JP2508900B2 - Control method for multiple inverter device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a triangular wave carrier signal in an active filter or the like for injecting a compensation voltage of a predetermined frequency into a noise generation source to prevent noise components from flowing out to a power system. In order to reduce the size of the filter for removing the frequency component of the multiplex type, a multiplex type for controlling a multiplex type inverter device configured by using a plurality of voltage type pulse width modulation inverters (hereinafter simply referred to as inverters) for generating a compensation voltage The present invention relates to a control method for an inverter device.

[Conventional technology]

FIG. 4 (a) shows a basic circuit diagram of a triplex multiplex inverter device for generating a three-phase AC voltage of U-phase, V-phase and W-phase. In FIG. 4 (a), 1 is a first three-phase inverter, which is composed of a DC power supply 1E and three single-phase inverters 1U, 1V, 1W for U-phase, V-phase and W-phase. . For example, the single-phase inverter 1U consists of four switch elements S _{1 to} S ₄ and diodes D _{1 to} D ₄ connected in antiparallel to the switch elements S _{1 to} S ₄ , respectively, and connecting them in a bridge shape. , Switch element
DC power supply for the connection point of S ₁ and S _{3 and} the connection point of switch elements S ₂ and S _4.
Connected to the positive and negative electrodes of 1E, and switch elements
Output terminals T ₁ and T ₂ are provided at the connection points of S ₁ and S _{2 and} the connection points of switch elements S ₃ and S ₄ , respectively. The remaining single-phase inverters 1V and 1W have the same circuit configuration as the single-phase inverter 1U, though the detailed circuit configuration is omitted in the figure, and the switching elements S ₁ of the single-phase inverters 1U, 1V, and 1W of each phase are used. A pulse width modulation signal, which is the result of comparison between the reference voltage of each phase and the triangular wave carrier voltage, is applied to each of the control poles (not shown) of ~ S ₄ and the single-phase inverters 1U, 1V, 1W A three-phase AC voltage similar to the reference voltage of each phase is output between the output terminals T ₁ and T ₂ . However, since the three-phase AC voltage contains the frequency components of the triangular wave carrier voltage and the harmonic components thereof, it is necessary to remove those frequency components by the LC filter in the subsequent stage.

Reference numeral 2 is a second three-phase inverter, and reference numeral 3 is a third three-phase inverter, and their specific circuit configurations are the same as those of the first three-phase inverter 1. However, the triangular wave carrier signal for creating the pulse width modulation signal applied to each switch element of each single-phase inverter 2 and 3 is 60 degrees and 120 degrees respectively with respect to the triangular wave carrier signal of the first three-phase inverter 1. They differ in that they have a phase delay.

Then, the U phase of the first, second, and third three-phase inverters 1, 2, 3
The V-phase and W-phase voltages are combined. For example, for the U phase, the multiple transformer 4U as shown in FIG. 4 (b) is used, and the output terminals T ₁ and T ₂ of the single phase inverter 1U for the U phase of the first three-phase inverter 1 are multiplexed. Similarly, the output terminals T ₃ and T ₄ of the U-phase single-phase inverter (not shown) of the second three-phase inverter 2 are connected to the primary winding n ₁₁ of the transformer 4U and the primary terminal of the multiple transformer 4U. Connect to the winding n ₁₂ and connect the output terminals T ₅ and T ₆ of the U-phase single-phase inverter (not shown) of the third three-phase inverter 3 to the primary winding n ₁₃ of the multiple transformer 4U. . As a result, the secondary winding n ₂ of the multiple transformer 4U is connected to the first, second, and third three-phase inverters.
The AC voltage of the U-phase obtained by combining the outputs of the single-phase inverters 1U, ... The V phase and the W phase are the same as the U phase.

FIG. 5 is a time chart showing the pattern of the U-phase pulse width modulation signal, the output of each single-phase inverter, and the pattern of the multiple composite output. Hereinafter, with reference to FIG. The operation will be described for the U phase. The same operation is performed for the V phase and the W phase.

In this multiple inverter device, the first three-phase inverter 1 has a reference voltage V _R and a triangular wave carrier indicated by a solid line, as shown in FIG. The signal V ₁₁ and its inverted signal, the triangular carrier signal V ₂₁ indicated by the chain double-dashed line, are compared.

As a result of comparison between the reference voltage V _R and the triangular wave carrier signal V ₁₁ , a rectangular wave (pulse width modulation wave) as shown in FIG. 5 (b) is obtained, and the rectangular wave of FIG. 5 (b) is high. The switch element S ₁ of the single-phase inverter 1U is driven on when it is at the level, and conversely, the switch element S ₂ of the single-phase inverter 1U is driven on when it is at the low level. Further, as a result of comparison between the reference voltage V _R and the triangular wave carrier signal V ₂₁ , a rectangular wave (pulse width modulation wave) as shown in FIG. 5 (c) is obtained, and the rectangular wave of FIG. 5 (c) is obtained. Is high level, the switching element S ₄ of the single-phase inverter 1U is driven on, and conversely, when it is low level, the switching element of the single-phase inverter 1U
S ₃ is turned on the drive. As a result, the output voltage of the single-phase inverter 1U has a waveform as shown in FIG. 5 (d).

Similarly, for the second three-phase inverter 2, as shown in FIG. 5A, the reference voltage V _R , the triangular wave carrier signal V ₁₂ indicated by the short broken line, and the one-dot chain line which is the inverted signal thereof are shown. The triangular carrier signal V ₂₂ is compared. As a result of comparison between the reference voltage V _R and the triangular wave carrier signal V ₁₂ ,
A rectangular wave as shown in FIG. 5 (e) is obtained, and as a result of comparison between the reference voltage V _R and the triangular wave carrier signal V ₂₂ , a rectangular wave as shown in FIG. 5 (f) is obtained. Then, four switching elements similar to the above are driven by these rectangular waves, and the output voltage of the U-phase single-phase inverter is the fifth level.
The waveform is as shown in FIG.

As for the third three-phase inverter 3, as shown in FIG. 5A, the reference voltage V _R , the triangular wave carrier signal V ₁₃ shown by a long broken line, and the three-dot chain line which is the inverted signal thereof are shown. The triangular wave carrier signal V ₂₃ is compared. As a result of comparison between the reference voltage V _R and the triangular wave carrier signal V ₁₃ ,
A rectangular wave as shown in FIG. 5 (h) is obtained, and as a result of comparison between the reference voltage V _R and the triangular wave carrier signal V ₂₃ , a rectangular wave as shown in FIG. 5 (i) is obtained. Then, four switching elements similar to the above are driven by these rectangular waves, and the output voltage of the U-phase single-phase inverter is the fifth level.
The waveform is as shown in FIG.

When the output voltage of each single-phase inverter 1U for U-phase of the three-phase inverters 1, 2 and 3 is multiplexed by the multiple transformer 4U, the voltage of the waveform as shown in Fig. 5 (k) is obtained. To be

With this configuration, the harmonic components of the triangular wave carrier signal included in the output voltage of the multiple transformer 4U include only the sixth and higher harmonic components, and the LC component for removing the harmonic components of the triangular wave carrier signal is included. The resonance frequency of the filter can be set high, and therefore the inductor and the capacitor forming the LC filter can be made small, and the LC filter can be made compact.

[Problems to be Solved by the Invention]

However, when the operation of any one of the three-phase inverters 1, 2 and 3 is stopped, for example, when the operation of the three-phase inverter 3 is stopped, this multi-inverter device has a normal triangular wave of the three-phase inverters 1 and 2 at this time. Since the carrier voltage has a phase difference of 60 degrees as before the failure, the output voltage of the multiple inverter 4U has a waveform as shown in FIG. 5 (l). If the waveform becomes non-uniform on such a time axis, the lowest order of the harmonic components of the triangular wave carrier signal included in the output voltage of the multiple transformer 4U will decrease. That is, in this example, when the frequency of the triangular wave carrier signal is f _c , unnecessary harmonic components due to the triangular wave carrier signal in the range of 2f _c <f <4f _c are generated.

In this way, if the lowest order of unnecessary harmonic components to be removed decreases, it is necessary to set the resonance frequency of the LC filter to remove it to a low value, and therefore set the inductance value of the inductor or the capacitance of the capacitor to a large value. Therefore, there is a problem that the LC filter becomes large.

Therefore, an object of the present invention is to suppress the lowering of the lowest order of the harmonic component of the triangular wave carrier signal in the multiplex combined output voltage when the number of multiplexing is decreased by stopping the operation of the inverter,
It is an object of the present invention to provide a control method for a multiple inverter device that can reduce the size of a filter for removing higher harmonic components of a triangular wave carrier signal.

[Means for solving the problem]

The control method of the multiple inverter device of the present invention is such that when n (n is an integer of 3 or more) inverters are normal, a triangular wave having a phase difference of 180 / n degrees with respect to all n inverters. The carrier signals are respectively supplied, and n
The output of each inverter is combined by the multiple transformer and output. On the other hand, for any reason, one of the n inverters 1
When a stand fails, the operation of the failed inverter is stopped, and the phase difference of the triangular wave carrier signals supplied to the remaining n-1 inverters is switched from 180 / n degrees to 180 / (n-1) degrees. -The output of one inverter is combined by the multiple transformer and output.

[Action]

According to the configuration of the present invention, not only when all the n inverters are normal, but also when any one of the n inverters fails and operation of the inverter is stopped, The phase difference of the triangular wave carrier signal applied to the inverter becomes uniform, and the lowest order harmonic component of the triangular wave carrier signal in the output voltage of the multiple transformer is 2 (n-1).
Therefore, it is possible to prevent generation of harmonic components of orders lower than that. As a result, the resonance frequency of the filter for removing the harmonic component of the triangular wave carrier signal can be set high, and the filter can be downsized.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a multiple inverter device for carrying out a control method according to an embodiment of the present invention. This multiple inverter device is a triple multiplex device that multiplexes the output voltages of the three inverters in a normal state, and is switched to a double multiplex when one inverter fails. This multi-inverter device outputs a three-phase AC voltage, but the U-phase, V-phase, and W-phase have the same configuration, so in FIG. 1 for simplification of the drawing. , The U-phase circuit configuration is shown, and the V-phase and the W-phase are not shown.

In FIG. 1, 1 is a first three-phase inverter, 2 is a second three-phase inverter, 3 is a third three-phase inverter, 1U is a single-phase inverter for U phase in the three-phase inverter 1, and 4U is U
It is a multiple transformer for phase.

Reference numeral 5 is a triangular wave carrier signal generation circuit common to all phases. The triangular wave carrier signals V ₁₁ , V ₁₂ , V ₁₃ having a phase difference of 60 degrees and the triangular wave carrier signal V _{11 having} a phase difference of 90 degrees with respect to each other. While generating the carrier signal V ₁₄ , the triangular wave carrier signals V ₂₁ , V ₂₂ , V ₂₃ , and
Generates V ₂₄ .

6U is a triangular wave carrier signal switching circuit, which is a triangular wave carrier signal V ₁₁ , V generated from the triangular wave carrier signal generating circuit 5.
₁₂ , V ₁₃ , V ₁₄ , V ₂₁ , V ₂₂ , V ₂₃ , V ₂₄ 3 phase inverter 1,2,3
Failure signal K for each single-phase inverter 1U, ...
Based on S _1U , KS _2U , KS _3U , when all three-phase inverters 1, 2, 3 are normal, the triangular wave carrier signals V ₁₁ , V ₁₂ ,, V ₁₃ ,
V ₂₁ , V ₂₂ and V ₂₃ are output corresponding to the three-phase inverters 1, 2 and 3, and when any one of the three-phase inverters 1, 2 and 3 fails, for example, the three-phase inverter 3 At the time of failure, triangular wave carrier signals V ₁₁ , V ₁₄ , V ₂₁ and V ₂₄ are output corresponding to the three-phase inverters 1 and 2. The specific circuit configuration will be described later (see FIGS. 2 (a) and 2 (b)).

7U is a pulse generator circuit, triangular wave carrier signal switching circuit
Reference voltage and triangular wave carrier signal V ₁₁ , V given from 6U
₁₂ , V ₁₃ , V ₁₄ , V ₂₁ , V ₂₂ , V ₂₃ , V ₂₄ are compared with each other, and each single-phase inverter 1U of each three-phase inverter 1, 2, 3 is switched element S ₁ ...
A rectangular wave signal (pulse width modulation signal) for driving S ₄ is created, this rectangular wave signal is amplified, and each three-phase inverter 1,
It is given as a gate pulse to the single-phase inverters 1U, ...

Here, a specific circuit configuration of the triangular wave carrier signal switching circuit 6U will be described with reference to FIGS. 2 (a) and 2 (b). This triangular wave carrier signal switching circuit 6U includes AND gates AN ₁ and AN ₂ and knot circuits NT _{1 to} NT ₄ shown in FIG.
It is composed of switches SW _{1 to} SW ₅ shown in FIG.

When all three three-phase inverters 1, 2, 3 are normal, all three-phase inverters 1, 2, 3 are operated. At this time, as shown in Table 1, failure signals KS _1U , KS _2U , KS _3U are all low, and the control signals SS _{1 to} SS ₅ of the switches SW _{1 to} SW ₅ are low, high, low, high and low, respectively.

As a result, the triangular wave carrier signals V ₁₁ and V ₂₁ are used to control the U-phase single-phase inverter 1U of the 3-phase inverter 1.
The triangular wave carrier signals V ₁₂ and V ₂₂ are used to control the U-phase single-phase inverter of the three-phase inverter 2, and the triangular wave carrier signals V ₁₃ and V ₂₃ are used to control the U-phase single-phase inverter of the three-phase inverter 3. Used for control. In other words, three-phase inverter 1,2,
Triangle wave carrier signals V ₁₁ , V ₂₁ ; V ₁₂ , V ₂₂ ; V ₁₃ , V having a phase difference of 60 degrees to each of the three U-phase single-phase inverters 1U, ...
₂₃ will be provided. The time chart of each part of the multiple inverter device at this time is shown in FIGS.
Same as before.

Next, for example, when the three-phase inverter 3 fails,
The operation of the three-phase inverter 3 is stopped, and only the remaining three-phase inverters 1 and 2 are operated. At this time, the failure signal KS _1U ,
KS _2U, the control signal SS ₁ ~ SS ₅ of KS _3U and the switch SW ₁ to SW ₅ 3
The triangular wave carrier signals of the phase inverters 1 to 3 are as shown in Table 2.

That is, the triangular wave carrier signals V ₁₁ , V ₂₁ ; V ₁₄ and V ₂₄ having a phase difference of 90 degrees are provided to the U-phase single-phase inverters 1U, ... Of the three-phase inverters 1 and 2, respectively. In the three-phase inverters 1 and 2, the triangular wave carrier signals V ₁₁ , V ₂₁ , V ₁₄ and V ₂₄ have equal phase differences.

FIG. 3 is a time chart showing the pattern of U-phase pulse width modulation signal generation and the pattern of the output of each single-phase inverter and the multiplex composite output when the number of multiplexes decreases due to the failure of the three-phase inverter 3. The operation of this multiple inverter device when the number of multiplexes is reduced will be described with reference to FIG. The same operation is performed for the V phase and the W phase.

In this multiple inverter system, for the first three-phase inverter 1, as shown in FIG. 3 (a), the reference voltage V _R
And the triangular wave carrier signal V ₁₁ indicated by the solid line and the inverted triangular wave carrier signal V ₂₁ indicated by the chain double-dashed line.

As a result of comparison between the reference voltage V _R and the triangular wave carrier signal V ₁₁ , a rectangular wave (pulse width modulation wave) as shown in FIG. 3B is obtained, and the rectangular wave of FIG. 3B is high. The switch element S ₁ of the single-phase inverter 1U is driven on when it is at the level, and conversely, the switch element S ₂ of the single-phase inverter 1U is driven on when it is at the low level. As a result of comparison between the reference voltage V _R and the triangular wave carrier signal V ₂₁ , a rectangular wave (pulse width modulation wave) as shown in FIG. 3 (c) is obtained. The rectangular wave of FIG. 3 (c) is obtained. Is high level, the switching element S ₄ of the single-phase inverter 1U is driven on, and conversely, when it is low level, the switching element of the single-phase inverter 1U
S ₃ is turned on the drive. As a result, the output voltage of the single-phase inverter 1U has a waveform as shown in FIG. 3 (d). The operation of this single-phase inverter 1U is similar to that of the conventional example.

Next, as for the second three-phase inverter 2, as shown in FIG. 3 (a), the reference voltage V _R , the triangular wave carrier signal V ₁₄ shown by the short broken line, and the one-dot chain line which is the inverted signal thereof are shown. The triangular carrier signal V ₂₄ is compared.

As a result of comparison between the reference voltage V _R and the triangular wave carrier signal V ₁₄ , a rectangular wave (pulse width modulation wave) as shown in FIG. 3 (e) is obtained, and the rectangular wave in FIG. 3 (e) is high. The switch element S ₁ of the U-phase single-phase inverter is turned on when the level is on the contrary, and the switch element S ₂ of the U-phase single-phase inverter is on-driven when the level is low. Further, as a result of comparison between the reference voltage V _R and the triangular wave carrier signal V ₂₄ , a rectangular wave (pulse width modulation wave) as shown in FIG. 3 (f) is obtained, and the rectangular wave of FIG. 3 (f) is obtained. Is high level, the switch element S ₄ of the U-phase single-phase inverter is driven on, and conversely, when it is low level, the switch element S ₃ of the U-phase single-phase inverter is on-driven. As a result, the output voltage of the U-phase single-phase inverter is shown in Fig. 3 (g).
The waveform is as shown in FIG.

Then, when the output voltages of the U-phase single-phase inverters 1U, ... Of the three-phase inverters 1 and 2 are multiplexed by the multiple transformer 4U, a voltage having a waveform as shown in FIG. 3 (h) is obtained, The harmonic components of the triangular wave carrier signal included in this waveform are fourth or higher, and third or lower harmonic components are not included.
This is because the triangular wave carrier signals V ₁₁ , V ₂₁ , V ₁₄ and V ₂₄ applied to the three-phase inverters 1 and 2 have the same phase difference.

Next, for example, when the three-phase inverter 2 fails,
The operation of the three-phase inverter 2 is stopped, and only the remaining three-phase inverters 1 and 3 are operated. At this time, the failure signal KS _1U ,
KS _2U, the control signal SS ₁ ~ SS ₅ of KS _3U and the switch SW ₁ to SW ₅ 3
The triangular wave carrier signals of the phase inverters 1 to 3 are as shown in Table 3.

That is, the triangular wave carrier signals V ₁₁ , V ₂₁ ; V ₁₄ , V ₂₄ having a phase difference of 90 degrees are provided to the U-phase single-phase inverters 1U, ... Of the three-phase inverters 1, 3, respectively. .

Next, for example, when the three-phase inverter 1 fails,
The operation of the three-phase inverter 1 is stopped, and only the remaining three-phase inverters 2 and 3 are operated. At this time, the failure signal KS _1U ,
KS _2U, the control signal SS ₁ ~ SS ₅ of KS _3U and the switch SW ₁ to SW ₅ 3
The triangular wave carrier signals of the phase inverters 1 to 3 are as shown in Table 4.

That is, the triangular wave carrier signals V ₁₁ , V ₂₁ ; V ₁₄ , V ₂₄ having a phase difference of 90 degrees are supplied to the U-phase single-phase inverters 1U, ... Of the three-phase inverters 2, 3, respectively. .

With this configuration, the harmonic components of the triangular wave carrier signal included in the output voltage of the multiple transformer 4U include only the fourth and higher harmonic components, and the three-phase inverters 1, 2,
Although all 3 are lower than the lowest 6th order under normal conditions, they can be higher than the lowest 2nd order under failure of the three-phase inverter 3 in the conventional example. Therefore, to remove the harmonic components of the triangular wave carrier signal,
The resonance frequency of the LC filter can be set high, and therefore the inductor and the capacitor forming the LC filter can be made small, and the LC filter can be made compact.

It should be noted that, in the above-described embodiment, the case where the phase difference of the triangular wave carrier signal is switched from 60 degrees to 90 degrees when the number of multiplexing in the normal state is 3 and the number of multiplexing is reduced to 2 in the case of failure has been described. Without being limited to this, the number of multiplexing in a normal state is n
The present invention can be applied to the case where the number of multiplexes is reduced to n-1 at the time of failure with the above integers. In this case, the phase difference of the triangular wave carrier signal is 180 / n degrees to 180 / n degrees.
It will be switched every (n-1) degrees.

In the above-mentioned embodiment, the embodiment of the multiple inverter device for generating a three-phase AC voltage has been described, but it goes without saying that the present invention can be applied to a device for generating a single-phase AC voltage.

〔The invention's effect〕

According to the control method of the multiple inverter device of the present invention,
Not only when all the n inverters are normal, but also when any one of the n inverters fails and the operation of the inverter is stopped, the position of the triangular wave carrier signal to be added to the operating inverters. The phase difference can be made uniform, the lowest order of the harmonic components of the triangular wave carrier signal in the output voltage of the multi-transformer can be made higher than that at the time of failure of the conventional example, and the harmonic components of the triangular wave carrier signal can be removed. Therefore, the resonance frequency of the filter can be set high, and the filter can be downsized.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a multiple inverter device according to an embodiment of the present invention, FIG. 2 is a circuit diagram showing the specific configuration of the essential parts of FIG. 1, and FIG. FIG. 4 is a time chart showing the operation of the multiple inverter device, FIG. 4 is a circuit diagram showing the configuration of a conventional example of the multiple inverter device, and FIG. 5 is a time chart showing the operation of the multiple inverter device of FIG. 1-3 …… three-phase inverter, 4U …… multiple transformer, 5 ……
Triangle wave carrier signal generation circuit, 6U …… Triangle wave carrier signal switching circuit, 7U …… Pulse generation circuit

Claims (1)

(57) [Claims] 1. A triangular wave carrier signal having a phase difference of 180 / n degrees is supplied to each of n voltage type pulse width modulation inverters (n is an integer of 3 or more), and the n voltage types are supplied. A method of controlling a multi-inverter device for combining outputs of a pulse width modulation inverter with a multi-transformer and outputting the combined voltage, wherein when any one of the n voltage type pulse width modulation inverters fails, the failed voltage type pulse width modulation The inverter operation is stopped and the phase difference of the triangular wave carrier signals supplied to the remaining n-1 voltage type pulse width modulation inverters is 180 /
A method of controlling a multi-inverter device, characterized by switching from n degrees to 180 / (n-1) degrees.