JPH03296117A - Variable automatic voltage controller - Google Patents

Abstract

PURPOSE:To ensure the high accuracy and high stability regardless of the power factors of a load by outputting the current/voltage via a high frequency filter, a regulator, a current transformer and a high frequency filter and at the same time controlling the output voltage and the switching current through a control part, and outputting these controlled voltage and current to the controller as the PWM signals. CONSTITUTION:The power voltage Vin is outputted to a load 8 set between the output terminals as the output voltage Vout via a high frequency filter 3, a regulator 4, a current transformer 5, and a high frequency filter 6. The voltage Vout and a switching current IL are always detected and controlled by a control part 9 and then outputted to the regulator 4 as the PWM signals. Then the ON time of an AC switch element 4-1 is increased when the voltage Vout is set at a high level or changed to a low level. Meanwhile the ON time of the element 4-1 is shortened when the voltage Vout is set at a low level or changed to a high level, or an excessive output current Iout flows. Thus the voltage is controlled. As a result, the highly accurate and stable output voltage is endured with a compact and inexpensive VV-AVR despite an expected disturbance or accident.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention allows the output voltage supplied to a load from a commercial power source or other AC power source to be arbitrarily variably set from 0 (V) to close to the power supply voltage. This invention relates to a variable automatic voltage regulator (hereinafter abbreviated as VV-AVR) that stabilizes fluctuations in output voltage due to disturbances.

(Prior art) Conventional VV-AVRs include, 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, there is a switching system aiming at compactness and light weight that uses a set of AC switching elements that is a combination of a rectifying diode bridge and a gate turn-off thyristor (hereinafter abbreviated as GT○) as shown in FIG. 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, 7, 7 is an output terminal, 8 is a load,
9 consists of a control section.

The regulator is connected between the power source and the load, as shown in Figure 6 (b
), the AC 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 Vou is
Adjust t and output to the load.

When the output voltage Vout decreases due to disturbance or is set to a high value, the control section compares it with the reference voltage,
Pulse width modulation (hereinafter referred to as PW) created by the comparison signal
A control signal (abbreviated as M) causes the switching of the regulator to have a long on time ton and a short off time toff within the period T, so that the low output voltage Vout is regulated to a set value.

Conversely, when the output voltage Vout increases or when the output voltage Vout is set to a low value, the off time toff of the regulator becomes longer and the on time ton becomes shorter due to the function of the control section, and the higher output voltage vOut becomes lower. 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 source to the load is turned off by the regulator for a short time as shown in FIG. 6(b), the voltage between the anode and cathode of the switching element GT○ is
Absorbs the excessive back electromotive force VL generated by the small inductance L of a resistive load such as a nichrome wire and the non-negligible inductance L present on the power supply side and wiring, such as Vak in C). Therefore, a snubber circuit and a surge absorption element are required to protect the GTO from damage.

For example, when inductance L = 10 (μH) output current Iout-10 (A) turn-off time tf = 1.0 (μ5ee) frequency f = 20 <flz), back electromotive force VL and snubber circuit loss Pl
What about oss? VL=L-△Iout/1f=100
(V) Ploss-0,5LIout"f = 1.0
(W) becomes.

In the case of the above example, since the inductance is small, 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 load consisting of the windings and iron core of a motor etc. has extremely large inductance compared to resistive loads.

For example, inductance L=10 (mH>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)
What about oss? Vl,=L-ΔIout/1f=l
O(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 boat fishing 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.

(4) When excessive current flows due to a load short-circuit accident or load rush current, semiconductor elements such as GTO cannot be protected because there is no protection function.

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

The purpose of the present invention is to eliminate or significantly improve the above-mentioned problems, stabilize the output voltage with high precision and protect the device even in the event of anticipated disturbances or accidents, and set an arbitrary output voltage to the load. The object of the present invention is to provide a VV-AVR that is compact, lightweight, has good efficiency and power factor, has little waveform distortion of output voltage, has fast response speed, is highly reliable, and is inexpensive.

(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 6 is connected to the output side of the regulator 4 via the primary side of a current transformer 5.

A load 8 is connected to the output side of the high frequency filter 6 via output terminals 7-1, 7-2.

The input side of the regulator 4 is the two ends of two non-directional AC switching elements 4 (, 4-2) connected in series, which perform 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 AC switching elements 4-1, 4-2 and one of the input sides of the regulator.

Control for detecting an error between the output voltage and a set reference voltage and an excess of a protection voltage of the secondary side voltage of the current transformer 5 and outputting a PWM signal to the AC switch element 4-1, 4-2. It is formed by connecting parts 9.

(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, the high frequency filter 3, the regulator 4. Current transformer5. It is output as an output voltage Vout to the load between the output terminals via the high frequency filter 6.

The output voltage Vout and the switching current IL are constantly detected and controlled by the control unit 9 and output to the regulator as a PWM control signal.

When the output voltage Vout is set to a high value or fluctuates to a low value, an AC switching element 4 connects the power supply side and the load side and outputs the switching operation of the regulator 4 according to the PWM control signal. AC switching element 4- which increases the on-time of -1, cuts off the load side from the power supply side, and short-circuits the input side of the high frequency filter 6 to commutate the current.
The on-time of 2 is shortened, and the switching voltage Vsw is a low output voltage V.

ut is increased and adjusted as appropriate, smoothed by a high frequency filter 6, and output to the load between the output terminals.

When the output voltage Vout is set to a low value or fluctuates to a high value, or when the output current I is excessive.

When ut is about to flow, the switching operation of the regulator 4 based on the PWM control signal is shortened on the ON time of the AC switching element 4-1 that connects the power supply side and the load side and goes to the output. The on-time of the AC switching element 4-2 that commutates the current IL is increased by cutting off the load side and short-circuiting the input side of the high-frequency filter 6, and the switching voltage Vsw is adjusted by appropriately lowering the high output voltage Vout. or limit the output current Iout that tends to flow excessively.

The switching operation of the regulator 4 is such that when the alternating current switching element 4-1 is off, the alternating current switching element 4-2, which commutates the current IL on the load side, is on, and what kind of inductance is present on the load side. It acts to prevent excessive back electromotive force from being generated.

(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 the power supply between 2 and 2, and also connect the input terminal 2-1. Similarly, a load 8 is connected between the output terminals 7-1 and 7-2 to supply power 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.

Adjuster 4> The regulator 4 has an AC switching element 4-1 and an AC switching element 4-2 that operate in opposition to each other connected in series to the output side of the high frequency filter 3, and both ends thereof are connected as the input side of the regulator 4. Both ends of the AC switching element 4-2 are connected to the output side of the regulator 4, field effect transistors (hereinafter referred to as FETs) connected in series with opposite polarities are used as the AC switching element, and the PWM control signals A2. A switching operation is performed according to A3.

Current transformer 5> The current transformer 5 has its primary side connected so as to detect the switching current IL flowing from the output side of the regulator 4 to the input side of the high frequency filter 6, and detects the detection voltage Va of the secondary winding.
t is input to the comparison amplification section 9-3 of the control section 9.

High frequency filter 6> The high frequency filter 6 has a choke coil 6 between the output side of the regulator 4 and each terminal of the current transformer.
-1 and a capacitor 6-2 connected in series are connected as input sides of the high frequency filter 6, and both ends of the capacitor 6-2 are connected as output sides of the high frequency filter 6. The waveform of the switching voltage Vsw by the regulator 4 is smoothed into the original sine wave.

Control unit 9> The control unit 9 detects the output voltage Vout from between the output terminals 7-1, 7-2, and outputs the detection voltage Vo of the detection unit 9-1 and the reference voltage Vref of the switching IC unit 9-5.
is input into the output voltage setting unit 10 and the set reference voltage Vs is input into the comparison and amplification unit 9-2 to obtain the calculated voltage Vopl, the voltage Vct detected by the current transformer 5, and the switching IC unit 9-5. A calculation output Vop2 obtained by manually applying the reference voltage Vref to the comparison amplifier section 9-3 is passed through an AND circuit 9-4 to create a voltage Vop, and the sawtooth wave voltage Vtr is compared with the voltage Vop in the switching IC section 9-5. And here the voltage V
The height of the op value is the PWM signal source, and the signal A is input to the pulse shaping network (hereinafter abbreviated as PFN) 9-6 to create the signal A1 which is an inversion of the signal A, and the rise time of the signal A and Al is Slightly delayed PWM control signal A2.
A3 is inputted between the gate and source of the FET of the AC switching element 4-1, 4-2 via the insulation/drive section 9-7 to set and stabilize the output voltage Vout.

1 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. Current transformer5. The output voltage V is applied to the load between the output terminals via the high frequency filter 6.

When applied as ut, the output current is 1゜u depending on the load power factor.
A current of t flows.

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 6 and the current IL flowing through the choke coil 6-1 of the high frequency filter 6 are as shown in FIG. 2(b).
Figures 2 (C) and (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, as shown in FIG. 2(e), the AC switching element 4-1 is on, the AC switching element 4-2 is off, and the power supply voltage V
in passes through the AC switching element 4-1 and is applied to the input side of the high-frequency filter 6 to become the voltage Vsw, which causes the current IL to flow through the choke coil 6-1, increasing its value by 2, and the voltage in the AC switching element 4. The increase in current La flowing through -1 is supplied from capacitor 3-2 and choke coil 6-1
is stored as energy.

In the interval t2=t3, as shown in FIG. is cut off by the AC switching element 4-1, the input side of the high frequency filter 6 is short-circuited by the AC switching element 4-2, the current IL is commutated and its value decreases, and the current I flowing through the AC switching element 4-2
The decrease in f is released to the load as energy stored in the choke coil 6-1.

In the section t3 to t4, AC switching elements 4-1 and 4-2 are again used.
are mutually inverted, resulting in the same state as in the section 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 6, and the high frequency filter 6
The output voltage Vout smoothed by passing through can be expressed by the following equation.

Vout= (ton/T) -Vin In other words, the output voltage Vop of the AND circuit of the control section 9 is determined as shown in FIG. 2(C).
The on time t within the cycle of 1 hour.

By continuously variable control of n from 0 to period T, the output voltage Vout can be adjusted from 0 (v) to the power supply voltage Vin.

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

<When the output voltage Vout is set to a high value or fluctuates to a low value> The output detection voltage Vo, which is proportional to the output voltage Vout, becomes lower than the reference setting voltage Vs, and as shown in Fig. 3(b), the comparison The output voltage Vop of the AND circuit, which is equal to the operation voltage Vopl of the amplification section 9-2, is between the minimum value and the peak value of the sawtooth wave voltage Vtr, and changes toward the higher side, and the switching IC section 9-5 Due to the functions of the comparator circuit, PFN9-6, and insulation/drive section, the switching voltage Vsw in FIG. 3(C) has a long on time ton and a long off time to.
ff becomes shorter, and the low output voltage Vout is adjusted by increasing it appropriately.

When the output voltage Vout is set to a low value or fluctuates to a high value> The output detection voltage Vo becomes higher than the reference setting voltage Vs, and as shown in FIG. 3(b), the voltage Vop becomes a sawtooth wave voltage. Vtr
The switching voltage Vsw in FIG. 3(C) has a short on time ton and a short off time toff.
becomes longer, and the high output voltage Vout is adjusted by lowering it appropriately.

<When an excessive output current is about to flow> During normal operation, a choke coil current rL proportional to the output current Iout is applied to the primary side of the current transformer 5 up to just before the part 2 in FIG. 3(a). is flowing, and the detected voltage Vct proportional to the current (current) L generated on the secondary side of the current transformer 5 is input to the comparison amplifier section 9-3, and the reference voltage Vref in the switching IC section 9-5 is inputted to the comparison amplifier section 9-3.
The voltage Vop2 of the comparator amplifier 9-3 is a sawtooth wave voltage. Waiting at a value higher than the peak value of Vtr,
Output voltage Vo of AND circuit with low value voltage signal priority function
p is determined by the calculation voltage Vop1 of the comparison amplifier section 9-2,
Continue normal operation.

If an excessive current IL is to flow through the choke coil 6-1 and the primary side of the current transformer 5, it will be expressed as shown in FIG. Figure 3 (
b) and (C), the detection voltage Vct exceeds the protection level Vp or Vp as shown in sub-element 2 and subsequent parts in FIG. becomes lower than the calculation voltage Vopl of the amplifier section 9-2, and AN
The output voltage Vop of the D circuit is switched to the voltage Vop2,
The switching voltage Vsw in FIG. 3(C) is the on-time to
As n becomes shorter, off-time toff becomes longer, and excessive output current Iout is instantly limited.

All parts of the main circuit are protected from excessive current and automatically return to normal operation once the cause is removed.

<Other Embodiments> (1) The configuration of the main circuit is shown in FIG. 1 as an example, but as shown in FIG. When the autotransformer 11 is inserted, the output voltage Vout can be higher or lower than the power supply voltage Vin, and the insulation type transformer can also 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 further connecting one set of AC switching elements 4-3, 4-4 between the choke coil 6-1 and the capacitor 6-2 of the high-frequency filter 6 as shown in FIG. 4(b), the output voltage Vout can be increased. In the setting range lower than the power supply voltage Vin, the AC switch element 4-3 is turned off, and the AC switch element 4-4 is left on, and the AC switch element 4-1 is turned off in the same way as in the method shown in Fig. 1.
．． 4-2 is operated in a contradictory manner, and when it is desired to make the output voltage Vout higher than the power supply voltage Vin, the AC switching element 4-1 is turned on and the AC switching element 4-2 is left turned off. PW that contradicts 3°4-4
In the M control operation, the output voltage Vout can be boosted and adjusted by the back electromotive force of the choke coil 6-1.

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 as shown in Figure 1 as an example.
By further connecting one set of AC switching elements 4-3, 4-4 to the regulator 4 as shown in FIG. 4(C), when the output voltage Vout is output in the same phase as the power supply voltage Vin, Switching element 4-3 is turned off and switching element 4-4 is left on, and the output is adjusted using opposite PWM control operations on AC switching elements 4-1 and 4-2 in the same manner as in the method shown in Fig. 1. When the output voltage Vout outputs a phase opposite to the power supply voltage Vin, the AC switch element 4-1 is turned on;
-2 remains off, and in the same way, AC switch element 4-
If 3.4-4 is adjusted by contradictory PWM control operation, the output voltage Vout will continuously change from the power supply voltage Vin value to 0.
It is possible to adjust up to the voltage value of the opposite phase of the power supply voltage Vin via (■).

(4) The configuration of the main circuit is shown in FIG. 1 as an example.
As shown in FIG. 4(d), the AC switching element 4- of the regulator 4
2 and the choke coil 6-1 of the high-frequency filter 6, and adjust the output using opposite PWM control operations on the AC switching elements 4-1 and 4-2 in the same way as in the method shown in Fig. 1. Then, the output voltage Vout can be output in the opposite phase to the power supply voltage Vin.

(5) Install a no-fuse breaker on the input terminal 2-1.2-2 side and the output terminal 7-1.7-2 side of the main circuit for turning on/off the power supply and load and for double protection from excessive current. Also, depending on the usage environment of this VV-AVR, a noise filter or a noise cut transformer may be connected to reduce the influence of conduction noise.

(6) Each AC switch element of the regulator 4 is F in FIG.
An example of an AC switch element in which ETs are connected in series with opposite polarities is shown in FIG. 5(a).

As shown in (b), the FET is replaced with a semiconductor element having a self-turn-off function, such as a transistor or a GTO with a high-speed diode connected in parallel in the opposite direction to the current direction of the element, or an AC switching element; Figure (c
), (d), and (e), connect the drain and source of F9 ET, the collector and emitter of a transistor, or the anode and cathode of GTO between the positive and negative terminals of the rectifying bridge of the high-speed diode, respectively, and perform the rectification. A structure in which an AC switch element is used between the AC terminals of the bridge has a similar function.

(7) When the AC switching elements 4-1 and 4-2 or 4-3 and 4-4 of the regulator 4 are reversed, the control unit 9 prevents short circuits caused by the upper and lower elements due to the switching characteristics of each element. A dead time is provided in P F N 9-6 to slightly delay the turn-on of each AC switching element, and a snubber circuit that absorbs the surge voltage generated between the elements at this time is connected in parallel to each AC switching element. You can also do it.

(8) Although the current transformer 5 is used as an example of the current detector for detecting the choke coil current IL, the same function can be achieved even if a resistor or a Hall element is applied.

(9) In the signals input from the detection unit 9-1 of the control unit 9 and the output voltage setting unit 10 to the comparison amplification unit 9-2, the DC mode method integrates the absolute value of the output voltage Vout, and outputs a DC sampled and held at 0. This is a method of inputting the voltage Vo and the DC set reference voltage Vs.The AC mode method involves inputting an AC output detection voltage ■0 and an AC reference voltage synchronized with the power supply voltage Vin. The case of mode method is described below.

(10) The VV-AVR of the present invention is a device that detects the output voltage and has constant output voltage characteristics, but it can also be a device that similarly detects the output current and has constant output current characteristics. It is also possible to create a device that has both characteristics, or a device that has constant output power characteristics by calculating the detected voltage and current.

(11) When the VV-AVR of the present invention starts operating or recovers from an instantaneous power outage, the reference voltage Vs is instantly lowered and then raised to the steady-state value Vs over a certain period of time, thereby increasing the output voltage Vo.
ut changes from a low voltage to a steady value Vou according to the reference voltage Vs.
It is also possible to smoothly raise the temperature up to t.

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

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

(1) Since the regulator is equipped with an AC switching element for current commutation, and a current loop is always established, it can be used with loads of any power factor, and the loss in the snubber circuit can be extremely small.

(2) The waveform switched by the regulator is reshaped into the original sine wave by the high frequency filter 6, so it can be used for any type of load.

(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) High reliability can be obtained in the use of semiconductor devices because the protection action is instantaneously activated against excessive currents and surge voltages such as load short-circuit accidents that are applied to the elements of AC switching devices.

(5) Continuously variable PWM control allows 0 (V
) to the power supply voltage Vin, it can be set to any output voltage.

(6) Continuously variable PWM control allows high accuracy (±
1.0 to ±0.1%) is obtained.

(7) PWM control is performed at an extremely high frequency (>20 Gtz) compared to the power supply frequency (50/60 Hz), so even if there is a disturbance, a high-speed response (200 to 1 m5ec) can be obtained, so the output voltage can be reduced. The impact can be minimized.

(8) 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 175 to 1/2).

(9) 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.

3

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the VV-AVR related to the present invention, and FIGS. 2 and 3 are VV-AVH related to the present invention.
Figures 4 and 5 are partial circuit diagrams showing other embodiments of the VV-AVR according to the present invention, and Figure 6 is the circuit diagram and waveforms of a conventional VV-AVR. It is a figure. 1... Power supply, 2... Input terminal, 3... High frequency filter, 4... Regulator, 5... Current transformer, 6... High frequency filter, 7... Output terminal, 8 ...Load, 9
...control section, 10...output voltage setting section, 11
...Auto transformer. 4

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 regulator to the output side of the regulator via the primary side of the current transformer. The input side of a second-stage high-frequency filter is connected, and a load is connected to the output side of this second-stage high-frequency filter via an output terminal, and the input side of the regulator performs on-off switching multiple times during an AC half cycle. Two non-directional AC switching elements are connected in series at both ends, and the output side of the regulator is between the series connection point of the AC switching elements and one of the input sides of the regulator. ,
The variable voltage converter is connected to a control unit that detects an error between the output voltage and the set reference voltage and an excess of the protection voltage of the secondary side voltage of the current transformer and outputs a pulse width modulation signal. Type automatic voltage regulator.