JPH04207970A - Voltage regulator - Google Patents

Abstract

PURPOSE:To realize variable setting of an arbitrary sine wave output voltage by constituting a voltage regulator of a prestage high frequency filter, a regulator, a high frequency filter, a load and a control section. CONSTITUTION:A power supply is connected between input terminals 2-1, 2-2 and power is fed through a high frequency filter 3, a regulator 4 and a high frequency filter 5 to a load 7. The high frequency filter 3 functions such that the switching operation of the regulator 4 does not interfere with the power supply side. The regulator 4 performs switching operation according to PWM control signals A2, A3. The high frequency filter 5 smoothes a switching voltage Vsw fed from the regulator 4 into the original sine wave. A control section 8 performs continuous variable control of ON interval between 0 to a period T based on a set reference voltage Vs thus regulating the output voltage Vout between 0 to the power supply voltage Vin.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention allows the output voltage of a sine wave supplied to a load from a commercial power source or other AC power source to be variably set from o(V) to close to the power supply voltage. This relates to a voltage regulator (hereinafter abbreviated as VR).

(Prior Art) Conventional VR includes, for example, a system that combines a sliding transformer and a motor, and a system that combines a thyristor phase control unit and a filter, both of which are heavy and large in size.

Recently, some switching systems aiming at compactness and light weight use a set of bidirectional switching elements that combine a rectifier diode bridge and a gate turn-off thyristor (hereinafter abbreviated as GT○) as shown in Figure 6(a). .

To explain with reference to Fig. 6(a), 1 is a power supply, 2゜2 is an input terminal, 4 is a regulator, 6, 6 is an output terminal, 7 is a load,
8 is a control section, and q is an output voltage setting device.

The regulator is connected between the power source and the load, as shown in Figure 6 (b
), the bidirectional switching element of the regulator is turned on and off several times during an AC half cycle of the power supply voltage Vin, and the output voltage Vo is
Adjust ut and output to the load.

When the output voltage Vout is set to a high value, the control section generates pulse width modulation (hereinafter referred to as PW) based on the setting signal.
According to the control signal (abbreviated as M), the switching of the regulator is such that the on time ton within the period T is long and the off time toff is short, so that the low output voltage Vout can be adjusted to the set value.

Conversely, when the output voltage Vout is set to a low value, the switching of the regulator is controlled by the off-time tof due to the function of the control section.
f is long, on-time ton is short, and high output voltage V
Out can be adjusted to the set value.

(Problem to be solved by the invention) The circuit shown in FIG. 6(a) has the following problems.

(1) When the current Iout flowing from the power supply to the load is turned off by the regulator in a short time as shown in Fig. 6(b), a resistive load such as a nichrome wire is placed between the anode and cathode of the switching element GT○. The small value of inductance that exists on the power supply side and the non-negligible inductance L that exists on the power supply side and the wiring generates an excessive back electromotive force VL, so a voltage such as Vak in Figure 6 (c) is applied. do. A snubber circuit or a surge absorbing element is required to absorb such an excessive back electromotive force VL and protect GT◯ from damage.

For example, inductance and 10 (μH) output current
Iout=10 (A) Turn-off time tf=1.0 (μ5ee) Frequency f=20 (KH2), back electromotive force VL and snubber circuit loss Pl
What about oss? VL=L-ΔIout/1f=100
(V)P1oss=0.5LIout2f=1.0(
W) becomes.

In the case of the above example, since the load is a resistive load such as a nichrome wire, the inductance is small, so the back electromotive force and the loss of the snubber circuit can be countered with a relatively small snubber circuit or surge voltage suppressor, but the winding of the motor etc. In the case of a load consisting of a steel core and an iron core, the inductance is extremely large.

For example, □, inductance L=10 (n+H) output current Iout=10 (A) turn-off time tf=10 (μ5ee) frequency
Back electromotive force VL and snubber circuit loss Pl when f = 2 (KHz)
oss is '7 VL=L-ΔIout/1f=1
0 (KV)P1oss=0.5LIout2f=1
．． 0 (KW).

It can be seen that the back electromotive force and the loss of the snubber circuit are extremely large, and the efficiency of the device is extremely low, so that it cannot be put to practical use unless other methods are used.

In other words, the method shown in FIG. 6 can only be used for resistive loads, and its versatility for general loads is extremely limited.

(2) When the regulator performs a switching operation, the current on the power supply side changes directly and sharply, causing distortion of the power supply waveform and adverse effects on the outside as conduction noise.

(3) When the regulator performs a switching operation, the voltage and current applied to the load directly change sharply, which limits the load that can be used and also causes negative effects such as noise on the outside.

Users have been requesting smaller, lighter weight, and higher performance static VRs, but it has been difficult to apply and develop circuit systems and devices that are suitable for the various AC power conditions and loads. , until now it has not been possible to commercialize it.

The purpose of the present invention is to eliminate or significantly improve the above-mentioned problems, to smoothly commutate energy during switching, to easily and variably set an arbitrary sine wave output voltage to a load, and to be small and lightweight. The object of the present invention is to provide a highly reliable and low-cost VR with good efficiency and power factor, little waveform distortion of output voltage.

(Means for Solving the Problems) The means of the present invention to achieve the above object will be explained with reference to FIG.

The input side of the pre-stage high frequency filter 3 is connected between the AC power input terminals 2-1 and 2-2.

The input side of the regulator 4 is connected to the output side of the high frequency filter 3.

The input side of a high frequency filter 5 is connected to the output side of the regulator 4.

A load 7 is connected to the output side of the high frequency filter 5 via output terminals 6-1, 6-2.

The input side of the regulator 4 has two bidirectional switching elements 4-1 and 4-2 connected in series, each of which performs on-off switching multiple times during an AC half cycle.

The output side of the regulator 4 is between the series connection point of the bidirectional switch elements 4-1, 4-2 and one of the input sides of the regulator.

A control unit 8 that outputs a PWM signal to obtain an arbitrary sine wave output voltage to the bidirectional switch element 4-1, 4-2.
It is made by connecting.

(effect) The operation of the above means will be explained with reference to FIG. 1.2.3.

The power supply voltage Vin is applied between the input terminals 2-1 and 2-2 to the high frequency filter 3. Adjuster 4. It is output as an output voltage Vout via the high frequency filter 5 to the load 7 between the output terminals 6-1, 6-2. The PWM control signal of the control unit 8 is a sine wave.
By always switching the regulator 4 at a constant ratio with respect to the period, the sine wave output voltage Vo is the same as the input sine wave.
It can be output as ut.

When the output voltage Vout is set to a high value, the PWM
The switching operation of the regulator 4 according to the control signal is controlled by the on-time ton=tl-t of the switching element 4-1 which connects the power supply side and the load side and outputs it as shown in FIG. 2(e).
2 is lengthened, and then, as shown in FIG. 2(f), the on time tOff of the switch element 4-2 is cut off from the power supply side to the load side, and the input side of the high frequency filter 6 is short-circuited to commutate the current IL.
=t2-t3 is shortened, the switching voltage Vsw is adjusted by increasing the low output voltage Vout, smoothed by the high frequency filter 6, and output to the load between the output terminals.

When the output voltage Vout is set to a low value, the PWM
The switching operation of the regulator 4 according to the control signal is performed by shortening the on-time ton of the switching element 4-1 and lengthening the on-time of the switching element 4-2, so that the switching voltage V
sw is adjusted by lowering the high output voltage Vout.

The switching operation of the regulator 4 is such that when the switching element 4-1 is turned off, the AC switching element 4-2, which commutates the current IL on the load side, is turned on, and what kind of inductance is present on the load side. Even when the load is off, an excessive back electromotive force is not generated, and this energy is smoothly commutated to the load.

(Example) Hereinafter, the present invention will be described in detail with reference to the drawings.

<Main circuit> As shown in Figure 1, input terminal 2-1゜2-
Connect a power supply between input terminals 2-1. A load 8 is connected between the output terminals 6-1 and 6-2 to supply power from the source to the load.

High frequency filter 3> High frequency filter 3 is input terminal 2
-1. Choke coil 3-1 and capacitor 3 between 2-2
-2 connected in series are connected as the input side of the high frequency filter 3, and both ends of the capacitor 3-2 are connected as the output side of the high frequency filter 3. It acts so that the influence of the switching operation by the regulator 4 and the influence from the power supply side do not interfere with each other.

Regulator 4> The regulator 4 connects the output side of the high-frequency filter 3 with a switch element 4-1 and a switch element 4-2 that operates in opposition to each other in series, and connects both ends of the switch element 4-1 and the switch element 4-2, which operate in opposition to each other, as the input side of the regulator 4. Both ends of the element 4-2 are the output sides of the regulator 4, field effect transistors (hereinafter abbreviated as FETs) connected in series with opposite polarities are used as a bidirectional switch element, and the PWM control signals A2. A switching operation is performed according to A3.

High frequency filter 5> The high frequency filter 5 has a choke coil 5-1 and a capacitor 5 between the output side terminals of the regulator 4.
-2 connected in series are connected as input sides of the high frequency filter 5, and both ends of the capacitor 5-2 are connected as the output sides of the high frequency filter 5. Switching voltage V by regulator 4
Smooth the waveform of sw to the original sine wave.

<Control unit 9> The control unit 9 compares the sawtooth wave voltage Vtr and the output voltage setting reference voltage Vs in the switching IC unit 8-1 as shown in FIGS. 3(a) and 3(b), and here the voltage Vs The high and low values become the PWM signal A, and the signal A is input to a pulse shaping circuit network (hereinafter abbreviated as PFN) 8-2 to create a signal A1 which is an inversion of the signal A.

PWM control signal A2. with a slightly delayed rise time of A1. An arbitrary sine wave output voltage Vout is set by inputting A3 between the gate and source of the FET of the switching element 4-1, 4-2 via the insulation/drive section 8-3.

Operation explanation> Next, the operation of the above embodiment will be explained.

The power supply voltage Vin as shown in FIG. 2(a) is applied between the input terminals of the high frequency filter 3. Adjuster 4. When the output voltage Vout is applied to the load 7 between the output terminals via the high frequency filter 5, a current similar to the output current rout flows through the output terminals depending on the load power factor.

When the power supply voltage Vin passes through the high frequency filter 3 and is switched by the regulator 4, the switching voltage Vsw applied to the input side of the high frequency filter 5 and the current IL flowing through the choke coil 5-1 of the high frequency filter 5 are as shown in FIG. 2(b).
Figures 2(c) and 2(d) are enlarged views of the molecule 1 for ease of understanding, and Figures 2(e) and 2(e) represent the operating state of the main circuit. (f).

In the interval t1 to t2 of FIG. 2(C), as shown in FIG. 2(e), the switching element 4-1 is on and the switching element 4-2 is off,
The power supply voltage Vin is applied to the input side of the high frequency filter 5 through the switch element 4-1, and the value increases by causing the current IL to flow through the choke coil 5-1 as shown in FIG. 2(d). , an increase in the current Ia flowing through the switch element 4-1 is mainly supplied from the capacitor 3-2 and stored as energy in the choke coil 5-1.

Similarly, in the interval t2 to t3, as shown in FIG. 2(f), the on and off states of the switch elements 4-1 and 4-2 are reversed, so that the switch elements 4-1 is off and the switch element 4-2 is on. , power supply voltage V
in is cut off by the switch element 4-1, the input side of the high frequency filter 6 is short-circuited by the switch element 4-2, the current IL is commutated and its value decreases, and the decrease in the current If flowing through the switch element 4-2 is The energy stored in the choke coil 5-1 is released to the load.

Similarly, in the section t3 to t4, switch elements 4-1 and 4
-2 are inverted to each other, resulting in the same state as the interval t1 to t2.

In this way, the switching voltage Vsw as shown in FIG. 2(C) obtained by PWM switching the power supply voltage Vin is applied to the input side of the high frequency filter 5, and the high frequency filter
The output voltage Vout smoothed by passing through can be expressed by the following equation.

Vout= (ton/T) -Vin That is, by continuously variable control of the on time ton within the period T time in FIG. 2(C) from 0 to the period T using the set reference voltage Vs of the control unit 8. The output voltage Vout can be adjusted from 0 (■) to the power supply voltage Vin.

Here, on-time ton=t2-tl=t4-t3 period T=t3-tl=t4-t2 Other detailed circuit constants are omitted.

When you want to set the output voltage Vout to a high value> As shown in Fig. 3(a), the reference setting voltage Vs corresponding to the desired output voltage Vout is between the minimum value and the peak value of the sawtooth wave voltage Vtr. The switching voltage Vsw shown in FIG. 3(b) has a long on-time ton' due to the functions of the comparator circuit in the switching IC section 8-1, the PFN 9-6, and the insulation/drive section. , the off-time toff becomes shorter, and the low output voltage Vout can be adjusted by increasing it appropriately.

<When you want to set the output voltage Vout to a low value> Conversely, the reference setting voltage Vs is changed to the lower side of the sawtooth wave voltage Vtr, and the switching voltage Vsw shown in FIG. 3(b) has a short on time ton. The off time toff becomes longer,
Adjust by lowering the high output voltage Vout as appropriate.

<Other Embodiments> (1) The configuration of the main circuit is shown in FIG. 1 as an example, but as shown in FIG. If the autotransformer 10 is inserted, a large output current can be obtained with the output voltage Vout being higher or lower than the power supply voltage Vin, and an isolation type transformer can isolate the power supply side and the load side. .

(2) The configuration of the main circuit is shown in FIG. 1 as an example.
By connecting two more bidirectional switching elements 4-3 and 4-4 between the choke coil 5-1 and the capacitor 5-2 of the high-frequency filter 5 as shown in FIG. 4(b),
In the setting range where the output voltage Vout is lower than the power supply voltage Vin, the bidirectional switching element 4-1.4- is turned off, and the bidirectional switching element 4-4 is left on, in the same manner as in the method shown in FIG. If you want to adjust the output by performing opposite switching operations, and to make the output voltage Vout higher than the power supply voltage Vin, the bidirectional switching element 4-1 is turned on and the bidirectional switching element 4-2 is left off. 4
-3. The output voltage Vout can be boosted and adjusted by the back electromotive force of the choke coil 5-1 by the PWM control operation that is opposite to the switching of 4-4.

In this method, for boosting voltage using a transformer in the above section (1),
Since the voltage can be stepped up without using a transformer, it is possible to further reduce the size and weight.

(3) The configuration of the main circuit is shown in FIG. 1 as an example.
When the output voltage Vout is output in the same phase as the power supply voltage Vin by further connecting two bidirectional switching elements 4-3 and 4-4 to the regulator 4 as shown in FIG. 4(C), A PWM method in which the switching of the bidirectional switching elements 4-1 and 4-2 is reversed in the same way as the method shown in Fig. 1, with the bidirectional switching element 4-3 turned off and the bidirectional switching element 4-4 kept on.
The output is adjusted by control operation, and when the output voltage Vout is output in the opposite phase to the power supply voltage Vin, the switch element 4
-1 is turned on and switch 4-2 is left off, and the switching of switch elements 4-3 and 4-4 is similarly reversed.
When adjusted by the M control operation, the output voltage Vout can be continuously adjusted from the power supply voltage Vin value through 0 (v) to a voltage value of the opposite phase of the power supply voltage Vin.

(4) The configuration of the main circuit is shown in FIG. 1 as an example.
As shown in FIG. 4(d), the connection positions of the bidirectional switching element 4-2 of the regulator 4 and the choke coil 5-1 of the high-frequency filter 5 are exchanged with each other, and the switching element is 4-1. When the output is adjusted by PWM control operation that contradicts the switching in 4-2, the output voltage Vo
ut can output an output having a phase opposite to that of the power supply voltage Vin. In this method, a negative phase output can be obtained without adding the transformer or switch element described in items (1) and (3) above.

(5) A no-fuse breaker is installed on the input terminal 2-1.2-2 side and the output terminal 6-1.6-2 side of the main circuit to turn on/off the power supply and load and to protect against excessive current. Depending on the usage environment of this VR, a noise filter or a noise cut transformer may be connected to reduce the influence of conduction noise.

(6) Each switch element of the regulator 4 is the FET shown in FIG.
In one embodiment, a bidirectional switch element is obtained by connecting the two in series with opposite polarities, as shown in FIG. 5(a).

As shown in (b), semiconductor elements with a self-turn-off function are used instead of FETs, such as transistors, GBTs, and GBTs.
T○, an AC switching element in which SIT is replaced with a high-speed diode connected in parallel in the direction opposite to the current direction of the element, or FIGS. 5(C) and (d).

As shown in (e), connect the drain and source of an FET, the collector and emitter of a transistor, or the anode and cathode of a GT○ between the positive and negative terminals of the rectifier bridge of the high-speed diode, respectively, and connect the AC terminals of the rectifier bridge. An AC switch element also has a similar function.

(7) bidirectional switching elements 4 to 1 and 4-2 of regulator 4;
Or, when 4-3 and 4-4 are reversed, the dead time is set to slightly delay the turn-on of each bidirectional switching element using the PFN 9-6 of the control unit 9 in order to prevent short circuits caused by the upper and lower elements due to the switching characteristics of each element. It is also possible to connect a snubber circuit in parallel to each switch element to absorb the surge voltage generated between the elements at this time.

(8) When the VR of the present invention starts operating or recovers from a momentary power outage, the output voltage setting reference voltage Vs is instantly lowered and then raised to the steady-state value Vs over a certain period of time.
out changes from a low voltage to a steady value Vo according to the reference voltage Vs.
It is also possible to smoothly raise it to ut.

(9) The operating power for the control unit 8 can be supplied by providing a power transformer or a switching DC power supply.

(Effects of the Invention) Since the present invention is constructed as described above, it has the following effects.

(1) Bidirectional switch element 4- for current commutation in regulator 4
2, a current loop is always established, so it can be used with loads of any power factor, and it also has a snubber.
Circuit loss can also be extremely reduced.

(2) The waveform switched by the regulator is passed through the high frequency filter 5. It can be used for any kind of load because it is smoothed back to the original sine wave by .

(3) Since the high frequency current when switched by the regulator is supplied from the high frequency filter 3 on the power supply side, the adverse effects of waveform distortion, conduction noise, etc. on the power supply side can be minimized to a minimum.

(4) Continuously variable PWM control allows the output voltage to be set to any desired value, such as from 0 to the power supply voltage Vin.

(5) Since the main components constituting the main circuit are only small high-frequency components and semiconductor components, the entire device can be made small and lightweight (volume ratio 115 to 1/2).

(6) The frequency of the voltage waveform switched by the regulator is in the ultrasonic band, so the noise is extremely small.

It is understood that because of the above effects, the present invention is extremely superior compared to other systems.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of VR related to the present invention,
Figures 2 and 3 are waveform diagrams and main circuit diagrams of VR related to the present invention, and Figures 4 and 5 are VR waveforms and main circuit diagrams related to the present invention.
FIG. 6 is a partial circuit diagram showing another embodiment of R, and is a circuit diagram and waveform diagram of a conventional VR. DESCRIPTION OF SYMBOLS 1... Power supply, 2... Input terminal, 3... High frequency filter, 4... Adjuster, 5... High frequency filter, 6...
...Output terminal, 7...Load, 8...Control unit, 9...
・Output voltage setting device, 10...Auto transformer. Figure 2 35! ! Figure 5(a)(b)

Claims (1)

[Claims] 1 Connect the input side of the front-stage high-frequency filter between the AC power input terminals, connect the input side of the regulator to the output side of this front-stage high-frequency filter, and connect the input side of the rear-stage high-frequency filter to the output side of this regulator. , a load is connected to the output side of this latter-stage high-frequency filter via an output terminal, and the input side of the regulator includes two bidirectional AC switching elements that perform on-off switching multiple times in a reciprocal manner during an AC half cycle. are both ends connected in series, and the output side of the regulator is between the series connection point of this bidirectional switch element and one of the input sides of the regulator, and an arbitrary sine wave output voltage is applied to the bidirectional switch element. A voltage regulator characterized in that it is connected to a control section that outputs a pulse width modulation signal to obtain a pulse width modulation signal.