KR102311288B1 - Method for controlling acceleration of a switched reluctance motor - Google Patents

Abstract

A driving circuit for driving a switched reluctance motor and a method of operating the same are disclosed. A driving circuit for driving a switched reluctance motor (SR motor) according to the technical concept of the present disclosure includes at least two position detection sensors disposed around a rotor of the SR motor, and the at least two position detection sensors. a position sensor unit outputting at least two position sensing signals sensed by the The SR motor driver applies the driving voltage to the plurality of winding coils and generates the plurality of switching signals, and detects the rotation speed and rotation direction of the SR motor based on the at least two position sensing signals to determine the SR and a driving controller that adjusts the plurality of switching signals so that the motor reaches a set rotation direction and target speed, wherein the driving controller generates the plurality of switching signals based on a low-frequency reference signal during initial driving, When a rotation direction coincides with a set rotation direction and the rotation speed reaches a reference speed, the plurality of switching signals may be generated based on the at least two position sensing signals.

Description

Method for controlling acceleration of a switched reluctance motor

The technical idea of the present disclosure relates to a driving circuit for driving a switched reluctance motor (hereinafter referred to as an 'SR motor') and an operating method thereof, and more particularly, the driving circuit controls the acceleration of the SR motor. it's about how to

The SR motor is a motor that generates rotational force by using the torque generated according to the change in reluctance. SR motors have recently received wide attention due to their high performance and durability, and their simple structure. The SR motor may be used as a driving device for various home appliances, such as washing machines, refrigerators, air conditioners, and cookers, various transport machines, and medical equipment. The system on which the SR motor is mounted may feed back the speed of the SR motor and control the SR motor to rotate at a desired speed based on the feedback result.

On the other hand, when a voltage is applied to the SR motor according to the initial position of the rotor, the SR motor may rotate in the reverse direction. Accordingly, there is a need for a method capable of preventing the reverse rotation of the SR motor and stably accelerating the SR motor.

SUMMARY An object of the present disclosure is to provide an SR motor driving circuit that initially drives the SR motor so that the SR motor rotates when the SR motor is initially driven, and an operating method thereof.

SUMMARY An object of the present disclosure is to provide an SR motor driving circuit for controlling acceleration of an SR motor so that reverse rotation does not occur, and an operating method thereof.

A driving circuit for driving an SR motor according to the technical spirit of the present disclosure includes at least two position detection sensors disposed around a rotor of the SR motor, and at least two position detection sensors sensed by the at least two position detection sensors. A position sensor unit that outputs position sensing signals, a voltage conversion circuit that converts a received input voltage into a driving voltage, is connected to a plurality of winding coils of the SR motor, and converts the driving voltage based on a plurality of switching signals to the plurality of The SR motor driver and the plurality of switching signals applied to the winding coils of a driving controller that adjusts the plurality of switching signals to reach a target speed, wherein the driving controller generates the plurality of switching signals based on a low-frequency reference signal during initial driving, and the rotation direction is set in a rotation direction and when the rotation speed reaches the reference speed, the plurality of switching signals may be generated based on the at least two position sensing signals.

According to the SR motor driving circuit for controlling the acceleration of the SR motor and the operating method thereof according to the technical spirit of the present disclosure, when the SR motor is initially driven, the SR motor is driven based on a low-frequency reference signal, and the SR motor is set in a direction When rotating normally, the SR motor is driven based on the position of the rotor of the SR motor and the speed of the SR motor is controlled, thereby preventing the SR motor from rotating in the reverse direction and driving the SR motor stably.

1 is a block diagram illustrating an SR motor driving system according to an exemplary embodiment of the present disclosure.
2A and 2B are diagrams illustrating a structure and a basic operating principle of an SR motor according to an exemplary embodiment of the present disclosure;
3 is a diagram illustrating the configuration of an SRM driver according to an exemplary embodiment of the present disclosure.
4 is a diagram illustrating an excitation order of coils for driving an SR motor according to an exemplary embodiment of the present disclosure.
5 is a diagram illustrating waveforms of switching signals for driving an SR motor according to an exemplary embodiment of the present disclosure.
6 is a view for explaining an initial driving method of an SR motor system according to an exemplary embodiment of the present disclosure.
7 is a view for explaining a method of detecting a speed of an SR motor according to an exemplary embodiment of the present disclosure.
8 is a view for explaining a method of driving an SR motor system according to an exemplary embodiment of the present disclosure.
9 is a view for explaining a method of operating an SR motor system according to an exemplary embodiment of the present disclosure.

Hereinafter, embodiments of the technical idea of the present disclosure will be described in detail with reference to the accompanying drawings. The same reference numerals are used for the same components in the drawings, and duplicate descriptions thereof are omitted.

1 is a block diagram illustrating an SR motor driving system according to an exemplary embodiment of the present disclosure, and FIGS. 2A and 2B are diagrams illustrating the structure and basic operating principle of an SR motor according to an exemplary embodiment of the present disclosure. The SR motor system 10 according to an exemplary embodiment of the present disclosure may be mounted on a cooking appliance such as a mixer, a cooker, or a blender. However, the present invention is not limited thereto, and the SR motor system 10 may be mounted on various home appliances such as washing machines, refrigerators, and air conditioners, various transportation machines, and medical equipment. The SR motor system 10 may operate based on the control of the main controller 20 that generally controls the operation of the mounted home appliance. For convenience of description, the main controller 20 will be illustrated together.

Referring to FIG. 1 , the SR motor system 10 includes an SR motor 110 , an SR motor driver 120 (hereinafter referred to as an SRM driver), a position sensor unit 130 , a drive controller 140 , and a voltage conversion circuit. (150). The SR motor driver 120 , the position sensor unit 130 , the driving controller 140 , and the voltage conversion circuit 150 may be referred to as driving circuits for driving the SR motor 110 .

The SR motor 110 may obtain a rotational force by using a reluctance torque generated according to a change in magnetoresistance. Referring to FIG. 2A , the SR motor 110 may include a stator 11 and a rotor 12 . The stator 11 and the rotor 12 may be made of magnetic materials having high magnetic permeability, for example, may have a structure in which silicon steel plates are stacked. The SR motor 110 may have a double salient pole structure in which both the stator 11 and the rotor 12 have a salient pole structure. The stator 11 and the rotor 12 each include a plurality of silent-poles. A coil 13 is wound around the salient poles of the stator 11 . A shaft of the SR motor 110 is connected to the center of the rotor 12 , and a sensor magnet rotating simultaneously with the rotor 12 may be mounted on the shaft or the rotor 12 .

Hereinafter, the present disclosure will be described as an example that the SR motor 110 has a four-phase motor structure. However, the technical spirit of the present disclosure is not limited thereto, and the structure of the SR motor 110 may be varied.

The stator 11 of the SR motor 110 includes eight salient poles (eg, A pole, B pole, C pole, D pole, A' pole, B' pole, C' pole, D' pole), The rotor 12 may include six salient poles. A coil is wound on the salient poles of the stator 11 facing each other. In FIG. 2a, the coil 13 is shown to be wound around A pole and A' pole, but this is for convenience of explanation, A pole and A' pole, B pole and B' pole, C pole and C' pole, An A-phase coil, a B-phase coil, a C-phase coil and a D-phase coil may be wound on the D pole and the D' pole, respectively.

2A and 2B, when a voltage is applied to both ends of the coil 13, that is, when the coil 13 is energized and a current flows in the coil 13, the salient poles on which the coil 13 is wound are excitation (excitation). ), and magnetic flux is generated in a direction orthogonal to the direction of the current. For example, depending on the winding direction of the coil 13 wound on the A pole and the A' pole, when the current I flows from the right to the left of the A pole, the A pole and the A' pole are excited and orthogonal to the current I A magnetic flux is generated in the F1 direction. As the magnetic flux passes through the rotor 12 , a current is generated in the rotor 12 , and as the magnetic flux of the stator 11 and the magnetic flux of the rotor 12 link together, a torque is generated. Hereinafter, in the present disclosure, the expression that the salient pole is excited will be used in the same way as the meaning that the coil 13 wound on the salient pole is energized and thus excited.

As the magnetic flux passes through the rotor 12 , a current is generated in the rotor 12 , and as the magnetic flux of the stator 11 and the magnetic flux of the rotor 12 link together, a torque is generated. That is, torque may be generated by the magnetic attraction force acting between the stator 11 and the rotor 12 . By sequentially applying voltage to the coils of phase A, phase B, phase C, and phase D, the rotor 12 may rotate.

Continuing to refer to FIG. 1 , the voltage conversion circuit 150 may generate a driving voltage Vdc suitable for driving the SR motor 110 based on the received input voltage Vin. For example, the input voltage Vin may be a commercial AC voltage, and the voltage conversion circuit 150 may rectify the AC voltage and convert it into a driving voltage Vdc which is a DC voltage. The voltage conversion circuit 150 may determine and vary the voltage level of the driving voltage Vdc based on the control of the driving controller 140 . However, the present invention is not limited thereto, and in an embodiment, the voltage conversion circuit 150 may determine and vary the voltage level of the driving voltage Vdc based on the control of the main controller 20 .

The SRM driver 120 (or referred to as an SRM inverter) applies the driving voltage Vdc to the coils of the SRM motor 110 (eg, A-phase, B-phase, C-phase and D-phase coils) through a switching operation. can be applied to each. The SRM driver 120 may apply the driving voltage Vdc provided from the voltage conversion circuit 150 to the coils of the SRM motor 110 .

The SRM driver 120 may include switching elements (Q1 to Q6 of FIG. 3 to be described later), and the switching elements are 'turned-on' or 'turned-off' in response to the switching signals SSWs to form a coil. voltage can be applied to them. In addition, the SRM driver 120 may output sensing signals Ssen for sensing the state of the SR motor 110 , for example, sensing signals Ssen for sensing current, temperature, voltage, and the like.

The position sensor unit 130 provides position sensing signals PSS1 and PSS2 corresponding to the angular position of the rotor 12 . In an embodiment, the position sensor unit 130 may include a plurality of Hall sensors disposed close to the sensor magnet. For example, the position sensor unit 130 may include a first Hall sensor 131 and a second Hall sensor 132 . The first Hall sensor 131 and the second Hall sensor 132 detect a magnetic signal of the sensor magnet when the rotor 12 rotates, and respectively, a first position sensing signal PSS1 and a second position sensing signal ( PSS2) can be output.

The driving controller 140 may control driving of the SR motor 110 . The drive controller 140 receives, as a drive control signal, commands for whether to operate the SR motor 110, a rotation direction, a rotation speed, a voltage setting, etc. from the main controller 20, and based on the received drive control signal, the SR motor It is possible to control the overall operation of the system 10 , that is, an operation for driving the SR motor 110 .

The drive controller 140 may control initial driving, low speed driving, medium speed driving, high speed driving, acceleration, stopping, and emergency stop of the SR motor 110 , and control modules and/or control modules for such driving or braking control. circuits may be provided. For example, the control modules may be implemented in hardware or software (or firmware), or a combination of hardware and software.

In an embodiment, the driving controller 140 may be implemented as a microcontroller (or microcomputer). However, the present invention is not limited thereto, and the driving controller 140 may include a central processing unit (CPU), a processor, a digital signal processing (DSP), an application processor (AP), a micro controller unit (MCU), or a field (FPGA). It can be implemented in various forms such as a programmable gate array).

The driving controller 140 may include a pulse width modulation (PWM) signal generator 141 , and the PWM signal generator 141 may generate PWM signals and provide the PWM signals as switching signals SSWs. . The PWMW signal generator 141 may generate PWM signals, that is, the switching signals SSWs, based on the position sensing signals PSS1 and PSS2 or a reference signal, and a predetermined control signal and sensing signals Ssen. ) based on the PWM signal duty ratio (duty ratio) can be adjusted. In this case, the reference signal is a low frequency signal of a predetermined frequency or less and may be a virtual sensing signal replacing the position sensing signals PSS1 and PSS2 during initial driving. The reference signal may be generated internally in the driving controller 140 or may be provided externally (eg, the main controller 20 or other circuit). In an embodiment, the PWM signal generator 141 may be implemented as a component separate from the driving controller 140 .

The switching signals SSWs generated by the PWM signal generator 141 may be provided to the SRM driver 120 . Although not shown, the SR motor system 10 further includes a level shifter circuit, and the switching signals SSWs have a voltage level through the level shifter circuit to control switching elements provided in the SRM driver 120. The level-converted and level-converted switching signals SSWs may be provided to the SRM driver 120 .

The driving controller 140 may control the PWM signal generator 141 to generate the switching signals SSWs based on the set rotation direction and speed. The drive controller 140 detects the rotation speed of the SR motor 110 based on the position sensing signals PSS1 and PSS2, and based on the sensing signal Ssen output from the SRM driver 120, the SRM motor ( The amount of current flowing through the coils of 110 can be detected, and the current flowing through the coils of the SRM motor 110 based on the difference between the target speed according to the speed command and the rotation speed (ie, the current speed) of the SR motor 110 . In order to increase or decrease the amount of current, the PWM signal generator 141 may control the duty ratio of the switching signals SSWs to be adjusted.

On the other hand, when the driving controller 140 is initially driven (eg, in the starting stage), the PWM signal generator 141 is not the position sensing signals PSS1 and PSS2, but the switching signals SSWs based on the low-frequency reference signal. can be controlled to create The driving controller 140 may gradually increase the frequency of the reference signal.

In an embodiment, the driving controller 140 may control the voltage conversion circuit 150 to generate a driving voltage Vdc of a voltage level lower than a target voltage level (eg, a default voltage level) during initial driving. The driving controller 140 may control the voltage conversion circuit 150 to increase the voltage level of the driving voltage Vdc according to the increase in the frequency of the reference signal.

In this case, the driving controller 140 may determine whether the SR motor 110 normally rotates in a forward direction, for example, a direction set under the control of the main controller 20 based on the position sensing signals PSS1 and PSS2 . When it is determined that the SR motor 110 rotates in the forward direction, the driving controller 140 may drive the SR motor 110 based on the position sensing signals PSS1 and PSS2. In other words, when the driving controller 140 determines that the SR motor 110 rotates at a speed greater than or equal to a predetermined reference speed in the forward direction, the PWM signal generator 141 switches the switching signals based on the position sensing signals PSS1 and PSS2. (SSWs) can be controlled to be created. Also, when it is determined that the SR motor 110 rotates in the forward direction, the driving controller 140 may control the voltage conversion circuit 150 to generate the driving voltage Vdc of the target voltage level thereafter.

In this way, the drive controller 140 drives the SR motor 110 based on the low-frequency reference signal when the SR motor 110 is initially driven (eg, low-speed driving), but by gradually increasing the frequency of the reference signal, By increasing the speed of the SR motor 110 and driving the SR motor 110 based on the position sensing signals PSS1 and PSS2 when the SR motor 110 operates at medium or high speed, the SR motor 110 It is possible to control to operate at a set speed based on the feedback of the operation state of .

For example, during initial driving, the PWM signal generator 141 generates the switching signals SSWs based on a low-frequency reference signal provided from the driving controller 140 or an external signal generator, and the frequency of the reference signal is can be increased gradually. The initial frequency of the reference signal may be 10 Hz (hertz) or less, and in an embodiment, the initial frequency of the reference signal may be 0 Hz. The voltage conversion circuit 150 may generate the driving voltage Vdc of a low voltage level, for example, the voltage level of the driving voltage Vdc is the minimum voltage at which the SRM driver 120 can operate normally during initial driving. level, for example, the minimum voltage level capable of turning on (or turning off) the switching elements included in the SRM driver 120 , or may be close to the minimum voltage level. The voltage conversion circuit 150 may increase the voltage level of the driving voltage Vdc.

From the point in time when the SR motor 110 rotates at a stable speed, for example, a reference speed or more in the forward direction, the PWM signal generator 141 generates the switching signals SSWs based on the position sensing signals PSS1 and PSS2, and the voltage The conversion circuit 150 may generate a driving voltage Vdc having a target voltage level.

When the SR motor system 10 is initially driven, when the SR motor 110 is driven according to the initial position of the rotor of the SR motor 110 based on the position sensing signals PSS1 and PSS2, for example, at the initial position Accordingly, when an excitation voltage is applied, the SR motor 110 may rotate in the reverse direction, and the frequency of the position sensing signals PSS1 and PSS2 increases so that the SR motor 110 is accelerated to a set speed, so that the reverse rotation is more Acceleration may cause the SR motor to accelerate in the reverse direction.

However, as described above, when the SR motor system 10 according to an embodiment of the present disclosure is initially driven, the SR motor 110 based on the low frequency reference signal and the low voltage driving voltage Vdc. ), and the frequency of the reference signal and the voltage level of the low electric driving voltage Vdc may be gradually increased so that the SR motor 110 becomes the reference speed in the forward direction. In the SR motor system 10, when the SR motor 110 operates stably, based on the position sensing signals PSS1 and PSS2, that is, the position information of the rotor of the SR motor 110, the SR motor 110 is a target It can be driven to rotate at high speed. Accordingly, the SR motor 110 may stably operate in a target direction and speed without the risk of reverse rotation.

3 is a diagram illustrating the configuration of an SRM driver according to an exemplary embodiment of the present disclosure. For convenience of explanation, an equivalent circuit 10 ′ representing coils wound on the SR motor ( 10 in FIG. 1 ) is also shown. The equivalent circuit 10 ′ includes four-phase coils La, Lb, Lc, and Ld wound around the stator 11 .

The SRM driver 120 may include a capacitor C1, switching elements Q1 to Q6, and a plurality of diodes D1 to D6. In an embodiment, the switching elements Q1 to Q6 may be implemented as an insulated gate bipolar transistor (IGBT), a field effect transistor (FET), a bipolar junction transistor (BJT), or the like.

The capacitor C1 is a DC link capacitor, which is connected to the first input node Ip and the second input node In (ie, the DC link), and is received through the first and second input nodes Ip and In. It is possible to stably provide the driving voltage Vdc (the driving voltage).

The first switching element Q1 and the first diode D1 have one end (terminal in the A-pole direction) of the A-phase coil La and one end of the C-phase coil Lc through the first node N1 ( terminal in the direction of the C pole). The second switching element Q2 and the second diode D2 are connected to the other end (a terminal in the A' pole direction) of the phase A coil La through the second node N2, and the third switching element Q3 ) and the third diode D3 are electrically connected to the other end (terminal in the direction of the C′ pole) of the phase C coil Lc through the third node N3 . The fourth switching element Q4 and the fourth diode D4 are connected to one end (terminal in the B-pole direction) of the B-phase coil Lb and one end of the D-phase coil Ld through the fourth node N4 ( terminal in the direction of the D pole). The fifth switching element Q5 and the fifth diode D5 are connected to the other end (a terminal in the B' pole direction) of the B-phase coil Lb through the fifth node N5, and the sixth switching element Q6 ) and the sixth diode D6 are connected to the other end (terminal in the direction of the D′ pole) of the D-phase coil Ld through the sixth node N6.

The A-phase coil La and the C-phase coil Lc may share the first switching element Q1 and the first diode D1, and the B-phase coil Lb and the D-phase coil Ld are the fourth The switching element Q4 and the fourth diode D4 may be shared. By applying such a switching element sharing method, the number of switching elements and diodes for driving the SR motor 110 may be reduced, and the circuit size of the SRM driver 120 may be reduced.

The switching elements Q1 to Q6 perform a switching operation of 'turn-on' or 'turn-off' in response to a corresponding switching signal among the switching signals S1H, S1L1, S1L2, S2H, S2L1, and S2L2. , a voltage may be applied to the coils La, Lb, Lc, and Ld. Each of the A-phase, B-phase, C-phase, and D-phase coils La, Lb, Lc, and Ld may be energized when the switching elements connected to both ends are 'turned-on'. The switching operation of the switching elements Q1 to Q6 will be described in more detail with reference to FIG. 5 .

After voltage is applied to the coils La, Lb, Lc, and Ld, the plurality of diodes D1 to D6 reflux the counter electromotive voltage generated when the switching elements Q1 to Q6 are 'turned off'. can do it

Meanwhile, the SRM driver 120 may further include a sensing unit SU for detecting the state of the SR motor 110 . For example, as illustrated, the sensing unit SU may further include a resistor Rsen for detecting a current flowing in the DC link. When the sensing voltages Vsen across the resistor Rsen are provided as a sensing signal to the driving controller 140 of FIG. 1 , the driving controller 140 receives the sensing voltages Vsen and the resistance values of the resistor Rsen. As a basis, it is possible to detect the current in the DC link.

4 is a diagram illustrating an excitation order for driving an SR motor according to an exemplary embodiment of the present disclosure. An exemplary embodiment in which the rotor 12 rotates in a clockwise direction is illustrated.

As described above with reference to FIGS. 2A and 2B , the salient poles of the stator 11 can be excited by energizing the coil wound on each of the salient poles. The rotor 12 may rotate clockwise. For example, as the first step (step1), the second step (step2), the third step (step3), and the fourth step (Step4) are sequentially progressed, the salient poles of the stator 11 are sequentially excited in a counterclockwise direction, thus Accordingly, it can be seen that the salient pole of the rotor 12 of the rotor 12, for example, the first salient pole P1 rotates clockwise.

In the first step, the A pole and the A' pole of the stator 11 are excited, and magnetic force lines are generated as shown in the direction shown. The first salient pole P1 adjacent to the A pole of the stator 11 is aligned with the A pole of the stator 11 by the magnetic attraction force. In the second stage, the B pole and B' pole are excited, and the salient pole of the rotor 12 closest to the B pole of the stator 11 in the first stage is aligned with the B pole. Accordingly, the first salient pole P1 may rotate by 15 degrees. Thereafter, when the C and C' poles are excited in the third step, and the D and D' poles are excited in the fourth step, the first salient pole P1 may rotate by 15 degrees in each step. As the first to fourth steps are sequentially performed, the rotor 12 may rotate 60 degrees clockwise, and when the first to fourth steps are performed six times, the rotor 12 rotates 360 degrees , that is, it can rotate by one. For example, if the first to fourth steps are performed 6 times for 1 second, that is, if the coils are energized at 6 Hz, the rotor 12 may rotate 60 times for 1 minute. In the SR motor 110, a frequency of 6 Hz means 6 RPM.

On the other hand, contrary to the above, when the salient poles of the stator 11 are excited in the clockwise direction, that is, when the fourth step, the third step, the second step, and the first step are sequentially performed, the rotor 12 is rotated counterclockwise. direction can be rotated.

5 is a diagram illustrating waveforms of switching signals for driving an SR motor according to an exemplary embodiment of the present disclosure. 5 shows waveforms of switching signals generated by the switching signal generator ( 141 of FIG. 1 ) based on the position sensing signals PSS1 and PSS2 when the SR motor stably operates in a target direction.

5 is, as shown in FIG. 4, the switching signals S1H, S1L1, S1L2, of the SRM driver (120 of FIG. 3) for controlling the rotor 12 of the SR motor 110 to rotate clockwise. S2H, S2L1, S2L2) waveforms are shown. As described above with reference to FIG. 1 , the switching signals S1H, S1L1, S1L2, S2H, S2L1, and S2L2 may be generated by the PWM signal generator ( 141 of FIG. 1 ). It will be described with reference to FIG. 3 together.

The PWM signal generator ( 141 of FIG. 1 ) divides the period P1 to P4 based on the combination of the position sensing signals PSS1 and PSS2 , and switches the switching signals S1H, S1L1, S1L2, S2H, S2L1 in the period P1 to P4. , S2L2) can be created. The position sensing signals PSS1 and PSS2 may have a first level, for example, a logic high level, and a second level, for example, a logic low level. In an embodiment, the section of the first level and the section of the second level of the position sensing signals PSS1 and PSS2 may be the same, and in one period (eg, section P1 to P4), the first position sensing signal The phase difference between the PSS1 and the second position sensing signal PSS2 may be 90 degrees.

First, the S1H signal and the S1L1 signal may be generated in the P1 period. In the present disclosure, generating a signal means that the signal transitions to an active level. Accordingly, the first switching element Q1 and the second switching element Q2 are 'turned-on', so that the A-phase coil La may be energized. A current may flow through the first switching element Q1 , the A-phase coil La, and the second switching element Q2 .

On the other hand, when the first switching element Q1 and the second switching element Q2 are 'pull-on' during the period P1, current is excessively introduced and it is difficult to control the amount of current. On the other hand, in the period P1, if the 'turn-on' and the 'turn-off' of the first switching element Q1 and the second switching element Q2 are repeated, that is, repeatedly switched, the amount of current may be adjusted. . However, when both the first switching element Q1 and the second switching element Q2 are repeatedly switched, a switching loss may occur. Accordingly, the second switching element Q2 is 'pull-on' and the first switching element Q1 is repeatedly switched, thereby controlling the amount of current. Accordingly, in the period P1, the S1L1 signal having an active level, for example, a logic high for controlling the second switching element Q2 to be 'pull-on', and the pulse width modulated S1H for controlling the switching of the first switching element Q1 A signal may be generated. Similarly, one of the two switching signals controlling the switching elements to be 'turned-on' in other sections, ie, sections P2, P3, and P4, may be generated as a pulse width modulated signal.

The S2H signal and the S2L1 signal may be generated in the P2 period, and in response to the S2H signal and the S2L1 signal, the fourth switching element Q4 and the fifth switching element Q5 are 'turned on' to turn on the D-phase coil Ld ) can be energized. The S1H signal and the S1L2 signal may be generated in the P3 period, and in response to the S1H signal and the S1L2 signal, the first switching element Q1 and the third switching element Q3 are 'turned on' to turn on the C-phase coil Lc ) can be energized. In addition, the S2H signal and the S2L2 signal may be generated in the P4 period, and in response to the S2H signal and the S2L2 signal, the fourth switching element Q4 and the sixth switching element Q6 are 'turned-on' to the B-phase coil (Lb) can be energized.

In this way, the switching signals S1H, S1L1, S1L2, S2H, S2L1, and S2L2 are generated in the period P1 to P4, and the switching signals S1H, S1L1, S1L2, S2H, S2L1, S2L2 are connected to the switching elements ( By being applied to Q1 to Q6), the four-phase coils La, Lb, Lc, and Ld wound on the salient poles of the stator 11 are energized counterclockwise, and the rotor 12 rotates clockwise. can A current flowing through each of the four-phase coils La, Lb, Lc, and Ld may be referred to as a phase current or an excitation current.

Meanwhile, when the SR motor is initially driven, the switching signal generator ( 141 of FIG. 1 ) may generate switching signals based on at least one reference signal, and in FIG. 5 , the position sensing signals PSS1 and PSS2 are at least It may be replaced with one reference signal.

6 is a view for explaining an initial driving method of an SR motor system according to an exemplary embodiment of the present disclosure.

Referring to FIG. 6 , the PWM signal generator 141 , the speed detector 142 , the reference signal generator 143 , and the start controller 144 provided in the drive controller 140 performs the initial driving of the SRM motor 110 . can work for

During initial driving, the PWM signal generator 141 may generate the switching signals SSWs based on at least one reference signal S_REF output from the reference signal generator 143 . Although one reference signal S_REF is illustrated in FIG. 6 , the present invention is not limited thereto. The reference signal S_REF may be a virtual sensing signal that replaces the first position sensing signal PSS1 and the second position sensing signal PSS2 during initial driving, and the reference signal generator 143 generates the first position sensing signal PSS1 ) and two reference signals S_REF having the same phase change relationship as the second position sensing signal PSS2 may be generated. For example, the two reference signals S_REF may be low-frequency signals having a phase difference of about 90 degrees.

As described with reference to FIGS. 3 to 5 , the SRM driver 120 is based on the switching signals SSWs provided from the PWM signal generator 141 and the driving voltage Vdc provided from the voltage conversion circuit 150 . to drive the SR motor 110 . When the SR motor 110 starts to be driven, that is, when it is initially driven, the voltage level of the driving voltage Vdc is lower than the target voltage level, and the reference signal S_REF may have a very low frequency close to 0 Hz.

The initial driver 144 may control the reference signal generator 143 to gradually increase the frequency of the reference signal S_REF, and also control the voltage conversion circuit 150 to gradually increase the driving voltage Vdc. have. Accordingly, the SR motor 110 may rotate in a set direction, and the rotation speed may be increased.

Meanwhile, the speed detection unit 142 may detect the rotation direction and speed of the SR motor 110 . The speed detection unit 142 receives the first position sensing signal PSS1 and the second position sensing signal PSS2 from the first Hall sensor 131 and the second Hall sensor 132 of the position sensor unit 130 , The speed of the SR motor 110 may be detected (estimated) based on the first position sensing signal PSS1 and the second position sensing signal PSS2 . _{The speed detector 142 may detect the speed ω m} (rotational speed) of the SR motor 110 through frequency analysis of the first position sensing signal PSS1 and the second position sensing signal PSS2 . The speed detecting unit 142 may detect the speed ω _m according to the speed detecting method of FIG. 7 . Also, the speed detector 142 may detect the rotation direction of the SR motor 110 based on the phase change of the first position sensing signal PSS1 and the second position sensing signal PSS2 . The speed detector 142 may provide the detected speed ω _m and the rotation direction DS to the initial driver 144 .

7 is a view for explaining a method of detecting a speed of an SR motor according to an exemplary embodiment of the present disclosure.

Referring to FIG. 7 , the position sensing signal PSS (eg, the first position sensing signal PSS1 or the second position sensing signal PSS2) may have a first level, such as a logic high and a second level, such as a logic low. can A width (eg, a section of the first level) of the position sensing signal PSS may vary depending on the arrangement of the sensor magnet and the hall sensors 131 and 132 . In the ideal position sensing signal PSS, the section of the first level and the section of the second level may be the same.

The speed detector 142 may recognize the frequency of the position sensing signal PSS by sampling (or capturing) the position sensing signal PSS. The frequency of the position sensing signal PSS may be directly proportional to the rotational speed of the SR motor 110 , that is, the speed ω _{m .} Since the rotor 12 of the SR motor 110 includes six salient poles, when the rotor 12 rotates once, six cycles occur. The speed detection unit 142 samples the position sensing signal PSS at several MHz per second, detects the rising edges RE1 and the falling edges FE of the position sensing signal PSS, and the rising edge RE By measuring the time between and the falling edge FE, one period 1P can be determined. For example, one period 1P may be the sum of the logic high time T_H and the logic low time T_L. Based on one period 1P, the frequency of the position sensing signal PSS, that is, the frequency of the SR motor 110 is detected, and as described above with reference to FIG. 4 , the frequency may be converted into a speed. For example, when the frequency of the position sensing signal PSS is 100 Hz, the speed ω _m of the SR motor 110 may be 1000 rpm. As such, the speed detector 142 may detect _{the speed ω m} of the SR motor 110 based on the position sensing signal PSS.

Continuing to refer to FIG. 6 , the drive controller 140 , for example, the initial drive tool 144 , is configured to perform an SR based on the speed ω _m and the direction DS of the SR motor 110 provided from the speed detection unit 142 . It is possible to monitor the state of the motor 110, and if it is determined that the SR motor 110 operates normally, then the PWM signal generator 141 switches the switching signals SSWs based on the position sensing signals PSS1 and PSS2. can be controlled to create For example, when it is determined that the SR motor 110 rotates at a predetermined reference speed or more in the forward direction, the initial driving unit 144 converts the input applied to the PWM signal generator 141 to the position sensing signals PSS1 and PSS2. have.

8 is a view for explaining a method of driving an SR motor system according to an exemplary embodiment of the present disclosure. 8 illustrates a medium and high speed driving method of the SR motor.

Referring to FIG. 8 , the PWM signal generator 141 , the speed detector 142 , the first subtractor 145 , the speed controller 146 , the amplifier 147 , and the second subtractor 148 provided in the driving controller 140 . ), and the current controller 149 may operate for medium and high speed driving.

The speed detection unit 142 receives the first position sensing signal PSS1 and the second position sensing signal PSS2 from the first Hall sensor 131 and the second Hall sensor 132 of the position sensor unit 130 , _{The speed speed ω m} of the SR motor 110 may be detected (estimated) based on the first position sensing signal PSS1 and the second position sensing signal PSS2 .

The first subtractor 145 may output a difference Δω _{m between the speed command ω m * and the speed ω m} detected by the speed detector 142 , that is, the speed difference. The speed controller 146 may generate a torque command τ _{m * to reduce the speed difference Δω m .} The torque command τ _m * may be amplified by the amplifier 147 by (1/τ _c ) (τ _c is the torque constant) and output as _{the current command I dc * of the DC link.} The current (I _dc ) of the DC link may be detected in the SRM driver 120 . For example, as described above with reference to FIG. 3 , the driving controller 140 may detect _{the current I dc} of the DC link based on sensing signals (eg, sensing voltages) provided from the SRM driver 120 . have. However, it not limited thereto, and detecting a current (I _dc) of the DC link in the SRM driver 120, the current of the DC link (I _dc) may be provided to the drive controller (140). The second subtractor 148 may output a difference (ΔI _dc ), ie, a current difference, between the DC link current command (I _dc *) and the detected DC link current (I _{dc ).} The current controller 149 may generate a duty ratio control signal CTRL_dt for reducing the _{current difference ΔI dc .}

The PWM signal generator 141 may generate PWM signals and provide the PWM signals to the SRM driver 120 as switching signals SSWs. As described with reference to FIG. 5 , the PWM signal generator 141 may generate PWM signals, that is, the switching signals SSWs, based on the position sensing signals PSS1 and PSS2 . Also, the PWM signal generator 141 may adjust the duty ratio of the PWM signals in response to the duty ratio control signal CTRL_dt. By adjusting the duty ratio of the PWM signal, the current difference ΔI _dc may be reduced. For example, when the speed command (ω _m *) the speed of the speed difference (Δω _m) between the (ω _m) is detected and the increase, the torque command (τ _m *) and the current command (I _dc *) of the DC link is increased, If the detected current (I _dc ) of the DC link _{is less than the current command (I dc} *) of the DC link, the duty ratio of the PWM signal may be increased such that _{the current (I dc ) of the DC link is increased.}

As such, the driving controller 140 according to an embodiment of the present disclosure detects and detects _{the speed ω m} of the SR motor 110 based on the position sensing signals PSS1 and PSS2 during medium and high-speed operation. Based on the _{detected speed (ω m} ) and the detected current (I _dc ) of the DC link, the duty of the switching signals (SSWs) to rotate the SR motor 110 according to the desired speed, ie, the speed command (ω _{m *).} You can control the rain.

9 is a view for explaining a method of operating an SR motor system according to an exemplary embodiment of the present disclosure.

6 and 9, when the SR motor 110 drive request signal is received, the PWM signal generator 141 generates the switching signals SSWs based on the low-frequency reference signal S_REF (S10) , the SRM driver 120 may apply a low voltage level driving voltage Vdc to the SR motor 110 based on the turn-on/turn-off of the switching signals SSWs ( S20 ). Accordingly, a rotational force may be generated so that the SR motor 110 rotates in a forward direction, that is, in a set direction.

The driving controller 140 may monitor the position sensing signals PSS1 and PSS2 (S40), and the driving controller 140 is the SR motor 110 based on the position sensing signals PSS1 and PSS2 in the forward direction, That is, it can be determined whether or not to rotate in a set direction (S40). When the SR motor 110 does not rotate in the forward direction, the driving controller 140 may control the SR motor 110 to rotate in the forward direction by performing steps S10 to S30 again. In an embodiment, when it is determined that the SR motor 110 rotates in the reverse direction, the drive controller 140 may control the SR motor 110 to stop or emergency stop, and then proceed to steps S10 to S40 .

When it is determined that the SR motor 110 rotates in the forward direction, the drive controller 140 may determine whether the SR motor 110 rotates at a reference speed or more ( S50 ). When the SR motor 110 does not rotate more than the reference speed, that is, when it operates at a low speed, the SRM driver 120 gradually increases the frequency of the reference signal S_REF and the voltage level of the driving voltage (S60), Steps S20 to S50 may be performed. Accordingly, the speed of the SR motor 110 may be gradually increased.

When the SR motor 110 rotates more than the reference speed, that is, when it is determined that the SR motor 110 operates normally, the driving controller 140 transmits switching signals based on the position sensing signals PSS1 and PSS2. (SSWs) may be generated (S60). For example, the PWM signal generator 141 may generate the switching signals SSWs based on the position sensing signals PSS1 and PSS2. The SRM driver 120 may apply a driving voltage to the SR motor 110 based on on/off of the switching signals SSWs ( S70 ). In this case, the level of the driving voltage may also have a set target voltage level.

As described above, in the SR motor system according to an embodiment of the present disclosure, when the SR motor 110 is initially driven, the drive controller 140 controls the SR motor 110 based on the reference signal S_REF having a preset low frequency. ), but gradually increase the frequency of the reference signal S_REF and the level of the driving voltage, and when it is determined that the SR motor 110 rotates more than the reference speed in a desired direction, for example, when driving at a medium or high speed, the position The SR motor 110 may be driven based on the sensing signals PSS1 and PSS2 .

According to the conventional driving method, in the starting step, a voltage is applied to any coil of the stator (11 in FIG. 2A ) to align the rotor 12 to the initial position, and then, based on the position sensing signals, the SR motor 110 ) is driven. However, since the initial position of the rotor 12 is not constant, when the SR motor 110 is driven based on the position sensing signals from the initial driving time, the rotor 12 moves in the opposite direction to the desired direction, that is, in the reverse direction. is likely to rotate to

However, according to the driving method according to the embodiment of the present disclosure, at the time of initial driving, the SR motor 110 is driven based on the low frequency reference signal S_REF rather than the position sensing signals, and the SR motor 110 is stable. After entering the rotating stage, the SR motor 110 may be driven at a set speed based on the position sensing signals. Accordingly, reverse rotation of the SR motor 110 is prevented and the SR motor 110 can be stably driven.

Exemplary embodiments have been disclosed in the drawings and specification as described above. Although the embodiments have been described using specific terms in the present specification, these are only used for the purpose of explaining the technical spirit of the present disclosure and are not used to limit the meaning or the scope of the present disclosure. Therefore, it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible therefrom.

10: SR motor system 110: SR motor
120: SR motor driver 130: position sensor unit
140: drive controller 150: voltage conversion circuit

Claims (8)

A driving circuit for driving a switched reluctance motor (SR motor), comprising:
a position sensor unit having at least two position sensing sensors disposed around the rotor of the SR motor and outputting at least two position sensing signals sensed by the at least two position sensing sensors;
a voltage conversion circuit for converting a received input voltage into a driving voltage;
an SR motor driver connected to a plurality of winding coils of the SR motor and applying the driving voltage to the plurality of winding coils based on a plurality of switching signals; and
The plurality of switching signals are generated so that the SR motor reaches the set rotation direction and target speed by generating the plurality of switching signals and detecting the rotation speed and rotation direction of the SR motor based on the at least two position sensing signals. a drive controller for adjusting;
The drive controller is
During initial driving, the plurality of switching signals are generated based on a low-frequency reference signal, but by increasing the frequency of the reference signal, the rotation speed of the SR motor is increased, the rotation direction coincides with the set rotation direction, and the rotation speed and generating the plurality of switching signals based on the at least two position sensing signals when a reference speed is reached. delete According to claim 1, wherein the voltage conversion circuit,
During the initial driving, the driving circuit is configured to generate the driving voltage of a voltage level lower than a target voltage level and increase the voltage level of the driving voltage. According to claim 1,
The reference speed is lower than the target speed of the SR motor. According to claim 1,
The driving circuit, characterized in that the initial frequency of the reference signal is 10 Hz (hertz) or less. According to claim 1, wherein the drive controller,
When the rotation direction does not match the set rotation direction, the SR motor is braked. The driving circuit of claim 1, and a cooking appliance comprising the SR motor. According to claim 1,
The reference signal includes at least two signals having a phase difference of 90 degrees.

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