JP2010104076A - Power converter circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power converter circuit generating no current ripple. <P>SOLUTION: The power converter circuit 100 is configured by adding a bidirectional switch having a switch element Q<SB>0</SB>composed of IGBTs and a diode D<SB>0</SB>connected in inverse-parallel, to a configuration of an impedance source inverter. The switch element Q<SB>0</SB>is turned on when regenerative current from, for example, a three-phase induction motor as an external load connected to three-phase alternating-current terminals A, B, and C is charged into a rechargeable battery V<SB>0</SB>. The switch element Q<SB>0</SB>is turned on also when current passes through an inductor L<SB>1</SB>and an inductor L<SB>2</SB>in opposite directions. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a power conversion circuit that generates AC power from a secondary battery (rechargeable battery) and a control method thereof. The present invention is effective when charging a secondary battery (rechargeable battery) when regenerative power is input.

Patent Document 1 and Non-Patent Documents 1 and 2 propose impedance source inverters by Peng et al. In the impedance source inverter, an impedance part combining two inductors and two capacitors is disposed between a power supply part and a three-phase switching part, and six transistor switches of the three-phase switching part are subjected to pulse width modulation ( On / off control by PWM) enables conversion and output from, for example, a DC power supply to a three-phase AC.
The feature of the impedance source inverter is that there is no problem even if the dead time of the switching element disappears due to noise and a short through state occurs, so that high reliability of the inverter can be achieved, high switching frequency of the inverter can be achieved, Furthermore, a voltage higher than that of the constant-voltage DC power source can be used as a three-phase AC output. Here, the dead time refers to a state in which the upper and lower switches are turned off during the reverse rotation of the upper and lower switches when the upper and lower switches of the respective phases cannot be turned on simultaneously.
USP 7130205 IEEE Transactions on Industry Applications, vol. 39, no. 2, pp. 504-510, March / April 2003 Proc. of IEEE IAS 2005 pp. 1253-1260

The configuration of the impedance source inverter and the switch control will be described focusing on the description of Non-Patent Document 2.
FIG. 11 is two circuit diagrams showing a configuration of an impedance source inverter 900 according to a conventional example.
FIG. As shown in A, the positive electrode of the diode D is connected to the positive electrode side of the constant-voltage DC power supply _Vdc that is not chargeable. The first terminal of the first inductor L ₁ is connected to the negative electrode of the diode D, and the second terminal, which is the other end of the first inductor L ₁ , is connected to the first pole P of the three-phase switching unit S _3ph . ing. A first terminal which is a positive electrode of the first capacitor C ₁ is further connected to the negative electrode of the diode D. The second terminal, which is the negative electrode of the first capacitor C ₁ , is connected to the second pole N of the three-phase switching unit S _3ph .
The first terminal, which is the positive electrode of the second capacitor C ₂ , is connected to the first pole P of the three-phase switching unit S _3ph . The second terminal is a second negative electrode of the capacitor C ₂ is connected to the negative pole of the constant pressure DC power source V _dc not rechargeable.
The first terminal of the _second inductor L ₂ is connected to the second pole N of the three-phase switching unit S _3ph . The second terminal of the second inductor L ₂ is connected to the negative pole of the constant pressure DC power source V _dc not rechargeable.

FIG. The three-phase switching unit S _{3ph of A} has the first pole P and the second pole N as the DC power supply side terminals, and the terminals A, B, and C as the three-phase AC side terminals, which are _composed of six transistors and six diodes. It is connected with.
A switch element Q _ap made of, for example, IGBT is connected between the first pole P and the terminal A. The switch element Q _ap is a switch that can switch between current interruption and current conduction from the first pole P to the terminal A by a control voltage. A diode D _ap is connected to the switch element Q _ap in antiparallel. That is, the diode D _ap always enables conduction of current from the terminal A to the first pole P.
A switch element Q _an made of, for example, IGBT is connected between the terminal A and the second pole N. The switch element Q _an is a switch that can switch between interruption of current and conduction of current from the terminal A to the second pole N by a control voltage. Further, a diode _Dan is connected to the switch element Q _an in antiparallel. That is, the diode _Dan always allows conduction of current from the second pole N to the terminal A.
These diodes D _ap and D _an may be connected to an element independent of the switch elements Q _ap and Q _an made of, for example, IGBT. Alternatively, the diodes D _ap and _Dan may be parasitic diodes of switch elements Q _ap and Q _an made of, for example, IGBT, respectively.

Exactly the same, the switching element Q _bp and the diode D _bp connected in antiparallel are connected between the first pole P and the terminal B, and are connected in antiparallel between the terminal B and the second pole N. The switching element Q _bn and the diode D _bn are connected. Further, a switch element Q _cp and a diode D _cp connected in antiparallel are connected between the first pole P and the terminal C, and a switch connected in antiparallel between the terminal C and the second pole N. The element Q _cn and the diode D _cn are connected.

FIG. B is a circuit diagram of a simplified impedance source inverter 900 following the method described in Non-Patent Document 2. FIG. For example, a three-phase induction motor is connected to the three terminals A, B, and C of the three-phase switching unit S _3ph. Since it can be regarded as a constant current source state, the constant current source is described as being between the first pole P and the second pole N.

12 is shown in FIG. It is a figure which shows the on-off state in a certain time area of the six switch elements demonstrated by 3 (b). In the PWM control, a time interval in which a positive voltage is applied to the terminal B and a negative voltage is applied to the terminals A and C is shown.
Time period T _s is composed of so-called short-through state in which the time interval T _0, the time interval T ₁₁ is a zero vector state, active power time interval T _a which supplies the time interval T ₁₂ is a zero vector state .
The control states of the six switches in each time interval are as follows.
In the time interval T ₀ in the short-through state, the gate potentials of the six switch elements Q _ap , Q _an , Q _bp , Q _bn , Q _cp, and Q _cn are High and are in a conductive state. That is, FIG. In the circuit diagram of A, current flows from the first pole P to the second pole N through two switch elements by three paths. This is shown in FIG. In the circuit diagram of B, the constant current source between the first pole P and the second pole N disappears, and the first pole P and the second pole N are directly connected.
In the time interval T ₁₁ in the zero vector state, the gate potentials of the three switch elements Q _an , Q _bn, and Q _cn are High, and are in a conductive state. On the other hand, the gate potentials of the three switch elements Q _ap , Q _bp, and Q _cp are Low and are in the cut-off state. That is, FIG. In the circuit diagram of A, all of the three terminals A, B, and C are disconnected from the first pole P and are electrically connected to the second pole N. At this time, FIG. In the circuit diagram of B, the constant current source between the first pole P and the second pole N disappears, and the first pole P and the second pole N are disconnected.
In the first half about 4/5 of the time interval T _a which supplies the active power, the three switching elements Q _an,, the gate potential of the Q _bp and Q _cn is High, is conductive. On the other hand, the gate potentials of the three switch elements Q _ap , Q _bn, and Q _cp are Low and are in the cut-off state. That is, the current flows from the first pole P to the terminal B, drives a three-phase induction motor as an external load, for example, and flows from the terminal A and the terminal C to the second pole N.
In about 1/5 second half of the active power time interval T _a which supplies the three switching elements Q _ap, the gate potential of the Q _bp and Q _cn is High, is conductive. On the other hand, the gate potentials of the three switch elements Q _an , Q _bn, and Q _cp are Low and are in a cut-off state. That is, the current flows from the first pole P to the terminals A and B, drives a three-phase induction motor, for example, an external load, and then flows from the terminal C to the second pole N.
In the time interval T ₁₂ is a zero vector state, the gate potential of the three switching elements Q _ap, Q _bp and Q _cp is High, is conductive. On the other hand, the gate potentials of the three switch elements Q _an , Q _bn, and Q _cn are Low and are in the cut-off state. That is, FIG. In the circuit diagram of A, all of the three terminals A, B, and C are disconnected from the second pole N and are electrically connected to the first pole P. At this time, FIG. In the circuit diagram of B, the constant current source between the first pole P and the second pole N disappears, and the first pole P and the second pole N are disconnected.

In the time interval T _s of FIG. The operation of the impedance source inverter 900 of B is as shown in FIG. 13 (part of FIG. 2 of Non-Patent Document 2 is changed).
First, FIG. As in A, in the time interval T ₀ in the short-through state, FIG. From the circuit diagram of B, the constant current source between the first pole P and the second pole N disappears, and the first pole P and the second pole N are directly connected. In this case, for example, first it is sufficiently higher than the capacitor C ₁ and the second capacitor C ₂ of the voltage constant pressure DC power source V _dc, from constant pressure DC power source V _dc first inductor L ₁ and the first capacitor no current flows in C _1. Similarly, no current flows from the second inductor L ₂ or the second capacitor C ₂ to the constant voltage DC power source V _dc . Specifically, FIG. As shown in A, the diode D is extinguished, and current flows in the direction of the arrow shown in the two closed circuits. That is, the first inductor L ₁ is charged by the discharge of the first capacitor C ₁ , and the second inductor L ₂ is charged by the discharge of the second capacitor C ₂ .

Next, FIG. As in B, in the time interval T ₁₁ is a zero vector state, FIG. The constant current source between the first pole P and the second pole N disappears from the circuit diagram of B, and the current flows in the direction of the arrow shown in the state where the first pole P and the second pole N are disconnected. . That is, the second capacitor C ₂ is charged by the discharge of the first inductor L ₁ and the constant voltage DC power source V _dc . Further, the first capacitor C ₁ is charged by the discharge of the constant voltage DC power source V _dc and the second inductor L ₂ .

Next, FIG. As in C, and the time interval T _a which supplies the active power, FIG. In the state of the circuit diagram of B, a current flows in the direction of the illustrated arrow. A part of the current of the first inductor L ₁ flows to the first pole P and drives, for example, a three-phase induction motor, which is an external load, to return to the second pole N. Further, the second capacitor C ₂ is charged by the discharge of the constant voltage DC power source V _dc and the first inductor L ₁ , and the first capacitor C ₁ is charged by the discharge of the constant voltage DC power source V _dc and the second inductor L _2. The state to be continued.
At this time, the external load may be considered as a constant current source, and is assumed to be the constant current I _i now. If the current I _{L1 of} the first inductor L ₁ is greater than or equal to I _i , FIG. The state of C continues. If the first inductor L ₁ of the current I _L1 is I _i / 2 or less than I _i, 13. In the state C, the first capacitor C ₁ and the second capacitor C ₂ are not charged but discharged. Note that the current I _L2 of the second inductor L ₂ is always equal to the current I _L1 of the first inductor L ₁ .

The total potential of the potential of the constant-voltage DC power supply V _{dc and} the potential of the first inductor L ₁ during discharge is smaller than the second capacitor C _2, and the potential of the constant-voltage DC power supply V _dc and the second inductor L ₂ during discharge are discharged. When the total potential of the first and second potentials becomes smaller than that of the first capacitor C ₁ , FIG. As in D, no current flows from the constant pressure DC power supply V _dc . On the other hand, FIG. Current continues to flow in the direction of the arrow indicated by D. That is, according to the first discharge of the capacitor C _1, the first inductor L _1, first pole P, the external load is a example 3-phase induction motor, a circuit of the second pole N, a second capacitor C ₂ discharges in accordance, first pole P, which is an external load, for example, a three-phase induction motor, the second pole N, a second circuit of the inductor L _2. During this time, with respect to current I _i of the constant current source which is external load, the first inductor L ₁ of the current I _L1 is the current I _L2 of the second inductor L ₂ becomes constant at I _i / 2.

Thereafter, in the time interval T ₁₂ is a zero vector state, a constant current source which is external load is disconnected, the current is cut off. The first state is shown in FIG. At B, the first capacitor C ₁ and the second capacitor C ₂ are not charged but discharged. When zero vector state even after this continues, the first inductor L ₁ of the current I _L1 and the second current I _L2 in the inductor L ₂ converges rapidly to zero. Note that initiating a short-through state and the first inductor L ₁ of the current I _L1 and the second inductor L ₂ of the current I _L2 is the next switch state prior to converge to 0 (Figure 13.A) Is also possible.

FIG. 14 shows two patterns of changes in the current I _L1 of the first inductor L ₁ .
FIG. A, in the time interval T ₁₂ is a zero vector state is the next switch state before the first inductor L ₁ of the current I _L1 and the second current I _L2 in the inductor L ₂ converges to 0 Short This is a case of starting the through state.
In the time interval T ₀ in the short-through state, FIG. A circuit state of A, FIG. As shown in the time period T ₀ of A, the first current I _L1 of inductor L ₁ is increased to immediately I _pk from the lowest value I _n. The change of the current I _L1 should originally draw a relaxation curve, but a straight line was shown according to Non-Patent Document 2.
In the time interval T ₁₁ in the zero vector state, FIG. B circuit state, FIG. As indicated by the time interval T ₁₁ of A, the current I _L1 of the first inductor L ₁ decreases from the maximum value I _pk . At this time, the change in the current I _L1 again showed a straight line according to Non-Patent Document 2.
The time interval T _a which supplies the active power, FIG. FIG. 13 shows a time interval T ₂ which is a circuit state of C. It is divided into a time interval T ₃ which is a circuit state of D.
FIG. In the time interval T ₂ which is the circuit state of C, FIG. As indicated by A, the current I _L1 of the first inductor L ₁ continues to decrease from the time interval T ₁₁ toward I ₀ = I _i / 2. Again, the change in the current I _L1 showed a straight line according to Non-Patent Document 2.
FIG. In the time interval T ₃ which is the circuit state of D, FIG. As indicated by A, the current I _L1 of the first inductor L ₁ is constant at I ₀ = I _i / 2.
In the time interval T ₁₂ in the zero vector state, FIG. B circuit state, FIG. As indicated by the time interval T ₁₂ of A, the current I _L1 of the first inductor L ₁ decreases rapidly from I ₀ = I _i / 2. Before the current I _{L1 of} the first inductor L ₁ becomes zero, the next short-through state is started. Also at this time, the change in the current I _L1 showed a straight line according to Non-Patent Document 2.

FIG. B, in the time interval T ₁₂ is a zero vector state, after the first inductor L ₁ of the current I _L1 and the second current I _L2 in the inductor L ₂ has converged to 0, the next switch state Short This is a case where a time interval occurs before the through state is started.
In the time interval T ₀ in the short-through state, FIG. A circuit state of A, FIG. As indicated by the time interval T ₀ of B, the current I _L1 of the first inductor L ₁ immediately rises from the lowest value 0 to I _pk .
In the time interval T ₁₁ in the zero vector state, FIG. B circuit state, FIG. As indicated by the time interval T ₁₁ of B, the current I _L1 of the first inductor L ₁ decreases from the maximum value I _pk .
FIG. In the time interval T ₂ which is the circuit state of C, FIG. As indicated by B, the current I _L1 of the first inductor L ₁ continues to decrease from the time interval T ₁₁ toward I ₀ = I _i / 2.
FIG. In the time interval T ₃ which is the circuit state of D, FIG. As indicated by B, the current I _L1 of the first inductor L ₁ is constant at I ₀ = I _i / 2.
In the time intervals T ₄ and T ₅ in the zero vector state, FIG. B and FIG. The circuit state of E. First, FIG. As indicated by the time interval T ₄ of B, the current I _L1 of the first inductor L ₁ decreases rapidly from I ₀ = I _i / 2 to 0. After this, after the time interval T _{5 has} elapsed, the short-through state is started.

FIG. The impedance source inverter 900 of A is a short time when the external load connected to the three terminals A, B and C is small, or when the small inductors L ₁ and L ₂ inside the impedance source inverter 900 are used. However, there is a discontinuous time interval in which the current is zero. This is shown in Non-Patent Document 2, and FIG. This means the state of B.
In the discontinuous state where the current becomes zero, the potential charged in the capacitors C ₁ and C ₂ cannot be controlled, and the potential of the three-phase output may become uncontrollable.
In Non-Patent Document 2, this is solved by adjusting each time interval when controlling the on / off of the six switches of the three-phase switching unit.
An object of the present invention is to eliminate a time interval in a discontinuous state in which an inductor current becomes 0 by an additional controllable configuration.
Another object is to boost the regenerative current to a secondary battery (rechargeable battery) for charging.

The invention according to claim 1 is a DC power supply unit having a secondary battery and a first bidirectional switch, an impedance unit having first and second inductors, and first and second capacitors, and 6 A power conversion circuit having at least a second bidirectional switch and a three-phase switching unit having a three-phase input / output terminal,
Each of the first and second bidirectional switches includes a transistor that conducts in one direction by a control potential, and a diode connected in reverse parallel to the transistor.
The impedance unit is configured such that the first terminal of the first inductor and the first terminal of the first capacitor are connected to the positive side of the DC power supply unit, the second terminal of the first inductor, and the second terminal of the second capacitor. One terminal is connected to the first pole side of the three-phase switching unit, the first terminal of the second inductor and the second terminal of the first capacitor are connected to the second pole side of the three-phase switching unit, The second terminal of the second inductor and the second terminal of the second capacitor are connected to the negative electrode side of the DC power supply unit,
The three-phase switching unit controls three bidirectional switches, each consisting of three sets of six second bidirectional switches connected in series in the same direction and connected in parallel in the same direction. By doing so, current flows from the first pole side to the second pole side, and the three-phase input / output terminals are connected to the midpoints of the two second bidirectional switches of each of the three sets of switch arrays. And
In at least one set of switch rows of the three-phase switching unit, when both of the two second bidirectional switches constituting it are on, the first bidirectional switch can be turned off to discharge the secondary battery. In other cases, the power conversion circuit includes a control device that controls the first bidirectional switch to be turned on so that current can flow in the direction of charging the secondary battery. .

According to a second aspect of the present invention, there is provided a DC power source unit having a secondary battery and a first bidirectional switch, an impedance unit having first and second inductors, and first and second capacitors, and 6 A power conversion circuit having at least a second bidirectional switch and a three-phase switching unit having a three-phase input / output terminal,
Each of the first and second bidirectional switches includes a transistor that conducts in one direction by a control potential, and a diode connected in reverse parallel to the transistor.
The impedance unit is configured such that the first terminal of the first inductor and the first terminal of the first capacitor are connected to the positive side of the DC power supply unit, the second terminal of the first inductor, and the second terminal of the second capacitor. One terminal is connected to the first pole side of the three-phase switching unit, the first terminal of the second inductor and the second terminal of the first capacitor are connected to the second pole side of the three-phase switching unit, The second terminal of the second inductor and the second terminal of the second capacitor are connected to the negative electrode side of the DC power supply unit,
The three-phase switching unit controls three bidirectional switches, each consisting of three sets of six second bidirectional switches connected in series in the same direction and connected in parallel in the same direction. By doing so, current flows from the first pole side to the second pole side, and the three-phase input / output terminals are connected to the midpoints of the two second bidirectional switches of each of the three sets of switch arrays. And
The power conversion circuit further includes a boost switch circuit that is controlled to start when the regenerative current input from the input / output terminal of the three-phase switching unit is charged to the secondary battery.

The invention according to claim 1 is the addition of a first bidirectional switch composed of a transistor that conducts in one direction by a control potential and a diode connected in antiparallel to the conventional impedance source inverter. is there.
Since the first bidirectional switch has a diode connected in the forward direction, no switch control is required when discharging from the secondary battery. When the transistor of the first bidirectional switch is turned on, the secondary battery is charged. That is, according to the present invention, the regenerative current can be reused from, for example, a three-phase induction motor that is an external load connected to the three-phase switching unit.
Here, as shown in the following examples, there is no discontinuous time interval in which the inductor current becomes zero. That is, according to the present invention, since there is no discontinuous state in which the current becomes zero, the potential charged in the capacitor can always be controlled, and the potential of the three-phase output does not become uncontrollable.

  In the invention according to claim 2, since the conventional impedance source inverter charges the capacitor with a potential higher than the potential on the DC power supply side and outputs three-phase AC power, conversely, the regenerative current is supplied to the secondary battery. When charging, a booster circuit is provided which charges a secondary battery after charging a capacitor and an inductor with a potential higher than the potential of the regenerative current.

The present invention can be configured by combining any available element in addition to the three documents of the impedance source inverter. As the bidirectional switch, a reverse conducting IGBT or any other element may be used. At this time, instead of a bidirectional switch transistor composed of a transistor and a diode, any element that can be switched between conduction (on) and cutoff (off) by voltage control can be used.
In the following examples, only the secondary battery (rechargeable battery) is shown. However, it is obvious that it can be used for a circuit using a fuel cell or other non-chargeable battery in combination with an easy circuit configuration.

FIG. A is a circuit diagram showing a configuration of a power conversion circuit 100 according to a first specific example of the present invention. FIG. The power conversion circuit 100 of A uses a secondary battery (rechargeable battery) V ₀ instead of the constant-voltage DC power supply V _dc in the impedance source inverter 900 of FIG. 11, and uses a diode D as a switching element Q ₀ and a diode. This is a bidirectional switch in which D ₀ is connected in antiparallel. As described above, the diode D _{0 of the} bidirectional switch may use an IGBT parasitic diode, or may connect another diode in antiparallel.
The switch element Q ₀ made of IGBT is turned on when charging the secondary battery (rechargeable battery) V ₀ . In the state where the switch element Q ₀ is off, the secondary battery (rechargeable battery) V ₀ is not charged even though it is discharged through the diode D ₀ .

FIG. A configuration of the two inductors L ₁ and L ₂ , the two capacitors C ₁ and C ₂ , and the three-phase switching unit S _3ph , which are other parts of the power conversion circuit 100 of FIG. Since it is exactly the same as the impedance source inverter 900 of A, detailed description is omitted.
FIG. B shows a state where, for example, a three-phase induction motor as an external load is connected to the three-phase AC input / output terminals A, B, and C of the power conversion circuit 100. In a state where active power is supplied, it can be considered that a constant current source is connected between the first pole P and the second pole N.

FIG. 2 is a circuit diagram showing five states of the current of the power conversion circuit 100 according to the present embodiment, _{depending on} the switch state of the three-phase switching unit S _{3ph and} the state of the switch element Q ₀ . FIG. 6 is five circuit diagrams showing five states of current of the conversion circuit 100.
First, the switching element Q ₀ is turned off when the three-phase switching unit S _3ph is in a short-through state. At this time, FIG. FIG. 13 shows an impedance source inverter 900 of A. FIG. A similar state to A. That is, FIG. As in A, the first pole P and the second pole N are directly connected, and the voltages of the first capacitor C ₁ and the second capacitor C ₂ are sufficiently higher than the secondary battery V _0. . Then FIG. As in A, the diode D ₀ is extinguished, and current flows in the direction of the arrow shown in the two closed circuits. That is, the first inductor L ₁ is charged by the discharge of the first capacitor C ₁ , and the second inductor L ₂ is charged by the discharge of the second capacitor C ₂ .

Next, the three-phase switching unit S _3ph is set to the zero vector state, and the switch element Q ₀ is turned on. At this time, FIG. FIG. 13 shows an impedance source inverter 900 of A. FIG. It becomes the same state as B. That is, FIG. As in B, the second capacitor C ₂ is charged by the discharge of the secondary battery V ₀ and the first inductor L ₁ . Further, the first capacitor C ₁ is charged by the discharge of the secondary battery V ₀ and the second inductor L ₂ .

Next, the three-phase switching unit S _3ph is in a state of supplying active power, and the switch element Q ₀ is kept on. At this time, FIG. FIG. 13 shows an impedance source inverter 900 of A. FIG. It becomes the same state as C. That is, FIG. As shown in C, a part of the current of the first inductor L ₁ flows to the first pole P and drives, for example, a three-phase induction motor, which is an external load, to return to the second pole N. Further, the second capacitor C ₂ is charged by the discharge of the secondary battery V ₀ and the first inductor L ₁ , and the first capacitor C ₁ is charged by the discharge of the secondary battery V ₀ and the second inductor L _2. The state to be continued.
FIG. In C, if the current I _{L1 of} the first inductor L ₁ exceeds the current I _{i of the} external load, if the current I _{L1 of} the first inductor L ₁ is equal to the current I _{i of the} external load, the first Although the case where the current I _L1 of the inductor L ₁ is smaller than the current I _{i of the} external load and exceeds I _i / 2 is shown in one figure, it is as follows when disassembled.
First, when the current I _{L1 of} the first inductor L ₁ decreases and becomes equal to the current I _{i of the} external load, FIG. As in D, charging of the first capacitor C ₁ and the second capacitor C ₂ stops.
Next, when the current I _{L1 of} the first inductor L ₁ decreases and falls below the external load current I _i , FIG. As in E, the first capacitor C ₁ and the second capacitor C _{2 are} discharged. Further, the secondary battery V ₀ continues to be discharged. This state continues until the current I _L1 of the first inductor L ₁ becomes half the current I _i of the external load.

Next, when the current I _{L1 of} the first inductor L ₁ decreases and becomes half of the current I _i of the external load, FIG. As in A, the secondary battery V ₀ stops discharging.
Next, when the current I _{L1 of} the first inductor L ₁ decreases and falls below half of the external load current I _i , FIG. As in B, charging of the secondary battery V ₀ starts. Now, the current from each due to the discharge from the first capacitor C ₁ and the second capacitor C ₂ is for the first inductor L ₁ of the current I _L1 is greater than the second inductor L ₁ of the current I _L2 is there.

Next, when the current I _{L1 of} the first inductor L ₁ decreases to zero, FIG. Like C, the current path is in the order of discharging the first capacitor C ₁ , charging the secondary battery V ₀ , discharging the second capacitor C ₂ , the first pole P to the external load, and the second pole N. .
Next, when the current I _{L1 of} the first inductor L ₁ is reversed, FIG. As shown in D, as a current path, the discharging of the _second capacitor C ₂ , the first inductor L ₁ , the charging of the secondary battery V ₀ , the discharging of the first capacitor C ₁ , the secondary battery V ₀ And the second inductor L ₂ increase in this order. At this time, the first inductor L ₁ and the second inductor L ₂ are connected to FIG. A reverse current is generated which is not present in the conventional impedance source inverter 900 of A.

Thus, the first inductor L ₁ of the current I _L1 and the second inductor L ₂ of the current I _L2 is sufficiently small (absolute value in the reverse direction is large) Incidentally, FIG. As in E, the three-phase switching unit S _3ph is set in a short-through state, and at the same time, the switch element Q ₀ is turned off. Then, FIG. A conventional impedance source inverter of FIG. FIG. Although the current became zero as in E, in this embodiment, FIG. Like E, there is a path through which current flows. For this reason, the current changes continuously. At this time, FIG. As in E, the first inductor L ₁ of the current I _L1 direction of the second inductor L ₁ of the current I _L2 is FIG. Although it is in the direction of D, it approaches 0 quickly. This connection state is shown in FIG. Are the same as A, a 3-phase switching unit S _3ph a short through state, if the switching element Q ₀ remains off, the first inductor L ₁ of the current I _L1 second inductor L ₁ of the current After I _L2 becomes 0, FIG. Transition to A state.

FIG. 4 shows the state of the current shown in FIGS. 2 and 3 over time for the current I _L1 of the first inductor L ₁ . In the time axis, FIG. A to 2. E, FIG. A to FIG. It shows which time interval the current state of E corresponds to.
4 and 14. Comparing B, the power conversion circuit 100 according to the present embodiment has a time interval in which the current I _{L1 of} the first inductor L ₁ is 0, which the conventional impedance source inverter 900 has, and is slightly (A time indicated as 3.C). As a result, the potentials of the capacitors C ₁ and C ₂ cannot be controlled, and the potential of the three-phase alternating current that is the output cannot be controlled.

FIG. Two simulations were performed using the power conversion circuit 100 shown in FIG. At this time, since the control is different from that shown in FIG. A to FIG. E and FIG. A to FIG. Different from E. The control of 3-phase switching unit intact, the case where the always off the first bidirectional switch Q _0, was two simulations as well. This will be briefly described with reference to the drawings.

[First simulation of the present invention]
FIG. A is a graph showing a change in the current I _L1 of the first inductor L _{1 as} a first simulation result of the present invention. In this simulation, switching was made in the order of short through / zero vector / active. FIG. A is after reaching steady state.
In the short-through section, see Figure 3. E, FIG. The current state was in the order of A. Next, when the zero vector state (the state shown in FIG. 2.B) was continued, the current I _{L1 of} the first inductor L ₁ was significantly lower than half of the current I _i of the external load. After this, FIG. B to FIG. D through the active state of D and again a short through section. It became the state of E.

[First simulation of comparative example]
FIG. B is a graph showing a change in the current I _L1 of the first inductor L _{1 as} a first simulation result of the comparative example. In this simulation, switching is made in the order of short through / zero vector / active, and the timing is shown in FIG. This is the same as the first simulation of the present invention shown in FIG. In addition, FIG. A case where the first bidirectional switch Q _{0 of A} is always off is shown as this comparative example. The current state is shown in FIG. A thru | or FIG. Let E respond.
In the short-through section, FIG. A current state. Next, when the zero vector state is continued, FIG. After passing through the state of B, FIG. In the state E, that is, the current I _{L1 of} the first inductor L ₁ becomes zero. Thereafter, the active state is entered, and the current I _{L1 of} the first inductor L ₁ gradually increases to reach half of the external load I _i . It became the state of D.

[Second simulation of the present invention]
FIG. A is a graph showing a change in the current I _L1 of the first inductor L _{1 as} a first simulation result of the present invention. In this simulation, switching was performed in the order of short through / active / zero vector. FIG. A is after reaching steady state.
In the short-through section, see Figure 3. E, FIG. The current state was in the order of A. Next, when switching to active, the current state is as shown in FIG. From C to FIG. E and FIG. A, FIG. When the current I _{L1 of} the first inductor L ₁ fell below half of the current I _i of the external load, the zero vector state was switched. The current state at this time is shown in FIG. Although it is different from B, the current I _L1 of the first inductor L ₁ has decreased to 0 and the absolute value has increased in the opposite direction. After this, again in the short-through section, FIG. It became the state of E.

[Second simulation of comparative example]
FIG. B is a graph showing a change in the current I _L1 of the first inductor L _{1 as} a second simulation result of the comparative example. In this simulation, switching is made in the order of short-through / active / zero vector, and the timing is shown in FIG. This is the same as the second simulation of the present invention shown in FIG. In addition, FIG. A case where the first bidirectional switch Q _{0 of A} is always off is shown as this comparative example. The current state is shown in FIG. A thru | or FIG. Use E for correspondence.
In the short-through section, FIG. A current state. Next, the active state is entered, and FIG. From the state of C, the current I _{L1 of} the first inductor L ₁ gradually decreases to reach half of the external load I _i , and FIG. It became the state of D. Next, it switches to the zero vector state, and FIG. After passing through the state of B, FIG. In the state E, that is, the current I _{L1 of} the first inductor L ₁ becomes zero.

In both the first and second simulations of the present invention, the voltage of the _first capacitor C ₁ is always equal to the voltage of the second capacitor C ₂ . It changed like A.
On the other hand, in both the first and second simulations of the comparative example, the voltage of the _first capacitor C ₁ is always equal to the voltage of the second capacitor C ₂ . It changed like B.
As described above, when the power conversion circuit 100 of the present invention is designed for switching control at a setting of 650 kV, if the first bidirectional switch is always turned off and driven, the capacitor voltage is approximately doubled.

  FIG. 8 is a graph showing a simulation result of driving the power conversion circuit 100 according to the present embodiment by the PWM control of the simulation. This shows temporal changes in voltage and current for one terminal of three-phase output, for example, terminal A, and it can be seen that a very accurate sine wave is output.

FIG. A is a circuit diagram showing a configuration of a power conversion circuit 200 according to a second specific example of the present invention. FIG. A power conversion circuit 200 of FIG. In this configuration, a switch element Q ₁ and a diode D ₂ connected in antiparallel to the switch element Q ₂ are added to the power conversion circuit 100 of A.
That is, FIG. Power conversion circuit 200 A is provided between the switching element Q ₀ and the inductor L _1, a switching element Q ₂ to which conducts If on, connected diodes D ₂ is inserted in reverse parallel, the first inductor In parallel with the series connection of L ₁ and the second capacitor C ₂ , the switch element Q ₁ is connected in a direction in which a current flows from the inductor L ₁ to the inductor L ₂ when turned on. The switch element Q ₂ and the switch element Q ₀ are connected in reverse series. The switch element Q ₁ may be a reverse blocking IGBT or a power transistor. Those having a parasitic diode of reverse conduction are not preferable.
FIG. The A power conversion circuit 200 outputs three-phase AC power from the secondary battery V ₀ to, for example, a three-phase induction motor, which is an external load connected to the three terminals A, B, and C, and outputs from the motor. When charging the regenerative current to the secondary battery V ₀ , the DC voltage generated by the regenerative current is boosted. Booster switch circuit responsible for boosting the regenerative current is a switch element Q _1, the switch element Q _2.
FIG. B is shown in FIG. It is the circuit diagram which simplified the power converter circuit 200 of A. When power is supplied to the external load, it can be considered that a constant current source in which a constant current flows from the first pole P to the second pole N is connected. When a regenerative current is input from the outside, it can be considered that a virtual diode D _im and a virtual potential V _im are connected in series between the first pole P and the second pole N. At this time, the negative pole of the virtual diode D _im is connected to the first pole P, and the negative pole of the virtual potential V _im is connected to the second pole N.

FIG. 10 is three circuit diagrams with current paths showing the operation of the power conversion circuit 200 according to the second specific example of the present invention.
FIG. A shows a state in which active power is supplied to, for example, a three-phase induction motor that is an external load. The switch element Q ₁ is always off and the switch element Q ₂ is always on. FIG. In A, the constant current source is between the first pole P and the second pole N, and FIG. C to FIG. Although only the element corresponding to B is shown, the six switch elements of the three-phase switching unit S _3ph and the switch element Q ₀ may be controlled in the same manner as in the first embodiment. That is, FIG. A to FIG. Switching is performed corresponding to the 10 states of E. At this time, FIG. B to FIG. Unless corresponding to the state of E may be off the switching element Q _2.

FIG. B and FIG. C is a circuit diagram showing two current states for charging the secondary battery V ₀ by the regenerative current from the induction motor. In this case, keep and always turn off the switch element Q _2.
First, FIG. As in B, the switch element Q ₀ is turned off and the switch element Q ₁ is turned on. Then, the first inductor L ₁ is charged by the second capacitor C ₂ , and the second inductor L ₂ is charged by the first capacitor C ₁ . At this time, since the potential due to the regenerative current is lower than the potentials of the capacitors C ₁ and C ₂ , the first pole P and the second pole N are disconnected.
Next, FIG. As in C, the switch element Q ₀ is turned on and the switch element Q ₁ is turned off. Then, the sum of the potential of the charged _first inductor L _{1 and} the potential of the second capacitor C ₂ and the sum of the potential of the charged second inductor L _{2 and} the potential of the first capacitor C ₁ are obtained. The secondary battery V ₀ is charged. At this time, the regenerative current is charged to the secondary battery V ₀ via the second inductor L ₂ , the second pole N, the virtual potential V _im , the virtual diode D _im , the first pole P, and the first inductor L _1. The

  Since the regenerative current can be used effectively, the present invention can be used for a vehicle having an electric motor including a hybrid type, an electric vehicle, and the like.

The circuit diagram (1.A) and the simplified circuit diagram (1.B) of the power converter circuit 100 which concern on one specific Example of this invention. 5 is a circuit diagram showing five current states of the power conversion circuit 100. FIG. 5 is a circuit diagram showing five current states of the power conversion circuit 100. FIG. Graph chart showing the change of the first inductor L ₁ of the current I _L1 of the power conversion circuit 100. The graph which shows two simulation results. The graph which shows two simulation results. The graph which shows two simulation results. The graph which shows the time change (waveform) of the voltage of 3 phase alternating current power which the power converter circuit 100 outputs, and an electric current which are simulation results. A circuit diagram (9.A) and a simplified circuit diagram (9.B) of a power conversion circuit 200 according to a second specific example of the present invention. The circuit diagram of 3 sheets which showed the electric current state of the power converter circuit 200. FIG. A circuit diagram (11.A) and a simplified circuit diagram (11.B) of an impedance source inverter 900 according to a conventional example. The graph which shows an example of control of six switches of impedance source inverter 900 5 is a circuit diagram showing five current states of the impedance source inverter 900. FIG. 2 is a graph showing two changes in the current I _L1 of the first inductor L ₁ of the impedance source inverter 900. FIG.

Explanation of symbols

V ₀ : Secondary battery (rechargeable battery)
Q ₀ : Switch element (IGBT) forming the first bidirectional switch
Q ₁ : Switch element (power transistor or reverse blocking IGBT)
Q ₂ : Switch element (IGBT)
D ₀ : Diode that forms a first bidirectional switch D ₂ : Diode that forms a bidirectional switch L ₁ : First inductor L ₂ : Second inductor C ₁ : First capacitor C ₂ : Second Capacitor S _3ph : Three-phase switching circuit P: First pole of the three-phase switching circuit S _3ph (DC high potential side)
N: 2nd pole of the 3-phase switching circuit S _3ph (DC low potential side)
A, B, C: Three-phase AC terminals of the three-phase switching circuit S _3ph Q _ap , Q _bp , Q _cp , Q _an , Q _bn , Q _cn : form the second bidirectional switch of the three-phase switching circuit S _3ph Switch element (IGBT)
D _ap , D _bp , D _cp , D _an , D _bn , D _cn : diodes forming the second bidirectional switch of the three-phase switching circuit S _3ph

Claims (2)

A DC power supply unit having a secondary battery and a first bidirectional switch;
An impedance unit having first and second inductors and first and second capacitors;
A power conversion circuit including at least six second bidirectional switches and a three-phase switching unit having three-phase input / output terminals,
Each of the first and second bidirectional switches includes a transistor that conducts in one direction by a control potential, and a diode connected in reverse parallel thereto.
The impedance part is
A first terminal of the first inductor and a first terminal of the first capacitor are connected to a positive electrode side of the DC power supply unit;
A second terminal of the first inductor and a first terminal of the second capacitor are connected to a first pole side of the three-phase switching unit;
A first terminal of the second inductor and a second terminal of the first capacitor are connected to a second pole side of the three-phase switching unit;
A second terminal of the second inductor and a second terminal of the second capacitor are connected to the negative electrode side of the DC power supply unit;
The three-phase switching unit includes three sets of switch arrays in which two of the six second bidirectional switches are connected in series in the same direction, and are connected in parallel in the same direction. Current flows from the first pole side to the second pole side by controlling the three-phase input / output terminals of the two second bidirectional switches of the three sets of switch rows. Connected to the middle point of
In at least one set of the switch row of the three-phase switching unit, when both of the two second bidirectional switches constituting it are on, the first bidirectional switch is turned off and the second A control device that controls the secondary battery to be dischargeable; otherwise, the first bidirectional switch is turned on to allow a current to flow in the charging direction of the secondary battery. Power conversion circuit. A DC power supply unit having a secondary battery and a first bidirectional switch;
An impedance unit having first and second inductors and first and second capacitors;
A power conversion circuit including at least six second bidirectional switches and a three-phase switching unit having three-phase input / output terminals,
Each of the first and second bidirectional switches includes a transistor that conducts in one direction by a control potential, and a diode connected in reverse parallel thereto.
The impedance part is
A first terminal of the first inductor and a first terminal of the first capacitor are connected to a positive electrode side of the DC power supply unit;
A second terminal of the first inductor and a first terminal of the second capacitor are connected to a first pole side of the three-phase switching unit;
A first terminal of the second inductor and a second terminal of the first capacitor are connected to a second pole side of the three-phase switching unit;
A second terminal of the second inductor and a second terminal of the second capacitor are connected to a negative electrode side of the DC power supply unit;
The three-phase switching unit includes three sets of switch arrays in which two of the six second bidirectional switches are connected in series in the same direction, and are connected in parallel in the same direction. Current flows from the first pole side to the second pole side by controlling the three-phase input / output terminals of the two second bidirectional switches of the three sets of switch rows. Connected to the middle point of
The power conversion circuit further comprises a step-up switch circuit that is controlled to start when the regenerative current is charged to the secondary battery from the input / output terminal of the three-phase switching unit.