JP2010051145A - Rotary electric machine for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotary electric machine for a vehicle, capable of enhancing power generation characteristics by preventing output reduction all over the rotational range. <P>SOLUTION: The rotary electric machine 1 comprises a field winding 3 magnetizing the field poles of a rotor, an armature inducing AC voltage through the rotating field generated with the field poles, a rectifier converting the AC voltage induced with the armature into DC voltage through synchronous rectification, and a control unit 7 switching the operation state of the synchronous rectification in a predetermined rotation speed or a predetermined rotation speed range. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a vehicular rotating electrical machine mounted on a passenger car, a truck, or the like.

In some vehicle categories, vehicles equipped with an idle stop function that stops the engine during a temporary stop such as waiting for a signal have become widespread in order to respond to recent fuel efficiency regulations against environmental problems and tightening regulations for reducing CO ₂ emissions. Have begun to do.

  As one of the means for an automobile to perform idle stop, a rotating electric machine that adds a motor function to an AC generator for a vehicle and combines a starting motor for starting an engine after a temporary stop and a generating function for generating power is combined. Necessary. In addition to the starting torque characteristics for restarting the engine, the functions required for the rotating electrical machine that performs idle stop include regenerative power generation characteristics during driving due to the increase in vehicle load accompanying the recent electronics conversion of automobiles. High efficiency and high output have been demanded.

  There is a synchronous rectification method using a three-phase inverter as means for realizing high efficiency and high output of regenerative power generation characteristics. When synchronous rectification is performed in a generator motor, a switching element is used for a period during which a current flows through a diode by a three-phase inverter bridge circuit connected between an output terminal and a GND terminal of a vehicular rotating electrical machine, that is, a phase in which a current flows. By turning on, rectification loss can be reduced by the effect of a switching element having an on-resistance lower than that of a diode (see, for example, Patent Documents 1 and 2).

And V _F -I _F characteristics of the diodes, the balance with V _DS -I _D characteristic of the switching elements (MOS-FET), in a low output and low-speed region than the forward voltage drop V _F of the diode, MOS- Since the FET drain-source voltage _VDS is lower, the rectification loss is reduced, which leads to improvement in regenerative power generation efficiency. In particular, the effect is great in a three-phase full-bridge inverter using a MOS-FET.
Japanese Patent Laying-Open No. 2004-7964 (pages 10-14, FIGS. 1-8) JP 2004-147461 A (page 7-6, FIGS. 1-4)

By the way, when the MOS-FET is used instead of the diode as disclosed in Patent Documents 1 and 2, the generated current increases as the number of revolutions of the generator motor increases, resulting in a high output / high rotation range. Under these conditions, the drain-source voltage V _DS of the MOS-FET increases linearly with the rotational speed, and therefore when a current flowing exceeding the forward voltage drop V _F of the diode flows, A reverse phenomenon occurs in which the rectification loss at the time of synchronous rectification by the MOS-FET becomes larger than the rectification loss. For this reason, when synchronous rectification is performed, there is a problem in that the output is lower in the high output / high rotation region than during diode rectification. In the above description, the vehicular rotating electrical machine as a generator motor has been described. However, there is a similar problem when the rectification of a vehicular AC generator that performs only power generation is performed using a MOS-FET.

  The present invention has been created in view of the above points, and an object of the present invention is to provide a rotating electrical machine for a vehicle that can prevent a decrease in output in all rotation regions and improve power generation characteristics. It is in.

  In order to solve the above-described problems, a rotating electrical machine for a vehicle according to the present invention includes a field winding that magnetizes a field pole of a rotor, an armature that induces an AC voltage by a rotating magnetic field generated by the field pole, A rectifier that performs rectification and converts an AC voltage induced in the armature into a direct current, and a control device that switches an operation state of synchronous rectification at a predetermined rotation speed or a predetermined rotation range are provided. In particular, the rectifier described above is composed of a plurality of switching elements having parasitic diodes, and when the operation state of synchronous rectification is switched at a predetermined rotation speed, the predetermined rotation speed performs a rectification operation using the parasitic diode. The output characteristic curve in this case and the output characteristic curve in the case where the rectifying operation is performed using the switching element excluding the parasitic diode are set to the number of rotations. As a result, the rectification operation by the parasitic diode and the synchronous rectification operation by the switch element can be properly used, so that it is possible to prevent a decrease in output in all the rotation regions and improve the power generation characteristics.

  Further, when the operation state of the synchronous rectification described above is switched in a predetermined rotation range, the predetermined rotation range is rectified by using an output characteristic curve when performing a rectification operation using a parasitic diode and a switching element excluding the parasitic diode. It is desirable that the hysteresis be in a range where the rotation speed overlaps with the output characteristic curve when the operation is performed. This prevents the rectifying operation from becoming unstable by preventing frequent switching of the synchronous rectifying operation state when the rotational speed of the rotating electrical machine for the vehicle increases or decreases near the rotational speed for switching the operation state of the synchronous rectification. can do.

  In addition, the control device described above preferably causes the rectifier to perform synchronous rectification in a rotation region from a rotation speed at which power generation is started to a predetermined rotation speed when switching the operation state of synchronous rectification at a predetermined rotation speed. Further, it is desirable that the control device described above causes the rectifier to perform full-wave rectification by a parasitic diode included in the switch element in a rotation range from a predetermined rotation speed to a maximum rotation speed. This makes it possible to perform a rectifying operation using a switching element or a parasitic diode with a small loss in accordance with the number of rotations, thereby preventing a decrease in output in all rotation regions and improving power generation characteristics. In particular, when regenerative power generation is performed by a vehicular rotating electrical machine, the efficiency of regenerative power generation in a high rotation region can be increased.

  Further, it is desirable that the predetermined rotation speed or the predetermined rotation range for switching the operation state of the synchronous rectification described above is set in consideration of variation in output characteristics due to temperature. As a result, even when the temperature changes, a rectification operation with little loss is always possible, and even when the output characteristics fluctuate due to a temperature change, the rectification operation with the least loss can always be performed.

  Hereinafter, a generator motor according to an embodiment to which a vehicular rotating electrical machine of the present invention is applied will be described with reference to the drawings. Drawing 1 is a figure showing the composition of the generator motor of one embodiment. As shown in FIG. 1, the generator motor 1 of this embodiment includes an armature winding 2, a field winding 3, a three-phase inverter 4, and a control device 7.

  The armature winding 2 is a multiphase winding (for example, a three-phase winding), and is wound around an armature core to constitute an armature. When the generator motor 1 performs a power generation operation, an AC output induced in the armature winding 2 is supplied to the three-phase inverter 4. On the other hand, when the generator motor 1 performs an electric operation, an AC voltage is applied from the three-phase inverter 4 to the armature winding 2, and a rotating magnetic field is generated by the armature winding 2.

  The field winding 3 generates an interlinkage magnetic flux necessary for inducing a voltage in the armature winding 2 during a power generation operation or generating a rotational force by a rotating magnetic field of the armature winding 2 during an electric operation. The field winding 3 is wound around a field pole (not shown) to form a rotor, and the field pole is magnetized by passing a field current through the field winding.

  The three-phase inverter 4 is a three-phase bridge circuit having six MOS-FETs 5a to 5f as switching elements. Parasitic diodes are formed in the six MOS-FETs 5a to 5f, and forward current flows through these parasitic diodes from the negative terminal to the positive terminal of the three-phase inverter 4.

  The three-phase inverter 4 operates as a three-phase full-wave rectifier that performs a rectifying operation that performs synchronous rectification and converts an AC voltage induced in the armature winding 2 into a direct current during a power generation operation. This rectification operation is performed by appropriately turning on and off the MOS-FETs 5a to 5f in the low rotation region where the rotation speed is lower than the predetermined rotation speed, and is performed by a parasitic diode in the high rotation area where the rotation speed is higher than the predetermined rotation speed. Details of the switching of the rectification operation at the predetermined rotation speed will be described later.

  In addition, the three-phase inverter 4 controls the direct current applied from the battery 10 by performing on / off control of the six MOS-FETs 5 a to 5 f at a timing shifted by 120 degrees for each phase of the armature winding 2 during electric operation. It operates as an inverter circuit that converts voltage into three-phase AC voltage.

  The control device 7 performs control for causing the generator motor 1 to perform power generation operation or electric operation, and includes a reference voltage adjustment circuit 8 and an inverter control circuit 9. The reference voltage adjustment circuit 8 controls the output voltage of the generator motor 1 by adjusting the field current supplied to the field winding 3 during the power generation operation.

  The inverter control circuit 9 generates a synchronous rectification control signal that causes the three-phase inverter 4 to perform synchronous rectification by performing on / off control of the six MOS-FETs 5 a to 5 f included in the three-phase inverter 4 during the power generation operation. Further, during the power generation operation, the six MOS-FETs 5 a to 5 f included in the three-phase inverter 4 are on / off controlled, and a control signal for generating a three-phase alternating current is generated by the three-phase inverter 4.

  The generator motor 1 shown in FIG. 1 is provided with a set of armature windings 2 and a three-phase inverter 4. However, like the generator motor 1A shown in FIG. The case where the phase inverter 4 is provided may be sufficient.

  The generator motor 1 according to the present embodiment has such a configuration. Next, details of a case where the rectification operation is switched at a predetermined rotation speed during the power generation operation will be described.

  FIG. 3 is a diagram showing a specific configuration of the inverter control circuit 9. FIG. 3 shows a configuration corresponding to one phase (W phase) of the armature winding 2, and actually the same configuration is provided corresponding to each phase winding. FIG. 3 shows a partial configuration focusing on switching of a rectifying operation during a power generation operation, and a configuration for performing an electric operation is omitted.

  As shown in FIG. 3, the inverter control circuit 9 includes a synchronous rectification control signal generation circuit 90 and a frequency-voltage conversion control circuit 92. The synchronous rectification control signal generation circuit 90 generates a synchronous rectification control signal necessary for on / off control of the two MOS-FETs 5c and 5f corresponding to the W-phase winding based on the W-phase voltage of the armature winding 2 To do. Specifically, the synchronous rectification control signal generation circuit 90 performs synchronization to turn on the MOS-FET 5c constituting the high-side rectifier when the W-phase voltage becomes higher than the positive reference voltage slightly higher than 0V. A rectification control signal is generated and input to the gate of the MOS-FET 5c. Further, the synchronous rectification control signal generation circuit 90 outputs a synchronous rectification control signal for turning on the MOS-FET 5f constituting the low-side rectification unit when the W-phase voltage is lower than the negative reference voltage slightly lower than 0V. It is generated and input to the gate of the MOS-FET 5f.

  The frequency-voltage conversion control circuit 92 is for generating a synchronous rectification stop signal when the rotational speed is equal to or higher than a predetermined rotational speed. The frequency-voltage converter 11, voltage comparator CP, resistors R1, R2, R3 , R4, and R5. The frequency-voltage converter 11 converts the frequency of the W-phase voltage into a voltage, and outputs a voltage proportional to the frequency of the phase voltage. This output voltage is applied to the negative input terminal of the voltage comparator CP via the resistor R2. A resistor R3 is connected between the negative input terminal and the output terminal of the voltage comparator CP. Therefore, when the output voltage of the voltage comparator CP is at a low level, a voltage obtained by dividing the low level voltage and the output voltage of the frequency-voltage converter 11 by the resistors R2 and R3 is applied to the negative input terminal. When the output voltage of the comparator CP is high level, a voltage obtained by dividing the high level voltage and the output voltage of the frequency-voltage converter 11 by the resistors R2 and R3 is applied to the negative input terminal. On the other hand, a reference voltage obtained by dividing the operating voltage Vcc by the resistors R4 and R5 is applied to the positive input terminal of the voltage comparator CP via the resistor R1.

  When the generator motor 1 is rotating at a low speed and the voltage applied to the negative input terminal of the voltage comparator CP is smaller than the reference voltage, a high level signal is output from the voltage comparator CP. This signal is input to one input terminal of each of the AND circuits 94 and 96. Two types of synchronous rectification control signals output from the synchronous rectification control signal generation circuit 90 are separately input to the other input terminals of the AND circuits 94 and 96. Therefore, when a high level signal is output from the voltage comparator CP in the frequency-voltage conversion control circuit 92, the signal is input from the synchronous rectification control signal generation circuit 90 from each output terminal of the AND circuits 94 and 96. The synchronous rectification control signal is output as it is. These synchronous rectification control signals are input to the MOS-FET 5c or 5f.

  Further, when the rotational speed of the generator motor 1 rises to a predetermined rotational speed or more and the voltage applied to the negative input terminal of the voltage comparator CP becomes higher than the reference voltage, a low level signal is output from the voltage comparator CP. Output as a synchronous rectification stop signal. When the synchronous rectification stop signal is input to the AND circuits 94 and 96, the AND circuits 94 and 96 block the synchronous rectification control signal input from the synchronous rectification control signal generation circuit 90. For this reason, synchronous rectification control is stopped. In this case, rectification by a parasitic diode is performed instead of the synchronous rectification performed by turning on and off the MOS-FETs 5c and 5f.

Next, a method for setting the predetermined rotation speed for stopping the synchronous rectification control will be described. Figure 4 is a graph showing the relationship between the forward voltage drop V _F and the forward current I _F of the parasitic diode, the relationship between the drain-source voltage V _DS and the drain-source current I _D of the MOS-FET is there. As shown in FIG. 4, the drain-source voltage V _DS and the drain-source current I _D of the MOS-FET have a substantially linear relationship, and the drain-source current I _D increases as the drain-source current I _D increases.・ The source-to-source voltage V _DS gradually increases. On the other hand, the forward voltage drop V _F of the parasitic diode is almost constant. Therefore, when the output current of the generator motor 1 rises with the rotation rise to exceed when the MOS-FET5a~5f the drain-source voltage V _DS is the forward voltage drop V _F of the parasitic diode The rotational speed corresponding to this time is set as a predetermined rotational speed for stopping the synchronous rectification control.

  FIG. 5 is a diagram showing the relationship between the output of the generator motor 1 and the rectifying operation switching. In FIG. 5, an output characteristic curve OUT1 indicated by a solid line indicates the relationship between the rotational speed and the output current when synchronous rectification is performed in the entire rotational region. Further, an output characteristic curve OUT2 indicated by a dotted line shows the relationship between the output current of the rotational speed when rectification is performed by a parasitic diode in the entire rotational region.

As described with reference to FIG. 4, the output current is smaller in the rotation speed region lower than the predetermined rotation speed (Nc in FIG. 5), and the drain-source voltage V _DS of the MOS-FETs 5a to 5f is in the order of the parasitic diode. It is smaller than the forward voltage drop V _F. For this reason, in the low rotation speed region from the rotation speed Nin at which power generation is started to the predetermined rotation speed Nc, the output current becomes larger when synchronous rectification is performed. Meanwhile, since the output current is increased in the high rotation region above the predetermined rotation speed Nc, greater than the forward voltage drop V _F of the parasitic diode towards the drain-source voltage V _DS of MOS-FET5a~5f. For this reason, in the high rotation speed region from the predetermined rotation speed Nc to the maximum rotation speed, the output current becomes larger when the rectification by the parasitic diode is performed without performing the synchronous rectification.

  Since the resistor R3 is connected between the negative input terminal and the output terminal of the voltage comparator CP in the frequency-voltage conversion control circuit 92, the rotational speed increases and the synchronous rectification control is stopped. The rotational speed Nc ′ at which the synchronous rectification control, which has been stopped until then, is reduced is set lower than the predetermined rotational speed Nc. In this way, by providing hysteresis in the output and stop timing of the synchronous rectification stop signal, when the rotational speed fluctuates in the vicinity of the rotational speed Nc, frequent stop and restart of the synchronous rectification control are prevented. ing.

  That is, in the present embodiment, it can be said that not only the predetermined rotation speed Nc but also the rotation speed range from Nc ′ to Nc is set as the timing for switching the operation state of the synchronous rectification. If it is not necessary to provide hysteresis, the resistor R3 connected between the negative input terminal and the output terminal of the voltage comparator CP may be omitted.

  FIG. 6 is a diagram showing output characteristics of the generator motor 1 of the present embodiment. As shown in FIG. 6, in the low rotation speed region of the predetermined rotation speed Nc or less, the output characteristic A obtained by the synchronous rectification using the MOS-FETs 5a to 5f is not the output characteristic C obtained by the rectification using the parasitic diode. can get. As a result, in the low rotation region, the output increases as indicated by F with respect to the output characteristic C obtained by rectification using a parasitic diode.

  On the other hand, in the high rotation speed region of the predetermined rotation speed Nc or more, the output characteristic D obtained by rectification using a parasitic diode is obtained instead of the output characteristic B obtained by synchronous rectification using the MOS-FETs 5a to 5f. As a result, in the high rotation region, the output increases as indicated by G with respect to the output characteristic B obtained by the synchronous rectification using the MOS-FETs 5a to 5f.

  As described above, in the generator motor 1 of the present embodiment, the rectification operation by the parasitic diode and the synchronous rectification operation by the MOS-FET can be properly used, so that the output reduction is prevented in all the rotation regions and the power generation characteristics are improved. Can be achieved. In particular, by performing synchronous rectification using a MOS-FET with less loss in a low rotation region below a predetermined rotation number, and performing rectification using a parasitic diode with less loss in a high rotation region above a predetermined rotation number, It is possible to improve the power generation characteristics by preventing a decrease in output in all the rotation regions. In addition, by providing hysteresis as a predetermined rotation range for switching the operation state of synchronous rectification, it is possible to prevent frequent switching of the operation state of synchronous rectification when the number of rotations of the generator motor 1 increases or decreases in the vicinity of the predetermined rotation number. It is possible to prevent the rectification operation from becoming unstable.

In addition, this invention is not limited to the said embodiment, A various deformation | transformation implementation is possible within the range of the summary of this invention. For example, in the above-described embodiment, the synchronous rectification operation state is switched at a constant predetermined rotation speed Nc (or a range of Nc ′ to Nc). However, the output current increases or decreases depending on the temperature of the generator motor 1, and the order of parasitic diodes increases. Since the rotational speed at which the relationship between the directional voltage drop V _F and the drain-source voltage V _DS of the MOS-FET is reversed changes, the operation state of the synchronous rectification is considered in consideration of the fluctuation of the output characteristics due to the temperature of the generator motor 1 A predetermined number of rotations or a predetermined range of rotation may be set. For this setting, for example, the resistance values of the resistors R2 and R3 in the frequency-voltage conversion control circuit 92 may be varied according to the temperature. As a result, even when the temperature changes, a rectification operation with little loss is always possible, and even when the output characteristics fluctuate due to a temperature change, the rectification operation with the least loss can always be performed.

  In the above-described embodiment, the generator motor that performs the electric operation and the power generation operation has been described. However, the present invention can also be applied to a vehicle AC generator that performs only the power generation operation. In the above-described embodiment, the synchronous rectification control signal is generated based on the phase voltage. However, the rotational position of the rotor is detected by the sensor, and the synchronous rectification control signal corresponding to the detected rotational position is generated. You may do it.

It is a figure which shows the structure of the generator motor of one Embodiment. It is a figure which shows the modification of a generator motor. It is a figure which shows the specific structure of an inverter control circuit. It is a figure which shows the relationship between the forward voltage drop of a parasitic diode, and a forward current, and the relationship between the drain-source voltage and drain-source current of MOS-FET. It is a figure which shows the relationship between the output of a generator motor, and rectification operation switching. It is a figure which shows the output characteristic of the generator motor of this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Generator motor 2 Armature winding 3 Field winding 4 Three-phase inverter 5a, 5b, 5c, 5d, 5e, 5f MOS-FET
DESCRIPTION OF SYMBOLS 7 Control apparatus 8 Reference voltage adjustment circuit 9 Inverter control circuit 10 Battery 11 Frequency-voltage converter 90 Synchronous rectification control signal generation circuit 92 Frequency-voltage conversion control circuit 94, 96 AND circuit

Claims (6)

Field windings to magnetize the rotor field poles;
An armature that induces an alternating voltage by a rotating magnetic field generated by the field pole;
A rectifier that performs synchronous rectification and converts the alternating voltage induced in the armature into direct current;
A control device for switching the operation state of the synchronous rectification at a predetermined rotation speed or a predetermined rotation range;
A vehicular rotating electrical machine comprising: In claim 1,
The rectifier is composed of a plurality of switch elements having parasitic diodes,
When switching the operation state of the synchronous rectification at the predetermined rotational speed, the predetermined rotational speed is obtained by using an output characteristic curve when performing the rectifying operation using the parasitic diode and the switch element excluding the parasitic diode. A rotating electrical machine for a vehicle, characterized in that the rotational speed is set to overlap with an output characteristic curve when performing a rectifying operation. In claim 1,
When the operation state of the synchronous rectification is switched in the predetermined rotation range, the predetermined rotation range is determined by using an output characteristic curve when the rectification operation is performed using the parasitic diode and the switch element excluding the parasitic diode. A vehicular rotating electrical machine characterized in that a hysteresis is set in a range in which the output characteristic curve when the rectifying operation is performed overlaps with the rotation speed. In claim 1,
The control device causes the rectifier to perform synchronous rectification in a rotation region from a rotation speed at which power generation is started to the predetermined rotation speed when the operation state of the synchronous rectification is switched at the predetermined rotation speed. Rotating electric machine for vehicles. In claim 4,
The control device causes the rectifier to perform full-wave rectification by a parasitic diode included in the switch element in a rotation region from the predetermined rotation speed to the maximum rotation speed. In any one of Claims 1-5,
The rotating electrical machine for a vehicle according to claim 1, wherein the predetermined rotation speed or the predetermined rotation range for switching the operation state of the synchronous rectification is set in consideration of variation in output characteristics due to temperature.

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