JP4224180B2 - Sensorless self-excited resonance type electromagnetic vibration device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sensorless self-excited resonance type electromagnetic vibration device that conveys a granular material using vibration due to an attractive force of an electromagnet and a restoring force of a spring.
[0002]
[Prior art]
As a control device for a resonance type electromagnetic vibrator for driving an electromagnetic feeder, there is one disclosed in Japanese Patent Laid-Open No. 5-224756. This is a method of detecting and following the frequency at which the phase of the fundamental wave and the third harmonic of the electromagnet current are both 90 °, and performs resonance type electromagnetic vibration control.
[0003]
[Problems to be solved by the invention]
However, this method has a problem of high cost because phase detection is performed for the fundamental wave and the third harmonic.
The problem to be solved by the present invention is to perform vibration control of self-excited resonance type using the electromagnet itself as a distance sensor in the vibration conveying device of the granular material using vibration due to the attractive force of the electromagnet and the restoring force of the spring, The object is to provide a low-cost and high-performance apparatus that enables rapid vibration, rapid stop, and conveyance amount control.
[0004]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, a sensorless self-excited resonance type electromagnetic vibration device of the present invention is the above-described powder conveyance device that vibrates a vibrating body using the attractive force of an electromagnet and the restoring force of a spring. A current sensor and a voltage sensor for detecting a current and a voltage of a current control PWM inverter for energizing a coil of an electromagnet that vibrates a vibrating body, a current signal obtained by the current sensor, and a voltage signal obtained by the voltage sensor The sensorless displacement calculation means for calculating the absolute value through the band pass filter of the carrier frequency, dividing the current signal obtained by the calculation by the voltage signal, and using this as the information amount of the displacement of the vibrating body, a band-pass filter to obtain the amplitude x _Ad vibration by selecting a specific frequency band from the information amount of the displacement, it compares the amplitude x _Ad of the vibration with a predetermined reference value A comparator that obtains a wave voltage, an integration circuit that integrates the output of this comparator to obtain a triangular wave, and a function that calculates the phase of the vibration velocity by shaping the triangular wave generated by this integration circuit into a sine wave of constant amplitude And a carrier speed calculation circuit for differentiating the detected amplitude x _Ad to obtain a vibration speed and calculating an absolute value thereof, and the obtained vibration speed is negatively fed back to the conveyance amount command, and the error is calculated by PID. A PID controller that performs a square root operation on the output of the PID controller, and a multiplier that obtains a product of the square root operation value and the phase of the vibration velocity. A command is given to the current control PWM inverter as a command, and the electromagnet is energized to generate an attractive force.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described.
FIG. 2 shows a means for detecting sensorless displacement of the vibrating body. The current I applied to the electromagnetic coil 22 by the current control PWM inverter 21 includes switching ripple currents of the transistors TR1 and TR2 with a carrier frequency of 10 KHz. It is out. The ripple current, the electromagnet coil ripple voltage E _L , and the distance x between the electromagnet cores are related by the self-inductance L.
[0006]
That is, the general relational expressions are the following two expressions.
| E _L | = 2πfH _L × | I |
f _H : PWM carrier frequency (about 10 kHz)
L ≒ (μ ₀ AN ² / 2x) [H] ··· (Self-inductance)
Here, μ ₀ is 4π × 10 ⁻⁷ [H / m], A is the magnetic pole area [m ² ], and N is the number of coil turns.
[0007]
X is obtained from the above relational expression. Technically, the ripple is extracted by a band pass filter.
x = (μ ₀ AN ² / πf _H ) × (| I | / | E _L |)
∴x∝ | I (BPF) | / | E _L (BPF) |
[0008]
As the execution means, and differential operation of the current detection value I _d, and the absolute value operation (full-wave rectification), to clear the carrier ripple through BPF8 of LPF19 or mechanical resonant frequency near, corresponding to the distance x to the sensorless the x _Ad corresponding to x _d and the amplitude computing detection.
Here, I _S is a current command (for mechanical vibration), and I ₀ is a calculation current command (a constant value of about 5%).
[0009]
The means for controlling the natural vibration of the mechanical system is as follows. When an attraction force F [N] of an electromagnet, a mass M [Kg] of a body to be vibrated, a spring constant K [N / m], a vibration damping coefficient D [N / m / s], and a displacement x [m] It is expressed by the following formula as a formula.
F = M · d ² x / dt ² + D · dx / dt + Kx (1)
[0010]
By transforming this, the following equation is obtained.
FD · dx / dt = M · d ² x / dt ² + Kx (2)
This right side is a continuous oscillation with a constant amplitude. Therefore, F may be controlled so that the left side becomes FD · dx / dt = 0. That is, if the attraction force F of the electromagnet is controlled by the velocity vector phase by an amount that eliminates the vibration damping force, constant amplitude control that resonates with the natural vibration of the mechanical system can be realized.
[0011]
Next, means for linearizing the electromagnet attractive force will be described.
The attractive force F of the electromagnet is non-linear as shown by the following equation.
_{F [N] = (μ 0} AN 2/8) (I / x) 2
[0012]
Basically, it is necessary to linearize the force in order to stabilize the control system. Therefore, if the value of √I is set to the current of the electromagnet for linearization, the force can be linearized with respect to the current as shown in the following equation.
_{F [N] = (μ 0} AN 2/8) (I / x 2)
[0013]
A calculation method for realizing these will be described.
In order to convert the above-mentioned electromagnet attractive force F into a natural vibration vector and linearize it, the calculation of FIG. 3 is performed on the output of the PID 16.
[0014]
FIG. 4 shows a control system improved by the present invention. By the above calculation method, the control system is expressed as a transfer function block diagram shown in FIG. 4, and stable vibration control becomes possible. This open loop transfer function G ₀ is expressed by the following equation:
G ₀ = {PKv (1 + IS) (1 + dS) / IS (1 + TS) (1 + tS) (MS + D)} × (I ₀ / x ₀ ) L ₀
Even with the damping coefficient D = 0, it can be controlled stably by selecting the differential time constant d.
Where P: proportional gain, I: integral time constant, d: derivative time constant, t: noise cut time constant, K _v : vibration speed detection coefficient, L ₀ : reference inductance, x ₀ : reference gap distance, T: speed Detection filter time constant.
[0015]
【Example】
FIG. 1 shows an outline of an embodiment of the present invention. In the figure, 1 is an electromagnet, 2 is a vibrating body, 3 is a spring, 4 is a current transformer (CT), 5 is a sensorless displacement calculator, 6 is a differentiation circuit, 7 is an absolute value calculation circuit, 8 is a bandpass filter, 9 is a conveyance speed calculator, 10 is a differentiation circuit, 11 is an absolute value calculation circuit, 12 is a speed phase calculator, 13 is a comparator, 14 is an integration circuit, 15 is a sine wave shaping circuit, 16 is a PID calculator, 17 Is a square root arithmetic circuit, 18 is a multiplier, 19 is a divider, 20 is a multiplier, 21 is a PWM inverter, 22 is an electromagnet coil, and 23 is a transport amount command circuit.
[0016]
In this embodiment, the I _d which detects the current supplied from the current control inverter 21 in CT4, and an output voltage E _L of the inverter 21, the carrier frequency band through BPF6 and BPF6 'of the carrier frequency of the inverter (approximately 10 kHz) only Then, the absolute value is obtained through the absolute value calculation circuits 7 and 7 ', and the former 19 is divided by the latter by the divider 19 to obtain the displacement x of the vibrating body. Further, the amplitude x _Ad is calculated and detected through the BPF 8 (sensorless detection). Next, the amplitude detection x _Ad is compared with the reference value by the comparator 13, integrated by the integration circuit 14, and converted into a sine waveform by the sine wave shaping circuit 15 to calculate the speed phase. On the other hand, x _Ad is differentiated by the differentiation circuit 10, the absolute value is obtained by the absolute value calculation circuit 11, the conveyance speed is calculated, this is negatively fed back to the conveyance amount command, and the PID calculation control output is obtained by the PID calculator 16. . This square root calculation is performed by the square root calculation circuit 17. A multiplication value of this value and the speed phase is obtained, and this is given to the current control PWM inverter 21 to energize the electromagnet 1.
[0017]
As a result, in the powder vibration transfer device using the vibration caused by the attractive force of the electromagnet 1 and the restoring force of the spring 3, self-excited resonance type vibration control using the electromagnet itself as a distance sensor is performed. A low-cost, high-performance device that enables stopping, transport amount control, etc. can be realized.
[0018]
Next, details of the embodiment of FIG. 1 will be described with reference to the drawings.
FIG. 5 shows details of the transport amount command circuit 23 of FIG. 1, in which 31 is a voltage setting device, 32 is a voltage dividing circuit, 33 is a high-speed / low-speed switch, and 34 is an amplifier.
[0019]
FIG. 6 shows details of the PID arithmetic circuit 16 of FIG. 1, in which 35 is a gain adjuster, 36 is a differentiation / integration circuit, and 37 is a start / stop switch.
[0020]
FIG. 7A shows details of the square root arithmetic circuit 17 of FIG. 1, and FIG. 7B is a characteristic diagram showing the relationship between the input voltage and the output voltage.
[0021]
FIG. 8 shows details of the speed phase calculation circuit 12 and the conveyance speed calculation circuit 9 of FIG. In the figure, reference numeral 38 denotes a low-pass filter for removing noise.
[0022]
FIG. 9 shows the details of the sensorless displacement calculation circuit 5 of FIG. 1, in which 39 is an amplifier for amplification and ripple removal.
[0023]
Next, an oscillograph waveform of the experimental results is shown.
FIG. 10 shows a comparison between a sensorless calculation detection waveform and a conventional acceleration sensor waveform, and it can be seen that the present invention based on sensorless calculation provides better characteristics with less noise.
[0024]
FIG. 11 shows the gap _xd and current I during no-load operation. The phase difference between _xd and I is 90 °, indicating that the current is fixed to the vibration velocity phase.
[0025]
FIG. 12 shows the response during low-load operation (low speed 0.2 mm, high speed 2 mm). It can be seen that the response speed and the stability of the control are good when the speed command is suddenly changed.
[0026]
If the above-described analog method is digitized, PID, square root calculation, multiplier, sine wave shaping, LPF, BPF, etc. can be performed at low cost. However, the sensorless displacement calculation is analog.
[0027]
【The invention's effect】
As described above, according to the present invention, the self-excited resonance type vibration control using the electromagnet itself as a distance sensor is performed in the granular material vibration conveyance device using the vibration caused by the attractive force of the electromagnet and the restoring force of the spring. It is possible to realize a low-cost and high-performance apparatus that enables rapid vibration, rapid stop, and conveyance amount control.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an outline of an embodiment of the present invention.
FIG. 2 is a block diagram showing an outline of a current control PWM inverter of the present invention.
FIG. 3 is a block diagram of natural vibration vectorization and linearization calculation in the present invention.
FIG. 4 is a transfer function block diagram of a control system of the present invention.
FIG. 5 is a circuit diagram showing details of a carry amount command circuit of the present invention.
FIG. 6 is a circuit diagram showing details of a PID arithmetic circuit of the present invention.
7A and 7B show details of the square root arithmetic circuit of the present invention, in which FIG. 7A is a circuit diagram, and FIG. 7B is a characteristic diagram showing a relationship between input and output voltages.
FIG. 8 is a circuit diagram showing details of a speed phase calculation circuit and a conveyance speed calculation circuit of the present invention.
FIG. 9 is a circuit diagram showing details of a sensorless displacement calculation circuit of the present invention.
FIG. 10 is a sensorless calculation detection waveform and a conventional acceleration sensor waveform diagram.
FIG. 11 is a characteristic diagram showing the relationship between the gap and current during no-load operation.
FIG. 12 is a characteristic diagram showing a response during no-load operation.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Electromagnet, 2 to-be-vibrated body, 3 spring, 4 current transformer (CT), 5 sensorless displacement calculator, 6, 6 'band pass filter (BPF), 7, 7' absolute value calculation circuit, 8 band pass filter ( BPF), 9 Transport speed calculator, 10 Differentiation circuit, 11 Absolute value calculation circuit, 12 Speed phase calculator, 13 Comparator, 14 Integration circuit, 15 Sine wave shaping circuit, 16 PID calculator, 17 Square root calculation circuit, 18 Multiplier, 19 Divider, 20 Multiplier, 21 PWM inverter, 22 Electromagnetic coil, 23 Carrying amount command circuit, 31 Voltage setter, 32 Voltage divider circuit, 33 High speed / low speed changeover switch, 34 Amplifier, 35 Gain adjuster, 36 differentiation / integration circuit, 37 start / stop switch, 38 low pass filter (LPF), 39 amplifier

Claims (1)

In the vibration conveying device of the granular material that vibrates the vibrating body using the attractive force of the electromagnet and the restoring force of the spring,
A current sensor and a voltage sensor for detecting a current and a voltage of a current control PWM inverter for energizing a coil of an electromagnet for exciting the vibrating body;
The absolute value of the current signal obtained by the current sensor and the voltage signal obtained by the voltage sensor is calculated through a band-pass filter of a carrier frequency, and the current signal obtained by the calculation is divided by the voltage signal. , A sensorless displacement calculation means using this as an information amount of the displacement of the vibrating body,
A bandpass filter that selects a specific frequency band from the information amount of the displacement to obtain an amplitude x _Ad of vibration;
A comparator that compares the amplitude x _Ad of the vibration with a predetermined reference value to obtain a square wave voltage;
An integration circuit that obtains a triangular wave by integrating the output of the comparator;
A function generator that shapes the triangular wave generated by this integration circuit into a sine wave of constant amplitude and obtains the phase of the vibration speed,
A conveyance speed calculation circuit for differentiating the detected amplitude x _Ad to obtain a vibration speed and calculating an absolute value thereof;
A PID controller that negatively feeds back the obtained vibration speed to the conveyance amount command and calculates the error by PID,
A square root calculator for performing a square root calculation of the output of the PID controller;
A multiplier for obtaining a product of the square root operation value and the phase of the vibration speed;
A sensorless resonance type electromagnetic vibration device characterized in that an output of the multiplier is given as a current command to a current control PWM inverter to energize an electromagnet to generate an attractive force.

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