JP2001128483A - Drive control method and device of dc commutatorless motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow a motor drive current to be subjected to sinusoidal control by using a rotary position detector, such as an inexpensive Hall IC without using rotary encoders, and at the same time, to improve traveling feeling and performance by estimating the error of the estimated value of the angle of rotation in acceleration and deceleration. SOLUTION: In this drive control method of a DC commutatorless motor, where the rotational speed of a rotor is detected based on change in a position signal which is outputted for each specific angle of rotation of a rotor by a rotor position detector being provided for each phase of an armature coil, the angle of rotation of the rotor is estimated according to the position signal and the rotational speed, and an armature coil current is subjected to sinusoidal control based on the estimated value of the angle of rotation, the estimated value of the angle of rotation is increased (or decreased), when the rotor is accelerated (or decelerated).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention detects a rotor position discontinuously without using a rotary encoder or the like.
The present invention relates to a drive control method and apparatus for a DC non-commutator motor that estimates a rotation angle from a rotation speed and uses the estimated value to control a sine wave of an armature coil current.

[0002]

2. Description of the Related Art In a DC non-commutator motor (brushless DC motor), the rotational position of a rotor is detected, and the coils of an armature (stator) are excited in accordance with the rotational position. The rotational position of the rotor can be detected by using a rotary encoder. However, high resolution rotary encoders are very expensive.

Therefore, the following method for detecting a rotational position without using a rotary encoder has been proposed.
The first method is to use a digital output Hall IC whose output changes on and off according to a change in the rotational position of the rotor. In this case, the armature coil current is controlled in a rectangular wave shape based on the rectangular wave position data.

A second method is to use a Hall element whose output changes continuously (linearly) as the rotational position of the rotor changes. In this case, the armature coil current is continuously controlled by the position data of the Hall IC that changes in an analog manner. The third method detects a back electromotive voltage (induced voltage) induced in the armature coil with the rotation of the rotor, detects the magnetic pole position (rotated position) of the rotor from a change in the voltage, and In this method, voltage values are used as position data.

[0005]

The first method includes:
There is an advantage that the Hall IC can be obtained at low cost, but there is a problem that the resolution of detecting the rotational position is poor (for example, every 60 electrical degrees). Therefore, since the armature coil current changes stepwise, especially when used for driving a vehicle, the motor driving force does not change smoothly when starting or climbing at a low speed, and the torque fluctuation of the motor driving force is rugged. It is transmitted to the car body as a feeling, and the driving feeling is worsened.

The second method has an advantage that the absolute position of the rotor can be detected, but has a problem that the Hall element used here is more expensive than the Hall IC. In the third method, no inconvenience occurs in the middle / high-speed rotation speed range. However, when the vehicle starts moving, no induced voltage is generated and the rotation position cannot be detected until a predetermined rotation speed is reached. Therefore, there is a problem that this motor cannot be used for driving a vehicle.

Therefore, instead of the first to third methods, a method of solving the problem of poor resolution in the first method (hereinafter referred to as a fourth method) is considered. That is, a method of estimating a fine rotation position using the rotation speed between the positions detected by the Hall IC.

According to the fourth method, the armature coil current can be sine-wave controlled from the estimated value of the rotation angle between the detected positions of the Hall IC. Therefore, low-speed rotation can be performed smoothly using a low-cost Hall IC, and when this motor is used in a vehicle, driving feeling is improved.

However, in the fourth method, in a transient state such as when the rotor is accelerated or decelerated, the difference between the estimated value of the rotation angle and the actual rotation angle becomes large, so that smooth operation cannot be performed.
Especially in small vehicles, rapid acceleration and deceleration are performed.
The error of the estimated value increases. For this reason, there has been a problem that the power factor is deteriorated, the power performance is deteriorated, and the driving feeling is deteriorated.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and it is an object of the present invention to control a motor drive current by using a rotational position detector such as an inexpensive Hall IC without using a rotary encoder. It is an object of the present invention to provide a drive control method of a DC non-commutator motor, which is capable of improving running feeling and improving performance by predicting an error of an estimated value of a rotation angle during acceleration and deceleration. . Another object of the present invention is to provide an apparatus which can be used directly for performing the method.

[0011]

According to the present invention, a first object is to rotate a rotor based on a change in a position signal output for each predetermined rotation angle of a rotor by a rotor position detector provided for each phase of an armature coil. The motor detects the rotational speed of the armature, estimates the rotational angle of the rotor from the position signal and the rotational speed, and drives the DC non-rectifier motor that controls the sine wave of the armature coil current based on the estimated value of the rotational angle. A drive control method for a DC non-commutator motor, wherein the control method corrects the estimated value of the rotation angle to increase (or decrease) at the time of acceleration (or at the time of deceleration) of the rotor; Is achieved by

In this case, the rotation angle is estimated for each calculation processing time (q) that is sufficiently shorter than the time interval (t) at which the position signal changes, and (1 + n) when accelerating to a continuous deviation Δθ of the estimated value θ. ) (N is a positive constant) to determine the deviation Δθ during acceleration, and by integrating the deviation Δθ, the estimated value θ can be determined. Similarly, at the time of deceleration, the estimated value θ can be obtained by multiplying the deviation Δθ by m (m is a constant satisfying 0 <m <1). Instead of multiplying the coefficient (1 + n) or m to the deviation Δθ, a certain number may be added or subtracted.

A second object is to detect the rotation speed of the rotor based on a change in a position signal output for each predetermined rotation angle of the rotor by a rotor position detector provided for each phase of the armature coil. A drive control device for a DC non-commutator motor that estimates a rotation angle of a rotor from the position signal and the rotation speed, and controls a sine wave of the armature coil current based on the estimated value of the rotation angle; The present invention is achieved by a drive control device for a DC non-commutator motor, comprising: a correction unit that corrects the estimated value of the rotation angle so as to increase (or decrease) the estimated value of the rotation angle when the child is accelerating (or decelerating).

[0014]

FIG. 1 is a diagram showing a power transmission system when the present invention is applied to an electric assisted bicycle, FIG. 2 is a diagram illustrating a motor control device, FIG. 3 is a diagram illustrating a configuration of an inverter, and FIG.
FIG. 5 is a block diagram illustrating the configuration of the control device, FIG. 5 is an operation flowchart at the time of acceleration, and FIG. 6 is an operation explanatory diagram.

In FIG. 1, the pedaling force of the driver is transmitted to a resultant shaft 3 via a crankshaft 1 driven by a pedal (not shown) and a one-way clutch 2. The output of the three-phase DC non-commutator motor 4 is transmitted to the resultant shaft 3 via the speed reducer 5 and the one-way clutch 6. The rotation of the resultant shaft 3 is transmitted to a rear wheel 8 as a driving wheel via a freewheel clutch 7.

The manual drive system is a transmission system from the crankshaft 1 to the rear wheel 8, and the electric drive system is a transmission system from the motor 4 to the rear wheel 8. The driving force of human-driven system that is pedaling force T _P
Is detected by the pedaling force sensor 9 from between the one-way clutch 2 and the resultant shaft 3.

Reference numeral 10 denotes a control device for the motor 4. The control device 10 and the depression force T _P depression force sensor 9 detects, controls the output torque T _M That the motor current of the motor 4 based on the vehicle speed V _SP of the vehicle speed sensor 11 detects. Reference numeral 12 denotes a DC power supply such as a battery. Here, the vehicle speed sensor 11
It can be formed by a sensor (not shown) for detecting the rotation speed of the rear wheel 8, the front wheel (not shown), the rotating portion of the drive system, and the like. The vehicle speed sensor 11 may be configured by a circuit that detects a rotation speed based on a back electromotive voltage induced in an armature coil of the motor 4 or calculated using a rotation speed v and a reduction ratio detected by an estimation unit 17 described later. Can also be obtained by

As shown in FIGS. 2 and 4, the control device 10 includes an inverter unit 13, a gate driving unit 14, and an arithmetic processing unit 15.
And The inverter unit 13 is configured by a known three-phase bridge circuit as shown in FIG. That is, MOS-F
Each set in which two switching elements Q _{1 to} Q ₆ such as ET and bipolar transistor are connected in series is connected in parallel to the power supply 12, while each set of switching elements Q ₁ and Q ₂ , Q ₃
And Q ₄ , and between Q ₅ and Q ₆ are connected to the armature coils of each phase of the motor 4. The gate driver 14 sends a gate signal to selectively turn on and off the switching element Q ₁ to Q ₆ to the gates of the switching elements Q ₁ ~Q _6, P
WM (Pulse Width Modulation) control is performed.

The arithmetic processing unit 15 is configured as shown in FIG. 4 and includes a microcomputer (MicroProcessor Unit, MP).
U) and various memories. In this embodiment, the magnitudes of the armature currents i _U , i _V , i _W supplied to the armature (stator) ST are determined based on the rotation angle θ and the rotation speed v of the rotor R of the motor 4. A current command value i ^* indicating the phase is obtained by calculation. That is, vector control is performed.

The rotation angle θ and the speed v of the rotor R are determined by the armature S
T three phases for Hall IC16 as the rotational position detector respectively (16U, 16V, 16W) is output position signal _{P (P U, P V,} P W) based on the estimates by the estimation unit 17 . That is, the Hall IC 16 is provided every 60 ° in electrical angle, and each time the rotor R rotates 60 °, one of the position signals P changes on / off.

The estimating unit 17 detects from this change in the position signal P that the rotor R has turned an electrical angle of 60 °, and determines the rotation speed v from the time interval in which the position signal P is kept constant without change. To detect. Further, the position signal P is calculated using the rotational speed v.
The rotation angle θ within the time interval in which does not change is calculated. As a result, the rotation angle θ during the rotation of the rotor R can be obtained with high resolution.

The estimated values of the rotation angle θ and the rotation speed v obtained by the estimating unit 17 are input to a correcting unit 18 where the estimated values of the rotating angle θ are corrected during acceleration. That is, correction is performed so as to increase the rotation angle θ during acceleration. This correction can be performed, for example, as follows.

In FIG. 6, the position signals P of the U, V, and W phases change with a phase difference of 60 ° in electrical angle.
The correction unit 18 monitors a time t of 60 ° (electrical angle) at which the position signal P changes, and determines acceleration / deceleration from the change of the time t. Here, the acceleration is determined from the decrease in the time t. In FIG. 6, the acceleration is indicated by II, and the constant speed is indicated by I.

Now, the time required for one rotation of the rotor is τ (se
c), the rotation speed N (RPM) is N = 60 / τ
It is. Therefore, if the number of pole pairs of the rotor is p (here, p = 4) and the time required for rotation at an electrical angle of 60 ° (= 360 ° / 6) is t (sec), N = 60 / (6pt)
= 10 / (pt).

Using this rotation speed N (RPM), the angle deviation Δθ that changes every calculation processing time q is obtained as follows. Here, the arithmetic processing time q is sufficiently shorter than the time interval t of the electrical angle of 60 °. For example, MPU is 16KH _Z
(That is, every 62.5 μsec), the electric angle is calculated as q = 62.5 μsec. The rotation angle that changes during the time q, that is, the deviation Δθ, is obtained as follows.

[0026]

Δθ = (electrical angle progressing in one second) × q × p = (N / 60) · 360 ° · q · p = N · 0.0015 (a)

Therefore, when N = 3000 RPM, Δθ =
It becomes 4.5 °. That is, the rotation angle θ changes by 4.5 ° during q = 62.5 μsec. The rotation angle θ can be determined by continuously adding Δθ. That is, θ = ΣΔθ. In this embodiment, the deviation Δθ obtained by the equation (a) is corrected so as to increase during acceleration. That is, during acceleration, Δθ is replaced with Δθ · (1 + n). Here, n is a positive constant and can be determined by experiment.

The estimated values of the rotation angle θ and the rotation speed v obtained by the correction unit 18 in this manner are input to the current calculation unit 19. The current calculator 19 calculates the magnitude and phase of the current command value i ^* based on the torque target value T _M obtained by the target torque calculator 20 and the rotation angle θ and the rotation speed v.

The target torque calculator 20 calculates the vehicle speed V_SPAnd treading power
T_PMotor torque T based on_MAsk for.
For example, the vehicle speed V_SPMotor assist rate η
(= T_M/ T_P) According to the gradually decreasing auxiliary characteristics
Luc T_MTarget value of T_M= T _P・ Calculate as η. This model
In data 4, torque T_MIs the actual armature current i_R(I_U,
i_V, I_W). The current calculator 19 calculates the target torque
Value T_MArmature current i required to generate_Rof
The magnitude and phase are obtained by vector calculation, and the current command value is calculated.
i^*Output as

The current command value i ^* is actually U,
It is output separately for each phase of V and W. That is, the current calculation unit 19 outputs the current command value i ^{* in} which the phases are shifted from each other by an electrical angle of 120 ° using the sine wave pattern data stored in the memory 21. The current command value i ^* of each phase is a sine wave whose amplitude changes according to the magnitude of the target torque value T _M , and the amplitude and phase are calculated based on the rotation angle θ, the rotation speed v, the inertia of the rotating part, and the like. It is a thing.

This current command value i^*Is a subtractor 22
Actual current value i of child ST_RDifference (i ^*−i_R) For each phase
And are required separately. This current value i_RIs the armature ST
Current of the UV phase winding (i_U, I_V) To Hall CT (Curren
t Transformer, CT_U, CT_V)
Then, the W-phase current can be obtained by calculation. This difference
(I^*−i_R) Is the armature current error signal, and the current control unit
23. In the current control unit 23, the inverter 13
A gate drive signal for driving the gate of the
It is sent to the moving part 14. As a result, the motor 4 reaches the target torque value.
T_MAnd the motor output T_MAnd pedaling force T_PAnd by
Bicycles can run.

The above operation is summarized as shown in FIG. First target torque calculating section 20 is pedaling force T _P and the vehicle speed V _SP
Is read (step S100), a motor assist ratio η corresponding to the vehicle speed V _SP is determined (step S102), and a torque T _M required for the motor is determined by T _M = T _P · η (step S104). On the other hand, in the correction unit 18, the rotation angle θ output by the estimation unit 17 is output in parallel with the calculation by the target torque calculation unit 20.
Then, it is determined whether or not the vehicle is accelerating based on the estimated value of the rotation speed V (step S106).

If the vehicle is accelerating, the deviation is corrected by adding (1 + n) to the deviation Δθ shown in the equation (a) (step S108). Unless the vehicle is accelerating, the deviation Δθ is not corrected. The correction unit 18 obtains the rotation angle θ = ΣΔθ by adding the consecutive deviations Δθ (step S1).
12). The corrected rotation angle θ is input to the current calculation unit 19, where the current command value i ^* is calculated while reading the sine wave pattern based on the rotation angle θ from the memory 21 (step S114). The current command value i is calculated by the subtractor 22.
The difference (i ^* −i _R ) between ^* and the actual current value i _R is obtained, and the current control unit 23 performs PWM control on the inverter unit 13 via the gate drive unit 14 so as to set the current error signal to 0. (Step S116).

In the above embodiment, the deviation .DELTA..theta.
Is increased so that the deviation Δθ is reduced at the time of deceleration. Also included is a correction that increases the deviation Δθ during acceleration and decreases the deviation Δθ during deceleration.

[0035]

According to the first aspect of the present invention, as described above, the correction is made so as to increase the estimated value of the rotation angle θ during acceleration, or the correction is made so as to decrease the estimated value of the rotation angle during deceleration. It is possible to improve the running feeling by smoothing the rotation change at the time of deceleration or deceleration. In addition, it is possible to prevent the power factor from deteriorating and the performance from lowering. According to a fourth aspect of the present invention, there is provided an apparatus which can be used directly for performing the method.

[Brief description of the drawings]

FIG. 1 is a diagram showing a power transmission system applied to an electric assist bicycle according to the present invention.

FIG. 2 is an explanatory diagram of a motor control device.

FIG. 3 shows an inverter.

FIG. 4 is a diagram showing a configuration of a control device.

FIG. 5 is an operation flowchart at the time of acceleration.

FIG. 6 is an operation explanatory diagram.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Crankshaft 4 Three-phase DC non-commutator motor 8 Rear wheel (drive wheel) 10 Controller 13 Inverter part 14 Gate drive part 15 Operation processing part 16 Hall IC (rotor position detector) 17 Estimation part 18 Correction part 19 Current calculation unit 20 target torque calculating section 21 sinusoidal pattern data memory _{i R (i U, i V} , i W) armature current _{P (P U, P V,} P W) deviation of the position signal θ rotation angle Δθ rotation angle

Claims (4)

[Claims] 1. A rotor position detector provided for each phase of an armature coil detects a rotational speed of the rotor based on a change in a position signal output at each predetermined rotation angle of the rotor, and detects the rotational speed of the rotor. A drive control method for a DC non-commutator motor that estimates a rotation angle of a rotor from the rotation speed and a rotation speed based on the estimated value of the rotation angle, and controls a sine wave of the armature coil current. A drive control method for a DC non-commutator motor, wherein the estimated value of the rotation angle is corrected so as to increase (or decrease) during (or during deceleration). 2. A rotation angle θ is estimated for each calculation processing time sufficiently shorter than a time interval at which the position signal changes, and a constant (1 + n) is used as a deviation Δθ of the continuous rotation angle θ during acceleration.
The drive control method for a direct current commutator motor according to claim 1, wherein a deviation Δθ during acceleration is obtained by integrating (where n is a positive constant), and a rotation angle θ is obtained by integrating the deviation Δθ. 3. A rotation angle θ is estimated for each operation processing time sufficiently shorter than a time interval at which the position signal changes, and a constant m (where 0
2. The drive control method for a direct current commutator motor according to claim 1, wherein a deviation Δθ during deceleration is calculated by calculating <m <1), and a rotation angle θ is calculated by integrating the deviation Δθ. 4. A rotor position detector provided for each phase of an armature coil detects a rotation speed of the rotor based on a change in a position signal output for each predetermined rotation angle of the rotor, and detects the rotation speed of the rotor. And a rotational speed of the rotor is estimated from the rotational speed, and based on the estimated value of the rotational angle, a drive control device for a DC non-commutator motor that performs sinusoidal control of the armature coil current. A drive control device for a DC non-commutator motor, comprising: a correction unit that corrects the estimated value of the rotation angle to increase (or decrease) during (or during deceleration).