JPH0632571B2 - Power supply for ultrasonic motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to an ultrasonic motor power source for driving an ultrasonic motor.

(Prior Art) In order to drive an ultrasonic motor, a two-phase AC power supply for supplying electric power of two phases different from each other by π / 2 rad is required for two ceramic vibrators.

As this two-phase AC power supply, a device that uses two separately-excited inverters to supply alternating currents of two different phases to the two ceramic vibrators is considered.

(Problems to be Solved by the Invention) However, when the above-mentioned conventional device is used, the oscillation frequency _{i of the} inverter circuit is adjusted to the electrical resonance frequency by adjusting the gap or the number of turns of the transformer at a certain temperature. _{Even if E} and the oscillation frequency _o are matched, the capacitance C of the ceramic oscillator largely changes depending on the temperature, so that the oscillation frequency _{i of the} inverter circuit and the electrical resonance frequency _{E of the} circuit are easily deviated by the temperature. For this reason, there is a problem that it becomes a capacitive or inductive load, heat generation of the switching element increases, and the switching element is destroyed.

The present invention has been made in view of the above problems, and an object thereof is to provide a power supply for an ultrasonic motor in which a switching element of an inverter circuit is not heated and destroyed.

[Structure of Invention]

(Means for Solving Problems) A power supply for an ultrasonic motor according to a first aspect of the present invention is a DC power supply, a self-excited inverter circuit connected between the DC power supply and the first ceramic vibrator, and The self-excited inverter circuit comprises a separately-excited inverter circuit connected between a DC power source and a second ceramic oscillator, and the self-excited inverter circuit has an oscillation frequency set by an inductance in the self-excited inverter circuit and a capacitance of the ceramic oscillator. The separately excited inverter circuit oscillates and oscillates at the oscillation frequency of the self-excited inverter circuit.

An ultrasonic motor power supply according to a second aspect of the present invention includes a DC power supply, a self-excited inverter circuit connected between the DC power supply and the first ceramic vibrator, the DC power supply and the second ceramic vibrator. And a correction circuit connected to the self-excited inverter circuit and the self-excited inverter circuit, wherein the self-excited inverter circuit includes an inductance in the self-excited inverter circuit and a ceramic oscillator. The oscillation frequency is set by the capacitance and oscillates, and the separately excited inverter circuit oscillates at the oscillation frequency of the self-excited inverter circuit,
The correction circuit is capable of changing the inductance of the inverter circuit according to the vibration amount of the first and second ceramic vibrators.

(Operation) In the first invention, the oscillation frequency of the self-excited inverter is set by the inductance of the self-excited inverter and the capacitance of the first ceramic oscillator to vibrate the first ceramic oscillator. Further, the separately excited inverter is oscillated at the same frequency according to the oscillation frequency of the self-excited inverter to vibrate the second ceramic oscillator.

In a second aspect based on the first aspect, the inductance is adjusted according to the vibration amount of the first and second ceramic oscillators to change the oscillation frequency of the self-excited inverter, and
The vibration amount of the first and second ceramic vibrators is set to a certain fixed amount.

(Embodiment) An embodiment of an ultrasonic motor power source will be described below with reference to the drawings.

In the figure, reference numeral 1 is a driving DC power source, and a self-excited inverter circuit 2 for Sin wave output is connected to the DC power source 1.

In this self-excited inverter circuit 2, the positive electrode of the DC power supply 1 is connected to the center of the primary winding 4 of the transformer 3, and the primary winding 4
One of the first primary windings 5 is connected to the negative electrode of the DC power supply 1 via the collector / emitter of the first transistor 6 as a switching element, and the other second secondary winding of the primary winding 4 of the transformer 3 is connected. The primary winding 7 is connected to the negative electrode of the DC power supply 1 through the collector / emitter of the second transistor 8 as a switching element. Further, from the positive electrode of the DC power supply 1 to the bases of the first transistor 6 and the second transistor 8, the self-excited inverter circuit 2 is provided.
The start-up resistors 9 and 10 for starting up are connected. Furthermore, the transistors 6 and 8 are connected to the secondary winding of the transformer 3.
Electrical resonance frequency set by the inductance L of 11 and the capacitance C of the first ceramic oscillator 12 of the ultrasonic motor Winding for switching element of transformer 3 for operating in
One end of 13 is connected to the base of the first transistor 6, and the other end is connected to the base of the second transistor 8 of the ultrasonic motor.

And the secondary winding of the transformer 3 of the self-excited inverter circuit 2.
A first ceramic oscillator 12 is connected to 11.
At this time, the resonance frequency _E determined by the inductance L of the secondary winding 11 and the like and the capacitance C of the first ceramic oscillator 12 becomes equal to the oscillation frequency _o peculiar to the first ceramic oscillator 12. Adjust the gap or the number of turns of the transformer 3.

A separately excited inverter circuit 14 for outputting Cos waves is connected to the DC power supply 1. In the separately excited inverter circuit 14, the positive electrode of the DC power supply 1 has a primary winding 16 of a transformer 15.
The first primary winding of one of the primary windings 16 connected to the center of
17 to the first transistor 18 as a switching element
Is connected to the negative electrode of the DC power supply 1 via the collector / emitter of the above, and the collector / emitter of the second transistor 20 as a switching element is connected from the other second primary winding 19 of the primary winding 16 of the transformer 15. After that, it is connected to the negative electrode of the DC power supply 1. The output terminals of the phase circuit 21 connected to both ends of the switching element winding 13 are connected to the bases of the first transistor 18 and the second transistor 20, respectively.

And the secondary winding of the transformer 15 of the separately excited inverter circuit 14.
A second ceramic oscillator 23 is connected to 22.
At this time, the electric resonance frequency _E determined by the inductance L of the secondary winding 22 and the capacitance C of the ceramic oscillator 23 is transformed so as to be equal to the intrinsic oscillation frequency _{o of} the second ceramic oscillator 23. Adjust the gap or the number of turns in device 15.

In addition, the first ceramic oscillator 12 and the ceramic oscillator 23
And one end of the secondary winding 11 of the transformer 3 and one end of the secondary winding 22 of the transformer 15 are connected to have a common potential.

Further, a correction circuit 24 is connected to the first and second ceramic vibrators 12 and 23. The correction circuit 24 captures the vibration amounts of the ceramic vibrators 12 and 23 as a voltage, and is connected to a comparison circuit 25 having a reference voltage for comparing the vibration amounts of the ceramic vibrators 12 and 23.
A correction DC power supply 26 whose voltage is varied by the comparison circuit 25 is connected to the.

The correction DC current 26 is applied to the correction winding of the transformer 3.
27, the compensation winding 28 of the transformer 15, and these compensation windings 27, 2
An inductor 29 for removing the AC component of 8 is connected in series.

Next, the operation of the above embodiment will be described.

First, when a voltage is applied from the DC power supply 1, a base current flows through the base of the first transistor 6 or the second transistor 8 via the starting resistor 9 or the starting resistor 10.
One of the transistors turns on. For example, if the first transistor 6 is first turned on, a current flows from the DC power supply 1 through the path of the first transistor 6 of the first primary winding 5. As a result, a voltage is induced in the secondary winding 11, and the inductance L of the secondary winding 11 and the like and the capacitance C of the first ceramic oscillator 12 cause the secondary side circuit of the transformer 3 to oscillate. When the current of the secondary side circuit is in the opposite direction, the switching element winding 13 has a second
A current flows in the direction of the base of the transistor 8, and the second transistor 8 turns on and the first transistor 6 turns off. Thereby, the DC power supply 1, the first primary winding 5,
The current flowing through the path of the first transistor 6 flows through the path of the DC power supply 1, the second primary winding 7, and the second transistor 8. Therefore, the directions of the voltages induced in the secondary winding 11 are opposite. Then, these operations are repeated. That is, it is determined by the inductance L of the secondary winding 11 and the like and the capacitance conductance C of the first ceramic vibrator 12. At the electrical resonance frequency _E obtained in step S1, a current is alternately passed from the switching element winding 13 to the bases of the first transistor 6 and the second transistor 8 to alternately switch the first transistor 6 and the second transistor 8. Turns on and off, induces an alternating current in the secondary winding 11 of the self-excited inverter circuit 2, and always has an electrical resonance determined by the inductance L of the secondary winding 11 of the transformer 3 and the capacitance C of the ceramic vibrators 12 and 23. The first ceramic oscillator 12 is oscillated at the frequency _E.

Further, when a voltage is induced in the switching element winding 13, the separately excited inverter circuit 14 is caused to form a waveform advanced by π / 2 rad at the same frequency as the self-excited inverter circuit 2 from the phase circuit 21 to the first transistor 18 and A base current is alternately applied to the base of the second transistor 20 to alternately turn on the transistors 18 and 20. Then, if the first transistor 18 is turned on first, a current flows from the DC power supply 1 through the path of the first primary winding 16 and the first transistor 18. Next, a base current is given to the base of the second transistor 20 to turn on the second transistor 20, and
Then, the base current of the transistor 18 is eliminated and the first transistor 18 is turned off. As a result, the current flowing in the path of the DC power supply 1, the first primary winding 17, and the first transistor 18 flows in the path of the DC power supply 1, the second primary winding 19, and the second transistor 20. That is, the separately excited inverter circuit
At 14, a waveform advanced by π / 2 rad from the self-excited inverter circuit 2 is formed.

In the correction circuit 24, the vibration amount when the ceramic oscillators 12 and 23 are respectively vibrating at the electrical resonance frequency _E determined by the inductance L of the secondary windings 11 and 12 and the capacitance C of the ceramic oscillators 12 and 23. Is used as a voltage to compare with the reference voltage in the comparison circuit 25 in the comparison circuit 25, the difference between the oscillation frequency _o and the actual frequency is obtained, and the comparison circuit 25 controls the correction current power supply 26 according to the difference, The DC current flowing through the winding 27 and the correction winding 28 is adjusted.
Then, the magnetic field strength of the correction winding 27 and the correction winding 28 is changed to correct the inductance L of the secondary windings 11 and 22,
1st and 2nd ceramic oscillators 12,2 due to temperature change
Even if the capacitance C of 3 changes, the electrical resonance frequency
_E is always set to be the oscillation frequency _o peculiar to the first and second ceramic vibrators 12 and 23 or the vibration amount required for practical use. Although the multivibrator type inverter circuit using two switching elements is used in the embodiments shown in FIGS. 1 and 2, a blocking type inverter circuit using one switching element may be used.

In the embodiment, the self-excited inverter circuit 2 is used for sine wave output and the separately excited inverter circuit 14 is used for cos wave output. However, the self-excited inverter circuit 2 is used for cos wave output, π / 2r.
It is also possible to use a separately-excited inverter circuit 14 for outputting a sine wave by the phase circuit 21 that creates a waveform delayed by ad.

〔The invention's effect〕

According to the first aspect of the present invention, the oscillation frequency of the inverter circuit is determined by the inductance of the inverter circuit and the capacitance of the ceramic vibrator, and the switching element is actuated, so that the capacitance of the ceramic vibrator always changes even when the temperature changes. Since an alternating current equal to the oscillation frequency flows, the load does not become an inductive or capacitive load, and it is possible to prevent overheating and destruction of the switching element.

According to the second invention, since the inductance is corrected by the correction circuit according to the vibration amount of the ceramic vibrator and the electric resonance frequency and the oscillation frequency of the ceramic vibrator are matched, the capacitance of the ceramic vibrator changes with temperature. Even with a ceramic oscillator, the amount of vibration is always the highest or the amount that is practically necessary.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of a power source for an ultrasonic motor,
FIG. 2 is a circuit diagram of the same as above. 1 ... DC power supply, 2 ... Self-excited inverter circuit, 12 ...
1st ceramic oscillator, 14 ... Separately excited inverter circuit, 23 ... 2nd ceramic oscillator, 24 ... Correction circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-60-170473 (JP, A) JP-A-59-65418 (JP, A) Actually opened 63-4191 (JP, U) Actually opened 57- 39685 (JP, U)

Claims (2)

[Claims] 1. A DC power supply, a self-excited inverter circuit connected between the DC power supply and the first ceramic resonator, and another connected between the DC power supply and the second ceramic resonator. The self-excited inverter circuit oscillates with an oscillation frequency set by the inductance in the self-excited inverter circuit and the capacitance of the ceramic resonator, and the self-excited inverter circuit oscillates. An ultrasonic motor power supply characterized by being oscillated by a. 2. A DC power supply, a self-excited inverter circuit connected between the DC power supply and the first ceramic vibrator, and another connected between the DC power supply and the second ceramic vibrator. The self-excited inverter circuit includes a self-excited inverter circuit and a correction circuit connected to the separately-excited inverter circuit, and the self-excited inverter circuit sets an oscillation frequency by an inductance in the self-excited inverter circuit and a capacitance of a ceramic resonator The separately-excited inverter circuit oscillates at the oscillation frequency of the self-excited inverter circuit, and the correction circuit can change the inductance of the inverter circuit according to the vibration amount of the first and second ceramic oscillators. The power supply for ultrasonic motors characterized in that