JPH0823700A - Generated power supply device - Google Patents

Abstract

PURPOSE:To prevent a DC output voltage from increasing excessively in a generated power supply device for obtaining the DC output voltage by rectifying the generated voltage of a generator. CONSTITUTION:A generated voltage is rectified by a rectifier 2 for charging a capacitor 5 connected between DC output terminals 11 and 12. The charged voltage is taken out as a DC output voltage. Power is fed to an AC load 10 via an inverter 7. This sort of generated power supply device is provided with a voltage detector 13 and a switching device 14 to suppress overvoltage. The voltage between the DC output terminals is monitored by the voltage detector 13 and it is detected that a voltage exceeds a reference value preset to the voltage detector 13 and the regenerated voltage from an armature coil winding 10 is short-circuited by the switching device 14 when the voltage becomes excessive. The capacitor 5 is not charged during the short-circuiting but discharges voltage, thus suppressing an overvoltage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a generator power supply device which prevents an output voltage from becoming excessive.

[0002]

2. Description of the Related Art A vehicle or the like is equipped with a generator power supply device that rectifies the voltage of a generator driven by an engine to produce an output voltage. In this type of power generator, the field current is controlled to keep the generated voltage at a predetermined value, the generated voltage is rectified to feed the DC load, and the AC load is converted into AC by an inverter. Power is being supplied.

FIG. 2 is a diagram showing such a conventional power generation power supply device. In FIG. 2, 1 is a generator, 101 is an armature winding, 102 is a field winding, 2 is a rectifier, 3 is a voltage regulator, 31 is a diode, 32 is a transistor, 33 is a voltage detector, and 4 is an output. Line, 5 is a capacitor, 7 is an inverter, 8 is an inverter drive circuit, 9 is a switch, 10
Is a load, and 11 and 12 are output terminals. A synchronous generator is used as the generator 1.

The voltage generated by the generator 1 is rectified by the rectifier 2 and charges the capacitor 5. Both ends of the capacitor 5 are connected to the output terminals 11 and 12, and the charging voltage is taken out as an output voltage. The voltage regulator 3 controls the field current so that its output voltage becomes a predetermined value. The field current is
It is controlled by turning on and off the transistor 32. The voltage detector 33 outputs the rectified output voltage of the rectifier 2 to the voltage detector 3
3 is compared with a reference value set in advance, and if it is larger than the reference value, the transistor 32 is turned off, and if it is smaller, it is turned on. The diode 31 is a flywheel diode and provides a path through which a current for discharging the energy of the field winding 102 (for preventing surge voltage) flows when the field current is turned off.

In this example, since the load 10 is an AC load, power is supplied from the output terminals 11 and 12 via the inverter 7 and the switch 9. As the inverter 7,
For example, there is one using a transistor as a switching element. The inverter drive circuit 8 is a circuit that supplies a switching signal for AC conversion to the switching element of the inverter 7.

FIG. 3 is a diagram showing a generator output characteristic at a constant rotation speed. The parameter is the value of the field current. FIG. 3A shows a case where the speed is constant and FIG. 3B shows a case where the speed is constant. The curves a, b, c, d, and h are the generator output current (output current of the rectifier 2) and the generator output when the field currents are If ₁ , If ₂ , If ₃ , If ₄ , If ₅ , respectively. The relationship with the voltage (output voltage of the rectifier 2) is shown.

Even if the engine speed changes, it is necessary to supply a constant voltage to the load. If the constant voltage is V ₁ , for example, it is necessary to output V ₁ in both low speed rotation and high speed rotation. If the rotation speed does not change and the current required from the load (generator output current) also does not change, the output voltage is kept at a constant value V ₁ by keeping the field current at a certain constant value. However, if the current required from the load changes and the field current remains the same, the operating point moves on the curve of the field current, so the output voltage also changes. In such a case, as shown by the dotted line in FIG. 3 (a), it is necessary to maintain the output voltage at V ₁ by changing the field current and moving to different curves one after another. The voltage regulator 3 controls the field current.

As can be seen by comparing the heights of the intersections of the vertical axes and the curves in FIGS. 3A and 3B, the magnitude of the no-load voltage is very large at high speeds. Therefore, when the load is cut off at high speed (no load), the output terminals 11, 1
An excessive voltage is generated between the two. Hereinafter, the excessive voltage generated when the load is cut off will be described in detail.

FIG. 4 is a diagram showing a change over time in the generator output voltage and the like when the load is cut off in the conventional power generator. 4A shows a change in the generator output voltage, FIG. 4B shows a change in the field current, and FIG. 4C shows a change in the generator output current. The horizontal axis is time (t) in all cases. In FIG. 2, it is assumed that the voltage V ₁ and the current I ₁ are supplied to the load 10 and the switch 9 is cut off at time t ₁ . The operating point on each graph of FIG. 4 at the time of interruption t ₁ is A, and the operating points at subsequent times t ₂ , t ₃ and t ₄ are B, C and D, respectively.
And

Even if the switch 9 is cut off, the armature winding 10
Because 1 has an inductance, the current flowing through the armature winding 101 (that is, the generator output current) cannot immediately reach 0. The current continues to flow in the path for charging the capacitor 5, and gradually decreases to I _{2 at} point B and I _{3 at} point C as shown in FIG. 4C.

As can be seen from FIG. 3 (b), when the load is cut off at the operating point A and the generator output current starts to decrease from I ₁ , the operating point is on the curved line unless the field current is changed. As it moves, the generator output voltage rises. When the voltage detector 33 detects the rise in the output voltage as described above, it turns off the transistor 32 in an attempt to cut off the field current. However, due to the inductance of the field winding 102, the field current is not immediately zero. It cannot be. Field current is diode 3
It continues to flow on the route through 1, and gradually decreases. Figure 4 (b)
Shows the situation. At point A when the load is cut off, I
_The field current, which was _f10 , decreases to I _{f9 at} point B, I _{f8 at} point C, and I _{f7 at} point D.

When the generator output current decreases to I ₁ , I ₂ and I ₃ and the field current decreases to I _f10 , I _f9 , I _f8 and I _f7 , the operating point in FIG. B → C → D, and so on, going over the curve N → R → C → D, and the generator output voltage rises. Then, finally, it rises to a point where it becomes a no-load voltage of a certain field current, and stops increasing (in FIG. 3B, no-load voltage V _{5 of} field current If ₇ (curve G)). Has risen until it has stopped climbing). This voltage is much higher than the rated voltage V ₁ supplied from the output terminals 11 and 12. FIG. 4 (a) depicts such a temporal change in the generator output voltage.

Some circuit (for example, the inverter 7 in FIG. 2) may be connected between the output terminals 11 and 12 and the switch 9. In such a case, an overvoltage may be applied to the circuit. become. Therefore, it is necessary to use an element that withstands a voltage much higher than the rated voltage V ₁ as an element forming the circuit, which is expensive. Therefore,
In order to prevent the voltage appearing at the output terminals 11 and 12 from becoming high, it has been considered to use a large-capacity capacitor as the capacitor 5 or connect a large-capacity battery instead of the capacitor 5.

As a document relating to a power generation power supply device using a generator driven by an engine, for example, Japanese Patent Laid-Open No.
-106929 is available.

[0015]

In the above-mentioned conventional power generation device, a large-capacity capacitor or a large-capacity battery is used as a means for absorbing an overvoltage generated when the load is cut off. However, there was a problem that the cost would be high. Further, when a battery is used, there is a problem that the weight of the entire device becomes large. An object of the present invention is to solve the above problems.

[0016]

In order to solve the above problems, according to the present invention, a generator, a rectifier for rectifying a generated voltage of the generator, a capacitor connected to both ends of the rectifier, and a rectifier In a generator power supply device that detects a rectified output voltage and controls the generated voltage to a predetermined value, and the voltage of the capacitor is a DC output voltage, the voltage of the capacitor is higher than a normal DC output voltage. A voltage detector that detects that the voltage exceeds a set reference value, and a detection signal from the voltage detector that the voltage exceeds the reference value is shorted to the DC output terminal of the armature winding of the generator. However, it is provided with an opening / closing device that releases the short circuit when there is no detection signal.

In order to quickly reduce the overvoltage, a resistor for a discharge path is connected in parallel with the capacitor, or a resistor for a discharge path and the switchgear are connected in series, which is connected in parallel with the capacitor. May be. A transistor or a thyristor can be used as the switching element of the switching device.

The switching device short-circuits the armature windings of the generator with bidirectional switching elements in response to a detection signal from the voltage detector that the reference value has been reached. It is also possible to adopt a configuration in which the short circuit is released.

As a voltage detector, the voltage of the capacitor has a lower reference value which is set higher than a normal DC output voltage, and an upper reference value which is set higher than the lower reference value. Using something that detects that
As a switchgear, the armature winding of the generator is short-circuited to the DC output terminal by the detection signal from the voltage detector that the upper reference value is reached, and then the short circuit is made by the detection signal that the lower reference value is reached. You may use the thing released.

[0020]

[Operation] The voltage of the capacitor connected between the DC output terminals is monitored by a voltage detector, and when an overvoltage is about to occur, the armature winding is used for the period until the voltage drops from the upper reference value to the lower reference value. The generated voltage from the line is short-circuited by the switchgear. During that time, the capacitor connected to the output side of the rectifier that rectifies the generated voltage is not charged but rather discharged, so that the overvoltage is suppressed. To suppress this overvoltage, a voltage detector and a switchgear are required.
These costs are lower than the cost of using a large-capacity capacitor so that the overvoltage can be suppressed or connecting a large-capacity battery instead of the capacitor.

[0021]

【Example】

(First Embodiment) Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing a first embodiment of the present invention. Reference numerals correspond to those of FIG. 2, 6 is a resistor, 1
3 is a voltage detector, 14 is a switchgear, 141 is a diode, and 142 is a transistor. The resistor 6 is for discharging the capacitor 5. The switchgear 14 includes the armature winding 10
1 and a transistor 141 that rectifies the generated voltage from No. 1 and a short circuit between the cathode of the diode 141 and one of the DC output terminals (for example, the negative side terminal of the DC output terminal). The transistor 142, which is the switching element of the switching device 14, is connected to the voltage detector 13
It is turned on or off by a signal from.

The voltage detector 13 is for detecting a DC output voltage, and its detecting operation has a hysteresis characteristic. That is, as a reference value for voltage comparison,
An upper reference value V _H and a lower reference value V _L are provided, and a signal for turning on the transistor 142 is output when it is detected that the DC output voltage reaches V _H , and even if it is lower than that, it is immediately turned off. A signal is not output, but is output when it is detected that the voltage has dropped to V _L. The lower reference value V _L is set to be a value slightly higher than the normal DC output voltage (rated voltage V ₁ ).

In the present invention, the overvoltage suppressing operation is performed not only when the load is cut off, but also whenever an overvoltage occurs. The outline of the operation is as follows. That is, when the DC output voltage (voltage between the output terminals 11 and 12) reaches the upper reference value V _H , the transistor 142 is turned on, so that the rectifier 2 does not output a rectified output. Therefore, the DC output voltage decreases as the capacitor 5 discharges. Lower reference value V _L
Then, the transistor 142 is turned off, so that the rectifier 2 outputs the rectified output again. In this way, even if there is a factor that causes overvoltage, the value is maintained between V _H and V _L , so overvoltage does not occur. When it becomes lower than the lower reference value V _L , the voltage regulator 3 maintains the rated voltage V ₁ .

Next, the detailed operation of suppressing the overvoltage will be described by taking as an example the case where the overvoltage is about to occur due to the load interruption. FIG. 5 is a diagram showing temporal changes in the generator output voltage and the like when the load is cut off in the present invention. 5 (a) is a generator output voltage (voltage between output terminals 11 and 12), FIG.
5B shows the output signal of the voltage detector 13, FIG. 5C shows the field current, and FIG. 5D shows the collector current of the transistor 142. P _{1 to} P ₈ are operating points on the graph.

It is assumed that the switch 9 is turned off at point P ₁ to cut off the load. Then, as described in the conventional example, the generator output voltage rises and the field current decreases. When the generator output voltage reaches the upper reference value V _H (the operating point P in FIG. 5A)
₂ ), the voltage detector 13 outputs an ON signal and turns on the transistor 142. The transistor 142 is shown in FIG.
A collector current flows as shown in FIG. 2 and shorts the armature winding 101 to the DC output terminal (in this case, the negative terminal of the DC output terminals). After that, the output terminals 11, 1
The voltage between the two (generator output voltage) decreases as the capacitor 5 discharges. The resistor 6 is for promoting discharge of the capacitor 5, and is not essential. If the resistor 6 is connected, the upper reference value V _H can be quickly reduced.

When the voltage of the capacitor 5 drops to the lower reference value V _L (operating point P _{3 in} FIG. 5A), the voltage detector 1
3 is turned off and the transistor 142 is turned off. At this point, when the field current is still flowing and the generator output voltage tends to increase, it again increases to the upper reference value V _H. After that, it goes up and down between the upper reference value V _H and the lower reference value V _L. The field current gradually decreases as shown in FIG. 5 (c), but when the generator output voltage reaches the set voltage of the voltage regulator 3 (= rated voltage V ₁ ), no load ( (Because the load is cut off) it becomes a field current that maintains that voltage and stabilizes.

Instead of the switchgear 14, output terminals 11, 1
It is theoretically possible to suppress the overvoltage by connecting a transistor between the two and turning it on when an overvoltage is about to occur. However, in such a case, the transistor has a form in which both ends of the capacitor 5 are short-circuited, so that a large discharge current flows and is destroyed.

(Second Embodiment) FIG. 6 is a diagram showing a second embodiment of the present invention. The difference from the first embodiment of FIG. 1 is the connection position of the resistor 6. In the first embodiment, the capacitor 5 is connected in parallel, but in the second embodiment, the transistor 142 of the switchgear 14 connected in series is connected in parallel with the capacitor 5. In this case, the current flows through the resistor 6 because the transistor 142
Is turned on (in the first embodiment, the current flows through the resistor 6 not only when the transistor 142 is turned on, but also when the generator 1 stops the power generation). The overvoltage suppressing operation is similar to that of the first embodiment.

(Third Embodiment) FIG. 7 is a diagram showing a third embodiment of the present invention. The difference from the first embodiment of FIG. 1 is the configuration of the opening / closing device 14. In this embodiment, a thyristor (silicon controlled rectifying element) is used as the switching element. The thyristor turns on when the voltage detector 13 outputs an on signal.

(Fourth Embodiment) FIG. 8 is a diagram showing a fourth embodiment of the present invention. The difference from the first embodiment of FIG. 1 is the configuration of the switchgear 14 and the way of connecting it. In this embodiment, a triac is used as an opening / closing element, and each winding of the armature winding 101 is short-circuited so that no output is output from the rectifier 2. The triac is also called a bidirectional thyristor, and turns on when the voltage detector 13 outputs an on signal.

(Other Embodiments) The voltage detector 1 has been described above.
3 has an upper reference value V _H and a lower reference value V _L , and has an intentional hysteresis characteristic, and is explained without considering the delay of the operation time in the voltage detector 13 and the switchgear 14. did. However, in reality, the voltage detector 13 and the switchgear 1
4 has an operation delay, and as will be described later, it has a hysteresis characteristic substantially due to the operation delay.
Therefore, if the hysteresis characteristic in a time width longer than the operation delay is not required, each embodiment described above does not have two reference values of the upper reference value V _H and the lower reference value V _L , but 1 Even if the voltage detector 13 having one reference value is used, the same effect can be obtained.

That is, as the voltage detector 13, one having a reference value set higher than the normal DC output voltage is used, and the armature winding 101 of the generator 1 is driven by the detection signal that the reference value is exceeded. Short to the DC output terminal. Then, the short circuit is released by the detection signal that the voltage is lower than the reference value. This will be explained below.

FIG. 9 is a diagram showing a temporal change in the generator output voltage and the like when the load is cut off in the present invention when the voltage detector 13 is not provided with the hysteresis characteristic. The reference numerals correspond to those in FIG. V _{K in} FIG. 9A is a reference value provided to the voltage detector 13, and its value is set to a value higher than the normal DC output voltage (rated voltage V ₁ ).

It is assumed that the switch 9 is turned off at the point P ₁ to cut off the load. The voltage rises and the reference value V is reached at the operating point P _{9.
Reach K} The voltage detector 13 outputs a detection signal and tries to turn on the switchgear 14, but due to the operation delay of the voltage detector 13, from the time when the voltage reaches the reference value V _K (P ₉ ) until the detection output is output. Takes some time. That time is T _{1 shown} in FIG. 9B. After the detection output is transmitted to the switchgear 14, it takes some time before the switchgear 14 is turned on (P ₁₀ ) due to the operation delay of the switchgear 14. That time is shown in Figure 9.
It is T ₂ described in (b).

Therefore, since the voltage reaches the reference value V _K (P ₉ ) and the switchgear 14 is turned on (P ₁₀ ), there is a delay of the total time T ₁ of T ₁ and T _2. The output voltage of the generator is slightly higher than the reference value V _K at the time of actual turning on (see FIG. 9A). The same applies when the voltage drops. Even if the reference value V _{K is} lowered at the operating point P ₁₁ , the switchgear 14 is accordingly turned off (P ₁₂ ).
After all, there is a delay of time T. In the meantime, it continues to fall, and when it is actually turned off, the value is a little lower than the reference value V _K. This delay time T created by the operation delay of the voltage detector 13 and the switchgear 14 itself.
However, it is a source of substantially exhibiting hysteresis characteristics. Therefore, as the voltage detector 13 to be used, depending on the required hysteresis characteristic, the upper reference value V is forced.
It is not necessary to use the one in which _H and the lower reference value _VL are set, but the one in which one reference value is set may be used.

[0036]

As described above, according to the generator power supply device of the present invention, the voltage of the capacitor connected between the DC output terminals is monitored by the voltage detector, and when an overvoltage is about to occur, the voltage is higher. The generated voltage from the armature winding is short-circuited by the switchgear during the period from the reference value to the lower reference value. During that time, the capacitor connected to the output side of the rectifier that rectifies the generated voltage is not charged but rather discharged, so that the overvoltage is suppressed. A voltage detector and a switchgear are required to suppress this overvoltage.The cost of these capacitors is large enough to suppress the overvoltage, or a large-capacity battery is connected instead of the capacitor. It is cheaper than the cost to do.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram showing a conventional power generation power supply device.

FIG. 3 is a diagram showing a generator output characteristic at a constant rotation speed.

FIG. 4 is a diagram showing a temporal change of a generator output voltage and the like when a load is cut off in a conventional example.

FIG. 5 is a diagram showing temporal changes in the generator output voltage and the like when the load is cut off in the present invention.

FIG. 6 is a diagram showing a second embodiment of the present invention.

FIG. 7 is a diagram showing a third embodiment of the present invention.

FIG. 8 is a diagram showing a fourth embodiment of the present invention.

FIG. 9 is a diagram showing a temporal change of a generator output voltage and the like at the time of load shedding in the present invention when the voltage detector does not have a hysteresis characteristic.

[Explanation of symbols]

1 ... Generator, 101 ... Armature winding, 102 ... Field winding,
2 ... Rectifier, 3 ... Voltage regulator, 31 ... Diode, 32
... Transistor, 33 ... Voltage detector, 4 ... Output line, 5
... condenser, 6 ... resistance, 7 ... inverter, 8 ... inverter drive circuit, 9 ... switch, 10 ... load, 11, 12
... output terminal, 13 ... voltage detector, 14 ... switchgear, 14
1 ... Diode, 142 ... Transistor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Satoshi Tozawa 8 Tsutana, Fujisawa City, Isuzu Central Research Institute (72) Inventor Kazumi Nishizawa 1-12-11 Higashirokugo, Ota-ku, Tokyo Nikko Denki Kogyo Incorporated (72) Inventor Kazuhiro Takayama 1-12-11 Higashirokugo, Ota-ku, Tokyo Within Nikko Electric Industry Co., Ltd.

Claims (8)

[Claims] 1. A generator, a rectifier for rectifying a generated voltage of the generator, a capacitor connected to both ends of the rectifier, and a rectified output voltage of the rectifier to detect the rectified output voltage and control the generated voltage to a predetermined value. And a voltage regulator for detecting the fact that the voltage of the capacitor is higher than a normal DC output voltage and is equal to or higher than a reference value in a generator power supply device using the voltage of the capacitor as a DC output voltage. A detector and a switchgear that short-circuits the armature winding of the generator to a DC output terminal in response to a detection signal from the voltage detector when the reference value is exceeded, and releases the short-circuit when there is no detection signal. A power supply device characterized by comprising. 2. The generator power supply device according to claim 1, wherein a resistor for a discharge path is connected in parallel with the capacitor. 3. The generator power supply device according to claim 1, wherein a resistor for a discharge path and a switchgear are connected in series, and the resistor is connected in parallel with the capacitor. 4. A transistor is used as an opening / closing element of the opening / closing device.
The power generation power supply described. 5. The generator power supply device according to claim 1, wherein a thyristor is used as the switching element of the switching device. 6. A generator, a rectifier for rectifying a generated voltage of the generator, a capacitor connected to both ends of the rectifier, and a rectified output voltage of the rectifier to detect the rectified output voltage and control the generated voltage to a predetermined value. And a voltage regulator for detecting the fact that the voltage of the capacitor is higher than a normal DC output voltage and is equal to or higher than a reference value in a generator power supply device using the voltage of the capacitor as a DC output voltage. The armature winding of the generator is short-circuited by a bidirectional switching element in response to a detection signal from the detector and the voltage detector when the voltage exceeds the reference value, and the short-circuit is released when there is no detection signal. A power supply unit comprising a switchgear. 7. As a voltage detector, the voltage of the capacitor has a lower reference value set higher than a normal DC output voltage, and has an upper reference value set higher than the lower reference value. As a switchgear, a voltage detector that detects that the upper armature winding of the generator is short-circuited to the DC output terminal according to the detection signal from the voltage detector that the upper reference value has been reached, and then the lower reference value. 2. The power supply unit according to claim 1, further comprising an opening / closing device for releasing the short circuit in response to a detection signal indicating that 8. As a voltage detector, the voltage of the capacitor has a lower reference value set higher than a normal DC output voltage, and has an upper reference value set higher than the lower reference value. A voltage detector for detecting that, as a switchgear, short-circuiting the armature windings of the generator with bidirectional switchgear elements by a detection signal from the voltage detector that has become a higher reference value, 7. The generator power supply device according to claim 6, further comprising an opening / closing device that cancels the short circuit in response to a detection signal that a lower reference value has been reached.