JPH11178350A - Power supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply device for assuring stable activation of a load while preventing eddy currents from occurring at activation. SOLUTION: A power supply device 10 is provided with a solar cell 11, an inverter main circuit 12 for converting DC power that is outputted from the solar cell 11 to an AC power, and a control part 14 for controlling the output voltage of the inverter main circuit 12. When the power supply device 10 is activated, the control part 14 controls an output voltage from the inverter main circuit 12 to a value, that is lower than the rated voltage of the power supply device 10 and at the same time from a specific voltage for enabling a household appliance 9 mounting a microcomputer without any reset circuit 91 to gradually to a rated voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device for converting a DC power supply such as a solar cell into AC through an inverter and supplying AC power to a load.

[0002]

2. Description of the Related Art Generally, in a power supply device having a DC power supply for supplying AC power, DC power output from the DC power supply is converted into AC power by an inverter main circuit provided in the device. This inverter main circuit is usually controlled by a microcomputer (hereinafter simply referred to as a microcomputer), and the control of the output voltage at the time of startup is also performed based on a voltage amplitude command signal output from the microcomputer. As the voltage amplitude command signal, for example, a signal as shown in FIG. 4 is known.

[0003] When the voltage output from the DC power supply is within a predetermined range, the microcomputer operates after the power supply device is started.
The voltage amplitude command value shown in FIG. 4 so that the voltage output from the inverter main circuit becomes the rated voltage of the power supply device, for example, 100 V (effective value, similarly, the AC voltage value is an effective value unless otherwise specified). B is output.

[0004] However, when the output start voltage of the inverter main circuit is set to the rated voltage of the power supply based on the voltage amplitude command value B at the time of starting the power supply, the start voltage is high and the inverter main circuit is not connected to the output start voltage. Overcurrent accompanying the start of switching is likely to occur. When such an overcurrent occurs, a method is generally adopted to shut off the inverter main circuit to protect the circuit. At that time, an overvoltage is generated at the output terminal of the inverter main circuit, that is, the output terminal of the power supply device due to the interruption of the overcurrent, and the overvoltage may be applied to the load connected to the output terminal. Was.

Therefore, conventionally, as shown by a solid line in FIG. 4, the voltage amplitude command signal is controlled so as to gradually increase from the voltage amplitude command value 0 to the same command value B over 10 seconds, for example. The output voltage of the power supply is 0V to
Similarly, soft start control for gradually increasing the voltage to 100 V over 10 seconds was performed.

On the other hand, when a household electric appliance is used as a load connected to the power supply device, for example, a microcomputer (hereinafter referred to as a home electric appliance microcomputer) mounted on the electric appliance is equipped with a reset circuit. Some are and others are not. In this reset circuit, the power supply of the home appliance microcomputer, for example, the output voltage (DC) of the AC / DC conversion power supply is set to the steady operating voltage of the home appliance microcomputer, for example, 5 V
Then, an ON signal is transmitted to the home appliance microcomputer, and the home appliance microcomputer is started by the signal.

In the case of a home appliance microcomputer not equipped with the reset circuit, the output voltage of the AC / DC conversion power supply is directly applied to the home appliance microcomputer, and the microcomputer is started.

[0008]

By the way, when a device equipped with a home appliance microcomputer not equipped with the reset circuit is connected as a load to the above-described power supply device having a soft start function, and the power supply device is started, the same power supply device is used. It is conceivable that a voltage equal to or lower than the steady operating voltage is applied to the home appliance microcomputer via the AC / DC conversion power supply at the time of startup. That is, depending on the input voltage to the AC / DC conversion power supply, the output voltage of the AC / DC conversion power supply may not reach the steady operation voltage of the home appliance microcomputer, and a voltage lower than the steady operation voltage may be applied to the microcomputer. is there.

When a voltage lower than the normal operation voltage of the home appliance microcomputer is applied to the home appliance microcomputer, the home appliance microcomputer may run away or operate in an unstable manner, and the load device may not be normally operated. There is a possibility that the computer cannot be started.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a power supply device that ensures stable startup of a load while preventing occurrence of overcurrent at startup.

[0011]

A power supply apparatus according to the present invention controls a DC power supply, an inverter main circuit for converting DC power output from the DC power supply to AC, and an output voltage of the inverter main circuit. And a control unit, the control unit comprising, when the power supply device is started, a predetermined voltage that lowers an output voltage from the inverter main circuit below a rated voltage of the power supply device and activates a load. Is controlled so as to gradually increase the rated voltage to the rated voltage.

[0012] More specifically, the load is constituted by a device including a microcomputer, and the predetermined voltage is a voltage enabling normal start-up of the microcomputer.

When a device equipped with a microcomputer having no reset circuit as a load is connected to the power supply having such a configuration and the power supply is started, the output voltage of the power supply becomes normal. The voltage gradually increases from a predetermined voltage enabling the start to the rated voltage of the power supply. Therefore, the microcomputer starts normally.

A power supply unit is connected to a load, is connected to a commercial power system, and is capable of simultaneously supplying AC power to the load and the commercial power system. A power supply device that is operated by switching between an independent operation mode for supplying AC power only to a load in a disconnected state, and only when the independent operation mode is started, the control unit is configured to receive the power from the inverter main circuit. Is controlled so as to gradually increase the output voltage from the predetermined voltage to the rated voltage.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment A first embodiment of a power supply device according to the present invention will be specifically described below with reference to FIGS.

The power supply device 10 according to the first embodiment
As shown in FIG. 1, the configuration of the solar cell 11 is provided as a DC power supply, and an inverter main circuit 12 connected to the solar cell 11 and converting DC power output from the solar cell 11 into AC power. A power output terminal 13 connected to the output terminal of the inverter main circuit 12, and a voltage Vout (hereinafter referred to as an inverter output voltage Vout, the instantaneous value of which is connected to the output terminal of the inverter main circuit 12 at the output terminal of the inverter main circuit 12). And a control unit 14 for controlling the output voltage v). The bridge configuration of the inverter main circuit 12 using the switching elements may be either a single bridge or a multiple bridge.

The control unit 14 includes a main control unit 41
An oscillation circuit 42 for outputting a frequency command signal Sf, and a multiplier 43 connected to the main control unit 41 and the oscillation circuit 42
And a subtractor 44 for calculating a deviation between the output of the multiplier 43 and the inverter output voltage v, and a PWM pulse generation circuit 46 connected to the subtractor 44. Further, the control unit 14 outputs, on the output side of the PWM pulse generation circuit 46,
An AND circuit 47 is provided for controlling by the main control section 41 whether or not the output of the PWM pulse generation circuit 46 is input to the inverter main circuit 12.

The main control unit 41 includes a microcomputer, a ROM in which control data and a control program are stored, a RAM in which operation data is temporarily stored, level conversion and waveform shaping of signals input / output to / from the main control unit 41, and the like. I / O interface that performs analog / digital conversion, an A / D converter that performs analog / digital conversion of signals input / output to / from the main control unit 41, and a D / A
A converter (both not shown) and the like are provided.

The output voltage Vdc of the solar cell 11 is converted to a predetermined level by a voltage converter (not shown) and input to the main controller 41. The main control unit 41 (specifically, a microcomputer) outputs the output voltage Vdc of the solar cell 11.
When the power supply device 10 recognizes that the
And outputs a control signal for activating. Further, when the output voltage Vdc is recognized to have fallen below the specified voltage, a control signal for stopping the power supply is output. That is, the power supply device 10 is automatically started and stopped by the main control unit 41 in accordance with the output voltage Vdc of the solar cell 11.

Further, the inverter output voltage v is similarly converted to a predetermined level by a voltage converter (not shown) and input to the main controller 41.
Are monitored and controlled by the main control unit 41.

Next, the operation of the power supply device 10 having such a configuration at the time of startup will be described with reference to a time chart shown in FIG. Here, when the power supply device 10 is activated, the power supply device 10 outputs the output voltage Vd of the solar cell 11 as described above.
Since the automatic start and the automatic stop are performed by the main control unit 41 in accordance with c, the case where the operation is automatically stopped once and then restarted is also included.

As shown in FIG. 1, the power supply device 10 is connected to a home electric appliance 9 equipped with a microcomputer 92 without a reset circuit 91 as a load. It is assumed that the power switch 94 of the home electric appliance 9 is in an ON state.
As shown in FIG. 1, the home electric appliance 9 is provided with a microcomputer power supply 93 for driving a microcomputer 92. The microcomputer power supply 93 is connected to an inverter output voltage v input to the home electric appliance 9. And outputs a DC voltage Vsr for driving the microcomputer 92.

Now, at time t0 shown in FIG.
Output voltage Vdc of the power supply 10
Is started, the main control unit 41 starts outputting the voltage amplitude command signal SV at the time of start shown in FIG.
The frequency command signal Sf is output from the oscillation circuit 42 to the other input terminal of the multiplier 43.

Here, the frequency command signal Sf is a sinusoidal signal output from the oscillation circuit 42, and its frequency is a commercial frequency, for example, a predetermined frequency of 50 Hz. As shown in FIG. 2A, the voltage amplitude command signal Sv at the time of startup rises at a command value A at the start time t0 of the power supply device 10, and thereafter, the first time until the time t1 shown in FIG. For τ seconds (for example, 5 seconds), the command value gradually increases linearly from the command value A to the command value B, and thereafter, the command value B
Is a signal that is constant at Based on the voltage amplitude command signal SV, when the power supply device 10 is started, the inverter output voltage V
out is, for example, from the output start voltage Vst of 50 V (corresponding to the command value A) gradually over τ seconds thereafter.
100V which is 0 rated voltage Vrv (corresponding to command value B)
It is controlled so that

Here, the command value A is such that, when the output start voltage Vst of the inverter based on the command value A is applied to the microcomputer power supply 93, the output voltage Vsr of the microcomputer power supply 93 is used to normally start the microcomputer 92 and The voltage is set in advance so as to be a voltage (hereinafter, a microcomputer steady operation voltage) Vmc enabling normal operation. Therefore, as shown in FIG. 2C, the microcomputer power supply 93 can output the microcomputer steady operation voltage Vmc simultaneously with the activation of the power supply device 10. At this time, the microcomputer 92 sets the reset circuit 9
Even if the device 1 is not installed, the device is reliably started, and the home electric device 9 also normally shifts to the active state. The microcomputer steady operating voltage Vmc has a predetermined width, not a constant value, as shown by hatching in FIG.

As described above, since the output start voltage Vst of the inverter is lower than the rated voltage Vrv, the occurrence of overcurrent in the inverter main circuit 12 is prevented when the inverter main circuit 12 starts switching. Is done.

The waveform of the voltage amplitude command signal SV shown in FIG. 2A at the time of startup is obtained by converting the waveform data stored in the ROM of the main control section 41 into a D / A conversion signal provided in the main control section 41. It is sequentially converted and generated by a device (not shown). This waveform data is R data as digital data corresponding to the waveform shape of the voltage amplitude command signal SV at the time of start shown in FIG.
It is stored in the OM.

Next, in the multiplier 43, the voltage amplitude command signal SV is multiplied by the voltage frequency signal sf to generate a voltage command signal vs. Then, in the subtractor 44,
The deviation εv is calculated based on the input of the voltage command signal vs and the inverter output voltage v.
Is amplified by the amplifier 45 and the PWM pulse generation circuit 4
4 is input. The inverter output voltage v input to the subtractor 44 is converted to a predetermined voltage by a transformer (not shown).

Then, the PWM pulse generation circuit 46 generates a PWM pulse based on the amplified deviation εv, and outputs the PWM pulse to one input terminal of the AND circuit 47. When the PWM ON signal is input from the main control unit 41 to the other input terminal of the AND circuit 47, the PWM pulse is output from the AND circuit 47 to the inverter main circuit 12. In addition, this PWM
The ON signal is output from the AND circuit 4 from time t0 shown in FIG.
7 is input. Then, the switching of the inverter main circuit 12 is controlled based on the PWM pulse, and a desired inverter output voltage Vout corresponding to the voltage amplitude command signal SV at the time of starting is output. Here, the control unit 14
Thus, output voltage follow-up control for feeding back the inverter output voltage v and following the voltage command signal vs (voltage amplitude command signal SV) is performed.

The above operation is repeated, and the waveform of the inverter output voltage v at the time of startup is as shown in FIG. In FIG. 2B, the inverter output voltage v
Is schematically shown. That is, in power supply device 10 of the present embodiment, when the power supply device 10 is started, a desired inverter output voltage Vout corresponding to voltage amplitude command signal SV is output from inverter main circuit 12. And
The output start voltage Vst of the inverter output voltage Vout
Is a value that is lower than the rated voltage Vrv of the power supply device 10 and that enables the home appliance 9 to smoothly transition to the active state while ensuring normal startup of the microcomputer 92.

Next, effects obtained by the above-described first embodiment will be described below. In the present embodiment, when the power supply device 10 is started,
The output voltage Vout from the inverter main circuit 12 is lower than the rated voltage Vrv of the power supply device 10 and gradually becomes higher than the starting voltage Vst from which the home appliance 9 can be smoothly shifted to the active state by ensuring the normal start of the microcomputer 92. Control is performed so as to increase to the voltage Vrv. Therefore, it is possible to prevent the occurrence of an overcurrent in the inverter main circuit 12 when the power supply device 10 is started, and to control the microcomputer 9 mounted on the home appliance 9 connected to the output terminal 13 of the power supply device 10.
Even if the microcomputer 2 is not equipped with the reset circuit 91, the microcomputer 92 can be started normally. as a result,
The home appliance 9 can be smoothly shifted to the active state, and stable startup of the home appliance 9 can be guaranteed.

[Second Embodiment] Hereinafter, a second embodiment of the power supply device according to the present invention will be specifically described with reference to FIG.

The power supply device 10 shown in the first embodiment is configured to independently supply AC power to the household electric appliance 9 as a load, whereas the power supply device 10 shown in FIG.
The power supply device 20 according to the present embodiment can similarly supply electric power to the household electric appliance 9 alone and can simultaneously supply AC electric power to the household electric appliance 9 and the commercial electric power system 7 while being connected to the commercial electric power system. It is configured to be possible. for that reason,
Among the components of the power supply device 20, the same components as those of the power supply device 10 are denoted by the same reference numerals, description thereof will be omitted, and differences will be described below.

The power supply device 20 according to the second embodiment
As shown in FIG. 3, a configuration of the solar cell 21, an inverter main circuit 22 connected to the solar cell 21 and converting DC power output from the solar cell 21 into AC power,
A power output terminal 13 connected to the output terminal of the inverter main circuit 22; an inverter output voltage Vout and an inverter output current Iou connected to the inverter main circuit 22;
and a control unit 24 for controlling t. In addition,
The bridge configuration using the switching elements of the inverter main circuit 22 may be either a single bridge or a multiple bridge, like the inverter main circuit 12.

The control unit 24 includes a main control unit 61
An oscillator circuit 42, a multiplier 63 to which the outputs of the first switch 71 and the second switch 72 are input,
A subtractor 64 for calculating a deviation between an output of the multiplier 63 and a signal from the third switch 73; a PWM pulse generating circuit 66 connected to an output side of the subtractor 64;
An ND circuit 47 and the like are provided. The control unit 24 includes:
A band-pass filter (BPF) 6 for extracting only the commercial frequency component from the inverter output voltage v including the harmonic component
9. Current transformer 82 for detecting inverter output current i (instantaneous value), output voltage Vdc of solar cell 21 and main controller 6
A subtractor 68 and the like for calculating a deviation from the operating point command signal PV output by 1 are provided.

The main control section 61 is constructed in the same manner as the main control section 41, and has an output voltage Vdc of the solar cell 21 and an output current Idc of the solar cell 21 converted to a predetermined level by the current transformer 81. Is entered.

The output terminal 13 of the power supply device 20 is connected to the interconnection breaker 8 and the fourth switch 74. The main control section 61 controls the interconnection breaker 8 and the fourth switch 74 to control the power supply 2.
0 is switched between a normal operation (system interconnection operation) mode and an independent operation mode.

Next, the operation of the power supply device 20 having such a configuration at the time of startup in the system interconnection operation mode will be described. In this grid connection operation mode, since the commercial power system 7 is used as a voltage source, the main control unit 6
1 controls the output current of the power supply device 20, that is, the inverter output current Iout, when the power supply device 20 is started.

In the system interconnection operation mode, the main control unit 61 controls all of the first switch 71, the second switch 72, the third switch 73, and the fourth switch 74 as shown in FIG. Is connected to the “a” side, the circuit breaker 8 is closed, and the power supply device 20 and the commercial power system 7 are connected.

Now, in this state, when the output voltage Vdc of the solar cell 21 reaches a predetermined specified voltage and the power supply device 20 is started, the main control unit 61 sends the operating point command signal P to the subtractor 68.
V is output. The operating point command signal PV is used to perform the maximum power point tracking control of the solar cell 21.
Is a signal for instructing the voltage operation point (operating voltage) of the above. The main controller 61 calculates an operating voltage that maximizes the output power of the solar cell 21 based on the output voltage Vdc and the output current Idc of the solar cell 21, converts the operating voltage to a predetermined level, and outputs the converted level.

The output voltage Vdc of the solar cell 21 converted to a predetermined level is input to the subtractor 68, and the deviation from the operating point command signal PV is calculated. This deviation is input to one input terminal of the multiplier 63 via the first changeover switch 71, and the other input terminal of the multiplier 63 receives the inverter output voltage v converted to a predetermined level at the BPF6.
9 and via the second switch 72. Then, in the multiplier 63, the inverter output voltage v (waveform)
And the deviation are multiplied to generate a current command signal is. Here, the current command signal is at the time of starting is a command signal for gradually increasing the inverter output current Iout from 0 (zero) and performing a soft start. And the subtractor 6
In step 4, the deviation εi is calculated based on the current command signal is and the inverter output current i converted to a predetermined level.

The PWM pulse generation circuit 66 generates a PWM pulse based on the amplified deviation εi,
The PWM pulse is output to one input terminal of the AND circuit 47. As described above, when the PWM ON signal is input from the main control unit 61 to the other input terminal of the AND circuit 47, the PWM pulse is output from the AND circuit 47 to the inverter main circuit 22. Then, the switching of the inverter main circuit 22 is controlled based on the PWM pulse, and the current command signal is
, A desired inverter output current i is output.
That is, here, the control unit 24 performs output current follow-up control in which the inverter output current i is fed back to follow the current command signal is.

As described above, when the power supply device 20 is started in the normal operation (system interconnection operation) mode, the soft start control of the inverter output current Iout is performed. Next, an operation at the time of startup of the power supply device 20 in the independent operation mode will be described.

In the independent operation mode, the main controller 61 controls the output voltage of the power supply device 20, that is, the inverter output voltage V, as in the case of the main controller 41.
out is controlled.

In the independent operation mode, the main controller 61
Are the first switch 71 and the second switch 7
2, all the changeover switches of the third changeover switch 73 and the fourth changeover switch 74 are switched to the "b" side, and the breaker 8 for disconnecting the interconnection is set to "open", and the power supply device 20 is disconnected from the commercial power system 7. Line up. In this state, the power supply 20
Is activated, the power supply device 20 operates in the same manner as the power supply device 10 shown in the first embodiment.

That is, when the output voltage Vdc of the solar cell 21 reaches a predetermined specified voltage at time t0 shown in FIG. 2 and the power supply device 20 is started, the main control unit 61 sends one input terminal of the multiplier 63 to the input terminal. At the same time as the start-up voltage amplitude command signal SV shown in FIG.
Outputs the frequency command signal Sf to the other input terminal of the multiplier 63. Hereinafter, similarly, the power supply device 20
Is activated in the operation mode shown in FIGS. 2A and 2B.

As described above, in the power supply device 20 capable of such system interconnection, the control as described in the first embodiment is applied only at the time of starting the independent operation mode. . In the independent operation mode of the power supply device 20, the same effect as in the first embodiment, that is, the occurrence of overcurrent in the inverter main circuit 22 when the power supply device 20 is started can be prevented. The microcomputer 9 mounted on the home appliance 9 connected to the output terminal 13 of the device 20
Even if the microcomputer 2 is not equipped with the reset circuit 91, the microcomputer 92 can be started normally. as a result,
The home appliance 9 can be smoothly shifted to the active state, and stable startup of the home appliance 9 can be guaranteed.

Each of the above embodiments can be embodied by changing the configuration as follows. -In the said 2nd Embodiment, it was set as the structure which supplies electric power to the household appliances 9 via the 4th changeover switch 74 at the time of the independent operation mode, However, It is not limited to this, For example, an outlet is provided in the power supply device 20. The home electric appliance 9 may be connected to the lever outlet to supply power to the home electric appliance 9.

In the above-described embodiments, an example is shown in which the voltage amplitude command signal SV at startup is generated by D / A converting waveform data (digital data) stored in the ROM of the main control unit 41. However, it is not limited to this. For example, the voltage amplitude command signal SV at the time of the start may be generated in an analog manner by an integrator and a comparator having a predetermined time constant.

In the above embodiments, the predetermined frequency of the frequency command signal Sf is set to the commercial frequency (50 Hz), but is not limited to the commercial frequency. Same frequency command signal Sf
May be, for example, 20 Hz, 100 Hz, or the like. In this case, the output frequencies of the power supply 10 and the power supply 20 in the independent operation mode are also 20 Hz and 100H.
z, etc. Also, the rated voltage Vr of the power supply units 10 and 20
v is not limited to 100 V, for example, 80 V, 200 V
And so on.

In each of the above embodiments, the configuration has been described in which the inverter main circuits 12, 22 are PWM-controlled by the control units 14, 24, but the present invention is not limited to this. The inverter main circuits 12 and 22 may be configured to be PAM (pulse amplitude modulated) controlled by a control unit, for example.

In each of the above embodiments, the power supply devices 10 and 20 are single-phase power supply devices in which the outputs from the inverter main circuits 12 and 22 are single-phase AC. However, the present invention is not limited to this. Instead, the power supply device may be a multiphase power supply device having a configuration capable of outputting a polyphase alternating current. For example, in the case of outputting three-phase alternating current, each phase may be controlled in the operation mode shown in FIG. Only the phase or two phases may be controlled in the same operation mode.

In each of the above embodiments, an example is shown in which the DC power supply is constituted by the solar cells 11 and 21, but the present invention is not limited to this. For example, the DC power supply may be configured by a storage battery, a fuel cell, or the like.

In the above-mentioned embodiments, the start and stop of the power supply devices 10 and 20 are performed by the DC power supply (the solar cells 11 and 20).
Although the automatic start / stop is performed based on the output voltage of 1), the present invention is not limited to this. For example, a start / stop switch is provided on the power supply to manually start / start the power supply.
It may be configured to stop.

[0055]

According to the present invention, when the power supply is started, the output voltage from the inverter main circuit is lower than the rated voltage of the power supply and gradually rises from a predetermined voltage for activating the load to the rated voltage. Control so that overcurrent can be prevented, and even if a device equipped with a microcomputer without a reset circuit is connected as a load, the device can be started up stably. Can be done.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of a power supply device according to the present invention.

FIG. 2 is a time chart showing an operation mode at the time of starting the power supply device.

FIG. 3 is a block diagram illustrating a power supply device according to a second embodiment of the present invention.

FIG. 4 is a graph showing a voltage amplitude command signal when a conventional power supply device is activated.

[Explanation of symbols]

 10, 20: power supply device 11, 21: solar cell 12, 22: inverter main circuit 14, 24: control unit 41, 61: main control unit 42: oscillation circuit 43, 63: multiplier 46, 66: PWM pulse generation circuit

Claims (3)

[Claims] 1. A power supply apparatus comprising: a DC power supply; an inverter main circuit that converts DC power output from the DC power supply into AC power; and a control unit that controls an output voltage of the inverter main circuit. The control unit controls the output voltage from the inverter main circuit to be lower than the rated voltage of the power supply device and to gradually increase the output voltage from a predetermined voltage that activates the load to the rated voltage when the power supply device is started. A power supply device, characterized in that: 2. The power supply device according to claim 1, wherein the load comprises a device including a microcomputer, and the predetermined voltage is a voltage enabling normal starting of the microcomputer. 3. A normal operation mode in which the power supply device is connected to a load, is connected to a commercial power system, and can simultaneously supply AC power to the load and the commercial power system. A power supply device that is operated by switching between an independent operation mode for supplying AC power only to a load in a state of being disconnected from a power system, and only when the independent operation mode is started, the control unit includes the inverter. 3. The power supply device according to claim 1, wherein the output voltage from the main circuit is controlled so as to gradually increase from a predetermined voltage to a rated voltage.