JP3289870B2 - Three-phase synchronous motor controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a starting and torque assisting device for a vehicle internal combustion engine.

[0002]

2. Description of the Related Art Japanese Patent Laying-Open No. 61-38161 discloses that a single brushless motor directly connected to an output shaft of an engine is used to start an engine and accelerate a vehicle, and otherwise operates as a generator. A starting and torque assist device for an internal combustion engine for a vehicle has been proposed.

[0003] In addition, the suitability of various types of motors as traveling motors for electric vehicles is being studied, and DC motors, induction motors, three-phase synchronous motors, and the like are candidates.

[0004]

However, in the above-described vehicle internal combustion engine starting and torque assist device,
A single brushless motor must operate in a wide rotation speed range in order to start the engine and accelerate the vehicle, but in order to satisfy the voltage-current characteristics at startup (at low speed) of 200 rpm or less, the motor must The inductance (turns) of the armature coil must be increased. However, if the inductance (turns) of the armature coil is increased in this manner, the voltage due to the inductance is increased during acceleration at high rotation (1000 to 3000 rpm). There is a problem that the descent becomes excessively large and, as a result, the obtained electric output is substantially reduced and sufficient acceleration performance cannot be obtained.

This problem will be described with reference to an equivalent circuit for one phase in FIG. 3. V is an input phase voltage (AC voltage), R is the resistance of the armature coil, L is the inductance of the armature coil,
E is the back electromotive force of the armature coil, ω is the angular velocity, If is the field current, and K is the proportional constant.

[0006]

## EQU1 ## The following holds: E = k · ω · If. In the conventional control method, as shown in the vector diagram of FIG. 4, the phase of the back electromotive force E is detected by a magnetic pole position sensor or the like, and the phase of the input current (AC current) I becomes the same as that of the back electromotive force E. Thus, the input voltage V is controlled. Accordingly, when the angular velocity ω increases, the inductance jωLI increases, and the back electromotive force E decreases accordingly, and the electric output P = 3EI decreases extremely at high speed.

Of course, it is possible to reduce the above-mentioned problem by winding a plurality of armature coils and switching the series / parallel between them, but the circuit configuration and the armature configuration become complicated, and a shock at the time of switching occurs. A problem arises. The present invention has been made in view of the above-described problems, and a three-phase synchronous motor control device for starting and torque assisting a vehicle internal combustion engine capable of preventing a decrease in acceleration torque at high speed without reducing the starting torque. Its purpose is to provide.

As a running motor of an electric vehicle, a DC motor has a disadvantage that the starting torque is large but a commutator structure is complicated, while an induction motor has a disadvantage that the starting torque is relatively small. When the number of turns (inductance) of the armature coil is increased in order to increase the starting torque of the initial motor, the output of the armature coil decreases at high output current and high speed operation for the same reason as described above, and the electric output decreases. There was a problem of doing it.

Therefore, another object of the present invention is to provide a three-phase synchronous motor control device capable of reducing a decrease in output during high-speed operation while avoiding a decrease in starting torque of a three-phase synchronous motor for a traction motor of an electric vehicle. To provide. Further, the present invention is not limited to the above-described three-phase synchronous motor for engine start and torque assist for a vehicle or a three-phase synchronous motor for a traction motor of an electric vehicle, but also a three-phase synchronous motor having a wide range of rotation speed from low to high speed. Another object of the present invention is to reduce a torque decrease at a high speed while suppressing a torque decrease at a low speed in an electric motor.

[0010]

According to a first aspect of the present invention, there is provided:
An AC current is applied to the armature coil by converting the input DC voltage into an AC voltage having a desired frequency and phase and applying the converted voltage to an armature coil of a field coil type three-phase synchronous motor.
An inverter circuit to be energized; a rotation angle detection means for detecting a rotation angle of the three-phase synchronous motor; and a back electromotive force-related physical quantity detection means for detecting a back electromotive force-related physical quantity related to the back electromotive force of the three-phase synchronous motor. A field current control circuit that controls a field current that flows through a field coil of the three-phase synchronous motor; and a phase difference between the AC voltage and the AC current based on the detected back electromotive force-related physical quantity. Electric control for determining the frequency and phase of the AC voltage estimated to be equal to or less than a predetermined value or 0 and the respective command values of the field current, and driving the inverter circuit and the field current control circuit with the respective command values And a control means for performing an operation.

According to a second configuration of the present invention, in the first configuration, the three-phase synchronous motor is further connected to a vehicle engine to perform starting and torque assist of the vehicle engine. The control means performs the electric control operation when the torque assist is commanded. According to a third configuration of the present invention, in the first configuration, the three-phase synchronous motor is a traction motor of an electric vehicle, and the control unit controls the electric control at least when the three-phase synchronous motor rotates at a high speed. It is characterized by performing an operation.

[0012]

In the first configuration of the present invention, when controlling the phase angle and the field current of the AC voltage V applied to the field coil type three-phase synchronous motor, the AC voltage V and the armature coil are controlled. Is determined so that a phase difference (also referred to as a phase angle) with an alternating current I flowing through the motor becomes a predetermined value or less, preferably 0 (hereinafter referred to as VI common mode control).

In the present invention, there are various methods for realizing the above-mentioned VI common mode control, as will be described later.
If the in-phase control is realized, the back electromotive force E related to the mechanical output of the motor can be relatively large even at high speed (large frequency),
The motor output 3EI cos θ can be increased. Θ is the phase difference between the back electromotive force E and the AC current I, and in the case of VI in-phase, is naturally the VE phase difference. Although the power factor cos θ decreases as the rotation speed increases, in the present invention, the decrease in the back electromotive force E during high-speed rotation is smaller than the decrease in the power factor cos θ.
-I common-mode control) can increase the torque over a wider rotation speed range than the conventional EI common-mode control method.

Next, the above-mentioned VI common mode control will be described below with reference to the vector diagram of FIG. However, each waveform is assumed to be a sine wave. In the VI common mode control, the AC current I and the AC voltage V are changed by θ with respect to the back electromotive force E of the armature coil so that the applied AC voltage V and the supplied AC current I are in phase. Let go and control. In FIG. 5, the parameters to be controlled are the phase angle (phase difference) θ of V with respect to the phase of the back electromotive force E and the field current If. The scalar amount (magnitude) of the back electromotive force E can be controlled by controlling the field current If. Note that the scalar amount (magnitude) of the AC voltage V is fixed and invariable. (Determination of the phase of the back electromotive force E with respect to the rotational angle position (the angular position of the magnetic pole of the rotor)) First, the phase of the back electromotive force E with respect to the angular position of the magnetic pole of the rotor with the back electromotive force E (reference axis) ) Must be determined. There are two ways to do this.

The first method is to directly detect the phase or angle of the back electromotive force E. This includes winding a sensing coil on the armature core in the same phase as the armature coil,
Alternatively, since the back electromotive force E has a phase difference of 90 degrees from the rotating magnetic field Φ, the phase of the back electromotive force E can be determined by detecting the phase of the rotating magnetic field Φ with a Hall element or the like. The second method is to indirectly estimate the phase or angle of the back electromotive force E. Physically, it is considered that the back electromotive force E has a phase difference of about 90 degrees with respect to the composite magnetic field vector of the field magnetic field vector by the field current If and the magnetic field (armature reaction magnetic field) vector by the AC current I. Can be. Here, since the armature reaction magnetic field is related to the alternating current I and the angular velocity ω, the phase (relative phase) of the back electromotive force E with respect to the angular position of the magnetic pole of the rotor (for example, the field magnetic field vector) is I And If, and can be obtained from a map, for example.

Next, it is necessary to determine the phase angle θ of the AC voltage V with respect to the phase of the back electromotive force E when VI is in phase. Regarding the phase angle θ, the following three equations hold. If cos θ, sin θ, and tan θ are determined by the following equations, θ is naturally determined. Hereinafter, the term size indicates an amplitude (scalar quantity). The magnitude of V is constant.

[0017]

## EQU2 ## cos θ = (V−RI) / E

[0018]

## EQU3 ## sin θ = E / ωLI

[0019]

Tan θ = ωLI / (V-RI) First, the phase angle θ at which the VI is in-phase is calculated from the magnitude of the detected AC current I and the magnitude of the back electromotive force E based on Equation 2. Map search can be performed. Further, the phase angle θ at which the VI is the same phase can be calculated or map-searched based on Expression 3 from the magnitude of the detected AC current I, the magnitude of the back electromotive force E, and the angular velocity ω.

Further, the phase angle θ at which the in-phase VI is obtained can be calculated from the magnitude of the detected AC current I and the angular velocity ω based on Equation 4 or a map search can be performed. A first VI common mode control example will be described based on the above analysis results. First, in this method, the vector of the back electromotive force E, that is, the phase and magnitude are directly detected. Next, if θ is calculated from the detected magnitudes of E and I by Expressions 2 and 3, the phase angle θ of V is determined.

Based on the above analysis results, the second VI
An example of the in-phase control will be described. First, in this method, the phase of the back electromotive force E, that is, the angle, is calculated from a function of I and If or estimated from a map. Then, the phase angle θ of V with respect to E is determined by the method of Expression 4. That is,
The phase angle θ that becomes the VI phase may be calculated from the magnitude of the detected AC current I and the angular velocity ω based on Expression 3, or may be searched from a map.

In the first and second control examples,
It is also possible to adjust the magnitude of the back electromotive force E, which is the basis of the control. For example, if the angular velocity ω changes, the back electromotive force E changes in proportion thereto. On the other hand, the back electromotive force E is the field current I
It is also approximately proportional to f. Therefore, the back electromotive force E and the angular velocity ω
And a map representing the relationship between the field current If and the field current If
The change in the back electromotive force E due to the angular velocity ω can be corrected with the field current If to make the back electromotive force E substantially constant.

In the first and second control examples,
The magnitude of the back electromotive force E can be adjusted to adjust the AC current I to a desired level for the purpose of output control, and for that purpose, the field current If can also be adjusted. A third example of VI common mode control will be described based on the above analysis results. Since the object of the present invention is to control VI to have the same phase, the AC current I may be detected and its phase θi may be set as the phase of the AC voltage V. In this embodiment, the AC current I can be increased or decreased by adjusting the field current If.

As described above, in the first control example, the vector values of the current I flowing to the armature coil and the back EMF of the three-phase synchronous motor are used as the back EMF related physical quantities. In this way, accurate VI common mode control is realized. In the second control example, the current I to the armature coil and the angular velocity ω are used as the back electromotive force related physical quantities. This simplifies the device configuration.

Further, in the third control example, only the vector value of the current I flowing to the armature coil is used as the back electromotive force related physical quantity. This further simplifies the device configuration. The second configuration of the present invention is used for at least torque assist of a three-phase synchronous motor that starts the vehicle engine and performs torque assist. By doing so, the torque at the time of torque assist can be increased without reducing the starting torque of the three-phase synchronous motor for both starting and torque assist.

The third configuration of the present invention is applied to a traveling motor of an electric vehicle. Since the rotation speed of the running motor of an electric vehicle constantly changes from start to high speed, according to the present invention, a good torque can be generated in each rotation speed range. FIG. 6 is a calculation example showing a change in electric output when the phase current (AC current I) is changed while the AC voltage V is kept constant at 3000 rpm with the torque assist for the vehicle engine by the three-phase synchronous motor. It can be understood that 1 [kw] is the highest in the EI common mode control, whereas the output of 4 [kw] or more can be extracted in the VI common mode control of the present invention.

[0027]

【Example】

(Embodiment 1) Hereinafter, an embodiment (second control example described above) of a vehicle engine starting and torque assist device to which the three-phase synchronous motor control device of the present invention is applied will be described with reference to the drawings.

FIG. 1 shows a block diagram of this apparatus. The engine 1 and a synchronous machine (field coil type three-phase synchronous motor) 2 are mechanically directly connected, and a mechanical load 3 reaching a tire (not shown) is connected to the synchronous machine 2. Reference numeral 4 denotes a driver (inverter circuit) that supplies AC power to the synchronous machine 2 and converts AC power generated by the synchronous machine into DC. 5 is a controller (control means) for controlling the driver 4, 6 is an arithmetic unit (ECU) for obtaining a control signal, and 7 is an engine 1
The rotation angle detecting means for detecting the angular velocity and the magnetic pole position (not shown) of the synchronous machine 2 and transmitting it to the controller 5 comprises an absolute rotary encoder in this embodiment.

Reference numeral 8 denotes a battery (power storage means) serving as a power source of the synchronous machine 2, 90 denotes a current sensor for detecting a current supplied to the synchronous machine 2, and 11 controls a field current supplied to a field coil of the synchronous machine. It is a transistor (If driver). FIG.
Is a circuit diagram of the synchronous machine 2 and the driver 4 and 91
Reference numerals 93 to 93 denote armature coils, 10 a field coil, 11 a transistor (field current control means) for controlling a current flowing through the field coil 10, and 12 a flywheel diode. S1 to S6 are semiconductor switches (IGBT in this embodiment) for controlling the current of the armature coils 91 to 93.
It is. D1 to D6 are flywheel diodes.

FIG. 3 shows an equivalent circuit for one phase of the synchronous machine 2. FIG. 4 shows a control vector diagram of the conventional control, and FIG. 5 shows a control vector diagram of the present invention. Hereinafter, the operation of the present invention will be described. (Electric Operation at Startup) At the start of the engine 1, the magnetic pole position is detected as shown in the vector diagram of FIG. 4, and control is performed so that the back electromotive force E and the input current I have the same phase. That is,
The rotation angle detecting means detects the magnetic pole position of the rotor.
Since the magnetic pole position of the rotor and the back electromotive force E have a constant phase angle, the phase of the back electromotive force E (that is, the phase angle with respect to the applied AC voltage V) can be determined from the magnetic pole position of the rotor. Therefore, the current detection sensor (not shown) detects the AC current I of a predetermined phase and controls the phase of the AC voltage V so that the phase becomes equal to the phase of the back electromotive force E. This is conventional EI in-phase control, and a detailed description thereof will be omitted. It should be noted that, even at the time of starting, there is no problem even if the VI common mode control described later is performed. (Electric operation at the time of torque assist) After the start, when the ECU 6 detects an acceleration state based on an input signal from an accelerator opening sensor (not shown), the input voltage is changed so that the AC voltage V and the AC current I have the same phase as shown in FIG. Control V. The VI common mode control will be described below. In this embodiment, the amplitude (maximum value) of the AC voltage V is constant. Of course, it is also possible to control it.

This control is the second of the VI common mode control described above.
The control example is performed. This control will be described below. Here, the software control is performed, but it is of course possible to perform the control by hardware. First, the position of the magnetic pole of the rotor is obtained from the input rotation angle. Next, the phase angle θe of the back electromotive force E with respect to the magnetic pole position is obtained. In this embodiment, the ROM of the controller 5 stores a ternary map of the phase angle θe, the AC current I, and the field current If,
Search is performed by introducing I and If to this.

Next, the phase angle θ of V with respect to E is expressed by the following equation (4).
Is determined by the following method. Here, Equation 4 showing the relationship between the phase angle θ that becomes the VI in-phase, the magnitude of the AC current I, and the angular velocity ω is stored in the ROM as a map, and I, ω
To search for θ. Thereby, the phase of the AC voltage V is determined. Next, when a large torque is required, the field current If is increased, and when it is desired to decrease the torque, the field current If is reduced. That is, if I and If are within the allowable range, the torque is adjusted by controlling If.

FIG. 7 is a flowchart showing the control operation of the controller 5. First, the rotation speed N is read from the rotation angle detection means 7 (100), and it is checked whether N is 0 (102). If it is 0, it is checked whether a start command has been input from the ECU 6 (104) and input. If so, the above-described start control is performed (106), and the routine proceeds to step 108. On the other hand, if N is not 0, the process jumps to step 108.

In step 108, it is checked whether or not an acceleration command (accelerator depression amount is equal to or more than a predetermined amount) is input from the ECU 6. If not, the three-phase synchronous motor is operated as a synchronous generator (alternator). Charge. This charging operation, that is, the power generation operation itself is the same as that of a normal vehicle power generation device, and the description is omitted. Meanwhile, EC
If an acceleration command has been input from U6, an acceleration control subroutine 110 described below is executed, and the routine returns to step 100.

Next, the acceleration control subroutine 110 will be described with reference to FIG. It is assumed that the ECU 6 receives the accelerator pedal depression amount A from the accelerator pedal depression sensor.
First, the accelerator pedal depression amount A is read from the ECU 6, and the angular velocity ω is extracted from the input signal from the rotation angle detecting means (1100), and the transistor 11 corresponding to the value of the field current If corresponding to the accelerator pedal depression amount A and ω is obtained. Is obtained from a map stored in the ROM of the controller 5 in advance, and is output to the transistor 11 (1102).

Next, the angular velocity ω and the magnetic pole position are read from the encoder 7 and the alternating current I is read from the current sensor 90 (1104).
A map search is performed for the VE phase angle θ, an AC voltage V having this phase angle θ is synthesized, and the synthesized AC voltage V is output to the driver 4 (1
106). (Embodiment 2) In the present invention, the torque assist control 110 of Embodiment 1 is performed by using the above-described first VI common-mode control example. Hereinafter, this control will be described with reference to the block diagram of FIG. 9 and the flowchart of FIG. Here, the software control is performed, but it is of course possible to perform the control by hardware.

FIG. 9 is obtained by additionally providing a back electromotive force sensor (back electromotive force related physical quantity detecting means) 9 in FIG.
Although the back electromotive force sensor 9 is the above-described Hall element in this embodiment, it may be a sensing coil wound together with the armature coil 93. Next, the flowchart of FIG. 10 will be described. First, the accelerator pedal depression amount A is read from the ECU 6, and the angular velocity ω is extracted from the input signal from the rotation angle detecting means (2100). The transistor 11 corresponding to the value of the field current If corresponding to the accelerator pedal depression amount A and ω Is obtained from a map stored in the ROM of the controller 5 in advance and output to the transistor 11 (21
02).

Next, the angular velocity ω and the magnetic pole position are read from the encoder 7, the back electromotive force E is read from the back electromotive force sensor 9, and the alternating current I is read from the current sensor 90 (21).
04), a map search of the VE phase angle θ based on the read information or a phase angle θ is calculated from Equations 1 and 2, and an AC voltage V having the phase angle θ is synthesized.
(2106).

(Third Embodiment) In the present invention, the torque assist control 110 of the first embodiment is performed by using the third VI common mode control example described above. Hereinafter, this control will be described with reference to the block diagram of FIG. 1 and the flowchart of FIG. Here, the software control is performed, but it is of course possible to perform the control by hardware.

First, the accelerator pedal depression amount A is read from the ECU 6, and the angular velocity ω is extracted from the input signal from the rotation angle detecting means (3100), and the angular velocity ω corresponds to the value of the field current If corresponding to the accelerator pedal depression amount A and ω. The on-duty of the transistor 11 to be performed is obtained from a map stored in the ROM of the controller 5 in advance, and output to the transistor 11 (31
02).

Next, the angular velocity ω and the magnetic pole position P are read from the encoder 7, the AC current I is read from the current sensor 90 (3104), and harmonics are removed from the read AC current I by a software low-pass filter to remove the AC current. I, the phase angle θ, and the time Δθ required for the signal processing is added to the phase angle θ to obtain the phase angle θ ′ of the AC voltage V.
Is obtained, and an AC voltage V having the obtained angular velocity ω, magnetic pole position P, and phase angle θ ′ is synthesized, and is output to the driver 4 (3106).

(Embodiment 4) In the above-mentioned embodiment, E
Although the -I in-phase control is performed, in the present embodiment, the VI in-phase control described in the first embodiment is performed during the electric operation regardless of the start or the torque assist. By doing so, there is no need to perform EI in-phase control, so that control is simplified. Therefore, in this embodiment, the current sensor 9 can be omitted.

That is, since ω is 0 or very small at the time of starting, θ = 0 and I = V / R. Of course, if I = V / R at this time is too large, the on-duty ratio of the driver 4 can be controlled so as to decrease V. (Embodiment 5) In the above embodiment, the VI in-phase control of the three-phase synchronous motor in starting or torque assisting the vehicle engine has been described. Next, an embodiment in which a field coil type three-phase synchronous motor using the VI in-phase control of the present invention is adopted as a traveling motor of an electric vehicle will be described below.

The same method as that shown in FIG. 8 can be employed for the VI common mode control itself.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a circuit diagram of a synchronous machine 2 and a driver 4 of FIG.

FIG. 3 is an equivalent circuit diagram of one phase of the synchronous machine 2.

FIG. 4 is a vector diagram of conventional EI in-phase control.

FIG. 5 is a vector diagram of VI common mode control of the present invention.

6 is a characteristic diagram comparing outputs of the conventional control of FIG. 4 and the control of the present invention of FIG. 5;

FIG. 7 is a flowchart illustrating a control operation according to the first embodiment.

FIG. 8 is a flowchart showing an acceleration control subroutine of FIG. 7;

FIG. 9 is a flowchart showing control of a driver 5 of the controller 5 of FIG.

FIG. 10 is a flowchart illustrating a control operation according to the second embodiment.

FIG. 11 is a flowchart illustrating a control operation according to the third embodiment.

[Description of Signs] 1 is an engine, 2 is a synchronous machine, 4 is a driver (inverter circuit), 5 is a controller, 6 is an arithmetic unit (ECU),
7 is a rotation sensor (rotation angle detecting means), 8 is a battery (power storage means), 91 to 93 are armature windings (armature coils), 10 is a field coil, and S1 to S6 are semiconductor switches of the inverter circuit 4 ( IGBT), 11 is a field current switching transistor (field current control circuit), 9 is a back electromotive force detection sensor (back electromotive force related physical quantity detecting means),
90 is a current sensor (back electromotive force related physical quantity detecting means).

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ identification code FI H02P 6/08 H02P 6/02 371Z 6/16 B60K 9/00 E (58) Fields surveyed (Int.Cl. ⁷ , DB name ) H02P 6/20 B60K 6/02 B60L 11/14 F02N 11/00 H02P 6/08 H02P 6/16

Claims (3)

(57) [Claims] [Claim 1 wherein said armature coil by applying a DC voltage input is converted into an AC voltage of desired frequency and phase armature coils of the field coil type three-phase synchronous motor
An inverter circuit for supplying an alternating current to the three-phase synchronous motor; a rotation angle detecting means for detecting a rotation angle of the three-phase synchronous motor; and a back electromotive force for detecting a back electromotive force related physical quantity related to the back electromotive force of the three phase synchronous motor. Related physical quantity detection means, a field current control circuit for controlling a field current supplied to a field coil of the three-phase synchronous motor, and the AC voltage and the AC current based on the detected back electromotive force related physical quantity. The command value of the frequency and phase of the AC voltage and the field current, which are estimated to be equal to or less than a predetermined value or 0, are determined, and the inverter circuit and the field current control circuit are controlled by the command values. A three-phase synchronous motor control device, comprising: a control unit that performs an electric control operation for driving. 2. The three-phase synchronous motor is connected to a vehicle engine for starting and torque assisting the vehicle engine, and the control means controls the electric motor when the torque assist is commanded. The three-phase synchronous motor control device according to claim 1, which performs a control operation. 3. The three-phase synchronous motor according to claim 1, wherein said three-phase synchronous motor is a traction motor of an electric vehicle, and said control means performs said electric control operation at least when said three-phase synchronous motor rotates at a high speed. Phase synchronous motor controller.