JPS58267B2 - Atsudentransnoheiretsukudohouhou - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for parallelizing and driving piezoelectric transformers.

In general, a piezoelectric transformer generates mechanical distortion by applying an electric field to the driving part, converts the mechanical distortion into voltage in the power generation part, and obtains a continuous sine wave output voltage. It performs a boosting action during mechanical-electrical energy conversion.

Therefore, since mechanical vibration is involved in the operation, it is difficult to manufacture a large one. Therefore, in order to obtain a relatively large output power, it is necessary to connect two or more piezoelectric transformers in parallel. is normal.

In addition, piezoelectric transformers have high output impedance, so
Voltage regulation is poor, and when the load approaches open circuit, the output voltage increases, leading to electrical discharge, combustion of surrounding parts, and even damage to the piezoelectric transformer.

In view of the above points, an object of the present invention is to provide a novel method for driving piezoelectric transformers in parallel, which eliminates the above-mentioned drawbacks.

The present invention utilizes the fact that the phase of the output voltage of a piezoelectric transformer is determined by the phase of the drive voltage, and the piezoelectric transformers connected in parallel are controlled to have an appropriate phase difference by a phase control means operated by a feedback signal. The device is characterized in that a high output voltage stabilized at a desired value is obtained by driving the output voltage.

Hereinafter, an embodiment in which two piezoelectric transformers are used will be described in detail with reference to the drawings.

In FIG. 1, reference numerals 1 and 2 are piezoelectric transformers. The piezoelectric transformer 1 has drive electrodes 11 and 12 directly connected to a drive power source 3, and the piezoelectric transformer 2 has drive electrodes 21 and 22 connected via a phase control means 6. and is connected to the drive power source 3.

In this specification, for convenience of explanation, a piezoelectric transformer that is connected to a drive power source via a phase control means, such as the piezoelectric transformer 2 described above, will be referred to as a sub-voltage transformer, and a transformer that is not connected to a drive power source will be referred to as a main piezoelectric transformer.

Each output electrode 13.2 of the piezoelectric transformer 1゜2
3 are commonly connected and connected to the output terminal 7 via a voltage doubler rectifier circuit 4 consisting of two diodes 41 and 42.

A detection resistor 5 is inserted between the output terminal 7 and ground, and an electric signal e proportional to the output voltage appearing at the output terminal 7 is fed back to the phase control means 6.

Now, if we use piezoelectric transformers 1 and 2 with the same characteristics, and let their respective output voltages be El and E2, we can obtain The relationship with the voltage EO (=E1+E2) is as shown in FIG.

That is, when the phase difference φ is 0, that is, the piezoelectric transformer 1
, 2 are in phase, E
1=E2, and E0 becomes "2E1".

Furthermore, when the phase difference φ is "T/2", that is, when the phase difference between the respective voltages that drive the piezoelectric transformers 1 and 2 is half the period T of the drive voltage, E1=-E2 and E0 becomes "0". "Become.

This means that the phase difference φ of the drive voltage is “0” to “T/2”.
It is shown that the value of the voltage E0 obtained by superimposing each output voltage can be set to an arbitrary value between "0" and "2E1" by setting the value to an appropriate value between "0" and "2E1".

Therefore, according to this principle, in the parallel drive of the above embodiment, if the phase control means 6 appropriately adjusts the voltage phase of the power supply 3 according to the electric signal e fed back, the respective output voltages can be obtained by superimposing them. The magnitude of voltage E0 can be set to a desired value.

The phase control means 6 may have any structure as long as it can function as described above.

For example, a system configured by combining reactance elements such as coils and capacitors with control elements such as transistors and ICs.
A controllable phase shifter that can adjust the amount of phase shift using a control signal, and a control signal that compares the feedback electric signal e with a preset value and supplies a control signal corresponding to the error to the controllable phase shifter. A configuration consisting of an error detection circuit is conceivable.

When the electrical signal e is larger than the set value, the amount of phase shift is controlled so that the phase difference approaches "T/2",
In addition, if the electrical signal e is smaller than the set value, if the amount of phase shift is controlled so that the phase difference approaches "0" and the operation is made so that the electrical signal e and the set value are equal, the output terminal The value of the rectified output voltage appearing at 7 is stabilized to a value determined by the setpoint.

In this case, it goes without saying that if the set value can be adjusted, a stabilized output voltage of a desired value can be obtained.

In the above embodiment, the electric signal e is obtained by detecting the rectified voltage using the detection resistor 5, but the present invention is not limited to this, and the output voltage of each piezoelectric transformer is Any type of electrical signal may be used as long as it can obtain an electrical signal that is approximately proportional to the magnitude of the applied voltage.

For example, a configuration may be considered in which a conductor is disposed near the output electrode of one piezoelectric transformer and a voltage induced in the conductor by electrostatic induction is utilized.

Further, in the above embodiment, there is one main piezoelectric transformer and one auxiliary pressure chamber transformer, but there may be a plurality of each, and the configuration of the rectifier circuit is not limited to the embodiment.

As explained above, in the parallel drive method according to the present invention, the main piezoelectric transformer and the auxiliary pressure chamber are connected to each other by appropriately adjusting the phase of the voltage that drives the auxiliary pressure chamber transformer according to the electric signal fed back by the phase control means. This stabilizes the high voltage output voltage obtained by superimposing the output voltages of each transformer to a predetermined value.

Therefore, even if the load that supplies the high voltage output voltage approaches open circuit, the output voltage will always be kept at a constant value, so there will be no risk of the voltage rising and causing discharge or burning of peripheral parts, as in the past. There's nothing to do.

Furthermore, the problem of fluctuations in high voltage output voltage due to temperature fluctuations is also solved.

Furthermore, in the present invention, the value of the high-voltage output voltage is adjusted by changing the phase difference of the drive voltage, and not by changing the magnitude of the drive voltage as in the conventional method. The power loss caused by this is extremely small compared to the case where the magnitude of the drive voltage is changed.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the parallel driving method according to the present invention, and FIG. 2 is a drawing showing the relationship between the superimposed voltage E0 and the phase difference φ, where a is φ=0 and b is U=T. /4, c is the case when φ=T/2. In the figure, 1 is a main piezoelectric transformer, 2 is an auxiliary pressure chamber transformer, 3 is a driving power source, 4 is a rectifier circuit, 5 is a detection resistor, 6 is a phase control means, and 7 is an output terminal.

Claims (1)

[Claims] 1 Consists of a main piezoelectric transformer and a sub-voltage transformer table connected to the drive voltage for driving the main piezoelectric transformer via a phase control means, and obtains a high output voltage by superimposing the output voltages of each piezoelectric transformer. The value of the high-voltage output voltage is stabilized by feeding back an electric signal substantially proportional to the magnitude of the high-voltage output voltage to the phase control means to control the phase of the voltage that drives the sub-voltage transformer. Parallel driving method for piezoelectric transformers.