JPH0127440Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a voltage regulator for a magnetic alternator installed in a small vehicle, and is particularly designed to absorb instantaneous negative high voltages that occur when switching connections or charging batteries. This is to prevent destruction of the element.

FIG. 1 is an example of an energizing circuit in a general small vehicle, showing the connection state of a magnetic alternating current generator, a voltage regulator for regulating its output voltage, and a load.

1 is a magnetic alternator, and 1a and 1b are its output terminals. 2 is a voltage regulator that adjusts the output voltage from the output terminals 1a and 1b; 3 is the output terminal 1b
An AC load 5 is connected to the side, a battery 5 is a DC load 6 is connected to the output terminal 1a together with the battery 5 as a DC load via a diode 4 for half-wave rectification. 7 is a changeover switch.

The voltage regulator 2 is connected to either side of the output terminals 1a or 1b by a changeover switch 7, and when the AC load 3 is energized, it adjusts the voltage of the output terminal 1b, and also adjusts the voltage of the output terminal 1b. When no current is applied to any of the DC loads 6, it functions to control the voltage of the battery 5. In this case, the voltage of the half cycle in which charging is not performed is controlled so that an appropriate voltage is supplied to the battery 5.

Fig. 2 shows a specific example of a conventional voltage regulator 2, in which the AC output of the output terminal 1a or 1b is rectified by a full-wave rectifier circuit 2a formed by diodes _D1 to _D4 , and the output is a control voltage setting circuit formed by a capacitor C ₁ and a zener diode ZD, and when the set voltage determined here is exceeded, the amplifier transistor Tr is driven, and this operating current is passed through a diode D ₅ to the control voltage setting circuit. thyristor S is triggered. That is, the first
When the changeover switch 7 shown in the figure is connected to energize the AC load 3 side, it controls the AC output from the output terminal 1b at a constant voltage, and when it is connected to the battery 5, it controls the AC output from the output terminal 1a. , operates to perform constant voltage control during the half cycle in which battery charging is not performed, so that no abnormal voltage is applied to the battery 5.

However, in this configuration, when the changeover switch 7 is switched to the output terminal 1a side, an abnormal voltage is generated between the positive and negative terminals at that moment or when the voltage regulator performs a control operation, and the elements such as the thyristor S and the transistor Tr are can easily lead to destruction. Figure 3a shows the voltage waveform applied between the positive and negative sides of the voltage regulator 2 after the changeover switch 7 is switched to the above position, and as is clear from this figure, it is approximately three times the positive side voltage. It can be seen that a certain amount of negative voltage is generated.

Conventionally, measures to prevent this element destruction have been taken by connecting a capacitor _C2 in parallel with the thyristor S to absorb this voltage, or by increasing the withstand voltage of the transistor Tr.
Figure 3b shows the voltage waveform when capacitor _C2 is connected. However, even if this countermeasure is taken, the negative side voltage will only become slightly smaller, and the absorption effect will not be sufficient, and in the end, there is no other way than to use an element with a high withstand voltage. Ta. Therefore, the device itself has become expensive.

This idea provides a voltage regulator that eliminates the drawbacks of conventional devices, and uses a part of the rectifier circuit to absorb abnormal negative voltages that occur when switching to the battery side or while charging the battery. It is something.

A detailed explanation will be given below with reference to the illustrated embodiments. In FIG. 4, 20 is a rectifier circuit that detects and rectifies the output voltage of the output terminal 1a or 1b.
Diodes 20a, 20b and resistors 20c, 2
It is formed by a bridge circuit according to 0d. C ₁
is a control voltage setting circuit formed by a capacitor and ZD is a Zener diode.

Tr is a transistor for increasing the width, and capacitor C ₁
When a voltage exceeding the voltage set by the zener diode ZD is applied, this transistor is driven, and the thyristor S for voltage control is triggered via the diode D.

As mentioned above, the rectifier circuit 20 is formed of diodes 20a, 20b and resistors 20c, 20d, and is usually connected to the output terminal 1a or 1b.
The function is to detect the AC output voltage of the battery 5 and supply it to the control voltage setting circuit using the capacitor _C1 and the zener diode ZD. It also has a bypass effect for the negative overvoltage that occurs when the thyristor S is used to control the thyristor S, thereby playing a role in preventing destruction of the thyristor or transistor. That is, the diode 20a
, resistor 20c, diode 20b, and resistor 2
0d, so even if a negative voltage as shown in FIG. 3A occurs, it is bypassed through the diode 20a and the resistor 20c.
This voltage is not directly applied between the positive and negative sides of the voltage regulator. Therefore, thyristor S
Furthermore, failures due to destruction of these elements can be prevented without particularly increasing the withstand voltage of the transistor Tr. Also, it is not necessary to connect a capacitor in parallel to the thyristor S. In addition, the changeover switch 7
When switched to the AC load side, the AC load 3 is short-circuited, so the previous voltage will not be generated.

Figure 5 shows the voltage waveform between positive and negative that occurs when controlling a half cycle that is not on the charging side while charging the battery 5, and as is clear from this figure, the instantaneously generated negative voltage It can be seen that the rectifier circuit 20 functions as a bypass to absorb this negative voltage.

As is clear from the above explanation, this idea uses the rectifier circuit of the voltage regulator to bypass and absorb the negative high voltage that occurs instantaneously when the selector switch is switched to the battery side or while the battery is being charged. Therefore, this voltage is not applied to the thyristor or transistor constituting the voltage regulating device, and this has the effect of preventing destruction of these elements. In addition, conventional measures to prevent damage caused by high negative voltage include the use of high-voltage elements and the addition of voltage-absorbing capacitors, but these workarounds are no longer necessary, and the circuit configuration can be simplified. It can be made inexpensive.

[Brief explanation of the drawing]

Figure 1 is a current circuit diagram for a typical small vehicle, Figure 2 is a conventional voltage regulator for a magnetic alternator, and Figure 3 a and b are the positive and negative terminals of the voltage regulator shown in Figure 2. FIG. 4 is a voltage waveform diagram of the voltage regulator according to this invention, and FIG. 5 is a diagram of voltage waveforms applied to the positive and negative terminals of the voltage regulator according to this invention. 1: Magnetic AC generator, 2: Voltage regulator,
3: AC load, 5: Battery, 7: Changeover switch.

Claims (1)

[Scope of utility model registration request] In a voltage regulator for a small vehicle energizing circuit, which switches two outputs of a magnetic alternator to either an AC load or a DC load including a battery via a voltage regulator, the voltage regulator comprises: It has a bridge circuit in which two diodes are connected to the voltage control forward side of the thyristor for voltage detection, and two resistors are connected to the voltage control negative side of the thyristor. A voltage regulator for a magnetic alternator that biases the generated positive and negative surge voltages.