JP2011114918A - Multi-phase converter circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multi-phase converter circuit which is suppressed in an increase of cost, suppressed in an increase of the number of part items, and high in efficiency. <P>SOLUTION: The circuit is provided with a capacitor between connecting points of respective IGBTs of plurality of boosting converters. The respective IGBTs of the plurality of boosting converters are alternately turned on and off so that currents flowing in reactors of the plurality of boosting converters reach target values, respectively, the IGBT of an upper arm is prohibited from being turned off until limit values of the currents flowing in the respective reactors reach negative values at factoring, and at regeneration, the IGBT of a lower arm is prohibited from being turned off until upper limit values of the currents flowing in the respective reactors reach positive values. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a multiphase converter circuit including a plurality of converters.

FIG. 9 shows a conventional multi-phase converter circuit.
9 includes an output-side capacitor 92 connected in parallel to a load 91, boost converters 94 and 95 provided between a power supply 93 and the capacitor 92, and boost converters 94 and 95, respectively. And a control circuit 96 for controlling the respective operations.

  Boost converter 94 includes IGBTs 97 and 98 connected in series to each other in parallel to capacitor 92, diode 99 connected in antiparallel to IGBT 97, diode 100 connected in antiparallel to IGBT 98, and a connection point of IGBTs 97 and 98. And a power supply 93, and a current sensor 102 that detects a current flowing through the reactor 101.

  Boost converter 95 includes IGBTs 103 and 104 connected in series to each other in parallel to capacitor 92, diode 105 connected in antiparallel to IGBT 103, diode 106 connected in antiparallel to IGBT 104, and a connection point of IGBTs 103 and 104. And a power source 93, and a reactor 107, and a current sensor 108 for detecting a current flowing through the reactor 107.

  The control circuit 96 alternately turns on and off the IGBTs 97 and 98 and turns on and off the IGBTs 103 and 104 alternately so that the total value of the currents flowing through the reactors 101 and 107 becomes the target value Iref. When the IGBT 97 is turned off and the IGBT 98 is turned on, the power from the power source 93 is accumulated in the reactor 101. Next, when the IGBT 97 is turned on and the IGBT 98 is turned off, the voltage applied to the capacitor 92 is increased by the induced electromotive force of the reactor 101. Similarly, when the IGBTs 103 and 104 are alternately turned on and off, the voltage applied to the capacitor 92 increases. By repeating this operation, the voltage of the power supply 93 is boosted to a predetermined voltage corresponding to the target value Iref and output to the load 91.

  In the multiphase converter circuit 90, currents flowing in the circuit can be distributed to the reactor 101 and the reactor 107, respectively, so that loss generated in the reactors 101 and 107 can be reduced.

  However, the multiphase converter circuit 90 has a problem that the switching losses of the IGBTs 97, 98, 103, and 104 are large. For example, as shown in FIG. 10, when the IGBT is turned off, the current flowing through the IGBT does not drop sharply, so that a switching loss occurs. In addition, when the IGBT is turned on, the voltage applied to the IGBT does not drop sharply, resulting in a switching loss.

  Therefore, in order to soft-switch the IGBT, a capacitor is connected in parallel to the IGBT, and a commutation switch is connected to the IGBT via a commutation auxiliary capacitor and a reactor, and the commutation switch is turned on and off to turn on the commutation. There is one that charges and discharges an auxiliary capacitor (see, for example, Patent Document 1 or Patent Document 2).

Japanese Patent Laid-Open No. 2007-028878 JP 2007-228781 A

  However, as described above, a multi-phase converter circuit using a commutation auxiliary capacitor or a commutation switch requires many parts for soft switching, which increases the cost accordingly. .

  Therefore, an object of the present invention is to provide a highly efficient multi-phase converter circuit that suppresses an increase in cost and an increase in the number of parts.

  The multi-phase converter circuit of the present invention includes a first switching element connected in series with each other and connected in parallel with a first capacitor on the output side, and a first anti-parallel connection with the first switching element. A plurality of converters including a diode connected in reverse parallel to the second switching element, and a reactor having one end connected to a connection point of the first and second switching elements, A multi-phase converter circuit in which the other ends of the reactor are connected to each other, a second capacitor provided between connection points of the first and second switching elements in the plurality of boost converters; and the plurality of converters The first and second of each of the plurality of converters so that the currents flowing through the reactors become target values, respectively. In the control mode in which the switching elements are alternately turned on and off, and the total current flowing from each reactor toward the other end of the reactor is positive, the first current flows until the current flowing through each reactor becomes zero or less. In the control mode in which the turn-off of the switching element is prohibited and the total current flowing from each reactor toward the other end of the reactor is negative, the second switching is performed until the current flowing through each reactor becomes zero or more. And a control circuit for prohibiting turn-off of the element.

  The multi-phase converter circuit of the present invention is connected in series with each other, the first and second switching elements connected in parallel with the first capacitor on the output side, and the anti-parallel connection with the first switching element. A plurality of converters including a first diode, a second diode connected in antiparallel to the second switching element, and a reactor having one end connected to a connection point of the first and second switching elements. A multi-phase converter circuit in which the other ends of the reactors are connected to each other, the second capacitor provided in parallel with one or both of the first and second switching elements in the plurality of converters; Each of the plurality of converters is set so that the current flowing through the reactors of the plurality of converters becomes a target value. In the control mode in which the first and second switching elements are alternately turned on and off, and the total current flowing from each reactor toward the other end of the reactor is positive, the current flowing through each reactor is less than zero. In the control mode in which the total current flowing from each reactor toward the other end of the reactor is negative, the current flowing through each reactor becomes zero or more in each control mode. And a control circuit for prohibiting turn-off of the second switching element until it becomes.

  As described above, since the second capacitor is provided, when the total current flowing from each reactor toward the other end of the reactor is positive, when the second switching element is turned off and the dead time is reached, In the control mode in which the total current flowing from each reactor toward the other end of the reactor is negative, the first switching element is turned off and dead. When the time comes, the second capacitor is discharged by the current from the reactor. Also, in the control mode in which the total current flowing from each reactor toward the other end of the reactor is positive, the first switching element is prohibited from being turned off until the current flowing through the reactor becomes zero or less. In the control mode in which the total current flowing toward the end is negative, the turn-off of the second switching element is prohibited until the current flowing through the reactor becomes equal to or greater than zero, and therefore flows from each reactor toward the other end of the reactor. In the control mode in which the total current is positive, when the first switching element is turned off and the dead time is reached, the second capacitor is discharged by the current flowing through the reactor, and the total current flowing from each reactor toward the other end of the reactor When the control mode becomes positive, the second switching element turns off and the dead time Comes to the current flowing through the reactor is the second capacitor is charged flows into the second capacitor. Thus, since the second capacitor is charged / discharged when the switching element is turned off, the rate of increase of the voltage applied to the switching element when the switching element is turned off can be made the same as the charge / discharge speed of the second capacitor. . Thereby, by adjusting the charging / discharging speed of the second capacitor, the voltage rising speed when the switching element is turned off can be suppressed, so that the switching loss when the switching element is turned off can be reduced.

  Further, when the charging of the second capacitor is completed in the dead time after the second switching element is turned off, the voltage applied to the second switching element becomes the same as the output voltage, and the voltage applied to the first switching element becomes zero. Therefore, a current flows through the first diode connected in reverse parallel to the first switching element. Therefore, when the first switching element is turned on, both the voltage applied to the first switching element and the current flowing through the first switching element can be made zero. In addition, when the discharge of the second capacitor is completed during the dead time after the first switching element is turned off, the voltage applied to the second switching element becomes zero, so that the second switching element connected in reverse parallel to the second switching element Current flows through the diode. Therefore, both the voltage applied to the second switching element and the current flowing through the second switching element can be made zero when the second switching element is turned off. As described above, when the switching element is turned on, both the voltage applied to the switching element and the current flowing through the switching element can be made zero, so that the switching loss when the switching element is turned on can be eliminated.

  Therefore, in the multiphase converter circuit of the present invention, the current flowing in the circuit can be distributed to each reactor, so that the loss generated in the reactor can be reduced. Further, as described above, the switching loss when the switching element is turned on and turned off can be reduced. Thereby, each boost converter can be operated with high efficiency.

Moreover, since it is only necessary to provide the second capacitor, an increase in cost can be suppressed.
Further, the control circuit may be configured such that start times of control cycles when the first and second switching elements are alternately turned on and off alternately are shifted from each other in the plurality of converters.

As a result, the ripples of the currents flowing through the reactors cancel each other, so that the ripples of the currents flowing through the power supply and the first capacitor can be reduced.
In addition, when the total current flowing from each reactor toward the other end of the reactor becomes positive, the control circuit causes the first switching element to flow when the current flowing through each reactor becomes less than a negative threshold value. And when the total current flowing from each reactor toward the other end of the reactor becomes negative, the second switching element is turned off when the current flowing through each reactor exceeds a positive threshold value. Let me.

  According to the present invention, an increase in cost can be suppressed and a highly efficient multi-phase converter circuit can be realized.

It is a figure which shows the multiphase converter circuit of embodiment of this invention. It is a figure for demonstrating the operation control at the time of power running and regeneration in the multiphase converter circuit of this embodiment. It is a figure for demonstrating operation | movement of the multiphase converter circuit of this embodiment. It is a figure which shows the timing chart of the voltage in the multiphase converter circuit of this embodiment, or an electric current. It is a figure which shows the switching loss at the time of turn-on or turn-off of IGBT in the multiphase converter circuit of this embodiment. It is a figure which shows the electric current which flows into the reactor and power supply in the multiphase converter circuit of this embodiment. It is a figure which shows the multiphase converter circuit of other embodiment of this invention. It is a figure which shows the multiphase converter circuit of other embodiment of this invention. It is a figure which shows the conventional multiphase converter circuit. It is a figure which shows the switching loss at the time of turn-on or turn-off of IGBT in the conventional multiphase converter circuit.

FIG. 1 is a diagram showing a multiphase converter circuit according to an embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the same component as the structure shown in FIG.
A multi-phase converter circuit 1 shown in FIG. 1 includes an output side capacitor 92 (first capacitor) connected to a load 91, and boost converters 94 and 95 (a plurality of voltage converters) provided between a power source 93 and the capacitor 92, respectively. Converter), capacitor 2 (second capacitor), and control circuit 3 that controls the operation of boost converters 94 and 95.

  Boost converter 94 is connected in series with each other, and IGBT 97 (first switching element) and IGBT 98 (second switching element) connected in parallel to capacitor 92, and diode 99 (first diode) connected in reverse parallel to IGBT 97. ), A diode 100 (second diode) connected in reverse parallel to the IGBT 98, a reactor 101 provided between the connection point of the IGBTs 97 and 98 and the power supply 93, and a current flowing through the reactor 101 (hereinafter referred to as current I1). And a current sensor 102 for detecting

  Boost converter 95 is connected in series with each other, and IGBT 103 (first switching element) and IGBT 104 (second switching element) connected in parallel to capacitor 92, and diode 105 (first diode) connected in reverse parallel to IGBT 103. ), A diode 106 (second diode) connected in reverse parallel to the IGBT 104, a reactor 107 provided between the connection point of the IGBTs 103 and 104 and the power supply 93, and a current flowing through the reactor 107 (hereinafter referred to as current I2). And a current sensor 108 for detecting the

Instead of the IGBT, a bipolar transistor or MOSFET with a diode connected in reverse parallel may be used.
The capacitor 2 is provided between the connection point of the IGBTs 97 and 98 and the connection point of the IGBTs 103 and 104.

  The control circuit 3 includes a control unit 4 that alternately turns on and off the IGBTs 97 and 98 so that the average value of the current I1 is ½ of the target value Iref, and the average value of the current I2 is 1 / of the target value Iref. 2, a control unit 5 that alternately turns on and off the IGBTs 103 and 104 is provided. When the IGBT 97 is turned off and the IGBT 98 is turned on, the power from the power source 93 is accumulated in the reactor 101. Next, when the IGBT 97 is turned on and the IGBT 98 is turned off, the voltage applied to the capacitor 92 is increased by the induced electromotive force of the reactor 101. Similarly, when the IGBTs 103 and 104 are alternately turned on and off, the voltage applied to the capacitor 92 increases. By repeating this operation, the voltage of the power supply 93 is boosted to a predetermined voltage corresponding to the target value Iref and output to the load 91.

  The control units 4 and 5 are respectively an A / D conversion unit 6, amplification units 7 and 8, a subtraction unit 9, a PI control unit 10, a PWM generation unit 11, an inverter 12, and a dead time generation unit 13. , 14, comparators 15 and 16, AND circuits 17 and 18, and OR circuits 19 and 20.

The A / D conversion unit 6 converts the current I1 or the current I2 into a digital value.
The amplifying unit 7 halves the target value Iref input from the outside.
The amplifying unit 8 sets a threshold value Ish (a positive value threshold value) input from the outside to a threshold value −Ish (a negative value threshold value).

The subtraction unit 9 subtracts the output value of the A / D conversion unit 6 from the output value of the amplification unit 7.
The PI control unit 10 performs a PI control calculation on the output value of the subtraction unit 9. For example, the PI control unit 10 calculates a command value such that the output value of the subtraction unit 9 becomes zero, that is, a command value such that the current I1 or the current I2 becomes 1/2 of the target value Iref, and the command The value is output to the PWM generator 11.

  The PWM generator 11 generates a PWM signal based on the command value output from the PI controller 10. For example, the PWM generator 11 compares the command value from the PI controller 10 with a reference triangular wave, and outputs a high level PWM signal when the command value is larger than the reference triangular wave, and the command value is smaller than the reference triangular wave. When a low level PWM signal is output.

The inverter 12 inverts the PWM signal output from the PWM generator 11.
The dead time generation unit 13 provides a predetermined dead time (time when both IGBTs 97 and 98 are turned off or time when both IGBTs 103 and 104 are turned off) in the PWM signal output from the inverter 12. For example, the dead time generation unit 13 delays the rising timing of the inverted signal of the PWM signal output from the inverter 12 for a predetermined time.

  The dead time generation unit 14 provides the predetermined dead time to the PWM signal output from the PWM generation unit 11. For example, the dead time generation unit 14 delays the rising timing of the PWM signal output from the PWM generation unit 11 for a predetermined time.

  The comparator 15 of the control unit 4 outputs a high level signal when the current I1 is larger than the threshold value −Ish, and outputs a low level signal when the current I1 is equal to or less than the threshold value −Ish. The comparator 16 of the control unit 4 outputs a high level signal when the current I1 is smaller than the threshold value Ish, and outputs a low level signal when the current I1 is equal to or greater than the threshold value Ish.

  The comparator 15 of the control unit 5 outputs a high level signal when the current I2 is larger than the threshold value −Ish, and outputs a low level signal when the current I2 is equal to or less than the threshold value −Ish. The comparator 16 of the control unit 5 outputs a high level signal when the current I2 is smaller than the threshold value Ish, and outputs a low level signal when the current I2 is equal to or greater than the threshold value Ish.

  The AND circuit 17 outputs a high level signal when both the output of the comparator 15 and the output of the OR circuit 19 are high level, and when at least one of the output of the comparator 15 and the output of the OR circuit 19 is low level, Outputs a low level signal.

  The AND circuit 18 outputs a high level signal when both the output of the comparator 16 and the output of the OR circuit 20 are high level, and when at least one of the output of the comparator 16 and the output of the OR circuit 20 is low level, Outputs a low level signal.

  The OR circuit 19 of the control unit 4 outputs a high level signal to the gate of the IGBT 97 when at least one of the output of the AND circuit 17 and the PWM signal (inverted signal) output from the dead time generation unit 13 is high level. When both are low, a low level signal is output to the gate of the IGBT 97. The OR circuit 20 of the control unit 4 outputs a high level signal to the gate of the IGBT 98 when at least one of the output of the AND circuit 18 and the PWM signal output from the dead time generation unit 14 is high level. When the signal is also at the low level, a low level signal is output to the gate of the IGBT 98.

  The OR circuit 19 of the control unit 5 outputs a high level signal to the gate of the IGBT 103 when at least one of the output of the AND circuit 17 and the PWM signal (inverted signal) output from the dead time generation unit 13 is high level. When both are low, a low level signal is output to the gate of the IGBT 103. The OR circuit 20 of the control unit 5 outputs a high level signal to the gate of the IGBT 104 when at least one of the output of the AND circuit 18 and the PWM signal output from the dead time generation unit 14 is high level. When the signal is also at a low level, a low level signal is output to the gate of the IGBT 104.

  In other words, the comparator 15, the AND circuit 17, and the OR circuit 19 make the average current flowing through the power supply 93 positive (from the reactors 101 and 107 to the other end of the reactors 101 and 107 (the connection point of the reactors 101 and 107)). In the control mode in which the total current flowing in the current is positive), even if a low-level PWM signal (inverted signal) is output from the dead time generator 13 to the OR circuit 19, the current I1 or the current I2 is less than or equal to the threshold −Ish Until the signal output from the comparator 15 to the AND circuit 17 changes from high level to low level and the signal output from the AND circuit 17 to OR circuit 19 changes from high level to low level. Level signal continues to be output. Therefore, as shown in FIG. 2A, during power running, the turn-off of the IGBT 97 is prohibited until the current I1 becomes equal to or less than the threshold value −Ish. Further, at the time of power running, turn-off of the IGBT 103 is prohibited until the current I2 becomes equal to or less than the threshold value −Ish.

  Further, by the comparator 16, the AND circuit 18, and the OR circuit 20, the regenerative (reactor 101, 107 to the other end of the reactor 101, 107 (the connection point of the reactors 101, 107) from which the average current flowing to the power source 93 becomes negative is directed. In the control mode in which the total current flowing through is negative), even if a low level PWM signal is output from the dead time generator 14 to the OR circuit 20, the current I1 or the current I2 becomes equal to or greater than the threshold value Ish from the comparator 16. The OR circuit 20 outputs a high level signal until the signal output to the AND circuit 18 changes from high level to low level and the signal output from the AND circuit 18 to OR circuit 20 changes from high level to low level. Continue to be. Therefore, as shown in FIG. 2B, at the time of regeneration, the turn-off of the IGBT 98 is prohibited until the current I1 becomes equal to or higher than the threshold value Ish. Further, at the time of regeneration, turn-off of the IGBT 104 is prohibited until the current I2 becomes equal to or greater than the threshold value Ish.

  The A / D converter 6, the amplifiers 7 and 8, the subtractor 9, the PI controller 10, the PWM generator 11, the inverter 12, and the dead time generators 13 and 14 are configured by software, and the comparators 15, 16, The AND circuits 17 and 18 and the OR circuits 19 and 20 may be configured by hardware.

Next, the operation of the multiphase converter circuit 1 of the present embodiment will be described.
FIG. 3A to FIG. 3H are diagrams for explaining the operation of the multiphase converter circuit 1 of the present embodiment. The capacity of the capacitor 2 is set so that the time required for charging and discharging the capacitor 2 is shorter than the dead time of the IGBTs 97 and 98 or the IGBTs 103 and 104. In the initial state, the IGBT 97 is on, the IGBT 98 is off, the IGBT 103 is off, and the IGBT 104 is on. The current I1 is in the negative direction (direction from the connection point of the IGBTs 97 and 98 to the power supply 93), and the current I2 is positive. It is assumed that the current flows in the direction (direction from the power supply 93 to the connection point of the IGBTs 103 and 104), and the capacitors 2 and 92 are charged to Vo [V], respectively. The output voltage of the power supply 93 is Vb [V].

FIG. 4 is a diagram showing an ON / OFF timing chart of each IGBT and a timing chart of voltages and currents of each IGBT and the like during power running.
First, when the current I1 in the negative direction becomes equal to or less than the threshold value −Ish, the signal output from the comparator 15 of the control unit 4 changes from the high level to the low level. Therefore, the signal output from the control unit 4 to the gate of the IGBT 97 changes from the high level to the low level, and the IGBT 97 is turned off. At this time, the IGBT 98 is off, the IBGT 103 is off, and the IGBT 104 is on. Hereinafter, the state after the IGBT 97 is turned off is referred to as “mode 1”. In “mode 1”, as shown in FIG. 3A, the charge accumulated in the positive electrode of the capacitor 2 by the current I1 in the negative direction, that is, the polarity (+, −) in FIG. As shown in FIG. 4, the voltage Vc applied to the capacitor 2 gradually drops completely from Vo to zero as shown in FIG. As the capacitor 2 is discharged, the voltage applied to the IGBT 98 gradually decreases completely from Vo to zero, and the voltage applied to the IGBT 97 gradually increases from zero to Vo. For example, in the conventional multiphase converter circuit 90 shown in FIG. 9, the capacitor 2 is added in order to make the rising speed more gentle as compared to the rising speed of the voltage applied to the IGBT 97 when the IGBT 97 is turned off. As shown in FIG. 5, when the IGBT 97 is turned off, the rate of increase of the voltage applied to the IGBT 97 can be suppressed. As a result, compared to the conventional multiphase converter circuit 90 shown in FIG. 9, the switching loss that occurs when the IGBT 97 is turned off can be reduced. In “mode 1”, when the discharge of the capacitor 2 is completed and the voltage applied to the IGBT 98 becomes zero, a current (current indicated by a broken-line arrow in FIG. 3A) flows through the diode 100.

  Next, when the signal output from the dead time generation unit 14 of the control unit 4 changes from the low level to the high level, the IGBT 98 is turned on. At this time, the IGBT 97 is off, the IGBT 103 is off, and the IGBT 104 is on. Hereinafter, the state after the IGBT 98 is turned on is referred to as “mode 2”. In “mode 2”, even if the IGBT 98 is turned on, since the diode 100 is conductive as shown in FIG. 3B, no current flows immediately into the IGBT 98 as shown in FIG. Further, since the discharge of the capacitor 2 is completed when the IGBT 98 is turned on, the voltage applied to the IGBT 98 is zero as described above. Thereby, as shown in FIG. 5, when the IGBT 98 is turned on, the voltage applied to the IGBT 98 and the current flowing through the IGBT 98 are zero. Therefore, it is possible to prevent the switching loss of the IGBT 98 from occurring when the IGBT 98 is turned on. After the IGBT 98 is turned on, the current flowing through the diode 100 gradually decreases, and when the current I1 changes from the negative direction to the positive direction (direction from the power supply 93 to the connection point of the IGBTs 97 and 98), the current flows to the IGBT 98. Start flowing.

  Next, when the signal output from the dead time generation unit 14 of the control unit 5 changes from the high level to the low level, the IGBT 104 is turned off. At this time, the IGBT 97 is off, the IGBT 98 is on, and the IGBT 103 is off. Hereinafter, the state after the IGBT 104 is turned off is referred to as “mode 3”. In “mode 3”, as shown in FIG. 3C, the electric current I2 in the positive direction accumulates charges having the opposite polarity to the polarity (+, −) of FIG. As shown, the voltage Vc applied to the capacitor 2 gradually decreases from zero to -Vo. The voltage applied to the IGBT 104 gradually increases from zero to Vo by charging the capacitor 2, and the voltage applied to the IGBT 103 gradually decreases completely from Vo to zero. Compared with the rate of increase of the voltage applied to the IGBT 104 when the IGBT 104 is turned off in the conventional multiphase converter circuit 90 shown in FIG. 9, the capacitor 2 is added to make the rate of increase more gradual. As shown, when the IGBT 104 is turned off, the rate of increase in voltage applied to the IGBT 104 can be suppressed. As a result, compared to the conventional multiphase converter circuit 90 shown in FIG. 9, the switching loss that occurs when the IGBT 104 is turned off can be reduced. In “mode 3”, when charging of the capacitor 2 is completed and the voltage applied to the IGBT 103 becomes zero, a current (current indicated by a broken-line arrow in FIG. 3C) flows through the diode 105.

  Next, when the signal output from the dead time generation unit 13 of the control unit 5 changes from the low level to the high level, the IGBT 103 is turned on. At this time, the IGBT 97 is off, the IGBT 98 is on, and the IGBT 104 is off. Hereinafter, the state after the IGBT 103 is turned on is referred to as “mode 4”. In “mode 4”, even if the IGBT 103 is turned on, the diode 105 is conducting as shown in FIG. 3D, so that no current flows immediately into the IGBT 103 as shown in FIG. In addition, since the charging of the capacitor 2 is completed when the IGBT 103 is turned on, the voltage applied to the IGBT 103 is zero as described above. Thereby, as shown in FIG. 5, when the IGBT 103 is turned on, the voltage applied to the IGBT 103 and the current flowing through the IGBT 103 are zero. Therefore, it is possible to prevent the switching loss of the IGBT 103 from occurring when the IGBT 103 is turned on. When the IGBT 103 is on, the current flowing through the diode 105 gradually decreases. When the current I2 changes from the positive direction to the negative direction (from the connection point of the IGBTs 103 and 104 to the power supply 93), Current begins to flow.

  Next, when the current I2 in the negative direction becomes equal to or less than the threshold value −Ish, the signal output from the comparator 15 of the control unit 5 changes from the high level to the low level. Therefore, the signal output from the control unit 5 to the gate of the IGBT 103 changes from the high level to the low level, and the IGBT 103 is turned off. At this time, the IGBT 97 is off, the IBGT 98 is on, and the IGBT 104 is off. Hereinafter, the state after the IGBT 103 is turned off is referred to as “mode 5”. In “mode 5”, as shown in FIG. 3E, the charge accumulated in the negative electrode of the capacitor 2 by the current I2 in the negative direction, that is, the polarity (+, −) in FIG. As shown in FIG. 4, the voltage Vc applied to the capacitor 2 gradually increases completely from -Vo to zero as shown in FIG. As the capacitor 2 is discharged, the voltage applied to the IGBT 104 gradually decreases completely from Vo to zero, and the voltage applied to the IGBT 103 gradually increases from zero to Vo. Compared with the rate of increase of the voltage applied to the IGBT 103 when the IGBT 103 is turned off in the conventional multiphase converter circuit 90 shown in FIG. 9, the capacitor 2 is added to make the rate of increase more gradual. As shown, when the IGBT 103 is turned off, the rate of voltage increase applied to the IGBT 103 can be suppressed. Thereby, compared with the conventional multiphase converter circuit 90 shown in FIG. 9, the switching loss generated at the time of turning off the IGBT 103 can be reduced. In “mode 5”, when the discharge of the capacitor 2 is completed and the voltage applied to the IGBT 104 becomes zero, a current (current indicated by a broken arrow in FIG. 3E) flows through the diode 106.

  Next, when the signal output from the dead time generation unit 14 of the control unit 5 changes from the low level to the high level, the IGBT 104 is turned on. At this time, the IGBT 97 is off, the IGBT 98 is on, and the IGBT 103 is off. Hereinafter, the state after the IGBT 104 is turned on is referred to as “mode 6”. In “mode 6”, even if the IGBT 104 is turned on, the diode 106 is conducting as shown in FIG. 3F, so that no current flows immediately into the IGBT 104 as shown in FIG. Further, since the discharge of the capacitor 2 is completed when the IGBT 104 is turned on, the voltage applied to the IGBT 104 is zero as described above. As a result, as shown in FIG. 5, when the IGBT 104 is turned on, the voltage applied to the IGBT 104 and the current flowing through the IGBT 104 are zero. Therefore, it is possible to prevent the switching loss of the IGBT 104 from occurring when the IGBT 104 is turned on. After the IGBT 104 is turned on, the current flowing through the diode 106 gradually decreases, and when the current I2 changes from the negative direction to the positive direction, the current starts to flow through the IGBT 104.

  Next, when the signal output from the dead time generation unit 14 of the control unit 4 changes from the high level to the low level, the IGBT 98 is turned off. At this time, the IGBT 97 is off, the IGBT 103 is off, and the IGBT 104 is on. Hereinafter, the state after the IGBT 98 is turned off is referred to as “mode 7”. In “mode 7”, as shown in FIG. 3 (g), the charge of the same polarity as the polarity (+, −) of FIG. 3 (g) is accumulated in the capacitor 2 by the positive current I1. As shown, the voltage Vc applied to the capacitor 2 gradually increases from zero to Vo. As the capacitor 2 is charged, the voltage applied to the IGBT 98 gradually increases from zero to Vo, and the voltage applied to the IGBT 97 gradually decreases completely from Vo to zero. Compared with the rate of increase of the voltage applied to the IGBT 98 when the IGBT 98 is turned off in the conventional multiphase converter circuit 90 shown in FIG. 9, the capacitor 2 is added in order to make the rate of increase more gradual. As shown, when the IGBT 98 is turned off, the rate of voltage increase applied to the IGBT 98 can be suppressed. As a result, compared to the conventional multiphase converter circuit 90 shown in FIG. 9, the switching loss that occurs when the IGBT 98 is turned off can be reduced. In “mode 7”, when charging of the capacitor 2 is completed and the voltage applied to the IGBT 97 becomes zero, a current (current indicated by a broken-line arrow in FIG. 3G) flows through the diode 99.

  Next, when the signal output from the dead time generation unit 13 of the control unit 4 changes from the low level to the high level, the IGBT 97 is turned on. At this time, the IGBT 98 is off, the IGBT 103 is off, and the IGBT 104 is on. Hereinafter, the state after the IGBT 97 is turned on is referred to as “mode 8”. In “mode 8”, even if the IGBT 97 is turned on, the diode 99 is conducting as shown in FIG. 3H, so that no current flows immediately into the IGBT 97 as shown in FIG. Further, since the charging of the capacitor 2 is completed when the IGBT 97 is turned on, the voltage applied to the IGBT 97 is zero as described above. Thereby, as shown in FIG. 5, when the IGBT 97 is turned on, the voltage applied to the IGBT 97 and the current flowing through the IGBT 97 are zero. Therefore, the switching loss of the IGBT 97 can be prevented from occurring when the IGBT 97 is turned on. Note that when the IGBT 97 is on, the current flowing through the diode 99 gradually decreases, and when the current I1 changes from the positive direction to the negative direction, the current starts to flow through the IGBT 97.

Then, the mode is again shifted from “mode 8” to “mode 1”, and “mode 1” to “mode 8” are repeated.
Thus, in the multiphase converter circuit 1 of this embodiment, since the electric current which flows in a circuit can be disperse | distributed to the reactors 101 and 107, the loss which generate | occur | produces in the reactors 101 and 107 can be reduced.

  In the multiphase converter circuit 1 of the present embodiment, the ripple component of the current I1 and the current I2 are controlled by shifting the control cycle in which the IGBTs 97 and 98 are turned on and off and the control cycle in which the IGBTs 103 and 104 are turned on and off. Since the ripple components cancel each other, the ripple component of the current Lb flowing through the power supply 93 and the current flowing through the capacitor 92 can be reduced. For example, when the control cycle in which the IGBTs 97 and 98 are turned on and off is shifted by 1/2 with respect to the control cycle in which the IGBTs 103 and 104 are turned on and off, as shown in FIG. 6, the ripple component of the current I1 and the current I2 The ripple components of the current Ib and the ripple component of the current flowing through the capacitor 92 can be reduced most.

  In addition, since the multiphase converter circuit 1 according to the present embodiment includes the capacitor 2, when the IGBT 98 or IGBT 104 of the lower arm is turned off and the dead time is reached during power running, the current I1 or the current I2 flows to the capacitor 2. When the capacitor 2 is charged and, during regeneration, the IGBT 97 or the IGBT 103 of the upper arm is turned off and the dead time is reached, the capacitor 2 is discharged by the current I1 or the current I2. Also, during power running, turn-off of the IGBTs 97 and 103 is prohibited until the lower limit values of the currents I1 and I2 are negative. During regeneration, turn-off of the IGBTs 98 and 104 is prohibited until the upper limit values of the currents I1 and I2 are positive. Therefore, during power running, when the upper arm IGBT 97 or IGBT 103 is turned off and the dead time is reached, the capacitor 2 is discharged by the current I1 or current I2, and during regeneration, when the lower arm IGBT 98 or IGBT 104 is turned off and the dead time is reached. The current I1 or the current I2 flows through the capacitor 2 and the capacitor 2 is charged. Thus, since the capacitor 2 is charged and discharged when the IGBT is turned off, the rate of increase of the voltage applied to the IGBT when the IGBT is turned off can be made the same as the charging and discharging speed of the capacitor 2. Thereby, by adjusting the charge / discharge speed of the capacitor 2, the voltage increase speed at the time of turn-off of the IGBT can be suppressed, so that the switching loss at the time of turn-off of the IGBT can be reduced.

  Further, in the multiphase converter circuit 1 of the present embodiment, when charging of the capacitor 2 is completed in the dead time after the turn-off of the lower arm IGBT 98 or IGBT 104, the voltage applied to the lower arm IGBT 98 or IGBT 104 is the same as the output voltage Vo. Thus, since the voltage applied to the upper arm IGBT 97 or IGBT 103 becomes zero, a current flows through the diode 99 or the diode 105 connected in reverse parallel to the upper arm IGBT 97 or IGBT 103. Therefore, when the upper arm IGBT 97 or IGBT 103 is turned on, both the voltage applied to the upper arm IGBT 97 or IGBT 103 and the current flowing through the upper arm IGBT 97 or IGBT 103 can be made zero. Further, when the discharge of the capacitor 2 ends in the dead time after the turn-off of the IGBT 97 or IGBT 103 of the upper arm, the voltage applied to the IGBT 98 or IGBT 104 of the lower arm becomes zero, so that it is connected in reverse parallel to the IGBT 98 or IGBT 104 of the lower arm. A current flows through the diode 100 or the diode 106. Therefore, when the lower arm IGBT 98 or IGBT 104 is turned on, the voltage applied to the lower arm IGBT 98 or IGBT 104 and the current flowing through the lower arm IGBT 98 or IGBT 104 can both be made zero. In this way, when the IGBT is turned on, both the voltage applied to the IGBT and the current flowing through the IGBT can be made zero, so that the switching loss when the IGBT is turned on can be reduced.

  Therefore, in the multiphase converter circuit 1 of the present embodiment, the loss generated in the reactors 101 and 107 can be reduced, the ripple component of the current Ib and the ripple component of the current flowing in the capacitor 92 can be reduced, and the IGBT is turned on. Since the switching loss during turn-off can be reduced, the boost converters 94 and 95 can be operated with high efficiency.

In addition, since the multiphase converter circuit 1 of the present embodiment includes only the capacitor 2 as an additional component, an increase in the number of components and an increase in cost can be suppressed.
Moreover, in the multiphase converter circuit 1 of this embodiment, since the switching loss of IGBT can be reduced, IGBT can be reduced in size and the cost of the whole circuit can be suppressed.

  In the multiphase converter circuit 1 of the above-described embodiment, the capacitor 2 for reducing the switching loss of the IGBT is provided between the connection point of the IGBTs 97 and 98 and the connection point of the IGBTs 103 and 104. 2 may be connected in parallel to the IGBTs 97, 98, 103, and 104, respectively.

  FIG. 7 is a diagram showing the multiphase converter circuit 1 when the capacitor 2 is connected in parallel to the IGBTs 97, 98, 103, and 104, respectively. In addition, the same code | symbol is attached | subjected to the same component as the component shown in FIG. The operation of the multiphase converter circuit 1 shown in FIG. 7 is the same as the operation of the multiphase converter circuit 1 shown in FIG. Further, the capacitor 2 may be connected in parallel to one of the IGBTs 97 and 98, and the capacitor 2 may be connected in parallel to one of the IGBTs 103 and 104.

  Even with this configuration, as with the multi-phase converter circuit 1 shown in FIG. 1, the switching loss can be reduced and the boost converters 94 and 95 can be operated with high efficiency. In this configuration, the connection point between the IGBTs 97 and 98 and the connection point between the IGBTs 103 and 104 are not connected to each other via the capacitor 2, so that the other boost converter is generated when the IGBT of one boost converter is turned off. It is possible to eliminate an instantaneous lift or drop of the current flowing through the IGBT.

  Moreover, although the multiphase converter circuit 1 of the above-mentioned embodiment is a structure provided with two boost converters, it is good also as a structure provided with three or more. For example, as shown in FIG. 8, the multi-phase converter circuit 1 may be configured with three boost converters. The multiphase converter circuit 1 shown in FIG. 8 further includes a boost converter 109 in addition to the boost converters 94 and 95. Boost converter 109 is connected in series with each other, and IGBT 110 (first switching element) and IGBT 111 (second switching element) connected in parallel to capacitor 92, and diode 112 (first diode) connected in reverse parallel to IGBT 110. ), A diode 113 (second diode) connected in reverse parallel to the IGBT 111, a reactor 114 provided between the connection point of the IGBTs 110 and 111 and the power supply 93, and a current sensor 115 that detects a current flowing through the reactor 114. And is configured. A capacitor 21 is provided between the connection point of the IGBTs 103 and 104 and the connection point of the IGBTs 110 and 111. Capacitor 21 may be provided between the connection point of IGBTs 97 and 98 and the connection point of IGBTs 110 and 111.

  The operation of the multiphase converter circuit 1 shown in FIG. 8 is similar to the operation of the multiphase converter circuit 1 shown in FIGS. 1 and 7, during powering, the current I1 flowing through the reactor 101, the current I2 flowing through the reactor 107, and the reactor The turn-off of the IGBTs 97, 103, and 110 is prohibited until the lower limit value of each of the currents I3 flowing to 114 becomes negative, and the turn-off of the IGBTs 98, 104, and 111 until the upper limit values of the currents I1 to I3 become positive during regeneration. Is prohibited. Thereby, like the multiphase converter circuit 1 shown in FIGS. 1 and 7, the switching loss can be reduced and the boost converters 94, 95, and 109 can be operated with high efficiency.

  The multi-phase converter circuit 1 of the above-described embodiment is configured to adjust the timing for prohibiting the IGBT turn-off using the threshold values Ish and -Ish. However, the timing for prohibiting the IGBT turn-off using the timer is used. You may comprise so that it may adjust.

DESCRIPTION OF SYMBOLS 1 Multiphase converter circuit 2 Capacitor 3 Control circuit 4, 5 Control part 6 A / D conversion part 7, 8 Amplification part 9 Subtraction part 10 PI control part 11 PWM generation part 12 Inverter 13, 14 Dead time generation part 15, 16 Comparator 17, 18 AND circuit 19, 20 OR circuit 21 Capacitor 90 Multiphase converter circuit 91 Load 92 Capacitor 93 Power supply 94, 95, 109 Boost converter 96 Control circuit 97, 98, 103, 104, 110, 111 IGBT
99, 100, 105, 106, 112, 113 Diode 101, 107, 114 Reactor 102, 108, 115 Current sensor

Claims (4)

First and second switching elements connected in series with each other and connected in parallel with the first capacitor on the output side, a first diode connected in antiparallel with the first switching element, and the second switching element A plurality of converters including a second diode connected in reverse parallel to the element and a reactor having one end connected to a connection point of the first and second switching elements, and the other ends of the reactors are connected to each other A multi-phase converter circuit,
A second capacitor provided between connection points of the first and second switching elements in the plurality of converters;
The first and second switching elements of each of the plurality of converters are alternately turned on and off so that the currents flowing through the reactors of the plurality of converters become target values, respectively, and the other end of the reactor from each reactor. In the control mode in which the total current flowing toward the reactor is positive, turn-off of the first switching element is prohibited until the current flowing through each reactor becomes zero or less, and from each reactor to the other end of the reactor. A control circuit that inhibits turn-off of the second switching element until the current flowing through each reactor becomes zero or more in the control mode in which the total current flowing in the direction is negative;
A multi-phase converter circuit comprising: First and second switching elements connected in series with each other and connected in parallel with the first capacitor on the output side, a first diode connected in antiparallel with the first switching element, and the second switching element A plurality of converters including a second diode connected in reverse parallel to the element and a reactor having one end connected to a connection point of the first and second switching elements, and the other ends of the reactors are connected to each other A multi-phase converter circuit,
A second capacitor provided in parallel with one or both of the first and second switching elements in the plurality of converters;
The first and second switching elements of each of the plurality of converters are alternately turned on and off so that the currents flowing through the reactors of the plurality of converters become target values, respectively, and the other end of the reactor from each reactor. In the control mode in which the total current flowing toward the reactor is positive, turn-off of the first switching element is prohibited until the current flowing through each reactor becomes zero or less, and from each reactor to the other end of the reactor. A control circuit that inhibits turn-off of the second switching element until the current flowing through each reactor becomes zero or more in the control mode in which the total current flowing in the direction is negative;
A multi-phase converter circuit comprising: A multi-phase converter circuit according to claim 1 or 2,
The multi-phase converter circuit, wherein the control circuit shifts a start time of a control cycle when the first and second switching elements are alternately turned on and off one by one in the plurality of converters. The multiphase converter circuit according to any one of claims 1 to 3,
When the total current flowing from each reactor toward the other end of the reactor becomes positive, the control circuit turns off the first switching element when the current flowing through each reactor becomes less than a negative threshold value. And when the total current flowing from each reactor toward the other end of the reactor becomes negative, the second switching element is turned off when the current flowing through each reactor exceeds a positive threshold value. A multi-phase converter circuit.