JP6673092B2 - Drive - Google Patents

Description

  The present invention relates to a driving device for driving a brushless motor.

  Conventionally, a controller for a brushless motor as described in Patent Document 1 has been known. The controller includes a control circuit and a drive circuit. The control circuit detects an induced voltage generated in a non-conducting phase coil in the stator of the brushless motor. Then, the control circuit detects the rotational position of the rotor based on the induced voltage, and performs the induced drive for operating the drive circuit according to the detected rotational position.

  Note that the induced voltage of the coil is generated only when the rotor is rotating. Therefore, the control circuit performs an initial drive for operating the drive circuit regardless of the rotational position of the rotor before performing the induction drive. When the control circuit detects the zero cross of the induced voltage in the initial drive, the control circuit starts the induced drive.

  By the way, when the control circuit starts the rotation of the rotor, the rotor may not easily move depending on the relative position of the rotor with respect to the coil of the energized phase. On the other hand, the control circuit performs an initial setting for moving the rotor so that the rotor does not move to a position where it is difficult to move at the start of rotation. After performing the initial setting, the control circuit performs the initial driving and performs the induction driving.

JP 2011-72057 A

  However, in the above configuration, the initial setting by the control circuit may increase the time required to start the induced driving. That is, there is a possibility that the start-up time of the brushless motor becomes longer. On the other hand, in the configuration in which the control circuit does not perform the initial setting, not only the time until the start of the induction drive is increased but also the induction voltage may not be generated in the coil depending on the position of the rotor. There is a possibility that the motor cannot be started.

  The present invention has been made in view of such a problem, and an object of the present invention is to provide a drive device capable of shortening a start-up time of a brushless motor.

  The present invention employs the following technical means to achieve the above object. In addition, the code | symbol in a parenthesis shows the correspondence with the specific means in the following embodiment as one aspect, and does not limit a technical range.

One of the present inventions
A drive device for driving a brushless motor (200) having a stator (210) having a plurality of coils (212) and a rotor rotatable relative to the stator,
A position detection unit (14) that detects a rotation position of the rotor based on an induced voltage generated in a non-energized phase coil when the rotor is rotating and outputs a position detection signal;
At the start of energization of the coil, the rotor is rotated by energizing the coil to perform initial drive control for causing the position detection unit to detect the rotational position, and by controlling energization of the coil based on the detected position detection signal, An energization control unit (16, 18, 20) for performing induction drive control for rotating the rotor according to the induced voltage;
A current detector (30) for detecting a current flowing through the coil and outputting a current detection signal;
An overcurrent determination unit (32) for determining whether or not an overcurrent is flowing through the coil based on the current detection signal;
In the initial drive control, the energization control unit switches the energization phase of the coil when it is determined that overcurrent is flowing through the coil due to energization ,
In the initial drive control, the energization control unit energizes the coil by Duty control, and increases the Duty value as time elapses from the start of energization .

  If the rotor does not rotate even though the coil is energized, the impedance of the coil becomes small and an overcurrent flows through the coil. On the other hand, in the above configuration, when an overcurrent flows through the coil due to energization in the initial drive control, the energization control unit determines that the rotor is not rotating according to the relative position of the energized phase to the coil, Is switched. The energization control unit can change the relative position of the rotor with respect to the energized phase coil by switching the energized phase of the coil.

  Thus, it is possible to prevent the rotor from rotating in accordance with the position of the energized phase relative to the coil. According to the above, the driving device can start the brushless motor without performing the initial setting. Therefore, the startup time of the brushless motor can be shortened.

FIG. 2 is a circuit diagram illustrating a schematic configuration of a driving device according to the first embodiment. 5 is a flowchart illustrating a processing procedure of initial drive control. It is a flowchart which shows the processing procedure of induction drive control. 9 is a timing chart in a case where a position detection unit normally specifies a rotation position of a rotor in the induced drive control. 9 is a timing chart in a case where the position detection unit erroneously specifies the rotational position of the rotor in the induced drive control. 5 is a timing chart in a case where a position detection unit specifies a rotational position of a rotor during a power supply stop period in the induced drive control.

  This will be described with reference to the drawings. In addition, in several embodiments, the same code | symbol shall be attached | subjected to a common element or a related element.

(1st Embodiment)
First, a schematic configuration of a brushless motor 200 and a driving device 100 that drives the brushless motor 200 will be described with reference to FIG.

  The brushless motor 200 has a stator 210 and a rotor (not shown) configured to be rotatable relative to the stator. Stator 210 has a plurality of coils 212. In the present embodiment, the stator 210 has, as the coil 212, a U-phase coil 212a, a W-phase coil 212c, and a W-phase coil 212c. The rotor is a magnet rotor.

  The brushless motor 200 can be applied to, for example, a drive source of a fuel pump. That is, the driving device 100 can be applied to an electronic device that controls the operation of the fuel pump by controlling the operation of the brushless motor 200.

  The driving device 100 includes a neutral point voltage generator 10, a plurality of comparators 12, a position detector 14, an energization pattern generator 16, a duty calculator 18, a PWM output unit 20, an inverter circuit 22, a shunt resistor 30, and an A current determination unit 32 is provided. The drive device 100 does not include a sensor for detecting the rotational position of the rotor. Therefore, the driving device 100 drives the brushless motor 200 by a sensorless driving method.

  The neutral point voltage generation unit 10 generates a voltage corresponding to the neutral point voltage based on the terminal voltages of the coils 212 of each phase in the stator 210. The neutral point voltage is a voltage at a neutral point which is a common connection point of the coils 212. Hereinafter, the voltage generated by the neutral point voltage generator 10 is referred to as a neutral point equivalent voltage. The neutral point voltage generator 10 is connected to terminals of the coils 212 of each phase in the stator 210. The neutral point equivalent voltage generated by the neutral point voltage generation unit 10 is input to each comparator 12.

  The comparator 12 outputs a signal for the position detection unit 14 to specify an induced voltage generated in the coil 212 of each phase. The driving device 100 includes, as the comparator 12, a U-phase comparator 12a, a V-phase comparator 12b, and a W-phase comparator 12c.

  The U-phase comparator 12a is connected to a terminal of the U-phase coil 212a in the stator 210, and compares a terminal voltage of the U-phase coil 212a with a voltage corresponding to a neutral point. V-phase comparator 12b is connected to the terminal of V-phase coil 212b in stator 210, and compares the terminal voltage of V-phase coil 212b with the voltage corresponding to the neutral point. The W-phase comparator 12c is connected to a terminal of the W-phase coil 212c in the stator 210, and compares the terminal voltage of the W-phase coil 212c with a voltage corresponding to a neutral point.

  Each comparator 12 outputs an output signal to the position detection unit 14 in accordance with the result of comparison between the terminal voltage of the connected coil 212 and the voltage corresponding to the neutral point. The level of the output signal of the comparator 12 is set to High or Low according to the magnitude relationship between the terminal voltage and the voltage corresponding to the neutral point.

  When the rotor is rotating, the terminal voltage of the coil 212 in the non-energized phase generates an induced voltage every time the rotor rotates a predetermined angle. Each time an induced voltage is generated in the terminal voltage of the coil 212, the terminal voltage changes so as to straddle the neutral point voltage. The timing at which the terminal voltage crosses the neutral point voltage is the zero-cross timing.

  When the brushless motor 200 is driven by the 120-degree energization method, each coil 212 repeats energization of 120 degrees in electrical angle and non-energization of 60 degrees in order. In this case, during the non-energized period of 60 degrees in the coil 212, the magnitude relationship between the terminal voltage and the voltage corresponding to the neutral point is reversed, and the level of the output signal of the comparator 12 changes. According to this, except for a period in which the following spike noise is generated, the output signal of the comparator 12 repeatedly falls and rises in order every time the rotor rotates 180 electrical degrees.

  The position detector 14 specifies the rotational position of the rotor based on the output signal of each comparator 12. More specifically, the position detector 14 detects whether an induced voltage is generated in the terminal voltage of the coil 212 and the rotational position of the rotor based on at least one of the rising edge and the falling edge of the output signal of the comparator 12. I do.

  The position detection unit 14 generates a position detection signal corresponding to the rotational position of the rotor, and outputs the generated position detection signal to the energization pattern generation unit 16 and the duty calculation unit 18. The position detection signal is a signal whose value changes each time the position detection unit 14 specifies the induced voltage. That is, the position detection signal indicates whether or not the position detection unit 14 has specified the rotational position of the rotor.

  The energization pattern generation unit 16 generates and outputs an energization pattern to the three-phase coils 212 of the stator 210. The energization pattern is a signal including which phase of the three-phase coils 212 of the stator 210 is to be the energization phase and the energization timing of each phase. The energization pattern generation unit 16 generates an energization pattern based on the timing at which the position detection signal changes. The energization pattern generator 16 outputs the energization pattern to the PWM output unit 20.

  The Duty calculator 18 calculates a Duty value. The duty value is used when the PWM output unit 20 performs duty control on the inverter circuit 22. The Duty value can also be called a Duty ratio. The duty calculation unit 18 calculates the current value of the rotation speed of the rotor based on the position detection signal. In addition, the target value of the rotation speed of the rotor is predetermined to the duty calculation unit 18 or is input from outside. The duty calculation unit 18 calculates a duty value based on a difference between the current value of the rotor rotation speed and the target value. Then, the duty calculation unit 18 outputs the calculated duty value to the PWM output unit 20.

  The PWM output unit 20 outputs a PWM signal to the inverter circuit 22. That is, the PWM output unit 20 performs duty control on the inverter circuit 22. The PWM output unit 20 generates a PWM signal by synthesizing the energization pattern and the Duty value.

  The inverter circuit 22 has three element modules 24. More specifically, the inverter circuit 22 has, as the element modules 24, a U-phase element module 24a, a V-phase element module 24b, and a W-phase element module 24c.

  Each element module 24 has two N-channel type MOSFETs 26a and 26b and diodes 28a and 28b connected in series. The drain of each MOSFET 26a is connected to a battery. The source of each MOSFET 26b is grounded via a shunt resistor 30. Diodes 28a and 28b are connected between the drain and the source of each of the MOSFETs 26a and 26b. A common connection point of the MOSFETs 26 a and 26 b is an output terminal of the inverter circuit 22 and is connected to a terminal of each phase coil 212 in the stator 210.

  The gates of the MOSFETs 26a and 26b are connected to the PWM output unit 20. The MOSFETs 26a and 26b perform on / off operations according to the PWM signal. The energized phase and the non-energized phase of the coil 212 are determined according to the on / off operation of the MOSFETs 26a and 26b. The energization pattern generation unit 16, the duty calculation unit 18, and the inverter circuit 22 correspond to an energization control unit described in the claims.

  When the brushless motor 200 is started, the drive device 100 performs initial drive control independent of the rotational position of the rotor. In the initial drive, the driving device 100 rotates the rotor, monitors the terminal voltage of the coil 212 in the non-energized phase, and specifies the induced voltage. As a result, the driving device 100 detects the rotational position of the rotor. When detecting the rotational position of the rotor, the drive device 100 ends the initial drive control and performs the induced drive control for controlling the energization of the coil 212 according to the detected rotational position of the rotor. Specific processing procedures of the initial drive control and the induced drive control will be described in detail below.

  The shunt resistor 30 is arranged to detect a current flowing through the coil 212. The shunt resistor 30 is arranged between the common connection point of the sources in each MOSFET 26b and the ground. When the coil 212 is energized, the current flowing through the coil 212 in the energized phase also flows through the shunt resistor 30. That is, the voltage across the shunt resistor 30 corresponds to the value of the current flowing through the coil. The shunt resistor 30 corresponds to a current detection unit described in the claims. The voltage across the shunt resistor 30 corresponds to the current detection signal described in the claims.

  The overcurrent determining unit 32 determines whether an overcurrent is flowing through the coil 212. The overcurrent determination unit 32 compares the voltage between both ends of the shunt resistor 30 with a preset threshold. The overcurrent determining unit 32 determines that an overcurrent is flowing through the coil 212 when the voltage across the shunt resistor 30 exceeds the threshold.

  The overcurrent determination unit 32 outputs a determination result as to whether an overcurrent is flowing through the coil 212 to the energization pattern generation unit 16 and the PWM output unit 20. The energization pattern generation unit 16 changes the energization pattern according to the determination result of the overcurrent determination unit 32. In addition, the PWM output unit 20 determines the energized phase and the non-energized phase of the coil 212 according to the determination result of the overcurrent determination unit 32.

  The position detection unit 14, the conduction pattern generation unit 16, the duty calculation unit 18, the PWM output unit 20, and the overcurrent determination unit 32 are configured by, for example, a microcomputer. In other words, each of the position detection unit 14, the conduction pattern generation unit 16, the duty calculation unit 18, the PWM output unit 20, and the overcurrent determination unit 32 is a part of the microcomputer.

  Next, a processing procedure of the initial drive control will be described with reference to FIG.

  The drive device 100 starts the initial drive control when the rotation of the rotor is started, that is, when the brushless motor 200 is started. In the initial drive control, first, the Duty calculator 18 initializes the Duty value (S10). That is, the duty calculation unit 18 sets the duty value to a preset initial value. Then, the duty calculation unit 18 outputs the initialized duty value to the PWM output unit 20.

  Then, the energization pattern generation unit 16 generates an energization pattern for flowing current from the U-phase coil 212a to the V-phase coil 212b, and outputs the generated energization pattern to the PWM output unit 20. The PWM output unit 20 combines the duty value and the energization pattern, and outputs a PWM signal to the inverter circuit 22. Thereby, the inverter circuit 22 energizes the U-phase coil 212a and the V-phase coil 212b so that a current flows from the U-phase coil 212a to the V-phase coil 212b (S12).

  Next, the overcurrent determination unit 32 determines whether or not an overcurrent is flowing through the U-phase coil 212a and the V-phase coil 212b due to the energization of the coil 212 in S12 (S14). Even when the position where the rotor is difficult to move with respect to the coil 212 of the energized phase, if the duty value is too small, no overcurrent flows through the coil 212. That is, when no overcurrent flows through the coil 212, it can be determined that the rotor is rotating due to energization of the coil 212 or that the Duty value is too small.

  When it is determined in S14 that an overcurrent does not flow through the coil 212, the position detection unit 14 determines whether the rotational position of the rotor has been specified (S16). When the induced voltage is not specified with respect to the terminal voltage of the coil 212, the position detection unit 14 determines that the rotational position of the rotor is not specified, and does not change the value of the position detection signal.

  If the duty value is too small and the rotor is not rotating sufficiently, the position detection unit 14 does not specify the rotational position of the rotor in S16. If the position detection unit 14 determines that the rotation position of the rotor is not specified in S16, the Duty calculation unit 18 increases the Duty value (S18). In S18, the Duty calculating unit 18 increases the Duty value at a predetermined ratio set in advance.

  After the duty calculation unit 18 increases the duty value in S18, the PWM output unit 20 outputs a PWM signal based on the increased duty value. Thereby, the process returns to S12, and the inverter circuit 22 energizes the U-phase coil 212a and the V-phase coil 212b.

  According to the above, when no overcurrent flows through the coil 212, the driving device 100 repeatedly performs the processing of S12 to S18. According to this, in the duty control of the U-phase coil 212a and the V-phase coil 212b, the PWM output unit 20 increases the duty value from the initial value over time.

  When the overcurrent determining unit 32 determines that an overcurrent is flowing through the coil 212 in S14, the rotor may be located at a position where the rotor is difficult to move with respect to the U-phase coil 212a and the V-phase coil 212b that are the energized phases. There is. Therefore, the PWM output unit 20 stops the energization of the U-phase coil 212a and the V-phase coil 212b that have been energized in S12 (S20).

  In the drive device 100, the time from the start of the initial drive control to the stop of the energization of the coil 212 in S20 is set to within 4 ms. In other words, the initial value of the Duty value and the value for increasing the Duty value in S18 are set so that the time from the start of the initial drive control to the stop of energization of the coil 212 in S20 is within 4 ms. The initial value of the Duty value is, for example, 10%. The value by which the duty calculation unit 18 increases the duty value in S18 is, for example, 5%.

  After the PWM output unit 20 performs the processing of S20, the driving device 100 performs the same processing as that of the U-phase coil 212a and the V-phase coil 212b performed in S10 to S20, and the V-phase coil 212b and W in S22 to S32. This is performed for the phase coil 212c.

  After the PWM output unit 20 stops the energization in S20, the Duty calculation unit 18 initializes the Duty value (S22). At this time, the duty calculation unit 18 sets the duty value to the initial value used in S10. Thus, the duty value that has been increased by the duty calculation unit 18 in S18 returns to the initial value in S10.

  The energization pattern generation unit 16 generates an energization pattern in which current flows from the V-phase coil 212b to the W-phase coil 212c, and outputs the generated energization pattern to the PWM output unit 20. The PWM output unit 20 combines the energization pattern and the Duty value, and outputs a PWM signal to the inverter circuit 22. Thereby, the inverter circuit 22 energizes the V-phase coil 212b and the W-phase coil 212c so that a current flows from the V-phase coil 212b to the W-phase coil 212c (S24).

  Next, the overcurrent determination unit 32 determines whether an overcurrent is flowing through the coil 212 due to the energization of the coil 212 in S24 (S26). Then, if it is determined in S26 that no overcurrent is flowing through the coil 212, it is determined whether or not the position detection unit 14 has identified the rotational position of the rotor (S28).

  When the position detecting unit 14 does not specify the rotational position of the rotor in S28, the Duty calculating unit 18 increases the Duty value (S30). The rate at which the duty calculation unit 18 increases the Duty value in S30 is, for example, the same as the rate increased in S18.

  After the duty calculation unit 18 increases the duty value in S30, the PWM output unit 20 outputs a PWM signal based on the increased duty value. Thereby, the process returns to S24, and the inverter circuit 22 energizes the V-phase coil 212b and the W-phase coil 212c.

  According to the above, when no overcurrent flows through the coil 212, the driving device 100 repeatedly performs the processing of S24 to S30. According to this, the PWM output unit 20 increases the Duty value over time from the initial value in the Duty control on the coil 212 after the energization is switched.

  When the overcurrent determination unit 32 determines that an overcurrent is flowing through the coil 212 in S26, the rotor may be located at a position where the rotor is difficult to move with respect to the V-phase coil 212b and the W-phase coil 212c which are the energized phases. There is. Therefore, the PWM output unit 20 stops the energization of the V-phase coil 212b and the W-phase coil 212c that have been energized in S26 (S32).

  In the driving device 100, the time from the stop of energization of the coil 212 in S20 to the stop of energization of the coil 212 in S32 is set within 4 ms. In other words, the initial value of the Duty value and the value to increase the Duty value in S30 are set so that the time from the stop of the energization of the coil 212 in S20 to the stop of the energization of the coil 212 in S32 is within 4 ms. .

  After the PWM output unit 20 performs the process of S32, the driving device 100 performs the same process as the process on the V-phase coil 212b and the W-phase coil 212c performed in S22 to S32, and the W-phase coil 212c and U in S34 to S44. This is performed for the phase coil 212a.

  After the PWM output unit 20 stops energization in S32, the Duty calculation unit 18 initializes the Duty value (S34). At this time, the duty calculation unit 18 sets the duty value to the initial value used in S10, that is, the initial value used in S22. Thus, the duty value that has been increased by the duty calculating unit 18 in S30 returns to the initial value in S22.

  Then, the energization pattern generation unit 16 generates an energization pattern in which current flows from the W-phase coil 212c to the U-phase coil 212a, and outputs the generated energization pattern to the PWM output unit 20. The PWM output unit 20 combines the energization pattern and the Duty value, and outputs a PWM signal. Thereby, the inverter circuit 22 energizes the W-phase coil 212c and the U-phase coil 212a so that a current flows from the W-phase coil 212c to the U-phase coil 212a (S36).

  Next, the overcurrent determining unit 32 determines whether an overcurrent is flowing through the coil 212 due to the energization of the coil 212 in S36 (S38). Then, when it is determined in S38 that no overcurrent is flowing through the coil 212, it is determined whether or not the position detecting unit 14 has been able to identify the rotational position of the rotor (S40).

  If the position detecting unit 14 does not specify the rotational position of the rotor in S40, the Duty calculating unit 18 increases the Duty value (S42). The rate at which the duty calculation unit 18 increases the duty value in S42 is, for example, the same as the rate increased in S18 and S30.

  After the duty calculation unit 18 increases the duty value in S42, the PWM output unit 20 outputs a PWM signal based on the increased duty value. Thereby, the process returns to S36, and the inverter circuit 22 energizes the W-phase coil 212c and the U-phase coil 212a.

  According to the above, when the overcurrent does not flow through the coil 212, the driving device 100 repeatedly performs the processing of S36 to S42. According to this, similarly to the processing of S24 to S30, in the Duty control on the coil 212 after the energization is switched, the PWM output unit 20 increases the Duty value with time from the initial value.

  When the overcurrent determining unit 32 determines that an overcurrent is flowing through the coil 212 in S38, the brushless motor 200 is not located at a position where the rotor is not easily rotated with respect to the coil 212 of the energized phase. It can be regarded as being in a locked state. The locked state is a state of the brushless motor 200 in which the rotor is difficult to rotate for some reason.

  If the overcurrent determination unit 32 determines that an overcurrent is flowing through the coil 212 in S38, the PWM output unit 20 determines that the brushless motor 200 is in the locked state, and the W-phase coil that has been energized in S36. The energization of the 212c and the U-phase coil 212a is stopped (S44).

  In the driving device 100, the time from the stop of energization of the coil 212 in S32 to the stop of energization of the coil 212 in S44 is set to within 4 ms. In other words, the initial value of the Duty value and the value for increasing the Duty value in S42 are set so that the time from the stop of the energization of the coil 212 in S32 to the stop of the energization of the coil 212 in S44 is within 4 ms. . As described above, in the present embodiment, when the brushless motor 200 is in the locked state, the driving device 100 determines that the locked state is within 12 ms from the start of the initial drive control.

  After performing the processing of S44, the driving device 100 ends the initial driving control and does not perform the induction driving control. After S44, the drive device 100 outputs, for example, a signal indicating that the brushless motor 200 is in the locked state to the outside, or performs control on the assumption that the brushless motor 200 is in the locked state, for example, again after a predetermined time. Starting the initial drive control is performed.

  On the other hand, when the position detecting unit 14 specifies the rotational position of the rotor in S16, S28, and S40, the initial drive control ends and the induction drive control starts.

  Next, a processing procedure of the induced drive control will be described with reference to FIGS.

  When the induction drive control is started, the PWM output unit 20 determines whether the current time is the rotation check timing (S50). The rotation check timing is a period in which the driving device 100 stops the rotation of the rotor and specifies the rotational position of the rotor. By providing the rotation check timing, the drive device 100 can correct the rotation position and the rotation speed of the rotor when the rotation position of the rotor is erroneously specified. The rotation check timing is set based on, for example, the elapsed time after the start of the induced drive control and whether the rotation speed of the rotor is stable. Further, the drive device 100 may periodically provide a rotation check timing.

  If it is determined in S50 that the timing is not the rotation check timing, the PWM output unit 20 outputs a PWM signal corresponding to the rotational position of the rotor. Thereby, the inverter circuit 22 energizes the coil 212 (S52). The rotational position of the rotor used by the PWM output unit 20 in S52 is the rotational position of the rotor specified in the process immediately before S52 in the process of specifying the rotational position of the rotor in the initial drive control or the induced drive control. In S52, the PWM output unit 20 performs rectangular wave driving on the inverter circuit 22 by, for example, a 120-degree conduction method.

  Next, the position detection unit 14 determines whether or not an induced voltage is generated in the coil 212 that has been turned off in S52 based on the output signal of the comparator 12. Accordingly, the position detection unit 14 determines whether or not the rotation position of the rotor has been specified (S54). Then, the position detection unit 14 outputs a position detection signal corresponding to the determination result of S54 to the energization pattern generation unit 16 and the PWM output unit 20.

  If the position detection unit 14 does not specify the rotational position of the rotor in S54, the PWM output unit 20 returns to the process of S50. According to the above, when it is not the rotation check timing and the position detection unit 14 does not specify the rotation position of the rotor, the driving device 100 repeats the processing of S50 to S54.

  By the way, at the timing when the coil 212 is changed from the energized phase to the non-energized phase, that is, at the timing when the MOSFETs 26a and 26b are turned off from on, a return current flows through the diodes 28a and 28b. This return current causes spike noise in the terminal voltage of the corresponding coil 212. Therefore, the output signal of the comparator 12 changes at the timing when the spike noise occurs, in addition to the timing when the induced voltage occurs.

  On the other hand, as shown in FIGS. 4 to 6, the position detection unit 14 provides a monitoring period for the output signal of each comparator 12 so that the rotational position of the rotor is not erroneously specified by spike noise. A period other than the monitoring period in the period in which the coil 212 is de-energized is referred to as a mask period.

  The position detector 14 monitors the change of the output signal of the comparator 12 only during the monitoring period, and does not reflect the change of the output signal during the mask period on the position detection signal. The position detector 14 monitors, as monitoring periods, a monitoring period Tu for monitoring the output signal of the U-phase comparator 12a, a monitoring period Tv for monitoring the output signal of the V-phase comparator 12b, and an output signal of the W-phase comparator 12c. It has a monitoring period Tw.

  FIG. 4 illustrates an output signal of the W-phase comparator 12c indicating whether an induced voltage is generated in the W-phase coil 212c. The position detection unit 14 provides a mask period until a predetermined time elapses after the W-phase coil 212c is set to the non-energized phase. Then, the position detection unit 14 provides a monitoring period Tw after a predetermined time has elapsed from the timing when the W-phase coil 212c is set to the non-energized phase, and ends the monitoring period Tw when the W-phase coil 212c is energized. The position detection unit 14 provides a monitoring period Tu for the U-phase coil 212a and a monitoring period Tv for the V-phase coil 212b in the same manner as providing the monitoring period Tw for the W-phase coil 212c. Is provided.

  In the present embodiment, the position detection unit 14 specifies the induced voltage generated in the terminal voltage of the coil 212 by specifying the rising edge of the output signal of the comparator 12 during the monitoring period. More specifically, when the output signal of the comparator 12 is High during the monitoring period, the position detection unit 14 determines that the rising edge of the output signal of the comparator 12 has been specified. That is, when the output signal of the comparator 12 is High during the monitoring period, the position detection unit 14 determines that the induced voltage has been specified and determines that the rotational position of the rotor has been specified.

  When the position detecting unit 14 specifies the rotational position of the rotor in S54, the duty calculating unit 18 calculates the current value of the rotational speed of the rotor based on the position detection signal (S56). The rotational speed of the rotor is the difference between the rotational angle of the rotor determined to be detected by the position detector 14 in S54 immediately before S56 and the rotational position of the rotor detected immediately before S54. Divided by the time taken to rotate.

  Next, the duty calculation unit 18 calculates a duty value based on the rotation speed calculated in S56 (S58). More specifically, the duty calculation unit 18 calculates the duty value so that the current value of the rotation speed of the rotor becomes the target value. The duty calculation unit 18 outputs the calculated duty value to the PWM output unit 20.

  Next, the PWM output unit 20 determines whether the Duty value calculated in S58 is 0% (S60). For example, when stopping the rotation of the rotor, the Duty calculating unit 18 sets the Duty value to 0% in S58. When determining that the Duty value is 0% in S60, the PWM output unit 20 stops the energization of the coil 212 that has been energized in S52 (S62). After performing the process of S62, the PWM output unit 20 ends the induction drive control.

  If the PWM output unit 20 determines that the Duty value is not 0% in S60, the process returns to S50. According to the above, when it is not the rotation check timing and the duty value is not 0%, the driving device 100 repeats the processing of S50 to S60.

  As described above, the position detection unit 14 does not monitor the output signal of the comparator 12 during the mask period because the monitoring period is provided for the output signal of the comparator 12. Therefore, the output signal of the comparator 12 may not change as expected during the mask period. That is, the rotor may not rotate as expected during the mask period.

  In this case, for example, the position detection unit 14 should specify the rotation position of the rotor every one rotation, but may specify the rotation position every 1/2 rotation or every 1/3 rotation. That is, the position detecting unit 14 may erroneously identify the rotational position of the rotor due to the provision of the monitoring period. In this case, the duty calculation unit 18 erroneously calculates the current value of the rotation speed of the rotor as a speed twice or three times faster than the actual speed. That is, the current value of the rotation speed of the rotor is １ ／ or の of the speed assumed by the driving device 100.

  In this case, the calculation of the duty value in S58 and the energization of the coil 212 corresponding to the rotational position of the rotor in S52 are not performed normally. FIG. 5 shows a case where the rotational speed of the rotor is １ ／ of the speed assumed by the drive device 100 due to erroneous identification of the rotational position of the rotor.

  The drive device 100 provides the above-described rotation check timing as a countermeasure against erroneous identification of the rotational position of the rotor. When determining that the current time is the rotation check timing in S50, the PWM output unit 20 stops energizing all the coils 212 of the three phases in the stator 210 (S64).

  In FIG. 6, the rotation check timing comes after the energization of the U-phase coil 212a and the V-phase coil 212b, and the PWM output unit 20 stops energization of all the coils 212 in S64. Hereinafter, a period during which the energization of the coil 212 is stopped is referred to as an energization stop period. Immediately after the start of the power supply stop period, spike noise occurs in the terminal voltage. Therefore, the position detection unit 14 provides a mask period for the output signal of the comparator 12 until a predetermined period elapses from the start of the power supply stop period.

  After a lapse of a predetermined period from the start of the energization stop period, the position detection unit 14 specifies a rotation period of the rotor by providing a monitoring period in the output signal of the comparator 12 (S66). In S66, the position detector 14 monitors the output signals of the three comparators 12. That is, during the power supply stop period, the position detection unit 14 determines whether an induced voltage is generated with respect to the terminal voltages of all the coils 212 of the three phases.

  In S66, for example, when there is a change in the output signal of any one of the comparators 12, the position detection unit 14 determines that the rotational position of the rotor has been specified. When there is no change in the output signal of the comparator 12, the position detection unit 14 determines that the rotational position of the rotor is not specified, and returns to the determination of S66. That is, when there is no change in the output signal of the comparator 12, the position detection unit 14 repeatedly performs the determination in S66.

  In the example shown in FIG. 6, after a predetermined time has elapsed from the start of the power supply stop period, it is determined that the position detection unit 14 has specified the rotational position of the rotor in S66 based on the output signal of the V-phase comparator 12b. When detecting the rotation position of the rotor in S66, the position detection unit 14 changes the value of the position detection signal according to the detected rotation position of the rotor.

  The PWM output unit 20 continues to stop energizing all the coils 212 even if the rotational position of the rotor is specified by the position detection unit 14 in S66 (S68). That is, even if the rotational position of the rotor is specified in S66, the PWM output unit 20 does not perform energization according to the specified rotational position of the rotor.

  Next, the position detector 14 performs the process of S54, and determines whether or not the rotational position of the rotor has been specified. At the timing when the process of S54 is performed immediately after S68, the energization to all the three-phase coils 212 is stopped. In S54 immediately after S68, the position detector 14 determines the rotational position of the rotor when the output signal of any one of the comparators 12 changes, for example, when the output signal of the U-phase comparator 12a changes. Judge as specified.

  In S54 immediately after S68, similarly to the processing in S54 immediately after S52, the process proceeds to S56 when the rotational position of the rotor is specified, and proceeds to S50 when the rotational position of the rotor is not specified. Even if the rotational position of the rotor is not specified in S54 immediately after S68, the process of S66 is performed again within the period of the rotation check timing, and the rotational position of the rotor is specified in the power supply stop period. You.

  According to the above, the position detection unit 14 specifies the rotation position of the rotor a plurality of times in a state where the energization of all the three-phase coils 212 is stopped during the rotation check timing. In the power supply stop period, the power supply to all three phases of the coils 212 is continuously stopped, so that no spike noise occurs in the terminal voltage of the coils 212. Therefore, in the power supply stop period, the position detecting unit 14 does not provide a mask period after specifying the rotation position of the rotor and before specifying the rotation position. In other words, the position detection unit 14 provides one continuous monitoring period for the output signal of the comparator 12 when specifying the rotational position of the rotor a plurality of times. That is, the position detection unit 14 specifies the induced voltage for the plurality of coils 212 in the non-energized phase a plurality of times in one uninterrupted monitoring period of the energization stop period.

  In the example illustrated in FIG. 6, the position detection unit 14 determines that the rotational position of the rotor has been specified in S54 based on the output signal of the U-phase comparator 12a being changed from Low to High during the power supply stop period. Then, when specifying the second rotation position of the rotor during the power-supply stop period, the position detection unit 14 changes the position detection signal according to the specified rotation position of the rotor. Therefore, in S56, the duty calculation unit 18 calculates the current value of the rotation speed of the rotor based on the two rotation positions of the rotor specified during the power supply stop period. According to this, the duty calculation unit 18 can correct the current value of the rotation speed of the rotor to a correct value when the current value is incorrectly calculated.

  In this case, the duty calculation unit 18 can correct the duty value to a correct value when the duty value is incorrectly calculated in step S58, as in step S56. Then, the duty calculation unit 18 outputs the corrected duty value to the PWM output unit 20.

  When the position detector 14 specifies the second rotation position of the rotor in S54 during the power-supply suspension period, the power-supply pattern generator 16 generates a power-supply pattern. At this time, the energization pattern generation unit 16 generates an energization pattern based on the two rotational positions of the rotor specified during the energization stop period. Thereby, the energization pattern generation unit 16 can correct the energization pattern to a correct pattern when an incorrect energization pattern is generated.

  Next, when the Duty value is not 0% and the current time is not the rotation check timing, the PWM output unit 20 performs the processing of S52. At this time, the PWM output unit 20 combines the Duty value calculated during the power supply stop period with the power supply pattern generated during the power supply stop period, and performs power supply according to the rotational position of the rotor. Thereby, the PWM output unit 20 can energize the coil 212 using the correct energization pattern and the correct Duty value.

  After the rotation position of the rotor is specified in S66 at the rotation check timing, if the rotation position of the rotor is not specified in S54, the passage of time elapses, and the rotation check is performed without specifying the next rotation position. Timing may end. In this case, the rotational position of the rotor is specified only once during the power supply stop period. Further, during the period of the rotation check timing, the rotation position of the rotor is specified in S66 and the rotation position is not specified in S54 is repeated, so that the rotation position may be specified three or more times during the power supply stop period. .

  Next, effects of the above-described driving device 100 will be described.

  If the rotor does not rotate in accordance with the position of the energized phase relative to the coil 212 even though the coil 212 is energized, the impedance becomes small and an overcurrent flows through the coil 212. On the other hand, in the initial drive control of the present embodiment, when an overcurrent flows through the coil 212 due to energization, the energization pattern generation unit 16 does not rotate the rotor according to the relative position of the energization phase to the coil 212. As a result, the energization pattern of the coil 212 is switched.

  When the PWM output unit 20 energizes the coil 212 based on the switched energization pattern, the relative position of the rotor with respect to the coil 212 in the energized phase can be changed. Thus, it is possible to prevent the rotor from rotating in accordance with the position of the energized phase relative to the coil 212. According to the above, the driving device 100 can start the brushless motor 200 without performing the initial setting. Therefore, it is possible to suppress an increase in the start-up time of the brushless motor 200.

  By the way, when the rotor is not rotating or the rotation speed of the rotor is low, the impedance is small, and an overcurrent is easily generated in the coil 212. That is, at the start of the rotation of the rotor, an overcurrent is easily generated in the coil 212. On the other hand, when the duty calculation unit 18 reduces the duty value, the overcurrent does not easily flow through the coil 212, but the rotor does not easily rotate, and the position detection unit 14 does not easily specify the rotation position of the rotor.

  On the other hand, in the present embodiment, in the initial drive control, the Duty calculation unit 18 increases the Duty value with the lapse of time from the start of energization of the coil 212. In addition, when the energization of the coil 212 is switched due to the overcurrent, the Duty calculation unit 18 initializes the Duty value, and increases the Duty value with the lapse of time from when the energization is switched. According to this, at the time of starting the rotation of the rotor, the drive device 100 can reduce the Duty value and rotate the rotor while suppressing the overcurrent from flowing through the coil 212. In addition, when the rotation of the rotor is started and the overcurrent hardly flows through the coil 212, the driving device 100 can increase the Duty value and suppress the rotation position of the rotor from being specified.

  In addition, in the initial drive control, when the overcurrent flows through the coil 212 even after the energization pattern of the coil 212 is switched due to the overcurrent in the initial drive control, the drive device 100 may determine that the brushless motor 200 is in the locked state. judge. According to this, it is not necessary to provide the drive device 100 with a lock detection unit for determining whether the brushless motor 200 is in the locked state.

  In the present embodiment, the position detection unit 14 specifies the induced voltage for the plurality of coils 212 in the non-energized phase a plurality of times in one uninterrupted monitoring period of the energization stop period. According to this, even when the rotor is not rotating as expected during the mask period, the driving device 100 can correct the rotational position and the rotational speed of the rotor to correct values. Therefore, the PWM output unit 20 can control the energization of the coil 212 based on the corrected rotation position and rotation speed of the rotor after the elapse of the energization stop period.

(Other embodiments)
As described above, the preferred embodiments of the present invention have been described. However, the present invention is not limited to the above embodiments, and can be variously modified and implemented without departing from the gist of the present invention.

  In the above-described embodiment, an example has been described in which the drive device 100 increases the Duty value over time in the initial drive control, but the present invention is not limited to this. The drive device 100 may make the Duty value constant in the initial drive control.

  In the above-described embodiment, an example has been described in which the drive device 100 determines that the brushless motor 200 is in the locked state when it determines that an overcurrent is flowing through the coil 212 in S38. However, it is not limited to this. If the drive device 100 determines in S38 that an overcurrent is flowing through the coil 212, the drive device 100 may return to the process of S10.

  In the above embodiment, the inverter circuit 22 has been described as including the three element modules 24 having the two MOSFETs 26a and 26b and the two diodes 28a and 28b, but the invention is not limited thereto. Inverter circuit 22 may be any as long as it allows coil 212 to be energized in accordance with the PWM signal from PWM output unit 20.

  In the above embodiment, the example in which the stator 210 has the three coils 212 has been described, but the present invention is not limited to this. The number of coils 212 may be plural.

  10: neutral point voltage generator, 12: comparator, 12a: U-phase comparator, 12b: V-phase comparator, 12c: W-phase comparator, 14: position detector, 16: energization pattern generator, 18: Duty calculator, 20 PWM output unit, 22 inverter circuit, 24 element module, 24a U-phase element module, 24b V-phase element module, 24c W-phase element module, 26a MOSFET, 26b MOSFET, 28a diode, 28b ... Diode, 30 ... Shunt resistor, 32 ... Overcurrent judging unit, 100 ... Driver, 200 ... Brushless motor, 210 ... Stator, 212 ... Coil, 212a ... U-phase coil, 212b ... V-phase coil, 212c ... W-phase coil

Claims (6)

A driving device for driving a brushless motor (200) having a stator (210) having a plurality of coils (212) and a rotor rotatable relative to the stator,
A position detector (14) for detecting a rotational position of the rotor based on an induced voltage generated in the coil in a non-energized phase when the rotor is rotating, and outputting a position detection signal;
At the start of energization of the coil, the rotor is rotated by energizing the coil to perform initial drive control for causing the position detection unit to detect the rotational position, and based on the detected position detection signal, An energization control unit (16, 18, 20) for performing induction drive control for rotating the rotor according to the induced voltage by controlling the energization;
A current detector (30) for detecting a current flowing through the coil and outputting a current detection signal;
An overcurrent determination unit (32) that determines whether or not an overcurrent is flowing through the coil based on the current detection signal;
In the initial drive control, the energization control unit switches the energized phase of the coil when it is determined that an overcurrent is flowing through the coil due to energization ,
In the initial drive control, the energization control unit energizes the coil by Duty control, and increases the Duty value as time elapses from the start of energization . A driving device for driving a brushless motor (200) having a stator (210) having a plurality of coils (212) and a rotor rotatable relative to the stator,
A position detector (14) for detecting a rotational position of the rotor based on an induced voltage generated in the coil in a non-energized phase when the rotor is rotating, and outputting a position detection signal;
At the start of energization of the coil, the rotor is rotated by energizing the coil to perform initial drive control for causing the position detection unit to detect the rotational position, and based on the detected position detection signal, An energization control unit (16, 18, 20) for performing induction drive control for rotating the rotor according to the induced voltage by controlling the energization;
A current detector (30) for detecting a current flowing through the coil and outputting a current detection signal;
An overcurrent determination unit (32) that determines whether or not an overcurrent is flowing through the coil based on the current detection signal;
In the initial drive control, the energization control unit switches the energized phase of the coil when it is determined that an overcurrent is flowing through the coil due to energization ,
In the initial drive control, the energization control unit energizes the coil by Duty control, and when the energized phase of the coil is switched by an overcurrent, sets the Duty value to an initial value and sets a time from the time of switching the energized phase. A drive device that increases the Duty value over time . A driving device for driving a brushless motor (200) having a stator (210) having a plurality of coils (212) and a rotor rotatable relative to the stator,
A position detector (14) for detecting a rotational position of the rotor based on an induced voltage generated in the coil in a non-energized phase when the rotor is rotating, and outputting a position detection signal;
At the start of energization of the coil, the rotor is rotated by energizing the coil to perform initial drive control for causing the position detection unit to detect the rotational position, and based on the detected position detection signal, An energization control unit (16, 18, 20) for performing induction drive control for rotating the rotor according to the induced voltage by controlling the energization;
A current detector (30) for detecting a current flowing through the coil and outputting a current detection signal;
An overcurrent determination unit (32) that determines whether or not an overcurrent is flowing through the coil based on the current detection signal;
In the initial drive control, the energization control unit switches the energized phase of the coil when it is determined that an overcurrent is flowing through the coil due to energization ,
The drive device in which the brushless motor is in a locked state when it is determined in the initial drive control that the overcurrent is flowing through the coil even after switching the current-carrying phase of the coil due to the overcurrent. . In the initial drive control, the energization control unit sets the Duty value to an initial value when the energized phase of the coil is switched by an overcurrent when the energized state of the coil is switched by the Duty control, and sets the time from the time when the energized phase is switched. 4. The driving device according to claim 3 , wherein the duty value increases with time. The drive device according to any one of claims 2 to 4, wherein in the initial drive control, the energization control unit energizes the coil by duty control, and increases the Duty value as time elapses from the start of energization. The position detecting unit detects the rotational position by specifying the induced voltage only during a monitoring period (Tw, Tu, Tv) during which spike noise does not occur in a period in which the coil is in the non-energized phase. Monitoring the voltage of the coil,
In the induction drive control, the energization control unit provides an energization stop period for stopping energization for the plurality of coils,
The position detection unit outputs the position detection signal by performing the identification of the induced voltage a plurality of times for the plurality of coils in the non-energized phase in the one uninterrupted monitoring period of the energization stop period. And
The power supply controller after lapse of the energizing stop period, based on the position detection signal, the in response to the induced voltage specified multiple times with de-energization period of claims 1 to 5 for controlling the energization of said coil The driving device according to claim 1.

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