JP5652593B2 - Power converter - Google Patents

Description

  The present invention relates to a power conversion device that drives a two-phase motor, for example, at a variable speed.

FIG. 11 is a configuration diagram of a variable speed drive system for a two-phase motor based on the contents of Non-Patent Document 1 described later. FIG. 12 is a phasor diagram showing the amplitude and phase relationship of the voltage command and the like of the power converter in this variable speed drive system.
Hereinafter, each output voltage (M phase voltage v _M , A phase voltage v _A , C phase voltage v _C ) of the terminals M, A, and C viewed from the DC midpoint N in FIG. Are referred to as line voltages ( _MC line voltage v _MC , _AC line voltage v _AC , _MA line voltage v _MA ).

The power conversion device 100 shown in FIG. 11 is configured by connecting an IGBT and a free wheel diode in antiparallel to each other to form a semiconductor switch (hereinafter, the semiconductor switch is abbreviated as IGBT as needed) T _MP , T _MN , T _AP , T _AN. , T _CP , T _CN and the first semiconductor switch series circuit formed by connecting the first semiconductor switch T _MP and the second semiconductor switch T _MN in series, and the third semiconductor switch T _AP , A second semiconductor switch series circuit in which a fourth semiconductor switch _TAN is connected in series, and a third semiconductor switch in which a fifth semiconductor switch _TCP and a sixth semiconductor switch _TCN are connected in series An inverter unit is configured by connecting a series circuit in parallel, and this inverter unit is connected in parallel to the DC power source 103 and the series circuit of the smoothing capacitors 101 and 102. It is constituted by connection. Here, the DC power source 103 and the series circuit of the smoothing capacitors 101 and 102 are collectively referred to as a DC voltage source.
The load of the power conversion device 100 is a two-phase motor (induction motor) 200 having two windings 201 and 202, and three input terminals thereof are a first semiconductor switch _TMP and a second semiconductor switch. A series connection point with _TMN , a series connection point with the third semiconductor switch _TAP and the fourth semiconductor switch _TAN, and a series connection point with the fifth semiconductor switch _TCP and the sixth semiconductor switch _TCN. Each is connected.

The two windings 201 and 202 of the electric motor 200 are spatially displaced by 90 degrees. Therefore, the power converter 100 applies the electric phase angle of the _MC line voltage v _MC and the _AC line voltage v _AC in FIG. The electric motor 200 is driven at a variable speed by adjusting the amplitude and frequency.

Here, in order to obtain desired output line voltages v _MC and v _AC in the power conversion device 100, it is necessary to turn on and off the IGBTs constituting the power conversion device 100 according to a predetermined switching pattern. Therefore, in Non-Patent Document 1, each IGBT is switched by the gate signal obtained by comparing the three phase voltage commands v _M ^* , v _A ^* , v _C ^* and the carrier triangular wave, and thereby the target output line Inter-voltages v _MC and v _AC are obtained.

For example, when the amplitudes of desired output line voltages v _MC and v _AC are equal and the electrical phase angles are different by 90 degrees, the three phase voltage commands v _M ^* , v _A ^* and v _C ^* and the output line voltage The amplitude and phase relationships of v _MC and v _AC are as shown in FIG. 12. If the amplitude of the output line voltage is V, the output line voltage v _MC , v _AC (output line voltage command v _MC ^* , v _The same applies to _AC ^* ) and the phase voltage commands v _M ^* , v _A ^* , and v _C ^* are expressed as Equations 1 to 5.

FIG. 13A is a waveform diagram showing a modulation signal and a carrier triangular wave for each phase of the power conversion apparatus 100, and FIG. 13B is a waveform diagram showing an output voltage (line voltage and phase voltage). .
Λ _M ^* , λ _A ^* , and λ _C ^{* in} FIG. 13A are obtained by using the phase voltage commands v _M ^* , v _A ^* , and v _C ^* , respectively, using the DC voltage detection value E _dc of the DC voltage source. This is a phase voltage command whose amplitude is corrected (hereinafter, a voltage command whose amplitude is corrected using the detected DC voltage value E _dc is also referred to as a modulation signal), but since the correction method is not the gist of the present invention, it will be described here. Is omitted.
By comparing the modulation signals λ _M ^* , λ _A ^* , and λ _C ^* obtained by the amplitude correction with the carrier triangular wave in the figure, the gate signal of the IGBT constituting the power converter 100 is generated, and according to this gate signal By turning on and off the IGBT, output line voltages v _MC and v _AC as shown in FIG. 13B can be obtained.

"A New Modulation Strategy for Unbalanced Two Phase Induction Motor Drives Using a Three-Leg Voltage Source Inverter", IEEJ Transactions D, vol.125, No.5, p482-491, 2005

As can be seen from FIGS. 13A and 13B, conventionally, the modulation signals λ _M ^* , λ _A ^* , and λ _C ^{* to} be compared with the carrier triangular wave are sine waves. Therefore, the IGBT always repeats on and off. Therefore, a switching loss occurs with the switching of the IGBT. This switching loss causes an increase in the amount of heat generated by the IGBT, resulting in an increase in the size of cooling fins and the like for cooling the IGBT, which hinders reduction in size, weight, and cost of the entire apparatus.
SUMMARY OF THE INVENTION An object of the present invention is to provide a power conversion device that can reduce switching loss in a semiconductor switch and can reduce the size, weight, and cost of the entire device by downsizing the cooling device.

In order to solve the above-mentioned problem, the invention according to claim 1 includes a first semiconductor switch series circuit configured by connecting a first semiconductor switch and a second semiconductor switch in series,
A second semiconductor switch series circuit configured by connecting a third semiconductor switch and a fourth semiconductor switch in series;
A third semiconductor switch series circuit configured by connecting a fifth semiconductor switch and a sixth semiconductor switch in series;
Connect all the DC voltage sources in parallel,
Series connection point of the first semiconductor switch and the second semiconductor switch, Series connection point of the third semiconductor switch and the fourth semiconductor switch, Series connection point of the fifth semiconductor switch and the sixth semiconductor switch Are connected to a load as output terminals of the first phase, the second phase, and the third phase, respectively,
Voltage detecting means for detecting a DC voltage of the DC voltage source;
Among the first to third voltage commands for the first phase to the third phase, voltage command generating means for generating two voltage commands having the same amplitude and the electrical phase angle shifted by 180 degrees;
First voltage command correcting means for correcting the amplitude of the first to third voltage commands according to the voltage detection value by the voltage detecting means;
Among the first to third semiconductor switch series circuits, the semiconductor switch constituting one semiconductor switch series circuit is repeatedly turned on and off, and at least one of the four semiconductor switches constituting the remaining two semiconductor switch series circuits. And a second voltage command correcting unit that corrects the first to third voltage commands whose amplitudes are corrected by the first voltage command correcting unit so that the switch is kept in an ON state.

The invention according to claim 2 is the power conversion device according to claim 1,
The second voltage command correction means is configured to output a voltage command of a phase having a semiconductor switch for holding an ON state among the first to third voltage commands whose amplitude is corrected by the first voltage command correction means. A correction signal that is equal to the maximum value or the minimum value of the carrier triangular wave for generating the on / off signal of the semiconductor switch constituting the switch series circuit is calculated, and the amplitude of the correction signal is corrected by the first voltage command correction means. it is intended to have a first through third means for adding each to all voltage command that is.

  ADVANTAGE OF THE INVENTION According to this invention, the frequency | count of switching of the semiconductor switch which comprises a power converter device can be decreased by correct | amending the modulation signal of each phase using the correction signal produced | generated based on the voltage command. As a result, switching loss in the power conversion device can be reduced, and downsizing and cooling of the entire device can be achieved by downsizing the cooling device.

It is a control block diagram in a 1st embodiment of the present invention. It is a flowchart which shows operation | movement of the correction signal calculating means in the basic form of this invention. It is a figure which shows the example of a waveform of each part in the basic form of this invention. It is a figure which shows the example of a waveform of each part in the basic form of this invention. It is a flowchart which shows operation | movement of the correction signal calculating means in 1st Embodiment of this invention. It is a figure which shows the example of a waveform of each part in 1st Embodiment of this invention. It is a control block diagram in a reference form of the present invention. It is a flowchart which shows operation | movement of the correction signal calculating means in the reference form of this invention. It is a figure which shows the example of a waveform of each part in the reference form of this invention. It is a phasor figure which shows the amplitude and phase relationship, such as a voltage command, in the reference form of this invention. 1 is a configuration diagram of an induction motor variable speed drive system based on the content of Non-Patent Document 1. FIG. It is a phasor figure which shows amplitude and phase relationship, such as a voltage command of the power converter device in FIG. It is a wave form diagram which shows the modulation signal, carrier triangular wave, and output voltage in FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In addition, the structure of the main circuit of the power converter device which concerns on this embodiment is the same as that of the power converter device 100 shown in FIG. 11, The load is also the two-phase electric motor 200 which has the two windings 201 and 202 And For this reason, the following description presupposes the power converter device 100 shown in FIG.

First, FIG. 3 shows a waveform example of each part in the basic form of the present invention. FIG. 3A shows the phase voltage commands v _M ^* , v _A ^* , v _C ^* of the power converter 100. The corresponding modulation signals λ _M ^* , λ _A ^* , λ _C ^* and their correction signals λ ₀ ^* are shown. FIG. 3B shows a modulation signal (phase voltage command) λ _M ^** , λ _A ^** , λ _{C obtained} by adding the correction signal λ ₀ ^* to the modulation signals λ _M ^* , λ _A ^* , λ _C ^{*. **} is shown, and FIG. 3C shows each waveform of the output voltage (output phase voltages v _M , v _A , v _C and output line voltages v _MC , v _AC ).
Note that the output voltage waveform is normally a pulse train waveform accompanying switching of the IGBT, but only the fundamental wave component from which the switching component is removed is shown here for ease of explanation.

Now, in this form state, as shown in FIG. 3 (b), the modulation signal lambda _M ^** after correction, λ _A ^**, λ _C ^** is not a sine wave, over a specific period of time, each modulation signal lambda 13 differs from the prior art in FIG. 13 in that _M ^** , λ _A ^** , and λ _C ^** hold the same value as the maximum value or the minimum value of the carrier triangular wave to be compared with them. By using such modulation signals λ _M ^** , λ _A ^** , and λ _C ^** , the phase voltages v _M , v _A , and v _C are not sine waves as shown in FIG. The line voltages v _MC and v _AC applied to the windings 201 and 202 of the electric motor 200 are sine waves.
In this case, the three IGBTs λ _M ^** , λ _A ^** , and λ _C ^** have the same value as the maximum value or the minimum value of the carrier triangular wave, so the IGBT does not perform switching. In the entire converter, the number of switching operations is reduced as compared with the prior art, and the switching loss can be reduced.

Hereinafter, the configuration and operation of the present form state will be described in detail with reference to FIGS. FIG. 1 is a control block diagram in the present form state, FIG. 2 is a flow chart for calculating the correction signal lambda ₀ ^*.

In the form status of this, equal amplitude and M-phase voltage v _M and A-phase voltage v _A, with each phase is inverted (i.e. electrical phase angle is 180 degrees), M-phase voltage v the amplitude of _M and a-phase voltage _{v a} shall be controlled to be 1/2 of the amplitude of the a-M line-to-line voltage _{v MA.}
Now, when the line voltage commands v _MC ^* and v _AC ^* are given, the phase voltage commands v _M ^* , v _A ^* , and v _C ^* can be calculated by Formulas 6 to 8.
These calculations are performed by the phase voltage command calculation means 300 in FIG. The phase voltage command calculation means 300 includes adders 301 and 302, an amplifier 303 _M having a gain (0.5), and amplifiers 303 _A and 303 _C having a gain (−0.5).

Even when the amplitudes of the two line voltage commands v _MC ^* and v _AC ^* are different from each other and the phase difference between the two commands is not 90 degrees as described above, the phase voltage commands v _M ^* , v _A ^* and v _C ^* can be easily calculated.

The phase voltage commands v _M ^* , v _A ^* , and v _C ^* obtained by the phase voltage command calculation unit 300 are input to the first voltage command correction unit 400. The voltage command correcting means 400 divides “2” by the DC voltage detection value E _dc and multiplies the output of the divider 402 by the phase voltage commands v _M ^* , v _A ^* , and v _C ^* , respectively. The multipliers 401 _M , 401 _A , and 401 _C are configured, and the outputs of these multipliers 401 _M , 401 _A , and 401 _C are modulated signals λ _M ^* , λ _A ^* , and λ _C ^* .

The modulation signals λ _M ^* , λ _A ^* , and λ _C ^* are input to the second voltage command correction unit 500. The voltage command correction means 500 includes a correction signal calculation means 501 for calculating a correction signal λ ₀ ^* as shown in FIG. 3A from the modulation signals λ _M ^* , λ _A ^* , λ _C ^*, and the correction signal. Adders 502 _M , 502 _A that add λ ₀ ^* to the modulation signals λ _M ^* , λ _A ^* , λ _C ^* , respectively, to obtain final modulation signals λ _M ^** , λ _A ^** , λ _C ^** , and a 502 _C.
Here, as a result of adding the modulation signals λ _M ^* , λ _A ^* , λ _C ^* and the correction signal λ ₀ ^* , the correction signal calculation unit 501 performs a final process over a specific period as shown in FIG. The correction signal λ ₀ ^* is generated so that one of the modulation signals λ _M ^** , λ _A ^** , and λ _C ^** becomes equal to the maximum value or the minimum value of the carrier triangular wave. Details of the correction signal calculation means 501 will be described later.

Next, the final modulation signals λ _M ^** , λ _A ^** and λ _C ^** output from the second voltage command correction means 500 are converted into carrier triangular waves in the comparators 601 _M , 601 _A and 601 _C , respectively. The outputs are compared with each other as they are or through the inverters 602 _M , 602 _A , and 602 _C , so that the gate signals G _TMP , G _TMN , G _TAP , G _TAN , G _TCP , G _TCN .

With the above operation, the final modulation signals λ _M ^** , λ _A ^** , and λ _C ^** are not sine waves as shown in FIG. 3B, and the phase voltages v _M , v _A , v The waveform of _C is not a sine wave as shown in FIG. However, since the same correction signal λ ₀ ^* is added to the modulation signals λ _M ^* , λ _A ^* , λ _C ^* obtained from the target line voltage commands v _MC ^* , v _AC ^* , the power conversion device In 100 output line voltages (difference voltage between one phase voltage and the other phase voltage), the correction signal λ ₀ ^* component superimposed on each phase voltage is not canceled and does not appear, and the command v _MC ^* , v A sinusoidal line voltage v _MC , v _AC can be obtained as _AC ^* .

Next, the operation of the correction signal calculation unit 501 will be described. FIG. 2 is a flowchart for calculating the correction signal λ ₀ ^* , which is implemented in the correction signal calculation means 501.
(1) First, the absolute values of the M-phase and C-phase modulation signals λ _M ^* , λ _C ^* are calculated to obtain the absolute values λ _M ^* _ABS , λ _C ^* _ABS (step S1). As described above, since the M-phase voltage command v _M ^* and the A-phase voltage command v _A ^* are voltage commands that have the same amplitude and the phase is inverted, the absolute value λ _M ^* _ABS of the M-phase modulation signal is It becomes equal to the absolute value λ _A ^* _{ABS of the} A phase modulation signal.

(2) Next, the magnitude relationship between the absolute value λ _M ^* _{ABS of the M-} phase modulation signal and the absolute value λ _C ^* _ABS of the C-phase modulation signal is determined, and the final modulation signal of which phase is the maximum of the carrier triangular wave It is selected whether it is the same as the value or the minimum value (step S2). Specifically, when the following Expression 9 is satisfied, either one of the M phase modulation signal λ _M ^** or the A phase modulation signal λ _A ^** is set to the same value as the maximum value of the carrier triangular wave, On the other hand, when Expression 9 is not satisfied, the C-phase modulation signal λ _C ^** is set to the same value as the maximum value or the minimum value of the carrier triangular wave.

(3) In step S2, for example, if it is selected that one of the M-phase modulation signal λ _M ^{** and the} A-phase modulation signal λ _A ^** is set to the same value as the maximum value of the carrier triangular wave (step S1) S2 YES), it is selected which of the M-phase modulation signal λ _M ^{** and the} A-phase modulation signal λ _A ^** is set to the same value as the maximum value of the carrier triangular wave (step S3).
Specifically, when the following Expression 10 is satisfied, a correction amount λ ₀ ^* is set so that the M-phase modulation signal λ _M ^** becomes the same value as the maximum value (here, 1) of the carrier triangular wave. Calculation is performed using the following equation 11 (YES in steps S3 and S5). If Expression 10 is not satisfied, a correction amount λ ₀ ^* is calculated by Expression 12 below so that the A-phase modulation signal λ _A ^** becomes the same value as the maximum value of the carrier triangular wave (Steps S3NO, S6). ).

(4) On the other hand, if it is selected in step S2 that C-phase modulation signal λ _C ^** is set to the same value as the maximum or minimum value of the carrier triangular wave (NO in step S2), C-phase modulation signal λ _M ^{** It} is selected whether to set ^* to the same value as the maximum value or the minimum value of the carrier triangular wave (step S4).
Specifically, when the following Expression 13 is satisfied, the correction signal λ ₀ ^* is set so that the C-phase modulation signal λ _C ^** becomes the same value as the maximum value (here, 1) of the carrier triangular wave. Calculation is performed by the following formula 14 (steps S4 YES, S7). If Expression 13 is not satisfied, a correction signal λ ₀ ^* that causes the C-phase modulation signal λ _C ^** to be the same value as the minimum value (here, −1) of the carrier triangular wave is expressed by Expression 15 below. Calculate (steps S4 NO, S8).

In the example described above, the M-phase modulation signal λ _M ^** or the A-phase modulation signal λ _A ^** is set to be the same as the maximum value of the carrier triangular wave, but is set to be the same as the minimum value of the carrier triangular wave. It may be. Furthermore, as shown in FIG. 4B (the above-described FIG. 3 shows a waveform example for one output period, FIG. 4 shows a waveform example for two output periods), the M-phase modulation signal λ _M ^{* * And} A phase modulation signal λ _A ^** may be alternately the same as the maximum value and the minimum value of the carrier triangular wave.

Next, FIG. 6 shows a waveform example of each part in the first embodiment of the present invention.
In the first embodiment as well, the modulated signals λ _M ^** , λ _A ^** , and λ _C ^** after correction are not sine waves, as in the basic embodiment. In the basic mode, any one of the three modulation signals λ _M ^** , λ _A ^** , and λ _C ^** holds the same value as the maximum value or the minimum value of the carrier triangular wave for a specific period. On the other hand, in the present embodiment, one of the two modulation signals λ _M ^** and λ _C ^** holds the same value as the maximum value or the minimum value of the carrier triangular wave for a specific period. The signal λ _A ^** does not hold the same value as the maximum value or the minimum value of the carrier triangular wave.

Hereinafter, in the first embodiment, description of the same parts as the basic form will be omitted, and different parts will be mainly described.
The control block can be represented in FIG. 1 similarly to the basic form, and the function of the correction signal calculation means 501 in FIG. 1 is different from the basic form.
That is, in the correction signal calculation means 501, as a result of adding the modulation signals λ _M ^* , λ _A ^* , λ _C ^* and the correction signal λ ₀ ^* , as shown in FIG. 6B, the final modulation signal λ _M A correction signal λ ₀ ^* is generated so that one of ^** and λ _C ^** is equal to the maximum value or the minimum value of the carrier triangular wave.
Even in this case, a desired output line voltage can be obtained for the same reason as in the basic mode.

Next, the operation of the correction signal calculation unit 501 in this embodiment will be described.
FIG. 5 is a flowchart for calculating the correction signal λ ₀ ^* , which is implemented in the correction signal calculation means 501. Here, for calculating a correction signal λ ₀ ^* such that one of the modulation signals λ _M ^** and λ _C ^** holds the same value as the maximum value or the minimum value of the carrier triangular wave for a specific period. It becomes operation.

(1) First, as in step S1 in FIG. 2, the absolute values of the M-phase modulation signal λ _M ^* and the C-phase modulation signal λ _C ^* are calculated to obtain absolute values λ _M ^* _ABS and λ _C ^* _ABS ( Step S11).
(2) Next, the magnitude relationship between the absolute value λ _M ^* _{ABS of the M-} phase modulation signal and the absolute value λ _C ^* _ABS of the C-phase modulation signal is determined, and the final of which phase of the M phase and the C phase is determined. It is selected whether to make the same modulation signal the same as the maximum value or the minimum value of the carrier triangular wave (step S12). Specifically, if the following Expression 16 is satisfied, the M phase is selected (step S12 YES), and if not satisfied, the C phase is selected (step S12 NO).

(3) In step S12, for example, when the M phase is selected, the sign of the M phase modulation signal λ _M ^* is further determined (YES in steps S12 and S13).
(4) If the M-phase modulation signal λ _M ^* is positive, the correction signal λ is such that the final M-phase modulation signal λ _M ^** is equal to the maximum value of the carrier triangular wave (here, 1). ₀ ^* is calculated by the following equation 17 (YES in steps S13 and S15).

(5) If the M-phase modulation signal λ _M ^* is negative, a correction signal that makes the final M-phase modulation signal λ _M ^** equal to the minimum value (here, −1) of the carrier triangular wave. λ ₀ ^* is calculated by the following mathematical formula 18 (steps S13 NO, S16).

When the phase C is selected in step S12 (NO in step S12), in steps S14, S17, and S18, λ _M ^* and λ _M ^** in the above (4) and (5) are changed to λ _C ^* , This is the same as the processing read as λ _C ^** .

Here, as the two-phase motor 200 that is the load of the power conversion device 100, it is assumed that the mechanical structures and electrical characteristics of the two windings 201 and 202 are different. For example, when the wire diameter of the wire constituting the A-phase winding is thin relative to the wire diameter of the wire constituting the M-phase winding, the impedance is not only different between the two phases, but also of the A-phase winding. Since the wire diameter is thin, it is necessary to reduce the A-phase current with respect to the M-phase current in order to prevent abnormal heat generation in the A-phase winding.
In this case, it is necessary to intentionally reduce the current flowing in the A phase with respect to the M phase by adjusting the magnitude of the output voltage by the power conversion device 100, but the A phase current in that case Various means are conceivable as means for suppressing the above, and the description is omitted because it is not the gist of the present invention.

Note that since the combined current of the M-phase current and the A-phase current flows in the C phase of the two-phase motor 200, the smallest current among the three phases flows in the A phase. This means that the loss generated in the IGBT T _AP and T _AN of the upper and lower arms connected to the A phase in FIG. 11 is small, in other words, the IGBT T of the upper and lower arms connected to the M phase and the C phase. _{MP, T} MN, _T CP, which means that a large loss occurring in _{T CN.}
However, in the present embodiment, the number of switching times of the phase with a small generated loss is originally equal to that of the conventional one, and the switching frequency of the phase with a large generated loss is reduced, thereby effectively reducing the loss generated in the entire power converter. can do.

Next, FIG. 9 shows a waveform example of each part in the reference embodiment of the present invention. 9A shows the modulation signals λ _M ^* , λ _A ^* , λ _C ^* and their correction signals λ ₀ ^* , and FIG. 9B shows the modulation signals λ _M ^* , λ _A ^* , λ _C. ^The final modulation signal λ _M ^** , λ _A ^** , λ _C ^** and carrier triangular wave obtained by adding the correction signal λ ₀ ^* to ^* , and FIG. 9C shows the output voltage (output phase The waveforms of voltages v _M , v _A , v _C and output line voltages v _MC , v _AC ) are shown respectively. Here, only the fundamental wave from which the switching component is removed is shown for the output voltage waveform.

Also in this reference embodiment, the final modulation signals λ _M ^** , λ _A ^** , and λ _C ^** are not sine waves, and the modulation signals λ _M ^** , λ _A ^** , and λ _C ^** are respectively It holds the same value as the maximum or minimum value of the carrier triangular wave for a specific period. By using such modulation signals λ _M ^** , λ _A ^** and λ _C ^** , the phase voltages v _M , v _A and v _C are not sine waves as shown in FIG. 9C. The line voltages v _MC and v _AC are sine waves, and the phase IGBT whose final modulation signal is the same value as the maximum value or the minimum value of the carrier triangular wave does not perform switching, so that switching loss can be reduced. .

Figure 7 shows a control block diagram in the present form state. In FIG. 7, components having the same configurations and functions as those in FIG. 1 are denoted by the same reference numerals, and the following description will be made with reference to the waveforms in FIG.
In this form state, upon variable speed drives a two-phase motor 200, electrically shifted by 120 degrees the phase angle of the three phase voltages, and, of the three phase voltages, the other an amplitude of at least one phase voltage By making the phase voltage different from the amplitude of the desired output line voltage, a desired output line voltage is obtained.

For example, the amplitude commands for two desired line voltages (between M and C and between A and C) are V _MC ^* and V _AC ^* , respectively, and the line voltage command v _AC ^* between A and C is M− In the case where the phase lead is 90 degrees with respect to the inter-C line voltage command v _MC ^* , the amplitude commands V _C ^* , V _A ^* , and V _M ^* of the respective phase voltages are calculated by Formulas 19 to 21, respectively. be able to.

Here, when the amplitude commands V _MC ^* and V _AC ^* of the desired two line voltages are equal, that is, when Expression 22 holds, Expressions 23 to 25 can be obtained.

The calculation described above is realized by the phase voltage command calculation means 350 in FIG.
That is, the desired line voltage amplitude commands V _MC ^* and V _AC ^* calculated by the line voltage amplitude command calculation unit 351 in the phase voltage command calculation means 350 are the M phase voltage amplitude command calculation units 352 _M , A The phase voltage amplitude command calculation unit 352 _A and the C phase voltage amplitude command calculation unit 352 _C are input to the calculation unit 352 _M , 352 _A , 352 _C , and the amplitude command V _M ^* , V _A ^* , V _C ^* is calculated by, for example, the above-described Equations 19 to 21.

On the other hand, when the frequency command F ^* is calculated in the frequency command calculation unit 354, the electrical angle calculation unit 355 calculates the electrical angle θ based on the frequency command F ^* . This electrical angle θ is input to the phase voltage reference sine wave signal calculation unit 356, the amplitude is 1, and the reference sine wave command v _M0 ^{* serving as} a reference for each phase voltage command with each electrical phase angle shifted by 120 degrees ^. , V _A0 ^* , v _C0 ^* are calculated.
Next, the reference sine wave commands v _M0 ^* , v _A0 ^* , v _C0 ^* and the amplitude commands V _M ^* , V _A ^* , V of the respective phase voltages previously calculated by the calculation units 352 _M , 352 _A , 352 _C. Each phase voltage command v _M ^* , v _A ^* , v _C ^* is calculated by multiplying _C ^* by multipliers 353 _M , 353 _A , and 353 _C, respectively.
To summarize the above, each phase voltage command v _M ^* , v _A ^* , v _C ^* can be expressed by Expression 26 to Expression 28. However, Expression 29 to Expression 31 are used as conditions.

Here, as is clear from Equations 19 to 21 and Equations 26 to 28, amplitude commands V _MC ^* and V _AC ^{* of} desired two line voltages (between M and C and between A and C) ^. Are different, and the _AC line voltage command v _AC ^* is 90 degrees ahead of the _MC line voltage command v _MC ^* , the three phase voltage commands v _M ^* , The amplitudes of v _A ^* and v _C ^* are different, and the electrical phase angles are shifted from each other by 120 degrees.
On the other hand, as is clear from Equations 23 to 25 and Equations 26 to 28, amplitude commands V _MC ^* and V _AC ^* of desired two line voltages (between M and C and between A and C) are obtained. If they are the same, and the A-C line voltage command v _AC ^* is 90 degrees ahead of the _MC line voltage command v _MC ^* , then the three phase voltage commands v _M ^* , V _A ^* , v _C ^* , the amplitude of one phase voltage command is different from the amplitude of the other two phase voltage commands, and the electrical phase angle of each phase voltage command is shifted by 120 degrees from each other. It will be.

As an example, the amplitude commands V _MC ^* and V _AC ^* of the desired two line voltages are the same, and the line voltage command v _AC ^* is advanced by 90 degrees with respect to the line voltage command v _MC ^* . FIG. 10 shows a phasor diagram representing the amplitude and phase relationship of the voltage command value of power converter 100 in this case.

The phase voltage commands v _M ^* , v _A ^* , and v _C ^* obtained by the phase voltage command calculation unit 350 as described above are input to the first voltage command correction unit 400 having the same configuration as that in FIG. λ _M ^* , λ _A ^* , and λ _C ^* are calculated.
Next, the correction signal calculation means 510 in the second voltage command correction means 500 adds the modulation signals λ _M ^* , λ _A ^* , λ _C ^* and the correction signal λ ₀ ^* , as a result of FIG. 9B. As shown in FIG. 4, a correction signal λ ₀ ^{* is set} so that one of the final modulation signals λ _M ^** , λ _A ^** , and λ _C ^** becomes the same value as the maximum value or the minimum value of the carrier triangular wave ^. Is generated. The detailed operation of the correction signal calculation unit 510 will be described later.
Correction signal lambda ₀ ^* and the modulation signal ^{_{λ M *, λ A *,}} λ C * and an adder ₅₀₂ M for adding _{respectively,} 502 A, of 502 _C after construction and operation is the corresponding model on purpose the same previously described Therefore, the description is omitted.

Also in this reference embodiment, the final modulation signals λ _M ^** , λ _A ^** , and λ _C ^** are not sine waves as shown in FIG. 9B, and the phase voltage waveforms are also shown in FIG. 9C. As shown, it is no longer a sine wave. However, since the same correction signal λ ₀ ^* is added to the modulation signals λ _M ^* , λ _A ^* , λ _C ^* obtained from the target line voltage commands v _MC ^* , v _AC ^* , the power conversion device In the output line voltage of 100, the correction signal λ ₀ ^* component superimposed on each phase voltage is not canceled and does not appear, and the sinusoidal line voltages v _MC , v _AC according to the commands v _MC ^* , v _AC ^*. Can be obtained.

Next, the operation of the correction signal calculation unit 510 will be described. FIG. 8 is a flowchart for calculating the correction signal λ ₀ ^* , which is implemented in the correction signal calculation means 510.
(1) First, the absolute values of the three output phase voltage reference sine wave commands v _M0 ^* , v _A0 ^* and v _C0 ^* are calculated, and the absolute values v _M0 ^* _ABS , v _A0 ^* _ABS and v _C0 ^* _ABS are calculated. Obtain (step S21).
(2) Next, the maximum value v ₀ ^* _ABSMAX is obtained from the obtained three absolute values v _M0 ^* _ABS , v _A0 ^* _ABS , and v _C0 ^* _ABS (step S22).

(3) Further, it is determined which phase of the maximum value v ₀ ^* _ABSMAX is the absolute value of the M phase, the A phase, or the C phase, and the final modulation signal of the phase is determined as the maximum value of the carrier triangular wave. Alternatively, it is determined to be the same value as the minimum value. Specifically, if the following equation 32 is satisfied, the M-phase modulation signal λ _M ^** is determined (YES in step S23), and if the following equation 33 is satisfied, the A-phase modulation signal λ _A ^** is determined (YES in step S25). If neither of the formulas 32 and 33 is satisfied, the C-phase modulation signal λ _C ^** is determined to be the same value as the maximum value or the minimum value of the carrier triangular wave (NO in step S25).

(4) If the M phase is selected in step S23 (YES in step S23), the polarity of the M phase reference sine wave command v _M0 ^* is determined (step S24), and the M phase modulation signal λ _M ^** is transmitted to the carrier. It is determined whether it is the same as the maximum value (= 1) of the triangular wave or the same as the minimum value (= −1). Specifically, when the following Expression 34 is satisfied, the M-phase modulation signal λ _M ^** is set to be the same as the maximum value (= 1) of the carrier triangular wave (YES in step S24). The signal λ _M ^** is set to be the same as the minimum value (= −1) of the carrier triangular wave (NO in step S24).

(5) If it is selected in step S24 that the M-phase modulation signal λ _M ^** is the same as the maximum value of the carrier triangular wave (= 1), the correction signal λ ₀ ^* is calculated by Equation 35 (step S24). S24 YES, S28).

(6) If it is selected in step S24 that the M-phase modulation signal λ _M ^** is the same as the minimum value (= 1) of the carrier triangular wave, the correction signal λ ₀ ^* is calculated by Equation 36 (step S24NO, S29).

In addition, the process when the phase A is selected in step S25 (step S25 YES) and the process when the phase C is selected (step S25 NO) are the steps S26, S30, S31, or steps S27, S32, In S33, the processing is the same as the processing in which λ _M ^* and λ _M ^** in (4) and (5) are replaced with λ _A ^* and λ _A ^** or λ _C ^* and λ _C ^** .

100: Power converters 101, 102: Smoothing capacitor 103: DC power supply 200: Electric motor (induction motor)
201, 202: Winding 300: Phase voltage command calculating means 301, 302: Adder 350: Phase voltage command calculating means 351: Line voltage amplitude command calculating section 352 _M : M phase voltage amplitude command calculating section 352 _A : A phase Voltage amplitude command calculator 352 _C : C phase voltage amplitude command calculator 353 _M , 353 _A , 353 _C : Multiplier 354: Frequency command calculator 355: Electrical angle calculator 356: Phase voltage reference sine wave signal calculator 400: First voltage command correction means 401 _M , 401 _A , 401 _C : Multiplier 402: Divider 500: Second voltage command correction means 501 and 510: Correction signal calculation means 502 _M , 502 _A and 502 _C : Adder _{601 M, 601 A, 601 C} : comparator _{602 M, 602 A, 602 C} : inverter _{T MP, T MN, T AP} , T AN, T CP, T CN: half Body switch (IGBT)

Claims (2)

A first semiconductor switch series circuit configured by connecting a first semiconductor switch and a second semiconductor switch in series;
A second semiconductor switch series circuit configured by connecting a third semiconductor switch and a fourth semiconductor switch in series;
A third semiconductor switch series circuit configured by connecting a fifth semiconductor switch and a sixth semiconductor switch in series;
Connect all the DC voltage sources in parallel,
Series connection point of the first semiconductor switch and the second semiconductor switch, Series connection point of the third semiconductor switch and the fourth semiconductor switch, Series connection point of the fifth semiconductor switch and the sixth semiconductor switch Are connected to a load as output terminals of the first phase, the second phase, and the third phase, respectively,
Voltage detecting means for detecting a DC voltage of the DC voltage source;
Among the first to third voltage commands for the first phase to the third phase, voltage command generating means for generating two voltage commands having the same amplitude and the electrical phase angle shifted by 180 degrees;
First voltage command correcting means for correcting the amplitude of the first to third voltage commands according to the voltage detection value by the voltage detecting means;
Among the first to third semiconductor switch series circuits, the semiconductor switch constituting one semiconductor switch series circuit is repeatedly turned on and off, and at least one of the four semiconductor switches constituting the remaining two semiconductor switch series circuits. Second voltage command correction means for correcting the first to third voltage commands whose amplitude has been corrected by the first voltage command correction means so that the switch is kept in an on state;
A power conversion device comprising: In the power converter device according to claim 1,
The second voltage command correcting means is
Of the first to third voltage commands whose amplitude has been corrected by the first voltage command correcting means, the voltage command of the phase having the semiconductor switch for holding the ON state is the one of the semiconductor switches constituting the one semiconductor switch series circuit. A correction signal that is equal to the maximum value or the minimum value of the carrier triangular wave for generating the on / off signal is calculated, and the first to third voltages are amplitude-corrected by the first voltage command correction means. power conversion apparatus characterized by have a means for adding all of the command, respectively.

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