JP4186880B2 - AC generator for vehicles - Google Patents

Description

  The present invention relates to a vehicular AC generator, and more particularly to a vehicular AC generator excellent in load dump surge absorption characteristics.

  When a battery terminal is disconnected due to engine vibration or when a high-power load is suddenly cut off in a generator of a vehicle charging system, the steepness of about several tens of microseconds is caused by the effect of the inductance of the armature winding and the current change. Armature winding became unloaded (substantially open) during a period of time when the pulse current of the generator and the stop of the field current of the generator decreased with a relatively long time constant of several hundred milliseconds This causes a sudden load reduction overvoltage. In this specification, the above two phenomena are referred to as load dump or load dump surge, and the armature voltage at this time is referred to as load dump surge voltage or load dump voltage. The time constant of the load dump voltage component related to the release of the stored magnetic energy of the former armature winding interlinkage magnetic circuit is much higher than the time constant until the increase in the no-load voltage is eliminated. small.

  It is desired to protect circuit elements and the like from this load dump voltage generated by the armature winding. In particular, in recent years, the electrical load for vehicles is increasing more and more, and countermeasures for load dumping due to the increase in the output voltage and output current of the AC generator for vehicles corresponding thereto are becoming important.

In view of this, in Patent Document 1, three diodes of one arm of a full-wave rectifier of a generator are configured by a constant voltage diode commonly called a Zener diode, or the constant voltage diode is connected in parallel with a full-wave rectifier. It is proposed to absorb the load dump voltage by providing it. Hereinafter, this method is abbreviated as a Zener type full-wave rectifier. In the following description, a Zener diode is synonymous with a diode having a constant voltage breakdown characteristic, that is, a constant voltage diode.
Japanese Patent No. 2751153

  When a load dump voltage is generated in a vehicle AC generator equipped with the above-described Zener type full-wave rectifier, heat generation corresponding to the breakdown voltage × current is generated in the Zener diode. For this reason, when the vehicular AC generator continues to progress in the direction of high power and high voltage as it is, the heat generated by the Zener diode exceeds the allowable heat generation. Specifically, there is a certain limit to the allowable maximum heat generation amount per unit time of a semiconductor chip, and in order to increase the allowable power loss, it is necessary to increase heat dissipation performance such as expansion of the chip area. is there.

  However, the increase in the chip area leads to an increase in the strain force due to the difference in thermal expansion coefficient between the semiconductor chip, the solder, and the electrode plates on both sides, which causes the problem that it exceeds the fatigue limit of the solder. In other words, in the state where the fatigue life limit of the solder is secured, there is a certain limit to the load dump surge absorption capability by the one-chip Zener diode, and the vehicle AC power generation that requires the load dump surge absorption performance exceeding this limit is required. It is impossible to increase the capacity of the machine. To avoid this problem, multiple Zener diodes must be connected in parallel, but the wiring, assembly, and structure of Zener-type full-wave rectifiers are complicated, including the need to match the variations in characteristics among the Zener diodes. The problem of becoming large is derived.

  In the Zener type full-wave rectifier described above, the temperature rises due to the forward voltage drop (about 1V) when the Zener diode is normally rectified by a large current, and the transient due to the Zener breakdown at the time of the load dump described above. Due to the temperature rise during load dump due to sudden increase in heat generation, the Zener breakdown voltage (having a positive characteristic with respect to temperature) becomes higher than the desired set voltage value (for example, less than 60 V, which is generally known as a safety voltage). Also, the problem that the load dumping suppression effect is lowered has occurred.

  In order to avoid the adverse effect of the decrease in the load dumping suppression effect due to the phenomenon of increasing the breakdown voltage of the Zener diode, it is conceivable to set a normal breakdown voltage value (when heat generation is not severe). In this case, however, the generator ripple voltage during normal power generation (the current pulsation caused by the wave superposition during three-phase rectification is added to the power supply voltage as voltage fluctuations due to wiring inductance and battery impedance) As a result, there is a possibility that the Zener diode will breakdown at each peak level of the high-frequency ripple voltage to generate a large amount of heat.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a high-power high-voltage vehicle AC generator that is excellent in economy and has excellent load dump surge absorption performance.

  A vehicle AC generator according to a first aspect of the present invention for solving the problem includes a rotating multipolar magnetic pole, a field winding for exciting the multipolar magnetic pole, and an armature core disposed to face the multipolar magnetic pole. And an armature winding having a first phase winding set and a second phase winding set each constituted by a plurality of phase windings and wound around the armature core, and the field winding, A vehicle AC comprising a field current control switching element connected in series to switch the field current, and a rectifier that rectifies the generated voltage of the armature winding and charges the vehicle battery to a predetermined charging voltage. In the generator, the rectifier includes a plurality of diodes each having a cathode connected to a positive electrode of the in-vehicle battery and an anode individually connected to an output terminal of each phase winding belonging to the first phase winding set. A diode set and an anode are in contact with the negative electrode of the vehicle battery. Each of the negative-polarity diode sets including a plurality of diodes individually connected to the output ends of the respective phase windings belonging to the second-phase winding set, and the cathodes belonging to the first-phase winding set. A buffer diode set composed of a plurality of diodes individually connected to the output ends of the phase windings and having an anode individually connected to the output ends of the phase windings belonging to the second phase winding set; Each diode of the positive electrode group and / or the negative electrode group is configured by a constant voltage diode having a breakdown voltage smaller than the voltage of the in-vehicle battery.

  The armature winding may further include a phase winding set in addition to the first phase winding set and the second phase winding set. A diode that is not a constant voltage diode may be replaced with a synchronous rectifying MOS transistor that is substantially equal to the rectifying operation of the diode.

  According to the present invention, the interphase surge voltage generated in the first phase winding set and the second phase winding set when a large power load is suddenly cut off is caused by the buffer diodes at the output terminals of both sets. In order to isolate | separate, since the surge voltage between phases is divided | segmented into the several group, it halves rather than the case where an armature winding is comprised by a single set of phase winding. Therefore, the breakdown voltage of the constant voltage diode (hereinafter also referred to as a Zener diode) constituting the positive diode group or the negative diode group is substantially halved compared to the conventional example in which the armature winding is configured by a single phase winding. As a result, the electrical resistance during forward energization of the Zener diode of the positive diode group or the negative diode group during normal rectification can be greatly reduced to reduce rectification loss, and further local concentration of current can be achieved. The prevention of the withstand voltage layer thickness reduction makes the manufacture of the Zener diode much easier. In addition, if the short-circuit current during load dump is constant, the chip heat generation per unit time during load dump can be halved by the reduction in breakdown voltage. Load dump can be absorbed.

In the first aspect of the invention, the phase winding of the first phase winding set and the phase winding of the second phase winding set are housed in different slots to generate voltages having different phases, and the rectifier Then, the generated voltage of the two-phase winding set is rectified, and the vector is added and output. When three-phase windings are employed as the first-phase winding group and the second-phase winding group, it is preferable that the phase voltages of both sets have a phase difference of an electrical angle π / 6.

  According to this configuration, the phase voltage output from each phase winding set is out of phase, so that the ripple of the voltage that is rectified and output is compared to the case where a conventional single three-phase winding set is used. Can be greatly reduced. This ripple reduction can have a positive effect on the vehicle power supply system such as an in-vehicle battery, and can further reduce the breakdown voltage of the Zener diode for absorbing the load dump.

  In a preferred aspect, each diode of only the positive diode group or the negative diode group is configured by a constant voltage diode having a breakdown voltage smaller than the voltage of the in-vehicle battery. In this way, the number of relatively expensive constant voltage diodes can be reduced. In this case, it seems that the load dump voltage on the side not constituted by the constant voltage diode, that is, the side constituted by the junction diode, of the positive diode group and the negative diode group cannot be reduced. Most of the magnetic fluxes to be exchanged are common, and the load dump voltage of the other phase winding set can be reduced by the magnetic energy consumption due to the breakdown of the constant voltage diode of one phase winding set. An excellent combined vector sum voltage suppression effect can be obtained at the output terminal, and a reduction in manufacturing cost can be realized.

  An automotive alternator according to a second aspect of the present invention that solves the above problems includes a rotating multipolar magnetic pole, a field winding that excites the multipolar magnetic pole, and an armature core that is disposed opposite to the multipolar magnetic pole, An armature winding having a first phase winding set and a second phase winding set each constituted by a plurality of phase windings and wound around the armature core, and series connection with the field winding AC current generator comprising: a field current control switching element that switches the field current and a rectifier that rectifies the generated voltage of the armature winding and charges the vehicle battery to a predetermined charging voltage. The positive rectifier comprises a plurality of diodes each having a cathode connected to a positive electrode of the in-vehicle battery and an anode individually connected to an output terminal of each phase winding belonging to the first phase winding set. And the anode is connected to the negative electrode of the vehicle battery A negative diode group comprising a plurality of diodes individually connected to an output end of each phase winding belonging to the second phase winding group, and each phase belonging to the first phase winding group A buffer diode set consisting of a plurality of diodes individually connected to the output ends of the windings and having an anode individually connected to the output ends of the phase windings belonging to the second phase winding set; It consists of a plurality of diodes that are individually connected to the output ends of the respective phase windings of the one-phase winding group or the second-phase winding group and apply a rectified voltage for energizing a field current to the field winding. A constant voltage diode having a diode group for excitation, the diode of the diode group for excitation being smaller than the voltage of the in-vehicle battery, and having a breakdown voltage equal to or lower than the withstand voltage of the diodes of the positive electrode group and the negative electrode group It is characterized by being more configurations.

  The armature winding may further include a phase winding set in addition to the first phase winding set and the second phase winding set. A diode that is not a constant voltage diode may be replaced with a synchronous rectifying MOS transistor that is substantially equal to the rectifying operation of the diode.

  According to the present invention, it is possible to obtain an excellent effect that the breakdown voltage and the temperature rise of the load dump absorbing constant voltage diode can be greatly reduced. That is, since only a small field current that is less than 1/10 of the main generated current flows during normal power generation in the exciting diode group, the constant voltage diodes that constitute the exciting diode group have the same chip area. Compared to the positive voltage diode group or negative voltage diode group constant voltage diode (conventional example), the temperature rise during normal power generation is much smaller, so there is room for the temperature increase of the constant voltage diode of the excitation diode group during load dump energy absorption That is, the instantaneous load dump current carrying capacity and heat generation capacity are remarkably large. Therefore, it is possible to satisfactorily prevent deterioration and breakage due to temperature rise when absorbing a load dump of a small constant voltage diode.

  Further, in the present invention, when the exciting diode group is broken down, only the phase winding group to which the exciting diode group is connected is short-circuited, and the constant voltage diode (zener diode) of the exciting diode group No vector-added load dump voltage is applied to the two-phase winding set. Therefore, a Zener diode having a low breakdown voltage, a low forward power loss and a large allowable load dump current value can be manufactured at a low cost. Furthermore, since the temperature rise is small, the breakdown voltage fluctuation due to the temperature rise can be suppressed, and the surge voltage can be surely suppressed below the desired safe voltage.

  In a preferred aspect, the rectifier is configured such that an anode is individually connected to an output terminal of each phase winding of the first phase winding set, and a rectification voltage for energizing a field current is applied to the field winding. It has a pair of exciting diodes consisting of a plurality of diodes, and both ends of the field winding are in a flywheel circuit in which a junction diode and a constant voltage diode are connected in series with anodes or cathodes connected to each other. It is connected.

  In this way, the magnetic energy dissipation of the field circuit can be performed by the breakdown of the constant voltage diode (also called the flywheel Zener diode) of the flywheel circuit, reducing the time constant of the load dump surge voltage and Heat generation of each diode due to dumping can be reduced.

  In a preferred aspect, the positive diode and the negative diode are configured by a constant voltage diode having a breakdown voltage that is higher than the constant voltage diode of the exciting diode set and is 30 V or less.

  With this configuration, the exciting diode set with high thermal resistance and excellent load dump energy absorption absorbs the surge power on the peak wave in the most severe load dump early stage. Even if a normal junction diode is used as the group or the negative electrode diode group, the load dump voltage can be kept within an allowable range, and the total manufacturing cost of the rectifier can be reduced as a whole. In addition, since the diodes of the positive diode group and the negative diode group can be designed ignoring the load dump absorption performance, the fatigue life can be improved.

In a preferred aspect, each of the first phase winding group and the second phase winding group includes two phase windings having phases different from each other by π / 2, and the phase winding of the first phase winding group The phase of the wire and the phase winding of the second phase winding set is different from each other by π / 4. In this way, the above-described effect can be realized by the same number of rectifier diodes as that of the conventional single-stage three-phase full-wave rectifier, and the armature windings are different slots adjacent to each other in, for example, distributed windings. Since the electrical angle between them can be π / 2, the rotating magnetic field caused by the armature current can be smoothly rotated, so that fluctuations in torque ripple and magnetic noise can be reduced.
(Modification)
The diodes of the positive diode group or the negative diode group described above can be configured by MOS transistors that are turned on when a load dump occurs. In this way, the load dump energy can be extinguished by turning on all the MOS transistors of the positive diode group or the negative diode group when the load dump occurs.

  In this case, the on-resistance of the MOS transistor is much smaller than the breakdown resistance of the Zener diode with respect to the electric resistance of the armature winding, so that the load dump energy is mainly consumed by the armature winding, and therefore the load is as a MOS transistor. It is not necessary to increase the size in consideration of dump absorption.

  A preferred embodiment of the vehicle alternator of the present invention will be described below. However, the present invention is not limited to the examples described below, and it is obvious that the technical idea of the present invention may be implemented in combination with other known techniques or equivalent techniques.

(First embodiment)
The main part of the vehicle alternator of the first embodiment will be described with reference to the circuit diagram shown in FIG.

(Configuration of armature winding)
Reference numeral 1 denotes a field rotor core (also referred to as a rotor field) which is a Landel claw-shaped soft magnetic core having 16 unillustrated multipolar magnetic poles (rotating multipolar magnetic poles). Reference numeral 2 denotes an armature core disposed opposite to the multipolar magnetic poles of the rotor field 1 and is formed by laminating thin electromagnetic steel sheets having a thickness of about 0.35 mm. An armature winding 3 is wound around the armature core 2.

  More specifically, the armature core 2 has 6 slots per magnetic pole, for a total of 96 slots, and four odd-numbered slots are inserted with four conductors of the same phase, and these four conductors of the same phase have six slots. Winding is reversed for each pitch. The four in-phase conductors inserted in these odd-numbered slots constitute a first Y-connected three-phase winding set composed of U, V, and W phase windings 4, 5, and 6.

  Similarly, four conductors having the same phase are inserted into each even-numbered slot, and these four conductors having the same phase are wound with their directions reversed every six slot pitches. The four in-phase conductors inserted in these odd-numbered slots constitute a second Y-connected three-phase winding composed of X, Y, and Z-phase windings 7, 8, and 9. Therefore, the armature winding 3 is constituted by these two Y-connected three-phase windings, and the X, Y, Z-phase windings 7, 8, 9 and the U, V, W-phase windings 4, 5, 6 Have different phases by 1 slot pitch, that is, electrical angle π / 6 in the circumferential direction.

(Rectifier configuration)
The U, V, and W phase windings 4, 5, and 6 are anodes of positive Zener diodes A, B, and C (that are also referred to as positive Zener diodes 10, 11, and 12) that are Zener diodes having a breakdown voltage of 29 V, As shown in FIG. 1, they are individually connected to the cathodes of buffer diodes 13, 14, and 15 made of PN junction diodes. The X, Y, and Z phase windings 7, 8, and 9 also include cathodes of negative zener diodes A, B, and C (also referred to as negative zener diodes 16, 17, and 18) that are zener diodes having a breakdown voltage of 29 V , 14 and 15 are individually connected as shown in FIG.

  The generated voltages of the U, V, W phase windings 4, 5, 6 and the X, Y, Z phase windings 7, 8, 9 are rectified by a rectifier circuit called a three-level rectifier 19 in this specification. The cathode of the positive zener diode is connected to the high potential end of the electric load 21 and the positive electrode of the in-vehicle battery 22 through the output terminal 20, the anode of the negative zener diodes 16, 17, 18, the low potential end of the electric load 21, and the in-vehicle battery 22. The negative electrode is installed.

(Regulator configuration)
The regulator 23 connects the low potential end of the field winding 28 and the grounding body to control the current of the field winding 28 intermittently and the voltage at the output terminal 20 of the generator. An overvoltage detection circuit unit 25 that is an inverting output type comparator that compares with a predetermined threshold voltage, and a battery charge voltage detection circuit that is an inverting output type comparator that compares the positive potential of the on-vehicle battery 22 with a predetermined threshold voltage. Part 26 and a field cutoff interrupt circuit part 27 which is an AND circuit for making a field voltage cutoff interrupt. The switching transistor 24 becomes high when both the voltage at the output terminal 20 of the generator and the positive potential of the in-vehicle battery 22 are lower than the respective threshold voltages, and turns on the switching transistor 24. A field current is passed through the magnetic winding 28.

(Configuration of field circuit)
Approximately 500 turns of the field winding 28 are wound around the rotor field 1. The cathode of a flywheel diode 29 which is a pn junction diode is connected to the high potential end of the field winding 28. The anode of the flywheel diode 29 is connected to the anode of a flywheel Zener diode 30 that is a Zener diode, and the cathode of the flywheel Zener diode 30 is connected to the low potential end of the field winding 28. The low potential end of the field winding 28 is connected to the collector electrode of the switching transistor 24 having a common emitter. The breakdown voltage of the flywheel Zener diode 30 is set smaller than the generator steady output voltage and larger than the forward voltage drop of the flywheel diode 29. The flywheel diode 29 and the flywheel zener diode 30 constitute a so-called flywheel circuit.

  The U, V, and W phase windings 4, 5, and 6 are connected to the anodes of the Zener diodes 31, 32, and 33 constituting the exciting Zener diode trio, and the cathodes of the Zener diodes 31, 32, and 33 are field windings. 28 is connected to the high potential end. The breakdown voltages of the Zener diodes 31, 32, 33 are set smaller than the breakdown voltages of the positive Zener diodes 10, 11, 12 and the negative Zener diodes 16, 17, 18 and smaller than the voltage of the in-vehicle battery 22. The chip current density of the Zener diodes 31, 32, 33 in normal power generation rectification use is the allowable rated chip current density of the self or the rated chip current during rectification of the positive Zener diodes 10, 11, 12 and the negative Zener diodes 16, 17, 18. The density is set to 1/5 or less, more preferably 1/10 or less.

(Operation explanation during normal power generation)
The operation of the above-described vehicle alternator during normal power generation will be described below.

  The rotor field 1 generates an initial field flux by a residual magnetic flux or a field winding 28 energized from an initial excitation circuit in a regulator (not shown). When the rotor field 1 is driven by a generator drive shaft (not shown), a rotating magnetic field is generated in the armature core 2, and a first three-phase winding composed of U, V, and W phase windings 4, 5, and 6; Three-phase voltages having different phases are generated in the second three-phase winding composed of the X, Y, and Z-phase windings 7, 8, and 9. In this embodiment, as shown in FIG. 1, the winding directions of the U, V, W phase windings 4, 5, 6 and the X, Y, Z phase windings 7, 8, 9 are reversed. The U-phase winding 4 and the X-phase winding 7 are different in phase angle by an electrical angle of 5π / 6 or 7π / 6. That is, the U-phase voltage output from the U-phase winding 4 after π / 6 after the X-phase voltage output from the X-phase winding 7 becomes the maximum positive voltage becomes the negative maximum voltage.

  The flow of the armature current will be described.

  The U-phase voltage output from the U-phase winding 4 is larger in the negative direction than the V and W-phase voltages output from the V and W-phase windings 5 and 6, and the X-phase voltage output from the X-phase winding 7 is Output from the neutral point of the X, Y, Z phase windings 7, 8, 9 through the phase winding 7 in a period larger in the positive direction than the Y, Z phase voltages output by the Y, Z phase windings 8, 9 The generated current is diode 13, U phase winding 4, V, W phase windings 5, 6, positive zener diodes 11, 12, in-vehicle battery 22, grounding body, negative zener diodes 17, 18, V, W phase winding. It flows in the order of the neutral points of the wires 5, 6, X, Y, and Z-phase windings 7, 8, and 9. In the other phase periods, current flows in the same manner.

  That is, the three-level rectifier 19 rectifies and outputs a combined voltage obtained by adding the voltages of two three-phase windings as a vector. Therefore, the output terminal 20 of the three-level rectifier 19 can output a rectified output voltage with less ripple than a normal vehicle AC generator using one three-phase full-wave rectifier.

  When the in-vehicle battery 22 is charged and the battery voltage rises, the battery charge voltage detection circuit unit 26 applies a low-level potential to the switching transistor 24 to cut off the field current. A high-level potential is applied to the transistor 24 to start energizing the field current.

(Explanation when a load dump occurs)
If a problem such as disconnection of the terminal of the in-vehicle battery 22 occurs for some reason while the generator is supplying output to the load, the load suddenly comes off even though the field winding 28 is excited ( Therefore, the generator is in an unloaded open power generation state or a state close thereto, and the generator output terminal voltage rises rapidly.

  When this sudden rise occurs, the overvoltage detection circuit 25 outputs a low level potential to the field cutoff interrupt circuit unit 27, so that the field cutoff interrupt circuit unit 27 outputs a low level potential to the base electrode of the switching transistor. Cut off the magnetic current. However, since the field winding 28 has a large time constant of several hundred milliseconds, the field magnetic flux cannot be reduced suddenly, and a flywheel current is caused to flow through the flywheel circuit. Since this flywheel current causes a large loss when flowing through the flywheel Zener diode 30, the field energy can be quickly dissipated, thereby shortening the field time constant, which is the time constant of the field flux reduction curve. Is done. However, even if the field time constant is shortened as described above, the generator armature winding terminal is generated by the field magnetic flux due to the flywheel current until a predetermined time specified by the field time constant after the load dump occurs. In this case, a load dump surge voltage close to a no-load open circuit voltage is generated.

  In order to cope with this problem, in this embodiment, the breakdown voltage of the Zener diodes 31, 32, 33 is lower than the voltage of the in-vehicle battery 22 as described above, and the positive Zener diodes 10, 11, 12 and the negative Zener diode are used. It is set lower than the breakdown voltages of 16, 17, and 18. Therefore, the load dump voltage generated in the armature winding 3 is preferentially absorbed by the Zener diodes 31, 32 and 33.

  The load dump energy absorption operation by the Zener diodes 31, 32, 33 will be described in more detail with reference to the explanatory diagram shown in FIG.

  When the interphase voltage of the U, V, W phase windings 4, 5, 6 exceeds the breakdown voltage of the Zener diodes 31, 32, 33, the breakdown Zener diodes U, U, Magnetic energy stored in armature inductance by forming a short circuit composed of at least two phase windings of V, W phase windings 4, 5 and 6 connected in series with each other and a Zener diode conducting in the forward direction. Is consumed by the electrical resistance of the phase winding and the voltage drop of the broken Zener diode, and rapidly decays, and the phase voltages of the U, V, and W phase windings 4, 5, and 6 decay rapidly. Since the U, V, W phase windings 4, 5, 6 and the X, Y, Z phase windings 7, 8, 9 are linked to a substantially common magnetic circuit, the X, Y, Z phase windings The magnetic energy accumulated in the inductances of 7, 8, and 9 is electromagnetically released to the U, V, and W phase windings 4, 5, and 6, and the respective phases of the X, Y, and Z phase windings 7, 8, and 9 are released. The voltage also decreases rapidly.

  Therefore, in this embodiment, since the load dump energy is absorbed by the Zener diodes 31, 32, 33, either or both of the positive Zener diodes 10, 11, 12 and the negative Zener diodes 16, 17, 18 are joined to each other. Alternatively, it can be configured by a MOS transistor that is synchronously rectified.

  Next, consider a case where the load dump energy is further large and the positive Zener diodes 10, 11, 12 or the negative Zener diodes 16, 17, 18 break down. Between the two Zener diodes of the positive Zener diodes 10, 11, and 12, the interphase voltage of the U, V, and W phase windings 4, 5, and 6 is applied. When the breakdown voltage of 10, 11, 12 is exceeded, one of the positive Zener diodes 10, 11, 12 breaks down and a short circuit is formed. Similarly, since the interphase voltage of the X, Y, Z phase windings 7, 8, 9 is applied between two of the negative zener diodes 16, 17, and 18, the interphase voltage is negative. When the breakdown voltage of the Zener diodes 16, 17, 18 is exceeded, one of the negative Zener diodes 16, 17, 18 breaks down, forming a short circuit.

  Also in this case, the positive Zener diodes 10, 11, 12 and the negative Zener diodes 16, 17, 18 have voltages of U, V, W phase windings 4, 5, 6 and X, Y, Z phase windings 7, Since the combined vector sum voltage with the voltages of 8 and 9 is not applied but the interphase voltage of the three-phase winding is applied, the breakdown voltage of the Zener diode can be greatly reduced. Even when only the positive Zener diodes 10, 11, and 12 are used as Zener diodes to absorb the load dump, the load dump voltage of the X, Y, and Z phase windings 7, 8, and 9 is attenuated by this absorption. Any one of the Zener diodes 10, 11, 12 and the negative Zener diodes 16, 17, 18 may be used as a Zener diode. That is, since the armature winding is divided into two three-phase windings, as shown in FIG. 2, the positive Zener diodes 10, 11, 12 and the negative Zener diodes 16, 17 are the same as the excitation Zener diode trio. , 18 is half of the conventional Zener type full-wave rectifier shown in FIG. 6, the energy to be dissipated by the Zener diode can be reduced.

  However, in any case, it is preferable to breakdown the Zener diodes 31, 32, and 33 of the exciting diode set with priority. This is because the Zener diodes 31, 32, 33 are only supplied with a field current during normal power generation, and therefore have the same chip size as the positive Zener diodes 10, 11, 12 and the negative Zener diodes 16, 17, 18. If so, the chip current density is about 1/10. Therefore, the Zener diodes 31, 32, and 33 have a load dump surge current absorption capability that is significantly larger than that of the positive Zener diodes 10, 11, and 12 and the negative Zener diodes 16, 17, and 18.

(Experimental result)
As shown in FIG. 6, in a conventional high-power high-voltage generator with a maximum rated output of 3.5 kW and 42 V, a load dump with a tip diameter of 12 mm and a breakdown voltage of 70 V is 6 and the load dump is 70 V. Voltage suppression was performed. On the other hand, in this embodiment shown in FIG. 1, in a high-power high-voltage generator with a maximum rated output of 5 kW and 42 V, the Zener diodes 3, 32 and 33 have a chip diameter of 12 mm and a breakdown voltage of 27 V. The positive zener diodes 10, 11, 12 and the negative zener diodes 16, 17, 18 are junction diodes similar to the buffer diodes 13, 14, 15. Thereby, absorption of the surge voltage of 58V was able to be achieved.

(Modification)
The exciting Zener diode trio may be provided not on the U, V, W phase windings 4, 5, 6 side but on the X, Y, Z phase windings 7, 8, 9 side.

(Example effect)
After all, in this embodiment, the exciting diode trio that rectifies and outputs the U, V, W phase windings 4, 5, 6 of the three-level rectifier 19 to the field winding 28 from each output terminal of the first three-phase winding. Is composed of Zener diodes 31, 32, 33, and the load dump energy is attenuated by short-circuiting the U, V, W phase windings 4, 5, 6 due to breakdown of the Zener diodes 31, 32, 33. The effect of can be produced.

  That is, according to this embodiment, the Zener diodes 31, 32, 33 do not short-circuit the entire armature winding due to breakdown, but short-circuit the U, V, W-phase windings 4, 5, 6; The interphase voltages of the U, V, and W phase windings 4, 5, and 6 are applied to the diodes 31, 32, and 33, and the breakdown voltage of the Zener diodes 31, 32, and 33 and the amount of generated heat per unit time are set. The effect that it can be halved can be produced. Therefore, the temperature rise of the Zener diodes 31, 32, 33 themselves can be reduced while preventing the load dump voltage from exceeding the dangerous level due to the breakdown of the Zener diodes 31, 32, 33. Of course, the decrease in the amount of heat generated per unit time of the Zener diodes 31, 32, 33 delays the decay of the load dump energy, and the Zener diodes 31, 32, 33 are increased by increasing the load dump current energizing time. However, the resistance reduction effect at the breakdown of the Zener diodes 31, 32, and 33 is more effective for suppressing the temperature increase of the Zener diodes 31, 32, and 33 than this tendency. .

  In addition, since the three-level rectifier 19 is employed, the solder fatigue life can be extended due to the advantage that the ripple of the rectified output voltage can be reduced to about ¼, and the temperature rise of the Zener diodes 31, 32, 33 can be reduced.

(Modification)
In FIG. 1, Zener diodes 31, 32, and 33 that form a pair of exciting diodes are junction diodes, and a load dump is absorbed by one or both of positive Zener diodes 10, 11, and 12 and negative Zener diodes 16, 17, and 18. You can also

(Second embodiment)
The vehicle alternator of the second embodiment will be described below with reference to FIGS.

  In the first embodiment described above, Zener diodes 31, 32, 33 are used for the Zener diode trio for excitation, and Zener diodes are used for the positive Zener diodes 10, 11, 12 and the negative Zener diodes 16, 17, 18. It was. In contrast, in the second embodiment, the positive zener diodes 10, 11, 12 and the negative zener diodes 16, 17, 18 are junction diodes. The breakdown voltage of the exciting zener diode trio is set to 27V.

  Further, in this embodiment, the U, V, W phase windings 4, 5, 6 and the X, Y, Z phase windings 7, 8, 9 are in phase (however, the winding directions are reversed as shown in FIG. 3). ). The voltage waveform of this embodiment is shown in FIG.

  Thereby, the effect similar to 1st Example can be acquired. That is, since the current density during normal power generation of the Zener diodes 31, 32, 33 is small, the temperature characteristics need not be considered, and the total integrated current value at the beginning of breakdown can be greatly competed, and the breakdown voltage is set low. As a result, the advantages of being easy to manufacture and well withstanding large currents can be obtained.

  In addition, since the U, V, W phase windings 4, 5, 6 and the X, Y, Z phase windings 7, 8, 9 are in phase, instead of expecting the ripple reduction effect, the armature The number of slots in which the windings are to be accommodated can be reduced, and the effect that a large voltage can be generated with the same number of turns can be achieved.

(Modification)
In the second embodiment, both the positive zener diodes 10, 11, 12 and the negative zener diodes 16, 17, 18 of the three-level rectifier 19 are junction diodes. However, the positive zener diodes 10, 11, 12 and the negative zener Only one of the diodes 16, 17, and 18 may be configured using a junction diode.

(Third embodiment)
The vehicle alternator of the third embodiment will be described below with reference to FIG.

  In this embodiment, the armature winding is constituted by a first phase winding set 31 and a second phase winding set 32. The first phase winding set 31 is configured by only the A phase winding, and the second phase winding set 32 is configured by only the B phase winding. The A and B phase windings differ from each other in electrical angle by π / 2. This type of armature winding is known as a so-called two-phase winding, and can be easily wound and the coil end can be reduced.

  In each slot of the armature core 2, the conductors constituting each winding are arranged in the circumferential direction so as to be separated by π / 2 in the order of A, B, -A, -B, A.

  The essential difference between the circuit of FIG. 5 and the circuit of FIG. 1 is that, in addition to the buffer diodes 13 and 14, the buffer diode 13 ′ and the buffer diode 14 ′ are arranged in a stroke, and the negative diode set The diodes 16 and 17 are junction diodes.

  When a load dump occurs, the load dump energy is converted into heat by the AY phase winding 31 due to a short circuit due to the breakdown of either one of the Zener diodes 31 and 32 or 10 or 11.

  Either the set of the Zener diodes 31 and 32 or the set of the Zener diodes 10 and 11 may be a junction diode. The Zener diodes 10 and 11 may be junction diodes, and the junction diodes 16 and 17 may be Zener diodes.

  According to this embodiment, the circuit configuration of the winding and the rectifier can be simplified while ensuring the smooth rotation of the rotating current magnetic field, which is excellent in practicality. Although four buffer diodes are required, the average amount of current flowing through one buffer diode is reduced by that amount, and the chip size can be reduced, so that an increase in cost can be suppressed.

It is a circuit diagram of the AC generator for vehicles of the 1st example. FIG. 2 is an operation explanatory diagram of the vehicle AC generator of FIG. 1. It is a circuit diagram of the AC generator for vehicles of the 2nd example. It is operation | movement explanatory drawing of the alternating current generator for vehicles of 2nd Example. It is operation | movement explanatory drawing of the alternating current generator for vehicles of 3rd Example. It is operation | movement explanatory drawing of the alternating current generator for vehicles of a prior art.

Explanation of symbols

1 ... Rotor field (multipole magnetic pole)
2 ... Armature core 3 ... Armature winding 4 ... U phase winding (phase winding of the first phase winding set)
5 ... V phase winding (phase winding of the first phase winding set)
6 ... W phase winding (phase winding of the first phase winding set)
7 ... X phase winding (phase winding of second phase winding set)
8 ... Y phase winding (phase winding of second phase winding set)
9 ... Z phase winding (phase winding of the second phase winding set)
10 ... Positive Zener Diode A (Positive Diode Set Diode)
11: Positive Zener Diode B (diode of positive diode group)
12 ... Positive Zener Diode C (Positive Diode Set Diode)
13 ... Buffer diode A (diode of buffer diode set)
14... Buffer diode B (Diode of buffer diode set)
15... Buffer diode C (Diode of buffer diode set)
16: Negative zener diode A (diode of negative diode group)
17... Negative zener diode B (diode of negative electrode set)
18... Negative Zener Diode C (Negative Diode Set Diode)
19 ... Three-level rectifier 20 ... Output terminal 21 ... Electric load 22 ... In-vehicle battery 23 ... Regulator (field current regulator)
24 ... switching transistor 25 ... overvoltage detection circuit unit 26 ... battery charging voltage detection circuit unit 27 ... field cutoff interrupt circuit unit 28 ... field winding 29 ... flywheel diode 30 ... Flywheel Zener Diode 31 ... Excited Zener Diode A
32 ... Excited Zener diode B
33 ... Excited Zener diode C

Claims (4)

A rotating multipole magnetic pole,
A field winding for exciting the multipole magnetic pole;
An armature core disposed opposite to the multipole magnetic pole;
An armature winding wound around the armature core having a first phase winding set and a second phase winding set respectively constituted by a plurality of phase windings;
A switching element for field current control connected in series with the field winding to switch the field current;
A rectifier that rectifies the generated voltage of the armature winding and charges the on-vehicle battery to a predetermined charging voltage;
In a vehicle alternator comprising:
The rectifier is
A positive diode set comprising a plurality of diodes each having a cathode connected to the positive electrode of the in-vehicle battery and an anode individually connected to an output end of each phase winding belonging to the first phase winding set;
A negative diode set comprising a plurality of diodes each having an anode connected to the negative electrode of the in-vehicle battery and a cathode individually connected to an output terminal of each phase winding belonging to the second phase winding set;
A cathode is individually connected to an output end of each phase winding belonging to the first phase winding set, and an anode is individually connected to an output end of each phase winding belonging to the second phase winding set. A buffer diode set consisting of a plurality of diodes;
Have
Each diode of the positive diode group and / or the negative diode group,
It is composed of a constant voltage diode having a breakdown voltage smaller than the voltage of the vehicle battery ,
Is accommodated in different slots than the previous SL the first phase winding sets of phase windings second phase winding sets of phase windings to power the different phases of the voltages with each other,
The vehicle rectifier rectifies the generated voltage of the two-phase winding set, adds the vector, and outputs the rectifier . A rotating multipole magnetic pole,
A field winding for exciting the multipole magnetic pole;
An armature core disposed opposite to the multipole magnetic pole;
An armature winding wound around the armature core having a first phase winding set and a second phase winding set respectively constituted by a plurality of phase windings;
A switching element for field current control connected in series with the field winding to switch the field current;
A rectifier that rectifies the generated voltage of the armature winding and charges the on-vehicle battery to a predetermined charging voltage;
In a vehicle alternator comprising:
The rectifier is
A positive diode set comprising a plurality of diodes each having a cathode connected to the positive electrode of the in-vehicle battery and an anode individually connected to an output end of each phase winding belonging to the first phase winding set;
A negative diode set comprising a plurality of diodes each having an anode connected to the negative electrode of the in-vehicle battery and a cathode individually connected to an output terminal of each phase winding belonging to the second phase winding set;
A cathode is individually connected to an output end of each phase winding belonging to the first phase winding set, and an anode is individually connected to an output end of each phase winding belonging to the second phase winding set. A buffer diode set consisting of a plurality of diodes;
A plurality of anodes are individually connected to the output ends of the respective phase windings of the first phase winding group or the second phase winding group to apply a rectified voltage for applying a field current to the field winding. Having a pair of exciting diodes consisting of
The diode of the exciting diode set is:
An automotive alternator comprising a constant voltage diode having a breakdown voltage lower than a voltage of the on-vehicle battery and having a breakdown voltage equal to or lower than a withstand voltage of the diodes of the positive diode group and the negative diode group. In the vehicle alternator according to claim 1 or 2 ,
The rectifier is
An exciting diode set comprising a plurality of diodes each having an anode connected individually to an output end of each phase winding of the first phase winding set and applying a rectified voltage for energizing a field current to the field winding Have
Both ends of the field winding are
An automotive alternator characterized in that it is connected to a flywheel circuit in which a junction diode and a constant voltage diode are connected in series in a state where the anodes or the cathodes are connected. In the vehicle alternator according to claim 2 or 3 ,
The positive diode and the negative diode are:
An automotive alternator comprising a constant voltage diode having a breakdown voltage higher than that of the excitation diode set and having a breakdown voltage of 30 V or less.

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