JP3402966B2 - Power supply - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device which converts an AC power supply into a high frequency voltage by an inverter circuit and supplies it to a load.

[0002]

2. Description of the Related Art Conventionally, there has been a power supply device having a voltage resonance type single-stone inverter circuit as shown in FIG. In this power supply device, a DC power supply V _DC is switched by a transistor Q ₂ to supply a high frequency power supply to a load. To reduce the switching loss of the transistor Q _2, the control circuit 3, the voltage across V _Q2 of the transistor Q ₂ becomes to 0V, and a current flows to the flywheel diode D ₁₃ which are connected in anti-parallel to the transistor Q ₂ The transistor Q ₂ was turned on during the period (so-called zero volt switching).

By the way, since a delay time dt ₃ on the circuit occurs between the time when the voltage V _Q2 becomes 0 V and the time when the control circuit 3 turns on the transistor Q ₂ , a delay time dt ₃ on the circuit actually occurs. As shown, when the voltage V _Q2 across the transistor Q ₂ falls below a predetermined threshold value V ₁ (V ₁ > 0V), the control circuit 3 outputs an ON signal to the transistor Q ₂ after a delay time dt ₃ and the flywheel The transistor Q ₂ is turned on while the current I _D is flowing through the diode D ₁₃ . Here, immediately after the voltage V _Q2 between both ends becomes 0V, the transistor Q
_The delay time dt ₃ is set so that ₂ is turned on.

By the way, since the DC power supply V _DC has a substantially constant voltage, the peak value of the voltage V _Q2 across the transistor Q ₂ also becomes substantially constant. Therefore, the time from when the voltage V _Q2 between both ends falls below the threshold value V ₁ to when it becomes 0 V is substantially constant, so that if the delay time dt ₃ is designed as described above, stable oscillation operation can be performed. On the other hand, as shown in FIG. 13, instead of the DC power supply V _DC , the full-wave rectifier DB ₁
There is also one that uses a DC power supply that smoothes the rectified voltage of with a chopper circuit. In this power supply device, a chopper circuit is composed of a chopper inductor L ₂ , a transistor Q ₃ and a rechargeable DC power supply V _DC, and an inverter is composed of a transistor Q ₃ and a control circuit 3 for controlling ON / OFF of the transistor Q _3. The circuit is configured, and the transistor Q ₃ is shared by the chopper circuit and the inverter circuit. And
Similar to the power supply device described above, when the voltage V _Q3 across the transistor Q ₃ becomes 0 V, the control circuit 3 turns on the transistor Q ₃ after a certain delay time (Japanese Patent Laid-Open No. 4-271).
(See the official gazette).

[0005]

In the latter power supply device described above, the full-wave rectification circuit DB performs full-wave rectification of the AC power supply AC, and the chopper circuit smooths the rectified voltage of the full-wave rectification circuit DB. As shown in FIG. 14A, in the peak portion of the AC power supply AC, the peak value of the voltage V _Q3 across the transistor Q ₃ is larger than in the valley portion of the AC power supply AC. Therefore, the energy stored in the chopper inductor L ₂ changes according to the peak value of the voltage V _Q3 across the voltage, and the resonance condition of the resonance circuit system also changes.

[0006] FIG. 14 (b) (c), the AC power supply voltage across V _Q3 of the transistor Q ₃ in the crest and valleys of the AC, on signal of the transistor Q _3, a current I _Q3 flowing through the transistor Q _3, a flywheel Current I flowing through diode D _13
D is shown respectively. In the peak portion of the AC power supply AC, the voltage V _Q3 across the transistor Q ₃ is higher than in the valley portion of the AC power supply AC.
, The time t ₁ from when the voltage V _Q3 across the transistor Q ₃ falls below the predetermined threshold V ₁ to when it reaches 0 V is t _{2 at} the valley of the AC power supply AC.
Will be shorter than.

Therefore, when the delay time dt ₄ from when the voltage V _Q3 across the transistor Q ₃ falls below the predetermined threshold value V ₁ until the control circuit 3 turns on the transistor Q ₃ is constant, the AC power supply AC In the mountain portion, as shown in FIG. 14B, the control circuit 3 turns on the transistor Q ₃ in a period in which a current flows through the flywheel diode D ₁₃ after the voltage V _Q3 across the transistor Q ₃ becomes 0V. Although it has to (t ₁ <dt _4), in the valleys alternating current power source AC, 14
As shown in (c), the voltage V _Q3 across the transistor Q ₃
There before becoming 0V, to turn on the transistor _{Q 3 (t 2> dt 4} ), rush current flows through the transistor Q _3, there is a problem that stress is applied to the transistor Q _3.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a power supply device capable of performing stable oscillation operation without being affected by the voltage ripple of the input voltage. To provide.

[0009]

In order to achieve the above object, a rectifier circuit for rectifying an AC power supply, a chopper inductor connected between output terminals of the rectifier circuit, and a switching element are provided. A chopper circuit composed of a series circuit, a flywheel diode connected in anti-parallel to a switching element, a load connected in parallel to the switching element, and a control circuit for turning on / off the switching element at a high frequency are provided. When the voltage across the switching element falls below a specified threshold value, the control circuit turns on the switching element while the current flows through the flywheel diode.
The voltage across the switching element drops below the threshold.
After turning, the control circuit turns on the switching element.
The delay time at the peak of the voltage across the switching element.
Since it is changed according to the value, it is possible to prevent a rush current from being generated when the switching element is turned on.

According to the second aspect of the invention, the AC power supply is rectified.
A rectifier circuit and a choke connected between the output terminals of the rectifier circuit.
It consists of a series circuit of a power inductor and a switching element.
Connected in reverse parallel to the chopper circuit and switching element
Flywheel diode and switching element connected in parallel
The load to be continued and the switching element are turned on / off at high frequency.
A switching element and a control circuit.
The inverter circuit is composed of the
If the end voltage falls below a specified threshold, the flywheel diode will
While the current is flowing through the
When the child is turned on, the threshold value is changed according to the peak value of the voltage across the switching element. According to the invention of claim 3 , the threshold value is increased when the peak value of the voltage across the switching element is larger than a predetermined value. to together, when the peak value of the voltage across the switching element is smaller than a predetermined value, since the lower threshold, the on time of the rush current of the switching element can be prevented from occurring.

According to the invention of claim 4 , the AC power supply is rectified.
A rectifier circuit and a choke connected between the output terminals of the rectifier circuit.
It consists of a series circuit of a power inductor and a switching element.
Connected in reverse parallel to the chopper circuit and switching element
Flywheel diode and switching element connected in parallel
The load to be continued and the switching element are turned on / off at high frequency.
A switching element and a control circuit.
The inverter circuit is composed of the
If the end voltage falls below a specified threshold, the flywheel diode will
While the current is flowing through the
When the child is turned on, the strength of voltage resonance of the inverter circuit is changed according to the peak value of the voltage across the switching element. In the invention of claim 5 , the strength of voltage resonance is changed by frequency modulation control. According to the invention of claim 6 , when the peak value of the voltage across the switching element is larger than a predetermined value, the switching frequency is controlled to be high, and when the peak value of the voltage across the switching element is smaller than the predetermined value. Since the switching frequency is controlled to be low, the ripple of the voltage across the switching element can be reduced.

[0012]

[0013]

According to the invention of claim 7 , since the load is composed of the lighting load, the lighting load can be stably turned on.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings. (Embodiment 1) FIG. 1 shows a circuit diagram of a discharge lamp lighting device using the power supply device of this embodiment. The full-wave rectifier circuit DB is composed of four diodes D _{1 to} D ₄ that are bridge-connected, an AC power supply AC is connected between the input terminals, and a chopper inductor L ₁ and a resonance inductor between the output terminals. A series circuit composed of L ₂ and the smoothing capacitor C ₁ is connected. Between the connection point of the inductors L ₁ and L _{2 and} the connection point of the smoothing capacitor C ₁ and the full-wave rectification circuit DB, a resonance capacitor C ₂ and a MOS field effect transistor (hereinafter, referred to as a switching element) Q ₁ (abbreviated as FET) is connected in parallel. In addition, FETQ ₁
A series circuit including a ballast inductor L ₃ , a load 2 and a direct current cut capacitor C ₄ is connected in parallel with.
A chopper circuit is composed of the chopper inductor L ₁ , the FET Q ₁ and the smoothing capacitor C ₁ . Further, the control circuit 3 is to control the on and off FETs Q _1, inverter circuit is constituted by FETs Q ₁ and a control circuit 3 which, FETs Q ₁ in the chopper circuit and an inverter circuit
Are shared. The parasitic diode (not shown) of the FET Q ₁ functions as a flywheel diode.

The load 2 is composed of a discharge lamp La such as a fluorescent lamp having a filament, and a preheating capacitor C ₃ connected between the ends of both filaments of the discharge lamp La on the non-power source side. Power side end of both filaments of the discharge lamp La, the inductor L ₁ through the stable dexterity inductor L _3,
The other ends of the filaments on the power source side are connected to the connection point of L _{2 and} the connection point of the FET Q ₁ and the full-wave rectifier circuit DB via the DC cutting capacitor C ₄ .

The operation of this circuit will be described. This time
The road is FETQ₁And resonance capacitor C₂By the action of
Basically, it operates in four operation modes. FETQ₁But
When turned on, the resonance capacitor C₂Both ends of are short-circuited
Does not function, smoothing capacitor C₁From resonance for inductor
L₂Current flows to the capacitor C_FourReleased from
Electric lamp La (pre-ripening capacitor C₃) And ballast inductor
L₃Current flows in the series circuit with
₂And ballast inductor L ₃And magnetic energy is stored in
Be done. In addition, the full-wave rectifier circuit DB to the inductor for the chopper
L₁Current flows into the inductor, and the inductor for the chopper L₁Also porcelain
Air energy is stored. The output voltage of full-wave rectifier DB is
Since it is approximately equal to the absolute value of the voltage of the AC power supply AC, the chopper
Inductor L₁The current flowing in the
The value is proportional to the absolute value.

Immediately after the FET Q ₁ is turned off, the magnetic energy stored in the resonance inductor L ₂ and the ballast inductor L ₃ is released, so that the resonance inductor L ₂ and the ballast inductor L ₃ are discharged. FE to ₃
Current continues to flow in the same direction as when TQ ₁ is on, and the resonance capacitor C ₂ is charged. Therefore, the voltage across the resonance capacitor C ₂ (the drain-source voltage of the FET Q ₁ ) rises. Further, since the magnetic energy of the chopper inductor L ₁ is released, the current continues to flow in the chopper inductor L ₁ in the same direction as when the FET Q ₁ is turned on. Here, the magnitude of the current flowing through the chopper inductor L ₁ is proportional to the absolute value of the magnetic energy, i.e. the AC power source AC voltage stored in the chopper inductor L _1.

After that, the resonance inductor L₂And for ballast
Inductor L₃And the magnetic energy with
And capacitor C for resonance₂Starts to discharge. At this time
Discharge current of the resonance inductor L₂For smoothing through
Densa C₁It becomes the charging current to. At the same time, stable
Inductor L₃And discharge lamp La (pre-ripening capacitor C
₃) Through a series circuit with a capacitor C_FourThe charging current is
Flowing. Also, the inductor L for the chopper₁Is magnetic energy
Chopper inductor L ₁Flow
The generated current is the resonance inductor L₂Through smoothing conde
Sensor C₁It becomes the charging current to.

When the resonance capacitor C ₂ is discharged, the drain voltage of the FET Q ₁ becomes lower than the source voltage due to the magnetic energy of the resonance inductor L ₂ and the ballast inductor L _3, and the parasitic diode of the FET Q ₁ becomes conductive. To do. As a result, the resonance inductor L ₂ continues to flow the charging current to the smoothing capacitor C _{1 in the} same direction as when the resonance capacitor C ₂ starts to discharge, and the inductor for the ballast inductor
BR> data L ₃ continues to flow the charging current to the capacitor C ₄ .
Also, the current flowing through the chopper inductor L ₁ continues to charge the smoothing capacitor C ₁ and the capacitor C ₄ as when the resonance capacitor C ₂ is discharged. here,
The inductance of the chopper inductor L _1, the current flowing through the chopper inductor L ₁ is also that the idle period occurs.

By the way, the control circuit 3 includes a pair of resistors.
R₁, R₂The series circuit of FETQ₁Be connected in parallel
FETQ₁Voltage between both ends (voltage between drain and source)
Voltage) and detects resistance R₂Connected in parallel to
Capacitor C_FiveFETQ ₁Proportional to the voltage across
Voltage is integrated. Capacitor C_FiveThe voltage b across
Circuit IC₁After the waveform is shaped by
₆And resistance R₇Through the differentiating circuit, and the inverting circuit I
C₂The waveform is shaped with. This inversion circuit IC₂Output signal of
Is a general-purpose timer integrated circuit (eg NEC μ
PC1555) IC _FourIs a monostable multi
It is input as a trigger signal to the vibrator. This simple price
The constant multivibrator has a resistance R_FourAnd capacitor C₈When
Determines the time constant. It also prevents malfunctions immediately after the power is turned on.
Capacitor C for stopping₇Equipped with. On the other hand, immediately after turning on the power
FETQ₁Another control power supply (not shown)
V_DDResistors connected across (obtained from AC power supply AC)
R₆And capacitor C₉And a series circuit with a resistor R₆And con
Densa C₉Inversion circuit IC connected to the connection point with₃And
Prepare Also, the diode D₇, D₈Is a half-wave rectifier circuit 4
And the output of the half-wave rectifier circuit 4 is a resistor R₈Through
Anti-R_FourAnd capacitor C_FiveIt is connected to the connection point with. Above
Monostable multivibrator and inverting circuit IC₃Out
Each force is a diode D that constitutes a wired OR.
_Five, D₆And resistance R₃Through FETQ ₁At the gate of
Connected. Also, the diode D_Five, D₆On the cathode of
Is a pull-down resistor R_FiveIs also connected.

Next, the operation of the control circuit 3 will be described with reference to FIG.
A description will be given with reference to (a) and (b). FIG. 2A shows the waveform of each part in the peak part of the AC power supply AC, and FIG. 2B shows the waveform of each part in the valley part of the AC power supply AC.
Further, a to e and g to j in FIGS. 2A and 2B are respectively shown in FIG.
Of the voltage waveforms a to e and g to j, and I _Q1 and I _{La respectively} represent current waveforms of currents flowing through the FET _{Q 1} and the discharge lamp La (the arrow direction in the drawing is positive). This control circuit 3
When the voltage across the FET Q ₁ divided by the resistors R ₁ and R ₂ becomes approximately 0 V, a drive signal is output to turn on the FET Q ₁ for a certain period of time, and so-called zero volt switching is performed.

First, when the power is turned on, the input k of the inverting circuit IC ₃ is at a low level and the output l thereof is at a high level, so that the gate of the FET Q ₁ is connected via the diode D ₆ and the resistor R _3. The high-level signal j is input to the FET Q ₁ and the FET Q ₁ is turned on. After that, when the capacitor C ₉ is charged from the control power supply V _DD via the resistor R ₆ , the input k of the inverting circuit IC ₃ reaches the threshold value after a certain period of time,
The output l of the inverting circuit IC ₃ changes from the high level to the low level, and the FET Q ₁ is turned off.

The circuit starts operating under the control at the time of startup as described above. That is, [a in FIG. 2 (a) (b)] to resonant inductor L _2, the voltage resonance switch composed of resonant capacitor C ₂ and FETs Q _1, the drain voltage a of FETs Q ₁ is increased. After that, the drain voltage a of the FET Q ₁ is substantially 0 due to the resonance operation of the series resonance circuit by the resonance inductor L ₂ and the resonance capacitor C _2.
When it becomes V, the voltage b divided by the resistors R ₁ and R ₂
Also becomes approximately 0 V [b in FIGS. 2 (a) and 2 (b)]. Here, since the capacitor C ₅ is connected to the input terminal of the inverting circuit IC ₁ , the change in the drain voltage a of the FET Q ₁ is delayed, and malfunction due to chattering is prevented. The input b of the inverting circuit IC ₁ is a predetermined threshold value Vth (for example, the inverting circuit I
The output c of the inverting circuit IC ₁ becomes the H level when the voltage becomes equal to or lower than the voltage of the power source voltage of C ₁ ) (FIG. 2 (a)).
C in (b)]. When the output c of the inverting circuit IC ₁ rises, the input d of the inverting circuit IC ₂ goes to the H level for a short time through the differentiating circuit composed of the capacitor C ₆ and the resistor R ₇ (see FIGS. 2A and 2B). d], the inversion circuit IC ₂ generates an output e which becomes L level for a short time [FIG.
(E) of (a) and (b)].

Inversion circuit IC thus obtained₂of
The output e triggers the monostable multivibrator,
Resistance R that determines the time constant_FourAnd capacitor C₈Connection point with
The potential g rises [g in FIGS. 2 (a) and 2 (b)]. For timer
Integrated circuit IC_FourThen the resistance R _FourAnd capacitor C₈Contact with
The potential g at the continuation point is the control voltage V_DDReaching about two-thirds of
Capacitor C₈To discharge rapidly. Where conden
SA C₈Integrated circuit IC for timer while charging_FourOutput h of
High level [h in FIGS. 2 (a) and 2 (b)], dio
Mode D_FiveAnd resistance R₃Through FETQ₁At the gate of
A level j signal j is applied [see FIGS. 2 (a) and 2 (b).
j], FETQ₁Is turned on. In other words, FET
Q₁Has a drain voltage a of about 0 V and a voltage b of a predetermined value.
When it falls below the threshold value Vth, FETQ₁For a certain time (potential g
Control voltage V_DDON until it reaches approximately two-thirds of
become.

On the other hand, the potential f of the terminal of the timer integrated circuit IC ₄ to which the capacitor C ₇ is connected is a time constant determined by the internal resistance of the timer integrated circuit IC ₄ and the capacitor C ₇ . After the power is turned on, the voltage gradually rises, and when the potential f is below a predetermined value, the timer integrated circuit IC
The output h of ₄ is kept low. Therefore, FE
The on-time of TQ ₁ is set by the resistor R ₄ and the capacitor C _8, and the off-time is determined by the time until the drain voltage a of the FET Q ₁ returns to 0V. That is, FET
The off time will be adjusted depending on the state of the circuit including Q ₁ .

Resonant inductor L₂And resonance capacitor C
₂By the LC resonance operation of FETQ ₁Drain voltage a
When the voltage drops to almost 0V, the resistance R₁, R₂By
The divided voltage b also drops to approximately 0V in synchronization with the voltage a.
To do. Then, when the voltage b falls below a predetermined threshold value Vth,
As described above, the control circuit 3 is FETQ₁Turn on. Toko
By the way, integrated circuit IC for timer_Four, Resistance R₃And FETQ
₁The voltage b falls below the threshold Vth due to factors such as the input capacitance of the
After detecting the turning, FETQ₁Until is turned on
In the meantime, the delay time (dt in FIGS. 2A and 2B)₁Dt₂)But
FETQ₁Current flows through the parasitic diode of
FETQ₁Turn on the zero volt switch
Delay time dt₁Dt₂Consider
The threshold Vth to the control voltage V_DDIs set to about half
It

[0028] Here, half-wave rectifier circuit 4 composed of the diode D _7, D ₈ are half-wave rectifying an alternating current power source AC, a resistor R ₄ and the capacitor C ₈ to its output through a resistor R ₈ Connected to the connection point. And the half-wave rectifier circuit 4
By charging the capacitor C ₈ with the output of, the time constant of the time constant circuit composed of the resistor R ₄ and the capacitor C ₈ , that is, the on-time T ₁ , T ₂ of the FET Q ₁ ,
It is changed according to the peaks and valleys of the AC power supply AC.

In the peak portion of the AC power supply AC, the charging current for charging the capacitor C ₈ from the half-wave rectification circuit 4 via the resistor R ₈ increases as compared with the valley portion of the AC power supply AC, so that the capacitor C ₈ The time T ₁ for the potential g to rise to approximately two-thirds of the control voltage V _DD becomes shorter. This time T ₁ determines the period during which the output h of the timer integrated circuit IC ₄ is at a high level, that is, the ON time of the FET Q ₁ ,
The on-time of Q ₁ becomes shorter and the switching frequency becomes higher.

On the other hand, in the valley of the AC power supply AC, there is almost no charging current for charging the capacitor C ₈ from the half-wave rectifier circuit 4 via the resistor R ₈ , and the capacitor C ₈ and the resistor R ₄
Potential by the time constant of the time constant circuit consisting of g is determined the time T ₂ which rises to 2 of approximately 3 minutes of the control voltage V _DD, the time T ₂ are longer than the time T ₁ at the peak portion of the AC power source AC. Therefore, the ON time of FET Q ₁ becomes long,
The switching frequency is low.

Thus, the ON time of the FET Q ₁ is set by the time constant circuit consisting of the resistor R ₄ and the capacitor C _8, and the output of the half-wave rectifier circuit 4 charges the capacitor C ₈ via the resistor R _8. Therefore, the charging current of the capacitor C ₈ changes according to the voltage of the AC power supply AC, and the FET
The ON time of Q ₁ changes according to the voltage of the AC power supply AC.

[0032] Thus, even off-time of FETs Q ₁ from the change in the energy of the chopper circuit to be accumulated during the on-FETs Q ₁ can be adjusted, crests of the AC power source AC, the ripple of the peak value of the drain voltage a in the valleys is reduced Therefore, the FET Q ₁ can be reliably turned on during the period when current is flowing through the flywheel diode, and stable oscillation operation can be performed. Further, since the ripple of the peak value of the drain voltage a is reduced, the peak value of the drain voltage a in the peak portion of the AC power supply AC is lowered, the withstand voltage of the FET Q ₁ can be suppressed, and the reliability of the FET Q ₁ is improved. You can Further, the cost can be reduced by using the FET Q ₁ having a small rated capacity.

The inverting circuit IC ₃ and the timer integrated circuit I
If the C ₄ can not supply the current required to drive the FETs Q _1, it may be added to the drive circuit for driving the FETs Q _1. Further, the voltage f at the control terminal of the timer integrated circuit IC ₄ is set to a predetermined time constant by the integrating circuit composed of the internal resistance and the capacitor C ₇ , and after a predetermined time elapses, it changes from low level to high level. The logic inverts to the level, but the voltage f is at the low level,
The output of the timer integrated circuit IC ₄ is fixed at a low level.

In the present embodiment, the half-end rectification circuit 4 composed of the diodes D ₇ and D ₈ is connected to the input side of the full-wave rectification circuit DB, but it may be connected to the output side of the full-wave rectification circuit DB. good. (Embodiment 2) A circuit diagram of a discharge lamp lighting device using the power supply device of this embodiment is shown in FIG.

In the present embodiment, in the discharge lamp lighting device of the first embodiment, a full-wave rectifier DB ₁ is used instead of the full-wave rectifier circuit composed of a diode, and a chopper inductor L ₁ and a resonance capacitor C ₂ are used. In between, inductor L ₁
A diode D ₉ for a reverse current element is connected in a direction in which a current flows from C to C ₂ , a capacitor C ₁₁ is connected between the output terminals of the full-wave rectifier DB ₁ , and a connection point between the inductor L ₁ and the diode D ₉ and FETQ. _A diode D ₁₀ is connected in antiparallel between ₁ and the full-wave rectifier DB ₁ . here,
The capacitor C ₁₁ and the diode D ₁₀ remove the oscillating voltage generated in the chopper inductor L ₁ .

Further, the control circuit 3 includes a resistor R₉~ R₁₁And
Indexer C_TenAnd control integrated circuit IC _FiveConsists of and
It Resistance R₉One end of is a full-wave rectifier DB₁On the high potential side of
Connected to the force end, resistance R₉The other end of the resistor R_TenTouch one end of
Continued resistance R_TenThe other end of is connected to ground. resistance
R₁₁One end of the resonance inductor L₂And smoothing conden
SA C₁It is connected to the connection point with₁₁The other end of
Densa C_TenConnected to one end of the capacitor C_TenThe other end of
Connected to ground. And the resistance R₉, R_TenConnection
Point and resistance R₁₁And capacitor C_TenIs the control point
Product circuit IC_FiveAre connected to the input terminals of.

FIG. 4 shows the voltage waveform of each part. A to C in the figure
Shows the voltage waveforms at points A to C in FIG. The voltage at point A is a voltage obtained by dividing the voltage across smoothing capacitor C ₁ ,
The voltage at point B is the resistance of the voltage of the full-wave rectifier DB ₁ R _9, R ₁₀
The voltage is divided by. Then, the control integrated circuit IC ₅
A voltage C, which is a superposition of the voltage A and the voltage B, is input to the input terminal. From this voltage C, the voltage across the FET Q ₁ (drain
It is detected that the (source voltage) becomes 0V.

When the voltage C falls below a predetermined threshold value, the control circuit 3 turns on the FET Q ₁ after a predetermined delay time. Since the voltage B becomes large in the mountain part of the AC power supply AC,
The voltage C also increases, and the voltage B decreases in the valley portion of the AC power supply AC, so the voltage C also decreases. Therefore, since the time when the voltage C falls below the threshold value changes depending on the peaks and valleys of the AC power supply AC, even if the voltage across the FET Q ₁ has ripples due to the peaks and valleys of the AC power supply AC. , F
Voltage across 0V next ETQ _1, the period during which the current flows through the parasitic diode of FETs Q _1, can be turned on reliably FETs Q _1.

In this embodiment, the voltage C is changed according to the peaks and troughs of the AC power supply AC, but the threshold value may be changed according to the peaks and troughs of the AC power supply AC. That is, the threshold value is increased in the mountain portion of the AC power supply AC, and the FETQ
Advance the time to detect when ₁ becomes 0V, and use the AC power supply AC
And the lower the threshold value in the valleys of the power supply voltage, FETs Q ₁ is 0
You may delay the time of detecting becoming V. Also, F
From the voltage across the ETQ ₁ falls below the predetermined threshold value, the delay time until the control circuit 3 turns on the FETs Q _1, AC short in supply AC of ridges, may be long in the valleys of the AC power source AC Similarly, it is possible voltage across the FETs Q ₁ is 0V and the period during which the current flows through the flywheel diode consisting of the parasitic diode of FETs Q _1, to reliably turn on the FETs Q _1. (Embodiment 3) In this embodiment, the control circuit 3 of Embodiment 1 or 2 is applied to a voltage resonance type single-stone inverter circuit which also serves as a chopper and constitutes a step-up / down chopper circuit.

As shown in FIG. 5, the discharge lamp lighting device using the power supply device of this embodiment has an AC power supply AC, a full-wave rectifier DB ₁ for full-wave rectifying the AC power supply AC, and a full-wave rectifier D.
A series circuit including an FET Q ₁ and a chopper inductor L ₁ connected between the output terminals of B ₁ , a diode D ₁₁ and a smoothing capacitor C ₁ connected in parallel with the chopper inductor L _1, and a parallel connection to the FET Q _1. A series circuit of the ballast inductor L ₃ , the DC cut capacitor C _4, and the load 2, the resonance capacitor C ₂ connected in parallel to the FET Q ₁ , and one end of the connection point between the FET Q ₁ and the full-wave rectifier DB _1. Resonance inductor L connected to the other end of the diode D ₁₁ and smoothing capacitor C _1
2, and a control circuit 3 for controlling on / off of the FET Q ₁ based on the voltage of the AC power supply AC and the smoothing capacitor C ₁ . Here, the diode D ₁₁ is connected in a direction in which a current flows from the inductor L ₁ to the capacitor C ₁ via the diode D ₁₁ .

By the way, the chopper inductor L _1, diode D _11, FETs Q ₁ and is constituted buck-boost chopper circuit from the capacitor C _1, the FETs Q ₁ is turned on, the inductor via the FETs Q ₁ from the full-wave rectifier DB ₁ L current flows in _1, energy is stored in inductor L _1. Next, when the FETs Q ₁ is turned off, the energy accumulated in the inductor L ₁ is, the inductor L ₁ → diode D ₁₁ → to release the path of the capacitor C ₁ → inductor L _1, charges the smoothing capacitor C _1.

The control circuit 3, as in Embodiment 1 or 2, based on the capacitor C ₁ and the AC power source AC voltage smoothing, when the voltage across V _Q1 of FETs Q ₁ is detected to become 0V, FETs Q ₁ The FET Q ₁ can be turned on while the current is flowing in the parasitic diode, and a stable oscillation operation can be performed without generating a rush current.

As described above, in the case of the voltage resonance single-stone inverter that also serves as a chopper, by providing the control circuit of the first or second embodiment, stable oscillation operation can be performed. The load 2 and the control circuit 3 have the same configurations as those of the first or second embodiment, and thus the description thereof will be omitted. (Embodiment 4) A discharge lamp lighting device using the power supply device of this embodiment is, as shown in FIG. 6, between a full-wave rectifier DB ₁ for full-wave rectifying an AC power supply AC and an output terminal of the full-wave rectifier DB _1. Chopper inductor L ₁ and FET Q connected to
₁ of a series circuit, a capacitor C ₂ connected between the drain and source of the FETs Q _1, stable dexterity inductor L ₃ and the load 2 and the smoothing series circuit of a capacitor C ₁ connected between the drain and source of the FETs Q ₁ And a control circuit 3 for controlling ON / OFF of the FET Q ₁ based on the voltage of the smoothing capacitor C ₁ and the AC power supply AC. Also,
The load 2 is composed of a discharge lamp La such as a fluorescent lamp having a filament, and a parallel circuit of a preheating capacitor C ₃ and a resistor R ₁₂ connected between the non-power source side ends of the filament of the discharge lamp La. One ends of both filaments of the discharge lamp La on the power supply side are connected to the resonance inductor L ₂ , and the other ends are connected to the smoothing capacitor C ₁ .

[0044] In the mountain part of the output voltage of the full-wave rectifier DB _1, the FETs Q ₁ is turned on, the path of the full-wave rectifier DB ₁ → inductor L ₁ → FETQ ₁ → the full-wave rectifier DB _1,
A current flows through the inductor L _1, the energy is accumulated in inductor L _1. Further, a lamp current flows from the smoothing capacitor C ₁ to the discharge lamp La in the route of the discharge lamp La → the inductor L ₃ → FETQ ₁ → the smoothing capacitor C ₁ .
When FETs Q ₁ is turned off, the inductor L _1, the energy stored in L ₃ when the ON FETs Q ₁ is released, the capacitor C ₂ is charged. When the release of the energy of the inductors L ₁ and L ₃ is completed, the capacitor C ₂ discharges along the path of the capacitor C ₂ → the inductor L ₃ → the discharge lamp La → the capacitor C ₁ → the capacitor C _{2 and} the capacitor C ₂ is discharged.
₁ is charged. Since the capacitance of the capacitor C ₁ is sufficiently larger than that of the capacitor C ₂ , the voltage of the capacitor C ₁ is smoothed.

On the other hand, at the valley of the output voltage of the full-wave rectifier DB ₁ , the smoothing capacitor C ₁ is the capacitor C ₁ → discharge lamp La → inductor L ₃ → capacitor C ₂ → capacitor C
_The discharge is performed through the path ₁ and the lamp current flows through the discharge lamp La. Therefore, since the lamp current flows through the discharge lamp La even in the valley portion of the output voltage of the full-wave rectifier DB ₁ , there is no pause period of the lamp current and the luminous efficiency of the discharge lamp La is high.

By the way, in the discharge lamp lighting device of the present embodiment, not only the voltage across the FET Q ₁ but also the lamp current of the discharge lamp La has ripples due to the power supply voltage of the AC power supply AC, but the control circuit 3 Controls ON / OFF of the FET Q ₁ based on the voltage of the smoothing capacitor C ₁ and the AC power supply AC as in the first or second embodiment.
A stable oscillation operation can be performed, and the current ripple of the lamp current of the discharge lamp La can be reduced.

Further, in this embodiment, since the smoothing capacitor C ₁ and the full-wave rectifier DB ₁ are not directly connected,
The rush current does not flow into the smoothing capacitor C ₁ when the power is turned on. The configuration of the control circuit 3 is the same as that of the first embodiment.
Or, since it is the same as that of 2, the description thereof is omitted. (Embodiment 5) As shown in FIG. 7, a discharge lamp lighting device using the power supply device of the present embodiment has a full-wave rectifier DB ₁ for full-wave rectifying an AC power supply AC and an output terminal of the full-wave rectifier DB _1. Chopper inductor L ₁ and FET Q ₁ connected to
And a series circuit of an inductor L ₂ and a smoothing capacitor C _1, a series circuit of a ballast inductor L ₃ , a DC cut capacitor C ₄ and a load 2, and a capacitor C ₂ are the drain of the FET Q ₁ . -Connected in parallel between sources. The load 2 is a discharge lamp La such as a fluorescent lamp having both filaments, and a preheating capacitor C connected between the non-power source side ends of both filaments of the discharge lamp La.
Is composed of _three Prefecture, power side end of both filaments of the discharge lamp La is connected to the capacitor C ₄ DC blocking, the other end thereof is connected to the smoothing capacitor C _1.

In the present embodiment, since the constants of the chopper inductor L ₁ and the resonance inductor L ₂ which affect the resonance are made substantially equal (L ₁ ≈L ₂ ), the resonance voltage of the FET Q ₁ determined by the resonance condition. Can be reduced due to the input voltage. Therefore, since the voltage ripple of the voltage across the FET Q ₁ can be reduced, the control is performed during the period when the current flows through the parasitic diode of the FET Q ₁ after the voltage across the FET Q ₁ becomes 0 V, as in the first embodiment. It is possible to set the threshold voltage of both ends and the delay time until the FET Q ₁ is turned on so that the circuit 3 turns on the FET Q ₁ , and stable oscillation operation can be performed.

The configuration of the control circuit 3 is the same as that of the first embodiment.
Since it is the same as that of 2, the description thereof is omitted. (Embodiment 6) A discharge light spot using the power supply device of this embodiment
As shown in FIG. 8, the lighting device uses a full-wave commercial AC power supply AC.
Full-wave rectifier DB for rectification₁And full-wave rectifier DB₁Output
Inductor L connected between terminals₁And diode D₁₂When
FETQ₁Series circuit and diode D₁₂Connected in parallel with
First resonant capacitor C₁₂And inductor L₁Over
And capacitor C₁₂Connection point and FETQ₁And full-wave rectifier
DB₁A second resonant capacitor connected between the
SA C₁₃And FETQ₁Connected between the drain and source of
Inductor L₂And smoothing capacitor C₁Series circuit of
And FETQ ₁Connected between the drain and source of
Ballast inductor L₃And DC cut capacitor C
_FourAnd a series circuit of the discharge lamp La and both filaments of the discharge lamp La
Capacitor C for preheating connected between the non-power supply side ends₃
And FETQ₁Control circuit 3 that turns on and off
To be done.

The operation of this discharge lamp lighting device is the same as in the first embodiment.
The operation of the discharge lamp lighting device is almost the same as that of FET Q ₁
The charging and discharging operations of the first and second resonant capacitors when the switch is off are different. At the peak of the output voltage of the full-wave rectifier DB ₁ , the diode D ₁₂ is turned on, so that the second resonant capacitor C ₁₃ mainly performs the charging / discharging operation. As shown in FIG. 9A, when the capacitor C ₁₃ is charged, a current flows from the inductors L ₁ and L ₃ to the capacitor C ₁₃ (arrow A in the figure) to charge the capacitor C ₁₃ . When the capacitor C ₁₃ is discharged, a current flows from the capacitor C ₁₃ to the inductors L ₂ and L ₃ via the diode D ₁₂ (indicated by arrow B in the figure).

On the other hand, full-wave rectifier DB₁Valley of the output voltage of
Then, the first and second resonant capacitors C₁₂, C₁₃Midpoint
The voltage of the first resonance capacitor C is about 0V.₁₂But
Charging / discharging operation is mainly performed. As shown in Fig. 9 (b)
And the first resonance capacitor C₁₂When charging the inductor
L₂, L₃Releases energy and inductor L₂, L
₃To the first resonant capacitor C₁₂Current flows through (in the figure,
Arrow C), the first resonance capacitor C₁₂To charge. Well
And the first resonance capacitor C₁₂When discharging, the first resonance
Capacitor C₁₂Is the inductor L₃Discharge through (Fig.
Middle, arrow d).

Therefore, the first and second resonant capacitors
SA C₁₂, C₁₃By optimally designing the capacitance value of
, Full-wave rectifier DB₁The peak and valley of the output voltage of
ETQ ₁To reduce the ripple generated in the voltage across
You can Therefore, full-wave rectifier DB₁Output voltage peak
At FETQ₁To reduce the voltage applied to the
FETQ₁Can improve the reliability of
It (Embodiment 7) In this embodiment, as shown in FIG.
In the power supply device of the first embodiment, the discharge lamp La and the condenser
SA C_FourConnection point and inductor L₂And capacitor C₁Contact
Between the continuation point and the capacitor C_FourCapacitor C from the side₁~ side
In the direction of the current flowing through the diode D₁₃Have inserted
It

In this power supply device, the voltage across the capacitor C ₄ is clamped to the voltage across the smoothing capacitor C ₁ , which is a substantially constant voltage, and becomes substantially constant. Therefore, the capacitor C ₄ serves as a power source, and the leftward lamp current flowing from the point B to the point A in the figure is also substantially constant. The rightward lamp current flowing from point A to point B in the figure is the same as that in the first embodiment, but the crest factor of the lamp current flowing through the discharge lamp La can be improved as a whole.

Further, in the conventional discharge lamp lighting device, at the end of the life of the discharge lamp, the emitter of the filament on one side may decrease to show the diode characteristic.
When the lamp current flowing from the point B to the point A decreases due to a decrease in the emitter of the side filament, C of the capacitor C ₄
The charge charged to the side increases. Here, there is no problem if the discharge lamp La exhibits a perfect diode characteristic, but when the discharge lamp La exhibits an incomplete diode characteristic, a lamp current sometimes flows from the point B to the point A, and the capacitor C ₄ is charged. charges are released at a time through the inductor L _3, to charge the capacitor C _1. Therefore, there is a problem that the voltage across the capacitor C ₁ , that is, the voltage across the FET Q ₁ is boosted.

In this embodiment, the capacitor C_FourIs a dio
Mode D₁₃Through the capacitor C₁Connected to
Indexer C_FourThe voltage across the capacitor is capacitor C₁To the voltage across
Clamped. Capacitor C₁The capacitance of
Sensor C_FourSet to a value large enough for the capacitance of
Capacitor C_FourTo diode D₁₃Through
Capacitor C₁Even if electric charge flows to the capacitor C_FourElectric power
The pressure never rises above a certain voltage. Therefore,
Even at the end of the life of the discharge lamp La, FETQ ₁Both ends of
The voltage is substantially the same as the normal voltage of the discharge lamp La.

Since the configuration other than the diode D ₁₃ is the same as that of the first embodiment, its explanation is omitted. Further, in the present embodiment, the resonance capacitor C ₂ is connected in parallel with the FET Q ₁ , but the resonance capacitor C ₂ may be connected in parallel with the resonance inductor L ₂ to form a resonance circuit. In the first to seventh embodiments, the discharge lamp L is used as the load.
Although a is used, a load other than a discharge lamp may be used as long as it is a load that carries a high-frequency current, and it can be applied to a power supply device that reconverts a high-frequency voltage into a DC voltage. In addition, a plurality of loads may be used, and the loads may be connected in parallel or in series.

[0057]

As described above, the invention of claim 1 provides a rectifier circuit for rectifying an AC power source, a chopper circuit comprising a chopper inductor connected between output terminals of the rectifier circuit, and a series circuit of switching elements. A flywheel diode connected in anti-parallel to the switching element, a load connected in parallel to the switching element, and a control circuit for turning the switching element on and off at a high frequency, and the switching element and the control circuit form an inverter circuit. If the voltage across the switching element falls below a predetermined threshold, the control circuit turns on the switching element and the switching element turns on while the current flows through the flywheel diode.
After the voltage across the child drops below the threshold, the control circuit switches.
Switching the delay time before turning on the
It changes according to the peak value of the voltage across the element
Therefore, it is possible to prevent a rush current from being generated when the switching element is turned on, and it is possible to perform stable oscillation operation.

According to a second aspect of the present invention, there is provided an arrangement for rectifying an AC power supply.
Chopper connected between the current circuit and the output terminal of the rectifier circuit
Group consisting of a series circuit of inductor and switching element
The flipper circuit and the switch connected in anti-parallel with the switching element.
Parallel connection of lyfoil diode and switching element
Load and switching element on / off at high frequency
And a switching element and a control circuit
The inverter circuit is composed of and
When the voltage drops below a certain threshold, the flywheel diode
While the current is flowing through the control circuit, the control circuit
Is turned on and the threshold value is changed according to the peak value of the voltage across the switching element, and the invention of claim 3 raises the threshold value when the peak value of the voltage across the switching element is larger than a predetermined value. At the same time, when the peak value of the voltage across the switching element is smaller than the predetermined value,
Since lowering the threshold, the scan during on of switching element can rush current is prevented from occurring, there is an effect that enables stable oscillation operation.

According to a fourth aspect of the present invention, there is provided an arrangement for rectifying an AC power supply.
Chopper connected between the current circuit and the output terminal of the rectifier circuit
Group consisting of a series circuit of inductor and switching element
The flipper circuit and the switch connected in anti-parallel with the switching element.
Parallel connection of lyfoil diode and switching element
Load and switching element on / off at high frequency
And a switching element and a control circuit
The inverter circuit is composed of and
When the voltage drops below a certain threshold, the flywheel diode
While the current is flowing through the control circuit, the control circuit
Is turned on and the strength of voltage resonance of the inverter circuit is changed according to the peak value of the voltage across the switching element, and the invention of claim 5 changes the strength of voltage resonance by frequency modulation control. In the invention of claim 6 , when the peak value of the voltage across the switching element is larger than a predetermined value, the switching frequency is controlled to be high, and when the peak value of the voltage across the switching element is smaller than the predetermined value, Since the switching frequency is controlled to be low, the ripple of the voltage across the switching element can be reduced, and stable oscillation operation can be performed. Further, since the peak value of the voltage applied to the switching element is reduced, the withstand voltage of the switching element can be suppressed, and the reliability of the switching element can be improved. Further, there is an effect that the cost can be reduced by using a low rating element as the switching element.

[0060]

[0061]

According to the invention of claim 7 , since the load is constituted by the lighting load, there is an effect that the lighting load can be stably turned on.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a power supply device according to a first embodiment.

FIG. 2 (a) is a waveform diagram showing the waveform of each part in the peak portion of the input voltage of the same. (B) It is a waveform diagram which shows the waveform of each part in the valley part of the input voltage same as the above.

FIG. 3 is a circuit diagram showing a power supply device according to a second embodiment.

FIG. 4 is a waveform diagram showing the voltage of each part of the above.

FIG. 5 is a circuit diagram showing a power supply device according to a third embodiment.

FIG. 6 is a circuit diagram showing a power supply device according to a fourth embodiment.

FIG. 7 is a circuit diagram showing a power supply device according to a fifth embodiment.

FIG. 8 is a circuit diagram showing a power supply device according to a sixth embodiment.

FIG. 9 (a) is a circuit diagram showing a current flow in the peak portion of the input voltage of the same. (B) It is a circuit diagram which shows the flow of the electric current in the valley part of the input voltage same as the above.

FIG. 10 is a circuit diagram showing a power supply device according to a seventh embodiment.

FIG. 11 is a circuit diagram showing a conventional power supply device.

FIG. 12 is a waveform diagram showing the waveform of each part of the above.

FIG. 13 is a circuit diagram showing another conventional power supply device.

14 (a) to (c) are waveform charts showing waveforms of respective portions of the same.

[Explanation of symbols]

3 Control circuit AC AC power supply DB Full-wave rectifier circuit L ₂ Chopper inductor Q ₁ FET R ₁ , R ₂ Resistance D ₇ , D ₈ Diode

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-9-113557 (JP, A) JP-A-8-107682 (JP, A) JP-A-8-115792 (JP, A) JP-A-4- 271 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H02M 7/48 H02M 1/08 H02M 7/06 H05B 41/24

Claims (7)

(57) [Claims] 1. A rectifier circuit for rectifying an AC power supply; a chopper circuit comprising a series circuit of a chopper inductor and a switching element connected between output terminals of the rectifier circuit;
A flywheel diode antiparallelly connected to the switching element, a load parallelly connected to the switching element, and a control circuit for turning on / off the switching element at a high frequency are provided, and the switching element and the control circuit are combined. constitute an inverter circuit, when the voltage across the switching element is below a predetermined threshold value, while the current is flowing in the flywheel diode, together with the control circuit turns on the switching element, the Sui
After the voltage across the switching element falls below the threshold,
The delay until the control circuit turns on the switching element
Is the peak value of the voltage across the switching element.
A power supply device characterized in that it is changed according to . 2. A rectifier circuit for rectifying an AC power supply, and the rectifier
A chopper inductor connected between the output terminals of the circuit
A chopper circuit consisting of a series circuit of switching elements,
Flywheel connected in anti-parallel to the switching element
A diode and the switching element are connected in parallel.
The load and the switching element are turned on / off at high frequency.
And a control circuit for controlling the switching element and the control circuit.
The inverter circuit is composed of the control circuit and the switching
When the voltage across the device falls below a predetermined threshold, the flywheel
Control circuit while current flows through the diode.
Turns on the switching element, and
According to the peak value of the voltage across the switching element
A power supply device characterized by being changed . 3. The peak of the voltage across the switching element
If the value is larger than the predetermined value, increase the threshold value.
In both cases, the peak value of the voltage across the switching element is
If it is smaller than the specified value, lower the threshold value.
The power supply device according to claim 2 , wherein the power supply device is a power supply device. 4. A rectifier circuit for rectifying an AC power supply, and the rectifier
A chopper inductor connected between the output terminals of the circuit
A chopper circuit consisting of a series circuit of switching elements,
Flywheel connected in anti-parallel to the switching element
A diode and the switching element are connected in parallel.
Of on / off load and, the switching element at high frequencies
And a control circuit for controlling the switching element and the control circuit.
The inverter circuit is composed of the control circuit and the switching
When the voltage across the device falls below a predetermined threshold, the flywheel
Control circuit while current flows through the diode.
Turns on the switching element, and
Depending on the peak value of the voltage across the
A power supply device characterized in that the strength of voltage resonance of a power circuit is changed . 5. The frequency modulation control is based on the change in the strength of voltage resonance.
The power supply device according to claim 4, further comprising: 6. The peak of the voltage across the switching element
If the value is greater than the given value, the switching frequency
To control the peak voltage of both ends of the switching element.
If the frequency value is less than the specified value, the switching frequency
6. The power supply device according to claim 5, wherein the power supply is controlled to be low . 7. The load comprises a lighting load.
The power supply device according to claim 1 , wherein the power supply device is a power supply device .