KR101661567B1 - Boost matrix converter and motor driving system using thereof - Google Patents

Abstract

The step-up type matrix converter according to the present invention includes a voltage source rectifying unit which is composed of six unidirectional switches located on the input side and converts an input three-phase alternating current into a direct current and outputs the direct current; And a current source inverter stage which is composed of six bidirectional switches located at the output side and converts the direct current outputted from the voltage source rectification stage into a three-phase alternating current and outputs the converted three-phase alternating current.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a boost converter and a motor driving system using the same,

The present invention relates to a matrix converter and a motor drive system, and more particularly, to a step-up matrix converter and a motor drive system using the same.

The matrix converter is a structure that the input power is directly connected to the output load through the power semiconductor switch (IGBT), and the output of the variable voltage and the variable frequency is synthesized. Matrix converters can be broadly divided into direct matrix converters and indirect matrix converters. The direct matrix converter is a matrix-type structure in which nine bidirectional power semiconductor switches are used. The indirect matrix converter is a DC-DC indirect energy conversion device in the structure of a conventional AC-DC-AC indirect power conversion device. Removed form. These matrix converters eliminate the electrolytic capacitors required at the dc stage, thereby reducing the size of the converter, extending the life span, and enabling energy recovery and power factor control.

However, despite the many advantages of the matrix converter, the commercialization of the matrix converter has not been done yet. A typical reason for this is that a large number of high-speed, high-power-capacity semiconductor switches and gate drivers are required and the control method is very complicated due to commutation problems compared with the conventional method. Nine bidirectional switches for implementing the matrix converter are composed of 18 unidirectional switches, and a gate driver for controlling each switch is also needed. Another reason is the low voltage transfer rate. The matrix converter has a theoretical limit of 86.6% of the voltage transfer rate due to the direct connection of the output to the input without the energy storage in the DC link. Therefore, it is difficult to use the commercial standard motor for driving the motor, and thus, there is a problem that a specially designed motor should be used.

Therefore, the research on the boost (boost) region is steadily increasing to ensure a wide output range. The most typical topology is boosting using a Z-source network. In this case, it is possible to extend the voltage transfer rate by adding a Z-source composed of L and C (a switch or a diode may be added) to the DC terminal or the input / output terminal of the matrix converter. However, The benefits of In addition, it is difficult to design capacitors of inductors and capacitors that constitute a Z-source network.

Indirect matrix converters are an alternative to traditional matrix converter topologies, allowing sinusoidal input current and output voltage, bidirectional power flow, and input power factor control. Since the capacitor is not used as an energy storage device, the lifetime of the converter can be increased. Indirect matrix converters are functionally identical to existing matrix converters and have several advantages. The number of switches in the rectifier stage can be reduced, which is called a sparse matrix converter. In addition, a multi-output system can be constructed by connecting several inverter stages to one rectification stage, and the clamp circuit for protecting the switch from overvoltage is simpler than the conventional matrix converter.

1 shows a schematic configuration of a conventional indirect matrix converter. Referring to FIG. 1, the conventional indirect matrix converter is composed of a rectifier stage 20, which is located on the input side and is composed of six bidirectional switches, and an inverter stage 30, which is located on the output side and is composed of six unidirectional switches. And an LC filter 10 for reducing harmonics is connected to the input side. An inverse parallel diode is connected to the six unidirectional switches constituting the inverter stage 30. [ The rectifier stage 20 converts the input three-phase alternating current into a direct current and outputs the direct current. The inverter stage 30 converts the direct current output from the rectifying stage 20 into a three-phase alternating current and outputs the direct current. The bidirectional switch constituting the rectifying unit 20 is a switch capable of flowing current in both directions when it is on, and has a voltage blocking characteristic when it is off. Until now, commercialized power semiconductor switches have mostly unidirectional voltage and current characteristics. Therefore, bi-directional switches combined with diodes and unidirectional switches can be used.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to provide a voltage converter that can switch the direction of electric power using a characteristic capable of bi-directional power transfer of a matrix converter in order to improve a voltage transfer rate of the matrix converter, System.

According to an aspect of the present invention, there is provided a step-up type matrix converter comprising: a voltage source rectifying unit which is composed of six unidirectional switches located on an input side and converts an input three-phase alternating current into a direct current; And a current source inverter stage which is composed of six bidirectional switches located at the output side and converts the direct current outputted from the voltage source rectification stage into a three-phase alternating current and outputs the converted three-phase alternating current.

The step-up matrix converter may further include an LC filter disposed on the output side.

The current source inverter stage may be composed of three common collector type switches and three common emitter type switches.

The boost type matrix converter may further include a protection circuit composed of six diodes and one capacitor connected between a common collector of the common collector type switch and a common emitter of the common emitter type switch.

According to an aspect of the present invention, there is provided an electric motor drive system including the above-described step-up type matrix converter, wherein the input side is connected to a generator, and the output side is connected to an electric motor.

Wherein the motor drive system includes: a control unit for generating a command signal for controlling the switches of the voltage source rectification stage and the current source inverter stage; And a pulse width modulation unit for applying a pulse width modulation signal to the switches according to the command signal.

Wherein the control unit comprises: a CSI controller for generating a phase command of an input-side command current and an output-side current based on an actual speed, a speed command, and an output-side current of the electric motor; And a VSR controller for generating an input voltage command based on the actual speed of the generator and the input side command current and the input side current, wherein the phase command of the output side current is applied to the current source inverter stage, It can be applied to the rectifying end of the voltage source.

The CSI controller generates the phase command of the output side current and the input side command current so that the output side current follows the output command current obtained from the difference between the speed command and the actual speed of the motor, Side command current so as to follow the input-side command current.

According to the present invention, there is provided a step-up type matrix converter in which the voltage transfer rate is about 1.15 times or more by reversing the direction of the input and output of the conventional matrix converter, thereby performing the step-up operation. Further, according to the present invention, there is provided an electric motor drive system capable of controlling the speed of an electric motor using such a step-up matrix converter.

1 shows a schematic configuration of a conventional indirect matrix converter.
Fig. 2 shows a schematic configuration of a step-up matrix converter according to an embodiment of the present invention.
3 shows an example of a bi-directional switch.
4A to 4E show the principle in which the voltage is boosted in the step-up matrix converter.
5 shows a configuration of a motor drive system using a step-up matrix converter according to an embodiment of the present invention.
6 shows a more specific configuration of the control unit 400 in the motor drive system using the step-up matrix converter.
Fig. 7 shows a more specific configuration of the CSI controller 412. Fig.
Fig. 8 shows a more specific configuration of the VSR controller 422. Fig.
9 shows an example of response characteristics of the speed command and the actual speed in the motor drive system according to the embodiment of the present invention.
10 shows an example of input / output line voltage and input / output current in a motor drive system according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the following description and the accompanying drawings, substantially the same components are denoted by the same reference numerals, and redundant description will be omitted. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

Fig. 2 shows a schematic configuration of a step-up matrix converter according to an embodiment of the present invention. The step-up matrix converter according to the present embodiment reverses the direction of input and output of a conventional matrix converter as shown in FIG. 1 by using a characteristic capable of bi-directional power transfer. Therefore, the voltage transfer rate is always 1.15 times or more, so that the boost operation is possible.

Matrix converter according to the present embodiment is located on the input side of the six-way switch, a voltage source rectifier stage constituted by (S _rt, S _st, S _tt, S _rb, S _sb, S _tb) (Voltage Source Rectifier, VSR) (100 A current source inverter (CSI) 200 located at the output side and composed of six bidirectional switches S _ct , S _bt , S _at , S _cb , S _bb and S _ab , Filter 200 (C _f , L _f ). Although not shown, an input side inductor is provided on the input side. The voltage source rectification stage 100 converts the input three-phase alternating current into a direct current and outputs the direct current. The current source inverter stage 200 converts the direct current output from the voltage source rectification stage 100 into a three-phase alternating current .

When the input is used as a generator, the output often requires a voltage greater than the input. In this case, the advantages of the boost type matrix converter can be maximized by using the voltage source as the generator and the current source as the load.

The six bidirectional switches S _ct , S _bt , S _at , S _cb , S _bb and S _ab constituting the current source inverter stage 200 can flow current in both directions when turned on, Lt; / RTI > Until now, commercialized power semiconductor switches have mostly unidirectional voltage and current characteristics. Therefore, bi-directional switches combined with diodes and unidirectional switches can be used. For example, as the bidirectional switch, a common collector type, a common emitter type, a diode embedded switch, and two anti-parallel RIGBTs as shown in FIG. 3 can be used.

The modulation of the step-up matrix converter according to the embodiment of the present invention is the same as that of a general matrix converter. In the case of the voltage source rectification stage 100, boosting of the input voltage occurs when a zero vector is applied. That is, through the control of the switches of the step-up matrix converter, the magnetic energy stored in the input-side inductor can be released as the electric energy of the output-side capacitor C _f , so that the output-side voltage can be boosted higher than the input-side voltage.

4A to 4E are views showing the principle of voltage boosting in the step-up matrix converter.

4A shows a case where all of the input side top switches S _rt , S _st and S _tt are ON and the input voltage is shorted through the input side inductors L _r , L _s and L _t , It is zero the magnetic energy at the input inductor _{(L r, L s, L} t) is accumulated.

As the degree of off-input R the top switches (S _rt) from 4b is the magnetic energy of the inductor has been the current is flowed is accumulated to a DC-stage discharge into electrical energy at the output capacitor _{(C a, C b, C} c) applied to the load do.

Similarly, Fig. 4c in the input side of the top of the switch S (S _st) the magnetic energy of the inductor has been stored as off is discharged into an electric energy to the output side capacitor _{(C a, C b, C} c).

In FIG. 4D, the magnitude of the DC short-circuit current becomes zero while the input-side T-top switch S _tt is turned off. The input voltage is the magnetic energy at the input inductor is short-circuited through the _{(L r, L s, L} t) input side of the inductor _{(L r, L s, L} t) is accumulated.

In FIG. 4E, on / off of the output side switch occurs when all of the top switches (S _rt , S _st , S _tt ) on the input side are on or off (zero vector applied period), so there is no switching loss on the output side.

Referring to FIGS. 4A to 4E, in the case of the output side inverter, one of the upper two-way switch and the lower one of the two-way switch are turned on at the same time. When the on-switch is located on a different phase, the switch is in an active state and power is delivered to the load. Therefore, the output line voltage across the output filter is equal to the DC voltage.

In the case of a conventional matrix converter, the output voltage is always smaller than the input voltage and has a maximum voltage transfer rate of 0.866. Therefore, in the case of a step-up matrix converter, the direction of input and output changes, so the minimum voltage transfer rate is 1 / 0.866, or about 1.15.

5 shows a configuration of a motor drive system using a step-up matrix converter according to an embodiment of the present invention.

In the motor drive system according to the present embodiment, the input side is connected to the generator 600 and the output side is connected to the electric motor 700. The generator 600 may be, for example, a three-phase synchronous generator, and the motor 700 may be, for example, a three-phase permanent magnet synchronous motor.

As described above, the motor drive system includes a step-up type matrix converter composed of a voltage source rectification stage 100, a current source inverter stage 200 and an LC filter 200, a voltage source rectification stage 100 and a switch And a pulse width modulator 500 for applying a pulse width modulated signal to the switches according to a command signal of the controller 400. [

The step-up matrix converter may further include a protection circuit 210 located on the output side and composed of six diodes and one capacitor as shown in the figure. For this purpose, the bidirectional switches of the current source inverter stage 200 may be configured as a common collector type in the upper end and a common emitter type in the lower end. A diode and a capacitor are connected between the common collector of the upper switch and the common emitter of the lower switch, so that the protection circuit 210 can be constructed. The protection circuit 210 protects the switch from the over-voltage due to the over-voltage and the inductance component of the capacitor C _f of the LC filter 300.

The capacitors of a typical back-to-back converter are separated so that the rectification stage and the inverter stage can be separately controlled. For example, the grid side inverter of the grid-connected inverter maintains the DC voltage constant and the rectifier end of the power source controls the appropriate power. Power is transferred through the rectifier and the inverter, and the dc capacitor is charged or discharged. However, since the matrix converter does not have a DC capacitor, a more stable load is required and a low dynamic response characteristic is obtained. Therefore, a stable control system should be developed through control of input and output. A step-up matrix converter for motor drive must produce high quality 3-phase voltage / current regardless of load.

6 shows a more specific configuration of the control unit 400 in the motor drive system using the step-up matrix converter.

6, the control unit 400 includes a VSR controller 422 for controlling the voltage source rectification stage 100 and a CSI controller 412 for controlling the current source inverter stage 200. [ The pulse width modulation unit 500 is divided into a PWM 510 and a PWM 520. The PWM 510 supplies a pulse width modulation signal to the switches of the voltage source rectification stage 100 according to the command of the VSR controller 422 And the PWM 520 applies a pulse width modulation signal to the current source inverter stage 200 in accordance with the command of the CSI controller 412. [

Control of the output side in the control unit 400, that is, control of the current source inverter stage 200 will be described as follows.

The torque command (T _e ^*) is generated using the difference between the electric motor 700, the speed command (ω _m ^*) and the actual speed (ω _m). That is, the subtractor 413 produces a speed command (ω _m ^*) and the actual speed (ω _m), the difference (Δω _m), the output, and the PI controller 414 of the torque command (T _e ^*) from Δω _m . The torque command T _e ^* is amplified by the amplifier 415 by (1 / K _t ) (K _t is a torque constant), and becomes the output command current i _{qe_inv} ^* for the q axis of the electric motor 700. This output reference current (i _{qe_inv} ^*) is input to CSI controller 412 with the output reference current (i _{de_inv} ^* = 0) of the d-axis of the motor 700.

The actual speed (ω _m) of the motor is converted to a phase (θ _m) by the integrator 410, the motor via the abc-dq conversion (411) from the output-side phase currents (i _a, i _b) and the phase (θ _{m) Iqe_inv} , i _{de_inv} , and [theta] _m are input to the CSI controller 412. The actual current ( _{iqe_inv} , i _{de_inv} )

The CSI controller 412 uses the difference between the output command current _{iqe_inv} ^* and i _{de_inv} ^* and the actual current _{iqe_inv} and i _{de_inv} of the motor 700 to calculate the phase command? _Inv ^* of the output side current, The current command (-i _{qe_rec} ^* ), and the modulation signal (d _a ). Since the matrix converter does not have a regulator at the dc terminal, the command generated through the CSI controller 412 indicates the amount of power required at the load side, and provides power at the input side thereof.

Fig. 7 shows a more specific configuration of the CSI controller 412. Fig. In driving a motor using a boost type matrix converter, a current source inverter stage 200 composed of a bidirectional switch controls the magnitude and phase of a current. That is, the value of the output current (i _{de_inv,} i _{qe_inv)} and phase information (θ _m) an output current (i _{de_inv,} i _{qe_inv),} the output command current through the internal reference so as to follow the ^{_{(i de_inv *, i qe_inv *}} ) . This internal command is used as the current phase command? _Inv ^* of the switching of the current source inverter stage 200 through the error between the actual current and the command current.

7, it can be _seen from the difference between the output command current ( _{iqe_inv} ^* , i _{de_inv} ^* ) and the output side current (i _{qe_inv} , i _{de_inv} ) that the input side command current (-i _{qe_rec} ^* , -i _{de_rec} ^* ) . The current phase command? _Inv ^* is obtained from the input side command current (-i _{qe_rec} ^* , -i _{de_rec} ^* ) and the phase information (? _M ) through the _dq- ? Conversion and the arc tangent transformation and applied to the PWM 520 . Here, instead of the PI (Proportional Integral) controller, a PR (Proportional Resonant) controller may be used. In the PWM 520, the phase of the output stage and the duty ratio of the switching can be obtained through the internal command value thus generated. Through this process, the pulse width modulation signal for each switch can be obtained and compared with the carrier, it is applied to the actual switch.

The control of the input side control, that is, the control of the voltage source rectification stage 100, in the control unit 400 will be described below.

Referring back to Figure 6, the input side command current i _{qe_rec} ^* inverted by the inverter 416 from -i _{qe_rec} ^* from the CSI controller 412, _along with the command current i _{de_rec} ^* = 0, is applied to the VSR controller 422 And the modulated signal d _a is input from the CSI controller 412. The reason why the modulated signal d _a is input to the VSR controller 422 is to obtain stable commutation by synchronizing switching of the voltage source rectification stage 100 and the current source inverter stage 200. On the other hand, the actual speed? _G of the generator 600 is converted to the phase? _G by the integrator 421 and is converted from the input side phase currents i _a and i _b and phase _g to abc-dq conversion I _{de_rec} , i _{qe_rec} are obtained through the input terminals 423 and 423 and i _{de_rec} , i _{qe_rec} , and θ _g are input to the VSR controller 422. The value obtained by converting the current phase command? _Inv ^* , phase information? _M and the output side phase voltages e _ab and e _bc from the CSI controller 412 by the _abc- ? Conversion 420 is PWM (510).

The VSR controller 422 controls the voltage source rectification stage 100 to control the magnitude and phase of the input side current. In other words, VSR controller 422 is input instruction current _{^{(i de_rec *, i qe_rec *}} ) as an input side current by using the difference between (i _{de_rec,} i _{qe_rec),} input-side current (i _{de_rec,} i _{qe_rec)} the input command current ( (v _r ^* , v _s ^* , v _t ^* ) for the voltage source rectification stage 100 so as to follow the input voltage command v i ^* , i _{de_rec} ^* , i _{qe_rec} ^* In the PWM 510, the duty ratio of the switch is determined through this command.

Fig. 8 shows a more specific configuration of the VSR controller 422. Fig.

The command voltage v _{de_rec} ^* , v _{qe_rec} ^* for the dq axis is _calculated by the PI controller from the difference between the input side command current i _{de_rec} ^* , i _{qe_rec} ^* from the CSI controller 412 and the input side current i _{de_rec} , i _{qe_rec} , ) Is obtained. reference voltage for the dq-axis ^{_{(v de_rec *, v qe_rec *}} ) and through a dq-abc converted from the phase information (θ _g), input-side current (i _{de_rec,} i _{qe_rec)} a command current (i _{de_rec} ^*, i _{qe_rec} ^* (V _r ^* , v _s ^* , v _t ^* ) to follow the voltage command (v _r ^* , v _s ^* , v _t ^* ).

9 shows an example of the response characteristics of the speed command (ω _m ^*) and the actual speed (ω _m) in the electric motor drive system according to an embodiment of the present invention. In FIG. 9, it can be seen that the actual speed? _M of the electric motor follows the speed command? _M ^* .

10 shows an example of input / output line voltage and input / output current in a motor drive system according to an embodiment of the present invention.

The present invention has been described with reference to the preferred embodiments. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the present invention is defined by the appended claims rather than by the foregoing description, and all differences within the scope of equivalents thereof should be construed as being included in the present invention.

Claims (8)

A motor drive system comprising a step-up matrix converter,
Wherein the step-up matrix converter comprises: a voltage source rectifying unit which is disposed on the input side and is composed of six unidirectional switches and converts the input three-phase alternating current into a direct current and outputs the direct current; And a current source inverter stage which is composed of six bidirectional switches located at the output side and converts a direct current outputted from the voltage source rectification stage into a three-phase alternating current and outputs the three-phase alternating current, the input side is connected to a generator, Connected -;
A control unit for generating a command signal for controlling the switches of the voltage source rectification stage and the current source inverter stage; And
And a pulse width modulation unit for applying a pulse width modulation signal to the switches according to the command signal,
Wherein,
Generating an output command current by using the torque command, integrating an actual speed of the electric motor to obtain electric motor phase information, and outputting the electric motor phase information by using the difference between the speed command and the actual speed of the electric motor, The actual speed is integrated to obtain the generator phase information,
A CSI controller for generating an input side command current using the difference between the output command current and the output side current and generating an output side current phase command using the difference between the output command current and the output side current and the motor phase information; And
And a VSR controller for generating an input voltage command using the difference between the input side command current and the input side current and the generator phase information,
Wherein the pulse width modulator comprises:
A first pulse width modulator for applying a first pulse width modulation signal to the current source inverter stage according to the output side current phase command from the CSI controller; And
And a second pulse width modulator for applying a second pulse width modulation signal to the voltage source rectification stage in accordance with the input voltage command from the VSR controller. The method according to claim 1,
Wherein the step-up matrix converter further comprises an LC filter positioned on the output side. The method according to claim 1,
Wherein the current source inverter stage is composed of three common-collector-type switches and three common-emitter-type switches. The method of claim 3,
Wherein the boost type matrix converter further comprises a protection circuit composed of six diodes and one capacitor connected between a common collector of the common collector type switch and a common emitter of the common emitter type switch. Drive system. delete delete delete delete

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