JP6420798B2 - Switchable high-voltage power supply circuit - Google Patents

Description

  The present invention relates to a switching type high-voltage power supply circuit that alternately outputs two-output rectangular waves.

  As a high-voltage power supply circuit, a circuit that converts an input voltage into a rectangular wave voltage using a piezoelectric transformer and outputs the voltage to a load is known. In this type of high voltage, a voltage corresponding to the value of the flat portion is applied to the load during the time of the flat portion of the rectangular wave. Therefore, by controlling the duty of the rectangular wave, The power supply can be controlled.

  In this type of high-voltage power supply circuit, as shown in Patent Document 1 and Patent Document 2, the input voltage is turned on / off by a switching circuit having a constant frequency to control the duty of the rectangular wave. In this case, it is difficult to increase the response speed of the rectangular wave, that is, the rising / falling speed of the rectangular wave in a load with a large load current or load capacity. In particular, since the output charge / discharge time depends on the load, it is difficult to increase the response speed (rise / fall time).

  In order to solve such problems, the present applicant has proposed a high-voltage power supply circuit of Japanese Patent Application No. 2015-888888 as shown in Patent Document 3. This high-voltage power supply circuit uses a plurality of Zener diodes connected in series to improve response speed, and takes out an output voltage from the middle stage thereof. In this high-voltage power supply circuit, even if the output voltage value is set to, for example, twice the load voltage value, the rise time is halved and the switching circuit is turned on / off at a low frequency, the output voltage is rectangular. It can be made into waves.

JP 2009-163951 A JP 2012-155857 A Japanese Patent Application No. 2015-201044

  By the way, in this type of high-voltage power supply circuit, there is a demand for a technique for outputting two outputs alternately at different timings. For example, this is a case where two loads are alternately driven by alternately supplying voltages to the two loads.

  In the case of using the circuit of Patent Document 3 for such an application, in the prior art, two power supply circuits having a piezoelectric transformer are prepared, and the outputs of both are switched by a relay provided at the front stage of each load.

  That is, since the circuit of Patent Document 3 takes out the output voltage from the middle part of the plurality of Zener diodes provided at the subsequent stage of the piezoelectric transformer, the output off time when the output voltage becomes zero by the on / off signal for controlling the relay Occurs. Therefore, when one piezoelectric transformer is used and two circuits are provided at the subsequent stage, voltage cannot be supplied from one system to the other system during this output off time. Therefore, unavoidably, by providing two piezoelectric transformers and driving them independently, even if there is an output off time in each system, two outputs with different timings are alternately obtained as a whole circuit.

  However, the preparation of two piezoelectric transformers has the disadvantages that the number of parts increases, the circuit configuration becomes complicated, and two relatively expensive members called piezoelectric transformers are required.

  An object of the present invention is to provide a high-voltage power supply circuit that alternately outputs two systems of rectangular wave voltages at different timings with a simple circuit configuration using one piezoelectric transformer.

The high-voltage power supply circuit of the present invention is characterized by having the following configuration.
(1) An input power supply that outputs a constant voltage.
(2) A transformer that converts a voltage from the input power source into a predetermined pulse wave and outputs a voltage value higher than a load voltage value.
(3) A driving circuit for the transformer.
(4) First and second waveform shaping circuits which are connected in parallel to the secondary side of the transformer and output a rectangular wave by cutting the output voltage value of the transformer into a load voltage value.
(5) In the above first and second waveform shaping circuit, a resistor arranged in series before Quito lance side of the take-out portion of the output voltage, the zener diode provided in series with the ground side of the take-out portion.
(6) First and second loads connected to the secondary side of the transformer via the first and second waveform shaping circuits.
(7) First and second falling processing relays provided between the secondary side of the transformer and the first and second loads.
(8) A relay control circuit that outputs an off signal to the first and second falling processing relays when the rectangular wave falls.
(9) A signal processing circuit that is provided in the relay control circuit and inverts or phase shifts an off signal supplied to one of the first and second falling processing relays.

The switched high-voltage power supply circuit of the present invention preferably has the following configuration.
(1) The transformer is a piezoelectric transformer.
(2) The output voltage value of the piezoelectric transformer is at least twice the load voltage value.

  In the present invention, the waveform shaping circuit has a configuration in which a Zener diode and a resistor are connected in series, and the output is taken out from the intermediate portion thereof, so that the voltage is maintained by the resistance of the waveform shaping circuit and the output from the piezoelectric transformer is maintained. Can do. As a result, it is possible to switch the supply of the rectangular wave voltage from the first load to the second load while the voltage is maintained by the resistance of the waveform shaping circuit, and two outputs are alternately switched by one piezoelectric transformer. Can be switched.

The circuit which shows 1st Embodiment of the switching type | mold high voltage power supply circuit of this invention. In the prior art, the output voltage waveform diagram when a resistive load is connected. In the prior art, the output voltage waveform diagram when a capacitive load is connected. FIG. 6 is a waveform diagram of an output voltage when a capacitive load is connected to a switching type high voltage power supply circuit that uses a relay or the like to increase the falling speed. The wave form diagram of the output voltage at the time of connecting a capacitive load to 1st Embodiment. The circuit which shows 2nd Embodiment of the switching type high voltage power supply circuit of this invention.

Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.
[1. First Embodiment]
[1-1. Constitution]
The switched high-voltage power supply circuit of the present embodiment is connected to an input power supply 1 that outputs a constant voltage, a piezoelectric transformer 2 that converts a voltage from the input power supply 1 into a load voltage value, and a secondary side of the piezoelectric transformer 2. The first and second loads 31 and 32 are provided. The first and second loads 31 and 32 are capacitive loads having a predetermined resistance value and a capacitance value and a large capacitance value. The piezoelectric transformer 2 is controlled by a drive circuit, which will be described later, and outputs a pulse wave having a predetermined peak value and period from a constant voltage value from the input power supply 1, and the peak of the pulse wave is greater than the load voltage value. Output a voltage that is twice as high as the load voltage value in this embodiment.

  In the present embodiment, since the output voltage for the loads 31 and 32 is determined by the Zener diode TD and the resistor R of the first and second waveform shaping circuits 71 and 72 that clamp the output voltage from the piezoelectric transformer 2, for example, it is doubled. In this case, the voltage value between the rectifier circuit 6 and the resistor R is set to the same voltage value as that between the output portions of the waveform shaping circuits 71 and 72 and GND, thereby obtaining a double output voltage. As a method for controlling the output voltage from the piezoelectric transformer 2, phase angle control, frequency control, power supply line dropper control, or the like is used. If the boost ratio is insufficient, the LC resonance L can be compensated for by an autotransformer or the like.

  A switching circuit 4 to which a constant voltage from the input power supply 1 is supplied is connected to the primary side of the piezoelectric transformer 2. The switching circuit 4 is connected to an oscillation circuit 5 that controls the on / off interval. The switching circuit 4 and the oscillation circuit 5 constitute a drive circuit for the piezoelectric transformer 2.

  A rectifier circuit 6 is connected to the secondary side of the piezoelectric transformer 2, and a waveform shaping circuit 71 that cuts the upper part of the output voltage value of the piezoelectric transformer 2 to a voltage value required by the loads 31 and 32 on the output side of the rectifier circuit 6. , 72 are connected. In this embodiment, the waveform shaping circuits 71 and 72 are formed by connecting a plurality of resistors R and a plurality of Zener diodes TD in series, and the end of the resistor R side of the piezoelectric transformer 2 that has passed through the rectifier circuit 6. An output voltage is applied. Output voltages for the loads 31 and 32 are extracted from the middle stage of the plurality of resistors R and Zener diodes TD connected thereto.

  In the present embodiment, the output voltage value of the piezoelectric transformer 2 is set to be twice the load voltage value, and the waveform shaping circuits 71 and 72 make the output voltage value of the piezoelectric transformer 2 higher than the load voltage value. The high part is cut. Therefore, the waveform of the voltage value output from the waveform shaping circuits 71 and 72 to the loads 31 and 32 is a rectangular wave having a flat portion whose maximum voltage value is equal to the load voltage value. The anode sides of the waveform shaping circuits 71 and 72 are grounded together with the ground side ends of the loads 31 and 32.

  An output value detection circuit 8 that detects the output voltage value of the piezoelectric transformer 2 and outputs it to the oscillation circuit 5 is connected to the output side of the rectifier circuit 6. The output side of the output value detection circuit 8 is connected to the oscillation circuit 5. A constant voltage from the input power supply 1 is input to the oscillation circuit 5 and a waveform of the output voltage of the piezoelectric transformer 2 from the output value detection circuit 8 is input. A drive signal having a frequency of 2 output voltages is output. In response to the input of the drive signal, the piezoelectric transformer 2 boosts the voltage (drive voltage) of the drive signal at a boost ratio determined by the drive frequency, and outputs an output voltage from the secondary side.

  In the present embodiment, that is, between the first waveform shaping circuit 71 and the first load 31, a first falling processing relay 91 is connected to the first load 31 on the secondary side of the piezoelectric transformer 2. Connected in parallel. A second fall processing relay 92 is connected in parallel with the second load 32 between the second waveform shaping circuit 72 and the second load 32.

  A relay control circuit 10 is connected to the relays 91 and 92, and the relays 91 and 92 are actuated by an off signal from the relay control circuit 10 to cut off an output current from the piezoelectric transformer 2 to the loads 31 and 32. That is, since the breaking speed of the relays 91 and 92 is much faster than that of the capacitive loads 31 and 32, the output voltage value of the piezoelectric transformer 2 applied to the loads 31 and 32 is rapidly cut off and the falling speed is reduced. Is output to the loads 31 and 32.

  Between the relay control circuit 10 and the second relay 92, a signal processing circuit 11 that inverts or phase-shifts an on / off signal output from the relay control circuit 10 is provided. When the ON signal is supplied to the first relay 91, the signal processing circuit 11 outputs the ON / OFF signal output from the control circuit 10 to the second relay 92. When the OFF signal is supplied to the first relay 91, the signal is inverted or phase-shifted so that the ON signal is supplied to the second relay 92.

[1-2. Action]
(1) Generation of rectangular wave voltage In this embodiment, since the output voltage value of the piezoelectric transformer 2 is higher than the load voltage value, the waveform shaping circuits 71 and 72 have a peak value as shown by the dotted line in FIG. A high pulse wave is input. Since the output voltage of the piezoelectric transformer 2 is higher than the load voltage value, this waveform value is compared with the case where the output voltage value from the piezoelectric transformer 2 is equal to the load voltage value as shown in FIGS. The rise of the waveform is short.

  Such a pulse wave with a high peak value output from the piezoelectric transformer 2 is input to the waveform shaping circuits 71 and 72. The waveform shaping circuits 71 and 72 cut a voltage value higher than a predetermined load voltage value in the output voltage waveform of the piezoelectric transformer 2 according to the constant voltage output characteristic of the Zener diode TD. Therefore, in the output voltage waveforms output from the waveform shaping circuits 71 and 72, a flat portion equal to the load voltage value is necessarily formed, and a rectangular wave having the load voltage value continuing for a predetermined time is applied to the loads 31 and 32. Can be output.

  When the rectangular waves output from the waveform shaping circuits 71 and 72 to the loads 31 and 32 reach the falling point, the relays 91 and 92 are turned off by the off signal from the relay control circuit 10, and the waveform shaping circuit 71 is turned off. , 72 are short-circuited, the output voltage from the piezoelectric transformer 2 to the loads 31, 32 is cut off. Therefore, the falling of the rectangular wave is performed quickly without being affected by the capacity of the loads 31 and 32.

  In the present embodiment, an output value detection circuit 8 is provided at the subsequent stage of the rectifier circuit 6 and voltage detection after rectification is performed, so that the output voltage from the piezoelectric transformer 2 does not become an overvoltage, and the waveform shaping circuit 71. , 72 and the loads 31, 32 are protected.

(2) Two outputs with shifted timings In this embodiment, the rectangular wave voltage is alternately supplied to the two loads 31 and 32 as follows.
First, an ON / OFF signal is supplied from the control circuit 10 to the first relay 91 to supply and stop the rectangular wave voltage from the waveform shaping circuit 71 to the first load 31. In this case, the waveform shaping circuit 71 has a configuration in which a Zener diode TD and a resistor R are connected in series, and outputs to the loads 31 and 32 are taken out from the intermediate portion thereof, so that when the relay 91 is off, that is, a rectangular wave voltage to the load 31 Is turned off, the predetermined voltage is maintained at the end of the waveform shaping circuit 71 on the piezoelectric transformer 2 side until the voltage drop due to the resistor R is completed.

  In this state where the predetermined voltage is maintained, the voltage from the piezoelectric transformer 2 is applied to the resistance R side end of the second waveform shaping circuit 72. At this time, the ON signal for the relay 92 is supplied from the control circuit 10 in synchronization with the OFF signal for the relay 91. The on signal is inverted or phase shifted in the signal processing device 11 and then supplied to the relay 92. The relay 92 is turned on based on the inverted signal or the phase shifted on signal, and the waveform shaping circuit 72 A rectangular wave voltage is supplied to the second load 32.

  In the same manner, each time the relays 91 and 92 are repeatedly turned on / off, the piezoelectric elements for the waveform shaping circuits 71 and 72 are applied by the voltage drop function that requires a certain time of the resistance R provided in the waveform shaping circuits 71 and 72. Since the output from the transformer 2 can be maintained, the output of the rectangular wave voltage to the two loads 31 and 32 can be alternately switched by one piezoelectric transformer.

[1-3. effect]
(1) Since the waveform shaping circuits 71 and 72 have a configuration in which a Zener diode TD and a resistor R are connected in series, two rectangular wave voltages with different timings can be output from one piezoelectric transformer 2. As a result, a low-cost and high-performance switching type high-voltage power supply circuit can be provided by reducing the number of parts by reducing the piezoelectric transformer 2 and simplifying the circuit configuration.

(2) According to the present embodiment, the output voltage value of the piezoelectric transformer 2 can be shortened in the rise time and the fall time. For example, when only the relays 91 and 92 are provided, as shown in FIG. 4, although the fall time is shortened, it takes time to rise, and the voltage above the waveform of the output voltage value cannot be maintained. On the other hand, in this embodiment, since the output voltage value of the piezoelectric transformer 2 is twice the load voltage value, the output voltage draws a waveform as shown by the dotted line in FIG. 5 and rapidly rises to its peak. . As a result, the rise time required from the ground potential to the load voltage value is halved compared to FIG.

  In this state, when the portion of the output voltage exceeding the load voltage value is cut by the waveform shaping circuits 71 and 72, a rectangular wave having a flat load voltage value can be obtained as shown by the solid line in FIG. As a result, the load 31, 32 is applied with a rectangular wave voltage having a fast rising and falling speed and a load voltage value continuing for a predetermined time.

(3) Since the relays 91 and 92 are provided after the waveform shaping circuits 71 and 72 and the relays 91 and 92 are turned off by the relay control circuit 10, the falling speed of the rectangular wave is improved. , 32, etc., can be output to the loads 31, 32 with a rectangular wave excellent in falling response. Further, since the relays 91 and 92 are provided at the subsequent stage of the waveform shaping circuits 71 and 72, the withstand voltage of the relays 91 and 92 can be lowered by the voltage stepped down by the waveform shaping circuits 71 and 72.

(4) In this embodiment, zener diodes are used as the waveform shaping circuits 71 and 72. Therefore, compared to other waveform shaping circuits using resistors or the like, the rising speed is improved and load power loss is reduced. effective.

[2. Second Embodiment]
FIG. 6 is a second embodiment of the present invention. In this embodiment, the output voltage value of the piezoelectric transformer 2 is set in the drive circuit of the piezoelectric transformer 2 without feeding back the output voltage from the piezoelectric transformer 2 or the output voltages from the waveform shaping circuits 71 and 72 to the oscillation circuit 4. A circuit 8a is provided. In the present embodiment, since the output value of the setting circuit 8a is the output voltage value desired to be obtained by the piezoelectric transformer 2, the set value is set to, for example, twice the load voltage value.

  According to the present embodiment, since the output voltage is determined by the setting circuit 8a, the clamp value of the output voltage for the loads 31 and 32 is determined without detecting the feedback voltage for the drive circuit.

[3. Other Embodiments]
The present invention is not limited to the above-described embodiments, and includes other embodiments as follows.
(1) Instead of providing the relays 91 and 92 between the waveform shaping circuits 71 and 72 and the loads 31 and 32, the relays 91 and 92 may be provided at other locations on the secondary side of the piezoelectric transformer 2. For example, these circuits may be provided in parallel or in series between the rectifier circuit 6 and the waveform shaping circuits 71 and 72, or between the piezoelectric transformer 2 and the rectifier circuit 6. Relays 91 and 92 can be connected in series to loads 31 and 32.

(2) The output voltage value from the piezoelectric transformer 2 is not limited to twice the load voltage value. The falling speed of the voltage waveform supplied to the loads 31 and 32 changes according to the time constant determined by the capacity and resistance of the loads 31 and 32 or the frequency applied to the loads 31 and 32. Therefore, the output voltage value from the piezoelectric transformer 2 is adjusted so that the flat portion of the rectangular wave continues for the time required by the loads 31 and 32 according to the degree of delay of the falling speed by the loads 31 and 32. .

(3) As the drive circuit for the piezoelectric transformer 2, a known circuit can be used as appropriate in addition to the output value detection circuit 8, the oscillation circuit 5 and the switching circuit 4 as shown in the figure.

(4) Although the piezoelectric transformer 2 has been described as an example of the transformer, a winding transformer can also be used. However, since the piezoelectric transformer 2 is more responsive to the control frequency from the drive circuit, generation of a pulse wave, control of the output voltage, etc. can be performed easily and accurately.

(5) As the relays 91 and 92, semiconductor relays, semiconductor switches, and other switches can be used. In the present invention, the configuration is not particularly limited as long as the relay control circuit 10 repeatedly turns on and off at a predetermined frequency with an off signal.

(6) As the relay control circuit 10 and / or the signal processing circuit 11, a circuit that outputs an on / off signal, a waveform signal of a predetermined frequency, and the like can be used, and a control signal is supplied from the outside of the switching type high-voltage power supply circuit. The control signal may be generated in the switching type high-voltage power supply circuit.

(7) The present invention has at least first and second waveform shaping circuits, a load, and a relay, and is a switched high-voltage power supply that connects more waveform shaping circuits and loads in parallel to one piezoelectric transformer. Circuits are also included.

DESCRIPTION OF SYMBOLS 1 ... Input power supply 2 ... Piezoelectric transformer 31, 32 ... Load 4 ... Switching circuit 5 ... Oscillation circuit 6 ... Rectification circuit 71, 72 ... Waveform shaping circuit 8 ... Output value detection circuit 8a ... Output voltage value setting circuit 91, 92 ... Falling processing relay 10 ... relay control circuit 11 ... signal processing circuit

Claims (3)

An input power supply that outputs a constant voltage;
A transformer that converts a voltage from the input power source into a predetermined pulse wave and outputs a voltage value higher than a load voltage value;
A drive circuit for the transformer;
First and second waveform shaping circuits connected in parallel to the secondary side of the transformer and cutting the output voltage value of the transformer into a load voltage value and outputting a rectangular wave ;
In the first and second waveform shaping circuit, a resistor arranged in series before Quito lance side of the take-out portion of the output voltage, the zener diode provided in series with the ground side of the take-out portion,
First and second loads connected to the secondary side of the transformer via the first and second waveform shaping circuits;
First and second falling processing relays provided between the secondary side of the transformer and the first and second loads;
A relay control circuit that outputs an off signal to the first and second falling processing relays when the rectangular wave falls;
A signal processing circuit provided in the relay control circuit for inverting or phase-shifting an off signal supplied to one of the first and second falling processing relays;
A switching type high-voltage power supply circuit.   The switched high-voltage power supply circuit according to claim 1, wherein the transformer is a piezoelectric transformer.   The switched high-voltage power supply circuit according to claim 1 or 2, wherein an output voltage value of the transformer is twice or more a load voltage value.

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