JP3327011B2 - Power converter - 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 converter for obtaining AC power from a DC power supply, and more particularly to a power converter for obtaining AC power using a switched capacitor.

[0002]

2. Description of the Related Art Japanese Patent Application No. 6-24974 discloses a circuit for obtaining an AC output from a DC power supply using a switched capacitor.
FIG. 9 shows a circuit diagram and FIG. 10 shows an operation waveform diagram.

[0003] This circuit is composed of a DC power source E and an inductance.
Element L₁Via a power supply capacitance element (hereinafter, referred to as
It is called a capacitance element. ) C₁~ C_FiveTo V_Ten<V₂₀
<V ₃₀<V₄₀<V₅₀Charge to different voltages according to the voltage relationship of
Switching element S_z1~ S_z4And switching element S_z1~
S_z4Z and load capacitor whose polarity is inverted by
Element C_ZIn the load circuit 1 composed of
Sensing element L_TwoVia the capacitance element C₁~ C_FiveTo
By connecting in order, the voltage across the load Z (load voltage
Pressure) Vz is smoothly changed to reduce distortion of load voltage Vz
And the inductance element L₁, L_Two
Power transmission effect through the
It improves the rate.

In this conventional example, the current I ₁ from each of the capacitance elements C _{1 to} C ₅ to the load circuit ₁ is equal to the load voltage V
At the time _Z rises to the load circuit 1 from the capacitance element C ₁ -C _5, at the time the load voltage V _Z falling flowing from the load circuit to the respective capacitance elements C ₁ -C _5. That is, a bidirectional current flows through the switching elements S ₁₂ , S ₂₂ , S ₃₂ , S ₄₂ , and S ₅₂ . However, bipolar transistors, MOSFE
Since T and the like are unidirectional elements, deterioration occurs when a bidirectional current flows. Here, a switching element for preventing deterioration of the one-way element is required. As shown in FIG. 11, for example for its, gate - DOO, source - Body between scan diode - de D _a, MOSFET having a D _b (Q _a), source of the (Q _b) - connects the scan comrades MOSFET (Q _a ), (Q _b )
A circuit that connects the drains A and B to the current path can be considered. As shown in FIG. 11, MOSFET (Q _a ), (Q _b )
The gate - DOO, source - by applying a control signal VS between scan, MOSFET (Q _a), it becomes possible to flow a bidirectional current (Q _b). FIG. 12 is a circuit diagram in which all the switching elements in the circuit shown in FIG. 9 are replaced with MOSFETs having a body diode between the gate and the source.

[0005] In the circuit shown in FIG.
Is a high-side switch having an unstable source potential, the high-side switch is driven by a control signal transmission / drive circuit as shown in FIG. Further, a MOSFET (S) constituting a bidirectional switching element as shown in FIG.
_{j2a), (S j2b) (} j = 1~5) , the switching element S _j2 (j = 1~ by applying a control signal VS simultaneously
The operation is performed as in 5), and the operation conforms to the operation waveform diagram shown in FIG.

[0006]

[SUMMARY OF THE INVENTION] However, in the above-mentioned prior art, for example, the control signal of the switching element S ₁₂ at time t ₂ is B - level, the control signal of the switching element S ₂₂ becomes a high level, the switching element S ₁₂ is data - by turning the switching element S ₂₂ is before completely dead off because of the turnoff time, the capacitance element C
Thus a current flows through the capacitance element C _{1 2} through the switching element S _22, S _12, that is, when at least two of the switching elements S _j2 (j = 1~5) but becomes a state to be turned on simultaneously, At least two of the capacitance elements C _j (j = 1 to 5) are electrically connected to each other, and a current flows directly between the capacitance elements C _j (j = 1 to 5).
Is different from the set voltage, and a first problem occurs that a loss occurs.

In order to solve the first problem, it is necessary to control the switching elements S _j2 (j = 1 to 5) so as not to turn them on simultaneously in consideration of the turn-off time.
Alternatively, a second problem arises in that a switching element that turns on and off at high speed must be used.

The present invention has been made in view of the above problems, and an object of the present invention is to use a switched capacitor which prevents deterioration of a switching element, has high circuit efficiency, and has low input distortion. An object of the present invention is to provide a power conversion device.

[0009]

A load, a plurality of power supply capacitance elements, a first inductance element connected to a DC power supply, and the plurality of power supply capacitances via the first inductance element. a charging means for charging a substantially predetermined voltage to the device, contact in parallel with the load
Wherein a connection has been load capacitance elements, a second inductance element connected in series parallel circuit between the load and the load capacitance elements, a series circuit consisting of the parallel circuit and the second inductance element more A plurality of switching elements connected in series between the power supply capacitance elements and the plurality of power supply capacitance elements are selectively switched and connected to the series circuit via the second inductance element. The negative
Control means for changing the voltage across the load capacitance element in a substantially pulsating waveform by charging / discharging the load capacitance element; and connecting to the DC power supply via the first inductance element, And a charging / discharging means for charging / discharging the charging current control capacitance element, wherein the plurality of switching elements include a body diode. Source and drain electrodes of two MOSFETs each having a gate connected to each other, and MOSFET control means for turning on the two MOSFETs one by one without turning them on at the same time. Power converter.

According to the second aspect of the present invention, the MOSFE
T is a vertical MOSFET having a vertical structure and is characterized by connecting drain electrodes of the vertical MOSFET.

According to the third aspect of the present invention, the plurality of switching elements connect the emitter electrodes or the collector electrodes of two bipolar transistors, and each of the two bipolar transistors And a diode connected in anti-parallel between the collector and the emitter.

According to the fourth aspect of the present invention, the plurality of switching elements include two M diodes having no body diode.
OSFET having drain electrodes or source electrodes connected to each other and having a diode connected in anti-parallel between the drain and source of each of two MOSFETs having no body diode. It is characterized by that.

According to a fifth aspect of the present invention, the load is a bridge circuit comprising at least a plurality of switching elements, a load capacitance element, and a second inductance element.

According to a sixth aspect of the present invention, the load is a discharge lamp. According to the invention described in claim 7, the load is constituted by at least a bridge circuit and a discharge lamp.

[0015]

According to the first aspect of the present invention, when a current flows from a plurality of capacitance elements for power supply to a load circuit, the first MOSFET having a body diode is turned off and the first MOSFET having a body diode is turned off. The second MOSFET is turned on, and the body diode of the first MOSFET and the second MOSFET are turned on.
A plurality of power supply capacitance elements are connected to the load circuit via the inductance element. When a current flows from the load circuit to a plurality of power supply capacitance elements, the first MOSFET is turned on, and the second MOSFET is turned on.
To turn off the body diode of the second MOSFET,
A plurality of power supply capacitance elements are connected to the load circuit via the second inductance element.

According to the second aspect of the present invention, in the semiconductor structure of a plurality of switching elements, the first vertical MOS
The drain electrode of the FET and the second vertical MOSFET are made common.

According to the third aspect of the present invention, when a current flows from a plurality of capacitance elements for power supply to a load circuit, the first bipolar transistor is turned off and the second bipolar transistor is turned on. A first diode and a second diode connected in anti-parallel to the first bipolar transistor.
A plurality of power supply capacitance elements are connected to the load circuit via the inductance element. When a current flows from the load circuit to a plurality of power supply capacitance elements, the first bipolar transistor is turned on, the second bipolar transistor is turned off, and the current is supplied to the second bipolar transistor in reverse. A second diode connected in parallel, a second
A plurality of power supply capacitance elements are connected to the load circuit via the above inductance element.

According to the fourth aspect of the present invention, when a current flows from a plurality of power supply capacitance elements to a load circuit, the first MOSFET having no body diode is provided.
Off, a second MOSFET having no body diode
T is turned on, and a plurality of power supply capacitance elements are connected to the load circuit via a first diode and a second inductance element connected in antiparallel to the first MOSFET. When a current flows from the load circuit to the plurality of power supply capacitance elements, the first MOSFET is turned on, the second MOSFET is turned off, and the second MOSFET is turned on.
A plurality of power supply capacitance elements are connected to the load circuit via a second diode and a second inductance element connected in anti-parallel to T.

According to the fifth aspect of the present invention, when a current flows from a plurality of power supply capacitance elements to a load circuit, the first MOSFET having a body diode is turned off and the first MOSFET having a body diode is turned off. The second MOSFET is turned on, and a plurality of power supply capacitance elements are connected to the load circuit via the body diode of the first MOSFET and the second inductance element. When a current flows from the load circuit to the plurality of power supply capacitance elements, the first MOSFET is turned on and the second MOSFET is turned on.
T is turned off and the body diode of the second MOSFET is turned off.
And a plurality of power supply capacitance elements connected to the load circuit via the second inductance element.

Further, the voltage of the load capacitance element is reduced to zero by disconnecting the plurality of power supply capacitance elements from the load.

According to the sixth and seventh aspects of the present invention, the discharge lamp is stably lit by supplying AC high frequency power to the discharge lamp.

[0022]

【Example】

(Embodiment 1) A circuit diagram of a first embodiment according to the present invention is shown in FIG.
FIG. 2 is a circuit diagram of the switching element S _j2 (j = 1 to 5), and FIG. 3 is an operation waveform diagram.

The difference from the conventional example shown in FIGS. 10 to 12 is that the MOSFET (Q _a ) having a body diode constituting the switching element S _j2 (j = 1 to 5),
(Q _b) of the gate - omitted independently control signals between scan VS _a, and by providing the VS _b, a description by the same reference symbols are affixed to the other prior art example having the same configuration - DOO, Seo .

Next, the operation will be briefly described with reference to FIG.
You. Capacitance element C₁~ C_FiveTo load circuit 1
Style I₁Time t₀~ T _FiveIs a MOSFET
(S_j2a) (J = 1 to 5) are turned off, and the MOSFET (S
_j2b) (J = 1 to 5) to turn on the inductance element
L_TwoVia the capacitance element C_j(J = 1 to 5)
Connect to load circuit 1. For example, time t_TwoMOSFE
T (S_32b) Is set to high level,
Citance element C_Three→ MOSFET (S_32b) → MOSF
ET (S_32a) Body diode → inductance element
Child L_Two→ Current flows through the load circuit 1. At this time, time t
₁~ T_TwoS was on until_22bTurns off completely
MOSFET (S_22a) Is off
The capacitance element C_ThreeFrom the capacitance element C
_TwoNo current flows into.

On the other hand, MOSFET constituting the load circuit 1
(S _Z1) ~ body diode of (S _Z4) - Time t ₅ ~t ₁₀ supplying a current I ₁ to the capacitance element C _{j (j} = 1~5) through the _{soil, MOSFET (S j2a) (j} = 1-5)
ON, and turns off the _{MOSFET (S j2 b) (j} = 1~5), to connect the capacitance element C _{j (j} = 1~5) in the load circuit 1 via the inductance element L _2. For example, time t ₆ ~t ₇ to MOSFET (S _42a) is turned on, the control signal b of the MOSFET (S _42a) at time t ₇ - level, the control signal of the MOSFET (S _32a) becomes a high level, MOSFET ( _S32a ) turns on. At this time, MOSFET for (S _42a) is MOSFET even when no fully and completely off (S _42b) is turned off, the capacitance element C from the capacitance element C _4
No current flows through ₃ . For better capacitance element C ₃ is lower voltage than the load circuit 1, a current flows from the load circuit 1 to the capacitance element C _3.

Between times t _{4 and} t ₆ , the capacitance element C ₅ is connected to the load circuit 1, and the current flows in a resonant manner, so that the period during which the current flows from the capacitance element C ₅ to the load circuit 1 and the load it may be difficult to separate from the circuit 1 exactly the period in which current flows through the capacitance element C _5. In this case, between times t ₅ ~t _6, and the time t ₆ fully on the MOSFET (S _{52 b)} so as to turn on at time t ₅ before and MOSFET (S _42b)
After the MOSFET is completely turned off, the MOSFET (S _{52 a} ) is turned on, whereby the MOSFET (S _{52 a} ) and the MOSFE are turned on.
A period during which T (S _52b ) and T (S _52b ) are simultaneously turned on is provided, and a bidirectional switch operation is performed.

With the above configuration, it is not necessary to consider the turn-off delay of the bidirectional switch, so that control can be simplified and a switching element with a slow turn-off can be used. . In addition, MOSFET
(Q _a), instead of (Q _b), as shown in FIG. 4, Baipo - La transistor and Baipo - diode is connected in antiparallel La transistor - de _{D j2a, D j2b (j =} 1~5) And may be composed of Further, a MOSFET having no body diode may be used instead of the bipolar transistor.

(Embodiment 2) FIG. 5 is a circuit diagram and FIG. 6 is an operation waveform diagram of a second embodiment according to the present invention.

The difference from the first embodiment shown in FIG. 1 is that a load capacitance element C _Z is connected in parallel with the load _Z ,
And an inductance element L ₂ connected load Z series, by arranging in a full bridge circuit composed of at least _{MOSFET (S Z1) ~ (S} Z4), the load circuit 1
When returning power from the power supply to the power supply capacitance elements C _{1 to} C ₅ , the MOSFETs (S _Z1 ) to (S _Z4 ) do not need to use a bidirectional switching element. The same components as those described above are denoted by the same reference numerals and description thereof will be omitted.

Next, the operation will be briefly described with reference to FIG. During the time _{t 0 ~t 10, MOSFET (S} Z1),
(S _Z2 ) is turned on, and V _Z becomes a positive voltage.

For example, at time t₀In the MOSFET
(S_12b) Is turned on, the capacitance element C₁→ M
OSFET (S_12b) → MOSFET (S_12a) Body
Diode → MOSFET (S_Z1) → Inductance
Element L_Two→ Capacitance element C for load_Z, From load Z
Parallel circuit → MOSFET (S_Z2) → Capacitance
Element C₁Current flows in the path of
You. Time t₁~ T_FiveIn the same way, the capacitance
Element C_Two~ C_FiveTo MOSFET (S_Z1), (S _Z2)
Power to the load Z via the Load capacitance
Element C_ZFrom the capacitance element C_FiveTo return power to
(Time t_Five), MOSFET (S_52a),
Inductance element L_Two→ MOSFET (S_Z1) Body
Diode → MOSFET (S_52a) → MOSFET
(S_52b) Body diode → capacitance element C
_Five→ MOSFET (S_Z2) On the body diode path
Electric current flows. At this time, the MOSFET (S_Z3),
(S_Z4) Is off, so the load capacitance element
Child C_Z→ Inductance element L_Two→ MOSFET
(S_Z1) Body diode → MOSFET (S_Z3) →
Load capacitance element C_ZOr load capacity
Citance element C_Z→ Inductance element L_Two→ MOSF
ET (S_Z4) → MOSFET (S_Z2) Body dio-
→ Load capacitance element C_ZCurrent in the path of
Not.

[0032] between the time t ₁₀ ~t ₁₁ is, MOSFET (S
_Z2), (S _Z4) is turned on capacitance element C ₁ -C
By separating ₅ from the load Z, the load capacitance element C _Z → the inductance element L ₂ → MOSFET
_{(S Z4) → MOSFET (S} Z2) → current flows in path of the load capacitance element C _Z is the voltage of the load capacitance element C _Z zero.

During the period from time t _{11 to} t ₂₂ , the MOSFET (S
_Z3), which is V _Z is a negative voltage is turned on (S _Z4).

[0034] Incidentally, MOSFET (Q _a), instead of (Q _b), as shown in FIG. 4, Baipo - La transistor and Baipo - diode is connected in antiparallel La transistor - de _{D j2 a,} D j2b (J = 1 to 5). Further, a MOSFET having no body diode may be used instead of the bipolar transistor.

(Embodiment 3) FIG. 7 shows a circuit diagram of a third embodiment according to the present invention, and FIG. 8 shows a semiconductor structure thereof.

The difference from the first embodiment shown in FIG.
Vertical MOSFET (Q _a), (Q_b)
That the drains of the vertical MOSFETs are connected
The same reference numerals are used for the same components as those of the first embodiment.
The description will be omitted by attaching.

[0037] With the arrangements in this way, the vertical MOSFET as shown in FIG. 8 (Q _a), it is possible in common (Q _b) is a drain electrode, the vertical MOSFET (Q _a),
(Q _b ) can be easily integrated into one chip and used as one device. Although the VDMOS structure is shown in FIG. 8 in this embodiment, any structure may be used as long as it has a vertical structure, and the structure may be used in the first and second embodiments. Is also good.

Further, in the first to third embodiments, a switching element having a slow turn-off may be used.

[0039]

According to the first, third, and fourth aspects of the present invention,
Prevents deterioration of switching elements, has high circuit efficiency,
It is possible to provide a power conversion device that uses a switched capacitor and has little input distortion.

According to the second aspect of the invention, the deterioration of the switching element is prevented, the circuit efficiency is high, the input distortion is small, and the drain electrodes of the two vertical MOSFETs can be shared. MOSFET can be easily integrated into one chip and used as one device.
A power converter using a switched capacitor can be provided.

According to the fifth aspect of the invention, it is necessary to prevent deterioration of the switching element, to have high circuit efficiency, to reduce input distortion, and to use a bidirectional switching element as a switching element constituting a load circuit. A power converter using a switched capacitor can be provided.

According to the present invention, there is provided a power conversion device using a switched capacitor, which prevents deterioration of a switching element, has high circuit efficiency, has low input distortion, and can stably turn on a discharge lamp. Can be provided.

According to the seventh aspect of the present invention, the deterioration of the switching element is prevented, the circuit element has a high circuit efficiency, the input distortion is small, the discharge lamp can be stably operated, and the switching element constituting the load circuit is provided. Can provide a power converter using a switched capacitor, which does not require the use of a bidirectional switching element.

[Brief description of the drawings]

FIG. 1 shows a circuit diagram of a first embodiment according to the present invention.

FIG. 2 shows a circuit diagram of a switching element according to the embodiment.

FIG. 3 shows an operation waveform diagram according to the embodiment.

FIG. 4 shows another circuit diagram according to the embodiment.

FIG. 5 shows a circuit diagram of a second embodiment according to the present invention.

FIG. 6 is an operation waveform diagram according to the embodiment.

FIG. 7 shows a circuit diagram of a third embodiment according to the present invention.

FIG. 8 shows a semiconductor structure diagram according to the above embodiment.

FIG. 9 shows a circuit diagram of a conventional example according to the present invention.

FIG. 10 shows an operation waveform diagram according to the above conventional example.

FIG. 11 is a circuit diagram of a switching element according to the conventional example.

FIG. 12 shows another circuit diagram of a conventional example according to the present invention.

FIG. 13 is a circuit diagram of a control signal transmission / drive circuit according to the conventional example.

[Explanation of symbols]

 C Capacitance element D Diode E Power supply L Inductance element S Switching element Z Load 1 Load circuit

Claims (7)

(57) [Claims] 1. A load, a plurality of power supply capacitance elements, a first inductance element connected to a DC power supply, and substantially predetermined power supply capacitance elements via the first inductance element. Charging means for charging the load , a load capacitance element connected in parallel to the load , a second inductance element connected in series to a parallel circuit of the load and the load capacitance element, and the parallel circuit And a plurality of switching elements connected in series between the series circuit including the second inductance element and the plurality of power supply capacitance elements, and alternatively switching the plurality of power supply capacitance elements. the connected in series circuit the
The load capacitor via the inductance element
Control means for changing the voltage across the load capacitance element in a substantially pulsating waveform by charging / discharging the capacitance element; and connecting the plurality of power supply capacitances to the DC power supply via the first inductance element. In a power conversion device including a charging current control capacitance element for controlling a charging current to an element, and charging / discharging means for charging / discharging the charging current control capacitance element, the plurality of switching elements include a body diode. The source and drain electrodes of two MOSFETs are connected to each other, and the two MOSFETs are turned on one by one without being turned on at the same time.
A power conversion device comprising OSFET control means. 2. The vertical MOSFET according to claim 1, wherein the MOSFET is a vertical MOSFET having a vertical structure.
The power converter according to claim 1, wherein the drain electrodes are connected to each other. 3. The plurality of switching elements according to claim 1, wherein the plurality of switching elements are formed by connecting emitter electrodes or collector electrodes of two bipolar transistors, and each of the two bipolar transistors is connected to each other. A power converter having a diode connected in anti-parallel between a collector and an emitter. 4. The two switching elements according to claim 1, wherein the plurality of switching elements have two MOSFETs without a body diode.
A diode in which T drain electrodes or source electrodes are connected, and a diode connected in anti-parallel between the drain and source of each of the two MOSFETs having no body diode. A power converter, comprising: 5. The load according to claim 1, wherein the load is a bridge circuit including at least the plurality of switching elements, the load capacitance element, and the second inductance element. 5. The power converter according to any one of 4. 6. The power converter according to claim 1, wherein the load is a discharge lamp. 7. The load according to claim 1, wherein the load comprises at least the bridge circuit and a discharge lamp.
The power converter according to any one of claims 5 to 5.