JPH05176553A - Inverter control method of non-interruption power supply apparatus and non-interruption power supply apparatus - Google Patents

Abstract

PURPOSE:To improve the utilization factor of a DC voltage by a method wherein a modulation method with a third harmonic, etc., is applied to a non-interruption power supply apparatus whose phase voltages are controlled by the feedback of the phase voltages detected from line voltages. CONSTITUTION:The line voltages of the output voltages of an inverter 2 are detected by a voltage transformer 6 and the respective phase voltages are obtained by a converting circuit 7. Phase voltage control signals corresponding to the deviations between the detected phase voltage values and command sine wave phase voltages are generated by voltage control circuits 8u, 8v and 8w. Further, in order to modulate predetermined carrier waves by modulating circuits 11u, 11v and 11w with the phase voltage control signals as modulation waves to generator PWM pulses for driving the switching devices of the inverter 2, a negative side envelope signal generating circuit 15 which superposes signals corresponding to negative envelopes related to three-phase waveforms of the command sine wave voltages or the phase voltage control signals on the modulation waves is provided. Instead of superposing the negative side envelope signals on the modulation waves, the third harmonics of the command phase voltages may be superposed on the modulation waves.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter control method for a three-phase uninterruptible power supply and an uninterruptible power supply.

[0002]

2. Description of the Related Art Generally, an uninterruptible power supply system is a DC power supply composed of a rectifier for rectifying AC power of a commercial power supply and a capacitor for storing a certain amount of DC power of its output, and a DC power of this DC power supply. And an inverter of a pulse width modulation (PWM) system for converting into AC power of voltage / frequency.

In such an uninterruptible power supply, a sine wave having a constant voltage and a constant frequency is applied to a load such as an information processing device even if voltage fluctuation, waveform distortion, momentary power failure, etc. occur in a commercial power supply. It is required to supply the AC voltage. Therefore, conventionally, the instantaneous value of the output voltage is feedback-controlled to accurately and stably control the output voltage. That is, the voltage command value of each phase of the inverter is set to a sine wave, the output voltage of each phase of the inverter output is detected, and the sine wave control signal corrected so as to cancel the deviation is used as a modulation wave by the PWM control of the inverter. To drive.

On the other hand, a three-phase PW used for driving a motor
In the M inverter, a trapezoidal wave modulation method in which the voltage command value of each phase of the inverter is a trapezoidal wave on condition that the line voltage of the output voltage is held in a sine wave in order to improve the utilization factor of the DC voltage. , Or PWM with a modulation wave that superimposes the triple harmonic wave that is canceled by the line voltage on the voltage command value of the sine wave
A modulation method is adopted. According to the trapezoidal wave modulation method and the method of modulating by superimposing the triple harmonic wave, the voltage utilization rate is about 15% as compared with the case of the simple sine wave modulation method.
It is known to improve.

[0005]

However, in the uninterruptible power supply device, the line voltage of the inverter output is first detected by using the voltage transformer to detect the output voltage, and the detected line voltage is converted into the phase voltage. Since it is converted and fed back, even if a voltage command value in which a trapezoidal wave or a triple harmonic is superimposed on the phase voltage command of the inverter is used, the fed back phase voltage detection value is a trapezoidal wave or 3 The harmonics are canceled out and become a sine wave. Therefore, there is a problem that the phase voltage command value that is trapezoidal wave modulation or triple harmonic modulation does not match the feedback value. Therefore, the conventional trapezoidal wave modulation method or triple harmonic wave is superimposed on the UPS. There is a problem that the modulation method cannot be applied as it is and the use efficiency of the DC voltage cannot be improved.

An object of the present invention is to perform phase voltage control using a control signal having a trapezoidal wave or a triple harmonic as a modulation wave even if the feedback voltage is a phase voltage obtained by detecting and converting a line voltage. An object of the present invention is to provide an inverter control method for an uninterruptible power supply capable of improving the utilization rate of a DC voltage and an uninterruptible power supply using the method.

Further, an object of the present invention is to make it possible to directly detect the phase voltage of the inverter output, apply a modulation method in which trapezoidal wave modulation or triple harmonics are superposed to make feedback control possible, and use the DC voltage. It is to provide an uninterruptible power supply which can improve the

[0008]

In order to achieve the above object, an inverter control method for an uninterruptible power supply of the present invention comprises:
The line voltage of the inverter output voltage is detected to detect the phase voltage of each phase, and the phase voltage control signal corresponding to the deviation between the detected phase voltage value and the phase voltage command value of the sine wave is used as the modulation wave. In an inverter control method for an uninterruptible power supply device, which modulates a carrier wave to generate a PWM pulse and ON / OFF controls a switching element of the inverter according to the PWM pulse, a phase voltage command value of a sine wave and the phase voltage control It is characterized in that a signal corresponding to a negative side envelope relating to a waveform of one of the three phases of the signal is superimposed on the modulated wave.

Further, in order to achieve the above object, the uninterruptible power supply device of the present invention comprises an inverter having a switching element connected in a three-phase bridge connection and converting DC power into AC.
A voltage transformer connected to the output of the inverter, a conversion circuit for converting the line voltage detected by the voltage transformer into a phase voltage, a phase voltage detection value output from the conversion circuit, and a sine wave phase A voltage control circuit that obtains a deviation from a voltage command value, and generates and outputs a phase voltage control signal having a value according to the deviation,
A modulation circuit that modulates a predetermined carrier wave by using the phase voltage control signal as a modulation wave and outputs a PWM pulse, and a switching control circuit that controls ON / OFF of a switching element of the inverter according to the PWM pulse output from the modulation circuit. In the uninterruptible power supply device comprising: a negative side for generating a signal corresponding to a negative side envelope curve related to a waveform for three phases of one of the phase voltage command value of the sine wave and the phase voltage control signal. An envelope signal generation circuit is provided, and an adder circuit that superimposes a signal corresponding to the negative envelope on the modulated wave is provided in the modulation circuit.

Further, instead of superposing the negative envelope signal on the modulated wave, a harmonic signal generating circuit for generating a triple harmonic of the phase voltage command value of the sine wave is provided, and the harmonic signal thereof is generated. The triple harmonic signal generated by the signal generating circuit may be superimposed on the modulated wave. It is preferable to multiply the modulated wave by a coefficient of 1 or less in both cases of superimposing the negative side envelope and superimposing the triple harmonic.

Further, in order to achieve another object of the present invention,
The uninterruptible power supply device of the present invention has an inverter that has a switching element connected in a three-phase bridge and converts DC power to AC, a capacitor series connection circuit that divides the DC voltage of the inverter, and a phase voltage of the inverter. A phase voltage command value generating circuit for generating a phase voltage command value obtained by distorting a target waveform into a trapezoidal wave or a phase voltage command value with a triple harmonic superimposed, a neutral point of the capacitor series connection circuit and the inverter Voltage control for obtaining a deviation between a phase voltage detection value obtained by detecting a voltage between the alternating-current portion of each phase and the phase voltage command value, and generating and outputting a phase voltage control signal having a value according to the deviation A circuit, a modulation circuit that outputs a PWM pulse by modulating a predetermined carrier wave using the phase voltage control signal as a modulation wave, and a switching element of the inverter according to the PWM pulse output from the modulation circuit. The characterized by configured by including a switching control circuit for on-off control.

[0012]

According to the present invention having the above-mentioned structure, the above-mentioned object can be achieved by the following operations. That is, in the present invention, the signal corresponding to the negative side envelope relating to the waveform of one of the three phases of the sine wave phase voltage command value and the phase voltage control signal is the phase voltage command value or the phase voltage control signal. It is a triple harmonic. The carrier wave is modulated by the modulation wave obtained by adding the negative side envelope signal to the phase voltage control signal, that is, P
Since the PWM pulse is generated by the WM control and the switching control of the inverter is performed using this,
The utilization rate of DC voltage can be increased. Therefore, the command value for controlling the instantaneous value of the phase voltage may be a sine wave, and the phase voltage fed back to the voltage control circuit may be a sine wave.Therefore, the sine wave phase voltage obtained by conversion from the line voltage is fed back. Can control the instantaneous voltage,
Even in an uninterruptible power supply that cannot directly detect the phase voltage,
The utilization rate of the DC voltage can be increased by applying the modulation method in which the triple harmonic is superimposed.

Further, instead of superimposing the negative envelope signal on the modulated wave, a harmonic signal generating circuit for generating a triple harmonic of the phase voltage command value of the sine wave is provided, and the harmonic signal thereof is generated. The same applies when the triple harmonic signal generated by the signal generating circuit is superimposed on the modulated wave.

By the way, in the case of the modulated wave in which the polarity inversion signal of the negative side envelope signal is superimposed, the peak value of the valley of the carrier composed of the triangular wave or the sawtooth wave coincides with the zero line of the modulated wave. Or, when the level becomes lower than the zero line, switching is performed when the switching should be paused, which increases switching loss.

In order to solve such a problem, a minute positive offset component as shown in FIG. 5 (a) is added to the carrier wave, and the peak value of the valley of the carrier wave is the modulated wave. It is considered that it is possible to prevent the increase of switching loss by preventing it from matching the zero line of. However, if the carrier wave is offset to the positive side, the actual modulation period becomes narrower than the modulation period T1 to be modulated as shown in FIG. 5A, that is, T2, and PWM modulation cannot be performed during the period. Therefore, as shown in FIG.
For example, distortion occurs in the voltage waveform of the output voltage euv. Therefore, the gain inversion circuit multiplies the polarity inversion signal ep of the negative side envelope signal by a coefficient of "1" or less to change the level, and as shown in FIG. By performing the PWM modulation in the entire period to be biased, the output voltage waveform without distortion is obtained as shown in FIG. 5D.

According to another aspect of the present invention, since the capacitor series connection circuit for dividing the voltage of the DC part of the inverter is provided, the neutral point of the capacitor series connection circuit and the AC part of each phase of the inverter are provided. The phase voltage can be directly detected by detecting the voltage between and. Therefore, the detected value of the phase voltage is fed back even if the phase voltage command value is obtained by distorting the target waveform of the phase voltage into a trapezoidal waveform or the phase voltage command value obtained by superimposing the triple harmonic. The voltage utilization factor can be improved without using the negative side envelope signal generating circuit or the like as described above.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to illustrated embodiments. 1 and 2 are block diagrams of an uninterruptible power supply according to a first embodiment of the present invention. As shown in FIG. 1, the main circuit of the uninterruptible power supply includes a DC power supply 1 including a converter and a capacitor, a three-phase inverter 2, a filter 3, and a transformer 4, and a load. 5 is supplied with three-phase AC power. The control device of the uninterruptible power supply converts the output line voltage of the transformer 4 into a predetermined level by the voltage transformer 6, converts the line voltage detection value into a phase voltage detection value in the conversion circuit 7, and In the voltage control circuit 8 (u, v, w) provided corresponding to each of the three phases in order to remove the deviation between the detected phase voltage value and the phase voltage command value of each phase, the phase of the inverter 2 The voltage control signals eu, ev, ew are generated, and the modulation circuit 11 (u, v, w) modulates a carrier wave such as a triangular wave to generate a PWM pulse.
Based on this PWM pulse, the switching control circuit 14
Thus, each switching element of the inverter 2 is driven. In addition, the modulation circuit 11 (u, v, w) includes a negative-side envelope signal generation circuit 1 according to a feature of the present invention.
The polarity inversion signal ep of the negative-side envelope signal of the phase voltage control signals eu, ev, and ew created in 5 is input, and the phase voltage control signals eu, ev, e before modulation of the envelope signal are input.
It is designed to be superimposed on w.

Although a transistor is used as the switching element of the inverter 2 in the figure, the invention is not limited to this, and other semiconductor switching elements such as a thyristor and a GTO thyristor may be used.

Next, referring to FIG. 2, the voltage control circuit 8
The configurations of (u, v, w) and the modulation circuit 11 (u, v, w) will be described. Since the circuits 8 and 11 have the same configuration for each phase, only one phase is shown in the figure for simplification of the figure. As shown in the figure, the voltage control circuit 8 includes a control operation circuit 82 and a subtraction circuit 83. The subtraction circuit 83 calculates the deviation of the instantaneous value between the sine wave phase voltage command value Uref (Vref, Wref) input from the phase voltage command value generation circuit 9 and the phase voltage detection value output from the conversion circuit 7. The control arithmetic circuit 82 is configured to obtain and output a sinusoidal phase voltage control signal eu (ev, ew) by proportional-plus-integral control or the like in order to make the deviation of the instantaneous value zero. The modulation circuit 11 generates a carrier wave ec such as a triangular wave or a sawtooth wave, and a negative side envelope signal generation circuit 1 for the phase voltage control signal eu output from the control arithmetic circuit 82.
5, an adder circuit 113 for adding the polarity inversion signal ep of the negative envelope signal output from the comparator 5, and a comparator circuit 1 for modulating the carrier wave ec by the output signal eu 'of the adder circuit 113.
And 12 are included.

The operation of the embodiment thus constructed will be described. 3 (a) to 3 (e) are operation waveform diagrams of each part.
FIG. 10A shows waveforms of the phase voltage control signals eu, ev, ew output from the voltage control circuits 8u, 8v, 8w.
(B) shows the carrier wave ec and the modulated waves eu 'and ev'.
(C) is a pulse of the U-phase inverter output voltage Eu,
(D) shows a pulse of the V-phase inverter output voltage Ev, and (e) shows a pulse of the output line voltage Vuv. In the figure, only the output line voltage Vuv output by the U phase and the V phase is shown, and the output voltage Ew of the W phase is omitted.

The phase voltage control signals eu, ev, ew of FIG. 3 (a), which have been arithmetically processed by the voltage control circuits 8u to 8w based on the deviation between the command value and the detected value of the phase voltage, are the negative envelope signals. When it is input to the creation circuit 15, the circuit 15 outputs the data shown in FIG.
The polarity inversion signal ep of the negative envelope signal shown by the dotted line in (a)
Is output. A polarity inversion signal ep of this negative side envelope signal
Is added to the output signal eu (ev, ew) from the voltage control circuit 8 in the adder circuit 113, and is input to the comparison circuit 112 as the modulated wave eu ′ (ev ′, ew ′) shown in FIG. 3B. It In the comparison circuit 112, the modulated wave eu ′ (ev
′, Ew ′) is compared with the carrier wave ec, and a PWM pulse is output. As a result, the switching control circuit 14 operates, and the U-phase pulse and the V-phase pulse shown in FIGS. 3C and 3D are output. As a result, the output voltage Vuv of the inverter 2 becomes as shown in (e), and the output line voltage euv of the transformer 4 is obtained.

As described above, the polarity reversal signal ep of the negative side envelope signal obtained from the three-phase phase voltage control signals eu, ev, and ew in this embodiment is the third harmonic of the phase voltage control signal. ing. Then, the polarity reversal signal ep of the negative side envelope signal is added to the output signal eu (ev, ew) of the voltage control circuit 8 which performs the instantaneous voltage control, and the modulated wave eu '(ev', e) is obtained.
w ′) is generated and the switching control of the inverter 2 is performed using the PWM pulse generated based on this, so that the utilization rate of the DC voltage can be increased. Therefore, the command value for the instantaneous value control of the phase voltage may be a sine wave, and the phase voltage fed back to the voltage control circuit 8 may be a sine wave. Therefore, the sine wave phase voltage obtained by conversion from the line voltage is fed back. Then, the instantaneous voltage can be controlled. That is, even in the uninterruptible power supply device that cannot directly detect the phase voltage, the modulation method in which the triple harmonic is superimposed can be applied, so that the utilization rate of the DC voltage can be increased.

Further, according to the present embodiment, as shown in FIG. 3 (b), switching of the switching element of each phase of the inverter 2 is suspended for 1/3 cycle. This reduces switching losses.

FIG. 4 shows another embodiment of the modulation circuit 15. The present embodiment is different from the embodiment in FIG. 2 in that a gain multiplication circuit 114 for adjusting the gain K of the polarity inversion signal ep of the negative envelope signal is provided. That is, according to the embodiment of FIG. 2, as shown in FIG. 3B, the peak value of the valley of the carrier wave ec coincides with the zero line of the modulated waves eu ', ev', ew ', or the carrier wave If the peak value of the valley of ec becomes more negative than the zero line of the modulated waves eu ', ev', and ew ', the switching will be performed when the switching should be stopped, so that the switching loss increases. Become.

The present embodiment solves such a problem. As an example, first, the carrier wave generation circuit 111
As shown in FIG. 5 (a), an offset component is added to the carrier wave ec output from the carrier wave ec so that the peak value of the valley of the carrier wave ec does not coincide with the zero line of the modulated waves eu ', ev', ew '. It is possible to do it. However, when the carrier wave ec is offset, the actual modulation period becomes narrower than the modulation period T1 to be modulated as shown in FIG. 5A, that is, T2, and PWM modulation cannot be performed during the period. Therefore, as shown in FIG. 5B, for example, distortion occurs in the voltage waveform of the output voltage euv. Therefore, the polarity inversion signal ep of the negative envelope signal is output by the gain multiplication circuit 114.
Is multiplied by a coefficient K of "1" or less to change the level, and as shown in FIG. 5C, the modulated waves eu ', ev', ew '
Are aligned so as to coincide with the peak of the valley of the carrier wave ec. That is, the adder 113 when the coefficient K is not multiplied
Is eu '= (-ep polarity inversion signal) + eu, and its zero level theoretically corresponds to the peak value of the valley of the carrier wave ec. However, because of the above problems,
Multiply by a coefficient K smaller than “1”, and eu ′ = K · (−ep
5 (c) by setting the polarity reversal signal of the above) + eu, and the peak of the valley of the carrier wave ec is finely adjusted to the position of the intersection of eu ′ and ew ′. As a result, PWM modulation is performed during the entire period to be modulated, and as shown in FIG. 5D, an output voltage waveform without distortion can be obtained.

FIG. 6 shows a block diagram of another embodiment of the present invention. This embodiment is different from the embodiment of FIG. 1 in that the polarity inversion signal ep of the negative envelope signal is a sine wave phase voltage control signal e.
Instead of u, ev, ew, phase voltage command values Uref, Vref,
The point is that it is generated from Wref. That is, the negative side envelope signal generating circuit 16 has the phase voltage command values Uref and Vre.
f and Wref are input, the polarity inversion signal ep of the negative envelope signal of these command values is generated, and is output to each of the modulation circuits 11u to 11w. FIG. 7 shows the configuration of one phase of the voltage control circuit 8 and the modulation circuit 11 in the embodiment of FIG. In the figure, the same parts as those in FIG. 3 are designated by the same reference numerals and the description thereof will be omitted. According to this embodiment, the same effect as that of the embodiment of FIG. 3 is obtained.

FIG. 8 shows the configuration of still another embodiment of the present invention. The present embodiment differs from the embodiment of FIG. 1 in that instead of the negative side envelope signal generating circuit 15, a harmonic signal generating circuit 17 generates a triple harmonic signal 3f of the frequency of the phase voltage command value. The triple harmonic signal is superimposed on the sine wave phase voltage control signals eu, ev, ew by the modulation circuits 11u to 11w to obtain the modulated wave eu.
This is because ', ev', and ew 'are generated.
FIG. 9 shows the configuration of one phase of the voltage control circuit 8 and the modulation circuit 11. The same parts as those of the embodiment of FIG. 3 are designated by the same reference numerals and the description thereof will be omitted. That is, also in the present embodiment, similarly to the above-described embodiment, the harmonic signal generation circuit 17 generates a signal of a triple harmonic wave, and the gain multiplication circuit 114 adjusts the level of the signal, thereby performing instantaneous voltage control. Voltage control circuit 8
Are added to the phase voltage control signals eu, ev, ew which are the outputs of the above, and the carrier wave ec is modulated by using this as a modulating wave. Therefore, the voltage utilization rate is improved similarly to the above-described embodiment, the DC power source can be efficiently used, and the three-phase power having a waveform without distortion can be stably supplied to the load. Also,
The switching loss of the inverter 2 can also be reduced.

FIGS. 10, 11 and 12 show the configuration of another embodiment of the present invention. This embodiment is an example applied to an uninterruptible power supply system having a configuration in which electric power is directly supplied from a filter 3 to a load 5 without a transformer as shown in FIG. A series connection circuit of capacitors 18 and 19 is connected. In this case, since the series connection point of the capacitors 18 and 19 becomes the potential of the neutral point N of the AC part voltage, for example, among the output lines of the inverter 2, the connection point A1 or the connection point A2 and the neutral point in the figure are shown. From the voltage between N and N, the phase voltage to be fed back can be directly detected without using the line voltage. Therefore, the method of using a trapezoidal wave for the phase voltage command value or the method of superimposing the triple harmonic on the phase voltage command value can be applied as it is, and an uninterruptible power supply device with an improved DC voltage utilization rate can be realized. The configuration of the phase voltage command value generation circuit 9, the voltage control circuit 8 and the modulation circuit 11 of this embodiment is shown in FIG.
And shown in FIG.

FIG. 11 shows one of the phase voltage command value generation circuit 9, the voltage control circuit 8 and the modulation circuit 11 when the feedback phase voltage is detected between the neutral point N and the connection point A1. The composition of phases is shown. In the figure, a phase voltage command value generation circuit 20 generates a phase voltage command value Uref '(Vref', Wref ') in which a triple harmonic is superimposed on a trapezoidal wave or a sine wave. The voltage control circuit 8 is composed of a control calculation circuit 82 configured by a proportional integration circuit or the like for performing instantaneous voltage control, and a subtraction circuit 83 for obtaining a deviation between a phase voltage command value and a phase voltage detection value. Further, the modulation circuit 11 is a carrier generation circuit 111.
And a comparison circuit 112. Since the phase voltage is directly detected in this way, it is possible to perform feedback control in which the phase voltage detection value, which is a feedback signal, and the phase voltage command value Uref ′ superposed with a trapezoidal wave or a triple harmonic are directly matched. ..

FIG. 12 shows the structure of one phase of the voltage control circuit 8 and the modulation circuit 11 when the detected feedback phase voltage value is between the neutral point N and the connection point A2. 11 is different from FIG. 11 in that the voltage control circuit 8 is provided with a filter 84 for removing a noise component such as switching noise included in the phase voltage detection value. Other operations are the same as those in FIG. Is the same as

According to the embodiments shown in FIGS. 10 to 12, the phase voltage can be directly detected without converting the phase voltage from the line voltage by conversion. Therefore, the phase voltage detection value and the trapezoidal wave or the triple harmonic wave are superimposed. Feedback control that directly matches the phase voltage command value Uref 'becomes possible. Therefore, the voltage utilization rate of the DC voltage is improved, and the DC power supply can be efficiently used.

Further, the capacitors 18 and 1 of the embodiment of FIG.
The method of directly detecting the phase voltage by using 9 is also applicable to the case of the uninterruptible power supply device including the transformer 4 shown in the embodiment of FIG.

[0033]

As described above, according to the present invention,
The following effects are obtained. The signal corresponding to the negative envelope is the triple harmonic of the phase voltage command value or the phase voltage control signal. Then, since the switching control of the inverter is performed by the PWM pulse obtained by modulating the carrier wave with the phase voltage control signal obtained by adding this, the utilization rate of the DC voltage can be increased. Therefore, the command value for controlling the instantaneous value of the phase voltage may be a sine wave, and the phase voltage fed back to the voltage control circuit may be a sine wave.Therefore, the sine wave phase voltage obtained by conversion from the line voltage is fed back. Even in the uninterruptible power supply device that can control the instantaneous voltage and cannot directly detect the phase voltage, the modulation method in which the triple harmonic is superimposed can be applied to increase the utilization rate of the DC voltage.

Further, instead of superimposing the negative envelope signal on the modulation wave, the same effect can be obtained by superimposing the triple harmonic of the phase voltage command value of the sine wave on the modulation wave.

Further, the polarity inversion signal of the negative side envelope signal is multiplied by a coefficient of "1" or less to match the crossing point of the modulated wave with the peak of the trough of the carrier wave, and thus the peak of the trough of the carrier wave.
It is possible to prevent the peak value from matching the zero line of the modulated wave, prevent an increase in switching loss, and eliminate distortion in the output voltage waveform caused by offsetting the carrier wave.

Further, according to the configuration in which the capacitor series connection circuit for dividing the voltage of the DC portion of the inverter is provided to directly detect the phase voltage, the phase voltage command value obtained by distorting the phase voltage target waveform into a trapezoidal wave shape. Even if the phase voltage command value is obtained by superimposing the third harmonic, the detected value of the phase voltage can be fed back and directly matched, and the negative side envelope signal generation circuit as described above. It is possible to improve the voltage utilization rate of the uninterruptible power supply without using the above.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an embodiment of an uninterruptible power supply device of the present invention.

FIG. 2 is a detailed view of a main part of the embodiment shown in FIG.

FIG. 3 is a signal waveform diagram of each part for explaining the operation of the embodiment in FIG.

FIG. 4 is a detailed configuration diagram of a main part corresponding to FIG. 2 of another embodiment.

FIG. 5 is a signal waveform diagram of each part for explaining the operation of the embodiment in FIG. 4;

FIG. 6 is an overall configuration diagram of another embodiment of the uninterruptible power supply device of the present invention.

FIG. 7 is a detailed view of a main part of the embodiment shown in FIG.

FIG. 8 is an overall configuration diagram of another embodiment of the uninterruptible power supply system of the present invention.

FIG. 9 is a detailed view of a main part of the embodiment of FIG.

FIG. 10 is a main part configuration diagram of another embodiment of the present invention.

11 is a detailed diagram of an embodiment of the control circuit of FIG. 10 embodiment; FIG.

12 is a detailed view of another embodiment of the control circuit of FIG. 10 embodiment.

[Explanation of symbols]

 1 DC power supply 2 Inverter 3 Filter 4 Transformer 5 Load 6 Voltage transformer 7 Conversion circuit 8 Voltage control circuit 9, 20 Phase voltage command value generation circuit 11 Modulation circuit 14 Switching control circuit 15, 16 Negative side envelope signal Creation circuit 17 Harmonic signal generation circuit 18, 19 Capacitor 82 Control arithmetic circuit 84 Filter 111 Carrier wave signal generation circuit 112 Comparison circuit 114 Multiplier circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kiichi Tokunaga 4026 Kuji Town, Hitachi City, Ibaraki Prefecture Hitachi Research Laboratory, Hiritsu Manufacturing Co., Ltd.

Claims (5)

[Claims] 1. A line voltage of an output voltage of an inverter having a three-phase bridge-connected switching element for converting DC power into AC is detected, and a phase voltage of each phase is detected from the line voltage. A predetermined carrier wave is modulated by using a phase voltage control signal corresponding to the deviation between the detected phase voltage value and the phase voltage command value of the sine wave as a modulating wave to generate a PWM pulse, and the switching element of the inverter is switched according to the PWM pulse. In an inverter control method for an uninterruptible power supply configured to perform on-off control, a signal corresponding to a negative side envelope relating to a waveform for three phases of either the phase voltage command value of the sine wave or the phase voltage control signal. Is superposed on the modulated wave, an inverter control method for an uninterruptible power supply. 2. An inverter having a three-phase bridge-connected switching element for converting DC power into AC, a voltage transformer connected to the output of the inverter, and a line voltage detected by the voltage transformer. To a phase voltage, and a deviation between the phase voltage detection value output from the conversion circuit and the sine wave phase voltage command value is obtained, and a phase voltage control signal having a value according to the deviation is generated. A voltage control circuit for outputting and a PW for modulating a predetermined carrier wave by using the phase voltage control signal as a modulation wave
An uninterruptible power supply comprising: a modulation circuit that outputs M pulses; and a switching control circuit that controls ON / OFF of a switching element of the inverter according to a PWM pulse that is output from the modulation circuit. A negative-side envelope signal generating circuit that generates a signal corresponding to a negative-side envelope relating to the waveform of one of the three phases of the voltage command value and the phase voltage control signal is provided, and the modulation circuit includes the negative-side envelope. An uninterruptible power supply device comprising an adder circuit for superimposing a signal corresponding to a line on the modulated wave. 3. An inverter having a three-phase bridge-connected switching element for converting DC power into AC, a voltage transformer connected to the output of the inverter, and a line voltage detected by the voltage transformer. To a phase voltage, and a deviation between the phase voltage detection value output from the conversion circuit and the sine wave phase voltage command value is obtained, and a phase voltage control signal having a value according to the deviation is generated. A voltage control circuit for outputting and a PW for modulating a predetermined carrier wave by using the phase voltage control signal as a modulation wave
An uninterruptible power supply comprising: a modulation circuit that outputs M pulses; and a switching control circuit that controls ON / OFF of a switching element of the inverter according to a PWM pulse that is output from the modulation circuit. A harmonic signal generating circuit that generates a triple harmonic of the voltage command value is provided, and the modulating circuit is provided with an adding circuit that superimposes the triple harmonic signal generated by the harmonic signal generating circuit on the modulated wave. An uninterruptible power supply characterized by that. 4. The uninterruptible power supply device according to claim 2, wherein the modulation circuit is provided with a gain multiplication circuit that multiplies the modulated wave by a coefficient of 1 or less. 5. An inverter having a three-phase bridge-connected switching element for converting DC power into AC, a capacitor series connection circuit for dividing a DC voltage of the inverter, and a trapezoidal phase voltage target waveform of the inverter. A phase voltage command value generating circuit that generates a phase voltage command value that is obtained by superimposing a triple harmonic on a phase voltage command value that is distorted in a wave shape or a phase voltage target waveform, and a neutral point of the capacitor series connection circuit. The deviation between the phase voltage detection value obtained by detecting the voltage between each phase of the inverter and the phase voltage command value is obtained, and the phase voltage control signal having a value according to the deviation is generated and output. Voltage control circuit, a modulation circuit that modulates a predetermined carrier wave using the phase voltage control signal as a modulation wave and outputs a PWM pulse, and switching of the inverter according to the PWM pulse output from the modulation circuit. An uninterruptible power supply comprising a switching control circuit for on / off controlling elements.