JPS6277860A - power supply - Google Patents

Abstract

PURPOSE:To conduct soft starting, through which stress is not given to a main switching element, by detecting the state of an output and reducing an output from a chopper in response to the state of the output. CONSTITUTION:When a power supply is turned ON, a transistor Qss is turned OFF, the emitter resistance of a transistor Q1b is brought to a value R3 larger than that on normal lighting, and an output from an inverter circuit 5 is lowered by utilizing a voltage drop by the resistance, thus preventing the cold start of a fluorescent lamp F. When the emitter resistance of the transistor Q1b increases, the quantity of a base driven in the transistor Q1b reduces, the saturation of a transformer T1 is quickened while the storage time is shortened and oscillating frequency is augmented, and an output from the inverter circuit 5 is made lower than that due to the voltage drop of the emitter resistance.

Description

Detailed Description of the Invention [Field of the Invention] The present invention includes a step-up chopper and an inverter, and is capable of handling low frequency AC power such as a commercial power supply, or higher frequency (
For example, the present invention relates to a power supply device that generates power of 20 to 50KH2), and particularly relates to a power supply device suitable for connecting a discharge lamp as a load and using it as a discharge lamp lighting device.

[Background of the Invention] A high-frequency lighting type discharge lamp lighting device has a soft start function that keeps the output voltage low for a predetermined period of time after power is turned on, a function that reduces the output V20 during no-load, and a function that reduces the load short-circuit current of 12 seconds. Various functions are provided. However, in conventional devices, dedicated switching elements such as transistors and SIRIS were added just to realize such functions (for example,
105996).

[Object of the invention] The object of the present invention is to solve the problems of the conventional type described above,
Based on the concept of using J-3 in a step-up chopper discharge lamp lighting device, the switch element for the chopper can also be used as a switch element for each of the above functions, and has a simple configuration that does not affect the lighting characteristics of the lamp. The purpose of this invention is to reduce the load short circuit current 12s, reduce the no-load voltage V20 without affecting starting, or realize a soft start without stressing the main switching element.

[Explanation of Examples] Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 shows a circuit configuration of a discharge lamp lighting device according to an embodiment of the present invention. The device shown in the figure converts AC input from an AC power supply 1 into a pulsating output (DC conversion) using a rectifier circuit 3.
This pulsating output is flattened or smoothed and outputted by a step-up chopper circuit 4, and converted into a high-frequency current by a series inverter circuit 5 consisting of 5EPP switching transistors Qla and Qlb, and then sent to an output terminal 6. It lights up the connected fluorescent lamp F.

The chopper circuit 4 includes an inductor Lcp and a diode Dcp connected in series between the positive output terminal of the rectifier circuit 3 and the positive input terminal of the inverter circuit 5.
Smoothing capacitor CCI connected in parallel to the output terminal of
), MO8 type field effect transistor Qcp, etc. Capacitors C81, C82 and diode D81. D82 constitutes a voltage doubler rectifier circuit 8a, which doubles and rectifies a high frequency voltage generated in a secondary winding W2b of a current transformer T2 of an inverter circuit 5, which will be described later. This rectified output is transmitted to the trough 1 through resistors R41 and R42.
applied to the gate of star Qcp. This transistor Q
The gate of cp is connected to the collector of transistor Q41 via diode D43. transistor Q
The base of 41 is resistor R43 and Zener diode 2
Transistor Qla of inverter circuit 5 via 041
It is connected to the connection point of and 01b.

In this chopper circuit 4, when the inverter circuit 5 generates a high frequency output, the transistor QCI) is driven with direct current by the voltage doubler rectified output and turned on, and the output voltage is changed to the Zener diode ZD41 for each cycle of the high frequency output of the inverter circuit 5. By turning on the transistor Q41 while the Zener voltage exceeds the Zener voltage, the transistor Qcp is turned off. Thereby, the transistor Qcp is turned on and off in synchronization with the oscillation frequency of the inverter circuit 5. When transistor Qcp turns on, inductor Lap is energized and electromagnetic energy is stored. Then, when the transistor Qcp is turned off, the electromagnetic energy accumulated in the inductor LCp is transferred to the inductor lcρ and the diode D.
cp, is released in the path of the inverter circuit 5 and the rectifier circuit 3. Capacitor CCp smoothes the current supplied to inverter circuit 5. This output current is mainly determined by the on-duty of the transistor Qcp, and is determined by the on-duty of the transistor Qcp.
It is almost independent of the output voltage. Moreover, if the output voltage of the inverter circuit 5 is high, the Zener diode ZD
41 and transistor 41 become longer, and the on-duty of transistor Qco becomes smaller. Conversely, if the output voltage of the inverter circuit 5 is low, the on-duty of the transistor QCI becomes large. For this reason,
The charging current to the smoothing capacitor Ccp is stabilized to some extent, the smoothness of the DC output to the inverter circuit 5 is high, and the input power factor from the AC power supply 1 to the rectifier circuit 3 can be made high.

In the inverter circuit 5, J3 includes a saturable feedback transformer T2, which has one negative winding W21 and two oppositely wound secondary windings W2a and W2b.

- The secondary winding W21 is inserted in series with the output terminal 6, detects the load current flowing therethrough, and generates corresponding secondary voltages in opposite phases to each of the secondary windings W2a and W2b. The secondary winding W2a is the switching transistor Q1
A is connected to the input terminal of the base drive circuit 5a, and the output terminal of the base drive circuit 5a is a switching transistor,
Connected to the base of Qla.

Similarly, the secondary winding W2b is connected to the base of the switching transistor Q1tl via the base drive circuit 5b.

The fluorescent lamp F is AC-connected between the output terminal 6 of the inverter circuit 5 and the DC output terminal of the chopper circuit 4 via a choke coil CH.

This device further includes a series circuit from the positive DC output terminal of the chopper circuit 4 to the negative DC output terminal of the chopper circuit 4 via the resistor R1 and the capacitor C1, and a connection point between the resistor R1 and the capacitor C1. A starting circuit for the inverter circuit 5 is formed by a relaxation oscillation circuit including a bidirectional thyristor SS connected in series from J to the base of one switching transistor Q1b. Note that the diode D1, which is forward-connected between the connection point J and the collector of the switching transistor Q1b, keeps the charging voltage of the capacitor C1 below the breakdown voltage of the bidirectional thyristor SS after the inverter is started, and the startup circuit operates. This is to prevent the inverter from malfunctioning.

When the AC power supply 1 is turned on in the device shown in FIG. 1, a rectified (pulsating current) output is generated from the rectifier circuit 3.

This pulsating output is smoothed by an L-shaped filter consisting of an inductor LCI) and a capacitor Ccp of the chopper circuit 4, and a DC voltage approximately at the peak value of the AC power supply voltage is generated at the output end of the chopper circuit 4.

As a result, charge begins to accumulate in the capacitor C1 via the resistor R1. When the potential at the connection point J exceeds the breakdown voltage of the bidirectional thyristor SS, the thyristor SS becomes conductive and the switching transistor Ql on one side is turned on.
A base current is supplied to b. Further, since a current is supplied to the collector of Qlb from the connection point J via the diode D1, Qlb becomes conductive, and the inverter circuit 5 is activated to start oscillation.

During this time, it goes without saying that a part of the load current is positively fed back by the transformer T2, and the switching transistors Q1a and Q1b are alternately turned on and off by their base drive circuits 5a and 5b, causing oscillation. sustain.

Immediately after startup, the fluorescent lamp F has not reached the dischargeable state, so the starting capacitor C connected between the choke coil CH and both filaments of the fluorescent lamp F is connected to the output terminal 6.
This means that a series resonant circuit with 2 is connected.
Since the Q of this resonance system is high, the load current is larger than that during normal lighting. Further, when the inverter circuit 5 starts oscillating and a load current flows, the chopper circuit 4 operates as described above to boost and smooth the output of the rectifier circuit 3.

Next, the chopper output control circuit 8 will be explained. This circuit 8 delays the ascending operation of the chopper circuit 4 until a predetermined time has elapsed after the inverter circuit 5 is activated, thereby reducing the output of the inverter circuit 5 during the predetermined period, thereby allowing the fluorescent lamp F to warm up. This prevents a so-called cold start, in which discharge begins before the power-up is complete. It is a soft start. Further, by detecting no load or load short circuit and turning off the transistor Qcp, the operation of the chopper iFI is stopped, and the DC output of the chopper circuit 4 and therefore the high frequency output of the inverter circuit 5 is reduced. That is, when the AC power supply 1 is turned on and the inverter circuit 5 is activated, a high frequency voltage is generated in the secondary winding W2b of the transformer T2. This voltage is converted into a DC output by the voltage doubler rectifier circuit 8a. When this DC output occurs, the circuit 8 operates, but after the power is turned on, the charge on the capacitor C83 is zero and the terminal voltage is also zero. For this reason, the Zener diode ZD8
1 and transistor Q82 are turned off, and transistor Q
81 is turned on, transistor Qcp is turned off, and the boost type chopper does not perform a boosting operation. Therefore, the chopper output and the output of the inverter circuit 5 are low. Next, the capacitor C83 is charged via the resistor R81 by the DC output of the voltage doubler rectifier circuit 8a, and when its terminal voltage exceeds the Zener voltage of the Zener diode ZD81, the Zener diode ZD81 is turned on, the transistor Q82 is turned on, and the transistor Q83 is turned on. Q81 turns off. As a result, the transistor Qcp starts turning on and off in accordance with the turning on and off of the transistor Q41. At this point, the step-up chopper circuit 4 operates for the first time, and boosts the input voltage of the inverter circuit 5 to the voltage during normal operation.

As a result, the output voltage of the inverter circuit 5 increases, and a voltage sufficiently higher than the discharge starting voltage is applied between both filaments of the fluorescent lamp F, so that the fluorescent lamp F starts discharging. After the discharge starts,
Since capacitor C2 is effectively bypassed by the lamp discharge path, the aforementioned resonance is shifted and the load current stabilizes;
It will be in a normal lighting state.

In addition, when there is no load, choke coil CH and capacitor C2
The load current increases due to series resonance with the

The voltage of the secondary winding W2a of the transformer T2 increases.

Therefore, the output voltage of the voltage doubler rectifier circuit 8a rises, and if this state continues for more than a set time, the terminal voltage of the capacitor C84, which is charged via the resistor R82, increases to the Zener diode ZD.
82 Zener voltage. This turns on Zener diode 2082 and transistor Q83,
Transistor Q82 turns off, and transistor Q8
1 turns on, turns off the transistor QCp, and stops the boosting operation of the chopper circuit 4. Therefore, the voltage supplied to the inverter circuit 5 is reduced.

When the load is short-circuited, the inverter circuit 5 becomes an L load, the load current decreases, and the voltage of the secondary winding W2b of the transformer T2 decreases. As a result, the output of the voltage doubler rectifier circuit 8a decreases, the Zener diode ZD83 is turned off, and the transistor Q
83 turns on. If the output voltage of the voltage doubler rectifier circuit 8a is equal to or higher than a predetermined value, the circuit 8a outputs the transistor Q84.
, the transistor Q83 is turned on via the resistor R83 and the Zener diode 2084, and thereafter, as in the case of no load, the transistor QCI) is turned off, the boosting operation of the chopper circuit 4 is stopped, and the input voltage of the inverter circuit 5 is reduce

FIG. 2 does not show the circuit configuration of a discharge lamp lighting device according to another embodiment of the present invention. The device shown in the same figure is different from the one shown in FIG.
A noise prevention circuit 2 is added, and the configurations of a boost type chopper circuit 4, an inverter circuit 5, and a chopper output control circuit 8 are modified.

In FIG. 2, parts common or corresponding to those of the device in FIG. 1 are indicated by the same reference symbols.

° In this chopper circuit 4, the high-frequency load current flowing through the trigger winding W1 of the transformer T1 exceeds a predetermined value for each cycle of this high-frequency load current, and the output voltage of the base drive winding W1b turns on the transistor Qcp. When the voltage exceeds the voltage, a small amount of base current flows through the transistor Qcp. As a result, the collector current of the transistor Qcp flows, which is transferred to the collector winding Wlc of the transformer T1.
and the transistor Qc via the base drive winding W1b.
positive feedback to the base of ρ. That is, the transistor QCI is immediately turned on by its collector-base positive feedback using the load current flowing through the trigger winding W1 of the transformer T1 as a trigger. By turning on, the inductor Lc
p is energized and electromagnetic energy is stored.

And the current of the inductor LCp, that is, the transistor,
When the collector current of the transformer Qcp increases and the transformer T1 becomes saturated, the output of the base drive winding W1b becomes zero and the transistor Qcp turns off, and the electromagnetic energy accumulated in the inductor LCp is transferred to the inductor LC11, the diode Qcp1, the inverter circuit 5, and the transistor Qcp. It is released through the rectifier circuit 3. Capacitor CCp smoothes the current supplied to inverter circuit 5. This output current is mainly determined by the on-duty of the transistor Qcp and is hardly dependent on the output voltage of the rectifier circuit 3. Moreover, in the phase where the output voltage of the rectifier circuit 3 is high, the transistor Qcp
Because the collector current rises quickly, the transformer T1
saturates quickly and the on-duty of the transistor Qcp becomes small. Conversely, in a phase where the output voltage of the rectifier circuit 3 is low, the saturation of the transformer T1 slows and the on-duty of the transistor Qcp becomes large. Therefore, the charging current to the smoothing capacitor Ccp is stabilized to some extent, and the smoothness of the DC output to the inverter circuit 5 is increased, and the AC power supply 1
The input power factor to the rectifier circuit 3 can be made high. Note that the diode Drs is used to allow current to flow through the base drive winding W1b of the transformer T1 while the transistor Qcp is off, and the impedance of the trigger winding W1 when viewed from the side is reduced and the transformer T1 is inserted. This is to eliminate the adverse effect on the load due to the above, and to reset the transformer T1 which has become saturated by turning on the transistor Qcp.

In the inverter circuit 5, T2 is a saturable feedback transformer having one negative winding W21 and two oppositely wound secondary windings W2a and W2b.

- The secondary winding W21 is inserted in series with the output terminal 6, detects the load current flowing therethrough, and generates corresponding secondary voltages having opposite phases to each other in the secondary windings W2a and W2b. The secondary winding W2a is connected to the input end of the base drive circuit 5a of the switching transistor Qla, and the output end of the base drive circuit 5a is connected to the base of the switching transistor Q1a.

Similarly, the secondary winding W2b is connected to the base of the switching transistor Q1b via the base drive circuit 5b.

The fluorescent lamp F is AC connected between the output terminal 6 of the inverter circuit 5 and the DC output terminal of the chopper circuit 4 via the choke coil CH and the trigger winding W1t of the saturable current transformer T1. . Further, in the transformer T3, two primary windings W31 and W32 are respectively inserted in series with both terminals of one filament of the fluorescent lamp F in the same phase, and the secondary windings W3a and W3b are each connected to a switching transistor. The secondary winding W of the transformer T2 is the input to the base drive circuits 5a and 5b of Q1a and Qlb.
2a and W2b are connected in opposite phases.

This device further includes a series circuit from the positive side DC output terminal of the chopper circuit 4 to the negative side DC output terminal of the chopper circuit 4 via the resistors R1, R2 and the capacitor C1 in order, and the resistors R1 and R2. A starting circuit for the inverter circuit 5 is formed by a relaxation oscillation circuit with a bidirectional thyristor SS connected in series from the connection point J to the base of the switching transistor Qlb. Note that the diode D1 connected in the forward direction between the connection point J and the collector of the switching transistor Q1b transfers the charging voltage of the capacitor C1 to the bidirectional thyristor SS after the inverter is started.
This is to prevent the inverter from malfunctioning by keeping the voltage below the breakover voltage and stopping the operation of the startup circuit.

When the AC layer WA1 is turned on in the device shown in FIG. 2, a rectified (pulsating current) output is generated from the rectifier circuit 3.

This pulsating output is smoothed by an L-shaped filter consisting of an inductor Lcp and a capacitor Cap of the chopper circuit 4, and a DC voltage approximately at the peak value of the AC power supply voltage is generated at the output end of the chopper circuit 4.

As a result, charge begins to accumulate in the capacitor C1 via the resistors R1 and R2. Then, when the potential at the connection point J exceeds the breakdown voltage of the bidirectional thyristor SS, the thyristor SS becomes conductive and supplies a base current to the switching transistor Q1b on one side. Further, since a current is supplied to the collector of Qlb from the connection point J via the diode D1, Qlb becomes conductive, and the inverter circuit 5 is activated to start oscillation.

Immediately after startup, the fluorescent lamp F has not reached the dischargeable state, so the starting capacitor C connected between the choke coil CH and both filaments of the fluorescent lamp F is connected to the output terminal 6.
A series resonant circuit with 2 is connected, and since the Q of this resonant system is high, the load current is larger than that during normal lighting. Further, when the inverter circuit 5 starts oscillating and a load current flows, the chopper circuit 4 operates as described above to boost and smooth the output of the rectifier circuit 3.

Resistor R3S, capacitor C831 constant voltage element (SCR,
SBS, etc.) Bss and the transistor Qss constitute a soft start circuit for preventing a so-called cold start in which the fluorescent lamp F starts discharging before the completion of forming up. That is, when the power is turned on, the transistor Qss is turned off and the emitter resistance of the transistor Q1b is set to a value R3 larger than that during normal lighting, and the voltage drop caused by this resistance is used to lower the output of the inverter circuit 5, thereby reducing the fluorescence. This prevents lamp F from starting cold. When the emitter resistance of the transistor Qlb becomes large, the amount of base drive of the transistor Qlb decreases, the saturation of the transformer T1 becomes faster, the storage time becomes shorter, and the excavation frequency increases, and the output of the inverter circuit 5 becomes lower than that due to the voltage drop of the emitter resistance. will further decline.

After the start of activation, the capacitor C3S is charged by the current flowing from the secondary winding W2b of the current transformer T2 via the diode Dss and the resistor R3S.

Then, when the terminal voltage exceeds the breakdown voltage of constant voltage element Bss, element 3ss is turned on, turning on transistor Qss. As a result, transistor Q1
The emitter resistance of b becomes the parallel resistance value of R3 and resistor R4 and decreases, and the output voltage of the inverter circuit 5 increases.

Therefore, a voltage sufficiently higher than the discharge starting voltage is applied between both filaments of the fluorescent lamp F, and the discharge starts. After the start of discharge, the capacitor C2 is substantially bypassed by the lamp discharge path, so the resonance described above is broken and the load current is stabilized, resulting in a normal lighting state.

During this time, it goes without saying that a part of the load current is positively fed back by the transformer T2, and the switching transistors Q1a and Qlb are connected to their base drive circuit 5.
Oscillation is maintained by being alternately turned on and off by a and 5b.

The transformer T3 is for limiting the current flowing when the load is short-circuited. That is, after the fluorescent lamp F starts discharging, the filament current flowing through the primary winding W31 of the transformer T3 is minute, and the filament current flowing through the primary winding W3 of the transformer T3 is small.
A and W3b generate a voltage that mainly corresponds to the lamp current flowing through the primary winding W32. The voltage generated in the secondary windings W3a, W3b acts in the direction of canceling the voltage generated in the secondary windings W2a, W2b of the transformer T2 in the base drive circuits 5a, 5b, and the transistors Q1a, Qlb
decreases the base current of Therefore, even if the load current attempts to increase due to a load short circuit, [・transistor Qla
When Q1b is turned on, the base current decreases faster, the oscillation frequency of the inverter circuit 5 increases, the impedance of the choke CH increases, and the increase in load current is limited. On the other hand, before the fluorescent lamp F starts discharging, a relatively large filament current flows through the choke coil CH and the capacitor C2.
3, the magnetic fluxes generated by these windings W31 and W32 cancel each other out, and the secondary windings W3a and W3b have outputs corresponding to the currents of Ficimen 1 and W32. Does not occur.

In the device shown in FIG. 3, the trigger winding Pi1wit of the transformer T1 is connected to the capacitor C2 for lamp starting, in contrast to the 8 positions shown in FIG.
The difference is that the transformer T3 is connected in series with the transformer T3. By connecting in this way, if the load current attempts to increase more than during normal operation due to a load short circuit, etc., the current flowing through the trigger winding W1t of the transformer T1 will increase, so the saturation time of the transformer T1 will be advanced, and the transistor Qcp will be Since the on-duty is reduced, the output of the chopper circuit 4 is reduced. That is, the function performed by the transformer T3 in the device of FIG. 2 can be performed by changing the connection position of the trigger winding W1.

Figure 4 is a circuit diagram in which only the soft start circuit of the boost chopper output control circuit shown in Figure 1 is connected to the step-up chopper circuit with the saturable current transformer shown in Figure 2.3. shows. After startup, transistor Q for a certain period of time
In order to prevent cp from starting oscillation, conduction is established between the collector and emitter of the auxiliary transistor Q81 connected between the base of the transistor QCI) and the negative side DC output terminal, so that the base drive current of the transistor Qcp is prevented from starting. This is done by letting it pass. The soft start operation is the same as in the case of FIG. In this case, the trigger winding is
It goes without saying that if the connections are made as shown in the figure, it is possible to reduce the current when the load is short-circuited.

As in the case of Fig. 4, Fig. 5 shows a step-up chopper circuit using a saturable current transformer, a soft start circuit on the back of the step-up chopper output control circuit shown in Fig. This is a circuit diagram in which a circuit for stopping the oscillation of a type chopper and a circuit for stopping the boosting function are connected. In this case, the inverter is either a series inverter or the like with no load and a large resonant current flows through it, or any inverter type may be used, but the output is a leakage transformer. When the output is a leakage transformer, the input end of the detection portion of the circuit is connected, for example, as shown in FIG. 6, from terminals d and e in the same figure to terminals d and e in FIG. 5.

Its operation is similar to that in FIG.

As described above, in the present invention, in a combination of a step-up chopper and an inverter-type discharge lamp lighting device, the load short-circuit current [2s and the no-load voltage V2G This is to reduce the power consumption, and to turn off the chopper transistor immediately after power is turned on to perform a soft start. That is, these are realized as described below.

■In the soft-start saturable current transformer type chopper, an auxiliary transistor is added between the base and collector of the chopper transistor, and a timer turns on this auxiliary transistor for a certain period of time after the power is turned on. In the auxiliary transistor chopper, a timer circuit is added to the existing auxiliary transistor.

■Load short-circuit current I2S reduction Saturable current transformer choppers use the preheating capacitor current (transformerless inverter) in parallel with the lamp, the preheating winding current (leakage transformer inverter), and the impedance current ( Trigger current is obtained from a leakage transformer type inverter. In the auxiliary transistor type chopper, a current transformer detects a drop in the lamp voltage VL, a change in frequency, or a current as in a saturable current transformer type chopper, and turns on the auxiliary transistor at all times.

■Lamp voltage VL for both saturable current transformer type and auxiliary transistor type inverters that reduce no-load voltage V20 (any inverter can be used)
, Filament current VF (with preheating capacitor, leakage transformer type inverter) ζ Detects the collector current or resonance current (series inverter), and turns on the auxiliary transistor if the value becomes high for a set time or longer.

■Reduce the no-load voltage by V20 when the lamp is not installed.The trigger current for the saturable current transformer is obtained from the preheating circuit.

Although a self-excited series inverter is used in this embodiment, any type of inverter may be used, such as a separately-excited type or one using an output transformer such as a constant current type inverter.

[Effects of the Invention] As described above, according to the present invention, by adding a simple small signal circuit, the soft start function 1b at the start of lighting and the function 1b at no load in a discharge lamp lighting device using a high frequency lighting method can be improved. It is possible to realize a power supply device equipped with an output reduction function and a current reduction function when a load is short-circuited. Also,
In this case, the greater the ratio of the output voltage of the step-up chopper circuit to the commercial power supply voltage, the greater the effect of reducing the no-load output and the current when the load is short-circuited.

[Brief explanation of drawings]

1 to 3 are circuit configuration diagrams of a discharge lamp lighting device according to an embodiment of the present invention. FIG. 4 is a circuit configuration diagram showing an application example of a soft start circuit. FIG. 6 is a circuit configuration diagram showing an application example of the output reduction circuit and the soft start circuit, and FIG. 6 is a circuit configuration diagram showing a connection example of a circuit that detects no-load from the leakage transformer output. 1: AC power supply, 3: Rectifier circuit, 4: Step-up chopper circuit, 5: Inverter circuit, 6: Output terminal, CCO: Smoothing capacitor, QCD: Chopper transistor, L cp: Inductor, Dcp, Drs: Diode, Q 1a, Q 1b switching transistor,
Q81. Q82. Q83. Q84: Transistor, ZD81. ZD82. ZD83:')xt
'jit-t', C83, C84, Css: Capacitor, R81, R82, Rss: Resistor, T1: Saturable current transformer, T3 Nidorance, Wlt: Trigger winding, WLC: Collector winding, %1b:
Base drive winding.

Claims (1)

[Scope of Claims] 1. In a power supply device comprising a DC power source, a step-up chopper that receives the DC power source as input, and an inverter that generates a high-frequency output from the DC output of the step-up chopper, the output state is as follows: A power supply device comprising: means for detecting the output of the chopper; and means for reducing the output of the chopper according to the output state. 2. The power supply device according to claim 1, wherein the output state is a no-load state when the power is turned on. 3. Claim 1, wherein the output state is a load short circuit.
Power supplies listed in section. 4. The power supply device according to claim 1, wherein the output state is no load.