MOTOR DRIVE CONTROL DEVICE, MOTOR UNIT, AND MOTOR DRIVE CONTROL METHOD

Abstract

To improve drive efficiency of a motor by improving accuracy of phase adjustment without making a rotation speed of the motor unstable.SOLUTION: A motor drive control device 1 comprises: a target point determination section 12 for determining a target point P of zero cross of a coil current Iu of U phase based on a position detection signal Shu; a current zero cross point estimation section 14 for estimating a zero cross point Q of the coil current Iu of U phase by detecting a change in a current direction of the coil current Iu of U phase in predetermined timing for each period of a PWM signal; an adjustment instruction signal generation section 15 for generating, in accordance with a phase difference, at least one of a phase adjustment instruction signal Sp instructing a phase adjustment of the coil current Iu and a frequency adjustment instruction signal Sf instructing a frequency adjustment of the PWM signal in such a manner that a phase difference Δφ between the target point P and the zero cross point Q is settled within a predetermined range; and a drive control signal generation section 16 for generating a drive control signal Sd based on at least one of the phase adjustment instruction signal Sp and the frequency adjustment instruction signal Sf.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a motor drive control device, a motor unit, and a motor drive control method. [Background technology]

[0002] In general, when a motor having multi-phase coils is sinusoidally driven, it is known that the motor can be driven efficiently by matching the phase of the induced voltage in the coil with the phase of the coil current (phase current) for each phase of the motor.

[0003] However, due to changes in motor characteristics caused by the motor's rotation speed, motor load, and temperature, a shift may occur between the phase of the induced voltage and the phase of the coil current (phase current), which may result in a deterioration in the driving efficiency of the motor.

[0004] As a technique for solving such problems, a motor drive device that adjusts the phase of the coil drive voltage relative to the phase of the motor coil current is disclosed in Patent Document 1. The motor drive device disclosed in Patent Document 1 controls a positive side transistor and a negative side transistor connected in series between a DC power supply and ground to be complementarily turned on / off in response to an energization signal for controlling energization of a brushless motor, and supplies a pseudo-sine wave drive voltage to the coil of the brushless motor from an energization terminal between the positive side transistor and the negative side transistor to drive the motor.

[0005] In the motor driving device disclosed in Patent Document 1, a comparator compares a first voltage based on the voltage at one end of the negative-side transistor with a second voltage based on the voltage at the other end of the negative-side transistor to determine the polarity of the motor current flowing through the negative-side transistor based on a comparison result signal, and outputs a phase adjustment signal that adjusts the phase of the driving voltage based on a position detection signal, thereby adjusting the phase of the coil driving voltage relative to the phase of the motor coil current. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2015-62329 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the technology disclosed in Patent Document 1, if the motor current and the PWM signal, which is the drive voltage, become out of sync, a time gap occurs between the zero-cross point of the motor current and the timing of sampling, making it impossible to generate an accurate comparison result signal. As a result, phase adjustment is performed frequently, which may cause the rotation speed to become unstable.

[0008] The inventors of the present application therefore considered the need for a new motor drive control technique for improving the accuracy of phase adjustment and the drive efficiency of the motor without destabilizing the rotation speed of the motor.

[0009] The present invention has been made to solve the above-mentioned problems, and has an object to increase the accuracy of phase adjustment and improve the driving efficiency of the motor without making the rotation speed of the motor unstable. [Means for solving the problem]

[0010] A motor drive control device according to a representative embodiment of the present invention includes a control circuit that generates a drive control signal, which is a PWM signal for driving a motor having a coil of at least one phase, and a drive circuit that includes a high-side switch and a low-side switch connected in series to each other and provided corresponding to the coil of each phase of the motor, and alternately turns on and off the high-side switch and the low-side switch in response to the drive control signal to switch the direction of current flow through the coil of the corresponding phase. The control circuit includes a target point determination unit that is synchronized with an induced voltage of a coil of a predetermined phase of the motor and determines a target point of zero crossing of the coil current of the predetermined phase based on a position detection signal corresponding to the rotational position of a rotor of the motor, and a target point determination unit that determines a target point of zero crossing of the coil current of the predetermined phase based on a position detection signal corresponding to the rotational position of the rotor of the motor, and a predetermined a current zero cross point estimator that estimates a zero cross point of the coil current of the specified phase by detecting a change in the current direction of the coil current of the specified phase at a timing, an adjustment instruction signal generator that generates at least one of a phase adjustment instruction signal that instructs phase adjustment of the coil current and a frequency adjustment instruction signal that instructs frequency adjustment of the PWM signal in accordance with the phase difference so that the phase difference between the target point determined by the target point determination unit and the zero cross point estimated by the current zero cross point estimator is within a specified range, and a drive control signal generator that generates the drive control signal based on at least one of the phase adjustment instruction signal and the frequency adjustment instruction signal generated by the adjustment instruction signal generator. Effect of the Invention

[0011] According to one aspect of the present invention, it is possible to increase the accuracy of phase adjustment and improve the driving efficiency of the motor without making the rotation speed of the motor unstable. [Brief description of the drawings]

[0012] [Figure 1] 1 is a diagram showing a configuration of a motor unit equipped with a motor drive control device according to an embodiment of the present invention. [Diagram 2] 2 is a diagram showing the internal configuration of a PWM command unit 17. FIG. [Diagram 3]5 is a diagram for explaining a phase adjustment function of the motor drive control device according to the embodiment. FIG. [Figure 4A] 11 is a timing chart showing changes in the U-phase PWM signals Suu, Sul and the drive voltage Vu of the coil Lu when the U-phase coil current Iu switches from positive (+) polarity to negative (-) polarity. [Figure 4B] 11 is a timing chart showing changes in the U-phase PWM signals Suu, Sul and the drive voltage Vu of the coil Lu when the U-phase coil current Iu switches from negative (-) polarity to positive (+) polarity. [Figure 5A] 11 is a diagram for explaining a state in which the high-side switch QuH and the low-side switch QuL of the U-phase are turned off in a state in which a positive coil current Iu flows through the U-phase coil Lu. FIG. [Figure 5B] 13 is a diagram for explaining a state in which the high-side switch QuH and the low-side switch QuL of the U-phase are turned off in a state in which a negative coil current Iu flows through the U-phase coil Lu. FIG. [Figure 6] 11A and 11B are diagrams for explaining a determination as to whether or not a coil current adjustment is required. [Figure 7] 11 is a diagram showing the relationship between the phase difference Δφ between a target point P and a zero-cross point Q of a coil current and the zero-cross detection timing. [Figure 8] 4 is a flowchart showing a flow of a motor drive control process performed by the motor drive control device according to the embodiment. [Figure 9] 9 is a flowchart showing the process (step S4) of estimating the zero-crossing point of the coil current in FIG. 8. [Figure 10] 9 is a flowchart showing the flow of the motor coil current adjustment process (step S5) in FIG. 8. [Figure 11] 11 is a flowchart showing the process (step S60) of frequency adjustment 1 in FIG. [Figure 12] 11 is a flowchart showing the process (step S63) of frequency adjustment 2 in FIG. 10. [Figure 13]4 is a timing chart showing changes in the voltages of the signals and the coil current Iu when the phase of the coil current Iu of the motor is adjusted by the motor drive control device according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] 1. Overview of the embodiment First, a typical embodiment of the invention disclosed in this application will be outlined. In the following description, as an example, reference numerals in the drawings corresponding to components of the invention are given in parentheses.

[0014] [1] A motor drive control device (1) according to a representative embodiment of the present invention includes a control circuit (2) that generates drive control signals (Sd, Suu, Sul, Svu, Svl, Swu, Swl) which are PWM signals for driving a motor (5) having a coil of at least one phase, and a drive circuit (3) that includes high-side switches (QuH, QvH, QwH) and low-side switches (QuL, QvL, QwL) connected in series to each other and provided corresponding to the coils (Lu, Lv, Lw) of each phase of the motor, and that alternately turns on and off the high-side switches and the low-side switches in response to the drive control signal to switch the direction of current flow to the coil of the corresponding phase, and the control circuit is synchronized with an induced voltage of a coil of a predetermined phase (e.g., U phase) of the motor, and determines a zero-cross target point (P) of the coil current of the predetermined phase based on a position detection signal (Shu) corresponding to the rotational position of a rotor of the motor. The PWM signal generating device is characterized by comprising: a target point determination unit (12); a current zero-cross point estimation unit (14) that estimates a zero-cross point (Q(tq)) of a coil current of a specified phase by detecting a change in the current direction of the coil current of the specified phase at a specified timing for each cycle of the PWM signal; an adjustment instruction signal generation unit (15) that generates at least one of a phase adjustment instruction signal (Sp) that instructs phase adjustment of the coil current and a frequency adjustment instruction signal (Sf) that instructs frequency adjustment of the PWM signal in accordance with the phase difference (Δφ) so that the phase difference (Δφ) between the target point determined by the target point determination unit and the zero-cross point estimated by the current zero-cross point estimation unit is within a specified range; and a drive control signal generation unit (16) that generates the drive control signal based on at least one of the phase adjustment instruction signal (Sp) and the frequency adjustment instruction signal (Sf) generated by the adjustment instruction signal generation unit (15).

[0015] [2] In the motor drive control device described in [1] above, the current zero-cross point estimating unit may compare the drive voltage of a coil of the specified phase with at least one of an on period and an off period of a signal that turns on and off the high-side switch corresponding to the specified phase, and detect a change in the current direction of the coil current of the specified phase based on the comparison result.

[0016] [3] In the motor drive control device described in [1] or [2] above, the control circuit may synchronize the PWM signal with the position detection signal at a timing before estimating a zero-cross point of the coil current of the specified phase.

[0017] [4] In the motor drive control device described in [1] to [3] above, when the phase difference is outside a first range, the adjustment instruction signal generating unit may generate only the phase adjustment instruction signal until the phase difference falls within the first range, and when the phase difference falls within the first range, generate at least one of the frequency adjustment instruction signal and the phase adjustment instruction signal.

[0018] [5] In the motor drive control device described in [4] above, the adjustment instruction signal generating unit may prohibit generation of the phase adjustment instruction signal and generate only the frequency adjustment instruction signal when the phase difference is within a second range inside the first range.

[0019] [6] In the motor drive control device described in [4] or [5] above, the adjustment instruction signal generating unit may instruct, by the frequency adjustment instruction signal, to adjust the frequency of the PWM signal for each smallest unit of frequency, and generate the frequency adjustment instruction signal at predetermined time intervals.

[0020] [7] In the motor drive control device described in [6] above, the adjustment instruction signal generating unit may instruct, by the frequency adjustment instruction signal, to increase the frequency of the PWM signal until it reaches a maximum frequency within a predetermined frequency range, or to decrease the frequency of the PWM signal until it reaches a minimum frequency within the predetermined frequency range.

[0021] [8] In the motor drive control device described in [5] above, the adjustment instruction signal generating unit may terminate generation of the frequency adjustment instruction signal when the phase difference falls within a third range inside the second range.

[0022] [9] In the motor drive control device described in [1] to [8] above, the drive control signal generating unit may have a PWM command unit that generates an operation amount of the drive control signal, and a PWM signal generating unit that generates the drive control signal based on a previous operation amount, and the PWM command unit may have a rotational speed setting unit that determines a rotational speed setting value based on a rotational speed command value and a current rotational speed, a phase setting unit that determines a phase setting value based on the phase adjustment instruction signal, a frequency setting unit that determines a frequency setting value based on the frequency adjustment instruction signal, and an operation amount determination unit that determines the operation amount based on the determined rotational speed setting value, phase setting value, and frequency setting value.

[0023]

[10] A motor unit according to a representative embodiment of the present invention includes the motor drive control device described in [1] to [9] above, and the motor.

[0024]

[11] A motor drive control method according to a representative embodiment of the present invention is a motor control method using a motor drive control device including a control circuit that generates a drive control signal, which is a PWM signal for driving a motor having a coil of at least one phase, and a drive circuit including a high-side switch and a low-side switch connected in series to each other and provided corresponding to the coil of each phase of the motor, and which switches a current direction of the coil of the corresponding phase by alternately turning on / off the high-side switch and the low-side switch in response to the drive control signal, the method including: a first step in which the control circuit determines a target point of zero crossing of the coil current of the specified phase based on a position detection signal that is synchronized with an induced voltage of the coil of a specified phase of the motor and corresponds to a rotational position of a rotor of the motor; The method includes a second step in which the control circuit estimates a zero-crossing point of the coil current of the specified phase by detecting a change in the current direction of the coil current of the specified phase at a predetermined timing for each cycle of the PWM signal; a third step in which the control circuit generates at least one of a phase adjustment instruction signal that instructs phase adjustment of the coil current and a frequency adjustment instruction signal that instructs frequency adjustment of the PWM signal in accordance with the phase difference (Δφ) so that the phase difference between the target point determined in the first step and the zero-crossing point estimated in the second step is within a predetermined range; and a fourth step in which the control circuit generates the drive control signal based on at least one of the phase adjustment instruction signal and the frequency adjustment instruction signal generated in the third step.

[0025] 2. Specific examples of embodiments DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific examples of embodiments of the present invention will be described with reference to the drawings. In the following description, components common to the respective embodiments are designated by the same reference numerals, and repeated description will be omitted.

[0026] <Embodiment> FIG. 1 is a diagram showing the configuration of a motor unit equipped with a motor drive control device according to an embodiment of the present invention.

[0027] The motor unit 100 shown in FIG. 1 includes a motor 5, a position detector 6, and a motor drive control device 1.

[0028] The motor 5 is a motor having at least one coil, for example, a brushless DC motor having three-phase (U-phase, V-phase, and W-phase) coils (windings) Lu, Lv, and Lw.

[0029] The position detector 6 is a detector that detects the position according to the rotation of the rotor of the motor 5 and generates a position detection signal Shu. The position detector 6 is, for example, a Hall element. The Hall element detects the magnetic poles of the rotor and outputs a Hall signal whose voltage changes according to the rotation of the rotor. The Hall signal is, for example, a pulse signal, and is input to the motor drive control device 1 as the position detection signal Shu.

[0030] In the motor unit 100, one Hall element serving as a position detector 6 is disposed at a position corresponding to any one of the coils Lu, Lv, Lw of the U-phase, V-phase, and W-phase of the motor 5. Therefore, the Hall signal output from the position detector 6 becomes a signal synchronized with the induced voltage of any one of the coils Lu, Lv, Lw of the U-phase, V-phase, and W-phase of the motor 5.

[0031] In this embodiment, one Hall element serving as the position detector 6 is disposed at a position corresponding to, for example, the U-phase coil. As a result, the position detection signal (Hall signal) Shu is synchronized with the induced voltage of the U-phase coil Lu of the motor 5, and becomes a signal corresponding to the rotational position of the rotor of the motor 5.

[0032] Although details will be described later, in this embodiment, as a specific example, the position detector 6 is disposed at a position where it can detect the rising edge of the output position detection signal (Hall signal) Shu at a timing delayed by 30 electrical degrees from the zero cross point of the induced voltage of the U-phase coil Lu.

[0033] The motor drive control device 1 is a device that controls the driving of the motor 5. The motor drive control device 1 performs sine wave driving of the motor 5, for example, by a one-sensor driving method based on a position detection signal Shu from one position detector 6 (Hall element) provided at a position corresponding to the U-phase coil Lu.

[0034] Specifically, the motor drive control device 1 includes a control circuit 2, a drive circuit 3, and a phase voltage detection circuit 4. The motor drive control device 1 is supplied with a DC voltage Vdd from an external DC power supply (not shown). The DC voltage Vdd is supplied to a power supply line (not shown) in the motor drive control device 1 via, for example, a protection circuit or the like, and is input as a power supply voltage to the control circuit 2 and the drive circuit 3 via the power supply line.

[0035] Note that the DC voltage Vdd is not directly supplied to the control circuit 2, but for example, a voltage obtained by lowering the DC voltage Vdd using a regulator circuit may be supplied to the control circuit 2 as a power supply voltage.

[0036] The drive circuit 3 is a circuit that drives the motor 5 based on a drive control signal Sd output from a control circuit 2 described later. The drive control signal Sd is a signal for controlling the drive of the motor 5. For example, the drive control signal Sd is a PWM signal for sinusoidal driving of the motor 5.

[0037] The drive circuit 3 switches the connection destination of the coils of the motor 5 between the DC voltage Vdd and the ground potential GND based on the drive control signal Sd, thereby switching the direction of the motor current to rotate the motor 5. Specifically, the drive circuit 3 includes high-side switches QuH, QvH, QwH and low-side switches QuL, QvL, QwL that are provided corresponding to the coils Lu, Lv, Lw of each phase of the motor 5 and are connected in series with each other. The drive circuit 3 turns on and off the high-side switches QuH, QvH, QwH and the low-side switches QuL, QvL, QwL in response to the PWM signals Suu, Svu, Swu, Sul, Svl, Swl as the drive control signal Sd to switch the current flow direction of each coil Lu, Lv, Lw.

[0038] The high-side switches QuH, QvH, and QwH are, for example, P-channel type Metal-Oxide-Semiconductor Field Effect Transistors (MOSFETs), and the low-side switches QuL, QvL, and QwL are, for example, N-channel type MOSFETs.

[0039] The high-side switches QuH, QvH, QwH and the low-side switches QuL, QvL, QwL may be other types of power transistors, such as an IGBT (Insulated Gate Bipolar Transistor).

[0040] As shown in Figure 1, the U-phase high-side switch QuH and low-side switch QuL are connected in series between a DC voltage Vdd and a ground potential GND to form one switching leg (arm). The connection point between the high-side switch QuH and the low-side switch QuL is connected to one end of the coil Lu. The high-side switch QuH is switched on and off by a PWM signal Suu. The low-side switch QuL is switched on and off by a PWM signal Sul.

[0041] The V-phase high-side switch QvH and low-side switch QvL are connected in series between the DC voltage Vdd and the ground potential GND to form one switching leg. The connection point between the high-side switch QvH and the low-side switch QvL is connected to one end of the coil Lv. The high-side switch QvH is switched on and off by the PWM signal Svu. The low-side switch QvL is switched on and off by the PWM signal Svl.

[0042] The W-phase high-side switch QwH and low-side switch QwL are connected in series between the DC voltage Vdd and the ground potential GND to form one switching leg. The connection point between the high-side switch QwH and the low-side switch QwL is connected to one end of the coil Lw. The high-side switch QwH is switched on and off by the PWM signal Swu. The low-side switch QwL is switched on and off by the PWM signal Swl.

[0043] In addition, parasitic diodes are formed in each transistor serving as the high-side switches QuH, QvH, QwH and the low-side switches QuL, QvL, QwL, and these diodes function as freewheeling diodes that return the coil current to the DC voltage Vdd or the ground potential GND.

[0044] The drive circuit 3 may have a pre-drive circuit for driving the high-side switch and the low-side switch of each phase based on the drive control signal Sd. Also, as shown in Fig. 1, a sense resistor for detecting the current of the motor 5 may be connected to the ground potential GND side of the drive circuit 3.

[0045] The phase voltage detection circuit 4 is a circuit for detecting the drive voltage of a coil of a predetermined phase of the motor 5. In this embodiment, the phase voltage detection circuit 4 detects, for example, the drive voltage Vu of the U-phase coil Lu and inputs it to the control circuit 2. The phase voltage detection circuit 4 is, for example, a resistive voltage divider circuit connected between one end of the coil Lu to which the U-phase high-side switch QuH and low-side switch QuL are connected and the ground potential GND.

[0046] Note that, while FIG. 1 shows, as an example, a configuration in which the drive voltage Vu of the coil Lu is divided by a resistive voltage divider circuit serving as the phase voltage detection circuit 4 and input to the control circuit 2, the drive voltage Vu of the coil Lu may be input directly to the control circuit 2 without providing the phase voltage detection circuit 4.

[0047] The control circuit 2 is a circuit for comprehensively controlling the operation of the motor drive control device 1. In this embodiment, the control circuit 2 is a program processing device having a configuration in which a processor such as a CPU, various storage devices such as a RAM, a ROM, and a flash memory, and peripheral circuits such as a counter (timer), an A / D conversion circuit, a D / A conversion circuit, a clock generation circuit, and an input / output interface circuit are connected to each other via a bus or a dedicated line. For example, the control circuit 2 is a microcontroller (MCU: Micro Controller Unit).

[0048] The control circuit 2 and the drive circuit 3 may be configured to be packaged as a single semiconductor integrated circuit (IC: Integrated Circuit), or may be configured to be packaged as separate integrated circuits, mounted on a circuit board, and electrically connected to each other on the circuit board.

[0049] The control circuit 2 has a basic function of controlling the energization of the motor 5 by generating a drive control signal Sd and providing it to the drive circuit 3. Specifically, based on a drive command signal Sc input from the outside (e.g., a higher-level device) indicating a target value related to the drive of the motor 5 and a position detection signal Shu input from the position detector 6, the control circuit 2 generates a drive control signal Sd and provides it to the drive circuit 3 so that the motor 5 is in a drive state specified by the drive command signal Sc.

[0050] In addition to the above basic functions, the control circuit 2 has a function (hereinafter also referred to as a "coil current adjustment function") of adjusting the phase and period of the coil current of the motor 5 so that the phase of the induced voltage in a coil of a predetermined phase of the motor 5 and the phase of the coil current coincide with each other in order to improve the drive efficiency of the motor 5. Note that in this embodiment, "coinciding" includes that the error is within a predetermined allowable range, and is not limited to the coil current adjustment function completely matching the phase of the induced voltage in a coil of a predetermined phase of the motor 5 and the phase of the coil current.

[0051] As shown in FIG. 1, the control circuit 2 has, as functional units for realizing the above-mentioned functions, for example, a drive command analysis unit 11, a target point determination unit 12, a phase voltage input unit 13, a current zero-cross point estimation unit 14, an adjustment instruction signal generation unit 15, and a drive control signal generation unit 16.

[0052] Each of the above-mentioned functional units of the control circuit 2 is realized, for example, by program processing of an MCU serving as the control circuit 2. Specifically, a processor constituting the MCU serving as the control circuit 2 performs various calculations in accordance with a program stored in a memory to control various peripheral circuits constituting the MCU, thereby realizing each of the above-mentioned functional units.

[0053] The drive command analysis unit 11 receives, for example, a drive command signal Sc output from a higher-level device (not shown). The drive command signal Sc is a signal indicating a target value related to the drive of the motor 5, for example, a speed command signal indicating a target rotation speed of the motor 5.

[0054] The drive command analysis unit 11 analyzes the target rotation speed specified by the drive command signal Sc. For example, when the drive command signal Sc is a PWM signal having a duty ratio corresponding to the target rotation speed, the drive command analysis unit 11 analyzes the duty ratio of the drive command signal Sc and outputs information on the rotation speed corresponding to the duty ratio as the target rotation speed S1.

[0055] The drive control signal generator 16 calculates an operation amount S3 of the motor 5 so that the rotation speed of the motor 5 coincides with the target rotation speed S1, and generates a drive control signal Sd based on the calculated operation amount S3. Among the functions of the drive control signal generator 16, a function related to coil current adjustment will be described later.

[0056] The drive control signal generating unit 16 has, for example, a PWM command unit 17 and a PWM signal generating unit 18. The PWM command unit 17 calculates an operation amount S3 of the motor 5 based on a position detection signal Shu input from the position detector 6, a target rotation speed S1 input from the drive command analyzing unit 11, and a phase adjustment command signal Sp and a frequency adjustment command signal Sf input from an adjustment command signal generating unit 15 described later.

[0057] The manipulated variable S3 includes information specifying the drive amount of the motor 5 required to rotate the motor 5 at the target rotation speed S1. For example, when the motor 5 is PWM-driven as in this embodiment, the manipulated variable S3 includes a value specifying the period (PWM period) of the PWM signal serving as the drive control signal Sd, a value specifying the ON period of the PWM signal, and a value specifying the output timing of the PWM signal.

[0058] FIG. 2 is a diagram showing the internal configuration of the PWM command unit 17. 2, the PWM command unit 17 has a rotation speed setting unit 171, a phase setting unit 172, a frequency setting unit 173, and a manipulated variable determination unit 174. Of the PWM command unit 17, the phase setting unit 172, the frequency setting unit 173, and the manipulated variable determination unit 174 are functional units for realizing the coil current adjustment function of the motor 5 described above.

[0059] The rotation speed setting unit 171 determines a set value of the rotation speed from the position detection signal Shu input from the position detector 6 and the target rotation speed S1 output from the drive command analysis unit 11. For example, the rotation speed setting unit 171 calculates an actual rotation speed of the motor 5 based on the position detection signal Shu, and performs a PID (Proportional-Integral-Differential) control calculation so that the calculated actual rotation speed coincides with the target rotation speed S1 output from the drive command analysis unit 11, thereby determining the set value of the rotation speed.

[0060] The phase setting unit 172 determines a setting value of the phase based on a phase adjustment instruction signal Sp output from an adjustment instruction signal generating unit 15, which will be described later.

[0061] The frequency setting unit 173 determines the set value of the frequency based on a frequency adjustment instruction signal Sf output from an adjustment instruction signal generating unit 15, which will be described later.

[0062] The manipulated variable determination unit 174 calculates a value specifying the PWM period of the drive control signal Sd and a value specifying the on-period of the PWM signal based on the rotation speed setting value determined by the rotation speed setting unit 171, the phase setting value determined by the phase setting unit 172, and the frequency setting value determined by the frequency setting unit 173, and determines (generates) the manipulated variable S3 (including the PWM period, on-period, and output timing) and outputs it to the PWM signal generation unit 18.

[0063] It should be noted that the motor drive control device 1 in FIG. 1 has a feedback control function, but if it does not have the feedback control function, the rotational speed setting unit 171 may determine the setting value of the rotational speed from the target rotational speed S1 output from the drive command analysis unit 11.

[0064] The PWM signal generating unit 18 generates the drive control signal Sd based on the operation amount S3 input from the PWM command unit 17. Specifically, the PWM signal generating unit 18 generates six types of PWM signals Suu, Sul, Svu, Svl, Swu, and Swl each having a PWM cycle and an on-period specified by the operation amount S3, and outputs them as the drive control signal Sd.

[0065] In this embodiment, a dead time period Td is provided so that the high-side switch and the low-side switch constituting each switch leg of the U phase, the V phase, and the W phase are not turned on at the same time. That is, the PWM signal generating unit 18 generates the drive control signal Sd (the above six types of PWM signals) so that when the on / off state of the high-side switch and the low-side switch constituting each switch leg of the U phase, the V phase, and the W phase is switched, a dead time period Td in which the high-side switch and the low-side switch are turned off at the same time is formed. Details of the dead time period Td will be described later.

[0066] The target point determination unit 12, the phase voltage input unit 13, the current zero cross point estimation unit 14, and the adjustment instruction signal generation unit 15 are functional units for realizing the above-mentioned coil current adjustment function of the motor 5. Before describing each functional unit in detail, an overview of the motor current adjustment function according to this embodiment will be described.

[0067] FIG. 3 is a diagram for explaining phase adjustment, which is one of the motor current adjustment functions performed by the motor drive control device 1 according to the embodiment.

[0068] The upper part of Figure 3 shows a waveform 200 of the position detection signal (Hall signal) Shu output from the position detector 6, the middle part shows a waveform 201 of the drive voltage Vu of the U-phase coil Lu and a waveform 202 of the induced voltage in the U-phase coil Lu, and the lower part shows a waveform 203 of the coil current Iu of the U-phase coil Lu.

[0069] As described above, generally, a shift may occur between the phase of the induced voltage of the motor and the phase of the coil current due to changes in motor characteristics caused by the motor rotation speed, motor load, and temperature, etc. For example, Fig. 3 shows a case where the phase of the U-phase coil current Iu lags behind the phase of the induced voltage of the U-phase coil Lu.

[0070] 3, when a phase shift occurs between the coil current Iu and the induced voltage, the driving efficiency of the motor 5 decreases. Therefore, the motor drive control device 1 according to this embodiment detects the shift (phase difference) between the coil current Iu and the induced voltage, and adjusts the motor current supply timing (output timing of the PWM signal) so as to reduce the phase difference.

[0071] Specifically, first, the motor drive control device 1 detects the zero-cross point of the induced voltage by utilizing the fact that the position detection signal (Hall signal) Shu output from the position detector 6 (Hall element) provided corresponding to a specified phase is synchronized with the induced voltage of the coil of the specified phase, and sets this as the target point P of the zero-cross of the coil current Iu.

[0072] In this embodiment, for example, as shown in Fig. 3, the position detector 6 is disposed in advance at a position where the rising edge of the position detection signal Shu from the position detector 6 can be detected at a timing delayed by 30 electrical degrees from the zero-cross point of the induced voltage in the U-phase coil Lu. This allows the motor drive control device 1 to detect (estimate) the zero-cross point of the induced voltage in the coil Lu by detecting the edge of the position detection signal Shu.

[0073] The location of the position detector 6 need only be a location where the phase difference between the timing at which the rising edge of the position detection signal Shu is detected and the zero cross point of the induced voltage of a coil of a specified phase is known, and is not limited to the example described above.

[0074] The motor drive control device 1 detects the rising edge or the falling edge of the position detection signal Shu, and estimates the zero-cross point of the induced voltage from at least one of the detected edges. The motor drive control device 1 determines the estimated zero-cross point of the induced voltage as the target point P of the zero-cross of the coil current Iu.

[0075] Next, the motor drive control device 1 estimates the zero cross point of the coil current of a predetermined phase (U phase in this embodiment) by detecting a change in the current direction of the coil current of the predetermined phase at a predetermined timing for each cycle of the PWM signal. Specifically, the motor drive control device 1 compares the drive voltage (phase voltage) of the coil of the predetermined phase (U phase in this embodiment) with at least one of the on period and the off period of a signal for turning on and off a high-side switch corresponding to the predetermined phase, and estimates the zero cross point Q of the coil current of the predetermined phase of the motor based on the comparison result. Note that the method of estimating the zero cross point Q of the coil current will be described in detail later. It is preferable to synchronize the PWM signal with the position detection signal at a timing before estimating the zero cross point of the coil current of the predetermined phase.

[0076] Then, the motor drive control device 1 adjusts the phase of the coil current Iu so that the zero-cross point Q of the estimated coil current Iu coincides with the zero-cross target point P of the coil current Iu (the zero-cross point of the induced voltage). For example, as shown in Fig. 3, the phase of the coil current Iu is adjusted by adjusting the timing of application of the drive voltage Vu to the U-phase coil Lu (performing advance angle adjustment or delay angle adjustment) so that the zero-cross point Q of the U-phase coil current Iu coincides with the target point P. This enables the motor drive control device 1 to improve the drive efficiency of the motor 5.

[0077] At this time, since the zero-cross point Q of the coil current of a predetermined phase of the motor is estimated at a predetermined timing for each cycle of the motor drive signal, there is a possibility that the estimated zero-cross point Q may deviate from the actual zero-cross point in a time range corresponding to one cycle of the motor drive signal. The frequency adjustment of the coil current adjustment function of the motor drive control device 1 according to the embodiment can reduce the possibility of a deviation between the estimated zero-cross point Q of the coil current of a predetermined phase of the motor and the actual zero-cross point.

[0078] The frequency adjustment of the coil current adjustment function is to appropriately adjust the period of the motor drive signal by adjusting the frequency of the PWM signal. By appropriately adjusting the period of the motor drive signal, the time range in which the deviation exists can be made appropriate, thereby improving the accuracy of the estimation. The frequency adjustment may be performed according to the phase difference between the estimated zero cross point Q of the coil current Iu and the target point P of the zero cross of the coil current Iu.

[0079] Hereinafter, each of the functional units for realizing the above-mentioned coil current adjustment function will be described in detail.

[0080] The target point determination unit 12 determines a zero-cross target point of the coil current of a predetermined phase based on a position detection signal Shu that is synchronized with the induced voltage of the coil of a predetermined phase of the motor 5 and corresponds to the rotational position of the rotor of the motor 5.

[0081] In this embodiment, the target point determination unit 12 detects a rising edge or a falling edge of the position detection signal Shu synchronized with the induced voltage of the U-phase coil Lu, and determines the zero cross point of the induced voltage of the U-phase coil Lu, i.e., the target point P of the zero cross of the U-phase coil current Iu, based on the detected edge. For example, in FIG. 3, when the target point determination unit 12 detects the rising edge of the position detection signal Shu at time t1, the target point determination unit 12 determines time (timing) t0 that is 30 electrical degrees ahead of time t1 as the target point P. Note that the target point P is also determined in a similar manner when detecting the falling edge of the position detection signal Shu.

[0082] The phase voltage input unit 13 acquires the value of a voltage of a predetermined phase of the motor 5. For example, the phase voltage input unit 13 acquires a drive voltage Vu of a U-phase coil Lu detected by the phase voltage detection circuit 4, converts it into a digital value, and provides it to the current zero-cross point estimation unit 14.

[0083] The current zero cross point estimation unit 14 estimates the zero cross point of the coil current of a predetermined phase by detecting a change in the current direction of the coil current of a predetermined phase at a predetermined timing for each cycle of the PWM signal. Specifically, the current zero cross point estimation unit 14 is a functional unit that compares, for each cycle of the drive control signal Sd, which is a PWM signal, the drive voltage (phase voltage) of the coil of the predetermined phase with at least one of the on period and the off period of a signal that turns on and off a high-side switch corresponding to the predetermined phase, and estimates the zero cross point of the coil current of the predetermined phase based on the comparison result. Hereinafter, a method of estimating the zero cross point of the coil current by the current zero cross point estimation unit 14 will be described in detail with reference to the drawings.

[0084] FIG. 4A is a timing chart showing changes in the U-phase PWM signals Suu, Sul and the drive voltage Vu of the coil Lu when the U-phase coil current Iu switches from positive (+) polarity to negative (-) polarity. FIG. 4B is a timing chart showing changes in the U-phase PWM signals Suu, Sul and the drive voltage Vu of the coil Lu when the U-phase coil current Iu switches from negative (-) polarity to positive (+) polarity.

[0085] 4A and 4B, from top to bottom, the waveforms of the U-phase coil current Iu, the PWM signal Suu for driving the U-phase high-side switch QuH, the PWM signal Sul for driving the U-phase low-side switch QuL, and the drive voltage Vu of the U-phase coil Lu are shown in this order. Note that in Fig. 4A and 4B, the horizontal axis represents time, and the vertical axis represents current or voltage, respectively.

[0086] FIG. 5A is a diagram for explaining a state when the U-phase high-side switch QuH and low-side switch QuL are turned off in a state in which a positive (+) polarity coil current flows through the U-phase coil Lu. FIG. 5B is a diagram for explaining a state when the U-phase high-side switch QuH and low-side switch QuL are turned off in a state in which a negative (-) polarity coil current flows through the U-phase coil Lu.

[0087] 4A, when the PWM signal Suu is at a high level and the PWM signal Sul is at a low level, the U-phase high-side switch QuH is turned on and the U-phase low-side switch QuL is turned off. At this time, a current flows from the DC voltage Vdd through the U-phase high-side switch QuH to the U-phase coil Lu, so that the U-phase coil current Iu has a positive (+) polarity.

[0088] In this state, that is, when a positive (+) coil current Iu flows through the U-phase coil Lu, when both the U-phase high-side switch QuH and low-side switch QuL are turned off, the coil Lu tries to continue to pass current. Therefore, as shown in Fig. 5A, the positive coil current Iu flows from the ground potential GND through the parasitic diode of the low-side switch QuL. As a result, the drive voltage Vu of the coil Lu drops to near the ground potential GND.

[0089] Therefore, as shown in FIG. 4A, when the U-phase coil current Iu is positive (+) polarity, during the dead time period Td when the U-phase high-side switch QuH and low-side switch QuL are both off, the U-phase drive voltage Vu is at a low level.

[0090] As a result, as shown in FIG. 4A, during the period when the U-phase coil current Iu is positive (+), in one cycle of the PWM signal Suu, a first period Tv during which the drive voltage Vu of the U-phase coil Lu is at a high level coincides with a second period Th during which the PWM signal Suu that switches the U-phase high-side switch QuH on and off is at a high level.

[0091] 4B, when the PWM signal Suu is at a low level and the PWM signal Sul is at a high level, the U-phase high-side switch QuH is turned off and the U-phase low-side switch QuL is turned on. At this time, a current flows from the U-phase coil Lu to the ground potential GND via the U-phase low-side switch QuL, so the U-phase coil current Iu has a negative (-) polarity.

[0092] In this state, that is, when a negative (-) coil current Iu flows through the U-phase coil Lu, when the U-phase high-side switch QuH and low-side switch QuL are both turned off, the coil Lu tries to continue to pass a current. Therefore, as shown in FIG. 5B, a negative coil current Iu flows from the U-phase coil Lu to the DC voltage Vdd side via the parasitic diode of the high-side switch QuH. As a result, the drive voltage Vu of the coil Lu rises to near the DC voltage Vdd.

[0093] Therefore, as shown in FIG. 4B, when the U-phase coil current Iu has negative (-) polarity, during the dead time period Td when the U-phase high-side switch QuH and low-side switch QuL are both off, the U-phase drive voltage Vu is at a high level.

[0094] As a result, as shown in FIG. 4B, during the period when the U-phase coil current Iu has negative (-) polarity, in one cycle of the PWM signal Suu, the second period Th during which the PWM signal Suu that switches the U-phase high-side switch QuH on and off is at a high level is longer than the first period Tv during which the drive voltage Vu of the U-phase coil Lu is at a high level, and the first period Tv and the second period Th do not match.

[0095] As described above, when a motor is PWM driven, in one period of the PWM signal Suu, the first period Tv and the second period Th coincide during the period when the coil current of a specified phase is positive, and the first period Tv and the second period Th do not coincide during the period when the coil current is negative.

[0096] Therefore, as shown in Figures 4A and 4B, by detecting the timing of the transition from a state in which the first period Tv and the second period Th coincide to a state in which the first period Tv and the second period Th do not coincide, and the timing of the transition from a state in which the first period Tv and the second period Th do not coincide to a state in which the first period Tv and the second period Th coincide, it is possible to estimate the zero-crossing point of the coil current of a specified phase.

[0097] Therefore, the current zero-cross point estimation unit 14 monitors the drive voltage Vu of the U-phase coil Lu acquired by the phase voltage input unit 13 and the PWM signal Suu of the U-phase high-side switch QuH, and for each period of the PWM signal Suu, compares a first period Tv in which the drive voltage Vu of the U-phase coil Lu is at a high level with a second period Th in which the PWM signal Suu of the U-phase high-side switch QuH is at a high level, and determines whether the first period Tv and the second period Th match.

[0098] As described above, the switching of the drive voltage Vu to a high level or a low level and the switching of the PWM signal Suu to a high level or a low level correspond to the switching on / off of the U-phase high-side switch QuH. Therefore, in the following description, the first period Tv in which the drive voltage Vu is at a high level may be referred to as the "on period Tv," and the second period Th in which the PWM signal Suu is at a high level may be referred to as the "on period Th."

[0099] Whether or not the on-period (first period) Tv and the on-period (second period) Th match can be determined as follows.

[0100] For example, the current zero-cross point estimation unit 14 calculates the difference |Th-Tv| between the on-period Tv during which the drive voltage Vu of the U-phase coil Lu is at a high level and the on-period Th during which the PWM signal Suu of the U-phase high-side switch QuH is at a high level, and determines whether the difference |Th-Tv| is greater than or equal to a threshold value Tth.

[0101] When the difference |Th-Tv| is equal to or greater than the threshold value Tth, the current zero crossing point estimation unit 14 determines that the on-period Tv and the on-period Th do not match (are mismatched), and determines that the U-phase coil current Iu is negative. On the other hand, when the difference |Th-Tv| is less than the threshold value Tth, the current zero crossing point estimation unit 14 determines that the on-period Tv and the on-period Th match, and determines that the U-phase coil current Iu is positive.

[0102] Here, the threshold value Tth for determining whether the on-period Tv and the on-period Th match or not may be set based on the dead time period Td of the drive control signal Sd, which is a PWM signal. For example, Tth=Td may be set.

[0103] The current zero cross point estimation unit 14 detects (hereinafter also referred to as "zero cross detection") at least one of the timing when the on-period Tv and the on-period Th switch from a state in which they coincide to a state in which they do not coincide, and the timing when the on-period Tv and the on-period Th switch from a state in which they do not coincide to a state in which they coincide, and estimates the detected timing as the zero cross point Q of the U-phase coil current Iu.

[0104] That is, the current zero cross point estimation unit 14 determines the timing when the on-period (first period Tv) of the drive voltage Vu of the U-phase coil Lu and the on-period (second period Th) of the PWM signal of the U-phase high-side switch QuH switch from a matching state to a mismatching state as the zero cross point Q at which the polarity of the coil current Iu switches from positive to negative. The current zero cross point estimation unit 14 also determines the timing when the on-period Tv and the on-period Th switch from a mismatching state to a matching state as the zero cross point Q at which the polarity of the coil current Iu switches from negative to positive.

[0105] The current zero cross point estimator 14 executes zero cross detection at each zero cross detection interval, which is an interval that coincides with one period of the PWM signal. That is, the timing of zero cross detection in the current zero cross point estimator 14 is synchronized with the PWM signal. Therefore, the timing of zero cross detection can be adjusted by adjusting the output timing and period of the PWM signal. In this embodiment, the timing of zero cross detection in the current zero cross point estimator 14 is adjusted to suppress the deviation between the estimated zero cross point Q of the coil current of a specified phase of the motor and the actual zero cross point. The adjustment of the timing of zero cross detection will be described later.

[0106] For example, the current zero-cross point estimation unit 14 outputs to the adjustment instruction signal generation unit 15 a zero-cross point detection signal Sct that is at a high level when the on-period Tv and the on-period Th coincide (the coil current Iu is positive polarity) and is at a low level when the on-period Tv and the on-period Th do not coincide (the coil current Iu is negative polarity).

[0107] As a result, the adjustment instruction signal generating unit 15 can detect the edge (rising edge or falling edge) of the zero-crossing point detection signal Sct to know the zero-crossing point Q of the coil current Iu. For example, the first zero-cross detection timing after the zero-crossing point detection signal Sct falls and switches from high level to low level is the zero-crossing point Q at which the coil current Iu switches from positive to negative polarity, and the first zero-cross detection timing after the zero-crossing point detection signal Sct rises and switches from low level to high level is the zero-crossing point Q at which the coil current Iu switches from negative to positive polarity.

[0108] In the present embodiment, as described above, the current zero cross point estimation unit 14 compares the on-period (first period) Tv in which the drive voltage Vu of the U-phase coil Lu is at a high level with the on-period (second period) Th in which the PWM signal Suu of the U-phase high-side switch QuH is at a high level to determine the zero cross point Q of the coil current Iu, but is not limited to this. For example, the current zero cross point estimation unit 14 may compare, for each cycle of the PWM signal Suu, the off-period in which the drive voltage Vu of the U-phase coil Lu is at a low level with the off-period in which the PWM signal Suu of the U-phase high-side switch QuH is at a low level, and determine whether the two off-periods match each other to determine the zero cross point Q of the coil current Iu.

[0109] The adjustment instruction signal generating unit 15 generates at least one of a phase adjustment instruction signal that instructs phase adjustment of the coil current and a frequency adjustment instruction signal that instructs frequency adjustment of the PWM signal in accordance with the phase difference Δφ so that the phase difference Δφ between the target point P determined by the target point determining unit 12 and the zero cross point Q estimated by the current zero cross point estimating unit 14 falls within a predetermined range.

[0110] The adjustment instruction signal generating unit 15 first determines whether or not a coil current adjustment is necessary based on the phase difference Δφ between the zero crossing target point P of the coil current Iu determined by the target point determining unit 12 and the zero crossing point Q of the coil current Iu estimated by the current zero crossing point estimating unit 14.

[0111] For example, as shown in FIG. 3, the adjustment instruction signal generating unit 15 calculates a phase difference Δφ (=phase at time tp−phase at time tq) by subtracting the phase (time tq) of the zero cross point Q of the coil current Iu estimated by the current zero cross point estimating unit 14 from the phase (time tp) of the target point P (zero cross point of the induced voltage of the U-phase coil Lu) determined by the target point determining unit 12.

[0112] The adjustment instruction signal generating unit 15 judges whether the calculated phase difference Δφ is within a predetermined range, and determines whether the coil current adjustment is necessary depending on the judgment result. If it is determined that the coil current adjustment is necessary, it determines whether the coil current adjustment is to be performed by one of the following methods: performing only phase adjustment, performing only frequency adjustment, or performing both phase adjustment and frequency adjustment. Note that the phase adjustment may be "0 (zero)" (no phase adjustment is substantially performed). By switching the coil current adjustment method depending on the value of the calculated phase difference Δφ, it is possible to match the zero cross point Q of the coil current with the target point P while appropriately adjusting the timing of zero cross detection in the current zero cross point estimating unit 14.

[0113] FIG. 6 is a diagram for explaining a determination as to whether or not the coil current adjustment is required.

[0114] In FIG. 6, T1, T2, T3, T4, T1A, and T2A indicate phase positions that define a predetermined range. T3 and T2A are phase positions that coincide with the target point P determined by the target point determination unit 12, and the phase position that is shifted from this phase position to the advance side by only 0.5 periods of the PWM signal is T1A, the phase position that is shifted from the target point P to the advance side by only one period of the PWM signal is T2, and the phase position that is shifted from the target point P to the advance side by only 1.25 periods of the PWM signal is T1. Similarly, the phase position that is shifted from the target point P to the retard side by only 0.5 periods of the PWM signal is T4. The phase positions between T1 and T4 are defined as the first range E1, the phase positions between T2 and T3 (T2A) are defined as the second range E2, and the phase positions between T1A and T2A are defined as the third range E3. That is, the second range E2 exists inside the first range E1, and the third range E3 exists inside the second range E2, so that three ranges can be defined.

[0115] FIG. 7 is a diagram showing the relationship between the phase difference Δφ between the target point P and the zero-cross point Q of the coil current and the zero-cross detection timing.

[0116] FIG. 7 shows that when an actual zero-cross point exists between the target point P and a position one period of the PWM signal (corresponding to the zero-cross detection interval), the zero-cross point Q of the coil current is detected at a position according to the timing of the zero-cross detection.

[0117] 7, when the actual zero-cross point of the coil current exists between the target point P and a position advanced by one period of the PWM signal, the phase difference Δφ is equal to or less than one period of the PWM signal in the advance angle direction, and the detected zero-cross point Q of the coil current is shifted to a position according to the timing of the zero-cross detection. Therefore, when the phase difference Δφ is equal to or less than one period of the PWM signal in the advance angle direction, no phase adjustment is performed as the coil current adjustment, and the zero-cross detection interval is adjusted by adjusting the frequency to bring the position where the actual zero-cross point exists closer to the target point P. In this embodiment, when the zero-cross point Q exists between the target point P and a position advanced by 0.5 periods of the PWM signal, the target point P and the zero-cross point Q of the coil current coincide with each other, and no coil current adjustment is performed.

[0118] Furthermore, if the zero-cross point Q exists outside a position advanced by one PWM signal period from the target point P or a position delayed from the target point P (the phase difference Δφ is greater than one PWM signal period in the advance angle direction or is delayed), both phase adjustment and frequency adjustment are performed as the coil current adjustment. However, if the zero-cross point Q exists outside a position advanced by 1.25 PWM signal periods from the target point P or a position delayed by 0.5 PWM signal periods from the target point P (the phase difference Δφ is greater than 1.25 PWM signal periods in the advance angle direction or is delayed by 0.5 PWM signal periods in the delay angle direction), only phase adjustment is performed as the coil current adjustment.

[0119] Specifically, the adjustment instruction signal generating unit 15 determines the adjustment method depending on the position of the calculated phase difference Δφ relative to a predetermined range (E1, E2, where E1>E2). That is, when the adjustment instruction signal generating unit 15 determines that the calculated phase difference Δφ is within the second range E2 (the position where the zero cross point Q exists is between phase positions T2 and T3), it determines to perform only the frequency adjustment. On the other hand, when the adjustment instruction signal generating unit 15 determines that the calculated phase difference Δφ is outside the first range E1 (the position where the zero cross point Q exists is outside phase position T1 or outside T4), it determines to perform only the phase adjustment. Furthermore, when the adjustment instruction signal generating unit 15 determines that the calculated phase difference Δφ is not within the second range E2 (the position where zero cross point Q exists is between phase positions T2 and T3) and is within the first range E1 (the position where zero cross point Q exists is inside phase position T1 or T4) (between T1 and T2, between T3 and T4), it decides to perform at least one of phase adjustment and frequency adjustment. Note that when the adjustment instruction signal generating unit 15 determines that the calculated phase difference Δφ is within the third range E3 (E2>E3) (the position where zero cross point Q exists is between phase positions T1A and T2A (T3)), it does not perform either phase adjustment or frequency adjustment.

[0120] In frequency adjustment, the adjustment instruction signal generating unit 15 outputs a frequency adjustment instruction signal Sf to the drive control signal generating unit 16, which instructs the drive control signal Sd, which is a PWM signal, to be increased (up) by a predetermined minimum unit within a set range, and then, if necessary, to be decreased (down) by a predetermined minimum unit within the set range.

[0121] When the adjustment instruction signal generator 15 increases or decreases the frequency by a predetermined minimum unit, it does not increase or decrease the frequency continuously, but increases or decreases the frequency by the minimum unit every time a predetermined time interval elapses. By not increasing or decreasing the frequency abruptly, the rotation speed does not change abruptly, which prevents the motor current from becoming unstable.

[0122] In the phase adjustment, the adjustment instruction signal generation unit 15 instructs the drive control signal generation unit 16 to shift the output timing of the drive control signal Sd by a time corresponding to the phase difference Δφ (=phase at time tp−phase at time tq).

[0123] Specifically, when the phase difference Δφ is a positive (+) value, for example, when the phase difference Δφ is equal to or greater than a threshold value +φth, the adjustment instruction signal generation unit 15 determines that the phase of the coil current Iu leads the phase of the induced voltage of the U-phase coil Lu, and instructs the drive control signal generation unit 16 to perform a delay adjustment to delay the phase of the coil current Iu. For example, the adjustment instruction signal generation unit 15 outputs a phase adjustment instruction signal Sp that instructs the execution of a delay adjustment to delay the coil current Iu by only the phase difference Δφ.

[0124] When the phase difference Δφ is a negative (-) value, for example, when the phase difference Δφ is equal to or smaller than a threshold value -φth, the adjustment instruction signal generating unit 15 determines that the phase of the coil current Iu lags behind the phase of the induced voltage of the U-phase coil Lu, and instructs the drive control signal generating unit 16 to execute an advance adjustment to advance the phase of the coil current Iu. For example, the adjustment instruction signal generating unit 15 outputs a phase adjustment instruction signal Sp to the drive control signal generating unit 16 to instruct the execution of an advance adjustment to advance the coil current Iu by only the phase difference Δφ.

[0125] Furthermore, for example, when the phase difference Δφ is greater than a threshold value -φth and less than a threshold value +φth (-φth<Δφ<+φth), the adjustment instruction signal generating unit 15 determines that the phase of the coil current Iu approximately matches the phase of the induced voltage of the U-phase coil Lu, and outputs a phase adjustment instruction signal Sp to the drive control signal generating unit 16 instructing that neither advance angle adjustment nor retard angle adjustment be performed.

[0126] The drive control signal generating unit 16 generates a drive control signal Sd so as to reduce the difference between the zero-cross point Q of the coil current Iu and the zero-cross target point P, based on at least one of the phase adjustment instruction signal Sp and the frequency adjustment instruction signal Sf input from the adjustment instruction signal generating unit 15. Specifically, the PWM command unit 17 determines the setting values ​​of the phase and frequency of the PWM signal, based on at least one of the phase adjustment instruction signal Sp and the frequency adjustment instruction signal Sf generated by the adjustment instruction signal generating unit 15, and determines (generates) a manipulated variable S3 including values ​​of the PWM period and the on-period of the PWM signal, and outputs the manipulated variable S3 to the PWM signal generating unit 18.

[0127] Here, the setting value of the phase of the PWM signal is a value that specifies the time shift width (offset time) from a reference time for outputting a PWM signal as the drive control signal Sd.

[0128] For example, when a phase adjustment instruction signal Sp instructing to perform an advance angle adjustment to advance the angle by only the phase difference Δφ is output from the adjustment instruction signal generating unit 15, the PWM command unit 17 calculates a value "-Δtφ" instructing to output a PWM signal earlier than the reference time by a time Δtφ corresponding to the phase difference Δφ, and sets this value as the setting value for the phase of the PWM signal.

[0129] Also, for example, when a phase adjustment instruction signal Sp instructing to perform a delay adjustment to delay the angle by only the phase difference Δφ is output from the adjustment instruction signal generating unit 15, the PWM command unit 17 calculates a value "+Δtφ" instructing to output a PWM signal later than the reference time by a time Δtφ corresponding to the phase difference Δφ, and sets this value as the setting value for the phase of the PWM signal.

[0130] Also, for example, when a phase adjustment instruction signal Sp that does not instruct the execution of either an advance angle adjustment or a delay angle adjustment is output by the phase adjustment instruction signal Sp from the adjustment instruction signal generating unit 15, the PWM command unit 17 sets the setting value of the phase of the PWM signal to “0 (zero).”

[0131] When outputting the drive control signal Sd, the PWM signal generating unit 18 changes the timing of outputting the drive control signal Sd based on the setting value of the phase of the PWM signal included in the operation amount S3. For example, a reference time for outputting the drive control signal Sd is set in advance, and the PWM signal generating unit 18 outputs the drive control signal Sd at a timing shifted from the reference time by the time specified by the setting value of the phase of the PWM signal.

[0132] For example, when the set value of the phase of the PWM signal is “+Δtφ”, the PWM signal generating unit 18 outputs the drive control signal Sd generated based on the information of the PWM cycle and on-period contained in the operation amount S3, delayed by Δtφ from the reference time.

[0133] For example, when the set value of the phase of the PWM signal is “−Δtφ”, the PWM signal generating unit 18 outputs the drive control signal Sd generated based on the PWM cycle and on-period information contained in the operation amount S3 earlier than the reference time by Δtφ.

[0134] Also, for example, when the set value of the phase of the PWM signal is "0 (zero)", the PWM signal generating unit 18 outputs the drive control signal Sd generated based on the information of the PWM cycle and the on-period included in the manipulated variable S3 at the reference time without shifting the output timing. Note that not shifting the output timing means that if a phase adjustment (advance angle, delay angle adjustment) is being performed at that time, that phase adjustment is maintained.

[0135] Next, a flow of drive control of the motor 5 by the motor drive control device 1 according to this embodiment will be described.

[0136] FIG. 8 is a flowchart showing the flow of the motor drive control process by the motor drive control device 1 according to the embodiment.

[0137] For example, when a DC voltage Vdd is applied to the motor drive control device 1 and the motor drive control device 1 starts up, the motor drive control device 1 first determines whether or not a drive command signal Sc has been input (step S1). If it is determined that the drive command signal Sc has not been input (step S1: NO), the motor drive control device 1 waits until the drive command signal Sc is input.

[0138] When it is determined that the drive command signal Sc has been input (step S1: YES), the motor drive control device 1 starts drive control of the motor 5 (step S2). Specifically, the drive control signal generating unit 16 determines a PWM period and an on-period based on the target rotation speed S1 of the motor 5 analyzed by the drive command analyzing unit 11, generates six types of PWM signals Suu etc. having the determined PWM period and on-period, and inputs them as drive control signals Sd to the drive circuit 3. As a result, the drive circuit 3 switches the energization direction of the coils Lu, Lv, Lw of the motor 5 to rotate the motor 5.

[0139] Next, the motor drive control device 1 determines a target point P of the zero crossing of the U-phase coil current Iu (step S3). For example, as described above, the target point determination unit 12 determines the timing that is 30 electrical degrees ahead of the rising edge of the position detection signal Shu as the target point P (see FIG. 3).

[0140] Next, the motor drive control device 1 estimates the zero-cross point Q of the U-phase coil current Iu (step S4).

[0141] FIG. 9 is a flowchart showing the flow of the process (step S4) of estimating the zero-cross point Q of the U-phase coil current Iu in FIG.

[0142] In the process of estimating the zero-cross point Q of the coil current Iu (step S4), first, the current zero-cross point estimator 14 determines whether the duty ratio of the PWM signal Suu that drives the U-phase high-side switch QuH is 0% (step S41).

[0143] If the duty ratio of the PWM signal Suu is 0% (step S41: YES), the current zero-cross point estimator 14 determines that the U-phase coil current Iu is negative (step S44). If the duty ratio of the PWM signal Suu is not 0% (step S41: NO), the current zero-cross point estimator 14 calculates the difference |Th-Tv| between the on-period Tv during which the drive voltage Vu of the U-phase coil Lu is at a high level and the on-period Th during which the PWM signal Suu of the U-phase high-side switch QuH is at a high level, and determines whether the difference |Th-Tv| is equal to or greater than a threshold value Tth (step S42).

[0144] If it is determined that the difference |Th-Tv| between the on-period Tv and the on-period Th is greater than or equal to the threshold value Tth (step S42: YES), the current zero-cross point estimation unit 14 determines that the on-period Tv and the on-period Th do not match (are mismatched), and determines that the U-phase coil current Iu is negative (step S44).

[0145] On the other hand, if it is determined that the difference |Th-Tv| between the on-period Tv and the on-period Th is less than the threshold value Tth (step S42: NO), the current zero-cross point estimation unit 14 determines that the on-period Tv and the on-period Th match, and determines that the U-phase coil current Iu is positive (step S43).

[0146] After step S43 or step S44, the current zero cross point estimator 14 determines whether or not the polarity of the coil current Iu of the motor 5 has switched (step S45). For example, the current zero cross point estimator 14 determines whether or not the polarity of the coil current Iu determined in step S43 or step S44 differs from the polarity of the coil current Iu determined in the previous step S43 or step S44.

[0147] If it is determined that the polarity of the coil current Iu has not switched (step S45: NO), that is, if the polarity of the coil current Iu determined in step S43 or step S44 matches the polarity of the coil current Iu determined in the previous step S43 or step S44, the current zero cross point estimation unit 14 returns to step S41 and re-executes the processing from steps S41 to S45.

[0148] On the other hand, when it is determined that the polarity of the coil current Iu has been switched (step S45: YES), that is, when the polarity of the coil current Iu determined in step S43 or step S44 does not match the polarity of the coil current Iu determined in the previous step S43 or step S44, the current zero cross point estimation unit 14 estimates the zero cross point Q of the U-phase coil current Iu (step S46). For example, the current zero cross point estimation unit 14 determines a point within a period (zero cross point existence range) Tz1 (or Tz2) between the time when step S43 or step S44 is executed and the time when the immediately preceding step S43 or step S44 is executed as the zero cross point Q of the U-phase coil current Iu (see FIG. 4A or FIG. 4B). This ends the process of step S4.

[0149] As shown in FIG. 8, after step S4 is completed, the motor drive control device 1 adjusts the coil current of the motor 5 (step S5).

[0150] FIG. 10 is a flowchart showing the flow of the coil current adjustment process (step S5) of the motor 5 in FIG.

[0151] In the coil current adjustment process (step S5), first, the adjustment instruction signal generating unit 15 calculates the phase difference Δφ (=phase at time tp−phase at time tq) between the target point P determined in step S3 and the zero-cross point Q of the U-phase coil current Iu estimated in step S4 (step S51).

[0152] Next, the adjustment instruction signal generating unit 15 determines whether the phase difference Δφ calculated in step S51 is within the second range E2 (whether the zero cross point Q of the U-phase coil current Iu is between phase positions T2 and T3) (step S52). When the adjustment instruction signal generating unit 15 determines that the calculated phase difference Δφ is not within the second range E2 (step S52: NO), it further determines whether the calculated phase difference Δφ is outside the first range E1 (whether the zero cross point Q of the U-phase coil current Iu is outside the phase position T1 or outside T4) (step S53).

[0153] If the adjustment instruction signal generating unit 15 determines that the calculated phase difference Δφ is outside the first range E1 (step S53: YES), it decides to perform phase adjustment and permits the phase adjustment (step S54). The adjustment instruction signal generating unit 15 further checks whether the phase adjustment is permitted (step S55), and if it determines that the phase adjustment is not permitted (step S55: NO), it returns to step S51 again.

[0154] On the other hand, when it is determined that the phase adjustment is permitted (step S55: YES), the adjustment instruction signal generating unit 15 determines whether or not the phase difference Δφ calculated in step S51 is equal to or greater than the threshold value +φth (step S56). When it is determined that the phase difference Δφ is equal to or greater than the threshold value +φth (step S56: YES), the adjustment instruction signal generating unit 15 determines that the phase of the coil current Iu leads the phase of the induced voltage of the U-phase coil Lu, and generates a phase adjustment instruction signal Sp that instructs the drive control signal generating unit 16 to perform a delay adjustment to delay the phase of the coil current Iu (step S57). As a result, as described above, the drive control signal generating unit 16 outputs the drive control signal Sd at a timing delayed from the reference time by the time Δtφ corresponding to the phase difference Δφ.

[0155] On the other hand, when it is determined in step S56 that the phase difference Δφ is less than the threshold value +φth (step S56: NO), the adjustment instruction signal generating unit 15 determines whether the phase difference Δφ is less than the threshold value -φth (step S58). When the phase difference Δφ is less than the threshold value -φth (step S58: YES), the adjustment instruction signal generating unit 15 determines that the phase of the coil current Iu lags behind the phase of the induced voltage of the U-phase coil Lu, and generates a phase adjustment instruction signal Sp that instructs the drive control signal generating unit 16 to perform an advance adjustment to advance the phase of the coil current Iu (step S59). As a result, as described above, the drive control signal generating unit 16 outputs the drive control signal Sd at a timing earlier than the reference time by the time Δtφ corresponding to the phase difference Δφ.

[0156] On the other hand, if it is determined in step S58 that the phase difference Δφ is greater than the threshold value −φth (step S58: NO), the adjustment instruction signal generating unit 15 determines that the zero cross point Q of the coil current Iu is within the target range of the target point P, and does not generate a phase adjustment instruction signal Sp that instructs the drive control signal generating unit 16 to adjust the phase of the coil current Iu (step S61). As a result, as described above, the drive control signal generating unit 16 outputs the drive control signal Sd at the reference time without shifting the output timing. This completes the process in step S5.

[0157] If the adjustment instruction signal generator 15 determines that the calculated phase difference Δφ is not outside the first range E1 (step S53: NO), it decides to perform frequency adjustment and executes the process of frequency adjustment 1 shown in FIG. 10 (step S60).

[0158] FIG. 11 is a diagram showing the process (step S60) of frequency adjustment 1 in FIG.

[0159] 11 is a frequency adjustment process executed by the adjustment instruction signal generator 15 when the phase difference Δφ is within the first range E1 and outside the second range E2.

[0160] The adjustment instruction signal generating unit 15 counts up a counter at a predetermined time interval (step S71), and determines whether the counter has reached a certain value or more (step S72). If the adjustment instruction signal generating unit 15 determines that the counter has reached a certain value or more (step S72: YES), it permits phase adjustment (step S73) and clears the counter (step S74).

[0161] On the other hand, if the adjustment instruction signal generator 15 determines that the counter is not equal to or greater than the certain value (step S72: NO), it ends the frequency adjustment 1 process (step S60). However, since phase adjustment is not permitted, the process is executed again from step S71, which is the first step of the frequency adjustment 1 process.

[0162] After clearing the counter in step S74, the adjustment instruction signal generator 15 determines whether the phase difference Δφ is outside the third range E3 (step S75). Since it has already been determined in step S52 that the phase difference Δφ is not within the second range E2, this process may be omitted in the frequency adjustment 1 process. When the adjustment instruction signal generator 15 determines that the phase difference Δφ is not outside the third range E3 (step S75: NO), the process proceeds to step S55 in FIG. 10.

[0163] When the adjustment instruction signal generating unit 15 determines that the phase difference Δφ is outside the third range E3 (step S75: YES), it determines whether or not the currently set control is frequency-up control (step S76). The frequency control is performed within a frequency range set so that the rotation of the motor does not become unstable. There are frequency-up control, which performs processing to increase (upgrade) the frequency by the minimum unit, and frequency-down control, which performs processing to decrease (downgrade) the frequency by the minimum unit. In the initial state, it is set to frequency-up control.

[0164] When it is determined that the frequency increase control is to be executed (step S76: YES), the adjustment instruction signal generating unit 15 generates a frequency adjustment instruction signal Sf for increasing (increasing) the frequency of the PWM signal by only the minimum unit (step S77). The adjustment instruction signal generating unit 15 determines whether the frequency has reached the maximum value of the set range (step S78), and when it is determined that the maximum value has not been reached (step S78: NO), the adjustment instruction signal generating unit 15 proceeds to step S55 in FIG.

[0165] When it is determined that the frequency has reached the maximum value of the setting range (step S78: YES), the adjustment instruction signal generator 15 switches from frequency-up control to frequency-down control (step S79) and proceeds to step S55 in FIG. 10.

[0166] If the adjustment instruction signal generating unit 15 determines that the control is not frequency up control (step S76: NO), it generates a frequency adjustment instruction signal Sf for decreasing (reducing) the frequency of the PWM signal by only the minimum unit (step S80). The adjustment instruction signal generating unit 15 determines whether the frequency has reached the minimum value of the set range (step S81), and if it determines that the minimum value has not been reached (step S81: NO), it proceeds to step S55 in Fig. 10. If the adjustment instruction signal generating unit 15 determines that the frequency has reached the minimum value of the set range (step S81: YES), it switches from frequency down control to frequency up control (step S82) and proceeds to step S55 in Fig. 10.

[0167] In FIG. 10, when the adjustment instruction signal generating unit 15 determines that the calculated phase difference Δφ is within the second range E2 (step S52: YES), it prohibits the phase adjustment (step S62), decides to perform frequency adjustment, and executes the process of frequency adjustment 2 shown in FIG. 12 (step S63).

[0168] FIG. 12 is a diagram showing the process (step S63) of frequency adjustment 2 in FIG.

[0169] 12 is a frequency adjustment process executed by the adjustment instruction signal generator 15 when the phase difference Δφ is within the second range E2. The frequency adjustment 2 process shown in FIG 12 executes substantially the same processes as those in the frequency adjustment 1 process shown in FIG 11, except that the process of step S73 (processing to permit phase adjustment) is omitted.

[0170] The adjustment instruction signal generating unit 15 counts up a counter at a predetermined time interval (step S91), and determines whether the counter has reached a certain value or more (step S92). If the adjustment instruction signal generating unit 15 determines that the counter has reached a certain value or more (step S92: YES), it clears the counter (step S94).

[0171] On the other hand, if the adjustment instruction signal generator 15 determines that the counter is not equal to or greater than the certain value (step S92: NO), it ends the processing of frequency adjustment 2. However, since phase adjustment is not permitted, the processing from step S91, which is the first step of the processing of frequency adjustment 2, is executed again.

[0172] After clearing the counter in step S94, the adjustment instruction signal generating unit 15 determines whether or not the phase difference Δφ is outside the third range E3 (step S95).

[0173] When the adjustment instruction signal generating unit 15 determines that the phase difference Δφ is outside the third range E3 (step S95: YES), it determines whether the currently set control is the frequency-up control (step S96).

[0174] When the adjustment instruction signal generating unit 15 determines that the frequency up control is to be executed (step S96: YES), it generates a frequency adjustment instruction signal Sf for increasing (increasing) the frequency of the PWM signal by only the minimum unit (step S97). The adjustment instruction signal generating unit 15 determines whether the frequency has reached the maximum value of the set range (step S98), and when it determines that the maximum value has not been reached (step S98: NO), it proceeds to step S55 in Fig. 10. When the adjustment instruction signal generating unit 15 determines that the frequency has reached the maximum value of the set range (step S98: YES), it switches from frequency up control to frequency down control (step S99) and proceeds to step S55 in Fig. 10.

[0175] When the adjustment instruction signal generating unit 15 determines that the control is not frequency up control (step S96: NO), it generates a frequency adjustment instruction signal Sf for decreasing (reducing) the frequency of the PWM signal by only the minimum unit (step S100). The adjustment instruction signal generating unit 15 determines whether the frequency has reached the minimum value of the set range (step S101), and when it determines that the minimum value has not been reached (step S101: NO), it proceeds to step S55 in Fig. 10. When the adjustment instruction signal generating unit 15 determines that the frequency has reached the minimum value of the set range (step S101: YES), it switches from frequency down control to frequency up control (step S102) and proceeds to step S55 in Fig. 10.

[0176] If the adjustment instruction signal generator 15 determines that the phase difference Δφ is not outside the third range E3 (step S95: NO), the process proceeds to step S55 in Fig. 10. If the adjustment instruction signal generator 15 determines that the phase difference Δφ is not outside the third range E3, it can be said that the phase difference Δφ is within the third range in which adjustment is not necessary, and therefore the frequency adjustment can be terminated.

[0177] 8, after step S5 is completed, the motor drive control device 1 returns to step S2 and repeats the processes of steps S2 to S6, thereby allowing the motor 5 to continue rotating without a decrease in drive efficiency.

[0178] FIG. 13 is a timing chart showing changes in the voltage of each signal and the coil current when the motor drive control device 1 according to the embodiment adjusts the frequency and phase of the coil current of the motor 5.

[0179] In the figure, the states of the voltages and currents of the motor unit 100 when the motor drive control device 1 executes phase adjustment of the coil current Iu of the U-phase of the motor 5 are shown.

[0180] 13, the waveforms of the position detection signal (Hall signal) Shu, the PWM signal Suu of the U-phase high-side switch QuH, the U-phase drive voltage Vu, the zero-crossing point detection signal Sct, and the U-phase coil current Iu are shown in this order from top to bottom. In addition, in FIG. 13, the horizontal axis represents time, and the vertical axis represents voltage or current.

[0181] 13, a zero-cross point Q where the U-phase coil current Iu switches from negative to positive is detected at time t1, and it can be seen that the frequency and phase of the coil current Iu are adjusted so that the zero-cross point Q coincides with a target range (zero-cross target point P of the U-phase coil current Iu) located at a position where the phase is advanced by an electrical angle of 30 degrees from the rising edge of the position detection signal (Hall signal) Shu. This causes the induced voltage of the motor 5 to approximately coincide in phase with the coil current Iu, making it possible to improve the driving efficiency of the motor 5.

[0182] As described above, the motor drive control device 1 according to this embodiment determines the zero-cross target point P (point at time tp) of the coil current of a predetermined phase based on the position detection signal Shu synchronized with the induced voltage of the coil of a predetermined phase of the motor 5, and estimates the zero-cross point Q (point at time tq) of the coil current of the predetermined phase by detecting a change in the current direction of the coil current of the predetermined phase at a predetermined timing for each cycle of the PWM signal. The motor drive control device 1 generates at least one of a phase adjustment instruction signal (Sp) that instructs phase adjustment of the coil current and a frequency adjustment instruction signal (Sf) that instructs frequency adjustment of the PWM signal according to the phase difference Δφ so that the phase difference Δφ (=phase at time tp-phase at time tq) between the estimated zero-cross point Q of the coil current of the predetermined phase and the zero-cross target point P is within a predetermined range, and generates a drive control signal Sd (PWM signal) for driving the motor 5 based on at least one of the generated phase adjustment instruction signal (Sp) and frequency adjustment instruction signal (Sf).

[0183] As described above, the on-period (first period) Tv of the drive voltage of the coil of a predetermined phase is compared with the on-period (second period) Th of the signal that turns on and off the high-side switch that drives the coil of the predetermined phase, and the zero-cross point Q (tq) of the coil current of the predetermined phase is estimated. In addition, by disposing a position detector 6 (Hall element) at a position corresponding to the coil of a predetermined phase of the motor 5, a position detection signal Shu synchronized with the induced voltage of the coil of the predetermined phase can be obtained. Then, if the phase difference between the position detection signal Shu and the induced voltage is known, it is possible to determine the zero-cross point of the induced voltage, i.e., the target point P of the zero-cross of the coil current of the predetermined phase of the motor 5, based on the rising edge or falling edge of the position detection signal Shu.

[0184] Furthermore, as described above, during a period in which the coil current of a specified phase (e.g., the U phase) of the motor 5 has a positive (+) polarity, the on-period Tv and the on-period Th coincide, and during a period in which the coil current has a negative (-) polarity, the on-period Tv and the on-period Th do not coincide. Therefore, by comparing the on-period Tv and the on-period Th, it is possible to detect the zero-crossing point at which the coil current switches from positive to negative polarity or the zero-crossing point at which the coil current switches from negative to positive polarity.

[0185] Specifically, the motor drive control device 1 determines whether the on-period Tv and the on-period Th coincide with each other, and detects at least one of the timing when the on-period Tv and the on-period Th switch from a coincident state to a non-coincident state and the timing when the on-period Tv and the on-period Th switch from a non-coincident state to a coincident state, and estimates the detected timing as the zero-crossing point of the coil current of a specified phase. According to this, even if the coil current of the motor 5 is not directly monitored, the zero crossing point of the coil current can be easily estimated.

[0186] The motor drive control device 1 adjusts the coil current in accordance with the phase difference Δφ between the zero-cross target point P of the coil current of a specified phase and the zero-cross point Q of the coil current of a specified phase, thereby reducing the phase difference between the phase of the induced voltage of the coil of a specified phase of the motor and the phase of the coil current.

[0187] As described above, according to the motor drive control device 1 of the present embodiment, the accuracy of phase adjustment is increased without destabilizing the rotation speed of the motor 5, making it possible to improve the drive efficiency of the motor.

[0188] Furthermore, the motor drive control device 1 synchronizes the PWM signal with the position detection signal at a timing before the zero-cross point of the coil current of a predetermined phase is estimated in the control circuit.

[0189] This stabilizes the position of the PWM signal with respect to the target point P of the zero crossing of the coil current, which is determined from the position detection signal for each adjustment period, and facilitates adjustment.

[0190] In addition, in the motor drive control device 1, when the phase difference is outside the first range, the adjustment instruction signal generating unit 15 generates only a phase adjustment instruction signal until the phase difference falls within the first range, and when the phase difference falls within the first range, generates at least one of a frequency adjustment instruction signal and a phase adjustment instruction signal. According to this, when the phase difference is large, the phase difference can be efficiently reduced by performing only the phase adjustment.

[0191] Furthermore, when the phase difference is within a second range inside the first range, the adjustment instruction signal generating section 15 of the motor drive control device 1 prohibits generation of a phase adjustment instruction signal and generates only a frequency adjustment instruction signal. According to this, when the phase difference is relatively small, the phase adjustment is prohibited and only the frequency adjustment is performed, so that fine adjustment of the phase difference can be stably performed.

[0192] Furthermore, the motor drive control device 1 instructs the adjustment instruction signal generating unit 15 to adjust the frequency of the PWM signal for each minimum frequency unit by a frequency adjustment instruction signal, and generates frequency adjustment instruction signals at predetermined time intervals. With this, even if it takes time for the rotation to stabilize after the frequency is changed, the rotation does not become unstable and the phase does not shift significantly, and the frequency can be adjusted while stabilizing the rotation.

[0193] In addition, the motor drive control device 1 instructs, in the adjustment instruction signal generating unit 15, by a frequency adjustment instruction signal, to increase the frequency of the PWM signal until it reaches the maximum frequency within a specified frequency range, or to decrease the frequency of the PWM signal until it reaches the minimum frequency within the specified frequency range. According to this, by setting the specified frequency range to an appropriate range where the phase adjustment control is thought to be stable, it becomes possible to perform the phase adjustment quickly, and by adjusting by gradually increasing or decreasing, the change in duty becomes gradual, and it is possible to suppress abrupt changes in the current and rotation speed.

[0194] Furthermore, in the motor drive control device 1, when the phase difference falls within a third range inside the second range, the adjustment command signal generating section 15 ends generation of the frequency adjustment command signal. This allows the phase difference to be adjusted to a desired value.

[0195] In addition, the motor drive control device 1 has a drive control signal generating unit that has a PWM command unit that generates a manipulated variable for the drive control signal, and a PWM signal generating unit that generates a drive control signal based on the manipulated variable, and the PWM command unit has a rotational speed setting unit that determines a rotational speed setting value based on a rotational speed command value and the current rotational speed, a phase setting unit that determines a phase setting value based on a phase adjustment instruction signal, a frequency setting unit that determines a frequency setting value based on a frequency adjustment instruction signal, and a manipulated variable determination unit that determines the manipulated variable based on the determined rotational speed setting value, phase setting value, and frequency setting value.

[0196] This makes it possible to generate a drive control signal that satisfies any of the rotation speed command, phase command, and frequency command.

[0197] <<Extension of the embodiment>> The invention made by the inventor has been specifically described above based on an embodiment, but it goes without saying that the invention is not limited thereto and can be modified in various ways without departing from the spirit of the invention.

[0198] For example, in the above embodiment, the position detector 6 is arranged for the coil of the U phase among the three phases (U phase, V phase, and W phase) of the motor 5, and the zero cross point of the drive voltage Vu and the coil current Iu of the U phase is detected, but the present invention is not limited to this. The position detector 6 may be arranged for the coil Lv of the V phase to detect the zero cross point of the drive voltage Vv and the coil current Iv of the V phase to adjust the phase of the coil current Iv, or the position detector 6 may be arranged for the coil Lw of the W phase to detect the zero cross point of the drive voltage Vw and the coil current Iw of the W phase to adjust the phase of the coil current Iw. Furthermore, the position detector 6 may be arranged for two or all of the U phase, V phase, and W phase to detect the zero cross point of the drive voltage and the coil current of any of the phases, and adjust the phase of the coil current of the detected phase.

[0199] In the above embodiment, the current zero cross point estimation unit 14 detects both the timing when the on-period (first period Tv) of the drive voltage Vu of the coil Lu and the on-period (second period Th) of the PWM signal of the U-phase high-side switch switch from a matching state to a non-matching state (zero cross point Q at which the coil current Iu switches from positive to negative) and the timing when the on-period Tv and the on-period Th switch from a non-matching state to a matching state (zero cross point Q at which the coil current Iu switches from negative to positive), but it may detect either one of the zero cross points Q. For example, the current zero cross point estimation unit 14 may detect only the zero cross point Q at which the coil current Iu switches from negative to positive.

[0200] In the above embodiment, the type of motor 5 is not limited to a brushless DC motor. Also, the motor 5 is not limited to a three-phase motor, and may be, for example, a single-phase brushless DC motor.

[0201] In the above embodiment, a Hall element is used as the position detector 6, but this is not limiting. For example, a Hall IC, an encoder, a resolver, or the like may be provided as the position detector 6, and the detection signal thereof may be input to the motor drive control device 1 as the position detection signal Shu.

[0202] Furthermore, the above-described flowcharts are merely examples and are not intended to be limiting. For example, other processes may be inserted between each step, or the processes may be parallelized. [Explanation of symbols]

[0203] 1...motor drive control device, 2...control circuit, 3...drive circuit, 4...phase voltage detection circuit, 5...motor, 6...position detector, 11...drive command analysis unit, 12...target point determination unit, 13...phase voltage input unit, 14...current zero cross point estimation unit, 15...adjustment instruction signal generation unit, 16...drive control signal generation unit, 17...PWM command unit, 171...rotation speed setting unit, 172...phase setting unit, 173...frequency setting unit, 174...operation amount determination unit, 18...PWM signal signal generating unit, 100... motor unit, 200... waveform of position detection signal Shu, 201... waveform of drive voltage Vu of U-phase coil Lu, 202... waveform of induced voltage of U-phase coil Lu, 203... waveform of coil current Iu of U-phase coil Lu, Lu, Lv, Lw... coil, Iu... U-phase coil current, S1... target rotation speed, S3... operation amount, Sc... drive command signal, Sct... zero-cross point detection signal, Shu... position detection signal, Sp... position Phase adjustment instruction signal, Sf...frequency adjustment instruction signal, Sd...drive control signal, Suu, Sul, Svu, Svl, Swu, Swl...PWM signal, Tv...on period (first period) of drive voltage Vu of coil Lu, Th...on period (second period) of PWM signal Suu, Td...dead time period, Tz1, Tz2...range of zero crossing points, T1, T1A, T2, T2A, T3, T4...phase position, E1...first range (of phase difference), E2 ...second range (of phase difference), E3...third range (of phase difference), QuH, QvH, QwH...high-side switches, QuL, QvL, QwL...low-side switches, Δφ...phase difference, +φth, -φth...threshold, Tth...threshold, Vu...driving voltage of coil Lu, Vv...driving voltage of coil Lv, Vw...driving voltage of coil Lw, Vdd DC voltage, P...target point of zero crossing of coil current Iu, Q...zero crossing point of coil current Iu.

Claims

1. A control circuit that generates a drive control signal, which is a PWM signal for driving a motor having at least one phase coil; a drive circuit including a high-side switch and a low-side switch connected in series to each other and provided corresponding to a coil of each phase of the motor, and alternately turning on and off the high-side switch and the low-side switch in response to the drive control signal to switch a current direction of the coil of the corresponding phase; The control circuit includes: a target point determination unit that is synchronized with an induced voltage in a coil of a predetermined phase of the motor and determines a target point of a zero cross of a coil current of the predetermined phase based on a position detection signal corresponding to a rotational position of a rotor of the motor; a current zero cross point estimating unit that estimates a zero cross point of a coil current of the predetermined phase by detecting a change in a current direction of the coil current of the predetermined phase at a predetermined timing for each cycle of the PWM signal; an adjustment instruction signal generation unit that generates at least one of a phase adjustment instruction signal that instructs phase adjustment of the coil current and a frequency adjustment instruction signal that instructs frequency adjustment of the PWM signal in accordance with a phase difference between the target point determined by the target point determination unit and the zero cross point estimated by the current zero cross point estimation unit so that the phase difference falls within a predetermined range; a drive control signal generation unit that generates the drive control signal based on at least one of the phase adjustment instruction signal and the frequency adjustment instruction signal generated by the adjustment instruction signal generation unit, the current zero crossing point estimator compares at least one of an on-period and an off-period of a drive voltage for a coil of the predetermined phase with at least one of an on-period and an off-period of a signal for turning on and off the high-side switch corresponding to the predetermined phase, and detects a change in the current direction of the coil current of the predetermined phase based on a result of the comparison; The control circuit synchronizes the PWM signal with the position detection signal at a timing before estimating a zero cross point of the coil current of the predetermined phase. Motor drive control device.

2. 2. The motor drive control device according to claim 1, When the phase difference is outside a first range, the adjustment instruction signal generation unit generates only the phase adjustment instruction signal until the phase difference falls within the first range, and when the phase difference falls within the first range, generates at least one of the frequency adjustment instruction signal and the phase adjustment instruction signal. Motor drive control device.

3. 3. The motor drive control device according to claim 2, When the phase difference is within a second range inside the first range, the adjustment instruction signal generation unit prohibits generation of the phase adjustment instruction signal and generates only the frequency adjustment instruction signal. Motor drive control device.

4. 4. The motor drive control device according to claim 2, The adjustment instruction signal generating unit instructs, by the frequency adjustment instruction signal, to adjust the frequency of the PWM signal for each minimum frequency unit, and generates the frequency adjustment instruction signal at predetermined time intervals. Motor drive control device.

5. 5. The motor drive control device according to claim 4, The adjustment instruction signal generating unit instructs, by the frequency adjustment instruction signal, to increase the frequency of the PWM signal until it reaches a maximum frequency within a predetermined frequency range, or instructs to decrease the frequency of the PWM signal until it reaches a minimum frequency within the predetermined frequency range. Motor drive control device.

6. 4. The motor drive control device according to claim 3, The adjustment instruction signal generating unit terminates generation of the frequency adjustment instruction signal when the phase difference falls within a third range inside the second range. Motor drive control device.

7. The motor drive control device according to any one of claims 1 to 6, the drive control signal generating unit has a PWM command unit that generates an operation amount of the drive control signal, and a PWM signal generating unit that generates the drive control signal based on the operation amount; The PWM command unit has a rotation speed setting unit that determines a rotation speed setting value based on a rotation speed command value and a current rotation speed, a phase setting unit that determines a phase setting value based on the phase adjustment instruction signal, a frequency setting unit that determines a frequency setting value based on the frequency adjustment instruction signal, and a manipulated variable determination unit that determines the manipulated variable based on the determined rotation speed setting value, phase setting value, and frequency setting value. Motor drive control device.

8. A motor drive control device according to any one of claims 1 to 7, The motor. Motor unit.

9. A motor control method using a motor drive control device including: a control circuit that generates a drive control signal, which is a PWM signal for driving a motor having a coil of at least one phase; and a drive circuit that includes a high-side switch and a low-side switch that are connected in series to each other and are provided corresponding to the coil of each phase of the motor, and that alternately turns on and off the high-side switch and the low-side switch in response to the drive control signal to switch a current flow direction of the coil of the corresponding phase, a first step in which the control circuit determines a zero-cross target point of a coil current of a predetermined phase of the motor based on a position detection signal that is synchronized with an induced voltage of the coil of the predetermined phase of the motor and corresponds to a rotational position of a rotor of the motor; A second step in which the control circuit detects a change in the current direction of the coil of the predetermined phase at a predetermined timing for each cycle of the PWM signal, thereby estimating a zero cross point of the coil current of the predetermined phase; a third step in which the control circuit generates at least one of a phase adjustment instruction signal for instructing phase adjustment of the coil current and a frequency adjustment instruction signal for instructing frequency adjustment of the PWM signal in response to a phase difference between the target point determined in the first step and the zero cross point estimated in the second step so that the phase difference falls within a predetermined range; a fourth step of the control circuit generating the drive control signal based on at least one of the phase adjustment instruction signal and the frequency adjustment instruction signal generated in the third step, In the second step, at least one of an on-period and an off-period of a drive voltage for a coil of the predetermined phase is compared with at least one of an on-period and an off-period of a signal for turning on and off the high-side switch corresponding to the predetermined phase, and a change in a current direction of the coil current of the predetermined phase is detected based on a result of the comparison; The control circuit synchronizes the PWM signal with the position detection signal at a timing before estimating a zero cross point of the coil current of the predetermined phase. A motor drive control method.

Images