JP2015177697A - Driving device for brushless motor, and driving method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driving device for a brushless motor which is small-sized, reduces cost and is capable of obtaining detection accuracy of a magnetic pole position similar to 120° electrification even in low-speed rotation, and a driving method.SOLUTION: A driving device includes: a first counter which performs counting at edges of a first pulse signal and a second pulse signal when the first pulse signal and the second pulse signal are inputted from a position detection sensor for detecting a change in a magnetic flux of a sensor magnet, and resets the count when a reset signal is inputted; a rotor stop magnetic pole position estimation part for estimating a magnetic pole position of a rotor from an electrification time of an electrification pattern of a current that flows to the coil of a plurality of phases; and a rotor electrification pattern switching part which sets the magnetic pole position of the rotor estimated by the rotor stop magnetic pole position estimation part to a temporary position of the reset signal and resets the count of the first counter.

Description

  The present invention relates to a brushless motor driving apparatus and driving method.

  As drive control of a brushless motor, there is a sensorless drive method that estimates the magnetic pole position of a brushless motor by detecting an induced voltage due to the rotation of the brushless motor (Patent Document 1). However, the method described in Patent Document 1 has a problem in that, when the brushless motor is rotating at a low speed, the induced voltage generated is small, and the accuracy of detecting the magnetic pole position of the brushless motor is reduced below a predetermined number of rotations. .

  In order to solve the above-described problem, a brushless motor is provided by providing three hall elements every 120 degrees to the sensor magnet and energizing the coil based on the magnetic pole position of the brushless motor detected by the hall element. There is a way to drive.

JP 2009-71926 A

  However, in the above-described method, since three Hall elements are used, there is a problem that the cost is increased and the installation area is increased, which is an obstacle to downsizing.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a brushless device capable of obtaining the same magnetic pole position detection accuracy as when a Hall element is used even in a small size, low cost, and low rotation. To provide a motor driving device and a driving method.

  One aspect of the present invention is a brushless motor driving device including a stator having a plurality of phase coils and a rotor to which a sensor magnet having a plurality of poles in a rotational direction is fixed, and changes in magnetic flux of the sensor magnet When the first pulse signal and the second pulse signal are input from the position detection sensor that detects the above, the count is performed at the edge of the first pulse signal and the second pulse signal, and the count is performed when the reset signal is input. Estimated by a first counter to be reset, a rotor stop magnetic pole position estimation unit for estimating a magnetic pole position of the rotor from an energization time of an energization pattern of currents flowing through the coils of a plurality of phases, and the rotor stop magnetic pole position estimation unit A rotor energization power for setting the magnetic pole position of the rotor to a temporary position of the reset signal and resetting the count of the first counter. Drive device for a brushless motor having a chromatography emission switching unit.

  One embodiment of the present invention is the brushless motor driving device described above, wherein the count of the first counter is an integral multiple of a value obtained by dividing the resolution of the first counter by the number of magnetic poles of the brushless motor. The energization pattern is switched every time.

  One embodiment of the present invention is the above-described brushless motor drive device, wherein the rotor stop magnetic pole position estimation unit generates a signal that commands a current-carrying pattern of a current flowing through the coil; An inverter circuit that supplies a current to the coil by a signal from the position signal generation unit, a current measurement unit that measures a current flowing through the coil, and a current value measured using the current measurement unit are preset. A current comparison unit that outputs a detection signal when the threshold value is greater than or equal to a threshold; a second counter that counts the time from detection of the signal for instructing the energization pattern to detection of the detection signal for each energization pattern; and the energization A position estimation unit that determines a rotor stop position based on the count value counted for each pattern.

  One embodiment of the present invention is the above-described brushless motor driving device, wherein the current comparison unit is an overcurrent detection circuit that detects an overcurrent flowing through the inverter circuit.

  Another aspect of the present invention is the above-described brushless motor driving device, wherein the stator includes a three-phase coil, and an energization pattern with an electrical angle of 120 degrees ahead based on a result of the rotor stop magnetic pole position estimation unit. Is output.

  Another embodiment of the present invention is a brushless motor driving method including a stator having a coil having a plurality of phases and a rotor to which sensor magnets having a plurality of poles are fixed in a rotation direction. A first pulse signal, a second pulse signal, and a reset signal output from a position detection sensor that detects a change in magnetic flux of the sensor magnet are detected, and counted at an edge of the first pulse signal and the second pulse signal. A process of resetting the count by detecting the reset signal, and a process of estimating the magnetic pole position of the rotor from the energization time of the energization pattern of the current flowing through the coils of a plurality of phases by the rotor stop magnetic pole position estimation unit; The rotor energization pattern switching unit sets the rotor magnetic pole position estimated by the rotor stop magnetic pole position estimation unit to the temporary value of the reset signal. Set the position, and the process of resetting the count of said first counter, a method of driving a brushless motor including.

  According to the present invention, it is possible to provide a brushless motor driving apparatus and driving method capable of obtaining the same magnetic pole position detection accuracy as when a Hall element is used even in a small size, low cost, and low rotation.

It is a schematic block diagram which shows the structure of the motor system in embodiment of this invention. It is a figure which shows the structure of an inverter circuit and a current measurement part in detail. It is a figure explaining the magnetic flux and torque which generate | occur | produce with an electricity supply pattern. It is a flowchart which shows operation | movement of the drive device in embodiment of this invention. It is a timing chart for demonstrating a process when a reset signal and a stop position signal are input within the preset time. It is a timing chart for demonstrating the process when a reset signal and a stop position signal are input at a different timing.

FIG. 1 is a schematic block diagram showing a configuration of a motor system in the present embodiment. As shown in FIG. 1, the motor system includes a brushless motor 2 and a driving device 1 that controls rotational driving of the brushless motor 2.
The brushless motor 2 is a motor used for a pump for supplying hydraulic pressure and a fan for cooling the radiator. The brushless motor 2 includes a rotor having permanent magnets constituting a plurality of magnetic poles on the outer peripheral side, and coils U, V, W corresponding to three phases (U, V, W), respectively, wound in order in the rotation direction of the rotor. It is what is called an inner rotor provided with the stator which is made. Each of the coils U, V, W of each phase has one end connected to the driving device 1 via a motor terminal and the other end connected to each other.
In addition, a sensor magnet is fixed to the rotor, and is arranged at a position that is concentric with the shaft. The sensor magnet is alternately magnetized with N and S poles in the rotational direction of the rotor.

  The position detection sensor 10 is connected to the driving device 1. The position detection sensor 10 detects a change in the magnetic flux of the sensor magnet with a GMR (Giant Magneto Resistive effect) sensor. In addition, the position detection sensor 10 is, for example, a magnetic encoder that outputs the A-phase, B-phase, and Z-phase pulses to the position signal detection unit 16 in accordance with the detected change in the magnetic flux of the sensor magnet.

The A-phase pulse (hereinafter referred to as “first pulse signal”) is a rectangular wave signal in which a pulse having a predetermined pulse width is generated each time the brushless motor 2 is electrically rotated by a certain angle.
A B-phase pulse (hereinafter referred to as a “second pulse signal”) is a rectangular wave in which a pulse having a predetermined pulse width is generated each time the brushless motor 2 is electrically rotated by a certain angle, like the first pulse signal. Signal.
Further, the first pulse signal and the second pulse signal have a phase difference of an electrical angle of 90 deg, that is, a phase difference of ¼. The phases of the A-phase pulse and the B-phase pulse are reversed depending on the rotation direction of the brushless motor 2. In the present embodiment, the position detection sensor 10 outputs the first pulse signal before the second pulse signal when the brushless motor 2 rotates in the forward direction. On the other hand, when the brushless motor 2 rotates in the reverse direction, the position detection sensor 10 outputs the second pulse signal before the first pulse signal.

A Z-phase pulse (hereinafter referred to as “reset signal”) is generated by one pulse at the boundary point between the N pole and the S pole of the sensor magnet each time the electrical angle 360 deg, that is, the brushless motor 2 makes one revolution.
Since the position detection sensor 10 can detect and output the Z-phase reset signal by detecting the boundary point between the N pole and the S pole of the sensor magnet, the position detection sensor 10 can perform absolute position detection.

  The drive device 1 includes an inverter circuit 12, a shunt resistor 13, a gate driver circuit 14, an excitation signal output unit 15, and a control device 11.

FIG. 2 is a diagram showing the configuration of the inverter circuit 12 in more detail.
The inverter circuit 12 converts the DC power supplied from the power supply device 3 into AC power and applies it to the brushless motor 2. As shown in FIG. 2, the inverter circuit 12 includes six switching elements 12UH, 12UL, 12VH, 12HL, 12WH, and 12WL. The inverter circuit 12 switches the switching elements 12UH to 12WL on and off to convert DC power into AC power.

  The switching elements 12UH and 12UL connected in series, the switching elements 12VH and 12HL connected in series, and the switching elements 12WH and 12WL connected in series are connected to each other through the shunt resistor 13. It is connected in parallel between the high potential side and the ground potential. The connection point of the switching elements 12UH and 12UL is connected to one end of the coil U. The connection points of the switching elements 12VH and 12VL and the connection points of the switching elements 12WH and 12WL are connected to one end of the coil V and one end of the coil W, respectively.

  Each of the switching elements 12UH to 12WL has a configuration in which, for example, a FET (Field Effective Transistor) or an IGBT (Insulated Gate Bipolar Transistor) and a free wheel diode are connected in parallel. ing. The switching elements 12UH to 12WL are switched on and off based on a drive signal input from the excitation signal output unit 15 via the gate driver circuit 14.

  Between the inverter circuit 12 and the ground level, a shunt resistor 13 as a current measuring unit is provided. By using the shunt resistor 13, the current flowing through the inverter circuit 12, that is, the current input to the brushless motor 2 can be detected using a current comparison unit 183 (described later) of the rotor stop magnetic pole position estimation unit 18.

  The excitation signal output unit 15 receives a signal indicating the energization pattern in the inverter circuit 12 and the duty ratio in the pulse width modulation signal from the rotor stop magnetic pole position estimation unit 18. The excitation signal output unit 15 provides a signal (drive signal) for instructing switching of each of the switching elements 12UH to 12WL included in the inverter circuit 12 based on the signal input from the rotor stop magnetic pole position estimation unit 18. And output to the inverter circuit 12 via the gate driver circuit 14.

The control device 11 includes a rotor stop magnetic pole position estimation unit 18, a position signal detection unit 16, rotor energization, and a rotor energization pattern switching unit 17.
The control device 11 controls the start of the brushless motor 2 based on an operation command input from the outside. Specifically, the control device 11 controls the brushless motor 2 in the order of stop magnetic pole position detection control, stop magnetic pole position fixing control, and drive control based on the operation command. The stop magnetic pole position detection control is control for detecting the stop position (magnetic pole position) of the rotor of the brushless motor 2. The stop magnetic pole position fixing control is control for fixing the rotor position detected by the stop magnetic pole position detection control. The drive control is control for driving the brushless motor 2 from the stop position of the rotor fixed by the stop magnetic pole position fixing control. Details of the above-described start control of the brushless motor 2 will be described later. Note that the control device 11 may be configured using a CPU, a memory, or the like, and cause the CPU to execute a program stored in the memory so as to operate as each functional unit.

  In the rotor stop magnetic pole position estimation unit 18, the control device 11 performs the above-described stop magnetic pole position detection control and stop magnetic pole position fixing control. Further, the control device 11 drives the brushless motor 2 from the rotor stop position fixed by the stop magnetic pole position fixing control by the rotor stop magnetic pole position estimation unit 18, the rotor energization pattern switching unit 17, and the position signal detection unit 16. Control. Hereinafter, stop magnetic pole position detection control, stop magnetic pole position fixing control, and drive control will be described in order.

<Stopping magnetic pole position detection control>
When the rotor stop magnetic pole position estimation unit 18 receives an operation command from the outside, the rotor stop magnetic pole position estimation unit 18 performs stop magnetic pole position detection control. The stop magnetic pole position detection control will be described below.
The rotor stop magnetic pole position estimation unit 18 includes a position signal generation unit 181, a current measurement unit 182, a current comparison unit 183, a current application time measurement unit 184, and a position estimation unit 185.

When an operation command is input from the outside, the position signal generation unit 181 supplies the excitation signal output unit 15 with six predetermined stop position determination energization patterns that are continued for a period of time that the rotor does not rotate. Issue a command. Note that the time during which the rotor does not rotate varies depending on the inertia of the brushless motor 2, but is, for example, between a few microseconds and a few milliseconds. Accordingly, the excitation signal output unit 15 outputs a pulse width modulation signal, which is a drive signal corresponding to the energization pattern, to the inverter circuit 12, and the switching elements 12UH to 12WL are turned ON / OFF corresponding to the pulse width modulation signal. Power is supplied to any two of the three phases.
In addition, when the position signal generation unit 181 receives a signal from the current application time measurement unit 184, the position signal generation unit 181 outputs a signal to instruct the next energization pattern to the excitation signal output unit 15.

FIG. 3 is a diagram showing an energization pattern for determining a stop position where the position signal generator 181 issues a command. In FIG. 3, the energization patterns # 1 to # 6 are patterns that can drive the brushless motor 2.
In the energization pattern # 1, a current flows from the U-phase coil U to the V-phase coil V. The U phase is N pole magnetized and the V phase is S pole magnetized.
In the energization pattern # 2, a current flows from the U phase to the W phase coil W. U phase is N pole magnetized, W
The phase is south pole magnetized.
In the energization 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.
In the energization 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.
In the energization 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.
In the energization 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.

  Returning to FIG. 2, the current comparison unit 183 has a comparator, and the reference voltage is input to the positive input terminal of the comparator, and the voltage of the shunt resistor 13 is input to the negative terminal. ing. That is, when the voltage generated by the current flowing through the shunt resistor 13 reaches the reference potential, the current comparison unit 183 outputs an overcurrent detection signal to the current application time measurement unit 184. When the current comparison unit 183 outputs an overcurrent detection signal to the current application time measurement unit 184, the rotor stop magnetic pole position estimation unit 18 stops outputting a signal indicating the energization pattern to the excitation signal output unit 15. . Therefore, the current comparison unit 183 is an overcurrent detection circuit that detects an overcurrent flowing through the inverter circuit 12.

Returning to FIG. 1, the current application time measurement unit 184 includes a second counter 184A and a storage unit 184B.
The second counter 184A starts measuring time when the position signal generator 181 outputs a signal for instructing an energization pattern. Further, the second counter 184A stops timing when it detects the overcurrent detection signal supplied from the current comparator 183. That is, the second counter 184A measures the time from when the signal that commands the energization pattern is output until the overcurrent detection signal is detected.

  When the overcurrent detection signal is input to the current application time measurement unit 184, the storage unit 184B stores the count value (timed value) of the second counter 184A. The second counter 184A resets the count value counted after a predetermined time has elapsed, and simultaneously outputs a signal to the position signal generator 181.

  The position estimation unit 185 acquires the count value stored in the storage unit 184B for each energization pattern described above. The position estimation unit 185 estimates a position where the rotor is stopped at the rotor position of the energization pattern corresponding to the minimum energization time among the measurement times (count values) corresponding to the respective energization patterns. When estimating the rotor stop position, the position estimation unit 185 outputs a control signal to the rotor energization pattern switching unit 17.

Next, stop magnetic pole position fixing control will be described.
<Stopping magnetic pole position fixing control>
The rotor stop magnetic pole position estimation unit 18 outputs a signal indicating an energization pattern corresponding to the rotor stop position estimated by the position estimation unit 185 to the excitation signal output unit 15 for a certain period of time. As a result, the drive device 1 can position the rotor by drawing the rotor into the position of the rotor corresponding to the energization pattern estimated by the position estimation unit 185.

Next, drive control will be described.
<Drive control>
The rotor stop magnetic pole position estimation unit 18 selects an energization pattern that is advanced by 120 ° in the rotation direction of the brushless motor 2 from the energization pattern estimated by the position estimation unit 185 as an energization pattern at the time of start. This is because if the energization pattern is implemented by advancing the phase by 120 ° from the phase of the rotor stop position in the rotational direction, the rotor can be rotated in the forward rotation direction with the maximum torque.

The position signal detection unit 16 includes a first counter 161, a rotation direction determination unit 162, and a rotation speed determination unit 163.
The first counter 161 receives the first pulse signal, the second pulse signal, and the reset signal supplied from the position detection sensor 10. The first counter 161 counts at each edge of the first pulse signal and the second pulse signal. For example, the first counter 161 increments the count value at each edge of the first pulse signal and the second pulse signal. When the reset signal is input, the first counter 161 resets the count values of the first pulse signal and the second pulse signal to zero.

  Further, when a signal indicating the stop position of the rotor (hereinafter referred to as “stop position signal”) is supplied from the rotor energization pattern switching unit 17, the first counter 161 is the same as when a reset signal is input. The count values of the first pulse signal and the second pulse signal are reset to zero. That is, the first counter 161 uses the stop position signal as a pseudo reset signal (hereinafter referred to as “pseudo reset signal”) and resets the count value to zero.

The rotation direction determination unit 162 determines the rotation direction of the brushless motor 2 based on which of the first pulse signal and the second pulse signal is input to the first counter 161 first.
The rotation speed determination unit 163 calculates the rotation speed from the gradient of the change in the counter value of the first counter 161. Further, the rotation speed determination unit 163 determines whether or not the calculated rotation speed is less than a predetermined threshold value.

The rotor energization pattern switching unit 17 is connected to the first counter 161 and the rotor stop magnetic pole position estimation unit 18. In the rotor energization pattern switching unit 17, the count of the first counter 161 is an integral multiple of a value obtained by dividing the resolution of the first counter 161 by the number of magnetic poles of the brushless motor 2 (hereinafter referred to as “energization pattern switching value”). Each time, the signal for switching the energization pattern (hereinafter referred to as “energization switching signal”) is output to the rotor stop magnetic pole position estimation unit 18. For example, the first counter 161 is nbit ^{(n 2} counts), when the number of magnetic poles of the brushless motor 2 is 6, the energization pattern switching interval ^{becomes n} 2/6 counts. Thus, the rotor energization pattern switching unit 17 outputs the energization switching signal every first counter 161 counts the integer multiple of n ^2/6 to the rotor stop magnetic pole position estimation unit 18. However, in the case of an integer that is an integral multiple, the number of magnetic poles described above is the maximum value. In the case where n ^2/6 is not divisible, it may be rounded up to the decimal point.

  Further, when the rotor energization pattern switching unit 17 receives the control signal supplied from the position estimation unit 185, the rotor energization pattern switching unit 17 transmits a stop position signal indicating the stop position of the rotor to the first counter 161.

Next, the operation of the driving device 1 in this embodiment will be described. FIG. 4 is a flowchart showing the operation of the drive device according to this embodiment.
When the brushless motor 2 is started, there are a case where the brushless motor 2 is stopped and a case where the brushless motor 2 is started from a state where the brushless motor 2 is rotated by an external force. For example, when the brushless motor 2 is used as a radiator fan rotation mechanism, when the air is moving in the direction from the radiator toward the engine room (for example, when the vehicle is moving forward), the radiator fan is rotated forward without being energized. Thus, the brushless motor 2 is also rotated forward. On the other hand, when the air is moving from the engine side toward the radiator (for example, when the vehicle is moving backward), the brushless motor 2 may rotate in the reverse direction. The operation of the driving device 1 in the present embodiment differs in the starting method depending on whether the brushless motor 2 is stopped or rotating. Therefore, the drive device 1 in the present embodiment determines whether or not the brushless motor 2 is stopped in step S101.

  In step S101, when receiving an operation command from the outside, the control device 11 determines whether or not the brushless motor 2 is stopped. When the first counter 161 detects at least one of the first pulse signal, the second pulse signal, and the reset signal in the first counter 161 (step S101: NO), the brushless motor 2 is rotating. And the process proceeds to step S103. On the other hand, when the control device 11 does not detect any of the first pulse signal, the second pulse signal, and the reset signal in the first counter 161 (step S101: YES), the brushless motor 2 is stopped. And the process proceeds to step S107.

  In step S103, when the rotation direction determination unit 162 detects the first pulse signal before the second pulse signal by the first counter 161 (step S103: YES), the brushless motor 2 rotates in the forward rotation direction. And the process proceeds to step S105. On the other hand, when the first counter 161 detects the second pulse signal before the first pulse signal (step S103: NO), the rotation direction determination unit 162 determines that the brushless motor 2 is rotating in the reverse direction. Determine and proceed to step S104.

In step S104, the control device 11 stops the brushless motor 2 and restarts itself.
In step S <b> 105, the rotation speed determination unit 163 calculates the rotation speed from the inclination of the change in the counter value of the first counter 161. Further, when the calculated rotation speed exceeds the threshold value (step S105: YES), the rotation speed determination unit 163 proceeds to step S106. On the other hand, when the calculated rotation speed is less than the threshold (step S105: NO), the rotation speed determination unit 163 proceeds to step S104. Here, the threshold value is a value of a rotation speed sufficient for the brushless motor 2 to make one rotation within a certain time. Within a certain period of time is a time that is a time-out for shifting from the processing of step S103, step S104, and step S106 to the processing of step S104.

  In step 106, when the first counter 161 detects a reset signal in step 106 (step S106: YES), the control device 11 proceeds to step S114. On the other hand, when the first counter 161 does not detect the reset signal (step S106: NO), the control device 11 proceeds to step S103.

In step S107, the control device 11 performs stop magnetic pole position detection control, and proceeds to step S108.
In step S108, the control device 11 performs stop magnetic pole position fixing control, and proceeds to step S109.

In step S <b> 109, when the rotor energization pattern switching unit 17 receives the control signal supplied from the position estimation unit 185, it outputs a stop position signal to the first counter 161. The first counter 161 receives the stop position signal supplied from the rotor energization pattern switching unit 17. The first counter 161 sets the stop position signal as a pseudo reset signal and resets the counter value to zero.

  In step S110, the rotor stop magnetic pole position estimation unit 18 selects an energization pattern in which a phase of 120 ° is advanced in the rotation direction of the brushless motor 2 from the energization pattern estimated by the position estimation unit 185 as a start-up energization pattern. Further, the rotor stop magnetic pole position estimation unit 18 outputs a signal indicating the selected energization pattern and a signal indicating a predetermined duty ratio to the excitation signal output unit 15. The excitation signal output unit 15 outputs a signal instructing switching of each of the switching elements 12UH to 12WL included in the inverter circuit 12 to on and off to the inverter circuit 12 via the gate driver circuit 14 to drive the brushless motor 2. To do.

  In step S111, the control device 11 determines whether or not the first counter 161 has detected a reset signal. When the first counter 161 detects the reset signal, that is, when the reset signal and the stop position signal are detected at substantially the same timing (step S111: YES), the control device 11 proceeds to step S114. On the other hand, if the first counter 161 does not detect the reset signal, that is, if the reset signal is not detected at the same timing as the stop position signal (step S111: NO), the control device 11 proceeds to step S112.

  In step S114, the first counter 161 counts the first pulse signal and the second pulse signal based on the reset signal. FIG. 5 is a timing chart for explaining processing when the reset signal and the stop position signal are input to the first counter 161 within a preset time. FIG. 5A shows a current waveform flowing through the shunt resistor, the vertical axis shows the current flowing through the shunt resistor, and the horizontal axis shows time. FIG. 5B shows the count value of the first counter 161, the vertical axis shows the count value, and the horizontal axis shows the time. FIG. 5C shows the timing of the reset signal detected by the first counter 161, where the vertical axis shows voltage and the horizontal axis shows time. An arrow A indicates resetting of the counter value by the stop position signal.

Rotor energization pattern switching unit 17 counts of the first counter 161, each time an integral multiple of the energization pattern switching value (n ^2/6), and outputs the energization switching signals to the rotor stop magnetic pole position estimation unit 18 ( FIG. 5B). When receiving the energization switching signal supplied from the rotor energization pattern switching unit 17, the rotor stop magnetic pole position estimation unit 18 transmits a signal indicating the next energization pattern to the excitation signal output unit 15 to switch the energization pattern. For example, when the first counter 161 is 10 bits (1024 counts) and the number of magnetic poles of the brushless motor 2 is 6, the energization pattern switching interval is 170 counts. The rotor energization pattern switching unit 17 outputs an energization switching signal to the rotor stop magnetic pole position estimation unit 18 every time the first counter 161 counts 170 (FIG. 5A). In addition, when the energization pattern is switched six times, the rotor rotates once, so the first counter 161 detects a reset signal (FIG. 5C). Therefore, when the first counter 161 detects the reset signal, the first counter 161 resets the counter value to zero. Then, the first counter 161 again counts the first pulse signal and the second pulse signal based on the reset signal.

  In step S112, the first counter 161 counts the first pulse signal and the second pulse signal based on the reset signal. FIG. 6 is a timing chart for explaining processing when the reset signal and the stop position signal are input to the first counter 161 at different timings. FIG. 6A shows a current waveform flowing through the shunt resistor, the vertical axis indicates the current flowing through the shunt resistor, and the horizontal axis indicates time. FIG. 6B shows the count value of the first counter 161, where the vertical axis indicates the count value and the horizontal axis indicates time. FIG. 6C shows the timing of the reset signal input to the first counter 161, where the vertical axis shows voltage and the horizontal axis shows time. An arrow B indicates resetting of the counter value by the stop position signal.

Rotor energization pattern switching unit 17 determines the first counter value whether elapsed ^{(n 2/6) × m} . That is, the rotor energization pattern switching unit 17 determines whether or not the count of the first counter 161 has passed an integral multiple of the energization pattern switching value. Here, the maximum value of m indicates the number of magnetic poles.

Rotor energization pattern switching unit 17, when the counter value has exceeded the ^{(n 2/6) × m} ( step S112: YES), the process proceeds to step S113.
The rotor energization pattern switching unit 17, when the first counter value ⁽ⁿ 2/6) has not passed × m (step S112: NO), the process proceeds to step S111.

  In step S <b> 113, the rotor energization pattern switching unit 17 outputs an energization switching signal to the rotor stop magnetic pole position estimation unit 18. Upon receiving the energization switching signal supplied from the rotor energization pattern switching unit 17, the rotor stop magnetic pole position estimation unit 18 transmits a signal indicating the next energization pattern to the excitation signal output unit 15 to switch the energization pattern (FIG. 6). (B)). When the energization pattern is switched, the control device 11 proceeds to step S111. That is, when the first counter 161 does not receive the reset signal, the first counter 161 counts the first pulse signal and the second pulse signal based on the stop position signal, and switches the energization pattern according to the count value.

In step S111, as indicated by an arrow C in FIG. 6B, the first counter 161 receives a reset signal, for example, at a position where the electrical angle is advanced by 150 degrees (FIG. 6C). Reset the value to zero. In addition, the rotor energization pattern switching unit 17 outputs an energization switching signal to the rotor stop magnetic pole position estimation unit 18 to change the energization pattern (FIG. 6A). Thus, as described above, in step S111, the first counter 161 changes the signal for resetting the counter value to zero from the stop position signal to the reset signal, and the first pulse signal and the second pulse are based on the reset signal. Count the signal. The rotor energization pattern switching section 17, each time an integral multiple of the energization pattern switching value (n ^2/6), and outputs the energization switching signals to the rotor stop magnetic pole position estimation unit 18, switches the energization pattern

  As described above, according to the present embodiment, when the magnetic pole position is detected using the position detection sensor 10, the drive device 1 is energized in six ways for each electrical angle of 60 degrees when starting the brushless motor 2. The pattern is energized, and the motor phase current is detected as a voltage using the shunt resistor 13. Further, the rotor stop magnetic pole position estimation unit 18 measures the energization time from the time when the energization is started until the time when the detected voltage matches a certain threshold value in each energization pattern. Further, the rotor stop magnetic pole position estimating unit 18 turns off the energization of the brushless motor 2 and starts energizing the next energization pattern when the detected voltage matches a certain threshold value.

  The rotor stop magnetic pole position estimation unit 18 acquires the energization time of the above six energization patterns, and sets the energization pattern that is the shortest of the energization times as the position where the rotor is stopped. . Further, the rotor energization pattern switching unit 17 transmits a stop position signal to the first counter 161 when the rotor stop magnetic pole position estimation unit 18 estimates the position where the rotor is stopped. When receiving the stop position signal, the first counter 161 resets the counter value to zero using the stop position signal as a pseudo reset signal. That is, when the reset signal is not input to the first counter 161 and the absolute value of the rotor is unclear, the driving device 1 temporarily sets the stop position of the rotor until the reset signal is received. Set to the provisional position. Thereby, the drive device 1 can detect the magnetic pole position by the pseudo reset signal even without the reset signal. Therefore, since an encoder that is smaller and less expensive than the Hall element can be used as the magnetic pole position sensor, it is possible to perform control excellent in detection performance of the magnetic pole position at a small size and at low cost.

  In addition, as described above, according to the present embodiment, the driving device 1 determines that the count of the first counter 161 is a value obtained by dividing the resolution of the first counter 161 by the number of magnetic poles of the brushless motor 2 (energization pattern switching). The energization pattern is switched every time the value is an integral multiple of (value). Thereby, the energization of the brushless motor 2 can be switched based on the resolution of the first counter.

  Further, as described above, according to the present embodiment, the rotor stop position is detected by comparing the time until the current flowing through the coil becomes equal to or greater than the predetermined threshold for each energization pattern. The position can be measured with high accuracy. Further, a complicated circuit is not required, and the apparatus configuration can be simplified.

  As described above, according to the present embodiment, the driving device 1 detects the overcurrent flowing through the inverter circuit 12 in the current comparison unit 183 and controls the current flowing through the inverter according to the detection result. Thereby, the brushless motor 2 can be controlled without causing an overcurrent to flow through the brushless motor 2.

  Further, as described above, according to the present embodiment, in the system in which the brushless motor 2 is always stopped when the power is turned off and the power supply to the position detection sensor 10 is turned off, the driving device 11 turns on the power again. Supplied. At this time, the drive device 11 can perform stop magnetic pole position detection control and detect the magnetic pole position with reference to the magnetic pole stop position, so that the battery backup function of the drive device 11 can be made unnecessary.

  Further, as described above, according to the present embodiment, in the system in which the brushless motor 2 is rotated by an external force when the power is turned off, the position detection sensor 10 is supplied with power again after the power supply is stopped. . At that time, the driving device 1 detects the rotation speed and the rotation direction of the brushless motor 2 when the first counter 161 counts up or down in a certain direction. The drive device 11 determines that the brushless motor 2 is rotating, provides a period of waiting for a reset signal for a certain period of time, and can drive the brushless motor 2 when the reset signal is detected, so that the battery of the drive device 11 is backed up. Functions can be eliminated.

The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes designs and the like that do not depart from the gist of the present invention.
In the embodiment described above, the drive device 11 performs the control of the brushless motor 2 in the order of the stop magnetic pole position detection control, the stop magnetic pole position fixing control, and the drive control based on the operation command, but is not limited thereto. For example, the drive device 11 can omit the stop magnetic pole position fixing control.

  Further, in the above-described embodiment, the drive device 11 estimates the magnetic pole position by the stop magnetic pole position detection control, pulls the rotor into the magnetic pole position estimated by the stop magnetic pole position fixing control, and positions the rotor. Not. For example, the drive device 11 may omit the stop magnetic pole position detection control, select an arbitrary energization pattern, perform two-phase lock energization with the selected energization pattern, and fix the magnetic pole position. Further, this magnetic pole position may be set to the temporary position of the reset signal described above.

  In the above-described embodiment, the position detection sensor 10 outputs the first pulse signal, the second pulse signal, and the reset signal to the control device 11 as a rectangular wave, but is not limited thereto. For example, the position detection sensor 10 may count at each edge of the first pulse signal, the second pulse signal, and the reset signal, convert the count value from digital to analog, and output the digital value to the control device 11. Further, the position detection sensor 10 may output a counter value to the control device 11 at regular intervals by serial communication.

DESCRIPTION OF SYMBOLS 1 Drive apparatus 2 Brushless motor 10 Position detection sensor 11 Control apparatus 12 Inverter circuit 13 Shunt resistor 14 Gate driver circuit 15 Excitation signal output part 16 Position signal detection part 17 Rotor energization pattern switching part 18 Rotor stop magnetic pole position estimation part 161 1st Counter 162 Rotation direction determination unit 163 Rotation speed determination unit 181 Position signal generation unit 183 Current comparison unit 184 Current application time measurement unit 184A Second counter 184B Storage unit 185 Position estimation unit 12UH, 12UL, 12VH, 12VL, 12WH, 12WL Switching element

Claims (6)

A brushless motor driving device comprising: a stator having a coil of a plurality of phases; and a rotor to which a sensor magnet having a plurality of poles is fixed in a rotation direction.
When a first pulse signal and a second pulse signal are input from a position detection sensor that detects a change in magnetic flux of the sensor magnet, the count is detected at the edge of the first pulse signal and the second pulse signal, and a reset signal A first counter that resets the count when
A rotor stop magnetic pole position estimator for estimating the magnetic pole position of the rotor from the energization time of the energization pattern of the current flowing through the coils of a plurality of phases;
A rotor energization pattern switching unit that sets the magnetic pole position of the rotor estimated by the rotor stop magnetic pole position estimation unit to a temporary position of the reset signal, and resets the count of the first counter;
A brushless motor drive device having   2. The brushless motor driving device according to claim 1, wherein the energization pattern is switched each time the count of the first counter becomes an integral multiple of a value obtained by dividing the resolution of the first counter by the number of magnetic poles of the brushless motor. The rotor stop magnetic pole position estimation unit is
A position signal generator for generating a signal for instructing an energization pattern of a current flowing through the coil;
An inverter circuit for supplying a current to the coil by a signal from the position signal generator;
A current measuring unit for measuring a current flowing through the coil;
A current comparison unit that outputs a detection signal when a current value measured using the current measurement unit is greater than or equal to a preset threshold; and
A second counter that counts the time from detection of the energization pattern to the detection of the detection signal for each energization pattern;
A position estimation unit for determining a rotor stop position from the magnitude of the count value counted for each energization pattern;
The brushless motor drive device according to claim 1, comprising:   4. The brushless motor driving apparatus according to claim 3, wherein the current comparison unit is an overcurrent detection circuit that detects an overcurrent flowing through the inverter circuit.   The brushless motor according to any one of claims 1 to 4, wherein the stator is composed of a three-phase coil, and outputs an energization pattern with an electrical angle of 120 degrees ahead based on a result of the rotor stop magnetic pole position estimation unit. Drive device. A method for driving a brushless motor, comprising: a stator having coils of a plurality of phases; and a rotor to which sensor magnets having a plurality of poles are fixed in the rotational direction.
A first counter detects a first pulse signal, a second pulse signal, and a reset signal output from a position detection sensor that detects a change in magnetic flux of the sensor magnet, and the first pulse signal and the second pulse signal are detected. A process of resetting the count by detecting the reset signal,
A process of estimating the magnetic pole position of the rotor from the energization time of the energization pattern of the current flowing through the coils of a plurality of phases by the rotor stop magnetic pole position estimation unit;
A process in which a rotor energization pattern switching unit sets the rotor magnetic pole position estimated by the rotor stop magnetic pole position estimation unit to a temporary position of the reset signal, and resets the count of the first counter;
Method for driving a brushless motor including

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