JP3395427B2 - Servius controller - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a celius controller for controlling speed by controlling an electromotive voltage of a secondary circuit of an induction motor for driving a so-called square load such as a pump and a fan, and more particularly to a smoothing capacitor. The present invention relates to a SELVIUS controller suitable for suppressing ripple current flowing in a cell.

[0002]

2. Description of the Related Art As a device for controlling a secondary voltage of an induction motor to perform variable speed control of the motor, a so-called rectifier element is used in a secondary circuit, and a direct current voltage which is an output thereof is regenerated to a power source by a thyristor converter. There is a static SELVIUS device, a SELVIUS device in which a rectifying element is used in a secondary circuit, and a DC voltage as an output thereof is controlled by a chopper circuit and a regenerative inverter circuit.

Incidentally, one related to the prior art is, for example, Japanese Patent Laid-Open No. 1-283078.

[0004]

In the above-mentioned prior art, since the secondary circuit capacity of the SELVIUS device is determined by the secondary circuit voltage and current of the induction motor, a converter suitable for the capacity is required. Further, the thyristor is required. In principle, the converter using the above method has a problem that a commutation failure phenomenon cannot be avoided and a problem that a starting resistor is required. In a device that controls a DC voltage with a chopper circuit and a regenerative inverter, a smoothing capacitor is required between the chopper circuit and the regenerative inverter circuit.Since this capacitor is usually weak against ripple current, a large-capacity capacitor must be prepared. There is a problem that it must be done.

An object of the present invention is to reduce the capacity of a smoothing capacitor provided between the chopper circuit and the regenerative inverter,
An object of the present invention is to provide a highly reliable SELVIUS controller.

[0006]

The above object is to provide a converter connected to a secondary circuit of an induction motor, a chopper circuit for chopping the output of the converter with a switching element, and a chopper connected to the output of the chopper circuit. A diode, a smoothing capacitor that smoothes the output of the chopper diode, a regenerative inverter that controls the voltage across the smoothing capacitor to a predetermined value, and means for generating a current feedback command Ifb from the output current of the regenerative inverter,
The current detection means for detecting the output side current of the chopper diode, the voltage detection means for detecting the voltage across the smoothing capacitor, and the detection value Vfb of the voltage detection means subtracted from the voltage setting value Vref giving the predetermined value. Means for performing a proportional-plus-integral operation on the value to generate a current command Iref;
A means for generating a current Id2 obtained by smoothing the current detected by the current detecting means, and the current Id2 from the current command Iref.
And a means for generating a compensation signal by subtracting the feedback command Ifb, and a driver circuit for outputting a drive signal to the switching element of the regenerative inverter based on the compensation signal.

The above-mentioned object is also to provide a converter connected to a secondary circuit of an induction motor, a chopper circuit for chopping the output of the converter with a switching element, a chopper diode connected to the output of the chopper circuit, and the chopper. A smoothing capacitor that smoothes the output of the diode, a regenerative inverter that controls the voltage across the smoothing capacitor to a predetermined value, a means that generates a current feedback command Ifb from the output current of the regenerative inverter, and the output current of the converter is detected. Current detecting means, speed detecting means for detecting the speed of the induction motor, means for outputting a speed command based on the set value of the speed setter and the detected value detected by the speed detecting means, and the speed command And means for generating and outputting a conduction ratio signal from the detection value of the current detection means, and a means for generating a conduction ratio signal based on the conduction ratio signal. And a means for generating and outputting a control signal for driving the switching element, a means for generating a signal Id2 from the detection value of the current detecting means and the duty ratio signal, and a voltage across the smoothing capacitor. Voltage detecting means and voltage setting value Vref for giving the predetermined value
Means for performing a proportional-plus-integral operation on a value obtained by subtracting the detection value Vfb of the voltage detecting means from the above, and a compensation signal by subtracting the signal Id2 and the feedback instruction Ifb from the current instruction Iref. And a driver circuit that outputs a drive signal to the switching element of the regenerative inverter based on the compensation signal.

[0008]

The SELVIUS controller normally performs a proportional-plus-integral operation on the value obtained by subtracting the detected value Vfb of the voltage across the voltage setting value Vref in order to control the voltage across the smoothing capacitor to a predetermined value, and then the current command Iref. However, since the operating speed of this voltage regulator is slow, the ripple of the smoothing capacitor becomes large.
Therefore, in the present invention, the output current of the chopper diode is smoothed to generate the signal Id2, or the signal Id2 is generated from the converter output current and the duty ratio signal, and this signal Id2 is generated.
The current command Iref is corrected in a feedforward manner.
This reduces the ripple of the smoothing capacitor,
The capacity of the smoothing capacitor can be small.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a celius controller according to an embodiment of the present invention. The secondary circuit of the induction motor 1 is connected to the converter 2. The output circuit of the converter 2 is connected to the chopper circuit 3, and the output of the chopper circuit 3 is connected to the chopper diode 4. The output of the chopper diode 4 is connected to the smoothing capacitor 6 via the regenerative current detector 5, and the smoothing capacitor 6 is connected to the regenerative inverter 7. The output current of the regenerative inverter 7 is output via the regenerative transformer 9. The output current of the regenerative inverter 7 is detected by the load current detector 8.

The speed detector 18 for detecting the speed of the induction motor 1 sends a detection signal to the speed controller 16, and the speed controller 16 generates a speed generated from the detection signal and the set value of the setter 17. Current controller 1 for minor control of control signals
Send to 5. The current controller 15 generates a control signal based on the output current detection value of the converter 2 and the output signal of the speed controller 16, and passes the control signal to the drive circuit 14 as a voltage command. The switching element 19 is driven.

On the other hand, the voltage controller 12 controls the basic voltage command Vref of the setter 13 and the voltage detection value Vfb of the smoothing capacitor 6.
The control command Iref is generated and output to the current controller 11. The current controller 11 that performs minor control generates a voltage command based on the control command Iref, the detection value of the regenerative current detector 5, and the detection value of the load current detector 8 and passes it to the drive circuit 10. The drive circuit 10 drives the switching element 20 of the regenerative inverter 7.

Here, the current controller 11 creates a compensation signal for operating the regenerative current faster than the current command which is the voltage control output. The operation will be described below with reference to FIG. FIG. 2 is a detailed configuration diagram around the current controller 11. The switching element 20 of the regenerative inverter 7 is
It is basically controlled by voltage control.

The voltage command Vref from the setter 13 is given so that the voltage of the smoothing capacitor 6 becomes a constant value.
The voltage controller 12 matches this voltage command Vref with the voltage feedback value Vfb of the smoothing capacitor 6.
The voltage regulator 23 performs normal proportional-plus-integral control, and outputs it as a current command Iref. The detected current value of the load current detector 8 is passed through the detection circuit 25 to the current feedback value Ifb.
And the current command Iref is matched with the feedback value Ifb. The current flowing through the switching element 19 of the chopper circuit 3 is Is, and the current flowing through the chopper diode 4 is Id. The current Id is detected by the regenerative current detector 5, and becomes the current Id2 via the detection circuit 21 and the smoothing circuit 22. Then, the feedback value Ifb and the current Id2 are subtracted from the current command Iref to generate the compensation signal 30. The current regulator 24 sends a control command to the drive circuit 10 based on the compensation signal 30, and the drive circuit 10 controls the switching element 20 of the regenerative inverter 7 to be turned on / off based on the control command.

Here, the regenerative current Id flows into the smoothing capacitor 6 and raises the voltage across the smoothing capacitor 6. As a result, closed loop control is performed by the action of the voltage regulator 23, and the power is regenerated by the power source via the switching element 20 of the regenerative inverter 7. The current flowing into the smoothing capacitor 6 at this time, that is, the ripple current, is the voltage regulator 23.
It is determined by the response speed of. In normal control, the response speed of the voltage regulator 23 is about 50 rad / s, which corresponds to 20 ms. This means that a current flows into the smoothing capacitor 6 during this 20 ms. Therefore,
For example, when the response of the voltage regulator 23 is limited due to various restrictions such as the calculation speed of the controller, increasing the apparent response of the voltage regulator 23 can reduce the ripple current flowing into the smoothing capacitor 6. Become.

The above-mentioned current Id2 functions as a regenerative current compensation signal. That is, by directly controlling the signal of Iref, the switching element 20 of the regenerative inverter 7 can be controlled at a time determined by the response of the current regulator 24. Normally, the control response of the current regulator 24 is 200 to 30.
Since it is 0 rad / s, the response time is about 3-5 ms. Therefore, the speed is 4 to 7 times as high as that in the case of controlling by the voltage regulator 23, and the ripple current of the current Ic flowing through the smoothing capacitor 6 is 1/4 to 7 depending on the speed.
It becomes 1/7.

FIG. 3 shows the relationship between the currents Is and Id, the driving pulse * A of the switching element 19 and the current Id2. The drive pulse * A repeats ON / OFF, but when ON, current flows through the chopper circuit 3, and when OFF, current flows through the chopper diode 4. Therefore, the currents Is and Id are as shown in FIG. The current Id2 is the result of passing the current Id through the smoothing circuit 22. By using the current Id2, it becomes possible to perform the regenerative operation of the regenerative inverter 7 faster than the normal control by the voltage regulator 23. As a result, the smoothing capacitor 6
The fluctuation range of the current Ic flowing through the line becomes small. FIG. 4 shows the regenerative current Id in the cervian controller to which the present invention is applied.
And a part of the simulation result of the voltage Vc of the smoothing capacitor 6 and the current Ic of the smoothing capacitor 6. In addition, FIG. 5 shows a simulation result of a conventional selbyus controller for comparison.

In this embodiment, as described above, the regenerative current Id
A regenerative compensation signal Id2 is generated from the regenerative compensation signal Id2
Since the current command Iref is corrected in a feedforward manner, the ripple of the smoothing capacitor 6 becomes small and the capacitor capacity can be reduced.

FIG. 6 is a block diagram of the SELVIUS controller according to the second embodiment of the present invention. In this embodiment, the compensation signal 30 is created using the control signal of the chopper circuit 3. The output signal of the converter current detector 29 is also input to the compensation signal calculation circuit 27 as the converter current 31. On the other hand, the duty ratio signal 28 output from the current controller 15 to the drive circuit 14 is represented as the time when the switching element 19 of the chopper circuit 3 is turned on, and this is also input to the compensation signal calculation circuit 27.

FIG. 7 shows the drive pulse 26 from the switching element 1, the chopper current Is, and the chopper diode current I.
The relationship between d and the converter current 31 is shown. The ON / OFF cycle of the drive pulse 26 is 1 / T, of which O
When the N time is represented by T1, the relationship between the converter current Icc (31) and the chopper diode current Id is represented by (T-T1) / T = Id / Icc.

Therefore, if the current flow rate is represented by K, then K = T1 / T. Using this conduction ratio signal K (28) output from the current controller 15, the compensation signal 30 (Id2) is calculated as Id2 = (1-K) * Icc. Then, the compensation signal 30 (Id2) is given to the current controller 12. The current controller 12 generates a control command from the compensation signal Id2 and the above-mentioned Iref and Ifb and gives it to the drive circuit 10, and the drive circuit 10 controls the switching element 20 to be turned on / off based on this control command.

[0021]

According to the present invention, in the SELVIUS device, the operation of the regenerative inverter can be made faster than that of only the voltage regulator, and as a result, the ripple current of the smoothing capacitor can be reduced and the smoothing capacitor The capacity can be reduced. Therefore, the number of smoothing capacitors provided in parallel can be reduced, the number of parts is reduced, and reliability is improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a selvian controller according to a first embodiment of the present invention.

FIG. 2 is a detailed configuration diagram around a current controller 11 shown in FIG.

FIG. 3 is a waveform diagram of a regenerative current signal.

FIG. 4 is a diagram showing a part of a simulation result of the Servius controller shown in FIG. 1.

FIG. 5 is a diagram showing a part of a simulation result of a conventional selbyus controller compared with FIG. 4.

FIG. 6 is a configuration diagram of a SELVIUS controller according to a second embodiment of the present invention.

7 is a waveform diagram of the regenerative current signal in FIG.

[Explanation of symbols]

1 ... Induction motor, 2 ... Converter, 3 ... Chopper circuit,
4 ... Chopper diode, 5 ... Regenerative current detector, 6 ... Smoothing capacitor, 7 ... Regenerative inverter, 8 ... Load current detector, 9 ... Regenerative transformer, 10 ... Drive circuit, 11 ... Current controller, 12 ... Voltage controller , 13 ... Basic voltage command, 1
4 ... Drive circuit, 15 ... Current controller, 16 ... Speed controller, 17 ... Speed setter, 18 ... Speed detector, 19 ... Switching element, 20 ... Switching element, 21 ... Detection circuit, 22 ... Smoothing circuit, 23 ... voltage regulator, 24 ... current regulator, 25 ... current detection circuit, 26 ... drive pulse, 27 ...
Compensation signal arithmetic circuit, 28 ... Commutation rate signal, 29 ... Converter current detector, 30 ... Compensation signal, 31 ... Converter current.

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H02P 5/28-5/44 H02P 7/36-7/66

Claims (2)

(57) [Claims] 1. A converter connected to a secondary circuit of an induction motor, a chopper circuit for chopping the output of the converter with a switching element, a chopper diode connected to the output of the chopper circuit, and an output of the chopper diode. A smoothing capacitor for smoothing, and a regenerative inverter for controlling the voltage across the smoothing capacitor to a predetermined value,
Means for generating a current feedback command Ifb from the output current of the regenerative inverter; current detecting means for detecting the output side current of the chopper diode; voltage detecting means for detecting the voltage across the smoothing capacitor; and the predetermined value. A means for performing a proportional-plus-integral operation on a value obtained by subtracting the detection value Vfb of the voltage detection means from the given voltage setting value Vref, and means for generating a current command Iref, and a current Id2 obtained by smoothing the current detected by the current detection means. Means, a means for subtracting the current Id2 and the feedback instruction Ifb from the current instruction Iref to generate a compensation signal, and a driver circuit for outputting a drive signal to the switching element of the regenerative inverter based on the compensation signal. And a SELVIUS control device. 2. A converter connected to a secondary circuit of an induction motor, a chopper circuit for chopping the output of the converter with a switching element, a chopper diode connected to the output of the chopper circuit, and an output of the chopper diode. A smoothing capacitor for smoothing, and a regenerative inverter for controlling the voltage across the smoothing capacitor to a predetermined value,
A means for generating a current feedback command Ifb from the output current of the regenerative inverter, a current detecting means for detecting the output current of the converter, a speed detecting means for detecting the speed of the induction motor, and a set value for the speed setter. A means for outputting a speed command based on the detection value detected by the speed detecting means; a means for generating and outputting a flow rate signal from the speed command and the detection value of the current detecting means; Means for generating and outputting a control signal for driving the switching element based on the signal, means for generating a signal Id2 from the detection value of the current detecting means and the duty ratio signal, and a voltage across the smoothing capacitor And a value obtained by subtracting the detection value Vfb of the voltage detection means from the voltage setting value Vref that gives the predetermined value, and a proportional-integral operation is performed to generate a current command Iref. Means, a means for subtracting the signal Id2 and the feedback instruction Ifb from the current instruction Iref to generate a compensation signal, and a driver circuit for outputting a drive signal to a switching element of the regenerative inverter based on the compensation signal. And a SELVIUS control device.