JP2002153096A - Inverter controller for alternating-current motor- generator for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an alternating-current motor-generator controller for vehicle that makes it possible to avoid breakdown of a switching element, reduce switching loss, and suppress increase in noise through simple circuitry. SOLUTION: An alternating-current motor-generator 3 giving and receiving power to and from an engine 5 through a clutch 4 and driving equipment, not shown, mounted in the vehicle is supplied with electric power from an inverter 1. The inverter 1 is PWM-controlled with a low carrier frequency when the engine 5 is started, and with a high carrier frequency when the equipment mounted in the vehicle is driven.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an inverter control device for an AC motor generator for a vehicle.

[0002]

2. Description of the Related Art When inverter control is performed on a conventional AC rotating electric machine, the PWM carrier frequency thereof is sufficiently high to reduce noise (usually 10 to 1).
5 kHz).

[0003] However, increasing the PWM carrier frequency increases the power loss (switching loss) of the switching element of the inverter, and increases the possibility of destruction of the switching element. This is because the turn-on power loss is relatively small because the turn-on current is large but the turn-on resistance is small, and the switching loss during the transition period is relatively large because the turn-on resistance is large while the turn-on current is relatively small.

[0004] Japanese Patent Application Laid-Open No.
Japanese Patent Application Laid-Open No. 295278/1990 discloses that the temperature and current of a switching element are measured, and the PWM carrier frequency of the inverter is reduced at a predetermined temperature or a predetermined current value or more, so that the destruction of the switching element is prevented and the switching loss is reduced. is suggesting.

However, the above-mentioned conventional PWM carrier frequency switching technology requires additional detection circuit systems such as temperature detection and current detection, and the possibility of destruction of the switching element when these detection circuit systems fail. It has the problem of increasing.

In addition, when operating at a low PWM carrier frequency, the PWM carrier frequency approaches the mechanical resonance frequency value of the AC rotary electric machine, and the noise increases.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has an inverter control apparatus for an AC motor generator for a vehicle capable of realizing avoidance of switching element destruction, reduction of switching loss and suppression of noise increase with a simple circuit configuration. Is the issue to be solved.

[0008]

According to a first aspect of the present invention, there is provided an inverter control device for an AC motor generator for a vehicle, wherein the AC motor generator is configured to exchange power with an engine intermittently and to drive a vehicle-mounted device; An inverter arranged between the motor and a battery to perform orthogonal bidirectional power conversion, and control means for controlling the inverter, wherein the control means causes the AC motor generator to start the engine when the engine is started. A start mode that operates as a motor for power generation, a power generation mode that operates the AC motor generator as a generator after the start of the engine is completed, and the engine and the power transmission means when the engine is stopped. A vehicular generator motor control device for switching between a vehicular device driving mode for driving the vehicular device and the vehicular device. In the dynamic mode, the inverter is driven at a first PWM carrier frequency, and in the start mode, the inverter is driven at a second PWM carrier frequency lower than the first PWM carrier frequency. It is characterized by doing.

According to the present invention, in an AC motor generator for a vehicle which performs engine start and vehicle-mounted equipment drive (for example, at the time of an idle stop at an intersection) in addition to power generation, the largest current flows through the switching element of the inverter and the switching element It is noted that the highest temperature is obtained when the engine is started.

Therefore, when the PWM carrier frequency is lowered in the engine start mode in which a much larger current is supplied to the switching element than in the on-vehicle equipment driving mode, heat generation of the inverter switching element is suppressed. be able to. At the time of starting the engine, the noise of the vehicle alternator increases due to the decrease of the PWM carrier frequency,
Since the period for starting the engine is short and the noise of the engine itself is also large, the total noise is not so large in the theory of hearing. Furthermore, since the engine start period can be determined by the output signal of the existing detection means such as an ignition switch and a rotation speed sensor, no additional detection circuit system such as a current sensor or a temperature sensor is required, and the circuit configuration becomes complicated and the No measures to ensure reliability are required. In the on-vehicle equipment driving mode, the inverter is operated at a high PWM carrier frequency, but the current is small, so that it is possible to reduce the noise while preventing the switching element from overheating. In addition, in-vehicle equipment driving mode
Since the noise of the vehicle alternator is noticeable in the auditory theory because the engine is stopped in the vehicle, the reduction is particularly effective. The PWM carrier frequency in the in-vehicle device driving mode is, for example, 15 KHz in order to make the noise of the vehicle alternator higher than the audible frequency range.
The above is public.

In a preferred embodiment, in the power generation mode, it is preferable to set the PWM carrier frequency to be high as in the vehicle equipment drive mode. For example, PWM of power generation mode
The carrier frequency is the same as in the in-vehicle equipment drive mode,
The value may be higher than the PWM carrier frequency in the engine start mode and lower than that in the in-vehicle device driving mode.

According to a second aspect of the present invention, in the inverter control device for an AC motor generator for a vehicle according to the first aspect, the first PWM carrier frequency further includes a predetermined mechanical resonance frequency of the AC motor generator. And the second PWM carrier frequency is set lower than the predetermined mechanical resonance frequency value.

In this manner, the PWM carrier frequency can be largely changed without interfering with the mechanical resonance frequency value of the automotive alternator in both the on-vehicle equipment driving mode and the engine starting mode. The switching loss in the mode can be greatly reduced, and the noise in the in-vehicle device driving mode can be reduced favorably.

According to a third aspect of the present invention, in the inverter control apparatus for an AC motor generator for a vehicle according to the second aspect, the mechanical resonance frequency value is a claw of a rotor of the AC motor generator of a Landel type. It consists of the mechanical resonance frequency value of the magnetic pole part.

In the Landel type vehicle alternator, the resonance frequency of the claw-shaped magnetic pole portion of the rotor iron core is 5 to 8 KHz. ), The PWM carrier frequency in the start mode is set to a lower value (for example, 3
KHz), it is possible to suitably achieve both noise suppression and prevention of thermal damage of the switching element.

According to a fourth aspect of the present invention, in the inverter control apparatus for an AC alternator for a vehicle according to the second or third aspect, the control means further comprises: a control unit configured to control the rotational speed of the engine based on an idle rotational speed value of the engine. The PWM carrier frequency is set to the second carrier when the value is lower than the low predetermined value and in the engine start mode.

According to this configuration, when the engine is in the engine start mode (the engine speed is less than the idle speed value of the engine) and is less than the predetermined value which is less than the idle speed value, the engine start mode is low. The PWM carrier frequency is reduced only in the engine speed band.

In the engine start mode, a large current flows through the switching element of the inverter at the beginning of the engine start mode, and the switching loss at this time is reduced. As a result, in the later stage of the engine start mode in which the current decreases from the initial stage of the engine start mode, the PWM
By increasing the carrier frequency, noise can be reduced without fear of destruction of the switching element.

According to a fifth aspect of the present invention, in the inverter control device for an AC motor generator for a vehicle according to the second or third aspect, the control means further comprises: And in the engine start mode, the PWM carrier frequency is set to the second carrier.

With this arrangement, when a large current flows through the switching element, the PWM carrier frequency is reduced to a value less than the mechanical resonance frequency of the predetermined portion of the automotive alternator, particularly preferably the claw-shaped magnetic pole portion. It is possible to suppress overheating of the switching element while suppressing noise increase due to mechanical resonance.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

1 is an inverter, 2 is a controller for inverter control, 3 is a rundle type AC motor generator for a vehicle, 4 is a clutch, 5 is an engine, and 6 is a rotational speed of the AC motor generator 3 for a vehicle. A rotation sensor, 7 is a current sensor, 8 is a vehicle electronic control unit (ECU) for controlling an engine (not shown), 9 is a vehicle-mounted battery, and 10 is a smoothing capacitor.

The inverter 1 is composed of a well-known three-phase inverter circuit composed of six switching elements (here, IGBT elements), and further includes a flywheel (not shown) individually connected in anti-parallel with each IGBT element. It has a wheel diode and an input smoothing capacitor C. A pair of DC input terminals of the inverter 1 exchange DC power with the battery 9, and a three-phase AC terminal of the inverter 1 is connected to the AC motor generator 3.
It exchanges AC power with three-phase armature coils.

The controller 2 includes a microcomputer 21 and a transistor 22 for switching a field current.
And a flywheel diode 23. In this embodiment, the controller 2 is constituted by a microcomputer in order to facilitate the understanding of the operation, but it goes without saying that the controller 2 may be constituted by a hardware circuit. Microcomputer 21
Reads a rotation signal of the vehicle alternator 3 detected by the rotation sensor 6, a predetermined one-phase AC current of the inverter 1 detected by the current sensor 7, and a battery voltage + B, based on a command from the vehicle ECU 8. Each IGB of inverter 1
T is subjected to PWM control, and the transistor 22 is further P-controlled to adjust the field current supplied to the field coil 31 of the vehicle alternator 3.

The vehicle alternator 3 is connected to an engine 5 via a clutch 4 so as to be able to exchange power. The rotor core of the Landel type vehicle alternator 3 has a core portion fitted and fixed to a rotating shaft, and an even number of claw shapes arranged at a constant pitch in a circumferential direction inside the stator core in a radial direction. A magnetic pole portion, the odd-numbered claw-shaped magnetic pole portions extend in the axial direction from one axial end of the core portion, and the even-numbered claw-shaped magnetic pole portions extend in the axial direction from the other axial end of the core portion. ing. A field coil 31 is wound around the core.

The current sensor 7 may be omitted, or may be replaced with another electric quantity having a correlation with the current of the vehicle alternator 2.

Since the circuit configuration itself is already well known, detailed description is omitted, and the microcomputer 2
1 will be described below with reference to the flowchart of FIG.

First, a detection signal of each sensor, a battery voltage, and a command of the vehicle ECU 8 are read (S100), and an optimum operation mode is selected based on the read signal (S102).
If the operation mode is the engine start mode, the process proceeds to step S104 to execute the engine start mode, and the in-vehicle device driving mode is performed.
If it is, the process proceeds to S106 to execute the in-vehicle device driving mode, and if it is the power generation mode, the process proceeds to S108 to execute the power generation mode.

The engine start mode means a control operation of the vehicle alternator 2 during an ON state of an ignition switch (not shown) detected directly or through the vehicle ECU 8, but instead of the ON state of the ignition switch, A period from when the ignition switch is turned on to when the engine speed reaches a predetermined value may be set as the engine start mode period. In the engine start mode of this embodiment, the microcomputer 21 determines a predetermined phase angle (electric mode) based on the rotational position of the rotor of the automotive alternator 2 input from the rotation sensor 6 and its rotational speed. The inverter 1 is subjected to PWM (pulse width modulation) control so that a three-phase AC voltage having a matching frequency is output to the vehicle AC generator 2. The duty ratio of the PWM control can be controlled so that the current target value matches the current value detected by the current sensor 7.

The on-vehicle device driving mode is an operation mode in which the vehicle ECU 8 drives a predetermined on-vehicle device (for example, a vehicle air-conditioning compressor) while the clutch 4 is disengaged. ,And,
This is carried out when a switch for operating a predetermined vehicle-mounted device (for example, a vehicle air-conditioning compressor) is electrically read. In the in-vehicle device driving mode of this embodiment, the microcomputer 21 performs PWM control on the inverter 1 so that the rotation speed of the vehicle alternator 2 read from the rotation sensor 6 is set within a predetermined range. The PW is set so that the current target value matches the current value detected by the current sensor 7.
It is also possible to control the duty ratio of the M control.

The microcomputer 21 executes the PWM control in each switching element of the inverter 1 in the engine start mode and the on-vehicle device driving mode, and is used for the PWM control in the engine start mode. The carrier frequency is f1 (here, 3 to 4 kHz), and the carrier frequency used for PWM control in the in-vehicle device driving mode is f2 (here, 13 to 16 kHz).

The power generation mode is an operation mode in which the vehicle alternator 2 charges the battery 9. The battery voltage is compared with a predetermined reference voltage value, and the transistor 22 is intermittently controlled based on the comparison result. To adjust the field current to converge the battery voltage to the reference voltage value. In the power generation mode, the power output generated by the vehicle alternator 2 is generated by the inverter 1.
Are subjected to three-phase full-wave rectification by diodes (not shown) individually and anti-parallel connected to the respective switching elements, and are sent to the battery 9. The microcomputer 21 is a transistor 2
2 is turned on 100%, but it is preferable that the transistor 22 is subjected to PWM control as the rotation speed increases, and the duty ratio thereof is gradually reduced to lower the generated voltage of the vehicle AC generator 2.

The power generation mode can be implemented by using a well-known alternator regulator circuit instead of controlling the transistor 22 by the microcomputer 21. However, when this regulator circuit is employed, this regulator circuit turns on the transistor 22 in the engine start mode by 100% and turns on the transistor 22 in the on-vehicle equipment driving mode by 100% or a predetermined duty ratio. Is subjected to PWM control.

(Effects of the Embodiment) The mechanical resonance frequency of the commonly used Landel type vehicle alternator 2 is 5 kHz to 9 kHz.
Hz range. Therefore, in this embodiment, the PWM carrier frequency in the engine start mode is set to be lower than the mechanical resonance frequency range, and set to a range exceeding the mechanical resonance frequency range in the in-vehicle device driving mode.

Thus, mechanical resonance of the vehicle alternator 2 is avoided, audible noise is reduced in the on-vehicle equipment driving mode, and heat generation of the switching element of the inverter 1 in the engine starting mode is reduced. I was able to.

FIG. 3 shows the mechanical vibration characteristics of the claw-shaped magnetic pole portion of the commercial AC generator for a vehicle having several claw-shaped magnetic pole portions and the inverter 1.
Shows the relationship with the output frequency.

(Modification) In this modification, steps S110, S112, and S114 shown in FIG. 4 are added between steps S102 and S104 shown in FIG.

In step S110, when the current i read from the current sensor 7 exceeds the predetermined threshold value ith,
Proceeding to step S112, the rotational speed is set to the predetermined threshold Nth.
The process proceeds to S104 if it is exceeded, otherwise proceeds to S114, fixes the PWM carrier frequency to 15 kHz, and proceeds to S114. Note that either step S110 or S112 may be omitted.
In this manner, noise during the latter period of the current reduction or the period of increase in the number of revolutions in the engine start mode can be reduced while suppressing overheating of the switching element.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram of a vehicular generator motor control device according to a first embodiment.

FIG. 2 is a flowchart showing a control operation of the microcomputer of FIG.

FIG. 3 is a characteristic diagram showing a vibration characteristic of a rundle type vehicle alternator.

FIG. 4 is a flowchart showing a modified embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Inverter 2 Controller (control means) for inverter control 3 Randell type vehicle AC motor generator 4 Clutch 5 Engine 6 Rotation sensor 7 Current sensor 8 Vehicle electronic control unit (ECU) 9 In-vehicle battery

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) CC18 CC24 CD01 CD03 CE05 EA01 EA10 FA01 FA08 FB02 FC12 FC17 FC22 GA09 GB05 HA04 HA27 JA02 JA19 JB15

Claims (5)

[Claims] An AC motor generator for intermittently transmitting and receiving power to and from an engine and for driving an on-vehicle device; an inverter disposed between the AC motor generator and a battery to perform orthogonal bidirectional power conversion; Control means for controlling an inverter, wherein the control means operates the AC motor generator as the motor for starting the engine when the engine is started.
A power generation mode for operating the AC motor generator as a generator after the start of the engine is completed, and a vehicle mounted for separating the engine and the power transmission means and driving the vehicle-mounted device when the engine is stopped. In a vehicle generator motor control device for switching between a device driving mode and a vehicle driving device, the control means drives the inverter at a first PWM carrier frequency in the vehicle driving device driving mode, and
In the start mode, the inverter is connected to the first PWM.
An inverter control device for an AC alternator for a vehicle, wherein the inverter is driven at a second PWM carrier frequency lower than the carrier frequency. 2. The inverter control device for an AC motor generator for a vehicle according to claim 1, wherein the first PWM carrier frequency is set higher than a predetermined mechanical resonance frequency value of the AC motor generator. 2
Wherein the PWM carrier frequency is set lower than the predetermined mechanical resonance frequency value. 3. The inverter control device for an AC motor generator for a vehicle according to claim 2, wherein the mechanical resonance frequency value is a mechanical resonance frequency value of a claw-shaped magnetic pole portion of a rotor of the rundle type AC motor generator. An inverter control device for an AC alternator for a vehicle, comprising: 4. The inverter control device for an AC alternator for a vehicle according to claim 2, wherein said control means is adapted to control a case where the engine speed is lower than a predetermined value lower than an idle speed value of said engine. An inverter control device for an AC alternator for a vehicle, wherein the PWM carrier frequency is set to the second carrier wave in an engine start mode. 5. The inverter control device for an AC alternator for a vehicle according to claim 2 or 3, wherein said control means is provided when said current of said AC alternator is equal to or more than a predetermined value and in an engine start mode. The inverter control device for an AC motor generator for a vehicle, wherein the PWM carrier frequency is set to the second carrier wave.