JPH0126251B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to brushless alternators, and more particularly to brushless alternators equipped with shorted diode protection devices.

[Background technology]

Many years ago, when manufacturing brushless alternators where the field excitation was supplied from an AC exciter and rotating rectifier assembly, detection of shorted diodes in the rotating rectifier assembly was used.
Always faced with unique problems. When shorting diodes are present in the rotary rectifier assembly, short circuits across the exciter windings are formed intermittently. Also, when this exciter field excitation is maintained, a lot of short circuit current will flow in the exciter armature winding. This large amount of short circuit current can result in extensive damage or destruction of the exciter and can also result in damage to the main generator and other components of the system.

Among the effective solutions to this shorted diode problem is that proposed by Calfee et al. in Patent No. 3,210,603. What is shown in this patent by Calfee et al. is a rotating field generator in which the exciter field current is monitored and the field circuit is interrupted if the rotating diode is damaged. It is a machine. A signal representing current is coupled by a current transformer to a diode bridge rectifier and an RC filter. When the diode is damaged, the amplitude of the AC ripple in the field circuit increases and its frequency decreases. The amplitude of the rectified voltage from the diode bridge rectifier and RC filter increases, energizing the relay and opening the field circuit. What has been described above is also effective for separating the DC component of the field current from the AC component. The design of the current transformer is recognized to be critical since the alternator is DC biased. Its DC bias is equal to the average exciter field ampere. This DC bias requires heavy and expensive current transformers. In this invention, which will be explained later,
There is no need for such a current transformer, and there are no problems with the separation involved in detecting the current components.

An alternative solution to the shorted diode problem is provided by Hyvarinen et al.
Disclosed in No. 3534228. Disclosed therein is a sensing circuit consisting of a series resistor in the exciter field circuit and a transformer connected across the series resistor through a DC blocking capacitor.
The voltage output of this transformer is passed through an RC filter.
Coupled to a diode bridge rectifier and field current regulator. In the Hyverinen et al. patent, an AC conducting coupling circuit to the exciter field is required to generate an AC error voltage proportional to the oscillations or ripples in the field current.
A device for limiting the exciter field current makes it possible to protect the short-circuit diode when this AC error voltage exceeds a certain predetermined criterion. The present invention, which will be described later, provides a short-circuit diode protection device that does not require the inclusion of many current components in the field circuit line, thereby improving the reliability of short-circuit diode detection. As a factor, the possibility of overall damage to the components is reduced.

[Disclosure of the invention]

This invention relates to a shorted diode protection system for brushless alternators of the type having energized exciter field windings.
This system includes: sensing the voltage differential across the exciter field;
This voltage difference is paired with the generator load current, thereby providing an output signal with a predictable value over a range of normal generator load currents. This output signal has a property that it takes a higher value when a short circuit occurs in the diode. A different circuit arrangement responsive to the output signal is configured to cause a break in the exciter field whenever the output signal exceeds a preset value within a range of normal load currents. output is generated.

Accordingly, it is a primary object of the present invention to provide a brushless alternator with short circuit diode protection that does not require the detection and use of field current or field current ripples to provide protection. It's about doing.

Another object of the invention is to detect a voltage difference across an exciter field winding, and when the voltage difference across the exciter field winding exceeds a preset value,
An object of the present invention is to provide a short-circuit diode protection system for a brushless alternator, which is capable of cutting off the energization of the exciter field at any time.

A further object of the invention is the use of a microprocessor in a shorted diode protection system. This microprocessor stores a current value within a preset range within the normal generator load current range.
when the voltage difference detected across the exciter field winding exceeds the stored value within a preset range;
A relay is energized to de-energize the exciter field.

In achieving the foregoing objects, the generator of the present invention includes a combination of a fixed armature member and a rotatable member having a field winding. The exciter with the fixed member is equipped with an exciter field winding. The rotatable member also has a rectifier assembly and an armature member rotatable therewith. The rectifier assembly is
The exciter armature member and the generator field winding are electrically connected to each other, and the generator field winding is excited with direct current. The exciter field winding is provided with a circuit for supplying direct current.

Also included in the generator system is a circuit arrangement that senses the voltage difference across the exciter field windings and pairs this voltage difference with the generator load current, thereby causing normal operation. In a range of generator load currents, an output signal having a value within a predictable range is output. This output signal has the property of assuming a value in a higher range when a short circuit occurs in the diode. The different circuit arrangement is responsive to the output signal to cause the exciter field to ebb and flow whenever the output signal exceeds a preset value within the normal load current range. Output is generated that causes

A circuit arrangement for sensing the voltage difference is electrically coupled across the exciter field winding and includes a multiplexer electrically coupled to the exciter field winding. It is. A microprocessor, which is part of a separate circuit arrangement, is also electrically coupled to the multiplexer. The multiplexer is adapted to accept control signals from the microprocessor as well as signals from the exciter field windings.

A load current sensing circuit is coupled to the output of the generator, and the output is coupled to the multiplexer.

Also included in the circuit arrangement for sensing voltage differences is a digital-to-analog converter electrically coupled to the output from the multiplexer. This converter provides the aforementioned output signal to the microprocessor, which may either have a predictable range of values or a higher range of values, such as would occur with a shorted diode. It has either one of the following.

Also included in the separate circuit arrangement responsive to the output signal is a generator-controlled relay driver electrically coupled to the relay. and,
By energizing this relay, control is performed to cut off the energization of the exciter field.

The microprocessor stores values in a preset range within the normal load current range. The relay is then energized to cut off the exciter field whenever its output signal exceeds a preset value for any given load current in the normal range. Finally, with energization of this relay, a resistive element is controllably electrically connected across the excitation field winding. Thus, when a diode short circuit is detected, the exciter field winding is de-energized and any self-excitation of the generator is attenuated.

Other objects and advantages of the invention will become apparent from the following description taken in conjunction with the accompanying drawings.

[Explanation of Examples]

First, referring to FIG. 1, a brushless alternator device according to an embodiment of the present invention is schematically shown. The generator here is a normal one, and is provided with a rotatable assembly 10 including a rotatable shaft (not shown), on which is a field winding 11 that rotates together with a three-phase electric machine. A child winding 12 and a rectifier assembly 13 are attached. Rectifier assembly 13 is electrically connected to field winding 11 as shown and also includes diodes 14,1
5, 16, 17, 18 and 19 are included. A three-phase stator winding 20 is provided, which forms part of a stator structure (not shown). Generator output conductors 21, 22 and 2
3 is shown exiting the dotted outline of the three-phase stator winding 20 and entering the current transformer arrangement depicted by the dotted block 26. The function of this current transformer array 26 will be described in more detail below. A typical type of permanent magnet generator 30 includes a transistor Q, a capacitor C, a resistor R ₁ , and a
It is used in conjunction with a full-wave rectifier bridge 31, along with conventional voltage regulator components such as diodes CR1, CR2. The voltage regulator components then follow the electrical leads 32 and 3 on either side of the exciter field winding 36.
3 are electrically interconnected as shown. The exciter field winding 36 is mounted on a stator (not shown) and is connected to a full-wave rectifier bridge 31.
DC excitation from a permanent magnet generator 30 is provided via the electrical connections and components previously described. A permanent magnet field member, not shown, is driven from a main generator shaft, also not shown, through which the exciter voltage is applied to the exciter field whenever the main generator shaft is rotated. It will be given to the magnetic winding 36. Normally closed disconnect contacts 37, 38 and 39 are shown in leads 41, 42 and 43, which connect the permanent magnet generator 3.
0 is interconnected with a full-wave rectifier bridge 31. The opening of these normally closed breaker contacts 37, 38 and 39 will be described in more detail below.
Here, by opening these breaker contacts 37, 38 and 39, the exciter field winding 3
Note that the DC power to 6 is then cut off.

A pair of voltage divider networks, indicated generally by the reference numerals 46 and 47 and their associated bifurcated arrows, are connected to lead 33 at point 48 and to lead 33 at point 49, respectively. It is electrically connected to the lead 32. These voltage divider networks 46 and 47 are connected on leads 50 and 51 to multiplexer 52 to selected values for voltage divider resistors R ₂ , R ₃ , R ₄ , R ₅ and voltage divider capacitors C1, C2. gives a reduced voltage signal accordingly.

A sensing device, which is a circuit arrangement 55 shown in dashed outline, senses the voltage difference across the exciter field winding 36 and uses this voltage difference to generate electricity in a manner to be described below. Pair with machine load current. As noted earlier, multiplexer 5
2 continuously accepts voltage signals on leads 50 and 51. These voltage signals are then directly proportional to the voltage sensed in leads 32, 33 on either side of exciter field winding 36.

The current transformer array 26 schematically shown has leads 27, 2 to a three-phase load current averaging circuit 56.
8 and 29, it continuously outputs a signal representative of the load current that the generator is required to output. Load current averaging circuit 56 has a single signal output on lead 57 that is output to multiplexer 52 . Multiplexer 52
is controlled by signals from microprocessor device 60 via lead 61. The multiplexer 52 is an analog-to-digital converter 59
It has a single signal output provided on lead 58 for the signal. Analog-digital converter 5
9 converts the signal on lead 58 to a signal in digital form on lead 62 for use by microprocessor device 60.

Microprocessor device 60 is programmed in the following manner. That is, multiplexer 52, under control of signals on lead 61 from microprocessor device 60,
Reduced voltage signal on 0,51 and lead 5
It is programmed in such a way that it continuously accepts the average load current signal on 7 and passes it to its output 58. The sequence in which the voltage and load current are sampled is a design matter dependent on the programming of the microprocessor device. For reasons that will become apparent later, what is required in a microprocessor is that the differential voltage sensed at a given average load current be stored within the microprocessor for the given average load current. There should be a pair of conditions that the microprocessor logic is allowed to set to determine whether a preset value has been exceeded. A signal is generated on lead 68 to generator control relay driver and relay 63 whenever a differential voltage is detected to exceed a preset and stored value at a given load current. Ru. Then, this driver/relay 63 is energized, and the normally closed disconnector contact 37,
38 and 39 are opened, thereby deenergizing the exciter winding 36.

What is to be noted here is that the normally open breaker contact 66 is closed by the mechanical connection 64 from the generator control relay driver/relay 63 via the mechanical connection 64a. control to ensure that When this breaker contact 66 is closed, a resistor 67 is placed across the leads 32, 33 to the exciter field winding 36, thereby providing shorted diode detection. Any self-excitation of the generator is attenuated whenever the exciter field winding is deenergized.

A microprocessor unit 60 and a generator control relay driver and relay 63 are shown included within a dashed block 65 to represent the means responsive to the output signal on lead 62. , an output is generated on connection 64 which de-energizes exciter field winding 36 whenever the output signal on lead 62 exceeds a predetermined value within the range of normal load currents. be made to do.

Before explaining the detailed operation of the device in FIG. 1 in conjunction with the signal waveform diagrams in FIGS. Please refer to FIG. 3 shown in FIG. This third figure is
1 is a plot of the voltage difference across a generator excitation winding, such as winding 36 in FIG. 1, over a range of normal load currents, with and without a shorting diode; It is something.

In FIG. 1, both ends of exciter field winding 36 are connected to leads 32 and 33. Reference letter "A" and combinations thereof. The arrow points to point 48 on lead 33, and the reference letter "B" and associated arrow point to lead 33.
It points to point 49 on 2.

Diode 14 in rotating rectifier assembly 13
.about.19 is in good operating condition, the voltage PtA at point "A" is represented as voltage curve 70 reduced by voltage divider network 46, as shown in FIG. . Similarly,
When the diodes 14-19 are in good working condition, the voltage PtB at point "B" is equal to the voltage curve 71.
It is expressed as At any given load current, the distance between voltage curves 70, 71 represents the voltage difference across exciter field winding 36.

When one of the diodes 14-19 is shorted, the rotary generator field 11 acts as a source of electrical energy for the exciter field winding 36.
This source of electrical energy is connected to point “A” with respect to ground.
and “B” voltage. A shorted diode is present and the generator field 1
1 acts as a voltage source, the negative side in exciter field winding 36 is limited only by the value of CR2 below ground. Exciter field winding 36
The positive side of supplies energy to capacitor C via lead 32, thereby
The voltage at "B" is ensured. This voltage secured at point "B" back biases the permanent magnet full-wave rectifier bridge 31.
bias). The voltage at point "B" is reflected in capacitor C, and field current is caused to flow from point "B" through capacitor C and diode CR2, thereby affecting the voltage at point "A". be done.

Returning now to FIG. 3, it can be seen that a shorted diode voltage curve 72 at point "A" and a shorted diode voltage curve 73 at point "B" are plotted. It is also observed that the voltage difference between the good diode voltage curves 70 and 71 is always smaller than the voltage difference between the shorted diode voltage curves 72 and 73 at all load currents.

FIG. 4 is a plot of the exciter field winding voltage difference curve, plotted within the range of normal generator load currents. “Good diode”
Solid line differential voltage curves 74 and 7 when
5 is shown to be within a predictable range of values when the generator is operated at the same frequency but at different temperatures. “Short diode”
The dotted line differential voltage curves 76 and 77 are shown to have values in a higher range when .

The protection setting curve 78 is based on the microprocessor 60.
represents a preset value stored in the Whenever the absolute value of the differential voltage across the exciter field winding 36 is greater than this protection setting curve 78, the generator control relay driver and relay 63 is engaged, as shown in FIG. Forced,
Normally closed or disconnected contact 3 via mechanical connection 64
By opening 7, 38 and 39, the exciter field winding 36 is deenergized.

Reference is now made to Figures 2a to 2d as waveform diagrams for a generator operating with no load at 400Hz. These Figures 2a-2d will be discussed in connection with the generator arrangement of Figure 1 above.

FIG. 2a is a time series plot of the voltage at point "A" showing ideally full-wave rectified square wave forms 80, 81, output by the full-wave rectifying bridge 31. 82 and 83 are shown. In time, it can be seen that a diode short occurs at the end of the square wave 83 and the average voltage drops from 131.6 volts DC to 115 volts DC while the peak voltage occurs.

Figure 2b plots the voltage at point "B" over the same time interval as Figure 2a. Here, during the period in which the shorting diode is present, the voltage increases, as indicated by reference numeral 85.

In FIG. 2c, the output voltages of the resistive voltage divider at points "A" and "B" are plotted apart from each other. Here, the sudden increase in Δ(V _B −V _A ) at time point 86 is assumed to be greater than the preset value of protection setting curve 78 in FIG. recognized by. From this microprocessor 60, an output having the waveform shown in FIG. 2d is obtained.

What is easily recognized from the above-mentioned matters is that
The invention described herein provides a shorted diode protection method that does not require detecting and using the field current or ripples in the field current to provide shorted diode protection. A brushless alternator with protection features is provided. All of this is advantageously accomplished by sensing voltage differences across the exciter field windings. That is, the exciter field is de-energized whenever the voltage difference across the exciter field winding exceeds a preset value stored within the microprocessor device. It is.

Although this invention has been described in conjunction with the specific embodiments illustrated, it is understood that various changes may be made without departing from the spirit of the invention as set forth in the claims. Various modifications may be made, including, but not limited to, the use of suitable analog circuitry in place of the multiplexer, converter, and multiplexer combination used in the above embodiments. , is obvious to those skilled in the art.

[Brief explanation of drawings]

FIG. 1 is a circuit configuration diagram schematically showing a generator device which is an embodiment of the present invention, and FIGS. 2a to 2d.
The diagram shows the generator device of FIG. 1 with and without a diode short circuit.
Figure 3 is a waveform diagram showing the operating characteristics at various points; Figure 3 is a plot diagram showing the voltage difference across the generator exciter windings over a range of normal load currents with and without a shorting diode; , FIG. 4 shows the locations of preset values in the microprocessor of the present invention, which are shown arranged between the short-circuit operating characteristics and non-short-circuit operating characteristics of FIG. 3. FIG. In the figure, 10 is a rotatable assembly (rotatable member), 11 is a field winding, 12 is a three-phase armature winding (a rotatable armature member), 13 is a rectifier assembly (rectifier device), 20 is a three-phase stator winding (fixed armature member), 26 is an alternator array (load current sensing device), 30 is a permanent magnet generator, 36 is an exciter field winding, 52 is a multiplexer, and 55 is a sensor 56 is a load current averaging circuit (load current sensing circuit device), 60 is a microprocessor device, and 65 is an output signal response device.

Claims (1)

[Claims] 1. A brushless alternator having a device for short-circuit diode protection that does not require the detection and use of field current or field current ripple, comprising: a fixed armature member; a rotatable member with a winding; a stationary member with a field winding; and an exciter having an armature member rotatable with the rotatable member of the generator; and a rectifier device for direct current excitation of the generator field winding, which is mounted on the exciter and is electrically connected between the armature member and the generator field winding in the exciter. , a device for supplying direct current to a field winding in said exciter; and a voltage difference across the field winding in said exciter having a predictable value over a range of normal generator load currents. a voltage difference sensing device that generates an output signal having a higher value when a short circuit occurs in a diode, the output signal having a higher value than the normal load current; an output signal response device that generates an output that cuts off the energization of the field winding in the exciter in response to the output signal when the range exceeds a preset value; AC generator. 2. The voltage difference sensing device is electrically coupled across a field winding in the exciter, and the multiplexer device included therein is
electrically coupled across a field winding in the exciter machine and to a microprocessor device included in the output signal response device, the multiplexer device 2. A brushless alternator as claimed in claim 1, adapted to accept signals from either side of a field winding in the machine and control signals from said microprocessor device. 3. The brushless alternating current generator of claim 2, wherein a load current sensing circuit arrangement included to be coupled to an output of the generator has an output coupled to the multiplexer arrangement. Machine.