JP2000232784A - Power supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a power supply device that can continuously supply stable power to a load over an entire output variable range. SOLUTION: A rectifier filtering circuit 18 which is included in a high-voltage power supply part 12 of a high-voltage power supply device 10 is provided with a function for boosting the output voltage of a boosting transformer 16, thus suppressing the boosting rate of the boosting transformer 16, eliminating the need for molding the boosting transformer using an insulating material, and hence molding only the rectifier filtering circuit 18 by the use of the insulating material for forming a mold part 38.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a power supply device,
More specifically, the present invention relates to a power supply device that obtains a power supply output by switching a power supply input to a primary winding of a transformer.

[0002]

2. Description of the Related Art Conventionally, a power supply has been developed for the purpose of stably making an output voltage or an output current of a power supply as described in JP-A-62-279366 consistent with a target value. 6 (A), the voltage monitor signal V generated by the voltage detection circuit 22 is used.
_The voltage monitor value indicated by _mon or the current monitor value indicated by the current monitor signal I _mon generated by the current detection circuit 24 is fed back to the CPU 30 via the A / D converter 36 so that the value matches the target value. Pulse generator 3
4 generated by PWM (Pulse Width Modulation,
(Pulse width modulation) The duty of the signal PWM is controlled,
A so-called digital control type power supply that controls on / off of a switch element 20 for controlling application / non-application of a DC voltage generated by a DC power supply 26 to a step-up transformer 16 by a WM signal PWM is widely known. Have been. In the following description, control for making the voltage monitor value match the target value is called constant voltage control, and control for making the current monitor value match the target value is called constant current control.

[0003] However, such a digital control type power supply has the following problems.

In a power supply device as shown in FIGS. 6A and 6B, an output is generated by repeatedly turning on / off a switching element 20, and the value is determined by the PWM signal for turning on / off the switching element 20. It largely depends on the duty of PWM. That is, the duty is increased when the output is to be increased, and the duty is decreased when the output is to be decreased.

[0005] The problem here is the variable resolution of the duty. In the conventional power supply apparatus of the so-called analog control method as shown in FIG. 6B, the variable resolution of the duty of the PWM signal PWM can be said to be almost infinite.
In the case of the power supply device of the digital control system as shown in (A), since the PWM signal PWM is generated by the pulse oscillator 34 under the control of the CPU 30, the duty can be changed only in a predetermined minimum bit unit.

That is, for example, when the frequency of the reference clock signal of the CPU 30 is 20 MHz, FIG.
As shown in the figure, the period of one pulse is 50 ns. Here, when the pulse oscillator 34 has an 8-bit configuration, one cycle is 256 pulses, and therefore, as shown in FIG. 7B, the time of one cycle is 12.8 μS, and the frequency in this case is about 80 kHz. (= 20 MHz / 256 pulses), and the resolution per bit in this case is about 0.5.
39% (= 100% / 256 pulses).

On the other hand, when the pulse oscillator 34 has a 10-bit configuration, one cycle is 1024 pulses.
As shown in (C), the time of one cycle is 51.2 μS, and the frequency in this case is about 20 kHz (= 20 MHz /
1024 pulses), and the resolution per bit in this case is about 0.098% (= 100% / 1024 pulses).

That is, for example, as described above, the CPU 30
When the frequency of the reference clock signal is 20 MHz and the pulse oscillator 34 has a 10-bit configuration, the duty of the PWM signal PWM is 0.09, as shown in FIG.
As shown in FIG. 8 (B), the output voltage can be changed only in steps, as can be set only in steps of 8%.

Similarly, when the frequency of the reference clock signal of the CPU 30 is 20 MHz and the pulse oscillator 34 has an 8-bit configuration, the duty of the PWM signal PWM can be set only in steps of 0.39%.

Further, as shown by the characteristic T1 in FIG. 9, in the conventional power supply device, the output voltage does not increase linearly with an increase in the duty of the PWM signal, and the duty ratio does not vary with the variable range of the output voltage. Variable range is small. For this reason,
In a voltage range where the output voltage greatly increases in response to an increase in the duty, there has been a problem that the output voltage value largely deviates from the target voltage value and the ripple increases.

The first factor is that a resonance current is generated by the exciting inductance and the stray capacitance of the step-up transformer, which affects the current on the primary winding side of the step-up transformer (hereinafter referred to as the primary current). It is mentioned.

That is, the primary side current of an ideal step-up transformer is in a state of linearly increasing as shown in FIG. 10 (A). ) Is generated, and as a result, the primary current increases while the current value largely fluctuates as shown in FIG.

The second factor is that the exciting inductance is small and a necessary primary current flows with a small duty.

That is, the primary current i _{p of the} step-up transformer
Is obtained by the following equation (1), and when the exciting inductance L of the step-up transformer is small, as shown in FIG.
The slope of the increase in the next-side current i _p becomes steep.

_Ip = (V _in / L) t _on (1) where V _in is the voltage value of the DC voltage applied to the primary winding of the step-up transformer, and t _on is the switch element is turned on. Each period is represented.

As a technique capable of solving the above-mentioned problems, a technique described as a conventional technique in Japanese Patent Application Laid-Open No. 9-149637 discloses a technique in which a snubber circuit is provided on the primary side of a step-up transformer as shown in FIG. By providing and consuming the resonance current, as shown in FIG. 10D, the influence of the resonance current is avoided as much as possible, and the primary side current is increased in a state close to a straight line.

Further, in the technique described as the prior art in Japanese Patent Application Laid-Open No. 9-149637, by adjusting the excitation inductance L of the step-up transformer to be large, as shown in FIG. the slope of the increase in the current i _p is gradual.

Incidentally, in order to increase the exciting inductance L, there are methods such as increasing the number of windings of the transformer and narrowing the gap between the coils.

That is, in the technique described in the prior art of Japanese Patent Application Laid-Open No. 9-149637, a snubber circuit is provided on the primary side of a step-up transformer to consume a resonance current and adjust an exciting inductance. As a result, as shown in FIG. 9, the relationship between the duty and the output voltage (output current) is such that the characteristic T2 is directly proportional and gradual throughout the output range, and the output resolution is improved in the variable range. I have. As a result, the fluctuation range of the output when the duty is changed by the minimum number of bits is reduced, and the above problem can be solved.

However, the DC and high voltage power supply has a problem that the relationship between the duty and the output is further deteriorated.

That is, as shown in FIG. 13, in the high-voltage power supply section 112 of the conventional DC high-voltage power supply, the step-up transformer 16 and the components on the secondary winding side (the rectifying and smoothing circuit 11) are used.
8, a resistance 86 as a dummy load, an output terminal 84), a high potential difference is generated between the windings of the step-up transformer 16, between the winding and each component, or between the components, and as it is, a leak or the like is generated or insulation occurs. As a countermeasure against this, the step-up transformer 16 and the components on the secondary winding side are arranged in a resin case, and molded with an insulating material.
38 had been formed.

[0022]

However, in the technique of molding the step-up transformer and components on the secondary winding side with an insulating material, the output resolution at low duty is deteriorated, and when the output is variable, the output is reduced. However, there is a problem in that the ripple becomes large in a small area, or the deviation from the target set value becomes large.

That is, when the step-up transformer and the parts on the secondary winding side are molded with an insulating material, the distributed capacity of the step-up transformer (mainly, the primary winding and the secondary winding) is caused by hardening of the insulating material.
The capacity between the secondary winding and the secondary winding increases. Therefore, FIG.
As shown in (A), an inrush current is generated every time the switch element is turned on, and the output resolution at low duty is deteriorated due to the inrush current. If the output is variable, the output is small. As a result, the ripple increases and the deviation from the target set value increases.

FIG. 15 shows a case where a field effect transistor (FET) is used as a switching element, a resonance current removing circuit is not provided on the primary side of the step-up transformer, and the step-up transformer and the rectifying and smoothing circuit are molded with an insulating material. 5 shows an example of the measurement results of the drain-source voltage of the switch element (the switching signal of the step-up transformer) and the primary current.

As shown in the figure, in the primary side current in this case, when the voltage between the drain and the source drops, that is, when the switch element is turned on, a large rush current occurs, and thereafter the value greatly fluctuates. While increasing.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problem, and has as its object to provide a power supply device capable of constantly supplying stable power to a load in an entire output variable range. .

[0027]

According to another aspect of the present invention, there is provided a power supply device provided on a primary winding side of a transformer and a power supply for a primary winding of the transformer. A power supply device comprising: switch means for switching an input; and boosting means provided on a secondary winding side of the transformer and boosting a voltage on a secondary winding side of the transformer. A part or all of the transformer is molded with an insulating material, and the transformer is excluded from the object of molding.

According to the power supply device of the first aspect, the power supply input to the primary winding of the transformer is switched by the switching means provided on the primary winding side of the transformer. This induces a voltage on the secondary winding side of the transformer,
The voltage is boosted by boosting means provided on the secondary winding side of the transformer.

Here, in the power supply device according to the first aspect, part or all of the boosting means is molded with an insulating material, and the transformer is excluded from molding.

That is, in the present invention, the step-up rate of the transformer can be suppressed low by providing the step-up means on the secondary winding side of the transformer. In addition, the transformer does not need to be molded with an insulating material, since it is possible to prevent the occurrence of electrical breakdown.

The insulating material is a silicon material,
An epoxy material or the like can be used.

As described above, according to the power supply device of the first aspect, since the booster is provided on the secondary winding side of the transformer and the transformer is excluded from the object of molding,
The distribution capacitance of the transformer can be reduced, and a stable output can always be obtained within the output variable range.

According to a second aspect of the present invention, there is provided a power supply device, comprising: a step-up transformer; a DC power supply for generating a DC power supply input to be supplied to a primary winding side of the transformer; and a secondary winding of the transformer. Boosting means for rectifying and smoothing the alternating output generated on the side and boosting and outputting the output, and switch means for interrupting the DC power input supplied from the DC power supply to the primary winding in accordance with a pulse width modulation signal. And detecting means for detecting the magnitude of the output from the boosting means, and control means for controlling the duty of the pulse width modulation signal such that the magnitude of the output matches a preset target value. A power supply device comprising: a part or the whole of the step-up means is molded with an insulating material; and the transformer is excluded from the object of molding.

According to the second aspect of the present invention, the magnitude of the output from the boosting means for rectifying and smoothing the alternating output generated on the secondary winding side of the boosting transformer and boosting and outputting the output is detected. The duty of the pulse width modulation signal is controlled by the control unit such that the magnitude of the detected output is equal to a preset target value.

At this time, a DC power supply is supplied from the DC power supply to the primary winding side of the transformer, and the primary winding side is supplied according to the pulse width modulation signal generated by the control by the control means. The DC power input supplied to the switch is interrupted by the switch means.

That is, when the magnitude of the output from the boosting means controlled to match the target value is the magnitude of the output voltage, the constant voltage control is performed by the boosting means controlled to match the target value. When the magnitude of the output from is the magnitude of the output current, the constant current control is performed by the respective control means.

Here, in the power supply device according to the second aspect, part or all of the boosting means is molded with an insulating material, and the transformer is excluded from molding.

That is, in the present invention, the step-up rate of the transformer can be suppressed low by providing the step-up means on the secondary winding side of the transformer. In addition, the transformer does not need to be molded with an insulating material, since it is possible to prevent the occurrence of electrical breakdown.

The insulating material is a silicon material,
An epoxy material or the like can be used.

According to the power supply device of the second aspect, the booster is provided on the secondary winding side of the step-up transformer, and the transformer is excluded from molding. As in the invention of the third aspect, the distribution capacitance of the transformer can be reduced, and a stable output can always be obtained within the output variable range.

Incidentally, as in the power supply device according to the third aspect,
It is preferable that the transformer according to the first or second aspect further includes a resonance current removing unit that removes a resonance current flowing through the primary winding on the primary winding side of the transformer. Since the resonance current of the transformer can be consumed by the resonance current removing means, a more stable output can be obtained.

[0042]

Embodiments of the present invention will be described below in detail with reference to the drawings.

[First Embodiment] As shown in FIG. 1, a high-voltage power supply unit 10 according to the first embodiment includes a high-voltage power supply unit 12 for generating high-voltage power to be supplied to a load 40, a predetermined DC voltage. And a main control unit 28 for controlling the operation of the entire apparatus.

The high-voltage power supply section 12 includes a resonance current elimination circuit 1
4. Step-up transformer 16, rectifying and smoothing circuit 1 with 1 input and 3 outputs
8, a switching element 20, a voltage detection circuit 22, and a current detection circuit 24. The resonance current removal circuit 14 is connected between the terminals of the primary winding of the step-up transformer 16.
Moreover, to one terminal of the primary winding of the step-up transformer 16 is connected to the output terminals of the DC power supply 26, one of the primary winding of the DC voltage V _in the step-up transformer 16 generated by the DC power source 26 Can be applied to the terminals.

The output terminal of the switching element 20 is connected to the other terminal of the primary winding of the step-up transformer 16, and the terminal of the secondary winding of the step-up transformer 16 is connected to the input terminal of the rectifying and smoothing circuit 18. It is connected. Furthermore, a rectifying and smoothing circuit 1
The input terminals of the voltage detection circuit 22 and the current detection circuit 24 are connected to two of the eight output terminals, respectively.

On the other hand, the main control unit 28 includes a CPU 30 and a PW
The CPU 30 includes a pulse oscillator 34 that generates an M signal PWM, an analog-to-digital converter (hereinafter, referred to as an A / D converter) 36 having two inputs and one output, and a CPU 30.

The output terminal of the arithmetic unit 32 is at the input terminal of the pulse oscillator 34, the input terminal of the arithmetic unit 32 is at the output terminal of the A / D converter 36, and the output terminal of the pulse oscillator 34 is the switch element 20.
Are connected respectively to the input terminals. Therefore, the PWM signal PWM generated by the pulse oscillator 34 can be input to the switch element 20.

Further, the output terminal of the voltage detection circuit 22 is provided at one input terminal of the A / D converter 36, and the output terminal of the current detection circuit 24 is provided at the other input terminal of the A / D converter 36. It is connected. Therefore, the CPU 30 has the voltage detection circuit 22
Each of the voltage monitor value indicated by the voltage monitor signal V _mon generated by the above and the current monitor value indicated by the current monitor signal I _mon generated by the current detection circuit 24 can be input as digital values.

The remaining output terminal of the rectifying / smoothing circuit 18 corresponds to an external load 40 and is connected to the load 40.

The resonance current elimination circuit 14 corresponds to the resonance current elimination means of the present invention, and the step-up transformer 16 corresponds to the transformer of the present invention.
The switch element 20 corresponds to the switching means of the present invention, the rectifying and smoothing circuit 18 corresponds to the boosting means of the present invention, the voltage detecting circuit 22 and the current detecting circuit 24 correspond to the detecting means of the present invention, and the CPU 30 corresponds to the controlling means of the present invention. Equivalent to.

FIG. 2 shows an example of a specific circuit configuration of the high voltage power supply section 12 in the first embodiment shown in FIG.

As shown in FIG.
One terminal of the next winding is connected to the output terminals of the DC power supply 26 via the resistor 50, the DC voltage V _in that is generated by the DC power source 26 is applied.

The switch element 20 in the first embodiment is constituted by an FET 54,
The gate terminal 4 is connected to the output terminal of the pulse oscillator 34 via the resistor 56, and receives the PWM signal PWM generated by the pulse oscillator 34. Also, FET
The gate terminal 54 is grounded via a resistor 58.

On the other hand, the drain terminal of the FET 54 is connected to the other terminal of the primary winding of the step-up transformer 16.
A resistor 52 is connected between the other terminal and one terminal of the primary winding of the step-up transformer 16, and the resistor 52 forms the resonance current removing circuit 14. Also, F
The source terminal of the ET 54 is grounded.

In the switch element 20 configured as described above, the PWM signal PWM input from the pulse oscillator 34
Is high level, the FET 54 is turned on and the PW
When the M signal PWM is at a low level, the FET 54 is turned off. Accordingly, the FET 54 alternately repeats the ON / OFF state in a period corresponding to the duty of the PWM signal PWM, so that the DC voltage from the DC power supply 26 to the primary winding of the step-up transformer 16 is changed according to the duty of the PWM signal PWM. the application / non-application of V _in can be performed alternately.

On the other hand, the rectifying and smoothing circuit 18 is
6 has one terminal connected to one terminal of the secondary winding, and the other terminal of the capacitor 62 has an anode terminal of the diode 64, a cathode terminal of the diode 66, and one terminal of the capacitor 68. The other terminal of the capacitor 68 is an anode terminal of the diode 70, a cathode terminal of the diode 72,
And one terminal of the capacitor 74, and the other terminal of the capacitor 74 is connected to the anode terminal of the diode 76.

The cathode terminal of the diode 76 is connected to the anode terminal of the diode 72 and one terminal of the capacitor 78. The other terminal of the capacitor 78 is connected to the cathode terminal of the diode 70, the anode terminal of the diode 66, and the capacitor 80. , And the other terminal of the capacitor 80 is connected to the diode 6
4 and the other terminal of the secondary winding of the step-up transformer 16. The output terminal of the rectifying / smoothing circuit 18 is connected to an output terminal 84 via an output limiting resistor 82.

That is, the rectifying / smoothing circuit 18 in the present embodiment has a multi-stage boosting configuration (half-wave quintuple voltage rectification), and the alternating current induced in the secondary winding of the boosting transformer 16 is connected to a capacitor and a diode. Rectification and smoothing are performed by the combination, and the magnitude of the output voltage of the step-up transformer 16 is increased approximately five times. Therefore, the rectifying and smoothing circuit 18
The step-up rate by the step-up transformer 16 can be reduced as compared with a case where the step-up rate by the step-up transformer is smaller than approximately five times. That is, when the boosting rate of the rectifying / smoothing circuit 18 is approximately five times as in the present embodiment, as compared with the case where the boosting ratio by the rectifying / smoothing circuit 118 is approximately twice as shown in FIG. The step-up rate by the transformer 16 is approximately 2/5 (5
2).

On the other hand, the operational amplifier 9 is
0, the inverting input terminal of the operational amplifier 90 is connected to the output terminal of the rectifying / smoothing circuit 18 via a resistor 86 functioning as a dummy load, and a capacitor 92, a resistor 94 and a variable resistor 96 are connected in parallel. Operational amplifier 90
, And is connected via a capacitor 98 to a non-inverting input terminal of an operational amplifier 90. The output terminal of the operational amplifier 90 is also connected to the input terminal of the A / D converter 36 via the resistor 100. The non-inverting input terminal of the operational amplifier 90 is grounded.

In the voltage detection circuit 22 configured as described above, the voltage monitor signal V _mon indicating the voltage value (voltage monitor value) of the output voltage of the rectifying / smoothing circuit 18 can be constantly output to the A / D converter 36. it can.

The current detecting circuit 24 includes a resistor 102 having one terminal connected to one terminal of the secondary winding of the step-up transformer 16, and the other terminal of the resistor 102 includes a variable resistor 104. Grounded. One terminal of the resistor 102 is grounded via a capacitor 106 and also connected to an input terminal of the A / D converter 36 via a resistor 108.

In the current detecting circuit 24 configured as described above, the A / D converter 36 converts the current monitor signal I _mon indicating the current value (current monitor value) of the current flowing through the rectifying / smoothing circuit 18.
Can be output at all times.

It is to be noted that the current detection circuit 24 can be reduced when the high voltage power supply 10 performs constant voltage control, and the voltage detection circuit 22 can be reduced when constant current control is performed.

Here, in the high-voltage power supply section 12 of the high-voltage power supply device 10 according to the first embodiment, the rectifying / smoothing circuit 18, the resistor 82, the output terminal 84, and the resistor 86 are arranged on one substrate. The molded portion 38 is formed by molding the substrate with an insulating material (a silicon material in the present embodiment). On the other hand, the step-up transformer 16 is not molded.

That is, the high-voltage power supply unit 1 according to this embodiment
In No. 2, since the step-up rate of the step-up transformer 16 is reduced by increasing the step-up rate of the rectifying / smoothing circuit 18 as described above, a portion having a high potential difference does not occur in the step-up transformer 16, and thus leakage Therefore, it is not necessary to mold the step-up transformer 16 with an insulating material because no step is generated or dielectric breakdown is caused.

Next, as an operation of the first embodiment, control performed by the CPU 30 of the main control unit 28 will be described with reference to FIG. Here, a case where the constant voltage control is performed will be described. Therefore, in this case, the current detection circuit 24 can be eliminated from the high voltage power supply section 12 shown in FIGS.

In step 200 of FIG.
It is determined whether or not 2 is in an operable state, and if not, it stands by until it becomes operable. When the high-voltage power supply unit 12 is in an operable state, the determination in step 200 is affirmed, and the process proceeds to step 202, where the PWM of a predetermined duty is supplied to the pulse generator 34.
By controlling to generate the signal PWM,
The output of the PWM signal PWM of the predetermined duty to the switch element 20 is started. Note that the predetermined duty in the first embodiment is such that a target voltage value (hereinafter, referred to as a target voltage value) in the constant voltage control is a high-voltage power supply unit 1.
2 is obtained in advance by experiment, and the average duty is applied.

In the next step 204, the above step 2
In response to the input of the PWM signal PWM 02, a predetermined time corresponding to the time required for the value of the voltage output from the high-voltage power supply unit 12 to stabilize is waited. In the next step 206, the A / D converter 36, the voltage detection circuit 2
The voltage monitor value V _o indicated by the voltage monitor signal V _mon input from 2 is taken in.

In the next step 208, the voltage monitor value V
_o it is determined whether greater than the target value corresponding to the target voltage value, (negative determination) is not greater whether voltage monitor value V _o and proceeds to step 210 is smaller than the target value Is determined.

[0070] On the other hand, if the voltage monitor value V _o in step 208 is determined to be greater than the target value (in the case of affirmative determination) is after reducing by a predetermined amount the duty of the PWM signal PWM shifts to step 212 Step 216
Migrated to, when the voltage monitor value V _o in step 210 is determined to be smaller than the target value (in the case of affirmative determination) step after increasing by a predetermined amount the duty of the PWM signal PWM shifts to step 214 216. Incidentally, if the voltage monitor value V _o in step 210 is determined to not less than the target value (negative determination) is when the voltage monitor value V _o is equal to the target value,
In this case, the process proceeds to step 216 without changing the duty of the PWM signal PWM.

[0071] That is, the process of step 208 to step 214, the predetermined amount a voltage monitor value V _o by if the voltage monitor value V _o greater than the target value to reduce the duty of the PWM signal PWM by a predetermined amount corresponding values only reduces the voltage monitor value V by reverse the voltage monitor value V _o is the case than the target value small will increase the duty of the PWM signal PWM by a predetermined amount
_o is increased by a value corresponding to the predetermined amount.

In step 216, it is determined whether or not the high-voltage power supply unit 12 is in a state to be stopped. If not (in the case of a negative determination), the process returns to step 204, and Step 214
Are repeated, and when the high-voltage power supply unit 12 is stopped, an affirmative determination is made and the control is terminated.

The output voltage of the rectifying / smoothing circuit 18 is controlled so as to be equal to the target voltage value by the repetition of the steps 204 to 214.

When the constant voltage control is performed as described above,
An example of a duty-output voltage characteristic of the high-voltage power supply device 10 is shown as a characteristic T3 in FIG.

That is, in the high-voltage power supply section 12 of the high-voltage power supply device 10 according to the first embodiment, since the step-up transformer 16 is not molded with an insulating material, the step-up transformer 16
Has a very small distributed capacitance as compared with the prior art which is molded with an insulating material.

Accordingly, the inrush current at the time of switching, which has been a problem in the prior art, becomes very small, as shown in FIG. 14B, for example. The increase in the primary side current of the step-up transformer 16 with respect to the increase in the duty of the PWM approaches an ideal triangle, and accordingly, the relationship between the duty and the output voltage is controlled by digital control as shown by the characteristic T3 in FIG. Near linear (linear function) within a suitable output range,
In addition, the characteristics have a gentle inclination.

Therefore, a stable output can always be obtained within the output range suitable for the digital control.

As described above in detail, in the high-voltage power supply device according to the first embodiment, the output voltage of the boosting transformer is boosted by the rectifying and smoothing circuit, and the boosting rate of the boosting transformer is suppressed to a small value, so that the insulation with respect to the boosting transformer is reduced. Since the molding is not performed with the material, the distributed capacitance of the step-up transformer can be reduced, and a stable output can always be obtained within an output range suitable for digital control.

Further, in the high-voltage power supply according to the first embodiment, since the resonance current removing circuit is provided on the primary winding side of the step-up transformer, the generation of the resonance current due to the exciting inductance and the stray capacitance of the step-up transformer is prevented. Can be avoided,
A more stable output can be obtained as compared with the case where the resonance current removing circuit is not provided.

[Second Embodiment] Next, referring to FIG.
A second embodiment of the present invention will be described. The second
In the embodiment, another configuration example of the high-voltage power supply unit in the first embodiment will be described. Therefore, the configuration and operation of the second embodiment other than the high-voltage power supply unit are the same as those of the first embodiment, and a description thereof will be omitted. In FIG. 5, the same parts as those in FIG. 2 are denoted by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 5, the high-voltage power supply unit 12 'according to the second embodiment is different from the high-voltage power supply unit 12 according to the first embodiment in that the molding unit that performs molding with an insulating material is the first. The only difference from the first embodiment is that the molded portion 38 in the embodiment is a molded portion 38 'which is a region excluding the capacitor 62 and the diode 64.

That is, the region to be molded with the insulating material is a region where a high potential difference is generated, and it is not always necessary to include the entire rectifying / smoothing circuit 18, and as shown in FIG. However, even when only the latter stage where the potential becomes higher is to be molded, good characteristics substantially similar to those shown by the characteristics T3 in FIG. 4 can be obtained.

As described in detail above, in the high-voltage power supply according to the second embodiment, as in the first embodiment, the output voltage of the boosting transformer is boosted by the rectifying and smoothing circuit and the boosting rate of the boosting transformer is increased. Is reduced so that molding with an insulating material is not performed on the step-up transformer, so that the distributed capacity of the step-up transformer can be reduced, and a stable output can always be obtained within an output range suitable for digital control. At the same time, since the area for molding with an insulating material is narrowed as compared with the first embodiment, cost reduction and space saving can be performed as compared with the first embodiment.

In each of the above-described embodiments, the function is C
Although the case where the PU 30 performs the constant voltage control has been described,
The present invention is not limited to this, and constant current control can be performed.

In this case, the current detection circuit 24 outputs the A / D
The current monitor signal I input via the converter 36
The duty of the PWM signal PWM is controlled so that the current monitor value indicated by _mon (digital value indicating the current value) matches the target value.

Here, when increasing the output current value, P
When increasing the duty of the WM signal PWM and reducing the output current value, the duty of the PWM signal PWM may be reduced. The PWM signal PWM is input to the switch element 20 and is controlled so that the value of the output current coincides with the target value by repeatedly turning on / off the switch element 20 in accordance with the duty of the PWM signal PWM.
In this case, the voltage detection circuit 22 shown in FIGS. 1, 2 and 5 can be omitted.

In each of the above embodiments, the circuit configuration of the rectifying / smoothing circuit 18 shown in FIG. 2 (FIG. 5) is an example, and it is possible to rectify and smooth and alternately boost the alternating output input from the boosting transformer. Any configuration that can be applied can be applied.

In each of the above embodiments, the resonance current removing circuit 14, the switch element 20, and the voltage detecting circuit 2 which constitute the high-voltage power supply section 12 (12 ') shown in FIG. 2 (FIG. 5).
2, and the circuit configuration of the current detection circuit 24 is also an example, and it goes without saying that any circuit configuration can be applied as long as the function of each unit described above can be realized.

In each of the above embodiments, the case where the predetermined duty applied in step 202 of FIG. 3 is an average duty when the voltage of the target voltage value is generated by the rectifying and smoothing circuit 18 will be described. However, the present invention is not limited to this, and any duty may be applied as long as it does not hinder each part constituting the high-voltage power supply device.

In each of the above embodiments, the case where the present invention is applied to a digital control type power supply device has been described. However, the present invention is not limited to this, and the present invention is not limited to FIG. The present invention can also be applied to an analog control type power supply device as shown.

Further, in each of the above embodiments, the case where a silicon material is applied as an insulating material used for molding a rectifying / smoothing circuit or the like has been described. However, the present invention is not limited to this. May be applied.

[0092]

According to the present invention, the booster is provided on the secondary winding side of the transformer and the transformer is excluded from the object of molding, so that the distributed capacitance of the transformer can be reduced and the output can be varied. The advantage is that a stable output can always be obtained within the range.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a schematic configuration of a high-voltage power supply device according to a first embodiment.

FIG. 2 is a circuit diagram illustrating an example of a configuration of a high-voltage power supply unit of the high-voltage power supply device according to the first embodiment.

FIG. 3 is a flowchart illustrating an operation of the high-voltage power supply device according to the first embodiment.

FIG. 4 is a graph showing an example of a duty-output voltage characteristic of the high-voltage power supply according to the first embodiment.

FIG. 5 is a circuit diagram illustrating an example of a configuration of a high-voltage power supply unit of a high-voltage power supply device according to a second embodiment.

FIG. 6 is a diagram showing a schematic configuration of a conventional power supply device;
(A) shows a configuration example of a digital control type power supply device,
(B) is a block diagram which shows the example of a structure of the power supply device of an analog control system, respectively.

7A shows the state of the reference clock signal of the CPU, FIG. 7B shows the state of one cycle and the resolution per bit when the pulse oscillator has an 8-bit configuration, and FIG. 7C shows the state of the pulse oscillator. 6 is a time chart showing a state of one cycle and a resolution per bit in a case of a 10-bit configuration.

FIG. 8A shows a reference clock signal of a CPU and PWM.
It is a time chart which shows the relationship with a signal, (B) is P
9 is a graph illustrating a relationship between a duty of a WM signal and an output voltage.

FIG. 9 is a graph of a duty-output voltage characteristic used for explaining a problem of the related art.

FIGS. 10A and 10B are diagrams used to explain the problems of the prior art, where FIG. 10A shows an ideal waveform of the primary current of the step-up transformer, FIG. 10B shows the waveform of the resonance current, and FIG. (B) is a waveform diagram showing the waveform of the primary current of the boost transformer affected by the resonance current, and (D) is a waveform diagram showing the waveform of the primary current of the boost transformer when the resonance current removing circuit is provided. is there.

FIG. 11 is a waveform chart used for explaining another problem of the related art.

FIG. 12 is a circuit diagram showing an example of a circuit configuration according to the related art.

FIG. 13 is a circuit diagram showing another example of the circuit configuration of the related art.

FIG. 14A is a waveform chart used to explain a problem of the related art, and FIG. 14B is a waveform chart used to explain an effect of the present invention.

FIG. 15 is an actually-measured waveform diagram used for explaining a problem of the related art.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 high voltage power supply device 12, 12 ′ high voltage power supply unit 14 resonant current removing circuit (resonant current removing means) 16 step-up transformer (transformer) 18 rectifying smoothing circuit (step-up means) 20 switch element (switch means) 22 voltage detecting circuit (detecting means) 24) current detection circuit (detection means) 26 DC power supply 28 main control unit 30 CPU (control means) 32 arithmetic unit 34 pulse oscillator 36 A / D converter 38, 38 'mold unit 40 load

Claims (3)

[Claims] A transformer, provided on a primary winding side of the transformer, for switching a power supply input to a primary winding of the transformer, and a switching means provided on a secondary winding side of the transformer; A booster for boosting a voltage on a secondary winding side of the transformer, wherein a part or the whole of the booster is molded with an insulating material, and the transformer is excluded from a molding target. A power supply device characterized in that: 2. A step-up transformer, a DC power supply for generating a DC power supply input for supplying to a primary winding side of the transformer, and an alternating output generated on a secondary winding side of the transformer, Boosting means for smoothing, boosting and outputting; switching means for intermittently inputting a DC power supply supplied from the DC power supply to the primary winding according to a pulse width modulation signal; A power supply device comprising: a detection unit that detects a magnitude; and a control unit that controls a duty of the pulse width modulation signal so that the magnitude of the output matches a preset target value. A power supply device characterized in that part or all of the booster is molded with an insulating material, and the transformer is excluded from molding. 3. The power supply device according to claim 1, further comprising a resonance current removing unit for removing a resonance current flowing through the primary winding on a primary winding side of the transformer. .