JP2013046431A - Chopper device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chopper device that reconciles improved control responsiveness and suppressed energy loss and heat generation of switching elements.SOLUTION: At least one of a plurality of chopper sections 10A, 10B serves as a high carrier frequency chopper section 10B set at a higher carrier frequency than the other chopper section 10A, and the high carrier frequency chopper section 10B is set at a shorter control period than the other chopper section 10A. The other chopper section 10A outputs a current forming a stationary component of a current command value I, and the high carrier frequency chopper section 10B outputs a deviation current Ibetween the current command value Ifor the chopper device and the current from the other chopper section 10A.

Description

  The present invention relates to a chopper device, and more particularly to a chopper device that is required to respond to a sudden change in load current at high speed.

  In recent years, in a chopper device, improvement in responsiveness in control has been demanded. As a technique for obtaining high responsiveness in a chopper device, a method is known in which the frequency of a triangular wave carrier signal (that is, the carrier frequency) to be compared with a sine wave signal having a frequency according to a command is set high.

  However, setting the carrier frequency high causes problems such as increased energy loss and heat generation in the switching element. The upper limit of the carrier frequency is determined by the main circuit constant and element specification.

  In the inverter, Patent Document 1 discloses a device that solves the above problem by switching the carrier frequency in accordance with the load state.

  Also in the chopper device, Patent Document 2 discloses a method of switching the carrier frequency according to the load state.

JP 2006-217776 A (paragraphs [0008] to [0018], FIG. 1) JP 2006-158109 A (paragraphs [0024] to [0033], FIG. 1) Japanese Patent Laid-Open No. 08-228475

However, when switching the carrier frequency according to the load state as described in Patent Documents 1 and 2, the carrier frequency is set high to improve the response in control, or the carrier frequency is set low to reduce the energy loss of the switching element. It is possible to prioritize either one of suppression of heat generation and heat generation, but it has not been possible to simultaneously achieve improvement in control response and suppression of energy loss and heat generation of the switching element.

  As described above, it is an object to provide a chopper device that achieves both improvement in response in control and suppression of energy loss and heat generation of the switching element.

  The present invention has been devised in view of the above-described conventional problems, and one aspect thereof is a chopper device in which a plurality of chopper units that step down or step up a DC voltage are connected in parallel by controlling on / off of a switching element. And at least one of the plurality of chopper units is a high carrier frequency chopper unit set at a higher carrier frequency than the other chopper units, and the control period of the high carrier frequency chopper unit is set to the other chopper unit. The current is a steady component of the current command value from the other chopper unit, and the current instruction value of the chopper device and the other chopper device are set by the high carrier frequency chopper unit. A deviation current from the current is output.

  As another aspect, the two chopper units are connected in parallel, and the control unit that outputs a gate signal to the switching element performs voltage control based on a deviation between the voltage command value and the output voltage detection value of the chopper device. A voltage control unit that outputs a current command value, a low-pass filter that extracts a first current command value that is a stationary component of the current command value, the first current command value, and the high carrier frequency chopper unit The first carrier current control unit that performs current control based on the deviation between the current detection value of the low carrier frequency chopper unit in which a low carrier frequency is set and the low carrier frequency compared to the high carrier frequency chopper unit. A first carrier signal that compares the set carrier signal with the output of the first current controller and outputs a gate signal to the switching element of the low carrier frequency chopper unit. An M signal generation unit, and a second current control unit that performs current control based on a deviation between the difference between the current command value and the current detection value of the low carrier frequency chopper unit and the current detection value of the high carrier frequency chopper unit And a second PWM that compares a carrier signal with a higher carrier frequency compared with the low carrier frequency chopper unit and an output of the second current control unit and outputs a gate signal to the switching element of the high carrier frequency chopper unit. And a signal generation unit.

  As another aspect, the two chopper units are connected in parallel, and the control unit that outputs a gate signal to the switching element performs voltage control based on a deviation between the voltage command value and the output voltage detection value of the chopper device. A voltage control unit that outputs a current command value, a low-pass filter that extracts a first current command value that is a stationary component of the current command value, the first current command value, and the high carrier frequency chopper unit The first carrier current control unit that performs current control based on the deviation between the current detection value of the low carrier frequency chopper unit in which a low carrier frequency is set and the low carrier frequency compared to the high carrier frequency chopper unit. First PWM that compares the set carrier signal with the output of the first current control unit and outputs a gate signal to the switching element of the low carrier frequency chopper unit A signal generator, a second current controller that performs current control based on a difference between the difference between the current command value and the first current command value, and a current detection value of the high carrier frequency chopper unit, and a low carrier frequency chopper A second PWM signal generation unit that compares a carrier signal having a higher carrier frequency compared to the unit and an output of the second current control unit and outputs a gate signal to a switching element of the high carrier frequency chopper unit, It is characterized by having.

  The chopper unit includes a switching module having two switching elements connected in series, and two diodes connected in antiparallel to each of the switching elements, and an intermediate connection point between the two switching elements. And a reactor having one end connected to each other.

  According to the present invention, it is possible to provide a chopper device that achieves both improved response in control and suppression of energy loss and heat generation of the switching element.

It is a block diagram which shows the main circuit of the chopper apparatus in Embodiment 1. FIG. 3 is a configuration diagram illustrating a control unit of the chopper device according to the first embodiment. It is a graph which shows the voltage current waveform at the time of the load current sudden change of the chopper apparatus in Embodiment 1. It is a block diagram which shows the control part of the chopper apparatus in Embodiment 2.

[Embodiment 1]
A chopper device according to the first embodiment will be described with reference to FIGS. FIG. 1 shows a main circuit of the chopper device, and FIG. 2 shows a control unit of the chopper device.

  As shown in FIG. 1, the main circuit of the chopper device according to the first embodiment includes a DC power source 13, a low carrier frequency chopper unit 10 </ b> A, a high carrier frequency chopper unit 10 </ b> B, a capacitor C, and a load 15.

  The low carrier frequency chopper unit 10A and the high carrier frequency chopper unit 10B are connected in parallel, and have a first switching module 11, a second switching module 12, a first reactor DCL1, and a second reactor DCL2. Yes.

   The first switching module 11 includes switching elements S1 and S2 and diodes D1 and D2 connected in antiparallel to the switching elements S1 and S2. One end of the first reactor DCL1 is connected to an intermediate connection point between the switching elements S1, S2 and the diodes D1, D2. The other end of the first reactor DCL1 is connected to the second reactor DCL2, the capacitor C, and the load 15.

   Similarly, the second switching module 12 includes switching elements S3 and S4 and diodes D3 and D4 connected in antiparallel to the switching elements S3 and S4. One end of the second reactor DCL2 is connected to an intermediate connection point between the switching elements S3, S4 and the diodes D3, D4. The other end of the second reactor DCL2 is connected to the first reactor DCL1, the capacitor C, and the load 15.

   The switching elements S1 to S4 shown in FIG. 1 are IGBTs, but this is not limited to IGBTs, and any self-extinguishing switching elements such as GTOs and FETs may be used, and the first switching module 11 and the second switching module 12 need not use the same type of switching element.

  In the chopper device configured as described above, the DC voltage of the DC power supply 13 is stepped down at the switching elements S1 and S3 by turning on and off the switching elements S1 and S3, and the first reactor DCL1 and the second reactor DCL2 are passed through. To charge the capacitor C.

Here, when the switching elements S1 and S3 are turned on, currents flowing through the first and second reactors DCL1 and DCL2 (output currents of the low carrier frequency chopper unit 10A and the high carrier frequency chopper unit 10B) I ₁ and I ₂ are switched to the switching elements. It flows through the path of S1, S3 → first reactor DCL1, second reactor DCL2 → capacitor C, and capacitor C is charged.

Next, when switching elements S1 and S3 are turned off, currents flowing through first and second reactors DCL1 and DCL2 (output currents of low carrier frequency chopper unit 10A and high carrier frequency chopper unit 10B) I ₁ and I ₂ are capacitors C → It flows as a circulating current through the path of the diodes D2 and D4 → the first reactor DCL1 and the second reactor DCL2, and the capacitor C is charged with the residual energy of the first reactor DCL1 and the second reactor DCL2.

   Further, the electrostatic energy of the capacitor C is discharged and regenerated to the DC power source 13 by controlling the switching elements S2 and S4 on and off.

  First, by turning on the switching elements S2 and S4, the electrostatic energy of the capacitor C is discharged through the first reactor DCL1 and the second reactor DCL2 and the switching elements S2 and S4, and the energy at this time is the first energy. Accumulated in reactor DCL1 and second reactor DCL2.

   Next, when the switching elements S2 and S4 are turned off, a voltage due to the counter electromotive force is generated in the first reactor DCL1 and the second reactor DCL2, and the voltage of the capacitor C and the counter electromotive force of the first reactor DCL1 and the second reactor DCL2 are generated. Are added to the DC power supply 13 via the diodes D1 and D3, and the boost chopper is operated.

  Here, the control unit 20 of the chopper device according to the first embodiment will be described with reference to FIG.

  The control unit 20 includes a voltage control unit 21, a low-pass filter 22, a first current control unit 23, a second current control unit 24, a first PWM signal generation unit 25, a second PWM signal generation unit 26, a first carrier generation unit 27, a first A two-carrier generation unit.

First, the voltage control unit (AVR: Automatic Voltage Regulator) 21 performs voltage control using a deviation between the voltage command value V _ref ^* and the output voltage detection value V _out of the chopper device, thereby detecting the output voltage detection value of the chopper device. Control is performed so that _Vout becomes the voltage command value _Vref ^* . The output of the voltage control unit 21 is a current command value I _ref ^* .

This current command value I _ref ^* is a total command value of currents flowing through the two reactors, the first reactor DCL1 and the second reactor DCL2.

In the first embodiment, most of the current command value I _ref ^* is supplied by the output current I ₁ of the low carrier frequency chopper unit 10A flowing through the first reactor DCL1. Therefore, a value obtained by filtering the current command value I _ref ^* with a low pass filter (LPF: Low Pass Filter) 22 and extracting a steady component is set as a first current command value I _1ref ^* .

As a result, the first current command value I _1ref ^* becomes I _1ref ^* = I _ref ^* when the current command value I _ref ^* is steady or only the low-pass filter 22 passing component. When there is a component that does not pass through the low-pass filter 22 (at the time of sudden load change), I _1ref ^* = I _ref ^* is not _satisfied . This is to prevent the overshoot of the first current detection value I _{1 from} becoming too large due to a sudden change in the current command value I _ref ^* .

The first current command value I _1ref ^* and the current detection value I ₁ of the low carrier frequency chopper unit 10A are input to a first current control unit (ACR) 23, and the low carrier frequency chopper unit 10A of the low carrier frequency chopper unit 10A is based on the deviation. Control is performed so that the output current I ₁ becomes the first current command value I _1ref ^* .

A first PWM signal generation unit (PWM: Pulse Width Modulation) 25 generates a PWM waveform by comparing the triangular wave carrier signal of frequency F ₁ generated by the first carrier generation unit 27 with the output of the first current control unit 23. Then, the gate signal G ₁ is output to the first switching module 11.

Further, a difference between the current command value I _ref ^* and the current detection value I ₁ of the low carrier frequency chopper unit 10A is set as a second current command value I _2ref ^* . Thereby, among the current command value I _ref ^*, a current that cannot be supplied by the output current I ₁ of the low carrier frequency chopper unit 10A can be compensated by the output current I ₂ of the high carrier frequency chopper unit 10B.

That is, the first current command value I _1ref ^* is I _1ref ^* = I _ref ^* when the current command value I _ref ^* is only a steady component (passing through the low-pass filter 22), but passes through the low-pass filter 22. When there is a component that does not (when the load suddenly changes), I _1ref ^* = I _ref ^* is not _satisfied . The difference between the first current command value I _1ref ^* and the current command value I _ref ^* is the second current command value I _2ref ^* .

The second current command value I _2ref ^* and the current detection value I ₂ of the high carrier frequency chopper unit 10B are input to the current control unit 24, and the current detection value I ₂ output from the high carrier frequency chopper unit 10B based on the deviation is obtained. The second current command value I _2ref ^* is controlled.

The second PWM signal generation unit 26 compares the triangular wave carrier signal having the frequency F ₂ generated by the second carrier generation unit 28 with the output of the second current control unit 24 to generate a PWM waveform, and the second switching module 12. Outputs a gate signal G2.

Here, the carrier frequencies F ₁ and F ₂ generated in the first and second carrier generation units 27 and 28 are set so as to satisfy the relationship of F ₁ <F ₂ . Further, the first current control unit 23 controls the carrier frequency F ₁ and the second current control unit 24 controls the carrier frequency F ₂ in a synchronized control cycle.

   As a result, the second switching module 12 has a shorter carrier period and control period than the first switching module 11, and a highly responsive control performance can be obtained.

FIG. 3 is a graph showing a voltage-current waveform when the load current suddenly changes in the chopper device according to the first embodiment. As shown in FIG. 3, until the load current suddenly changes, the detected current value I ₁ of the low carrier frequency chopper unit 10A is the same value as the current command value I _ref ^*, and the current of the high carrier frequency chopper unit 10B. The detection value I ₂ is 0. The output voltage _Vout of the chopper device is controlled to the voltage command value _Vref ^* .

When the load current changes suddenly, it takes time until the current detection value I ₁ of the low carrier frequency chopper unit 10A follows the current command value I _ref ^* because the carrier frequency F ₁ of the low carrier frequency chopper unit 10A is low. Here, the difference between the current command value I _ref ^* and the detected current value I ₁ of the low carrier frequency chopper unit 10A is compensated by the output current I ₂ of the high carrier frequency chopper unit 10B. Since the high carrier frequency chopper unit 10B has both a short carrier cycle F ₂ and a control cycle, the output current I ₂ of the high carrier frequency chopper unit 10B rises earlier than the output current I _{1 of the} low carrier frequency chopper unit 10A.

Further, as described above, the low carrier frequency chopper unit 10A that outputs most of the current that must be supplied to the load 15 side, that is, the current command value I _ref ^* , has a low carrier frequency. Can be suppressed. On the other hand, since the high carrier frequency chopper unit 10B in which a high carrier frequency is set passes only a small amount of power, switching loss and heat generation can be suppressed. Further, since the high carrier frequency chopper unit 10B passes only a small amount of power, the carrier frequency F ₂ can be increased.

  Furthermore, since the high carrier frequency chopper unit 10B, which is a high carrier frequency, compensates for a sudden change in load current, the voltage response can be improved.

  That is, the chopper device according to the first embodiment has a low carrier frequency, converts main power by the low carrier frequency chopper unit 10A with less energy loss and heat generation in the switching elements S1 and S2, and has a high carrier frequency and high responsiveness. Compensation for improving the voltage response is performed by the high high carrier frequency chopper unit 10B.

  As described above, according to the chopper device of the first embodiment, it is possible to increase the carrier frequency and improve the responsiveness in voltage control while suppressing energy loss and heat generation in the switching element.

[Embodiment 2]
Based on FIG. 4, the operation of the control unit 30 in the second embodiment will be described. Similar to the first embodiment, the control unit 30 of the second embodiment includes a voltage control unit 21, a low-pass filter 22, a first current control unit 23, a second current control unit 24, a first PWM signal generation unit 25, and a second PWM signal. A generator 26, a first carrier generator 27, and a second carrier generator 28 are provided.

  The operations of the voltage control unit 21, the low pass filter 22, and the first current control unit 23 are the same as those in the first embodiment.

In the second embodiment, a difference between the current command value I _ref ^* and the first current command value I _1ref ^* is set as a second current command value I _2ref ^* . The first current command value I _1ref ^* filtered by the low-pass filter 22 should be almost the same value as the current detection value I ₁ of the low carrier frequency chopper unit 10A. Further, a filter for noise removal must be inserted into the current detection unit (not shown), and the response is delayed by that amount of filter. Therefore, by setting the difference between the current command value I _ref ^* and the first current command value I _1ref ^* as the second current command value I _2ref ^* , the current is almost the same as the second current command value I _2ref ^* of the first embodiment. The command value can be created and the response speed is improved.

Thereby, among the current command value I _ref ^*, a current that cannot be supplied by the output current I ₁ of the low carrier frequency chopper unit can be compensated by the output current I ₂ of the high carrier frequency chopper unit 10B.

  The effects obtained by the current control unit 24, the first and second PWM signal generation units 25 and 26, the first carrier generation unit 27, and the second carrier generation unit 28 are the same as those in the first embodiment.

   As described above, the chopper device according to the second embodiment can improve the carrier frequency and improve the voltage control responsiveness while suppressing energy loss and heat generation in the switching element.

In addition, since the difference between the current command value I _ref ^* and the first current command value I _1ref ^* is set as the second current command value I _2ref ^* , the response delay in the filter of the current detection unit is eliminated. The response speed can be improved more than 1.

DESCRIPTION OF SYMBOLS 10A ... Low carrier frequency chopper part 10B ... High carrier frequency chopper part 11, 12 ... 1st, 2nd switching module 13 ... DC power supply 15 ... Load DCL1, DCL2 ... 1st, 2nd reactor S1-S4 ... Switching element D1 to D4... Diode I ₁ ... Low carrier frequency current detection value I ₂ ... High carrier frequency current detection value V _out ... Chopper device output voltage C ... Capacitor

Claims (4)

A chopper device in which a plurality of chopper units that step down or step up a DC voltage are connected in parallel by controlling on / off of a switching element,
At least one of the plurality of chopper units is a high carrier frequency chopper unit that is set to a higher carrier frequency than other chopper units, and the control period of the high carrier frequency chopper unit is compared with other chopper units. Set it short,
From the other chopper part, output a current that is a steady component of the current command value,
The high carrier frequency chopper unit outputs a deviation current between a current command value of the chopper device and a current of the other chopper device. Two chopper parts are connected in parallel,
The control unit that outputs a gate signal to the switching element,
A voltage control unit that performs voltage control based on a deviation between the voltage command value and the output voltage detection value of the chopper device, and outputs a current command value;
A low pass filter for extracting a first current command value which is a stationary component of the current command value;
A first current control unit that performs current control based on a deviation between the first current command value and a current detection value of a low carrier frequency chopper unit in which a carrier frequency lower than that of the high carrier frequency chopper unit is set. When,
First PWM signal generation for comparing a carrier signal having a lower carrier frequency compared with a high carrier frequency chopper unit and an output of the first current control unit and outputting a gate signal to a switching element of the low carrier frequency chopper unit And
A second current control unit that performs current control based on a difference between the difference between the current command value and the current detection value of the low carrier frequency chopper unit and the current detection value of the high carrier frequency chopper unit;
Second PWM signal generation for comparing a carrier signal having a higher carrier frequency compared with the low carrier frequency chopper unit and the output of the second current control unit and outputting a gate signal to the switching element of the high carrier frequency chopper unit The chopper device according to claim 1, further comprising a portion. Two chopper parts are connected in parallel,
The control unit that outputs a gate signal to the switching element,
A voltage control unit that performs voltage control based on a deviation between the voltage command value and the output voltage detection value of the chopper device, and outputs a current command value;
A low pass filter for extracting a first current command value which is a stationary component of the current command value;
A first current control unit that performs current control based on a deviation between the first current command value and a current detection value of a low carrier frequency chopper unit in which a carrier frequency lower than that of the high carrier frequency chopper unit is set. When,
First PWM signal generation for comparing a carrier signal having a lower carrier frequency compared with a high carrier frequency chopper unit and an output of the first current control unit and outputting a gate signal to a switching element of the low carrier frequency chopper unit And
A second current control unit that performs current control based on a difference between the difference between the current command value and the first current command value and a current detection value of the high carrier frequency chopper unit;
Second PWM signal generation for comparing a carrier signal having a higher carrier frequency compared with the low carrier frequency chopper unit and the output of the second current control unit and outputting a gate signal to the switching element of the high carrier frequency chopper unit The chopper device according to claim 1, further comprising a portion. The chopper part is
A switching module comprising two switching elements connected in series and two diodes connected in antiparallel to each of the switching elements;
The chopper device according to any one of claims 1 to 3, further comprising a reactor having one end connected to an intermediate connection point of the two switching elements.

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