JP5173209B2 - Drive device for a plurality of brushless motors connected in parallel, start method for a plurality of brushless motors connected in parallel, and rotor stop position detection method for a plurality of brushless motors connected in parallel - Google Patents

Description

  The present invention relates to a drive device, a start method, and a rotor stop position detection method for a plurality of brushless motors connected in parallel.

  A brushless motor of a type in which the rotor has a permanent magnet may perform drive control without a position sensor without providing a position sensor for detecting the rotational position of the rotor. In this case, the rotational position of the rotor is detected from the edge interval of the pulse signal obtained by inputting the induced voltage and the equivalent neutral point potential appearing at the motor terminal in the open section (non-energized phase) to the comparator. However, when the number of rotations is zero or when the number of rotations is extremely low, such as when a brushless motor is started, an induced voltage is not generated or is extremely small, so that a signal sufficient for detecting the rotation position cannot be obtained.

  As a conventional method for detecting the stop position of the rotor, the voltage applied to the three-phase coil is detected, the inductance of the coil is detected from the difference in the rise time of the voltage, and is opposed to the magnetic pole of the permanent magnet. The coil is judged (see Patent Document 1). When the direction of the magnetic flux by the coil and the direction of the magnetic flux of the iron core do not match, the impedance changes before and after the current is passed due to the residual magnetization of the iron core when the current is passed. Therefore, in the driving device disclosed in Patent Document 1, a current is continuously supplied twice or more in the same phase, and a coil having a minimum voltage rise time after the second time is detected.

  As another method for detecting the rotor stop position, a short pulse current that does not cause the rotor to move is simultaneously supplied from one coil to the other two coils to conduct three-phase energization. There is one that determines the rotor stop position by detecting the pulse width of the generated square wave pulse voltage (see, for example, Patent Document 2). Since the pulse widths of the two square wave pulse voltages generated simultaneously in the two coils slightly change depending on the difference in the rotor stop position, the rotor stop position is specified by comparing the two.

Also, as a conventional method for starting the brushless motor, the open pulse forced energization for forcibly switching the energization is performed without detecting the rotor position, and when the rotor position can be detected, the pulse signal described above is used. There is one in which the energization switching is controlled based on (see, for example, Patent Document 3).
In addition to this, the first energization pattern for positioning the rotor at a specific position is energized to suck the rotor position to the specific position to be in a locked state, and the second energization pattern advanced by 60 ° is energized for a short time. Thereafter, there is a method of starting the brushless motor by energizing a third energization pattern advanced by 60 ° from the second energization pattern (see, for example, Patent Document 4).

  Here, as a starting method in the case where the brushless motor rotates in reverse by an external load, for example, there is one disclosed in Patent Document 5. First, after the rotor rotation speed is reduced by three-phase energization, the energization is repeatedly turned ON / OFF during the three-phase energization, and the position and phase difference where the phase current becomes zero are examined. The direction of rotation is determined from the phase difference of the current, and when it is determined that the motor is in the reverse rotation state, the reverse rotation frequency is obtained from the zero point generation cycle of each phase. After pulling in by supplying an alternating current of reverse rotation frequency, the frequency is gradually changed from the reverse rotation direction to the frequency in the normal rotation direction, and the rotational speed of the rotor is increased to a desired rotational speed and started.

In general, a plurality of brushless motor control devices are prepared according to the number of brushless motors. However, when two brushless motors are operated synchronously, it is possible to perform sensorless driving by one control device as disclosed in Patent Document 6. In this control device, two DC brushless motors are connected in parallel to an inverter circuit, and energization control is performed based on a change in a combined voltage of induced voltages generated in a non-energized phase coil. The control device is provided with a capacitor connected to the voltage detection circuit so that the level rise at the time of power-on becomes slow. Since the voltage increase rate can be slowed according to the capacitance of the capacitor, the DC power supplied to the coils can be limited until the two brushless motors have the same rotation speed when the brushless motors are started. Thereby, the failure at the time of starting is suppressed.
JP 2004-40943 A JP 2002-335691 A Japanese Utility Model Publication No. 6-25224 JP 2001-211684 A JP 2001-128485 A Japanese Patent Laid-Open No. 11-235078

However, in the control device as disclosed in Patent Document 6, two brushless motors cannot be started with high torque. Furthermore, depending on the initial situation, there are cases where the rotation speeds of the two brushless motors cannot be made the same by changing the voltage according to the capacitance of the capacitor.
The present invention has been made in view of such circumstances, and a main object of the present invention is to start two brushless motors with high torque at high speed and stably by a simple method.

The invention according to claim 1 of the present invention for solving the above-mentioned problem is a drive device for synchronously driving a plurality of brushless motors connected in parallel, wherein the rotation speeds of the plurality of brushless motors include zero. When the forward / reverse rotational speed is in a small region, the rotational speed of the rotor is gradually increased by energizing each of the plurality of brushless motors for the initial energization time with an excitation pattern that matches the rotor stop position at the start. Energization pattern determining means for stopping the energization and free-running the rotors of the plurality of brushless motors, and induction generated in the brushless motors during the free-running of the plurality of brushless motors connected in parallel. Excitation switching timing calculating means for determining the excitation timing by detecting the rotor position from the voltage synthesized signal; And a plurality of brushless motor driving device connected in parallel, characterized in that it has.
In order to correctly detect the rotational position of the rotor when it is started, the plurality of brushless motor driving devices connected in parallel are put into a free-run state after being accelerated, and the rotor position is determined from the induced voltage generated during the free-run. Is detected. Since the induced voltage at this time is not affected by the pulse width modulation signal or the like, the rotor position is correctly detected. After detecting the rotor position, normal energization switching is performed.

The invention according to claim 2 is the drive device for the plurality of brushless motors connected in parallel according to claim 1, wherein the initial energization time is from the start of rotation of the rotor to the first energization switching timing. It is characterized by having a length of less than time.
In this brushless motor drive device, acceleration is performed within a range in which the rotor is not attracted to the stator and reverse torque is generated, so that the free-running can be performed at a rotational speed sufficient to detect the rotor position.

According to a third aspect of the present invention, in the drive device for a plurality of brushless motors connected in parallel according to the first or second aspect, the excitation switching timing calculation means is generated after the second time during a free run. The excitation timing is calculated from a time interval of a signal obtained by synthesizing the induced voltage.
In this plurality of brushless motor drive devices connected in parallel, the signal generated for the first time when free-running may be a square-wave pulse voltage due to the energy accumulated in the coil. The detection accuracy is improved by using the second and subsequent signals without using them.

According to a fourth aspect of the present invention, in the drive device for a plurality of brushless motors connected in parallel according to any one of the first to third aspects, the excitation capable of driving the plurality of brushless motors synchronously. A plurality of patterns are selected, and excitation voltage output means for energizing each excitation pattern sequentially in a time range in which the rotor does not rotate, and a square wave generated in each coil of the plurality of brushless motors when the excitation pattern is switched A square wave pulse voltage width detecting means for detecting a pulse width of a signal obtained by synthesizing the pulse voltage, and obtaining a minimum value or a maximum value from a pulse width of the signal obtained by synthesizing the square wave pulse voltage in a plurality of excitation patterns, Rotor position estimating means for determining the stop position of the rotor from the excitation pattern having the maximum value, and the determination by the rotor position estimating means Characterized by being configured to output a predetermined by an electrical angle retard or advance the cause energization pattern from the stop position of the rotor as a start-up excitation pattern.
In the plurality of brushless motor driving devices connected in parallel, a square wave pulse voltage is generated in each brushless motor when the excitation pattern is switched. The pulse width of a signal obtained by synthesizing this square wave pulse voltage for all brushless motors is examined for each of a plurality of types of excitation patterns, and the stop position of the rotor is specified by the maximum value or the minimum value. Since the excitation pattern for starting according to the stop position of the rotor is predetermined, the brushless motor is started with the excitation pattern.

According to a fifth aspect of the present invention, in the drive device for a plurality of brushless motors connected in parallel according to the fourth aspect, the excitation voltage output means includes an excitation pattern for magnetizing the N-pole coil and the same coil as the S-pole. An excitation pattern for making the coil non-energized is implemented between magnetized excitation patterns.
This plurality of brushless motor drive devices connected in parallel eliminates the residual magnetization of the coil by magnetizing a coil of a certain phase and then turning it off before the coil is magnetized to the south pole. Is done. Even when the S-pole magnetization is changed to the N-pole magnetization, the non-energized state is established during that time, so that the residual magnetization of the coil is eliminated.

The invention according to claim 6 is the drive device for the plurality of brushless motors connected in parallel according to claim 4 or claim 5, wherein the rotor position estimation means has a minimum pulse width of the signal obtained by synthesizing the square wave pulse voltage. When the rotor stop position is determined from the value, an excitation pattern with a 120 ° phase delay is output during forward rotation, and an excitation pattern with a 120 ° phase advance is output during reverse rotation.
The plurality of brushless motor drive devices connected in parallel can obtain sufficient torque to start rotation of the rotor when the excitation pattern having a phase difference of 120 ° with respect to the rotor stop position is selected. Immediately after that, a rotational characteristic such that the torque increases can be obtained. For this reason, a rotor can be started stably and a big acceleration can be obtained.

According to a seventh aspect of the present invention, in the drive device for a plurality of brushless motors connected in parallel according to any one of the fourth to sixth aspects, a square generated in each coil of the plurality of brushless motors. A voltage dividing circuit for dividing a signal obtained by synthesizing the wave pulse voltage and inputting the divided signal to the square wave pulse voltage width detecting means is provided.
The plurality of brushless motor driving devices connected in parallel can perform signal processing by setting a desired voltage level in the voltage dividing circuit when a signal obtained by synthesizing the square wave pulse voltage is high.

According to an eighth aspect of the present invention, in the drive device for the plurality of brushless motors connected in parallel according to any one of the fourth to seventh aspects, the rotation of the rotor of each of the plurality of brushless motors is performed. When the reverse rotation is performed synchronously, a low duty voltage is applied, the brake is applied to the rotor, and then the excitation voltage output means is operated.
The plurality of brushless motor driving devices connected in parallel can perform signal processing by setting a desired voltage level in the voltage dividing circuit when a signal obtained by synthesizing the square wave pulse voltage is high.

The invention according to claim 9 is the drive device for a plurality of brushless motors connected in parallel according to any one of claims 4 to 8, wherein the rotation of each rotor of the plurality of brushless motors is performed. When not synchronized, a low-duty voltage is applied, the brake is applied to the rotor, and then the excitation voltage output means is operated.
The plurality of brushless motor driving devices connected in parallel are configured such that when the plurality of rotors are rotating asynchronously, the respective rotors are braked to be stopped or almost stopped, and then the rotor is stopped. Detect position. Start processing is performed based on the detected stop position.

According to a tenth aspect of the present invention, in the drive device for the plurality of brushless motors connected in parallel according to the eighth or ninth aspect, the means for detecting the voltage of the motor terminal of each phase of the plurality of brushless motors. A filter for removing noise contained in the detection signal of the motor voltage is provided, and a filter delay phase correcting means for correcting the delay phase of the filter that changes according to the rotational speed of the brushless motor is provided in the excitation switching timing calculating means. Features.
The plurality of brushless motor driving devices connected in parallel correct the excitation pattern switching timing in consideration of the phase delay due to the filter so that the phase switching can be performed at an appropriate timing.

The invention according to claim 11 is the drive device for a plurality of brushless motors connected in parallel according to claim 10, wherein the filter removes noise generated when the brushless motor is subjected to pulse width modulation control. It is a next CR filter.
Since the filter in the drive device of the plurality of brushless motors connected in parallel has a characteristic of removing high frequency component noise in the pulse width modulation control, a phase delay is likely to occur when the rotational speed of the brushless motor is high. The filter delay phase correction means corrects such a phase delay.

According to a twelfth aspect of the present invention, in the drive device for a plurality of brushless motors connected in parallel according to the eleventh aspect, the excitation switching timing calculation means corrects a lag phase caused by a circuit other than the filter. It further has a correction means.
The plurality of brushless motor driving devices connected in parallel have a function of correcting a lagging phase inherent to the device that occurs regardless of the rotational speed.

The invention according to claim 13 is a starting method for synchronously starting a plurality of brushless motors connected in parallel, and when the rotational speed of the rotor is in a region including zero and the forward / reverse rotational speed is small, the stop position After energizing the plurality of brushless motors for an initial energization time with the excitation pattern matched to the rotation speed of the rotor gradually increasing , the energization is stopped and the rotors of the plurality of brushless motors are free-running. A step of detecting a rotor position from a signal obtained by synthesizing an induced voltage generated in each of the brushless motors during free run of the plurality of brushless motors connected in parallel, and excitation based on the detected rotor positions A plurality of brushless motors connected in parallel, characterized by having a step of switching patterns It was the starting method.
In this method of driving a plurality of brushless motors connected in parallel, when a plurality of rotors starts rotating, energization is stopped and a free-run state is set. The position of the rotating rotor is detected from the induced voltage generated at this time. Thereafter, normal energization switching is performed based on the detected rotor position to control the drive of the brushless motor.

According to a fourteenth aspect of the present invention, in the start method for the plurality of brushless motors connected in parallel according to the thirteenth aspect, the initial energization time is from the start of rotation of the rotor to the first energization switching timing. The step of detecting the rotor position, which is less than the length of time, is performed until the fourth signal generated by combining the induced voltages generated in each of the plurality of brushless motors when the rotor is rotated. It is characterized by that.
In this method of starting a plurality of brushless motors connected in parallel, at the time of start-up, acceleration is performed until the time corresponding to the first energization switching timing, free run is performed, and the rotor is processed until the time corresponding to the fourth energization switching timing. The position of is detected.

The invention according to claim 15 includes a rotor and a stator having permanent magnets connected in parallel, and a plurality of brushless motors in which three-phase coils are wound in order in the circumferential direction in synchronization with the stator. A plurality of driveable excitation patterns are selected, and the residual magnetization of the coil is between the excitation pattern that magnetizes the N-pole of a phase coil of the plurality of brushless motors and the excitation pattern that magnetizes the same coil as the S-pole. The energization order is selected so that the excitation patterns that are not energized are energized so as to be eliminated, and each excitation pattern is energized in turn in a time range in which the rotor does not rotate, and the excitation patterns are switched. A parallel arrangement characterized in that a stop position of the rotor is determined from a minimum value of a pulse width of a signal obtained by synthesizing a square wave pulse voltage generated in each brushless motor. It was connected rotor stop position detection method of a plurality of brushless motors.
In this method of detecting the rotor stop positions of a plurality of brushless motors connected in parallel, after a certain phase coil is N pole magnetized, the coil remains in the non-energized state before the coil is S pole magnetized. Magnetization is eliminated. Even when the magnetization is changed from the S-pole magnetization to the N-pole magnetization, the non-energized state is established during that time, so that the residual magnetization of the coil is eliminated and the detection accuracy of the rotor stop position is improved.

The invention according to claim 16 includes a rotor and a stator having permanent magnets connected in parallel, and a plurality of brushless motors in which three-phase coils are wound in order in the circumferential direction in synchronization with the stator. When starting, select a plurality of excitation patterns that can drive the plurality of brushless motors, energize each excitation pattern sequentially in a time range in which the rotor does not rotate, and switch the excitation patterns, the plurality of brushless motors Check the pulse width of the combined signal of the square-wave pulse voltages generated in each, determine the rotor stop position from the minimum value, and at the time of forward rotation, sufficient torque is obtained for the rotor to start rotation, and immediately after startup torque is increased, sufficient bets to output the excitation pattern obtained by delaying the 120 ° phase from the stop position, the rotor is in the reverse rotation start rotating Click is obtained and the torque is increased immediately after starting, in parallel, characterized in that the free-run state and stops energizing the outputs excitation pattern is advanced to 120 ° phase from the stop position all phases A method of starting a plurality of connected brushless motors was used.
In the starting method of the plurality of brushless motors connected in parallel, by selecting an excitation pattern having a phase difference of 120 ° with respect to the rotor stop position, sufficient torque is obtained for the rotor to start rotating, In addition, the torque can be increased immediately after the rotation. For this reason, a brushless motor can be started reliably.

The invention according to claim 17 is a starting method for synchronously starting a plurality of brushless motors connected in parallel, having a rotor having a permanent magnet and a stator, and a three-phase coil in the circumferential direction. Detecting a stop position of the rotor by obtaining a signal obtained by combining the inductances generated in the coils of the plurality of brushless motors wound in order, and a torque sufficient for the rotor to start rotating. After the excitation pattern with a 120 ° phase delay from the stop position is output for a certain period of time and the torque increases immediately after startup, the step of stopping energization of all phases and the state where energization of all phases is stopped When the rotor position can be detected by the induced voltage, the step of controlling energization based on the detected rotor position and the induced voltage in the state where the energization of all phases is stopped. If the rotor position detection is impossible that has the steps of energizing the excitation pattern to stop the rotation of each of said rotors of said plurality of brushless motors at low duty, 2 to stop the rotation of said rotor After performing the phase energization lock process, the step of detecting the stop position of the rotor by using the inductance of the coil is performed, and a method for starting a plurality of brushless motors connected in parallel is provided.
In the starting method for a plurality of brushless motors connected in parallel, if the rotor position can be detected when starting control is performed so as to cause the brushless motor to normally rotate, the routine proceeds to normal rotation control as it is. On the other hand, if the rotor position cannot be detected, it is determined that the rotor is in the reverse rotation state or the asynchronous operation state, the brake is applied to the rotor, and the control at the start is performed again.

According to the present invention, it is possible to detect an induced voltage generated at the motor terminals without being affected, such as pulse width modulation signal to produce a free-running state during startup. This makes it possible to correctly detect the rotor position without being affected by disturbance. Further, since the rotor position is detected during free running, it is possible to detect the rotor position in a short time and shift to normal operation.
When it is determined that a plurality of brushless motors are not rotating in the forward direction synchronously at the start, after performing energization control to stop the respective rotors and performing the start process again, the reverse rotation state or Even in an asynchronous operation state, it can be quickly started in the forward direction. This eliminates the need for complicated processing for determining the reverse direction.
When a plurality of brushless motors connected in parallel are synchronously driven without a sensor, the system can be reliably started regardless of the rotation state at the time of starting, and a highly reliable system can be obtained.

  The best mode for carrying out the invention will be described in detail with reference to the drawings. Note that the same reference numerals are given to the same components in each embodiment. Moreover, the description which overlaps between embodiment is abbreviate | omitted.

(First embodiment)
As shown in FIG. 1, the brushless motor system includes two brushless motors 1A and 1B and a drive device 2 that controls the rotational drive of the brushless motors 1A and 1B.
The brushless motor 1A has a rotor having a permanent magnet and a stator, and three-phase (U, V, W) coils U ₁ , V ₁ , W ₁ are wound around the stator in order in the circumferential direction. Similarly, the brushless motor 1B has a rotor having a permanent magnet and a stator, and three-phase (U, V, W) coils U ₂ , V ₂ , W ₂ are wound around the stator in order in the circumferential direction. ing. These two brushless motors 1 </ b> A and 1 </ b> B are connected in parallel to the driving device 2. Hereinafter, the two brushless motors 1A and 1B connected in parallel may be collectively referred to as a plurality of parallel motors 1. This brushless motor system is a sensorless type system that does not have a sensor for detecting the rotor position.

  The driving device 2 includes a control device 11 configured by a microcomputer, an induced voltage I / F (interface) circuit 12 that detects voltages of three-phase U, V, and W motor terminals of the plurality of parallel motors 1, and energization An inverter 13 having a switching element for switching, and a voltage dividing circuit 14 that is a level conversion circuit that converts the level of the voltage applied to the three-phase U, V, and W motor terminals of the parallel motor 1. Between the control device 11 and the inverter 13, predrivers 37A and 37B, an overcurrent detection circuit 38, and overcurrent protection means 39 are provided. In the plural parallel motor 1, since two brushless motors 1A and 1B are connected in parallel, the voltage at the motor terminal is equal to the voltage generated at the motor terminal of each brushless motor 1A and 1B.

  As shown in FIG. 2, the induced voltage I / F circuit 12 receives the voltages (analog signals) of the motor terminals of the three phases U, V, and W, and divides them into voltages that can be input to the comparators 17A to 17C. Low-pass filter circuits 15A, 15B and 15C composed of a voltage dividing circuit (resistor R11 and resistor R12) and a primary CR filter (resistor R11 and capacitor C11) for removing noise of the pulse width modulation signal, and an equivalent neutral point potential A chattering component is generated from the output of the comparators 17A, 17B, and 17C, and the comparators 17A to 17C that generate a pulse signal from the analog signal of the induced voltage appearing in the circuit 16 to detect, the equivalent neutral point potential and the non-energized phase (open period). And low-pass filters (primary CR filters) 18A, 18B, and 18C for cutting.

Here, the circuit 16 that detects the equivalent neutral point potential employs a two-phase comparison method that detects the equivalent neutral point potential from the motor terminal voltages of the V phase and the W phase for the U phase, for example. ing. In this way, a substantially flat voltage is obtained as the equivalent neutral point potential. It should be noted that a three-phase comparison method for obtaining an equivalent neutral point potential using all three-phase signals of U, V, and W may be employed. In this case, the potential at the equivalent neutral point is a substantially triangular wave centered at 1/2 of the power supply voltage.
The comparators 17A to 17C output a low level signal when the induced voltage analog signal is higher than the equivalent neutral point potential, and output a high level signal when the induced voltage analog signal is lower than the equivalent neutral point potential. A pulse signal is generated. In each of the comparators 17A to 17C, a pulse signal having a resolution of 120 electrical degrees is created. These signals are respectively input to the composite signal generation circuit 19 through the low-pass filter circuits 18A to 18C.

  As shown in FIG. 3, the inverter 13 is a circuit configured by connecting six switching elements 40UH, 40UL, 40VH, 40VL, 40WH, and 40WL two by two between the positive and negative terminals of the power supply 20. The DC voltage supplied from the power supply 20 is converted into an AC voltage based on a pulse width modulation signal (drive signal) input from the control device 11 and applied to each phase U, V, W of the plural parallel motors 1. Each of the switching elements 40UH to 40WL has two FETs (Field effect transistors) connected in parallel. The reason why the two FETs are connected in parallel is that a plurality of parallel motors 1 have two brushless motors 1A and 1B connected in parallel, so that the current value is 2 as compared with the case where there is only one brushless motor. Because it doubles.

  Two shunt resistors 13A and 13B are provided in parallel between the inverter 13 and the ground level. The shunt resistors 13A and 13B have the same resistance value, and the current flowing through the inverter 13 using these shunt resistors 13A and 13B, that is, the current input to the brushless motors 1A and 1B is detected using the overcurrent detection circuit 38. It can be detected. Instead of connecting the two shunt resistors 13A and 13B in parallel, one resistor can be substituted, but by connecting the two resistors in parallel, the same resistance as the shunt resistor of the inverter circuit for one brushless motor Can be used.

  As shown in FIG. 1, the voltage dividing circuit 14 divides a terminal voltage (for example, 12 V, 36 V, etc.) generated at the three-phase U, V, W motor terminals of the plurality of parallel motors 1 by two resistors, This is a circuit that makes the voltage level (for example, 3V, 5V, etc.) usable in the control device 11.

  The control device 11 includes a separation unit 21 connected to the induced voltage I / F circuit 12, an excitation switching timing calculation unit 22, a rotation direction determination unit 23, a rotation direction detection logic selection unit 24, and a brake stop unit 25. , Energization pattern determination means 26, excitation voltage output means 27, and PWM duty determination means 28. The control device 11 is connected to the voltage dividing circuit 14 and includes a square wave pulse voltage width detection means 29, a square wave pulse voltage width comparison means 30, and a rotor position estimation means 31 that are used at the time of starting. Furthermore, it has an overcurrent protection means 32 connected to the overcurrent detection circuit 38.

The separation means 21 performs processing for separating the edge of the pulse signal input from the induced voltage I / F circuit 12 into an edge of the induced voltage and an edge of the square wave pulse voltage. The excitation switching timing calculation means 22 generates one pulse signal with a resolution of 60 ° electrical angle from three pulse signals with a resolution of 120 ° electrical angle in order to calculate the excitation phase according to the induced voltage edge, and switches the excitation switching. Calculate timing. The excitation switching timing calculation means 22 is provided with a delay phase correction unit 22A that corrects the excitation switching timing.
The rotation direction determination unit 23 determines the rotation direction from the excitation switching timing, and outputs a predetermined command to the rotation direction detection logic selection unit 24 and the brake stop unit 25. The rotation direction detection logic selection unit 24 is used when the logic used by the separation unit 21 can be selected depending on the rotation direction of the brushless motors 1A and 1B. The brake stop means 25 is used when energizing an energization pattern that stops the brushless motors 1A and 1B.

  The energization pattern determination unit 26 includes a steady-state excitation unit 33, a stop position detection unit 34, a free-run control unit 35, and a start-up excitation unit 36. The constant excitation means 33 determines an excitation pattern according to the rotor position at the excitation switching timing calculated by the excitation switching timing calculation means 22 when the brushless motors 1A and 1B rotate in synchronization. The stop position detecting means 34 receives a start command from the outside and causes the excitation voltage output means 27 to generate a pulse width modulation signal for detecting the rotor stop position. The starting excitation means 36 determines an excitation pattern corresponding to the rotor stop position corresponding to the square-wave pulse voltage width determined to be the minimum by the rotor position estimation means 31. The free-run control means 35 performs a process of detecting the rotor position by energizing the brushless motors 1A and 1B after energizing the starting excitation pattern for a predetermined initial energization time Ts1. Details of these processes will be described later.

  The excitation voltage output means 27 outputs a signal for applying an excitation current to the coils of the brushless motors 1A and 1B to the pre-drivers 37A and 36B. The Hi-side pre-driver 37A is a driver that switches ON / OFF of the high-potential side switching element at the duty ratio determined by the PWM duty determining means 28. The Lo-side pre-driver 37B is a driver that switches ON / OFF of the switching element on the low potential side. The Hi-side pre-driver 37A has a function of turning off each switching element when a signal is input from the overcurrent protection means 39 when an overcurrent flows through the inverter 13. When an overcurrent is detected, a signal is input to the overcurrent protection means 32 and a software reset is applied.

  The square wave pulse voltage width detection unit 29 performs a process of detecting the square wave pulse voltage width from the signal input from the voltage dividing circuit 14. The square wave pulse voltage width detection means 29 has a storage means 29A such as a memory, and can store the detected square wave pulse voltage width data in association with the excitation pattern at that time. The square wave pulse voltage width comparison means 30 compares data of a plurality of square wave pulse voltage widths stored in the storage means 29A of the square wave pulse voltage width detection means 29 and determines the smallest one. The rotor position estimation means 31 estimates the rotor position at a stop or at a low speed based on the comparison result of the square wave pulse voltage width.

  As shown in FIG. 3, the overcurrent detection circuit has a low-pass filter composed of a resistor and a capacitor, and the voltage value after removing noise is input to the comparator. A preset reference voltage is input to the comparator. When an overcurrent flows through the inverter circuit 13, the voltage value input to the comparator becomes higher than the reference voltage, and the comparator outputs a low level signal. This signal is input from the interrupt port of the control device 11 to the overcurrent protection means 32 and causes a software reset to be executed. Further, when the voltage at the output terminal of the comparator falls to a low level, a current flows through a diode provided as hardware overcurrent protection means 39, and the output signal from the PWM duty determination means 28 is output as a Hi-side predriver 37A. Will not be entered.

Next, the operation of the drive device 2 will be described.
When the plural parallel motors 1 are started, there are a case where each brushless motor 1A, 1B is stopped and a case where each brushless motor 1A, 1B is rotated by an external load. Furthermore, when each brushless motor 1A, 1B is rotated, there are a case where the brushless motor 1A, 1B is rotating forward and a case where it is rotating backward. For example, when a plurality of parallel motors 1 are used for a radiator fan rotation mechanism, when wind is blowing in the direction from the radiator toward the engine room, each brushless motor 1A, 1B is rotated forward. On the other hand, when each brushless motor 1A, 1B is rotating in the reverse direction, when the wind is blowing in the direction of the radiator from the engine side, or when negative pressure is generated in the reverse direction with respect to the radiator fan. Can be considered.

  When it is assumed that the drive device 2 is used as a radiator fan, the radiator fan has a structure that easily rotates in the forward rotation direction, and a large wind force is required to rotate in the reverse rotation direction. However, there is little possibility that large wind power is generated in the reverse direction from the structure of the vehicle, and even when the radiator fan rotates in reverse, the rotation speed is considered to be low. Therefore, in this drive device 2, even when each brushless motor 1A, 1B rotates in reverse with an external load, control at the time of starting is performed on the assumption that the rotation speed and torque are small.

FIG. 4 schematically shows a classification of the starting method according to the rotational speeds of the brushless motors 1A and 1B of the plural parallel motors 1 at the time of starting. When the rotations of the brushless motors 1A and 1B are synchronized with each other, they are divided into a case where they are asynchronous and when they are further synchronized, three cases are divided according to the rotation speed.
If the rotations of the brushless motors 1A and 1B shown on the horizontal axis are synchronized and the respective rotation speeds include a region R1 that includes zero, the driving device 2 executes a start start process based on inductance detection.
If the rotations of the two brushless motors 1A and 1B are synchronized and their rotational speeds are in the region R2 larger than the region R1 in the positive rotation direction, the rotor position is detected by detecting the induced voltage and the rotation is controlled. . When the rotational speed is in the region R3 larger than the region R1 in the reverse rotation direction, the process proceeds to the region R1 by the reverse rotation state determination process and the rotor stop process, and the start start process by inductance detection is executed. The region R1 and the region R2 overlap each other at a rotation speed near N1 (rpm). The rotational speed N1 corresponds to a low rotational speed at which the rotor position cannot be detected by detecting the induced voltage. If the rotational speed is zero or low, the rotor position can be detected with a resolution of an electrical angle of 60 ° by inductance detection, and energization can be performed at a phase that can generate the maximum torque in the forward rotation direction. On the other hand, as the rotational speed increases, the detection result of the rotor position by inductance detection is out of phase from the electrical angle of 60 ° and the detection accuracy becomes worse, so the starting torque decreases compared to the stopped state. Because.

If the rotations of the two brushless motors 1A and 1B are synchronized and the rotation speeds of the two brushless motors 1A and 1B are in the region R3 larger than the region R1 in the reverse rotation direction, the brushless motors 1A and 1B are braked as described later. The rotor position is detected after shifting to the region R1. The region R1 and the region R3 overlap with each other when the rotation speed is near -N1 (rpm).
If the rotations of the two brushless motors 1A and 1B are asynchronous, the brushless motors 1A and 1B are braked and synchronized in all regions R4 without depending on the rotation speed.
Note that the region R1 and the region R2 may be divided with the rotation speed N1 as a boundary without overlapping. The region R1 and the region R3 may be divided with the rotation speed −N1 as a boundary without overlapping.

  The driving device 2 first executes processing assuming that the rotational speeds of the brushless motors 1A and 1B are in the region R1, and shifts to steady driving through processing corresponding to the region R2. If the rotor position cannot be detected when the processing corresponding to the region R2 is performed, the rotation state of the brushless motors 1A and 1B is regarded as being in the region R3 or the region R4, and the processing corresponding to the region R3 or the region R4 is started. Try again. Since the same processing can be used for the processing in the region R3 and the processing in the region R4, the processing for distinguishing the region R3 from the region R4 is not performed. A specific example of such a starting method will be described with reference to the flowchart of FIG.

When a start start command is input to the stop position detection means 34, overcurrent detection is performed (step S101). The overcurrent is monitored by the current value flowing through the shunt resistors 13A and 13B of the inverter 13. When the current flowing through the shunt resistors 13A and 13B exceeds a predetermined value, it is determined that the current is an overcurrent, that is, an overload state (Yes in step S101), and all phases are turned off and a stop process is performed (step S102). The process is terminated. If no overcurrent is detected (No in step S101), the combined inductance of the plurality of parallel motors 1 is detected, and rotor position detection processing is performed (step S103). In the two parallel motors of the same standard, two coils having the same characteristics are connected in parallel, so the combined inductance and combined resistance of the coils are halved. In this state, electric power is accumulated in the coil, and the time that the electric power is consumed by the flywheel current is detected by the square wave pulse voltage width. If the rotor position with respect to each motor coil is the same (synchronized state), the rotor position can be specified from the square-wave pulse voltage width.
The overcurrent check is constantly monitored by another program that is processed in parallel. If an overcurrent is detected during the processing after step S103, the processing is stopped at that point.

Assuming that the two brushless motors 1A and 1B are synchronized, the control device 11 detects the rotor stop position from the data obtained by the combined inductance detection. Then, the starting excitation means 36 determines a starting excitation pattern having a phase capable of generating the maximum torque with respect to the rotor position, and the excitation voltage output means 27 outputs the starting excitation pattern (step S104). The initial energization counter is activated, and the aforementioned phase is energized until a preset initial energization time Ts1 elapses (step S105). When the initial energization time Ts1 elapses (Yes in step S105), the free-run control means 35 turns off the energization of all phases and free-runs (step S106). From the induced voltage generated while the respective rotors of the brushless motors 1A and 1B are free running due to inertia, the rotor position is detected using the forward rotation exclusive logic (step S107). The rotor position at this time is a position when it is assumed that the two brushless motors 1A and 1B are synchronized. Once you detect the number of times that defines the rotor position previously (in step S108 Yes), the process proceeds to sensorless driving by the induced voltage with steady-state excitation means 33 (steady driving mode) (step S109).
If the rotor position cannot be detected a predetermined number of times (No in step S108), the process waits until the number of times for measuring the edge interval of the induced voltage elapses (step S110). When the number of times has elapsed (Yes in step S110), the rotation direction determination means 23 determines that the brushless motors 1A and 1B are rotating in reverse or asynchronous. In this case, as a brake process by the brake stop means 25, a two-phase energization lock process is performed with a low duty (step S111). The brake process is performed for a predetermined time, and when this time has elapsed (step S112), the process returns to step S101.

Here, Step S103 to Step S105 are processes when the initial rotational speed is within the range of the region R1 and the region is accelerated from here to the region R2.
Details of step S103 will be described. Here, when the direction of the magnetic flux generated by the coil is the same as the direction of the magnetic flux of the magnet, the stop position is determined by focusing on the fact that the permeability of the magnet core increases and the inductance decreases.

  When starting the two brushless motors 1 </ b> A and 1 </ b> B in a stopped state, a start command is input to the stop position detecting means 34 of the control device 11 from the outside. The stop position detection means 34 issues a command to the excitation voltage output means 27 so that six predetermined excitation patterns for stop position determination are continued for a period of time that the rotor does not rotate. The time that the rotor does not rotate varies depending on the inertia of the brushless motors 1A and 1B, but is, for example, between several microseconds and several milliseconds, and is counted by a counter included in the control device 11. The excitation voltage output means 27 outputs a pulse width modulation signal corresponding to the excitation pattern to the inverter 13, and the switching elements 40UH to 40WL are turned on and off in response to the pulse width modulation signal, so that any one of the three phases is selected. Energized.

Here, FIG. 6 shows an excitation pattern for determining the stop position instructed by the stop position detecting means 34. These excitation patterns # 1 to # 6 are patterns that can drive the brushless motors 1A and 1B, and show the case where the relative positions of the coils and the rotors of the brushless motors 1A and 1B are the same (synchronous). ing. On the contrary, when the relative positions of the coils and the rotors of the brushless motors 1A and 1B are not the same (asynchronous), the following synthetic inductance detection method is not established, and thus a synchronization process is necessary.
In excitation pattern # 1, current flows from U-phase coils U ₁ and U ₂ (hereinafter simply referred to as U-phase) to V-phase coils V ₁ and V ₂ (hereinafter referred to as V-phase). The U phase is N pole magnetized and the V phase is S pole magnetized. When the arrangement of the U, V, and W phases and the stop position of the rotor 41 are as shown in the figure, as shown by the arrows, the U-phase passes through the S pole and N pole of the permanent magnet 42 of the rotor 41 in order, A magnetic flux toward the V phase is formed.
In the excitation pattern # 2, a current flows from the U phase to the W phase coils W ₁ and W ₂ (hereinafter simply referred to as the W phase). The U phase is N pole magnetized and the W phase is S pole magnetized. As indicated by the arrow, a magnetic flux is formed from the U phase through the S pole and the N pole of the permanent magnet of the rotor 41 in that order toward the W phase.
In excitation pattern # 3, a current flows from the V phase to the W phase. The V phase is N pole magnetized and the W phase is S pole magnetized. As indicated by the arrow, a magnetic flux is formed from the V-phase to the S-phase and N-pole of the permanent magnet of the rotor 41 in that order and toward the W-phase.
In excitation pattern # 4, a current flows from the V phase to the U phase. The V phase is N pole magnetized and the U phase is S pole magnetized. As indicated by the arrow, a magnetic flux is formed from the V phase through the S pole and the N pole of the permanent magnet of the rotor 41 in that order and toward the U phase.
In excitation pattern # 5, a current flows from the W phase to the U phase. The W phase is N pole magnetized and the U phase is S pole magnetized. As indicated by the arrow, a magnetic flux is formed from the W phase through the S pole and the N pole of the permanent magnet of the rotor 41 in that order toward the U phase.
In excitation pattern # 6, a current flows from the W phase to the V phase. The W phase is N pole magnetized and the V phase is S pole magnetized. As indicated by the arrow, a magnetic flux is formed from the W phase through the S pole and the N pole of the permanent magnet of the rotor 41 in this order and toward the V phase.

As shown in FIG. 7, the stop position inspection of the rotor 41 in this embodiment performs energization control with steps 0 to 11 as one set. Each step is incremented every time the value of the counter in the control device 11 reaches a predetermined value. When incrementing a step, the counter is reset each time.
In step 0, the excitation pattern # 1 is selected and energization is performed with the duty of the pulse width modulation signal being 100%. The remaining W phase is released. In step 1, the duty is set to 0% and neither phase is energized. When Step 0 ends and the process proceeds to Step 1, the electrical energy stored in the coil at the moment when the switching elements 40UH to 40WL of the inverter 13 are turned off is converted into a current via the return diode of the switching elements 40UH to 40WL. Flowing. At this time, a square wave pulse voltage is generated at the V-phase motor terminal. This terminal voltage is taken as a square wave pulse voltage into the voltage dividing circuit 14 and divided and input to the square wave pulse voltage width detecting means 29. The square wave pulse voltage width detecting means 29 checks the count value when the falling edge of the pulse is detected. Since the count value corresponds to the elapsed time from the step switching timing, this count value is stored in the storage means 29A as the square wave pulse voltage width for the excitation pattern # 1 (UV energization).

In step 1, processing such as the square wave pulse voltage width detecting means 29 is executed and the counter is counted up. When the count value reaches the same predetermined value as in step 0, the counter is reset and the process proceeds from step 1 to step 2. In step 2, excitation pattern # 2 is used, and the duty of the pulse width modulation signal is set to 100%. The remaining V phase is opened. In step 3, the duty is set to 0%, and neither phase is energized, and the count value when the edge of the square wave pulse voltage generated in the W phase falls is examined, and the excitation pattern # 2 (UW energization) The square wave pulse voltage width is stored in the storage means 29A.
In step 4, the U phase is released by energizing with excitation pattern # 3. In Step 5, without energizing any phase, the pulse width of the square wave pulse voltage generated in the W phase is examined and stored in the storage means 29A as the square wave pulse voltage width for the excitation pattern # 3 (VW energization).
In Step 6, the W phase is released by energizing with excitation pattern # 4. In step 7, without energizing any phase, the pulse width of the square wave pulse voltage generated in the U phase is checked and stored in the storage means 29A as the square wave pulse voltage width for excitation pattern # 4 (VU energization).
In step 8, energization is performed with excitation pattern # 5 to release the V phase. In step 9, without energizing any phase, the pulse width of the square wave pulse voltage generated in the U phase is checked and stored in the storage means 29A as the square wave pulse voltage width for excitation pattern # 5 (WU energization).
In step 10, the U phase is released by energizing with excitation pattern # 6. In step 11, without energizing any phase, the pulse width of the square wave pulse voltage generated in the V phase is examined and stored in the storage means 29A as the square wave pulse voltage width for the excitation pattern # 6 (WV energization).

Then, at the timing of step 12 following step 11, the rotor position estimation unit 31 has the respective square wave pulse voltages of the excitation patterns # 1 to # 6 stored in the storage unit 29 </ b> A of the square wave pulse voltage width detection unit 29. The excitation pattern having the minimum value is checked from the width, and the rotor position where the inductance is minimized by the excitation pattern is set as the stop position of the rotor 41. In the example of FIG. 6, since the magnetic flux flows most easily in the excitation pattern # 6, the pulse width of the square wave pulse voltage of the excitation pattern # 6 is the smallest. The position of the rotor 41 at this time is the stop position.
The details of the processing of the rotor position estimating means 31 will be specifically described. When it is known in advance that the count value of the square wave pulse voltage width is 1000 or less, the initial value is set to 1000 in the memory storing the minimum value. A larger value is stored and compared with the count value of the square wave pulse voltage width of excitation pattern # 1. When the count value is small, the data stored in the minimum value memory is replaced with the count value of the excitation pattern # 1 from the initial value. The data of the minimum value memory and the count values of all the square wave pulse voltage widths are compared in order, and the smaller count value is stored in the minimum value memory. Finally, the stored count value becomes the minimum value, and the excitation pattern at that time becomes the excitation pattern in which the square wave pulse voltage width is minimized.

  Details of step S104 will be described. The starting excitation means 36 selects an excitation pattern delayed by 120 ° in the rotation direction from the excitation pattern having the smallest square wave pulse voltage width as the excitation pattern at the start. This will be described with reference to a specific example in FIG. In FIG. 8, the horizontal axis is the phase (electrical angle), and the vertical axis is the torque. Line L1 indicates cogging torque, and lines L2 to L4 indicate the relationship between phase and torque in energization patterns # 6, # 1, and # 2, respectively. For example, if the square wave pulse voltage width is the smallest in the excitation pattern # 6 energized from the W phase to the V phase, and the excitation pattern # 6 is the starting excitation pattern, the torque at the electrical angle of 0 ° is zero, so the brushless motor 1A and 1B cannot be rotated. When the electrical angle is 0 °, the positive torque is large in the excitation pattern # 1 (60 ° phase-lag energization) advanced by 1 and the excitation pattern # 2 (120 ° phase-lag energization) advanced by two. However, when starting with the excitation pattern # 1 shown in the line L3, the torque decreases thereafter, so that the force for rotating the rotor 41 is small. On the other hand, when starting with the excitation pattern # 2 shown in the line L4, since the torque increases thereafter, the rotor 41 can be rotated with a large force.

Each process so far will be described in more detail with reference to FIG. FIG. 9 shows the case where the horizontal axis indicates the passage of time, various pieces of information are arranged in the vertical direction, and the plurality of parallel motors 1 are started synchronously. The hall sensor combined signal shown on the uppermost side is a signal assumed as an output of the hall sensor when the hall sensor is attached.
When the start signal is input at time t1, the rotor stop position detection process (step S103) is performed until time t2. The rotation speed during this time is zero.

When the rotor stop position is determined at time t2, as shown in the current waveforms of the shunt resistors 13A and 13B, the starting excitation means 36 continues to supply the starting excitation pattern for the initial energizing time Ts1 (step S104). During this time, the rotational speed of the rotor 41 gradually increases.
Here, the initial energization time Ts1 is such that the rotor 41 can be free-runned at a rotational speed of N1 or more until the edge of the induced voltage is generated a plurality of times, for example, four times or more after the energization is turned off. This is the time during which 41 can be accelerated. From this viewpoint, it is desirable that the initial energization time Ts1 is long. However, if the initial energization time Ts1 is too long and the same excitation pattern is continued beyond the excitation pattern switching position during normal operation, reverse torque is generated and the rotor 41 is decelerated. Therefore, it is preferable that the initial energization time Ts1 is as long as possible within a range where no reverse torque is generated. As an example of a method for determining the initial energization time Ts1, the brushless motors 1A and 1B are started with a hall sensor at the design stage and the manufacturing stage, and the time until the signal of the hall sensor is switched first is measured. For example, the control device 11 may store the time or a shorter time as the initial energization time Ts1.

  When the initial energization time Ts1 has elapsed at time t3, the free-run control means 35 turns off the energization of all phases (corresponding to step S106). The current value measured by the shunt resistors 13A and 13B becomes zero, and the rotor 41 free-runs. Thereafter, the rotational speed gradually decreases with time. At time t3, a pulse appears in each position signal. Therefore, the first signal SL1 is generated as the excitation switching timing signal corresponding to the rising edge of the three-phase composite signal. At this time, the pulse signal is generated due to the fact that square wave pulse voltages are generated in the motor terminal voltages of all three phases when the energy accumulated in the stator coil is released as a flywheel pulse. In the case of normal driving, these square wave pulse voltages can be ignored by the separating means 21, but since the logic turns off all phases at time t3, the square wave pulse voltage can be ignored because it becomes an exceptional state that cannot exist during normal driving. Without false detection. For this reason, the first signal SL1 after starting is not used for detecting the rotor position.

  Furthermore, the two rotors 41 are free-running synchronously, so that a signal in which the induced voltage is combined is generated at a predetermined phase motor terminal of the plurality of parallel motors 1 according to the rotational position of the rotor 41. In this case, rising edges or falling edges occur in the order of the W-phase position signal, the U-phase position signal, and the V-phase position signal. As a result, the excitation switching timing signal includes the second signal SL2 caused by the W-phase edge, the third signal SL3 caused by the U-phase edge, and the fourth signal SL4 caused by the V-phase edge. Will occur. By turning off all phases, the intersection of the induced voltage and the equivalent neutral point potential can be measured in the absence of unnecessary signal components such as pulse width modulation signals input from the inverter 13 to the brushless motors 1A and 1B. As a result, the rotor position can be accurately detected.

  During this time, the excitation switching timing calculation means 22 measures the time interval between the second signal SL2 and the third signal SL3 to calculate an electrical angle of 60 °. Furthermore, an electrical angle of 60 ° is calculated by measuring the time interval between the third signal SL3 and the fourth signal SL4. Based on these time intervals, the excitation switching timing is calculated by, for example, advancing the electrical angle by 30 ° from the fourth signal SL4. Thereafter, two brushless motors are determined by determining the excitation switching timing based on the three-phase composite signal generated from the comparison result of the motor terminal voltage and the equivalent neutral point potential, and performing switching control of the energization pattern. Synchronous operation of 1A and 1B is performed. Driving with a performance equivalent to that of a rectangular wave driving with an electrical angle of 120 ° in the case of having a Hall sensor is possible, and the rotation speed is controlled.

Note that in a brushless motor with a large inertia, the fifth and subsequent signals may be acquired, and the excitation energization timing may be similarly calculated from the time interval. Stability and accuracy at start-up can be further improved.
In a brushless motor having a large inertia, the time interval between the second and third signals SL2 and SL3 is substantially equal to the time interval between the third and fourth signals SL3 and SL4. For this reason, you may transfer to sensorless drive only in the time interval of the 2nd to 3rd signals SL2 and SL3. In this way, steady operation can be started in a shorter time. Alternatively, only the time interval between the first signal SL1 and the second signal SL2 may be acquired to shift to sensorless driving. Effective for brushless motors with low inertia. In this case, the initial energization time SL1 uses a preset value, and when the SL2 timing is detected, the time interval between SL1 and SL2 can be calculated and used as the rotor position signal. It becomes possible to shift to sensorless driving up to the second signal SL2.
Further, in a brushless motor with small inertia, the deceleration is increased and the time interval between the third and fourth signals SL3 and SL4 is larger than the time interval between the second and third signals SL2 and SL3. In this case, the excitation energization timing may be calculated by calculating the acceleration from the change in the time interval and estimating the next time interval using this acceleration.

  Further, in this starting method, a method of starting while suppressing the current at the time of starting the motor (hereinafter referred to as soft start) is implemented. For example, as shown in FIG. 10, at the time of start-up, the duty of the pulse width modulation signal (PWM) is set to 50%, the current is suppressed, and then the rotation speed is increased. After the initial energization time Ts1 has elapsed, the duty is once set. Set to 0% and free run. When the free run is completed, the duty is again set to 50%, and then the duty is gradually increased so that the rotational speed reaches the target value (for example, the maximum rotational speed) when the duty finally reaches 100%. . As a result, it is possible to prevent an overcurrent from flowing at the start, and to improve the stability of the entire system in which the brushless motors 1A and 1B are mounted.

Details of the sensorless drive (steady drive mode) by the induced voltage in step S109 will be described.
In the steady drive mode, the rotor position is detected by detecting the induced voltage of the motor terminal (that is, a signal obtained by synthesizing the induced voltages of the brushless motors 1A and 1B). The induced voltage waveform includes a square-wave switching pulse (square shape). Such a noise needs to be removed. In this embodiment, when an edge corresponding to the rotor position signal of each phase is detected, the level of the other phase is detected to distinguish the rotor position signal from the square wave pulse voltage. The forward rotation dedicated logic used at this time includes an induced voltage signal detection logic shown in Table 1 and a square wave pulse voltage end edge determination logic shown in Table 2. Note that the forward rotation dedicated logic is separated by the command of the rotation direction detection logic selection unit 24 when the rotation direction determination unit 23 shown in FIG. 1 determines that the brushless motors 1A and 1B are rotating in synchronization with each other. 21 refers to.

  FIG. 11 shows signal waveforms when energization control is performed in the steady drive mode. In FIG. 11, the horizontal axis represents the electrical angle, and the vertical axis represents the energization state from the upper side to each phase U, V, W and the actual induced voltage waveforms Uv, Vv, Wv (analogue) of each phase U, V, W. Signal) and induced voltage signals Ud, Vd, Wd (digital signals) for phases U, V, W are shown. The energization state of the uppermost phases U, V, W is such that the phases U, V, W added with “+” in the upper stage are on the high potential side, and the phases U, “-” added in the lower stage, V and W are on the low potential side. That is, “W +” and “V−” between 0 ° and 60 ° in electrical angle indicate that the W phase is energized from the W phase (equivalent to the energization pattern # 6 in FIG. 6). Further, for example, in the induced voltage waveform Uv, a pulse that rises at an electrical angle of 0 ° and a pulse that falls at an electrical angle of 180 ° are square wave pulse voltages Ps, and these square wave pulse voltages Ps are to be removed in this embodiment. Is a signal.

FIG. 12 is a diagram schematically showing a mask signal generation process and a position detection signal generation process. In FIG. 12, the horizontal axis represents the electrical angle, and the vertical axis represents the induced voltage signals Ud, Vd, Wd (the same signals as in FIG. 11) of the phases U, V, W from the upper side, and the induced voltage signal Ud, Vd, Wd mask signal for separating the rectangular-wave pulse voltage P s superimposed on each Um, Vm, Wm and, Ud by said mask signal, Vd, a square wave pulse voltage signal Ups separated from Wd , Vps, Wps, position detection signals Us, Vs, Ws of each phase U, V, W, and position detection signals Uss, Vss, Wss after phase shift of 30 electrical degrees are illustrated in order.

  The induced voltage waveforms Uv, Vv, and Wv of the phases U, V, and W shown in FIG. 11 are input to the induced voltage I / F circuit 12 (see FIG. 1), and are compared by the voltage dividing circuits of the low-pass filter circuits 15A to 15C. The voltages are divided into voltages Uv2, Vv2, and Wv2 that can be input to 17A to 17C. Thereafter, the induced voltage signals Uv3, Vv3, and Wv3 after the PWM noise is removed by the low-pass filter circuits 18A to 18C are generated, and an equivalent neutral point voltage is obtained from these voltage values. When this equivalent neutral point voltage and the induced voltage waveform Uv3 are input to the comparator, an induced voltage signal Ud is obtained. Similarly, the induced voltage signals Vd and Wd of the digital signal are obtained from the induced voltage waveforms Vv3 and Wv3 of the analog signal. These induced voltage signals Ud, Vd, Wd are input to the separating means 21 of the control device 11, and the energization switching timing is generated by the following processing.

Separating means 21, the induced the induced voltage signals Ud, Vd, from the pulse signal Wd, separating the edge of the induced voltage generated by rotation of the edge and the rotor 41 of the square-wave pulse voltage Ps, caused by rotation of the B over data 41 Position detection signals Us, Vs, and Ws composed of voltage information are created and transferred to the excitation switching timing calculation means 22. The excitation switching timing calculation means 22 counts the intervals Te between the edges (induced voltage edges) of the position detection signals Us, Vs, Ws shown in FIG. Specifically, measurement by the counter is started using all edges of the position detection signals Us, Vs, and Ws as triggers, and the count value is cleared when any edge of the position detection signals Us, Vs, and Ws is detected next. At the same time, the next count is started. Here, when the brushless motors 1A and 1B are rotating synchronously, the interval Te of the induced voltage edge is generated every 60 ° of electrical angle, and therefore the rotation of the rotor 41 is determined from the count value indicating the generation interval of the induced voltage. The speed and acceleration are calculated, the timing for switching the energization next is corrected accordingly, and the phase of the position detection signals Us, Vs, Ws is shifted by that amount to generate the phase detection signals Uss, Vss, Wss. Then, the excitation voltage output means 27 controls the inverter 13 in accordance with the phase detection signals Uss, Vss, Wss, and switches the energization to the stator windings U, V, W, and the respective rotors of the brushless motors 1A, 1B. 41 is rotated.

Here, the excitation voltage output means 27 is provided with a mask signal generation means 27A. The mask signal generation means 27A outputs a mask signal to the separation means 21 immediately before the excitation voltage output means 27 outputs an energization pattern to the inverter. To do.
For example, in the example of FIG. 12, the W-phase mask signal Wm is set to the H (High) level immediately before the occurrence timing of the edge of the U-phase position detection signal Uss. Similarly, the U-phase mask signal Um is set to the H (High) level immediately before the edge generation timing of the V-phase position detection signal Vss. Immediately before the occurrence timing of the edge of the W-phase position detection signal Wss, the V-phase mask signal Vm is set to the H (High) level. The signal levels of these mask signals Um, Vm, Wm are changed to L (Low) level after being maintained for a predetermined electrical angle.

  Note that the electrical angle that determines the pulse width of the mask signals Um, Vm, and Wm is always calculated in advance from the measured value of Te. Specifically, the intersection of the induced voltage waveforms Uv, Vv, Wv and the equivalent neutral point voltage is masked by the pulse of the mask signal, which is larger than the pulse width of the square wave pulse voltage Ps when rotated by a normal load. A value such that 0 ° <θ <30 ° is used.

  Thereafter, with respect to the induced voltage signals Ud, Vd, Wd input from the induced voltage I / F circuit 12, the pulses of the square wave pulse voltage Ps are removed by the mask signals Um, Vm, Wm, and the position detection signals Us, Vs and Ws are created, and energization control of the plural parallel motors 1 is performed.

  Here, the pulse width of the square wave pulse voltage Ps varies depending on the size of the load and the rotation speed. On the other hand, since the mask signals Um, Vm, and Wm have a constant pulse width, there are cases where the mask signal Um, Vm, and Wm can completely mask the pulse of the square wave pulse voltage Ps and cases where the mask signal cannot be completely masked. Arise.

  First, when the pulse width of the square wave pulse voltage Ps is equal to or smaller than the mask width, both the start edge and the end edge of the square wave pulse voltage Ps can be masked as shown in FIG. In this case, the separating unit 21 creates the position detection signals Us, Vs, Ws from the induced voltage signals Ud, Vd, Wd according to the induced voltage signal detection logic as shown in Table 1.

  In FIG. 13, the rising edge and falling edge of the square wave pulse voltage Ps starting from the electrical angle θ1 are ignored because the mask signal Um is at the H level. Since the rising edge at the electrical angle θ2 satisfies the condition for the induced voltage signal Ud of the rising edge in Table 1, it is regarded as the rising edge of the U-phase induced voltage. Similarly, the falling edge and rising edge of the square wave pulse voltage Ps starting from the electrical angle θ3 are ignored because the mask signal Um is at the H level. Since the falling edge of the induced voltage signal Ud at the electrical angle θ4 satisfies the conditions for the induced voltage signal Ud of the falling edge in Table 1, it is regarded as the falling edge of the induced voltage of the stator winding U. Similarly, with respect to the other induced voltage signals Vd and Wd, the rising edge and the falling edge of the induced voltage are determined according to the induced voltage signal detection logic shown in Table 1, and the position detection signals Us, Vs, and Ws are created.

  On the other hand, as shown in FIG. 14, when the pulse width of the square wave pulse voltage Ps exceeds the mask width, the start edge of the square wave pulse voltage Ps can be masked, but the end edge of the square wave pulse voltage Ps. Can not be masked. In such a case, the separation means 21 refers to the square wave pulse voltage end edge determination logic as shown in Table 2 in addition to the induced voltage signal detection logic as shown in Table 1 and determines the induced voltage edge. The position detection signals Us, Vs, and Ws are created.

  In FIG. 14, the rising edge of the square wave pulse voltage Ps starting from the electrical angle θ1 is masked, but the falling edge of the same square wave pulse voltage Ps cannot be masked. Therefore, the falling edges shown in Tables 1 and 2 are used. It is checked whether or not the condition of the above is satisfied. In this case, since the condition for the induced voltage signal Ud of the falling edge in Table 2 is satisfied, it is regarded as the edge of the square wave pulse voltage Ps, and the position detection signal Us is created after removing this signal. The edge of the electrical angle θ2 satisfies the conditions in Table 1 as described above, and is therefore an induced voltage edge. Similarly, the falling edge of the square wave pulse voltage Ps starting from the electrical angle θ3 is removed by the mask signal Um, and the rising edge of the same square wave pulse voltage Ps is the condition for the induced voltage signal Ud of the rising edge in Table 2. Since it satisfies, it is removed. In this way, when there is a pulse of the square wave pulse voltage Ps that cannot be removed by the mask signal Um, the level of the voltage levels of the other induced voltage signals Vd and Wd is examined and the conditions shown in Tables 1 and 2 are obtained. To determine whether or not it is necessary to remove the signal, and a signal based on the square wave pulse voltage Ps is removed to generate the position detection signal Us. Further, similarly, the position detection signals Vs and Ws are created.

  Here, a process for correcting the timing of switching energization when generating the phase detection signals Uss, Vss, Wss will be described. The correction is performed by a delay phase correction unit 22A provided in the excitation switching timing calculation unit 22. FIG. 15 shows the delay phase to be corrected. FIG. 15 schematically shows the excitation timing and delay phases θ1 and θ2 in the U phase. The delay phase θ1 is caused by the low-pass filter circuits 15A to 15C of the induced voltage I / F circuit 12, and changes depending on the rotation speed. The delay phase θ2 is the sum of the delayed component θ2a of the induced voltage I / F circuit 12 from the comparators 17A to 17C, that is, the comparators 17A to 17C and the low-pass filters 18A to 18C, and the processing delay time θ2b of the microcomputer of the control device 11 ( θ2 = θ2a + θ2b), which is a value unique to the driving device 2. Therefore, the delay phase correction unit 22A functions as a filter delay phase correction unit that corrects the delay phase θ1 and a circuit delay phase correction unit that corrects the delay phase θ2.

First, the processing of the delay phase correction unit 22A as the filter delay phase correction means will be described.
When the range R5 shown in FIG. 16 is the control range of the rotational speeds of the brushless motors 1A and 1B, the low-pass filter circuits 15A to 15C have the cutoff frequency fc set in a frequency region higher than the range R5. FIG. 16 is a Bode diagram in which the horizontal axis represents logarithm of frequency and the vertical axis represents phase. A delayed phase θ1 is generated in the induced voltage signal that has passed through the low-pass filter circuits 15A to 15C having the cutoff frequency fc. The delay phase θ1 increases as the frequency increases.

The transfer function G (s) of the low-pass filter circuits 15A to 15C can be expressed by the following equation using τ (= C × R).
G (s) = 1 / (τs + 1) (1)
From equation (1), the delay phase θ1 [rad] is
θ1 = −arctan (ωτ) (2)

Here, the angular acceleration ω can be expressed as a function of the fundamental frequency f of the motor terminal voltage corresponding to the rotational speed.
θ1 = −arctan (2πτ × f) (3)
It becomes. If you change the unit to [°] and take the delay,
θ1 = arctan (2πτ × f) × 360 / 2π (4)
It becomes. If the time required to rotate the electrical angle of 60 ° is Ta, 1 / f = 6Ta,
θ1 = arctan (2πτ / 6Ta) × 360 / 2π (5)
The delay phase θ1 by the filters 15A to 15C can be calculated from Expression (5). The delay phase θ1 may be calculated each time from the equation (5), but in this embodiment, the map is registered in the delay phase correction unit 22A, and the delay phase θ1 is obtained by searching at the time Ta.

Next, processing of the delay phase correction unit 22A as circuit delay phase correction means will be described.
Delay phase θ2 is generated by other circuitry and software processing other than filter 15A to 15C. This delay phase θ2 is generated due to comparators 17A to 17C, low-pass filter circuits 18A to 18C, a microcomputer, and the like. The delay time T2 at this time is a constant value regardless of the rotation speed. Therefore, the delay phase θ2 can be calculated from the ratio of the delay time T2 to the time Ta required to rotate the electrical angle of 60 °.
θ2 = (T2 / Ta) × 60 [°] (6)

  From equation (6), it can be seen that since the delay time T2 is constant, the value of T2 / Ta increases and the delay phase θ2 increases as the rotational speed increases and the time Ta decreases. If equation (6) is also mapped, the calculation can be performed smoothly.

From the above, the timing Ew for switching excitation is
Ew = 30− (θ1 + θ2) (7)
become. By correcting the timing Ew using the map, the timing Ew can be quickly calculated. Further, by using the corrected timing Ew, the excitation can be switched with high accuracy regardless of the rotation speed.

Next, the case where the rotational speed is already in the region R2 at the start will be described.
As shown in FIG. 17, the state before starting becomes the same as the above-described free-run state. Even if the processing from step S103 to step S106 is performed according to the flowchart of FIG. 5, the free running state is hardly affected and the free running state can be maintained. Therefore, the process proceeds from step S108 to step S109 to shift to the steady drive mode.

The case where the rotational speed is in the region R3 or region R4 shown in FIG. 4 at the start will be described.
Even if step S101 to step S107 in FIG. 5 are performed, the signal waveform obtained by synthesizing the induced voltages of the two rotors 41 rotating in the reverse direction or the induction of the two rotors 41 rotating asynchronously. The rotor position signal cannot be extracted by the forward rotation dedicated logic in the signal waveform obtained by synthesizing the voltages. Therefore, when the rotor position signal cannot be detected for a predetermined time of, for example, about 1 to 9 seconds (equivalent to step S110), it is determined that the rotation direction determination means 23 is in the reverse rotation state or the asynchronous state.
In this case, the control device 11 shown in FIG. 1, a brake stop means time 25 is constant two-phase lock energization is applied at a low degree of duty not become over-current brushless motor 1A, the 1B. The radiator fan acts as a brake, and the rotation speed of the radiator fan is reduced to approach the stop state. When the two brushless motors 1 </ b> A and 1 </ b> B are rotating asynchronously, the rotors 41 can be brought into a stopped state and consequently synchronized.

FIG. 18 shows a change in the rotational speed when reversely rotating in synchronization. The time for which the two-phase lock energization is continued is a preset brake energization time, for example, about 1 to 9 seconds. As a result, the rotational speeds of the brushless motors 1A and 1B approach from -N1 to zero. This is because, as described above, the radiator fan has a small number of rotations and torque when it is rotating in the reverse direction.
FIG. 19 shows a change in rotational speed in the case of asynchronous. Until the rotor state is detected before starting (step S110 in FIG. 5), the rotations of the brushless motors 1A and 1B are indefinite. When the synchronization process by applying the brake is performed, the rotational speed gradually approaches zero. As a result, the brushless motors 1A and 1B are synchronized, so that the brushless motors 1A and 1B are driven to the rated rotational speed in a synchronized state by performing the processing after step S103 in FIG.

  When the brake energization time has elapsed, start processing using inductance detection is performed. Since the radiator fan is a system with high friction, the mechanical time constant is large, and if it is forcibly stopped during reverse rotation, it takes time to start rotating in the reverse direction again due to the wind force. This is because it stays at R1. Thereafter, the above-described steps S103 to S108 are performed, and the routine shifts to the steady drive mode.

According to this embodiment, it is possible to examine the magnitude of the inductance from the square wave pulse voltage width by performing two-phase energization. The pulse width is easier to measure than in the case of measuring the voltage rise time as in the prior art, and it is not necessary to add a special circuit. The apparatus configuration can be simplified and the manufacturing cost can be reduced.
When the magnetic flux generated by the coil and the magnetic flux generated by the magnet are in the same direction, that is, the rotor position where the magnetic flux easily flows between the coil and the magnet, the inductance is reduced. In addition, the rotor stop position can be detected stably.
When changing from N-pole magnetization to S-pole magnetization in the order of excitation patterns for generating square-wave pulse voltage, that is, the search order of the rotor stop position, an excitation pattern that is not energized during that time is executed. Since the switching order is adopted, it is difficult to be affected by the residual magnetization of the iron core around which the coil is wound, and the inductance detection accuracy can be improved.

  The rotor position estimating means 31 may check the maximum value instead of checking the minimum value of the square wave pulse voltage width. In this case, the square-wave pulse voltage width detection unit 29 stores the largest pulse width in the storage unit 29A in association with the excitation pattern at that time. The starting excitation unit 36 starts the brushless motors 1A and 1B by selecting the energizing pattern delayed by 60 ° in the rotation direction from the excitation pattern giving the maximum value of the pulse width by the starting excitation unit 36. For example, in the example shown in FIG. 6, the excitation pattern # 3 hardly flows the magnetic flux and the square wave pulse voltage width becomes large. Therefore, the previous excitation pattern # 2 is determined as the starting excitation pattern.

  Further, the square wave pulse voltage width may be measured a plurality of times. For example, a process when measuring twice is described with reference to FIG. In the stop position inspection in this case, the energization control is performed with 24 steps 0 to 23 as one set, and the stop position is estimated in the 25th step 24. In Step 0 and Step 1, the excitation pattern # 1 is energized and then released, and the pulse width of the square wave pulse voltage generated in the W phase is counted. In step 2 and step 3, the same processing as in step 0 and step 1 is repeated. Steps 4 and 5 and steps 6 and 7 perform the same processing for the excitation pattern # 2. Thereafter, until the step 23, the same square wave pulse voltage width is counted twice in order for each of the excitation patterns # 3 to # 6.

At this time, the square wave pulse voltage width detection means 29 has the entire square wave pulse voltage width (count value) measured twice in the storage means 29A or only the square wave pulse voltage width (count value) measured second time. Are stored in association with the excitation pattern. In the stop position estimation process of step 24, the square wave pulse voltage width measured for the second time is compared in the same manner as described above. The excitation pattern having the smallest square wave pulse voltage width is determined as the starting excitation pattern.
In this way, when the brushless motors 1A and 1B are configured to be easily affected by the residual magnetization of the coil core, the influence of the residual magnetization can be further reduced and the inductance detection accuracy can be improved.

  Here, the stop position estimation process may calculate an average value of square wave pulse voltage widths (count values) measured a plurality of times for the same excitation pattern, and compare the magnitudes of the average values in the same manner as described above. . By performing the averaging process, the inductance detection accuracy can be further improved. Even when the square wave pulse voltage width is acquired a plurality of times, the rotor stop position and the start excitation pattern may be determined by examining the maximum value instead of the minimum value.

In this embodiment, since the free-run state is created when the brushless motors 1A and 1B are started, the position of the rotor 41, which has started rotating with all phases opened, is detected without noise. It becomes possible. For this reason, the rotor position can be detected promptly and accurately.
Since the energization time (Ts1) until free running is within a range where no reverse torque is generated, the rotor 41 is not greatly decelerated during free running, and the rotor position can be detected correctly.
If the second and subsequent signals SL2 to SL4 are used without using the first signal SL1 generated at the time of free-running, correct detection is possible even when a signal due to the square wave pulse voltage is generated the first time. .

  Here, such brushless motors 1A and 1B are, for example, fan motors, motors of fuel pumps, motors with large inertia, slotless motors without cogging torque, low loss motors with low loss due to friction, cogging torque, etc. Can be given. In a slotless motor, the rotor stop position cannot be detected by inductance detection because there is no slot core. However, since the inertia is extremely small, it can be easily sucked to the predetermined rotation position by energization when detecting the stop position of the rotor. Therefore, the stop position is determined by such a method, and the electric angle 120 is determined therefrom. ° Energization pattern with delayed phase may be selected as starting excitation pattern. As described above, the method for detecting the rotor stop position and the method for determining the starting excitation pattern are not limited to the method based on the inductance, and various methods can be used.

  Further, according to this embodiment, when starting the brushless motors 1A and 1B, even when the rotor 41 is rotating in reverse or asynchronously, the coil inductance is reduced by performing the braking process. The used rotor position can be detected. From this point, the brushless motors 1A and 1B can be started to promptly shift to steady operation by 120 ° energization. Rotation at start-up, such as when the rotor 41 is synchronously rotating forward / reversely due to the influence of wind or the like when the brushless motors 1A, 1B are not energized, stopped, or rotated asynchronously It becomes possible to start reliably regardless of the state, and the brushless motors 1A and 1B can be reliably started. For example, when the brushless motors 1A and 1B are used for driving a radiator fan of an engine cooling system such as an automobile, the reliability of the system can be improved.

(Second Embodiment)
This embodiment is characterized in that reverse rotation dedicated logic is used in addition to forward rotation dedicated logic. The apparatus configuration is the same as that of the first embodiment.
FIG. 21 shows a flowchart of the operation at the start. Processing from step S101 to step S108, that is, when the rotation speed of the brushless motors 1A and 1B at the start of the start is in the region R1 or region R2 in FIG. 4 is the same as that in the first embodiment. When the rotation speed at the start is the region R3 or the region R4, the process proceeds from step S108 to step S110A.

  In step S110A, the induced voltage is detected and the rotor position is detected using the reverse rotation dedicated logic. The reverse rotation dedicated logic is selected by the rotation direction detection logic selection unit 24 when the rotation direction determination unit 23 determines that the rotation is reverse. The induced voltage signal detection logic shown in Table 2 and the square wave pulse voltage shown in Table 1 are selected. It consists of end edge determination logic and is registered in the separation means 21. Using such reverse rotation dedicated logic, when an edge corresponding to the rotor position signal of each phase is detected, the level of the other phase is detected to distinguish the rotor position signal from the switching pulse and detect the rotor position. . The processing here is the same as in the steady drive mode in the first embodiment, except that the logic used is different.

When the rotor position detection process is performed and a rotor position detection signal is actually obtained (Yes in step S110B), steps S111A and S112A are performed. The rotor position detection signal only needs to be generated once or more as long as it can be confirmed that the rotation is reverse. The processing of steps S111A and S112A is the same as steps S111 and S112 of the first embodiment.
On the other hand, if the rotor position detection signal is not obtained (No in step S110B), after waiting for a predetermined number of overflows of the counter that measures the interval between the induced voltage edges (Yes in step S110C), It progresses to step S111B and step S112B. The processing of steps S111B and S112B is the same as steps S111 and S112 of the first embodiment.

  In this embodiment, the reverse rotation state can be reliably detected by using the reverse rotation dedicated logic. Other effects are the same as those of the first embodiment.

(Third embodiment)
This embodiment is characterized in that the brake processing is first performed.
As shown in FIG. 22, after performing an overcurrent detection process (step S101), a two-phase energization lock process with a low duty is performed (step S102A). The brake time is a fixed time (step S102B). These processes are processes corresponding to steps S111 and S112 in the first embodiment. Even when the rotational speeds of the brushless motors 1A and 1B are in any of the regions R1 to R4 at the time of starting, the control is forcibly controlled to the region R1 by the brake process. Subsequent processing is the same as in the first embodiment.

  Also, as shown in FIG. 23, when the reverse rotation dedicated logic is used (corresponding to step S110A), by first performing the brake process in steps S102A and S102B, the rotational speed of the brushless motors 1A and 1B can be set to any value. Even in the regions R1 to R4, the region is forcedly controlled to the region R1 by the brake process. After using the reverse rotation dedicated logic, the system waits until the number of times of measuring the interval between the induced voltage edges elapses (Yes in Step S110B), and when the rotor position can be detected a predetermined number of times (Step S110B). Yes in S121), the process returns to step S101. An example of such a case is when it is in the region R3. If the rotor position cannot be detected a predetermined number of times (No in step S121), the process waits until the number of times of measuring the interval between the induced voltage edges elapses (Yes in step S122), and then returns to step S101. An example of such a case is when it is in the region R4.

Note that the present invention can be widely applied without being limited to the above-described embodiment.
For example, when the voltage at the motor terminal varies, such as when the power supply voltage varies, it is desirable to use a level conversion circuit instead of the voltage dividing circuit 14. The level conversion circuit uses transistors, FETs, comparators, and the like, and is configured so that the terminal voltage can be lowered according to the power supply voltage.
The energization control at the start is not limited to 50% duty as long as the current value is monitored from the shunt resistors 13A and 13B and controlled so as not to exceed a predetermined value.
The initial energization time Ts1 may be obtained by substituting predetermined physical constants into the voltage / current equation and the position / torque equation, or may be determined by simulation.

If the initial energization time Ts1 alone cannot be used to accelerate to a rotational speed sufficient for rotor position detection, forced energization by several open loops may be performed to sufficiently accelerate and then shift to a free-run state. For example, as shown in FIG. 24, the first energization switching timing (initial energization time Ts1) is determined using the Hall sensor, and the second energization switching timing (energization time Ts2) and the third energization are performed. The switching timing (energizing time Ts3) is also measured, and these energizing times Ts1 to Ts3 are stored in the control device 11 as programs. At the start, the start excitation pattern is continued for the initial energization time Ts1, the next excitation pattern for the start excitation pattern is continued for the time Ts2, and the next excitation pattern is continued for the time Ts3. Free run.
In FIG. 8, when the brushless motors 1 </ b> A and 1 </ b> B are reversely rotated at the start, an excitation pattern advanced by 120 ° is selected as an excitation pattern at the start.
The multiple parallel motor 1 may have a configuration in which three or more brushless motors are connected in parallel. In this case, the number of FETs connected in parallel in the inverter circuit 13 may be increased according to the number of brushless motors.

It is a block diagram which shows schematic structure of the drive device of the brushless motor which concerns on embodiment of this invention. It is a figure which illustrates the specific circuit structure of an induced electric power I / F circuit. It is a figure which shows the structure of an inverter circuit and an overcurrent detection circuit in detail. It is a figure which illustrates typically that a process changes with the rotational speed at the time of a start. It is a flowchart explaining the outline | summary of the process at the time of starting. It is a figure which illustrates typically the flow of the magnetic flux when it supplies with the excitation pattern at the time of a start, and the excitation pattern. It is a graph explaining the procedure and timing which measure the square wave pulse voltage width with respect to each excitation pattern. It is a graph for demonstrating the relationship between a rotor position and a starting excitation pattern. It is a timing chart for explaining processing at the time of starting concretely. It is a figure which shows the duty control in the case of carrying out a soft start, and a rotational speed. It is a figure explaining the signal processing of the induced voltage waveform of a stator winding, Comprising: It is a timing chart which shows the procedure which produces a digital signal from an analog signal. It is a figure explaining the signal processing of the induced voltage waveform of a stator winding, Comprising: It is a timing chart which shows the preparation procedure of a mask signal, and the preparation procedure of the position detection signal after a mask process. It is a timing chart explaining the determination process of an induced voltage edge, Comprising: It is a figure which shows the case where the pulse width of a square wave pulse voltage is below the pulse width of a mask signal. It is a timing chart explaining the determination process of an induced voltage edge, Comprising: It is a figure which shows the case where the pulse width of a square wave pulse voltage exceeds the pulse width of a mask signal. It is a figure which shows the excitation timing of a U phase. It is a figure which shows the delay phase of the motor terminal voltage waveform with respect to a frequency. 5 is a timing chart when starting from a region R2 in FIG. 4. 6 is a timing chart when starting from a region R3 in FIG. 6 is a timing chart when starting from a region R4 in FIG. It is a figure explaining the procedure and timing in the case of measuring a square wave pulse voltage width twice. It is a flowchart explaining the outline | summary of the process at the time of starting. It is a flowchart explaining the outline | summary of the process at the time of starting. It is a flowchart explaining the outline | summary of the process at the time of starting. It is a figure which shows concretely the method of determining the energization time in the case of performing the open loop control to the method of determining initial energization time, and three energization switching.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Plural parallel motor 1A, 1B Brushless motor 2 Drive apparatus 11 Control apparatus 14 Voltage dividing circuit 15A, 15B, 15C Filter 22 Excitation switching timing calculation means 22A Delay phase correction part (Filter delay phase correction means, Circuit delay phase correction means)
26 energization pattern determination means 27 excitation voltage output means 29 square wave pulse voltage width detection means 31 rotor position estimation means 41 rotor SL2, SL3, SL4 signal Ts1 initial energization time

Claims (17)

A driving device that drives a plurality of brushless motors connected in parallel synchronously,
When the rotational speed of said plurality of brushless motors is in the region forward and reverse rotational speed is smaller contains a zero, by energizing the respective only of said plurality of brushless motors initial energization time the excitation pattern that matches the rotor stop position at start Energization pattern determination means for stopping energization and free-running each rotor of the plurality of brushless motors after the rotational speed of the rotor gradually increases ;
Excitation switching timing calculation means for detecting a rotor position from a signal obtained by synthesizing induced voltages generated in each of the brushless motors during free run of the plurality of brushless motors connected in parallel, and determining an excitation timing;
A drive device for a plurality of brushless motors connected in parallel.   2. The plurality of brushless motors connected in parallel according to claim 1, wherein the initial energization time is equal to or shorter than a time from the start of rotation of the rotor to a first energization switching timing. Drive device.   3. The parallel according to claim 1, wherein the excitation switching timing calculation unit calculates an excitation timing from a time interval of a signal obtained by synthesizing the induced voltage generated after the second time during free run. Drive device for a plurality of brushless motors connected to Excitation voltage output means for selecting a plurality of excitation patterns that can be driven in synchronization with the plurality of brushless motors, and energizing each excitation pattern sequentially in a time range in which the rotor does not rotate,
A square wave pulse voltage width detecting means for detecting a pulse width of a signal obtained by synthesizing a square wave pulse voltage generated in each coil of the plurality of brushless motors when the excitation pattern is switched;
A rotor position estimating means for obtaining a minimum value or a maximum value from a pulse width of a signal obtained by synthesizing the square wave pulse voltage in a plurality of excitation patterns, and determining a stop position of the rotor from an excitation pattern that becomes the minimum value or the maximum value;
An energization pattern that is retarded or advanced by a predetermined electrical angle from the rotor stop position determined by the rotor position estimation means is output as a start excitation pattern. The drive apparatus of the several brushless motor connected in parallel as described in any one of Claims 1-3.   5. The excitation voltage output means implements an excitation pattern in which the coil is not energized between an excitation pattern in which the coil is N-pole magnetized and an excitation pattern in which the same coil is S-pole magnetized. The drive apparatus of the several brushless motor connected in parallel as described in any one of.   When the rotor position estimation means determines the stop position of the rotor from the minimum value of the pulse width of the signal obtained by synthesizing the square wave pulse voltage, it outputs an excitation pattern with a 120 ° phase delay during forward rotation and 120 ° during reverse rotation. 6. The drive device for a plurality of brushless motors connected in parallel according to claim 4, wherein an excitation pattern having a phase advanced is output. Claim claim 4, characterized in that it comprises a voltage divider circuit is input to each of the square-wave pulse voltage width detecting means a square wave pulse voltage generated in the coil combined signal by dividing by said plurality of brushless motors The drive apparatus of the some brushless motor connected in parallel as described in any one of Claims 6-6. When the rotation of the rotor of each of the plurality of brushless motors is reversely rotated in synchronization, a low duty voltage is applied and the excitation voltage output means is operated after braking the rotor. The drive apparatus of the several brushless motor connected in parallel as described in any one of Claims 4-7 characterized by the above-mentioned.   The excitation voltage output means is operated after applying a low-duty voltage and applying a brake to the rotor when rotations of the rotors of the plurality of brushless motors are not synchronized. The drive device of the several brushless motor connected in parallel as described in any one of Claims 4-8.   A filter that removes noise included in a motor voltage detection signal is provided in the means for detecting the voltage at the motor terminal of each phase of the plurality of brushless motors, and the excitation switching timing calculation means varies depending on the rotation speed of the brushless motor. 10. The driving device for a plurality of brushless motors connected in parallel according to claim 9, further comprising a filter delay phase correcting means for correcting a delay phase of the filter.   The driving device for a plurality of brushless motors connected in parallel according to claim 10, wherein the filter is a primary CR filter that removes noise generated when the brushless motor is subjected to pulse width modulation control. .   12. The driving apparatus for a plurality of brushless motors connected in parallel according to claim 11, wherein the excitation switching timing calculation means further includes a circuit delay phase correction means for correcting a delay phase caused by a circuit other than the filter. . A starting method for synchronously starting a plurality of brushless motors connected in parallel,
When the rotational speed of the rotor is in a region including zero and the forward / reverse rotational speed is low , the rotational speed of the rotor is gradually increased by energizing the plurality of brushless motors with an excitation pattern that matches the stop position for the initial energization time. And after that, stopping the energization and free-running each of the rotors of the plurality of brushless motors;
Detecting a rotor position from a signal obtained by combining induced voltages generated in each of the brushless motors during free run of the plurality of brushless motors connected in parallel;
Switching excitation patterns based on the detected rotor position;
A starting method for a plurality of brushless motors connected in parallel.   The initial energization time is equal to or shorter than the time from the start of rotation of the rotor to the first energization switching timing, and the step of detecting the rotor position includes the plurality of brushless motors when the rotor is rotated. 14. The method for starting a plurality of brushless motors connected in parallel according to claim 13, wherein the method is performed until a signal obtained by synthesizing the induced voltages generated in each of the two is generated at least a third time. A rotor with a permanent magnet connected in parallel and a stator, and a plurality of excitation patterns that can be driven synchronously with a plurality of brushless motors in which three-phase coils are wound in order in the circumferential direction are selected on the stator In addition, between the excitation pattern for N-pole magnetization of a phase coil of the plurality of brushless motors and the excitation pattern for S-pole magnetization of the same coil, the coil is not energized so that the residual magnetization of the coil is eliminated. A square that is generated in each of the plurality of brushless motors when the energization order is selected so that the excitation patterns to be energized, the respective excitation patterns are energized sequentially in a time range in which the rotor does not rotate, and the excitation patterns are switched. A plurality of brushes connected in parallel, wherein a stop position of the rotor is determined from a minimum value of a pulse width of a signal obtained by synthesizing a wave pulse voltage Rotor stop position detection method Sumota. In synchronously starting a plurality of brushless motors having a rotor having a permanent magnet connected in parallel and a stator, and three-phase coils wound around the stator in order in the circumferential direction, the plurality of brushless Select a plurality of excitation patterns that can drive the motor, energize each excitation pattern sequentially in the time range in which the rotor does not rotate, and square wave pulse voltage generated in each of the plurality of brushless motors when the excitation pattern is switched Check the pulse width of the combined signal, determine the rotor stop position from its minimum value, stop position where sufficient torque is obtained for the rotor to start rotating during forward rotation, and torque increases immediately after startup outputs excitation pattern obtained by delaying the 120 ° phase from, sufficient torque can be obtained for the rotor starts rotating in the reverse rotation, and starting straight The torque increases, the plurality of brushless motors connected in parallel, characterized in that the free-run state and stops energizing the all phases output the excitation pattern is advanced to 120 ° phase from the stop position How to start. A starting method for synchronously starting a plurality of brushless motors connected in parallel,
A rotor having a permanent magnet and a stator are obtained, and a signal obtained by combining inductances generated in respective coils of a plurality of brushless motors in which three-phase coils are wound in order in the circumferential direction on the stator to obtain the rotor Detecting a stop position of
Energizing all the phases is stopped after outputting for a certain time an excitation pattern in which the torque is sufficient to start rotation of the rotor and the torque increases immediately after startup, and the phase is delayed by 120 ° from the stop position. Steps,
A step of performing energization control based on the detected rotor position when rotor position detection by induced voltage is possible in a state where energization of all phases is stopped;
Energizing an excitation pattern with a low duty to stop rotation of each of the plurality of brushless motors when rotor position detection by induced voltage is impossible in a state where energization of all phases is stopped;
And a step of detecting the stop position of the rotor using the inductance of the coil after performing the two-phase energization locking process for stopping the rotation of the rotor. Starting method for multiple brushless motors.

Images