JP2001128479A - 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 use an inexpensive computer for low-speed processing by eliminating the need for setting high the processing speed of the computer being used to estimate the angle of rotation at high-speed rotation. 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 being outputted for each specific angle of rotation of a rotor by a rotor position detector 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, an armature coil current is subjected to sinusoidal control based on the estimated value of the angle of rotation, when a motor is rotated at low speed, the immediate, previous speed data obtained for each minimum electrical angle, where the position signal is changed is used for estimating the angle of rotation. When the motor is rotated at high speed, the immediate, previous speed data obtained for each specific electrical angle which is larger than the minimum one is used for estimating the angle of rotation.

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, it is necessary to estimate the rotation angle θ for each minimum angle (referred to as a minimum electrical angle) at which the position signal changes in order to smoothly rotate at low speed. The time required for rotation at the minimum electrical angle is sufficiently longer at low speed rotation than the processing time of the computer,
It becomes extremely short at high speed rotation. For this reason, the processing speed of the computer used for estimating the rotation angle must be able to cope with high-speed rotation. Therefore, a computer capable of high-speed processing is required, causing a problem that the computer becomes extremely expensive.

[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. A drive control of a DC non-commutator motor that enables the use of an inexpensive computer for low-speed processing while eliminating the need to increase the processing speed of a computer used for estimating the rotation angle during high-speed rotation. The aim is to provide a method. 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, an object of the present invention is to provide a method for detecting a position of a rotor based on a change in a position signal output by a rotor position detector provided for each phase of an armature coil for each predetermined rotation angle of the rotor. A drive control method for a DC-less commutator motor that detects a rotation speed, estimates a rotation angle of the 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. When the motor rotates at a low speed, the rotation angle is estimated using the immediately preceding speed data obtained for each of the minimum electrical angles at which the position signal changes. A drive control method for a DC non-commutator motor, characterized in that a rotation angle is estimated using the immediately preceding speed data obtained for each angle.

In a three-phase motor, three rotational position detectors output position signals whose phases are shifted by 60 degrees in electrical angle. In this case, at low speeds, speed data detected at every minimum electrical angle of 60 degrees is used. The rotation angle is estimated, and at high speed, the electrical angle is 36.
The rotation angle can be estimated every 0 °. Instead of dividing the rotational speed into two speed ranges of a low speed and a high speed, it is also possible to divide the speed into three or more stages and increase the electrical angle for estimating the rotational angle in order. For example, the rotation angle is estimated for each electrical angle obtained by increasing the multiple of the minimum electrical angle as the rotation speed increases.

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-rectifier 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, When the motor rotates at a low speed, the rotation angle is estimated using the speed data obtained immediately before each of the minimum electrical angles at which the position signal changes. A drive control device for a DC non-commutator motor, comprising: an estimating unit for estimating a rotation angle by using the speed data.

This device can be applied to an electric assisted bicycle in which a human drive system and an electric drive system are provided in parallel, and a current command value of a motor of the electric drive system is determined by the driving force of the human drive system. .

[0015]

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 a diagram illustrating timing of sampling of speed data at the time of acceleration, FIG. 6 is a diagram illustrating a concept of operation of rotation angle estimation, and FIG. 7 is an operation flowchart.

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 unit 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 that the rotor R has turned 60 electrical degrees from the change in the position signal P, and determines the rotation speed v from the time interval in which the position signal P is kept constant without changing. 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.

[0023] The estimation unit 17 performs estimation calculation of the rotation angle θ for each minimum electrical angle until the motor speed v reaches set speed N ₀ (60 °), an electrical angle becomes the set speed N ₀ or 360 The estimation calculation of the rotation angle θ is performed for each ° (2π radians). 5 and 6 illustrate the concept of this operation. FIG. 5 shows the speed data at the sampling timing of every 60 ° (electrical angle) to estimate the rotation angle of the next cycle and the speed data at the sampling timing of 360 ° to determine the rotation angle of the next cycle. The operation at high speed to be estimated is shown.

FIG. 6 shows the time t _L (in the cycle of the immediately preceding electrical angle of 60 ° every electrical angle of 60 ° when the motor rotational speed N (RPM) is lower than the set speed N ₀ , that is, at low speed rotation. The time required to rotate an electrical angle of 60 °,
sec), a rotation speed N (RPM) is determined, and the rotation angle θ of the next cycle is estimated using the rotation speed N. Similarly, in a high-speed region where v ≧ N ₀ , the time t _H (electrical angle of 360 °) obtained in the immediately preceding cycle of electrical angle of 360 °.
Indicates that the rotation speed N is determined from the time required to rotate the rotation speed (sec), and the rotation speed N is estimated using the rotation speed N.

This calculation can be performed, for example, as follows. The time T _H required for the rotor to make one rotation in the time t _H required for rotation of the electrical angle of 360 ° (shown as t (0 → 360) in FIG. 6) is T _H = p · t _H (p Is the number of pole pairs of the rotor, where p = 4). Similarly, the time t _L required for rotation at an electrical angle of 60 ° (in FIG. 6, t (0 →
60), t (60 → 120),...), The time T _L required for the rotor to make one rotation is 360 ° = 6
Since 0 ° × 6, T _L = 6 · p · t _L. Therefore, the rotation speed N _H (RPM) at high speed and the rotation speed N _L at low speed
(RPM) is obtained by the following equation.

[0026]

N _H (RPM) = 60 / T _H = 60 / (p · t _H ) N _L (RPM) = 60 / T _L = 60 / (6p · t _L ) = 1
0 / (p · t _L)

Using the rotation speeds N _H (RPM) and N _L , in the next cycle, the angle deviation Δθ that changes every arithmetic processing time q is obtained as follows. Here, the arithmetic processing time q is sufficiently shorter than the time interval of the electrical angle of 60 °. For example, the MPU is (62.5 μsec ₎ at 16 KHz. The rotation angle that changes during this time q, that is, the deviation Δθ, is obtained as follows.

[0028]

(Equation 2)

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, at the time of high speed, the rotation angle θ in the next cycle (360 ° in electrical angle) is estimated using the speed data obtained for each electrical angle of 360 °, so that sufficient time for calculating the speed data is secured. This eliminates the need to make the MPU expensive and fast.

The rotation angle θ and the rotation speed obtained by the estimation unit 17
The estimated value of the degree v is input to the current calculator 18. This current
The calculating unit 18 calculates the torque target calculated by the target torque calculating unit 19.
Value T _MAnd the rotation angle θ and the rotation speed v,
Flow command value i^*Calculate the magnitude and phase of.

The target torque calculator 19 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 18 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 18 outputs the current command value i ^{* in} which the phases are shifted from each other by 120 ° in electrical angle using the sine wave pattern data stored in the memory 20. 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 21
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
22. In the current control unit 22, 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 operations are summarized as shown in FIG. FIG. 7A shows the main operation, and FIG. 7B shows the rotation angle estimation processing operation according to the present invention. First (A)
The main operation will be described based on FIG. Target torque calculator 1
9 reads the pedaling force T _P and the vehicle speed V _SP (step S10
0), the motor assist ratio η corresponding to the vehicle speed V _SP is obtained (step S102), and the torque T _M required for the motor is calculated as T _M = T _P
· Determined by η (step S104). On the other hand, estimation unit 1
7, the rotation angle θ based on the position signal P output from the Hall IC 16 in parallel with the calculation by the target torque calculation unit 19.
And an estimated value of the rotational speed v are obtained.

The rotation angle θ is input to the current calculator 18, where the current command value i ^* is calculated while reading the sine wave pattern based on the rotation angle θ from the memory 20 (step S106). The current command value i is calculated by the subtractor 21.
The difference (i ^* −i _R ) between ^* and the actual current value i _R is obtained, and the current control unit 22 performs PWM control on the inverter unit 13 via the gate drive unit 14 so that the current error signal becomes zero. (Step S108).

The estimating unit 17 obtains the rotation angle θ in accordance with the subroutine of FIG. That is, the rotation speed v of the motor
Is smaller than the set speed N ₀ (step 150), the rotation speed N _L (RPM) is obtained and stored for each electrical angle of 60 ° (step S152), while the rotation is performed using the speed N _L obtained in the immediately preceding cycle. Calculate the angle θ (Step S1)
54). If V ≧ N ₀ (step S150), the rotation speed N _H (RPM) is obtained for each electrical angle of 360 ° (step S156), while the rotation angle θ is obtained using the speed N _H obtained in the immediately preceding cycle. (Step S158).

The rotation angle θ is sent to the current calculator 18, where a sine value (sin θ) corresponding to the rotation angle θ is calculated using the sine wave data stored in the memory 20 (step S160). The current calculation unit 18 calculates the obtained s
The current command value i ^* is calculated using inθ (step S106).

By estimating the rotation angle of the next cycle using the speed data at every 60 ° on the low speed side, sine wave energization can be performed from a very low speed, and the running feeling can be improved. Further, by obtaining the rotation angle of the next cycle using the speed data for every 360 ° on the high speed side, the processing speed of the microcomputer can sufficiently follow.

[0039]

As described above, according to the present invention, the rotational speed is obtained based on the position signal output at each predetermined angle of the rotor by the rotor position detector provided for each phase of the armature coil, and the position signal and the position signal are obtained. When performing sinusoidal control of the armature current while estimating the rotation angle of the rotor from the rotation speed with high resolution, the rotation angle is estimated using the immediately preceding speed data obtained for each minimum electrical angle at low speeds, while the high-speed At the time of rotation, the rotation angle is estimated using the immediately preceding speed data obtained for each predetermined electrical angle larger than the minimum electrical angle.

Therefore, the motor can be sine-wave controlled without using a rotary encoder or a high-resolution sensor, and smooth operation is possible. Further, the processing speed of the computer does not become too high even at the time of high-speed rotation, and an inexpensive computer having a relatively low processing speed can be used. According to the third aspect of the present invention, there is provided an apparatus directly used for performing the method of the first aspect.

[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 a diagram showing a sampling cycle timing of speed data during acceleration.

FIG. 6 is a conceptual diagram of a rotation angle estimation operation.

FIG. 7 is an operation flowchart.

[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 Current calculation part 19 memory _{i R (i U, i V} , W) for storing a target torque calculating section 20 sine wave data armature current _{P (P U, P V,} P W) position signal θ rotation angle

Continued on the front page F term (reference) 5H115 PG10 PI13 PI29 PU08 PU11 PV09 PV24 QN03 QN06 QN09 RB22 SE03 TB06 TO12 TO30 5H560 AA08 BB04 BB12 DA03 DA19 DC12 EB01 GG04 RR01 SS02 TT11 UA05 XA02 XA04 XA08

Claims (3)

[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. And a rotational speed of the rotor is estimated from the rotational speed, and based on the estimated value of the rotational angle, a sine wave control of the armature coil current is performed. While the rotation angle is estimated using the immediately preceding speed data obtained for each of the minimum electrical angles at which the position signal changes, the immediately preceding speed data obtained for each predetermined electrical angle larger than the minimum electrical angle during high-speed rotation of the motor. A drive control method for a DC non-commutator motor, wherein a rotation angle is estimated by using the method. 2. A position signal output from three rotational position detectors having a three-phase armature coil changes with a phase difference of 60 ° in electrical angle, and at the time of low-speed rotation, the speed data obtained immediately before every 60 ° 2. The drive control method for a DC non-commutator motor according to claim 1, wherein the rotation angle is estimated using the speed data, and at the time of high speed rotation, the rotation angle is estimated using the immediately preceding speed data obtained every 360 degrees in electrical angle. 3. 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 at each predetermined rotation angle of the rotor, and detects the rotation speed of the rotor. And a rotational speed of the rotor, and estimates the rotational angle of the rotor, based on the estimated value of the rotational angle, based on the estimated value of the armature coil current sine wave control is a drive control device of a DC non-commutator motor, when the motor rotates at low speed The rotation angle is estimated using the immediately preceding speed data obtained for each of the minimum electrical angles at which the position signal changes.On the other hand, when the motor is rotating at high speed, the immediately preceding speed data obtained for each predetermined electrical angle larger than the minimum electrical angle is obtained. A drive control device for a DC non-commutator motor, comprising: an estimator for estimating a rotation angle by using the estimator.