JPS6142518B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for a commutatorless motor using a static electric valve such as a thyristor.

The commutatorless motor is driven by an inverter that can switch the ignition thyristor arm based on the output of the rotational position detector, and is expected to provide performance similar to that of a DC motor. In order to overcome such peculiarities of commutatorless motors, various considerations are required.

As is well known, in a DC motor, in order to switch the direction of torque, it is necessary to reverse the direction of the motor current or the direction of the field current, which is useful in steel rolling mills and paper machines that require rapid acceleration and deceleration. In this case, the armature current reversal method is usually used.

Even in non-commutated motors, the armature current reversal method is preferable, and the armature current can be reversed by controlling the firing phase of the inverter. Before and after switching the torque direction, control is required to once reduce the DC current of the forward converter to zero and then switch the ignition phase of the reverse converter. However, if the firing phase is switched while a direct current is flowing, the pair of upper and lower thyristor arms of the inverter fire simultaneously, causing a so-called commutation failure in which the circuit is short-circuited.

In order to reduce such a direct current to zero, it is necessary to deepen the firing phase angle of the forward converter and regenerate the energy stored in the circuit. After the ignition phase angle, which has been reduced once, is switched in the torque direction, it takes time to restore it to a value equivalent to the motor voltage, so it takes time before the DC current starts flowing again.

Since the period in which the current is zero is the period in which the torque is zero, if the period is too long, the speed responsiveness of the device will deteriorate, which is not preferable.

FIG. 1 is a block diagram of a conventional control device for a commutatorless motor. In FIG. 1, 1 is an AC power supply, 2 is a forward conversion device consisting of a thyristor arm,
3 is a flat sliding actor, 4 is a thyristor arm U,
5 is a synchronous motor, 6 is a rotational position detector, 7 is a speed generator, 8 is a current transformer that transforms direct current, and 9 is a forward conversion device consisting of V, W, X, Y, and Z. 2 an ignition circuit, 10 an ignition circuit for the inverse converter 4, 11 a logic circuit that receives a signal from the rotational position detector 6 and determines the ignition arm of the inverse converter 4, 12 a speed setting device, and 13 an ignition circuit for the inverse converter 4; A speed controller 14 is a torque direction switching circuit that determines power running mode or regeneration mode based on the output of the speed controller 13;
15 is an absolute value circuit, and 16 is a current controller.

FIG. 2 shows the firing thyristor arm of the inversion device 4. In Figure 2, (1) is the induced voltage of the motor, (2) is the distributor signal for power running, (3) is the communication arm during power running, (4) is the distributor signal for regeneration, (5) indicate the flow arms during regeneration. The phase difference βM during power running and the phase difference βB during regeneration correspond to the phase control angle of the inverse conversion device.

FIG. 3 is a vector diagram showing the phase relationship between the induced voltage of the rotor synchronous motor 5 and the armature current.
βM during power running gives the commutation margin angle of the thyristor arm, and normally βM during power running and βB during regeneration are selected to be the same. Forward conversion device 2
The DC voltage at the output terminal of is approximately 1.35 x (motor voltage) COSβM and 1.35 x (motor voltage), ignoring commutation drop and resistance drop voltage.
Since COSβB is obtained, regeneration and power running modes can be controlled with the same DC voltage. βB=60゜βM=60
It is also known that if the angle is selected, the same rotational position detector 6 can be used during power running regeneration.

FIG. 4 is a characteristic diagram of the ignition circuit 9 of the forward conversion device 2. The signal x of the current controller 16 becomes the input signal of the ignition circuit 9, shown as a phaser input. This signal x causes the ignition phase angle of the ignition circuit 9 to vary from 150° to 0°. This phase characteristic has a relationship of X∝COS (phase control angle), and the DC voltage of the forward converter 2 changes linearly with respect to the signal x. Ignoring the commutation drop and resistance drop voltage of each part related to this DC voltage, the signal x is determined by the DC voltage, so it must be set corresponding to the base speed during power running, the base speed and top speed during top speed regeneration. can do.

FIG. 5 is a characteristic diagram showing the relationship between the rotational speed of the synchronous motor 5 and the DC voltage. In FIG. 5, since the excitation is constant up to the base speed, the DC voltage changes in proportion to the speed, but from the base speed up to the top speed, the field is weakened to suppress the rise in DC voltage. In any case, since the pattern of the field current that changes depending on the speed is set, the DC voltage corresponding to the speed and the value of the signal x corresponding thereto are uniquely determined.

FIG. 6 is a block diagram showing the apparatus shown in FIG. 1 in more detail, and the same reference numerals indicate the same parts.

In the speed controller 13, 20 is a point that matches the speed reference from the speed setter 12 and the detected speed from the speed generator 7, 21 is an operational amplifier that amplifies the signal from the point 20, and 31 is the SC output of the speed controller 13. A torque signal discrimination circuit 32 detects that the speed controller 13 is negative.
This is a torque signal discrimination circuit that detects that the SC output is positive. Reference numeral 33 denotes a flip-flop which is set and reset by the signals from the torque signal discrimination circuits 31 and 32, respectively, and generates a positive torque signal _M1 and a negative torque signal _B1 from the Q output and the output, respectively. 30 is a zero current detection circuit that detects the zero of the direct current of the forward converter 2 via the current transformer 8; 34 and 35 are AND circuits; and 36 are AND circuits 34 and 3.
A flip-flop that sets and resets with the output _of
B ₁ ) becomes 1 and the zero current detector 30 detects zero of the DC current, the power running signal M (or regeneration signal B) is set to 1. The power running signal M and the regeneration signal B are applied to a logic circuit 11, which determines the firing thyristor arm of the inverter 4.

In the absolute value circuit 15, 22 is an operational amplifier for code conversion, 23 and 24 are switches, and 25 is a meeting point for the signals from the switches 23 and 24. In the absolute value circuit 15, the switch 23 or 24 is turned on by the positive torque signal M ₁ (or the negative torque signal B ₁ ), and always outputs a signal with a constant sign.

In the current controller 16, 26 is a point where the signal from the absolute circuit 15 and the detected current from the converter 8 are matched, 27 is an operational amplifier, and 28 is a capacitor that forms an integrator together with the operational amplifier 27.
9 is a switch provided between the input and output terminals of the operational amplifier 27. 37 and 38 are AND circuits. 39 is an OR circuit, and speed controller 1
A positive torque signal is generated by reversing the SC output of 3.
If a period is found in which the power running signal M (or regeneration signal B) is not reversed even though M ₁ (or negative torque signal B ₁ ) is reversed, it is a signal indicating the occurrence of a short circuit.
Generates EL.

When the signal EL occurs, the current controller 16
Since the switch 29 inside is turned on and the signal x of the current controller 16 becomes zero, the ignition phase angle of the forward converter 2 is narrowed down to 150°. That is, when a short circuit in the current controller 16 is detected, the ignition phase is narrowed down to 150 degrees, and when the switching of the torque direction is completed, the current controller 1
To prevent the signal x of No. 6 from fluctuating unnecessarily and causing an overcurrent.

FIG. 7 is a waveform diagram illustrating the operation of the device shown in FIG. 6.

In Fig. 7, (1) is the speed command, which is the output of the speed setting device 12, and at time t ₀ , the speed changes from 440 rpm to 400 rpm.
Indicates that the settings have been changed. (2) indicates the actual speed of the synchronous motor 5, and indicates that the speed is set to 400 rpm after time T has elapsed. (3) is the SC output of the speed controller 13, which is inverted again from negative to positive at time _t1 . (4) is the DC voltage output from the forward converter 2. (5) is the direct current of the forward converter 2, which becomes zero at time _t2 and starts flowing again at time _t3 . (6) is a negative torque signal B ₁ , (7) is a positive torque signal M ₁
Both switch when the SC output is inverted. (8) is the regeneration signal B, and (9) is the power running signal M, which switches from 0 to ₁ at time t2 when the DC current becomes zero. (10) is the short circuit signal EL, which occurs between time t ₁ and t ₂ . The forward conversion device 2 lowers the output so that the regenerative current flows sufficiently from time _t0 , so when the speed of the synchronous motor 5 decreases to 400 rpm and the SC output of the speed controller 13 reverses the polarity at _t1 , the phase changes. The control angle is forcibly set to 150°. Therefore, the forward converter 2 sets the DC voltage to the maximum negative voltage and rapidly reduces the DC current. When the direct current becomes zero at time _t2 , the short circuit of the amplifier 27 of the current controller 16 is opened, so that the signal x increases. Since the current controller 16 shows the response of an integral system, the signal x
It takes time to reach the power mode signal of 400 rpm, and the DC current finally begins to flow at time _t3 .

i.e. 100-150 m from time t ₂ to time t ₃
The period s is a no-current period in which the torque is zero and there is no control.

Therefore, the speed settling time T was also about 0.4 seconds, and the response characteristics of the device were unsatisfactory.

The present invention was made in order to solve the conventional problems as described above, and provides control of a non-commutated motor that can improve response characteristics by reducing the period during which the direct current of the forward converter is zero. The purpose is to provide equipment.

An embodiment of the present invention will be described below with reference to the drawings. FIG. 8 is a block diagram showing one embodiment of the present invention.

In FIG. 8, 41 is a level circuit for the forcing signal F, 42 is a timing circuit for the forcing signal F, 43 is a switch, and the timing circuit 4
When the output signal F of 2 is generated, it turns on,
The signal EF1 from the level circuit 41 is guided to the junction point 26.

In the level circuit 41, 44 is a field weakening command, which is input to a matching point 45 and is a signal for subtracting the signal of the speed generator 7 so as to suppress an increase in the signal EF0 in the field weakening region. signal
EF0 is connected via an operational amplifier 46 and a switch 48 for polarity inversion of the signal, and via a switch 47 to a bias setter 58 at a junction point 49.
By adding it to the bias signal BI of , the signal EF1 is obtained. The bias signal BI is provided in accordance with the phase characteristics (shown in FIG. 4) of the ignition circuit 9 of the forward converter 2, and for example, when the speed of the synchronous motor 5 is zero, , since the induced voltage of the synchronous motor 5 becomes zero, the DC voltage of the forward converter 2 also becomes zero, and the phase control angle of the forward converter 2 becomes
It becomes 90°. At this time, the signal X is not zero, and a signal of the level shown in FIG. 4 is required, so the bias signal BI is adjusted in accordance with this phase signal level. The signals EF0 and EF1 are given characteristics as shown in FIGS. 9 and 10, respectively, and are input to the ignition circuit 9 via the current controller 16 based on the speed of the synchronous motor 5.
A phase control angle signal is generated to control the forward conversion device 2.

In the timing circuit 42, 50 is a polarity inversion logic, 51 is a differentiation circuit, 53 is a current detection circuit, 5
4 is a differential circuit, and 52 is a flip-flop.
When the short circuit signal EL from the OR circuit 39 becomes zero,
Since the output of the polarity inversion logic 50 becomes high and a differential pulse is output from the differentiating circuit 51, the flip-flop 52 is set and the Q output becomes 1.
When direct current starts flowing through the inverter 4, the current transformer 8
The current detection circuit 53 detects this through the differential circuit 54, and a pulse is outputted from the differentiating circuit 54 to reset the flip-flop 52, so that its Q output becomes 0. 55 is a monostable multi, 56 is a polarity reversal theory, and 57 is an AND circuit. monostable multi 55
The width of the pulse Z only needs to be sufficiently larger than the turn-off time of the thyristors in the forward conversion device 2 and the inverse conversion device 4, and is set to, for example, several milliseconds. That is, when the short circuit signal EL becomes zero and the set time of the monostable multi 55 has elapsed, the forcing signal F output from the AND circuit 57 becomes 1. Thereafter, when the current is detected by the current detection circuit 53 via the current transformer 8, the flip-flop 52 is reset and the AND circuit 57 is closed, so that the forcing signal F becomes zero.

FIG. 11 is a waveform diagram illustrating the operation of the device shown in FIG. 8. In FIG. 11, at time _t0 , the speed command is changed from 440 rpm to 400 rpm. point in time
At t ₁ , the SC output of the speed controller 13 is again inverted to negative, and the input and output of the current controller 16 are shorted by the switch 29 . At time _t2 , the current in forward converter 2 becomes zero.

In FIG. 11, 11 is a pulse Z outputted from the monostable multi 55, and the pulse width is set to be several milliseconds from time t ₂ to time t ₄ . point in time
At _t4 , the pulse Z becomes 0, and the inhibition of the AND circuit 57 is released, so the forcing signal F is generated and the signal EF1 is output via the switch 43.
to the meeting point 26. Therefore, the current controller 16 controls the DC voltage of the forward converter 2 to be the same as when the synchronous motor 5 is in power running, so that at time _t5 , the DC current starts flowing and the flip-flop 52 is reset. The forcing signal F disappears.

Therefore, the time from time t ₄ to time t ₅ can be very short, for example, the zero current period from time t ₂ to time t ₅ can be shortened to about 10 msec, so that the speed settling of the synchronous motor 5 can be reduced. The time T is also improved to about 0.2 seconds, and the response is almost the same as that of the thyristor Leonard driven by a DC motor.

As explained above, according to the present invention, the responsiveness of a commutatorless motor is significantly improved.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a conventional control device, Fig. 2 is a waveform diagram showing the operation of the firing thyristor arm of the inverter, Fig. 3 is a vector diagram showing the phase relationship of voltage and current of a commutatorless motor, Figure 4 is a characteristic diagram of the ignition circuit of the forward converter, Figure 5 is a characteristic diagram showing the relationship between motor speed and DC voltage, Figure 6 is a detailed block diagram of the device shown in Figure 1, and Figure 7. 6 is a waveform diagram illustrating the operation of the device shown in FIG. 6, FIG. 8 is a block diagram illustrating an embodiment of the present invention, FIGS. 9 and 10 are characteristic diagrams illustrating the operation of the following circuit, and FIG.
The figure is a waveform diagram illustrating the operation of the apparatus shown in FIG. 8. 2... Forward conversion device, 4... Inverse conversion device, 5...
Synchronous motor, 6... Rotational position detector, 7... Speed generator, 8... Current transformer, 9, 10... Ignition circuit,
11...Logic circuit, 12...Speed setter, 13...
... Speed controller, 14 ... Torque direction switching circuit, 15 ... Absolute value circuit, 16 ... Current controller, 41 ... Level circuit, 42 ... Timing circuit, 43 ... Switch. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A rotational position detector that detects the rotational position of the electric motor, a stationary inverter that controls the voltage applied to the armature winding of the motor, and an AC power source connected between the inverter and the inverter, Control of a non-commutator motor, comprising a static forward converter that converts AC voltage from the AC power source into DC voltage, and switches the ignition logic of the inverse converter in accordance with the direction of torque required for the motor. In the device, a forcing level is calculated from a speed detection signal detected from the electric motor and a field weakening command for the electric motor, and has a level value corresponding to a DC voltage of a forward conversion device during power running and regeneration of the electric motor. A forcing level circuit that generates a signal is energized and the direct current begins to flow after a time from when the direct current of the forward converter becomes zero to when the turn-off of the inverse converter is completed when switching the torque direction. a timing circuit that generates a phasing timing signal such that the phasing level signal is deenergized when the phasing timing signal is detected; and a switch that passes the phasing level signal in accordance with the phasing timing signal; 1. A control device for a commutatorless motor, characterized in that a phase control angle of a firing control circuit of the forward conversion device is controlled to a phase control angle corresponding to the forcing level signal using a shifting level signal.