JP2009296774A - Converter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a converter with a plurality of arrays of switching elements connected in parallel, which improves controllability in a low output region by switching the number of parallel arrays in an output region where current ripples zero-cross to prevent zero cross of the current ripples in low output. <P>SOLUTION: The converter includes: a plurality of arrays of switching elements connected in parallel between a low voltage side and a high voltage side; a plurality of reactors whose one ends are connected to the plurality of arrays of switching elements, respectively, and the other ends are connected in common to the low voltage side; and a capacitor connected in parallel to the output side, and the converter switches the plurality of arrays of switching elements while shifting phase, thereby moving energy between the low voltage side and the high voltage side. Specifically, the converter includes a current detection means for detecting a current value on the input side, and a controller for performing switching control of the number (n) of the plurality of parallel arrays of the plurality of switching elements on the basis of the current value of the input side and the calculated value of current ripples of the input side. With this configuration, the zero cross of the current ripples is prevented in low output. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a converter device that performs step-up or step-down by performing switching control by connecting a plurality of rows of switching elements in parallel between a low-voltage side and a high-voltage side.

  As an example of a converter device, in a buck-boost converter device that functions at a boost ratio m times, a chopper circuit having an integer multiple N that is the closest to m is connected in parallel, and the current phase of each chopper circuit in each column is 2π / It is known that current ripple can be reduced by performing phase control shifted by N (rad) (see, for example, Patent Document 1).

  Patent Document 1 also discloses parallel number switching control (multiphase control) of chopper circuits of N rows (N phases). That is, for a load whose boost ratio fluctuates by 2 times, 3 times, and 6 times, the chopper circuit is configured in 6 parallel, and the current is controlled by switching the parallel number (number of phases) to an integer multiple close to the boost ratio. It is intended to reduce ripple.

  However, in the parallel number switching control (multi-phase multiplex control) of Patent Document 1, the voltage on the high voltage side is controlled with respect to the voltage fluctuation on the low voltage side, and control performance in the low output region is not considered. . That is, as the N number increases, the input current to each chopper circuit decreases. Then, the current ripple waveform of each phase zero-crosses in the low output region, and as a result, the current waveform is distorted in the low output region and the control becomes unstable, and the current ripple reduction effect expected at the beginning of the design can be obtained. There is a problem that it is not possible.

JP2004-357388

  An object of the present invention is to prevent zero crossing of current ripple at low output by switching the parallel number in an output region where current ripple is zero crossing in a converter device configured by connecting converters by switching elements in parallel in a plurality of rows. In particular, the controllability in the low output region can be improved.

  Another object of the present invention is to make it possible to widen an output region in which a current ripple reduction effect expected at the beginning of design can be obtained.

  The present invention relates to a plurality of rows of switching elements connected in parallel between a low voltage side and a high voltage side, and a plurality of reactors having one end connected to the plurality of rows of switching elements and the other end commonly connected to the low voltage side. And a converter device including a capacitor connected in parallel on the output side, and transferring energy between the low voltage side and the high voltage side by switching the plurality of rows of switching elements out of phase. A current detecting means for detecting a current value on the input side, and a control device for performing switching control of the parallel number n of the switching elements in the plurality of columns based on the current value on the input side and the calculated value of the current ripple on the input side Is provided to prevent zero crossing of current ripple at low output.

  The converter device according to the present invention further includes voltage detection means for detecting a voltage value on the input side, so that the control device includes a current ripple on the input side including a voltage value on the input side and a switching frequency in advance. Calculate based on a defined formula.

  In the converter device according to the present invention, the control device further includes a storage device that stores a map diagram showing a correspondence relationship between the input-side current value and the parallel number n, which is created in advance. The parallel number n can be determined with reference to the map diagram based on the current value on the input side detected by the means.

According to the converter device of the present invention, the control device determines whether or not the parallel number n satisfies the following expression using the calculated value ΔIn of the current ripple and the current value Iin on the input side. Done
n ≦ 2Iin / ΔIn
If the above equation is satisfied, the process returns to the recalculation of the current ripple. If the above equation is not satisfied, the decimal number in the calculated value on the right side of the above equation is rounded down to determine an integer number as the parallel number n. be able to.

  Note that the control device may perform switching of the parallel number n by giving a control signal for switching only to the switching elements in the column to be switched.

  According to the converter device of the present invention, by performing switching control of the parallel number of the switching elements in a plurality of columns based on the current value on the input side and the calculated value of the current ripple on the input side, the current ripple at the time of low output can be reduced. Zero crossing can be prevented, controllability can be stabilized, and the current ripple reduction effect expected at the beginning of design can be obtained.

  FIG. 1 shows a configuration of a buck-boost converter device according to a first embodiment of the present invention. Hereinafter, a description will be given assuming that it functions as a boost converter device.

  The converter apparatus includes a DC power supply 11, reactors 21, 22,..., 2S, S columns (switching elements) 31, 32,. 4S, a pair of diodes 41, 42,..., 4S connected in parallel to each power device in a pair, a capacitor 51 connected to the output side common to each column, and a current current sensor CT, and a DC power supply 11 Current detection circuit 61 for detecting the current of the current as input current Iin, voltage detection circuit 62 for detecting the voltage of DC power supply 11, voltage detection circuit 63 for detecting output voltage and output current connected to the device output side, and current detection circuit 64 (including current current sensor CT) and control device 71.

  The reactors 21 to 2S in the S row correspond to the power devices 31 to 3S forming a pair in the S row, one end side is commonly connected to the output side of the DC power supply 11, and the other end side is between the pair of power devices in the corresponding row. Connected to the connection line. The control device 71 receives the detection signals from the current detection circuits 61 and 64 and the voltage detection circuits 62 and 63, respectively, and performs the switching control operation of the power devices 31, 32,.

  As described above, in this converter device, the power devices 31 to 3S forming a pair of S columns connected in parallel are sequentially phase-controlled by the control device 71 with a current phase shifted by 2π / S, whereby the diode 41 It operates as a converter (or chopper circuit) together with ~ 4S. The order of the phase control is not necessarily limited to the order of 31, 32,. This is because, for example, when S = 5, the power devices adjacent in position do not continue to be turned on, such as the first column-third column-fifth column-second column-fourth column-first column. This is because the heat dissipation effect of the power device can be improved.

  FIG. 2 shows waveforms of currents input to each column of S columns. As shown in FIG. 2, the waveform of the input current Ib flowing in each column is formed by a current Iin_nd that is a DC (direct current) component and a current ripple ΔIn that is an AC (alternating current) component. When the relationship of the following formula (1) is established between the DC component current Iin_nd and the AC component current ripple ΔIn, the input current waveform crosses zero.

Iin_nd <ΔIn / 2 (1)
Therefore, the condition that the input current waveform does not cross zero is expressed by the following equation (2).

Iin_nd ≧ ΔIn / 2 (2)
In the converter device according to the first embodiment, the control device 71 has a function as an arithmetic device, and in order to satisfy the condition of the expression (2), the parallel number n of power devices connected to the DC power source 11 (provided that Control is performed so that n ≦ S) is switched under the condition of the following expression (3).

n ≦ 2Iin / ΔIn (3)
However, in Expression (3), Iin is a current value (A) before being input from the DC power supply 11 to the reactors 21 to 2S in the S row, as described above, and is detected by the current detection circuit 61.

  Said parallel number switching control can be performed by the method 1-1 or 1-2 demonstrated below.

  1-1. In advance, the AC component current ripple ΔIn is calculated by the following equation (4), and a map of the input current Iin satisfying the condition of the equation (3) in each parallel number is created and controlled as shown in FIG. The data is stored in a storage device in the device 71. The control device 71 determines the parallel number n corresponding to the input current Iin detected by the current detection circuit 61 with reference to the map diagram.

ΔIn = (Vin · Duty) / (Ln · fs) (4)
However, in Expression (4), Vin is the voltage (V) of the DC power supply 11 detected by the voltage detection circuit 62, Duty is the duty ratio of on / off of the power device, and Ln is the inductance (H) of the reactor in each column. , Fs is a carrier frequency (switching frequency) (Hz).

  1-2. The input current Iin is detected by the current detection circuit 61 of FIG. 1 and the voltage Vin is detected by the voltage detection circuit 62, and the control device 71 performs the calculation of equation (4). When the operating parallel number n does not satisfy the condition of Expression (3), the parallel number n is determined as an integer (decimal numbers are rounded down) on the right side of Expression (3).

  FIG. 4 is a flowchart for explaining the switching control of the parallel number n performed by the control device 71 by the above method 1-2, and the flow of the operation will be briefly described below.

  In FIG. 4, when the parallel number switching control is started, the input current Iin and the input voltage Vin are detected (step S1). The control device 71 calculates the AC component current ripple ΔIn using the equation (4) (step S2). Subsequently, in step S3, it is determined whether or not the condition of the expression (3) is satisfied for the detected input current Iin and the calculated AC component current ripple ΔIn. If the condition of equation (3) is not satisfied, the process returns to step S2 to recalculate the AC component current ripple ΔIn. If the condition of Expression (3) is satisfied, in Step S4, the parallel number n that becomes an integer on the right side of Expression (3) (decimal numbers are rounded down) is determined. In step S5, the power devices 31 to 3S are controlled so that the determined parallel number n is reached. In step S6, it is determined whether or not the switching control of the parallel number n is terminated. If Yes, the parallel number switching control is terminated, and if No, the process returns to step S2.

  Switching of the parallel number n is performed using the following method.

  The control device 71 switches the parallel number n by giving a command to perform the switching operation only to the parallel number of power devices satisfying the above-described formula (3).

  In the above method, it is desirable that the parallel number switching control is performed at the time when the switching of the power devices in the last column of the current parallel number is completed. Of course, the last column in this case does not mean the fifth column, for example, when the current parallel number is five, but is the column where the switching operation is finally performed.

  As described above, the case where the present invention is caused to function as a boost converter device has been described. However, the converter device can also operate as a step-down converter. In this case, a high voltage power source is connected to the two terminals on the capacitor 51 side shown in FIG. The parallel number switching control operation for the power devices 31 to 3S is the same as that in the above-described embodiment, and a stepped-down voltage is obtained on the output side, that is, the portion corresponding to the DC power supply 11 in FIG. The input voltage and the input current are detected by the voltage detection circuit 63 and the current detection circuit 64, respectively.

  According to the converter device according to the above embodiment, by switching the parallel number n so as to satisfy the condition of Expression (2), the zero ripple of the current ripple at the time of low output is prevented, the controllability is stabilized, and the initial design The effect of reducing the current ripple expected in FIG. In particular, by applying this parallel number switching control to battery-driven devices and battery-powered vehicles that have a continuous rating in the low output region, the controllability at low output is stabilized and the current ripple is reduced, resulting in a loss of capacitors. Can be saved, and energy can be saved by improving efficiency.

  The present invention can be applied not only to a buck-boost converter device but also to a boost converter device or a buck converter device, and is suitable for application to a battery drive device or a battery drive vehicle.

FIG. 1 is a circuit configuration diagram showing an embodiment when a converter device according to the present invention is used as a boost converter device. FIG. 2 is a diagram showing a current waveform input to each column in the S column of FIG. FIG. 3 is a map diagram showing the correspondence between the input current Iin and the parallel number n used in the parallel number switching control according to the present invention. FIG. 4 is a flowchart for explaining an example of the parallel number switching control according to the present invention.

Explanation of symbols

11 DC power supply 21 to 2S reactor 31 to 3S paired power device 41 to 4S paired diode

Claims (5)

A plurality of switching elements connected in parallel between the low-voltage side and the high-pressure side; a plurality of reactors having one end connected to the plurality of switching elements and the other end commonly connected to the low-pressure side; and an output side A plurality of rows of switching elements including a capacitor connected in parallel, and a converter device that transfers energy between the low-voltage side and the high-voltage side by switching the phase-shifted elements,
Current detection means for detecting the current value on the input side;
By providing a control device that performs switching control of the parallel number n of the plurality of rows of switching elements based on the current value on the input side and the calculated value of the current ripple on the input side, zero crossing of the current ripple at low output can be achieved. The converter apparatus characterized by preventing. Furthermore, a voltage detection means for detecting the voltage value on the input side is provided,
The converter device according to claim 1, wherein the control device calculates the current ripple on the input side based on a predetermined formula including a voltage value and a switching frequency on the input side. Furthermore, a storage device storing a map diagram showing a correspondence relationship between the current value on the input side and the parallel number n created in advance is provided,
3. The converter according to claim 1, wherein the control device determines the parallel number n with reference to the map diagram based on a current value on the input side detected by the current detection unit. 4. apparatus. The control device determines whether or not the parallel number n satisfies the following expression using the calculated value ΔIn of the current ripple and the current value Iin on the input side:
n ≦ 2Iin / ΔIn
If the above equation is satisfied, the process returns to the recalculation of the current ripple. If the above equation is not satisfied, the decimal number in the calculated value on the right side of the above equation is rounded down to determine an integer number as the parallel number n. The converter device according to claim 1 or 2, wherein   The said control apparatus performs switching of the said parallel number n by giving the control signal for switching only to the switching element of the row | line | column which should be switched, The any one of Claims 1-4 characterized by the above-mentioned. Converter device.

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