Motor driver circuit and driving method

Abstract

To provide a motor driver circuit and a driving method capable of accurately detecting the position of a rotor.SOLUTION: A motor driver circuit for driving a three phase brushless motor includes a phase signal generator 250. The phase signal generator 250 generates a current phase signal φ indicating the position of the rotor of the three phase brushless motor based on the U-phase Hall signal HU, the V-phase Hall signal HV, and the W-phase Hall signal HW. The phase signal generator 250 generates a reference phase signal θ that discretely changes in response to edges of the three phase Hall signals HU, HV, and HW, and calculates an error signal err = sin θ * cos φ - cos θ * sin φ. The phase signal generator 250 calculates the error signal err by the loop filter 266. The phase signal generator 250 integrates the output of the loop filter 266 to generate a current phase signal φ.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a driving technique for a three-phase brushless motor. [Background technology]

[0002] When driving a three-phase brushless motor, it is necessary to switch the drive phase depending on the rotor position. Three-phase brushless motor drive methods are classified into sensorless control and sensor-based control depending on the rotor position detection method. A typical sensor is a hall sensor, and hall sensor drive uses the output (called a hall signal) of a sensor such as a hall element to detect the rotor position.

[0003] When three-phase Hall elements are installed in the appropriate position relative to the motor to be driven and the magnetic flux of the magnet is ideally magnetized, the three-phase Hall signals have an ideal waveform with a 50% duty cycle and an even phase difference of 120°. However, if the three-phase Hall elements are installed in a misaligned position, the positions of the positive and negative edges of the Hall signal will deviate from the ideal waveform. Driving a motor based on Hall signals with errors can cause noise and vibration. In the 180-degree conduction method (sine wave drive method), the current flowing through the coil is controlled based on a sine wave or similar waveform according to the phase angle. Therefore, the rotor position (phase angle) must be accurately known. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-175328

[0005] [overview] The present disclosure has been made in view of the above-mentioned problems, and one purpose of an embodiment thereof is to provide a motor driver circuit and a driving method that are capable of accurately detecting the position of a rotor.

[0006] One aspect of the present disclosure relates to a motor driver circuit for driving a three-phase brushless motor. The motor driver circuit includes a phase signal generator that generates a current phase signal φ indicating the rotor position of the three-phase brushless motor based on a U-phase Hall signal, a V-phase Hall signal, and a W-phase Hall signal. The phase signal generator performs the following operations in response to edges of the U-phase Hall signal, the V-phase Hall signal, and the W-phase Hall signal: generating a discretely changing reference phase signal θ; calculating an error signal err = sin θ × cos φ - cos θ × sin φ; calculating the error signal err using a loop filter; and integrating the output of the loop filter to generate the current phase signal φ.

[0007] Another aspect of the present disclosure relates to a method for driving a sensor-equipped three-phase brushless motor, the method comprising the steps of generating a current phase signal φ indicating a rotor position of the three-phase brushless motor based on a U-phase Hall signal, a V-phase Hall signal, and a W-phase Hall signal, wherein the step of generating the current phase signal φ includes the steps of generating a reference phase signal θ that changes discretely in response to edges of the U-phase Hall signal, the V-phase Hall signal, and the W-phase Hall signal, calculating an error signal err=sin θ×cos φ−cos θ×sin φ, calculating the error signal err using a loop filter, and integrating an output of the loop filter to generate the current phase signal φ.

[0008] Any combination of the above elements, or mutual substitution of elements or expressions between methods, devices, systems, etc., are also valid aspects of the present invention or the present disclosure. Furthermore, the description in this section (Means for Solving the Problems) does not explain all essential features of the present invention, and therefore, subcombinations of the described features may also constitute the present invention. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a circuit diagram of a motor circuit according to an embodiment. [Figure 2]FIG. 2 is a diagram showing the transition of the three-phase hall signals HU, HV, and HW when the motor is rotating. [Figure 3] FIG. 3 is a functional block diagram of the phase signal generator. [Figure 4] FIG. 4 is a diagram illustrating the operation of the phase signal generator of FIG. [Figure 5] FIG. 5 is a diagram illustrating the phase correction based on the correction value.

[0010] [Detailed explanation] (Outline of the embodiment) A summary of some exemplary embodiments of the present disclosure is provided. This summary is intended to provide a simplified overview of some concepts of one or more embodiments in order to provide a basic understanding of the embodiments as a prelude to the more detailed description that follows. It is not intended to limit the scope of the invention or disclosure. Furthermore, this summary is not an exhaustive overview of all possible embodiments, nor does it limit essential elements of the embodiments. For convenience, the term "one embodiment" may refer to one embodiment (example or variant) or multiple embodiments (examples or variants) disclosed herein.

[0011] A motor driver circuit according to one embodiment drives a three-phase brushless motor. The motor driver circuit includes a phase signal generator that generates a current phase signal φ indicating the rotor position of the three-phase brushless motor based on U-phase, V-phase, and W-phase Hall signals. The phase signal generator performs the following operations in response to edges of the U-phase, V-phase, and W-phase Hall signals: generating a discretely changing reference phase signal θ; calculating an error signal err = sin θ × cos φ - cos θ × sin φ; calculating the error signal err using a loop filter; and integrating the output of the loop filter to generate the current phase signal φ.

[0012] In this configuration, by configuring a PLL circuit that uses the angle information when the edges of the U-phase Hall signal, V-phase Hall signal, and W-phase Hall signal occur as the target value, accurate phase information can be generated without being affected by fluctuations in rotation speed.

[0013] In one embodiment, the integration process may be a first order integration of the output of the loop filter.

[0014] In one embodiment, the integration process may perform a second integration of the output of the loop filter.

[0015] In one embodiment, the reference phase signal θ may take a value in increments of 60° plus a correction value, thereby correcting for positional deviation of the Hall sensor.

[0016] In one embodiment, the loop filter may include a PI (proportional-integral) controller.

[0017] In one embodiment, the phase signal generator includes a CORDIC (Coordinate Rotation Digital Computer), and the table referenced by the CORDIC may also be used as a table for a waveform generator that generates a sine wave, thereby preventing an increase in circuit area.

[0018] In one embodiment, the motor driver circuit may be monolithically integrated on a single semiconductor substrate. "Monolithic integration" includes cases where all of the circuit components are formed on a semiconductor substrate, or where the main circuit components are monolithically integrated, and some resistors and capacitors for adjusting circuit constants may be provided outside the semiconductor substrate. By integrating the circuit on a single chip, the circuit area can be reduced and the characteristics of the circuit elements can be maintained uniformly.

[0019] (Embodiment) Preferred embodiments will be described below with reference to the drawings. The same or equivalent components, parts, and processes shown in each drawing will be designated by the same reference numerals, and redundant descriptions will be omitted where appropriate. Furthermore, the embodiments are merely examples and do not limit the invention, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention.

[0020] In this specification, "a state in which component A is connected to component B" includes not only a case in which component A and component B are directly physically connected to each other, but also a case in which component A and component B are indirectly connected to each other via other components that do not substantially affect the electrical connection between them or that do not impair the function or effect achieved by their connection.

[0021] Similarly, "a state in which component C is provided between component A and component B" includes not only cases in which components A and C, or components B and C, are directly connected, but also cases in which they are indirectly connected via other components that do not substantially affect the electrical connection state between them or impair the functions or effects achieved by their combination.

[0022] 1 is a circuit diagram of a motor circuit 100 according to an embodiment. The motor circuit 100 includes a three-phase brushless motor (hereinafter simply referred to as a motor) 102 and a motor driver circuit 200 that drives the motor 102. The motor 102 is a motor with three Hall sensors, in which three Hall elements 104U, 104V, and 104W are attached. Each of the Hall elements 104U, 104V, and 104W is supplied with a Hall bias voltage V generated by the motor driver circuit 200 or a separate power supply circuit. HB Each Hall element 104 generates a pair of Hall voltages V that indicate the rotor position of the motor 102. H+ ,V H- Output.

[0023] The motor driver circuit 200 drives the motor 102 based on a command from the host controller 106. The motor driver circuit 200 has a U-phase output OUTU, a V-phase output OUTV, and a W-phase output OUTW that are connected to the U-phase, V-phase, and W-phase coils of the motor 102. The motor driver circuit 200 also outputs a Hall voltage V H+ ,V H- The output OUT# (#=U, V, W) of each phase can be high (H), low (L) or high impedance (HiZ). High H can be not only a fixed high but also a PWM modulated state.

[0024] The motor driver circuit 200 includes a controller circuit 210, a pre-driver 220, an inverter circuit 230, and Hall comparators 240U, 240V, and 240W, all of which are monolithically integrated on a single semiconductor substrate. "Monolithically integrated" includes cases where all of the circuit components are formed on the semiconductor substrate, and cases where the main circuit components are monolithically integrated, and some resistors, capacitors, etc. may be provided outside the semiconductor substrate to adjust the circuit constants.

[0025] The power supply (VDD) terminal of the motor driver circuit 200 is supplied with a power supply voltage V from an external power supply (not shown). DD is supplied.

[0026] The Hall comparator 240U detects the Hall voltage V H+ and V H- and generate a Hall signal HU that indicates the magnitude relationship. The Hall signal HU is H+ , V H- The same applies to the Hall comparators 240V and 240W.

[0027] The controller circuit 210 generates a control signal S that controls the state of the inverter circuit 230 based on the Hall signals HU, HV, and HW. CNT For example, the controller circuit 210 generates the control signal SCNT The controller circuit 210 may scale the duty cycle of the PWM control of the motor 102 according to the target rotation speed of the motor 102.

[0028] The pre-driver 220 receives the control signal S generated by the controller circuit 210. CNT The inverter circuit 230 is driven based on this. The inverter circuit 230 is a three-phase inverter and includes a U-phase leg, a V-phase leg, and a W-phase leg. The U-phase leg includes an upper arm UH and a lower arm UL, the V-phase leg includes an upper arm VH and a lower arm VL, and the W-phase leg includes an upper arm WH and a lower arm WL. When the upper arm #H is on and the lower arm #L is off, the output OUT# is high. When the upper arm #H is off and the lower arm #L is on, the output OUT# is low. When both the upper arm #H and the lower arm #L are off, the output OUT# has high impedance.

[0029] In the 120-degree conduction method, the state machine 212 switches the coil (drive phase) to which the drive current is supplied in synchronization with the Hall signals HU, HV, and HW (commutation control).In the 180-degree conduction method and the 150-degree conduction method, the state machine 212 also switches the drive phase based on the output of the angle multiplier circuit synchronized with the Hall signals HU, HV, and HW (commutation control).

[0030] 2 is a diagram showing the transitions of the three-phase Hall signals HU, HV, and HW when the motor 102 is rotating. The three-phase Hall signals HU, HV, and HW are pulse signals whose phases are shifted by 120°, and the positive and negative edges of each Hall signal appear every 60°. The combinations of the three-phase Hall signals HU, HV, and HW cyclically repeat (HLH), (HLL), (HHL), (LHL), (LHH), and (LLH). When the rotation direction is reversed, the transitions occur in the reverse order.

[0031] Returning to Fig. 1, the controller circuit 210 includes a phase signal generator 250 and a waveform generator 280. The controller circuit 210 may be implemented by hardware such as a logic circuit or an FPGA (Field Programmable Gate Array), or may be implemented by a combination of software and a processor.

[0032] The phase signal generator 250 uses the U-phase Hall signal HU, the V-phase Hall signal HV, and the W-phase Hall signal HW to generate a current phase signal φ that indicates the current rotor position. The current phase signal φ is a signal with one cycle of 360°. The waveform generator 280 uses the current phase signal φ in the 180-degree conduction method or the 150-degree conduction method to generate a waveform signal that defines the drive current. The waveform signal can be a sine wave, a pseudo-sine wave, or a trapezoidal wave.

[0033] 3 is a functional block diagram of a phase signal generator 250. The phase signal generator 250 includes a reference phase generator 252, an error detector 254, a loop filter 266, and an integrator 268. As described above, the phase signal generator 250 can also be implemented in software, and therefore the block diagram of FIG. 3 does not necessarily limit the hardware configuration, and may also schematically represent functions executed by software.

[0034] For ease of understanding, the phase is treated as having a minimum value of 0° and a maximum value of 360°, and values ​​exceeding the maximum value or falling below the minimum value are assumed to be wrapped so that they fall within the range of 0° to 360°.

[0035] The reference phase generator 252 generates a reference phase signal θ that changes in 60° increments in response to edges of the three-phase Hall signals HU, HV, and HW. In this embodiment, the current phase signal φ changes within a range of 0° to 360°, and the reference phase signal θ takes on discrete values ​​of 0°, 60°, 120°, 180°, 240°, and 300° depending on the combination of the Hall signals HU, HV, and HW. For example, the relationship between the reference phase signal θ and (HU, HV, HW) is as follows: 1 indicates H and 0 indicates L. For example, the timing when (HU, HV, HW) transition from (0,1,1) to (0,0,1) represents the 60° reference. θ(°) (HU,HV,HW) 0 = (0,1,1) 60 =(0,0,1) 120 = (1,0,1) 180 = (1,0,0) 240 = (1,1,0) 300 = (0,1,0)

[0036] It should be noted that which state is set to 0° is arbitrary. The values ​​of the reference phase signal θ, i.e., 0°, 60°, 120°, 240°, and 300°, are values ​​when the Hall element 104 is ideally attached, and in reality, there are variations due to manufacturing errors. In order to cancel this manufacturing error, the multiple values ​​of the reference phase signal θ are adjusted by using correction constants C0 and C1. 60 ,C 120 ,C 180 ,C 240 ,C 300 The value of the reference phase signal θ after correction is as follows: Correction constants C0 and C 60 ,C 120 ,C 180 ,C 240 ,C 300 can be positive or negative. θ(°) (HU,HV,HW) 0+C0=(0,1,1) 60+C 60 =(0,0,1) 120+C 120 =(1,0,1) 180+C180 =(1,0,0) 240+C 240 =(1,1,0) 300+C 300 =(0,1,0) That is, the reference phase signal θ takes a value obtained by adding the correction value to a value in 60° increments, thereby correcting for any deviation in the mounting position of the Hall element 104.

[0037] The error detector 254 generates an error err between the reference phase signal θ and the current phase signal φ. The error detector 254 calculates the error err based on the following equation: err=sinθ×cosφ-cosθ×sinφ…(1)

[0038] The error detector 254 includes a first sine-cosine converter 256, a second sine-cosine converter 258, a first multiplier 260, a second multiplier 262, and a subtractor 264. The first sine-cosine converter 256 calculates the sine (sin θ) and cosine (cos θ) of the reference phase signal θ. The second sine-cosine converter 258 calculates the sine (sin φ) and cosine (cos φ) of the current phase signal φ.

[0039] The first sine-cosine converter 256 and the second sine-cosine converter 258 can be implemented using hardware called a CORDIC (Coordinate Rotation Digital Computer), and the first sine-cosine converter 256 and the second sine-cosine converter 258 can share a table having constants necessary for calculation. This table can be the same as the table used in the waveform generator 280 to generate a sine wave waveform in the 180-degree conduction method. Therefore, it is possible to suppress an increase in the data capacity of the table due to the provision of the first sine-cosine converter 256 and the second sine-cosine converter 258, and an increase in the circuit area can also be suppressed.

[0040] The first multiplier 260 calculates sin θ × cos φ. The second multiplier 262 calculates cos θ × sin φ. The subtractor 264 calculates err = sin θ × cos φ - cos θ × sin φ. This error signal err is equal to sin(θ - φ), and when θ = φ, err = 0. Therefore, err can be understood to represent the error between θ and φ, i.e., the phase difference, and the error detector 254 can be understood as a phase detector that detects the difference (phase difference) between θ and φ.

[0041] The error detector 254, loop filter 266, and integrator 268 are PLL (Phase Locked Loop) circuits that use quadrature detection. A typical PLL circuit compares the timing of the edges of a periodic signal to be controlled with the timing of the edges of a reference control signal on the time axis, but in this embodiment, the values ​​of φ and θ themselves represent the timing of the edges.

[0042] The loop filter 266 filters the error signal err. The loop filter 266 can be configured with a PI (proportional-integral) controller (also called a compensator). The output signal LFOUT of the loop filter 266 is P and the integral coefficient K I Using this, it can be expressed as equation (2). LFOUT=K P ×err+K I ∫err·dt …(2)

[0043] The integrator 268 integrates the output LFOUT of the loop filter 266 to generate the current phase signal φ. In one embodiment, the integrator 268 may perform a first-order integration of the output LFOUT of the loop filter 266. In this case, the output LFOUT of the loop filter 266 has the dimension of an angular velocity.

[0044] In one embodiment, the integrator 268 may perform a second-order integration of the output LFOUT of the loop filter 266. In this case, the output LFOUT of the loop filter 266 has the dimension of angular acceleration.

[0045] The above is the configuration of the phase signal generator 250. Next, the operation thereof will be explained.

[0046] 4 is a diagram illustrating the operation of the phase signal generator 250 of FIG. REF indicates the actual motor rotor position (angle), and EDGE represents the edges of the Hall signals HU, HV, and HW. Here, the angles are expressed in radians (rad) and vary within the range of -π to π. θ represents the motor position when each edge of the Hall signals HU, HV, and HW occurs.

[0047] LFOUT is the output of the loop filter 266 and indicates the angular velocity. The bottom row indicates sinφ' and cosφ', where φ' is the value obtained by quantizing the current phase signal φ.

[0048] Each time an edge of the Hall signals HU, HV, and HW occurs, the reference phase signal θ is updated, and feedback is applied so that the error between the current phase signal φ and the reference phase signal θ at the updated timing approaches 0. As a result, the actual phase signal φ REF It is possible to generate an accurate current phase signal φ with a small error from the

[0049] FIG. 5 illustrates phase correction based on a correction value. Assume that the U-phase Hall element 104U is installed 5° ahead of the correct position, and the V-phase Hall element 104V is installed 10° behind the correct position. In this case, the values ​​of the reference phase signal θ after correction can be set to 0°, 70°, 115°, 180°, 250°, and 295°. This allows the reference phase signal θ to be generated according to the actual installation positions of the Hall elements at the timing of the edges of the Hall signals HU, HV, and HW, even if the intervals between the Hall signals HU, HV, and HW are not 60°, thereby correcting the positional deviation.

[0050] The embodiments described using specific terms merely illustrate the principles and applications of the present invention, and many modifications and changes in arrangement are permitted to the embodiments as long as they do not deviate from the spirit of the present invention as defined in the claims.

[0051] (Addendum) One aspect of the technology disclosed in this specification can be understood as follows.

[0052] (Item 1) A motor driver circuit for driving a three-phase brushless motor, a phase signal generator that generates a current phase signal φ indicating a rotor position of the three-phase brushless motor based on a U-phase Hall signal, a V-phase Hall signal, and a W-phase Hall signal; The phase signal generator generating a reference phase signal θ that changes discretely in response to edges of the U-phase Hall signal, the V-phase Hall signal, and the W-phase Hall signal; A process of calculating an error signal err=sinθ×cosφ-cosθ×sinφ; A process of calculating the error signal err using a loop filter; an integration process for integrating the output of the loop filter to generate the current phase signal φ; To run the motor driver circuit.

[0053] (Item 2) 2. The motor driver circuit according to item 1, wherein the integration process is a first-order integration of the output of the loop filter.

[0054] (Item 3) 2. The motor driver circuit according to item 1, wherein the integration process performs a second-order integration of the output of the loop filter.

[0055] (Item 4) 4. The motor driver circuit according to any one of items 1 to 3, wherein the reference phase signal θ takes a value obtained by adding a correction value to a value in 60° increments.

[0056] (Item 5) 5. The motor driver circuit according to any one of items 1 to 4, wherein the loop filter includes a PI (proportional-integral) controller.

[0057] (Item 6) The motor driver circuit according to any one of items 1 to 5, wherein the phase signal generator includes a CORDIC (COordinate Rotation Digital Computer), and the table referenced by the CORDIC is also used as a table for a waveform generator that generates a sine wave.

[0058] (Item 7) 7. The motor driver circuit according to any one of items 1 to 6, which is monolithically integrated on a single semiconductor substrate.

[0059] (Item 8) A method for driving a sensor-equipped three-phase brushless motor, comprising: generating a current phase signal φ indicating a rotor position of the three-phase brushless motor based on a U-phase Hall signal, a V-phase Hall signal, and a W-phase Hall signal; The step of generating the current phase signal φ includes: generating a reference phase signal θ that changes discretely in response to edges of the U-phase Hall signal, the V-phase Hall signal, and the W-phase Hall signal; calculating an error signal err=sinθ×cosφ−cosθ×sinφ; calculating the error signal err by a loop filter; an integration step of integrating the output of the loop filter to generate the current phase signal φ; A driving method including:

[0060] (Item 9) 9. The driving method according to item 8, wherein the integration step performs a first-order integration of the output of the loop filter.

[0061] (Item 10) 9. The driving method according to item 8, wherein the integration step performs a second-order integration of the output of the loop filter.

[0062] (Item 11) 11. The driving method according to any one of items 8 to 10, wherein the reference phase signal θ takes a value obtained by adding a correction value to a value in 60° increments.

[0063] (Item 12) 12. The driving method according to any one of items 8 to 11, wherein the loop filter includes a PI (proportional-integral) controller. [Explanation of symbols]

[0064] 100...motor circuit, 102...motor, 104...hall element, 200...motor driver circuit, 210...controller circuit, 220...pre-driver, 230...inverter circuit, 240U, 240V, 240W...hall comparator, 250...phase signal generator, 252...reference phase generator, 254...error detector, 256...first sine-cosine converter, 258...second sine-cosine converter, 260...first multiplier, 262...second multiplier, 264...subtractor, 266...loop filter, 268...integrator, 280...waveform generator.

Claims

1. A motor driver circuit for driving a three-phase brushless motor, a phase signal generator that generates a current phase signal φ indicating a rotor position of the three-phase brushless motor based on a U-phase Hall signal, a V-phase Hall signal, and a W-phase Hall signal; The phase signal generator generating a reference phase signal θ that changes discretely in response to edges of the U-phase Hall signal, the V-phase Hall signal, and the W-phase Hall signal; A process of calculating an error signal err=sin θ×cos φ−cos θ×sin φ; A process of calculating the error signal err using a loop filter; an integration process for integrating the output of the loop filter to generate the current phase signal φ; To run the motor driver circuit.

2. The motor driver circuit according to claim 1 , wherein the integration process performs a first-order integration of the output of the loop filter.

3. The motor driver circuit according to claim 1 , wherein the integration processing is a second-order integration of the output of the loop filter.

4. 4. The motor driver circuit according to claim 1, wherein the reference phase signal θ takes a value obtained by adding a correction value to a value in 60° increments.

5. 4. The motor driver circuit according to claim 1, wherein the loop filter includes a PI (proportional-integral) controller.

6. 4. The motor driver circuit according to claim 1, wherein the phase signal generator includes a CORDIC (Coordinate Rotation Digital Computer), and a table referenced by the CORDIC is also used as a table for a waveform generator that generates a sine wave.

7. 4. The motor driver circuit according to claim 1, which is monolithically integrated on a single semiconductor substrate.

8. A method for driving a sensor-equipped three-phase brushless motor, comprising: generating a current phase signal φ indicating a rotor position of the three-phase brushless motor based on a U-phase Hall signal, a V-phase Hall signal, and a W-phase Hall signal; The step of generating the current phase signal φ includes: generating a reference phase signal θ that changes discretely in response to edges of the U-phase Hall signal, the V-phase Hall signal, and the W-phase Hall signal; a step of calculating an error signal err=sin θ×cos φ−cos θ×sin φ; calculating the error signal err by a loop filter; an integration step of integrating the output of the loop filter to generate the current phase signal φ; A driving method including:

9. The driving method according to claim 8 , wherein the integration step performs a first-order integration of the output of the loop filter.

10. The driving method according to claim 8 , wherein the integration step performs a second-order integration of the output of the loop filter.

11. 11. The driving method according to claim 8, wherein the reference phase signal θ takes a value obtained by adding a correction value to a value in 60° increments.

12. 11. The driving method according to claim 8, wherein the loop filter includes a PI (proportional-integral) controller.

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