JP4831303B2 - AC / AC direct converter controller - Google Patents

Description

  The present invention relates to a semiconductor power converter that converts a multiphase AC voltage into a multiphase AC voltage having an arbitrary magnitude and frequency by turning on and off a semiconductor switching element, and more particularly, an AC AC direct current that does not have a large energy buffer. In a converter, it is related with the control apparatus characterized by the commutation method for preventing a power supply short circuit.

  In general, an AC / AC direct converter is constituted by an AC switch capable of controlling a bidirectional current. However, switching that causes a power supply short circuit and a load end opening needs to be avoided for the following reason. In other words, an excessive short-circuit current generated by a power supply short-circuit may damage the switch. Also, in the case of an inductive load, if the load end is opened, the circulation path of the energy stored in the load is lost, which is excessive. This is because an excessive surge voltage is generated, leading to destruction of the switch.

Here, a case where the most common three-phase AC power supply is used as the multiphase AC power supply and a matrix converter capable of frequency conversion is used as the direct converter will be described as an example.
FIG. 11A shows a circuit for one phase (U phase) on the output side of the matrix converter.
In FIG. 11A, v _max is the maximum voltage phase of the three-phase AC power supply (hereinafter also simply referred to as the maximum phase), v _mid is the intermediate voltage phase (the same intermediate phase), and v _min is the minimum voltage phase (the same minimum phase). In the following description, the maximum voltage, the intermediate voltage, and the minimum voltage are also represented by v _max , v _mid , and v _min , respectively.

The AC switches S ₁ , S ₂ , S ₃ are two unidirectional switches S _1a , S _1b , S _{2a / b} , S _{2b / a} , S _3a , S _3b such as an IGBT that can control a current in one direction, respectively. The switches S _1a and S _3a operate in an IGBT mode (a mode in which a current flows simultaneously with the gate being turned on while a forward voltage is applied between the collector and the emitter), and the switches S _1b and S _3b It operates in a freewheeling diode mode (a mode in which a reverse voltage is applied between the collector and the emitter, and a forward voltage is applied and current does not flow unless the gate is turned on). The switches S _{2a / b} and S _{2b / a} are different from each other in IGBT mode, free-wheeling diode, depending on whether the AC switch S ₂ operates in the lower arm or the upper arm in relation to the other AC switches S ₁ and S _3. Since any of the modes operates, the subscripts are written as a / b and b / a.

Here, FIG. 11B is a schematic overall configuration diagram of the matrix converter, and a switch group S connected between the three-phase AC input terminals R, S, T and the output terminals U, V, W. _{It consists of R 1} , S _S and S _T. Each switch group S _R , S _S , S _T is composed of three AC switches. For example, the AC switches S _RU , S connected between the input terminals R, S, T and the output terminal U, respectively. _{SU 1} and S _TU correspond to the AC switches S ₁ , S ₂ , and S ₃ in FIG. That is, the maximum phase is R phase, the intermediate phase is S phase, if the minimum phase T phase, AC switch _{S 1} in FIG. 11 (a) to _{S RU} in FIG 11 (b), _{S 2} to _{S SU} , S ₃ respectively corresponds to S _TU .

When commutation is performed between the AC switches S ₁ , S ₂ , and S ₃ in FIG. 11A, each unidirectional switch is controlled so that the power supply short circuit and the load end opening do not occur as described above. There is a need. For this purpose, the magnitude of the voltage applied to the AC switch of each phase is detected, and it is determined whether the commutation is from a phase with a large voltage to a small phase or from a phase with a small power supply voltage to a large phase. It is necessary to discriminate and generate a commutation pattern according to each mode.

FIG. 12 shows a PWM pulse (PWM pattern) of each switch when commutation is performed between the maximum phase and the intermediate phase, and FIG. 13 is a diagram when commutation is performed between the intermediate phase and the minimum phase. The PWM pulse of each switch is shown.
For example, when commutation is performed from the maximum phase to the intermediate phase, the switches S _1a and S _{2a / b} are operated as IGBTs, and the switches S _1b and S _{2b / a} are operated as freewheeling diodes. As shown in FIG. 12B, first, the switch _{S2b / a} is turned on to secure a reflux path. A period in which the element in the freewheeling diode mode is always turned on is defined as a commutation period. Next, switch _{S1a is} turned off and _{S2a / b is} turned on in turn, and finally switch _S1b is turned off to complete commutation.

As is clear from FIG. 12B, since a plurality of AC switches S ₁ , S ₂ , S ₃ are not turned on during the commutation period, a power supply short circuit does not occur. Further, since the current path is always secured, the load end is not opened. Incidentally, as shown in FIG. 12 (a), (b) , when performing the commutation between a maximum phase and the intermediate phase, AC switch S ₃ not subjected to switching is always OFF.
This type of technology is disclosed in, for example, Patent Document 1.

JP 2001-61276 A ([0025] to [0044], FIG. 5 etc.)

  In the prior art described in Patent Document 1, since the PWM pattern is determined in accordance with the magnitude relationship between the two-phase power supply voltages for commutation, it is essential to accurately determine the magnitude relationship between the power supply voltages. However, in the region where the line voltage is near 0 [V] due to the influence of ripple generated by switching, it is difficult to accurately determine the magnitude relation of the power supply voltage. If determined, a power supply short circuit occurs due to a commutation failure.

14, in the commutation period from the AC switch S ₁ to S _2, an operation explanatory diagram of the case where the wrong level decision between the maximum phase and the intermediate phase, Fig. 14 (a) a PWM pulse, FIG. 14 (B) shows an equivalent circuit for one phase (U phase) of the output side of the matrix converter.
PWM pulse generating circuit is always up phase to the AC switch S ₁ is the intermediate phase in the S ₂ is, for determining the minimum phase in the S ₃ is connected, from the maximum phase to the intermediate phase At the time of commutation, the same PWM pulse as that shown in FIG. 12B is output as shown in FIG. For this reason, the switches S _1b and S _{2b / a} are always on during the commutation period.

However, the error magnitude determination between the maximum phase and the intermediate phase, when the AC switch S ₁ is AC switch S ₂ is connected to the intermediate phase is connected to the maximum phase, the connection state as shown in FIG. 14 (b) Become. At this time, since the switches S _1b and S _{2b / a} are always on as shown in FIG. 14A during the commutation period, the maximum and intermediate phases are connected via these switches S _1b and S _{2b / a.} A short-circuit current flows between the two lines as shown by a broken line.
Minimum phase from the intermediate phase, i.e., when performing commutation to S ₃ from the AC switch S _2, Incorrect level decision between the intermediate phase and the minimum phase, the power source short circuit is generated for the same reason.
As a result, a current exceeding the rating may flow to the switching element and cause destruction, and there is a concern that the reliability of the device may be reduced.

  Therefore, the problem to be solved by the present invention is to control a highly reliable and inexpensive AC / AC direct converter that simply realizes a PWM pattern in which a power supply short circuit does not occur even when the magnitude relationship between power supply voltages is misjudged. To provide an apparatus.

In order to solve the above-mentioned problem, the invention described in claim 1 comprises an AC switch capable of controlling a bidirectional current by combining a plurality of unidirectional switches capable of controlling a unidirectional current. In an AC / AC direct converter that directly converts a three-phase AC voltage to a three-phase AC voltage having an arbitrary magnitude and frequency by turning on and off,
A magnitude discrimination means for discriminating the magnitude relationship between the phase voltages of the three-phase AC power supply,
A commutation direction discriminating means for discriminating between the phase of the maximum voltage phase, the intermediate voltage phase, and the minimum voltage phase among the phase voltages;
Means for constantly turning on a unidirectional switch for passing current from the power supply side to the load side in the AC switch connected to the minimum voltage phase;
Upon determining the commutation between a maximum voltage phase and the intermediate voltage phase by the commutation direction identification means, in the commutation period, the power source side in the AC switch connected to the intermediate voltage phase Means for always turning off a unidirectional switch for passing a current to the load side.

The invention described in claim 2 comprises an AC switch capable of controlling a bidirectional current by combining a plurality of unidirectional switches capable of controlling a unidirectional current, and a three-phase alternating current by turning the unidirectional switch on and off. In an AC / AC direct converter that directly converts a voltage into a three-phase AC voltage having an arbitrary magnitude and frequency,
A magnitude discrimination means for discriminating the magnitude relationship between the phase voltages of the three-phase AC power supply ,
A commutation direction discriminating means for discriminating between the phase of the maximum voltage phase, the intermediate voltage phase, and the minimum voltage phase among the phase voltages ;
Region discriminating means for discriminating a period in which the voltage of the maximum voltage phase and the voltage of the intermediate voltage phase are substantially equal;
Current is passed from the power supply side to the load side in the AC switch connected to the minimum voltage phase during the period when the voltage of the maximum voltage phase and the voltage of the intermediate voltage phase are determined to be approximately equal by this region discrimination means. Means to always turn on the unidirectional switch,
In the period, when it is determined the commutation between a maximum voltage phase and the intermediate voltage phase by the commutation direction identification means, in the commutation period, in the AC switch connected to the intermediate voltage phase and means for always turning off the unidirectional switch flowing through the current to the load side from the power source side are those having a.

The invention described in claim 3 comprises an AC switch capable of controlling a bidirectional current by combining a plurality of unidirectional switches capable of controlling a unidirectional current, and a three-phase alternating current by turning the unidirectional switch on and off. In an AC / AC direct converter that directly converts a voltage into a three-phase AC voltage having an arbitrary magnitude and frequency,
A magnitude discrimination means for discriminating the magnitude relationship between the phase voltages of the three-phase AC power supply ,
A commutation direction discriminating means for discriminating between the phase of the maximum voltage phase, the intermediate voltage phase, and the minimum voltage phase among the phase voltages ;
Means for constantly turning on a unidirectional switch for passing current from the load side to the power source side in the AC switch connected to the maximum voltage phase;
Upon determining the commutation between the minimum voltage phase and the intermediate voltage phase by the commutation direction identification means, in the commutation period, from the load side of the AC switch connected to the intermediate voltage phase And a means for always turning off a unidirectional switch for passing a current to the power source side.

The invention described in claim 4 constitutes an AC switch capable of controlling a bidirectional current by combining a plurality of unidirectional switches capable of controlling a unidirectional current, and a three-phase alternating current by turning the unidirectional switch on and off. In an AC / AC direct converter that directly converts a voltage into a three-phase AC voltage having an arbitrary magnitude and frequency,
A magnitude discrimination means for discriminating the magnitude relationship between the phase voltages of the three-phase AC power supply ,
A commutation direction discriminating means for discriminating between the phase of the maximum voltage phase, the intermediate voltage phase, and the minimum voltage phase among the phase voltages ;
Area discriminating means for discriminating a period in which the voltage of the minimum voltage phase and the voltage of the intermediate voltage phase are substantially equal;
Current is passed from the load side to the power supply side in the AC switch connected to the maximum voltage phase during the period in which the voltage of the minimum voltage phase and the voltage of the intermediate voltage phase are determined to be approximately equal by this region discrimination means. Means to always turn on the unidirectional switch,
In the period, when it is determined the commutation between the minimum voltage phase and the intermediate voltage phase by the commutation direction identification means, in the commutation period, in the AC switch connected to the intermediate voltage phase and means for turning off always unidirectional switch flowing through the current source side from the load side are those having a.

  In the present invention, the commutation between the maximum phase, the intermediate phase, and the minimum phase is detected, and further, if necessary, it is detected whether it is a period (region) in which the magnitude relationship of each phase voltage is easily misidentified. In addition, by controlling on / off of a specific switch such as a unidirectional switch in the freewheeling diode mode connected to the intermediate phase, the load end is prevented from being opened at the time of commutation, and the power supply voltage is mistakenly determined. However, a highly reliable control device that does not cause a power supply short circuit can be provided.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 is a functional block diagram showing a first embodiment of the present invention corresponding to claim 1, and corresponds to a PWM pulse generating circuit for one phase on the output side of the matrix converter shown in FIG.

In FIG. 1, the edge detection means 1 as the commutation direction determination means includes on / off command values S ₁ ^* , S ₂ ^* , S ₃ for the AC switches S ₁ , S ₂ , S ₃ shown in FIG. ^* Is input, and by detecting the edge of these command values, it is possible to determine from which phase to which phase. The detection output of the edge detection means 1 is input to the commutation generation means 2, and the commutation generation means 2 performs the six unidirectional switches S _1a , FIG. 11A based on the output of the edge detection means 1. PWM pulses of S _1b , S _{2a / b} , S _{2b / a} , S _3a , S _3b are created and output to the pulse distribution means 3 side. In FIG. 1, the symbols S _1a , S _1b , S _{2a / b} , S _{2b / a} , S _3a , S _3b are also used when referring to PWM pulses.

On the other hand, each phase voltage v _R , v _S , v _T of the three-phase AC power source is input to the magnitude discrimination means 4 and is obtained by discriminating the maximum phase, the intermediate phase, and the minimum phase based on the amplitude of each phase voltage. A magnitude discrimination signal is output to the pulse distribution means 3. In the pulse distribution means 3, the PWM pulses S _1a , S _1b , S _{2a / b} , S _{2b / a} , S _3a , S _3b are unidirectional switches corresponding to one phase on the output side (for example, FIG. 11 ( The AC switches S _RU , S _SU , S _TU in b) are distributed to a total of six unidirectional switches).

Here, the commutation generator 2, a signal PWM pulse unidirectional switch S _3b flowing through the current to the load side from the power supply side of the AC switch S ₃ which is connected to the minimum phase is always 1 and the output _S3b is always on. The intermediate phase freewheeling diode (FWD) mode off means 5A connected to the output side of the edge detection means 1 detects the occurrence of commutation between the maximum phase and the intermediate phase from the output of the edge detection means 1, A signal that becomes 0 in this commutation period is output. Unidirectional this signal wheeling diode mode during commutation between the unidirectional switch (maximum phase and the intermediate phase flowing through the current to the load side from the power supply side of the AC switch S ₂ being connected to an intermediate phase Switch) is input to AND means 6 together with the PWM pulse for S _{2b / a} , and its output becomes the final PWM pulse for unidirectional switch S _{2b / a} .
As a result, when commutation is performed between the maximum phase and the intermediate phase, the unidirectional switch S _{2b / a} that passes current from the power supply side to the load side among the AC switches connected to the intermediate phase is: It is always off during the commutation period. Note that the PWM pulses of the other unidirectional switches S _1a , S _1b , S _{2a / b} , S _3a and the method for producing them are the same as those in the prior art shown in FIG.

2 and 3 show PWM pulses in this embodiment, FIG. 2 shows a case where commutation occurs between the maximum phase and the intermediate phase, and FIG. 3 shows a case where commutation occurs between the intermediate phase and the minimum phase. It is.
2 from (a), the commutation of the _{S 1} is generated from the AC switch _{S 2,} unidirectional switch _{S 2b / a} is turned off immediately. In the prior art, as shown in FIG. 12A, the unidirectional switch _{S2b / a} needs to be turned on until commutation is completed in order to secure a positive load current path.
However, in this first embodiment, since the unidirectional switch _S3b is always on and the path of the positive load current is always secured, the unidirectional switch S2b _{/ a} is turned off simultaneously with the start of commutation. Can also prevent the load end from being opened.

Further, in the region where the maximum phase voltage and the intermediate phase voltage are approximately equal, as in the case where the line voltage is near 0 [V], the magnitude relationship may be erroneously determined. In the prior art, the unidirectional switches S _1b and S _{2b / a} are always on during the commutation period from the AC switch S ₁ to S ₂ as shown in FIG. In this way, a power supply short circuit occurs due to a misjudgment of the magnitude relationship. However, according to the first embodiment, since the commutation period in unidirectional switch S _{2b / a} from the AC switch S ₁ to S ₂ is turned off at all times, the magnitude of the maximum phase voltage and the intermediate phase voltage indetermination Even if it separates, a power supply short circuit does not occur.

On the other hand, if the commutation from the AC switch S ₁ to S ₂ occurs, in the prior art, the commutation at the same time as the start unidirectional switch S _{2b / a,} as shown in FIG. 12 (b) is turned on, first In the embodiment, as shown in FIG. 2B, the unidirectional switch _{S2b / a} is turned on simultaneously with the completion of commutation. Again, is the path of the positive load current by unidirectional switch S _3b, which are on, always is always ensured, since unidirectional switches _{S 1b,} S 2b / _a is never turned on at the same time, the load end open In addition, a power supply short circuit does not occur due to a misjudgment of the magnitude relationship between the maximum phase voltage and the intermediate phase voltage.
As shown in FIG. 3, if the commutation between the AC switch S ₂ and S ₃ occurs, except that the unidirectional switch S _3b is turned on at all times, the prior art PWM shown in FIG. 13 Same as pulse.

As described above, in the first embodiment, the unidirectional switch _S3b is always on. That is, since the turning on when the commutation has occurred even unidirectional switch S _3b in AC switch S ₃ of the minimum phase between the AC switch S ₂ of the maximum phase of the AC switch S ₁ and the intermediate phase This causes a problem that the maximum voltage that can be output decreases.

  The second embodiment of the present invention is for solving the above problem. That is, in the second embodiment, the PWM pulse according to the first embodiment is generated only during a period when the magnitudes of the maximum phase voltage and the intermediate phase voltage are substantially equal and there is a high possibility that the magnitude relationship is erroneously discriminated. .

FIG. 4 is a functional block diagram showing a second embodiment of the present invention corresponding to the second aspect. In this embodiment, compared to the first embodiment of FIG. 1, the region discriminating means 7A to which the phase voltages v _R , v _S , and v _T are inputted, and the region discriminating signal that is the output thereof are applied to the unidirectional switch S _3b . The logical sum means 8 input together with the PWM signal is added, and the output of the logical sum means 8 is inputted to the pulse distribution means 3 as the final PWM pulse for the unidirectional switch _S3b .

FIG. 5 is a diagram for explaining the function of the region discriminating means 7A. The area discriminating means 7A detects a period (area A) in which the maximum phase voltage and the intermediate phase voltage are substantially equal based on the phase voltages v _R , v _S , v _T of the three-phase AC power supply, and the area shown in FIG. An area determination signal which is 1 in A is generated. Since the PWM pulse of the unidirectional switch S _3b is the logical sum of the output of the commutation generating means 2 and the region discrimination signal, the PWM pulse S _3b is always 1 in the region A, and the circuit configuration is substantially the same as in FIG. At the same time, in the region C other than the region A in FIG. 5, the PWM pulse S _3b is equal to the output of the commutation generating means 2 and is the same as in the prior art.
Further, since the output signal of the edge detection means 1 and the region discrimination signal are also input to the intermediate phase FWD mode off means 5B in FIG. 4, the intermediate phase FWD mode off means 5B has an intermediate phase between the maximum phase and the intermediate phase. A signal that is 0 is output when the commutation period is in progress and the current time is the region A. Therefore, in the region A, the same PWM pulse as that in the first embodiment is applied to each unidirectional switch in the region C, and the same PWM pulse as that in the conventional technique is applied to each unidirectional switch.

Since the region A has a short period, even if the unidirectional switch _S3b in the minimum voltage phase is always turned on only during this period, the output voltage is not greatly affected. In the region C, the PWM pulse is the same as that of the prior art, but since there is little possibility of misjudging the magnitude relationship between the maximum phase voltage and the intermediate phase voltage, it is possible to prevent a power supply short circuit due to a magnitude relationship misjudgment. . Therefore, the same effect as that of the first embodiment can be obtained in the second embodiment.

FIG. 6 is a functional block diagram showing a third embodiment of the present invention corresponding to the third aspect. In this embodiment, the PWM pulse of the unidirectional switch S _{2a / b} in which the output of the intermediate phase FWD mode off means 5C flows current from the load side to the power source side of the AC switch S ₂ connected to the intermediate phase. At the same time, it is input to the logical product means 6, and its output is input to the pulse distribution means 3 as the final PWM pulse of the unidirectional switch _{S2a / b} .

Since the basic method for generating the PWM pulse in this embodiment is the same as that in the first embodiment, the following description will be focused on the differences from the first embodiment.
In the present embodiment, the PWM pulse of the unidirectional switch S _{1b that} allows current to flow from the load side to the power source side of the AC switch S ₁ connected to the maximum phase is a signal that is always 1 from the commutation generating means 2. Is always turned on. Further, the intermediate phase FWD mode off means 5C detects the occurrence of commutation between the intermediate phase and the minimum phase from the output of the edge detection means 1, and outputs a signal that becomes 0 during this commutation period. As a result, when performing commutation between the intermediate phase and the minimum phase, unidirectional switch (mesophase flowing through the current to the power supply side from the load side of the AC switch S ₂ being connected to an intermediate phase The unidirectional switch in the freewheeling diode mode at the time of commutation with the minimum phase) _{S2a / b} is always off during the commutation period.

7 and 8 show PWM pulses in this embodiment. FIG. 7 shows commutation between the intermediate phase and the minimum phase, and FIG. 8 shows commutation between the maximum phase and the intermediate phase. Is the case.
7 (a), the commutation to _{S 3} is generated from the AC switch _{S 2,} unidirectional switches _{S 2a / b} is turned off immediately. In the prior art, as shown in FIG. 13A, the unidirectional switch _{S2a / b} needs to be turned on until the commutation is completed in order to secure a negative load current path.
However, in this embodiment, as shown in FIG. 7A, the unidirectional switch _S1b is always on and the path of the negative load current is always secured, so that the unidirectional switch S2a _{/ b} is commutated. Even if it is turned off simultaneously with the start, it is possible to prevent the load end from being opened.

Further, in the prior art, the erroneous determines the size relationship between the intermediate phase voltage and the minimum phase voltage, FIG. 13 (a) in the AC switch S during commutation period to the S ₃ from _2-way switch S _3b, S _{Since 2a / b} is always on, a power supply short circuit occurs.
However, according to this embodiment, since the commutation period in unidirectional switches S _{2a / b} from AC switch S ₂ to S ₃ as shown in FIGS. 7 (a) is always off, if the intermediate phase voltage Even if the magnitude relationship between the voltage and the minimum phase voltage is misjudged, a power supply short circuit does not occur.

On the other hand, if the commutation to S ₂ from the AC switch S ₃ is generated, in the prior art, although unidirectional switches S _{2a / b} simultaneously with commutation begins as shown in FIG. 13 (b) is turned on, this embodiment In the embodiment, as shown in FIG. 7B, the unidirectional switch _{S2a / b} is turned on simultaneously with the completion of the commutation. Again, is the path of the negative load current by unidirectional switch S _1b are constantly on is always ensured, since unidirectional switches _{S 3b,} S 2b / _a is never turned on at the same time, the load end open In addition, a power supply short circuit due to a misjudgment of the magnitude relationship between the intermediate phase voltage and the minimum phase voltage does not occur.
As shown in FIG. 8, if the commutation between the AC switch S ₁ and S ₂ is generated, except that the unidirectional switch S _1b is turned on at all times, the prior art PWM shown in FIG. 12 Same as pulse.

In the third embodiment described above, the unidirectional switch _S1b is always on, so that the generated output voltage error may increase.
Therefore, in the fourth embodiment, the output voltage error is suppressed.

FIG. 9 is a functional block diagram showing a fourth embodiment of the present invention corresponding to the fourth aspect.
This embodiment, an area discriminating signal from the region judging means 7B to generate a PWM pulse addition unidirectional switch S _1b to the logical sum unit 8, the output of the intermediate phase FWD mode off means 5D to the logical product means 6 In addition, the PWM pulse of the unidirectional switch _{S2a / b} is generated.

The region discriminating means 7B has a function of discriminating a region where the magnitudes of the intermediate phase voltage and the minimum phase voltage are substantially equal from the phase voltages v _R , v _S , and v _T. FIG. 10 is an explanatory diagram of this function. It is.
That is, the region discriminating means 7B outputs a discrimination signal that becomes 1 in the region B of FIG. 10 in which the magnitudes of the intermediate phase voltage and the minimum phase voltage are substantially equal. As a result, in the region B, the unidirectional switch _S1b is always on, but in the region D, it is the same as the conventional PWM pulse.

The intermediate phase FWD mode off means 5D detects the commutation between the intermediate phase and the minimum phase from the output of the edge detection means 1, and the magnitude relationship between the intermediate phase voltage and the minimum phase voltage is the commutation period. When it corresponds to the region B, a signal that becomes 0 is output. Therefore, the unidirectional switch S _{2a / b} is always turned off when commutation is performed between the intermediate phase and the minimum phase in the region B.
From the above, it can be seen that the PWM pulse according to the third embodiment is applied to each unidirectional switch in the region B of FIG.

In the region D, since there is no difference in magnitude between the intermediate phase voltage and the minimum phase voltage, no problem occurs even if the same PWM pulse as in the prior art is used. Also, the PWM pulse that always turns on the unidirectional switch _S1b according to the third embodiment is used for a short period in which the intermediate phase voltage and the minimum phase voltage are substantially equal, and therefore the influence on the output voltage is minimized. Thus, the voltage error can be reduced.

  In the above description, a power supply short circuit due to a magnitude error determination between the maximum phase voltage and the intermediate phase voltage according to the second embodiment, and a power supply short circuit due to a size error determination between the intermediate phase voltage and the minimum phase voltage according to the fourth embodiment, respectively. Can be prevented. Therefore, when these embodiments are used in combination, it is possible to perform a commutation operation in which the load end opening and the power supply short circuit do not occur under any conditions, and in particular, a power supply short circuit occurs even when the power supply voltage magnitude determination is wrong. No commutation operation can be realized.

  In addition, since the area discriminating means 7A, 7B and the intermediate phase FWD mode off means 5B, 5D in the second and fourth embodiments have many functionally common parts, the area is used when these embodiments are used together. The discriminating means 7A, 7B can be integrated into a single means, and the intermediate phase FWD mode off means 5B, 5D can be integrated into a single means, and there is no problem such as a complicated circuit.

It is a functional block diagram which shows 1st Embodiment of this invention. In 1st Embodiment, it is explanatory drawing of the PWM pulse in the case of performing commutation between the largest phase and an intermediate | middle phase. In 1st Embodiment, it is explanatory drawing of the PWM pulse in the case of performing commutation between an intermediate | middle phase and the minimum phase. It is a functional block diagram which shows 2nd Embodiment of this invention. It is a figure explaining the function of the area | region discrimination | determination means in FIG. It is a functional block diagram which shows 3rd Embodiment of this invention. In 3rd Embodiment, it is explanatory drawing of the PWM pulse in the case of performing commutation between an intermediate | middle phase and the minimum phase. In 3rd Embodiment, it is explanatory drawing of the PWM pulse in the case of performing commutation between the largest phase-intermediate phase. It is a functional block diagram which shows 4th Embodiment of this invention. It is a figure explaining the function of the area | region discrimination | determination means in FIG. It is a connection block diagram of the alternating current switch of a matrix converter. It is explanatory drawing of the PWM pulse in the case of performing commutation between an intermediate | middle phase and the largest phase. It is explanatory drawing of the PWM pulse in the case of performing commutation between an intermediate | middle phase and the minimum phase. It is operation | movement explanatory drawing at the time of the magnitude discrimination between a maximum phase voltage and an intermediate phase voltage having been mistaken.

Explanation of symbols

1: Edge detection means 2: Commutation generation means 3: Pulse generation means 4: Size determination means 5A, 5B, 5C, 5D: Intermediate phase freewheeling diode (FWD) mode-off means 6: Logical product means 7A, 7B: Area determination It means 8: logical OR means _{S 1, S 2, S 3} : AC switch _{S 1a, S 1b, S 2a} / b, S 2b / a, S 3a, S 3b: unidirectional switch

Claims (4)

Combining multiple unidirectional switches that can control a unidirectional current to form an AC switch that can control a bidirectional current. By turning the unidirectional switch on and off, the three-phase AC voltage can be set to any magnitude and frequency In an AC / AC direct converter that converts directly into a three-phase AC voltage,
A magnitude discrimination means for discriminating the magnitude relationship between the phase voltages of the three-phase AC power supply,
A commutation direction discriminating means for discriminating between the phase of the maximum voltage phase, the intermediate voltage phase, and the minimum voltage phase among the phase voltages;
Means for constantly turning on a unidirectional switch for passing current from the power supply side to the load side in the AC switch connected to the minimum voltage phase;
Upon determining the commutation between a maximum voltage phase and the intermediate voltage phase by the commutation direction identification means, in the commutation period, the power source side in the AC switch connected to the intermediate voltage phase Means for always turning off a unidirectional switch for passing current to the load side;
An AC / AC direct converter control device comprising: Combining multiple unidirectional switches that can control a unidirectional current to form an AC switch that can control a bidirectional current. By turning the unidirectional switch on and off, the three-phase AC voltage can be set to any magnitude and frequency In an AC / AC direct converter that converts directly into a three-phase AC voltage,
A magnitude discrimination means for discriminating the magnitude relationship between the phase voltages of the three-phase AC power supply,
A commutation direction discriminating means for discriminating between the phase of the maximum voltage phase, the intermediate voltage phase, and the minimum voltage phase among the phase voltages;
Region discriminating means for discriminating a period in which the voltage of the maximum voltage phase and the voltage of the intermediate voltage phase are substantially equal;
Current is passed from the power supply side to the load side in the AC switch connected to the minimum voltage phase during the period when the voltage of the maximum voltage phase and the voltage of the intermediate voltage phase are determined to be approximately equal by this region discrimination means. Means to always turn on the unidirectional switch,
In the period, when it is determined the commutation between a maximum voltage phase and the intermediate voltage phase by the commutation direction identification means, in the commutation period, in the AC switch connected to the intermediate voltage phase and means for always turning off the unidirectional switch flowing through the current to the load side from the electrical side,
An AC / AC direct converter control device comprising: Combining multiple unidirectional switches that can control a unidirectional current to form an AC switch that can control a bidirectional current. By turning the unidirectional switch on and off, the three-phase AC voltage can be set to any magnitude and frequency In an AC / AC direct converter that converts directly into a three-phase AC voltage,
A magnitude discrimination means for discriminating the magnitude relationship between the phase voltages of the three-phase AC power supply,
A commutation direction discriminating means for discriminating between the phase of the maximum voltage phase, the intermediate voltage phase, and the minimum voltage phase among the phase voltages;
Means for constantly turning on a unidirectional switch for passing current from the load side to the power source side in the AC switch connected to the maximum voltage phase;
Upon determining the commutation between the minimum voltage phase and the intermediate voltage phase by the commutation direction identification means, in the commutation period, from the load side of the AC switch connected to the intermediate voltage phase Means for always turning off a unidirectional switch for passing current to the power supply side;
An AC / AC direct converter control device comprising: Combining multiple unidirectional switches that can control a unidirectional current to form an AC switch that can control a bidirectional current. By turning the unidirectional switch on and off, the three-phase AC voltage can be set to any magnitude and frequency In an AC / AC direct converter that converts directly into a three-phase AC voltage,
A magnitude discrimination means for discriminating the magnitude relationship between the phase voltages of the three-phase AC power supply,
A commutation direction discriminating means for discriminating between the phase of the maximum voltage phase, the intermediate voltage phase, and the minimum voltage phase among the phase voltages;
Area discriminating means for discriminating a period in which the voltage of the minimum voltage phase and the voltage of the intermediate voltage phase are substantially equal;
Current is passed from the load side to the power supply side in the AC switch connected to the maximum voltage phase during the period in which the voltage of the minimum voltage phase and the voltage of the intermediate voltage phase are determined to be approximately equal by this region discrimination means. Means to always turn on the unidirectional switch,
In the period, when it is determined the commutation between the minimum voltage phase and the intermediate voltage phase by the commutation direction identification means, in the commutation period, in the AC switch connected to the intermediate voltage phase and means for always turning off the unidirectional switch flowing through the current source side from the load side,
An AC / AC direct converter control device comprising:

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