JPH07123736A - Inverter device - Google Patents

Abstract

PURPOSE:To provide an inverter device which can improve the distortion of input currents, can suppress the occurrence of rush currents at the time of making power supply, can cope with a wide range of power supply voltages, and has simple constitution. CONSTITUTION:An inverter device is provided with a step-down chopper circuit 1 which outputs a smoothed DC voltage to an electrolytic capacitor C1 through a switching element and inductor by rectifying AC power supply VS and an inverter circuit 2 which supplies the smoothed DC voltage to a load 3 after converting the voltage into a high-frequency voltage. the inverter circuit 2 is provided with a switching element which also works as a step-up or step-up and down chopper. The inverter device is also provided with a control circuit 4 which can make the circuits 1 and 2 to work as step-down, step-up and down, and step-up chopper circuits by controlling the turning on/off timing of the switching elements of the circuits 1 and 2.

Description

Detailed Description of the Invention

[0001]

The present invention relates to rectifying a commercial AC power supply.
The present invention relates to an inverter device which converts a smoothed DC power supply into a high frequency and supplies it to a load, and is used, for example, in an electronic ballast of a high frequency lighting device of a discharge lamp.

[0002]

2. Description of the Related Art FIG. 5 is a circuit diagram of a conventional inverter device. In the figure, 11 is a step-up chopper, 12 is a half bridge inverter, and 13 is an inrush current suppressing circuit. The circuit configuration will be described below. The AC power supply Vs is connected to the AC input terminal of the diode bridge DB via the filter circuit FT. The DC output terminal of the diode bridge DB has an inductor L2 and a transistor Q3.
Are connected in series via the inrush current suppressing circuit 3. A smoothing capacitor C1 is connected to both ends of the transistor Q3 via a diode D3. A series circuit of transistors Q1 and Q2 and a series circuit of capacitors C3 and C4 are connected in parallel to both ends of the capacitor C1. Diodes D1 and D2 are connected in antiparallel to the transistors Q1 and Q2, respectively. A discharge lamp La is connected as a load between a connection point of the transistors Q1 and Q2 and a connection point of the capacitors C3 and C4 via a resonance inductor L1. A resonance capacitor C2 is connected in parallel between the non-power supply side terminals of the filament of the discharge lamp La. In the half-bridge inverter 12, the transistors Q1 and Q2 are alternately turned on / off, and a high frequency sine wave voltage is applied to the discharge lamp La by the resonance action of the inductor L1 and the capacitor C2. Also,
In the step-up chopper 11, the transistor Q3 is turned on and off, and the inductor L is turned on when the transistor Q3 is turned on.
2 stores electromagnetic energy according to the power supply voltage, and when the transistor Q3 is off, the power supply voltage and the induced voltage of the inductor L2 are superimposed to charge the capacitor C1. The filter circuit FT removes the high frequency component of the switching current flowing through the boost chopper 11. The rush current suppressing circuit 13 generally uses a thyristor Q5 as shown in FIG. In this circuit, the thyristor Q5 connected in parallel with the resistor R is turned off when the power is turned on, and when a predetermined time elapses after the power is turned on, the thyristor Q5 is turned on by being triggered by the timer circuit 15. Therefore, after the power is turned on, the inrush current is suppressed by the resistor R for a predetermined time, and after the elapse of the predetermined time, the resistor R
The power loss due to the resistance R is reduced by the conduction of the thyristor Q5 connected in parallel with the thyristor Q5. Further, as shown in FIG. 7, there is a circuit in which a switching element Q4 such as a bipolar transistor is simply connected. In this case, zero-cross switching for turning on the switching element Q4 near 0 volt of the power supply voltage is performed. Is common.

[0003]

There are two problems of such an inverter device: improvement of input current distortion and suppression of inrush current when power is turned on. Further, it is necessary to cope with a wide range of power supply voltages around the world. (For example, 100V, 2
It must be possible to use all of 00V and 240V). Among them, the improvement of the input current distortion, which is a problem, is satisfied because the step-up chopper supplies a current substantially proportional to the power supply voltage. In addition, the problem of suppressing the inrush current when the power is turned on can be satisfied by the inrush current suppressing circuit. Furthermore, in order to deal with a wide range of power supply voltages in the world, which is a problem, the output voltage of the boost chopper, that is, the voltage of the capacitor C1 may be controlled to be constant regardless of the power supply voltage. However, this control is performed by changing the on-duty or the switching frequency of the transistor Q3 in the step-up chopper, but this change width must be considerably widened, and the control circuit becomes complicated. Further, in addition to this, if the output of the inverter is changed, that is, if it is applied even when the load changes, the control becomes more complicated and the design becomes difficult. Further, in the conventional example of FIG. 5, a boost chopper is required to improve the input current distortion, and a thyristor or the like is provided to suppress the inrush current.
This requires individual pieces, which increases the cost and complicates the circuit.

The present invention has been made in view of the above points, and an object thereof is to improve input current distortion, suppress inrush current at power-on, and cope with a wide range of power supply voltages. An object of the present invention is to provide an inverter device having a simple configuration that can be performed.

[0005]

In order to solve the above-mentioned problems, in the inverter device of the present invention, as shown in FIG. 1, an AC power supply Vs is rectified and electrolyzed via a switching element and an inductor. The capacitor C1 includes a step-down chopper circuit 1 that outputs a smoothed DC voltage, and an inverter circuit 2 that converts the smoothed DC voltage into a high frequency and supplies the load 3 to a load 3. The inverter circuit 2 also functions as a step-up or step-up / down chopper. A switching element of the step-down chopper circuit 1 and an inverter circuit 2 having a switching element.
The control circuit 4 is capable of controlling the on / off timing of the switching element and operating as a chopper circuit for any of step-down, step-up / step-down, and step-up.

[0006]

According to the present invention, the input current distortion can be improved by performing the operation of either the step-up chopper or the step-up / step-down chopper, and the operation of either the step-down chopper or the step-up / step-down chopper can be performed. Thus, the inrush current can be suppressed. Furthermore, by switching a plurality of chopper operations, it is possible to handle a wide range of power supply voltages. For more detailed operation of the present invention,
This will be described in detail in the following description of the embodiments.

[0007]

FIG. 2 is a circuit diagram of the first embodiment of the present invention.
The circuit configuration will be described below. The AC power supply Vs is connected to the AC input terminal of the diode bridge DB via the filter circuit FT. Diode bridge DB
Inductor L2 and transistor Q
A series circuit of 1 and Q3 is connected. Inductor L2
A smoothing capacitor C1 is connected to both ends of the capacitor via a diode D4. At both ends of the capacitor C1,
A series circuit of capacitors C3 and C4 and a transistor Q
A series circuit of 1 and Q2 is connected in parallel. A diode D is provided on each side of the transistors Q1 and Q2.
1 and D2 are connected in anti-parallel. Transistor Q1,
The discharge lamp La is connected between the connection point of Q2 and the connection points of the capacitors C3 and C4 via the resonance inductor L1. A resonance capacitor C2 is connected in parallel between the non-power supply side terminals of the filament of the discharge lamp La.
The transistors Q1, Q2 and Q3 are on / off controlled by a control circuit S, respectively. In this embodiment, the transistor Q3 forming the step-down chopper is used as an inrush current suppressing circuit, and the transistor Q3 is also used.
1 is also used as a switching element for the step-up chopper and the step-up / step-down chopper. Also, the transistor Q
1 is also used as a switching element of a half-bridge inverter. In this embodiment, the control circuit S controls the mutual timings of the transistors Q1, Q2, Q3 so that the step-down chopper, the step-up / down chopper, and the step-up chopper can operate.

The operation of this embodiment will be described below.
First, the step-down chopper operation will be described. In the step-down chopper operation, the transistor Q3 and the transistor Q1
Performs an inversion operation. When the transistor Q3 is on, the transistor Q1 is off, and the transistor Q2 is on,
A current flows through a path that passes through the diode bridge DB, the inductor L2, the capacitor C1, the diode D2, the transistor Q3, and the diode bridge DB. When the transistor Q3 is off, the transistor Q1 is on, and the transistor Q2 is off, a current flows in a path that passes through the inductor L2, the capacitor C1, the diode D4, and the inductor L2. In this way, if the transistor Q1 and the transistor Q2 are turned on / off so as to oppose each other, the half-bridge inverter operates and a high frequency can be output to the load.

Next, the step-up / down chopper operation will be described. In the step-up / down chopper operation, the transistor Q3 and the transistor Q1 operate in synchronization. Transistor Q
3. When the transistor Q1 is on, a current flows in a path that passes through the diode bridge DB, the inductor L2, the transistor Q1, the transistor Q3, and the diode bridge DB. Also, the transistor Q3 and the transistor Q
When 1 is off, inductor L2 and capacitor C
A current flows through a path that passes through 1, the diode D4, and the inductor L2. Also in this case, the transistors Q1 and Q2 are turned on / off so as to be opposite to each other, the half-bridge inverter operates, and a high frequency can be output to the load.

Next, the step-up chopper operation will be described. In the boost chopper operation, the transistor Q3 is always on. And when the transistor Q1 is on,
A current flows through a path that passes through the diode bridge DB, the inductor L2, the transistor Q1, the transistor Q3, and the diode bridge DB. When the transistor Q1 is off, the diode bridge DB and the inductor L
2, capacitor C1, diode D2, transistor Q
3. The current flows through the path passing through the diode bridge DB. Also in this case, the transistors Q1 and Q2 are turned on / off contrary to each other to operate as an inverter.

As described above, when the transistor Q3 is operated by reversing the transistor Q1, the step-down chopper operation is performed, and when the transistor Q3 is operated in synchronization with the transistor Q1, the buck-boost chopper operation is performed and the transistor Q3 is always on. Then, the boost chopper operation is performed. Further, during the step-up / step-down chopper operation and step-up chopper operation, since a current flows through the transistor Q1, it can be seen that the transistor Q1 doubles as a switching element of the step-up / step-down chopper and the step-up chopper. Therefore, if the control circuit S controls ON / OFF of the transistor Q3 or synchronous inversion of the transistors Q3 and Q1, it functions as any of the above choppers. An operation example using the above properties is shown below.

First, in order to suppress the inrush current when the power is turned on, the transistor Q3 is charged until the capacitor C1 is charged.
Is operated by inverting the transistor Q1, and the transistors Q1 and Q2 are alternately turned on and off. As a result, the step-down chopper operates and the inrush current can be suppressed. In particular, by appropriately changing the on-time of the transistor Q3,
It is effective to control so that the capacitor C1 is gradually charged. When the capacitor C1 is in a stationary state after being charged, the transistor Q3 is always turned on, and the transistors Q1 and Q2 are alternately turned on / off to operate as a step-up chopper to improve the input current distortion.

Further, as a case of supporting a wide range of power supply voltages, for example, when the circuit is shared for 100 V and 200 V, the transistors Q3 and Q1 are set at 200 V.
To operate step-up / down chopper by synchronizing
When the voltage is 00V, the transistor Q3 is always turned on to perform the boost chopper operation, thereby controlling the voltage of the capacitor C1 to be the same. According to this, control becomes much easier than in the conventional example. Further, compared to the conventional example, the number of main circuit components is hardly increased, and three types of chopper operations of boosting, step-up / step-down, and stepping-down can be performed only by changing the on / off timings of the switching elements of the inverter and the chopper.

The switching of the chopper operation is performed by the AC power source V
The switching may be performed not only according to the rating of 100V and 200V of s, but also according to the change of the power supply voltage within the commercial cycle. For example, when the peak of the power supply voltage is Vp, the boost chopper may be used when the power supply voltage is lower than Vp / 2, and the buck-boost chopper may be used when the power supply voltage is higher than Vp / 2. In this embodiment, the load is a discharge lamp, but the load is not limited to the discharge lamp, and is not limited to the resonance circuit of the inductor L1 and the capacitor C2.

FIG. 3 is a circuit diagram of the second embodiment of the present invention. The circuit configuration will be described below. AC power supply V
s is a diode bridge DB through the filter circuit FT
It is connected to the AC input terminal of. A series circuit of an inductor L2 and transistors Q2 and Q3 is connected to the DC output terminal of the diode bridge DB. A smoothing capacitor C1 is connected to both ends of the inductor L2 via a diode D4 and a diode D1. A series circuit of capacitors C3 and C4 and a series circuit of transistors Q1 and Q2 are connected in parallel to both ends of the capacitor C1. Diodes D1 and D2 are respectively connected in antiparallel to both ends of the transistors Q1 and Q2. Connection points of transistors Q1 and Q2 and capacitors C3 and C
The discharge lamp La is connected between the four connection points via the resonance inductor L1. A resonance capacitor C2 is connected in parallel between the non-power supply side terminals of the filament of the discharge lamp La. The transistors Q1, Q2 and Q3 are on / off controlled by a control circuit S, respectively. In this embodiment, the transistor Q3 forming the step-down chopper is used.
Is used as an inrush current suppression circuit,
The transistor Q2 is also used as a switching element for the step-up chopper and the step-up / step-down chopper. Also,
The transistor Q1 is also used as a switching element of a half bridge inverter. In this embodiment, the mutual timings of the transistors Q1, Q2, Q3 are controlled so that any of the step-down chopper, step-up / step-down chopper, and step-up chopper can operate.

The operation of this embodiment will be described below.
First, when performing the step-down chopper operation, the transistor Q2 needs to be always off. Therefore, in this embodiment, the inverter operation cannot be performed during the step-down chopper operation. When transistor Q3 is on, diode bridge DB, inductor L2, diode D1, capacitor C1, transistor Q3, diode bridge DB
An electric current flows along the path passing through. When the transistor Q3 is off, a current flows in a path that passes through the inductor L2, the diode D1, the capacitor C1, the diode D4, and the inductor L2. Therefore, regardless of whether the transistor Q3 is on or off, a current flows through the diode D1, so that the transistor Q1 cannot be controlled and the transistor Q2 must be always off. Therefore, the step-down chopper operation is possible, but the inverter operation is not possible.

Next, when the buck-boost chopper operation is performed, the transistors Q3 and Q2 are turned on / off in synchronization. First, when the transistors Q3 and Q2 are on, the diode bridge DB and the inductor L
2, a current flows through a path passing through the transistor Q2, the transistor Q3, and the diode bridge DB. When the transistors Q3 and Q2 are off, current flows in a path that passes through the inductor L2, the diode D1, the capacitor C1, the diode D4, and the inductor L2. In this case, the inverter operation can be performed by alternately turning on / off the transistors Q1 and Q2.

Next, when the boost chopper operation is performed, the transistor Q3 is always on. When the transistor Q2 is on, a current flows in a path that passes through the diode bridge DB, the inductor L2, the transistor Q2, the transistor Q3, and the diode bridge DB. When the transistor Q2 is off, a current flows through the diode bridge DB, the inductor L2, the diode D1, the capacitor C1, the transistor Q3, and the diode bridge DB.

As described above, when the step-down chopper operation is performed, the inverter operation cannot be performed, but when the buck-boost or step-up chopper operation is performed, the chopper operation can be switched while performing the inverter operation. Since the step-down chopper needs to be operated only to suppress the inrush current when the power is turned on, it does not matter so much even if the inverter is not working during that time. Further, by switching the buck-boost or boost chopper operation in the steady state, it is possible to cope with a wide range of power supply voltage and improve the input current distortion.

FIG. 4 is a circuit diagram of the third embodiment of the present invention. The load circuit including the inductor L1, the capacitor C2, and the discharge lamp La, and the configuration of the half-bridge inverter including the transistors Q1 and Q2, the diodes D1 and D2, and the capacitors C3 and C4 are the same as those in the above-described respective embodiments, and therefore, the duplication is repeated. The description will be omitted. Diode D
A series circuit of diodes D3 and D4 is connected in parallel to the series circuit of 1 and D2. A series circuit of the inductor L2 and the switching element SW2 is connected between the connection point of the diodes D1 and D2 and the connection point of the diodes D3 and D4. An AC power supply Vs is connected to both ends of the switching element SW2 via the switching element SW1. The switching elements SW1 and SW2 are bidirectional switching elements and function as switching elements of the step-down chopper.

In this embodiment, the switching element that functions as a boosting or step-up / down chopper is switched depending on the polarity of the power source. Specifically, when the input voltage Vin is positive, the transistor Q1 functions as a chopper switching element, and when the input voltage Vin is negative, the transistor Q2 functions as a chopper switching element. The following will be described only when the input voltage Vin is positive.

First, the step-down chopper operation will be described. Switching elements SW1 and SW2 are inverted and turned on.
Turn off. When the switching element SW1 is on and the switching element SW2 is off, the AC power supply Vs,
Switching element SW1, inductor L2, diode D3, capacitor C1, diode D2, AC power supply Vs
An electric current flows along the path passing through. In addition, the switching element S
When W1 is off and switching element SW2 is on, inductor L2, diode D3, capacitor C
The current flows through the path passing through 1, the diode D2, the switching element SW2, and the inductor L2. In this way, when performing the step-down chopper operation, the current cannot always flow through the diode D2, so that the inverter cannot operate.

Next, the step-up / down chopper operation will be described. The switching element SW1 and the transistor Q1 perform on / off operation in synchronization, and the switching element SW2
Is inverted to perform on / off operation. Switching element S
W1, transistor Q1 is on, switching element SW
When 2 is off, a current flows in a path that passes through the AC power supply Vs, the switching element SW1, the inductor L2, the diode D3, the transistor Q1, and the AC power supply Vs. Further, when the switching element SW1 and the transistor Q1 are off and the switching element SW2 is on, a current flows in a path passing through the inductor L2, the diode D3, the capacitor C1, the diode D2, the switching element SW2, and the inductor L2. When performing this step-up / down chopper operation, the transistors Q1 and Q2 are inverted and turned on.
By turning off, inverter operation is possible.

Next, the step-up chopper operation will be described. When the boost chopper operation is performed, the switching element SW1 is always on and the switching element SW2 is always off. When the transistor Q1 is on,
AC power supply Vs, switching element SW1, inductor L
2, diode D3, transistor Q1, AC power supply Vs
An electric current flows along the path passing through. When the transistor Q1 is off, the AC power supply Vs and the switching element SW
1, inductor L2, diode D3, capacitor C
A current flows through a path that passes through 1, the diode D2, and the AC power supply Vs. Even when the boost chopper operation is performed, the inverter operation can be performed by inverting the transistors Q1 and Q2 to turn them on and off.

When the input voltage Vin is negative, the same operation as described above is performed except that the transistor Q2 is used in place of the transistor Q1, the diode D1 is used in place of the diode D2, and the diode D4 is used in place of the diode D3. . Also in this embodiment, since the inverter operation cannot be performed when the step-down chopper operation is performed, the step-down chopper operation may be performed only when the power is turned on. Thereby, the inrush current can be suppressed. Further, in a steady state, the buck-boost chopper and the boost chopper can be appropriately switched to improve the input current distortion and cope with a wide range of power supply voltages.

[0026]

According to the present invention, a step-up or step-up / step-down chopper circuit which also serves as an inverter circuit for driving a load at a high frequency and a switching element and a step-down chopper circuit in the preceding stage are combined to turn on the switching elements of both circuits.・ By controlling the inrush current when the power is turned on and operating the inverter by providing a control circuit that can operate as a step-down chopper, buck-boost chopper, or step-up chopper by linking the off timing. There is an effect that it is possible to realize an inverter device having a simple configuration capable of improving the input current distortion and coping with a wide range of power supply voltages.

[Brief description of drawings]

FIG. 1 is a block circuit diagram showing a basic configuration of the present invention.

FIG. 2 is a circuit diagram of the first embodiment of the present invention.

FIG. 3 is a circuit diagram of a second embodiment of the present invention.

FIG. 4 is a circuit diagram of a third embodiment of the present invention.

FIG. 5 is a circuit diagram of a conventional inverter device with a chopper.

FIG. 6 is a circuit diagram of a conventional inverter device with a rush current suppressing circuit.

FIG. 7 is a circuit diagram of another inverter device with a conventional inrush current suppression circuit.

[Explanation of symbols]

 1 Step-down chopper circuit 2 Chopper / inverter circuit 3 Load 4 Control circuit

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H05B 41/29 C 9249-3K

Claims (3)

[Claims] 1. An inverter circuit comprising a step-down chopper circuit for rectifying an AC power source and outputting a smooth DC voltage to an electrolytic capacitor via a switching element and an inductor, the inverter circuit converting the smooth DC voltage into a high frequency and supplying the load. The inverter circuit includes a switching element that also serves as a step-up or step-up / step-down chopper, and controls the on / off timings of the switching element of the step-down chopper circuit and the switching element of the inverter circuit to reduce the step-down, step-up / step-down, or step-up. An inverter device having a control circuit capable of operating as any of the chopper circuits of. 2. The inverter device according to claim 1, wherein the inverter is a half-bridge inverter. 3. The inverter device according to claim 2, wherein among the two switching elements of the half-bridge inverter, a switching element that functions as a step-up or step-up / step-down chopper is switched depending on a polarity of a power source.