JP2005278360A - Brushless motor sensorless controlling method, sensorless controller thereof, and electric pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a brushless motor sensorless controlling method that is efficient and that has small deviation between preset rotational speed and actual rotational speed. <P>SOLUTION: In this brushless motor sensorless controlling method, regular changes are stored that should be taken by the relation of magnitudes of each terminal voltage of stator windings of a plurality of phases to a prescribed voltage, intervals are detected (S12) at the times when the sampled (S4) relation of magnitudes between each terminal voltage and the prescribed one changes, the conduction of the stator windings is controlled on the basis of the regular changes after a delay time based on the intervals from the time of the change, and the delay time is reduced (S22) by a reduction ratio, which becomes higher as rotational speed gets higher. The reduction ratio for every rotational speed is obtained that has different rate of change to the rotational speed of every arbitrary section, the relation is stored of the obtained rotational speed to the reduction ratio, the reduction ratio is obtained (S18, 20) from the relation of the rotational speed (S16) at the time when the intervals are detected (S12), and the delay time is reduced by the obtained reduction ratio (S22). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention stores regular changes to be taken in the magnitude relationship between each terminal voltage of a plurality of phases of stator windings and a predetermined voltage, and samples the magnitude relation between each terminal voltage and the predetermined voltage in time series. Then, the interval at the time when the sampled magnitude relationship changes is detected, and after a delay time based on the interval detected from the time of change, the energization of the stator winding is controlled based on the regular change and the rotation speed is increased. The present invention relates to a sensorless control method for a brushless motor that reduces the delay time with a higher subtraction rate, a sensorless control device for the brushless motor, and an electric pump including the sensorless control device for the brushless motor.

  Recently, brushless motors have been used as electric motors that are mounted on vehicles and drive transmissions, electric pumps of steering devices, and the like. The brushless motor is a motor in which a brush and a commutator are removed from a DC motor and an electronic rectifier circuit is attached. The electronic rectifier circuit detects, for example, the position of the magnet rotor using a magnetic sensor such as three Hall elements, and performs, for example, U phase, V phase, W, etc. by PWM control based on these detection signals. The energization of the three phases is controlled to generate a rotating magnetic field, and the magnet rotor is driven to rotate.

  In order to drive a brushless motor, the rotational position sensor of the rotor is necessary as described above. However, when the motor is mounted in a high-temperature engine room, the heat resistance of the magnetic sensor becomes a problem, and the rotational position sensor is So-called sensorless driving is required to drive the motor without using it. In the sensorless drive, it is necessary to estimate the rotational position of the rotor and create a rotational position estimation signal corresponding to the rotational position signal from the rotational position sensor. Voltage is used.

In sensorless driving of a brushless motor, energization of the stator windings of each phase is normally conducted only at 120 degrees out of the electrical angle of 180 degrees of the positive and negative voltage sections, so-called 120 degrees energization, and the remaining unenergized In the interval of 60 degrees, the induced voltage of each phase is exposed to the terminals of the stator windings of each phase.
Therefore, when the terminal voltage of the stator winding of each phase in this 60-degree section is compared with the reference voltage, the time when they cross in any phase, that is, the time when the zero cross point is related to the rotational position of the rotor It can be. As the reference voltage, a voltage that is half the power supply voltage for energization is used.

In this sensorless drive, the interval between the detected zero cross points is a period corresponding to 60 degrees, and the half of 30 degrees is set as a delay time, and when the delay time is delayed from the zero cross point to the stator winding of each phase. Is switched on.
When the zero-cross point is detected by sampling, the comparison result with the reference voltage is sampled. When the terminal voltage of the stator winding is larger, “1” is set, and when the terminal voltage is smaller, “0” is set. Each comparison result of the V phase and the W phase is patterned like “101” “110”.

There are six types of patterns in the case of three phases, and the six types of patterns are sequentially switched while being continuously detected, and the time when the patterns are switched is detected as a zero cross point.
JP-A-6-70586 Japanese Patent Laid-Open No. 9-233848 JP-A-9-266690 Japanese Patent Laid-Open No. 2002-300792 JP 2002-325484 A JP 2003-111483 A Kazuo Nagatake “Motor Practical Pocket Book Motor / Inverter Technology for Home Appliances” Nikkan Kogyo Shimbun, April 28, 2000

In the sensorless driving of the brushless motor as described above, a phase difference is generated between the induced voltage and the stator winding current as the rotational speed of the motor increases, and the motor efficiency decreases. As this solution, a lead angle control method is used, and conventionally, as shown in FIG. 7, the motor efficiency is improved by changing the lead angle control amount linearly with respect to the motor rotation speed.
However, this conventional method does not eliminate all of the above-described phase differences, and as the rotational speed increases, the set rotational speed (rotation speed of the stator winding current) and the actual rotational speed (rotational speed of the induced voltage). There is a problem that a deviation occurs between.

The present invention has been made in view of the circumstances as described above. In the first invention, there is provided a sensorless control method for a brushless motor that is efficient and has a small deviation between the set rotational speed and the actual rotational speed. The purpose is to provide.
It is an object of the second invention to provide a sensorless control device for a brushless motor that is efficient and has a small deviation between the set rotational speed and the actual rotational speed.
In the third invention, an object is to provide an electric pump including the sensorless control device for a brushless motor according to the second invention.

  A sensorless control method for a brushless motor according to a first aspect of the present invention stores regular changes to be taken between magnitudes of terminal voltages of a plurality of phases of stator windings and a predetermined voltage, and the terminal voltages and the predetermined voltage are stored. Is sampled in time series, and the interval at which the sampled magnitude relationship changes is detected, and after the delay time based on the interval from the time point, the stator winding is changed based on the regular change. In the sensorless control method of the brushless motor that reduces the delay time with a higher subtraction rate as the rotational speed becomes higher while obtaining energization control, the subtraction rate for each rotational speed with a different change rate with respect to the rotational speed for each section is obtained. The relationship between the calculated rotation speed and the subtraction rate is stored, the subtraction rate is calculated from the rotation speed when the interval is detected and the relationship, and the calculated subtraction rate is calculated in advance. And wherein reducing the delay time.

  A sensorless control apparatus for a brushless motor according to a second aspect of the present invention stores regular changes to be taken between magnitudes of terminal voltages of a plurality of phases of stator windings and a predetermined voltage, and the terminal voltages and the predetermined voltage are stored. Is sampled in time series, and the interval at which the sampled magnitude relationship changes is detected, and after the delay time based on the interval from the time point, the stator winding is changed based on the regular change. In the sensorless control device for a brushless motor that controls energization and reduces the delay time with a higher subtraction rate as the rotational speed becomes higher, the subtraction rate for each rotational speed having a different rate of change with respect to the rotational speed for each section is stored. A table, and a rotation speed when the interval is detected and a means for obtaining the subtraction rate from the table, and at the time of the delay at the subtraction rate obtained by the means. Wherein the are without to reduce.

  In the sensorless control method of the brushless motor according to the first invention and the sensorless control device of the brushless motor according to the second invention, the regular change to be taken of the magnitude relationship between the terminal voltages of the stator windings of the plurality of phases and the predetermined voltage is taken. The time relationship between each terminal voltage and the predetermined voltage is sampled in time series, the interval when the sampled magnitude relationship changes is detected, and the delay time based on the interval from the time when the magnitude relationship changes Later, based on regular changes, the energization of the stator winding is controlled, and the delay time is reduced at a higher subtraction rate as the rotational speed becomes higher. The table stores a subtraction rate for each rotation speed with a different change rate with respect to the rotation speed for each section. The obtaining means obtains a subtraction rate from the rotation speed and table when the interval is detected, and subtracts the delay time by the subtraction rate obtained by the obtaining means.

  An electric pump according to a third aspect of the present invention includes the sensorless control device for a brushless motor according to claim 2, a brushless motor that is driven and controlled by the sensorless control device, and a pump that is driven by the brushless motor. To do.

  In this electric pump, the sensorless control device for the brushless motor described in claim 2 drives and controls the brushless motor, and the brushless motor drives the pump.

  According to the sensorless control method for a brushless motor according to the first aspect of the invention, it is possible to realize a sensorless control method for a brushless motor that is efficient and has a small deviation between the set rotational speed and the actual rotational speed.

  According to the sensorless control device for a brushless motor according to the second aspect of the invention, it is possible to realize a sensorless control device for a brushless motor that is efficient and has a small deviation between the set rotational speed and the actual rotational speed.

  With the electric pump according to the third aspect of the invention, it is possible to realize an electric pump including a brushless motor that is efficient and has a small deviation between the set rotational speed and the actual rotational speed.

Hereinafter, the present invention will be described with reference to the drawings showing embodiments thereof.
(Embodiment 1)
FIG. 1 is a block diagram showing the main configuration of Embodiment 1 of a sensorless control method for a brushless motor and a sensorless control device for a brushless motor according to the present invention. This sensorless control device for a brushless motor is a sensorless control device for a brushless DC motor (hereinafter referred to as a motor) that is mounted on a vehicle and drives a hydraulic pump or the like. A phase alternating voltage is generated and the motor 1 is driven and controlled.

The terminal voltages Vu, Vv, Vw of the U-phase, V-phase, and W-phase stator windings (not shown) of the motor 1 are given to the rotational position estimation signal generator 3, and the rotational position estimation signal generator 3 Based on the given terminal voltages, rotational position estimation signals Hu, Hv, and Hw for each phase are created by sampling (digital method).
The rotational position estimation signals Hu, Hv, and Hw are given to the energization control device 4, and the energization control device 4 is based on the given rotational position estimation signals Hu, Hv, and Hw, and the DC voltage of the in-vehicle battery 2 by the one-side PWM method. A three-phase AC voltage is generated from E, and the motor 1 is driven and controlled.

  As shown in the block diagram of FIG. 2, the rotational position estimation signal generation unit 3 includes a voltage comparison unit 12 and a polarity determination unit 14, and the voltage comparison unit 12 includes the terminal voltages Vu, Vv, Vw, and an in-vehicle battery. Comparators 15u, 15v, and 15w are respectively provided for comparing with a voltage Va that is ½ of the DC voltage E of 2. The comparison results of the comparators 15u, 15v, and 15w are digital signals Bu, Bv, and Bw that are “1” when the terminal voltages Vu, Vv, and Vw are larger and “0” when the terminal voltages are smaller. For example, the polarity determination unit 14 samples at a frequency of 19.23 kHz.

  The polarity determining unit 14 is provided with the detected rotational speed value S of the rotor of the motor 1 and is constituted by an MPU having a memory 14a and a timer 18. The memory 14a has rules for taking patterns of digital signals Bu, Bv and Bw. I remember the changes. Further, based on the zero-cross point detected based on the change in the pattern of the sampled digital signals Bu, Bv, Bw and the regular change stored in the memory 14a, the rotational position estimation signals Hu, Hv, Hw of the respective phases are obtained. It is created and given to the energization control device 4.

  The memory 14a has a table as shown in FIG. 3 in which a subtraction rate (advance angle control amount) for reducing the delay time for delaying the rotational position estimation signals Hu, Hv, Hw from the detected zero cross point according to the rotational speed is determined. 17 is stored. When creating the rotational position estimation signals Hu, Hv, and Hw, the polarity determination unit 14 reduces the delay time by a subtraction rate corresponding to the rotational speed detection value S at that time. The table 17 is prepared in advance by obtaining a subtraction rate for each rotation speed based on actual measurement so that the efficiency of the motor 1 is improved, and the subtraction rate differs in a change rate with respect to the rotation speed for each arbitrary section. .

The energization control device 4 includes an energization signal generation unit 5, a PWM control unit 7, a gate drive circuit 8, a switching circuit 9, and a speed control unit 16.
The switching circuit 9 includes a semiconductor switching element 6u +, 6v +, 6w + connected to the anode side of the in-vehicle battery 2 and a semiconductor switching element 6u connected to the cathode side of the in-vehicle battery 2 for each of the U phase, the V phase, and the W phase. −, 6v−, 6w− are connected in series. Each connection point is connected to a terminal of the stator winding of the motor 1 for each phase. Free wheel diodes (flyback diodes) are connected in antiparallel to the semiconductor switching elements 6u +, 6u−, 6v +, 6v−, 6w +, 6w−, respectively.

The speed control unit 16 compares the rotation speed detection value S and the rotation speed setting value Sa of the rotor of the motor 1 and creates a speed control signal Spwm for PWM driving the motor 1 based on the magnitude relationship between the two. This is given to the PWM control unit 7.
The energization signal generator 5 energizes the semiconductor switching elements 6u +, 6u−, 6v +, 6v−, 6w +, 6w− of the switching circuit 9 based on the given rotational position estimation signals Hu, Hv, Hw of the respective phases. The energization signals Cu +, Cu−, Cv +, Cv−, Cw +, Cw− for control are created and given to the PWM control unit 7. The energization signal generation unit 5 is configured by an MPU or a logic element.

The PWM control unit 7 performs PWM control signals Du +, Du−, Dv +, Dv−, and PWM control for the semiconductor switching elements 6u + to 6w− based on the supplied energization signals Cu + to Cw− and the speed control signal Spwm, respectively. Dw + and Dw− are created and given to the gate drive circuit 8.
The gate drive circuit 8 drives the semiconductor switching elements 6u + to 6w− on / off based on the given PWM control signals Du + to Dw− to generate a rotating magnetic field in the stator winding of the motor 1.

Hereinafter, the operation of the sensorless control device for the brushless DC motor having such a configuration will be described with reference to the flowchart of FIG.
Each terminal voltage Vu, Vv, Vw of the U-phase, V-phase, and W-phase stator windings of the motor 1 is 120 degrees in phase as shown in the waveform diagrams of FIGS. Of the electrical angles of 180 degrees that are the positive and negative voltage sections, a section of 120 degrees in the center is energized, and ringing occurs at the end of each energized section. In the section other than 120 degrees in the central portion, the induced voltage generated in the stator winding is exposed.

  The comparators 15u, 15v, 15w of the rotational position estimation signal generation unit 3 are respectively connected to the terminal voltages Vu, Vv, Vw of the stator windings of each phase of the motor 1 and a voltage Va that is ½ of the DC voltage E of the in-vehicle battery 2. Are compared. These comparison results are sampled by the polarity determination unit 14 as digital signals Bu, Bv, and Bw that are “1” when the terminal voltages Vu, Vv, and Vw are larger and “0” when they are smaller. Is done.

The digital signals Bu, Bv, and Bw regularly change in the order of (101) → (001) → (011) → (010) → (110) → (100) → (101), for example. The periodic time during which the six patterns of the digital signals Bu, Bv, and Bw change regularly is sufficiently larger than the sampling period.
The memory 14a of the polarity determination unit 14 stores the order in which the patterns of the digital signals Bw, Bv, and Bu described above change regularly.

  The polarity determining unit 14 first disables interrupts from other sources (S2 in FIG. 4), then samples the digital signals Bu, Bv, Bw (S4), and based on the pattern of the sampled digital signals Bu, Bv, Bw, A procedure for detecting the zero-cross point is executed (S6). The procedure for detecting the zero-cross point is, for example, that the zero-cross point is detected when the pattern of the digital signals Bu, Bv, and Bw is changed, and the changed pattern continues in a plurality of samplings.

  The polarity determination unit 14 returns (S8) when the zero cross point is not detected in the procedure (S6) of detecting the zero cross point (S6). When the zero cross point is detected, the timer 14b finishes counting from the previous zero cross point detection (S10), and the zero cross point interval Tz that is the time measured is detected (S12). The zero cross point interval Tz corresponds to an electrical angle of 60 degrees. Next, the timer 14b starts counting from the current zero-cross point detection (S14).

Next, the polarity determination unit 14 reads the rotational speed detection value S (S16), and refers to the table 17 as shown in FIG. 3 based on the rotational speed detection value S (S18).
The polarity determination unit 14 refers to the table 17 (S18), and determines the advance angle control amount Ta ((Tz / 2) × (subtraction rate / 100)) corresponding to the rotation speed detection value S (S20). Next, the delay time Td = (Tz / 2) −Ta is calculated to determine the delay time Td (S22), then an interrupt from another is permitted (S24), and the process returns.

  The polarity determining unit 14 delays the output signals (sampled signals) of the comparators 15u, 15v, and 15w by the determined delay time Td (S22) based on the regular change of the pattern stored in the memory 14a. The rotation position estimation signals Hu, Hv, and Hw for each phase are generated and supplied to the energization control device 4. The rotational position estimation signals Hu, Hv and Hw include positive / negative energization / non-energization information of each phase based on the timing of switching energization and the regular change of the pattern stored in the memory 14a.

The energization signal generator 5 of the energization controller 4 stores six types of control patterns of the semiconductor switching elements 6u + to 6w− based on the rotational position estimation signals Hu, Hv, Hw, and the given rotational position estimation signal Hu. , Hv, Hw and this control pattern create energization signals Cu + to Cw−. The generated energization signals Cu + to Cw− are given to the PWM control unit 7.
The PWM control unit 7 generates PWM control signals Du + to Dw− for PWM control of the semiconductor switching elements 6u + to 6w− by the one-side PWM method based on the supplied energization signals Cu + to Cw− and the speed control signal Spwm. To the gate drive circuit 8.

The gate drive circuit 8 outputs drive signals for controlling on / off of the semiconductor switching elements 6u + to 6w− of each phase by the one-side PWM method based on the given PWM control signals Du + to Dw−. A rotating magnetic field is generated in the stator winding, and the magnet rotor is driven to rotate.
In the above-described embodiment, the motor 1 is driven and controlled by the one-side PWM method. However, the sensorless control method and the sensorless control device for the brushless motor according to the present invention are not based on the both-side PWM method and the PWM method. It is also possible to apply.

(Embodiment 2)
FIG. 6 is a block diagram showing a main configuration of the electric pump according to the second embodiment of the present invention and its peripheral portion. This electric pump is used for an automatic transmission of a vehicle, and an automatic transmission 21 connects a crankshaft (not shown) of the engine 20 and a propeller shaft 24.

The electric pump 22a includes a pump 22 fixed to the side surface of the automatic transmission 21, the brushless DC motor 1 that drives the pump 22, and the sensorless control device 23 described in the first embodiment that controls driving of the brushless DC motor 1. It has.
The electric pump 22 a controls the pressure of oil that operates the automatic transmission 21.

The rotation of the end of the crankshaft of the engine 20 on the side not connected to the automatic transmission 21 is transmitted to the pulley 31 via the electromagnetic clutch 32, and the rotation of the pulley 31 is caused by the belt 33 to generate the generator 28 and the auxiliary machine 30. Is transmitted to. The auxiliary machine 30 is an air conditioner compressor or the like. The electric power generated by the generator 28 is stored in the in-vehicle battery 29 and becomes a power source for the sensorless control device 23 and the like.
The end of the propeller shaft 24 that is not connected to the automatic transmission 21 is connected to the drive shaft 26 of the drive wheel 27 by a differential 25 at a right angle.

It is a block diagram which shows the principal part structure of embodiment of the sensorless control method of the brushless motor which concerns on this invention, and the sensorless control apparatus of a brushless motor. It is a block diagram which shows the structural example of a rotation position estimation signal production | generation part. It is a characteristic view which shows the relationship between the motor rotational speed of the sensorless control apparatus of the brushless motor which concerns on this invention, and a lead angle control amount. It is a flowchart which shows the example of operation | movement of a polarity determination part. It is a wave form diagram which shows the terminal voltage of a stator winding. It is a block diagram which shows the principal part structure of embodiment of the electric pump which concerns on this invention, and its peripheral part. It is a characteristic view which shows the relationship between the conventional motor rotational speed and a lead angle control amount.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 (Brushless DC) motor 2,29 Car-mounted battery 3 Rotation position estimation signal generation part 4 Energization control apparatus 5 Energization signal generation part 6u +, 6u-, 6v +, 6v-, 6w +, 6w- Semiconductor switching element 7 PWM control part 8 Gate Drive circuit 9 Switching circuit 14 Polarity determination unit 14a Memory 14b Timer 15u, 15v, 15w Comparator 16 Speed control unit 17 Table 18 Timer 20 Engine 21 Automatic transmission 22 Pump 22a Electric pump 23 Sensorless control device 24 Propeller shaft

Claims (3)

A regular change to be taken of the magnitude relationship between each terminal voltage and a predetermined voltage of the stator windings of a plurality of phases is stored, and the magnitude relation between each terminal voltage and the given voltage is sampled in time series, sampling The interval at which the magnitude relationship is changed is detected, and after the delay time based on the interval from the time, the energization control is performed on the stator winding based on the regular change, and the subtraction increases as the rotational speed increases. In a sensorless control method of a brushless motor that reduces the delay time by a rate,
The subtraction rate for each rotation speed with a different rate of change with respect to the rotation speed for each section is obtained, the relationship between the obtained rotation speed and the subtraction rate is stored, and the rotation speed when the interval is detected A sensorless control method for a brushless motor, wherein the subtraction rate is obtained from a relationship, and the delay time is reduced by the obtained subtraction rate. A regular change to be taken of the magnitude relationship between each terminal voltage and a predetermined voltage of the stator windings of a plurality of phases is stored, and the magnitude relation between each terminal voltage and the given voltage is sampled in time series, sampling The interval at which the magnitude relationship is changed is detected, and after the delay time based on the interval from the time, the energization control is performed on the stator winding based on the regular change, and the subtraction increases as the rotational speed increases. In a sensorless control device for a brushless motor that reduces the delay time by a rate,
A table storing the subtraction rate for each rotation speed having a different rate of change with respect to the rotation speed for each section; and a means for obtaining the rotation speed when the interval is detected and the subtraction rate from the table, A sensorless control device for a brushless motor, characterized in that the delay time is reduced by the subtraction rate obtained by (1).   An electric pump comprising the sensorless control device for a brushless motor according to claim 2, a brushless motor that is driven and controlled by the sensorless control device, and a pump that is driven by the brushless motor.

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