JP2006262573A - Control device of ac-ac power converter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive control device that can prevent the breakage of an accumulator or the like at regenerative operation, without using a large-sized energy processing circuit. <P>SOLUTION: The AC-AC power converter, such as a matrix converter, which converts an AC power supply voltage to an AC voltage of an arbitrary magnitude and frequency and feeds it to a motor, comprises a means 7 that detects the current of the synchronous motor 8; a coordinate conversion means 64 that converts a current detection value to a d-axis current parallel with motor magnetic flux and a q-axis current orthogonal to the motor magnetic flux; a current-regulating means 62 that regulates the output voltage of the matrix converter 5 so that the d-axis current and the q-axis current agree with the d-axis current command and a q-axis current command, respectively; and a d-axis current command regulating means 61 that regulates the d-axis current command and increases the motor current, when energy is regenerated to the converter 5 side from the motor 8. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a control device for an AC / AC power converter that converts a multi-phase AC voltage into an AC voltage having an arbitrary magnitude and frequency by using a semiconductor switching element, for example, a large energy such as a matrix converter. The present invention relates to an energy processing means when energy is regenerated from the motor to the power converter side when the motor is driven by a semiconductor power converter having no buffer.

A matrix converter is known as an example of a semiconductor power converter that performs AC / AC direct conversion without having a large energy buffer.
Hereinafter, as a prior art, a system for driving an electric motor using a matrix converter will be described.

FIG. 10 is a circuit configuration diagram of an elevator system described in Patent Document 1 described later.
In FIG. 10, 51 is a three-phase AC power source, 52 is a contactor, 60 is a matrix converter, 70 is an AC motor for driving an elevator, 81 is a hoisting machine, 82 is a counterweight, and 83 is a car. 53 is a power failure detector for detecting a power failure of the AC power supply 51, 54 is a load detector, 55 is for switching the AC switch of the matrix converter 60 based on the output signals of the power failure detector 53 and the load detector 54. A control device 56 is a control circuit that outputs a control signal to the semiconductor switch 58 based on the voltage of the power failure detector 53 and the storage battery 90, 57 is a resistor for regenerative energy consumption, and 59 is a contactor.

In the above configuration, since the matrix converter 60 does not have a large energy buffer such as an electrolytic capacitor, the operation cannot be continued if a power failure occurs in the AC power supply 51.
Therefore, when a power failure is detected by the power failure detector 53, the contactor 52 is opened to disconnect the AC power source 51, and then the contactor 59 is turned on to connect the storage battery 90 to the input side of the matrix converter 60, thereby controlling the controller 55. Emergency operation during power outages.

During such an emergency operation, the hoisting machine 81 is in a regenerative operation due to the load balance between the counterweight 82 and the car 83, and when energy is regenerated to the storage battery 90 via the electric motor 70 and the matrix converter 60, the storage battery 90 is There is a risk that the AC switch of the storage battery 90 or the matrix converter 60 may be damaged due to overcharging.
For this reason, in the above prior art, the voltage of the storage battery 90 is detected and input to the control circuit 56, and when the voltage exceeds a predetermined threshold value, the semiconductor switch 58 is turned on by the control circuit 56 to resist the regenerative energy. 57 is consumed.
With the above operation, it is possible to prevent the storage battery 90 and the AC switch from being damaged during the regenerative operation.

Japanese Patent Laid-Open No. 2004-189482 ([0013] to [0016], FIG. 1 etc.)

  In the above prior art, all the energy regenerated in the storage battery 90 during emergency operation is consumed by the resistor 57, and there is a possibility that the external circuit and device for energy processing including the resistor 57 may be increased in size. Further, the external circuit also requires a control circuit 56 for driving the semiconductor switch 58, which causes a cost increase.

  SUMMARY OF THE INVENTION Accordingly, a problem to be solved by the present invention is to provide a control device that is simple and inexpensive in construction and that prevents damage to a storage battery or the like during regenerative operation without using a large energy processing circuit.

In order to solve the above problems, the invention described in claim 1 is an AC / AC power converter that converts an AC power supply voltage into an AC voltage of an arbitrary magnitude and frequency and supplies the AC voltage to an electric motor.
Means for detecting the current of the motor;
Coordinate conversion means for converting a current detection value by this means into a d-axis current parallel to the motor magnetic flux and a q-axis current orthogonal thereto;
Current adjusting means for adjusting the output voltage of the power converter so that the d-axis current and the q-axis current match the d-axis current command and the q-axis current command, respectively;
D-axis current command adjusting means for adjusting the d-axis current command to increase the motor current when energy is regenerated from the motor to the power converter side.

The invention described in claim 2 is an AC / AC power converter that converts an AC power supply voltage into an AC voltage of an arbitrary magnitude and frequency and supplies the AC voltage to an electric motor.
Means for controlling the output voltage of the power converter based on a d-axis current command parallel to the motor magnetic flux and a q-axis current command orthogonal thereto;
D-axis current command adjusting means for adjusting the d-axis current command to increase the motor current when energy is regenerated from the motor to the power converter side.

The invention described in claim 3 is the invention according to claim 1 or 2,
The AC / AC power converter is capable of emergency operation using an emergency power supply when the AC power supply voltage drops,
The motor current is increased by the operation of the d-axis current command adjusting means during emergency operation, and regenerative energy is consumed by the motor.

The present invention can be applied to a synchronous motor or an induction motor as described in claims 4 and 5.
Furthermore, as described in claim 6, the present invention can be directly applied to a matrix converter or the like that directly converts an AC power supply voltage to an AC voltage without having a large energy buffer such as an electrolytic capacitor. is there.

According to the first aspect of the present invention, in the control device having the current adjusting means, the motor current is increased by controlling the d-axis current command so that the regenerative energy is consumed by the primary winding of the motor, and external energy processing is performed. Circuits can be eliminated or processing energy can be reduced.
According to the second aspect of the present invention, in the control device having no current adjusting means, the regenerative energy is consumed by the primary winding of the electric motor by controlling the d-axis current command as in the first aspect. The energy processing circuit can be made unnecessary and the processing energy can be reduced.

Further, as described in claim 3, regenerative energy prevents an emergency power source such as a storage battery from being overcharged, thereby preventing damage to the emergency power source and the semiconductor switching element of the power converter. be able to.
Furthermore, the present invention can be applied to driving either a synchronous motor or an induction motor, and loss of control is not increased during normal operation other than during emergency operation, and control switching can be realized smoothly. is there.

  In general, according to the present invention, it is possible to provide a control device that does not require a large-scale energy processing circuit or processing device outside and that has a simple configuration and is inexpensive.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, FIG. 1 is a block diagram showing a first embodiment of the present invention, in which a synchronous motor is driven by a matrix converter as an AC / AC power converter.
In FIG. 1, 1 is a three-phase AC power source, 2 is a changeover switch, 3 is an emergency storage battery, and when a power failure of the power source 1 is detected by a power failure detector (not shown), The power source is switched from the AC power source 1 to the emergency storage battery 3.

  A matrix converter 5 is connected to the output side of the changeover switch 2 via an input filter 4. The configuration of the matrix converter 5 is well known and will not be described in detail. For example, an AC switch that can control current in both directions by connecting two semiconductor switching elements such as IGBTs in reverse parallel is provided on each of the three-phase input sides. A total of nine are connected between the phase (R, S, T phase) and each phase (U, V, W phase) on the three-phase output side.

  Reference numeral 6 denotes matrix converter control means, which will be described later, which generates and outputs drive pulses for the semiconductor switching elements. Reference numeral 7 denotes current detection means for detecting the current of each phase of the three phases from the two-phase current of the synchronous motor 8, and its output is input to the matrix converter control means 6.

Next, FIG. 2 is a block diagram showing the configuration of the matrix converter control means 6.
In this embodiment, the current of the synchronous motor 8 is separated into an axis (d-axis) component parallel to the rotating magnetic flux and an axis (q-axis) component orthogonal thereto, and vector control for controlling the torque with high accuracy is performed. ing. Since the contents of vector control are publicly known, detailed description is omitted here.

In FIG. 2, the coordinate conversion means 64 converts the current information detected by the current detection means 7 into a d-axis current _id and a q-axis current _iq and outputs the result. The current adjusting means 62 outputs the output voltage commands v _d ^* and v _q so that the d-axis current i _d and the q-axis current i _q coincide with the d-axis current command i _d ^** and the q-axis current command i _q ^* , respectively. ^{* Is} generated and output.
The coordinate conversion means 63 to which the output voltage commands v _d ^* and v _q ^* are input converts the output voltage commands v _d ^* and v _q ^* from the d and q rotation coordinates to the alternating current component on the stationary coordinates, and thereby three-phase. Output voltage commands v _u ^* , v _v ^* , and v _w ^* for each phase are generated and output to the matrix converter pulse calculation means 65.
The matrix converter pulse calculation means 65 generates a pulse pattern of the AC switch constituting the matrix converter 5 in accordance with the output voltage commands v _u ^* , v _v ^* , v _w ^* , and a total of 18 semiconductors based on this pattern. A drive pulse (PWM pulse) for the switching element is generated to switch the matrix converter 5. As a result, the synchronous motor 8 is driven by the matrix converter 5.

Next, the configuration and operation of the d-axis current command adjusting means 61, which is the main part of this embodiment, will be described.
First, FIG. 3 shows an equivalent circuit of a synchronous motor (for example, a permanent magnet type synchronous motor), and FIG. 4 shows a vector diagram of voltage and current on d and q rotation coordinates. In these diagrams, e is a matrix converter. the terminal voltage of the power converter etc., i is the motor current, R ₁ is the resistance of the primary winding, L ₁ is also inductance, e _m is the speed electromotive force, omega primary angular frequency of the power converter, [psi is the electric motor The flux linkage.

Now, in the configuration of FIG. 1, it is assumed that the power source 1 has a power failure, the power is supplied from the emergency storage battery 3 via the changeover switch 2, and the matrix converter 5 is in emergency operation.
At this time, the energy P generated on the secondary side of the synchronous motor 8 is expressed by Equation 1 when iron loss is ignored.
[Equation 1]
P ₌ e m _{i q}

Speed electromotive force e _m is the product of as a primary angular frequency ω and the flux linkage Ψ shown in FIG. 3, the energy generated P, the speed electromotive force e _m and q-axis current i _q as Equation 1 since the product of the (current component parallel to the generated torque) is generated energy P is independent of the magnitude of the d-axis current i _d.

On the other hand, the loss generated in the primary winding of the electric motor 8 is expressed by Equation 2.
[Equation 2]
P _loss = √ {(ωL ₁ ) ² + (R ₁ ) ² } × i ² = Z _m i ²
Z _m is the impedance of the primary winding.

Therefore, neglecting losses in the matrix converter 5, the energy P _in regenerating at the emergency battery 3 becomes Equation 3.
[Equation 3]
P _in = P−P _loss

As shown in FIG. 4, there is a relationship of Formula 4 between the current i, the d-axis current i _d , and the q-axis current i _q .
[Equation 4]
^{_{i = √ (i d 2 +}} i q 2)
Therefore, by increasing the current i actively passing a d-axis current i _d, increased loss P _loss by Equation 2, the energy P _in the reducing regenerated in emergency battery 3 by Equation 3 It becomes.
For example, the current i when the d-axis current i _d is supplied by the same amount as the q-axis current i _q is √2 times that when the d-axis current _id is zero from Equation 4, and the primary winding of the motor 8 in loss P _loss to occur, since doubled by equation 2, it is possible to reduce the regenerative energy P _in correspondingly.

Here, when determining the regenerative energy _{P in} is zero (i.e. _{P = P loss)} become such d-axis current _{i d,} from Equation 1, so that Equation 5.

When the synchronous motor 8 is driven, since the d-axis current is normally flowed in the negative direction in order to lower the terminal voltage of the power converter, the d-axis current command i _d ^* can be expressed by the equation 6 from the equation 5.

That is, if the d-axis current _id is controlled based on Expression 6, all the generated energy P on the secondary side of the electric motor 8 is consumed by the primary winding and is not regenerated in the emergency storage battery 3. Therefore, there is no fear that the storage battery 3 is overcharged, and an external regenerative energy processing circuit such as a resistor and a semiconductor switch as shown in the prior art becomes unnecessary.

Further, when the generated energy P on the secondary side is large and is consumed by the primary winding, overheating of the electric motor 8 becomes a problem. As shown in Equation 7, the d-axis current command i _d ^** is set to the upper limit value ( If the regenerative energy processing circuit is added, the processing energy can be reduced by controlling to a value between the lower limit (−i _dmax ) and the lower limit (−i _dmax ). It will not be a factor to increase the occupied space and cost. For example, if i _dmax is _set to the rated current of the electric motor 8, the maximum value of the electric motor current is √2 times the rated current.

Figure 5 is an upper limit value and to set the lower limit value by controlling the d-axis current command i _d ^*, the final d-axis current command i d-axis current command adjusting means in obtaining the _d ^** as Equation 7 61 is a block diagram.
In FIG. 5, the calculation means 611 calculates the right side of Formula 6 using the q-axis current i _q , the angular frequency ω, and the motor parameters (primary winding resistance R ₁ and inductance L ₁ ), and this is calculated as a d-axis current command. Output as the upper limit of i _d ^* . This upper limit value or d-axis current command “0” during normal operation is input to the low-pass filter 613 via the changeover switch 612 that switches to the calculation means 611 side during emergency operation due to a power failure, and the output is input to the limiter 614 as an upper limit value. Is set. The lower limit value of the limiter 614 is set to −i _dmax as described above.
The low-pass filter 613 is d-axis current command during emergency operation when the switch ⁱ _{d *} ⁽ⁱ _{d ^**)} is inserted in order to prevent the jumping.

With the above configuration, if the d-axis current command i _d ^* input to the d-axis current adjusting means 61 in FIG. 2 is within the range of the upper and lower limit values of the limiter 614 during emergency operation due to a power failure, i _d ^** Is output to the current adjusting means 62. If the value deviates from the upper and lower limit values, the upper limit value (the value on the right side of Equation 6) or the lower limit value (−i _dmax ) is limited and output.
FIG. 6 is a flowchart showing a series of these operations. In normal operation, “0” is set to the changeover switch 612 as described above (step S3), and in emergency operation, the d-axis current is passed through steps S1, S2, and S4. The command i _d ^* is controlled within the range between the upper limit value and the lower limit value (S5 to S8), and is output as i _d ^** .
As described above, in this embodiment, the d-axis current command is automatically controlled during the emergency operation to increase the current of the electric motor 8, so that the regenerative energy can be appropriately processed without using the regenerative energy processing circuit. It is.

In FIG. 5, the d-axis current command i _d ^** is controlled using the upper limit value and the lower limit value, but the value calculated by the right side of Equation 6 may be used as it is as the d-axis current command i _d ^**. Good. Further, the d-axis current command is controlled to be negative in order to lower the output voltage of the matrix converter 5 that drives the synchronous motor 8, but it may be a positive value. Even when the d-axis current command is positive, the current flowing in the primary winding of the electric motor 8 is the same from Equation 4.
Furthermore, there are various calculation methods for the d-axis current command i _d ^** , but any calculation method and calculation means for increasing the motor current to process the regenerative energy by the motor during emergency operation can be used in the present invention. It is included in.

Next, a second embodiment of the present invention will be described with reference to FIG. In this embodiment, the induction motor 10 is driven by the matrix converter 5, and the current detection means 7 in FIG. 1 is removed.
FIG. 8 is a block diagram showing the configuration of the matrix converter control means 9 in FIG. In this embodiment, since there is no current detection means as described above, the output voltage calculation means 92 uses the motor parameters from the q-axis current command i _q ^* and the d-axis current command i _d ^** to output voltage command v _d ^*. , V _q ^* is calculated. Since various methods for calculating v _d ^* and v _q ^* are known, description thereof will be omitted.

The operations of the coordinate conversion means 93 and the matrix converter pulse calculation means 94 in FIG. 8 are the same as those of the coordinate conversion means 63 and the matrix converter pulse calculation means 65 in FIG.
Hereinafter, the configuration and operation of the d-axis current command adjusting means 91, which is the main part of the present embodiment, will be described with reference to FIG. In FIG. 8, a q-axis current command i _q ^* is input to the d-axis current command adjustment means 91 together with the d-axis current command i _d ^* .

In FIG. 9, 911 is a calculation means to which q-axis current command i _q ^* , angular frequency ω, and motor parameter are input. This calculation means 911 calculates the lower limit value of the d-axis current command by performing the calculation of Equation 8. Ask.

When the load is the induction motor 10 as in the present embodiment, since the induction motor 10 generates the motor magnetic flux by the d-axis current, normally, a constant positive rated d-axis current (rated magnetic flux) regardless of the load. Current) i _dset is flowing. Therefore, in order to reduce the regenerative energy _{P in} increasing the loss _{P loss} occurring in the primary winding of the induction motor 10, the d-axis current _{i d} may be increased from the rated d-axis current _{i dset.}
Note that the lower limit value shown in Formula 8 is simply obtained by calculation in the same manner as when the load is a synchronous motor. That is, in the case of an induction motor, the motor magnetic flux changes when the d-axis current is adjusted, but it is assumed that when the d-axis current exceeds the rated value, the motor magnetic flux is saturated and the generated energy on the secondary side of the motor does not change. It is the value obtained after doing.

In FIG. 9, the lower limit value of the d-axis current command expressed by Equation 8 or the rated d-axis current i _dset during normal operation is _sent to the low-pass filter 913 via a changeover switch 912 that switches to the computing means 911 during an emergency operation due to a power failure. The output is set in the limiter 914 as the lower limit value. The upper limit value of the limiter 914 is, for example, the d-axis current maximum value i _dmax set to twice the rated d-axis current. By setting the upper limit value in this way, damage due to overheating of the induction motor 10 is prevented. be able to.

That is, in this embodiment, during an emergency operation due to a power failure, if the d-axis current command i _d ^* input to the d-axis current adjusting means 91 in FIG. 8 is within the range of the upper and lower limit values of the limiter 914, i It is output to the output voltage calculation means 92 as _d ^** . If the value deviates from the upper and lower limit values, the output is limited to the upper limit value ( _idmax ) or the lower limit value (the value on the right side of Equation 8).
That is, the d-axis current command i _d ^** is controlled within the range of Equation 9.

In the present embodiment, the load is an induction motor 10, when the load is a synchronous motor, using the i _q ^* instead of i _q in equation 6 described above, can be controlled by using the control block of FIG. 5 It is. Further, when the load is an induction motor in the first embodiment, control can be performed using the control block of FIG. 9 if i _q is used instead of i _q ^* in the above-described Expression 8.
Furthermore, the present invention can be applied not only to an AC / AC power converter such as a matrix converter that does not have a large energy buffer, but also to an inverter device having a conventional energy buffer.

1 is a block diagram showing a first embodiment of the present invention. It is a block diagram which shows the structure of the matrix converter control means in FIG. It is an equivalent circuit diagram of a synchronous motor. FIG. 4 is a vector diagram of voltage and current on rotational coordinates in FIG. 3. It is a block diagram which shows the structure of the d-axis current command adjustment means in FIG. It is a flowchart which shows the operation | movement of FIG. It is a block diagram which shows 2nd Embodiment of this invention. It is a block diagram which shows the structure of the matrix converter control means in FIG. It is a block diagram which shows the structure of the d-axis current command adjustment means in FIG. It is a circuit block diagram which shows a prior art.

Explanation of symbols

1: Three-phase AC power supply 2: Changeover switch 3: Emergency storage battery 4: Input filter 5: Matrix converter 6, 9: Matrix converter control means 7: Current detection means 8: Synchronous motor 10: Induction motor 61: d-axis current command Adjustment means 62: Current adjustment means 63, 64: Coordinate conversion means 65: Matrix converter pulse calculation means 611: Calculation means 612: Changeover switch 613: Low pass filter 614: Limiter 91: d-axis current command adjustment means 92: Output voltage calculation means 93: Coordinate conversion means 94: Matrix converter pulse calculation means 911: Calculation means 912: Changeover switch 913: Low-pass filter 914: Limiter

Claims (6)

In an AC AC power converter that converts an AC power supply voltage into an AC voltage of an arbitrary magnitude and frequency and supplies the AC voltage to an electric motor,
Means for detecting the current of the motor;
Coordinate conversion means for converting a current detection value by this means into a d-axis current parallel to the motor magnetic flux and a q-axis current orthogonal thereto;
Current adjusting means for adjusting the output voltage of the power converter so that the d-axis current and the q-axis current match the d-axis current command and the q-axis current command, respectively;
D-axis current command adjusting means for increasing the motor current by adjusting the d-axis current command when energy is regenerated from the motor to the power converter;
The control apparatus of the alternating current alternating current power converter characterized by having provided. In an AC AC power converter that converts an AC power supply voltage into an AC voltage of an arbitrary magnitude and frequency and supplies the AC voltage to an electric motor,
Means for controlling the output voltage of the power converter based on a d-axis current command parallel to the motor magnetic flux and a q-axis current command orthogonal thereto;
D-axis current command adjusting means for increasing the motor current by adjusting the d-axis current command when energy is regenerated from the motor to the power converter;
The control apparatus of the alternating current alternating current power converter characterized by having provided. In the control apparatus of the AC / AC power converter according to claim 1 or 2,
The AC / AC power converter is capable of emergency operation using an emergency power supply when the AC power supply voltage drops,
A control apparatus for an AC / AC power converter, wherein the motor current is increased by the operation of the d-axis current command adjusting means during emergency operation, and regenerative energy is consumed by the motor. In the control apparatus of the alternating current alternating current power converter as described in any one of Claims 1-3,
The control apparatus for an AC / AC power converter, wherein the electric motor is a synchronous motor. In the control apparatus of the alternating current alternating current power converter as described in any one of Claims 1-3,
The control apparatus for an AC / AC power converter, wherein the electric motor is an induction motor. In the control apparatus of the alternating current alternating current power converter as described in any one of Claims 1-5,
The AC / AC power converter is a direct converter that directly converts an AC power supply voltage into an AC voltage without having an energy buffer.

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