Driver circuit and driving method for three-phase brushless motor

Abstract

To provide a motor driver circuit capable of detecting an abnormality.SOLUTION: A motor driver circuit 200 drives a sensor-equipped three-phase brushless motor 102. A controller circuit 210 controls an inverter circuit 230 based on an U-phase hall signal HU, a V-phase hall signal HV, and a W-phase hall signal HW that are high and low according to a position of a rotor of the three-phase brushless motor. The controller circuit 210 monitors a combination of the three-phase Hall signals HU, HV, and HW, changes a count value by a first amount when transitioning to a state in which all of the signals are high or all of the signals are low, changes the count value by a second amount in a reverse direction when transitioning to other states, and determines that the count value is abnormal when the count value reaches a threshold value.SELECTED DRAWING: Figure 1

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 methods and hall sensor drive depending on the method used to detect the rotor position. Hall sensor drive uses the output (called a hall signal) of a hall sensor such as a hall element or hall IC to detect the rotor position.

[0003] When the motor is rotating normally, the three-phase Hall signals change regularly in a sequence that corresponds to the direction of rotation and at a period that corresponds to the rotation speed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6664981

[0005] [overview] The present disclosure has been made in light of such a situation, and one purpose of an embodiment thereof is to provide a motor driver circuit and a driving method capable of detecting an abnormality.

[0006] One aspect of the present disclosure relates to a motor driver circuit for driving a sensor-equipped three-phase brushless motor. The motor driver circuit includes a controller circuit that controls an inverter circuit connected to the three-phase brushless motor based on U-phase Hall signals, V-phase Hall signals, and W-phase Hall signals that go high or low depending on the rotor position of the three-phase brushless motor. The controller circuit monitors the combination of the U-phase Hall signals, V-phase Hall signals, and W-phase Hall signals, and when a transition occurs in which all are high or all are low, the controller circuit changes a count value by a first amount. When a transition occurs in any other state, the controller circuit changes the count value in the opposite direction by a second amount. When the count value reaches a threshold value, the controller circuit determines that an abnormality has occurred.

[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 U-phase Hall signal, a V-phase Hall signal, and a W-phase Hall signal indicating a rotor position of the three-phase brushless motor; monitoring a combination of the U-phase Hall signal, the V-phase Hall signal, and the W-phase Hall signal, and changing a count value by a first amount when a transition occurs in which all of the U-phase Hall signal, the V-phase Hall signal, and the W-phase Hall signal, and changing the count value by a second amount in the opposite direction when a transition occurs to any other state; and determining that an abnormality has occurred when the count value reaches a threshold value.

[0008] Any combination of the above components, or mutual substitution of the components or expressions of the present disclosure between methods, devices, systems, etc., are also valid aspects of the present disclosure. [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 diagram illustrating an example of abnormality determination by the controller circuit. [Figure 4] FIG. 4 is a diagram illustrating an example of abnormality determination by the controller circuit. [Figure 5] FIG. 5 is a block diagram showing an example of the configuration of the abnormality determination function of the controller circuit. [Figure 6] FIG. 6 is a circuit diagram of a motor circuit according to a modified example.

[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 sensor-equipped three-phase brushless motor. The motor driver circuit includes a controller circuit that controls an inverter circuit connected to the three-phase brushless motor based on U-phase Hall signals, V-phase Hall signals, and W-phase Hall signals, which go high or low depending on the rotor position of the three-phase brushless motor. The controller circuit monitors the combination of the U-phase Hall signals, V-phase Hall signals, and W-phase Hall signals, and changes a count value by a first amount when the combination transitions to a state where all are high or all are low. When the combination transitions to any other state, the controller circuit changes the count value in the opposite direction by a second amount. When the count value reaches a threshold value, the controller circuit determines that an abnormality has occurred.

[0012] When an abnormality occurs in which at least one of the U-phase Hall signal, V-phase Hall signal, and W-phase Hall signal is fixed high or low, the count value approaches the threshold value and eventually reaches the threshold value. With this configuration, when at least one of the U-phase Hall signal, V-phase Hall signal, and W-phase Hall signal is fixed, it can be determined that an abnormality has occurred and error processing such as stopping operation can be performed. On the other hand, when the three-phase Hall signals chatter due to noise or other factors, this is not determined to be an abnormality, so the motor driver circuit can be prevented from stopping operation due to noise.

[0013] In one embodiment, the controller circuit may determine the rotation direction of the three-phase brushless motor based on two consecutive transitions of the combination, thereby preventing erroneous detection of the rotation direction.

[0014] In one embodiment, if the controller circuit determines that an abnormality has occurred, it may notify an external host controller.

[0015] 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.

[0016] A driving method according to one embodiment includes the steps of generating U-phase Hall signals, V-phase Hall signals, and W-phase Hall signals that indicate the rotor position of a three-phase brushless motor; monitoring a combination of the U-phase Hall signals, V-phase Hall signals, and W-phase Hall signals; changing a count value by a first amount when a transition to all high or all low occurs; and changing the count value in the opposite direction by a second amount when a transition to any other state occurs; and determining that an abnormality has occurred when the count value reaches a threshold value.

[0017] In one embodiment, the driving method may further comprise determining a rotation direction of the three-phase brushless motor based on two consecutive transitions of the combination.

[0018] (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.

[0019] 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.

[0020] 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.

[0021] 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. The hall elements 104U, 104V, and 104W, which are hall sensors, receive a hall bias voltage V generated by the motor driver circuit 200 or another power supply circuit. HBEach Hall element 104 generates a pair of Hall voltages V that indicate the rotor position of the motor 102. H+ ,V H- Output.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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 S CNT 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.

[0027] 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.

[0028] In the 120° conduction method, the state machine 212 switches the coil (driving phase) to which the driving current is supplied in synchronization with the Hall signals HU, HV, and HW (commutation control).

[0029] In the 180-degree conduction method, the state machine 212 switches the drive phase (commutation control) in synchronization with the Hall signals HU, HV, and HW. Also, in the 180-degree conduction method, waveform data SINU to SINW for sinusoidal wave drive are generated according to the rotation angle (rotor position) of the motor 102, and the inverter circuit 230 is PWM-controlled based on the waveform data SINU to SINW.

[0030] The above is the basic configuration of the motor driver circuit 200. Next, abnormality detection by the motor driver circuit 200 will be described.

[0031] 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 degrees, and the positive and negative edges of each Hall signal appear every 60 degrees. The combinations of the three-phase Hall signals HU, HV, and HW cyclically repeat (HLH), (HLL), (HHL), (LHL), (LHH), and (LLH).

[0032] Returning to FIG. 1, the controller circuit 210 monitors the combination of the U-phase Hall signal HU, the V-phase Hall signal HV, and the W-phase Hall signal HW. When the controller circuit 210 detects a transition from a state in which the U-phase Hall signal HU, the V-phase Hall signal HV, and the W-phase Hall signal HW are all high (all-high state) to a state in which they are all low (all-low state), the controller circuit 210 changes the count value COUNT by a first amount ΔUP in a first direction. Here, the first direction is defined as a direction in which the count value COUNT is increased.

[0033] Furthermore, when the controller circuit 210 detects a transition to a state (combination) other than the all-high state or the all-low state, it changes the count value COUNT by a second amount ΔDN in a second direction opposite to the first direction. Here, the second direction is a direction in which the count value COUNT decreases.

[0034] For example, it can be determined as follows: ΔUP=4, ΔDN=1.

[0035] The controller circuit 210 determines that an abnormality has occurred when the count value COUNT reaches a predetermined threshold value TH. The threshold value TH can be determined arbitrarily, but may be set to 7, for example.

[0036] 3 is a diagram illustrating an example of abnormality determination by the controller circuit 210. Here, a case where the V-phase Hall signal HV is fixed to low will be described. When the V-phase Hall signal HV is fixed to low, (LLL) occurs once per cycle. Furthermore, during one cycle, transitions to combinations other than (LLL) and (HHH) occur three times. Note that the portions where (LLH) appear consecutively are not detected as transitions in combination, and therefore the count value COUNT does not change.

[0037] Therefore, in one period, the count value COUNT is ΔC=ΔUP×1-ΔDN×3 The value changes in the first direction (increasing direction) by only ΔC. In this example, ΔC=1. In other words, if the V-phase Hall signal HV remains fixed at low, the count value COUNT will reach the threshold value TH after TH / ΔC periods, and an abnormality can be determined. If ΔC=1 and TH=7, an abnormality will be determined after 7 periods.

[0038] 4 is a diagram illustrating an example of abnormality determination by the controller circuit 210. Here, a case will be described in which the V-phase Hall signal HV and the W-phase Hall signal HW are fixed to low. In this case, (LLL) occurs once per cycle. Also, a transition to a combination other than (LLL) and (HHH) occurs only once per cycle. Note that a point where (LLL) occurs consecutively or a point where (HLL) occurs consecutively is not detected as a transition, and therefore the count value COUNT does not change.

[0039] If the V-phase Hall signal HV and the W-phase Hall signal HW remain fixed at low, the count value COUNT will reach the threshold value TH in two cycles, and it can be determined that an abnormality has occurred.

[0040] Although the abnormality in which the Hall signal is fixed to low has been described here, an abnormality in which the Hall signal is fixed to high can also be detected in the same way.

[0041] When the controller circuit 210 detects an abnormality, it may notify the host controller 106 of the occurrence of the abnormality. Upon receiving the notification of the occurrence of the abnormality, the host controller 106 can perform processing such as stopping the driving of the motor 102 by transitioning the outputs OUT# (#=U, V, W) of each phase of the motor driver circuit 200 to a high impedance state (HiZ).

[0042] The advantages of the motor driver circuit 200 according to the embodiment will be explained in comparison with several technologies.

[0043] In comparative technique 1, if a combination of three-phase Hall signals that does not match the rotation direction command occurs a certain number of times, it is determined to be an abnormality. In this technique, if the Hall signal of any phase chatters between high and low, it is determined to be an abnormality.

[0044] Furthermore, in comparative technique 1, if one of the three-phase Hall signals momentarily drops to low due to noise or the like during a period when it should be high, it is determined to be abnormal.

[0045] In contrast to this, the motor driver circuit 200 according to the embodiment can continue to drive the motor without determining that chattering in the Hall signal or a momentary transition due to noise is an abnormality.

[0046] FIG. 5 is a block diagram showing an example of the configuration of the abnormality determination function of the controller circuit 210. The controller circuit 210 includes an abnormality logic detector 214, a counter 216, and a comparator 218. The controller circuit 210 may be implemented using hardware such as a logic circuit or a field programmable gate array (FPGA), or a combination of software and a processor. The abnormality logic detector 214 generates a determination signal S1 that takes a first level when the three-phase Hall signals HU, HV, and HW are (LLL) or (HHH) and a second level otherwise. The counter 216 counts up when the determination signal S1 is at the first level and counts down when the determination signal S1 is at the second level. The counter 216 counts up or down in response to edges of the three-phase Hall signals HU, HV, and HW, depending on the determination signal S1. The comparator 218 compares the count value COUNT with a threshold value TH and asserts an abnormality detection signal ERR when COUNT≧TH.

[0047] The technology described in Patent Document 1 will be described as Comparative Technology 2. In Comparative Technology 2, a determination unit determines whether a combination of three-phase Hall signals is normal (normal logic) or otherwise (abnormal logic). If an abnormal logic is detected, the number of transitions for each of the three-phase Hall signals is counted. If the count value for one phase reaches a threshold value and the count value for another phase is zero, an abnormality is determined. This method requires three counters. In contrast, the circuit according to the embodiment can reduce the number of counters to one.

[0048] Furthermore, the motor driver circuit 200 can adjust the sensitivity of the abnormality determination based on the threshold value TH and the first and second amounts ΔUP and ΔDN, which are count widths.

[0049] Next, the detection of the rotation direction by the controller circuit 210 will be described. The controller circuit 210 determines the rotation direction of the three-phase brushless motor based on two consecutive transitions of the combination of the three-phase Hall signals HU, HV, and HW. Referring to FIG. 2, the rotation direction is not determined based on the transition from (HLH) to (HLL) alone, and if a transition to (HHL) is detected, it is determined to be the forward rotation direction. If a transition to (LHL) is subsequently detected, it is determined to be the forward rotation direction based on the two most recent transitions.

[0050] See FIG. 2. Consider a situation in which the three-phase Hall signal goes back and forth between (LHL) and (HHL) several times due to chattering from the (LHL) state. In this case, if the rotation direction is determined based on a single transition, forward and reverse rotation directions will be determined alternately. In contrast, in the rotation direction detection according to the embodiment, even if such chattering occurs, the reverse direction is not determined, and the most recent forward rotation direction detection result is considered valid.

[0051] Finally, a modified example will be described.

[0052] In the embodiment, the inverter circuit 230 is integrated into the motor driver circuit 200, but the present disclosure is not limited to this, and the inverter circuit 230 may be integrated into an IC chip separate from the motor driver circuit 200, or may be composed of discrete components.

[0053] FIG. 6 shows a circuit diagram of a motor circuit 100A according to a first modification. In the embodiment, Hall elements 104U to 104W are used as Hall sensors, but the present disclosure is not limited thereto. In the first modification of FIG. 6, a Hall IC 105 is used as the Hall sensor. The Hall IC 105 includes a Hall element and an output V H+ ,V H- The Hall IC 105# (#=U, V, W) includes a Hall amplifier that amplifies the difference between the Hall voltages V H# Resistors R11 and R12 output the Hall bias voltage V HBThis threshold voltage Vth is the Hall amplified voltage V generated by the Hall IC 105#. H# The Hall comparator 240# of the motor driver circuit 200 outputs the Hall amplified voltage V H# is compared with the threshold voltage Vth to generate a Hall signal H#.

[0054] 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.

[0055] (Addendum) The present specification discloses the following techniques.

[0056] (Item 1) A motor driver circuit for driving a sensor-equipped three-phase brushless motor, a controller circuit that controls an inverter circuit connected to the three-phase brushless motor based on a U-phase hall signal, a V-phase hall signal, and a W-phase hall signal that are high or low depending on the position of a rotor of the three-phase brushless motor; The controller circuit a motor driver circuit that monitors a combination of the U-phase hall signal, the V-phase hall signal, and the W-phase hall signal, and when a transition occurs to a state where all are high or all are low, changes a count value by a first amount, and when a transition occurs to any other state, changes the count value in the opposite direction by a second amount, and determines that an abnormality has occurred when the count value reaches a threshold value.

[0057] (Item 2) 2. The motor driver circuit of claim 1, wherein the controller circuit determines the direction of rotation of the three-phase brushless motor based on two consecutive transitions of the combination.

[0058] (Item 3) 3. The motor driver circuit according to item 1 or 2, wherein when the controller circuit determines that an abnormality has occurred, it notifies an external host controller.

[0059] (Item 4) 4. The motor driver circuit according to any one of items 1 to 3, which is monolithically integrated on a single semiconductor substrate.

[0060] (Item 5) A method for driving a sensor-equipped three-phase brushless motor, comprising: generating a U-phase Hall signal, a V-phase Hall signal, and a W-phase Hall signal indicative of a rotor position of the three-phase brushless motor; monitoring a combination of the U-phase Hall signal, the V-phase Hall signal, and the W-phase Hall signal, and when a transition occurs in which all of the signals are high or all are low, changing a count value by a first amount, and when a transition occurs in any other state, changing the count value by a second amount in the opposite direction; determining that an abnormality has occurred when the count value reaches a threshold value; A driving method comprising:

[0061] (Item 6) 6. The driving method according to item 5, further comprising the step of determining a rotation direction of the three-phase brushless motor based on two consecutive transitions of the combination. [Explanation of symbols]

[0062] 102 Three-phase brushless motor 104 Hall element 105 Hall IC 106 Host Controller 200 Motor driver circuit 210 Controller Circuit 220 Pre-driver 230 Inverter Circuit 240 Hall Comparator

Claims

1. A motor driver circuit for driving a sensor-equipped three-phase brushless motor, a controller circuit for controlling an inverter circuit connected to the three-phase brushless motor based on a U-phase hall signal, a V-phase hall signal, and a W-phase hall signal, which are high or low depending on the position of a rotor of the three-phase brushless motor; The controller circuit A motor driver circuit that monitors a combination of the U-phase hall signal, the V-phase hall signal, and the W-phase hall signal, and when a transition occurs to a state where all are high or all are low, changes a count value by a first amount, and when a transition occurs to any other state, changes the count value in the opposite direction by a second amount, and determines that an abnormality has occurred when the count value reaches a threshold value.

2. The motor driver circuit of claim 1 , wherein the controller circuit determines a direction of rotation of the three-phase brushless motor based on two consecutive transitions of the combination.

3. 3. The motor driver circuit according to claim 1, wherein when the controller circuit determines that an abnormality has occurred, it notifies an external host controller.

4. 3. The motor driver circuit according to claim 1, wherein the motor driver circuit is monolithically integrated on a single semiconductor substrate.

5. A method for driving a sensor-equipped three-phase brushless motor, comprising: generating a U-phase Hall signal, a V-phase Hall signal, and a W-phase Hall signal indicative of a rotor position of the three-phase brushless motor; monitoring a combination of the U-phase Hall signal, the V-phase Hall signal, and the W-phase Hall signal, and when a transition occurs between all high and all low, changing a count value by a first amount, and when a transition occurs to any other state, changing the count value by a second amount in the opposite direction; determining that an abnormality has occurred when the count value reaches a threshold value; A driving method comprising:

6. 6. The driving method according to claim 5, further comprising the step of determining a rotation direction of the three-phase brushless motor based on two consecutive transitions of the combination.

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