JPH0122399Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a control device for an inverter device for operating the inverter device in synchronization with a commercial power source.

Generally, a power supply device that switches and supplies power to the same load from a commercial power source and an inverter device is configured as shown in FIG. That is, in FIG. 1, output switches (static switches) 3 and 4 made of high-speed switches such as semiconductor devices are connected to the output ends of the commercial power supply 1 and the inverter device 2, respectively, and the output sides of these output switches 3 and 4 are connected in common. The power is normally supplied to the load 5 from the inverter 2 via the output switch 4. When performing maintenance or inspection on this inverter device 2, or in the event of an accident with the inverter device 2, the output switch 4 on the inverter side is cut off, and the output switch 3 on the commercial power source side is turned on to supply power from the commercial power source 1 to the load 5. ing.

In addition, when maintenance and inspection of the inverter device 2 is completed, or when the fault in the inverter device is restored, the commercial power supply side output switch 3 is shut off, the inverter side output switch 4 is made conductive, and power is supplied from the inverter device 2 to the load 5. I will do it.

In this way, when switching the power supply to the load 5 from the inverter device 2 to the commercial power source 1, or from the commercial power source 1 to the inverter device 2,
It is necessary to synchronize the inverter device 2 with the commercial power supply 1. For this reason, a control device 6 is provided that compares the outputs of the commercial power source 1 and the inverter device 2 and controls the inverter device 2 so as to synchronize the inverter device 2 with the commercial power source 1. This control device 6
In order to make the outputs of the commercial power supply 1 and the inverter device 2 the same frequency and the same phase, the output of the inverter device 2 is compared with the output of the switching device 10, which will be described later, to determine the same phase and frequency as the output of the switching device 10. A phase control unit (PLL) 7 that outputs a clock pulse of a high-precision oscillator 9 including a crystal oscillator, etc., which generates a high frequency wave, divides this high frequency wave with several stages of frequency dividers, and outputs a pulse at a final target frequency (for example, 60 Hz); and the output pulse of the synchronous waveform shaper 8. and a switching device 10 that switches the output pulses of the high-precision oscillator 9 and inputs them to the phase control section 7, and detects the output of the commercial power source 1 and detects when the voltage of the commercial power source 1 becomes overvoltage or undervoltage. Voltage detector 11 that outputs output pulses
, the output of commercial power supply 1 is detected and this commercial power supply 1 is
The frequency detector 12 outputs an output pulse when the frequency of the frequency changes abnormally, and the output pulses of the voltage detector 11 and frequency detector 12 described above are input, and the switch 10 is switched by the OR output thereof. The frequency detector 12 includes a frequency detection circuit 13 that detects the frequency of the commercial power supply 1 and outputs a pulse synchronized with that frequency, and a high-precision oscillation circuit using a crystal or the like. It is composed of a circuit 14 and a comparison circuit 15 that compares the respective output pulses of the frequency detection circuit 13 and the high precision oscillation circuit 14 and outputs a comparison output pulse when the output pulse of the frequency detection circuit 13 changes abnormally. has been done.

Note that the high-precision oscillator 9 divides the high-frequency pulse using several stages of frequency dividers to obtain a predetermined frequency, but when the frequency of the high-frequency pulse is high, the high-precision oscillator 9 performs free-running oscillation. However, only the clock pulses of the high-frequency pulses are out of phase with the commercial power supply, and the difference is very small.

In the above configuration, considering the case where the commercial power supply 1 is normal and the output of the inverter device 2 is being supplied to the load 5 via the output switch 4, the commercial power supply 1 is normal. The outputs of the voltage detector 11 and the frequency detector 12 are both at zero level, and no output appears in the OR circuit 16. Therefore, the switch 10 is connected to the synchronous waveform shaper 8 side, and the pulses of the synchronous waveform shaper 8 synchronized with the commercial power supply are inputted to the phase control section 7 via the switch 10. This phase control section 7 compares the output pulse of the synchronous waveform shaper 8 with the synchronous output pulse obtained by detecting the output of the inverter device 2, and
The inverter device 2 is controlled by outputting a clock pulse having the same phase and frequency as the commercial power source 1, and the inverter device 2 operates in synchronization with the commercial power source 1.

Next, if we consider the case where the voltage or frequency of the commercial power supply 1 becomes abnormal, the voltage abnormality is detected by the voltage detector 11, and the frequency abnormality is detected by the frequency detector 12. One or both of the detection output pulses are output and input to the OR circuit 16. As a result, OR circuit 16
output becomes high level, and the switch 10 is connected to the high precision oscillator 9 side. Therefore, the output pulse of the high precision oscillator 9 is input to the phase control section 7 along with the output of the inverter device 2, and this phase control section 7 outputs a clock pulse having the same phase and frequency as the output pulse of the high precision oscillator 9. Inverter device 2
The inverter device 2 is synchronously controlled by the high precision oscillator 9.

As described above, the inverter device 2 and the commercial power source 1 are synchronized, and if the voltage or frequency of the commercial power source 1 is abnormal, the inverter device 2 and the high-precision oscillator 9 are synchronized. However, the conventional device shown in FIG. 1 has a complicated circuit configuration and requires a frequency detector 12 including a high-precision oscillator 14, which has drawbacks such as an increase in the cost of the control device 6. Was.

This invention was made in view of the above points, and the purpose is to provide a control device for an inverter device that has a relatively simple circuit configuration and does not require a frequency detector, and to achieve this purpose. The control device for the inverter device of this invention includes a synchronous waveform shaper that detects the output of a commercial power source and outputs pulses synchronized with the commercial power source, and a synchronous waveform shaper that receives the output of the synchronous waveform shaper and generates a pulse that is synchronized with the commercial power source. When the frequency of the output pulse of the synchronous waveform shaper is normal, it is forcibly synchronized by this output pulse, and when the frequency of the output pulse of the synchronous waveform shaper is high or low, the high precision oscillator oscillates free-running, and the synchronous waveform shaper a phase error detector that derives an exclusive logic output by comparing the period of the output pulse of the oscillator with the synchronous output pulse of the high-precision oscillator; A switching device that switches the output of the high-precision oscillator, compares the output of this switching device with the output of the inverter device, and outputs a clock pulse with the same phase and frequency as the output of this switching device to switch the inverter device out of phase. and a phase control section for controlling.

Embodiments of this invention will be described in detail below with reference to the drawings.

FIG. 2 is a block diagram showing the construction of an apparatus according to an embodiment of this invention, and the same parts as in FIG. 1 are designated by the same reference numerals. In the figure, 1 is a commercial power supply, 2
is an inverter device, and these outputs are supplied to the same load 5 via output switches 3 and 4, respectively.

Further, 6 is a control device that controls the inverter device 2 so as to compare the outputs of the commercial power source 1 and the inverter device 2 and synchronize the inverter device 2 with the commercial power source 1. In order to make the outputs of the inverter device 2 the same frequency and the same phase, the output of the inverter device 2 is compared with the output of the switching device 10, which will be described later, and the output of the switching device 10,
That is, a phase control section 7 outputs a clock pulse having the same phase and frequency as the commercial power supply 1 in a normal state to control the phase of the inverter device 2, and a phase control section 7 detects the output of the commercial power supply 1 and outputs a pulse synchronized with the commercial power supply 1. The synchronous waveform shaper 8 oscillates at a high frequency, and this high frequency is divided by several stages of frequency dividers to output a pulse with a frequency very close to the frequency of the commercial power supply 1 and slightly lower, and A high-precision oscillator 9 including a crystal oscillator, etc., which is forcibly synchronized by receiving the pulse output b of the synchronous waveform shaper 8 when the frequency of the power supply is high, and free-running oscillation when the frequency of the commercial power supply is low; A voltage detector 11 that detects the output of the power supply 1 and outputs an output pulse when the voltage of the commercial power supply 1 becomes overvoltage or undervoltage.
, a phase error comparator 17 which inputs the output pulse e of the high-precision oscillator 9 and the output pulse c of the synchronous waveform shaper 8 and compares their periods, and the voltage detector 11 and phase error comparator 17 described above. An output pulse is input, and the OR output causes the switching device 10 to
The phase error comparator 17 is an exclusive OR gate whose gate inputs are the output pulse c of the synchronous waveform shaper 8 and the output pulse e of the high precision oscillator 9. 1
8, diode 19, resistor 20, capacitor 2
1, a resistor 22, and an amplifier 23.

Next, the operation of the control device 6 shown in FIG. 2 will be explained with reference to the signal waveform diagram of each part in FIG. 3.

Now the commercial power supply 1 is normal, and the frequency of the commercial power supply and the frequency of the high precision oscillator 9 are equal (very close)
If (t< of the waveform of the commercial power supply in Figure 3 a)
If we consider the case where power is being supplied from the inverter device 2 to the load 5 via the output switch 4, the voltage waveform of the commercial power supply 1 will be as shown in the interval t<t1 in Figure 3a. Since it is normal, the output of the voltage detector 11 is at zero level. On the other hand, the synchronous waveform shaper 8 detecting the output of the commercial power source 1 outputs an output pulse synchronized with the commercial power source 1 shown in FIG. 3b and a positive half-cycle pulse width of the commercial power source 1 shown in FIG. 3c. Outputs a square wave pulse with In addition, the frequency of the high-precision oscillator 9 is set to a value that is very close to the frequency of the commercial power supply 1 and slightly lower.
In addition, since the output pulse b of the synchronous waveform shaper 8 is input to the high-precision oscillator 9, it is forcibly synchronized by this pulse, and the pulse is synchronized with the commercial power supply 1 as shown in FIG. Output. Therefore, the inputs of the exclusive OR gate 18 are both at high level, the output of the gate 18 is at zero level, the output of the phase error detector 17 is zero, and the OR circuit 1
No output appears on 6. Therefore, the switch 10 is connected to the synchronous waveform shaper 8 side. Furthermore, as mentioned earlier, the synchronous waveform shaper 8 outputs a pulse c synchronized with the commercial power supply 1, and this output pulse c
is input to the phase control unit 7, which compares the output pulse c of the synchronous waveform shaper 8 and the output of the inverter device 2, and generates a clock pulse (output pulse) having the same phase and frequency as the commercial power supply 1. The inverter device 2 is operated in synchronization with the commercial power supply 1 by outputting a clock pulse (clock pulse synchronized with the clock pulse c) to control the inverter device 2.

Next, considering the case where the frequency of the commercial power supply 1 becomes lower than the normal frequency (in the section t>t1 in Fig. 3a), the synchronous waveform shaper 8 detecting the output of the commercial power supply 1 is Commercial power supply 1 shown in figure b
A pulse b synchronized with , and a rectangular pulse c having a pulse width of the positive half cycle of the commercial power supply 1 shown in FIG. 3c are output. In addition, since the frequency of the commercial power source 1 becomes lower than the regular frequency, the free-running oscillation frequency of the high-precision oscillator 9 becomes relatively higher than the frequency of the commercial power source 1, and the output pulses become as shown in Fig. 3 d and e. The output pulses are output from a position whose phase is more advanced than the output pulses b and c of the synchronous waveform shaper 8 as shown.
The falling position of this output pulse d is regulated by the pulse width determined by free-running oscillation from the position of pulse b, and the output pulse e has a synchronous waveform from the rising phase of the free-running oscillating pulse, as shown in Figure 3e. Forming machine 8
The pulse width is limited to the falling phase of the output pulse c. Therefore, since the pulses c and e in FIG. 3 are input to the exclusive OR gate 18, the gate output is in phase with the rising phase of the free-running oscillating pulse of the high-precision oscillator 9, as shown in FIG. 3f. The output of the gate 18 is charged by the capacitor 21 as shown in FIG.
The amplified output h is amplified by the OR circuit 16
is input. As a result, the output of the OR circuit 16 becomes high level, and the output connects the switch 10 to the high precision oscillator 9 side. Therefore, the output pulse d of the high-precision oscillator 9 is input to the phase control section 7 along with the output of the inverter device 2, and this phase control section 7 outputs a clock pulse having the same phase and frequency as the output pulse d of the high-precision oscillator 9. The inverter device 2 is controlled synchronously by the high-precision oscillator 9.

Also, if the frequency of the commercial power supply 1 becomes higher than the regular frequency and the period becomes shorter, the control device 6
Similarly, the inverter device 2 is connected to the high precision oscillator 9.
It can be operated in a controlled manner in synchronization with the output pulse of.

In this case, the signal waveforms of each part of the control device 6 shown in FIG. 2 become as shown in FIG. 4.

Considering the case where the frequency of the commercial power supply 1 becomes higher than the normal frequency (in the section t>t1 in Fig. 4a), the free-running oscillation frequency of the high-precision oscillator 9 becomes relatively higher than the frequency of the commercial power supply 1. getting lower,
The output pulses are output from positions delayed in phase from the output pulses b and c of the synchronous waveform shaper 8, as shown in FIGS. 4d and 4e. The falling position of this output pulse d is regulated by the pulse width determined by free-running oscillation from the position of pulse b, and the falling position of output pulse e is regulated by the synchronous waveform shaper 8 from the rising phase of the free-running oscillating pulse. It is regulated by the pulse width up to the falling phase of the output pulse c. Therefore, since the pulses c and e in FIG. 4 are input to the exclusive OR gate 18, the gate output is output from the high-precision oscillator 9 from the rise of the pulse synchronized with the commercial power supply 1, as shown in FIG. 4f. The output of the gate 18 is charged by the capacitor 21 as shown in FIG.
The amplified output h is amplified by the OR circuit 16
is input. As a result, the output of the OR circuit 16 becomes high level, and the output connects the switch 10 to the high precision oscillator 9 side.

Further, if the voltage of the commercial power supply 1 abnormally changes, the voltage detector 11 detects this state and outputs an output pulse to the OR circuit 16, and the output of the OR circuit 16 causes the switch 10 to switch to the high-precision oscillator 9 side. As in the case described above, the inverter device 2 is controlled in synchronization with the high precision oscillator 9.

As described above, the inverter device 2 and the commercial power source 1 are synchronized, and if the voltage or frequency of the commercial power source 1 is abnormal, the inverter device 2 and the high-precision oscillator 9 are synchronized. .

As described above, the control device of this invention does not require a frequency detector unlike the conventional one, so the circuit configuration can be simplified and the cost of the device can be reduced. Furthermore, since a high-precision oscillator using a crystal oscillator or the like is synchronized with the commercial power supply, there are advantages such as being able to switch the high-precision oscillator to free-running oscillation without causing any disturbance even in the event of an abnormality in the commercial power supply.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a conventional device, FIG. 2 is a block diagram showing the configuration of an embodiment of the device of this invention, and FIGS. 3 and 4 are signal waveform diagrams of each part to explain its operation. . 1...Commercial power supply, 2...Inverter device, 3,
4... Output switch, 5... Same load, 6... Control device, 7... Phase control unit, 8... Synchronous waveform shaper, 9... High precision oscillator, 10... Switch, 16
...Or gate, 17...Phase error detector, 18
...Exclusive OR gate.

Claims (1)

[Claims for Utility Model Registration] In a power supply device that supplies the output of a commercial power source and an inverter device to the same load through respective output switches, the output of the commercial power source is detected and the positive half of the commercial power source voltage is detected. A synchronous waveform shaper that generates a rectangular wave pulse with a pulse width of 1 cycle, and a high precision device that synchronizes the phase at the rising or falling edge of the rectangular wave pulse and generates a rectangular wave pulse at a normal commercial power frequency during free-running oscillation. an oscillator; a phase error detector that derives an exclusive logic output by comparing the period of the output pulse of the synchronous waveform shaper with the synchronous output pulse of the high-precision oscillator; A switching device that switches between the output of the waveform shaper and the output of the high-precision oscillator, and an output of the inverter device and the output of the switching device are compared, and a clock pulse having the same phase and frequency as the output of the switching device is generated. A control device for an inverter device, comprising: a phase control section that outputs a phase control section to control the phase of the inverter device.