figure 2 is a block diagram for explaining the configuration of the PLL shown in Figure 1, and Figure 3 explains the operation of the embodiment shown in Figure 1. It shows the time chart for In the figure, 1 is an input terminal that is connected to a commercial power supply, 2 is an output terminal, and 3 is a voltage detection section that detects the commercial power supply voltage and is used as an AC
Those that output control signals for switching elements, DC switching elements, etc. 4 to 6 are AC
Switch element, 7 is frequency detection section, 8 is PLL,
Reference numeral 9 denotes a DC power supply section, 9a to 9c are terminals, where terminal 9a is connected to a battery power supply;
A starting signal for an engine-driven generator (not shown) is outputted to a terminal b, and an output voltage of the engine-driven generator is supplied to a terminal 9c. Furthermore, 10 and 11 are knot gates, and 12 is
DC switching element, 13 is an automatic voltage regulator,
14 is a voltage detection section, 15 is a rectification section, 16 is a smoothing circuit, 17 is an inverter, 18 is a commercial frequency reference signal generation section, 19 is a standard frequency reference signal generation section, 2
0 represents a phase detection section, and 21 represents a voltage controlled oscillator.

The operation of the embodiment of the present invention shown in FIG. 1 will be explained with reference to FIGS. 2 and 3. In FIG. 1, when a commercial frequency power supply voltage (hereinafter referred to as commercial voltage) is supplied to the input terminal 1, the voltage detection unit 3 detects the commercial voltage.
A gate signal for the AC switching element 4 is output. That is, when the AC switching element 4 is turned on, the commercial voltage is supplied from the output terminal 2 to the load. Under this condition, the knot
Since gates 10 and 11 are created,
AC switching element 5, DC switching element 1
2 is not turned on, and it goes without saying that the starting signal for the engine drive generator (not shown) is not output from the terminal 9b. Further, the frequency of the commercial voltage is detected by the frequency detection section 7, and information corresponding to the frequency is transmitted to the PLL.
Sent to 8th. Based on the information, the PLL 8 outputs a frequency control signal synchronized with the frequency of the commercial voltage. Here, the operation of the PLL 8 will be explained with reference to FIGS. 2 and 3. That is, based on the frequency information sent from the frequency detection section 7, the third
A commercial reference signal as illustrated in Figure b is generated. Then, a control signal as shown in FIG. 3d corresponding to the frequency of the commercial voltage is outputted from the voltage controlled oscillator 21 via the phase detection section 20. In this case, even if the frequency of the commercial voltage changes, for example, the output of the voltage controlled oscillator 21 is fed back to the phase detection section 20, so that the control as shown in FIG. The signal follows the frequency of the commercial voltage, but at this time, the control signal output from the voltage controlled oscillator 21 does not change suddenly, but gradually changes and becomes synchronized with the frequency of the commercial voltage. . Further, the standard frequency reference signal (hereinafter referred to as standard reference signal) generating section 19 generates a standard reference signal corresponding to a predetermined frequency as shown in FIG. 3c, for example. Note that the standard reference signal is sent to the phase detection section 20 only when the commercial reference signal is stopped.

As explained above, while the commercial voltage is being supplied, the gate of the inverter 17 is controlled in synchronization with the frequency of the commercial voltage. That is, as shown in FIG. 3, assuming that the commercial voltage shown in the diagram a is supplied until time _t1 , the control signal output from the PLL 8 corresponds to the waveform of the commercial voltage as shown in the diagram d. It becomes what it is. That is, inverter 1
For example, the anode of the thyristor composing the thyristor 7 is in a state where no DC voltage is applied to its anode, but the gate is supplied with the above control signal and is ready to generate a replacement output at any time. The output voltage from output terminal 2 is as shown in the figure e.
Needless to say, the above-mentioned commercial voltage is output as is through the AC switching element 4.

Next, assuming that the supply of the commercial voltage is stopped at, for example, time _t1 shown in FIG. 3, the operation of the embodiment shown in FIG. ₁ after time t1 will be described. When the commercial voltage is stopped, the output signal from the voltage detection section 3 goes to the "0" level, so the outputs of the not gates 10 and 11 go to the "1" level. Therefore, the AC switching element 4 is turned off, and the AC switching element 5 and the DC switching element 12 are turned on. Therefore, the DC voltage of the battery (not shown) is the same as that of the automatic voltage regulator 1.
3. The voltage is guided to the inverter 17 via the smoothing circuit 16, where it is immediately converted to an alternating voltage and supplied to the load via the AC switching element 5 and the output terminal 2. Also, terminal 9b
A start signal to the engine-driven generator (not shown) is output from the engine, and the engine-driven generator starts operating. Then, when the output voltage of the engine-driven generator reaches a predetermined voltage value, the voltage detection section 14 outputs a gate signal to the AC switching element 6, thereby turning on the AC switching element 6. This time is the time shown in Figure 3.
Assuming t ₂ , from time t ₂ onward, the output voltage of the engine-driven generator is converted to a DC voltage by the rectifier 15, and further converted to an alternating voltage by the inverter 17, which is then supplied to the load. . _After the above time t1, as the supply of commercial voltage is stopped, the commercial reference signal to the phase detection section 20 (shown in FIG. 2) in the PLL 8 stops as shown in FIG. 3b, and as shown in FIG. A standard reference signal is derived as shown in c. At this time, the above
As mentioned above, the control signal output from PLL8 is synchronized with the frequency of the commercial voltage immediately before the power outage, and for example, as shown in FIG. Even if a phase difference of φ ₁ exists in the inverter 17
There is no phase shift in the output voltage at the above time _t1 . As described above, the phase of the control signal output from the PLL 8 gradually changes and becomes synchronized with the standard reference signal after a predetermined period of time has elapsed. This state is illustrated in FIG. 3, in which the control signal and the standard reference signal are shown to be synchronized approximately two cycles after the time _t1 , but for convenience of explanation, the control signal and the standard reference signal are shown as being synchronized. It is merely a representation.

Further, for example, if the commercial voltage is restored at time t3 shown in FIG. ₃ , the commercial reference signal is restored and the standard reference signal is stopped after time _t3 . However, the inverter 17 at the above time _t3
The frequency of the output voltage is synchronized with the standard reference signal, for example as shown in FIG.
Even if there is a phase difference of φ ₂ between the control signal and the commercial reference signal, the output voltage of the inverter 17 will not have a phase shift at time t ₃ . As described above, the phase of the control signal output from the PLL 8 gradually changes and becomes synchronized with the commercial reference signal after a predetermined period of time has elapsed. That is, after a predetermined period of time has elapsed, the phases of the output voltage of the inverter 17 and the already restored commercial voltage become synchronized. Note that the voltage detection unit 3 described above is equipped with a delay function (not shown), and suspends the output of the gate signal until time _t4 , when the predetermined time has elapsed after the detection of the commercial voltage, so that the voltage is not supplied to the load. The voltage applied is the output voltage of the inverter 17. Then, the time after the phase of the output voltage of the inverter 17 and the commercial voltage is synchronized.
Since AC switching elements 4 and 5 are switched at t ₄ , no phase shift occurs in the output voltage at the time of switching.

As explained above, according to the present invention, it is possible to continuously supply a load with a voltage that does not cause a phase shift with the voltage waveform of the commercial power supply at least when switching the power supply during a commercial power outage. Uninterruptible equipment can be provided. Further, there is no need to apply the main DC voltage to the inverter so that the inverter is operated in a so-called no-load state in advance.

[Brief explanation of drawings]

Figure 1 is a block diagram showing the configuration of an embodiment of the present invention, Figure 2 is a block diagram for explaining the configuration of the PLL shown in Figure 1, and Figure 3 explains the operation of the embodiment shown in Figure 1. Show the time chart for. In the figure, 1 is an input terminal, 2 is an output terminal, 3 and 14 are voltage detection sections, 4 to 6 are AC switching elements, 7 is a frequency detection section, 8 is a PLL, 9 is a DC power supply section, and 10 and 11 are notes.・Gate, 1
2 is a DC switching element, 13 is an automatic voltage regulator, 15 is a rectifier, 16 is a smoothing circuit, 17 is an inverter, 18 is a commercial frequency reference signal generator, 19
20 represents a standard frequency reference signal generator, 20 represents a phase detector, and 21 represents a voltage controlled oscillator.

Claims (1)

[Scope of claim for utility model registration] A main AC switch that supplies power from a commercial power source to a load, an auxiliary power source that generates DC voltage, a battery that operates before the auxiliary power source is turned on, and a connection between the auxiliary power source and the battery. An inverter that converts the DC voltage supplied from either to an alternating voltage;
Auxiliary to supply the output voltage of the inverter to the load
An AC switch and a commercial voltage detection unit that detects the voltage of the commercial power supply are provided, and the main AC switch and the auxiliary AC switch are exclusively controlled based on the detection signal of the commercial voltage detection unit. In an uninterruptible device that supplies DC voltage from the battery or the auxiliary power supply to a load with the output voltage of the inverter during a commercial power outage, the frequency detection unit detects the frequency of the commercial power supply; A PLL that generates frequency information synchronized with the output signal of the PLL is provided, and even before the commercial power supply fails, the frequency signal from the PLL is is applied as a control signal for the inverter, and when voltage detection from the commercial voltage detection section stops, starts the auxiliary power supply and turns on the DC switch that supplies the DC voltage from the battery to the inverter. The output frequency of the inverter is controlled based on the frequency signal from the PLL to supply power to the load, and when the commercial power supply fails, the output voltage from the battery is initially set to the level above. An uninterruptible device characterized in that a state is created in which a main DC voltage is supplied to an inverter, and then an output voltage from the auxiliary power source is supplied as a main current voltage to the inverter.