JP3475687B2 - Power converter - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power converter capable of applying a required voltage and an AC voltage having a substantially continuous waveform to a load by using a power supply unit that generates an AC voltage having a discontinuous waveform. It is a thing.

[0002]

2. Description of the Related Art The inventor of the present invention has heretofore proposed a power converter for converting power from direct current to alternating current by using a switched capacitor and an inverter circuit together. FIG. 17 shows a basic circuit configuration of this type of power conversion device. The switched capacitor, is shown what with three capacitors C ₁ -C _3. Also,
Between the positive electrode and the capacitor C ₁ of the DC power source E and insert the charging switching element S _1, a capacitor C _2, C ₃ and the charge switching element S ₂ ~ respectively between each electrode of the DC power source E S ₅ is inserted. Furthermore, the capacitors C _{1 to} C ₃ and the charging switching elements S ₁ , S ₂ , S.
₄ the discharging switching element S ₈ to S ₁₀ that connects the other end is connected at one end to the common connection point between the provided capacitor C ₁
Of the discharge switching elements S ₆ and S ₇ are inserted between the positive electrode of the capacitor C _{2 and} the negative electrode of the capacitor C ₂ and between the positive electrode of the capacitor C _{2 and} the negative electrode of the capacitor C ₃ , respectively. On-off timing of the charging switching element S ₁ to S ₅ and discharging switching element S ₆ to S ₁₀ is controlled by a control circuit (not shown), discharge switching element S ₈
The potential at the connection point, which is commonly connected to S ₁₀ , is changed stepwise.

On the other hand, the inverter circuit is formed by bridge-connecting switching elements Sa to Sd, and switching elements Sa, Sb and Sc, Sd in each arm in which switching elements Sa to Sd are connected in series.
A series circuit of the load 3 and the inductor L ₁ is connected between the connection points of. A capacitor C ₄ is connected in parallel to the load 3. This type of inverter circuit is well known, and a period for simultaneously turning on the switching elements Sa, Sd or Sb, Sc arranged diagonally of the bridge circuit is provided, and the switching element S of each arm is provided.
a, Sb or Sc, Sd are controlled so as not to be turned on at the same time, and a period in which the switching elements Sa, Sd are simultaneously turned on and a period in which the switching elements Sb, Sc are simultaneously turned on are alternately generated, The polarity of the voltage applied to the load 3 is alternated. Off of the switching element Sa~Sd it is controlled by the same control circuit and the charging switching element S ₁ to S ₅ and discharging switching element S ₆ to S ₁₀ of the switched capacitor.

Therefore, the switched capacitor can generate a voltage that changes stepwise, and the inverter circuit can alternate the polarity of the voltage applied to the load 3. Therefore, the switched capacitor and the inverter circuit are appropriately controlled. As a result, it is possible to apply a sinusoidal AC voltage that changes stepwise (that is, a discontinuous waveform) to the load 3.

By the way, the control circuit includes the switching elements S _{1 to} S ₅ for charging and the switching elements S _{6 to} S for discharging.
_{10. The} switching elements Sa to Sd are controlled at the timing shown in FIG. Now, the operation will be described assuming that the circuit shown in FIG. 17 is performing a steady operation. First,
At time t ₀ , all of the charging switching elements S _{1 to} S ₅ are turned on and the discharging switching element S ₁₀ is turned on. At this time, the voltage across each of the capacitors C _{1 to} C ₃ is charged to a voltage substantially equal to the voltage across the DC power source E, and the voltage V ₁ applied to the inverter circuit is as shown in FIG.
As shown in (o), it becomes substantially equal to the voltage of the DC power source E.

Next, time t₁All charging
Itching element S₁~ S_FiveSwitch off and discharge switch
Element S₆, S₉Only turn on. by this,
Capacitor C₁, C₂Are connected in series and the voltage V₁Is direct current
It becomes almost twice the voltage across the power source E. Furthermore, time t₂To
In this state, the discharge switching element S₉The
Turn off the switching element S₇, S₈If you turn on
All capacitors C ₁~ C₃Connected in series
And voltage V₁Is about 3 times the voltage across DC power supply E
It

Time t₃At time t₁In the same state as
Set, time t_FourAt time t ₀Set to the same state as
To do. Also, at time t_FiveThen time t_FourKeep the state of
One. After that, by repeating the above operation, the voltage V
₁Is a pulsating current in which the voltage rises and falls in a stepwise manner as shown in FIG.
It becomes wavy. On the other hand, the switches that make up the inverter circuit
The ching elements Sa to Sd are shown in FIGS.
As described above, the charging switching element S₁~ S_FiveOh
And discharge switching element S₆~ S_TenPeriod t₀~ T
_FiveFor each series of operation of inductor L₁And capacitor C
_FourThe polarity of the voltage applied to the series circuit of and is inverted. Tsuma
, Period t₀~ T_FiveTurns on the switching elements Sa and Sd.
The switching elements Sb and Sc are turned off.
, Period t_Five~ T_TenTurns on the switching elements Sa and Sd.
The switching elements Sb and Sc are turned on.
It In this way, inductor L₁And capacitor C_Four
The voltage applied to the series circuit of and changes in steps.
And the voltage changes in the form of a sinusoidal AC wave as a whole.
Will be.

As is apparent from the above description, the charging switching elements S ₁ to S _1- .
And S ₅ and discharging switching element S ₆ to S _10, is controlled to the switching element Sa~Sd constituting the inverter circuit interlocked with each other. Further, the period of the voltage applied to the series circuit of the inductor L ₁ and the capacitor C ₄ is easily changed by changing the time interval for switching the on / off combination of the switching elements S _{1 to} S ₁₀ and Sa to Sd. Therefore, with this configuration, it is possible to configure a power supply unit having a variable output frequency.

[0009] In this case, the voltage applied to the series circuit of the inductor L ₁ and capacitor C ₄ are those changes stepwise, the inductor L ₁ and capacitor C ₄
Functions as a filter circuit and can apply an AC voltage V ₂ having a sinusoidal shape that changes substantially continuously as shown in FIG. 18 (p) to the load 3. In this circuit configuration, the switching element S ₁ to S _10, by increasing the frequency for switching Sa to Sd, because it is possible to reduce the energy of a single charging and discharging of each capacitor C ₁ -C _3, a capacitor can reduce the capacitance of C ₁ -C _3, it is possible to provide a compact power converter.

[0010]

By the way, in the above-mentioned configuration, when the load 3 to which a high voltage has to be applied is used, the voltage across the DC power source E is increased or is connected in series for discharging. It is possible to increase the number of capacitors. However, in the former case, the charging switching elements S _{1 to} S ₅ and the discharging switching element S _{6 are}
It requires that a high breakdown voltage as to S _10, a problem that the upsizing occurs become necessary large element size.
Also, in the latter case, the number of parts increases and the size increases, and the number of discharge switching elements connected in series at the time of discharging the capacitor increases, so that the loss due to the resistance of the discharge switching element increases. As a result, the power conversion efficiency decreases.

The present invention has been made in view of the above-mentioned reasons, and it is an object of the present invention to apply a required voltage to a load, not to mention that the voltage applied to the load has a substantially continuous waveform. In this case, it is to provide a power conversion device that does not use a high breakdown voltage element and does not reduce the power conversion efficiency.

[0012]

According to a first aspect of the present invention, there is provided a power source section for outputting alternating current having a discontinuous sinusoidal waveform, a filter element and a power source section for shaping an output voltage waveform of the power source section into a substantially continuous waveform. And a transformer element that converts the output voltage of
A piezoelectric transformer which also serves as the piezoelectric output voltage of the power supply unit
It supplies the load consisting of a discharge lamp through a transformer . According to this configuration, it is possible to shape the voltage waveform into a substantially continuous waveform by using the filter element while using the power source section having a discontinuous output voltage waveform, and transform the voltage using the transformer element. As a result, a desired voltage can be applied to the load without using a high withstand voltage element in the power supply section or reducing the power conversion efficiency. As a result, a relatively small power converter can be provided. Moreover, the piezoelectric transformer does not change with the filter element.
Since it is also used as a pressure element, the number of parts is small and downsizing is possible.
Can be planned. That is, install a piezoelectric transformer
Of the discontinuous sinusoidal waveform output from the power supply.
For shaping the flow into a continuous waveform and for lighting the discharge lamp
It can be transformed into the required high voltage, and with a small number of parts
Can be configured.

[0013] The second aspect of the present invention is, have you to the first aspect of the present invention
The piezoelectric transformer is composed of a drive unit in which a pair of input electrodes are arranged opposite to each other with the piezoelectric element sandwiched between them, and a power generation unit in which an output electrode is provided on the piezoelectric element at a predetermined distance from the drive unit. Is substantially equal to the resonance frequency of the power generation section, and with this configuration, the piezoelectric transformer can be used with high efficiency and high power conversion efficiency can be obtained.

The invention of claim 3 is claim 1 or claim
In the second aspect of the invention, the piezoelectric transformer outputs a voltage capable of stably maintaining the lighting of the discharge lamp. This configuration is the preferred embodiment. According to a fourth aspect of the present invention, in the first to third aspects of the present invention, the power source section includes a plurality of capacitors, a charging switching element inserted in a charging path from the DC power source to the capacitors, and the capacitors to the piezoelectric transformer. And a control circuit for controlling the on / off timing of the charging switching element and the discharging switching element to change the output voltage waveform into a pulsating wave shape stepwise. And a means for inverting the polarity of the output voltage of the switched capacitor for each cycle of the pulsating flow waveform. This configuration is the preferred embodiment. A fifth aspect of the present invention is the power source section according to the first to third aspects of the invention.
However, the positive power supply unit that can obtain the output voltage of positive potential and the negative potential
It consists of a negative power supply unit that obtains the output voltage, and a positive power supply unit and a negative power supply unit.
The power supply unit consists of multiple capacitors and a DC power supply, respectively.
Charging switch inserted in the charging path from the capacitor to the capacitor
And the discharge path from the capacitor to the piezoelectric transformer
And the switching device for charging and the switching device for charging.
ON / OFF of the switching element and the switching element for discharge
The output voltage waveform can be changed stepwise by controlling the timing.
Switch consisting of a control circuit with a pulsating wave shape that changes
The control circuit consists of a positive capacitor and a negative power source.
AC voltage of the output voltage by alternately operating
It is a state. This configuration is the preferred embodiment.
It

According to the invention of claim 6, in the invention of claims 1 to 5, the output voltage of the power source is made variable, and is particularly effective when a load with a low applied voltage is used. According to a seventh aspect of the invention, the piezoelectric element is provided with an output electrode at a predetermined distance from a power source section that outputs an alternating current having a discontinuous sinusoidal waveform and a drive section that is provided with a pair of input electrodes facing each other with the piezoelectric element sandwiched therebetween. It is a transformer with a power generation part formed and the output voltage waveform of the power supply part is made into a substantially continuous waveform.
A piezoelectric transformer that shapes and converts the output voltage of the power supply unit is provided, and the power supply unit includes a plurality of capacitors,
The charging switching element inserted in the charging path from the DC power supply to the capacitor, the discharging switching element inserted in the discharging path from the capacitor to the piezoelectric transformer, the on / off timing of the charging switching element and the discharging switching element A switch capacitor, which comprises a control circuit having a pulsating current waveform in which the output voltage waveform is changed stepwise by controlling, is provided, and a means for inverting the polarity of the output voltage of the switched capacitor for each cycle of the pulsating waveform is provided. The output frequency of the power supply unit is set to substantially match the resonance frequency of the power generation unit of the piezoelectric transformer, and the output voltage of the power supply unit is applied to the discharge lamp via the piezoelectric transformer. According to this configuration, even if the output voltage waveform as the power supply unit while using those changes stepwise can shape the piezoelectric transformer substantially continuous waveform voltage waveform using as a filter element, yet the piezoelectric transformer transformer Since it functions as an element, it is possible to apply a desired voltage to the load without using a high breakdown voltage element in the power supply section or reducing the power conversion efficiency.
As a result, a relatively small power converter can be provided. Moreover, it is possible to from the piezoelectric transformer is also used as a transformer element and the filter element, miniaturization without small number of parts. Furthermore, since the output frequency of the power supply unit is made to substantially match the resonance frequency of the power generation unit of the piezoelectric transformer, the piezoelectric transformer can be used with high efficiency and high power conversion efficiency can be obtained.

[0016]

DETAILED DESCRIPTION OF THE INVENTION

(Embodiment 1) In the present embodiment, as shown in FIG. 1, a first power supply unit 2a that outputs a pulsating wave-shaped voltage that changes stepwise, and four switching elements Sa that are bridge-connected. The power supply unit is configured by the second power supply unit 2b including the inverter circuit including Sd. The primary winding of the leakage transformer T ₁ as a transformer element is connected between the connection points of a pair of series-connected switching elements Sa, Sb and Sc, Sd forming each arm of the bridge. The load 3 is connected to the secondary winding of the leakage transformer T ₁ . Capacitor C ₄ is connected in parallel to the leakage primary winding of the transformer T _1, also configured filter element by the leakage component and the capacitor C ₄ of the leakage transformer T _1. This filter element is set to pass only the fundamental wave component of the power supply section. Therefore, the output voltage waveform of the second power supply section 2b is stepwise and discontinuous, but a substantially continuous voltage waveform is obtained in the secondary winding of the leakage transformer T ₁ . Further, since the leakage transformer T ₁ is used, the transformation ratio can be set appropriately, and a required voltage that is stepped up or stepped down can be applied to the load 3.

When the high voltage is applied to the load 3 when the voltage is boosted by the leakage transformer T ₁ , the _first voltage is applied.
It is possible to provide a small power change circuit without requiring a high breakdown voltage element in the power supply unit 2a or the second power supply unit 2b and without increasing the number of parts. Moreover, since the voltage waveform applied to the load 3 is made substantially continuous in a sine wave shape, power can be stably supplied to the load 3 and noise is reduced.

(Embodiment 2) In this embodiment, as shown in FIG. 2, the switched capacitor shown in FIG. 17 is used as the first power supply section 2a, and the stepped shape shown in FIG. Is configured to be output from the second power supply unit 2b. In this configuration, the leakage transformer T
_A sinusoidal AC voltage is obtained at the secondary winding of No.2. Other configurations and operations are similar to those of the first embodiment.

(Third Embodiment) This embodiment is the second embodiment.
Capacitor C in_FourI changed the position of
Then, as shown in FIG. 3, the leakage transformer T₁Primary of
Capacitor C in the winding_FourAre connected in series. Other configurations
And the operation is the same as that of the second embodiment. (Embodiment 4) This embodiment is carried out as shown in FIG.
Leakage transformer T in form 2 ₁Instead of piezoelectric
Lance T₂Is used, and the load 3 is a capacitor
C_FiveAre connected in parallel. Therefore, the first power supply unit 2a
The configuration of the second power supply unit 2b is similar to that of the second embodiment.
Is.

The piezoelectric transformer T ₂ has a pair of input electrodes 12a, 12 at one end portion of the rectangular parallelepiped piezoelectric element 11 in the longitudinal direction.
b facing each other, and the output electrode 13 is provided on the other end face in the longitudinal direction.
Has a shape provided with. Both input electrodes 12a, 12b
During this period, the power generation unit 16 functions as the drive unit 15, and the power generation unit 16 is formed between the drive unit 15 and the output electrode 13. The piezoelectric transformer T ₂ is configured such that a mechanical vibration is generated in the piezoelectric element 11 by applying an AC voltage to the drive unit 15, and the voltage generated by this mechanical vibration is taken out from the output electrode 13. Since mechanical vibration has inertia, it equivalently functions as a filter circuit. Further, the piezoelectric transformer T ₂ has a resonance frequency corresponding to the length dimension of the power generation section 16, and a voltage having a frequency close to this resonance frequency is applied to the input electrodes 12a and 12b to cause the piezoelectric element 11 to resonate. As a result, it is possible to obtain a greatly boosted voltage from the output electrode 13.

As described above, since the piezoelectric transformer T ₂ has both a function as a filter element and a function as a boosting element, it is not necessary to separately provide an element for forming the filter element. Moreover, the piezoelectric transformer T ₂ can be downsized as compared with a transformer in which a winding is provided on an iron core, which leads to downsizing or a low profile (thinning) as a whole.

Each switching element S in this embodiment
_{1 to} S ₁₀ and Sa to Sd are controlled by a control circuit (not shown).
It is controlled at the timing like. This timing is the same as the timing in the conventional configuration shown in FIG. That is, as shown in FIG. 5 (o), the output voltage V ₁ of the first power supply unit 2a is the same as that of the conventional example, and as shown in FIG. 5 (p), the output voltage of the second power supply unit 2b is also the same as that of the conventional example. It becomes a sine wave AC wave shape which is a step shape of. Here, the piezoelectric transformer T
By applying a voltage to the load 3 via ₂ ,
As shown in (q), it is possible to apply a sinusoidal AC waveform and a boosted voltage to the load 3. Other configurations and operations are similar to those of the conventional example.

(Embodiment 5) In this embodiment, as shown in FIG. 6, the capacitor C ₅ connected in parallel with the load 3 in Embodiment 4 is omitted. Second in this configuration
The output frequency of the power supply unit 2b, by substantially coincides with the resonance frequency of the power generation portion 16 of the piezoelectric transformer T _2, without the capacitor C ₅ and applying an AC voltage of a continuous wave to the load 3, the power with low noise We are able to supply it. Other configurations and operations are similar to those of the fourth embodiment.

(Embodiment 6) In this embodiment, as shown in FIG. 7, the load 3 in the configuration of Embodiment 4 is replaced by a cold cathode 32.
The discharge lamp 31 is provided with. With this configuration,
A high voltage is required at the time of starting the discharge lamp 31, but the output voltage of the first power supply unit 2a and the second power supply unit 2b may be low, so that the elements forming the first power supply unit 2a and the second power supply unit 2b. It is not necessary to use a high withstand voltage, and a high voltage can be obtained while using a low withstand voltage element. Other configurations and operations are similar to those of the fourth embodiment.

(Embodiment 7) In this embodiment, as shown in FIG. 8, the load 3 in the configuration of Embodiment 4 is a discharge lamp 31 having a hot cathode (filament) 33. A capacitor C ₆ is connected between the ends of both filaments 33. Therefore, at the time of preheating, by passing an electric current through the capacitor C ₅ , the filament 3
3 can be heated, and thereafter, by applying a high voltage boosted by the piezoelectric transformer T ₂ to the discharge lamp 31,
The discharge lamp 31 can be started. Other configurations and operations are similar to those of the fourth embodiment.

(Embodiment 8) In this embodiment, as shown in FIG. 9, in the structure of Embodiment 4 shown in FIG. 6, a capacitor C ₄ is connected in parallel to the primary side of the piezoelectric transformer T ₂ .
A series circuit of a capacitor C ₄ and an inductor L ₁ is connected between the output terminals of the second power source section 2b. Generally, since the piezoelectric transformer T ₂ has a capacitive component, an inrush current may flow when the output voltage of the second power supply section 2b is applied. However, in the circuit configuration of this embodiment, the piezoelectric transformer T ₂ and By connecting the inductor L ₁ in series to the parallel circuit of the capacitor C _4, a choke input type circuit is formed, and the inrush current can be reduced. Therefore, it is possible to suppress the generation of stress and noise due to the inrush current. Other configurations and operations are similar to those of the fourth embodiment.

(Embodiment 9) This embodiment is shown in FIG.
As described above, in the configuration of the fifth embodiment shown in FIG.
An inductor L is provided between the first power supply unit 2a and the second power supply unit 2b.₂
And capacitor C ₇A filter circuit consisting of
Of. This filter circuit is a choke input type
It is a low-pass filter that is output from the first power supply unit 2a.
A function to smooth a stepped discontinuous voltage waveform
There is also a piezoelectric transformer T₂Reduce the inrush current to
Have a function that Therefore, as in the eighth embodiment,
It is possible to suppress the generation of stress and noise due to electric current.
Wear. Other configurations and operations are similar to those of the fourth embodiment.

(Embodiment 10) As shown in FIG. 11, the present embodiment realizes a power supply unit which can obtain an output voltage having a stepwise and sine wave AC waveform by using only a switched capacitor without using an inverter circuit. To do. That is, the positive power supply unit 2 including a switched capacitor having the same configuration as the switched capacitor shown in the conventional example.
c and the negative power supply unit 2d are provided. However, the positive power supply section 2c and the negative power supply section 2d are connected to the DC power supply E in opposite polarities. Therefore, as described in the conventional example, the positive power supply unit 2c obtains an output voltage having a stepwise and pulsating wave shape at a positive potential, and the negative power supply unit 2d has a stepwise and pulsating current wave with the polarity reversed. A shaped output voltage is obtained. That is, by alternately operating the positive power supply unit 2c and the negative power supply unit 2d, it is possible to obtain a stepwise and sinusoidal AC wave-shaped output.

A more specific description will be given. Positive power supply portion 2c is a switched capacitor of the same configuration described in the conventional example, the capacitor C ₁ -C _3, charge switching element S
_{1 to} S ₅ and discharge switching elements S _{6 to} S ₁₀ . On the other hand, the negative power supply unit 2d, the capacitors C ₁₁ -C
₁₃ , the switching elements S _{11 to} S ₁₅ for charging and the switching elements S _{16 to} S ₂₀ for discharging. Positive power supply 2c
And the negative power supply 2d have the same configuration, but the positive power supply 2
The difference is that the capacitor C ₁ is connected to the negative electrode of the DC power supply E in c, whereas the capacitor C ₁₁ is connected to the positive electrode of the DC power supply E in the negative power supply unit 2d. Further, one ends of the discharging switching elements S _{18 to} S ₂₀ are commonly connected to the output terminals to which one ends of the discharging switching elements S _{8 to} S ₁₀ are commonly connected. A piezoelectric transformer T ₂ is inserted between the power source section and the load 3, and discharge switching elements S _{8 to} S
_10, one end of the S ₁₈ to S ₂₀ are connected in common to one input terminal 12a of the piezoelectric transformer T _2, and the other input terminal 12b is connected to the negative electrode of the DC power source E.

Therefore, each switching element S _{1 to} S ₂₀
Is controlled by a control circuit (not shown) as shown in FIGS. That is, during the period t _{0 to} t ₁ , the charging switching elements S _{1 to} S ₅ and the discharging switching element S ₁₀ are turned on, and a voltage substantially equal to the voltage across the DC power source E as shown in FIG. Is output. Next, at time t ₁ , the charging switching elements S _{1 to} S ₅ and the discharging switching element S ₁₀ are turned off, and the discharging switching elements S ₆ and S ₉ are turned on.
As a result, the capacitors C ₁ and C ₂ are connected in series,
The voltage V ₁ is almost twice the voltage across the DC power source E. In yet time t _2, the turn off the discharge switching element S ₉ from this state, when turning on the switching element S _7, S _8, it will be connected to all of the capacitors C ₁ -C ₃ in series, the voltage V ₁ becomes almost three times the voltage across the DC power source E.

Time t₃At time t₁In the same state as
Set, time t_FourAt time t ₀Set to the same state as
To do. Also, at time t_FiveThen time t_FourKeep the state of
One. During the series of operations described above, the switching element S₁₁
~ S₂₀Are all kept off. This kind of operation
Piezoelectric transformer T₂Applied to the input terminals 12a and 12b of
Voltage V₁Is positive and stepped as shown in FIG.
Up and down.

Time t_FiveThen, the above operation is performed by the negative power supply unit.
2d, the period t_Five~ T₆Then
Switching element S for charging₁₁~ S₁₅And discharge switch
Holding element S₂₀Is turned on, and as shown in Fig. 12 (u),
A negative voltage substantially equal to the voltage across the current source E is output.
Next, time t₆At the switching element S for charging ₁₁
~ S₁₅And discharge switching element S₂₀Off,
Switching element S for discharge₁₆, S₁₉Turn on. this
By the capacitor C₁₁, C₁₂Are connected in series and the voltage
V₁Is approximately twice the voltage across the DC power source E. further
Time t₇In this state, the switching element for discharge is
Child S₁₉To turn off the switching element S ₁₇, S₁₈Turn on
Then all capacitors C₁~ C₃Connected in series
That is, the voltage V₁Is the voltage across the DC power source E
I will triple it.

Time t₈At time t₆In the same state as
Set, time t₉At time t ₀Set to the same state as
To do. Also, at time t_TenThen time t₉Keep the state of
One. During the series of operations described above, the switching element S₁
~ S_TenAre all kept off. This kind of operation
Piezoelectric transformer T₂Applied to the input terminals 12a and 12b of
Voltage V₁Is the period t_Five~ T_TenIn Fig. 12
Like (u), it has a negative polarity and rises and falls in a stepwise manner.

By repeating the above operation, it is possible to obtain an output voltage that changes in a stepwise and sinusoidal AC waveform, and by passing the piezoelectric transformer 1, the output voltage shown in FIG.
It becomes possible to apply a sinusoidal high voltage as shown in (v) to the load 3. Even with this configuration, it is possible to provide a low-noise power changing device. (Embodiment 11) In this embodiment, as shown in FIG.
In the configuration of the fourth embodiment, the output voltage of the DC power source E is variable. According to this configuration, the voltage applied to the load 3 and the piezoelectric transformer T ₂ can be changed by adjusting the voltage across the DC power source E. In particular, it is effective when the applied voltage to the load 3 is to be reduced.

Load 3 and piezoelectric transformer T₂Applied voltage to
To reduce it, change the output voltage of the DC power supply E.
Not the switching element S₁~ S_TenControl the first power
The peak value of the output voltage of the source 2a is the voltage across the DC power source E.
It is also possible to suppress it to twice. Other configurations and
The operation is similar to that of the fourth embodiment. (Embodiment 12) In this embodiment, as shown in FIG.
There is a switch between the DC power supply E and the switched capacitor.
Insert a series circuit of the switching element Sx and impedance element Z
In addition, the switching element Sx and the DC power source E are connected directly to each other.
Diode D in the column circuit₁Have a configuration in which they are connected in parallel.
In this configuration, the charging switching element S₁~ S₃Noi
The switching element Sx is turned on during the period when the shift is on.
And the capacitor C through the impedance element Z.₁~
C₃By charging the capacitor C₁~ C ₃of
The voltage at both ends is made low. Therefore,
By appropriately controlling the switching element Sx, the first
It becomes possible to adjust the output voltage of the power supply unit 2a. Na
Oh, diode D₁Is for regeneration. Impeda
As the element Z, as shown in FIGS.
Resistance R₀, Inductor L₀, Inductor L₀And Conde
Sensor C₀It is possible to use various things such as a series circuit with
Wear. Other configurations and operations are similar to those of the fourth embodiment.

(Embodiment 13) In the present embodiment, as shown in FIG. 16, in the configuration of Embodiment 4, the first power supply unit 2 is used.
The impedance element Z ₂ is inserted between a and the second power supply unit 2b, the capacitor C ₇ is connected between the input ends of the second power supply unit 2b, and the regenerative operation is performed between the output ends of the first power supply unit 2a. The diode D ₂ for use is connected.

According to this configuration, the capacitor C₁~ C₃
Impedance element Z in the discharge path of ₂Has been inserted
From the switching element S₈~ S_TenThe on period of
If so, the input voltage to the second power supply section 2b can be adjusted.
And become possible. Where impedance element Z₂In
The same thing as the twelfth embodiment can be used. other
The configuration and operation are similar to those of the fourth embodiment.

[0038]

According to the first aspect of the present invention, there are provided a power supply section for outputting alternating current having a discontinuous sinusoidal waveform, a filter element for shaping the output voltage waveform of the power supply section into a substantially continuous waveform, and an output voltage of the power supply section. Piezoelectric tiger that doubles as a voltage conversion element
A Nsu, the output voltage of the power supply unit is intended to supply the load consisting of the discharge lamp Te <br/> through a piezoelectric transformer, the filter element while using those output voltage waveform is discontinuous as a power supply unit Can be used to shape the voltage waveform into a nearly continuous waveform, and by using a transforming element to transform, a high withstand voltage element can be used in the power supply section or power conversion efficiency can be reduced. It is possible to apply a desired voltage to the load without the need. as a result,
There is an advantage that a relatively small power converter can be provided. Moreover, the piezoelectric transformer and the filter element
Since it is also used as a transformer element, it has a small number of parts and is compact.
Can be achieved. That is, a piezoelectric transformer is provided.
Of the discontinuous sinusoidal waveform output from the power supply
Shapes alternating current into a continuous waveform and turns on the discharge lamp
It is possible to transform to the high voltage required for, and the number of parts is small.
It has the advantage that it can be configured with.

[0039] As the invention of claim 2, pressure electric transformer, and a driving unit disposed facing a pair of input electrodes sandwiching the piezoelectric element, provided with an output electrode on the piezoelectric element away from the drive unit by a predetermined distance In the case where the output frequency of the power supply unit is made to substantially match the natural frequency of the power generation unit, the piezoelectric transformer can be used with high efficiency and high power conversion efficiency can be obtained.

According to the sixth aspect of the present invention, in the case where the output voltage of the power supply unit is variable, when the load with the low applied voltage is used, it is only necessary to lower the output voltage of the power supply unit. Therefore, the applied voltage is low. It has the advantage that it can handle loads. According to a seventh aspect of the invention, the piezoelectric element is provided with an output electrode at a predetermined distance from a power source section that outputs an alternating current having a discontinuous sinusoidal waveform and a drive section that is provided with a pair of input electrodes facing each other with the piezoelectric element sandwiched therebetween. And a piezoelectric transformer configured to shape the output voltage waveform of the power supply unit into a substantially continuous waveform and to convert the output voltage of the power supply unit into a voltage. A plurality of capacitors, a charging switching element inserted in the charging path from the DC power supply to the capacitor, a discharging switching element inserted in the discharging path from the capacitor to the piezoelectric transformer, a charging switching element and a discharging switching A switched capacitor composed of a control circuit that forms a pulsating current waveform in which the output voltage waveform changes stepwise by controlling the on / off timing of the element. With obtaining comprises means for inverting the polarity of the output voltage of the switched capacitor in each cycle of the pulsating voltage, the output frequency of the power supply unit is set so as to substantially coincide with the natural frequency of the power generating portion of the piezoelectric transformer,
The output voltage of the power supply is applied to the discharge lamp via a piezoelectric transformer.Although the output voltage waveform changes stepwise as the power supply, the piezoelectric transformer is used as a filter element to make the voltage waveform almost continuous. can be shaped into waveform, moreover since the piezoelectric transformer serves as a transformer element, or using a high breakdown voltage of the device to the power supply unit, without or reduce the power conversion efficiency, it is applied to the load a desired voltage Has the advantage that it is possible. As a result, there is an effect that a relatively small power converter can be provided. Moreover, since the piezoelectric transformer is also used as a transformer element and the filter element, the small without the small parts
It has the effect that it can be made into a mold , and since the output frequency of the power supply unit is made to substantially match the natural frequency of the power generation unit of the piezoelectric transformer, the piezoelectric transformer can be used with high efficiency and high power conversion efficiency can be achieved. It has the advantage that it can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic circuit diagram showing a first embodiment.

FIG. 2 is a circuit diagram showing a second embodiment.

FIG. 3 is a main part circuit diagram showing a third embodiment.

FIG. 4 is a circuit diagram showing a fourth embodiment.

FIG. 5 is an operation explanatory diagram of the above.

FIG. 6 is a main part circuit diagram showing a fifth embodiment.

FIG. 7 is a main part circuit diagram showing a sixth embodiment.

FIG. 8 is a main part circuit diagram showing a seventh embodiment.

FIG. 9 is a circuit diagram showing an eighth embodiment.

FIG. 10 is a circuit diagram showing a ninth embodiment.

FIG. 11 is a circuit diagram showing a tenth embodiment.

FIG. 12 is an explanatory diagram of an operation of the above.

FIG. 13 is a main part circuit diagram showing an eleventh embodiment.

FIG. 14 is a main part circuit diagram showing a twelfth embodiment.

FIG. 15 is a diagram showing an example of impedance elements used in the above.

FIG. 16 is a main part circuit diagram showing a thirteenth embodiment.

FIG. 17 is a circuit diagram showing a conventional example.

FIG. 18 is an operation explanatory diagram of the above.

[Explanation of symbols]

2a first power supply portion 2b second power supply unit 3 load 11 piezoelectric elements 12a, 12b input electrodes 13a, 13b output electrode 15 driver 16 the power generation unit 31 discharge lamp 33 filaments _{C 1 ~C 3, C 11 ~C} 13 capacitor C ₄ Capacitor L ₁ Inductor S _{1 to} S ₅ , S _{11 to} S ₁₅ Charging switching element S _{6 to} S ₁₀ , S _{16 to} S ₂₀ Discharging switching element T ₁ Leakage transformer T ₂ Piezoelectric transformer

Claims (7)

(57) [Claims] 1. A power supply section for outputting alternating current of a discontinuous sinusoidal waveform, and an output voltage waveform of the power supply section into a substantially continuous waveform.
A piezoelectric transformer that also functions as a shaping filter element and a transformer element that converts the output voltage of the power supply unit into a voltage, and supplies the output voltage of the power supply unit to a load consisting of a discharge lamp through the piezoelectric transformer. Power converter. 2. The piezoelectric transformer sandwiching a piezoelectric element.
A drive unit in which a pair of input electrodes are arranged opposite to each other, and
With a power generation unit with an output electrode on the piezoelectric element separated by a fixed distance
And the output frequency of the power supply unit to the resonance frequency of the power generation unit.
The power conversion device according to claim 1 , wherein the power conversion devices are substantially matched with each other . 3. The piezoelectric transformer stabilizes the discharge lamp.
It is characterized by outputting a voltage that can maintain lighting.
The power conversion device according to claim 1 or 2 . 4. The power supply unit includes a plurality of capacitors,
Charging inserted in the charging path from the DC power supply to the capacitor
Switching elements and capacitors to piezoelectric transformers
Discharge switching element inserted in the discharge path of
Power switching elements and discharge switching elements
The output voltage wave can be controlled by controlling the on / off timing.
From a control circuit with a pulsating wave shape whose shape changes stepwise
Equipped with a switched capacitor
Reverse the polarity of the output voltage of the
Claim 1 thru | or Claim which is provided with the means to operate.
The power conversion device according to any one of 3 above. 5. The power source is capable of obtaining a positive potential output voltage.
Positive power supply part and negative power supply part that can obtain negative potential output voltage
And the positive power supply unit and the negative power supply unit each have a plurality of
In the capacitor and the charging path from the DC power supply to the capacitor
From the inserted charging switching element and capacitor
Discharge switch inserted in the discharge path to the piezoelectric transformer
Switching element, charging switching element and discharging switch.
To control the on / off timing of the switching element
The output voltage waveform has a pulsating wave shape that changes gradually.
It consists of a switched capacitor consisting of a control circuit and
The control circuit should operate the positive power supply and the negative power supply alternately.
The output voltage has an AC waveform by
The power conversion device according to any one of claims 1 to 3 . 6. The power conversion device according to claim 1, wherein the output voltage of the power supply unit is variable. 7. A power supply unit for outputting alternating current having a discontinuous sinusoidal waveform and a drive unit in which a pair of input electrodes are opposed to each other with a piezoelectric element interposed therebetween, are separated from each other by a predetermined distance, and an output electrode is provided on the piezoelectric element to generate electricity. And a piezoelectric transformer that shapes the output voltage waveform of the power supply unit into a substantially continuous waveform and that converts the output voltage of the power supply unit into a voltage,
The power supply unit includes a plurality of capacitors, a charging switching element inserted in a charging path from the DC power supply to the capacitor, a discharging switching element inserted in a discharging path from the capacitor to the piezoelectric transformer, and a charging switching element. And a switching capacitor comprising a control circuit having a pulsating wave shape in which the output voltage waveform is changed stepwise by controlling the on / off timing of the discharge switching element, and the polarity of the output voltage of the switched capacitor is pulsated. A means for inverting the waveform every cycle is provided, and the output frequency of the power supply unit is set to substantially match the resonance frequency of the power generation unit of the piezoelectric transformer, and the output voltage of the power supply unit is applied to the discharge lamp via the piezoelectric transformer. A power conversion device characterized by: