The present invention relates to a motor control apparatus
that calculates duty command values of respective phases for
controlling currents of a motor by means of a control calculation,
forms a pulse width modulation (PWM)-signals in correspondence
to the duty command values of the respective phases, and drives
by applying command currents (voltages) from the inverter to the
motor with a PWM control and further to an electric power steering
apparatus by means of the motor control apparatus to apply an assist
force by the motor to a steering system of a vehicle.
Especially, the present invention relates to a compact,
cheap and low noisy motor control apparatus that provides a single
current detecting circuit (1-shunt type current detecting circuit)
at a power source input side or a power source output side (ground
side) of the inverter and PWM-controls, does not use a motor angle
signal detected by a rotation sensor at a timing of a duty pattern
switching and uses a motor angle estimation signal which is
estimated from plural motor angles (stored values) just before
the timing, thereby to remove noises and prevent an influence of
variations of the motor angle, and further relates to the electric
3
power steering apparatus using the same.
Background Art
An electric power steering apparatus which provides a
steering mechanism of a vehicle with a steering assist torque (an
assist torque) by means of a rotational torque of a motor, applies
a driving force of the motor as the assist torque to a steering
shaft or a rack shaft by means of a transmission mechanism such
as gears or a belt through a reduction mechanism. In order to
accurately generate the steering assist torque, such a conventional
electric power steering apparatus (EPS) performs a feedback control
of a motor current. The feedback control adjusts a voltage supplied
to the motor so that a difference between a steering assist command
value (a current command value) and a detected motor current value
becomes small, and the adjustment of the voltage applied to the
motor is generally performed by an adjustment of duty command values
of a PWM control.
A general configuration of a conventional electric power
steering apparatus will be described with reference to FIG.1. As
shown in FIG.1, a column shaft (a steering shaft, a handle shaft)
2 connected to a steering wheel (a steering handle) 1, is connected
to steered wheels 8L and 8R through reduction gears 3, universal
joints 4a and 4b, a rack and pinion mechanism 5, and tie rods 6a
and 6b, further via hub units 7a and 7b. Further, the column shaft
2 is provided with a torque sensor 10 for detecting a steering
4
torque of the steering wheel 1, and a motor 20 for assisting the
steering force of the steering wheel 1 is connected to the column
shaft 2 through the reduction gears 3. Electric power is supplied
to a control unit (ECU) 100 for controlling the electric power
steering apparatus from a battery 13, and an ignition key signal
is inputted into the control unit 100 through an ignition key 11.
The control unit 100 calculates a current command value of an assist
(steering assist) command based on a steering torque Tr detected
by the torque sensor 10 and a vehicle speed Vel detected by a vehicle
speed sensor 12, and controls a current supplied to the motor 20
based on a voltage control value E obtained by performing
compensation and so on with respect to the current command value.
Moreover, it is also possible to receive the vehicle speed Vel
from a controller area network (CAN) and so on.
The control unit 100 mainly comprises a CPU (or an MPU
or an MCU), and general functions performed by programs within
the CPU are shown in FIG.2.
Functions and operations of the control unit 100 will
be described with reference to FIG.2. As shown in FIG.2, the
steering torque Tr detected by the torque sensor 10 and the vehicle
speed Vel from the vehicle speed sensor 12 are inputted into a
current command value calculating section 101, and a current command
value Iref1 is calculated by means of an assist map and so on.
The calculated current command value Iref1 is inputted into a
maximum output limiting section 102 and an output is limited based
5
on an overheat protection condition or the like in the maximum
output limiting section 102. A current command value Iref2 that
a maximum output is limited, is inputted into a subtracting section
103. Moreover, a torque control section is comprised of the current
command value calculating section 101 and the maximum output
limiting section 102.
The subtracting section 103 calculates a deviation current
Iref3(=Iref2-Im) between the current command value Iref2 and a
motor current Im of the motor 20 that is fed back, the deviation
current Iref3 is controlled by a current control section 104 such
as a PI control (proportional and integral control) or the like.
Then, the controlled voltage control value E is inputted into a
PWM control section 105 and the duty command values are calculated
in synchronous with a saw-tooth carrier signal CS, having a
predetermined frequency, generated in a carrier signal generating
section 107, and in accordance with PWM-signals PS that the duty
command values are calculated, the motor 20 is driven through an
inverter 106. The motor current Im of the motor 20 is detected
by a current detecting circuit 120 within the inverter 106, and
the detected motor current Im is inputted into the subtracting
section 103 to feed back. In a case that a brushless DC motor
as the motor 20 is used for a vector-control, a resolver 21 as
a rotation sensor is connected to the motor 20, and an angular
speed calculating section 22 for calculating an angular speed ω
from a motor angle (rotation angle) θ is provided.
6
A bridge circuit that bridge-connects semiconductor
switching elements (e.g. FETs) and the motor 20 is used in the
inverter 106 that controls the motor current Im by means of the
voltage control value E and drives the motor 20, and the motor
current Im is controlled by performing ON/OFF controls of the
semiconductor switching elements in accordance with the duty
command values of the PWM-signal determined based on the voltage
control value E.
In the case that the motor 20 is a three-phase (U-phase,
V-phase and W-phase) brushless DC motor, details of the PWM control
section 105 and the inverter 106 is a configuration such as shown
in FIG.3. That is, the PWM control section 105 comprises a duty
calculating section 105A that inputs each-phase carrier signal
CS and calculates PWM-duty command values D1 ~ D6 of three phases
(U-phase, V-phase and W-phase) in accordance with a predetermined
expression based on the voltage control value E, and a gate driving
section 105B that drives each gate of FET1 ~ FET6 by the PWM-duty
command values D1 ~ D6 to turn ON/OFF. The inverter 106 comprises
a three-phase bridge having upper/lower arms comprised of a U-phase
upper-stage FET1 and a U-phase lower-stage FET4, upper/lower arms
comprised of a V-phase upper-stage FET2 and a V-phase lower-stage
FET5, and upper/lower arms comprised of a W-phase upper-stage FET3
and a W-phase lower-stage FET6, and drives the motor 20 by being
turned ON/OFF with the PWM-duty command values D1 ~ D6. Further,
electric power is supplied to the inverter 106 from the battery
7
13 through a power-source relay 14.
In such a configuration, although it is necessary to
measure a drive current of the inverter 106 or the motor current
of the motor 20, as one of request items of downsizing, weight
saving and cost-cutting of the control unit 100, a singularity
of the current detecting circuit 120 is proposed. A 1-shunt type
current detecting circuit is known as the singularity of a current
detecting circuit, and for example, the configuration of the 1-shunt
type current detection circuit 120 is shown in FIG.4 (for example,
Japanese Published Unexamined Patent Application No.2009-131064
A). Namely, a shunt resistor R1 is connected between the
lower-stage arm of the FET bridge and the ground (GND), a fall
voltage that is caused by the shunt resistor R1 when a current
flowed in the FET bridge is converted into a current value Ima
by an operational amplifier (a differential amplification circuit)
121 and resistors R2~R4, and further the current value Ima is
A/D-converted at a predetermined timing by an A/D converting section
122 through a filter comprised of a resistor R6 and a capacitor
C1, and then a current value Im that is a digital value is outputted.
Moreover, a voltage “2.5V” being a reference voltage is connected
to a positive input terminal of the operational amplifier 121
through a resistor R5.
In a case that the currents for respective UVW-phases
are detected by the 1-shunt type current detecting circuit, for
example as disclosed in Japanese Published Unexamined Patent
8
Application No.2010-279141 A (Patent Document 1), a method that
a judgement of the maximum duty, the intermediate duty and the
minimum duty is performed and then the judged duties are
sequentially arranged with respect to the shifted carrier period,
is used. That is, the duty setting values for respective phases
are compared, an then the maximum duty, the intermediate duty and
the minimum duty are determined, as a reference being a rising
phase Y of the carrier signal of the intermediate phase, a rising
phase of the carrier signal of the maximum phase is led by a constant
amount as well as a rising phase of the carrier signal of the minimum
phase is lagged by a constant amount. Whereby the PWM-signals
for the respective phases are generated based on the
respective-phase carrier signals of which phases are sifted each
other and the respective-phase duty setting values, and the current
detection is performed in predetermined sections (periods) Tu and
Tw till the respective risings of the PWM-signal of the intermediate
phase and the PWM-signal of the minimum phase so as to be possible
to detect the respective-phase motor currents by the single current
detecting circuit.
The List of Prior Art Documents
Patent Documents
Patent Document 1: Japanese Published Unexamined Patent
Application No.2010-279141 A
Patent Document 2: Japanese Published Unexamined Patent
9
Application No.2006-33903 A
Patent Document 3: Japanese Published Unexamined Patent
Application No.2012-125106 A
Summary of the Invention
Problems to be Solved by the Invention
In a motor control apparatus disclosed in Patent Document
1, when the order of the maximum phase, the intermediate phase
and the minimum phase is the order of U-phase, V-phase and W-phase
due to the rotation angle of the motor, the rising timing of PWM
rises in order of U, V, W as shown in the carrier periods TC1 and
TC2 in FIG.5. However, a next moment, if the size relation of
duties of 3-pahses (U,V,W) is changed into “U-phase is maximum”,
“V-phase is minimum” and “W-phase is intermediate” as shown in
the scope of the carrier period TC3 of FIG.5, the rising timing
of PWM also changes such as from “U-phase” → “V-phase” → “W-phase”
to “U-phase”→ “W-phase”→ “V-phase”. In accordance with this
changing, unintentional duty-variation is temporarily occurred
as shown in FIG.5.
FIG.6 shows the operations thereof, FIG.6(A) does an
appearance that the phase order of the V-phase duty command value
is switched from the intermediate phase to the minimum phase at
a time point t1, and FIG.6(B) does the V-phase current based on
the V-phase duty command value and does a matter that a current
variation (distortion) due to a temporary duty variation which
10
is generated by switching the phases occurs after the time point
t1. Further, FIG.6(C) shows an appearance that the phase order
of the W-phase duty command value is switched from the minimum
phase to the intermediate phase at the time point t1, and FIG.6(D)
does the W-phase current based on the W-phase duty command value
and does a matter that a current variation (distortion) due to
a temporary duty variation which is generated by switching the
phases occurs after the time point t1.
As mentioned above, according to the temporary duty
variation which is generated by switching the PWM-switch timing
of the phase-order of the V-phase and the W-phase at the time point
t1, the variations (distortions) are generated in the V-phase
current and the W-phase current and the motor current varies as
shown in FIG.6(E). In this way, the motor angle detection value
varies as shown in FIG.6(F) and the current command value to be
calculated varies as shown in FIG.6(G). As a result, the duty
command values of UVW-phases vary as shown in FIGs.6(H)~(J), and
therefore the noises occur and the sound and the vibration are
generated.
As stated above, the variation of the phase-order due
to the PWM phase-shift occurs at a moment of the PWM phase-shift,
this variation of the phase-order causes, for example, the
variations (distortions) of the V-phase current and the W-phase
current and further the current distortion causes the variation
of the motor angle. In this connection, the motor angle detection
11
value also varies, the torque control section and the current
control section react in sensitive to the variation of the detection
value, and the variations of the current command value and the
duty command value occur. As a result, a series of a feedback
loop that the V-phase current and the W-phase current more vary
is formed, and an undesirable phenomenon occurring the noisy sound,
the vibration or the like is caused. In the electric power steering
apparatus, the occurring of the sound and the vibration gives an
uncomfortable feeling to the driver and deteriorates the steering
performance.
As a method to lighten the above problems, it is assumed
that the variation is suppressed by performing a constant
filter-processing in view of taking that the varying motor angle
is the noise.
However, as the noise superposed with the rotation (angle)
signal of the rotation sensor such as a resolver, a switching noise
is generally considered. As the reducing method of the switching
noise, it is generally known the method to average the resolver
output signal and to lighten the noise as disclosed in Japanese
Published Unexamined Patent Application No.2006-33903 A (Patent
Document 2). However, if the filter to remove the step-up noise
due to the switching of the PWM-phase as stated above is used,
there is a possibility not to accurately reproduce the resolver
output signal itself, and further there is a problem to become
the steering performance being uncomfortable for the driver in
12
the case of the electric power steering apparatus.
Further, in a control apparatus disclosed in Japanese
Published Unexamined Patent Application No.2012-125106 A (Patent
Document 3), the reducing of the angle detection noise due to the
switching noise is performed with a correction 1 relating to the
rotation speed and a correction 2 relating to the percentage
modulation. However, in the apparatus of Patent document 3, since
whole signal-processing is performed by utilizing the present value
detected by the resolver, there is a problem that the variation
of the resolver output signal itself directly influences to the
apparatus.
Furthermore, Patent Documents 2 and 3 do not disclose
only detection method of the motor current but also consider the
downsizing, the weight saving and the cost-cutting.
The present invention has been developed in view of the
above-described circumstances, and an object of the present
invention is to provide a motor control apparatus that detects
a motor current by using a cheap and compact 1-shunt type current
detecting circuit, does not occur the variations of the current
command value and the duty command values even if the duty variation
due to PWM phase-shift occurs at a moment of the PWM phase-shift,
and further does not occur an uncomfortable phenomenon such as
noisy sound and variation, and to provide an electric power steering
apparatus using the same.
13
Means for Solving the Problems
The present invention relates to a motor control apparatus,
the above-described object of the present invention is achieved
by that: said motor control apparatus that calculates duty command
values of respective phases for controlling currents of a motor
by means of a control calculation, forms PWM-signals in
correspondence to said duty command values of said respective phase,
drives said motor by means of an inverter based on said PWM-signals,
and which is provided a rotation sensor to detect a motor angle
of said motor: wherein a 1-shunt type current detecting circuit
is connected to a power source side or a ground side of said inverter;
and comprising; a comparing section to compare said duty command
values and to determine a size relation of said duty command values;
a timing control section to sequentially enable timings of rising
or falling with respect to said PWM-signals with a predetermined
order based on said size relation; and a motor angle output section
to change an order of said rising in correspondence to a
predetermined algorithm, estimate a motor angle estimation value
based on past values of said rotation sensor at only a timing when
said order of said rising is changed, and output said motor angle
estimation value as said motor angle.
Further, the above-described object of the present
invention is more effectively achieved by that wherein said
predetermined order is an order of a maximum phase, an intermediate
phase, a minimum phase of said duty command values, or wherein
14
said predetermined algorithm is an algorithm that said order of
said rising is also changed at a timing when a relation of a maximum
phase, an intermediate phase and a minimum phase of said respective
phases is changed, or wherein said motor angle output section
comprising a phase-change detecting section to detect a change
of a relation of said maximum phase, said intermediate phase and
said minimum phase, a storing section to store a motor angle of
said rotation sensor with a predetermined period, and a motor angle
estimating section to estimate said motor angle estimation value
from plural past values in said storing section, wherein said motor
angle estimating section estimates said motor angle estimation
value by means of a linear approximation, or wherein said rotation
sensor is a resolver.
It is possible to achieve the electric power steering
apparatus of the above-described object by mounting each of the
above-described motor control apparatuses.
Effects of the Invention
According to the present invention, the motor angle is
estimated with a linear approximation by using plural past values
in the storing section without using of the motor angle (angle
signal) from the rotation sensor (e.g. resolver) at a timing of
the PWM phase-shift, and the estimated motor estimation value is
used for the control. Therefore, it is possible to minimize or
suppress a variation of the motor angle detection value which is
15
one of the feedbacks causing the uncomfortable phenomenon such
as the sound and the vibration.
Accordingly, since the current variation (distortion)
and the angle variation of the motor due to the PWM phase-switching
do not influence to the motor angle detection value, the current
command value becomes a smooth command value wave form that the
variation of the motor angle detection value does not propagate.
As a result, the duty command values are also able to obtain the
smooth duty command value wave form that the above variation does
not influence. Although the duty command values become the smooth
wave form without an influence of the variation of the motor angle
detection value, it is possible to reduce or suppress the occurrence
of the uncomfortable phenomenon for the motor control apparatus
and the electric power steering apparatus.
Brief Description of the Drawings
In the accompanying drawings:
FIG.1 is a configuration diagram illustrating a general
outline of an electric power steering apparatus;
FIG.2 is a block diagram showing a general configuration
example of a control unit;
FIG.3 is a wiring diagram showing a configuration example
of a PWM control section and an inverter;
FIG.4 is a wiring diagram showing a configuration example
of a 1-shunt type current detecting circuit;
16
FIG.5 is a PWM phase diagram showing an operation example
to change the phase-order of the PWM phase of the duty command
value;
FIG.6 is a time chart showing an operation example of
the conventional apparatus;
FIG.7 is a block diagram showing a configuration example
of the present invention;
FIG.8 is a flowchart showing an operation example of the
present invention;
FIG.9 is a flowchart showing an operation example of a
motor angle estimation; and
FIG.10 is a characteristic diagram showing effects of
the present invention.
Mode for Carrying Out the Invention
In a motor control apparatus (electric power steering
apparatus) according to the present invention, a single current
detecting circuit (1-shunt type current detecting circuit) is
provided between an inverter and a power source or between the
inverter and the ground (GND). In order to certainly detect motor
currents of respective UVW-phases by using the 1-shunt type current
detecting circuit, the maximum duty, an intermediate duty and the
minimum duty are determined by comparing the sizes of the duty
command values of the respective phases, as a reference being a
rising phase of the carrier signal of the intermediate phase, a
17
rising phase of the carrier signal of the maximum phase is led
by a constant amount as well as a rising phase of the carrier signal
of the minimum phase is lagged by a constant amount, whereby the
PWM-signals for the respective phases are generated based on the
respective-phase carrier signals of which phases are sifted each
other and the respective-phase duty setting values, and the current
detection is performed in predetermined sections (periods) till
the respective risings of the PWM-signal of the intermediate phase
and the PWM-signal of the minimum phase so as to be possible to
detect the respective-phase motor currents by the single current
detecting circuit.
The present invention detects the switching of the
phase-order of duty patterns, does not use a motor angle (angle
signal) detected by a resolver or the like only at a timing of
a detected phase-order switching and uses a motor angle estimation
signal which is estimated from plural stored values (motor angles)
just before the timing. Thereby, it is possible to prevent or
suppress the variation of the duty command vales due to the variation
of the motor angle detection at the timing of the phase-order
switching without pass through a special filter. The motor angle
detected by the resolver or the like is, as it is, used except
for the timing of the phase-order switching of the duty patterns.
Hereinafter, an embodiment of the present invention will
be described with reference to the accompanying drawings.
FIG.7 shows one example of the embodiment of the present
18
invention in correspondence to FIG.2. As shown in FIG.7, there
are provided a duty setting section 130 to set duty command values
DS corresponding to the duties of PWM-signals of respective phases
based on the voltage control value E from the current control section
104 and the carrier signal CS; a comparing section 131 to compare
the duty command values of respective phases set in the duty setting
section 130, determine the maximum phase, the intermediate phase
and the minimum phase of the duty command values DS and outputs
a size relation signal SR; and a timing control section 132 to
raise timings of rising or falling of the PWM-signals of 3-phases
at a predetermined order, for example, at an order of “the maximum
phase” → “the intermediate phase” → “the minimum phase” of the duty
command values based on the size relation signal SR from the
comparing section 131 and the carrier signal SR and to output the
PWM-signals for driving the motor 20 via the inverter 106.
Further, there are provided a phase-change detecting
section 142 to detect an fact that the order of the rising of the
3-phase PWM-signals outputted from the timing control section 132
is changed and to output a phase-change signal PC at the time when
the change is occurred; a storing section 141 to store the motor
angle θ from the resolver 21 at a predetermined period; and a motor
angle estimating section 140 to read out a stored angle data θm
of the past plural times from the storing section 141 only at a
time when the phase-change signal PC is outputted from the
phase-change detecting section 142, estimate the motor angle by
19
means of the linear approximation and output a motor angle
estimation value θe.
When the phase-change signal PC is not outputted from
the phase-change detecting section 142, the motor angle θ of the
resolver 21 is, as it is, outputted as the motor angle estimation
signal θe. Namely, when the phase-change signal PC is not outputted,
the motor angle estimation signal θe is equal to the motor angle
θ. Further, the current command value Iref2 calculated in the
torque control section 110 is inputted into the subtracting section
103, and the current command value Iref3 which is a deviation between
the current command value Iref2 and the motor current Im detected
by the 1-shunt type current detecting circuit 120, is inputted
into the current control section 104.
Besides, since the output from the resolver 21 is analogue
signal, the storing section 141 actually stores, at a predetermined
sampling period, the digital values A/D-converted by an A/D
converter or the like as the motor angle θ. Further, a motor angle
output section is comprised of the motor angle estimating section
140, the storing section 141 and the phase-change detecting section
142.
In such a configuration, an operation example of the
present invention will be described with reference to a flow chart
of FIG.8. The present flow chart of FIG.8 shows only a part relating
to the present invention.
First, the duty setting section 130 inputs the voltage
20
control value E calculated in the current control section 104 and
the carrier signal CS generated in the carrier signal generating
section 107 (Step S1), and sets the duty command values DS
corresponding to the duty of PWM-signals of respective phases (Step
S2). The duty command values DS set in the duty setting section
130 are inputted into the comparing section 131, the comparing
section 131 compares the duty command values DS of the respective
phases, determine the maximum phase, the intermediate phase and
the minimum phase of the duty command values DS and outputs the
size relation signal SR (Step S3).
The timing control section 132 inputs the size relation
signal SR from the comparing section 131, and raises the timings
of rising (or falling) of the PWM-signals of 3-phases at the
predetermined order (Step S4). The predetermined order is, for
example, an order of “the maximum phase” → “the intermediate phase”
→ “the minimum phase”, or an order of “the minimum phase” → “the
intermediate phase” → “the maximum phase” or the like. The
PWM-signals controlled the timings in the timing control section
132 are outputted (Step S5), and the motor 20 is driven by using
the PWM-signals PS via the inverter 106 (Step S10).
The respective phase motor currents of the motor 20 are
detected by the 1-shunt type detecting circuit 120 as stated above
(Step S11), the detected motor currents Im is fed back to the
subtracting section 103. Further, the motor angle θ is detected
by the resolver 21 (Step S21), and the detected motor angle θ is
21
stored in the storing section 141 at a predetermined sampling period
(Step S13).
On the other hand, the phase-change detecting section
142 detects whether there is a phase-change by changing the order
of the rising based on the PWM-signals or not (Step S14), when
the phase-change is detected, the phase-change detecting section
142 outputs the phase-change signal PC. The phase change signal
PC is inputted into the storing section 141 and the motor angle
estimating section 140, the motor angle estimating section 140
reads out plural past motor angles θm just before input of the
phase-change signal PC and estimates the motor angle θe by means
of the linear approximation based on the plural motor angles θm
(Step S20). The estimated motor estimation value θe is outputted
from the motor angle estimating section 140 (Step S30). When the
phase-change signal PC is not outputted from the phase-change
detecting section 142, the motor angle θ of the resolver 21 is,
as it is, outputted as the motor angle estimation signal θe (=θ).
The flow chart of FIG.9 shows the details of the motor
angle estimation at the Step S20, when the phase-change signal
PC is inputted from the phase-change detecting section 142 (Step
S21), the motor angle estimating section 140 reads out plural past
stored values (motor angles θm) from the storing section 141 (Step
S22). The motor angle estimating section 140 estimates the motor
angle with the known linear approximate calculation by using the
plural past stored values (Step S23), and outputs the estimated
22
motor angle estimation value θe (Step S24).
FIG.10 shows effects of the present invention with
reference to FIG.6. In the present invention, even if the motor
angle θ varies due to the phase-change as shown in FIG10.(E), when
the phase-change occurs as shown in FIGs.10(A) and (C), the motor
angle estimating section 140 estimates the motor angle as shown
in FIG.10 (F) by means of the linear approximation, a logarithmic
approximation and so on from the past values θm of the motor angle
θ based on the phase-change signal PC detected by the phase-change
detecting section 142. Then, the estimated motor angle estimation
value θe is used for the control calculation. Consequently, as
shown in FIGs.10(G)~(J), variations in the current command value
and the duty command values do not occur, and it is possible to
output smooth current command value and the duty command values.
Explanation of Reference Numerals
1 steering handle (steering wheel)
10 torque sensor
12 vehicle speed sensor
13 battery
20 motor
21 resolver
22 angular speed calculating section
100 control unit (ECU)
101 current command value calculating section
23
102 maximum output limiting section
104 current control section
105 PWM control section
105A duty calculating section
105B gate driving section
106 inverter
107 carrier signal generating section
120 1-shunt type current detecting circuit
130 duty setting section
131 comparing section
132 timing control section
140 motor angle estimating section
141 storing section
142 phase-change detecting section

We Claim:
1. A motor control apparatus that calculates duty command
values of respective phases for controlling currents of a motor
by means of a control calculation, forms PWM-signals in
correspondence to said duty command values of said respective phase,
drives said motor by means of an inverter based on said PWM-signals,
and which is provided a rotation sensor to detect a motor angle
of said motor:
wherein a 1-shunt type current detecting circuit is
connected to a power source side or a ground side of said inverter;
and comprising;
a comparing section to compare said duty command values
and to determine a size relation of said duty command values;
a timing control section to sequentially enable timings
of rising or falling with respect to said PWM-signals with a
predetermined order based on said size relation; and
a motor angle output section to change an order of said
rising in correspondence to a predetermined algorithm, estimate
a motor angle estimation value based on past values of said rotation
sensor at only a timing when said order of said rising is changed,
and output said motor angle estimation value as said motor angle.
2. A motor control apparatus according to Claim 1, wherein
said predetermined order is an order of a maximum phase, an
intermediate phase, a minimum phase of said duty command values.
3. A motor control apparatus according to Claim 1 or 2, wherein
said predetermined algorithm is an algorithm that said order of
25
said rising is also changed at a timing when a relation of a maximum
phase, an intermediate phase and a minimum phase of said respective
phases is changed.
4. A motor control apparatus according to any one of Claims
1 to 3, wherein said motor angle output section comprising a
phase-change detecting section to detect a change of a relation
of said maximum phase, said intermediate phase and said minimum
phase, a storing section to store a motor angle of said rotation
sensor with a predetermined period, and a motor angle estimating
section to estimate said motor angle estimation value from plural
past values in said storing section.
5. A motor control apparatus according to Claim 4, wherein
said motor angle estimating section estimates said motor angle
estimation value by means of a linear approximation.
6. A motor control apparatus according to any one of Claims
1 to 5, wherein said rotation sensor is a resolver.
7. An electric power steering apparatus provided with said
motor control apparatus according to any one of Claims 1 to 6.