JPH0526958Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to an automatic voltage regulator used in an alternating current generator driven by an internal combustion engine or the like.

(Prior art and its problems) Conventionally, as an automatic voltage regulator that controls the output voltage of an alternator such as a portable engine generator to a substantially constant value regardless of load fluctuations, for example, there is an automatic voltage regulator shown in FIG. something is known.

In FIG. 3, symbol G is a synchronous generator driven by an engine, and on the rotor side of this generator G, a rotor core 1 is attached to the crankshaft of the internal combustion engine directly or through a suitable coupling.
is arranged, and the field winding 2 is wound around it. Furthermore, an excitation winding 3 and an output winding 4 are provided on the stator side, and a part of the output winding 4 serves as a detection winding 4a.

A conventional automatic voltage regulator for such a generator G is configured as follows. That is, this automatic voltage regulator u includes a first rectifying and smoothing circuit 5,
It is composed of a second rectifying and smoothing circuit 6, a detection circuit 7, and a control circuit 8.

The first rectifying and smoothing circuit 5 includes a full-wave rectifier 51 that rectifies the output voltage of the excitation winding 3;
It consists of a capacitor _C1 that smoothes the rectified output of
A field current supply source that sends out a field current If to the output line 9 is formed.

The second rectifying and smoothing circuit 6 includes a full-wave rectifier 61 that rectifies the output voltage of the detection winding 4a, and a smoothing circuit that includes a resistor _R1 and a capacitor _C2 . The voltage waveform of the smoothing capacitor C ₂ is a pulsating waveform as shown in FIG. 4, and this is led to the detection circuit 7.

The detection circuit 7 consists of a resistor R ₂ for deriving the terminal voltage of the capacitor C ₂ to the control circuit 8, and a resistor R ₃ connected between the derived end of the resistor R ₂ and the ground _. The voltage is divided by resistors R ₂ and R ₃ to form a detection voltage of an appropriate level at the output terminal of resistor R ₂ .

The control circuit 8 includes a Zener diode ZD for setting the operating level of the control circuit 8 to a predetermined level, and a switching circuit consisting of two transistors Q ₁ and Q ₂ as switching elements, and the output line 9 is connected to the collector terminal of transistor Q ₂ via field winding 2. still,
Symbol D is a flywheel diode and field winding 2
are connected in parallel. In this control circuit 8, when the detected voltage is lower than the Zener voltage (predetermined level setting voltage), the previous stage transistor
Q ₁ turns off, the next stage transistor Q ₂ turns on, and
A field current If is supplied from the field current supply source to the field winding 2 only during the period when the transistor _Q2 is turned on.

That is, as shown in FIG. 4, a level comparison is made between the pulsating waveform portion of the detection voltage Vc and the Zener voltage Vz, and a predetermined field current If is periodically applied to the field winding in an interval t where Vc<Vz. It is supplied to line 2, and the output voltage of generator G is regulated.

By the way, in the above-mentioned automatic voltage regulator, the detection voltage that is used as the reference for adjusting the field current If is the voltage divided from the terminal voltage of the smoothing capacitor _C2 . During the raising period, there is a delay in charging capacitor _C2 due to the CR time constant, so the output voltage of generator G is considered to be lower than the actual output voltage, and more field current If is supplied than necessary. The Rukoto. As a result, an overshoot phenomenon occurs in which the output voltage of the generator G increases beyond a specified value, and voltage regulation tends to become unstable. In particular, with this type of automatic voltage regulator, in order to improve voltage control accuracy, it is necessary to increase the time constant to a certain extent and reduce the slope of pulsating current. Shoots are likely to occur.

(Object of the Invention) An object of the present invention is to provide an automatic voltage regulator capable of stably regulating voltage even during a voltage ramp-up period such as when a generator starts operating.

(Structure of the Invention) In order to achieve the above object, this invention includes a rectifying and smoothing circuit that rectifies and smoothes the detection output of a winding that detects the alternating current output voltage of the generator; a detection circuit that forms a detection voltage at a predetermined voltage level based on the detection voltage; and a control circuit that controls the supply of field current to the field winding of the generator when the detection voltage is less than or equal to a set voltage. In the voltage regulator, the detection circuit includes a first resistor interposed between the rectifying and smoothing circuit and the control circuit, and a portion of the first resistor connected to the control circuit side and connected to the rectifying and smoothing circuit. a switching element provided in parallel with a smoothing capacitor in the circuit; and a switching element connected to the control circuit side portion of the first resistor via the switching element to cooperate with the first resistor to divide the detected voltage. and a second resistor forming a second resistor, and the switching element is configured such that its conductivity increases based on a rise in the output voltage of the rectifying and smoothing circuit as charging of the smoothing capacitor progresses in a starting transient state of the generator. An automatic voltage regulator is provided, comprising: an automatic voltage regulator;

(Example) Hereinafter, an example of this invention will be described with reference to the accompanying drawings. Incidentally, the same parts as in FIG. 3 are given the same reference numerals, and the explanation thereof will be omitted.

FIG. 1 shows an automatic voltage regulator according to an embodiment of this invention. The detection circuit 11 in the automatic voltage regulator 10 according to the first embodiment includes a transistor Q 3 as a switching element whose collector is connected to the output end of the resistor R ₂ (connection end to the Zener diode ZD), and a transistor Q ₃ . The resistor R ₃ connected between the emitter of Q ₃ and the ground, and the resistor R ₂
Two resistors R _{4 and} R ₅ are connected in series between the inlet end (connection end with capacitor C ₂ ) and the base of transistor Q ₃ , and the connection point between these resistors R ₄ and R ₅ is connected to ground. It consists of a capacitor _C3 .

In the above configuration, immediately after the generator G starts operating, when the terminal voltage of the capacitor _C2 is low, the transistor _Q1 is off and the transistor _Q2 is on. Therefore, the field current If is supplied to the field winding 2, and the output voltage of the generator G increases toward the specified value. As a result, the output voltage of the detection winding 4a first charges the capacitor _C2 via the resistor _R1 , and the terminal voltage thereof increases toward a predetermined value. This rising terminal voltage passes through resistor _R2 to the Zener diode.
This voltage is applied to the cathode of ZD as a detection voltage, and is also applied to the base of transistor Q ₃ via resistors R ₄ and R ₅ . At this time, since the base input of transistor Q ₃ is delayed by capacitor C ₃ , transistor Q ₃ is off during this delay time. Therefore, the terminal voltage of the capacitor _C2 is directly applied as a detection voltage to the cathode of the Zener diode ZD via the resistor _R2 .

In this state, the terminal voltage of capacitor C ₂ rises and when its DC voltage approaches the Zener voltage, the voltage level of the pulsating voltage increases and decreases the Zener voltage, turning switching elements Q ₁ and Q ₂ on and off.
Off control is started. The terminal voltage at this point is before the capacitor _C2 reaches full charge, and is a lower value than in the case explained in FIG.
In other words, the automatic voltage regulator 10 starts the voltage regulating operation from a relatively early point in time when the voltage of the generator G is rising.

On the other hand, transistor Q ₃ starts to turn on after a predetermined delay time, and its conductivity is equal to that of the capacitor.
As the terminal voltage of C ₂ increases, the terminal voltage of resistor R ₃ increases almost linearly. Then, when the terminal voltage of the capacitor _C2 exceeds the Zener voltage, it is completely turned on, and the detection circuit 11 is connected to the third
This is the same as the detection circuit 7 shown in the figure. the result,
The detection voltage used for comparison with the Zener voltage is determined by the terminal voltage of the capacitor C ₂ and the resistors R ₂ and R ₃
It is completely switched to the one related to the partial pressure ratio of , and from then on it is the same as before.

As is clear from the above explanation, the terminal voltage of resistor R ₃ increases as the degree of conductivity of transistor Q ₃ increases, and the detected voltage used for comparison with the Zener voltage is the voltage at the terminal of capacitor C ₂ . Since it continuously changes from voltage-related to voltage-divided ratio of resistors R ₂ and R ₃ and is finally completely switched, it is possible to prevent overshoot from occurring in the output voltage of the generator. can.

Next, FIG. 2 shows an automatic voltage regulator according to another embodiment. The detection circuit 21 in the automatic voltage adjustment 20 according to the second embodiment is provided with a Zener diode ZD1 in place of the resistor _R5 of the detection circuit 11 of the first embodiment, and the other components are the detection circuit 1.
It has the same configuration as 1.

In this second embodiment, transistor Q ₃
By clearly defining the ON operation timing of the automatic voltage regulator 21 by the Zener diode ZD1, the timing of starting the voltage regulation operation of the automatic voltage regulator 21 is further clearly defined.

(Effects of the Invention) As described above in detail, according to this invention, a switching element is provided in the detection circuit, and the switching element By gradually increasing the degree of conductivity, the rising terminal voltage of the smoothing capacitor becomes the detection voltage.
An early start of the voltage regulation operation is possible, thus
It is possible to prevent the occurrence of an overshoot phenomenon during the startup period of the output voltage of the generator. During the initial charging period of the smoothing capacitor, the degree of conductivity of the switching element gradually increases.
The transition to the detection voltage based on the voltage division ratio of the resistors, that is, the transition to the adjustment operation after the voltage rises can be smoothly performed.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing an automatic voltage regulator according to one embodiment of the invention, Fig. 2 is a circuit diagram showing an automatic voltage regulator according to another embodiment, and Fig. 3 is a conventional automatic voltage regulator. FIG. 4 is a characteristic diagram showing the relationship between the detection voltage Vc, the set voltage Vz, and the supply time t of the field current If as a control operation of the conventional device shown in FIG. 2... Magnetic field winding, 3... Excitation winding, 4... Output winding, 4a... Detection winding, 5... First rectifying and smoothing circuit, 6... Second rectifying and smoothing circuit, 8... ...Control circuit, 10,20...Automatic voltage regulator, 11,2
1...Detection circuit, G...Engine generator, _C2 ...
...Smoothing capacitor, _Q3 ...Transistor as a switching element, _R2 , _R3 ...Resistor.

Claims (1)

[Scope of utility model registration request] a rectifying and smoothing circuit that rectifies and smoothes the output of a winding that detects the alternating current output voltage of the generator; a detection circuit that forms a detection voltage at a predetermined voltage level based on the output voltage of the rectification and smoothing circuit; In an automatic voltage regulator comprising a control circuit that controls to supply a field current to a field winding of the generator when: a switching element connected to the control circuit side portion of the first resistor and provided in parallel with the smoothing capacitor in the rectifying and smoothing circuit; a second resistor that is connected to the control circuit side portion of the first resistor and cooperates with the first resistor to form a divided voltage of the detected voltage; An automatic voltage regulator characterized in that the degree of conductivity thereof is configured to increase based on a rise in the output voltage of the rectifying and smoothing circuit as the smoothing capacitor progresses in charging.