JP6860144B2 - Power converter control device - Google Patents

Description

The present invention relates to a control device for a power converter, and more particularly to a control device for a power converter which is a bidirectional isolated AC / DC converter to which a matrix converter is applied.

In recent years, the use of DC devices such as electric vehicles and household storage batteries has begun to spread. In this type of DC equipment, a bidirectional isolated AC / DC converter for converting a three-phase alternating current supplied from a system power supply into a direct current is used.

The conventional bidirectional isolated AC / DC converter is a first AC / DC converter that converts a three-phase alternating current into a direct current, and a DC / AC that converts a direct current output from the first AC / DC converter into a high-frequency alternating current. It is composed of a converter, a high-frequency transformer that insulates the high-frequency alternating current output from the DC / AC converter, and a second AC / DC converter that converts the high-frequency alternating current that appears on the secondary side of the high-frequency alternating current into DC. Therefore, since it is necessary to perform power conversion three times, there is a problem that it is difficult to obtain high conversion efficiency. Further, since a large electrolytic capacitor is required between the first AC / DC converter and the DC / AC converter, there is also a problem that the apparatus becomes large in size and has a short life.

On the other hand, recently, it has been studied to apply the matrix converter disclosed in Non-Patent Document 1 to a bidirectional isolated AC / DC converter. If a matrix converter is used, a three-phase alternating current can be converted into a high-frequency alternating current without using a direct current, and a large electrolytic capacitor is not required, so that the above-mentioned problems of the bidirectional isolated AC / DC converter can be solved.

Non-Patent Document 2 discloses an example of an isolated AC / DC converter to which a matrix converter is applied. According to this example, the operation timing of each switch constituting the matrix converter is determined by comparing the sawtooth wave oscillating at a predetermined cycle with the waveform of the three-phase alternating current.

Min Chengqing, 3 outsiders, "Study on Improvement Method of Input / Output Current Waveform of Matrix Converter", IEEJ Transactions D, Institute of Electrical Engineers of Japan, 2003, Vol. 123, No. 11, p. 1276-1284 Kazuma Suzuki, 3 outsiders, "Insulated AC / DC converter with soft switching", Institute of Electrical Engineers of Japan D, Institute of Electrical Engineers of Japan, 2016, Vol. 136, No. 8, p. 540-548

However, when the operation timing of each switch constituting the matrix converter is determined by the method described in Non-Patent Document 2, the operation timing is not always optimal, and as a result, the harmonics of the AC input current increase. was there.

Therefore, one of the objects of the present invention is to provide a control device of a power conversion device capable of reducing harmonics of an AC input current in an isolated AC / DC converter to which a matrix converter is applied.

The control device of the power conversion device according to the present invention is connected to a transformer having first and second coils magnetically coupled to each other, one end to a fifth node constituting one end of the load, and the other end to the second coil. A first one-way switch element connected to a third node constituting one end of a coil, one end connected to a sixth node constituting the other end of the load, and the other end connected to the third node. Second unidirectional switch element, one end connected to the fifth node and the other end connected to a fourth node constituting the other end of the second coil. An AC / DC converter having a fourth one-way switch element, one end of which is connected to the sixth node and the other end of which is connected to the fourth node, and the first phase of three-phase AC at one end. A first bidirectional switch element connected to a seventh node corresponding to the above, the other end connected to one end of the first coil via a reactor, and one end connected to the three-phase. A second bidirectional switch element connected to an eighth node corresponding to the second phase of AC, the other end connected to the first node, and one end corresponding to the third phase of the three-phase AC. A third bidirectional switch element connected to a node of 9, the other end connected to the first node, one end connected to the seventh node, and the other end the other end of the first coil. A fourth bidirectional switch element connected to a second node, a fifth bidirectional switch element having one end connected to the eighth node and the other end connected to the second node, and A control device for a power conversion device having a matrix converter having a sixth bidirectional switch element, one end of which is connected to the ninth node and the other end of which is connected to the second node. Indicates the timing for changing the state of each of the first to fourth one-way switch elements and the first to sixth bidirectional switch elements based on the input reception step for receiving the input of the value and the power command value. A calculation step for calculating the duty ratio and a control step for controlling the states of the first to fourth one-way switch elements and the first to sixth bidirectional switch elements based on the duty ratio are executed. It is characterized by that.

In the control device, the control step is configured to perform a repetitive operation with the first to sixth periods as one cycle, and the duty ratio is the time length of the first to sixth periods. It is also good.

In the control device, the first to third AC voltages are provided for each of the first to twelfth spaces determined according to the phases of the first to third AC voltages corresponding to the first to third phases, respectively. The largest of the above is the maximum phase voltage, the middle of the first to third AC voltages is the intermediate phase voltage, and the smallest of the first to third AC voltages is the minimum. The phase voltage is defined as the intermediate phase voltage among the first to third currents flowing through the seventh to ninth nodes, respectively, and the intermediate phase voltage is defined as the intermediate phase voltage when the intermediate phase current is larger than zero. Input voltage equal to the voltage obtained by subtracting the minimum phase voltage from the intermediate phase voltage, and equal to the voltage obtained by subtracting the intermediate phase voltage from the maximum phase voltage when the intermediate phase current is smaller than zero. Then, in the control step, in the first period, the first voltage, which is the voltage of the first node with respect to the voltage of the second node, subtracts the minimum phase voltage from the maximum phase voltage. The state of the first to sixth bidirectional switch elements is controlled so that the voltage becomes the same, and the second voltage, which is the voltage of the fourth node with respect to the voltage of the third node, becomes a negative value. The state of the first to fourth one-way switch elements is controlled so as to be such that, in the second period, the first voltage is a voltage obtained by subtracting the minimum phase voltage from the maximum phase voltage. The state of the first to sixth bidirectional switch elements is controlled so that the state of the first to sixth bidirectional switch elements is controlled, and the state of the first to fourth one-way switch elements is controlled so that the second voltage becomes a positive value. In the third period, the state of the first to sixth bidirectional switch elements is controlled so that the first voltage becomes the input voltage, and the second voltage becomes a positive value. The state of the first to fourth one-way switch elements is controlled so that the first voltage becomes a voltage obtained by subtracting the maximum phase voltage from the minimum phase voltage in the fourth period. The state of the first to sixth bidirectional switch elements is controlled, and the state of the first to fourth one-way switch elements is controlled so that the second voltage becomes a positive value. In the period 5, the state of the first to sixth bidirectional switch elements is controlled so that the first voltage becomes a voltage obtained by subtracting the maximum phase voltage from the minimum phase voltage, and the first voltage is controlled. The state of the first to fourth one-way switch elements is controlled so that the voltage of 2 becomes a negative value. In the sixth period, the state of the first to sixth bidirectional switch elements is controlled so that the first voltage is the reciprocal of the input voltage, and the second voltage is negative. The state of the first to fourth unidirectional switch elements may be controlled so as to be a value.

In the control device, the one corresponding to the maximum phase voltage among the first to third currents is defined as the maximum phase current, and when the intermediate phase current is larger than zero, it is equal to the maximum phase current and the intermediate. When the phase current is smaller than zero, the input current is a current equal to the sum of the maximum phase current and the intermediate phase current. In the calculation step, the maximum phase current and the intermediate phase are based on the power command value. A step of calculating a command value for each of the currents, a step of calculating a command value of the input current based on the calculated command values of the maximum phase current and the intermediate phase current, and a command value of the calculated input current. And the step of deriving the first duty ratio such that is equal to a predetermined first function which is a function of the first duty ratio indicating the time length of each of the first and fourth periods, and the first step. Based on the duty ratio of 1, the second duty ratio indicating the time length of each of the second and fifth periods and the third duty ratio indicating the time length of each of the third and sixth periods are obtained. It may include a step to calculate.

In the control device, the other end of each of the first to third bidirectional switch elements is connected to the first node via a common inductance, and the first function is the first duty ratio. D ₀ , the inverse of the total time lengths of the first to sixth periods is f, the inductance of the reactor is L, the voltage of the fifth node is V _dc with respect to the voltage of the sixth node, and the maximum. show phase voltage _{e max,} the minimum phase voltage _{e min,} the input voltage _{e m,} when the intermediate phase current and _{i mid,} the variable _{D 1} and formula shown in equation (5) below (6) using variable a, B, and C that may be be represented by _i m _{(D 0)} represented by formula (4) below.

In the control device, the control step transitions between a predetermined positive voltage and a predetermined negative voltage at a cycle in which the second voltage corresponds to half of the total time length of the first to sixth periods. The state of the first to fourth unidirectional switch elements may be controlled so as to obtain a rectangular wave signal.

According to the present invention, the duty ratio indicating the timing of changing the state of each of the first to fourth unidirectional switch elements and the first to sixth bidirectional switch elements is calculated and calculated based on the power command value. Since the states of the first to fourth one-way switch elements and the first to sixth bidirectional switch elements are controlled based on the duty ratio, the states of each switch element should be controlled at the optimum timing. Becomes possible. Therefore, it is possible to reduce the harmonics of the AC input current by the power converter which is an isolated AC / DC converter to which the matrix converter is applied.

It is a figure which shows the structure of the electric power conversion apparatus 1 and its control apparatus 4 by a preferable embodiment of this invention. (A) is a diagram showing a first example of a detailed configuration of the switching element S _xy, (b) is a diagram showing a second example of a detailed configuration of the switching element S _xy. Voltage _e u shown in FIG. _{1, e v, e w,} v 1, v 2 and the current _{i eu, i ev, i ew} , i L, the signal waveform diagram showing a simulation result of power running of the waveform of _{i u} is there. It is an enlarged view of the region A shown in FIG. (A) is _{a signal waveform diagram schematically showing the waveforms of the voltages v 1} , v ₂ and the current i _{L at} the time of power running, and (b) is the signal waveform diagram at the time of regeneration _{of the voltages v 1} , v ₂ and the current i _L. It is a signal waveform diagram which shows the waveform schematically. It is a flow chart which shows the switching control processing performed by the control device 4 shown in FIG. It is a flow chart which shows the detail of the duty ratio calculation process shown in FIG. (A), the voltage _e u shown in FIG. _1, v 1, _{v 2} and the current _i eu, a signal waveform diagram showing experimental results of the power running of the waveform of _{i L,} (b) is 1 voltage indicated _{e u, v 1,} v ₂ and the current _i eu, a signal waveform diagram showing experimental results of the waveform at the time of regeneration of the _{i L,} (c) is an enlarged view of a region B shown in (a) (D) is an enlarged view of the region C shown in (b). (E _max- e _mid )> (e _mid- e _min ), e _mid <0, or a signal schematically showing the waveforms of the voltages v ₁ , v ₂ and the current i _{L during power running when i mid <0.} It is a waveform diagram. (A) ~ (c) are diagrams showing the outline of the function _i m _{(D 0).}

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a diagram showing a configuration of a power conversion device 1 and a control device 4 thereof according to the present embodiment.

As shown in FIG. 1, the power conversion device 1 according to the present embodiment includes a matrix converter 10, a transformer 20, and an AC / DC converter 30. These are connected between the system power supply 2 and the load 3 in the order of the matrix converter 10, the transformer 20, and the AC / DC converter 30. In the following, as illustrated, seventh node n ₇ 3 one end of the matrix converter 10 connected to the system power supply 2, _{respectively,} eighth node n _8, called nodes n ₉ ninth, trans 20 the two ends of the matrix converter 10 connected to a respective one of the nodes n _1, referred to as a second node n _2, the two ends of each third AC / DC converter 30 connected to the transformer 20 node _{n 3,} referred to as a fourth node _{n 4,} the fifth node _{n 5} 2 two ends of the AC / DC converter 30 connected to the load 3, respectively, referred to as node _{n 6} of the sixth. Further, the voltage of the first node n _{1 with respect to the voltage of the second} node n 2 is referred to as a voltage v ₁ (first voltage), and the voltage of the fourth node n ₄ with _{respect to the voltage of the third node n 3 is referred to as a voltage v 1 (first voltage).} It is called voltage v ₂ (second voltage).

The transformer 20 is configured to have two coils 20a and 20b (first and second coils) that are magnetically coupled to each other. One end of the coil 20a is connected to a matrix converter 10 in the first node n ₁ through the reactor L, the other end of the coil 20a is connected to a matrix converter 10 in the second node n _2. One end of the coil 20b is connected to the AC / DC converter 30 at a third node _{n 3,} the other end of the coil 20b is connected to the AC / DC converter 30 in the fourth node _{n 4.}

The AC / DC converter 30 is a power conversion device connected between the coil 20b and the load 3. The load 3 is, for example, a power converter for driving a motor of a hybrid car, and supplies power to the power converter 1 when it is operated by DC power supplied from the power converter 1 (power running). There is a case (regeneration). As will be described in detail later, the control device 4 performs different operations in the case of power running and the case of regeneration. One end of the load 3 is connected to the AC / DC converter 30 at node _{n 5} of the fifth, the other end of the load 3 is connected to the AC / DC converter 30 at node _{n 6} of the sixth. Further, the voltage of the fifth node n _{5 with respect to the voltage of the sixth} node n 6 is referred to as a voltage V _dc.

The AC / DC converter 30 has a switch element S ₁ (first one-way switch element) having one end _{connected to the fifth node n 5} and the other end connected to the third node n _{3, and one end to the first node.} A switch element S ₂ (second one-way switch element) connected to the node n ₆ of 6 and the other end connected to the third node n _{3 , and one end connected to the fifth node n 5} and others. a switching element S ₃ which end is connected to the fourth node n _{4 (third} unidirectional switching elements), one end connected to the node n ₆ of the sixth and the other end connected to the fourth node n ₄ It has a switch element S ₄ (fourth one-way switch element) and a capacitor C1 having _{one end connected to the fifth node n 5} and the other end connected to the sixth node n _6. Will be done.

Each switching element _S 1 to S ₄ is a uni-directional switch comprising for example only one semiconductor element such as a MOSFET (Metal-Oxide-Semiconductor Field -Effect Transistor) or IGBT (Insulated Gate Bipolar Transistor), shown in FIG. 1 It is configured to include a diode as described above. Switching element S ₁ is incorporated into a circuit as the anode of the diode is connected to the third node n _3, switching element S ₂ is the circuit as the cathode of the diode is connected to the third node n ₃ incorporated in the switch element S ₃ is incorporated in the circuit as the anode of the diode is connected to the fourth node n _4, switching element S _4, the cathode of the diode is connected to the fourth node n ₄ It is incorporated into the circuit so as to.

_{Control signals C 1 to} C ₄ are supplied from the control device 4 to the control electrodes of the semiconductor elements constituting the switch elements S _{1 to} S _{4, respectively.} The control signals C _{1 to} C ₄ are signals that take either a high value or a low value, respectively. The control device 4 individually controls the on / off states _{of the switch elements S 1 to} S ₄ by individually controlling the values of the _{control signals C 1 to} C _4.

The matrix converter 10 is a power conversion device connected between the system power supply 2 and the coil 20a. System power supply 2 is a three-phase AC power supply for generating an AC voltage e _u, e _v, e _w represented by a sinusoidal signal with shifted 2 [pi / 3 by phases, for example, a commercial power supply. As shown in FIG. 1, connected to a matrix converter 10 in the u-phase output end of the system power source 2 corresponding to the AC voltage e _u corresponding to (first phase) _(first AC voltage) node n ₇ of the seventh is, v-phase output end of the system power source 2 corresponding to the AC voltage e _v corresponding to the (second phase) _(second AC voltage) is connected to the matrix converter 10 at node n ₈ of the 8, w phase ( The output terminal of the system power supply 2 corresponding to the AC voltage _ew (third AC voltage) corresponding to the third phase) is connected to the matrix converter 10 at _{the ninth node n 9.} Hereinafter, the seventh to ninth node _n 7 ~n ₉ a current flowing each current _{i eu} (first current), the current _{i ev} (second current), the current _{i ew} (third current) Refer to.

Matrix converter 10 has one end connected to the node n ₇ of the seventh and the other end with the switching element S _up connected to the first node n _{1 (first} bidirectional switch element), one end of the eighth A switch element S _bp (second bidirectional switch element) connected to node n ₈ and the other end connected to the first node n _{1 and one end connected to the ninth node n 9} and the other end. A switch element _Swp (third bidirectional switch element) connected to the first node n _{1 and one end connected to the seventh node n 7} and the other end connected to the second node n ₂ . Switch element _Sun (fourth bidirectional switch element) and switch element S _vn (fifth bidirectional _{) with one end connected to the eighth node n 8} and the other end connected to the second node n _2. A switch element), a switch element _{Swn (sixth bidirectional switch element) having one end connected to the ninth node n 9} and the other end connected to the second node n ₂ , an AC reactor Lf, and the like. It is configured to have an input capacitor Cf.

The AC reactor Lf includes _{an inductor inserted between the seventh node n 7 and the tenth node n 10} which is a connection point between the switch elements _Up and _Sun , and the eighth node n ₈ and the switch element S. _{An inductor inserted between the eleventh node n 11} which is the connection point of _vp and S _{vn , and the twelfth node n 12} which is the connection point between the ninth node n ₉ and the switch elements _Swp and _Swn. It is composed of an inductor inserted between and. The input capacitor Cf is composed of three capacitors connected to each other by a delta connection or star connection, the three connecting points are connected to the node n ₁₀ ~n ₁₂ of the 10 to 12 respectively.

Switching element _{S up, S vp, S wp} , S un, S vn, S wn are respectively the bidirectional switch composed of two semiconductor elements connected in series. Hereinafter, while showing two specific examples, switching element _{S up, S vp, S wp} , S un, S vn, specific structure of _{S wn} be described.

FIG. 2A is a diagram showing a first example of a detailed configuration of the switch element S _xy (x is any of u, v, w, and y is any of p, n). .. In this example, the IGBT is used as the semiconductor element constituting the _{switch element Sxy.} As shown in the figure, the _{two IGBTs constituting the switch element Sxy} are incorporated in the circuit in such a direction that the anodes of the respective diodes are connected to each other.

_{A control signal C xy} is supplied from the control device 4 to the control electrodes of the two IGBTs. This control signal C _xy is composed of two types of signals, and the control device 4 shows the switch element S _xy in a state in which a current flows in the illustrated D1 direction by individually controlling these values. It is defined as one of four states: a state in which a current flows in the D2 direction (direction opposite to the D1 direction), a state in which a current flows in both the D1 direction and the D2 direction, and a state in which no current flows. In the following description, the state in which the current flows in the D1 direction is referred to as "on in the D1 direction", the state in which the current flows in the D2 direction is referred to as "on in the D2 direction", and the current flows in both the D1 direction and the D2 direction. The state is referred to as "both D1D2 on". Then, "on in the D1 direction", "on in the D2 direction", and "both D1D2 on" are collectively referred to as "on", and a state in which no current flows is referred to as "off".

FIG. 2B is a diagram showing a second example of a detailed configuration of _{the switch element Sxy.} In this example, a MOSFET is used as a semiconductor element constituting the _{switch element Sxy.} As shown in the figure, the _{two MOSFETs constituting the switch element Sxy} are incorporated in the circuit in the direction in which the anodes of the respective diodes are connected.

_{Also in this example, a control signal C xy} composed of two types of signals is supplied from the control device 4 to the control electrodes of the two MOSFETs. The control device 4 controls the values of these two types of signals individually to turn the switch element _Sxy into an on state (on in the D1 direction and on in the D2 direction) as in the example of FIG. 2A. , And D1D2 both are on (including each state) and off.

Figure 3 is a signal waveform diagram showing the voltage _{e u, e v, e w} , v 1, v 2 and the current _{i eu, i ev, i ew} , i L, the simulation result of power running of the waveform of _{i u} .. In the figure, voltage e _u, e _v, shows one period of the three-phase AC represented by e _w. Further, FIG. 4 is an enlarged view of the region A shown in FIG.

One cycle of the three-phase alternating current, voltage _{e u,} e v, depending on the phase of the _{e w,} can be divided into twelve space I-XII (first through twelfth space) as shown in FIG. 3 .. Specifically, the space I in which the phase of the voltage e _u is 0 or more and less than π / 6, the space II in which the phase is π / 6 or more and less than π / 3, and the space III and π / in which the phase is π / 3 or more and less than π / 2. Space IV that is 2 or more and less than 2π / 3, space V that is 2π / 3 or more and less than 5π / 6, space VI that is 5π / 6 or more and less than π, space VII that is π or more and less than 7π / 6, 7π / 6 or more Space VIII that is less than 4π / 3, space IX that is 4π / 3 or more and less than 3π / 2, space X that is 3π / 2 or more and less than 5π / 3, space XI that is 5π / 3 or more and less than 11π / 6, 11π / It can be divided into space XII which is 6 or more and less than 2π. As shown in FIG. 3, the region A shown in FIG. 4 is a region in the space IV.

Operation of the control device 4 in each space I~XII the voltage e _u, e _v, except that the switching element to be controlled is switched in accordance with the magnitude of e _w, is basically the same. Therefore, in the following, the case of common explanation in the space I-XII, voltage _{e u,} e v, voltage _{e w} in descending order within each space _{e max} (maximum phase voltage), the voltage _{e mid} (intermediate phase It shall be expressed as voltage) and voltage e _{min (minimum phase voltage).} The current _{i eu,} i _ev, current _{i ew} on descending order within each space _{i max} (maximum phase current), the current _{i mid} (intermediate phase current), and be referred to as current _{i min.} Furthermore, by defining a voltage e _{m (input} voltage) and current i _{m (input} current) as shown in the following equation (1) (2), it will be used for description. It should be noted that the equations (1) and (2) are for power running, and the inequality sign in parentheses is reversed at the time of regeneration.

FIG. 5 (a) is _{a signal waveform diagram schematically showing the waveforms of the voltages v 1} , v ₂ and the current i _L during power running, and FIG. 5 (b) shows the voltages v ₁ , v ₂ and the current i _L. It is a signal waveform diagram which shows typically the waveform at the time of regeneration of. Hereinafter, with reference to these drawings, the switch element _S up by the control unit _{4, S vp, S wp,} S un, S vn, S wn, the control of the state of S 1 to S ₄ will be described.

As shown in FIG. 5A, the power running control device 4 repeatedly operates the frequency f having _{six periods a 1 to} a 6 having a total time length of 1 / f as one cycle. Hereinafter, the operation of the control device 4 in each period will be specifically described.

In the period _{a 1,} the control device 4, the switching element _S up to the voltage _{v 1} becomes _{e max -e min, S vp,} S wp, S un, S vn, to control the status of the _{S wn,} voltage v ₂ controls the state of the switch element _S 1 to S ₄ so that the _{-V dc} (negative value). For example, in the case of the space IV shown in FIG. 3, since e _max = e _u and e _min = e _w , the control device 4 sets the switch element _Sup , _{so that the voltage v 1} becomes e _u −e _{w. Turn} on Switch. Further, the control unit 4, turns on the switching element _S 1, _{S 4} so that the voltage _{v 2} becomes _{-V dc,} and turns off the other switching elements.

In the period _{a 2,} the control device 4, the switching element _S up to the voltage _{v 1} becomes _{e max -e min, S vp,} S wp, S un, S vn, to control the status of the _{S wn,} voltage v ₂ controls the state of the switch element _S 1 to S ₄ so as to be _{V dc} (positive value). For example, if the space IV shown in FIG. 3, the control device 4, while the period _{a 1} similarly to the switch device _S Stay _up-, the voltage _{v 1} by turning on the _{S vn} and _e u -e _w, voltage v ₂ is turned on the switch element _S 2, _{S 3} so as to be _{V dc,} and turns off the other switching elements.

In the period _{a 3,} the control device 4, the switching element _S up to the voltage _{v 1} becomes _{e m, S vp, S wp} , S un, S vn, to control the status of the _{S wn,} voltage _{v 2} is V controlling the state of the switch element _S 1 to S ₄ so as to be _dc. If space IV shown example in Fig. 3, since the current _i mid _{(= i ev) e} from the equation (1) described above for is less than zero _{m = e max -e mid = e} u -e v , the control device 4, so that the voltage _{v 1} a _e u -e _v, and on switch element _S Stay _up-, the _{S vn.} Further, the control device 4 sets the _{voltage v 2} to V _dc and turns off the other switch elements by turning _{on the switch elements S 2} and S ₃ in the same manner as in the _{period a 2.}

In the period _{a 4,} the control device 4, the switching element _S up to the voltage _{v 1} becomes _{e min -e max, S vp,} S wp, S un, S vn, to control the status of the _{S wn,} voltage v ₂ controls the state of the switch element _S 1 to S ₄ so as to be _{V dc.} If space IV shown example in FIG. 3, the control device 4, so that the voltage _{v 1} a _e w -e _u, and on switch element _{S un,} the _{S wp.} Further, the control device 4 sets the _{voltage v 2} to V _dc and turns off the other switch elements by turning on the switch elements S ₂ and S ₃ in the same _{manner as in the periods a 2} and a _3.

In the period _{a 5,} the control device 4, the switching element _S up to the voltage _{v 1} becomes _{e min -e max, S vp,} S wp, S un, S vn, to control the status of the _{S wn,} voltage v ₂ controls the state of the switch element _S 1 to S ₄ so that the _{-V dc.} If space IV shown example in FIG. 3, the control device 4, the period _{a 4} similarly to the switch device _{S un,} by turning on the _{S wp,} the voltage _{v 1} and _e w -e _u. Further, the control unit 4, the voltage _{v 2} and _{-V dc} by turning on the switching element _S 1, _{S 4} as well as the period _{a 1,} which turns off the other switching elements.

In the period _{a 6,} the control device 4, the switching element _S up to the voltage _{v 1} becomes -e _m (inverse number of the input _{voltage), S vp, S wp,} S un, S vn, controls the state of _{S wn} as well as to control the state of the switch element _S 1 to S ₄ so that the voltage _{v 2} becomes _{-V dc.} If space IV shown example in FIG. 3, the control device 4, the switching element _S Stay _up-, by turning on the _{S vn,} the voltage _{v 1} and _e v -e _u. Further, the control unit 4, the voltage _{v 2} and _{-V dc} by turning on the period _a 1, _{a 5} similarly to the switching element _S 1, _{S 4,} and turns off the other switching elements.

Current _{i L,} the control device 4 above the switching element _{S up, S vp, S wp} , S un, S vn, S wn, as a result of controlling the S 1 to S _4, FIG. 5 (a as shown in), it soared plus minus with time _{a 1,} the period _a 2, keeping in _{a 3} approximately constant, sharply decreased from the positive in the period _{a 4} to minus, period _a 5, _{a 6} in substantially again It is a signal of a substantially square wave that shows the movement of keeping constant.

As shown in FIG. 5B, the control device 4 at the time of regeneration performs a repetitive operation of the frequency f having _{six periods b 1 to} b 6 having a total time length of 1 / f as one cycle. Hereinafter, the operation of the control device 4 in each period will be specifically described.

In the period _{b 1,} the control device 4, the switching element _S up to the voltage _{v 1} becomes _{e m, S vp, S wp} , S un, S vn, to control the status of the _{S wn,} voltage _{v 2} is V controlling the state of the switch element _S 1 to S ₄ so as to be _dc. If space IV shown example in Fig. 3, since the _{e m = e max -e mid =} e u -e v as described above, the control device 4, the voltage _{v 1} a _e u -e _v as to turn on switching element _S Stay _up-, the _{S vn.} Further, the control unit 4, turns on the switching element _S 2, _{S 3} so that the voltage _{v 2} becomes _{V dc,} and turns off the other switching elements.

In period _{b 2,} the control device 4, the switching element _S up to the voltage _{v 1} becomes _{e max -e min, S vp,} S wp, S un, S vn, to control the status of the _{S wn,} voltage v ₂ controls the state of the switch element _S 1 to S ₄ so as to be _{V dc.} For example, in the case of the space IV shown in FIG. 3, the control device 4 turns on the switch elements _Up and _{Swn so that the voltage v 1} becomes e _{u −} e _w. Further, the control device 4 sets the _{voltage v 2} to V _dc and turns off the other switch elements by turning _{on the switch elements S 2} and S ₃ in the same manner as in the _{period b 1.}

In the period _{b 3,} the control device 4, the switching element _S up to the voltage _{v 1} becomes _{e max -e min, S vp,} S wp, S un, S vn, to control the status of the _{S wn,} voltage v ₂ controls the state of the switch element _S 1 to S ₄ so that the _{-V dc.} For example, if the space IV shown in FIG. 3, the control device 4, the period _{b 2} similarly to switching element _S Stay _up-, by turning on the _{S wn,} the voltage _{v 1} and _e u -e _w. Further, the control unit 4, turns on the switching element _S 1, _{S 4} so that the voltage _{v 2} becomes _{-V dc,} and turns off the other switching elements.

In period _{b 4,} the control device 4, the switching element _S up to the voltage _{v 1} becomes _{-e m, S vp, S wp} , S un, S vn, to control the status of the _{S wn,} the voltage _{v 2} controlling the state of the switch element _S 1 to S ₄ so that the -V _dc. If space IV shown example in FIG. 3, the control device 4, so that the voltage _{v 1} becomes _e v -e _u, and on switch element _{S un,} the _{S vp.} Further, the control unit 4, the voltage _{v 2} and _{-V dc} by turning on the switching element _S 1, _{S 4} as well as the period _{b 3,} and turns off the other switching elements.

In period _{b 5,} the control device 4, the switching element _S up to the voltage _{v 1} becomes _{e min -e max, S vp,} S wp, S un, S vn, to control the status of the _{S wn,} voltage v ₂ controls the state of the switch element _S 1 to S ₄ so that the _{-V dc.} If space IV shown example in FIG. 3, the control device 4, so that the voltage _{v 1} a _e w -e _u, and on switch element _{S un,} the _{S wp.} Further, the control unit 4, the voltage _{v 2} and _{-V dc} by turning on the period _b 3, b ₄ similarly to switching element _S 1, _{S 4,} and turns off the other switching elements.

In period _{b 6,} the control device 4, the switching element _S up to the voltage _{v 1} becomes _{e min -e max, S vp,} S wp, S un, S vn, to control the status of the _{S wn,} voltage v ₂ controls the state of the switch element _S 1 to S ₄ so as to be _{V dc.} If space IV shown example in FIG. 3, the control device 4, the period _{b 5} similarly to the switch device _{S un,} by turning on the _{S wp,} the voltage _{v 1} and _e w -e _u. Further, the control device 4 sets the _{voltage v 2} to V _dc and turns off the other switch elements by turning on the switch elements S ₂ and S ₃ in the same _{manner as in the periods b 1} and b _2.

Current _{i L,} the switch element _S up as the control device 4 or _{more, S vp, S wp, S} un, S vn, S wn, as a result of controlling the S 1 to S _4, FIG. 5 (b as shown in), after maintaining a substantially constant in the period _b 1, _{b 2,} sharply decreases from the positive period _{b 3} to the negative, after almost kept constant again at time _b 4, _{b 5,} the period _{b 6} It becomes a signal of a substantially square wave that shows a movement of suddenly rising from minus to plus.

The controller 4 performs the above switching element _{S up, S vp, S wp} , S un, S vn, S wn, before controlling the S 1 to S _4, the power instruction value P input from the outside ^* time length of the period _{a 1 ~a 6, b 1 ~b} 6 based on (see FIG. 1) (switching element _{S up, S vp, S wp} , S un, S vn, S wn, S 1 ~S 4 The duty ratio) indicating the timing of changing each state is calculated. _{Specifically, the time lengths are the three duty ratios D 0 to} D ₂ shown in FIGS. 5 (a) and 5 (b). As can be understood from the description of each figure, in the present embodiment, _{the time lengths of the periods a 1} , a ₄ , b ₃ , and b ₆ are all set to D ₀ , and the periods a ₂ , a ₅ , and b _{2 are set.} , B ₅ are all D ₁ , and the periods a ₃ , a ₆ , b ₁ , and b ₄ are all D ₂ . The control unit 4, based on the calculated duty ratio _D 0 to D _2, switch element _S up as described _{above, S vp, S wp, S} un, S vn, S wn, S 1 ~S 4 of each state Take control. As a result, the relationship between the voltage and the current can be optimized in each phase of the three-phase AC, and as a result, the harmonics of the AC input current by the power conversion device 1 can be reduced. The details will be described below.

FIG. 6 is a flow chart showing a switching control process performed by the control device 4. As shown in the figure, the control device 4 first receives ^{an input of the power command value P *} from the outside (step S1; input reception step). Then, the duty ratio calculation process is executed based on the received power command value P ^{* (step S2. Calculation step).}

FIG. 7 is a flow chart showing details of the duty ratio calculation process. As shown in the figure, the control device 4 first calculates the input current command values _imax ^* and _imid ^{* based on the power command value P *} (step S10). The input current command values i _max ^* and i _mid ^* are the target values of the above-mentioned currents i _max and i _{mid *.} Specifically, the input current command values _imax ^* and _imid ^* are calculated using the following equation (3).

Next, the control unit 4, calculated input current command value _i ^max _*, based on the _{i mid} ^*, calculates an input current command value _i ^{m *} (step S11). Input current command value _i ^{m *} is the target value of the current _{i m} as described above, the input current command value _i ^max to the above-mentioned formula (2) _*, is calculated by substituting the _{i mid} ^*.

Subsequently, the control device _4, ⁱ m _{* =} a i m _{(D 0)} the duty ratio _{D 0} satisfying calculated by bisection method (step S12). However, the function _i m _{(D 0)} is a function expressed by the following equation (4) (first function). F in the formula (4) is the frequency f also shown in FIGS. 5 (a) and 5 (b), and L is the inductance of the reactor L. _{The duty ratio D 1} appearing in the equation (4) is expressed by the equation (5), and the variables A, B, and C in the equation (5) are expressed by the equation (6), respectively. ^{_{i m * = i m (D}} 0) by the duty ratio _{D 0} can be calculated, and, for the obtained duty ratio _{D 1} by equation (5) it is later explained in detail below.

Since ^{_{i m * = i m (D}} 0) it is difficult to solve analytically the control device 4 calculates a duty ratio _{D 0} by dichotomy. The details of this calculation will be described later. Then, the duty ratios D ₁ and D ₂ are calculated based on the calculated duty ratio D ₀ (step S13). The duty ratio D ₁ is calculated by the above equation (5). On the other hand, the duty ratio D ₂ is calculated by the following equation (7).

Return to FIG. The controller 4, based on the duty ratio _{D 0,} D 1, _{D 2} calculated in the above manner, switching element _S up as described _{above, S vp, S wp, S} un, S vn, S wn, S 1 ~ and controls the S ₄ (step S3. control step). Specifically, the calculated duty ratio _{D 0,} D 1, the control on the basis of the _{D 2} signal _{C up, C vp, C wp} , C un, C vn, C wn, to produce a C 1 -C _4, switch element _{S up, S vp, S wp} , S un, S vn, supplies S _wn, each of S 1 to S _4. As a result, the relationship between the voltage and the current is optimized in each phase of the three-phase AC, so that the harmonics of the AC input current by the power conversion device 1 can be reduced.

8 (a) is a signal waveform diagram showing the voltage _{e u, v 1,} v ₂ and the current _i eu, experimental results of power running of the waveform of _{i L,} FIG. 8 (b), voltage _e u, It is a signal waveform diagram which shows the experimental result of the waveform at the time of regeneration of v ₁ , v ₂ and the current i _eu , i _L. 8 (c) is an enlarged view of the region B shown in FIG. 8 (a), and FIG. 8 (d) is an enlarged view of the region C shown in FIG. 8 (b).

The experimental results shown in FIG. 8 are the results of an experiment in which the frequency f = 15.151 kHz and the winding ratio of the transformer 20 is 4: 1 (the number of turns of the coil 20a is four times the number of turns of the coil 20b). is there. Further, in the experiment of FIGS. 8 (a) and 8 (c), the power command value P ^* = 1 kW was set, and in the experiment of FIGS. 8 (b) and 8 (d), the power command value P ^* = -1 kW was set.

First, referring to FIGS. 8 (c) and 8 (d), it is understood that the power conversion device 1 according to the present embodiment can obtain a waveform similar to the theoretical waveform shown in FIG.

Referring now to FIG. 8 (a), at the time of power running and has a U-phase voltage e _u and U-phase input current i _eu and has substantially the same phase. Although not shown, voltage _{e v} and current _{i ev,} the same applies to the voltage _{e w} and current _{i ew.} Therefore, according to the power conversion device 1 according to the present embodiment, it is realized that the relationship between the voltage and the current is optimized in each phase of the three-phase AC, so that the harmonic of the AC input current in the power conversion device 1 Can be said to be reduced.

Further, referring to FIG. 8B, the U-phase voltage e _u and the U-phase input current i _eu are substantially in opposite phase during regeneration. Although not shown, voltage _{e v} and current _{i ev,} the same applies to the voltage _{e w} and current _{i ew.} Therefore, according to the power conversion device 1 according to the present embodiment, it can be said that not only the power running operation but also the regenerative operation (power transmission from the secondary side to the primary side) can be realized.

^{_{Hereinafter, i m * = i m (}} D 0) by the duty ratio _{D 0} can be calculated, and, for the obtained duty ratio _{D 1} by equation (5) will be described with reference to FIG. Since the motion during regeneration can be obtained by reversing the motion during power running, the following description will be focused on the motion during power running.

FIG. 9 schematically shows the waveforms of the voltages v ₁ , v ₂ and the current i _{L when (e max} −e _mid )> (e _mid −e _min ), e _mid <0, or i _{mid <0.} It is a signal waveform diagram which shows. Waveform of the figure in which the theoretical starting point for deriving a function i _{m (D 0),} and has a waveform that theoretically maximize the available transmission power. Incidentally, as a premise, the control device 4, so that the rectangular wave signal whose voltage _{v 2} transitions between _{V dc} and _{-V dc} at a period 1 / 2f, switching element _{S 1} constituting the AC / DC converter 30 ~ S ₄ Each state shall be controlled. Further, it is a condition for calculating the _{duty ratios D 0 to} D ₁ that the voltage v ₂ becomes a rectangular wave signal that transitions between _{V dc} and −V _{dc in} the period 1 / 2f.

Specifically explaining the waveform of FIG. 9, the control device 4 for realizing this waveform repeats the frequency f having _{eight periods c 1 to} c 8 having a total time length of 1 / f as one cycle. Do the action. Then, in the period c ₁ , the voltage v ₁ becomes e _max −e _min and the voltage v ₂ becomes −V _dc, and in the period c ₂ , the voltage v ₁ becomes e _max −e _min and the voltage v _{2 becomes e max −e min.} such that V _dc, the period _{c 3,} voltage _{v 1} is _e max _{-e mid} next, so that the voltage _{v 2} becomes _{V dc,} the period _{c 4,} the voltage _{v 1 e} mid _{-e min,} and the as the voltage _{v 2} becomes _{V dc,} the period _{c 5,} such that the voltage _{v 1} is _e min _{-e max,} and the voltage _{v 2} becomes _{V dc,} the period _{c 6,} voltage _{v 1} is _{e min} - e _max becomes, so that the voltage _{v 2} becomes _{-V dc,} during the period _{c 7,} so that the voltage _{v 1 e} mid _{-e max,} and the voltage _{v 2} becomes _{-V dc,} the period _{c 8,} a voltage v ₁ is _e min _{-e mid} next, so that the voltage _{v 2} becomes _{-V dc,} switching element _S up _{respectively, S vp, S wp, S} un, S vn, S wn, the state of S 1 to S ₄ To control. In the following description, as shown in FIG. 9, the time length of the period _c 1, _{c 5} and a _{d 0,} the time length of the period _c 2, _{c 6} and the _{d 1,} period _c 3, _{c 7} Let d ₂ be the time length of, and let d _{3 be} the time length of periods c ₄ and c ₈ . However, as shown in the following equation (8), _{the total of the time lengths d 0 to d 3} is 1. Since the periods c _{1 to} c ₄ and the periods c _{5 to} c ₈ are only reversed in sign, the description will be continued below focusing only on the _{periods c 1 to} c _4.

Assuming that the amount of change in the current i _L in each of the periods c _{1 to} c _{4 is Δi 0 to Δi 3} , it is expressed as the following equations (9) to (12), as can be understood from FIG. To.

_{Further, assuming that the amount of change in the current i L} from the beginning of the period c ₁ to the end of the _{period c 4} is Δi, Δi is expressed by the following equation (13) as can be understood from FIG.

Using Δi _{0 to Δi 3} and Δi, the average value i _{0_ave to} i _{3_ave} of the current i _{L in each of the periods c 1 to} c ₄ can be expressed as the following equations (14) to (17). ..

Equations (14) to (17) are expressed as the following equations (18) to (21) based on the equations (9) to (13), respectively.

_Further, by using the average values i _{0_ave to} i 3_ave, the above-mentioned currents _imax and _imid can be expressed as the following equations (22) and (23).

These currents _{i max, i mid} input current command value each _i ^max _*, by substituting the above equation (3) as _{i mid} ^*, the relational expression between the power command value ^{P *} and the time length _d 0 to d ₃ Is obtained. However, _{while there are four unknowns d 0 to d 3} , there are only three formulas for obtaining these, including the above formula (8), so to determine the _{time length d 0 to d 3.} There is room to add one condition.

Therefore, additional conditions are determined so that the power that can be transmitted is maximized. Specifically, focusing on the equation (23), so as not the absolute value of the current _{i mid} is small, and either zero time length _d 2, _{d 3} in accordance with the positive or negative value of the current _{i mid.} In other words, of the two elements of _{the current imid} shown on the right side of the equation (23), the element that reduces the absolute value of the _{current imid} is set to zero for either the _{time length d 2} or d _3. By setting it to zero. By setting any of the time lengths d ₂ and d ₃ to zero in this way, the signal waveform shown in FIG. 9 is transformed into the waveform shown in FIG. 5 (a). _{The relationship between the duty ratios D 0 to} D ₂ and the time lengths d _{0 to d 3} shown in FIG. 5 is expressed by the following equation (24).

Assuming the signal waveform shown in FIG. 5A, the equations (18) to (21) can be rewritten as the following equations (25) to (27). _{However, i 0_ave to} i _{2_ave} of the formulas (25) to (27) are average values of the currents i _{L in the periods a 1 to} a ₃ of FIG. 5 (a), respectively.

Further, the equations (22), (23), and (2) can be rewritten as the following equations (28) and (29).

By substituting the equations (25) to (27) and the equations (7) into the equations (28) and (29) and rearranging them, the following equation (30) is obtained.

Equation (30) is a binary simultaneous equation for _{D 0} and D _1. Therefore, formula (30) _{i m} and _i input current command value obtained from the equation (3) to each _{mid i} ^m _*, by substituting _{i mid} ^*, so that it is possible to obtain the _{D 0} and _{D 1} ..

Here, the right side of the first equation of equation (30) is nothing but a function _i m _{(D 0)} shown in equation (4). _Therefore, it can be said that ⁱ m _{* =} ⁱ m duty ratio _{D 0} by _{(D 0)} can be calculated.

Furthermore, solving the second equation of Formula (30) for _{D 1, D 1} in two ways as in the following equation (31) is obtained. However, A to C are those shown in the formula (6). The above-mentioned equation (5) corresponds to one of them (minus side). Therefore, it can be said that the _{duty ratio D 1} can be obtained by the equation (5). Hereinafter, the appropriateness of adopting D ₁ of the minus side of the D ₁ of the two types shown in formula (31) will be described.

By using the first equation of the equation (6), the second equation of the equation (6) can be modified as the following equation (32).

Substituting equation (32) into equation (31) gives the following equation (33).

Here, as is clear from the equation (6), A becomes zero when _{V dc} = e _max −e _min. Since there is A in the denominator of equation (33), D ₁ may diverge. _{Therefore, in order to investigate whether or not D 1} converges when A approaches zero, _{the limit of D 1} is calculated as shown in the following equation (34).

Equation (34) can be transformed as in the following equation (35). However, E on the right side is represented by the equation (36).

Here, since A ² << A (4D ₀ (e _max −e _min ) -4C), it can be approximated as ^{A 2 = 0.} Then, the equation (36) is transformed into the following equation (37).

Further, in general, the approximation of the following equation (38) holds for the square root. However, x << 1.

Using the approximation of equation (38), equation (37) is transformed into equation (39) below.

From the formula (35) and the formula (39), the following formula (40) is obtained.

From equation (40), _{it is understood that D 1} diverges when the sign is positive, but does not diverge when the sign is negative. Therefore, it can be said that it is appropriate to adopt a D ₁ of the minus side of the D ₁ of the two types shown in formula (31).

^{_{Above, i m * = i m (}} D 0) by the duty ratio _{D 0} can be calculated, and has been described to obtain the duty ratio _{D 1} by equation (5). _Next, ⁱ m _{* =} ⁱ m details about how to determine the duty ratio _{D 0} from _{(D 0),} will be described.

Figure 10 (a) ~ (c) are diagrams showing the outline of the function _i m _{(D 0).} 10 (a) shows the voltage _{V dc,} shows a case where the voltage _{e m} are both relatively small, FIG. 10 (b), the voltage _{V dc} relatively large, the case where the voltage _{e m} relatively smaller shown, FIG. 10 (c), the voltage _{V dc} relatively small, shows a case where the voltage _{e m} relatively large.

If the function _i m _{(D 0)} is the functional form in FIG. 10 (a), for 0 ≦ _D in the range of _{0 ≦ 0.5 i m (D 0} ) is a monotonically increasing, without problems by numerical D ₀ can be calculated. On the other hand, if the function i _{m (D 0)} is the functional form of FIG. 10 (b), the maximum value in the vicinity of the D 0 _{= 0,} since the minimum value is present, in the Newton's method using the gradient can not converge to a solution There is sex. If the function _i m _{(D 0)} is to be functional form in FIG. 10 (c), the value of _i m _{(D 0)} in the region of approximately _{D 0} ≦ 0.15 is complex. Therefore, it cannot be solved by calculating only real numbers, and complicated calculation is required to calculate _{D 0.}

Therefore, so we can determine the function i _{m (D 0)} readily D ₀ even were any functional form, and to calculate the D ₀ using dichotomy. Of the two initial values dichotomies, the larger is the _i m _{(D 0)} 0.5 which is substantially maximum, the smaller _is, i m smallest _{D 0} to _{(D 0)} is not a complex number 0. The larger of 0 is used. When this condition is used, if a solution exists, it is possible to sandwich the solution in the real number region by the initial value, so that an approximate solution can always be obtained by a finite number of calculations.

_The minimum of _{D 0} where i m _{(D 0)} is not a complex number, it may be determined as follows. First, the _{condition that D 1} is a real number is the following equation (41) from the equation (5).

Substituting Eq. (6) into Eq. (41) and _{solving for D 0} gives the following Eq. (42). However, the variables A', B', and C'in the equation (42) are expressed as in the equation (43), respectively.

i _m smallest _{D 0} to _{(D 0)} is not a complex number is the smallest _{D 0} satisfying the equation (42). _{Therefore, the smallest D 0} satisfying the equation (42) and the larger of 0.0 may be used as the smaller of the two initial values of the dichotomy method.

As described above, according to the controller 4 of the power conversion apparatus 1 according to this embodiment, the switch element _S up based on the power command value ^{_{P *, S vp, S wp}} , S un, S vn, S wn , S _{1 to} S _{4 Calculate the duty ratios D 0 to} D ₂ indicating the timing to change each state, and based on the calculated duty ratios D _{0 to} D ₂ , the switch elements S _up , S _vp , _{Sw p} , S _{un, S} vn, _S wn, since the control state of S 1 to S _4, switching element _S up at the right _{time, S vp, S wp, S} un, S vn, S wn, S 1 ~S It becomes possible to control the state of _4. Therefore, as shown in FIG. 8, it is possible to reduce the harmonics of the AC input current in the power conversion device 1 which is an isolated AC / DC converter to which the matrix converter 10 is applied.

Further, according to the control device 4 of the power conversion device 1 according to the present embodiment, it is possible to calculate the _{duty ratios D 0 to} D ₂ indicating the optimum timing based on ^{the power command value P *.}

Further, according to the control device 4 of the power conversion device 1 according to the present embodiment, not only the power running operation but also the regenerative operation can be performed.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and the present invention can be implemented in various embodiments without departing from the gist thereof. Of course.

For example, in the above embodiment, it has been _{described that the duty ratios D 0 to} D ₂ are calculated by numerical calculation each time ^{the power command value P *} is input, but the power command value P ^* and the duty ratio D _{0 to} D _{2 are calculated.} When the correspondence relationship with is determined in advance, a lookup table showing the correspondence relationship is created and stored in advance ^{, and when the input of the power command value P *} is accepted, the corresponding duty ratio D ₀ to The _{duty ratios D 0 to} D ₂ may be calculated by _{reading D 2} from this look-up table.

1 Power converter 2 System power supply 3 Load 4 Controller 10 Matrix converter 20 Transformer 20a, 20b Coil 30 AC / DC converter C1 Capacitor Cf Input capacitor L Reactor Lf AC reactor S _{1 to} S _{4 One-} way switch element S _up , S _{bp , S wp, S un, S} vn, S wn bidirectional switch element

Claims (6)

A transformer with first and second coils that are magnetically coupled to each other,
A first one-way switch element, one end connected to a fifth node constituting one end of the load, the other end connected to a third node forming one end of the second coil, and one end of the load. A second one-way switch element connected to a sixth node constituting the other end, the other end connected to the third node, one end connected to the fifth node, and the other end connected to the second node. A third one-way switch element connected to a fourth node constituting the other end of the coil, and a third one end connected to the sixth node and the other end connected to the fourth node. An AC / DC converter with 4 one-way switch elements,
Both first connected to a seventh node corresponding to the first phase of three-phase AC, and the other end connected to a first node connected to one end of the first coil via a reactor. A second bidirectional switch element, one end connected to an eighth node corresponding to the second phase of the three-phase AC, the other end connected to the first node, and one end connected to the three-phase. A third bidirectional switch element connected to a ninth node corresponding to the third phase of AC, the other end connected to the first node, one end connected to the seventh node, and the other end. A fourth bidirectional switch element connected to a second node constituting the other end of the first coil, one end connected to the eighth node and the other end connected to the second node. A power conversion device having a fifth bidirectional switch element and a matrix converter having a sixth bidirectional switch element having one end connected to the ninth node and the other end connected to the second node. It is a control device of
An input reception step that accepts the input of the power command value, and
Based on the power command value, a calculation step of calculating a duty ratio indicating the timing of changing the state of each of the first to fourth one-way switch elements and the first to sixth bidirectional switch elements, and
A control device comprising executing a control step for controlling the states of the first to fourth unidirectional switch elements and the first to sixth bidirectional switch elements based on the duty ratio. The control step is configured to perform a repetitive operation with the first to sixth periods as one cycle.
The control device according to claim 1, wherein the duty ratio is a time length of the first to sixth periods. The maximum of the first to third AC voltages for each of the first to twelfth spaces determined according to the phases of the first to third AC voltages corresponding to the first to third phases, respectively. The maximum phase voltage is defined as the maximum phase voltage, the intermediate voltage among the first to third AC voltages is defined as the intermediate phase voltage, and the minimum voltage among the first to third AC voltages is defined as the minimum phase voltage. Among the first to third currents flowing through the seventh to ninth nodes, the one corresponding to the intermediate phase voltage is defined as the intermediate phase current, and when the intermediate phase current is larger than zero, the intermediate phase voltage is used. When the intermediate phase current is smaller than zero, the input voltage is equal to the voltage obtained by subtracting the minimum phase voltage and equal to the voltage obtained by subtracting the intermediate phase voltage from the maximum phase voltage.
The control step is
In the first period, the first voltage, which is the voltage of the first node with respect to the voltage of the second node, becomes a voltage obtained by subtracting the minimum phase voltage from the maximum phase voltage. The first to sixth bidirectional switch elements are controlled so that the second voltage, which is the voltage of the fourth node with respect to the voltage of the third node, becomes a negative value while controlling the state of the first to sixth bidirectional switch elements. Control the state of the one-way switch element of 4 and
In the second period, the state of the first to sixth bidirectional switch elements is controlled so that the first voltage becomes a voltage obtained by subtracting the minimum phase voltage from the maximum phase voltage, and the state of the first to sixth bidirectional switch elements is controlled. The state of the first to fourth unidirectional switch elements is controlled so that the second voltage becomes a positive value.
In the third period, the state of the first to sixth bidirectional switch elements is controlled so that the first voltage becomes the input voltage, and the second voltage becomes a positive value. To control the state of the first to fourth one-way switch elements,
In the fourth period, the state of the first to sixth bidirectional switch elements is controlled so that the first voltage becomes a voltage obtained by subtracting the maximum phase voltage from the minimum phase voltage. The state of the first to fourth unidirectional switch elements is controlled so that the second voltage becomes a positive value.
In the fifth period, the state of the first to sixth bidirectional switch elements is controlled so that the first voltage becomes a voltage obtained by subtracting the maximum phase voltage from the minimum phase voltage. The state of the first to fourth unidirectional switch elements is controlled so that the second voltage becomes a negative value.
In the sixth period, the state of the first to sixth bidirectional switch elements is controlled so that the first voltage becomes the reciprocal of the input voltage, and the second voltage has a negative value. The control device according to claim 2, wherein the state of the first to fourth one-way switch elements is controlled so as to be. Among the first to third currents, the one corresponding to the maximum phase voltage is defined as the maximum phase current, and when the intermediate phase current is larger than zero, it is equal to the maximum phase current and the intermediate phase current is from zero. If it is small, the input current is a current equal to the sum of the maximum phase current and the intermediate phase current.
The calculation step is
A step of calculating the command values of the maximum phase current and the intermediate phase current based on the power command value, and
A step of calculating the command value of the input current based on the calculated command values of the maximum phase current and the intermediate phase current, respectively.
The first duty ratio such that the calculated command value of the input current and a predetermined first function, which is a function of the first duty ratio indicating the time lengths of the first and fourth periods, are equal to each other. And the steps to derive
Based on the first duty ratio, a second duty ratio indicating the time length of each of the second and fifth periods, and a third duty indicating the time length of each of the third and sixth periods. The control device according to claim 3, further comprising a step of calculating a ratio. The other end of each of the first to third bidirectional switch elements is connected to the first node via a common reactor.
In the first function, the first duty ratio is D ₀ , the inverse of the total time lengths of the first to sixth periods is f, the inductance of the reactor is L, and the voltage of the sixth node is relative to the voltage of the sixth node. the voltage _{V dc} of the fifth node, the maximum phase voltage _{e max,} the minimum phase voltage _{e min,} the input voltage _{e m,} the when the intermediate phase current and _{i mid,} the following equation (2) using variable a, B, C shown in the variable _{D 1} and equation (3) shown in, represented by _i m _{(D 0)} shown in the following formula (1)

The control device according to claim 4. The control step becomes a square wave signal in which the second voltage transitions between a predetermined positive voltage and a predetermined negative voltage at a period corresponding to half of the total time length of the first to sixth periods. The control device according to any one of claims 3 to 5, wherein the state of the first to fourth unidirectional switch elements is controlled as described above.

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