JP5849632B2 - Power converter - Google Patents

Description

  The present invention relates to a power conversion device, and more particularly to a power conversion device including a matrix converter.

  In recent years, a matrix converter (hereinafter also referred to as MC), which is an AC-AC direct power converter that can directly convert AC power from a commercial power source into AC power of any voltage and any frequency without going through a DC link. ) Is attracting attention.

  MC is advantageous in terms of size, life, and efficiency as compared to a conventional converter / inverter system via a DC link. Moreover, there are few power supply harmonics and regenerative operation is possible.

  An example of such MC control method is Muneaki Ishida, Masami Iwasaki, Shigeru Okuma, Koji Iwata, “Waveform Control Method of Input Power Factor Variable Sine Wave Input / Output PWM Control Cycloconverter”, Electrical Theory D, Vol. 107, No. 2, pp. 239-246, 1987 (Non-Patent Document 1). That is, the X function for controlling the phase of the input current and the Y function for controlling the phase and amplitude of the output voltage are synthesized. By performing PWM (Pulse Width Modulation) control on the signal wave obtained by this synthesis, a switching pulse for controlling each switch in the MC is obtained.

  In addition, Yoshiro Yamamoto et al., “Improvement of Pulse Pattern in Space Vector Modulation of Matrix Converter”, Electron Theory D, Vol.128, No.3, pp.176-183, 2008 (Non-Patent Document 2) The following MC control method is disclosed. That is, for the three-phase input AC voltage connected to each output phase, switching between the maximum voltage phase and the minimum voltage phase is prohibited. Specifically, the on order of the three switches connecting the three input phases and the one output phase, that is, the switching pattern, is set so that the maximum voltage phase and the minimum voltage phase are always switched via the intermediate voltage phase ( Non-patent document 2). By such switching, harmonics of the output voltage can be reduced.

Muneaki Ishida, Masami Iwasaki, Shigeru Okuma, Koji Iwata, “Waveform Control Method for Variable Input Power Factor Sine Wave Input / Output PWM Control Cycloconverter”, D. D, Vol.107, No.2, pp.239- 246, 1987 Yoshiro Yamamoto et al., “Improvement of Pulse Pattern in Space Vector Modulation of Matrix Converter”, Electrical Engineering D, Vol.128, No.3, pp.176-183,2008

  By the way, it is necessary to prepare a plurality of types of switching patterns described in Non-Patent Document 2 according to the magnitude relationship of the three-phase input voltages at each timing.

  Further, the frequency of the carrier wave in the PWM control of the MC is generally synchronized with the sampling frequency for sampling the MC input voltage or the like, or set to an integral multiple of the sampling frequency.

  In this case, for example, in a configuration in which a triangular wave carrier having an amplitude of 1 is used in PWM control, the instantaneous value of the input voltage is sampled, and based on this sampling result, the timing at which the carrier wave level becomes the minimum zero, or the carrier wave The mode is switched in synchronism with one of the timings at which the level of 1 reaches the maximum.

  However, depending on the combination of the switching pattern before switching and the switching pattern after switching, switching between the maximum voltage phase and the minimum voltage phase may be performed at the mode switching timing.

  Such switching causes switching loss and voltage errors due to commutation, that is, switching between phases. Due to this switching loss, the efficiency of the device is reduced, and the cooling device is enlarged, which hinders the reduction in size and weight. Further, this voltage error becomes a factor in generating harmonics in the output voltage.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to achieve power conversion capable of suppressing the occurrence of switching loss and voltage error by appropriately controlling each switch in a matrix converter. Is to provide a device.

  In order to solve the above-described problems, a power converter according to an aspect of the present invention includes a matrix converter for converting AC power supplied from a plurality of phases of power into a plurality of phases of AC power and supplying the AC power to a load. A control unit for controlling the matrix converter, and the matrix converter is provided for each of the power supplies, and for transmitting the AC power supplied from the corresponding power supply to the load by turning it on. The control unit includes a plurality of switches, and the control unit selectively turns on the plurality of switches according to a predetermined order, has a plurality of modes having different orders, and is supplied with the AC voltage from the plurality of phases of power. The above modes are switched based on the level relationship between the levels, and the same is applied during the period before and after the mode switching timing. Switch setting the switching timing so that the ON state.

  With such a configuration, it is possible to prevent the occurrence of switching associated with mode switching, and thus switching loss can be reduced. Thereby, the capacity | capacitance of a cooling device can be reduced and it can contribute to the size reduction and weight reduction of an apparatus by extension. Moreover, although an output voltage error occurs during the commutation period by performing switching, this output voltage error can be reduced and output voltage harmonics can be reduced by reducing the number of times of switching in the power conversion operation. .

  Preferably, the control unit calculates a control value indicating a rate at which the plurality of switches are turned on in one cycle of the carrier wave, and turns on based on a comparison result between the carrier wave and each control value. The switch to be selected is selected, and the mode is switched according to the timing of the carrier wave.

  With such a configuration, each switch in the matrix converter can be appropriately PWM controlled, and mode switching can be performed at an appropriate timing according to the PWM control.

  More preferably, the control unit has three or more modes, and switches the mode according to both the timing when the level of the carrier wave reaches the maximum value and the timing when the carrier wave level reaches the minimum value.

  As described above, the configuration in which the mode is switched at the timing at which the level of the carrier wave is maximized or minimized can simplify the mode switching control as compared with the configuration in which the mode is switched at other timings.

  Preferably, the predetermined sequence is such that at least one of the AC voltages transmitted to the load via the switch before and after the switch to be turned on is changed to the plurality of phases. The AC voltage is set to be other than the AC voltage having the maximum level and the AC voltage having the minimum level among the AC voltages respectively supplied from the power sources.

  With such a configuration, the ON order of the plurality of switches that respectively connect the plurality of input voltage phases and each output phase is set so that the maximum voltage phase and the minimum voltage phase are always switched via the intermediate voltage phase, In a configuration that reduces harmonics of the output voltage, switching associated with mode switching can be prevented. Further, by suppressing the occurrence of a voltage error due to switching loss and commutation, it is possible to suppress a reduction in the efficiency of the device, achieve a reduction in size and weight, and reduce harmonics of the output voltage.

  According to the present invention, it is possible to suppress occurrence of switching loss and voltage error by appropriately controlling each switch in the matrix converter.

It is a figure which shows the structure of the power supply system which concerns on embodiment of this invention. It is a figure which shows the equivalent circuit for the output 1 phase of a matrix converter in the power converter device which concerns on embodiment of this invention. It is a figure which shows an example of the switching pattern about the output 1 phase of a matrix converter in the power converter device which concerns on embodiment of this invention. It is a figure which shows an example of mode division in the power converter device which concerns on embodiment of this invention. It is a figure which shows an example of the switching pattern in the power converter device which concerns on embodiment of this invention. It is a figure which shows an example of how to obtain | require the switching pattern in the power converter device which concerns on embodiment of this invention. It is a figure which shows an example of the switching operation from mode I to mode II. It is a figure which shows an example of the switching operation from mode II to mode III. It is a figure which shows an example of the timing of mode switching in the power converter device which concerns on embodiment of this invention. It is a figure which shows the other example of the switching pattern in the power converter device which concerns on embodiment of this invention. It is a figure which shows the other example of the timing of mode switching in the power converter device which concerns on embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

[Configuration and basic operation]
FIG. 1 is a diagram showing a configuration of a power supply system according to an embodiment of the present invention.

  Referring to FIG. 1, power supply system 201 includes AC power supplies EU, EV, and EW connected to neutral line NL, power conversion device 101, and loads LA, LB, and LC. The power conversion device 101 includes a matrix converter 1, an input filter 2, an output filter 3, a measurement unit 4, and a control unit 5. Matrix converter 1 includes bidirectional switches Sa1, Sa2, Sa3, Sb1, Sb2, Sb3, Sc1, Sc2, and Sc3. The loads LA, LB, LC are, for example, star-connected.

  The power conversion device 101 is, for example, a three-phase three-wire system, and generates a plurality of phases of AC voltage or current having an arbitrary frequency and an arbitrary amplitude from a plurality of phases of AC power whose frequency and amplitude vary. In other words, the power conversion device 101 uses the U-phase, V-phase, and W-phase AC power supplied from each of the AC power sources EU, EV, and EW as the A phase, B phase, and C phase having an arbitrary frequency and arbitrary amplitude. And is supplied to the loads LA, LB, and LC, respectively.

  The input filter 2 is provided between the AC power supplies EU, EV, EW and the matrix converter 1.

  The output filter 3 is provided between the matrix converter 1 and the loads LA, LB, and LC.

  In the matrix converter 1, a set of switches is provided for each AC power supply, and the AC power supplied from the corresponding AC power supply is transmitted to a one-phase load by being turned on. This set of switches is provided for each phase of the load. That is, the matrix converter 1 includes a set of bidirectional switches Sa1, Sa2, Sa3 corresponding to the A phase, a set of bidirectional switches Sb1, Sb2, Sb3 corresponding to the B phase, and a bidirectional switch Sc1 corresponding to the C phase. , Sc2 and Sc3.

  The bidirectional switch Sa1 is connected between the U-phase output of the input filter 2 and the A-phase input of the output filter 3. The bidirectional switch Sa2 is connected between the V-phase output of the input filter 2 and the A-phase input of the output filter 3. The bidirectional switch Sa3 is connected between the W-phase output of the input filter 2 and the A-phase input of the output filter 3. The bidirectional switch Sb1 is connected between the U-phase output of the input filter 2 and the B-phase input of the output filter 3. The bidirectional switch Sb2 is connected between the V-phase output of the input filter 2 and the B-phase input of the output filter 3. The bidirectional switch Sb3 is connected between the W-phase output of the input filter 2 and the B-phase input of the output filter 3. The bidirectional switch Sc1 is connected between the U-phase output of the input filter 2 and the C-phase input of the output filter 3. The bidirectional switch Sc2 is connected between the V-phase output of the input filter 2 and the C-phase input of the output filter 3. The bidirectional switch Sc3 is connected between the W-phase output of the input filter 2 and the C-phase input of the output filter 3.

  Each of the bidirectional switches Sa1, Sa2, Sa3, Sb1, Sb2, Sb3, Sc1, Sc2, and Sc3 is usually configured by combining two semiconductor switches such as an IGBT (Insulated Gate Bipolar Transistor). However, since semiconductor elements such as IGBTs do not have reverse withstand voltage, generally two circuits in which IGBTs and diodes are connected in reverse parallel, that is, connected in parallel so that their conduction directions are opposite to each other, are combined in series. A circuit configuration is used. Note that when a semiconductor switch having reverse breakdown voltage is used, a diode is not necessary, and two semiconductor switches may be connected in reverse parallel.

  Input filter 2 attenuates noise of a predetermined frequency or more included in U-phase, V-phase, and W-phase AC power received from AC power supplies EU, EV, and EW, respectively, and outputs the attenuated AC power to matrix converter 1. To do.

  Matrix converter 1 converts input AC power received from AC power sources EU, EV, and EW into output AC power of a plurality of phases and outputs the output AC to loads LA, LB, and LC. Specifically, matrix converter 1 turns on / off bidirectional switches Sa1, Sa2, Sa3, Sb1, Sb2, Sb3, Sc1, Sc2, and Sc3 based on control signals G1 to G9 received from control unit 5, respectively. Thus, the U-phase, V-phase, and W-phase AC power that has passed through the input filter 2 is converted into A-phase, B-phase, and C-phase AC power having an arbitrary frequency and an arbitrary voltage amplitude, and the output filter 3 is supplied. Output.

  Output filter 3 attenuates noise of a predetermined frequency or more included in A-phase, B-phase, and C-phase AC power received from matrix converter 1, and outputs the attenuated AC power to loads LA, LB, and LC, respectively. .

  Here, the frequency of noise attenuated by the output filter 3 is appropriately changed according to the specifications of the power supply system 201, and is higher than the frequency of AC power to be supplied to the loads LA, LB, LC, for example.

Measurement unit 4 includes a current detection unit (not shown), input AC currents i _u , i _v , i _w received by matrix converter 1 from AC power sources EU, EV, EW, and output AC current i _a output from matrix converter 1. , I _b , i _c are detected, and a signal indicating the detection result is output to the control unit 5.

The measurement unit 4 includes a voltage detection unit (not shown). The AC power sources EU, EV, and EW output the power source AC voltages v _u0 , v _v0 , and v _{w0 to} the matrix converter 1. The input AC voltages v _u , v _v , v _w received from the AC power sources EU, EV, EW and the output AC voltages v _a , v _b , v _c of the matrix converter 1 are detected, and signals indicating the detection results are transmitted to the control unit. Output to 5.

  The control unit 5 generates control signals G1 to G9 based on the detection result of the measurement unit 4, and outputs them to the bidirectional switches Sa1, Sa2, Sa3, Sb1, Sb2, Sb3, Sc1, Sc2, Sc3 in the matrix converter 1, respectively. By doing so, the matrix converter 1 is controlled.

The power supply AC voltages v _u0 , v _v0 , v _w0 and the input AC voltages v _u , v _v , v _w are expressed by the following equations.

In the equations (1) and (2), ω is the angular frequency of the AC power supplies EU, EV, EW, and V _S is the voltage amplitude before the filter, that is, the amplitude of the power supply AC voltages v _u0 , v _v0 , v _w0 . , V is the voltage amplitude after filtering, that is, the amplitude of the input AC voltages v _u , v _v , v _w . Further, δ is a phase delay angle generated by the input filter 2.

The control unit 5 updates the on-duty of each switch in the matrix converter 1 for each sampling period T _s .

Here, consider the control functions a _{1 to} c ₃ for formulating the control law of each switch in the matrix converter 1.

For example the ON percentage ie on-duty in the sampling period of the bidirectional switch Sa1 is defined as a _1, it is defined as shown in the following equation a _1.

Since the power converter 101 is a direct power converter, a short circuit on the input side and an open side on the output side are not allowed. For this reason, the following constraint conditions are required.

ただし、Ｙ₁＋Ｙ₂＋Ｙ₃＝０ The control unit 5 performs control such that the control function is represented by the following expression.

However, Y ₁ + Y ₂ + Y ₃ = 0

Here, the functions X ₁ , X ₂ , and X ₃ in the expression (6) are expressed by the following expressions and are called input-side functions.

In equation (7), ψ _S is a command value of the phase of the input alternating current with respect to the input alternating voltage of the matrix converter 1, and A is the voltage amplitude modulation rate.

In addition, the functions Y ₁ , Y ₂ , and Y ₃ in the expression (6) are called output side functions, and the output side functions represent a command waveform of the output voltage.

Further, h _u , h _v , and h _w in the equation (6) are functions introduced to satisfy the constraint condition of the equation (4). In this case, the period T _s output AC voltage at v _a, v _b, the average value of v _c is (2), (6) and (7), as follows.

In the equation (8), the first term is the output voltage of the matrix converter 1 to be obtained. In the output voltage, the waveforms of the output side functions Y ₁ , Y ₂ and Y ₃ appear as they are. For this reason, the output side function becomes a command waveform of the output voltage. The second term is a neutral point potential component at the load end that appears by the functions h _u , h _v , and h _w and does not appear in the output line voltage. The method for deriving these functions h _u , h _v and h _w is the same as the method described in Non-Patent Document 1.

[Operation]
Next, the power conversion operation of the power conversion device according to the embodiment of the present invention will be described with reference to the drawings.

The control unit 5 performs PWM control of each switch in the matrix converter 1. That is, the control unit 5 compares the control functions a _{1 to} c ₃ obtained by the control algorithm with a carrier wave such as a triangular wave carrier or a sawtooth wave carrier to generate a switching pulse. Then, control unit 5 turns on / off each switch in matrix converter 1 based on the generated switching pulse.

  Below, the operation | movement about the input 3 phase and output 1 phase of the matrix converter 1 is demonstrated typically. The operations for the other output phases are the same as the operations described below.

[Switching control in mode]
FIG. 2 is a diagram showing an equivalent circuit for one phase of the output of the matrix converter in the power conversion device according to the embodiment of the present invention. FIG. 2 shows a connection relationship between one output phase of the matrix converter 1, that is, the A phase, and three input phases, that is, the U phase, the V phase, and the W phase.

  FIG. 3 is a diagram showing an example of a switching pattern for one output phase of the matrix converter in the power conversion device according to the embodiment of the present invention.

For example, with respect to the control functions a _{1 to} a ₃ obtained by the control algorithm described above, the control unit 5 performs PWM control using the timing at which the triangular wave carrier reaches the minimum value as the update timing of the sampling data. At this update timing, the values of the control functions a _{1 to} a ₃ are updated. In this case, the switching pulses of the bidirectional switches Sa1 to Sa3 connected to the A phase are as shown in FIG.

That is, when the level of the carrier wave CS is a ₁ smaller than the bidirectional switch Sa1 is turned on, the bidirectional switch Sa2 is turned on when the level of the carrier wave CS is large a ₁ + a ₂ smaller than a _1, When the level of the carrier wave CS is larger than a ₁ + a ₂ , the bidirectional switch Sa3 is turned on.

  Therefore, the order in which the switches are turned on within one carrier cycle is the order of Sa1, Sa2, Sa3, Sa2, and Sa1.

  In the power conversion device 101, the switching pattern is such that at least one of the AC voltages transmitted to the one-phase load via the switch before and after the switch to be turned on is a plurality of phases. The AC voltage is set so as to be other than the AC voltage having the maximum level and the AC voltage having the minimum level among the AC voltages respectively supplied from the AC power source. Specifically, in the power conversion device 101, as in the technique described in Non-Patent Document 2, the on-order of three switches that connect the three input phases and the one output phase, that is, the switching pattern, is set to the maximum voltage phase and Set so that the minimum voltage phase is switched via the intermediate voltage phase.

  As such a control method, an example employ | adopted in the power converter device 101 is demonstrated.

  FIG. 4 is a diagram showing an example of mode division in the power conversion device according to the embodiment of the present invention.

Referring to FIG. 4, in power conversion device 101, the switching pattern is divided into six modes, Mode I to Mode VI, depending on the magnitude relationship of the input AC voltage. Here, the frequency of the input AC voltages v _u , v _v and v _w is, for example, several tens of Hz, and the frequency of the carrier wave is, for example, several tens of kHz. That is, in the period from the start to the end of each mode, the control functions a _{1 to} a ₃ are updated a plurality of times, and the on-duty of each switch in the matrix converter 1 is switched.

  Of the three-phase input AC voltages, the maximum voltage phase is Vmax, the intermediate voltage phase is Vmid, and the minimum voltage phase is Vmin. Then, each switch of the matrix converter 1 is turned on so that the order of the three-phase input AC voltages connected to the output phase is Vmin, Vmid, Vmax, Vmid, and Vmin in one carrier cycle in each mode. Determine the order.

For example, when the magnitude relation of the input AC voltage is in the mode I state, the magnitude relation of the input AC voltage is Vmax = v _u , Vmid = v _w , Vmin = v _v . In mode I, in order to ensure that the maximum voltage phase and the minimum voltage phase are switched via the intermediate voltage phase, the order of the input AC voltage connected to the output A phase is v _v , v _w , v _u , v _w, and the order of _v v.

  That is, in mode I, the bidirectional switch Sa2, the bidirectional switch Sa3, the bidirectional switch Sa1, the bidirectional switch Sa3, and the bidirectional switch Sa2 are turned on in this order.

  FIG. 5 is a diagram illustrating an example of a switching pattern in the power conversion device according to the embodiment of the present invention.

  Referring to FIG. 5, in the output phase, the state in which the switch connected to the input U phase is on is “1”, the state in which the switch connected to the input V phase is on is “2”, and the input The state in which the switch connected to the W phase is turned on is “3”.

  For example, when the magnitude relationship of the input AC voltage is in the mode II state, the switching order within one carrier cycle is the order of 3, 2, 1, 2, 3. That is, in the circuit shown in FIG. 2, the bidirectional switch Sa3, the bidirectional switch Sa2, the bidirectional switch Sa1, the bidirectional switch Sa2, and the bidirectional switch Sa3 are turned on in this order.

  The setting of the switching pattern in each mode can be easily realized by changing the order of the control functions to be compared with the carrier wave when performing PWM control.

  As a specific example, a method for obtaining the output A-phase switching pattern in mode I will be described with reference to the drawings.

  FIG. 6 is a diagram illustrating an example of how to obtain a switching pattern in the power conversion device according to the embodiment of the present invention.

Referring to FIG. 6, the relationship between the switches to be turned on and the control functions a _{1 to} a ₃ is set as follows. That is, when the level of the carrier wave CS is a ₂ smaller than the bidirectional switch Sa2 is turned on, the bidirectional switch Sa3 is turned on when the level of the carrier wave CS is large a ₂ + a ₃ smaller than a _2, When the level of the carrier wave CS is larger than a ₂ + a ₃ , the bidirectional switch Sa1 is turned on.

  Therefore, the order in which the bidirectional switch is turned on in one carrier cycle in mode I is the order of Sa2, Sa3, Sa1, Sa3, Sa2.

Thus, the above switching pattern can be obtained by comparing the three values of a ₂ , a ₂ + a ₃ and a ₂ + a ₃ + a ₁ (= 1) with the carrier wave. That is, various switching patterns can be obtained by changing the comparison target of the carrier wave in each mode.

[Switching between modes]
As described above, the frequency of the carrier wave in the PWM control of the MC is generally synchronized with the sampling frequency for sampling the MC input voltage or the like, or set to an integral multiple of the sampling frequency.

  In this case, for example, in a configuration in which a triangular wave carrier having an amplitude of 1 is used in PWM control, the instantaneous value of the input AC voltage is sampled, and based on the sampling result, the timing TL at which the carrier wave level becomes the minimum zero, or The mode is switched in synchronization with any one of the timings TH at which the level of the carrier wave becomes 1 at the maximum.

  Here, as described with reference to FIG. 5, the on order of the three switches that respectively connect the three input phases and the one output phase is switched so that the maximum voltage phase and the minimum voltage phase are always switched via the intermediate voltage phase. The following problems occur in the configuration to be set.

  That is, for example, when switching from mode I to mode II is performed at the timing TL, switching that switches from the ON state of the bidirectional switch Sa2 to the ON state of the bidirectional switch Sa3 occurs at the moment when the mode is switched. .

  Such switching causes switching loss and voltage errors due to commutation, that is, switching between phases. Due to this switching loss, the efficiency of the device is reduced, and the cooling device is enlarged, which hinders the reduction in size and weight. Further, this voltage error becomes a factor in generating harmonics in the output voltage.

  Therefore, the power conversion device according to the embodiment of the present invention solves the above-described problem by performing the following switching control.

  That is, the control unit 5 alternately turns on a plurality of switches in the set of switches of the matrix converter 1 according to a predetermined order, and has a plurality of modes having different orders. The control unit 5 switches modes based on the magnitude relationship between the levels of the AC voltages supplied from the AC power sources EU, EV, and EW, respectively. Then, the control unit 5 is configured so that the same switch is turned on in the period before and after the mode switching timing, that is, the switch that is turned on immediately before the mode switching timing and the switch that is turned on immediately after the mode switching timing are the same. Set the switching timing.

More specifically, the control unit 5 calculates the control values a _{1 to} a ₃ indicating the ratios at which the plurality of switches are turned on in one cycle of the carrier wave, that is, the on-duty, respectively. Based on the comparison result, the switch to be turned on is selected, and the mode is switched according to the timing of the carrier wave. For example, the control unit 5 has three or more modes, and switches modes according to both the timing at which the level of the carrier wave reaches the maximum value and the timing at which the carrier wave level reaches the minimum value.

  Specifically, the control unit 5 is the timing TL at which the carrier wave reaches the minimum value of the amplitude, or the timing TH at which the carrier wave reaches the maximum value of the amplitude, and the switching source mode and the switching destination mode. The mode is switched at the timing when the in-phase switch is turned on.

  For example, as shown in FIG. 4, in mode I and mode II, the maximum voltage phase is common to the U phase. Similarly, in mode III and mode IV, the maximum voltage phase is common to the V phase, and in mode V and mode VI, the maximum voltage phase is common to the W phase.

  When the timing when the carrier wave reaches the minimum value is set as the update timing of the sampling data in the PWM control, and switching is performed according to the switching order shown in FIG. 5, the maximum voltage is reached when the carrier wave reaches the maximum value. The bidirectional switch corresponding to the phase is always turned on.

  Using this characteristic, the control unit 5 reaches the maximum value of the carrier wave when shifting from mode I to mode II, when shifting from mode III to mode IV, and when shifting from mode V to mode VI. The mode is switched at the timing.

Here, the input AC voltage at the timing when the level relationship of the levels of the input AC voltages v _u , v _v , and v _w supplied from the AC power sources EU, EV, and EW changes, that is, at the timing shown by the dotted line in FIG. Ideally, sampling is performed for v _u , v _v , and v _w and the mode is immediately switched based on the sampling result.

In practice, however, the sampling timing often deviates from the timing at which the level relationship of the levels of the input AC voltages v _u , v _v and v _w changes. In this case, the control unit 5 detects the timing TL when the level of the carrier wave becomes the minimum zero after detecting that the level relationship of the levels of the input AC voltages v _u , v _v , v _w has changed, or the carrier wave. The mode is switched at any timing TH at which the level of 1 reaches the maximum. That is, the mode is switched at the maximum after one cycle of the carrier wave from the timing when the magnitude relation of the levels of the input AC voltages v _u , v _v , v _w changes. For example, the timing of the detection is after the timing shown by the dotted line in FIG.

The control unit 5, the input AC voltage v _u, v _v, v is not limited to the configuration to detect that the level magnitude of the _w is changed, the input AC voltage v _u, v _v, v difference in the level of _w May be configured to switch the mode by detecting that is less than a predetermined threshold. For example, the detection timing in this case is before the timing indicated by the dotted line in FIG.

Further, the sampling period of the input AC voltages v _u , v _v , and v _w may be set to a length obtained by adding a predetermined time to one mode period, for example, 1/6 period of the input AC voltage in FIG. For example, it may be set to (one mode period + one carrier wave period). As a result, it is possible to increase the possibility that the mode switching can be immediately performed by detecting the change in the magnitude relationship between the levels of the input AC voltages v _u , v _v and v _w .

  FIG. 7 is a diagram illustrating an example of the switching operation from mode I to mode II. FIG. 7 shows an example of mode switching synchronized with the timing when the carrier wave reaches the maximum value.

  Referring to FIG. 7, control unit 5 sets the update timing of sampling data to timing TL when the carrier wave reaches the minimum value.

  In this case, it is not necessary to update the sampling data at the time of transition from mode I to mode II, and mode switching, that is, only switching pattern change is performed at timing TH when the carrier wave reaches the maximum value.

  Further, as shown in FIG. 4, in mode II and mode III, the minimum voltage phase is common to the W phase. Similarly, in mode IV and mode V, the minimum voltage phase is common to the U phase, and in mode VI and mode I, the minimum voltage phase is common to the V phase.

  When the timing at which the carrier wave reaches the minimum value is set as the update timing of the sampling data in the PWM control, and switching is performed according to the switching order of FIG. 5, when the carrier wave reaches the minimum value, the minimum voltage phase The bidirectional switch corresponding to is always turned on.

  Using this characteristic, the control unit 5 reaches the minimum value at the time of transition from mode II to mode III, transition from mode IV to mode V, and transition from mode VI to mode I. The mode is switched at the timing.

  FIG. 8 is a diagram illustrating an example of the switching operation from mode II to mode III. FIG. 8 shows an example of mode switching synchronized with the timing when the carrier wave reaches the minimum value.

  Referring to FIG. 8, control unit 5 sets the update timing of the sampling data to timing TL when the carrier wave reaches the minimum value.

  In this case, the sampling data is updated and the mode is switched at the same time TL when the carrier wave reaches the minimum value.

  The mode switching timings set as described above are summarized as shown in FIG.

  FIG. 9 is a diagram illustrating an example of mode switching timing in the power conversion device according to the embodiment of the present invention.

  Referring to FIG. 9, control unit 5 sets timing TH as the switching timing from mode I to mode II, the switching timing from mode III to mode IV, and the switching timing from mode V to mode VI. At the time of switching, the input voltage phase connected to the ON state, that is, the output phase becomes the maximum voltage phase Vmax. Further, the control unit 5 sets the timing of switching from mode II to mode III, the timing of switching from mode IV to mode V, and the timing of switching from mode VI to mode I as timing TL. At the time of switching, the input voltage phase connected to the ON state, that is, the output phase becomes the minimum voltage phase Vmin.

  By setting the mode switching timing in this manner, it is possible to prevent the occurrence of switching due to the mode switching, and therefore it is possible to suppress the occurrence of loss and voltage error due to switching.

[Modification]
The control unit 5 determines the order of the three-phase input AC voltage connected to the output phase in one cycle of the carrier in each mode as the order of the maximum voltage phase, the intermediate voltage phase, the minimum voltage phase, the intermediate voltage phase, and the maximum voltage phase. It may be configured as follows. Even in such a configuration, it is possible to prevent the occurrence of switching due to mode switching by setting the mode switching timing similarly to the above-described example.

  FIG. 10 is a diagram illustrating another example of the switching pattern in the power conversion device according to the embodiment of the present invention. The way of viewing the figure is the same as in FIG.

  Referring to FIG. 10, for example, when the magnitude relation of the input AC voltage is in the mode I state, the switching order within one carrier period is 1, 3, 2, 3, 1. That is, in the circuit shown in FIG. 2, the bidirectional switch Sa1, the bidirectional switch Sa3, the bidirectional switch Sa2, the bidirectional switch Sa3, and the bidirectional switch Sa1 are turned on in this order. Further, when the magnitude relationship of the input AC voltage is in the mode II state, the switching order within one carrier cycle is 1, 2, 3, 2, 1. That is, in the circuit shown in FIG. 2, the bidirectional switch Sa1, the bidirectional switch Sa2, the bidirectional switch Sa3, the bidirectional switch Sa2, and the bidirectional switch Sa1 are turned on in this order.

  The timing at which the carrier wave reaches the minimum value is used as the update timing of the sampling data in PWM control. When switching is performed according to the switching sequence of FIG. 5, when the carrier wave reaches the minimum value, the minimum voltage phase is supported. The bidirectional switch is always turned on.

  Using this characteristic, the control unit 5 uses this characteristic when the carrier wave reaches the minimum value when shifting from mode I to mode II, when shifting from mode III to mode IV, and when shifting from mode V to mode VI. The mode is switched at the timing.

  Further, when the timing at which the carrier wave reaches the minimum value is set as the update timing of the sampling data in the PWM control, and switching is performed according to the switching order of FIG. 5, when the carrier wave reaches the maximum value, the maximum voltage phase The bidirectional switch corresponding to is always turned on.

  Using this characteristic, the control unit 5 reaches the maximum value of the carrier wave at the time of transition from mode II to mode III, at the time of transition from mode IV to mode V, and at the time of transition from mode VI to mode I. The mode is switched at the timing.

  FIG. 11 is a diagram illustrating another example of the mode switching timing in the power conversion device according to the embodiment of the present invention.

  Referring to FIG. 11, control unit 5 sets timing TL as the switching timing from mode I to mode II, the switching timing from mode III to mode IV, and the switching timing from mode V to mode VI. At the time of switching, the input voltage phase connected to the ON state, that is, the output phase becomes the minimum voltage phase Vmin. In addition, the control unit 5 sets timing TH as the switching timing from mode II to mode III, the switching timing from mode IV to mode V, and the switching timing from mode VI to mode I. At the time of switching, the input voltage phase connected to the ON state, that is, the output phase becomes the maximum voltage phase Vmax.

  By setting the mode switching timing in this manner, it is possible to prevent the occurrence of switching due to the mode switching, and therefore it is possible to suppress the occurrence of loss and voltage error due to switching.

  By the way, in the matrix converter, depending on the combination of the switching pattern before switching and the switching pattern after switching, switching between the maximum voltage phase and the minimum voltage phase may be performed at the mode switching timing. Such switching causes switching losses and voltage errors due to commutation, ie, phase-to-phase switching. Due to this switching loss, the efficiency of the device is reduced, and the cooling device is enlarged, which hinders the reduction in size and weight. In addition, this voltage error causes a harmonic in the output voltage.

  In contrast, in the power conversion device according to the embodiment of the present invention, control unit 5 alternatively turns on a plurality of switches for each input phase in matrix converter 1 according to a predetermined order, and this order is different. Has multiple modes. The control unit 5 switches modes based on the magnitude relationship between the levels of the AC voltages supplied from the AC power sources EU, EV, and EW, respectively. And the control part 5 sets a switching timing so that the same switch may be in an ON state in the period before and behind including the switching timing of a mode.

  With such a configuration, it is possible to prevent the occurrence of switching associated with mode switching, and thus switching loss can be reduced. Thereby, the capacity | capacitance of a cooling device can be reduced and it can contribute to the size reduction and weight reduction of an apparatus by extension. Moreover, although an output voltage error occurs during the commutation period by performing switching, this output voltage error can be reduced and output voltage harmonics can be reduced by reducing the number of times of switching in the power conversion operation. .

  Moreover, in the power converter device which concerns on embodiment of this invention, the control part 5 each calculates the control value which shows the ratio in which the said some switch will be in an ON state in 1 period of a carrier wave. Then, the control unit 5 selects a switch to be turned on based on the comparison result between the carrier wave and each control value, and switches the mode according to the timing of the carrier wave.

  With such a configuration, each switch in the matrix converter 1 can be appropriately PWM controlled, and mode switching can be performed at an appropriate timing according to the PWM control.

  In the power conversion device according to the embodiment of the present invention, the control unit 5 has three or more on-order modes of the plurality of switches, and sets the timing and minimum value of the carrier wave level to the maximum value. The mode is switched according to both timings.

  As described above, the configuration in which the mode is switched at the timing at which the level of the carrier wave is maximized or minimized can simplify the mode switching control as compared with the configuration in which the mode is switched at other timings.

  In the power conversion device according to the embodiment of the present invention, the turn-on order of the plurality of switches is the alternating current transmitted to the one-phase load via the switch before and after the switch to be turned on is changed. Among the voltages, at least one of the AC voltages is set to be other than the AC voltage having the maximum level and the AC voltage having the minimum level among the AC voltages respectively supplied from the AC power supplies of a plurality of phases.

  With such a configuration, the ON order of the plurality of switches that respectively connect the plurality of input voltage phases and each output phase is set so that the maximum voltage phase and the minimum voltage phase are always switched via the intermediate voltage phase, In a configuration that reduces harmonics of the output voltage, switching associated with mode switching can be prevented. Further, by suppressing the occurrence of a voltage error due to switching loss and commutation, it is possible to suppress a reduction in the efficiency of the device, achieve a reduction in size and weight, and reduce harmonics of the output voltage.

  In addition, although the power converter device which concerns on embodiment of this invention was set as the structure provided with the measurement part 4, it is not limited to this. The measurement unit 4 may be configured to be provided outside the power conversion device 101.

  The above embodiment should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 Matrix converter 2 Input filter 3 Output filter 4 Measurement part 5 Control part 101 Power converter 201 Power supply system EU, EV, EW AC power supply LA, LB, LC Load NL Neutral line Sa1, Sa2, Sa3, Sb1, Sb2, Sb3 , Sc1, Sc2, Sc3 bidirectional switch

Claims (4)

A matrix converter for converting AC power supplied from a plurality of phases of power into a plurality of phases of AC power and supplying it to a load;
A controller for controlling the matrix converter,
The matrix converter is
A plurality of switches are provided for each of the power supplies, and the AC power supplied from the corresponding power supplies is transmitted to the load by being turned on.
The control unit selectively turns on the plurality of switches according to a predetermined order, has a plurality of modes in different orders, and has a magnitude relationship between levels of AC voltages respectively supplied from the plurality of phases of power. The power conversion device that performs switching of the mode based on the switching timing and sets the switching timing so that the same switch is turned on in a period before and after the switching timing of the mode.   The control unit calculates a control value indicating a rate at which the plurality of switches are turned on in one cycle of a carrier wave, and turns on based on a comparison result between the carrier wave and each control value. The power converter according to claim 1, wherein a switch is selected and the mode is switched according to the timing of the carrier wave.   3. The power conversion device according to claim 2, wherein the control unit has three or more modes and switches the mode according to both a timing at which the level of the carrier wave reaches a maximum value and a timing at which the carrier wave level reaches a minimum value. .   In the predetermined sequence, at least one of the AC voltages transmitted to the load through the switch before and after the switch that is turned on is changed is supplied from the plurality of phases of power. 4. The power conversion device according to claim 1, wherein the power conversion device is set so as to be other than an AC voltage having a maximum level and an AC voltage having a minimum level among the AC voltages respectively supplied. 5. .

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