JPH10201297A - Power-generation device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To optimize a drive torque of its own by, in a power generation device for an internal combustion engine, generating a rotary field at a multi- phase of a rotor. SOLUTION: When an electric load increases to 40A while an electric power of 30A is generated at a relative speed N10, a speed N2 of a rotary field generated electrically at a multi-phase coil of a rotor is increased, for a relative speed to be increased from N10 to N20. As a result, with a drive torque kept constant, the amount of power generation is increased from 30A to 40A. Then, the amount of power generation kept constant, a rotary field speed N2 is so gradually changed that a relative speed N agrees with a high efficient rotation speed Nx by being accompanied with fluctuation of drive torque. The control of rotary field speed N2, in short, that of relative speed N is desired to be so gradually performed at such level of speed as no drive torque fluctuation is experienced with a driver, nor represented as an abrupt shock at an alternator belt.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine (hereinafter referred to as "internal combustion engine").
The present invention relates to a power generator for an internal combustion engine that converts rotational energy into electric energy (in some cases, referred to as an engine). In particular, it can optimize its own driving torque by generating a rotating magnetic field in a multi-phase winding of a rotor. The present invention relates to a power generator for an internal combustion engine as described above.

[0002]

2. Description of the Related Art In a power generator for a vehicle or a marine vessel, a rotating shaft is connected to an engine crankshaft via an alternator belt, and an alternator (ACG) converts alternating current generated by the alternator according to the engine speed into direct current. It is composed of a rectifier for converting to electric power and a regulator for controlling the voltage of DC power according to the battery voltage.

FIG. 9 is a schematic diagram showing a configuration of a conventional alternator 50. A DC field coil 53 is wound around a rotor (rotor) 52 integrated with a rotating shaft, and a stator 54 (fixed). ) Is wound with a three-phase coil 55. Here, when the rotor 52 is rotated in an excited state in which a DC current is supplied from the battery to the DC field coil 53 to form an alternating magnetic field arrangement, the three-phase coil 55 of the stator 54 has a rotation speed corresponding to the rotation speed of the rotor 52. AC power of the frequency is generated. That is, the conventional alternator is a generator using a synchronous motor. The rotor 52 may be provided with a permanent magnet instead of the DC field coil 53.

[0004]

In the above-mentioned internal combustion engine for a vehicle or the like, when an electric load having a large power consumption such as a headlight or an air conditioner is turned on / off,
In response to this, the excitation intensity of the DC field coil 53 is also controlled to increase or decrease the amount of power generation. As a result, the torque required for the engine to drive the alternator (hereinafter simply referred to as drive torque) fluctuates, and the engine speed changes. In particular, when a large electric load changes from an off state to an on state and the driving torque increases sharply, the engine speed decreases accordingly.If the engine is idling, it may cause an engine stall or even during running. In such a case, there arises a problem that the drivability deteriorates due to a kind of braking state.

In order to solve such a problem, for example, Japanese Unexamined Patent Publication No. 1-277650 discloses a method of determining whether or not an electric load is applied. A control device for increasing the set value of the number has been proposed. Further, Japanese Patent Laid-Open No. 5-1804 / 1993
Japanese Patent Application Laid-Open No. 7-212,199 proposes a control device that controls a duty ratio of a field current supplied to a field coil of a stator in accordance with an increase or a decrease in an electric load. However, in any of the above-described conventional techniques, since the drive torque of the alternator fluctuates in accordance with the increase or decrease in the electric load, a large load is applied to the alternator belt, or stability is still lacking because quick control cannot be performed. There was a problem.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and to employ an induction machine as an alternator, which causes a change in the drive torque of the alternator, such as a change in electric load or engine speed. Another object of the present invention is to provide a power generator for an internal combustion engine, the drive torque of which can be arbitrarily controlled.

[0007]

Means for Solving the Problems In order to achieve the above object, the present invention is characterized in that the following means are taken. (1) An induction machine including a rotor and a stator having a multi-phase winding, the rotor being rotated by the rotation of the internal combustion engine being transmitted, and a rotating magnetic field generating means for generating a rotating magnetic field in the multi-phase winding of the rotor. The rotating magnetic field generating means controls the speed of the rotating magnetic field so that the driving torque of the induction machine falls within a predetermined range. (2) The rotating magnetic field generating means, when an event to change the driving torque of the induction machine occurs, the rotating magnetic field speed such that the driving torque is maintained at any of a predetermined value or more, a predetermined value or less, and a predetermined value. Was controlled. (3) The predetermined value is made to be a function of the temperature of the induction machine. (4) The event that causes the drive torque to fluctuate is an increase or decrease in the rotor rotational speed, and the rotating magnetic field generating means adjusts the rotational magnetic field speed so that the drive torque after the rotor rotational speed increases or decreases is kept at or below a predetermined value. Increase or decrease. (5) The rotating magnetic field generating means increases the rotating magnetic field speed when the remaining capacity of the battery charged by the induction machine is insufficient, and decreases the rotating magnetic field speed when the remaining battery capacity is sufficient. (6) The event that causes the drive torque to fluctuate is an increase or decrease in an electric load.The rotating magnetic field generating unit controls the rotating magnetic field speed so as to cover the increased or decreased electrical load without accompanying a drive torque change. The rotating magnetic field control accompanying the drive torque fluctuation is executed gradually so that the electric load after the increase or decrease can cover the relative rotational speed of the rotating magnetic field with respect to the stator even at the predetermined rotational speed. (7) The predetermined rotation speed is the rotation speed at which the power generation efficiency of the induction machine is the highest. (8) The rotating magnetic field generating means controls the rotating magnetic field speed according to the vehicle state so that the driving torque of the induction machine is increased or decreased from the present.

According to the above configuration (1), even if a factor such as an increase or decrease of an electric load that fluctuates the driving torque when the induction machine is used as a generator occurs, the driving torque is reduced to a predetermined range. Can be kept within.

According to the above configuration (2), even if an event occurs that fluctuates the drive torque of the induction machine, the drive torque of the induction machine can be controlled to a predetermined value.

According to the above configuration (3), the driving torque of the induction machine can be controlled to a predetermined value regardless of the temperature of the induction machine.

According to the above configuration (4), the load on the alternator belt is reduced.

According to the above configuration (5), the driving torque can be controlled according to the remaining capacity of the battery.

According to the above configuration (6), even if the electric load increases or decreases, the ideal control of the amount of generated electric power can be performed without any fluctuation in the driving torque.

According to the above configuration (7), efficient power generation becomes possible.

According to the above configuration (8), the driving torque can be arbitrarily controlled according to the vehicle state. Therefore, when an acceleration state is detected, the relative speed is increased to reduce the driving torque, and the engine torque is reduced. When a braking state is detected, the driving performance is increased by reducing the relative speed, so that the acceleration performance and the engine braking performance are improved.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the basic concept of the present invention will be described. The substantial rotation speed of the induction machine can be represented by the relative speed N of the rotating magnetic field generated by the rotor with respect to the stator coil, and the field winding (polyphase winding) of the rotor generates a DC magnetic field instead of a rotating magnetic field. The relative speed N is equal to the mechanical rotation speed of the rotor. Here, considering the case where a rotating magnetic field is generated in the multi-phase winding of the rotor, if the mechanical rotation speed of the rotor is N1 and the speed of the rotating magnetic field generated in the multi-phase winding of the rotor is N2, The relative speed N is represented by the following equation. N = N1 + N2 (1) That is, the relative speed N of the rotating magnetic field generated by the rotor of the induction machine with respect to the stator coil is determined by the mechanical rotating direction of the rotor and the rotating direction of the rotating magnetic field generated by the multi-phase winding of the rotor. If they match, the rotational speed becomes faster than the mechanical rotational speed N1 of the rotor, and if the rotational direction is reversed, it becomes slower than the rotational speed N1 of the rotor. Therefore, if the induction machine is adopted as an alternator for a vehicle, no matter how the mechanical rotation speed N1 of the rotor changes in synchronization with the engine speed, a change is generated in the multiphase winding of the rotor in response to the change. The relative speed N can be arbitrarily controlled by appropriately controlling the rotating magnetic field speed N2.

On the other hand, as shown in FIG. 10, since the drive torque T of the alternator can be expressed as a function of the relative speed N, the relative speed N of the rotating magnetic field can be arbitrarily controlled as described above. If possible, the drive torque T of the alternator can be arbitrarily controlled regardless of the mechanical rotation speed N1 of the rotor.

Thus, in the present invention, the drive torque T of the induction machine is a function of the relative speed N of the rotating magnetic field with respect to the stator, and the relative speed N is the rotating magnetic field speed N2 generated in the multi-phase winding of the rotor. The control torque can be arbitrarily controlled irrespective of the mechanical rotation speed N1 of the rotor, and the drive torque of the induction machine can be arbitrarily controlled according to the state of the vehicle.

Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a main part of a vehicular power generating device according to an embodiment of the present invention, and FIG. 2 is a diagram showing a configuration of an alternator 1 constituting the power generating device of the present invention. (A) is a sectional view on a plane perpendicular to the rotation axis, and (b) is a sectional view on a plane parallel to the rotation axis.
The alternator 1 of the present invention includes a three-phase winding, that is, a three-phase field coil 1 for each of the rotor 1R and the stator 1S.
This is a so-called induction machine in which 1, 12 are formed.

In FIG. 2, the rotating shaft 1 of the alternator 1
3, a rotor 1R having a three-phase field coil 11 is coaxially fixed, and a stator 1S having a three-phase field coil 12 is arranged around the rotor 1R. The rotating shaft 13 is rotatably supported by the housing 17 via a front bearing 15a and a rear bearing 15b. A pulley 14 is fixed to one end of the rotating shaft 13, and each field coil 11 of the rotor 1 </ b> R is fixed to the other end.
(11a-11c) Brush 19a for supplying excitation current to
To 19c are formed in contact with slip rings 18a to 18c.

The alternator 1 at the other end of the rotating shaft 13 has a rotor exciting device 2 (described later) and an ACG / ECU.
3, the switching control device 5 and the short-circuit device 8 are arranged side by side in the circumferential direction along the inside of the housing 17 on the same plane orthogonal to the rotating shaft 13. This facilitates the routing of the wiring between the devices, enables effective use of the dead space, and suppresses the alternator from increasing in size.

In FIG. 1, when the ACG-ECU 3 detects an engine speed Ne, an electric load, and the like by communicating with the engine ECU 4, the speed N2 of the rotating magnetic field generated by the rotor 1R, the rotating magnetic field voltage, or the rotating magnetic field. The magnetic field phase and the like are determined and notified to the electric rotating magnetic field control unit 2a of the rotor excitation device 2. The electric rotating magnetic field control unit 2a
-Each field coil 11a, 11b, 11c of the rotor 1R based on the rotating magnetic field speed N2 etc. notified from the ECU 3.
To control the phase, amplitude, and frequency of the AC power supplied to the motor to electrically generate a rotating magnetic field having a rotating speed of N2.

The switching control device 5 communicates with the ACG-ECU 3 to detect the operating state of the alternator 1, and at the timing when it functions as a generator, the output terminal of the alternator 1 is connected to the contact of the output control device 7, and At the function timing, each contact of the switching circuit 6 is controlled so as to be connected to the contact of the short circuit device 8. At the timing when the alternator 1 is caused to function as a generator, a part of the output power of the alternator 1 is transferred to the electric rotating magnetic field control unit 2a.
May be supplied to the alternator 1 for self-excitation.

The output control device 7 includes a rectifier circuit 7a and a regulator 7b, and converts AC power output from the alternator 1 into DC power according to the voltage of the battery 9. The short-circuit device 8 is connected to each field coil 12 of the alternator 1.
The output terminals of a, 12b, and 12c are short-circuited with or without a variable resistor. The DC excitation control unit 2b is selectively energized with the electric rotating magnetic field control unit 2a and supplies DC power to the field coils 11a and 11b of the rotor 1R to generate a magnetic field in the rotor 1R.

In such a configuration, ACG / ECU
3 is the engine speed Ne detected by the engine ECU 4
When the operating parameters such as the load and the electric load are notified, the alternator 1 is driven based on the engine speed Ne and the pulley ratio.
The mechanical rotation speed N1 of the rotor 1R is calculated. The ACG ECU 3 further controls the relative speed N of the rotating magnetic field generated by the rotor 1R with respect to the stator 1S so that the actual driving torque of the alternator 1 falls within the target driving torque range instructed by the engine ECU 4. The speed N2 of the rotating magnetic field generated electrically in the three-phase winding of 1R is calculated, and this is notified to the electric rotating magnetic field control unit 2a.

The electric rotating magnetic field control unit 2a includes a rotor 1R
The excitation timing of each phase of the three-phase coil 11 is controlled to electrically generate a rotating magnetic field at a speed N2. The AC power output from each of the field coils 11a, 11b, 11c of the rotor 1R is converted into DC power by the output control device 7, a part of which is supplied to the current electric load, and the rest is charged into the battery 9. In addition, since the control method of the induction machine itself is known, the description thereof is omitted.

Next, a specific example of drive torque control according to the present invention will be described with reference to FIG. FIG. 3A is a diagram illustrating an example of a method for controlling the driving torque in the power generator having the above-described configuration. In the present embodiment, the driving torque of the alternator 1 is limited to an upper limit regardless of the mechanical rotation speed of the rotor 1R. The torque is limited to less than Tmax. Such torque control is performed at a lower speed lower limit Na or a lower speed lower limit Nb determined by the upper limit torque Tmax.
As described above, this is achieved by controlling the speed N2 of the rotating magnetic field generated electrically in the three-phase winding of the rotor 1R in accordance with the mechanical rotation speed N1 of the rotor 1R so that the relative speed N is maintained. You.

FIG. 8 is a flowchart showing the operation of the above embodiment. In step S1, the mechanical rotation speed of the alternator 1, that is, the rotor rotation speed N1 is measured. This rotation speed N1 is, for example, the engine rotation speed Ne.
And the pulley ratio. In step S2, the current drive torque T of the alternator is measured. The driving torque T may be measured by using a torque meter, but can also be measured by measuring the output current and the exciting current of the alternator 1.

In step S3, it is determined whether or not the detected drive torque T exceeds the upper limit torque Tmax.
If it is determined that it has exceeded, in step S4, the remaining battery charge is detected based on the battery voltage. Here, since the power generation amount M of the alternator increases as the relative speed N increases, in the present embodiment, if it is determined in step S4 that the remaining battery capacity is insufficient (for example, the battery voltage is 12 V or less), In step S5a, a rotating magnetic field speed for increasing the relative speed N and reducing the driving torque T, that is, a rotating magnetic field speed + N2 for making the relative speed N equal to or higher than the high-speed lower limit value Nb is calculated. On the other hand, the remaining battery capacity is sufficient (for example, when the battery voltage is 12.5
V or more), in step S5b, the rotating magnetic field speed for reducing the relative speed N to reduce the driving torque T,
That is, the rotating magnetic field speed -N2 for making the relative speed N equal to or lower than the lower speed upper limit Na is calculated. Step S6
Then, a rotating magnetic field of speed N2 is induced in the multi-phase winding of the rotor.

FIG. 3B shows an example of another method of controlling the drive torque of the alternator 1. In the present embodiment, the drive torque of the alternator 1 is controlled regardless of the mechanical rotation speed of the rotor. The torque is kept at or above the lower limit torque Tmin. Such a torque control also requires the relative speed N
Is controlled by controlling the rotating magnetic field speed N2 according to the mechanical rotation speed N1 of the rotor 1R so that the rotation speed does not fall below the lower limit value N3.

FIG. 3C is a diagram showing an example of still another control method of the driving torque. In this embodiment, FIG.
The drive torque of the alternator is maintained at a constant torque Tc regardless of the mechanical rotation speed of the rotor.
Such a torque control also requires the mechanical rotation speed N of the rotor 1R so that the relative speed N always matches the target speed N4.
This is achieved by controlling the rotating magnetic field speed N2 in accordance with (1).

According to the present embodiment, the drive torque T of the alternator can be kept within a desired predetermined value or within a predetermined range regardless of the rotation speed N1 of the rotor 1R.
It is possible to prevent an excessive increase or decrease of the load on the alternator belt, or a large change in load,
Variations in engine speed can also be prevented.

By the way, in the alternator, when the temperature decreases, the electric resistance of the multi-phase winding decreases and a large amount of exciting current flows. Therefore, as shown in FIG. 4, the driving torque at the same relative speed is lower than that at the time of high temperature. Time is higher. Therefore, for example, the drive torque of the alternator is changed to the upper limit torque Tma.
When the relative speed N is to be limited to x or less, the lower limit and the lower limit of the relative speed N are changed from NaH and NbH at the time of high temperature to NaL and NbL at the time of low temperature. Therefore, if the drive torque T of the alternator is controlled to be within the target value or the target range based on the relative speed N in the manner described above, the relative speed N and the drive torque T are determined by using the temperature of the alternator 1 as a parameter. It is desirable to define the relationship in advance.

In each of the above control methods, the drive torque of the alternator has been described as being controlled within an absolute range or an arbitrary value. However, the drive torque may be set higher or lower than the current drive torque. Alternatively, it may be relatively controlled in relation to the current drive torque.For example, if the rotational magnetic field speed is controlled so that the drive torque of the induction machine is increased or decreased according to the vehicle state, good.

That is, as in the second embodiment of the present invention shown in FIG. 5, for example, the operating point A where the electric load is 40 A
When the acceleration state of the vehicle is detected based on the accelerator opening, the engine speed, and the like in the state described above, the rotating magnetic field speed N2
Is increased by ΔN21 to increase the relative speed N, whereby the operating point is shifted to C to lower the driving torque. Further, when the engine braking state of the vehicle is detected, the relative magnetic field speed N2 is reduced by ΔN22 to reduce the relative speed N, thereby shifting the operating point to B and increasing the driving torque, thereby improving the acceleration performance and engine performance. Brake performance is improved.

Next, a third embodiment of the present invention will be described. In the above-described first and second embodiments, the electric load of the alternator 1 is not taken into consideration. However, in actual use, the electric load greatly fluctuates due to ON / OFF of an air conditioner, a headlamp, and the like. The relationship between the relative speed N and the driving torque T also greatly changes. FIG. 6 is a diagram showing the relationship between the relative speed N of the alternator 1 and the driving torque T using the electric load as a parameter. Even if the relative speed N is the same, the driving torque T increases as the electric load increases. I understand.

Here, if the electric load increases to 40 A while generating 30 A of electric power at the relative speed N10, the driving torque normally increases from T1 to T2. For this reason, a shock corresponding to the torque fluctuation is generated in the vehicle, and an increase in drive torque may cause a temporary decrease in engine speed. Therefore, in the present embodiment, when the drive torque is likely to fluctuate due to an increase or decrease in the electric load, the increase or decrease in the electric load is compensated for by an increase or decrease in the relative speed N, thereby preventing the torque fluctuation. That is, in this embodiment, when the electric load is increased to 40 A while the electric power of 30 A is generated at the relative speed N10 as described above, the rotating magnetic field speed N2 is increased to increase the relative speed from N10 to N20. As a result, it is possible to increase the power generation amount from 30A to 40A while keeping the driving torque constant.

Further, as shown in FIG. 7, the relationship between the relative speed N of the alternator and the power generation efficiency η shows the maximum efficiency ηmax at a certain point Nx with the relative speed N, and as the distance from the maximum efficiency rotation speed Nx increases. The power generation efficiency η decreases.
Therefore, it is desirable to maintain the relative speed N at the rotational speed at which the maximum efficiency ηmax is obtained.

Therefore, in the present embodiment, when an event such as an increase or decrease in the electric load that fluctuates the drive torque of the alternator occurs, in order to compensate for the fluctuation without first fluctuating the drive torque as described above, The relative speed N is controlled by changing the speed N2 of the rotating magnetic field electrically generated in the multi-phase winding. After that, while the power generation amount is kept constant, the relative speed N becomes maximum with the fluctuation of the driving torque. The rotating magnetic field speed N2 is gradually changed so as to match the efficient rotating speed Nx. At this time, the control of the rotating magnetic field speed N2, that is, the control of the relative speed N, is preferably performed gradually at such a speed that the driving torque fluctuation is not felt by the driver or appears as a sudden shock on the alternator belt.

According to the present embodiment, even if an event such as a change in the drive torque of the alternator, that is, an increase or decrease in the engine speed or the electric load occurs, the change in the drive torque of the alternator is not suddenly changed. Be able to deal with it.

Although the present embodiment has been described by taking as an example an induction machine constituted by a rotor and a stator having three-phase windings as multi-phase windings, the present invention is not limited to this, and the present invention is not limited to this. The same applies to the case where other multi-phase windings such as five-phase windings are employed.

[0042]

As described above, according to the present invention, the following effects can be achieved. (1) According to the first aspect of the present invention, the drive torque of the alternator can be kept within a predetermined range regardless of the mechanical rotation speed of the rotor. Fluctuations can be prevented. (2) According to the second aspect of the present invention, even if an event that varies the driving torque of the induction machine occurs, the driving torque of the induction machine can be kept within a predetermined range. More specifically, if the drive torque is maintained at or above a predetermined value,
Fluctuation of the load on the alternator belt is prevented, and vibration and noise can be reduced. If the drive torque is kept below the predetermined value, an excessive load on the alternator belt is prevented. Further, if the driving torque is maintained at a desired predetermined value, both the load fluctuation and the excessive load of the alternator belt can be prevented. (3) According to the third aspect of the invention, the driving torque of the induction machine can be controlled to the predetermined value regardless of the temperature of the induction machine. (4) According to the invention of claim 4, the load on the alternator belt is reduced. (5) According to the invention of claim 5, it is possible to perform drive torque control according to the remaining capacity of the battery. (6) According to the invention of claim 6, even if the electric load increases or decreases,
At first, power generation control without driving torque fluctuation is performed,
After that, since the power generation control accompanying the drive torque fluctuation is performed gradually, even if the electric load increases or decreases, the ideal power generation control can be performed without the drive torque fluctuation being felt. (7) According to the invention of claim 7, efficient power generation becomes possible. (8) According to the invention of claim 8, since the drive torque can be arbitrarily controlled according to the vehicle state, when the acceleration state is detected, the relative speed is increased to reduce the drive torque, and the engine brake is reduced. When the state is detected, if the driving torque is increased by reducing the relative speed, the acceleration performance and the engine braking performance are improved.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of a vehicular power generating device of the present invention.

FIG. 2 is a diagram showing a configuration of an alternator of the present invention.

FIG. 3 is a diagram for explaining a control method according to the first embodiment of the present invention.

FIG. 4 is a diagram showing a relationship between a relative speed N and a driving torque T using an alternator temperature as a parameter.

FIG. 5 is a diagram illustrating a control method according to a second embodiment of the present invention.

FIG. 6 is a diagram illustrating a control method according to a third embodiment of the present invention.

FIG. 7 is a diagram showing a relationship between a relative speed N of a rotating magnetic field and an efficiency η.

FIG. 8 is a flowchart illustrating a control method according to the first embodiment.

FIG. 9 is a diagram showing a configuration of a main part of an alternator according to the related art.

FIG. 10 is a diagram showing a relationship between a relative speed N and a driving torque T.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Alternator, 1R ... Rotor, 1S ... Stator, 2
... Rotator excitation device, 3 ... ACG / ECU, 4 ... Engine ECU, 5 ... Switching control device, 7 ... Output control device, 8 ... Short-circuit device, 9 ... Battery, 11, 12 ... 3-phase field coil,
Reference numeral 13: rotating shaft, 14: pulley, 15a: front bearing, 15b: rear bearing, 17: housing,
18a-18c ... slip ring, 19a-19c ... brush

Continued on the front page (72) Inventor Tadashi Fujiwara 1-4-1, Chuo, Wako-shi, Saitama Pref. Inside of Honda R & D Co., Ltd. (72) Inventor Shinsuke Nagano 1-4-1, Chuo, Wako-shi, Saitama Co., Ltd. Inside Honda Technical Research Institute (72) Inventor Takuya Fujita 1-4-1 Chuo, Wako-shi, Saitama

Claims (8)

[Claims] An induction machine including a rotor having a multi-phase winding and a stator, wherein the rotor rotates by transmitting the rotational motion of an internal combustion engine, and a rotating magnetic field generating means for generating a rotating magnetic field in the multi-phase winding of the rotor Wherein the rotating magnetic field generating means controls the speed of the rotating magnetic field so that the driving torque of the induction machine falls within a predetermined range. 2. The rotating magnetic field generating means according to claim 1, wherein, when an event that fluctuates the driving torque of the induction machine occurs, the rotating magnetic field generating means rotates such that the driving torque is maintained at any of a predetermined value or more, a predetermined value or less, and a predetermined value. The power generator for an internal combustion engine according to claim 1, wherein the magnetic field speed is controlled. 3. The power generator according to claim 2, wherein the predetermined value is a function of the temperature of the induction machine. 4. An event that causes the drive torque to fluctuate is an increase or a decrease in the rotor rotational speed. The rotating magnetic field generating means controls the rotational magnetic field so that the drive torque after the increase or decrease in the rotor rotational speed is maintained at a predetermined value or less. The power generator for an internal combustion engine according to claim 2 or 3, wherein the speed is increased or decreased. 5. The rotating magnetic field generating means increases the rotating magnetic field speed when the remaining capacity of the battery charged by the induction machine is insufficient, and decreases the rotating magnetic field speed when the remaining battery capacity is sufficient. The power generator for an internal combustion engine according to claim 4, characterized in that: 6. The event that causes the drive torque to fluctuate is an increase or decrease in an electric load, and the rotating magnetic field generating unit controls the rotating magnetic field speed so as to cover the increased or decreased electrical load without accompanying a drive torque change. 3. The method according to claim 2, wherein the electric load after the increase / decrease is controlled gradually by a rotating magnetic field control accompanied by a drive torque fluctuation so that the relative speed of the rotating magnetic field with respect to the stator can be covered even at a predetermined rotational speed. Power generator for internal combustion engines. 7. The power generator for an internal combustion engine according to claim 6, wherein the predetermined rotation speed is a rotation speed in a region where the power generation efficiency of the induction machine is highest. 8. The rotating magnetic field generating means according to claim 1, wherein said rotating magnetic field generating means controls the rotating magnetic field speed according to a vehicle state so that the driving torque of the induction machine increases or decreases as compared with the present. Power generator for internal combustion engines.