KR20230103620A - Motor driver, motor drive system and method for driving motor - Google Patents

Abstract

The present invention relates to a motor driver capable of quickly controlling a driving speed of a motor up to a target speed by detecting a counter electromotive force voltage without discontinuous driving of the motor. Float any one of the coils, detect the counter-electromotive force voltage of the floated specific coil, and apply a compensation value to compensate for the error between the detected counter-electromotive force voltage and the target voltage, thereby reducing the driving speed of the BLDC motor to the target speed. can increase

Description

Motor driver, motor driving system and motor driving method {MOTOR DRIVER, MOTOR DRIVE SYSTEM AND METHOD FOR DRIVING MOTOR}

The present invention relates to a motor driver, a motor driving system, and a motor driving method capable of rapidly controlling a driving speed of a motor up to a target speed by detecting a counter electromotive force voltage without discontinuous driving of the motor.

Recently, various electronic devices including home appliances such as washing machines and refrigerators use brushless direct current (BLDC) motors with high energy efficiency because they do not use brushes for commutation.

The BLDC motor performs electronic commutation that changes the current direction of the current flowing in the coils of the armature, and when the position of the rotor coincides with the commutation time, it can form a continuous rotating magnetic field that rotates the rotor. .

The BLDC motor system has a coasting section in which all three-phase motors are floated between the open loop section and the closed loop section in the initial setup section to detect the counter electromotive force of the BLDC motor and calculate the counter electromotive force voltage. By synchronizing with the driving voltage, driving efficiency can be improved.

However, the BLDC motor system has a problem in that torque ripple occurs due to discontinuous operation of the BLDC motor driving due to a coasting section.

The present invention provides a motor driver, a motor driving system, and a motor driving method capable of rapidly controlling a driving speed of a motor up to a target speed by detecting a counter electromotive force voltage without discontinuous driving of the motor.

When a closed loop period starts, the motor driver according to an embodiment of the present invention floats any one specific coil among three-phase coils to detect a counter-electromotive force voltage of the floated specific coil, and determines a relationship between the detected counter-electromotive force voltage and a target voltage. The driving speed of the BLDC motor may be increased to the target speed by applying a compensation value for compensating for the error value.

A motor driving system according to an embodiment of the present invention includes a BLDC motor including a three-phase coil; a motor driver generating a coil control signal; an inverter supplying a driving voltage using a first power supply voltage and a second power supply voltage to each of the three-phase coils in response to the coil control signal; a power supply unit supplying power voltage to the inverter; A controller controlling the motor driver, wherein the motor driver controls the inverter to float any one specific coil among the three-phase coils when a closed loop period starts, and detects a counter electromotive force voltage of the floated specific coil; , the pulse width modulation (PWM) duty of the coil control signal may be increased up to the target PWM duty by applying a compensation value for compensating for an error value between the detected back EMF voltage and the target voltage.

The motor driver may increase the PWM duty by open-loop control in an open-loop period prior to the closed-loop period.

The motor driver may increase the PWM duty to a reference value by applying PI control using a proportional-integral (PI) control coefficient to the error value.

The motor driver may increase the PWM duty to the reference PWM duty of each step by applying a different proportional-integral (PI) control coefficient for each step to the error value.

A motor driving method according to an embodiment of the present invention includes, when a closed loop period starts, floating one specific coil among three-phase coils and detecting a counter electromotive force voltage of the floated specific coil; and increasing the driving speed of the BLDC motor to the target speed by applying a compensation value for compensating for an error value between the counter electromotive force voltage and the target voltage.

A motor driver, a motor driving system, and a motor driving method according to an embodiment of the present invention float any one specific coil without discontinuity of motor driving in a setup section to detect a counter electromotive force voltage and compensate for an error between the counter electromotive force voltage and a target voltage By performing the PI control step by step, the target speed can be reached quickly.

Therefore, the motor driver, the motor driving method, and the motor driving system according to an embodiment of the present invention do not have discontinuous operation of the motor in the setup period, so the torque ripple can be reduced, and the peak of the initial drive current and the closed loop control time are reduced. can make it

1 is a diagram illustrating a sensorless BLDC motor driving system according to an embodiment of the present invention.
2 is a diagram showing a setup section of a BLDC motor according to an embodiment of the present invention.
3 is a flowchart illustrating a method for driving a BLDC motor according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

1 is a diagram showing the configuration of a BLDC motor driving system according to an embodiment of the present invention, FIG. 2 is a diagram showing the configuration of a lock determination unit of a motor driver according to an embodiment of the present invention, and FIG. It is a diagram showing a method of determining a lock state using a counter electromotive force voltage according to an embodiment of the present invention.

Referring to FIG. 1 , a sensorless brushless direct current (BLDC) motor driving system 100 according to an embodiment includes a BLDC motor 200, an inverter 300, a power supply unit 400, a motor driver 500, and a microcontroller. A unit (MicroController Unit; hereinafter referred to as MCU) 600 may be included.

The sensorless BLDC motor 200 may include a stator including three-phase coils (UC, VC, and WC) having different phases, and a rotor using permanent magnets, , the rotor is omitted in FIG.

The stator of the sensorless BLDC motor 200 includes a first coil UC having a U phase (first phase), a second coil VC having a V phase (second phase), and a W phase (third phase). It may include a third coil (WC) having.

The BLDC motor 200 may be driven according to a driving signal supplied to each of the three-phase coils UC, VC, and WC from the inverter 300, and the first to third coils UC, VC, and WC generate The magnetic force may rotate the rotor of the BLDC motor 200.

The inverter 300 operates under the control of the motor driver 500 and generates three-phase coils UC, VC, and WC of the sensorless BLDC motor 200 through the first to third nodes U, V, and W, respectively. ) may be supplied with the first power voltage VBB or the second power voltage VSS. The first power voltage VBB may be a high potential power voltage, and the second power voltage VSS may be a low potential power voltage.

In particular, the inverter 300 generates a specific coil without supplying the first and second power supply voltages VDD and VSS to any one specific coil among the three-phase coils UC, VC, and WC under the control of the motor driver 500. can be plotted.

The inverter 300 may receive the first power voltage VBB and the second power voltage VSS from the power supply unit 400 . The inverter 300 includes the 1-1st and 1-2nd coil control signals UP and UN, the 2-1st and 2-2nd coil control signals VP and VN, and the 3rd-1st and 2nd-2nd coil control signals VP and VN from the motor driver 500. 1 and 3-2 coil control signals (WP, WN) may be supplied. The coil control signals UP, UN, VP, VN, WP, and WN supplied from the motor driver 500 may be Pulse With Modulation (PWM) signals.

The inverter 300 includes a first driving unit that drives the first coil UC of the sensorless BLDC motor 200, and the first driving unit supplies a supply line of a first power voltage VBB and a second power voltage VSS. ) may include a first pull-up transistor (Tup) and a first pull-down transistor (Tun) connected in series between supply lines. A connection node between the first pull-up transistor Tup and the first pull-down transistor Tun may be connected to the first coil UC through the first node U.

The first pull-up transistor Tup is turned on while the 1-1st coil control signal UP supplied from the motor driver 500 is the gate-on voltage, and supplies the first power supply voltage VBB to the first node ( It may be applied to the first coil UC through U). The first pull-down transistor Tun is turned on while the first-second coil control signal UN supplied from the motor driver 500 is the gate-on voltage, and applies the second power supply voltage VSS to the first node ( It may be applied to the first coil UC through U).

Meanwhile, when both the 1-1 and 1-2 coil control signals UP and UN supplied from the motor driver 500 are gate-off voltages, the first pull-up transistor Tup and the first pull-down transistor Tun All are turned off so that the first node U and the first coil UC can be in a floating state.

The inverter 300 includes a second driver that drives the second coil VC of the sensorless BLDC motor 200, and the second driver connects the supply line of the first power voltage VBB to the second power voltage VSS. ) may include a second pull-up transistor Tvp and a second pull-down transistor Tvn connected in series between supply lines. A connection node between the second pull-up transistor Tvp and the second pull-down transistor Tvn may be connected to the second coil VC through the second node V.

The second pull-up transistor Tvp is turned on while the 2-1st coil control signal VP supplied from the motor driver 500 is the gate-on voltage, and supplies the first power supply voltage VBB to the second node ( It can be applied to the second coil (VC) through V). The second pull-down transistor Tvn is turned on while the 2-2nd coil control signal VN supplied from the motor driver 500 is the gate-on voltage, and applies the second power supply voltage VSS to the second node ( It can be applied to the second coil (VC) through V).

Meanwhile, when both the 2-1st and 2-2nd coil control signals VP and VN supplied from the motor driver 500 are gate-off voltages, the second pull-up transistor Tvp and the second pull-down transistor Tvn All are turned off so that the second node V and the second coil VC can be in a floating state.

The inverter 300 includes a third driving unit that drives the third coil WC of the sensorless BLDC motor 200, and the third driving unit supplies a supply line of the first power voltage VBB and the second power voltage VSS. ) may include a third pull-up transistor (Twp) and a third pull-down transistor (Twn) connected in series between supply lines. A connection node between the third pull-up transistor Twp and the third pull-down transistor Twn may be connected to the third coil WC through the third node W.

The third pull-up transistor Twp is turned on while the 3-1st coil control signal WP supplied from the motor driver 500 is the gate-on voltage, and supplies the first power supply voltage VBB to the third node ( W) may be applied to the third coil WC. The third pull-down transistor Twn is turned on while the 3-2nd coil control signal WN supplied from the motor driver 500 is the gate-on voltage, and applies the second power supply voltage VSS to the third node ( W) may be applied to the third coil WC.

Meanwhile, when both the 3-1 and 3-2 coil control signals WP and WN supplied from the motor driver 500 are gate-off voltages, the third pull-up transistor Twp and the third pull-down transistor Twn are all turned off so that the third node W and the third coil WC can be in a floating state.

The motor driver 500 controls the speed of the BLDC motor 200 by adjusting the PWM duty of the coil control signals UP, UN, VP, VN, WP, WN under the control of the MCU 600. can

As shown in FIG. 2 in the initial setup section, the motor driver 500 includes an Align & Open loop control section and a closed loop control section to control the MCU 600. Accordingly, the driving speed of the BLDC motor 200 may be increased to a target speed by stepwise increasing the PWM duty.

In the Align & Open loop control section, the motor driver 500 aligns the position of the rotor of the BLDC motor 200 and receives feedback from the BLDC motor 200 or inverter 300 It is possible to drive the BLDC motor 200 through the inverter 300 by increasing the PWM duty in an open loop control method that does not receive .

The motor driver 500 floats any one specific coil of the three-phase coils UC, VC, and WC through the inverter 300 at the end of the open loop section, and the first to third nodes from the inverter 300 The back-electromotive force (BEMF) voltage may be detected by receiving the voltage Vu of a specific coil floated through a specific node among (U, V, and W). The motor driver 500 turns off all of the control signals of a specific coil among the coil control signals UP, UN, VP, VN, WP, and WN output to the inverter 300 to the gate-off voltage, so that the three-phase coil ( UC, VC, WC) can float any one specific coil.

The motor driver 500 may be supplied with a voltage Vu of a specific coil that is floated, and may further receive a neutral point voltage in which the three-phase coils UC, VC, and WC are commonly connected in the BLDC motor 200 . The motor driver 500 may detect a difference between the voltage Vu of a specific floated coil and the neutral point voltage of the BLDC motor 200 as the counter electromotive force voltage.

As shown in Equation 1 below, the motor driver 500 may calculate an error value (speed_error) between the target voltage target_vref and the back electromotive force voltage BEMF volgate.

<Equation 1>

speed_error = target_vref - BEMF_voltage

When the error value (speed_error) is within a set range, the motor driver 500 may increase the PWM duty to the reference speed (PI_2 Start Duty) of the next step.

When the error value (speed_error) is outside the set range, the motor driver 500 calculates the PI control coefficient (Kpi) using a proportional-integral (P1) control algorithm to the error value (speed_error) as shown in Equation 2 below. A compensation value (Kpi * (speed_error)) may be calculated by applying The motor driver 500 may match the step-by-step reference speed ((PI_1 Start Duty, PI_2 Start Duty, PI_3 Start Duty)) by increasing the PWM duty by applying the compensation value (Kpi * (speed_error)).

<Equation 2>

F[N] = F[N-1] + Kpi * (speed_error), speed_error = target_vref - BEMF_voltage

The motor driver 500 applies PWM control coefficients (Kpi, i = 1, 2, 3) for each step (PI_1, PI_2, Pi_3) to the error value (speed_error) using Equation 1 in the closed loop section. Duty can be increased. In Equation 1, the PI coefficients (Kpi, i = 1, 2, and 3) are different for each stage and may be set to have a relative size of Kp1>Kp2>Kp3 and stored in an internal register.

Accordingly, the motor driver 500 can quickly increase the driving speed of the BLDC motor 200 up to the target speed in the setup section, and can drive the BLDC motor 200 at a constant speed when the target speed is reached.

3 is a flowchart illustrating a driving method of a BLDC motor driving system according to an embodiment of the present invention.

The motor driver 500 aligns the rotor position of the BLDC motor 200 and increases the PWM duty in an open loop control method that does not receive feedback from the BLDC motor 200 or the inverter 300 to 300) to drive the BLDC motor 200 (S302).

When the open loop section ends (S304, Yes), the motor driver 500 operates as a closed loop section (S306), and the motor driver 500 turns on any one specific coil of the three-phase coils (UC, VC, WC) through the inverter 300. floated, and receives the voltage Vu of the floated specific coil through a specific node among the first to third nodes U, V, and W from the inverter 300 to generate a Back-Electro Motive Force (BEMF) voltage It can be detected (S308). The motor driver 500 receives the voltage (Vu) of the specific floated coil, receives the neutral point voltage to which the three-phase coils (UC, VC, and WC) are commonly connected in the BLDC motor 200, and A difference between the voltage Vu and the neutral point voltage of the BLDC motor 200 may be detected as the counter electromotive force voltage.

The motor driver 500 may calculate an error value (speed_error) that is a difference between the target voltage (target_vref) and the back electromotive force voltage (BEMF volgate) (S312).

If the error value (speed_error) is within the set range (S312, Yes), the motor driver 500 may increase the PWM duty to the reference speed (PI_2 Start Duty) of the next step (S316).

If the error value (speed_error) is outside the set range (S312, No), the motor driver 500 performs PI control to apply the PI control coefficient (Kpi) to the error value (speed_error) to obtain a compensation value (Kpi * (speed_error) ) can be calculated (S314).

The motor driver 500 may match the step-by-step reference speed ((PI_1 Start Duty, PI_2 Start Duty, PI_3 Start Duty)) by increasing the PWM duty by applying the compensation value (Kpi * (speed_error)) (S316). The motor driver 500 may increase the PWM duty by applying the PI control coefficients (Kpi, i = 1, 2, and 3) set in each of the PI control steps (PI_1, PI_2, and Pi_3).

Accordingly, the motor driver 500 can shorten the setup period by rapidly increasing the driving speed of the BLDC motor 200 to the target speed in the setup period.

As such, the motor driver, motor driving system, and motor driving method according to an embodiment of the present invention float any one specific coil without discontinuity of motor driving in the setup section to detect the counter electromotive force voltage, and to determine the relationship between the counter electromotive force voltage and the target voltage. The target speed can be quickly reached by performing PI control step by step to compensate for the error.

Therefore, the motor driver, the motor driving method, and the motor driving system according to an embodiment of the present invention do not have discontinuous operation of the motor in the setup period, so the torque ripple can be reduced, and the peak of the initial drive current and the closed loop control time are reduced. can kill

Those skilled in the art to which the present invention pertains will be able to understand that the above-described present invention may be embodied in other specific forms without changing its technical spirit or essential features.

Therefore, it should be understood that the embodiments described above are illustrative in all respects and not limiting. The scope of the present invention is indicated by the following claims rather than the detailed description above, and all changes or modifications derived from the meaning and scope of the claims and equivalent concepts should be construed as being included in the scope of the present invention. do.

100: BLDC motor driving system 200: sensorless BLDC motor
300: inverter 400: power supply
500: motor driver

Claims (18)

At the beginning of the closed loop period, any one specific coil among the three-phase coils is floated to detect the counter-electromotive force voltage of the floated specific coil, and a compensation value is applied to compensate for an error value between the detected counter-electromotive force voltage and the target voltage. A motor driver that increases the drive speed of a BLDC motor to a target speed. The method of claim 1,
A motor driver that increases the driving speed of the BLDC motor by open-loop control in an open-loop period before the closed-loop period. The method of claim 1,
A motor driver for increasing the driving speed of the BLDC motor to a reference speed by applying PI control using a proportional-integral (PI) control coefficient to the error value. The method of claim 1,
A motor driver for increasing the driving speed of the BLDC motor to the reference speed of each step by applying a proportional-integral (PI) control coefficient different for each step to the error value. The method of claim 4,
Applying a first PI control coefficient to the error value to increase the driving speed of the BLDC motor to the reference speed of the first step,'
Applying a second PI control coefficient to the error value to increase the driving speed of the BLDC motor to the reference speed of the second step;
A motor driver for increasing the driving speed of the BLDC motor to a reference speed of a third step by applying a third PI control coefficient to the error value. The method of claim 1,
A motor driver receiving the voltage of the specific coil floating and the neutral point voltage of the three-phase coil from the BLDC motor, and detecting a difference between the voltage of the specific coil and the neutral point voltage as the counter electromotive force voltage. BLDC motors including three-phase coils;
a motor driver generating a coil control signal;
an inverter supplying a driving voltage using a first power supply voltage and a second power supply voltage to each of the three-phase coils in response to the coil control signal;
a power supply unit supplying power voltage to the inverter;
A controller for controlling the motor driver,
the motor driver
At the start of the closed loop period, controlling the inverter to float any one specific coil among the three-phase coils to detect the counter-EMF voltage of the floated specific coil and compensate for an error value between the detected counter-EMF voltage and the target voltage. A motor driver for increasing a pulse width modulation (PWM) duty of the coil control signal to a target PWM duty by applying a compensation value for The method of claim 7,
the motor driver
A motor drive system in which PWM duty is increased by open-loop control in an open-loop period prior to the closed-loop period. The method of claim 7,
the motor driver
A motor driving system for increasing the PWM duty to a reference value by applying PI control using a PI control coefficient to the error value. The method of claim 7,
the motor driver
A motor driving system for increasing the PWM duty to a reference PWM duty of each step by applying a different PI control coefficient to the error value in a plurality of steps. The method of claim 10,
the motor driver
Applying a first PI control coefficient to the error value to increase the PWM duty to a first-stage reference PWM duty;
Applying a second PI control coefficient to the error value to increase the PWM duty to a reference PWM duty of a second stage;
A motor driving system for increasing the PWM duty to a reference PWM duty of a third stage by applying a third PI control coefficient to the error value. The method of claim 7,
the motor driver
The motor driving system receiving the voltage of the specific coil floating and the neutral point voltage of the three-phase coil from the BLDC motor, and detecting a difference between the voltage of the specific coil and the neutral point voltage as the counter electromotive force voltage. At the start of the closed loop period, floating any one specific coil among the three-phase coils to detect a counter electromotive force voltage of the floated specific coil;
and increasing a driving speed of the BLDC motor to a target speed by applying a compensation value for compensating for an error value between the counter electromotive force voltage and the target voltage. The method of claim 13,
The motor driving method further comprising increasing a driving speed of the BLDC motor by open loop control in an open loop period before the closed loop period. The method of claim 13,
Increasing the driving speed of the BLDC motor to the target speed
A motor driving method of increasing the driving speed of the BLDC motor to a reference speed by applying PI control using a PI control coefficient to the error value. The method of claim 13,
Increasing the driving speed of the BLDC motor to the target speed
A motor driving method of increasing the driving speed of the BLDC motor to a reference speed of each step by applying a different PI control coefficient to the error value in a plurality of steps. The method of claim 14,
Increasing the driving speed of the BLDC motor to the target speed
increasing the driving speed of the BLDC motor to the reference speed of the first step by applying a first PI control coefficient to the error value;
increasing the driving speed of the BLDC motor to the reference speed of the second step by applying a second PI control coefficient to the error value;
and increasing a driving speed of the BLDC motor to a reference speed of a third step by applying a third PI control coefficient to the error value. The method of claim 13,
The step of detecting the counter electromotive force voltage is
The motor driving method of receiving the voltage of the floating specific coil and the neutral point voltage of the three-phase coil from the BLDC motor, and detecting a difference between the voltage of the specific coil and the neutral point voltage as the counter electromotive force voltage.

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