JP2006271069A - Parallel multiplex chopper device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent an excessive current from running into a reflux diode of a short-circuited unit chopper having a simple structure, without having to attach a reverse-blocking diode. <P>SOLUTION: This parallel multiplex chopper device is comprised of the plurality of unit choppers the quantity of which is N are connected in parallel, where N is an integer of two or larger. Each of the unit choppers is composed of a switching element 6, which is connected to the positive side of a common DC power supply 11 through an overcurrent cut-off element 5 to supply DC power to a common load 3 by its on-off operation; a diode 7, connected in such a direction that a current runs from the negative side of the DC voltage source to the output side of the switching element; and a current detector 8 attached onto the output side of the switching element. This permits all the switching elements to turn off, when an output current of any of the unit choppers detected by the current detector exceeds a first predetermined value as a negative overcurrent threshold. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a parallel multiple chopper apparatus that supplies DC power to a load by connecting a plurality of unit choppers in parallel to a common DC power source.

  For example, in a chopper configuration device that converts a DC voltage into a desired DC voltage, when supplying a large current with low ripple to a load, a parallel multiple chopper device that shares load current with multiple unit choppers in parallel May be adopted. In this case, a phase difference is generally provided in the switching operation of the main switching element of each unit chopper so as to reduce the output ripple.

  In a normal chopper device that is not in parallel configuration, an overcurrent cutoff element is provided at the input part of the chopper device, and when the free wheel diode provided in parallel on the output side of the main switching element is short-circuited, the overcurrent cutoff element The current that flows in is cut off.

  However, in the case of a parallel multiple chopper device, if the free-wheeling diode of a unit chopper is short-circuited, the free-wheeling diode is short-circuited from another healthy unit chopper connected in parallel even if the input of the unit chopper is cut off. Overcurrent flows into the chopper.

In order to avoid the above situation, reverse blocking diodes are provided in series on the output side of each unit chopper, and the output is connected in parallel, so that the inflow current from other healthy unit choppers when the freewheeling diode is short-circuited Proposals have been made to prevent the unit chopper from being detected (see, for example, Patent Document 1).
JP-A-11-289755 (page 4, FIG. 1)

  The parallel multiple chopper device proposed in Patent Document 1 has a phase difference in the switching operation of the main switching element of each unit chopper, and an abnormality such as a short circuit of a free-wheeling diode in a logic circuit using this phase difference. Detection is in progress. In the parallel multiple chopper device disclosed in Patent Document 1, there is a timing at which only one unit chopper shares the load current instantaneously, and therefore, the current duty per unit chopper circuit may become severe. . Therefore, the capacity of the reverse blocking diode inserted in series with each unit chopper is increased.

  In a parallel multiple chopper device that supplies a large current to the load, a balance reactor may be connected to the output side of the unit chopper to suppress cross current from other unit choppers. Although it is conceivable to suppress overcurrent at the time, in this case, a circuit configuration becomes complicated, for example, a detection circuit is newly required when the reverse blocking diode is short-circuited, and the reliability of the apparatus is lowered.

  Also, as one of the methods not providing the reverse blocking diode, there is a method of detecting the operation of the current blocking element for cutting off the current flowing from the DC power source and stopping the switching operation of the unit chopper when the freewheeling diode is short-circuited. Although it is conceivable, a current interruption element such as a normal fuse generally detects the interruption operation mechanically, and has a problem of response speed.

  The present invention has been made in view of the above, and is a parallel multiplex that has a relatively simple configuration without providing a reverse blocking diode so that an excessive current does not flow into a free-wheeling diode of a short-circuited unit chopper. An object is to provide a chopper device.

  In order to achieve the above object, a parallel multiple chopper device according to a first aspect of the present invention is connected to the positive side of a common DC power source via an overcurrent cutoff element, and DC power is supplied to a common load by its on / off operation. A switching element for supplying the switching element, a diode connected in a direction from the negative side of the DC voltage source to the output side of the switching element, and a current detection means provided on the output side of the switching element. In a parallel multiple chopper device in which unit choppers N (N is an integer of 2 or more) are connected in parallel, the output current of any unit chopper detected by the current detection means is a negative overcurrent threshold value. When a certain first predetermined value is exceeded, all the switching elements are turned off.

  The parallel multiple chopper device according to the second aspect of the present invention is a switching element that is connected to the positive side of a common DC power source via an overcurrent blocking element and supplies DC power to a common load by its on / off operation. A unit chopper N (comprising: a diode connected in a direction of flowing from the negative side of the DC voltage source to the output side of the switching element; and a current detection means provided on the output side of the switching element. N is an integer of 2 or more) In a parallel multiple chopper device in which units are connected in parallel, a value obtained by dividing the sum of output currents of the unit chopper detected by the current detection means by the unit chopper parallel number N and each unit chopper The output currents of the unit choppers are compared to obtain respective deviations, and when the deviation of any of the unit choppers exceeds a third predetermined value, all the switching elements It is characterized in that so as to turn off.

  According to the present invention, it is possible to provide a parallel multiple chopper device in which an excessive current does not flow into a free-wheeling diode of a short-circuited unit chopper with a relatively simple configuration without providing a reverse blocking diode. it can.

  Embodiments of the present invention will be described below with reference to the drawings.

  1 is a block diagram of a parallel multiple chopper device according to a first embodiment of the present invention.

  The N unit choppers 2A, 2B,... 2N connected in parallel to the common DC power source 1 have their outputs connected in parallel and supply desired DC power to the load 3 composed of a resistor and a reactor. ing. In order to obtain this desired DC power, the N unit choppers 2A, 2B,... 2N are controlled by a common control unit 4. The internal configuration of each unit chopper 2A, 2B,... 2N is as follows.

  The DC input supplied from the DC power source 1 is supplied to the switching elements 6A, 6B,..., 6N via the overcurrent cutoff elements 5A, 5B,. On the output side of the switching elements 6A, 6B,..., 6N, free-wheeling diodes 7A, 7B are arranged in the direction of passing from the negative bus of the DC power supply 1 to the output side of the switching elements 6A, 6B,. .., 7N are connected. The outputs of the switching elements 6A, 6B, ..., 6N are connected to the balance reactors 9A, 9B, ..., 9N via the current detection means 8A, 8B, ..., 8N, and the balance reactor 9A, The outputs of 9B,..., 9N are connected in parallel to supply power to the load 3.

  Next, the internal configuration of the common control unit 4 will be described.

  The output current ImA, ImB,..., ImN of each unit chopper detected by the current detection means 8A, 8B,..., 8N is given to the comparators 41A, 41B,. Each is compared with the current threshold. Here, the direction in which a current flows from each unit chopper to the load 3 is positive. The outputs of the comparators 41A, 41B,..., 41N are inputs to the OR circuit 42. Then, the OR circuit 42 applies a gate pulse to a gate pulse generation circuit 43 provided to supply a gate pulse to the switching elements 6A, 6B,..., 6N of each unit chopper based on the command value. The stop command is output.

  The operation and effect of the block configuration of FIG. 1 will be described below.

  When the unit choppers 2A, 2B,..., 2N are operating normally, in order to suppress the current flowing through the free-wheeling diodes 7A, 7B,. 8B,..., 8N do not detect a negative current. However, when any of the free-wheeling diodes 7A, 7B,..., 7N is short-circuited, a short-circuit current flows from the DC power supply 1. This short circuit current is normally interrupted by the current interrupting elements 5A, 5B,... 5N connected to the unit choppers 2A, 2B,. However, in this parallel multiple chopper device, since the load side of each unit chopper is connected in parallel, the impedance of the load 3 from the other unit chopper and the impedance of the balance reactor of the unit chopper are connected to the unit chopper whose short circuit is short-circuited. A short-circuit current having a magnitude determined by the reciprocal ratio of flows in. Therefore, the current detection means 8A, 8B,..., 8N detect the output currents ImA, ImB,. , A stop command is transmitted to the gate pulse generation circuit 43, and the gate pulses applied to all the switching elements 6A, 6B,..., 6N are turned off. If the negative overcurrent threshold is appropriately selected and the control unit 4 is configured so that it can operate quickly, the above-described protective operation causes the return diode to fail from another healthy unit chopper. Current inflow to the unit chopper can be suppressed.

  The balance reactors 9A, 9B,..., 9N are necessary for suppressing the cross current when a phase difference is provided in the ON / OFF control of the unit choppers 2A, 2B,. May be omitted.

  FIG. 2 is a block diagram of a parallel multiple chopper device according to the second embodiment of the present invention. In the second embodiment, the same parts as those in the block configuration diagram of the parallel multiple chopper device according to the first embodiment shown in FIG. The second embodiment differs from the first embodiment in that the output currents ImA, ImB,..., ImN detected by the unit choppers detected by the current detection means 8A, 8B,. Comparators 44A, 44B,..., 44N are provided, and 1 is output when the output currents ImA, ImB,..., ImN of the respective unit choppers exceed a predetermined positive overcurrent threshold. However, this is supplied to the OR circuit 42.

  The output currents ImA, ImB,..., ImN flowing from each unit chopper to the load 3 are detected by the current detection means 8A, 8B,. When detected or when a negative current exceeding the negative overcurrent threshold is detected, the gate commands of all the switching elements 6A, 6B,..., 6N are turned off. With this configuration, a parallel multiple chopper device is provided in which the overcurrent protection operation at the time of abnormality of the load 3 or the like and the overcurrent protection operation at the time of abnormality of the freewheeling diodes 7A, 7B,. Is possible.

  In the second embodiment, (absolute value of positive overcurrent threshold) >> (absolute value of negative overcurrent threshold). This is due to the following reason.

  In a normal parallel multiple chopper device, in normal operation, current flows only in the direction of flowing from the unit chopper to the load, that is, in the positive direction. In this case, assuming that the currents flowing through the unit choppers connected in parallel are balanced, each output current is 1 / N of the load current. Therefore, at least the positive overcurrent threshold needs to be greater than or equal to ILmax / N, where ILmax is the maximum load current.

  On the other hand, since the current in the negative direction flows only when the free-wheeling diodes 7A, 7B,..., 7N are short-circuited, the threshold value for the negative overcurrent is as small as possible without causing unnecessary malfunction due to noise or the like. Set it to a value.

  Hereinafter, a parallel multiple chopper device according to a third embodiment of the present invention will be described with reference to FIGS. FIG. 3 is a block diagram of a parallel multiple chopper device according to the third embodiment of the present invention.

  In the third embodiment, the same parts as those in the block configuration diagram of the parallel multiple chopper device according to the first embodiment shown in FIG. The third embodiment is different from the first embodiment in that the internal configuration of the control unit 4b is changed as follows. That is, the output currents ImA, ImB,..., ImN of each unit chopper detected by the current detection means 8A, 8B,..., 8N are given to the adder 45, and the addition result is 1 / N by the divider 46. And The output of this divider 46 and the output currents ImA, ImB,..., ImN of each unit chopper are respectively compared by absolute value output subtractors 47A, 47B,. The deviation is set as one input of the comparators 41A, 41B,. Then, the maximum value of each deviation in a predetermined period of the steady state is calculated by the maximum value calculation circuit 48, the maximum value is stored in the memory circuit 49, and the output of the memory circuit 49 is stored in the comparator 41A, The other input of 41B,..., 41N is used.

  Operations of the absolute value output subtractors 47A, 47B,..., 47N and the maximum value calculation circuit 48 will be described with reference to FIG. FIG. 4 is a diagram illustrating the operation of the control unit according to the third embodiment. The value indicated by the broken line in FIG. 4 is the average value of the output of the divider 46, that is, the output current. With respect to this average value, the instantaneous values of the output currents ImA, ImB,..., ImN of individual unit choppers are indicated by solid lines. The absolute value of the deviation between the solid line and the broken line is given from the subtractors 47A, 47B,. Then, the maximum value calculation circuit 48 obtains the maximum values ΔIm_Amax, ΔIm_Bmax,. Each of the other inputs.

  As described above, the absolute value of the deviation from the average value of the output currents ImA, ImB,..., ImN of any unit chopper is the maximum value ΔIm_Amax of each of the deviations in a predetermined period of the steady state. , ΔIm_Bmax,..., ΔIm_Nmax, the OR circuit 42 transmits a stop command to the gate pulse generation circuit 43 to turn off the gate pulses applied to all the switching elements 6A, 6B,. .

  In this way, if the deviation from the average value is automatically calculated and the substantial overcurrent threshold is automatically generated according to each unit chopper, according to the variation in the output current of each unit chopper. It is possible to perform reasonable overcurrent protection. In this case, the direction of the detected current may be positive or negative.

  When one of the freewheeling diodes 7A, 7B,..., 7N is short-circuited, the output current of the unit chopper is rapidly attenuated, so that the deviation between the output current detection value and the average value shortens the maximum deviation during normal operation. Over time. Therefore, according to the present embodiment, an abnormal state can be quickly detected before a current in the negative direction flows through the free wheeling diodes 7A, 7B,.

  In this embodiment, in order to prevent the influence of malfunction due to noise or the like, a value obtained by adding a predetermined margin to each maximum value ΔIm_Amax, ΔIm_Bmax,..., ΔIm_Nmax of the deviation detected by the maximum value calculation circuit 48 is set. The data may be stored in the memory circuit 49.

  In this embodiment, the divider 46 is used to obtain 1 / N of the sum of the output currents of the unit choppers. However, without using the divider 46, the output currents of the unit choppers are multiplied by N times. You may comprise so that it may compare with what was done.

  It is obvious that the present invention is effective even if a predetermined set value is given without automatically generating the maximum value of each deviation in the above-mentioned predetermined period, which is an overcurrent threshold.

  Hereinafter, a parallel multiple chopper device according to a fourth embodiment of the present invention will be described with reference to FIGS. FIG. 4 is a block diagram of a parallel multiple chopper device according to the fourth embodiment of the present invention.

  Regarding the respective parts of the fourth embodiment, the same parts as those of the block configuration diagram of the parallel multiple chopper device according to the first embodiment of FIG. The fourth embodiment is different from the first embodiment in that the internal configuration of the control unit 4c is changed as follows. That is, paying attention to the output current ImA among the output currents ImA, ImB,..., ImN of each unit chopper detected by the current detection means 8A, 8B,. , 50AN,... Are input to the absolute value output subtracters 50AB,..., 50AN,. Absolute values of deviations of output currents of all unit choppers are obtained, and this deviation is set as one input of the comparators 41AB,..., 41AN,. Then, the maximum value of each of the deviations in a predetermined period in the steady state is calculated by the maximum value calculation circuit 48a, and this result is stored in the memory circuit 49, and the comparators 41AB,..., 41AN,. The other input.

  The operations of the absolute value output subtracters 50AB, ..., 50AN, ... and the maximum value calculation circuit 48a will be described with reference to FIG. FIG. 6 is a diagram illustrating the operation of the control unit according to the fourth embodiment. As shown in FIG. 6, the absolute value output subtracters 50AB,..., 50AN compare the output current ImA with the output current ImB,. The values ImA_Bmax,..., ImA_Nmax are obtained. Each of these values is stored in the memory circuit 49, and this stored value is used as the other input of the comparators 41AB,.

  In the above description, the reference unit chopper is the unit chopper 2A, and the output current ImA is used as a reference. However, the same applies to the output current ImB of the unit chopper 2B, and other unit choppers may be used as a reference. .

  By configuring as described above, the absolute value of the deviation between the output current of any reference unit chopper and the output currents of all other unit choppers exceeds the maximum value of the deviation in a predetermined period of the steady state. When the OR circuit 42 transmits a stop command to the gate pulse generation circuit 43, it is possible to perform the overcurrent protection operation by turning off the gate pulses applied to all the switching elements 6A, 6B,. Become.

  According to the present embodiment, as in the case of the third embodiment, in addition to being able to quickly detect an abnormal state, the current deviation is detected only by comparing with a comparator or the like. It becomes possible to constitute a parallel multiple chopper device by the combination.

  In the present embodiment, the technique for preventing the influence of malfunction due to noise or the like, and that the overcurrent threshold is effective as a predetermined set value are the same as in the third embodiment.

  FIG. 7 is a block diagram of a parallel multiple chopper device according to the fifth embodiment of the present invention. The same parts as those in the block configuration diagram of the parallel multiple chopper device according to the third embodiment shown in FIG. The fifth embodiment is different from the third embodiment in that the load current detecting means 10 is provided on the input side of the load 3 and the output of the load current detecting means 10 is given to the divider 46 instead of the adder 45. This is the point that the control unit 4d is configured.

  Since the load current is obtained by adding all the output currents ImA, ImB,..., ImN of each unit chopper, the parallel multiple chopper device according to the fifth embodiment has an overcurrent protection effect equivalent to that of the third embodiment. It becomes possible to demonstrate. Further, in the present embodiment, since the load current is detected, it is possible to omit an adding circuit for adding all the output currents of the respective choppers, so that the complexity of the circuit can be avoided.

  In the inventions of the first to fifth embodiments described above, for example, a Hall element is applied to the current detection means for detecting the current of each chopper circuit and the load current detection means for detecting the load current. Thus, detection is preferably performed using detection means insulated from the main circuit of the unit chopper. By using the detection means that is insulated from the main circuit of the unit chopper for each current detection means, it is possible to suppress the influence of noise or the like from propagating to the detection circuit. In general, in a chopper circuit, high di / dt or high dv / dt switching noise is generated by the on / off operation of the switching elements 6A, 6B,. Although the influence of the noise may cause an unnecessary malfunction in the electronic circuit such as the detection circuit, the influence of the noise can be reduced by the current detection means insulated from the main circuit.

The block block diagram of the parallel multiple chopper apparatus which concerns on Example 1 of this invention. The block block diagram of the parallel multiple chopper apparatus which concerns on Example 2 of this invention. The block block diagram of the parallel multiple chopper apparatus which concerns on Example 3 of this invention. FIG. 9 is an operation explanatory diagram of a control unit in Embodiment 3. The block block diagram of the parallel multiple chopper apparatus which concerns on Example 4 of this invention. FIG. 9 is an operation explanatory diagram of a control unit in Embodiment 4. The block block diagram of the parallel multiple chopper apparatus which concerns on Example 5 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 DC power supply 2A, 2B, ..., 2N Unit chopper 3 Load 4, 4a, 4b, 4c, 4d Control part 5A, 5B, ... 5N Overcurrent interruption element 6A, 6B, ..., 6N Switching element 7A Freewheeling diodes 8A, 8B, ..., 8N Current detection means 9A, 9B, ..., 9N Balance reactor 10 Load current detection means 41A, 41B, ..., 41N Comparator 41AB ,..., 41AN Comparator 42 OR circuit 43 Gate pulse generation circuits 44A, 44B,..., 44N Comparator 45 Adder 46 Dividers 47A, 47B,. Circuit 49 Memory circuit 50AB, ..., 50AN Absolute value output subtractor

Claims (8)

A switching element that is connected to the positive side of a common DC power source via an overcurrent cutoff element and supplies DC power to a common load by its on / off operation;
A diode connected in a direction of flowing from the negative side of the DC voltage source to the output side of the switching element;
A parallel multiple chopper device in which unit chopper N (N is an integer of 2 or more) units connected in parallel with current detecting means provided on the output side of the switching element,
The output current of any one of the unit choppers detected by the current detection means is
When a first predetermined value that is a negative overcurrent threshold is exceeded,
A parallel multiple chopper device characterized in that all the switching elements are turned off. The output current of any one of the unit choppers detected by the current detection means is
When a second predetermined value that is a positive overcurrent threshold having an absolute value greater than the absolute value of the first predetermined value is exceeded,
2. The parallel multiple chopper device according to claim 1, wherein all the switching elements are turned off. A switching element that is connected to the positive side of a common DC power source via an overcurrent cutoff element and supplies DC power to a common load by its on / off operation;
A diode connected in a direction of flowing from the negative side of the DC voltage source to the output side of the switching element;
A parallel multiple chopper device in which unit chopper N (N is an integer of 2 or more) units connected in parallel with current detecting means provided on the output side of the switching element,
A value obtained by dividing the total output current of the unit chopper detected by the current detection means by the parallel number N of unit choppers;
The output current of each unit chopper is compared to determine the absolute value of each deviation, and when the absolute value of the deviation of any of the unit choppers exceeds a third predetermined value,
A parallel multiple chopper device characterized in that all the switching elements are turned off. The third predetermined value for each unit chopper is:
The output current of the unit chopper in a predetermined period of the steady operation state,
4. The parallel multiple chopper device according to claim 3, wherein the absolute value of the deviation from a value obtained by dividing the total sum of the output currents by a unit chopper parallel number N is equal to or greater than the maximum value. A switching element that is connected to the positive side of a common DC power source via an overcurrent cutoff element and supplies DC power to a common load by its on / off operation;
A diode connected in a direction of flowing from the negative side of the DC voltage source to the output side of the switching element;
A parallel multiple chopper device in which unit choppers N (N is an integer of 2 or more) units connected in parallel with current detection means provided on the output side of the switching element,
The absolute value of the deviation is obtained by comparing the output current of any one of the unit choppers with the output current of all the unit choppers other than the unit chopper, and the absolute value of the deviation of any one of the unit choppers is the first value. When the predetermined value of 4 is exceeded,
A parallel multiple chopper device characterized in that all the switching elements are turned off. The fourth predetermined value is
An output current of the unit chopper in a predetermined period of a steady operation state;
6. The parallel multiple chopper device according to claim 5, wherein the absolute value of deviations of output currents of all unit choppers other than the unit chopper is equal to or greater than a maximum value. A switching element that is connected to the positive side of a common DC power source via an overcurrent cutoff element and supplies DC power to a common load by its on / off operation;
A diode connected in a direction of flowing from the negative side of the DC voltage source to the output side of the switching element;
A parallel multiple chopper device in which unit choppers N (N is an integer of 2 or more) units connected in parallel with current detection means provided on the output side of the switching element,
A load current detecting means for detecting the load current;
A value obtained by dividing the value detected by the load current detecting means by the unit chopper parallel number N is compared with the output current of the unit chopper detected by each of the current detecting means to obtain respective deviations. When the deviation of the unit chopper exceeds a fifth predetermined value,
A parallel multiple chopper device characterized in that all the switching elements are turned off. The fifth predetermined value for each unit chopper is:
The output current of the unit chopper in a predetermined period of the steady operation state,
8. The parallel multiple chopper device according to claim 7, wherein a value detected by the load current detection means is equal to or greater than a maximum value of a deviation from a value obtained by dividing the value by the unit chopper parallel number N.

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