Title of Invention

OUTPUT CONTROL UNIT FOR SYNCHRONOUS GENERATOR

Abstract

1. An output control unit for a synchronous generator (1) having a rotor (60) provided with field flux generating magnet means (62) and a stator (50) with stator windings thereon for producing a generated output, comprising: detector means (30) for detecting the number of revolutions of said rotor (60); energizing means (46) for, when the number of revolutions of said rotor is in a low revolution region, retard-energizing said stator windings to increase a generated energy of the generator so as to control an output voltage of the generator to be a voltage control value which is set lower than a regulating voltage; and a regulator (5) for restricting an output voltage of the generator to a regulating voltage, wherein said retard-energizing is performed when the number of revolutions of said rotor (60) lies in a low revolutions region and it is performed so as to control said output voltage to a predetermined voltage control value lower than said regulating voltage.

Full Text

FORM 2 THE PATENTS ACT, 1970 [39 OF 1970] 8B THE PATENTS RULES, 2003 COMPLETE SPECIFICATION [See Section 10; rule 13] "OUTPUT CONTROL UNIT FOR SYNCHRONOUS GENERATOR" HONDA GIKEN KOGYO KABUSHIKI KAISHA, of 1-1, Minamiaoyama 2-chome, Minato-ku, Tokyo, Japan, The following specification particularly describes the nature of the invention and the manner in which it is to be performed:- GRANTED 4-7-2008 ORIGINAL 4 JUL 2005 DESCRIPTION Technical Field The present invention relates to an output control unit for a synchronous motor and more particularly to an output control unit for a synchronous motor suitable for increasing a generated energy in a low revolution region. Background Art As a vehicular generator there is used a three-phase synchronous generator and an alternating current generated thereby is rectified by a three-phase full wave rectifier for use in charging a battery. In a three-phase synchronous generator disclosed in Japanese Patent Laid Open No. 19194/1997, a phase-advancing current is allowed to flow in stator coils and a field flux is increased to increase an output (generated voltage and output current) by virtue of magnetization based on armature reaction which is caused by the phase-advancing current. Generally, a generator is provided with a regulator which restricts an output voltage so as to prevent a generated output from exceeding a predetermined value. The generation of electric power is stopped by functioning of the regulator. When the power generation stops, there occurs a load variation in an engine, so that the engine revolution becomes unstable particularly in a low revolution region. Moreover, if the generated output is too large, the resulting increase of friction in a low revolution region greatly influences the engine revolution. It is an object of the present invention to provide an output control unit for a synchronous generator capable of increasing a generated output without making the revolution of an engine unstable in a low revolution region. Disclosure of Invention For achieving the above-mentioned object, the present invention is firstly characterized by an output control unit for a synchronous generator, comprising detector means for detecting the number of revolutions of a rotor of the generator, energizing means for retard-energizing stator windings to increase a generated energy of the generator, and a regulator for restricting an output voltage of the generator to a regulating voltage, wherein the retard- energizing is performed when the number of revolutions of the rotor lies in a low revolution region and it is performed so as to control the output voltage to a predetermined voltage control value lower than the regulating voltage. According to this first feature, the generated output is increased by retard-energizing the stator windings. Since this retard-energizing is performed so as to control the output voltage to a voltage control value which is set lower than the regulating voltage of the regulator, the generated energy can be increased stably without operating the regulator in a low revolution region. The present invention is secondly characterized in that, in the retard-energizing, the output voltage is controlled to the predetermined voltage control value by changing an energizing duty while maintaining an energizing retard quantity at a predetermined value. The present invention is thirdly characterized in that the voltage control value has a predetermined range and the energizing duty is slightly decreased upon arrival of the output voltage at a maximum in the range and is slightly increased upon drop of the output voltage to a value of not larger than a minimum value in the range. Further, the present invention is fourthly characterized in that the energizing duty is determined in accordance with the number of revolutions of the generator. According to the second to fourth features, since the retard timing is fixed, it is easy to adjust the generated energy and the adjustment accuracy can be enhanced. Brief Description offDrawings Fig. 1 is a block diagram showing functions of principal portions in an output control unit according to an embodiment of the present invention; Fig. 2 is a sectional view of a combined starter/generator related to the embodiment; Fig. 3 is a principal electric appliances system diagram of a two-wheeled motor vehicle having the output control unit embodying the present invention; Fig. 4 illustrates a relation between the engine speed and a generated electric current in ACG energizing control; Fig. 5 illustrates a change in battery voltage in a retard power generation region; Fig. 6 is a flow chart showing processings executed by the output control unit; Fig. 7 illustrates a timing between phase currents flowing in stator coils and outputs of rotor angle sensors in ACG energizing control; and Fig. 8 is an energizing duty table using the engine speed as a parameter. Best Mode for Embodying the Invention An embodiment of the present invention will now be described with reference to the drawings. Fig. 2 is a sectional view of a combined starter/generator related to an embodiment of the present invention. The combined starter/generator (hereinafter referred to as "ACG"), indicated at 1, is mounted, for example, on an engine of a scooter type two-wheeled motor vehicle. The ACG 1 has a stator 50 with three-phase windings (stator coils) thereon and an outer rotor 60 connected to an end portion of a crank shaft 201 of an engine and adapted to rotate along an outer periphery of the stator 50. The outer rotor 60 has a cup-shaped rotor case 63 connected to the crank shaft 201 and magnets 62 which are disposed on an inner periphery surface of the rotor case 63 in a circumferential direction of a rotor yoke. The outer rotor 60 is mounted by fitting an inner periphery of a hub portion 60a onto a tapered front end portion of the crank shaft 201 and is fixed with a bolt 253 which is inserted through the center of the hub portion 60a into a threaded hole in the end portion of the crank shaft 201. The stator 50, which is disposed on an inner periphery side of the outer rotor 60, is fixed to a crank case 202 with bolts 279. Further, a fan 280 is fixed to the outer rotor 60 with bolts 246. Adjacent the fan 280 is a radiator 282, which is covered with a fan cover 281. A sensor case 28 is fitted in an inner periphery of the stator 50. Within the sensor case 28 are provided rotor angle sensors (magnetic pole sensors) 29 and a pulser sensor (ignition pulser) 30 at equal intervals along an outer periphery of a boss of the outer rotor 60. The rotor angle sensors 29 are for energizing-control for the stator coils of the ACG 1 and three such rotor angle sensor 29 are provided correspondingly to U, V, and W phases, respectively, of the ACG. On the other hand, the ignition pulser 30 is for ignition control for the engine and only-one such ignition pulser 30 is provided. The rotor angle sensors 29 and the ignition pulser 30 can each be constituted by a Hall IC or a magnetic reluctance (MR) element. Lead wires of the rotor angle sensors 29 and the ignition pulser 30 are connected to a substrate 31 and a wire harness 32 is connected to the substrate 31. A magnet ring 33 is fitted on an outer periphery of the boss 60a of the outer rotor 60, the magnet ring 33 being magnetized in two stages so as to exert a magnetic action to each of the rotor angle sensors 29 and the ignition pulser 30. In one magnetized zone of the magnet ring 33 corresponding to the rotor angle sensors 29 are formed N and S poles alternately at 30° intervals in the circumferential direction correspondingly to the magnetic poles of the stator 50. In the other magnetized zone of the magnet ring 33 corresponding to the ignition pulser 30 there is formed one magnetized portion circumferentially in the range of 15° to 40° . The ACG 1 constructed as above functions as a synchronous motor at the time of starting and is driven with an electric current fed from a battery, causing the crank shaft 201 to rotate and thereby causing the engine to start. After start-up of the engine the ACG 1 functions as a synchronous generator, charges the battery with generated electric current and supplies the electric current to various electric appliances. Fig. 3 is a principal electric appliances system diagram in a two-wheeled motor vehicle having an output control unit for the ACG 1. In the same figure, an ECU (electric control unit) 3 is provided with a full wave rectifier 4 for rectifying a three-phase alternating current generated in the ACG 1 and a regulator 5 for restricting an output of the full wave rectifier 4 to a predetermined regulating voltage (regulator operating voltage: say 14.5V). The ECU 3 is further provided with a power generation controller 6 which makes control to increase the generated energy when the number of revolutions of the engine lies in a predetermined low revolution region ("power generation control region" hereinafter). The power generation controller 6 is implemented as the function of a CPU. The rotor angle sensors 29 and the ignition pulser 30 are also connected to the ECU 3 and their detected signals are inputted to the ECU 3. An ignition coil 21 is connected to the ECU 3 and a spark plug 22 is connected to a secondary side of the ignition coil 21. To the ECU 3 are also connected a throttle sensor 23, a fuel sensor 24, a seat switch 25, an idle switch 26, and a cooling water temperature sensor 27, and their detected signals are inputted to the ECU 3. Further connected to the ECU 3 are a starter relay 34, a starter switch 35, stop switches 36 and 37, a stand-by indicator 38, a fuel indicator 39, a speed sensor 40, an auto-by starter 41, and a headlight 42. A dimmer switch 43 is provided in the headlight 42. An electric current is fed to the above various portions from a battery 2 through a main fuse 44 and a main switch 45. The battery 2 is directly connected to the ECU 3 through a starter relay 34 and has a circuit through which it is connected to the ECU 3 via the main fuse 44 alone without going through the main switch 45. The power generation controller 6 has, in addition to the ordinary function of controlling the generated energy (voltage), a function of retard-energizing the stator coils of the three phases in the ACG 1 from the battery 2 to increase the generated energy ("ACG energizing control" hereinafter). The "retard-energizing" means making a retard corresponding to a predetermined electrical angle from a detection signal obtained by any of the rotor angle sensors 29 at the time of a pole change in one magnetized zone of the magnet ring 33 and energizing the stator coils. However, for preventing unstable rotation of the engine caused by a sudden change of the engine load which is induced by operation of the regulator 5 in a low revolution gC3¥JP01/U8873 region, a control is made so that an output voltage (battery voltage) of the full wave rectifier 4 is within a predetermined voltage range which is not higher than the regulating voltage. Fig. 4 illustrates a relation between the engine speed and a generated electric current detected when the ACG energizing control is conducted. In the same figure, an engine speed range of 1000 to 3500 rpm is set as a power generation control range. In such a low revolution region, a generated electric current (ACG output) of the ACG 1 obtained by the conventional control method is very small. Therefore, the generated electric current is increased by the ACG energizing control in the power generation control range. The increment is designated "retard-energizing" and is indicated with a dotted line in the figure. By making control so that the generated energy corresponds to a normal load current, it is possible to ensure a generated energy corresponding to a consumed current quantity also in the low revolution region. Fig. 5 illustrates how the battery voltage changes in a retard power generation region. In the same figure, the battery voltage Vb is controlled in an ACG control voltage range which is defined by both a maximum control voltage value VMax set below the regulating voltage (14.5V) and a minimum control voltage value VMin. More specifically, an energizing retard quantity for the stator coils is fixed (say 60° in terms of an electrical angle) and the energizing duty of the full wave rectifier 4 is increased or decreased to control the battery voltage Vb to a value falling under the ACG control voltage range. More particularly, upon arrival of the battery voltage Vb at the maximum control voltage value VMax, the energizing duty is decreased by a predetermined very small value (say 1%), while upon drop of the battery voltage Vb to the minimum control voltage value VMin, the energizing duty is increased by the same very small value as above. Fig. 1 is a block diagram showing functions of principal portions in the ACG energizing control unit. In the same figure, the full wave rectifier 4 has FETs (generally solid switching elements) 4a, 4b, 4c, 4d, 4e, and 4f which are connected to the stator coils 1U, IV, and 1W of the ACG 1. At the time of starting the engine, the FETs 4a to 4f are switched by a driver 4 6 to drive the ACG 1 as a synchronous motor, causing the crank shaft 201 to rotate, while after the start-up of the engine the outer rotor, conversely, is driven by the engine and functions as a synchronous motor, so that the generated alternating current is rectified by the FETs 4a to 4f and the resulting current is fed to the battery 2 and an electric appliance load 47. Also during power generation under operation of the engine, particularly in a low revolution of the engine, the FETs 4a to 4f are controlled by the driver 46 so that the retard energizing to the stator coils is performed in accordance with the present invention, thereby increasing the generated energy. As to the retard energizing control, it will be described later with reference to Fig. 7. An engine speed decision unit 48 detects an engine speed on the basis of, for example, a detection signal provided from the ignition pulser 30 or a frequency signal of a generated voltage and provides a retard command to the driver 46 if the detected engine speed lies in a predetermined power generation control range. In response to the retard command the driver 46 reads out a preset energizing retard quantity from a retard quantity setting unit 49 and retard-energizes the stator coils. The energizing duty is read out from the duty setting unit 51 and is fed to the driver 46. The driver 4 6 detects a magnetic pole detection signal provided from each rotor angle sensor 29, i.e., a signal which rises ON every time the sensor 29 detects a portion of the magnetized zone in the magnet ring 33 formed correspondingly to the magnetic poles of the outer rotor 60. Then, the driver 46 makes a retard corresponding to the energizing retard quantity from the time when the signal rises and outputs a PWM control signal to the FETs 4a~4f. A battery voltage decision unit 52 compares the battery voltage Vb with the maximum control voltage value VMax and the minimum control voltage value VMin both of which define the voltage control range and, on the basis of the result of the comparison, increases or decreases the energizing duty set in the duty setting unit 51 so that the battery voltage Vb falls under the above control range. Fig. 6 is a flow chart showing processings executed by the output control unit described above. In the same figure, it is judged in step Si whether the engine speed lies in the power generation control region or not. As noted earlier, the power generation control region is set, for example, in the range from 1000 to 3500 rpm. If the engine speed lies in the power generation control region, the processing flow advances to step S2, in which a check is made to see if there is set (=1) a flag FACG indicating that the engine speed lies in the power generation control region. If the answer is negative, the flow advances to step S3 to set the flag FACG (set to "1"). Once the flag FACG is set, the flow advances to step S4, in which an energizing retard value acgagl is set at a predetermined value ACGAGL. The predetermined value ACGAGL may be set to an appropriate value in advance, say, 60° in terms of an electrical angle in this embodiment. In step S5 which follows, an energizing duty acduty is set at an initial value ACDUTY. The initial value ACDUTY may also be set to an appropriate value in advance, say, 40% in this embodiment. If the processings of steps S3 to S5 are over, the flow advances to step S7. Also, if the answer in step S2 is affirmative, steps S3 to S5 are skipped and the flow advances to step S7. Further, if the engine speed does not lie in the power generation control region, the flag FACG is reset (= 0) in step S6 and thereafter the flow advances to step S7. In step S7, a check is made to see if the flag FACG is set or not. If the flag FACG is set (= 1), it is judged in step S8 whether the battery voltage Vb is not smaller than the maximum control voltage value VMax. The maximum control voltage value VMax is set to a value lower than the regulating voltage, say, 13.5V. If the answer in step S8 is negative, the flow advances to step S9, in which a check is made to see if the battery voltage Vb is not larger than the minimum control voltage value VMin, which value is set to say 13.0V. If the answer in step S9 is negative, it is judged that the battery voltage lies in the ACG energizing voltage range which is set lower than the regulating voltage of the regulator. Then, the flow advances to step S10, in which ACG energizing control is executed in accordance with the energizing retard quantity acgagl and the energizing duty acduty. If it is judged in step S8 that the battery voltage Vb is not smaller than the maximum control voltage value VMax, the flow advances to step Sll, in which the energizing duty acduty is decreased by a very small value DDUTY, which value is say 1%. If it is judged in step S9 that the battery voltage Vb is not larger than the minimum control voltage value VMin, the flow advances to step S12, in which the energizing duty acduty is increased by the very small value DDUTY. After the processings of steps Sll and S12, the flow advances to step SlO. The very small value DDUTY used in increasing the energizing duty acduty and that used in decreasing the acduty need not always be equal to each other. The very small value DDUTY may be changed in proportion to the difference between the maximum or minimum control voltage value VMax or VMin and the present value. On the other hand, if the flag FCG is not set (=0) in step S7, since the engine speed is not in the power generation control region, the flow advances to step S13 to stop the ACG energizing control. Fig. 7 illustrates a timing between electric currents (phase currents) flowing in the three phases of the stator coils in ACG energizing control and outputs of the rotor angle sensors 29. As shown in the same figure, in a normal condition wherein the retard energizing control is not performed, an electric current is fed to each of U, V, and W phases of the stator coils in response to positive-negative (NS) changes in detected outputs provided from the rotor angle sensors 29. On the other hand, in the case where the retard energizing control is performed, an electric current is fed to each of U, V, and W phases of the stator coils with a delay corresponding to a predetermined retard quantity, d (= 60° ) , from the time when there occurs a positive-negative (NS) change in the detected output provided from each rotor angle sensor 29. In Fig. 7, a retard angle T resulting from duty chopping is 180° , but it may be determined inside of 180° by the energizing duty fed from the duty setting unit 51 to the driver 46. Fig. 8 is an energizing duty table in which the engine speed, i.e., the number of revolutions of the generator is set as a parameter. An energizing duty is determined in accordance with a detected engine speed and by reference to Fig. 8. In the above embodiment there is adopted an outer rotor/inner rotor system in which permanent magnets as field flux generating magnet means are disposed in the outer rotor. However, the present invention is also applicable to a generator in which field flux generating magnet means is provided in an inner rotor or a generator which adopts electromagnets as field flux generating magnet means. Further, without using a fixed value as the energizing retard quantity acgagl there may be adopted a proportional, differential, or integral control, or a combination thereof in accordance with a conventional negative feedback control method. Industrial Applicability As will be apparent from the above description, according to the invention defined in claims 1 to 4, it is possible to increase the generated energy stably without operation of an ordinary type of a voltage regulator in a low revolution region. Consequently, when the invention is applied to a vehicular generator in which a rotor is driven by an engine, it is possible to diminish a variation of the engine load during idling for example, thereby minimize a variation of the engine revolution and stabilize the idling operation. According to the invention defined in claims 2 to 4, since the retard timing is fixed to a preset value, the generated energy can be adjusted easily with a simple configuration and it is possible to improve the adjustment accuracy. We claim: 1. An output control unit for a synchronous generator (1) having a rotor (60) provided with field flux generating magnet means (62) and a stator (50) with stator windings thereon for producing a generated output, comprising: detector means (30) for detecting the number of revolutions of said rotor (60); energizing means (46) for, when the number of revolutions of said rotor is in a low revolution region, retard-energizing said stator windings to increase a generated energy of the generator so as to control an output voltage of the generator to be a voltage control value which is set lower than a regulating voltage; and a regulator (5) for restricting an output voltage of the generator to a regulating voltage, wherein said retard-energizing is performed when the number of revolutions of said rotor (60) lies in a low revolutions region and it is performed so as to control said output voltage to a predetermined voltage control value lower than said regulating voltage. 2. An output control unit for a synchronous generator (1) as claimed in claim 1, wherein, the said energizing means comprises means for changing an energizing duty while maintaining an energizing retard quantity at a predetermined value s 3. An output control unit for a synchronous generator (1) as claimed in claim 2, wherein, said energizing means comprises means for increasing or decreasing the energizing duty so as to make the output voltage fall within a predetermined range of the voltage control value. 4. An output control unit for a synchronous generator (1) as claimed in claims 2 or 3, wherein, in said energizing means further comprises means for determining said energizing duty in accordance with a number of revolutions of the generator (1). Dated this 14th day of February, 2003 [RANJNA MEHTA DUTT] OF REMFRY & SAGAR ATTORNEY FOR THE APPLICANTS

Documents:

228-mumnp-2003-cancelled pages(4-7-2008).pdf

228-mumnp-2003-claims(granted)-(4-7-2005).doc

228-mumnp-2003-claims(granted)-(4-7-2005).pdf

228-mumnp-2003-correspondence(16-3-2006).pdf

228-mumnp-2003-correspondence(ipo)-(18-8-2004).pdf

228-mumnp-2003-drawing(4-7-2005).pdf

228-mumnp-2003-form 19(21-7-2004).pdf

228-mumnp-2003-form 1a(14-2-2003).pdf

228-mumnp-2003-form 2(granted)-(4-7-2005).doc

228-mumnp-2003-form 2(granted)-(4-7-2005).pdf

228-mumnp-2003-form 3(14-2-2003).pdf

228-mumnp-2003-form 5(14-2-2003).pdf

228-mumnp-2003-form-pct-ipea-409(4-7-2008).pdf

228-mumnp-2003-pettition under rule 137(4-7-2005).pdf

228-mumnp-2003-pettition under rule 138(4-7-2005).pdf

228-mumnp-2003-power of authority(10-2-2003).pdf

228-mumnp-2003-power of authority(4-7-2005).pdf

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