JP2003169490A - Motor control system, motor control apparatus, and control method of motor-driving inverter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the control method of an inverter for attaining a high utilization ratio for voltage. <P>SOLUTION: The motor control system includes a three-phase motor (1, 1'), an inverter 2 for feeding a three-phase voltage (v<SB>u</SB>, v<SB>v</SB>and v<SB>w</SB>), and a controller 12 for controlling the inverter 12. The controller 12 controls the inverter 2 for carrying out a step (a) of generating a first three-phase output wave formed of rectangular pulses in a non-synchronization PWM (pulse width modulation) control method and generating an output as the three-phase voltage (v<SB>u</SB>, v<SB>v</SB>and v<SB>w</SB>), and a step (b) of converting the three-phase voltage according to the interval of the rectangular pulses into a second three-phase output wave including a single rectangular pulse per half cycle. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an electric motor control system. The present invention particularly relates to an electric motor control system that supplies electric power to an electric motor by an inverter.

[0002]

2. Description of the Related Art Various control methods have been studied in order to appropriately control an inverter that supplies electric power to a three-phase AC motor such as a permanent magnet motor or an induction motor. For example, PWM (Pulse Width Modulation) control for generating a pseudo sine wave composed of rectangular pulses whose pulse width is modulated, synchronous 1-pulse control for generating an output wave containing a single rectangular pulse in a half cycle, etc. are known. . Further, the PWM control is classified into a synchronous PWM control in which a modulated wave and a carrier wave are synchronized, and an asynchronous PWM control in which the carrier wave is not synchronized.
Such various control methods are switched and used according to the characteristics required for the output wave, such as frequency and effective amplitude.

Japanese Patent Laid-Open No. 7-227085,
Japanese Unexamined Patent Publication No. 2000-152639) discloses a technique in a two-level inverter device for an electric vehicle, which aims to eliminate the timbre change of magnetic noise and to control the entire output voltage substantially continuously. The power converter according to the technique performs asynchronous PWM control in the bipolar mode in the low output voltage range, asynchronous PWM control in the overmodulation mode in the high output voltage range, and synchronous 1-pulse control in the maximum output voltage range. As a condition for shifting from the overmodulation mode to the synchronous 1-pulse control, there is disclosed a condition that the magnitude of the output voltage, the modulation rate, or the output voltage fundamental frequency becomes a predetermined value. The overmodulation mode means a state in which the modulation rate exceeds 1, and therefore, the published patent publications (JP-A-7-227085 and JP-A-2000-152639).
Shows the synchronous 1 from the asynchronous PWM control in which the modulation rate exceeds 1.
A control method for switching to control by pulse control is disclosed.

Japanese Patent Laid-Open No. 6-197550
Discloses a technique aiming at reducing a sudden voltage change when switching from the asynchronous PWM control to the synchronous 1-pulse control mode and reducing electromagnetic noise fluctuation during acceleration of the electric motor. The published patent publication (JP-A-6-197550) discloses
When switching from the asynchronous PWM control to the synchronous 1-pulse control mode, the control method of gradually decreasing the carrier frequency to switch to the synchronous 1-pulse control mode and the synchronous multi-pulse control mode of the intermediate carrier frequency are stepwise several times. A control method for switching to the synchronous 1-pulse control mode after passing through is disclosed.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide an inverter control technique having a higher voltage utilization rate.

Another object of the present invention is to provide an inverter control technique suitable for an electric motor control system using a battery as a DC power source.

[0007]

[Means for Solving the Problems] Means for solving the problems will be described below by using the numbers and symbols used in the embodiments of the present invention. These numbers / codes are added to clarify the correspondence between the description in [Claims] and the description in [Embodiment of the Invention]. However,
The added numbers / codes should not be used to interpret the technical scope of the invention described in [Claims].

The electric motor control system according to the present invention comprises a three-phase electric motor (1, 1 ') and an inverter (for supplying three-phase voltage (v _u , v _v , v _w ) to the three-phase electric motor (1, 1'). 2)
And a control device (12). Controller (1
2) is (a) asynchronous PWM (Pulse width modulatio
n) a step of generating a three-phase first output wave composed of rectangular pulses by control and outputting it as a three-phase voltage (v _u , v _v , v _w ); and (b) a pulse interval of the rectangular pulses. In response to the three-phase voltage (v _u , v _v , v _w ) is switched to a three-phase second output wave comprising a single rectangular pulse per half cycle. To control the inverter (2).

It is preferable that the modulation rate of the asynchronous PWM control is set to be less than 1.

The control unit (12) determines that the pulse interval is
It is preferable to have the inverter (2) execute the step (b) when it decreases to a predetermined value.

The control unit (12) determines that the pulse interval is
It is preferable to have the inverter (2) execute the step (b) when it is maintained at a predetermined value for a predetermined time.

The predetermined value is the switching element (8u, 8v, 8w, 9u, 9) included in the inverter (2).
v, 9w) is preferably set according to the switching speed.

The control device (12) is (c) the asynchronous P
In the WM control, among the voltage vectors of the first output wave supplied to the three-phase electric motor (1, 1 ′), the last voltage vector other than (000) and (111) before the step (b) is performed. And (d) determining the final voltage vector and the step of defining a switching voltage vector having a different value for only one phase.
And (e) the second voltage corresponding to the switching voltage vector.
The step of outputting the output wave is preferably executed by the inverter (2).

The inverter control method for driving an electric motor according to the present invention uses the inverter (2) to drive the three-phase electric motor (1,
1 ') is a motor drive inverter control method for supplying a three-phase voltage (v _u , v _v , v _w ). The motor drive inverter control method includes (a) asynchronous PWM (Pu
lse width modulation) control to generate a three-phase first output wave composed of rectangular pulses to generate a three-phase voltage (v _u , v
_v , v _w ), and (b) in response to the pulse interval of the rectangular pulse, the three-phase voltage (v _u ,
v _v , v _w ) to a three-phase second output wave configured to include a single rectangular pulse per half cycle.

A computer program according to the present invention is
The three-phase voltage (v _u , v _v ,
v _w ) is a computer program for controlling an inverter (2) that supplies v _w . The computer program includes (a) an inverter (2), an asynchronous PWM (Pu
Lse width modulation) control is performed to generate a three-phase first output wave composed of rectangular pulses, and a three-phase voltage (v _u ,
v _v , v _w ) and (b) in response to the pulse interval of the rectangular pulse, the inverter (2)
And switching the three-phase voltage (v _u , v _v , v _w ) to the three-phase second output wave configured to include a single rectangular pulse per half cycle.

[0016]

DETAILED DESCRIPTION OF THE INVENTION Referring to the accompanying drawings,
An embodiment of an electric motor control system according to the present invention will be described.

In one embodiment of the motor control system according to the present invention, as shown in FIG. 1, a permanent magnet motor 1 is provided together with an inverter 2. The rotor of the permanent magnet electric motor 1 is provided with a permanent magnet that generates a field magnetic flux. The armature of the permanent magnet motor 1 is provided with a u-phase armature coil, a v-phase armature coil, and a w-phase armature coil (not shown) that generate a rotating magnetic field.

The inverter 2 is connected to the battery 3 and is supplied with a DC power source potential from the battery 3. The inverter 2 receives the u-phase voltage v _u , the v-phase voltage v _v , from the DC power supply potential V _dc supplied from the battery 3.
And w-phase voltage v _w are generated and supplied to the u-phase armature winding, the v-phase armature winding, and the w-phase armature winding of the permanent magnet motor 1, respectively. u-phase voltage v _u , v-phase voltage v _v , and w
The supply of the phase voltage v _w is performed via the u-phase power supply line 4u, the v-phase power supply line 4v, and the w-phase power supply line 4w, respectively.

More specifically, the inverter 2 includes a power supply line 6, a power supply line 7, switching transistors 8u, 8v,
8w and switching transistors 9u, 9v, 9
w, including the smoothing capacitor 10. The power supply line 6 and the power supply line 7 are connected to the battery 3, and the power supply line 6 has a power supply potential V
_{At dc} , the power supply line 7 is held at 0 voltage. The switching transistors 8u, 8v, and 8w are provided between the u-phase power supply line 4u, the v-phase power supply line 4v, and the w-phase power supply line 4w, and the power supply line 6, respectively. Power line 4
The v- and w-phase power supply lines 4w are pulled up to the power supply potential V _dc . The switching transistors 9u, 9v, 9w are
The u-phase power supply line 4u, the v-phase power supply line 4v, the w-phase power supply line 4w, and the w-phase power supply line 4w are provided between the power supply line 7 and the u-phase power supply line 4u, respectively. 4w is pulled down to 0 potential. The smoothing capacitor 10 reduces the fluctuation of the power supply potential V _dc due to the on / off of the switching transistors 8u, 8v, 8w, 9u, 9v, 9w.

Current detectors 5u, 5v, and 5w are provided on the u-phase power supply line 4u, the v-phase power supply line 4v, and the w-phase power supply line 4w, which supply electric power from the inverter 2 to the permanent magnet electric motor 1, respectively. ing. The current detector 5u measures the u-phase current i _u flowing through the u-phase armature winding of the permanent magnet motor 1, and the current detector 5v measures the v-phase current i _v flowing through the v-phase armature winding. The current detector 5w measures the w-phase current i _w flowing through the w-phase armature winding.

The permanent magnet motor 1 is connected to the encoder 11. The encoder 11 detects the position θ of the rotor of the permanent magnet motor 1.

The current detectors 5u, 5v, 5w and the encoder 11 are connected to an MPU (Micro Processing Unit) 12. The MPU 12 has current detectors 5u, 5
u-phase current i _u and v-phase current i measured by v and 5 w, respectively
_v and w-phase current i _w , rotor position θ of permanent magnet motor 1 measured by encoder 11, d-axis current command (excitation current command) i _d ^* , and q-axis current command (torque command) i
A control calculation for controlling the inverter 2 is performed based on _q ^* . The clock signal CLK is supplied to the MPU 12,
The control calculation for controlling the inverter 2 is performed in synchronization with the supplied clock signal CLK. The MPU 12 has switching transistors 8u, 8v, 8w, 9u, 9v, and 9 included in the inverter 2 according to the result of the control calculation.
A switching command S for instructing on / off of w is generated. The switching command S is a switching signal S ^pu ,
Including S ^pv , S ^pw , S ^nu , S ^nv , and S ^nw ,
Switching signals S ^pu , S ^pv , S ^pw , S ^nu , S
^nv, and ^{S nw,} respectively, to instruct the switching transistor 8u, 8v, 8w, 9u, 9v, and on and off of 9w. Switching transistors 8u, 8v,
U corresponding to ON / OFF of 8w, 9u, 9v, and 9w
Rectangular pulses are output as the phase voltage v _u , the v phase voltage v _v , and the w phase voltage v _w .

FIG. 2 is a block diagram equivalently showing the control calculation performed by the MPU 12. MPU12 is equivalently
3-phase to 2-phase converter 21, subtractor 22, PI controller 23,
Subtractor 24, PI controller 25, 2-phase to 3-phase converter 26,
Asynchronous PWM calculator 27, synchronous 1 pulse control calculator 2
8 and a switch 29. Asynchronous PWM calculator 27
Are u-phase duty register 30u, v-phase duty register 30v, w-phase duty register 30w,
u phase upper timer 31u, u phase lower timer 3
2u, v phase upper timer 31v, v phase lower timer 32v, w phase upper timer 31w, w phase lower timer 32w are included. 3-phase to 2-phase converter 21, subtractor 22, PI controller 23, subtractor 24, PI controller 2
5, 2-phase to 3-phase converter 26, asynchronous PWM calculator 27,
The functions of the synchronous 1-pulse control calculator 28 and the switch 29 are actually realized by the MPU 12 executing a control computer program.

The three-phase / two-phase converter 21 includes a current detector 5
The d-axis current i _d and the q-axis current i _q are calculated from the u-phase current i _u , the v-phase current i _v , and the w-phase current i _w measured by u, 5v, and 5w, respectively. The position θ of the rotor required to calculate the d-axis current i _d and the q-axis current i _q is determined by the encoder 11
Given by. When calculating the d-axis current i _d and the q-axis current i _q , it is not necessary that all of the u-phase current i _u , the v-phase current i _v , and the w-phase current i _w be measured, and the u-phase current i _u ,
Two of the v-phase current i _v and the w-phase current i _w are measured, and the other one can be calculated from i _u + i _v + i _w = 0, ... (Equation (1)).

The calculated d-axis current i _d and q-axis current i _q
From, the d-axis voltage command value v _d ^* and the q-axis voltage command value v _q ^* are calculated, respectively. The d-axis voltage command value v _d ^* is calculated by the subtractor 22 and the PI controller 23, and the d-axis voltage command value v _d ^* is calculated by the following equation (2):

[Equation 1] ... Formula (2) Is calculated by Where I_d ^*, I_d, V_d ^*Is
D-axis current command value i_d ^*, D-axis current i_d,as well as
d-axis voltage command value v_d ^*Is the Laplace transform of _Pd,
K_IdAre the proportional gain and product of the PI controller 23, respectively.
Minute gain. Similarly, the q-axis voltage command value v_q ^*Calculation of
Is performed by the subtractor 24 and the PI controller 25, and the q-axis
Voltage command value v_q ^*Is the following formula (3):

[Equation 2] ... Formula (3) Is calculated by Where I_q ^*, I_q, V_q ^*Is
Q-axis current command value i_q ^*, Q-axis current i_q,as well as
q-axis voltage command value v_q ^*Is the Laplace transform of _Pq,
K_IqAre the proportional gain and product of the PI controller 25, respectively.
Minute gain. Calculated d-axis voltage command value v_d ^*, And
And q-axis voltage command value v_q ^*Is supplied to the 2-phase to 3-phase converter 26.
Be paid.

[0026] 2-phase three-phase converter 26, the d axis voltage value _v ^{d *} and the q-axis voltage command value _v ^{q *,} u-phase voltage command values _v ^u *, v-phase voltage command value _v ^v *, And w-phase voltage command value v
Calculate _w ^* . The encoder position 11 supplies the rotor position θ required to calculate the u-phase voltage command value v _u ^* , the v-phase voltage command value v _v ^* , and the w-phase voltage command value v _w ^* . The 2-phase / 3-phase converter 26 calculates the calculated u-phase voltage command value v _u ^* ,
The v-phase voltage command value v _v ^* and the w-phase voltage command value v _w ^*
Asynchronous PWM calculator 27 and synchronous 1 pulse control calculator 2
8 and supply.

Asynchronous PWM calculator 27 and synchronous 1 pulse
The control calculator 28 is a switch for controlling the inverter 2.
Independent command generation. Asynchronous PWM calculator 27
Is asynchronous PWM switching by asynchronous PWM control
Command S₁And the synchronous 1-pulse control calculator 28 generates
Synchronous 1 pulse switching command S by 1 pulse control
_TwoTo generate.

More specifically, the asynchronous PWM calculator 27
Performs an operation for performing asynchronous PWM control on the inverter 2 based on the u-phase voltage command value v _u ^* , the v-phase voltage command value v _v ^* , and the w-phase voltage command value v _w ^* , and performs the asynchronous PWM control. The switching command S ₁ is generated. Asynchronous P
The WM switching command S ₁ is a switching signal S ₁ ^pu , S _{1 for} instructing on / off of the switching transistors 8u, 9u, 8v, 9v, 8w, and 9w, respectively.
^nu , S ₁ ^pv , S ₁ ^nv , S ₁ ^pw , and S ₁ ^nw .

FIG. 3 shows switching signals S ₁ ^pu and S ₁
A method of generating ^nu will be shown. Switching signals S ₁ ^pu , S
_To generate ₁ ^nu , the u-phase duty register 30u is used.
, U-phase upper timer 31u and u-phase lower timer 32u are used.

The u-phase upper timer 31u and the u-phase lower timer 32u are both up / down counters simulating a triangular carrier wave used in asynchronous PWM control. The u-phase upper timer 31u and the u-phase lower timer 32u hold the u-phase upper counter value C _u ^U and the u-phase lower counter value C _u ^L , respectively.
u phase upper counter value _C ^{u U} increases or decreases between the maximum value ^C _{U M AX} and the minimum value ^C _{U MIN} at a predetermined carrier frequency _{f sc.} The u-phase lower counter value C _u ^L is the maximum value C
^The value between ^L _MAX and the minimum value C ^L _MIN is increased or decreased at the same frequency f _sc and phase as the u-phase upper counter value C _u ^U. The u-phase upper counter value C _u ^U is always larger than the u-phase lower counter value C _u ^L.

The u-phase duty register 30u is a register for simulating a modulated wave used in asynchronous PWM control, and stores the u-phase duty value D _u . The u-phase duty value D _u is used to generate the u-phase voltage v _u . u
Phase duty value D _u is one-to-one correspondence to the duty of the U-phase voltage v _u, the larger the u-phase duty value D _u, the duty of the duty of the U-phase voltage v _u also increases.

The asynchronous PWM calculator 27 increases or decreases the u-phase duty value D _u in response to the u-phase voltage command value v _u ^* . The larger the u-phase voltage command value v _u ^* , the larger the u-phase duty value D _u .

The switching signal S ₁ ^{pu for} instructing the switching transistor 8u to be turned on and off, respectively, includes the u-phase duty value D _u and the u-phase upper counter value C described above.
_u- phase duty value D generated based on the magnitude of _u ^U
_{When u} is greater than or equal to the u-phase upper counter value C _u ^U , the switching signal S ₁ ^pu is applied to the switching transistor 8
When the u-phase duty value D _u is less than the u-phase upper counter value C _u ^U , the switching signal S ₁ ^pu is generated so as to instruct the u to be turned on. .

Similarly, the switching transistor 9u
Switching signal S for instructing ON / OFF respectively₁ ^nu
Is the u-phase duty value D_uAnd u-phase lower counter value
C_u ^LIt is generated based on the size of. u phase duty
Value D_uIs the u-phase lower counter value C_u ^LIs above
Switching signal S₁ ^nuIs a switching transition
It is generated to instruct the star 9u to turn off.
Tee value D_uIs u phase upper counter value C_u ^UIs less than
The switching signal S₁ ^nuIs a switching tiger
It is generated to instruct the register 9u to turn on.

When the switching transistors 8u and 9u are turned on / off according to the switching signals S ₁ ^pu and S ₁ ^nu thus generated, the u-phase voltage v _u consisting of a rectangular pulse is generated.

The switching signals S ₁ ^pv and S ₁ ^{nv for} instructing on / off of the switching transistors 8v and 9v, respectively, are generated in the same manner as the switching signals S ₁ ^pu and S ₁ ^nu . Switching signals S ₁ ^pv , S
_To generate ₁ ^nv , a v-phase upper timer 31v and a v-phase lower timer 32v that simulate a triangular carrier, and a v-phase duty register 30v that simulates a modulated wave are used. The v-phase upper counter value C _v ^U and the v-phase lower counter value C _v ^L held by the v-phase upper timer 31 v and the v-phase lower timer 32 v, respectively, are the u-phase upper counter value C _u ^U and the u-phase, respectively. The phase changes with a delay of 120 ° from the lower counter value C _u ^L. v-phase upper counter value C _v ^U and v
The maximum value and the minimum value of the phase lower counter value C _v ^L are the same as the maximum value and the minimum value of the u-phase upper counter value C _u ^U and the u-phase lower counter value C _u ^L , respectively. v-phase duty register 30v holds v-phase duty value _{D v} is increased or decreased in response to the v-phase voltage command value _v ^{v *.} Switching signals S ₁ ^pv and S
₁ ^nv is generated based on the magnitude of the v-phase duty value D _v and the v-phase upper counter value C _v ^U, and the magnitude of the v-phase duty value D _v and the v-phase lower counter value C _v ^L , respectively. When the switching transistors 8v and 9v are turned on / off according to the switching signals S ₁ ^pv and S ₁ ^{n v} generated in this way, a v-phase voltage v _v composed of a rectangular pulse is generated.

The switching transistors 8w and 9w are turned on.
Switching signal S for instructing each to turn off₁ ^pwOver
And S₁ ^nwAlso the switching signal S₁ ^pu, S₁ ^nu,
And S₁ ^pvS₁ ^nvIs generated in the same way as. Switch
Teaching signal S₁ ^pw, S₁ ^{n w}To generate a triangular carrier
W-phase upper timer 31w and w-phase lower
-Timer 32w and w-phase duty to simulate modulated wave
Register 30w is used. w-phase upper timer
-31w and w-phase lower timer 32w are kept respectively.
Have, w-phase upper counter value C_w ^UAnd w phase lower
-Counter value C _w ^LAnd, respectively, u phase upper cow
Input value C_u ^UAnd u phase lower counter value C_u ^LStarting from
The phase changes with a delay of 240 °. w phase upper cow
Input value C_w ^UAnd w-phase lower counter value C_w ^LMaximum of
Value and minimum value are u phase upper counter value respectively
C_u ^UAnd u phase lower counter value C_u ^LMaximum value of and
It is the same as the minimum value. w-phase duty register 30w
W-phase duty value D held by_wIs the w-phase voltage command value
v_w ^*Is increased or decreased in response to. Switching signal S ₁
^pwAnd S₁ ^nwIs the w-phase duty value D
_wAnd w phase upper counter value C_w ^UBig and small, w phase de
Utility value D_vAnd w phase lower counter value C_w ^LWhen
It is generated based on the size of. Generated in this way
Switching signal S₁ ^pw, S₁ ^nwAccording to
When the ching transistors 8w and 9w are turned on and off,
W-phase voltage v consisting of a pulse_wIs generated.

The switching signals S ₁ ^pu , S ₁ ^pv , S ₁ ^pw , S ₁ ^nu , generated in this way,
Depending on S ₁ ^nv and S ₁ ^nw , u-phase voltage v _u , v-phase voltage v _v , and w-phase voltage v _w are u-phase armature coil, v-phase armature coil, and w-phase of permanent magnet motor 1. When output to the armature coil, the voltage between the two phases of the armature of the permanent magnet motor 1 becomes a pseudo sine wave, and the u-phase armature coil, the v-phase armature coil, and the w-phase armature coil generally have An armature current that is a sine wave flows.

Switching signals S ₁ ^pu , S ₁ ^nu , S
₁ ^pv , S ₁ ^nv , S ₁ ^pw , and u 1-phase duty value D _u , which is used to generate S ₁ ^nw , v-phase duty value D _v , and w-phase duty value D _w have a minimum value D _MIN and a maximum value D _MIN. The value D _MAX is defined, and the u-phase duty value D _u , the v-phase duty value D _v , and the w-phase duty value D _w can all take only values from D _{MIN to} D _MAX . In this case, the minimum value _{D MIN} and the maximum value ^{_{D MAX, C U MIN <D}} MIN, D MAX <C L MAX, destined to become, u-phase duty value _D u, v-phase duty value _D v, The w-phase duty value D _w is C ^U
It can only take values between _MIN and C ^L _MAX . This corresponds to the modulation rate in the non-modulation PWM control being less than 1.

The switching signals S ₁ ^pu , S ₁ ^nu , S ₁ ^pv , S ₁ ^nv , generated in this way,
The switching command S _{1 including} S ₁ ^pw and S ₁ ^nw is supplied to the switch 29.

On the other hand, the synchronous 1-pulse control calculator 28 calculates u-phase voltage command value v _u ^* , v-phase voltage command value v _v ^* , and w to perform the synchronous 1-pulse control for the inverter 2. Based on the phase voltage command value v _w ^* , the synchronous 1-pulse switching command S ₂ is generated. The synchronous 1-pulse switching command S ₂ is applied to the switching transistors 8u and 9
Switching signals S ₂ ^pu , S ₂ ^nu , and S _{2 for} instructing on / off of u, 8v, 9v, 8w, and 9w, respectively.
^{It is} composed of ^pv , S ₂ ^nv , S ₂ ^pw , and S ₂ ^nw .

More specifically, the synchronous 1-pulse calculator 28
Determines the phase of the rectangular pulse output to the u-phase voltage line 4u based on the u-phase voltage command value v _u ^* , and the switching transistors 8u and 8w are respectively output so that the rectangular pulse is output at the determined phase. The switching command signals S ₂ ^pu and S ₂ ^nu for instructing the on / off of are output.
Further, the synchronous 1-pulse calculator 28 determines that the v-phase voltage command value v _v ^*
Based on the above, the phase of the rectangular pulse output to the v-phase voltage line 4u is determined, and a switching command signal for instructing ON / OFF of each of the switching transistors 8v and 9v so that the rectangular pulse is output at the determined phase. S ₂
^pv and S ₂ ^nv are output. Similarly, the synchronous 1-pulse calculator 28 determines the phase of the rectangular pulse output to the w-phase voltage line 4w based on the w-phase voltage command value v _w ^* , and the rectangular pulse is output at the determined phase. As described above, switching command signals S ₂ ^pw and S ₂ ^nw for instructing on / off of the switching transistors 8w and 9w are output.

The switching signals S ₂ ^pu , S ₂ ^nu , S ₂ ^pv , S ₂ ^nv , generated in this way,
The synchronous 1-pulse switching command S _{2 including} S ₂ ^pw and S ₂ ^nw is supplied to the switch 29.

The switch 29 selects one of the asynchronous PWM switching command S ₁ and the synchronous 1-pulse switching command S _2, and supplies the selected one as the switching command S to the inverter 2. The switching transistors 8u, 9u, 8v, 9v, 8w, and 9w of the inverter 2 are turned on / off according to one of the asynchronous PWM switching command S ₁ and the synchronous 1-pulse switching command S ₂ . When the asynchronous PWM switching command S ₁ is selected, the inverter 2 is controlled by the asynchronous PWM control, and when the synchronous 1 pulse switching command S ₂ is selected, the inverter 2 is controlled by the synchronous 1 pulse control. That is, the switching between the asynchronous PWM control and the synchronous 1-pulse control is performed by the switch 29.

Switching between the asynchronous PWM control and the synchronous 1-pulse control by the switch 29 is performed by the above-mentioned u-phase duty value D.
_{It is performed according to u} , the v-phase duty value D _v , the w-phase duty value D _w , and the rotation speed ω _m of the permanent magnet motor 1. While the asynchronous PWM control is being performed, the switch 29
Monitors the u-phase duty value D _u , the v-phase duty value D _v , and the w-phase duty value D _w used in the asynchronous PWM calculator 27, and calculates the u-phase duty value D _u , the v-phase duty value D _v , And the control of the inverter 2 from asynchronous PWM control to synchronous 1 according to the w-phase duty value D _w
Switch to pulse control. On the other hand, while the synchronous 1-pulse control is being performed, the switch 29 monitors the rotation speed ω _m of the permanent magnet motor 1 and controls the inverter 2 from the synchronous 1-pulse control to the asynchronous PWM according to the rotation speed ω _m. Switch to control. The details of switching between the asynchronous PWM control and the synchronous 1-pulse control will be described later, and will not be described further.

In the electric motor control system having the above-mentioned structure, when the permanent magnet electric motor 1 is in the low rotation range,
Asynchronous PWM control is performed, and when the permanent magnet motor 1 is in the high rotation range, synchronous 1-pulse control is performed.

More specifically, when the permanent magnet motor 1 is started from the state where the rotation speed ω _m of the permanent magnet motor 1 is 0, the switch 29 unconditionally outputs the asynchronous PWM switching command S ₁ . Select, inverter 2 is asynchronous PW
The pseudo sine wave is supplied to the permanent magnet motor 1 under the control of the M control.

In order to increase the rotation speed ω _m of the permanent magnet motor 1, it is necessary to increase the effective voltage of the pseudo sine wave supplied to the permanent magnet motor 1. The increase in the effective voltage of the pseudo sine wave is caused by the u-phase power supply line 4u and the v-phase power supply line 4v, w.
Increase in duty of u-phase voltage v _u , v-phase voltage v _v , and w-phase voltage v _w , which are respectively output to the phase power supply line 4 _w , that is,
It is performed by increasing the u-phase duty value D _u , the v-phase duty value D _v , and the w-phase duty value D _w .

When the rotational speed ω _m of the permanent magnet motor 1 further increases, at least one of the u-phase duty value D _u , the v-phase duty value D _v , and the w-phase duty value D _w becomes the maximum value D _MAX. To reach.

The switching device 29 has a u-phase duty value D _u ,
v-phase duty value D _v and w-phase duty value D _w
When it detects that any of the above has reached the maximum value D _MAX , the switching command S is switched from the asynchronous PWM switching command S ₁ to the synchronous 1-pulse switching command S ₂ . As a result, the control of the inverter 2 is controlled by asynchronous PWM.
The control is switched to the synchronous 1-pulse control. It is actually possible to directly switch the control of the inverter 2 from the asynchronous PWM control to the synchronous 1-pulse control by increasing the inductance of the armature coil of the permanent magnet motor 1 within a design allowable range.

The u-phase duty value D _u , the v-phase duty value D _v , and the w-phase duty value D _w are respectively
Since the duty ratios of the u-phase voltage v _u , the v-phase voltage v _v , and the w-phase voltage v _w correspond one-to-one, from another perspective, the u-phase duty value D _u and the v-phase duty value D _v , And w-phase duty value D _w are respectively the u-phase power supply line 4u, the v-phase power supply line 4v, and the w-phase power supply line 4w,
The pulse intervals of the rectangular pulses included in the u-phase voltage v _u , the v-phase voltage v _v , and the w-phase voltage v _w are in one-to-one correspondence. Here, the pulse interval is the time between two consecutive rectangular pulses. The larger the u-phase duty value D _u , the larger the duty of the u-phase voltage v _u ,
The pulse interval of the rectangular pulse included in the u-phase voltage v _u becomes small. Similarly, the larger the v-phase duty value D _v and the w-phase duty value D _w , the v-phase voltage v _v , respectively.
The pulse interval of the rectangular pulse included in the w-phase voltage v _w becomes smaller.

Therefore, the u-phase duty value D_u, V phase de
Utility value D_v, And w-phase duty value D_wIs the maximum
Value D_MAXThat the u-phase voltage is detected
v_u, V-phase voltage v_v, W-phase voltage v_wPredetermined pulse interval
The minimum value t of_d ^MINThat it has reached
Value. The switching device 29 has a u-phase voltage v_u, V-phase voltage
v _v, W-phase voltage v_wHas a predetermined minimum value t_d
^MINControl of the inverter 2 by detecting that the
Switch from asynchronous PWM control to synchronous 1-pulse control
It will be.

Thus, the u-phase voltage v_u, V-phase voltage
v_v, W-phase voltage v_wHas a predetermined minimum value t_d
^MINControl of the inverter 2 by detecting that the
Switch from asynchronous PWM control to synchronous 1-pulse control
This contributes to the improvement of the voltage utilization rate. u-phase voltage v_u,
v phase voltage v_v, W-phase voltage v_wMinimum pulse interval of
Value t _d ^MINThat has reached the permanent magnet motor
The amplitude of the pseudo sine wave supplied to the armature 1 is saturated and
Increasing the effective voltage of the pseudo sine wave while maintaining the waveform of the chord wave
It means that it is no longer possible. That is,
With the asynchronous PWM control maintained, the permanent magnet motor 1
The effective voltage supplied to the armature of the
Yes. When this happens, sync 1 pulse immediately
Improve the voltage utilization rate by switching to
be able to.

At this time, in order to increase the effective voltage of the pseudo sine wave, it is possible to use the asynchronous PWM control in the overmodulation mode as in the prior art. However, the synchronous 1-pulse control has a higher voltage utilization rate than the asynchronous PWM control in the overmodulation mode. In the present embodiment, the voltage utilization factor is further improved by switching from the asynchronous PWM control in which the modulation degree is less than 1 to the synchronous 1-pulse control.

When the asynchronous PWM control is switched to the synchronous 1-pulse control, any one of the u-phase duty value D _u , the v-phase duty value D _v , and the w-phase duty value D _w becomes the maximum value D _MAX for a predetermined period. When maintained,
That is, when the pulse intervals of the u-phase voltage v _u , the v-phase voltage v _v , and the w-phase voltage v _w are maintained at the minimum value t _d ^MIN for a predetermined period, the asynchronous PWM control is switched to the synchronous 1-pulse control. Is preferably performed. This prevents erroneous switching to synchronous 1-pulse control due to noise or the like. Switch 29, u-phase duty value _D u, v-phase duty value _{D v,} and the period during which any of the w-phase duty value _{D w} is maintained at the maximum value _{D M AX,} a clock signal input to the MPU12 C
It is detected by the number of LK clocks.

Further, the minimum value t _d ^MIN of the pulse interval is
Switching transistor 8 included in the inverter 2
u, 8v, 8w, 9u, 9v, 9w are determined according to the switching time, and the switching transistors 8u, 8
It is preferable to be set to twice the switching time of v, 8w, 9u, 9v, 9w. As a result, the maximum voltage utilization rate allowed by the switching capability of the switching transistors 8u, 8v, 8w, 9u, 9v, 9w can be achieved.

When the asynchronous PWM control is switched to the synchronous 1-pulse control, the synchronous 1-pulse control calculator 28
It is necessary to determine the voltage vector of the three-phase voltage supplied to the armature of the permanent magnet motor 1 immediately after switching to the synchronous 1-pulse control. This voltage vector is preferably defined as follows.

The synchronous 1-pulse control calculator 28 is operated by the asynchronous P
Before switching from WM control to synchronous 1-pulse control
The voltage of the output wave supplied to the permanent magnet motor 1
The last voltage of the tor other than (000) and (111)
What is the vector (hereinafter called “final voltage vector”)?
To determine if. Where the voltage vector (x₁x _Two
x_Three) Is the u-phase power line 4u, the v-phase power line 4v, and the w-phase
The potential of the power supply line 4w is the power supply potential V_dc, At 0 potential
If there is, x₁= 0, u-phase power supply line 4u
Is zero potential, x₁= 1, the u-phase power supply line 4u
It is the source potential. Similarly, x_Two= 0, v-phase power line 4
v is 0 potential, x_Two= 1, the v-phase power line 4v is
Power supply potential, x_Three= 0, the w-phase power supply line 4w is 0
Potential and x_Three= 1, the w-phase power supply line 4w has a power supply potential
Is. For example, from asynchronous PWM control to synchronous 1-pulse control
Just before switching to control, u-phase power supply line 4u, v-phase power supply
Line 4v is power supply potential V_dcAnd the w-phase power line 4w is 0
If it is a potential, the final voltage vector is (110)
Is. Also, from asynchronous PWM control to synchronous 1 pulse control
The voltage vector when switched to is (000)
And when the previous voltage vector was (110)
Has a final voltage vector of (110). Sync 1 Pal
The control unit 28 controls the final voltage vector and only one phase.
A switching voltage vector having different values is determined, and the u-phase power supply line 4u,
The potentials of the v-phase power line 4v and the w-phase power line 4w are switched off.
Asynchronous, as specified by the replacement voltage vector
Immediately after switching from PWM control to synchronous 1-pulse control
Switching signal S_Two ^pu, S_Two ^nu, S_Two ^pv, S
_Two ^nv, S_Two ^pw, And S_Two ^nwTo generate. like this
Then, switch from asynchronous PWM control to synchronous 1-pulse control.
The rotation of the permanent magnet motor 1 is smoothed by changing
The control switching is performed while the control is turned on.

On the other hand, from synchronous 1-pulse control to asynchronous PWM
Switching to control is performed in response to the rotation speed ω _m of the permanent magnet motor 1. While the inverter 2 is controlled by the synchronous 1-pulse control, the switching device 29 keeps the permanent magnet motor 1
The rotation speed ω _{m of} is monitored. Rotational speed ω of the permanent magnet motor 1
_{When m} decreases to a predetermined number of revolutions, the switching device 29
Switches the switching command S from the synchronous 1-pulse switching command S ₂ to the asynchronous PWM switching command S ₁ . As a result, the control of the inverter 2 is switched from the synchronous 1-pulse control to the asynchronous PWM control.

In the motor control system of this embodiment, as shown in FIG. 1, the battery 3 is used as the voltage source for supplying the DC voltage to the inverter 2, but another DC power source is used. It can also be used.
However, since the electric motor control system of the present embodiment can increase the voltage utilization rate, it is particularly useful in an electric motor control system in which the battery 3 having a restriction on the maximum voltage that can be supplied is used for supplying a DC voltage. is there.

Further, the above-mentioned electric motor control system is shown in FIG.
It is also applicable to the control of the induction motor 1 ', as shown in FIG. In this case, the encoder 11 that measures the position θ of the rotor uses the rotation frequency ω of the rotor of the induction motor 1 ′.
_Replaced by an encoder 11 'that measures _m , and further MP
The behavior of U12 is changed. Operations corresponding to the slip frequency calculator 33, the adder 34, and the rotating magnetic flux position calculator 35 are added to the operation of the MPU 12.

The slip frequency calculator 33 determines the d-axis current i _d
And the q-axis current command value i _q ^* , the slip frequency ω _s is calculated. The slip frequency ω _s is the following formula:

[Equation 3] It is calculated by equation (4). Here, R ₂ is the resistance of the secondary winding (rotor winding) of the induction motor 1 ′, and L ₂ is the inductance of the secondary winding of the induction motor 1 ′. The slip frequency calculator 33 adds the calculated slip frequency ω _s to the adder 34
Supply to.

[0063] The adder 34 supplies the sum ω _m + ω _s of the rotational frequency omega _m and slip frequency omega _s in the rotating magnetic field position calculator 35.

The rotating magnetic field position calculator 35 calculates the sum ω _m + ω _s
Is integrated to calculate the position θ ′ of the rotating magnetic field of the induction motor 1 ′. That is, the rotating magnetic field position calculator 35 calculates the position θ ′ of the rotating magnetic field from θ ′ = ∫C (ω _m + ω _s ) dt (Equation (5)). The rotating magnetic field position calculator 35 calculates the calculated position θ ′ of the rotating magnetic field into three phases-2.
It is supplied to the phase converter 21 and the two-phase to three-phase converter 26. Three
The phase-to-two-phase converter 21 controls the position θ ′ of the supplied rotating magnetic field.
Are used to convert the u-phase current i _u , the v-phase current i _v , and the w-phase current i _w into the d-axis current i _d and the q-axis current i _q .
The 2-phase to 3-phase converter 26 uses the position θ ′ of the supplied rotating magnetic field to convert the d-axis voltage command value v _d ^* and the q-axis voltage command value v _q ^* to the u-phase voltage command value v _u. ^* , V-phase voltage command value v _v ^* , and w-phase voltage command value v _w ^* .

[0065]

According to the present invention, an inverter control technique having a higher voltage utilization rate is provided.

The present invention also provides an inverter control technique suitable for an electric motor control system using a battery as a DC power source.

[Brief description of drawings]

FIG. 1 shows an embodiment of an electric motor control system according to the present invention.

FIG. 2 is a block diagram showing an operation of the MPU 12.

FIG. 3 shows switching signals S ₁ ^pu and S ₁ ^nu.
The generation method of is shown.

FIG. 4 shows a modification of the embodiment of the electric motor control system according to the present invention.

[Explanation of symbols]

1: Permanent magnet motor 1 ': Induction motor 2: Inverter 3: Battery 4u: u-phase power line 4v: v-phase power line 4w: w-phase power line 5u, 5v, 5w: Current detector 6, 7: Power line 8u , 8v, 8w, 9u, 9v, 9w: Switching transistor 10: Smoothing capacitor 11, 11 ': Encoder 12: MPU 21: Three-phase to two-phase converter 22, 24: Subtractor 23, 25: PI controller 24 : Subtractor 27: Asynchronous PWM calculator 28: Synchronous 1-pulse control calculator 29: Switcher 30u: u-phase duty register 30v: v-phase duty register 30w: w-phase duty register 31u: u-phase upper timer 31v: v-phase upper Timer 31w: w phase upper timer 32u: u phase lower timer 32v: v phase lower timer 32w: w phase lower tie Over 33: slip frequency calculator 34: adder 35: the rotating magnetic field position calculator

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H02P 7/63 302 H02P 5/408 C 21/00 H 6/02 371W F term (reference) 5H007 BB06 CA01 CB02 CB04 CB05 CC03 CC23 DA03 DA06 DB07 DC02 DC04 EA02 EA10 5H560 BB04 BB12 DA07 DB07 DC01 DC12 EB01 EC02 RR05 SS02 TT01 TT02 TT11 UA02 XA02 XA12 XA13 5H576 CC04 DD02 DD04 DD07 EE01 EE12 JJ12 JJ02 JJ04 JJ14 HA02 JJ04 HA02 EE14 EJ02 EE14 EJ02 EE14 EJ14 EJ02 EE14 EJ02 EE14 JJ14

Claims (9)

[Claims] 1. A three-phase electric motor, an inverter for supplying a three-phase voltage to the three-phase electric motor, and a control device, the control device including the following steps: (a) asynchronous PWM (Pulse width modulation) control. Generating a three-phase first output wave composed of rectangular pulses and outputting the three-phase voltage as the three-phase voltage (b) in response to the pulse interval of the rectangular pulses,
A motor control system for controlling the inverter so that the inverter executes a step of switching a phase voltage to a second output wave of three phases including a single rectangular pulse per half cycle. 2. The electric motor control system according to claim 1, wherein the modulation rate of the asynchronous PWM control is set to be less than 1. 3. The electric motor control system according to claim 1, wherein the control device causes the inverter to execute the step (b) when the pulse interval decreases to a predetermined value. Control system. 4. The electric motor control system according to claim 1, wherein the controller causes the inverter to execute the step (b) when the pulse interval is maintained at a predetermined value for a predetermined time. Motor control system. 5. The electric motor control system according to claim 3, wherein the predetermined value is set according to a switching speed of a switching element included in the inverter. 6. The electric motor control system according to claim 1, wherein the control device includes: (c) in the asynchronous PWM control, among the voltage vectors of the first output wave supplied to the three-phase electric motor, the ( b) (000), (111) before step is performed
A final voltage vector that is a final voltage vector other than the above, and (d) performing a step of defining a switching voltage vector having a different value of only one phase from the final voltage vector, and (e) the above A motor control system that causes the inverter to perform the step of outputting the second output wave corresponding to a switching voltage vector. 7. An inverter for supplying a three-phase voltage to a three-phase electric motor, and a controller, wherein the controller comprises the following steps: (a) A rectangular pulse by asynchronous PWM (Pulse width modulation) control. Generating the generated three-phase first output wave and outputting it as the three-phase voltage (b) in response to the pulse interval of the rectangular pulse,
A motor controller that controls the inverter so that the inverter executes the step of switching the phase voltage to a three-phase second output wave including a single rectangular pulse per half cycle. 8. A motor driving inverter control method for supplying a three-phase voltage to a three-phase motor by an inverter, comprising: (a) three-phase rectangular pulse by asynchronous PWM (Pulse width modulation) control. Generating a first output wave of the three-phase voltage and outputting it as the three-phase voltage, (b) in response to the pulse interval of the rectangular pulse,
And a step of switching the phase voltage to a three-phase second output wave including a single rectangular pulse per half cycle. 9. A computer program for controlling an inverter for supplying a three-phase voltage to a three-phase electric motor, comprising: (a) an asynchronous PWM (Pulse width)
modulation) control to generate a three-phase first output wave composed of a rectangular pulse and output the three-phase voltage, (b) in response to the pulse interval of the rectangular pulse, the inverter A computer program for causing a computer to execute a step of switching the three-phase voltage to a second output wave of three phases configured to include a single rectangular pulse per cycle.