TW453020B - Motor position driving method without magnetic pole detecting apparatus - Google Patents

Abstract

The present invention relates to a kind of motor position driving method without magnetic pole detecting apparatus, and mainly uses voltage-source frequency converter in combining with appropriate switching technique to directly control the magnetic flux of brush-less synchronous motor stator coil and generate arbitrary stator space magnetic field vector so as to attract the rotator of permanent magnetic type brush-less synchronous motor and reach the purpose of step-type open-loop positioning control. The method stated above does not require any apparatus for detecting magnetic pole position, and can make each sort of permanent magnetic type synchronous motor to obtain the purposes of micro step positioning control and governing speed control. In addition, good governing speed control also can be obtained when this method is applied in the inductive motor. Because no device for detecting magnetic pole is required, under the cooperation of appropriate software program, the invented frequency conversion technique can be suitable for use in positioning and governing speed control of permanent magnetic type brush-less motor, and in governing speed control of the AC inductive motor.

Description

453020 A7 U printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs: 5. Description of the invention (f) The present invention relates to a micro-stepping control method of a permanent magnet synchronous motor, especially a permanent magnet synchronous motor as a control object With the sine wave pulse

Wide modulation (Sinusoidal Pulse Width Modulation, SPWM) or Space Voltage Vector Pulse Width Modulation (Voltage Space Vector PWM VSVPWM) and variable frequency switching technology 'In addition to having the advantage of simplifying the drive circuit, the motor does not need to be equipped with a magnetic pole detection device, You can get quite good positioning control accuracy. This technology can be applied to speed control of induction motor at the same time. As early as the 1920s, "stepping motors have been successfully applied to the positioning control of torpedoes and turrets on warships". This type of motor has the characteristics of open-loop control. It has been developed in a wide range of applications so far. "Due to the unique motor characteristics of stepper motors, The positioning function can only be obtained under open-loop control, but its positioning accuracy, dynamic response and output power still cannot compete with general DC brushed or brushless motors controlled by closed loop. Therefore, many studies have been devoted to the closed-loop control of stepper motors. However, the introduction of closed-loop control will increase the complexity of the system and the difficulty of maintenance. At the same time, the original purpose of the simple driving circuit is lost. Therefore, under the premise of low manufacturing cost and simple control circuit, improving the dynamic characteristics of the existing stepping motor to meet the needs of the precision industry is a direction worthy of consideration and research; in addition, 'how to make the general high-power permanent magnet synchronous The motor also has the effect of micro-step positioning, which is also an important subject worthy of discussion.

The so-called permanent magnet synchronous motor (Permanent_Magnet Synchronous Motor) refers to a brushless motor whose rotor is a permanent magnet and the back EMF waveform is a sine wave or a sine-like wave (called "sinusoidal"), usually using a sine wave Pulse width modulation (spwM 3 This paper size is applicable to China National Standard (CNS) A4 specification (21〇X 297 public love), (Please read the items on the back before filling this page} 453020 Λ7 Π7 V. Description of the invention (_ >)

Sinusoidal puise width Modulation (SPWM) method to control the input voltage, and then generate a sine-wave-like current, so that the direction of the magnetic field generated by the stator coil can be continuously changed; during operation, the stator magnetic field and the rotor magnetic field operate synchronously, so it is called permanent magnet synchronous motor. From the perspective of mechanical structure, the permanent magnet synchronous motor is quite similar to the permanent magnet stepping motor. Only the stepping motor is designed to meet the smaller step angle control. Therefore, the design of the rotor core and the stator core must be fine. Gear, so the process of stepping motor is more complicated. In comparison, the mechanical structure of permanent magnet synchronous motors is relatively simple. Therefore, using the simple mechanical structure and high output power of permanent magnet synchronous motors, if it can give the same positioning characteristics as stepper motors, it will be effective. Reduce costs and increase applications. The conventional permanent magnet synchronous motor drive architecture is shown in Figure 11. In order to enable the motor to achieve constant speed or positioning control, an encoder or Hall element is generally used as the rotor magnetic pole position detection. To the driver 'is really a closed loop control architecture. The structure of the voltage source inverter widely used in industry is shown in Figure 8. It is mainly composed of multiple sets of changeover switches in the form of upper and lower arms. In order to prevent the upper and lower arms of the inverter from turning on at the same time, the upper and lower arms of the switches are reversed from each other, that is, the upper arms of the switches (DPTHa ~ DPTHc) are 1 ( high), the lower arm switch (DPTHa_ ~ DPTHc_) is 0 (i0w). When using a frequency converter as an AC frequency conversion output device, it is usually necessary to consider some “solid loss” including the voltage drop of the power device (Voltage drop of power device) and short-circuit protection time (hereinafter referred to as dead-4) This paper standard is applicable to China Standard (CNS) A4 specification (210 X 297 mm) ------------ Outfit -------- Order --------- 0 (Please read the back first (I will fill in this page again with the meaning of x)) 453020 A7 07 Printed by the agency of the Intellectual Property Bureau of the Ministry of Economic Affairs 5. Printed by the company, etc. 5. The so-called dead_ti [Re refers to the prevention of crystal switching when the inverter is switched. Turn-on delay time (turn-on delay time) and turn-off delay time (tUrn-off delay tlrae 丄 〇, cause the upper and lower arm switch to be short-circuited at the same time, and the crystal is damaged. Therefore, a moment must be added at the moment of the switch trigger signal switch Short-circuit protection time (fine-⑽) to ensure that the upper and lower arm ㈣ switches will not be short-circuited. However, when d is added, the actual voltage output will be distorted (dist0). The second is for three-phase inverters. Dead_time distortion is discussed. 4 See also As shown in the ninth figure (only one arm of the voltage source inverter is disclosed), when the upper and lower arm switches of the inverter power stage are switched, depending on the current polarity, the four switching states that can occur are as follows: When the current h > 0 At time, T "switches from on to off, and Ta passes from dead to ti: and then switches from off to on (as shown in the sixth area of the tenth icon). At this time, the actual output voltage VAN is the same as the ideal output voltage, so dead —time No error was caused. However, when the current iA > 〇a, I is switched from ON to ON after switching off, and L is switched from ON to OFF after switching on (as shown in area B of the tenth icon). The actual output voltage ViN is compared with the ideal output voltage, and the area shown by the slanted line is lost. At the current iK0, τ "switches from off to on after dead-time, and L switches from on to off after the dead-time (as shown in the tenth icon D area (Shown) 'At this time, the actual output voltage is the same as the ideal output voltage, so there is no error. At the current h <. Ri Ding, and Ding "Switch from on to off" L- After dead-time switch from off to on (such as First The area indicated by the figure indicates C)) At this time, the actual output voltage ^ is increased compared to the ideal output voltage, and the area shown by the diagonal line is added. This paper size applies to the national standard (CNS) A4 size (½ x 297 male cage M, --------------- (Please read the notes on the back before filling out this page) Nickel 453 0 20 Economic Shao Intellectual Property Bureau S, printed by Industrial Consumers & Cooperatives Λ7 B7 V. Explanation of the invention (pregnancy) From the above analysis, it can be known that at the current i A > 0, there is a voltage loss in each pulse-width modulation (PWM) carrier cycle, and the amount of this voltage loss is related to the dead-time setting; the same "Current iA < 〇, each PWM carrier cycle has a voltage increase, and its size is related to the dead_time variable value" means equivalent to the area of the oblique line in the tenth figure, and this error amount is evenly distributed Each carrier period, that is, the average distortion of the output voltage is Γ + yVdc iA < ° ^ AN = l is ~~ Vdc iA > 〇

Ts dc In the above formula, t δ is the dead-1 ime set value, Ts is the PWM carrier period, and Vdc is the DC BUS voltage. Obviously, if the DC BUS is a fixed value, the output voltage distortion of the three-phase inverter is proportional to the value of t △ and the switching frequency (switching frequency = 1 / Ts), that is, the higher the switching frequency is dead-1 i The longer the me time, the more obvious the effect of distortion 'is related to the polarity of the phase current. On the other hand, the amount of distortion caused by dead-time will affect the fundamental wave of the output voltage and introduce low-frequency harmonics. When the motor is running at low speed, the effect of the low-frequency waves will be more obvious. From the fourth figure, it can be seen that due to the effect of dead_time, the error between the ideal voltage and the actual voltage. The main purpose of the present invention is to use VSVPWM and improved SPWM frequency conversion switching technology to apply to the open circuit positioning of general permanent magnet synchronous motors, so that the permanent magnet synchronous motor also has a control method of open circuit positioning characteristics. Among them, the compensation method for the short-circuit protection time (dead-Ume) effect is to directly detect the current. 6 The paper size is applicable to the Chinese National Standard (CNS) A4 specification (21〇x 义 7mm) -------- ------ ϊ 衣 · ------- Order · -------- Green < Please read the note on the back first; > Fill in this matter and fill in this I) 453020 Intellectual Property of the Ministry of Economic Affairs Printed by the Consumer Cooperative of the Bureau Λ7 V. Description of the invention (j ~) The pole (· and the compensation of each phase according to the polarity of the current or subtract a correction denier. P ^ ^ ^. That is, when the current is less than 0, PWM The command is to subtract (or translate down) a correction amount; when the current is greater than ◦, add (or translate up) a correction amount. Second, for the purpose of A, the main control steps of VSVPWM frequency conversion switching technology include: : The step of using the pulse width modulation average output ㈣ idea 'and converting the arbitrary space voltage vector on the plane according to the aforementioned multiple sets of basic space voltage vectors; a step of using the arbitrary space voltage vector obtained by the above steps to rotate the synchronous motor to a predetermined Step of position; any space voltage vector described in month 1) is composed of two sets of adjacent basic voltages The amount of synthetic achieved. The main control steps using the improved SPWM frequency conversion switching technology of the present invention include: the step of defining a string-shaped voltage waveform by using the concept of the inverter and the pulse width modulation average output voltage;-determining the stator rotating magnetic field according to the aforementioned string-type voltage and frequency Steps of size and frequency; a step of rotating the motor to a predetermined position according to the foregoing steps and given position information (the SPWM frequency conversion switching technology is not used for this function). According to the aforementioned method, the step angle can be divided infinitely in theory as a micro-stepping drive to achieve the same effect as a stepping motor. In addition, the excitation energy can be changed to apply to loads of different sizes. The size of this paper applies the national standard (CNS) A4 specification (2i0x 297 mm). ------- 1τ --------- broken (please read the precautions on the back first) (Fill in this page again) 453 0 2 0 A7 ------- B7___ 5. Description of the Invention (&) The second purpose of the present invention is to provide an open loop control architecture that does not require any motor rotor position sensing device. Make the permanent magnet synchronous motor achieve micro-step positioning, speed ㈣, or make the induction motor speed control, which can reduce the hardware cost of the magnetic pole position detection device. In order to make your reviewing committee better understand the aforesaid purpose and the technical characteristics of the present invention, the detailed description is attached as follows: (I) Schematic part: The first picture: the switching state, phase voltage and line voltage of each switch of the inverter Output the correspondence table. The second figure is the geometric relationship diagram of the six basic space voltage vectors of the inverter. The third figure: the relationship between the reference vector and the basic vector of the system and the inverter < The fourth figure is a graph of the effect of short-circuit protection time on the output voltage. Fifth figure: Comparison table of VSVPWM and SPWM frequency conversion switching technology. The sixth diagram is a schematic diagram of an open-loop positioning system according to a possible embodiment of the present invention. The seventh figure is a working flowchart of compensating for the short-circuit protection time effect. Figure 8: The structure of the inverter. Figure 9: Schematic diagram of one arm of a three-phase inverter. Fig. 10: It is a schematic diagram of the short-circuit protection time effect of the inverter. The eleventh figure is the control architecture diagram of the conventional permanent magnet synchronous horse. The twelfth figure is the control architecture diagram of the conventional SPWM frequency conversion switching technology. The thirteenth figure is a control architecture diagram of an improved SP dragon inverter switching technology of the present invention. Β (II) Figure number part: 8 This paper scale is applicable to China National Standard (CNS) A4 specification (210: 297 public meals)-- ---- I i I. &Quot; · ϊ -----— Order- — ™ — · (Please read the notes on the back before filling out this page) 4 5302 Printed by the Consumer Cooperatives of the Wisdom and Time Bureau of the Ministry of Economic Affairs Λ7 137 V. Description of the invention (7) (10) Digital signal processor (1 1) A / D conversion interface (20) Frequency conversion 11 (30) Synchronous motor (3 1) Current sensor The present invention mainly uses an improved type SP test or vsvp test variable frequency switching technology: control 7 under-magnetic synchronous motor or general stepper motor for micro-step positioning control or speed control, can also make the induction motor gain speed control. In terms of VSVPWM frequency conversion switching technology, please refer to Figure 8 for its architecture. The switching states of the switches on the upper and lower arms are corresponding to the phase voltage and line voltage output as shown in the first chart. The chart expands the eight switching states in order on the plane, and the position relationship of each vector can be obtained (as shown in the second figure). From the second figure, it can be found that the corresponding output of the eight switching states of the inverter on the plane is The six are the same size, but the phases differ by 60. The plane non-zero vector (Qiao,) and two zero vectors (vs) with zero output. The six groups of plane vectors (Qiao, Qiao, called basic space voltage vectors), when they are turned on in sequence, can produce a The continuous rotating magnetic field causes the synchronous motor to continuously rotate. The basic principle of the VSVPWM frequency conversion switching technology is the same as the average output voltage concept of the pulse width modulation (PWM). The difference is that the PWM output is only the DC voltage level. Control, and VSVPWM includes space vector control of voltage magnitude and angle. From the concept of average value of pulse width modulation, it can be known that when the switching frequency is higher, the output voltage of pulse width modulation will be closer to its average value. Use this average Concept, in combination with the six basic voltage vectors described above, an arbitrary plane can be synthesized from two adjacent basic voltage vectors'. This paper size is applicable to the standard. (〇yJS) A4 specification (210 * 297) ---------------- (Please read the Jiang Yi matter on the back before filling this page) ¢ 53020 A7 Five 'invention description (f) Two voltages are oriented. Take the third picture As shown, two adjacent basic voltage vectors are 0. 60 is , By the following mathematical formula describes how to determine the respective conduction times of two vectors to be:,

Jref ^ ~ Vi ^ + Γ, Λ In the above formula, Tz is the carrier period; Tm is the on time of state 1; T2 is the on time of state 2; Tz-(Τ1 + Τ2) is the on time of the zero vector. When the switching frequency is fast enough, the instantaneous output within a single switching period can be regarded as a constant, so the previous formula can be equivalent to: h-Ti + v2.T2 + v7. [Tz-(Tl + l2) > -reftTz v2 dt + ^ + 7, ν7 (ν8) Λ is also a vector of zero, and I is the component of the plane coordinate 'can be simplified as: ▽ 2 I = ¾' decompose it (please read the -Issue on the back before filling in (This page) + ΤΊ cos 60 sin 60

V ref vdc

Tz cosylsmr * I --------- Order --------- Transferred to the Intellectual Property Bureau of the Ministry of Economic Affairs, printed by P · Industrial Cooperative Cooperative, so it can be solved from the above simultaneous equations: r_Tz sin 60 τ2 = τζ sin (60- /) sin 60 Therefore, the on-time of each basic vector corresponding to each interval can be obtained. Therefore, the voltage vector at any angle on the plane can be printed by the space voltage vector pulse width. The paper size is applicable to the Chinese National Standard (CNS) A4 specification (210 X 297 Gongchu) 453020 Λ7 Γ 经济 7 Economic and Intellectual Property Bureau Employee Consumer Cooperatives Description of the Invention (The method of tuning can be used to find 'that is, the corresponding space magnetic field vector can be obtained by the aforementioned six basic vectors.' To achieve the function of motor positioning. VSVPWM variable frequency switching technology method has the following characteristics: 1 Only We / adjacent two states and a zero vector are switched. 2 _ Only need to give (carrier time), α and γ (angular position), The position of the stator coil magnetic field on the plane can be determined. 3 'When used as a micro-step drive', theoretically, the step angle can be divided indefinitely. 4 'If the motor load increases, the excitation energy can be changed (ie, ^, to Corresponding to different load sizes. As a result of VSVPWM variable frequency switching technology, it is applied to permanent magnet synchronous motor control. A new switching technology As compared with the traditional sine wave pulse width modulation method used to control permanent magnet synchronous motors (as shown in Figure 5), in terms of DC BUS utilization, current harmonics, crystal switching loss, and implementation complexity, etc. ' The difference can be seen. For the improved SPWM frequency conversion switching technology of the present invention, the method is similar to the conventional SPWM (as shown in Figure 12), and the difference can give the position information of the space magnetic field vector, so that The motor rotor can be used for positioning control. The implementation method lies in software planning. By counting the rotation angle of the rotating magnetic field, and when the rotation angle reaches the required position command angle, the output of the three arms of the variable frequency number is sent to a fixed DC value (such as the first (Figure 13), to fix the stator magnetic flux at the required rotation position. The input required for this method is 11 This paper size applies to China National Standard (CNS) A4 (210 x 297 mm)- ---------- Install · ------- Order ---------- ^ (Please read the notes on the back before filling this page) 45302 Intellectual Property Bureau of the Ministry of Economic Affairs Consumption 1 printed by the company A7 U7 V. Description of the invention ((〇 ) 叫, called, (1, where 屮 determines the amplitude of the sine wave, which is the same as VSVPWM 'adjustable 屮 responds to different external loads; called determines the angular frequency of the rotating magnetic field; q determines the positioning angle of the space magnetic field. As described in the background of the invention The specific frequency conversion switching technology is applied to the motor positioning control. Please refer to the sixth figure, which is mainly controlled by a digital signal processor (1 0) through a frequency converter drive stage (2 0) to control the synchronous motor (3 0). Run 'The synchronous motor (30) passes a current sensor (31) to detect the phase current and feed it back to the digital signal processor (work 0), and transmits it through the built-in A / D conversion interface (11). The digital signal processor (10) is used to judge its current polarity, and the compensation value is obtained after conversion, which is used as the compensation basis for the PTO input command. As for the specific flow of the aforementioned compensation method, please refer to Figure 7. From the above description, it can be seen that the specific technical means of the present invention has at least the following advantages with these designs: 1. It can control a permanent magnet brushless synchronous motor with a simple structure and high output power, generating micro-stepping like a stepping motor Positioning effect, so it can improve the rejection and reduce the cost. 2. Rotor magnetic pole position detection element is not needed, which can simplify the driving circuit. The open-loop method can be applied to the driving of permanent magnet synchronous motor and AC induction motor at the same time. 3. The compensation method can effectively solve the problem of improving the output voltage distortion after the inverter is added with short-circuit protection time (dead-time). In order to enable # review committee members to further understand the characteristics of the present invention and the differences between the technical content and conventional technology, please refer to the following description in conjunction with the drawings. 12 This paper size is applicable to the Chinese National Standard (CNS) A4 specification (210 X 297 cm). ) Install -------- Order --------- 嫂 ', (Please read the first; please read the back of the matter; please fill in this page) Printed by the Intellectual Property Bureau Employee Consumer Cooperative of the Ministry of Economic Affairs 45302 〇Λ7 ____J37__ 5. Explanation of the invention (/ 7). The inverter modulation technology used in the conventional AC servo motor driver is sine wave pulse width modulation (lake), and its application level is generally not limited to generating a fixed size rotating magnetic field (three-phase current electrical angle phase phase i 12〇., The two phases are phase I 90.) 'does not fix the rotating magnetic field space vector at any position (as shown in Figure 12). In the present invention, through the software programming of the microprocessor, the stator's rotating magnetic field of the permanent magnet synchronous motor can be arbitrarily fixed at a specific space vector position. There are two methods proposed by the present invention; it is to use SPWM and use software functions. Count the rotation angle of the rotating magnetic field (given ^, then A =, and fix the SPWM input when the rotation angle reaches the required position command (as shown in Figure 13), which means that the output of the two arms of the inverter is fixed The equivalent DC value makes the stator magnetic field fixed accordingly. The second is to use the space voltage vector pulse width modulation (as shown in the second figure). This modulation method can directly specify the magnetic field in the space at any fixed position to achieve control. The purpose of the magnetic field vector, therefore, through the software planning, the rotating magnetic field of the motor stator can be fixed at the required position command. The magnetic field angle planned in the software is the electrical angle, which is a factor of one from the mechanical angle of the rotor of the motor! (Ie 4 = ^ meaning), where t is the number of motor poles, ^ is the electrical angle, and 'is the mechanical angle. From the above analysis, we can know that controlling the stator magnetic field rotation angle can control the permanent magnets. The mechanical rotation angle of the step motor rotor achieves the purpose of open-loop positioning and micro-stepping. The open-loop speed regulation function is similar to the concept of open-loop positioning. By controlling the magnetic field rotation frequency of the permanent magnet synchronous motor, the mechanical rotation frequency of the rotor can be controlled. Paper size applies to Chinese National Standard (CNS) iri; grid (2i0 x 297 public love)-: --- order -------- order ------------ ^ (please read the back first Please note this page before filling in this page) 4 5 3 〇2 ό Λ7 " " '-------------- V. Description of invention (/)) rate. No magnetic pole position detection is required. The software mode of the microprocessor can be used to switch, so that the overall hardware structure does not need to be changed, and it can be suitable for driving many different types of motors at the same time, such as induction motors, stepping motors, synchronous motors, etc. , Can become a universal motor driver. Therefore, the present invention is a motor driving method with 1 k-bit position power, which includes the use of νπρψΜ or improved SPWM frequency conversion switching technology, which can achieve motor open-loop positioning, speed regulation, and micro-stepping functions. In summary, the present invention can indeed achieve the advantages as described above, which has significantly improved compared with the traditional synchronous motor control method, so it has both industrial applicability and progress, and meets the invention patent For the essentials, Yi filed an application in accordance with the law. Those who need to be aware of the above are the preferred and specific embodiments of the present invention. If the changes made according to the concept of the present invention and the functional effects do not exceed the spirit covered by the description and illustration, Within the scope of the present invention, 'Ming Chen Ming. Install -------- Order ---------- Transfer (Please read the precautions on the back before filling out this page)

4 H This paper size applies to China National Standard (CNS) A4 (210 * 297 mm)

Claims (1)

Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs 453〇2〇Λ3 B8 C8 __ D3, patent application scope 1. A motor positioning and driving method without magnetic pole detection device, using space voltage vector pulse width modulation (VSVPWM) or improved Sine wave pulse width modulation (SPWM) frequency conversion switching technology is the main control method, which includes: First, use the concept of average output voltage of pulse width modulation, and directly change inward according to multiple sets of basic two-phase electricity to get the plane A step of performing an arbitrary space voltage vector; a step of determining a rotor position of the permanent magnet synchronous motor by using the arbitrary space voltage vector obtained in the foregoing steps. 2 · According to the method of positioning and driving the motor without magnetic pole detection device described in item 1 of the scope of patent application, the frequency conversion switching technology compensates for the short-circuit protection time (dead_time) effect, and mainly detects the phase current polarity of the motor directly, and according to The current polarity is the pwM reference command value for each phase, plus or minus a correction amount. 3. According to the method of driving the motor position of the non-magnetic pole detection device as described in item 2 of the scope of the patent application, when the current is less than 0, the P command is input to subtract (or translate downward) a correction amount; When the current is greater than 0, a correction amount is added (or called upward translation). 4 _ A method for positioning and driving a motor without a magnetic pole detection device, which mainly uses space voltage vector pulse width modulation (VSVPWM) or modified sine wave pulse width modulation (SPWM) frequency conversion switching technology as the main control method, which includes: First, use the concept of pulse width modulation to average the output voltage, and directly change the different two voltages to 1 according to multiple sets of basic two voltages to obtain an arbitrary space voltage vector on the plane; Use any space voltage vector obtained in the previous step to determine the induction horse_ ________ 15 Private paper size applies to 117 national standards (CNS) A4 specifications (210 X 297 public hair). Factory clothes -------- order --------- line. (Please read the back first & for the matters needing attention, fill in this page again) 53〇2 AS B8 C8 D8 VI. Steps for applying patents to reach the rotor position; Therefore, the aforementioned frequency conversion switching technology is applicable to all types of permanent magnet synchronous motors in order to obtain positioning drive, micro Step positioning control and speed control, and is suitable for speed control of induction motor, so that a motor driver can be applied to different types of motor drive applications at the same time without changing its hardware structure, becoming a synchronization and sense General-purpose drive device for application motor α 5 · As in the method for positioning and driving a motor without a magnetic pole detection device as described in item 4 of the scope of patent application, the frequency conversion switching technology compensates for the short-circuit protection ded-time effect, mainly directly Detect the phase current polarity of the motor, and add or subtract a correction amount 3 6 'according to the pwM reference command value of each phase. 3' Positioning drive of the motor without magnetic pole detection device as described in item 5 of the scope of patent application Method 'When the current is less than 0, the pw} 1j command is input to subtract (or shift down) a correction amount; when the current is greater than 0', add (or shift up) a correction amount. 16 Please read the -Issue on the back before filling in this page) .. 4 -------- Order ----- Thread and Winter Paper Standard Applies to Chinese National Standard (CNS) A4 Specification (210 X 297) cage