JP2005295746A - Motor controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor controller which has high resistance to noise at a terminal voltage detection time. <P>SOLUTION: An energization pattern switching time is obtained from phases (θeu, θev, and θew) of induced voltages (Eu, Ev, and Ew) included in terminal voltages (Vu, Vv, and Vw) and a motor rotating speed (ω) based on the amount of the change of the phase. When arrived at this conducting pattern switching time, a present conducting pattern is switched to a next conducting pattern. Resistance to noise at the terminal voltage detection time is high. Thereby, expected conducting pattern switching can be properly performed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a motor control device that controls rotation of a sensorless synchronous motor by rectangular wave driving.

In rotation control of a sensorless synchronous motor driven by a rectangular wave, for example, a brushless DC motor having no sensor for detecting the rotor position, the terminal voltage of the stator coil is detected during a non-energization period, and the induced voltage included in this terminal voltage In general, a method is employed in which the rotor position is detected based on the position data and the energization pattern of the stator coil is sequentially switched based on the position data.
JP 59-127591 A JP-A-11-98883

  In relation to the switching of the energization pattern, Japanese Patent Application Laid-Open No. 59-127591 sets a time based on rotor position information based on an induced voltage during a non-energization period, and switches the energization pattern based on the passage of time. A method is disclosed, and Japanese Patent Laid-Open No. 11-98883 discloses an intersection of a value obtained by filtering digital data according to a voltage waveform (value of an induced voltage) and 1/2 of a measured voltage. Although the method of obtaining the switching timing of the energization pattern is disclosed based on the above, since any of the methods is easily affected by noise at the time of terminal voltage detection, it is possible to appropriately perform the desired energization pattern switching. difficult.

  The present invention has been made in view of the above circumstances, and is to provide a motor control device having high resistance to noise when a terminal voltage is detected.

  In order to achieve the above object, the present invention provides a motor control device that controls the rotation of a sensorless synchronous motor by sequentially switching energization patterns of a stator coil, and detects a terminal voltage of the stator coil every unit time. A detecting means; an induced voltage calculating means for calculating an induced voltage included in the terminal voltage; an induced voltage phase calculating means for calculating the phase of the induced voltage by calculation; and a motor rotational speed by calculating the amount of change of the induced voltage phase. Motor rotation speed calculating means to be obtained; energization pattern switching time calculating means for calculating a time until the energization pattern is switched from the induced voltage phase and the motor rotation speed; and an energization pattern when the energization pattern switching time is reached. And an energization pattern switching instruction means for instructing switching To.

  According to this motor control device, the terminal voltage of the stator coil is detected every unit time, the induced voltage included in the terminal voltage is obtained, the phase is obtained from the induced voltage, and the motor is calculated from the amount of change in the induced voltage phase. The sensorless synchronous motor is obtained from the rotation speed, and by obtaining the time until the energization pattern is switched from the induced voltage phase and the motor rotation speed, and switching the energization pattern when the energization pattern switching time is reached. Can be controlled.

  According to the present invention, the energization pattern switching time is obtained from the phase of the induced voltage included in the terminal voltage and the motor rotation speed based on the change amount of the phase, and when the energization pattern switching time is reached, the current energization pattern is obtained. Is switched to the next energization pattern, it is highly resistant to noise at the time of detecting the terminal voltage, whereby the desired energization pattern switching can be performed appropriately.

  The above object and other objects, structural features, and operational effects of the present invention will become apparent from the following description and the accompanying drawings.

  FIG. 1 is a block diagram of a motor control device showing an embodiment of the present invention.

  In the figure, 11 is a motor, 12 is an inverter, 13 is a DC power supply, 14 is a U-phase terminal voltage detector, 15 is a V-phase terminal voltage detector, 16 is a W-phase terminal voltage detector, 17 is an induced voltage An induced voltage phase calculation unit, 18 is a motor rotation speed calculation unit, 19 is an energization pattern switching time calculation unit, 20 is an output DUTY determination unit, 21 is a rotation speed instruction unit, and 22 is a PWM signal generation unit. Incidentally, the induced voltage / induced voltage phase calculation unit 17, the motor rotation speed calculation unit 18, the energization pattern switching time calculation unit 19, and the output DUTY determination unit 20 are configured by a microcomputer.

  The motor 11 includes a brushless DC motor including a stator including three-phase coils Uc, Vc, and Wc connected in a star shape with a neutral point N as a center, and a rotor including a permanent magnet. The motor 11 is rotationally driven by pseudo AC power input from the inverter unit 12 to the coils Uc, Vc, Wc.

  The inverter unit 12 includes a total of six switching elements Us, Vs, Ws, Xs, Ys, Zs (Us, Vs, Ws are upper phases, and Xs, Ys, Zs are lower phases) made of IGBTs or the like. A pair of Us and Xs, a pair of switching elements Vs and Ys, and a pair of switching elements Ws and Zs are respectively connected in parallel to a DC power source 13 formed of a battery or the like. The six switching elements Us, Vs, Ws, Xs, Ys, and Zs of the inverter unit 12 are driven on and off by the PWM signal input from the PWM signal generation unit 22 to convert the DC power into pseudo AC power and convert the motor 11. Are output to the coils Uc, Vc, and Wc.

  The U-phase terminal voltage detection unit 14, the V-phase terminal voltage detection unit 15 and the W-phase terminal voltage detection unit 16 are terminal voltages (U-phase terminal voltage Vu, V-phase terminal voltage) that appear in the coils Uc, Vc, Wc during motor rotation. Vv and W-phase terminal voltage Vw) are detected and AD converted, and terminal voltage information after AD conversion is output to the induced voltage / induced voltage phase calculation unit 17.

  The induced voltage / induced voltage phase calculation unit 17 is based on the terminal voltage information input from the U-phase terminal voltage detection unit 14, the V-phase voltage detection unit 15 and the W-phase voltage detection unit 16, respectively. , Vw (U-phase induced voltage Eu, V-phase induced voltage Ev and W-phase induced voltage Ew) are obtained by calculation, and the obtained U-phase induced voltage Eu, V-phase induced voltage Ev and W-phase are obtained. The phases of the induced voltage Ew (the U-phase induced voltage phase θeu, the V-phase induced voltage phase θev, and the W-phase induced voltage phase θew) are obtained by calculation and output to the motor rotation speed calculation unit 18 and the energization pattern switching time calculation unit 19, respectively. .

  The motor rotation speed calculation unit 18 calculates the motor rotation speed from the amount of phase change based on the induced voltage phase information input from the induced voltage / induced voltage phase calculation unit 17, and outputs with the energization pattern switching time calculation unit 19. The data is output to the DUTY determination unit 20.

  The energization pattern switching time calculator 19 switches the energization pattern based on the induced voltage phase information input from the induced voltage / induced voltage phase calculator 17 and the motor rotation speed information input from the motor rotation speed calculator 18. The time is calculated and output to the PWM signal generator 22.

  Based on the rotational speed information input from the rotational speed instruction unit 21 and the motor rotational speed information input from the motor rotational speed calculation unit 18, the output DUTY determination unit 20 performs a rotational speed instruction unit by known digital processing such as PI control. A DUTY signal is determined so that the motor 11 can obtain the rotation speed indicated in 21, and is output to the PWM signal generator 22.

  The PWM signal generation unit 22 is configured to switch each of the switching elements Us, Vs, Ws, Xs, Ys, based on the energization pattern switching time input from the energization pattern switching time calculation unit 19 and the DUTY signal input from the output DUTY determination unit 20. A PWM signal for turning on / off Zs is generated and output to the inverter unit 12.

  FIG. 2 is a basic timing chart in the case where the rotation of the motor 11 is controlled by rectangular wave driving with 120-degree conduction.

  The upper waveform in the figure schematically represents the energization state in each of the coils Uc, Vc, Wc. A current flows in each coil Uc, Vc, Wc in the positive direction (the direction from the coil toward the neutral point N) in a state where the upper phase switching elements Us, Vs, Ws are on, and the lower phase switching elements Xs, Ys. , Current flows in the negative direction (direction from the neutral point N toward the coil) in a state where Zs is on.

  The lower waveform in the figure schematically represents terminal voltages (U-phase terminal voltage Vu, V-phase terminal voltage Vv, and W-phase terminal voltage Vw) that appear in the coils Uc, Vc, Wc due to the energization. is there. The terminal voltages Vu, Vv, and Vw are in accordance with the energization, but are induced by the voltage at the neutral point N and the magnetic flux of the rotor magnet in each non-energization period, for example, 60 to 120 degrees in the U phase. The sum with the voltage appears.

  Further, 1 to 6 shown at the top in the drawing are symbols indicating energization patterns determined every 60 degrees of electrical angle, and the energization patterns 1 to 6 are sequentially repeated when the motor rotates. By the way, “switching the energization pattern” used in claims etc. means switching the current energization pattern to the next energization pattern, and “time until switching the energization pattern” is, for example, current It means the time until the energization pattern is switched to the next energization pattern.

  The energization pattern switching method realized when the motor 11 is operating according to the timing chart shown in FIG. 2 will be described below with reference to the flowcharts shown in FIGS.

  When the motor rotates, the terminal voltages (U-phase terminal voltage Vu, V-phase terminal) appearing in the coils Uc, Vc, Wc are detected by the U-phase terminal voltage detection unit 14, the V-phase terminal voltage detection unit 15, and the W-phase terminal voltage detection unit 16. The voltage Vv and the W-phase terminal voltage Vw) are detected every unit time, for example, every 10 μsec (step ST1 in FIG. 3).

  As shown in FIG. 2, the rotation of the motor 11 is controlled by a rectangular wave drive with 120 ° energization. Therefore, terminal voltage detection during the energization period, that is, for the U phase, in the energization patterns 1, 3, 4 and 6 The terminal voltage detection may be omitted for the V phase, the terminal voltage detection for the energization patterns 2, 3, 5, and 6 for the V phase, and the terminal voltage detection for 1, 2, 4, and 5 for the W phase. In this way, it is possible to reduce the burden on terminal voltage detection and arithmetic processing described later.

  Next, by the induced voltage / induced voltage phase calculation unit 17, the terminal voltages Vu, Vv, and Vv based on the terminal voltage information from the U-phase terminal voltage detection unit 14, the V-phase voltage detection unit 15, and the W-phase voltage detection unit 16 The induced voltages (U-phase induced voltage Eu, V-phase induced voltage Ev, and W-phase induced voltage Ew) included in Vw are obtained by calculation (step ST2 in FIG. 3).

  Specifically, in the U phase, the sum of the voltage at the neutral point N and the induced voltage due to the magnetic flux of the rotor magnet appears in the energization patterns 2 and 5 as the terminal voltage Vu, and in the V phase, the energization pattern. 1 and 4, the sum of the voltage at the neutral point N and the induced voltage due to the magnetic flux of the rotor magnet appears as the terminal voltage Vv. In the W phase, the voltage at the neutral point N and the rotor magnet in the energization patterns 3 and 6 The sum of the induced voltage and the induced voltage due to the magnetic flux appears as the terminal voltage Vw, and the voltage Vn at the neutral point N is (U-phase terminal voltage Vu + V-phase terminal voltage Vv + W-phase terminal voltage Vw) / 3. Therefore, the U-phase induced voltage Eu corresponds to the energization patterns 3 and 6 according to the equation Eu = Vu-Vn, and in the energization patterns 1 and 4, the V-phase induced voltage Ev corresponds to the energization patterns 3 and 6 according to the equation Ev = Vv-Vn. The W-phase induced voltage Ew is set to E = Respectively obtained by the equation of Vw-Vn.

  Next, the induced voltage / induced voltage phase calculating unit 17 calculates the phases θeu, θev, θew of the obtained U-phase induced voltage Eu, V-phase induced voltage Ev, and W-phase induced voltage Ew by calculation (FIG. 3). Step ST3).

Specifically, in the energization patterns 2 and 5, the U-phase induced voltage phase θeu is expressed by the equation θeu = tan ⁻¹ ((Ew−Ev) / Eu). The induced voltage phase θev is expressed by the following equation: θev = tan ⁻¹ ((Eu−Ew) / Ev). In the energization patterns 3 and 6, the W phase induced voltage phase θew is set to θew = tan ⁻¹ ((Ev−Eu) / Ew) respectively.

  Next, the motor rotation speed calculation unit 18 calculates the motor rotation speed ω from the phase change amount based on the induced voltage phase information from the induced voltage / induced voltage phase calculation unit 17 (step ST4 in FIG. 3).

  Specifically, the motor rotation speed ω is obtained from the energization time Δt of a certain pattern one time before by the equation ω = (1 / (Δt × 6)) × 2π.

  Next, the time until the energization pattern is switched by the energization pattern switching time calculation unit 19 based on the induced voltage phase information from the induced voltage / induced voltage phase calculation unit 17 and the motor rotation speed information from the motor rotation speed calculation unit 18. Is obtained by calculation (step ST5 in FIG. 3).

  Specifically, the motor 11 is rotated by repeating the energization patterns 1 to 6 every electrical angle of 60 degrees shown in FIG. 2, and the electrical angles are 0 degrees, 60 degrees, 120 degrees, 180 degrees, 240 degrees, Since 300 degrees and 360 degrees are the reference points for switching the energization pattern, here, the optimum time from the current electrical angle (induced voltage phase) to the electrical angle of the next switching point, that is, the present current Is determined by the following formula: energization pattern switching time = {(electric angle at the next switching point) − (current electrical angle)} / motor rotation speed.

  The time t1 in FIG. 2 will be described as an example. At time t1, the energization pattern 2 is being executed and the next switching point is 120 degrees. Therefore, here, the electrical angle (U-phase induced voltage phase θeu) at time t1 is used. ) And the motor rotation speed ω until the current energization pattern 2 is switched to the energization pattern 3 is obtained from the above equation.

  The energization pattern switching time can be calculated in any of the energization patterns 1 to 6, and since the calculation is repeated for each unit time described in step ST1, the energization pattern switching time obtained for each unit time. Is temporarily stored in the memory (step ST6 in FIG. 3).

  After obtaining the energization pattern switching time in this way, the energization pattern switching time calculation unit 19 sequentially determines whether or not the switching time has been reached, and when reached, a signal for switching is sent to the PWM signal generation unit. The PWM signal for switching to the next energization pattern is output from the PWM signal generation unit 22 to the inverter unit 12 (steps SS1 and SS2 in FIG. 4).

  As described above, since the energization pattern switching time is obtained every unit time, there are a plurality of timings at which the current energization pattern is switched to the next energization pattern. Therefore, after performing a filtering process such as averaging a plurality of calculation results to obtain a more optimal switching time, it is determined whether or not the switching time has been reached. Since the number of the plurality of calculation results increases / decreases depending on the motor rotation speed ω, the optimum switching time can be obtained by changing the filter constant used for the filter processing according to the motor rotation speed ω.

  Further, the motor rotation speed ω is recalculated based on the time interval for switching the energization pattern, and this motor rotation speed information is output to the output DUTY determination unit 20 (step SS3 in FIG. 4).

  Thus, according to the above-described motor control device, based on the phase (θeu, θev, θew) of the induced voltage (Eu, Ev, Ew) included in the terminal voltage (Vu, Vv, Vw) and the amount of change in the phase. The energization pattern switching time is obtained from the motor rotation speed (ω), and when the energization pattern switching time is reached, the current energization pattern is switched to the next energization pattern. The tolerance is high, so that the desired energization pattern switching can be performed properly.

  In addition, since the optimum energization pattern switching time is obtained by performing the filtering process on the energization pattern switching time obtained every unit time, the energization pattern switching can be performed more appropriately.

  FIG. 5 is a block diagram of a motor control device showing another embodiment of the present invention.

  This motor control device is different from the motor control device shown in FIG. 1 in that a current sensor 23 for detecting a motor current is provided, and a current detection unit 24 that AD converts a detection signal from the current sensor 23. The U-phase terminal for correcting the terminal voltage information output from the terminal voltage detectors 15, 16, 17 to the induced voltage / induced voltage phase calculator 17 based on the provided points and the motor current information from the current detector 24 The voltage correction unit 25, the V-phase terminal voltage correction unit 26, and the W-phase terminal voltage correction unit 27 are provided. Other configurations are the same as those of the motor control device shown in FIG.

  In the energization pattern switching method described above, the terminal voltage Vu in the energization patterns 2 and 5 is detected for the U phase, the terminal voltage Vv in the energization patterns 1 and 4 is detected for the V phase, and the energization pattern 3 is detected for the W phase. 6 is detected, but the phases θeu, θev, θew of the induced voltages Eu, Ev, Ew included in the detected terminal voltages Vu, Vv, Vw of each phase are very small. When affected by the multiplication value of motor current and coil resistance. Therefore, here, terminal voltage correction units 25, 26, and 27 are provided in order to eliminate the above-described influence so that appropriate terminal voltage information is input to the induced voltage / induced voltage phase calculation unit 17.

  In the above description, the energization pattern switching method in the case where the rotation of the motor 11 is controlled by the 120-degree energization rectangular wave drive is illustrated. However, if the rectangular wave drive has a non-energization period, an energization angle other than 120 degrees, In the case of 120 degrees <conduction angle <180 degrees, the same effect as described above can be obtained.

  In addition, the brushless DC motor has been described as an example of the motor 11, but the same effect as described above can be obtained even when another synchronous motor such as a reluctance motor is controlled.

  Furthermore, although the reference points for switching the energization pattern are exemplified as electrical angles of 0 degrees, 60 degrees, 120 degrees, 180 degrees, 240 degrees, 300 degrees, and 360 degrees, the motor rotation speed ω or the motor current For example, when the motor rotation speed ω is high, the switching point is set to −10 degrees, 50 degrees, 110 degrees, 170 degrees, and 230 degrees, which are electrical angles closer to the above. , 290 degrees and 350 degrees. Incidentally, when the switching point is changed by the motor current, the current detection means as shown in FIG. 5 may be employed to obtain the information.

  In the above-described energization pattern switching method, the induced voltage contained in the detected terminal voltage is obtained from the detected terminal voltage, and the phase thereof is further obtained. It is not necessarily optimal in arithmetic processing. This is because the reluctance torque of the motor has an effect, and in order to eliminate this effect, it is desirable to implement control that advances or delays the required induced voltage phase.

  6 shows a motor vector diagram during normal operation, and FIG. 7 shows a motor vector diagram when the induced voltage phase is advanced as compared with FIG. 6, where Va is a terminal voltage, Ea is an induced voltage, Ia Is the motor current, Ra is the coil resistance, and Ψa is the magnetic flux of the rotor magnet. As a method for advancing the induced voltage phase, in addition to a method in which a predetermined value is obtained by an experiment or the like, a formula using a motor constant or a motor constant of the same formula can be corrected by a motor current. A method of calculating the added value at any time using such an expression can be employed. A similar method can be adopted when the induced voltage phase is delayed.

It is a block diagram of a motor control device showing one embodiment of the present invention. It is a basic timing chart at the time of controlling the rotation of the motor shown in FIG. It is explanatory drawing of the electricity supply pattern switching method by the motor control apparatus shown in FIG. It is explanatory drawing of the electricity supply pattern switching method by the motor control apparatus shown in FIG. It is a block diagram of a motor control device showing other embodiments of the present invention. It is a motor vector figure at the time of normal driving | operation. FIG. 7 is a motor vector diagram when the induced voltage phase is advanced also from FIG. 6.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Motor, Uc ... U phase coil, Vc ... V phase coil, Wc ... W phase coil, N ... Neutral point, 12 ... Inverter part, Us, Vs, Ws ... Upper phase switching element, Xs, Ys, Zs ... Lower phase switching element, 13 ... DC power supply, 14 ... U phase terminal voltage detector, 15 ... V phase terminal voltage detector, 16 ... W phase terminal voltage detector, 17 ... induced voltage / induced voltage phase calculator, 18 ... Motor rotation speed calculation unit, 19 ... energization pattern switching time calculation unit, 20 ... output DUTY determination unit, 21 ... rotation speed instruction unit, 22 ... PWM signal generation unit, 23 ... current sensor, 24 ... current detection unit, 25 ... U Phase terminal voltage correction unit, 26... V phase terminal voltage correction unit, 27... W phase terminal voltage correction unit.

Claims (6)

A motor control device that controls rotation of a sensorless synchronous motor by sequentially switching energization patterns of a stator coil,
Terminal voltage detecting means for detecting the terminal voltage of the stator coil every unit time;
Induced voltage calculation means for calculating the induced voltage included in the terminal voltage by calculation;
Induced voltage phase calculating means for calculating the phase from the induced voltage by calculation;
Motor rotation speed calculation means for calculating the motor rotation speed from the amount of change in the induced voltage phase,
An energization pattern switching time calculating means for calculating a time until the energization pattern is switched from the induced voltage phase and the motor rotation speed;
An energization pattern switching instruction means for instructing switching of the energization pattern when the energization pattern switching time is reached;
The motor control apparatus characterized by the above-mentioned. The terminal voltage detection and the subsequent calculation processing are not performed in the energization period.
The motor control device according to claim 1. Further comprising means for filtering the energization pattern switching time obtained for each unit time,
The motor control device according to claim 1, wherein the motor control device is a motor control device. The filter constant used for the filtering process is changed according to the motor rotation speed.
The motor control device according to claim 3. The reference point for switching the energization pattern is changed by the motor rotation speed or the motor current.
The motor control device according to any one of claims 1 to 4, wherein: Means for correcting the induced voltage phase;
The motor control device according to claim 1, wherein the motor control device is a motor control device.

Images